JPH06110214A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To provide the method for formation of resist patterns capable of forming positive type or negative resist patterns in such a manner that eaves are not formed in the upper part of the positive resist patterns as well as rounding parts are not formed in the negative resist patterns even at the time of finely forming these patterns, of stably forming the resist patterns to the line widths of desired widths and of stably forming the patterns after etching to the line widths of desired sizes. CONSTITUTION:This method is so constituted as to include a stage for applying a chemical amplification resist 2 onto a substrate 1, a stage for forming a transparent film 3 contg. a photo-acid generator on the chemical amplification resist 2, a stage for pattern exposuring the chemical amplification resist 2 a stage for removing this transparent film 3, a stage for subjecting the chemical amplification resist 2 to pattern exposing and a stage for forming the chemical amplification resist patterns 2a by developing the chemical amplification resist 2 subjected to the pattern exposing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resist pattern, and more particularly, it can be applied to a photolithography technique in a method for manufacturing a semiconductor integrated circuit. The present invention relates to a method for forming a resist pattern, which can stably form a resist pattern line width with a desired dimension when forming the resist pattern.

In recent years, LSIs are required to have a high degree of integration, and with the demand for the high degree of integration, miniaturization of circuit patterns is required. For this reason, the resolution and the wavelength of the exposure apparatus are becoming higher, and the resist is also required to have a higher resolution. As for the resist, recently, a chemically amplified resist containing a photo-acid generator is in the spotlight because it has a higher sensitivity than a resist such as a normal novolac resin, and is actively developed.

[0003]

2. Description of the Related Art A conventional method for forming a chemically amplified resist pattern will be described. First, a chemically amplified resist film is formed by spin coating, the formed chemically amplified resist film is subjected to a first heat treatment (Prebake), and then pattern exposure is performed via a reticle. At this time, acid is generated only in the chemically amplified resist portion which has been subjected to pattern exposure and irradiated with the ionizing irradiation line. When the ionizing irradiation beam is a charged particle such as an electron beam, the chemically amplified resist film is normally scanned without passing through the reticle. Then, after the pattern exposure, a second heat treatment (PEB) is performed. At this time, the acid generated in the positive resist solubilizes the base resin. Then, the solubilized portion of the chemically amplified resist film is removed by development to form a chemically amplified resist pattern. At this time, since the generated acid serves as a catalyst to solubilize many base resins, the resist pattern can be formed with higher sensitivity than a normal resist pattern.

[0004]

However, in this resist pattern forming method, in the case of a positive resist, the vicinity of the resist surface is affected by the impurities in the atmosphere despite the region irradiated with the ionizing irradiation line. When it becomes insoluble, the cross-sectional shape may cause problems such that the vicinity of the surface overhangs like eaves, or pattern formation cannot be performed at all. Specifically, as shown in FIG. 2A, a positive type chemically amplified resist 32 is applied on a substrate 31,
When exposed as shown in FIG. 2B, the exposed resist
At the same time when acid (H ⁺ ) is generated in the 32 region, the acid on the exposed resist 32 region surface starts to be consumed due to the influence of impurities such as amine contained in the processing atmosphere.
2B, the acid on the surface is further consumed, and when the resist is developed with an alkali developing solution as shown in FIG. 2D, the upper portion of the resist 32 from which the acid has been removed becomes difficult to dissolve in the alkali developing solution. There was a phenomenon that an eaves was generated on the upper part of the resist pattern 32a. Since the eaves generated on the upper part of the resist pattern 32a are formed larger than the dimension of the bottom part of the pattern 32a, when the underlayer is dry-etched using the pattern 32a in which the eaves are formed as a mask, the pattern line of the underlayer after etching is formed. The width was narrower than desired. Moreover, the eaves are not formed in a uniform shape with good reproducibility, but are easily varied due to the influence of the atmosphere, so that the line width of the pattern 32a becomes unstable, and as a result, the eaves of the base after etching is finished. The pattern line width was also unstable. When the pattern is further miniaturized, as shown in FIG. 2 (e), the pattern is not developed, and the upper portion of the resist pattern 32a is connected, which sometimes makes it impossible to function as a mask.

Further, in the case of a negative chemically amplified resist,
Contrary to the case of the positive type chemically amplified resist, there was a problem that the vicinity of the surface of the exposed portion was solubilized due to the influence of impurities in the atmosphere and the top shape was rounded. Therefore, in order to solve the above problem, it is considered that the resist surface and the impurity atmosphere are blocked and a transparent film is applied on the resist before exposure, but this method also reduces the degree, but Such a problem may occur.

