JPS62229140A - Photosensitive composition - Google Patents

Abstract

PURPOSE:To permit alkaline development and to improve heat resistance by constituting the titled compsn. with an alkali soluble resin and sensitizing agent as essential components and using a copolymer having specific three repeating units as the alkali soluble resin. CONSTITUTION:The alkali soluble resin and sensitizing agent are used as the essential components. The copolymer consisting of the repeating unit expressed by formula I, the repeating unit expressed by formula II and the repeating unit consisting of the compd. having an ethylenic unsatd. group is used as the alkali soluble resin. In formulas, at least one of R1-R5, R6-R10 among R1-R5 and R6-R10 respectively is an OH group and the remaining groups denote hydrogen, alkyl group, halogen group, nitro group and cyano group of 1-5C, alkoxyl group, allyl group, hydroxymethyl group, chloromethyl group and dialkylaminomethyl group of 1-5C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a photosensitive composition, and more particularly to a photosensitive composition that can be developed with alkali and has excellent heat resistance.

(Prior Art) Typical photosensitive compositions that can be developed with alkali include resins having a phenol skeleton, such as novolac resins, negative types in which exposed areas are insoluble in alkali due to a combination of polyvinylphenol and azide compounds, and naphthoquinone diazide. There is a positive type in which the exposed area becomes alkali-soluble when combined with a compound having a group or a benzoquinonediazide group, and these are used, for example, for photoresists and PS plates.

In recent years, the density of semiconductor devices has been increasing, and along with this, requirements for photoresists for semiconductors have been raised in many areas such as resolution, dry etching resistance, and heat resistance to enable microfabrication. There is. Dry etching has recently been used as a method for processing workpieces such as aluminum and Si02 for miniaturization.
It is known that during this dry etching, the resistance of the resist is greatly influenced by the temperature conditions of heating and drying, and that the higher the drying temperature, the better the dry etching resistance. However, conventional positive resists using novolak resin or polyvinylphenol, and negative resists using polyvinylphenol, have the disadvantage that patterns flow when heated to high temperatures during heating and drying after exposure and development. Heat resistance is determined by the combination of resin and photosensitive agent, and it has been known that the higher the flow temperature or softening point of the resin itself, the less likely pattern flow will occur. However, if the molecular weight of the novolac resin is increased in order to raise its softening point, it may become insoluble in solvents or difficult to be developed with alkali. Regarding polyvinylphenol, those whose molecular weight is increased to such an extent that pattern flow does not occur have problems such as resolution.

(Problems to be Solved by the Invention) An object of the present invention is to solve the problems described in item 2 and to provide a photosensitive composition that is capable of alkaline development and has excellent heat resistance.

[Structure of the invention] (Means and effects for solving the problems) In the photosensitive composition of the present invention, the photosensitive composition mainly contains an alkali-soluble resin and a photosensitizer, and the alkali-soluble resin has the formula: : A repeating unit indicated by .

A repeating unit consisting of a repeating unit represented by the formula and a compound having an ethylenically unsaturated group (wherein, R2 to R, and R6 to R.

In each of R1 to R 5 + R6 to Ri
At least one of O is an OH group, and the remaining groups are hydrogen,
Alkyl group having 1 to 5 carbon atoms, halogen group, 2) and 2) group,
cyano group, alkoxyl group having 1 to 5 carbon atoms, allyl group,
Represents a hydroxymethyl group, chloromethyl group, or dialkylaminomethyl group. ) is characterized in that it consists of a copolymer containing three types of repeating centers.

The photosensitive composition of the present invention is composed mainly of an alkali-soluble resin and a photosensitizer, of which the alkali-soluble resin is a copolymer containing three repeating units described below, and a random copolymer. , or a block copolymer.

First, the first repeating unit is a hydroxy-α-methylstyrene derivative represented by formula (I). Specific examples of this derivative include 4-hydroxy-α-methylstyrene, 3-hydroxy-α-methylstyrene, 3-methyl-
4-hydroxy-α-methylstyrene, 2-chloro-4
-Hydroxy-α-methylstyrene and the like.

Next, the second repeating unit is a hydroxyphenylmaleimide derivative represented by formula (TI). Specific examples of this derivative include 4-hydroxyphenylmaleimide, 3
-hydroxyphenylmaleimide, 2-hydroxyphenylmaleimide, 3-methyl-4-hydroxyphenylmaleimide, 3-methoxy-4-hydroxyphenylmaleimide, and the like.

In each of R1 to R5 in the first repeating unit and R6 to RII1+ in the second repeating unit, substituents can be introduced after polymerization, such as an acetyl group, an allyl group, a chloro group, a hydroxymethyl group, etc. can be introduced after polymerization.

