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Comprehensive study of crystalline AlN/sapphire templates after high-temperature annealing with various sputtering conditions

Wen Gu1, 2, Zhibin Liu1, 2, 3, , Yanan Guo1, 2, 3, Xiaodong Wang1, 2, 3, Xiaolong Jia4, Xingfang Liu2, 5, Yiping Zeng4, 5, 6, Junxi Wang1, 2, 3, Jinmin Li1, 2, 3 and Jianchang Yan1, 2, 3,

+ Author Affiliations

 Corresponding author: Zhibin Liu, E-mail: yanjc@semi.ac.cn and zbliu@semi.ac.cn; Jianchang Yan, E-mail: yanjc@semi.ac.cn and zbliu@semi.ac.cn

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Abstract: High-quality AlN/sapphire templates were fabricated by the combination of sputtering and high-temperature (HT) annealing. The influence of sputtering parameters including nitrogen flux, radio frequency power, and substrate temperature on the crystalline quality and surface morphology of annealed AlN films were investigated. With lower substrate temperature, lower power, and lower N2 flux, the full width at half maximum of the X-ray rocking curve for AlN (0002) and (10$ \bar {1} $2) were improved to 97.2 and 259.2 arcsec after high-temperature annealing. This happens because the increased vacancy concentration of sputtered AlN films can facilitate the annihilation of dislocations by increasing the recovery rate during HT annealing. Step and step-bunching morphologies were clearly observed with optimized sputtering conditions.

