CN115863436A - Diamond field effect transistor and preparation method thereof - Google Patents

Abstract

The invention discloses a diamond field effect transistor and a preparation method thereof, wherein the diamond field effect transistor comprises: the device comprises a diamond substrate, a single crystal diamond epitaxial film, a source electrode, a drain electrode, a stress regulating film and a gate electrode; a monocrystalline diamond epitaxial film is arranged on the diamond substrate; a hydrogen terminal region and an oxygen terminal region are arranged on the monocrystalline diamond epitaxial film, and the hydrogen terminal region is a channel region formed by a two-dimensional hole gas conductive layer; an active electrode and a drain electrode are respectively arranged at two ends of the channel region; stress regulating films are arranged on the source electrode, the drain electrode and a channel region where the source electrode and the drain electrode are not arranged; the gate electrode is disposed on the stress regulating thin film and the oxygen termination region. The invention introduces a stress control film; based on the stress control film, the carrier mobility can be enhanced through stress control, and the performance of the conductive channel cannot be damaged.

Description

Diamond field effect transistor and preparation method thereof

Technical Field

The invention belongs to the technical field of semiconductor devices, and particularly relates to a diamond field effect transistor and a preparation method thereof.

Background

With the application of the first generation semiconductor materials silicon (Si) and germanium (Ge) in the field of electronic devices, human scientific and technological lives enter the motorway; under the drive of the technological progress and the development demand of integrated circuits, gallium arsenide (GaAs) which is a second-generation semiconductor material, silicon carbide (SiC) which is a third-generation semiconductor material, and gallium nitride (GaN) are also developed and utilized successively; moore's law requires more electronic devices to be integrated in a unit area, which leads to increasingly prominent problems of heat dissipation, gate breakdown, tunneling leakage current and the like of the devices, and people gradually turn their eyes to new semiconductor materials in order to solve the above problems.

Compared with other semiconductor materials, the diamond has wide forbidden band width, high mobility, large thermal conductivity, large Johnson, balia and Keyes quality factors; as shown in Table 1, the table 1 shows the comparison data of the quality factor of the diamond material with Si, gaN and SiC, and the electrical property of the diamond material is obviously superior to that of other third-generation semiconductor materials, so that the performance of the diamond-based electronic device is superior to that of other semiconductor electronic devices; meanwhile, the method covers the application fields of output power and working frequency to the maximum extent, and is very suitable for preparing ultrahigh-frequency, ultrahigh-power, high-temperature-resistant and anti-radiation electronic devices. Therefore, the method has great application potential in the fields of aerospace, advanced equipment and the like with very high requirements on material volume, weight, heat dissipation, power density and reliability.

TABLE 1 comparison data of diamond material quality factor with Si, gaN, siC

Material	Johnson index	Keyes index	Baliga index [ Si =1]
				Diamond	2530	145	43938
SiC	910	35	620
				GaN	756	104	870
Si	1	1	1

Experiments prove that electrons in the valence band of the diamond on the surface of the hydrogen terminal are transferred to the lowest unoccupied molecular orbital (LOMO) in adsorbed molecules, so that a layer of two-dimensional hole gas (2 DHG) is formed on the surface of the diamond, and 10 can be obtained ¹³ cm ^-2 The surface carrier concentration of the left and right, and 20-680cm ² ·V ^-1 ·s ^-1 The mobility of the current carrier in the range is theoretically predicted to be more than 3000cm after the problem of interface ionized impurity scattering and roughness scattering is solved ² ·V ^-1 ·s ^-1 。

When the traditional element doping is not solved, the two-dimensional hole gas can be used as a conductive channel of a field effect transistor, and the development of a diamond FET is greatly promoted; however, hydrogen-terminated diamond has a lower mobility due to the limited surface termination bond length, resulting in a lower transfer doping dipole moment, increasing channel carrier transport scattering. In recent years, the enhancement of the carrier mobility of a conductive channel on the surface of a hydrogen terminal diamond is realized by methods such as epitaxial high-quality diamond layer, amorphous carbon adsorption, introduction of high-dielectric constant material enhanced dielectric shielding and the like, but the actual enhancement effect is limited; the surface of the hydrogen terminal diamond can be passivated based on the two-dimensional material, so that the channel carrier mobility can be improved, such as h-BN, and the two-dimensional material can passivate the surface state of the hydrogen terminal diamond, and meanwhile, part of charges can be transferred on the outer surface of the two-dimensional material, so that the charge acting distance is increased, the surface scattering is reduced, and the carrier mobility is obviously improved; however, the two-dimensional material realized based on the lift-off technology cannot realize a large-size conductive channel, and is difficult to meet the actual application requirements, and other methods for improving mobility or new device structures need to be explored.

Disclosure of Invention

The present invention is directed to a diamond field effect transistor and a method for fabricating the same that solves one or more of the problems set forth above. According to the diamond field effect transistor, the stress regulation and control film is introduced; based on the stress control film, the carrier mobility can be enhanced through stress control, and the performance of the conductive channel cannot be damaged.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a diamond field effect transistor, comprising: the device comprises a diamond substrate, a single crystal diamond epitaxial film, a source electrode, a drain electrode, a stress regulating film and a gate electrode;

the single crystal diamond epitaxial film is arranged on the diamond substrate; a hydrogen terminal region and an oxygen terminal region are arranged on the monocrystalline diamond epitaxial film, and the hydrogen terminal region is a channel region formed by a two-dimensional hole gas conductive layer;

the source electrode and the drain electrode are respectively arranged at two ends of the channel region;

the stress regulating and controlling thin film is arranged on the source electrode, the drain electrode and a channel region where the source electrode and the drain electrode are not arranged, and the stress regulating and controlling thin film is used for regulating and controlling the stress of the single-crystal diamond epitaxial thin film and the channel region below the stress regulating and controlling thin film so as to improve the carrier mobility of the two-dimensional hole gas conductive layer;

the gate electrode is disposed on the stress control film and the oxygen termination region.

