Secondary Ion Yield Changes in Si and GaAs Due to Topography Changes During Ion Bombardment

Changes in secondary ion yield of matrix and dopant species have been correlated with changes in surface topography during O2+ bombardment of Si and GaAs. In Si, profiles were measured in (100) and (111) wafers at 6 keV impact energy. A yield increase of about 50% occurred for Si+ in (100) silicon over a depth range of 2.5 to 3.5 micron with corresponding changes in other matrix species. A smaller increased was noted in the B+ signal for a bulk doped wafers The development of a rippled surface topography was observed in scanning electron micrographs over the same depth range. Similar effects occurred in (111) silicon at a depth of 3 to 4 micron. No differences were noted between p and n-type silicon, or implanted and unimplanted silicon.