Abstract

In mask-alignment systems a reference signal is needed to align the mask with the silicon wafers. The optical reference signal is the autocorrelation of two two-dimensional (2D) codes with binary transmittance. For a long time, one-dimensional codes have been used in grating-measurement systems to obtain a reference signal. The design of this type of code has needed a great computational effort, which limits the size of the code to about 100 elements. Recently, we have applied genetic algorithms to design codes with arbitrary length. We propose the application of these algorithms to design 2D codes to generate 2D optical signals used in mask-alignment systems.

© 2006 Optical Society of America

Optimal design of optical reference signals by use of a genetic algorithm

José Saez-Landete, Sancho Salcedo-Sanz, Manuel Rosa-Zurera, José Alonso, and Eusebio Bernabeu
Opt. Lett. 30(20) 2724-2726 (2005)

Design of two-dimensional zero reference codes with cross-entropy method

Jung-Chieh Chen and Chao-Kai Wen
Appl. Opt. 49(18) 3560-3565 (2010)

Design of two-dimensional zero reference codes by means of a global optimization method

José Saez-Landete, José Alonso, and Eusebio Bernabeu
Opt. Express 13(11) 4230-4236 (2005)

Design of zero reference codes by means of a global optimization method

José Saez-Landete, José Alonso, and Eusebio Bernabeu
Opt. Express 13(1) 195-201 (2005)

Design of zero reference codes using cross-entropy method

Jung-Chieh Chen
Opt. Express 17(24) 22163-22170 (2009)