MOSFET device and preparation method thereof
The boron-nitrogen co-doped N-type diamond layer is prepared through the MPCVD process, which solves the problem of insufficient diamond n-type doping performance and improves the overall performance of MOSFET devices, making them suitable for high-frequency, high-power and high-temperature environments.
Patent Information
- Application Number
- CN202510901838.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2025-10-17
AI Technical Summary
In the prior art, n-type doping of diamond does not meet the requirements of practical applications in terms of electron concentration and electron mobility, which limits its widespread application in high-performance electronic devices.
The MPCVD process is used for boron and nitrogen co-doping to prepare the N-type diamond layer. By controlling the growth temperature, pressure, microwave power and gas ratio, the efficient co-doping of boron and nitrogen is ensured to form an N-type diamond film with high electrical properties.
It significantly improves the electron concentration and mobility of N-type diamond, enhances the voltage resistance of MOSFET devices, reduces leakage current, optimizes heat dissipation performance and stability, and is suitable for applications in high-frequency, high-power and high-temperature environments.
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Figure CN120812973A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of semiconductors, and particularly relates to a MOSFET device and a preparation method thereof. BACKGROUND
[0002] With the advent of the 5G era and the promotion of the "double carbon" strategy, electronic devices are accelerating towards high power, multi-band, high efficiency, small size, high reliability and low cost. However, the traditional first-generation semiconductor material silicon (Si) and the second-generation semiconductor material gallium arsenide (GaAs) have been unable to meet the increasingly stringent requirements of modern high-performance electronic devices on material performance. In particular, silicon-based semiconductor devices have reached their theoretical limits in terms of breakdown voltage and carrier concentration, and cannot be further improved.
[0003] Diamond, as an ideal semiconductor material, has a wide band gap (5.47 eV), high carrier mobility (4500 ), high thermal conductivity (2200 W / mK) and excellent chemical stability, which can meet the needs of high-frequency, high-temperature, small-size, radiation-resistant, high-power and low-power loss electronic devices. Therefore, diamond is considered as the most excellent semiconductor material. The hole mobility of its intrinsic material is 8 times that of silicon, which is much higher than that of SiC and GaN materials by 10 to 50 times; and the thermal conductivity and carrier mobility of diamond are the highest in nature. In terms of breakdown field, the electric field strength of diamond is 30 times that of silicon, 3 to 4 times that of SiC, and even 10 times that of GaN, showing its excellent electronic performance.
[0004] Although the p-type doping technology of diamond has been relatively mature and can meet many application requirements, there are still great technical challenges in n-type doping. At present, the n-type doping of diamond has not yet reached the requirements of practical application in terms of performance indicators such as electron concentration and electron mobility, which limits the wide application of diamond in electronic devices. Therefore, it is particularly important to develop n-type diamond devices complementary to p-type diamond devices. In particular, the theoretical electron mobility of diamond needs to be significantly higher than its hole mobility (electron mobility: 4500 , hole mobility: 3800 ). Therefore, promoting the research and application of n-type diamond devices has important practical significance, which can provide stronger support for the next generation of high-performance electronic devices and promote their wide application in high-frequency, high-power and extreme environments. SUMMARY
[0005] Therefore, the application provides a boron-nitrogen co-doped N-channel diamond field effect tube and a preparation method thereof, aiming to prepare a high-electrical-performance N-channel diamond by using boron-nitrogen co-doping, so as to improve the performance of a metal-oxide-semiconductor field effect transistor (MOSFET).
[0006] In a first aspect, the application provides a preparation method of a MOSFET device, comprising: preparing a P-type substrate; etching the P-type substrate to form a source recess and a drain recess; preparing a boron-nitrogen co-doped N-type diamond layer in the source recess and the drain recess by using an MPCVD process; forming a gate oxide layer on the surface of the P-type substrate; forming a source and a drain on the surface of the N-type diamond layer in the source recess and the drain recess, respectively; preparing a gate on the surface of the gate oxide layer to form a MOSFET device.
