Chemical vapor deposition equipment and method for preparing silicon carbide epitaxial layer

Abstract

The present invention provides a chemical vapor deposition (CVD) apparatus, comprising: a sample preparation chamber, an operation chamber, a reaction chamber, and a sampling chamber. The sample preparation chamber is adapted to provide a space for placing trays loaded with substrate wafers; the operation chamber comprises: a manipulator and an air trap, wherein the manipulator is adapted to grab the trays in the sample preparation chamber and transport them to the corresponding reaction chamber; the air trap is adapted to exhaust the gas entering the operation chamber; the reaction chamber comprises: a plurality of growth chambers and a transfer chamber, wherein the plurality of growth chambers are adapted to provide reaction spaces for growing corresponding epitaxial layers; the transfer chamber is adapted to provide temporary storage space for the plurality of trays when the corresponding epitaxial layers are grown simultaneously in the plurality of growth chambers; the sampling chamber is adapted to place trays loaded with wafers after the reaction is completed; the operation chamber is configured to be located at the center of the CVD apparatus, and the other chambers are configured to be located around the operation chamber; the operation chamber and the other chambers are connected via valves.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical vapor deposition equipment and manufacturing silicon carbide epitaxial wafers, and in particular to a chemical vapor deposition equipment and a method for preparing a silicon carbide epitaxial layer. Background Art

[0002] Chemical vapor deposition (CVD) is a widely used technology in semiconductor fabrication. By introducing one or more gas sources into a reaction chamber, single crystal or polycrystalline thin films are grown or deposited on the corresponding substrate surface under set reaction conditions.

[0003] Traditional chemical vapor deposition equipment uses a single-chamber structure to achieve the preparation of multiple epitaxial layers in the same chamber. Since the preparation conditions of epitaxial layers doped with different elements are different, during the preparation of multi-layer epitaxial layers, there are multiple gas sources in the reaction environment that interfere with each other, thereby affecting the purity and quality of the prepared epitaxial layers. In addition, due to its single-chamber structure, traditional chemical vapor deposition equipment cannot grow multiple epitaxial layers at the same time: that is, after the growth of a certain epitaxial layer is completed, the reaction atmosphere must be adjusted to prepare subsequent layers, making the preparation efficiency of multi-layer epitaxial layers low. Summary of the Invention

[0004] In view of the above problems, the present invention provides a chemical vapor deposition device, comprising:

[0005] A sample preparation room, adapted to provide space for placing trays loaded with substrate wafers;

[0006] Operating room, including:

[0007] A manipulator, adapted to automatically grab the tray in the sample preparation room and transport it to the corresponding reaction chamber;

[0008] A gas trap suitable for evacuating the gas entering the above-mentioned operating room;

[0009] The reaction chamber comprises:

[0010] The first growth chamber is adapted to provide a reaction space for growing a buffer layer;

[0011] The second growth chamber is suitable for providing a reaction space for growing an N-type epitaxial layer;

[0012] A third growth chamber, adapted to provide a reaction space for growing a P-type epitaxial layer; and

[0013] The transfer chamber is adapted to provide temporary storage space for the plurality of trays when corresponding epitaxial layers are grown simultaneously in the first growth chamber, the second growth chamber, and the third growth chamber;

[0014] A sampling chamber suitable for placing trays loaded with wafers after reaction;

[0015] The operation chamber is arranged at the center of the chemical vapor deposition equipment, and the sample preparation chamber, the reaction chamber and the sampling chamber are arranged around the operation chamber; the operation chamber is connected to other chambers via valves.

[0016] According to an embodiment of the present invention, the sample preparation chamber, the reaction chamber and the sampling chamber are configured as vacuum chambers; the plurality of vacuum chambers are respectively provided with independent gas inlets and gas outlets; the plurality of gas outlets are connected to stainless steel gas pipes and connected in parallel, and the reaction residual gas is pumped to the tail gas tower through a vacuum pump.

[0017] According to an embodiment of the present invention, the material of the above-mentioned robot is one of graphite and silicon carbide ceramics; the above-mentioned robot has the function of moving along three directions of X axis, Y axis and Z axis respectively.

[0018] According to an embodiment of the present invention, the above-mentioned robot includes an elastic rope box, an elastic rope storage wheel, a motor and a movable finger plate; the above-mentioned elastic rope box is suitable for placing the elastic rope; the above-mentioned movable finger plate is equipped with multiple groups of movable fingers; wherein, under the drive of the above-mentioned motor, the above-mentioned elastic rope storage wheel tightens the elastic rope, so that the above-mentioned movable finger drives the spring to move toward the axis center, and then grabs the tray loaded with wafers; after the motor is removed, the above-mentioned spring contracts, driving the above-mentioned movable finger to move in a direction away from the axis center, and then releases the above-mentioned tray loaded with wafers.

