Trace-Element Accelerator Mass Spectrometry: A New Technique for Low-Level Impurity Measurements in Semiconductors

Abstract

AbstractSIMS is a well-established technique for the measurement of impurities in semiconductor materials. It is the technique of choice for the measurement of very low levels of impurities, especially depth profiles. Accelerator Mass Spectrometry (AMS) is also a well-established technique and is primarily used for measurements of abundance ratios of long-lived radionuclides, such as 14C and 36C1 to their respective stable isotopes. A combination of these techniques holds the potential for impurity determination in semiconductors at the ppt level. The new technique, Trace- Element Accelerator Mass Spectrometry (TEAMS), eliminates the problem of molecular interference which is the major constraint limiting the sensitivity of SIMS. Depth profiles for B, P and As implants in Si, obtained by TEAMS are presented below.