JPS6238456A - Formation of pattern by dry development - Google Patents

Abstract

PURPOSE:To form a prescribed pattern with designed dimensional accuracy by forming a film of a specified resist material contg. silicon on a substrate to be processed, irradiating high energy beams on the resist film and decomposing and evaporating the irradiated part of the resist material. CONSTITUTION:A film of a resist material contg. silicon obtd. by (co) polymerizing at least one kind of substituted acetylene compound represented by the formula is formed on a substrate to be process, high energy beams are irradiated on the resist film, and the irradiated part of the resist material is decomposed and evaporated. The preferred silicon content in the resist material is >=10wt%. In the formula, R1 is (un)substituted silyl and R2 is H, an (un)satd. aliphatic group, an (un)substituted aromatic group or (un)substituted silyl, and these are same or different each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for forming a resist pattern used in a process for manufacturing semiconductor devices such as LSI, and particularly to a method for forming a resist pattern that does not require wet development.

Conventional Technology Conventionally, in the production of ICs and LSIs, a substrate to be processed is coated with an organic composition such as a polymer compound called a resist, and a latent image is formed on the resist by irradiating it with high-energy radiation in a pattern. A wet development method has been used in which a patterned resist film is formed by immersing the resist in a suitable solvent or spraying the resist with a solvent, thereby dissolving or leaving the high-energy ray irradiated portion. However, in recent years, with the miniaturization of LSI elements, it has become difficult to achieve sufficient processing precision in the wet development due to swelling of the resist and the like. Furthermore, since organic solvents are used, there are problems in waste liquid treatment and difficulty in automation. Therefore, a dry development method has been proposed in which the resist is developed without using a solvent.

G. N. Taylor et al.
Polydichloropropyl acrylate, which is an organic polymer compound, is mixed with a monomer that reacts with the polymer by irradiating it with high-energy rays and is incorporated into the polymer to form a resist layer, and after irradiating the high-energy rays, proposed a method in which monomers are removed from the resist layer in unirradiated areas by heating the sample under vacuum, and then the resist in the unirradiated areas is etched away by plasma etching to form a resist pattern. Journal of the Electrochemical Society (Jour
nalof the old electrochemical 5
ociety), 127.2665 (1980)
, and Journal of Vacuum Science and Technology.
m 5science and Technology)
, 19.872 (1981)].

Furthermore, many dry development methods have been developed based on ideas similar to this method. For example, for sludge, we proposed using polyisopropenyl ketone as a polymer material and adding bisazides to it [Journal of Vacuum Science and Technology (Journal of Vacuum Science and Technology)].
Vacuum 5science and Techno
19.1351 (1981)]
, Yoneda et al. proposed a methacrylic acid polymer with silanes added [Proceedings of the 42nd Annual Conference of the Japan Society of Applied Physics, 9a-G-4, p. 354 (1981)
[Reference] However, although these methods perform development using a dry process, a wet method must be used to apply the resist material to the substrate. Furthermore, since the base polymer is the same for both the image area and the irradiated pattern area, the etching selection ratio during dry development between the unirradiated area and the irradiated pattern area cannot be sufficiently large, and therefore the film loss in the unirradiated area is large.
There is a drawback that a pattern with a good shape ratio cannot be formed.

Furthermore, Tamano et al. have proposed a method in which a methacrylic polymer is formed into a resist film by a dry method using plasma polymerization, and then dry development is performed after pattern irradiation [Kobunshi Ronshu, 38. 657 (1981)]. With this method, it is possible to completely dry the resist process, but since the base polymer is the same, the etching selectivity between the irradiated and non-irradiated areas is still insufficient, and if dry development is performed, the pattern area A significant film reduction occurs, so
It is not practical enough to be introduced into the process.

Based on a completely different idea from these methods, H.

Ito et al. (H, Ito) have proposed a dry development resist. They added an onium salt that produces a Lewis acid or Brønsted acid when irradiated with high-energy rays to end-treated polyphthalaldehyde, thereby selectively decomposing and evaporating the polyphthalaldehyde in the portions irradiated with high-energy rays. Therefore, we discovered that self-development is possible.

Although this method requires the use of a wet method in terms of applying the resist material to the substrate, it is an excellent method in that it does not require any development process [Polymer Engineering and Science (Polymer Bng.
inering and 5science)
, 23. 1012 (1983)].

