To ensure successful mass production for GAA MBCFET structures and beyond, EUV overlay technology has advanced to withstand extreme process conditions. Commonly used method for its effectiveness was using overlay feedforward strategy to compensate upcoming critical layers such as ‘N+1’, or ‘N+2’ layer with current layer ‘N’ assuming the applied layers have kindred stack properties with identical overlay targets. Overlay feedforward strategy has been developed internally in great sophistication to significantly enhance on product overlay(OPO) proven also in mass production phase. However, it has been recognized that using aforementioned strategy to specific products rooting from GAA MBCFET structure may not be as beneficial as anticipated. In this paper, we would like to present the source of this strange phenomenon largely due to wafer warpage, in which we provide comprehensive solutions to measure, contain and permanently eradicate the originating in-coming process. After implementation of the authors' solution, overlay feedforward strategy demonstrated to be efficacious even for highly biased process excursions.
Optimal color weighting (OCW) is a promising technique to improve accuracy and robustness of alignment mark measurement in the lithography process. Measurement based OCW shows remarkable improvement of overlay error under laboratory conditions. In those conditions, one of the wafer processes is split and a simple form of mark deformation is present. However, the OCW effect has not been confirmed in the case of on-product overlay since various of deformations are mixed in the real FAB. We perform simple simulation showing that mixed deformations can deteriorate the performance of OCW and show that utilizing spatial characteristics of the wafer with OCW further improves the overlay error. As a result, we have improved on-product-overlay form 3.78 nm to 3.51 nm or 7.1% using data of 86 lots, 268 wafers in DUV layer of 3 nm logic device.
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.