A method for fabricating a self-organized silicon-terminated diamond electrical conductor and device
By developing a method for fabricating self-organized silicon-terminated diamond conductivity and devices, the problems of conductivity stability in hydrogen-terminated diamond and the complexity of silicon-terminated diamond material preparation were solved, resulting in reduced costs, increased yield, and improved device performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIDIAN UNIV
- Filing Date
- 2023-05-17
- Publication Date
- 2026-07-31
AI Technical Summary
In the existing technology, the surface conductivity stability problem of hydrogen-terminated diamond limits its application in high-temperature, high-frequency, and high-power electronic devices, and the preparation process of silicon-terminated diamond materials is complex and has a low yield.
A method for fabricating self-organized silicon-terminated diamond conductivity and devices includes polishing and cleaning the surface of a diamond single crystal, depositing a SiO2 layer by PECVD, etching by RIE, growing a diamond epitaxial layer by MPCVD, and fabricating the source, drain, and gate by photolithography. The silicon-terminated region and the non-silicon-terminated region are formed by self-peeling, which simplifies the process steps and eliminates the need for cutting and grinding.
It reduces the processing cost of diamond single crystals, improves yield and utilization, simplifies the silicon terminal device fabrication process, provides a new device fabrication method, and improves breakdown voltage and device performance.
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Figure CN116525446B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor device fabrication, specifically relating to a method for fabricating a self-organized silicon-terminated diamond conductivity device. Background Technology
[0002] With the rise of ultra-wide bandgap semiconductor materials, diamond possesses a series of advantages, including a large bandgap, high breakdown field strength, high thermal conductivity, and high carrier mobility, earning it the title of the ultimate semiconductor material. It has enormous application potential in high-temperature, high-frequency, and high-power electronic devices. Hydrogen-terminated diamond has long been the mainstream choice for device fabrication, but the surface conductivity stability of hydrogen-terminated diamond has limited its development and application. In recent years, the emergence of silicon-terminated diamond has provided a new approach to solving this problem. However, the complex fabrication process and low yield of silicon-terminated diamond materials and devices have led to slow development. Summary of the Invention
[0003] To address the aforementioned problems in the prior art, this invention provides a method for fabricating self-organized silicon-terminated diamond conductivity devices. The technical problem to be solved by this invention is achieved through the following technical solution:
[0004] A method for fabricating self-organized silicon-terminated diamond conductivity devices, comprising the following steps:
[0005] The surface of the diamond single crystal is polished and cleaned to obtain the treated diamond single crystal;
[0006] A SiO2 layer was obtained by depositing a diamond single crystal treated with PECVD.
[0007] The SiO2 layer is photolithographically etched using a mask.
[0008] The patterned substrate is obtained by etching the SiO2 layer after photolithography using RIE.
[0009] A diamond single-crystal epitaxial layer is grown on a patterned substrate using an MPCVD device. During the cooling process, the grown diamond single-crystal epitaxial layer is made to exhibit stress non-uniformity to achieve self-peeling and form silicon-terminated and non-silicon-terminated regions on the lower surface of the peeled-off diamond single-crystal epitaxial layer.
[0010] Photolithography is performed on the silicon termination region to fabricate source and drain electrodes on both sides of the silicon termination region;
[0011] Photolithography and SiO2 deposition are performed on the silicon terminal region to form the gate dielectric;
[0012] Photolithography was performed on the deposited SiO2 region, and the gate was fabricated in the middle region of the gate dielectric using an electron beam evaporation device.
[0013] In one embodiment of the present invention, polishing and cleaning the surface of a diamond single crystal includes:
[0014] Cutting and polishing diamond single crystals can achieve a surface roughness of 0-10 nm.
[0015] The polished diamond single crystal was subjected to inorganic and organic cleaning, rinsed in flowing deionized water, and then dried with a nitrogen gun.
[0016] In one embodiment of the present invention, inorganic cleaning includes:
[0017] The polished diamond single crystal was cleaned using a heated mixture of sulfuric acid and nitric acid.
[0018] In one embodiment of the present invention, organic cleaning includes:
[0019] Ultrasonic cleaning with acetone, ethanol or isopropanol and deionized water for 0-30 minutes respectively.
[0020] In one embodiment of the present invention, RIE etching of the photolithographically etched SiO2 layer includes:
[0021] A CHF3 / O2 gas mixture was introduced into the RIE reactive ion etching equipment, and the radio frequency and inductively coupled plasma powers were set to 50-200W and 50-500W, respectively, before etching was performed.
[0022] In one embodiment of the present invention, a diamond single-crystal epitaxial layer is grown on the patterned substrate using an MPCVD device, including:
[0023] In MPCVD, the temperature is set to 800–1200℃, the pressure to 100–200 mbar, the H2 flow rate to 200–600 sccm, the CH4 flow rate to 0–100 sccm, and the N2 flow rate to 0.01–1 sccm, so that diamond single crystals are laterally heteroepitaxially grown on the patterned substrate.
[0024] In one embodiment of the present invention, during the cooling process, a method is used to induce stress non-uniformity in the grown diamond single-crystal epitaxial layer to achieve self-peeling, including:
[0025] During the cooling process, the thickness of the transverse heteroepitaxially grown diamond single crystal reaches 100um to 600um.
[0026] In one embodiment of the present invention, the non-silicon termination region is used to form an isolation region between devices.
[0027] In one embodiment of the present invention, photolithography is performed on the silicon termination region to fabricate source and drain electrodes on both sides of the silicon termination region, including:
[0028] Photolithography is applied to the silicon terminal region. Ti / Au 0-100nm is deposited on both sides of the silicon terminal region using electron beam evaporation. Then, excess photoresist is washed away, and after annealing for 30 minutes, ohmic contacts are formed to form the source and drain electrodes, which are located within the silicon terminal region.
[0029] In one embodiment of the present invention, photolithography is performed on the silicon terminal region, SiO2 is deposited to form a gate dielectric, and photolithography is performed on the deposited SiO2 region. An electron beam evaporation apparatus is used to fabricate a gate electrode in the middle of the gate dielectric, comprising:
[0030] A photolithographic mask is applied to the silicon terminal region. SiO2 is deposited in the middle and near-middle source and drain regions of the silicon terminal region. Excess photoresist is washed away to form a gate dielectric. In the middle region of the gate dielectric, Ti / Au is deposited as the gate electrode using an electron beam evaporation device to form a Schottky contact. Excess photoresist is then washed away to obtain a complete silicon terminal device.
[0031] The beneficial effects of this invention are:
[0032] 1. The self-exfoliating diamond single crystal prepared by the embodiments of the present invention eliminates the need for subsequent cutting and grinding, thereby reducing the processing and preparation cost of diamond single crystal and improving the yield and utilization rate.
[0033] 2. The stripped diamond single crystal contains a silicon terminal region, eliminating the need for a separate silicon terminal surface conductivity fabrication process. It can be directly used as a substrate for silicon terminal devices, providing a new method for silicon terminal device fabrication, simplifying the silicon terminal device fabrication process, and ensuring compatibility with existing processes.
[0034] 3. The stripped diamond single crystal can be used as an isolation region for device fabrication in the part without silicon termination. When fabricating silicon-terminated devices, device isolation is not required, which simplifies the process steps.
[0035] 4. The source and drain portions contain some SiO2, which can reduce the electric field and increase the breakdown voltage. Attached Figure Description
[0036] Figure 1 This is a schematic flowchart illustrating a method for fabricating a self-organized silicon-terminated diamond conductivity device according to an embodiment of the present invention.
[0037] Figures 2(a) to 2(g) The diagram shows the specific process steps of the fabrication method of self-organized silicon-terminated diamond conductivity and device provided in the embodiments of the present invention.
[0038] Figure 3 This is a plan view of the silicon terminal device provided in an embodiment of the present invention. Detailed Implementation
[0039] 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.
[0040] like Figure 1 As shown in the embodiment of the present invention, a method for fabricating a self-organized silicon-terminated diamond conductivity device includes the following steps:
[0041] S1, Polish and clean the surface of the diamond single crystal to obtain the treated diamond single crystal;
[0042] S2, the treated diamond single crystal is deposited using PECVD (Plasma Enhanced Chemical Vapor Deposition) to obtain a SiO2 layer;
[0043] S3, the SiO2 layer is photolithographically etched using a mask;
[0044] S4. The SiO2 layer after photolithography is etched using RIE (Reactive Ion Etching) to obtain a patterned substrate;
[0045] S5. A diamond single-crystal epitaxial layer is grown on the patterned substrate using MPCVD (Microwave Plasma Chemical Vapor Deposition). During the cooling process, the grown diamond single-crystal epitaxial layer is made to have uneven stress to achieve self-peeling and form silicon-terminated and non-silicon-terminated regions on the lower surface of the peeled diamond single-crystal epitaxial layer.
[0046] S6, perform photolithography on the silicon terminal region to prepare source and drain electrodes on both sides of the silicon terminal region;
[0047] S7, Photolithography is performed on the silicon terminal region to deposit SiO2 to form a gate dielectric;
[0048] S8, perform photolithography on the deposited SiO2 region, and use an electron beam evaporation device to fabricate the gate in the middle region of the gate dielectric.
[0049] In one optional embodiment of S1, polishing and cleaning the surface of the diamond single crystal includes:
[0050] Cutting and polishing diamond single crystals can achieve a surface roughness of 0-10 nm; of course, the surface roughness requirement can be set as needed, and no specific limitation is made here.