Key words: sputterannealingAlNdislocation density



[1]
Li J M, Liu Z, Liu Z Q, et al. Advances and prospects in nitrides based light-emitting-diodes. J Semicond, 2016, 37, 061001 doi: 10.1088/1674-4926/37/6/061001
[2]
Wu Z H, Yan J C, Guo Y N, et al. Study of the morphology evolution of AlN grown on nano-patterned sapphire substrate. J Semicond, 2019, 40, 122803 doi: 10.1088/1674-4926/40/12/122803
[3]
Dong P, Yan J C, Zhang Y, et al. AlGaN-based deep ultraviolet light-emitting diodes grown on nano-patterned sapphire substrates with significant improvement in internal quantum efficiency. J Cryst Growth, 2014, 395, 9 doi: 10.1016/j.jcrysgro.2014.02.039
[4]
Ehrentraut D, Sitar Z. Advances in bulk crystal growth of AlN and GaN. MRS Bull, 2009, 34, 259 doi: 10.1557/mrs2009.76
[5]
Dalmau R, Moody B, Schlesser R, et al. Growth and characterization of AlN and AlGaN epitaxial films on AlN single crystal substrates. J Electrochem Soc, 2011, 158, H530 doi: 10.1149/1.3560527
[6]
Xu F J, Zhang L S, Xie N, et al. Realization of low dislocation density AlN on a small-coalescence-area nano-patterned sapphire substrate. CrystEngComm, 2019, 21, 2490 doi: 10.1039/C8CE01788C
[7]
Yan J C, Wang J X, Liu N X, et al. High quality AlGaN grown on a high temperature AIN template by MOCVD. J Semicond, 2009, 30, 103001 doi: 10.1088/1674-4926/30/10/103001
[8]
Yan J C, Wang J X, Zhang Y, et al. AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE. J Cryst Growth, 2015, 414, 254 doi: 10.1016/j.jcrysgro.2014.10.015
[9]
Chen X, Zhang Y, Yan J C, et al. Deep-ultraviolet stimulated emission from AlGaN/AlN multiple-quantum-wells on nano-patterned AlN/sapphire templates with reduced threshold power density. J Alloy Compd, 2017, 723, 192 doi: 10.1016/j.jallcom.2017.06.240
[10]
Dong P, Yan J C, Wang J X, et al. 282-nm AlGaN-based deep ultraviolet light-emitting diodes with improved performance on nano-patterned sapphire substrates. Appl Phys Lett, 2013, 102, 241113 doi: 10.1063/1.4812237
[11]
Chen X, Yan J C, Zhang Y, et al. Improved crystalline quality of AlN by epitaxial lateral overgrowth using two-phase growth method for deep-ultraviolet stimulated emission. IEEE Photonics J, 2016, 8, 1 doi: 10.1109/JPHOT.2016.2614102
[12]
Du Z J, Duan R F, Wei T B, et al. Producing deep UV-LEDs in high-yield MOVPE by improving AlN crystal quality with sputtered AlN nucleation layer. J Semicond, 2017, 38, 113003 doi: 10.1088/1674-4926/38/11/113003
[13]
Huang C, Wu P, Chang K, et al. High-quality and highly-transparent AlN template on annealed sputter-deposited AlN buffer layer for deep ultra-violet light-emitting diodes. AIP Adv, 2017, 7, 055110 doi: 10.1063/1.4983708
[14]
Susilo N, Hagedorn S, Jaeger D, et al. AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire. Appl Phys Lett, 2018, 112, 041110 doi: 10.1063/1.5010265
[15]
Wang M X, Xu F J, Xie N, et al. Crystal quality evolution of AlN films via high-temperature annealing under ambient N2 conditions. CrystEngComm, 2018, 20, 6613 doi: 10.1039/C8CE00967H
[16]
Tanaka S, Shojiki K, Uesugi K, et al. Quantitative evaluation of strain relaxation in annealed sputter-deposited AlN film. J Cryst Growth, 2019, 512, 16 doi: 10.1016/j.jcrysgro.2019.02.001
[17]
Xiao S Y, Suzuki R, Miyake H, et al. Improvement mechanism of sputtered AlN films by high-temperature annealing. J Cryst Growth, 2018, 502, 41 doi: 10.1016/j.jcrysgro.2018.09.002
[18]
Kumada T, Ohtsuka M, Takada K, et al. Influence of sputter power and N2 gas flow ratio on crystalline quality of AlN layers deposited at 823 K by RF reactive sputtering. Phys Status Solidi C, 2012, 9, 515 doi: 10.1002/pssc.201100489
[19]
Miyake H, Lin C H, Tokoro K, et al. Preparation of high-quality AlN on sapphire by high-temperature face-to-face annealing. J Cryst Growth, 2016, 456, 155 doi: 10.1016/j.jcrysgro.2016.08.028
[20]
Fukuyama H, Miyake H, Nishio G, et al. Impact of high-temperature annealing of AlN layer on sapphire and its thermodynamic principle. Jpn J Appl Phys, 2016, 55, 05FL02 doi: 10.7567/JJAP.55.05FL02
[21]
Washiyama S, Guan Y, Mita S, et al. Recovery kinetics in high temperature annealed AlN heteroepitaxial films. J Appl Phys, 2020, 127, 115301 doi: 10.1063/5.0002891
[22]
Kumada T, Ohtsuka M, Fukuyama H. Influence of substrate temperature on the crystalline quality of AlN layers deposited by RF reactive magnetron sputtering. AIP Adv, 2015, 5, 017136 doi: 10.1063/1.4906796
[23]
Medjani F, Sanjinés R, Allidi G, et al. Effect of substrate temperature and bias voltage on the crystallite orientation in RF magnetron sputtered AlN thin films. Thin Solid Films, 2006, 515, 260 doi: 10.1016/j.tsf.2005.12.145
[24]
Yang S B, Miyagawa R, Miyake H, et al. Raman scattering spectroscopy of residual stresses in epitaxial AlN films. Appl Phys Express, 2011, 4, 031001 doi: 10.1143/APEX.4.031001
[25]
Guo Q X, Yahata K, Tanaka T, et al. Low-temperature growth of aluminum nitride on sapphire substrates. J Cryst Growth, 2003, 257, 123 doi: 10.1016/S0022-0248(03)01565-3
[26]
Zhao L, Yang K, Ai Y J, et al. Crystal quality improvement of sputtered AlN film on sapphire substrate by high-temperature annealing. J Mater Sci: Mater Electron, 2018, 29, 13766 doi: 10.1007/s10854-018-9507-0
Fig. 1.  (Color online) The (a) (0002)- and (b) (10$ {\bar{1}} $2)-plane XRCs of the AlN films sputtered at 2000 W, 600 °C and 100 sccm N2 before and after HT annealing.

