A large-size semiconductor thin film mist chemical vapor deposition device and method

Abstract

The present invention provides a large-size semiconductor thin film mist chemical vapor deposition device and method. A buffer showerhead is arranged in the reactor. By designing the structure of the buffer showerhead, epitaxial growth of large-size gallium oxide thin films with uniform thickness and various crystal forms can be achieved.

Description

Technical Field

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

[0002] The progress of technology and the development of society towards intelligence have promoted the replacement and development of semiconductor materials. Semiconductor materials have gone through the first generation mainly based on 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 for the continuous innovation of electronic products and meets the needs of social development. However, for the application scenarios of high-power electronic devices such as large aircraft, aircraft, large ships, and power transmission, higher requirements for power density and greater breakdown voltage are put forward for the performance of electronic devices, which requires the discovery and research of new semiconductor materials that meet the requirements.

[0003] Due to its large bandgap, ultra-wide bandgap semiconductor materials can theoretically meet the application requirements of high-power electronic devices. Among them, although aluminum nitride, diamond, etc. have a large bandgap, it is difficult to prepare large-size single crystal materials, so it is not easy to be widely applied to high-power electronic devices on a large scale. 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 (4.9 - 5.5 eV), high breakdown field strength (8 MV / cm), large Baliga figure of merit (3400), and high stability.

[0004] Gallium oxide has five different crystal structures: α, β, γ, δ, and ε. Among them, the β-phase is the thermodynamically stable phase of gallium oxide, and other phases of gallium oxide can be transformed into the β-phase under certain temperature and humidity conditions. However, its monoclinic structure results in a relatively low crystal quality of heteroepitaxial β-gallium oxide. The metastable α-phase gallium oxide has a hexagonal structure, which is easy to perform heteroepitaxy to obtain high-quality epitaxial thin films. And compared with the β-phase, the α-phase gallium oxide has a larger bandgap (5.3 eV), making the α-phase gallium oxide more suitable for high-power density devices. Moreover, the α-phase gallium oxide has the same lattice structure as aluminum oxide, indium oxide, iridium oxide, etc., enabling the bandgap to be regulated in the form of alloy oxides, which gives the α-phase gallium oxide an irreplaceable advantage in the application of deep ultraviolet optoelectronic devices.

[0005] Currently, α-Ga2O3 can only be prepared by heteroepitaxial means. The commonly used methods for preparing α-Ga2O3 thin films include: metal-organic chemical vapor deposition (MOCVD), low-pressure chemical vapor deposition (LPCVD), molecular beam epitaxy (MBE), halide vapor phase epitaxy (HVPE), atomic layer deposition (ALD), pulsed laser 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 thin-film growth rate, and a low epitaxial cost. Therefore, the research on the equipment and process for preparing gallium oxide thin films by the mist-chemical vapor deposition (Mist-CVD) method has been increasingly improved.

[0006] There is no relevant industry standard for the mist-chemical vapor deposition (Mist-CVD) equipment. Therefore, the structures of the mist-chemical vapor deposition (Mist-CVD) equipment used by each scientific research unit are flexible and variable. Currently, the common mist-chemical vapor deposition (Mist-CVD) equipment mainly includes two types: horizontal (slit structure) and vertical (hot-wall heated tube furnace). When preparing large-size (two inches and above) gallium oxide thin films with horizontal equipment, the thickness of the thin film gradually becomes thinner along the direction of carrier gas transport, and the thickness of the thin film is extremely uneven. Similarly, when preparing large-size (two inches and above) gallium oxide thin films in vertical equipment, it is difficult for the thin film to completely cover the entire substrate, and at the same time, the thickness distribution of the thin 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 propose a large-size semiconductor thin film mist chemical vapor deposition device and method to overcome the problem of uneven growth thickness of gallium oxide thin films in the existing mist-chemical vapor deposition technology.

[0008] To achieve the above object, the technical solution of the present invention is realized as follows:

[0009] A large-size semiconductor thin film mist chemical vapor deposition device includes an atomization unit, a reactor, a buffer shower head, and a rotating base;

[0010] The buffer shower head is arranged inside the reactor. The buffer shower head includes a delivery pipe, a conical transition section, and a cylindrical section that are connected in sequence from left to right. The delivery pipe passes through one end of the reactor and is connected to the atomization unit, and the atomization unit is also provided with a carrier gas input port. Inside the cylindrical section, a first buffer plate and a second buffer plate are arranged in sequence from left to right. The first buffer plate and the second buffer plate divide the cylindrical section 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 is a conical plate structure, the second buffer plate is a circular flat plate, there are a number of straight holes perpendicular to the second buffer plate on the first buffer plate, and there are a number of inclined holes on the second buffer plate. A rotating base facing the second buffer plate is provided in the coating area, the substrate is fixed on the rotating base, 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. The first motor is installed on the 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.

