Gallium nitride pressure sensor and its fabrication method

Abstract

The present invention discloses a gallium nitride pressure sensor and a method for preparing the same. The gallium nitride pressure sensor comprises: a first substrate, a second substrate, an epitaxial structure, a source electrode, a drain electrode, a gate electrode and a groove. The source electrode, the drain electrode and the gate electrode are located on a side of the epitaxial structure away from the second substrate. The source electrode and the drain electrode are located on two opposite sides of the gate electrode respectively. The number of the gate electrodes is a positive integer greater than or equal to 2. There is a channel region between the source electrode and the drain electrode. Therefore, the gallium nitride pressure sensor of the present invention has more than two gate electrodes. By applying a voltage on the gate electrode to adjust the channel width, the channel width is adjusted, and the detection range, accuracy and sensitivity of the gallium nitride pressure sensor can be adjusted and optimized for a second time, thereby expanding the process preparation window and the application range of the pressure sensor.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and in particular relates to a gallium nitride pressure sensor and a preparation method thereof. Background Art

[0002] Semiconductor pressure sensor is a semiconductor transducer that converts pressure signal into electrical signal. It is widely used in industrial, medical, automotive electronics and consumer applications. Traditional silicon-based piezoresistive pressure sensor uses diffused silicon resistor to form varistor, but the varistor drifts with temperature change. Silicon-based piezoresistive pressure sensor can generally only work below 120℃. Gallium nitride is a wide bandgap semiconductor material. The operating temperature of pressure sensor based on gallium nitride technology can reach 600℃, and it has broad application prospects in the field of high-temperature pressure detection. Due to the piezoelectric polarization and self-polarization effects, AlGaN / GaN heterostructure forms a high-concentration, high-electron-mobility two-dimensional electron gas (2DEG) on the surface of the GaN channel layer. It is very sensitive to external pressure changes and is suitable as a high-sensitivity pressure sensor.

[0003] However, the pressure detection range and sensitivity of existing GaN pressure sensors are designed based on the size and thickness of the chip suspension membrane. Once the pressure sensor is manufactured, the pressure detection range, accuracy and sensitivity are fixed and cannot be adjusted again. That is, in the prior art, there is a defect that the pressure detection range, accuracy and sensitivity of the pressure sensor cannot be adjusted again. For pressure sensors with high consistency requirements, the corresponding manufacturing process also has high consistency, a small process window and low yield.

[0004] Therefore, it is necessary to improve the existing gallium nitride pressure sensor. Summary of the invention

[0005] In order to improve the above technical problems, the present invention provides a gallium nitride pressure sensor, which includes: a first substrate; a second substrate, the second substrate is located on one side of the first substrate; an epitaxial structure, the epitaxial structure is located on a side of the second substrate away from the first substrate, the epitaxial structure includes a stacked GaN buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, and a GaN cap layer, and the GaN buffer layer is located on a surface of one side of the second substrate; a source, a drain and a gate, the source, the drain and the gate are located on a side of the epitaxial structure away from the second substrate, the source and the drain are respectively located on two opposite sides of the gate, the number of the gates is a positive integer greater than or equal to 2, and a channel region is provided between the source and the drain; a groove, the groove is located on the second substrate, and the orthographic projection of the channel region on the first substrate at least partially overlaps with the orthographic projection of the groove on the first substrate. Therefore, the GaN pressure sensor has more than two gates, and the channel width is regulated by applying voltage on the gate, thereby achieving the regulation of the channel width, and improving the problem that the performance of the pressure sensor cannot be adjusted and optimized for a second time after it is manufactured. The present invention can perform secondary adjustment and optimization on the detection range, accuracy, and sensitivity of the GaN pressure sensor, expand the process manufacturing window, and extend the application range of the pressure sensor.

[0006] According to an embodiment of the present invention, the second substrate includes a base layer, an insulating layer and a silicon layer which are stacked, and the base layer is located on a side close to the first substrate.

[0007] According to an embodiment of the present invention, the thickness of the base layer is 100-500 μm; the thickness of the insulating layer is 0.5-5.5 μm; and the thickness of the silicon layer is 0.5-100 μm. The thickness of the pressure sensitive film of the pressure sensor can be regulated by the thickness of the silicon layer, thereby adjusting the pressure detection range of the pressure sensor, and at the same time, the consistency of the manufacturing process of the gallium nitride pressure sensor can be improved.

