Atomistic simulation of silicon bombardment by energetic CF3+: product distributions and energies

We present an analysis of results obtained from molecular dynamics simulati ons of continuous bombardment of the Si surface with CF3+ ions at normal in cidence in the energy (E-i) range of 25-200 eV. Our analysis is aimed at un derstanding how the distributions in products and their kinetic energies de pend on E-i. As E-i increases, the product distribution is shifted toward a lower average molecular weight, and with atomic F and molecular CF becomin g the most common product species at the higher incident energies. These fi ndings agree well with recent experimental results. The kinetic energy dist ributions of the products are sensitive to E-i only in that the high-energy tail of the distribution becomes more prevalent with increasing E-i. Linea r cascade theory predictions agree reasonably well with our kinetic energy distributions. Individual species product kinetic energy distributions are much more sensitive to E-i, and primarily reflect that most high-energy pro ducts are of low molecular weight. The product kinetic energy as a function of ejection angle is also sensitive to E-i, displaying an increasing maxim um value with increasing E-i. These results could potentially help in the g uidance and interpretation of molecular beam experiments which seek to dete ct products in simulated fluorocarbon plasma etching of silicon. (C) 2000 E lsevier Science S.A. All rights reserved.