| Summary: | Approved for public release; distribution is unllimited === The sputtering process has been investigated by simulating the sputtering of single-crystal copper with 1=7 keV argon. A digital computer was used to build the crystal, bombard it, and move crystal atoms. Four mechanisms were observed which cause surface atoms to sputter. An atom is sputtered when (1) it is squeezed out of the surface, (2) it is scooped out when another atom strikes its inner hemisphere, (3) it is ejected when an atom passes behind it, and (4) it is knocked out by a second layer atom which is moving outward. Nearly all sputtered atoms were surface atoms. Second and third layer atoms were sputtered only for energies greater than 5 keV. They were sputtered by mechanisms similar to the surface atom mechanisms. "Sillsbee chains" were observed to be directed into the crystal, and momentum focusing was observed to cause spsuttering only when it occurred in close packed, surface rows. Outward directed chains were not observed. Sputtering deposit patterns, sputtering ratios, and sputtered atom energy distributions were obtained for (100), (110), and (111) surfaces. All data compared favorably with experimental data.
|
|---|
