Correcting the polygon feature pattern with an optical...

Details Correcting the polygon feature pattern with an optical... Correcting the polygon feature pattern with an optical...

2002-01-02

2004-07-27

Young, Christopher G. (Department: 1756)

Radiation imagery chemistry: process, composition, or product th

Including control feature responsive to a test or measurement

C430S296000, C430S942000

Reexamination Certificate

active

06767679

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an optical proximity correction, and more particularly to an optical proximity correction method for modifying the polygon feature pattern with inner corner.
2. Description of the Prior Art
The minimum feature sizes of integrated circuits (ICs) have been shrunk for years. This feature size reduction, various process limitations have made IC fabrication more difficult. One area of fabrication technology in which such limitations have appeared is photolithography.
An important component of photolithographic apparatus is a “reticle” which includes a pattern corresponding to features at one layer in an IC design. Such reticle typically includes a transparent glass plate covered with a patterned light blocking material such as chromium.
For advance SOC (system on chip), the complexity of design and the file size of mask tooling both dramatically increased. For example, a 50 GB (giga bytes) file size, it may take two days for mask writing. Therefore, how to reduce the file size is an important issue. The traditional OPC (optical proximity correction) methodology corrects the inner corner pattern by adding extra serifs. For a single inner corner, the number of data points can be expanded from one to five. Overall, this approach would increase the output file size and dramatically increase the mask writing time since the serif require adding extra data points. Thus, the data points of the file are increased and the writing speed is slow down.
FIGS. 1A
to
3
C show the conventional OPC (optical proximity correction) using inner serif for L-, T-, and cross-shaped feature patterns. Extra data points and mask writing units are required to define these OPC patterns. Small mask writing units causes a large file size, a complex and slower mask writing procedure.
FIG. 1A
to
FIG. 1C
shown a reticle corresponding to an integrated circuit (IC) pattern.
FIG. 1A
shows an un-corrected L-shaped feature pattern
10
. To avoid the L-shaped feature pattern with a corner, there is a method to modify the un-corrected L-shaped pattern
10
with an OPC method such as serif method to form a corrected L-shaped feature pattern
10
a
which has an inner corner
14
as shown in FIG.
1
B. Therefore, the extra data points and the file size are also increased after correction steps. The un-corrected L-shaped feature pattern
10
has only one data point
12
A, however, the corrected L-shaped feature pattern
10
a
has four extra data points,
12
B,
12
C,
12
D, and
12
E. Therefore, the computer data-processing capacity and file size are increased that according to increase of data points. Referring to
FIG. 1C
, the corrected feature pattern
10
a
is divided into five rectangular feature patterns
16
a
through
16
e
, such that increase two extra mask units after the mask dividing step.
Then, referring to
FIG. 2A
shown the uncorrected T-shaped feature pattern
20
with two data points
22
A and
22
B. The correcting steps as the
FIG. 1A
to
FIG. 1C
, a corrected T-shaped feature pattern
20
a
with two inner corners
24
A and
24
B are formed after serif correction method as shown in FIG.
2
B and has eight extra data points
22
C through
22
J. In the
FIG. 2C
, there are seven extra mask units
26
a
through
26
h
after a mask-dividing step. Next, referring to
FIG. 3A
that shown the un-corrected crossed-shaped feature pattern
30
with four data points
32
A through
32
D. As the above-mentioned, after serif correction method, the corrected crossed-shaped feature pattern
30
a
with four inner corners
34
a
through
34
d
and has sixteen extra data points
32
E through
32
T, which are increased after OPC method. Therefore, the output file size is increased and the mask writing time is dramatically increased since the serif requires adding extra data points.
Next, the
FIG. 4
is schematic vertical views showing a contour image of the un-corrected crossed-shaped feature pattern
30
. The scope of the solid line is an original un-corrected crossed-shaped feature pattern
30
, after exposure steps, the scope of dotted line is a simulation area image
40
is smaller than the original un-corrected crossed-shaped feature pattern
30
. But the simulation area images have four corners
42
a
,
42
b
,
42
c
, and
42
d
, and further the corner still causes the pattern inspection issue. Furthermore, in order to solve the corner issue, the conventional technique is utilized a serif method to modify the conventional crossed-shape feature pattern
30
. According to
FIG. 3B
, after exposure step, the simulation area image
40
a
is approach to the original feature pattern
30
a
with using serif method as shown in FIG.
5
. In the
FIG. 5
, even though the simulation area image
40
a
is approach to the original feature pattern
30
a
, but the simulation area image
40
a
has corners and still causes the file size increased, loading mask time, and mask writing time are increased.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method is provided to correct the feature pattern with inner corner fidelity by an optical proximity correction (OPC) method, the improved method substantially reduces the OPC output file size, improves the mask writing with a few rectangular-shaped writing units or trapeze-shaped writing units for regular mask writing, and save the mask inspection time.
It is an object of this present invention to provide an improved OPC (optical proximity correction) method without adding extra serifs to obtain a high-resolution pattern mask.
It is another object of this present invention to provide an effectively OPC to reduce the OPC output file size.
It is still another object of this present invention to provide an OPC method to correct the polygon feature pattern and perform the plurality of the mask writing with a few rectangular-shaped writing units or trapeze-shaped writing units for regular mask writing to improve the mask writing time.
It is a further object of this present invention to provide a method to improve the mask uniformity and feature pattern inspection.
In one embodiment, the approach of the present invention uses a pattern section without adding extra serif to correct the polygon feature pattern. Correcting the polygon feature pattern with at least one inner corner that can achieve effectively OPC (optical proximity correction) without adding extra data points and mask writing units. Therefore, the present invention can instead of four as the conventional serif and achieve the effectively OPC. In addition, the mask writing time is also improved since the original feature pattern is divided into a few rectangular-shaped mask writing units or trapeze-shaped mask writing units for regular mask writing units, and the inner corner is/are not in the middle of each of the divided mask writing unit (rectangular mask writing units or trapeze mask writing units). The feature pattern inspection is also simplified and easier to calibration since a simple geometry other than complex serif is used.


REFERENCES:
patent: 6080527 (2000-06-01), Huang et al.

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