CN1290881C - Photosensitive polymer containing adamantyl alkyl vinyl ether and photoresist composition containing the same - Google Patents

Abstract

Photosensitive composition comprising copolymer containing adamantyl alkyl vinyl etherPolymers, and photoresist compositions containing the photosensitive polymers. For example, a photopolymer comprising a copolymer having the general formula: wherein x is an integer of 1 to 4, R1 is a hydrogen atom or a methyl group, R₂Is acid labile C₄～C₂₀The hydrocarbyl group of is 0.1 to 0.4 in terms of p/(p + q + r), 0.1 to 0.5 in terms of q/(p + q + r), and 0.1 to 0.4 in terms of r/(p + q + r).

Description

Photosensitive polymer containing adamantyl alkyl vinyl ether and photoresist composition containing the same

Cross References to Related Applications

This is a continuation-in-part of and claims priority from US nonprovisional patent application 09/764,150, filed January 19, 2001 (ie, the '150 application), which is hereby incorporated by reference. In addition, priority is claimed to Korean Patent Application No. 2002-34998 filed on June 21, 2002, which is hereby incorporated by reference.

The '150 application is a continuation-in-part of US Nonprovisional Patent Application 09/576,053 filed May 23, 2000, now US Patent 6,517,990. In addition, the 150' application claims priority to US Provisional Patent Application 60/198761, filed April 21, 2000, and claims priority to Korean Patent Application 00-2489, filed January 19, 2000, claiming April 19, 2000 Priority of Korean Patent Application 00-20603.

field of invention

The invention relates to a photosensitive polymer and a chemically amplified photoresist composition. More particularly, the present invention relates to photosensitive polymers comprising adamantyl alkyl vinyl ether copolymers, and photoresist compositions comprising the polymers.

Background technique

As semiconductor devices become more highly integrated, photolithography methods used in manufacturing such devices must be capable of forming fine patterns. For example, patterns with a size of 0.2 μm or less are required for semiconductor memory devices with a capacity exceeding 1 Gbyte. Therefore, the application of conventional photoresist materials is limited because they are used with KrF excimer lasers at a wavelength of 248 nm, which is too large for forming ultrafine patterns. A new photoresist material was therefore proposed for use with ArF excimer lasers. This is because the wavelength of the ArF excimer laser is 193 nm, which is smaller than that of the KrF excimer laser.

Photoresist materials currently designed for use with ArF excimer lasers suffer from several disadvantages compared to conventional photoresist materials. The most common of these problems are low light transmission and poor dry etch resistance.

Typically acryl- or (meth)acryl-based polymers are used, well known as ArF photoresist materials. Representative examples of such polymers include poly(methacrylate) based polymeric materials. But such polymers also have the possible disadvantage of poor dry etch resistance. The selectivity of these materials is generally too low to allow dry etching processes using plasma gases.

Therefore, in an effort to enhance dry etch resistance, an alicyclic compound containing strong dry etch resistance, such as isobornyl, adamantyl or decanyl, can be introduced into the polymer on the master chain. However, since only a small portion of the polymer is occupied by cycloaliphatic compounds, the dry etch resistance is still weak. Also, since the alicyclic compound is hydrophobic, if such alicyclic compound is retained in the polymer, the adhesion to the underlying material of the photoresist layer obtained from the polymer becomes poor.

As another conventional polymer, alternating copolymers of cyclic olefin-maleic anhydride (COMA) are proposed. Although the production costs of the raw materials required to produce copolymers such as the COMA system are inexpensive, the yield of the polymer is significantly reduced. Moreover, the light transmittance of the polymer in the short wavelength region such as 193nm is very low. In addition, since such polymers have alicyclic groups on their main chains, they are highly hydrophobic, and as a result their adhesive properties are very poor.

