JPS6370846A - Silicon-containing negative type photoresist composition - Google Patents

Abstract

PURPOSE:To obtain a photoresist compsn. which can form fine patterns with extremely high sensitivity to UV rays and has excellent O2RIE resistance by incorporating a styrene polymer contg. silicon atoms and bisazide compd. as a sensitizing agent into said compsn. CONSTITUTION:The substituent R in the repeating unit expressed by the formula I denotes a lower alkyl group of 1-6C. A more specific example of the styrene monomer having the silicon atoms is preferably a trimethyl silyl styrene as said monomer is easily available. The polymer contg. the silicon atoms may be a copolymer of >=1 kinds of the monomers and an ethylenic unsatd. compd. which can be copolymerized with said monomers in addition to the homopolymers of the monomers or the copolymers thereof. The bisazide compd. which is the 2nd component is preferably the compd. expressed by the formula II. The compsn. which has the high sensitivity to light, exhibits the high resistance to oxygen plasma as well and is useful foe ultrafine working of semiconductor elements, magnetic bubble elements, etc., is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a photoresist composition that can be used for manufacturing semiconductor devices, magnetic bubble devices, and the like.

[Conventional technology]

In the manufacture of semiconductor integrated circuits, magnetic bubble elements, etc., the density has increased in recent years, and thin film microfabrication technology has become an extremely important elemental technology.

Recently, dry etching with high processing accuracy has been used in place of conventional wet etching, and therefore a method of obtaining a high aspect ratio pattern that is thicker than the pattern width has become necessary. In addition, in optical lithography, it is difficult to obtain sufficient resolution when using a thick resist layer due to reflection from the substrate, and in electron beam lithography, due to scattering of electrons.On the other hand, in order to obtain a high-resolution resist pattern, The disadvantage of using a thin resist layer is that it does not have sufficient resistance to process the substrate during dry etching. Furthermore, in order to flatten the stepped portion of the surface to be processed, a resist layer having a certain thickness is required, and it is extremely difficult to form a fine pattern on such a resist layer. In order to solve these problems, there is a tendency for multilayer resists to be adopted.

One of the representative methods is the 3N resist method.

The three-layer resist method was first announced by J. Havas for the purpose of application to the lift-off process.
Journal of Vacuum Science and Technology (1979 by J. Moran).
J, Vacuum 5science and T
Since it was reported in Volume 16, page 1620 of ``Technology'', it has become a serious topic of discussion.

The three-layer resist consists of a flattening layer, an intermediate layer, and a patterning resist layer from the bottom, and the flattening layer is made of a polymer material with a thickness of 2 to 3 .mu.m, and is made of an ordinary photoresist material. At this time, the level difference on the substrate is smoothed. The middle class is 0□
This serves as a mask material during IIIE, and inorganic materials such as a silicon oxide film and a silicon nitride film are used. The process begins by exposing the upper resist to a light or electron beam and then developing it. The intermediate layer is dry-etched using the obtained resist pattern as a mask, and then the planarization layer is etched using the patterned intermediate layer as a mask.
! I? Etch by IH. With this method, a pattern with high resolution and high aspect ratio that is not affected by substrate steps can be realized.

However, such a method has the disadvantage that the process is complicated and long.

[Problem that the invention seeks to solve]

As a solution to these drawbacks, a two-layer resist method that requires a relatively small number of steps is attracting attention.

Since the 2N resist has a two-layer structure with the intermediate layer removed, the upper resist layer must also have the function of the intermediate layer. Therefore, 0. There is a need for a top resist material that is resistant to RIB.

O for upper layer resist for 2N resist! In addition to RIE resistance, characteristics such as high sensitivity and high resolution required for general single-layer resists are required, and various organometallic polymers have been proposed in an attempt to satisfy these characteristics. Organometallic polymers are O! During RIB, it reacts with oxygen plasma, forming a thin metal oxide layer on the surface, and this layer becomes O□R.
It is known to act as a barrier layer against IB. One method is to include silicon in the resist layer, and by performing 01 RIE, the organic components are incinerated and silicon oxide (Stow) remains, which reduces the resistance to 0! It becomes an R1E film, and dry development of the lower layer becomes possible.

