• Journal of Semiconductors
  • Vol. 45, Issue 9, 090501 (2024)
Pengfei Qu1、2, Peng Jin1、2、*, Guangdi Zhou1、2, Zhen Wang1、2, and Zhanguo Wang1、2
Author Affiliations
  • 1Laboratory of Solid-State Optoelectronic Information Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
  • 2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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    DOI: 10.1088/1674-4926/24060003 Cite this Article
    Pengfei Qu, Peng Jin, Guangdi Zhou, Zhen Wang, Zhanguo Wang. Growth of two-inch free-standing heteroepitaxial diamond on Ir/YSZ/Si (001) substrates via laser-patterned templates[J]. Journal of Semiconductors, 2024, 45(9): 090501 Copy Citation Text show less

    Abstract

    (Color online) Schematic diagram of fabrication procedure of heteroepitaxial diamond on Ir/YSZ/Si (001). (a) 2-inch Si (001) substrate. (b) YSZ buffer layer deposition. (c) Ir buffer layer deposition. (d) Diamond nucleation by BEN. (e) Thin diamond growth. (f) Laser patterned diamond template. (g) Thick diamond growth. (h) Diamond self-detachment.

    Figure 1.(Color online) Schematic diagram of fabrication procedure of heteroepitaxial diamond on Ir/YSZ/Si (001). (a) 2-inch Si (001) substrate. (b) YSZ buffer layer deposition. (c) Ir buffer layer deposition. (d) Diamond nucleation by BEN. (e) Thin diamond growth. (f) Laser patterned diamond template. (g) Thick diamond growth. (h) Diamond self-detachment.

    (Color online) (a) X-ray diffractograms of θ−2θ scan of the heteroepitaxial diamond on Ir/YSZ/Si (001). (b) In-plane φ scan of diamond {111} and Ir {111} at a polar angle of χ = 54.74°. (c) X-ray pole figure of diamond {111} diffraction peaks. (d) XRCs of diamond (400), (e) diamond (311), and (f) diamond (220) diffraction peaks from the freestanding diamond.

    Figure 2.(Color online) (a) X-ray diffractograms of θ−2θ scan of the heteroepitaxial diamond on Ir/YSZ/Si (001). (b) In-plane φ scan of diamond {111} and Ir {111} at a polar angle of χ = 54.74°. (c) X-ray pole figure of diamond {111} diffraction peaks. (d) XRCs of diamond (400), (e) diamond (311), and (f) diamond (220) diffraction peaks from the freestanding diamond.

    (Color online) (a) Picture of the 2-inch freestanding diamond crystal grown on Ir/YSZ/Si (001). (b) Microscope image of the as-grown diamond surface after plasma etching to reveal dislocation.

    Figure 3.(Color online) (a) Picture of the 2-inch freestanding diamond crystal grown on Ir/YSZ/Si (001). (b) Microscope image of the as-grown diamond surface after plasma etching to reveal dislocation.

    Significant endeavors have been dedicated to diminishing dislocation densities and releasing stress in heteroepitaxial diamonds. In 2017, Schreck et al. fabricated an around 92 mm diameter, 1.6 mm thick freestanding heteroepitaxial diamond plate on Ir/YSZ/Si (001) (with YSZ = yttria stabilized zirconia), the largest single-crystal diamond ever reported[14]. This achievement was facilitated by applying high-power conditions (915 MHz) in their microwave-plasma chemical vapor deposition (MPCVD) setup to ensure a more homogeneous growth environment. Besides, Kim et al. grew 1-inch high-quality self-supported diamonds with a thickness ranging from 500−600 μm after double-sided polishing on Ir (001)/sapphire (112¯0) using the microneedle method[11]. Subsequently, they accomplished 2-inch high-quality freestanding monocrystalline diamonds on A-sapphire substrates with a misoriented angle of up to 7° in a step-flow growth mode[12]. This letter presents a practical and dependable approach for growing sizable diamond single crystals. We introduce the utilization of a laser beam to create patterns on the surface of a 50 nm diamond layer grown on BEN-treated Ir/YSZ/Si (001) substrates. These laser-patterned templates effectively ease the stress within the diamond layer, thereby facilitating the growth of a robust 2-inch freestanding diamond. The resultant diamond remains intact, devoid of cracks, promising crystal quality and low dislocation density.

