The strong influence of oxygen to the positive secondary ion yield determines the problems of SIMS depth profiling of shallow boron implants in silicon, related to surface oxide and formation of modified layer. High value (4 eV) of electron affinity of BO2 molecule responds for the high yield of BO2- negative secondary ions, its small sensitivity to the variation of emission properties of the sample surface and relatively weak dependence on oxygen concentration. The features of using of named ions for shallow boron profiling was studied with a magnetic sector SIMS instrument in a high mass resolution mode under O-2(-) and NO2- primary ion bombardment. The refuse from oxygen flooding allowed to avoid the initial significant change of sputter rate. The studied approach provides simplification of transient phenomena while still keeping sufficient sensitivity. (C) 2002 Elsevier Science B.V. All rights reserved.