Gallium nitride device structure and preparation method thereof

Abstract

The invention provides a gallium nitride device structure and a preparation method thereof.The method comprises the steps that firstly, a gallium nitride device is provided, the gallium nitride device comprises a substrate and an epitaxial structure which are stacked in sequence, then irradiation treatment with preset dose and preset energy is conducted on the gallium nitride device, defects are introduced into the epitaxial structure through irradiation treatment, and the gallium nitride device is obtained; modulation processing on the internal trap effect of the epitaxial structure is achieved, then modulation on the electrical performance of the gallium nitride device is achieved, and the reliability and stability of the gallium nitride device applied to the high-voltage and high-frequency field are improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor production process technology, and in particular to a gallium nitride device structure and a preparation method thereof. Background Art

[0002] Gallium nitride (GaN), as a wide bandgap semiconductor material, has shown great application potential in high-frequency, high-power power electronic devices due to its excellent electron mobility, high breakdown voltage and good thermal conductivity. As a result, GaN-based high electron mobility transistors (HEMTs) have become the core components of power electronic systems.

[0003] At present, the mainstream technology of GaN devices is planar devices that perform heteroepitaxial growth on substrates such as silicon, silicon carbide and sapphire. The difference in carrier conduction between GaN devices and traditional Si-based metal oxide semiconductor field effect transistor (MOSFET) devices is that GaN devices mainly rely on the two-dimensional electron gas (2DEG) formed at the AlGaN / GaN heterojunction interface to make the device work, thereby achieving the conduction and transmission of current in the device. Moreover, the formation of the two-dimensional electron gas does not rely on any material doping, and a high-concentration two-dimensional electron gas can be formed only through the spontaneous polarization and piezoelectric polarization of the material at the AlGaN / GaN heterojunction interface.

[0004] Planar GaN devices based on heterogeneous substrates have problems such as high defect density of epitaxial materials and channel performance being easily affected by trap effects, which leads to dynamic on-resistance degradation. These problems fundamentally limit their application in high-voltage and high-power power electronic systems. The existing technology uses vertical GaN devices realized by homogeneous epitaxy on single-crystal GaN substrates. Although this can solve the problem of dynamic on-resistance degradation of planar GaN devices and enable the devices to have excellent electron mobility and high breakdown voltage characteristics, due to the electric field crowding effect at the edge of vertical GaN devices, the breakdown voltage of traditional vertical GaN devices is often lower than its theoretical limit, thereby limiting the development of vertical GaN devices to higher voltage levels.

[0005] Therefore, how to provide a GaN device structure and a preparation method thereof, which can address the deficiencies of existing GaN devices and improve the reliability and stability of GaN devices in high-voltage and high-power power electronic systems, has become one of the technical problems that people in this field urgently need to solve. Summary of the invention

[0006] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0007] To this end, the first objective of the present application is to propose a gallium nitride device structure and a preparation method thereof, which can improve the reliability and stability of gallium nitride devices in high-voltage and high-power power electronic systems.

[0008] To achieve the above-mentioned purpose, the first aspect of the present application proposes a method for preparing a gallium nitride device structure, including providing a gallium nitride device, wherein the gallium nitride device includes a substrate and an epitaxial structure stacked in sequence; placing the gallium nitride device on an irradiation platform, and using an irradiation processing system to irradiate the gallium nitride device with a preset dose and preset energy, so as to introduce defects in the epitaxial structure and modulate the trap effect of the epitaxial structure.

[0009] Optionally, the radiation treatment system performs radiation treatment of a preset dose and a preset energy on the gallium nitride device, including a combination of one or more of proton radiation treatment, electron radiation treatment and ultraviolet radiation.

[0010] Optionally, the irradiation treatment system further includes a first irradiation control component, which includes a silicon diode detector, a Faraday cup and a quadrupole lens. The proton irradiation treatment and / or the electron irradiation treatment uses a silicon diode detector to monitor the energy of the irradiation beam, uses a Faraday cup to monitor the dose of the irradiation beam, and uses a quadrupole lens to defocus the radiation beam and achieve uniform radiation.

