JP2000089477A - Method of forming resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase strength of a resist pattern in a resist process using a chemically amplifying resist by carrying out a treatment with an aq. crosslinking agent soln. using a crosslinking agent after development and by heating the resist during the treatment so as to allow the thermal crosslinking agent to permeate through the resist pattern and to cause thermal crosslinking reaction in the resist, and therefore, to prevent falling or bending of the resist pattern due to surface tension of a rinsing liquid, and to form a good resist pattern. SOLUTION: In this resist pattern forming method by which a resist 11 is exposed and developed, then the developer 13 is removed and dried, the resist is treated with a crosslinking aq. soln. without rinsing after development, while heated during the treatment. By heating, the thermal crosslinking reaction is caused in the resist. In the method, the crosslinking agent is preferably hexamethylol melamine.

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 to a method for forming a resist pattern in which the resist pattern is prevented from falling down.

[0002]

2. Description of the Related Art With the recent high integration of semiconductor integrated circuits (LSIs), resist materials having high sensitivity, high resolution, and excellent dry etching resistance have been required. Currently, photoresists based on novolak resins, which are widely used, are difficult to use due to light transmittance problems as the exposure light source becomes shorter wavelength from i-ray (365 nm) to KrF excimer laser (248 nm). It has become. Therefore, a chemically amplified resist utilizing a catalytic reaction attracts attention, and its application to a process is being studied earnestly. In addition, the chemically amplified resist is promising as a resist material for lithography of not only far ultraviolet rays but also electron beams and X-rays.

A chemically amplified resist is composed of a base resin and an acid generator (PAG), and in the case of a three-component resist, contains a dissolution inhibitor, a crosslinking agent, and the like. Chemically amplified resist
A substance having a catalytic action (acid or base) is generated by a photochemical reaction, followed by a post-exposure bake (PEB:
This substance is reacted with a functional group or a functional substance in a polymer during post-exposure baking. A resist pattern is formed by utilizing a physical property reaction developed along with this reaction.

FIG. 5 shows a typical reaction example of a chemically amplified resist. As shown in FIG. 5A, the acid generated from the acid generator (PAG) by exposure acts as a catalyst,
Even after a reaction for eliminating one tertiary butoxycarbonyl (t-BOC: t-butoxycarbonyl) group shown in (b), the compound remains as an acid and can cause many reactions. The generated polyhydroxystyrene is dissolved in the alkaline developer, so that a positive resist pattern can be obtained.

[0005] The acid generation reaction causes only one reaction at most due to the action of one photon, but the t-BOC decomposition reaction causes one reaction.
One acid can contribute to many reactions, and is called a chemical amplification reaction. A conventional resist process using these resists is shown in FIGS. First, in order to make the surface of the semiconductor substrate 10 hydrophobic, a surface treatment is performed using a silane coupling agent such as hexamethyldisilazane (HMDS) having a high vapor pressure.

Next, a resist 11 is applied on the semiconductor substrate 10 by using a spin coating method. Since a large amount of solvent remains in the applied resist 11 and the free volume of the film is large and the density is poor, the dissolution rate in the developing solution is large and unstable. Therefore, the residual solvent in the resist 11 is volatilized by thermal energy, and at the same time, the adhesiveness to the semiconductor substrate 10 is increased, and pre-baking is performed after applying the resist 11 in order to further stabilize the resist characteristics.

Next, as shown in FIG. 3A, exposure is performed by an apparatus using exposure light 12 such as ultraviolet rays, electron beams or X-rays. Thereafter, heat energy is applied by a post-exposure bake (PEB) to cause a reaction using the acid generated in the resist 11 film by the exposure as a catalyst. This acid-catalyzed reaction is usually a crosslinking reaction if the resist 11 is negative type, and a decomposition reaction of the dissolution inhibiting part if the resist 11 is positive type.

Next, as shown in FIG. 3B, a developing solution 13 using an aqueous solution of an organic alkali such as tetramethylammonium hydroxide (TMAH) is placed on the semiconductor substrate 10 and development is performed while standing still. Accordingly, the resist pattern 11 can be formed by absorbing ultraviolet rays, X-rays, electron beams, and the like, and eluting unnecessary portions by utilizing the difference in the dissolution rate of the chemically changed resist 11 in the developing solution 13. .

A rinsing step (see FIG. 3 (c)) performed after the development has a role of washing the developing solution 13 in the resist 11 with the rinsing solution 14 and stopping the developing and dissolving reaction of the resist 11. The rinsing liquid 14 used here is usually pure water. Finally, the developing solution 13 and the rinsing solution 14 remaining in the resist 11 or on the surface are volatilized and removed to improve the resistance as an etching mask pattern and to enhance the adhesion to the interface with the underlying layer.
Post bake is performed between 00 ° C and 140 ° C.

