JP2980821B2 - Fine pattern forming method - Google Patents

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 fine pattern used for manufacturing a semiconductor device or an integrated circuit on a semiconductor substrate.

[0002]

2. Description of the Related Art In recent years, as a method of forming a fine pattern in a manufacturing process of an IC, an LSI, or the like, a process using a short wavelength light source has been developed along with miniaturization of processing dimensions. In a lithography process using a short-wavelength light source, a chemically amplified resist that introduces the concept of chemical amplification is generally used. Chemically amplified resist consists of a multi-component substance containing an acid generator that generates an acid when irradiated with radiation and a compound that reacts with the acid, and changes the alkali dissolution characteristics using an acid-catalyzed reaction. This is for forming a finer resist pattern.

Hereinafter, a conventional method for forming a fine pattern will be described with reference to FIGS. 4 (a) and 4 (b).

First, as shown in FIG. 4A, a TiN film 2 is formed on a surface of a semiconductor substrate 1. The base 3 exists on the surface of the TiN film 2, and the surface of the TiN film 2 is basic.

Next, a positive chemically amplified resist (for example, WKR-PT- manufactured by Wako Pure Chemical Industries, Ltd.) is formed on the TiN film 2.
After applying 2) to form a resist film 4, the resist film 4 is exposed using a mask 5, and is baked and developed after exposure to obtain a resist pattern 6 as shown in FIG. .

However, as shown in FIG. 4 (b), there arises a problem that the resist pattern 6 is skirted and a good resist pattern cannot be obtained. When the above-mentioned positive type chemically amplified resist is used, the resist pattern has a skirt, and when the negative type chemically amplified resist is used, the resist pattern is bitten.
For this reason, there is a problem that the shape and the resolution of the resist pattern made of the chemically amplified resist are deteriorated, and the subsequent steps are adversely affected.

The above problem is particularly remarkable when a resist pattern is formed on a basic semiconductor substrate having a TiN film, a SiN film or the like formed on the surface, but when the surface of the semiconductor substrate is not basic. The above problem also occurs.

As a measure against the above-mentioned problem, a method of forming a thin film on a semiconductor substrate and forming a resist pattern on the thin film by using a chemically amplified resist (US Pat.
P. 5,219,788) have been proposed.

Further, a method of removing foreign matter on a semiconductor substrate by cleaning the surface of the semiconductor substrate with an acid is generally performed.

[0010]

However, the former method of forming a thin film on a semiconductor substrate is practically difficult to adopt from the viewpoint of the complexity of the process and the increase in cost.

In addition, it is difficult to completely prevent the bottom of the resist pattern from digging or biting by the latter method of removing foreign substances on the semiconductor substrate by washing with an acid. In a resist pattern formed on a basic semiconductor substrate on which a film or a SiN film is formed, it is difficult to prevent bottoming or biting.

[0012] In view of the above, the present invention can completely prevent bottoming or biting occurring in a resist pattern composed of a chemically amplified resist formed on a normal semiconductor substrate or a basic semiconductor substrate. An object of the present invention is to provide a method for forming a fine pattern.

[0013]

Means for Solving the Problems The following has been found as a result of studying the cause of the occurrence of tailing or biting occurring in a resist pattern made of a chemically amplified resist. That is, an acid is generated from the acid generator contained in the chemically amplified resist by exposure, but as described above, since a base is present on the surface of the TiN film, the acid generated from the acid generator is generated on the surface of the TiN film. Neutralized by base. For this reason, on the surface of the TiN film, the acid generated from the acid generator hardly contributes to the reaction of the compound that reacts with the acid contained in the chemically amplified resist. Therefore, a proper resist pattern cannot be obtained. That is, a basic substance such as ammonia is present on the surface of the semiconductor substrate on which the resist pattern has been caught or biting, or nitrogen atoms constituting the outermost surface of the film to be processed (TiN film) are isolated. Since the concentration of the electron pair is high, these substances consume the acid generated from the acid generator near the surface of the semiconductor substrate. As a result, the shape and resolution of the pattern made of the chemically amplified resist deteriorate.

[0014] The above problem is particularly encountered when a resist pattern is formed on a basic semiconductor substrate having a basic substance present on its surface or a basic semiconductor substrate having a TiN film, SiN film, etc. formed on its surface. Although notable, it also occurs when the surface of the semiconductor substrate is not basic. The cause is considered as follows. That is, since the chemically amplified resist is easily affected by impurities in the environment, it is affected by trace impurities present on the surface of the semiconductor substrate, and the reaction of the compound which reacts with acid is inhibited. Sinking or biting occurs, and the shape and resolution of the resist pattern deteriorate.

