Method for realizing isolation of gallium nitride device by proton irradiation technology

Abstract

The invention belongs to the technical field of semiconductors, and provides a method for isolating a gallium nitride device by a proton irradiation technology, which comprises the following steps of: performing selective proton irradiation by using a lead mask plate, and performing proton irradiation treatment on the device by using a proton irradiation device; after irradiation is completed, metal films T , A < l >, N and Au are evaporated on one side of the GaN substrate, annealing is conducted in the nitrogen atmosphere, and a cathode is prepared; and evaporating metal films N and Au at one end of the n-GaN layer, and removing redundant metal films to form an anode. According to the method, a local deep energy level defect is introduced into the GaN material through a high-energy proton beam by using proton irradiation, so that the material forms high resistance in a specific region, and then electrical isolation is realized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for isolating gallium nitride devices using proton irradiation technology. Background Art

[0002] Gallium nitride (GaN), as the third generation wide bandgap semiconductor material, has demonstrated superior performance in high frequency, high power and high temperature environments due to its advantages such as wide bandgap, high breakdown electric field and high electron mobility. Compared with traditional silicon (Si) and gallium arsenide (GaAs) materials, the material properties of GaN make it popular in applications such as power electronics, radio frequency (RF) communications and microwave power amplifiers, especially in the fields of 5G communications and high power devices. However, the realization of GaN device performance not only depends on the properties of the material itself, but also is closely related to the quality of the substrate and its electrical properties. High-quality GaN substrates can improve the reliability and efficiency of devices, especially in RF and power devices, where the insulation performance of the substrate is crucial to the performance of the device. Therefore, how to effectively achieve electrical isolation of GaN devices has become one of the key factors in improving their performance.

[0003] In GaN-based device design, device isolation technology is a necessary means to ensure electrical insulation between devices. Different isolation methods can effectively suppress leakage current and reduce parasitic effects, thereby improving the stability, efficiency and overall performance of the device. Commonly used GaN device isolation methods include:

[0004] 1) Etching trench isolation: Physical isolation trenches are formed on the GaN substrate by chemical or plasma etching to achieve isolation between devices. This method is simple and direct, but it damages the surface morphology of the material and may cause defects, thus affecting the reliability of the device.

[0005] (2) Ion implantation isolation: A high resistance region is formed by implanting deep energy level impurity ions. Ion implantation can effectively increase the resistivity of the isolation region and inhibit lateral conduction. However, this method will introduce lattice defects and stress, resulting in a decrease in material performance, and high temperature annealing is usually required after ion implantation to repair the material structure.

[0006] (3) Oxide layer isolation: deposit an oxide film on the GaN substrate and isolate the device through a dielectric layer. This method is relatively mature, but there is a problem of high parasitic capacitance, especially in high-frequency devices, which may cause unnecessary capacitance effects and affect device performance. Summary of the invention

[0007] Based on these problems, the purpose of the present invention is to provide a method for isolating gallium nitride devices using proton irradiation technology, which uses proton irradiation to introduce local deep energy level defects in GaN materials through high-energy proton beams, so that the material forms high resistance in specific areas, thereby achieving electrical isolation.

[0008] To achieve the above object, the present invention provides the following technical solutions.

[0009] In a first aspect, the present invention provides a method for isolating a gallium nitride device using proton irradiation technology, comprising the following steps:

[0010] preparing a gallium nitride single crystal substrate, and growing an n-GaN layer on the gallium nitride single crystal substrate;

[0011] Selectively irradiating the device with protons using a lead mask and irradiating the device with protons using a proton irradiation device;

[0012] After the irradiation is completed, metal films Ti, Al, Ni and Au are evaporated on one side of the GaN substrate and annealed in a nitrogen atmosphere to prepare a cathode;

[0013] At one end of the n-GaN layer, metal films Ni and Au are evaporated, and the excess metal film is removed to form an anode.

