JPS61295548A - Negative type resist composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having a good sensitivity, and an excellent resolution and anti-dry etching properties, comparing with the conventional composition composed of a polyvinyl carbazole and a polystyrene by applying a mixture of a specific polymer and a bisazide compd. to a photoresist. CONSTITUTION:The titled composition is composed of the resist composed of 100pts.wt. the polymer having a repeating unit shown by the formula and a mol.wt. of 2,000-100X10<4> and 0.1-30pts.wt. the bisazide compd. When the titled composition has <2,000mol.wt., the glass transition point depresses, and the high polymer is not obtd. When the titled composition has >100X10<4>mol.wt., the coating and resolution properties are reduced. The molecular weight distribution of the used polymer is the monodisperse, or almost near to the monodisperse from the resolution point of view. If the compounding amount of the bisazide compd. to the titled composition is <0.1pts.wt., the effect of the addition is remarkably reduced. While if the prescribed amount is >30pts. wt., adversely, the depression of the resolution generates.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radiation curable composition, and more particularly to a negative resist composition suitable for forming fine/e-turns for manufacturing semiconductors, photomasks, etc. Regarding.

[Technical background of the invention and its problems]

In recent years, radiation (
Lithography (short wavelength ultraviolet rays, electron beams, X-rays, ion beams, etc.) is being put into practical use as a microfabrication technology. However, in microfabrication of approximately 0.5 μm or less, the lithography technology referred to below is indispensable. In these lithography techniques,
A fine resist pattern is formed using radiation, which is then masked and etched to transfer the pattern onto a substrate. The problem with etching is that conventional wet etching has a limit to transfer accuracy.
For submicron level 9m processing, it is essential to perform etching using a dry etching method with high transfer accuracy, mainly based on reactive ion dry etching. ↓It is essential for a radiation-curable composition used in submicron-level microfabrication to have high sensitivity to radiation, high resolution, and sufficient 1y-lighting resistance.

Practical resists used for this submicron-level microfabrication are sensitive to radiation.

In addition to high resolution, it is required to have sufficient resistance to dry etching, mainly reactive ion etching. Such high-sensitivity negative resists with sufficient resistance to dry etching include chlorine-containing resists such as chlorinated polystyrene and chloromethylated polystyrene made highly sensitive by chlorination or chloromethylation, and polyvinylcarnosol. , a negative resist with high sensitivity made by adding an azide compound to polystyrene has been reported (Japanese Unexamined Patent Publication No. 51736/1983). However, the former chlorine-containing resist is C-C
Although the presence of the t-bond effectively increases sensitivity, it has the problem that molecular weight and molecular weight distribution inevitably deteriorate when chloromethylated or chlorinated, which causes a decrease in resolution. ing. Furthermore, since it is difficult to control chloromethylation and chlorination reactions, differences in properties between synthetic lots tend to occur, making quality control difficult. On the other hand, the latter resist has the great advantage of being able to increase sensitivity through simple operations without deterioration of molecular weight and molecular weight distribution that occurs during chemical synthesis, as described above, but the efficiency of increasing sensitivity is lower than that of the former. It has the disadvantage that it has a lower sensitivity than a resist and cannot provide sufficient sensitivity.

[Purpose of the invention]

The present invention has been made to solve the above problems.
By using a mixture of a specific polymer and a bisazide compound that has been improved to increase its reactivity with reeds, especially with bisazide compounds, it is more effective than the conventional use of polyvinyl carnosol or polystyrene. The present invention aims to provide a practical high-performance negative resist composition that has much higher sensitivity, better resolution, and dry etching resistance.

[Summary of the invention]

The negative resist composition of the present invention has the following general formula: (wherein R1 to Rs may be the same or different and each represents an alkyl group having 1 to 10 carbon atoms or a hydrogen atom. However, this excludes the case where R1 to Rs are all hydrogen atoms.) and has a repeating unit of 2000 to 1oo
100 parts by weight of a polymer having a molecular weight of xio' and 0.1 to 30 parts by weight of a bisazi-P compound.

When a composition in which a bisazide compound is added to polystyrene or polyvinylcarnozole is irradiated, the bisazide compound is efficiently decomposed by the radiation, generating radicals or nono-radicals, which react with the polymer. It is estimated that an efficient crosslinking reaction proceeds. According to the present invention, if a styrenic polymer is improved to have a structure in which one or more hydrogen atoms in the phenyl slope are replaced with an alkyl group, the resulting polymer will have significantly higher reactivity with bisazide compounds. It was confirmed that cross-linking reaction occurs extremely efficiently by radiation.

It is thought that this increase in reactivity is intended to effectively increase the sensitivity of this resist. The cause of increased reactivity is
This is presumed to be due to the extremely high reactivity between the radicals generated by radiation from the bisazide compound, ie, nonoyl radicals, and the hydrogen of the alkyl group.

