TEAMS DEPTH PROFILES IN SEMICONDUCTORS

Accelerator Mass Spectrometry (AMS) is routinely used to measure abund ance ratios of long-lived radioisotopes such as C-14, Cl-36 and I-129 to their stable isotopes at levels as low as 1 x 10(-15), Secondary Io n Mass Spectrometry (SIMS) is one of the most sensitive techniques for the determination of impurity depth profiles in semiconductors, Trace Element Accelerator Mass Spectrometry (TEAMS) is the combination of t hese two techniques, applied to the measurement of very low levels of stable elements in a matrix that may be quite different from the eleme nt being detected, TEAMS offers the possibility of detection limits of the order of tens of ppt for certain impurities in silicon, which is substantially better than SIMS. In general TEAMS data is subject to th e same constraints as SIMS, the big improvement arising from the elimi nation of molecular interferences which bedevil SIMS, The IBMAL at Uni versity of North Texas (UNT) has a dedicated facility for TEAMS measur ements. A detailed description of the laboratory and TEAMS apparatus w ill be presented along with recent TEAMS depth profiles from a variety of implantations in semiconductors.