The sensitivity and the resolution are affected by not only the nature of the resist such as a chemical structure and a molecular weight but also the developing process such as a developer molecular size. Exposure characteristics of positive-tone polymer resists having various molecular weights (Mw’s) ranging from 60 k to 500 k are investigated using different ester solvents as a developer. The line-and-space (L/S) patterns are exposed by the electron beam writing system with an acceleration voltage of 50 kV and the samples are developed by amyl acetate, hexyl acetate and heptyl acetate. The pattern shape becomes better and the surface of the resist also becomes smoother with increasing developer molecular size, though the exposure dose required for the formation of the L/S pattern increases. The dose margin of pattern formation is also wider in all the resists having the different molecular weights. The dissolution in the unexposed portions of the 60k-Mw resist for heptyl acetate is reduced significantly compared with those for amyl acetate and hexyl acetate. The improvement of the pattern shape and the increasing of dose margin are remarkable in the low molecular weight resist. The 3σ of line width roughness tends to be smaller in the higher molecular weight resist and with the larger molecular size developer. Exposure experiment of the 35 nm pitch pattern using the 500k-Mw resist developed at the room temperature is presented.

Date Published: 10 May 2016
PDF: 6 pages
Proc. SPIE 9984, Photomask Japan 2016: XXIII Symposium on Photomask and Next-Generation Lithography Mask Technology, 99840L (10 May 2016); doi: 10.1117/12.2240296

Published in SPIE Proceedings Vol. 9984:
Photomask Japan 2016: XXIII Symposium on Photomask and Next-Generation Lithography Mask Technology
Nobuyuki Yoshioka, Editor(s)