Analysis of molecular diffusion in resist polymer films simulated by molecular dynamics

Minoru Toriumi; Takeshi Ohfuji; Masayuki Endo; Hiroaki Morimoto

doi:10.1117/12.350220

11 June 1999 Analysis of molecular diffusion in resist polymer films simulated by molecular dynamics

Minoru Toriumi, Takeshi Ohfuji, Masayuki Endo, Hiroaki Morimoto

Proceedings Volume 3678, Advances in Resist Technology and Processing XVI; (1999) https://doi.org/10.1117/12.350220
Event: Microlithography '99, 1999, Santa Clara, CA, United States

Abstract

The diffusion process of acids plays important roles in chemically amplified resists. Polymer matrices from the diffusion path, and the structure significantly influences the behavior of the acid diffusion. We have simulated the diffusions of molecules in polymer matrices by molecular dynamics in order to analyze the diffusion mechanism in chemically amplified resist syste. To represent bulk state conditions of the polymer film, we prepared the molecular structures under the 3D periodic boundary conditions utilizing the molecular simulation. This amorphous cell contained three chains of methacrylate polymers such as poly(methacrylate), poly(tert-butylmethacrylate), poly(isobornylmethacrylate) and one diffusion molecule such as oxygen and methanesulfonic acid. The structure was energy-minimized and equilibrated under stable conditions. The free volumes in the system were estimated as the volumes enclosed by the iso-potential surfaces around the polymer using the Gusev-Suter method. The average size of the free volumes in the poly(methylmethacrylate) system was obtained as 3.7 angstrom³ with large standard deviation of 11.1 angstrom³, which indicates the large width of the size- distribution of free volumes scattered at random in the system. Molecular diffusion in the energy-minimized cell was simulated for 50 picoseconds by the molecular dynamics. The time dependence of the mean-square displacements of diffusing molecules was obtained from the dynamics treatments and it determined the diffusion constant in the resist systems. It is shown that the molecules do not always rapidly diffuse with larger free volumes, but the diffusions also depend upon the interaction with the polymer, and that the computer simulation tools provide the potentia for the molecular level study of resists chemistry.

Citation Download Citation

Minoru Toriumi, Takeshi Ohfuji, Masayuki Endo, and Hiroaki Morimoto "Analysis of molecular diffusion in resist polymer films simulated by molecular dynamics", Proc. SPIE 3678, Advances in Resist Technology and Processing XVI, (11 June 1999); https://doi.org/10.1117/12.350220

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