Plasma assisted remediation of SiC surfaces

Abstract

This paper describes a three-step process to remediate surface and sub-surface defects on chemo-mechanically polished SiC surfaces. In this process, a CF4-based inductively coupled plasma with reactive ion etch was used to remove material to a depth, which is unaffected by surface and subsurface polishing damage. This produced a planarized but carbon-rich fluorinated surface. This surface was then exposed to a 2 min rapid thermal oxidation in air at 1000 °C to oxidize and volatilize the excess carbon and fluorinated species, respectively. The resulting surface oxide was then stripped using a dilute hydrofluoric acid in water solution. This process, referred to as plasma assisted remediation, reproducibly yielded planarized, stoichiometric surfaces with low levels of carbon and oxygen contamination suitable for subsequent device fabrication. In the supporting studies described here, 4H- and 6H-SiC(0001) surfaces were remediated and characterized by x-ray photoelectron spectroscopy and atomic force microscopy at each stage of the process. Experimental studies under ion-rich and radical-dominant conditions are also reported which provide greater insight into the underlying chemistry and physics of the process.