[0008] According to an embodiment of the present invention, the groove is located on the base layer, and an opening of the groove is located on a side of the base layer away from the insulating layer.

[0009] According to an embodiment of the present invention, the depth of the groove is 100-500 μm.

[0010] According to an embodiment of the present invention, the thickness of the GaN buffer layer is 0.5-5 μm, the thickness of the GaN channel layer is 0.2-5 μm, the thickness of the AlN insertion layer is 0.5-3 nm, the thickness of the AlGaN barrier layer is 10-100 nm, and the thickness of the GaN cap layer is 1-10 nm.

[0011] According to an embodiment of the present invention, the material forming the source and the drain includes at least one of Ti, Al, Ni, and Au; the material forming the gate includes at least one of Ti, Cr, Ni, Pt, and Au.

[0012] According to an embodiment of the present invention, the epitaxial structure is an enhancement-mode HEMT structure or a depletion-mode HEMT structure.

[0013] The present invention also provides a method for preparing a gallium nitride pressure sensor, the method comprising: forming an epitaxial structure on one side of a second substrate, the epitaxial structure comprising a stacked GaN buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer and a GaN cap layer, the GaN buffer layer being located on the surface of one side of the second substrate; forming a source, a drain and a gate on a side of the epitaxial structure away from the second substrate, the source and the drain being respectively located on two opposite sides of the gate, the number of the gates being a positive integer greater than or equal to 2; a channel region being provided between the source and the drain; etching the side of the second substrate away from the epitaxial structure to form a groove; forming a first substrate on the side of the second substrate away from the epitaxial structure, wherein an orthographic projection of the channel region on the first substrate at least partially overlaps with an orthographic projection of the groove on the first substrate.

[0014] According to some embodiments of the present invention, the gallium nitride pressure sensor prepared by the method has all the features and advantages of the gallium nitride pressure sensor described above, which will not be repeated here. In general, the gallium nitride pressure sensor prepared by the method has more than two gates, and the channel width is regulated by applying a voltage on the gate, thereby regulating the output current between the source and the drain, which can expand the pressure detection range of the pressure sensor and improve the accuracy and sensitivity of the pressure sensor.

[0015] According to an embodiment of the present invention, the forming of the source, drain and gate includes: etching the epitaxial structure to form an etched mesa; depositing a first metal layer and a second metal layer on the etched mesa to form a source and a drain; and depositing a third metal layer on the etched mesa to form a gate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of a gallium nitride pressure sensor in one embodiment of the present invention;

[0017] Figure 2 In one embodiment of the present invention, the gate voltage V GS1 =V GS2 =0V, top view of GaN pressure sensor, where V GS1 and V GS2 Respectively represent the voltages applied to the two gates;

[0018] Figure 3 is along Figure 2 The cross-sectional view in the AA' direction;

[0019] Figure 4 In one embodiment of the present invention, the gate voltage V GS1 <V T and V GS2 <V T Top view of the GaN pressure sensor, where V T is the threshold voltage of HEMT;

[0020] Figure 5 is along Figure 4 The cross-sectional view in the AA' direction;

[0021] Figure 6 It is a schematic structural diagram of the second substrate in one embodiment of the present invention.

[0022] Figure 7 It is a schematic diagram of the structure of a gallium nitride pressure sensor with adjustable channel width having a Wheatstone bridge structure;

[0023] Figure 8 is a flow chart of a method for preparing a gallium nitride pressure sensor in one embodiment of the present invention;

[0024] Fig. 9 is a flow chart of a method for preparing a source electrode, a drain electrode and a gate electrode in one embodiment of the present invention;

[0025] Fig.10 It is a schematic diagram of a structure in which a source electrode and a drain electrode are formed on an etching table in one embodiment of the present invention.

