Photomask, method of correcting photomask, method of manufacturing photomask, and method of manufacturing device for display device
阅读说明：本技术 光掩模、其修正方法、制造方法、显示装置用器件的制造方法 (Photomask, method of correcting photomask, method of manufacturing photomask, and method of manufacturing device for display device ) 是由 中山憲治 于 2019-07-29 设计创作，主要内容包括：提供光掩模、其修正方法、制造方法、显示装置用器件的制造方法。即使在利用相移作用的光掩模中产生缺陷,也能够进行精密的修正。一种光掩模修正方法,对具有在透明基板(1)上将半透光膜(2)图案化而形成的转印用图案的光掩模中产生的缺陷(20)进行修正,包括确定缺陷(20)的工序；形成修正膜(4)的修正膜形成工序。半透光部(12)具有对于曝光光的代表波长的光的透射率Tm(％)(Tm＞25)和相移量φm(度)(160≤φm≤200)。在修正膜形成工序,按任意的顺序层叠组成彼此不同的第1膜4a和第2膜4b。第1膜4a包含Cr及O,第2膜4b包含Cr、O及C。第1膜不包含C,或包含含量小于第2膜的含量的C,第2膜包含含量小于第1膜的含量的O。(A photomask, a correction method thereof, a manufacturing method thereof, and a manufacturing method of a device for a display device are provided. Even if a defect occurs in a photomask using a phase shift effect, precise correction can be performed. A photomask correction method for correcting a defect (20) generated in a photomask having a transfer pattern formed by patterning a semi-transparent film (2) on a transparent substrate (1), includes a step of determining the defect (20); and a correction film forming step of forming a correction film (4). The semi-light transmitting part (12) has a transmittance Tm (%) for light of a representative wavelength of exposure light (Tm > 25) and a phase shift amount phi m (degrees) (160 < phi m < 200). In the correction film forming step, the 1 st film 4a and the 2 nd film 4b having different compositions are laminated in an arbitrary order. The 1 st film 4a contains Cr and O, and the 2 nd film 4b contains Cr, O and C. The 1 st film contains no C or C in an amount less than that of the 2 nd film, and the 2 nd film contains O in an amount less than that of the 1 st film.)
1. A photomask correction method for correcting a defect generated in a photomask having a transfer pattern including a semi-transparent portion formed by patterning a semi-transparent film on a transparent substrate, the photomask correction method comprising:
a step of determining the defect to be corrected; and
a correction film forming step of forming a correction film for correcting the defect,
the semi-light transmitting section has a transmittance Tm (%) for light of a representative wavelength of exposure light and a phase shift amount φ m (degrees), wherein φ m is 160 or more and 200 or less,
in the correction film forming step, a 1 st film and a 2 nd film having different compositions are laminated in an arbitrary order,
the 1 st film contains Cr and O,
the 2 nd film contains Cr, O, and C,
the 1 st film contains no C, or contains C in an amount less than that of the 2 nd film,
the 2 nd film contains O in an amount less than that of the 1 st film.
2. The method of claim 1, wherein the mask correction is performed,
Tm＞25。
3. the method of claim 1, wherein the mask correction is performed,
the correction film has a transmittance Tr (%) and a phase shift amount phi r (degree) for light of the representative wavelength satisfying 30 < Tr < 75 and 160 < phi r < 200.
4. The method of claim 1, wherein the mask correction is performed,
in the correction film formation step, a laser CVD method is applied.
5. The method of claim 1, wherein the mask correction is performed,
the transmittance T1 (%) and the amount of phase shift Φ 1 (degrees) of the 1 st film with respect to the light of the representative wavelength, and the transmittance T2 (%) and the amount of phase shift Φ 2 (degrees) of the 2 nd film with respect to the light of the representative wavelength satisfy the following relationships (1) to (4), respectively:
(1)100≤φ1＜200
(2)φ2＜100
(3)55≤T1
(4)25＜T2＜80。
6. the method of claim 5, wherein the mask correction is performed,
the Cr content contained in the 2 nd film is larger than that contained in the 1 st film.
7. The method of claim 5, wherein the mask correction is performed,
the total content of Cr and O contained in the 1 st film is 80% or more of the composition of the 1 st film in terms of atomic%.
8. The method of claim 5, wherein the mask correction is performed,
the 1 st film is composed of a material containing 5 to 45 atomic% of Cr and 55 to 95 atomic% of O,
the 2 nd film is composed of a material containing 20 to 70 atomic% of Cr, 5 to 45 atomic% of O, and 10 to 60 atomic% of C.
9. The method of claim 5, wherein the mask correction is performed,
laminating the 2 nd film on the 1 st film.
10. The method of claim 1, wherein the mask correction is performed,
the transfer pattern includes a light shielding portion that does not substantially transmit exposure light.
11. The method of claim 1, wherein the mask correction is performed,
the transfer pattern includes a light shielding portion that does not substantially transmit exposure light, and the semi-transmissive portion is disposed so as to be sandwiched by the light shielding portion.
12. The method of claim 1, wherein the mask correction is performed,
the correction film forming step is followed by a post-stage step of forming a supplementary film having a light-shielding property to modify the shape of the correction translucent portion on which the correction film is formed.
13. The method of claim 1, wherein the mask correction is performed,
the method further includes a pretreatment step of removing a film at or around the defect to expose the transparent substrate, prior to the correction film forming step.
14. The method of claim 1, wherein the mask correction is performed,
the photomask is used for manufacturing a device for a display device.
15. A method of manufacturing a photomask, the method comprising:
the photomask correction method of any one of claims 1 to 14.
16. A photomask having a transfer pattern including a semi-transmissive portion formed by patterning a semi-transmissive film formed on a transparent substrate, the photomask having a correction film formed on a defective portion generated in the semi-transmissive portion,
the semi-light-transmitting section has a transmittance Tm (%) and a phase shift amount φ m (degrees) for light of a representative wavelength of exposure light, wherein Tm > 25, 160 ≦ φ m ≦ 200,
the correction film has a laminated film obtained by laminating a 1 st film containing Cr and O and a 2 nd film containing Cr, C and O in an arbitrary order,
the 1 st film contains no C, or contains C in an amount less than that of the 2 nd film,
the 2 nd film contains O in an amount less than that of the 1 st film.
17. The photomask of claim 16,
the correction film has a transmittance Tr (%) and a phase shift amount phi r (degree) for light of the representative wavelength satisfying 30 < Tr < 75 and 160 < phi r < 200.
18. The photomask of claim 16,
the correction film is a laser CVD film.
19. The photomask of claim 16,
the transmittance T1 (%) and the amount of phase shift Φ 1 (degrees) of the 1 st film with respect to the light of the representative wavelength, and the transmittance T2 (%) and the amount of phase shift Φ 2 (degrees) of the 2 nd film with respect to the light of the representative wavelength satisfy the following relationships (1) to (4), respectively:
(1)100≤φ1＜200
(2)φ2＜100
(3)55≤T1
(4)25＜T2＜80。
20. the photomask of claim 19,
the 1 st film and the 2 nd film each contain Cr, and the content of Cr contained in the 2 nd film is larger than the content of Cr contained in the 1 st film.
21. The photomask of claim 19,
the total content of Cr and O contained in the 1 st film is 80% or more of the composition of the 1 st film in terms of atomic%.
22. The photomask of claim 19,
the 1 st film is composed of a material containing 5 to 45 atomic% of Cr and 55 to 95 atomic% of O,
the 2 nd film is composed of a material containing 20 to 70 atomic% of Cr, 5 to 45 atomic% of O, and 10 to 60 atomic% of C.
23. The photomask of claim 16,
the 2 nd film is laminated on the 1 st film.
24. The photomask of claim 16,
the transfer pattern has a light-shielding portion formed by patterning a light-shielding film formed on the transparent substrate.
