Study of Line Edge Roughness and Interactions of Secondary Electrons in Photoresists for EUV Lithography


Suchit Bhattarai

EECS Department
University of California, Berkeley
Technical Report No. UCB/EECS-2017-121
June 8, 2017

EUV lithography (EUVL) is a candidate technology for patterning of ever shrinking feature sizes in integrated circuits. There are several challenges to high volume manufacturing of devices using EUVL in a cost-effective manner, which include limited source power, mask defects and non-idealities in the photoresist, the imaging medium. Focus of this thesis is on photoresists. Specifically, influence of absorption shot noise on the final LER was studied experimentally through comparative analysis of LER obtained with EUV (92 eV photons) and 100 keV e-beam lithography. EUV is a form of ionizing radiation, therefore the most probable outcome of an absorption event the generation of secondary electrons, which then initiate chemistry that ultimately leads to pattern formation in the resist. Optimizing exposure efficiency therefore requires developing an understanding of energy delivery mechanisms. In this research, the energy delivery capacity of electrons at various energies ranging between 15 eV and 91 eV were also studied from both an experimental as well as theoretical standpoint.

Advisor: Andrew R. Neureuther

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