JP4446181B2 - Pattern formation method - Google Patents

Description

  The present invention relates to a pattern forming method. More specifically, the present invention relates to a method for forming a resist pattern having a halftone pattern portion using a photosensitive resist composition, for example, a liquid crystal display, organic electroluminescence (hereinafter, electroluminescence is abbreviated as EL). .) It relates to a pattern forming method applied in the field of flat display devices such as displays.

In recent years, flat display devices such as liquid crystal display devices and organic EL elements have attracted attention as electronic display devices.
Since the liquid crystal display device is smaller and more compact than a CRT (cathode ray tube) display device, various devices including the liquid crystal display device have been widely used. For example, there is a great market need for downsizing various devices including consumer devices such as personal computers and video cameras. Specifically, there are a wide range of downsized portable devices called laptop computers or cameras with LCD monitors. It has become popular. In these devices, it is indispensable to have a liquid crystal display device, and there is a strong demand for high performance and high performance such as color display and high brightness. Since this liquid crystal display device is not a self-luminous type, a light source such as a backlight or a front light is required.
On the other hand, EL elements using electroluminescence are self-luminous and have high visibility, are completely solid elements, and have excellent impact resistance. Therefore, as EL elements in various display devices, Is being used.
This EL element includes an inorganic EL element using an inorganic compound as a light emitting material and an organic EL element using an organic compound. Among these, the organic EL element can greatly reduce the applied voltage, is easy to downsize, consumes low power, can emit surface light, and can easily emit three primary colors. As a light emitting device, practical research has been actively conducted.

In these display devices, there are various driving methods, but an active matrix method using TFT elements is often adopted.
FIG. 1 is a cross-sectional view showing a configuration of an example of a TFT array substrate used in an active matrix liquid crystal display device using TFT elements.
A gate electrode 2 made of Mo / Al / Nd or the like is provided on the transparent insulating substrate 1, and an active layer (amorphous silicon or polysilicon) is formed thereon via a gate insulating film 3 made of SiNx or the like. A semiconductor switch layer 4) is provided. An S / D layer (a wiring layer for applying a voltage to a pixel electrode made of Mo or the like) 5 is provided in contact with the active layer 4, and a PAS layer (an insulating layer made of SiN _x or the like) 6 is formed thereon. Is provided.
A hole 8 is formed in the PAS layer 6, and a pixel layer (pixel electrode layer for controlling liquid crystal molecules) that is electrically connected to the S / D layer 5 by sputtering ITO (tin-doped indium oxide) thereon. ) 7 is provided.

Conventionally, such a TFT array substrate has been manufactured by repeating fine patterning by a photolithography process using five or more photomasks. However, in recent years, from the viewpoint of improving the productivity and manufacturing yield of flat display devices such as liquid crystal display devices and reducing costs, studies have been made on reducing the number of photomasks used, that is, reducing the photolithography process. A four-mask process has been studied (see, for example, Patent Document 1 and Patent Document 2).
As the four-mask process, for example, a resist film formed by applying a photosensitive resist composition containing a resin and a photosensitive component to a substrate, a mask having a semi-transmissive film portion, and the resolution limit of an exposure apparatus or less. A resist pattern is formed on the substrate by performing exposure using a halftone mask such as a mask having a slit or mesh portion having a size and development processing, and then performing wet etching (or dry etching) and dry etching. Examples include a process including a step of sequentially performing etching, wet etching (or dry etching), and a resist pattern peeling process.
In such a 4-mask process, an exposure margin (hereinafter referred to as a residual film thickness exposure margin) relating to a film thickness of a resist pattern (hereinafter referred to as a halftone pattern) corresponding to a halftone portion of the mask is wide, that is, exposure. It is desirable that the variation of the remaining film thickness (residual film rate) with respect to the variation in amount is small. If the variation in the remaining film ratio of the halftone pattern portion is large, the variation in the line width at the central opening after the dry etching process becomes large. In severe cases, the central part may not open even after the dry etching process. Arise. This variation in the line width of the central opening portion leads to variations in TFT element characteristics, which affects the product yield (productivity).

Furthermore, it is desirable that the resist pattern has excellent dry etching resistance. In the four-mask process, there is a step of processing an amorphous silicon layer or a polysilicon layer by dry etching. At this time, if the resistance to dry etching of the resist is low, the film thickness of the resist pattern is reduced by dry etching. In this wet etching process, the designed line width cannot be obtained.
A resist using a general novolac resin has insufficient dry etching resistance. Therefore, a method for improving the dry etching resistance by adding a step of crosslinking the resist is disclosed (for example, see Patent Document 3). However, this method is a method in which the number of steps is increased, resulting in a decrease in productivity.
JP 2002-25894 A JP 2002-151381 A Japanese Patent Application Laid-Open No. 2004-177683

  Under such circumstances, the present invention provides a method of forming a resist pattern having a halftone pattern portion having a wide residual film thickness exposure margin and high dry etching resistance using a photosensitive resist composition. It was made for the purpose of doing.

