GaN vertical device based on conductive type SiC substrate and growth method thereof

Abstract

The application relates to a GaN vertical device based on a conductive SiC substrate and a growth method thereof, and belongs to the technical field of semiconductor vertical devices. In a MOCVD system, a SiN interface layer and an N-type AlGaN doped connection layer structure are adopted to perform epitaxial growth on a SiC substrate, the SIN interface layer and the N-type AlGaN doped connection layer are adopted to well solve the conductive doping problem of the substrate and the growth layer, then an N-type GaN thick film is prepared on the SiC substrate, a conductive material is grown, and finally, the vertical device is etched and prepared, and the vertical structure device has very good voltage resistance performance.

Description

Technical Field

[0001] This invention relates to a GaN vertical device based on a conductive SiC substrate and its growth method, belonging to the field of semiconductor vertical device technology. Background Technology

[0002] With the continuous advancement of science and technology, the design and manufacturing technology of semiconductor devices has developed significantly. Among them, vertical devices, as a new type of semiconductor device, have many advantages, such as high breakdown voltage, high current density, and good thermal stability, and are widely used in power electronics, new energy, automotive electronics, communications and other fields.

[0003] In vertical devices, current can be conducted through conductive channels in the vertical direction, allowing for greater current conduction capacity without increasing device area. Furthermore, the structural design of vertical devices allows for better optimization of device performance, such as improving breakdown voltage and thermal stability by optimizing the thickness and doping concentration of the drift region.

[0004] Advanced semiconductor process technologies, such as ion implantation, thin film growth, and etching, are typically used in the manufacture of vertical devices. These technologies enable the production of vertical devices with high precision, high consistency, and high reliability.

[0005] In the field of power electronics, vertical devices can be used in circuits such as switching power supplies, frequency converters, and rectifiers to achieve efficient and reliable energy conversion. In the field of new energy, vertical devices can be used in devices such as solar cells, wind power generation, and energy storage systems to achieve energy storage and conversion. In the field of automotive electronics, vertical devices can be used in devices such as motor control, power management, and safety systems to achieve efficient and reliable electronic control. In the field of communications, vertical devices can be used in devices such as high-frequency electronic devices and radio frequency power amplifiers to achieve high-speed, high-power signal transmission and processing.

[0006] Horizontal structure devices suffer from current congestion, which can lead to performance degradation over long periods of operation. In contrast, vertical structure devices offer advantages such as uniform current distribution, low heat generation, simple manufacturing process, and large active area.

[0007] The SiC substrate has a relatively small lattice mismatch with GaN, exhibiting excellent electrical and thermal conductivity. Furthermore, it shares the same cleavage plane as GaN, making it an ideal heteroepitaxial substrate. However, the SiC substrate surface is covered with an oxide film, and the 3.4% lattice mismatch and significant thermal mismatch between GaN and the SiC substrate introduce numerous dislocation defects and cracks into the GaN epitaxial film, affecting the quality of the GaN thin film.

[0008] AlN buffer layers are considered a good solution. AlN has good wettability with SiC, avoiding direct contact between Ga and the SiC substrate, effectively suppressing the remelting effect, and the lattice mismatch between AlN and GaN is only 1%. However, AlN is difficult to dope, which is not conducive to the fabrication of vertical structures and makes it difficult to take advantage of the good conductivity of the SiC substrate.

[0009] In summary, vertical devices have a very broad technological background and broad application and market prospects. Summary of the Invention

[0010] To address the shortcomings of existing technologies, this invention provides a method for growing and fabricating vertical devices on conductive SiC substrates. This invention innovatively employs a SiN interface layer and an N-type AlGaN doped bonding layer structure for epitaxial growth on SiC substrates within an MOCVD system. The SiN interface layer and the N-type AlGaN doped bonding layer address the conductivity doping issues between the substrate and the growth layer. Then, an N-type GaN thick film is prepared on the SiC substrate to grow conductive materials. Finally, vertical devices are fabricated through etching, resulting in devices with excellent voltage withstand performance.

[0011] The technical solution of the present invention is as follows: A GaN vertical device based on a conductive SiC substrate includes, from bottom to top, an N-type SiC substrate, a SIN interface layer, an N-type AlGaN doped bonding layer, an N-type GaN thick film layer, a GaN channel layer, an AlGaN barrier layer, and an SiO2 layer. A gate is located above the SiO2 layer, and a drain is located below the N-type SiC substrate. A high-resistivity layer and a source are located from bottom to top between the N-type GaN thick film layer and the SiO2 layer on both sides of the GaN vertical device.

[0012] Preferably, the upper surface of the source electrode is higher than the upper surface of the AlGaN barrier layer.