[0011] Optionally, the irradiation treatment system further includes a second irradiation control component, the second irradiation control component includes an ultraviolet detector and a beam homogenizer, the ultraviolet irradiation treatment uses an ultraviolet detector to monitor the intensity of the irradiated ultraviolet light, and uses a beam homogenizer to defocus the irradiated ultraviolet light and achieve uniform radiation; wherein the ambient gas for the gallium nitride device to perform the ultraviolet irradiation treatment is O 3 .

[0012] Optionally, when the gallium nitride device is a planar gallium nitride device, the epitaxial structure includes a buffer layer and a channel layer composed of carbon intentionally doped gallium nitride and unintentionally doped gallium nitride stacked in sequence; the step of modulating the trap effect of the epitaxial structure is to make the capture rate of carriers by internal traps of the buffer layer smaller than the release rate.

[0013] Optionally, the step of performing irradiation treatment with a preset dose and preset energy on the gallium nitride device using the irradiation treatment system comprises:

[0014] Performing the proton irradiation treatment on the epitaxial structure by the irradiation treatment system, and introducing defects in the channel layer by utilizing the displacement effect of the proton irradiation;

[0015] Perform the electron irradiation treatment on the epitaxial structure by the irradiation treatment system, and introduce a large amount of space charges in the buffer layer by utilizing the ionization effect of the electron irradiation; or

[0016] The epitaxial structure is subjected to the ultraviolet radiation treatment by the radiation treatment system, and the surface defects of the epitaxial structure are repaired by the ultraviolet radiation, and energy is provided for releasing the internal trapped carriers of the buffer layer.

[0017] Optionally, it is characterized in that the step of using the radiation treatment system to perform radiation treatment on the gallium nitride device with a preset dose and preset energy includes:

[0018] Performing the proton irradiation treatment of a first energy threshold and a first dose threshold on the epitaxial structure by the irradiation treatment system, and introducing defects in the channel layer by utilizing the displacement effect of the proton irradiation;

[0019] The proton irradiation treatment of a second energy threshold and a second dose threshold is performed on the epitaxial structure by the irradiation treatment system, and a large amount of space charges are introduced into the buffer layer by utilizing the ionization effect of the proton irradiation.

[0020] Optionally, when the gallium nitride device is a vertical gallium nitride device, the epitaxial structure includes a drift layer composed of unintentionally doped gallium nitride on the substrate, and the step of modulating the trap effect of the drift layer by irradiation treatment is to increase the resistance of a preset position at the edge of the drift layer.

[0021] Optionally, the step of performing irradiation treatment with a preset dose and preset energy on the gallium nitride device using the irradiation treatment system comprises:

[0022] The electron irradiation treatment is performed on the preset edge position of the epitaxial structure by the irradiation treatment system, and a displacement effect of the electron irradiation is utilized to introduce defects into the preset edge position of the drift layer, so that the preset resistance of the edge of the drift layer is increased.

[0023] To achieve the above-mentioned purpose, a second aspect of the present application provides a gallium nitride device structure, which is prepared by any of the above-mentioned methods for preparing a gallium nitride device structure.

[0024] The gallium nitride device structure and the preparation method thereof provided by the present application have at least the following beneficial effects:

[0025] The present application provides a gallium nitride device structure and a preparation method thereof. The method first provides a gallium nitride device, which includes a substrate and an epitaxial structure stacked in sequence. The gallium nitride device is then irradiated with a preset dose and a preset energy. Defects are introduced into the epitaxial structure through the irradiation treatment to achieve modulation of the internal trap effect of the epitaxial structure, thereby achieving modulation of the electrical properties of the gallium nitride device, thereby improving the reliability and stability of the gallium nitride device in the application of high voltage and high frequency fields.

[0026] When the gallium nitride device is a planar GaN device, the irradiation treatment will make the internal traps of the epitaxial structure capture carriers at a rate lower than the release rate, thereby improving the dynamic resistance decay of the planar GaN device, thereby improving the operational stability and reliability of the planar GaN device. At the same time, the irradiation process will not damage other electrical properties of the planar GaN device, expanding the application of irradiated planar GaN devices in high voltage and high frequency fields.

[0027] When the gallium nitride device is a vertical GaN device, the irradiation treatment will introduce defects inside the epitaxial structure and increase the resistivity of the epitaxial structure at the preset irradiation position, promote the lateral distribution of the device's electric field, reduce the electric field concentration, and make the electric field uniform, thereby increasing the breakdown voltage of the vertical GaN device and expanding the application of the irradiated vertical GaN device in the high voltage and high frequency fields.

