Diamond field effect transistor with enhanced carrier mobility and method of making the same

Abstract

The application discloses a diamond field effect transistor with enhanced carrier mobility and a preparation method thereof, and the diamond field effect transistor comprises: a single-crystal diamond epitaxial film arranged on a diamond substrate; the single-crystal diamond epitaxial film is provided with a first heavily doped diamond film region and a second heavily doped diamond film region; a hydrogen terminal region is arranged on the surface of the single-crystal diamond epitaxial film between the first heavily doped diamond film region and the second heavily doped diamond film region and on the surface of the single-crystal diamond epitaxial film, and an oxygen terminal region is arranged on the surface of the remaining epitaxial film; a source electrode and a drain electrode are both arranged on a channel region; a gate dielectric layer is arranged on the source electrode, the drain electrode and the channel region therebetween, and a gate electrode is arranged on the gate dielectric layer and the oxygen terminal region. The heavily doped diamond film region is formed in the single-crystal diamond film, and the mobility of holes can be improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, and specifically relates to a diamond field-effect transistor with enhanced carrier mobility and its fabrication method. Background Technology

[0002] Diamond exhibits ultra-wide bandgap (5.45 eV) and high carrier mobility (electron: 4500 cm⁻¹). 2 / Vs, Hole: 3800cm 2 / Vs), thermal conductivity (22W / cmK), breakdown field strength (>10MV / cm), dielectric constant, saturated carrier drift velocity (electrons: 2.7×10 7 cm / s, holes: 1.1×10 7 Diamond surpasses other semiconductors in several aspects, including performance in terms of speed (cm / s), radiation resistance, and corrosion resistance. It also boasts the highest quality factors, such as Johnson, Keyes, and Baliga, covering the widest range of applications in terms of output power and operating frequency. Due to its superior performance, diamond will undoubtedly play a crucial role in high-temperature, high-efficiency, high-frequency, and high-power semiconductor power devices, thus becoming a next-generation semiconductor chip material and ushering in a new era for the development of ultra-large-scale and ultra-high-speed integrated circuits.

[0003] In existing technologies, although the carrier mobility of hydrogen-terminated diamond has reached 680 cm⁻¹, 2 ·V -1 ·s -1 However, it is still lower than that of silicon devices (electron mobility is approximately 1350 cm⁻¹). 2 ·V -1 ·s -1 The hole mobility is approximately 480 cm. 2 ·V -1 ·s -1 ) and GaNHEMT (electron mobility approximately 2000 cm⁻¹) 2 ·V -1 ·s -1 The carrier mobility in diamond is far from reaching the theoretical value (theoretically predicted to be greater than 3000 cm⁻¹ after solving the problems of interfacial ionized impurity scattering and roughness scattering). 2 ·V -1 ·s -1 ).

[0004] Based on the above analysis, there is an urgent need for a new diamond field-effect transistor with enhanced carrier mobility and its fabrication method. Summary of the Invention

[0005] The purpose of this invention is to provide a diamond field-effect transistor with enhanced carrier mobility and its fabrication method, thereby solving one or more of the aforementioned technical problems. In the technical solution provided by this invention, a heavily doped diamond film is formed in a single-crystal diamond film, providing compressive stress to the channel region and the single-crystal diamond film below, which can improve hole mobility and effectively enhance the electrical characteristics of the device, such as current density.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The present invention provides a diamond field-effect transistor with enhanced carrier mobility, comprising: a diamond substrate, a single-crystal diamond epitaxial film, a gate dielectric layer, a source electrode, a drain electrode, and a gate electrode;

[0008] The single-crystal diamond epitaxial film is disposed on the diamond substrate;

[0009] The single-crystal diamond epitaxial film is provided with a first heavily doped diamond film region and a second heavily doped diamond film region; a hydrogen terminal region is provided on the surface of the single-crystal diamond epitaxial film in the first heavily doped diamond film region, the second heavily doped diamond film region and the region between them, and an oxygen terminal region is provided on the surface of the remaining single-crystal diamond epitaxial film; wherein, the hydrogen terminal region is a channel region composed of a two-dimensional hole gas conductive layer.

[0010] Both the source electrode and the drain electrode are disposed on the channel region;

[0011] The gate dielectric layer is disposed on the source electrode, the drain electrode, and the channel region between them;

[0012] The gate electrode is disposed on the gate dielectric layer and the oxygen terminal region.

[0013] A further improvement of the present invention is that the doping concentration of the first heavily doped diamond film and the second heavily doped diamond film is 10. 19 cm -2 ~10 21 cm -2 It has a resistivity of less than 100 mΩ·cm, a width of 10 μm to 500 μm, a depth of 10 nm to 5 μm, and internal tensile stress.

[0014] A further improvement of the present invention is that the doping elements in the first heavily doped diamond film and the second heavily doped diamond film include one or more of boron, aluminum, phosphorus and nitrogen.

[0015] A further improvement of the present invention is that the channel length in the channel region is 20 nm to 100 μm, and the carrier concentration in the channel is 5 × 10⁻⁶. 12cm -2 ~5×10 14 cm -2 The migration rate is 20cm. 2 / V·s~2500cm 2 / V·s.

[0016] A further improvement of the present invention is that the gate dielectric layer is made of an insulating material.

[0017] The present invention provides a method for fabricating a diamond field-effect transistor with enhanced carrier mobility, comprising the following steps:

[0018] Step 1: Clean and dry the diamond substrate to obtain the cleaned diamond substrate;

[0019] Step 2: Homogeneously epitaxial single-crystal diamond film is formed on the diamond substrate obtained in Step 1 to obtain single-crystal diamond epitaxial film;

[0020] Step 3: A heavily doped diamond film is formed in the preset region of the single-crystal diamond epitaxial film obtained in step 2, thus obtaining the first heavily doped diamond film region and the second heavily doped diamond film region.

