JPH06214402A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To improve the heat resistance of resist patterns without entailing the dimensional fluctuation of these resist patterns. CONSTITUTION:A chemical amplification type resist 2 consisting of a radiation sensitive material essentially consisting of a high-polymer compd. or monomolecular compd. in which at least a part of phenolic hydroxyl groups are substd. by protective groups easily being eliminated by the effect of an acid is applied on a semiconductor substrate 1. This chemical amplification type resist 2 is then exposed or irradiated with radiations and thereafter, the chemical amplification type resist 2 is developed, by which the resist patterns 2A are formed. The resist patterns 2A are thereafter irradiated with the radiations over the entire surface in the state of maintaining the temp. of the semiconductor substrate 1 at the glass transition point of the chemical amplification type resist 2 or below to eliminate the protective groups in the chemical amplification type resist 2, by which the heat resistance of the resist patterns 2 is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine pattern forming method for manufacturing a semiconductor device or an integrated circuit device.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of ICs or LSIs, pattern formation is performed by photolithography using ultraviolet rays. On the other hand, along with the miniaturization of semiconductor devices, the use of short-wavelength light sources as ultraviolet light sources has been promoted.

When a short-wavelength light source is used for photolithography, a chemically amplified resist which has high sensitivity and high resolution has been developed as a resist to be used (eg, O.NALAMASU et al., Pr.
oc. SPIE, Vol. 1262, P.I. 32 (199
0)). This chemically amplified resist is a multi-component substance containing a photo-acid generator that generates an acid when irradiated with radiation and a compound that reacts with the acid. As a polymer compound that reacts with an acid, for example, a polymer compound having a structure such as [Chemical Formula 1] is known.

[0004]

[Chemical 1]

Here, R is an alkoxycarbonyl group, an alkyl group, an alkoxyalkyl group, an alkylsilyl group,
A tetrahydropyranyl group, an alkoxycarbonylmethyl group or the like, which easily causes a decomposition reaction with an acid. As described above, the chemically amplified resist is mainly composed of a polymer compound having a low absorptance of light in a short wavelength region, such as a polyvinylphenol derivative. Therefore, the chemically amplified resist has high sensitivity because the transparency of the resist is increased and the reaction of the resist proceeds due to a chain reaction by an acid catalyst, and the resist is excellent in resolution. Therefore, the chemically amplified resist is regarded as a promising material for forming a fine pattern using a short wavelength light source.

An example of a conventional fine pattern forming method using a chemically amplified resist will be described below with reference to the drawings based on FIGS. 6 (a) to 6 (d).

First, a chemically amplified resist having the following material composition is prepared.

Poly (p-tert-butoxycarbonyloxystyrene-p-hydroxystyrene) (weight average molecular weight of about 9500, monomer unit ratio of about 1: 1) 6.0 g triphenylsulfonium hexafluorophosphate 0.3 g diethylene glycol dimethyl ether 13. 7g Next, as shown in FIG. 6 (a), a chemically amplified resist made of the above-mentioned composition material was dropped on the semiconductor substrate 1 to perform spin coating, and then the hot plate 6 was used to perform 1 The resist film 2 having a film thickness of 1.0 μm is formed by baking for 1 minute. Next, the resist film 2 is irradiated with the KrF excimer laser light 4 through the mask 3.

Next, as shown in FIG. 6B, the resist film 2 is baked by a hot plate 6 at a temperature of 100 ° C. for 1 minute, and then developed by an organic alkaline aqueous solution for 1 minute. By doing so, a resist pattern 2A is obtained.

Next, as shown in FIG. 6C, the entire surface of the resist pattern 2A is irradiated with deep ultraviolet rays 7 for 2 minutes, and the resist pattern 2A is heat-treated by the hot plate 6. As a result, the temperature of the semiconductor substrate 1 rises to 160 ° C., for example.

Without irradiating the far ultraviolet rays 7, for example, 16
When the heat treatment is performed at 0 ° C. or higher, the polyvinylphenol derivative, which is the main component of the chemically amplified resist, usually has a low glass transition point, for example, 160 ° C. or lower.
As shown in (d), the pattern shape of the resist pattern 2A deteriorates, and accurate pattern transfer to the semiconductor substrate 1 becomes impossible.

As described above, since the chemically amplified resist has high transparency, high sensitivity and high resolution, the pattern forming method using the chemically amplified resist is effective for forming a fine pattern. However, the chemically amplified resist has a problem of low heat resistance. Therefore, as shown in FIG. 6C, a method has been proposed in which the resist pattern 2A is cured by performing a heat treatment involving irradiation with deep ultraviolet rays.

