JPH0346814B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a positive photoresist composition sensitive to radiation. [Prior art and its problems] Formation of fine patterns can be performed, for example, by spin coating a positive photoresist composition on a wafer;
It is applied using a coating method such as dip coating or spray coating, and the solvent is evaporated to form a photosensitive layer on the wafer. Radiation is irradiated through a mask pattern, and the irradiated areas are selectively exposed using a developer. This is done by removing. The conventionally used positive photoresist composition is 3, which is synthesized from trihydroxypenzophenone and naphthoquinonediazide sulfonyl chloride.
Functional quinonediazide-based photosensitive compounds, alkali-soluble coating film-forming materials that are novolak resins obtained by condensing phenol derivatives and aldehyde derivatives, or polyvinyl alcohol, copolymers of styrene and acrylic acid, methacrylic acid and methacrylic acid. These conventional positive photoresist compositions are composed of an alkali-soluble film-forming material such as a copolymer with an alkyl ester and a solvent such as ethyl cellosolve acetate, but these conventional positive photoresist compositions have insufficient solubility of the photosensitive compound in the solvent. However, even if dissolved, the photosensitive compound precipitated when stored for a long period of time, impeding the formation of fine patterns. In recent years, positive photoresist compositions containing a tetrafunctional quinonediazide-based photosensitive compound synthesized from tetrahydroxybenzophenone and naphthoquinonediazide sulfonyl chloride have been developed as positive photoresist compositions with higher performance than conventional ones, such as high resolution. (Japanese Unexamined Patent Publications No. 118744/1982, No. 185741/1983), but this positive photoresist composition also has the above-mentioned conventionally known trifunctional quinonediazide photosensitive composition. It has been found that there is a storage safety problem equal to or greater than that of positive photoresist compositions containing the compound, and a solution to this problem has been strongly desired. [Means for Solving the Problems] As a result of extensive research in order to obtain a positive photoresist composition with high performance and good applicability, the present inventors discovered that a tetrafunctional quinonediazide photosensitive compound The present invention was completed based on the knowledge that storage stability can be significantly improved by controlling specific impurities contained in a positive photoresist composition to a specific amount or less. That is, the present invention aims to provide a method for producing a positive photoresist composition of high industrial value, and the gist thereof is to provide a quinonediazide-based photoresist composition synthesized from tetrahydroxybenzophenone and naphthoquinonediazide sulfonyl chloride. In producing a positive photoresist using a photosensitive compound, (a) the photosensitive compound or a composition containing the photosensitive compound, a novolac resin, and a solvent are analyzed under the following conditions; Column: octadecylsilane is chemically bonded; Totally porous silica gel eluent: acetonitrile/water/acetic acid (volume ratio 55/
43/2) Detection: Analyzed by ultraviolet absorbance analysis (wavelength 254 nm) liquid chromatography, (b) In the chromatogram, all four hydroxyl groups of tetrahydroxybenzophenone reacted with naphthoquinonediazide sulfonyl chloride. The retention time of the sulfonic acid ester peak obtained by
The area of the peak with a retention time of 0.75−0.9 times is
The present invention provides a method for producing a positive photoresist, characterized in that a photosensitive compound or a composition containing the photosensitive compound is selected whose total area of all peaks due to the photosensitive compound is 3% or less of the total area. The tetrafunctional quinonediazide photosensitive compound (hereinafter abbreviated as PAC-4) synthesized from tetrahydroxybenzophenone and naphthoquinonediazide sulfonyl chloride used in the present invention includes 2,
3,4,4'-tetrahydroxybenzophenone and 1,2-naphthoquinone-2-diazide-5-
A typical example is a quinonediazide compound synthesized from sulfonyl chloride or 1,2-naphthoquinone-2-diazide-4-sulfonyl chloride. These PAC-4 can be produced by a method such as dissolving the above-mentioned raw materials in a solvent such as dioxane and reacting them using an alkali carbonate such as sodium carbonate, an amine such as triethylamine, etc. as a deoxidizing agent. The obtained PAC-4 is a quinonediazide compound in which all four hydroxyl groups of tetrahydroxybenzophenone are substituted to form a sulfonic acid ester (hereinafter abbreviated as 4-substituted product), and a quinonediazide compound in which all four hydroxyl groups of tetrahydroxybenzophenone are substituted to form a sulfonic acid ester (hereinafter abbreviated as 4-substituted product), and less than 4 substituted hydroxyl groups. PAC-4 used in the present invention preferably contains at least 10% by weight of a 4-substituted compound. When this PAC-4 is analyzed by liquid chromatography, many peaks are observed in addition to the peak of the 4-substituted product. FIG. 1 is a diagram showing an example of a liquid chromatograph of PAC-4 of the present invention. The conditions for liquid chromatography analysis are as follows. Column: Fully porous silica gel chemically bonded with octadecylsilane (manufactured by M Magel, West Germany,
NUCLEOSIL・ODS) 7 μm, 300 mmL Eluent: Acetonitrile/Water/Acetic acid = 55/43/2
(Volume ratio) Eluent flow rate: 1 ml/min Detection: Detected by ultraviolet absorbance analysis (wavelength 254 nm). In FIG. 1, 1 is a peak indicating a 4-substituted product;
2 is a peak indicating a quinonediazide compound in which two hydroxyl groups have been substituted to form a sulfonic acid ester, and 3 is a peak group indicating harmful byproducts, which is 0.75 to 0.9 times the retention time of the tetrasubstituted product peak. This is a group of peaks corresponding to the retention time of . In the present invention, it is important to select a photosensitive compound with a small amount of the above-mentioned harmful by-products, and its peak area is 3 of the total area of all peaks up to the point where the peak indicating the 4-substituted product stops appearing. % or less, preferably 2% or less, more preferably 1.5% or less. If more than 3%, for example 5%, is present, the photosensitive compound will be completely dissolved in the solvent and/or the mixture of the solvent and the alkali-soluble coating film-forming material coexisting as a resist composition, but after 1 to 3 months, the photosensitive compound will dissolve. begins to precipitate. If it is present in an amount exceeding 5%, it will not completely dissolve in the above substances. In addition, there is no particular restriction on the lower limit of the amount of harmful byproducts, but even with careful manufacturing, it is usually 0.2 to 0.8
% contamination is unavoidable. The structure and origin of this harmful byproduct are not fully clear, but when we measured the molecular weight of components separated by liquid chromatography using gel permeation chromatography, we found that a group of compounds with molecular weights between 700 and 1200 were found. It was hot. It is also assumed that the cause of this phenomenon is influenced by the PH, mixing state, temperature, etc. at each stage of the production of the photosensitive compound and the preparation of the resist composition in a complex manner. Generally, as mentioned above, the reaction is carried out by adding a deoxidizing agent (basic substance) to the raw material solution.
At this time, if the mixing condition is insufficient, the local pH
It is presumed that abnormal reactions progress locally due to bias toward basicity, accumulation of reaction heat, or both, contributing to the production of harmful byproducts. In addition, if the conditions at each stage from the manufacture of PAC-4 to the preparation of the resist composition locally deviate from the overall conditions, there is a possibility that harmful by-products may be generated, resulting in local abnormal reactions. It is necessary to pay attention to Furthermore, the temperature and time of each step are thought to have an influence on the abnormal reaction, and it is generally better to perform the treatment at a lower temperature even if the treatment time is longer. Liquid chromatography analysis of this harmful byproduct
Not only the state of PAC-4 produced by the above reaction but also the resist composition can be analyzed without interference when the coating film forming material is a novolak resin. Alternatively, analysis can be performed by separating the coating film forming material and PAC-4 using a solvent such as methanol in which PAC-4 is poorly soluble and which dissolves the coating film forming material. The coating film forming materials used in the present invention include novolac resin obtained by condensing a phenol derivative and an aldehyde derivative, polyvinyl alcohol, a copolymer of styrene and acrylic acid, a copolymer with an alkyl methacrylate ester, etc. Examples include alkali-soluble coating-forming materials. Among these, the use of novolac resins is preferable since they have good performance as positive photoresists. In addition, as a solvent, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ester solvents such as butyl acetate and amyl acetate, or highly polar solvents such as dimethyl formamide and dimethyl sulfoxide solvent or a mixed solvent of these,
Alternatively, examples include those to which aromatic hydrocarbons are further added. The composition ratio of the components in the positive photoresist composition of the present invention is as follows: PAC-4 1 to 20% by weight Coating film forming material 2 to 40% by weight Solvent 50 to 95% by weight Preferably, PAC-4 3 to 15% by weight % Paint film forming material 6-40% by weight Solvent 50-80% by weight. These numerical values are not strict as long as there is no problem in applying the positive photoresist composition. In terms of the performance of a positive photoresist composition, it is preferable to have a large amount of PAC-4;
If a large amount of -4 is used, more harmful by-products are likely to be mixed in, so more care must be taken to control harmful by-products. [Examples] Hereinafter, the present invention will be specifically explained using Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Synthesis Examples 1 to 3 24.6 g (0.1 mol) of 2,3,4,4'-tetrahydroxybenzophenone and 83.3 g of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride
(0.31 mol) was dissolved in a mixed solvent of 300 ml of dioxane and 80 ml of N-methylpyrrolidone, and 32 g of triethylamine was prepared under the temperature and stirring conditions shown in Table 1 below.
was added to carry out the reaction. After filtering out the by-produced triethylamine hydrochloride, the reaction solution was diluted with water from Step 2 to precipitate.
PAC-4 was collected by filtration and vacuum dried under the conditions shown in Table 1 below. The amount of harmful by-products in the obtained PAC-4 was as shown in Table 1 below.