[0019] According to an embodiment of the present invention, an air trap comprises: an upper portion and a lower portion;

[0020] The above-mentioned upper part includes:

[0021] The entire surface is provided with air inlets, which are suitable for providing an inlet for introducing inert gas into the above-mentioned operating room;

[0022] a first isolation wall, arranged to connect with the outer wall of each vacuum chamber, adapted to block the inert gas introduced through the gas inlet, so that the inert gas can move vertically downward;

[0023] The above lower part includes:

[0024] A gas trap is provided at the bottom of the operating chamber and is configured in an annular shape, and is suitable for collecting the reaction residual gas entering the operating chamber from the plurality of vacuum chambers;

[0025] a second isolation wall, disposed at a position corresponding to the first isolation wall, adapted to isolate the reaction residual gas entering the operating chamber from the plurality of vacuum chambers;

[0026] The return air hole is arranged in the above-mentioned gas trap and is configured to be connected to the above-mentioned vacuum pump, thereby realizing the extraction of the above-mentioned reaction residual gas entering the operating room into the tail gas tower; wherein, a plurality of the above-mentioned return air holes are arranged between two adjacent above-mentioned second isolation walls.

[0027] Another aspect of the present invention discloses a method for preparing a silicon carbide epitaxial layer, which is applied to any of the above-mentioned devices, comprising:

[0028] Transporting the tray loaded with substrate wafers from the sample preparation room to the operation room;

[0029] Using a robot to grab the tray from the operating chamber and transport it to the first growth chamber to grow a buffer layer on the substrate wafer;

[0030] When the buffer layer is grown in the first growth chamber, the tray is grabbed from the operation chamber by the robot and transported to the second growth chamber to grow an N-type epitaxial layer on the buffer layer.

[0031] When the N-type epitaxial layer is grown in the second growth chamber, the tray is picked up from the operation chamber by the robot and transported to a third growth chamber to grow a P-type epitaxial layer on the N-type epitaxial layer.

[0032] When the P-type epitaxial layer is grown in the third growth chamber, the tray is grabbed from the operating chamber by a robot and transported to a sampling chamber to complete the preparation of the silicon carbide epitaxial layer.

[0033] When corresponding epitaxial layers are grown simultaneously in the first growth chamber, the second growth chamber, and the third growth chamber, the robot arm is used to grab a plurality of the trays and temporarily store them in the transfer chamber.

[0034] According to an embodiment of the present invention, a robot is used to grab the tray from the operating chamber and transport it to the first growth chamber to grow a buffer layer on the substrate wafer, including:

[0035] Adjusting the temperature and pressure of the first growth chamber to set values, and introducing a first growth gas from the gas inlet of the first growth chamber; wherein the first growth gas includes a silicon source gas, a carbon source gas, and a buffer source gas;

[0036] When the pressure in the first growth chamber is stable and equal to the pressure in the operation chamber, opening the second valve between the first growth chamber and the operation chamber;

[0037] Using the manipulator to grab the tray in the operation chamber and move it to the first growth chamber, then retracting the manipulator and closing the second valve;

[0038] After the buffer layer of the set thickness is grown in the first growth chamber, the second valve is opened, the tray is grabbed from the first growth chamber to the operation chamber by the robot, and the second valve is closed.

[0039] According to an embodiment of the present invention, when the buffer layer is grown in the first growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a second growth chamber to grow an N-type epitaxial layer on the buffer layer, including:

[0040] Adjusting the temperature and pressure of the second growth chamber to set values, and introducing a second growth gas from the gas inlet of the second growth chamber; wherein the second growth gas includes a silicon source gas, a carbon source gas, and an N-type dopant source gas;

[0041] When the pressure in the second growth chamber is stable and equal to the pressure in the operation chamber, opening a third valve between the second growth chamber and the operation chamber;

[0042] Using the manipulator to grab the tray in the operation chamber and move it to the second growth chamber, then retracting the manipulator and closing the third valve;

[0043] After the N-type epitaxial layer of the set thickness is grown in the second growth chamber, the third valve is opened, the tray is grabbed from the second growth chamber to the operation chamber by the robot, and the third valve is closed.