[0007] Optionally, the step of preparing a boron-nitrogen co-doped N-type diamond layer in the source recess and the drain recess by using an MPCVD process comprises: turning on a microwave power source, introducing a carbon source, a boron source, a nitrogen source and a growth gas into an MPCVD growth cavity under the condition that the growth temperature is 750-900°C and the growth pressure is 160-210 mbar, and epitaxially obtaining a boron-nitrogen co-doped N-type diamond layer; etching the boron-nitrogen co-doped N-type diamond layer, and retaining the N-type diamond layer in the source recess and the drain recess.
[0008] Optionally, the microwave power of the microwave power source is 3.7-6.0 kW.
[0009] Optionally, the concentration of the carbon source is 4%-8%.
[0010] Optionally, the boron-nitrogen ratio is 1:1-1:4.
[0011] Optionally, the doping concentration of the boron-nitrogen co-doped N-type diamond layer is ~ .
[0012] Optionally, the preparation of the P-type substrate comprises: providing a growth substrate; pre-treating the growth substrate; epitaxially obtaining a P-type diamond substrate on the surface of the growth substrate by using an MPCVD process; removing the growth substrate.
[0013] Optionally, the P-type diamond substrate is epitaxially grown on the surface of the growth substrate by an MPCVD process, comprising: Optionally, the P-type diamond substrate is epitaxially grown on the surface of the growth substrate by an MPCVD process, comprising:
[0014] Optionally, the P-type substrate has a doping concentration of .
[0015] In a second aspect, the present application provides a MOSFET device, comprising: a P-type substrate having a source recess and a drain recess; a boron-nitrogen co-doped N-type diamond layer formed in the source recess and the drain recess; a gate oxide layer formed on the surface of the P-type substrate; a source formed on the surface of the boron-nitrogen co-doped N-type diamond layer in the source recess; a drain formed on the surface of the boron-nitrogen co-doped N-type diamond layer in the drain recess; a gate formed on the surface of the gate oxide layer.
[0016] The technical method provided by the present application has the following beneficial effects: First, the present application provides an n-type single crystal diamond-based MOSFET device and its preparation method, aiming to realize a diamond field effect transistor that can work reliably at high frequency, high power, and high temperature. First, the wide bandgap width of diamond (about 5.5eV) makes it not break down when working at high voltage, thereby improving the voltage withstand capability of the device. This makes the N-type diamond MOSFET capable of withstanding higher voltage than traditional silicon materials, suitable for high-voltage and high-power applications. Second, the low carrier mobility of diamond, but its low electron density makes the leakage current of the diamond MOSFET significantly lower when working, which helps to improve the switching efficiency and reduce power consumption. Third, diamond has extremely high thermal conductivity (about 5 times that of silicon), which can effectively dissipate heat and reduce the performance degradation or failure of the device due to overheating, especially in high power density environments. Finally, the hardness and corrosion resistance of diamond make the MOSFET device more stable and reliable in harsh environments. In summary, the N-type diamond MOSFET improves the overall performance of the device by improving voltage resistance, reducing leakage current, optimizing heat dissipation performance, and enhancing stability, making it suitable for efficient and reliable high-power applications.
[0017] Second, the electrical performance (electron concentration and electron mobility) of the N-type diamond can be improved by preparing the boron-nitrogen co-doped N-type diamond through the MPCVD process, so that the performance of the MOSFET device can be further improved. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0019] Figure 1 The flow chart of the method for manufacturing the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0020] Figure 2 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0021] Figure 3 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0022] Figure 4 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0023] Figure 5 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0024] Figure 6 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0025] Figure 7 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0026] Figure 8 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0027] Figure 9 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0028] Figure 10 The structural schematic diagram in the manufacturing process of the MOSFET device provided by an embodiment of the present application is shown in the figure.
[0029] Figure 11A formation process of a boron-nitrogen co-doped and boron-oxygen co-doped N-type diamond structure provided in the present application can be compared with a diagram Figure 2 A structure schematic diagram in a MOSFET device manufacturing process provided in an embodiment of the present application.
[0030] The reference signs are as follows: 11: P-type substrate; 111: source recess; 112: drain recess; 12: boron-nitrogen co-doped N-type diamond layer; 13: gate oxide layer; 14: source; 15: drain; 16: back electrode; 17: gate. DETAILED DESCRIPTION
[0031] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.
[0032] Figure 1 A preparation method flowchart of a MOSFET device provided in the present application. Referring to Figure 1 , comprising: S101, preparing a P-type substrate.
