Competition between internal and heavy doping gettering options in epi-silicon

By studying the competition between internal and p+ gettering, it was possible to identify the unwanted contaminant and estimate its concentration in unintentionally contaminated Si epi-structures simultaneously submitted to both gettering options. The contaminant concentration in the thermally untreated samples was below the DLTS detectability limit. Stratigraphic DLTS on thermally treated samples and EBIC study of the internal gettering allowed to establish that the contaminant was Fe. The occurrence of internal gettering even in presence of p+ gettering in p/p+ epi-structures suggested that the initial Fe concentration could have been in the range ∼1.5×109-5.2×1010 cm−3. Internal gettering is effective in p+ substrate because of the low onset temperature of p+ gettering.