Moreover, due to the structural characteristics of their main chains, these polymers have very high glass transition temperatures of about 200°C or higher. Therefore, it is difficult to perform an annealing process to remove the free volume in the photoresist layer obtained from these polymers. The photoresist layer is thus susceptible to environmental influences. For example, the photoresist pattern has a T-shaped top profile. Also, in the post-exposure to development delay (PED), the photoresist layer shows a decrease in stability to the ambient atmosphere, which causes many problems in many processes using the photoresist layer .

Contents of the invention

The present invention provides photosensitive polymers with favorable adhesion to underlying materials and favorable dry etch resistance which can be produced relatively cheaply.

The present invention also provides a photoresist composition that provides favorable lithographic (lithographic) properties during photolithography using exposure light sources in the short wavelength region, such as 193 nm, and deep ultraviolet region, such as 248 nm.

According to one aspect of the present invention, there is provided a photosensitive polymer comprising a copolymer having the general formula 1:

Wherein x is an integer of 1 to 4, R ₁ is a hydrogen atom or a methyl group, R ₂ is an acid-labile C ₄ -C ₂₀ hydrocarbon group, p/(p+q+r)=0.1-0.4, q/( p+q+r) = 0.1 to 0.5, and r/(p+q+r) = 0.1 to 0.4. The weight average molecular weight of the photosensitive polymer is 3,000-50,000.

Preferably, R ₂ is tert-butyl, tetrahydropyranyl or 1-ethoxyethyl. _R is an alicyclic hydrocarbon group, examples are 2-methyl-2-norbornyl (norbornyl), 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-ethyl- 2-isobornyl, 8-methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl, 8-ethyl-8-tricyclo[5,2,1,0 ^{2, 6} ] Decyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 2-propyl-2-adamantyl, 2-methyl-2-fenzyl or 2 -Ethyl-2-Fenyl.

According to one aspect of the present invention, there is provided a photosensitive polymer comprising a copolymer having the general formula 2:

Wherein x is an integer from 1 to 4, _R3 is a hydrogen atom or a hydroxyl group, a carboxyl group, a halogen, a nitrile, an alkyl group, an alkoxyl group, a sulfonate, or an acid-labile _C4 - _C20 ester group, p /(p+q+s)=0.1-0.4, q/(p+q+s)=0.3-0.5, and s/(p+q+s)=0.2-0.5. The weight average molecular weight of the photosensitive polymer is 3,000-30,000.

Preferably, R ₃ is t-butyl ester, tetrahydropyranyl ester or 1-ethoxyethyl carboxyl ester. And, R ₃ is 2-methyl-2-norbornyl ester, 2-ethyl-2-norbornyl ester, 2-methyl-2-isobornyl ester, 2-ethyl-2-isobornyl ester, 8 -Methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl ester, 8-ethyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl ester, 2-methyl Ethyl-2-adamantyl ester, 2-ethyl-2-adamantyl ester, 2-propyl-2-adamantyl ester, 2-methyl-2-fenyl ester or 2-ethyl-2-fenyl ester .

According to another aspect of the present invention, there is provided a photosensitive polymer comprising a copolymer having the general formula 3:

Wherein x is an integer of 1 to 4, R ₁ is a hydrogen atom or a methyl group, R ₂ is a C ₄ -C ₂₀ hydrocarbon group, R ₃ is a hydrogen atom or a hydroxyl group, a carboxyl group, a halogen, a nitrile, an alkyl group, an alkoxy group, Sulfonate, or an ester group of C ₄ ~C ₂₀ , at least one of R ₂ and R ₃ is an acid labile group, p/(p+q+r+s)=0.1~0.3, q/(p +q+r+s)=0.2 to 0.5, r/(p+q+r+s)=0.1 to 0.4, and s/(p+q+r+s)=0.1 to 0.3. The weight average molecular weight of the photosensitive polymer is 3,000-30,000.

According to another aspect of the present invention, there is provided a photoresist composition comprising a photosensitive polymer having the general formula 1, 2 or 3 and a photoacid generator (PAG).

