Production process of boron arsenide film crystal

Abstract

The invention discloses a production process of a boron arsenide film crystal, and belongs to the technical field of compound semiconductor material synthesis. The process comprises the following steps: step 1, placing a silicon substrate in a deposition chamber, and starting a molecular pump to vacuumize the deposition chamber; 2, argon is used as carrier gas, and borane is carried into the deposition chamber; then argon is used as carrier gas, and arsine is carried into the deposition chamber; 3, heating the deposition chamber, preserving heat after heating is completed, then electrifying to continuously release a high-voltage arc, forming arsenic and boron in an ionic state under bombardment of the high-voltage arc, and growing a cubic boron arsenide thin film wafer on the silicon substrate; and 4, after the reaction is completed, cooling to room temperature, and taking out a product to obtain a finished product of the epitaxial cubic boron arsenide thin film wafer on silicon. The plasma technology is adopted, argon is used for carrying arsine and borane, the cubic boron arsenide thin film wafer grows on the silicon substrate, and the method has the advantages of being lower in reaction temperature, higher in reaction efficiency, good in safety and the like.

Description

Technical Field

[0001] The invention relates to the technical field of compound semiconductor material synthesis, and in particular to a production process of boron arsenide thin film crystals. Background Art

[0002] Cubic boron arsenide, chemical formula C-BAs, is a new type of compound semiconductor crystal material. This material has many excellent properties, such as: the band gap is 2.02eV at 300K, which is very suitable for semiconductor devices. Its thermal conductivity is as high as 1200W / (m·K), which is much higher than the 148W / (m·K) of silicon. At the same time, this semiconductor material has the characteristics of high bipolar carrier mobility, that is, the mobility of electrons and holes in cubic boron arsenide is very high, up to 1550cm 2 / V·s, which is comparable to the electron mobility of silicon (for comparison, the hole mobility of silicon is only 450cm 2 / V·s). Because cubic boron arsenide has both high carrier mobility and very high thermal conductivity, the material is known as the "strongest semiconductor material" for manufacturing semiconductor devices.

[0003] At present, the synthesis process of cubic boron arsenide is mainly through gas-solid phase reaction (arsine and boron element) or solid-solid phase reaction (arsenic element and boron element). Both methods are difficult to produce boron arsenide films with uniform thickness, and the reaction temperature is high and the reaction efficiency is low. Summary of the invention

[0004] Based on the above technical problems, the present invention proposes a production process of boron arsenide thin film crystals.

[0005] The technical solution adopted by the present invention is:

[0006] A production process of boron arsenide thin film crystals, comprising the following steps:

[0007] Step 1: Place the silicon substrate in the deposition chamber and start the molecular pump to evacuate the deposition chamber;

[0008] Step 2: Using argon as carrier gas, carry borane into the deposition chamber; then using argon as carrier gas, carry arsine into the deposition chamber;

[0009] Step 3: first heat the deposition chamber, keep it warm after the heating is completed, and then turn on the power to continuously release the high-voltage arc, so that arsenic and boron in an ionized state are formed under the bombardment of the high-voltage arc, and the two react to grow a cubic boron arsenide thin film wafer on the silicon substrate;

[0010] Step 4: After the reaction is completed, the temperature is cooled to room temperature, and the product is taken out to obtain a finished product of epitaxial cubic boron arsenide thin film wafer on silicon.

[0011] Preferably, in step one: the silicon substrate is a silicon wafer substrate with a diameter of 2-5 inches; the deposition chamber adopts a plasma-enhanced chemical vapor deposition structure, i.e., a PECVD structure.

[0012] Preferably, in step one: when the vacuum degree in the deposition chamber reaches 10 -3 Pa - 10 -2 Pa, stop evacuating.

[0013] Preferably, in step two: when the pressure in the deposition chamber reaches 0.1 - 0.15 MPa, stop introducing borane; when the pressure in the deposition chamber reaches 0.2 - 0.25 MPa, stop introducing arsine. More preferably, when the pressure in the deposition chamber reaches 0.11 MPa, stop introducing borane; when the pressure in the deposition chamber reaches 0.22 MPa, stop introducing arsine.

