TY - JOUR
T1 - Selective electrochemical etching of epitaxial aluminum nitride thin film
AU - Choi, Yongha
AU - Choi, Rakjun
AU - Kim, Jihyun
N1 - Funding Information:
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) ( 20173010012970 and 20172010104830 ) and National Research Foundation of Korea ( NRF-2018R1D1A1A09083917 ).
Publisher Copyright:
© 2020
PY - 2020/4/15
Y1 - 2020/4/15
N2 - Aluminum nitride (AlN) has an ultra-wide bandgap energy of 6.2 eV and is resistant to chemical etching owing to its high chemical stability, making it intractable in the device fabrication process. We developed a facile method of electrochemical (EC) etching of a high-quality AlN epitaxial layer, where both spatial selectivity and a controllable etch rate were achieved. Underneath porous metal electrodes, the lateral etch rate increased with the increasing external anodic bias, from 400 nm/min at 5 V to 700 nm/min at 15 V. Nonporous metal electrodes protected the AlN from etching in hot H3PO4, enabling the spatial selectivity. The high EC etch rate is attributed to the enhanced hole-assisted oxidation at the interface between the AlN and the etchant. The etch pit formed by EC etching exhibited an inverse hexagonal pyramid structure with {1 0 –1 −1} face. As an alternative to dry etching, our method can be applied to the low-damage patterning of AlN with a controllable etch rate.
AB - Aluminum nitride (AlN) has an ultra-wide bandgap energy of 6.2 eV and is resistant to chemical etching owing to its high chemical stability, making it intractable in the device fabrication process. We developed a facile method of electrochemical (EC) etching of a high-quality AlN epitaxial layer, where both spatial selectivity and a controllable etch rate were achieved. Underneath porous metal electrodes, the lateral etch rate increased with the increasing external anodic bias, from 400 nm/min at 5 V to 700 nm/min at 15 V. Nonporous metal electrodes protected the AlN from etching in hot H3PO4, enabling the spatial selectivity. The high EC etch rate is attributed to the enhanced hole-assisted oxidation at the interface between the AlN and the etchant. The etch pit formed by EC etching exhibited an inverse hexagonal pyramid structure with {1 0 –1 −1} face. As an alternative to dry etching, our method can be applied to the low-damage patterning of AlN with a controllable etch rate.
KW - Aluminum nitride
KW - Electrochemical etching
UR - http://www.scopus.com/inward/record.url?scp=85078178691&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2020.145279
DO - 10.1016/j.apsusc.2020.145279
M3 - Article
AN - SCOPUS:85078178691
SN - 0169-4332
VL - 509
JO - Applied Surface Science
JF - Applied Surface Science
M1 - 145279
ER -