JP2004212563A - Formation method of resist pattern and manufacture method of semiconductor device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a formation method of resist pattern which suppresses the decrease of concentrations of an acid generator or an acid generated from the acid generator in a resist film and is capable of forming a resist pattern having a rectangular shape, and to provide a manufacture method of a semiconductor device using the formation method. <P>SOLUTION: In the formation method of resist pattern, the chemically amplified resist film 4 comprising a silicon dioxide film 2, an antireflection film 3 and the acid generator is formed on a semiconductor substrate 1. The resist film 4 is irradiated with exposure light via a prescribed mask, thereby, the acid is generated from the acid generator on an exposure part and, thereafter, the resist film 4 is heat-treated in a heating atmosphere containing the acid generator or acid materials. Thereafter, the resist film 4 is subjected to development and the resist pattern is formed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a resist pattern of a chemically amplified resist and a method for manufacturing a semiconductor device using the same, and more particularly, to a KrF excimer laser beam, an ArF excimer laser beam, or a FrF excimer laser beam. ₂ The present invention relates to a method of forming a resist pattern of a chemically amplified resist corresponding to an exposure apparatus using excimer laser light as a light source, and a method of manufacturing a semiconductor device using the same.
[0002]
[Prior art]
In recent years, as the degree of integration of semiconductor devices has increased, the dimensions of individual elements have been miniaturized, and the widths of wirings, gates, etc. constituting each element have also been miniaturized.
[0003]
The photolithography technology that supports this miniaturization includes a process of applying a resist composition to the surface of a substrate to be processed to form a resist film, and irradiating light to expose a predetermined resist pattern to form a resist pattern latent image. Forming, a heat treatment if necessary, a step of developing this to form a desired fine pattern, and a step of performing processing such as etching on the substrate to be processed using the fine pattern as a mask. included.
[0004]
As one of means for miniaturizing a pattern, shortening the wavelength of exposure light used for forming the resist pattern latent image has been promoted.
[0005]
Conventionally, for manufacturing a DRAM having a degree of integration of, for example, 64 Mbits, an i-line (wavelength: 365 nm) of a high-pressure mercury lamp has been used as a light source. In recent years, a technology using a KrF (krypton fluoride) excimer laser (wavelength: 248 nm) as an exposure light source has been put to practical use in a mass production process of a 256 megabit DRAM. For the manufacture of a DRAM having a degree of integration of 1 gigabit or more, practical use of an ArF (argon fluoride) excimer laser (wavelength: 193 nm) is being studied. Further, as a technique for realizing a fine pattern corresponding to a design rule of 100 nm or less, F has a shorter wavelength. ₂ It is also considered to use a (fluorine) excimer laser (wavelength: 157 nm) as an exposure light source.
[0006]
On the other hand, electron beam lithography technology is being developed as a higher resolution exposure technology. Since the electron beam lithography technology has an inherently excellent resolution, it has been applied to the development of leading-edge devices typified by DRAMs, and is also partially used in the production of ASICs.
[0007]
In such photolithography technology and electron beam lithography technology, a chemically amplified resist has conventionally been used.
[0008]
Generally, a positive chemically amplified resist contains an alkali-insoluble polymer and an acid generator. Here, the alkali-insoluble polymer has, for example, a structure in which a phenolic hydroxyl group of polyvinyl phenol is blocked by a protecting group.
[0009]
When such chemically amplified resist is irradiated with exposure light through an appropriate mask, an acid is generated by the decomposition of the acid generator at the exposed portion. After that, when a heat treatment is performed, the protective group blocking the phenolic hydroxyl group is thermally decomposed by the catalytic action of the acid, so that the protective group is removed to become a phenolic hydroxyl group. Thereby, the chemically amplified resist becomes alkali-soluble in the exposed portion. Therefore, a desired resist pattern can be formed by dissolving and removing the exposed portion by a developing process using an alkali developing solution.
[0010]
[Problems to be solved by the invention]
However, in the heat treatment step after the exposure, there is a problem that the acid generator and the acid generated from the acid generator evaporate, so that they are diffused outside the resist. Since such a phenomenon is particularly observed near the surface of the resist, there has been a problem that an alkali-soluble structure is not formed near the surface of the resist due to the remaining protective group due to a decrease in the acid concentration.