25. The photomask of claim 16,
the transfer pattern includes a light shielding portion that substantially does not transmit exposure light, and the semi-transmissive portion includes a portion arranged to be sandwiched by the light shielding portion.
26. The photomask of claim 16,
the transfer pattern has a light-shielding portion formed by patterning a light-shielding film formed on the transparent substrate, and a complementary film having a light-shielding property different from the composition of the light-shielding film is formed near an edge of the modified translucent portion on which the modified film is formed.
27. The photomask of any of claims 16 to 26,
the photomask is used for manufacturing a device for a display device.
28. A method for manufacturing a device for a display device, comprising:
a process of preparing the photomask according to any one of claims 16 to 27; and
and a transfer step of exposing the photomask to light by an exposure device to transfer the transfer pattern to a transfer target.
Technical Field
The present invention relates to a method of correcting defects generated in a photomask, and more particularly, to a method of correcting (repair) a photomask suitable for use in manufacturing a display device, a photomask subjected to correction, a method of manufacturing a photomask, and a method of manufacturing a device for a display device using a photomask.
Background
As a photomask used in a semiconductor integrated circuit, an attenuation-type (or halftone-type) phase shift mask is known. The phase shift mask is formed by forming a portion corresponding to a light shielding portion of a Binary mask with a halftone film (halftone film) having a low transmittance and a phase shift amount of 180 degrees.
Patent document 1 describes the following: that is, when a defect occurs in the phase shift portion having such a phase shift mask, a correction member having substantially the same transmittance and substantially the same phase shift amount as those of the phase shift portion is disposed in the phase shift defective portion.
On the other hand, it is known that, in manufacturing a liquid crystal display device, a multi-tone mask (multi-tone mask) is used in order to improve the production efficiency. Patent document 2 describes the following method: that is, there is a multi-tone photomask having a semi-transparent portion in which a semi-transparent film is formed on a transparent substrate, in addition to a light-shielding portion and a transparent portion, and a correction film is formed on a defect generated in the semi-transparent portion to correct the defect. Thus, the phase difference between the light-transmitting portion exposed from the transparent substrate and the correction portion having the correction film formed on the transparent substrate is 80 degrees or less. Thus, defects such as short-circuiting of the channel of the thin film transistor due to a decrease in transmittance due to retardation can be suppressed at the boundary between the adjacent light-transmitting portion and the correcting portion.
Further, patent document 3 proposes a photomask using a phase shift film having a high transmittance (30% or more) in the production of a display device.
Disclosure of Invention
Problems to be solved by the invention
For example, when a defect occurs in a pattern portion formed of a halftone film which the halftone type phase shift mask has, it is not necessarily easy to correct the defect. In general, it is known that when a defect is generated in a photomask and the defect is to be corrected by a correction film, a FIB (focused ion beam) apparatus is used as a correction means.
The FIB device mainly uses gallium ions to deposit a carbon-based film, but the inventors have studied that, in a method of simply depositing a correction film on a defective portion of a photomask using the FIB device, the same function as that of a photomask in which no defect is generated may not be recovered. If the photomask to be corrected is a so-called binary mask, the correction operation is relatively easy. On the other hand, the study by the present inventors revealed that, when the correction target is a halftone-type phase shift mask, even if the FIB device is used, the amount of phase shift with respect to the exposure light is about 180 degrees when the correction film is deposited on the defective portion of the photomask, and it is not easy to form a correction film having a desired transmittance set for a halftone film in a normal portion. This also relates to a case where the FIB device is designed for correction of the light shielding film and adjustment of the phase shift amount and the transmittance to desired values individually is not assumed. That is, there are problems as follows: in order to investigate the possibility of applying the FIB device to the correction of the phase shift mask, it is necessary to search for a material and a forming condition of the correction film, and even then, it is not always possible to realize optical performance such as different transmittance depending on the phase shift mask, depending on the results of the above efforts.
Although the defect correction by the FIB device is advantageous for deposition of a correction film for a minute defect, the laser CVD method described later is more advantageous in terms of efficiency of rapidly and uniformly covering a region to be corrected with the correction film. Therefore, in general, the laser CVD method is more advantageous than the FIB apparatus in the correction of a photomask for manufacturing a large-sized display device (hereinafter referred to as "FPD").
In the above-mentioned patent document 2, a laser CVD method is used for defect correction of a semi-transparent film forming a semi-transparent portion. In this way, the correction film can be deposited relatively efficiently on the defective portion, and the method can be applied more easily to a large-sized photomask for an FPD. However, the correction film formed in this manner is a correction film for a semi-transparent film having no phase shift effect.
Currently, in a display device, a trend toward high definition is remarkable along with an increase in pixel density. In addition, the portable terminal is required to have particularly high brightness and low power consumption. In order to realize this, a photomask used in a manufacturing process also includes minute portions, and a technique for reliably resolving these minute portions is required. The tendency of resolution improvement is not necessarily limited to the exposure apparatus, and a technique for improving resolution is expected for a photomask. Thus, patent document 3 proposes a transfer pattern using a phase shift effect also in a mask for an FPD.
However, it is significantly difficult to obtain a correction film having the same transmittance and phase shift amount as a semi-transparent film (hereinafter, also referred to as a "normal semi-transparent film") that is initially formed in a photomask manufacturing process, against defects generated in the semi-transparent film having a phase shift effect. In particular, no method for forming a correction film for a semi-transmissive portion having a high transmittance (for example, 25% or more) and a phase shift effect has been established.
The main object of the present invention is to provide a technique capable of performing precise correction even when a defect occurs in a photomask utilizing a phase shift effect.
Means for solving the problems
(aspect 1)
A photomask correction method according to claim 1 of the present invention is a photomask correction method for correcting a defect generated in a photomask having a transfer pattern including a semi-transparent portion formed by patterning a semi-transparent film on a transparent substrate, the photomask correction method including the steps of: a step of determining the defect to be corrected; and a correction film forming step of forming a correction film for correcting the defect, wherein the semi-transmissive section has a transmittance Tm (%) for light having a representative wavelength of exposure light and a phase shift amount Φ m (degree), 160 ≦ Φ m ≦ 200, and in the correction film forming step, a 1 st film and a 2 nd film having different compositions are laminated in an arbitrary order, the 1 st film containing Cr and O, the 2 nd film containing Cr, O and C, the 1 st film containing no C or C in a content smaller than the 2 nd film, and the 2 nd film containing O in a content smaller than the 1 st film.
(aspect 2)
The aspect 2 of the invention is characterized in that,
according to the photomask correction method described in the above aspect 1, Tm > 25.
(aspect 3)
The aspect 3 of the invention is characterized in that,
according to the photomask correction method of the above-described aspect 1 or 2,
the correction film has a transmittance Tr (%) and a phase shift amount phi r (degree) for light of the representative wavelength satisfying 30 < Tr < 75 and 160 < phi r < 200.
(aspect 4)
The invention of the 4 th aspect is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 3,
in the correction film formation step, a laser CVD method is applied.
(aspect 5)
The aspect 5 of the invention is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 4, wherein the transmittance T1 (%) and the amount of phase shift Φ 1 (degrees) of the 1 st film with respect to the light of the representative wavelength and the transmittance T2 (%) and the amount of phase shift Φ 2 (degrees) of the 2 nd film with respect to the light of the representative wavelength satisfy the following relationships (1) to (4), respectively:
(1)100≤φ1＜200
(2)φ2＜100
(3)55≤T1
(4)25＜T2＜80。
(aspect 6)
The feature of the 6 th aspect of the present invention is that,
the method for correcting a photomask according to any one of the above aspects 1 to 5, wherein the content of Cr contained in the 2 nd film is larger than the content of Cr contained in the 1 st film.