[0014] Preferably, in step two: control the carrier gas flow rate carrying borane or arsine to be 10 - 20 L / min. More preferably, the carrier gas flow rate is 15 L / min.

[0015] Preferably, in step three: heat the temperature in the deposition chamber to 320 - 350 °C at a rate of 5 - 30 °C / min, and control the holding time to be 20 - 30 min. More preferably, heat the temperature in the deposition chamber to 350 °C at a rate of 25 °C / min, and control the holding time to be 30 min.

[0016] Preferably, in step three: control the discharge condition to be 200 - 220 eV, and the discharge time to be 15 - 50 min.

[0017] More preferably, adjust the discharge condition of the deposition chamber to 200 - 220 eV, continuously release a high-voltage arc for 15 - 20 min, then pause for 10 - 20 min. After the pressure stabilizes and no longer changes, conduct discharge again, release a high-voltage arc with an energy of 200 - 220 eV for 15 - 20 min, and then stop.

[0018] Preferably, in step four: control the temperature in the deposition chamber to gradually decrease to room temperature at a rate of 5 - 10 °C / min, and take out the product.

[0019] Preferably, in step four: the thickness of the obtained cubic boron arsenide thin film wafer is 40 - 60 μm.

[0020] The beneficial technical effects of the present invention are as follows:

[0021] The present invention adopts plasma technology and utilizes argon gas to carry arsine and borane to grow cubic boron arsenide thin film wafers on a silicon substrate. Compared with existing gas-solid phase reaction (arsine and boron element) or solid-solid phase reaction (arsenic element and boron element) and other processes, the present invention can make the two elements of arsenic and boron mix and contact more thoroughly, with higher reaction efficiency and lower required reaction temperature; in addition, the reactants arsine and borane are carried out in the entire process in a PEVCD closed deposition chamber, which greatly reduces the risk of leakage of the reactants and greatly improves safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the process of producing the boron arsenide thin film crystal of the present invention;

[0023] Figure 2 The XRD results of the synthesized boron arsenide detected by the present invention at different temperatures;

[0024] Figure 3 This is a scanning electron microscope image of the boron arsenide thin film crystal prepared in Example 1 of the present invention;

[0025] Figure 4 This is the EDS analysis spectrum of the boron arsenide thin film crystal prepared in Example 1 of the present invention;

[0026] Figure 5 This is a picture of the finished product of the epitaxial cubic boron arsenide thin film wafer on silicon in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] The present invention proposes a process for growing a cubic boron arsenide thin film wafer on a silicon substrate by plasma vapor deposition, wherein a silicon substrate is placed in a vapor deposition chamber, and high-purity argon gas is used to carry gaseous arsine and gaseous borane respectively, and ionized arsenic and boron are formed under the bombardment of a high-voltage electric arc, and the two grow a cubic boron arsenide thin film wafer on the silicon substrate, such as Figure 1 As shown, the specific process is divided into the following steps:

[0030] Step 1: Place a 3-inch diameter silicon substrate wafer in the source area of ​​the deposition chamber, start the molecular pump to evacuate the system for 15 minutes, and wait until the vacuum reaches 10 -3 Pa, stop vacuuming.

[0031] Step 2: Use argon as carrier gas to carry high-purity borane into the PECVD deposition chamber at a rate of 15 L / min. When the system pressure shows 0.11 MPa, stop the introduction of borane.

[0032] Step 3: Using argon as the carrier gas, introduce high-purity arsine into the PECVD deposition chamber at a rate of 15 L / min. Stop introducing arsine when the system pressure shows 0.22 Mpa.

[0033] Step 4: Heating; Heat the system to 350 °C at a rate of 25 °C / min to provide reaction power for the subsequent chemical reaction.

[0034] Step 5: Discharging; After the heating process is completed, maintain this temperature for 30 minutes. Adjust the PECVD discharge power to 200 eV and continuously release a high-voltage arc for 20 minutes, so that the borane and arsine introduced into the deposition chamber are completely ionized into boron ions, arsenic ions, and hydrogen ions.

