JPH01145651A - Pattern forming method - Google Patents

Abstract

PURPOSE:To make it possible to form a pattern by dry development by carrying out development with radiation in place of development with chemicals. CONSTITUTION:A resist film is formed with a radiation-sensitive compsn. contg. a radiation-disintegrable polymer (a) and a compd. (b) which reacts with the polymer (a) on being exposed and is sublimed or vaporized by heat treatment. The resist film is patternwisely exposed, the unreacted compd. (b) is removed by heat treatment and radiation is projected on the entire surface of the resist film to carry out development. The rate of disintegration and vaporization of the polymer (a) in the exposed part in which the compd. (b) has been fixed and the polymer (a) has been cross-linked is made lower than that in the unexposed part in which the compd. (b) has been removed in the unreacted state, so a negative pattern can be formed by dry development.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method of forming a pattern in a semiconductor manufacturing process using lithography 2 technology by performing a dry development process using radiation without performing a development process using chemicals.

[Technical Background and Problems] In the semiconductor manufacturing process lithographic technology, a method called wet development using chemicals such as organic solvents is commonly used as a resist development method. However, wet development poses a problem of reduced resolution due to swelling and contraction of the resist polymer during development.

There are also problems with wet development that need to be solved in terms of process automation and controllability. In view of the effects of chemicals on the human body and waste disposal, there is an increasing demand for dry development processes that do not require development processing using chemicals. Under these circumstances, several dry development processes have been reported in recent years. Typical examples thereof include irradiation development in which the resist polymer in the exposed area is vaporized and developed simultaneously with pattern exposure, and plasma development in which development is performed by plasma treatment after pattern exposure. However, none of these methods have been put into practical use at this stage, and the development of a new dry development process has been desired.

[Object of the Invention] The object of the present invention is to provide a novel method for forming a pattern by dry development, in which a development process is performed using radiation without the conventional development process using chemicals. be.

[Disclosure of the Invention] It is known that p-benzoquinone reacts with a polymer having a lower alkyl ester group in its polymer structure, such as polymethylmethacrylic acid, upon exposure to light, resulting in fixation of ρ-benzoquinone and crosslinking reaction of the polymer. It is well known that an azide compound photoreacts with a polymer such as polymethyl methacrylic acid to cause immobilization of the azide compound and a polymer→crosslinking reaction. Examples have been reported in which negative patterns were formed by chemical treatment using these reactions; The present inventors investigated whether or not it has the effect of suppressing the decomposition and vaporization of a radiolytic polymer when irradiated with radiation, and investigated the possibility of a dry development and imaging process using radiation. A resist film formed from a radiation-sensitive composition containing a radiation-decomposable polymer (a) and a compound (b) that reacts with the polymer upon exposure and has the property of sublimating or vaporizing upon heat treatment was exposed in a pattern. After that, the unreacted compound (b) was removed by heat treatment, and then the entire surface of the resist film was developed by irradiating radiation, and the compound '!IJ (b) was fixed during pattern exposure. , the decomposition and vaporization rate of the radiation-degradable polymer is lower in the subsequent development treatment by radiation irradiation, and dry development We have discovered that it is possible to form a negative pattern by

The present invention has been made based on this knowledge.

That is, the present invention is made of a radiation-sensitive composition containing a radiation-decomposable polymer (a) and a compound (b) which is a compound that reacts with the polymer upon exposure and has the property of sublimating or vaporizing upon heat treatment. The present invention provides a pattern forming method characterized by exposing a resist film to pattern light, subjecting it to heat treatment, and then irradiating the entire surface of the resist film with radiation for development.

The radiation decomposable polymers used in the pattern forming method according to the present invention include polymethyl methacrylate, polyethyl methacrylate, poly n-butyl methacrylate,
poly(methyl methacrylate-methacrylic acid) copolymer,
Examples include polymethylene dimethyl malonate, polydimethyl itaconate, poly-α-methylstyrene, poly(1-butene-sulfone) copolymer, and the like. Representative examples of the compound (b) include p-benzoquinone or 4.
Examples include 4°-diazidiphenylmethane, 4,4°-diazidiphenyl disulfide, and the above p-
The appropriate amount of penzoquinone to be used is 5 to 5 (hvt%) based on the polymer (a) above; if it is less than 5wt%, the effect of suppressing the decomposition and vaporization of p-benzoquinone will decrease, and good contrast will not be obtained. First, if the amount exceeds sowt%, p-benzoquinone will precipitate during resist film formation (coating), which is not preferable. An amount of 5 to 50 wt% is appropriate for the amount of 50 v.
If the amount exceeds t%, unreacted 4,4
It becomes difficult to remove the °-diazidiphenyl compound.