[0021] Step 4: Perform hydrogenation treatment on the surface of the single-crystal diamond epitaxial film to obtain a hydrogen-terminated region; the hydrogen-terminated region on the surface of the first heavily doped diamond film, the second heavily doped diamond film, and the single-crystal diamond epitaxial film between them are used as the channel region.

[0022] Step 5: Using photolithography, source electrode and drain electrode patterns are formed on the channel region above the first doped diamond film region and the second doped diamond film region, respectively. Source electrode and drain electrode metals are deposited, and ohmic contacts between the source electrode and drain electrode are obtained using lift-off technology.

[0023] Step 6: Deposit a gate dielectric layer on the source electrode, the drain electrode, and the channel region between them;

[0024] Step 7: Using the gate dielectric layer obtained in Step 6 as a mask, perform oxygen termination treatment to form an oxygen termination region.

[0025] Step 8: Use photolithography to form a gate electrode pattern on the gate dielectric layer and the oxygen terminal region, and deposit gate electrode metal to obtain the gate electrode.

[0026] A further improvement of the present invention is that, in step 3, the step of forming a heavily doped diamond film in the preset region of the single-crystal diamond epitaxial film obtained in step 2 specifically includes:

[0027] In the predetermined region of the single-crystal diamond epitaxial film obtained in step 2, a heavily doped diamond film is formed by etching and selective epitaxial growth, diffusion or ion implantation processes.

[0028] A further improvement of the present invention is that, when forming a heavily doped diamond thin film through etching and selective epitaxial growth processes,

[0029] First, ICP etching is performed on the single-crystal diamond epitaxial film with an RF power of 200W to 1000W, a DC power of 50W to 300W, and an etching time of 30s to 1800s. Then, selective epitaxial growth is performed with a cavity temperature of 800℃ to 1200℃ and a cavity pressure of 3kPa to 18kPa.

[0030] A further improvement of the present invention is that, when forming a heavily doped diamond thin film by a diffusion process,

[0031] The compound containing the dopant is coated onto the surface of a single-crystal diamond epitaxial film, and then annealed in stages at temperatures ranging from 300°C to 400°C, from 600°C to 1800°C, to form a heavily doped film.

[0032] A further improvement of the present invention is that, when forming a heavily doped diamond thin film by ion implantation,

[0033] Ion energy ranges from 20 keV to 1500 keV, and the implanted ion dose is 10. 15 cm -2 ~10 20 cm -2 .

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The diamond field-effect transistor with enhanced carrier mobility provided by this invention forms heavily doped regions in a single-crystal diamond film. The heavily doped regions apply compressive stress to the single-crystal diamond film between them, changing the shape of the crystal lattice and thus altering the degree of band bending. This leads to a reduction in the effective mass of holes, thereby increasing the carrier mobility of holes and effectively improving the electrical characteristics of the device, such as current density. At the same time, the heavily doped regions can form good ohmic contacts. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0037] Figure 1This is a schematic diagram of the cross-sectional structure of a diamond field-effect transistor with enhanced carrier mobility provided in an embodiment of the present invention;

[0038] Figure 2 This is a top view schematic diagram of a diamond field-effect transistor with enhanced carrier mobility provided in an embodiment of the present invention;

[0039] Figure 3 This is a schematic flowchart of a method for fabricating a diamond field-effect transistor with enhanced carrier mobility provided in an embodiment of the present invention;

[0040] In the figure, 1 is the diamond substrate; 2 is the single-crystal diamond epitaxial film; 3 is the heavily doped diamond film; 4 is the channel region; 5 is the insulating isolation region; 6 is the gate dielectric layer; 7 is the source electrode; 8 is the drain electrode; and 9 is the gate electrode. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention 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. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] The present invention will now be described in further detail with reference to the accompanying drawings:

[0044] Please see Figure 1 and Figure 2This invention provides a diamond field-effect transistor with enhanced carrier mobility, comprising: a diamond substrate 1, a single-crystal diamond epitaxial film 2, a heavily doped diamond film 3 (specifically, it may include a first heavily doped diamond film region and a second heavily doped diamond film region), a channel region 4, an insulating isolation region 5, a gate dielectric layer 6, a source electrode 7, a drain electrode 8, and a gate electrode 9; wherein, the diamond substrate 1 is provided with a single-crystal diamond epitaxial film 2 and a heavily doped diamond film 3 (more specifically, a heavy doped diamond film 3 is formed in the single-crystal diamond epitaxial film 2). The single-crystal diamond epitaxial film 2 and the heavily doped diamond film 3 are provided with a channel region 4 and an insulating isolation region 5. The channel region 4 is a hydrogen terminal region and the insulating isolation region 5 is an oxygen terminal region. The channel region 4 includes a two-dimensional hole gas conductive layer, in which charge carriers can migrate. The gate dielectric layer 6 is located on the channel region 4, the source electrode 7 and the drain electrode 8. It is an insulating material in which charge carriers cannot be transported. The source electrode 7 and the drain electrode 8 are located on the channel region 4 above the heavily doped diamond film. The gate electrode 9 is disposed on the gate dielectric layer 6.

[0045] In a specific exemplary embodiment of the present invention, the single-crystal diamond epitaxial film 2 can be a diamond material grown by chemical vapor deposition (CVD), in which compressive stress is generated, with a stress magnitude of 10 MPa to 5 GPa, a resistivity greater than 100 mΩ·cm, a root mean square surface roughness of less than 0.5 nm, and a Raman curve half-width of less than 2 cm. -1 The half-width of the XRD rocking curve is less than 30 arcsec.

[0046] In a preferred embodiment of the present invention, the doping concentration of the heavily doped diamond film 3 is 10. 19 ~10 21 cm -2 It has a resistivity of less than 100 mΩ·cm, a width of 10 μm to 500 μm, and a depth of 10 nm to 5 μm. It generates tensile stress inside and is formed by etching / selective epitaxial growth, diffusion, ion implantation and other methods. The doping elements include one or more of boron, aluminum, phosphorus and nitrogen.

