Gallium oxide power diode with junction terminal expansion and groove composite terminal structure and preparation method thereof
By introducing junction termination extension and trench composite termination structures into gallium oxide power devices, the problems of electric field spike breakdown and area occupancy under high voltage are solved, achieving high breakdown voltage and high terminal area utilization efficiency, thus improving the application of the device in high voltage scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-03-10
AI Technical Summary
Existing gallium oxide power devices are prone to local electric field spike breakdown under high voltage. Traditional planar junction termination extension structures occupy a large area, and trench structures have limited voltage withstand capability, thus limiting their application potential in high-voltage scenarios.
By employing a junction termination extension and trench composite termination structure, a complementary design is formed by setting trenches in the gallium oxide epitaxial layer and covering the trench sidewalls and bottom with a portion of the p-type semiconductor layer. This extends the charge distribution and forces the electric field to distribute along the trench depth, thus alleviating electric field concentration.
The breakdown voltage was increased, the terminal area was reduced, the electric field distribution was optimized, and premature breakdown of the dielectric layer was avoided, thus enhancing the application potential of gallium oxide power devices in high-voltage scenarios.
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Figure CN121645908A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power semiconductor technology, specifically relating to a gallium oxide power diode with a junction termination extension and trench composite termination structure and its fabrication method. Background Technology
[0002] With breakthroughs in technologies such as AI, 5G communication, and electric vehicles, as well as upgrades in rail transit, new energy power generation, and power transmission systems, the market demand for high-voltage, high-power electronic devices is increasing. Gallium oxide (GaO), a fourth-generation semiconductor material, possesses an ultra-wide bandwidth (4.6-4.9 eV), a high critical breakdown field strength (~8 MV / cm), and a high Baliga figure of merit (>3000), giving it significant advantages in high-voltage, low-loss power devices. However, in practical applications, when power devices are subjected to high voltage, curvature effects can lead to local electric field spikes, causing premature breakdown. Junction termination extension technology increases the radius of curvature by extending the charge distribution of the main junction horizontally, thus bringing the device's breakdown voltage closer to the theoretical value of an ideal parallel planar junction. However, traditional planar junction termination extension structures require a large chip area to achieve high voltage withstand, limiting the improvement of device power density. Trench termination offers significant advantages in reducing the termination area. However, in a single trench structure, the dielectric layer inside the trench generates a strong electric field, making it difficult for the breakdown voltage of the device to approach the theoretical value of an ideal parallel planar junction, thus limiting the application potential of gallium oxide power devices in higher voltage scenarios.
[0003] Therefore, how to design a new terminal structure that can achieve high breakdown voltage while effectively reducing the terminal area has become a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of existing junction termination extension structures with excessively large area and trench structures with limited withstand voltage, and to provide a gallium oxide power diode with a combined junction termination extension and trench termination structure and its fabrication method. Through complementary design, it can simultaneously achieve high breakdown voltage and high terminal area utilization efficiency.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: a gallium oxide power diode having a junction termination extension and trench composite termination structure, comprising a cathode metal layer, a highly doped n-type semiconductor substrate, a lightly doped n-type gallium oxide epitaxial layer, a p-type semiconductor layer, an anode metal layer and a passivation layer stacked sequentially from bottom to top; The cathode metal layer is deposited on the lower surface of the highly doped n-type semiconductor substrate to form an ohmic contact; the low-doped n-type gallium oxide epitaxial layer is disposed on the highly doped n-type semiconductor substrate; a trench is formed on the upper surface of the low-doped n-type gallium oxide epitaxial layer; the p-type semiconductor layer is disposed on the low-doped n-type gallium oxide epitaxial layer and extends laterally to cover part of the upper surface of the low-doped n-type gallium oxide epitaxial layer, and the p-type semiconductor layer covers the sidewalls and bottom of the trench when it extends laterally, thereby forming a junction termination extension and trench composite termination structure; the anode metal layer is disposed above the p-type semiconductor layer; the passivation layer covers part of the upper surfaces of the low-doped n-type gallium oxide epitaxial layer, the p-type semiconductor layer and the anode metal layer.
[0006] Furthermore, the material of the cathode metal layer is selected from at least one of Ti, Ni, Ag and Au, depending on the requirements.