[0011] In some embodiments, the diameter of the straight holes is 2 - 10 mm, and the distance between every two adjacent straight holes is 2 - 5 mm; the diameter of the inclined holes is 2 - 10 mm.

[0012] The diameter of the straight holes is equal to the diameter of the inclined holes.

[0013] Preferably, the number of the inclined holes is equal to the number of the straight holes and they are in one-to-one correspondence.

[0014] The included angle between the central axis of the inclined holes and the surface normal of the second buffer plate is 30 - 70°.

[0015] In some embodiments, 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 included angle α of the apex angle of the first buffer plate is 90 - 175°; the distance between the second buffer plate and the substrate is 0.5 - 50 mm.

[0016] In some embodiments, the moving unit includes a moving seat and a driving mechanism. The driving mechanism includes a screw rod, a sliding rod, a second motor, and a support seat; the screw rod and the sliding rod are arranged in parallel on the support seat, the second motor is in transmission connection with the screw rod, the moving seat is slidably arranged on the sliding rod, and the moving seat is in threaded connection with the screw rod. The first motor is installed on the moving seat.

[0017] In addition, the moving unit is not limited to the above structure, and any mechanism that can drive the moving seat to reciprocate can be applicable to the present invention.

[0018] In some embodiments, the reactor includes a cylindrical body with openings at both ends and sealing flange plates fixed at both ends of the cylindrical body. A delivery pipe passes through one sealing flange plate, and the rotating base and the rotating shaft of the first motor pass through the other sealing flange plate. An exhaust pipe is also connected to the other sealing flange plate and is connected to the tail gas treatment unit; a heating layer is further provided on the side wall of the cylindrical body.

[0019] The sealing flange plates can be fixed by bolts or by clamps.

[0020] The tail gas treatment unit includes an alkaline scrubber bottle, an acidic scrubber bottle, and an adsorption bottle connected in sequence. The alkaline scrubber bottle contains an alkaline solution for removing acidic substances contained in the waste gas, the acidic scrubber bottle contains an acidic solution for removing alkaline substances contained in the waste gas, and the adsorption bottle contains activated carbon and a desiccant for adsorbing other harmful substances in the waste gas.

[0021] 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 the end of each bolt extending into the groove is rotatably connected to a top plate. The substrate is placed in the groove and fixed by adjusting the bolts so that the top plate clamps the substrate.

[0022] In addition, the structure for fixing the substrate is not limited to the above structure. It can also be a pressing piece provided on the rotating base, and the pressing piece is used to press on the surface of the substrate to fix the substrate; the substrate can also be fixed by a negative pressure adsorption method. There are air holes provided on the rotating base, and the rotating base is connected to a negative pressure system.

[0023] In some embodiments, a neutron irradiation unit is further provided inside the reactor opposite to the coating area.

[0024] The neutron irradiation unit is a neutron source, and a laser neutron source can be used as the specific device.

[0025] In some embodiments, electrode plates for generating an accelerating electric field are further provided at both ends of the reactor, and the generated accelerating electric field intensity ranges from 500 V to 10 kV / m, and the direction of the accelerating electric field is the same as the direction of the carrier gas.

[0026] An electrode for generating a high-voltage electrostatic field is further provided at the gas outlet of the atomization unit.

[0027] Furthermore, the electric field electrode plates are arranged inside the sealing flange plates at both ends of the reactor to provide the accelerating electric field required to control the movement of the droplets.

[0028] The present invention also provides a method for fog chemical vapor deposition of large-size semiconductor thin films. This method uses the above-mentioned device for fog chemical vapor deposition of large-size semiconductor thin films, and includes the following steps:

[0029] S1. Fix the cleaned substrate on the rotating base, and then use the moving unit to move the substrate to face the second buffer plate in the coating area;

[0030] S2. Add the prepared reaction source solution to the atomization unit;

[0031] S3. Use nitrogen to evacuate the residual gas in the reactor and preheat it;

[0032] S4. After preheating, turn on the atomization unit, and the reaction source solution is atomized into uniform droplets;

[0033] S5. Introduce the carrier gas, and the carrier gas carries the droplets into the reactor, and a gallium oxide thin film grows on the substrate;

[0034] S6. After the growth of the gallium oxide thin film is completed, turn off the atomization device and the carrier gas and keep it warm; then turn on the carrier gas and continuously introduce it to evacuate the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and take out the sample.

