阅读说明：本技术 掩模坯料、转印用掩模的制造方法、及半导体器件的制造方法 (Mask blank, method for manufacturing transfer mask, and method for manufacturing semiconductor device ) 是由 宍户博明 大久保亮 野泽顺 于 2020-02-20 设计创作，主要内容包括：本发明的课题在于,提供能够使掩模图案和硬掩模图案进一步微细化、以及能够提高图案品质的掩模坯料,为了解决该课题,本发明的掩模坯料(100)具备在基板(1)上依次层叠有图案形成用薄膜(3)和硬掩模膜(4)的结构,其中,硬掩模膜(4)由含有硅、氧及氮的材料形成,硬掩模膜(4)的氮的含量为2％以上且18％以下,通过X射线光电子能谱法进行分析而得到的Si2p窄谱在103eV以上的键能具有最大峰。(The mask blank (100) is provided with a structure in which a thin film (3) for pattern formation and a hard mask film (4) are sequentially laminated on a substrate (1), wherein the hard mask film (4) is formed of a material containing silicon, oxygen, and nitrogen, the content of nitrogen in the hard mask film (4) is 2% or more and 18% or less, and the narrow spectrum of Si2p obtained by analysis by X-ray photoelectron spectroscopy has a maximum peak in bond energy of 103eV or more.)

1. A mask blank having a structure in which a thin film for pattern formation and a hard mask film are laminated in this order on a substrate,

the hard mask film is formed of a material containing silicon, oxygen and nitrogen,

the hard mask film has a nitrogen content of 2 atomic% or more and 18 atomic% or less,

the hard mask film was analyzed by X-ray photoelectron spectroscopy, and the narrow spectrum of Si2p obtained by the analysis had a maximum peak of bond energy of 103eV or more.

2. The mask blank according to claim 1,

the narrow spectrum of Si2p obtained by analyzing the hard mask film by X-ray photoelectron spectroscopy has no peak in the range of the bond energy of 97eV or more and 100eV or less.

3. The mask blank according to claim 1 or 2, wherein,

the difference between the bond energy of the maximum peak in the narrow Si2p spectrum obtained by analyzing the surface of the hard mask film by X-ray photoelectron spectroscopy and the bond energy of the maximum peak in the narrow Si2p spectrum obtained by analyzing the inside of the hard mask film by X-ray photoelectron spectroscopy is 0.2eV or less.

4. The mask blank according to any one of claims 1 to 3, wherein,

the difference between the bond energy of the maximum peak in the N1s narrow spectrum obtained by analyzing the surface of the hard mask film by X-ray photoelectron spectroscopy and the bond energy of the maximum peak in the N1s narrow spectrum obtained by analyzing the inside of the hard mask film by X-ray photoelectron spectroscopy is 0.2eV or less.

5. The mask blank according to any one of claims 1 to 4, wherein,

the difference between the bond energy of the largest peak in the O1s narrow spectrum obtained by analyzing the surface of the hard mask film by X-ray photoelectron spectroscopy and the bond energy of the largest peak in the O1s narrow spectrum obtained by analyzing the inside of the hard mask film by X-ray photoelectron spectroscopy is 0.2eV or less.

6. The mask blank according to any one of claims 1 to 5, wherein,

the hard mask film has an oxygen content of 50 atomic% or more.

7. The mask blank according to any one of claims 1 to 6, wherein,

the hard mask film is formed of a material containing silicon, oxygen, and nitrogen, or a material containing silicon, oxygen, and nitrogen, and at least one element selected from the group consisting of a semimetal element and a nonmetal element.

8. The mask blank according to any one of claims 1 to 7, wherein,

the thin film for pattern formation is formed of a material containing one or more elements selected from chromium, tantalum, and nickel.

9. The mask blank according to any one of claims 1 to 8, wherein,

the pattern forming thin film is a light shielding film.

10. The mask blank according to claim 9,

a phase shift film is provided between the substrate and the light shielding film.

11. The mask blank according to any one of claims 1 to 7, wherein,

a multilayer reflective film is provided between the substrate and the pattern-forming thin film, and the pattern-forming thin film is an absorber film or a phase shift film.

12. A method for manufacturing a transfer mask using the mask blank according to any one of claims 1 to 11, comprising:

forming a transfer pattern on the hard mask film by dry etching using a fluorine-based gas, using a resist film having the transfer pattern formed on the hard mask film as a mask; and

and forming a transfer pattern on the thin film for pattern formation by dry etching using a gas containing chlorine using the hard mask film on which the transfer pattern is formed as a mask.

13. The method for manufacturing a transfer mask according to claim 12, wherein,

the dry etching using a chlorine-containing gas is performed in a state where a high bias is applied, using a chlorine-containing gas containing oxygen in which the ratio of the chlorine-containing gas is increased.

14. The method for manufacturing a transfer mask according to claim 12, wherein,

the dry etching using a chlorine-containing gas is performed under a high bias using a chlorine-based gas containing no oxygen.

15. A method of manufacturing a semiconductor device, the method comprising the steps of:

exposing and transferring the transfer pattern to a resist film on a substrate on which a semiconductor device is to be formed, using the transfer mask manufactured by the method for manufacturing a transfer mask according to any one of claims 12 to 14.

Technical Field

The present invention relates to a mask blank, a method for manufacturing a transfer mask using the mask blank, and a method for manufacturing a semiconductor device using the transfer mask manufactured from the mask blank.

Background

As a mask blank for a halftone phase shift mask, a mask blank having a structure in which a halftone phase shift film containing a metal silicide-based material, a light-shielding film containing a chromium-based material, and an etching mask film (hard mask film) containing an inorganic material are stacked on a light-transmissive substrate is known (see, for example, patent document 1). When a phase shift mask is manufactured using this mask blank, first, an etching mask film is patterned by dry etching using a fluorine-based gas, using a resist pattern formed on the surface of the mask blank as a mask. Next, the light-shielding film is patterned by dry etching using a mixed gas of chlorine and oxygen with the etching mask film as a mask. The phase shift film is further patterned by dry etching using a fluorine-based gas with the pattern of the light-shielding film as a mask.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2004/090635

Patent document 2: japanese patent No. 6158460

Disclosure of Invention

Problems to be solved by the invention

In the mask blank as described in patent document 1, the light-shielding film made of a chromium compound is required to have light-shielding performance for reducing the amount of exposure light transmitted through the phase shift film to a predetermined amount or less. When a phase shift mask is produced from the mask blank, a pattern including a light shielding tape is formed in the light shielding film. Further, it is required to satisfy a given optical density by a laminated structure of a phase shift film and a light shielding film. Meanwhile, the light-shielding film is required to function as an etching mask when the phase shift film is patterned by dry etching using a fluorine-based gas to form a phase shift pattern. In the phase shift mask completion stage, a relatively sparse pattern such as a light shielding pattern is generally formed in the light shielding film. However, in the process of manufacturing a phase shift mask from a mask blank, the light shielding film must function as an etching mask when forming a phase shift pattern, which is a fine transfer pattern, on the phase shift film. Therefore, it is desirable that a fine pattern can be formed with high dimensional accuracy also in the light-shielding film.

In dry etching of the light-shielding film containing a chromium-based material, a mixed gas of a chlorine-based gas and an oxygen gas (a chlorine-based gas containing oxygen) is used as an etching gas. In general, dry etching using such an oxygen-containing chlorine-based gas as an etching gas has a low tendency to anisotropic etching and a high tendency to isotropic etching.

In general, when a pattern is formed on a thin film for pattern formation by dry etching, etching is performed not only in the thickness direction of the film but also in the sidewall direction of the pattern formed on the thin film, that is, so-called lateral etching. In order to suppress the progress of the lateral etching, conventionally, it has been adopted to apply a bias from the opposite side of the main surface of the substrate on which the thin film is formed, and to control the etching gas to contact the film more in the thickness direction thereof, when performing the dry etching. In the case of dry etching using an ion host of an etching gas having a high tendency to become an ionic plasma such as a fluorine-based gas, the controllability of the etching direction by the application of a bias is high, and the anisotropy of etching is improved, so that the lateral etching amount of the thin film to be etched can be made small.

On the other hand, in the case of dry etching using a chlorine-based gas containing oxygen, since oxygen has a high tendency to form radical plasma, the effect of controlling the etching direction by applying a bias is small, and it is difficult to improve the anisotropy of etching. Therefore, when a pattern is formed on the light-shielding film including the chromium-based material by dry etching using a chlorine-based gas containing oxygen, the amount of lateral etching is likely to increase.

When a light-shielding film of a chromium-based material is patterned by dry etching using a chlorine-based gas containing oxygen with a resist pattern formed of an organic-based material as an etching mask, the resist pattern is etched from above and degraded. At this time, the sidewall direction of the resist pattern is also etched to be degraded. Therefore, the width of the pattern formed on the resist film is designed in advance in anticipation of the amount of the sag caused by the lateral etching. In addition, the width of the pattern formed on the resist film is designed by estimating the amount of lateral etching of the light-shielding film made of chromium-based material.

In recent years, mask blanks have been used in which an etching mask film (hard mask film) formed of a material having sufficient etching selectivity between chromium-based materials with respect to dry etching of a chlorine-based gas containing oxygen is provided on a light-shielding film of a chromium-based material. In this mask blank, a pattern is formed on the hard mask film by dry etching using the resist pattern as a mask. Then, the light-shielding film is subjected to dry etching with chlorine-based gas containing oxygen using the hard mask film having the pattern formed thereon as a mask, thereby forming a pattern on the light-shielding film. The hard mask film is generally formed of a material that can be patterned by dry etching with a fluorine-based gas. Since dry etching with a fluorine-based gas is mainly etching with ions, anisotropic etching tends to be large. Therefore, the amount of lateral etching of the pattern sidewall in the patterned hard mask film is small. In addition, in the case of dry etching with a fluorine-based gas, the amount of lateral etching tends to be small also in a resist pattern used for forming a pattern on a hard mask film. Therefore, for the light-shielding film of chromium-based material, it is also desired that the amount of lateral etching in dry etching of chlorine-based gas containing oxygen is small.

As a method for reducing the amount of lateral etching in the light-shielding film made of chromium-based material, it has been studied to greatly increase the mixing ratio of chlorine-based gas in oxygen-containing chlorine-based gas in dry etching of oxygen-containing chlorine-based gas. This is because the chlorine-based gas has a high tendency to become an ionic plasma. In dry etching using a chlorine-based gas containing oxygen in which the ratio of the chlorine-based gas is increased, it is inevitable that the etching rate of the light-shielding film made of a chromium-based material decreases. In order to compensate for the decrease in the etching rate of the light-shielding film made of chromium-based material, it has been studied to greatly increase the bias applied during dry etching (hereinafter, dry etching using a chlorine-based gas containing oxygen in which the ratio of the chlorine-based gas is increased and performed in a state where a high bias is applied is referred to as "high bias etching of a chlorine-based gas containing oxygen").

The etching rate of the light-shielding film made of chromium-based material by the high-bias etching using the oxygen-containing chlorine-based gas is at a level comparable to that in the case of dry etching under conventional etching conditions. The amount of lateral etching of the light-shielding film during etching can be made smaller than in the prior art.

Further, when the light-shielding film is patterned under high-bias etching conditions using a hard mask film having a pattern formed thereon as a mask and using a chlorine-based gas containing oxygen as an etching gas by studying and adjusting the bonding, composition, and the like of a chromium-based material in the light-shielding film, the amount of lateral etching of the pattern of the light-shielding film to be formed can be greatly reduced, and as a result, a fine pattern can be formed on the phase-shift film with good accuracy (patent document 2).