As a result of extensive research on a method for forming a resist pattern having a halftone pattern portion, the present inventors have further added a phenol compound having a specific structure to a photosensitive resist composition containing an alkali-soluble resin and a quinonediazide group-containing compound. It has been found that the purpose can be achieved by the inclusion, and the present invention has been completed based on this finding.
That is, the present invention
(1) A resist film is formed by applying a photosensitive resist composition containing (a) (A) an alkali-soluble resin, (B) a quinonediazide group-containing compound, (C) a solvent, and (D) a phenol compound to a substrate. Process,
(B) exposing the resist film through a mask having a halftone portion;
(C) a step of developing the exposed resist film by bringing a developer into contact therewith,
In a resist pattern forming method including:
The (D) phenol compound is a condensate of phenols and α, α′-2 substituted xylenes,
(2) The phenol is represented by the general formula (I)

(In formula, R < ¹ > -R < ³ > shows a hydrogen atom or a C1-C4 alkyl group each independently.)
In which α, α′-2 substituted xylenes are represented by the general formula (II)

(Wherein R ^{4 to} R ¹¹ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X ¹ and X ² each independently represent a hydroxyl group, a toluenesulfonyloxy group, a methanesulfonyloxy group, or An alkoxy group having 1 to 4 carbon atoms is shown.)
The pattern forming method according to item (1), which is a compound represented by the formula:
(3) The pattern forming method as described in (1) or (2) above, wherein the solvent (C) is mainly composed of propylene glycol monomethyl ether acetate, and (4) a group used in the step (a). The pattern forming method according to any one of (1) to (3), wherein the material is a substrate for manufacturing a TFT array,
Is to provide.

  According to the present invention, it is possible to provide a method for forming a resist pattern having a halftone pattern portion having a wide residual film thickness exposure margin and high dry etching resistance using a photosensitive resist composition.

The pattern forming method of the present invention includes (a) a step of applying a photosensitive resist composition to a substrate, (b) a step of exposing through a halftone mask, and (c) a developing step.
First, the photosensitive resist composition used in the step (a) will be described.
As the photosensitive resist composition, a composition containing (A) an alkali-soluble resin, (B) a quinonediazide group-containing compound, (C) a solvent, and (D) a phenol compound having a specific structure is used.
The alkali-soluble resin as component (A) is not particularly limited, and any one of alkali-soluble resins conventionally used in photoresists using quinonediazide sulfonate as a photosensitizer can be appropriately selected. Can be used. Specific examples of the alkali-soluble resin include a condensation reaction product (novolak type resin) of phenols with aldehydes or ketones, vinylphenol polymers, isopropenylphenol polymers, and hydrogenation of these phenol resins. A reaction product etc. can be mentioned. The condensation reaction product can be obtained by a conventional method, for example, by reacting phenols with aldehydes or ketones in the presence of an acidic catalyst.

  Among the above resins, examples of phenols used as raw materials in the condensation reaction product of phenols and aldehydes or ketones include phenol, o-cresol, m-cresol, p-cresol, and 2,3. -Xylenol, 2,4-xylenol, 3,5-xylenol, 2,6-xylenol, 1,2,3-trimethylphenol, 2,3,4-trimethylphenol, 2,3,5-trimethylphenol, o- Ethylphenol, m-ethylphenol, p-ethylphenol, o-propylphenol, m-propylphenol, p-propylphenol, o-butylphenol, m-butylphenol, p-butylphenol, o-phenylphenol, m-phenylphenol, p-phenylphenol, o-methoxyphenol, m -Monovalent phenols such as methoxyphenol, p-methoxyphenol, 3-methylmethoxyphenol; polyhydric phenols such as resorcinol, pyrocatechol, hydroquinone, bisphenol A, phloroglucinol, pyrogallol and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of aldehydes include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropionaldehyde, β-phenylpropionaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-Butylbenzaldehyde, terephthalaldehyde, etc. Examples of ketones that can be used include acetone, methyl ethyl ketone, diethyl ketone, diphenyl ketone, and acetophene. These aldehydes and ketones may be used individually by 1 type, and may be used in combination of 2 or more type.

On the other hand, the vinylphenol polymer and the isopropenylphenol polymer are selected from a homopolymer of vinylphenol and isopropenylphenol and a copolymer of a component copolymerizable with vinylphenol and isopropenylphenol. . Specific examples of the copolymerizable component include acrylic acid, methacrylic acid, styrene, maleic anhydride, maleic imide, vinyl acetate, acrylonitrile, and derivatives thereof. The copolymer can be obtained by a known method.
Furthermore, the hydrogenation reaction product of the phenol resin can be obtained by any known method, for example, by dissolving the above phenol resin in an organic solvent and performing hydrogenation in the presence of a homogeneous or heterogeneous catalyst. It can be done.
These alkali-soluble resins can also be used as those whose molecular weight and molecular weight distribution are controlled by known means. As a method for controlling the molecular weight and molecular weight distribution, the resin is crushed and subjected to solid-liquid extraction with an organic solvent having an appropriate solubility, or the resin is dissolved in a good solvent and dropped into the poor solvent, or the poor solvent And a method such as solid-liquid or liquid-liquid extraction is added.