[0011]
When such a resist is alkali-developed, the upper part of the resist is more difficult to dissolve in the developing solution than the lower part of the resist, so that the resist shape is not an ideal rectangular shape but an inverted taper shape (T-top shape). It becomes. Therefore, there has been a problem that the controllability of the resist dimensions is significantly reduced. Also, when processing the base film using the obtained resist pattern as a mask, there is a problem that it cannot be processed into a pattern having desired dimensions and shape.
[0012]
Such a problem is found not only in the above-mentioned positive resist but also in a negative resist. The negative resist has a structure that is hardly dissolved in the developing solution by hardening the exposed portion. However, due to the evaporation of the acid generator and the acid generated from the acid generator in the heat treatment step, the resist upper portion is more easily dissolved in the developer than the resist lower portion. For this reason, there has been a problem that the resist shape after the development becomes an inversely tapered shape and a remarkable film reduction occurs.
[0013]
Further, the effect of the evaporation of the acid from the resist surface becomes more remarkable as the ratio of the surface area to the resist film thickness increases. ArF excimer laser or F ₂ In an exposure technique using a light source such as an excimer laser, a resist having a small film thickness is required.
[0014]
The present invention has been made in view of such a problem. That is, an object of the present invention is to provide a resist pattern forming method capable of suppressing a decrease in the concentration of an acid generator or an acid generated from an acid generator in a resist film and forming a resist pattern having a rectangular shape. And a method of manufacturing a semiconductor device using the same.
[0015]
Another object of the present invention is to suppress the evaporation of an acid generator or an acid generated from an acid generator regardless of the thickness of a resist film. ₂ An object of the present invention is to provide a resist pattern forming method capable of forming a good pattern even with a resist corresponding to an exposure apparatus using an excimer laser or the like as a light source, and a method of manufacturing a semiconductor device using the same.
[0016]
Other objects and advantages of the present invention will become apparent from the following description.
[0017]
[Means for Solving the Problems]
The present invention provides a first step of forming a chemically amplified resist film containing an acid generator on a substrate to be processed, and irradiating the resist film with exposure light through a predetermined mask to form an exposure portion. A second step of generating an acid from the acid generator by a third step; and a third step of subjecting the processed substrate after the second step to a heating atmosphere containing the acid generator and performing a heat treatment on the resist film. And a fourth step of performing development processing on the resist film.
[0018]
The third step can be performed in a state where a gas-liquid equilibrium is established between the acid generator in the heating atmosphere or the acid generated from the acid generator and the acid generator or the acid in the resist film.
[0019]
The acid generator in the resist film can be a photoacid generator or an electron beam acid generator.
[0020]
The acid generator added to the heating atmosphere can be a photoacid generator or a thermal acid generator.
[0021]
The acid generator in the resist film and the acid generator added in the heating atmosphere can be the same substance.
[0022]
Further, the present invention provides a first step of forming a chemically amplified resist film containing an acid generator on a substrate to be processed, and irradiating the resist film with exposure light through a predetermined mask, A second step of generating an acid from the acid generator in the exposed portion, and a third step of subjecting the processed substrate after the second step to a heating atmosphere containing an acid and performing a heat treatment on the resist film. And a fourth step of performing development processing on the resist film.
[0023]
The third step can be performed in a state where a gas-liquid equilibrium is established between the acid in the heating atmosphere and the acid in the resist film.
[0024]
In the present invention, the third step can be performed using a closed heating furnace.
[0025]
In the present invention, the thickness of the resist film can be in the range of 50 nm to 400 nm.
[0026]
In the present invention, the exposure light may be KrF excimer laser light having a wavelength of 248 nm.
[0027]
In the present invention, the exposure light may be ArF excimer laser light having a wavelength of 193 nm.
[0028]
Further, in the present invention, the exposure light has a wavelength of 157 nm. ₂ Excimer laser light can be used.
[0029]
Furthermore, the present invention relates to a method for manufacturing a semiconductor device using the above-described method for forming a resist pattern using a substrate to be processed as a semiconductor substrate.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
A method for forming a resist pattern according to the present embodiment and a method for manufacturing a semiconductor device using the same will be described with reference to FIGS.
[0031]
First, a semiconductor substrate is prepared as a substrate to be processed. For example, as shown in FIG. 1, silicon dioxide (SiO 2) ₂ 2) Form the film 2.
[0032]
As the semiconductor substrate, for example, a silicon substrate can be used. An element isolation region, a diffusion layer serving as a source or a drain, or the like may be formed in the semiconductor substrate.
