Mounting table for wafers

US4583847A · kind A · utility

Inventors

• Udo Battig · Hermsdorf, DE
• Peter Dittrich · Jena, DE
• Norbert Oertel · Landshut, DE
• Gunter Osterland · Hermsdorf, DE
• Mathias Rucknagel · Hermsdorf, DE
• Werner Scheler · Jena, DE
• Klaus Schultz · Jena, DE

Key dates

• Filing date: Jul 16, 1984
• Grant date: Apr 22, 1986
• Expiry date: Jul 16, 2004

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L21/681
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The invention relates to an improvement for a wafer mounting table particularly for use in photolithographic apparatus for processing wafers comprising a compact mounting block made of glass-ceramics which has two neighboring back supports limiting two sides of a top face of said mounting block. The top face is provided with at least three studs for supporting a wafer to be processed. The sides of the back-supports facing away from said top face are provided with an elongated horizontally extending silvered area each, which is in opposition to a laser path measuring system each. The laser beams of said laser path measuring system define a plane which coincides with a projection plane of a projection lens being provided in opposition to a wafer mounted on said studs. Means are provided for substantially eliminating departures of the silvered areas from a straight plane. Further means are provided which enable a quick adaption of the laser mount for wafer charges having different thicknesses or diameters.