Boron Gettering by Fluorine in Ion Implanted Silicon

Abstract

ABSTRACTSi was implanted with fluorine and boron ions. Boron gettering by fluorine was studied. By varying the implantation energy of F+ ions, three types of samples were made in which Rp(F)<Rp(B), Rp(F)∼Rp(B) and Rp(F)>Rp(B). There are three special regions in which the redistribution of Boron atoms during annealing differ. The first one is the near surface region in which the Boron concentration exceeds the value of Boron solid solubility at the annealing temperature. In this region, B atoms are intensively redistributed and have two peaks of concentration. The positions of these peaks coincide with the position of the peaks on the fluorine concentration profile. In the second specific region, the boron concentration is less than the value of solid solubility in Si and higher than the value of the intrinsic carrier concentration in Si at the annealing temperature. In this region, the B concentration was identical in all samples, and it exponentially decreased to the value of 5×108 cm−3. The slope of the boron concentration in the third region dictates the depth of p-n junction. A possible mechanism of boron gettering by fluorine is discussed.