AVS 52nd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThM

Paper PS-ThM5
Decomposition Mechanisms of 193 nm Photoresist under Ar+ and Radical Bombardment

Thursday, November 3, 2005, 9:40 am, Room 304

Session: Plasma-Surface Interactions II
Presenter: E. Pargon, University of California at Berkeley
Authors: E. Pargon, University of California at Berkeley
D. Nest, University of California at Berkeley
D.B. Graves, University of California at Berkeley
G.S. Oehrlien, University of Maryland
S. Engelmann, University of Maryland
X. Hua, University of Maryland
Y.C. Bae, Rohm and Haas Electronic Materials, L.L.C.
E.A. Hudson, Lam Research Corporation
Correspondent: Click to Email
193 nm methacrylate-based photoresists are known for their limited etch resistance and enhanced surface roughening compared to 248 nm photoresist. In this study, we examine the decomposition mechanisms of three 193 nm methacrylate-based photoresist formulations in a vacuum beam experiment. The vacuum beam system allows separate control of incident ionic and neutral radical species, more controlled exposure protocols and direct detection of etch products. The results obtained in the beam experiment are compared to complementary and analogous measurements made in a plasma etch environment. Photoresist samples are exposed to an Ar+ ion beam (100 eV - 1000 eV) and various radical beams. The species leaving the surface are detected in an in-situ threshold ionization quadrupole mass spectrometer. Film thickness and mass change are monitored during and after beam exposure. FTIR is used in transmission mode to detect changes in film structure after beam exposure. The primary volatile species leaving the room temperature photoresist surface during Ar+ ion bombardment are CO and H2O, with significant quantities of CO2 and C2H2 also detected. Volatile species initially leave the surface at a higher rate, and the initial etch rate is significantly higher than the average etch rate. FTIR measurements after beam exposure show that the most significant changes occur in the CH2 and CH3 stretching modes (3000 cm-1), although other changes in the carbonyl region (1700 cm-1) are observed as well. We report the effects of beam exposure on surface roughness as measured by ex-situ AFM. The impact of surface temperature and various radical fluxes (H, N and O) on decomposition rate and product distribution will also be reported.