A bidirectional switch and electronic device

Abstract

This application provides a bidirectional switch and an electronic device. The bidirectional switch includes: a substrate, an active layer disposed on the substrate, and a barrier layer disposed on the active layer; a first gate, a second gate, a first source, and a second source disposed on a first surface of the barrier layer; at least one metal field plate structure, each of the at least one metal field plate structure including a first field plate and a second field plate; and at least one third field plate structure disposed above a first plane, with its projection onto the first plane located between the first gate and the second gate. The first plane is the plane containing the first surfaces of the first gate and the second gate. Each of the at least one third field plate structure includes at least one third field plate. By adding a third field plate structure, more high electric field regions are covered, weakening the electric field spikes between the gates and achieving electric field equalization.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically, to a bidirectional switch and electronic device. Background Technology

[0002] With the development of semiconductor technology, bidirectional switches have become an ideal choice for AC control, energy conversion, and high-frequency power electronics due to their bidirectional conduction capability, high efficiency, low loss, and simple structure. The application of bidirectional switches has been further expanded with the popularization of wide-bandgap semiconductors (such as silicon carbide or gallium nitride). However, bidirectional switches still suffer from uneven electric field distribution in high-frequency and high-voltage scenarios, leading to risks such as localized breakdown, thermal runaway, or shortened lifespan.

[0003] Therefore, how to achieve electric field balance in bidirectional switches is an urgent problem to be solved. Summary of the Invention

[0004] This application provides a bidirectional switch and electronic device, which can achieve electric field balance of the bidirectional switch by setting a third field plate structure.

[0005] In a first aspect, a bidirectional switch is provided, comprising: a substrate, an active layer disposed on the substrate, and a barrier layer disposed on the active layer; a first gate, a second gate, a first source, and a second source disposed on a first surface of the barrier layer, the first gate being disposed between the first source and the second gate, and the second gate being disposed between the first gate and the second source; at least one metal field plate structure, each metal field plate structure comprising a first field plate and a second field plate, one end of the first field plate being electrically connected to the first source, and one end of the second field plate being electrically connected to the second source; at least one third field plate structure disposed above a first plane, and the projection of the third field plate onto the first plane being located between the first gate and the second gate, the first plane being the plane containing the first surface of the first gate and the first surface of the second gate, and each third field plate structure comprising at least one third field plate.

[0006] It should be noted that the first surface in the embodiments of this application is the upper surface or the front surface. For example, "the first gate, the second gate, the first source and the second source disposed on the first surface of the barrier layer" can be understood as: the lower surfaces of the first gate, the second gate, the first source and the second source are in direct contact with the upper surface of the barrier layer; or it can also be understood as: there may be other layers between the barrier layer and the first gate, the second gate, the first source and / or the second source.

[0007] Optionally, the bidirectional switch may also include a buffer layer disposed between the substrate and the active layer, a nucleation layer disposed between the substrate and the buffer layer, a passivation layer disposed on the barrier layer (such as the surface of the barrier layer), and / or a spacer layer disposed on the barrier layer (which may at least partially cover the first gate and the second gate).

[0008] The material of the third field plate can include conductive materials such as titanium (Ti), tantalum (Ta), titanium nitride (TiN), and tantalum nitride (TaN), or it can be aluminum, copper-doped silicon, or alloys containing the above materials. Optionally, the material of the third field plate can further include low-resistivity materials, such as polycrystalline silicon and silicon-chromium compounds.

[0009] Based on the above solution, compared with traditional bidirectional switches, the bidirectional switch proposed in this application adds at least one third field plate structure to the access region between the two gates, which can cover more high electric field regions, weaken the electric field spikes between the gates, and avoid local breakdown. This improves the device's withstand voltage capability, reduces the impact of dynamic collapse effect, and shortens the spacing between the gates, further enabling devices (e.g., chips) including this bidirectional switch to have higher reliability and cost competitiveness.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, the bidirectional switch includes an N-layer metal field plate structure and an N-layer third field plate structure, wherein the i-th layer third field plate structure and the i-th layer metal field plate structure are disposed on the same layer, where N is a positive integer and i is a positive integer less than or equal to N.

[0011] In this configuration, a third field plate structure is correspondingly provided for each layer of the metal field plate structure. The electric field spikes between the first and second field plates in the same layer can be preferentially weakened by the third field plate, thus achieving better electric field equalization for the bidirectional switch. Since the third field plate structure and the metal field plate structure are located in the same layer, the field plates can be fabricated using a single mask, saving fabrication steps and reducing the fabrication complexity of the bidirectional switch. Furthermore, the same-layer structure can further compress space, allowing for higher integration density in the bidirectional switch.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the bidirectional switch includes an N-layer metal field plate structure and an M-layer third field plate structure, wherein the i-th third field plate structure and the j-th metal field plate structure are disposed on the same layer, wherein N and M are both positive integers, i is a positive integer less than or equal to M, j is a positive integer less than or equal to N, and M is less than or equal to N.

[0013] In this configuration, not every metal field plate structure corresponds to a third field plate structure, which reduces the fabrication complexity of the third field plate. Since the third field plate structure and the metal field plate structure are located on the same layer, the field plates on the same layer can be fabricated using a single mask, thus saving fabrication steps. Furthermore, the same-layer structure can further compress space, allowing for higher integration density in bidirectional switches.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, the third field plate structure of each layer includes at least one third field plate in a first direction and at least one third field plate in a second direction.

[0015] Regarding the first and second directions, please refer to... Figure 6 The relevant explanations are shown below.

[0016] Based on the above scheme, the number of third field plates included in each layer of the third field plate structure can be flexibly set so that the number of third field plates can be adapted to the specific application of bidirectional switches. For example, the number of layers of the third field plate structure and the number of third field plates in each layer can be determined according to the electric field strength in the access area (e.g., according to the electric field peaks presented in the access area, more third field plates can be set near the corresponding peak positions to achieve better electric field balance at the peak).

[0017] In conjunction with the first aspect, in some implementations of the first aspect, where the third field plate structure of each layer includes a third field plate in the first direction, the third field plate is a strip-shaped field plate extending along the first direction.

[0018] In conjunction with the first aspect, in some implementations of the first aspect, when the bidirectional switch includes a multi-layer third field plate structure, the projections of the third field plates included in at least two layers of the multi-layer third field plate structure onto the first plane at least partially overlap; or, the projections of the third field plates included in the multi-layer third field plate structure onto the first plane do not overlap.

[0019] Based on the above scheme, the position of the third field plate included in each layer of the third field plate structure can also be flexibly set, so that the position of the third field plate can be adapted to the specific application of bidirectional switches. For example, the number of layers of the third field plate structure and the position of the third field plate in each layer can be determined according to the electric field strength of the access area (e.g., according to the electric field peaks presented in the access area, the third field plate can be set near the corresponding peak position to achieve electric field equalization at the peak).

[0020] In conjunction with the first aspect, in some implementations of the first aspect, the projection shape of the third field plate onto the first plane includes a rectangle, a square, a circle, an ellipse, a spindle shape, and / or a polygon.

[0021] Based on the above scheme, the projection shape of the third field plate on the first plane has strong flexibility and is easy to adapt to industrial design and production. In conjunction with the first aspect, in some implementations of the first aspect, the bidirectional switch further includes: a dielectric layer disposed between the barrier layer and the at least one field plate structure, the dielectric layer encapsulating the at least one third field plate structure, and the material of the dielectric layer including silicon oxide, silicon nitride, or silicon oxynitride.

[0022] Based on the above scheme, the third field plate can form a multi-level capacitor network with the semiconductor surface through the dielectric layer, attracting or repelling surface charges step by step, so that the depletion region expands more uniformly laterally.

[0023] In conjunction with the first aspect, in some implementations of the first aspect, the bidirectional switch is a nitrogen-based bidirectional switch, the active layer is a nitrogen-based active layer, and the barrier layer is a nitrogen-based barrier layer.

