JPH05188595A - Formation of chemical intensification type resist pattern - Google Patents

Abstract

PURPOSE:To obtain the method for formation of resist patterns which forms the resist patterns having excellent resolution and pattern shapes without generating whisker-type residues in the patterns by using a negative type chemical intensification resist compsn. CONSTITUTION:An aq. basic soln of 0.1 to 0.25N is used in the developing stage of the method for formation of the chemical intensification type resist patterns successively contg. a stage for applying a resist compsn. contg. a hydrogenated phenolic resin, a melamine resin which is increased in the content of hexamethoxymethyl melamine, an acid generating agent which generates an acid by irradiation with ionization radiations and a solvent as essential components onto a substrate to be treated, an exposing stage, a heating treatment stage and the developing stage.

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 negative chemically amplified resist pattern. More specifically, the present invention is useful in a method for forming a pattern of a semiconductor device, a hydrogenated phenolic resin, a melamine resin having an increased hexamethoxymethylmelamine content, an acid generator and a solvent that generate an acid upon irradiation with ionizing radiation. The present invention relates to a method for forming a chemically amplified resist pattern, which includes the steps of applying a resist composition containing as a main component onto a substrate to be processed, exposing it, heat treating it, and developing it. The pattern forming method according to the present invention can be advantageously used for manufacturing semiconductor devices such as LSI and VLSI, and can provide a highly integrated semiconductor device.

[0002]

2. Description of the Related Art With the high integration of semiconductor integrated circuits, miniaturization of patterns for forming semiconductor integrated circuits is currently required in the industry, and it is strict with respect to a resist material indispensable for forming such patterns. Performance is required. In recent years, a chemically amplified resist has attracted attention as a material developed to meet the requirements for resolution and dry etching resistance. There are several types of chemically amplified resists, and as an example of a negative type, a resist mainly composed of an alkali-soluble base resin, a crosslinking agent, an acid generator and a solvent is known. In this type of resist material, a resist film is usually formed by spin coating, and when this resist film is prebaked and pattern-exposed through a reticle, an acid is generated only in a portion irradiated with ionizing radiation. When charged particles such as an electron beam are used as the ionizing radiation, the resist film is normally scanned without passing through the reticle. By heat treatment after exposure to ionizing radiation, an acid is generated from the acid generator, the acid activates the crosslinking agent, the base resin becomes insoluble, and a negative pattern is formed by development.

In the above-mentioned chemically amplified resist, the acid generated from the acid generator activates many crosslinking agents as a catalyst, so that high sensitivity can be realized and, in comparison with the conventional photoresist, a photosensitizer is used. High resolution can be realized because absorption due to can be reduced. Further, like the conventional resist, since the phenolic resin can be used as the base resin, there are many advantages that the resistance in the subsequent dry etching step is maintained.

However, in this resist pattern forming method, the exposure light source is changed from the conventional g, i-line to K.
When the rF excimer laser is used, there is a problem that the base resin and the cross-linking agent have an influence of absorption and the formed pattern has an inverse tapered shape. Therefore, there is a need for a resist pattern forming method which is excellent in resolution even when a KrF excimer laser is used as an exposure light source and can obtain a good pattern shape. The present inventors have separately prepared a hydrogenated phenol resin, A melamine resin having an increased content of hexamethoxymethylmelamine, a resist composition containing as a main component an acid generator that generates an acid upon irradiation with ionizing radiation, and a solvent, and a pattern forming method using the resist composition. Invented and filed a patent application.

[0005]

However, in the above-mentioned pattern forming method using the chemically amplified resist, a 0.27N alkaline aqueous solution (for example, an alkaline aqueous solution generally used as a developer for a conventional g, i-line resist) (for example, as a developer) is used. Tetramethylammonium hydroxide (T
Using MAH) aqueous solution), although a fine pattern of sub-half micron is resolved, a problem that whiskers-like residue is generated between the patterns has occurred.

Therefore, the present invention provides a method for forming a chemically amplified resist pattern, which can form a resist pattern having excellent resolution without generating whiskers-like residues between the patterns. To aim.

[0007]

According to the present invention, the above-mentioned problems include a hydrogenated phenol resin, a melamine resin having an increased hexamethoxymethylmelamine content, an acid generator which generates an acid upon irradiation with ionizing radiation, and In a pattern forming method, which sequentially includes a step of applying a resist composition containing a solvent as a main component on a substrate to be processed, an exposure step, a heat treatment step, and a developing step, in the developing step.
It can be solved by a resist pattern forming method using a basic aqueous solution of 0.1 to 0.25N.