〔Effect of the invention〕

According to the present invention, when a positive photoresist composition is stored for a long time, PAC-4 that has been dissolved once
It is possible to eliminate the problem of poor coating properties due to re-precipitation of.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a liquid chromatograph of a quinonediazide-based photosensitive compound in the present invention. In FIG. 1, 1 is a peak indicating a 4-substituted product;
2 is a peak indicating a quinonediazide compound in which two hydroxyl groups have been substituted to form a sulfonic acid ester, and 3 is a peak group indicating harmful byproducts, which is 0.75 to 0.9 times the retention time of the 4-substituted product peak. This is a group of peaks corresponding to the retention time of .

Claims (1)

[Claims] 1. In producing a positive photoresist composition using a quinonediazide-based photosensitive compound synthesized from tetrahydroxybenzophenone and naphthoquinonediazide sulfonyl chloride, (a) the photosensitive compound; photosensitive compound,
Analysis conditions for a composition containing a novolac resin and a solvent: Column: Fully porous silica gel with chemically bonded octadecylsilane Eluent: Acetonitrile/water/acetic acid (volume ratio
55/43/2) Detection: Analyzed by liquid chromatography using ultraviolet absorbance analysis (wavelength 254 nm). A photosensitive compound in which the area of a peak having a retention time 0.75 to 0.9 times the retention time of the peak of the sulfonic acid ester obtained by the reaction is 3% or less of the total area of all peaks due to the photosensitive compound, or , a method for producing a positive photoresist characterized by selecting a composition containing the same.