[0028] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0030] Figure 1 The present invention is a schematic diagram of a method for preparing a gallium nitride device structure according to an embodiment of the present application.

[0031] Figure 2 It is a schematic diagram of the irradiation process of a planar gallium nitride device structure according to an embodiment of the present application.

[0032] Figure 3 It is a schematic diagram of the process flow of a method for preparing a planar gallium nitride device structure according to an embodiment of the present application.

[0033] Figure 4 Schematic diagram of the irradiation process of a vertical gallium nitride device structure according to an embodiment of the present application.

[0034] 100 substrate; 200 epitaxial structure; 210 nucleation layer; 220 buffer layer; 230 channel layer; 240 barrier layer; 300 epitaxial structure; 310 first gallium nitride layer; 320 second gallium nitride layer; 330 third gallium nitride layer; 331 edge terminal; 332 P-type heavily doped region; 410 anode contacting electrode; 420 cathode contacting electrode. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0036] At present, the mainstream technology of GaN devices is planar devices that perform heteroepitaxial growth on substrates such as silicon, silicon carbide and sapphire. It mainly relies on the two-dimensional electron gas (2DEG) formed at the AlGaN / GaN heterojunction interface in the epitaxial structure as a current channel to achieve current conduction and transmission in the device. The formation of the two-dimensional electron gas does not rely on any material doping, but is only formed through the spontaneous polarization and piezoelectric polarization of the material at the AlGaN / GaN heterojunction interface, which enables GaN devices to show great application potential in high-frequency, high-power power electronic systems.

[0037] However, planar GaN devices based on heterogeneous substrates have a high defect density in epitaxial materials, and the channel performance is easily affected by the trap effect, which in turn causes changes in the 2DEG concentration and increases the dynamic on-resistance of the device, affecting the stability and reliability of planar GaN devices. This fundamentally limits the application of planar GaN devices in high-voltage and high-power power electronic systems.

[0038] The existing technology realizes vertical GaN devices through homogeneous epitaxy on single-crystal GaN substrates, so that the current conduction and transmission channels in the device are located inside the epitaxial structure, and are not easily affected by defect effects and show increased dynamic on-resistance. However, the electric field crowding effect at the edge of the vertical GaN device makes the breakdown voltage of traditional vertical GaN devices often lower than its theoretical limit, thereby limiting the development of vertical GaN devices to higher voltage levels.

[0039] Based on the above problems, the embodiments of the present application provide a GaN device structure and a method for preparing the same. By performing multiple irradiation treatments on the GaN device, the irradiation parameters and the irradiation process are precisely controlled, and the irradiated particles are used to modulate the interaction between the internal traps and carriers of the GaN epitaxial structure, thereby suppressing the dynamic resistance decay of the planar GaN device and improving the breakdown voltage of the vertical GaN device.

[0040] According to one aspect of the present application, a method for preparing a GaN device structure is provided, such as Figure 1 As shown, the method comprises the steps of:

[0041] S1, providing a GaN device, wherein the GaN device includes a substrate and an epitaxial structure stacked in sequence;

[0042] S2, placing the GaN device on an irradiation platform, and using an irradiation processing system to perform irradiation processing on the epitaxial structure of the GaN device with a preset dose and preset energy, and modulating the trap effect of the epitaxial structure by introducing defects in the epitaxial structure, thereby achieving the purpose of improving the electrical performance of the GaN device.

[0043] In some embodiments, Figure 2 As shown, when the GaN device is a planar GaN device, the irradiation treatment system is controlled to perform irradiation treatment on the planar GaN device with a preset irradiation dose and a preset irradiation energy, so that the capture rate of carriers by the internal traps of the epitaxial structure 200 is less than the release rate.

[0044] The irradiation treatment will produce displacement effect and ionization effect at different positions of the epitaxial structure 200 of the planar GaN device. The ionization effect can change the state of the internal traps of the epitaxial structure 200 and reduce the trap capture rate of carriers. The displacement effect can introduce new defects into the epitaxial structure 200 and promote the release process of the internal traps of the epitaxial structure 200 to the captured carriers through the tiny leakage current channels generated by the newly introduced defects.

