A high-temperature pin ultraviolet detector and a preparation method thereof

Abstract

The application discloses a high-temperature pin ultraviolet detector and belongs to the technical field of microelectronics, comprising a 4H-SiC substrate, a 4H-SiC epitaxial layer, a 4H-SiC absorption layer and a 4H-SiC contact layer which are stacked from bottom to top; the 4H-SiC contact layer, the 4H-SiC absorption layer and the 4H-SiC epitaxial layer are formed into a tilt mesa structure through etching on both sides; a plurality of inverted trapezoidal grooves are etched in the middle of the 4H-SiC contact layer; the whole upper surface of the device is covered with a passivation layer; P-type and N-type ohmic contact metals are arranged on the lower mesa and the upper mesa of the tilt mesa structure respectively; a metal pad is arranged above the P-type and N-type ohmic contact metals; and a diffusion barrier layer is further arranged between the metal pad and the P / N-type ohmic contact metals. The structural design improves the thermal stability of the ohmic contact and the service life in a high-temperature environment, thereby improving the performance of the device.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology, specifically relating to a high-temperature pin ultraviolet detector and its preparation method. Background Technology

[0002] Ultraviolet (UV) detection is a commonly used analytical technique widely applied in fields such as optical communication, flame detection, combustion monitoring, chemical analysis, and astronomy. Most of these applications require UV instruments capable of operating in harsh, high-temperature environments. Over the past decade, wide-bandgap semiconductors have become the most attractive materials in optoelectronics. Their wide bandgap and inherent properties have driven the development of reliable photodetectors capable of selectively detecting short wavelengths (i.e., ultraviolet, UV) in high-temperature regions (up to 300°C).

[0003] The bandgap of 4H-SiC material is 3.26 eV, which directly determines the high-temperature operating capability of 4H-SiC devices. Compared to Si and GaAs, 4H-SiC has a wider bandgap, resulting in a lower intrinsic carrier concentration. This lower intrinsic carrier concentration means that 4H-SiC-based devices have lower leakage current when operating in high-temperature environments. The maximum operating temperature of 4H-SiC can reach 1000℃.

[0004] Common ultraviolet (UV) detectors include photoconductive photodetectors, metal-semiconductor-metal photodetectors, Schottky, pn, and pin junction photodetectors. Among these, pin junction photodetectors are more suitable for high-temperature applications due to their simple fabrication process and low leakage current. The main driving force behind the development of high-temperature UV detection instruments is the need for on-site monitoring of harsh environments and processes that generate UV signals in industrial, automotive, aerospace, and energy production systems. Therefore, researching and designing high-performance 4H-SiC high-temperature UV detectors is undoubtedly of great significance.

[0005] For device manufacturing, the fabrication of ohmic contacts is an essential and critical process. In high-temperature environments (>450℃), the thermal stability of ohmic contacts is crucial; their degradation can lead to performance degradation or even failure of the entire device. For 4H-SiC devices operating under extreme high-temperature conditions, a high-temperature resistant ohmic contact is indispensable. If the ohmic contact is not heat-resistant or has poor thermal stability, then the high-temperature properties of the 4H-SiC material cannot be realized.

[0006] Existing ohmic contacts mainly include Ni / SiC ohmic contacts and Pt / Ti / SiC ohmic contacts. Among them, Ni / SiC ohmic contact technology is the most mature and has been widely used in commercial applications due to its simple process and low contact resistance. High-temperature processing is an unavoidable process for forming ohmic contacts, during which some carbon elements in SiC diffuse into Ni. However, since the carbon elements diffused into Ni cannot combine with Ni and remain as free carbon, this poses a challenge to subsequent wire bonding processes. In addition, Ni / SiC ohmic contacts degrade under prolonged high-temperature operation. The rapid failure of Pt / Ti / SiC ohmic contacts is due to the severe oxidation of Ti atoms at the metal / SiC interface. For high-temperature resistant devices, the high-temperature environment causes surface oxygen atoms to diffuse rapidly towards SiC, thus leading to ohmic contact degradation. Summary of the Invention

[0007] To address the problem of device failure at high temperatures due to ohmic contact degradation in existing technologies, this invention provides a high-temperature pin ultraviolet detector and its fabrication method. The technical problem solved by this invention is achieved through the following technical solution:

[0008] In a first aspect, the present invention proposes a high-temperature pin ultraviolet detector, comprising a 4H-SiC substrate, a 4H-SiC epitaxial layer, a 4H-SiC absorption layer, a 4H-SiC contact layer, a passivation layer, a P-type ohmic contact metal, an N-type ohmic contact metal, a metal pad, and a diffusion barrier layer.