Fig. 2.  (Color online) The FWHM values of (10$ {\bar{1}} $2)-plane of the annealed AlN films with different substrate temperatures at 2000 and 3000 W.

Fig. 3.  (Color online) The (0002)-plane XRCs of the AlN films sputtered at (a) 2000 and (b) 3000 W with various substrate temperatures before HT annealing.

Fig. 4.  (Color online) Raman spectrum of the AlN films sputtered at (a) 2000 and (b) 3000 W, a N2 flux of 100 sccm, and various substrate temperatures before annealing. (c) The E2(high) peak frequency of sputtered and annealed AlN films with different substrate temperatures.

Fig. 5.  (Color online) 5 × 5 μm2 AFM images of the AlN films sputtered at 2000 W, a N2 flux of 100 sccm and substrate temperatures of (a) 550, (b) 600, (c) 650 and (d) 700 °C before annealing and (e) 550, (f) 600, (g) 650 and (h) 700 °C after annealing.

Fig. 6.  The effect of N2 flux on the FWHM values of (10$ {\bar {1}}$2)-plane of the annealed AlN films.

Fig. 7.  (Color online) The (0002)-plane XRCs of the AlN films sputtered at (a) 2000 and (b) 3000 W before annealing with various N2 fluxes.

Fig. 8.  (Color online) AFM images of the AlN films sputtered at 2000 W and 600 °C with N2 fluxes of (a) 100, (b) 150 and (c) 180 sccm before annealing and (d) 100, (e) 150 and (f) 180 sccm after annealing.

Table 1.   Sputtering parameters for the deposition of AlN films.

Sputtering parameterValue
TargetAl (> 99.9999 at%)
Substratec-sapphire
Target to substrate distance64.8 mm
Substrate temperature550–700 °C
N2 flux100–190 sccm
RF power2000 and 3000 W
Process pressure0.31 to 0.55 Pa
Deposition rate0.20–0.32 nm/s
Targeted AlN thickness200 nm
DownLoad: CSV

Table 2.   Characterizations for the sputtered AlN films.

