Atomic and cluster ion emission from silicon in secondary-ion mass spectrometry. Pt. 1

Using the dynamic SIMS mode (i.e., a sputtering rate of some nm s-1), we have carried out a survey of the Sisub(n) and Sisub(n)Osub(r) secondary ions of mass up to 300 u produced on bombardment of doped Si wafers by argon or oxygen ions, both under high vacuum (<= 10-5 Pa) and with oxygen gas introduced into the target chamber. The primary ion energies for positive and negative ions were 5.5 and 14.5 keV, respectively. With an adequate supply of oxygen, the cluster ions show especially stable forms for Sisub(n)O+2sub(n)sub(-)2, Sisub(n)O+2sub(n)sub(-)1 (n > 2) and Sisub(n)O-2sub(n), Sisub(n)O-2sub(n)sub(+)1. A comparison of static SIMS data and measurements on SiO2 with the present results shows, for oxygen admission up to saturation of the Si+ signal, excellent agreement both for the species of cluster ions observed and their intensities. (orig.)