Reduce Probability of Wafer Intra-Field Process (Printing) Defects for Logic & DRAM Applications

Authors

Yael Sufrina, Avi Cohena, Ofir Sharonia, Rolf Seltmannb
aCarl Zeiss SMT GmbH, Hadolev 3 Bar Lev Industrial Park, Misgav, Israel
bExternal Consultant

Abstract

Wafer Intra-Field Process (Printing) Defects can be cause from various process topics.

Narrow Lithography process window (Litho PW), effected by Dose & Focus (calibrated by FEM – Focus Exposure Matrix), is one of the major contributors to the wafer intra-filed process defects cause by hot spots.

The Litho PW can be expand by controlling the Dose parameter over the wafer intra-field. Dose parameter effects the Critical Dimension Uniformity (CDU).
Controlling the wafer intra-field CDU will expand the Litho PW and reduce the process (printing) defects.

The extension of 193nm based lithography usage combined with design rule shrinkage makes process control, in particular the wafer level CDU control, an extremely important and challenging task in IC manufacturing.

This work will show the ZEISS CDC application (CD Control) effect on the intra-field CDU, Litho PW, and process defects probability, and the flow integration in the wafer fab. It will also challenge process parameters spec and will explain IC failures can happen where all process parameters are at the edge of spec distribution and each individual parameter is in spec since it is nearly impossible to check all possible interdependencies among different parameters. The goal is to remove the extremes of the distributions even if parameter variability is in specification.
This work will offer solution named by Excursion Prevention – Improve wafer intra-field CDU using the ZEISS CDC tool, to reduce the wafer intra-field printing defects cause by narrow Litho PW.

Keywords: DUV, Lithography, CDU, CDC, Process printing Defects, Excursion Prevention, wafer Intra-Field

Proceedings Volume 11177, 35th European Mask and Lithogrpahy Conference (EMLC 2019); 1117712 (2019) https://doi.org/10.1117/12.2535686
Event: 35th European Mask and Lithography Conference, 2019, Dresden, Germany