Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
1998-04-16
2001-06-05
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S311000, C430S313000, C430S322000
Reexamination Certificate
active
06242164
ABSTRACT:
1. Field of the Invention
The present invention relates to a chemical amplified photoresist, and more particularly, to a method for patterning a chemical amplified photoresist which improves resolution by adjusting a diffusion direction of photo acid.
2. Discussion of the Related Art
A chemical amplified photoresist was published by IBM ten years ago. Using such a chemical amplified photoresist, a DRAM of 1M bit has been manufactured in 1990. LSI manufacturers and research institutions thereof have actively studied the chemical amplified photoresist for application to process. Generally, the chemical amplified photoresist includes a base resin, a light emitting agent, and the like. The chemical amplified photoresist sometimes includes a solubilization-inhibiting agent and a cross-linking agent.
The chemical amplified photoresist is used for the formation of a mask pattern of high resolution in response to catalytic chain reaction caused by diffusion of photo acid generated in the photoresist due to exposure.
A conventional method for patterning a chemical amplified photoresist will be described with reference to the accompanying drawings.
FIG. 1
a
to
FIG. 1
d
are sectional views illustrating a conventional method for patterning a chemical amplified photoresist.
As shown in
FIG. 1
a
, a chemical amplified photoresist
2
is deposited on an etching target layer
1
.
As shown in
FIG. 1
b
, the chemical amplified photoresist
2
is selectively exposed using an exposure mask. In the chemical amplified photoresist
2
, photo acid is produced by exposure process of &lgr;=365 nm, 248 nm, 193 nm.
Subsequently, as shown in
FIG. 1
c
, the photo acid is diffused by post exposure baking (PEB) process of the selectively exposed chemical amplified photoresist
2
. That is, the photo acid is diffused into an exposure region in the chemical amplified photoresist
2
by PEB process. As a result, the photo acid rapidly increases solubility for alkaline aqueous solution of the base resin, for example, solubility for poly hydroxy styrene (PHS).
As shown in
FIG. 1
d
, the chemical amplified photoresist
2
is developed to form a mask pattern layer for etching of the etching target layer
1
.
As described above, the exposure region of the chemical amplified photoresist and its non-exposure region are formed by the exposure and PEB processes, and selectivity ratio of the base resin in the exposure region and the non-exposure region is generated, so that a specific pattern can be achieved by the developing process.
In the chemical amplified photoresist, as the photo acid of a small quantity generated in exposure process is diffused by thermal energy generated in PEB process, catalytic chain reaction of several tens of times to several hundreds of times is induced. The solubility for alkaline aqueous solution of the base resin is increased by such catalytic chain reaction. That is, since enhanced amplified effect of the photoresist can be achieved by the photo acid of a small quantity, the chemical amplified photoresist can be patterned in high resolution.
The conventional method for patterning the chemical amplified photoresist will be described in detail.
The photo acid produced by exposure process is diffused into the photoresist at a distance of about 100-200 nm by PEB process performed under the conditions of temperature between 90° C. and 150° C. and time period of 90-120 sec. Chemical reaction between the base resin of the photoresist and t-butoxy carbonated poly hydroxy styrene (t-BOC) is then induced. As a result, poly hydroxy styrene, CO
2
, isobutane, and photo acid (H
+
) are generated. In the above process, poly hydroxy styrene separated from t-BOC is easily dissolved in alkaline aqueous solution, and a chain of reactions may be induced by the newly generated photo acid (H
+
).
The conventional method for patterning the chemical amplified photoresist has several problems.
When the photo acid is diffused by PEB process, the photo acid is diffused in a horizontal direction as well as a vertical direction. This induces chemical reaction in the non-exposure region. If chemical reaction by diffusion of the photo acid is induced in the non-exposure region, latent image contrast is deteriorated, thereby causing ununiform pattern profile of the chemical amplified photoresist and deteriorating resolution.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method for patterning a chemical amplified photoresist that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method for patterning a chemical amplified photoresist which improves resolution by adjusting diffusion directions of photo acid.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method for patterning a chemical amplified photoresist according to the present invention includes the steps of depositing a chemical amplified photoresist on an etching target layer, selectively exposing the chemical amplified photoresist to generate photo acid on a surface of the exposed chemical amplified photoresist, diffusing the photo acid in only one direction by performing PEB process on condition that electric field is applied to the chemical amplified photoresist, and patterning the chemical amplified photoresist by developing process to remove only a portion where the photo acid is diffused.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5258266 (1993-11-01), Tokui et al.
patent: 5871886 (1999-02-01), Yu et al.
patent: 19825039 (1999-04-01), None
patent: 487 749 A1 (1992-06-01), None
patent: 07086119 (1995-03-01), None
patent: 7-106235 (1995-04-01), None
patent: 7-240365 (1995-09-01), None
American Chemical Society, Washington D.C. 1994, “Introduction to Microlithography”, pp. 212-233.
Choi Yong Kyoo
Kim Byeong Chan
Barreca Nicole
Fleshner & Kim LLP
Huff Mark F.
Hyundai Electronics Industries Co,. Ltd.
LandOfFree
Method for patterning chemical 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 Method for patterning chemical amplified photoresist, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for patterning chemical amplified photoresist will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2438680