(aspect 7)
The invention of claim 7 is characterized in that,
the method for correcting a photomask according to any one of the above aspects 1 to 6, wherein a total content of Cr and O contained in the 1 st film is 80% or more of a composition of the 1 st film in terms of atomic%.
(aspect 8)
The aspect 8 of the invention is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 7,
the 1 st film is composed of a material containing 5 to 45 atomic% of Cr and 55 to 95 atomic% of O,
the 2 nd film is composed of a material containing 20 to 70 atomic% of Cr, 5 to 45 atomic% of O, and 10 to 60 atomic% of C.
(aspect 9)
The invention of the 9 th aspect is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 8, the 2 nd film is laminated on the 1 st film.
(aspect 10)
The 10 th aspect of the present invention is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 9,
the transfer pattern includes a light shielding portion that does not substantially transmit exposure light.
(the 11 th aspect)
The invention of the 11 th aspect is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 10,
the transfer pattern includes a light shielding portion that does not substantially transmit exposure light, and the semi-transmissive portion is disposed so as to be sandwiched by the light shielding portion.
(aspect 12)
The invention of the 12 th aspect is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 11,
the correction film forming step is followed by a post-stage step of forming a supplementary film having a light-shielding property to modify the shape of the correction translucent portion on which the correction film is formed.
(aspect 13)
The invention of the 13 th aspect is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 12,
the method further includes a pretreatment step of removing a film at or around the defect to expose the transparent substrate, prior to the correction film forming step.
(aspect 14)
The aspect 14 of the invention is characterized in that,
the photomask correction method according to any one of the above aspects 1 to 13,
the photomask is used for manufacturing a device for a display device.
(aspect 15)
The method for manufacturing a photomask according to claim 15 of the present invention is characterized by including the method for correcting a photomask according to any one of the above aspects 1 to 14.
(aspect 16)
The photomask according to claim 16 of the present invention is a photomask having a transfer pattern including a semi-transmissive portion formed by patterning a semi-transmissive film formed on a transparent substrate, the photomask having a correction film formed on a defective portion generated in the semi-transmissive portion,
the semi-light-transmitting section has a transmittance Tm (%) and a phase shift amount φ m (degrees) for light of a representative wavelength of exposure light, wherein Tm > 25, 160 ≦ φ m ≦ 200,
the correction film has a laminated film obtained by laminating a 1 st film containing Cr and O and a 2 nd film containing Cr, C and O in an arbitrary order,
the 1 st film contains no C, or contains C in an amount less than that of the 2 nd film,
the 2 nd film contains O in an amount less than that of the 1 st film.
(aspect 17)
The 17 th aspect of the present invention is characterized in that,
according to the photomask of the aspect 16,
the correction film has a transmittance Tr (%) and a phase shift amount phi r (degree) for light of the representative wavelength satisfying 30 < Tr < 75 and 160 < phi r < 200.
(aspect 18)
The 18 th aspect of the present invention is characterized in that,
according to the photomask of the 16 th or 17 th aspect,
the correction film is a laser CVD film.
(aspect 19)
The 19 th aspect of the present invention is characterized in that,
the photomask according to any of aspects 16 to 18,
the transmittance T1 (%) and the amount of phase shift Φ 1 (degrees) of the 1 st film with respect to the light of the representative wavelength, and the transmittance T2 (%) and the amount of phase shift Φ 2 (degrees) of the 2 nd film with respect to the light of the representative wavelength satisfy the following relationships (1) to (4), respectively:
(1)100≤φ1＜200
(2)φ2＜100
(3)55≤T1
(4)25＜T2＜80。
(aspect 20)
The aspect 20 of the invention is characterized in that,
the photomask according to any of aspects 16 to 19,
the 1 st film and the 2 nd film each contain Cr, and the content of Cr contained in the 2 nd film is larger than the content of Cr contained in the 1 st film.
(aspect 21)
The aspect 21 of the invention is characterized in that,
according to the photomask of the above-mentioned aspect 20,
the total content of Cr and O contained in the 1 st film is 80% or more of the composition of the 1 st film in terms of atomic%.
(aspect 22)
The 22 nd aspect of the present invention is characterized in that,
the photomask according to any one of the above aspects 16 to 21,
the 1 st film is composed of a material containing 5 to 45 atomic% of Cr and 55 to 95 atomic% of O,
the 2 nd film is composed of a material containing 20 to 70 atomic% of Cr, 5 to 45 atomic% of O, and 10 to 60 atomic% of C.
(aspect 23)
The aspect 23 of the invention is characterized in that,
the photomask according to any one of the above aspects 16 to 22,
the 2 nd film is laminated on the 1 st film.
(aspect 24)
The aspect 24 of the present invention is characterized in that,
the photomask according to any one of the above aspects 16 to 23,
the transfer pattern has a light-shielding portion formed by patterning a light-shielding film formed on the transparent substrate.
(aspect 25)
The 25 th aspect of the present invention is characterized in that,
the photomask according to any one of the above aspects 16 to 23,
the transfer pattern includes a light shielding portion that substantially does not transmit exposure light, and the semi-transmissive portion includes a portion arranged to be sandwiched by the light shielding portion.
(aspect 26)
The 26 th aspect of the present invention is characterized in that,
the photomask according to any one of the above aspects 16 to 23,
the transfer pattern has a light-shielding portion formed by patterning a light-shielding film formed on the transparent substrate, and a complementary film having a light-shielding property different from the composition of the light-shielding film is formed near an edge of the modified translucent portion on which the modified film is formed.
(aspect 27)
The invention of claim 27 is characterized in that,
the photomask according to any one of the above aspects 16 to 26,
the photomask is used for manufacturing a device for a display device.
(aspect 28)
The method for manufacturing a device for a display device according to the 28 th aspect of the present invention is characterized in that,
the manufacturing method of the device for the display device comprises the following steps:
a step of preparing the photomask according to any one of aspects 16 to 27; and
and a transfer step of exposing the photomask to light by an exposure device to transfer the transfer pattern to a transfer target.
Effects of the invention
According to the present invention, even if a defect occurs in a photomask using a phase shift effect, precise correction can be performed.
Drawings
Fig. 1 is an explanatory view schematically showing an outline of a photomask correction method in embodiment 1 of the present invention, (a) is a view showing an example of a normal pattern, (b) is a view showing an example of a white defect, (c) is a view showing an example of film formation of the 1 st film, and (d) is a view showing an example of film formation of the 2 nd film.
Fig. 2 is an explanatory view schematically showing an outline of a photomask correction method in embodiment 2 of the present invention, (a) is a view showing an example of a normal pattern, (b) is a view showing an example of a white defect, (c) is a view showing an example of film removal in the periphery of a defect, (d) is a view showing an example of the 1 st film formation, (e) is a view showing an example of the 2 nd film formation, and (f) is a view showing an example of the light-shielding complementary film formation.
Fig. 3 is an explanatory view schematically showing an outline of the photomask correction method in embodiment 3 of the present invention, (a) is a view showing an example of a normal pattern, (b) is a view showing an example of a white defect, (c) is a view showing an example of film removal in the periphery of a defect, (d) is a view showing an example of the 1 st film formation, (e) is a view showing an example of the 2 nd film formation, and (f) is a view showing an example of the light-shielding complementary film formation.
Fig. 4 is an explanatory view illustrating optical characteristics of a correction film formed by the photomask correction method of the present invention, (a) is a view showing a specific example of a relationship between a phase shift amount and a transmittance in the case where a 1 st film as a phase shift control film is a single layer, (b) is a view showing a specific example of a relationship between a phase difference and a transmittance in the case where a 2 nd film as a transmission control film is a single layer, and (c) is a view showing a specific example of a relationship between a phase shift amount and a transmittance of a correction film (laminated film) obtained by laminating the 1 st film and the 2 nd film.