[0047] In a specific exemplary embodiment of the present invention, the channel region 4 is a hydrogen terminal surface, the channel length is 20 nm to 100 μm, and the carrier concentration within the channel is 5 × 10⁻⁶. 12 ~5×10 14 cm -2 The migration rate is 20–2500 cm. 2 / V·s.

[0048] In this embodiment of the invention, the gate dielectric layer 6 is made of an insulating material, such as SiN. xMaterials such as SiO2, Al2O3, ZrO2, and high work function materials; further explanation is that they can be formed by deposition techniques such as electron beam evaporation, sputtering, and atomic layer deposition.

[0049] In this embodiment of the invention, the source electrode 7 and drain electrode 8 are made of Au, Pd, Ir, Pt or Ti, and the gate electrode 9 is made of Al, Zr, Hf and Mo, etc.; wherein, the material of the source and drain electrodes 8 is capable of forming an ohmic contact with the hydrogen terminal.

[0050] The carrier mobility-enhanced diamond field-effect transistor disclosed in this invention improves device performance by forming a heavily doped diamond thin film, which alters the stress distribution in the original single-crystal diamond thin film, thereby reducing the effective hole mass and increasing hole mobility. The heavily doped region can form a low on-resistance.

[0051] Please see Figure 3 The present invention provides a diamond field-effect transistor with enhanced carrier mobility, comprising the following steps:

[0052] Step 1: Clean the diamond substrate 1 and dry it;

[0053] Step 2: Homogeneously epitaxial single-crystal diamond film is formed on diamond substrate 1 to obtain single-crystal diamond epitaxial film 2;

[0054] Step 3: In a portion of the single-crystal diamond epitaxial film 2, a heavily doped diamond film 3 is formed by etching / selective epitaxial growth, diffusion, ion implantation and other techniques.

[0055] Step 4: Hydrogenation treatment is performed on the single-crystal diamond epitaxial film 2 and the heavily doped diamond film 3 to obtain a two-dimensional hole gas conductive layer, forming the channel region 4.

[0056] Step 5: Using photolithography, source and drain electrode patterns are formed on the channel region 4 above the heavily doped diamond film 3, source and drain electrode metals are deposited, and ohmic contact between the source electrode 7 and the drain electrode 8 is obtained using lift-off technology.

[0057] Step 6: Deposit a gate dielectric layer 6 on the channel region 4, part of the source electrode 7 and the drain electrode 8;

[0058] Step 7: Using the gate dielectric layer 6 as a mask, oxygen termination treatment is performed on the sample to form an insulating isolation region 5;

[0059] Step 8: Use photolithography to form a gate electrode pattern on the gate dielectric layer 6 and deposit the gate electrode metal.

[0060] The doping techniques disclosed in the above steps of this invention include ion implantation, diffusion, microwave plasma chemical vapor deposition, etc.; photolithography techniques include ultraviolet lithography, electron beam lithography, and step-through non-contact lithography, etc.; dry etching techniques include inductively coupled plasma etching, reactive ion etching, ion beam etching, and focused ion beam etching, etc.; non-metal deposition methods include electron beam deposition, sputtering, and atomic layer deposition, etc.; metal deposition methods include thermal evaporation, electron beam evaporation, sputtering, and atomic layer deposition, etc.

[0061] In step 3 of this embodiment of the invention, when a heavily doped diamond film 3 is formed in a portion of the single-crystal diamond epitaxial film 2, its doping concentration is 10. 19 ~10 21 cm -2 The resistivity is less than 100 mΩ·cm, the width is 10–500 μm, and the depth is 10 nm–5 μm. Tensile stress is generated within the film, which is formed by etching / selective epitaxial growth, diffusion, and ion implantation. Doping elements include boron, aluminum, phosphorus, and nitrogen. In the etching / selective epitaxial growth process, the single-crystal diamond epitaxial film 2 is first etched using ICP etching at a radio frequency power of 200–1000 W, a DC power of 50–300 W, and an etching time of 30–1800 s. This is followed by selective epitaxial growth at a chamber temperature of 800–1200 °C and a chamber pressure of 3–18 kPa. The diffusion method involves coating the sample surface with a dopant compound and annealing it in stages at 600–1800 °C with temperature variations of 300–400 °C to form a heavily doped region. In the ion implantation method, the ion energy is 20–1500 keV, and the implanted ion dose is 10... 15 ~10 20 cm -2 .

[0062] In step 4 of this embodiment, the hydrogenation treatment involves placing the diamond sample in a hydrogen plasma or hydrogen atmosphere at a temperature of 700–1000°C for 10 seconds to 2 hours, resulting in a carrier concentration of 5 × 10⁻⁶ in the hydrogen terminal channel region. 12 ~5×10 14 cm -2 The migration rate is 20–2500 cm. 2 / V·s.

[0063] In the fabrication method provided in this embodiment of the invention, the source / drain electrode metal deposited in step 5 is Au, Pd, Ir, Pt, or Ti, etc. The gate dielectric layer in step 6 is an insulating material, such as SiN. x Materials include SiO2, Al2O3, ZrO2, and high work function materials. In step 8, the gate electrode material is made of Al, Zr, Hf, and Mo, among others.

[0064] In this embodiment of the invention, the oxygen terminal treatment electrical isolation in step 7 specifically includes: treating the surface of the single-crystal diamond epitaxial film 2 and the heavily doped diamond film 3 with ultraviolet light / ozone or oxygen plasma, wherein the gas flow rate of oxygen or ozone is 1-100 sccm, the plasma power is 100-300 W, and the treatment time is 1-60 min.