On the other hand, when processing a substrate after forming a resist pattern, the parts of the substrate not covered by the resist are chemically etched by immersing the substrate in a corrosive solution.
A wet method has been used in which a desired pattern is formed on a substrate to be processed by peeling off the resist. However, in recent years, with the miniaturization of LSI elements, the wet method described above cannot achieve sufficient processing accuracy due to side etch lag, and dry etching methods such as etching using high-frequency plasma of gases such as carbon tetrafluoride and carbon tetrachloride are being used. has come to be used. For this reason, resist materials used for pattern formation are required to have high sensitivity and resolution to energy rays as well as high resistance to dry etching. However, in the case of the above-mentioned self-developing type resist, there is a drawback that as the sensitivity is improved, the resistance to dry etching is lowered because it becomes easier to decompose.

Another important problem associated with the miniaturization of LSI devices is that as the dimensions of the device wiring become smaller, the wiring resistance increases, making it impossible to increase the speed of the device, so it is necessary to increase the thickness of the wiring. This creates a considerable level difference on the surface of the processed substrate. In order to process a substrate surface having such a step difference, it is necessary to use a fairly thick resist layer. However, when a thick resist layer is used, problems arise such as dry development takes time, and the difference in thickness causes the resist to be out of focus, resulting in a decrease in resolution.

In order to solve this problem, a method has been proposed in which a resist is formed in multiple layers instead of in one layer to form a thick, fine pattern with a high shape ratio. That is, after forming a thick organic polymer film as the first layer and forming a thin resist layer as the second layer on top of it, the second resist film is irradiated with high energy rays, and after pattern formation. Using the obtained pattern as a mask, the organic polymer of the first layer is anisotropically etched to obtain a pattern with a high shape ratio. However, the dry development resist described above had low resistance to oxygen plasma used in anisotropic etching, and could not be used as a mask when etching the organic polymer of the second layer.

Problems to be Solved by the Invention As mentioned above, with the miniaturization of LSI elements, etc., there is a need for IJ Sogelafy technology that enables fine precision processing. That is, in order to realize miniaturization of LSI elements and the like, it is necessary to form a predetermined pattern on a substrate to be processed with dimensional accuracy as designed.

However, conventional wet development methods have problems such as swelling of the resist, making it impossible to achieve sufficient processing accuracy. Therefore, the dry etching method has attracted attention, and various dry development resists as described above have been proposed.

However, the above-mentioned resist has low resistance to the oxygen plasma used in the anisotropic etching that will be performed later.
This was insufficient for practical use as a mask for dry etching of substrates to be processed.

Furthermore, in connection with miniaturization, it is necessary to increase the thickness of the wiring and reduce the wiring resistance, but this creates a large step on the surface of the processed substrate, which causes the problem of reduced accuracy. be. It is thought that this problem can be solved by multi-layering the resist, first patterning the upper layer resist, and using this as a mask to pattern the lower layer resist, but this also has the problem of oxygen plasma resistance of the upper layer resist, and so far It's not a sufficient solution.

Therefore, it is extremely important to solve the problems of the above conventional methods and to develop a method that enables micro-precision processing of substrates to be processed, in order to miniaturize LSI elements, etc., and the emergence of such technology is essential. There is a demand for

Therefore, an object of the present invention is to provide a method for forming fine patterns using a resist material that can be self-developed by high-energy ray irradiation and has sufficient oxygen plasma resistance to be used as the second layer of a two-layer resist. It's about doing.

Means for Solving the Problems In view of the current state of resist materials and pattern forming methods as described above, the inventors have conducted various studies to develop a new resist pattern forming method, and have developed a material for resist pattern forming. The present invention has been completed based on the discovery that it is extremely effective to add a sensitizer to an organic polymer obtained by polymerizing or copolymerizing a specific substituted acetylene.

That is, the resist pattern forming method of the present invention uses the following general formula (I): R, -C≡C-R2 (1) (wherein R1 is a silyl group or a substituted silyl group, and R2
represents one type selected from the group consisting of a hydrogen atom, a saturated or unsaturated aliphatic group, an aromatic group, a substituted aromatic group, a silyl group, or a substituted silyl group, which may be the same or different from each other) forming a film of a silicon-containing resist material obtained by polymerizing or copolymerizing at least one selected from substituted acetylene compounds on a substrate to be processed; irradiating the resist film with high-energy rays;
It is characterized by forming a resist pattern on the substrate to be processed by decomposing and evaporating the resist material in the irradiated area.

