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
2000-06-16
2003-06-10
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
C430S311000, C430S325000, C430S905000, C430S921000
Reexamination Certificate
active
06576394
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a chemically amplified, negative-acting, radiation-sensitive photoresist composition and to a method for producing microelectronic devices using such a photoresist. The photoresists of the present invention comprise a phenolic film-forming binder resin having ring bonded hydroxyl groups, a combination of at least two chemically dissimilar cross linking agents, and a compound that generates acid upon exposure to imaging radiation (a photoacid generator).
Photoresist compositions are used in microlithographic processes for making miniaturized electronic components such as in the fabrication of computer chips and integrated circuits. Generally, in these processes, a thin film of a photoresist composition is first applied to a substrate material, such as silicon wafers used for making integrated circuits. The coated substrate is then baked to evaporate solvent in the photoresist composition and to fix the coating onto the substrate. The baked, coated surface of the substrate is next subjected to an image-wise exposure to imaging radiation.
This radiation exposure causes a chemical transformation in the exposed areas of the coated surface. Visible light, ultraviolet (UV) light, electron beam and X-ray radiant energy are imaging radiation types commonly used today in microlithographic processes. After this image-wise exposure, the coated substrate is treated with a developer solution to dissolve and remove either the radiation-exposed or the unexposed areas of the coated surface of the substrate.
There are two types of photoresist compositions, negative-working and positive-working. When negative-working photoresist compositions are exposed image-wise to radiation, the areas of the resist composition exposed to the radiation become less soluble to a developer solution (e.g. a cross-linking reaction occurs) while the unexposed areas of the photoresist coating remain relatively soluble to such a solution. Thus, treatment of an exposed negative-working resist with a developer causes removal of the non-exposed areas of the photoresist coating and the creation of a negative image in the coating, thereby uncovering a desired portion of the underlying substrate surface on which the photoresist composition was deposited.
The use of a negative-working, acid-sensitive photoresist composition is known in the prior art. Most of such prior art photoresist compositions use a crosslinking agent that reacts with the polymeric binder resin to form an insoluble film comprising a higher molecular weight polymer.
SUMMARY OF THE INVENTION
The present invention relates to a chemically-amplified, negative-acting, radiation-sensitive photoresist composition that is developable in an alkaline medium, the photoresist comprising:
a) a phenolic film-forming polymeric binder resin having ring bonded hydroxyl groups;
b) a photoacid generator that forms an acid upon exposure to radiation, in an amount sufficient to initiate crosslinking of the film-forming binder resin;
c) a crosslinking agent that forms a carbonium ion upon exposure to the acid from step b) generated by exposure to radiation, and which comprises an etherified aminoplast polymer or oligomer;
d) a second crosslinking agent that forms a carbonium ion upon exposure to the acid from step b) generated by exposure to radiation, and which comprises either: 1) a hydroxy substituted- or 2) a hydroxy C
1
-C
4
alkyl substituted-C
1
-C
12
alkyl phenol, wherein the total amount of the crosslinking agents from steps c) and d) is an effective crosslinking amount; and
e) a photoresist solvent.
The present invention also relates to a process for producing a microelectronic device, such as a semiconductor, the process comprising:
a) providing a negative-acting photoresist composition comprising:
1) a phenolic film-forming polymeric binder resin having ring bonded hydroxyl groups;
2) a photoacid generator that forms an acid upon exposure to radiation, in an amount sufficient to initiate crosslinking of the film-forming binder resin from step 1);
3) a crosslinking agent that forms a carbonium ion upon exposure to the acid from step 2) generated by exposure to radiation, and which comprises an etherified aminoplast polymer or oligomer;
4) a second crosslinking agent that forms a carbonium ion upon exposure to the acid from step 2) generated by exposure to radiation, and which comprises either: a hydroxy substituted- or a hydroxy C
1
-C
4
alkyl substituted-C
1
-C
12
alkyl phenol, wherein the total amount of the crosslinking agents from steps 3) and 4) is an effective crosslinking amount; and
5) a photoresist solvent.
b) coating the photoresist composition from step a) onto the surface of a suitable substrate;
c) heat treating the coated substrate from step b) until substantially all of the photoresist solvent is removed from the photoresist composition;
d) imagewise exposing the coated photoresist composition from step c) to imaging radiation;
e) heating the substrate after the exposure in step d) and
f) removing the unexposed areas of the coated photoresist composition from step d) with a developer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The compositions of the present invention comprise chemically amplified, negative-acting photoresists sensitive to imaging radiation such as electron beams, ion beams, ultraviolet light or x-rays. These compositions are chemically amplified by having one photon or energetic particle absorbed by the acid generator, which provides one acid molecule that can subsequently catalyze many crosslinking reactions. The generation of acid from the radiation sensitive photoacid generator does not require heat, and exposure to imaging radiation is sufficient.
The phenolic film-forming polymeric binder resin utilized in the photoresist compositions of the present invention is preferably a hydroxyaromatic polymer that is soluble in an alkaline medium such as an aqueous alkaline developer, but insoluble in water. These binder resins are capable of undergoing crosslinking in the presence of a crosslinking agent. The binder resins are chosen so that the photoresist compositions of the present invention are soluble in alkaline medium, such as an aqueous alkaline developer, before being crosslinked. However, these compositions then become insoluble in such alkaline medium after crosslinking.
Preferred binder resins may comprise a novolak, preferably derived from a substituted phenol such as ortho-cresol; meta-cresol; para-cresol; 2,4-xylenol; 2,5-xylenol; 3,4-xylenol, 3,5-xylenol, thymol and mixtures thereof, that has been condensed with an aldehyde such as formaldehyde. The binder resin may also comprise a poly(vinyl phenol) such as a poly(para-hydroxystyrene); a poly(para-hydroxy-alpha-methylstyrene; a copolymer of para-hydroxystyrene or para-hydroxy-alpha-methylstyrene and styrene, acetoxystyrene or acrylic acid and/or methacrylic acid; a hydroxyphenylalkyl carbinol homopolymer; or a novolak/poly(vinyl phenol) copolymer.
The etherified aminoplast crosslinking agent comprises an organic oligomer or polymer that provides a carbonium ion upon and serves to crosslink the film-forming binder resin in the presence of an acid generated by radiation, preferably imaging radiation. This renders the binder resin insoluble in an alkaline medium, in the exposed areas. Such crosslinking agents may be prepared from a variety of aminoplasts in combination with a compound or low molecular weight polymer containing a plurality of hydroxyl, carboxyl, amide or imide groups. Preferred amino oligomers or polymers are aminoplasts obtained by the reaction of an amine, such as urea, melamine, or glycolurea with an aldehyde, such as formaldehyde. Such suitable aminoplasts include urea-formaldehyde, melamine-formaldehyde, benzoguanamine-formaldehyde, and gylcoluril-formaldehyde resins, and combinations of any of these. A particularly preferred aminoplast is hexa(methoxymethyl) melamine oligomer.
The hydroxy-substituted alkyl phenol crosslinking agent comprises an organic polymer that provides a carbonium ion a
Dammel Ralph R.
Lu Ping-Hung
Xu Pingyong
Ashton Rosemary
Clariant Finance (BVI) Limited
Kass Alan P.
Sayko, Jr. Andrew F.
LandOfFree
Negative-acting chemically amplified photoresist composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Negative-acting chemically amplified photoresist composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Negative-acting chemically amplified photoresist composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3153083