MOS-HEMT device based on diamond / aluminum nitride polarization interface two-dimensional electron gas effect and preparation method thereof

Abstract

The invention relates to the technical field of integrated circuit manufacturing, in particular to a MOS-HEMT (Metal Oxide Semiconductor-High Electron Mobility Transistor) device based on a diamond / aluminum nitride polarization interface two-dimensional electron gas effect and a preparation method of the MOS-HEMT device. The AlN layer is deposited on the surface of the diamond substrate; the gate oxide dielectric layer is deposited on the surface of the AlN layer; the gate metal layer is formed on the surface of the gate oxide dielectric layer; and the source electrode layer and the drain electrode layer are respectively deposited on the surface of the diamond substrate and are positioned at two ends of the gate oxide dielectric layer and the AlN layer. According to the MOS-HEMT device, a heterostructure is constructed between the AlN thin film layer and the diamond, high-mobility two-dimensional electron gas (2DEG) is formed, the AlN thin film layer and the diamond form a polarization surface, and n-type electric conduction of the diamond is achieved. Therefore, the diamond-based power device has a wider development prospect, and a solid foundation is laid for a next-generation high-performance power device.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to a MOS-HEMT device based on a diamond / aluminum nitride polarization interface two-dimensional electron gas effect and a preparation method thereof. Background Art

[0002] Power semiconductor devices are widely used in power converters. They offer excellent power control performance and play an irreplaceable role in power systems, photovoltaic power generation systems, new energy vehicles, aerospace, and extreme environments. Currently, most power semiconductor devices utilize silicon-based diodes, power MOSFET transistors, and IGBTs (insulated-gate bipolar transistors). As power semiconductor devices based on silicon (Si) materials gradually reach their theoretical limits, the replacement rate of existing power semiconductor devices is slowing. Current research on Si-based devices makes it difficult to achieve further high-frequency, high-power density, and miniaturization of converters. Wide-bandgap semiconductor materials, such as silicon carbide (SiC) and gallium nitride (GaN), are rapidly developing. Their excellent material properties make them poised to replace Si materials in the future and drive innovation in the semiconductor industry, holding broad application prospects. However, in practical applications, SiC, GaN, and Ga2O3 all have certain limitations. For example: the electron mobility of SiC materials is relatively low, the degree of integration of GaN materials is not enough, its lattice constant and thermal expansion coefficient are difficult to match with other materials, and the thermal conductivity of Ga2O3 materials is relatively low, which makes heat dissipation of devices made from them a big problem.

[0003] The continuous progress of flexible electronic technology has helped to improve the portability, flexibility and biocompatibility of electronic products, and it will continue to be a major research hotspot in the future. The main advantage of flexible electronic devices is that the device itself has a three-dimensional curved surface structure or the device can be attached to a curved surface. In the medical field, especially in the testing of human physiological signals, due to the curved surface structure of the human skin or organ surface, traditional electronic measurement technology based on a "flat" substrate often cannot achieve the desired effect, and traditional measuring instruments often have disadvantages such as large size and complex testing methods. Flexible electronic devices have the advantages of being safe, lightweight, highly adaptable and easy to operate, which makes them have excellent performance in the field of testing human physiological signals. Most of the current power semiconductor devices are concentrated on the research of hard substrates such as Si, which makes the application scenarios of power devices very limited. In order to expand the application scope of power devices, the present invention creatively introduces a flexible substrate as the substrate of the device, which will greatly expand the application scenarios of power electronic devices.

[0004] Diamond is a new generation of ultra-wide bandgap semiconductor materials, boasting a range of advantages, including a wide bandgap, high thermal conductivity, high carrier mobility, high carrier saturation velocity, and excellent chemical stability. It is also known in the industry as the ultimate semiconductor material. Ultra-wide bandgap semiconductor materials, represented by diamond, feature high critical breakdown electric field, high saturation electron velocity, high electron density, high electron mobility, and high thermal conductivity. They are highly radiation-resistant semiconductor materials suitable for high-frequency, high-voltage, high-temperature, and high-power applications.

