Thermomechanical distortions of advanced optical reticles during exposure
- 25 June 1999
- proceedings article
- Published by SPIE-Intl Soc Optical Eng
- Vol. 3676, 756-767
- https://doi.org/10.1117/12.351144
Abstract
If optical lithography is to be extended into the 157 nm regime, controlling mask-related distortions will be a necessity. Thermomechanical distortions during exposure could be a major source of pattern placement error, especially if alternative materials such as CaF2 or MgF2 are employed. Full 3D finite element heat transfer and structural models have been developed to simulate the response of the reticle during both full-field and scanning exposure systems. Transient and periodic steady-state temperature distributions have been determined for typical exposure duty cycles. Corresponding in-plane and out-of- plane thermal distortions have been identified for both fused silica and calcium fluoride substrates. Under equivalent exposure conditions, the distortions in the CaF2 are significantly higher.This publication has 0 references indexed in Scilit: