Method for magnetron sputtering epitaxy of high-Sn-component single crystal GeSn material on InP substrate

Abstract

The invention provides a method for performing magnetron sputtering on an epitaxial high-Sn-component single-crystal GeSn material on an InP substrate, which comprises the following steps of: 1, selecting a single-crystal InP substrate, performing organic ultrasonic cleaning on the InP single-crystal substrate by using acetone, alcohol and deionized water, then soaking the InP single-crystal substrate in an HF (Hydrogen Fluoride) solution to remove a surface oxide layer, washing the InP single-crystal substrate by using deionized water, and after the washing is completed, drying the InP single-crystal substrate in a drying oven to obtain an epitaxial high-Sn-component single-crystal GeSn material; and the InP sheet is put on a spin coater to be spin-dried. 2, a substrate is fixed to a tray, the substrate and the tray are kept to be tightly attached, the substrate and the tray are fed into a magnetron sputtering cavity to be vacuumized to high vacuum, the tray is heated to 500 DEG C for surface deH, and high vacuum is kept in the deH process; and step 3, cooling to 205 DEG C, adopting low-power sputtering (the sputtering power ratio is that Ge / Sn is equal to 15 / 5W) to obtain a 700-nanometer single crystal GeSn epitaxial layer with the Sn component being 25%, and characterizing the single crystal GeSn epitaxial layer with the Sn component being 25% of the thin film. According to the invention, the low-temperature in-situ growth of the high-Sn-component single crystal GeSn epitaxial layer on the InP substrate under the low-power condition by adopting magnetron sputtering is proposed for the first time.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor film manufacturing, in particular to a method for magnetron sputtering epitaxial high Sn component single crystal GeSn material on an InP substrate. Background Art

[0002] Mid-wave infrared detectors have important application prospects in the fields of biomedicine, environmental monitoring, gas sensing, free space communication, etc. The IV group GeSn material has the advantages of adjustable band gap (0-0.8 eV), compatibility with CMOS process, and low cost. The absorption edge of infrared detectors based on this material can be extended to the mid- and far-infrared bands, and has extremely high application potential in the field of mid- and far-infrared detection. However, due to the low solid solubility of Sn in Ge, the large lattice mismatch between GeSn and Ge and Si, and the easy occurrence of Sn segregation during growth, it is difficult to prepare high-quality single-crystalline GeSn films with high Sn content. At present, it is difficult to epitaxially grow single-crystalline GeSn films with high Sn content on silicon substrates or Ge substrates using CVD and MBE. In recent years, there have been reports of epitaxially growing 25% single-crystalline GeSn films on InP substrates using UHV-CVD. However, due to the low temperature of 100°C, the crystal quality is poor, which is difficult to meet the needs of device preparation. Magnetron sputtering is a non-equilibrium growth method. It is widely used because of its high growth temperature, which can improve the crystal quality, and high growth rate, which can effectively inhibit Sn segregation. It also has the advantages of low cost and easy large-scale preparation. There are literature reports that magnetron sputtering is used to sputter GeSn on InP substrates and then RTA annealing is used to prepare single-crystalline GeSn films with high Sn content. However, this method has the disadvantages of easy thermal damage and poor consistency. At present, there are no reports on the use of magnetron sputtering to sputter single-crystalline GeSn films with high Sn content on InP substrates at low temperature, in situ and at low power. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for magnetron sputtering epitaxial growth of a high Sn content single crystal GeSn material on an InP substrate, by magnetron sputtering a 25% composition GeSn film on an InP substrate to achieve lattice matching growth, thereby achieving strain-free growth, reducing dislocations and improving crystal quality, and realizing the preparation of low-cost, high-quality and high Sn content single crystal GeSn films, and the spectral response achieves the effect of the mid-infrared band.

[0004] To achieve the above object, the present invention adopts the following technical solution: a method for magnetron sputtering epitaxial high Sn component single crystal GeSn material on an InP substrate, comprising the following steps.