    Fig. 1 illustrates schematically the fabrication process of the freestanding heteroepitaxial diamond grown on Ir/YSZ/Si (001) via laser-patterned templates. Firstly, a 100 nm thick YSZ epilayer and a 120 nm thick Ir epilayer were sequentially deposited on a 2-inch Si (001) single-crystal substrate using a PLD setup. Details of preparing the YSZ and Ir epilayers are described in our previous work[20, 21]. Then, BEN treatment for diamond nucleation was performed on the prepared Ir/YSZ/Si (001) substrate in a specialized apparatus (DN2106) based on microwave plasma. The bias voltage was −300 V, and the duration was 40 min. Onto the BEN-treated Ir composite substrate, a thin diamond film of around 50 nm was grown. A 355-nm ultraviolet laser with a power of 500 mW was employed to create 500 μm × 500 μm square patterns with lateral faces along <110> direction. The width treated by the laser is 20 μm. The growth of a thick diamond layer was then carried out using the MPCVD reactor under optimized growth conditions. The diamond patterns underwent an epitaxial lateral overgrowth (ELO) process to achieve a coalescence, forming a closed and continuous diamond epilayer at the first 200 μm thickness. At the latter stage of the CVD growth, nitrogen was slightly added to the ambient gas to increase the growth rate. During the cooling process, the diamond/Ir layers automatically detached from the Si substrate due to the coefficient of thermal expansion (CTE) induced thermal strain. The growth of the thick diamond lasted for 80 h, resulting in a final thickness of around 400 μm.

    In short, 2-inch free-standing diamonds were prepared by using heteroepitaxy on composite Ir/YSZ/Si (001) substrates. To release stress, patterned templates were fabricated using laser etching after the initial growth of 50-nm-diamond. Then, the subsequent growth was completed on a patterned template. The FWHM of the diamond (400) and (311) X-ray rocking curves were 313 and 359 arcsecs, respectively. The dislocation density determined by counting etching pits was approximately 2.2 × 107 cm−2. These results evidence that the laser-patterned method can effectively release stress during the growth of large-size diamonds, offering a simpler and more cost-effective alternative to the traditional photolithography-patterned scheme.

    Fig. 3(a) shows a picture of the 2-inch freestanding diamond crystal with a thickness of 400 μm. The dim color is a result of nitrogen impurities. Owing to the thermal strain and the partial attachment of the diamond to the Ir interface, the diamond/Ir layers detached from the Si substrate during the cooling process. This diamond plate was obtained without cracks and fracturing. To quantitatively evaluate dislocation density and its distribution, we subjected the diamond surface to H2/O2 plasma etching within the MPCVD setup. Under the etching conditions involving a microwave power of 3 kW, a gas pressure of 150 Torr, and a substrate temperature of 850 °C, the process was executed for 20 min. The density of these dislocation features was determined to be approximately 2.2 × 107 cm−2, a value consistent with the lowest dislocation levels observed in heteroepitaxial diamonds.

    As an ultra-wide bandgap semiconductor, diamond garners significant interest due to its exceptional physical properties[13]. These superior characteristics make diamonds highly promising for applications in power electronics[4], deep-ultraviolet detectors[5], high-energy particle detectors[6], and quantum devices based on color centers[7]. A high-quality inch-sized monocrystalline diamond wafer is fundamental for massive semiconductor device research. Nevertheless, preparing such diamond wafers constitutes one of the major technological challenges in commercializing diamond materials and devices. Over several decades of development, the heteroepitaxial growth of diamonds on Ir composite substrates, combined with bias-enhanced nucleation (BEN) process, has emerged as the most promising method for producing inch-sized monocrystalline diamonds[815]. However, achieving large-sized heteroepitaxial diamonds in practice remains challenging. The disparity in lattice parameters between hetero-substrates and diamonds leads to high threading dislocation densities, typically in the range of 107−109 cm−2 for a few hundred micrometers thickness[16]. Additionally, the complex strain control within the diamond–iridium composite system and the thermal mismatch due to differences in thermal expansion coefficients induce stress up to the GPa level in diamond thin films[17, 18]. This stress often causes cracking of the diamond epitaxial layers, hindering the growth of thick diamond wafers[19].

    Fig. 2 shows the X-ray diffraction (XRD) results of the heteroepitaxial diamond grown on Ir/YSZ/Si (001) for 80 h. The resultant diamond is around 400 μm thick. The XRD θ−2θ scan shown in Fig. 2(a) exhibits four prominent diffraction peaks corresponding to Ir (200) (2θ = 47.3°), Si (400) (2θ = 69.2°), Ir (400) (2θ = 106.7°), and diamond (400) (2θ = 119.3°), verifying a pure (001)-oriented alignment and an excellent crystallinity. Mutual orientations among the diamond, Ir, YSZ, and Si substrate were verified by an in-plane φ scan of the {111} diffraction peaks of each layer at χ = 54.74°. As shown in Fig. 2(b), the φ scan results of diamond and iridium layers show an exact quadruple symmetry with φ angles occurring at φ = 0°, 90°, 180°, and 270°. No diffraction peaks of the YSZ layer and silicon substrate (not shown here) were detected, probably because they exceeded the penetration depth of X-rays. It was proved that the Ir/YSZ/Si substrate has a cube-on-cube crystallographic epitaxial relationship in our previous work. Therefore, this result demonstrates the same crystallographic epitaxial relationship in the diamond/Ir/YSZ/Si system. Furthermore, the X-ray pole figure of diamond {111} diffractions from the as-grown diamond crystal is shown in Fig. 2(c). The absence of additional peaks except for four {111} diffraction peaks evidences that no twinning is found in the diamond crystal. The X-ray rocking curves (XRCs) of diamond (400), (311), and (220) diffractions are displayed in Figs. 2(d)−2(f), respectively. The full width at half maximum (FWHM) of respective XRCs are 313.5, 359.1, and 1228.6 arcsecs, respectively, confirming the good epitaxial quality of the resultant diamond.