The invention is further improved in that the stress control film is made of SiN _x 、SiO ₂ 、Al ₂ O ₃ 、HfO ₂ 、ZrO ₂ Diamond-like carbon or a material having a work function of 5eV or more.

The invention has the further improvement that the thickness of the stress control film is 1 nm-5000 nm.

The invention has the further improvement that the internal pressure stress of the stress control film is 1 MPa-10 GPa.

The further improvement of the invention is that the magnitude of the compressive stress in the monocrystalline diamond epitaxial film below the stress control film is 10 MPa-5 GPa. .

The invention is further improved in that the width of the channel region is 5 nm-100 μm, and the carrier concentration in the channel is 1 × 10 ¹² cm ^-2 ～5×10 ¹⁴ cm ^-2 Mobility of 20cm ² /V·s～2500cm ² /V·s。

The further improvement of the invention is that the materials of the source electrode and the drain electrode are Au, pd, ir, pt or Ti; the gate electrode is made of Al, zr, hf or Mo.

The invention provides a preparation method of a diamond field effect transistor, which comprises the following steps:

homoepitaxy monocrystal diamond film on the cleaned diamond substrate to obtain monocrystal diamond epitaxial film;

carrying out hydrogenation treatment on the monocrystalline diamond epitaxial film to obtain a two-dimensional cavity gas conductive layer;

processing and forming source electrode and drain electrode patterns on the two-dimensional hole gas conductive layer, correspondingly depositing source electrode metal and drain electrode metal, and obtaining ohmic contact of the source electrode and the drain electrode by utilizing a stripping technology;

covering photoresist on a source electrode, a drain electrode and a channel region between the source electrode and the drain electrode, and performing oxygen terminal treatment by utilizing a photoetching technology to form an oxygen terminal region so as to realize electrical isolation of a device;

depositing a stress control film on the source electrode, the drain electrode and the channel region between the source electrode and the drain electrode; regulating the internal pressure stress of the stress regulating film to meet the preset requirement;

and processing to form a gate electrode pattern on the stress control film and the oxygen terminal area, and depositing gate electrode metal and then obtaining a gate electrode by utilizing a stripping technology.

In a further improvement of the present invention, in the step of depositing the stress control film on the source electrode, the drain electrode and the channel region therebetween,

the deposition mode adopts electron beam evaporation, sputtering, atomic layer deposition, plasma enhanced chemical vapor deposition or low-pressure vapor chemical deposition.

The invention is further improved in that in the step of regulating the internal pressure stress of the stress regulating film to meet the preset requirement,

the regulation and control mode adopts ion implantation, thermal annealing, multilayer deposition or ultraviolet ray-assisted heat treatment process.

Compared with the prior art, the invention has the following beneficial effects:

the technical scheme of the invention particularly provides a diamond field effect transistor with enhanced carrier mobility by stress regulation, wherein a stress regulation film is introduced, equivalent stress can be generated in a single crystal diamond epitaxial film and a channel region by utilizing high film stress, the effective mass of carriers is reduced, the interband scattering of the carriers is weakened, and the ionized impurity scattering at a diamond interface of the stress regulation film/hydrogen terminal is reduced, so that the mobility of the carriers in the channel is increased, and the electrical characteristics such as the speed of a diamond-based device, the current capacity in a conducting state, the conducting-disconnecting ratio and the like are improved; in addition, the invention can not damage the performance of the conductive channel, and the deposited stress regulating film can be used as a gate dielectric layer to reduce the leakage current of the gate.

The preparation method provided by the invention can improve the channel carrier mobility and improve the current transport capacity between the source and the drain on the premise of not damaging the concentration of two-dimensional hole gas carriers generated by the hydrogen terminal; the invention discloses a structure of a film stress control diamond-based field effect transistor, which has the advantages of simple process steps, compatible process, high reliability and stability and obvious effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a schematic cross-sectional structural diagram of a stress-controlled carrier mobility-enhanced diamond field effect transistor according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a top view of a diamond field effect transistor in an embodiment of the present invention;

fig. 3 is a schematic flow chart of a method for manufacturing a diamond field effect transistor with enhanced carrier mobility by stress control according to an embodiment of the present invention;

in the figure, 1, a diamond substrate; 2. a single crystal diamond epitaxial film; 3. a source electrode; 4. a drain electrode; 5. a channel region; 6. a stress control film; 7. a gate electrode; 8. an oxygen termination region.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1 and fig. 2, a diamond field effect transistor, specifically a diamond field effect transistor with enhanced carrier mobility by stress control, according to an embodiment of the present invention includes: the device comprises a diamond substrate 1, a single crystal diamond epitaxial film 2, a source electrode 3, a drain electrode 4, a channel region 5, a stress control film 6, a gate electrode 7 and an oxygen terminal region 8; wherein, a layer of monocrystalline diamond epitaxial film 2 is arranged on the diamond substrate 1; a channel region 5 is arranged on the monocrystalline diamond epitaxial film 2; a source electrode 3 and a drain electrode 4 are provided on the channel region 5; the channel region 5 is a hydrogen termination; a layer of stress regulating film 6 is arranged on the source electrode 3, the drain electrode 4 and the channel region 5; the gate electrode 7 is provided on the stress regulating film 6. Specifically illustratively, the channel region 5 is a hydrogen termination, and the channel region 5 includes a two-dimensional hole gas conducting layer in which carriers can migrate.