[0035] Exemplarily, the method further includes: in S5, the film grows for 5 - 60 min, turn off the atomization device, turn on the neutron irradiation unit to irradiate the grown film with neutrons, the irradiation dose is set to 500 - 5000 kGy, the duration is 30 - 300 s, and keep heating for 3 - 15 min after the irradiation ends; this step is repeated 2 - 10 times;

[0036] Or the method further includes: after forming uniform droplets in S4, turn on the high - voltage electrostatic field to charge the droplets, the field strength of the high - voltage electrostatic field is 5 kV - 100 kV / m; at the same time, turn on the acceleration electric field, and the field strength of the acceleration electric field is 500 V - 10 kV / m.

[0037] The electrostatic field is the electric field that charges the droplets, the method of charging the droplets is induction charging, the high - voltage electrostatic field is an optional accessory for the atomization unit and is placed in the reactor. The droplets are positively charged, and the direction of the acceleration electric field is the same as the direction of the carrier gas.

[0038] Compared with the prior art, the large - size semiconductor thin - film aerosol chemical vapor deposition device and method of the present invention have the following advantages:

[0039] The large - size semiconductor thin - film aerosol chemical vapor deposition device of the present invention can realize the epitaxial growth of large - size (two - inch and above) gallium oxide thin films with uniform thickness in various crystal forms. In addition, the defect density of the film can be reduced after neutron irradiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0041] Figure 1 Schematic structural diagram of the large-size semiconductor thin film mist chemical vapor deposition device according to the embodiment of the present invention;

[0042] Figure 2 Schematic structural diagram of the horizontal large-size semiconductor thin film mist chemical vapor deposition device;

[0043] Figure 3 Schematic structural diagram of the vertical large-size semiconductor thin film mist chemical vapor deposition device;

[0044] Figure 4 The first structure of the deposition showerhead according to the embodiment of the present invention;

[0045] Figure 5 The second structure of the deposition showerhead according to the embodiment of the present invention;

[0046] Figure 6 Structural diagram of the rotating base according to the embodiment of the present invention;

[0047] Figure 7 The thin film prepared in Example 1 of the present invention;

[0048] Figure 8 The thin film prepared in Example 2 of the present invention;

[0049] Figure 9 Gas cross-sectional flow velocity distribution of the spray showerhead without a buffer structure;

[0050] Figure 10 Gas cross-sectional flow velocity distribution of the spray showerhead with a buffer structure in Example 1 of the present invention.

[0051] Explanation of reference numerals:

[0052] 1. Atomization unit; 2. Reactor; 21. Cylinder body; 22. Sealing flange plate; 221. Exhaust pipe; 222. Tail gas treatment unit; 23. Heating layer; 3. Buffer showerhead; 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 rod; 82. Slide bar; 83. Second motor; 84. Support seat; 9. Neutron irradiation unit. Detailed implementation manners

[0053] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0054] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0055] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] As Figure 1 shown, a large-size semiconductor thin film mist chemical vapor deposition device includes an atomization unit 1, a reactor 2, a buffer showerhead 3, and a rotating base 4;

[0058] The atomization unit 1 is used to atomize the reaction source solution to form droplets. The atomization means is not limited and can be atomization methods such as high-pressure airless atomization, gas atomization, ultrasonic atomization, and electrostatic atomization.

[0059] The reactor 2 provides the environmental conditions such as temperature and vacuum required for thin film epitaxial growth. The spatial position of the reactor 2 is not limited and can be horizontal, vertical, or inclined at any angle. For example, Figure 2 is a structural schematic diagram of a horizontal large-size semiconductor thin film mist chemical vapor deposition device, Figure 3It is a schematic structural diagram of a vertical large-size 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 degree range can be from 1×10 -4 Pa to multiple atmospheric pressures.

[0060] The material of the buffer showerhead 3 is a high-temperature resistant material, including but not limited to quartz, graphite, stainless steel, superalloy, etc.

