Planarization of SiC and GaN Wafers Using Polishing Technique Utilizing Catalyst Surface Reaction

Catalyst-referred etching (CARE) is an abrasive-free chemical polishing method utilizing a catalytic chemical reaction at the contact points of a wafer and a catalyst plate surface. In contrast to conventional chemical mechanical polishing methods, in principle, it does not leave a subsurface damage layer on the processed surface because no abrasive is used. Using a platinum plate catalyst and hydrogen fluoride aqueous solution, an atomically flat 4H-SiC (0001) surface was obtained. Using only water and platinum, an atomically flat GaN (0001) surface was also obtained. The planarized surfaces have the features of smaller characteristic variation of Schottky barrier diode fabricated on the surface, higher photoluminescence intensity, and lower roughness of subsequent epitaxial growth. Furthermore, wafer-level polishing and methods for increasing the removal rate are described.