Measurement of short-range PSF in EBL

Abstract

Experimental measurement for Short Range (SR) part of PSF in EBL is essential for at least three reasons: Proximity effect correction, the study of the resolution limit of electron lithography, and characterizing the beam size of an EBL instrument. In this work, we introduce a measurement technique that is adequate for the above tasks with the purpose of evaluating its performance. Our approach is based on the following principles. We use a derivate of PSF – Line Spread Function (LSF) - because the latter is an extended object whose size can be averaged along its length during size measurement. Second, the use of thin negative resists like HSQ and PMMA operating in a negative tone avoids distortion due to lateral development. Third, the experimental check of normalization requirement validates the obtained PSFs. SR parts of PSFs in the range of 8–26 nm (FWHM) are accurately measured.

Keywords

• Electron beam lithography
• Point spread function