Bonding tension enhanced terminal modulation type diamond nuclear detector and preparation method thereof

Abstract

The invention belongs to the technical field of semiconductors, and discloses a bonding-tension-enhanced terminal modulation type diamond nuclear detector and a preparation method thereof, and the bonding-tension-enhanced terminal modulation type diamond nuclear detector can give consideration to low-impedance ohmic contact and high bonding tension of the diamond nuclear detector at the same time. The bonding tension enhanced ohmic contact electrode is positioned in a first electrode region (the surface of the nitrogen terminal diamond) on the surface of the diamond; the high-work-function metal ohmic contact electrode is located in a second electrode area (the surface of the hydrogen terminal diamond) of the diamond surface and the surface of the bonding tension enhanced ohmic contact electrode; the insulating region (non-oxygen terminal diamond surface) is positioned in a non-electrode region of the diamond surface; the bonding tension enhanced ohmic contact electrode is a Ti / Pt / Au laminated layer, a contact interface between the bonding tension enhanced ohmic contact electrode and diamond is a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer, and the bonding tension enhanced ohmic contact electrode is formed by annealing a nitrogen terminal diamond surface and Ti in the Ti / Pt / Au laminated layer in a nitrogen atmosphere.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to a terminal modulation type diamond nuclear detector with enhanced bonding pull and its preparation method. Background Technology

[0002] Semiconductor nuclear detectors are electronic devices that utilize the ionization effect between radiation and semiconductor materials. They measure electrical signals generated by the transport of electron / hole pairs ionized within the semiconductor under an electric field. Compared to gas and scintillator nuclear detectors, semiconductor nuclear detectors have gained widespread application due to their advantages such as small size, high resolution, and fast response speed.

[0003] In applications requiring high reliability, such as nuclear power generation, space exploration, geological exploration, and medical radiotherapy, device failure and performance degradation can lead to serious application accidents. Therefore, it is essential to ensure that nuclear detectors possess strong operational reliability, preventing electrical connection failures. Simultaneously, the devices should also exhibit good detection performance, long-term operational stability, and tolerance to environmental changes. This necessitates the development of novel nuclear detectors that combine high electrical connection reliability, good ohmic contact characteristics, strong radiation resistance, and tolerance to extreme environments.

[0004] In enhancing the electrical connection reliability of nuclear detectors, it is typically necessary to improve the adhesion of the electrodes on the device surface to increase the wire bonding pull strength during subsequent packaging. Ohmic contacts require the electrodes to have non-rectifying characteristics and very low contact impedance after contact with the detector material, thereby improving response sensitivity and linearity. Radiation resistance and tolerance to extreme environments are largely determined by the intrinsic properties of the detector material. Traditional semiconductor nuclear detectors such as silicon, germanium, and gallium arsenide have poor radiation resistance, poor temperature characteristics, and slow response speeds, making them difficult to adapt to extreme service conditions. While third-generation semiconductor nuclear detectors such as silicon carbide and gallium nitride possess better characteristics, their radiation resistance, temperature tolerance, and performance stability are still insufficient to fully support the aforementioned application scenarios. Diamond is a type of ultra-wide bandgap semiconductor. It has a wider bandgap (5.5 eV) and extremely high intrinsic resistivity (10⁻⁶ eV). 12 ~10 16 Ω·cm), high carrier mobility (4500cm) 2 Diamond's excellent properties, such as its high thermal conductivity (2200 W / m·K) and low thermal conductivity (V·s), mean it possesses stronger radiation resistance, extremely low volume leakage current, and high time response speed. Compared to traditional semiconductor nuclear detectors, nuclear detectors made of diamond are suitable for detection in extreme service scenarios such as high radiation and wide temperature ranges. However, diamond nuclear detectors still face the following significant challenges in extreme service scenarios: On the one hand, diamond nuclear detectors suffer from poor adhesion between the surface and electrodes, resulting in low pull-out force after bonding with conventional silicon-aluminum wires and gold wires during encapsulation, severely impacting device reliability. Typically, a pull-out force of ≥3g after wire bonding is required for random vibration, acceleration, and other environmental physical experiments to ensure the packaging connections do not break, thus preventing overall device failure. However, due to the strong chemical inertness, extremely low surface energy, and high hardness of diamond, metal deposits on its surface are easily eroded by external forces, often resulting in a bond pull-out force of less than 3g, significantly affecting the electrical connection reliability of the device. On the other hand, for diamond nuclear detectors, achieving a good ohmic contact structure and improving electrode adhesion present a dilemma, making it difficult to simultaneously achieve low-impedance ohmic contact and high bond pull-out force.

