Large-size semiconductor film fog chemical vapor deposition device and method

Abstract

According to the large-size semiconductor film mist chemical vapor deposition device and method, the buffer shower nozzle is arranged in the reactor, and epitaxial growth of large-size and uniform-thickness gallium oxide films of various crystal forms can be achieved by designing the structure of the buffer shower nozzle.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor thin film growth, and in particular relates to a large-size semiconductor thin film mist chemical vapor deposition device and method. Background Art

[0002] The progress of science and technology and the development of society towards intelligence have promoted the renewal and development of semiconductor materials. Semiconductor materials have gone through the first generation dominated by silicon and germanium, the second generation represented by gallium arsenide, and the third generation represented by silicon carbide and gallium nitride. The development of these semiconductor materials is the cornerstone of the continuous innovation of electronic products and meets the needs of social development. However, the application scenarios of high-power electronic devices such as large aircraft, aircraft, large ships, and power transmission have put forward higher power density and greater voltage resistance requirements for the performance of electronic devices, which requires the discovery and research of new semiconductor materials that meet the requirements.

[0003] Ultra-wide bandgap semiconductor materials can theoretically meet the application requirements of high-power electronic devices due to their large bandgap width. Among them, although aluminum nitride and diamond have a large bandgap width, it is difficult to prepare large-size single crystal materials, so it is not easy to be used on a large scale in high-power electronic devices. In contrast, gallium oxide materials have excellent application prospects in the fields of power devices and deep ultraviolet optoelectronic devices due to their large bandgap width (4.9-5.5eV), high breakdown field strength (8MV / cm), large Baliga figure of merit (3400), and high stability.

[0004] Gallium oxide has five different crystal structures: α, β, γ, δ and ε. The β phase is the thermodynamically stable phase of gallium oxide. Other phases of gallium oxide can be converted into the β phase under certain temperature and humidity conditions, but its monoclinic structure makes the heteroepitaxial β gallium oxide crystal quality relatively low. The metastable α phase gallium oxide has a hexagonal structure, which is easy to heteroepitaxially obtain high-quality epitaxial films. Compared with the β phase, the α phase gallium oxide has a larger bandgap (5.3eV), making the α phase gallium oxide more suitable for high power density devices; and the α phase gallium oxide has the same lattice structure as aluminum oxide, indium oxide, iridium oxide, etc., so that it can be used in the form of alloy oxides to adjust the bandgap, which makes the α phase gallium oxide have an irreplaceable advantage in the application of deep ultraviolet optoelectronic devices.

[0005] At present, α-Ga2O3 can only be prepared by heteroepitaxial means. Commonly used methods for preparing α-Ga2O3 thin films include: metal oxide chemical vapor deposition (MOCVD), low pressure chemical vapor deposition (LPCVD), molecular beam epitaxy (MBE), halide vapor phase epitaxy (HVPE), atomic layer deposition (ALD), laser pulse deposition (PLD) and mist-chemical vapor deposition (Mist-CVD). Among them, the mist-chemical vapor deposition (Mist-CVD) method does not require high vacuum conditions, has a simple equipment structure, a fast film growth rate, and low epitaxy cost. Therefore, the equipment and process research on the preparation of gallium oxide thin films by the mist-chemical vapor deposition (Mist-CVD) method is becoming more and more perfect.

[0006] There are no relevant industry standards for mist-chemical vapor deposition (Mist-CVD) equipment, so the structure of the mist-chemical vapor deposition (Mist-CVD) equipment used by various scientific research institutions is flexible and changeable. Currently, common mist-chemical vapor deposition (Mist-CVD) equipment mainly includes two types: horizontal (slit structure) and vertical (hot wall heating tube furnace). When horizontal equipment is used to prepare large-sized (two inches and above) gallium oxide films, the thickness of the film gradually becomes thinner along the carrier gas transport direction, and the thickness of the film is extremely uneven. Similarly, when preparing large-sized (two inches and above) gallium oxide films in vertical equipment, it is difficult for the film to completely cover the entire substrate, and the thickness distribution of the film along the radial direction of the substrate is uneven, which greatly restricts the development of gallium oxide power devices. Summary of the invention

[0007] In view of this, the present invention aims to provide a large-scale semiconductor thin film mist chemical vapor deposition device and method to overcome the problem of uneven thickness of gallium oxide thin films grown by existing mist-chemical vapor deposition technology.

[0008] To achieve the above object, the technical solution of the present invention is achieved as follows: A large-size semiconductor thin film mist chemical vapor deposition device, comprising an atomization unit, a reactor, a buffer shower head and a rotating base; A buffer shower head is arranged in the reactor, and the buffer shower head comprises a delivery pipe, a conical transition section and a cylindrical section which are connected in sequence from left to right. The delivery pipe passes through one end of the reactor and is connected to an atomization unit, and the atomization unit is also provided with a carrier gas input port; a first buffer plate and a second buffer plate are arranged in sequence from left to right in the cylindrical section, and the first buffer plate and the second buffer plate divide the cylindrical section into three parts, which are a first buffer area, a second buffer area and a coating area from left to right; the first buffer plate is a conical plate structure, and the second buffer plate is a circular flat plate. The first buffer plate is provided with a number of straight holes perpendicular to the second buffer plate, and the second buffer plate is provided with a number of oblique holes; a rotating base facing the second buffer plate is provided in the coating area, a substrate is fixed on the rotating base, the substrate is surrounded by the cylindrical section of the coating area, the rotating base is driven to rotate by a first motor arranged outside the reactor, the first motor is installed on a moving unit, and the moving unit drives the first motor and the rotating base to move in a direction close to or away from the second buffer plate.

