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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