Preferably, the PAG is included in an amount of about 1.0 wt % to 15 wt % based on the total weight of the photosensitive polymer. Preferably, the PAG comprises a triarylsulfonium salt, a diaryliodonium salt, a sulfonate salt, or a mixture of at least two such compounds.

The photoresist composition according to one embodiment of the present invention further includes an organic matrix. The content of the organic matrix is about 0.01% to 2.0% by weight based on the amount of PAG. Examples of organic substrates include triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, triethanolamine, and mixtures of at least two such compounds.

The photosensitive polymer of one embodiment of the present invention is obtained by copolymerizing adamantyl alkyl vinyl ether monomer and maleic anhydride, provides good adhesion to underlying materials, and has high dry etching resistance. Moreover, the main chain of the photopolymer is more flexible than the traditional main chain, which helps to lower the glass transition temperature of the photopolymer. Accordingly, the photoresist composition obtained therefrom exhibits favorable lithographic (lithographic) properties when used in a photolithographic process.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Non-limiting exemplary embodiments of the present invention are described in detail.

Example 1

Synthesis of 1-adamantyl ethyl vinyl ether

36 g (0.2 mol) of 1-adamantane ethanol and 72 g (1.0 mol) of ethyl vinyl ether were added to a round bottom flask to be dissolved in 100 mL of tetrahydrofuran, followed by 5 mol% of mercuric acetate. Thereafter, the reaction product was reacted for about 12 hours under reflux conditions.

After completion of the reaction, the resulting product was vacuum distilled to obtain the desired monomer in 50% yield.

Example 2

Synthesis of 1-adamantyl methyl vinyl ether

The same procedure as in Example 1 was carried out except that 1-adamantanemethanol was used instead of 1-adamantaneethanol to obtain the desired monomer in a yield of 40%.

Example 3

synthetic photopolymer

2.0g (10mmol) monomer synthesized in embodiment 1, maleic anhydride of 1.0g (10mmol), 2.4g (10mmol) 2-methyl-2-adamantyl methacrylate and 0.15g (3mol%) Azobisisobutyronitrile (AIBN) was dissolved in 10 g THF and purged with nitrogen. Thereafter, the resulting product was polymerized at about 65°C for about 20 hours.

After the polymerization reaction was complete, the reaction product was slowly precipitated in excess isopropanol (IPA) and filtered. The filtered precipitate was dissolved again in an appropriate amount of TFH, and then reprecipitated in n-hexane. The resulting filtrate was dried for about 24 hours in a vacuum oven maintained at about 50°C to obtain a terpolymer having the above general formula in a yield of 70%.

The resulting product had a weight average molecular weight (Mw) of about 9700 and a polydispersity (Mw/Mn) of 1.7.

Example 4

synthetic photopolymer

2.0g (10mmol) of the monomer synthesized in Example 1, 1.0g (10mmol) of maleic anhydride, 2.2g (10mmol) of 2-methyl-2 adamantyl acrylate and 0.15g (3mol%) of azobis Isobutyronitrile (AIBN) was dissolved in 10g THF, and polymerized in the same manner as in Example 3, to obtain a terpolymer with a yield of 68% having the above general formula.

The product obtained had a weight average molecular weight (Mw) of about 10700 and a polydispersity (Mw/Mn) of 1.9.

Example 5

synthetic photopolymer

2.0g (10mmol) monomer synthesized in embodiment 1, 2.0g (20mmol) maleic anhydride, 2.0g (10mmol) 5-norbornene-2-carboxylate and 3mol% azobisisobutyronitrile ( AIBN) is dissolved in 12g THF, is polymerized in the same manner as embodiment 3, obtains the terpolymer with the above-mentioned general formula that yield is 55%.

The resulting product had a weight average molecular weight (Mw) of about 8600 and a polydispersity (Mw/Mn) of 1.9.

