JPH01154048A - Photosensitive composition - Google Patents

Abstract

PURPOSE:To form a resist pattern with a fine and good cross-sectional shape by incorporating a specified alkali soluble resin and a photosensitive agent in the photosensitive composition. CONSTITUTION:The photosensitive composition contains the alkali soluble resin which has >=50% transmissivity to the light having a wavelength of 248nm at the time of forming a film with 1.0mum thickness, and the photosensitive agent capable of being sensitized with the light having the wavelength of 248nm. The alkali soluble resin is exemplified by, for example, isopropenyl phenol, polyvinyl phenol or the polyvinyl phenol with an introduced silicon compd. having an alkyl group, etc. contg. silicon atom substd. in a benzene nucleus. The photosensitive agent is not specified, so far as the agent is sensitized with the light having the wavelength of 248nm. The agent is exemplified by, for example, a naphthoquinone diazide compd. and an azide compd. Thus, when the photosensitive composition is applied on a substrate as a resist film, and then the resist film is exposed with KrF exima laser, as the light can sufficiently reach a position away from the surface of the resist film, the resist pattern with the good cross-sectional shape can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a photosensitive composition, and more particularly to a photosensitive composition that is exposed to a KrF excimer laser.

(Prior Art) In the manufacturing process of semiconductor devices such as LSIs, microfabrication technology using photoetching is employed. This technology is
For example, a photoresist film is formed on a substrate such as a silicon single crystal wafer by a spin coating method, and after this resist film is exposed, a resist pattern is formed by processing such as development and rinsing. This is a method of etching the exposed wafer using an etching mask to create lines or windows with minute widths.

In the manufacture of the above-mentioned LSIs, as LSIs become more highly integrated, finer processing techniques are required. In response to these demands, attempts have been made to shorten the wavelength of the exposure light source. One such method is to use a K r F excimer laser as a light source. However, conventional photoresists absorb too much of the 248 na+ light from the KrF excimer laser, so the parts far away from the surface of the resist film (for example, the parts on the substrate side covered with the resist film)
The laser cannot reach the target sufficiently. As a result, the cross-sectional shape of the resist pattern after development becomes triangular, so that when the resist pattern is used as an etching mask for a substrate, etc., there is a problem that an etching pattern faithful to the pattern cannot be transferred to the substrate, etc.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems.
The object of the present invention is to provide a photosensitive composition that can sufficiently reach parts distant from the surface when exposed to light using an excimer laser, and can form a resist pattern with a good cross-sectional shape.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides that when a film with a thickness of 1.0 μm is formed, 248
This is a photosensitive composition characterized by containing an alkali-soluble resin having a transmittance of 50% or more to light of 248 nm and a photosensitizer that is sensitive to light of 248 ni.

The reason for limiting the transmittance of 248 nm light to the above value when forming a 1.0 μm thick film of the alkali-soluble resin is that if the transmittance is less than 50%, the KrF excimer laser will not penetrate into the resist film. This is because during exposure, light cannot sufficiently reach the back surface side portion away from the front surface, making it difficult to form a good pattern with a trapezoidal cross section.

Examples of such alkali-soluble resins include isopropenylphenol, polyvinylphenol, polyvinylphenol with a silicon compound such as an alkyl group containing silicon introduced into the benzene nucleus, vinylphenol and styrene, acrylonitrile, methyl methacrylate, Examples include methacrylate copolymers.

