JPH0862847A - Positive photosensitive composition - Google Patents

Abstract

PURPOSE: To improve adhesion to a substrate, to enhance the precision of over- etching and to faithfully transfer a fine pattern to the substrate by incorporating an alkali-soluble phenolic resin, an o-quinonediazido compd., a specified solvent and a specified compd. CONSTITUTION: This photosensitive compsn. contains an alkali-soluble phenolic resin (a), an o-quinonediazido compd. (b), a compd. (c) represented by the formula and a solvent (d) having ability to well dissolve the components (a)-(c). In the formula, X is S or O, at least one of R1 -R4 is a cyclohexyl ring, a morpholine ring or alkyl having a cyclohexyl ring or a morpholine ring and each of the others is H, alkyl or aryl. Since at least one kind of compd. (c) having at least one cyclohexyl or morpholine ring in one molecule is used, the adhesion or adhesiveness of a resist to a substrate is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel positive-type photosensitive composition, and more specifically, resolution, sensitivity and adhesion used in the production of electronic parts such as semiconductor devices and liquid crystal display devices. The present invention relates to a positive photosensitive composition having excellent developability and suitable for fine processing.

[0002]

2. Description of the Related Art Conventionally, the photofabrication process in the manufacture of highly integrated circuit devices such as LSIs or the manufacture of liquid crystal display device circuits, etc.
A photosensitive composition is formed on the surface of a large number of substrates such as glass substrates and ceramic substrates on which various metal films or conductive films are formed by a spin coating method or a roller coating method. The target circuit pattern image is formed by irradiating the film with an actinic ray to form an image. Here, particularly in the case of a fine circuit element, a desired circuit pattern is obtained after this by processing the metal film or the conductive film.

In order to form such a fine pattern, the photosensitive composition is mainly composed of an alkali-soluble novolac resin generally called a phenol resin and two components of a photosensitive material having a naphthoquinonediazide group as a photosensitive group. What you do is commonly used. Using such a photosensitive composition (hereinafter also referred to as a resist), from an ultra-fine image pattern size of about 0.3 μm to a considerably large size range of several tens to several hundreds μm. Images of a wide range of dimensions are formed, enabling fine processing of various substrates.

The circuit line width of integrated circuit semiconductors is becoming finer as the degree of integration becomes higher, and the line width is expanding from submicron to half micron. On the other hand, in liquid crystal display devices and the like, the line width also becomes thin and tends to become finer.
The control of the design line width is based on the control of the pattern line width in image formation and the dimension control in etching. In particular, in the processing of a high resolution resist pattern accompanying the miniaturization of the design line width, the resolution and the adhesion of the resist to the substrate during etching are important factors for improving the processing accuracy. In particular, in the wet etching method, it is no exaggeration to say that this adhesion controls the accuracy of the substrate processing technology, and has a great influence.

On the other hand, in relation to liquid crystal display elements, new base metal materials have come to be used, and color ST
With the development of N or TFT display elements, the ITO film, which has a long track record as a transparent conductive film, is being made to have lower resistance, that is, thicker film. In order to deal with the etching of thick ITO, it is necessary to perform the treatment for a longer time than the conventional overetching treatment time. For this reason, at the adhesion level that can be used without any problems in the past, in etching a finer pattern, the amount of side etching becomes large, which causes peeling of the fine resist pattern. Therefore, it has been found that a microetching pattern of a predetermined size cannot be obtained, and the demand cannot be sufficiently satisfied. A higher level of adhesion has come to be required.

Representative examples of the substrate used in the liquid crystal display element include ITO, Ta, Mo, Cr and a nitride film. Similarly to the semiconductor element, dry etching or wet etching is performed using the resist wiring pattern formed on these underlying substrates as a protective film.
Since the processing accuracy in etching has a great influence on the device performance, it is necessary to perform the etching process with higher accuracy. For this purpose, it is important that the adhesion of the resist to the substrate is high during the etching process. That is, there is a demand for a resist having a small side etch amount.

