A resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrate pieces

Abstract

This utility model relates to the field of semiconductor material preparation technology, specifically disclosing a resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates. The furnace includes a furnace body with a heat insulation layer fixedly connected to its inner wall. The heat insulation layer consists of a graphite felt layer, a carbon fiber felt layer, and an alumina ceramic layer, arranged sequentially from the inside out. Sealing flanges are detachably connected to the upper and lower ends of the furnace body via bolts. The heating mechanism includes a multi-layered annular heating structure axially distributed along the inner wall of the furnace. Axial zone temperature control of the multi-layered annular resistance heating element, edge compensation of the auxiliary heating ring, and base rotation reduce the temperature difference on the substrate surface, resulting in a more uniform epitaxial layer thickness. The combination of a spiral guide tube and a porous flow equalizer reduces gas flow velocity deviation. Simultaneously, resistance heating is highly efficient and more energy-saving than induction heating, and eliminates the need for a high-frequency power supply and electromagnetic shielding structure, reducing manufacturing costs. The heat insulation layer also reduces heat loss.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor material preparation technology, and specifically discloses a resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates. Background Technology

[0002] The semiconductor industry, as the foundation of the modern electronic information industry, is a crucial sector supporting the high-quality development of the national economy. Third-generation semiconductors refer to emerging semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) with wide bandgap characteristics (Eg > 2.3 eV). Silicon carbide is currently the most mature third-generation semiconductor material. Silicon carbide devices offer advantages such as small size, high power, high frequency, low energy consumption, low loss, and high voltage resistance. Current major applications include various power supplies and servers, photovoltaic inverters, wind power inverters, on-board chargers and motor drive systems for new energy vehicles, DC charging piles, variable frequency air conditioners, rail transportation, and military applications.

[0003] Silicon carbide epitaxial wafers are a key material for manufacturing high-power, high-frequency devices, and their quality directly affects device performance. Currently, chemical vapor deposition (CVD) epitaxial furnaces mostly employ induction heating, using high-frequency coils to heat the graphite substrate. However, induction heating has the following drawbacks:

[0004] Temperature gradients are easily formed between the edges and the center of the graphite substrate, resulting in uneven thickness and doping concentration of the epitaxial layer.

[0005] Induction heating requires high-frequency power supplies and complex cooling systems, resulting in high energy consumption and operating costs.

[0006] It requires electromagnetic shielding and coil cooling devices, has a complex structure, and is difficult to maintain.

[0007] Although resistance heating technology has been applied in some fields, it has not yet effectively replaced induction heating in silicon carbide epitaxial growth due to problems such as unreasonable thermal field design and uneven gas distribution. Therefore, there is an urgent need for an epitaxial furnace with simple structure, good temperature uniformity and low energy consumption. Utility Model Content

[0008] This invention proposes a resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates. By using a multi-layer annular resistance heating body with axial zone temperature control, auxiliary heating ring edge compensation, and base rotation, the temperature difference on the substrate surface is reduced, the epitaxial layer thickness is more uniform, the resistance heating efficiency is high, and the high-frequency power supply and electromagnetic shielding structure are eliminated, thus reducing manufacturing costs and reducing heat loss through the heat insulation layer.

[0009] This invention is implemented as follows: a resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate, comprising:

[0010] The furnace body has an insulation layer fixedly connected to its inner wall. The insulation layer consists of a graphite felt layer, a carbon fiber felt layer, and an alumina ceramic layer from the inside out. Both the upper and lower ends of the furnace body are detachably connected to sealing flange plates by bolts.

[0011] The heating mechanism includes a multi-layered annular heating structure distributed axially along the inner wall of the furnace. The annular heating structure includes a high-temperature resistant ceramic support fixedly connected to the inner wall of the furnace. Multiple arc-shaped resistance heating elements are embedded inside the high-temperature resistant ceramic support.

[0012] A gas supply mechanism includes an air inlet disposed on the outer wall of the upper sealing flange plate. The bottom of the air inlet is connected to a spiral guide tube located inside the furnace body. A porous flow equalizing plate is disposed directly below the spiral guide tube. The porous flow equalizing plate is fixedly connected to the inner wall of the furnace body by a ceramic column.

[0013] A substrate support device includes a graphite base disposed below the interior of a furnace body, a thermocouple embedded in the bottom of the graphite base, a base disposed below the graphite base, and multiple silicon carbide pillars fixedly connected between the graphite base and the base.

