Method of particle analysis on a mirror wafer
US5267017A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 20, 1992 |
| Grant date | Nov 30, 1993 |
| Priority date | — |
| Expiry date | May 20, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/307
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for reducing targeting errors encountered when trying to locate contaminant particles in a high-magnification imaging device, based on estimates of the particle positions obtained from a scanning device. The method of the invention uses three techniques separately and in combination. The first technique includes selecting at least three reference particles, to provide multiple unique pairs of reference particles for computation of an averaged set of coordinate transformation parameters, used to transform particle position coordinates from the coordinate system of the scanning device to the coordinate system of the imaging device. The averaged transformation parameters result in much smaller targeting errors between the estimated and actual positions of the particles. The targeting errors are further reduced by the use of multiple scans of the scanning device. In a third technique, accumulated reference particle targeting errors observed in prior processing of other wafers are used to reduce these targeting errors when processing a new wafer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.