In response to such a request, Japanese Patent Laid-Open No. 2-846
No. 54, 2 of quinonediazide / phenolic resin
It is disclosed that the adhesion to various substrates, especially ITO substrates can be improved by adding at least one compound of a urea compound, a thiourea compound and an arylamine compound to a positive resist composed of an original system. However, the technology of liquid crystal display devices is moving toward the development of monochrome and color, small to large, and easy-to-see, fast-response devices that provide clearer images. It is necessary to use a substrate having a conductive film of. In order to increase the processing accuracy, in order to improve the etching accuracy such as in-plane uniformity, the reason for thickening the substrate and increasing the size is
The over-etching process must be performed for a fixed time longer than before. Therefore, in order to cope with this over-etching, the substrate adhesion of the resist film needs to exceed the conventional required level. However, JP-A-2-846
Although the technique disclosed in Japanese Patent No. 54 is at a level that can satisfy the conventional requirements, it is becoming difficult to satisfy the requirement level corresponding to new movements.
For example, good results can be obtained by etching near room temperature, but when etching is performed at a relatively high temperature for a long time, the side etch amount tends to be large and the adhesiveness tends to deteriorate.

[0008]

In the present invention, the adhesion to the substrate is much higher than in the prior art, the processing accuracy is improved even in the etching treatment, particularly the overetching treatment, and a finer pattern is faithfully transferred to the substrate. It is an object of the present invention to provide a positive-type photosensitive composition capable of being processed.

[0009]

[Means for Solving the Problems] An alkali-soluble resin,
In a positive resist containing two components of a photosensitive compound having a naphthoquinonediazide group as a photosensitive group in its molecule as a main component, JP-A-2-84654 discloses that urea and thiourea compounds are effective for improving adhesion. Disclosed. However, as a result of diligent studies in the present invention, it has been found that among these, the effects are different, and the level of the contributing effect is different depending on the difference in the substituents in the molecule.

That is, the present invention has the following structure. (A) Alkali-soluble phenolic resin (b) O-quinonediazide compound (c) Solvent having sufficient ability to dissolve the above-mentioned (a), (b) and the following (d) (d) Represented by the following general formula (I) A positive photosensitive composition comprising at least the compound described above.

[0011]

Embedded image

In the formula (I), X represents a sulfur atom or an oxygen atom, and at least one of R ₁ , R ₂ , R ₃ and R ₄ has a cyclohexyl ring, a morpholine ring, or a cyclohexyl ring or a morpholine ring. It represents an alkyl group, and the remaining ones each represent a hydrogen atom, an alkyl group or an aryl group. In the positive photosensitive composition of the present invention,
Addition of at least one compound represented by the general formula (I) having at least one cyclohexyl ring or morpholine ring in the molecule significantly improves the adhesiveness or adhesiveness of the resist to the substrate. Based on this new finding, the present invention has been accomplished. However, there is no suggestion of this finding in JP-A-2-84654.

The present invention will be described in detail below. The alkali-soluble resin used in the present invention contains novolac resin, vinylphenol resin, N- (hydroxyphenyl) maleimide copolymer, styrene-maleic anhydride copolymer, carboxyl group, sulfonyl group, or phosphonic acid group. Examples thereof include methacrylic resin and acrylic acid-based resin. Examples of alkali-soluble phenolic resins include "Synthetic Resin in Coat
ings "(HP Press by Noyes Development Corporation.
1965, Pear River NY) and the phenol / formaldehyde condensate novolac or resol resin described in Chapter 5. In the present invention, novolac resin is more preferable. The use of this is preferable in terms of good acid resistance, dry etching resistance, and heat resistance.

Novolak resins include phenols such as phenol / p-chlorophenol, o-cresol, p
-Cresols such as cresol and m-cresol, or xylenols such as 2,3-dimethylphenol, 2,4-dimethylphenol, 3,4-dimethylphenol and 3,5-dimethylphenol, alone or in combination of two or more. It can be obtained by addition polymerization of 1 to 0.6 mol of aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde or furfural in the presence of an acid catalyst to 1 mol of the combination of the above. Generally, hydrochloric acid, sulfuric acid, formic acid, oxalic acid and acetic acid are used as the acid catalyst. Among the above novolac resins, phenol novolac resins and cresol novolac resins are more preferable. As a result, in addition to acid resistance, heat resistance and dry etching resistance, resolution, cross-sectional shape and the like are improved. The thus obtained novolak resin having a molecular weight of 1000 to 50000 exhibits alkali solubility and can be used in the present invention. However, practically, it is preferably about 1000 to 30000. In the present invention, the above alkali-soluble phenol resin may be used alone or as a mixture of two or more kinds.

The photosensitive compound used in the present invention is o-
It is a quinonediazide compound, and is a compound containing a quinonediazide group as a photosensitive group in its molecule. Examples of the compound containing such a quinonediazide group as a photosensitive group in the molecule include 2,3,4-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,
4,4'-trihydroxybenzophenone, 2,3
Polyhydroxybenzophenone such as 4,4'-tetrahydroxybenzophenone or 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,3,4,3', 4 ', 5'-hexahydroxybenzophenone and polyhydroxy Phenyl alkyl ketones, bis (polyhydroxyphenyl) alkanes, polyhydroxybenzoic acid esters, bis (polyhydroxybenzoyl) alkanes or bis (polyhydroxybenzoyl)
A mixture of fully substituted and partially substituted products of an esterification reaction product of aryls with 1,2-naphthoquinonediazide-5 (and / or -4) -sulfonyl chloride, and also in JP-A-64-76047. As described above, a mixture of fully and partially substituted products of an esterification reaction product of the polyhydroxyspirobiindane compound and the sulfonyl chloride, and the triphenylmethane-based polyhydroxy compound and the sulfonyl described in JP-A-1-189644. As an example, a mixture of fully and partially substituted products of an esterification reaction product with chloride can be mentioned. In addition to this, as an example of a polyhydroxy compound, JP-A-4-27
Although those described in No. 4243 and the like can be given as an example, of course, the present invention is not limited to those exemplified here.

These quinonediazide compounds may be used alone or in combination of two or more. o
The quinonediazide compound is used in an amount of 5 to 100 parts by weight, preferably 5 to 60 parts by weight, based on 100 parts by weight of the alkali-soluble phenol resin. By adjusting the amount of the compound to be mixed in the range of 5 to 60 parts by weight,
The dissolution inhibiting effect can be more sufficiently obtained, and the film loss of the unexposed portion during development can be further suppressed. Therefore, it is possible to form a better profile pattern without causing any inconvenience such as deterioration of the profile that accompanies a decrease in the residual film rate. In addition, practical sensitivity can be obtained, and an extreme decrease in sensitivity can be eliminated. In addition, there is no instability factor such as re-precipitation that occurs when the amount exceeds the appropriate range, and stable storage is possible even after long-term storage.

In the present invention, in addition to the above alkali-soluble phenol resin and o-quinonediazide compound,
As the component, at least one compound selected from the group consisting of urea, thiourea, and derivatives thereof having at least one of the cyclohexyl ring and the morpholine ring represented by the above general formula (I) is added. By adding this component, the substrate can be processed with high accuracy. In the general formula (I), at least one of R _{1 to} R ₄ is a cyclohexyl ring, a morpholine ring,
Or represents an alkyl group having a cyclohexyl ring or a morpholine ring. Here, the alkyl group has one of 6 to 6 carbon atoms, and at least one hydrogen atom thereof is substituted with a cyclohexyl ring or a morpholine ring. In the present invention, the cyclohexyl ring, morpholine ring, or cyclohexyl ring- or morpholine ring-containing alkyl group is contained in the compound of the general formula (I) in an amount of 1 or more, preferably 3 or less. It is not clear why the compound has a function of improving adhesion by having a cyclohexyl ring or a morpholine ring. Perhaps, when the resist is formed on the substrate, the hydrophobic effect that they have has a function of suppressing the intrusion of the etchant into the organic film, so that the progress of the side etching is suppressed and the so-called adhesion is improved. It is estimated that it will be.

