Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2000-07-21
2002-04-09
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S326000, C430S913000, C430S921000, C560S120000, C526S282000
Reexamination Certificate
active
06368770
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photoresist monomer, polymers derived from the monomer, and photoresist compositions comprising the same. More specifically, the invention relates to a bis(norbornene carboxylate) and a bis(norbornene dicarboxylate) monomers comprising an acetal group, polymers derived from the same, and photoresist compositions comprising the same.
2. Description of the Background Art
Recently, chemical amplification type DUV photoresists have been investigated in order to achieve high sensitivity in minute image formation processes for preparing semiconductor devices. Such photoresists are prepared by blending a photoacid generator and matrix resin polymer having an acid labile group.
In the lithography process, resolution depends upon the wavelength of the light source—the shorter the wavelength, the more minute pattern can be formed.
Recently, chemical amplification type DUV photoresists have been investigated for achieving a high sensitivity in minute image formation processes for preparing semiconductor devices. Such photoresists are typically prepared by blending a photoacid generator and a matrix resin polymer having an acid labile group. The resolution of a lithography process depends, among others, on the wavelength of the light source, i.e., shorter the wavelength, smaller the pattern formation.
In general, a useful photoresist (hereinafter, abbreviated to as “PR”) has a variety of desired characteristics, such as an excellent etching resistance, heat resistance and adhesiveness. Moreover, the photoresist should be easily developable in a readily available developing solution, such as 2.38% aqueous tetramethylammonium hydroxide (TMAH) solution. However, it is very difficult to synthesize a photoresist polymer, especially DUV photoresist, which meets all of these desired characteristics. For example, a polymer having a polyacrylate polymer backbone are readily available, but it has a poor etching resistance and is difficult to develop. In order to increase its etching resistance, several groups have added an alicyclic unit to the polymer backbone. However, photoresist copolymers comprising entirely of an alicyclic polymer backbone is difficult to form.
To solve some of the problems described above, Bell Research Center developed a polymer having the following chemical formula:
where the polymer backbone is substituted with a norbornene, an acrylate and a maleic anhydride unit. Unfortunately, even in the unexposed regions, the maleic anhydride moiety (‘A’ portion) dissolves readily in 2.38 wt % aqueous TMAH solution. Therefore, in order to inhibit the dissolution of the polymer in the unexposed section, the ratio of ‘Y’ portion having tert-butyl substituent must be increased, but this increase results in a relative decrease in the ‘Z’ portion, which is responsible for the adhesiveness of the photoresist polymer. This decrease in the relative amount of the ‘Z’ portion may result in separation of the photoresist from the substrate during a pattern formation.
In order to solve this problem, cholesterol type dissolution inhibitors have been added to the polymer to form a two-component system. However, since the amount of the dissolution inhibitor is very high [about 30% (w/w) of the resin], reproducibility is low and the production cost is high, thereby making the system unsuitable as a PR.
Therefore, there is a need for a photoresist polymer which provides an excellent etching properties, adhesiveness, ease of development, and good pattern formation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide PR polymers having excellent etching resistance, adhesiveness and photosensitivity, and a process for preparing the same.
Specifically, the present invention provides novel PR monomers, in particular, bis(norbornene carboxylate) and bis(norbornene dicarboxylate) compounds, which comprise an acetal protecting group and a process for preparing the same.
Another object of the present invention is to provide photoresist compositions comprising the PR polymers described above, and a process for preparing the same.
Still another object of the present invention is to provide a semiconductor device produced by using the PR composition.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides photoresist monomers of the formula:
where A is hydrogen or —COOR
1
; A′ is hydrogen or —COOR
2
; each of R
1
and R
2
is independently hydrogen or, substituted or non-substituted (C
1
-C
10
) linear of branched alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl; X is substituted or non-substituted (C
1
-C
10
) linear of branched alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl; m is an integer from 1 to 8; and n is an integer from 1 to 3. In the present invention, the compound of formula 1 is named using the following nomenclature: the bis(norbornene carboxylate) group is named first as bis(norbornene carboxylyl) followed by the group containing —O—(X)
m
—O— as a dihydroxy group which is followed by the name diethyl ether. For example, a compound of formula 1 where A=H, m=1, n=1 and X=propyl would be called bis(5-norbornene-2-carboxylyl)-1,3-propanediol diethyl ether.
Thus, the compound of Formula 1 encompasses bis(norbornene carboxylate) of formula 1a and bis(norbornene dicarboxylate) of formula 1b:
Preferably, R
1
and R
2
are selected from the group consisting of hydrogen, methyl, ethyl and tert-butyl. More preferably, R
1
and R
2
are identical.
The following are particularly preferred compounds of formula 1:
The compound of formula 1 can be prepared by reacting a compound of Formula 5:
with a compound of Formula 6:
preferably in an organic solvent, in the presence of an acid catalyst, where A, X, m and n are those defined above. The reaction temperature is typically in the range of from about 10° C. to about 50° C. And the reaction time is generally from about 8 to about 12 hours. After the reaction, removal of the organic solvent typically affords the desired compound of formula 1.
While any non-protic organic solvent can be used in the preparation of compound of formula 1, typically tetrahydrofuran (THF), dimethylformamide, dioxane, benzene, toluene or xylene are used. In addition, it is within the knowledge of one skilled in the art of organic chemistry in selecting an appropriate acid catalyst for the above described method. Such acid catalyst includes any organic and inorganic acids. A preferred acid catalyst includes para-toluenesulfonic acid.
The compound of formula 5 is preferable selected from the group consisting of 5-norbornene-2-carboxylic acid and 5-norbornene-2,3-dicarboxylic acid. And preferably, a compound of formula 6 is selected from a group consisting of 1,4-butanediol divinyl ether, 1,3-propanediol divinyl ether and 1,4-cyclohexane dimethanol divinyl ether.
The present invention also provides photoresist copolymer comprising a compound of formula 1. As used herein, the term “photoresist copolymer comprising a compound” of formula 1 means a photoresist copolymer which is derived from polymerizing the compound of formula 1.
The photoresist copolymer of the present invention can also include a second monomer which is represented by a compound of the formula:
where Y is substituted or non-substituted (C
1
-C
10
) linear or branched alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl; 1 is an integer from 1 to 8, and s is an integer from 1 to 3. Preferably, the second monomer is selected from the group consisting of 2-hydroxyethyl5-norbornene-2-carboxylate or 3-hydroxypropyl 5-norbornene-2-carboxylate.
In addition, the photoresist copolymer of the present invention can also include a third monomer is selected from the group consisting of a compound of the formula:
where each of R, R
3
and R
4
is independently hydrogen or substituted or non-substituted (C
1
-C
10
) linear or branched alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl; and each of t and u is independently an integer from 1 to 3. Preferably, a comp
Baik Ki Ho
Jung Jae Chang
Jung Min Ho
Lee Geun Su
Ashton Rosemary
Hyundai Electronics Industries Co,. Ltd.
Townsend and Townsend / and Crew LLP
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