KR20040079095A - Photoresist composition for liquid crystal displays - Google Patents

Abstract

PURPOSE: A photoresist composition for the circuit of a liquid crystal display (LCD) device, a method for forming a photoresist pattern for LCD using the composition and an LCD containing the pattern formed by the method are provided, to reduce the width of CD skew decrease of pattern after Cr etching, thereby improving production yield and productivity. CONSTITUTION: The photoresist composition comprises 10-25 wt% of a novolac resin having a molecular weight of 2,000-12,000; 0.5-6.5 wt% of an acryl resin having a molecular weight of 2,000-25,000 (whose amount is 5-25 wt% based on the amount of the total resin); 3-10 wt% of a diazide-based photosensitive compound; and the balance of an organic solvent. Preferably the diazide-based photosensitive compound is 2,3,4,4'-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate.

Description

Photoresist composition for liquid crystal display circuits {PHOTORESIST COMPOSITION FOR LIQUID CRYSTAL DISPLAYS}

The present invention relates to a photoresist composition for a liquid crystal display device circuit, and more particularly, to improve productivity by reducing the width of CD skew reduction of a pattern in an S / D 4 mask process during the manufacturing process of a liquid crystal display device. It relates to a photoresist composition that can be.

In general, the S / D Less Mask process performs two wet etches, one dry etch, and one dry etch and PR etch back to reduce the Cr line width of the data line. There are many.

In order to minimize the reduction of the S / D line width, the side etch during wet etching should be reduced (ie, the adhesion of PR should be improved), and the active layer dry etching and PR The reduction in the line width of the photoresist at the time of etch back should be minimized (where a three layer film is a film composed of three layers of gate insulating film / amorphous silicon / n + amorphous silicon).

Therefore, the development of a photoresist capable of minimizing the defect problem due to the increase of the etching skew of Cr after the second Cr etching is required, but there are no photoresist to be satisfied.

The present invention provides a photoresist composition for a liquid crystal display device circuit that can minimize the etching skew after Cr etching by minimizing the reduction of the S / D line width in order to solve the problems in the prior art as described above. For the purpose of

Another object of the present invention is to provide a method of forming a photoresist pattern using the photoresist composition and a liquid crystal display including the pattern.

Figure 1 shows the analysis point in each glass after the four mask process,

2 is a result of comparing the cross-sectional SEM image at the CC1 position shown in Figure 1 with respect to the photoresist of the embodiment of the present invention and the conventional comparative example,

3 is a result of comparing the line width change of each step of the photoresist with respect to the photoresist of the embodiment of the present invention and the conventional comparative example.

In order to achieve the above object, the present invention (a) 10 to 25% by weight of a novolak resin having a molecular weight of 2000 to 12000; (b) 0.5 to 6.5 weight percent of an acrylic resin having a molecular weight of 2000 to 25000 of 5 to 25 weight percent of the total resin content; (c) 3 to 10% by weight of the diazide photosensitive compound; And (d) provides a photoresist composition for a liquid crystal display circuit comprising the remaining amount of the organic solvent.

In another aspect, the present invention provides a method for forming a photoresist pattern for an LCD comprising applying a photoresist composition on a silicon wafer and glass, and then exposing and developing the photoresist using a photomask to form a pattern in the imaging layer.

In another aspect, the present invention provides a liquid crystal display device comprising a photoresist pattern formed by the above method.

Hereinafter, the present invention will be described in detail.

The present invention has a feature of providing a photoresist composition including the acrylic resin capable of minimizing Cr etch skew after secondary Cr etching in an S / D Less Mask process.

The photoresist composition of the present invention includes a novolak resin, an acrylic resin having a specific molecular weight, a diazide photosensitive compound, and an organic solvent.

The novolak resin used in the present invention is produced by the polycondensation reaction of a phenol compound and an aldehyde compound. As said phenol, phenol, m-cresol, p-cresol, etc. can be used individually or in mixture of 2 or more types. As the aldehydes, formaldehyde, benzaldehyde, acetaldehyde and the like can be used. An acid catalyst may be used for the condensation reaction of the phenols and aldehydes. It is preferable that the molecular weight of such a novolak resin is 2000-12000, and the content is used in 10 to 25weight%. If the content of the polymer resin is less than 10% by weight, the viscosity is too low, there is a problem in the application of the desired thickness, if it exceeds 25% by weight there is a problem that the uniform coating of the substrate is difficult to be too high.

