US6150231A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Overlay measurement technique using moire patterns
Assignee: Infineon Technologies AG
•
Filing: 1998-06-15
•
Granted: 2000-11-21
•
Expires: 2018-06-15
Abstract
Abstract Misalignment between two masking steps used in the manufacture of semiconductive devices in a wafer is determined by having a special alignment pattern on each of two masks used in the process and forming images of the masks on the semiconductor devices with the images of the alignment patterns being superimposed over one another to form a Moire pattern. The Moire pattern is compared with other Moire patterns known to correspond to particular amounts of misalignment of the masks to see if it corresponds to an acceptable alignment.
Inventors
- 👤 Karl Paul Muller
- 👤 Venkatachalam C. Jaiprakash
- 👤 Christopher J. Gould
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 13:24
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70605; G03F7/70616; G03F7/70633; H; H10; H10P; H10P74/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
131 words
A process for detecting misalignment of the two masking steps in the manufacture of semiconductive devices comprising the steps of: including in each of the two masks used for the masking steps a repetitive pattern of marks that is made different by a prescribed amount in the two masks such that when superposed on one another the masks generate a Moire pattern that is a measure of the degree of misalignment between the two masks; using the two masks to form at the surface of the semiconductive wafer being processed, the patterns of marks of the two masks superposed on one another for generating a Moire pattern; observing optically the Moire pattern generated; and comparing the Moire pattern observed with Moire patterns corresponding to an acceptable alignment between the two masks.
Claim 2
Dependent Claim
131 words
A process for detecting misalignment of the two masking steps in the manufacture of semiconductive devices comprising the steps of: including in each of the two masks used for the masking steps a repetitive pattern of marks that is made different by a prescribed amount in the two masks such that when superposed on one another the masks generate a Moire pattern that is a measure of the degree of misalignment between the two masks; using the two masks to form at the surface of the semiconductive wafer being processed, the patterns of marks of the two masks superposed on one another for generating a Moire pattern; observing optically the Moire pattern generated; and comparing the Moire pattern observed with Moire patterns corresponding to an acceptable alignment between the two masks.
Claim 3
Dependent Claim
36 words
The process of claim 1 in which the repetitive patterns in the two masks comprise a plurality of lines and spaces that differ only in the widths of the lines and spaces in the two patterns.
Claim 4
Dependent Claim
35 words
The process of claim 2 in which the lines and spaces in each pattern are uniform in width and there is a uniform difference in widths of the lines and spaces of the two patterns.
Claim 5
Dependent Claim
39 words
The process of claim 1 in which the pattern of marks in each of the two masks is a checkerboard pattern of uniform squares and the size of the squares in the two patterns differs by a prescribed amount.
Claim 6
Dependent Claim
27 words
The process of claim 2 in which the degree of difference in the widths of the lines and spaces in the two patterns is about one percent.
References Cited (Backward Citations)
US3690881A
Cited
US4568189A
Cited
JPH0260120A
Cited
EP0370834A2
Cited
JPH03154803A
Cited
EP0534720A1
Cited
US5388517A
Cited
GB2293026A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-11-21 | 2004-05-22 | 2004-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-11-21 | 2008-05-22 | 2008-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-11-21 | 2012-05-22 | 2012-11-21 | $7700.00 | Window Closed / Lapsed |