Method and apparatus for measuring feature dimensions using controlled dark-field illumination
US4965842A · kind A · utility
12Cited by
22References
16Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 14, 1987 |
| Grant date | Oct 23, 1990 |
| Priority date | — |
| Expiry date | Dec 14, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T5/20
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for measuring feature dimensions uses selective dark-field illumination to illuminate a target from a single direction at a low angle to the plane of the target. Opposing edges of the target elements are distinguished and captured in separate images. The images are filtered using a Gaussian convolution operator and a Laplacian operator. The signs of the filtered images are correlated at various offsets. The relative displacement of the images which produces the maxium correlation value is used to calculate the average dimension of the target elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.