[0061] The structure of the buffer showerhead 3 is as shown in Figure 4 and 5 shown. The buffer showerhead 3 is arranged inside the reactor 2. The buffer showerhead 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 - 600 mm. The delivery pipe 31 passes through one end of the reactor 2 and is connected to the atomization unit 1. The atomization unit 1 is also provided with a carrier gas input port; inside the cylindrical section 33, a first buffer plate 34 and a second buffer plate 35 are arranged in sequence from left to right. 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 apex of the conical plate structure can face the second buffer plate 35 or be 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 number of straight holes perpendicular to the second buffer plate 35, and the second buffer plate 35 is provided with a number 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.; in the coating area, a rotating base 4 facing the second buffer plate 35 is provided. The substrate is fixed on the rotating base 4. The substrate is surrounded by the cylindrical section 33 in 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 the moving unit, and the moving unit drives the first motor 6 and the rotating base 4 to move in a direction close to or away from the second buffer plate 35.

[0062] The substrate rotates with the rotating base 4. Under the action of the carrier gas, the mist droplets pass through the first buffer plate 34 and the second buffer plate 35 to reach the coating area, and thin film growth occurs on the substrate. When the mist droplets pass through the first buffer plate 34, the velocity distribution of the mist in the buffer area will quickly tend to be uniform. When the mist droplets 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 spray onto the substrate surface at a certain angle.

[0063] The opening size and shape of the delivery pipe 31 are not particularly limited. The shape can be circular, elliptical, rectangular, irregular shape, etc., and the opening inner diameter can be 10 - 300 mm.

[0064] As shown in Figure 2 and Figure 3As shown, dilution gas can also be introduced into the delivery pipe 31. The dilution gas can adjust the concentration of the mist, thereby affecting the growth rate to achieve the purpose of controlling the film thickness.

[0065] In some embodiments, the diameter of the straight holes is 2 - 10 mm, and the distance between every two adjacent straight holes is 2 - 5 mm; the diameter of the inclined holes is 2 - 10 mm.

[0066] The diameter of the straight holes is equal to the diameter of the inclined holes.

[0067] Preferably, the number of the inclined holes is equal to that of the straight holes and they are in one-to-one correspondence, and the one-to-one correspondence has less influence on the mist flow velocity.

[0068] The included angle between the central axis of the inclined holes and the surface normal of the second buffer plate 35 is 30 - 70°.

[0069] 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.

[0070] 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 included angle α of the vertex 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.

[0071] In some embodiments, the moving unit includes a moving seat 7 and a driving mechanism 8. The driving mechanism 8 includes a screw rod 81, a sliding rod 82, a second motor 83 and a support seat 84; the screw rod 81 and the sliding rod 82 are arranged in parallel on the support seat 84, the second motor 83 is in transmission connection with the screw rod 81, the moving seat 7 is slidably arranged on the sliding rod 82, and the moving seat 7 is threadedly connected with the screw rod 81, and the first motor 6 is installed on the moving seat 7.

[0072] In addition, the moving unit is not limited to the above structure, and any mechanism that can drive the moving seat 7 to move reciprocally can be applied to the present invention.

[0073] In some embodiments, the reactor 2 includes a cylindrical body 21 with openings at both ends and sealing flange plates 22 fixed at both ends of the cylindrical body 21. The delivery pipe 31 passes through one sealing flange plate 22, and the rotating base 4 and the rotating shaft 5 of the first motor 6 pass through the other sealing flange plate 22. An exhaust pipe 221 is also connected to the other sealing flange plate 22, and the exhaust pipe 221 is connected to the tail gas treatment unit 222; a heating layer 23 is also provided on the side wall of the cylindrical body 21.

[0074] The sealing flange plate 22 can be fixed by bolts or can also be fixed by a clamp.

[0075] The tail gas treatment unit 222 includes an alkaline scrubber bottle, an acidic scrubber bottle, and an adsorption bottle connected in sequence. The alkaline scrubber bottle contains an alkaline solution for removing acidic substances contained in the waste gas. The acidic scrubber bottle contains an acidic solution for removing alkaline substances contained in the waste gas. The adsorption bottle contains activated carbon and a desiccant for adsorbing other harmful substances in the waste gas.

[0076] In some embodiments, as Figure 6 shown, the side of the rotating base 4 facing the second buffer plate 35 is provided with a groove 41, and a boss 42 for placing the 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 with a top plate 44. The substrate is placed in the groove 41, and the top plate 44 is adjusted by adjusting the bolt 43 to clamp the substrate for fixation.

[0077] In addition, the structure for fixing the substrate is not limited to the above structure. It can also be a pressing piece provided on the rotating base 4, and the pressing piece is used to press on the surface of the substrate to fix the substrate; the substrate can also be fixed by a negative pressure adsorption method. There are air holes on the rotating base 4, and the rotating base 4 is connected to a negative pressure system.

