JPH0635194A - Negative photoresist composition - Google Patents

Abstract

PURPOSE:To obtain a compsn. having sensitivity in a near-UV region and resolution of specified value or smaller and improved sensitivity and dry etching resistance by incorporating a specified sensitizer. CONSTITUTION:This compsn. contains an alkali-soluble resin, photooxygen generating agent, crosslinking agent which crosslinks the alkali soluble resin in acid conditions, and sensitizer expressed by formula I. sensitizer gives sensitivity in the near-UV region (i-line at 365nm wavelength) and resolution of <=0.5mum into the photooxygen generating agent. In formula I, m and n are 1 or 2, R1 and R2 are expressed by formula II or III, wherein R3-R8 are H or lower alkyl groups, R1-R8 may be same or different. In the pattern forming process, this negative photoresist compsn. is dissolved in a solvent, filtered if necessary, and applied on a substrate such as silicon wafer with a spin coater, dried at 70-160 deg.C, preferably 80-140 deg.C, exposed through a specified mask, and further heated at 80-160 deg.C, preferably 90-150 deg.C to be developed.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an alkali-soluble resin, a photo-acid generator, a cross-linking agent that cross-links the alkali-soluble resin under acidic conditions, and a sensitizer that imparts photosensitivity to the near-ultraviolet region. The present invention relates to a negative photoresist composition contained therein, and particularly to a negative photoresist composition suitable for producing a semiconductor circuit such as an IC.

[0002]

2. Description of the Related Art As semiconductor circuits become more highly integrated and required resolution becomes 0.5 .mu.m or less, a g-line (436 nm) to an i-line (36 nm) which can obtain higher resolution in a light source.
(5 nm) Further, the wavelength has been shortened to deep ultraviolet rays (300 nm or less), and in particular, a reduction projection exposure apparatus for i-line has been put into practical use, and a resist having high sensitivity and high resolution adapted to this i-ray region. Is strongly desired.

As a negative type photoresist used for forming a semiconductor circuit, there is a negative type resist using a cyclized rubber and bisazide, but since this system uses an organic solvent for development, swelling occurs at the time of development and its resolution. Is 2-3 μm
Is the limit. Therefore, it is not suitable for manufacturing a highly integrated semiconductor circuit. Further, the organic solvent used for the development is not preferable in terms of environment, hygiene and flammability, and a water-soluble development system is desired. Further, in order to enhance the dry etching resistance required for fine processing after development, it is necessary to use a resin having an aromatic ring, but a cyclized rubber system cannot obtain sufficient resistance. JP-A-63-191
No. 142 has an example of a composition using an alkali-soluble resin and a bisazide compound. Since it uses polyvinylphenol or a formalin condensate of m-cresol and p-cresol as an alkali-soluble resin, it is alkali developable and swells. It also has excellent resolution and high dry etching resistance, but has the drawback that it is difficult to control because it is easily affected by oxygen. In recent years, many negative photoresists containing a photo-acid generator capable of obtaining high sensitivity have been studied, and resists having high sensitivity and excellent resolution have been developed. However, many photo-acid generators used therein have strong absorption in the deep ultraviolet region, but hardly absorb in the i-line region, making pattern formation difficult.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an alkali having photosensitivity in the i-line (365 nm) region and having a resolution of 0.5 μm or less, high sensitivity, heat resistance and dry etching resistance. It is an object of the present invention to provide a developable negative photoresist composition.

[0005]

Means for Solving the Problems As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, it was found that a composition containing specific components has high sensitivity and high resolution and can be developed with an alkali. The present invention has been found and has led to the present invention. That is, the present invention provides an alkali-soluble resin, a photo-acid generator, a cross-linking agent that cross-links the alkali-soluble resin under acidic conditions, and an additive represented by the formula (1) that imparts photosensitivity in the near ultraviolet region to the photo-acid generator. A negative photoresist composition containing a sensitizer.

[0006]

[Chemical 3]

[0007]

[Chemical 4]

In the formula (1), m and n are 1 or 2,
R _1, R _2, the equation (2) or formula (3), R _3,
R ₄ is H or a lower alkyl group, R ₅ , R ₆ ,
R ₇ and R ₈ each represent H or a lower alkyl group,
R _{1 to} R ₈ may be the same or different. I will provide a.

