Thin film detection method and apparatus
US5936254A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1997 |
| Grant date | Aug 10, 1999 |
| Priority date | — |
| Expiry date | Mar 11, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0675
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for detecting the presence of a thin film such as a photoresist film on a semiconductor wafer or other substrate. Only when a film is present does the surface reflectance (reflective power) of light incident on the wafer surface vary sinusoidally when the incidence angle of the light is varied. This sinusoidal variation in the reflected optical power is due to interference occurring between the film surface and wafer surface reflections. This method and apparatus allows determining whether an undeveloped photoresist layer is present on a wafer; this is not possible using merely visual inspection especially when an underlying pattern is present. The present method and apparatus may also be used to determine the thickness of a particular thin film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.