Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-07-21
2002-09-10
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S258000, C526S259000, C526S265000, C526S271000, C526S318000, C526S318200, C526S318300, C526S320000, C526S321000, C526S323200, C430S270100
Reexamination Certificate
active
06448352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to novel photoresist monomers, polymers formed therefrom, and photoresist compositions containing the same. In particular, the present invention is directed to a bicyclic photoresist monomer compound comprising both amine and protecting group. Moreover, the present invention is also directed to polymers, and a photoresist compositions derived from the bicyclic photoresist monomers, and uses thereof, such as in photolithography processes using a DUV (deep ultraviolet) light source for preparing highly integrated semiconductor devices.
2. Description of the Background Art
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 circumvent the dissolution problem of maleic anhydride, cholesterol type dissolution inhibitors have been added to the photoresist polymers to form a two-component system. However, the increased amount of the dissolution inhibitor [about 30 %(w/w) of the resin) resulted in, among others, poor reappearance, high production cost, poor adhesiveness, and a severe top-loss of the resist in the etching process resulting in a poor pattern formation.
Despite these difficulties, a variety of photoresist polymers with improved etching resistance, adhesiveness and resolution have been developed. Unfortunately, however, most chemically-amplified photoresists currently available have a relatively short post exposure delay (PED) stability. In general, when there is delay between exposure of the photoresist to light and development of the exposed photoresist, acids that are generated on the exposed area are neutralized by amine compounds which may be present in the production atmosphere. Since the pattern formation depends on acids that are generated by the exposure, neutralization of acids by atmospheric amine compounds reduce, prevent or alter a pattern formation, e.g., a T-topping phenomenon may occur where the top portion of the pattern forms a T-shape.
Therefore, there is a need for a photoresist polymer having an excellent etching properties, heat resistance and enhanced PED stability.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel PR polymer having an excellent etching and heat resistance, and an enhanced PED stability. The present inventors have found that a polymer derived from a monomer comprising a bicyclo compound has an excellent etching and heat resistance, and an enhanced PED stability.
Another object of the present invention is to provide PR polymers using the PR monomers described above and a process for preparing the same.
Another object of the present invention is to provide photoresist compositions using 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 a bicyclic PR monomers comprising an amine functional group and an acid labile protecting group. In particular, bicyclic PR monomers of the present invention are compounds of the formula:
where B is selected from the group consisting of moieties of the formula:
R is hydrogen, substituted or non-substituted (C
1
-C
10
) straight or branched chain alkyl, cycloalkyl, alkoxyalkyl, cycloalkoxyalkyl, —COOR′, —(CH
2
)
t
OH, —COO(CH
2
)
t
OH or a moiety of the formula:
each of V and W is independently substituted or non-substituted (C
1
-C
10
) straight or branched chain alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl;
R′ is hydrogen, substituted or non-substituted (C
1
-C
10
) straight or branched chain alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl; R″ is an acid labile protecting group;
each of R
1
-R
12
is independently hydrogen, substituted or non-substituted (C
1
-C
10
) straight or branched chain alkyl, cycloalkyl, alkoxyalkyl, cycloalkoxyalkyl, —CH
2
OH or —CH
2
CH
2
OH;
n is an integer from 1 to 3: and
each of d, m and t is independently an integer from 0 to 5.
The acid labile protecting group is preferably selected from the group consisting of tert-butyl, tetrahydropyran-2-yl, 2-methyl tetrahydropyran-2-yl, tetrahydrofuran-2-yl, 2-methyl tetrahydrofran-2-yl, 1-methoxypropyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl, 1-ethoxy-1-methylethyl, 1-methoxyethyl, 1-ethoxyethyl, tert-butoxyethyl, 1-isobutoxyethyl and 2-acetylmenth-1-en-1-yl.
Particularly preferred bicyclo PR monomers of the present invention are: 2-(1-tert-butoxycarbonylpiperidin-2-yl)ethyl 5-norbornene-2-carboxylate:
2-(1-tert-butoxycarbonylpiperidin-2-yl)ethyl 5-norbomnene-2,3-dicarboxylate:
2-(1-tert-butoxycarbonylpiperidin-2-yl)ethyl, 3-tert-butyl 5-norbornene-2, 3-dicarboxylate:
2,3-di[(1-tert-butoxycarbonylpiperidin-2-yl)ethyl]5-norbomene-2,3-dicarboxylate;
The compound represented by Chemical Formula 1 can be prepared by a variety of methods. In one method of preparing compounds of formula 1, which is particularly useful for compounds 1 where R is hydrogen or substituted or non-substituted (C
1
-C
10
) straight or branched chain alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl, the method comprises:
(al) reacting a diene compound of the formula:
with an acrylate of the formula:
to produce a bicyclic carboxylic acid of the formula:
where R is hydrogen or substituted or non-substituted (C
1
-C
10
) straight or branched chain alkyl, cycloalkyl, alkoxyalkyl or cycloalkoxyalkyl; and n is an integer from 1 to 3;
(b1) reacting the bicyclic carboxylic acid 8 with thionyl chloride (SOCl
2
), preferably in an equal molar amount; and
(c1) reacting the product of step (b 1) with a hydroxy compound of the formula:
to produce the desired compound 1, where B, V and m are those defined above.
In particular, compound 6 is dissolved in an organic solvent and cooled to temperature in the range of from about −35° C. to about −25° C., and compound 7 is slowly added to the mixture. Th
Baik Ki Ho
Jung Jae Chang
Jung Min Ho
Lee Geun Su
Hyundai Electronics Industries Co,. Ltd.
Pezzuto Helen L.
Townsend and Townsend / and Crew LLP
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