Apparent and real transient effects in SIMS depth profiling using oxygen bombardment

Sputter depth profiling in combination with secondary ion mass spectrometry (SIMS) suffers from a specific type of artefact that is intimately related to the use of oxygen (and caesium) primary ions as a means of enhancing the ionisation probability of sputtered atoms and molecules. Recent developments in the field are discussed. Particular attention is devoted to results obtained by sub-keV bombardment of boron doped silicon. It is shown that bulk doped calibration standards of nominally uniform concentration exhibit near-surface irregularities that can give rise to significant calibration errors. The areal density of shallow delta markers grown by molecular beam epitaxy may also vary across the wafer and between markers. First attempts are described that may lead to relatively simple procedures for correcting the dopant yield variations during the transient period.