JPS6374049A - Radiation sensitive resist material and formation of pattern - Google Patents

Abstract

PURPOSE:To improve sensitivity to high energy radiation, more specifically electron rays and X-rays, definition and dry etching resistance by using a spe cific polymer contg. the repeating unit of the structure in which a naphthalene ring is substd. with a carbonyl compd. CONSTITUTION:The polymer contg. the repeating unit expressed by the formula I is used as a radiation sensitive material. In the formula I, a R denotes a hydrogen atom, alkyl group of 1-3C, X1-X3 denote a hydrogen atom or halogen atom. Such polymer is dissolved in a solvent to prepare a resist soln., which is then coated on a substrate by a spin coating method to form a uniform thin resist film. The film is exposed with the radiation such as electron rays of X-rays and is developed to form the resist image. The substrate is etched with said image as a mask to form the pattern.

Description

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

[Conventional technology] Conventionally, a method of forming patterns using photosensitive resin (photoresist) that is sensitive to visible light and ultraviolet light has been widely put into practical use in the etching process in the manufacture of semiconductor integrated circuits, magnetic bubble memory devices, etc. has been done. 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 intensive research is being carried out with the aim of establishing ultra-fine circuit pattern technology. Among these, methods of forming highly accurate circuit patterns using short-wavelength high-energy radiation such as deep ultraviolet rays, XSI, and electron beams instead 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 resist material is applied onto the substrate and 7! A method has been adopted in which a pattern is formed by forming a G film, exposing it to radiation, and developing it, and then etching the substrate using the pattern as an etching mask. In such an integrated circuit manufacturing process, high sensitivity and high resolution are important performances required of a nodist. For example, the sensitivity is on the order of 10-60/cm for electron beams or 10 m for X-rays.
High sensitivity on the order of J/ci is required. In addition, with regard to resolution, there is a strong demand for a resist that can be used for microfabrication of 1 micron or less. Furthermore, for etching culms, conventional wet etching methods using chemicals have been used.
Gas plasma is not suitable for submicron microfabrication because of the side etching phenomenon.

There is a shift to dry etching using reactive sputtering. Therefore, a material having excellent resistance to dry etching is required as a resist.

To date, several late OA ray-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 is used in practical applications for forming fine circuit patterns, but its sensitivity is still insufficient. The reason it is difficult is to reach practical sensitivity of 10'C/CIi for electron beams, but 100 m j / for X-rays.
This is because it is around ci and is therefore impractical. Therefore, it has been desired to develop a resist that is even more sensitive than CMS.

[Problem to be Solved by the Invention 1] An object of the present invention is to solve the above-mentioned problems seen in conventional resists, and to prevent high-energy radiation, particularly electron beams,
An object of the present invention is to provide a negative radiation-sensitive resist material having high sensitivity to radiation, good resolution, and excellent dry etching resistance, and a pattern forming method using the same.

[Means for Solving the Problems] That is, the radiation-sensitive resist material of the present invention has the following general formula [■]: -CH, -(1!-...[l] OX.

(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X, X and X3 represent a hydrogen atom or a halogen atom.) It is characterized by Further, the pattern forming method of the present invention includes forming a thin film of a material sensitive to radiation CJJ radiation on a substrate, and then irradiating it with radiation radiation and performing development and etching. The present invention is characterized in that a radiation-sensitive resist material, which is a polymer containing a repeating center represented by the above general formula [I], is used as the magnetic material.

The purpose of the present invention is to impart good dry etching resistance by incorporating naphthalene rings into the repeating unit structure of the polymer, and at the same time to provide resist materials with high radiation reactivity. and
As a result of extensive research, we found that the structure represented by the above general formula [I], that is, the structure in which the naphthalene ring is substituted with a carbonyl compound, preferably a halogen-containing carbonyl compound, has a high resistance to radiation, especially electron beams and X-rays. It was discovered that it has sensitivity.

Specific examples of the compound represented by the general formula [I] include acetylvinylnaphthalene, chloroacetylvinylnaphthalene, bromoacetylvinylnaphthalene, and dichloroacetylvinylnaphthalene.

