Amorphous silicon (a-Si) was investigated as a potential masking material at 157nm wavelength. Characterization of a-Si included film deposition on CaF2 (calcium fluoride) substrates through reactive sputtering, spectroscopic ellipsometry in the UV range, reflection and transmission at 157nm wavelength, and extraction of optical constants (n&k) with a commercial software package. Experimental results suggest that a-Si films deposited at RIT have similar optical constants as published values in the UV range. Simulation work suggests that a 50A silicon nitride film can be used as an anti-reflective layer to minimize reflections at the a-Si I air boundary. Consequently, silicon nitride films were also investigated in this work. Since these films (stack) must be patterned for mask applications, proper dry etch selectivity among these materials must be achieved.
"Amorphous Silicon for 157nm Lithography,"
Journal of the Microelectronic Engineering Conference: Vol. 9
, Article 3.
Available at: http://scholarworks.rit.edu/ritamec/vol9/iss1/3