In the present invention, in order to control the side etching amount during the wet etching, it is preferable to use an adhesive improving additive. In addition, a method of improving the profile of the PR is used to minimize the line width reduction of the PR during the active layer dry etching and PR etch back. That is, by setting the profile of the PR, the step is reduced when the PR is consumed, but the decrease in the line width at that time can be minimized. Therefore, in order to maintain such a profile of PR, heat resistance that can maintain the profile at the time of exposure even after hard baking (H / B) is required, so the present invention can improve the heat resistance by using an acrylic resin having a specific molecular weight. Can be. In addition, the present invention can improve the adhesion by applying the acrylic resin can obtain a good result in terms of wet etching (Wet Etch).

Therefore, the present invention is characterized in that an acrylic resin having a molecular weight of 2000 to 25000 is used at 0.5 to 6.5% by weight based on the total composition.

The acrylic resin is preferably used in 5 to 25% by weight of the total resin content. When the content of the acrylic resin is less than 5% by weight of the total resin content, there is no effect on improving the profile, improving heat resistance and improving the adhesiveness, and when it exceeds 25% by weight, a strip problem occurs or a scum is There is a problem that occurs.

In addition, the photoresist composition of the present invention contains a diazide photosensitive compound as a photosensitive agent. The diazide photosensitive compound is not particularly limited, but may be reacted with a diazide compound such as polyhydroxy benzophenone, 1,2-naphthoquinone diazide and 2-diazo-1-naphthol-5-sulfonic acid. 2,3,4,4'tetrahydroxybenzophenone-1,2 prepared by esterifying tetrahydroxy benzophenone and 2-diazo-1-naphthol-5-sulfonic acid. -It is preferable to use naphthoquinone diazide-5-sulfonate. It is preferable to use the content of the said diazide type photosensitive compound at 3 to 10 weight% with respect to the whole composition.

In addition, the photoresist composition of the present invention contains the remaining amount of the organic solvent. Specific examples of the organic solvent include propylene glycol methyl ether acetate (hereinafter referred to as PGMEA), ethyl lactate (EL), 2-methoxyethyl acetate (MMP), propylene glycol monomethyl ether (PGME), and 3- Methoxybutyl acetate, 4-butyrolactone, etc. can be mixed or used independently.

In addition, the photoresist composition for a liquid crystal display circuit of the present invention may be coated with a substrate by adding additives such as colorants, dyes, anti-scratching agents, plasticizers, adhesion promoters, surfactants, and the like, according to the characteristics of individual processes. It can also improve performance.

The present invention also provides a method of forming a photoresist pattern for an LCD comprising applying the photoresist composition on a silicon wafer and glass, and then exposing and developing the photoresist using a photomask to form a pattern in the imaging layer.

In the present invention, the photoresist solution is spin-coated on a silicon wafer and then subjected to an electrothermal treatment for 90 to 120 seconds on a 90 to 120 ° C. hot plate. After exposing this using an exposure apparatus, it is developed using the tetramethylammonium hydroxide aqueous solution as a developing solution, and after a 90 second post-heating process on a 110-120 degreeC hotplate, it can be used for acquiring a photoresist image. .

Accordingly, the present invention can provide a liquid crystal display device, preferably a TFT-LCD having excellent sensitivity and a residual film ratio, including a photoresist pattern manufactured by the above method.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are for illustrating the present invention and the present invention is not limited by the following examples.

EXAMPLE

2,3,4,4-tetrahydroxybenzophenone-1,2- with 20 wt% of a novolak resin having a molecular weight of 5000 as a base polymer, 5 wt% of an acrylic resin having a molecular weight of 20000, and a diazide photosensitive compound 5% by weight of naphthoquinone diazide-5-sulfonate and 70% by weight of PGMEA as an organic solvent were added to a reactor equipped with a cooling tube and a stirrer, and stirred at 40 rpm at room temperature to prepare a photoresist composition.

The photoresist composition prepared above was added dropwise onto a glass substrate of 0.7T (thickness, 0.7 mm), rotated at a constant rotational speed, and then heated and dried at 115 ° C. for 90 seconds to form a film film having a thickness of 1.50 μm. It was. After mounting a mask of a predetermined shape on the film film, it was irradiated with ultraviolet rays. It was immersed in an aqueous solution of tetramethylammonium hydroxide 2.38% for 60 seconds to remove the portion exposed to ultraviolet light to form a photoresist pattern.