Trichloroacetylvinylnaphthalene, acetylisopropenylnaphthalene, chloroacetylisopropenylnaphthalene, bromoacetylisopropenylnaphthalene,
Homopolymers such as dichloroacetylisopropenylnaphthalene and trichloroacedelisopropenylnaphthalene, and copolymers containing these as one repeating unit can be mentioned. Copolymer components are not particularly limited, but include, for example, heterocyclic compounds such as vinylpyridine, aromatic vinyl compounds such as styrene and α-methylstyrene vinylnaphthalene, and methacrylic acids such as glycidyl methacrylate and methyl methacrylate. Examples include esters and acrylic esters such as ethyl acrylate.

In these copolymers, the content of the repeating unit compound represented by the general formula [I] 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, after obtaining a polymer containing a repeating unit represented by the general formula (wherein R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), a substituent is added to the aromatic ring by a chemical reaction. By introducing the above, it is possible to produce a polymer containing the repeating unit represented by the general formula [I]. Examples of the polymers obtained by this method include acetyl polyvinylnaphthalene, chloroacetyl polyvinylnaphthalene, bromoacetyl Polyvinylnaphthalene, dichloroacetylpolyvinylnaphthalene, trichloroacetylpolyvinylnaphthalene.

Examples include acetylpolyisopropenylnaphthalene, chloroacetylpolyisopropenylnaphthalene, bromoacetylpolyisopropenylnaphthalene, dichloroacetylpolyisoprobenylnaphthalene, trichloroacetylpolyisopropenylnaphthalene, and the like. The introduction rate of substituents to the naphthalene ring is 5% or more, preferably 1
It is desirable that the content is 0% or more. A polymer containing repeating units represented by the formula [I[] can be produced by any method such as radical polymerization, cationic vehicle method, or anionic polymerization method. Considering that resolution depends on molecular group distribution, it is preferable to obtain a polymer with a narrow molecular weight distribution by an anionic polymerization method.

Although there is no need to particularly limit the molecular group 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 group is 10,000 or more, preferably 20,000 or more. When subjected to X-ray exposure, particularly high sensitivity is required, so the number of molecular groups is desirably 50,000 or more, preferably 100,000 or more.

[Function] In the present invention, the thus obtained polymer is dissolved in a solvent such as toluene, xylene, chlorobenzene, or ethyl cellosolve acetate, and then filtered through a microfilter to obtain a resist solution; Subject to forming process. That is, 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 form a pattern. Here, as an X-ray source, an X-ray source that excites palladium, silicon, rhodium, molybdenum, etc. with an electron beam is in practical use, but the radiation source used in the pattern forming method of the present invention is particularly limited. There's no need.

[Examples] Below, the resist material of the present invention, its manufacturing method, and pattern forming method using the same will be explained in more detail with reference to Examples.

Example 1 Using tetrahydrofuran as a solvent and a hexane solution of butyllithium as a polymerization initiator, 2-vinylnaphthalene was anionically polymerized to obtain a molecule fM of 1.5×10” with a yield of 100%.
A polymer with a narrow molecular weight distribution of 1Olζ. This polymer 20
g was dissolved in 1000 m of carbon disulfide, 3.5 g of aluminum chloride and monochloroacetic acid chloride 6C1 were added,
The reaction was allowed to proceed for 24 hours while stirring at a temperature of 0°C. The reaction mixture was precipitated in methanol containing antioxidant B'HT to recover the reaction product, chloroacetylpoly-2-vinylnaphthalene. The chloroacetylation rate was calculated to be 65% from the elementary amount of the product. Furthermore, from the results of GPC measurement, the value of molecular m dispersity (Mw/Mn) of the product is 1.
2 or less, which was almost the same as the value of poly-2-gonylnaphthalene used as a raw material. The reaction product was dissolved in xylene to give a solution with a concentration of 10%, and the solution was filtered through a microfilter with a pore size of 0.22 μm to prepare a resist solution.