[0005] However, ideal diamond is an insulator, making it difficult to manufacture power devices. Reasonable doping is required to achieve diamond's semiconductor properties. While p-type doping of diamond is relatively easy to achieve, n-type doping is extremely challenging. Therefore, the issue of n-type conductivity is a major factor restricting the development of diamond-based power devices. The two-dimensional electron gas induced by polarized interfaces can achieve n-type conductivity in diamond, with high electron mobility. Given this, the present invention utilizes a diamond MOS-HEMT device based on the two-dimensional electron gas effect, enabling high-performance diamond n-type conductivity. Summary of the Invention

[0006] One of the objectives of the present invention is to provide a MOS-HEMT device based on the two-dimensional electron gas effect at the diamond / aluminum nitride polarization interface. A heterostructure is constructed between the AlN layer and the diamond layer to form a high-mobility two-dimensional electron gas (2DEG). The AlN film and the diamond form a polarization interface, realizing n-type conductivity of the diamond.

[0007] A second object of the present invention is to provide a method for preparing a MOS-HEMT device based on the two-dimensional electron gas effect at the diamond / aluminum nitride polarization interface, which is simple and easy to control.

[0008] The solution adopted by the present invention to achieve one of the objectives is: a MOS-HEMT device based on the two-dimensional electron gas effect of the diamond / aluminum nitride polarization interface, comprising:

[0009] A diamond substrate formed on a flexible substrate;

[0010] an AlN layer deposited on the surface of the diamond substrate;

[0011] a gate oxide dielectric layer deposited on a surface of the AlN layer;

[0012] a gate metal layer formed on a surface of the gate oxide dielectric layer;

[0013] The source electrode layer and the drain electrode layer are respectively deposited on the surface of the diamond substrate and located at both ends of the gate oxide dielectric layer and the AlN layer.

[0014] Preferably, the thickness of the flexible substrate is 1 μm-1 mm, the thickness of the diamond substrate is 10 nm-3 μm, the thickness of the AlN layer is 0.2-10 μm, the thickness of the gate oxide dielectric layer is 10-30 nm, the thickness of the source electrode and drain electrode layers are both 0.1-1 μm, and the thickness of the gate metal layer is 0.1-1 μm.

[0015] Preferably, the gate oxide dielectric layer is at least one of aluminum oxide, silicon dioxide, and silicon nitride.

[0016] Preferably, the source electrode layer, the drain electrode layer and the gate metal layer are at least one of an aluminum layer and a gold layer.

[0017] Preferably, the flexible substrate is flexible glass or indium tin oxide.

[0018] The solution adopted by the present invention to achieve the second purpose is: a method for preparing a diamond MOS-HEMT device based on the polarization interface two-dimensional electron gas effect, comprising the following steps:

[0019] Preparing a diamond thin film substrate on a flexible substrate surface;

[0020] An AlN layer is deposited on the surface of a diamond substrate using the MBE process (molecular beam epitaxy). A portion of the AlN layer is then etched away using photolithography and etching to create holes in the source and drain regions.

[0021] Depositing a source electrode and a drain electrode in the opening regions of the source electrode and the drain electrode respectively;

[0022] A gate oxide dielectric layer is prepared by depositing and growing a gate oxide dielectric film on the surface of the AlN layer;

[0023] A gate metal layer is deposited on the surface of the gate oxide dielectric layer.

[0024] The above-mentioned deposition processes all require annealing treatment.

[0025] Preferably, the process parameters for depositing the AlN layer on the surface of the diamond substrate using the MBE process are: background vacuum degree: 10 -9 -10 -10 Torr, working vacuum degree: the stable working pressure after nitrogen / nitride gas is introduced is 10 -5 -10 -6 Torr; growth temperature: 750-950℃, growth time includes initial low-temperature buffer layer: 200-400℃ to grow a 5-10nm thick low-temperature AlN buffer layer, main AlN layer growth: 750-950℃ to grow the target thickness, growth rate is 0.5-2μm / h, growth mode: layered / island mixed mode; growth rate: 0.1-0.5nm / s, annealing treatment: 800-1000℃ annealing in a nitrogen atmosphere.

[0026] Preferably, the nitrogen gas used in the MBE process for depositing the AlN layer on the surface of the diamond substrate is 99.9999% high-purity nitrogen gas, with a nitrogen plasma activation power of 300-450 W and a nitrogen flow rate of 0.5-1.5 sccm.

[0027] Preferably, the aluminum source used in the MBE process to deposit the AlN layer on the surface of the diamond substrate is: 99.9999% high purity aluminum, aluminum evaporation temperature: 850-950°C, aluminum beam flow rate: 1*10 -7 -5*10 -7 Torr.