However, recently, after the rinsing step, the fine pattern collapses or bends as shown in FIG. This phenomenon depends on the ratio between the height and the line width of the resist pattern 11, that is, the aspect ratio.
In the case of 0.2 μm line & space, the aspect ratio is 5
Exceeding the limit causes the resist pattern to collapse or bend. Further, when the pattern becomes finer, the resist pattern 11 may fall or bend even at a smaller aspect ratio. Further, pattern collapse occurs in any case without depending on the type of the resist 11 or the exposure method of lithography, and thus becomes a serious and urgent problem as the miniaturization progresses.

The cause of the falling or bending of the resist pattern 11 is as follows, as shown in FIG.
The rinsing liquid 14 remaining between 1 is generated because surface tension 17 is generated between the resist patterns 11 during rinsing drying.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of the prior art, and in particular, in a resist process using a chemically amplified resist, a treatment with an aqueous solution of a crosslinking agent using a crosslinking agent after development. By heating during the process, the thermal cross-linking agent penetrates into the resist pattern, causing a thermal cross-linking reaction in the resist, increasing the strength of the resist pattern, and preventing the resist pattern from falling or bending due to the surface tension of the rinsing liquid It is another object of the present invention to provide a novel resist pattern forming method for forming a good resist pattern.

[0013]

SUMMARY OF THE INVENTION The present invention basically employs the following technical configuration to achieve the above object. That is, a first aspect of the method of forming a resist pattern according to the present invention is a method of forming a resist pattern, which comprises exposing a resist, developing the resist, and rinsing and drying a developer. The cross-linking agent aqueous solution treatment is performed without performing the treatment, and heating is performed during the treatment. The second aspect is characterized in that the resist is thermally cross-linked by the heating. And
A third aspect is characterized in that the cross-linking material uses an epoxy compound, and a fourth aspect is that the cross-linking material uses hexamethylolmelamine. According to a fifth aspect, in a method for forming a resist pattern using a chemically amplified resist, a first step of developing the resist and a cross-linking without performing a rinsing treatment after development are performed. The method is characterized by including a second step of performing a material aqueous solution treatment and a third step of performing a rinsing treatment and drying.

In a sixth aspect, in the second step, the crosslinking material is heated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resist pattern forming method according to the present invention employs a cross-linking agent aqueous solution treatment using a cross-linking agent 15 in a resist process using a chemically amplified resist 11 without performing a rinsing process after development. The resist pattern forming method includes performing a heating process, performing a rinsing process, and finally drying.

1 and 2 show a method of forming a resist pattern according to the present invention. In the method of forming a resist pattern according to the present invention, a cross-linking agent 15 is penetrated into the resist pattern 11 and heated to cause a thermal cross-linking reaction in the resist 11 to increase the strength of the resist pattern 11.
Accordingly, it is possible to prevent the resist pattern 11 from falling down or bending due to the surface tension 17 of the rinse liquid 14 generated at the time of rinsing drying, and to form a good resist pattern 11. Further, the resist pattern 11 having a high aspect ratio can be formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific example of a method for forming a resist pattern according to the present invention will be described in detail with reference to the drawings. (First Specific Example) FIGS. 1A and 1B show the structure of a specific example of a method for forming a resist pattern according to the present invention.
In the method for forming a resist pattern in which the developing solution 13 is rinsed and dried after development, a method for forming a resist pattern in which a cross-linking agent aqueous solution treatment is performed without performing the rinsing treatment after the development and heating is performed during the treatment is shown. I have.

Hereinafter, the present invention will be described in more detail. First, in order to make the surface of the semiconductor substrate 10 hydrophobic, a surface treatment is performed with a silane coupling agent such as hexamethyldisilazane (HMDS) having a high vapor pressure. Next, the resist 11 is applied on the semiconductor substrate 10 using a spin coating method. Since a large amount of solvent remains in the applied resist 11 and the free volume of the film is large and the density is poor, the dissolution rate in the developing solution is large and unstable. For this reason, the residual solvent in the resist 11 is volatilized by thermal energy, and at the same time, the semiconductor substrate 10
In order to increase the adhesion to the resist and stabilize the resist characteristics, pre-baking is performed at 90 ° C. to 110 ° C. after applying the resist.

Next, as shown in FIG. 1A, exposure is performed by an apparatus using exposure light 12 such as ultraviolet rays, electron beams or X-rays. Thereafter, by performing post-exposure bake (PEB) at a temperature between 90 ° C. and 120 ° C., thermal energy is applied to cause a reaction using an acid generated in the resist 11 film by the exposure as a catalyst. Next, as shown in FIG. 1 (b), a developer 1 containing 2.38 wt% of an organic alkali aqueous solution such as tetramethylammonium hydroxide (TMAH) was used.
3 is placed on the semiconductor substrate 10 and is developed for 60 to 120 seconds while standing still. As a result, the developing solution 13 of the resist 11 which has absorbed ultraviolet rays, X-rays,
Unnecessary portions are eluted by utilizing the difference in dissolution rate of the resist pattern 11 to form a resist pattern 11.