[Comparative Example]

In general, a photoresist pattern was formed using an LCD photoresist composition used in a line.

Experimental Example

1) Sensitivity and Residual Rate Evaluation

The sensitivity and the residual film ratio of the photoresist patterns of the Examples and Comparative Examples were measured by conventional methods, and the results are shown in Table 1 below.

Comparative example Example Photo speed (msec) 73 65 Retention rate (%) 89 94

As shown in Table 1, in the case of the embodiment of the present invention, the sensitivity is faster than the comparative example and the residual film ratio is also improved.

2) Mass production line test result

The evaluation contents and sample conditions were performed by splitting the four mask process step by step in the L4 line as follows, and performing a CD skew test on the photoresist of the comparative example and the example.

① Comparative example

# 1 S / D photo ADI stage

# 2 After 1st Cr Etch

# 3 After Active Layer Dry Etch & PR Etch Back

After # 4 H / B

# 5 After 2nd Cr Etch & PR Strip

② Example

# 6 S / D photo ADI stage

# 7 after 1st Cr etching

After # 8 Active Layer Dry Etch & PR etch back

After # 9 H / B

# 10 After 2nd Cr Etch & PR Strip

* analysis

: Center parts CC1 and CC2 and edge parts EE and EC were analyzed and compared as shown in FIG. 1.

A cross-sectional SEM image comparison result at the CC1 position is shown in FIG. 2. 2, the PR of the Example was higher than that of the Comparative Example in the photoresist profile angle, showing an improved result.

In addition, the comparison result of the line width change of PR for each step example and the comparative example is shown in Table 2 and FIG.

Item Process steps Comparative example Example EE EC CC1 CC2 Ave EE EC CC1 CC2 Ave PR line width comparison ADI 9.750 9.703 9.539 9.609 9.650 8.835 8.906 8.789 8.8823 8.853 Primary Cr Etching 9.585 9.281 9.210 9.328 9.351 8.882 8.742 8.695 8.742 8.765 Three Layer Etch and PR E / B 7.078 6.843 6.609 6.609 6.785 6.703 6.817 6.445 6.632 6.649 H / B 6.937 6.843 6.843 7.007 6.908 6.796 6.750 6.975 6.609 6.783 Cr line width comparison PR strip 5.555 5.578 5.367 5.625 5.531 5.203 5.391 5.086 5.297 5.244 ADI PR line width-Cr line width after PR strip ADI PR line width-Cr line width after PR strip 4.195 4.125 4.182 3.984 4.119 3.632 3.515 3.703 3.585 3.609

In the results of Table 2 and Figure 3, in the case of the conventional comparative example showed a phenomenon that the line width is reduced by about 0.3 um after the first Cr etching, in the case of the embodiment of the present invention it is found that the line width is changed to about 0.1 um or less to be relatively stable Can be.

In addition, the decrease in PR line width after the active etching and PR etch back (etch back) progress is 2.566 um in the comparative example, the embodiment is 2.116 um, the PR of the example is reduced by 0.450 um less to reduce the line width It can be seen that there is an effect.

In addition, the difference between the ADI (After Development Inspection) PR line width and the final Cr line width (Cr skew surface of Cr is 4.119 um for the comparative example, 3.609 um for the example, and the embodiment has a skew surface of about 0.510 um). Appeared small.

As described above, the photoresist composition for a liquid crystal display device circuit of the present invention improves the production yield and productivity by reducing the width of the CD skew reduction of the pattern in the S / D 4 mask process to improve the process margin You can.

Claims (4)

(a) 10 to 25% by weight of a novolak resin having a molecular weight of 2000 to 12000; (b) 0.5 to 6.5 weight percent of an acrylic resin having a molecular weight of 2000 to 25000 of 5 to 25 weight percent of the total resin content; (c) 3 to 10% by weight of the diazide photosensitive compound; And (d) remaining residual amount of organic solvent. The method of claim 1, The diazide photosensitive compound is a 2,3,4,4'tetrahydroxybenzophenone-1,2-naphthoquinone diazide-5-sulfonate. A method of forming a photoresist pattern for an LCD comprising applying a photoresist composition of claim 1 onto a silicon wafer and glass, and then exposing and developing the photoresist using a photomask to form a pattern in the imaging layer. A liquid crystal display device comprising the photoresist pattern of claim 3.