KR101325740B1 - Photoresist and method for forming photoresist pattern using the same - Google Patents

Abstract

The present invention comprises a polymer resin, a photosensitive compound and a solvent, the polymer resin is represented by the following formula (1),

≪ Formula 1 >

The R ₁ , R ₂ , R ₃ , R ₄ is a hydrogen atom or an alkyl group, at least one of R ₁ , R ₂ , R ₃ , R ₄ includes an alkylol cresol novolak resin, characterized in that a hydroxy alkyl group It provides a photoresist characterized in that. Accordingly, the present invention can produce a photoresist pattern having excellent film thickness uniformity and adhesion by improving the flowability and adhesion of the photoresist.

Photoresist, Photosensitive, Novolac, Cresol, Polymer, Coating, Slit Coating, Pattern

Description

Photoresist and method for manufacturing photoresist pattern using same {Photoresist and method for forming photoresist pattern using the same}

1 is a schematic perspective view showing a situation of applying a photoresist by slit coating.

2 is a process flowchart showing a method of manufacturing a photoresist pattern according to the present invention.

3A to 3E are cross-sectional views illustrating a process of forming a circuit pattern using a photoresist pattern according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10 substrate 20 slit die

30: slit nozzle 40: photoresist

The present invention relates to a photoresist, and more particularly, to a photoresist capable of improving thickness uniformity and adhesion of a photoresist coating film and a method of manufacturing a photoresist pattern using the same.

Liquid crystal displays (LCDs) not only have low power consumption and low driving voltage, but also display images close to cathode ray tubes (CRTs), so the demand is rapidly increasing. Widely used.

Such liquid crystal displays are expanding not only to notebooks, monitors, and home TVs, but also to various small and medium sized display devices, and also due to the increasing demand for liquid crystal displays, it is necessary to increase the size of glass substrates and increase the definition of liquid crystal display panels. have.

The fine circuit pattern of the liquid crystal display device uniformly coats or applies a photoresist to an insulating film or a conductive metal film formed on a substrate, and exposes and develops the coated photoresist under a mask of a predetermined shape to form a pattern of a desired shape. . Thereafter, the insulating film or the metal film is etched using the patterned photoresist film as a mask, and then the remaining photoresist film is removed to form a fine circuit on the substrate.

In general, the process error of the liquid crystal display device mainly occurs in a photolithography process using the above photoresist. If the photoresist is not uniformly applied, a difference in resolution and circuit line width may occur in a later process, and a difference in reflectance may also occur, resulting in a defect that appears on the screen as it is. In addition, when the adhesiveness of the photoresist is poor, a peeling phenomenon occurs in which the photoresist pattern formed through the exposure and development process is out of position in a later process, resulting in a poor process and lowering reliability. In particular, a hydrophilic metal such as Mo used in low resistance wiring has a problem in that the photoresist pattern is easily peeled off by physical force during a drying process using nitrogen or air when the adhesion of the photoresist is poor.

Therefore, the characteristics required for the photoresist for the formation of the circuit pattern should be excellent in adhesion with the lower layer while obtaining a uniform coating film thickness when applying the photoresist.

Methods of applying photoresist on a substrate include spin coating, roll coating, slit coating, and the like. Spin coating is a method of applying a photoresist to a substrate by centrifugal force by placing a substrate on a support of a disc, dropping a photoresist in the center of the substrate, and then rotating the substrate. Roll coating is a method of applying a photoresist by loading the photoresist outside the round roll and then moving the roll in a predetermined direction on the substrate. However, the spin coating and the roll coating are difficult to apply to a large glass substrate, and there is a problem in that a difference in coating film thickness or stain occurs.

Slit coating is a method of applying a photoresist through a micro nozzle using nitrogen pressure while the slit die, which has a fine nozzle groove of several tens to hundreds of micrometers, is applied to ensure uniform film thickness. However, since the amount of photoresist can be greatly reduced, it is mainly used for manufacturing large flat panel display devices.

Since the photoresist for the slit coating does not have a separate planarization process by rotation or roll, it must be excellent in flowability to spread uniformly in a short time for uniformity of the film thickness. Conventionally, for this purpose, the slit coating is performed by simply lowering the viscosity of the photoresist, but this does not fundamentally improve the flowability of the photoresist, and when the viscosity is excessively low, there is a problem in that the thickness uniformity of the coating film is lowered.

The present invention is to solve the above problems, by improving the flowability of the photoresist, to improve the thickness uniformity of the coating film when applying the photoresist and excellent adhesion to the photoresist and a method for producing a photoresist pattern using the same It aims to provide.