As described above, the conventional method of forming a resist pattern has problems that a fine pattern is not resolved and that the resist pattern line width and the pattern line width after etching become unstable. Therefore, the present invention can prevent eaves from being formed on the positive resist pattern when finely forming the positive or negative resist pattern, and can prevent the negative resist pattern from being rounded. A resist pattern forming method capable of stably forming a resist pattern line width with a desired dimension and stably forming a pattern line width after etching with a desired dimension is provided. I am trying.

[0007]

In order to achieve the above object, the method for forming a resist pattern according to the present invention comprises a step of applying a chemically amplified resist on a substrate, and then containing a photo-acid generator on the chemically amplified resist. Forming a transparent film, then performing a pattern exposure of the chemically amplified resist, then removing the transparent film, and then developing the chemically exposed resist that has undergone pattern exposure to obtain a chemically amplified resist. And a step of forming a pattern.

In order to achieve the above object, the method for forming a resist pattern according to the present invention comprises a step of applying a chemically amplified resist on a substrate, and then forming a transparent film containing a photo-acid generator on the chemically amplified resist. A step of pattern exposing the chemically amplified resist, and
Developing the pattern-exposed chemically amplified resist to form a chemically amplified resist pattern, and removing the transparent film.

In the present invention, heat treatment is performed between the resist coating step and the transparent film forming step, or heat treatment is performed between the transparent film forming step and the pattern exposing step, or both of them. (Claims 1 and 2), or when heat treatment is performed between the transparent film removing step and the developing step (Claim 1), The heat treatment may be performed between the pattern exposing step and the transparent film removing step (claims 1 and 2).

In the present invention, the photoacid generator contained in the transparent film is not particularly limited, but the same material as the photoacid generator contained in the chemically amplified resist of the lower layer or the photoacid generator of the lower layer is used. It is desirable that it generate the same acid as the photo-acid generator contained in the chemically amplified resist.
In the present invention, ionizing radiation is preferably used for pattern exposure, and examples of the ionizing radiation include electromagnetic waves such as visible light, ultraviolet rays and X-rays, and particle beams such as electron beams and ion beams.

[0011]

As described above, conventionally, the acid on the surface is consumed and eaves (positive type) and roundness (negative type) are generated on the upper portion of the resist pattern. On the other hand, in the present invention, FIG.
As shown in (a), for example, a positive chemically amplified resist 2 is applied on the substrate 1, and then a transparent film 3 containing a photo-acid generator is formed on the chemically amplified resist 2, and then, as shown in FIG.
As shown in (b), after performing pattern exposure and PEB with the chemically amplified resist 2 protected by the transparent film 3, the transparent film 3 is removed (PEB may be before removal of the transparent film 3), and FIG. As shown in c), the chemically amplified resist 2 is developed to form the chemically amplified resist pattern 2a. The transparent film 3 may be removed at the same time as the development, not after the pattern exposure.

As described above, since the pattern exposure and PEB are performed while the chemically amplified resist 2 is protected by the transparent film 3 containing the photo-acid generator, the pattern is exposed with the conventional positive chemically amplified resist exposed. Exposure and PEB
The surface of the chemically amplified resist 2 can be prevented from being exposed to the treatment atmosphere, and the influence of impurities such as amine contained in the treatment atmosphere can be lessened than in the case of performing the above. The consumption of acid on the surface of the region can be suppressed. Therefore, the resist pattern 2
It is possible to prevent the eaves from being formed on the upper part of a, and it is possible to stably form the resist pattern 2a having a desired line width.

Further, even if impurities such as amine in the processing atmosphere invade or diffuse into the upper portion of the resist 2 when the lower layer positive chemically amplified resist 2 is applied, the acid is consumed even if the acid generated after exposure is consumed. Since the upper part of the resist 2 is covered with the transparent film 3 containing the photo-acid generator, the acid generated in the transparent film can be diffused to the upper part of the resist 2 to be supplemented. Therefore, the consumption of acid on the upper portion of the resist 2 can be suppressed more than in the case of the conventional transparent film containing no photo-acid generator, so that the resist pattern 2 having an excellent shape can be obtained.

Although the positive type has been described as an example, the negative type can suppress the consumption of the acid on the surface of the chemically amplified resist as in the case of the positive type, so that the upper portion of the resist pattern is not rounded. Therefore, the resist pattern line width can be stably formed in a desired dimension.