[0007] Furthermore, the material of the highly doped n-type semiconductor substrate is selected from at least one of gallium oxide, silicon carbide, and silicon, depending on the requirements; the thickness of the highly doped n-type semiconductor substrate is 50-650 μm, and the doping concentration is 10. 18 -10 20 cm -3 .
[0008] Furthermore, the thickness of the lightly doped n-type gallium oxide epitaxial layer is 8-20 μm, and the doping concentration is 10. 15 -10 17 cm -3 .
[0009] Furthermore, the material of the p-type semiconductor layer is selected from at least one of p-type nickel oxide, p-type silicon carbide, p-type gallium nitride, and p-type gallium oxide, depending on the requirements; the thickness of the p-type semiconductor layer is 100-1000 nm, and the hole concentration is 10. 16 -10 18 cm -3 .
[0010] Furthermore, the trench width on the lightly doped n-type gallium oxide epitaxial layer ( W 2 The thickness of the p-type semiconductor layer is 2-20 μm, and its depth is 0.5-5 μm; the width of the p-type semiconductor layer from the edge of the anode metal layer to the edge of the trench on the nearest side is ( ). W 1 The width is 1-5 μm, extending laterally outward from the edge of the trench on the more distant side. W 3 The thickness ranges from 0.25 to 2.5 μm.
[0011] Furthermore, the material of the passivation layer is selected from at least one of polyimide (PI), silicon dioxide, silicon nitride, and SU-8 adhesive, depending on the requirements, and the thickness of the passivation layer is 1-10 μm.
[0012] Furthermore, the material of the anode metal layer is selected from at least one of Ni, Mo, W, Pt, Al, Au and Ag as required, and the width of the anode metal layer is 100-500 μm.
[0013] The present invention also provides a method for fabricating the above-mentioned gallium oxide power diode having a junction termination extension and trench composite termination structure, comprising the following steps: Step 1: Perform pretreatment on the highly doped n-type semiconductor substrate to remove surface particles and contaminants; Step 2: Deposit a lightly doped n-type gallium oxide epitaxial layer on the upper surface of the pretreated highly doped n-type semiconductor substrate; Step 3: Deposit a cathode metal layer on the lower surface of a highly doped n-type semiconductor substrate; Step 4: Spin-coat photoresist on the upper surface of the lightly doped n-type gallium oxide epitaxial layer, form a trench opening pattern using standard photolithography, and form the trench structure using inductively coupled plasma etching according to the trench opening pattern. Step 5: Spin-coat photoresist onto the upper surface of the sample obtained in Step 4, form a p-type semiconductor layer opening pattern using standard photolithography, and deposit a p-type semiconductor layer according to the p-type semiconductor layer opening pattern; Step 6: Spin-coat photoresist onto the upper surface of the sample obtained in Step 5, form an anode metal layer opening pattern using standard photolithography, and deposit the anode metal layer according to the anode metal layer opening pattern; Step 7: Spin-coat photoresist onto the upper surface of the sample obtained in Step 6, and form a passivation layer with an anode contact window on the device surface using standard photolithography.
[0014] The main features of the technical solution provided by this invention are twofold: First, the p-type semiconductor layer is extended outward from the anode edge to cover part of the upper surface of the gallium oxide epitaxial layer, forming a junction termination extension structure, which extends the charge distribution of the main junction, expands the radius of curvature, and alleviates the electric field concentration at the edge of the main junction; Second, a trench structure is set in the gallium oxide epitaxial layer, and part of the p-type semiconductor layer covers the trench sidewalls and bottom, forming a termination structure of junction termination extension and trench recombination, which forces the electric field to be distributed along the trench depth direction (longitudinal direction), thereby improving the uniformity of the electric field distribution.