Example 6

synthetic photopolymer

2.0g (10mmol) monomer synthesized in Example 1, 1.5g (15mmol) of maleic anhydride, 0.5g (5mmol) norbornene, 3.5g (15mmol) 2-methyl-2-adamantyl methacrylic acid Ester and 3mol% azobisisobutyronitrile (AIBN) were dissolved in 15g THF, and polymerized in the same manner as in Example 3 to obtain a terpolymer with a yield of 70% having the above general formula.

The resulting product had a weight average molecular weight (Mw) of about 9800 and a polydispersity (Mw/Mn) of 1.8.

Example 7

Preparation of Photoresist Compositions and Flat Panel (Lithographic) Properties

A method for preparing a photoresist composition according to an embodiment of the present invention will now be described.

First, the photosensitive polymer and photoacid generator (PAG) synthesized in Examples 3-6 were dissolved in various forms of solvents such as propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate or cyclohexanone, to Prepare photoresist solution. If necessary, the amine-containing organic matrix is added in an amount of about 0.01 to 2.0 wt%, based on the amount of PAG. Also, in order to adjust the overall dissolution rate of the photoresist, the photoresist composition may further include 5˜25 wt % of a dissolution inhibitor based on the amount of the photosensitive polymer.

Based on the amount of photosensitive polymer, the content of PAG is preferably about 1 to 15 wt%. As the PAG, inorganic onium salts or organic onium salts may be used each alone or in combination of two or more. Examples of PAGs include triarylsulfonium trifluoromethanesulfonate (triflate), diaryliodonium trifluoromethanesulfonate, triarylsulfonium nonaflate (nonaflate), diarylsulfonium nonaflate iodonium, succinimidyl trifluoromethanesulfonic acid (salt), 2,6-dinitrobenzylsulfonate, and the like.

For the flat panel (lithography) process, the photoresist solution was first filtered twice using a 0.2 μm membrane filter to obtain the photoresist composition.

The resulting photoresist composition was processed to obtain a pattern as follows.

First, a bare silicon wafer or a silicon wafer with a bottom layer, such as a silicon oxide layer, a silicon nitride layer or a silicon oxynitride layer, to be patterned thereon is prepared and treated with hexamethyldisilazane (HMDS). After that, the silicon wafer was coated with a photoresist composition to a thickness of about 0.3 μm to form a photoresist layer.

The silicon wafer with the photoresist layer is prebaked at a temperature of 120°C to 140°C for about 60 to 90 seconds to remove the solvent, and then irradiated with different forms of exposure light sources, such as deep UV (KrF or ArF), remote UV (EUV) and E-beam or X-ray. Next, in order to induce a chemical reaction in the exposed portion of the photoresist layer, a post-exposure bake (PEB) is performed at a temperature of 110° C. to 140° C. for about 60 to 90 seconds.

Accordingly, the exposed portion showed a very high solubility to a developer solution containing 2.38 wt% of tetramethylammonium hydroxide (TMAH). Therefore, during development, the exposed portion is well dissolved and removed. In the case of using an ArF excimer laser, a pattern with a line pitch of 120 to 140 nm can be formed at an irradiation dose of about 8 to about 25 mJ/cm ² .

An underlying layer to be patterned, such as a silicon oxide film, is etched by _a special etching gas such as plasma such as halogen or _CxFy gas using the resulting photoresist pattern as a mask. Subsequently, the photoresist pattern remaining on the wafer is removed by ashing and a wet process using a stripper, thereby forming a desired silicon oxide pattern.

Table 1 lists the evaluation results of the lithographic performance of the photoresist composition according to the embodiment of the present invention.

For the evaluation results listed in Table 1, 1 g of each of the photosensitive polymers synthesized in Examples 3 to 6, triphenylsulfonium trifluoromethanesulfonate (TPS), triphenylsulfonium nonafluorobutylsulfonate Sulfonium or a mixture thereof as PAG was dissolved in 8 g of cyclohexane, and 2 mg of triisooctylamine or triisobutylamine as an organic matrix was added thereto for complete dissolution. After that, the photoresist solution was filtered using a 0.2 μm membrane filter to obtain a photoresist composition.