A uniform resist thin film with a thickness of 0.65 μm was formed by spin coating on a silicon wafer at 200° rpm using a spinner. After this was heat-treated at 100° C. for 25 minutes, a pattern was drawn using an electron beam drawing device at an accelerating voltage of 20 KV. After drawing, it was developed by immersing it in a mixed solvent of isoamyl acetate and ethyl cellosolve (volume ratio 3:1) for 1 minute, rinsing with isopropanol, and then drying. From the film thickness measurement of the formed pattern, the sensitivity, that is, the irradiation dose Dg corresponding to the gel point was 4×10 −7 C/ci. Further, as a result of examining the resolution of line/space patterns of different sizes, a resolution of 0.75 μm was obtained.

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

Silicon wafer coating i obtained by the same method as Example 1
The resist was irradiated with electron beam excitation characteristic X-rays (wavelength: 4.6Δ) targeting rhodium, a pattern was formed in the same manner as in Example 1, and the sensitivity was evaluated as L and Y. As a result, Dgi was 25 mj/cm.

Comparative Example 1 Molecule ff111.3x105, chloromethylation rate 45%
Chloromethyl polystyrene (CMS-EX manufactured by Toyo Soda)
(S)) was applied to a thickness of 0.65 μm on a silicon wafer, heat-treated at 120° C. for 225 minutes, and then subjected to electron beam drawing and X-ray 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 irradiation with electron beams or X-rays, the film was developed by immersion in a mixed solvent of isoamyl acetate and ethyl cellosolve (volume ratio 35:65) for 1 minute, rinsed with isopropanol, and then dried. From the results of film thickness measurement, sensitivity D (J' is 1 for electron beams, 9 for OX 10"C/crA and X-rays.
It was 0 mj/crA.

These results demonstrate that the chloroacetylpoly2-vinylnaphthalene obtained in Example 1 of the present invention has high sensitivity compared to CMS.

Example 3 A reaction was carried out under almost the same conditions as in the synthesis method of Example 1, except that monoacetate chloride was triacetate chloride and the reaction temperature was -15°C, and trichloroacetyl poly-2-vinylnaphthalene was synthesized. Obtained. The substitution rate was 17%, and the value of the degree of dispersion MW/Mn was 1.3 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, the following results were obtained: 1)
q' is 50mj10. , I+, and was about 4 times more sensitive than CMS (CMS-DIJ manufactured by Toyo Soda) with similar molecular weight and substitution rate.

Implementation 13'! 14 Polymerization and chloroacetylation reaction were carried out in the same manner as in Example 1 except that the polymerization monomer was isopropenylnaphthalene, to obtain chloroacetylpolyisopropenylnaphthalene with a molecule [2,2X10 2 and a chloroacetylation rate of 50%. Ta.

An 8% xylene solution of the polymer was prepared and exposed to an electron beam.
It was subjected to pattern formation using i-drawing. As a result of pattern drawing in the same manner as in Example 1, Dgi was 3X10'
It had high sensitivity as C/CM, and the resolvable line/space size was 0.75μ, making it possible to form submicron patterns.

Example 5 Etching resistance of the chloroacetylpoly-2-vinylnaphthalene of Example 1 was examined using a parallel plate dry etching apparatus. The etching rate for reactive sputtering using carbon tetrafluoride was measured using a high frequency horn of 350W. The etching rate of silicon oxide is 14
．． 0 O△/min, whereas this resist material has a
The etching rate is less than 1/2 of 50Δ/min,
It is clear that it has extremely high dry etching resistance.

[Effects of the Invention] As explained above, the resist material of the present invention has excellent sensitivity, resolution, and dry etching resistance, and has extremely higher sensitivity to electron beams and X-rays than conventional negative resists. , this method has a great effect on the production of integrated circuits and the like based on lithography techniques that use these radiation sources as radiation sources. 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) General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X_1, X_2, and X_3 represent a hydrogen atom or a halogen atom.) A radiation-sensitive resist material made of a polymer containing a repeating unit represented by: (2) After forming a thin film of radiation-sensitive material on the substrate,
In a pattern forming method that involves irradiation with radiation, development and etching, the radiation-sensitive material has a general formula, ▲mathematical formula, chemical formula, table, etc.▼ (where R is a hydrogen atom or the number of carbon atoms) 1 to 3 alkyl groups, and X_1, X_2 and X_3 represent a hydrogen atom or a halogen atom. . (3) The pattern forming method according to claim 2, wherein the radiation is an electron beam or an X-ray.