Photoresist monomers, polymers thereof, and photoresist...

Details Photoresist monomers, polymers thereof, and photoresist... Photoresist monomers, polymers thereof, and photoresist...

1999-10-15

2001-05-22

Hamilton, Cynthia (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, C526S281000, C526S271000, C562S498000

Reexamination Certificate

active

06235447

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to photoresist monomers, polymers formed therefrom, and photoresist compositions containing same, more specifically, photoresist monomers, polymers and a photoresist compositions suitable for photolithography processes employing DUV (deep ultraviolet) light sources such as KrF (249 mm) and ArF(193 um); EUV; VUV; E-beam; ion-beam; and X-ray.
BACKGROUND OF THE INVENTION
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.
According to the reaction mechanism of such a photoresist, the photoacid generator generates acid when it is illuminated by a light source, and the main chain or branched chain of the resin is reacted with the generated acid to be decomposed or crosslinked. The polarity change of the resin induces solubility differences between the exposed portion and unexposed portion in the developing solution, to form a predetermined pattern.
In the lithography process, resolution depends upon the wavelength of the light source—the shorter the wavelength, the more minute pattern can be formed.
In general, a photoresist (hereinafter, abbreviated to as “PR”) must satisfy various requisites such as excellent etching resistance, heat resistance and adhesiveness, and more preferably, it should be developable in 2.38% aqueous tetramethylammonium hydroxide (TMAH) solution. However, it is very difficult to synthesize a polymer that satisfies all of these requisites. For example, a polymer having a polyacrylate main chain can be easily synthesized, but it has poor etching resistance and has difficulties in the developing process. In order to secure etching resistance, it has been considered to add an alicyclic unit to the main chain. However, in this case, it is very difficult to form a copolymer wherein the main chain is comprised entirely of alicyclic units.
As an attempt to solve the problems described above, Bell Research Center developed a polymer having the following chemical structure, wherein the main chain is substituted with norbornene, acrylate and maleic anhydride units.
However, the above polymer has a problem in that the maleic anhydride moiety (‘A’ portion), which is employed to polymerize alicyclic olefin groups, is readily dissolved in 2.38 wt % aqueous TMAH solution even in an unexposed condition. Thus, in order to inhibit the dissolution of the polymer in the unexposed section, the ratio of ‘Y’ portion having tert-butyl substituent should be increased, but this results in a relative decrease of the ‘Z’ portion (which has a role of increasing adhesiveness to the substrate), and therefore the PR might be easily separated from the substrate at the time of patterning.
In order to solve the 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], reappearance is low and the production cost is high, thereby making the system unsuitable as a PR.
SUMMARY OF THE INVENTION
An object of the present invention is to provide novel PR monomers that can form polymers having excellent etching resistance, adhesiveness and photosensitivity, and can be manufactured on a large scale at a low production cost, and a process for preparing the monomers.
Another object of the present invention is to provide PR polymers having excellent etching resistance, adhesiveness and photosensitivity, 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 element produced by using the photoresist composition.
In order to achieve these objects, the present invention provides a monomer represented by following Chemical Formula 1:
wherein, X
1
and X
2
individually represent CH
2
, CH
2
CH
2
, oxygen or sulfur; Y represents CH
2
or oxygen; R
1
represents H or CH
3
, R′ and R″ individually represent substituted or non-substituted (C
0
-C
3
) alkyl, and i is an integer from 0 to 3.
In order to achieve other technical objects, copolymers are provided comprising said monomer of Chemical Formula 1. The most preferred copolymers are represented by the following Chemical Formula 6:
wherein X
1
and X
2
individually represent CH
2
, CH
2
CH
2
, oxygen or sulfur; Y represents CH
2
or oxygen; W
1
and W
2
individually represent CH
2
, CH
2
CH
2
or oxygen; R
1
, R
2
and R
3
individually represent H or CH
3
; R
4
represents an acid labile protective group; R′ and R″ individually represent substituted or non-substituted (C
0
-C
3
) alkyl; i and j individually represent integers from 0 to 3; and a, b, c and d represent the number of repeating units derived from each monomer.
In addition, a novel photoresist composition is provided comprising the copolymer as described above, a photoacid generator and a conventional organic solvent.
DETAILED DESCRIPTION OF THE INVENTION
Synthesis of Novel Photoresist Monomers
The present inventors have found that a bicyclic derivative containing a hydroxyl group enhances adhesiveness and that a bicyclic derivative containing carboxylic group(s) contributes enhancement of photosensitivity in a photoresist resin (also referred to herein as a copolymer), and have prepared novel monomers of following Chemical Formula 1:
wherein, X
1
and X
2
individually represent CH
2
, CH
2
CH
2
, oxygen or sulfur; Y represents CH
2
or oxygen; R
1
represents H or CH
3
, R′ and R″ individually represent substituted or non-substituted(C
0
-C
3
)alkyl and i is an integer from 0 to 3.
The compound of Chemical Formula 1 provides several advantages as a monomer in a photoresist polymer:
1) it provides excellent adhesiveness to the substrate, as it has three hydroxyl groups per mole;
2) since it also has a carboxyl group, it provides excellent photosensitivity;
3) it does not have an offensive odor; and
4) it can be manufactured on a large scale at a low production cost, because it can be simply synthesized by recrystallization, without complicated separating means such as distillation or column chromatography.
The novel monomer (Chemical Formula 1) according to the present invention can be prepared by (1) dissolving in an organic reaction solvent, a compound of Chemical Formula 2:
<Chemical Formula 2>
HO—R′—Y—R″—OH
wherein Y represents CH
2
or oxygen; R′ and R″ individually represent substituted or non-substituted (C
0
-C
3
) alkyl;
(2) reacting therewith in the presence of an acid catalyst, or under basic conditions, a compound of Chemical Formula 3:
wherein X
1
and X
2
individually represent CH
2
, CH
2
CH
2
, oxygen or sulfur; R
1
represents H or CH
3
, and i is an integer from 0 to 3.
(3) distilling off the organic reaction solvent and neutralizing the resulting residue;
(4) extracting the organic layer from the neutralized residue and distilling off the organic solvent; and
(5) crystallizing the monomer from the resultant residue in an organic crystallization solvent such as benzene.
The compound of Chemical Formula 2 is preferably used in an amount equal to 2 molar equivalents or more. The compounds represented by Chemical Formula 2 include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and diethylene glycol; and the compounds represented by Chemical Formula 3 include 5-norbornene-2,3-dicarboxylic anhydride, methyl-5-norbornene-2,3-dicarboxylic anhydride and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride. As the organic solvent, tetrahydrofuran, dimethylformamide, dioxane, benzene, toluene, or the like may be used.
Since the novel monomers synthesized according to the present invention have both hydroxyl group(s) and car

Affiliated with

Also associated with

Rating

Photoresist monomers, polymers thereof, and photoresist... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Photoresist monomers, polymers thereof, and photoresist..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoresist monomers, polymers thereof, and photoresist... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2564635