Automatic feedback control to optimize stepper overlay

Mark Drew Jr.; Kevin G. Kemp

doi:10.1117/12.148965

4 August 1993 Automatic feedback control to optimize stepper overlay

Mark Drew Jr., Kevin G. Kemp

Proceedings Volume 1926, Integrated Circuit Metrology, Inspection, and Process Control VII; (1993) https://doi.org/10.1117/12.148965
Event: SPIE'S 1993 Symposium on Microlithography, 1993, San Jose, CA, United States

Abstract

Systematic offset errors can be a major contributor to total overlay error on projection wafer steppers. To compensate for this offset error we have developed an automated method using measured overlay results from previous lots to generate offset correction values for current lots. This method provides statistically optimized offset corrections while eliminating the need to process test wafers. In addition the dynamic correction capability of the feedback control loop automatically compensates for offset changes such as drift in stepper alignment systems, process modification, and mask revisions. The system has been in use for over a year and has proven extremely effective in eliminating systematic offset errors on numerous devices.

Citation Download Citation

Mark Drew Jr. and Kevin G. Kemp "Automatic feedback control to optimize stepper overlay", Proc. SPIE 1926, Integrated Circuit Metrology, Inspection, and Process Control VII, (4 August 1993); https://doi.org/10.1117/12.148965

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