[0024] In one possible implementation, gallium nitride (GaN) is epitaxially grown on a substrate. In order to achieve a high-quality GaN layer, aluminum nitride (AlN), aluminum gallium nitride (AlGaN), and a buffer layer of GaN can be grown before epitaxial growth of GaN to relieve stress and reduce dislocations.

[0025] In conjunction with the first aspect, in some implementations of the first aspect, the metal field plate structure and the third field plate structure disposed on the same layer are formed by etching the same layer material.

[0026] In this case, the same-layer metal field plate and the third field plate can be fabricated at the same time, reducing the complexity and time cost of the bidirectional switch fabrication process.

[0027] In a second aspect, a method for fabricating a bidirectional switch is provided, the method comprising: forming an active layer on a substrate; forming a barrier layer on the active layer; forming a first gate, a second gate, a first source, and a second source on a first surface of the barrier layer, the first gate being disposed between the first source and the second gate, and the second gate being disposed between the first gate and the second source; forming at least one metal field plate structure and at least one third field plate structure on the barrier layer, each of the at least one metal field plate structure comprising a first field plate and a second field plate, one end of the first field plate being electrically connected to the first source, one end of the second field plate being electrically connected to the second source, the at least one third field plate structure being disposed above a first plane, and the projection of the first plane being located between the first gate and the second gate, the first plane being the plane containing the first surface of the first gate and the first surface of the second gate, and each of the at least one third field plate structure comprising at least one third field plate.

[0028] In conjunction with the second aspect, in some implementations of the second aspect, the bidirectional switch includes an N-layer metal field plate structure and an M-layer third field plate structure. If the i-th third field plate structure and the j-th metal field plate structure are disposed on the same layer, N and M are both positive integers, i is a positive integer less than or equal to M, and j is a positive integer less than or equal to N. The formation of at least one metal field plate structure and at least one third field plate structure on the barrier layer includes: forming a first metal layer on the barrier layer; and patterning the first metal layer to form the i-th third field plate structure and the j-th metal field plate structure.

[0029] Based on the above scheme, since the third field plate structure and the metal field plate structure are located on the same layer, the field plates on the same layer can be fabricated using a single mask, reducing the fabrication complexity of the bidirectional switch. Furthermore, the same-layer structure can further compress space, allowing the bidirectional switch to have a higher integration density.

[0030] In conjunction with the second aspect, in some implementations of the second aspect, the bidirectional switch includes an N-layer metal field plate structure and an M-layer third field plate structure. If the p-th third field plate structure and the q-th metal field plate structure are disposed on different layers, N and M are both positive integers, p is a positive integer less than or equal to M, and q is a positive integer less than or equal to N. The formation of at least one metal field plate structure and at least one third field plate structure on the barrier layer includes: forming a second metal layer on the barrier layer; patterning the second metal layer to form the p-th third field plate structure; forming a third metal layer on the p-th third field plate structure; and patterning the third metal layer to form the q-th metal field plate structure.

[0031] Based on the two implementation methods of the second aspect, a more flexible fabrication method for metal field plate structures and third field plate structures is provided.

[0032] It should be noted that the beneficial effects of the second aspect and its corresponding implementation can be further described in the relevant description of the first aspect and its corresponding implementation, which will not be elaborated here.

[0033] Thirdly, an electronic device is provided, including a driving circuit, a filtering circuit, a control circuit, a power conversion circuit, and at least one bidirectional switch as in any possible implementation of the first aspect.

[0034] For example, the electronic device may be at least one of an inverter (such as a photovoltaic microinverter) and its energy storage system, an AC-AC motor drive, and / or a matrix converter. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a traditional transistor and a bidirectional switch.

[0036] Figure 2 This is a schematic diagram of the system architecture applicable to the embodiments of this application.

[0037] Figure 3 This is a structural schematic diagram of a bidirectional switch 300 applicable to an embodiment of this application.

[0038] Figure 4 This is a schematic diagram of the structure of the bidirectional switch 300A applicable to the embodiments of this application.

[0039] Figure 5 This is a structural schematic diagram of the bidirectional switch 300B applicable to embodiments of this application.

[0040] Figure 6 This is a schematic diagram of the structure of the bidirectional switch 300C applicable to embodiments of this application.

[0041] Figure 7 This is a structural schematic diagram of the bidirectional switch 300D applicable to embodiments of this application.

[0042] Figure 8 This is a schematic diagram of the shape of the third field plate projected onto the first plane, applicable to embodiments of this application.

[0043] Figure 9 This is a schematic diagram of a method for preparing a bidirectional switch applicable to embodiments of this application. Detailed Implementation

[0044] The technical solutions of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the scope of protection of this application.

[0045] To facilitate understanding of the embodiments of this application, the terms involved in this application will be briefly explained first.

[0046] 1. Bidirectional Switch (BDS)

[0047] A BDS (Block MOSFET) consists of two metal-oxide-semiconductor field-effect transistors connected in reverse series. It achieves bidirectional conduction (allowing current to flow in both forward and reverse directions), bidirectional blocking, and unidirectional conduction through a controlled gate. Its on / off state can be controlled by external signals (such as voltage or current). For example, when a control signal (such as gate voltage) is activated, the BDS allows current to flow in either direction; when the control signal is removed, the BDS blocks bidirectional current.

[0048] Figure 1 This is a schematic diagram of a traditional transistor and a bidirectional switch.

[0049] It should be understood that Figure 1 This is for illustrative purposes only and does not constitute a limitation on the structure of conventional transistors and bidirectional switches.

[0050] like Figure 1 As shown in (a), a conventional transistor includes a gate, a source, and a drain, and the breakdown voltage of the device is determined by the field plate combined with the region between the gate and the drain.

[0051] Optionally, the number of field plates depends on the voltage rating of the device, so the device may include any number of field plates, for example, it may include at least one field plate or none at all.

[0052] like Figure 1 As shown in (b), a BDS can include two gates and two sources, and the breakdown voltage of the device is determined by the area between the two gates combined with the field plates (such as S1FP1 and S2FP2). Unlike traditional transistors, BDS can handle bidirectional current without additional anti-parallel diodes, thereby reducing component count and circuit complexity. For example, BDS can eliminate the need for anti-parallel diodes, additional drive circuits, or isolation devices, reducing PCB area and cost. Furthermore, in complex topologies such as H-bridges and matrix converters, BDS can directly replace multiple sets of unidirectional switches, simplifying layout.

[0053] Furthermore, BDS, due to its low conduction loss characteristics (i.e., low on-resistance), can significantly reduce conduction losses in wide bandgap semiconductor devices such as silicon carbide (SiC) and gallium nitride (GaN).

[0054] In one implementation, the BDS may include a dual-gate transistor. This dual-gate transistor can be implemented using a pair of transistor elements connected in series, each transistor element including a source and a gate. When either gate is turned off, the transistor corresponding to that gate is turned off (i.e., charging or discharging operations can be terminated). In this case, the BDS may include at least one of the off transistor elements to act as a withstand voltage structure. If the withstand voltage provided by the BDS is sufficient, charging or discharging operations can be terminated to the BDS. However, if the withstand voltage provided by the BDS is poor, termination of charging or discharging operations to the BDS may fail, and the poor withstand voltage may be caused by breakdown in the BDS.

[0055] 2. Electric field equilibrium

[0056] Electric field equalization refers to the technique of uniformly distributing voltage or electric field across multiple devices or regions in power electronic systems or high-voltage equipment through design methods. Its core objective is to avoid localized electric field concentration (i.e., "electric field stress concentration"), thereby preventing device damage due to overvoltage and improving system reliability and efficiency.

[0057] Electric field imbalance may be caused by the following factors:

[0058] (1) Differences in device parameters: Even devices produced in the same batch may have slight differences in parasitic capacitance, threshold voltage or switching speed, resulting in uneven voltage distribution.

[0059] (2) Dynamic switching characteristics: During the switching transient process, the difference in the on / off time of the device will cause some devices to withstand higher instantaneous voltage.

[0060] (3) Asymmetrical layout: Asymmetrical distribution of PCB traces, parasitic inductance or capacitance may cause local concentration of electric field.