Specifically, the diamond substrate 1 is prepared by adopting a high-temperature high-pressure HPHT technology, a large-area splicing technology and a vapor phase epitaxy CVD technology and is used as a base; on which the single crystal diamond epitaxial film 2 is homoepitaxially obtained.

In the embodiment of the invention, the thickness of the stress control film 6 is 1 nm-5000 nm, and the stress film material is a dielectric material including but not limited to SiN _x 、SiO ₂ 、Al ₂ O ₃ 、HfO ₂ 、ZrO ₂ Diamond-like carbon, high work function materials (work function greater than or equal to 5 eV); the internal pressure stress of the film is 1 MPa-10 GPa. As specific examples, the stress control film 6 may be deposited by electron beam evaporation, sputtering, atomic Layer Deposition (ALD), plasma Enhanced Chemical Vapor Deposition (PECVD), low pressure vapor chemical deposition (LPCVD), and the like, and may have a thickness of 1nm to 5000nm, including but not limited to SiN _x 、SiO ₂ 、Al ₂ O ₃ 、HfO ₂ 、ZrO ₂ High work function material, ion implantation technology, thermal annealing and multi-layer depositionThe stress regulating film 6 is processed by technologies such as ultraviolet ray auxiliary heat treatment and the like, and finally high-pressure stress is formed in the film, wherein the magnitude of the pressure stress is 1 MPa-10 GPa.

Specifically, the single crystal diamond epitaxial film 2 is a CVD grown diamond material in which a compressive stress is generated, the stress is 10MPa to 5GPa, the resistivity is greater than 100M Ω · cm, the root mean square surface roughness is less than 0.5nm, and the raman curve half-peak width is less than 2cm ^-1 The half-peak width of an XRD rocking curve is less than 30arcsec; carrying out hydrogenation treatment on the surface of the substrate to generate a layer of two-dimensional hole gas which is used as a conducting channel of the field effect transistor. The channel region 5 is a transistor conduction channel, comprises the two-dimensional hole gas conductive layer, and carrier holes can move in the channel region, the width of the channel region 5 is 5 nm-100 μm, and the carrier concentration in the channel is 1 × 10 ¹² cm ^-2 ～5×10 ¹⁴ cm ^-2 Mobility of 20cm ² /V·s～2500cm ² /V·s。

Specifically, the coverage area of the stress control film 6 includes, but is not limited to, the source electrode 3, the drain electrode 4, and the channel region 5; the source electrode 3 and the drain electrode 4 are made of Au, pd, ir, pt or Ti and the like, and form good ohmic contact with the hydrogen terminal diamond; the gate electrode 7 is made of metal such as Al, zr, hf, or Mo.

Referring to fig. 3, a method for manufacturing a diamond field effect transistor with enhanced carrier mobility by stress control according to an embodiment of the present invention includes the following steps:

step 1, cleaning a diamond substrate 1 and drying the diamond substrate;

step 2, homoepitaxially growing a single crystal diamond film on the diamond substrate 1 to obtain a single crystal diamond epitaxial film 2;

step 3, carrying out hydrogenation treatment on the monocrystalline diamond epitaxial film 2 to obtain a layer of two-dimensional cavity gas conductive layer, namely a channel region 5;

step 4, cleaning the single crystal diamond epitaxial film 2 after hydrogenation treatment, forming a source and drain electrode pattern on the surface of the single crystal diamond epitaxial film by utilizing a photoetching technology, depositing source and drain electrode metal, and obtaining ohmic contact between a source electrode 3 and a drain electrode 4 by utilizing a stripping technology;

step 5, covering photoresist on the source and drain electrodes and the hydrogen terminal diamond between the source and drain electrodes by utilizing a photoetching technology, and carrying out oxygen terminal treatment to convert the exposed hydrogen terminal diamond into the oxygen terminal diamond to form an oxygen terminal area 8, thereby realizing the electrical isolation of the device;

step 6, depositing the stress control film 6 on the source electrode 3, the drain electrode 4 and the hydrogen terminal channel region 5 by using deposition modes such as electron beam evaporation, sputtering, atomic Layer Deposition (ALD), plasma Enhanced Chemical Vapor Deposition (PECVD), low-pressure vapor chemical deposition (LPCVD) and the like;

step 7, processing the stress regulating film 6 by means of ion implantation, thermal annealing, multilayer deposition technology, ultraviolet ray assisted thermal treatment and the like to regulate the stress;

and 8, forming a gate electrode pattern on the channel region 5 by utilizing a photoetching technology, depositing gate electrode metal, and obtaining a gate electrode 7 by utilizing a stripping technology.

The single crystal diamond epitaxial film 2 obtained in the step 2 of the embodiment of the invention is a CVD grown diamond material, and the pressure stress is generated in the single crystal diamond epitaxial film 2, the stress is 10 MPa-5 GPa, the resistivity is more than 100M omega cm, the root-mean-square surface roughness is less than 0.5nm, and the Raman curve half-peak width is less than 2cm ^-1 And the half-peak width of an XRD rocking curve is less than 30arcsec.

