Anodic oxidn. appts. for silicon wafer - with tungsten wire reference electrode over wafer for controlled oxidn. of defect pn-junction

摘要

Appts. for the anodic oxidn. of a Si wafer, which is made the anode in a cell (1) filled with electrolyte and having a noble metal cathode, also has a W wire (5) as reference electrode, which is placed over the Si wafer (3) and pref. ca. 1 mm from this. Pref. the W wire is (partly) coated with oxide. The Si wafer is placed on a metal or graphite plate (2) and is parallel to a Pt cathode. The appts. is specified for use in the anodic oxidn. of Si wafers with defect pn-junctions. Defect pn-junctions and transistors with low breakdown voltage or high leakage current can be oxidised selectively.