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
1998-12-01
2001-10-09
Baxter, Janet (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
C430S910000, C526S271000
Reexamination Certificate
active
06300036
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to photosensitive polymers used in chemically amplified photoresist compositions, and photoresist compositions including such polymers.
2. Description of the Related Art
With increasing integration of semiconductor devices, there is a heightened need in photolithography for photoresists that form a fine pattern line of less than 0.25 &mgr;m. Photolithography technology has now been developed that can be used with an ArF excimer laser (e.g., &lgr;=193 nm) to fabricate semiconductor devices having more than a 1 gigabit capacity. This technology is intended to replace the conventional KrF excimer lasers which expose photoresist films using deep ultraviolet rays (&lgr;=248 nm). It is therefore desirable to develop new chemically amplified photoresist compositions that produce a fine pattern line of less than 0.25 &mgr;m when exposed using an ArF excimer laser.
Chemically amplified photoresist compositions for use with an ArF excimer laser should possess the following qualities:
(1) excellent transmittance in the range of 193 nm;
(2) excellent thermal characteristics, such as for example, a high glass transition temperature (Tg), and a thermal decomposition temperature (Td) higher than its Tg so that the photoresist can be baked to a temperature that is above the (Tg) before being exposed in order to vaporize unwanted organic solvents and to make the photoresist film hard, without causing the photoresist to decompose;
(3) excellent adhesion to film materials;
(4) excellent resistance to dry etching; and
(5) the capability of being developed using conventional alkaline developers, such as 2.38 weight percent (wt %) tetramethylammonium hydroxide(TMAH).
One example of a polymer that has been reported to possess the above properties is the photosensitive terpolymer poly(MMA-tBMA-MAA) which is represented by the following chemical formula:
However, poly(MMA-tBMA-MAA) is not an ideal polymer for making photoresist compositions because it has a very weak resistance to dry etching, it has weak adhesive properties, and a special developer is needed. Methacrylate polymers are generally used in the photoresist resist materials for photolithography processes that use an ArF excimer laser. However, such polymers have a very weak resistance to dry etching. To increase resistance to dry etching, a polymer having a backbone composed of an alicyclic compound such as an isobornyl group, an adamantyl group, or a tricyclodecanyl group is used. These conventional polymers, however still exhibit weak resistance to dry etching. They also have inadequate adhesion characteristics, which means that a resist layer formed using the polymer may lift from the underlying layer, thus forming a photoresist pattern that is not sharp enough. These polymers also require special developers.
SUMMARY OF THE INVENTION
An object of the present invention is to provide photosensitive polymers for use in chemically amplified photoresists which may be exposed using ArF lasers. The photoresists must have strong resistance to dry etching, possess excellent adhesion to film materials, and be capable of being developed using conventional developers known to those skilled in the art.
It is another objective of the present invention to provide photoresist compositions containing these photosensitive polymers that are suitable for use in photolithography processes that use the ArF excimer laser.
It is a further object of the invention to provide chemically amplified photoresists containing such photosensitive polymers.
These and other objects of the present invention are provided by photosensitive polymers for use in chemically amplified photoresists. In a first embodiment, the invention provides copolymers for use in chemically amplified photoresists. The copolymers are of the general chemical formula(CFI):
In the above (CFI), R
1
is selected from the group including hydrogen and C
1
to C
20
aliphatic hydrocarbons; and n represents an integer. In a preferred embodiment, R
1
is one selected from the group including methyl, ethyl, n-butyl, and cyclohexyl. In another preferred embodiment R
1
is selected from the group including C
7
to C
20
alicyclic aliphatic hydrocarbons including adamantyl, norbornyl, or isobornyl groups. The copolymers of the present invention have a weight average molecular weight ranging from about 3,000 to about 100,000.
In another aspect, the invention provides a photoresist composition including terpolymers and photo acid generators. The terpolymers are of the chemical formula (CFII):
In the above (CFII), R
1
is selected from the group including hydrogen and C
1
to C
20
aliphatic hydrocarbons; R
2
is hydrogen or a methyl group; R
3
is a t-butyl or tetrahydropyranyl group; and n and m are integers. The ratio of n/(m+n) is from about 0.1 to about 0.5. In a preferred embodiment, R
1
is one selected from the group including methyl, ethyl, n-butyl, and cyclohexyl. In an alternative embodiment R
1
is selected from the group including C
7
to C
20
alicyclic aliphatic hydrocarbons including adamantyl, norbornyl, or isobornyl groups. The terpolymers have a weight average molecular weight ranging from about 3,000 to about 200,000.
Photo acid generators (PAGs) are present in a photoresist composition in amounts ranging from about 1.0 wt % to 20.0 wt % based upon the weight of the terpolymers. In a preferred embodiment, the photo acid generators are one selected from the group including triarylsufonium salts, diaryliodonium salts, sulfonates and mixtures thereof. In another preferred embodiment, the triarylsulfonium salt is one selected from the group including triphenylsulfonium triflate, triphenylsulfonium antimonate, 2,6-dinitrobenzyl sulfonates, and pyrogallol tris(alkylsulfonate). The diaryliodonium salt is one selected from the group including diphenyliodonium triflate, diphenyliodonium antimonate, methoxydiphenyliodonium triflate, di-t-butyldiphenyliodonium triflate, or mixtures thereof.
REFERENCES:
patent: 3280080 (1966-10-01), Potter et al.
patent: 5372912 (1994-12-01), Allen et al.
patent: 5843624 (1998-12-01), Houlihan et al.
patent: 5876899 (1999-03-01), Szmanda et al.
patent: 5879857 (1999-03-01), Chandross et al.
patent: 6103450 (2000-08-01), Choi
patent: 6103845 (2000-06-01), Choi et al.
patent: 6171754 (2001-01-01), Choi et al.
patent: 10130340 (1998-05-01), None
Sang-Jun Choi et al. “Novel Single-Layer Chemically Amplified Resist for 193-NM Lithography”, SPIE vol. 3049, pp. 104-112, Jul. 1997.
Choi Sang-jun
Jung Dong-Won
Kang Yool
Park Chun-geun
Baxter Janet
Clarke Yvette M.
Jones Volentine, P.L.L.C.
Samsung Electronics Co,. Ltd.
LandOfFree
Photosensitive polymers and chemically amplified 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 Photosensitive polymers and chemically amplified photoresist..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photosensitive polymers and chemically amplified photoresist... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2606157