[0013]

However, the present inventors have recently found that when the resist pattern 2A made of a chemically amplified resist is subjected to a heat treatment accompanied by deep ultraviolet irradiation, the polymer component of the chemically amplified resist becomes deep. Condensed by ultraviolet rays
It was found that the size of the resist pattern 2A is reduced due to the dissociation.

FIG. 7 is a graph showing the measured dimensions of the resist pattern 2A formed by the fine pattern forming method described above after development and the measured dimensions after heat treatment. As shown in FIG. 7, the size of the resist pattern 2A varies around 10% after development and after heat treatment.

Further, since the above-mentioned dimensional variation varies depending on the dimension of the resist pattern 2A, it is difficult to accurately control the dimension of the resist pattern 2A after the heat treatment.

In view of the above, it is an object of the present invention to improve the heat resistance of a resist pattern without dimensional variation of the resist pattern.

[0017]

According to the present invention, when a chemically amplified resist is entirely irradiated with radiation while the temperature of a semiconductor substrate is kept below the glass transition point of the chemically amplified resist,
The inventors have found that the heat resistance of the resist pattern is improved without dimensional variation of the resist pattern, and have been made based on this finding.

Specifically, the means for solving the problems according to the invention of claim 1 is that the method for forming a fine pattern is such that at least a part of the phenolic hydroxyl groups is substituted on the semiconductor substrate by a protective group which is easily eliminated by the action of an acid. A resist coating step of coating a chemically amplified resist made of a radiation sensitive material containing a polymer compound or a monomolecular compound as a main component, and the above chemically amplified resist after being exposed or irradiated with radiation, By developing the amplified resist,
A resist pattern forming step of forming a resist pattern made of the chemically amplified resist, and irradiating the entire surface of the resist pattern with radiation in a state where the temperature of the semiconductor substrate is kept at a glass transition point of the chemically amplified resist or less, And a heat resistance imparting step of improving the heat resistance of the resist pattern by removing the protective group in the chemically amplified resist.

According to a second aspect of the present invention, in the structure according to the first aspect, in the heat resistance imparting step, the resist pattern is irradiated with radiation while the temperature of the semiconductor substrate is maintained at a temperature not higher than the glass transition point of the chemically amplified resist. The step of heating the semiconductor substrate after irradiating the entire surface thereof with the resist pattern is a step of improving the heat resistance of the resist pattern.

According to a third aspect of the present invention, in addition to the structure of the first or second aspect, the entire surface irradiation of the radiation in the heat resistance imparting step is performed without baking the semiconductor substrate.

According to the invention of claim 4, in addition to the constitutions of claims 1 to 3, the radiation in the heat resistance imparting step is far ultraviolet rays.

According to a fifth aspect of the present invention, in addition to the constitutions of the first to fourth aspects, the energy amount of radiation in the heat resistance imparting step is 10,000 mJ / cm ² or less.

According to a sixth aspect of the present invention, in the resist pattern forming step according to the first to fifth aspects, the chemically amplified resist is exposed after the chemically amplified resist is exposed or irradiated with radiation. A configuration is added in which the acid generated in the chemically amplified resist is heated to diffuse it, and then the chemically amplified resist is developed to form a resist pattern made of the chemically amplified resist. To do.

Specific examples of the polymer compound in which at least a part of the phenolic hydroxyl group is substituted with a protecting group which is easily eliminated by the action of an acid include, for example, poly (p-tert-butoxycarbonyloxystyrene) and poly (p -tert-butoxystyrene), poly (p-tetrahydropyranyloxystyrene), poly (p- (1-ethoxyethoxy) styrene), poly (p- (1-methoxy-1-methylethoxy) styrene), poly ( p-trimethylsilyloxystyrene),
Poly (p-tert-butoxycarbonyloxystyrene-p-
Hydroxystyrene), poly (p-tert-butoxystyrene-p-hydroxystyrene), poly (p-tetrahydropyranyloxystyrene-p-hydroxystyrene), poly (p- (1-ethoxyethoxy) styrene-p-hydroxy Styrene), poly (p- (1-methoxy-1-methylethoxy))
Styrene-p-hydroxystyrene), poly (p-trimethylsilyloxystyrene-p-hydroxystyrene), poly (p-tert-butoxycarbonylmethoxystyrene-p-hydroxystyrene), etc., but are not limited to these. is not.

