Investigation of indium activation by C-V measurement

Due to low solid solubility and high ionization energy of indium in silicon, there are difficulties in characterizing indium activation under non-depletion conditions. In this study, SRP, SIMS, and pulsed C-V measurements were made on indium implanted wafers and the results compared. Samples were implanted at various energies ranging from 100 keV to 250 keV with doses ranging from 2×10¹² cm^-2 to 8×10¹² cm^-2. The implant was done through a 250 Å thermal oxide. Subsequent anneals were performed at 950°C for 10 sec in pure nitrogen ambient. The C-V analysis revealed indium activation levels up to 1.4×10¹⁸ cm^~3 in the case of 180 keV, 8×10¹² cm^-2 implant, although the profiling could not be completed due to avalanche breakdown. This concentration is close to the solid solubility limit of indium as reported before in the literature. In all cases C-V measurement detected higher activated doping concentration than SRP