The present invention comprises a polymer resin, a photosensitive compound and a solvent, in order to achieve the above object, the polymer resin is represented by the following formula (1),

&Lt; Formula 1 >

The R ₁ , R ₂ , R ₃ , R ₄ is a hydrogen atom or an alkyl group, at least one of R ₁ , R ₂ , R ₃ , R ₄ includes an alkylol cresol novolak resin, characterized in that a hydroxy alkyl group It provides a photoresist characterized in that. R ₁ , R ₂ , R ₃ , and R ₄ may be a methyl, ethyl, propyl or isopropyl group, and at least one may be a hydroxy alkyl group.

The weight average molecular weight of the polymer resin is preferably 3000 to 10000, the polymer resin may further comprise a cresol novolak resin.

The polymer resin is 10 to 20% by weight, the photosensitive compound is preferably 2 to 10% by weight, the solvent is preferably 60 to 90% by weight.

The photosensitive compound may include a diazide compound, and the solvent may include propylene glycol methyl ether acetate (PGMEA).

The present invention provides a method of manufacturing a photoresist pattern comprising applying the above-described photoresist on a substrate, exposing the applied photoresist coating film and developing the exposed photoresist coating film.

Hereinafter, a photoresist according to an embodiment of the present invention will be described in detail.

The photoresist of this invention contains a polymeric resin, a photosensitive compound, and a solvent. Here, the polymer resin is 10 to 20% by weight, the photosensitive compound is preferably 2 to 10% by weight, the solvent is preferably 60 to 90% by weight.

The polymer resin includes an alkylol cresol novolak resin in which an alkylol cresol novolak is substituted for a novolak monomer at a terminal of a conventional novolak resin. The structure of this alkylol cresol novolak resin is represented by the following formula (1).

In Formula 1, R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen atoms or alkyl groups, and at least one of R ₁ , R ₂ , R ₃ , and R ₄ is a hydroxy alkyl group.

The polymer resin having such a structure replaces at least one of R ₁ , R ₂ , R ₃ , and R ₄ with a hydroxy group than the conventional novolak resin, thereby controlling the polarity of the polymer resin to improve contact characteristics with the metal film. It can be greatly improved. In particular, in the case of a hydrophilic metal such as Mo used for low resistance wiring, the wettability of the photoresist is increased, thereby improving the flowability during the application of the photoresist, thereby improving the thickness uniformity of the coating film and improving the adhesion. Increases.

The polymer resin of the present invention may be composed of only the above alkylol cresol novolak resin, or may be mixed with an existing novolak resin.

It is preferable that the said polymer resin is the molecular weight of 3000-10000. If the molecular weight is less than 3000, the speed of dissolving in the developer is difficult to control the sensitivity, and if the molecular weight exceeds 10000, the dissolution rate is slow and there is a difficulty in forming a pattern at the desired sensitivity.

The polymer resin according to the present invention is contained 5 to 30% by weight in the photoresist, preferably 10 to 20% by weight as mentioned above. When the content of the polymer resin is less than 5% by weight, the viscosity is too low, there is a problem that the coating of the desired thickness is difficult, and when it exceeds 30% by weight, the viscosity is too high, it is difficult to uniform coating on the substrate.

The photosensitive compound includes a diazide compound. The diazide compound is 2,3,4, -trihydroxybenzophenone-1,2-naphtho prepared by esterifying a trihydroxy benzophenone and 2-diazo-1-naphthol-5-sulfonic acid. Quinonediazide-5-sulfonate or 2,3,4,4'-tetrahydroxybenzophenone prepared by esterification of tetrahydroxy benzophenone and 2-diazo-1-naphthol-5-sulfonic acid 1,2-naphthoquinonediazide-5-sulfonate can be used individually or in mixture.

The diazide-based photosensitive compound plays a role in controlling the photosensitive speed of the photoresist of the present invention. By controlling the amount of the diazide-based photosensitive compound contained in the photoresist, the photosensitive speed of the photoresist can be selectively controlled. In addition, the degree of esterification of 2-diazo-1-naphthol-5-sulfonic acid reacted with 2,3,4, -trihydroxybenzophenone or 2,3,4,4'-tetrahydroxybenzophenone is also controlled. By doing so, the photosensitive speed of the photoresist can be selectively controlled.