In the step 3 of the embodiment of the invention, the hydrogenation treatment is to place the diamond sample in hydrogen plasma or hydrogen atmosphere, the treatment temperature is 700-1000 ℃, and the treatment time is 10 s-2 h. The width of the hydrogen termination channel region 5 is 5nm to 100 μm, and the carrier concentration in the channel is 1X 10 ¹² cm ^-2 ～5×10 ¹⁴ cm ^-2 Mobility of 20cm ² /V·s～2500cm ² /V·s。

The step 5 of the embodiment of the invention specifically comprises the following steps of: and treating the surface of the monocrystalline diamond epitaxial film 2 by using ultraviolet rays or/and ozone and oxygen plasmas, wherein the gas flow of the oxygen or the ozone is 1 sccm-100 sccm, the plasma power is 100W-300W, and the treatment time is 1 min-60 min.

In step 6 of the embodiment of the invention, the deposition temperature of PECVD is 200-370 ℃, siH ₄ And NH ₃ The gas flow ratio is 2-4, the reaction pressure is 400 mTorr-500 mTorr, and the power source frequency is 20W-500W; the deposition temperature of LPCVD is 600-1000 deg.C, siH ₂ Cl ₂ And NH ₃ The gas flow ratio is 5-10, the reaction pressure is 100 mTorr-300 mTorr, and the power source frequency is 20W-500W; the deposition temperature of ALD is 100-400 ℃, the background is vacuumized by 2-10 multiplied by 10 ^-5 Pa, the flow rate of the carrier gas is 100 sccm-400 sccm; the heating temperature of electron beam evaporation is 20-1000 ℃, and the background is vacuumized by 2-10 multiplied by 10 ^{- 5} Pa, the electric field intensity is 5kV to 10kV, and the power of the electron gun is 1kW to 5kW; the heating temperature of the base material for sputtering is 20-1000 ℃, and the vacuum pumping of the background is 2-10 multiplied by 10 ^-5 Pa, the bias voltage of the base material is 0V to-500V, and the power supply is 50W to 2000W.

In step 7 of the embodiment of the present invention, the ion implanted by the ion implantation technique is P ⁺ ，As ⁺ ，Sb ⁺ ，BF ₂ ⁺ Etc., which can regulate and control the film stress; the annealing temperature of the annealing process is 100-1200 ℃, and the annealing time is 5 s-2 h; the processing temperature of the ultraviolet auxiliary heat treatment is 100-500 ℃, the processing time is 5 s-30 min, and the internal pressure stress of the film is 1 MPa-10 GPa.

The lithography techniques in step 4 and step 8 of the embodiment of the present invention include ultraviolet lithography, electron beam lithography, and step-by-step non-contact lithography.

In summary, the diamond field effect transistor with enhanced carrier mobility controlled by stress provided by the embodiment of the invention includes a diamond substrate, a single crystal diamond epitaxial film, a source electrode, a drain electrode, a channel region (hydrogen terminal), a stress control film, a gate electrode and an oxygen terminal region; wherein, a layer of monocrystalline diamond epitaxial film is arranged on the diamond substrate; a channel region is arranged on the monocrystalline diamond epitaxial film; a source electrode and a drain electrode are arranged on the channel region; the channel region is a hydrogen terminal and comprises a two-dimensional hole gas conductive layer, and current carriers can migrate in the channel; a layer of stress regulating film is arranged on the source electrode, the drain electrode and the channel region; the gate electrode is disposed on the stress modulating film. According to the invention, the channel carrier mobility is regulated by adopting film stress, equivalent stress can be generated in a single-crystal diamond epitaxial film and a channel region by utilizing high film stress, the asymmetry of a single-crystal diamond crystal is changed under the action of the stress, and energy level splitting is generated, so that on one hand, the number of carriers in a low energy level is increased, the carriers have smaller effective mass, on the other hand, the separation of light and heavy holes can also weaken the interband scattering of the carriers, the scattering relaxation time is increased, the effective mass (m) is reduced according to a mobility formula mu = q tau/m, the scattering relaxation time (tau) is increased, and the carrier mobility can be improved; meanwhile, the ionized impurity scattering at the diamond interface of the stress control film/hydrogen terminal can be reduced, so that the mobility of current carriers in a channel is further improved, and the electrical properties of the diamond-based device, such as speed, current capacity in a conducting state, conducting-disconnecting ratio and the like, are improved; the invention can improve the performance of the conductive channel by enhancing the carrier mobility, further improve the electrical characteristics of the transistor device, and simultaneously, the deposited stress control film can be used as a gate dielectric layer to reduce the leakage current of the gate.

Example 1

The embodiment of the invention provides a preparation method of a diamond field effect transistor for enhancing carrier mobility through stress regulation, which comprises the following steps:

1) And (3) carrying out inorganic and organic cleaning on the diamond substrate grown by the high-temperature high-pressure (HPHT) technology by using a standard cleaning process of the diamond substrate, and drying the diamond substrate by using nitrogen for later use.

2) Depositing a single crystal diamond film on the cleaned diamond substrate by using a microwave plasma gas phase chemical deposition (MPCVD) technology, wherein the plasma power is 1kW, the chamber pressure is 100Torr, the total gas flow is 500sccm, the thickness of the obtained single crystal diamond film is 1 μ M, the resistivity is 100 MOmega-cm, the root mean square surface roughness is 0.45nm, and the half-peak width of a Raman curve is 1.9cm ^-1 The half-peak width of the XRD rocking curve is 29arcsec.