[0033]
The silicon dioxide film can be formed by, for example, a chemical vapor deposition method (hereinafter, referred to as CVD).
[0034]
The film formed on the semiconductor substrate is not limited to a silicon dioxide film. Other films may be formed as long as they are used in a semiconductor device manufacturing process and require patterning. For example, silicon nitride (Si ₃ N ₄ A) Another insulating film such as a film may be formed, or a conductive film may be formed. Further, the film formed on the semiconductor substrate is not limited to a single-layer film, and may be a film in which two or more films are stacked. Further, these films may be formed on a semiconductor substrate on which a gate electrode and the like are formed.
[0035]
Next, as shown in FIG. 2, an antireflection film 3 is formed on the silicon dioxide film 2.
[0036]
The antireflection film 3 has a role of eliminating the reflection of the exposure light at the interface between the resist film and the antireflection film by absorbing the exposure light transmitted through the resist film when patterning the resist film formed in a later step. Fulfill. As the antireflection film, a film containing an organic substance as a main component can be used, and for example, can be formed by a spin coating method or the like. In the present invention, the anti-reflection film may not be provided.
[0037]
Next, as shown in FIG. 3, a chemically amplified resist film 4 is formed on the antireflection film 3. The thickness of the resist film can be a predetermined thickness according to the manufacturing process of the semiconductor device. For example, KrF excimer laser, ArF excimer laser or F ₂ In order to correspond to an exposure apparatus using an excimer laser as a light source, the thickness may be in the range of 50 nm to 400 nm.
[0038]
As the chemically amplified resist, for example, a resist containing an alkali-insoluble polymer and an acid generator can be used. As the alkali-insoluble polymer, for example, a polymer obtained by protecting an alkali-soluble functional group such as a hydroxyl group with a protecting group such as a t-butoxycarbonyl group can be used.
[0039]
As the acid generator, a photoacid generator that generates an acid by light, an electron beam acid generator that generates an acid by an electron beam, and the like can be used. Examples of the photoacid generator include triphenylsulfonium triflate.
[0040]
The chemically amplified resist to which the present invention can be applied is not limited to a two-component resist composed of an alkali-insoluble polymer and an acid generator. The present invention can be applied to a three-component resist composed of, for example, an alkali-soluble polymer, an acid generator and a dissolution inhibitor.
[0041]
Next, as shown in FIG. 4, the resist film 4 is irradiated with exposure light 6 via a predetermined mask 5. Examples of the exposure apparatus include an ultraviolet exposure apparatus, an electron beam exposure apparatus, a KrF excimer exposure apparatus, an ArF excimer exposure apparatus, and an F exposure apparatus. ₂ An excimer exposure apparatus or the like can be used.
[0042]
This exposure is performed for the purpose of forming a predetermined resist pattern latent image on the resist film 4. That is, by irradiating the resist film 4 with exposure light, a resist pattern latent image including an exposed portion 41 and an unexposed portion 42 is formed in the resist film 4 as shown in FIG. At this time, in the exposed part 41, an acid is generated from the acid generator contained in the resist film. On the other hand, in the unexposed portion 42, the acid generator is not exposed, so that no acid is generated.
[0043]
Next, a heat treatment is performed on the exposed semiconductor substrate. In the present invention, the heat treatment is preferably performed in a closed heating furnace.
[0044]
According to the present invention, an acid generator is added to an atmosphere, and a gas-liquid equilibrium is established between a gaseous acid generator or an acid generated therefrom in a heating atmosphere and an acid generator or an acid present in a resist film. It is characterized in that the heat treatment is performed in a state where is satisfied. The acid generator added to the atmosphere may be a substance that generates an acid by heat or a substance that generates an acid by light. For example, the same substance as the acid generator contained in the resist film can be used.
[0045]
Further, in the present invention, an acid may be added to the atmosphere, and the heat treatment may be performed in a state where a gas-liquid equilibrium is established between the acid and the acid present in the resist film.
[0046]
When a semiconductor substrate is placed in a heating furnace and heat treatment is performed, when the temperature rises and reaches the boiling point of the acid generator in the resist film, the acid generator evaporates and moves from the resist film into the atmosphere. And spread. However, the atmosphere is previously filled with the vapor of the acid generator so that, at a predetermined heating temperature, a gas-liquid equilibrium is established between the acid generator present in the resist film and the acid generator present in the atmosphere. By doing so, it is possible to prevent the evaporation of the acid generator from the resist film from being apparently performed.