As the alkali-soluble resin of component (A), one kind may be used alone, or two or more kinds may be used in combination. In the present invention, among the alkali-soluble resins, a phenol-based novolak resin obtained by polycondensation of phenols and aldehydes in the presence of an acid catalyst is particularly preferable. Moreover, as phenols used for these novolak-type resins, mixed cresol of m-cresol and p-cresol is preferable.
In the photosensitive resist composition, the quinonediazide group-containing compound used as the component (B) is not particularly limited, and a known photosensitive agent conventionally used in quinonediazide-phenol novolac resists can be used. The quinonediazide group-containing compound is generally obtained by reacting an acid halide such as naphthoquinonediazidesulfonic acid chloride or benzoquinonediazidesulfonic acid chloride with a low molecular compound or a high molecular compound having a functional group capable of performing a condensation reaction therewith. Compounds are preferred. Here, examples of the functional group capable of condensing with an acid halide include a hydroxyl group and an amino group, and a hydroxyl group is preferred.

Examples of the compound containing a hydroxyl group that can be condensed with an acid halide (hereinafter referred to as polyphenols) include 2,3,4-trihydroxybenzophenone, 2,4,4′-trihydroxybenzophenone, 2,3,4, Polyhydroxybenzophenones such as 4′-tetrahydroxybenzophenone, 2,4,2 ′, 4′-tetrahydroxybenzophenone, 2,3,4,2 ′, 4′-pentahydroxybenzophenone; methyl gallate, ethyl gallate Gallic esters such as propyl gallate; polyhydroxybisphenylalkanes such as 2,2-bis (4-hydroxyphenyl) propane and 2,2-bis (2,4-dihydroxyphenyl) propane; -Hydroxyphenyl) methane, 1,1,1-tris (4-hydroxy-3-methylphenyl) ethane, 1,1,1-tris (4-hydroxy Loxy-3-methylphenyl) ethane, 1,1,1-tris (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxy-3-methylphenyl) -1- (4-hydroxyphenyl) ethane, Polyhydroxytrisphenylalkanes such as bis (4-hydroxy-3-methylphenyl) -2-hydroxy-4-methoxyphenylmethane; 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 1,1 , 2,2-tetrakis (3-methyl-4-hydroxyphenyl) ethane, 1,1,3,3-tetrakis (4-hydroxyphenyl) propane and other polyhydroxytetrakisphenylalkanes; α, α, α ′, α′-tetrakis (4-hydroxyphenyl) -3-xylene, α, α, α ′, α′-tetrakis (4-hydroxyphenyl) -4-xylene, α, α, α ′, α′-tetrakis (3 -Methyl- Polyhydroxytetrakisphenylxylenes such as 4-hydroxyphenyl) -3-xylene; 2,6-bis (2,4-dihydroxybenzyl) -p-cresol, 2,6-bis (2,4-dihydroxy-3- Methylbenzyl) -p-cresol, 4,6-bis (4-hydroxybenzyl) resorcin, 4,6-bis (4-hydroxy-3-methylbenzyl) resorcin, 4,6-bis (4-hydroxybenzyl)- Examples include 2-methylresorcin, trimers of phenols and formalin such as 4,6-bis (4-hydroxy-3-methylbenzyl) -2-methylresorcin, tetramers of phenols and formalin, and novolak resins. . These can be used alone or in combination of two or more.
In particular, quinonediazide sulfonic acid esters obtained by using tri- or tetrahydroxybenzophenones as polyphenols are preferable because they give good sensitivity and resolution.

Examples of the acid halide include 1,2-naphthoquinone diazide-5-sulfonyl chloride, 1,2-naphthoquinone diazide-4-sulfonyl chloride, and the like.
The method for producing the ester compound obtained from these quinonediazidesulfonic acid halides and the above polyphenols is not particularly limited, but quinonediazidesulfonic acid halide (preferably naphthoquinonediazidesulfonic acid chloride) is used in a solvent such as acetone, dioxane, tetrahydrofuran or the like according to a conventional method. Among them, inorganic bases such as sodium carbonate, sodium bicarbonate, sodium hydroxide and potassium hydroxide, or trimethylamine, triethylamine, tripropylamine, diisopropylamine, tributylamine, pyrrolidine, piperidine, piperazine, morpholine, pyridine, dicyclohexylamine It can obtain by making it react with polyphenols in presence of organic bases, such as.
When the quinonediazide group-containing compound used in the present invention is an ester compound, the ratio of the hydroxyl group of these polyphenols to the quinonediazide sulfonate ester group (average esterification rate) is the ratio of the hydroxyl groups of the polyphenols used in the reaction. It is a value calculated from the number of equivalents and the number of moles of quinonediazide sulfonic acid halide, usually 60% or more, preferably 65% or more, and the upper limit is usually 100%, preferably 90%. If this average esterification rate is 60% or more, the pattern shape and resolution can be improved.
In the present invention, a 1,2-naphthoquinonediazide-5-sulfonyl compound and / or a 1,2-naphthoquinonediazide-4-sulfonyl compound are suitable as the quinonediazide group-containing compound as the component (B).
The content of the quinonediazide group-containing compound as the component (B) is usually in the range of 5 to 50 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the alkali-soluble resin of the component (A). If content of (B) component is in the said range, the photosensitive resist composition which is excellent in the balance of resist characteristics, such as an effective sensitivity, a residual film rate, and resolution, will be obtained.