In the present invention, "ionizing radiation" means visible light, ultraviolet rays, electromagnetic waves such as X-rays, particle beams such as electron beams and ion beams. As described above, the object of the present invention relates to the problem in the exposure of the KrF excimer laser having the wavelength of 248 nm, which has been a conventional problem. It is also effective for pattern formation by exposure to other ionizing radiation. Further, in the present invention, the “acid generator” also includes a compound that promotes the generation of acid by irradiation with ionizing radiation.

The hydrogenated phenolic resin used in the present invention is an alkali-soluble phenolic resin, for example,
Polymers with phenolic hydroxyl groups, such as homopolymers of novolacs, polyvinylphenols (hereinafter referred to as PVP), etc., copolymers of novolacs, polyvinylphenols, etc. with other polymers, are reduced with hydrogen, and some of the benzene rings are cyclohexane rings. Although any structure may be used as long as it has the above structure, hydrogenated polyvinylphenol is particularly preferable because it has an extremely high transmittance at 248 nm. The proportion of hydrogenation may be any as long as the polymer can be dissolved in an alkaline aqueous solution, but the proportion of reduced benzene rings is 30% of the total.
It is preferably not more than weight%. If this reduction rate exceeds 30%, the solubility in an alkaline developing solution such as a 2.38 wt% TMAH aqueous solution which is convenient for semiconductor manufacturing processes will be too low. Further, the hydrogenation ratio is more preferably 5 to 25% by weight. As an example, in the case of hydrogenated polyvinylphenol having a hydrogenation rate of 20% and a weight average molecular weight of 5,400, the transmittance was 72.7% for a film sample having a thickness of 0.7 μm.

In the resist composition used in the present invention, it is preferable to use a melamine resin as a crosslinking agent. Since the melamine resin is industrially supplied and easily available, the use of the melamine resin is industrially very advantageous. However, in such a melamine resin, in addition to the hexamethoxymethylmelamine monomer,
It also contains a large amount of dimers and trimers, and generally the content of hexamethoxymethylmelamine monomer is 80% by weight or less. The melamine resin used in the present invention is obtained by purifying such a melamine resin which is industrially produced and supplied to increase the content of hexamethoxymethylmelamine monomer. Is preferably 85% by weight or more, more preferably 90% by weight or more, still more preferably 95% by weight or more. When the content of the hexamethoxymethylmelamine monomer is less than 80% by weight, the transmittance is lowered and the formed pattern tends to have an inverse taper shape. Also, there is an advantage that the resist sensitivity is improved as the monomer ratio is increased. In addition,
The method for purifying the melamine resin used in the present invention is not particularly limited.

It is incorporated in the resist used in the present invention.
Generated acid generator, that is, acid is generated by irradiation of ionizing radiation
Or a compound that promotes the generation of acid is, for example,
Ph₂I ⁺SbF₆ ^-, Ph₃S⁺SbF₆ ^-Onium salts, such as (Ph
₂I⁺)₂CO₃ ^2-, (Ph₃S⁺)₂CO₃ ^2-Including carbonate ions such as
Salt, Ph₂I⁺HCO₃ ^-, Ph₃S⁺HCO₃ ^-Hydrogencarbonate ion such as
Containing salt, triazine compound having chloromethyl group
Other organic halides, ortho-nitrobenzyl alcohol
Tosylate compounds such as sulfonic acid esters
The organic brominated compounds shown below
Is particularly preferable because it has excellent thermal stability and storage stability.

[0012]

[Chemical 1]

[0013]

[Chemical 2]

[0014]

[Chemical 3]

[0015]

[Chemical 4]

[0016]

[Chemical 5]

[0017]

[Chemical 6]

[0018]

[Chemical 7]

As a solvent to be added to the resist composition used in the present invention, a necessary amount of other components is dissolved,
Any compound may be used as long as it has excellent coating properties on the substrate, and examples thereof include alcohols, ketones, ethers, alcohol ethers, esters, cellosolve esters, propylene glycols, diethylene glycols and halogenated compounds. Hydrocarbons, aromatic hydrocarbons, and the like are used, but it is particularly preferable to use ethyl lactate or propylene glycol monomethyl ether acetate (PGMEA), which is a solvent having excellent safety and a high boiling point.