[0009] A 4H-SiC substrate, a 4H-SiC epitaxial layer, a 4H-SiC absorber layer, and a 4H-SiC contact layer are stacked from bottom to top.

[0010] The 4H-SiC contact layer, the 4H-SiC absorber layer, and the two sides of the 4H-SiC epitaxial layer are etched to form an angled mesa structure. The upper surface of the 4H-SiC contact layer forms the upper mesa of the angled mesa structure, and the sidewalls of the 4H-SiC contact layer, the sidewalls of the 4H-SiC absorber layer, and part of the sidewalls of the 4H-SiC epitaxial layer together form the inclined sidewalls of the angled mesa structure. The upper surfaces on both sides of the 4H-SiC epitaxial layer form the lower mesa of the angled mesa structure.

[0011] Several inverted trapezoidal trenches are etched in the middle of the 4H-SiC contact layer, and these inverted trapezoidal trenches extend downward from the upper surface of the 4H-SiC contact layer to the interior of the 4H-SiC contact layer.

[0012] The passivation layer covers the entire upper surface of the device;

[0013] P-type ohmic contact metal is disposed on the lower platform of the tilted platform structure, comprising Ni / W / TaSi2 / Ti / Pt stacked sequentially;

[0014] N-type ohmic contact metal is disposed on the upper platform of the tilted platform structure, comprising Ti / TaSi2 / Ti / Pt stacked sequentially;

[0015] The metal pad is positioned above the P-type ohmic contact metal and the N-type ohmic contact metal;

[0016] A diffusion barrier layer is provided between the metal Pad and the P-type ohmic contact metal, and between the metal Pad and the N-type ohmic contact metal. The diffusion barrier layer includes metal Ti / Pt.

[0017] Secondly, this invention proposes a method for fabricating a high-temperature pin ultraviolet detector, which includes the following steps:

[0018] A 4H-SiC epitaxial layer, a 4H-SiC absorber layer, and a 4H-SiC contact layer are sequentially formed on a 4H-SiC substrate.

[0019] The 4H-SiC contact layer, 4H-SiC absorber layer, and 4H-SiC epitaxial layer are etched to form an angled mesa structure. The upper surface of the 4H-SiC contact layer forms the upper mesa of the angled mesa structure, and the sidewalls of the 4H-SiC contact layer, the sidewalls of the 4H-SiC absorber layer, and part of the sidewalls of the 4H-SiC epitaxial layer together form the inclined sidewalls of the angled mesa structure. The upper surfaces on both sides of the 4H-SiC epitaxial layer form the lower mesa of the angled mesa structure.

[0020] The middle position of the 4H-SiC contact layer is etched to form several inverted trapezoidal trenches;

[0021] A passivation layer is formed on the entire sample surface;

[0022] P-type ohmic contact metal and N-type ohmic contact metal are fabricated on the lower and upper mesa of the tilted mesa structure, respectively; wherein, the P-type ohmic contact metal comprises Ni / W / TaSi2 / Ti / Pt stacked sequentially, and the N-type ohmic contact metal comprises Ti / TaSi2 / Ti / Pt stacked sequentially.

[0023] A diffusion barrier layer is formed on the P-type ohmic contact metal and the N-type ohmic contact metal; the diffusion barrier layer metal is Ti / Pt;

[0024] A metal pad is formed on the diffusion barrier layer, thereby completing the device fabrication.

[0025] The beneficial effects of this invention are:

[0026] The high-temperature pin ultraviolet detector proposed in this invention employs an N-type ohmic contact Ti / TaSi2 / Ti / Pt and a P-type ohmic contact Ni / W / TaSi2 / Ti / Pt, with Ti / Pt serving as a diffusion barrier layer. This diffusion barrier layer effectively prevents the migration of Au and O elements from the metal pad into the epitaxial layer, significantly reducing further diffusion of Au and O through the barrier. The TaSi2 layer also effectively slows down the diffusion rate of O atoms towards SiC, further improving the thermal stability and lifetime of the ohmic contact at high temperatures. Simultaneously, the introduction of metallic Ni lowers the annealing temperature required for the formation of the P-type ohmic contact. Furthermore, metallic W can bind C to react with the free C generated by the Ni-based ohmic contact, keeping the contact resistance of the N-type and P-type contacts essentially stable, thereby improving the thermal stability and lifetime of the ohmic contact at high temperatures.

