| Abstract |
Object of this work was the use of Scanning Acoustic Microscopy (SAM) to identify and characterise defects in power semiconductor devices, particularly in p-i-n diodes, bipolar junction transistors (BJT), silicon controlled rectifiers (SCR), and gate turn-off thyristors (GTO). Defects like impurities in the crystal, microcracking in the silicon wafer, voids at the silicon/metallisation interface, are inevitably introduced at various stages of the manufacturing process, and these strongly affect the electrical performance of the device. Since high voltage and current ratings are required from very large area devices, an accurate knowledge of the defects introduced during processing is a key factor for obtaining reasonable yields in manufacturing. SAM was seen as a candidate non-destructive technique for the identification at an early stage in the fabrication process of defects that may affect the electrical performance of the device. This paper reports the results obtained during a two years research project, carried out under the auspices of the European Community's BRITE Programme, whose aim was the development of non-destructive test methods for on-line process monitoring of high power semiconductor device manufacture. |
