Method to Characterize the Stability of a Step and Repeat Lithographic System
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
The first order overlay parameters of photorepeater array generation as a function of X, Y table position have been studied. The estimated parameters are found to fluctuate against either row or column position of the X, Y table. The fluctuations represent influences of higher order overlay parameters not included in the current overlay model; thus, they point out some precautions to be exercised in the estimation the first order overlay parameters. The experimental procedure used in this study offers a simple and useful way to study the photorepeater overlay characteristics using small dimensional measurement data and to make two-dimensional standard containing angular information. The overlay performance of a lithographic system has to be strictly controlled in order to manufacture high performance VLSI circuits.