[0028] Preferably, the deposition method is at least one of chemical vapor deposition, microwave plasma chemical vapor deposition, thermal ion deposition, evaporation, sputtering, atomic layer deposition, and physical vapor deposition.

[0029] The present invention has the following advantages and beneficial effects:

[0030] The MOS-HEMT device of the present invention constructs a heterostructure between the AlN thin film layer and the diamond to form a high-mobility two-dimensional electron gas (2DEG). The AlN thin film layer and the diamond form a polarized surface to achieve n-type conductivity of the diamond.

[0031] The MOS-HEMT device of this invention boasts high electron mobility, effectively improving electrical conductivity and minimizing device losses. Diamond's high thermal conductivity facilitates low thermal resistance, making it suitable for high-temperature environments. The diamond / AlN power HEMT device achieves diamond's n-type conductivity, broadening the development prospects of diamond-based power devices and laying a solid foundation for the next generation of high-performance power devices.

[0032] The preparation method of the present invention utilizes the MBE process to deposit an AlN layer on the surface of a diamond layer. By precisely controlling the atomic beam, a high-crystalline-quality AlN film with a low dislocation density and good crystal orientation can be obtained on a diamond substrate. MBE can control the growth thickness with atomic-level precision, making it ideal for preparing ultrathin films or heterostructures. Furthermore, compared to chemical vapor deposition (CVD), MBE has a lower growth temperature (typically 750-950°C), which is particularly beneficial for temperature-sensitive diamond substrates and can reduce surface damage and carbonization issues. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the MOS-HEMT device of the present invention;

[0034] Figure 2 is the X-ray diffraction pattern of the polarization interface of the present invention;

[0035] Figure 3 Schematic diagram of the diamond film provided for the MOS-HEMT device of the present invention;

[0036] Figure 4 Schematic diagram of forming an AlN layer, a source electrode layer, and a drain electrode layer for a MOS-HEMT device of the present invention;

[0037] Figure 5 A schematic diagram of forming a gate oxide dielectric layer for a MOS-HEMT device according to the present invention;

[0038] Figure 6 A schematic diagram of forming a gate metal layer for a MOS-HEMT device according to the present invention;

[0039] In the figure, 1 is a flexible substrate, 2 is a diamond substrate, 3 is an AlN layer, 4 is a gate oxide dielectric layer, S is a source electrode layer, D is a drain electrode layer, and G is a gate metal layer. DETAILED DESCRIPTION

[0040] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0041] Example 1

[0042] like Figure 1 As shown, this embodiment provides a MOS-HEMT device, including:

[0043] A diamond substrate 2 prepared on a flexible substrate 1;

[0044] an AlN layer 3 deposited on the surface of the diamond substrate 2;

[0045] a gate oxide dielectric layer 4 deposited on the surface of the AlN layer 3;

[0046] A gate metal layer G formed on the surface of the gate oxide dielectric layer 4;

[0047] The source electrode layer S and the drain electrode layer D are respectively deposited on the surface of the diamond substrate 2 and located at both ends of the gate oxide dielectric layer G and the AlN layer 3 .

[0048] The thickness of the flexible substrate 1 is 1 μm-1 mm, the thickness of the diamond substrate 2 is in the range of 0.2 μm-10 μm, the thickness of the AlN layer 3 is 10 nm-3 μm, the thickness of the gate oxide dielectric layer 4 is 10 nm-30 nm, the thickness of the source electrode layer S and the drain electrode layer D are both 0.1 μm-1 μm, and the thickness of the gate metal layer G is 0.1 μm-1 μm.

[0049] The gate oxide dielectric layer is at least one of aluminum oxide, silicon dioxide, and silicon nitride, and is preferably a silicon dioxide layer in this embodiment.

[0050] The source electrode layer, drain electrode layer and gate metal layer are at least one of an aluminum layer and a gold layer. In this embodiment, the aluminum layer is preferred.

[0051] The flexible substrate is flexible glass or indium tin oxide, and indium tin oxide is preferred in this embodiment.

[0052] like Figure 2 As shown in the figure, the X-ray diffraction performance characteristics of the MOS-HEMT device in this embodiment are as follows. A two-dimensional electron gas (2DEG) is formed between the diamond layer and the AlN substrate, which increases the electron mobility of the device to more than 1000 cm 2 / V·s, realizing n-type conductivity of diamond semiconductor devices and improving device performance.