The photosensitizer is not particularly limited as long as it is sensitive to 248 na+ light, and for example, naphthoquinone diazide compounds and azide compounds can be used. Examples of naphthoquinone cyasito compounds include sulfonic acid esters synthesized from 1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride and a compound having a phenolic hydroxyl group. Examples of the compound having a phenolic hydroxyl group used here include 3.
4.5-trihydroxybenzoic acid ethyl ester, 2.
R4-) lyhydroxybenzophenone, 2.4.2-.
4--Tetrahydroxybenzophenone, 2.3.4-
-Tetrahydroxybenzophenone, quercetin, morin alizarin, xyrizarin, purpurin, etc. can be mentioned. Examples of the azide compounds include 3.
3-1 diazidiphenyl sulfone, 2-methoxy-4
'-azidochalcone, 1-(p-azidophenyl)4-
(2-furyl)-1,3-butadiene and the like can be mentioned. Among these photosensitizers, bis(1,2-naphthoquinone-2-diazide-5-sulfonic acid)-2,3,4-trihydroxybenzophenone ester is particularly used as a naphthoquinone diazide compound, and 1 as an azide compound.
-(p-azidophenyl)-4-(2-furyl)-1,
Preferably, 3-butadiene is used.

The above-mentioned photosensitizer is the naphthoquinone diazide compound mentioned above,
In addition to the azide compound, a diazo compound represented by the following general formula (1) can be used.

However, R1 and R2 in the formula are substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, substituted or unsubstituted aryl groups, substituted or unsubstituted alkyl groups having 1 to 2 o carbon atoms containing silicon, or silicon. Indicates a substituted or unsubstituted aryl group.

Examples of the substituent to the alkyl group as R11R2 introduced into the above general formula (1) include a halogen group, an unsaturated group, a carbonyl group, a carboxyl group, a nitrile group, an ether group, a thioether group, a thioester group, etc. Can be done. Substituents to the aryl group as R1 and R2 introduced into the general formula (I) include, for example, a halogen group, an unsaturated group, a carbonyl group, a carboxyl group, a nitrile group, an ether group, a thioether group, a thioester group, and an alkyl group. basis,
Examples include alkoxy groups. Such a general formula (
Examples of the photosensitizers in which an unsubstituted or substituted alkyl group or an unsubstituted or substituted aryl group having 1 to 20 carbon atoms is introduced into R1 and R2 of I) include those shown in Table 1 below,
Alternatively, a reaction product of a compound shown in Table 1 and a phenol resin can be mentioned. In addition, R1 of the same general formula (I),
Examples of photosensitizers in which a silicon-containing unsubstituted or substituted alkyl group having 1 to 20 carbon atoms or a silicon-containing unsubstituted or substituted aryl group are introduced into R2 include those shown in Table 2 below. .

The amount of the photosensitive agent to be blended with the alkali-soluble resin is preferably 1 to 200 parts by weight per 100 parts by weight of the resin. The reason for this is that if the amount of the photosensitizer is less than 1 part by weight, it will not be possible to maintain sufficient solubility between the exposed and unexposed areas after exposure;
If the amount exceeds 0 parts by weight, it will be difficult to prepare a photosensitive composition in a solution state, and the applicability to substrates etc. may be impaired.

In addition to the alkali-soluble resin and photosensitizer, the photosensitive composition of the present invention may optionally contain a sensitizer, a dye, a surfactant, and a polymer for modifying the coating film (e.g., epoxy resin, polymethyl methacrylate). (resin, propylene oxide-ethylene oxide copolymer, polystyrene, silicone ladder polymer, etc.) may also be blended.

Next, a process for forming a resist pattern using the photosensitive composition of the present invention will be explained.

First, a resist solution consisting of the photosensitive composition of the present invention dissolved in an organic solvent is applied onto a substrate by a spin coating method or a dipping method.
A resist film is formed by drying at 120°C. Examples of the substrate used here include a single silicon single crystal wafer, the same wafer with various coatings such as an insulating film and a conductive film deposited on its surface, or a mask blank. Examples of the organic solvent include ketone solvents such as cyclohexane, acetone, methyl ethyl ketone, and methyl isobutyl ketone, cellosolve solvents such as methyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, and ester solvents such as ethyl acetate, butyl acetate, and isoamyl acetate. A solvent or a mixed solvent thereof is preferred.

Next, the resist film is exposed to KrF excimer laser having a wavelength of 248 ns through a mask having a desired pattern, and then developed with an alkaline aqueous solution to form a desired resist pattern.