[0015] Compared with existing technologies, this invention has the following advantages: it introduces a junction termination extension and trench composite termination structure into gallium oxide power diodes. First, by utilizing the junction termination extension structure, the charge distribution of the main junction is extended, and the radius of curvature is increased, causing the electric field lines emitted by the epitaxial layer ionization donors to partially point towards the junction termination extension region, thereby reducing the peak electric field at the edge of the main junction. Second, to overcome the disadvantage of the large chip area occupied by the junction termination extension structure, a trench structure is introduced, in which a portion of the p-type semiconductor layer covers the trench sidewalls and bottom, forcing the electric field to distribute along the trench depth direction (longitudinal direction). This reduces the lateral size of the termination region required for high voltage withstand capability and further improves the electric field concentration problem at the edge of the main junction, reducing the peak electric field at the edge of the main junction. Simultaneously, the p-type semiconductor layer covering the trench sidewalls and bottom, under full depletion, causes equipotential lines to be uniformly distributed around the trench, sharing the electric field lines emitted by the epitaxial layer ionization donors, reducing the peak electric field at the edge of the junction termination extension region, and effectively suppressing the strong electric field in the trench dielectric, avoiding the problem of premature dielectric breakdown present in conventional trench structures. Therefore, this structure can simultaneously improve the breakdown voltage of the device and the utilization efficiency of the terminal region through the complementary design of junction termination extension and trench composite termination structure. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of a gallium oxide power diode with junction termination extension and trench composite termination structure provided in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the fabrication method of a gallium oxide power diode with a junction termination extension and trench composite termination structure provided in this embodiment of the invention. Figure 3 This is a comparison chart of the breakdown characteristic curves of the gallium oxide power diode with junction termination extension and trench composite termination structure provided in the embodiments of the present invention, the gallium oxide power diode with conventional junction termination extension structure, the gallium oxide power diode with conventional trench structure, and the ideal parallel planar junction (gallium oxide / nickel oxide). Figure 4 This is a comparison diagram of the electric field distribution on the upper surface of the n-type gallium oxide epitaxial layer when the gallium oxide power diode with junction termination extension and trench composite termination structure provided in the embodiments of the present invention and the gallium oxide power diode with conventional trench structure break down; Figure 5 This is a comparison diagram of the electric field distribution on the upper surface of the n-type gallium oxide epitaxial layer when a gallium oxide power diode with junction termination extension and trench composite termination structure provided in the embodiments of the present invention and a gallium oxide power diode with conventional junction termination extension structure break down. Detailed Implementation
[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0018] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0020] like Figure 1 As shown, this embodiment provides a gallium oxide power diode with a junction termination extension and trench composite termination structure, characterized in that it includes a cathode metal layer 1, a highly doped n-type semiconductor substrate 2, a lightly doped n-type gallium oxide epitaxial layer 3, a p-type semiconductor layer 4, an anode metal layer 6, and a passivation layer 5 stacked sequentially from bottom to top. The cathode metal layer 1 is deposited on the lower surface of the highly doped n-type semiconductor substrate 2 to form an ohmic contact; the low-doped n-type gallium oxide epitaxial layer 3 is disposed on the highly doped n-type semiconductor substrate 2; a trench is formed on the upper surface of the low-doped n-type gallium oxide epitaxial layer 3; the p-type semiconductor layer 4 is disposed on the low-doped n-type gallium oxide epitaxial layer 3 and extends laterally to cover part of the upper surface of the low-doped n-type gallium oxide epitaxial layer 3, and the p-type semiconductor layer 4 covers the sidewalls and bottom of the trench when it extends laterally, thereby forming a junction termination extension and trench composite termination structure; the anode metal layer 6 is disposed above the p-type semiconductor layer 4; the passivation layer 5 covers part of the upper surfaces of the low-doped n-type gallium oxide epitaxial layer 3, the p-type semiconductor layer 4 and the anode metal layer 6.
[0021] The material of the cathode metal layer 1 can be selected from at least one of Ti, Ni, Ag and Au, depending on the requirements.
[0022] The material of the highly doped n-type semiconductor substrate 2 can be selected from at least one of gallium oxide, silicon carbide, and silicon, depending on the requirements; the thickness of the highly doped n-type semiconductor substrate 2 is 50-650 μm, and the doping concentration is 10. 18 -10 20 cm -3 .
[0023] The thickness of the lightly doped n-type gallium oxide epitaxial layer 3 is 8-20 μm, and the doping concentration is 10. 15 -10 17 cm -3 .
