JPH02262152A - Photoresist material - Google Patents

Abstract

PURPOSE:To obtain a photoresist material appliable in the wide wave-length region and high in resolution after development by using a copolymer consisting of a monomer having a main chain composed of specified repeating units and a vinyl monomer having an aromatic ring or aromatic hetero ring in a molecular structure having a specified average molecular weight. CONSTITUTION:The photoresist material is composed of the copolymer of the monomer having the main chain substantially composed of repeating units each represented by formula I and the vinyl monomer having an aromatic ring or aromatic hetero ring in the molecular structure, and the copolymer has an average molecular weight of 5X10<5> - 5X10<7>. In formula I, each of R<1> and R<3> is H, methyl, or like; R<2> is 1 - 6 C alkyl; R<4> is 1 - 8 C fluoroakyl, and l/m is 0.6 - 1.5, thus permitting the obtained photoresist to form a resist micropattern high in resolution by irradiation with lights in the wavelength region from ArF excimer laser beams to X-rays.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention uses methyl methacrylate as one component, and a photosensitizer suitable for excitation with short wavelength light or an X-ray light source is added to the methyl methacrylate chain skeleton. The present invention relates to a photoresist material which has hydrofluoric acid resistance and which absorbs short wavelength light and becomes low in molecular weight.

(Prior Art) Polymethyl methacrylate (PMMA), which is well known as a polymer resist material, is used as a photoresist material.

However, from the viewpoint of sensitivity of resist materials, contrast during development, heat resistance, etc., aromatic groups are added to side chains or halides are bonded to aromatic carbon, and after removal by molecularly cutting the halogen atoms by light irradiation, other methods are used. Stabilization methods have been used such as addition of alkyl groups and cross-linking reactions between molecules.

Halogens, such as chlorine, released by molecular scission can damage materials and reaction vessels. Further, although positive resists have good resolution and contrast, it is difficult to control the resist after molecular cutting after light irradiation, and there are drawbacks in that negative resists are also generated by light irradiation.

(Problems to be Solved by the Invention) Therefore, the present invention is directed to the short wavelength region, particularly from 10 nm to 200 nm.
The purpose of the present invention is to provide a polymer resist material that can be applied in a wide wavelength range of nm, has high resolution after development, and has excellent contrast.

(Means for solving the problem) The above purpose is to achieve the above purpose in which the main chain is substantially the following repeating unit (however,
In the formula, R11R3 is a hydrogen group, a methyl group, or an ethyl group,
R2 is an alkyl group having 1 to 6 carbon atoms, and R4 is an alkyl group having 1 to 6 carbon atoms, and R4 is an alkyl group having 1 to 6 carbon atoms, and R4 is an alkyl group having 1 to 6 carbon atoms, and R4 is an alkyl group having 1 to 6 carbon atoms;
8, and Q/m=0.6 to 1.
It is 5. ) and a vinyl monomer having an aromatic ring or a heteroaromatic ring in its molecular skeleton, and has an average molecular weight of 5xlO5 to 5x107.

In addition, the main chain is substantially the following repeating unit (however, in the formula R
1, R3, and R5 are hydrogen, methyl, or ethyl groups, R2 is an alkyl group having 1 to 6 carbon atoms, and R4 is a fluorinated group having 1 to 8 carbon atoms in which at least one hydrogen atom has been replaced with a fluorine atom. is an alkyl group, and R8 represents any one of the following. ) and a copolymer with a vinyl monomer having an aromatic ring or a heteroaromatic ring in the molecular skeleton, and has an average molecular weight of 5X10
This is accomplished with a photoresist material that is '~5XlO'.

In addition, the main chain is substantially the following repeating unit (however, in the formula R
1, R3, R5 are hydrogen group, methyl group, or ethyl group,
R2 is an alkyl group having 1 to 6 carbon atoms, and R' is an alkyl group having 1 to 6 carbon atoms, and R' is an alkyl group having 1 to 6 carbon atoms, and R' is an alkyl group having 1 to 6 carbon atoms;
8 is a fluorinated alkyl group, and Ro represents one. ) and a copolymer with a vinyl monomer having an aromatic ring or a heteroaromatic ring in the molecular skeleton, and has an average molecular weight of 5X10' to 5X10.
'Achieved by a photoresist material.

(Function) The resist material of the present invention needs to have good transmittance and good irradiation energy absorption for light with a short wavelength of 50 to 300 nm (laser light, X-rays, etc.). Such a resist material has an average molecular weight of 5×105 to 5×
107, a polymethacrylic acid ester copolymer.

