Semiconductor structure and preparation method of semiconductor structure

Abstract

The invention provides a semiconductor structure and a preparation method of the semiconductor structure. The semiconductor structure comprises a substrate, a channel layer and a barrier layer, wherein the channel layer and the barrier layer are sequentially stacked on the substrate; the cap layer is located on a part of the barrier layer; the passivation layer is located on the cap layer and the barrier layer; the gate electrode penetrates through the passivation layer above the cap layer until the gate electrode is in contact with the cap layer; the source electrode is located on one side of the cap layer and penetrates through the passivation layer to be in contact with the barrier layer; the drain electrode is located on the other side of the cap layer and penetrates through the passivation layer to be in contact with the barrier layer; the phase change field plate is positioned on the passivation layer between the cap layer and the drain electrode and is used for changing an electric field around the cap layer; wherein when the temperature is less than or equal to the preset temperature, the material attribute of the phase change field plate is an insulating material, and when the temperature is greater than the preset temperature, the material attribute of the phase change field plate is a metal material, so that the self-heating effect of the HEMT device is relieved, and meanwhile, the frequency attenuation of the device caused by the self-heating effect is relieved; and the frequency characteristic of the device is maintained to a great extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor, in particular to a semiconductor structure and a preparation method of the semiconductor structure. BACKGROUND

[0002] Silicon-based gallium nitride high electron mobility transistor (HEMT) gradually becomes a new star technology scheme of power devices in the industry due to the advantages of high breakdown field strength, high electron mobility, silicon process compatibility, etc. It is found through research that the HEMT device working under high power for a long time has a serious self-heating effect, which causes the channel temperature to rise, reduces the carrier mobility, and seriously affects the power, radio frequency and other performances of the device.

[0003] At present, the industry mainly introduces a metal field plate structure in the device area to adjust the distribution of the gate channel electric field, avoid the concentration of the electric field near the gate, and reduce the device temperature. However, the metal field plate increases the parasitic capacitance of the device, and the frequency characteristics of the device will decrease due to the introduction of the metal field plate, thereby increasing the switching power consumption. Therefore, it is urgent to provide a method capable of reducing the self-heating effect of the HEMT device while avoiding affecting the frequency characteristics of the device.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely describing the technical scheme of the present application and facilitating the understanding of those skilled in the art. The above technical scheme cannot be considered as known to those skilled in the art merely because it is described in the background section of the present application. SUMMARY

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a semiconductor structure and a preparation method of the semiconductor structure, thereby reducing the self-heating effect of the HEMT device while avoiding affecting the frequency characteristics of the device.

[0006] To achieve the above-mentioned purpose and other related purposes, the present application provides a semiconductor structure, comprising: a substrate, the substrate comprising a substrate and a channel layer and a barrier layer which are sequentially stacked on the substrate; a cap layer located on part of the barrier layer; a passivation layer located on the cap layer and the barrier layer; a gate electrode penetrating the passivation layer located above the cap layer until contacting the cap layer; a source electrode located on one side of the cap layer, the source electrode penetrating the passivation layer and contacting the barrier layer; a drain electrode located on the other side of the cap layer, the drain electrode penetrating the passivation layer and contacting the barrier layer; a phase-change field plate on the passivation layer between the cap layer and the drain electrode, for changing the electric field distribution around the cap layer; wherein, in the case of temperature less than or equal to a preset temperature, the material property of the phase-change field plate is insulating material, in the case of temperature greater than the preset temperature, the material property of the phase-change field plate is metallic material.

[0007] In one of the embodiments, the material of the phase-change field plate comprises vanadium dioxide.

[0008] In one of the embodiments, the semiconductor structure further comprises a connecting structure on the gate electrode, the cap layer, the phase-change field plate, for connecting the phase-change field plate and the gate electrode.

[0009] In one of the embodiments, the semiconductor structure further comprises a connecting structure for connecting the phase-change field plate and the source electrode.

[0010] In one of the embodiments, the distance between the drain electrode and the gate electrode is a first distance; the width of the phase-change field plate is greater than or equal to one fifth of the first distance, and the width of the phase-change field plate is less than or equal to one half of the first distance.