Further, a two-layer resist film is formed on the substrate to be processed,
Next, when forming a resist pattern on the substrate to be processed by dry etching the lower resist film using the upper resist pattern obtained by exposing, drawing, and developing the upper resist as a protective film, the above-mentioned silicon-containing resist is used as the upper resist. Similarly, a pattern can be formed by dry development by using a material.

The silicon content of the silicon-containing resist material is preferably 10% by weight or more. Therefore, it is necessary to select monomers so that at least one substituted acetylene compound used in polymerization or copolymerization contains a silyl group, and the silicon content in the resulting polymer is at least 10% by weight. By configuring the pattern forming material in this way, a resist having sufficient plasma resistance can be obtained.

Examples of the silyl group or substituted silyl group in the substituted acetylene compound of general formula (I) include trimethylsilyl group, dimethylethylsilyl group, diethylmethylsilyl group,
Examples include triethylsilyl group, dimethylphenylsilyl group, dimethyl-n-hexylsilyl group, 1-()limethylsilyl)-methyldimethylsilyl group, and 1-()limethylsilyl)-ethyldimethylsilyl group. Examples of the alkyl group include linear alkyl groups such as methyl, ethyl, butyl, hexyl, octyl, decyl, dodecyl, and hexadecyl, and branched alkyl groups such as t-butyl, 1-methylpropyl, and 2-methyl. Examples include propyl, 2-methylbutynobeneopentyl, 1-methylpentyl, 2-methylpentyl, 4-methylpentyl, and 2-ethylhexyl groups. Further, examples of the unsaturated aliphatic group include a vinyl group and an allyl group.

Further, examples of substituted and unsubstituted aromatic groups include phenyl group, methylphenyl group, chloromethylphenyl group, and the like.

Specific examples of these silicon-containing acetylenes include 1-)
Examples include dimethylsilyl-1-propyne and 1-(trimethylsilyl)-ethyldimethyl-1-propyne.

In addition, examples of acetylene monomers that can be copolymerized with these silicon-containing substituted acetylenes include t-butylacetylene,
Alkylacetylenes such as 2-octyne, 1-methyl-
Examples include arylacetylenes such as 2-phenylacetylene and 1-chloro-2-phenylacetylene.

The substituted acetylene polymer is a white to pale yellow fibrous or powdery solid. Its molecular weight is usually 1000 or more as measured by weight average molecular weight (light scattering method).

The silicon-containing cyst material useful in the method of the present invention is effective for dry development with high energy radiation, such as deep ultraviolet, X-
Examples include lines.

The silicon-containing resist material used in the present invention can also contain a sensitizer, which can increase the sensitivity of the resist material to high-energy radiation.

Such sensitizers include (i) benzophenone (
ii) Benzoin type (iii) Acetophenone type (
iv) Triplet sensitizers such as thioxanthone type (V) anthraquinone type can be used.

Specifically, the details are as follows.

(1) Benzophenone type (4,4' dichlorobenzophenone) Kayacure M B P (2)
Benzoin type (3) Acetophenone type [Mitsubishi Yuka Sandray (SANDR 8Y)] 4) Thioxanthone type 1r1 Kayacure PTX, Kayacure DITX (5) Anthraquinone type ○ CH (Mitsubishi Yuka PDO) CH, / \CH3 The above invention In the resist, the silicon content is mainly important, and the types of alkyl groups in the substituents R3 and R2, chain length, etc. are not so important. However, for example, as the number of carbon atoms in the alkyl group increases, the silicon content decreases, so care must be taken in selecting monomers during polymerization or copolymerization. Furthermore, if the amount of the sensitizer added is too small, the sensitivity to high energy rays will decrease, and if it is too large, the plasma resistance will be reduced, so it is preferably 5-40% by weight.
It is desirable that it be within the range of . However, in any case, it is essential that the silicon content in the resulting resist be 10% or more in order to impart sufficient plasma resistance to the pattern forming material.

Function: The resist according to the present invention functions as a positive type against ultraviolet rays, deep ultraviolet rays, X-rays, and the like.

In addition, in microfabrication of a substrate to be processed using a multilayer resist, the upper layer resist pattern is used as a protective mask to etch the lower organic polymer film with oxygen plasma, so the upper layer resist has sufficient resistance to oxygen plasma. It is necessary to have

The oxygen plasma resistance of the resist material of the present invention is determined by the silicon content. It is known that if the content is at least 10%, it becomes almost zero. Therefore, the monomers are selected so that the silicon content is 10% by weight or more.