The present invention will be described in detail below. Examples of the alkali-soluble resin used in the present invention include polyhydroxystyrene and its derivatives, hydroxystyrene copolymers such as hydroxystyrene-styrene copolymer, hydroxystyrene- (meth) acrylic acid ester copolymer, and hydroxystyrene-. Examples thereof include (meth) acrylic acid copolymers. Still another alkali-soluble resin is an alkali-soluble novolac resin. As the alkali-soluble novolac resin, a condensate of phenol, cresols, xylenols, pt-butylphenol, naphthol, bisphenol A, bisphenol F, bisphenol S, and other aldehydes with formaldehyde, paraformaldehyde, chloroaldehyde, and other aldehydes. However, the present invention is not limited to these. These resins can be used alone or in combination of two or more.

Further, in order to improve the contrast of the image by increasing the solubility difference between the irradiated part and the unirradiated part in the alkali developing solution, and to improve the adhesiveness to the silicon substrate or the chromium substrate, the above-mentioned has been mentioned. The weight average molecular weight (Mw) of the polymer is preferably 1,000 to 20,000, and more preferably 2,000 to 15,000.

Examples of the photoacid generator include halogenated isocyanurate and halogenated methylphenyl sulfone. Specific examples thereof include 1,3,5-tris (2,3-dibromopropyl) -1,3,5-triazine-2,4,6- (1H, 3H, 5H) trione and tribromomethylphenyl. Sulfone, trichloromethylphenyl sulfone, tribromomethyltolyl sulfone, 2,
2-bis (4-methoxyphenyl) -1,1,1-trichloroethane, 1,1-bis (p-chlorophenyl)-
2,2,2-trichloroethane and the like can be mentioned, but the present invention is not limited thereto.

Examples of the cross-linking agent include urea resin, melamine resin, benzoguanamine resin and glycoluril resin. Specific examples thereof include Cymel 300, 301, 303, and 3 manufactured by Mitsui Cyanamid Co., Ltd.
50, 370, 380, 1116, 1130 and Nikarac MW-30, MW-22 manufactured by Sanwa Chemical Co., Ltd.
Melamine resins such as A, cymel 1123, 1125 and benzoguanamine resins such as Nicarac BX-4000,
Examples include glycoluril resins such as Cymel 1170, 1171, 1172 and urea resins such as UFR65, 300, but the present invention is not limited thereto.

As the sensitizer, the compound represented by the formula (1) is used, and these can be synthesized by the method described in JP-B-55-41261. These compounds may be used alone or in combination of two or more. Specific examples include 3,3′-bis-α, α-dimethylbenzylphenothiazine and Antage STDP-N (manufactured by Kawaguchi Chemical Industry Co., Ltd.). This Antage STDP-
N is m or n is 1 or 2 in the formula (1),
R ₁ and R ₂ are the formula (2) or the formula (3), and R ₃ and R
_{One of 4} is H, the other is a methyl group, and R ₅ , R ₆ , R ₇ , and R ₈ are all H, which is a mixture of 6 components. The photoresist composition of the present invention has a photoacid generator of 0.01 to 50, preferably 0.1 to 100 parts by weight of an alkali-soluble resin.
To 30 parts by weight, more preferably 1 to 100, more preferably 5 to 5
0 part, sensitizer 0.01 to 50, preferably 0.1 to 3
Obtained by mixing 0 parts.

The negative photoresist composition of the present invention is preferably used by dissolving it in a solvent, and the solvent is methyl ethyl ketone, cyclohexanone, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, 1-methoxy. -2
-Propyl-acetate, methyl lactate, ethyl lactate, propyl lactate and the like can be used. In particular, the lactates and 1-methoxy-2-propyl-acetate, which have a strong dissolving power and low toxicity for the composition of the present invention, are useful. These solvents may be used alone or in admixture of two or more.

If necessary, the negative photoresist composition of the present invention may contain a dye, an adhesion aid, a surfactant, a storage stabilizer, an antifoaming agent and the like.