[0044] According to an embodiment of the present invention, when the N-type epitaxial layer is grown in the second growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a third growth chamber to grow a P-type epitaxial layer on the N-type epitaxial layer, including:

[0045] Adjusting the temperature and pressure of the third growth chamber to set values, and introducing a third growth gas from the gas inlet of the third growth chamber; wherein the third growth gas includes a silicon source gas, a carbon source gas, and a P-type dopant source gas;

[0046] When the pressure in the third growth chamber is stable and equal to the pressure in the operation chamber, opening a fourth valve between the third growth chamber and the operation chamber;

[0047] Using the manipulator to grab the tray in the operation chamber and move it to the third growth chamber, then retracting the manipulator and closing the fourth valve;

[0048] After the P-type epitaxial layer of the set thickness is grown in the third growth chamber, the fourth valve is opened, the tray is grabbed from the third growth chamber to the operation chamber by the robot, and the fourth valve is closed.

[0049] According to an embodiment of the present invention, the method for preparing a silicon carbide epitaxial layer further includes:

[0050] S1: transport the tray loaded with substrate wafers from the sample preparation room to the operation room;

[0051] S2: using a robot to grab the tray from the operating chamber and transport it to the first growth chamber to grow a buffer layer on the substrate wafer;

[0052] S3: When the buffer layer is grown in the first growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a second growth chamber to grow a first N-type epitaxial layer on the buffer layer.

[0053] S4: When the growth of the first N-type epitaxial layer is completed in the second growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a third growth chamber to grow a first P-type epitaxial layer on the N-type epitaxial layer.

[0054] S5: When the growth of the first P-type epitaxial layer is completed in the third growth chamber, the tray is grabbed from the operation chamber by a robot and transported to the second growth chamber to grow a second N-type epitaxial layer on the first P-type epitaxial layer;

[0055] S6: When the second N-type epitaxial layer is grown in the second growth chamber, a robot is used to grab the tray from the operation chamber and transport it to a third growth chamber to grow a second P-type epitaxial layer on the second N-type epitaxial layer.

[0056] S7: Repeat S5 to S6 multiple times according to the doping conditions of the silicon carbide epitaxial layer.

[0057] According to an embodiment of the present invention, the apparatus employs a multi-chamber structure, each of which can perform an independent function or be connected in series to perform the functions of a composite structure. Therefore, the method for fabricating a silicon carbide epitaxial layer can be performed independently or in series.

[0058] According to embodiments of the present invention, the equipment utilizes a multi-chamber structure, with each chamber operating in a stable state and performing a single function. This prevents crosstalk between multiple gas sources, such as N and P dopant sources, and memory effects, thereby improving the purity and quality of the epitaxial layer. Furthermore, switching from one epitaxial growth process to another can be done without waiting, thus preserving the epitaxial surface of the wafer. This improves the quality of the epitaxial layer and reduces the generation of impurities and defects.

[0059] According to an embodiment of the present invention, the equipment adopts a multi-chamber structure, which transfers wafers between various process steps by switching valves, and can complete the epitaxial layer preparation in a short period of time. Unlike a single-chamber structure, it does not require a certain amount of time to switch between each process, thereby increasing the total process completion time. In addition, multiple growth chambers can also work independently and simultaneously to complete the epitaxial layer preparation of multiple wafers, thereby improving the preparation efficiency of the epitaxial layer of the multi-layer structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0061] Figure 1 A schematic diagram of a chemical vapor deposition device according to an embodiment of the present invention is shown;

[0062] Figure 2 A schematic diagram of a manipulator according to an embodiment of the present invention is shown schematically;

[0063] Figure 3 Schematically shows a schematic diagram of an air trap according to an embodiment of the present invention;

[0064] Figure 4 The flowchart of the method for preparing a silicon carbide epitaxial layer according to an embodiment of the present invention is schematically shown;

[0065] Figure 5 The flowchart of the method for preparing a silicon carbide epitaxial layer according to another embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0066] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0067] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0068] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0069] When expressions such as "at least one of A, B and C, etc." are used, they should generally be interpreted in accordance with the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0070] Figure 1 The figure schematically shows a chemical vapor deposition device according to an embodiment of the present invention.

[0071] An exemplary embodiment of the present invention provides a chemical vapor deposition apparatus, see Figure 1 As shown, it includes: a sample preparation chamber, an operation chamber, a reaction chamber, and a sampling chamber. The sample preparation chamber is suitable for providing space for placing trays loaded with substrate wafers. The operation chamber includes: a robot and an air trap. The robot is suitable for automatically grabbing trays in the sample preparation chamber and transporting them to the corresponding reaction chamber. The air trap is suitable for exhausting gas entering the operation chamber. The reaction chambers include: a first growth chamber, a second growth chamber, a third growth chamber, and a transfer chamber. The first growth chamber is suitable for providing a reaction space for growing a buffer layer; the second growth chamber is suitable for providing a reaction space for growing an N-type epitaxial layer; the third growth chamber is suitable for providing a reaction space for growing a P-type epitaxial layer; and the transfer chamber is suitable for providing temporary storage space for multiple trays while the corresponding epitaxial layers are grown simultaneously in the first, second, and third growth chambers. The sampling chamber is suitable for placing trays loaded with wafers after reactions have completed. The operation chamber is configured to be located in the center of the chemical vapor deposition equipment, and the sample preparation chamber, reaction chamber, and sampling chamber are configured to be located around the operation chamber. The operation chamber is connected to the other chambers via valves.