Description of reference numerals:
1 … transparent substrate
2 … semi-transparent film
3 … light-shielding film
4 … correction film
4a … film No. 1
4b … film No. 2
5 … supplemental film
10, 10' … transfer pattern
11 … light-transmitting part
12 … semi-transparent part
12a … modified translucent part
13 … light-shielding part
20 … white defect
21, 22 … correction area
Detailed Description
Embodiments of a photomask correction method, a photomask manufacturing method, a photomask, and a method for manufacturing a device for a display device according to the present invention will be described below.
The photomask correction method according to the present invention can be applied when a defect occurs in the transfer pattern formed on the transparent substrate.
< photomask as an object of defect correction >
Here, a photomask to which the photomask correction method of the present invention is applied will be described.
A photomask to which the photomask correction method of the present invention is applied has a transfer pattern formed on a transparent substrate by patterning one or a plurality of optical films, respectively. At least one of the optical films is a semi-transparent film having a predetermined transmittance and a predetermined phase shift action with respect to the exposure light. The semi-transmissive film is a film that shifts the phase of the transmitted exposure light by a desired amount.
That is, the photomask correction method of the present invention may be applied to a photomask or a photomask intermediate in which a photomask blank (or a photomask intermediate) having at least the semi-transparent film formed on a transparent substrate is prepared and a pattern for transfer is formed by a photolithography step.
The transfer pattern includes, for example, a transfer pattern including a translucent portion and a translucent portion formed by patterning a translucent film formed on a transparent substrate, or a transfer pattern including a translucent portion, a light-shielding portion, and a translucent portion formed by patterning a translucent film and a light-shielding film formed on a transparent substrate, respectively.
The present invention can be advantageously applied when the photomask is a photomask for an FPD.
Unlike a photomask for manufacturing a semiconductor device, a photomask for an FPD generally has a large size (for example, one side of a main surface is a quadrangle of about 200 to 2000mm, and a thickness is about 5 to 20 mm), and has a weight, and its size is various.
The transparent substrate is not particularly limited as long as it has sufficient transparency to the exposure wavelength used for exposure of the photomask. For example, quartz or various other glass substrates (soda-lime glass, aluminosilicate glass, and the like) can be used, but a quartz substrate is particularly preferable.
The optical characteristics of the semi-light-transmitting film constituting the semi-light-transmitting portion are as follows.
The object of the photomask correction method of the present invention is a semi-transmissive section having a transmittance Tm (%) for light of a representative wavelength of exposure light. The effect of the invention is particularly remarkable when Tm is 25 < Tm. For example, 25 < Tm ≦ 80.
In the specification of the present application, the transmittance is a transmittance when the transmittance of the transparent substrate is 100%.
The exposure light mainly has a wavelength of 300-500 nm and can be used as a light source of an exposure device of the FPD photomask. For example, it is preferable to use a light source having a wavelength range including any one or more of i-line, h-line, and g-line, and particularly, a high-pressure mercury lamp including these wavelengths is widely used.
In this case, the representative wavelength of the exposure light may be any wavelength included in the wavelength range of i-line to g-line. For example, the representative wavelength can be defined as an h-line (405nm) near the center of the wavelength ranges. In the following description, unless otherwise specified, the h-line is described as a representative wavelength. Of course, a wavelength region on the shorter wavelength side than the above wavelength (for example, 300 to 365nm) may be used as the exposure light.
Further, the phase shift amount Φ m of the semi-light transmissive film may be set to be about 180 degrees with respect to the light of the representative wavelength. Here, about 180 degrees means a range of 160 to 200 degrees. More preferably, the phase shift amount is 160 to 200 degrees for all the main wavelengths (e.g., i-line, h-line, g-line) included in the exposure light.
Preferably, the deviation of the phase shift amount in the wavelength region from i line to g line is 40 degrees or less.
In addition, the photomask including the semi-transmissive portion having the transmittance Tm and the phase shift Φ m can improve the resolution of the transfer pattern compared to a so-called binary mask. For example, photomasks are known as follows: that is, the translucent portion is disposed adjacent to the semi-translucent portion, and the resolution is improved by diffraction and interference caused by each transmitted light generated at the boundary. In such a so-called phase shift mask, it is a mainstream to set the transmittance of the semi-transmissive portion to 10% or less.
On the other hand, the transfer pattern may have a light shielding portion in addition to the light transmitting portion and the semi-light transmitting portion. That is, a photomask having a transfer pattern formed by patterning a semi-light-transmitting film and a light-shielding film formed on a transparent substrate may be the target of the photomask correction method of the present invention.
For example, as in the photomask described in patent document 3, when the light transmitting portion and the semi-light transmitting portion are not adjacent to each other and the light shielding portion is disposed between the light transmitting portion and the semi-light transmitting portion, and when the semi-light transmitting portion is further sandwiched by the intervening light shielding portion, the following advantages can be obtained by using light which has transmitted through the semi-light transmitting portion and is in a phase in an inverse relationship with the light transmitting portion: that is, the focus depth is increased (increased), and then the MEEF (mask error increase coefficient), Dose amount of light energy required for exposure, and the like are decreased.
Thus, a transfer pattern may be designed as follows: that is, the semi-transmissive portion having a phase shift effect is not directly adjacent to the transmissive portion, but is disposed at a predetermined position in the vicinity via the light shielding portion or the semi-transmissive portion having substantially no phase shift effect. In this case, it is useful to design the transmittance Tm of the translucent portion having a phase shift effect to be relatively high (for example, Tm > 25) with respect to the transmittance (for example, 10% or less) of a general halftone type phase shift mask, and a significant effect is exerted on the improvement of resolution performance. With respect to such a phase-shifted semi-transmissive portion having a high transmittance, a more preferable range of the transmittance Tm is 30 < Tm ≦ 75, and still more preferably 40 < Tm ≦ 70. In this case, the transmitted light of the translucent portion can be appropriately interfered with the transmitted light of the translucent portion spaced apart from the translucent portion by a predetermined distance, and the light intensity distribution (profile) of the transmitted light formed in the translucent portion can be improved.
Therefore, when defects are generated in the semi-transmissive portion having a high transmittance and a phase shift effect, the defects must be corrected.
In order to correct the related defects, the photomask correction method of the present invention is applied.
< embodiment 1 of the photomask correction method >
Hereinafter, embodiment 1 of the photomask correction method of the present invention will be described with reference to fig. 1.
Fig. 1 (a) shows a normal pattern portion of a photomask to be corrected in embodiment 1. The transfer pattern 10 to be corrected in embodiment 1 includes a transparent portion 11 where the transparent substrate 1 is exposed, and a semi-transparent portion 12 where the semi-transparent film 2 having a phase shift effect is formed on the transparent substrate 1.
First, in the step of identifying the defect, the defect generated in the semi-transmissive film 2 is identified, and the defect is set as a correction target. First, a correction region for forming a correction film 4 described later is determined for a white defect formed by the absence of the semi-transparent film 2, which is originally supposed to be present. If necessary, a step (pretreatment step) of removing an unnecessary film (residual semi-transparent film 2) or foreign matter in the defect portion or the periphery of the defect position may be performed, and after the shape of the correction region where the correction film 4 is formed is trimmed, the correction film 4 may be formed. The removal of the unnecessary residual film 2 may be performed using laser-based transpiration (laser bombardment) or the like.
On the other hand, when the correction of the present invention is performed on the semi-transmissive portion 12 having a residual defect, such as the semi-transmissive portion 12 having a black defect, that is, a foreign substance adhered thereto, or a light-shielding film remaining thereon to be removed by the patterning step, the residual portion may be removed in the same manner as described above, and the correction film 4 of the present invention may be formed in a state where the transparent substrate 1 is exposed.
