JPS6214146A - Radiosensitive resist material and fine working method using said material - Google Patents

Abstract

PURPOSE:To improve the resolution and the dryetching resisting property of the titled material by incorporating the radiosensitive resist material composed of a polymer contg. a specific repeating unit to the radiosensitive material. CONSTITUTION:The polymer having the structure shown by the formula, namely the polymer contg. an aromatic ring having a carbonyl compd. preferably the polymer contg. the aromatic ring having the carbonyl compd. substd. with a halogen atom, has a high sensitivity for a radiation ray, especially, an electron beam and a X ray, thereby enabling to give the good anti-dryetching property. The compd. shown by the formula comprises for example, a homopolymer comprising an acetylstyrene, a chloroacetylstyrene, a bromoacetylstyrene, a dichloroacetylstyrene, a trichloroacetylstyrene, a trichloroacetylstyrene, an acetyl-alpha-methylstyrene, a chloroacetyl-alpha-methylstyrene, a bromoacetyl-alpha- methylstyrene and a trichloroacetyl-alpha-methylstyrene and a copolymer contg. the prescribed compd. as one of the repeating units.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radiation-sensitive resist material useful in manufacturing semiconductor integrated circuits and the like, and a microfabrication method using the same.

[Background of the invention]

Conventionally, a method of forming patterns using photosensitive resin (photoresist) that is sensitive to visible light and ultraviolet light has been widely used in the etching process in the manufacture of semiconductor integrated circuits, magnetic bubble memo IJ-2 devices, etc. (although it has not been put into practical use yet). In recent years, in order to improve the performance and reliability of integrated circuits, there has been an increasing demand for higher density elements, and vigorous research is underway to establish ultra-fine circuit pattern technology. Among these, methods of forming highly accurate circuit patterns using high-energy radiation such as deep ultraviolet rays with short wavelengths, X-rays, and electron beams in place of conventional light beams are being put into practical use.

Along with this, it has become necessary to develop high-performance resist materials that are sensitive to these radiations.

When manufacturing integrated circuits, a method is used in which a resist material is applied onto a substrate to form a thin film, a pattern is formed by exposing and developing radiation, and then the substrate is etched using the pattern as an etching mask. ing. In such an integrated circuit manufacturing process, high sensitivity and high resolution are important performances required of the resist. Regarding sensitivity, for example, 10 for electron beams.
-'C/a+f level and 10mff/i for X-rays
High sensitivity is required. Also, regarding resolution, 1
There is a strong demand for resists that can be used for fine processing of microns or even submicrons. Furthermore, in the etching process, conventional wet etching methods using chemicals have been used, but they are not suitable due to the side etching phenomenon, and gas plasma is used for submicron microfabrication.

There is a shift to dry etching using reactive sputtering. Therefore, materials that have excellent resistance to dry etching are required as resists.

To date, several radiation-sensitive resists for microfabrication have been developed, but very few of them satisfy all of the above-mentioned required performances. Chloromethylated polystyrene (cMs), which was developed as a negative resist, has excellent resolution and dry etching resistance, and has been put into practical use for forming fine circuit patterns, but its sensitivity is still insufficient. What is difficult is that the practical sensitivity for electron beams is 10'''C1ca, but for X-rays it is 100mJ/c!!
This is because it is not practical because it is both before and after. Therefore, it has been desired to develop a resist that is even more sensitive than CMS.

[Purpose of the invention]

It is an object of the present invention to solve the above-mentioned problems seen in conventional resists and to use high-energy radiation, particularly electron beams,
It is an object of the present invention to provide a negative radiation-sensitive resist material having high sensitivity to radiation, good resolution, and excellent dry etching resistance, and a microfabrication method using the same.

[Structure of the invention]

That is, the radiation-sensitive resist material of the present invention has the following general formula [I]: OX.

(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and XIs x! and X represent a hydrogen atom or). Furthermore, the microfabrication method of the present invention is characterized in that the microfabrication method comprises forming a thin film of a radiation-sensitive material on a substrate, irradiating it with radiation, developing and etching it. The present invention is characterized in that a radiation-sensitive resist material, which is a polymer containing a repeating unit represented by the above general formula [11], is used as the radiation-sensitive material.

The purpose of the present invention is to obtain a resist material that imparts good dry etching resistance and is highly reactive to radiation by containing an aromatic ring in the repeating unit structure of a polymer. As a result of extensive research, we have found that the structure represented by the above general formula [I], that is, the structure in which the aromatic ring is substituted with a carbonyl compound, preferably a carbonyl compound containing no-rogen, is resistant to radiation, especially electron beams, It was discovered that it has high sensitivity to X-rays.