[0033] In an example, the step S101 comprises: Step 1, providing a growth substrate.
[0034] In an example, the growth substrate is a single crystal diamond substrate.
[0035] As an example, the size of the single crystal diamond substrate is 7mm×7mm×0.25mm, but is not limited thereto.
[0036] Step 2, pretreating the growth substrate.
[0037] In an example, the step 2 comprises: Surface treating the surface of the heterogeneous substrate, and the surface treating method is sequentially cleaning the substrate by a mixed solution of sulfuric acid and nitric acid, acetone, anhydrous ethanol, deionized water, and finally blowing dry with nitrogen.
[0038] The purpose of the surface treatment is to remove the contaminants on the surface of the substrate, and other surface treatment methods can be used as an alternative, which is not limited in the present application.
[0039] Step 3, epitaxially obtaining a P-type diamond substrate on the surface of the growth substrate by using an MPCVD process.
[0040] In an example, the step 3 comprises: The P-type diamond layer is epitaxially obtained by introducing a carbon source with a concentration of 4% to 8% into the MPCVD growth cavity, a boron source with a flow rate of 1 sccm to 20 sccm, and hydrogen with a flow rate of 200 sccm to 550 sccm under a microwave power of 3.7 kW to 6.0 kW, a growth temperature of 750°C to 900°C, and a growth pressure of 160 mbar to 190 mbar.
[0041] In an example, the P-type substrate has a doping concentration of .
[0042] For example, the P-type substrate has a doping concentration of .
[0043] Step 4, removing the growth substrate.
[0044] In an example, after the growth substrate is cut off, the P-type diamond substrate is polished on the side close to the growth substrate.
[0045] Referring to Figure 2 , a P-type substrate 11 is shown.
[0046] S102, etching the P-type substrate to form a source electrode recess and a drain electrode recess.
[0047] In an example, step S102 includes: First, a patterned photoresist layer is prepared on the surface of the P-type substrate.
[0048] The patterned photoresist layer is exposed to the source electrode recess preparation area and the drain electrode recess preparation area.
[0049] The photoresist layer can be prepared by photolithography technology, that is, by sequentially spin-coating photoresist on the surface of the P-type substrate, exposing the photoresist, and developing the photoresist to obtain the patterned photoresist layer.
[0050] Second, etching the side of the P-type substrate with the patterned photoresist layer to form a source electrode recess and a drain electrode recess.
[0051] The etching process includes reactive ion etching, sputter etching, and plasma etching.
[0052] Third, removing the patterned photoresist layer.
[0053] Referring to Figure 3 , a source electrode recess 111 and a drain electrode recess 112 are specifically shown.
[0054] S103, using an MPCVD process to prepare a boron-nitrogen co-doped N-type diamond layer in the source electrode recess and the drain electrode recess.
[0055] In an example, step S103 comprises: Step 1, turn on the microwave power source, and under the environment of a growth temperature of 750-900℃ and a growth pressure of 160-210mbar, introduce carbon source, boron source, nitrogen source and growth gas into the MPCVD growth cavity to epitaxially obtain a boron-nitrogen co-doped N-type diamond layer.
[0056] In an example, the microwave power of the microwave power source is 3.7-6.0kW.
[0057] In an example, the concentration of the carbon source is 4-8%.
[0058] In an example, the boron-nitrogen ratio is 1:1-1:4.
[0059] In an example, the doping concentration of the boron-nitrogen co-doped N-type diamond layer is ~ .
[0060] In an example, the thickness of the boron-nitrogen co-doped N-type diamond layer is 200-500nm.
[0061] Referring to Figure 4 , a boron-nitrogen co-doped N-type diamond layer 12 is specifically shown.
[0062] Step 2, etch the boron-nitrogen co-doped N-type diamond layer to reserve the N-type diamond layer in the source electrode groove and the drain electrode groove.
[0063] In an example, step 2 comprises: First, make a patterned photoresist layer on the surface of the boron-nitrogen co-doped N-type diamond layer.
[0064] The patterned photoresist layer protects the boron-nitrogen co-doped N-type diamond layer in the source electrode groove and the drain electrode groove.
[0065] Second, etch the boron-nitrogen co-doped N-type diamond layer.
[0066] The etching process comprises plasma etching.
[0067] Third, remove the patterned photoresist layer.