[0045] Thus, the irradiation treatment system modulates the trap effect of the epitaxial structure 200 of the planar GaN device by irradiating the planar GaN device, so that the capture rate of carriers by the internal traps of the epitaxial structure 200 is less than the release rate, thereby improving the dynamic resistance decay of the planar GaN device, thereby improving the operation stability and reliability of the planar GaN device. At the same time, the irradiation process will not damage other electrical properties of the planar GaN device, expanding the application of the irradiated planar GaN device in the high voltage and high frequency fields.

[0046] As an example, the substrate 100 may be composed of silicon (Si), silicon carbide (SiC), sapphire (Al2O3) or any other suitable substrate material for epitaxially growing a III-V material layer. For substrate materials other than bulk gallium nitride (GaN), it is difficult to directly epitaxially grow a high-quality GaN semiconductor crystal layer on the substrate 100 due to the poor lattice matching between GaN and the substrate material.

[0047] The epitaxial structure 200 may be composed of a nucleation layer 210, a buffer layer 220, a channel layer 230 and a barrier layer 240 stacked in sequence. The nucleation layer 210 is deposited on the surface of the substrate 100, and can provide a growth surface for the subsequent epitaxial growth of a high-quality gallium nitride layer, so as to ease the lattice adaptation between gallium nitride and non-gallium nitride substrate materials and reduce the defect rate in the gallium nitride epitaxy process. The nucleation layer 210 may be gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN) or any other suitable material for growing gallium nitride (GaN). The buffer layer 220 and the channel layer 230 are gallium nitride (GaN) material layers sequentially grown on the surface of the nucleation layer 210 using thin film deposition technology. The buffer layer 220 is composed of a carbon intentionally doped gallium nitride material, and the channel layer 230 is formed on the buffer layer 220 and is composed of an unintentionally doped gallium nitride material. Introducing carbon into the gallium nitride material layer can increase the resistivity of the gallium nitride material layer. The barrier layer 240 is an electron supply layer and can be formed by epitaxial growth on the channel layer 230 using a thin film deposition technique. The barrier layer 240 can be made of aluminum gallium nitride (Al x Ga 1-x N), indium aluminum nitride (In x Al 1-x N) or any other material suitable for forming a heterojunction with the channel layer 230.

[0048] The above-mentioned thin film deposition techniques include but are not limited to chemical vapor deposition (CVD), hydride vapor phase epitaxy (HVPE), atomic layer deposition (ALD), molecular beam epitaxy (MBE) or a combination thereof. Chemical vapor deposition includes metal organic chemical vapor deposition (MOCVD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD) and atomic layer chemical vapor deposition (ALCVD).

[0049] The contact electrode is formed on the barrier layer 240, and may include a source electrode, a drain electrode, and a gate electrode, and the gate electrode is formed between the source electrode and the drain electrode. The source electrode and the drain electrode are formed on the barrier layer 240, and may be composed of titanium (Ti) / silicon (Si) / nickel (Ni), titanium (Ti) / aluminum (Al) / nickel (Ni), or any other suitable material that forms an ohmic contact with the barrier layer 240. The gate electrode is also formed on the barrier layer 240, including any material that forms a non-ohmic contact (a contact that does not show a linear IV characteristic) with the barrier layer 240.

[0050] Although the introduction of carbon in gallium nitride (GaN) can increase the resistivity of the gallium nitride buffer layer 220, the growth conditions for the introduction of carbon in gallium nitride are in direct conflict with the necessary growth conditions for high-quality gallium nitride, so that the carbon-doped gallium nitride (c-GaN) formed by epitaxial growth has poor crystal quality and morphology, and it is difficult to grow a thick layer of carbon-doped gallium nitride, thereby limiting the electrical breakdown performance of GaN devices. In addition, the higher structural defect density in gallium nitride with a higher carbon doping concentration may also lead to poor device performance, such as a larger leakage current and increased energy consumption when the device is turned off.

[0051] Therefore, the buffer layer 220 of the planar GaN device is irradiated by the irradiation treatment system to modulate the trap effect of the epitaxial structure 200, so that the capture rate of carriers by the internal traps of the epitaxial structure 200 is less than the release rate, thereby improving the dynamic resistance decay of the planar GaN device, thereby improving the operation stability and reliability of the planar GaN device. The irradiation treatment may specifically include a combination of one or more of proton irradiation treatment, electron irradiation treatment and ultraviolet irradiation treatment.