[0005] In current technology, there are two common methods for forming ohmic contacts on diamond surfaces: The first method involves using conductive terminals such as hydrogen terminals to form an ohmic contact with a high work function metal (such as Au, Pd, etc.). Figure 1 As shown, the characteristic contact resistivity can be less than 10. -5 Ω·cm 2 The principle is to use band matching to reduce the contact barrier or form an ohmic contact without generating a significant rectified contact barrier. However, the conductive terminal surface cannot form a stable mechanical pull with the metal, resulting in poor metal adhesion and low wire bonding strength, often less than 1g. The second type uses a composite electrode structure, such as Figure 2 As shown, structures such as Ti / Au and Ti / Pt / Au are deposited on the diamond surface after cleaning with organic and inorganic solutions, followed by annealing in hydrogen or a vacuum (not absolute vacuum). Although the electrode adhesion of this method is higher than that of the first method, the contact impedance of the multilayer metal structure in this method is relatively high. Moreover, Ti will form an insulating layer such as TiO2 with oxygen adsorbates that are easily present on the diamond surface and oxygen in the ambient atmosphere, which will further increase the contact resistance and even lead to failure due to the formation of an insulating layer. Typically, the contact impedance of this structure is higher than that of the ohmic contact structure on the surface of the conductive terminal diamond, which reduces the detection performance of the diamond nuclear detector.

[0006] These issues limit the performance and reliability of current diamond nuclear detectors under extreme service conditions, hindering their further application. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention provides a terminal modulation type diamond nuclear detector with enhanced bonding pull and its fabrication method.

[0008] The technical problem to be solved by this invention is achieved through the following technical solution: A terminal modulation diamond nucleus detector with enhanced bond pull, comprising: Diamond; A bonding pull-enhanced ohmic contact electrode is located in the first electrode region of the diamond surface; the diamond surface of the first electrode region is a nitrogen-terminated diamond surface; the bonding pull-enhanced ohmic contact electrode is a Ti / Pt / Au stack; the contact interface between the nitrogen-terminated diamond surface and the Ti / Pt / Au stack is a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer; the TiC-TiN-TiCN interface layer or the TiC-TiN-TiC interface layer is formed by annealing the nitrogen-terminated diamond surface and the Ti in the Ti / Pt / Au stack under a nitrogen atmosphere. A high work function metal ohmic contact electrode is located in the second electrode region on the diamond surface and on the surface of the bonding pull-enhanced ohmic contact electrode; the diamond surface of the second electrode region is a hydrogen-terminated diamond surface. An insulating region located in the non-electrode area of ​​the diamond surface; the diamond surface of the insulating region is an oxygen-terminated diamond surface.

[0009] Optionally, the diamond core detector has a planar structure or a vertical structure.

[0010] Optionally, in the Ti / Pt / Au stack, the thickness of Ti is 20-30 nm, the thickness of Pt is 20-30 nm, and the thickness of Au is 300-500 nm.

[0011] Optionally, the non-oxygen-terminated diamond surface is a nitrogen-terminated diamond surface with CN bonds or a fluorine-terminated diamond surface with CF bonds.

[0012] This invention also provides a method for fabricating a terminal modulation diamond nuclear detector with enhanced bonding pull, comprising: Step 1: Clean the diamond and remove adsorbents and residual impurities from its surface; Step 2: Form a nitrogen-terminated diamond surface on the diamond surface; Step 3: Select a first electrode region on the nitrogen-terminated diamond surface and deposit a Ti / Pt / Au stack in the first electrode region; Step 4: Annealing is performed in a nitrogen atmosphere to form a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer at the contact interface between the nitrogen-terminated diamond surface in the first electrode region and the Ti / Pt / Au stack, thereby obtaining a bond pull-enhanced ohmic contact electrode. Step 5: Form a hydrogen-terminated diamond surface in the area of ​​the diamond surface not covered by the bonding pull-enhanced ohmic contact electrode; Step 6: Select a second electrode region on the surface of the hydrogen-terminated diamond, and deposit a high work function metal on the second electrode region and the surface of the bonding pull-enhanced ohmic contact electrode to form a high work function metal ohmic contact electrode; Step 7: Form an oxygen-free terminal diamond surface in the non-electrode area of ​​the diamond surface that is not covered by the bonding pull-enhanced ohmic contact electrode and the high work function metal ohmic contact electrode, as an insulating area.