However, further miniaturization of the pattern to be formed on the phase shift film is required, and for this reason, only the above-described technique of greatly reducing the amount of lateral etching of the pattern of the light-shielding film is insufficient. Further, there is a demand for further miniaturization of a pattern to be formed on a thin film for pattern formation such as a light-shielding film, a pattern to be formed on a hard mask film, and improvement of pattern quality. This is also true for a binary mask having a light-shielding film or the like as a thin film for pattern formation, and a reflective mask having an absorber film or the like as a thin film for pattern formation.

In order to solve the above-described problems, the present invention provides a mask blank having a structure in which a thin film for pattern formation such as a light-shielding film and a hard mask film are sequentially stacked on a substrate, and the mask blank can realize further miniaturization of a pattern to be formed on the thin film for pattern formation such as a light-shielding film, a pattern to be formed on the hard mask film, and improvement of pattern quality.

In particular, the present invention provides a mask blank which has a hard mask film having excellent performance suitable for high bias etching conditions and which can achieve further miniaturization of a pattern to be formed on a thin film for pattern formation and improvement of pattern quality.

The present invention also provides a method for manufacturing a transfer mask capable of forming a fine pattern on a pattern-forming film with good accuracy by using the mask blank.

The invention also provides a method for manufacturing a semiconductor device using the transfer mask.

Means for solving the problems

The present invention has the following means as means for solving the above problems.

(scheme 1)

A mask blank having a structure in which a thin film for pattern formation and a hard mask film are laminated in this order on a substrate,

the hard mask film is formed of a material containing silicon, oxygen and nitrogen,

the hard mask film has a nitrogen content of 2 atomic% or more and 18 atomic% or less,

the narrow spectrum of Si2p obtained by analyzing the hard mask film by X-ray photoelectron spectroscopy has a maximum peak of bond energy of 103eV or more.

(scheme 2)

The mask blank according to claim 1, wherein,

the narrow spectrum of Si2p obtained by analyzing the hard mask film by X-ray photoelectron spectroscopy has no peak in the range of the bond energy of 97eV or more and 100eV or less.

(scheme 3)

The mask blank according to claim 1 or 2, wherein,

the difference between the bond energy of the maximum peak in the narrow spectrum of Si2p obtained by analyzing the surface of the hard mask film by X-ray photoelectron spectroscopy and the bond energy of the maximum peak in the narrow spectrum of Si2p obtained by analyzing the inside of the hard mask film by X-ray photoelectron spectroscopy is 0.2eV or less.

(scheme 4)

The mask blank according to any one of claims 1 to 3, wherein,

the difference between the bond energy of the maximum peak in the N1s narrow spectrum obtained by analyzing the surface of the hard mask film by X-ray photoelectron spectroscopy and the bond energy of the maximum peak in the N1s narrow spectrum obtained by analyzing the inside of the hard mask film by X-ray photoelectron spectroscopy is 0.2eV or less.

(scheme 5)

The mask blank according to any one of claims 1 to 4, wherein,

the difference between the bond energy of the largest peak in the O1s narrow spectrum obtained by analyzing the surface of the hard mask film by X-ray photoelectron spectroscopy and the bond energy of the largest peak in the O1s narrow spectrum obtained by analyzing the inside of the hard mask film by X-ray photoelectron spectroscopy is 0.2eV or less.

(scheme 6)

The mask blank according to any one of claims 1 to 5, wherein,

the hard mask film has an oxygen content of 50 atomic% or more.

(scheme 7)

The mask blank according to any one of claims 1 to 6, wherein,

the hard mask film is formed of a material containing silicon, oxygen, and nitrogen, or a material containing silicon, oxygen, and nitrogen, and at least one element selected from the group consisting of a semimetal element and a nonmetal element.

(scheme 8)

The mask blank according to any one of claims 1 to 7, wherein,

the thin film for pattern formation is formed of a material containing one or more elements selected from chromium, tantalum, and nickel.

(scheme 9)

The mask blank according to any one of claims 1 to 8, wherein,

the pattern forming thin film is a light shielding film.

(scheme 10)

The mask blank according to claim 9, wherein,

a phase shift film is provided between the substrate and the light shielding film.

(scheme 11)

The mask blank according to any one of claims 1 to 7, wherein,

a multilayer reflection film is provided between the substrate and the pattern forming thin film, and the pattern forming thin film is an absorber film or a phase shift film.

(scheme 12)

A method for manufacturing a transfer mask using the mask blank according to any one of claims 1 to 11, comprising:

forming a transfer pattern on the hard mask film by dry etching using a fluorine-based gas, using a resist film having the transfer pattern formed on the hard mask film as a mask; and

and forming a transfer pattern on the thin film for pattern formation by dry etching using a gas containing chlorine using the hard mask film on which the transfer pattern is formed as a mask.

(scheme 13)

The method for manufacturing a transfer mask according to claim 12, wherein,

the dry etching using a chlorine-containing gas is performed in a state where a high bias is applied, using a chlorine-containing gas containing oxygen in which the ratio of the chlorine-containing gas is increased.

(scheme 14)

The method for manufacturing a transfer mask according to claim 12, wherein,

the dry etching using a gas containing chlorine is performed under a high bias using a chlorine-based gas containing no oxygen.

(scheme 15)

A method of manufacturing a semiconductor device, the method comprising the steps of:

using the transfer mask manufactured by the method for manufacturing a transfer mask according to any one of claims 12 to 14, the transfer pattern is exposed and transferred to the resist film on the substrate on which the semiconductor device is to be formed.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention having the above configuration, it is possible to provide a mask blank having a structure in which a thin film for pattern formation such as a light-shielding film and a hard mask film are sequentially stacked on a substrate, and the mask blank can realize further miniaturization and improvement in pattern quality of a pattern to be formed on the thin film for pattern formation such as a light-shielding film and a pattern to be formed on the hard mask film.

In particular, according to the present invention, it is possible to provide a mask blank which has a hard mask film having excellent performance suitable for high-bias etching conditions, and which can achieve further miniaturization of a pattern to be formed on a thin film for pattern formation and improvement of pattern quality.

Further, according to the present invention, it is possible to provide a method for manufacturing a transfer mask, in which a fine pattern is formed on a pattern forming film with good accuracy by using the mask blank.

Further, according to the present invention, a method for manufacturing a semiconductor device using the transfer mask can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view of an embodiment of a mask blank of the present invention.

Fig. 2 is a schematic cross-sectional view showing a manufacturing process of the phase shift mask of the present invention.

Fig. 3 is a graph showing the results (Si2p narrow spectrum) of XPS analysis (depth direction chemical bond state analysis) performed on the mask blank of example 1.

Fig. 4 is a graph showing the results (N1s narrow spectrum) of XPS analysis (analysis of chemical bond state in the depth direction) of the mask blank of example 1.

Fig. 5 is a graph showing the results (O1s narrow spectrum) of XPS analysis (analysis of chemical bond state in the depth direction) of the mask blank of example 1.

Fig. 6 is a schematic cross-sectional view of an embodiment of a reflective mask blank of the present invention.

Fig. 7 is a schematic cross-sectional view showing a process of manufacturing a reflective mask according to the present invention.

Description of the symbols

1 light-transmitting substrate

2 phase shift film

2a phase shift pattern

3 light-shielding film (film for pattern formation)

3a, 3b light-shielding pattern

4 hard mask film

4a hard mask pattern

5a resist pattern

6b resist pattern

11 substrate

12 multilayer reflective film

13 protective film

14 absorber film (phase shift film)

15 hard mask film

16 back conductive film

100 mask blank

200 phase shift mask (mask for transfer)

300 reflection type mask blank

400 reflection type mask

Detailed Description

Hereinafter, embodiments of the present invention will be described, and the process of completing the present invention will be described first.

The present inventors have studied further miniaturization of the pattern formed on the hard mask film and improvement of the pattern quality, and as a result, have found the following.

First, it is known that a hard mask film formed of a material containing silicon and oxygen has an Si-N bond (containing nitrogen) in the film and does not have an Si-N bond (containing no nitrogen) in the film (SiO)₂) Compared with the prior art, the etching rate of the fluorine gas is high, and the hard mask film can be quickly and completely etched. The etching of the hard mask film can be completed in a short time, and the resist can be thinned accordingly. The resist can be prevented from being finer by thinning the resistThe skew of the pattern is etched, thereby realizing the formation of a finer resist pattern.

When the etching rate of a certain film is increased, the etching time for patterning the film is shortened. If the etching time when patterning the film is short, the time during which the side wall of the film is exposed to the etching gas is short, resulting in a decrease in the amount of lateral etching. In addition, according to the present invention, the hard mask film can be quickly etched. This makes it possible to form a pattern having smooth (smooth) sidewalls with a small sidewall roughness, and to improve the verticality of the sidewalls of the pattern.

In particular, when the etching rate of a certain film is significantly increased, the etching time in the film thickness direction is significantly shortened, and the time during which the sidewall of the certain film is exposed to the etching gas is significantly shortened. Thus, the side wall roughness of the pattern of the hard mask film is smaller, and a pattern having smoother (smooth) side walls can be formed.

Second, it is known that when a hard mask film is formed of a material containing silicon and oxygen, if the film has an Si — N bond (containing nitrogen), the film does not have an Si — N bond (containing no nitrogen) (SiO)₂) In contrast, the contact angle after HMDS (Hexamethyldisilazane) treatment was large, and the resist adhesion was good. Therefore, distortion of the finer resist pattern can be prevented, and formation of the finer resist pattern can be achieved. When the resist pattern is made finer, the adhesion is reduced by that amount, but in the present invention, the influence thereof can be suppressed.

In the present invention, the distortion of the finer resist pattern can be prevented, and the formation of the finer resist pattern can be realized. As a result, the pattern formed on the hard mask film can be further miniaturized.

In order to obtain both the first and second effects, it is necessary to detect at least the maximum peak (maximum peak is not less than the detection limit) of the narrow spectrum of N1s obtained by X-ray Photoelectron Spectroscopy (XPS), that is, to substantially contain nitrogen.

In order to obtain both the first and second effects, the content of nitrogen in the hard mask film made of a material containing silicon, oxygen, and nitrogen is preferably 2 atomic% or more, more preferably 3 atomic% or more, further preferably 4 atomic% or more, and further preferably 5 atomic% or more. When the content of nitrogen is too small, the above-described two effects are not easily obtained.

The narrow spectrum of N1s obtained by analyzing the hard mask film of the present invention made of a material containing silicon, oxygen, and nitrogen by X-ray photoelectron spectroscopy has a maximum peak of bond energy of 398eV or more.

Next, the present inventors have studied the reduction of the function as a hard mask and the resulting reduction of the pattern transfer performance.

As a result, third, it is found that the function as a hard mask tends to be lowered (the etching resistance to chlorine-based gas is somewhat lowered) as the amount of nitrogen increases in the hard mask film formed of a material containing silicon, oxygen, and nitrogen. Further, it is found that when the nitrogen content is 18 atomic% or less, the function as a hard mask is suppressed from being lowered, and the pattern transfer performance is prevented from being lowered. In addition, it is also known that a narrow spectrum of Si2p obtained by analyzing a hard mask film made of a material containing silicon, oxygen, and nitrogen by X-ray photoelectron spectroscopy must have a maximum peak in bond energy of 103eV or more. By making SiO in the hard mask film₂The function as a hard mask can be ensured by the high ratio of the existence of the bond and the Si-O bond. By providing the hard mask film with these features, the third tendency can be suppressed while maintaining both the first and second effects.