Polymers having repeating units represented by the general formula [A] used in the present invention include poly-2-methylstyrene, poly-3
-Methyl styrene/, poly-4-methyl styrene/, poly-
2-ethylstyrene, poly-4-ethylstyrene, poly-4-t-';'? Rustyrene, poly-4-isopropylstyrene, poly-3-t-butylstyrene, poly-4
-5ea-butylstyrene, poly')-4-neopentylstyrene, poly-2,5-dimethylstyrene, poly-3
, 4-dimethylstyrene, poly-2,4-dimethylstyrene, poly-3,5-dimethylstyrene, poly-2,5
--,,'ethylstyrene, yte-2,4--)ethylstyrene, poly-3,4-diethylstyrene, poly-2,4,5-trimethylstyrene, poly-2,4,6
-Trimethylstyrene, poly-2゜3.4-trimethylstyrene, poly-3,4,5-trimethylstyrene, poly-2,3,4,5-tetramethylstyrene, poly-2
, 4,5,6-tetramethylstyrene, poly-2,3,
5,6-tetramethylstyrene, poly-2,3,4,5
゜6-pentamethylstyrene, poly-2-methyl-4-
t-butylstyrene, poly-2-methyl-5-2-butylstyrene, poly-2-methyl-4-ethylstyrene
Z ly-2-methyl-5-ethylstyrene, poly-2-
Methyl-4-inzolopylstyrene, poly-2-methyl-5-isopropylstyrene, poly-2-methyl-4-
Examples include thiopentyl styrene, poly-4-cyclopropylstyrene, poly-4-cyclobutylstyrene, poly-4-cyclopentylstyrene, poly-4-cyclobutylstyrene, and at least one member selected from the group consisting of these. things are used. Among these, those having a glass transition point of 70° C. or higher are preferred because those with a low glass transition point tend to have poor heat resistance and resolution.

The molecular weight of the polymer used in the present invention is within the predetermined range described above. If this molecular weight is less than 2000, the glass transition point will decrease, the polymer will not form 151 bodies, and i
If it exceeds o x i o4t-, coating properties and resolution deteriorate. Further, the molecular weight dispersity of the polymer used is preferably monodisperse or as close to monodisperse as possible from the viewpoint of resolution. Therefore, as a method for producing a polymer belonging to group [A], a polymerization method such as living anion polymerization is preferable because it is easy to obtain a polymer with good monodispersity.

The bisazide compound used in the present invention may be any compound having at least two or more azide groups in one molecule, and includes, for example, those represented by the following structural formula.

Among these, preferably, the general formula: (wherein, X is a methylene group, oxy group, vinylene group, azo group, thio group, sulfonyl group, carzenyl group, E: -C
It is a compound represented by a group represented by H=CH-C-CH=CH-.

The blending ratio of this bisazide compound is usually 0.1 to 30 parts by weight per 100 parts by weight of the polymer having repeating units represented by the general formula CA).

If the blending ratio is less than 0.1 part by weight, the effect of the additive will be extremely reduced, and if it exceeds 30 parts by weight, the resolution will deteriorate. Preferably it is 0.1 to 20 parts by weight.

Note that the negative resist composition of the present invention may contain other vinyl polymers, organosilicon compounds, etc., if necessary.

In addition, substrates used in the present invention include, for example, a single silicon substrate doped with impurities, a semiconductor substrate such as one in which a polycrystalline silicon film is provided through a silicon oxide layer using this substrate as a base material, and a semiconductor substrate made of gallium arsenide or the like. Compound semiconductor substrate or aluminum oxide J-(At) on semiconductor substrate
, a substrate provided with a metal film such as molybdenum (Mo), a mask substrate such as a chromium film or a chromium oxide film laminated on a transparent glass plate, and the like.

〔Effect of the invention〕

Conventionally, bisazide compounds have been added to polyvinylcarnozole and polystyrene to increase sensitivity, but the sensitivity has not been sufficiently high for practical use due to the low sensitivity enhancement rate. According to the authors, by using as a resist the composition of the present invention of a specific polymer and a bisazide compound, which have been improved so that the reactivity with the bisazide compound can be particularly reduced, conventional polyvinylcarnozole and polystyrene can be used. It is possible to obtain a practical high-performance negative resist having much higher sensitivity than in the conventional case, and having good resolution, heat resistance, and dry etching resistance.

EXAMPLES Below, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

[Embodiments of the invention]

Examples 1 to 5 Polyvinyltoluene (PVT) as a polymer (molecular weight:
115,000, molecular weight dispersity: 1.1), polyinzolobylstyrene (PRST) (molecular weight: 91,000).

Molecular weight dispersity: 1.1), polyVt-zotylstyrene (PBSt) (molecular weight near, 20,000, molecular weight dispersity: 1
゜1), poly-2,5-dimethylstyrene (PDS) (
Molecular weight, 100,000, molecular weight dispersity: 1.1) and poly-
2,4,5-trimethylstyrene L/7 (PTSt) (molecules, IL: 80,000, molecular weight dispersity: 1.1) was used as a bisazi-P compound using the following formula: 2.0 per 100 of the polymer. A negative resist composition of the present invention was obtained by mixing in a ratio of (quantity ratio).