[0068] Referring to Figure 5 , a boron-nitrogen co-doped N-type diamond layer 12 after etching is specifically shown.
[0069] S104, form a gate oxide layer on the surface of the P-type substrate.
[0070] First, make a gate oxide layer.
[0071] In an example, the gate oxide layer comprises an Al2O3 layer or a HfO2 layer.
[0072] In an example, the gate oxide layer can be prepared by an atomic layer deposition process.
[0073] In an example, the thickness of the gate oxide layer is 10 nm to 50 nm.
[0074] Referring to Figure 6 , the gate oxide layer 13 is specifically shown.
[0075] In the second step, the gate oxide layer is etched.
[0076] In the second step, the gate oxide layer is etched.
[0077] Referring to Figure 7 , the etched gate oxide layer 13 is shown.
[0078] S105, forming a source and a drain on the surface of the N-type diamond layer in the source recess and the drain recess respectively.
[0079] In an example, the source and the drain are sputtered by a magnetron sputtering method, and a back electrode is also sputtered on the side of the P-type substrate away from the source and the drain.
[0080] In an example, the material of the source, the drain and the back electrode comprises a Ti / Pt / Au or other low work function metal stack structure, to ensure efficient electron injection and extraction.
[0081] Referring to Figure 8 , the source 14, the drain 15 and the back electrode 16 are specifically shown.
[0082] S106, forming a gate on the surface of the gate oxide layer to form a MOSFET device.
[0083] In an example, the gate is sputtered with a Schottky contact on the gate oxide layer.
[0084] In an example, the gate comprises a low work function metal such as Ti, Al or a composite metal structure, to realize threshold voltage optimization of the device by adjusting the work function.
[0085] After the gate is formed, annealing treatment is performed to form the MOSFET device.
[0086] It should be noted that a passivation layer can be optionally formed on the surface of the MOSFET device to improve the reliability of the device. The passivation layer can be a SiN layer with a thickness of 20 nm to 100 nm, and the preparation process thereof can be plasma enhanced chemical vapor deposition (PECVD).
[0087] Referring to Figure 9, specifically shows a MOSFET device, comprising: A P-type substrate 11, which has a source recess 111 and a drain recess 112; A boron-nitrogen co-doped N-type diamond layer 12 formed in the source recess and the drain recess.
[0088] A gate oxide layer 13 formed on the surface of the P-type substrate.
[0089] A source 14 formed on the surface of the boron-nitrogen co-doped N-type diamond layer in the source recess.
[0090] A drain 15 formed on the surface of the boron-nitrogen co-doped N-type diamond layer in the drain recess.
[0091] A back electrode 16 formed on the side of the P-type substrate away from the source and the drain.
[0092] A gate 17 formed on the surface of the gate oxide layer 13.
[0093] Figure 10 A schematic diagram of the test results of the boron-nitrogen co-doped N-type diamond based on the MPCVD process provided in the present application. Referring to Figure 10 , Figure 10 The electron mobility and electron concentration of the N-type diamond prepared by boron-nitrogen co-doping and boron-oxygen co-doping are compared.
[0094] Among them, the electron mobility and electron concentration of the boron-nitrogen co-doped N-type diamond are much higher than those of the boron-oxygen co-doped N-type diamond.
[0095] Figure 11 A comparison chart of the formation energy of the boron-nitrogen co-doped and boron-oxygen co-doped N-type diamond structure provided in the present application, further comparing the formation energy of the boron-nitrogen co-doped and boron-oxygen co-doped N-type diamond structure, Figure 11 The formation energy corresponding to the N-type diamond structure formed by different boron-nitrogen ratios and boron-oxygen ratios is represented.
[0096] It should be noted that the boron-nitrogen co-doped N-type diamond has the following advantages: 1、Boron and nitrogen can form stable boron-nitrogen covalent bond, and the doping formation energy is significantly lower than single phosphorus doping or boron-oxygen co-doping. On the one hand, the boron-nitrogen covalent bond reduces the total energy of the system for charge compensation, on the other hand, the spatial matching of boron-nitrogen covalent bond in the lattice is better, resulting in the minimum lattice distortion, so that it is more difficult to produce high electrical performance N-type doped diamond by boron-nitrogen co-doping. By increasing the doping concentration to improve the electrical performance, as the doping concentration rises, the electrical performance will gradually reach the upper limit without damaging the lattice. Due to the better spatial matching of boron-nitrogen covalent bond in the diamond lattice, the upper limit of the electrical performance of the N-type diamond prepared by boron-nitrogen co-doping is higher, that is, the electron concentration and electron mobility are higher.
