JPH01195441A - Resist material for precise processing - Google Patents

Abstract

PURPOSE:To obtain the title resist material having high sensitivity, high resolution, and high resistance to oxygen dry etching by adopting a specified polymer contg. a pyrimidine dimer and a siloxane bond in a molecular chain as a positive resist material. CONSTITUTION:A polymer expressed by formula I, contg. a pyrimidine dimer and a siloxane bond in a molecular chain is adopted as a positive resist material having high sensitivity for high energy beams. In formula I, each R<1> and R<2> is H atom., methyl group, halogen atom., or cyano group; each R<3> and R<4> is a methyl or a phenyl group; (l) is an integer 2-6; m is an integer 1-4; (n) is a positive integer. The mol.wt. of this positive resist material decreases due to cleavage at the pyrimidine dimer part by the irradiation with high energy beams such as far ultraviolet rays having <=260nm wavelength or electron rays, etc., and functions as a positive resist by being solubilized in a solvent. Thus, a resist material having high sensitivity, high resolution, and high resistance to oxygen dry etching, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resist material used for forming fine patterns in the manufacture of semiconductors.

[Prior Art] Conventionally, microfabrication in semiconductor manufacturing has been carried out using a naphthoquinone diazide/cresol novolac positive photoresist that is exposed to ultraviolet light, but the resolution is approaching its limit, and excimer laser It is desired to develop lithography technology using shorter wavelength light sources such as -.

On the other hand, as semiconductors have recently become more highly integrated and microfabrication on substrates has become more complex and precise, the height difference on the substrate has become larger. Therefore, the resist film thickness becomes thicker, making it difficult to obtain a high-resolution pattern.

As a process to solve this problem, a two-layer resist process has been proposed in place of the conventional method of using a single layer of resist. In this method, the substrate is first flattened by coating the substrate thickly with a conventional resist such as a naphthoquinone diazide/cresol novolak resist, and then a photosensitive resist with excellent oxygen dry etching resistance is coated on top. A thin layer is applied, exposed to light through a mask, and developed to form an upper resist pattern. Thereafter, by performing oxygen dry etching using this pattern as a mask, the lower resist layer is etched and a pattern is formed.

In particular, in excimer laser lithography, the depth of focus is shallow and the thicker the resist layer, the lower the resolution, so the two-layer resist process is an effective method.

[Problems to be Solved by the Invention] Conventional positive type deep tlV resist materials that can be used in excimer laser lithography are described in the Journal of Vacuum Science and Technology (J
, Vac, Sc1. Technol, ) B5. (1)
, P., 39B (19B?), but there is no material that can satisfy all the characteristics of sensitivity, resolution, and oxygen dry etching resistance, especially for the upper layer resist of a two-layer resist process. At present, there are almost no positive resist materials that can be used.

The present invention has been made in order to solve the above problems, and has high sensitivity, high resolution, and excellent oxygen dry etching resistance so that it can be used as an upper layer resist material in a two-layer resist process using excimer laser lithography. The purpose is to scale the resist material.

[Means for Solving the Problems] The present invention provides a general formula (1) having a pyrimidine dimer and a siloxane bond in the molecular chain; or a cyano group, and R' and R2 may be the same or different; R1 and R4 are methyl groups or phenyl groups; when there are multiple R3 and R4, they may be the same or different; , g is an integer of 2 to 6, - is an integer of 1 to 4, n is a positive integer, and the n Is and the two gs do not need to be the same). The present invention relates to a resist material for microfabrication, characterized in that it is used as a positive resist material that is highly sensitive to high-energy radiation.

[Function] The positive resist material according to the present invention is a polymer having a dimer of pyrimidine base and a siloxane bond in its main chain, and can be irradiated with high-energy rays such as deep ultraviolet rays of 28 Gno+ or less or electron beams. The pyrimidine base dimer part cleaves, the molecular weight decreases, and it functions as a positive resist by being solubilized in a solvent. Furthermore, since it has a siloxane bond in its molecule, the surface layer changes to 8102 during oxygen dry etching and becomes a barrier layer, so it has excellent oxygen dry etching resistance.

[Example] The resist material used in the present invention has the general formula (■): (
In the formula, R1 and R2 are a hydrogen atom, a methyl group, a halogen atom or a cyano group, R1 and R2 may be the same or different, R3 and R4 are a methyl group or a phenyl group, and R', R4 When there are multiple of each, they may be the same or different, g is an integer from 2 to 6,
(2) is an integer from 1 to 4, n is a positive integer, and the n so-called and 2i g's do not necessarily have to be the same.

If g in the general formula (1) is less than 2, the stability of the polymer will be poor, if it exceeds 6, the dry etching resistance of the resist will be poor, and if - is more than 4, the glass transition temperature of the polymer will be low. The resolution of the resist deteriorates. Further, n is a positive integer, and preferably 20 or more from the viewpoint of resist resolution.