[0078] In some embodiments, a neutron irradiation unit 9 is further provided inside the reactor 2 opposite to the coating area.

[0079] The neutron irradiation unit 9 is a neutron source, and a laser neutron source can be used as the specific equipment.

[0080] In some embodiments, electrode plates for generating an accelerating electric field are further provided at both ends of the reactor. The generated accelerating electric field intensity ranges from 500V to 10kV / m, and the direction of the accelerating electric field is consistent with the direction of the carrier gas.

[0081] The electrostatic field is an electric field that charges the droplets. The method for charging the droplets is induction charging. The high-voltage electrostatic field is generated by an electrode provided at the gas outlet of the atomization unit. The high-voltage electrostatic field intensity is 5kV to 100kV / m.

[0082] More specifically, the electric field electrode plates are arranged inside 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.

[0083] 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 (calculated as gallium) is specifically limited, and its range can be 0.005-0.5mol / L.

[0084] The carrier gas is not specifically limited. A mixed gas of an inert gas and O2 can be selected. Generally, nitrogen, which is relatively easy to obtain, is chosen as the inert gas. Adjusting the oxygen content in the mixed gas can change the proportion of chemical reaction products and also adjust the reaction rate. Adding oxygen can improve the crystal quality of the film to a certain extent. The adjustment of the reaction rate is reflected in that when the flow rate of the inert gas remains unchanged, after adding oxygen, the total flow rate of the carrier gas increases, the concentration of the mist decreases, and the film growth rate decreases.

[0085] The waste gas contains some incompletely reacted reactants and reaction products. Different reactants selected will make the waste gas contain alkaline or acidic substances. Most of the pollutants can be removed through two scrubbers, one for acid and one for alkali, and then the waste gas can be purified through an adsorption bottle. Connecting a negative pressure fan to the exhaust end of the waste gas treatment device can prevent the tail gas from being sucked back into the reaction chamber.

[0086] Example 1: Epitaxial growth of a two-inch α-Ga2O3 film on a sapphire substrate

[0087] This film is prepared by using a vertical large-size semiconductor film mist chemical vapor deposition device as shown in Figure 3 . On the basis of the above structure, in this example, the structure of the buffer showerhead 3 is as shown in Figure 4 . The diameter of the cylindrical section is 200 mm, the length is 300 mm, the diameter of the straight holes is 8 mm, the distance between every two adjacent straight holes is 4 mm, the diameter of the inclined holes is 8 mm, the straight holes and the inclined holes correspond one by one, and the included 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 shot at a 45° angle to the substrate surface; the distance from the center of the first buffer plate to the center of the second buffer plate is 100 mm; the included angle α of the top angle of the first buffer plate is 100°.

[0088] The method for preparing the film is as follows:

[0089] 1. Substrate cleaning

[0090] Place the sapphire substrate into an ultrasonic cleaner containing a cleaning solution and ultrasonically clean for 1 minute.

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

[0092] 2. Select a suitable quartz rotating base according to the substrate size, horizontally fix the sapphire substrate 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 2 mm directly above the second buffer plate and the substrate is parallel to the second buffer plate.

[0094] 4. Preparation of the reaction source solution: Dissolve 18.5 grams of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution with a concentration of approximately 0.025 mol / L, and add the prepared reaction source solution to the atomization unit.

[0095] 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. Set the reactor temperature to 650 °C.

[0096] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit, and the ultrasonic atomization frequency is 3 MHz.

[0097] 7. Introduce the carrier gas. The carrier gas is nitrogen with a flow rate of 400 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide thin film on the substrate; the reactor maintains the growth temperature and starts to grow the gallium oxide thin film. Set the growth time to 30 min.

[0098] 8. After the growth of the gallium oxide thin film is completed, turn off the atomization device and the carrier gas and keep it warm for 3 minutes. Then turn on the carrier gas and continuously introduce nitrogen to evacuate the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and take out the sample.

[0099] Figure 7 For the two-inch thin film sample prepared in this example, the thickness of the tested part in the figure is 1020 nm. Randomly select 20 points on the prepared thin film to measure its thickness. The average thickness is 1018 nm, and the thickness standard deviation is only 26 nm, indicating that a gallium oxide thin film with a relatively uniform thickness can be prepared by using the device described in the present invention.