[0011] In one of the embodiments, the thickness of the phase-change field plate is 50-200 nanometers.

[0012] In a second aspect, the application provides a preparation method of a semiconductor structure, comprising: providing a substrate, the substrate comprising a substrate and a channel layer and a barrier layer stacked on the substrate in sequence; forming a cap layer on part of the barrier layer; forming a passivation layer on the cap layer and the barrier layer; forming a phase-change field plate on part of the passivation layer; wherein, the phase-change field plate is for changing the electric field distribution around the cap layer; in the case of temperature less than or equal to a preset temperature, the material property of the phase-change field plate is insulating material, in the case of temperature greater than the preset temperature, the material property of the phase-change field plate is metallic material; forming a gate electrode, a source electrode and a drain electrode; wherein, the gate electrode penetrates the passivation layer above the cap layer, until contacting the cap layer; the source electrode is on one side of the cap layer, the source electrode penetrates the passivation layer and contacts the barrier layer; the drain electrode is on the other side of the cap layer, the drain electrode penetrates the passivation layer and contacts the barrier layer; the phase-change field plate is on the passivation layer between the gate electrode and the drain electrode.

[0013] In one of the embodiments, the forming of the phase-change field plate on part of the passivation layer comprises: forming a phase change material layer on the passivation layer; etching the phase change material layer to reserve the phase change material layer on the passivation layer at a preset position; annealing the phase change material layer to form the phase change field plate.

[0014] In one of the embodiments, the annealing the phase change material layer comprises: annealing the phase change material layer at a preset temperature, the preset temperature being 500-700 degrees Celsius.

[0015] In one of the embodiments, the distance between the drain electrode and the gate electrode is a first distance; the width of the phase change field plate is greater than or equal to one fifth of the first distance, and the width of the phase change field plate is less than or equal to one half of the first distance; the thickness of the phase change field plate is 50-200 nanometers.

[0016] As described above, the semiconductor structure and the preparation method of the semiconductor structure have the following beneficial effects: The semiconductor structure and the preparation method of the semiconductor structure comprise a substrate, a cap layer, a passivation layer, a gate electrode, a source electrode, a drain electrode and a phase change field plate; the substrate comprises a substrate, a channel layer and a barrier layer which are sequentially stacked on the substrate; the cap layer is located on part of the barrier layer; the passivation layer is located on the cap layer and the barrier layer; the gate electrode penetrates through the passivation layer above the cap layer and contacts the cap layer; the source electrode is located on one side of the cap layer and penetrates through the passivation layer to contact the barrier layer; the drain electrode is located on the other side of the cap layer and penetrates through the passivation layer to contact the barrier layer; the phase change field plate is located on the passivation layer between the cap layer and the drain electrode and is used to change the electric field around the cap layer; when the temperature is less than or equal to a preset temperature, the material property of the phase change field plate is an insulating material, and when the temperature is greater than the preset temperature, the material property of the phase change field plate is a metallic material. In this application, the material that can change phase is used as the phase change field plate. When the temperature of the HEMT device does not exceed the preset temperature, the phase change field plate is an insulating material, which reduces the parasitic capacitance compared with the metallic field plate. When the self-heating effect of the device occurs, the temperature of the device exceeds the preset temperature, the phase change field plate is a metallic material, which can widen the electric field and relieve the self-heating effect of the device, thereby reducing the self-heating effect of the HEMT device while greatly maintaining the frequency characteristics of the device. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application, constitute a part of the specification and illustrate the embodiments of the application together with the text of the specification. Obviously, the accompanying drawings described below are only some of the embodiments of the application.

