SEMICONDUCTOR TECHNOLOGY

A novel oxidation-based wet etching method for AlGaN/GaN heterostructures

Jinbao Cai, Jinyan Wang, Yang Liu, Zhe Xu, Maojun Wang, Min Yu, Bing Xie and Wengang Wu

+ Author Affiliations

 Corresponding author: Cai Jinbao, Email:jywang@ime.pku.edu.cn; Wang Jinyan, caijinbaoxd@126.com

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Abstract: A novel wet etching method for AlGaN/GaN heterojunction structures is proposed using thermal oxidation followed by wet etching in KOH solution. It is found that an AlGaN/GaN heterostructure after high temperature oxidation above 700℃ could be etched off in a homothermal (70℃) KOH solution while the KOH solution had no etching effects on the region of the AlGaN/GaN heterostructure protected by a SiO2 layer during the oxidation process. A groove structure with 150 nm step depth on an AlGaN/GaN heterostructure was formed after 8 h thermal oxidation at 900℃ followed by 30 min treatment in 70℃ KOH solution. As the oxidation time increases, the etching depth approaches saturation and the roughness of the etched surface becomes much better. The physical mechanism of this phenomenon is also discussed.

Key words: AlGaN/GaNwet etchingthermal oxidationKOH solution



[1]
Hao Y, Yang L, Ma X. High-performance microwave gate-recessed AlGaN/AlN/GaN MOS-HEMT with 73% power-added efficiency. Electron Device Lett, 2011, 32(5):626 doi: 10.1109/LED.2011.2118736
[2]
Regan S K, Milosavljevic I D. Electron velocity enhancement in laterally scaled GaN DH-HEMTs with ft of 260 GHz. Electron Device Lett, 2011, 32(8):1074 doi: 10.1109/LED.2011.2158386
[3]
Rowena I B, Selvaraj S L, Egawa T. Buffer thickness contribution to suppress vertical leakage current with high breakdown field (2.3 MV/cm) for GaN on Si. Electron Device Lett, 2011, 32(11):1534 doi: 10.1109/LED.2011.2166052
[4]
Buttari D, Heikman S, Keller S. Digital etching for highly reproducible low damage gate recessing on AlGaN/GaN HEMTs. IEEE Lester Eastman Conference on High Performance Devices, 2002:461
[5]
Vartuli C B, Pearton S J, Abernathy C R. Wet chemical etching survey of Ⅲ-nitrides. Solid-State Electron, 1997, 41(12):1947 doi: 10.1016/S0038-1101(97)00173-1
[6]
Ko C H, Su Y K, Chang S J. Photo-enhanced chemical wet etching of GaN. Mater Sci Eng B, 2002, 96(1):43 doi: 10.1016/S0921-5107(02)00323-9
[7]
Huang Shengrong, Chen Chao. Research and progress of wet etching for GaN. Micronanotechnology, 2005, 42(6):272
[8]
Adessida I, Mahajan A, Andideh E. Reactive ion etching of gallium nitride in silicon tetrachloride plasmas. Appl Phys Lett, 1993, 63(20):2777 doi: 10.1063/1.110331
[9]
Shul R J, McClellan G B, Casalnuovo S A. Inductively coupled plasma etching of GaN. Appl Phys Lett, 1996, 69(8):1119 doi: 10.1063/1.117077
[10]
Ping A T, Adesida I, Khan M A. Study of chemically assisted ion beam etching of GaN using HCl gas. Appl Phys Lett, 1995, 67(9):1250 doi: 10.1063/1.114387
[11]
Kawakami R, Inaoka T, Minamoto S. Analysis of GaN etching damage by capacitively coupled RF Ar plasma exposure. Thin Solid Films, 2008, 516(11):3478 doi: 10.1016/j.tsf.2007.08.019
[12]
Kim H. Reactive ion etching damage in n-GaN and its recovery by post-etch treatment. Electronics Lett, 2008, 44(17):1037 doi: 10.1049/el:20081771
[13]
Lanford W B, Tanaka T, Otoki Y. Recessed-gate enhancement-mode GaN HEMT with high threshold voltage. Electronics Lett, 2005, 41(7):449 doi: 10.1049/el:20050161
[14]
Wolter S D, Luther B P, Waltemyer. X-ray photoelectron spectroscopy and X-ray diffraction study of the thermal oxide on gallium nitride. Appl Phys Lett, 1997, 70(16):2156 doi: 10.1063/1.118944
[15]
Masato H, Ikeda Y, Matsuno T. Novel high drain breakdown voltage AlGaN/GaN HFETs using selective thermal oxidation process. IEDM Technical Digest International, 2000:377
[16]
Roccaforte F, Giannazzo F, Iucolano F. Electrical behavior of AlGaN/GaN heterostructures upon high-temperature selective oxidation. J Appl Phys, 2009, 106:023703 doi: 10.1063/1.3174438
[17]
Lee H Y, Huang X Y, Lee C T. Light output enhancement of GaN-based roughened LEDs using bias-assisted photoelectrochemical etching method. J Electrochem Soc, 2008, 155(10):H707
Fig. 1.  A plot of the groove's step heights and average roughness $R_{\rm a}$ of the wafer's wet-etched area versus oxidation time (line with quadrilateral symbol refers to step height and triangle symbol to $R_{\rm a}$).

Fig. 2.  The 3D image of the groove structure with 8 h oxidation time.

Fig. 3.  TEM high resolution image of the AlGaN/GaN heterojunction structure after thermal oxidation at 900 for 30 min.

Fig. 4.  Oxygen element distribution in the oxidation AlGaN/GaN heterojunction.

Fig. 5.  TEM high resolution image of the AlGaN/GaN heterojunction structure after thermal oxidation at 900 for 30 min followed by treatment in KOH solution.

Fig. 6.  Cross profile of the AlGaN/GaN heterojunction structure after thermal oxidation at 900 for 30 min followed by treatment in KOH solution.

[1]
Hao Y, Yang L, Ma X. High-performance microwave gate-recessed AlGaN/AlN/GaN MOS-HEMT with 73% power-added efficiency. Electron Device Lett, 2011, 32(5):626 doi: 10.1109/LED.2011.2118736
[2]
Regan S K, Milosavljevic I D. Electron velocity enhancement in laterally scaled GaN DH-HEMTs with ft of 260 GHz. Electron Device Lett, 2011, 32(8):1074 doi: 10.1109/LED.2011.2158386
[3]
Rowena I B, Selvaraj S L, Egawa T. Buffer thickness contribution to suppress vertical leakage current with high breakdown field (2.3 MV/cm) for GaN on Si. Electron Device Lett, 2011, 32(11):1534 doi: 10.1109/LED.2011.2166052
[4]
Buttari D, Heikman S, Keller S. Digital etching for highly reproducible low damage gate recessing on AlGaN/GaN HEMTs. IEEE Lester Eastman Conference on High Performance Devices, 2002:461
[5]
Vartuli C B, Pearton S J, Abernathy C R. Wet chemical etching survey of Ⅲ-nitrides. Solid-State Electron, 1997, 41(12):1947 doi: 10.1016/S0038-1101(97)00173-1
[6]
Ko C H, Su Y K, Chang S J. Photo-enhanced chemical wet etching of GaN. Mater Sci Eng B, 2002, 96(1):43 doi: 10.1016/S0921-5107(02)00323-9
[7]
Huang Shengrong, Chen Chao. Research and progress of wet etching for GaN. Micronanotechnology, 2005, 42(6):272
[8]
Adessida I, Mahajan A, Andideh E. Reactive ion etching of gallium nitride in silicon tetrachloride plasmas. Appl Phys Lett, 1993, 63(20):2777 doi: 10.1063/1.110331
[9]
Shul R J, McClellan G B, Casalnuovo S A. Inductively coupled plasma etching of GaN. Appl Phys Lett, 1996, 69(8):1119 doi: 10.1063/1.117077
[10]
Ping A T, Adesida I, Khan M A. Study of chemically assisted ion beam etching of GaN using HCl gas. Appl Phys Lett, 1995, 67(9):1250 doi: 10.1063/1.114387
[11]
Kawakami R, Inaoka T, Minamoto S. Analysis of GaN etching damage by capacitively coupled RF Ar plasma exposure. Thin Solid Films, 2008, 516(11):3478 doi: 10.1016/j.tsf.2007.08.019
[12]
Kim H. Reactive ion etching damage in n-GaN and its recovery by post-etch treatment. Electronics Lett, 2008, 44(17):1037 doi: 10.1049/el:20081771
[13]
Lanford W B, Tanaka T, Otoki Y. Recessed-gate enhancement-mode GaN HEMT with high threshold voltage. Electronics Lett, 2005, 41(7):449 doi: 10.1049/el:20050161
[14]
Wolter S D, Luther B P, Waltemyer. X-ray photoelectron spectroscopy and X-ray diffraction study of the thermal oxide on gallium nitride. Appl Phys Lett, 1997, 70(16):2156 doi: 10.1063/1.118944
[15]
Masato H, Ikeda Y, Matsuno T. Novel high drain breakdown voltage AlGaN/GaN HFETs using selective thermal oxidation process. IEDM Technical Digest International, 2000:377
[16]
Roccaforte F, Giannazzo F, Iucolano F. Electrical behavior of AlGaN/GaN heterostructures upon high-temperature selective oxidation. J Appl Phys, 2009, 106:023703 doi: 10.1063/1.3174438
[17]
Lee H Y, Huang X Y, Lee C T. Light output enhancement of GaN-based roughened LEDs using bias-assisted photoelectrochemical etching method. J Electrochem Soc, 2008, 155(10):H707
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    Received: 08 January 2013 Revised: 26 January 2013 Online: Published: 01 August 2013