Further, in the pattern forming method using a resist material of the present invention, an organic polymer film is first formed on a substrate to be processed, if necessary. This organic polymer film may be an aromatic-containing polymer or various known photoresists, such as AZ series from Shipley, 0FPRSTPR from Tokyo Ohkabu.

Examples include each series such as 03RS OMR. The organic polymer film is formed by dissolving these in a suitable solvent and applying the resulting solution by a spin code method, a spray method, or the like. Furthermore, an organic polymer film may be formed in a dry process using a plasma polymerization method or the like.

Next, the silicon-containing resist film (which may contain a sensitizer) of the present invention is formed directly on the first layer of the organic polymer film or on the substrate to be processed. Similar to the first layer, this is done by dissolving the resist material in a suitable solvent and applying the resulting solution by a spin code method, a spray method, or the like.

Alternatively, the resist may be formed by a dry process using a vapor deposition method.

The resulting single layer or multilayer resist is then subjected to a patterning step. First, in the case of a single-layer silicon-containing resist film, the mask is aligned as necessary, and high-energy rays are irradiated through this mask to decompose and evaporate the silicon-containing resist material in the irradiated area, forming a mask pattern. By baking, a mask pattern for processing the substrate to be processed can be obtained.

Further, in the case of a multilayer resist, as a first step, a mask pattern is first baked onto a silicon-containing resist film as an upper layer resist as described above to form a mask for forming a lower resist pattern. Next, as a second step, the organic polymer film is etched, and this operation is carried out by oxygen plasma etching using the pattern of the silicon-containing resist film as a mask. This etching of an organic polymer film by oxygen plasma etching is exactly the same technology as plasma ashing, which is used to peel off a resist film after the completion of etching processing of a substrate by conventional photoetching operations, and is phenomenologically This method uses the chemical reaction between the atomic oxygen generated in oxygen plasma and the polymer to reduce the polymer to a lower molecular weight, and the oxidation of the low-molecular resin by the carbon dioxide force and its decomposition and vaporization into water.

This operation can be carried out, for example, in a cylindrical plasma etching apparatus, a parallel plate plasma etching apparatus, using oxygen as the reactive gas, ie the etching gas.

As described above, according to the method of the present invention, a highly accurate pattern can be formed because wet development, which causes a decrease in resolution, is not performed in forming a fine resist pattern. Further, the substrate is processed using this resist pattern as a mask, and dry etching methods such as sputter etching, gas plasma etching, and ion beam etching can be used as the processing method.

Etching processing using a single-layer or multi-layer resist method containing the resist film of the present invention is completed by stripping the resist film. The resist film can be peeled off simply by dissolving the organic polymer material of the first layer.

This organic polymer material is any photoresist, and is not subject to any alteration (hardening, etc.) during the above photoetching operation.
Since this is not the case, the organic solvent of each known photoresist itself can be used. Alternatively, it is also possible to peel off without using a solvent by treatment such as plasma ashing.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Production Examples, but the scope of the present invention is not limited by these Examples.

Production Example 1 - 112 g of trimethylsilyl-1-propyne was dissolved in 1 p of toluene, and 8 g of tantalum pentachloride was added as a catalyst.
g was added thereto and reacted at 80°C for 24 hours. The reaction solution was poured into methanol to obtain a white polymer.

Production Examples 2 to 6 In Production Example 1, 1-dimethylethylsilyl-1-propyne (
Production Example 2), 1-dimethylphenylsilyl-1-propyne (Production Example 3), 1-dimethylchloromethylsilyl-1
-Propyne (Production Example 4), 1-()limethylsilyl)-
Methyldimethylsilyl-1-propyne (Production Example 5), l
A white polymer was similarly obtained using -(trimethylsilyl)ethyldimethylsilyl-1-propy/(Production Example 6).

Example 1 1 g of the polymer obtained in Production Example 1 and 0.1 g of 2-ethylanthraquinone were dissolved in 100 ml of xylene, coated on a silicon wafer to a thickness of about 0.2 μm, and heated at 100° C. for 30 minutes in a nitrogen stream. I pre-baked it.

Next, a mask was placed on this wafer, and a deep ultraviolet mask aligner (
When a pattern of deep ultraviolet rays was irradiated for 30 minutes using Canon's PLA 521), the polymer in the far ultraviolet irradiated area was decomposed and a positive 0.5 μm line/space pattern was formed.