[0072] According to an embodiment of the present invention, the apparatus employs a multi-chamber structure, each chamber of which can perform an independent function or be connected in series to perform the functions of a composite structure. This allows the silicon carbide epitaxial layer fabrication method to be performed independently or in series, making the method simple, easy to implement, and readily scalable.

[0073] According to embodiments of the present invention, the equipment utilizes a multi-chamber structure, in which each chamber is stable and performs a single function. This prevents crosstalk between multiple gas sources, such as N and P dopant sources, and memory effects, thereby improving the purity and quality of the epitaxial layer. Furthermore, switching from one epitaxial growth process to another can be done without waiting, thus preserving the epitaxial surface of the wafer. This improves the quality of the epitaxial layer and reduces the generation of impurities and defects.

[0074] According to an embodiment of the present invention, the equipment adopts a multi-chamber structure, which transfers wafers between various process steps by switching valves, and can complete the epitaxial layer preparation in a short period of time. Unlike a single-chamber structure, it does not require a certain amount of time to switch between each process, thereby increasing the total process completion time. In addition, multiple growth chambers can also work independently and simultaneously to complete the epitaxial layer preparation of multiple wafers, thereby improving the preparation efficiency of the epitaxial layer of the multi-layer structure.

[0075] According to an embodiment of the present invention, the gas trap is suitable for exhausting the gas entering the operating chamber. That is, when the operating chamber interacts with the first growth chamber, the second growth chamber and the third growth chamber respectively, the gas entering the operating chamber is discharged through the gas trap, ensuring that the operating chamber is not contaminated by the participating gases.

[0076] According to an embodiment of the present invention, the sample preparation room, reaction chamber and sampling chamber are configured as vacuum chambers; multiple vacuum chambers are respectively configured with independent gas inlets and gas outlets; multiple gas outlets are connected in parallel with stainless steel gas pipes, and the residual reaction gas is pumped to the tail gas tower through a vacuum pump and emptied after treatment.

[0077] According to an embodiment of the present invention, the device adopts a multi-chamber structure, avoiding the disadvantages of the single-chamber structure of traditional equipment: since the source gas, temperature, pressure and other process parameters of the buffer layer, N-type and P-type epitaxial processes are different from each other, when growing the corresponding epitaxial layer in a single chamber, it is necessary to switch to the corresponding reaction atmosphere each time and wait for a certain period of time before reaching a stable state; and during this waiting process, there is no protection measure on the epitaxial surface of the wafer, making it extremely susceptible to interference, causing damage to the epitaxial surface.

[0078] According to an embodiment of the present invention, the device adopts a multi-chamber structure, and each chamber in the multi-chamber structure is in a stable state and only performs a single function, thereby avoiding crosstalk between multiple gas sources, such as crosstalk and memory effect of N and P doping sources, and improving the purity and quality of the epitaxial layer.

[0079] Figure 2 The figure schematically shows a schematic diagram of a manipulator according to an embodiment of the present invention.

[0080] Figure 2Figure (a) shows the side view of the manipulator. Figure 2 Figure (b) shows a top view of the movable finger plate.

[0081] like Figure 2 As shown, the robot arm includes an elastic cord box, an elastic cord storage wheel, a motor, and a movable finger plate. The elastic cord box is used to store the elastic cord. The movable finger plate is equipped with multiple sets of movable fingers. Driven by the motor, the elastic cord storage wheel tightens the elastic cord, causing the movable fingers to drive the spring toward the axis and grasp the tray loaded with wafers. When the motor is removed, the spring contracts, driving the movable fingers away from the axis, thereby releasing the tray loaded with wafers. By repeatedly turning the motor on and off, the robot arm can repeatedly grasp the tray loaded with wafers.

[0082] According to an embodiment of the present invention, preferably, two adjacent groups of movable fingers form an angle of 90 degrees, so as to achieve smooth grasping of the tray loaded with wafers.

[0083] According to an embodiment of the present invention, the material of the manipulator is one of graphite and silicon carbide ceramics, and the elastic rope is a carbon rope, both of which can withstand high temperatures up to 1650°C; the manipulator has the function of moving along the X-axis, Y-axis and Z-axis respectively.

[0084] Figure 3 A schematic diagram of an air trap according to an embodiment of the present invention is shown schematically.

