High-efficiency planarization of GaN wafer by catalyst-referred etching with positive-biased photo-electrochemical oxidation

摘要

Ununiformity of the removal rate in PEC-CARE is caused by the oxidation rate fluctuation due to the donor concentration difference. We proposed a positively biased PEC-CARE named BPEC-CARE to suppress the fluctuation. In the case that the donor concentration is not so high such as lower than 1x10~(18) cm~(-3), the removal rate fluctuation could be completely suppressed. However, in the case that the donor concentration is higher, the depletion layer could not be expanded sufficiently, and the removal rate of the BPEC-CARE still fluctuates. To solve this problem, we attempt to reduce the penetration depth of UV light by employing shorter wavelength UV light.