Examples of these compounds of the general formula (I) are 1-cyclohexyl-3- (2-morpholinoethyl) -2-thiourea and 1-cyclohexyl-3- (2
-Morpholinoethyl) -2-urea, cyclohexylthiourea, cyclohexylurea, 1,1'-dicyclohexylthiourea, 1,1'-dicyclohexylurea, 1,3-dicyclohexyl-2-thiourea, 1,
3-dicyclohexyl-2-urea, 1- (2-chloroethyl) -3-cyclohexyl-1-nitrosourea,
4,1- (2-chlorophenyl) -3-cyclohexylurea and the like can be mentioned as an example. However, the content of the present invention is not limited to these.

The compound represented by the general formula (I) is usually 0.01 to 100 parts by weight based on the total solid content of the alkali-soluble phenol resin and the o-quinonediazide compound.
It is preferably used in the range of 15 parts by weight. More preferably, it is in the range of 0.05 to 10 parts by weight. When the content is within these ranges, the above-mentioned effects of the present invention are more remarkably expressed. That is, the adhesion between the coating layer of the photosensitive composition and the substrate becomes better, and the stability of the photosensitive composition in solution becomes better.

Further, in the photosensitive composition of the present invention, as the solvent having the ability to sufficiently dissolve the alkali-soluble phenol resin, the o-quinonediazide compound, and the compound represented by the general formula (I), conventional solvents can be used. Many of the organic solvents used in the naphthoquinonediazide positive resist can be used. For example, glycol ether-based methyl cellosolve, ethyl cellosolve, propyl cellosolve, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether and acetylated products thereof, that is, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, propylene. There are glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, and the like. The acetic ester type includes amyl acetate, butyl acetate, propyl acetate, methyl acetate, ethyl acetate, etc., and the ketone type includes methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, γ-
Butyl lactone etc. In addition to these, polar solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, and N-methylpyrrolidone, ethyl lactate, methyl pyruvate, ethyl pyruvate, ethyl ethoxypropionate, and methylmethoxypropionate can be given. . These solvents can be used alone or as a mixture of two or more kinds. However, depending on the coating method, the desired coating film may not be satisfactorily formed. However, in this case, it can be easily detected by a simple coating test.

Further, the photosensitive composition of the present invention contains, in addition to the three components dissolved in the above-mentioned solvent, a surfactant, a modified resin and a plasticizer for the purpose of improving coating performance and coating properties. Etc. can also be added. Further, a dye or a coloring agent may be added for the purpose of improving visibility or for preventing standing waves. Further, in order to increase the sensitivity, it is possible to add a compound or a resin component that exhibits a sensitizing effect. These addition auxiliaries should be limited to such an amount that the effects of the present invention are not impaired.

The photosensitive composition thus obtained is used for forming a desired resist pattern. Although this composition is used in the form of a coating film, various methods such as a bar coater using various roll coater bars using a spinner roll of a spin coating method can be applied as means for forming a coating film. . However, since a glossy and flat coating film may not be obtained depending on the solvent used, it may be necessary to appropriately select a solvent suitable for coating depending on the coating method.

Substrates that can be used include silicon wafers on which various metal films are deposited, ITO, CR, M
It is a glass substrate or a ceramic substrate on which a metal such as o, Ta, Al, a nitride film, or a transparent conductive film is formed. Usually, these metal films or the like are formed to have a thickness of several hundred to several thousand angstroms depending on the purpose. The thickness after drying on these substrates is 0.5 to several μm by the above method.
m to form a coating film. This thickness is set to an appropriate value depending on the etching method or design dimensions.
Through the mask having a desired pattern on the substrate on which the resist film is formed, a stepper, a projection aligner or an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp,
A latent image is formed by an exposure device that has a light source such as an arc lamp or a xenon lamp. After the latent image is formed, development processing is performed with a predetermined developing solution, and the developing solution may be organic or inorganic. An example of the organic developer is an aqueous solution of tetramethylammonium hydroxide (abbreviated as TMAH) having a concentration of about 0.5 to 5% by weight. Inorganic developers contain ca. 0.1-5% caustic soda, caustic potash,
An aqueous solution of sodium silicate or the like can be given as an example. By exposing the exposed sample substrate to these developing solutions or contacting them for a predetermined time by a method such as shower or paddle, and then washing with water,
A desired resist pattern can be obtained.