[0085] Figure 3 Figure (a) shows the side view of the air trap. Figure 3 Figure (b) shows the bottom view of the air trap. Figure 3 Figure (c) shows a top view of the air trap.

[0086] like Figure 3 As shown, the air trap includes: an upper part and a lower part; the upper part includes: air inlet holes laid on the entire surface, suitable for providing an entrance for passing inert gas into the operating chamber; a first isolation wall, arranged in connection with the outer wall of each vacuum chamber, suitable for blocking the inert gas passed through the air inlet, so that the inert gas can move vertically downward; the lower part includes: an air trap groove, arranged at the bottom of the operating chamber and configured in a ring shape, suitable for gathering reaction residual gases entering the operating chamber from multiple vacuum chambers; a second isolation wall, suitable for isolating reaction residual gases entering the operating chamber from multiple vacuum chambers; return air holes, the return air holes are arranged in the air trap groove, and are configured to be connected to the vacuum pump, thereby realizing the extraction of the reaction residual gases entering the operating chamber to the tail gas tower; wherein, multiple return air holes are arranged between two adjacent second isolation walls.

[0087] According to an embodiment of the present invention, the inert gas moves vertically downward, thereby applying a downward pressure to the reaction residual gas entering the operating chamber, so that the residual gas is confined in the gas trap and is drawn away by the vacuum pump through multiple return holes, thereby realizing the function of emptying the residual gas in the operating chamber.

[0088] Figure 4 The flowchart of the method for preparing a silicon carbide epitaxial layer according to an embodiment of the present invention is schematically shown.

[0089] like Figure 4 As shown, the method for preparing a silicon carbide epitaxial layer may include steps S401 to S405.

[0090] In operation S401 , a tray loaded with substrate wafers is transported from a sample preparation room to an operation room using a robot arm.

[0091] According to an embodiment of the present invention, a tray loaded with substrate wafers is transported from a sample preparation room to an operation room using a robot, including:

[0092] Place the tray loaded with substrate wafers into the corresponding position in the sample preparation room;

[0093] After repeated vacuuming, flush the sample preparation chamber with inert gas;

[0094] Open the first valve between the sample preparation room and the operation room;

[0095] After the tray in the sample preparation room is grabbed by the manipulator and brought to the operation room, the first valve is closed to complete the state of waiting for sample loading.

[0096] In operation S402, a robot arm is used to grab a tray from an operating chamber and transport it to a first growth chamber to grow a buffer layer on the substrate wafer.

[0097] According to an embodiment of the present invention, a tray is grabbed from an operating chamber by a robot and transported to a first growth chamber to grow a buffer layer on a substrate wafer, including:

[0098] Adjusting the temperature and pressure of the first growth chamber to set values, and introducing the first growth gas from the gas inlet of the first growth chamber; wherein the first growth gas includes silicon source gas, carbon source gas, and buffer source gas;

[0099] When the pressure in the first growth chamber is stable and equal to the pressure in the operation chamber, opening the second valve between the first growth chamber and the operation chamber;

[0100] Using a manipulator to grab the tray in the operating chamber and move it to the first growth chamber, then returning the manipulator and closing the second valve;

[0101] After the buffer layer of the set thickness is grown in the first growth chamber, the second valve is opened, the tray is grabbed from the first growth chamber to the operation chamber by a robot, and the second valve is closed to complete the buffer layer growth state.

[0102] In operation S403 , when the buffer layer growth is completed in the first growth chamber, a tray is grabbed from the operation chamber by a robot and transported to a second growth chamber to grow an N-type epitaxial layer on the buffer layer.

[0103] According to an embodiment of the present invention, when the buffer layer growth is completed in the first growth chamber, a tray is grabbed from the operation chamber by a robot and transported to the second growth chamber to grow an N-type epitaxial layer on the buffer layer, including:

[0104] Adjusting the temperature and pressure of the second growth chamber to set values, and introducing a second growth gas from the gas inlet of the second growth chamber; wherein the second growth gas includes a silicon source gas, a carbon source gas, and an N-type dopant source gas;

[0105] When the pressure in the second growth chamber is stable and equal to the pressure in the operation chamber, opening the third valve between the second growth chamber and the operation chamber;

[0106] Using a manipulator to grab the tray in the operating chamber and move it to the second growth chamber, then returning the manipulator and closing the third valve;

[0107] After the N-type epitaxial layer of the set thickness is grown in the second growth chamber, the third valve is opened, the tray is grabbed from the second growth chamber to the operation chamber by a robot, and the third valve is closed to complete the N-type epitaxial layer growth state.