[0024] The material of the p-type semiconductor layer 4 can be selected from at least one of p-type nickel oxide, p-type silicon carbide, p-type gallium nitride, and p-type gallium oxide, depending on the requirements; the thickness of the p-type semiconductor layer 4 is 100-1000 nm, and the hole concentration is 10. 16 -10 18 cm -3 .
[0025] The trench width on the low-doped n-type gallium oxide epitaxial layer 3 ( W 2 The thickness of the p-type semiconductor layer 4 is 2-20 μm, and its depth is 0.5-5 μm; the width of the p-type semiconductor layer 4 from the edge of the anode metal layer 6 to the edge of the trench on the nearest side is ( W 1 The width is 1-5 μm, extending laterally outward from the edge of the trench on the more distant side. W 3 The thickness ranges from 0.25 to 2.5 μm.
[0026] The material of the passivation layer 5 can be selected from polyimide (PI), silicon dioxide, silicon nitride, SU-8 adhesive, etc., depending on the requirements, and the thickness of the passivation layer is 1-10 μm.
[0027] The material of the anode metal layer 6 can be selected from at least one of Ni, Mo, W, Pt, Al, Au and Ag, depending on the requirements, and the width of the anode metal layer is 100-500 μm.
[0028] like Figure 2 As shown, this embodiment provides a method for fabricating the gallium oxide power diode with the above-mentioned junction termination extension and trench composite termination structure, including the following steps: Step 1: Perform a pretreatment on the highly doped n-type semiconductor substrate 2 to remove surface particles and contaminants; Step 2: Deposit a lightly doped n-type gallium oxide epitaxial layer 3 on the upper surface of the pretreated highly doped n-type semiconductor substrate 2; Step 3: Deposit a cathode metal layer 1 on the lower surface of the highly doped n-type semiconductor substrate 2; Step 4: Spin-coat photoresist on the upper surface of the low-doped n-type gallium oxide epitaxial layer 3, form a trench opening pattern using standard photolithography, and form the trench structure using inductively coupled plasma (ICP) etching according to the trench opening pattern. Step 5: Spin-coat photoresist onto the upper surface of the sample obtained in Step 4, form a p-type semiconductor layer opening pattern using standard photolithography, and deposit p-type semiconductor layer 4 according to the p-type semiconductor layer opening pattern; Step 6: Spin-coat photoresist onto the upper surface of the sample obtained in step 5, form an anode metal layer opening pattern using standard photolithography, and deposit the anode metal layer 6 according to the anode metal layer opening pattern; Step 7: Spin-coat photoresist onto the upper surface of the sample obtained in Step 6, and form a passivation layer 5 with an anode contact window on the device surface using a standard photolithography process.
[0029] In step 2, a low-doped n-type gallium oxide epitaxial layer 3 can be grown on the surface of the pretreated highly doped n-type semiconductor substrate 2 using hydride vapor phase epitaxy (HVPE) or metal-organic chemical vapor deposition (MOCVD) processes, but is not limited to these methods.
[0030] In steps 3 and 6, one or more sputtering processes, including magnetron sputtering, thermal evaporation, and electron beam evaporation, can be used to deposit the metal layer, but are not limited to these methods.
[0031] When the passivation layer material in step 7 is selected as PI or SU-8 adhesive, a standard photolithography process can be used to form the passivation layer.
[0032] In this embodiment, the cathode metal layer 1 is made of Ni / Au. The highly doped n-type semiconductor substrate 2 is made of n-type gallium oxide, with a thickness of 500 μm and a doping concentration of 2 × 10⁻⁶. 18 cm -3 The thickness of the lightly doped n-type gallium oxide epitaxial layer 3 is 10 μm, and the doping concentration is 1.2 × 10⁻⁶. 16 cm -3 The p-type semiconductor layer 4 is made of p-type nickel oxide with a thickness of 400 nm and a hole concentration of 5 × 10⁴. 17 cm -3 ; trench width ( W 2 The thickness is 10 μm and the depth is 2 μm; among which, the width of the p-type semiconductor layer 4 from the anode edge to the trench edge is ( W 1 The width is 2.5 μm, extending laterally outward from the edge of the trench. W 3 The passivation layer 5 is made of silicon dioxide and has a thickness of 5 μm. The anode metal layer 6 is made of Ni / Au and has a width of 180 μm.