Examples of the alkaline aqueous solution used here include a tetramethylammonium hydroxide aqueous solution.

(Function) The photosensitive composition of the present invention comprises an alkali-soluble resin that has a transmittance of 50% or more to 248 ns light when a film with a thickness of 1.0 μm is formed, and a photosensitizer that is sensitive to 248 rv light. Because of this structure, when a substrate or the like is coated as a resist film and then exposed with a KrF excimer laser, light can sufficiently reach not only the surface but also the portion on the substrate side. As a result, by development after exposure, it is possible to form a resist pattern having a good pattern profile in which the widths of the top surface and the bottom surface are approximately the same. Furthermore, development with an alkaline aqueous solution becomes possible. Therefore, by etching a substrate or the like using the resist pattern as an etching mask, a pattern faithful to the resist pattern can be transferred onto the substrate or the like. Furthermore, if at least one of the alkali-soluble resin and the photosensitive agent contains silicon, a resist pattern with excellent oxygen reactive etching resistance (oxygen RIE resistance) can be formed by exposure and development.

(Example of the invention) Examples of the present invention will be described in detail below.

Examples 1 to 9 and Comparative Examples As shown in Table 3 below, an alkali-soluble resin and a photosensitizer having a predetermined transmittance of 248 rv light when formed into a 1.0 μm resin film were prepared using cellosolve acetate. and filtered through a 0.2 μm filter to prepare 10 kinds of photosensitive compositions.

Next, each of the photosensitive compositions was applied onto a silicon single crystal wafer using a spinner and dried at 80°C to a thickness of 0.8 μm.
A resist film of m was formed. After applying pattern exposure to these resist films using a reduction projection exposure device using a KrF excimer laser as a light source, they were immersed for 30 seconds in a tetramethylammonium hydroxide (TMAH) aqueous solution having the concentrations shown in Table 3, and developed. was applied and further washed with water to form a resist pattern.

For the resist patterns formed from the photosensitive compositions of Examples 1 to 9 and Comparative Examples, line and space widths, pattern shapes, and film loss of the resist patterns after development were investigated using an electron microscope. . The results are also listed in Table 3 below.

As is clear from Table 3, applying the resist film using the photosensitive composition of the present invention, exposing it to KrF excimer laser,
It can be seen that by performing development with a TMAH aqueous solution, a resist pattern having a good shape with fine lines and spaces and without film loss can be formed. On the other hand, the resist pattern formed by the same process using the photosensitive composition of the comparative example is difficult to miniaturize, has a triangular cross-sectional shape, and has a thickness of 0.4 μm, half of the initial resist film thickness. It can be seen that film thinning occurs.

[Effects of the Invention] As described in detail above, according to the present invention, when a resist film is coated on a substrate or the like and then exposed with a KrF excimer laser, it is possible to allow light to sufficiently reach parts far from the surface. It is possible to provide a photosensitive composition that can form a resist pattern having a fine and good cross-sectional shape and can be effectively used in a photoetching process for manufacturing highly integrated semiconductor devices and the like.

CH.

Claims (4)

[Claims] (1), 248 nm when forming a film with a thickness of 1.0 μm
1. A photosensitive composition comprising an alkali-soluble resin having a transmittance of 50% or more to light of 248 nm and a photosensitizer that is sensitive to light of 248 nm. (2) The photosensitive composition according to claim 1, wherein the alkali-soluble resin is a polymer having a skeleton of isopropenylphenol or vinylphenol. (3) The photosensitive composition according to claim 1, wherein the alkali-soluble resin is a copolymer of vinylphenol and styrene. (4) The photosensitive composition according to claim 1, wherein the photosensitizer is a diazo compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) However, R_1 and R_2 in the formula are substituted or unsubstituted alkyl groups with 1 to 20 carbon atoms, substituted or unsubstituted aryl groups, and silicon-containing 1 carbon atoms. ~20 substituted or unsubstituted alkyl groups or silicon-containing substituted or unsubstituted aryl groups.