[0014] As a preferred embodiment of the resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates according to this invention, the heating mechanism further includes an auxiliary heating ring embedded in the upper end face of the graphite base.

[0015] As a preferred embodiment of the resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates according to this utility model, the gas supply mechanism further includes an exhaust port disposed below the outer wall of the furnace body, the outer wall of the exhaust port being connected to an exhaust pipe, the outer wall of the exhaust pipe being provided with a vacuum pump, and the interior of the exhaust pipe being provided with a pressure sensor.

[0016] As a preferred embodiment of the resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates according to this invention, a motor is installed below the furnace body, and the output end of the motor is fixedly connected to the base through a magnetohydrodynamic sealing shaft.

[0017] As a preferred embodiment of the resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates according to this invention, all of the aforementioned annular heating structures are electrically connected to an external thyristor power supply via molybdenum wires.

[0018] As a preferred embodiment of the present invention, a resistance heating epitaxial furnace for growing epitaxial layers on silicon carbide substrates, the spiral guide cylinder has an overall conical structure and a spiral guide plate is fixedly connected to its inner wall.

[0019] As a preferred embodiment of the present invention, a resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate is wherein the surface of the resistance heating body is coated with a silicon carbide coating with a coating thickness of 10-20 μm.

[0020] The beneficial effects of this utility model are:

[0021] This invention reduces the temperature difference on the substrate surface and makes the epitaxial layer thickness more uniform by using a multi-layer annular resistance heating element with axial zone temperature control, auxiliary heating ring edge compensation, and base rotation. The combination of a spiral guide tube and a porous flow equalizer reduces gas flow velocity deviation, while the resistance heating efficiency is high and the high-frequency power supply and electromagnetic shielding structure are eliminated, reducing manufacturing costs. The heat insulation layer reduces heat loss. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0023] Figure 1 This is a front sectional view of the overall structure of this utility model;

[0024] Figure 2 This is a three-dimensional structural diagram of the high-temperature resistant ceramic support of this utility model;

[0025] Figure 3 This is a cross-sectional structural diagram of the insulation layer of this utility model;

[0026] Figure 4 This is a bottom view of the spiral guide tube structure of this utility model;

[0027] Figure 5 This is a three-dimensional structural diagram of the porous flow equalizer of this utility model.

[0028] The markings in the diagram are as follows: 1. Furnace body; 2. Insulation layer; 3. Graphite felt layer; 4. Carbon fiber felt layer; 5. Alumina ceramic layer; 6. High-temperature resistant ceramic support; 7. Resistance heating element; 8. Air inlet; 9. Spiral guide tube; 10. Porous flow equalizer; 11. Ceramic column; 12. Graphite base; 13. Thermocouple; 14. Base; 15. Silicon carbide support; 16. Auxiliary heating ring; 17. Magnetohydrodynamic sealing shaft; 18. Motor; 19. Exhaust port; 20. Exhaust pipe; 21. Vacuum pump; 22. Pressure sensor; 23. Sealing flange plate. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments to aid in understanding its content. Unless otherwise specified, the methods used in this invention are conventional methods; the raw materials and apparatus used, unless otherwise specified, are conventional commercially available products.

[0030] Please see Figure 1-5 A resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate, comprising:

[0031] Furnace body 1, the inner wall of furnace body 1 is fixedly connected with heat insulation layer 2, the heat insulation layer 2 consists of graphite felt layer 3, carbon fiber felt layer 4 and alumina ceramic layer 5 from the inside to the outside, and sealing flange plate 23 is detachably connected to the upper and lower ends of furnace body 1 by bolts.

[0032] The heating mechanism includes a multi-layer annular heating structure distributed axially along the inner wall of the furnace body 1. The annular heating structure includes a high-temperature resistant ceramic support 6 fixedly connected to the inner wall of the furnace body 1. Multiple arc-shaped resistance heating elements 7 are embedded inside the high-temperature resistant ceramic support 6.

[0033] The gas supply mechanism includes an air inlet 8 disposed on the outer wall of the upper sealing flange plate 23. The bottom of the air inlet 8 is connected to a spiral guide cylinder 9 located inside the furnace body 1. A porous flow equalizing plate 10 is disposed directly below the spiral guide cylinder 9. The porous flow equalizing plate 10 is fixedly connected to the inner wall of the furnace body 1 by a ceramic column 11.