Using the resist pattern thus obtained as a mask for etching, wet etching of the substrate is performed using an appropriate etchant (reagent for etching), or dry etching is performed using plasma or the like. After completion of the etching process, wet stripping using a stripping solution is performed or the resist is stripped and removed by dry ashing using plasma or the like. A desired circuit pattern is formed through such a series of processes.

[0025]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 A photosensitive composition solution (resist A) having the following composition was prepared. The formulation ratio is as follows: solid concentration 30%, photosensitive compound / (photosensitive compound + novolak) = 0.25.

Resist A component by weight: m / p cresol novolac resin 21.825 m / p ratio = 50/50, molecular weight = 12000 7.275 of 2,3,4-trihydroxybenzophenone Acid ester ・ ECA (ethylene glycol monoethyl ether acetate) 70.0 ・ 1-cyclohexyl-3- (2-morpholinoethyl) 0.90 -2-thiourea (abbreviated as CHMETU)

On the other hand, for comparison, a comparative resist solution (resist R1) having the same formulation ratio as the resist A and having a composition not containing the third component CHMETU was prepared. Resist R1 component weight part ・ m / p cresol novolac resin 22.5 m / p ratio = 50/50, molecular weight = 12000 ・ 7.5 1,2-naphthoquinonediazide-5-sulfonate of 2,3,4-trihydroxybenzophenone ・ECA 70.0

As a second comparative resist solution (resist R2), as an example of a thiourea compound _,
1'-Dimethylthiourea was selected and added in place of CHMETU to prepare a solution.

Resist R2 component by weight: m / p cresol novolac resin 21.825 m / p ratio = 50/50, molecular weight = 12000 * 7,275 of 2,3,4-trihydroxybenzophenone Acid ester ・ ECA ・ 1,1'-Dimethylurea (abbreviated as 1,1'-DMU) 0.90

First, a glass substrate on the surface of which an ITO film having a thickness of about 1200 Å was formed by a sputtering method was washed and dried by a predetermined method, and heat-treated for 15 minutes in a clean oven at 200 ° C for dehydration. It was After cooling, this substrate was used to apply the above resist solutions by a spin coater. For prebaking, an adsorption hot plate was used and heat treatment was performed at 110 ° C / 60 seconds. The thickness of the formed coating film of the photosensitive composition was 1.6 μm. Then, this ITO substrate is passed through a test reticle with a predetermined mask pattern, and a Canon mask aligner PL is used.
Ghi emitted from ultra high pressure mercury lamp using A-501F
-Proximity exposure by exposure to mixed UV light.
After that, a development process was performed by a dipping method at 23 ° C. for 60 seconds using a caustic soda aqueous solution adjusted to 0.75% as a developing solution.
After a predetermined time, DIW was performed for 30 seconds to wash with running water, and water drops were removed with an air knife to obtain a desired resist pattern.

The ITO substrate which had been treated up to this point was subjected to a post-baking treatment for 240 seconds on a heating plate kept at 120 ° C. using an adsorption type hot plate.

Subsequently, the post-baked substrate was wet-etched. The etchant used is 36% HCl: 35% FeCl ₂ : H ₂ O = 8: 1: 1
It was prepared in the ratio of (weight ratio). The etching was performed by a dipping method under the temperature condition of 40 ± 1 ° C. Prior to the etching test, the just etch time of the ITO substrate used was measured and found to be about 60 seconds. Therefore, the etching of the substrate with the resist pattern is performed by just etching time (60 seconds), 120 seconds, 180 seconds, 6 seconds.
The treatment was performed for four types of time of 00 seconds. This is because the over-etching time which is 2 to 3 times that of a normal production line and the excessive over-compulsion over-etching time are taken into consideration for just etching.

