Etching End-Point Detector Employing Laser Interferometer and Video Display
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
In a semiconductor wafer-etching system laser interferometry is used to monitor the progress of the etching and determine the "end point" where etching should be discontinued. It is most usual to use a light detector system and the amplitude of the peaks and nulls which can be interpreted to determine the end point. In the system described herein, a color video camera and display are added to the optical system. Color changes can be observed in the display which help in determining the end point. As the wafer is being etched in the manufacturing operation, the video display is also used to assist in placing the laser illumination in the desired area. The figure shows a schematic diagram of the overall system.