Carbon concentration measurement in silicon down to 1014 cm‐3: second generation IR, SIMS, CPAA and standardization

Abstract

AbstractCarbon concentration ([C]) measurement down to 1×1014 cm‐3 was examined by infrared absorption spectroscopy (IR), secondary ion mass spectroscopy (SIMS) and charged particle activation analysis (CPAA). In IR, the reference problem and the phonon problem were solved. By electron irradiation, substitutional carbon Cs was converted to IR insensitive interstitial carbon Ci. A reference with [C] of about 1×1014 cm‐3 which was accurately estimated was produced. Dip and protrusion around the carbon absorption line in the [C] 1014 cm‐3 range were identified and a way to cancel them was established. These techniques were transferred to many silicon crystal vendors, IR machine vendors and measurement service companies. SIMS and CPAA measurements were done on the samples measured by IR. The cross calibration was done at [C] = 5×1014 cm‐3 and is continued down to 1×1014 cm‐3. Electron irradiation to completely remove Cs provides the ideal reference containing effectively no carbon, a new technique to measure the absolute carbon content, and a standard sample for calibration of SIMS and CPAA. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)