[0047]
Further, even when the vapor of the acid generated from the acid generator added to the atmosphere and the acid present in the resist film are in a gas-liquid equilibrium state, even if the acid in the resist film in the heat treatment step is in a vapor-liquid equilibrium state, Evaporation can be apparently suppressed.
[0048]
Furthermore, by adding an acid to the atmosphere so that the acid and the acid present in the resist film are in a gas-liquid equilibrium state, the evaporation of the acid from the resist film in the heat treatment step may be apparent. It can be suppressed.
[0049]
The amount of the acid generator to be added to the atmosphere is such that, at a predetermined heating temperature, a gas-liquid equilibrium can be established between the acid generator or the acid in the resist film and the acid generator or the acid in the atmosphere. Amount. Similarly, the amount of the acid to be added to the atmosphere is set to an amount capable of establishing a gas-liquid equilibrium between the acid in the resist film and the acid in the atmosphere at a predetermined heating temperature. When the heat treatment temperature increases, the amount of the acid generator and the acid evaporated from the resist film increases, so that the amount of the acid generator or the acid added to the atmosphere also needs to be increased.
[0050]
According to the present invention, an acid generator or an acid is added to the atmosphere, and the heat treatment of the semiconductor substrate is performed in a state where the heating atmosphere is filled with the acid generator or the vapor of the acid generated from the acid generator or the vapor of the added acid. This makes it possible to suppress the evaporation of the acid generator or acid from the resist film. As a result, the concentration of the acid in the exposed portion can be made uniform, and as shown in FIG. 5, the thermal decomposition reaction of the protecting group proceeds to uniformly form the structure of the alkali-soluble polymer in the entire exposed portion 41 '. Can occur.
[0051]
The present invention is particularly effective when the thickness of the resist film is small (for example, when the thickness is 50 nm to 400 nm). When the thickness of the resist film is small, the concentration of the acid generator or the acid existing in the resist film is significantly reduced due to the evaporation of the acid generator or the acid from the resist film. According to the present invention, a resist film in an exposed portion can be uniformly made to have an alkali-soluble structure by suppressing evaporation of an acid generator or an acid, so that a good resist pattern can be formed regardless of the thickness of the resist film. Becomes possible. Therefore, KrF excimer laser, ArF excimer laser or F ₂ A good pattern can be formed even with a resist corresponding to an exposure apparatus using an excimer laser as a light source.
[0052]
After the completion of the heat treatment step, development is performed under ordinary conditions. The development can be performed, for example, by alkali development using an aqueous solution of tetramethylammonium hydroxide.
[0053]
In the resist film, an alkali-soluble polymer is generated in an exposed portion, while an alkali-insoluble polymer remains in an unexposed portion. Therefore, by performing the developing process, only the exposed portion is dissolved and removed in the developing solution, and as a result, a rectangular resist pattern 7 as shown in FIG. 6 is formed.
[0054]
For comparison, FIG. 7 shows a conventional method of forming a resist pattern. FIG. 7A is a schematic diagram of a resist film after a heat treatment according to a conventional method, and FIG. 7B is a schematic diagram of a resist pattern after a development process of FIG. 7A.
[0055]
In the exposure step, the exposure light is irradiated through a predetermined mask, so that the acid generated from the acid generator is present in the exposed portion. On the other hand, no acid is present in the unexposed portions. Next, when a drying treatment is performed in a dry atmosphere, the acid generated in the exposed portion evaporates from the surface of the resist film, and as a result, the upper portion of the resist film has a lower acid concentration than the lower portion. Therefore, as shown in FIG. 7A, the resist film 8 is roughly divided into three regions having different acid concentrations, an exposed portion upper portion 81, an exposed portion lower portion 82, and an unexposed portion 83.
[0056]
Since the difference in acid concentration causes a difference in the alkali solubilization reaction of the polymer, the resist pattern becomes a pattern having a shape as shown in FIG. That is, the resist film in the unexposed portion 83 remains undissolved in the developer because it is insoluble in alkali. On the other hand, the resist film in the exposed portion lower portion 82 is removed by dissolving in a developing solution because it is soluble in alkali. However, since the resist film in the exposed portion upper portion 81 has a non-uniform alkali-soluble structure due to lack of acid, it becomes more difficult to dissolve in the developer toward the upper portion. Therefore, in the upper portion 81 of the exposed portion, the shape after the development processing is a tapered shape.
