ArF immersion lithography has reached mass production stage for 55-40 nm node devices. Especially, defectivity performance at wafer edge in immersion lithography has been recently discussed in detail, because its controllability is a key factor to obtain high yield. We have already reported that defectivity was strongly affected by the wafer edge shape and long edge wafer showed better defectivity performance than short one. We also found remaining flakes or particles at wafer edge after coating were easy to be peeled off on short edge wafer during exposure and these peeled flakes or particles were most suspected candidate which induces bridging defects. Therefore it is important to prevent generating such peeled flakes or particles for good defectivity in immersion lithography. In this paper, we will show the defectivity results of various kinds of wafers which have different wafer edge shapes (long,short and full-round) and diameters to investigate the effect of wafer edge geometry on defectivity performance in detail. Furthermore, we investigated the relation of an edge removal method and the defectivity with referring bevel inspection results at each coating step. We confirmed that the modified edge removal method well improved the defectivity performance. We will discuss them based on the latest data and propose the most suitable technique to remove the wafer edge particles before immersion exposure.

Date Published: 16 March 2009
PDF: 10 pages
Proc. SPIE 7274, Optical Microlithography XXII, 72741G (16 March 2009); doi: 10.1117/12.813385

Published in SPIE Proceedings Vol. 7274:
Optical Microlithography XXII
Harry J. Levinson; Mircea V. Dusa, Editor(s)