Integrated model for plasma CVD and etch processes

Abstract

Simulating the complex interactive phenomena in plasma CVD and etch reactors is an exceedingly daunting task because of the wide range of time and space scales that naturally occur in such reactors. The models required will depend on the pressure regime of the reactor. Deposition reactors employ pressures ranging from 10's of Torr to 100's of Torr and are collisional while etch reactors range from fractions of a milliTorr (transitional/collisionless) to several Torr (borderline collisional). In a microwave diamond CVD diffusion reactor operating at 40 Torr, time scales range from 10/sup -9/ s for the time required to establish the microwave electric field to /spl sim/1 s for the system throughput time. Spatial scales range from /spl sim/10/sup -3/ cm for the Debye length to fractions of a meter for the reactor dimension. Of most interest generally is the steady state dynamics and chemistry that is established, typically on a millisecond or longer time scale. An integrated CVD model requires modules that simulate the electromagnetic field development, plasma physics including the nonthermal electron energy distribution, nonequilibrium gas chemistry, diffusion/convection, heat transport, and surface chemistry. We describe our progress in modeling these different plasma processes emphasizing the techniques required to put together an integrated and practical model that simulates the non-equilibrium steady state. The codes being integrated include: BMUSED-Boltzmann multispecies electron deposition, CHOCHEM-Automated chemistry integrator, CVDSIM-Navier-Stokes fluid code with thermal conductivity, DSMC-Direct Simulation Monte Carlo code for transition regime.