[0013] A method for growing GaN vertical devices based on conductive SiC substrates includes the following steps: (1) Surface treatment of N-type SiC substrate: Heat the MOCVD equipment, set the growth chamber pressure, tray speed and hydrogen, and bake in hydrogen environment; (2) A SIN interface layer, an N-type AlGaN doped bonding layer, an N-type GaN thick film layer, a GaN channel layer, and an AlGaN barrier layer are sequentially grown on an N-type SiC substrate to obtain the epitaxial wafer for the preparation of the vertical device. (3) Clean and treat the surface of the grown epitaxial wafer, and then etch it to remove the GaN channel layer and AlGaN barrier layer grown on both sides. (4) Ion implantation is performed on the N-type GaN thick film in the etched area, and Fe or C ions are implanted to form a GaN high-resistivity layer; (5) Fabricate the source electrode on the GaN high-resistivity layer and deposit the source electrode metal by electron beam evaporation; (6) A SiO2 layer is deposited on the surface of the device with the source electrode fabricated; (7) Fabricate the gate on the SiO2 layer; fabricate the drain on the N-type SiC substrate to obtain the GaN vertical device.

[0014] Preferably, in step (1), the MOCVD equipment is heated to 1200-1250℃, the growth chamber pressure is 100-200 Torr, the tray rotation speed is 800-1200 rpm, and the hydrogen gas is 80-120 liters. The equipment is then baked in a hydrogen environment for 10-20 minutes.

[0015] Preferably, in step (2), the growth of the SIN interface layer is as follows: the MOCVD temperature is raised to 1200℃-1250℃, the growth chamber pressure is 50-200 Torr, the tray rotation speed is 800-1000 rpm, the nitrogen, hydrogen and ammonia are 30-50, 80-120 and 30-50 liters respectively, the time is 30-120 seconds, and SIH4 is introduced at 100-200 sccm.

[0016] Preferably, in step (2), the growth of the N-type ALGAN doped bonding layer is as follows: the MOCVD temperature is raised to 1200℃-1250℃, and then Ga source is introduced into the reaction chamber at 100-200cc, AL source at 100-300cc, growth chamber pressure at 50-200 Torr, tray rotation speed at 800-1200 rpm, nitrogen, hydrogen and ammonia at 30-50, 80-120 and 30-50 liters respectively, for 300-600 seconds, and SIH4 is introduced at 20-100 sccm.

[0017] Preferably, in step (2), the growth of the N-type GaN thick film is as follows: the MOCVD temperature is reduced from 1200℃ to 1100℃, and then 200-500cc of Ga is introduced into the reaction chamber. The growth chamber pressure is 100-200 Torr, the tray rotation speed is 1000-1200 rpm, and the nitrogen, hydrogen, and ammonia gases are 30-50, 80-120, and 30-50 liters, respectively. The growth time is 3600s, and 40-100sccm of SIH4 is introduced to obtain the N-type gallium nitride thick film.

[0018] Preferably, in step (2), the GaN channel layer is grown by introducing a Ga source into the reaction chamber of MOCVD at a flow rate of 100-300, while keeping the growth temperature, tray rotation speed, and nitrogen, hydrogen, and ammonia constant for 200-600 seconds.

[0019] Preferably, in step (2), the growth of the AlGaN barrier layer is as follows: the tray rotation speed and nitrogen, hydrogen and ammonia remain unchanged, the MOCVD temperature is raised to 1200℃, and then AL and Ga sources are introduced with flow rates of 100-200 sccm and 50-600 sccm, respectively, and the growth time is 120-240 seconds.

[0020] Any aspects not detailed in this invention are conventional prior art.

[0021] The beneficial effects of this invention are as follows: Existing SiC devices are difficult to fabricate vertical devices on conductive SiC substrates due to the difficulty in doping the buffer layer. However, this invention allows for direct doping on conductive SiC substrates to fabricate vertical devices, growing a layer that is conductive to the substrate.

[0022] This invention effectively solves the technical problem of growing high-quality GaN thin films on SiC. It adopts a different method for growing the substrate and a different process for fabricating the device. The growth process is simple, easy to implement, and reproducible.

[0023] The GaN epitaxial wafers grown by this invention have low defect density, high crystal quality, and electrical advantages.

[0024] This invention effectively solves the problem that traditional techniques are difficult to use for doping and cannot fabricate GaN vertical structure devices. It can be widely used in the field of semiconductor vertical structure devices and is easy to promote and apply.

