Contamination reduction for 150 mm SiC substrates by integrating CMP and Post-CMP cleaning

The quality of silicon carbide (SiC) substrates has great influence on the quality of the epitaxial layers atop. During the epitaxial growth, crystallographic defects and substrate contaminations may transform to various surface defects, such as carrots, polytype inclusions and scratches, which are detrimental to the performance and reliability of SiC devices. In general, chemical mechanical polishing (CMP) and post-CMP cleaning are the last two steps before the epitaxial growth, playing critical roles in controlling the scratch and contamination levels on the SiC substrates. In this article, the methods for reducing the aluminum (Al) and manganese (Mn) metal contaminations as well as other surface particle contaminations are investigated. We found that different commercial CMP slurries may lead to different contamination levels. Most importantly, by adding a scrubber cleaning step prior to the conventional RCA cleaning process, the contamination levels can be greatly reduced, achieving the quality for mass production.