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      Jinbao Cai, Jinyan Wang, Yang Liu, Zhe Xu, Maojun Wang, Min Yu, Bing Xie, Wengang Wu. A novel oxidation-based wet etching method for AlGaN/GaN heterostructures[J]. Journal of Semiconductors, 2013, 34(8): 086004. doi: 10.1088/1674-4926/34/8/086004 J B Cai, J Y Wang, Y Liu, Z Xu, M J Wang, M Yu, B Xie, W G Wu. A novel oxidation-based wet etching method for AlGaN/GaN heterostructures[J]. J. Semicond., 2013, 34(8): 086004. doi: 10.1088/1674-4926/34/8/086004.Export: BibTex EndNote
      Citation:
      Jinbao Cai, Jinyan Wang, Yang Liu, Zhe Xu, Maojun Wang, Min Yu, Bing Xie, Wengang Wu. A novel oxidation-based wet etching method for AlGaN/GaN heterostructures[J]. Journal of Semiconductors, 2013, 34(8): 086004. doi: 10.1088/1674-4926/34/8/086004

      J B Cai, J Y Wang, Y Liu, Z Xu, M J Wang, M Yu, B Xie, W G Wu. A novel oxidation-based wet etching method for AlGaN/GaN heterostructures[J]. J. Semicond., 2013, 34(8): 086004. doi: 10.1088/1674-4926/34/8/086004.
      Export: BibTex EndNote

      A novel oxidation-based wet etching method for AlGaN/GaN heterostructures

      doi: 10.1088/1674-4926/34/8/086004
      Funds:

      the National Natural Science Foundation of China 60736033

      the National Natural Science Foundation of China 60406004

      Project supported by the National Natural Science Foundation of China (Nos. 60406004, 60890193, 60736033) and the National Key Micrometer/Nanometer Processing Laboratory, China

      the National Natural Science Foundation of China 60890193

      the National Key Micrometer/Nanometer Processing Laboratory, China. 

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      • Corresponding author: Cai Jinbao, Email:jywang@ime.pku.edu.cn; Wang Jinyan, caijinbaoxd@126.com
      • Received Date: 2013-01-08
      • Revised Date: 2013-01-26
      • Published Date: 2013-08-01

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