C–V profiling of ultra-shallow junctions using step-like background profiles

A novel C–V profiling method that enables profiling of ultra-shallow and ultra-abrupt junctions is described. The method takes advantage of a peculiar shape of the C–V characteristic that is obtained with a step-like or some other abruptly changing background profile. The method is theoretically described and confirmed by MEDICI simulations. Experimental use of the method requires the fabrication of both a p–n and a Schottky diode with identical background profiles. Here, a step-like background As profile and an ultra-shallow and ultra-abrupt p+ junction were achieved by Si epitaxy and pure boron RPCVD, respectively. Using these techniques, junctions with a doping depth of around 7 nm and with a slope of about 2.5 nm/dec were fabricated and measured. The way to create an optimal experimental situation in terms of measurement range and accuracy is discussed.