Method for alignment using multiple wavelengths of light
US5952135A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 19, 1997 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Nov 19, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/70
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and apparatus for the alignment of a semiconductor device in preparation for patterning a layer of the device includes using an alignment apparatus which has one or more light sources for producing light at two or more alignment wavelengths. Typically, the semiconductor device will include alignment structures that are to be aligned with corresponding alignment markers on a photomask which contains the desired pattern. The alignment structures on the semiconductor device are often depressions or trenches in a layer of the device. The alignment apparatus determines the position of the alignment structures by observing the contrast in the intensity of light reflected off the region of the device containing the alignment structure and the region of the device adjacent to the alignment structure. This contrast in the intensity of light is wavelength dependent. By providing an alignment apparatus with multiple alignment wavelengths, it is likely that at least one of those wavelengths will provide sufficient contrast to accurately resolve the alignment structures.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.