Automatic Positioning System
Original Publication Date: 1978-Feb-01
Included in the Prior Art Database: 2005-Feb-20
One application of the system of U. S. Patent 3,957,376 (Fig. 1) is to measure the width of metal and quartz lines by shining a monochromatic light spot of approximately 0.004" diameter on the target line and by analyzing the resulting diffraction pattern in a computer. For this application, the target line must be isolated within the spot, i.e., the target line and only the target line must be inside the spot. Moreover, the measurement of complex overlay patterns located close to product chips dictates in extremely high accuracy requirement, e.g., of +/ 0.001". However, the present mechanical positioning technology is only good for a positioning accuracy of +/- 0.0035".