    References

    [1] C J H Wort, R S Balmer. Diamond as an electronic material. Mater Today, 11, 22(2008).

    [2] J Isberg, J Hammersberg, E Johansson et al. High carrier mobility in single-crystal plasma-deposited diamond. Science, 297, 1670(2002).

    [3] A V Inyushkin, A N Taldenkov, V G Ralchenko et al. Thermal conductivity of high purity synthetic single crystal diamonds. Phys Rev B, 97, 144305(2018).

    [4] T Kwak, J Lee, U Choi et al. Diamond Schottky barrier diodes fabricated on sapphire-based freestanding heteroepitaxial diamond substrate. Diam Relat Mater, 114, 108335(2021).

    [5] M Feng, P Jin, X Meng et al. Performance of metal-semiconductor-metal structured diamond deep-ultraviolet photodetector with a large active area. J Phys D: Appl Phy, 55, 404005(2022).

    [6] M Salvadori, F Consoli, C Verona et al. Accurate spectra for high energy ions by advanced time-of-flight diamond-detector schemes in experiments with high energy and intensity lasers. Sci Rep, 11, 3071(2021).

    [7] S Prawer, A D Greentree. Diamond for quantum computing. Science, 320, 1601(2008).

    [8] M Schreck, J Asmussen, S Shikata et al. Large-area high-quality single crystal diamond. MRS Bull, 39, 504(2014).

    [9] J C Arnault, K H Lee, J Delchevalrie et al. Epitaxial diamond on Ir/SrTiO3/Si (001): From sequential material characterizations to fabrication of lateral Schottky diodes. Diam Relat Mater, 105, 107768(2020).

    [10] Y H Tang, B Golding. Stress engineering of high-quality single crystal diamond by heteroepitaxial lateral overgrowth. Appl Phys Lett, 108, 052101(2016).

    [11] S W Kim, Y Kawamata, R Takaya et al. Growth of high-quality one-inch free-standing heteroepitaxial (001) diamond on (112¯0) sapphire substrate. Appl Phys Lett, 117, 202102(2020).

    [12] S W Kim, R Takaya, S Hirano et al. Two-inch high-quality (001) diamond heteroepitaxial growth on sapphire (112¯0) misoriented substrate by step-flow mode. Appl Phys Express, 14, 115501(2021).

    [13] K Ichikawa, K Kurone, H Kodama et al. High crystalline quality heteroepitaxial diamond using grid-patterned nucleation and growth on Ir. Diam Relat Mater, 94, 92(2019).

    [14] M Schreck, S Gsell, R Brescia et al. Ion bombardment induced buried lateral growth: the key mechanism for the synthesis of single crystal diamond wafers. Sci Rep, 7, 44462(2017).

    [15] V Lebedev, J Kustermann, J Engels et al. Coalescence as a key process in wafer-scale diamond heteroepitaxy. J Appl Phys, 135, 145302(2024).

    [16] C Stehl, M Fischer, S Gsell et al. Efficiency of dislocation density reduction during heteroepitaxial growth of diamond for detector applications. Appl Phys Lett, 103, 151905(2013).

    [17] H Aida, T Ihara, R Oshima et al. Analysis of external surface and internal lattice curvatures of freestanding heteroepitaxial diamond grown on an Ir (001)/MgO (001) substrate. Diam Relat Mater, 136, 110026(2023).

    [18] M Kasu, R Takaya, S W Kim. Growth of high-quality inch-diameter heteroepitaxial diamond layers on sapphire substrates in comparison to MgO substrates. Diam Relat Mater, 126, 109086(2022).

    [19] Y Kimura, T Ihara, T Ojima et al. Physical bending of heteroepitaxial diamond grown on an Ir/MgO substrate. Diam Relat Mater, 110055(2023).

    [20] P Qu, P Jin, G Zhou et al. Epitaxial growth of high-quality yttria-stabilized zirconia films with uniform thickness on silicon by the combination of PLD and RF sputtering. Surf Coat Technol, 456, 129267(2023).

    [21] G Zhou, P Qu, X Huo et al. The deposition of Ir/YSZ double-layer thin films on silicon by PLD and magnetron sputtering: Growth kinetics and the effects of oxygen. Results Phys, 47, 106357(2023).

    Pengfei Qu, Peng Jin, Guangdi Zhou, Zhen Wang, Zhanguo Wang. Growth of two-inch free-standing heteroepitaxial diamond on Ir/YSZ/Si (001) substrates via laser-patterned templates[J]. Journal of Semiconductors, 2024, 45(9): 090501
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