[0013] Optionally, in step 1, removing adsorbates and residual impurities from the diamond surface includes: performing argon plasma etching on the diamond surface to activate the diamond surface and remove adsorbates and residual impurities from the diamond surface.

[0014] Optionally, step 3 specifically includes: selecting a first electrode region on the nitrogen-terminated diamond surface and fabricating a hard mask, and depositing a Ti / Pt / Au stack in the first electrode region not covered by the hard mask.

[0015] Optionally, step 3 specifically includes: photolithographically etching a first electrode region on the nitrogen-terminated diamond surface, and depositing a Ti / Pt / Au stack in the first electrode region.

[0016] Optionally, the annealing temperature during the annealing process in step 4 is 800-950℃.

[0017] Optionally, the annealing time in step 4 is 3-5 minutes.

[0018] In the bonding pull-enhanced terminal modulation diamond nuclear detector provided by this invention, a Ti / Pt / Au stack is deposited on the surface of a nitrogen-terminated diamond and annealed in a nitrogen atmosphere. This forms a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer (hereinafter referred to as the interface layer) at the contact interface between the nitrogen-terminated diamond surface and the Ti / Pt / Au stack. The beneficial effects are as follows: (1) Nitrogen terminal is non-oxygen terminal, so the Ti in the Ti / Pt / Au stack and the contact interface of the nitrogen terminal diamond surface will not form a TiO2 insulating layer, which overcomes the problem that the existing composite electrode structure has a certain bonding pull but the ohmic contact impedance is too large or even fails.

[0019] (2) In the interface layer, TiN and TiCN have the characteristic of low internal stress. High internal stress can easily lead to electrode cracking or peeling, while lower internal stress is beneficial to improve its adhesion to the diamond surface. At the same time, the hardness, wear resistance and corrosion resistance of the interface layer are better than those of the single TiC structure. Thus, when the bonding pull-enhanced ohmic contact electrode is used as the bonding area of ​​the packaging lead, the pull will be further enhanced, and it will have better electrode adhesion, further enhancing the electrical connection reliability of the device.

[0020] (3) The interface layer is not simply TiC with poor conductivity, but contains TiN (or TiCN) with better conductivity. Since TiN is a material with better conductivity than TiC, the interface layer combines the strong adhesion of TiC and the good conductivity of TiN. Therefore, compared with the two existing schemes for forming ohmic contacts on diamond surfaces, the diamond nuclear detector proposed in this invention can simultaneously have the advantages of low impedance ohmic contacts and high bonding pull, and can better meet the high performance requirements and operational reliability under extreme service conditions. Attached Figure Description

[0021] Figure 1 A top view and a cross-sectional view of the bonding of a diamond nuclear detector with an existing hydrogen terminal structure; Figure 2 This is a top view of the structure and a cross-sectional view of the bonding of a diamond nuclear detector with an existing multilayer composite electrode structure. Figure 3 The effect diagram after performing step 2 in the fabrication method of the bonding pull-enhanced terminal modulation diamond nuclear detector provided by the present invention; Figure 4 The effect diagram after performing step 3 in the fabrication method of the bonding pull-enhanced terminal modulation diamond nuclear detector provided by the present invention; Figure 5 The effect diagram after performing step 5 in the fabrication method of the bonding pull-enhanced terminal modulation diamond nuclear detector provided by the present invention; Figure 6 The effect diagram after performing step 6 in the fabrication method of the bonding pull-enhanced terminal modulation diamond nuclear detector provided by the present invention; Figure 7 A schematic diagram of a vertically structured terminal modulation diamond nuclear detector with enhanced bonding pull force, provided by the present invention; Figure 8 A schematic diagram of a horizontally structured terminal modulation diamond nuclear detector with enhanced bonding pull force, provided by the present invention. Figure 9A top view and a cross-sectional view of the bonding situation of a terminal modulation type diamond nuclear detector with enhanced bonding pull of a vertical structure provided by the present invention; Figure 10 A schematic diagram of electrode bonding for a terminal modulation diamond nuclear detector with enhanced bonding pull provided by the present invention; Figure 11 The diagram shows the wire bonding pull force test results and contact resistance test results of a terminal modulation diamond nuclear detector with enhanced bonding pull force provided by the present invention.

