Surface Cleaning and Etching of 4H-SiC(0001) Using High-Density Atmospheric Pressure Hydrogen Plasma

Abstract

We propose low-damage and high-efficiency treatment of 4H-SiC(0001) surfaces using atmospheric pressure (AP) hydrogen plasma. Hydrogen radicals generated by the AP plasma was found to effectively remove damaged layers on SiC wafers and improve surface morphology by isotropic etching. Localized high-density AP plasma generated with a cylindrical rotary electrode provides a high etching rate of 1.6 microm/min and yields smooth morphology by eliminating surface corrugation and scratches introduced by wafer slicing and lapping procedures. However, high-rate etching with localized plasma was found to cause an inhomogeneous etching profile depending on the plasma density and re-growth of the poly-Si layer at the downstream due to the decomposition of the vaporized SiH(x) products. On the other hand, for the purpose of achieving moderate etching and ideal cleaning of SiC surfaces, we demonstrated the application of a novel porous carbon electrode to form delocalized and uniform AP plasma over 4 inches in diameter. We obtained a reasonably moderate etching rate of 0.1 microm/min and succeeded in fabricating damage-free SiC surfaces.

Fundamental Aspects of Silicon Carbide Oxidation

“…This indicates formation of a near-perfect SiO 2 /SiC interface and coincides well with a recent report based on high-resolution medium energy ion scattering [9]. As previously reported, ideal hydrogen passivation of a SiC surface with a diluted HF solution was barely obtained, and the initial sample surface after wet cleaning was partially oxidized and contaminated with adsorbates [18]. This implies that a chemical shift component of C 1s core-level spectra involves unavoidable signals due to surface contamination.…”

Synchrotron Radiation Photoelectron Spectroscopy Study of Thermally Grown Oxides on 4H-SiC(0001) Si-Face and (000-1) C-Face Substrates

“…This indicates formation of a near-perfect SiO 2 /SiC interface from a physical analysis point of view. As previously reported, ideal hydrogen passivation of the SiC surface with a HF solution was barely obtained, and the initial sample surface after wet cleaning was partially oxidized and contaminated with adsorbates [17]. This implies that a chemical shift component of C 1s core-level spectra involves unavoidable signals due to surface contamination.…”

Silicon Carbide Wafer Machining by Using a Single Filament Plasma at Atmospheric Pressure

“…One major method for SiC machining using DBD uses the ionizing wave injected by the plasma generating gas flow on to the SiC surface [28][29][30][31]. Another DBD using method is direct discharge SiC machining, in which the SiC substrate acts as one of the DBD plasma generating electrodes, making direct contact with the processing plasma [32][33][34][35][36][37]. Since these methods can effectively control the etching width, depth, and volume removal rate, it can be a suitable tool for correction machining, which removes the part deviating from the target shape after an elemental process.…”