Highly Sensitive and Accurate Infrared Absorption Measurement of Carbon Concentration in Si Crystal

摘要

Infrared absorption (IR) measurement of carbon concentration ([C]) in silicon crystal around 10~(15) cm~(-3) was examined. Measurement of 605 cm"1 absorption was difficult due to the overlapping double phonon peak. Absorption of C_iO_i complexes at 862 cm~(-1) induced by electron irradiation was a good measure of [C] below 10~(15) cm~(-3). Also, electron irradiation was successfully utilized to reduce the substitutional carbon concentration in the reference sample by nearly one order of magnitude. Second harmonic vibrational mode at 1206 cm"' was observed in samples with [C] down to 10~(16) cm~(-3). One mm thick samples and commercial wafers can be measured. Charged particle activation analysis was applied to samples with [C] around 10~(15) cm~(-3) and evaluated by IR.