The diamond is known as the “ultimate semiconductor” because of its ultra-high bandgap width, high thermal conductivity, and excellent chemical and physical properties. Large-size single-crystal diamonds with low defect densities and ultra-smooth and ultra-flat surfaces have good application prospects in aerospace, semiconductor devices, and optical windows. One of the key factors to achieve industrial applications is meeting the size standards. A large number of studies have shown that the difficulty in limiting the preparation of high-quality, large-size single-crystal diamonds lies in the control of defects and the increase in the deposition rate. Restricted by the preparation mechanism, studies have shown that the mosaic splicing method is the most effective means of overcoming the size limit and realizing the preparation of large-size single-crystal diamond wafers. To address the limitations on quality and size, homogeneous epitaxial mosaic deposition was carried out with (100) oriented chemical vapor deposition (CVD) single-crystal diamonds as seed crystals using microwave plasma CVD equipment independently built by a laboratory. The effects of different splicing interface angles on the microstructure and residual stress of the splicing seam were studied by controlling the orientation and thickness of the two seed crystals used for splicing. The microstructure of the joints after deposition was observed using laser confocal microscopy and scanning electron microscopy. The structural characterization and stress analysis of the deposited joints were performed by Raman spectroscopy and fluorescence spectroscopy, respectively. The microstructure of the joints was characterized by transmission electron microscopy (TEM). The results show that the closer the edge angle of the diamond seed crystal used for deposition is to the plasma ball, the easier it is to be affected by the edge-discharge effect of the plasma and produce a relatively higher electric field, which improves the cracking ability of the gas in the reaction chamber and increases the concentration of the ionized plasma group. In addition, compared with the 90° splicing interface angle, the lap-splicing interface prepared at a certain tilt angle is covered by the seed crystal to a certain extent, which reduces the concentration of carbon-containing precursors entering the splicing seam for lateral deposition. Therefore, it is important to study the influence of the splicing interface angle on the preparation of large-size single-crystal diamonds by mosaic splicing. Mosaic splicing deposition was performed at a splicing interface angle of 60°. The prepared epitaxial layer was the most flat at the splicing joint, and the splicing deposition quality was high. The deposited epitaxial layer was relatively flat, thereby achieving the ideal splicing effect. No carbon atom shift due to mutual traction and extrusion were observed in the TEM samples. When there is compressive stress in the diamond crystal, the lattice vibration and scattering are enhanced, the spectrum is red-shifted, and the first-order Raman peak of the diamond is >1 332.5 cm-1. When there is tensile stress in the diamond crystal, the lattice vibration and scattering are weakened, the spectrum is blue-shifted, and the first-order Raman peak of the diamond is <1 332.5 cm-1. Therefore, the stress can be calculated according to the difference between the moving spectrum and standard value. Mosaic splicing deposition was performed at a 60°splicing interface angle. The residual stress at the splicing seam of the prepared epitaxial layer was the lowest at only 0.42 GPa. Compared with the 30° sample, the residual stress at the splicing seam was reduced by 10.39%. Compared with the 90° splicing sample, the residual stress at the splicing seam was reduced by 27.37%. This shows that using a certain angle to construct the splicing interface is more conducive to the preparation of large-size single-crystal diamond. This provides a research direction for the preparation of large-size single-crystal diamond substrates.
Key words
microwave plasma chemical vapor deposition (MPCVD) /
mosaic /
interface control /
homogeneous extension /
single crystal diamond
{{custom_keyword}} /
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] SIMON R B, ANAYA J, FAILI F, et al.Effect of grain size of polycrystalline diamond on its heat spreading properties[J]. Applied Physics Express, 2016, 9(6): 61302-61302.
[2] GRAEBNER J E, REISS M E, SEIBLES L, et al.Phonon scattering in chemical-vapor-deposited diamond[J]. Phys. Rev. B Condens. Matter., 1994, 50(6): 3702-3713.
[3] 吕反修. 大面积光学级金刚石自支撑膜制备、性能及其在高技术领域应用前景[J]. 中国表面工程,2010,23(3):1-9,13.
LÜ Fanxiu.Large area optical grade freestanding diamond films: deposition, characterization and high technology application prosperous[J]. China Surface Engineering, 2010, 23(3): 1-9, 13. (in Chinese)
[4] ISBERG J, HAMMERSBERG J, JOHANSSON E, et al.High carrier mobility in single-crystal plasma-deposited diamond[J]. Science, 2002, 297(5587): 1670-1672.
