JP3707708B2 - Positive photoresist coating solution - Google Patents

Description

【００２８】
注）ＭＢＡ：酢酸３‐メトキシブチル
ＭＢＭ：β‐メトキシイソ酪酸メチル
ＰＧＭＥＡ：プロピレングリコールモノメチルエーテルアセテート
ＥＬ：乳酸エチル
ＢＡ：酢酸ブチル[0001]
[Industrial application fields]
The present invention relates to a novel positive photoresist coating solution, and more particularly to a positive photoresist coating solution excellent in in-plane uniformity, wettability, adhesion, storage stability, and drying properties.
[0002]
[Prior art]
Conventionally, positive photoresist compositions have been frequently used in the manufacturing processes of semiconductor devices such as IC and LSI and liquid crystal devices such as LCD. The photoresist composition is composed of a film-forming resin, a photosensitive agent, and a solvent for dissolving them. From the purpose of use, it is desired that a coating film having a uniform film thickness and good adhesion can be obtained, wettability and dryability during application are good, and stable even when stored.
[0003]
Conventionally, ethylene glycol monoethyl ether acetate has been used as a solvent in a resist composition that satisfies the above physical properties. However, in recent years, the safety of resist solvents has been regarded as a problem, and propylene glycol monomethyl ether acetate, monooxymonocarboxylic acid ester, etc. are used alone as solvents with higher safety (Japanese Patent Laid-Open No. Sho 61-7837, special feature). No. 62-123444) or 2-heptanone or a mixed solvent with butyl acetate, which has been used with improved properties (JP-A-6-67420, JP-A-6-317901, JP-A-7-56333, JP-A-7-134401). However, even when used as a mixed solvent, a resist solution having sufficiently satisfactory physical properties for a recent large-sized substrate has not been obtained. In the future, 8 inch silicon wafers will become the mainstream, and in the future, the trend is toward 12 inches, so it is desirable to improve coating performance such as in-plane uniformity and wettability for increasingly larger substrates. ing.
[0004]
As mentioned earlier, the resist coating solution must be stopped by the production line for device preparation when foreign material, which is a photosensitive agent, is deposited during storage. There is a demand for a resist coating solution that is excellent in storage stability and does not generate odor.
[0005]
Since 3-methoxybutyl acetate is high in safety, has good solubility in the photosensitizer, and is excellent in preventing striation, a resist solution using this is known (Japanese Patent Laid-Open No. Sho 62-62). No. 5237, JP-A-3-127670).
[0006]
However, since this has a high boiling point and a low evaporation rate, and the drying process takes a long time, the solvent cannot be completely evaporated in the manufacturing process of a semiconductor device or a liquid crystal device, resulting in a decrease in throughput or a uniform film thickness. Since a film cannot be formed, it is not put into practical use.
[0007]
Thus, it has been proposed to use 3-methoxybutyl acetate as a mixed solvent with aromatic hydrocarbons such as xylene and esters such as ethyl acetate and butyl acetate (Japanese Patent Laid-Open No. 3-127067). There were drawbacks in that the solubility of the agent decreased and the striation increased.
[0008]
On the other hand, methyl β-methoxyisobutyrate is readily available, has good drying properties, and good solubility of the photosensitizer, so that it has been proposed to be used as a solvent for a resist solution (Japanese Patent Laid-Open No. 7-271023, JP-A-7-281429, JP-A-7-311459), methyl β-methoxyisobutyrate alone has insufficient in-plane uniformity, lack of wettability, and other solvents for improving characteristics. Even when used in a mixture, the coating solution using a solvent containing methyl β-methoxyisobutyrate in a proportion of 50% by weight or more is still wettable to a large hydrophobic substrate with a nitride film or the like. Has the disadvantage of being inferior.
[0009]
[Problems to be solved by the invention]
Under such circumstances, the present invention is capable of forming a uniform coating film thickness over the entire substrate, excellent in-plane uniformity, and good in wettability, adhesion and storage stability, In addition, the present invention has been made for the purpose of providing a positive photoresist coating solution having a drying property suitable for drying conditions in the manufacturing process of a semiconductor device or a liquid crystal device, an excellent throughput, and a high solvent safety.
[0010]
[Means for Solving the Problems]
As a result of intensive studies to develop a positive photoresist coating solution having excellent coating properties, the present inventors have used a mixture of 3-methoxybutyl acetate and methyl β-methoxyisobutyrate at a predetermined ratio as a solvent. By using it, it discovered that the said objective could be achieved and came to complete this invention based on this knowledge.
[0011]
