Feed-forward lithographic overlay offset method and system
US6694498B2 · kind B2 · utility
8Cited by
14References
20Claims
0Family size
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Key dates
| Filing date | Dec 13, 2001 |
| Grant date | Feb 17, 2004 |
| Priority date | — |
| Expiry date | Mar 20, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70633
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and system embodying the present invention for predicting systematic overlay affects in semiconductor lithography. This method is a feed-forward method, based on correlation of current and prior aligned levels, to predict optimum overlay offsets for a given lot. Instead of using population averaging, which ignores process variability, it acknowledges the variability and uses prior measurements to advantage. The principle, backed by production data, is that “systematic” overlay errors are just that: Image placement errors which persist through processing and will be predictable through time and processing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.