WO2006104340A1

WO2006104340A1 - Thinner composition for removing photoresist

Info

Publication number: WO2006104340A1
Application number: PCT/KR2006/001138
Authority: WO
Inventors: Hee-Jin Park; Sung-Gun Shin; Suk-Il Yoon; Byung-Uk Kim
Original assignee: Dongjin Semichem Co., Ltd.
Priority date: 2005-03-31
Filing date: 2006-03-29
Publication date: 2006-10-05
Also published as: KR20060104688A; TW200702945A

Abstract

The present invention relates to a thinner composition for removing photoresist used in the manufacture of semiconductor devices or liquid crystal displays. The composition includes a) propylene glycol monoalkyl ether acetate, b) alkyl lactate, and c) y-butyrolactone. The thinner composition of the present invention may further include at least one compound selected from the group consisting of d) a polyethylene oxide-based surfactant, and e) a fluorinated acrylic copolymer. The thinner composition for removing photoresist in accordance with the present invention is capable of effectively removing unwanted photoresist at the edge and back of glass substrates for organic ELs, as well as those used for manufacturing display devices, in a short period of time regardless of the particular photoresist used.

Description

THINNER COMPOSITION FOR REMOVING PHOTORESIST BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a thinner composition for removing

photoresist, and more particularly to a thinner composition that is capable of

effectively removing unwanted photoresist in a manufacturing process of semiconductor devices or liquid crystal displays.

(b) Description of the Related Art

The TFT-array process in the manufacture of TFT-LCDs (thin film transistor liquid crystal displays) is similar to the silicon semiconductor manufacturing process

using photolithography. The photolithographic process is a process for coating a photoresist film on a substrate, transcribing and developing a photomask pattern, and etching the substrate to obtain an electronic circuit.

To manufacture a TFT-LCD by the photolithographic process, a TFT-array needs to be formed on a substrate. In the process, the thinner composition may

penetrate into the interface of the photoresist, resulting in several defects in following processes, such as etching or ion implantation, and a decrease of the

overall production yield.

The penetration of the thinner composition into the interface of the photoresist becomes a cause of defocusing during light exposure following the baking process, and lowers the yield of TFT-LCD manufacture.

In contrast with the round edge of a silicon wafer, where centrifugal force is applied, the glass substrate of the TFT-LCD has a square edge, and thus removal of photoresist by spin EBR (edge bead removal) is impossible. Also, since the glass substrate is fixed and the injection nozzle travels rectilinearly along the four edges of the glass substrate, retarded evaporation after the photoresist has been coated may lead to penetration into the interface of the photoresist even after the photoresist has been removed at the edge. This presents a sharp contrast with the spin EBR, in which even a less volatile thinner can be prevented from penetrating into the interface of the photoresist if the silicon wafer is spun at a high rate. That is, as the

LCD glass substrate is fixed and only the thinner injection nozzle moves, use of the conventional highly-soluble thinners for rinsing results in penetration into the interface of the photoresist at the edge and lowers the overall production yield. Such conventional thinner compositions are as follows. Japanese Patent Laid-Open No. Sho 63-69563 discloses a method of removing unwanted photoresist by contacting a thinner at the substrate. This patent uses an organic solvent, for example ethers and ether acetates such as cellosolve, cellosolve acetate, propylene glycol ether, and propylene glycol ether acetate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and esters such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, and butyl acetate as a thinner. Japanese Patent Laid-Open No. Hei 4-49938 discloses the use of propylene glycol methyl ether acetate as a thinner, and

Japanese Patent Laid-Open No. Hei 4-42523 discloses the use of alkyl alkoxy propionate as a thinner.

These solvents have been used alone or admixed with one another to improve physical properties and stability. They have been used in the manufacture of semiconductor devices in which EBR is performed at a high spinning rate, rather

than in the manufacture of TFT-LCDs in which the substrate is fixed and EBR is performed rectilinearly.