[0033] Based on the above selections and designs, this embodiment provides the following specific implementation method: Step 1: Apply a 500 μm thick material with a doping concentration of 2 × 10⁻⁶. 18 cm -3 The highly doped n-type gallium oxide substrate 2 is pretreated to remove surface particles and stains.
[0034] Step 2: Using MOCVD technology, an epitaxial growth process is performed on the surface of the pretreated highly doped n-type gallium oxide substrate 2 to grow a 10 μm thick substrate with a doping concentration of 1.2 × 10⁻⁶. 16 cm -3 3. Low-doped n-type gallium oxide epitaxial layer.
[0035] Step 3: Ni and Au are sequentially deposited on the lower surface of the highly doped n-type gallium oxide substrate 2 using electron beam evaporation to form cathode metal 1.
[0036] Step 4: Spin-coat photoresist on the surface of the low-doped n-type gallium oxide epitaxial layer 3, and form a trench opening pattern using standard photolithography. Based on the opening pattern, form a trench structure with a width of 10 μm and a depth of 2 μm using inductively coupled plasma (ICP) etching.
[0037] Step 5: Spin-coat photoresist onto the sample surface and form a p-type semiconductor layer 4 opening pattern using standard photolithography. Deposit a layer with a thickness of 400 nm and a hole concentration of 5 × 10⁴ nm according to the opening pattern. 17 cm -3 p-type nickel oxide.
[0038] Step 6: Spin-coat photoresist onto the upper surface of the sample, and use standard photolithography to form the anode metal 6 opening pattern, and then deposit Ni and Au sequentially to form the anode metal 6.
[0039] Step 7: Spin-coat photoresist onto the upper surface of the sample, and form a silicon dioxide passivation layer with an anode contact window on the device surface with a thickness of 5 μm using standard photolithography.
[0040] The working principle of this invention is as follows: First, by extending a p-type semiconductor layer from the anode edge outward to cover part of the upper surface of the gallium oxide epitaxial layer, a junction termination extension structure is formed, extending the charge distribution of the main junction, increasing the radius of curvature, and alleviating the electric field concentration at the edge of the main junction. Second, a trench structure is formed in the gallium oxide epitaxial layer, and part of the p-type semiconductor layer covers the trench sidewalls and bottom, forming a termination structure of junction termination extension and trench recombination. This forces the electric field to be distributed along the trench depth direction (longitudinal direction), simultaneously reducing the peak electric field at the edge of the main junction and the edge of the junction termination extension region, and reducing the lateral size of the device termination region. Furthermore, the p-type semiconductor layer covering the trench sidewalls and bottom ensures that the equipotential lines are uniformly distributed around the trench under full depletion, effectively suppressing the strong electric field in the trench dielectric and avoiding the problem of premature dielectric breakdown in conventional trench structures. Therefore, the complementary design of this structure can effectively optimize the electric field distribution and improve the utilization efficiency of the termination region, thereby significantly enhancing the application potential of gallium oxide power devices in higher voltage scenarios.
[0041] Figure 3A comparison of breakdown characteristic curves is provided for a gallium oxide power diode with a preferred embodiment of the present invention, featuring a junction-terminated extension and trench composite termination structure; a gallium oxide power diode with a conventional junction-terminated extension structure; a gallium oxide power diode with a conventional trench structure; and an ideal parallel planar junction (gallium oxide / nickel oxide). From... Figure 3 It can be seen that the breakdown voltage of a conventional trench-structured gallium oxide power diode is 3214 V, which is only 70% of the breakdown voltage (4573 V) of an ideal parallel planar junction (gallium oxide / nickel oxide). The breakdown voltage of a gallium oxide power diode with junction extension and trench composite termination structure and a conventional junction extension structure is 4223 V, which is close to more than 90% of the breakdown voltage (4573 V) of an ideal planar junction (gallium oxide / nickel oxide).