[0018] Figure 1 A schematic diagram of a semiconductor structure according to an embodiment of the present application; Figure 2 A schematic diagram of a semiconductor structure according to another embodiment of the present application; Figure 3 A schematic diagram of a semiconductor structure according to yet another embodiment of the present application; Figure 4 A flowchart of a method of fabricating a semiconductor structure according to an embodiment of the present application; Figures 5-8 A schematic diagram of a structure resulting from a method of fabricating a semiconductor structure according to an embodiment of the present application; Figure 9 A flowchart of a method of fabricating a semiconductor structure according to another embodiment of the present application. DETAILED DESCRIPTION

[0019] The forgoing detailed description of the application has been presented for the purposes of elucidation and will not limit the application as construed. It is intended that the description of the application serve as an exemplification only and that various other embodiments, modifications, and equivalents thereof will become apparent to those skilled in the art in view of the detailed description.

[0020] It should be emphasized that the term comprises / comprising, when used in this specification, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0021] Features described and / or illustrated with respect to one implementation can be used in the same or similar manner in one or more other implementations, in combination with or in place of features in other implementations, or in place of or in addition to features described or illustrated with respect to another implementation.

[0022] As in the detailed description of the embodiments of the present application, for the convenience of explanation, the sectional views showing the device structures will be partially enlarged without the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application herein. In addition, three-dimensional spatial dimensions of length, width and depth should be included in actual fabrication.

[0023] For convenience of description, spatial relationship words such as "under", "below", "lower", "underneath", "above", "upper" and the like can be used herein to describe the relationship of one element or feature to another element or feature as shown in the drawings. It will be understood that these spatial relationship words are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or one or more intervening layers can also be present.

[0024] In the context of the present application, a structure described as having a first feature "on" a second feature can include embodiments in which the first and second features are formed in direct contact, and can also include embodiments in which additional features are formed between the first and second features such that the first and second features can not be in direct contact.

[0025] It should be noted that the diagrams in the embodiments provided in the present application only schematically illustrate the basic concepts of the present application, and only show the components related to the present application in the diagrams, rather than being drawn according to the number, shape and size of the components in actual implementation. The shapes, number and proportions of the components in actual implementation can be arbitrarily changed, and the layout pattern of the components can be more complex.

[0026] As mentioned in the background, in the working state, the electric field is too concentrated at the edge of the gate of the device, which leads to excessive energy of the carrier, concentrated heat production, and finally leads to a sharp rise in heat near the gate of the device, which causes the temperature of the channel to rise, the mobility of the carrier to decrease, and the performance of the device to be seriously affected, which is called "self-heating effect". Therefore, a metal field plate structure is often introduced in the device region to adjust the distribution of the gate-channel electric field, avoid the concentration of electric field near the gate, and reduce the temperature of the device to alleviate the self-heating effect. However, the metal field plate increases the parasitic capacitance of the device, and the frequency characteristics of the device will decrease due to the parasitic capacitance introduced by the metal field plate, and the switching power consumption will increase.

[0027] Based on the above reasons, please refer to Figure 1The application provides a semiconductor structure, comprising: a substrate, a cap layer 105, a passivation layer 104, a gate electrode 108, a source electrode 106, a drain electrode 107 and a phase-change field plate 109; wherein the substrate comprises a substrate 101 and a channel layer 102 and a barrier layer 103 which are sequentially stacked on the substrate 101; the cap layer 105 is located on part of the barrier layer 103; the passivation layer 104 is located on the cap layer 105 and the barrier layer 103; the gate electrode 108 penetrates the passivation layer 104 above the cap layer 105 and is in contact with the cap layer 105; the source electrode 106 is located on one side of the cap layer 105 and penetrates the passivation layer 104 and is in contact with the barrier layer 103; the drain electrode 107 is located on the other side of the cap layer 105 and penetrates the passivation layer 104 and is in contact with the barrier layer 103; the phase-change field plate 109 is located on the passivation layer 104 between the cap layer 105 and the drain electrode 107 and is used for changing the electric field distribution around the cap layer 105; wherein the material property of the phase-change field plate 109 is an insulating material when the temperature is less than or equal to a preset temperature, and the material property of the phase-change field plate 109 is a metallic material when the temperature is greater than the preset temperature.