[0025] The vertically structured device prepared based on this invention has very good voltage resistance. Attached Figure Description

[0026] Figure 1 Schematic diagram of the epitaxial growth structure of GaN vertical devices; Figure 2 Schematic diagram of vertical device; Figures 3a-3e A schematic diagram of the fabrication steps for vertical components; Schematic diagram: 1. N-type SiC substrate; 2. SIN interface layer; 3. AlGaN doped bonding layer; 4. N-type GaN thick film layer; 5. GaN channel layer; 6. AlGaN barrier layer; 7. GaN high resistivity layer; 8. Source; 9. SiO2 layer; 10. Gate; 11. Drain. Detailed Implementation

[0027] To enable the objectives, features, and effects of the present invention to be more fully realized and more easily understood, the present invention will be further described below in conjunction with embodiments and accompanying drawings.

[0028] The following embodiments are merely preferred technical solutions of the present invention and are not intended to limit the present invention in any way.

[0029] Unless otherwise specified, all raw materials used in the embodiments are conventional raw materials and are commercially available; all methods used are existing methods unless otherwise specified.

[0030] Example 1

[0031] like Figure 2 As shown, a GaN vertical device based on a conductive SiC substrate includes, from bottom to top, an N-type SiC substrate 1, a SiN interface layer 2, an N-type AlGaN doped bonding layer 3, an N-type GaN thick film layer 4, a GaN channel layer 5, an AlGaN barrier layer 6, and an SiO2 layer 9. A gate 10 is provided above the SiO2 layer, a drain 11 is provided below the N-type SiC substrate, and a high-resistivity layer 7 and a source 8 are provided from bottom to top between the N-type GaN thick film layer and the SiO2 layer on both sides of the GaN vertical device.

[0032] Example 2

[0033] A method for growing GaN vertical devices based on conductive SiC substrates includes the following steps: (1) For the surface treatment of N-type SiC substrate, first heat the MOCVD equipment to 1250℃, the growth chamber pressure to 200 Torr, the tray rotation speed to 1200 rpm, and 120 liters of hydrogen, and bake in the hydrogen environment for 12 minutes. (2) A SIN interface layer, an N-type AlGaN doped bonding layer, an N-type GaN thick film layer, a GaN channel layer, and an AlGaN barrier layer are sequentially grown on an N-type SiC substrate to obtain the epitaxial wafer for preparing the vertical device, as shown below. Figure 1 ; Growth of the SIN interface layer: The MOCVD temperature was raised to 1250℃, the growth chamber pressure was 100 Torr, the tray rotation speed was 1000 rpm, the nitrogen, hydrogen and ammonia were 30-50, 80-120 and 30-50 liters respectively, the time was 60 seconds, and 100 sccm of SIH4 was introduced. Growth of N-type ALGaN doped bonding layer: The MOCVD temperature was raised to 1230℃, the tray rotation speed was 1200 rpm, and the nitrogen, hydrogen and ammonia were 30-50, 80-120 and 30-50 liters respectively. Then, AL and Ga sources were introduced at flow rates of 100 sccm and 200 sccm respectively. The growth time was 300 seconds, and SIH4 was introduced at 20 sccm. Growth of N-type GaN thick films: The MOCVD temperature is reduced from 1200℃ to 1100℃, and then 200-500cc of Ga is introduced into the reaction chamber. The growth chamber pressure is 200 Torr, the tray rotation speed is 1200 rpm, and the nitrogen, hydrogen, and ammonia gases are 30-50, 80-120, and 30-50 liters, respectively. The growth time is 3600s, and 40-100sccm of SIH4 is introduced to obtain N-type gallium nitride thick films. Growth of GaN channel layers: Ga source was introduced into the reaction chamber of MOCVD at a flow rate of 200 Sccm, while the growth temperature, tray rotation speed, and nitrogen, hydrogen, and ammonia were kept constant for 300 seconds. Growth of the ALGAN barrier layer: The tray rotation speed and nitrogen-hydrogen-ammonia were kept constant, the MOCVD temperature was raised to 1200℃, and then AL and Ga sources were introduced at flow rates of 100 sccm and 600 sccm, respectively, for a growth time of 180 seconds. (3) such as Figure 3a The grown epitaxial wafer is cleaned and treated, and then etched to remove the GaN channel layer 5 and AlGaN barrier layer 6 grown on both sides. (4) such as Figure 3b Ion implantation is performed in the etched area to form a GaN high-resistivity layer 7 using Fe or C ion implantation. (5) such as Figure 3c The source electrode is fabricated on a GaN high-resistivity layer, and the source electrode metal is deposited by electron beam evaporation. (6) For example Figure 3d A layer of SiO2 is deposited on the surface of the fabricated source electrode. (7) For example Figure 3e Gate 10 is fabricated on top of the SiO2 layer; drain 11 is fabricated on an N-type SiC substrate 1, resulting in the following... Figure 2 The GaN vertical device shown.

