A new method to increase the doping efficiency of proton implantation in a high-dose regime

Besides the application of local lifetime control, proton implantations can be used to create deep donor profiles in crystalline silicon. At a certain annealing temperature, the maximum hydrogen-related donor (HD) concentration is limited to a few 1015 1/cm³ in the end-of-range depth of the radiation damage profile. This behavior is explained with a passivation of the shallow donors due to an excess supply of hydrogen at high proton doses. The impact of hydrogen remaining in the substrate from prior processing steps is investigated. As a countermeasure to the over-decoration effect, a pre-annealing step at elevated temperatures is investigated. This procedure is fully applicable in a commercial manufacturing environment. Experimental results from spreading resistance measurements are shown that clearly show the beneficial effect of the pre-conditioning. DLTS results of pre-conditioned samples are reported, that show a dominant deep defect level that was previously assigned to be vacancy related.