Fig. 1 (a) shows a transfer pattern 10 formed by patterning a semi-transmissive film 2 having a phase shift effect formed on a transparent substrate 1. The semi-light-transmitting portion 12 has a transmittance Tm (%) for light of a representative wavelength of exposure light (here, line h), Tm > 25. Specifically, as described above, 25 < Tm ≦ 80 may be set, for example. The semi-transmissive section 12 has a phase shift amount Φ m with respect to the light of the representative wavelength. Here,. phi.m.is 160. ltoreq. phi.m.ltoreq.200 (degrees).
Fig. 1 (b) shows a case where a white defect is generated in the semi-transmissive portion 12. The white defect may be a white defect formed by missing the semi-transmissive film 2 which is supposed to be present, or an artificial white defect formed by removing the remainder of the semi-transmissive portion 12 having the remaining defect. As will be described later in detail as a correction film forming step, the correction film 4 is formed on the white defect portion 20 and corrected. The correction film 4 can be formed by a laser CVD method.
The laser CVD method is a method of introducing a film material and applying heat and/or light energy generated by laser irradiation to form a film (also referred to as a laser CVD film). As the film material, Cr (CO) which is an element of metal carbonyl group 6 can be used 6(chromium hexacarbonyl), Mo (CO) 6(molybdenum hexacarbonyl), W (CO) 6(tungsten hexacarbonyl), and the like. Wherein, when Cr (CO) is used 6The film is preferable as a film material for correction of a photomask because it has excellent chemical resistance against cleaning and the like. In embodiment 1, Cr (CO) 6The case of the film material will be described.
As the laser light to be irradiated, a laser light in an ultraviolet region is preferably used. A source gas is introduced into the laser irradiation region, and a film is deposited by the action of photo CVD and/or thermal CVD. For example, an Nd YAG laser having a wavelength of 355nm can be used. As the carrier gas, Ar (argon) may be used, but N (nitrogen) may be contained.
It is assumed that a light-shielding correction film is formed by laser CVD in a general laser CVD apparatus. However, in the present invention, the semi-transparency correction film 4 having a phase shift effect is formed. For this purpose, conditions such as the flow rate and energy power of the introduced gas are selected.
As shown in fig. 1 (d), the correction film 4 of the present invention has a laminated structure of a 1 st film 4a and a 2 nd film 4 b. This stacking order may be any order, and it is not excluded that an additional film is provided within a range not to impair the operational effect of the present invention. In the following description, the 2 nd film 4b is laminated on the 1 st film 4a, whereby the correction film 4 having desired optical properties is formed.
(the 1 st film)
Fig. 1 (c) shows a step of forming the 1 st film 4 a.
In order to make the correction film 4 formed by the lamination of the 1 st film 4a and the 2 nd film 4b laminated thereon have a phase shift amount Φ r (degree) of about 180 degrees with respect to the light of the representative wavelength of the exposure light, the 1 st film 4a is made to have an appropriate phase shift amount Φ 1 (degree). The 1 st film 4a is preferably responsible for 50% or more of the phase shift amount Φ r, that is, functions as a so-called "phase shift control film".
That is, the phase shift amount φ 1 of the 1 st film 4a and the phase shift amount φ r of the correction film 4 can be set to 160 ≦ φ r ≦ 200, and 100 ≦ φ 1 < 200.
The phase shift φ 1 is more preferably 120. ltoreq. φ 1 < 180, and still more preferably 130. ltoreq. φ 1 < 160.
The transmittance T1 of the 1 st film 4a with respect to light of the above-mentioned representative wavelength is preferably 55. ltoreq. T1, more specifically 55. ltoreq. T1. ltoreq.95, more preferably 60. ltoreq. T1. ltoreq.80, and still more preferably 60. ltoreq. T1. ltoreq.70.
In addition, regarding the above-mentioned phase shift amount, for example, 160 ≦ φ r ≦ 200 means a range including 160+360M ≦ φ r ≦ 200+360M (M is a non-negative integer). Hereinafter, the phase shift amount is also defined as the same.
It is preferable that the main components of the 1 st film 4a are Cr (chromium) and O (oxygen). That is, the total of Cr and O is 80% or more of the total composition of the 1 st film 4 a. The total content of Cr and O is more preferably 90% or more, and still more preferably 95% or more.
The content% of the film component represents atomic%. The same applies to the following.
The 1 st film 4a may not contain C (carbon) contained in the raw material gas, but when contained, it is preferably 20% or less, more preferably 10% or less. The C content of the 1 st film 4a is smaller than that of the 2 nd film 4b described later, and is preferably 2/3 or less, more preferably 1/3 or less, of the C content of the 2 nd film 4 b.
It is preferable that the maximum component (having the maximum content) of the 1 st film 4a is O, and the content of O is 50% or more.
The preferable composition of the 1 st film 4a is 5-45% Cr and 55-95% O.
The Cr content of the 1 st film 4a is preferably 5 to 30%.
The 1 st film 4a preferably contains 20 to 30% of Cr and 70 to 80% of O.
The content of Cr in the 1 st film 4a is preferably smaller than that in the 2 nd film 4b described later.
By adopting such a composition as described above, the 1 st film 4a can be a film having high transmittance and having a sufficient amount of phase shift. The 1 st film 4a can be formed by laser CVD.
In order to form the 1 st film 4a with the above composition and achieve the above optical characteristics, the thickness of the 1 st film 4a is set to
Fig. 4 (a) illustrates the optical characteristics of the 1 st film 4 a.
Fig. 4 (a) shows a specific example of the relationship between the amount of phase shift Φ 1 and the transmittance when the vertical axis is the amount of phase shift (degrees), the horizontal axis is the transmittance (%), and the 1 st film 4a as the phase shift control film is a single layer.
(No. 2 film)
Fig. 1 (d) shows a process of forming a 2 nd film 4b on the 1 st film 4 a.
The 2 nd film 4b has a transmittance T2 (%) necessary for adjustment to make the transmittance Tr (%) of the correction film 4 formed by lamination thereof with the 1 st film 4a desired value. That is, the 2 nd film 4b can be a so-called "transmission control film".
The transmittance T1 of the 1 st film 4a and the transmittance T2 of the 2 nd film 4b are preferably T1 > T2.
The 2 nd film 4b preferably has a transmittance T2 of 25 < T2 < 80, more preferably 30. ltoreq. T2 < 70, and still more preferably 45. ltoreq. T2 < 65.
Further, the phase shift amount φ 2 of the 2 nd film 4b is smaller than the phase shift amount φ 1 of the 1 st film 4a, and φ 2 < 100. Specifically, 20. ltoreq. phi.2 < 100, more preferably 20. ltoreq. phi.2 < 60, and still more preferably 30. ltoreq. phi.2 < 50.
The 2 nd film 4b preferably contains Cr, O, and C as main components. That is, Cr, O, and C preferably constitute 90% or more, more preferably 95% or more, of the total components of the 2 nd film 4 b.
Preferably, the 2 nd film 4b contains more C than the 1 st film 4 a.
It is preferable that the content of Cr in the 2 nd film 4b is larger than the content of Cr in the 1 st film 4 a.
Specifically, the composition of the 2 nd film 4b may be 20 to 70% of Cr, 5 to 45% of O, and 10 to 60% of C.
More preferably, the composition of the 2 nd film 4b may be 40 to 50% of Cr, 15 to 25% of O, and 25 to 35% of C.
In the case of forming the 1 st film 4a and the 2 nd film 4b by the laser CVD method, the raw material gases having different components or component ratios may be used, or different compositions and physical properties may be obtained by using the same raw material gas and simultaneously using different forming conditions.
In embodiment 1, the source gases for the 1 st film 4a and the 2 nd film 4b are the same (cr (co)6), but different forming conditions are applied.