After the etching was completed, the dimensions of the resist pattern were measured, and then the resist was dissolved and removed with a 5% aqueous sodium hydroxide solution to obtain an ITO pattern. The dimensions of this ITO pattern were measured in the same manner as the resist pattern.
The transfer accuracy of the resist pattern to the ITO film was comparatively measured from the difference between the resist size and the ITO size.

As a result, when the pattern having a mask size of 20 μm was measured, the resist A had a side etching amount of about 2.3 μm in the forced 10-time etching. The amount was about 4.5 μm. The value of resist R2 is
It was 3.8 μm. Here, the one side etching amount is a value obtained by dividing the difference between the measured resist dimension and the ITO pattern dimension by two. The resist A had the smallest amount of side etching, and the transfer accuracy of the resist pattern to the ITO film was the best. Next, the resist R2 to which the 1,1'-thiourea compound having no cyclohexyl ring in the molecule was added was good. It was found that the resist R1 to which the urea compound was not added had a lower resist pattern transfer processing accuracy than other resists. Therefore, CHM added as the third component in resist A
The effect of improving the processing accuracy of ETU is clarified, and it is understood that the adhesion between the coating layer of the photosensitive composition and the substrate is significantly improved.

Examples 2 to 3 In the above Example 1, CHMETU was added based on the total amount of the alkali-soluble phenol resin and the o-quinonediazide compound.
The addition amount of 1% (referred to as resist B) and the same 5% (resist C) were used, and the solid content concentration was 30%.
%, And the ratio of photosensitive material / (photosensitive material + novolak) was 25%. Other than this, the same adjustment as in Example 1 was carried out.
These resists were processed up to etching in the same manner as in Example 1, and the processing accuracy was compared. As a result, the following values were obtained.

[0036] Considering together with the results of Example 1, it was clearly recognized that the processing accuracy became better as the amount of CHMETU of the present invention added increased.

Examples 4 to 5 The same experiment as in Example 1 (Resist D, Resist E) was conducted by replacing CHMETU used in Example 1 with 1,1'-cyclohexylurea (abbreviated as DCHU). However, for resist D, the amount of DCHU added was 1%, and for resist E, the amount added was 3% with respect to the total amount of the alkali-soluble resin and the photosensitive compound. DCHU compared to CHMETU, EC
Since the solubility in A is poor, the upper limit of the amount that can be added is about 6%. The test results are as shown below.
Even when DCHU was used, the amount of side etching was small and the adhesion was improved.

[0038] As described above, according to the present invention, the improvement of the adhesiveness in etching is extremely effective for the processing of a finer substrate.

[0039]

By using the photosensitive composition of the present invention,
Adhesion between the metal substrate and the coating layer of the photosensitive composition is improved, workability is improved, processing accuracy is improved, and precision photoetching that advances the miniaturization of circuit patterns is possible. To do. Further, the improvement of processing accuracy also contributes to the improvement of yield. The throughput can be expected to be improved by improving the etching process, including the use of a stronger etchant.

Claims (2)

[Claims] 1. (a) Alkali-soluble phenolic resin (b) o-quinonediazide compound (c) Solvent capable of sufficiently dissolving (a), (b) and the following (d) (d) The following general formula A positive photosensitive composition comprising at least a compound represented by formula (I). Embedded image In formula (I), X represents a sulfur atom or an oxygen atom,
At least one of R ₁ , R ₂ , R ₃ and R ₄ is
It represents an alkyl group having a cyclohexyl ring, a morpholine ring, or a cyclohexyl ring or a morpholine ring, and the remaining ones each represent a hydrogen atom, an alkyl group or an aryl group. 2. The addition amount of the compound represented by the general formula (I) is the alkali-soluble phenol resin and the o-
The positive photosensitive composition according to claim 1, wherein the content of the quinonediazide compound is 0.01% by weight to 15% by weight based on the total amount.