It is found that the third tendency is large under the high bias etching condition of the chlorine-based gas containing oxygen, and the function as the hard mask tends to be reduced (the etching resistance to the chlorine-based gas is reduced). That is, it is found that the Edge portion of the pattern of the hard mask film is easily etched, and thus Line Edge Roughness (LER) is deteriorated, and the accuracy of the formed light shielding pattern tends to be deteriorated.

In the case of a hard mask film formed of a material containing silicon, oxygen, and nitrogen, the nitrogen content is preferably 15 atomic% or less, more preferably 12 atomic% or less, still more preferably 10 atomic% or less, and still more preferably 8 atomic% or less.

In general, when a thin film for pattern formation is dry-etched, both etching by chemical reaction and etching by physical action are performed. Etching by chemical reaction was performed by the following process: the etching gas in the plasma state contacts the surface of the thin film and bonds with silicon or metal elements in the thin film to generate a low-boiling-point compound (e.g., SiF)₄、CrO₂Cl₂Etc.) to sublimate. In etching by chemical reaction, silicon or a metal element in a state of being bonded to another element (for example, O, N or the like) is cleaved in the bonding, and a compound having a low boiling point is generated. In contrast, physical etching proceeds as follows: when the plasma of ions in the etching gas accelerated by the bias collides with the surface of the thin film (this phenomenon is also referred to as "ion impact"), each element including silicon or a metal element on the surface of the thin film physically bounces off (at this time, the bond between the elements is broken), and the silicon or the metal element and a compound having a low boiling point are generated and sublimated.

The high bias etching is dry etching which improves utilization of physical action as compared with dry etching under ordinary conditions. Etching using physical action significantly contributes to etching in the film thickness direction, but less contributes to etching in the sidewall direction of the pattern.

On the other hand, etching by chemical reaction contributes to any of etching in the film thickness direction and etching in the sidewall direction of the pattern (lateral etching).

Next, the present inventors have studied a hard mask film suitable for high bias etching conditions of a chlorine-based gas containing oxygen.

As a result, it was found that, in the case where a hard mask film formed of a material containing silicon, oxygen, and nitrogen has an Si — Si bond in the film and a peak corresponding to the Si — Si bond is observed in a narrow Si2p spectrum obtained by analysis by X-ray photoelectron spectroscopy, the function as a hard mask tends to be significantly reduced (the etching resistance to chlorine-based gas is significantly reduced) as the number of Si — Si bonds increases. Therefore, it is found that the degradation of the pattern transfer performance cannot be avoided. This tendency was found to be further increased under the high bias etching conditions of the chlorine-based gas containing oxygen.

In the present invention, it is preferable that a peak corresponding to an Si — Si bond (a peak in a range of a bond energy of 97eV or more and 100eV or less) is not observed in a narrow Si2p spectrum obtained by analyzing a hard mask film formed of a material containing silicon, oxygen, and nitrogen by an X-ray photoelectron spectroscopy (detection limit value or less). Such a hard mask film is considered to have no Si — Si bond or to have a very low presence ratio of Si — Si bond. This makes it possible to avoid the influence of the fourth unfavorable tendency described above with respect to the hard mask. As a result, the deterioration of the pattern transfer performance due to the hard mask can be avoided.

Next, the present inventors studied the kind of bond and bond energy (narrow spectrum) contained in the hard mask film. Specifically, attention is paid to the difference between the bond energy of the maximum peak in the Si2p narrow spectrum obtained by analyzing the surface of the hard mask film by the X-ray photoelectron spectroscopy and the bond energy of the maximum peak in the Si2p narrow spectrum obtained by analyzing the inside of the hard mask film by the X-ray photoelectron spectroscopy (hereinafter, this is referred to as the bond energy difference of the Si2p narrow spectrum).

As a result, in order to obtain high controllability in etching processing of the hard mask film, it is preferable that the hard mask film formed of a material containing silicon, oxygen, and nitrogen has a relatively small bond energy difference in the narrow spectrum of Si2p and has more uniform (preferably substantially the same) bond energy in the thickness direction (depth direction) of the film. Specifically, it is found that the bond energy difference of the narrow spectrum of Si2p is preferably 0.2eV or less, more preferably 0.1eV or less.

Next, attention is focused on the difference between the bond energy of the maximum peak in the N1s narrow spectrum obtained by analyzing the surface of the hard mask film by the X-ray photoelectron spectroscopy and the bond energy of the maximum peak in the N1s narrow spectrum obtained by analyzing the inside of the hard mask film by the X-ray photoelectron spectroscopy (hereinafter, this is referred to as the bond energy difference of the N1s narrow spectrum).

As a result, in order to obtain high controllability in the etching process of the hard mask film, it is preferable that the hard mask film formed of a material containing silicon, oxygen, and nitrogen has a relatively small bond energy difference in the narrow spectrum of N1s and has more uniform (preferably substantially the same) bond energy in the thickness direction (depth direction) of the film. Specifically, it is found that the bond energy difference of the narrow spectrum of N1s is preferably 0.2eV or less, more preferably 0.1eV or less.

Note that the difference between the bond energy of the largest peak in the O1s narrow spectrum obtained by analyzing the surface of the hard mask film by X-ray photoelectron spectroscopy and the bond energy of the largest peak in the O1s narrow spectrum obtained by analyzing the inside of the hard mask film by X-ray photoelectron spectroscopy (hereinafter, this is referred to as the bond energy difference of the O1s narrow spectrum) is also focused.

As a result, in order to obtain high controllability in etching of the hard mask film, it is preferable that the hard mask film formed of a material containing silicon, oxygen, and nitrogen has a relatively small difference in bonding energy of the O1s narrow spectrum, and the bonding energy is more uniform (preferably substantially the same) in the thickness direction (depth direction) of the film. Specifically, it is found that the bond energy difference of O1s in a narrow spectrum is preferably 0.2eV or less, more preferably 0.1eV or less.

On the other hand, it was found that, even when the light-shielding film is patterned by dry etching under high bias etching conditions using the hard mask film having the above-described configuration as a mask and using a chlorine-based gas containing no oxygen as an etching gas, the same action and effect as those of the case of high bias etching conditions using a chlorine-based gas containing oxygen are exhibited.

Hereinafter, the detailed configuration of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals.

< first embodiment >

[ mask blank and production thereof ]

Mask blank

Fig. 1 shows a schematic configuration of a mask blank according to a first embodiment of the present invention. The mask blank 100 shown in fig. 1 has a structure in which a phase shift film 2, a light-shielding film 3 (a pattern-forming thin film), and a hard mask film 4 are sequentially stacked on one main surface of a light-transmissive substrate 1. The mask blank 100 may have a structure in which a resist film is laminated on the hard mask film 4 as necessary. Hereinafter, the main components of the mask blank 100 will be described in detail.

[ translucent substrate ]

The light-transmissive substrate 1 is formed of a material having good transmittance to exposure light used in an exposure step of lithography. As such a material, synthetic quartz glass, aluminosilicate glass, soda-lime glass, and low thermal expansion glass (SiO)₂-TiO₂Glass, etc.), other various glass substrates. In particular, a substrate using synthetic quartz glass has high transmittance to an ArF excimer laser beam (wavelength: about 193nm), and thus can be suitably used as the transparent substrate 1 of the mask blank 100.

The exposure step in lithography referred to herein is an exposure step in lithography using a phase shift mask produced using the mask blank 100, and hereinafter, the exposure light is exposure light used in the exposure step. As the exposure light, any of ArF excimer laser (wavelength: 193nm), KrF excimer laser (wavelength: 248nm), and i-ray light (wavelength: 365nm) can be used, and the ArF excimer laser is preferably used for the exposure light from the viewpoint of miniaturization of the phase shift pattern in the exposure step. Therefore, an embodiment of the case where an ArF excimer laser beam is used as the exposure light will be described below.

[ phase-shift film ]

The phase shift film 2 has optical characteristics as follows: the exposure light used in the exposure transfer step has a predetermined transmittance, and the exposure light transmitted through the phase shift film 2 has a predetermined phase difference from the exposure light passing through the atmosphere only at the same distance as the thickness of the phase shift film 2.

Such a phase shift film 2 is formed here of a material containing silicon (Si). The phase shift film 2 is preferably formed of a material containing nitrogen (N) in addition to silicon. As the phase shift film 2, a material which can be patterned by dry etching using a fluorine-based gas and has sufficient etching selectivity for a CrOCN film or the like constituting the light-shielding film 3 described later is used.

The phase shift film 2 may further contain one or more elements selected from semimetal elements, nonmetal elements, and metal elements if it can be patterned by dry etching using a fluorine-based gas.

The semimetal element may be any semimetal element other than silicon. The nonmetal element may be any nonmetal element other than nitrogen, and preferably contains at least one element selected from oxygen (O), carbon (C), fluorine (F), and hydrogen (H), for example. The metal elements may be exemplified by molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), zirconium (Zr), hafnium (Hf), niobium (Nb), vanadium (V), cobalt (Co), chromium (Cr), nickel (Ni), ruthenium (Ru), tin (Sn), boron (B), germanium (Ge).

The phase shift film 2 is made of, for example, MoSiN, and the refractive index n, the extinction coefficient k, and the film thickness of the phase shift film 2 are selected so as to satisfy a predetermined phase difference (phase shift amount) (for example, 150 deg to 210 deg, preferably 160 deg to 200 deg) and a predetermined transmittance (for example, 1% to 30%) with respect to exposure light (for example, ArF excimer laser light), and the composition of the film material and the film formation conditions of the film are adjusted so as to achieve the refractive index n and the extinction coefficient k.

[ light-shielding film ]

The light-shielding film 3 is preferably formed of a material containing at least one or more elements selected from chromium and tantalum. The film structure of the light-shielding film 3 may be any of a single-layer structure and a laminated structure of two or more layers. In the case of the laminated structure, the reflection reducing effect of reducing the reflectance can be exerted on the exposure light or the inspection light at the time of defect inspection. Each of the light-shielding films having a single-layer structure and the light-shielding films having a laminated structure of two or more layers may have substantially the same composition in the thickness direction of the film or layer, or may have a composition gradient in the thickness direction of the film or layer. The film containing at least one element selected from chromium and tantalum is a film that can be patterned by dry etching using a chlorine-based gas containing oxygen or a chlorine-based gas containing substantially no oxygen.

The light-shielding film 3 is preferably formed of a material containing chromium. As a material containing chromium for forming the light-shielding film 4, in addition to chromium metal, a material containing one or more elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B), and fluorine (F) in chromium (Cr) is also cited. Generally, a chromium-based material is etched using a chlorine-based gas containing oxygen, but the etching rate of chromium metal with respect to the etching gas is not so high. From the viewpoint of increasing the etching rate with respect to the chlorine-based gas containing oxygen, a material containing chromium and one or more elements selected from oxygen, nitrogen, carbon, boron, and fluorine is preferable as a material for forming the light-shielding film 3. The material containing chromium for forming the light-shielding film 3 may contain one or more elements selected from molybdenum (Mo), indium (In), and tin (Sn). The etching rate of the chlorine-based gas containing oxygen can be further increased by containing one or more elements selected from molybdenum, indium, and tin. When the light-shielding film 3 is formed of a material containing chromium, the content of silicon is preferably 5 atomic% or less, more preferably 3 atomic% or less, and even more preferably substantially not contained. This is because when the light-shielding film 3 contains silicon, the etching rate with respect to a chlorine-based gas containing oxygen decreases, and is not preferable in dry etching of the light-shielding film 3.