In the resist composition used in the present invention, the blending ratio of the melamine resin having an increased hexamethoxymethylmelamine content is not particularly limited, but preferably 2 to 30 parts by weight per 100 parts by weight of the hydrogenated phenol resin. And more preferably 5 to 20 parts by weight. If the blending amount of the melamine resin is too small, the degree of crosslinking will be insufficient, and if it is too large, the absorption by melamine will be large, and the transmittance will be lowered as a whole, making it difficult to obtain the desired improvement effect.

The amount of the acid generator compounded in the resist composition used in the present invention is not particularly limited, but is preferably 0.2 to 10 parts by weight, more preferably 0.5 to 5 parts by weight per 100 parts by weight of the hydrogenated phenol resin. It is a department. If the amount of the acid generator compounded is too small, the sensitivity is lowered. On the contrary, if it is too large, the transmittance is lowered or the coating characteristics are deteriorated.

The amount of the solvent blended in the resist composition used in the present invention is not particularly limited, but it is generally used in such an amount that the solid concentration of the resist composition is about 4 to 30% by weight.

The pattern formation method of the chemically amplified resist according to the present invention can be performed by the same processing steps as the forming method when the generally known chemically amplified resist is used. That is, for example, a desired pattern is formed through a step of sequentially applying the resist composition on a substrate, a first heat treatment step, an ionizing radiation irradiation step, a second heat treatment step, and a development step. can do.

The method of forming a resist pattern according to the present invention is particularly characterized by the developing step in the pattern forming method using the above resist composition. That is, in the pattern forming method of the present invention, the concentration (normality) of the developer is
A basic aqueous solution of 0.1 to 0.25N is used. If the concentration of the basic aqueous solution is less than 0.1 N, the resolution tends to be low and the time required for development tends to be long, and conversely, if the concentration is more than 0.25 N, as described above, there is a gap between fine patterns. A whiskers-like residue tends to occur on the surface, leaving a problem for practical use. The range of this concentration is 0.15 to 0.20 to further enhance the effect.
More preferably N. Since the optimum developing time varies depending on the concentration of the developing solution, it is better to optimize it depending on the pattern shape formed, but it is generally 30 to 180 seconds.

Specific examples of the basic aqueous solution used in the present invention include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium silicate, and ammonia, and primary amines such as ethylamine and propylamine. Secondary amines such as diethylamine and dipropylamine, tertiary amines such as trimethylamine and triethylamine, alcohol amines such as diethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethylhydroxymethyl Aqueous solution of quaternary ammonium salt such as ammonium hydroxide, triethylhydroxymethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide Although etc., tetramethylammonium hydroxide, tetraethylammonium hydroxide, the use of trimethyl hydroxymethyl ammonium hydroxide is particularly preferred.

[0026]

According to the present invention, as described above, and as will be described in more detail in the following examples, when a pattern is formed using a chemically amplified resist, 0.1 to 0.25 is used as a developing solution in a developing process. By using the basic aqueous solution of N, it is possible to prevent the generation of residues and the deterioration of resolution.
A highly integrated semiconductor device can be manufactured. Therefore, the method for forming a resist pattern according to the present invention is
It is particularly effective for manufacturing semiconductor devices such as SI and VLSI.

[0027]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but it goes without saying that the scope of the present invention is not limited to the following Examples.

Reference Example 1 (Preparation Example) 100 parts by weight of hydrogenated polyvinylphenol resin (molecular weight: 5200) having a hydrogenation rate of 10% by weight, 15 parts by weight of a melamine resin having a content of 95% by weight of hexamethoxymethylmelamine, and an acid generator. 2 parts by weight of tris (2,3-dibromopropyl) isocyanurate was added to 490 parts by weight of ethyl lactate and mixed and dissolved at room temperature to prepare a resist solution.

Reference Example 2 (Preparation Example) 100 parts by weight of hydrogenated polyvinylphenol resin (molecular weight: 5400) having a hydrogenation rate of 20% by weight, 15 parts by weight of a melamine resin having a content of hexamethoxymethylmelamine of 95% by weight, and an acid generator. 2 parts by weight of CH ₃ -C ₆ H ₄ -SO ₂ CBr ₃ was added to 490 parts by weight of propylene glycol monomethyl ether acetate and mixed and dissolved at room temperature to prepare a resist solution.

Example 1 The resist solution prepared in Reference Example 1 was applied on a silicon substrate by a spin coating method to a thickness of about 1.0 μm, prebaked on a hot plate at 105 ° C. for 90 seconds, and then at a wavelength of 248 nm.
Was exposed to the laser light. Immediately after the exposure, heat treatment was carried out on a hot plate at 120 ° C. for 60 seconds, and puddle development was carried out for 120 seconds with a 0.17N TMAH aqueous solution. The obtained pattern resolved a line and space pattern of 0.30 μm at an exposure dose of 45 mJ / cm ² in a ratio of 1: 1. The pattern shape was almost vertical, and no generation of residue was observed.

