System and method for process variation monitor
US7410737B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 17, 2006 |
| Grant date | Aug 12, 2008 |
| Priority date | — |
| Expiry date | Apr 17, 2026 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/146
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method to extend the process monitoring capabilities of a semiconductor wafer optical inspection system so as to be able to detect low-resolution effects of process variations over the surface of a wafer at much higher sensitivity than heretofore possible. The method consists, in essence, of grouping sensed pixels by geometric blocks over the inspected surface and comparing each block with a corresponding one from another die on the same wager, from another wager of from a stored model image. In one embodiment of the invention, pixel values are compared directly and differences are thresholded at a considerably lower level than during a defects detection process. In another embodiment, there is calculated a signature for each block, based on the sensed light intensity values, and corresponding signatures are compared.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.