[0065] In summary, the carrier mobility-enhanced diamond field-effect transistor provided in this embodiment of the invention comprises a diamond substrate, a single-crystal diamond epitaxial film, a heavily doped diamond film, a channel region (hydrogen terminal), an insulating isolation region (oxygen terminal), a source electrode, a drain electrode, a gate dielectric layer, and a gate electrode. The diamond substrate has a single-crystal diamond epitaxial film and a heavily doped diamond film. The diamond film has a channel region (hydrogen terminal) and an insulating isolation region (oxygen terminal). A source electrode and a drain electrode are disposed on the channel region above the heavily doped diamond film, and a gate dielectric layer is disposed above the channel region and part of the source and drain electrodes. A gate electrode is disposed on the gate dielectric layer. The technical solution disclosed in this invention forms a heavily doped diamond film in a single-crystal diamond film, thereby changing the stress distribution in the original single-crystal diamond film. Compressive stress is applied to the single-crystal diamond epitaxial film in the middle of the heavily doped region, which increases the carrier mobility in the channel, reduces the effective hole mass, and increases the hole mobility. At the same time, the heavily doped region can form a good ohmic contact, thereby improving the electrical performance of existing hydrogen-terminated diamond devices.

[0066] Example 1

[0067] The present invention discloses a method for fabricating a diamond field-effect transistor with enhanced carrier mobility, comprising the following steps:

[0068] 1) The diamond substrate 1 grown by high temperature and high pressure (HPHT) technology was subjected to inorganic and organic cleaning processes using the standard cleaning process of diamond substrate 1, and then dried with nitrogen gas for later use.

[0069] 2) A single-crystal diamond film was deposited on the cleaned diamond substrate 1 using microwave plasma chemical deposition (MPCVD). The plasma power was 1 kW, the chamber pressure was 100 Torr, and the total gas flow rate was 500 sccm. The resulting single-crystal diamond film had a thickness of 1 μm, a resistivity greater than 100 mΩ·cm, a root mean square surface roughness of 0.45 nm, and a Raman curve half-width of 1.9 cm. -1 The half-peak width of the XRD rocking curve is 29 arcsec.

[0070] 3) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the single-crystal diamond sample with the photoresist coated at 95°C for 90 seconds. Perform ultraviolet lithography exposure using the designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the Pd mask area pattern. Place the photolithographically patterned sample in the magnetron sputtering chamber, and evacuate the sample chamber to a background vacuum of 5 × 10⁻⁶. -6 After torsion, the sample is transferred to the main chamber, argon gas is introduced at 5 sccm, sputtering power is set to 100W, and deposition is carried out for 20 min. The Pd metal deposited sample is removed, immersed in N-methylpyrrolidone (NMP) solution, and the metal outside the exposed area is ultrasonically stripped off. After cleaning, it is dried with nitrogen. The sample containing the Pd metal mask pattern is placed in the sample chamber of an inductively coupled plasma (ICP) etching machine, and the sample chamber background vacuum is evacuated to 5 × 10⁻⁶. - 6 After Torr, the sample was transferred to the main chamber, and oxygen at 30 sccm and argon at 5 sccm were introduced. The ICP RF power was set to 500W and the DC power to 100W, and the etching time was 120s. The etched diamond sample was then removed and sonicated for 15 minutes each in acetone, alcohol, and pure water to remove organic matter and impurities from the sample surface. It was then dried with an air gun for later use. Doped single-crystal diamond homoepitaxial growth was performed using microwave plasma-enhanced chemical vapor deposition (MPCVD) with trimethylaluminum (TMAl) as the dopant gas and an aluminum-to-carbon ratio (Al / C) of 500 × 10⁻⁶. -6 The growth temperature was 1000℃, the CH4 concentration (CH4 / H2) was 4%, the chamber pressure was 160 mbar (1 mbar = 100 Pa), and the doping concentration was 10. 19 cm -3 After deposition, the compressive stress within the single-crystal diamond epitaxial film 2 was 0.8 GPa. After deposition, grinding and polishing were performed to achieve a surface roughness of less than 0.5 nm.

[0071] 4) The sample was first cleaned with inorganic and then with organic solvents, dried with nitrogen, and then placed in the microwave plasma chemical vapor deposition (MPCVD) chamber. The microwave plasma power was controlled to maintain the chamber temperature at 900℃ and the hydrogen flow rate at 50 sccm. The grown single-crystal diamond epitaxial film 2 and the heavily doped p-type diamond film were hydrogenated for 5 min to obtain a two-dimensional hole gas surface density of 2 × 10⁻⁶. 13 cm -2 The mobility is 1500 cm. 2 / V·s.

[0072] 5) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the source and drain electrode patterns. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, two metal layers, Pd and Au, were sequentially deposited on the sample surface, with thicknesses of 50 nm and 500 nm, respectively. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the source electrode 7 and the drain electrode 8.

[0073] 6) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then blow dry. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95℃ for 90s. Expose it to ultraviolet light using a pre-designed mask for 4s, and develop it for 30s to remove the exposed photoresist, leaving the gate dielectric layer pattern. Place the photolithographically patterned sample in an electron beam evaporation device to deposit a ZrO2 layer on the sample surface. Remove the deposited diamond sample, immerse it in N-methylpyrrolidone (NMP) solution, and bathe it in a 120℃ water bath for 5 minutes. Then, ultrasonically peel off the oxides outside the exposed area to obtain the gate dielectric layer 6.

[0074] 7) Clean the sample with acetone, isopropanol, and deionized water using ultrasonic cleaning and then blow it dry; use the dielectric layer as a mask to treat the sample with oxygen plasma for 5 minutes at a power of 30W and an oxygen flow rate of 80sccm, transforming the two sides of the channel region 4 into an insulating isolation region 5.

[0075] 8) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat a layer of AZ5214 photoresist onto the sample surface. Bake the single-crystal diamond sample with the photoresist coated at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the gate electrode pattern. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, Al and Au metals of 50 nm and 300 nm were sequentially deposited on the sample surface. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the gate electrode 9, and finally the fabricated diamond field-effect transistor with enhanced carrier mobility was obtained.