That is, the flow rate of the source gas is set to be smaller than that of the 2 nd film 4b (for example, 1/2 or less, and further, 1/8 to 1/6 or the like) in forming the 1 st film 4a, and the irradiation power density of the laser light may be set to be smaller than that of the 2 nd film 4b (for example, 1/2 or less). These are effective methods for limiting the decomposition reaction of the source gas and forming the 1 st film 4a having a sufficient amount of phase shift without excessively decreasing the transmittance.
For example, the flow rate of the raw material gas may be 30 cc/min or less, preferably 10 to 20cc/min, and the laser irradiation power density was 3mW/cm 2Preferably 1 to 2mW/cm 2. The laser irradiation time may be 10 seconds or more, preferably 20 to 30 seconds. That is, the flow rate of the source gas and the laser irradiation power density for forming the 1 st film 4a are set to be relatively low and energy is relatively low, and it is useful to apply film formation for a long time as compared with the 2 nd film 4b described later.
On the other hand, when the 2 nd film 4b is formed, the flow rate of the source gas is increased and the content of C is increased as compared with the case of the 1 st film 4 a. Preferably, the laser irradiation power density for forming the 2 nd film 4b is also larger than that for the 1 st film 4 a. Thus, even if the decomposition reaction of the source gas is promoted and the film thickness is reduced, the 2 nd film 4b having a transmittance smaller than that of the 1 st film 4a is formed.
For example, the flow rate of the source gas for forming the 2 nd film 4b is 60 cc/min or more, preferably about 80 to 110 cc/min, and the laser irradiation power density is set to 6mW/cm 2Above, preferably 8-12 mW/cm 2. The laser irradiation time may be shorter than that of the 1 st film 4a, and is, for example, 1.0 second or less, preferably 0.5 to 0.8 seconds. That is, as the flow rate of the source gas and the laser irradiation power density for forming the 2 nd film 4b, conditions of a relatively high flow rate, a relatively high energy, and a short time can be adopted.
The formation condition of the 2 nd film 4b may be referred to as a so-called high energy condition larger than that applied to formation of a correction film having light-shielding properties (for example, correction of a binary mask) by laser CVD.
By applying such conditions, the 2 nd film 4b becomes a thin film, and the phase shift amount Φ 2 is extremely small, and further, since the film density is high, the film is also excellent in chemical resistance.
With the above composition, the film thickness of the 2 nd film 4b can be set to a film thickness that complements the desired optical characteristics
Fig. 4 (b) illustrates the optical characteristics of the 2 nd film 4 b.
Fig. 4 (b) shows a specific example of the relationship between the amount of phase shift Φ 2 and the transmittance T2 when the vertical axis is expressed as the amount of phase shift (degrees) and the horizontal axis is expressed as the transmittance (%) and the 2 nd film 4b as the transmission control film is a single layer.
(laminated film)
By laminating the 1 st film 4a and the 2 nd film 4b, the correction film 4 having the following phase shift amount Φ r (degree) and transmittance Tr (%) with respect to the light of the representative wavelength can be formed. That is, the correction film 4 obtained by laminating the 1 st film 4a and the 2 nd film 4b may be formed as the correction film 4
160≤φr≤200
Tr＞25。
The transmittance Tr of the correction film 4 may preferably be in the same range as the transmittance Tm of the semi-transmissive portion, i.e., 30 < Tr.ltoreq.75, and more preferably 40 < Tr.ltoreq.70.
The order of lamination of the 1 st film 4a and the 2 nd film 4b may be arbitrary. However, the 2 nd film 4b has higher chemical resistance than the 1 st film 4a due to the difference in the above-described composition, and therefore, the 2 nd film 4b is preferably arranged on the upper layer side because the cleaning resistance and the like can be improved.
As the correction film 4 including the 1 st film 4a and the 2 nd film 4b, the Cr — C — O composition ratio may be set to Cr: 30-70%, O: 5-35%, C: 20 to 60, more preferably Cr: 40-50%, O: 5-25%, C: 35-45%.
Fig. 4 (c) shows an example of the optical characteristics of the correction film 4 obtained by laminating the 1 st film 4a and the 2 nd film 4 b.
Fig. 4 (c) shows a specific example of the relationship between the amount of phase shift and the transmittance of the correction film 4 obtained by laminating the 1 st film 4a and the 2 nd film 4b with the vertical axis as the amount of phase shift (degrees) and the horizontal axis as the transmittance (%). As is apparent from fig. 4, the correction film 4 obtained by laminating the 1 st film 4a and the 2 nd film 4b has optical characteristics having a phase shift effect and a high transmittance with respect to the exposure light, which are a relationship between the amount of phase shift and the transmittance that cannot be obtained in any of the case where the 1 st film 4a is a single layer (see fig. 4 a) and the case where the 2 nd film 4b is a single layer (see fig. 4 b).
That is, by applying the photomask correction method according to the above-described procedure, even if a defect occurs in the semi-transmissive film 2 having a predetermined transmittance and a phase shift effect, precise correction for recovering the optical characteristics can be performed. More specifically, according to the photomask correction method of embodiment 1, the correction film 4 has a 2-layer structure, and thus, it is possible to perform correction so as to have optical properties that are almost the same as those of a phase shift film having a high transmittance, which is difficult to achieve. Here, since the 1 st film 4a and the 2 nd film 4b can be formed by the same film forming method (here, laser CVD method), it is not necessary to use a plurality of types of correction devices. This is very advantageous in, for example, correction of a photomask for manufacturing a display device, which will be described later.
In embodiment 1 shown in fig. 1, the semi-transmissive portion 12 is adjacent to the transmissive portion 11. In such a transfer pattern, after the correction film 4 having a required area or more is formed by the above-described steps, the vicinity of the outer edge of the correction film 4 is removed, and the edge shape of the correction film 4 at the boundary with the light-transmitting portion 11 can be trimmed. Means therefor may be, for example, Laser bombardment (Laser Zap). Thus, even when the side surface is inclined during the formation of the correction film 4, the edge shape of the film closer to the side surface perpendicular to the transparent substrate 1 or the like can be modified, and the phase shift effect generated at the boundary portion can be more favorably exhibited.
< embodiment 2 of the photomask correction method
Next, embodiment 2 of the photomask correction method of the present invention will be described with reference to fig. 2.
Fig. 2 shows a correction method for a case where a defect occurs in a photomask having a transfer pattern 10' formed by patterning a translucent film 2 and a light-shielding film 3 on a transparent substrate 1.
That is, the transfer pattern 10' to be corrected in embodiment 2 includes a transparent portion where the transparent substrate 1 is exposed, a light shielding portion 13 where at least the light shielding film 3 is formed on the transparent substrate 1, and a semi-transparent portion 12 where the semi-transparent film 2 having a phase shift effect is formed on the transparent substrate 1. Fig. 2 (a) shows only the light-shielding portion 13 and the translucent portion 12, and illustration of the translucent portion is omitted. An antireflection layer may be formed on the surface layer of the light-shielding film 3.
In embodiment 2, the semi-transmissive portion 12 and the light-shielding portion 13 are disposed adjacent to each other, and sandwiched in the direction in which the semi-transmissive portion 12 and the light-shielding portion 13 are arranged. In fig. 2 (a), the semi-transmissive portion 12 is not adjacent to the transmissive portion.
Here, the semi-transmissive section 12 is composed of a phase shift film having the same transmittance Tm (%) and phase shift amount Φ m (degree) as in the case of embodiment 1. The light shielding portion 13 is a film that does not substantially transmit exposure light, and preferably has an OD (optical Density) of not less than 3.
Fig. 2 (b) shows a case where the white defect 20 is generated in the semi-transmissive portion 12 of the photomask shown in fig. 2 (a).