[0015] The present invention has been made based on the above findings, and provides an acid to the surface of a semiconductor substrate to provide
It promotes the reaction of a substance that reacts with an acid on the surface of the semiconductor substrate.

Specifically, a solution taken by the first aspect of the present invention is to provide a method for forming a fine pattern on a semiconductor substrate by using an organic
Carboxylic acid, organic carboxylic anhydride, organic dicarboxylic acid
And a first step of supplying an acidic solution containing at least one of organic sulfonic acid, and on the semiconductor substrate,
A second step of applying a chemically amplified resist containing an acid generator that generates an acid when irradiated with a radiation and a compound that reacts with the acid to form a resist film, and exposing the resist film to radiation. And a fourth step of developing a resist pattern by developing the exposed resist film.

According to a second aspect of the present invention, in the first aspect, the first step comprises irradiating an acid generator solution containing an acid generator which generates an acid when irradiated with radiation. Before
An additional feature is provided that includes a step of supplying the acidic solution onto the semiconductor substrate while changing the acid generator solution to an acidic solution by generating an acid from the acid generator.

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

The invention of claim 3, in the configuration of claim 1, the semiconductor substrate in the first step is to add the configuration that basic film is formed on the surface thereof.

[0027]

[0028]

Examples of the acidic compound used in the acidic solution supplied to the surface of the semiconductor substrate include formic acid, acetic acid, propionic acid, acrylic acid, butyric acid, isobutyric acid, methacrylic acid, oleic acid, lactic acid, monochloroacetic acid, Carboxylic acid or carboxylic anhydride such as dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, oxalic acid, malonic acid, acetic anhydride, propionic anhydride, and methanesulfonic acid;
Sulfonic acids such as ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, p-toluenesulfonic acid, and benzenesulfonic acid.

Examples of the acid generator contained in the acid generator solution that generates an acid upon irradiation with light or heating include, for example,
Diphenyldisulfone, triphenylsulfonium trifluoromethanesulfonate, diphenyliodonium trifluoromethanesulfonate, bis (p-toluenesulfonyl) diazomethane, bis (p-chlorobenzenesulfonyl) diazomethane, 1,2,3-tris (methanesulfonyloxy) benzene, 1 , 3,5-Tris (trifluoromethanesulfonyloxy) benzene, p-toluenesulfonic acid
-o-nitrobenzyl, 2,6-dinitrobenzyl p-toluenesulfonate, 1,1-bis (p-chlorophenyl) -2,2,
2-trichloroethane, bis (ter-butylsulfonyl) diazomethane, biscyclohexylsulfonyldiazomethane, 1,1-bis (p-chlorophenyl) -2,2-dichloroethane, 2-chloro-6- (trichloromethyl) pyridine, diphenyl-p -Methylphenacylsulfonium-p-toluenesulfonate, diphenyl-2,5-dimethoxyphenacylsulfonium-p-toluenesulfonate, 2-methyl-2-p-
Examples include, but are not limited to, toluenesulfonylpropiophenone.

As a solvent for dissolving the above-mentioned acidic compound or acid generator, any solvent may be used as long as it can dissolve these substances. Methylcellosolve acetate, ethylcellosolve acetate, propylene glycol monomethyl ether acetate, Propylene glycol monoethyl ether acetate, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, 2-ethoxyethyl acetate, butyl acetate, isopropanol, 2-methoxypropanol, ethylene glycol, propylene glycol,
Examples thereof include methyl 3-methoxypropionate, ethyl 3-methoxypropionate, 2-heptanone, and diethylene glycol dimethyl ether.

The concentration of the acidic solution is not particularly limited as long as the acidic compound or the acid generator is dissolved, but is usually 0.1 to 50% by weight, preferably 0.5 to 50% by weight.
It is in the range of 25% by weight.

[0033]

[Action] The arrangement of claim 1, on a semiconductor substrate, Yes
Carboxylic acid, organic carboxylic anhydride, organic dicarboxylic acid
After supplying an acid solution containing at least one of an acid and an organic sulfonic acid , a chemically amplified resist is applied to form a resist film. In the vicinity of the interface with the semiconductor substrate in the above, both the acid generated from the acid generator contained in the chemically amplified resist and the acid contained in the acidic solution are included in the chemically amplified resist. And the inactivation of the acid generated from the acid generator contained in the chemically amplified resist is prevented.