3) Controlling the power of the microwave plasma to make the temperature of the chamber 900 ℃, keeping the hydrogen flow at 50sccm, and carrying out the growth of the single crystalThe diamond epitaxial film is hydrogenated for 5min to obtain a two-dimensional cavity gas surface density of 2 multiplied by 10 ¹³ cm ^-2 Mobility of 150cm ² /V·s。

4) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s, removing the exposed photoresist, and leaving a source and drain electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 After Pa, a layer of Au with the thickness of 200nm is deposited on the surface of the sample. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, and ultrasonically stripping off the metal outside the exposed area to obtain a source electrode and a drain electrode.

5) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of AZ5214 photoresist on the source and drain electrodes and the hydrogen terminal diamond between the source and drain electrodes, baking a single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, then processing the sample for 15min by using UV/Ozone equipment to convert the exposed hydrogen terminal diamond into the oxygen terminal diamond, thereby realizing the electrical isolation of the device, ensuring that the hydrogen terminal diamond only exists in the source and drain electrodes and a channel part between the source and drain electrodes, and finally removing the photoresist on the surface of the sample by using acetone.

6) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. Spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s, removing the exposed photoresist, and leaving a stress control film pattern. And depositing a 52nm silicon oxide stress control film on the source and drain electrodes and the hydrogen terminal diamond between the source and drain electrodes by using a magnetron Sputtering (SD) technology. The magnetron sputtering conditions are as follows: the power is 50W, the cavity pressure is 0.5Pa, the Ar flow is 30sccm, and the time is 15min. The sputtered target material is a silicon oxide target material with the purity of 99.9 percent.

7) Using an ion implanterImplanting P ⁺ Ions having an ion energy of 40keV and an ion concentration of 2X 10 ¹⁶ cm ^-2 . And stripping the photoresist to obtain a designed stress control film pattern. And then, carrying out an annealing process, wherein the annealing temperature is 900 ℃, and the annealing time is 30s. The compressive stress of the silicon oxide film after treatment is 1GPa, the compressive stress of the lower channel region and the epitaxial film of the monocrystalline diamond is 0.8GPa, and the carrier mobility of the channel is 1000cm ² /V·s。

8) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. Spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, and developing for 30s to remove the exposed photoresist and leave a gate electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 And after Pa, depositing Al metal of 50nm and Au metal of 100nm on the surface of the sample. And taking out the diamond sample after deposition, soaking the diamond sample in N-methyl pyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, and then ultrasonically stripping off metal outside an exposure area to obtain a gate electrode, thereby finally obtaining the prepared field effect transistor of the diamond with the stress regulation and control enhanced carrier mobility.

Example 2

The embodiment of the invention provides a preparation method of a diamond field effect transistor for enhancing carrier mobility through stress regulation and control, which comprises the following steps:

1) And (3) carrying out inorganic and organic cleaning on the diamond substrate grown by the CVD technology by using a standard cleaning process of the diamond substrate, and drying the diamond substrate by using nitrogen for later use.

2) Depositing a single crystal diamond film on the cleaned diamond substrate by using a microwave plasma gas phase chemical deposition (MPCVD) technology, wherein the plasma power is 1.2kW, the chamber pressure is 100Torr, the total gas flow is 500sccm, the thickness of the obtained single crystal diamond film is 2 mu M, the resistivity is 120 MOmega-cm, the root mean square surface roughness is 0.4nm, and the half-peak width of a Raman curve is 1.8cm ^-1 The half-peak width of the XRD rocking curve is 28arcsec.

3) Controlling microwave plasma power so that the cavity is closedThe room temperature is 700 ℃, the hydrogen flow is kept at 100sccm, the grown monocrystalline diamond epitaxial film is subjected to hydrogenation treatment for 20min, and the two-dimensional cavity gas surface density is 1 multiplied by 10 ¹³ cm ^-2 Mobility of 180cm ² /V·s。

4) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of KXN5735-LO photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, performing ultraviolet lithography exposure for 2s by using a designed mask, and developing for 25s to remove the unexposed photoresist, thereby leaving a source and drain electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 After Pa, a layer of Ti metal with the thickness of 20nm and Au metal with the thickness of 100nm are deposited on the surface of the sample. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, then ultrasonically stripping off metal outside an exposure area to obtain a source electrode and a drain electrode, and annealing the source electrode and the drain electrode at 500 ℃ for 3min in a nitrogen atmosphere to form excellent ohmic contact.

5) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of KXN5735-LO photoresist on the source and drain electrodes and the hydrogen terminal diamond between the source and drain electrodes, baking a single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, then treating the sample for 3min by using oxygen plasma equipment, wherein the power is 50W and the oxygen flow is 100sccm, so that the exposed hydrogen terminal diamond is converted into the oxygen terminal diamond, thereby realizing the electrical isolation of the device, ensuring that the hydrogen terminal diamond only exists in the channel part between the source and drain electrodes and the hydrogen terminal diamond, and finally removing the photoresist on the surface of the sample by using acetone.

6) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. A 45nm silicon nitride stress modulating film was deposited on the source and drain electrodes and the hydrogen-terminated diamond therebetween using a plasma enhanced chemical vapor deposition station (PECVD). The plasma enhanced chemical vapor deposition conditions were: the reaction gas being NH ₃ And SiH ₄ The carrier gas is inert gas such as Ar, siH ₄ (with N) ₂ Diluted to 12%) with NH ₃ The gas flow ratio was 2, the deposition temperature was 350 ℃, the reaction pressure was 500mTorr, the radio frequency power was 300W, and the frequency was 13.65MHz.