[0009] In some embodiments, the diameter of the straight hole is 2-10 mm, and the distance between each two adjacent straight holes is 2-5 mm; the diameter of the oblique hole is 2-10 mm; The diameter of the straight hole is equal to the diameter of the inclined hole; Preferably, the number of the oblique holes and the straight holes is equal and corresponds one to one; The angle between the central axis of the inclined hole and the surface normal of the second buffer plate is 30-70°.

[0010] In some embodiments, the length of the cylindrical segment is 50-300 mm, the distance from the center of the first buffer plate to the center of the second buffer plate is 10-200 mm; the angle α of the top angle of the first buffer plate is 90-175°; the distance between the second buffer plate and the substrate is 0.5-50 mm.

[0011] In some embodiments, the moving unit includes a moving seat and a driving mechanism, the driving mechanism includes a screw, a sliding rod, a second motor and a support seat; the screw and the sliding rod are arranged in parallel on the support seat, the second motor is connected to the screw in a transmission manner, the moving seat is slidably arranged on the sliding rod, and the moving seat is threadedly connected to the screw, and the first motor is installed on the moving seat.

[0012] In addition, the moving unit is not limited to the above structure, and any mechanism that can drive the moving seat to move back and forth can be applied to the present invention.

[0013] In some embodiments, the reactor includes a cylinder with openings at both ends and sealing flange plates fixed on both ends of the cylinder, the delivery pipe passes through one sealing flange plate, the rotating shaft connecting the rotating base and the first motor passes through another sealing flange plate, and an exhaust pipe is also connected to the other sealing flange plate, and the exhaust pipe is connected to the exhaust gas treatment unit; a heating layer is also provided on the side wall of the cylinder.

[0014] The sealing flange plate can be fixed by bolts or by clamps.

[0015] The exhaust gas treatment unit includes an alkaline scrubber, an acid scrubber, and an adsorption bottle which are connected in sequence. The alkaline scrubber contains an alkaline solution for removing acidic substances contained in the exhaust gas, the acid scrubber contains an acidic solution for removing alkaline substances contained in the exhaust gas, and the adsorption bottle contains activated carbon and desiccant for adsorbing other harmful substances in the exhaust gas.

[0016] In some embodiments, a groove is provided on the side of the rotating base facing the second buffer plate, and a boss for placing the substrate is provided at the center of the groove; 2-6 bolts are screwed on the side wall of the groove, and one end of the bolt extending into the groove is rotatably connected to the top plate. The substrate is placed in the groove, and the top plate is clamped and fixed by adjusting the bolt.

[0017] In addition, the structure for fixing the substrate is not limited to the above structure. A pressure plate may be provided on the rotating base, and the pressure plate is used to press on the surface of the substrate to fix the substrate. The substrate may also be fixed by negative pressure adsorption, and air holes are provided on the rotating base, and the rotating base is connected to the negative pressure system.

[0018] In some embodiments, a neutron irradiation unit is further provided inside the reactor facing the coating area.

[0019] The neutron irradiation unit is a neutron source, and the specific equipment may use a laser neutron source.

[0020] In some embodiments, electrode plates for generating an accelerating electric field are provided at both ends of the reactor. The generated accelerating electric field has a field strength ranging from 500V to 10kV / m, and the direction of the accelerating electric field is consistent with the direction of the carrier gas.

[0021] An electrode for generating a high-voltage electrostatic field is also provided at the gas outlet of the atomization unit.

[0022] Furthermore, the electric field electrode plates are arranged on the inner side of the sealing flange plates at both ends of the reactor to provide the accelerating electric field required to control the movement of the droplets.

[0023] The present invention also provides a large-size semiconductor thin film mist chemical vapor deposition method, which uses the large-size semiconductor thin film mist chemical vapor deposition device described above and comprises the following steps: S1, fixing the cleaned substrate on a rotating base, and then using a moving unit to move the substrate to a coating area facing the second buffer plate; S2, adding the prepared reaction source solution into the atomization unit; S3, using nitrogen to evacuate the residual gas in the reactor and preheat it; S4, after preheating, the atomization unit is turned on, and the reaction source solution is atomized to form uniform droplets; S5, introducing a carrier gas, the carrier gas carries the mist droplets into the reactor, and grows a gallium oxide film on the substrate; S6. After the growth of the gallium oxide film is completed, the atomization device and the carrier gas are turned off and kept warm; then the carrier gas is turned on and continuously introduced to empty the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and then the sample is taken out.

[0024] Exemplarily, the method further includes: in S5, the film is grown for 5-60 minutes, the atomization device is turned off, and the neutron irradiation unit is turned on to perform neutron irradiation on the growing film, the irradiation dose is set to 500-5000 kGy, the duration is 30-300 seconds, and the heating is maintained for 3-15 minutes after the irradiation is completed; this step is repeated 2-10 times; Alternatively, the method further comprises: after uniform droplets are formed in S4, turning on a high-voltage electrostatic field to charge the droplets, wherein the strength of the high-voltage electrostatic field is 5kV-100kV / m; and simultaneously turning on an accelerating electric field, wherein the strength of the accelerating electric field is 500V-10kV / m.

[0025] The electrostatic field is an electric field that charges the droplets. The method of charging the droplets is induction charging. The high-voltage electrostatic field is an optional accessory of the atomization unit and is placed in the reactor. The droplets are positively charged, and the direction of the accelerating electric field is consistent with the direction of the carrier gas.

[0026] Compared with the prior art, the large-scale semiconductor thin film mist chemical vapor deposition device and method described in the present invention have the following advantages: The large-scale semiconductor thin film mist chemical vapor deposition device of the present invention can realize the epitaxial growth of large-scale (two inches and above) gallium oxide thin films of various crystal forms and uniform thickness. In addition, the film defect density can be reduced after neutron irradiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic structural diagram of a large-scale semiconductor thin film mist chemical vapor deposition device according to an embodiment of the present invention; Figure 2 It is a schematic diagram of the structure of a horizontal large-scale semiconductor thin film mist chemical vapor deposition device; Figure 3 It is a schematic diagram of the structure of a vertical large-scale semiconductor thin film mist chemical vapor deposition device; Figure 4 The first structure of the deposition shower head described in the embodiment of the present invention; Figure 5 The second structure of the deposition shower head described in the embodiment of the present invention; Figure 6 A structural diagram of a rotating base according to an embodiment of the present invention; Figure 7 The film prepared in Example 1 of the present invention; Figure 8 The film prepared in Example 2 of the present invention; Fig. 9 The cross-sectional velocity distribution of the gas sprayed from a spray shower head without a buffer structure; Fig.10 The cross-sectional flow velocity distribution of the gas sprayed from the spray shower head with a buffer structure according to Example 1 of the present invention.

[0028] Description of reference numerals: 1. Atomizing unit; 2. Reactor; 21. Cylinder; 22. Sealing flange plate; 221. Exhaust pipe; 222. Exhaust treatment unit; 23. Heating layer; 3. Buffer shower head; 31. Delivery pipe; 32. Conical transition section; 33. Cylindrical section; 34. First buffer plate; 35. Second buffer plate; 4. Rotating base; 41. Groove; 42. Boss; 43. Bolt; 44. Top plate; 5. Rotating shaft; 6. First motor; 7. Moving seat; 8. Driving mechanism; 81. Screw; 82. Sliding rod; 83. Second motor; 84. Support seat; 9. Neutron irradiation unit. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] like Figure 1 As shown, a large-scale semiconductor thin film mist chemical vapor deposition device includes an atomization unit 1, a reactor 2, a buffer shower head 3 and a rotating base 4; The atomization unit 1 is used to atomize the reaction source solution to form droplets. The atomization means is not limited and can be high-pressure airless atomization, gas atomization, ultrasonic atomization, electrostatic atomization and other atomization methods.

[0034] The reactor 2 provides the required temperature, vacuum and other environmental conditions for the epitaxial growth of the thin film. The spatial position of the reactor 2 is not limited and can be horizontal, vertical or inclined at any angle, such as Figure 2 This is a schematic diagram of the structure of a horizontal large-scale semiconductor thin film mist chemical vapor deposition device. Figure 3 The schematic diagram of the structure of a vertical large-scale semiconductor thin film mist chemical vapor deposition device. The temperature environment range provided by the reactor 2 can be -196-1800°C, and the vacuum range can be 1×10 -4 Pa to multiple times atmospheric pressure.

[0035] The material of the buffer shower head 3 is a high temperature resistant material, including but not limited to quartz, graphite, stainless steel, high temperature alloy and the like.

[0036] The structure of the buffer shower head 3 is as follows Figure 4 and 5As shown, the buffer shower head 3 is arranged in the reactor 2, and the buffer shower head 3 includes a delivery pipe 31, a conical transition section 32 and a cylindrical section 33 connected in sequence from left to right, the diameter of the cylindrical section is 60-600mm, the delivery pipe 31 passes through one end of the reactor 2 and is connected to the atomization unit 1, and the atomization unit 1 is also provided with a carrier gas input port; a first buffer plate 34 and a second buffer plate 35 are arranged in sequence from left to right in the cylindrical section 33, and the first buffer plate 34 and the second buffer plate 35 divide the cylindrical section 33 into three parts, which are the first buffer area, the second buffer area and the coating area from left to right; the first buffer plate 34 is a conical plate structure, and the cone top of the conical plate structure faces the second buffer plate 35 Or it can be far away from the second buffer plate 35. The second buffer plate 35 is a circular flat plate. The first buffer plate 34 is provided with a plurality of straight holes perpendicular to the second buffer plate 35. The second buffer plate 35 is provided with a plurality of inclined holes. The array arrangement form of the straight holes and the inclined holes is not limited, and can be a close hexagonal arrangement, a rectangular array, etc.; the coating area is provided with a rotating base 4 facing the second buffer plate 35, the substrate is fixed on the rotating base 4, and the substrate is surrounded by the cylindrical section 33 of the coating area. The rotating base 4 is driven to rotate by a first motor 6 arranged outside the reactor 2. The first motor 6 is installed on a moving unit, and the moving unit drives the first motor 6 and the rotating base 4 to move towards or away from the second buffer plate 35.

[0037] The substrate rotates with the rotating base 4, and the mist drops pass through the first buffer plate 34 and the second buffer plate 35 under the action of the carrier gas to reach the coating area, and thin film growth is performed on the substrate. When the mist drops pass through the first buffer plate 34, the velocity distribution of the mist in the buffer zone will quickly tend to be uniform, and when the mist drops pass through the second buffer plate 35, the direction of the mist flow will change. The combination of the two buffer plates can make the mist flow evenly sprayed onto the substrate surface at a certain angle.

[0038] The opening size and shape of the delivery pipe 31 are not particularly limited, and the shape can be circular, elliptical, rectangular, irregular, etc., and the inner diameter of the opening can be 10-300 mm.

