Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
1996-09-19
2001-12-18
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S191000, C430S192000, C430S270100, C430S328000, C430S926000
Reexamination Certificate
active
06331383
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention and Related Art
The present invention relates to a photosensitive composition, particularly a photosensitive composition used as a resist composition, a method for patterning using the same, and a method for manufacturing a semiconductor device.
A method for forming fine patterns in conventional manufacturing processes of semiconductor devices is described in “Silicon-Added Bilayer Resist (SABRE) System, W. C. McColgine, et, al. SPIE. Vol. 920, pp.260-267 (1988)”, for example. The method will be explained with reference to
FIGS. 1A
to
1
D.
As shown
FIG. 1A
, a resist, e.g. a polyimide resist, is applied onto a semiconductor substrate
4
to form an underlying resist film
3
, and then an i-line sensitive resist is applied thereon to form an overlay resist film
2
(hereinafter the combination of the semiconductor substrate
4
and resist films
2
and
3
is called “integral article”). Ultraviolet light, for example, having the i-line wavelength (365 nm) is irradiated to the overlay resist film
2
through a given mask (not shown in the figure) to expose the overlay resist film
2
to the i-line
1
. A developed pattern
5
as shown in
FIG. 1B
is formed by developing the overlay resist film
2
. Next, the integral article is exposed to vapor of a sililation agent
6
, e.g. hexamethyldisilazane while heating as shown in FIG.
1
C. Only the developed pattern
5
is sililated thereby to form a sililated layer
7
on the underlying resist film
3
. Then, as shown in
FIG. 1D
, the underlying resist film
3
is etched by oxygen reactive ion etching (RIE) with an etching mask of sililated layer
7
to form a fine pattern. In
FIG. 1D
, the resulting SiO
2
layer
9
is formed by oxygen plasma
8
.
The method for forming a fine pattern set forth above has the following problems:
Dry etching of the underlying resist film
3
is unavoidable to transfer the developed pattern formed in the overlay resist film
2
to the underlying resist film
3
. Therefore, an exclusive etcher for organic film must be employed, and the process requires complicated optimization to improve planar uniformity and selective or etching ratio.
In particular, when a general etcher for organic film is used for etching in the transfer of the fine developed pattern in the overlay resist film
2
to the thick underlying resist film
3
(for example, 1.5 &mgr;m thick), a vertical pattern is barely formed. In detail, because the general etcher for organic film has a strong reactivity, the underlying resist film is isotropically etched and undercut. Therefore, an etcher exhibiting a high anisotropic etching characteristic is required for transferring the fine developed pattern in the overlay resist film
2
to the underlying resist film
3
.
Further, significantly complicated process optimization is required for the selection of etching gas, the mixing ratio of a plurality of gasses, gas pressure, temperature, Rf bias, extraction voltage bias, and Rf frequency.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a photosensitive composition not requiring an exclusive etcher and complicated process optimization.
It is another object of the present invention to provide a method for patterning not requiring an exclusive etcher and complicated process optimization.
It is a further object of the present invention to provide a method for manufacturing a semiconductor device not requiring an exclusive etcher and complicated process optimization.
These and other objects are attained by a photosensitive composition characterized in that the transmittance of the light out of the range of the exposing wavelength decreases by the exposure.
In the photosensitive composition, it is preferable that the transmittance of the i-line decreases by exposing the composition to far ultraviolet light. More preferably, the composition contains a photoacid generator for forming an acid by exposing it to far ultraviolet light and a pH indicator which colors the composition so as to exhibit an absorption band comprising the i-line wavelength region in the presence of the acid.
In the second aspect of this invention, a photosensitive composition comprises a photoacid generator for forming an acid by exposing the composition to far ultraviolet light, a pH indicator capable of changing color so as to exhibit an absorption band comprising the i-line wavelength region in the presence of the acid, and an i-line photosensitizer chemically changing by exposing to the i-line.
Preferably, the solubility of the i-line photosensitizer in an alkaline solution varies by exposing to the i-line.
In the third aspect of this invention, a method for patterning comprises: exposing a predetermined portion of a photosensitive composition to far ultraviolet light so as to decrease the transmittance of the i-line at the exposed portion; exposing the photosensitive composition to the i-line; and developing the photosensitive composition.
In the fourth aspect of this invention, a method for manufacturing a semiconductor device comprises: a step for forming a photosensitive film by applying a photosensitive composition, in which the transmittance of the light out of the range of the exposing wavelength decreases by the exposure, to at least a portion of a substrate; a step for exposing a predetermined portion of the photosensitive film to light of a first wavelength region to decrease the transmittance of light of a second wavelength region at the surface layer of the predetermined portion of the photosensitive film; a step for exposing the resist film to the light of the second wavelength region by using the surface layer of the predetermined portion as a mask; and a step for developing the photosensitive film.
Preferably, the light of the first wavelength region is far ultraviolet light and the light of the second wavelength region is i-line.
In the fifth aspect of this invention, a method for patterning comprises: applying a photosensitive composition, in which the transmittance of the i-line decreases by exposing to far ultraviolet light, to a substrate; exposing a predetermined portion of the photosensitive composition to far ultraviolet light to form a portion, in which the transmittance of the i-line decreases, exposing the photosensitive composition to the i-line by acting the predetermined portion as a mask; and developing the photosensitive composition to form a predetermined pattern.
REFERENCES:
patent: 4659649 (1987-04-01), Dickinson et al.
patent: 5064741 (1991-11-01), Koike et al.
patent: 5229254 (1993-07-01), Lohaus et al.
patent: 5256522 (1993-10-01), Spak et al.
patent: 5332648 (1994-07-01), Kihara et al.
patent: 5364734 (1994-11-01), Pawlowski et al.
W.C. McColgin, et al., “Silicon-added bilayer resist (SABRE) system”, SPIE vol. 920 Advances in Resist Technology and Processing V(1988) pp. 260-267.
Canon Kabushiki Kaisha
Chu John S.
Fitzpatrick ,Cella, Harper & Scinto
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