Comparison of different analytical techniques in measuring the surface region of ultrashallow doping profiles

Abstract

Accurate knowledge of the dopant surface concentration of ultrashallow junctions is very important, especially since high surface concentrations are often encountered and these could have serious consequences on device performance. Our group has studied several different analytical techniques to understand the boron surface concentration of plasma-doped p+–n junctions that are about 60 nm deep. Secondary ion mass spectrometry has been performed with both oxygen and cesium primary ions. The O+2 secondary ion mass spectrometry was carried out both in vacuo and with an oxygen bleed to minimize surface ion yield transients. In addition, the surface boron concentration has been measured by resonance ionization mass spectrometry and Auger electron spectroscopy. Finally, the surface electrical carrier concentration of these p+–n junctions has been determined by spreading resistance profiling, differential Hall effect profiling, and microwave surface impedance profiling. A comparison of the surface results of these various measurement techniques will be presented and discussed in this article.