Scanning infrared microscopy study of thermal processing induced defects in low resistivity Si wafers

Abstract

Scanning infrared microscopy (SIRM) is used to study thermal processing induced oxygen precipitation in low resistivity n+ and p+ Si substrates doped with As, P, Sb or B. It is shown that SIRM allows us to investigate successfully Si samples with resistivities as low as 1.7 mΩ cm and to measure non-destructively bulk micro spectroscopy densities between 107 and 1010 cm−3 with precipitate sizes as small as 30 nm. Comparison with precipitation in moderate resistivity reference material that received the same thermal treatments reveals a strong impact of doping for concentrations above 5 × 1018 cm−3, in particular, in combination with rapid thermal processing pre-treatments at temperatures above 1000 °C. The observations can be understood by intrinsic point defect trapping during rapid thermal processing and release during subsequent lower temperature treatments through its impact on homogeneous oxide precipitate nucleation.