[0034] The substrate support device includes a graphite base 12 disposed inside the furnace body 1 at the bottom, a thermocouple 13 embedded in the bottom of the graphite base 12, a base 14 disposed below the graphite base 12, and a plurality of silicon carbide pillars 15 fixedly connected between the graphite base 12 and the base 14.

[0035] In this embodiment: the arc-shaped resistance heating element 7 distributed axially along the inner wall of the furnace can independently control the axial and radial temperature distribution of the furnace cavity. The auxiliary heating ring 16 is embedded in the edge of the graphite base 12 to compensate for the heat loss of the outer edge of the base. Combined with the heat insulation effect of the silicon carbide support 15, the uniformity of the substrate surface temperature is ensured. The motor 18 drives the graphite base 12 to rotate at 1-5 rpm to further reduce the local temperature gradient.

[0036] After the reactant gas enters from the top inlet 8, it forms a rotating airflow through the conical spiral guide tube 9, and then evenly covers the substrate surface through the flow equalization effect of the porous flow equalization plate 10, avoiding dead zones in the airflow. After the gas reacts on the substrate, it is discharged from the exhaust port 19 at the bottom of the furnace, forming a vertical flow field of "top inlet - bottom exhaust" to reduce turbulence interference.

[0037] Thermocouple 13, embedded at the bottom of graphite base 12, monitors the temperature in real time and adjusts the power of resistance heating element 7 and auxiliary heating ring 16 through PID algorithm to improve temperature control accuracy.

[0038] The graphite felt layer 3, carbon fiber felt layer 4, and alumina ceramic layer 5 have good thermal insulation properties, which reduces heat loss from the furnace cavity.

[0039] The upper and lower sealing flanges 23 are designed to be detachable, which facilitates substrate loading and equipment maintenance.

[0040] As a technical optimization of this utility model, the heating mechanism also includes an auxiliary heating ring 16 embedded in the upper surface of the graphite base 12.

[0041] In this embodiment, the auxiliary heating ring 16 is embedded in the edge of the graphite base 12 to compensate for heat loss at the outer edge of the base. Combined with the heat insulation effect of the silicon carbide pillar 15, it ensures the uniformity of the substrate surface temperature.

[0042] As a technical optimization of this utility model, the gas supply mechanism also includes an exhaust port 19 located below the outer wall of the furnace body 1. The outer wall of the exhaust port 19 is connected to an exhaust pipe 20. A vacuum pump 21 is installed on the outer wall of the exhaust pipe 20, and a pressure sensor 22 is installed inside the exhaust pipe 20.

[0043] In this embodiment: after the reaction gas enters from the top air inlet 8, it forms a rotating airflow through the conical spiral guide tube 9, and then evenly covers the substrate surface through the flow equalization effect of the porous flow equalization plate 10. After the gas reacts on the substrate, it is discharged from the exhaust port 19 at the bottom of the furnace body, forming a vertical flow field of "upper air inlet - lower exhaust outlet" to reduce turbulence interference. The vacuum pump 21 facilitates the evacuation of the furnace body 1, and the pressure sensor 22 detects the internal pressure of the furnace body 1 in real time.

[0044] As a technical optimization of this utility model, a motor 18 is installed below the furnace body 1, and the output end of the motor 18 is fixedly connected to the base 14 through a magnetic fluid sealing shaft 17.

[0045] In this embodiment, the output end of the motor 18 is fixedly connected to the base 14 through the magnetic fluid sealing shaft 17, which facilitates driving the graphite base 12 to rotate.

[0046] As a technical optimization of this utility model, multiple annular heating structures are electrically connected to an external thyristor power supply via molybdenum wires.

[0047] In this embodiment, multiple annular heating structures are electrically connected to an external thyristor power supply via molybdenum wires to achieve independent temperature control.

[0048] As a technical optimization of this utility model, the spiral guide tube 9 has an overall conical structure and a spiral guide plate is fixedly connected to its inner wall.

[0049] In this embodiment: the spiral guide tube 9 has an overall conical structure and a spiral guide plate is fixedly connected to the inner wall to facilitate the formation of spiral airflow.

[0050] As a technical optimization of this utility model, the surface of the resistance heating element 7 is coated with a silicon carbide coating with a coating thickness of 10-20μm.