[0057]
On the other hand, according to the present embodiment, since the resist film in the exposed portion has a uniform alkali-soluble structure, the resist film in the exposed portion can be removed in a rectangular shape by the developing treatment. Thereby, the shape of the resist pattern formed by the remaining unexposed resist film can also be made rectangular.
[0058]
After a resist pattern is formed according to the method described in this embodiment, the silicon dioxide film can be processed into a desired pattern by etching the underlying silicon dioxide film using the resist pattern as a mask. In addition, by applying the etching process using the resist pattern as a mask to a method for manufacturing a semiconductor device, a semiconductor device having good element characteristics can be manufactured.
[0059]
In this embodiment mode, an example using a positive resist has been described. However, the present invention is not limited to this, and can be applied to a negative resist.
[0060]
Further, in this embodiment, an example in which a resist pattern is formed on a semiconductor base material has been described, but the present invention is not limited to this. The present invention can be applied to other uses as long as the purpose requires patterning of a base material using a resist pattern as a mask. For example, the base material may be a thin film formed on a glass substrate, or may be a thin film formed on a plastic substrate.
[0061]
According to the present embodiment, by performing the heat treatment in a state in which the acid generator or the acid is added to the heating atmosphere, the evaporation of the acid generator or the acid from the resist film can be suppressed. Therefore, the resist film in the exposed portion can be changed to a uniform alkali-soluble structure over and under the exposed portion, so that the shape of the resist pattern after the development processing can be rectangular.
[0062]
Further, according to the present embodiment, since the evaporation of the acid can be suppressed regardless of the thickness of the resist film, the KrF excimer laser, the ArF excimer laser or the Fr excimer laser can be used. ₂ A good pattern can be formed even with a resist having a film thickness in the range of 50 nm to 400 nm, which is formed corresponding to an exposure apparatus using an excimer laser or the like as a light source.
[0063]
Furthermore, according to the present embodiment, since a resist pattern having a rectangular shape can be formed, it is possible to process the base film into a pattern having desired dimensions and shapes.
[0064]
【Example】
Embodiment 1 FIG.
First, a silicon dioxide film was formed with a thickness of about 500 nm on a silicon substrate by a CVD method.
[0065]
Next, AR19 manufactured by Shipley was formed as an anti-reflection film on the silicon dioxide film. Specifically, the solution of AR19 was spin-coated on the silicon dioxide film by a spin coater, and then heat-treated at 215 ° C. for 90 seconds. The thickness of the obtained AR19 was about 85 nm.
[0066]
Subsequently, an ArF resist PAR-700 manufactured by Sumitomo Chemical Co., Ltd. was formed as a resist film on the antireflection film. Specifically, after the PAR-700 solution was spin-coated on the antireflection film by a spin coater, a heat treatment was performed at 110 ° C. for 60 seconds. The thickness of the obtained PAR-700 was about 300 nm.
[0067]
Next, using an exposure machine ArF excimer scanner S302A manufactured by Nikon Corporation, a resist film having a line and space pattern (line width 130 nm, space width 130 nm) was 7.0 mJ / cm through a mask having a line and space pattern. ² Of exposure light. The numerical aperture (NA) of the exposure machine was 0.60, and σ (NA of light source / NA of lens) was 0.70.
[0068]
Next, the exposed silicon substrate was placed in a proximity-type closed oven and heat-treated at 115 ° C. for 60 seconds. The atmosphere in the oven was obtained by adding triphenylsulfonium triflate to dry air at a concentration of about 100 ppm.
[0069]
Next, the semiconductor substrate after the heat treatment was immersed in a 2.38% aqueous solution of tetramethylammonium hydroxide for 60 seconds, and then rinsed with pure water for 60 seconds.
[0070]
Observation of the obtained resist pattern revealed that a good rectangular pattern was formed.
[0071]
Embodiment 2. FIG.
First, a silicon dioxide film was formed with a thickness of about 500 nm on a silicon substrate by a CVD method.
[0072]
Next, DUV30J manufactured by Brewer Science was formed as an anti-reflection film on the silicon dioxide film. Specifically, after a solution of DUV30J was spin-coated on the silicon dioxide film by a spin coater, a heat treatment was performed at 205 ° C. for 90 seconds. The thickness of the obtained DUV30J was about 85 nm.