[0076] Example 2

[0077] The present invention discloses a method for fabricating a diamond field-effect transistor with enhanced carrier mobility, comprising the following steps:

[0078] 1) The diamond substrate 1 grown by high temperature and high pressure (HPHT) technology was subjected to inorganic and organic cleaning processes using the standard cleaning process of diamond substrate 1, and then dried with nitrogen gas for later use.

[0079] 2) A single-crystal diamond film was deposited on the cleaned diamond substrate 1 using microwave plasma chemical deposition (MPCVD). The plasma power was 1.2 kW, the chamber pressure was 100 Torr, and the total gas flow rate was 500 sccm. The resulting single-crystal diamond film had a thickness of 2 μm, a resistivity greater than 100 mΩ·cm, a root mean square surface roughness of 0.4 nm, and a Raman curve half-width of 1.9 cm. -1 The half-peak width of the XRD rocking curve is 25 arcsec.

[0080] 3) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Perform UV lithography exposure using the designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the Pt mask area pattern. Place the lithographically patterned sample in the magnetron sputtering chamber, and evacuate the sample chamber to a background vacuum of 5 × 10⁻⁶. -6 After torsion, the sample is transferred to the main chamber, argon gas is introduced at 5 sccm, sputtering power is set to 80 W, and deposition is carried out for 30 min. The Pt metal deposited sample is removed, immersed in N-methylpyrrolidone (NMP) solution, and the metal outside the exposed area is ultrasonically stripped off. After cleaning, it is dried with nitrogen. The sample containing the Pt metal mask pattern is placed in the sample chamber of an inductively coupled plasma (ICP) etching machine, and the sample chamber background vacuum is evacuated to 5 × 10⁻⁶. - 6 After Torr, the sample was transferred to the main chamber, and oxygen (30 sccm) and argon (5 sccm) were introduced. The ICP RF power was set to 300W and the DC power to 80W, and etching was performed for 600 seconds. The etched diamond sample was then removed and sonicated for 15 minutes each in acetone, alcohol, and pure water to remove organic matter and impurities from the sample surface. It was then dried with an air gun for later use. Homoethropometric growth of doped single-crystal diamond was performed using chemical vapor deposition (CVD). The doping gas was a mixture of methane, triethyl borate, and hydrogen. The growth temperature was 1100℃, the chamber pressure was 10 kPa, and the flow rate of methane into the reactor was 25 sccm; the flow rate of the triethyl borate and hydrogen mixture was 10 sccm. After deposition, the compressive stress within the single-crystal diamond epitaxial film 2 was 0.9 GPa. After deposition, grinding and polishing were performed to achieve a surface roughness of less than 0.5 nm.

[0081] 4) The sample was first cleaned with inorganic and then with organic solvents, dried with nitrogen, and then placed in the microwave plasma chemical vapor deposition (MPCVD) chamber. The microwave plasma power was controlled to maintain the chamber temperature at 900℃ and the hydrogen flow rate at 50 sccm. The grown single-crystal diamond epitaxial film 2 and the heavily doped p-type diamond film were hydrogenated for 5 min to obtain a two-dimensional hole gas surface density of 2 × 10⁻⁶. 13 cm -2 The mobility is 1200 cm. 2 / V·s.

[0082] 5) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the source and drain electrode patterns. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, two metal layers, Pd and Au, were sequentially deposited on the sample surface, with thicknesses of 50 nm and 200 nm, respectively. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the source electrode 7 and the drain electrode 8.

[0083] 6) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose it to ultraviolet light using a pre-designed mask for 4 seconds, and develop it for 30 seconds to remove the exposed photoresist, leaving the gate dielectric layer pattern. Place the photolithographically patterned sample in an electron beam evaporation apparatus to deposit a high work function WO3 layer on the sample surface. Remove the deposited diamond sample, immerse it in N-methylpyrrolidone (NMP) solution, and bathe it in a 120°C water bath for 5 minutes. Then, ultrasonically peel off the oxides outside the exposed area to obtain the gate dielectric layer 6.

[0084] 7) Clean the sample with acetone, isopropanol, and deionized water using ultrasonic cleaning and then blow dry; treat the sample with ultraviolet / ozone equipment for 15 minutes using a high work function dielectric material as a mask to transform the two sides of the channel region 4 into an insulating isolation region 5.

[0085] 8) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat a layer of AZ5214 photoresist onto the sample surface. Bake the single-crystal diamond sample with the photoresist coated at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the gate electrode pattern. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, Al and Au metals were sequentially deposited on the sample surface at 50 nm and 300 nm. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the gate electrode 9, and finally, a diamond field-effect transistor with enhanced carrier mobility was obtained.

[0086] Example 3

[0087] The present invention provides a method for fabricating a diamond field-effect transistor with enhanced carrier mobility, comprising the following steps:

[0088] 1) The diamond substrate 1 grown by high temperature and high pressure (HPHT) technology was subjected to inorganic and organic cleaning processes using the standard cleaning process of diamond substrate 1, and then dried with nitrogen gas for later use.

[0089] 2) A single-crystal diamond film was deposited on the cleaned diamond substrate 1 using microwave plasma chemical deposition (MPCVD). The plasma power was 1.2 kW, the chamber pressure was 100 Torr, and the total gas flow rate was 500 sccm. The resulting single-crystal diamond film had a thickness of 3 μm, a resistivity greater than 100 mΩ·cm, a root mean square surface roughness of 0.35 nm, and a Raman curve half-width of 1.8 cm. -1 The half-peak width of the XRD rocking curve is 26 arcsec.