[0061] An imbalance in the electric field may lead to the following problems:

[0062] (1) Local breakdown: The voltage that the device withstands exceeds its rated value, causing avalanche breakdown or insulation failure.

[0063] (2) Thermal runaway: Devices in the high-voltage region overheat due to increased power consumption, which exacerbates parameter drift (such as an increase in on-resistance).

[0064] (3) Shortened lifespan: Electric field stress concentration accelerates device aging and reduces system reliability.

[0065] (4) Efficiency decline: Some devices enter the linear region due to overvoltage, resulting in increased conduction or switching losses.

[0066] Figure 2 This is a schematic diagram of the system architecture applicable to the embodiments of this application.

[0067] For ease of understanding, Figure 2 The application of BDS in a three-phase Vienna topology will be used as an example. A Vienna topology is a three-level rectifier consisting of three phase arms. A traditional three-phase Vienna topology comprises three unidirectional voltage sources and three load impedances, with each voltage source having a 120-degree phase difference. The three unidirectional voltage sources are connected to the center point of the three-phase transformer, and each load impedance is connected to the end of its respective phase. When the voltage sources and impedances in a three-phase Vienna topology are connected, three voltage waveforms are generated. When the phase of the voltage across the load impedance is the same as its resistance, the load impedance absorbs the maximum power, thus maximizing the generator output power of the three-phase Vienna topology.

[0068] like Figure 2 As shown, introducing BDS into the Vienna topology, replacing traditional unidirectional switches (such as IGBTs + diodes), enables bidirectional energy flow and more flexible topology reconfiguration. Specifically, each phase arm uses two BDS (or integrated BDS modules) to replace the original unidirectional switches and diodes. The bidirectional conduction of the BDS allows energy to flow from the grid to the load (rectification mode) or from the load to the grid (inverter mode), thereby reducing the number of diodes and lowering conduction losses to support regenerative braking energy feedback (such as electric vehicle charging stations) and / or integrated charging and discharging of energy storage systems.

[0069] It should be noted that, Figure 2 This is merely one example of BDS being applied to a three-phase Vienna topology. Three-phase Vienna topologies incorporating BDS may also include other circuit structures and / or components, and the embodiments of this application do not limit this.

[0070] In one implementation, BDS can also be applied to power electronic converter systems. For example, in a matrix converter, BDS can function as a switching element, directly implementing AC-AC frequency conversion and voltage regulation without an intermediate DC link. This simplifies the topology, reduces switching losses, and enables high-frequency control algorithms (such as space vector modulation). As another example, in a dual active bridge (DAB), BDS can be used in high-frequency isolated DC-DC converters, supporting bidirectional energy transfer (such as energy exchange between batteries and the grid), thereby supporting soft-switching technology, dynamic power control strategies, and wide voltage range adaptation.

[0071] In one implementation, BDS can also be applied to motor drive and regenerative braking systems. For example, in an H-bridge motor drive circuit, BDS can replace the traditional "MOSFET + diode" combination, simplifying motor forward and reverse control, improving efficiency, and thus enabling integrated drive modules and sensorless control technology. As another example, in an electric vehicle regenerative braking system, BDS can be applied to energy recovery circuits to feed braking energy back to the battery, thereby enabling rapid switching control and / or multi-mode energy management.

[0072] In one implementation, BDS can also be applied to new energy and energy storage systems. For example, in photovoltaic inverters (PV Inverters), BDS can enable bidirectional energy flow between the DC and AC sides, supporting grid-fed and off-grid operation. As another example, in battery energy storage systems (BESS), BDS can be used for battery charge and discharge management, achieving seamless switching of charge and discharge paths, and can further realize multi-battery pack balancing control and / or fault isolation protection.

[0073] In one implementation, BDS can also be applied to solid-state circuit breakers. For example, in a solid-state circuit breaker (SSCB), BDS can serve as a fast switching element, supporting bidirectional fault current interruption (such as DC microgrid short-circuit protection), implementing ultra-fast shutdown algorithms and / or self-powered drive circuits.

[0074] In one implementation, BDS can also be applied to smart grids. For example, multi-port energy routers can be built based on BDS to flexibly allocate distributed energy resources and achieve multi-objective optimization control and / or dynamic topology reconfiguration.

[0075] It should be noted that the bidirectional switch in this application embodiment can be applied to any of the devices and / or systems shown above.

[0076] It should be understood that the system architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of system architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0077] With the development of semiconductor technology, bandgap semiconductor devices (BDS) have become an ideal choice for AC control, energy conversion, and high-frequency power electronics due to their bidirectional conductivity, high efficiency, low loss, and simple structure. The application of BDS has been further expanded with the popularization of wide-bandgap semiconductors (such as silicon carbide or gallium nitride). However, in high-frequency and high-voltage scenarios, BDS still suffers from uneven electric field distribution, leading to risks such as localized breakdown, thermal runaway, or shortened lifespan.

[0078] For example, based on the traditional BDS structure, the distance between the two gates can be increased to balance the electric field, but this method will increase the cell design size of the BDS, affecting the chip's cost competitiveness and reliability.

[0079] For example, a metal layer and two diodes can be incorporated into the BDS device. The cathodes of the two diodes are connected to different sources of the BDS, and the anodes of the two diodes are connected to the two ends of the metal layer. During BDS switching, the diodes can clamp the metal plate at the low-voltage source (i.e., the voltage across the metal plate is approximately 0V + V). f V f This is the diode's forward voltage, so the voltage potential of the metal plate will most likely remain between 1-3V. However, this method cannot truly achieve a 0V ground for the metal plate; there is a V0 potential difference between the metal plate and the low potential of the source. fThe voltage difference. Furthermore, during high-frequency switching of the device, the parasitic capacitance and current-carrying capacity of the diode may also affect the stability of the metal layer in maintaining a low potential.

[0080] In view of this, this application proposes a bidirectional switch that achieves electric field balance by setting electric field spikes in the floating field plate equalization device.

[0081] Figure 3 This is a structural schematic diagram of a bidirectional switch 300 applicable to an embodiment of this application.

[0082] like Figure 3 As shown, the bidirectional switch 300 includes a substrate, an active layer, a barrier layer, a first gate, a second gate, a first source, a second source, a metal field plate structure, and a third field plate structure, which will be described in detail below.

[0083] It should be understood that Figure 3 The structural schematic diagram corresponds to the front view of the bidirectional switch 300. In other words, the structural schematic diagram reflects that the various components of the bidirectional switch 300 are formed in layers for viewing along a direction parallel to these layers.

[0084] It should be noted that the first surface in the embodiments of this application is the upper surface or the front surface. For example, "the first gate, the second gate, the first source, and the second source disposed on the first surface of the barrier layer" can be understood as: the first gate, the second gate, the first source, and the second source are disposed on the upper surface of the barrier layer, that is, the lower surfaces of the first gate, the second gate, the first source, and the second source are in direct contact with the upper surface of the barrier layer; or it can be understood as: the first gate, the second gate, the first source, and the second source are disposed on the front surface of the barrier layer, and the barrier layer can be directly connected to the first gate, the second gate, the first source, and / or the second source, or other layers may exist. For example, the first gate and the second gate can be junction gates. In one implementation, p-type GaN can also be disposed below the first gate and the second gate (i.e., above the barrier layer, or between the barrier layer and the first gate, or between the barrier layer and the second gate). Thus, the p-type GaN layer below the gate can be used to raise the barrier at the channel, thereby depleting the two-dimensional electron gas (2DEG) in the channel to achieve normally-off operation.

[0085] A substrate is disposed at the bottom layer of the bidirectional switch 300. The substrate can be a semiconductor, used to provide mechanical support for the semiconductor device and as a substrate for epitaxial growth. The substrate material can include silicon (Si), silicon germanium (SiGe), silicon carbide (SiC), gallium arsenide, p-type doped silicon, n-type doped silicon, sapphire, and / or semiconductor-on-insulator (e.g., silicon-on-insulator, SOI) etc.