Further, specific examples of the monomolecular compound in which all of the phenolic hydroxyl groups are substituted with a protecting group which is easily eliminated by the action of an acid include, for example, 2,2-bis (4-tetrahydropyranyloxyphenyl) propane. , 2,2-bis (4-ter
t-butoxyphenyl) propane, 2,2-bis (4-tert-butoxycarbonyloxyphenyl) propane, 2,2-bis (4
-(1-Ethoxyethoxy) phenyl) propane, 3,4-dihydro-4- (2,4-di- (1-tetrahydropyranyloxy) phenyl) -7- (1-tetrahydropyranyloxy) -2, 2,4-trimethyl-2H-1-benzopyran, 3,4-dihydro-4- (2,4-di-
(1-tert-Butoxy) phenyl) -7- (1-tert-butoxy)-
2,2,4-Trimethyl-2H-1-benzopyran, 3,4-dihydro-
4- (2,4-di- (1-ethoxyethoxy) phenyl) -7- (1-ethoxyethoxy) -2,2,4-trimethyl-2H-1-1-benzopyran and the like can be mentioned. It is not limited.

[0026]

According to the constitution of claim 1, even when a chemically amplified resist having a polyvinyl glass derivative as a main polymer and a low glass transition point is used, heat resistance using a derivative of bisphenol A or trihydroxybenzopyran as a dissolution inhibitor is improved. Even if a low chemically amplified resist is used, it is possible to provide the resist pattern with heat resistance required when dry etching a semiconductor substrate. In particular, by irradiating the resist pattern with radiation while keeping the temperature of the semiconductor substrate below the glass transition point of the chemically amplified resist, the hydroxyl group of polyvinylphenol, which is the skeleton of the main polymer, or bisphenol A, which is a dissolution inhibiting compound, is used. Of the protective group, which is substituted with the hydroxyl group of OH and the hydroxyl group of trihydroxybenzopyran and causes heat resistance deterioration, without causing polymerization of the main polymer or the dissolution inhibitor as shown in [Chemical formula 2] or [Chemical formula 3] below. Is to be desorbed according to the formula.
As a result, the polyvinylphenol derivative can be changed to polyvinylphenol having a high glass transition point, and the bisphenol A or trihydroxybenzopyran derivative can be changed to a bisphenol A or trihydroxybenzopyran compound having good heat resistance.

In the formulas [Chemical Formula 2] and [Chemical Formula 3], a proton is generated from the acid generator in the chemically amplified resist by radiation, and the proton removes the protective group of the polymer or the dissolution inhibitor. It is shown that.

[0028]

[Chemical 2]

[0029]

[Chemical 3]

According to the structure of claim 2, by heating the semiconductor substrate after irradiating the resist pattern with the whole surface of the radiation, the protective groups which have not been removed by the whole surface irradiation of the radiation are completely removed. The property is improved.

According to the structure of claim 3, since the semiconductor substrate is not baked in the heat resistance imparting step, the throughput is improved as compared with the case where baking is performed.

According to the structure of claim 4, since deep ultraviolet rays are used as the radiation in the heat resistance imparting step, the handling of the radiation is simplified and the elimination reaction of the protective group is efficiently carried out.

According to the structure of claim 5, the energy amount of radiation in the heat resistance imparting step is 10,000 mJ / cm ^2.
Since the heat resistance of the resist pattern is improved with a small amount of energy, the amount of dimensional variation of the resist pattern can be reliably suppressed.

According to the sixth aspect of the invention, in the resist pattern forming step, the chemically amplified resist which has been exposed or irradiated with radiation is heated, so that the acid generated in the chemically amplified resist by exposure or irradiation is diffused. be able to.

Japanese Patent Publication No. 4-63535 discloses a post-baking method using deep UV irradiation, but this method describes not a chemically amplified resist but a novolac-based resist (OFPR-800). However, it is completely different from the method for improving heat resistance using the novel concept of elimination of the protective group of the chemically amplified resist of the present invention.

Further, Japanese Patent Publication No. 58650/1993 describes light irradiation and heat treatment. In this method, a main chain cleavage type resist (eg polymethylmethacrylate, polymethylisopropenylketone, etc.) was used. This is for achieving taper etching of the pattern, and is completely different from the heat resistance improving method of the present invention, which uses a new concept of protecting group elimination of a chemically amplified resist.