[0090] 3) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Perform UV lithography exposure using the designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the W mask area pattern. Place the lithographically patterned sample in the magnetron sputtering chamber, and evacuate the sample chamber to a background vacuum of 5 × 10⁻⁶. -6 After torsion, the sample is transferred to the main chamber, argon gas is introduced at 5 sccm, sputtering power is set to 100W, and deposition is carried out for 20 min. The sample with deposited W metal is removed, immersed in N-methylpyrrolidone (NMP) solution, and the metal outside the exposed area is ultrasonically stripped off. After cleaning, it is dried with nitrogen gas. The sample containing the W metal mask pattern is placed in the sample chamber of an inductively coupled plasma (ICP) etching machine, and the sample chamber background vacuum is evacuated to 5 × 10⁻⁶.-6 After Torr, the sample is transferred to the main chamber, and oxygen at 30 sccm and argon at 5 sccm are introduced. The ICP RF power is set to 500W and the DC power to 100W, and the etching time is 1200s. The etched diamond sample is then removed and ultrasonicated for 15 minutes each in acetone, alcohol, and pure water to remove organic matter and impurities from the sample surface. It is then dried with an air gun for later use. Nitrogen-doped diamond films are prepared using hot-wire chemical vapor deposition (HFCVD). A 0.3mm tungsten wire is wound into a spiral shape with 10 turns. The hot-wire temperature is 2200℃, the distance between the hot-wire and the single-crystal diamond film is 8mm, and the surface temperature of the single-crystal diamond film is 800℃. The gas source is a mixture of methane and hydrogen (H2:CH4 = 100:1), and the doping gas is a mixture of nitrogen and hydrogen (H2:N2 = 95:5). The chamber pressure is 3.5kPa, and the gas flow rate is 100 sccm.

[0091] 4) The sample was first cleaned with inorganic and then with organic solvents, dried with nitrogen, and then placed in the cavity of a microwave plasma chemical vapor deposition (MPCVD) equipment. The microwave plasma power was controlled to maintain the cavity temperature at 750℃ and the hydrogen flow rate at 100 sccm. The grown single-crystal diamond epitaxial film 2 and the heavily doped p-type diamond film were hydrogenated for 20 min, resulting in a two-dimensional hole gas surface density of 2 × 10⁻⁶. 13 cm -2 The mobility is 1500 cm. 2 / V·s.

[0092] 5) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the source and drain electrode patterns. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, two metal layers, Pd and Au, were sequentially deposited on the sample surface, with thicknesses of 50 nm and 500 nm, respectively. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the source electrode 7 and the drain electrode 8.

[0093] 6) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95℃ for 90s. Expose it to ultraviolet light using a pre-designed mask for 4s, and develop it for 30s to remove the exposed photoresist, leaving the gate dielectric layer pattern. Place the photolithographically patterned sample in a magnetron sputtering apparatus to deposit a BaF2 layer on the sample surface. Remove the deposited diamond sample, immerse it in N-methylpyrrolidone (NMP) solution, and bathe it in a 120℃ water bath for 5 minutes. Then, ultrasonically peel off the dielectric layer outside the exposed area to obtain the gate dielectric layer 6.

[0094] 7) Clean the sample with acetone, isopropanol, and deionized water using ultrasonic cleaning and then blow dry; use BaF2 dielectric layer as a mask to treat the sample with oxygen plasma for 3 minutes at a power of 80W and an oxygen flow rate of 100sccm, transforming the two sides of the channel region 4 into an insulating isolation region 5.

[0095] 8) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat a layer of AZ5214 photoresist onto the sample surface. Bake the single-crystal diamond sample with the photoresist coated at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the gate electrode pattern. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, Al and Au metals were deposited sequentially at 50 nm and 300 nm on the sample surface. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the gate electrode 9, and finally, a diamond field-effect transistor with enhanced carrier mobility was obtained.

[0096] Example 4

[0097] The present invention provides a method for fabricating a diamond field-effect transistor with enhanced carrier mobility, comprising the following steps:

[0098] 1) The diamond substrate 1 grown by high temperature and high pressure (HPHT) technology was subjected to inorganic and organic cleaning processes using the standard cleaning process of diamond substrate 1, and then dried with nitrogen gas for later use.

[0099] 2) A single-crystal diamond film was deposited on the cleaned diamond substrate 1 using microwave plasma chemical deposition (MPCVD). The plasma power was 1.5 kW, the chamber pressure was 100 Torr, and the total gas flow rate was 500 sccm. The resulting single-crystal diamond film had a thickness of 3 μm, a resistivity greater than 100 mΩ·cm, a root mean square surface roughness of 0.4 nm, and a Raman curve half-width of 1.7 cm.-1 The half-peak width of the XRD rocking curve is 28 arcsec.

[0100] 3) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the single-crystal diamond sample with the photoresist coating at 95℃ for 90s. Expose the sample to ultraviolet light using a pre-designed mask for 4s, followed by development for 30s to remove the exposed photoresist, leaving the pattern of the ion implantation area. Harden the remaining photoresist at 120℃ for 120s. Place the photolithographically patterned sample in an ion implantation device, and then implant phosphorus ions at an energy of 100keV at room temperature. The phosphorus ion implantation dose is 10. 15 cm -2 Subsequently, the sample was annealed at 850℃ to restore its crystallinity, resulting in a heavily doped N-type diamond film. After ion implantation, the compressive stress in the single-crystal diamond epitaxial film 2 between the heavily doped regions was 1.2 GPa.

[0101] 4) The sample was first cleaned with inorganic and then with organic solvents, dried with nitrogen, and then placed in the cavity of a microwave plasma chemical vapor deposition (MPCVD) equipment. The microwave plasma power was controlled to maintain the chamber temperature at 700℃ and the hydrogen flow rate at 100 sccm. The grown single-crystal diamond epitaxial film 2 and the heavily doped N-type diamond film were hydrogenated for 25 min, resulting in a two-dimensional hole gas surface density of 3 × 10⁻⁶. 13 cm -2 The mobility is 1400 cm. 2 / V·s.