Examples of the polymethacrylic acid ester include methacrylic acid having an ester group consisting of an alkyl group having 1 to 4 carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. Among the esters, methyl methacrylate is particularly preferred.

Further, among the above-mentioned resist materials, a preferable high-molecular polymethacrylic acid ester polymer is a copolymer with another vinyl monomer having a color-forming group whose absorption peak is in the ultraviolet wavelength region. In such a copolymer, the photosensitizing effect is achieved by the other monomer incorporated into the copolymer, so that the sensitized light absorption characteristics may be affected by external factors such as temperature. It is extremely stable and exhibits high edging efficiency.

The methacrylic acid esters constituting this copolymer include esters having an alkyl group of 1 to 4 carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. Among them, methyl methacrylate is particularly preferred.

On the other hand, compounds with color-forming groups that exhibit absorption peaks in the wavelength range of 10 to 200 nm include biphenyl groups having aromatic or heteroaromatic rings, naphthyl groups, anthrylmethyl groups, fluorenyl groups, pyridine groups, N - Examples include those having a carbazole group, anthracene group, and ferrocene group.

The method for producing a high molecular weight polymethacrylic acid ester copolymer involved in pattern formation of the present invention involves irradiating plasma into a gas phase containing monomer vapor, and generating polymerization-initiating active species such as benzoyl peroxide, dichloromethane, etc. It can be easily prepared with good yield by a plasma initiated polymerization method using a radical polymerization initiator for chain growth polymerization of monomers such as milperoxy, azobisisobutyronitrile, etc.

The short wavelength light used is ArF excimer laser (
Wavelength: 193 nm), X-rays, especially soft X-rays around 10 nm, can be used.

(Example) Hereinafter, the present invention will be specifically explained based on Examples.

Example 1 Pyrex glass polymer tube with inner diameter 15+nm (capacity 4
2ml) of methyl methacrylate (MMA) 5.34
ml (5,00X 10” mol), hexafluoroisopropyl methacrylate (HPIPMA) 11.86
g (5,Ox 102mol) and benzoyl peroxide (BPO) 0.014g (4,13X 103mol)
1/12), the polymerization tube was connected to a vacuum line, and frozen with liquid nitrogen. This system was degassed at 10-3 Torr or less to sufficiently remove oxygen from the system and melt it again. After repeating this operation three times, the cock was closed and when a portion of the monomer in the polymerization tube began to dissolve, plasma was generated in the gas phase. 5 by a 13.56MHz high frequency generator
Plasma treatment was performed at 0 N for 60 seconds.

The polymerization tube was sealed and allowed to stand at 25°C for 5 days of polymerization. The obtained polymerization reaction product was dissolved in 40 m2 of benzene, reprecipitated twice with a methanol solution (800 m12), and vacuum-dried at 80°C to obtain the desired copolymer (white polymer) (yield: 3.168 wt%).

The viscosity average molecular weight at 25°C is M v = 1.02x
It was io7. In addition, the Mark Howink equation [η)=
KM'te coefficient=7.5XlO'', a=O,'IO
I asked for a replacement.

A 1 wt% methyl isobutyl ketone (formerly BK) solution of the obtained polymer was coated with a spin coater (IH manufactured by Mikaza Co., Ltd.).
-D2 type) on a silicon wafer with a film thickness of 0.1
A polymer thin film of μm was formed. Thereafter, a prebaking process (110'C, 30 minutes) was performed to obtain a polymer thin film (resist substrate) on the silicon substrate. Note that the molar ratio of methyl methacrylate and hexafluoroisopropyl methacrylate at this time was 1:1.

This resist substrate was irradiated with an excimer laser as follows.

Manufactured by Tachist Laser System Incorporated 5
An ArP (193 nm) laser beam is generated using the OIXR type, and passed through a slit (width 1.0 mm) to a length of about 5 mm.
The above-mentioned resist substrate was placed directly on the back side of a reticle with a line width of 10 μm at a distance of 0 cm, and a coherent ArP laser beam with a laser beam angle of 0.4 Mrad was applied at 0.
7 J/cm" irradiation. Next, a boost baking (170°C for 230 minutes) was performed and development was performed using a developer (isopropyl alcohol: MIBK = 7:3 volume ratio). As a result, a high-resolution pattern was obtained. The laser beam irradiation area was 10
It was observed that the viscosity average molecular weight was reduced by 3 orders of magnitude.

The absorption characteristics of this resist with respect to irradiation light are shown in FIG.