However, the problem of the penetration into the interface of the photoresist

has not been solved.

SUMMARY OF THE INVENTION

An object of the present invention is to solve the above-mentioned problem, and to provide a thinner composition that is capable of effectively removing unwanted photoresist in a short period of time not only from the substrate used in the manufacture of display devices but also from the large-sized glass substrate

used in the manufacture of organic EL displays, without regard to the particular

photoresist used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To attain the object, the present invention provides a thinner composition for

removing photoresist, including a) alkylene glycol monoalkyl ether acetate, b) alkyl lactate, and c) y-butyrolactone.

Preferably, the thinner composition may include a) 40 to 90 parts by weight of propylene glycol monoalkyl ether acetate, b) 5 to 30 parts by weight of alkyl lactate, and c) 1 to 30 parts by weight of y-butyrolactone. Also, the thinner composition of the present invention may further include at least one compound selected from the group consisting of d) a fluorinated acrylic copolymer and e) a polyethylene oxide-based condensate.

Hereunder is given a detailed description of the present invention. The thinner composition for removing photoresist in accordance with the present invention is capable of effectively removing unwanted photoresist from the edge and back of a glass substrate used in a photolithographic process of, for example, the manufacture of liquid crystal displays and organic EL displays, and from the edge and back of a wafer used in the manufacture of semiconductor devices, in a short period of time. The thinner composition of the present invention

is applicable to a variety of processes and is capable of reducing cost, simplifying manufacturing processes, and improving production yield. Preferably, the thinner composition of the present invention can be used in the photolithographic process for organic EL displays or LCDs.

The thinner composition for removing photoresist according to the present invention includes a) alkylene glycol monoalkyl ether acetate, b) alkyl lactate, and c) y-butyrolactone.

Each of the alkylene glycol monoalkyl ether acetate, alkyl lactate, and y- butyrolactone used in the thinner composition of the present invention may be highly pure, i.e., of the semiconductor grade. For VLSI grade, it is preferable to use those filtered to the scale of 0.1μm.

In the thinner composition of the present invention, the a) alkylene glycol monoalkyl ether acetate may be one having 1 to 5 carbon atoms in the alkyl group. Specifically, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, etc. may be used alone or in combination. Among them, propylene glycol monomethyl ether acetate (PGMEA) is more preferable because it has outstanding solubility for polymers.

Preferably, the alkylene glycol monoalkyl ether acetate is comprised at 40 to 90 parts by weight per 100 parts by weight of the entire composition. If the content of the alkylene glycol monoalkyl ether acetate is below 40 parts by weight or exceeds 90 parts by weight, EBR capacity may become insufficient.

Also preferably, the b) alkyl lactate used in the thinner composition of the present invention is one having 1 to 4 carbon atoms in the alkyl group. Specifically,

at least one selected from the group consisting of methyl lactate, ethyl lactate, propyl lactate, and butyl lactate may be used. Among them, ethyl lactate is more preferable. Preferably, the alkyl lactate is used at 5 to 30 parts by weight per 100 parts by weight of the entire composition. If the content of the alkyl lactate is below 5 parts by weight, EBR capacity is insufficient. In contrast, if it exceeds 30 parts by weight, the EBR profile becomes poor.

The y-butyrolactone is used at 1 to 30 parts by weight per 100 parts by weight of the entire composition. If the content of the y-butyrolactone is below 1 part by weight, EBR capacity is insufficient. In contrast, if it exceeds 30 parts by

weight, residues may remain due to insufficient evaporation.

The thinner composition of the present invention may further include at least one compound selected from the group consisting of d) a fluorinated acrylic copolymer and e) a polyethylene oxide-based condensate.