[0097] 2、Boron provides holes, nitrogen provides electrons, both form electrically neutral counter-doping, which helps to adjust the local electric potential and suppress self-compensation behavior. Especially in diamond, boron-nitrogen co-doping can make the donor level shallower, improve ionization efficiency, and enhance n-type conductivity. For traditional phosphorus-doped N-type diamond, phosphorus is a typical N-type donor, but due to its deep energy level (about 0.6 eV) and large self-compensation effect (such as forming P-V pairs), the activation efficiency is low and the carrier concentration is limited. For example, compared with boron-oxygen co-doping in the prior art, boron and oxygen doping can form B-O pairs, which can theoretically adjust the carrier concentration, but due to the possibility of inducing deep level traps by oxygen, the overall ionization energy is not ideal, and the charge compensation behavior is unstable.
[0098] 3、Boron-nitrogen co-doping can introduce shallow donor levels without significantly reducing the band gap, optimize the conduction band edge, and improve the overall electronic structure. The energy level introduced by traditional phosphorus doping is usually deep, which is not conducive to the generation of effective carriers, and may introduce impurity states to affect device performance. Boron-oxygen co-doping may introduce neutral defect states in the band gap, which brings electron recombination centers and is not conducive to the improvement of conductivity.
[0099] 4、Boron and nitrogen co-doping can form B-N bonds, which have bond length and bond energy closer to C-C bonds in diamond crystal structure, and the disturbance to the crystal structure after doping is minimal, with the best stability and easy industrial control. Compared with phosphorus doping, the atomic size difference of phosphorus is large, which easily causes local structure relaxation or even forms amorphous regions, and has poor stability. Compared with boron-oxygen co-doping, oxygen doping has strong chemical activity, which is easy to form non-ideal bonding or oxygen vacancies, reducing the structural integrity.
[0100] The MPCVD process for preparing n-type boron-nitrogen co-doped diamond films presents numerous challenges. Boron (B) and nitrogen (N) are introduced into the diamond lattice as co-doping elements, achieving n-type conductivity through the mutual compensation of boron's deep donor energy levels with nitrogen's deep acceptor energy levels. However, boron and nitrogen have extremely low solubility in diamond, and they tend to form numerous BN composite defects, rather than being effectively activated as single dopant atoms. The presence of these composite defects significantly reduces the efficiency of carrier (electron) generation, leading to insufficient n-type conductivity. Furthermore, boron (B) and nitrogen (N) have different efficiencies when incorporated into diamond, making precise control of the boron and nitrogen doping ratio a key challenge in achieving effective n-type doping. Furthermore, factors such as the uniform distribution of the impurity elements and the stability of the reaction environment must also be considered, all of which affect the film's crystal quality, conductivity, and mechanical properties. Furthermore, equipment optimization and annealing processes also influence the film's final properties. Therefore, ensuring precise control of each step is crucial for successfully preparing high-quality doped diamond films.