An object of the present invention is to provide a photoresist composition that can form fine patterns with extremely high sensitivity to ultraviolet rays and has excellent resistance to 0tRIB.

[Means for solving problems]

The present invention provides a silicon-containing negative characterized by containing a styrenic polymer having a silicon atom containing a repeating unit represented by the general formula (wherein R represents a lower alkyl group) and a bisdiazide compound as an irradiant. type photoresist compositions.

The present invention will be explained in detail below.

The substituent R in the repeating unit represented by the above general formula used in the present invention represents a lower alkyl group having 1 to 6 carbon atoms, such as a methyl group, ethyl group, or propyl group, preferably an alkyl group having 4 or less carbon atoms. It is.

Specific examples of the styrene monomer having a silicon atom include trimethylsilylstyrene, triethylsilylstyrene, tripropylsilylstyrene, and the like. Among them, trimethylsilylstyrene is preferred because it is easily available.

The silicon atom-containing polymer used in the present invention is not only a single or copolymer of the above monomers, but also a copolymer of one or more of the above monomers and an ethylenically unsaturated compound copolymerized with these monomers. Specific examples of ethylenically unsaturated compounds that may be combined include acrylic acid and methacrylic acid derivatives, such as esters of acrylic acid and methacrylic acid such as methyl, ethyl, propyl, and glycidyl;
Styrenic FI bodies, such as styrene, vinyltoluene,
Examples include chloromethylstyrene, α-methylstyrene, vinyl acetate, methylvinyl ketone, N-vinylpyrrolidone, vinylpyridine, and the like.

The content of ethylenically unsaturated compounds in the above polymer *t
varies depending on the substituent R and the type of ethylenically unsaturated compound, but Ox R11! It can be adjusted as appropriate within a range that does not reduce resistance. Preferably 5 in the polymer
1 content ranges from about 4 to about 16% by weight.

Polymers used as negative resists generally have high sensitivity if they have a high molecular weight, but they have contradictory properties such as poor film-forming properties and reduced resolution due to swelling during development. Polymers with a molecular weight of over 1 million usually have high sensitivity. Resolution cannot be expected. On the other hand, reducing the molecular weight improves the resolution, but the sensitivity decreases in proportion to the molecular weight, which not only impairs practicality but also makes it difficult to form a uniform and firm film.

It is known that molecular weight distribution also affects resolution, and it is generally preferable to use a polymer with a dispersity of 4 or less, as a polymer with a smaller dispersity shows better resolution.

In view of the above points, the f (I average molecular weight of the styrenic polymer having silicon atoms represented by the above general formula is approximately 300
0 to 600,000, and the degree of dispersion is preferably 4 or less, particularly 2 or less. The method for obtaining a low dispersion polymer may be either a method of directly obtaining a monodisperse polymer by polymerization or a method using fractionation. do not have.

As a method for producing the styrenic polymer having a silicon atom represented by the above general formula, a conventional method of polymerizing an ethylenically unsaturated compound can be used, but from an industrial viewpoint, a radical polymerization method is preferable.

The bisazide compound which is the second component used in the present invention has the following general formula (II) (wherein R1 is -CH*-1-〇-1-CH-C)I-1
-N■N-l-5-1-SO□-1-CO-1-CHH
CCl3CO-CH-CH-1-CI = CI-C
It is a group represented by o-5H3, and R2 is a hydrogen atom, an alkyl group, or a halogen atom. ) are preferred, such as 3,3'-dichloro-4,4'-diazidodiphenylmethane, 4,4'-diazidiphenyl ether, 4,4'-diazidiphenylmethane, 4,4''- Diazido diphenyl sulfone, 3.3'-diazido diphenyl sulfone, 4.4''-diazidophenyl ketone, 4,4''-diazide chalcone, 216-di(4,-
azidobenzylidene) cyclohexanone, 2.6-di(4°-azidobenzylidene)-4-methylcyclohexanone, 2.6-di(4゛-azidobenzylidene)-
Examples include 4-hydroxycyclohexanone, particularly 4,4'-diazide chalcone, 2,6-di(4
°-azidobenzylidene)-4-methylcyclohexanone is preferred.