[0014] As a further embodiment of the present invention, a single-crystal GaN substrate is prepared with a thickness of 300 μm and silicon (Si) is used as a dopant with a doping concentration of 5×10 18 cm -3 .

[0015] As a further embodiment of the present invention, when growing an n-GaN layer on a gallium nitride single crystal substrate, a 20 μm-50 μm thick n-GaN layer is grown by hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD) method, and silicon (Si) is used as a dopant with a doping concentration of 5×10 17 cm-3.

[0016] As a further solution of the present invention, an n-GaN layer with a thickness of 40 μm is grown on a gallium nitride single crystal substrate.

[0017] As a further embodiment of the present invention, when selective proton irradiation is performed using a lead mask, the irradiation energy is 5 MeV and the dose is 5×10 17 cm -2 , forming a high-resistance isolation region.

[0018] As a further solution of the present invention, the proton irradiation device is the China Advanced Research Reactor of the China Institute of Atomic Energy, namely the "Yanlong" pool reactor.

[0019] As a further solution of the present invention, a proton irradiation device is used to perform proton irradiation treatment on the device, comprising the following steps:

[0020] a) Target chamber setting: A mobile irradiation target stand is set in the target chamber. The target stand is driven by a bottom motor and moves along the Y-axis and Z-axis directions, and can rotate around the Z-axis at a certain angle;

[0021] b) Sample installation and positioning: A 50 cm x 50 cm rectangular porous resin plate is fixed on the target frame for mounting the device to be irradiated. The device to be irradiated is pre-positioned by the cross laser on the inner wall of the target chamber, and the positioning coordinates of the device are recorded;

[0022] c) Vacuum system and beam diagnosis: hoist the top cover to seal the target chamber, turn on the vacuum system, and perform beam diagnosis after the set air pressure is reached;

[0023] d) Accelerator preparation: using the accelerator to extract the ion beam;

[0024] e) Beam guidance and adjustment: The ion beam is drawn out from the ion source, accelerated and transmitted to the branch pipe, deflected by the quadrupole magnet, and collimated by the guide; the beam is evenly diffused on the scattering target, and then the beam spot size is adjusted by the slit light barrier;

[0025] f) Preparation for irradiation experiment: After ensuring that the beam diagnosis is correct, start the irradiation experiment.

[0026] As a further solution of the present invention, beam diagnosis is performed by a detector array fixed on the target holder to measure the beam energy and flux intensity; during the irradiation process, the pressure in the vacuum target chamber is kept constant at 4x10 -3 Pa.

[0027] As a further embodiment of the present invention, an HI-13 tandem accelerator is used to introduce 1 H- 197 The ion beam current between Au.

[0028] As a further solution of the present invention, when the irradiation experiment starts, multiple devices are placed on the target frame, and the movement of the target frame is remotely controlled according to the recorded positioning coordinates to switch the devices.

[0029] As a further embodiment of the present invention, the irradiation energy during proton irradiation is 3MeV-10MeV, and the irradiation dose is 2×10 17 -8×10 17 cm -2 .

[0030] As a further embodiment of the present invention, the irradiation energy during proton irradiation is 5 MeV and the irradiation dose is 5×10 17 cm -2 .

[0031] As a further solution of the present invention, metal films Ti, Al, Ni and Au are evaporated on one side of the GaN substrate with thicknesses of 25 nm, 100 nm, 25 nm and 60 nm respectively, and annealed in a nitrogen atmosphere for 60 seconds at a temperature of 800°C.

[0032] As a further solution of the present invention, the thicknesses of Ni and Au metal films evaporated on one end of the n-GaN are 20 nm and 60 nm respectively.

[0033] Compared with the prior art, the method for isolating gallium nitride devices by proton irradiation technology provided by the present invention forms local deep energy level defects in GaN materials by introducing high-energy proton beams, thereby forming high resistance in specific areas, and has the following beneficial effects:

[0034] 1. Non-destructive isolation: The proton irradiation of the present invention does not cause significant damage to the crystal structure of the GaN material, which is in sharp contrast to physical or chemical methods such as etching or ion implantation. The proton irradiation of the present invention can achieve electrical isolation while maintaining the integrity of the material, avoiding destructive effects on the GaN crystal, thereby improving the overall performance and reliability of the device.

