阅读说明：本技术 干蚀刻方法、半导体设备的制造方法和蚀刻装置 (Dry etching method, method for manufacturing semiconductor device, and etching apparatus ) 是由 武田雄太 山内邦裕 八尾章史 于 2020-02-19 设计创作，主要内容包括：本发明的干蚀刻方法的特征在于,其是使包含β-二酮的蚀刻气体与形成于被处理体的表面的金属膜接触而蚀刻所述金属膜的干蚀刻方法,所述方法包括：使包含第1β-二酮的第1蚀刻气体与上述金属膜接触的第1蚀刻工序；及在上述第1蚀刻工序之后,使包含第2β-二酮的第2蚀刻气体与上述金属膜接触的第2蚀刻工序,上述第1β-二酮是能够通过与上述金属膜的反应而生成第1络合物的化合物,上述第2β-二酮是能够通过与上述金属膜的反应而生成升华点比上述第1络合物低的第2络合物的化合物。(A dry etching method according to the present invention is a dry etching method for etching a metal film formed on a surface of an object to be processed by bringing an etching gas containing a β -diketone into contact with the metal film, the method including: a 1 st etching step of bringing a 1 st etching gas containing a 1 st β -diketone into contact with the metal film; and a 2 nd etching step of bringing a 2 nd etching gas containing a 2 nd β -diketone into contact with the metal film after the 1 st etching step, wherein the 1 st β -diketone is a compound capable of generating a 1 st complex by a reaction with the metal film, and the 2 nd β -diketone is a compound capable of generating a 2 nd complex having a lower sublimation point than the 1 st complex by a reaction with the metal film.)

1. A dry etching method is characterized in that,

the dry etching method is a dry etching method for etching a metal film formed on a surface of an object to be processed by bringing an etching gas containing a beta-diketone into contact with the metal film, and the method includes:

a 1 st etching step of bringing a 1 st etching gas containing a 1 st β -diketone into contact with the metal film; and

a 2 nd etching step of bringing a 2 nd etching gas containing a 2 nd beta-diketone into contact with the metal film after the 1 st etching step,

the 1 st beta-diketone is a compound capable of forming a 1 st complex by a reaction with the metal film,

the 2 beta-diketone is a compound capable of generating a 2 nd complex having a lower sublimation point than the 1 st complex by a reaction with the metal film.

2. A dry etching method according to claim 1, wherein the combination of the 1 st β -diketone and the 2 nd β -diketone, i.e., the 1 st β -diketone and the 2 nd β -diketone, is acetylacetone and hexafluoroacetylacetone, acetylacetone and trifluoroacetylacetone, or trifluoroacetylacetone and hexafluoroacetylacetone.

3. The dry etching method according to claim 1 or 2, wherein the 1 st etching step and the 2 nd etching step are repeatedly performed.

4. A dry etching method according to any one of claims 1 to 3, wherein the metal film contains at least 1 metal element selected from the group consisting of Zr, Hf, Fe, Mn, Cr, Al, Ru, Co, Cu, Zn, Pt and Ni.

5. A dry etching method according to any one of claims 1 to 4, wherein the 1 st etching gas and the 2 nd etching gas each independently further contain a gas selected from the group consisting of NO, NO₂、N₂O、O₂、O₃、H₂O and H₂O₂At least 1 additive gas of the group.

6. The dry etching method according to claim 1, wherein the metal film contains Co element,

the 1 st etching gas contains acetylacetone as the 1 st beta-diketone and NO as an additive gas,

the 2 nd etching gas contains hexafluoroacetylacetone as the 2 nd β -diketone and NO as an additive gas.

7. A dry etching method according to any one of claims 1 to 6, wherein the 1 st etching gas and the 2 nd etching gas each independently further contain a gas selected from the group consisting of N₂And at least 1 inert gas of the group consisting of Ar, He, Ne and Kr.

8. The dry etching method according to any one of claims 1 to 7, further comprising: and a pretreatment step of supplying a reducing gas to the metal film before the 1 st etching step.

9. A method for manufacturing a semiconductor device, comprising a step of etching a metal film on a substrate by the dry etching method according to any one of claims 1 to 8.

10. An etching apparatus, comprising:

a mounting part which is provided in a heatable processing container and mounts an object to be processed having a metal film formed on a surface thereof;

a 1 β -diketone supplying unit that supplies a 1 β -diketone to the object to be treated, the 1 β -diketone being a compound capable of generating a 1 st complex by a reaction with the metal film;

a 2 β -diketone supplying unit that supplies a 2 β -diketone to the object to be treated, the 2 β -diketone being a compound capable of generating a 2 nd complex having a lower sublimation point than the 1 st complex by a reaction with the metal film; and

and a control unit that outputs a control signal for performing a 1 st step of supplying a 1 st etching gas containing the 1 st β -diketone to the object to be processed and a 2 nd step of supplying a 2 nd etching gas containing the 2 nd β -diketone to the object to be processed after the 1 st step.

11. The etching apparatus according to claim 10, further comprising a reducing gas supply unit configured to supply a reducing gas to the object to be processed,

the control unit outputs a control signal for supplying the reducing gas to the object to be processed before supplying the 1 st etching gas to the object to be processed.

Technical Field

The invention relates to a dry etching method, a method for manufacturing a semiconductor device, and an etching apparatus.

Background

In a manufacturing process of a semiconductor device, a metal film formed on a substrate may be etched as a wiring material, a metal gate material, an electrode material, or a magnetic material.

