Wafer testing and self-calibration system

US5642298A · kind A · utility

Assignee

• ADE, Inc. · US

Inventors

• Roy E. Mallory · Bedford, US
• Peter L. Domenicali · Wilmington, US
• Noel S. Poduje · Needham, US
• Alexander Belyaev · Foster City, US
• Peter A. Harvey · Wilmington, US
• Richard Scott Smith · Harvard, US

Key dates

• Filing date: Feb 26, 1996
• Grant date: Jun 24, 1997
• Expiry date: Feb 26, 2016

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S414/141
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

A measurement station which rotates a wafer in a vertical plane and moves a scanning sensor linearly along an axis which is parallel to the wafer rotation plane, thus providing a spiral, or other, scan path across the wafer. The vertical orientation reduces errors from weight induced sagging, especially of large, e.g. 300 mm wafers. The measurement station includes wafer grippers which move in the wafer's plane for securing the wafer in position for rotation. The measurement station also includes master calibration gauges which simplify calibration and obviate the need for calibration test wafers. A technique for reducing vibration and assuring scan repeatability includes coasting of the wafer in rotation and coordinated linear probe motions for scanning. Probe measurement data obtained is digitized early and calibration, demodulation, filtering and other processing is done digitally.