[0015]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. First, each comparative example will be described. (Comparative Example 1) A compound in which 40% of hydroxyl groups of polyvinylphenol were t-butoxycarponoxylated on a silicon substrate, and triphenylsulfonium triflate (a p-toluenesulfonic acid phenyl ester or the like may be used) as a photoacid generator. Positive chemically amplified resist composed of ethyl lactate is applied to a thickness of about 0.7 μm, and 1
Baking was performed at 10 ° C. for 90 seconds, and then pattern exposure was performed with a laser beam having a wavelength of 248 nm. Immediately after pattern exposure, heat treatment on a hot plate at 90 ° C / 90 seconds,
Paddle development was performed for 60 seconds with a 2.38% TMAH aqueous solution. Observation of the cross-sectional shape revealed that a surface-insoluble layer was remarkably generated. (Comparative Example 2) A compound in which 40% of hydroxyl groups of polyvinylphenol are t-butoxycarponoxylated on a silicon substrate, and triphenylsulfonium triflate (a p-toluenesulfonic acid phenyl ester or the like may be used) as a photoacid generator. Positive chemically amplified resist composed of ethyl lactate is applied to a thickness of about 0.7 μm, and 1
Baking at 10 ° C. was performed for 90 seconds. After that, a film made of a hydrogenated product of a copolymer of methyltetracyclododecene and methylnorbornene is formed on the upper layer, and baked again on a hot plate at 60 ° C / 90 seconds, and then a wavelength of 2
Pattern exposure was performed with a 48 nm laser beam. Immediately after the pattern exposure, the above film formed on the resist was peeled off with xylene, heated at 90 ° C. for 90 seconds on a hot plate, and padded for 60 seconds with a 2.38% TMAH aqueous solution. When the cross-sectional shape was observed, the surface hardly-solubilized layer (eave) was smaller than in Comparative Example 1, but a slight amount was generated. (Comparative Example 3) A compound in which 40% of the hydroxyl groups of polyvinylphenol are t-butoxycarponoxylated on a silicon substrate, and triphenylsulfonium triflate (a p-toluenesulfonic acid phenyl ester or the like may be used) as a photoacid generator. Positive chemically amplified resist composed of ethyl lactate is applied to a thickness of about 0.7 μm, and 1
Baking at 10 ° C. was performed for 90 seconds. After that, a film made of a hydrogenated product of a copolymer of methyltetracyclododecene and methylnorbornene is formed on the upper layer, and baked again on a hot plate at 60 ° C / 90 seconds, and then a wavelength of 2
Pattern exposure was performed with a 48 nm laser beam. Immediately after the pattern exposure, heat treatment was performed on the resist at 90 ° C./90 seconds, the film formed on the resist was peeled off with xylene, and a paddle phenomenon was performed for 60 seconds with a 2.38% TMAH aqueous solution. When the cross-sectional shape was observed, the surface hardly-solubilized layer (eave) was smaller than in Comparative Example 1, but a slight amount was generated.