[0086] Alternatively, the substrate material may also include group III elements, group IV elements, group V elements, or combinations thereof (e.g., group III-V compounds).

[0087] Optionally, the substrate may also include a doped region, a buried layer, an epitaxial (epi) layer, etc.

[0088] In one possible implementation, gallium nitride (GaN) can be epitaxially grown on the substrate surface (e.g., GaN as an active layer).

[0089] The active layer, disposed on the substrate, is a functional layer in semiconductor devices where key carrier behaviors (such as migration, recombination, and confined motion) occur. It can form heterojunctions or quantum structures with other layers (such as barrier layers or buffer layers) to achieve specific electrical or optical functions. The materials of the active layer can include nitrides or III-V compounds (such as GaN, aluminum nitride (AlN), and / or indium nitride (InN)).

[0090] Optionally, the active layer may include a channel layer, which forms a 2DEG with high electron mobility, serving as a conductive channel and the core region for carrier transport. For example, the active layer may be made of undoped GaN.

[0091] A barrier layer is disposed on the active layer to form a heterojunction with the active layer. It induces a 2DEG through piezoelectric polarization and spontaneous polarization effects, achieving high conductivity. The barrier layer material can include aluminum gallium nitride (AlGaN) and / or AlN, etc.

[0092] Alternatively, the materials of the active layer and the barrier layer can be selected such that the band gap (i.e., the forbidden band width) of the barrier layer is larger than that of the active layer. In this case, since the active layer and the barrier layer have different electron affinities, a heterojunction can be formed between them.

[0093] For example, the active layer is an undoped gallium nitride layer (band gap of approximately 3.4 eV), and the barrier layer is an AlGaN layer (band gap of approximately 4 eV). Due to the difference in their band gaps, a triangular well potential is generated at the interface between the active and barrier layers, causing electrons to accumulate in the triangular well potential, thereby generating a two-dimensional electron gas (2DEG) region adjacent to the heterojunction. Therefore, the bidirectional switch 300 may include at least one gallium nitride-based high-electron-mobility transistor (HEMT).

[0094] In one possible implementation, the bidirectional switch 300 is a nitrogen-based bidirectional switch, with its active layer being a nitrogen-based active layer and / or its barrier layer being a nitrogen-based barrier layer.

[0095] A first gate is disposed on the first surface of the barrier layer. The first gate structure may include a gate electrode #1 and a semiconductor layer #1 (e.g., a p-type doped III-V compound semiconductor layer). The semiconductor layer #1 and the gate electrode #1 are stacked sequentially on the first surface of the barrier layer (e.g., the semiconductor layer is disposed between the gate electrode and the barrier layer). Optionally, a dielectric layer may also be disposed on the semiconductor layer #1 and the gate electrode #1.

[0096] The second gate is also disposed on the first side of the barrier layer. The structure of the second gate is similar to that of the first gate (e.g., it may include gate electrode #2 and semiconductor layer #2). The embodiments of this application will not be described in detail here.

[0097] Optionally, the bidirectional switch 300 is an enhancement-mode device, which is normally-off when gate electrodes #1 and #2 are applied with approximately zero bias. Specifically, semiconductor layers #1 and #2 can form at least one pn junction with the barrier layer to deplete the 2DEG region, thereby causing at least a portion of the 2DEG region located below the first and second gates to have different characteristics (e.g., different electron concentrations) than the rest of the 2DEG region, and thus be blocked.

[0098] The first source electrode and the second source electrode are disposed on the first surface of the barrier layer, and the first source electrode and the second source electrode are respectively located on opposite sides of the first gate electrode and the second gate electrode (i.e., the first gate electrode is disposed between the first source electrode and the second gate electrode, and the second gate electrode is disposed between the first gate electrode and the second source electrode). The materials of the first source electrode and the second source electrode may include metals, alloys, doped semiconductor materials (e.g., doped crystalline silicon), compounds (e.g., silicides and nitrides), or other conductive materials. For example, they may be titanium (Ti), aluminum silicon (AlSi), and / or titanium nitride (TiN), etc. The first source electrode and the second source electrode may be a single layer or a multilayer with the same or different compositions, which is not limited in the embodiments of this application. The first source electrode and the second source electrode may be a single layer or a multilayer with the same or different compositions. In some embodiments, the first source electrode and the second source electrode may form an ohmic contact with the barrier layer.

[0099] It should be noted that, in Figure 3 In the illustrated structure, the source (first source and second source) can be symmetrical with respect to the gate (first gate and second gate); in some implementations, the source can also be asymmetrical with respect to the gate, which is not limited in this embodiment. The gate and source can together serve as a dual-gate transistor with a 2DEG region.

[0100] The bidirectional switch 300 further includes at least one layer of metal field plate structure. Each layer of the metal field plate structure includes a first field plate and a second field plate (the first and second field plates of each layer are arranged opposite to each other). One end of the first field plate is electrically connected to the first source, and one end of the second field plate is electrically connected to the second source. It should be understood that the metal field plate structure can affect the voltage of the electronic device. In some cases, the more layers of the metal field plate structure, the easier it is to regulate the voltage of the bidirectional switch 300. The embodiments of this application do not limit the number of layers of the metal field plate structure. It should be noted that when the bidirectional switch device 300 is in the off state, whether breakdown occurs in the region between the first gate and the second gate is related to the electric field distribution in that region. The material of the metal field plate can include conductive materials such as Ti, tantalum (Ta), TiN, and tantalum nitride (TaN), or aluminum, copper-doped silicon, and alloys including the above materials.

[0101] Alternatively, the material of the metal field plate may further include low-resistivity materials, such as polycrystalline silicon, silicon-chromium (Cr) compounds, etc.

[0102] Optionally, for metal field plate structures of different layers, the projections of the corresponding different first field plates on the first plane overlap at least partially, and the projections of the corresponding different second field plates on the first plane overlap at least partially, wherein the first plane is the plane containing the first surface of the first gate and the first surface of the second gate.

[0103] In one possible implementation, the projection of the upper metal field plate structure onto the first plane overlaps the projection of the lower metal field plate structure onto the first plane. In this case, the distance between the first and second field plates in the upper metal field plate structure is smaller than the distance between the first and second field plates in the lower metal field plate structure. Therefore, the electric field distribution in the region between the first and second gates can be suppressed (making the electric field distribution in the region between the first and second gates smooth) and avoiding electric field peaks.

[0104] Optionally, for metal field plate structures of different layers, the projections of the corresponding different first field plates on the first plane do not overlap, and the projections of the corresponding different second field plates on the first plane do not overlap.

[0105] It should be noted that for information regarding the structure, materials, and other related aspects of the substrate, active layer, barrier layer, gate, source, and metal field plate, further reference can be made to the descriptions in the prior art, which will not be repeated here in the embodiments of this application.

[0106] The bidirectional switch 300 also includes at least one third field plate structure disposed above the first plane, and the projection of the third field plate structure onto the first plane is located between the first gate and the second gate. Each third field plate structure in the at least one third field plate structure includes at least one third field plate.

[0107] Since the third field plate does not contact the barrier layer, it can also be called a floating field plate. In this application, the name of the third field plate is not limited, and it will be described as the third field plate in the following description.

[0108] The material of the third field plate can include conductive materials such as Ti, Ta, TiN, and TaN, or aluminum, copper-doped silicon, and alloys containing the above materials. Optionally, the material of the third field plate can further include low-resistivity materials, such as polycrystalline silicon and silicon-chromium compounds.

[0109] Compared to traditional bidirectional switches, adding at least one third field plate structure to the access region between the two gates can cover more high electric field areas, weaken the electric field spikes between the gates, and avoid local breakdown. This improves the device's withstand voltage capability while reducing the impact of dynamic collapse effects, allowing for a shorter gate spacing. This further enhances the reliability and cost competitiveness of devices (e.g., chips) including the bidirectional switch 300.