With the miniaturization of semiconductor devices, it has been required to highly control the etching of a metal film in order to etch the metal film to form a fine structure. Specifically, the following were studied: etching the metal film so that variations in the amount of etching in the wafer surface are suppressed to 1nm or less, controlling roughness of the surface of the metal film after etching, selectively etching the metal film, and the like. In order to perform such high degree of etching control, wet etching by etching a metal film with a chemical solution is difficult, and dry etching by etching a metal film with a gas is studied.

Patent document 1 describes an etching method including the following etching steps: a thin film formed on a substrate is etched at a substrate temperature of 300 ℃ or higher, preferably 450 ℃ or higher, by an etching gas containing a beta-diketone and at least one of water and alcohol, thereby exposing the surface of the substrate. Patent document 2 describes the following method: a metal film is etched by forming a complex of a beta-diketone and a metal in a temperature range of 100 ℃ to 350 ℃ using an etching gas containing the beta-diketone and 1 to 20 vol% of water or hydrogen peroxide. Patent document 2 discloses examples of metals constituting the metal film, including zinc, cobalt, hafnium, iron, manganese, and vanadium. According to patent document 2, the rate of etching the metal film is increased by adding water or hydrogen peroxide compared to the case of using oxygen.

Although not a method of finely etching a metal film on a substrate, a method using β -diketone has been proposed as a method of dry-cleaning a metal film attached to a film forming apparatus used in a manufacturing process of a semiconductor device.

Patent document 3 describes a dry cleaning method in which beta-diketone and NOx (NO, N) are included₂O) is reacted with the metal film at a temperature of 200 to 400 ℃, preferably 250 to 370 ℃, thereby removing the metal film attached to the film forming apparatus. Patent document 3 discloses examples of metals constituting the metal film, including nickel, manganese, iron, and cobalt. According to patent document 3, the use of NOx expands the temperature range in which the metal film can be etched and removed, compared with the case of using oxygen.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2004-91829

Patent document 2: japanese patent laid-open No. 2014-236096

Patent document 3: japanese patent laid-open publication Nos. 2013-194307

Disclosure of Invention

Problems to be solved by the invention

The crystallinity of a metal film to be etched differs depending on the film formation method, but is often a polycrystalline film formed by aggregation of crystal grains. When such a metal film is etched by the methods described in patent documents 1 to 3, it is very difficult to uniformly etch the entire metal film. In general, the relatively weak (i.e., highly reactive) grain boundaries are preferentially etched, and thus it is considered that the surface roughness occurs in the film after etching due to the difference in etching rate. In recent years, with the progress of miniaturization, even minute surface roughness has become a considerable problem, and improvement thereof is required.

When the metal film is etched using an etching gas containing a β -diketone, the metal and the β -diketone form a complex, whereby the metal film is etched. Since the metal needs to be oxidized at one time to form the complex, an oxidizing agent such as oxygen or the above-mentioned NOx is often added to the etching gas. The present inventors have conventionally attempted to improve surface roughness by adjusting the amount of an oxidizing agent to be added, the timing of addition, and the treatment conditions when using a β -diketone, but they have not been able to fundamentally improve the surface roughness.

The present invention has been made in view of the above problems, and an object thereof is to provide a dry etching method capable of suppressing surface roughness of a metal film. Further, another object of the present invention is to provide a method for manufacturing a semiconductor device using the above dry etching method. It is another object of the present invention to provide an etching apparatus capable of suppressing the occurrence of surface roughness of a metal film.

Means for solving the problems

The present inventors have focused on the fact that the sublimation point of a complex formed in a reaction with a metal greatly differs depending on the type of β -diketone. Further, it was found that: the present inventors have completed the present invention by improving the surface roughness of a metal film when the metal film is treated with a 1 st beta-diketone which generates a 1 st complex having a high sublimation point and then treated with a 2 nd beta-diketone which generates a 2 nd complex having a lower sublimation point than the 1 st complex.

A dry etching method according to the present invention is a dry etching method for etching a metal film formed on a surface of an object to be processed by bringing an etching gas containing a β -diketone into contact with the metal film, the method including: a 1 st etching step of bringing a 1 st etching gas containing a 1 st β -diketone into contact with the metal film; and a 2 nd etching step of bringing a 2 nd etching gas containing a 2 nd β -diketone into contact with the metal film after the 1 st etching step, wherein the 1 st β -diketone is a compound capable of generating a 1 st complex by a reaction with the metal film, and the 2 nd β -diketone is a compound capable of generating a 2 nd complex having a lower sublimation point than the 1 st complex by a reaction with the metal film.

In the dry etching method of the present invention, the combination of the 1 st β -diketone and the 2 nd β -diketone is preferably (1 st β -diketone, 2 nd β -diketone) ═ (acetylacetone, hexafluoroacetylacetone), (acetylacetone, trifluoroacetylacetone), or (trifluoroacetylacetone, hexafluoroacetylacetone).

In the dry etching method of the present invention, the 1 st etching step and the 2 nd etching step may be repeated.

In the dry etching method of the present invention, the metal film preferably contains at least 1 metal element selected from the group consisting of Zr, Hf, Fe, Mn, Cr, Al, Ru, Co, Cu, Zn, Pt and Ni.

In the dry etching method of the present invention, it is preferable that the 1 st etching gas and the 2 nd etching gas each independently further contain NO or NO₂、N₂O、O₂、O₃、H₂O and H₂O₂At least 1 additive gas of the group.

