JPH0213955A - Photoetching method - Google Patents

Abstract

PURPOSE:To improve the coating and the adhesive properties of a photoresist against a metal thin layer or a metal oxide thin layer by forming the metal thin layer or the metal oxide thin layer on the surface of a substrate plate, and then by mounting a protective film composed of a soluble substance on the surface of the metal thin layer or the metal oxide thin layer, followed by applying the photoresist on the protective film. CONSTITUTION:The metal thin layer or the metal oxide thin layer is formed on the surface of the substrate plate, and then, the protective film composed of the soluble substance is mounted on the surface of the metal thin layer or the metal oxide thin layer, followed by applying the photoresist on the protective film. The protective film material is preferably exemplified by an org. compd. such as a water-soluble resin, an alkali-soluble resin, a nonionic surfactant, a cationic surfactant, an aromatic carboxylic acid, a hydoxy alkyl carboxylic acid, a hydroxyphenyl carboxylic acid, an org. phosphoric acid compd. and an amide compd., etc. Thus, the coating property of the photoresist is stable, and a photoresist film having a less generation of a pin hole is formed, and the peeling and the side etching properties of the resist film are improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a photoetching method used in the manufacturing process of semiconductor devices and electronic components such as liquid crystal display devices, fluorescent display tubes, thermal heads, and image sensors. In particular, the present invention relates to a photoetching method that has simplified steps and is suitable for microfabrication.

(Prior art) In the method of photoetching a single layer of metal or metal oxide formed on the surface of a substrate by a method such as vapor deposition, sputtering, CVD, or plating, the coating is usually Clean the surface of the etching film before use.

This cleaning not only removes dirt adhering to the surface, but also, rather importantly, removes impurities formed by oxidation, improves the wettability of the photoresist, and ensures uniform, good adhesion and no defects. No photoresist layer has been done to form. Therefore, a process including a step in which the surface of the film to be etched is slightly etched is carried out, but it has the disadvantage that the process becomes complicated.

Furthermore, since such cleaning involves treatment with a strong acid or strong alkaline solution, it is not favorable in terms of the working environment, and waste liquid treatment costs are high.

(Problems to be Solved by the Invention) Accordingly, it is an object of the present invention to provide a photoetching method that provides excellent coatability and improved adhesion of a photoresist to a metal or metal oxide thin layer.

Another object of the present invention is to provide a photoetching method that simplifies the process of cleaning a substrate to be etched before applying photoresist, improves the working environment during the cleaning process, and reduces the cost of cleaning waste liquid treatment. shall be.

(Means for Solving the Problem) In the present invention, if the surface of the uncontaminated film to be etched immediately after being formed is covered with a protective film, the surface of the film to be etched can be easily removed by simply removing the first protective film immediately before use. This was done based on the knowledge that a coated surface to be etched without etching can be obtained.

That is, an object of the present invention is to apply a photoresist to a metal or metal oxide thin layer, expose and develop it, and form a pattern of the metal or metal oxide thin layer. Alternatively, after forming a metal oxide thin layer and before applying a photoresist, a protective film made of a soluble substance is provided on the surface of the metal or metal oxide thin layer. Achieved from 1.

The protective film material of the present invention includes water-soluble resin, alkali-soluble resin, nonionic surfactant, cationic surfactant,
Aromatic carboxylic acids, hydroxyalkyl carboxylic acids, hydroxyphenyl carboxylic acids, phosphoric acid compounds,
Organic compounds such as amide compounds, aromatic amines, hydroxyalkylamines, N-containing heterocyclic compounds, and aliphatic alcohols are useful.

Specifically, PVA, casein, polyacrylamide,
Water-soluble resins such as acrylamide copolymers, polyacrylic acid, acrylic acid copolymers, phenol resins, rosin and its modified products, alkali-soluble resins such as acrylic acid copolymers (M resins, alkyl BH esters, Alkylbenzene sulfonate, alkylnaphthalene sulfonate, dialkyl sulfosuccinate ester salt, alkyl phosphate ester, naphthalene sulfonic acid formalin condensation 1, anionic surfactants such as polyoxyethylene alkyl sulfate, polyoxyethylene alkyl ether,
Polyoxyethylene alkylphenol ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester,
Nonionic surfactants such as glycerin fatty acid esters and oxyethylene oxypropylene block copolymer, cationic surfactants such as alkylamine salts, quaternary ammonium salts, and polyoxyethylene alkylamines, propionic acid, butyric acid, valeric acid, and caproic acid. , saturated or unsaturated aliphatic carboxylic acids such as heptanoic acid, caprylic acid, nonanoic acid, decanoic acid, oleic acid, stearic acid, saturated or unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, succinic acid, etc. Aromatic carboxylic acids such as citric acid, tartaric acid, lactic acid, malic acid, ascorbic acid, salicylic acid, gallic acid, etc. Organic phosphoric acids such as hydroxyphenylcarboxylic acids, phytic acid, etc., or amide compounds of the above carboxylic acids, saturated or unsaturated alkylamines such as propylamine, butylamine, hexylamine, heptylamine, octylamine, stearylamine, etc. Compatible or unsubstituted aromatic amines such as aniline, toluylamine, dialkylaniline, hydroxyalkylamines such as ethanolamine and propatoolamine, urea,
N such as alkyl urea or aralkylurea, benzimidazole, benzoxazole or benzthiazole
-containing heterocyclic compounds, aliphatic alcohols, etc.