  In the photosensitive resist composition, as the solvent for the component (C), conventionally known solvents can be used as the solvent for the photosensitive resist composition. For example, linear ketones such as acetone, methyl ethyl ketone, cyclopentanone, 2-hexanone, 3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, 4-octanone; n- Alcohols such as propyl alcohol, isopropyl alcohol, n-butyl alcohol and cyclohexanol; ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and dioxane; alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; formic acid Esters such as propyl, butyl formate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl lactate, ethyl lactate Cellosolve esters such as cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propyl cellosolve acetate, butyl cellosolve acetate; propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether, etc. Propylene glycols; Diethylene glycols such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether; γ-butyrolactone, γ-valerolactone, γ-cap Saturated γ-lactones such as lactone and γ-caprolactone; Halogenated hydrocarbons such as trichloroethylene; Aromatic hydrocarbons such as toluene and xylene; Polar solvents such as dimethylacetamide, dimethylformamide, and N-methylacetamide Is mentioned. These solvents may be used singly or in combination of two or more. In particular, propylene glycol monomethyl ether acetate is used alone, or a combination of other solvents with this as a main component is suitable. Moreover, the usage-amount of a solvent should just be sufficient quantity to melt | dissolve or disperse | distribute each said component uniformly.

The phenol compound of component (D) used in the photosensitive resist composition is a condensate of phenols and α, α′-2-substituted xylenes.
The phenols are benzene having one phenolic hydroxyl group, and preferred examples include those represented by the general formula (I)

(In formula, R < ¹ > -R < ³ > shows a hydrogen atom or a C1-C4 alkyl group each independently.)
The compound represented by these is mentioned.
In the general formula (I), the alkyl group having 1 to 4 carbon atoms of R ^{1 to} R ³ includes methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec -Butyl group and tert-butyl group can be mentioned. R ^{1 to} R ³ may be the same or different.
Specific examples of the phenols represented by the general formula (I) include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, and 3,4- Dimethylphenol, 3,5 dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-t-butylphenol, 3-t -Butylphenol, 4-t-butylphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-t-butyl-5-methylphenol, etc. Can be mentioned. These compounds can be used alone or in combination of two or more.

  On the other hand, the α, α′-2-substituted xylenes are represented by the general formula (II)

(Wherein R ^{4 to} R ¹¹ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X ¹ and X ² each independently represent a hydroxyl group, a toluenesulfonyloxy group, a methanesulfonyloxy group, or An alkoxy group having 1 to 4 carbon atoms is shown.)
The compound represented by these is mentioned.
In the general formula (II), the alkyl group having 1 to 4 carbon atoms of R ^{4 to} R ¹¹ is the same as that exemplified in the description of R ^{1 to} R ³ of the general formula (I). be able to. R ^{4 to} R ¹¹ may be the same or different. X ¹ and X ² may be the same or different.
Preferable specific examples of the α, α′-2 substituted xylenes represented by the general formula (II) include o-xylylene glycol, m-xylylene glycol, p-xylylene glycol, and o-xylylene glycol diester. Toluenesulfonate, m-xylylene glycol ditoluenesulfonate, p-xylylene glycol ditoluenesulfonate, o-xylylene glycol dimesylate, m-xylylene glycol dimesylate, p-xylylene glycol dimesylate 2,3,5,6-tetramethyl-p-xylylene glycol, 2,5-dimethyl-p-xylylene glycol, p-xylylene glycol dimethyl ether, p-xylylene glycol diethyl ether, o-xylylene glycol Dimethyl ether, o-xylylene glycol diethyl ether Le, m- xylylene glycol dimethyl ether, m- etc. xylylene glycol diethyl ether. These compounds may be used alone or in combination of two or more.