[0027] 2. The high-temperature pin ultraviolet detector proposed in this invention features a trapezoidal groove structure, which can reduce light reflection while enabling the absorption region I to absorb more photons, thereby improving the responsivity of the photodetector and enhancing its detectivity and performance.

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a high-temperature pin ultraviolet detector provided in an embodiment of the present invention;

[0030] Figure 2 This is a schematic flowchart of a method for fabricating a high-temperature pin ultraviolet detector provided in an embodiment of the present invention;

[0031] Figure 3a-3k This is a schematic diagram illustrating the fabrication process of the high-temperature pin ultraviolet detector provided in an embodiment of the present invention;

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-4H-SiC substrate, 2-4H-SiC epitaxial layer, 3-4H-SiC absorber layer, 4-4H-SiC contact layer, 5-passivation layer, 6-P-type ohmic contact metal, 7-N-type ohmic contact metal, 8-metal pad, 9-diffusion barrier layer. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] For ohmic contact structures, high-temperature environments can cause ohmic contact degradation, leading to device aging. Analysis reveals that at high temperatures, over time, the degradation of ohmic contacts in 4H-SiC sensors and electronic devices is driven by two main failure mechanisms: 1. Migration of Au and O from the surface to the ohmic contact / SiC interface, resulting in rectification. 2. Intermetallic mixing between the diffusion barrier layer and the potential ohmic contact metallization, leading to increased resistance. The degradation of ohmic contacts ultimately results in device failure.

[0036] Based on this, the first aspect of the present invention proposes a high-temperature pin ultraviolet detector. Please refer to... Figure 1 , Figure 1 This is a schematic diagram of the structure of a high-temperature pin ultraviolet detector provided in an embodiment of the present invention. The device includes a 4H-SiC substrate 1, a 4H-SiC epitaxial layer 2, a 4H-SiC absorption layer 3, a 4H-SiC contact layer 4, a passivation layer 5, a P-type ohmic contact metal 6, an N-type ohmic contact metal 7, a metal pad 8, and a diffusion barrier layer 9.

[0037] A 4H-SiC substrate 1, a 4H-SiC epitaxial layer 2, a 4H-SiC absorber layer 3, and a 4H-SiC contact layer 4 are stacked from bottom to top;

[0038] The 4H-SiC contact layer 4, the 4H-SiC absorber layer 3, and the 4H-SiC epitaxial layer 2 are etched to form an inclined mesa structure on both sides. The upper surface of the 4H-SiC contact layer 4 forms the upper mesa of the inclined mesa structure, and the sidewalls of the 4H-SiC contact layer 4, the sidewalls of the 4H-SiC absorber layer 3, and part of the sidewalls of the 4H-SiC epitaxial layer 2 together form the inclined sidewalls of the inclined mesa structure. The upper surfaces on both sides of the 4H-SiC epitaxial layer 2 form the lower mesa of the inclined mesa structure.

[0039] Several inverted trapezoidal trenches are etched in the middle of the 4H-SiC contact layer 4, and these inverted trapezoidal trenches extend downward from the upper surface of the 4H-SiC contact layer 4 into the interior of the 4H-SiC contact layer 4.

[0040] Passivation layer 5 covers the entire upper surface of the device;

[0041] P-type ohmic contact metal 6 is disposed on the lower platform of the tilted platform structure, including Ni / W / TaSi2 / Ti / Pt stacked sequentially;

[0042] N-type ohmic contact metal 7 is disposed on the upper platform of the tilted platform structure, including Ti / TaSi2 / Ti / Pt stacked sequentially;

[0043] Metal Pad8 is positioned above P-type ohmic contact metal 6 and N-type ohmic contact metal 7;

[0044] A diffusion barrier layer 9 is provided between the metal Pad8 and the P-type ohmic contact metal 6, and between the metal Pad8 and the N-type ohmic contact metal 7. The diffusion barrier layer 9 includes metal Ti / Pt.