This polymerization is carried out by cationic polymerization using heat or an acid catalyst.

Furthermore, the third repeating unit is a compound having an ethylenically unsaturated group. Specific examples of this compound include styrene and styrene derivatives; unsaturated carboxylic acids; and esters of unsaturated carboxylic acids and aliphatic hydroxy compounds or aromatic hydroxy compounds.

Examples of styrene derivatives include 4-methylstyrene, 3-methylstyrene, 3,5-dimethylstyrene, 2
-chloro-4-methylstyrene, 4-ethylstyrene,
Examples include 3-ethylstyrene, α-methylstyrene, 4-methyl-α-methylstyrene, and the like.

As unsaturated carboxylic acids, mention may be made, for example, of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid.

As aliphatic hydroxy compounds, mention may be made, for example, of methanol, ethanol, propatool and butanol.

As aromatic hydroxy compounds, mention may be made, for example, of phenol, hydroquinone, catechol, resorcinol, phloroglucinol and pyrogallol.

Examples of esters of unsaturated carboxylic acids and aliphatic hydroxy compounds include acrylic acid methyl ester, acrylic acid ethyl ester, acrylic acid n-propyl ester, acrylic acid 1so-propyl ester, acrylic acid n-butyl ester, acrylic acid Acrylic acid esters such as tert-butyl ester; methacrylic acid methyl ester, methacrylic acid ethyl ester, methacrylic acid n
-Methacrylic acid esters such as propyl ester, 1so-propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate; methyl itaconate, ethyl itaconate, n-propyl itaconate, itaconic acid 1
itaconic acid esters such as so-propyl ester, itaconic acid n-butyl ester, itaconic acid tert-butyl ester; Examples include crotonic acid esters such as crotonic acid n-butyl ester and crotonic acid tert-butyl ester.

Examples of esters of unsaturated carboxylic acids and aromatic hydroxy compounds include phenyl acrylate, methylphenyl acrylate, ethylphenyl acrylate, phenyl methacrylate, methylphenyl methacrylate, ethylphenyl methacrylate, phenyl itaconate, and itacon. Mention may be made of methylphenyl acid, butylphenyl itaconate, phenyl crotonate, methylphenyl crotonate, and butylphenyl crotonate.

In the photosensitive composition of the present invention, the copolymer which is one of the main components is an alkali-soluble resin, when expressed as a ratio of the number of repeating units, the total number of repeating units constituting the copolymer is 1
00, repeating unit (I), repeating unit (
II) is a copolymer containing 5 or more of each of repeating units (m), and the weight average molecular weight of this copolymer is 50
The copolymer has a molecular weight of 0 to 500,000, preferably 10,000 to 60,000, especially from the viewpoint of solubility in alkali.This copolymer has a high glass transition point and is therefore unlikely to cause pattern flow.

The photosensitizer used in the present invention is not particularly limited as long as it is generally known as a photosensitizer. Examples of the photosensitizer include naphthoquinone azide compounds and azide compounds. Examples of the naphthoquinone azide compound include 1,2-su7toquinone-2-diazide-
Examples of sulfonic acid esters synthesized from 5-sulfonic acid chloride and a compound having a phenolic hydroxyl group include, for example, the compound having a phenolic hydroxyl group.
3,4.5-)rihydroxybenzoic acid ethyl ester,
2,3.4-trihydroxybenzophenone, 2,4,
Examples include 2°,4'-tetrahydroxybenzophenone, quercetin, morin alizarin, quinizarin, and purpurin. In addition, examples of azide compounds include 3,3°-diazidiphenylsulfone, 2-methoxy-4°-azidochalcone, 1-(p-azidophenyl)-4-(2-
furyl)-1,3-butadiene. Among these, it is necessary to have solubility in a solvent and sensitivity to the wavelength of the light source of the exposure apparatus. Currently, widely used steppers use a 436 nm light source, so bis(l,
2-naphthoquinone-2-diazide-5-sulfonic acid)-
2,3,4-)lyhydroxybenzophenone ester,
1-(p-azidophenyl)-4-(2-furyl)-1
, 3-butadiene and the like are preferred.

These azide compounds may be used singly or in a mixed system of two inserts.

The photosensitive composition of the present invention contains 5 to 5 parts by weight of the above-mentioned photosensitive agent per 100 parts by weight of the copolymer which is the alkali-soluble resin.
0 parts by weight.