[0028] For example, the material of the substrate 101 can comprise a semiconductor material, an insulating material, a conductor material or any combination thereof. The substrate 101 can be a single-layer structure or a multi-layer structure. For example, the material of the substrate 101 can comprise a silicon (Si) substrate, a silicon germanium (SiGe) substrate, a silicon germanium carbon (SiGeC) substrate, a silicon carbide (SiC) substrate, a gallium arsenide (GaAs) substrate, an indium arsenide (InAs) substrate, an indium phosphide (InP) substrate or other III / V semiconductor substrate or II / VI semiconductor substrate. Alternatively, for example, the substrate 101 can be a layered substrate comprising, for example, Si / SiGe, Si / SiC, silicon-on-insulator (SOI) or silicon germanium-on-insulator. Therefore, the type of the substrate 101 should not limit the protection scope of the present application.

[0029] For example, the material of the channel layer 102 can comprise AlN, GaN, InGaN, AlGaN, InN, etc., and the material of the barrier layer 103 can comprise AlGaN, InAlN, etc. The material of the cap layer 105 can comprise P-type GaN, P-type Al x Ga 1-x N(0≤x≤1), etc. The material of the passivation layer 104 can comprise SiN, SiO, SiON, AlN, Al2O3, etc. The material of the gate electrode 108, the source electrode 106 and the drain electrode 107 can comprise one or more combinations of nickel, platinum, gold, titanium, tungsten and other metal materials.

[0030] For example, the preset temperature is associated with the material of the phase-change field plate 109. The application does not specifically limit the value of the preset temperature.

[0031] In the above embodiment, by making the semiconductor structure include: a substrate, a cap layer, a passivation layer, a gate electrode, a source electrode, a drain electrode, and a phase-change field plate; wherein the substrate includes a substrate and a channel layer and a barrier layer which are sequentially stacked on the substrate; the cap layer is located on part of the barrier layer; the passivation layer is located on the cap layer and the barrier layer; the gate electrode penetrates the passivation layer above the cap layer and contacts the cap layer; the source electrode is located on one side of the cap layer, and the source electrode penetrates the passivation layer and contacts the barrier layer; the drain electrode is located on the other side of the cap layer, and the drain electrode penetrates the passivation layer and contacts the barrier layer; the phase-change field plate is located on the passivation layer between the cap layer and the drain electrode, and is used to change the electric field around the cap layer; wherein in the case that the temperature is less than or equal to a preset temperature, the material property of the phase-change field plate is an insulating material, and in the case that the temperature is greater than the preset temperature, the material property of the phase-change field plate is a metallic material. The application uses a material that can change phase as a phase-change field plate. When the temperature of the HEMT device does not exceed the preset temperature, the phase-change field plate is an insulating material, which reduces the parasitic capacitance compared to a metallic field plate. When the device has a self-heating effect, causing the temperature of the device to exceed the preset temperature, the phase-change field plate is a metallic material, which can widen the electric field and alleviate the self-heating effect of the device, thereby reducing the self-heating effect of the HEMT device while avoiding affecting the frequency characteristics of the device.

[0032] In some embodiments, the material of the phase-change field plate includes vanadium dioxide.

[0033] In the above embodiment, the preset temperature of vanadium dioxide can be 68 degrees Celsius. In the case that the temperature is less than or equal to 68 degrees Celsius, the resistivity of vanadium dioxide is large, and the material property is an insulating material. In the case that the temperature is greater than 68 degrees Celsius, the resistivity of vanadium dioxide decreases sharply, and the material property is a metallic material. In addition, the currently studied HEMT high thermal conductivity material mainly conducts heat through phonons, while vanadium dioxide conducts heat through electrons, and its conduction efficiency is higher than that of phonons, which can more efficiently conduct heat.

[0034] In some embodiments, please continue to refer to Figure 1 The distance between the drain electrode and the gate electrode is a first distance W; the width of the phase-change field plate is greater than or equal to one-fifth of the first distance W, and the width of the phase-change field plate is less than or equal to one-half of the first distance W.

[0035] As an example, the width of the phase-change field plate can include one-fifth of the first distance W, one-fourth of the first distance W, one-third of the first distance W, one-half of the first distance W, etc.