[0005] Step 1: Select a single crystal InP substrate; Step 2: Soak the InP single crystal substrate in a solution with a volume ratio of HF:H2O=1:20 for 4 minutes; Step 3: Place the substrate on a glue spreader and spin dry the substrate at 3500 rpm for 20 seconds; Step 4: Fix the substrate on the tray, keep the substrate and the tray tightly attached, and send the tray with the fixed substrate into the high vacuum magnetron sputtering system; Step 5: Perform vacuum extraction and wait for the vacuum of the magnetron sputtering system to drop to 1×10 -4 After the temperature reached 500°C, the tray heater was heated at 15°C / min and maintained at this temperature for 2 h to remove the surface H bonds. During the H removal process, the vacuum degree of the chamber was kept higher than 1×10 -4 Pa; Step 6: After de-H is completed, the tray is cooled to 205°C, the tray speed is set to 10rpm, and 99.99% argon gas with a flow rate of 15sccm is introduced into the cavity to control the gas pressure to 0.8Pa, and the pressure is maintained for 15min; then the sputtering power of the 99.999% Ge target is set to 15W and the sputtering power of the 99.99% Sn target is set to 5W; first, the Ge target and the Sn target are pre-sputtered for 3min to ensure that the target surface is clean. After the pre-sputtering is completed, the sample baffle is opened to grow the GeSn film on the substrate surface for 120min. After the growth is completed, the heating system is turned off. After the tray is cooled to room temperature, the InP substrate GeSn film is taken out to complete the preparation of the single crystal Ge0.75Sn0.25 film, and a GeSn film lattice-matched with the InP substrate is obtained.

[0006] In a preferred embodiment, GeSn thin film is prepared by simultaneous sputtering of Ge target and Sn target by DC dual target; the purity of Sn target is 99.99%, the specification is 50.8*3mm, the purity of Ge target is 99.999%, the specification is 50.8*5mm.

[0007] In a preferred embodiment, the single crystal InP substrate has N-type crystal orientation and a resistivity of 0.6-2.5×10 -5 Ω⋅m, 355um±15μm.

[0008] Compared with the prior art, the present invention has the following beneficial effects: a method for epitaxially growing a high Sn component single crystal GeSn material on an InP single crystal substrate by magnetron sputtering, achieving lattice matching growth by magnetron sputtering a 25% component GeSn film on an InP substrate, achieving the purpose of strain-free growth, reducing dislocations, and improving crystal quality, achieving low-cost, high-quality, and high-Sn content single crystal GeSn film preparation, and achieving the effect of the spectral response in the mid-infrared band. The high Sn component single crystal GeSn film is epitaxially grown on an InP substrate by low-temperature H removal, in-situ low-temperature growth, low-power dual-target DC co-sputtering, and the selection of an InP substrate can greatly reduce the lattice mismatch between the substrate and the GeSn film, thereby improving the crystal quality of GeSn. At present, we have experimentally measured that the Sn component of the epitaxial GeSn material of the present invention has reached 25%. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A schematic diagram of sputtering a high Sn composition single crystal GeSn film on InP is schematically drawn. The GeSn film is a single crystal layered structure grown in situ on an InP substrate by sputtering.

[0010] Figure 2 A low-magnification TEM image of a sputtered high Sn-composition single-crystalline GeSn film on InP is shown, from which it can be seen that the actual thickness is about 700 nanometers.

[0011] Figure 3 The TEM high-magnification image of the sputtered high Sn content single-crystalline GeSn film on InP is drawn, and it can be seen that the GeSn film has a clear lattice and good quality. The inset is the selected area electron diffraction image of the GeSn film, from which a clear lattice can be seen, indicating that the film has a single crystal structure.

[0012] Figure 4 This is the DC-XRD pattern of the sputtered high Sn composition single crystal GeSn film on InP. It can be seen that the GeSn diffraction peak near 64° is very close to the InP substrate diffraction peak, which indicates that the GeSn film matches the InP substrate lattice.

[0013] Figure 5 This is the EDX line scan image of the sputtered high Sn composition single crystal GeSn film on InP. It can be seen that the composition of Ge and Sn elements is relatively uniform, and the Sn composition is about 25%.

[0014] Figure 6 Schematic diagram of the growth of sputtered high Sn content single crystal GeSn film on InP. Figure 6 During the sputtering process shown in a, Sn atoms and Ge atoms will be sputtered onto the surface of the heated InP substrate. During the sputtering process, a single crystal layered structure will be formed as shown in Figure b. After the growth is completed, the substrate is cooled as shown in Figure c. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0016] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0017] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0018] refer to Figure 1-6 , a method for magnetron sputtering epitaxial growth of high Sn content single crystal GeSn material on InP substrate, cutting the single crystal InP substrate into 1*1cm 2 size, substrate parameters are (N-type (100) crystal orientation, resistivity 0.6~2.5×10 -5 Ω⋅m, 355um±15μm), the InP single crystal substrate was organically cleaned using acetone, alcohol, and deionized water.

