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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.