In the dry etching method of the present invention, it is preferable that: the metal film contains a Co element, the 1 st etching gas contains acetylacetone as the 1 st β -diketone and NO as an additive gas, and the 2 nd etching gas contains hexafluoroacetylacetone as the 2 nd β -diketone and NO as an additive gas.

In the dry etching method of the present invention, it is preferable that the 1 st etching gas and the 2 nd etching gas each independently further contain N₂And at least 1 inert gas of the group consisting of Ar, He, Ne and Kr.

The dry etching method of the present invention preferably further comprises: and a pretreatment step of supplying a reducing gas to the metal film before the 1 st etching step.

The method for manufacturing a semiconductor device of the present invention includes a step of etching a metal film on a substrate by the dry etching method of the present invention.

An etching apparatus according to the present invention is characterized by comprising: a mounting part which is provided in a heatable processing container and mounts an object to be processed having a metal film formed on a surface thereof; a 1 β -diketone supplying unit that supplies a 1 β -diketone to the object to be treated, the 1 β -diketone being a compound capable of generating a 1 st complex by a reaction with the metal film; a 2 β -diketone supplying unit configured to supply a 2 β -diketone to the object to be treated, the 2 β -diketone being a compound capable of generating a 2 nd complex having a lower sublimation point than the 1 st complex by a reaction with the metal film; and a control unit that outputs a control signal for performing a 1 st step of supplying a 1 st etching gas containing the 1 st β -diketone to the object to be processed and a 2 nd step of supplying a 2 nd etching gas containing the 2 nd β -diketone to the object to be processed after the 1 st step.

The etching apparatus of the present invention further includes a reducing gas supply unit configured to supply a reducing gas to the object to be processed, and the control unit preferably outputs a control signal for supplying the reducing gas to the object to be processed before the 1 st etching gas is supplied to the object to be processed.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a dry etching method capable of suppressing surface roughness of a metal film can be provided.

Drawings

Fig. 1 is a schematic view schematically showing an etching apparatus according to an embodiment of the present invention.

Fig. 2 is a flow chart showing the experimental procedures of example 1 and example 2.

Fig. 3 is a flowchart showing the test procedure of comparative example 1.

Fig. 4 is a graph showing the relationship between the etching amount and the RMS in example 1 and comparative example 1.

Fig. 5 is a graph showing the relationship between the etching amount and the RMS in example 1 and example 2.

Detailed Description

Hereinafter, embodiments of the present invention will be specifically described.

However, the present invention is not limited to the following embodiments, and can be applied by appropriately changing the embodiments without changing the gist of the present invention.

[ Dry etching method ]

The dry etching method according to an embodiment of the present invention is a method of etching a metal film formed on a surface of an object to be processed by bringing an etching gas containing a β -diketone into contact with the metal film. When an etching gas containing a beta-diketone is brought into contact with a metal film in a heated state, the beta-diketone reacts with the metal film to form a complex. Since the complex has a high vapor pressure, the metal film can be removed by vaporizing the complex.

The dry etching method according to an embodiment of the present invention is characterized in that after the 1 st etching step of bringing the 1 st etching gas containing the 1 st β -diketone into contact with the metal film, the 2 nd etching step of bringing the 2 nd etching gas containing the 2 nd β -diketone into contact with the metal film is performed, the 1 st β -diketone can generate the 1 st complex having a high sublimation point, and the 2 nd β -diketone can generate the 2 nd complex having a lower sublimation point than the 1 st complex.

This can suppress surface roughness of the metal film after etching. The mechanism is presumed as follows. First, when a metal film is treated with a 1 β -diketone, the 1 β -diketone preferentially forms a complex with respect to a grain boundary having a relatively weak bond (i.e., high reactivity). Next, when the metal film is treated with the 2 β -diketone, the complex formed in the 1 β -diketone acts as a protective film in the grain boundary, and thus the 2 β -diketone attacks the crystal grain portion having relatively low reactivity. Then, as the etching of the grains proceeds, the protected grain boundaries are also etched. As a result, it is considered that the entire metal film is uniformly etched.

The metal film to be subjected to the dry etching method according to the embodiment of the present invention is formed of a metal element capable of forming a complex with a β -diketone. Specifically, at least 1 metal element selected from the group consisting of Zr, Hf, Fe, Mn, Cr, Al, Ru, Co, Cu, Zn, Pt and Ni is exemplified. The metal film may be a metal film composed of only 1 metal element, or may be a metal film composed of a plurality of metal elements. Among them, the dry etching method according to one embodiment of the present invention is effective for a metal film containing a Co element. In the dry etching method according to the embodiment of the present invention, a substrate such as a known semiconductor substrate or glass substrate can be used as a base material of the object to be processed.

(etching step 1)

The 1 st etching gas contains a 1 st beta-diketone. The kind of the 1. beta. -diketone is not particularly limited depending on the relationship with the 2. beta. -diketone, and examples thereof include acetylacetone, trifluoroacetylacetone, and the like. As the 1 β -diketone, 1 kind of compound may be used, and 2 or more kinds of compounds may be used.

From the viewpoint of obtaining a sufficient etching rate, the content of the 1 st β -diketone contained in the 1 st etching gas is preferably 10% by volume or more and 90% by volume or less, and more preferably 30% by volume or more and 60% by volume or less.

The 1 st etching gas preferably further comprises a gas selected from the group consisting of NO and NO₂、N₂O、O₂、O₃、H₂O and H₂O₂At least 1 additive gas of the group.