[0108] In operation S404 , when the growth of the N-type epitaxial layer is completed in the second growth chamber, a robot is used to grab the tray from the operation chamber and transport it to the third growth chamber to grow a P-type epitaxial layer on the N-type epitaxial layer.

[0109] According to an embodiment of the present invention, when the growth of the N-type epitaxial layer is completed in the second growth chamber, a tray is grabbed from the operation chamber by a robot and transported to the third growth chamber to grow a P-type epitaxial layer on the N-type epitaxial layer, including:

[0110] Adjusting the temperature and pressure of the third growth chamber to set values, and introducing a third growth gas from the gas inlet of the third growth chamber; wherein the third growth gas includes a silicon source gas, a carbon source gas, and a P-type dopant source gas;

[0111] When the pressure in the third growth chamber is stable and equal to the pressure in the operation chamber, opening the fourth valve between the third growth chamber and the operation chamber;

[0112] Using a manipulator to grab the tray in the operation chamber and move it to the third growth chamber, then returning the manipulator and closing the fourth valve;

[0113] After the P-type epitaxial layer of the set thickness is grown in the third growth chamber, the fourth valve is opened, the tray is grabbed from the third growth chamber to the operation chamber by a robot, and the fourth valve is closed to complete the growth state of the P-type epitaxial layer.

[0114] In operation S405 , when the growth of the P-type epitaxial layer is completed in the third growth chamber, a robot is used to grab the tray from the operation chamber and transport it to the sampling chamber to complete the preparation of the silicon carbide epitaxial layer.

[0115] According to an embodiment of the present invention, when the P-type epitaxial layer is grown in the third growth chamber, a tray is grabbed from the operating chamber by a robot and transported to the sampling chamber to complete the preparation of the silicon carbide epitaxial layer, including:

[0116] After repeatedly evacuating the operating room and sampling room, flush the operating room and sampling room with inert gas;

[0117] Open the fifth valve between the operating room and the sampling room, use the manipulator to grab the tray from the operating room to the sampling room, close the fifth valve, and complete the sampling state.

[0118] According to an embodiment of the present invention, after the operating chamber interacts with the first growth chamber, the second growth chamber and the third growth chamber, it can independently interact with the transfer chamber; in other words, when the corresponding epitaxial layers are grown simultaneously in the first growth chamber, the second growth chamber and the third growth chamber, a plurality of trays are grabbed by a robot and temporarily stored in the transfer chamber.

[0119] According to an embodiment of the present invention, when the operating chamber and the transfer chamber interact, they also need to be independently and repeatedly vacuumed and then flushed with inert gas to ensure that the pressures in the two chambers are equivalent, and then the sixth valve between the two chambers is opened or closed.

[0120] According to an embodiment of the present invention, there is no need to wait when switching from one epitaxial preparation process to another, so that the epitaxial surface of the wafer will not be damaged, the quality of the epitaxial layer is improved, and the generation of impurities and defects is reduced.

[0121] Figure 5 The flowchart of the method for preparing a silicon carbide epitaxial layer according to another embodiment of the present invention is schematically shown.

[0122] like Figure 5 As shown, the method for preparing a silicon carbide epitaxial layer may further include steps S501 to S507.

[0123] In operation S501, a tray loaded with substrate wafers is transported from a sample preparation room to an operation room using a robot;

[0124] In operation S502, a tray is grabbed from an operating chamber by a robot arm and transported to a first growth chamber to grow a buffer layer on the substrate wafer;

[0125] In operation S503, when the buffer layer growth is completed in the first growth chamber, a tray is grabbed from the operation chamber by a robot and transported to the second growth chamber to grow a first N-type epitaxial layer on the buffer layer;

[0126] In operation S504, when the growth of the first N-type epitaxial layer is completed in the second growth chamber, a tray is grabbed from the operation chamber by a robot and transported to a third growth chamber to grow a first P-type epitaxial layer on the N-type epitaxial layer.

[0127] In operation S505, when the growth of the first P-type epitaxial layer is completed in the third growth chamber, a tray is grabbed from the operation chamber by a robot and transported to the second growth chamber to grow a second N-type epitaxial layer on the first P-type epitaxial layer.

[0128] In operation S506, when the second N-type epitaxial layer is grown in the second growth chamber, a robot is used to grab the tray from the operation chamber and transport it to the third growth chamber to grow a second P-type epitaxial layer on the second N-type epitaxial layer.

[0129] In operation S507 , steps S505 to S506 are repeated multiple times according to the doping conditions of the silicon carbide epitaxial layer.

[0130] According to an embodiment of the present invention, the doping concentrations of the first N-type epitaxial layer, the second N-type epitaxial layer... and the m-th N-type epitaxial layer are different; the doping concentrations of the first P epitaxial layer, the second P epitaxial layer... and the m-th P epitaxial layer are different, thereby preparing a complex epitaxial layer structure with multiple dopings.