The overcoat can be applied from a solution of the overcoat material in a suitable solvent. Carboxylic acids can also be used as metal salts such as sodium or potassium salts or salts of various amines. Similarly, organic amines can also be used as various inorganic acids or organic acid salts. These compounds can be used alone or in combination. When a metal or metal oxide layer is formed by wet processing, a protective film may be applied after drying by a conventional method, or a protective film may be applied while the surface is not dry.

A preferable example is to immerse the material in a solution of the protective film material without drying it, and then dry it by nipping it with a roller to leave an appropriate amount of the protective film, or to continue immersing it in a solution of the protective film material at a certain concentration. , nipping with rollers, etc. may be repeated.

When applying the protective film in a dry state, methods such as roller coating, dip coating, spray coating, beat coating, spin coating, and curtain coating can be used.

The amount of application is not particularly strict, but it is 20mg to 50g/m2
It is preferable to use a protective film and dry products that can be stored for a long period of time. Furthermore, if the location where the resist is applied is far away, it can be packaged and transported.

In either case, the resist can be applied simply by washing off the protective film. The adhesiveness of the resist applied through such a process is stable and has excellent adhesive strength.

The t'A3u film may simply form a film on the surface, or may combine with a metal or metal acid arsenide thin layer to form a passivation layer on the surface of the metal or metal oxide thin layer. ,
The latter more effectively improves the adhesion of the photoresist. Similarly, when an adhesion aid as disclosed in Japanese Patent Application No. 62-266921 is added to 1VILi, the effect becomes even greater.

These resistors 31 are removed before, preferably immediately before, applying the photoresist, but it is also possible to apply the photoresist 1 without removing them. In this case, garbage 1
Although it is a necessary condition that there is no tightness, the applicability and adhesion may actually be improved.

Although the method of the present invention does not limit the type of metal or metal oxide thin layer, the most frequently used materials are
These thin layers are usually glass,
It is a thin film formed on an insulating substrate such as a polyester film or ceramic by vapor deposition, plating, or coating.

It is used in compositions such as metals or single oxides of Ti, Ge, Sn, Pb, Sb, Ga, AI, Si, or mixtures of some or their acids and arsenides.

In particular, oxides of In and Sn alloys are important as transparent electrodes.

As the photoresist used in the present invention, a positive photoresist made of an O-quinonediazide compound and a phenol resin is useful. The most common 0-quinonediazide compound is 1,2-naphthoquinone-2-diazide-5-sulfonic acid ester of trihydroxybenzophenone, but the present invention is not limited thereto.
For example, Japanese Patent Publication No. 43-28,403, U.S. Patent No. 2.
No. 754.209, No. 3,046,110, No. 3,0
No. 46.112, No. 3,046,113, No. 3.,0
46.116, 3,046,118, 3,04
6.119, 3,046,120, 3,647
．． Also useful are those disclosed in No. 443 and No. 3,759,711. Among these, 2.
3.4.4°-tetrahydroxybenzophenone, 2.
3.4.2', 6°-pentahydroxybenzophenone, 2,4,6.3', 4', 5°-hexahydroxybenzophenone, 2,3,4.5,4°-pentahydroxybenzophenone, etc. 1 ,2-naphthoquinonediazide-
(or -4) sulfonic acid esters are preferred.

The alkali-soluble phenolic resin that is the binder component of Fut I/Resist is, for example, [Synthetic Resin in Corteindus] ("5 Synthetic Resin").
Re5in inCoatings” (H,P,P
by Noyes Development
Cor-poration, 1965. Pearl
Preferred are novolac or resol resins, which are phenol/formaldehyde resins, such as those described in Chapter 15 of the American Journal of the American Society for the Study of Materials and Drugs, Inc., published by J.D. Ri-Ver, New York). Novolac resins are synthesized by the condensation of phenolic compounds and aldehydes under acid catalysts, and resol resins are synthesized under basic catalysts.In addition to phenol,
Cresol, xylenol, ethylphenol, butylphenol, isopropylmethyl-oxyphenol, chlorophenol, hydroquinone, naphthol, 2.2-
Those using bis(p-hydroxyphenol)propane or the like can also be used.

