Photoelectrochemical Etching of 6 H  ‐ SiC

Abstract

A new photoelectrochemical etching process is described for n-type 6H-SiC, while dark electrochemistry has been used to pattern p-type material. In this two-step etching process, the SiC is first anodized to form a deep porous layer, and this layer is subsequently removed by thermal oxidation followed by an HF dip. Etch rates as high as 4000 A/min for n-SiC and 2.2 ~m/min for p-SiC have been obtained during the anodization, resulting in near mirror-like etched surfaces.

Photoelectrochemistry of 4H–SiC in KOH solutions

“…Such current-potential characteristics are typical for passivation of a semiconductor, such as Si whose oxide is partly soluble in the electrolyte solution [20]. In contrast, voltammetric measurements on n-type 6H-SiC in HF solutions do not show such passivation characteristics; the current density instead reaches a limiting value [9]. This implies that the oxide is more soluble in HF solution than in KOH solution.…”

“…Shor and coworkers have carried out an extensive study of the photoelectrochemistry of SiC (b-SiC, 6H-SiC) in acidic fluoride solution [7][8][9]. The p-type material could be etched anodically in the dark [9].…”

“…The p-type material could be etched anodically in the dark [9]. Photoanodic dissolution was observed for n-type material [10].…”

Morphological and photoluminescence study of porous thin SiC layer grown onto silicon

“…It has been suggested that the dissolution of SiC involves the oxidation of SiC, and dissolution of the formed oxide as shown below [8,9] :…”

“…[9,10] Formation of carbon dioxide (CO 2 ) and carbon monoxide (CO) bubbles have Considering that the anodic etching of SiC in aqueous HF also produces stable (SiF 6 ) 2− ions, we believe the following reactions also can take place [11] :…”