[0100] Example 2 Epitaxial Growth of Four-inch α-Ga2O3 Thin Film on Sapphire Substrate

[0101] This thin film is prepared by using the same vertical large-size semiconductor thin film aerosol chemical vapor deposition device as in Example 1.

[0102] The method for preparing the thin film is as follows:

[0103] 1. Substrate cleaning

[0104] Place the sapphire substrate in an ultrasonic cleaner containing a cleaning solution and ultrasonically clean it for 1 min.

[0105] Take out the substrate and use nitrogen to dry the cleaning solution remaining on the surface of the substrate.

[0106] 2. Select a suitable quartz rotating base according to the substrate size, horizontally fix the sapphire substrate 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.

[0107] 3. Adjust the rotating base so that the substrate is 2 mm directly above the second buffer plate, and the substrate is parallel to the second buffer plate.

[0108] 4. Prepare the reaction source solution: Dissolve 18.5 grams of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution with a concentration of approximately 0.025 mol / L, and add the prepared reaction source solution to the atomization unit.

[0109] 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. Set the reactor temperature to 650 °C.

[0110] 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.

[0111] 7. Introduce the carrier gas. The carrier gas is nitrogen with a flow rate of 800 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide thin film on the substrate. The reactor maintains the growth temperature and starts growing the gallium oxide thin film. Set the growth time to 30 min.

[0112] 8. After the growth of the gallium oxide thin film is completed, turn off the atomization device and the carrier gas and keep it warm for 3 minutes. Then turn on the carrier gas and continuously introduce nitrogen to evacuate the residual reactants and by-products in the reaction chamber and slowly cool it to room temperature, and take out the sample.

[0113] Figure 8 For the four-inch thin film sample prepared in this example, the thickness of the tested part in the figure is 740 nm. Randomly select 20 points on the prepared thin film to measure its thickness. The average thickness is 742 nm, and the thickness standard deviation is only 43 nm, indicating that a gallium oxide thin film with relatively uniform thickness can be prepared by using the device described in the present invention.

[0114] Example 3 Epitaxial growth of two-inch ε-Ga2O3 thin film on sapphire substrate

[0115] This thin film is prepared by using the same vertical large-size semiconductor thin film mist chemical vapor deposition device as in Example 1, but the inclination angle of the inclined holes is different. The included angle between the central axis of the inclined holes and the surface normal of the second buffer plate is 65°, so that the raw material mist is shot at the substrate surface at an angle of 65°.

[0116] The method for preparing the thin film is as follows:

[0117] 1. Substrate cleaning

[0118] Place the sapphire substrate into an ultrasonic cleaner containing cleaning solution and ultrasonically clean it for 1 min.

[0119] Take out the substrate and use nitrogen to dry the cleaning solution remaining on the substrate surface.

[0120] 2. Select a suitable quartz rotating base according to the substrate size, horizontally fix the sapphire substrate 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.

[0121] 3. Adjust the rotating base so that the substrate is 10 mm directly above the second buffer plate, and the substrate is parallel to the second buffer plate.

[0122] 4. Preparation of the reaction source solution: Dissolve 18.5 grams 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.

[0123] 5. Use nitrogen to evacuate the residual gas in the reactor and perform preheating. The reactor temperature is set to 850 °C.

[0124] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit, and the ultrasonic atomization frequency is 3 MHz.

[0125] 7. Introduce the carrier gas. The carrier gas is nitrogen with a flow rate of 600 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide thin film on the substrate; the reactor maintains the growth temperature and starts to grow the gallium oxide thin film. The growth time is set to 30 min.

[0126] 8. After the growth of the gallium oxide thin film is completed, turn off the atomization device and the carrier gas and keep it warm for 3 minutes. Then turn on the carrier gas and continuously introduce nitrogen to evacuate the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and take out the sample.

[0127] Through measurement, a gallium oxide thin film with relatively uniform thickness is also prepared in this embodiment.

[0128] Example 4 Epitaxial growth of a two-inch β-Ga2O3 thin film on a β-Ga2O3 substrate

[0129] This thin film is prepared by using the same vertical large-size semiconductor thin film aerosol chemical vapor deposition device as in Example 1.

[0130] The method for preparing the thin film is as follows:

[0131] 1. Substrate cleaning

[0132] Place the β-Ga2O3 substrate into an ultrasonic cleaner containing cleaning solution and ultrasonically clean for 1 min.

[0133] Take out the substrate and use nitrogen to blow dry the cleaning solution remaining on the surface of the substrate.