A specific example of the use of the photosensitive composition of the present invention is as follows:
The photosensitive composition is dissolved in a solvent such as cyclohexanone, ethyl cellosolve acetate, or methyl ethyl ketone, and then applied by spin coating onto a support such as a silicon wafer, and dried (50°C to 180°C, preferably). After 30 seconds to 90 minutes (preferably 1 minute to 60 minutes) at 70 DEG C. to 120 DEG C. to 120 DEG C., exposure to ultraviolet rays is carried out in accordance with a conventional method, for example, by exposing light in an appropriate wavelength range through a mask. Development is then carried out using a suitable alkaline solution. then io
o'c~200°C, preferably 120°C~180'Ct
, 30 seconds to 120 minutes, preferably 1 minute to 90 minutes. The support, for example a silicon wafer, is processed by conventional methods such as etching and metallurgy.

(Example) Example = 1 As an alkali-soluble resin, 4-hydroxy-α-methylstyrene 40 parts by weight 4
16 g of a copolymer (weight average molecular weight 60,000) consisting of 20 parts by weight of 1 liter of hydroxyphenylmaleimide and 40 parts by weight of styrene; 1.
A photosensitive solution consisting of 4 g of 2-naphthoquinone-2-diazide-5-sulfonic acid ester (esterification rate = 2%) and 70 g of cyclohexanone as a solvent was prepared and applied onto a silicon wafer substrate using a spinner. This was dried on a hot plate (90°C, 5 minutes) to a film thickness of 1.5I.
A photoresist film was formed on the substrate, and then the substrate was exposed to light of 250 W for 90 seconds using an ultra-high pressure mercury lamp using a quartz mask. Furthermore, after developing with a 0.4% tetramethylammonium hydroxide aqueous solution, washing with water,
When dried on a hot plate (140° C., 5 minutes), a pattern consisting of one line and a space was formed.

Heating the substrate with the pattern formed on it on a hot plate (1
There was no change in the pattern shape even after 60'0130 minutes).

Example 2 4-hydroxy-α-methylstyrene 40tt as alkali-soluble resin
M4-Hydroxyphenylmaleimide 10 parts by weight Styrene 35 parts by weight Acrylonitrile 16 g of a copolymer (weight average molecular weight 20,000) consisting of 15 parts by weight, 55 g of cyclohexanone as a solvent, 1.1% tetramethylammonium hydro as a developer A photosensitizer was prepared in the same manner as in Example 1 except that an oxide aqueous solution was used,
When further patterning was performed, a pattern consisting of 1 μm lines and spaces was formed. The patterned substrate was heated on a hot plate I- (160'C).
! There was no change in the pattern shape even after 30 minutes).

Comparative Example 16 g of cresol novolac resin (weight average molecular weight 5,000) was used as an alkali-soluble resin, and 2 g was used as a photosensitizer.
, 3.4-) 1,2-naphthoquinone-2-diazide-5-sulfonic acid ester of lyhydroxybenzophenone (
A photosensitive solution was prepared consisting of 4 g of esterification rate (2% esterification) and 20 g of cyclohexanone as a solvent, and this was applied to the silicone substrate -1- using a spinner.

Then hot plate A photoresist film having a film thickness of 1.5 μm was formed.

Next, this substrate was exposed to light for 90 seconds using a 250 W ultra-high pressure mercury lamp using a quartz mask. After further developing with a 2 to 3% cosone aqueous solution, it was washed with water and dried on a hot plate-1 (100'0).

After 5 minutes), a pattern consisting of 2- lines and spaces was formed. The substrate on which the pattern has been formed is heated with hot plate 1 (110'0).

5 minutes), a change in the shape of the pattern was observed.

(Effects of the Invention) As is clear from the explanation below, the photosensitive composition of the present invention does not cause the formed pattern to flow during exposure, development, and heat drying even when subjected to high temperature treatment. ,
It has excellent heat resistance and is of great industrial value.

Claims (1)

[Scope of Claims] In a photosensitive composition containing an alkali-soluble resin and a photosensitizer as main components, the alkali-soluble resin is a repeating compound represented by the formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) Unit, formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... (II) A repeating unit consisting of a repeating unit represented by and a compound having an ethylenically unsaturated group (however, in the formula, R_1 to R_5 and R_6 to R_1_
0, R_1 to R_5, R_6 to R_
At least one of 1_0 is an OH group, and the remaining groups are hydrogen, an alkyl group having 1 to 5 carbon atoms, a halogen group, a nitro group, a cyano group, an alkoxyl group having 1 to 5 carbon atoms, an allyl group, and a hydroxymethyl group. , chloromethyl group, or dialkylaminomethyl group. ) A photosensitive composition characterized in that it is a copolymer consisting of the above three types of repeating units.