According to the structure of the second aspect, the first step is to irradiate an acid generator solution containing an acid generator which generates an acid when irradiated with radiation to convert the acid from the acid generator. Since the method includes a step of supplying the acidic solution onto the semiconductor substrate while changing the acid generator solution to an acidic solution by generating the acid generator solution, the acidic solution can be easily and reliably supplied onto the semiconductor substrate.

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

According to the third aspect of the present invention , since the surface of the semiconductor substrate in the first step has a basic film formed thereon, the surface of the semiconductor substrate is neutralized or the surface of the semiconductor substrate becomes basic. Can be weakened.

[0043]

[0044]

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a fine pattern according to one embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 Hereinafter, a method for forming a fine pattern according to a first embodiment of the present invention will be described with reference to FIGS. 1 (a) to 1 (e). The first embodiment shows a method of forming a fine pattern on a semiconductor substrate 1 having a TiN film 2 as a film to be processed on the surface.

First, as shown in FIG. 1A, a TiN film 2 is formed on the surface of a semiconductor substrate 1. Since the TiN film 2 has many lone electron pairs of nitrogen atoms and a high ammonia concentration on the surface, the surface of the TiN film 2 is basic.
That is, the base 3 exists on the surface of the TiN film 2.

Next, dichloroacetic acid was dissolved in ethyl lactate to prepare an acidic solution consisting of a 20% by weight dichloroacetic acid solution, and the acidic solution was placed on the semiconductor substrate 1 as shown in FIG. The entire surface of the semiconductor substrate 1 is immersed in the acidic solution 2 by dropping the solution, and is left in this state for 20 seconds.
Thereafter, when spin drying is performed on the acidic solution 2, T
Since the base 3 on the surface of the iN film 2 is neutralized by the acid 8 in the acidic solution 7, the TiN film 2 whose surface is neutralized can be obtained.

Next, as shown in FIG. 1C, a two-component positive chemically amplified resist 4 such as WKR-PT-2 (manufactured by Wako Pure Chemical Industries, Ltd.) is spin-coated on the TiN film 2. Pre-baking is performed for 90 seconds at a temperature of 90 ° C. to form a resist film 4.

Next, as shown in FIG.
After exposure using the KrF excimer laser 9 is performed, baking is performed for 90 seconds at a temperature of 100 ° C. for 90 seconds. By the post-exposure baking, the decomposition reaction of the polymer in the chemically amplified resist by the acid proceeds in the exposed portion of the resist film 4. That is, the decomposition reaction of the compound having the property of being decomposed by an acid contained in the chemically amplified resist proceeds. Thereafter, when development is performed for 60 seconds with an organic alkali aqueous solution, as shown in FIG.
A good resist pattern 6 without tailing was obtained.

As described above, according to the first embodiment, before applying the chemically amplified resist 4, the semiconductor substrate 1 having a basic surface is immersed in the acidic solution 7, and the acidic solution 7 is dried. As a result, the basic surface of the semiconductor substrate 1 is neutralized.
Can be formed.

(Examples 2 to 8) In place of the acidic solution of the first embodiment, an acidic solution shown in Table 1 was prepared.
In the same manner as described above, a pattern was formed by neutralizing the surface of the semiconductor substrate 1.

[0053]

[Table 1]

As a result, in each of the examples, a good pattern with no skirt was formed as in the first example.

Embodiment 9 Hereinafter, a fine pattern forming method according to a ninth embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. The ninth embodiment shows a method of forming a fine pattern on a semiconductor substrate 1 having no basic film to be processed on the surface.

First, 5% by weight of diphenyldisulfone is dissolved in propylene glycol monomethyl ether acetate to obtain an acid generator solution comprising a disulfone solution containing the acid generator 11 in the solution. Next, the acid generator solution was dropped on the semiconductor substrate 1 whose outermost surface was Si, and FIG.
As shown in (a), after the entire surface of the semiconductor substrate 1 is immersed in the acid generator solution 10, the acid generator solution 10 is spin-dried. In this case, FIG.
As shown in FIG.
Part of the acid generator 11 composed of diphenyldisulfone therein remains.