[0035] Step 6: Under the above conditions, the following reaction will occur in the system: AsH3 + BH3 = BAs + 3H2.

[0036] Step 7: After continuously discharging the high-voltage arc for 20 minutes, pause for 20 minutes. After the system pressure stabilizes at 0.29 Mpa and no longer changes, release a high-voltage arc with an energy of 200 eV for another 18 minutes, and then stop, allowing the synthesis reaction to continue in the deposition chamber for 15 minutes.

[0037] Step 8: Gradually reduce the system temperature to room temperature at a rate of 5 °C / min, take out the product, and obtain a finished silicon-based epitaxial cubic boron arsenide thin film wafer with a thickness of 50 μm.

[0038] Figure 2 This is the XRD result of the synthesized boron arsenide detected by the present invention at different temperatures; it can be seen from this that the final boron arsenide product is a pure phase, with a crystal structure of zinc blende structure and a space group of F-34M. Figure 3 This is the scanning electron microscope image of the boron arsenide thin film crystal prepared in Example 1 of the present invention. At a voltage of 5 kV and a magnification of 4000 times, it can be seen from the surface image that the grain distribution is relatively uniform. Figure 4 This is the EDS analysis spectrum of the boron arsenide thin film crystal prepared in Example 1 of the present invention. According to the EDS analysis results, the ratio of As and B is basically 1:1. Figure 5 This is a picture of the finished silicon-based epitaxial cubic boron arsenide thin film wafer in Example 1 of the present invention.

[0039] Example 2

[0040] A production process for boron arsenide thin film crystals, comprising the following steps:

[0041] Step 1: Place the silicon substrate in the deposition chamber and start the molecular pump to evacuate the deposition chamber.

[0042] The silicon substrate is a silicon wafer substrate with a diameter of 2 inches; the deposition chamber adopts a plasma-enhanced chemical vapor deposition structure, namely PEVCD. When the vacuum degree in the deposition chamber reaches 10 -2 Pa, stop evacuating.

[0043] Step 2: Use argon as the carrier gas to carry borane into the deposition chamber; then use argon as the carrier gas to carry arsine into the deposition chamber. The above-mentioned carrying is specifically to enter the deposition chamber by mixing a large amount of inert gas and a small amount of arsine gas, etc.

[0044] Control the flow rate of the carrier gas carrying borane or arsine to be 10 L / min. When the pressure in the deposition chamber reaches 0.15 MPa, stop introducing borane; when the pressure in the deposition chamber reaches 0.25 MPa, stop introducing arsine.

[0045] Step 3: First heat the deposition chamber, keep it warm after heating, and then apply electricity to continuously release a high-voltage arc. Under the bombardment of the high-voltage arc, ionic arsenic and boron are formed, and the two react to grow a cubic boron arsenide thin film wafer on the silicon substrate.

[0046] Heat the temperature in the deposition chamber to 320 °C at a rate of 10 °C / min, and control the heat preservation time to be 20 min. Adjust the discharge condition of the deposition chamber to 220 eV, apply electricity to continuously release a high-voltage arc for 15 min, then pause for 20 min. After the pressure is stable and no longer changes, discharge again, release a high-voltage arc with an energy of 220 eV for 15 min, and then stop.

[0047] Step 4: After the reaction is completed, control the temperature of the deposition chamber to gradually decrease to room temperature at a rate of 5 °C / min, take out the product, and obtain a finished cubic boron arsenide thin film wafer epitaxially grown on silicon.

[0048] Example 3

[0049] A production process of a boron arsenide thin film crystal, comprising the following steps:

[0050] Step 1: Place the silicon substrate in the deposition chamber and start the molecular pump to evacuate the deposition chamber.

[0051] The silicon substrate is a silicon wafer substrate with a diameter of 5 inches; the deposition chamber adopts a plasma-enhanced chemical vapor deposition structure, namely PEVCD. When the vacuum degree in the deposition chamber reaches 10 -3 Pa, stop evacuating.

[0052] Step 2: Use argon as the carrier gas to carry borane into the deposition chamber; then use argon as the carrier gas to carry arsine into the deposition chamber.