[0035] 2. Precise control of defect introduction: The present invention can precisely control the defect distribution and concentration generated in the GaN material by adjusting the energy and irradiation dose of the proton beam through proton irradiation. This control capability enables the resistivity of the isolation region to be precisely controlled to ensure the stability and reliability of the isolation effect. In contrast, the defects introduced by the ion implantation method are often uneven and easily cause lattice stress and structural damage.

[0036] 3. Wide applicability: The proton irradiation of the present invention is applicable to GaN substrates of different sizes and device structures of various shapes, and has high scalability. Whether it is a small device or a large-area GaN device, proton irradiation can be effectively applied, and is particularly suitable for the isolation needs of large-scale production and complex-structured GaN devices.

[0037] 4. Simplified process flow: The present invention does not require complicated post-processing steps such as high-temperature annealing or surface polishing through proton irradiation, which significantly simplifies the process flow and reduces manufacturing costs. Compared with traditional ion implantation and oxide layer isolation methods, proton irradiation does not require additional process steps, reduces process time and resource consumption, and improves production efficiency.

[0038] 5. Lower parasitic capacitance and leakage current: The present invention introduces deep energy level defects and proton irradiation to achieve high resistance isolation areas, thereby effectively reducing parasitic capacitance and leakage current. This is particularly important for high-frequency and high-power application scenarios, and can significantly improve the performance and stability of the device.

[0039] 6. Economical and efficient: The proton irradiation technology used in the present invention is low in cost and does not require expensive equipment and materials, thus reducing production costs. At the same time, proton irradiation technology simplifies the manufacturing process, reduces production steps and time, and makes the overall manufacturing process more economical and efficient.

[0040] In summary, the proton irradiation technology of the present invention has significant advantages in achieving GaN device isolation, innovatively solves the shortcomings of traditional isolation methods, and provides reliable technical support for the efficient production and high-performance application of GaN devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention.

[0042] Figure 1 A process flow chart of a method for isolating gallium nitride devices using proton irradiation technology provided by the present invention;

[0043] Figure 2 A schematic diagram of the principle of implementing gallium nitride semi-insulating substrate irradiation in a method for implementing gallium nitride device isolation using proton irradiation technology provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following description and the accompanying drawings fully illustrate the specific embodiments of this paper so that those skilled in the art can practice them. The parts and features of some embodiments may be included in or replace the parts and features of other embodiments. The scope of the embodiments herein includes the entire scope of the claims, and all available equivalents of the claims.

[0045] Herein, the terms "first", "second", etc. are used only to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "comprise", "comprising", or any other variants thereof are intended to cover non-exclusive inclusion, so that a structure, system, or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such structure, system, or device.

[0046] Due to optical limitations and equipment resolution constraints, the images obtained by traditional endoscopes in narrow body cavities may not be clear enough due to lighting and field of view limitations. The cameras equipped with most endoscopes do not meet HD or UHD standards, and their resolution limits doctors' ability to diagnose lesions, resulting in the inability to provide doctors with endoscopic images with sufficient details for diagnosis. Therefore, real-time processing of such endoscopic images is crucial, especially in high-resolution reconstruction, real-time correction, and feature recognition.

[0047] The existing methods for isolating gallium nitride (GaN) devices are to form physical isolation grooves on the GaN substrate by chemical or plasma etching during the isolation of etching grooves to achieve isolation between devices. This method is simple and direct, but it damages the surface morphology of the material and may cause defects, thereby affecting the reliability of the device. During ion implantation isolation, a high resistance region is formed by injecting deep energy level impurity ions. Ion implantation can effectively increase the resistivity of the isolation area and inhibit lateral conduction. However, this method introduces lattice defects and stress, resulting in a decrease in material performance, and high temperature annealing is usually required after ion implantation to repair the material structure. During oxide layer isolation, a layer of oxide film is deposited on the GaN substrate to isolate the device through a dielectric layer. This method is relatively mature, but there is a problem of high parasitic capacitance, especially in high-frequency devices, which may cause unnecessary capacitance effects and affect device performance.