[0052] As an example, the step of using irradiation treatment in step S2 to make the capture rate of carriers of the internal traps of the epitaxial structure 200 less than the release rate can be a combination of proton irradiation treatment and electron irradiation treatment. First, the epitaxial structure 200 is subjected to proton irradiation treatment by the irradiation treatment system, and defects are introduced into the channel layer 230 composed of unintentionally doped gallium nitride by using the displacement effect of proton irradiation, and the tiny leakage current channel generated by the newly introduced defects is used to promote the release process of the captured carriers by the internal traps of the buffer layer 220 composed of carbon intentionally doped gallium nitride. Then, the epitaxial structure 200 is subjected to electron irradiation treatment by the irradiation treatment system, and a large amount of space charge is introduced into the buffer layer 220 by using the ionization effect of electron irradiation. The space charge will affect the internal electric field distribution, and shield the capture of carriers by the internal traps of the buffer layer 220 through electric field modulation, directly interact with the internal traps of the buffer layer 220 to make the traps reach a saturated state, thereby reducing the capture rate of carriers by the internal traps of the buffer layer 220.

[0053] The irradiation treatment system may specifically include a first irradiation control component consisting of a silicon diode detector, a Faraday cup and a quadrupole lens. The proton irradiation treatment and / or electron irradiation treatment respectively use a silicon diode detector to monitor and control the energy of the irradiation beam, use a Faraday cup to monitor and control the dose of the irradiation beam, and use a quadrupole lens to defocus the radiation beam and achieve uniform radiation.

[0054] As an example, the step of using irradiation treatment in step S2 to make the capture rate of carriers by the internal traps of the epitaxial structure 200 less than the release rate can be a combination of proton irradiation treatment and ultraviolet irradiation treatment. First, the displacement effect of proton irradiation is used to introduce defects in the channel layer 230, and the tiny leakage current channel generated by the newly introduced defects is used to promote the release process of the captured carriers by the internal traps of the buffer layer 220. Then, the epitaxial structure of the irradiation treatment system is subjected to ultraviolet irradiation treatment, and the annealing effect of ultraviolet irradiation is used to repair the defects or damage caused by proton irradiation to the surface of the device. At the same time, the radiation energy of ultraviolet irradiation can also provide energy for the internal traps of the buffer layer 220 to release carriers, thereby promoting the release process of the internal traps of the buffer layer 220 to the captured carriers and reducing the capture rate of the internal traps of the buffer layer 220 for the carriers.

[0055] Among them, the irradiation treatment system also includes a second irradiation control component consisting of an ultraviolet detector and a beam homogenizer. The ultraviolet irradiation treatment uses an ultraviolet detector to monitor and control the intensity of the radiated ultraviolet light, and uses a beam homogenizer to defocus the radiated ultraviolet light and achieve uniform radiation.

[0056] In addition, the ambient gas for planar GaN devices during UV irradiation is O 3 , O 3 By using ultraviolet radiation to treat planar GaN devices in an environment, impurity molecules introduced during the preparation of planar GaN devices can be dissociated by ultraviolet radiation and oxidized by oxygen atoms to form volatile by-products, thereby achieving interface cleaning of planar GaN devices.

[0057] As an example, the step of using irradiation treatment in step S2 to make the capture rate of carriers by the internal traps of the epitaxial structure 200 less than the release rate can be a combination of multiple gradient proton irradiation treatments. First, the epitaxial structure 200 is subjected to proton irradiation treatment of a first energy threshold and a first dose threshold by the irradiation treatment system, and defects are introduced into the channel layer 230 by using the displacement effect of proton irradiation, and the tiny leakage current channel generated by the newly introduced defects is used to promote the release process of the captured carriers by the internal traps of the buffer layer 220. Then, the epitaxial structure 200 is subjected to proton irradiation treatment of a second energy threshold and a second dose threshold by the irradiation treatment system, and a large amount of space charge is introduced into the buffer layer 220 by using the ionization effect of proton irradiation. The space charge will affect the internal electric field distribution of the buffer layer 220, and the capture of carriers by the internal traps of the buffer layer 220 is shielded by the modulation of the electric field, and the internal traps of the buffer layer 220 are directly interacted with to make the traps reach a saturated state, thereby reducing the capture rate of carriers by the internal traps of the buffer layer 220.