Sputtering conditionDeposition rate (nm/s)Actual thickness (nm)FWHM values of XRC (arcsec)RMS (nm)
(0002)-plane(10$ {\bar {1}} $2)-plane
2000 W, 100 sccm, 550 °C0.210213.7736032290.852
2000 W, 100 sccm, 600 °C0.216219.7227029411.510
2000 W, 100 sccm, 650 °C0.233237.4219127142.200
2000 W, 100 sccm, 700 °C0.197200.7013024910.988
3000 W, 100 sccm, 550 °C0.330207.9318433010.850
3000 W, 100 sccm, 600 °C0.340214.1924129230.995
3000 W, 100 sccm, 650 °C0.346218.1720526641.060
3000 W, 100 sccm, 700 °C0.316199.3111925840.955
2000 W, 150 sccm, 600 °C0.206209.2837127761.860
2000 W, 180 sccm, 600 °C0.218220.4034927431.930
3000 W, 150 sccm, 600 °C0.315198.23292 2966 1.970
3000 W, 180 sccm, 600 °C0.322202.654103049 2.010
DownLoad: CSV
[1]
Li J M, Liu Z, Liu Z Q, et al. Advances and prospects in nitrides based light-emitting-diodes. J Semicond, 2016, 37, 061001 doi: 10.1088/1674-4926/37/6/061001
[2]
Wu Z H, Yan J C, Guo Y N, et al. Study of the morphology evolution of AlN grown on nano-patterned sapphire substrate. J Semicond, 2019, 40, 122803 doi: 10.1088/1674-4926/40/12/122803
[3]
Dong P, Yan J C, Zhang Y, et al. AlGaN-based deep ultraviolet light-emitting diodes grown on nano-patterned sapphire substrates with significant improvement in internal quantum efficiency. J Cryst Growth, 2014, 395, 9 doi: 10.1016/j.jcrysgro.2014.02.039
[4]
Ehrentraut D, Sitar Z. Advances in bulk crystal growth of AlN and GaN. MRS Bull, 2009, 34, 259 doi: 10.1557/mrs2009.76
[5]
Dalmau R, Moody B, Schlesser R, et al. Growth and characterization of AlN and AlGaN epitaxial films on AlN single crystal substrates. J Electrochem Soc, 2011, 158, H530 doi: 10.1149/1.3560527
[6]
Xu F J, Zhang L S, Xie N, et al. Realization of low dislocation density AlN on a small-coalescence-area nano-patterned sapphire substrate. CrystEngComm, 2019, 21, 2490 doi: 10.1039/C8CE01788C
[7]
Yan J C, Wang J X, Liu N X, et al. High quality AlGaN grown on a high temperature AIN template by MOCVD. J Semicond, 2009, 30, 103001 doi: 10.1088/1674-4926/30/10/103001
[8]
Yan J C, Wang J X, Zhang Y, et al. AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE. J Cryst Growth, 2015, 414, 254 doi: 10.1016/j.jcrysgro.2014.10.015
[9]
Chen X, Zhang Y, Yan J C, et al. Deep-ultraviolet stimulated emission from AlGaN/AlN multiple-quantum-wells on nano-patterned AlN/sapphire templates with reduced threshold power density. J Alloy Compd, 2017, 723, 192 doi: 10.1016/j.jallcom.2017.06.240
[10]
Dong P, Yan J C, Wang J X, et al. 282-nm AlGaN-based deep ultraviolet light-emitting diodes with improved performance on nano-patterned sapphire substrates. Appl Phys Lett, 2013, 102, 241113 doi: 10.1063/1.4812237
[11]
Chen X, Yan J C, Zhang Y, et al. Improved crystalline quality of AlN by epitaxial lateral overgrowth using two-phase growth method for deep-ultraviolet stimulated emission. IEEE Photonics J, 2016, 8, 1 doi: 10.1109/JPHOT.2016.2614102
[12]
Du Z J, Duan R F, Wei T B, et al. Producing deep UV-LEDs in high-yield MOVPE by improving AlN crystal quality with sputtered AlN nucleation layer. J Semicond, 2017, 38, 113003 doi: 10.1088/1674-4926/38/11/113003
[13]
Huang C, Wu P, Chang K, et al. High-quality and highly-transparent AlN template on annealed sputter-deposited AlN buffer layer for deep ultra-violet light-emitting diodes. AIP Adv, 2017, 7, 055110 doi: 10.1063/1.4983708
[14]
Susilo N, Hagedorn S, Jaeger D, et al. AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire. Appl Phys Lett, 2018, 112, 041110 doi: 10.1063/1.5010265
[15]
Wang M X, Xu F J, Xie N, et al. Crystal quality evolution of AlN films via high-temperature annealing under ambient N2 conditions. CrystEngComm, 2018, 20, 6613 doi: 10.1039/C8CE00967H
[16]
Tanaka S, Shojiki K, Uesugi K, et al. Quantitative evaluation of strain relaxation in annealed sputter-deposited AlN film. J Cryst Growth, 2019, 512, 16 doi: 10.1016/j.jcrysgro.2019.02.001
[17]
Xiao S Y, Suzuki R, Miyake H, et al. Improvement mechanism of sputtered AlN films by high-temperature annealing. J Cryst Growth, 2018, 502, 41 doi: 10.1016/j.jcrysgro.2018.09.002
[18]
Kumada T, Ohtsuka M, Takada K, et al. Influence of sputter power and N2 gas flow ratio on crystalline quality of AlN layers deposited at 823 K by RF reactive sputtering. Phys Status Solidi C, 2012, 9, 515 doi: 10.1002/pssc.201100489
[19]
Miyake H, Lin C H, Tokoro K, et al. Preparation of high-quality AlN on sapphire by high-temperature face-to-face annealing. J Cryst Growth, 2016, 456, 155 doi: 10.1016/j.jcrysgro.2016.08.028
[20]
Fukuyama H, Miyake H, Nishio G, et al. Impact of high-temperature annealing of AlN layer on sapphire and its thermodynamic principle. Jpn J Appl Phys, 2016, 55, 05FL02 doi: 10.7567/JJAP.55.05FL02
[21]
Washiyama S, Guan Y, Mita S, et al. Recovery kinetics in high temperature annealed AlN heteroepitaxial films. J Appl Phys, 2020, 127, 115301 doi: 10.1063/5.0002891
[22]
Kumada T, Ohtsuka M, Fukuyama H. Influence of substrate temperature on the crystalline quality of AlN layers deposited by RF reactive magnetron sputtering. AIP Adv, 2015, 5, 017136 doi: 10.1063/1.4906796
[23]
Medjani F, Sanjinés R, Allidi G, et al. Effect of substrate temperature and bias voltage on the crystallite orientation in RF magnetron sputtered AlN thin films. Thin Solid Films, 2006, 515, 260 doi: 10.1016/j.tsf.2005.12.145
[24]
Yang S B, Miyagawa R, Miyake H, et al. Raman scattering spectroscopy of residual stresses in epitaxial AlN films. Appl Phys Express, 2011, 4, 031001 doi: 10.1143/APEX.4.031001
[25]
Guo Q X, Yahata K, Tanaka T, et al. Low-temperature growth of aluminum nitride on sapphire substrates. J Cryst Growth, 2003, 257, 123 doi: 10.1016/S0022-0248(03)01565-3
[26]
Zhao L, Yang K, Ai Y J, et al. Crystal quality improvement of sputtered AlN film on sapphire substrate by high-temperature annealing. J Mater Sci: Mater Electron, 2018, 29, 13766 doi: 10.1007/s10854-018-9507-0
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    Received: 29 March 2020 Revised: 08 May 2020 Online: Accepted Manuscript: 03 August 2020Uncorrected proof: 10 August 2020Published: 08 December 2020

