A Reliable Technology for Advanced SiC-MOS Devices Based on Fabrication of High Quality Silicon Oxide Layers by Converting a-Si

Abstract

An alternative technological approach is proposed to obtain a SiO2 film on SiC using processes that finally reduce the effective fabrication costs. Accordingly, we report achieving of a high-quality oxide on 4H-SiC substrate using a process flow that consists in a preliminary deposition by sputtering, at room temperature, of an amorphous Si thin layer, followed by its oxidation at a relative low temperature (1100 °C) for SiC MOS technology. The X-ray reflectivity measurements demonstrated that the resulted oxide has a comparable roughness with the one thermally grown and presents the advantage of an almost threefold thinner interfacial layer. The improvement of the oxide/semiconductor interface was further validated by the electrical investigation of the fabricated MOS structures, where a significant diminishing of the effective oxide charge density, interface traps density, and near interface oxide traps density was assessed. Thus, we demonstrated that, for a specified thickness of the oxide layer on SiC, the proposed technological flow not only significantly reduces the standard duration of the process necessary and consequently the associated fabrication cost, but, more important, leads to superior oxides and interfaces, in terms of both micro-physical and electrical properties.

Keywords

• Interface traps
• MOS
• near interface oxide traps
• oxidized amorphous silicon
• SiC