[0058] As an example, Figure 3 As shown, the method for preparing a planar GaN device structure may include the following specific steps:

[0059] Step S1 - 0 is performed to provide a GaN device, where the GaN device includes a substrate and an epitaxial structure.

[0060] Execute step S1-1 to clean and oxidize the surface of the epitaxial structure.

[0061] Execute step S1-2 to form a passivation film on the surface of the epitaxial structure. The passivation film includes but is not limited to SiO 2 Passivation film.

[0062] Then, step S2-0 is performed to perform irradiation treatment with a preset dose and a preset energy on the epitaxial structure of the GaN device using the irradiation treatment system.

[0063] Step S2-1 is performed to remove the passivation film on the surface of the epitaxial structure by dry or wet etching, or chemical etching, and the exposed surface of the epitaxial structure is passivated, cleaned and dried. The passivation treatment technology does not include thermal annealing treatment to avoid high temperature processes that cause defects introduced by radiation to be repaired.

[0064] Step S3 is performed to form a P-type doped GaN film on the surface of the epitaxial structure, and the P-type doped GaN film is patterned and etched based on a chlorine-based ICP process to form a P-GaN layer.

[0065] Step S4 is performed to form a passivation layer on the epitaxial structure, and the passivation layer covers the surface of the epitaxial structure and encapsulates the P-GaN layer.

[0066] Step S5 is performed to etch the passivation layer to form a first window exposing a portion of the upper surface of the P-GaN layer, and a second window and a third window exposing a portion of the upper surface of the epitaxial structure, wherein the second window and the third window are located on both sides of the P-GaN layer, respectively.

[0067] Step S6 is performed to deposit metal in the second window and the third window respectively, so as to form an ohmic contact layer in the second window and the third window.

[0068] Step S7 is performed to perform ion implantation at the outer edges of the second window and the third window based on an ion implantation process to form an isolation region between adjacent cells in the GaN device.

[0069] Execute step S8 to contact the electrode based on a metal deposition process, including forming a gate electrode on the P-GaN layer exposed by the first window, forming a source electrode on the ohmic contact layer exposed by the second window, and forming a drain electrode on the ohmic contact layer exposed by the third window, the gate electrode forms a Schottky contact with the P-GaN layer, and the source electrode and the drain electrode form ohmic contacts with the surface of the epitaxial structure through the ohmic contact layer, respectively.

[0070] It should be noted that the present application does not specifically limit the direction in which the epitaxial structure is irradiated. Figure 3 In the embodiment, the direction of irradiating the epitaxial structure 200 by irradiation treatment is top irradiation treatment. However, the direction of irradiating the epitaxial structure 200 may include but is not limited to top irradiation treatment. For example, the epitaxial structure 200 may also be irradiated by bottom irradiation treatment or lateral irradiation treatment, and steps S1-2 and S2-1 may be omitted.

[0071] In addition, the specific types of GaN devices in the above embodiments are not specifically limited, including but not limited to enhancement mode devices (E-mode) and depletion mode devices (D-mode). Those skilled in the art only need to adapt the above process according to the specific device type. For example, the depletion mode device is omitted. Figure 3 The above step can be performed by referring to step S3, which will not be elaborated in detail here.

[0072] In other embodiments, Figure 4 As shown, when the GaN device is a vertical GaN device, controlling the irradiation treatment system to perform irradiation treatment on the vertical GaN device with a preset irradiation dose and a preset irradiation energy will produce a displacement effect at a preset position on the edge of the drift layer of the vertical GaN device (i.e., the edge terminal 331) and introduce new defects, thereby modulating the trap effect of the epitaxial structure 300 of the vertical GaN device, thereby increasing the resistivity of the drift layer at the edge terminal 331, promoting the lateral distribution of the device electric field, reducing the crowding effect caused by the concentration of the electric field, making the electric field more uniform, and improving the breakdown voltage of the vertical GaN device, thereby expanding the application of the irradiated vertical GaN device in the high voltage and high frequency fields.

