Chemical sputtering yields of silicon resulting from F+, CFn+ (n = 1,2,3) ion bombardment

Abstract

Chemical sputtering yields of crystalline silicon resulting from mass-separated, reactive ion bombardments are measured as a function of ion kinetic energy at room temperature. Ions of F+ and CFn+ (n = 1,2,3) are bombarded independently onto a silicon surface in an ultrahigh vacuum (UHV) environment. Evolution rate of SiF4 molecules resulting from surface chemical reaction: Si+4F→SiF4↑, is measured using a quadrupole mass filter. For F+/Si ion bombardment, yield increases monotonically with ion kinetic energy and saturates at 1 keV giving a value of 0.18. For CFn+/Si ion bombardment, yields show maxima at 1200 eV (CF+), 800 eV (CF2+) and 700 eV (CF3+). At ion energy ranges above 1.5 keV, yields for CFn+/Si are about half that for F+/Si. Carbon deposition and scavenging effects are discussed in detail by relating with fluorocarbon ion bombardment.