[0037]

EXAMPLES Before describing the examples of the present invention, the outline of the present invention will be described.

In the present invention, when a fine pattern is formed using a chemically amplified resist containing a polymer compound having insufficient heat resistance as a main component, the temperature of the semiconductor substrate is set to the glass transition of the chemically amplified resist. Keeping below the point,
The heat resistance of the resist pattern is improved by irradiating the developed resist pattern with radiation over the entire surface to promote the chemical change of the chemically amplified resist forming the resist pattern. That is, it is intended to provide the resist pattern with heat resistance necessary for dry etching without curing the chemically amplified resist, thereby solving the above problems.

When forming the resist pattern,
In order to diffuse the acid generated in the chemically amplified resist,
The chemically amplified resist that has been exposed or irradiated with radiation may be heated.

In the heat resistance imparting step, the temperature of the semiconductor substrate during the overall irradiation with radiation must be kept below the glass transition point of the chemically amplified resist in order to avoid thermal deformation of the chemically amplified resist. As a method of keeping the semiconductor substrate at the glass transition point or lower of the chemically amplified resist, the temperature of the semiconductor substrate may be adjusted with cooling water or the like.

The main polymer of the chemically amplified resist is
It must be one that causes a chemical change due to radiation, and that the chemical change raises the glass transition point.
For example, a compound in which a hydroxyl group of polyvinylphenol is substituted with an alkoxy group or the like (a compound represented by [Chemical Formula 1]) has the above-described properties. That is, the main polymer, which had a low glass transition point because the phenolic acid hydroxyl group was substituted with a protective group, was changed to polyvinylphenol upon irradiation with radiation, and the glass transition point increased. Therefore, even if a chemically amplified resist having low heat resistance is used, a highly heat resistant resist pattern can be easily formed by irradiation with radiation. Further, since the temperature of the semiconductor substrate is kept at the glass transition point of the chemically amplified resist or lower, the resist pattern is not hardened, so that the dimensional variation of the resist pattern is suppressed to the minimum.

As the radiation, for example, deep ultraviolet rays, Kr
Any of F excimer laser light, ArF excimer laser light, electron beam, X-ray and the like may be used as long as they cause the above-mentioned chemical changes, but when using short wavelength radiation,
The above reaction occurs efficiently. Of the short-wavelength radiation, far-ultraviolet rays are effective because they are the easiest to handle and can efficiently cause the above-mentioned chemical reaction.

FIGS. 2 (a) and 2 (b) show changes in infrared spectrum when a chemically amplified resist containing a polyvinylphenol derivative as a main component is irradiated with radioactivity according to the present invention. Yes, FIG. 2 (a) shows before irradiation with radiation, and FIG. 2 (b) shows after irradiation with radiation. 2A and 2B, the horizontal axis represents the wave number of light and the vertical axis represents the absorption amount of light. Figure 2 (a)
As is clear from the comparison between FIG. 2 and FIG. 2B, the absorption of light near 1120 cm ^−1, which is derived from the C—O—C stretching vibration of the protective group observed before the irradiation of the radiation, causes the irradiation of the radiation. Not observed later. This indicates that the elimination reaction of the protective group proceeded by the irradiation of radiation.

In the present invention, since the heat treatment for hardening the chemically amplified resist does not have to be performed, irradiation of high temperature and high power radiation is unnecessary, and the throughput is improved.

FIGS. 3 (a) and 3 (b) show the amount of dimensional variation of a 0.5 μm line-and-space pattern when a chemically amplified resist containing a polyvinylphenol derivative as a main component is used. FIG. 3 (a) is based on the conventional method, and FIG. 3 (b) is based on the method of the present invention. In FIGS. 3A and 3B, the white circles show the pattern dimensions before the heat treatment, and the black circles show the pattern dimensions after the heat treatment. According to the conventional method, a size reduction of 10% or more with respect to the pattern size is caused, but according to the present invention, the size variation amount is small, and the size variation amount can be suppressed within 5%.

FIGS. 4 (a) and 4 (b) are schematic views of the cross-sectional shape of the 0.5 μm contact hole in the case of using a chemically amplified resist containing a polyvinylphenol derivative as a main component. 4) is based on the conventional method, and FIG. 4B is based on the method of the present invention.
In a resist pattern such as a contact hole in which the remaining area of the resist is large, the volume reduction of the resist has a great influence on the resist pattern. According to the conventional method, since the volume of the resist is greatly reduced, the reduction of the resist is observed on the upper portion of the resist which is not in close contact with the semiconductor substrate, and the resist pattern has a Y-shaped cross section. Such deterioration of the pattern shape adversely affects later etching of the semiconductor substrate. On the other hand, by using the method of the present invention, the verticality of the pattern can be maintained.