Next, as shown in FIG. 1C, an aqueous solution 16 of a crosslinking agent using an epoxy compound as the crosslinking agent 15 is placed on the semiconductor substrate 10 without performing a rinsing process.
While keeping still for 0 second or more, heat treatment is performed at 70 ° C. to 90 ° C. or more at the same time. As a result, the cross-linking agent 15 penetrates into the resist 11 and gives heat energy to the resist 11.
A thermal cross-linking reaction takes place therein, whereby the base resin in the resist 11 is cross-linked to increase the strength of the resist pattern 11.

Thereafter, as shown in FIG. 2A, the cross-linking agent aqueous solution 1 in the resist 11 is rinsed with a rinsing solution 14 using pure water.
6 is washed and dried. Then, as shown in FIG. 2B, the strength of the resist pattern 11 is increased even if the surface tension 17 of the rinse liquid 14 remaining between the resist patterns 11 is generated during the rinsing drying. No falling or bending will occur.

Finally, the developing solution 13 and the rinsing solution 14 remaining in or on the resist 11 are volatilized and removed.
Post-baking is performed at 100 ° C. to 140 ° C. in order to improve the resistance as an etching mask pattern, enhance the adhesion to the interface with the base, and the like. As a result, a good resist pattern 11 is obtained as shown in FIG. Further, a resist pattern 11 having a high aspect ratio can be obtained in the same manner.

(Second Specific Example) Next, a second specific example of the present invention will be described. First, similarly to the first specific example, surface treatment of the semiconductor substrate 10, application of the resist 11,
After pre-baking, exposure and development are performed to form a resist pattern 11.

Next, an aqueous solution 16 of a cross-linking agent using hexamethylol melamine as the cross-linking agent 15 is placed on the semiconductor substrate 11, kept still for 120 seconds or more, and simultaneously heat-treated at 130 ° C. or more. Thereby, similarly to the above specific example, the cross-linking agent 15 soaks into the resist 11, and a thermal cross-linking reaction occurs in the resist 11 by applying thermal energy,
The strength of the resist pattern 11 can be increased by crosslinking the base resin in the resist 11.

Thereafter, the rinsing liquid 14 is treated and dried, and finally post-baking is performed, whereby a good resist pattern 11 is obtained as in the above-described specific example. Also, a resist pattern 11 having a high aspect ratio can be obtained.

[0026]

According to the method for forming a resist pattern according to the present invention, a cross-linking agent solution treatment is carried out without performing a rinsing treatment after development, and the cross-linking agent is permeated into the resist by heating during the treatment, whereby a thermal crosslinking reaction is performed. , The strength of the resist pattern using the chemically amplified resist can be increased, and as a result, the resist pattern does not collapse or bend.

Further, a resist pattern having a high aspect ratio can be formed.

[Brief description of the drawings]

FIGS. 1A to 1C are cross-sectional views in each step for explaining a resist pattern forming method using a chemically amplified resist of the present invention.

FIG. 2 is a sectional view in each step following FIG. 1;

FIG. 3 is a cross-sectional view for explaining a conventional method of forming a resist pattern.

FIG. 4 is a sectional view in each step following FIG. 3;

FIG. 5 is a diagram for explaining a reaction mechanism of a typical positive chemically amplified resist.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Semiconductor substrate 11 Resist (chemical amplification type resist) and resist pattern 12 Exposure light 13 Developing solution 14 Rinse solution 15 Crosslinking agent 16 Crosslinking agent aqueous solution 17 Surface tension

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H025 AA01 AA02 AA03 AB16 AC04 AC05 AC06 AD03 BG00 CC17 EA01 EA05 FA01 FA09 FA16 FA29 FA31 2H096 AA25 BA11 CA02 CA14 DA01 EA03 EA06 EA07 GA09 HA01 JA01 5F046 AA05 KA01 LA01

Claims (6)

[Claims] 1. A method of forming a resist pattern, comprising: exposing a resist, developing the resist, rinsing and drying a developer, and performing an aqueous solution of a cross-linking material without performing a rinsing process after the development. A method for forming a resist pattern, comprising heating. 2. The method according to claim 1, wherein the heating causes a thermal crosslinking reaction in the resist. 3. The method for forming a resist pattern according to claim 1, wherein the cross-linking material uses an epoxy compound. 4. The cross-linking material according to claim 1, wherein hexamethylol melamine is used.
A method for forming a resist pattern as described above. 5. A method of forming a resist pattern using a chemically amplified resist, comprising: a first step of developing the resist; and a second step of performing an aqueous solution of a cross-linking material without performing a rinsing process after the development. A third step of performing a rinsing process and drying, and a method of forming a resist pattern. 6. The method according to claim 5, wherein in the second step, a cross-linking material is heated.