[0131] According to an embodiment of the present invention, the detailed preparation process of each step corresponding to this embodiment is the same as that of the first embodiment, and the reaction conditions are adaptively adjusted according to actual doping requirements.

[0132] According to an embodiment of the present invention, there is no need to wait when switching from one epitaxial preparation process to another, so that the epitaxial surface of the wafer will not be damaged, the quality of the epitaxial layer is improved, and the generation of impurities and defects is reduced.

[0133] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A chemical vapor deposition apparatus comprising: A sample preparation room, adapted to provide space for placing trays loaded with substrate wafers; Operating room, including: A manipulator, comprising an elastic cord box, an elastic cord storage wheel, a motor and a movable finger plate, adapted to automatically grab the tray in the sample preparation room and transport it to the corresponding reaction chamber; The elastic rope box is suitable for placing elastic ropes, wherein the material of the manipulator is one of graphite and silicon carbide ceramics, and the elastic rope is a carbon rope, both of which can withstand high temperatures up to 1650°C; The movable finger plate is provided with multiple groups of movable fingers, wherein two adjacent groups of movable fingers form a 90-degree angle, thereby achieving a stable grasping of the tray loaded with wafers; An air trap, comprising an upper portion and a lower portion, adapted to exhaust the gas entering the operating chamber; the upper portion comprises air inlet holes and a first isolation wall laid throughout the entire surface; wherein the air inlet holes are evenly separated by the first isolation wall; The lower portion includes an air trap, a second isolation wall, and an air return hole; wherein the air trap is configured in an annular shape, and a plurality of the air return holes are provided between two adjacent second isolation walls; The reaction chamber comprises: The first growth chamber is adapted to provide a reaction space for growing a buffer layer; The second growth chamber is suitable for providing a reaction space for growing an N-type epitaxial layer; A third growth chamber, adapted to provide a reaction space for growing a P-type epitaxial layer; and a transfer chamber, adapted to provide a temporary storage space for the plurality of trays when corresponding epitaxial layers are grown simultaneously in the first growth chamber, the second growth chamber, and the third growth chamber; A sampling chamber suitable for placing trays loaded with wafers after reaction; The operation chamber is arranged at the center of the chemical vapor deposition equipment, and the sample preparation chamber, the reaction chamber and the sampling chamber are arranged on the same circle centered on the operation chamber; the operation chamber is connected to other chambers via valves.

2. The device according to claim 1, wherein The sample preparation chamber, the reaction chamber, and the sampling chamber are configured as vacuum chambers; The plurality of vacuum chambers are respectively provided with independent gas inlets and gas outlets; The plurality of gas outlets are connected to stainless steel gas pipes and then connected in parallel, and the reaction residual gas is pumped to the tail gas tower through a vacuum pump.

3. The device according to claim 1, wherein The robot has the function of moving along three directions: X axis, Y axis and Z axis.

4. The device according to claim 3, wherein Driven by the motor, the elastic rope storage wheel tightens the elastic rope so that the movable finger drives the spring to move toward the axis, thereby grabbing the tray loaded with wafers; after the motor is removed, the spring contracts, driving the movable finger to move away from the axis, thereby releasing the tray loaded with wafers.

5. The device according to claim 2, wherein The air inlet holes provided on the entire surface are suitable for providing an inlet for introducing inert gas into the operating chamber; The first isolation wall is arranged to connect with the outer wall of each vacuum chamber and is suitable for blocking the inert gas entering the gas inlet hole so that the inert gas moves vertically downward; The gas trap is provided at the bottom of the operating chamber and is adapted to collect the reaction residual gas entering the operating chamber from the plurality of vacuum chambers; The second isolation wall is provided at a position corresponding to the first isolation wall and is suitable for isolating the reaction residual gas entering the operation chamber from the plurality of vacuum chambers; The gas return hole is arranged in the gas trap groove and is configured to be connected to the vacuum pump, thereby pumping the reaction residual gas entering the operating chamber into the tail gas tower.