[0039] like Figure 2 and Figure 3 As shown, dilution gas can also be introduced into the delivery pipe 31, and the dilution gas can adjust the concentration of the mist, thereby affecting the growth rate to achieve the purpose of controlling the thickness of the film.

[0040] In some embodiments, the diameter of the straight hole is 2-10 mm, and the distance between each two adjacent straight holes is 2-5 mm; the diameter of the oblique hole is 2-10 mm; The diameter of the straight hole is equal to the diameter of the inclined hole; Preferably, the number of the inclined holes and the straight holes are equal and correspond one to one, and the one to one correspondence has little effect on the mist flow velocity.

[0041] The angle between the central axis of the inclined hole and the surface normal of the second buffer plate 35 is 30-70°.

[0042] The inclined holes are arranged so that the reaction raw material mist can reach the substrate surface at a certain angle, so that the distribution of the mist on the substrate surface will be more uniform and the film thickness will be more uniform.

[0043] In some embodiments, the length of the cylindrical section 33 is 50-300 mm, the distance from the center of the first buffer plate 34 to the center of the second buffer plate 35 is 10-200 mm; the angle α of the top angle of the first buffer plate 34 is 90-175°; the distance between the second buffer plate 35 and the substrate is 0.5-50 mm.

[0044] In some embodiments, the moving unit includes a moving seat 7 and a driving mechanism 8, the driving mechanism 8 includes a screw 81, a sliding rod 82, a second motor 83 and a support seat 84; the screw 81 and the sliding rod 82 are arranged in parallel on the support seat 84, the second motor 83 is transmission connected to the screw 81, the moving seat 7 is slidingly arranged on the sliding rod 82, and the moving seat 7 is threadedly connected to the screw 81, and the first motor 6 is installed on the moving seat 7.

[0045] In addition, the moving unit is not limited to the above structure, and any mechanism that can drive the moving seat 7 to move back and forth can be applied to the present invention.

[0046] In some embodiments, the reactor 2 includes a cylinder 21 with openings at both ends and sealing flange plates 22 fixed at both ends of the cylinder 21, the delivery pipe 31 passes through one sealing flange plate 22, and the rotating shaft 5 connecting the rotating base 4 and the first motor 6 passes through another sealing flange plate 22, and an exhaust pipe 221 is also connected to the other sealing flange plate 22, and the exhaust pipe 221 is connected to the exhaust gas treatment unit 222; a heating layer 23 is also provided on the side wall of the cylinder 21.

[0047] The sealing flange plate 22 can be fixed by bolts or by clamps.

[0048] The exhaust gas treatment unit 222 includes an alkaline scrubbing bottle, an acidic scrubbing bottle, and an adsorption bottle connected in sequence. The alkaline scrubbing bottle contains an alkaline solution for removing acidic substances contained in the exhaust gas, the acidic scrubbing bottle contains an acidic solution for removing alkaline substances contained in the exhaust gas, and the adsorption bottle contains activated carbon and desiccant for adsorbing other harmful substances in the exhaust gas.

[0049] In some embodiments, Figure 6As shown, a groove 41 is provided on the side of the rotating base 4 facing the second buffer plate 35, and a boss 42 for placing a substrate is provided at the center of the groove 41; 2-6 bolts 43 are screwed on the side wall of the groove 41, and one end of the bolt 43 extending into the groove 41 is rotatably connected to a top plate 44. The substrate is placed in the groove 41, and the top plate 44 is clamped and fixed by adjusting the bolt 43.

[0050] In addition, the structure for fixing the substrate is not limited to the above structure. A pressing plate may be provided on the rotating base 4, and the pressing plate is used to press on the surface of the substrate to fix the substrate. The substrate may also be fixed by negative pressure adsorption, and air holes are provided on the rotating base 4, and the rotating base 4 is connected to the negative pressure system.

[0051] In some embodiments, a neutron irradiation unit 9 is further provided inside the reactor 2 facing the coating area.

[0052] The neutron irradiation unit 9 is a neutron source, and a specific device may use a laser neutron source.

[0053] In some embodiments, electrode plates for generating an accelerating electric field are provided at both ends of the reactor. The generated accelerating electric field has a field strength ranging from 500V to 10kV / m, and the direction of the accelerating electric field is consistent with the direction of the carrier gas.

[0054] The electrostatic field is an electric field that charges the droplets. The method of charging the droplets is induction charging. The high-voltage electrostatic field is generated by electrodes arranged at the gas outlet of the atomization unit. The field strength of the high-voltage electrostatic field is 5kV-100kV / m.

[0055] More specifically, the electric field electrode plates are arranged on the inner side of the sealing flange plates 22 at both ends of the reactor to provide the accelerating electric field required to control the movement of the droplets.

[0056] The reaction source solution used in the present invention is a gallium-containing solution. The solvent is not limited and can be water, ethanol, etc., which can be acidic or neutral. The solute is a gallium-containing compound, which is not specifically limited and can be gallium chloride, gallium acetylacetonate, gallium bromide, gallium sulfate, gallium hydroxide, etc. The concentration of the reaction source solution (in terms of gallium) can be specifically limited to a range of 0.005-0.5 mol / L.