[0045] Specifically, in this embodiment, the 4H-SiC substrate 1 is n+ doped; the 4H-SiC epitaxial layer 2 is p+ doped with a doping concentration of 5 × 10⁻⁶. 18 -5.0×10 19 cm -3 The doping element is Al; the 4H-SiC absorber layer 3 is n-doped with a carrier concentration of 1.0 × 10⁻⁶. 15 -1.0×10 16 cm -3 The 4H-SiC contact layer 4 is n+ doped with a carrier concentration of 5.0 × 10⁴. 18 -1.0×10 19 cm -3 .

[0046] Optionally, as one implementation, the thickness of the 4H-SiC substrate 1 can be 350 μm or 2 μm, the thickness of the 4H-SiC absorber layer 3 can be 1 μm, and the thickness of the 4H-SiC contact layer 4 can be 0.5 μm.

[0047] Furthermore, the depth of the inverted trapezoidal groove can be 0.2-0.4 μm, and the width can be 1-2 μm;

[0048] Optionally, passivation layer 5 can be SiO2 / SiN. x The composite layer has a thickness of 20-30 nm.

[0049] Optionally, the material of the metal Pad8 is TaSi2 / Pt / Au.

[0050] The high-temperature pin ultraviolet detector proposed in this invention employs an N-type ohmic contact Ti / TaSi2 / Ti / Pt and a P-type ohmic contact Ni / W / TaSi2 / Ti / Pt, with Ti / Pt serving as a diffusion barrier layer. This diffusion barrier layer effectively prevents the migration of Au and O elements from the metal pad into the epitaxial layer, significantly reducing further diffusion of Au and O through the barrier. Furthermore, the TaSi2 layer effectively slows down the diffusion rate of O atoms towards SiC, further improving the thermal stability and lifetime of the ohmic contact at high temperatures. Simultaneously, the introduction of metallic Ni lowers the annealing temperature required for the formation of the P-type ohmic contact. Moreover, metallic W can bind C to react with the free C generated by the Ni-based ohmic contact, keeping the contact resistance of the N-type and P-type contacts essentially stable, thereby improving the thermal stability and lifetime of the ohmic contact at high temperatures.

[0051] Furthermore, the high-temperature pin ultraviolet detector proposed in this invention features a trapezoidal groove structure, which reduces light reflection while enabling the absorption region I to absorb more photons, thereby improving the responsivity of the photodetector and enhancing its detectivity and performance.

[0052] A second aspect of the present invention also provides a method for fabricating a high-temperature pin ultraviolet detector; please refer to [link to relevant documentation]. Figure 2 , Figure 2 This is a flowchart illustrating a method for fabricating a high-temperature pin ultraviolet detector according to an embodiment of the present invention. The method specifically includes the following steps:

[0053] Step 1: Sequentially form a 4H-SiC epitaxial layer, a 4H-SiC absorber layer, and a 4H-SiC contact layer on a 4H-SiC substrate.

[0054] First, an n+ type 4H-SiC substrate with a thickness of 350 μm is provided;

[0055] Then, a 2 μm thick p+ type 4H-SiC epitaxial layer was epitaxially grown on an n+ type 4H-SiC substrate using conventional CVD (Chemical Vapor Deposition) process.

[0056] Next, an n-type 4H-SiC absorber layer with a thickness of 1 μm was epitaxially grown on the p+ type 4H-SiC epitaxial layer using CVD process;

[0057] Finally, an n+ type 4H-SiC contact layer with a thickness of 0.5 μm was epitaxially grown on the n- type 4H-SiC absorber layer using a CVD process.

[0058] Step 2: Etch the 4H-SiC contact layer, 4H-SiC absorber layer and 4H-SiC epitaxial layer to form an angled mesa structure.

[0059] The upper surface of the 4H-SiC contact layer forms the upper mesa of the tilted mesa structure, and the sidewalls of the 4H-SiC contact layer, the sidewalls of the 4H-SiC absorption layer, and part of the sidewalls of the 4H-SiC epitaxial layer together form the tilted sidewalls of the tilted mesa structure; the upper surfaces on both sides of the 4H-SiC epitaxial layer form the lower mesa of the tilted mesa structure.

[0060] Step 3: Etch the middle position of the 4H-SiC contact layer to form several inverted trapezoidal trenches.

[0061] Step 4: Form a passivation layer on the entire sample surface.

[0062] Step 5: Prepare P-type ohmic contact metal and N-type ohmic contact metal on the lower and upper platforms of the tilted platform structure, respectively;

[0063] Among them, the P-type ohmic contact metal includes Ni / W / TaSi2 / Ti / Pt stacked sequentially, and the N-type ohmic contact metal includes Ti / TaSi2 / Ti / Pt stacked sequentially.