[0102] 5) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the source and drain electrode patterns. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, two metal layers, Pd and Au, were sequentially deposited on the sample surface, with thicknesses of 50 nm and 500 nm, respectively. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the source electrode 7 and the drain electrode 8.

[0103] 6) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then blow dry; spin-coat a layer of AZ5214 photoresist onto the sample surface, bake the single crystal diamond sample with photoresist on 95℃ for 90s, expose it to ultraviolet light for 4s using the designed mask, develop it for 30s to remove the exposed photoresist, leaving the channel region 4 as a protective pattern, and treat the sample with ultraviolet / ozone for 20min to transform the two sides of the channel region 4 into insulating isolation regions 5.

[0104] 7) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Place the sample in an atomic layer deposition (ALD) apparatus to deposit an Al2O3 dielectric layer on the sample surface. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the gate dielectric layer pattern. Then, wet-etch the Al2O3 dielectric layer to remove the photoresist and obtain the gate dielectric layer 6.

[0105] 8) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat a layer of AZ5214 photoresist onto the sample surface. Bake the single-crystal diamond sample with the photoresist coated at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the gate electrode pattern. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, Al and Au metals of 50 nm and 300 nm were deposited sequentially on the sample surface. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically peeled off to obtain the gate electrode 9, and finally a diamond-based field-effect transistor with high carrier mobility under stress was obtained.

[0106] Example 5

[0107] The present invention provides a method for fabricating a diamond field-effect transistor with enhanced carrier mobility, comprising the following steps:

[0108] 1) The diamond substrate 1 grown by high temperature and high pressure (HPHT) technology was subjected to inorganic and organic cleaning processes using the standard cleaning process of diamond substrate 1, and then dried with nitrogen gas for later use.

[0109] 2) A single-crystal diamond film was deposited on the cleaned diamond substrate 1 using microwave plasma chemical deposition (MPCVD). The plasma power was 1.5 kW, the chamber pressure was 100 Torr, and the total gas flow rate was 500 sccm. The resulting single-crystal diamond film had a thickness of 2 μm, a resistivity greater than 100 mΩ·cm, a root mean square surface roughness of 0.35 nm, and a Raman curve half-width of 1.6 cm. -1 The half-peak width of the XRD rocking curve is 22 arcsec.

[0110] 3) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the single-crystal diamond sample with the photoresist coated at 95℃ for 90s. Expose the sample to ultraviolet light using a pre-designed mask for 4s, and develop it for 30s to remove the exposed photoresist, leaving the pattern of the diffusion-doped region. Harden the remaining photoresist at 120℃ for 120s. Place the photolithographically patterned sample in a diffusion-doping device and deposit 99.999% pure phosphorus pentoxide powder onto the sample surface. Then, send the sample into an annealing furnace and perform a stepped heat treatment at 650℃ (30min), 1250℃ (60min), and 1450℃ (30min) in an oxygen atmosphere to complete the phosphorus diffusion process.

[0111] 4) The samples were sequentially cleaned with inorganic and organic solvents, dried with nitrogen, and placed in the microwave plasma chemical vapor deposition (MPCVD) chamber. The microwave plasma power was controlled to maintain the chamber temperature at 700℃ and the hydrogen flow rate at 80 sccm. The grown single-crystal diamond epitaxial film 2 and the heavily doped N-type diamond film were hydrogenated for 15 min, resulting in a two-dimensional hole gas surface density of 3 × 10⁻⁶. 13 cm -2 The mobility is 1200 cm. 2 / V·s.

[0112] 5) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the source and drain electrode patterns. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, two metal layers, Pd and Au, were sequentially deposited on the sample surface, with thicknesses of 50 nm and 500 nm, respectively. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically removed to obtain the source electrode 7 and the drain electrode 8.

[0113] 6) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then blow it dry; place the sample in the PECVD equipment and deposit a SiNx layer on the sample surface. The deposition conditions are as follows: the reaction gases are NH3 and SiH4, the carrier gas is an inert gas such as Ar, the SiH4 (diluted to 12% with N2) to NH3 gas flow ratio is 4, the deposition temperature is 300℃, the reaction pressure is 500mTorr, the RF power is 300W, and the frequency is 13.65MHz.

[0114] 7) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then blow dry. Spin-coat the sample surface with a layer of AZ5214 photoresist. Bake the spin-coated single-crystal diamond sample at 95℃ for 90s. Expose it to ultraviolet light using a pre-designed mask for 4s, followed by development for 30s to remove the exposed photoresist, leaving the dielectric layer to retain the pattern. Then, wet-etch the SiNx film using BOE buffer. Remove the etched diamond sample, immerse it in N-methylpyrrolidone (NMP) solution, and bathe it in a 120℃ water bath for 5min. Then, ultrasonically remove the photoresist from the sample surface to obtain the gate dielectric layer 6.

[0115] 8) Clean the sample with acetone, isopropanol, and deionized water using ultrasonic cleaning and then blow it dry; use the SiNx dielectric layer as a mask to treat the sample with oxygen plasma for 10 min at a power of 30W and an oxygen flow rate of 80sccm, so as to transform the two sides of the channel region 4 into the insulating isolation region 5.