The photosensitive compound according to the present invention is preferably contained in 2 to 10% by weight in the photoresist. When the content of the photosensitive compound is less than 2% by weight, the photoresist speed is too fast to reduce the residual film rate, that is, the loss rate of the portion where the non-exposed portion remains as a photoresist pattern during development is reduced, and exceeds 10% by weight. In this case, there is a problem that the photosensitive speed of the photoresist is too slow.

The photosensitive compound may be adjusted according to the content of the polymer resin, preferably 20 to 50% by weight of the polymer resin content.

The solvent is for making the polymer resin and the photosensitive compound in a solution state capable of coating, and when the slit coating, it is preferable to use a solvent having excellent flowability.

The solvent mainly uses propylene glycol methyl ether acetate (PGMEA). The PGMEA also contains ethyl lactate (EL), propylene glycol monomethyl ether (PGME), ethyl cellsolve-acetate (ECA), gamma-butyrolactone (GBL), 2-methoxyethyl acetate (MMP), ethyl beta -Ethoxy propionate (EEP), normal propyl acetate (nPAC), normal butyl acetate (nBA), etc. can be mixed and used.

The solvent according to the invention is preferably included in the photoresist 60 to 90% by weight. When the content of the solvent is less than 60% by weight, there is a problem that staining occurs because the content of the solid content is increased, and when the content of the solvent exceeds 90% by weight, there is a problem that the residual film rate is lowered.

As described above, the photoresist of the present invention contains a polymer resin containing an alkylol cresol novolak resin, a diazide photosensitive compound, and a solvent. In addition, additives such as colorants, dyes, anti-scratching agents, plasticizers, adhesion promoters, and surfactants may be further included according to the desired purpose.

The photoresist of the present invention can improve the contact characteristics with the metal film by controlling the polarity of the polymer resin. Accordingly, the adhesion of the photoresist may be improved, and the flow uniformity of the photoresist may be improved to improve thickness uniformity of the coating layer. In particular, the photoresist of the present invention has an advantage in that excellent film thickness uniformity and adhesiveness can be obtained by applying to a slit coating requiring flowability to spread uniformly within a short time.

Brief description of the production of a photoresist according to an embodiment of the present invention is as follows.

First, an alkylol cresol novolac resin, which is a polymer resin of the present invention, is synthesized. The alkylol cresol novolak resin is obtained by condensation reaction of an alkylol cresol monomer with formaldehyde under an acid catalyst. The manufacturing process for this is the same as the conventional manufacturing process of cresol novolak resin, but proceeds by further mixing the alkylol cresol during or at the end of the reaction. Thus, an alkylol cresol novolak resin in which an alkylol cresol monomer is substituted in place of the novolak monomer at the end of the existing novolak resin can be prepared.

As mentioned above, the polymer resin of the present invention may include the alkylol cresol novolak resin, or may further include an existing novolak resin.

Conventional novolak resins are obtained by condensation reaction of a cresol monomer with formaldehyde under an acid catalyst, and the cresol may be meta cresol, para cresol, ortho cresol, xyleneol and the like. Multiple cresols may be used by mixing. For example, meta cresol and para cresol can be mixed, where meta cresol tends to speed up photosensitis and para cresol tends to slow down photosensitization.

The polymer resin and the photosensitive compound prepared as described above are added to a solvent, followed by stirring at room temperature to prepare a photoresist. This is the same as a known technique, but the detailed description is omitted.

Hereinafter, the manufacturing method of the photoresist pattern which concerns on embodiment of this invention is demonstrated.

The above-described example illustrates the formation of a photoresist pattern using a slit coating, but is not limited thereto, and the photoresist of the present invention is a substrate according to a conventional coating method including dipping, spraying, rotating, spin, and roll coating. Of course, it can be applied to.

1 is a schematic perspective view showing a situation of applying a photoresist by slit coating.

Referring to FIG. 1, the slit die 20 moves while spraying the photoresist 40 to the substrate 10 by a predetermined amount through the slit nozzle 30 therein to apply the photoresist 40. Such a slit coating has an advantage of ensuring uniformity of the film thickness and greatly reducing the amount of photoresist used.

The substrate 10 may include silicon, aluminum, indium tin oxide (ITO), indium zinc oxide (IZO), molybdenum, chromium, silicon dioxide, doped silicon dioxide, silicon nitride, tantalum, copper, polysilicon, ceramic, aluminum / And an insulating film or a metal film made of a copper mixture and various polymerizable resins.

2 is a process flowchart showing a method of manufacturing a photoresist pattern according to the embodiment of the present invention.

First, the photoresist of the present invention described above is applied to a substrate by slit coating (S10).

