Development of a Storage Getter Test for Cu Contaminations in Silicon Wafers Based on ToF-SIMS Measurements

D. Kota, b, G. Kissingera, b, A. Sattlerc and T. Müllerc aIHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany bBTU Cottbus, Joint Lab IHP/BTU, Konrad-Wachsmann-Allee 1, D-03046 Cottbus, Germany cSiltronic AG, Hanns-Seidel-Platz 4, 81737 München, Germany

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This work presents development and results of a storage getter test based on the measurement of the metal concentration by time-of-flight secondary ion mass spectroscopy applied for a low Cu contamination level. It was found that Cu atoms introduced into the as-grown sample by a drive-in anneal at high temperature diffuse out from the bulk to the surface within 7 days of storage at room temperature. Annealing steps at low temperature should decrease the time which Cu needs for the outdiffusion to the surface. However, the Cu atoms in samples subjected to outdiffusion annealing at 250°C or 400°C precipitated in the bulk. The investigation of the getter efficiency by the storage test in silicon samples containing oxygen precipitates has shown that in order to achieve a getter efficiency above 90%, the density of bulk microdefects should be higher than 6 × 109 cm-3.

DOI: 10.12693/APhysPolA.125.965