MONITORING OF HEAVY-METALS IN AS-IMPLANTED SIMOX WITH SURFACE PHOTOVOLTAGE

Heavy metals in concentrations of E-16-E-18 cm-3 are commonly found in SIMOX samples implanted in high current implanters (100 mA). In the present study, surface photovoltage (SPV) was used successfully to measure the heavy metal concentration in as-implanted SIMOX. An initial correlation has been established between the minority carrier diffusion length measured on the back of a SIMOX wafer and Fe concentration measured by SIMS and spark source mass spectrometry in as-implanted SIMOX films. A correlation between the leakage current of MOS transistors and the heavy metal contamination level as measured by SPV was established. SPV measurements are quick, nondestructive, and do not require any additional sample preparation. They can therefore be used as a QC method to monitor heavy metals in as-implanted SIMOX layers. © 1990, The Electrochemical Society, Inc. All rights reserved.