[0053] Example 2

[0054] A method for preparing a MOS-HEMT device based on the two-dimensional electron gas effect at a diamond / aluminum nitride polarization interface comprises the following steps:

[0055] The method for preparing a diamond film includes: dispersing diamond powder into an ethanol solution, and obtaining a diamond solution with uniform particle size by magnetic stirring or other methods; growing a diamond film on a flexible substrate by a multiple coating and drying process, wherein the coating methods include but are not limited to spin coating, spray coating, and drop coating, and the spin coating method is preferred in this embodiment;

[0056] Using the MBE process to grow an AlN film on the diamond film;

[0057] A portion of the AlN layer is etched away using photolithography and etching methods to open holes in the source and drain regions;

[0058] The source and drain electrodes are prepared by physical vapor deposition, wherein the deposition process includes but is not limited to evaporation, sputtering, etc., and sputtering is preferred in this embodiment;

[0059] A gate oxide dielectric film is grown on the AlN layer using a deposition method, wherein the deposition method includes but is not limited to atomic layer deposition, chemical vapor deposition, etc., and chemical vapor deposition is preferred in this embodiment;

[0060] The gate metal layer is manufactured using photolithography and physical vapor deposition methods. The deposition process includes but is not limited to evaporation, sputtering, etc., and sputtering is preferred in this embodiment.

[0061] The deposition processes mentioned above all require annealing treatment, which is a conventional method and will not be described in detail here.

[0062] Figure 3 Schematic diagram of the diamond film provided for the MOS-HEMT device of the present invention.

[0063] Figure 4 Schematic diagram of forming an AlN layer, a source electrode layer, and a drain electrode layer for the MOS-HEMT device of the present invention.

[0064] Figure 5 Schematic diagram of forming a gate oxide dielectric layer for a MOS-HEMT device according to the present invention.

[0065] Figure 6 Schematic diagram of forming a gate metal layer for a MOS-HEMT device according to the present invention.

[0066] In this embodiment, the specific steps and parameters for growing an AlN film on a diamond film using the MBE process are as follows:

[0067] 1. Cleaning the surface of diamond film:

[0068] Use high-purity acetone and ethanol to ultrasonically clean for 5-10 minutes each to remove surface organic pollutants.

[0069] Soak in hydrofluoric acid (HF) solution to remove the oxide layer (the specific time is adjusted according to the oxidation degree of the substrate).

[0070] After drying, the film is placed in an MBE system for high-temperature annealing (under vacuum or hydrogen environment) to further clean the surface.

[0071] 2. Cavity and vacuum environment

[0072] Background vacuum: 10 -9 -10 -10 Torr.

[0073] Working vacuum degree: The stable working pressure after nitrogen / nitride gas is introduced is 10 -5 -10 -6 Torr.

[0074] 3. Nitrogen source parameters

[0075] Nitrogen type: High-purity nitrogen (99.9999%), activated by a plasma source to generate active nitrogen (N atoms or N2 molecules).

[0076] Nitrogen plasma activation power: 300-450W (adjusted according to equipment specifications).

[0077] Nitrogen flow rate: 0.5-1.5 sccm (standard cubic centimeters per minute).

[0078] 4. Aluminum source parameters

[0079] Aluminum source form: High-purity aluminum (99.9999%) is used, supplied by a thermal evaporation source or a Knudsen source.

[0080] Aluminum evaporation temperature: 850-950℃ (the actual evaporation temperature depends on the equipment calibration).

[0081] Aluminum beam flow rate: 1*10 -7 -5*10 -7 Torr (measured in partial pressure).

[0082] 5. Substrate temperature

[0083] Growth temperature: 750-950°C (optimized according to the thermal stability of the diamond surface and film quality).

[0084] Higher temperature helps to improve the crystallization quality of thin films, but too high temperature may cause carbonization or evaporation of the substrate surface.

[0085] Pretreatment temperature: 950-1100℃, used to remove residual contamination on the surface.

[0086] 6. Growth time

[0087] Initial low-temperature buffer layer: A 5-10 nm thick low-temperature AlN buffer layer is grown at 200-400°C to reduce the lattice mismatch.

[0088] Main AlN layer growth: 750-950°C to target thickness, growth rate is typically 0.5-2 μm / h.