When the 1 st etching gas contains the additive gas, the content of the additive gas contained in the 1 st etching gas is preferably 0.01 vol% or more and 10 vol% or less, more preferably 0.05 vol% or more and 8 vol% or less, and further preferably 0.1 vol% or more and 5 vol% or less, from the viewpoint of obtaining a sufficient etching rate.

The 1 st etching gas preferably further contains a gas selected from the group consisting of N₂And at least 1 inert gas of the group consisting of Ar, He, Ne and Kr.

When the 1 st etching gas contains an inert gas, the content of the inert gas contained in the 1 st etching gas is preferably 1 vol% or more and 90 vol% or less, more preferably 10 vol% or more and 80 vol% or less, and still more preferably 30 vol% or more and 50 vol% or less.

(etching step 2)

The 2 nd etching gas contains a 2 nd beta-diketone. The type of the 2 β -diketone is not particularly limited depending on the relationship with the 1 β -diketone, and examples thereof include hexafluoroacetylacetone and trifluoroacetylacetone. As the 2 β -diketone, 1 kind of compound may be used, and 2 or more kinds of compounds may be used.

Examples of the combination of the 1 st β -diketone and the 2 nd β -diketone include (1 st β -diketone, 2 nd β -diketone) ═ e.g. (acetylacetone, hexafluoroacetylacetone), (acetylacetone, trifluoroacetylacetone), (trifluoroacetylacetone, hexafluoroacetylacetone), and the like.

From the viewpoint of obtaining a sufficient etching rate, the content of the 2 nd β -diketone contained in the 2 nd etching gas is preferably 10% by volume or more and 90% by volume or less, and more preferably 30% by volume or more and 60% by volume or less.

The 2 nd etching gas preferably further contains a gas selected from the group consisting of NO and NO₂、N₂O、O₂、O₃、H₂O and H₂O₂At least 1 additive gas of the group. When the 1 st etching gas and the 2 nd etching gas contain additive gases, the additive gas contained in the 1 st etching gas may be the same as or different from the additive gas contained in the 2 nd etching gas.

When the 2 nd etching gas contains the additive gas, the content of the additive gas contained in the 2 nd etching gas is preferably 0.01 vol% or more and 10 vol% or less, more preferably 0.05 vol% or more and 8 vol% or less, and further preferably 0.1 vol% or more and 5 vol% or less, from the viewpoint of obtaining a sufficient etching rate. When the 1 st etching gas and the 2 nd etching gas contain additive gases, the content of the additive gas contained in the 1 st etching gas may be the same as or different from the content of the additive gas contained in the 2 nd etching gas.

The 2 nd etching gas preferably further contains a gas selected from the group consisting of N₂And at least 1 inert gas of the group consisting of Ar, He, Ne and Kr. When the 1 st etching gas and the 2 nd etching gas contain an inactive gas, the inactive gas and the 1 st etching gas contained in the 1 st etching gas2 the inert gas contained in the etching gas may be the same or different.

When the 2 nd etching gas contains an inert gas, the content of the inert gas contained in the 2 nd etching gas is preferably 1 vol% or more and 90 vol% or less, more preferably 10 vol% or more and 80 vol% or less, and still more preferably 30 vol% or more and 50 vol% or less. When the 1 st etching gas and the 2 nd etching gas contain an inert gas, the content of the inert gas contained in the 1 st etching gas may be the same as or different from the content of the inert gas contained in the 2 nd etching gas.

In the dry etching method according to the embodiment of the present invention, the 1 st etching step and the 2 nd etching step may be repeated. In this case, the conditions in the 1 st etching step may be the same or different. Similarly, the conditions in the 2 nd etching step may be the same or different.

(pretreatment step)

In the dry etching method according to the embodiment of the present invention, it is preferable to perform a pretreatment step of supplying a reducing gas to the metal film before the 1 st etching step. For example, when the metal film to be removed contains Co element, variation in etching rate due to the thickness of the natural oxide film can be improved by reducing the natural oxide film of cobalt.

In the pretreatment step, as the reducing gas, for example, hydrogen (H) gas can be used₂) Carbon monoxide (CO), formaldehyde (HCHO), and the like. The reducing gas may be only 1 kind, or 2 or more kinds.

In the pretreatment step, only H may be supplied₂Reducing gas such as gas, or N as described above₂The inert gas such as gas dilutes the reducing gas.

In the pretreatment step, it is preferable that the β -diketone and the additive gas are not supplied. Specifically, the proportions of the amount of the β -diketone and the additive gas relative to the total amount of the supplied gas in the pretreatment step are preferably less than 0.01 vol%, more preferably less than 0.001 vol%, and particularly preferably 0 vol%, respectively.

[ etching apparatus ]

The dry etching method according to an embodiment of the present invention can be realized by using a general etching apparatus used in a semiconductor manufacturing process, for example. Such an etching apparatus is also one of the embodiments of the present invention.

Fig. 1 is a schematic view schematically showing an etching apparatus according to an embodiment of the present invention.

The etching apparatus 100 shown in fig. 1 includes: a processing container 110 for disposing a target object 10 having a metal film formed on a surface thereof; a 1 beta-diketone supply section 130 connected to the treatment vessel 110 and supplying a 1 beta-diketone; a 2 β -diketone supply section 140 for supplying a 2 β -diketone; an additive gas supply unit 150 for supplying an additive gas; an inert gas supply unit 160 for supplying an inert gas; a reducing gas supply unit 170 for supplying a reducing gas; and a heating device 180 for heating the processing container 110. A gas flow rate control unit (not shown) is connected to the 1 β -diketone supply unit 130 and the like, and outputs a valve control signal to supply the 1 β -diketone and the like to the object 10. The etching apparatus 100 may further include an additive gas supply unit 150, an inert gas supply unit 160, and a reducing gas supply unit 170.