Next, as shown in FIG. 2C, a two-component positive chemically amplified resist, for example, WKR-PT-2 (manufactured by Wako Pure Chemical Industries, Ltd.) is spin-coated on the semiconductor substrate 1. Pre-baking is performed for 90 seconds at a temperature of 90 ° C. to form a resist film 4. By doing so, a resist film 4 in which the concentration of the acid generator 11 is high only on the surface of the semiconductor substrate 1 can be obtained.

Next, as shown in FIG. 2D, when the resist film 4 is exposed by a KrF excimer laser 9 using a mask 5, an acid contained in the resist film 4 is generated in the exposed portion. At the same time as the acid is generated from the agent,
Acid is generated from the acid generator 11. Thereafter, post-exposure baking is performed at a temperature of 100 ° C. for 90 seconds. By the post-exposure baking, the decomposition reaction of the polymer of the chemically amplified resist 4 by the acid proceeds. That is, the decomposition reaction of the compound having the property of being decomposed by an acid contained in the chemically amplified resist proceeds. Then, TMAH: 2.38
% Of the developing solution for 60 seconds,
As shown in (e), a good resist pattern 6 without skirting was obtained.

As described above, according to the ninth embodiment, before applying the chemically amplified resist 4 to form the resist film 4, the surface of the semiconductor substrate 1 is treated with a solution containing an acid generator. Therefore, a good resist pattern 6 without skirting can be formed.

(Examples 10 to 15) In place of the acid generator of the ninth example, acid generator solutions shown in Table 2 were prepared, and a pattern was formed in the same manner as in the ninth example.

[0061]

[Table 2]

As a result, in each of the five embodiments, as in the ninth embodiment, it was possible to form a good pattern with no skirting or biting.

Embodiment 16 Hereinafter, a fine pattern forming method according to a sixteenth embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

The sixteenth embodiment shows a method of forming a fine pattern on a semiconductor substrate 1 having a TiN film 2 as a film to be processed on the surface, as in the first embodiment.

When the TiN film 2 is formed on the surface of the semiconductor substrate 1 in the same manner as in the first embodiment, the surface of the TiN film 2 is basic, and the base 3 exists.

Next, as in the ninth embodiment, 5% of diphenyldisulfone was dissolved in propion glycol monomethyl ether acetate to obtain an acid generator solution 10 composed of a disulfone solution containing an acid generator 11 in the solution. The acid generator solution 10 is stored in the container 12 and dropped on the TiN film 2 through the liquid supply pipe 13. A liquid reservoir 14 is provided in the middle of the liquid supply pipe 13, and the liquid reservoir 14 is irradiated with far ultraviolet rays.
Thereby, the acid 8 is generated from the acid generator in the acid generator solution 10, and the acidic solution 7 containing the acid 8 is supplied to the surface of the TiN film 2.

After the acidic solution 7 is dropped on the semiconductor substrate 1 to immerse the entire surface of the semiconductor substrate 1 in the acidic solution 7, the acidic solution 7 is spin-dried. In this way, T
Since the base 3 in the iN film 2 reacts with the acid 8 in the acidic solution 7 to be neutralized, a TiN film 2 having a neutralized surface as shown in FIG. 3B can be obtained.

Next, in the same manner as in the first embodiment, a two-component positive chemically amplified resist, for example, WKR-PT-2 (manufactured by Wako Pure Chemical Industries, Ltd.) is spin-coated on the TiN film 2, Pre-baking is performed for 90 seconds at a temperature of 90 ° C. to form a resist film. Then, after exposing the resist film with a KrF excimer laser,
A post-exposure bake is performed at a temperature of 0 ° C. for 90 seconds.
By this post-exposure baking, the decomposition reaction of the polymer in the chemically amplified resist by the acid proceeds. Thereafter, when development was performed with an organic alkali aqueous solution, a favorable resist pattern without tailing could be obtained.

As described above, according to the sixteenth embodiment, after irradiating the acid generator solution 10 with far ultraviolet rays to generate an acid to obtain the acid solution 7, the semiconductor substrate 1 is immersed in the acid solution 7. Therefore, a good pattern without tailing can be formed without being affected by the basicity of the surface of the semiconductor substrate 1.

(Examples 17 to 22) The solutions shown in Table 2 were prepared in place of the acid generator of the sixteenth example, and pattern formation was performed in the same manner as in the sixteenth example. In the example, similar to the sixteenth example, a good pattern without skirting could be formed.