6. A method for preparing a silicon carbide epitaxial layer, applied to the apparatus according to any one of claims 1 to 5, comprising: Place the tray loaded with substrate wafers in the corresponding position in the sample preparation room. After repeated vacuuming, flush the sample preparation room with inert gas. Use a robot to grab the tray in the sample preparation room and bring it to the operation room to complete the state of waiting for sample loading. Using a robot to grab the tray from the operating chamber and transport it to the first growth chamber to grow a buffer layer on the substrate wafer; When the buffer layer is grown in the first growth chamber, the manipulator grabs the tray from the operation chamber and transports it to the second growth chamber to grow an N-type epitaxial layer on the buffer layer; When the growth of the N-type epitaxial layer is completed in the second growth chamber, the manipulator grabs the tray from the operation chamber and transports it to a third growth chamber to grow a P-type epitaxial layer on the N-type epitaxial layer; When the P-type epitaxial layer is grown in the third growth chamber, the operation chamber and the sampling chamber are repeatedly evacuated, and then flushed with inert gas. The tray is then taken from the operation chamber by a manipulator and transported to the sampling chamber, thereby completing the preparation of the silicon carbide epitaxial layer and completing the sampling state. When the corresponding epitaxial layers are grown simultaneously in the first growth chamber, the second growth chamber, and the third growth chamber, the robot arm is used to grab a plurality of the trays and temporarily store them in the transfer chamber; According to the doping conditions of the silicon carbide epitaxial layer, the tray on which the P-type epitaxial layer has been grown can be retrieved by a robot to the second growth chamber before the sample-out state is completed to achieve the growth of the second N-type epitaxial layer.

7. The method according to claim 6, wherein: Grabbing the tray from the operating chamber using a robot and transporting it to a first growth chamber to grow a buffer layer on the substrate wafer includes: Adjusting the temperature and pressure of the first growth chamber to set values, and introducing a first growth gas from a gas inlet of the first growth chamber; wherein the first growth gas includes a silicon source gas, a carbon source gas, and a buffer source gas; When the pressure in the first growth chamber is stable and is the same as the pressure in the operation chamber, opening the second valve between the first growth chamber and the operation chamber; Using the manipulator to grab the tray in the operation chamber and move it to the first growth chamber, then retracting the manipulator and closing the second valve; After the buffer layer of the set thickness is grown in the first growth chamber, the second valve is opened, the tray is grabbed from the first growth chamber to the operation chamber by the robot, and the second valve is closed.

8. The method according to claim 6, wherein When the buffer layer is grown in the first growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a second growth chamber to grow an N-type epitaxial layer on the buffer layer, comprising: Adjusting the temperature and pressure of the second growth chamber to set values, and introducing a second growth gas from the gas inlet of the second growth chamber; wherein the second growth gas includes a silicon source gas, a carbon source gas, and an N-type dopant source gas; When the pressure in the second growth chamber is stable and is the same as the pressure in the operation chamber, opening a third valve between the second growth chamber and the operation chamber; Using the manipulator to grab the tray in the operation chamber and move it to the second growth chamber, then retracting the manipulator and closing the third valve; After the N-type epitaxial layer of a set thickness is grown in the second growth chamber, the third valve is opened, the tray is grabbed from the second growth chamber to the operation chamber by the robot, and the third valve is closed.

9. The method according to claim 6, wherein When the growth of the N-type epitaxial layer is completed in the second growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a third growth chamber to grow a P-type epitaxial layer on the N-type epitaxial layer, comprising: Adjusting the temperature and pressure of the third growth chamber to set values, and introducing a third growth gas from the gas inlet of the third growth chamber; wherein the third growth gas includes a silicon source gas, a carbon source gas, and a P-type dopant source gas; When the pressure of the third growth chamber is stable and is the same as the pressure of the operation chamber, opening a fourth valve between the third growth chamber and the operation chamber; Using the manipulator to grab the tray in the operation chamber and move it to the third growth chamber, then retracting the manipulator and closing the fourth valve; After the P-type epitaxial layer of a set thickness is grown in the third growth chamber, the fourth valve is opened, the tray is grabbed from the third growth chamber to the operation chamber by the robot, and the fourth valve is closed.

10. The method according to claim 6, further comprising: S1: transport the tray loaded with substrate wafers from the sample preparation room to the operation room; S2: using a robot to grab the tray from the operating chamber and transport it to the first growth chamber to grow a buffer layer on the substrate wafer; S3: When the buffer layer is grown in the first growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a second growth chamber to grow a first N-type epitaxial layer on the buffer layer. S4: When the growth of the first N-type epitaxial layer is completed in the second growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a third growth chamber to grow a first P-type epitaxial layer on the N-type epitaxial layer. S5: When the growth of the first P-type epitaxial layer is completed in the third growth chamber, the tray is grabbed from the operation chamber by a robot and transported to the second growth chamber to grow a second N-type epitaxial layer on the first P-type epitaxial layer; S6: When the second N-type epitaxial layer is grown in the second growth chamber, the tray is grabbed from the operation chamber by a robot and transported to a third growth chamber to grow a second P-type epitaxial layer on the second N-type epitaxial layer. S7: Repeat S5 to S6 multiple times according to the doping conditions of the silicon carbide epitaxial layer.

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