In addition, when the light-shielding film 3 contains tantalum, the tantalum may contain one or more elements selected from nitrogen, oxygen, boron, and carbon in addition to tantalum metal. Examples thereof include: ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, TaBOCN, and the like. In addition, in the case where Ta or TaN is used as the light-shielding layer of the light-shielding film 3, Ta or TaN has a high reflectance with respect to exposure light, and therefore, a laminated structure in which an antireflection layer formed of TaO or the like is provided on the light-shielding layer is desired. When the light-shielding film 3 is formed of a tantalum-containing material, the content of silicon in the tantalum-containing material is preferably 5 atomic% or less, more preferably 3 atomic% or less, and even more preferably substantially not contained. In the case where the light-shielding film 3 is formed of the above-described tantalum-containing material and the light-shielding film 3 is patterned by dry etching using the hard mask film 4 as a mask, a chlorine-based gas substantially not containing oxygen may be used as an etching gas.

The light-shielding film 3 is preferably an amorphous structure or a microcrystalline structure in terms of reducing the surface Roughness and the Line Edge Roughness (LER) of the light-shielding pattern to be formed.

The light shielding film 3 is preferably formed by sputtering, and any sputtering method such as DC sputtering, RF sputtering, and ion beam sputtering may be applied. The sputtering may be a magnetron sputtering method, a Dual (Dual) magnetron method, or a normal method. By forming the light-shielding film 3 by sputtering, the light-shielding film 3 can be formed into a film having an amorphous or microcrystalline structure. The film forming apparatus may be an inline (inline) type or a single-wafer type.

The light-shielding film 3 is required to secure an Optical Density (OD) of more than 2.0 with respect to exposure light by a laminated structure with the phase-shift film 2. The optical density is preferably 2.8 or more, more preferably 3.0 or more.

[ hard mask film ]

The hard mask film 4 is formed of a material containing silicon, oxygen, and nitrogen, or a material containing silicon, oxygen, and nitrogen, and at least one element selected from a semimetal element and a nonmetal element. In this case, the hard mask film 4 may contain any semimetal element. When the semimetal element contains one or more elements selected from boron, germanium, antimony, and tellurium, it is preferable because it is expected to improve the conductivity of silicon used as a target when the hard mask film 4 is formed by a sputtering method. Examples of the nonmetal elements include carbon (C), fluorine (F), and hydrogen (H).

The oxygen content of the hard mask film 4 is preferably 50 atomic% or more, and more preferably 55 atomic% or more. In order to make the hard mask film 4 have the above-described characteristics of the narrow spectrum of Si2p, it is necessary to contain a large amount of oxygen. The oxygen content of the hard mask film 4 is preferably 65 atomic% or less, and more preferably 63 atomic% or less. This is because the hard mask film 4 has the above-described characteristics of the N1s narrow spectrum.

The hard mask film 4 is provided in contact with the surface of the light shielding film 3. The hard mask film 4 is a film formed of a material having etching selectivity to an etching gas used when etching the light-shielding film 3. The hard mask film 4 is sufficient to have a film thickness that functions only as an etching mask until the end of dry etching for forming a pattern on the light-shielding film 3, and is not limited to optical characteristics basically. Therefore, the thickness of the hard mask film 4 can be made much smaller than the thickness of the light-shielding film 3.

The thickness of the hard mask film 4 is required to be 20nm or less, preferably 15nm or less, and more preferably 10nm or less. This is because, if the thickness of the hard mask film 4 is too large, a resist film serving as an etching mask needs to be thick in dry etching for patterning the hard mask film 4. The thickness of the hard mask film 4 is required to be 2nm or more, preferably 3nm or more. This is because, if the thickness of the hard mask film 4 is too thin, the pattern of the hard mask film 4 may disappear before the dry etching for forming the light-shielding pattern on the light-shielding film 3 is completed, depending on the conditions of the high-bias etching using the chlorine-based gas containing oxygen.

In the dry etching using a fluorine-based gas for forming a pattern on the hard mask film 4, it is sufficient that the resist film of an organic material used as an etching mask has a film thickness that functions only as an etching mask until the dry etching of the hard mask film 4 is completed. Therefore, the thickness of the resist film can be reduced significantly by providing the hard mask film 4, as compared with a configuration in which the hard mask film 4 is not provided.

When the hard mask film 4 is formed of a material containing silicon, oxygen, and nitrogen, adhesion to a resist film made of an organic material tends to be low, and therefore, it is preferable to improve the adhesion of the surface by applying HMDS treatment to the surface of the hard mask film 4 (or by applying the same treatment alone or in combination with HMDS treatment).

The hard mask film 4 is preferably an amorphous structure or a microcrystalline structure in terms of reducing the surface Roughness and the Line Edge Roughness (LER) of the formed light shielding pattern.

The hard mask film 4 is preferably formed by sputtering, and any sputtering method such as DC sputtering, RF sputtering, and ion beam sputtering may be applied. The sputtering may be a magnetron sputtering method, a Dual (Dual) magnetron method, or a normal method. By forming the hard mask film 4 by sputtering, the hard mask film 4 can be made into a film of an amorphous or microcrystalline structure. The film forming apparatus may be an inline (inline) type or a single-wafer type.

As a material of the target in sputtering, a target composed of a simple substance of silicon or a target containing silicon and oxygen may be used as long as silicon is a main component.

[ resist film ]

In the mask blank 100, a resist film of an organic material is preferably formed in a thickness of 100nm or less in contact with the surface of the hard mask film 4. In the case of a fine pattern corresponding to the DRAM hp32nm generation, an SRAF (Sub-Resolution Assist Feature) having a line width of 40nm may be provided in a light-shielding pattern to be formed on the light-shielding film 3. In this case, however, the hard mask film 4 is provided as described above to suppress the film thickness of the resist film, thereby making it possible to reduce the aspect ratio of the cross section of the resist pattern formed of the resist film to 1: 2.5. Therefore, damage and detachment of the resist pattern can be suppressed during development of the resist film, during rinsing, and the like. The thickness of the resist film is more preferably 80nm or less. The resist film is preferably a resist for electron beam lithography exposure, and the resist is more preferably a chemically amplified resist.

[ production sequence of mask blank ]

The mask blank 100 configured as described above is manufactured by the following procedure. First, the transparent substrate 1 is prepared. The end face and the main surface of the light-transmitting substrate 1 are polished to a predetermined surface roughness (for example, the root mean square roughness Rq is 0.2nm or less in the inner region of a quadrangle having a side of 1 μm), and then subjected to a predetermined cleaning treatment and drying treatment.

Next, the phase shift film 2 is formed on the transparent substrate 1 by sputtering. After the phase shift film 2 is formed, annealing treatment at a predetermined heating temperature is performed. Next, the light shielding film 3 is formed on the phase shift film 2 by sputtering. Then, the hard mask film 4 is formed on the light-shielding film 3 by sputtering. In the deposition of each layer by the sputtering method, a sputtering target containing a material constituting each layer at a predetermined composition ratio and a sputtering gas are used. Further, film formation using a mixed gas of a rare gas and a reactive gas as a sputtering gas is performed as necessary. Then, when the mask blank 100 has a resist film, the surface of the hard mask film 4 is subjected to hmds (hexamethyldisilazane) treatment as needed. Then, a resist film is formed on the surface of the hard mask film 4 subjected to HMDS treatment by a coating method such as a spin coating method, thereby completing the mask blank 100.

Method for manufacturing phase shift mask

Next, a method for manufacturing a phase shift mask (transfer mask) in the present embodiment will be described by taking as an example a method for manufacturing a halftone phase shift mask using the mask blank 100 having the configuration shown in fig. 1, with reference to fig. 2.

First, a resist film is formed on the hard mask film 4 of the mask blank 100 by a spin coating method. Next, the resist film is exposed by an electron beam to draw a first pattern (phase shift pattern) to be formed on the phase shift film 2. Then, the resist film is subjected to predetermined processes such as PEB (Post Exposure Bake) processing, development processing, Post Bake processing, and the like, and a first pattern (resist pattern 5a) is formed on the resist film (see fig. 2 (a)).

Next, dry etching of the hard mask film 4 is performed using a fluorine-based gas with the resist pattern 5a as a mask, and a first pattern (hard mask pattern 4a) is formed on the hard mask film 4 (see fig. 2 (b)). The resist pattern 5a is then removed. Here, the dry etching of the light-shielding film 3 may be performed in a state where the resist pattern 5a remains without being removed. In this case, the resist pattern 5a disappears during dry etching of the light-shielding film 3.

Next, high-bias etching using a chlorine-based gas containing oxygen is performed using the hard mask pattern 4a as a mask, and a first pattern (light-shielding pattern 3a) is formed on the light-shielding film 3 (see fig. 2 c). The dry etching of the light-shielding film 3 with the chlorine-based gas containing oxygen uses an etching gas having a higher mixing ratio of the chlorine-based gas than that used in the prior art. The mixing ratio of the chlorine-based gas containing oxygen in the dry etching of the light-shielding film 3 is preferably a chlorine-based gas: oxygen is more than 10: 1. more preferably 15 or more: 1. more preferably 20 or more: 1. by using an etching gas having a high mixing ratio of the chlorine-based gas, the anisotropy of dry etching can be improved. In the dry etching of the light-shielding film 3, the mixing ratio of the chlorine-based gas containing oxygen is preferably a chlorine-based gas: oxygen is 40 or less: 1.

in addition, in the dry etching of the light-shielding film 3 with a chlorine-based gas containing oxygen, the bias applied to the back surface side of the transparent substrate 1 is also higher than in the conventional case. Although there are differences in the effects of increasing the bias voltage according to the etching apparatus, the power when applying the bias voltage is, for example, preferably 15[ W ] or more, more preferably 20[ W ] or more, and still more preferably 30[ W ] or more. By increasing the bias voltage, the anisotropy of dry etching of the chlorine-based gas containing oxygen can be increased.

Next, dry etching using a fluorine-based gas is performed using the light-shielding pattern 3a as a mask to form a first pattern (phase shift pattern 2a) on the phase shift film 2 and remove the hard mask pattern 4a (see fig. 2 d).

Next, a resist film was formed on the light-shielding pattern 3a by spin coating. The resist film is exposed by an electron beam to draw a second pattern (light-shielding pattern) to be formed on the light-shielding film 3. Then, a predetermined process such as a development process is performed to form a resist film (resist pattern 6b) having a second pattern (light-shielding pattern) (see fig. 2 e).

Next, dry etching using a chlorine-based gas containing oxygen is performed using the resist pattern 6b as a mask, and a second pattern (light-shielding pattern 3b) is formed on the light-shielding film 3 (see fig. 2 (f)). The dry etching of the light-shielding film 3 at this time can be performed under conventional conditions with respect to the mixing ratio of the chlorine-based gas containing oxygen and the bias voltage.

The resist pattern 6b is further removed, and a predetermined process such as cleaning is performed to obtain a phase shift mask 200 (see fig. 2 g).

