End Point Detector for Chemi-Mechanical Polisher
Original Publication Date: 1988-Sep-01
Included in the Prior Art Database: 2005-Feb-15
This article describes a technique for determining the end point for a polishing process when polishing a wafer. Fig. 1 shows a wafer holder and holder arm positioned above a wafer polishing table which rotates in the direction indicated during the polishing operation. The wafer holder also rotates and moves in and out in a regular fashion under control of the holder arm to make a wafer in the holder contact the spinning table. The friction between the spinning wafer and the table depends upon the material being polished. By monitoring the current to the motor driving the table, it can be determined when a particular layer has been removed and the material underneath it is being polished.