[0026] Description of reference numerals:

[0027] 100-first substrate, 200-second substrate, 210-base layer, 220-insulating layer, 230-silicon layer, 211-groove, 300-epitaxial structure, 300a-etched table, 310-GaN buffer layer, 320-GaN channel layer, 330-AlN insertion layer, 340-AlGaN barrier layer, 350-GaN cap layer, 400-drain, 500-source, 600-gate, 700-channel region, 800-gate control region, 900-support film. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific technology or conditions are indicated in the embodiments, the technology or conditions described in the documents in this area or the product instructions are used. The reagents used are not indicated by the manufacturer, and are all conventional products that can be purchased from the market.

[0029] The pressure detection range and sensitivity of existing gallium nitride pressure sensors are designed based on the chip suspension membrane size and thickness. Once the pressure sensor is manufactured, the pressure detection range, accuracy and sensitivity are fixed and cannot be adjusted a second time.

[0030] In order to improve the above technical problems, the present invention provides a gallium nitride pressure sensor, referring to Figure 1 The gallium nitride pressure sensor includes: a first substrate 100, a second substrate 200, an epitaxial structure 300, a drain 400, a source 500, a gate 600 and a groove (not shown in the figure), the second substrate 200 is located on one side of the first substrate 100; the epitaxial structure 300 is located on the side of the second substrate 200 away from the first substrate 100, the epitaxial structure 300 includes a stacked GaN buffer layer 310, a GaN channel layer 320, an AlN insertion layer 330, an AlGaN barrier layer 340, a GaN cap layer 350, and a GaN The buffer layer 310 is located on the surface of one side of the second substrate 200; the source 500, the drain 400 and the gate 600 are located on the side of the epitaxial structure 300 away from the second substrate 200, the source 500 and the drain 400 are respectively located on the opposite sides of the gate 600, the number of the gates 600 is a positive integer greater than or equal to 2, and there is a channel region 700 between the source 500 and the drain 400; the groove is located on the second substrate 200, and the orthographic projection of the channel region on the first substrate 100 at least partially overlaps with the orthographic projection of the groove on the first substrate 100. Therefore, the high electron mobility transistor (HEMT) unit has more than two gates 600, and the channel width is controlled by applying a voltage on the gate 600. Specifically, applying a driving voltage on the gate 600 can control the carrier transport of the two-dimensional electron gas (2DEG) in the AlGaN / GaN heterostructure thereunder, and regulate the channel width between the source 500 and the drain 400, thereby regulating the output current between the source 500 and the drain 400, which can expand the pressure detection range of the pressure sensor and improve the accuracy and sensitivity of the pressure sensor.

[0031] The present invention can perform secondary adjustment and optimization on the pressure detection range, accuracy, sensitivity and other performance of the pressure sensor, solve the consistency problem caused by process errors in the process, expand the process preparation window, and also expand the application scope of the pressure sensor.

[0032] According to an embodiment of the present invention, when the gallium nitride pressure sensor has more than two gates 600 , each gate 600 can be regulated separately, and the voltages applied to different gates 600 can be equal or unequal.

[0033] When the number of gates is 2, V GS1 and V GS2 Respectively represent the voltages applied to the two gates 600. When the gate voltage V GS1 =V GS2 =0V, reference Figure 2 and Figure 3 Due to the spontaneous polarization and piezoelectric polarization effect of the AlGaN barrier layer 340 and the GaN channel layer 320 in the AlGaN / GaN heterostructure, a high-concentration, high-electron-mobility two-dimensional electron gas is formed on the upper surface of the GaN channel layer 320. GS =0 V, the two-dimensional electron gas is distributed on the entire upper surface of the GaN channel layer 320, and the channel width of the transistor is the designed value W1.

[0034] V T is the threshold voltage of HEMT. When the gate voltage V GS1 <V T , and V GS2 <V T When, refer to Figure 4 and Figure 5 The gate control region 800 is near the gate 600 and is controlled by the voltage of the gate 600. The two-dimensional electron gas just below and at the edge of the gate 600 is depleted, and the equivalent channel width between the source 500 and the drain 400 becomes W2.

[0035] If the two gates 600 are closer to each other or more than two gates 600 are used, the channel width can be adjusted from 0 to a maximum of W1.

[0036] When the number of the gates 600 is 2, the two gates 600 may be symmetrically distributed or asymmetrically distributed.