[0022] Figure label: 1. Diamond; 2. Bond pull-enhanced ohmic contact electrode; 3. High work function metal ohmic contact electrode; 4. Insulating region; a. Nitrogen-terminated diamond surface; b. Hydrogen-terminated diamond surface. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0024] This invention provides a terminal modulation type diamond core detector with enhanced bond pull force. By designing different types of terminal and electrode structures in different sections of the diamond core detector, it simultaneously possesses the advantages of low-impedance ohmic contact and high bond pull force, thus better meeting the high-performance requirements and operational reliability under extreme service conditions. See also Figure 7 and Figure 8 As shown, the diamond nuclear detector provided by the present invention includes: a diamond 1, a bonding pull-enhanced ohmic contact electrode 2, a high work function metal ohmic contact electrode 3, and an insulating region 4.

[0025] In this design, the bond-strength reinforced ohmic contact electrode 2 is located in the first electrode region on the surface of diamond 1. The diamond surface in this first electrode region is a nitrogen-terminated diamond surface a, and the bond-strength reinforced ohmic contact electrode 2 is a Ti / Pt / Au stack. The contact interface between the nitrogen-terminated diamond surface a and the Ti / Pt / Au stack is a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer. This interface layer is formed by annealing the nitrogen-terminated diamond surface a and the Ti in the Ti / Pt / Au stack. Thus, a TiC-TiN-TiCN / Ti / Pt / Au ohmic contact structure or a TiC-TiN-TiC / Pt / Au ohmic contact structure (e.g., ...) is actually formed between the bond-strength reinforced ohmic contact electrode 2 and diamond 1. Figure 10 ), used as the wire bonding region for diamond core detectors, such as Figure 9 As shown.

[0026] Ti is a transition metal that can form carbides with carbon. The TiC generated by the contact between the nitrogen-terminated diamond surface and Ti in the Ti / Pt / Au stack can enhance the electrode adhesion. Meanwhile, Pt in the Ti / Pt / Au stack can prevent Ti from diffusing towards Au, thereby inhibiting the oxidation of Ti after precipitation on the Au surface. Au in the Ti / Pt / Au stack can prevent the oxidation of the ohmic contact electrode 2 surface due to the enhanced bonding pull, and at the same time facilitate wire bonding to form an ohmic contact.

[0027] The high work function metal ohmic contact electrode 3 is located on the surface of the diamond 1 in the second electrode region and on the surface of the bond pull-enhanced ohmic contact electrode 2. It is a low-impedance ohmic contact electrode. The diamond surface in the second electrode region is the hydrogen-terminated diamond surface b. The area containing the second electrode region and the bond pull-enhanced ohmic contact electrode 2 constitutes the main detection area of ​​the diamond nuclear detector. The high work function metal ohmic contact electrode 3 can be formed using high work function metals such as Au, Pd / Au, or Pt / Au.

[0028] Insulating region 4 is located in the non-electrode area of ​​the diamond 1 surface. It is used to suppress surface leakage and prevent lateral oxygen diffusion from oxidizing the Ti metal and increasing contact resistance. It can be understood that the non-electrode area refers to the area on the diamond 1 surface other than the first and second electrode areas. The diamond surface of insulating region 4 is a non-oxygen-terminated diamond surface. This non-oxygen-terminated diamond surface is either a nitrogen-terminated diamond surface with CN bonds or a fluorine-terminated diamond surface with CF bonds.

[0029] In this invention, the bond pull-enhanced ohmic contact electrode 2 is primarily responsible for the mechanical strength of the bonding, while the high work function metal ohmic contact electrode 3 is primarily responsible for achieving efficient detection. Furthermore, the insulating region 4 employs an oxygen-free termination, which not only suppresses surface leakage but also prevents lateral oxygen diffusion, thereby protecting the electrical properties of the TiC-TiN-TiCN or TiC-TiN-TiC interface layer. Thus, the bond pull-enhanced ohmic contact electrode 2, the high work function metal ohmic contact electrode 3, and the insulating region 4 work synergistically to achieve a diamond core detector that combines low-impedance ohmic contact with high bond pull strength.

