JPH11153872A - Forming method of resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a resist pattern of high dimensional accuracy and good shape free from trailing or biting in a simple process. SOLUTION: A photoresist film 14 of a chemically intensified photoresist is formed on a semiconductor substrate 11 and exposed to UV rays or far-UV rays through a mask with a desired pattern of semiconductor integrated circuit, then backed and developed with an alkali developer. In this forming method of a resist pattern, before the photoresist film 14 is formed, an extremely thin layer 13 to which a large amt. of a photoacid generating agent is adsorbed is formed on the semiconductor substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a technique for manufacturing a semiconductor device, and more particularly to a method for forming a fine resist pattern.

[0002]

2. Description of the Related Art A conventional photolithography technique uses g-rays (436 nm) and i-rays (365 nm) as its exposure light. Dissolution-suppressing positive resists using quinonediazide were the mainstream.

[0005] However, lithography using excimer laser light (248 nm, 193 nm, etc.), which is far ultraviolet light that is advantageous for further miniaturization, is required. It was too large, a good resist pattern could not be obtained, and the sensitivity was greatly reduced.

However, a photoacid generator (PAG; Photo)
A chemically amplified yarn resist using a sensitization reaction of an acid catalyst generated from an acid generator (Ito et al., 1982 Symposium).
on VLSI Technology), a resist for short wavelength lithography, and a resist for electron beam lithography requiring high sensitivity.

[0005] In the case of a positive resist, this chemically amplified resist comprises a resin into which a dissolution inhibiting group is introduced and PAG. When this positive resist is exposed to light, an acid is generated from the PAG in the exposed portion, and the acid acts as a catalyst on the dissolution inhibiting group by exposure to light, causing the dissolution inhibiting group to be eliminated. As a result, the exposed portion becomes alkali-soluble, so that a positive pattern is formed.

On the other hand, a negative resist is composed of a resin, a crosslinking agent, and a PAG. When this chemically amplified negative resist is exposed, an acid is generated from the PAG in the exposed portion, and the acid generated by the post-exposure bake acts as a catalyst on the cross-linking agent to cause cross-linking of the resin. As a result, the exposed portion becomes hardly soluble in alkali, so that a negative pattern is formed.

However, since a pattern is formed using a small amount of acid in a chemically amplified resist, there is a large dependency on the surrounding environment, and there is a problem that a pattern abnormality occurs at an interface between the resist and the base substrate. This is a phenomenon that occurs when the acid generated in the resist diffuses into the underlying substrate or is deactivated by water or a basic substance present on the surface of the underlying substrate. In the case of a negative resist, the pattern appears as biting and falling (see FIG. 3).

In FIG. 3, reference numeral 31 denotes a semiconductor substrate, and 32 denotes a BPSG (Boro Phospho Si).
(License Glass) film, 34 denotes a chemically amplified resist film, and 35 denotes a resist pattern.

As a countermeasure, a method of sputter-forming an acid-inactive silicon film on the surface of an underlying substrate (Japanese Patent Laid-Open No. 3-2)
No. 49658) has been proposed, but this method is effective, but has a problem that the process becomes very complicated, such as the necessity of etching and removing the silicon film.

On the other hand, as a method for preventing a pattern abnormality by a simple method, there has been proposed a method of performing an acid treatment on a base surface (JP-A-5-341536).

[0011]

However, a method of supplying an acid to the surface of an underlying substrate by an acid treatment (Japanese Unexamined Patent Publication No. Hei 5-3415)
In 36), there is a problem that it is difficult to control the amount of acid supply, and the pattern abnormalities may be worse.
This is because the acid is similarly supplied to both the exposed portion and the end exposed portion, so that the contrast of the acid in the exposed portion and the unexposed portion formed by exposure is broken, and high-precision selective development becomes impossible. It is.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above points, and has as its object to form a resist pattern having a good shape and high dimensional accuracy without footing or biting by a simple process. .

[0013]

In order to solve the above-mentioned problems, the present invention forms a chemically amplified photoresist film on a semiconductor substrate, and passes ultraviolet or far ultraviolet light through a mask on which a desired semiconductor integrated circuit pattern is drawn. Irradiate,
In a method of forming a resist pattern in which development is performed using an alkaline developer after post-exposure bake, an extremely thin acid generating layer having a large amount of a photo acid generator adsorbed thereon is formed on a semiconductor substrate prior to forming a photoresist film. The method is adopted.
In that case, the acid generating layer can be formed by spin coating. In addition, BPSG (Boro P
(Hospho Silicate Glass) film may be formed, and an acid generating layer may be formed thereon. The acid generating layer can also be formed by spin-coating a solution of triphenylsulfonium in methyl ethyl ketone on a BPSG film. Further, in the present invention, a chemically amplified photoresist film is formed on a semiconductor substrate, and is irradiated with ultraviolet light or far ultraviolet light through a mask on which a desired semiconductor integrated circuit pattern is drawn. In a method of forming a resist pattern using a developing method, a method of forming a resin layer containing a large amount of a photoacid generator on a semiconductor substrate prior to forming a photoresist film was employed. In that case, the resin layer can be formed by spin coating. Also, BPSG on a semiconductor substrate
(Boro Phospho Silicate Gl
ass) A film may be formed, and a resin layer may be formed thereon. Alternatively, the resin layer can be formed by diluting a chemically amplified positive resist with the solvent and dissolving triphenylsulfonium on the BPSG film by spin coating.

