Quantitative evaluation of in-plane deformation due to mask holding in x-ray lithography
Abstract
We report the evaluation of tool-holding deformation using the displacement between the X-ray mask pattern and the pattern replicated on a wafer. The origins of the displacement between the mask and replicated pattern are wafer-holding deformation, run-out, thermal effect and mask-holding deformation. To estimate in-plane deformation (IPD) due to wafer holding, we develop a numerical method, where conservation of distance along a neutral plane is taken into consideration. Using this method, the displacement between the mask and replicated pattern becomes free of IPD due to the difference in wafer out-of-plane deformation (OPD). We also evaluate run-out and thermal effect using two kinds of masks with high and low absorber coverage, and obtained run-out values of 1.7 nm/micrometers horizontally and 2.8 nm/micrometers vertically. The residual displacement equals IPD due to mask holding on the exposure tool after eliminating the IPD due to wafer holding, run- out and thermal effect. We apply these procedures to the following two masks: Si substrates adhered to a frame along the entire periphery and those adhered to frame at one point. IPD due to mask holding with one- point adhesion is not observed within the accuracy of the analysis.
- Publication:
-
Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing V
- Pub Date:
- May 1995
- DOI:
- 10.1117/12.209155
- Bibcode:
- 1995SPIE.2437..151H