[0030] In the bonding pull-enhanced terminal modulation diamond nuclear detector provided by this invention, a Ti / Pt / Au stack is deposited on the surface of a nitrogen-terminated diamond and annealed in a nitrogen atmosphere. This forms a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer at the contact interface between the nitrogen-terminated diamond surface and the Ti / Pt / Au stack. The beneficial effects are as follows: (1) Nitrogen terminal is non-oxygen terminal, so the Ti in the Ti / Pt / Au stack and the contact interface of the nitrogen terminal diamond surface will not form a TiO2 insulating layer, which overcomes the problem that the existing composite electrode structure has a certain bonding pull but the ohmic contact impedance is too large or even fails.

[0031] (2) In the interface layer, TiN and TiCN have the characteristic of low internal stress. High internal stress can easily lead to electrode cracking or peeling, while lower internal stress is beneficial to improve its adhesion to the diamond surface. At the same time, the hardness, wear resistance and corrosion resistance of the interface layer are better than those of the single TiC structure. Thus, when the bonding pull-enhanced ohmic contact electrode 2 is used as the bonding area of ​​the encapsulation lead, the pull will be further enhanced, and it will have better electrode adhesion, further enhancing the electrical connection reliability of the diamond core detector.

[0032] (3) The interface layer is not simply TiC with poor conductivity, but contains TiN (or TiCN) with better conductivity. Since TiN is a material with better conductivity than TiC, the interface layer combines the strong adhesion of TiC and the good conductivity of TiN. Therefore, compared with the two existing schemes for forming ohmic contacts on diamond surfaces, the diamond nuclear detector proposed in this invention can simultaneously have the advantages of low impedance ohmic contacts and high bonding pull, and can better meet the high performance requirements and operational reliability under extreme service conditions.

[0033] In this invention, the diamond nuclear detector can be a planar structure or a vertical structure. Figure 7 The image exemplifies a diamond core detector with a vertical structure; Figure 8 The image exemplarily illustrates a planar diamond core detector. Figure 8 This is a top view, therefore diamond 1 is not shown. Figure 8 As shown in the figure. It should be noted that planar structures, vertical structures, or other types of device structures formed by combining the electrode structures of this invention are all technical improvements extended from the concept of this invention.

[0034] Based on the same inventive concept, the present invention also provides a method for fabricating the above-mentioned bond pull-enhanced terminal modulation diamond nuclear detector, comprising the following steps: Step 1: Clean diamond 1 and remove adsorbents and residual impurities from its surface.

[0035] Specifically, diamond 1 is cleaned, and then argon plasma etching is used on the surface of diamond 1 to activate the surface of diamond 1 and remove surface adsorbates and residual impurities.

[0036] For example, this step can be performed by etching the surface of diamond 1 using ICP (inductively coupled plasma), with argon as the working gas, RF power of 80-120W, gas flow rate of 60-120sccm, and etching time of 2-5min.

[0037] The present invention does not limit the shape and thickness of diamond 1.

[0038] Step 2: Form nitrogen-terminated diamond surface a on the surface of diamond 1.

[0039] Specifically, nitrogen plasma treatment is used to treat the diamond surface, creating CN bonds on diamond 1 and generating nitrogen-terminated diamond surface a, such as... Figure 3 .

[0040] For example, this step can be performed by etching the surface of diamond 1 using ICP, with nitrogen as the working gas, RF power of 80-120W, gas flow rate of 60-120sccm, and etching time of 2-5min.

[0041] It is understandable that treating the surface of diamond 1 with nitrogen plasma further removes the CO bonds on the diamond surface and generates a nitrogen-terminated diamond surface a dominated by CN bonds on the surface of diamond 1. This can eliminate the formation of insulating TiO2 and provide the basis for the formation of TiN and TiCN in subsequent steps.

[0042] Step 3: Select the first electrode region on the nitrogen-terminated diamond surface (a), and deposit a Ti / Pt / Au stack in the first electrode region, as shown below. Figure 4 .

[0043] In one implementation, step 3 may specifically include: selecting a first electrode region on the nitrogen-terminated diamond surface a and fabricating a hard mask, then depositing a Ti / Pt / Au stack in the first electrode region not covered by the hard mask. In this implementation, a hard mask is used to block areas outside the first electrode region, allowing metal to be deposited directly in the selected first electrode region. This process is simple and suitable for large-scale production.

