플라즈마 조성, ICP source power, rf chuck power 등의 공정변수가 GaN epitaxy층의 식각특성에 미치는 영향을 조사하였다. $GaF_x$ 화합물 보다 더 높은 휘발성을 가지는 $GaCl_x$ 식각 생성물 형성이 가능한 $Cl_2/Ar$ 플라즈마가 $SF_6/Ar$ 플라즈마보다 더 높은 식각속도를 나타내었다. 또한, $Cl_2/Ar$ 플라즈마에서 Ar 비중이 증가함에 따라 물리적 식각 기구 활성화로 인해 식각 이방성이 향상됨을 확인하였다. 두 가지 플라즈마 조성 모두에서 ICP source power와 rf chuck power가 증가함에 따라 식각속도가 지속적으로 증가함을 확인하였고, $13Cl_2/2Ar$, 750W ICP power, 400 W rf chuck power, 10 mTorr 조건에서 최고 251.9 nm/min의 식각속도를 확보하였다.
The effect of process parameters such as plasma composition, ICP (Inductively Coupled Plasma) source power and rf chuck power on the etch characteristics of GaN epitaxy layer was studied. $Cl_2/Ar$ ICP discharges showed higher etch rates than $SF_6/Ar$ discharges because of the higher volatility of $GaCl_x$ etch products than $GaF_x$ compounds. As the Ar ratio increases in the $Cl_2/Ar$ ICP discharges, the etch anisotropy was enhanced due to the improved physical component of the etching. For both plasma chemistries, the GaN etch rate increased continuously as both the ICP source power and rf chuck power increased, and a maximum etch rate of 251.9 nm/min was obtained at $13Cl_2/2Ar$, 750W ICP power, 400W rf chuck power and 10 mTorr condition.
Y.C. Chiang, C.C. Lin and H.C. Kuo, "Novel thin-GaN LED structure adopted micro abraded surface to compare with conventional vertical LEDs in ultraviolet light", Nanoscale Res. Lett. 10 (2015) 182.
D. Steigerwald, S. Rudaz, H. Liu, R.S. Kern, W. Gotz and R. Fletcher, "III-V nitride semiconductors for highperformance blue and green light-emitting device", JOM 49 (1997) 18.
D. Zhu and C.J. Humphreys, "Low-cost high-efficiency GaN LED on large-area Si substrate", CS MANTECH Conference, May, New Orleans, USA (2013).
E.J. Kang, C. Huh, S.H. Lee, J.J. Jung, S.J. Lee and S.J. Park, "Improvement in light-output power of InGaN/GaN LED by formation of nanosize cavities on p-GaN surface", Electrochem. Solid-State Lett. 8 (2005) G327.
J.B. Shim and Y.K. Lee, "Growth and characterization of bulk GaN single crystals by basic ammonothermal method", J. Korean Cryst. Growth Cryst. Technol. 26 (2016) 58.
T. Uesugi and T. Kachi, "GaN power switching devices for automotive applications", CS MANTECH Conference, May, Tempa, USA (2009).
M.A. Briere, "The status of GaN-on-Si based power device development at international rectifier", Applied Power Electronics Conference Exhibitor Presentation, March, Long Beach, USA (2013).
M. Cho and Y.D. Koo, "Commercialization and research trends of next generation power devices SiC/GaN", J. Energy Eng. 22 (2013) 58.
H. Cho, K.H. Auh, J. Han, R.J. Shul, S.M. Donovan, C.R. Abernathy, E.S. Lambers, F. Ren and S.J. Pearton, "UV-photoassisted etching of GaN in KOH", J. Electronic Mater. 28 (1999) 290.
R.J. Shul, C.B. McCellan, R.D. Briggs, D.J. Rieger, S.J. Pearton, C.R. Abernathy, J.W. Lee, C. Constantine and C. Barratt, "High-density plasma etching of compound semiconductors", J. Vac. Sci. Technol. A 15 (1997) 633.
Y.P. Hong, J.H. Park, C.W. Park, H.M. Kim, D.K. Oh, B.G. Choi, S.K. Lee and K.B. Shim, "Investigation of defects and surface polarity in AlN and GaN using wet chemcal etching technique", J. Korean Cryst. Growth Cryst. Technol. 24 (2014) 196.