[0048] Based on these problems, a method of isolating GaN devices using proton irradiation technology was proposed. The typical feature is to use proton irradiation to introduce local deep energy level defects in GaN materials through high-energy proton beams, so that the material forms high resistance in specific areas, thereby achieving electrical isolation.

[0049] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0050] See also Figure 1 As shown, an embodiment of the present invention provides a method for isolating a gallium nitride device using a proton irradiation technique, taking a Schottky diode as an example, and comprising the following steps:

[0051] Step S10: preparing a gallium nitride single crystal substrate.

[0052] The prepared GaN single crystal substrate has a thickness of 300 μm and uses silicon (Si) as a dopant with a doping concentration of 5×10 18 cm -3 .

[0053] Step S20 , growth of an n-GaN layer.

[0054] When growing an n-GaN layer on a gallium nitride single crystal substrate, a 40 μm thick n-GaN layer is grown by hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD) using silicon (Si) as a dopant with a doping concentration of 5×10 17 cm-3.

[0055] Step S30: Proton irradiation to achieve isolation.

[0056] Use lead mask for selective proton irradiation, and use proton irradiation device to treat the device with proton irradiation. Among them, modern micromachining technology is used to make high-precision lead mask for selective irradiation during proton irradiation, so as to achieve isolation. Use the China Advanced Research Reactor (CARR) of the China Institute of Atomic Energy, also known as the "Yanlong" pool reactor, to treat the device with proton irradiation. The specific irradiation process is as follows:

[0057] a) Target chamber setting: A mobile irradiation target stand is set in the target chamber. The target stand is driven by a bottom motor and moves along the Y-axis and Z-axis directions, and can rotate around the Z-axis at a certain angle;

[0058] b) Sample installation and positioning: A 50 cm x 50 cm rectangular porous resin plate is fixed on the target frame for mounting the device to be irradiated. The device to be irradiated is pre-positioned by the cross laser on the inner wall of the target chamber, and the positioning coordinates of the device are recorded;

[0059] c) Vacuum system and beam diagnosis: The top cover is hoisted to close the target chamber, and the vacuum system is turned on. After the set air pressure is reached, beam diagnosis is performed. Beam diagnosis is completed by the detector array fixed on the target holder to measure the beam energy and flux. During the irradiation process, the air pressure in the vacuum target chamber is kept constant at 4x10 -3 Pa.

[0060] d) Accelerator preparation: Use HI-13 tandem accelerator to extract 1 H- 197 The ion beam current between Au.

[0061] e) Beam guidance and adjustment: The ion beam is drawn out from the ion source, accelerated and transmitted to the branch pipe, deflected by the quadrupole magnet, and collimated by the guide; the beam is evenly diffused on the scattering target, and then the beam spot size is adjusted by the slit light barrier;

[0062] f) Preparation for irradiation experiment: After ensuring that the beam diagnosis is correct, start the irradiation experiment. When starting the irradiation experiment, multiple devices are placed on the target frame, and the target frame is remotely controlled to move according to the recorded positioning coordinates to switch the devices.

[0063] g) Proton irradiation parameters: The irradiation energy during proton irradiation is 5 MeV and the irradiation dose is 5×10 17 cm -2 , thus achieving device isolation effect.

[0064] Step S40: cathode preparation.

[0065] Metal films Ti, Al, Ni and Au with thicknesses of 25 nm, 100 nm, 25 nm and 60 nm are deposited on one side of the GaN substrate by magnetron sputtering or electron beam evaporation, and annealed in a nitrogen atmosphere for 60 seconds at a temperature of 800°C.