The resulting photoresist composition was coated on a silicon (Si) wafer treated with an antireflection coating to a thickness of about 0.3 μm.

After that, under the temperature and time conditions listed in Table 1, the coated sheet was lightly baked (SB), irradiated using an ArF excimer laser stepper (NA=0.6, σ=0.75), and then Post-exposure bake (PEB) was performed under the temperature and time conditions listed in Table 1. Then, development was performed with a 2.38 wt % tetramethylammonium hydroxide (TMAH) solution for about 60 seconds to form a photoresist pattern. The resolution characteristics of the photoresist patterns are shown in Table 1.

Referring to Table 1, triisooctylamine is used as the organic substrate in Example 7-1, and triisobutylamine is used as the organic substrate in Examples 7-2 to 7-8.

Table 1 Example polymer PAG SB PEB Dose (mJ/cm ² ) Resolution (nm) 7-1 Example 3 (1g) TPS triflate(5mg)TPS nonaflate(10mg) 120℃/90sec 120℃/60sec 15 140 7-2 Example 3 (1g) TPS triflate(5mg)TPS nonaflate(10mg) 120℃/90sec 120℃/60sec 17 120 7-3 Example 3 (1g) TPS triflate(5mg)TPS nonaflate(10mg) 120℃/90sec 130℃/60sec 16 120 7-4 Example 3 (1g) TPS nonaflate (20mg) 120℃/90sec 120℃/90sec 17 120 7-5 Example 3 (1g) TPS triflate(5mg)TPS nonaflate(10mg) 120℃/90sec 120℃/90sec 11 130 7-6 Example 4 (1g) TPS triflate(5mg)TPS nonaflate(10mg) 120℃/90sec 130℃/90sec 13 140 7-7 Example 5 (1g) TPS nonaflate (15mg) 120℃/90sec 130℃/90sec 18 140 7-8 Example 6 (1g) TPS triflate(5mg)TPS nonaflate(10mg) 120℃/90sec 120℃/90sec 16 120

As shown in Table 1, in each embodiment, a clear line spacing pattern of 120-140 nm can be obtained at a dose of 11-17 mJ/cm ² .

The photosensitive polymer according to the embodiment of the present invention can be obtained from a vinyl ether compound that can easily form a cross-linked copolymer with an electron-withdrawing monomer, such as maleic anhydride, during polymerization. In particular, the photosensitive polymer includes adamantyl alkyl vinyl ether as a main component of the main chain. Adamantyl alkyl vinyl ether is a compound having a C ₁ -C ₄ linear methylene group. Photoresist compositions derived from photopolymers exhibit improved dry etch resistance over conventional resist materials and can provide good adhesion to underlying materials.

Meanwhile, the alkyl chain of adamantyl alkyl vinyl ether included in the photosensitive polymer of the present invention can provide flexibility to the photosensitive polymer. Therefore, the main chain of photopolymers is flexible, so these polymers have a relatively low glass transition temperature. Thus, a sufficient heat treatment effect can be achieved to remove the free volume of the photoresist layer obtained from the photopolymer during baking. The photoresist layer thus has enhanced environmental resistance, even in post-exposure-to-develop delay (PED). Therefore, the photoresist composition according to the embodiment of the present invention, when used in a photolithography process, exhibits excellent lithographic performance in lithography, which is advantageous in the manufacture of next-band semiconductor devices.

While the invention has been particularly shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that various forms and modifications may be made therein without departing from the spirit and scope as defined in the appended claims. Variations in details.

