Today we see that 248nm lithography is pushed to the region of very low k1-factors. The first 193nm systems are now on the market, but the technology needs still needs to mature before its optimum performance can be reached. On the other hand, development of 157nm systems has been started in order to push optical lithography to the 100nm and 70nm nodes. In this paper simulations are used to show how far optical lithography could be extended assuming mature tools and resists. The simulations are performed using Prolith/2 and Solid-C in combination with Monte Carlo calculations to predict ED-windows and CD control at 193nm and 157nm illumination. Different resolution enhancement techniques are invested for dense and isolated lines and contact holes: off-axis illumination, phase shifting masks and high NA settings. Once the optimum NA-sigma combinations for maximum process windows are determined, CD control is calculated by taking into account variations in focus, dose, reticle CD and phase and lens aberrations. From these CD control calculations the most important contributions to CD variations for the different RET can be identified, showing also where restrictions have to be put to obtain sufficient CD control.

Date Published: 5 July 2000
PDF: 15 pages
Proc. SPIE 4000, Optical Microlithography XIII, (5 July 2000); doi: 10.1117/12.389027

Published in SPIE Proceedings Vol. 4000:
Optical Microlithography XIII
Christopher J. Progler, Editor(s)