Method of enhancing photoresist anti-etching ability

Details Method of enhancing photoresist anti-etching ability Method of enhancing photoresist anti-etching ability

2001-05-22

2003-10-14

Duda, Kathleen (Department: 1756)

Radiation imagery chemistry: process, composition, or product th

Imaging affecting physical property of radiation sensitive...

Simultaneous radiation imaging and etching of substrate

C430S296000, C430S313000, C430S328000, C430S942000

Reexamination Certificate

active

06632587

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to method of forming photoresist anti-etching ability, and particularly relates to method for increasing process window and reducing required thickness of photoresist.
2. Description of the Prior Art
For etch process, as
FIG. 1A
shows, photoresist
12
and etched layer
11
are formed on substrate
10
sequentially, pattern of photoresist
12
defines which part of etched layer
11
would be removed by etch process. Obviously, to ensure etched layer
11
and photoresist
12
have same pattern after etch process is finished, pattern of photoresist
11
should not be changed while etch process being performed.
However, photoresist
12
also is removed by practical etch process, especially edge of opening
13
, although removed rate of photoresist
12
usually is obviously smaller than removed rate of etched layer
12
. Thus, after etch process is finished, flowing cases may be happened. As
FIG. 1B
shows, although thickness of photoresist
12
is decreased, pattern of photoresist
12
is correctly transferred into etched layer
11
. As
FIG. 1C
shows, although thickness of photoresist
12
is decreased and pattern of photoresist
12
slightly changed, pattern of photoresist
12
is essentially correctly transferred into etched layer
12
. As
FIG. 1D
shows, both thickness of photoresist
12
is decreased and pattern of photoresist is changed, to let pattern of etched layer
11
is significantly different from pattern of photoresist
12
. Indisputably, the more thickness of photoresist
12
is, the more removing rate of photoresist
12
is, the less distance between neighboring opening
13
is, and then the more cases of
FIG. 1C
or
FIG. 1D
are, to let assurance of etch process is decreased.
Because pattern of photoresist
12
is dependent on configuration of semiconductor and is not adjustable, also because distance between neighboring openings
13
is decreased while critical dimension is decreased, the most direct solution of previous problem is increasing thickness of photoresist
12
. However, whenever thickness of photoresist
12
is increased, difficulty and cost of photolithography also are increased, and then production is decreased. Therefore, increasing thickness is not a general solution for all photoresist
12
, especially while both thickness of photoresist
12
and width of opening
13
let aspect ration of opening
13
is too large to be properly formed.
Another often-seen solution is to harden photoresist
12
by ultra-violet light (UV), especially to harden surface of photoresist
12
to let anti-etching ability of photoresist
12
is increased and removed rate of photoresist
12
is decreased. As FIG.
1
E and
FIG. 1F
show, after photoresist
12
is formed and before process is not started, photoresist
12
is exposed by ultra-violet light
14
to let surface of photoresist
12
is transferred to hardened photoresist
15
. After that, etch process is performed by using both photoresist
12
and hardened photoresist
15
as required mask. Because removed rate of hardened photoresist
15
is smaller than removed rate of photoresist
12
, after etch process is finished, thickness of both residual hardened photoresist
15
and residual photoresist
12
is smaller than thickness of residual photoresist
12
which is not hardened. Thus, disadvantages such as thinner photoresist
12
and changed pattern could be effectively improved.
However, while photoresist
12
is hardened by ultra-violet light, following disadvantages still are unavoidable. First, ultra-violet light
14
only could harden surface of photoresist
12
and then thickness of hardened photoresist
15
is finite, thus, photoresist
12
still must be thick enough to ensure pattern could be accurately transferred after hardened photoresist
12
is totally consumed. Second, glow discharge of etching process is in the range of near ultra-violet light, which would reduce thermal stability of both photoresist
12
and hardened photoresist
15
and induce unavoidable deformation. Third, absorb efficiency of ultraviolet light depends on material of photoresist
12
and then different material requires different wavelength of ultra-violet light, thus, not only fabrication is complicated for wavelength of ultra-violet light must be adjusted but also some materials of photoresist could not be properly hardened by ultra-violet light. Fourth, temperature of expose process under ultra-violet light is high, shape of photoresist
12
maybe changed. Fifth, power of ultra-violet light is low for most available ultra-violet sources of practical fabrication line, then required period for exposing under ultra-violet light is long and efficiency of fabrication line is decreased.
In short, each of current technologies for solving consumption of photoresist during etch process is not perfect, and then it is desired to develop new technology for enhancing anti-etching ability of photoresist.
SUMMARY OF THE INVENTION
One main object of this invention is to present method of forming photoresist anti-etching ability.
Another main object of this invention is to present a method for increasing process window and reducing required thickness of photoresist.
Still one main object of this invention is to present a method of etching with anti-etching photoresist.
This present invnetion provides a method of enhancing photoresist anti-etching ability, especially is a method which is performed before etch process, at least includes follows. Provide a substrate and form a photoresist with a pattern on the substrate, then put both photoresist and substrate in a low pressure environment, and then treat photoresist by an electron beam to let at least part of photoresist is hardened. After photoresist is treated by electron beam, photoresist is hardened and has anti-etch ability, thus, precision of etch process is enhanced and corresponding pattern is more precise.
Other preferred embodiments are methods of etching with anti-etching photoresist. One embodiment at least includes follows. Provide a substrate, wherein a patterned photoresist is located on, and simultaneously perform an electron beam expose process and an etch process, wherein electron beam exposes process exposes patterned photoresist by electron beam and etch process uses patterned photoresist as a mask. Another embodiment at least includes follows. Provide a substrate, wherein a patterned photoresist is located on, and alternately perform numerous electron beam expose process and numerous etch process, wherein electron beam exposes process exposes patterned photoresist by electron beam and etch process uses patterned photoresist as a mask. Obviously, in both previous embodiments. Hardened photoresist is continuously consumed but also is continuously formed.


REFERENCES:
patent: 5660957 (1997-08-01), Chou
patent: 6358670 (2002-03-01), Wong

Affiliated with

Also associated with

Rating

Method of enhancing photoresist anti-etching ability 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 of enhancing photoresist anti-etching ability, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of enhancing photoresist anti-etching ability will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3145702