Pattern formation using the composition of the present invention is carried out, for example, as follows. The negative photoresist composition of the present invention is dissolved in the above solvent so as to have a solid content of 5 to 100% by weight, filtered if necessary, and then coated on a substrate such as a silicon wafer by a spin coater or the like 70 to 1
A good resist pattern can be obtained by drying at 60 ° C., preferably 80 to 140 ° C., exposing through a predetermined mask, heating at 80 to 160 ° C., preferably 90 to 150 ° C., and developing. The heat treatment after the exposure is a treatment for sensitizing the sensitivity of the negative photoresist composition and is a preferable treatment for achieving the object of the present invention. If the treatment temperature at this time is less than 80 ° C., curing will not be performed. Sufficient film reduction and difficulty in obtaining practical sensitivity.
If the temperature exceeds 60 ° C., the transfer patterns are joined together and it becomes difficult to obtain a good pattern. The developer used in the developing treatment is an aqueous solution of an inorganic alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or an aqueous solution of an organic alkali such as tetramethylammonium hydroxide, trimethanolamine or triethanolamine. Can be given.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Synthesis Example (Synthesis of 3,3′-bis-α, α-dimethylbenzylphenothiazine) 3,3′-bis-α, α-dimethylbenzylamine 4
0.5 g, sulfur 6.4 g and iodine as catalyst 0.0
Charge 4 g into a three-necked flask, and use an oil bath at 200 ° C.
The reaction is continued until the hydrogen sulfide is no longer generated.
After cooling, an oily reaction product is obtained. This was dissolved in acetone, residual sulfur was removed by filtration, methanol was added to this filtrate for crystallization, and filtration was performed to obtain a purified product. This purified product was analyzed by NMR and mass spectrometry (molecular weight 43
From 5), it was confirmed that this purified product was 3,3′-bis-α, α-dimethylbenzylphenothiazine.

Example 1 Polyhydroxystyrene having a weight average molecular weight of 5,200 as an alkali-soluble resin (trade name: Linker S-2P
10 g of Maruzen Petrochemical Co., Ltd., 0.5 g of tribromomethylphenyl sulfone, 2.0 g of Cymel 1123 made by Mitsui Cyanamid Co., Ltd., and 0.5 g of Antage STDP-N (made by Kawaguchi Chemical Co., Ltd.) ethyl lactate. It was dissolved in 38 g and filtered using a 0.2 μm Teflon membrane filter to prepare a photoresist composition. This photoresist composition was applied on a silicon wafer with a spinner and dried on a hot plate set at 110 ° C. for 90 seconds to obtain a resist film having a film thickness of 1.1 μm. A UV-D35 / V-42 filter (manufactured by Toshiba Glass Co., Ltd.) was passed through this film with a 500 W xenon-mercury lamp, and exposure (exposure amount 90 mJ / cm ² ) was performed through a mask on which a fine pattern was drawn. . After exposure, it was baked on a hot plate set at 130 ° C. for 90 seconds and developed with 2.38% TMAH (tetramethylammonium hydroxide) at 23 ° C. for 60 seconds. The residual film rate of the resist pattern thus obtained was 92%. As a result of observation with a scanning electron microscope, the cross-sectional shape was rectangular and the minimum line width on the mask used was 0.5 μm.
Was confirmed to be resolved.

Examples 2 to 16 Examples except that the type of alkali-soluble resin, the type of photo-acid generator, the type of cross-linking agent, the type of sensitizer, and the respective compounding amounts were changed as shown in Table 1. Perform the same operation as 1.
The characteristics of each resist composition were evaluated. The results are also shown in Table 1. In all of Examples 1 to 12, the residual film rate of the resist pattern was 90% or more, and the minimum line width of 0.5 μm on the used mask was resolved, and it was confirmed that the cross-sectional shape was rectangular. It was also confirmed that the sensitivity at this time was 200 mJ / cm ² or less, which was sufficiently high in practical use.

Comparative Examples 1 to 8 Samples without addition of sensitizer as shown in Table 2 were treated as in Example 1. The results are also shown in Table 2.
However, the exposure amount was 400 mJ / cm ² .