As described above, a soft bake process for heating the photoresist coated on the substrate to a predetermined temperature is performed (S20), and the soft bake process is performed at a temperature of 80 to 130 ° C. This is to evaporate the solvent without pyrolyzing the solid component of the photoresist, and most of the solvent is evaporated until the thin coating film of the photoresist having a thickness of 3 μm or less remains.

Next, a pattern having a desired shape is formed by exposing the substrate on which the photoresist film is formed to light, particularly ultraviolet rays, using a mask having a predetermined pattern (S30). Thereafter, the photoresist film is developed using a developer (S40).

In addition, in order to enhance adhesion and chemical resistance of the remaining photoresist film after cleaning the substrate having completed the development process, a hard bake process is performed at a predetermined temperature (S50), and the hard bake The process takes place at a temperature of 90 to 140 ° C.

Through this process, the present invention can improve the film thickness uniformity and adhesion, and can produce a photoresist pattern excellent in resolution and line width.

3A to 3E are cross-sectional views illustrating a process of forming a circuit pattern using a photoresist pattern according to an embodiment of the present invention.

Referring to FIG. 3A, a lower layer 110 for forming a circuit pattern is formed on the substrate 100.

The lower layer 110 includes silicon, aluminum, indium tin oxide (ITO), indium zinc oxide (IZO), molybdenum, chromium, silicon dioxide, doped silicon dioxide, silicon nitride, tantalum, copper, polysilicon, ceramic, aluminum It may include an insulating film or a metal film made of a / copper mixture and various polymerizable resins.

As shown in FIG. 3B, the above-described photoresist 120 is applied to the upper surface of the lower layer 110 to perform a soft bait process so that most solvents are evaporated.

Next, the photoresist 120 is exposed and developed using a mask on which a predetermined pattern is formed, and then a hard bake process is performed to form the photoresist 120 pattern on the upper surface of the lower layer 110 as shown in FIG. 3C. Form.

Referring to FIG. 3D, a substrate is treated with a corrosion solution or a gas plasma using the photoresist 120 pattern manufactured as described above as a mask, and thus, a predetermined portion of the lower layer 110 exposed due to the absence of the photoresist 120 pattern is present. Etch the site. At this time, the portion of the lower layer 110 that is not exposed is protected by the photoresist 120 pattern.

As such, when the lower layer 110 is etched and the photoresist 120 pattern is removed with an appropriate stripper, as shown in FIG. 3E, a fine circuit pattern having a desired shape may be formed on the substrate 100.

Hereinafter, the present invention will be described in more detail with reference to examples.

[Comparative Example]

10% by weight of a cresol novolac resin having a weight average molecular weight of 7000 prepared by condensation of a cresol monomer and formaldehyde mixed at a meta cresol and para cresol ratio under an oxalic acid catalyst with naphthoquinone diazide sulfonic acid as a photosensitive compound The solid consisting of 5% by weight of the ester was dissolved in 85% by weight of PGMEA solvent, and then filtered through a 0.2 µm filter to prepare a photosensitive resin.

[Example 1]

5% by weight of cresol novolac resin and 5% by weight of alkylol cresol novolak resin having a weight average molecular weight of 7000 prepared by condensation reaction of a cresol monomer and formaldehyde mixed at a meta cresol and para cresol ratio at 6: 4 under an oxalic acid catalyst; , A solid composed of 5% by weight of naphthoquinone diazide sulfonic acid ester as the photosensitive compound was dissolved in 85% by weight of PGMEA solvent, and then filtered through a 0.2 μm filter to prepare a photosensitive resin.

[Example 2]

10 wt% of an alkylol cresol novolak resin having a weight average molecular weight of 7000 prepared by condensation of an alkylol cresol monomer and formaldehyde under an oxalic acid catalyst, and a solid comprising 5 wt% of naphthoquinone diazide sulfonic acid ester as a photosensitive compound After dissolving in 85% by weight of PGMEA solvent, it was filtered through a 0.2 μm filter to prepare a photosensitive resin.

Comparative Examples, Example 1 and Example 2 were prepared by changing the photosensitive compound and the solvent to the same material, the same amount, the polymer resin, and compared the properties accordingly.

Table 1 below shows the results of measuring the thickness variation of the coating film after the slit coating of the photoresist prepared according to Comparative Examples and Examples 1 and 2 on the Mo thin film is formed. Here, the thickness of the coating film was measured using a NANOSPEC M6500 film thickness measuring equipment, and showed the average thickness deviation through the third measurement.