The first to eighth embodiments, and the sixteenth to eighteenth embodiments
In the twenty-second embodiment, the case where the TiN film is the outermost surface has been described. However, the present invention is applicable to a semiconductor substrate in which other inorganic or organic films are formed on the surface and the surface is basic. can do.

Even if the surface of the semiconductor substrate does not show basicity, the present invention can be applied when the surface of the semiconductor substrate is contaminated by a small amount of impurities in a clean room environment. Hemming or biting can be reliably prevented.

In the first to twenty-second embodiments, the acidic solution is supplied when the surface of the semiconductor substrate is basic, and the acid generator solution is supplied when the surface of the semiconductor substrate does not exhibit basicity. , But is not limited to these. However, when the surface of the semiconductor substrate is basic, it is preferable to supply an acidic solution to neutralize the entire surface of the semiconductor substrate in advance. Further, when the surface of the semiconductor substrate does not show basicity, it is better to supply the acid generator solution and generate the acid only in the exposed portion, so that the acid does not adversely affect the chemically amplified resist. It is preferred.

Further, in the first to twenty-second embodiments,
As the chemically amplified resist, WKR-PT-2, which is a two-component chemically amplified positive resist, was used. However, any other chemically amplified resist whose solubility changes due to an acid catalyzed reaction may be used. Positive resist (for example, O
The same effect can be obtained by using a three-component positive resist (for example, DX46 made by Hoechst) or a negative resist (for example, XP8843 made by Shipley) manufactured by CG Corporation.

[0075]

According to the method for forming a fine pattern according to the first aspect of the present invention, the acid and the acid solution generated from the acid generator contained in the chemically amplified resist near the interface between the resist film and the semiconductor substrate are included. Both of the acids contribute to the reaction of the acid-reactive compound contained in the chemically amplified resist and react with the acid to prevent deactivation of the acid generated from the acid generator contained in the chemically amplified resist. Since the reaction of the compound proceeds to the same extent as other sites in the resist film, it is possible to form a good pattern having a vertical cross section without skirting or biting.

According to the method for forming a fine pattern according to the second aspect of the present invention, the acid solution can be supplied onto the semiconductor substrate while changing the acid generator solution to the acidic solution. Can be supplied.

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

According to the method for forming a fine pattern according to the third aspect of the present invention, even when the surface of the semiconductor substrate is basic, the basicity is neutralized or weakened, so that a vertical cross section without bottoming or digging is provided. And a good pattern having the following can be formed.

[0084]

[0085]

As described above, the method of forming a fine pattern according to the present invention can be performed by a conventional coating apparatus, unlike the method of forming a film under a resist film.
Since the burden on the process is small and low cost can be realized,
Great industrial value.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing each step of a method for forming a fine pattern according to first to eighth embodiments of the present invention.

FIG. 2 is a sectional view showing each step of a fine pattern forming method according to ninth to fifteenth embodiments of the present invention.

FIG. 3 is a cross-sectional view showing each step of a fine pattern forming method according to sixteenth to twenty-second embodiments of the present invention.

FIG. 4 is a cross-sectional view showing each step of a conventional fine pattern forming method.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 TiN film 3 base 4 resist film 5 mask 6 resist pattern 7 acid solution 8 acid 9 KrF excimer laser light 10 acid generator solution 11 acid generator 12 container 13 liquid supply pipe 14 liquid reservoir

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/027 G03F 7/028 H01L 21/26

Claims (3)

(57) [Claims] An organic carboxylic acid is provided on a semiconductor substrate.
Carboxylic anhydride, organic dicarboxylic acid and organic sulfo
A first step of supplying an acidic solution containing at least one of an acid, and an acid generator that generates an acid when irradiated with radiation and a compound that reacts with the acid on the semiconductor substrate. A second step of applying a chemically amplified resist to form a resist film, a third step of irradiating the resist film with radiation and exposing the resist film, and developing the exposed resist film to form a resist pattern A method for forming a fine pattern, comprising: a fourth step. 2. The method according to claim 1, wherein the first step includes irradiating radiation.
And irradiating the acid generator solution containing an acid generator that generates an acid with radiation to generate an acid from the acid generator, thereby changing the acid generator solution to an acidic solution, The method for forming a fine pattern according to claim 1, further comprising a step of supplying the fine pattern on a semiconductor substrate. 3. The semiconductor substrate in the first step,
2. The method according to claim 1, wherein a basic film is formed on the surface.