[0101] In order to solve the problem that n-type semiconductor diamond doping is difficult in the prior art and cannot be effectively applied to high-performance electronic devices, especially high-power devices, the present invention proposes a boron-nitrogen co-doped high-performance n-type single crystal diamond film based on MPCVD technology and its preparation method. The core of the invention is to achieve efficient co-doping of boron and nitrogen by precisely controlling the process parameters during the growth process. In the MPCVD preparation process, high-purity As a carbon source, As carrier gas, and As boron source and nitrogen source respectively, the gas ratio is controlled as follows: : =4~8%, ensuring that the boron-nitrogen concentration ratio is between 1:1 and 1:4 to optimize the compensation effect between p-type holes (boron replaces carbon atoms, donor energy level 0.37eV) and n-type electrons (nitrogen replaces carbon atoms, donor energy level 1.7eV). The growth temperature is controlled in stages. By controlling the microwave power and chamber pressure, the growth temperature is guaranteed to be 750~900℃ to enter stable growth. The temperature gradient is controlled within ±10°C to avoid nitrogen desorption or boron diffusion. The microwave power is set to 3.7~6.0kW. The initial low power reduces surface etching, and the power is increased later to improve 、 、 Dissociation efficiency ( The decomposition rate increased from 20% to 50%). The reaction chamber pressure was 160-210 mbar, and the uniformity of the plasma ball was adjusted to ensure the flatness of the diamond growth surface. During the growth process, the spectral intensity of boron and nitrogen was monitored by in-situ optical emission spectroscopy (OES), and the flow rate was adjusted in real time. These control measures work together to efficiently incorporate boron and nitrogen into the crystal lattice, reducing The composite defects and lattice distortion finally form N-type diamond thin film with electron mobility of 10-1500 , carrier concentration The application significantly improves the application potential of the N-type diamond thin film in high-power devices. Compared with the prior art, the application overcomes the problems of low doping efficiency and poor uniformity by specific gas ratio, temperature segmentation, power dynamic adjustment, pressure bias design and real-time monitoring, and provides a feasible path for the research and development of n-type diamond-based electronic devices.
[0102] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. A method for preparing a MOSFET device, characterized in that: include: preparing a P-type substrate; Etching the P-type substrate to form a source groove and a drain groove; Using MPCVD process to form boron and nitrogen co-doped N-type diamond layer in the source groove and drain groove; forming a gate oxide layer on the surface of the P-type substrate; forming a source electrode and a drain electrode on the surface of the N-type diamond layer in the source electrode groove and the drain electrode groove respectively; A gate is fabricated on the surface of the gate oxide layer to form a MOSFET device.
2. The method for preparing a MOSFET device according to claim 1, wherein: The steps of forming a boron-nitrogen co-doped N-type diamond layer in the source groove and the drain groove using the MPCVD process include: Turn on the microwave power supply, introduce a carbon source, a boron source, a nitrogen source, and a growth gas into the MPCVD growth chamber at a growth temperature of 750°C to 900°C and a growth pressure of 160mbar to 210mbar, and epitaxially grow a boron-nitrogen co-doped N-type diamond layer. The boron and nitrogen co-doped N-type diamond layer is etched to retain the N-type diamond layer in the source groove and the drain groove.
3. The method for preparing a MOSFET device according to claim 2, wherein: The microwave power of the microwave power supply is 3.7kW~6.0kW.
4. The method for preparing a MOSFET device according to claim 2, wherein: The carbon source concentration is 4%~8%.
5. The method for preparing a MOSFET device according to claim 2, wherein: The boron-nitrogen ratio is 1:1~1:
4.
6. The method for preparing a MOSFET device according to claim 1, wherein: The doping concentration of the boron and nitrogen co-doped N-type diamond layer is ~ .
7. The method for preparing a MOSFET device according to any one of claims 1 to 6, wherein: Preparation of a P-type substrate includes: providing a growth substrate; pre-treating the growth substrate; The MPCVD process is used to epitaxially grow a P-type diamond substrate on the surface of the growth substrate; The growth substrate is removed.
8. The method for preparing a MOSFET device according to claim 7, wherein: The method of epitaxially growing a P-type diamond substrate on a growth substrate using the MPCVD process includes: Under a growth temperature of 750℃~900℃ and a growth pressure of 160mbar~190mbar, a carbon source with a concentration of 4%~8%, a boron source with a flow rate of 1sccm~20sccm, and a hydrogen flow rate of 200sccm~550sccm are introduced into the MPCVD growth chamber with a microwave power of 3.7kW~6.0kW to obtain a P-type diamond layer by epitaxy.
9. The method for preparing a MOSFET device according to any one of claims 1 to 6, wherein: The doping concentration of the P-type substrate is ~ .
10. A MOSFET device, characterized in that: include: A P-type substrate having a source groove and a drain groove; a boron and nitrogen co-doped N-type diamond layer formed in the source groove and the drain groove; A gate oxide layer is formed on the surface of the P-type substrate; A source electrode formed on a surface of a boron-nitrogen co-doped N-type diamond layer in a source electrode groove; A drain electrode formed on a surface of a boron-nitrogen co-doped N-type diamond layer in a drain groove; The gate is formed on the surface of the gate oxide layer.