7) And carrying out ultraviolet exposure treatment on the film in an ultraviolet auxiliary heat treatment device, wherein the heat treatment temperature is 400 ℃, and the heat treatment time is 5min. The compressive stress of the processed silicon nitride film is 1.5GPa, the compressive stress of the lower channel region and the epitaxial film of the monocrystalline diamond is 1.2GPa, and the carrier mobility of the channel is 1200cm ² /V·s。

8) Spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s to remove the exposed photoresist, and leaving a stress control film protection pattern. And then, etching the silicon nitride film by using a BOE buffer solution wet method to obtain a designed stress control film pattern.

9) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. Spin-coating a layer of KXN5735-LO photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, performing ultraviolet lithography exposure for 2s by using a designed mask, and developing for 25s to remove the unexposed photoresist, thereby leaving a gate electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 After Pa, au metal is deposited on the surface of the sample by 100nm. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, then ultrasonically stripping off metal outside an exposure area to obtain a gate electrode, and finally obtaining the prepared diamond field effect transistor with the stress regulation and control enhanced carrier mobility.

Example 3

The embodiment of the invention provides a preparation method of a diamond field effect transistor for enhancing carrier mobility through stress regulation and control, which comprises the following steps:

1) And (3) carrying out inorganic and organic cleaning on the diamond substrate grown by the CVD technology by using a standard cleaning process of the diamond substrate, and drying the diamond substrate by using nitrogen for later use.

2) Using microwaves or the likeDepositing a monocrystalline diamond film on the cleaned diamond substrate by using a plasma vapor phase chemical deposition (MPCVD) technology, wherein the plasma power is 1kW, the chamber pressure is 100Torr, the total gas flow is 500sccm, the thickness of the obtained monocrystalline diamond film is 2 mu M, the resistivity is 120 MOmega-cm, the root-mean-square surface roughness is 0.4nm, and the half-peak width of a Raman curve is 1.8cm ^-1 The half-width of the XRD rocking curve is 25arcsec.

3) Controlling microwave plasma power to make chamber temperature 900 deg.C, keeping hydrogen flow at 50sccm, hydrogenating the grown single crystal diamond epitaxial film for 5min to obtain two-dimensional cavity gas surface density of 2 × 10 ¹³ cm ^-2 Mobility of 150cm ² /V·s。

4) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s, removing the exposed photoresist, and leaving a source and drain electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 After Pa, a layer of 100nm thick Pd metal was deposited on the sample surface. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, and then ultrasonically stripping off the metal outside the exposed area to obtain a source electrode and a drain electrode.

5) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. A stress modulating film of 90nm was deposited on the source and drain electrodes and the hydrogen-terminated diamond therebetween using a low pressure chemical vapor deposition station (LPCVD). The low-pressure chemical vapor deposition conditions are as follows: the reaction gas being NH ₃ And SiH ₂ Cl ₂ The carrier gas is inert gas such as Ar, siH ₂ Cl ₂ And NH ₃ The gas flow ratio was 8, the deposition temperature was 850 deg.C, and the reaction pressure was 150mTorr.

6) And carrying out ultraviolet exposure treatment on the film in an ultraviolet auxiliary heat treatment device, wherein the heat treatment temperature is 400 ℃, and the heat treatment time is 5min. The compressive stress of the processed silicon nitride film is 0.7GPaThe compressive stress of the lower channel region and the epitaxial film of the single crystal diamond is 0.6GPa, and the carrier mobility of the channel is 800cm ² /V·s。

7) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of AZ5214 photoresist on the source and drain electrodes and the hydrogen terminal diamond between the source and drain electrodes, baking a single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s to remove the exposed photoresist, leaving a stress control film protection pattern, then corroding the silicon nitride film by using a BOE buffer solution wet method to obtain a designed stress control film pattern, and removing the photoresist. And (3) using the stress control film as a mask, and treating the sample for 15min by using UV/Ozone equipment to convert the exposed hydrogen terminal diamond into the oxygen terminal diamond, thereby realizing the electrical isolation of the device and ensuring that the hydrogen terminal diamond only exists in the source electrode, the drain electrode and a channel part between the source electrode and the drain electrode.

8) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. Spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, and developing for 45s to remove the exposed photoresist and leave a gate electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 After Pa, au metal is deposited on the surface of the sample by 150nm. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, then ultrasonically stripping off metal outside an exposure area to obtain a gate electrode, and finally obtaining the prepared diamond field effect transistor with the stress regulation and control enhanced carrier mobility.

Example 4

The embodiment of the invention provides a preparation method of a diamond field effect transistor for enhancing carrier mobility through stress regulation, which comprises the following steps:

1) And (3) carrying out inorganic and organic cleaning on the diamond substrate grown by the high-temperature high-pressure (HPHT) technology by using a standard cleaning process of the diamond substrate, and drying the diamond substrate by using nitrogen for later use.

2) Depositing a single crystal diamond film on the cleaned diamond substrate by using a microwave plasma gas phase chemical deposition (MPCVD) technology, wherein the plasma power is 1kW, the chamber pressure is 100Torr, the total gas flow is 500sccm, the thickness of the obtained single crystal diamond film is 1 μ M, the resistivity is 100 MOmega-cm, the root mean square surface roughness is 0.35nm, and the half-peak width of a Raman curve is 1.5cm ^-1 The half-peak width of the XRD rocking curve is 25arcsec.