Specific examples of the polymer represented by the general formula (I) include the following. Note that n in the formula is a positive integer, preferably an integer of 20 or more.

The resist material represented by the general formula (1) used in the present invention can be synthesized, for example, by the method (1) or (2). In addition, fl s 1i in the formula
%n is the same as above.

(CH2) TOH (CH2) p 0H IO(CH2) ,! (CHz)2F OH+ Method (1) can be used, for example, for 1-(2-hydroxyethyl)-5-methyluracil, 1-(2-hydroxyethyl)-5-cyanouracil, l-([i-hydroxyhexyl )-5-bromouracil, 1-(2-hydroxyethyl)-6-methyluracil, 1-(3-hydroxypropyl)-6-cyanouracil, etc., and 1,3-dichloro-1,3-dimethyl-1 , 3-diphenyldisiloxane, 1,5-dichlorohexamethyltrisiloxane,
(1) Mix 7-cyclooctamethyltetrasiloxane, dichlorodiphenylsilane, dichloromethylphenylsilane, etc., add pyridine and imidazole, and stir for 4 to 8 hours. Next, the solvent is distilled off under reduced pressure, and then washed with ethyl acetate and water, and the solvent is distilled off under reduced pressure.

Next, the obtained compound was dissolved in acetonitrile, dimethylformamide (DMP), dimethyl sulfoxide, etc., and placed in a Pyrex container using a high-pressure mercury lamp ("28").
UV rays are cut by 2~
After 4 hours of irradiation, the solvent is distilled off under reduced pressure.

In addition, method (2) uses 1-(2-hydroxyethyl)
-6-diatouracil, 1-(6-hydroxyhexyl)-5-bromouracil, 1-(2-hydroxyethyl)-5-methyluracil, etc. are dissolved in acetonitrile, dimethylformamide, dimethyl sulfoxide, etc.,
After irradiating with ultraviolet rays for 2 to 4 hours using a high-pressure mercury lamp (cuts light below 280 nm) in a Pyrex container, the solvent is distilled off to obtain a dimer. The dimer obtained next, 1,5-dichlorohexamethyltrisiloxane, 1,7-dichlorooctamethyltetrasiloxane, dichlorodiphenylsilane, 1,3-dichloro-
1,3-dimethyl-1,3-diphenyldisiloxane and the like are mixed, pyridine and imidazole are added, and the mixture is stirred for 4 to 8 hours. Next, the solvent is distilled off under reduced pressure, and then washed with ether, ethyl acetate, and water, and the solvent is distilled off under reduced pressure.

The polymer synthesized in this way is preferably added to a solvent such as dimethylformamide, dimethyl sulfoxide, or N-methylpyrrolidone in an amount of 2 to 30% (by weight, hereinafter the same).
After dissolving the solution to a concentration of
By heating for ~90 minutes to form a film, it can be used as a resist film. Note that the film thickness is usually 100
0 to 20,000 people, particularly 1,000 to 5,000 people when used as an upper resist material in a two-layer resist process in excimer laser lithography. As an exposure source for pattern formation, 2BOr
+m or less, preferably 180 to 255 nm deep ultraviolet rays,
Electron beams, X-rays, etc. can be used. On this occasion,
Exposure may be performed through a pattern mask if necessary.

As the developing solvent after exposure, alcoholic solvents such as methanol and isopropyl alcohol can be used.
Used alone or in a mixture.

The positive resist material of the present invention as described above has high sensitivity,
High resolution and excellent oxygen dry etching resistance.
It can also be suitably used as an upper layer resist material in a two-layer resist process in excimer laser lithography, where conventional resist materials have not yielded satisfactory results.

Next, the resist material of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 l-(2-hydroxyethyl)-6-diatouracil 1
．． 5 g was dissolved in 300 ml of acetonitrile, and irradiated with ultraviolet rays for 2.5 hours using a high-pressure mercury lamp (cutting light below 280 na+) in a Pyrex container. After the reaction, the solvent was removed by distillation to quantitatively obtain the dimer.

The dimer was confirmed by infrared spectroscopy and ln-NMH.

1.05 g (0, OQ 3 mol) of the obtained dimer and 1
,5-dichlorohexamethyltrisiloxane 0.03I
Mix with Ilol, stir, and add 2.5 m of pyridine.
1 and 0.41 g of imidazole were added, and stirring was continued for 5 hours. After the reaction, the solvent was distilled off under reduced pressure, and washed with ether, ethyl acetate, and water to obtain an average molecular weight of about 50,000 having a repeating unit represented by the formula:
obtained a polymer. The yield was 80%.

The obtained polymer was analyzed by infrared spectroscopy and '! Confirmed by 1-NMR. In addition, the infrared absorption spectrum of the polymer was measured. The results are shown in Figure 1.

