Evaluation of AIM overlay mark for thin film head application

Yi Li; Alan Fan; Gary Etheridge; Gerald Finken; Darrel Louder

doi:10.1117/12.712332

5 April 2007 Evaluation of AIM overlay mark for thin film head application

Yi Li, Alan Fan, Gary Etheridge, Gerald Finken, Darrel Louder

Proceedings Volume 6518, Metrology, Inspection, and Process Control for Microlithography XXI; 65182W (2007) https://doi.org/10.1117/12.712332
Event: SPIE Advanced Lithography, 2007, San Jose, California, United States

Abstract

Overlay control becomes more crucial for wafer processing in thin film head (TFH) industry with continuous shrinkage in Critical Dimension (CD) in order to achieve higher data storage capacity. High topographic feature and thick transparent oxide between two overlay layers are unique challenges for TFH overlay measurement. It is important to know if overlay target represents the true overlay and its effect on overlay control. In this work, three overlay marks, Box-in-Box (BiB), Frame-in-Frame (FiF) and KLA-Tencor Advanced Imaging Metrology (AIM), were evaluated under different process conditions. The performance study of the overlay marks included following tests: overlay precision, Tool Induced Shift (TIS) variability and Total Measurement Uncertainty (TMU); effect of photo resist thickness and transparent oxide spacing between two overlay layers; overlay mark fidelity (OMF) from array test; analysis of stepper correctable terms residuals. It was found that AIM marks provided better metrology tool performance than BiB and FiF in terms of precision, TIS variability and TMU. It was also found that precision and TIS variability were sensitive to photo resist thickness and oxide thickness. Smaller overlay residual error was achieved using AIM target and OMF could be improved too.

Citation Download Citation

Yi Li, Alan Fan, Gary Etheridge, Gerald Finken, and Darrel Louder "Evaluation of AIM overlay mark for thin film head application", Proc. SPIE 6518, Metrology, Inspection, and Process Control for Microlithography XXI, 65182W (5 April 2007); https://doi.org/10.1117/12.712332

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