Examples of the catalyst include stannic chloride, zinc chloride, ferric chloride, cupric chloride, cupric sulfate, mercuric sulfate, mercuric sulfate, mercuric chloride, mercuric chloride, Inorganic compounds such as silver sulfate, silver chloride, sodium hydrogen sulfate and sulfuric acid; organic sulfonic acids such as monoethyl sulfuric acid, diethyl sulfuric acid, dimethyl sulfuric acid, p-toluenesulfonic acid, p-phenolsulfonic acid and methanesulfonic acid; . These may be used singly or in combination of two or more. Among these, stannic chloride, diethyl sulfate, and p-phenolsulfonic acid are preferable.
Although there is no restriction | limiting in particular in the usage-amount of a catalyst, It is about 0.001 to 5 weight% normally with respect to all the raw materials, Preferably it is 0.01 to 0.5 weight%.
The use ratio of phenols to α, α′-2-substituted xylenes is preferably 1.3 or more in terms of molar ratio.
The reaction can be carried out without solvent or in the presence of a solvent. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, acetates such as ethyl acetate and butyl acetate, and aromatic hydrocarbons such as benzene, toluene, and xylene. The reaction temperature is usually about 120 to 200 ° C., preferably 130 to 160 ° C., and the reaction time is about 0.5 to 10 hours.

In the present invention, the polystyrene-equivalent weight average molecular weight of the (D) phenol compound is usually 2000 or less, preferably 1500 or less. Moreover, the part exceeding the weight average molecular weight 2000 in a gel permeation chromatography (GPC) pattern is 30% or less normally, Preferably it is 20% or less.
This (D) phenol compound can also be used as a compound whose molecular weight and molecular weight distribution are controlled by known means. As a method for controlling the molecular weight and molecular weight distribution, the compound is crushed and subjected to solid-liquid extraction with an organic solvent having an appropriate solubility, or the compound is dissolved in a good solvent and dropped into the poor solvent, or Examples of the method include dropping a poor solvent and performing solid-liquid or liquid-liquid extraction.
The content of the phenol compound of the component (D) in the photosensitive resist composition is usually 3 to 100 parts by weight with respect to 100 parts by weight of the alkali-soluble resin of the component (A). If the content of this phenol compound is in the above range, a resist pattern having a halftone pattern portion having a wide residual film thickness exposure margin and high dry etching resistance can be formed. The preferred content is 5 to 60 parts by weight, and more preferably 10 to 40 parts by weight.

In the photosensitive resist composition, for the purpose of increasing sensitivity, the polyhydroxybenzophenones; monophenols such as p-phenylphenol and p-isopropylphenol; biphenol, 4,4′-dihydroxydiphenyl ether, 4, 4'-dihydroxybenzophenone, bisphenol A (made by Honshu Chemical Industry), bisphenol C (made by Honshu Chemical Industry), bisphenol E (made by Honshu Chemical Industry), bisphenol F (made by Honshu Chemical Industry), bisphenol AP (Honshu) Chemical Industry), bisphenol M (Mitsui Chemicals), bisphenol P (Mitsui Chemicals), bisphenol Z (Honshu Chemical), 1,1-bis (4-hydroxyphenyl) cyclopentane, 9,9-bis (4-hydroxyphenyl) fluorene, 1,1-bis (5-methyl-2-hydroxy) Bisphenols such as droxyphenyl) methane, 3,5-dimethyl-4-hydroxybenzylphenol; 1,1,1-tris (4-hydroxyphenyl) methane, 1,1,1-tris (4-hydroxyphenyl) Ethane, 1,1-bis (3-methyl-4-hydroxyphenyl) -1- (4-hydroxyphenyl) methane, 1,1-bis (2,5-dimethyl-4-hydroxyphenyl) -1- (2 -Hydroxyphenyl) methane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) -1- (2-hydroxyphenyl) methane, 2,6-bis (5-methyl-2-hydroxybenzyl)- 4-methylphenol, 2,6-bis (4-hydroxybenzyl) -4-methylphenol, 2,6-bis (3-methyl-4-hydroxybenzyl) -4-methylphenol, 2,6-bis (3 , 5-Di Trisphenols such as til-4-hydroxybenzyl) -4-methylphenol, trisphenol-PA (Honshu Chemical Industry Co., Ltd.), and trisphenol-TC (Honshu Chemical Industry Co., Ltd.); 1,1,2,2- Tetrakis (4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-methyl-4-hydroxyphenyl) ethane, 1,1,3,3- (4-hydroxyphenyl) propane, 1,1, 5,5-tetrakis (4-hydroxyphenyl) pentane, α, α, α ′, α′-tetrakis (4-hydroxyphenyl) -3-xylene, α, α, α ′, α′-tetrakis (4-hydroxy Phenyl) -4-xylene, α, α, α ′, α′-tetrakis (3-methyl-4-hydroxyphenyl) -3-xylene, α, α, α ′, α′-tetrakis (3-methyl-4 -Hydroxyphenyl) -4-xylene and other tetrakisphenols Etc. may be contained. Of these, trisphenols and polyhydroxybenzophenones are particularly preferred.
If necessary, the photosensitive resist composition further includes compatible additives, for example, conventional resins such as additional resins, plasticizers, stabilizers, and surfactants for improving the performance of the resist film. Can be added.