As described above, according to the present invention, it is possible to easily form a fine pattern having accurate dimensions and high heat resistance.

In the resist pattern forming step,
When heat treatment is performed after irradiating the chemically amplified resist with radiation, the radiation irradiation accelerates the elimination of the protective groups in the undecomposed chemically amplified resist and raises the glass transition point. Is obtained. The heat treatment temperature at this time is preferably not higher than the glass transition point of the chemically amplified resist after irradiation with radiation.

FIG. 5 shows 0.35 formed by a chemically amplified resist whose main component is a polyvinylphenol derivative.
For μm line and space resist pattern,
Semiconductor substrate temperature is 25 ° C, 100 ° C, 160 ° C and 2
The dimensional variation of the resist pattern when far-ultraviolet irradiation is performed under the condition of 00 ° C is shown.

The 0.35 μm rule is a pattern size which will become the mainstream in the future, and the practical size variation is 10
It is considered to be within%. Therefore, when the temperature of the semiconductor substrate is equal to or lower than the glass transition point of the chemically amplified resist, the upper limit of the irradiation energy amount is about 10,000 mJ / cm ² at which the size reduction of the 0.35 μm pattern is 10% or less. Is.

The lower limit of the amount of irradiation energy is the amount of energy for causing the above-mentioned chemical reaction, that is, after exposing or irradiating a resist film having an infinite area, heating is performed if necessary, and then development is performed. The amount is such that the film thickness of the resist film becomes zero.

Although it depends on the illuminance of the radiation used, the radiation dose is 20 mW /
It is desirable to use one having a size of about cm ² or more. For example, using radiation of 200 mW / cm ² , 20 mJ / cm
^When a resist film whose film thickness becomes 0 depending on the irradiation energy amount of ² , the irradiation time is 0.1 seconds or more and 50 seconds or less.

The upper and lower limits of the irradiation energy amount and the irradiation time have been described in the case of far ultraviolet rays, but the same applies when other radiation is used. The upper and lower limits of the irradiation energy amount described above may differ depending on the composition of the chemically amplified resist, the type of radiation, and the like, and are not limited thereto.

(First Embodiment) A fine pattern forming method according to the first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of each step showing a fine pattern forming method according to the first embodiment of the present invention.

First, a chemically amplified resist having the following first material composition was prepared.

(First Material Composition) Poly (p-tert-butoxycarbonyloxystyrene-p-hydroxystyrene) (weight average molecular weight of about 9500, monomer unit ratio of about 1: 1) 6.0 g triphenylsulfonium hexafluorophosphate 0.3 g diethylene glycol dimethyl ether 13.7 g Next, as shown in FIG. 1A, after the chemical amplification resist 2 having the first material composition is dropped onto the semiconductor substrate 1 and spin-coated, The hot plate 6 was baked at a temperature of 90 ° C. for 1 minute to form a resist film 2 having a film thickness of 1.0 μm. Next, the resist film 2 was irradiated with KrF excimer laser light 4 through the mask 3.

Next, as shown in FIG. 1 (b), the resist film 2 was baked by a hot plate 6 at a temperature of 100 ° C. for 1 minute, and then, an organic alkaline aqueous solution (2.38% tetracarboxylic acid) was used. A resist pattern 2A was obtained by developing with a methyl ammonium hydroxide aqueous solution) for 1 minute.

Next, as shown in FIG. 1C, the resist pattern 2 is formed with the semiconductor substrate 1 kept at room temperature.
The t-butoxycarbonyl group was eliminated by irradiating A with radiation 5 having a wavelength of 200 to 600 nm as a main component of far-ultraviolet light at an output of 200 mW / cm ² for 3 seconds.

At this time, in order to control the temperature of the semiconductor substrate 1 to room temperature, a temperature controller using cooling water (trade name:
Coolnix) was used. The glass transition point of the resist pattern 2A thus obtained is about 180 ° C.
Therefore, even if the hot plate 6 is baked at a temperature of 160 ° C. for 10 minutes, the resist pattern 2A is not deteriorated, and the resist pattern 2A is formed on the semiconductor substrate 1 as shown in FIG. The transfer was accurate.

