Method and apparatus for controlling plasma etching
US4208240A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 26, 1979 |
| Grant date | Jun 17, 1980 |
| Priority date | — |
| Expiry date | Jan 26, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/272
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus are disclosed for controlling plasma etching processes in which a thin layer is etched away to expose a substrate. Coherent light is directed onto the surface being etched, so that the change in reflectivity of the surface upon exposure of the underlying substrate produces a detectable change in the characteristics of the light reflected. A derivative detector having a variable timer is provided to sample continuously the reflected light and provide a control signal in response to a predetermined change in the characteristics of the light reflected, which is used to terminate the plasma etch process before an overetch condition occurs. The method and apparatus of the invention will detect a desired end point of etching through insulation to an underlying metal substrate, through metal to an underlying insulation substrate, through one insulation type to an underlying substrate of another insulation type and through one metal to an underlying substrate of another metal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.