Further, etching was performed using a parallel plate reactive ion etching apparatus using oxygen gas as an etchant gas (applied power 10 W, etching chamber pressure 10 m
Torr). Under these conditions, the etching rate of the polymer was 5 nm/min or less, and the etching rate of ΔZ resist (Sibley) was 1100 n/min.

Example 2 The exposure time required for pattern formation with deep ultraviolet rays and the etching rate with oxygen gas were measured for the polymers obtained in Production Examples 2 to 6 according to the method of Example 1, and the results were as follows: Now shown in the table.

Example 3 In place of 2-ditylanthraquinone in Example 1,
7 tons of thioxa, dibenzofuran, 4゜4゛dichlorobenzophenone, PDO (Mitsubishi Yuka) Sandray (SAN)
When the exposure time required for pattern formation was measured using deep ultraviolet rays using DRAY (Mitsubishi Yuka), the results were shown in Table 2 below.

Example 4 In Example 1, when the amount of 2-ethylanthraquinone added was 0.05 g, 0.2 g, and 0.4 g, the exposure time necessary for pattern formation with deep ultraviolet rays and the etching rate with oxygen gas were measured. The results are shown in Table 3 below.

Table 3 Example 5 Silicon wafer AZ1350 resist (Sibley) was applied to a thickness of 2 μm and prebaked at 100° C. for 30 minutes. A resist consisting of the polymer obtained in Production Example 1 and 2-ethylanthraquinone was applied onto this ΔZ resist to a thickness of about 0.2 μm in the same manner as in Example 1.
Prebaked at 0°C for 30 minutes.

After blivating, the mask was placed over the mask and exposed to deep ultraviolet mask aligner for 30 minutes. As a result, 0 on the ΔZ resist
．． A 5 μm line and space pattern was formed. Thereafter, parallel plate reactive ion etching was performed using oxygen gas as an etchant. After 25 minutes of etching, the AZ resist in the areas not covered by the pattern completely disappeared, leaving 0.5 μm lines and spaces with a thickness of 2.5 μm.
A pattern of 1 μm could be formed. Furthermore, this pattern could be easily peeled off with acetone.

As described in detail, the pattern forming method using a silicon-containing resist material according to the present invention or a resist composed of the same and a sensitizer exhibits positive characteristics with respect to deep ultraviolet rays, X-rays, and the like. Moreover, the irradiated area evaporates during exposure, allowing for so-called self-development, in which a pattern can be formed without wet development. Therefore, there are no problems with wet development such as swelling during development.

Furthermore, since it contains silicon, it has high resistance to oxygen etching, and therefore can be used as an upper layer resist of a two-layer resist having a thick organic polymer in the lower layer. When used as a two-layer resist, the film thickness may be thin, so resolution is improved. Further, it is also possible to form a submicron pattern with a significantly high shape ratio on a substrate having steps.

The above can be expected to bring about significant effects in the manufacture of semiconductor devices and the like.

Claims (5)

[Claims] (1) The following general formula (I): R_1-C≡C-R_2(I) (In the formula, R_1 is a silyl group or a substituted silyl group, and R
_2 represents one type selected from the group consisting of a hydrogen atom, a saturated or unsaturated aliphatic group, an aromatic group, a substituted aromatic group, a silyl group, or a substituted silyl group, and may be the same or different from each other) A film of a silicon-containing resist material obtained by polymerizing or copolymerizing at least one substituted acetylene compound selected from substituted acetylene compounds is formed on a substrate to be processed, and the resist film is irradiated with high-energy rays, and the irradiated portions are A method for forming a pattern by dry development, characterized in that a resist pattern is formed on a substrate to be processed by decomposing and evaporating a resist material. (2) A two-layer resist film is formed on the substrate to be processed, and the silicon-containing resist material is used as the upper resist film, and the upper resist pattern obtained by dry developing it is used as a protective mask. 2. The method of forming a pattern by dry development according to claim 1, wherein the lower resist film is dry-etched. (3) The method for forming a pattern by dry development according to claim 1 or 2, wherein the silicon content of the silicon-containing resist material is 10% by weight or more. (4) The silicon-containing resist material has the general formula (
4. The method for forming a pattern by dry development according to claim 3, which is a copolymer of the silicon-containing acetylene monomer (I) and the silicon-free acetylene monomer. (5) The method for forming a pattern by dry development according to claim 3 or 4, wherein the silicon-containing resist material contains 5 to 40% by weight of a sensitizer.