[0051] In this embodiment, the surface of the resistance heating element 7 is coated with a silicon carbide coating with a thickness of 10-20 μm, which effectively improves the corrosion resistance and high temperature resistance of the surface of the resistance heating element 7 and extends its service life.

[0052] The working principle and usage process of this utility model are as follows: When the epitaxial furnace is working, the multi-layer annular resistance heating element 7 is distributed along the axial direction of the furnace body 1, and a gradient thermal field is formed in the furnace cavity through independent temperature control; after the reaction gas enters from the top air inlet 8, it is transformed into a rotating airflow through the conical spiral structure of the spiral guide tube 9, and then diffused into a uniform laminar flow through the porous flow equalization plate 10; the gas flows vertically over the surface of the rotating graphite base 12, and a chemical vapor deposition reaction occurs at high temperature to generate a silicon carbide epitaxial layer; the thermocouple 13 embedded at the bottom of the base monitors the temperature in real time, and the power of each layer of heating element and auxiliary heating ring 16 is dynamically adjusted through the temperature control system; the exhaust gas is discharged from the bottom exhaust port 19 through the vacuum pump 21, the composite heat insulation layer 2 reduces heat loss, and the magnetic fluid sealing shaft 17 drives the base to rotate to eliminate local temperature and airflow unevenness.

[0053] In the description of this utility model, it should be understood that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inner", "outer", "back", "middle", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0054] However, the above description is only a specific embodiment of this utility model and should not be construed as limiting the scope of implementation of this utility model. Therefore, any substitution of equivalent components or equivalent changes and modifications made in accordance with the scope of protection of this utility model should still fall within the scope of the claims of this utility model.

Claims

1. A resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate, characterized in that: include: The furnace body (1) has a heat insulation layer (2) fixedly connected to its inner wall. The heat insulation layer (2) consists of a graphite felt layer (3), a carbon fiber felt layer (4), and an alumina ceramic layer (5) from the inside to the outside. Both the upper and lower ends of the furnace body (1) are detachably connected to a sealing flange plate (23) by bolts. The heating mechanism includes a multi-layer annular heating structure distributed axially along the inner wall of the furnace body (1). The annular heating structure includes a high-temperature resistant ceramic support (6) fixedly connected to the inner wall of the furnace body (1). Multiple arc-shaped resistance heating elements (7) are embedded inside the high-temperature resistant ceramic support (6). The gas supply mechanism includes an air inlet (8) disposed on the outer wall of the upper sealing flange plate (23), the bottom of the air inlet (8) is connected to a spiral guide cylinder (9) located inside the furnace body (1), a porous flow equalizing plate (10) is disposed directly below the spiral guide cylinder (9), and the porous flow equalizing plate (10) is fixedly connected to the inner wall of the furnace body (1) by a ceramic column (11); The substrate support device includes a graphite base (12) disposed below the interior of the furnace body (1), a thermocouple (13) is embedded in the bottom of the graphite base (12), a base (14) is disposed below the graphite base (12), and a plurality of silicon carbide pillars (15) are fixedly connected between the graphite base (12) and the base (14).

2. The resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate according to claim 1, characterized in that: The heating mechanism also includes an auxiliary heating ring (16) embedded in the upper surface of the graphite base (12).

3. The resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate according to claim 1, characterized in that: The gas supply mechanism also includes an exhaust port (19) located below the outer wall of the furnace body (1). The outer wall of the exhaust port (19) is connected to an exhaust pipe (20). The outer wall of the exhaust pipe (20) is equipped with a vacuum pump (21). The interior of the exhaust pipe (20) is equipped with a pressure sensor (22).

4. The resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate according to claim 1, characterized in that: A motor (18) is installed below the furnace body (1), and the output end of the motor (18) is fixedly connected to the base (14) through a magnetic fluid sealing shaft (17).

5. The resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate according to claim 1, characterized in that: All of the aforementioned annular heating structures are electrically connected to an external thyristor power supply via molybdenum wires.

6. The resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate according to claim 1, characterized in that: The spiral guide tube (9) has an overall conical structure and a spiral guide plate is fixedly connected to its inner wall.

7. The resistance heating epitaxial furnace for growing epitaxial layers on a silicon carbide substrate according to claim 1, characterized in that: The surface of the resistance heating element (7) is coated with a silicon carbide coating with a thickness of 10-20 μm.

Images