Specific examples of compounds represented by the general formula [l] (doacetylstyrene, chloroacetylstyrene, bromoacetylstyrene, dichloroacetylstyrene, trichloroacetylstyrene, acetyl α-methylstyrene, chloroacetyl α-methylstyrene, bromoacetylstyrene, Acetyl α-
Examples include homopolymers such as methylstyrene and trichloroacetyl α-methylstyrene, and copolymers containing these as one component repeating unit. Copolymer components are not particularly limited, but include, for example, heterocyclic compounds such as vinylpyridine, aromatic vinyl compounds such as styrene, α-methylstyrene, vinylnaphthalene, etc.
Examples include methacrylic esters such as glycidyl methacrylate and methyl methacrylate, and acrylic esters such as ethyl acrylate. In these copolymers, the content of the repeating unit compound represented by the general formula [1] is 5% or more, preferably 10% or more.

These homopolymers or copolymers can be produced by a normal radical polymerization method.

The polymer of the present invention can also be easily produced by the method described below. That is, the general formula is -C)(, -C
! -,,, (■) (wherein, R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms)
After obtaining a polymer containing a repeating unit represented by f), a polymer containing a repeating unit represented by general formula [I] is obtained by introducing a substituent into an aromatic ring through a chemical reaction. can be obtained. Examples of polymers obtained by this method include Acetyl [Co., Ltd.] polystyrene, chloroacetyl polystyrene, bromoacetyl polystyrene, dichloroacetyl polystyrene, trichloroacetyl polystyrene, acetyl poly-α-methylstyrene, chloroacetyl poly-α-methylstyrene, and bromoacetyl polystyrene. Examples include polyα-methylstyrene, trichloroacetyl polyα-methylstyrene, and the like. The introduction ratio of substituents to nine aromatic terms is desirably 5 or more, preferably 10 or more.

The polymer containing the repeating unit represented by the formula [ll] can be produced by radical polymerization, cationic polymerization, or anionic polymerization, but considering that the resolution of the resist depends on the molecular weight distribution, It is preferable to obtain a polymer with a narrow molecular weight distribution by an anionic polymerization method.

Although it is not necessary to particularly limit the molecular weight of the polymer of the present invention, considering that the sensitivity of a resist made of the polymer depends on the molecular weight, it is desirable that the molecular weight is 10,000 or more, preferably 2QOOO or more.

In the present invention, the thus obtained polymer is dissolved in a solvent such as badruene, xylene, chlorobenzene, or ethyl cellosolve acetate, and then filtered through a microfilter to prepare a resist solution and subjected to a microfabrication process. The resist solution is applied onto a substrate by a spin coating method to form a uniform resist thin film, exposed to radiation such as electron beams or X-rays, and then developed to obtain a resist image. Thereafter, using the resist image as a mask, the substrate can be etched, preferably dry etched, to perform fine processing. Here, as a 1M source, palladium,
X-ray sources that use electron beams to excite silicon, c1dium, molybdenum, etc. as targets are in practical use.
There is no need to specifically limit the radiation source used in the microfabrication method of the present invention.

C Examples of the Present Invention] The resist material of the present invention, its manufacturing method, and the microfabrication method using the same will be described in more detail below with reference to Examples.

Example 1 20F polystyrene with a narrow molecular weight distribution (molecular weight 1.1 x 10') obtained by anionic polymerization was treated with 1000% carbon disulfide.
32 parts of aluminum chloride and 0 parts of monochloroacetic acid were added to the mixture, and the mixture was reacted for 24 hours with stirring at a temperature of 0°C. The reaction mixture was precipitated into methanol containing the antioxidant BIT to recover the reaction product, chloroacetyl polystyrene. The chloroacetylation rate was calculated to be 60% from the chlorine content of the product. Also, G
From the results of PC measurement, the degree of molecular weight dispersion (Mw/M
The value of n) was 1.1 or less, which was almost the same as the value of polystyrene used as a raw material. The reaction product was dissolved in xylene to make a solution with a concentration of 10 μm, and filtered through a microfilter with a pore size of 122 μm to prepare a resist solution. The resist solution was coated onto a silicon wafer by spin coating at 200 rpm using a spinner to form a uniform solution with a thickness of α65 μm. A resist thin film was formed.This was mixed with Orosolp in a mixed solvent (volume ratio 1:1).
It was immersed in water for 1 minute, rinsed with impropat tool, and dried. From the film thickness measurement of the formed pattern, the sensitivity, that is, the irradiation dose Dg corresponding to the gel point is 3x1o-c/
It was i. Further, as a result of examining the resolution of line/space patterns of different sizes, a resolution of I15μ was obtained.