[0042] Figure 4 A comparison of the electric field distribution on the upper surface of the n-type gallium oxide epitaxial layer during breakdown is presented for a gallium oxide power diode with a junction-terminated extension and trench composite termination structure according to a preferred embodiment of the present invention, and a conventional trench structure gallium oxide power diode. It should be noted that, due to the left-right symmetry of the device's termination structure, a semi-symmetric model (i.e., retaining only the right half of the structure) is used in this simulation to improve computational efficiency and optimize finite element mesh resource allocation. Figure 4 It can be seen that the electric field distribution of conventional trench-structured gallium oxide power diodes is relatively uniform and exhibits significant electric field spikes, limiting further improvements in device breakdown voltage. Gallium oxide power diodes with junction termination extension and trench composite termination structures demonstrate a more uniform electric field distribution. This is mainly because the structure extends the charge distribution of the main junction, increases the radius of curvature, and effectively alleviates the electric field concentration at the edge of the main junction. Furthermore, the p-type semiconductor layer covering the trench sidewalls and bottom ensures a uniform distribution of equipotential lines around the trench under full depletion, effectively suppressing the electric field spikes in the trench dielectric.
[0043] Figure 5 A comparison diagram of the upper surface electric field distribution of the n-type gallium oxide epitaxial layer during breakdown is provided, showing a gallium oxide power diode with a junction-terminated extension and trench composite termination structure according to a preferred embodiment of the present invention, and a gallium oxide power diode with a conventional junction-terminated extension structure. According to... Figure 3 As shown, although the breakdown voltage of gallium oxide power diodes with junction-terminated extension and trench composite termination structures is almost identical to that of gallium oxide power diodes with conventional junction-terminated extension structures, and is more than 90% of the breakdown voltage (4573 V) of an ideal planar junction (gallium oxide / nickel oxide), from... Figure 5 It can be seen that the gallium oxide power diode with junction termination extension and trench composite termination structure reduces the termination area by more than 60% compared with the gallium oxide power diode with conventional junction termination extension structure, thereby improving the utilization efficiency of the device termination area.
[0044] This invention addresses the technical problems of existing technologies, such as the large area occupied by junction termination extension structures and the limited voltage withstand capability of trench structures, by proposing a gallium oxide power diode with a junction termination extension and trench composite termination structure and its fabrication method. First, a p-type semiconductor layer is extended outward from the anode edge to cover part of the upper surface of the gallium oxide epitaxial layer, forming a junction termination extension structure. This structure extends the charge distribution of the main junction, increases the radius of curvature, and effectively alleviates the electric field concentration at the edge of the main junction. Second, a trench structure is formed in the gallium oxide epitaxial layer, and part of the p-type semiconductor layer covers the trench sidewalls and bottom, forming a termination structure with junction termination extension and trench composite. This structure forces the electric field to distribute along the trench depth direction (longitudinal direction), which on the one hand further alleviates the electric field concentration at the edge of the main junction and reduces the peak electric field at the edge of the junction termination extension region, and on the other hand reduces the lateral size of the device termination region. Furthermore, the p-type semiconductor layer covering the trench sidewalls and bottom ensures that the equipotential lines are uniformly distributed around the trench under full depletion, effectively suppressing the strong electric field in the trench dielectric and avoiding the problem of premature dielectric layer breakdown in conventional trench structures. Therefore, the complementary design of this structure effectively optimizes the electric field distribution and reduces the terminal area, thereby significantly enhancing the application potential of gallium oxide power devices in higher voltage scenarios.
[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A gallium oxide power diode having a junction termination extension and a trench-combined termination structure, characterized by, The cathode metal layer (1), the high-doped n-type semiconductor substrate (2), the low-doped n-type gallium oxide epitaxial layer (3), the p-type semiconductor layer (4), the anode metal layer (6) and the passivation layer (5) are sequentially stacked from bottom to top. The cathode metal layer (1) is deposited on the lower surface of the high-doped n-type semiconductor substrate (2) to form an ohmic contact; the low-doped n-type gallium oxide epitaxial layer (3) is arranged on the high-doped n-type semiconductor substrate (2); the upper surface of the low-doped n-type gallium oxide epitaxial layer (3) is provided with a groove; the p-type semiconductor layer (4) is arranged on the low-doped n-type gallium oxide epitaxial layer (3) and extends laterally to cover part of the upper surface of the low-doped n-type gallium oxide epitaxial layer (3), and the p-type semiconductor layer (4) covers the sidewall and the bottom of the groove when extending laterally, so as to form a junction terminal expansion and groove composite terminal structure; the anode metal layer (6) is arranged above the p-type semiconductor layer (4); and the passivation layer (5) covers part of the upper surfaces of the low-doped n-type gallium oxide epitaxial layer (3), the p-type semiconductor layer (4) and the anode metal layer (6).