[0089] 7. Growth pattern

[0090] Growth mode: layered / island mixed mode (Stranski-Krastanov mode), depending on the crystal quality and surface energy of the diamond surface.

[0091] Growth rate: 0.1-0.5nm / s, controlled by adjusting the aluminum source beam and nitrogen flow.

[0092] 8. Key process control

[0093] Surface flatness monitoring: Reflection high-energy electron diffraction (RHEED) is used to monitor the growth dynamics and crystallization quality of thin films in real time.

[0094] Lattice mismatch control: Use low-temperature buffer layers or doping (such as silicon and oxygen) to reduce interface stress.

[0095] Annealing treatment: Annealing in a nitrogen atmosphere (800-1000℃) can improve crystal quality and reduce interface defects.

[0096] The above description is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and changes can be made without departing from the principles of the present invention. These improvements and changes are also considered to be within the scope of protection of the present invention.

Claims

1. A MOS-HEMT device based on the two-dimensional electron gas effect of diamond / aluminum nitride polarization interface, characterized in that: include: A diamond substrate formed on a flexible substrate; an AlN layer deposited on the surface of the diamond substrate; A gate oxide dielectric layer deposited on the surface of the AlN layer; A gate metal layer formed on the surface of the gate oxide dielectric layer; The source electrode layer and the drain electrode layer are respectively deposited on the surface of the diamond substrate and located at both ends of the gate oxide dielectric layer and the AlN layer.

2. The diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The thickness of the flexible substrate is 1 μm-1 mm, the thickness of the diamond substrate is 10 nm-3 μm, the thickness of the AlN layer is 0.2-10 μm, the thickness of the gate oxide dielectric layer is 10-30 nm, the thickness of the source electrode and the drain electrode layer are both 0.1-1 μm, and the thickness of the gate metal layer is 0.1-1 μm.

3. The diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The gate oxide dielectric layer is at least one of aluminum oxide, silicon dioxide and silicon nitride.

4. The diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The source electrode layer, the drain electrode layer and the gate metal layer are at least one of an aluminum layer and a gold layer.

5. The diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 1, characterized in that: The flexible substrate is flexible glass or indium tin oxide.

6. A method for preparing a diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to any one of claims 1 to 5, characterized in that: The following steps are involved: Preparing a diamond thin film substrate on a flexible substrate surface; An AlN layer is deposited on the surface of a diamond substrate using an MBE process, and a portion of the AlN layer is etched away to open holes in the source and drain regions; Depositing a source electrode and a drain electrode in the opening regions of the source electrode and the drain electrode respectively; A gate oxide dielectric film is deposited and grown on the surface of the AlN layer to prepare a gate oxide dielectric layer; A gate metal layer is deposited on the surface of the gate oxide dielectric layer.

7. The method for preparing a diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 6, characterized in that: The process parameters for depositing the AlN layer on the surface of the diamond substrate using the MBE process are: background vacuum degree: 10 -9 -10 -10 Torr, working vacuum degree: the stable working pressure after nitrogen / nitriding gas is introduced is 10 -5 -10 -6 Torr; growth temperature: 750-950°C, growth time includes initial low-temperature buffer layer: 200-400°C to grow a 5-10nm thick low-temperature AlN buffer layer, main AlN layer growth: 750-950°C to grow target thickness, growth rate of 0.5-2μm / h, growth mode: layered / island mixed mode; growth rate: 0.1-0.5nm / s, annealing treatment: 800-1000°C annealing in a nitrogen atmosphere.

8. The method for preparing a diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 6, characterized in that: The nitrogen type used in the MBE process for depositing the AlN layer on the surface of the diamond substrate is 99.9999% high-purity nitrogen, the nitrogen plasma activation power is 300-450W, and the nitrogen flow rate is 0.5-1.5sccm.

9. The method for preparing a diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 6, characterized in that: The aluminum source used in the MBE process to deposit the AlN layer on the surface of the diamond substrate is: 99.9999% high-purity aluminum, aluminum evaporation temperature: 850-950°C, aluminum beam flux: 1*10 -7 -5*10 -7 Torr.

10. The method for preparing a diamond MOS-HEMT device based on polarization interface two-dimensional electron gas effect according to claim 6, characterized in that: The deposition method is at least one of chemical vapor deposition, microwave plasma chemical vapor deposition, thermal ion deposition, evaporation, sputtering, atomic layer deposition, and physical vapor deposition.

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