[0116] 9) Clean the sample ultrasonically with acetone, isopropanol, and deionized water, and then dry it. Spin-coat a layer of AZ5214 photoresist onto the sample surface. Bake the spin-coated single-crystal diamond sample at 95°C for 90 seconds. Expose the sample to ultraviolet light using a pre-designed mask for 4 seconds, followed by development for 30 seconds to remove the exposed photoresist, leaving the gate electrode pattern. Place the photolithographically patterned sample in an electron beam evaporation apparatus and evacuate the background vacuum to 5 × 10⁻⁶. -4 After Pa, Al and Au metals of 50 nm and 300 nm were deposited sequentially on the sample surface. The deposited diamond sample was then removed, immersed in N-methylpyrrolidone (NMP) solution, and bathed in a 120°C water bath for 5 min. The metal outside the exposed area was then ultrasonically peeled off to obtain the gate electrode 9, and finally a diamond-based field-effect transistor with high carrier mobility under stress was obtained.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A carrier mobility enhanced diamond field effect transistor, characterized by, The diamond substrate (1), the single crystal diamond epitaxial film (2), the gate dielectric layer (6), the source electrode (7), the drain electrode (8) and the gate electrode (9) are included. The single crystal diamond epitaxial film (2) is arranged on the diamond substrate (1). The single crystal diamond epitaxial film (2) is provided with a first heavily doped diamond film region and a second heavily doped diamond film region; a hydrogen termination region is arranged on the surface of the first heavily doped diamond film region, the second heavily doped diamond film region and the single crystal diamond epitaxial film (2) between the two; and an oxygen termination region is arranged on the surface of the remaining single crystal diamond epitaxial film (2); wherein the hydrogen termination region is a channel region (4) composed of a two-dimensional hole gas conductive layer. The source electrode (7) and the drain electrode (8) are both arranged on the channel region (4). The source electrode (7), the drain electrode (8) and the channel region (4) therebetween are provided with the gate dielectric layer (6). The gate electrode (9) is arranged on the gate dielectric layer (6) and the oxygen termination region. The doping elements in the first heavily doped diamond film and the second heavily doped diamond film include one or more of boron, aluminum, phosphorus and nitrogen.

2. A diamond field effect transistor with enhanced carrier mobility according to claim 1, wherein The doping concentration of the first heavily doped diamond film and the second heavily doped diamond film is 10 19 cm -2 ~ 10 21 cm -2 , the resistivity is less than 100 mΩ·cm, the width is 10 μm~500 μm, the depth is 10 nm~5 μm, and the internal tensile stress is generated.

3. The carrier mobility enhanced diamond field effect transistor of claim 1, wherein, The material of the gate dielectric layer (6) is an insulating material.

4. The carrier mobility enhanced diamond field effect transistor of claim 1, wherein, The channel length of the channel region (4) is 20 nm to 100 μm, the carrier concentration in the channel is 5 x 1018 cm-3 to 5 x 1020 cm-3, and the mobility is 20 cm2 / V-s to 2500 cm2 / V-s. 12 cm -2 ~ 5 x 1020 cm 14 cm -2 -3, and the mobility is 20 cm2 / V-s to 2500 cm2 / V-s. 2 / V-s to 2500 cm2 / V-s. 2 / V-s to 2500 cm2 / V-s.

5. The carrier mobility enhanced diamond field effect transistor of claim 1, wherein, The steps include:

6. A method of fabricating a diamond field effect transistor having enhanced carrier mobility as claimed in claim 1, wherein, Step 1, cleaning and blowing dry the diamond substrate (1) to obtain a cleaned diamond substrate (1); Step 2, epitaxially growing a single crystal diamond film on the diamond substrate (1) obtained in step 1 to obtain a single crystal diamond epitaxial film (2); Step 3, forming a heavily doped diamond film (3) in a preset region of the single crystal diamond epitaxial film (2) obtained in step 2 to obtain a first heavily doped diamond film region and a second heavily doped diamond film region; Step 4, hydrogenating the surface of the single crystal diamond epitaxial film (2) to obtain a hydrogen termination region; and taking the hydrogen termination region on the surface of the first heavily doped diamond film region, the second heavily doped diamond film region and the single crystal diamond epitaxial film (2) therebetween as a channel region (4); Step 5, forming a source electrode and a drain electrode pattern on the channel region (4) above the first heavily doped diamond film region and the second heavily doped diamond film region respectively by using a photolithography technology, depositing a source electrode and a drain electrode metal, and obtaining an ohmic contact of a source electrode (7) and a drain electrode (8) by using a stripping technology; Step 6, depositing and forming a gate dielectric layer (6) on the source electrode (7), the drain electrode (8) and the channel region (4) therebetween; Step 7, using the gate dielectric layer (6) deposited in step 6 as a mask to perform an oxygen termination treatment to form an oxygen termination region; Step 8, forming a gate electrode pattern on the gate dielectric layer (6) and the oxygen termination region by using a photolithography technology, depositing a gate electrode metal, and obtaining a gate electrode (9). In step 3, the step of forming a heavily doped diamond film (3) in a preset region of the single crystal diamond epitaxial film (2) obtained in step 2 specifically includes:

7. The preparation method according to claim 6, characterized in that, ​ The preset area of the single-crystal diamond epitaxial film (2) obtained in step 2 is formed into a heavily doped diamond film (3) through etching and selective epitaxial growth, diffusion or ion implantation processes.

8. The preparation method according to claim 7, characterized in that, When the heavily doped diamond film (3) is formed through the etching and selective epitaxial growth processes, First, the single-crystal diamond epitaxial film (2) is subjected to ICP etching, with a radio frequency power of 200 W to 1000 W, a direct current power of 50 W to 300 W and an etching time of 30 s to 1800 s; then, selective epitaxial growth is performed, with a cavity temperature of 800 DEG C to 1200 DEG C and a cavity pressure of 3 kPa to 18 kPa.

9. The preparation method according to claim 7, characterized in that, When the heavily doped diamond film (3) is formed through the diffusion process, The compound of the doping substance is coated on the surface of the single-crystal diamond epitaxial film (2), and annealing is performed through staged temperature rising from 600 DEG C to 1800 DEG C with a variation range of 300 DEG C to 400 DEG C to form the heavy doping.

10. The preparation method according to claim 7, characterized in that, When the heavily doped diamond film (3) is formed through the ion implantation process, The ion energy is 20 keV to 1500 keV, and the implanted ion dose is 10 15 cm -2 ~ 10 20 cm -2 .

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