That is, the present invention comprises (A) an alkali-soluble resin and (B) a quinonediazide group-containing compound (C) (ii) 3-methoxybutyl acetate 60 to 90% by weight, (b) methyl β-methoxyisobutyrate 40 to 10%. The present invention provides a positive photoresist coating solution which is dissolved in a mixed solvent consisting of 1%.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the coating solution of the present invention, the alkali-soluble resin used as the component (A) is not particularly limited, and any conventionally known alkali-soluble resin can be selected and used. Examples of the alkali-soluble resin include phenols such as phenol, m-cresol, p-cresol, xylenol, and trimethylphenol and aldehydes such as formaldehyde, formaldehyde precursor, 2-hydroxybenzaldehyde, 3-hydroxybenzaldehyde, and 4-hydroxybenzaldehyde. Novolak resin obtained by condensing alcohols in the presence of an acidic catalyst, a homopolymer of hydroxystyrene, a copolymer of hydroxystyrene and other styrene monomers, hydroxystyrene and acrylic acid or methacrylic acid or derivatives thereof And an alkali-soluble resin such as acrylic acid or methacrylic acid resin that is a copolymer of acrylic acid or methacrylic acid and a derivative thereof.
[0013]
In the coating solution of the present invention, the quinonediazide group-containing compound used as the component (B) is not particularly limited, and any quinonediazide group-containing compound conventionally used as a photosensitive component for resists can be selected and used. it can. Examples of the quinonediazide group-containing compound include 2,3,4-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3,5 -Dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxy Phenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -3,4-dihydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis ( 4-hydroxyphenyl) ethyl] benzene, 2- (2,3,4-to Hydroxy compounds such as hydroxyphenyl) -2- (2 ', 3', 4'-trihydroxyphenyl) propane and bis (2,3,4-trihydroxyphenyl) methane, naphthoquinone-1,2-diazidesulfonic acid There is an ester.
[0014]
The positive photoresist coating solution of the present invention contains the photosensitive component in an amount of 5 to 50 parts by weight, preferably 10 to 35 parts by weight, based on 100 parts by weight of the alkali-soluble resin. If the photosensitive component is less than 5 parts by weight, no image can be formed.
[0015]
In addition to the alkali-soluble resin and the photosensitive component, the positive photoresist coating solution of the present invention can be blended with a low molecular weight phenol compound for improving known sensitivity and resolution in some cases. Examples of this low molecular weight phenol compound include tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2, 5-Dimethylphenyl) -2-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl)- 3,4-dihydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, 2- (2,3,4-tri Hydroxyphenyl) -2- (2 ', 3', 4'-trihydroxyphenyl) propane, bi In addition to (2,3,4-trihydroxyphenyl) methane and the like, 2,6-bis [1- (2,4-dihydroxyphenyl) isopropyl] -4-methylphenol, 2,6-bis (2,3, 4-trihydroxyphenylmethyl) -4-methylphenol, 4,6-bis [1- (4-hydroxyphenyl) isopropyl] -resorcin. These low molecular weight phenol compounds are blended in an amount of 5 to 50 parts by weight, preferably 10 to 35 parts by weight, per 100 parts by weight of the alkali-soluble resin.
[0016]
Further, if necessary, compatible additives, UV absorbers for preventing halation, such as 2,2 ', 4,4'-tetrahydroxybenzophenone, 4-dimethylamino-2', 4'- Dihydroxybenzophenone, 5-amino-3-methyl-1-phenyl-4- (4-hydroxyphenylazo) pyrazole, 4-dimethylamino-4'-hydroxyazobenzene, 4-diethylamino-4'-ethoxyazobenzene, 4-diethylamino Azobenzene, curcumin, and the like, and surfactants for preventing striation, such as Fluorad FC-430, FC-431 (trade name, manufactured by 3M), Ftop EF122A, EF122B, EF122C, EF126 (trade name, Tochem Products) Fluorine-based surfactants, etc. It may contain additives in a range not interfering with the purposes of the present invention.
[0017]
In the coating solution of the present invention, the mixed solvent of 3-methoxybutyl acetate and methyl β-methoxyisobutyrate used as the component (C) must be a mixture ratio of 60 to 90% by weight of the former and 40 to 10% by weight of the latter. In particular, the mixing ratio of the former 70 to 90% by weight and the latter 30 to 10% by weight is preferable. If the proportion of 3-methoxybutyl acetate is higher than this, the evaporation rate during drying will be slow and the in-plane uniformity of the coating will deteriorate. If the proportion is small, the in-plane uniformity and wettability of the coating will be reduced. In addition, the solubility in a photosensitive agent, particularly a benzophenone-based photosensitive agent, is lowered, and the storage stability becomes insufficient.
[0018]
【The invention's effect】
The positive photoresist coating solution of the present invention has high solvent safety, can form a coating film having a uniform film thickness over the entire substrate, has excellent in-plane uniformity, and wettability, adhesion and storage. Since it has good stability and good drying properties, it can be suitably used in the manufacturing process of semiconductor devices such as IC and LSI, and liquid crystal devices such as LCD.