[0073]
Then, on the anti-reflection film, Clariant F ₂ The resist FX-1000P was formed as a resist film. Specifically, the FX-1000P solution was spin-coated on the antireflection film by a spin coater, and then heat-treated at 150 ° C. for 60 seconds. The film thickness of the obtained FX-1000P was about 120 nm.
[0074]
Next, an exposing machine F ₂ Using a microstepper, a resist film having a thickness of 20 mJ / cm was passed through a mask having a line and space pattern (line width 70 nm, space width 70 nm). ² Of exposure light. The numerical aperture (NA) of the exposure machine was 0.85, and σ (NA of light source / NA of lens) was 0.70.
[0075]
Next, the exposed silicon substrate was placed in a proximity-type closed oven and heat-treated at 130 ° C. for 90 seconds. The atmosphere in the oven was obtained by adding triphenylsulfonium triflate to dry air at a concentration of about 100 ppm.
[0076]
Next, the semiconductor substrate after the heat treatment was immersed in a 2.38% aqueous solution of tetramethylammonium hydroxide for 30 seconds, and then rinsed with pure water for 60 seconds.
[0077]
Observation of the obtained resist pattern revealed that a good rectangular pattern was formed.
[0078]
Comparative Example 1
First, a silicon dioxide film was formed with a thickness of about 500 nm on a silicon substrate by a CVD method.
[0079]
Next, AR19 manufactured by Shipley was formed as an anti-reflection film on the silicon dioxide film. Specifically, the solution of AR19 was spin-coated on the silicon dioxide film by a spin coater, and then heat-treated at 215 ° C. for 90 seconds. The thickness of the obtained AR19 was about 85 nm.
[0080]
Subsequently, an ArF resist PAR-700 manufactured by Sumitomo Chemical Co., Ltd. was formed as a resist film on the antireflection film. Specifically, after the PAR-700 solution was spin-coated on the antireflection film by a spin coater, a heat treatment was performed at 110 ° C. for 60 seconds. The thickness of the obtained PAR-700 was about 300 nm.
[0081]
Next, using an exposure machine ArF excimer scanner S302A manufactured by Nikon Corporation, a resist film having a line and space pattern (line width 130 nm, space width 130 nm) was 7.0 mJ / cm through a mask having a line and space pattern. ² Of exposure light. The numerical aperture (NA) of the exposure machine was 0.60, and σ (NA of light source / NA of lens) was 0.70.
[0082]
Next, the exposed silicon substrate was placed in a proximity-type closed oven and heat-treated at 115 ° C. for 60 seconds. The oven had a dry air atmosphere.
[0083]
Next, the semiconductor substrate after the heat treatment was immersed in a 2.38% aqueous solution of tetramethylammonium hydroxide for 60 seconds, and then rinsed with pure water for 60 seconds.
[0084]
Observation of the obtained resist pattern revealed that the shape of the resist pattern above the exposed portion was tapered.
[0085]
Comparative Example 2.
First, a silicon dioxide film was formed with a thickness of about 500 nm on a silicon substrate by a CVD method.
[0086]
Next, DUV30J manufactured by Brewer Science was formed as an antireflection film on the silicon dioxide film. Specifically, after a solution of DUV30J was spin-coated on the silicon dioxide film by a spin coater, a heat treatment was performed at 205 ° C. for 90 seconds. The thickness of the obtained DUV30J was about 85 nm.
[0087]
Subsequently, on the anti-reflection film, Clariant F ₂ The resist FX-1000P was formed as a resist film. Specifically, the FX-1000P solution was spin-coated on the antireflection film by a spin coater, and then heat-treated at 150 ° C. for 60 seconds. The film thickness of the obtained FX-1000P was about 120 nm.
[0088]
Next, the exposing machine F ₂ Using a microstepper, a resist film having a thickness of 20 mJ / cm was passed through a mask having a line and space pattern (line width 70 nm, space width 70 nm). ² Of exposure light. The numerical aperture (NA) of the exposure machine was 0.85, and σ (NA of light source / NA of lens) was 0.70.
[0089]
Next, the exposed silicon substrate was placed in a proximity-type closed oven and heat-treated at 130 ° C. for 90 seconds. The oven had a dry air atmosphere.