[0051] The polished diamond single crystal was subjected to inorganic and organic cleaning, rinsed in flowing deionized water, and then dried with a nitrogen gun.
[0052] In one optional embodiment, inorganic cleaning includes cleaning the polished diamond single crystal with a heated mixed solution of sulfuric acid and nitric acid.
[0053] In one optional embodiment, organic cleaning includes ultrasonic cleaning with acetone, ethanol or isopropanol and deionized water for 0 to 30 minutes respectively.
[0054] In the above methods, either ethanol or isopropanol can be selected. Of course, the cleaning time can also be set as needed, and there are no restrictions here.
[0055] For S2, please refer to the relevant technology for the PECVD method, which will not be described here. The thickness of the SiO2 layer obtained by depositing the treated diamond single crystal by PECVD can be determined as needed. For example, in one optional embodiment, a SiO2 layer with a thickness of 0 to 600 nm can be obtained by PECVD deposition, as shown in Figure 2(a).
[0056] For S3, during photolithography, a 1-10µm thick photoresist is added by spin coating, and the excess photoresist is removed by photolithography and development.
[0057] For S4, in one optional implementation, the SiO2 layer after photolithography is etched using RIE, including:
[0058] A CHF3 / O2 (trifluoromethane / oxygen) gas mixture was introduced into the RIE (Reactive Ion Etching) equipment, and the radio frequency (RF) and inductively coupled plasma (ICP) powers were set to 50–200 W and 50–500 W, respectively, before etching. The desired pattern was obtained by etching the SiO2 layer. Excess photoresist was then washed away, resulting in the desired patterned substrate shown in Figure 2(b). It should be noted that the SiO2 pattern after photolithography and etching in Figure 2(b) is merely an example for illustrative purposes and should not be construed as limiting the scope of the invention.
[0059] For S5, a diamond single-crystal epitaxial layer is grown on the patterned substrate using an MPCVD device, including:
[0060] In MPCVD, the temperature is set to 800℃~1200℃, the pressure to 100~200mbar, the H2 flow rate to 200~600sccm, the CH4 flow rate to 0~100sccm, and the N2 flow rate to 0.01~1sccm, so that diamond single crystals are laterally heteroepitaxially grown on the patterned substrate.
[0061] In one optional embodiment, during the cooling process, the method of causing stress non-uniformity in the grown diamond single-crystal epitaxial layer to achieve self-exfoliation includes:
[0062] During the cooling process, the thickness of the transverse heteroepitaxially grown diamond single crystal reaches 100um to 600um.
[0063] In MPCVD, reaction conditions are set within a preset range for lateral heteroepitaxial growth of single crystals. When the thickness reaches 100µm to 600µm, the crystals self-peel due to stress inhomogeneity, as shown in Figure 2(c), eliminating the need for traditional cutting processes. The lower surface of the peeled diamond single crystal epitaxial layer forms a silicon-terminated region and a non-silicon-terminated region, as shown in Figure 2(d). The non-silicon-terminated region is used to create isolation areas between devices. Therefore, in this embodiment of the invention, device isolation is not required when fabricating silicon-terminated devices, simplifying the process steps.
[0064] For S6, source and drain electrodes are fabricated on both sides of the silicon termination region, as shown in Figure 2(e), including:
[0065] A photolithographic mask is applied to the silicon terminal region, and Ti / Au 0-100nm is deposited on both sides of the silicon terminal region using electron beam evaporation. Then, excess photoresist is washed away, and after annealing for 30 minutes, ohmic contacts are formed to form the source and drain, which are located within the silicon terminal region.
[0066] For S7, photolithography is performed on the silicon terminal region to deposit SiO2 to form a gate dielectric, as shown in Figure 2(f). After the deposited SiO2 is washed to remove excess photoresist, it serves as the gate dielectric. Part of the gate dielectric contacts the source and drain electrodes, which can improve the breakdown voltage.
[0067] For S8, photolithography is performed on the deposited SiO2 region, and the gate electrode is fabricated in the middle region of the gate dielectric using an electron beam evaporation apparatus, as shown in Figure 2(g).
[0068] Ti / Au is deposited as the gate electrode in the middle region of the gate dielectric using an electron beam evaporation device to form a Schottky contact. Excess photoresist is then washed away to obtain a complete silicon-terminated device. The planar view of the silicon-terminated device is shown below. Figure 3 As shown.
[0069] This invention employs microwave plasma chemical vapor deposition (MPCVD) to epitaxially grow silicon-terminated regions on a patterned single-crystal substrate. This yields regions containing silicon terminals, while the non-silicon-terminated regions serve as device isolation areas. Compared to traditional silicon-terminated diamond material and device fabrication, this method eliminates the need for silicon terminal surface conductivity fabrication and device isolation steps, providing a novel fabrication method for silicon-terminated materials and devices. Furthermore, the self-peeling method eliminates the need for cutting and grinding the epitaxial single crystal, allowing it to be directly used as the device substrate. This reduces cost and time, improves yield, and ensures compatibility with existing processes.