[0073] As an example, the vertical gallium nitride epitaxial structure 300 may include a first gallium nitride layer 310 , a second gallium nitride layer 320 , and a third gallium nitride layer 330 sequentially stacked on the substrate 100 .

[0074] The first GaN layer 310 may be an N-type heavily doped layer (N +-GaN) to form an ohmic contact with the substrate 100. The second gallium nitride layer 320 and the third gallium nitride layer 330 are sequentially formed on the first gallium nitride layer 310, which may be unintentionally doped with gallium nitride and serve as drift layers of the epitaxial structure 300. Since the first gallium nitride layer 310, the second gallium nitride layer 320 and the substrate 100 have matching thermal expansion coefficients (CTE), the second gallium nitride layer 320 can grow to a relatively thick thickness and still maintain good crystalline quality. In other embodiments, the epitaxial structure 300 also includes an interface layer between the first gallium nitride layer 310 and the second gallium nitride layer 320, and the interface layer may include materials such as aluminum gallium nitride and indium gallium nitride. The third gallium nitride layer 330 is formed on the second gallium nitride layer 320, and includes an edge terminal 331 located at the edge, and a P-type heavily doped region 332 (P + -GaN). The edge terminal 331 and the P-type heavily doped region 332 may also be coupled to the drift layer, and a portion of the drift layer is converted and separated to form a third gallium nitride layer 330, for example, by injecting magnesium ions to dope and form a first edge terminal and a second edge terminal opposite to each other at the edge of the second gallium nitride. The anode 410 in the contact electrode is located on the P-type heavily doped region 332 and extends to cover a portion of the edge terminal 331, and the cathode 420 in the contact electrode is located on the side of the substrate 100 away from the epitaxial structure 300.

[0075] As an example, the step of using irradiation treatment to modulate the internal trap effect of the drift layer in step S2 is to perform electron irradiation treatment with preset energy and preset dose on the edge terminal 331 of the epitaxial structure 300, and introduce a large number of defects in the edge terminal 331 by utilizing the displacement effect of electron irradiation. The newly introduced defects combine with carriers to make the corresponding area of ​​the edge terminal 331 obtain a larger resistivity, promote the lateral distribution of the electric field of the epitaxial structure 300, reduce the concentration of the electric field, make the electric field uniform, and improve the breakdown voltage of the device.

[0076] In addition, the newly injected electrons themselves can temporarily participate in the conduction process of the device as carriers after entering the drift layer, replenishing the carrier concentration lost by the device, thereby reducing the on-resistance.

[0077] It should be noted that the term "layer" should be understood as a layer that may include multiple sub-layers that form a layer of interest. Therefore, the term "layer" is not intended to represent a single layer composed of a single material, but rather encompasses one or more materials that are layered in a composite manner to form a desired structure. A person of ordinary skill in the art may recognize a variety of variations, modifications, and substitutions.

[0078] According to a second aspect of the present application, a GaN device structure is further provided. The GaN device structure is prepared by the method for preparing the GaN device structure described in any one of the above embodiments.

[0079] In summary, the present application provides a GaN device structure and a method for preparing the same, including providing a GaN device, and then irradiating the GaN device with a preset dose and a preset energy. Through the irradiation treatment, defects are introduced into the epitaxial structure 300 of the GaN device, and the internal trap effect of the epitaxial structure is modulated, thereby modulating the electrical properties of the GaN device and expanding the application of the GaN device in the high voltage and high frequency fields.

[0080] When the GaN device is a planar GaN device, the irradiation treatment will make the capture rate of carriers by the internal traps of the epitaxial structure 300 lower than the release rate, so as to improve the dynamic resistance decay of the planar GaN device, thereby improving the operation stability and reliability of the planar GaN device. At the same time, the irradiation process will not damage other electrical properties of the planar GaN device, expanding the application of the irradiated planar GaN device in the high voltage and high frequency fields.

[0081] When the GaN device is a vertical GaN device, the irradiation treatment will introduce defects inside the epitaxial structure 300 and increase the resistivity of the epitaxial structure 300 at a preset irradiation position, promote the lateral distribution of the device electric field, reduce the electric field concentration, and make the electric field uniform, thereby increasing the breakdown voltage of the vertical GaN device and expanding the application of the irradiated vertical GaN device in the high voltage and high frequency fields.

