Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Reexamination Certificate
2000-12-21
2003-02-25
Rosasco, S. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
C430S296000, C430S322000
Reexamination Certificate
active
06524753
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a semiconductor memory device; and, more particularly, to a method for manufacturing a phase shift mask by employing a chemical layer for a chemical swelling process (CSP) instead of a photoresist layer.
DESCRIPTION OF THE PRIOR ART
Generally, a phase shift mask is used to shift a phase of a light on the mask using an interference effect which reduces a space frequency of a pattern or increases a contrast on a corner. The phase shift mask provides a high resolving power and an increase of a depth of focus (DOF) so that it is possible to fabricate a pattern for use in a device with a high integration.
Referring to
FIGS. 1A
to
1
I, there are provided cross section views setting forth a conventional method for manufacturing the phase shift mask.
The manufacturing steps begin with a preparation of the substrate
110
made of a synthetic quartz. Thereafter, a shift layer
112
, a chromium (Cr) layer
114
and a first photoresist layer
116
is formed on top of the substrate
110
subsequently, as shown in FIG.
1
A. The chromium layer
114
is formed to a thickness of approximately 1,000 Å including CrOx and the shift layer
112
is formed to the thickness of approximately 950 Å including MoSiN.
In a next step as shown in
FIG. 1B
, the first photoresist layer
116
is patterned into a first predetermined configuration by using an E-beam or laser beam, thereby obtaining a first photoresist pattern
116
A.
In an ensuing step, the chromium layer
114
is patterned into the first predetermined configuration by using a dry etching such as an inductively coupled plasma (ICP) or a reactive ion etching (RIE), or wet etching process such as a spin spray method, so that a patterned chromium layer
114
A is obtained, as shown in FIG.
1
C. The first photoresist pattern
116
A plays a role as an etching mask in post manufacturing steps.
Thereafter, the shift layer
112
is patterned into the first predetermined configuration by using an inductively coupled plasma (ICP), thereby forming a patterned shift layer
112
A, as shown in FIG.
1
D.
In a subsequent step, as shown in
FIG. 1E
, the first photoresist pattern
116
A is stripped off by using H
2
SO
4
/H
2
O
2
+SC-1.
In a next step, a second photoresist layer
118
is formed on the patterned chromium layer
114
A and the substrate
110
, as shown in FIG.
1
F.
In an ensuing step, the second photoresist layer
118
is patterned into a second predetermined configuration by using the laser beam, thereby obtaining a second photoresist pattern remaining on the patterned chromium layer
114
A which is disposed on each end of the substrate
110
as shown in FIG.
1
G.
Thereafter, two patterned chromium layer
114
A in the middle of the substrate
110
is removed by using the second photoresist pattern as the etching mask as shown in FIG.
1
H.
Finally, the second photoresist pattern
116
A remaining on the patterned chromium layer
114
A on each end of the substrate is stripped off by using H
2
SO
4
/H
2
O
2
+SC-1 as shown in FIG.
1
I.
As described above, the conventional method for manufacturing the phase shift mask may involve long and tedious steps. That is, formation and removal of the photoresist may be repeated twice thereby increasing the total manufacturing steps.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for manufacturing a phase shift mask by employing a chemical swelling process (CSP) chemical layer instead of a photoresist layer, whereby manufacturing steps are shortened.
In accordance with one aspect of the present invention, there is provided a method for manufacturing a phase shift mask, the method comprising the steps of: a) forming a shift layer, a metal layer and a photoresist layer on a substrate subsequently; b) patterning the photoresist layer into a predetermined configuration, thereby obtaining a first, a second, a third and a fourth photoresist pattern; c) forming a chemical swelling process (CSP) chemical layer on the photoresist patterns and an exposed portion of the substrate; d) patterning the CSP chemical layer using masks over the first and the fourth photoresist patterns, whereby the CSP chemical layer on the first and the fourth photoresist patterns remains thereon; e) patterning an exposed portion of the metal layer into the predetermined configuration using the second and the third photoresist patterns as masks; f) patterning the exposed portions of the shift layer into the predetermined configuration; and g) removing the first and fourth photoresist patterns.
REFERENCES:
patent: 5543253 (1996-08-01), Park et al.
Choi Sang-Tae
Jang Hwan-Soo
Hyundai Electronics Industries Co,. Ltd.
Rosasco S.
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