Micro-Raman evaluation of 200 mm SiC material

Abstract

The study and evaluation of 4H-SiC 200 mm substrates has revealed an increase of defect density that is generated by the seed expansion. Defects disappeared in 150 mm substrates have to be faced again in 200 mm like polytype inclusions, bar shaped defects and carbon inclusions. They must be suppressed being the root of extended and detrimental defects on epitaxial layer.Raman analysis reveals presence of polytype inclusions (6H or 15R). Also, the monitoring of the TO Raman mode along the whole wafer suggest an additional stress on the material and reduced crystallographic quality.The detection of carbon inclusions suggests a crystallographic quality that has to be improved. An extensive study of the material is in progress to better define the quality of the substrates and provide suitable suggestion to improve the crystal growth.