[0090]
Next, the semiconductor substrate after the heat treatment was immersed in a 2.38% aqueous solution of tetramethylammonium hydroxide for 30 seconds, and then rinsed with pure water for 60 seconds.
[0091]
Observation of the obtained resist pattern revealed that the shape of the resist pattern above the exposed portion was tapered.
[0092]
【The invention's effect】
According to the present invention, by performing the heat treatment in a state where the acid generator or the acid is added to the heating atmosphere, the evaporation of the acid generator or the acid from the resist film can be suppressed. Therefore, the resist film in the exposed portion can be changed to a uniform alkali-soluble structure over and under the exposed portion, so that the shape of the resist pattern after the development processing can be made rectangular.
[0093]
Further, according to the present invention, the evaporation of the acid can be suppressed irrespective of the thickness of the resist film, so that a good pattern can be formed even with a thin resist film. Therefore, KrF excimer laser, ArF excimer laser or F ₂ It is possible to form a resist pattern having a good shape corresponding to an exposure apparatus using an excimer laser or the like as a light source.
[0094]
Furthermore, according to the present invention, since a resist pattern having a rectangular shape can be formed, a semiconductor device having good element characteristics can be manufactured by processing a base film into a desired pattern.
[Brief description of the drawings]
FIG. 1 is a view showing an example of a method for forming a resist pattern according to the present invention.
FIG. 2 is a diagram showing an example of a method for forming a resist pattern according to the present invention.
FIG. 3 is a diagram showing an example of a method for forming a resist pattern according to the present invention.
FIG. 4 is a diagram showing an example of a method for forming a resist pattern according to the present invention.
FIG. 5 is a diagram showing an example of a method for forming a resist pattern according to the present invention.
FIG. 6 is a diagram illustrating an example of a method for forming a resist pattern according to the present invention.
7A and 7B are diagrams showing a conventional resist pattern forming method, in which FIG. 7A is a schematic diagram of a resist film after a heat treatment by a conventional method, and FIG. FIG.
[Explanation of symbols]
1 semiconductor substrate, 2 silicon dioxide film, 3 anti-reflection film, 4 resist film, 5 mask, 6 exposure light, 7,8 resist pattern.

Claims (13)

A first step of forming a chemically amplified resist film containing an acid generator on a substrate to be processed;
A second step of irradiating the resist film with exposure light through a predetermined mask to generate an acid from the acid generator in an exposed portion;
A third step of placing the substrate after the second step in a heating atmosphere containing an acid generator and subjecting the resist film to a heat treatment;
And a fourth step of performing a development process on the resist film. The third step is a state in which a gas-liquid equilibrium is established between the acid generator or the acid generated from the acid generator in the heating atmosphere and the acid generator or the acid in the resist film. 2. The method for forming a resist pattern according to claim 1, wherein the method is performed. The method according to claim 1, wherein the acid generator in the resist film is a photoacid generator or an electron beam acid generator. The method according to claim 1, wherein the acid generator added to the heating atmosphere is a photo acid generator or a thermal acid generator. The method according to any one of claims 1 to 4, wherein the acid generator in the resist film and the acid generator added in the heating atmosphere are the same substance. A first step of forming a chemically amplified resist film containing an acid generator on a substrate to be processed;
A second step of irradiating the resist film with exposure light through a predetermined mask to generate an acid from the acid generator in an exposed portion;
A third step of placing the substrate after the second step in a heating atmosphere to which an acid has been added and performing a heat treatment on the resist film;
And a fourth step of performing a development process on the resist film. 7. The method according to claim 6, wherein the third step is performed in a state where a gas-liquid equilibrium is established between the acid in the heating atmosphere and the acid in the resist film. The resist pattern forming method according to any one of claims 1 to 7, wherein the third step is performed using a closed heating furnace. The method according to claim 1, wherein the resist film has a thickness of 50 nm to 400 nm. The resist pattern forming method according to claim 1, wherein the exposure light is a KrF excimer laser light having a wavelength of 248 nm. The resist pattern forming method according to any one of claims 1 to 9, wherein the exposure light is ArF excimer laser light having a wavelength of 193 nm. A resist pattern forming method according to any one of claims 1 to 9 wherein the exposure light is F ₂ excimer laser beam having a wavelength of 157 nm. The method for manufacturing a semiconductor device using the method for forming a resist pattern according to claim 1, wherein the substrate to be processed is a semiconductor substrate.

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