If the amount of these added is too small, the sensitivity to ultraviolet rays will be reduced, and if too much is added to the composition, the silicon content will be relatively reduced, resulting in insufficient 01RIE resistance, which is a problem. Therefore, the amount added is 0.5 to 3 to the polymer.
A range of 0 weight 2 is preferred.

In the above photoresist composition, a sensitizer, an additional resin, a plasticizer, a dye, etc. may be added to the extent that they do not adversely affect resist performance.

〔Effect of the invention〕

The negative photoresist composition of the present invention is highly sensitive to light and exhibits high resistance to oxygen plasma, and is useful for ultrafine processing of semiconductor devices and magnetic bubble devices. be.

(Examples) The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Reference Example 1 (Production of styrenic polymer containing silicon atoms) 191 g of trimethylsilylstyrene was placed in a three-day flask equipped with a nitrogen blowing tube, condenser, and thermometer.
(1,1 mol), chlormethystyrene 44 g (0,28
mole), benzoyl peroxide (BPO) 0.375g (0
, 11 mol%) and cyclohexane 1500 ml J
was charged, dissolved, and reacted at reflux temperature for 16 hours.

After the reaction was completed, the reaction solution was poured into a large amount of methanol to obtain a white powder polymer. After filtering off the 0 polymer, it was dissolved again in 300 ml of cyclohexane and poured into methanol.

The above operation was repeated twice to obtain a powdered polymer, which was then filtered and dried under reduced pressure. Mw=107.000, Mn=3
6,000SMi*/Mn=3 and 0 polymer 70
g was dissolved in 2200 l of methyl ethyl ketone, and methanol was added dropwise while stirring. When methanol 900+*1 was added dropwise, the mixture became cloudy. After it became cloudy, it was gently warmed to become transparent. - After allowing to stand day and night to separate the layers, the upper layer liquid was separated from the lower layer liquid using decanethisilane.

The lower solution a was dissolved in 50-1 cyclohexane, and then poured into a large amount of methanol to obtain a first flux polymer. Mw = 220.000, Mn = 8
9,000, Mw/Mn = 2.5. 200 ml of methanol was added to the decanty-silane solution to obtain a second fraction of polymer in the same manner. Mw-149,
000, Mn-99,000, Mw/Mn=1.5. Furthermore, 100 ml of methanol was added to the upper layer to obtain a third flux polymer.

M@=61,000, Mn=47.0001Mw/Mn
= 1.3.

Example 1 0.9 g of the second fraction of the trimethylsilylstyrene polymer synthesized in Reference Example 1 and 2.6-di(4'-
azidobenzylidene)-4-methylcyclohexanone 0
．． 09g was dissolved in toluene 17-1, thoroughly stirred, and then filtered through a 0.2μ filter to obtain a sample solution. This solution was spin-coated onto a Si substrate, dried in air at 80°C for 30 minutes, and then applied to a contact mask aligner.
Near ultraviolet irradiation was performed using

After developing for 1 minute using a THF/methanol (volume ratio: 45155) mixed solution, rinsing was performed for 1 minute using isopropyl alcohol. The amount of light irradiation that left 50% of the initial film thickness was 26 mj/c+s'', which had sufficient sensitivity for practical use.In addition, it sharply resolved lines and spaces of 1 μm, making it an excellent film in terms of resolution. But it was excellent.

Example 2 A containing novolac resin as the main component on a silicon wafer
Apply Z-1470 (Shipley) to a thickness of 1.2μ,
Heat treatment was performed at 200°C for 1 hour.

A resist solution similar to that used in Example 1 was spin-coated on this upper layer, and exposure and development were performed in the same manner as in Example 1 to obtain a resist pattern.

In order to examine the suitability of the obtained pattern as a dry etching mask for the underlying organic film, O.RIE was performed, and the pattern after etching was observed with a scanning electron microscope. Even after the etching of the exposed lower layer was completely completed, the thickness of the resist pattern remained almost unchanged, and the organic film of approximately 1 μm steel remained with a substantially vertical profile.

Claims (1)

[Claims] (1) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents a lower alkyl group.) A styrenic polymer containing a silicon atom containing a repeating unit and bisdiazide as a photosensitizer. Silicon-containing negative photoresist composition characterized by containing a compound