[0019]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Various physical properties of the positive photoresist coating solution were determined by the following methods.
[0020]
(1) In-plane uniformity:
The prepared positive photoresist coating solution is spinner-coated on a glass substrate (300 × 400 mm) on which a Cr film is formed to a film thickness of 1.85 μm, and then the hot plate temperature is set to 130 ° C. with an interval of about 1 mm. And dry for 60 seconds. Further, the temperature of the hot plate was set to 110 ° C., and drying was performed for 60 seconds to obtain a coating film. The film thickness of this coating film was measured at multiple points using nanospecs (manufactured by Nanometrics), and the in-plane uniformity was determined from the following formula. In addition, it means that uniformity is so high that this value is small.
[(Maximum film thickness−minimum film thickness) ÷ (2 × average film thickness)] × 100
[0021]
(2) Wetability A positive photoresist coating solution prepared by spinner coating on a 6-inch silicon wafer on which a nitride film (SiN) is formed, and then prebaked on a hot plate at a temperature of 110 ° C. for 60 seconds until the substrate edge The case where a uniform coating film was formed was evaluated as ◯, and the case where a coating film was not formed up to the substrate end was evaluated as x.
[0022]
(3) Adhesion:
The prepared positive photoresist coating solution is spinner-coated on a glass substrate on which a silicon oxide film (SiO ₂ ) is formed to a thickness of 1.6 μm, and then the temperature on the hot plate is set to 130 ° C. and about 1 mm. Dry for 60 seconds at intervals. Furthermore, the temperature of the hot plate was set to 110 ° C., drying was performed for 60 seconds, and exposure was performed using a contact exposure apparatus PLA-500F (manufactured by Canon Inc.) through a test mask pattern.
[0023]
Next, the exposed portion was removed by immersing in a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 65 seconds to form a resist pattern having a line width of 10 μm on the silicon oxide film, and then the temperature was increased on a hot plate. Post bake at 120 ° C. for 5 minutes, and expose the exposed silicon oxide film in an etching solution (7% aqueous solution containing a 1: 6 hydrofluoric acid: ammonium fluoride ratio by weight) using the resist pattern as a mask. The silicon oxide layer was etched by soaking for 10 minutes. Next, the adhesion between the resist pattern and the silicon oxide layer was evaluated according to the following criteria by observation with an electron microscope.
3 <X ≦ 5 is ○,
5 <X ≦ 7 is △,
7 <X ≦ 10 ×,
X (μm) = A−B, A represents the line width (10 μm) of the resist pattern used as an etching mask, and B represents the width of the silicon oxide film under the resist pattern remaining after the etching process. . The smaller X is, the better the adhesion between the resist pattern and the silicon oxide film is.
[0024]
(4) Storage stability The prepared positive photoresist coating solution was stored in a brown bottle sealed at room temperature for 1 month, and evaluated as good for good and poor for poor.
(5) Drying After the positive photoresist coating solution prepared by spinner coating on a silicon wafer and prebaking on a hot plate at a temperature of 110 ° C. for 60 seconds, the solvent is volatilized and the solvent remains. What was being evaluated was evaluated as x.
[0025]
Example 1
A cresol novolak resin (weight average molecular weight 10,000) obtained by mixing m-cresol and p-cresol in a weight ratio of 60:40, adding formalin thereto, and condensing by an ordinary method using an oxalic acid catalyst. ) 100 parts by weight, 27 parts by weight of the esterification reaction product of 1 mole of 2,3,4,4'-tetrahydroxybenzophenone and 2.5 moles of naphthoquinone-1,2-diazide-5-sulfonyl chloride are mixed with 3-acetic acid After dissolving in a mixed solvent of 266 parts by weight of methoxybutyl and 114 parts by weight of methyl β-methoxyisobutyrate (weight ratio 7: 3), this was filtered using a membrane filter having a pore size of 0.2 μm, and a positive photoresist coating solution Was prepared.
The physical properties of this product were measured, and the results are shown in Table 1.
[0026]
Example 2, Comparative Examples 1-6
A positive photoresist coating solution was prepared in the same manner as in Example 1 except that the solvent in Example 1 was changed to that shown in Table 1.
The physical properties of these materials were measured, and the results are shown in Table 1.
[0027]
[Table 1]

[0028]
Note) MBA: 3-methoxybutyl acetate MBM: methyl β-methoxyisobutyrate PGMEA: propylene glycol monomethyl ether acetate EL: ethyl lactate BA: butyl acetate

Claims (1)

(A) An alkali-soluble resin and (B) a quinonediazide group-containing compound are mixed into a mixed solvent comprising (C) (ii) 60 to 90% by weight of 3-methoxybutyl acetate and (b) 40 to 10% by weight of methyl β-methoxyisobutyrate. A positive photoresist coating solution which is dissolved.