[0044] In another implementation, step 3 specifically includes: photolithographically etching a first electrode region on the nitrogen-terminated diamond surface a, and depositing a Ti / Pt / Au stack in the first electrode region.

[0045] For example, a double-layer photoresist process is used. The lower layer can be an SF series (negative photoresist), and the upper layer can be an AZ series (positive photoresist). After photolithography exposes the first electrode region, a Ti / Pt / Au stack is deposited in the first electrode region. After deposition, the remaining photoresist and its surface metal are stripped using a stripping solution. After stripping, annealing is performed in a nitrogen atmosphere at a temperature of 800-950℃ for 3-5 minutes.

[0046] In both of the above implementation methods, a Ti / Pt / Au metal of a certain thickness can be deposited in the first electrode region using a sputtering process to form a Ti / Pt / Au stack. For example, when depositing the Ti / Pt / Au stack, the thickness of the deposited Ti can be 20-30 nm, the thickness of the Pt can be 20-30 nm, and the thickness of the Au can be 300-500 nm.

[0047] It is understandable that if a vertical diamond core detector is to be fabricated, after selecting the first electrode region on one nitrogen-terminated diamond surface a and depositing a Ti / Pt / Au stack, a Ti / Pt / Au stack of the same thickness is deposited on the corresponding region on the other nitrogen-terminated diamond surface a using the same process.

[0048] Step 4: Annealing is performed in a nitrogen atmosphere to form a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer at the contact interface between the nitrogen-terminated diamond surface a in the first electrode region and the Ti / Pt / Au stack, thereby obtaining the bonding pull-enhanced ohmic contact electrode 2, which serves as the lead bonding region during packaging.

[0049] Preferably, the annealing temperature in step 4 is 800-950℃, and the annealing time is 3-5 minutes.

[0050] In step 4, the device sample prepared in step 3 is subjected to high-temperature annealing in a nitrogen atmosphere, which allows Ti to react with the diamond surface to form a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer. This improves the adhesion between the metal electrode (bonding pull-enhanced ohmic contact electrode 2) and the diamond. At the same time, the nitrogen atmosphere can prevent the formation of TiO2, further reducing the contact resistance. Platinum (Pt) can prevent Ti diffused to the surface from forming TiO2, ensuring high conductivity while providing an ideal bonding interface for the upper metal layer (i.e., Au).

[0051] Step 5: Form a hydrogen-terminated diamond surface b in the area of ​​diamond 1 that is not covered by the bond pull-enhanced ohmic contact electrode 2, such as... Figure 5 .

[0052] Specifically, in a hydrogen plasma atmosphere, the area on the surface of diamond 1 that is not covered by the bonding pull-enhanced ohmic contact electrode 2 is processed into a hydrogen-terminated diamond surface b.

[0053] For example, MPCVD (microwave plasma chemical vapor deposition) is used to etch the surface of diamond 1 that is not covered by the bond pull-enhanced ohmic contact electrode 2 in a hydrogen atmosphere to form a hydrogen-terminated diamond surface b. The process parameters may include: temperature of 800-1000℃, time of 20-40min, hydrogen flow rate of 500-800sccm, and pressure of 100mbar.

[0054] In this step, hydrogen plasma enables the formation of CH bonds on the diamond surface, reducing the work function of the diamond surface to approximately 5 eV. This allows for the formation of good ohmic contact (characteristic contact resistivity less than 10) with high work function metals (work function > 5.1 eV). -5 Ω·cm 2 ).

[0055] Step 6: Select the second electrode region on the hydrogen-terminated diamond surface b, and deposit a high work function metal on the second electrode region and the surface of the bonding pull-enhanced ohmic contact electrode 2 to form a high work function metal ohmic contact electrode 3, as shown below. Figure 6 .

[0056] Specifically, a second electrode region is selected on the surface b of the hydrogen-terminated diamond using photolithography or hard masking. This region occupies most of the sensitive area of ​​the diamond nuclear detector. Then, a high work function metal such as Au, Pd / Au, or Pt / Au is deposited in the second electrode region using a sputtering process, with a deposition thickness of 390-410 nm, forming a low-impedance high work function metal ohmic contact electrode 3.

[0057] It is understandable that if a vertical diamond nuclear detector is to be fabricated, after selecting the second electrode region on one hydrogen-terminated diamond surface b and depositing a high work function metal, the same high work function metal of the same material and thickness is deposited on the corresponding region on the other hydrogen-terminated diamond surface b using the same process, thereby completing the fabrication of the high work function metal ohmic contact electrode 3.