Next, each embodiment of the present invention will be described. (Example 1) A positive chemically amplified resist comprising a compound obtained by converting 40% of hydroxyl groups of polyvinylphenol into t-butoxycarponoxylation on a silicon substrate, triphenylsulfonium triflate as a photoacid generator, and ethyl lactate is used. Apply to a thickness of 0.7 μm and apply on a hot plate 11
The baking was performed at 0 ° C. for 90 seconds. After that, a film consisting of a hydrogenated product of a copolymer of methyltetracyclododecene and methylnorbornene and triphenylsulfonium triflate as a photoacid generator is formed on the upper layer, and baked again on a hot plate at 60 ° C / 90 seconds. Then, pattern exposure was performed with a laser beam having a wavelength of 248 nm. Immediately after the pattern exposure, the above film formed on the resist was peeled off with xylene, heated at 90 ° C. for 90 seconds on a hot plate, and padded for 60 seconds with a 2.38% TMAH aqueous solution. Observing the cross-sectional shape, Comparative Example 1
The surface insolubilized layer (overhang) that had occurred in Nos. 3 to 3 was not generated. (Example 2) A positive chemically amplified resist composed of a compound obtained by converting 40% of hydroxyl groups of polyvinylphenol into t-butoxycarponoxylation on a silicon substrate, triphenylsulfonium triflate as a photoacid generator, and ethyl lactate was used. Apply to a thickness of 0.7 μm and apply on a hot plate 11
The baking was performed at 0 ° C. for 90 seconds. After that, a film consisting of a hydrogenated product of a copolymer of methyltetracyclododecene and methylnorbornene and triphenylsulfonium triflate as a photoacid generator is formed on the upper layer, and baked again on a hot plate at 60 ° C / 90 seconds. Then, pattern exposure was performed with a laser beam having a wavelength of 248 nm. Immediately after the pattern exposure, heat treatment was performed on a hot plate at 90 ° C. for 90 seconds, the above film formed on the resist was peeled off with xylene, and a paddle phenomenon was performed for 60 seconds with a 2.38% TMAH aqueous solution. Observing the cross-sectional shape, Comparative Example 1
The surface insolubilized layer (overhang) that had occurred in Nos. 3 to 3 was not generated. (Example 3) A positive chemically amplified resist comprising a compound in which 40% of hydroxyl groups of polyvinylphenol are t-butoxycarponoxylated on a silicon substrate, p-toluenesulfonic acid phenyl ester as a photoacid generator, and ethyl lactate. Is applied to a thickness of about 0.7 μm, and 1 is applied on a hot plate.
Baking at 10 ° C. was performed for 90 seconds. After that, a film consisting of a hydrogenated product of a copolymer of methyltetracyclododecene and methylnorbornene and p-toluenesulfonic acid phenyl ester as a photoacid generator is formed on the upper layer, and the film is again placed on a hot plate at 60 ° C / 90 seconds. After baking
Pattern exposure was performed with a laser beam having a wavelength of 248 nm. Immediately after the pattern exposure, the above film formed on the resist was peeled off with xylene, heated at 90 ° C. for 90 seconds on a hot plate, and padded for 60 seconds with a 2.38% TMAH aqueous solution. When the cross-sectional shape was observed, the hardly-solubilized surface layer generated in Comparative Examples 1 to 3 was not generated. (Example 4) A positive chemically amplified resist comprising a compound in which 40% of hydroxyl groups of polyvinylphenol were t-butoxycarponoxylated on a silicon substrate, p-toluenesulfonic acid phenyl ester as a photoacid generator, and ethyl lactate. Is applied to a thickness of about 0.7 μm, and 1 is applied on a hot plate.
Baking at 10 ° C. was performed for 90 seconds. After that, a film consisting of a hydrogenated product of a copolymer of methyltetracyclododecene and methylnorbornene and p-toluenesulfonic acid phenyl ester as a photoacid generator is formed on the upper layer, and the film is again placed on a hot plate at 60 ° C / 90 seconds. After baking
Pattern exposure was performed with a laser beam having a wavelength of 248 nm. Immediately after the pattern exposure, heat treatment was performed on a hot plate at 90 ° C. for 90 seconds, the above film formed on the resist was peeled off with xylene, and a paddle phenomenon was performed for 60 seconds with a 2.38% TMAH aqueous solution. When the cross-sectional shape was observed, the hardly-solubilized surface layer generated in Comparative Examples 1 to 3 was not generated.

In the first to fourth embodiments, the case where the film is removed after the pattern exposure and after the heat treatment (after the pattern exposure) has been described. However, in the present invention, the film can be removed by dissolution in a developing solution. For example, it may be performed simultaneously with the development.

[0018]

According to the present invention, it is possible to prevent eaves from being formed on the positive resist pattern when finely forming the positive or negative resist pattern, and to round the negative resist pattern. The resist pattern line width can be stably formed in a desired dimension, and the pattern line width after etching can be stably formed in a desired dimension.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method of forming a resist pattern for explaining the principle of the present invention.

FIG. 2 is a diagram illustrating a problem of a conventional example.

[Explanation of symbols]

 1 substrate 2 chemically amplified resist 3 transparent film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichi Miyata 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (7)

[Claims] 1. A step of coating a chemically amplified resist on a substrate, a step of forming a transparent film containing a photo-acid generator on the chemically amplified resist, and a pattern exposure of the chemically amplified resist. A method of forming a resist pattern, comprising: a step of removing the transparent film; and a step of developing the chemically amplified resist that has been subjected to pattern exposure to form a chemically amplified resist pattern. 2. A step of applying a chemically amplified resist on a substrate, a step of forming a transparent film containing a photoacid generator on the chemically amplified resist, and a pattern exposure of the chemically amplified resist. A method of forming a resist pattern, comprising the steps of: developing the chemically amplified resist pattern-exposed to form a chemically amplified resist pattern, and removing the transparent film. 3. A heat treatment is performed between the resist coating step and the transparent film forming step, or a heat treatment is performed between the transparent film forming step and the pattern exposing step, or between both steps. 3. The method for forming a resist pattern according to claim 1, wherein the heat treatment is carried out by. 4. The method of forming a resist pattern according to claim 1, wherein heat treatment is performed between the transparent film removing step and the developing step. 5. The heat treatment is performed between the pattern exposing step and the transparent film removing step.
3. The method for forming a resist pattern according to 2). 6. The photoacid generator contained in the transparent film is
6. The method of forming a resist pattern according to claim 1, wherein the chemically amplified resist is made of the same material as the photo-acid generator contained in the resist. 7. The photo-acid generator contained in the transparent film is
6. The same acid as the photoacid generator contained in the chemically amplified resist is generated.
A method for forming a resist pattern as described.