Example 2 A resist substrate obtained in the same manner as in Example 1 was used with X-rays (wavelength: 10 nm) using a beam diameter of 1.5° instead of an ArF laser.
Irradiation is focused on oX, and the line width is 1 with a secondary target of about 10 eV.
, 5ooX ultrafine patterns were obtained.

In the example, an example of a copolymer of methyl methacrylate and hexafluoroisopropyl methacrylate was shown, but tetrafluoroethyl methacrylate, tetrafluoroacrylate, hexafluoroisopropyl acrylate,
Hexafluorobutene-2, hexafluorobutadiene-1,
3. A resist thin film made of a copolymer of either hexafluoropropane and methyl methacrylate can be similarly used for ArP laser light and X-rays.

Further, the molar ratio C (1/M) between methyl methacrylate and hexafluoroisopropyl methacrylate is preferably 06 to 1.5, and particularly preferably 0.8 to 1.2. The molar ratio is 0.
If it is smaller than 6, the molecular weight will not increase, and the effect of photo-lowering after light irradiation cannot be obtained. When the molar ratio is larger than 5, the effect of fluorine, that is, the Machii acidity is lost.

Example 3 Methyl methacrylate (MMA) 5.34 ml (5,
00x 10”mol), hexafluoroisopropyl methacrylate) (HFIPMA) 11.86g (5,
Ox 10'-2 mol), phenyl methacrylate 0
．． 27 g (1,67x 103 mol) and benzoyl peroxide (BPO) 0.014 g (4,13x
Synthesis was carried out in the same manner as in Example 1, except that 103 mol # was put into the polymerization tube. The yield of the obtained polymer was 7
．． 0%, and the viscosity average molecular weight is M'v = 7.5
It was X 108. Using this polymer, a high-resolution resist pattern similar to that of Example 1 could be formed.

Further, even when irradiated with X-rays of 10 nm, an extremely fine pattern similar to that of Example 2 was obtained.

Example 4 Methyl methacrylate (MMA) 2.67 ml (2,
50
50x 10,"mol), 2-vinylnaphthalene O
,0,129 g'(8,33X10' mol) and benzoyl peroxide (BPO) 0.007 g (4,1
Synthesis was carried out in the same manner as in Example 1, except that 3X 103 mol/g) was placed in the polymerization tube. The yield of the obtained polymer was 6.4%, and the viscosity average molecular weight was M v =
It was 4.51×10'. Using this polymer, a high-resolution resist pattern similar to that of Example 1 could be formed.

Further, even when irradiated with X-rays of 10 nm, an extremely fine pattern similar to that of Example 2 was obtained.

(Effects) According to the ultra-polymer resist material of the present invention, a substrate can be coated with a thickness of 100OA (0.1μm), and 1O~
Extremely fine patterns can be formed by irradiation with light of 200 nm, ie, ArP excimer laser light, or light in the X-ray region.

In particular, in the X-ray region, ultrafine patterns can be formed using photoreactions caused by X-ray secondary electron collisions, regardless of resist film thickness dependence.

Furthermore, since it is a fluorine-containing polymer, it has excellent acid resistance against hydrofluoric acid.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing light absorption characteristics (transmittance) with respect to wavelength in Example 1.

Claims (3)

[Claims] (1) The main chain is essentially the following repeating unit ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, in the formula, R^1 and R^3 are hydrogen, methyl, or ethyl groups, and R^2 is Alkyl group having 1 to 6 carbon atoms, R^
4 is a fluorinated alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and l/
m=0.6 to 1.5. ) and a vinyl monomer having an aromatic ring or a heteroaromatic ring in the molecular skeleton, and has an average molecular weight of 5 x 10
A photoresist material characterized in that the size of the photoresist is ^5 to 5 x 10^7. (2) The main chain is essentially the following repeating unit ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, in the formula, R^1, R^3, R^5 are hydrogen groups, methyl groups, or ethyl groups, R^2 is an alkyl group having 1 to 6 carbon atoms, R^4 is a fluorinated alkyl group having 1 to 8 carbon atoms, in which at least one hydrogen atom is substituted with a fluorine atom,
R^6 has ▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲Mathematical formulas, chemical formulas, tables, etc.▼ Represents one of the following. ), and has an average molecular weight of 5 x 10^5 to 5 x 10^7. (3) The main chain is essentially the following repeating unit ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, in the formula, R^1, R^3 are hydrogen groups, methyl groups, or ethyl groups, R^2 is an alkyl group having 1 to 6 carbon atoms, R
^4 is a fluorinated alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is replaced with a fluorine atom, and R^5
There are ▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼ represents one of ferrocene. ) with an average molecular weight of 5×
10^5 to 5x10^7.