Table 1 Examples Resin Photo-acid generator Crosslinking agent Sensitizer Sensitivity Resolution Remaining film rate (%) 2 PVP DBT 1123 STDP 90 0.5 95 10g 0.5g 2g 0.5g 3 PVP BMPTC 1123 STDP 80 0.5 94 10g 0.5g 2g 0.5g 4 PVP TBMPS 1123 STDP 70 0.5 95 10g 0.5g 2g 0.5g 5 PVP TBMPS 1123 STDP 130 0.5 95 10g 0.5g 2g 0.3g 6 PVP TBMPS 303 DMBPT 70 0.5 90 10g 0.5g 2g 0.5g 7 PVP TMPPS 1170 DMBPT 70 0.5 92 10g 0.5g 2g 0.5g 8 PVP TMPPS 65 DMBPT 100 0.5 90 90g 0.5g 2g 0.5g 9 CST TBM PS 1123 STDP 120 0.5 90 10g 0.5g 2g 0.5g 10 CST BMPTC 1123 DMBPT 120 0.5 90 90g 0.5g 2g 0.5g 11 pmC TBMPS 1123 STDP 60 0.5 96 96g 0.5g 2g 0 0.5 g 12 tBB BMPTC 1170 STDP 70 0.5 94 10 g 0.5 g 2 g 0.5 g

[0023]

Alkali-soluble resin PVP: p-hydroxystyrene (Maruzen Petrochemical Co., Ltd.)
Product name: Marcalinker S-2P) CST: p-hydroxystyrene-styrene copolymer (Maruzen Petrochemical Co., Ltd. product name: Marcalinker CS
T-70) CMM: p-hydroxystyrene-methylmethacrylic acid copolymer (manufactured by Maruzen Petrochemical Co., Ltd., trade name: Marcalinker CMM) pmC: p-cresol and a condensate of m-cresol and formaldehyde (p- Composition ratio of cresol and m-cresol 3: 7, weight average molecular weight by GPC 520
0) tBB: pt-butylphenol and a condensate of bisphenol A and formaldehyde (composition ratio of pt-butylphenol and bisphenol A 3: 7, weight average molecular weight by GPC 5300)

Photoacid generator DBT: 1,3,5-tris (2,3-dibromopropyl) -1,3,5-triazine-2,4,6- (1H,
3H, 5H) trione TBMPS: tribromomethylphenyl sulfone BMPTC: 2,2-bis (4-methoxyphenyl)-
1,1,1-trichloroethane

Crosslinking agent 303: Cymel 303 (manufactured by Mitsui Ciana Mid Co., Ltd.) 1123: Cymel 1123 (manufactured by Mitsui Ciana Mid Co., Ltd.) 1170: Cymel 1170 (manufactured by Mitsui Ciana Mid Co., Ltd.) 65: UFR65 (manufactured by Mitsui Ciana Mid Co., Ltd.)

Sensitizer STDP: Antage STDP-N (manufactured by Kawaguchi Chemical Industry Co., Ltd.) DMBPT: 3,3'-bis-α, α-dimethylbenzylphenothiazine

The sensitivity was expressed as an exposure dose (unit: mJ / cm ² ) for reproducing a mask pattern of 1.0 μm. The residual film rate represents the percentage of the film thickness ratio before and after development in the exposed area.
The resolution is the minimum resolution pattern size (unit: μm) when exposed with an exposure amount that reproduces a mask pattern of 1.0 μm.
Expressed as

[0029]

The negative photoresist composition of the present invention has extremely high sensitivity to radiation such as near-ultraviolet rays and can be developed with an alkali, and the resist pattern transferred onto the substrate is not significantly reduced in film thickness and has extremely high resolution. Since it is excellent, it is extremely useful for manufacturing semiconductor integrated circuits.

Claims (1)

[Claims] 1. An alkali-soluble resin, a photo-acid generator, a cross-linking agent that cross-links the alkali-soluble resin under acidic conditions, and an increase represented by the formula (1) that imparts photosensitivity to the near-UV region. Negative photoresist composition containing a sensitizer [Chemical 2] In the formula (1), m and n are 1 or 2, R ₁ , R ₂ ,
Represents formula (2) or formula (3), R ₃ , R ₄ represents H or a lower alkyl group, R ₅ , R ₆ , R ₇ and R ₈ represent H or a lower alkyl group, and R ₁ to R ₈ may be the same or different.