Method and apparatus for endpoint detection in a semiconductor wafer etching system
US5151584A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1991 |
| Grant date | Sep 29, 1992 |
| Priority date | — |
| Expiry date | Oct 15, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/26
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A method for endpoint detection in a semiconductor wafer etching system characterized by the steps of: 1) scanning a semiconductor wafer with a narrowly focused laser beam; 2) analyzing a reflected portion of the beam to determine a preferred parking spot on a preferred flat area of the wafer; 3) parking the beam at the preferred spot; and 4) analyzing the reflected portion of the beam to determine when the preferred flat area has been etched through. The beam spot of the laser beam is smaller than the width of the preferred flat area to eliminate noise generated at the transition boundaries of the flat area. Preferably, the wafer is scanned several times along the same beam path to permit the comparison of several scans to determine the preferred parking spot. The apparatus includes a beam forming assembly; a scanning assembly which causes the laser beam to scan across the wafer; a detection assembly responsive to a portion of the laser beam which is reflected off of the wafer; and a controller which operates the laser and the scanning assembly and which is responsive to an output of the detection assembly. When output of the detection assembly indicates a cessation of the charact…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.