Growth of SiC bulk crystals for application in power electronic devices – process design, 2D and 3D X‐ray in situ visualization and advanced doping

Abstract

Silicon carbide single crystals have become widely used as substrates for power electronic devices like diodes and electronic switches. Today, 4inch and 6inch wafer diameters are commercially available which are processed from vapor grown crystals. The state of the art physical vapor transport method may be called mature. Nevertheless, low defect density and uniform doping are still topics which can be further improved by current research and development of more sophisticated processes and process control. The aim of the paper is to review the physical vapor transport growth method as applied today. Special emphasis will be put on currently less advanced in situ growth monitoring tools based on 2D and 3D X-ray imaging that could be a tool for production monitoring. These techniques allow a precise determination of the crystal and source material evolution. Another topic will be the processing of highly conductive p-type 4H-SiC which is of particular interest for power electronic switches

Analysis of the Basal Plane Dislocation Density and Thermomechanical Stress during 100 mm PVT Growth of 4H-SiC

“…Bulk silicon carbide (SiC) grown using the physical vapor transport (PVT) growth method has been established as a new material for high performance power electronic devices [1,2]. To achieve high device performance it is essential to understand defect generation during crystal growth.…”

Influence of the growth interface shape on the defect characteristics in the facet region of 4H-SiC single crystals

“…The growth process was monitored using our in-situ CT system [6]. The growth setup is imaged From the resulting crystals four wafers are cut from the curved crystal growth front close to the facet.…”

Solution Growth of Silicon Carbide Using the Vertical Bridgman Method

“…It is finished with a grit of 4000. This leads to a minimized surface wetting which we can visualize by in‐situ 3D computed tomography ( Figure ). The seed is fixed at the bottom of the crucible with carbon glue and then filled with electronic grade silicon granules resulting in a melt height of 1 cm at growth temperature.…”

“…Different SiC power switches are already available on the market . Commercial SiC‐wafer production is carried out by the physical vapor transport (PVT) method, also called seeded sublimation growth, where a SiC powder source is sublimated and recrystallized at a seed at temperatures above 2000 °C . Currently SiC wafers with a diameter of up to 6 inch are available and 8 inch prototypes were demonstrated already .…”