[5] CALVANI P, BELLUCCI A, GIROLAMI M, et al.Black diamond for solar energy conversion[J]. Carbon, 2016, 105: 401-407.
[6] NAD S, CHARRIS A, ASMUSSEN J, et al.MPACVD growth of single crystalline diamond substrates with PCD rimless and expanding surfaces[J]. Applied Physics Letters, 2016, 109(16): 162103.
[7] WANG Xiwei, DUAN Peng, CAO Zhenzhong, et al.Surface morphology of the interface junction of CVD mosaic single-crystal diamond[J]. Materials (Basel), 2019, 13(1): 91.
[8] JANSSEN G, GILING L J, et al."Mosaic" growth of diamond[J]. Diamond & Related Materials, 1995, 4(7): 1025-1031.
[9] DUFOUR F C, GICQUEL A, et al.Study for fabricating large area diamond single-crystal layers[J]. Thin Solid Films, 1997, 308: 178-185.
[10] SHU Guoyang, DAI Bing, RALCHENKO V G, et al.Epitaxial growth of mosaic diamond: Mapping of stress and defects in crystal junction with a confocal Raman spectroscopy[J]. Journal of Crystal Growth, 2017, 463: 19-26.
[11] YAN C S, VOHRA Y K, MAO H K W, et al. Very high growth rate chemical vapor deposition of single-crystal diamond[J]. Proceedings of the National Academy of Sciences of the United States of America, 2002, 99(20): 12523-12525.
[12] 胡付生,杨明阳,袁其龙,等. 金刚石表面沟槽的横向拼接生长研究[J]. 硬质合金,2020,37(2):106-112.
HU Fusheng, YANG Mingyang, YUAN Qilong, et al.Investigation of the transverse splicing growth of grooves on diamond surface[J]. Cemented Carbide, 2020, 37(2): 106-112. (in Chinese)
[13] MOKUNO Y, CHAYAHARA A, YAMADA H, et al.Synthesis of large single crystal diamond plates by high rate homoepitaxial growth using microwave plasma CVD and lift-off process[J]. Diamond & Related Materials, 2007, 17(4-5): 415-418.
[14] ACHARD J, TALLAIRE A, SUSSMANN R, et al.The control of growth parameters in the synthesis of high-quality single crystalline diamond by CVD[J]. Journal of Crystal Growth, 2005, 284(3-4): 396-405.
[15] 孙祁,汪建华,刘繁,等. 氢气流量对大面积金刚石膜沉积的影响[J]. 中国表面工程,2018,31(2):75-84.
SUN Qi, WANG Jianhua, LIU Fan, et al, Effects of hydrogen flow rate on deposition of large area diamond films[J]. China Surface Engineering, 2018, 31(2): 75-84. (in Chinese)
[16] YAMADA H, CHAYAHARA A, MOKUNO Y, et al.Simulation of microwave plasmas concentrated on the top surface of a diamond substrate with finite thickness[J]. Diamond and Related Materials. 2006, 15: 1383-1388.
[17] 方亮,王万录,陈星明,等. 用拉曼波谱分析金刚石膜的内应力[J]. 重庆大学学报(自然科学版),1999(5):79-84.
FANG Liang, WANG Wanlu, CHEN Xingming, et al, Analysis on internal stress in polycrystalline diamond films measured by raman spectroscopy[J]. Journal of Chongqing University(Natural Science Edition), 1999(5): 79-84. (in Chinese)
[18] WANG Wanlu, LIAO Kejun, GAO Jinying, et al.Internal stress analysis in diamond films formed by d.c. plasma chemical vapour deposition[J]. Thin Solid Films. 1992, 215(2): 174-178.
[19] TARDIEU A, CANSELL F, PETITET J P, et al.Pressure and temperature dependence of the first-order Raman mode of diamond[J]. Journal of Applied Physics, 1990, 68(7): 3243-3245.
[20] AGER J W, DRORY M D, Quantitative measurement of residual biaxial stress by Raman spectroscopy in diamond grown on a Ti alloy by chemical vapor deposition[J]. Physical Review B, Condensed Matter. 1993, 48(4): 2601-2607.
[21] LIANG Q, CHIN C Y, LAI J, et al.Enhanced growth of high quality single crystal diamond by microwave plasma assisted chemical vapor deposition at high gas pressures[J]. Applied Physics Letters, 2009, 94(2): 024103.
{{custom_fnGroup.title_en}}
Footnotes
{{custom_fn.content}}
Funding
Major Scientific and Technological Projects in Ningbo (2021ZDYF020196, 2021ZDYF020198).
{{custom_fund}}
PDF(592 KB)
