Patent US6311319B1 successfully refreshed from Google Patents.
US6311319B1
Expired / Lapsed
US
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Solving line-end shortening and corner rounding problems by using a simple checking rule
Assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
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Filing: 1998-05-22
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Granted: 2001-10-30
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Expires: 2018-05-22
Abstract
Abstract A methodolgy is described which allows a variety of optical proximity corrections to be added to a mask pattern at low cost and with a view to minimizing the number of electron beam exposures that will be needed later when the reticle is prepared. The basic approach is to add serifs and/or hammerheads to the vertices of the mask pattern on the basis of a small number of simple rule checks. The first check is for the presence of an overlapping pattern at the next level. If this is not detected noting is added at the vertex in question. If some overlap is etected, a predefined search area (at the same mask level) is quickly scanned and, if another stripe is found to be located within a preset distance, serifs are added at the appropriate vertices. If no stripe was found, a second search area, further away, is scanned and if a neighbouring stripe is detected this time, larger serifs are added. If the second search also comes up empty, a hammerhead is added at the appropriate line end. The method may be refined by using additional searches, if so desired.
Inventors
- 👤 Chih-Chiang Tu
- 👤 Ren-Guey Hsieh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:10
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70425; G03F7/70433; G03F1/00; G03F1/36; G03F7/70441
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
179 words
A method to correct for the optical proximity effect, comprising: providing upper and lower mask patterns comprising stripes that have edges, represented in a common numerical format that includes vertex co-ordinates; then for the upper mask pattern, executing the steps of: determining, for a vertex, a minimum separation from any stripes of the lower mask; if said minimum separation exceeds a preset value proceeding to another vertex, else computing a first distance, along a first direction, to a first closest edge, and a second distance, along a second direction perpendicular to said first direction, to a second closest edge; at said vertex, adding to the pattern a serif whose width in said first and second directions, and whose length in said second and first directions, varies, to some maximum, in proportion said first and second distances, respectively; if no serif was added to either said vertex or to an adjoining vertex in the same stripe, adding a hammerhead that wraps around both of these vertices; and repeating the foregoing steps until all vertices in the pattern have been considered.
Claim 2
Independent Claim
179 words
A method to correct for the optical proximity effect, comprising: providing upper and lower mask patterns comprising stripes that have edges, represented in a common numerical format that includes vertex co-ordinates; then for the upper mask pattern, executing the steps of: determining, for a vertex, a minimum separation from any stripes of the lower mask; if said minimum separation exceeds a preset value proceeding to another vertex, else computing a first distance, along a first direction, to a first closest edge, and a second distance, along a second direction perpendicular to said first direction, to a second closest edge; at said vertex, adding to the pattern a serif whose width in said first and second directions, and whose length in said second and first directions, varies, to some maximum, in proportion said first and second distances, respectively; if no serif was added to either said vertex or to an adjoining vertex in the same stripe, adding a hammerhead that wraps around both of these vertices; and repeating the foregoing steps until all vertices in the pattern have been considered.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein the stripes have a width that is between about 0.18 and 0.35 microns.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein said minimum separation is about 0.18 microns.
Claim 5
Dependent Claim
19 words
The method of claim 1 wherein the serifs have a width that is between about 0.04 and 0.24 microns.
Claim 6
Dependent Claim
15 words
The method of claim 1 wherein said first direction is perpendicular to a stripe edge.
Claim 7
Dependent Claim
18 words
The method of claim 1 wherein said first and second distances are between about 0.18 and 0.35 microns.
Claim 8
Dependent Claim
193 words
A process for optical proximity correction comprising the sequential steps of: (a) providing a mask pattern that includes stripes having line ends; (b) defining first, second, and third detection areas for each line end; (c) choosing a line end; (d) determining if, relative to a lower layer, an inter-layer pattern exists within the first detection area of the chosen line end; (e) if no inter-layer pattern is detected, proceeding to step (k); (f) determining if an intra-layer pattern exists within the second detection area of the chosen line end; (g) if an intra-layer pattern is detected within the second detection area, adding a first pair of serifs to the chosen line end and proceeding to step (k); (h) determining if an intra-layer pattern exists within the third detection area of the chosen line end; (i) if an intra-layer pattern is detected within the third detection area, adding a second pair of serifs to the chosen line end and proceeding to step (k); (j) adding a hammerhead to the chosen line end; and (k) if unprocessed line ends remain, choosing a line end that has not yet been processed and returning to step (d).
Claim 9
Dependent Claim
193 words
A process for optical proximity correction comprising the sequential steps of: (a) providing a mask pattern that includes stripes having line ends; (b) defining first, second, and third detection areas for each line end; (c) choosing a line end; (d) determining if, relative to a lower layer, an inter-layer pattern exists within the first detection area of the chosen line end; (e) if no inter-layer pattern is detected, proceeding to step (k); (f) determining if an intra-layer pattern exists within the second detection area of the chosen line end; (g) if an intra-layer pattern is detected within the second detection area, adding a first pair of serifs to the chosen line end and proceeding to step (k); (h) determining if an intra-layer pattern exists within the third detection area of the chosen line end; (i) if an intra-layer pattern is detected within the third detection area, adding a second pair of serifs to the chosen line end and proceeding to step (k); (j) adding a hammerhead to the chosen line end; and (k) if unprocessed line ends remain, choosing a line end that has not yet been processed and returning to step (d).
Claim 10
Dependent Claim
14 words
The process recited in claim 7 wherein each line end further comprises multiple segments.
Claim 11
Dependent Claim
20 words
The process of claim 8 wherein said first detection area is a point located a predefined distance from a segment.
Claim 12
Dependent Claim
23 words
The process of claim 7 wherein said first detection area is located between about 0.18 and 0.35 microns from the chosen line end.
Claim 13
Dependent Claim
23 words
The process of claim 7 wherein said second detection area is located between about 0.36 and 0.7 microns from the chosen line end.
Claim 14
Dependent Claim
23 words
The process of claim 7 wherein said second detection area measures between about 0.18 and 0.35 microns by about 0.54 and 1.05 microns.
Claim 15
Dependent Claim
25 words
The process of claim 7 wherein the first pair of serifs each measures between about 0.04 and 0.12 microns by about 0.04 and 0.12 microns.
Claim 16
Dependent Claim
25 words
The process of claim 7 wherein the second pair of serifs each measures between about 0.12 and 0.24 microns by about 0.12 and 0.24 microns.
Claim 17
Dependent Claim
26 words
The process of claim 7 wherein said hammerhead wraps around three sides of a line end with a width that increases with its nearest neighbour distance.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-10-29 | 2005-04-30 | 2005-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-10-29 | 2009-04-30 | 2009-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-10-29 | 2013-04-30 | 2013-10-30 | $7700.00 | Window Closed / Lapsed |