Printing small vias with tight pitches is becoming very challenging and consequently, different techniques are explored to achieve a robust and stable process. These techniques include reverse tone imaging (RTI) process, source optimization, mask transmission (attenuated Phase Shift Masks (attnPSM) versus binary thin OMOG masks), three-dimensional mask effects models, and SRAF printing models. Simulations of NILS, MEEF, DoF and process variability (PV) band width across a wide range of patterns are used to compare these different techniques in addition to the experimental process window. The results show that the most significant benefits can be gained by using attnPSM masks in conjunction with source optimization and RTI process. However, this improvement alone is not enough; every facet of the computational lithography and process must be finely tuned to produce sufficient imaging quality. As technology continues to shrink, Electromagnetic Field (EMF)-induced errors limit the scalability of this process and we will discuss the need for advanced techniques to suppress and correct for them.

Date Published: 12 April 2013
PDF: 12 pages
Proc. SPIE 8683, Optical Microlithography XXVI, 86830J (12 April 2013); doi: 10.1117/12.2011349

Published in SPIE Proceedings Vol. 8683:
Optical Microlithography XXVI
Will Conley, Editor(s)