The photosensitive composition is generally used in the form of a solution by dissolving it in an organic solvent. It is used at a solid content concentration of 10 to 80%, preferably 20 to 60%. The solvent is
It is desirable to have a solution that dissolves each component uniformly and has an appropriate boiling point.Also, other melting points may be selected depending on the wettability, spread, surface quality, etc. of the solution when applied with a spinner, etc. Examples of typical solvents are shown below, which can be used alone or in combination. Namely, glycol ether-based methyl cellosolve, ethyl cellosolve, propyl cellosolve, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether and their acetylated products, sunawachi, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate. , propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate I.
is useful. In addition, acetate esters include amyl acetate, butyl acetate, propyl acetate, and ethyl acetate.
Methylpyrrolidone, gamma-butyrolactone, ethyl lactate, and the like are useful, where the alkyl group can be straight chain or branched.

After drying, the metal or metal oxide thin layer from which the protective film has been removed is coated with the above-mentioned photoresist composition to a thickness of several microns using a roll coater, spinner, or sprayer, and exposed, developed, and exposed by conventional methods. It is processed into the desired pattern through an etching process.

(Effects of the Invention) According to the present invention, a photoresist film with stable coating properties and fewer pinholes is formed. In addition, resist bleeding and side etching are improved, making it possible to perform precision photo etching where patterns become more complex, denser, and finer. This also allows for wider control of etching solution concentration and temperature. The range of baking temperature conditions can be expanded.

In addition, it is possible to select strong etching agents and processing conditions that increase the processing/etching speed, so that cleaning of the metal or metal oxide thin layer before coating the photoresist can be performed using P:I. It can be converted into butyric acid, eliminating the need for cleaning agents such as strong acids and strong bases, which improves the working environment and reduces waste acid treatment costs.

The present invention will be explained below with reference to Examples.

(Example) Example 1 and Comparative Examples 1 and 2 10100x10 with ITO vapor deposited film of 5'0OOA
Three glass substrates of No. 0 were prepared. They are respectively referred to as a) (Example 1), b) (Comparative Example 1), and c) (Comparative Example 2). a
) was immersed in a solution of urea Log and PVA (Kuraray product PVA-205>Log dissolved in 1000 ml of pure water) immediately after it was taken out of the Pelger.The temperature of the solution was 25°C. .The board taken out after 1 minute,
After passing it between two rubber rollers and squeezing to remove excess liquid, it was air-dried and left indoors for one week. b
) and C) were taken out of the Pelger and left indoors with a commonly used mount in between. After 1 week, b) is Na
Immersed in 0.1% aqueous solution of OH for 25'C51 min,
It was washed with pure water and dried with hot air. A) and C) were washed with pure water for 1 minute and then dried with hot air. Its f&a>, b), c)
The three samples are positive photoresist 1~ (composition: l
・A solution of 8% 1,2-naphthoquinone-2-diazide-5-sulfonic acid ester of lyhydroxybenzophenone, 25% cresol formaldehyde resin, and 67% cellosolve acetate was applied using a roller coater (manufactured by Dainippon Screen). It was applied to a film thickness of 1.5 microns. Sample C) had noticeable coating streaks, and pinholes were partially observed along the coating streaks.

For these samples, CANON PLA 501
After exposure with a soft contact using a contact aligner, it was immersed in a 0.5% NaOH aqueous solution for 60 seconds and developed.

Etching is HCI (35%): FeClr (
40' Be): This was done by preparing pure water at a volume ratio of 4+1:5 and immersing it in a solution at 40°C for 5 minutes (
In order to make it easier to confirm the effect, the test was carried out under harsh conditions.

Subsequently, the resist was washed red by immersion in acetone.

The amount of side etching of the ITO film was as shown in Table 1. Sample a) prepared by the method of the present invention has both side etch and wettability, and sample b prepared based on the conventional method.
), the same or better performance was obtained.

Method a) does not use an alkaline etching agent, so it has the advantage of improving the working environment and eliminating the need for waste liquid treatment.