[0034] Any aspects not detailed in this invention are conventional prior art.

[0035] For those skilled in the art, various modifications and variations can be made to this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0036] This invention effectively solves the problem of traditional techniques being difficult to use for doping and fabricating GaN vertical structure devices. It can be widely applied in the field of semiconductor vertical structure devices and is easy to promote and apply. The growth process is simple, easy to perform, and reproducible.

[0037] The vertically structured device prepared based on this invention has very good voltage resistance.

Claims

1. A GaN vertical device based on a conductive SiC substrate, characterized in that, From bottom to top, it includes an N-type SiC substrate, a SiN interface layer, an N-type AlGaN doped bonding layer, an N-type GaN thick film layer, a GaN channel layer, an AlGaN barrier layer, and a SiO2 layer. A gate is located above the SiO2 layer, and a drain is located below the N-type SiC substrate. A high-resistivity layer and a source are located from bottom to top between the N-type GaN thick film layer and the SiO2 layer on both sides of the GaN vertical device.

2. The GaN vertical device based on a conductive SiC substrate according to claim 1, characterized in that, The source surface is higher than the AlGaN barrier layer surface.

3. A method for fabricating a GaN vertical device based on a conductive SiC substrate as described in claim 1, characterized in that, The steps include the following: (1) Surface treatment of N-type SiC substrate: Heat the MOCVD equipment, set the growth chamber pressure, tray speed and hydrogen, and bake in hydrogen environment; (2) On an N-type SiC substrate, a SiN interface layer, an N-type AlGaN doped bonding layer, an N-type GaN thick film layer, a GaN channel layer, and an AlGaN barrier layer are grown sequentially to obtain an epitaxial wafer for fabricating vertical devices. (3) Clean and treat the surface of the grown epitaxial wafer, and then etch it to remove the GaN channel layer and AlGaN barrier layer grown on both sides. (4) Ion implantation is performed on the N-type GaN thick film in the etched area, and Fe or C ions are implanted to form a GaN high-resistivity layer; (5) Fabricate the source electrode on the GaN high-resistivity layer and deposit the source electrode metal by electron beam evaporation; (6) A SiO2 layer is deposited on the surface of the device with the source electrode fabricated; (7) Fabricate the gate on the SiO2 layer; fabricate the drain on the N-type SiC substrate to obtain the GaN vertical device.

4. The method for growing GaN vertical devices based on conductive SiC substrates according to claim 3, characterized in that, In step (1), the MOCVD equipment is heated to 1200-1250℃, the growth chamber pressure is 100-200 Torr, and it is baked in a hydrogen environment for 10-20 minutes.

5. The method for growing GaN vertical devices based on conductive SiC substrates according to claim 3, characterized in that, In step (2), the SiN interface layer is grown by raising the MOCVD temperature to 1200℃-1250℃, the growth chamber pressure to 50-200 Torr, and introducing nitrogen, hydrogen, and ammonia gas. The growth time is 30-120 seconds, and SiH4 is introduced at 100-200 sccm.

6. The method for growing GaN vertical devices based on conductive SiC substrates according to claim 3, characterized in that, In step (2), the growth of the N-type AlGaN doped bonding layer is as follows: the MOCVD temperature is raised to 1200℃-1250℃, and then Ga source and Al source are introduced into the reaction chamber. The growth chamber pressure is 50-200 Torr, and nitrogen, hydrogen and ammonia are introduced. The growth time is 300-600 seconds, and SiH4 is introduced at 20-100 sccm.

7. The method for growing GaN vertical devices based on conductive SiC substrates according to claim 3, characterized in that, In step (2), the growth of the N-type GaN thick film is carried out by reducing the temperature of MOCVD from 1200℃ to 1100℃, then introducing a Ga source into the reaction chamber, the pressure in the growth chamber is 100-200 Torr, and nitrogen, hydrogen and ammonia are introduced. The growth time is 3600s, and SiH4 is introduced at 40-100 sccm to obtain the N-type GaN thick film.

8. The method for growing GaN vertical devices based on conductive SiC substrates according to claim 3, characterized in that, In step (2), GaN channel layer growth: Ga source is introduced into the reaction chamber of MOCVD, and the growth time is 200-600 seconds.

9. The method for growing GaN vertical devices based on conductive SiC substrates according to claim 3, characterized in that, In step (2), the growth of the AlGaN barrier layer is carried out by raising the MOCVD temperature to 1200℃ and then introducing Al and Ga sources with flow rates of 100-200 sccm and 50-600 sccm, respectively, and the growth time is 120-240 seconds.

Images