Method of fabricating phase shift mask

Details Method of fabricating phase shift mask Method of fabricating phase shift mask

1999-04-21

2001-12-25

Huff, Mark F. (Department: 1756)

Radiation imagery chemistry: process, composition, or product th

Radiation modifying product or process of making

Radiation mask

C430S322000, C430S323000, C430S324000

Reexamination Certificate

active

06333129

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of fabricating semiconductor devices, and more particularly, to a method of fabricating a phase shift mask.
2. Description of the Related Art
A general blank mask is formed by forming a chrome layer as a transmission preventing film on a quartz substrate and coating a photosensitive film on the resultant structure. A phase shift mask (PSM) is effective in improving resolution and the depth of focus in a process for forming a contact hole.
A halftone PSM generates a sidelobe effect. Accordingly, a photosensitive film in an undesired region is damaged. Thus, if such a problem is not solved, the application field of the halftone PSM becomes narrow.
The sidelobe effect becomes more severe as a pitch between devices becomes narrower due to increasing integration of semiconductor devices. To solve this problem, a halftone rim PSM also uses a rim-type structure used by a quartz PSM.
A conventional rim-type PSM and a fabrication method thereof will now be described in brief referring to the attached drawings.
Referring to
FIG. 1
, in the conventional rim-type PSM, a plurality of grooves
12
, which will become phase shift regions, are formed at regular intervals in a quartz substrate
10
. Light shield film patterns
14
are formed on the quartz substrate
10
between the grooves
12
, and a rim region
14
a
is formed between the light shield pattern
14
and the groove
12
.
Referring to
FIG. 2
, in a conventional rim-type halftone PSM, phase shift layer patterns
16
are formed on a quartz substrate
10
, between phase non-shift regions
17
. Light shield film patterns
18
are formed on the phase shift layer patterns
16
. A rim region
18
a
is formed between the light shield film pattern
18
and the phase shift layer pattern
16
.
A method of fabricating the conventional rim PSM shown in
FIG. 1
will now be described.
Referring to
FIG. 3
, a light shield film (not shown) is formed on the quartz substrate
10
. A photosensitive film pattern
22
for exposing a predetermined region of the light shield film is formed on the light shield film. An exposed portion of the light shield film is removed using the photosensitive pattern as a mask, thereby forming a light shield film pattern
20
for exposing a predetermined region of the substrate in which phase shifting occurs. Then, the photosensitive film pattern
22
is removed. Consequently, as shown in
FIG. 4
, a groove
24
is formed to a depth which can provoke phase shifting, in the exposed region of the quartz substrate
10
.
A photosensitive film pattern
26
which exposes a portion of the light shield film pattern
20
adjacent to the groove
24
is formed on the light shield film pattern
20
, in FIG.
5
. The exposed portion of the light shield film pattern
20
is removed using the photosensitive film pattern
26
as an etch mask. The photosensitive film pattern
26
is removed. Consequently, a phase non-shift region
24
a
is set on the quartz substrate
10
at the circumference of the groove
24
, in FIG.
6
.
A method of fabricating the conventional rim-type halftone PSM shown in
FIG. 2
will now be described.
As shown in
FIG. 7
, in the rim halftone PSM, as opposed to the general rim PSM, a phase shift layer
28
is additionally formed between a quartz substrate
10
and a light shield film
20
. The light shield film
20
and the phase shift layer
28
are anisotropically etched using a photosensitive film pattern
30
, which is formed on the light shield film
20
and exposes part of the light shield film
20
, as an etch mask. Then, the photosensitive film pattern
30
is removed. As a result, as shown in
FIG. 8
, a predetermined region
32
of the quartz substrate
10
is exposed. This region is a phase non-shift region.
Referring to
FIG. 9
, a photosensitive film pattern
34
which exposes a portion of the light shield film
20
adjacent to the exposed region
32
on the quartz substrate
10
is formed on the light shield film
20
. The exposed portion of the light shield film
20
is removed using the photosensitive film pattern
34
as an etch mask, thereby exposing the phase shift layer
28
below the exposed portion of the light shield film
20
. An exposed region
36
of the phase shift layer
28
is a phase shift region. The photosensitive film pattern
34
is removed, thereby forming the halftone PSM comprised of the predetermined exposed region
32
on the quartz substrate
20
and the predetermined exposed region
36
on the phase shift layer
28
at the circumference of the exposed region
32
, as shown in FIG.
10
.
In the method of fabricating the conventional rim PSM or rim halftone PSM as described above, the position of a rim region is shifted, in association with a method of forming a light shield film pattern and a main pattern comprised of a phase shift region and a phase non-shift region and setting (forming) a rim region (or a rim pattern). Such a problem occurs because registration, orthogonality, and grid of exposure equipment are not completely consistent with each other. Also, accuracy of the size and position of the rim pattern to be formed between the main patterns of the PSM becomes more important with an increase in the integration of a semiconductor device.
SUMMARY OF THE INVENTION
The present invention is therefore directed to a method of fabricating phase shift masks which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.
An object of the present invention is to provide a method of fabricating a phase shift mask, by which deformation of a main pattern due to the shift of a rim can be prevented by setting (forming) a rim region (or pattern) at an accurate position upon manufacturing a rim phase shift mask.
The above and other objects, may be achieved by a method of fabricating a phase shift mask according to an embodiment of the present invention. In this method, a light shield film is formed on a substrate. First and second regions of the substrate are exposed by patterning the light shield film. A groove is formed in the first region of the substrate. A light shield film pattern formed on the substrate between the groove and the second region is removed.
Here, the formation of the groove may include: coating a first photosensitive film on the entire surface of the resultant structure on which the first and second regions of the substrate are exposed; forming a first photosensitive film pattern exposing the entire first region and a part of the light shield film pattern in contact with the first region, by patterning the first photosensitive film; forming a groove in the first region of the substrate by using the first photosensitive film pattern as an etch mask; and removing the first photosensitive film pattern.
The removal of the light shield film pattern may include: coating a second photosensitive film on the entire surface of the resultant structure on which the first photosensitive film pattern has been removed; forming a second photosensitive film pattern exposing the entire first region of the substrate, the entire light shield film pattern formed on the substrate between the first and second regions, and a part of the second region of the substrate, by patterning the second photosensitive film; etching out the light shield film pattern formed on the substrate between the first and second regions, using the second photosensitive film pattern as an etch mask; and removing the second photosensitive film pattern.
To achieve the above and other objects, there is also provided a method of fabricating a phase shift mask according to another embodiment of the present invention. In this method, a phase shift layer and a light shield film are sequentially formed on a substrate. First and second regions of the phase shift layer are exposed by patterning the light shield film. The substrate is exposed by removing the phase shift layer exposed to the first region. The light shield film formed on the phase shift layer betw

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