Example 2 The X-ray irradiation characteristics of the resist material of Example 1 were investigated.

A silicon wafer/coated resist obtained using the same method as in Example 1 was irradiated with electron beam excitation characteristic X-rays (eL length 4.6X) targeting rhodium, and a pattern was formed using the same developing method as in Example 1. was formed and the sensitivity was evaluated. The result D
g was 20 mJ/Crl1.

Comparative Example Chloromethyl polystyrene (Toyo Soda type CMS-KX (
S)) was applied to a thickness of 165μ on a silicon wafer, and
After heat treatment at 20°C for 125 minutes, electron beam drawing and
It was subjected to radiation irradiation. The electron beam drawing device and the X-ray irradiation device were the same as those used in Examples 1 and 2, respectively.

After electron beam or X-ray irradiation, the film was developed by immersing it in a mixed solvent of isoamyl acetate and ethyl cellosolve (volume ratio 55:65) for 1 minute, rinsing with isopropanol, and drying.

From the film thickness measurement results, the sensitivity Dg is 1 for electron beams,
OX 1 (1'07di and 90 for X-rays
It was mJ/d.

These results demonstrate that the chloroacetyl polystyrene obtained in Example 1 of the present invention has high sensitivity compared to CMS.

Example 3 Chloroacetyl polystyrene was obtained in the same manner as in Example 1, except that the molecular weight of polystyrene with a narrow molecular weight distribution, which was the starting material for the reaction, was 55×10'. The substitution rate (chloroacetylation rate) was 52.

The dispersion degree Mw7'MnO value was 1.2. The reaction product was dissolved in xylene to form a 70% solution, and the sensitivity to X-rays was evaluated in the same manner as in Example 2. As a result, the value of Dg was 6 mJ/(i, and it was confirmed that the resist had a high sensitivity sufficient for practical use.

Example 4 Trichloroacetylpolystyrene was obtained by carrying out a reaction under substantially the same conditions as in Example 1, except that monoacetate chloride was triacetate chloride and the reaction temperature was 115°C. The substitution rate was 14%, and the value of the degree of dispersion My/Mn was 1.1 or less. As a result of evaluating the sensitivity in X-ray irradiation using the apparatus of Example 2 using a 10% xylene solution as in Example 1, Dgl was 4 om.
J/ci and CM of similar molecular weight and substitution rate,
(CMS-DU manufactured by Toyogatatsu), the sensitivity was about 4 times higher.

Example 5 Radical polymerization was carried out in trichloroacetylstyrene and a styrene-free solvent using azobisisobutyronitrile as a catalyst to obtain a copolymer. The molecular weight of the copolymer is 1
．． 8×10', and the molar fraction of trichloroacetylstyrene units in the copolymer was 40. Example 1
As a result of examining the electron beam drawing characteristics in the same manner as in Example 1, the resolution was α8μ, which was slightly inferior to Example 1, but the sensitivity was 2.5-X 10-7C/crA as a Dgl value, which was high sensitivity as in Example 1. I confirmed that it was a resist.

Example 6 The etching resistance of the chloroacetylstyrene prepared in Example 1 was examined using a parallel plate dry etching apparatus. The etching rate for reactive sputtering using carbon tetrafluoride was measured at a high frequency power of 350 W. While the etching rate of silicon oxide is 1400 A/min, the etching rate of this resist material is 600 A/min.
It is clear that the etching rate is 2 or less, and that it has extremely high dry etching resistance.

〔Effect of the invention〕

As explained above, the resist material of the present invention has high sensitivity,
It has excellent resolution and dry etching resistance, and is particularly sensitive to electron beams and This is something that can be seen to be effective. That is, a high-resolution resist pattern of 1 micron or less can be formed in a short time using radiation such as electron beams or X-rays, and the substrate can be processed by dry etching, which is a remarkable effect.

Claims (3)

[Claims] (1) The following general formula [I]: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... [I] (In the formula, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, X_1, X_2, and X_3 represents a hydrogen atom or a halogen atom. (2) After forming a thin film of radiation-sensitive material on the substrate,
In a microfabrication method comprising irradiating with radiation and performing development and etching treatment, a radiation-sensitive resist material that is a polymer containing a repeating unit represented by the general formula [I] is used as the radiation-sensitive material. A microfabrication method characterized by (3) The microfabrication method according to claim 2, wherein the radiation is an electron beam or an X-ray.