Thin silicon epitaxial layers on preannealed silicon substrates

Multistep-temperature pretreatment is used to create defect denuded zones at surfaces in conjunction with bulk defects in oxygen rich substrate wafers. Using structural etching, RF–CV measurements, EBIC investigations, and gamma spectroscopy it is shown that bulk defects act as sinks for metallic impurities being fixed at an early stage of bipolar technology, already Etchable defects induced due to subsequent processing steps – e.g., emerging from bulk regions and entering denuded zones – contain less metallic impurities. 2 μm epitaxial layers deposited on such substrates with bulk defects and denuded zones reveal excellent structural and electrical properties.