Next, the pattern forming method of the present invention will be described. First, in the step (a), the above-described photosensitive resist composition is applied to a substrate.
Specifically, the photosensitive resist composition is applied to the surface of a substrate such as a silicon wafer, a glass substrate, other insulating substrates; an inner layer substrate; a support such as a resin film or a metal foil; It is applied by various methods such as a method and a spin coating method. Next, this coating film is pre-baked to obtain a resist film having no fluidity. The prebaking is usually performed by heat treatment at 60 to 120 ° C. for about 10 to 600 seconds.
As a base material used in the step (a), a substrate for manufacturing a TFT array is suitable.
Next, in the step (b), the resist film obtained in the step (a) is irradiated with actinic rays through a mask having a halftone portion to perform exposure. Examples of the actinic rays include ultraviolet rays, deep-UV, and excimer laser light. Among these, ultraviolet rays are preferable.
Further, in step (c), the latent image pattern is exposed (developed) by bringing the resist film having the latent image pattern on the substrate into contact with the developer, thereby forming a resist pattern. In addition, before development, heating (PEB treatment: Post Exposure Bake) can be performed as necessary. By performing the PEB treatment, it is possible to reduce development residues such as unnecessary resist components which are dissolved in the developer and should be removed.
Here, the “mask having a halftone portion” is a photomask having a total light-shielding region, a total transmission region, and a semi-light-shielding region, and specifically, formed of a material having a relatively low light transmittance. These include a mask having a semi-transmissive film portion and a mask having a slit or mesh portion having a size less than the resolution limit of the exposure apparatus. By using such a mask, it is possible to partially limit the light beam applied to the resist film, and thereby, in the resist pattern obtained in the next step (c), the entire light shielding region and the total exposure region. It is possible to form a resist pattern (that is, a halftone pattern) portion having a different film thickness from the resist pattern corresponding to.

As the developer, an alkaline aqueous solution is usually used. Examples of the alkali compound contained in the aqueous alkali solution include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine. Amines; secondary amines such as diethylamine and di-n-propylamine; tertiary amines such as triethylamine, methyldiethylamine and N-methylpyrrolidone; alcohol amines such as dimethylethanolamine and triethanolamine; tetra Quaternary ammonium salts such as methylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, choline; pyrrole, piperidine, 1,8-diazabicyclo [5.4.0] undec-7 -Cyclic amines such as -ene and 1,5-diazabicyclo [4.3.0] non-5-ene; One kind of these alkali compounds may be contained in the alkaline aqueous solution, or two or more kinds thereof may be contained.
A developer prepared by adding an appropriate amount of a water-soluble organic solvent such as methanol or ethanol or a surfactant to an alkaline aqueous solution can also be used. The development time is usually 30 to 180 seconds. The contact method between the developer and the resist film having the latent image pattern may be a paddle method, a spray method, a dipping method, or the like. The development temperature is usually 15 to 35 ° C, preferably 20 to 30 ° C.

After forming the target halftone pattern area on the base material in this way, the base material is removed in order to remove unnecessary development residues remaining on the base material, the back surface, and the edge portion as necessary. And the rinse liquid can be contacted by a conventional method. The base material brought into contact with the rinse liquid is usually dried with compressed air or compressed nitrogen to remove the rinse liquid on the base material. Furthermore, if necessary, the entire surface of the substrate with the resist pattern can be irradiated with actinic rays.
The resist pattern thus formed on the substrate can be post-baked at an appropriate temperature as necessary. There is no particular limitation on the post-baking method, and an oven or a hot plate is generally used, and it is preferable to use a hot plate in view of uniformity of processing temperature.
Such a pattern forming method of the present invention can form a resist pattern having a wide residual film thickness exposure margin in a halftone pattern portion and having high dry etching resistance, and is used for a liquid crystal display or an organic EL display. The present invention can be applied to a four-mask process in manufacturing a TFT array substrate.

