Model etch profiles for ion energy distribution functions in an inductively coupled plasma reactor

Rectangular trench profiles are modeled with analytic etch rates determined from measured ion distribution functions. The pattern transfer step for th is plasma etch is for trilayer lithography. Argon and chlorine angular ion energy distribution functions measured by a spherical collector ring analyz er are fit to a sum of drifting Maxwellian velocity distribution functions with anisotropic temperatures. The fit of the model ion distribution functi ons by a simulated annealing optimization procedure converges adequately fo r only two drifting Maxwellians, The etch rates are proportional to analyti c expressions for the ion energy flux. Numerical computation of the etch pr ofiles by integration of the characteristic equations for profile points an d connection of the profiles points is efficient. (C) 1999 American Vacuum Society.