[0134] 2. Select a suitable quartz rotating base according to the substrate size, horizontally fix the sapphire substrate 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.

[0135] 3. Adjust the rotating base so that the substrate is 2 mm directly above the second buffer plate, and the substrate is parallel to the second buffer plate.

[0136] 4. Preparation of the reaction source solution: Dissolve 18.5 grams 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.

[0137] 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 950 °C.

[0138] 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.

[0139] 7. Introduce the carrier gas. The carrier gas is nitrogen with a flow rate of 2000 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide thin film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide thin film. The growth time is set to 30 min.

[0140] 8. After the growth of the gallium oxide thin film is completed, turn off the atomization device and the carrier gas and keep it warm for 3 minutes. Then turn on the carrier gas and continuously introduce nitrogen to evacuate the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and take out the sample.

[0141] Through measurement, a gallium oxide thin film with relatively uniform thickness is also prepared in this embodiment.

[0142] Example 5 Epitaxial Growth of Two-inch α-Ga2O3 Thin Film on Sapphire Substrate Induced by Neutron Radiation

[0143] This thin film is prepared by using the same vertical large-size 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 directly opposite the coating area. The neutron irradiation unit is a neutron source, and a laser neutron source can be used as the specific equipment.

[0144] The method for preparing the thin film is as follows:

[0145] 1. Substrate cleaning

[0146] Place the sapphire substrate into an ultrasonic cleaner containing cleaning solution and ultrasonically clean it for 1 min.

[0147] Take out the substrate and use nitrogen to dry the cleaning solution remaining on the surface of the substrate.

[0148] 2. Select a suitable quartz rotating base according to the substrate size, horizontally fix the sapphire substrate 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.

[0149] 3. Adjust the rotating base so that the substrate is 2 mm directly above the second buffer plate and the substrate is parallel to the second buffer plate.

[0150] 4. Prepare the reaction source solution. Dissolve 18.5 grams of gallium acetylacetonate powder in 2 liters of deionized water to prepare a gallium source solution of approximately 0.025 mol / L, and add the prepared reaction source solution to the atomization unit.

[0151] 5. Use nitrogen to evacuate the residual gas in the reactor and preheat it. The reactor temperature is set to 650 °C.

[0152] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets by ultrasonic atomization in the atomization unit, and the ultrasonic atomization frequency is 3 MHz.

[0153] 7. Introduce the carrier gas. The carrier gas is nitrogen with a flow rate of 400 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide thin film on the substrate. The reactor maintains the growth temperature and starts to grow the gallium oxide thin film. The growth time is set to 10 min.

[0154] 8. After that, turn off the atomization unit, turn on the neutron irradiation unit to irradiate the grown thin film with neutrons. The irradiation dose is set to 100 kGy and the duration is 2 min. After the irradiation, keep heating for 10 min.

[0155] 9. Repeat steps 7 and 8 five times.

[0156] 10. After the growth of the gallium oxide thin film is completed, turn off the atomization device and the carrier gas and keep the temperature for 3 minutes. Then turn on the carrier gas and continuously introduce nitrogen to evacuate the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and take out the sample.

[0157] Compared with Example 1, the defect density of the thin film prepared in this example is reduced, and the thickness uniformity of the thin film changes little.

[0158] Epitaxial growth of two-inch α-Ga2O3 thin film on sapphire substrate under additional electric field environment in Example 6

[0159] This thin film is prepared by using the same vertical large-size semiconductor thin film mist chemical vapor deposition device as in Example 1. On the basis of the device in Example 1, electrode plates for generating an accelerating electric field are also provided at both ends of the reactor of this device. The direction of the accelerating electric field is the same as 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.

[0160] The method for preparing the thin film is as follows:

[0161] 1. Substrate cleaning

[0162] Place the sapphire substrate into an ultrasonic cleaner containing a cleaning solution and ultrasonically clean for 1 min.

[0163] Take out the substrate and use nitrogen to blow dry the cleaning solution remaining on the surface of the substrate.

[0164] 2. Select a suitable quartz rotating base according to the substrate size, horizontally fix the sapphire substrate 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.

[0165] 3. Adjust the rotating base so that the substrate is 2 mm directly above the second buffer plate and the substrate is parallel to the second buffer plate.

[0166] 4. Preparation of the reaction source solution: Dissolve 18.5 grams 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;

[0167] 5. Use nitrogen to evacuate the residual gas in the reactor and perform preheating. The temperature of the reactor is set at 650 °C.

