Method of forming mask with angled struts of reduced height

Details Method of forming mask with angled struts of reduced height Method of forming mask with angled struts of reduced height

1997-12-19

2001-04-24

Huff, Mark F. (Department: 1756)

Radiation imagery chemistry: process, composition, or product th

Radiation modifying product or process of making

Radiation mask

C430S313000

Reexamination Certificate

active

06221537

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to semiconductor devices, and more particularly to a method of forming a semiconductor device used as a lithographic mask for patterning semiconductor devices.
BACKGROUND OF THE INVENTION
Lithography processes are used to transfer patterns from a mask to a semiconductor device. As feature sizes on semiconductor devices decrease into the submicron range, there is a need for new lithography processes to pattern high-density semiconductor devices. Projection electron-beam lithography is a well-known reduction technique for patterning semiconductor devices. In general, a projection electron-beam lithography system scans a beam across a mask to create an image on the semiconductor device. Electron optics can be inserted to provide a means of image reduction. One particular type of projection e-beam lithography is known as Scattering with Angular Limitation in Projection Electron-Beam Lithography developed by Lucent Technologies, Incorporated of Murray Hill, N.J. The basic principles of this technique are illustrated in prior art FIG.
1
.
From prior art
FIG. 1
, a mask
10
having a patterned scattering layer
14
is provided on membrane
12
, through which an electron beam is projected, as represented by the flux arrows
13
. The patterned scattering layer produces more electron scattering than the membrane
12
as a result of the difference in atomic numbers between the composition of the patterned scattering layer
14
and the membrane
12
, i.e., the patterned scattering layer
14
has a higher atomic number than that of the membrane
12
. The scattering effect
16
of the electron beam through portions of the mask
10
is illustrated in FIG.
1
. As shown, those portions of the electron beam that pass through the patterned scattering layer
14
tend to be scattered through larger angles, as depicted by the scattering effect
16
, when compared with those less scattered portions
17
that pass between unpatterned portions of the scattering layer
14
.
As shown, the electron beam that passes through the mask
10
is focused through an electron focusing system represented by lens
20
. The electron beam then passes through back focal plane filter
30
having an aperture
18
that is provided to permit passage of those portions of the electron beam that were not scattered by the patterned scattering layer
14
of the mask
10
through some finite angle. The electron beam is then projected onto a semiconductor wafer
40
having a plurality of die
42
and a resist layer
44
spun on the semiconductor wafer
40
by conventional techniques. The electron beam forms a high contrast image including areas of low intensity formed by those scattered portions
16
of the electron beam that pass through patterned portions of the mask
10
, and areas of relatively high intensity formed by those unscattered portions
17
of the electron beam that pass through the unpatterned areas of the mask
10
. In this way, a high-resolution image may be projected onto the resist layer
44
, which is then developed to form an exposed resist layer. The patterned resist layer
44
may be used as an etch mask for the underlying material. It is noted that the electron optics of the system may be adjusted so as to provide a reduction in image size, typically 4× or one-fourth the image size on the mask
10
.
Prior art
FIG. 2
is a cross-sectional view of the membrane film
12
and patterned scattering layer
14
(grouped in dashed line
25
), shown in
FIG. 1
, oriented onto a mask
26
. In prior art
FIG. 2
, a silicon substrate
27
with a membrane film
12
on top of the silicon substrate
27
has been patterned to form two different struts, struts
29
(shown by dashed lines) and struts
31
. The two types of struts are formed depending on the choice of orientation of the single crystal silicon substrate and are not present at the same time but are shown together here for exemplary purposes. The problem with the strut
29
is that the angle
32
at which the strut
29
contacts the membrane film
12
is at about 54 degrees which results in increased coverage of the membrane film
12
. This, in turn, leaves less unobstructed membrane film
12
on which the patterned scattering layer
14
must be located between the struts. Further, the problem with the strut
31
is that due to the horizontally long and narrow shape of the strut
31
, such a strut has a high aspect ratio which results in an unstable support structure for the membrane film
12
.
A need therefore exists for forming a strut that takes up less surface area of the membrane film
14
while also providing a stable support mechanism for that membrane film.


REFERENCES:
patent: 5079112 (1992-01-01), Berger et al.
patent: 5318687 (1994-06-01), Estes et al.
patent: 5580687 (1996-12-01), Leedy
patent: 5770336 (1998-06-01), Choi
patent: 5781607 (1998-07-01), Acosta et al.
patent: 5846676 (1998-12-01), Chiba et al.
patent: 5866281 (1999-02-01), Guckel et al.
patent: 5899728 (1999-05-01), Mangat et al.

Affiliated with

Also associated with

Rating

Method of forming mask with angled struts of reduced height 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 forming mask with angled struts of reduced height, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of forming mask with angled struts of reduced height will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2453001