[0057] There is no specific limitation on the carrier gas, and a mixed gas of an inert gas and O2 can be used. Inert gas is generally nitrogen, which is relatively easy to obtain. Adjusting the oxygen content in the mixed gas can change the ratio of chemical reaction products and adjust the reaction rate. The addition of oxygen can improve the quality of thin film crystals to a certain extent. The reaction rate adjustment here is reflected in the fact that when the inert gas flow rate remains unchanged, the overall flow rate of the carrier gas increases after the addition of oxygen, the concentration of fog decreases, and the film growth rate decreases.

[0058] The waste gas contains some unreacted reactants and products after the reaction. Different reactants will cause the waste gas to contain alkaline or acidic substances. Most of the pollutants can be removed by passing through two acid and alkali washing bottles, and then the waste gas can be purified by passing through the adsorption bottle. The exhaust end of the waste gas treatment device is connected to a negative pressure fan to prevent the exhaust gas from being sucked back into the reaction chamber.

[0059] Example 1 Epitaxial growth of a two-inch α-Ga2O3 thin film on a sapphire substrate The film is made of Figure 3 The vertical large-scale semiconductor thin film mist chemical vapor deposition device shown in the figure is prepared. Based on the above structure, in this embodiment, the structure of the buffer shower head 3 is as follows Figure 4 The diameter of the cylindrical section is 200 mm, the length is 300 mm, the diameter of the straight hole is 8 mm, the distance between each two adjacent straight holes is 4 mm, the diameter of the inclined hole is 8 mm, the straight holes correspond to the inclined holes one by one, and the angle between the central axis of the inclined hole and the surface normal of the second buffer plate is 45°, so that the raw material mist is emitted to the substrate surface at 45°; the distance from the center of the first buffer plate to the center of the second buffer plate is 100 mm; the angle α of the top angle of the first buffer plate is 100°.

[0060] The film preparation method is as follows: 1. Substrate cleaning Place the sapphire substrate in an ultrasonic cleaning machine containing cleaning solution and perform ultrasonic cleaning for 1 minute.

[0061] Take out the substrate and use nitrogen to blow dry the cleaning liquid remaining on the surface of the substrate.

[0062] 2. Select a suitable quartz rotating base according to the substrate size, fix the sapphire substrate horizontally on the rotating base, then send the rotating base into the reactor through the moving unit, and seal the reactor through the sealing flange plate.

[0063] 3. Adjust the rotating base so that the substrate is located 2 mm above the second buffer plate and the substrate is parallel to the second buffer plate.

[0064] 4. Preparation of reaction source solution: dissolve 18.5 g of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution of about 0.025 mol / L, and add the prepared reaction source solution to the atomization unit; 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 650°C.

[0065] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit. The ultrasonic atomization frequency is 3 MHz.

[0066] 7. Introduce carrier gas. Nitrogen is used as the carrier gas with a flow rate of 400 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide film. The growth time is set to 30 minutes.

[0067] 8. After the growth of the gallium oxide film is completed, turn off the atomization device and the carrier gas and keep warm for 3 minutes. Then turn on the carrier gas and continue to introduce nitrogen to empty the residual reactants and by-products in the reaction chamber and slowly cool it to room temperature, and take out the sample.

[0068] Figure 7 The two-inch film sample prepared in this embodiment has a thickness of 1020nm at the tested position. 20 points of the prepared film were randomly selected to measure their thickness, and the average thickness was 1018nm, with a thickness standard deviation of only 26nm, indicating that the device described in the present invention can be used to prepare a gallium oxide film with relatively uniform thickness.

[0069] Example 2 Epitaxial growth of a four-inch α-Ga2O3 thin film on a sapphire substrate The film was prepared by using the same vertical large-scale semiconductor film mist chemical vapor deposition device as in Example 1.

[0070] The film preparation method is as follows: 1. Substrate cleaning Place the sapphire substrate in an ultrasonic cleaning machine containing cleaning solution and perform ultrasonic cleaning for 1 minute.

[0071] Take out the substrate and use nitrogen to blow dry the cleaning liquid remaining on the surface of the substrate.

[0072] 2. Select a suitable quartz rotating base according to the substrate size, fix the sapphire substrate horizontally on the rotating base, then send the rotating base into the reactor through the moving unit, and seal the reactor through the sealing flange plate.

[0073] 3. Adjust the rotating base so that the substrate is located 2 mm above the second buffer plate and the substrate is parallel to the second buffer plate.

[0074] 4. Preparation of reaction source solution: dissolve 18.5 g of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution of about 0.025 mol / L, and add the prepared reaction source solution to the atomization unit; 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 650°C.

[0075] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit. The ultrasonic atomization frequency is 3 MHz.

[0076] 7. Introduce carrier gas. Nitrogen is used as the carrier gas with a flow rate of 800 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide film. The growth time is set to 30 minutes.

[0077] 8. After the growth of the gallium oxide film is completed, turn off the atomization device and the carrier gas and keep warm for 3 minutes. Then turn on the carrier gas and continue to introduce nitrogen to empty the residual reactants and by-products in the reaction chamber and slowly cool it to room temperature, and take out the sample.

[0078] Figure 8 The four-inch film sample prepared in this embodiment has a thickness of 740nm at the tested position in the figure. The thickness of the prepared film was measured at 20 points randomly selected, and the average thickness was 742nm, with a thickness standard deviation of only 43nm, indicating that the device described in the present invention can be used to prepare a gallium oxide film with relatively uniform thickness.

[0079] Example 3 Epitaxial growth of a two-inch ε-Ga2O3 thin film on a sapphire substrate The film is prepared using the same vertical large-scale semiconductor thin film mist chemical vapor deposition device as in Example 1, but the inclination angle of the inclined hole is different. The angle between the central axis of the inclined hole and the surface normal of the second buffer plate is 65°, so that the raw material mist is emitted toward the substrate surface at 65°.