[0053] Control the flow rate of the carrier gas carrying borane or arsine to 20 L / min. When the pressure in the deposition chamber reaches 0.1 MPa, stop the introduction of borane; when the pressure in the deposition chamber reaches 0.2 MPa, stop the introduction of arsine.

[0054] Step 3: First, heat the deposition chamber, keep it warm after heating, and then apply electricity to continuously release a high-voltage arc. Under the bombardment of the high-voltage arc, ionic arsenic and boron are formed. The two react and grow a cubic boron arsenide thin film wafer on the silicon substrate.

[0055] Heat the temperature in the deposition chamber to 350 °C at a rate of 20 °C / min and control the heat preservation time to be 30 min. Adjust the discharge condition of the deposition chamber to 200 eV, apply electricity to continuously release a high-voltage arc for 20 min, then pause for 20 min. After the pressure stabilizes and no longer changes, discharge again and release a high-voltage arc with an energy of 200 eV for 20 min, and then stop.

[0056] Step 4: After the reaction is completed, control the temperature of the deposition chamber to gradually decrease to room temperature at a rate of 7 °C / min, take out the product, and obtain the finished product of the epitaxial cubic boron arsenide thin film wafer on silicon.

[0057] The present invention ionizes borane and arsine into plasma at high temperature and high voltage, and uses the chemical reaction activity of the plasma to promote the efficient synthesis reaction of arsenic and boron, and deposits and forms a thin film wafer on the surface of the silicon substrate. From a process perspective, this reaction process is clean and efficient, and the surface of the formed cubic boron arsenide deposition film is uniform, which has positive significance for production and use.

[0058] For the parts not described in the above manner, the existing technology can be adopted or borrowed to achieve.

[0059] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A production process of boron arsenide thin film crystal, characterized in that It includes the following steps: Step 1: Place the silicon substrate in the deposition chamber and start the molecular pump to evacuate the deposition chamber. Step 2: Use argon as the carrier gas to carry borane into the deposition chamber; then use argon as the carrier gas to carry arsine into the deposition chamber. Step 3: First heat the deposition chamber, keep it warm after heating is completed, then apply electricity to continuously release a high-voltage arc. Under the bombardment of the high-voltage arc, ionic arsenic and boron are formed, and the two react to grow a cubic boron arsenide thin film wafer on the silicon substrate. Step 4: After the reaction is completed, cool down to room temperature, take out the product to obtain a finished cubic boron arsenide thin film wafer epitaxially grown on silicon.

2. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 1: The silicon substrate is a silicon wafer substrate with a diameter of 2 - 5 inches; the deposition chamber adopts a plasma-enhanced chemical vapor deposition structure.

3. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 1: When the vacuum degree in the deposition chamber reaches 10 -3 Pa - 10 -2 Pa, stop evacuating.

4. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 2: When the pressure in the deposition chamber reaches 0.1 - 0.15 MPa, stop introducing borane; when the pressure in the deposition chamber reaches 0.2 - 0.25 MPa, stop introducing arsine.

5. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that In Step 2: Control the flow rate of the carrier gas carrying borane or arsine to be 10 - 20 L / min.

6. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 3: Heat the temperature in the deposition chamber to 320 - 350 °C at a rate of 5 - 30 °C / min and control the heat preservation time to be 20 - 30 min.

7. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 3: Control the discharge conditions to be 200 - 220 eV and the discharge time to be 15 - 50 min.

8. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 3: Adjust the discharge conditions of the deposition chamber to 200 - 220 eV, continuously release a high-voltage arc for 15 - 20 min, then pause for 10 - 20 min. After the pressure stabilizes and no longer changes, conduct discharge again, release a high-voltage arc with an energy of 200 - 220 eV for 15 - 20 min, and then stop.

9. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 4: Control the temperature of the deposition chamber to gradually decrease to room temperature at a rate of 5 - 10 °C / min and take out the product.

10. The production process of a boron arsenide thin film crystal according to claim 1, characterized in that, In Step 4: The thickness of the obtained cubic boron arsenide thin film wafer is 40 - 60 μm.

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