It was well established that low-energy B+ ion implantation into Ge- (or Si) implantation pre-amorphized Si allows ultra-shallow p+n junction formation. However, this process was known to generate defects such as dislocation loops, vacancies and interstitials which could act as vehicles to different mechanisms inducing electrically active levels into the Si bulk. The junctions studied were obtained using 3keV/1015/cm2 B+ implantation into Ge-implantation pre-amorphized substrates and into a reference crystalline substrate. Accurate measurements using deep level transient spectroscopy and isothermal transient capacitance were performed to characterize these levels. Such knowledge was crucial to improve the device characteristics. In order to sweep the Si band gap, various experimental conditions were considered. The analysis of deep level transient spectra have first showed three deep levels associated to secondary induced defects. Their concentration profiles were derived from isothermal transient capacitance at depths up to 3.5μm into the Si bulk and allowed the detection of a new deep level. The evolution of such defect distribution in correlation with the technological steps was described. The end of range defect influence on electrical activity of secondary induced defects in ultra-shallow p+n diodes was clearly demonstrated.

Deep Levels Induced by Low-Energy B+ Implantation into Ge Pre-Amorphized Silicon in Correlation with End-of-Range Formation. M.Benzohra, F.Olivie, M.Idrissi-Benzohra, K.Ketata, M.Ketata: Nuclear Instruments and Methods in Physics Research B, 2002, 187[2], 201-6