The size reduction amount of the 0.5 μm pattern after development and irradiation was 0.01 μm, which was a sufficiently small value.

Even if the chemically amplified resists having the following second to eighth material compositions shown below are used in place of the chemically amplified resist having the first material composition described above, it is completely Similar good results were obtained.

As described above, according to the first embodiment, a positive electrode containing a polymer compound or a monomolecular compound in which at least a part of the phenolic hydroxyl group is substituted with a protective group which is easily removed by the action of an acid as a main component. By using the mold resist as a deep-UV sensitive resist and irradiating the developed resist pattern with deep-UV light over the entire surface, a highly heat-resistant fine pattern could be accurately and easily formed with a small dimensional variation.

(Second Material Composition) Poly (p- (1-ethoxyethoxy) styrene-p-hydroxystyrene) (weight average molecular weight about 10,000, monomer unit ratio about 1: 1) 6.0 g 2-cyclohexylcarbonyl- 2- (p-toluenesulfonyl) propane 0.3 g Diethylene glycol dimethyl ether 13.7 g (third material composition) Poly p-vinylphenol (weight average molecular weight about 10,000) 5.0 g 2,2-bis (4-tetrahydropyranyl Oxyphenyl) propane 1.5 g 2-Cyclohexylcarbonyl-2- (p-toluenesulfonyl) propane 0.3 g Diethylene glycol diethyl ether 13.2 g (4th material composition) Poly (p-tert-butoxystyrene-p-hydroxystyrene) ) (Weight average molecular weight about 10,000, monomer unit ratio about 1: 1) 6.0 g Lohexyl sulfonyl diazomethane 0.3 g Diethylene glycol diethyl ether 13.7 g (fifth material composition) Poly p-vinylphenol (weight average molecular weight about 20,000) 5.0 g 3,4-dihydro-4- (2,4-di- (1-ethoxyethoxy) phenyl) -7- (1-ethoxyethoxy) -2,2,4-trimethyl-2H-1-benzopyran 1.5 g 2-cyclohexylcarbonyl-2- (p-toluenesulfonyl) propane 3 g Methyl 3-methoxypropionate 13.2 g (sixth material composition) Poly (p-tetrahydropyranyloxystyrene-p-hydroxystyrene) (weight average molecular weight about 10,000, monomer unit ratio about 3: 7) 6.0 g 2-Cyclohexylcarbonyl-2- (p-toluenesulfonyl) propane 0.3 g 2-heptanone 13.7 g (seventh material composition) poly (p- (1-methoxy-1-methylethyl) Xy) Styrene-p-hydroxystyrene) (weight average molecular weight about 10,000, monomer unit ratio about 1: 1) 6.0 g p-toluenesulfonic acid 2,6-dinitrobenzyl 0.1 g diethylene glycol dimethyl ether 13.9 g (eighth type) Material composition) m-cresol novolac resin 5.0 g p-terolahydropyranyloxystyrene (weight average molecular weight about 10,000) 0.6 g triphenylsulfonium hexafluorophosphate 0.1 g diethylene glycol dimethyl ether 14.3 g (second example) and below A fine pattern forming method according to the second embodiment of the present invention will be described.

First, a chemically amplified resist having the above-mentioned second material composition is dropped on a semiconductor substrate for spin coating, and then baked for 1 minute at 90 ° C. on a hot plate to form a film. Thickness 1.0
A μm resist film was formed. Next, the resist film was irradiated with an electron beam having an acceleration voltage of 50 keV.

Next, the resist film was baked at a temperature of 100 ° C. for 1 minute with a hot plate, and then developed with an organic alkali aqueous solution for 1 minute to obtain a resist pattern.

Next, with the temperature of the semiconductor substrate kept at 50 ° C., a wavelength of 200 to 40 is applied to the resist pattern.
The 1-ethoxyethyl group was eliminated by irradiating the whole surface with a radiation mainly composed of 0 nm deep ultraviolet rays for 0.7 seconds.

The glass transition point of the resist pattern thus obtained was about 180 ° C., and the resist pattern did not deteriorate even when baking was performed at a temperature of 160 ° C. with a hot plate.

The size reduction amount of the 0.5 μm pattern after development and irradiation was 0.02 μm, which was a sufficiently small value.

Even if a chemically amplified resist having the first and third to eighth material compositions is used in place of the chemically amplified resist having the second material composition, the above radiation irradiation method does not cause any problem. Similar good results were obtained.