[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.
[0071] 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 method of fabricating a self-organized silicon-terminated diamond electrical conductor and device, the method comprising the steps of: include: The surface of the diamond single crystal is polished and cleaned to obtain the treated diamond single crystal; A SiO2 layer was obtained by depositing the treated diamond single crystal using PECVD. The SiO2 layer is photolithographically etched using a mask. The patterned substrate is obtained by etching the SiO2 layer after photolithography using RIE. A diamond single-crystal epitaxial layer is grown on the patterned substrate using an MPCVD equipment. During the cooling process, the grown diamond single-crystal epitaxial layer is made to exhibit stress non-uniformity to achieve self-peeling and form silicon-terminated and non-silicon-terminated regions on the lower surface of the peeled-off diamond single-crystal epitaxial layer. Photolithography is performed on the silicon terminal region to fabricate source and drain electrodes on both sides of the silicon terminal region; Photolithography and SiO2 deposition are performed on the silicon terminal region to form a gate dielectric. The deposited SiO2 region is photolithographically etched, and the gate is fabricated in the middle region of the gate dielectric using an electron beam evaporation apparatus.
2. The method for fabricating self-organized silicon-terminated diamond conductivity and devices according to claim 1, characterized in that, The polishing and cleaning of the surface of the diamond single crystal includes: Cutting and polishing diamond single crystals can achieve a surface roughness of 0-10 nm. The polished diamond single crystal was subjected to inorganic and organic cleaning, rinsed in flowing deionized water, and then dried with a nitrogen gun.
3. The method for preparing self-organized silicon-terminated diamond conductivity and devices according to claim 2, characterized in that, The inorganic cleaning includes: The polished diamond single crystal was cleaned using a heated mixture of sulfuric acid and nitric acid.
4. The method of claim 2, wherein the method further comprises the step of: The organic cleaning includes: Ultrasonic cleaning with acetone, ethanol or isopropanol and deionized water for 0-30 minutes respectively.
5. The method for fabricating self-organized silicon-terminated diamond conductivity and devices according to claim 1, characterized in that, The etching of the SiO2 layer after photolithography using RIE includes: A CHF3 / O2 gas mixture was introduced into the RIE reactive ion etching equipment, and the radio frequency and inductively coupled plasma powers were set to 50-200W and 50-500W, respectively, before etching was performed.
6. The method for fabricating self-organized silicon-terminated diamond conductivity and devices according to claim 1, characterized in that, The growth of a diamond single-crystal epitaxial layer on the patterned substrate using an MPCVD device includes: In MPCVD, the temperature is set to 800–1200℃, the pressure to 100–200 mbar, the H2 flow rate to 200–600 sccm, the CH4 flow rate to 0–100 sccm, and the N2 flow rate to 0.01–1 sccm, so that diamond single crystals are laterally heteroepitaxially grown on the patterned substrate.
7. The method for fabricating self-organized silicon-terminated diamond conductivity and devices according to claim 6, characterized in that, During the cooling process, methods to induce stress inhomogeneity in the grown diamond single-crystal epitaxial layer to achieve self-exfoliation include: During the cooling process, the thickness of the transverse heteroepitaxially grown diamond single crystal reaches 100um to 600um.
8. The method for fabricating self-organized silicon-terminated diamond conductivity and devices according to claim 1, characterized in that, The non-silicon terminal area is used to form an isolation area between devices.
9. The method for fabricating self-organized silicon-terminated diamond conductivity and devices according to claim 1, characterized in that, The step of photolithography on the silicon termination region to fabricate source and drain electrodes on both sides of the silicon termination region includes: A photolithographic mask is applied to the silicon terminal region, and Ti / Au 0-100nm is deposited on both sides of the silicon terminal region using electron beam evaporation. Then, excess photoresist is washed away, and after annealing for 30 minutes, ohmic contacts are formed to form the source and drain, which are located within the silicon terminal region.
10. The method of claim 1, wherein the self-organized silicon-terminated diamond electrical conductor and device is prepared by the steps of: The step of photolithography on the silicon terminal region, deposition of SiO2 to form a gate dielectric, and photolithography on the deposited SiO2 region, followed by fabrication of a gate electrode in the middle of the gate dielectric using an electron beam evaporation apparatus, includes: A photolithographic mask is applied to the silicon terminal region. SiO2 is deposited in the middle and near-middle source / drain regions of the silicon terminal region. Excess photoresist is washed away to form a gate dielectric. In the middle region of the gate dielectric, Ti / Au is deposited as a gate electrode using an electron beam evaporation device to form a Schottky contact. Excess photoresist is then washed away to obtain a complete silicon terminal device.