Claims (31)

1. A photosensitive polymer comprising a copolymer of the general formula: Wherein x is an integer of 1 to 4, R ₁ is a hydrogen atom or a methyl group, R ₂ is an acid-labile C ₄ -C ₂₀ hydrocarbon group, p/(p+q+r)=0.1-0.4, q/( p+q+r) = 0.1 to 0.5, and r/(p+q+r) = 0.1 to 0.4. 2. The photosensitive polymer of claim 1, wherein the weight average molecular weight of the polymer is 3,000-50,000. 3. The photosensitive polymer of claim 1, wherein R ₂ is tert-butyl, tetrahydropyranyl or 1-ethoxyethyl. 4. The photosensitive polymer according to claim 1, wherein R ₂ is an alicyclic hydrocarbon group. 5. The photosensitive polymer as claimed in claim 4, R ₂ is 2-methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-ethyl Base-2-isobornyl, 8-methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl, 8-ethyl-8-tricyclo[5,2,1,0 ^2,6 ] Decyl, 2-Methyl-2-Adamantyl, 2-Ethyl-2-Adamantyl, 2-Propyl-2-Adamantyl, 2-Methyl-2-Fenyl Or 2-Ethyl-2-Fenyl. 6. A photosensitive polymer comprising a copolymer of the general formula: Wherein x is an integer of 1 to 4, R ₁ is a hydrogen atom or a methyl group, R ₂ is a C ₄ -C ₂₀ hydrocarbon group, R ₃ is a hydrogen atom or a hydroxyl group, a carboxyl group, a halogen, a nitrile, an alkyl group, an alkoxy group, Sulfonate, or an ester group of C ₄ ~C ₂₀ , at least one of R ₂ and R ₃ is an acid labile group, p/(p+q+r+s)=0.1~0.3, q/(p +q+r+s)=0.2-0.5, r/(p+q+r+s)=0.1-0.4 and s/(p+q+r+s)=0.1-0.3. 7. The photosensitive polymer of claim 6, wherein the weight average molecular weight of the polymer is 3,000-30,000. 8. The photosensitive polymer of claim 6, wherein R ₂ is tert-butyl, tetrahydropyranyl or 1-ethoxyethyl. 9. The photosensitive polymer as claimed in claim 6, wherein R is ₂ -methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2- Ethyl-2-isobornyl, 8-methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl, 8-ethyl-8-tricyclo[5,2,1, 0 ^2,6 ]decyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 2-propyl-2-adamantyl, 2-methyl-2-fenzyl base or 2-ethyl-2-fenyl. 10. The photosensitive polymer according to claim 6, wherein _R3 is tert-butyl ester, tetrahydropyranyl ester or 1-ethoxyethyl carboxyl. 11. The photosensitive polymer as claimed in claim 6, wherein R ₃ is 2-methyl-2-norbornyl ester, 2-ethyl-2-norbornyl ester, 2-methyl-2-isobornyl ester, 2- Ethyl-2-isobornyl ester, 8-methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl ester, 8-ethyl-8-tricyclo[5,2,1,0 ^2,6 ] decyl ester, 2-methyl-2-adamantyl ester, 2-ethyl-2-adamantyl ester, 2-propyl-2-adamantyl ester, 2-methyl-2-fenzyl ester or 2-Ethyl-2-fenzyl ester. 12. A photoresist composition comprising: (a) a photosensitive polymer having the following general formula copolymer: Wherein x is an integer of 1 to 4, R ₁ is a hydrogen atom or a methyl group, R ₂ is an acid-labile C ₄ -C ₂₀ hydrocarbon group, p/(p+q+r)=0.1-0.4, q/( p+q+r)=0.1～0.5, and r/(p+q+r)=0.1～0.4; and (b) Photoacid generators. 13. The photoresist composition of claim 12, wherein the weight average molecular weight of the photosensitive polymer is 3,000˜50,000. 14. The photoresist composition of claim 12, wherein R ₂ is tert-butyl, tetrahydropyranyl or 1-ethoxyethyl. 15. The photoresist composition of claim 12, wherein R is ₂ -methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-Ethyl-2-isobornyl, 8-methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl, 8-ethyl-8-tricyclo[5,2, 1,0 ^2,6 ]decyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 2-propyl-2-adamantyl, 2-methyl-2 -Fenyl or 2-ethyl-2-Fenyl. 