[0080] The film preparation method is as follows: 1. Substrate cleaning Place the sapphire substrate in an ultrasonic cleaning machine containing cleaning solution and perform ultrasonic cleaning for 1 minute.

[0081] Take out the substrate and use nitrogen to blow dry the cleaning liquid remaining on the surface of the substrate.

[0082] 2. Select a suitable quartz rotating base according to the substrate size, fix the sapphire substrate horizontally on the rotating base, then send the rotating base into the reactor through the moving unit, and seal the reactor through the sealing flange plate.

[0083] 3. Adjust the rotating base so that the substrate is located 10 mm above the second buffer plate and the substrate is parallel to the second buffer plate.

[0084] 4. Preparation of reaction source solution: dissolve 18.5 g of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution of about 0.025 mol / L, and add the prepared reaction source solution to the atomization unit; 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 850°C.

[0085] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit. The ultrasonic atomization frequency is 3 MHz.

[0086] 7. Introduce carrier gas. Nitrogen is used as the carrier gas with a flow rate of 600 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide film. The growth time is set to 30 minutes.

[0087] 8. After the growth of the gallium oxide film is completed, turn off the atomization device and the carrier gas and keep warm for 3 minutes. Then turn on the carrier gas and continue to introduce nitrogen to empty the residual reactants and by-products in the reaction chamber and slowly cool it to room temperature, and take out the sample.

[0088] Through measurement, this embodiment also produces a gallium oxide film with relatively uniform thickness.

[0089] Example 4 Epitaxial growth of a two-inch β-Ga2O3 thin film on a β-Ga2O3 substrate The film was prepared by using the same vertical large-scale semiconductor film mist chemical vapor deposition device as in Example 1.

[0090] The film preparation method is as follows: 1. Substrate cleaning The β-Ga2O3 substrate was placed in an ultrasonic cleaning machine containing cleaning solution and ultrasonically cleaned for 1 min.

[0091] Take out the substrate and use nitrogen to blow dry the cleaning liquid remaining on the surface of the substrate.

[0092] 2. Select a suitable quartz rotating base according to the substrate size, fix the sapphire substrate horizontally on the rotating base, then send the rotating base into the reactor through the moving unit, and seal the reactor through the sealing flange plate.

[0093] 3. Adjust the rotating base so that the substrate is located 2 mm above the second buffer plate and the substrate is parallel to the second buffer plate.

[0094] 4. Preparation of reaction source solution: dissolve 18.5 g of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution of about 0.025 mol / L, and add the prepared reaction source solution to the atomization unit; 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 950°C.

[0095] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit. The ultrasonic atomization frequency is 3 MHz.

[0096] 7. Introduce carrier gas. Nitrogen is used as the carrier gas with a flow rate of 2000 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide film. The growth time is set to 30 minutes.

[0097] 8. After the growth of the gallium oxide film is completed, turn off the atomization device and the carrier gas and keep warm for 3 minutes. Then turn on the carrier gas and continue to introduce nitrogen to empty the residual reactants and by-products in the reaction chamber and slowly cool it to room temperature, and take out the sample.

[0098] Through measurement, this embodiment also produces a gallium oxide film with relatively uniform thickness.

[0099] Example 5 Neutron Radiation Induced Epitaxial Growth of a Two-Inch α-Ga2O3 Thin Film on a Sapphire Substrate The film is prepared by using the same vertical large-scale semiconductor thin film mist chemical vapor deposition device as in Example 1, and on the basis of the device in Example 1, a neutron irradiation unit is also provided inside the reactor of the device facing the coating area, and the neutron irradiation unit is a neutron source, and the specific equipment can use a laser neutron source.

[0100] The film preparation method is as follows: 1. Substrate cleaning Place the sapphire substrate in an ultrasonic cleaning machine containing cleaning solution and perform ultrasonic cleaning for 1 minute.

[0101] Take out the substrate and use nitrogen to blow dry the cleaning liquid remaining on the surface of the substrate.

[0102] 2. Select a suitable quartz rotating base according to the substrate size, fix the sapphire substrate horizontally on the rotating base, then send the rotating base into the reactor through the moving unit, and seal the reactor through the sealing flange plate.

[0103] 3. Adjust the rotating base so that the substrate is located 2 mm above the second buffer plate and the substrate is parallel to the second buffer plate.

[0104] 4. Preparation of reaction source solution: dissolve 18.5 g of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution of about 0.025 mol / L, and add the prepared reaction source solution to the atomization unit; 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 650°C.

[0105] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit. The ultrasonic atomization frequency is 3 MHz.

[0106] 7. Introduce carrier gas. Nitrogen is used as the carrier gas with a flow rate of 400 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide film. The growth time is set to 10 minutes.

[0107] 8. Then, the atomization unit is turned off, and the neutron irradiation unit is turned on to neutron irradiate the growing film. The irradiation dose is set to 100 kGy, the duration is 2 min, and the heating is maintained for 10 min after the irradiation is completed.

[0108] 9. Repeat steps 7 and 8 5 times.

[0109] 10. After the growth of the gallium oxide film is completed, turn off the atomizer and the carrier gas and keep warm for 3 minutes. Then turn on the carrier gas and continue to introduce nitrogen to empty the residual reactants and by-products in the reaction chamber and slowly cool it to room temperature, and take out the sample.

[0110] Compared with Example 1, the defect density of the film prepared in this example is reduced, and the uniformity of the film thickness does not change much.