In order to evaluate the reaction of the obtained composition, the following test was conducted.

A xylene solution of the obtained composition was diluted to mM, and this solution was spin-coated onto a silicon substrate to form a resist thin film with a thickness of 5 μm. Next, the silicon substrate having the resist thin film was subjected to prepaging treatment at 100°C for 20 minutes, and then
A rectangular pattern (width: 20.0 μm, length: 400.!J) was formed using an electron beam with an accelerating voltage of 20 KV. The resist film after irradiation was developed using methyl isobutyl ketone and rinsed using isopropyl alcohol to form a resist pattern. Then 100
The remaining solvent was removed by bost paging at 10°C for 10 minutes.

In forming a turn using the electron beam described above, the irradiation amount (electron beam sensitivity) was measured at the 50-inch remaining film point of each sample shown in Table 1 by changing the irradiation amount, and the results are shown in Table 1. Shown below.

As a comparative polymer, Boristyrene/(PSt) (molecular weight = 9.6
Examples 1 to 5 using 10,000, molecular weight dispersity: 1.11
After preparing compositions in the same manner as above, the same treatments and evaluation tests as in Examples 1 to 5 were performed. The results are shown in Table 1.

As is clear from gi Table 1, compared to Comparative Example 1,
It can be seen that when the composition of the present invention is used, the sensitivity is increased 10 to 30 times.

Resolution evaluation test The compositions of the present invention obtained in Examples 3 and 4 were prepared.

Each of these compositions was spin-coated onto a silicon substrate treated with OAP C (manufactured by Tokyo Ohka Co., Ltd., adhesion promoter) to form a resist film with a thickness of 0.5 p. Then,
After applying Buripage treatment to the whole body at 100℃ for 30 minutes,
Electron beam with acceleration voltage 20KV (beam diameter: 0.1μ)
A desired groove including submicron turns was formed using the following method.

The composition used in Example 3 was developed using a mixed developer of methyl ethyl ketone (MEIO and isopropyl alcohol (IPA) (mixing volume ratio 50:50),
Rinsed with IPA.

The composition used in Example 4 was developed using a mixed developer of methyl isobutyl ketone (MIBK) and IPA (mixed volume ratio: 80:20), and rinsed with PA.

When the obtained resist pattern was evaluated, it was found that submicron/Ni~/ was formed with extremely high resolution.

The compositions of the present invention obtained in Examples 1 to 5 were prepared. fc to measure the dry etching rate ratio using these compositions.

This measurement was performed using LAM-480<manufactured by LAM>f.

Etching gas composition: 130scc of carbon tetrachloride
The test was carried out under the following conditions: 50 sec of helium, 210 mTorr of pressure, and 250 W power.

For comparison, polymethyl methacrylate (PMM
A) and Comparative Example 1 were used to carry out similar measurements.

The results are shown in Table 2.

Table 2 As is clear from Table 2, typical resist materials PM
It was found that the composition of the present invention had an order of magnitude higher dry etching resistance than MA.

Claims (1)

[Claims] 1. General formulas: ▲ Numerical formulas, chemical formulas, tables, etc. ▼ [A] (In the formula, R_1 to R_5 may be the same or different, each having 1 to 1 carbon atoms) Polymer 100 having a repeating unit represented by 10 alkyl groups or hydrogen atoms (except when R_1 to R_5 are all hydrogen atoms) and having a molecular weight of 2000 to 100 x 10^4 A negative resist composition comprising 0.1 to 30 parts by weight of a bisazide compound. 2. The polymer represented by the general formula [A] is poly-4-methylstyrene, poly-2-ethylstyrene, poly-4-t
-butylstyrene, poly-4-isopropylstyrene,
Poly-4-sec-butylstyrene, poly-4-neopentylstyrene, poly-2,5-dimethylstyrene, poly-3,4-dimethylstyrene, poly-2,4-dimethylstyrene, poly-3,5- dimethylstyrene, poly-
2,4,5-trimethylstyrene, poly-2,4,6-
Trimethylstyrene, poly-2,3,4-trimethylstyrene, poly-3,4,5-trimethylstyrene, poly-2,3,4,5-tetramethylstyrene, poly-2,
4,5,6-tetramethylstyrene, poly-2,3,5
, 6-tetramethylstyrene, poly-2,3,4,5,
The composition of claim 1 which is 6-pentamethylstyrene. 3. Bisazide compounds have general formulas: ▲Mathematical formulas, chemical formulas, tables, etc.▼[B] (In the formula, X is a methylene group, an oxy group, a vinylene group, an azo group, a thio group, a sulfonyl group, a carbonyl group, :-CH
Group represented by =CH-C-CH=CH-, formula: ▲numerical formula,
There are chemical formulas, tables, etc. The group shown by ▼ is a formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ represents the group shown. ) The composition according to claim 1, which is a compound represented by: