JPH05119477A - Photoresist intermediate and photoresist - Google Patents

Abstract

PURPOSE:To improve resolution by preparing a photoresist from a photoresist intermediate comprising a water-soluble polymer for water development and the aq. soln. of this intermediate and bichromate. CONSTITUTION:The photoresist for water development is prepared from the intermediate comprising a water-soluble polymer expressed by formula having 50000-120000 weight mean mol.wt. In formula, A is a hydrophobic monomer having a bulk functional group, x is 0.8-0.85, y is 0.1-0.15, and z is 0.01-0.05. The hydrophobic monomer is preferably t-butylacrylate, t-butylmethacrylate or isopropylacrylate. Namely, the photoresist intermediate is a water-soluble polymer comprising copolymers of vinyl alcohol, vinyl acetate, and hydrophobic monomers having bulk functional groups such as t-butylacrylate, etc. The vinyl alcohol is not crystallized and is very easily dissolved in water, so that dissolution proceeds in each single molecule. Thus, resolution can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an intermediate for a water-development type photoresist and an improvement in a water-development type photoresist obtained by directly using this intermediate. In particular, it relates to improvements that improve resolution.

[0002]

2. Description of the Related Art A photoresist used for etching a thick metal plate such as a lead frame or a shadow mask has a large resistance to an acid because its etchant is an acid. Therefore, a water-development type photoresist is used because the developer cost is low.

Typical examples of the water developing type photoresist according to the prior art are an aqueous solution of polyvinyl alcohol and dichromate, and an aqueous solution of casein and dichromate.

[0004]

In the conventional water-developing photoresist, the minimum space width of the line space pattern that can be formed using the photoresist is 20 μm.
Since it is about m, the resolution cannot be said to be sufficient. Moreover, in the case of an aqueous solution of casein and dichromate, there is a drawback that the sensitivity (the amount of light energy required to expose a unit thickness) varies greatly.

An object of the present invention is to eliminate these drawbacks, and to directly use a water-development type photoresist intermediate and its intermediate, which have advantages of excellent resolution and small variation in sensitivity. A water-developing photoresist is provided.

[0006]

Of the above objects, the first
Purpose (Provision of intermediate for photoresist of water development method)
Is the expression

[0007]

[Chemical 3] However, A is a hydrophobic monomer having a bulky functional group, x is 0.8 to 0.85, and y is 0.1 to 0.1.
5, and z is 0.01 to 0.05. And has a weight average molecular weight of 50,000 to 120,000.
And a water-developing intermediate for a photoresist, which comprises a water-soluble polymer.

T-butyl acrylate, t-butyl methacrylate, or isopropyl acrylate is suitable for the above hydrophobic monomer.

Among the above-mentioned purposes, the second purpose (providing a photoresist of water development type) is

[0010]

[Chemical 4] However, A is a hydrophobic monomer having a bulky functional group, x is 0.8 to 0.85, and y is 0.1 to 0.1.
5, and z is 0.01 to 0.05. And has a weight average molecular weight of 50,000 to 120,000.
Is achieved by a water developing type photoresist consisting of an aqueous solution containing 10 to 20% of a water-soluble polymer and 0.6 to 1.0% of dichromate.

As the above-mentioned hydrophobic monomer, t-butyl acrylate, t-butyl methacrylate or isopropyl acrylate is suitable. In addition, a preferable requirement for A as the above-mentioned hydrophobic monomer is that the three-dimensional shape has a bulky functional group. Therefore,
As long as this is satisfied, examples of A include a hydrophobic monomer having a branched alkyl group having 3 to 4 carbon atoms in the side chain.

[0012]

The present invention is based on the results of experiments, and the basis of its action is not always clear, but it is considered as follows.

In the polyvinyl alcohol according to the gist of the water-development type photoresist according to the prior art, the contained hydroxyl groups are bonded and the polyvinyl alcohol is crystallized, which is difficult to dissolve in water. The water-development type vinyl alcohol has a single hydroxyl group contained therein, and the vinyl alcohol is not crystallized,
It is extremely soluble in water, and as a result, the dissolution progresses for each single molecule, which improves the resolution. According to the experimental results, the minimum space of the line space pattern that can be formed using this photoresist. The width is 10 μm or less.

[0014]

EXAMPLES Hereinafter, the photoresist intermediates and photoresists according to the examples of the present invention will be described.

Example 1 (A is t-butyl acrylate) 78 g of vinyl acetate and 13 g of t-butyl acrylate
And 0.03 g of 2,2′-azobisisobutyronitrile functioning as a polymerization initiator, methanol 1,000
It was dissolved in ml and reacted under reflux and stirring in a nitrogen atmosphere at 60 ° C. for 15 hours to obtain a copolymer of vinyl acetate and t-butyl acrylate.

Next, 20 g of caustic soda was added to give 30
After stirring for 1 hour at ℃, saponification was performed to remove the solvent methanol,

[0017]

[Chemical 5] However, A is t-butyl acrylate, and the structural formula is represented by the following formula.

[0018]

[Chemical 6] A polymer represented by

The weight average molecular weight of the obtained polymer was about 1.2 × 10 ⁵ . The quantitative ratio of vinyl alcohol, vinyl acetate, and t-butyl acrylate, which are the respective constituent elements, was 0.82: 0.15: 0.03 as measured by elemental analysis and nuclear magnetic resonance. there were.

150 g of this polymer and 8 g of ammonium dichromate were dissolved in 1,000 ml of water to produce a water developing type photoresist according to this example. Spin coating this photoresist on a copper plate (350 rpm,
30 seconds) and then in a clean oven at 60 ° C for 30
After drying for a minute, a photoresist film having a film thickness of about 7 μm was formed.

After exposing using a 5 kW ultra-high pressure mercury lamp using a photomask to convert the exposed area to insoluble, water at room temperature is sprayed for 1 minute to dissolve and develop the unexposed area. I went. It was confirmed that the minimum space width of the line space pattern measured after drying was about 10 μm, the pattern shape was accurate, and the variation in sensitivity was small.

Second embodiment (example in which A is t-butyl methacrylate) 78 g of vinyl acetate and 14 g of t-butyl methacrylate
And 0.03 g of 2,2′-azobisisobutyronitrile functioning as a polymerization initiator, methanol 1,000
It was dissolved in ml and reacted in a nitrogen atmosphere at 60 ° C. for 10 hours under reflux and stirring to obtain a copolymer of vinyl acetate and t-butyl methacrylate.

Next, 20 g of caustic soda was added to obtain 30
After stirring for 1 hour at ℃, saponification was performed to remove the solvent methanol,

[0024]

[Chemical 7] However, A is t-butyl methacrylate, and the structural formula is represented by the following formula.

[0025]

[Chemical 8] A polymer represented by

The polymer obtained has a weight average molecular weight of about 9
It was × 10 ⁴ . The quantitative ratio of vinyl alcohol, vinyl acetate and t-butyl methacrylate, which are the respective constituent elements, was 0.81: 0.14: 0.05 when measured using elemental analysis and nuclear magnetic resonance. there were.

150 g of this polymer and 8 g of ammonium dichromate were dissolved in 1,000 ml of water to prepare a water developing type photoresist according to this example. Spin coating this photoresist on a copper plate (350 rpm,
30 seconds) and then in a clean oven at 60 ° C for 30
After drying for a minute, a photoresist film having a film thickness of about 5 μm was formed.

After exposing the exposed area to insolubility using a 5 KW ultra-high pressure mercury lamp using a photomask, water at room temperature is sprayed for 1 minute to dissolve the unexposed area for development. I went. It was confirmed that the minimum space width of the line space pattern measured after drying was about 10 μm, the pattern shape was accurate, and the variation in sensitivity was small.

Third Example (example in which A is isopropyl acrylate) 78 g of vinyl acetate and 11 g of isopropyl acrylate
And 0.03 g of 2,2′-azobisisobutyronitrile functioning as a polymerization initiator, methanol 1,000
It was dissolved in ml and reacted in a nitrogen atmosphere at 60 ° C. for 10 hours under reflux and stirring to obtain a copolymer of vinyl acetate and isopropyl acrylate.

Next, 20 g of caustic soda was added to obtain 30
After stirring for 1 hour at ℃, saponification was performed to remove the solvent methanol,

[0031]

[Chemical 9] However, A is isopropyl acrylate, and the structural formula is represented by the following formula.

[0032]

[Chemical 10] A polymer represented by

The weight average molecular weight of the obtained polymer was about 1.1 × 10 ⁵ . The quantitative ratio of vinyl alcohol, vinyl acetate, and isopropyl acrylate, which are the respective constituent elements, was 0.84: 0.14: 0.02 when measured using an elemental analysis method and a nuclear magnetic resonance method. .

150 g of this polymer and 8 g of ammonium dichromate were dissolved in 1,000 ml of water to produce a water developing type photoresist according to this example. Spin coating this photoresist on a copper plate (350 rpm,
30 seconds) and then in a clean oven at 60 ° C for 30
After drying for a minute, a photoresist film having a film thickness of about 6 μm was formed.

After exposing the exposed area to insolubility using a 5 kW ultra-high pressure mercury lamp using a photomask and spraying room temperature water for 1 minute, the unexposed area is dissolved and developed. I went. It was confirmed that the minimum space width of the line space pattern measured after drying was about 10 μm, the pattern shape was accurate, and the variation in sensitivity was small.

[0036]

As described above, the intermediate for photoresist according to the present invention is a water-soluble copolymer which is a copolymer of vinyl alcohol, vinyl acetate and a hydrophobic monomer having a bulky functional group such as t-butyl acrylate. Is a polymer,
Vinyl alcohol and vinyl acetate are aqueous solutions of this intermediate and dichromate, and the vinyl alcohol contained in the constituents of the above copolymer is not crystallized and is very easily soluble in water, and monomolecular Since the dissolution progresses every time, the resolution is greatly improved, and according to the result of the experiment,
The minimum space width of the line space pattern that can be formed using this photoresist is 10 μm or less. Further, it does not cause variations in sensitivity unlike a photoresist formed of an aqueous solution of casein and dichromate, and functions as an excellent intermediate for a photoresist of a water developing method and a photoresist of a water developing method. .

Continuation of front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H05K 3/06 H 6921-4E (72) Inventor Katsumasa Kawashima 1-5-1 Taito, Taito-ku, Tokyo Toppan In Printing Co., Ltd. (72) Inventor Shoji Yonezawa 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd.

Claims (4)

[Claims] 1. The formula: However, A is a hydrophobic monomer having a bulky functional group, x is 0.8 to 0.85, y is 0.1 to 0.15, and z is 0.01 to 0.05. is there. And has a weight average molecular weight of 50,000 to 12
A water-developing intermediate for photoresists, which is composed of a water-soluble polymer having a molecular weight of 10,000. 2. The water-developing intermediate for a photoresist according to claim 1, wherein the hydrophobic monomer is t-butyl acrylate, t-butyl methacrylate, or isopropyl acrylate. 3. The formula: However, A is a hydrophobic monomer having a bulky functional group, x is 0.8 to 0.85, y is 0.1 to 0.15, and z is 0.01 to 0.05. is there. And has a weight average molecular weight of 50,000 to 12
A water-development type photoresist, comprising an aqueous solution containing 10 to 20% of a water-soluble polymer of 20,000 and 0.8 to 1.0% of dichromate. 4. The photoresist according to claim 3, wherein the hydrophobic monomer is t-butyl acrylate, t-butyl methacrylate, or isopropyl acrylate.