[0064] Specifically, photolithography, etching, and magnetron sputtering processes can be used to sequentially grow 100nm Ni, 30nm W, 400nm TaSi2, 100nm Ti, and 300nm Pt on the lower mesa of the tilted mesa structure to form a P-type ohmic contact metal.

[0065] Correspondingly, 100nm Ti, 300nm TaSi2, 100nm Ti, and 300nm Pt can be sequentially grown on the upper mesa of the tilted mesa structure using photolithography, etching, and magnetron sputtering processes to form an N-type ohmic contact metal.

[0066] The preparation order of P-type ohmic contact metal and N-type ohmic contact metal can be interchanged.

[0067] Step 6: Form diffusion barrier layers on the P-type ohmic contact metal and the N-type ohmic contact metal; the diffusion barrier layer metal is Ti / Pt.

[0068] Specifically, 100 nm Ti and 300 nm Pt were sequentially grown on P-type ohmic contact metal and N-type ohmic contact metal using magnetron sputtering technology to form diffusion barrier layers.

[0069] Step 7: Form a metal pad on the diffusion barrier layer to complete the device fabrication.

[0070] Specifically, a 20nm TaSi2, a 100nm Pt, and a 1μm Au layer can be sequentially grown on the diffusion barrier layer to form a metal Pad.

[0071] The fabrication of the device is now complete.

[0072] The following is a specific example, combined with Figure 3a-3k The schematic diagram shown illustrates the fabrication process of the high-temperature pin ultraviolet detector of the present invention, providing a detailed explanation.

[0073] S1. Provide an n+ type 4H-SiC substrate 1 with a thickness of 350μm, such as Figure 3a As shown.

[0074] S2. Using conventional CVD processes, a 2 μm thick p+ type 4H-SiC epitaxial layer 2 is epitaxially grown on an n+ type 4H-SiC substrate 1, such as... Figure 3bAs shown. The doping concentration of the P+ type 4H-SiC epitaxial layer 2 is 5 × 10⁻⁶. 18 -5.0×10 19 cm -3 The doping element is Al.

[0075] S3. Using CVD technology, an n-type 4H-SiC absorber layer 3 with a thickness of 1 μm is epitaxially grown on the p+ type 4H-SiC epitaxial layer 2, such as... Figure 3c As shown. The carrier concentration of the n-type 4H-SiC absorber layer 3 is 1.0 × 10⁻⁶. 15 -1.0×10 16 cm -3 .

[0076] S4. An n+ type 4H-SiC contact layer 4 with a thickness of 0.5 μm is epitaxially grown on the n- type 4H-SiC absorber layer 3 using a CVD process, such as... Figure 3d As shown. The carrier concentration of the n+ type 4H-SiC contact layer 4 is 5.0 × 10⁻⁶. 18 -1.0×10 19 cm -3 .

[0077] S5. Using photoresist reflow technology and inductively coupled plasma etching (ICP) process, the tilted mesa structure of the device is etched, such as... Figure 3e As shown.

[0078] S6. Etch the surface of the n+ type 4H-SiC contact layer 4 to form inverted trapezoidal trenches with a depth of 0.2-0.4 μm and a width of 1-2 μm, such as... Figure 3f As shown.

[0079] S7. Growing SiO2 / SiN using thermal oxidation and PECVD processes. x The composite layer serves as passivation layer 5, with a thickness of 20nm-30nm. Figure 3g As shown.

[0080] S8. Using photolithography, etching, and magnetron sputtering processes, 100nm Ti, 300nm TaSi2, 100nm Ti, and 300nm Pt are sequentially grown on the upper mesa of the tilted mesa structure, followed by rapid thermal annealing in a vacuum at 800℃ for 10s to form an N-type ohmic contact metal 7. Figure 3h As shown.

[0081] S9. Using photolithography, etching, and magnetron sputtering processes, 100nm Ni, 30nm W, 400nm TaSi2, 100nm Ti, and 300nm Pt are sequentially grown on the lower mesa of the tilted mesa structure, followed by rapid thermal annealing in a vacuum at 800℃ for 10s to form a P-type ohmic contact metal 6. Figure 3i As shown.