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      Wen Gu, Zhibin Liu, Yanan Guo, Xiaodong Wang, Xiaolong Jia, Xingfang Liu, Yiping Zeng, Junxi Wang, Jinmin Li, Jianchang Yan. Comprehensive study of crystalline AlN/sapphire templates after high-temperature annealing with various sputtering conditions[J]. Journal of Semiconductors, 2020, 41(12): 122802. doi: 10.1088/1674-4926/41/12/122802 W Gu, Z B Liu, Y N Guo, X D Wang, X L Jia, X F Liu, Y P Zeng, J X Wang, J M Li, J C Yan, Comprehensive study of crystalline AlN/sapphire templates after high-temperature annealing with various sputtering conditions[J]. J. Semicond., 2020, 41(12): 122802. doi: 10.1088/1674-4926/41/12/122802.Export: BibTex EndNote
      Citation:
      Wen Gu, Zhibin Liu, Yanan Guo, Xiaodong Wang, Xiaolong Jia, Xingfang Liu, Yiping Zeng, Junxi Wang, Jinmin Li, Jianchang Yan. Comprehensive study of crystalline AlN/sapphire templates after high-temperature annealing with various sputtering conditions[J]. Journal of Semiconductors, 2020, 41(12): 122802. doi: 10.1088/1674-4926/41/12/122802

      W Gu, Z B Liu, Y N Guo, X D Wang, X L Jia, X F Liu, Y P Zeng, J X Wang, J M Li, J C Yan, Comprehensive study of crystalline AlN/sapphire templates after high-temperature annealing with various sputtering conditions[J]. J. Semicond., 2020, 41(12): 122802. doi: 10.1088/1674-4926/41/12/122802.
      Export: BibTex EndNote

      Comprehensive study of crystalline AlN/sapphire templates after high-temperature annealing with various sputtering conditions

      doi: 10.1088/1674-4926/41/12/122802
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      • Corresponding author: E-mail: yanjc@semi.ac.cn and zbliu@semi.ac.cn; E-mail: yanjc@semi.ac.cn and zbliu@semi.ac.cn
      • Received Date: 2020-03-29
      • Revised Date: 2020-05-08
      • Published Date: 2020-12-10

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