16. The photoresist composition of claim 12, wherein the photoacid generator is included in an amount of 1.0 wt% to 15 wt% based on the total amount of the photosensitive polymer. 17. The photoresist composition of claim 12, wherein the photoacid generator comprises a triarylsulfonium salt, a diaryliodonium salt, a sulfonate salt, or a mixture of at least two such compounds. 18. The photoresist composition of claim 12, further comprising an organic matrix. 19. The photoresist composition according to claim 18, wherein the content of the organic matrix is 0.01%˜2.0 wt% based on the amount of the photoacid generator. 20. The photoresist composition of claim 18, wherein the organic matrix comprises triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, triethanolamine, and mixtures of at least two such compounds. 21. A photoresist composition comprising: (a) a photosensitive polymer having the following general formula copolymer: Wherein x is an integer of 1 to 4, R ₁ is a hydrogen atom or a methyl group, R ₂ is a C ₄ -C ₂₀ hydrocarbon group, R ₃ is a hydrogen atom or a hydroxyl group, a carboxyl group, a halogen, a nitrile, an alkyl group, an alkoxy group, Sulfonate, or an ester group of C ₄ ~C ₂₀ , at least one of R ₂ and R ₃ is an acid labile group, p/(p+q+r+s)=0.1~0.3, q/(p +q+r+s)=0.2～0.5, r/(p+q+r+s)=0.1～0.4, and s/(p+q+r+s)=0.1～0.3; and (b) Photoacid generators. 22. The photoresist composition of claim 21, wherein the weight average molecular weight of the polymer is 3,000-30,000. 23. The photoresist composition of claim 21, wherein R ₂ is t-butyl, tetrahydropyranyl or 1-ethoxyethyl. 24. The photoresist composition of claim 21, wherein R is ₂ -methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-Ethyl-2-isobornyl, 8-methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl, 8-ethyl-8-tricyclo[5,2, 1,0 ^2,6 ]decyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 2-propyl-2-adamantyl, 2-methyl-2 -Fenyl or 2-ethyl-2-Fenyl. 25. The photoresist composition according to claim 21, wherein R ₃ is tert-butyl ester, tetrahydropyranyl ester or 1-ethoxyethyl carboxyl. 26. The photoresist composition of claim 21, wherein R ₃ is 2-methyl-2-norbornyl ester, 2-ethyl-2-norbornyl ester, 2-methyl-2-isobornyl ester, 2-Ethyl-2-isobornyl ester, 8-methyl-8-tricyclo[5,2,1,0 ^2,6 ]decyl ester, 8-ethyl-8-tricyclo[5,2,1 , 0 ^2,6 ] decyl ester, 2-methyl-2-adamantyl ester, 2-ethyl-2-adamantyl ester, 2-propyl-2-adamantyl ester, 2-methyl-2-fennel ester or 2-ethyl-2-fenzyl ester group. 27. The photoresist composition of claim 21, wherein the photoacid generator is included in an amount of 1.0 wt% to 15 wt%, based on the total amount of the photosensitive polymer. 28. The photoresist composition of claim 21, wherein the photoacid generator comprises a triarylsulfonium salt, a diaryliodonium salt, a sulfonate salt, or a mixture of at least two such compounds. 29. The photoresist composition of claim 21, further comprising an organic matrix. 30. The photoresist composition according to claim 29, wherein the organic matrix is contained in an amount of 0.01% to 2.0 wt% based on the amount of the photoacid generator. 31. The photoresist composition of claim 29, wherein the organic matrix comprises triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, triethanolamine, and mixtures of at least two such compounds.