Example 2 and Comparative Example 3.4 100xlOOm m with 6500A AI vapor deposited film
Three glass substrates were prepared. e) (Example 2)
), f) (Comparative Example 3), and g) (Comparative Example 4). e
) is immersed in a solution of 2 g of butylamine and 10 g of casein dissolved in 10100 O pure water immediately after it is removed from the Pelger. The temperature of the solution was 25°C. After 1 minute, the substrate was taken out, hung on a string to air dry, and then left indoors for one week. After removing f) and g) from the Pelger, they were left indoors with a mount in between. After one week, f) in a 0.1% aqueous solution of H2SO2 at 35 °C11
It was soaked for a minute, washed with pure water, and dried with hot air. e) and g)
was washed with pure water for 1 minute and then dried with hot air. the fee)
The three samples of , f) and g) are positive photoresists (composition: 1 to 1,2-naphthoquinone-2-diazide-5-sulfonic acid ester of lyhydroxybenzophenone 8
%, cresol formaldehyde resin 25% and cellosolve acetate 67%) solution was applied using a roller coater (manufactured by Dainippon Screen) to a film Jf of 1.5 microns. In sample g), leveling was insufficient and coating streaks were visible.

For these samples, CANON PLA 501
After exposure with soft contacts 1 to 1 using a contact aligner, it was immersed in a 0.5% aqueous solution of NaOH for 60 seconds and developed.

Etching is H) PO4: CH3CO0H: HCl
:H2O in a volume ratio of 16:2:1:1 and immersed in a solution at 55° C. for 5 minutes (to make it easier to confirm the effect, the test was carried out under harsh conditions).

Subsequently, the resist was peeled off by immersion in acetone. AI
The amount of side etching of the film was as shown in Table 1. Sample e) prepared by the method of the present invention had performance equivalent to or better than sample f) prepared based on the conventional method in both side etch and wettability.

Example 3 and Comparative Examples 5 and 6 10100x100 with 7500A Ni plating film
Three glass substrates were prepared. 1) (Example 3)
), m) (comparative example 5), and n) (ratio axis example 6). l)
was removed from the plating bath, washed with water, and immediately immersed while still wet in a solution of 6.5 g of citric acid and 5 g of carboxymethyl cellulose (molecule i5000) dissolved in 10100O pure water. The temperature of the solution was 25°C. 1
After a few minutes, the substrate was taken out, hung on a string, air-dried, and left indoors for one week. m) and n) were removed from the plating bath, washed with water, dried, and left indoors with a mount in between for 61 weeks.
The mixture was crushed for 11 minutes at °C, washed with pure water, and dried with hot air. 1
) and n) were washed with pure water for 1 minute and then dried with hot air. Thereafter, the three samples 1), m), and n) were coated with positive photoresist in the same manner as in Example 1, and exposed and developed.

Etching is HNO,: CH, C0OH: ) (20
were prepared in a volume ratio of 1:1:1 and immersed in a solution at 40°C for 5 minutes (to make it easier to confirm the effect, the test was carried out under harsh conditions).

Subsequently, the resist was removed by immersion in acetone. N
The amount of side etching of the i-film was as shown in Table 1. Sample l) prepared by the method of the present invention has both side etching and wettability, and sample m) prepared based on the conventional method.
The same or better performance was obtained compared to .

Example 4 and Comparative Example 7.8 10100xlO with 5000A 5iO211N
Three O glass substrates were prepared. They are respectively referred to as 0) (Example 4), p) (Comparative Example 7), and q) (Comparative Example 8). 0
) was coated with a solution prepared by dissolving 8 g of Zanisol C (Kao A) (manufactured by Rastsuji: alkylbenzyldimethylammonium chloride) in 10100O pure water.

V5 temporary was hung on a string to air dry and left as it was indoors for a week. 60) and q) were taken out of the Pelger and left indoors with a mount in between. One week later, p> was immersed in a 0.1% aqueous solution of NaOH at 25° C. for 1 minute, washed with pure water, and dried with hot air. Samples 0) and 9) were washed with pure water for 1 minute and then dried with hot air.

Thereafter, the three samples o), p), and q> were coated with a positive type 7-year-old I resist in the same manner as in Example 1, exposed to light, and developed.

Etching uses HF:HNO3:H2O at a volume ratio of 1:2.
(To make it easier to confirm the effect, the test was carried out under harsh conditions.)

Subsequently, the resist was peeled off by immersion in acetone. 5i
Table 1 shows the amount of side etching of the N2 film. Samples prepared by the method of the present invention 0) Table 1 ◎: Good for the first time Wounds: Blurred edges ○: Good Δ: Slightly uneven Compared to the sample ρ) created based on the method, the same or better performance was obtained.

Claims (1)

[Claims] Applying photoresist to a thin layer of metal or metal oxide;
In a photo-etching method for forming a pattern of a metal or metal oxide thin layer by exposure and development, after forming a metal or metal oxide thin layer on the substrate surface, the metal or metal is removed before applying a photoresist. A photoetching method characterized by providing a protective film made of a soluble substance on the surface of a thin oxide layer.