According to the present invention, a large amount of acid is generated at the exposed portion at the resist-substrate interface, and it is possible to compensate for a decrease in acid concentration due to acid diffusion into the substrate and acid deactivation on the substrate surface. On the other hand, at the unexposed portion of the resist-substrate interface,
Since no acid is generated, high-precision selective development of exposed portions and unexposed portions becomes possible, and a favorable pattern without footing or digging can be formed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 (a) to (d)
FIGS. 2A to 2D are process diagrams illustrating a method for forming a resist pattern according to the first and second embodiments of the present invention.

(Embodiment 1) In a method for forming a resist pattern according to the present embodiment, an ultra-thin layer 13 containing a large amount of an acid generator is formed on a base substrate 1 before forming a chemically amplified photoresist film 14. It is characterized in that it is formed.

That is, first, on the silicon substrate 11,
BPSG (BoroPhospho Si) having a thickness of 1 μm
(Liquid Glass) film 12 is formed by a CVD method (FIG. 1A).

Subsequently, 1% by weight of the acid generator triphenylsulfonium triflate is dissolved in methyl ethyl ketone and spin-coated on the BPSG film 12 to form an extremely thin layer (acid generating layer) 13 of the acid generator. (FIG. 1b).

Thereafter, the chemically amplified negative resist film 14 is used.
Is formed by spin coating and baking before exposure (FIG. 1)
c).

Next, pattern exposure through a mask is performed by a KrF excimer laser stepper, and after exposure baking, development is performed with a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH).

As a result, a negative resist pattern 15 having a vertical side wall shape without biting was obtained (FIG. 1D).

On the other hand, when the negative resist film 14 was formed directly on the BPSG film 12, remarkable digging was observed at the bottom of the pattern, and collapse was observed with a fine pattern of 0.30 μm or less.

(Embodiment 2) FIGS. 2 (a) to 2 (d)
FIG. 8 is a view showing a process chart of the resist pattern forming method according to the second embodiment of the present invention;

In this embodiment, a 1 μm-thick BPSG (BoroPhospho) is formed on a silicon substrate 21.
(Silicate Glass) film 22 is formed by a CVD method (FIG. 2A).

Subsequently, the chemically amplified positive resist used in this example was diluted 10-fold with the solvent, and triphenylsulfonium triflate was dissolved at 5% by weight to obtain BPS.
Spin coating is performed on the G film 12, followed by pre-exposure baking to form an extremely thin layer (resin layer) 23 containing a large amount of an acid generator (FIG. 2B).

Thereafter, a positive resist film 14 is spin-coated and formed by baking before exposure (FIG. 2C).

Next, pattern exposure is performed through a mask using a KrF excimer laser stepper, and after exposure baking, development is performed with a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH).

As a result, a positive resist pattern 25 having a vertical side wall shape without footing was obtained (FIG. 2D).

[0029]

As described above, according to the method of the present invention, it is possible to eliminate the pattern abnormality at the resist substrate interface, which is observed in the chemically amplified yarn resist pattern, and to obtain a finely shaped fine pattern of 0.30 μm or less. A resist pattern can be obtained. Further, the resolution, the depth of focus, and the dimensional accuracy can be significantly improved (10% or more).

[Brief description of the drawings]

FIG. 1 is a process diagram illustrating a method for forming a resist pattern according to a first embodiment of the present invention.

FIG. 2 is a process diagram illustrating a method for forming a resist pattern according to a second embodiment of the present invention.

FIG. 3 is a process diagram illustrating a conventional method for forming a resist pattern.

[Description of sign]

 11, 21, 31 Silicon substrate (semiconductor substrate) 12, 22, 32 BPSG film 13, Layer adsorbing a large amount of photoacid generator (acid generating layer) 23 Layer containing a large amount of photoacid generator (resin layer) 14, 24, 34 Chemical amplification resist film 15, 25, 35 Resist pattern

Claims (8)

[Claims] 1. A chemical amplification type photoresist film is formed on a semiconductor substrate, irradiated with ultraviolet rays or far ultraviolet rays through a mask on which a desired semiconductor integrated circuit pattern is drawn. A resist pattern forming method in which a very thin acid generating layer having a large amount of a photo acid generator adsorbed thereon is formed on a semiconductor substrate prior to forming a photoresist film. 2. The method according to claim 1, wherein the acid generating layer is formed by spin coating. 3. A BPSG (Boro) is formed on the semiconductor substrate.
3. The method according to claim 1, further comprising forming a PhosphoSilicate Glass film, and forming the acid generating layer thereon. 4. The acid generating layer is formed by dissolving triphenylsulfonium in methyl ethyl ketone by BPSG.
4. The method for forming a resist pattern according to claim 1, wherein the resist pattern is formed by spin coating on the film. 5. A chemically amplified photoresist film is formed on a semiconductor substrate, irradiated with ultraviolet light or far ultraviolet light through a mask on which a desired semiconductor integrated circuit pattern is drawn, and baked after exposure, and then using an alkali developing solution. Forming a resin layer containing a large amount of a photoacid generator on a semiconductor substrate prior to forming a photoresist film. 6. The method according to claim 5, wherein the resin layer is formed by spin coating. 7. A BPSG (Boro) is formed on the semiconductor substrate.
7. The method for forming a resist pattern according to claim 5, wherein a PhosphoSilicate Glass) film is formed, and the resin layer is formed thereon. 8. The resin layer is formed by diluting a chemically amplified positive resist with a solvent thereof and dissolving triphenylsulfonium on a BPSG film by spin coating. The method for forming a resist pattern according to any one of claims 5 to 7.