Deep etching of n-type 6H - SiC using a
two-step etching process has been studied. First, anodization of 6H - SiC in
an HF electrolyte (2 wt.%) without ultraviolet light is applied to form a deep
porous layer with the desired dimensions. Then, a thermal oxidation process is
used to oxidize this porous layer. The oxidized layer is then removed in a
concentrated HF solution. In the experiments, the etching parameters
electrolyte concentration and current density are optimized in order to obtain
a uniform pore size and hence, a smooth etched surface. After adjusting these
parameters, the porous layer formation experiments are carried out at 20°C in a
2 wt.% HF electrolyte using a current density of 50 mA/cm 2 . The
corresponding porous layer formation rate is about 1.1 μm/min. To demonstrate
the capabilities of this SiC bulk micromachining process, deep
circular cavities are fabricated in n-type 6H - SiCsubstrates.
Source:IEEE
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