For the d) fluorinated acrylic copolymer, one having superior solubility in water and various solvents, for example Megafac R-08 that is commercially available from Dainippon Ink and Chemicals, can be used. Preferably, the fluorinated acrylic copolymer is included at 0.001 to 1 part by weight per 100 parts by weight of the entire composition. If the content of the fluorinated acrylic copolymer is below 0.001 parts by weight, dissolving power for photoresist decreases significantly. In contrast, if it exceeds 1 part by weight, severe foaming may cause malfunction of the liquid level sensor, although superior removal capacity can be obtained as the dynamic surface tension at the interface is lowered.

For the fluorinated acrylic copolymer, one having a weight average molecular weight ranging from 3000 to 10,000, and preferably one having a flash point (measured by open-cup test) of 200⁰C, a specific gravity of 1.10 g/mL (25°C), a viscosity of 2100 cst (2O⁰C), and a surface tension in ethyl lactate of 24.0 mN/m (Wilhermy method), is used while diluted in ethyl lactate.

The e) polyethylene oxide-based condensate functions as a nonionic

surfactant. Specifically, a condensation product of alkylphenol having linear or branched C₆-Ci₂ alkyl groups and 5 to 25 moles of ethylene oxide per 1 mole of the alkylphenol is preferable. The alkyl substituent of the alkylphenol may be derived from propylene, diisobutylene, octene, or nonene. Examples of such compound are nonylphenol obtained from condensation of about 9.5 moles of ethylene oxide with 1 mole of phenol, dodecylphenol obtained from condensation of about 12 moles of ethylene oxide with 1 mole of phenol, diisooctylphenol obtained from condensation of about 15 moles of ethylene oxide with 1 mole of phenol, and so forth. With superior solubility in water and various solvents, these compounds reduce property differences of thinner and photoresist at the interface. For commercially available products, Dongnam Chemical Industries' Nonionic Monopol

series can be used.

Preferably, the polyethylene oxide-based condensate, which is used as a nonionic surfactant, is included at 0.001 to 0.1 parts by weight per 100 parts by weight of the entire composition. If its content is below 0.001 parts by weight, volatility and cleansing power of the thinner at the edge of the substrate worsen

notably. In contrast, if it exceeds 0.1 parts by weight, foaming occurs severely.

The method for preparing the photoresist thinner composition of the present invention is not particularly limited. It can be prepared by the conventional method of mixing the aforementioned components. After photoresist has been coated on a

substrate, unwanted photoresist at the edge and back of the substrate is removed by dripping the thinner composition or by spraying it through a nozzle. The amount of the thinner composition of the present invention to be dripped or sprayed may be adjusted depending on the particular photosensitive resin used and the film thickness. Preferably, the dripping or spraying rate is in the range of 5 to 100 cc/min. After the thinner composition has been sprayed, a microcircuit pattern may

be obtained by a photolithographic process.

Hereinafter, the present invention is described in further detail through examples. However, the following examples are only for the understanding of the present invention and the present invention is not limited to or by them. Examples

The substrate samples used in the examples were prepared as follows. A silicon oxide substrate 8 inches in diameter was cleansed in two separate baths containing hydrogen peroxide and sulfuric acid, respectively (immersed in each bath

for 5 minutes), and then rinsed with ultrapure water. This process was performed

in a specially-designed cleansing apparatus. Subsequently, the substrate was dried using a spin drier (SRD 1800-6, VERTEQ). Then, photoresist was coated on the substrate to a predetermined thickness. The coating of the photoresist was performed using a spin coater (EBR TRACK, Korea Semiconductor System). The

spin coating was performed by dripping 10 cc of the photoresist at the center of the

stationary substrate. Next, the photoresist was dispersed for 3 seconds at 300 rpm using the spin coater. Subsequently, the substrate was spun at a rate of about 1000 to 2000 rpm to form a predetermined thickness. The spinning was performed for about 20 to 30 seconds.

