Wafer stage assembly, servo control system, and method for operating the same
US6686991B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 6, 2000 |
| Grant date | Feb 3, 2004 |
| Priority date | — |
| Expiry date | Nov 6, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70716
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A wafer stage assembly, wafer table servo control system, and method for operating the same, are provided for use in combination with a projection lens assembly in a semiconductor wafer manufacturing process. The wafer stage assembly includes a wafer stage base supporting a wafer stage to position the semiconductor wafer, a wafer table connected to the wafer stage to support the wafer, a plurality of sensors, and an actuator. The sensors include a first sensor to determine a position of an exposure point on the wafer relative to the projection lens assembly, and a second sensor to determine a position of a focal point of the projection lens assembly relative to the exposure point. To increase focusing properties of the projection lens assembly, in response to the determined positions of the exposure point and the focal point, the actuator moves the wafer table so that the exposure point substantially coincides with the focal point. The wafer table servo control system is provided to operate the wafer stage assembly. The servo control system includes a first sensor controller to generate a first position signal of an exposure point on the wafer table relative to a projection lens as…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.