The chlorine-based gas used for the dry etching in the above-described production process is not particularly limited as long as it contains Cl. For example, the chlorine-based gas may be Cl₂、SiCl₂、CHCl₃、CH₂Cl₂、CCl₄、BCl₃And the like. In addition, the drying is performed in the above-mentioned manufacturing processThe fluorine-based gas used in the etching is not particularly limited as long as it contains F. For example, CHF is an example of the fluorine-based gas₃、CF₄、C₂F₆、C₄F₈、SF₆And the like. In particular, since the etching rate of the glass substrate by the fluorine-based gas containing no C is low, damage to the glass substrate can be further reduced.

The phase shift mask 200 manufactured by the above steps has a structure in which the phase shift pattern 2a and the light shielding pattern 3b are stacked on the transparent substrate 1 in this order from the transparent substrate 1 side.

In the above-described method for manufacturing a phase shift mask, the phase shift mask 200 is manufactured using the mask blank 100 described with reference to fig. 1. In the production of such a phase shift mask, dry etching using a chlorine-based gas containing oxygen, which tends to be isotropic, is applied to the step of fig. 2(c), which is a step of dry etching for forming a phase shift pattern (a fine pattern to be formed on the phase shift film 2) on the light-shielding film 3. The dry etching with the oxygen-containing chlorine-based gas in the step of fig. 2(c) is performed under high-bias etching conditions in which the ratio of the chlorine-based gas in the oxygen-containing chlorine-based gas is high. This can improve the anisotropy of etching while suppressing a decrease in the etching rate in the dry etching step of the light-shielding film 3. This reduces lateral etching when forming the phase shift pattern on the light-shielding film 3.

In addition, in the present invention, by applying the hard mask film 4 having excellent performance suitable for the high bias etching conditions, it is possible to further miniaturize the pattern to be formed on the hard mask film 4 and to improve the pattern quality. As a result, the pattern to be formed on the light-shielding film 3 can be further miniaturized and the pattern quality can be improved.

Further, lateral etching of the light-shielding film 3 is reduced, and further miniaturization of the pattern to be formed on the light-shielding film 3 and improvement of the pattern quality are achieved, and the phase shift pattern 2a can be formed with high accuracy by dry etching the phase shift film 2 with a fluorine-based gas using the light-shielding pattern 3a having a phase shift pattern formed with high accuracy as an etching mask. By the above operation, the phase shift mask 200 with high pattern accuracy can be manufactured.

Method for manufacturing semiconductor device

Next, a method for manufacturing a semiconductor device using the phase shift mask manufactured by the above-described manufacturing method as a transfer mask will be described. The manufacturing method of the semiconductor device has the following characteristics: the transfer pattern (phase shift pattern 2a) of the phase shift mask 200 is transferred by exposure to a resist film on the substrate using the halftone type phase shift mask 200 produced by the above-described production method. The method of manufacturing such a semiconductor device is performed as follows.

First, a substrate on which a semiconductor device is formed is prepared. The substrate may be, for example, a semiconductor substrate, a substrate having a semiconductor thin film, or a microfabricated film may be further formed on the substrate. Then, a resist film is formed on the prepared substrate, and pattern exposure is performed on the resist film using the halftone-type phase shift mask 200 manufactured by the above-described manufacturing method. Thereby, the transfer pattern formed on the phase shift mask 200 is exposed and transferred to the resist film. At this time, as the exposure light, exposure light corresponding to the phase shift film 2 constituting the transfer pattern is used, and here, for example, ArF excimer laser is used.

The resist film after exposure and transfer of the transfer pattern is subjected to a developing process to form a resist pattern, and the surface layer of the substrate is subjected to an etching process using the resist pattern as a mask to perform a process of introducing impurities. After the treatment is completed, the resist pattern is removed. The above-described process is repeated on the substrate while replacing the transfer mask, and necessary processing is further performed, thereby completing the semiconductor device.

In the manufacture of the semiconductor device as described above, by using the halftone-type phase shift mask manufactured by the above-described manufacturing method as a transfer mask, a resist pattern can be formed on a substrate with a precision that sufficiently satisfies the initial design specifications. Therefore, when the circuit pattern is formed by dry etching of the underlayer film under the resist film using the pattern of the resist film as a mask, a high-precision circuit pattern free from short-circuiting or disconnection of the wiring due to insufficient precision can be formed.

< second embodiment >

[ mask blank and production thereof ]

The mask blank according to the second embodiment of the present invention is a mask blank for manufacturing a binary mask (transfer mask) in which a thin film for pattern formation is a light-shielding film. However, the mask blank of the second embodiment may also be used as a mask blank for manufacturing a Phase shift mask of a cut-in Levenson type, or a CPL (chrome free Phase Lithography) mask.

The mask blank according to the second embodiment of the present invention is the mask blank according to the first embodiment described with reference to fig. 1, from which the phase shift film 2 has been removed. However, the light-shielding film 3 of this second embodiment is required to satisfy the Optical Density (OD) required in the laminated structure of the phase shift film 2 and the light-shielding film 3 of the first embodiment only by the light-shielding film 3.

The method for manufacturing a mask blank according to the second embodiment of the present invention is a method in which the phase shift film 2 is removed from the mask blank according to the first embodiment after the manufacturing step and the processing step (etching step).

In the mask blank according to the second embodiment of the present invention, all configurations of the substrate 1, the light-shielding film 3, the hard mask film 4, and the like are the same as all configurations described for the mask blank according to the first embodiment.

< third embodiment >

[ mask blank and production thereof ]

The mask blank according to the third embodiment of the present invention is a mask blank for manufacturing a reflective mask (transfer mask) in which a thin film for pattern formation is an absorber film (including a case where the thin film functions as a phase shift film having a phase shift function).

Fig. 6 is a schematic view for explaining the structure of the reflective mask blank of the present invention. As shown in fig. 6, the reflective mask blank 300 includes: a substrate 11, a multilayer reflective film 12, a protective film 13, an absorber film 14 that absorbs euv (extreme Ultra violet) light, and a hard mask film (etching mask) 15, which is a hard mask for etching, are sequentially laminated. The multilayer reflective film 12 is formed on the first main surface (front surface) side, and reflects EUV light as exposure light. The protective film 13 is provided to protect the multilayer reflective film 12. The protective film 13 is formed of an etchant used for patterning the absorber film 14 described later and a material having resistance to a cleaning solution. The hard mask film 15 serves as a mask when etching the absorber film 14. A back conductive film 16 for an electrostatic chuck is usually formed on the second main surface (back surface) side of the substrate 11.

Hereinafter, each layer will be described.

[ base plate ]

As the substrate 11, in order to prevent distortion of the absorber pattern caused by heat when exposure is performed with EUV light, it is preferable to use a raw material having a low thermal expansion coefficient in the range of 0 ± 5ppb/° c. As a raw material having a low thermal expansion coefficient in this range, for example: SiO 2₂-TiO₂Glass-like, multicomponent glass-ceramic, and the like.

[ multilayer reflective film ]

The multilayer reflective film 12 is provided with a function of reflecting EUV light in a reflective mask 400 (fig. 7(e)) described later. The multilayer reflective film 12 has a structure of a multilayer film in which layers containing elements having different refractive indices as main components are periodically stacked.

Generally, as the multilayer reflective film 12, a multilayer film in which a thin film of a light element or a compound thereof (high refractive index layer) as a high refractive index material and a thin film of a heavy element or a compound thereof (low refractive index layer) as a low refractive index material are alternately laminated for about 40 to 60 cycles is used. The multilayer film may be formed by laminating a plurality of periods as 1 period, in a laminated structure of a high refractive index layer/a low refractive index layer in which a high refractive index layer and a low refractive index layer are laminated in this order from the substrate 11 side, or may be formed by laminating a plurality of periods as 1 period, in a laminated structure of a low refractive index layer/a high refractive index layer in which a low refractive index layer and a high refractive index layer are laminated in this order from the substrate 11 side. The outermost layer of the multilayer reflective film 12 (i.e., the surface layer of the multilayer reflective film 12 on the side opposite to the substrate 11) is preferably a high refractive index layer. In the multilayer film described above, when a laminated structure (high refractive index layer/low refractive index layer) in which a high refractive index layer and a low refractive index layer are laminated in this order on the substrate 11 is laminated for a plurality of cycles as 1 cycle, the uppermost layer becomes the low refractive index layer. The low refractive index layer on the outermost surface of the multilayer reflective film 12 is easily oxidized, and thus the reflectance of the multilayer reflective film 12 decreases. In order to avoid a decrease in reflectance, it is preferable to form the multilayer reflective film 12 by further forming a high refractive index layer on the uppermost low refractive index layer. On the other hand, in the multilayer film described above, when a multilayer structure (low refractive index layer/high refractive index layer) in which a low refractive index layer and a high refractive index layer are sequentially laminated on the substrate 11 is formed in a plurality of cycles by 1 cycle, the uppermost layer is a high refractive index layer. In this case, it is not necessary to further form a high refractive index layer.

In the third embodiment, a layer containing silicon (Si) is used as the high refractive index layer. As the Si-containing material, in addition to the simple substance Si, an Si compound containing boron (B), carbon (C), nitrogen (N), and/or oxygen (O) in Si can be used. By using a layer containing Si as the high refractive index layer, the reflective mask 400 for EUV lithography excellent in reflectivity of EUV light can be obtained. In the third embodiment, a glass substrate is preferably used as the substrate 11. Si is also excellent in adhesion to a glass substrate. As the low refractive index layer, a simple metal selected from molybdenum (Mo), ruthenium (Ru), rhodium (Rh), and platinum (Pt), or an alloy thereof can be used. For example, as the multilayer reflective film 12 for EUV light having a wavelength of 13nm to 14nm, a Mo/Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 to 60 periods is preferably used. The high refractive index layer as the uppermost layer of the multilayer reflective film 12 may be formed of silicon (Si), and a silicon oxide layer containing silicon and oxygen may be formed between the uppermost layer (Si) and the Ru-based protective film 13. By forming the silicon oxide layer, the cleaning resistance of the reflective mask 400 can be improved.

Methods of forming the multilayer reflective film 12 are well known in the art. Each layer of the multilayer reflective film 12 can be formed by, for example, ion beam sputtering. In the case of the Mo/Si periodic multilayer film described above, for example, an Si film having a thickness of about 4nm is first formed on the substrate 11 using an Si target by an ion beam sputtering method, and then an Mo film having a thickness of about 3nm is formed using an Mo target. The multilayer reflective film 12 is formed by laminating the Si film/Mo film for 40 to 60 cycles as 1 cycle. The outermost layer of the multilayer reflective film 12 is preferably an Si layer.

[ protective film ]

The protective film 13 is formed on the multilayer reflective film 12 to protect the multilayer reflective film 12 from dry etching and cleaning in the manufacturing process of the reflective mask 400 (fig. 7(e)) described later. In addition, the protective film 13 can protect the multilayer reflective film 12 when performing black defect correction using a phase shift pattern of an Electron Beam (EB). The protective film 13 may have a single-layer or multilayer laminated structure of two or more layers. As the material of the protective film 13, a material containing ruthenium (Ru) as a main component, for example, a Ru metal simple substance, or a Ru alloy containing Ru and at least one metal such as titanium (Ti), niobium (Nb), molybdenum (Mo), zirconium (Zr), yttrium (Y), boron (B), lanthanum (La), cobalt (Co), or rhenium (Re) can be used.