2. The gallium oxide power diode having a junction termination extension and a trench-combined termination structure according to claim 1, characterized by, The material of the cathode metal layer (1) is at least one of Ti, Ni, Ag and Au according to requirements.
3. The gallium oxide power diode having a junction termination extension and a trench-combined termination structure according to claim 1, characterized by, The material of the high-doped n-type semiconductor substrate (2) is selected from at least one of gallium oxide, silicon carbide and silicon according to requirements; the thickness of the high-doped n-type semiconductor substrate (2) is 50-650 μm, and the doping concentration is 10 18 -10 20 cm -3 .
4. The gallium oxide power diode having a junction termination extension and a trench-combined termination structure according to claim 1, characterized by, The thickness of the low-doped n-type gallium oxide epitaxial layer (3) is 8-20 μm, and the doping concentration is 10 15 -10 17 cm -3 .
5. The gallium oxide power diode with junction termination extension and trench-combined termination structure according to claim 1, wherein The material of the p-type semiconductor layer (4) is selected from at least one of p-type nickel oxide, p-type silicon carbide, p-type gallium nitride and p-type gallium oxide according to requirements; the thickness of the p-type semiconductor layer (4) is 100-1000 nm, and the hole concentration is 10 16 -10 18 cm -3 .
6. The gallium oxide power diode with junction termination extension and trench-combined termination structure according to claim 1, characterized in that, The trench width on the low-doped n-type gallium oxide epitaxial layer (3) is ( W 2 The thickness of the p-type semiconductor layer (4) is 2-20 μm, and its depth is 0.5-5 μm; the width of the p-type semiconductor layer (4) from the edge of the anode metal layer (6) to the edge of the trench on the nearest side is ( ). W 1 The width is 1-5 μm, extending laterally outward from the edge of the trench on the more distant side. W 3 The thickness ranges from 0.25 to 2.5 μm.
7. The gallium oxide power diode with junction termination extension and trench-combined termination structure according to claim 1, wherein The material of the passivation layer (5) is at least one of polyimide (PI), silicon dioxide, silicon nitride and SU-8 glue according to requirements, and the thickness of the passivation layer is 1-10 μm.
8. The gallium oxide power diode having a junction termination extension and a trench-composite termination structure according to claim 1, wherein, The material of the anode metal layer (6) is at least one of Ni, Mo, W, Pt, Al, Au and Ag according to requirements, and the width of the anode metal layer is 100-500 μm.
9. The method of fabricating a gallium oxide power diode with junction termination extension and trench-combined termination structure according to any one of claims 1-8, wherein The method comprises the following steps: Step 1: the high-doped n-type semiconductor substrate (2) is pretreated to remove surface particles and stains; Step 2: the low-doped n-type gallium oxide epitaxial layer (3) is deposited on the upper surface of the pretreated high-doped n-type semiconductor substrate (2); Step 3: the cathode metal layer (1) is deposited on the lower surface of the high-doped n-type semiconductor substrate (2); Step 4: photoresist is spin-coated on the upper surface of the low-doped n-type gallium oxide epitaxial layer (3), a standard photolithography process is used to form a groove opening pattern, and a groove structure is formed according to the groove opening pattern by using inductively coupled plasma etching; Step 5: photoresist is spin-coated on the upper surface of the sample obtained in step 4, a standard photolithography process is used to form a p-type semiconductor layer opening pattern, and the p-type semiconductor layer (4) is deposited according to the p-type semiconductor layer opening pattern; Step 6: photoresist is spin-coated on the upper surface of the sample obtained in step 5, a standard photolithography process is used to form an anode metal layer opening pattern, and the anode metal layer (6) is deposited according to the anode metal layer opening pattern; Step 7: photoresist is spin-coated on the upper surface of the sample obtained in step 6, and a passivation layer (5) with an anode contact window is formed on the surface of the device by using a standard photolithography process.