HIGH-RESOLUTION AUGER SPUTTER PROFILING STUDY OF EFFECT OF PHOSPHORUS PILEUP ON SI-SIO2 INTERFACE MORPHOLOGY

We have used Auger electron spectroscopy in conjunction with sputter etching and crater-edge profiling to study the distribution of phosphorus near the Si-SiO//2 interface and the effect of the phosphorus distribution on the width of the interface transition region. The samples studied consisted of thermal oxides approximately 1000-A-thick grown on Si (111) substrates with initial phosphorus concentrations up to 6 multiplied by 10**2**0 cm** minus **3. Phosphorus pileup at the Si-SiO//2 interface was observed with the phosphorus peak (after correcting for electron escape depth effects) on the Si side within 5 A of the interface. The 10%-90% width of the Si-SiO//2 transition region as measured by the Si//L//V//V transition varies from 25 (low doping limit) to 38 A (bulk doping level of 6 multiplied by 10**2**0 cm** minus **3). Results are interpreted in terms of a recently proposed model for the Si-SiO//2 interface.