The material of the protective film 13 may further contain nitrogen. Among these materials, a Ru-based protective film containing Ti is particularly preferable. In the case of using the Ru-based protective film containing Ti, diffusion of silicon which is a constituent element of the multilayer reflective film from the surface of the multilayer reflective film 12 to the Ru-based protective film becomes small. Therefore, the surface roughness during mask cleaning is reduced, and the film is less likely to be peeled off. The reduction of the surface roughness is directly related to preventing the reduction of the reflectivity to the EUV exposure light. Therefore, reduction of surface roughness is important for improvement of exposure efficiency of EUV exposure and improvement of throughput. In the case of the protective film 13 having a multilayer laminated structure, the lowermost layer and the uppermost layer are formed of the above-described material containing Ru, and a metal other than Ru or an alloy is interposed between the lowermost layer and the uppermost layer.

The thickness of the protective film 13 is not particularly limited as long as the protective film 13 can function as the protective film 13. The thickness of the protective film 13 is preferably 1.0nm to 8.0nm, and more preferably 1.5nm to 6.0nm, from the viewpoint of the reflectivity of EUV light.

As a method for forming the protective film 13, a known film forming method can be used without particular limitation. Specific examples of the method for forming the protective film 13 include a sputtering method and an ion beam sputtering method.

[ absorbent film ]

An absorber film 14 for absorbing EUV light is formed on the protective film 13. As a material of the absorber film 14, a material which has a function of absorbing EUV light and can be processed by dry etching using a chlorine-based gas containing oxygen or a chlorine-based gas containing no oxygen can be used. In the case of patterning by dry etching using a chlorine-based gas containing oxygen, examples of suitable materials for the absorber film 14 include: a material containing chromium (Cr) is used as a material for forming the light-shielding film 3 of the first embodiment. On the other hand, in the case of forming a pattern by dry etching using a chlorine-based gas containing no oxygen, examples of suitable materials for the absorber film 14 include: a material containing tantalum (Ta), a material containing nickel (Ni), and a material containing cobalt (Co).

As the material containing tantalum (Ta) forming the absorber film 14, in addition to tantalum metal, a Ta-based material in which tantalum contains one or more elements selected from nitrogen, oxygen, boron, and carbon can be cited. Examples thereof include: ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, TaBOCN, and the like. In addition, as a material for forming the absorber film 14, a TaTi-based material containing tantalum (Ta) and titanium (Ti) may be applied. Examples of such a tai-based material include a tai alloy and a tai compound in which the tai alloy contains at least one of oxygen, nitrogen, carbon, and boron. Examples of the TaTi compound include: TaTiN, TaTiO, TaTiON, TaTiCON, TaTiB, TaTiBN, TaTiBO, TaTiBON, TaTiBCON, and the like.

As a material containing nickel (Ni) forming the absorber film 14, a nickel (Ni) simple substance or a nickel compound containing Ni as a main component is used. Ni has a higher extinction coefficient in EUV light than Ta, and is a material that can be dry-etched with a chlorine (Cl) gas. The refractive index n of Ni at a wavelength of 13.5nm is about 0.948 and the extinction coefficient k is about 0.073. In contrast, in the case of TaBN, which is an example of a conventional material for an absorber film, the refractive index n is about 0.949 and the extinction coefficient k is about 0.030.

Examples of the nickel compound include compounds in which at least one of boron (B), carbon (C), nitrogen (N), oxygen (O), phosphorus (P), titanium (Ti), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), tellurium (Te), palladium (Pd), tantalum (Ta), and tungsten (W) is added to nickel. By adding these elements to nickel, the etching rate can be increased, the workability can be improved, and the cleaning resistance can be improved. The Ni content of these nickel compounds is preferably 50 at% or more and less than 100 at%, more preferably 80 at% or more and less than 100 at%.

On the other hand, by configuring the absorber film 14 to contain at least one of cobalt (Co) and nickel (Ni), the extinction coefficient k can be set to 0.035 or more, and the absorber film can be made thin. Further, by using the absorber film 14 as an amorphous metal, the etching rate can be increased, the pattern shape can be made good, and the processing characteristics can be improved. The amorphous metal may be a material in which at least one or more elements (X) selected from tungsten (W), niobium (Nb), tantalum (Ta), titanium (Ti), zirconium (Zr), hafnium (Hf), yttrium (Y), and phosphorus (P) is added to at least one or more elements selected from cobalt (Co) and nickel (Ni).

The absorber film 14 can be formed by a known method, for example, a magnetron sputtering method such as a DC sputtering method or an RF sputtering method.

The absorber film 14 may be an absorber film for absorbing EUV light used for the binary reflective mask blank 300. The absorber film 14 may be an absorber film (phase shift film) used for the phase shift type reflective mask blank 300 and having a phase shift function in consideration of the phase difference of EUV light.

In the case of the absorber film 14 for absorbing EUV light, the film thickness is set so that the reflectivity of EUV light to the absorber film 14 becomes 2% or less.

In the case of the absorber film 14 having a phase shift function, the EUV light is absorbed and attenuated in the portion where the absorber film 14 is formed, and part of the light is reflected at a level that does not adversely affect the pattern transfer. On the other hand, the reflected light from the field portion where the absorber film 14 is not formed is reflected from the multilayer reflective film 12 via the protective film 13. The absorber film 14 having a phase shift function can form a desired phase difference between the reflected light from the portion where the absorber film 14 is formed and the reflected light from the field portion. The absorber film 14 is formed so that the phase difference between the reflected light from the absorber film 14 and the reflected light from the multilayer reflective film 12 (field portion) is 160 degrees (°) to 200 degrees. The light beams with the phase difference reversed by about 180 degrees interfere with each other at the edge of the pattern, thereby improving the image contrast of the projected optical image. As the image contrast is improved, the resolution is increased, and various tolerances related to exposure, such as exposure tolerance and focus tolerance, can be expanded. Although it depends on the pattern and the exposure conditions, the reflectance standard for obtaining the phase shift effect is generally 1% or more in terms of absolute reflectance and 2% or more in terms of reflectance to the multilayer reflective film 12 (with the protective film 13).

The absorber film 14 can be a single layer film. The absorber film 14 may be a multilayer film composed of two or more layers. When the absorber film 14 is a single-layer film, the number of steps in manufacturing a mask blank can be reduced, thereby improving the production efficiency. When the absorber film 14 is a multilayer film, the optical constants and the film thickness thereof may be appropriately set so that the upper layer film becomes an antireflection film for mask pattern inspection using light. This can improve the inspection sensitivity when the mask pattern is inspected by light. In this way, various functions can be added to the absorber film 14 by using the absorber film 14 of the multilayer film. When the absorber film 14 is the absorber film 14 having the phase shift function, the use of the absorber film 14 having a multilayer film makes it possible to widen the range of adjustment of the optical surface, and to easily obtain a desired reflectance. Further, as a part (uppermost layer) of the absorber film 14 of the multilayer film, a mode using the hard mask film 15 of the present invention described later may be adopted.

An oxide layer is preferably formed on the surface of the absorber film 14 of nickel compound. By forming the oxide layer of the nickel compound, the resistance to cleaning of the absorber pattern 14a (fig. 7(e)) of the obtained reflective mask 400 can be improved. The thickness of the oxide layer is preferably 1.0nm or more, more preferably 1.5nm or more. The thickness of the oxide layer is preferably 5nm or less, more preferably 3nm or less. If the thickness of the oxide layer is less than 1.0nm, the oxide layer is too thin to expect an effect, and if it exceeds 5nm, the influence on the surface reflectance of the mask inspection light becomes large, and it becomes difficult to perform control for obtaining a predetermined surface reflectance.

Examples of the method for forming the oxide layer of the nickel compound include a method in which a mask blank on which the absorber film is formed is subjected to a hot water treatment, an ozone water treatment, a heating treatment in an oxygen-containing gas, an ultraviolet irradiation treatment in an oxygen-containing gas, and O₂Plasma treatment, etc.

[ hard mask film ]

A hard mask film 15 is formed on the absorber film 14. The material, film thickness, and the like of the hard mask film 15 are all the same as those of the hard mask film 4 described in the first embodiment.

Ni has a lower dry etching rate with chlorine-based gas than Ta. Therefore, if it is desired to directly form the resist film 17 on the absorber film 14 made of a material containing Ni, the resist film 17 must be thickened, and it is difficult to form a fine pattern. On the other hand, by forming the hard mask film 15 made of a material containing Si on the absorber film 14, the absorber film 14 can be etched without increasing the thickness of the resist film 17. Therefore, by using the hard mask film 15, a fine absorber pattern 14a can be formed.

In addition, the hard mask film 15 made of a material containing silicon, oxygen, and nitrogen according to the present invention has more excellent performance than the conventional hard mask film. In the present invention, by applying the hard mask 15 having excellent performance suitable for the high bias etching conditions, it is possible to further miniaturize the pattern to be formed on the hard mask film 15 and to improve the pattern quality. As a result, the pattern to be formed on the absorber film 14 can be further miniaturized and the pattern quality can be improved.

The hard mask film 15 is preferably 2nm or more in film thickness from the viewpoint of obtaining a function as an etching mask for forming a transfer pattern on the absorber film 14 with good accuracy. In addition, the hard mask film 15 has a film thickness of preferably 20nm or less, more preferably 15nm or less, from the viewpoint of reducing the film thickness of the resist film 17.

[ Back surface conductive film ]

Generally, a back conductive film 16 for an electrostatic chuck is formed on the second main surface (back surface) side of the substrate 11 (the opposite side to the surface on which the multilayer reflective film 12 is formed). The electrical characteristics required for the back conductive film 16 for an electrostatic chuck are generally 100 Ω/square or less. The back conductive film 16 can be formed by using a target of metal such as chromium or tantalum or an alloy thereof by, for example, magnetron sputtering or ion beam sputtering. Typical materials of the back conductive film 16 are CrN and Cr which are commonly used for manufacturing mask blanks such as light transmissive mask blanks. The thickness of the back conductive film 16 is not particularly limited as long as it satisfies the function as an electrostatic chuck, and is usually 10nm to 200 nm. The back conductive film 16 also serves to adjust the stress on the second main surface side of the mask blank 300. The back conductive film 16 can be adjusted so as to balance the stress from the various films formed on the first main surface side, thereby obtaining a flat reflective mask blank 300.

Reflective mask and method for manufacturing the same

The reflective mask blank 300 (fig. 6) of the third embodiment can be used to manufacture a reflective mask 400. An example thereof will be described below with reference to fig. 7.

A reflective mask blank 300 is prepared, and a resist film 17 is formed on the hard mask film 15 on the first main surface thereof (which is not required in the case where the reflective mask blank 300 is provided with the resist film 17) (fig. 7 (a)).

Next, a desired pattern is drawn (exposed) on the resist film 17, and further developed and rinsed, thereby forming a predetermined resist pattern 17a (fig. 7 (b)).

When the reflective mask blank 300 is used, first, the hard mask film 15 is etched using the above-described resist pattern 17a as a mask to form an etching mask pattern 15a (fig. 7 c).

Next, the resist pattern 17a is removed by ashing, a resist stripping solution, or the like. Then, dry etching is performed using the etching mask pattern 15a as a mask, whereby the absorber film 14 is etched to form an absorber pattern 14a (fig. 7 d).

Then, the etching mask pattern 15a is removed by dry etching (fig. 7 (e)). Finally, at least one of washing with an acidic aqueous solution and washing with a basic aqueous solution is performed.

When the hard mask film 15 is formed of a material containing silicon (Si), CF may be used as an etching gas for forming the pattern of the hard mask film 15 and removing the etching mask pattern 15a₄、CHF₃、C₂F₆、C₃F₆、C₄F₆、C₄F₈、CH₂F₂、CH₃F、C₃F₈、SF₆And F₂Equal fluorine-containing gas, He and H₂、N₂、Ar、C₂H₄And O₂And the like (they are collectively referred to as "fluorine-containing gas").