[0066] Step S50: preparing anode.

[0067] On the n-GaN side, combined with the photolithography process, magnetron sputtering, thermal evaporation or electron beam evaporation is used to evaporate the metal films Ni and Au with a thickness of 20nm and 60nm respectively, and then the excess metal film is removed by the stripping process to form an anode.

[0068] See also Figure 2 As shown, the diode cathode uses a stacked structure of Ti, Al, Ni and Au with thicknesses of 25nm, 100nm, 25nm and 60nm respectively. Figure 2 Middle component 1.

[0069] GaN single crystal substrate, thickness 300μm, using Si as dopant, doping concentration 5×10 18 cm -3 ,like Figure 2 Middle component 2.

[0070] The n-GaN layer has a thickness of 40 μm and uses Si as a dopant with a doping concentration of 5 × 10 17 cm -3 ,like Figure 2 Middle component 3.

[0071] The high-resistance isolation zone is formed by proton irradiation. The irradiation energy during proton irradiation is 5 MeV (the irradiation energy is 3-10 MeV, and 5 MeV is the best here), and the dose is 5×10 17 cm -2 (The irradiation dose is 2-8×10 17 cm -2， The best value here is 5×10 17 cm -2 ), so as to achieve device isolation effect, such as Figure 2 Middle component 4.

[0072] The diode anode uses a Ni and Au stacked structure with thicknesses of 20nm and 60nm respectively. Figure 2Middle component 6.

[0073] The present invention proposes a method for isolating gallium nitride devices using proton irradiation technology. The typical feature is to use proton irradiation to introduce local deep energy level defects in GaN materials through high-energy proton beams, so that the material forms high resistance in specific areas, thereby achieving device isolation. The advantages are as follows:

[0074] (1) Non-destructive isolation: Unlike physical or chemical methods such as etching or ion implantation, proton irradiation does not cause significant damage to the crystal structure of GaN materials, so isolation can be achieved while maintaining the integrity of the material.

[0075] (2) Precise control of defect introduction: Proton irradiation can precisely control the defect distribution and concentration in the GaN material by adjusting the energy and irradiation dose of the proton beam, thereby achieving precise control of the resistivity of the isolation region. Compared with ion implantation, the defects introduced by proton irradiation are more uniform, avoiding lattice stress and excessive structural damage. Secondly, the cost of proton irradiation is lower.

[0076] (3) Wide applicability: Proton irradiation technology can be used for GaN substrates of different sizes and device structures of various shapes. It is highly scalable and is particularly suitable for the isolation of large-area GaN devices.

[0077] (4) Simplified process flow: Proton irradiation does not require complex post-processing steps, such as high-temperature annealing or surface polishing, which significantly simplifies the process flow and reduces manufacturing costs. Compared with traditional ion implantation and oxide layer isolation, proton irradiation technology is more economical and efficient.

[0078] (5) Lower parasitic capacitance and leakage current: By introducing deep energy level defects, proton irradiation can achieve high resistance isolation areas while avoiding parasitic capacitance problems caused by oxide layers or physical isolation, which is particularly suitable for high-frequency and high-power application scenarios.

[0079] A method of isolating GaN devices using proton irradiation technology. The typical feature is that proton irradiation is used to introduce local deep energy level defects in GaN materials through high-energy proton beams, so that the material forms high resistance in specific areas, thereby achieving device isolation. Compared with traditional device isolation methods, this method has the following advantages: non-destructive isolation, precise control of defect introduction, wide applicability, simpler process flow, lower parasitic capacitance and leakage current, etc. Any method based on similar proton irradiation to achieve device isolation is protected.