[0036] In the above embodiments, the width of the phase-change field plate determines the influence ability of the phase-change field plate on the electric field. If the width of the phase-change field plate is too small, the influence on the electric field is weak, and the device temperature cannot be reduced well. If the width of the phase-change field plate is too wide, the distance between the phase-change field plate and the drain electrode is too close, breakdown is prone to occur, and the parasitic capacitance is also increased.

[0037] In some embodiments, the thickness of the phase-change field plate is 50-200 nm.

[0038] For example, the thickness of the phase-change field plate is 50 nm, 90 nm, 100 nm, 150 nm, 200 nm, etc.

[0039] In some embodiments, referring to Figure 2 The semiconductor structure further includes a connection structure 110 on the gate electrode, the cap layer, and the phase-change field plate, for connecting the phase-change field plate 109 and the gate electrode 108.

[0040] For example, the material of the connection structure 110 can include one or more combinations of nickel, platinum, gold, titanium, tungsten, etc.

[0041] In some embodiments, referring to Figure 3 The semiconductor structure further includes a connection structure 110 for connecting the phase-change field plate 109 and the source electrode 106.

[0042] For example, the material of the connection structure 110 can include one or more combinations of nickel, platinum, gold, titanium, tungsten, etc. In addition, the connection structure 110 is connected with the phase-change field plate 109 and the source electrode 106, and spans above the gate electrode 108 without contacting the gate electrode 108, thereby forming the phase-change field plate 109 connected with the source electrode 106.

[0043] In some embodiments, referring to Figure 1 The phase-change field plate 109 can include a floating phase-change field plate 109.

[0044] In some embodiments, the thickness of the barrier layer is 10-20 nm.

[0045] For example, the thickness of the barrier layer is 10 nm, 12 nm, 14 nm, 15 nm, 16 nm, 18 nm, 20 nm, etc.

[0046] In some embodiments, the thickness of the cap layer is 50-200 nm.

[0047] For example, the thickness of the cap layer is 50 nm, 80 nm, 100 nm, 140 nm, 180 nm, 200 nm, etc.

[0048] In some embodiments, the thickness of the passivation layer is 20-80 nm. For example, the thickness of the passivation layer is 20 nm, 40 nm, 50 nm, 60 nm, 80 nm, etc.

[0049] In some embodiments, a buffer layer is further included between the substrate and the channel layer, and the material of the buffer layer includes gallium nitride.

[0050] In some embodiments, referring to Figure 4 , Figures 5-8 and Figure 1 , the application further provides a method for preparing a semiconductor structure, including steps S802-S810.

[0051] Step S802: providing a substrate, the substrate including a substrate 101, a channel layer 102 and a barrier layer 103 stacked on the substrate 101 in sequence.

[0052] Step S804: forming a cap layer 105 on part of the barrier layer 103.

[0053] Step S806: forming a passivation layer 104 on the cap layer 105 and the barrier layer 103.

[0054] Step S808: forming a phase-change field plate 109 on part of the passivation layer 104; the phase-change field plate 109 is used to change the electric field distribution around the cap layer 105; when the temperature is less than or equal to a preset temperature, the material property of the phase-change field plate 109 is an insulating material, and when the temperature is greater than the preset temperature, the material property of the phase-change field plate 109 is a metallic material.

[0055] Step S810: forming a gate electrode 108, a source electrode 106 and a drain electrode 107; the gate electrode 108 penetrates through the passivation layer 104 above the cap layer 105 and contacts the cap layer 105; the source electrode 106 is located on one side of the cap layer 105 and penetrates through the passivation layer 104 to contact the barrier layer 103; the drain electrode 107 is located on the other side of the cap layer 105 and penetrates through the passivation layer 104 to contact the barrier layer 103; the phase-change field plate 109 is located on the passivation layer 104 between the gate electrode 108 and the drain electrode 107.