As described above, according to the second embodiment, a positive electrode containing, as a main component, a polymer compound or a monomolecular compound in which at least a part of the phenolic hydroxyl group is substituted with a protecting group which is easily eliminated by the action of an acid. By using the mold resist as an electron beam resist and irradiating the developed resist pattern with far ultraviolet rays over the entire surface, a highly heat-resistant fine pattern could be formed accurately and easily with a small amount of dimensional variation.

In the second embodiment, electron beam exposure was used, but instead of this, X-rays were used, and similar effects were obtained.

(Third Embodiment) A fine pattern forming method according to a third embodiment of the present invention will be described below.

First, a chemically amplified resist of the fourth material composition was dropped on a semiconductor substrate for spin coating, and then baked for 1 minute at 90 ° C. on a hot plate to form a film thickness. 1.0 μm
Was formed. Next, the resist film was irradiated with KrF excimer laser light through a mask.

Next, the resist film was baked on a hot plate at a temperature of 100 ° C. for 1 minute, and then developed with an organic alkali aqueous solution for 1 minute to obtain a resist pattern.

Next, while maintaining the temperature of the semiconductor substrate at 100 ° C., a wavelength of 20 is applied to the above resist pattern.
Radiation consisting mainly of deep UV rays of 0 to 400 nm
The tert-butyl group was eliminated by irradiating the entire surface for 2 seconds.

Next, the undecomposed tert-butyl group was decomposed by baking on a hot plate at a temperature of 160 ° C. for 90 seconds.

The size reduction amount of the 0.5 μm pattern after development and after the heat treatment by baking was 0.02 μm, which was a sufficiently small value. Also, the shape of the resist pattern remained good.

Even if a chemically amplified resist having the first to third or fifth to eighth material compositions is used instead of the chemically amplified resist having the fourth material composition, the above radiation irradiation is performed. The method gave exactly the same good results.

As described above, according to the third embodiment, a positive electrode containing a high molecular compound or a monomolecular compound in which at least a part of the phenolic hydroxyl group is substituted with a protective group which is easily eliminated by the action of an acid. -Type resist is used as a far-ultraviolet sensitive resist, the temperature of the semiconductor substrate is kept below the glass transition point of the above chemically amplified resist and the whole far-ultraviolet ray is irradiated to the resist pattern after development, followed by heat treatment. Thus, a highly heat-resistant fine pattern could be formed accurately and easily with a small amount of dimensional variation.

The heat treatment is not particularly limited,
It is only necessary to be able to decompose the undecomposed protecting group.

Further, in the third embodiment, the exposure was carried out by the KrF excimer laser light, but the same good result was obtained by using the electron beam or the X-ray.

[0083]

According to the method of forming a fine pattern according to the first aspect of the present invention, the resist pattern is entirely irradiated with radiation while the temperature of the semiconductor substrate is kept below the glass transition point of the chemically amplified resist. Since it has a heat resistance imparting step of removing the protective group in the resist, it becomes difficult for the chemically amplified resist to cure, and it is difficult for the volume reduction of the resist pattern accompanying curing of the chemically amplified resist to occur. The amount of dimensional variation can be suppressed to the minimum.

Therefore, according to the first aspect of the invention, since the amount of dimensional variation is small, the pattern size can be accurately controlled, and a fine pattern having heat resistance sufficient to withstand dry etching under high temperature can be formed. become.

Further, according to the invention of claim 1, since heat treatment for hardening the resist pattern is not required, irradiation of high temperature and high power radiation is unnecessary,
Throughput can also be improved.

Therefore, by using the present invention, it is possible to easily form a highly accurate and highly heat-resistant fine resist pattern, which can greatly contribute to the manufacture of an ultrahigh-density integrated circuit.

According to the method of forming a fine pattern according to the second aspect of the present invention, by heating the semiconductor substrate after irradiating the resist pattern with the whole surface of the radiation, the protective groups which have not been eliminated by the whole irradiation of the radiation are completely eliminated. Therefore, the heat resistance of the chemically amplified resist is improved.

Therefore, according to the second aspect of the present invention, even when using the chemically amplified resist in which the protective group is hard to be removed by the whole surface irradiation with radiation, the pattern size can be accurately controlled and the dry etching is sufficiently performed at a high temperature. A fine pattern having heat resistance to withstand can be formed.

According to the fine pattern forming method of the third aspect of the present invention, since the semiconductor substrate is not baked in the heat resistance imparting step, the throughput is improved as compared with the case where baking is performed.