[0082] S10. Using magnetron sputtering, 100 nm Ti and 300 nm Pt are sequentially grown on P-type and N-type ohmic contact metals, respectively, and then rapidly thermally annealed in vacuum at 800°C for 10 s to form a diffusion barrier layer 9. Figure 3j As shown.

[0083] S11. Using photolithography, electron beam evaporation, etching, and magnetron sputtering, 20 nm TaSi2, 100 nm Pt, and 1 μm Au are sequentially grown on the diffusion barrier layer, and then annealed in Ar at 700 °C for 30 minutes to form the metal Pad8. Figure 3k As shown.

[0084] Thus, the fabrication of the high-temperature pin ultraviolet detector was completed. In the fabricated high-temperature pin ultraviolet detector, the n-type 4H-SiC ohmic contact Ti / TaSi2 / Ti / Pt and the Ti / Pt diffusion barrier layer are highly effective in preventing Au and O migration into the active epitaxial layer. Ni is used to lower the annealing temperature required for the formation of the p-type ohmic contact, and the metallic W can bind C to react and dissipate the free C generated by the Ni-based ohmic contact. This allows the 4H-SiC sensor and electronic device to operate reliably for a certain period of time even at a high temperature of 800℃.

[0085] It should be noted that the CVD process, photoresist reflow technology, inductively coupled plasma etching process, thermal oxidation process, photolithography, etching and magnetron sputtering process, annealing process, electron beam evaporation process, and etching process involved in the fabrication of high-temperature pin ultraviolet detectors are all existing mature processes. This embodiment only provides a simple description, and the detailed implementation process can be found by referring to the existing related technologies.

[0086] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," 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 invention 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 invention.

[0087] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0089] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0090] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A high-temperature pin ultraviolet detector, characterized in that, It includes a 4H-SiC substrate (1), a 4H-SiC epitaxial layer (2), a 4H-SiC absorber layer (3), a 4H-SiC contact layer (4), a passivation layer (5), a P-type ohmic contact metal (6), an N-type ohmic contact metal (7), a metal pad (8), and a diffusion barrier layer (9). The 4H-SiC substrate (1), the 4H-SiC epitaxial layer (2), the 4H-SiC absorber layer (3) and the 4H-SiC contact layer (4) are stacked from bottom to top; The 4H-SiC contact layer (4), the 4H-SiC absorber layer (3), and the 4H-SiC epitaxial layer (2) are etched to form an angled mesa structure on both sides; wherein, the upper surface of the 4H-SiC contact layer (4) forms the upper mesa of the angled mesa structure, and the sidewalls of the 4H-SiC contact layer (4), the sidewalls of the 4H-SiC absorber layer (3), and part of the sidewalls of the 4H-SiC epitaxial layer (2) together form the inclined sidewalls of the angled mesa structure; the upper surfaces on both sides of the 4H-SiC epitaxial layer (2) form the lower mesa of the angled mesa structure; The 4H-SiC contact layer (4) has several inverted trapezoidal trenches etched in the middle. The several inverted trapezoidal trenches extend downward from the upper surface of the 4H-SiC contact layer (4) to the interior of the 4H-SiC contact layer (4). The passivation layer (5) covers the entire upper surface of the device; The P-type ohmic contact metal (6) is disposed on the lower platform of the tilted platform structure, comprising Ni / W / TaSi2 / Ti / Pt stacked sequentially; The N-type ohmic contact metal (7) is disposed on the upper platform of the tilted platform structure, comprising Ti / TaSi2 / Ti / Pt stacked sequentially; The metal pad (8) is disposed above the P-type ohmic contact metal (6) and the N-type ohmic contact metal (7); A diffusion barrier layer (9) is further provided between the metal Pad (8) and the P-type ohmic contact metal (6), and between the metal Pad (8) and the N-type ohmic contact metal (7), wherein the diffusion barrier layer (9) comprises metal Ti / Pt.

2. The high-temperature pin ultraviolet detector according to claim 1, characterized in that, The 4H-SiC substrate (1) is n+ doped; The 4H-SiC epitaxial layer (2) is p+ doped with a doping concentration of 5×10⁻⁶. 18 -5.0×10 19 cm -3 The doping element is Al. The 4H-SiC absorber layer (3) is n-doped with a carrier concentration of 1.0 × 10⁻⁶. 15 -1.0×10 16 cm -3 ; The 4H-SiC contact layer (4) is n+ doped with a carrier concentration of 5.0 × 10⁻⁶. 18 -1.0×10 19 cm -3 .