The processing container 110 includes a mounting portion 111 for mounting the object 10. The processing container 110 is not particularly limited as long as it has resistance to the beta-diketone used and can be reduced to a predetermined pressure, and a general processing container or the like provided in a semiconductor etching apparatus can be used. Further, a general-purpose gas supply pipe, other piping, and the like for supplying an etching gas may be used without particular limitation as long as they have resistance to β -diketone.

The 1 st beta-diketone supply section 130 adjusts the supply amount by the valves V1 to V5 and the flow regulator MFC1 to supply N₂The bubbling gas is supplied from the pipes 131, 132, and 133 to the 1 st β -diketone container 137, and the 1 st β -diketone is supplied from the 1 st β -diketone container 137 to the pipes 134, 135, and 121. In fig. 1, the pipe 133 and the pipe 134 are connected by the pipe 136, but the pipe 136 may not be provided.

The 2 β -diketone supply section 140 adjusts the supply amount by valves V6 and V7 and the flow regulator MFC2, and supplies the 2 β -diketone to the pipe 121 through pipes 141 and 142.

The additive gas supply unit 150 adjusts the supply amount by valves V8 and V9 and the flow regulator MFC3, and supplies additive gas to the pipe 121 through pipes 151 and 152.

The inert gas supply unit 160 adjusts the supply amount by valves V10 and V11 and the flow regulator MFC4, and supplies the inert gas to the pipe 121 through pipes 161 and 162.

The reducing gas supply unit 170 adjusts the supply amount by valves V12 and V13 and the flow regulator MFC5, and supplies the reducing gas to the pipe 121 through the pipes 171 and 172.

In the etching apparatus 100, as for the β -diketone, it is preferable that: the inert gas supplied from the inert gas supply unit 160 is diluted to a predetermined concentration and supplied to the processing container 110 in a state of being mixed with the additive gas supplied from the gas-containing gas supply unit 150 at a predetermined concentration. However, the beta-diketone may also be diluted without an inert gas.

A heating device 180 for heating the processing container 110 is disposed outside the processing container 110. In addition, a heater (not shown) may be disposed as the 2 nd heating device inside the mounting portion 111. In the case where a plurality of placement units are disposed in the processing container 110, the placement units can be set to a predetermined temperature by providing a heater for each placement unit.

A gas exhaust device for exhausting the reacted gas may be provided at one side of the process container 110. The reacted gas is exhausted from the processing chamber 110 through the pipe 181 by the vacuum pump 183 of the gas exhaust device. The gas after the reaction can be recovered by a liquid nitrogen trap 184 provided between the pipe 181 and the pipe 182. Valves V14 and V15 are provided in the pipes 181 and 182, respectively, to adjust the pressure. In fig. 1, PI1 and PI2 are pressure gauges, and the control unit can control the flow rate control devices and the valves based on the indicated values.

An etching method will be described specifically by taking the etching apparatus 100 as an example.

An object to be treated 10 is disposed in the treatment container 110, and a metal film containing a metal element capable of forming a complex with a β -diketone is formed on the object to be treated 10. The vacuum inside the processing container 110, the pipe 121, the pipes 131 to 136, the pipes 141 and 142, the pipes 151 and 152, the pipes 161 and 162, the pipes 171 and 172, the liquid nitrogen trap 184, and the pipes 181 and 182 is replaced with a predetermined pressure by the vacuum pump 183, and then the object 10 is heated by the heating device 180. After reaching a predetermined temperature, the 1 st β -diketone, the additive gas and the inert gas are supplied to the pipe 121 at a predetermined flow rate from the 1 st β -diketone supplying section 130, the additive gas supplying section 150 and the inert gas supplying section 160.

The diluted 1 st β -diketone and the additive gas are mixed with a predetermined composition and supplied to the processing container 110. The inside of the processing container 110 is controlled to a predetermined pressure while introducing the mixed 1 st etching gas into the processing container 110. The 1 st etching step is performed by reacting the 1 st etching gas with the metal film for a predetermined time. In the 1 st etching step, etching can be performed without plasma, and it is not necessary to excite an etching gas with plasma or the like in etching.

After the 1 st etching step, vacuum replacement is performed again. Then, the 2 β -diketone, the additive gas, and the inert gas are supplied to the pipe 121 at predetermined flow rates from the 2 β -diketone supplying section 140, the additive gas supplying section 150, and the inert gas supplying section 160.

The diluted 2 β -diketone and the additive gas are mixed with a predetermined composition and supplied to the processing container 110. The inside of the processing container 110 is controlled to a predetermined pressure while introducing the mixed 2 nd etching gas into the processing container 110. The 2 nd etching step is performed by reacting the 2 nd etching gas with the metal film for a predetermined time. In the 2 nd etching step, etching can be performed without plasma, and it is not necessary to excite an etching gas with plasma or the like in etching.

When the 1 st etching step and the 2 nd etching step are repeated, after the 2 nd etching step is completed, vacuum replacement is performed again. Then, the 1 st etching step and the 2 nd etching step are performed in the same manner as described above.

After the etching step 2 is completed, the heating by the heating device 180 is stopped and the temperature is lowered, and the vacuum pump 183 is stopped to release the vacuum. The etching of the metal film can be performed by the above operation.