[0111] Example 6 Epitaxial growth of a two-inch α-Ga2O3 thin film on a sapphire substrate in an additional electric field environment The film is prepared by using the same vertical large-scale semiconductor thin film mist chemical vapor deposition device as in Example 1, and on the basis of the device in Example 1, electrode plates for generating an accelerating electric field are provided at both ends of the reactor of the device, and the direction of the accelerating electric field is consistent with the direction of the carrier gas, and an electrode for generating a high-voltage electrostatic field is also provided at the gas outlet of the atomization unit.

[0112] The film preparation method is as follows: 1. Substrate cleaning Place the sapphire substrate in an ultrasonic cleaning machine containing cleaning solution and perform ultrasonic cleaning for 1 minute.

[0113] Take out the substrate and use nitrogen to blow dry the cleaning liquid remaining on the surface of the substrate.

[0114] 2. Select a suitable quartz rotating base according to the substrate size, fix the sapphire substrate horizontally on the rotating base, then send the rotating base into the reactor through the moving unit, and seal the reactor through the sealing flange plate.

[0115] 3. Adjust the rotating base so that the substrate is located 2 mm above the second buffer plate and the substrate is parallel to the second buffer plate.

[0116] 4. Preparation of reaction source solution: dissolve 18.5 g of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution of about 0.025 mol / L, and add the prepared reaction source solution to the atomization unit; 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 650°C.

[0117] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit. The ultrasonic atomization frequency is 3 MHz.

[0118] 7. Turn on the high-voltage electrostatic field to charge the droplets. The field strength of the high-voltage electrostatic field is 10kV / m.

[0119] At the same time, the accelerating electric field is turned on, and the field strength of the accelerating electric field is 1 kV / m.

[0120] 8. Introduce carrier gas. Nitrogen is used as the carrier gas with a flow rate of 200 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide film. The growth time is set to 30 minutes.

[0121] 9. After the growth of the gallium oxide film is completed, turn off the atomizer and the carrier gas and keep warm for 3 minutes. Then turn on the carrier gas and continue to introduce nitrogen to empty the residual reactants and by-products in the reaction chamber and slowly cool it to room temperature, and take out the sample.

[0122] Compared with Example 1, the growth rate of the film prepared in this example is improved, the film thickness is increased, and the thickness uniformity does not change much.

[0123] Therefore, by using the device proposed in the present invention, the growth of gallium oxide films of different thicknesses can be achieved by changing the growth time, the growth of gallium oxide films of different crystal forms can be achieved by changing the growth temperature of the reaction chamber, and homoepitaxial and heteroepitaxial gallium oxide films can be achieved by using different substrates.

[0124] Comparative Example 1 Inclined hole angle Compared with Example 1, the difference is that the angle between the central axis of the inclined hole and the surface normal of the second buffer plate is 5°, so that the raw material mist is emitted toward the substrate surface at 5°.

[0125] The uniformity of the obtained film is worse than that of the embodiment, and the film has periodic thickness fluctuations, which indicates that the angle cannot be too small.

[0126] Comparative Example 2 Inclined hole angle Compared with Example 1, the difference is that the angle between the central axis of the inclined hole and the surface normal of the second buffer plate is 80°, so that the raw material mist is emitted toward the substrate surface at 80°.

[0127] The uniformity of the film thickness obtained is slightly worse than that of the embodiment, and the average thickness is thinner than that of the embodiment, indicating that too large an angle is not conducive to film growth.

[0128] Comparative Example 3 Hole spacing Compared with Example 1, the difference is that the distance between every two adjacent straight holes is 15 mm.

[0129] The thickness uniformity of the obtained film becomes worse, and the larger the pore spacing actually leads to a decrease in the pore density, making the film thickness uneven.

[0130] Comparative Example 4 Hole Diameter Compared with Example 1, the difference is that the diameter of the straight hole is 20 mm, and the diameter of the inclined hole is 20 mm.

[0131] The thickness uniformity of the obtained film deteriorates, and the pore diameter is too large, resulting in poor buffering effect and uneven film thickness.

[0132] Comparative Example 5 Setting of buffer plate Compared with the embodiment 1, the difference is that there is only the second buffer plate.

[0133] The film uniformity deteriorates and the film edge becomes thinner, which is caused by the uneven distribution of the mist flow velocity due to the lack of the first buffer plate.

[0134] Comparative Example 6 No buffer plate Compared with Example 1, the difference is that the first buffer plate and the second buffer plate are not provided (this comparative example can also be regarded as an extreme case of the large hole in Comparative Example 4, that is, the hole diameter is equal to the cylindrical section diameter, that is, there are no two buffer plates).

[0135] The thickness uniformity of the obtained thin film deteriorates.

[0136] Fig. 9 The cross-sectional flow velocity distribution of the gas sprayed from the spray shower head without buffer structure in this comparative example; Fig.10 The figure shows the cross-sectional flow velocity distribution of the gas sprayed from the spray shower head with a buffer structure in Example 1. It can be seen from the figure that the mist flow velocity with the buffer structure is more uniform, so that a film with a more uniform thickness can be obtained.