[0082] In the description of the foregoing embodiments, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they contradict each other.

[0083] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. A method for preparing a gallium nitride device structure, characterized in that: The method includes providing a gallium nitride device, wherein the gallium nitride device includes a substrate and an epitaxial structure stacked in sequence; placing the gallium nitride device on an irradiation platform, and using an irradiation processing system to perform irradiation processing on the gallium nitride device with a preset dose and preset energy, so as to introduce defects in the epitaxial structure and modulate the trap effect of the epitaxial structure.

2. The preparation method according to claim 1, characterized in that: The radiation treatment system performs radiation treatment of a preset dose and a preset energy on the gallium nitride device, including one or more combinations of proton radiation treatment, electron radiation treatment and ultraviolet radiation.

3. The preparation method according to claim 2, characterized in that: The irradiation processing system also includes a first irradiation control component, which includes a silicon diode detector, a Faraday cup and a quadrupole lens. The proton irradiation processing and / or the electron irradiation processing uses a silicon diode detector to monitor the energy of the irradiation beam, uses a Faraday cup to monitor the dose of the irradiation beam, and uses a quadrupole lens to defocus the radiation beam and achieve uniform radiation.

4. The preparation method according to claim 2, characterized in that: The irradiation treatment system also includes a second irradiation control component, which includes an ultraviolet detector and a beam homogenizer. The ultraviolet irradiation treatment uses an ultraviolet detector to monitor the intensity of the radiated ultraviolet light, and uses a beam homogenizer to defocus the radiated ultraviolet light and achieve uniform radiation; wherein the ambient gas for the gallium nitride device to perform the ultraviolet irradiation treatment is O3.

5. The preparation method according to claim 2, characterized in that: When the gallium nitride device is a planar gallium nitride device, the epitaxial structure includes a buffer layer and a channel layer formed by sequentially stacking carbon intentionally doped gallium nitride and unintentionally doped gallium nitride; the step of modulating the trap effect of the epitaxial structure is to make the capture rate of carriers by internal traps of the buffer layer smaller than the release rate.

6. The preparation method according to claim 5, characterized in that: The step of using the radiation treatment system to perform radiation treatment on the gallium nitride device with a preset dose and preset energy includes: Performing the proton irradiation treatment on the epitaxial structure by the irradiation treatment system, and introducing defects in the channel layer by utilizing the displacement effect of the proton irradiation; Perform the electron irradiation treatment on the epitaxial structure by the irradiation treatment system, and introduce a large amount of space charges in the buffer layer by utilizing the ionization effect of the electron irradiation; or The epitaxial structure is subjected to the ultraviolet radiation treatment by the radiation treatment system, and the surface defects of the epitaxial structure are repaired by the ultraviolet radiation, and energy is provided for the internal traps of the buffer layer to release carriers.

7. The preparation method according to claim 5, characterized in that: The step of using the radiation treatment system to perform radiation treatment on the gallium nitride device with a preset dose and preset energy includes: Performing the proton irradiation treatment of a first energy threshold and a first dose threshold on the epitaxial structure by the irradiation treatment system, and introducing defects in the channel layer by utilizing the displacement effect of the proton irradiation; The proton irradiation treatment of a second energy threshold and a second dose threshold is performed on the epitaxial structure by the irradiation treatment system, and a large amount of space charges are introduced into the buffer layer by utilizing the ionization effect of the proton irradiation.

8. The preparation method according to claim 2, characterized in that: When the gallium nitride device is a vertical gallium nitride device, the epitaxial structure includes a drift layer composed of unintentionally doped gallium nitride on the substrate, and the step of modulating the trap effect of the drift layer by irradiation treatment increases the resistance of a preset position at the edge of the drift layer.

9. The preparation method according to claim 8, characterized in that: The step of using the radiation treatment system to perform radiation treatment on the gallium nitride device with a preset dose and preset energy includes: The electron irradiation treatment is performed on the preset edge position of the epitaxial structure by the irradiation treatment system, and a displacement effect of the electron irradiation is utilized to introduce defects into the preset edge position of the drift layer, so that the preset resistance of the edge of the drift layer is increased.

10. A gallium nitride device structure, characterized in that: The gallium nitride device structure is prepared by the method for preparing the gallium nitride device structure according to any one of claims 1 to 9.

Images