Fig. 2 c shows a step (preprocessing step) of removing the semi-light-transmitting film 2 and the light-shielding film 3 located in the periphery of the white defect 20 to expose the transparent substrate 1, and modifying the shape of a region (hereinafter, also referred to as a correction region) 21 for forming the correction film 4. The film removal method may employ Laser-based transpiration (Laser Zap) or the like.
Fig. 2 (d) shows a step of forming a 1 st film 4a on the exposed surface of the transparent substrate 1 in the correction region 21, similarly to the case of embodiment 1. Fig. 2 (e) shows a 2 nd film 4b laminated on the 1 st film 4a thus formed.
The optical properties, composition and film forming conditions of the 1 st film 4a and the 2 nd film 4b may be the same as those of embodiment 1. Therefore, the formed correction film 4 having a two-layer structure is also the same as that of embodiment 1.
In embodiment 2, the correction region 21 is adjacent to the light-shielding portion 13 or the translucent portion 12. Further, here, an example is shown in which the correction region 21 is surrounded by the light shielding portion 13 and/or the semi-transmissive portion 12. Here, the correction film is formed so that the edge of the semi-light-transmitting film 2 and/or the light-shielding film 3 forming the outer edge of the correction region 21 and the edge of the 1 st film 4a or the 2 nd film 4b do not overlap with each other. This is because if the 1 st film 4a and/or the 2 nd film 4b overlaps the edge of the remaining semi-transmissive film 2, the transmittance of the overlapping portion is lower than that of the normal semi-transmissive film 2, and a failure occurs in which the pattern is not transferred as designed.
Further, it is considered that when the 1 st film 4a and/or the 2 nd film 4b overlap with the edge of the remaining light shielding portion 13, energy is applied to a component (for example, Cr) of the light shielding film 3 at the edge portion of the light shielding film 3, thereby starting unnecessary film growth, and causing a change in transmittance of the semi-light transmitting portion (including the one after correction) 12 in the vicinity.
Therefore, it is preferable to perform a correction step of adjusting the edge position so that the edge of the 1 st film 4a and/or the 2 nd film 4b does not overlap with the edges of the semi-light-transmitting film 2 and the light-shielding film 3 remaining on the transparent substrate 1. Alternatively, as shown in fig. 2 (c) and (d), it is preferable to apply a correction step in which the edge of the 1 st film 4a and/or the 2 nd film 4b is slightly separated from the edge of the semi-light-transmitting film 2 and the light-shielding film 3 remaining on the transparent substrate 1.
The separation distance between the edge of the 1 st film 4a and/or the 2 nd film 4b and the edges of the semi-light-transmitting film 2 and the light-shielding film 3 is preferably 1 μm or less. For example, the separation distance may be set to 0.1 μm to 1 μm. Since the separation distance is smaller than the resolution limit of an exposure apparatus that exposes the photomask, the transfer of the separator to the transfer object does not substantially occur.
In embodiment 2, in the preprocessing step in fig. 2 c, since the light shielding portion 13 is subjected to film removal, the shape of the modified semi-transmissive portion (the semi-transmissive portion in which the modified film is formed partially or entirely in the semi-transmissive portion is also referred to as a modified semi-transmissive portion) 12a is different from the shape of the normal pattern at the time of fig. 2 e when the formation of the modified film 4 is completed. Specifically, the width (CD) of the modified translucent portion 12a is larger than the width (CD) of the translucent portion 12 in the normal pattern.
Thus, in fig. 2 (f), a post-process for forming the CD into a designed CD is performed.
That is, in fig. 2 (f), the light-shielding supplementary film 5 is formed around the edge so that the modified translucent portion 12a becomes the correct CD. As a method for forming the supplementary film 5, for example, a focused ion beam method (focused ion beam deposition) may be used, or a laser CVD method may also be used.
The method of forming the replenishment film 5 may be different from that of forming the light-shielding film 3 in a normal pattern, and thus the composition or composition ratio is different, that is, different from the composition of the light-shielding film 3. The supplementary film 5 is, for example, a film containing carbon as a main component.
Preferably, the Optical compensation film 5 does not substantially transmit the exposure light and has an OD (Optical Density) of 3 or more.
In fig. 2 (f), the supplementary film 5 is formed so that the CD of the corrected semi-transmissive portion 12a is the same as the normal semi-transmissive portion 12 before correction. However, when the transmittance of the modified translucent portion 12a is excessive or insufficient with respect to the target value, the CD of the modified translucent portion 12a can be made larger than the normal translucent portion 12 or smaller than the normal translucent portion 12 for the purpose of fine adjustment to approach the target value.
That is, after the completion of the formation step of the correction film 4 and before the subsequent step, the optical performance of the correction film 4 is checked, and in addition to this result, the size of the formation of the complementary film 5 performed in the subsequent step may be increased or decreased. In this case, the formed modified translucent portion 12a has a locally smaller CD or a locally larger CD than the normal translucent portion 12.
By applying the photomask correction method according to the above-described procedure, it is possible to precisely correct defects generated in the semi-transmissive film 2 having a predetermined transmittance and a phase shift function, as in the case of embodiment 1.
< embodiment 3 of the photomask correction method >
Next, embodiment 3 of the photomask correction method of the present invention will be described with reference to fig. 3.
Fig. 3 further illustrates another correction method in the case where a defect occurs in a photomask having a transfer pattern 10' formed by patterning the translucent film 2 and the light-shielding film 3 on the transparent substrate 1.
The transfer pattern 10' to be corrected in embodiment 3 includes a transparent portion where the transparent substrate 1 is exposed, a light shielding portion 13 where at least the light shielding film 3 is formed on the transparent substrate 1, and a semi-transparent portion 12 where the semi-transparent film 2 having a phase shift effect is formed on the transparent substrate 1. Fig. 3 (a) shows only the light-shielding portion 13 and the translucent portion 12, and illustration of the translucent portion is omitted. An antireflection layer may be formed on the surface layer of the light-shielding film 3.
In embodiment 3, the semi-transmissive portion 12 is adjacent to the light-shielding portion 13, but is not adjacent to the light-transmissive portion.
Here, the semi-transmissive section 12 is composed of a phase shift film having the same transmittance Tm (%) and phase shift amount Φ m (degree) as in the case of embodiment 1 described above. The light shielding portion 13 is a film that substantially does not transmit exposure light, and preferably has an OD of not less than 3.
Fig. 3 (b) shows a case where the white defect 20 is generated in the semi-transmissive portion 12 of the photomask shown in fig. 3 (a).
Fig. 3 (c) shows a pretreatment step of removing all the translucent film 2 in the region continuous with the translucent portion 12 where the white defect 20 is generated, exposing the transparent substrate 1, and trimming the shape of the correction region 22. Here, the semi-transmissive film 2 is removed and a part of the adjacent light-shielding film 3 is also removed. The means for film removal may be Laser-based transpiration (Laser Zap) or the like.
Fig. 3 (d) shows a step of forming a 1 st film 4a as a phase adjustment film on the exposed surface of the transparent substrate 1 in the correction region 22, similarly to the case of embodiment 1. Further, fig. 3 (e) shows that a 2 nd film 4b is laminated as a transmission adjusting film on the 1 st film 4a formed.
The optical properties, composition and film forming conditions of the 1 st film 4a and the 2 nd film 4b may be the same as those of embodiment 1. Therefore, the formed correction film 4 having a two-layer structure is also the same as that of embodiment 1.
In embodiment 3, since all the semi-transmissive film 2 continuous with the defect-generated semi-transmissive film is removed, the correction film is not adjacent to the normal semi-transmissive film in the photomask after the correction. Therefore, the separation or the overlapping of the two films in the boundary of the correction film and the normal semi-transparent film does not occur. When the size becomes large, there is a risk of being transferred onto the transferred body in a separated or overlapped state, but in the present embodiment 3, there is no such risk, which is advantageous.