Examples of the etching gas for the absorber film 14 include: cl₂、SiCl₄、CHCl₃And CCl₄Chlorine-containing gas, a mixed gas containing chlorine-containing gas and He at a predetermined ratio, a mixed gas containing chlorine-containing gas and Ar at a predetermined ratio, and the like. In the etching of the absorber film 14, the etching gas does not substantially contain oxygen, and therefore, the Ru-based protective film does not have surface roughness. In the present specification, "the etching gas contains substantially no oxygen" means that the content of oxygen in the etching gas is 5 atomic% or less.

Note that, there is also a method of etching the absorber film 14 using the etching mask pattern 5a with the resist pattern 17a as a mask without removing the resist pattern 17a immediately after the etching mask pattern 15a is formed. In this case, the following features exist: when the absorber film 14 is etched, the resist pattern 17a is automatically removed, and the process is simplified. On the other hand, the following features exist: in the method of etching the absorber film 14 using the etching mask pattern 15a from which the resist pattern 17a has been removed as a mask, stable etching can be achieved without a change in organic products (exhaust gas) from the resist that disappears during etching.

Through the above steps, the reflective mask 400 having a fine pattern with a small side wall roughness and a small masking effect and high accuracy can be obtained.

Method for manufacturing semiconductor device

By performing EUV exposure using the reflective mask 400 of the present embodiment, a desired transfer pattern based on the absorber pattern 14a on the reflective mask 400 can be formed on the semiconductor substrate.

Examples

Hereinafter, embodiments of the present invention will be described more specifically by way of examples.

EXAMPLE 1

[ production of mask blank ]

Referring to fig. 1, a light-transmissive substrate 1 made of synthetic quartz glass having a main surface with dimensions of about 152mm × about 152mm and a thickness of about 6.35mm was prepared. The end face and the main surface of the light-transmitting substrate 1 were polished to a predetermined surface roughness (0.2 nm or less in Rq), and then subjected to a predetermined cleaning treatment and drying treatment.

Next, the translucent substrate 1 was set in a single-wafer DC sputtering apparatus, and argon (Ar) and nitrogen (N) were mixed by using a mixed sintering target of molybdenum (Mo) and silicon (Si) (Mo: Si 11 atomic%: 89 atomic%), and using a mixed sintering target of molybdenum (Mo) and silicon (Si)₂) And helium (He) as a sputtering gas, and a phase shift film 2 containing molybdenum, silicon, and nitrogen was formed on the transparent substrate 1 in a thickness of 69 nm.

Next, a heat treatment for reducing the film stress of the phase shift film 2 and for forming an oxide layer on the surface layer of the transparent substrate 1 on which the phase shift film 2 is formed is performed. Specifically, a heating treatment was performed in an atmosphere using a heating furnace (electric furnace) at a heating temperature of 450 ℃ for 1 hour. The transmittance and phase difference of the phase shift film 2 after the heat treatment with respect to light having a wavelength of 193nm were measured by using a phase shift amount measuring apparatus (MPM 193 manufactured by Lasertec corporation), and the transmittance was 6.0% and the phase difference was 177.0 degrees (°).

Next, the translucent substrate 1 on which the phase shift film 2 was formed was set in a single-wafer DC sputtering apparatus, and argon (Ar) and carbon dioxide (CO) were added using a chromium (Cr) target₂) Nitrogen (N)₂) And helium (He) in a mixed gas atmosphere. Thus, a light-shielding film (CrOCN film) 3 containing chromium, oxygen, carbon, and nitrogen was formed in contact with the phase shift film 2 to a film thickness of 43 nm.

Next, the light-transmitting substrate 1 on which the light-shielding film (CrOCN film) 3 is formed is subjected to heat treatment. Specifically, a heating treatment was performed using a hot plate at a heating temperature of 280 ℃ for 5 minutes in the air. After the heat treatment, the optical density of the laminated structure of the phase shift film 2 and the light-shielding film 3 at the wavelength of ArF excimer laser light (about 193nm) was measured with a spectrophotometer (Cary 4000, manufactured by Agilent Technologies) for the light-transmitting substrate 1 on which the phase shift film 2 and the light-shielding film 3 were laminated, and was confirmed to be 3.0 or more.

Next, a translucent substrate 1 on which a phase shift film 2 and a light-shielding film 3 are laminated is provided in a single-wafer DC sputtering apparatus, and argon (Ar) and oxygen (O) are introduced using a silicon (Si) target₂) And nitrogen (N)₂) A hard mask film 4 containing silicon, oxygen, and nitrogen was formed on the light-shielding film 3 by DC sputtering using gas as a sputtering gas in a thickness of 15 nm. Further, a given cleaning process was performed, and a mask blank 100 of example 1 was manufactured.

A mask blank 100 in which a phase shift film 2, a light-shielding film 3, and a hard mask film 4 were formed on the main surface of the other transparent substrate 1 under the same conditions was prepared. The mask blank 100 was analyzed by X-ray photoelectron spectroscopy (XPS with RBS correction). As a result, the content of each constituent element of the hard mask film 4 was calculated as Si: 34 atomic%, O: 60 atomic%, N: 6 atom%.

The light-transmissive substrate 1, the phase shift film 2, the light-shielding film 3, and the hard mask film 4 of example 1 were analyzed by X-ray photoelectron spectroscopy, and the results of the analysis of the chemical bond state in the depth direction of the narrow spectrum of Si2p, the analysis of the chemical bond state in the depth direction of the narrow spectrum of N1s, and the analysis of the chemical bond state in the depth direction of the narrow spectrum of O1s, respectively, are shown in fig. 3, 4, and 5, respectively.

In the analysis of the hard mask film 4 by the X-ray photoelectron spectroscopy, the analysis in the film thickness direction was performed in the order of the hard mask film 4, the light-shielding film 3, the phase shift film 2, and the light-transmissive substrate 1 by repeating the steps of irradiating the surface of the mask blank 100 (the hard mask film 4) with X-rays, measuring the energy distribution of photoelectrons emitted from the hard mask film 4, digging into the hard mask film 4 for a predetermined time by Ar gas sputtering, irradiating the surface of the hard mask film 4 in the dug-in region with X-rays, and measuring the energy distribution of photoelectrons emitted from the hard mask film 4. In the analysis by the X-ray photoelectron spectroscopy, the X-ray source used was monochromated Al (1486.6eV), and the analysis was performed under conditions that the photoelectrons were detected in a region of 100. mu. m.phi. and at a depth of detection of about 4 to 5nm (extraction angle of 45 degrees (. degree.)))) (the same applies to other examples and comparative examples below).

In each of the depth direction chemical bond state analyses in fig. 3 to 5, the analysis result of the outermost surface of the hard mask film 4 before the Ar gas sputtering (sputtering time: 0min) is shown in a graph of "0.00 min", the analysis result of the position in the film thickness direction of the hard mask film 4 after the outermost surface of the hard mask film 4 has been dug in only 1.00min by the Ar gas sputtering is shown in a graph of "1.00 min", and the analysis result of the position in the film thickness direction of the hard mask film 4 after the outermost surface of the hard mask film 4 has been dug in only 4.00min by the Ar gas sputtering is shown in a graph of "4.00 min".

In the analysis of the chemical bond state in each depth direction in fig. 3 to 5, the analysis result of the position of the light shielding film 3 in the film thickness direction after the excavation of only 9.00min from the outermost surface of the hard mask film 4 by the Ar gas sputtering is shown in a graph of "9.00 min", and the analysis result of the position of the light shielding film 3 in the film thickness direction after the excavation of only 14.00min from the outermost surface of the hard mask film 4 by the Ar gas sputtering is shown in a graph of "14.00 min".

In the analysis of the chemical bond state in each depth direction in fig. 3 to 5, the analysis result of the position in the film thickness direction of the phase shift film 2 after the excavation of only 21.00min from the outermost surface of the hard mask film 4 by the Ar gas sputtering is shown in a graph of "21.00 min", the analysis result of the position in the film thickness direction of the phase shift film 2 after the excavation of only 26.00min from the outermost surface of the hard mask film 4 by the Ar gas sputtering is shown in a graph of "26.00 min", and the analysis result of the position in the film thickness direction of the phase shift film 2 after the excavation of only 30.00min from the outermost surface of the hard mask film 4 by the Ar gas sputtering is shown in a graph of "30.00 min".

The scale of the vertical axis of the graphs in each narrow spectrum of fig. 3-5 is different. In the narrow spectrum of Si2p of fig. 3, the scale of the vertical axis is greatly enlarged in each of the narrow spectra of "graph at 9.00 min" and "graph at 14.00 min" compared with the narrow spectra of the other graphs. That is, the vibration wave in each narrow spectrum of the "graph of 9.00 min" and the "graph of 14.00 min" of the narrow spectrum of Si2p of fig. 3 does not indicate the presence of a peak, but only noise. This result shows that the content of silicon is equal to or less than the detection lower limit at the position in the film thickness direction corresponding to each narrow spectrum of Si2p of the light-shielding film 3.

The analysis result of the position in the film thickness direction of the hard mask film 4 after digging only 1.00min from the outermost surface of the light-shielding film 3 by Ar gas sputtering was the measurement result of the portion other than the surface layer portion of the hard mask film 4.

From the results of the narrow Si2p spectrum of fig. 3, the hard mask film 4 of example 1 has the largest peak in the bond energy between 103 to 104 eV. This result means that Si-O bonds are present at a ratio of at least (SiO)₂As the main body).

It was found that there was almost no difference (less than 0.1eV) between the position of the bond energy at which the maximum peak was present in the narrow spectrum of Si2p on the outermost surface (0.00min) and the position of the bond energy at which the maximum peak was present in the narrow spectrum of Si2p inside the film (1.00 min). In this regard, it is found that it is preferable to obtain high controllability in the etching process of the hard mask film 4.

As is clear from the results of the Si2p narrow spectrum in fig. 3, the hard mask film 4 of example 1 has a substantially flat bond energy between 97eV and 100eV, and has no peak. This result means that the presence of Si-Si bonds was not detected.

As is clear from the results of the narrow spectrum of N1s in FIG. 4, the hard mask film 4 of example 1 has a maximum peak of bond energy between 398 and 399 eV. This result means that Si-N bonds are present at a ratio or more.

It was found that there was no difference (less than 0.05eV) between the position of the bond energy at which the maximum peak was present in the N1s narrow spectrum on the outermost surface (0.00min) and the position of the bond energy at which the maximum peak was present in the N1s narrow spectrum inside the film (1.00 min). In this regard, it is found that it is preferable to obtain high controllability in etching of the hard mask film.

As is clear from the results of the narrow O1s spectrum of FIG. 5, the hard mask film 4 of example 1 has a maximum peak in the bond energy between 532-533 eV. This result means that Si-O bonds are present at a ratio or more.

It was found that there was almost no difference (less than 0.1eV) between the position of the bond energy at which the maximum peak was present in the narrow O1s spectrum on the outermost surface (0.00min) and the position of the bond energy at which the maximum peak was present in the narrow O1s spectrum inside the film (1.00 min). In this regard, it is found that it is preferable to obtain high controllability in etching of the hard mask film.