According to the fine pattern forming method of the fourth aspect of the present invention, since deep ultraviolet rays are used as the radiation in the heat resistance imparting step, the radiation can be handled easily and the elimination reaction of the protective group can be efficiently carried out. it can.

According to the fine pattern forming method of the fifth aspect of the present invention, since the energy amount of radiation in the heat resistance imparting step is 10,000 mJ / cm ² or less, the heat resistance of the resist pattern can be improved with a small energy amount. Therefore, the amount of dimensional variation of the resist pattern can be reliably suppressed.

According to the fine pattern forming method of the sixth aspect of the present invention, in the resist pattern forming step, the chemically amplified resist which has been exposed to or irradiated with radiation is heated. Since the acid generated in the above can be diffused, the chemically amplified resist can be more reliably developed.

[Brief description of drawings]

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

2 (a) and 2 (b) are views showing changes in infrared spectrum when a chemically amplified resist containing a polyvinylphenol derivative as a main component is irradiated with radioactivity, and FIG. It shows before irradiation of radiation, and (b) shows after irradiation of radiation.

3 (a) and 3 (b) are diagrams showing the dimensional variation of a 0.5 μm line-and-space pattern when a chemically amplified resist containing a polyvinylphenol derivative as a main component is used, (A) is based on the conventional method, and (b) is based on the method of the present invention.

4A and 4B are schematic views of a sectional shape of a 0.5 μm contact hole in the case where a chemically amplified resist containing a polyvinylphenol derivative as a main component is used, and FIG. Method of
(B) is based on the method of the present invention.

FIG. 5: 0.35 μm line formed by a chemically amplified resist whose main component is a polyvinylphenol derivative.
It is a figure which shows the dimensional change of a resist pattern when changing the temperature of a semiconductor substrate and performing far-ultraviolet irradiation to the resist pattern of space.

FIG. 6 is a cross-sectional view showing each step of a conventional fine pattern forming method.

FIG. 7 is a diagram showing a measured dimension after development and a measured dimension after heat treatment of a resist pattern formed by a conventional fine pattern forming method.

[Explanation of symbols]

 1 Semiconductor Silicon Substrate 2 Resist Film 2A Resist Pattern 3 Mask 4 Exposure Light 5 Radiation 6 Hot Plate 7 Far UV

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masako Sasako 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Inside the research institute (72) Inventor Keitoshi Fujie 1633 Matoba, Kawagoe City, Saitama Wako Pure Chemical Industries, Ltd.

Claims (6)

[Claims] 1. A chemistry comprising a radiation-sensitive material containing, as a main component, a polymer compound or a monomolecular compound in which at least a part of phenolic hydroxyl groups is substituted with a protecting group which is easily eliminated by the action of an acid on a semiconductor substrate. A resist coating step of applying an amplification type resist, and after exposing or irradiating the chemical amplification type resist, by developing the chemical amplification type resist, a resist pattern made of the chemical amplification type resist is formed. The resist pattern forming step of forming and the irradiation of the entire surface of the resist pattern with radiation while maintaining the temperature of the semiconductor substrate at the glass transition point of the chemically amplified resist or less is performed to remove the protective groups in the chemically amplified resist. And a heat resistance imparting step of improving the heat resistance of the resist pattern by separating. Micropattern forming method according to symptoms. 2. The heat resistance imparting step comprises heating the semiconductor substrate after irradiating the entire surface of the resist pattern with radiation in a state where the temperature of the semiconductor substrate is kept below the glass transition point of the chemically amplified resist. 2. The method for forming a fine pattern according to claim 1, which is a step of improving the heat resistance of the resist pattern. 3. The method for forming a fine pattern according to claim 1, wherein the entire surface irradiation with the radiation in the heat resistance imparting step is performed without baking the semiconductor substrate. 4. The fine pattern forming method according to claim 1, wherein the radiation in the heat resistance imparting step is deep ultraviolet rays. 5. The method for forming a fine pattern according to claim 1, wherein the energy amount of radiation in the heat resistance imparting step is 10,000 mJ / cm ² or less. 6. The resist pattern forming step is for diffusing the acid generated in the chemically amplified resist after the chemically amplified resist is exposed or irradiated with radiation. 6. The step of forming a resist pattern made of the chemically amplified resist by heating the chemically amplified resist, and then developing the chemically amplified resist, according to any one of claims 1 to 5, Fine pattern forming method.