[0056] As an example, the forming the gate electrode 108, the source electrode 106, and the drain electrode 107 in step S810 can include: etching the passivation layer 104 by using photolithography to form a first window (not shown), a second window (not shown), and a third window (not shown) exposing the cap layer 105 and part of the barrier layer 103; wherein the first window, the second window, and the third window are located corresponding to the positions of the gate electrode 108, the source electrode 106, and the drain electrode 107; and depositing a metal material on the passivation layer 104, the metal material at least filling the first window, the second window, and the third window to form the gate electrode 108, the source electrode 106, and the drain electrode 107.

[0057] In some embodiments, referring to Figure 9 , the forming the phase-change field plate on part of the passivation layer in step S808 can include: steps S1302-S1306.

[0058] In step S1302, a phase-change material layer (not shown) is formed on the passivation layer 104.

[0059] As an example, the forming the phase-change material layer on the passivation layer 104 in step S1302 can include: forming the phase-change material layer by using deposition processes such as high-temperature direct-current reactive sputtering, pulsed laser deposition, metal thermal oxidation, atomic layer deposition, etc.

[0060] In step S1304, the phase-change material layer is etched to reserve the phase-change material layer on the passivation layer at a preset position.

[0061] As an example, the preset position can be designed according to actual requirements. In the embodiments of the present application, the preset position can include between the gate electrode and the drain electrode.

[0062] In step S1306, the phase-change material layer is annealed to form the phase-change field plate.

[0063] In the above embodiments, the deposited phase-change material layer needs to be annealed and recrystallized to improve its crystal structure, so that the material properties are optimized and close to the required values.

[0064] In some embodiments, the annealing the phase-change material layer in step S1306 can include: annealing the phase-change material layer at a preset temperature, the preset temperature being 500-700 degrees Celsius.

[0065] As an example, the phase-change material layer can be treated at a preset temperature in oxygen or air. The preset temperature can include 500 degrees Celsius, 550 degrees Celsius, 600 degrees Celsius, 630 degrees Celsius, 650 degrees Celsius, 700 degrees Celsius, etc. In addition, the annealing time can include 2-6 hours, such as 2 hours, 4 hours, 6 hours, etc.

[0066] In some embodiments, the distance between the drain electrode and the gate electrode is a first distance; the width of the phase-change field plate is greater than or equal to one-fifth of the first distance, and less than or equal to one-half of the first distance; and the thickness of the phase-change field plate is 50-200 nm.

[0067] In some embodiments, the material of the phase-change field plate comprises vanadium dioxide.

[0068] In some embodiments, the method for preparing the semiconductor structure further comprises a step of forming a connecting structure; wherein the connecting structure is located on the gate electrode, the cap layer, and the phase-change field plate, and is used to connect the phase-change field plate and the gate electrode.

[0069] In some embodiments, the method for preparing the semiconductor structure further comprises a step of forming a connecting structure; wherein the connecting structure is used to connect the phase-change field plate and the source electrode.

[0070] In summary, the semiconductor structure and the method for preparing the semiconductor structure of the present application comprise: a substrate, a cap layer, a passivation layer, a gate electrode, a source electrode, a drain electrode, and a phase-change field plate; wherein the substrate comprises a substrate, a channel layer, and a barrier layer which are sequentially stacked on the substrate; the cap layer is located on part of the barrier layer; the passivation layer is located on the cap layer and the barrier layer; the gate electrode penetrates through the passivation layer above the cap layer until it contacts the cap layer; the source electrode is located on one side of the cap layer and penetrates through the passivation layer to contact the barrier layer; the drain electrode is located on the other side of the cap layer and penetrates through the passivation layer to contact the barrier layer; the phase-change field plate is located on the passivation layer between the cap layer and the drain electrode, and is used to change the electric field around the cap layer; wherein when the temperature is less than or equal to a preset temperature, the material property of the phase-change field plate is an insulating material, and when the temperature is greater than the preset temperature, the material property of the phase-change field plate is a metallic material. In the present application, the material that can change phase is used as the phase-change field plate. When the temperature of the HEMT device does not exceed the preset temperature, the phase-change field plate is an insulating material, which reduces the parasitic capacitance compared with the metallic field plate. When the device has a self-heating effect, causing the temperature of the device to exceed the preset temperature, the phase-change field plate is a metallic material, which can widen the electric field and relieve the self-heating effect of the device, thereby reducing the self-heating effect of the HEMT device while greatly maintaining the frequency characteristics of the device. Therefore, the present application effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0071] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed in the present application should be covered by the claims of the present application.