[0110] Optionally, for a metal field plate structure in at least one layer of the metal field plate structure, a third field plate structure disposed on the same layer may exist. Thus, an optional method for fabricating the bidirectional switch 300 includes: the metal field plate structure and the third field plate structure disposed on the same layer are formed by etching the same layer material. In this case, the same-layer metal field plate and the third field plate can be fabricated in one step using only a single mask, without the need for additional photolithography steps, reducing the complexity and time cost of the bidirectional switch fabrication process. Furthermore, the same-layer structure can further compress space, allowing the bidirectional switch to have a higher integration density.

[0111] For example, if the bidirectional switch 300 includes two metal field plate structures and two third field plate structures (from bottom to top: metal field plate structure #1, third field plate structure #1 disposed on the same layer as metal field plate structure #1, metal field plate structure #2, and third field plate structure #2 disposed on the same layer as metal field plate structure #2, i.e., each metal field plate structure has a third field plate structure in the same layer), then metal field plate structure #1 and third field plate structure #1 can be formed on the first gate and the second gate using photolithography, and metal field plate structure #2 and third field plate structure #2 can be formed on the metal field plate structure #1 and third field plate structure #1. The two metal field plate structures and the two third field plate structures correspond to two metal layers. Optionally, for a certain metal field plate structure in at least one metal field plate structure, a third field plate structure disposed on the same layer as it may not exist. Thus, an optional method for fabricating the bidirectional switch 300 includes: forming metal field plate structures and / or third field plate structures sequentially above the first gate and the second gate in a bottom-up order. For example, a third field plate structure may not exist in the same layer as a certain metal field plate structure, but a third field plate structure may exist in the upper or lower layer adjacent to that metal field plate, or a third field plate structure may not exist in the upper or lower layer adjacent to that metal field plate.

[0112] For example, if the bidirectional switch 300 includes two layers of metal field plate structures and two layers of third field plate structures (from bottom to top, these are metal field plate structure #1, third field plate structure #1, metal field plate structure #2, and third field plate structure #2, i.e., there is a third field plate structure below each metal field plate structure), then metal field plate structure #1 can be formed first on the first gate and the second gate, third field plate structure #1 can be formed on the metal field plate structure #1, metal field plate structure #2 can be formed on the third field plate structure #1, and then third field plate structure #2 can be formed on the metal field plate structure #2. These two layers of metal field plate structures and two layers of third field plate structures correspond to four metal layers.

[0113] For example, if the bidirectional switch 300 includes two metal field plate structures and two third field plate structures (from bottom to top, they are third field plate structure #1, metal field plate structure #1, third field plate structure #2, and metal field plate structure #2, i.e., there is a third field plate structure above each metal field plate structure), then the third field plate structure #1 can be formed first on the first gate and the second gate, the metal field plate structure #1 can be formed on the third field plate structure #1, the third field plate structure #2 can be formed on the metal field plate structure #1, and then the metal field plate structure #2 can be formed on the third field plate structure #2. These two metal field plate structures and two third field plate structures correspond to four metal layers.

[0114] It should be noted that the pattern of each field plate structure can be obtained based on photolithography.

[0115] Optionally, the number of layers of the metal field plate structure included in the bidirectional switch 300 can be the same as the number of layers of the third field plate structure. That is, for each layer of the metal field plate structure, a corresponding third field plate structure is provided (for example, the third field plate structure can be provided in the same layer as a certain metal field plate structure; or the third field plate structure can be provided in the upper or lower layer adjacent to a certain metal field plate structure). In this case, the electric field spike between the first and second field plates in the same layer can be preferentially weakened by the third field plate in the same layer, thereby better achieving electric field balance for the bidirectional switch.

[0116] Optionally, the number of layers of the metal field plate structure included in the bidirectional switch 300 may be different from the number of layers of the third field plate structure. That is, not every layer of the metal field plate structure is provided with a corresponding third field plate structure. The number of layers of the third field plate structure is less than or equal to the number of layers of the metal field plate structure.

[0117] The optional implementations shown above can be combined to form different structures of the bidirectional switch 300. The embodiments of this application do not limit the combination of the optional implementations.

[0118] In one possible implementation, the number of layers of the metal field plate structure is the same as the number of layers of the third field plate structure (i.e., a third field plate structure is set for each layer of the metal field plate structure), and each layer of the metal field plate structure and one layer of the third field plate structure are set on the same layer.

[0119] For example, the bidirectional switch 300 may include an N-layer metal field plate structure and an N-layer third field plate structure, wherein the i-th layer third field plate structure and the i-th layer metal field plate structure are disposed on the same layer, where N is a positive integer and i is a positive integer less than or equal to N.

[0120] Figure 4 This is a schematic diagram of the structure of the bidirectional switch 300A applicable to the embodiments of this application.

[0121] like Figure 4 As shown, the bidirectional switch 300A includes two layers of metal field plate structures (metal field plate structure #1 and metal field plate structure #2), and each layer of metal field plate structure has a third field plate structure (third field plate structure #1 and third field plate structure #2) disposed on the same layer. It should be understood that... Figure 4 This is for illustrative purposes only and does not constitute a limitation on the number of layers of the metal field plate structure, the number of layers of the third field plate structure, or the number of third field plates that each layer of the third field plate structure may include in the bidirectional switch of this application embodiment.

[0122] In another possible implementation of the optional implementation shown above, the number of layers of the metal field plate structure and the number of layers of the third field plate structure are different (i.e., the third field plate structure is not set for every layer of metal field plate structure), and the metal field plate structure with the corresponding third field plate structure and the corresponding third field plate structure are set on the same layer.

[0123] For example, the bidirectional switch 300 includes an N-layer metal field plate structure and an M-layer third field plate structure, wherein the i-th third field plate structure and the j-th metal field plate structure are disposed on the same layer, wherein N and M are both positive integers, i is a positive integer less than or equal to M, j is a positive integer less than or equal to N, and M is less than or equal to N.

[0124] Figure 5 This is a structural schematic diagram of the bidirectional switch 300B applicable to embodiments of this application.

[0125] like Figure 5 As shown in (a), the bidirectional switch 300B includes two layers of metal field plate structures (metal field plate structure #1 and metal field plate structure #2), and the top layer of metal field plate structure has a third field plate structure (third field plate structure #1) disposed on the same layer. Figure 5 As shown in (b), the bidirectional switch 300B includes a two-layer metal field plate structure, and the bottom metal field plate structure has a third field plate structure (third field plate structure #1) disposed on the same layer. It should be understood that... Figure 5 This is for illustrative purposes only and does not constitute a limitation on the number of layers of the metal field plate structure, the number of layers of the third field plate structure, the number of third field plates that each layer of the third field plate structure may include, or the number and position of the metal field plates that are correspondingly provided with the third field plate structure in the embodiments of this application.

[0126] Optionally, when the bidirectional switch 300 includes a multilayer third field plate structure, the projections of the third field plates of at least two layers in the multilayer third field plate structure onto the first plane at least partially overlap. Alternatively, the projections of the third field plates of the multilayer third field plate structure onto the first plane do not overlap. (The following is in conjunction with...) Figure 6 Please provide an explanation.

[0127] Figure 6 This is a schematic diagram of the structure of the bidirectional switch 300C applicable to embodiments of this application.

[0128] For ease of understanding, Figure 6 The following description uses a bidirectional switch comprising two layers of metal field plate structures (field plate #1 and field plate #2), and each layer of metal field plate structure having a third field plate structure (third field plate structure #1 and third field plate structure #2) on the same layer. This does not constitute a limitation on the position and number of at least two layers of third field plates that at least partially overlap or do not overlap on the first plane in the embodiments of this application.

[0129] Figure 6 (a) is a possible structural schematic diagram of the bidirectional switch 300C. At least one third field plate included in the third field plate structure #1 and at least one third field plate included in the third field plate structure #2 are aligned in both the first and second directions, so that the projections of the third field plates included in the third field plate structure #1 and the third field plate structure #2 on the first plane completely overlap.

[0130] Figure 6 (b) is a possible structural schematic diagram of the bidirectional switch 300C. At least one third field plate included in the third field plate structure #1 and at least one third field plate included in the third field plate structure #2 are aligned in the first direction and partially staggered in the second direction, so that the projections of the third field plates included in the third field plate structure #1 and the third field plate structure #2 on the first plane partially overlap.