[0019] The substrate was immersed in a solution with a volume ratio of HF:H2O=1:20 for 4 minutes to remove the oxide layer on the surface of the substrate, and then rinsed with deionized water. After rinsing, the InP substrate was placed on a coating machine and rotated at 3500 rpm for 20 seconds to dry.

[0020] Fix the substrate on the tray and keep the substrate and the tray tightly attached. Put the tray with the fixed substrate into the high vacuum magnetron sputtering chamber to extract the vacuum. Wait for the vacuum in the magnetron sputtering chamber to drop to 1×10 -4 After the plate was heated to 500°C at a rate of 15°C / min, the temperature was maintained for 2 h to remove the H bonds on the substrate surface. During the H removal process, the vacuum degree of the magnetron sputtering chamber was maintained to be better than 1×10 -4 Pa.

[0021] After H removal, cool the tray to 205°C, set the tray speed to 10rpm, and introduce high-purity argon gas (99.99%) at a flow rate of 15sccm into the chamber to control the gas pressure to 0.8Pa, and maintain the pressure control for 15min. Then set the sputtering power of the high-purity Ge target (purity of 99.999%) to 15W and the sputtering power of the high-purity Sn target (purity of 99.99%) to 5W. First, pre-sputter the Ge target and Sn target for 3min to ensure that the target surface is clean. After the pre-sputtering is completed, open the sample baffle to grow the GeSn film on the substrate surface. The growth time is 120min. After the growth is completed, turn off the heating system. After the tray is cooled to room temperature, take out the InP substrate GeSn film to complete the single crystal Ge 0.75 Sn 0.25 Preparation of thin films to obtain GeSn thin films that are lattice matched to the InP substrate.

Claims

1. A method for magnetron sputtering epitaxial growth of high Sn content single crystal GeSn material on an InP substrate, characterized in that: The method comprises the following steps: Step 1: Select a single crystal InP substrate; Step 2: Soak the InP single crystal substrate in a solution with a volume ratio of HF:H2O=1:20 for 4 minutes; Step 3: Place the substrate on a glue spreader and spin dry the substrate at 3500 rpm for 20 seconds; Step 4: Fix the substrate on the tray, keep the substrate and the tray tightly fitted, and send the tray with the fixed substrate into the high vacuum magnetron sputtering system; Step 5: Perform vacuum extraction and wait for the vacuum of the magnetron sputtering system to drop to 1×10 -4 After the temperature reached 500°C, the tray heater was heated at 15°C / min and maintained at this temperature for 2 h to remove the surface H bonds. During the H removal process, the vacuum degree of the chamber was kept higher than 1×10 -4 Pa; Step 6: After de-H is completed, the tray is cooled to 205°C, the tray speed is set to 10rpm, and 99.99% argon gas with a flow rate of 15sccm is introduced into the cavity to control the gas pressure to 0.8Pa, and the pressure is maintained for 15min; then the sputtering power of the 99.999% Ge target is set to 15W and the sputtering power of the 99.99% Sn target is set to 5W; first, the Ge target and the Sn target are pre-sputtered for 3min to ensure that the target surface is clean. After the pre-sputtering is completed, the sample baffle is opened to grow the GeSn film on the substrate surface for 120min. After the growth is completed, the heating system is turned off. After the tray is cooled to room temperature, the InP substrate GeSn film is taken out to complete the preparation of the single crystal Ge0.75Sn0.25 film, and a GeSn film lattice-matched with the InP substrate is obtained.

2. The method for magnetron sputtering epitaxial growth of high Sn content single crystal GeSn material on an InP substrate according to claim 1, characterized in that: The GeSn thin film was prepared by simultaneous sputtering of Ge target and Sn target by DC dual target; the purity of Sn target was 99.99% and the specification was 50.8*3mm; the purity of Ge target was 99.999% and the specification was 50.8*5mm.

3. The method for magnetron sputtering epitaxial growth of high Sn content single crystal GeSn material on an InP substrate according to claim 1, characterized in that: The single crystal InP substrate parameters are N-type crystal orientation and resistivity of 0.6~2.5×10 -5 Ω⋅m, 355um±15μm.

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