A STUDY OF BORON-DIFFUSION IN HEAVILY-DOPED SILICON

The boron diffusion in heavily doped silicon was studied using directly bonded silicon samples. In directly bonded samples between heavily doped and lightly doped silicon, an enhanced exponential tail of the diffusion profile was observed. This phenomenon is proposed to be attributed to the mobile interstitial boron and silicon interstitial complexes originated from the heavily doped silicon. Because a formation of these complexes occurs via an interaction between positively charged silicon interstitials and ionized boron, the silicon interstitial concentration in silicon heavily doped with boron is saturated. This hypothesis is substantiated by the fact that the retrogrowth rate of oxidation-induced stacking faults in silicon heavily doped with boron is much slower than in a lightly doped silicon.