[0131] Figure 6 (c) is a possible structural schematic diagram of the bidirectional switch 300C. At least one third field plate included in the third field plate structure #1 and at least one third field plate included in the third field plate structure #2 are partially staggered in the first direction and aligned in the second direction, so that the projections of the third field plates included in the third field plate structure #1 and the third field plate structure #2 on the first plane partially overlap.

[0132] Figure 6 (d) is a possible structural schematic diagram of the bidirectional switch 300C. At least one third field plate included in the third field plate structure #1 and at least one third field plate included in the third field plate structure #2 are partially staggered in both the first and second directions, so that the projections of the third field plates included in the third field plate structure #1 and the third field plate structure #2 on the first plane partially overlap.

[0133] Figure 6(e) is a possible structural schematic diagram of the bidirectional switch 300C. At least one third field plate included in the third field plate structure #1 and at least one third field plate included in the third field plate structure #2 are aligned in the first direction and are completely staggered in the second direction, so that the projections of the third field plates included in the third field plate structure #1 and the third field plate structure #2 on the first plane do not overlap at all.

[0134] Figure 6 (f) is a possible structural schematic diagram of the bidirectional switch 300C. At least one third field plate included in the third field plate structure #1 and at least one third field plate included in the third field plate structure #2 are completely staggered in the first direction and aligned in the second direction, so that the projections of the third field plates included in the third field plate structure #1 and the third field plate structure #2 on the first plane do not overlap at all.

[0135] Figure 6 (g) is a possible structural schematic diagram of the bidirectional switch 300C. At least one third field plate included in the third field plate structure #1 and at least one third field plate included in the third field plate structure #2 are completely staggered in the first direction and in the second direction, so that the projections of the third field plates included in the third field plate structure #1 and the third field plate structure #2 on the first plane do not overlap at all.

[0136] It should be understood that Figure 6 Only partial possible structures of third field plate structures #1 and #2 are shown, and this does not constitute a limitation on the positional relationship of the third field plate structures of different layers in the embodiments of this application. For example, the third field plates included in third field plate structures #1 and #2 can also be rotated (i.e., any one of the third field plates may not be perpendicular to the gate, but rather form a certain angle with it). For another example, Figure 6 The third field plates shown are all distributed along the second direction as "dashed lines". The third field plates can also be distributed along the second direction as "solid lines". This will be discussed in the following text. Figure 7 A detailed explanation of "dashed lines" and "solid lines" is provided.

[0137] In one possible implementation, the position of the third field plate in each layer of the third field plate structure can be flexibly set according to the specific application of the bidirectional switch. For example, the number of layers of the third field plate structure and the position of the third field plate in each layer can be determined according to the electric field strength in the access area (e.g., a third field plate can be set near the corresponding peak position to achieve electric field equalization at the peak position according to the electric field peak presented in the access area).

[0138] Optionally, each layer of the third-field plate structure includes at least one third-field plate in a first direction and at least one third-field plate in a second direction. (The following is in conjunction with...) Figure 7 Please provide an explanation.

[0139] Figure 7 This is a structural schematic diagram of the bidirectional switch 300D applicable to embodiments of this application.

[0140] Figure 7 This is a top view of the 300D bidirectional switch. It should be understood that... Figure 7 This is merely an illustration of one possible third field plate structure in a bidirectional switch and does not constitute a limitation on the number of metal field plate structures, the number of third field plate structures, the number of third field plates that each third field plate structure may include, or the number and position of the metal field plates that are correspondingly provided with the third field plate structure in the embodiments of this application.

[0141] like Figure 7 As shown in (a), the third field plate structure of the bidirectional switch D can include a third field plate in the first direction, which is a strip-shaped field plate extending along the first direction. That is, in each third field plate structure, the third field plates can be distributed in a "solid line" along the first direction. As a possible implementation, Figures 4 to 6 All of the main views shown can be Figure 7 The cross-sectional view of the bidirectional switch 300D cut along cut-1 in (a) of the image.

[0142] like Figure 7 As shown in (b), the third-field plate structure of the bidirectional switch D can include multiple third-field plates in the first direction. That is, in each third-field plate structure, the third-field plates can be distributed along the first direction in a "dashed" pattern, so that the cross-sectional view of the bidirectional switch C cut along cut-3 does not include the third-field plates. As a possible implementation, Figures 4 to 6 All of the main views shown can be Figure 7 (b) Cross-sectional view of the bidirectional switch 300D cut along cut-2.

[0143] It should be noted that the third field plate structure in each layer is similar to the third field plate in the second direction as in the first direction, and will not be described in detail in the embodiments of this application.

[0144] In one possible implementation, the number of third field plates included in each layer of the third field plate structure can be flexibly set according to the specific application of the bidirectional switch. For example, the number of layers of the third field plate structure and the number of third field plates in each layer can be determined based on the electric field strength in the access area (e.g., more third field plates can be placed near the corresponding peak position to achieve better electric field balance at the peak position based on the electric field peak presented in the access area). Optionally, the projection of any third field plate included in any layer of the third field plate structure onto the first plane can include various shapes.

[0145] For example, such as Figure 8As shown, the shape of the third field plate can include rectangles, squares, circles, ellipses, spindles, and / or polygons, or other shapes. In this case, the projection shape of the third field plate onto the first plane has great flexibility and is easy to adapt to industrial design and production.

[0146] Furthermore, in the case where each layer of the third field plate structure in the at least one layer of the bidirectional switch 300 includes multiple third field plates, the embodiments of this application do not limit the projection shape of the multiple third field plates to be the same on the first plane. In one possible implementation, the third field plates in the same layer may have the same projection shape on the first plane.

[0147] It should also be noted that the embodiments of this application do not limit the size, spacing, number, material, and thickness of the third field plate in each layer of the third field plate structure.

[0148] Optionally, the bidirectional switch 300 may further include a dielectric layer disposed between the barrier layer and the at least one field plate structure (including a metal field plate structure and / or a third field plate structure), wherein the dielectric layer encapsulates the at least one third field plate structure, and the material of the dielectric layer includes silicon oxide, silicon nitride, or silicon oxynitride. Optionally, in some implementations, the dielectric layer may also serve as a passivation layer and / or a spacer layer, as described below, and will not be repeated here.

[0149] In addition, the bidirectional switch 300 may also include other layers or structures, as can be seen from the relevant descriptions in the prior art, and the embodiments of this application are not limited thereto.

[0150] Optionally, the bidirectional switch 300 may also include a buffer layer. The buffer layer may be disposed between the substrate and the active layer to alleviate lattice mismatch between the substrate and the epitaxial layer (such as the active layer), reduce defects, and improve crystal quality. The material of the buffer layer may include GaN, AlN, AlGaN, and / or aluminum indium gallium nitride (InAlGaN), etc.

[0151] In one possible implementation, GaN is epitaxially grown on a substrate, and in order to achieve a high-quality GaN layer, a buffer layer of AlN, AlGaN, and GaN can be grown first before epitaxial growth of GaN to relieve stress and reduce dislocations.

[0152] Optionally, the bidirectional switch 300 may also include a nucleation layer. The nucleation layer may be disposed between the substrate and the buffer layer to accommodate (or transition) the mismatch / difference between the group III nitride layers of the substrate and the buffer layer. The material of the nucleation layer may include AlN and / or any alloy thereof.

[0153] Optionally, the bidirectional switch 300 may also include a passivation layer. The passivation layer may be disposed on the barrier layer (such as the surface of the barrier layer) to protect the surface and reduce interface states and current collapse effects. The material of the passivation layer may include silicon nitride (SiNx) and / or silicon oxide (SiOx), etc.

