Capacitive mask aligner
US4654581A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 12, 1983 |
| Grant date | Mar 31, 1987 |
| Priority date | — |
| Expiry date | Oct 12, 2003 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S148/102
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An aligner for aligning a mask and a wafer during photolithography of a semiconductor chip uses detection of the differential capacitance between two sets of conductive fingers on the mask and ridges on the wafer. An A.C. signal is coupled between the ridges and the fingers and the phase or amplitude of the signals is detected. An aligner utilizing multiple groups of ridges and fingers allows rotational alignment or two axis lateral alignment. An aligner having reference ledges to which the mask and the wafer are capacitively coupled allows alignment when the distance between the mask and the wafer is too great to permit meaningful capacitive coupling between the mask and the wafer to occur.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.