Formation of Ultra-Shallow and Low-Leakage pn Junction by Low-Temperature Annealing

摘要

It has been found that a defect which is considered to be a complex of a dopant in the substrate and point defects (interstitial/vacancy) are generated deeply in the substrate by ion implantation. In order to investigate this defect, MOS capacitors having several substrate dopant concentrations in both n--type and p-type were prepared. These MOS capacitors were Si~+ ion-impIanted to form the defects before electrode formation. As a result, it was found that the generation lifetime (T_g) of carriers of these MOS capacitors becomes smaller as the substrate dopant concentration increases for both substrate types. Also, it was found that T_g of boron-doped silicon is about one-order of magnitude smaller than that of phosphorus-doped silicon. From the temperature dependence of T_g, it was found that the energy level of this defect is located at the middle of the silicon band-gap for both substrate types.