As can be seen in Table 1, in Example 1 and Example 2 according to the present invention, it can be seen that the thickness uniformity is improved compared to the comparative example. This is because by replacing the alkylol cresol novolak instead of the novolak monomer at the end of the conventional novolak resin, by controlling the polarity of the polymer resin to improve the flowability during coating.

Table 2 below shows the results of peeling by pattern size after forming a photoresist pattern on a Mo thin film-formed substrate using the photoresist prepared according to Comparative Examples and Examples 1 and 2. That is, by exposing the photoresist of Comparative Examples and Examples 1 and 2 coated on the substrate on which the Mo thin film is formed as described above with ultraviolet rays using a predetermined mask and then developing with an aqueous alkali solution to perform a hard baking process, A photoresist pattern was formed.

Referring to Table 2, in the case of the comparative example, all of the pattern of the size of 2㎛, 3㎛, 4㎛ peeling occurred, in the case of Example 1 only the pattern of 4㎛ size occurred, 1 in Example 2 It can be seen that no patterning occurred in the patterns having a size of 2 μm, 2 μm, 3 μm, and 4 μm. That is, by including the alkylol cresol novolak resin according to the present invention, it can be seen that the adhesion of the coating film is improved compared to the conventional. Accordingly, there is an advantage in that process defects can be reduced to increase process stability and productivity, and reliability of pattern formation can be improved.

Table 3 below forms a photoresist pattern on a substrate on which a Mo thin film is formed using the photoresist prepared according to Comparative Examples and Examples 1 and 2, and then, etching the film using a strong acid for a predetermined time, The length was observed with the electron microscope.

As shown in Table 3, in Examples 1 and 2 according to the present invention, it can be seen that the over-etching area is smaller than that of the comparative example. Therefore, the present invention can produce a photoresist pattern having excellent resolution and line width due to the formation of an accurate pattern.

As described above, the photoresist of the present invention can improve the flowability and adhesion of the photoresist by controlling the polarity of the polymer resin by replacing the alkylol cresol novolac at the end of the existing novolak resin. Accordingly, it is possible to manufacture a photoresist pattern having excellent film thickness uniformity and adhesion, and there is an advantage of improving process stability and productivity and improving pattern formation reliability. In particular, the present invention has the advantage of producing a photoresist pattern having excellent film thickness uniformity and adhesion even when applied to a slit coating that requires flowability to spread uniformly within a short time.

As mentioned above, although this invention was demonstrated in detail using the preferable Example, the scope of the present invention is not limited to a specific Example and should be interpreted by the attached Claim. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention.

The present invention by controlling the polarity of the polymer resin by replacing the alkylol cresol novolak at the end of the conventional novolak resin, thereby improving the flowability and adhesion of the photoresist photoresist having excellent film thickness uniformity and adhesion Patterns can be produced. Accordingly, there is an advantage that can increase process stability and productivity and improve the reliability of pattern formation. In particular, the present invention has an advantage in that a photoresist pattern having excellent film thickness uniformity and adhesion may be manufactured by applying to a slit coating requiring flowability to spread uniformly within a short time.

Claims (8)

A polymer resin, a photosensitive compound and a solvent, The polymer resin is represented by the following formula (1), &Lt; Formula 1 >

At least one of R ₁ , R ₂ , R ₃ , and R ₄ is a hydroxy alkyl group, and the remainder of R ₁ , R ₂ , R ₃ , and R ₄ is a hydrogen atom or an alkyl group, wherein the alkylol cresol novolak resin is used. Photoresist comprising a. The method according to claim 1, At least one of R ₁ , R ₂ , R ₃ , and R ₄ is a hydroxy alkyl group, and the rest of R ₁ , R ₂ , R ₃ , and R ₄ is a methyl, ethyl, propyl, or isopropyl group. . The method according to claim 1 or 2, The weight average molecular weight of the polymer resin is 3000 to 10,000, characterized in that the photoresist. The method according to claim 1 or 2, The polymeric resin further comprises a cresol novolac resin. The method according to claim 1 or 2, The polymer resin is 10 to 20% by weight, the photosensitive compound is 2 to 10% by weight, the solvent is a photoresist, characterized in that 70 to 88% by weight. The method according to claim 1 or 2, The photosensitive compound is a photoresist comprising a diazide compound. The method according to claim 1 or 2, The solvent comprises propylene glycol methyl ether acetate (PGMEA). Applying a photoresist according to claim 1 or 2 on a substrate; Exposing the applied photoresist coating film; And And developing the exposed photoresist coating film.

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