Example 2 The resist solution prepared in Reference Example 2 was applied on a silicon substrate by a spin coating method to a thickness of about 0.7 μm, prebaked on a hot plate at 90 ° C. for 90 seconds, and then laser light having a wavelength of 248 nm was used. Exposed. Immediately after the exposure, heat treatment was performed on a hot plate at 105 ° C. for 60 seconds, and dip development was performed for 90 seconds with a 0.17N TMAH aqueous solution. The obtained pattern resolved a line and space pattern of 0.30 μm at an exposure dose of 50 mJ / cm ² in a ratio of 1: 1. The pattern shape is almost vertical,
No generation of residue was observed.

Example 3 The resist solution prepared in Reference Example 2 was applied on a silicon substrate by a spin coating method to a thickness of about 0.7 μm, prebaked on a hot plate at 105 ° C. for 90 seconds, and then X-ray (SO
R). Immediately after exposure on hot plate 1
Heat treatment at 20 ℃ for 60 seconds, then use 0.17N TMAH aqueous solution 1
Dip development was performed for 00 seconds. The obtained pattern resolved the line and space pattern of 0.30 μm, which is the minimum dimension of the mask, in a ratio of 1: 1. The pattern shape was almost vertical, and no generation of residue was observed.

Comparative Example 1 The resist solution prepared in Reference Example 1 was applied on a silicon substrate by a spin coating method to a thickness of about 1.0 μm, prebaked on a hot plate at 105 ° C. for 90 seconds, and then at a wavelength of 248 nm.
Was exposed to the laser light. Immediately after exposure, heat treatment was carried out on a hot plate at 120 ° C. for 60 seconds, and paddle development was performed for 25 seconds with a 0.27N TMAH aqueous solution. The obtained pattern resolved a line and space pattern of 0.30 μm at an exposure dose of 48 mJ / cm ² , but the pattern shape was slightly reverse tapered,
A whisker-like residue was observed in the pattern below 0.35μm line & space.

Comparative Example 2 The resist solution prepared in Reference Example 2 was applied on a silicon substrate to a thickness of about 0.7 μm by a spin coating method, prebaked on a hot plate at 90 ° C. for 90 seconds, and then laser light having a wavelength of 248 nm was used. Exposed. Immediately after the exposure, heat treatment was performed on a hot plate at 105 ° C. for 60 seconds, and paddle development was performed for 25 seconds with a 0.27N TMAH aqueous solution. The obtained pattern resolved a line and space pattern of 0.30 μm at an exposure dose of 52 mJ / cm ² , but the pattern shape was slightly reverse tapered,
A whisker-like residue was observed in the pattern below 0.35μm line & space.

[0035]

As described above, according to the present invention,
Resist pattern using a chemically amplified resist composition containing a hydrogenated phenol resin, a melamine resin having an increased hexamethoxymethylmelamine content, an acid generator that generates an acid upon irradiation with ionizing radiation, and a solvent as main components As the development rate of the development process
By using the basic aqueous solution of 0.1 to 0.25 N, a pattern excellent in resolution and pattern shape can be obtained without generating whiskers-like residues in the pattern.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03F 7/32 7124-2H H01L 21/027

Claims (5)

[Claims] 1. A resist composition comprising a hydrogenated phenol resin, a melamine resin having an increased hexamethoxymethylmelamine content, an acid generator that generates an acid upon irradiation with ionizing radiation, and a solvent as main components. A basic aqueous solution of 0.1 to 0.25N is used in the developing step of the method for forming a chemically amplified resist pattern, which sequentially includes a step of applying on a substrate, an exposure step, a heat treatment step and a developing step. Pattern formation method. 2. The pattern forming method according to claim 1, wherein the basic aqueous solution is 0.15 to 0.20 N. 3. The pattern forming method according to claim 1, wherein the basic aqueous solution is an aqueous solution of tetramethylammonium hydroxide or tetraethylammonium hydroxide. 4. The pattern forming method according to claim 1, wherein the hydrogenated phenol resin is hydrogenated polyvinylphenol. 5. The pattern forming method according to claim 1, wherein the melamine resin having an increased hexamethoxymethylmelamine content has a hexamethoxymethylmelamine content of 85% by weight or more.