High non-additive sputtering of silicon as large positive cluster ions under polyatomic ion bombardment

In the present work comparative studies of relative yields and mass spectra of secondary cluster Si-n(+) ions (n = 1-17) and carbon-containing cluster SinC+ (n = 1-12) and SinC2+ (n = 1-6) ions sputtered from a silicon target by atomic and polyatomic Au-m(-) projectiles (m = 1-3) with energy of 9 and 18 keV have been carried out. Anomalously high non-additivity in silicon sputtering as large positive cluster ions under polyatomic ion bombardment has been found. On the basis of the results obtained, a new method of "cluster-SIMS-cluster" registration of impurities in materials under study is proposed. This method makes it possible to increase the element analysis sensitivity more than three orders of a magnitude as compared to traditional SIMS methods. (C) 2000 Elsevier Science Ltd. All rights reserved.