Examples 1 to 10 and Comparative Examples 1 to 5

The thinner compositions of Examples 1 to 10 and Comparative Examples 1 to 5 were prepared with the compositions and contents given in Table 1 below. [Table 1 ]

Note)

1. PGME: propylene glycol monomethyl ether

2. PGMEA: propylene glycol monomethyl ether acetate

3. nBA: n-butyl acetate

4. EL: ethyl lactate

5. GBL: y-butyrolactone

6. Sur.1 : polyethylene oxide-based condensate (Nonionic Monopol series, Dongnam Chemical Industries)

7. Sur.2: fluorinated acrylic copolymer (Megafac R-08, Dainippon Ink and

Chemicals)

Removal of unwanted photoresist

Photoresist was coated on an 8-inch silicon oxide substrate and the efficiency of removal of unwanted photoresist at the edge was tested with each thinner composition of Examples 1 to 10 and Comparative Examples 1 to 5 (edge bead removal test, hereunder referred to as EBR test). The same spin coater that was used in the coating of the photoresist on the substrate was used for the EBR

test.

Each thinner composition presented in Table 1 was sprayed on the photoresist-coated substrate through the EBR nozzle to remove the photoresist under the condition given in Table 2 below. Each thinner composition was supplied from a pressurized container equipped with a pressure gauge. The pressure inside

the container was 1.0 kgf and the flow rate of the thinner composition was 10 to 20

cc/min.

The EBR test result is given in Table 3 below. [Table 2]

[Table 3]

In Table 3, "©" means a good EBR line uniformity after EBR of the photoresist, "0" means an EBR line uniformity of 80% or better, "Δ" means line uniformity of 50% or better, and "x" means an EBR line uniformity of 20% or better with tailing of the photoresist at the edge.

As seen in Table 3, all the thinner compositions of the present invention showed superior EBR capacity (EBR line uniformity). In contrast, all the thinner compositions of Comparative Examples 1 to 5 showed disappointing results.

As is apparent from the above description, the thinner composition for removing photoresist in accordance with the present invention is capable of effectively removing unwanted photoresist at the edge and back of large-sized glass substrates for organic EL displays, as well as those used for manufacturing display devices, in a short period of time regardless of the particular photoresist used.

While the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that various

modifications and substitutions can be made thereto without departing from the spirit

and scope of the present invention as set forth in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A thinner composition for removing photoresist, comprising: a) propylene glycol monoalkyl ether acetate;

b) alkyl lactate; and c) y-butyrolactone.

2. The thinner composition of Claim 1 , which comprises:

a) 40 to 90 parts by weight of propylene glycol monoalkyl ether acetate; b) 5 to 30 parts by weight of alkyl lactate; and c) 1 to 30 parts by weight of y-butyrolactone.

3. The thinner composition of Claim 1 , wherein the propylene glycol monoalkyl ether acetate is at least one selected from the group consisting of

propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, and propylene glycol monobutyl ether acetate.

4. The thinner composition of Claim 1 , wherein the alkyl lactate is at least one selected from the group consisting of methyl lactate, ethyl lactate, propyl lactate, and butyl lactate.

5. The thinner composition of Claim 1 , which further comprises d) 0.001 to 1 part by weight of a polyethylene oxide-based condensate.

6. The thinner composition of Claim 1 , which further comprises e) 0.001 to 0.1 parts by weight of a fluorinated acrylic copolymer.

7. The thinner composition of Claim 1 , which further comprises d) 0.001 to 1 part by weight of a polyethylene oxide-based condensate and e) 0.001 to 0.1 parts by weight of a fluorinated acrylic copolymer.

8. The thinner composition of Claim 5 or Claim 7, wherein the polyethylene oxide-based condensate is a condensation product of alkylphenol having linear or

branched C₆-C₁₂ alkyl groups and 5 to 25 moles of ethylene oxide per 1 mole of the

alkylphenol.

9. The thinner composition of Claim 6 or Claim 7, wherein the fluorinated

acrylic copolymer has a weight average molecular weight ranging from 3000 to

10,000.