Claims

1. A semiconductor structure, characterized in that, include: A substrate, the substrate comprising a substrate and a channel layer and a barrier layer sequentially stacked on the substrate; A cap layer, located on a portion of the aforementioned barrier layer; A passivation layer is located on the cap layer and the barrier layer; The gate electrode penetrates the passivation layer above the cap layer until it contacts the cap layer; The source electrode is located on one side of the cap layer and penetrates the passivation layer to contact the barrier layer. A drain electrode is located on the other side of the cap layer, and the drain electrode penetrates the passivation layer and contacts the barrier layer. A phase change field plate is located on a passivation layer between the cap layer and the drain electrode, and is used to change the electric field distribution around the cap layer; wherein, when the temperature is less than or equal to a preset temperature, the material property of the phase change field plate is an insulating material, and when the temperature is greater than the preset temperature, the material property of the phase change field plate is a metallic material.

2. The semiconductor structure according to claim 1, characterized in that, The material of the phase change field plate includes vanadium dioxide.

3. The semiconductor structure according to claim 1, characterized in that, The semiconductor structure also includes a connection structure located on the gate electrode, the cap layer, and the phase transition plate, for connecting the phase transition plate and the gate electrode.

4. The semiconductor structure according to claim 1, characterized in that, The semiconductor structure also includes a connection structure for connecting the phase change field plate and the source electrode.

5. The semiconductor structure according to claim 1, characterized in that, The distance between the drain electrode and the gate electrode is a first distance; the width of the phase change field plate is greater than or equal to one-fifth of the first distance, and the width of the phase change field plate is less than or equal to one-half of the first distance.

6. The semiconductor structure according to claim 1, characterized in that, The thickness of the phase change field plate is 50 nanometers to 200 nanometers.

7. A method for fabricating a semiconductor structure, characterized in that, include: A substrate is provided, the substrate comprising a substrate and a channel layer and a barrier layer sequentially stacked on the substrate; A cap layer is formed on a portion of the aforementioned barrier layer; A passivation layer is formed on the cap layer and the barrier layer; A phase change field plate is formed on a portion of the passivation layer; wherein the phase change field plate is used to change the electric field distribution around the cap layer; when the temperature is less than or equal to a preset temperature, the material property of the phase change field plate is an insulating material, and when the temperature is greater than the preset temperature, the material property of the phase change field plate is a metallic material. A gate electrode, a source electrode, and a drain electrode are formed; wherein, the gate electrode penetrates the passivation layer above the cap layer until it contacts the cap layer; the source electrode is located on one side of the cap layer, and the source electrode penetrates the passivation layer and contacts the barrier layer; the drain electrode is located on the other side of the cap layer, and the drain electrode penetrates the passivation layer and contacts the barrier layer; the phase transition field plate is located on the passivation layer between the gate electrode and the drain electrode.

8. The method for preparing a semiconductor structure according to claim 7, characterized in that, The formation of a phase transition field plate on a portion of the passivation layer includes: A phase change material layer is formed on the passivation layer; The phase change material layer is etched, while retaining the phase change material layer on the passivation layer at a preset position; The phase change material layer is annealed to form the phase change field plate.

9. The method for preparing a semiconductor structure according to claim 8, characterized in that, The annealing treatment of the phase change material layer includes: The phase change material layer is annealed at a preset temperature, which is 500 degrees Celsius to 700 degrees Celsius.

10. The method for preparing a semiconductor structure according to claim 7, characterized in that, The distance between the drain electrode and the gate electrode is a first distance; the width of the phase change field plate is greater than or equal to one-fifth of the first distance, and the width of the phase change field plate is less than or equal to one-half of the first distance; The thickness of the phase change field plate is 50 nanometers to 200 nanometers.

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