FIG. 2 is a schematic diagram illustrating an example of a manufacturing process using a four-mask process for a TFT array substrate.
First, a gate metal layer 22 made of Mo / Al / Nd, an insulating film 23 made of SiN _x , an active layer 24 made of amorphous silicon, polysilicon, or the like on a transparent insulating substrate 21. And a TFT array substrate working member in which the S / D layer 25 composed of Mo or the like is sequentially provided.
After forming a resist film 26 on the S / D layer 25 of this member using the photosensitive resist composition according to the present invention, the resist film is irradiated with an actinic ray such as ultraviolet rays through a halftone mask 27. Then, exposure is performed (step (a)).
Next, the resist pattern 26 'is formed by developing with an alkaline aqueous solution ((B)). Reference numeral 28 denotes a halftone pattern portion. Next, using the resist pattern 26 ′ as a mask, the S / D layer 25 is wet-etched to 25 ′ (step (c)), and further dry-etched, so that the halftone pattern 26 ′ becomes 26 ″ and the active layer 24 Is 24 ′ [(D) step].
Next, in the S / D layer 25 ′, only the region corresponding to the channel region is wet-etched to set 25 ′ to 25 ″ [(e) step]. Finally, the remaining resist pattern 26 ″ is stripped [step (f)].
The wet etching method and the dry etching method are not particularly limited, and a known method conventionally used for manufacturing a TFT array substrate can be used.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Production Example 1 Production of Phenol Compound (d-1) 188.2 g (2 mol) of phenol, 6.6 g of methanol and 0.41 g of diethyl sulfuric acid were charged into a reactor having a condenser through which cooling water was passed at 70 ° C. While stirring, the liquid temperature was raised to 140 ° C. with an oil bath. When the liquid temperature reached 140 ° C., p-xylylene glycol dimethyl ether (PXDM) was continuously added over 2 hours, and then an aging reaction was performed at the liquid temperature of 140 ° C. for 90 minutes.
Next, the liquid temperature was raised to 160 ° C., and unreacted phenol was removed under reduced pressure to obtain 305 g of a resin having a softening point of 92 ° C.
The obtained resin was dissolved in 2700 g of toluene to obtain a homogeneous solution, and 3000 g of water was added with stirring. After stirring for 1 hour and allowing to stand, two layers were separated. The lower aqueous layer was extracted, and toluene was distilled off from the upper toluene layer at room temperature under reduced pressure. The toluene was gradually heated, and finally residual toluene was thoroughly distilled off at 170 ° C. The reaction product was discharged in a heated state and allowed to cool to obtain 285 g of resin.
Production Example 2 Production of Phenol Compound (d-2) 108-1.4 g (10 mol) of o-cresol, 32.4 g of methanol and 2.2 g of diethyl sulfuric acid were added to a reactor having a condenser through which 70 ° C. cooling water was passed. While charging and stirring, the liquid temperature was raised to 150 ° C. with an oil bath. When the liquid temperature reached 150 ° C., PXDM was continuously added over 4 hours, and then an aging reaction was performed at the liquid temperature of 150 ° C. for 3 hours.
Next, the liquid temperature was raised to 170 ° C., and unreacted o-cresol was removed under reduced pressure to obtain 1610 g of a resin having a softening point of 82 ° C.
The obtained resin was dissolved in 15 kg of toluene to obtain a homogeneous solution, and 15 kg of water was added with stirring. After stirring for 1 hour and allowing to stand, two layers were separated. The lower aqueous layer was extracted, and toluene was distilled off from the upper toluene layer at room temperature under reduced pressure. The toluene was gradually heated, and finally residual toluene was thoroughly distilled off at 170 ° C. The reaction product was discharged in a heated state and allowed to cool to obtain 1440 g of resin.

Production Example 3 Production of Novolac Type Resin (a-1) In a flask equipped with a cooling tube and a stirrer, 108.1 g of m-cresol, 54.0 g of p-cresol, 82.7 g of 37 wt% formalin, and dioxalic acid Hydrate 5.0 was charged and reacted for 2 hours while maintaining the temperature at 95-100 ° C. Thereafter, water was distilled off at 100 to 105 ° C. over 2 hours, and the pressure was reduced to about 0.1 kPa while raising the temperature to 180 ° C. After removing unreacted monomers and water, the molten resin was returned to room temperature. And 145 g of novolac resin (a-1) was obtained.
Production Example 4 Production of Photosensitizer (b-1) 2,3,4,4′-Tetrahydroxybenzophenone was used as a polyhydroxy compound, and a 1,2-naphthoquinonediazide having a molar ratio corresponding to 75% of this OH group. -5-sulfonic acid chloride was dissolved in dioxane to make a 10 wt% solution. While controlling the temperature at 20 to 25 ° C., 1.2 equivalents of triethylamine of 1,2-naphthoquinonediazide-5-sulfonic acid chloride was added dropwise over 30 minutes, and the reaction was further completed by maintaining for 2 hours. . The precipitated solid content was filtered, washed with ion exchange water, and dried to obtain a photosensitizer (b-1).
Production Example 5 Production of Photosensitizer (b-2) Using 2,3,4-trihydroxybenzophenone as a polyhydroxy compound, the charged molar ratio of 1,2-naphthoquinonediazide-5-sulfonic acid chloride to this OH group is A photosensitizer (b-2) was obtained by the same formulation as in Production Example 4 except that the amount was 67%.