[0058] Step 7: Form an oxygen-free terminal diamond surface on the non-electrode area of ​​diamond 1 that is not covered by the bonding pull-strength enhanced ohmic contact electrode 2 and the high work function metal ohmic contact electrode 3, as an insulating region 4, such as... Figure 7 .

[0059] Among them, the non-oxygen-terminated diamond surface can be a nitrogen-terminated diamond surface with CN bonds or a fluorine-terminated diamond surface with CF bonds.

[0060] Specifically, for nitrogen-terminated diamond surfaces: the upper and lower surfaces of the diamond were etched using ICP (inductively coupled plasma) with nitrogen as the working gas, an RF power of 80-120 W, a gas flow rate of 60-120 sccm, and an etching time of 2-5 min. For fluorine-terminated diamond surfaces: the upper and lower surfaces of the diamond were etched using ICP (inductively coupled plasma) with CF4 as the working gas, an RF power of 80-120 W, a gas flow rate of 60-120 sccm, and an etching time of 2-5 min. This completed the fabrication of the diamond nuclear detector.

[0061] In step 7, the oxygen-free terminal diamond surface is formed on the diamond surface and sides that are not covered by the electrode metal. The oxygen-free terminal diamond surface has extremely high insulation properties. As a surface passivation layer, it can suppress surface leakage and reduce dark current. This not only avoids the lateral diffusion of oxygen at the electrode edge to generate TiO2, which would lead to an increase in contact resistance, but also effectively reduces the dark current of the diamond detector and improves the response signal-to-noise ratio of the diamond detector.

[0062] The preparation method of this invention fundamentally solves the core contradiction of achieving both high bonding pull and low contact impedance in diamond nuclear detectors. Specifically, the method first forms a nitrogen-terminated diamond surface 'a' on the diamond surface, deposits a Ti / Pt / Au stack on this surface, and then performs high-temperature annealing in a nitrogen atmosphere, causing Ti to react with the diamond and the nitrogen in the nitrogen atmosphere to generate an interface layer. This process actively avoids the formation of TiO2, and thanks to the excellent conductivity and low internal stress of TiN / TiCN, the bonding region achieves both high bonding pull and low contact resistivity.

[0063] Furthermore, the preparation method of the present invention prepares a hydrogen-terminated diamond surface in the main detection region and deposits a high work function metal, which ensures that the main detection region of the device has low contact resistance, and guarantees better charge collection efficiency and signal linearity of the diamond nuclear detector, thereby solving the mechanical reliability problem without sacrificing electrical performance.

[0064] Furthermore, the preparation method of this invention treats the non-electrode region into an oxygen-free terminal insulating region, such as a nitrogen or fluorine terminal. This not only effectively suppresses surface leakage current and reduces dark current, but also prevents environmental oxygen from laterally diffusing into the Ti interface of the bonding region, structurally ensuring the long-term stability of the bonded reinforcement electrode.

[0065] In summary, the preparation method of this invention fundamentally solves the core contradiction of balancing high bonding pull and low contact impedance in diamond core detectors, providing a practical and feasible technological basis for the reliable application of diamond core detectors in extreme environments.

[0066] It is worth mentioning that the bonding pull force of hydrogen terminal detectors prepared in the prior art is less than 1g, and the bonding pull force of multilayer composite electrode structure detectors in the prior art is less than 6g. However, the diamond nuclear detector prepared using the method of this invention (Ti / Pt / Au stack with Ti thickness of 30nm, Pt thickness of 30nm, Au thickness of 350nm, and high work function metal ohmic contact electrode 3 thickness of 410nm, made of Au) has an average bonding pull force of 9.8g after encapsulation, which is significantly better than the prior art. Figure 11 As shown. Furthermore, the contact resistivity of the diamond nuclear detector prepared using the method of this invention was tested, and its contact resistivity reached 1.27 × 10⁻⁶. -6 Ω·cm 2 It possesses a contact resistivity comparable to existing hydrogen terminal structures, and is far lower than the contact resistivity of traditional multilayer composite electrode structure detectors (4.64 × 10⁻⁶). -3 Ω·cm 2 ),like Figure 11 As shown. Experimental results show that the diamond nuclear detector prepared using the method of the present invention has good radiation detection performance, which can effectively balance the high detection performance and high service reliability of nuclear detectors. Compared with traditional structures, it is more suitable for radiation measurement in extreme scenarios such as high reliability, wide temperature range, and strong radiation.