The obtained polymer was made into a 10.0% dimethylformamide solution, spin coded on a silicon substrate at 200 rpm, and heated at 90° C. for 120 minutes to form a resist film. The film thickness at this time was 3000 people.

This film was coated with KrP excimer laser light (wavelength 248n).
Im s irradiation intensity 1011J107 pulses) 20 pulses were irradiated through a mask. After that, development was performed for 80 seconds with a developing solvent of methanol/ethanol (9/1).
A 60 second rinse was performed with n-butyl acetate. As a result, lines and spaces of 0.5AITI+ could be resolved. Further, as a result of examining the oxygen dry etching properties of the resist film using a parallel plate type reactive ion etching apparatus, the etching rate was 50 people/min, indicating good resistance.

Example 2 0.04 mol of l-(2-hydroxylethyl)-5-methyluracil and 0.02 mol of 1,3-dichloro-1,3-dimethyl-1,3-diphenyldisiloxane were mixed and stirred, Furthermore, 30 ml of pyridine and 0.04 mol of imidazole were added, and the mixture was stirred for 5 hours. Thereafter, the solvent was distilled off under reduced pressure, and the residue was washed with ethyl acetate and water to obtain crystals having a structure represented by the formula: The yield was 97%.

The obtained compound was identified by infrared spectroscopy and 'H-NMR.

1.5 g of the obtained compound was added to 300 ml of acetonitrile.
in a high-pressure mercury lamp (2
(cuts light below 80na+) to reduce ultraviolet rays by 2.5
It was irradiated at the time. Next, by distilling off the solvent under reduced pressure, an average molecular weight eoooo having a repeating unit represented by the formula:
The polymer was quantitatively obtained.

The structure of the obtained polymer was investigated and confirmed in the same manner as in Example 1.

The resulting polymer was made into a 1000% dimethylformamide solution, spin coded on a silicon substrate at 200 rpm, and heated at 90° C. for 120 minutes to form a resist film. The resist film thickness at this time was 3000.

This film was developed in the same manner as in Example 1 by irradiating 30 pulses of KrP excimer laser light.

As a result, we were able to resolve lines and spaces of 0.4 degrees. In addition, the oxygen dry etching rate of the resist film is 45
person/minute.

Example 3 From l-(6-hydroxyhexyl)-5-bromouracil and 1,7-dichlorooctadimethyltetrasiloxane, an average molecular weight of 80,000 having a repeating unit represented by the formula:
obtained a polymer.

The structure of the obtained polymer was investigated and confirmed in the same manner as in Example 1.

Using the obtained polymer, a 20.0% dimethylformamide solution was prepared, and a resist film was formed in the same manner as in Example 1. The thickness of the resist film at this time was 1.0-.

This film was exposed to light through a mask at 300 mJ/cj (254 nm) using a low-pressure mercury lamp as a light source.

Thereafter, development and rinsing were performed in the same manner as in Example 1.

As a result, 0.8 lines and spaces could be resolved. The oxygen dry etching rate was 80 people/min.

Example 4 ■-(2-Hydroxyethyl)-6-diatouracil and dichlorodiphenylsilane were used as monomers in the same manner as in Example 1 to obtain a compound having an average molecular weight of 40,000 and having a repeating unit represented by the formula:
obtained a polymer.

The structure of the obtained polymer was investigated and confirmed in the same manner as in Example 1.

A resist film was formed in the same manner as in Example 1 using the obtained polymer. The thickness of the resist film at this time was 3000
It was a person.

Next, the electron beam (acceleration voltage 25
kV, spot diameter 0. II, current 5 x 10-10
A) was irradiated. Thereafter, development was performed in the same manner as in Example 1 to obtain a resist pattern. As a result, 4μC/
I was able to change the sensitivity of c- and resolve lines and spaces of 0.3 am.

[Effects of the Invention] As described above, the resist material of the present invention is a resist material with high sensitivity, high resolution, and excellent oxygen dry etching resistance that can be applied as an upper layer resist in a two-layer resist process in excimer laser lithography. , E.B.
It can also be used as a commercial resist, and can realize microfabrication with high precision on the submicron order.

[Brief explanation of the drawing]

FIG. 1 is a chart showing the infrared absorption spectrum of the polymer obtained in Example 1.

Claims (1)

[Claims] (1) General formula (I) with a pyrimidine dimer and siloxane bond in the molecular chain: ▲Contains mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R^1 and R^2 are hydrogen atoms, A methyl group, a halogen atom or a cyano group, R^1 and R^2 may be the same or different, R^3 and R^4 are a methyl group or a phenyl group, R^3 and R^ When there are multiple 4s, they may be the same or different.
l is an integer of 2 to 6, m is an integer of 1 to 4, and n is a positive integer; n m's and 2n l's are not necessarily the same. A resist material for microfabrication that is characterized by its use as a positive resist material that is highly sensitive to energy rays.