Example 1
After dissolving 50 g of novolak type resin (a-1), 12 g of photosensitizer (b-1) and 10 g of phenol compound (d-1) in 195 g of propylene glycol monomethyl ether acetate (PGMEA), this solution was prepared with a pore size of 0.5. The mixture was filtered through a 1 μm polytetrafluoroethylene filter to prepare a photosensitive resist composition (resist solution).
The resist solution was applied onto a silicon wafer with a spin coater and then pre-baked for 150 seconds with a 110 ° C. hot plate to form a resist film having a thickness of 2.0 μm.
The silicon wafer on which the resist film was formed was exposed through a halftone mask shown in FIG. 3 using a mirror projection mask aligner product name “MPA-600FA” (manufactured by Canon Inc.). By performing the same operation while changing the exposure amount, a plurality of wafers having different exposure amounts were obtained. Each exposed wafer was developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution by a paddle method at 23 ° C. for 80 seconds to form a halftone pattern shown in the sectional view of FIG. 4 on each wafer.
The following evaluation was performed on this pattern forming method.
(1) Remaining film thickness exposure margin evaluation For each wafer on which a halftone pattern is formed, the film thickness is observed with a scanning electron microscope (SEM), thereby obtaining the relationship between the exposure amount and the remaining film thickness of the halftone portion. It was. FIG. 5 is a graph showing the relationship between the exposure amount (horizontal axis) and the remaining film thickness (vertical axis) of the halftone pattern portion.
The amount of change in the remaining film thickness when the exposure amount changes ± 10% around the exposure amount at which the remaining film thickness becomes 0.4 μm was used as an index of the remaining film thickness exposure margin of the halftone pattern portion. A resist with a smaller change in the remaining film thickness is preferable because the exposure margin is wider. In the case of the photosensitive resist composition of this example, the amount of change in the remaining film thickness of the halftone pattern portion was 0.36 μm.

(2) Evaluation of dry etching resistance The resist solution was applied onto a silicon wafer by a spin coater and then pre-baked on a hot plate at 110 ° C. for 150 seconds to form a resist film having a thickness of 2.0 μm.
The silicon wafer on which the resist film is formed is subjected to gas species SF ₆ : 50 cm ³ / min (standard state) + O ₂ : 25 cm ³ / min (standard state), pressure using a parallel plate type RIE (Reactive Ion Etching) apparatus. Dry etching was performed under the conditions of 133 Pa, power of 100 W, and time of 180 seconds.
The resist film thickness after the treatment was measured, and the dry etching film reduction rate per minute was calculated. In the case of the resist composition of this example, the dry etching film reduction rate per minute was 264 nm / min.
Examples 2 and 3 and Comparative Examples 1 and 2
A photosensitive resist composition was prepared in the same manner as in Example 1 using the type of novolak type resin, photosensitive agent and phenol compound shown in Table 1, and a pattern was formed for evaluation. The results are shown in Table 1.

  By forming a resist pattern having a halftone pattern portion by the method of the present invention, a flat display device such as a liquid crystal display or an organic EL display can be manufactured with a high yield.

It is sectional drawing which shows the structure of one example of the TFT array substrate used for the active matrix type liquid crystal display device using a TFT element. It is a manufacturing-process schematic of an example by 4 mask processes of a TFT array substrate. It is a top view of the halftone mask pattern used by the Example and the comparative example. It is sectional drawing of the resist pattern obtained by the Example and the comparative example. It is a graph which shows one example of the relationship between exposure amount and the remaining film thickness of a halftone pattern part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent insulating substrate 2 Gate electrode 3 Gate electrode insulating film 4 Active layer 5 S / D layer 6 PAS layer 7 Pixel layer 8 Hole 21 Transparent insulating substrate 22 Gate metal layer 23 Insulating film 24, 24 'Active layer 25, 25 ', 25 "S / D layer 26, 26', 26" resist layer 27 halftone mask 28 residual film of halftone part

Claims (4)

(A) applying a photosensitive resist composition containing (A) an alkali-soluble resin, (B) a quinonediazide group-containing compound, (C) a solvent, and (D) a phenol compound to a substrate to form a resist film;
(B) exposing the resist film through a mask having a halftone portion;
(C) a step of developing the exposed resist film by bringing a developer into contact therewith,
In a resist pattern forming method including:
(D) The pattern forming method, wherein the phenol compound is a condensate of phenols and α, α′-2-substituted xylenes. Phenols are represented by the general formula (I)

(In formula, R < ¹ > -R < ³ > shows a hydrogen atom or a C1-C4 alkyl group each independently.)
In which α, α′-2 substituted xylenes are represented by the general formula (II)

(Wherein R ^{4 to} R ¹¹ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X ¹ and X ² each independently represent a hydroxyl group, a toluenesulfonyloxy group, a methanesulfonyloxy group, or An alkoxy group having 1 to 4 carbon atoms is shown.)
The pattern formation method of Claim 1 which is a compound represented by these.   The pattern forming method according to claim 1, wherein the solvent (C) is mainly composed of propylene glycol monomethyl ether acetate. The pattern forming method according to claim 1, wherein the substrate used in the step (a) is a substrate for manufacturing a TFT array.

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