Wafer alignment station
US4457664A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 1982 |
| Grant date | Jul 3, 1984 |
| Priority date | — |
| Expiry date | Mar 22, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S414/137
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
An automatic wafer alignment station is disclosed for aligning a wafer having flats about its centroid with the flats oriented in a preselected spatial direction. The wafer is held by a vacuum chuck which is operatively connected to a motor driven carriage for controlled movement about an X axis, to a .theta. actuator carried by the carriage for controlled rotation about the axis of the chuck, and to a Z actuator carried by the carriage for controlled motion about a Z axis. An X capacitive sensor and a Z capacitive sensor are positioned near the wafer. An X processing and Z compensating circuit is responsive to the X and the Z capacitive sensor output signals and provides an electrical signal that has values which exclusively represent the position of the edge of the wafer along the X axis only over a predetermined angular range. Circuit means including an A/D converter and a microprocessor respond to the electrical signal and produce a plurality of corrective signals to the X, Y, and .theta. actuators for aligning the wafer about its centroid and for orienting the flats of the wafer in a preselected spatial orientation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.