Apparatus for measuring difference in shallow level
US4744660A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 1986 |
| Grant date | May 17, 1988 |
| Priority date | — |
| Expiry date | Apr 11, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/22
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for measuring a difference in level in a sample comprises a light source section which provides illumination light of a variable-wavelength. The illumination light is irradiated onto the sample. A group of filters is provided for shielding diffraction light rays of O-order or other than O-order of the light reflected from the sample. The intensity of interference light of the light rays not shielded by the filter group is detected by a light detector which in turn converts it into an electric signal. An arithmetic operation unit receives the electric signal while the wavelength of the illumination light from the light source section is continuously varied. In the arithmetic unit, wavelengths at which the electric signal or detected light intensity takes extreme values are determined, and the level difference in the sample is determined on the basis of those wavelengths.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.