JPH0527440A - Resist composition and resist pattern forming method - Google Patents

Abstract

PURPOSE:To improve the resolution of a positive resist compsn. CONSTITUTION:This resist compsn. contains base resin having phenolic hydroxyl groups in the molecule, a photosensitive agent and a dioxy-pyrimidine deriv. represented by the formula as essential components. In the formula, each of R1 and R2 is H or 1-20C alkyl and each of R3 and R4 is H, 1-3C alkyl, carboxyl, cyano or hydroxyl.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist having excellent resolution and high sensitivity and a pattern forming method thereof.

Due to the need to process a large amount of information at high speed, information processing apparatuses are being made smaller and larger in capacity, and the semiconductor devices that make up the main body of this apparatus are also becoming larger in capacity and LS.
I and VLSI have been put to practical use, but further integration has led to ULSI
Is being developed.

Here, since the integration is mainly performed by miniaturizing the unit element, the electrode pattern and the conductor line are becoming finer and finer, and the minimum line width is a submicron (Sub-micron).
-micron) has been reached.

For example, the latest memory, a 64 Mbit D-
The minimum line width of RAM is 0.3 μm. Here,
All pattern formation, including such fine patterns, is performed using photolithography (photolithography or electron beam lithography). For that purpose, the development of resists with better resolution than before is necessary.

[0005]

2. Description of the Related Art The use of a resist material having a high pattern accuracy is indispensable for miniaturization of semiconductor integrated circuits. As a typical conventional positive resist, a phenol novolac resin is used as a photosensitizer and a naphthoquinonediazide derivative is used as a photosensitizer. The added one is used.

The characteristic of this resist is that it can be developed with an alkali, the amount of swelling is small, and therefore the resolution is good. For example, OFPR series (Tokyo Ohka), PFR series (Nippon Synthetic Rubber), etc. Is used for.

However, it is difficult to meet the purpose of forming a submicron pattern with high accuracy as described above in response to high integration of a semiconductor integrated circuit, and it is possible to obtain high sensitivity and high resolution. It is required to develop a resist material provided with the resist material.

[0008]

The degree of integration is extremely high,
Semiconductor integrated circuits containing many submicron patterns
In order to mass-produce with high yield, it is necessary to put into practical use a resist with higher sensitivity and higher resolution than before, and this development is an issue.

[0009]

The above problems can be solved by forming a resist composition containing a base resin having a phenolic hydroxyl group in the molecule, a photosensitizer and a dioxypyrimidine derivative as main components. .

[0010]

The present invention uses a dioxypyrimidine derivative as a base resin dissolution inhibitor and a photofunctional acid generator or base generator as a photosensitizer.

That is, the dioxypyrimidine derivative represented by the general formula (1) is a weak base and at the same time has a carbonyl group (> C = O) which is strongly bonded to the phenolic hydroxyl group. Pyrimidine strongly binds to a resin having a phenolic hydroxyl group.

Therefore, the base resin having a phenolic hydroxyl group such as phenol novolac resin is insoluble in an alkaline aqueous solution such as tetramethylammonium hydroxide.

However, when the photo-functional acid generator or base generator added as a photosensitizer is irradiated with ionizing radiation such as ultraviolet rays or electron beams to generate acid or base,
The equilibrium of acid / base bond and hydrogen bond between the base resin and dioxypyrimidine is moved, and as a result, the bond between dioxypyrimidine and the resin is broken, and the mutual association of dioxypyrimidine is promoted.

Therefore, in the exposed area where such a reaction proceeds, the solubility of the base resin in the alkaline aqueous solution is restored, and development becomes possible. Further, the acid or base generated by irradiation with ionizing radiation is involved in the transfer of chemical equilibrium, and the presence of one acid or base can break many bonds.

That is, chemical amplification is carried out, and thereby high sensitivity is realized. Further, since the diffusion distance of the acid generated from the acid generator or the base generated from the base generator upon irradiation with light is as short as 5 nm or less, high resolution can be realized.

[0016]

【Example】

Example 1 10 g of polyvinylphenol (abbreviation PVP) having a molecular weight of about 12000 was dissolved in 100 ml of dimethylformamide, and 6 mol% of diphenyliodonium hexafluoroborate (photoacid generator) per PVP residue was used as a photosensitizer. As a dioxypyrimidine derivative (dissolution inhibitor)
28 mol% thymine was added and dissolved by stirring to form a uniform solution, which was passed through a filter having a pore size of 0.1 μm to prepare a resist solution.

This resist solution was spin-coated on a Si substrate to a film thickness of 0.1 μm and then baked at 90 ° C. for 30 minutes. The resist film thus obtained is irradiated with ultraviolet light having a wavelength of 365 nm through a mask, and then,
After baking at 120 ° C. for 2 minutes, development was performed with a 0.25 N tetramethylammonium aqueous solution.

As a result, a line and space pattern of 0.4 μm could be resolved, and the exposure dose required for this was about 20 mJ / cm ² . Example 2: 10 g of phenol novolac with a molecular weight of about 4000
Was dissolved in 100 ml of dimethylformamide, and 6 mol% of tetrabromobisphenol A (acid generator) per residue of phenol novolac was used as a photosensitizer and 28 mol% of N, N as a dioxypyrimidine derivative (dissolution inhibitor). -Dimethylthymine was added and dissolved by stirring to form a uniform solution, which was passed through a filter with a pore size of 0.1 μm to prepare a resist solution.

This resist solution was spin-coated on a Si substrate to a film thickness of 0.1 μm and then baked at 90 ° C. for 30 minutes. The resist film thus obtained was irradiated with an electron beam at an accelerating voltage of 20 KV, then baked at 120 ° C. for 2 minutes, and then developed with a 0.25 N tetramethylammonium aqueous solution.

As a result, a line and space pattern of 0.3 μm could be resolved, and the exposure dose required for this was about 10 μC / cm ² .

[0021]

INDUSTRIAL APPLICABILITY According to the present invention, a positive resist having excellent resolution with respect to ionizing radiation such as ultraviolet rays and electron beams and having high sensitivity can be obtained. By using this resist composition, a submicron pattern can be formed. It can be formed with high yield.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Manami Fukuda             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited

Claims (6)

[Claims] 1. A resist composition comprising a base resin having a phenolic hydroxyl group in the molecule, a photosensitizer, and a dioxypyrimidine derivative as main components. 2. The resist composition according to claim 1, wherein the base resin having a phenolic hydroxyl group in the molecule is an alkali developable resin such as polyvinyl phenol or phenol novolac resin. 3. The resist composition according to claim 1, wherein the photosensitizer is a photofunctional acid generator that reacts with ionizing radiation to generate an acid. 4. The resist composition according to claim 1, wherein the photosensitizer is a photofunctional base generator that reacts with ionizing radiation to generate a base. 5. The resist composition according to claim 1, wherein the dioxypyrimidine derivative is a compound represented by the following general formula (1). [Chemical 1] Here, R ₁ and R ₂ are independently hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ₃ and R ₄ are independently hydrogen or an alkyl group having 1 to 3 carbon atoms, a carboxyl group, and a cyano group. Group or hydroxyl group, 6. A method for forming a resist pattern, which comprises coating a resist comprising the resist composition according to claim 1 on a substrate to be treated, and performing selective exposure and development.