Before the 1 st etching step, the pretreatment step may be performed by supplying the reducing gas to the object 10 through the reducing gas supply unit 170. It is preferable to perform vacuum replacement after the pretreatment process and before the 1 st etching process.

(etching conditions)

In the dry etching method according to one embodiment of the present invention, the temperature at which the 1 st etching step and the 2 nd etching step are performed may be a temperature at which the complex is vaporized, and particularly, the temperature of the metal film to be removed is preferably 100 ℃ or higher and 350 ℃ or lower, and more preferably 130 ℃ or higher and 250 ℃ or lower. The temperature of the metal film may be the same as or different from that of the 1 st etching step and the 2 nd etching step.

The pressure in the processing container in the 1 st etching step and the 2 nd etching step is not particularly limited, and is usually in a pressure range of 0.1kPa to 101.3 kPa. The pressure in the processing container may be the same as or different from that in the 1 st etching step and the 2 nd etching step.

In particular, when the metal film to be removed contains a Co element, the 1 st etching gas contains acetylacetone as a 1 st β -diketone and NO as an additive gas, and the 2 nd etching gas contains hexafluoroacetylacetone as a 2 nd β -diketone and NO as an additive gas, when etching is performed at a high temperature of about 300 to 400 ℃, hexafluoroacetylacetone may decompose to form a carbon film, which may damage the structure of the device. Therefore, the object to be treated is preferably heated to 250 ℃ or lower.

As the temperature range, from the viewpoint of obtaining a sufficient etching rate, the pressure in the processing container in the 1 st etching step is preferably 20 torr or more and 300 torr or less (2.67kPa or more and 39.9kPa or less), more preferably 20 torr or more and 100 torr or less (2.67kPa or more and 13.3kPa or less), and still more preferably 20 torr or more and 50 torr or less (2.67kPa or more and 6.67kPa or less). The pressure in the processing chamber in the 2 nd etching step is preferably 20 torr or more and 300 torr or less (2.67kPa or more and 39.9kPa or less), more preferably 50 torr or more and 250 torr or less (6.67kPa or more and 33.3kPa or less), and still more preferably 100 torr or more and 200 torr or less (13.3kPa or more and 26.7kPa or less).

The processing time in the 1 st etching step and the 2 nd etching step is not particularly limited, but is preferably within 60 minutes in view of the efficiency of the semiconductor device manufacturing process. Here, the treatment time in each etching step is: the etching gas is introduced into a processing container in which an object to be processed is placed, and the etching gas in the processing container is exhausted by a vacuum pump or the like to complete the etching process.

When the pretreatment step is performed, the treatment temperature in the pretreatment step is not particularly limited as long as it is a temperature at which the natural oxide film can be reduced, and when the treatment temperature in the pretreatment step is low, the reduction reaction hardly proceeds. The treatment temperature in the pretreatment step may be high, but is preferably the same as that in the 1 st etching step from the viewpoint of the operation of the etching apparatus. From the above, in the pretreatment step, the object to be treated is preferably heated to 100 ℃ or higher and 350 ℃ or lower, and more preferably heated to 150 ℃ or higher and 250 ℃ or lower.

In the pretreatment step, the flow rate of the reducing gas depends on the volume of the treatment vessel. In the pretreatment step, the pressure in the treatment vessel is not particularly limited, and may be set appropriately in the range of 10 to 500 torr (1.33 to 66.5kPa), for example, depending on the apparatus.

The treatment time in the pretreatment step can be appropriately adjusted according to the method of forming a metal film on a substrate, and the like.

[ method for manufacturing semiconductor device ]

The dry etching method according to one embodiment of the present invention can be used as an etching method for forming a predetermined pattern on a metal film of an existing semiconductor device. By etching the metal film on the substrate by the dry etching method according to one embodiment of the present invention, a semiconductor device can be manufactured at low cost.

Examples of such semiconductor devices include solar cells, hard disk drives, dynamic random access memories, phase change memories, ferroelectric memories, magnetoresistive memories, resistive memories, Micro Electro Mechanical Systems (EMS), and the like.

Examples

In the following, embodiments of the present invention are shown to be disclosed in more detail. The present invention is not limited to these examples.

In example 1, example 2 and comparative example 1, a cobalt film (shape 1cm × 1cm, film thickness 200nm) formed on the surface of a silicon wafer was etched using the etching apparatus 100 shown in fig. 1.

Fig. 2 is a flow chart showing the experimental procedures of example 1 and example 2. Fig. 3 is a flowchart showing the test procedure of comparative example 1. In fig. 2 and 3, Vac represents vacuum displacement.

(example 1)

The interior of the processing container 110, the piping 121, the pipings 131 to 136, the pipings 141 and 142, the pipings 151 and 152, the pipings 161 and 162, the pipings 171 and 172, the liquid nitrogen collector 184, and the pipings 181 and 182 is vacuum-replaced to less than 10 Pa. Then, the object 10 to be processed, which is placed on the placing portion 111 and whose weight has been measured, is heated by the heating device 180 and the heater disposed inside the placing portion 111. After confirming that the heating device 180 and the heater disposed inside the mounting part 111 reached 200 ℃, the heating device was supplied at 50 torr for 10 minutes H by the reducing gas supply part 170₂The gas was 10sccm, and a pretreatment step was performed.

After the pretreatment step, the pressure was again replaced by vacuum to less than 10 Pa. Then, acetylacetone (Acac) is supplied from the 1 st β -diketone supply unit 130, NO gas is supplied from the additive gas supply unit 150, and N is supplied from the inert gas supply unit 160 at predetermined flow rates₂The gas is supplied to the pipe 121, and the 1 st etching gas is introduced into the processing container 110, and the pressure inside the processing container 110 is controlled to 21 torr, thereby performing the 1 st etching step. The temperature of the object to be processed was 200 ℃ and the flow rate of the 1 st etching gas was Acac/NO/N₂10/1/10 sccm. Stopping the introduction of the etching gas 1 st after 1-5 minutes from the start of the introduction of the etching gas 1 stEtching gas No. 1.

After the 1 st etching step, the film was again vacuum-replaced to less than 10 Pa. Then, hexafluoroacetylacetone (HFAc) is supplied from the 2. beta. -diketone supply unit 140, NO gas is supplied from the additive gas supply unit 150, and N is supplied from the inert gas supply unit 160 at predetermined flow rates₂The 2 nd etching process was performed by supplying the 2 nd etching gas to the pipe 121 while controlling the pressure inside the process container 110 to 100 torr while introducing the 2 nd etching gas into the process container 110. The temperature of the object to be processed was 200 ℃ and the flow rate of the No. 2 etching gas was HFAc/NO/N₂50/1/49 sccm. After 1-5 minutes from the start of the introduction of the 2 nd etching gas, the introduction of the 2 nd etching gas is stopped.

Repeating the 1 st etching step and the 2 nd etching step for 1-8 cycles.

(example 2)

The object to be processed was etched by performing the pretreatment step, the 1 st etching step, and the 2 nd etching step in the same manner as in example 1 except that the temperature of the object to be processed was changed to 150 ℃.

Comparative example 1

First, the pretreatment step was performed under the same conditions as in example 1.

After the pretreatment step, the pressure was again replaced by vacuum to less than 10 Pa. Then, hexafluoroacetylacetone (HFAc) is supplied from the 2. beta. -diketone supply unit 140, NO gas is supplied from the additive gas supply unit 150, and N is supplied from the inert gas supply unit 160 at predetermined flow rates₂The etching process was performed by supplying the etching gas to the pipe 121, and controlling the pressure inside the processing container 110 to 100 torr while introducing the etching gas into the processing container 110. The temperature of the object to be processed was 200 ℃ and the flow rate of the etching gas was HFAc/NO/N₂50/1/49 sccm. After 2 to 60 minutes from the start of the introduction of the etching gas, the introduction of the etching gas is stopped.

In example 3 and comparative example 2, the etching apparatus 100 shown in fig. 1 was used to etch an iron film (shape 1cm × 1cm, film thickness 200nm) formed on the surface of a silicon wafer.

(example 3)

First, the pretreatment step was performed under the same conditions as in example 1.

After the pretreatment step, the pressure was again replaced by vacuum to less than 10 Pa. Then, acetylacetone (Acac) was supplied from the 1 st β -diketone supply unit 130, and H was supplied from the additive gas supply unit 150₂O gas and N gas supplied from inert gas supply part 160₂The gas is supplied to the pipe 121, and the 1 st etching process is performed while the 1 st etching gas is introduced into the processing container 110 and the pressure inside the processing container 110 is controlled to 21 torr. The temperature of the object to be processed was 250 ℃ and the flow rate of the 1 st etching gas was Acac/H₂O/N₂10/1/10 sccm. After 1-5 minutes from the start of the introduction of the 1 st etching gas, the introduction of the 1 st etching gas is stopped.

After the 1 st etching step, the film was again vacuum-replaced to less than 10 Pa. Hexafluoroacetylacetone (HFAc) was supplied from the 2. beta. -diketone supply unit 140 and H was supplied from the additive gas supply unit 150 at predetermined flow rates₂O gas and N gas supplied from inert gas supply part 160₂The 2 nd etching process was performed by supplying the 2 nd etching gas to the pipe 121 while controlling the pressure inside the process container 110 to 100 torr while introducing the 2 nd etching gas into the process container 110. The temperature of the object to be processed was 250 ℃ and the flow rate of the 2 nd etching gas was HFAc/H₂O/N₂50/1/49 sccm. After 1-5 minutes from the start of the introduction of the 2 nd etching gas, the introduction of the 2 nd etching gas is stopped.

Repeating the 1 st etching step and the 2 nd etching step for 1-8 cycles.

Comparative example 2

First, the pretreatment step was performed under the same conditions as in example 1.

After the pretreatment step, the pressure was again replaced by vacuum to less than 10 Pa. Hexafluoroacetylacetone (HFAc) was supplied from the 2. beta. -diketone supply unit 140 and H was supplied from the additive gas supply unit 150 at predetermined flow rates₂O gas and N gas supplied from inert gas supply part 160₂The etching process was performed by supplying the etching gas to the pipe 121, and controlling the pressure inside the processing container 110 to 100 torr while introducing the etching gas into the processing container 110. The temperature of the object to be processed was 250 ℃ and the flow rate of the etching gas was set toHFAc/H₂O/N₂50/1/49 sccm. After 2 to 60 minutes from the start of the introduction of the etching gas, the introduction of the etching gas is stopped.

In example 4 and comparative example 3, the etching apparatus 100 shown in fig. 1 was used to etch a hafnium film (shape 1cm × 1cm, film thickness 200nm) formed on the surface of a silicon wafer.

(example 4)

First, the pretreatment step was performed under the same conditions as in example 1.

After the pretreatment step, the pressure was again replaced by vacuum to less than 10 Pa. Then, acetylacetone (Acac) is supplied from the 1 st β -diketone supply unit 130, and NO is supplied from the additive gas supply unit 150₂Gas and N supplied from inert gas supply unit 160₂The first etching gas 1 was introduced into the processing container 110 through the pipe 121, and the first etching step was performed while controlling the pressure inside the processing container 110 to 21 torr. The temperature of the object to be processed was 300 ℃ and the flow rate of the 1 st etching gas was Acac/NO₂/N₂10/1/10 sccm. After 1-5 minutes from the start of the introduction of the 1 st etching gas, the introduction of the 1 st etching gas is stopped.

After the 1 st etching step, the film was again vacuum-replaced to less than 10 Pa. Hexafluoroacetylacetone (HFAc) is supplied from the 2. beta. -diketone supply unit 140 and NO is supplied from the additive gas supply unit 150 at predetermined flow rates₂Gas and N supplied from inert gas supply unit 160₂The 2 nd etching process was performed by supplying the 2 nd etching gas to the pipe 121 while controlling the pressure inside the process container 110 to 100 torr while introducing the 2 nd etching gas into the process container 110. The temperature of the object to be processed was 300 ℃ and the flow rate of the No. 2 etching gas was HFAc/NO₂/N₂50/1/49 sccm. After 1-5 minutes from the start of the introduction of the 2 nd etching gas, the introduction of the 2 nd etching gas is stopped.

Repeating the 1 st etching step and the 2 nd etching step for 1-8 cycles.

Comparative example 3

First, the pretreatment step was performed under the same conditions as in example 1.

After the pretreatment process is finished, the method is true againEmpty to less than 10 Pa. Hexafluoroacetylacetone (HFAc) is supplied from the 2. beta. -diketone supply unit 140 and NO is supplied from the additive gas supply unit 150 at predetermined flow rates₂Gas and N supplied from inert gas supply unit 160₂The etching process was performed by supplying the etching gas into the processing container 110 through the pipe 121 while controlling the pressure inside the processing container 110 to 100 torr. The temperature of the object to be processed was 300 ℃ and the flow rate of the etching gas was HFAc/NO₂/N₂50/1/49 sccm. After 2 to 60 minutes from the start of the introduction of the etching gas, the introduction of the etching gas is stopped.

In examples 1 to 4 and comparative examples 1 to 3, the interior of the processing container 110 was opened to vacuum, and then the object 10 was taken out and the weight thereof was measured. The etching amount is calculated by calculating the volume based on the weight change of the object 10 before and after the test and the density of the cobalt film, iron film, or hafnium film, and dividing the volume by the area of the cobalt film, iron film, or hafnium film.

In examples 1 to 4 and comparative examples 1 to 3, the unevenness of the surface of the cobalt film, iron film or hafnium film after etching was measured by AFM (model SPM-9700 manufactured by SHIMADZU corporation). The root mean square Roughness (RMS) of the AFM-based measurement values was obtained as an index of the surface roughness.

The etching conditions in examples 1 to 4 and comparative examples 1 to 3 are shown in table 1. Table 1 shows the results of determining the slope of RMS with respect to the etching amount.

[ Table 1]

Fig. 4 is a graph showing the relationship between the etching amount and the RMS in example 1 and comparative example 1.

When the RMS slope with respect to the etching amount is obtained from fig. 4, comparative example 1 is 0.095, and example 1 is reduced to 0.063. From the results of fig. 4, it was confirmed that the surface roughness after etching was suppressed in example 1.

Fig. 5 is a graph showing the relationship between the etching amount and the RMS in example 1 and example 2.

When the slope of RMS with respect to the etching amount was calculated from fig. 5, example 1 having an etching temperature of 200 ℃ was 0.063, and example 2 having an etching temperature of 150 ℃ was 0.058. From the results of fig. 5, it was confirmed that there was almost no temperature dependence. Since the etching rates in the 1 st etching step and the 2 nd etching step are both decreased with the decrease in the etching temperature, it is considered that the difference in the etching rates is also maintained.

As shown in table 1, when the etched film was an iron film, the film was 0.102 in comparative example 2, and the film was reduced to 0.082 in example 3. Similarly, when the film to be etched is a hafnium film, the film of comparative example 3 is 0.113, and the film of example 4 is reduced to 0.076. From these results, it was confirmed that the surface roughness after etching was also suppressed in examples 3 and 4.

From the above results, it is considered that the etching proceeds by the above-described presumed mechanism.

The present application claims priority based on the paris convention or the regulations for entering the country based on japanese patent application No. 2019-037591, applied on 3/1/2019. The content of this application is incorporated by reference in its entirety into the present application.

Description of the reference numerals

10 object to be processed

100 etching apparatus

110 processing container

111 placing part

130 st beta-diketone supplier

131. 132, 133, 134, 135, 136 piping

137 (1) beta-diketone container

140 nd 2 beta-diketone supplier

141. 142 piping

150 additive gas supply unit

151. 152 piping

160 inert gas supply part

161. 162 piping

170 reducing gas supply unit

171. 172 piping

180 heating device

181. 182 piping

183 vacuum pump

184 liquid nitrogen collector

MFC1, MFC2, MFC3, MFC4, MFC5 flow control device

PI1, PI2 pressure gauge

V1、V2、V3、V4、V5、V6、V7、V8、V9、V10、V11、V12、V13、

V14 and V15 valves.