3. The high-temperature pin ultraviolet detector according to claim 1, characterized in that, The inverted trapezoidal groove has a depth of 0.2-0.4 μm and a width of 1-2 μm.

4. A high-temperature pin ultraviolet detector according to claim 1, characterized in that, The passivation layer (5) is made of SiO2 / SiN x The composite layer has a thickness of 20-30 nm.

5. A high-temperature pin ultraviolet detector according to claim 1, characterized in that, The material of the metal Pad (8) is TaSi2 / Pt / Au.

6. A method for fabricating a high-temperature pin ultraviolet detector, characterized in that, The preparation method includes the following steps: A 4H-SiC epitaxial layer, a 4H-SiC absorber layer, and a 4H-SiC contact layer are sequentially formed on a 4H-SiC substrate. The 4H-SiC contact layer, the 4H-SiC absorber layer, and the 4H-SiC epitaxial layer are etched to form an angled mesa structure. The upper surface of the 4H-SiC contact layer forms the upper mesa of the angled mesa structure, and the sidewalls of the 4H-SiC contact layer, the 4H-SiC absorber layer, and a portion of the sidewalls of the 4H-SiC epitaxial layer together form the inclined sidewalls of the angled mesa structure. The upper surfaces on both sides of the 4H-SiC epitaxial layer form the lower mesa of the angled mesa structure. The middle position of the 4H-SiC contact layer is etched to form several inverted trapezoidal trenches; A passivation layer is formed on the entire sample surface; P-type ohmic contact metal and N-type ohmic contact metal are respectively fabricated on the lower and upper platforms of the tilted platform structure; wherein, the P-type ohmic contact metal comprises Ni / W / TaSi2 / Ti / Pt stacked sequentially, and the N-type ohmic contact metal comprises Ti / TaSi2 / Ti / Pt stacked sequentially. A diffusion barrier layer is formed on the P-type ohmic contact metal and the N-type ohmic contact metal; the diffusion barrier layer metal is Ti / Pt. A metal pad is formed on the diffusion barrier layer, thereby completing the device fabrication.

7. The method for fabricating a high-temperature pin ultraviolet detector according to claim 6, characterized in that, A 4H-SiC epitaxial layer, a 4H-SiC absorber layer, and a 4H-SiC contact layer are sequentially formed on a 4H-SiC substrate, specifically including: A 350 μm thick n+ type 4H-SiC substrate is provided; A 2 μm thick p+ type 4H-SiC epitaxial layer was epitaxially grown on the n+ type 4H-SiC substrate using conventional CVD process; An n-type 4H-SiC absorber layer with a thickness of 1 μm was epitaxially grown on the p+ type 4H-SiC epitaxial layer using CVD process; An n+ type 4H-SiC contact layer with a thickness of 0.5 μm was epitaxially grown on the n- type 4H-SiC absorber layer using a CVD process.

8. The method for fabricating a high-temperature pin ultraviolet detector according to claim 6, characterized in that, P-type ohmic contact metal and N-type ohmic contact metal are respectively fabricated on the lower and upper platforms of the tilted platform structure, specifically including: Using photolithography, etching, and magnetron sputtering processes, 100nm Ni, 30nm W, 400nm TaSi2, 100nm Ti, and 300nm Pt are sequentially grown on the lower mesa of the tilted mesa structure to form a P-type ohmic contact metal. Using photolithography, etching, and magnetron sputtering processes, 100nm Ti, 300nm TaSi2, 100nm Ti, and 300nm Pt are sequentially grown on the upper mesa of the tilted mesa structure to form an N-type ohmic contact metal.

9. The method for fabricating a high-temperature pin ultraviolet detector according to claim 6, characterized in that, A diffusion barrier layer is formed on the P-type ohmic contact metal and the N-type ohmic contact metal; comprising: Using magnetron sputtering technology, 100 nm Ti and 300 nm Pt are sequentially grown on the P-type ohmic contact metal and the N-type ohmic contact metal to form diffusion barrier layers.

10. The method for fabricating a high-temperature pin ultraviolet detector according to claim 6, characterized in that, Forming a metal pad on the diffusion barrier layer specifically includes: A metal Pad is formed by sequentially growing 20 nm TaSi2, 100 nm Pt, and 1 μm Au on the diffusion barrier layer.

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