[0168] 6. After preheating, turn on the atomization unit. The reaction source is atomized into uniform droplets in the atomization unit by ultrasonic atomization method, and the ultrasonic atomization frequency is 3 MHz.

[0169] 7. Turn on the high-voltage electrostatic field to charge the droplets. The field strength of the high-voltage electrostatic field is 10 kV / m.

[0170] At the same time, turn on the acceleration electric field. The field strength of the acceleration electric field is 1 kV / m.

[0171] 8. Introduce the carrier gas. The carrier gas is nitrogen with a flow rate of 200 sccm. The carrier gas carries the droplets into the reactor and grows a gallium oxide thin film on the substrate; the reactor maintains the growth temperature and starts to grow the gallium oxide thin film. The growth time is set at 30 min.

[0172] 9. After the growth of the gallium oxide thin 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 continuously introduce nitrogen to evacuate the residual reactants and by-products in the reaction chamber and slowly cool down to room temperature, and take out the sample.

[0173] Compared with Example 1, the growth rate of the thin film prepared in this example is improved, the thickness of the thin film increases, and the thickness uniformity changes little.

[0174] Therefore, by using the device proposed in the present invention, gallium oxide thin films with different thicknesses can be grown by changing the growth time, gallium oxide thin films with different crystal forms can be grown by changing the growth temperature of the reaction chamber, and homoepitaxial and heteroepitaxial gallium oxide thin films can be realized by using different substrates respectively.

[0175] Comparative Example 1 Angle of inclination of the inclined holes

[0176] 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 shoots at the substrate surface at an angle of 5°.

[0177] The uniformity of the obtained thin film is worse than that of Example 1, and there are periodic thickness fluctuations in the thin film, indicating that the angle cannot be too small.

[0178] Comparative Example 2 Angle of inclination of the inclined holes

[0179] 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 shoots at the substrate surface at an angle of 80°.

[0180] The thickness uniformity of the obtained thin film is slightly worse than that of Example 1, and the average thickness is thinner than that of Example 1, indicating that when the angle is too large, it is not conducive to the growth of the thin film.

[0181] Comparative Example 3 Spacing between holes

[0182] Compared with Example 1, the difference is that the distance between every two adjacent straight holes is 15 mm.

[0183] The thickness uniformity of the obtained thin film becomes worse. The increase in the hole spacing actually leads to a decrease in the hole density, making the thin film thickness uneven.

[0184] Comparative Example 4 Diameter of the holes

[0185] 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.

[0186] The thickness uniformity of the obtained thin film becomes worse. The too large hole diameter leads to a poor buffering effect and the thin film thickness becomes uneven.

[0187] Comparative Example 5 Setting of the buffer plate

[0188] Compared with Example 1, the difference is that there is only the second buffer plate.

[0189] The uniformity of the thin film becomes worse, and the edge of the thin film becomes thinner. This is caused by the uneven distribution of the mist flow velocity due to the lack of the first buffer plate.

[0190] Comparative Example 6 Without buffer plate

[0191] 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 the extreme case of the large holes in Comparative Example 4, that is, the hole diameter is equal to the diameter of the cylindrical section, that is, there are no two buffer plates).

[0192] The thickness uniformity of the obtained thin film becomes worse.

[0193] Figure 9 This is the cross-sectional gas flow velocity distribution of the gas ejected from the spray showerhead without a buffer structure in this comparative example; Figure 10 This is the cross-sectional gas flow velocity distribution of the gas ejected from the spray showerhead with a buffer structure in Example 1. It can be seen from the figure that the mist flow velocity is more uniform with a buffer structure, so that a thin film with a more uniform thickness can be obtained.

[0194] In summary, the large-size semiconductor thin film mist chemical vapor deposition device proposed by the present invention is provided with a buffer showerhead in the reactor. By designing the structure of the buffer showerhead, epitaxial growth of large-size and thickness-uniform gallium oxide thin films of various crystal forms can be realized.

[0195] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall 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 atomizing unit, and the atomizing 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 cone top of the conical plate structure is far away from the second buffer plate, and the first buffer plate is provided with a plurality of straight holes perpendicular to the second buffer plate, and the second buffer plate is provided with a plurality of oblique holes; a rotating base which is directly opposite to the second buffer plate is provided 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 in a direction close to or away from the second buffer plate; 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°.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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 7, 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.

9. The method for mist chemical vapor deposition of a large-scale semiconductor thin film according to claim 8, 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.

Images