[0067] It should be noted that the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention.

[0068] 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 or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0069] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings and the disclosure in carrying out the claimed invention. In the description of the invention, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0070] 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.

[0071] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0072] 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.

[0073] 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 terminal modulation type diamond core detector with enhanced bonding pull, characterized in that, include: Diamond; A bonding pull-enhanced ohmic contact electrode located in the first electrode region of the diamond surface; the diamond surface of the first electrode region is a nitrogen-terminated diamond surface. The bonding pull-enhanced ohmic contact electrode is a Ti / Pt / Au stack; the contact interface between the nitrogen-terminated diamond surface and the Ti / Pt / Au stack is a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer; the TiC-TiN-TiCN interface layer or the TiC-TiN-TiC interface layer is formed by annealing the nitrogen-terminated diamond surface and the Ti in the Ti / Pt / Au stack under a nitrogen atmosphere; A high work function metal ohmic contact electrode is located in the second electrode region on the diamond surface and on the surface of the bonding pull-enhanced ohmic contact electrode; the diamond surface of the second electrode region is a hydrogen-terminated diamond surface. An insulating region located in the non-electrode area of ​​the diamond surface; the diamond surface of the insulating region is an oxygen-terminated diamond surface.

2. The terminal modulation type diamond core detector with enhanced bonding pull according to claim 1, characterized in that, The diamond core detector has a planar structure or a vertical structure.

3. The terminal modulation type diamond core detector with enhanced bonding pull according to claim 1, characterized in that, In the Ti / Pt / Au stack, the thickness of Ti is 20-30 nm, the thickness of Pt is 20-30 nm, and the thickness of Au is 300-500 nm.

4. The terminal modulation type diamond core detector with enhanced bonding pull according to claim 1, characterized in that, The non-oxygen-terminated diamond surface is either a nitrogen-terminated diamond surface with CN bonds or a fluorine-terminated diamond surface with CF bonds.

5. A method for fabricating a terminal modulation type diamond nuclear detector with enhanced bonding pull, characterized in that, include: Step 1: Clean the diamond and remove adsorbents and residual impurities from its surface; Step 2: Form a nitrogen-terminated diamond surface on the diamond surface; Step 3: Select a first electrode region on the nitrogen-terminated diamond surface and deposit a Ti / Pt / Au stack in the first electrode region; Step 4: Annealing is performed in a nitrogen atmosphere to form a TiC-TiN-TiCN interface layer or a TiC-TiN-TiC interface layer at the contact interface between the nitrogen-terminated diamond surface in the first electrode region and the Ti / Pt / Au stack, thereby obtaining a bond pull-enhanced ohmic contact electrode. Step 5: Form a hydrogen-terminated diamond surface in the area of ​​the diamond surface not covered by the bonding pull-enhanced ohmic contact electrode; Step 6: Select a second electrode region on the surface of the hydrogen-terminated diamond, and deposit a high work function metal on the second electrode region and the surface of the bonding pull-enhanced ohmic contact electrode to form a high work function metal ohmic contact electrode; Step 7: Form an oxygen-free terminal diamond surface in the non-electrode area of ​​the diamond surface that is not covered by the bonding pull-enhanced ohmic contact electrode and the high work function metal ohmic contact electrode, as an insulating area.

6. The preparation method according to claim 5, characterized in that, Step 1, removing adsorbates and residual impurities from the diamond surface, includes: performing argon plasma etching on the diamond surface to activate the diamond surface and remove adsorbates and residual impurities from the diamond surface.

7. The preparation method according to claim 5, characterized in that, Step 3 specifically includes: selecting a first electrode region on the nitrogen-terminated diamond surface and fabricating a hard mask, and depositing a Ti / Pt / Au stack in the first electrode region not covered by the hard mask.

8. The preparation method according to claim 5, characterized in that, Step 3 specifically includes: photolithographically etching a first electrode region on the nitrogen-terminated diamond surface, and depositing a Ti / Pt / Au stack in the first electrode region.

9. The preparation method according to claim 5, characterized in that, The annealing temperature during the annealing process in step 4 is 800-950℃.

10. The preparation method according to claim 9, characterized in that, The annealing time in step 4 is 3-5 minutes.

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