In embodiment 3, since the film removal related to the light shielding portion 13 is performed in the preprocessing step in fig. 3 (c), the size of the correction semi-transparent portion 12a is different from the size of the normal pattern at the time of fig. 3 (e) when the formation of the correction film 4 is completed. Specifically, the width (CD) of the modified translucent portion 12a is larger than the width (CD) of the translucent portion 12 in the normal pattern.
Thus, in fig. 3 (f), a post-stage process for making the CD as designed is performed. This point is the same as in embodiment 2.
The composition and optical characteristics of the light-shielding supplementary film 5 formed in the subsequent step may be the same as those of embodiment 2. Note that the transmittance of the correction semi-transmissive portion 12a may be adjusted by the formation size of the supplemental film 5 as necessary, as in embodiment 2.
By applying the photomask correction method according to the above-described procedure, defects generated in the semi-transmissive film 2 having a predetermined transmittance and a phase shift function can be precisely corrected, as in the case of embodiment 1.
< method for manufacturing photomask >
The present invention also includes a method for manufacturing a photomask including the photomask correction method described above.
The method for manufacturing a photomask of the present invention can be performed by the following steps.
First, a photomask blank including a translucent film having a phase shift effect and a necessary optical film formed on a transparent substrate is prepared. The photomask blank referred to herein includes a photomask blank that has been provided with a part of the film pattern. Then, a resist pattern is formed by drawing a desired pattern on a resist film (positive type or negative type) formed on the photomask blank by a laser drawing apparatus or the like and developing the pattern. Then, the optical film is etched using the resist pattern as a mask, thereby forming a transfer pattern. Any of dry etching and wet etching can be used for etching, but wet etching is advantageous for display devices, and therefore wet etching is widely used.
The photomask having the transfer pattern formed thereon (or a photomask intermediate on which film formation or pattern formation is further performed) is inspected for defects. When a white defect or a black defect is found, the photomask is corrected by applying the above-described photomask correction method of the present invention.
Through the above process, even if a defect occurs in the transfer pattern using the phase shift effect, the photomask can be manufactured while performing precise correction.
< photomask >
The present invention also includes a photomask to which the above-described photomask correction method is applied.
The photomask has a transfer pattern including a translucent portion formed by patterning a translucent film formed on a transparent substrate. The photomask further includes a modified translucent portion in which a modified film including a material different from that of the translucent film is partially formed. The photomask is obtained by forming a correction film for defects generated in the semi-transmissive portion.
The semi-light transmitting part of the photomask has a transmittance Tm (%) for light of a representative wavelength of exposure light (wherein Tm > 25) and a phase shift amount phi m (degree) (wherein 160 phi m 200),
the correction film has a laminated film obtained by laminating a 1 st film including Cr and O and a 2 nd film including Cr, C and O in an arbitrary order,
the 1 st film contains no C, or contains C in an amount less than that of the 2 nd film,
the 2 nd film contains O in an amount less than that of the 1 st film.
That is, the photomask has a normal translucent portion and a corrected translucent portion to which correction is applied.
Further, the transfer pattern may further include a light shielding portion that does not substantially transmit the exposure light.
In this case, the light shielding portion is formed by forming at least a light shielding film on the transparent substrate, and may have a laminated structure in which a semi-light transmissive film is formed on an upper layer side or a lower layer side of the light shielding film.
The order of lamination of the 1 st film and the 2 nd film of the correction film, the optical properties or composition of each of the 1 st film and the 2 nd film, the optical properties or composition of the correction film formed by lamination, and the like are as described in connection with the above-described photomask correction method.
In the photomask having such a configuration, since the modified semi-transmissive portion is formed to precisely correct the defect generated in the semi-transmissive film 2 having a predetermined transmittance and a predetermined phase shift effect, it is very useful to realize high resolution by the phase shift effect.
As a material of a normal semi-opaque film, a material containing chromium (Cr) or a material containing a transition metal and Si (silicon) is exemplified. For example, Cr or a Cr compound (preferably CrO, CrC, CrN, CrON, or the like), or a material containing Si and at least one of Z (zirconium), Nb (niobium), Hf (hafnium), Ta (tantalum), Mo (molybdenum), and Ti (titanium), or a material composed of an oxide, nitride, oxynitride, carbide, or oxynitride carbide of these materials may be used. More specifically, molybdenum silicon nitride (MoSiN), molybdenum silicide oxynitride (MoSiON), molybdenum silicide oxide (MoSiN), silicon oxynitride (SiON), titanium oxide nitride (TiON), and the like can be cited.
The material of the light-shielding film may be, for example, Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or a silicide of a metal containing Mo, W (tungsten), Ta, or Ti, or the compound of the silicide. The material of the light shielding film is preferably a material that can be wet-etched. It is preferable that the material of the light-shielding film is a material having etching selectivity to the material of the semi-light-transmitting film. That is, the light-shielding film preferably has resistance to an etchant for the semi-light-transmitting film, and further the semi-light-transmitting film preferably has resistance to an etchant for the light-shielding film.
The use of the photomask of the present invention is not particularly limited.
In the present invention, the photomask utilizing the phase shift effect is preferably used for manufacturing a display device including a fine pattern width (CD). The present invention is advantageously used in the case of using a semi-transparent film having a phase shift effect, for example, in a phase shift mask having a hole pattern or the like having a CD (diameter) of 3 μm or less (1.0 to 2.5 μm, and further 1.0 to 2.0 μm for a more highly precise display device) on a transfer target. Alternatively, the present invention may be applied to a line and space pattern having the above-described CD (line width, or space width). In particular, a photomask using a high-transmittance phase shift film, which is an object of the present invention, is a photomask using a semi-transparent film in order to improve the resolution of an isolated pattern. Here, when a plurality of patterns are arranged so as to have a predetermined regularity and a pattern that mutually exerts an optical influence is a dense pattern, a pattern other than the dense pattern is an isolated pattern.
< method for manufacturing device for display device >
The present invention includes a method for manufacturing a device for a display device using the photomask having the above-described structure. The manufacturing method includes a step of exposing the transfer pattern of the photomask to light by an exposure device and transferring the pattern to a transfer object. The exposure device may be a projection type or a proximity type. The former is more advantageous for manufacturing a high-precision device that precisely resolves a minute pattern based on the phase shift effect.
As the optical conditions for performing exposure by using the projection method, the NA (numerical aperture) of the optical system is preferably 0.08 to 0.15, and the exposure light source preferably includes i-rays. Of course, exposure using a wavelength region including i-line to g-line is also possible.
According to the method for manufacturing a device for a display device of the present invention, since the defect of the translucent portion is corrected by using the correction film having the 2-layer structure, it is possible to perform correction so as to have optical properties almost the same as those of the phase shift film having a high transmittance, which is difficult to realize. That is, it is possible to precisely correct a defect generated in the semi-transmissive film having a high transmittance and a phase shift effect. Here, since both the 1 st film and the 2 nd film constituting the correction film can be formed by the laser CVD method, it is not necessary to use a correction device of various types, which is very advantageous particularly in the correction of a photomask for manufacturing a large-sized display device.
< modification example >
The photomask correction method, the photomask manufacturing method, the photomask, and the display device manufacturing method according to the present invention are not limited to the aspects disclosed in the above embodiments, as long as the above-described effects are not lost.
For example, as described above, the present invention is very useful when applied to a photomask used for manufacturing a device for a display device, but the application of the photomask is not particularly limited, and the present invention can also be applied to a photomask for manufacturing a semiconductor device.
The photomask to be applied to the present invention may further include other optical films or functional films in a part of the phase shift film or light shielding film, or in addition to the phase shift film or light shielding film.