[ production of phase Shift mask ]

Next, using the mask blank 100 of example 1, the halftone-type phase shift mask 200 of example 1 was manufactured in the following procedure. First, HMDS treatment is performed on the surface of the hard mask film 4.

Next, the effect of HMDS treatment was evaluated using the contact angle of water. A large contact angle with water means high hydrophobicity. This means that the distortion of the resist pattern (the peeling of the resist pattern) caused by the intrusion of the developer or the rinse liquid into the interface of the film in contact with the resist pattern is suppressed. The water contact angle of the surface of the hard mask film 4 was measured at room temperature in an environment of 23 ℃ by using a full-automatic contact angle meter DM-701 (manufactured by synechia chemical corporation). The contact angle of the hard mask film 4 was measured as follows: each measurement point (9 × 9 points, which are 81 points in total) arranged at equal intervals in a grid pattern is performed on the inner area of a quadrangle having a side of 132mm with respect to the center of the substrate (the same applies to other examples and comparative examples below).

As a result, the average value of the contact angle of water measured at each measurement point was 59.7 degrees (°).

Then, a resist film made of a chemical amplification resist for electron beam lithography was formed by a spin coating method so as to contact the surface of the hard mask film 4 with a film thickness of 70nm (conventionally 80 nm). Next, a first pattern, which is a phase shift pattern to be formed on the phase shift film 2, is drawn by electron beam irradiation on the resist film, and a predetermined developing process and cleaning process are performed to form a resist pattern 5a having the first pattern (see fig. 2 (a)). The first pattern is a pattern (phase shift pattern) including a fine pattern (SRAF pattern or the like having a line width of 35nm or less (conventionally 40nm or less)) to be formed on the phase shift film 2. The resist pattern 5a formed on the hard mask film 4 was good in that no distortion of the resist pattern was observed.

Next, CF was used using the resist pattern 5a as a mask₄The first pattern (hard mask pattern 4a) is formed on the hard mask film 4 by dry etching with gas (see fig. 2 (b)).

The hard mask pattern 4a was observed with a Scanning Electron Microscope (SEM), and as a result, the surface of the sidewall was smooth.

Next, the resist pattern 5a is removed. Next, using chlorine gas (Cl) was performed using the hard mask pattern 4a as a mask₂) With oxygen (O)₂) Mixed gas (gas flow rate ratio Cl)₂：O₂13: 1) dry etching (power at bias application of 50[ W ]]High-bias etching) of (b), a first pattern (light-shielding pattern 3a) is formed on the light-shielding film 3 (see fig. 2 (c)). The etching time (total etching time) of the light-shielding film 3 is 1.5 times the time (appropriate etching time) from the start of etching of the light-shielding film 3 to the initial exposure of the surface of the phase shift film 2. That is, overetching is performed by adding only 50% of the proper etching time (overetching time). By performing the over-etching, the verticality of the pattern sidewall of the light-shielding film 3 can be improved.

When the hard mask pattern 4a after the over-etching was observed with a Scanning Electron Microscope (SEM), the edge between the side wall of the pattern and the surface (the surface on the side opposite to the bottom surface of the pattern (the upper surface of the pattern)) was sharp (the angle was not rounded). In addition, the surface of the sidewall of the hard mask pattern 4a is smooth.

Next, using fluorine-based gas (SF) with the light-shielding pattern 3a as a mask, a process of forming a pattern using fluorine-based gas (SF) is performed₆+ He) forms the first pattern (phase shift pattern 2a) on the phase shift film 2 and removes the hard mask pattern 4a at the same time (see fig. 2 d).

Next, a resist film made of a chemical amplification resist for electron beam lithography was formed on the light-shielding pattern 3a by spin coating with a film thickness of 150 nm. Next, a second pattern, which is a pattern to be formed on the light-shielding film (a pattern including a light-shielding belt pattern), is drawn against resist exposure, and a predetermined process such as a development process is further performed, thereby forming a resist pattern 6b having a light-shielding pattern (see fig. 2 (e)).

Next, using chlorine gas (Cl) was performed using the resist pattern 6b as a mask₂) With oxygen (O)₂) Mixed gas (gas flow rate ratio Cl)₂：O₂4: 1) the second pattern (light-shielding pattern 3b) is formed on the light-shielding film 3 by the dry etching (see fig. 2 (f)).

Further, the resist pattern 6b is removed and subjected to a predetermined process such as cleaning, thereby obtaining a phase shift mask 200 (see fig. 2 g).

As a result of performing defect inspection of the manufactured transfer mask 200 (halftone phase shift mask), no defect due to the distortion of the resist pattern was observed, and a transfer mask having few defects was confirmed. Since the number of defects is small, the production yield of the transfer mask is high.

[ evaluation of Pattern transfer Property ]

With respect to the phase shift mask 200 manufactured by the above procedure, a simulation of a transfer image when transferred to a resist film on a semiconductor device by exposure to exposure light having a wavelength of 193nm was performed using the AIMS193 (manufactured by Carl Zeiss). The simulated exposure transfer image was verified, and as a result, the design specifications were fully satisfied. From the results, it is understood that the phase shift mask 200 of embodiment 1 can form a circuit pattern on a semiconductor device with high accuracy in the end even if it is set on a mask stage of an exposure apparatus and exposed to a resist film transferred onto the semiconductor device.

Comparative example 1

[ production of mask blank ]

Comparative example 1 is the same as example 1 except for the film formation conditions of the hard mask film 4. Hereinafter, the differences from embodiment 1 will be described with reference to fig. 2.

A hard mask film 4 formed of an SiON film is formed on the light-shielding film 3. Specifically, a silicon (Si) target is used in the presence of argon (Ar) and oxygen (O)₂) Nitrogen (N)₂) And helium (He) in the mixed gas atmosphere, thereby forming a hard mask film 4 made of a SiON film with a thickness of 15nm on the light-shielding film 3. The composition of the SiON film formed was Si: o: n-37: 44: 19 (atomic%) and the composition was determined by XPS.

From the results of the narrow Si2p spectrum, the hard mask film 4 of comparative example 1 had the largest peak in the bond energy between 103 and 104 eV. This result means that Si-O bonds are present at a ratio of at least (SiO)₂As the main body).

In addition, the hard mask film 4 of comparative example 1 has a significant peak in the bond energy between 97 to 100eV, although it does not have a significant peak in the bond energy between 103 to 104 eV. This result means that the Si — Si bond is present in the hard mask film 4 of comparative example 1 at a certain ratio or more.

Further, it was found that there was a difference of about 0.4eV between the position of the bond energy at which the maximum peak was present in the narrow spectrum of Si2p on the outermost surface (0.00min) and the position of the bond energy at which the maximum peak was present in the narrow spectrum of Si2p inside the film (1.00 min).

From the results of the narrow spectrum of N1s, the hard mask film 4 of comparative example 1 had the largest peak of the bond energy between 398 and 399 eV. This result means that Si-N bonds are present at a ratio or more.

It was found that there was a difference of about 0.3eV between the position of the bond energy at which the maximum peak was present in the N1s narrow spectrum on the outermost surface (0.00min) and the position of the bond energy at which the maximum peak was present in the N1s narrow spectrum inside the film (1.00 min).

From the results of the narrow spectrum of O1s, the hard mask film 4 of comparative example 1 had the largest peak in the bond energy between 532 to 533 eV. This result means that Si-O bonds are present at a ratio or more.

It was found that there was a difference of about 0.3eV between the position of the bond energy at which the maximum peak was present in the narrow O1s spectrum on the outermost surface (0.00min) and the position of the bond energy at which the maximum peak was present in the narrow O1s spectrum inside the film (1.00 min).

[ production of phase Shift mask ]

Next, a halftone-type phase shift mask 200 was produced in the same manner as in example 1, using the mask blank 100 of comparative example 1. First, HMDS treatment is performed on the surface of the hard mask film 4.

The average value of the contact angle of water measured at each measurement point was 53.6 degrees.

Next, a resist pattern 5a having a first pattern was formed in the same manner as in example 1 (see fig. 2 (a)). The first pattern is a pattern (phase shift pattern) including a fine pattern (SRAF pattern or the like having a line width of 35nm or less (conventionally 40nm or less)) to be formed on the phase shift film 2. The resist pattern 5a formed on the hard mask film 4 was partially distorted in the surface on which the resist pattern was formed. As a result, the manufactured transfer mask becomes a mask having a pattern defect. This is considered to be due to the fact that the surface of the hard mask film 4 is relatively less hydrophobic (relatively less adhesion to resist). Since there is a defect, the production yield of the transfer mask is low accordingly.

When the hard mask pattern 4a after the over-etching was observed by a Scanning Electron Microscope (SEM), some angles of the edge between the sidewall and the surface (upper surface) of the pattern were curved.

Comparative example 2

[ production of mask blank ]

In comparative example 2, the mask blank and the transfer mask were manufactured by forming the hard mask film 4 using silicon oxide, and the same procedure as in example 1 was performed except for the material of the hard mask film 4 and the method for forming the hard mask film. The differences from example 1 will be described below.

According to the following examples1A phase shift film 2 and a light shielding film 3 are formed in the same order. Next, oxygen (O) is introduced using a silicon (Si) target₂) And argon (Ar) gas as a sputtering gas, sputtering was performed, whereby a hard mask film 4 formed of an SiO film with a thickness of 15nm was formed on the light-shielding film 3. The composition of the SiO film is Si: o38.5: 61.5 (atomic%) and the composition was determined by XPS.

From the results of the narrow spectrum of Si2p, the hard mask film 4 of comparative example 2 has the maximum peak of Si — O bond at the bond energy of less than 103eV, and has the maximum peak of Si — Si bond at the bond energy of 98 to 99eV (the area intensity is also the same). This result means that Si-O bonds are present in the same degree of proportion as Si-Si bonds.

[ production of phase Shift mask ]

Next, a halftone-type phase shift mask 200 was produced in the same manner as in example 1, using the mask blank 100 of comparative example 2. First, HMDS treatment is performed on the surface of the hard mask film 4.

The average value of the contact angle of water measured at each measurement point was 49.7 degrees.

Next, a resist pattern 5a having a first pattern was formed in the same manner as in example 1 (see fig. 2 (a)). The first pattern is a pattern (phase shift pattern) including a fine pattern (SRAF pattern or the like having a line width of 35nm or less (conventionally 40nm or less)) to be formed on the phase shift film 2. The resist pattern 5a formed on the hard mask film 4 was partially distorted in the surface on which the resist pattern was formed. As a result, the manufactured transfer mask becomes a mask having a pattern defect. This is considered to be due to the fact that the surface of the hard mask film 4 is relatively less hydrophobic (relatively less adhesion to resist). Due to the presence of defects, the production yield of the transfer mask is correspondingly low.

When the hard mask pattern 4a immediately after formation was observed with a Scanning Electron Microscope (SEM), it was found that the line edge roughness of the sidewall was poor and the controllability of the etching process with respect to the fluorine-based gas was poor. Therefore, it is found that the etching processing accuracy of the hard mask film is poor, and the pattern transfer performance is inevitably lowered.

Further, it is found that when the hard mask pattern 4a after the light shielding film 3 is formed is observed with a Scanning Electron Microscope (SEM), the function as a hard mask tends to be significantly deteriorated (the etching resistance against chlorine-based gas is significantly deteriorated). Therefore, it is known that the degradation of the pattern transfer performance is inevitable.

While the embodiments and examples of the present invention have been specifically described, the technical scope of the present invention is not limited to the embodiments and examples described above, and various modifications can be made without departing from the scope of the present invention.