3) And controlling the power of the microwave plasma to enable the temperature of the cavity to be 700 ℃, keeping the hydrogen flow to be 50sccm, and carrying out hydrogenation treatment on the grown monocrystalline diamond epitaxial film for 20min to obtain the two-dimensional hole gas conductive layer.

4) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of KXN5735-LO photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, performing ultraviolet lithography exposure for 2s by using a designed mask, and developing for 25s to remove the unexposed photoresist, thereby leaving a source and drain electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 After Pa, a layer of Au metal with the thickness of 100nm is deposited on the surface of the sample. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, and ultrasonically stripping off the metal outside the exposed area to obtain a source electrode and a drain electrode.

5) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of KXN5735-LO photoresist on a source and drain electrode and a hydrogen terminal diamond between the source and drain electrodes, baking a single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, then treating the sample for 5min by using an oxygen plasma device, wherein the power is 30W and the oxygen flow is 80sccm, so that the exposed hydrogen terminal diamond is converted into an oxygen terminal diamond, thereby realizing the electrical isolation of a device, ensuring that the hydrogen terminal diamond only exists in the source and drain electrodes and a channel part between the source and drain electrodes, and finally removing the photoresist on the surface of the sample by using acetone.

6) The samples were ultrasonically cleaned using acetone, isopropyl alcohol, deionized water, and blown dry. Spin coating the sample surfaceBaking a monocrystalline diamond sample spin-coated with the photoresist for 90s at 95 ℃, performing ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s, removing the exposed photoresist, and leaving a stress control film pattern. A 150nm aluminum oxide film was deposited on the source and drain electrodes and the hydrogen-terminated diamond therebetween using electron beam evaporation physical vapor deposition (EB-PVD). The electron beam evaporation physical vapor deposition conditions are as follows: background vacuum degree of 3.7 × 10 ^-5 Pa, electron beam intensity of 5A, evaporation chamber pressure of 2 × 10 ^-2 Pa. The target material adopts alumina particles with the purity of 99 percent. And obtaining a designed stress control film pattern after stripping.

7) And then carrying out an annealing process, wherein the annealing temperature is 900 ℃, and the annealing time is 2h. The compressive stress of the processed alumina film is 0.8GPa, the compressive stress of the lower channel region and the epitaxial film of the monocrystalline diamond is 0.6GPa, and the carrier mobility of the channel is 900cm ² /V·s。

8) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. Spin-coating a layer of KXN5735-LO photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, performing ultraviolet lithography exposure for 2s by using a designed mask, and developing for 25s to remove the unexposed photoresist, thereby leaving a gate electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 And after Pa, depositing Al metal on the surface of the sample by 300nm. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, then ultrasonically stripping off metal outside an exposure area to obtain a gate electrode, and finally obtaining the prepared field effect transistor of the diamond with the stress regulation and control enhanced carrier mobility.

Example 5

The embodiment of the invention provides a preparation method of a diamond field effect transistor for enhancing carrier mobility through stress regulation, which comprises the following steps:

1) And (3) sequentially carrying out inorganic and organic cleaning on the diamond substrate grown by the high-temperature high-pressure (HPHT) technology by using a standard cleaning process of the diamond substrate, and drying the diamond substrate by using nitrogen for later use.

2) Depositing a single crystal diamond film on the cleaned diamond substrate by using a microwave plasma gas phase chemical deposition (MPCVD) technology, wherein the plasma power is 1kW, the chamber pressure is 100Torr, the total gas flow is 500sccm, the thickness of the obtained single crystal diamond film is 3 mu M, the resistivity is 110 MOmega-cm, the root-mean-square surface roughness is 0.3nm, and the half-peak width of a Raman curve is 1.7cm ^-1 The half-peak width of the XRD rocking curve is 25arcsec.

3) And controlling the power of the microwave plasma to ensure that the temperature of the cavity is 800 ℃, keeping the hydrogen flow rate at 100sccm, and carrying out hydrogenation treatment on the grown monocrystalline diamond epitaxial film for 30min to obtain the two-dimensional cavity gas conductive layer.

4) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, performing ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s to remove the unexposed photoresist, and leaving a source and drain electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 After Pa, a layer of Au metal with the thickness of 100nm is deposited on the surface of the sample. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, and ultrasonically stripping off the metal outside the exposed area to obtain a source electrode and a drain electrode.

5) Ultrasonically cleaning a sample by using acetone, isopropanol and deionized water, and drying; spin-coating a layer of AZ5214 photoresist on the source and drain electrodes and the hydrogen terminal diamond between the source and drain electrodes, baking a single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, then processing the sample for 15min by using UV/Ozone equipment to convert the exposed hydrogen terminal diamond into the oxygen terminal diamond, thereby realizing the electrical isolation of the device, ensuring that the hydrogen terminal diamond only exists in the source and drain electrodes and a channel part between the source and drain electrodes, and finally removing the photoresist on the surface of the sample by using acetone.

6) The samples were ultrasonically cleaned with acetone, isopropanol, deionized water and blown dry. Hydrogen termination between source and drain electrodes using Atomic Layer Deposition (ALD)And depositing a 300nm hafnium oxide film on the end diamond. The reaction gas comprises Hf (NMe) ₂ ) ₄ And pure water, the carrier gas comprising nitrogen, and a deposition temperature of 350 deg.C.

7) And then carrying out an annealing process, wherein the annealing temperature is 800 ℃, and the annealing time is 1h. The compressive stress of the hafnium oxide film after treatment is 2GPa, the compressive stress of the lower channel region and the monocrystalline diamond epitaxial film is 1.8GPa, and the channel carrier mobility is 1600cm ² V.s. Spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s to remove the exposed photoresist, and leaving a stress control film protection pattern. And finally, corroding the hafnium oxide film by a wet method to obtain a designed stress control film pattern.