[0154] Optionally, the bidirectional switch 300 may further include a spacer layer. The spacer layer may be disposed on a barrier layer and may at least partially cover the first gate and the second gate. The spacer layer may be used to protect the bidirectional switch 300, or it may be used to provide electrical isolation between different layers / elements to enhance the electrical characteristics of the device. The material of the spacer layer may include SiNx, SiOx, silicon nitride (Si3N4), silicon oxynitride (SiON), silicon carbide (SiC), silicon boron nitride (SiBN), silicon carbide silicon boron nitride (SiCBN), oxides, and / or nitrides. Optionally, the spacer layer may also be a multilayer structure, thereby being a composite dielectric layer comprising at least one material.

[0155] Figure 9 This is a schematic diagram of a method for preparing a bidirectional switch applicable to embodiments of this application.

[0156] based on Figure 9 The preparation method can obtain, for example Figures 3-7 Any of the bidirectional switches shown in the figure.

[0157] S901: An active layer is formed on the substrate.

[0158] For example, an active layer can be formed on the substrate surface by epitaxial growth (optionally, the active layer can be a nitrogen-based active layer, and the material of the active layer includes GaN).

[0159] S902: A barrier layer is formed on the active layer.

[0160] For example, a barrier layer can be formed on the surface of the active layer by epitaxial growth (optionally, the barrier layer can be a nitrogen-based barrier layer, and the material of the barrier layer includes AlGaN).

[0161] S903: A first gate, a second gate, a first source, and a second source are formed on the first surface of the barrier layer.

[0162] The first gate is disposed between the first source and the second gate, and the second gate is disposed between the first gate and the second source.

[0163] For example, source metal can be deposited using electron beam evaporation technology, and a low-resistance ohmic contact can be formed through rapid annealing. The first and second source electrodes are formed on opposite sides of the barrier layer, and the distance between the first and second source electrodes can be adjusted according to the device's voltage withstand requirements.

[0164] For example, after coating with photoresist, the gate region can be defined on the surface of the barrier layer using photolithography techniques (such as electron beam lithography or deep ultraviolet lithography). Specifically, for conventional HEMTs, gate metal can be deposited using electron beam evaporation to form a Schottky contact, thereby achieving an electric field-controlled 2DEG; for enhancement-mode HEMTs, a p-type GaN layer can be further epitaxially grown outside the gate region to form a pn junction gate, achieving normally-off characteristics.

[0165] Optionally, before forming the first and second gates, the barrier layer can be partially etched down to the active layer to enhance the gate's control over the 2DEG and reduce the threshold voltage. After etching, the gate metal can directly contact GaN to form a more efficient Schottky barrier and improve transconductance.

[0166] S904: At least one metal field plate structure and at least one third field plate structure are formed on the barrier layer.

[0167] Each of the at least one layer of metal field plate structures includes a first field plate and a second field plate. One end of the first field plate is electrically connected to the first source electrode, and one end of the second field plate is electrically connected to the second source electrode. The at least one layer of third field plate structure is disposed above a first plane, and its projection on the first plane is located between the first gate and the second gate. The first plane is the plane containing the first surface of the first gate and the first surface of the second gate. Each of the at least one layer of third field plate structures includes at least one third field plate.

[0168] Specifically, this application does not limit the number of metal field plate structures and the number of third field plate structures included in the bidirectional switch. The bidirectional switch may include N layers of metal field plate structures and M layers of third field plate structures, where N and M are both positive integers. Furthermore, each metal field plate structure and each third field plate structure may have different positional relationships. The following description uses a single third field plate structure and a single metal field plate structure as examples to illustrate different fabrication methods corresponding to different positional relationships.

[0169] Method 1:

[0170] If the i-th layer third field plate structure and the j-th layer metal field plate structure are set on the same layer (i is a positive integer less than or equal to M, j is a positive integer less than or equal to N), then the step S904 "forming at least one layer of metal field plate structure and at least one layer of third field plate structure on the barrier layer" can be implemented based on steps S904a-S904b.

[0171] S904a: A first metal layer is formed on the barrier layer.

[0172] The material of the first metal layer may include conductive materials such as Ti, Ta, TiN, and TaN, or aluminum, copper-doped silicon, and alloys containing the above materials.

[0173] Optionally, the material of the first metal layer may further include low-resistivity materials, such as polycrystalline silicon, silicon-chromium compounds, etc.

[0174] For example, the first metal layer can be deposited by a deposition process (such as electron beam evaporation or sputtering).

[0175] Optionally, a dielectric layer may be included between the barrier layer and the first metal layer, so that before step S904a, method 900 may further include: forming a dielectric layer on the barrier layer. Exemplarily, silicon oxides, silicon nitrides, or silicon oxynitrides can be deposited on the barrier layer using techniques such as chemical vapor deposition (CVD), atomic layer deposition (ALD), and plasma-enhanced chemical vapor deposition (PECVD).

[0176] S904b: Graphicalize the first metal layer to form the i-th layer third field plate structure and the j-th layer metal field plate structure.

[0177] It should be noted that for details regarding the third-field plate structure and the metal field plate structure, please refer to the preceding text. Figures 3-8 The relevant descriptions are not repeated here in the embodiments of this application. Furthermore, metal layer patterning includes locally processing or patterning the metal layer to achieve a patterned metal structure.

[0178] In this scenario, a single mask can be used to fabricate both a metal field plate and a third field plate on the same layer, effectively reducing the fabrication cost of the bidirectional switch. Furthermore, the same-layer structure can further compress space, allowing for higher integration density in the bidirectional switch.

[0179] Method 2:

[0180] If the third field plate structure of the p-th layer and the metal field plate structure of the q-th layer are set on different layers (p is a positive integer less than or equal to M, and q is a positive integer less than or equal to N), then the step S904 "forming at least one metal field plate structure and at least one third field plate structure on the barrier layer" can be implemented based on steps S904c-S904f.

[0181] S904c: A second metal layer is formed on the barrier layer.

[0182] S904d: Pattern the second metal layer to form the third field plate structure of the p-th layer.

[0183] S904e: A third metal layer is formed on the third field plate structure of the p-th layer.

[0184] S904f: Graphicalize the third metal layer to form the q-th metal field plate structure.

[0185] The materials of the second and / or third metal layers may include conductive materials such as Ti, Ta, TiN, and TaN, or aluminum, copper-doped silicon, and alloys comprising the above materials. Optionally, the materials of the second and / or third metal layers may further include low-resistivity materials, such as polycrystalline silicon and silicon-chromium compounds.

[0186] It should be understood that the difference between steps S904c-S904f and steps S904a-S904b lies in the fact that the third field plate structure and the metal field plate structure are set on different layers. Therefore, it is necessary to fabricate the metal field plate and the third field plate with different layers based on two masks. The specific fabrication process is similar to that of steps S904a-S904b, in which a metal layer is deposited through a deposition process, and the metal layer is patterned to form the third field plate or the metal field plate, which will not be elaborated here.

[0187] Furthermore, the embodiments of this application do not limit the third field plate structure and the metal field plate structure, nor their formation order. In one possible implementation, the q-th layer metal field plate structure may be formed on the barrier layer first, and then the p-th layer third field plate structure may be formed on the q-th layer metal field plate structure.

[0188] It should be noted that the embodiments of this application are not limited to using only one of the above-mentioned methods one and two in the process of fabricating the bidirectional switch (that is, it is not limited to the bidirectional switch only including the metal field plate structure and the third field plate structure disposed on the same layer or different layers). The fabrication process of the bidirectional switch can also include both methods one and two at the same time (that is, methods one and two can be combined, so the bidirectional switch can include both the metal field plate structure and the third field plate structure disposed on the same layer, or it can include the metal field plate structure and the third field plate structure disposed on different layers).

[0189] It should also be noted that the fabrication process can be understood as sequentially covering the substrate surface with different materials to form different layers and layer structures. Therefore, if the lower layer structure does not cover the entire substrate surface, the upper layer structure may have corresponding "undulations," for example, the upper layer structure may appear as a "stepped" structure. The different layers in the embodiments of this application are used to indicate different layer structures formed during the fabrication process, and do not limit the "same layer" to necessarily being located on the same plane.

[0190] To facilitate understanding of the above embodiments provided in this application, the following points are made.

