Design and implementation of a multifunctional 'golden standard' wafer which facilitates easy and rapid measurement of the most important optical stepper parameters using commercially available metrology tools and software are described. In this design a stepped array of reference marks is permanently etched into a silicon oxide film on a silicon wafer. The most important feature of this method is that a permanently etched pattern is used as a reference standard, which may be used to compare a number of steppers over a period of time. When it is required to perform a distortion measurement the wafer is simply coated with photoresist and a series of full-field exposures are exposed on the stepper to be measured. Using this method, the errors due to individual stepper stages are removed since each lens distortion measurement is made with respect to a common grid pattern. Furthermore this method provides useful information regarding the accuracy of the stepper alignment system. In addition the permanent alignment marks on the wafer permit the measurement of individual stepper stage matching, as well as stage orthogonality errors.

Date Published: 1 July 1991
PDF: 7 pages
Proc. SPIE 1464, Integrated Circuit Metrology, Inspection, and Process Control V, (1 July 1991); doi: 10.1117/12.44440

Published in SPIE Proceedings Vol. 1464:
Integrated Circuit Metrology, Inspection, and Process Control V
William H. Arnold, Editor(s)