8) The samples were ultrasonically cleaned using acetone, isopropyl alcohol, deionized water, and blown dry. Spin-coating a layer of AZ5214 photoresist on the surface of a sample, baking the single crystal diamond sample spin-coated with the photoresist for 90s at 95 ℃, carrying out ultraviolet lithography exposure for 4s by using a designed mask, developing for 30s, removing the unexposed photoresist, and leaving a gate electrode pattern. Placing the photoetched sample in an electron beam evaporation device, and vacuumizing the background to 5 x 10 ^-4 And after Pa, depositing Al metal of 100nm and Au metal of 150nm on the surface of the sample. And taking out the diamond sample after deposition, soaking the diamond sample in N-methylpyrrolidone (NMP) solution, carrying out water bath at 120 ℃ for 5min, then ultrasonically stripping off metal outside an exposure area to obtain a gate electrode, and finally obtaining the prepared field effect transistor of the diamond with the stress regulation and control enhanced carrier mobility.

Finally, it should be noted that: although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.

Claims (10)

1. A diamond field effect transistor, comprising: the device comprises a diamond substrate (1), a single crystal diamond epitaxial film (2), a source electrode (3), a drain electrode (4), a stress regulating film (6) and a gate electrode (7);

the single crystal diamond epitaxial film (2) is arranged on the diamond substrate (1); a hydrogen terminal region and an oxygen terminal region (8) are arranged on the monocrystalline diamond epitaxial film (2), and the hydrogen terminal region is a channel region (5) formed by a two-dimensional hole gas conductive layer;

the source electrode (3) and the drain electrode (4) are respectively arranged at two ends of the channel region (5);

the stress regulating and controlling thin film (6) is arranged on the source electrode (3), the drain electrode (4) and the channel region (5) without the source electrode and the drain electrode, and the stress regulating and controlling thin film (6) is used for regulating and controlling the stress of the single-crystal diamond epitaxial thin film (2) and the channel region (5) below the stress regulating and controlling thin film to improve the carrier mobility of the two-dimensional hole gas conductive layer;

the gate electrode (7) is disposed on the stress control film (6) and the oxygen termination region (8).

2. A diamond FET as claimed in claim 1, characterized in that said stress control film (6) is made of SiN _x 、SiO ₂ 、Al ₂ O ₃ 、HfO ₂ 、ZrO ₂ Diamond-like carbon or a material having a work function of 5eV or more.

3. A diamond field effect transistor according to claim 1, characterized in that the thickness of the stress control film (6) is 1nm to 5000nm.

4. The diamond FET according to claim 1, wherein the magnitude of the internal pressure stress of the stress control film (6) is 1 MPa-10 GPa.

5. A diamond field effect transistor according to claim 1, characterized in that the magnitude of the compressive stress in the monocrystalline diamond epitaxial film (2) below the stress control film (6) is 10 MPa-5 GPa.

6. A diamond fet as claimed in claim 1, characterised in that the channel region (5) has a width of 5nm to 100 μm and a channel carrier concentration of 1 x 10 ¹² cm ^-2 ～5×10 ¹⁴ cm ^-2 Mobility of 20cm ² /V·s～2500cm ² /V·s。

7. A diamond field effect transistor according to claim 1, characterized in that the source electrode (3) and the drain electrode (4) are made of Au, pd, ir, pt or Ti; the gate electrode (7) is made of Al, zr, hf or Mo.

8. A method of fabricating a diamond field effect transistor according to claim 1, comprising the steps of:

homoepitaxially growing a single crystal diamond film on the cleaned diamond substrate (1) to obtain a single crystal diamond epitaxial film (2);

carrying out hydrogenation treatment on the monocrystalline diamond epitaxial film (2) to obtain a two-dimensional cavity gas conductive layer;

processing and forming source electrode and drain electrode patterns on the two-dimensional hole gas conductive layer, correspondingly depositing source electrode metal and drain electrode metal, and obtaining ohmic contact of a source electrode (3) and a drain electrode (4) by utilizing a stripping technology;

covering photoresist on the source electrode (3), the drain electrode (4) and a channel region (5) between the source electrode and the drain electrode, and performing oxygen terminal treatment by utilizing a photoetching technology to form an oxygen terminal region (8) so as to realize electrical isolation of a device;

depositing a stress control film (6) on the source electrode (3), the drain electrode (4) and a channel region (5) between the source electrode and the drain electrode; regulating the internal pressure stress of the stress regulating film (6) to meet the preset requirement;

and processing and forming a gate electrode (7) pattern on the stress control film (6) and the oxygen terminal area (8), and obtaining the gate electrode (7) by utilizing a stripping technology after depositing gate electrode metal.

9. A method for preparing a diamond field effect transistor according to claim 8, wherein in the step of depositing the stress control film (6) on the source electrode (3), the drain electrode (4) and the channel region (5) therebetween,

the deposition mode adopts electron beam evaporation, sputtering, atomic layer deposition, plasma enhanced chemical vapor deposition or low-pressure vapor chemical deposition.

10. The method for preparing a diamond field effect transistor according to claim 8, wherein in the step of regulating the internal pressure stress of the stress regulating film (6) to meet a preset requirement,

the regulation and control mode adopts ion implantation, thermal annealing, multilayer deposition or ultraviolet ray-assisted heat treatment process.

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