[0137] In summary, the large-scale semiconductor thin film mist chemical vapor deposition device proposed in the present invention is equipped with a buffer shower head in the reactor. By designing the structure of the buffer shower head, the epitaxial growth of large-scale and uniformly thick gallium oxide thin films of various crystal types can be achieved.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A large-scale semiconductor thin film mist chemical vapor deposition device, characterized in that: It includes an atomizing unit, a reactor, a buffer shower head and a rotating base; A buffer shower head is arranged in the reactor, and the buffer shower head comprises a delivery pipe, a conical transition section and a cylindrical section which are connected in sequence from left to right. The delivery pipe passes through one end of the reactor and is connected to an atomization unit, and the atomization unit is also provided with a carrier gas input port; a first buffer plate and a second buffer plate are arranged in sequence from left to right in the cylindrical section, and the first buffer plate and the second buffer plate divide the cylindrical section into three parts, which are a first buffer area, a second buffer area and a coating area from left to right; the first buffer plate is a conical plate structure, and a plurality of straight holes perpendicular to the second buffer plate are arranged on the first buffer plate, and a plurality of inclined holes are arranged on the second buffer plate; a rotating base facing the second buffer plate is arranged in the coating area, and a substrate is fixed on the rotating base, and the substrate is surrounded by the cylindrical section of the coating area, and the rotating base is driven to rotate by a first motor arranged outside the reactor, and the first motor is installed on a moving unit, and the moving unit drives the first motor and the rotating base to move toward or away from the second buffer plate.

2. The large-scale semiconductor thin film mist chemical vapor deposition device according to claim 1, characterized in that: The diameter of the straight hole is 2-10mm, and the distance between two adjacent straight holes is 2-5mm; the diameter of the inclined hole is 2-10mm; The diameter of the straight hole is equal to the diameter of the inclined hole; The number of inclined holes and straight holes is equal and corresponds one to one; The angle between the central axis of the inclined hole and the surface normal of the second buffer plate is 30-70°.

3. The large-scale semiconductor thin film mist chemical vapor deposition device according to claim 1, characterized in that: The length of the cylindrical section is 50-300 mm, the distance from the center of the first buffer plate to the center of the second buffer plate is 10-200 mm; the angle α of the vertex angle of the first buffer plate is 90-175°; the distance between the second buffer plate and the substrate is 0.5-50 mm.

4. The large-scale semiconductor thin film mist chemical vapor deposition device according to claim 1, characterized in that: The moving unit includes a moving seat and a driving mechanism, and the driving mechanism includes a screw, a sliding rod, a second motor and a supporting seat; the screw and the sliding rod are arranged in parallel on the supporting seat, the second motor is connected to the screw in a driving manner, the moving seat is slidably arranged on the sliding rod, and the moving seat is threadedly connected to the screw, and the first motor is installed on the moving seat.

5. The large-scale semiconductor thin film mist chemical vapor deposition device according to claim 1, characterized in that: The reactor includes a cylinder with openings at both ends and sealing flange plates fixed on both ends of the cylinder. The delivery pipe passes through one sealing flange plate, and the rotating shaft connecting the rotating base and the first motor passes through another sealing flange plate. An exhaust pipe is also connected to the other sealing flange plate, and the exhaust pipe is connected to the exhaust gas treatment unit; a heating layer is also provided on the side wall of the cylinder.

6. The large-scale semiconductor thin film mist chemical vapor deposition device according to claim 1, characterized in that: A groove is provided on the side of the rotating base facing the second buffer plate, and a boss for placing the substrate is provided at the center of the groove; 2-6 bolts are screwed on the side wall of the groove, and one end of the bolt extending into the groove is rotatably connected to the top plate.

7. The large-scale semiconductor thin film mist chemical vapor deposition device according to claim 1, characterized in that: A neutron irradiation unit is also provided inside the reactor opposite to the coating area.

8. The large-scale semiconductor thin film mist chemical vapor deposition device according to claim 1, characterized in that: Electrode plates for generating an accelerating electric field are provided at both ends of the reactor. The generated accelerating electric field has a field strength range of 500V-10kV / m, and the direction of the accelerating electric field is consistent with the direction of the carrier gas. Electrodes for generating a high-voltage electrostatic field are also provided at the gas outlet of the atomization unit.

9. A method for mist chemical vapor deposition of large-scale semiconductor thin films, characterized in that: The method uses the large-size semiconductor thin film mist chemical vapor deposition device according to any one of claims 1 to 8, comprising the following steps: S1, fixing the cleaned substrate on a rotating base, and then using a moving unit to move the substrate to a coating area facing the second buffer plate; S2, adding the prepared reaction source solution into the atomization unit; S3, using nitrogen to evacuate the residual gas in the reactor and preheat it; S4, after preheating, the atomization unit is turned on, and the reaction source solution is atomized to form uniform droplets; S5, introducing a carrier gas, the carrier gas carries the mist droplets into the reactor, and grows a gallium oxide film on the substrate; S6. After the growth of the gallium oxide film is completed, the atomization device and the carrier gas are turned off and kept warm; then the carrier gas is turned on and continuously introduced to empty the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and then the sample is taken out.

10. The method for mist chemical vapor deposition of a large-scale semiconductor thin film according to claim 9, characterized in that: The method further comprises: in S5, the film is grown for 5-60 minutes, the atomization device is turned off, and the neutron irradiation unit is turned on to neutron irradiate the grown film, the irradiation dose is set to 500-5000 kGy, the duration is 30-300 seconds, and heating is maintained for 3-15 minutes after the irradiation is completed; this step is repeated 2-10 times; Alternatively, the method further comprises: after uniform droplets are formed in S4, turning on a high-voltage electrostatic field to charge the droplets, wherein the strength of the high-voltage electrostatic field is 5kV-100kV / m; and simultaneously turning on an accelerating electric field, wherein the strength of the accelerating electric field is 500V-10kV / m.

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