[0191] (1) In the various embodiments of this application, unless otherwise specified or logically conflicting, the terms and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0192] (2) In this application, "first" and "second" are used for descriptive convenience only to distinguish objects and are not intended to limit the scope of the embodiments of this application. They are not used to describe the order or sequence of features. It should be understood that the objects described in this way can be interchanged where appropriate so as to describe solutions other than those in the embodiments of this application.

[0193] (3) In this application, the words “exemplary,” “for example,” “exemplary,” “as another example,” etc., are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as an “exemplary” in this application should not be construed as being more preferred or advantageous than other embodiments or designs.

[0194] (4) In this application, “comprising,” “including,” “having,” and variations thereof mean “including but not limited to,” unless otherwise specifically emphasized. “At least one” means one or more, and “more” means two or more.

[0195] (5) In this application, "and / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, and c can mean: a, or, b, or, c, or, a and b, or, a and c, or, b and c, or, a, b, and c. Where a, b, and c can be single or multiple.

[0196] (6) Some optional features in the various embodiments of this application may not depend on other features in some scenarios, or may be combined with other features in some scenarios, without limitation.

[0197] (7) In this application, spatial descriptions, such as "above," "under," "upward," "left," "right," "below," "top," "bottom," "vertical," "horizontal," "one side," "above," "below," etc., are defined for a specific plane of a component or a group of components, and the orientation of the component can be shown in its corresponding figure. It should be understood that the spatial descriptions used herein are for illustrative purposes only, and the structure described herein can be arranged in space in any orientation or manner in practice, provided that the advantages of the embodiments of this application are not deviated from by such arrangement.

[0198] Furthermore, it should be noted that the actual shapes of various structures depicted as approximately rectangular may, in actual devices, be curved, have rounded edges, or have uneven thicknesses, due to manufacturing conditions. In this application, the use of straight lines and right angles is solely for the convenience of representing layers and technical features.

[0199] Those skilled in the art will understand that various changes can be made and equivalent solutions can be substituted without departing from the spirit and scope of this application. Furthermore, numerous modifications can be made to adapt specific circumstances, materials, material compositions, processes, or one or more process steps to the purpose, spirit, and scope of this application. All such modifications are intended to be within the scope of the appended claims.

[0200] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing specific embodiments only and is not intended to limit the scope of this application. It should be understood that the above are illustrative examples, and the examples above are merely to help those skilled in the art understand the embodiments of this application, and are not intended to limit the embodiments of the application to the specific numerical values ​​or specific scenarios exemplified. Those skilled in the art can obviously make various equivalent modifications or variations based on the examples given above, and such modifications and variations also fall within the scope of the embodiments of this application.

[0201] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A bidirectional switch, characterized in that, include: A substrate, an active layer disposed on the substrate, and a barrier layer disposed on the active layer; A first gate, a second gate, a first source, and a second source are disposed on the first surface of the barrier layer, wherein the first gate is disposed between the first source and the second gate, and the second gate is disposed between the first gate and the second source; At least one layer of metal field plate structure, each layer of the at least one layer of metal field plate structure includes a first field plate and a second field plate, one end of the first field plate is electrically connected to the first source electrode, and one end of the second field plate is electrically connected to the second source electrode; At least one third field plate structure is provided, wherein the at least one third field plate structure is disposed above a first plane, and the projection of the at least one third field plate structure onto the first plane is located between the first gate and the second gate, wherein the first plane is the plane containing the first surface of the first gate and the first surface of the second gate, and each third field plate structure in the at least one third field plate structure includes at least one third field plate.

2. The bidirectional switch according to claim 1, characterized in that, The bidirectional switch includes an N-layer metal field plate structure and an N-layer third field plate structure, wherein the i-th third field plate structure and the i-th metal field plate structure are disposed on the same layer, where N is a positive integer and i is a positive integer less than or equal to N.

3. The bidirectional switch according to claim 1, characterized in that, The bidirectional switch includes an N-layer metal field plate structure and an M-layer third field plate structure. The i-th third field plate structure and the j-th metal field plate structure are located on the same layer. N and M are both positive integers, i is a positive integer less than or equal to M, j is a positive integer less than or equal to N, and M is less than or equal to N.

4. The bidirectional switch according to any one of claims 1 to 3, characterized in that, Each layer of the third field plate structure includes at least one third field plate in a first direction and at least one third field plate in a second direction.

5. The bidirectional switch according to claim 4, characterized in that, In the case where each layer of the third field plate structure includes a third field plate in the first direction, the third field plate is a strip-shaped field plate extending along the first direction.

6. The bidirectional switch according to any one of claims 1 to 5, characterized in that, In the case where the bidirectional switch includes a multi-layer third field plate structure, the projections of the third field plates of at least two of the multi-layer third field plate structures onto the first plane at least partially overlap. Alternatively, the projections of the third field plates in the multilayer third field plate structure onto the first plane do not overlap.

7. The bidirectional switch according to any one of claims 1 to 6, characterized in that, The projection shape of the third field plate onto the first plane includes rectangles, squares, circles, ellipses, spindles, and / or polygons.

8. The bidirectional switch according to any one of claims 1 to 7, characterized in that, The bidirectional switch also includes: A dielectric layer is disposed between the barrier layer and the at least one field plate structure, the dielectric layer encapsulates the at least one third field plate structure, and the material of the dielectric layer includes silicon oxide, silicon nitride, or silicon oxynitride.

9. The bidirectional switch according to any one of claims 1 to 8, characterized in that, The bidirectional switch is a nitrogen-based bidirectional switch, the active layer is a nitrogen-based active layer, and the barrier layer is a nitrogen-based barrier layer.

10. The bidirectional switch according to any one of claims 2 to 9, characterized in that, The metal field plate structure and the third field plate structure, which are located on the same layer, are formed by etching the same layer of material.

11. A method for preparing a bidirectional switch, characterized in that, include: An active layer is formed on the substrate; A barrier layer is formed on the active layer; A first gate, a second gate, a first source, and a second source are formed on the first surface of the barrier layer. The first gate is disposed between the first source and the second gate, and the second gate is disposed between the first gate and the second source. At least one metal field plate structure and at least one third field plate structure are formed on the barrier layer. Each metal field plate structure in the at least one metal field plate structure includes a first field plate and a second field plate. One end of the first field plate is electrically connected to the first source electrode, and one end of the second field plate is electrically connected to the second source electrode. The at least one third field plate structure is disposed above a first plane, and its projection on the first plane is located between the first gate electrode and the second gate electrode. The first plane is the plane containing the first surface of the first gate electrode and the first surface of the second gate electrode. Each third field plate structure in the at least one third field plate structure includes at least one third field plate.

12. The method according to claim 11, characterized in that, The bidirectional switch includes an N-layer metal field plate structure and an M-layer third field plate structure. If the i-th third field plate structure and the j-th metal field plate structure are disposed on the same layer, N and M are both positive integers, i is a positive integer less than or equal to M, and j is a positive integer less than or equal to N. The formation of at least one metal field plate structure and at least one third field plate structure on the barrier layer includes: A first metal layer is formed on the barrier layer; The first metal layer is graphically represented to form the i-th layer third field plate structure and the j-th layer metal field plate structure.

13. The method according to claim 11 or 12, characterized in that, The bidirectional switch includes an N-layer metal field plate structure and an M-layer third field plate structure. If the p-th third field plate structure and the q-th metal field plate structure are located on different layers, N and M are both positive integers, p is a positive integer less than or equal to M, and q is a positive integer less than or equal to N. The formation of at least one metal field plate structure and at least one third field plate structure on the barrier layer includes: A second metal layer is formed on the barrier layer; The second metal layer is graphically represented to form the p-th layer third field plate structure; A third metal layer is formed on the p-th third field plate structure; The third metal layer is graphically represented to form the q-th metal field plate structure.

14. An electronic device, characterized in that, It includes a drive circuit, a filter circuit, a control circuit, a power conversion circuit, and at least one bidirectional switch as described in any one of claims 1 to 10.

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