[0080] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for isolating gallium nitride devices using proton irradiation technology, characterized in that: The following steps are involved: preparing a gallium nitride single crystal substrate, and growing an n-GaN layer on the gallium nitride single crystal substrate; Selectively irradiating the device with protons using a lead mask and irradiating the device with protons using a proton irradiation device; After the irradiation is completed, metal films Ti, Al, Ni and Au are evaporated on one side of the GaN substrate and annealed in a nitrogen atmosphere to prepare a cathode; At one end of the n-GaN layer, metal films Ni and Au are evaporated, and the excess metal film is removed to form an anode.

2. The method for isolating gallium nitride devices using proton irradiation technology according to claim 1, characterized in that: The prepared GaN single crystal substrate has a thickness of 300 μm and uses silicon as a dopant with a doping concentration of 5×10 18 cm -3 .

3. The method for isolating gallium nitride devices using proton irradiation technology according to claim 2, characterized in that: When growing an n-GaN layer on a gallium nitride single crystal substrate, a 20 μm-50 μm thick n-GaN layer is grown by hydride vapor phase epitaxy, molecular beam epitaxy or metal organic chemical vapor deposition, using silicon as a dopant with a doping concentration of 5×10 17 cm-3.

4. The method for isolating gallium nitride devices using proton irradiation technology according to claim 3, characterized in that: When selective proton irradiation was performed using a lead mask, the irradiation energy was 5 MeV and the dose was 5×10 17 cm -2 , forming a high-resistance isolation region.

5. The method for isolating gallium nitride devices using proton irradiation technology according to claim 4, wherein the device is subjected to proton irradiation treatment using a proton irradiation device, comprising the following steps: a) Target chamber setting: A mobile irradiation target stand is set in the target chamber. The target stand is driven by a bottom motor and moves along the Y-axis and Z-axis directions, and can rotate around the Z-axis at a certain angle; b) Sample installation and positioning: A 50 cm x 50 cm rectangular porous resin plate is fixed on the target frame for mounting the device to be irradiated. The device to be irradiated is pre-positioned by the cross laser on the inner wall of the target chamber, and the positioning coordinates of the device are recorded; c) Vacuum system and beam diagnosis: hoist the top cover to seal the target chamber, turn on the vacuum system, and perform beam diagnosis after the set air pressure is reached; d) Accelerator preparation: using the accelerator to extract the ion beam; e) Beam guidance and adjustment: The ion beam is drawn out from the ion source, accelerated and transmitted to the branch pipe, deflected by the quadrupole magnet, and collimated by the guide; the beam is evenly diffused on the scattering target, and then the beam spot size is adjusted by the slit light barrier; f) Preparation for irradiation experiment: After ensuring that the beam diagnosis is correct, start the irradiation experiment.

6. The method for isolating gallium nitride devices using proton irradiation technology according to claim 5, characterized in that: Beam diagnostics are performed using a detector array fixed to the target holder to measure beam energy and intensity. During irradiation, the pressure in the vacuum target chamber is kept constant at 4x10 -3 Pa.

7. The method for isolating gallium nitride devices using proton irradiation technology according to claim 5, characterized in that: Use HI-13 tandem accelerator to extract 1 H- 197 The ion beam current between Au.

8. The method for isolating gallium nitride devices using proton irradiation technology according to claim 5, characterized in that: When the irradiation experiment begins, multiple devices are placed on the target stand, and the movement of the target stand is remotely controlled according to the recorded positioning coordinates to switch the devices.

9. The method for isolating gallium nitride devices using proton irradiation technology according to claim 5, characterized in that: The irradiation energy of proton irradiation is 5 MeV and the irradiation dose is 5×10 17 cm -2 .

10. The method for isolating gallium nitride devices using proton irradiation technology according to claim 1, characterized in that: Metal films Ti, Al, Ni and Au were evaporated on one side of the GaN substrate with thicknesses of 25nm, 100nm, 25nm and 60nm respectively, and annealed in a nitrogen atmosphere for 60 seconds at a temperature of 800°C; metal films Ni and Au were evaporated on one end of the n-GaN substrate with thicknesses of 20nm and 60nm respectively.

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