The light source for pattern exposure of the resist film may be any light source that can cause the compound (b) to react, and specific examples include electron beams, X-rays, deep ultraviolet rays, and the like. Further, by adding a sensitizer, the compound (b) can be almost completely removed from the polymer film by heating to usually 100° C. or higher using a pattern with ultraviolet rays. In this case, when an azide compound is used, it is not necessarily necessary to completely remove the azide compound in the unexposed area.

The removal time can be shortened by performing the heat treatment under reduced pressure. Examples of the radiation source for the subsequent development process by irradiating the entire surface with radiation include electron beams, X-rays, and deep ultraviolet rays. At this time, the decomposition and vaporization time can be shortened by heating the resist coated substrate.

The pattern forming method according to the present invention provides a novel dry development process for radiation-sensitive resists.

EXAMPLES The present invention will be described below with reference to Examples of the present invention.

Practical Direction 1 A resist composition having the following composition was coated on a wafer to a thickness of 1 μm.

Polymethyl methacrylate 2g4.4°-Diazidiphenylmethane 0.8g dichloromethane
151 & then 60 using a far ultraviolet exposure device
After pattern exposure at an exposure dose of 0 riJ/cJ, 4,4°-diazidiphenylmethane was removed by a bundle reaction at 120°C for 1 hour in a vacuum heating dryer. The entire surface of the resist-coated substrate was irradiated with deep ultraviolet rays of 253.7 nl at a dose of 24 J/- while heating it to 130 DEG C., and a development process was performed by decomposition vaporization, resulting in a negative pattern with a line width of 1 .mu.m.

Example 2 When a process similar to that described in Example 1 was carried out using a resist composition having the composition shown below, a negative pattern with a line width of 1 μm was obtained.

Dimethyl polyitaconate 2g 4.4°-Diazidiphenylmethane 0.8g dichloromethane
15[L Example 3 A resist composition having the following composition was coated on a wafer to a thickness of 1 μm.

Polymethyl methacrylate 2g p-benzoquinone 0.8g dichloromethane 15n! .

Next, after pattern exposure to 250 nm deep ultraviolet rays at an exposure dose of 1312 nJ/-, 0.4 nmH was applied in a vacuum heating dryer.
p-benzoquinone was removed by a bundle reaction at 120° C. for 2 hours. Next, while heating the resist-coated substrate to 200°C, 253.7 nIl of deep ultraviolet rays was applied for 23.2 J.
When the entire surface was irradiated with an irradiation amount of /- and a development process was performed by decomposition vaporization, the decomposition and vaporization rate ratio between the exposed area and the unexposed area in pattern exposure was about 1=6, and a good negative pattern was obtained.

Example 4 When a process similar to that described in Example 3 was carried out using a resist composition with the following composition, the decomposition and vaporization rate ratio between the exposed area and the unexposed area in pattern exposure was approximately 1=6. A good negative pattern was obtained.

Claims (6)

[Claims] (1) A resist film formed from a radiation-sensitive composition containing a radiation-decomposable polymer (a) and a compound (b) which is a compound that reacts with the polymer upon exposure and has the property of sublimating or vaporizing upon heat treatment. A method for forming a pattern, which comprises exposing the resist film to a pattern, heat-treating the resist film, and then irradiating the entire surface of the resist film with radiation for development. (2) The pattern formation according to claim 1, wherein the radiodegradable polymer (a) has a group capable of reacting with an azide compound in its structure, and the compound (b) is an azide compound. Method. (3) A claim characterized in that the radiolyzable polymer (a) is a polymer having a group capable of reacting with p-benzoquinone in its structure, and the compound (b) is p-benzoquinone. Item 1. The pattern forming method according to item 1. (4) The p- contained in the radiodegradable polymer (a)
4. The pattern forming method according to claim 3, wherein the group capable of reacting with benzoquinone is a lower alkyl ester group. (5) The pattern forming method according to claim 2, wherein the azide compound is 4,4'-diazidiphenylmethane. (6) A radiation-sensitive radiation-sensitive material for use in a pattern forming method containing a radiation-decomposable polymer (a) and a compound (b) which is a compound that reacts with the polymer upon exposure and has the property of sublimating or vaporizing upon heat treatment. Composition.