[0037] The change in the channel width of the transistor changes the stress distribution position of the transistor on the support film accordingly, thereby realizing secondary adjustment and optimization of sensitivity and accuracy. Among them, the support film 900 refers to the structure located above the groove 211, and the support film 900 includes a silicon layer 230 and an epitaxial structure 300, and the support film 900 is used to sense changes in pressure. When external pressure is applied to the gallium nitride pressure sensor, the piezoelectric polarization electric field changes, thereby changing the charge density of the two-dimensional electron gas, and the channel current also changes accordingly, but the channel saturation current under different gate 600 voltage control is different, resulting in different pressure detection ranges, thereby realizing secondary adjustment and optimization of the pressure detection range. In short, the gallium nitride pressure sensor with adjustable channel width proposed in the present invention can perform secondary adjustment and optimization on the pressure detection range, accuracy, sensitivity and other performances of the pressure sensor, solve the consistency problem caused by errors in the process, expand the process preparation window, and also expand the application range of the pressure sensor.

[0038] According to an embodiment of the present invention, referring to Figure 6 The second substrate 200 includes a base layer 210 , an insulating layer 220 and a silicon layer 230 which are stacked, and the base layer 210 is located on a side close to the first substrate 100 .

[0039] According to an embodiment of the present invention, the thickness of the base layer 210 is 100-500 μm, for example, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm. If the thickness of the base layer is too large, the cost will increase and the process complexity will also increase. If the thickness of the base layer is too small, there is a risk of cracking and it is not easy to operate.

[0040] The thickness of the insulating layer 220 is 0.5-5.5 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm. The insulating layer is a stop layer for the etching process. If the thickness of the insulating layer is too large, the process is not easy to implement and the cost is high. If the thickness of the insulating layer is too small, it is not easy to operate.

[0041] The thickness of the silicon layer 230 is 0.5-100 μm, for example, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm. The thickness of the silicon layer can be designed according to the pressure measurement range of the pressure sensor. The greater the thickness of the silicon layer, the greater the pressure measurement range. The smaller the thickness of the silicon layer, the higher the sensitivity of the pressure sensor.

[0042] The thickness of the pressure sensitive film of the pressure sensor can be adjusted by selecting the thickness of the silicon layer 230, thereby adjusting the pressure detection range of the pressure sensor and improving the consistency of the manufacturing process of the gallium nitride pressure sensor. Specifically, the pressure sensor can be designed for the pressure range by changing the thickness of the silicon layer before manufacturing, or it can be adjusted by the gate after manufacturing.

[0043] Figure 7 Schematic diagram of the structure of a Wheatstone bridge-type GaN pressure sensor with adjustable channel width, see Figure 7 The Wheatstone bridge can be selected as a full Wheatstone bridge or a half Wheatstone bridge to improve the accuracy and sensitivity of the sensor. By applying voltage control on the gate, the channel width of the transistor is regulated. The change in the channel width of the transistor correspondingly changes the stress distribution position of the transistor on the support film 900, thereby achieving secondary adjustment optimization of sensitivity and accuracy. Furthermore, in the Wheatstone bridge structure, the electrical signal of the diagonal bridge arm increases or decreases as the pressure increases.

[0044] According to an embodiment of the present invention, the groove 211 is located on the base layer 210, and the opening of the groove 211 is located on the side of the base layer 210 away from the insulating layer 220. Thus, a reference pressure can be set so that a pressure difference is formed between the upper and lower sides of the support film. When the external pressure changes, the pressure difference changes, thereby affecting the output characteristics of the transistor.

[0045] According to an embodiment of the present invention, the depth of the groove 211 is 100-500 μm, for example, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm. The groove depth can be designed to have different pressure ranges. If the depth of the groove is too large, the design value may deviate greatly due to the angle of the deep silicon etching process.

[0046] According to an embodiment of the present invention, after the second substrate 200 is bonded to the first substrate 100 , the groove 211 formed on the second substrate 200 may be used as a reference pressure chamber.

[0047] According to an embodiment of the present invention, the thickness of the GaN buffer layer 310 is 0.5-5 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm. The GaN buffer layer can reduce the stress matching problem between the gallium nitride layer and the silicon layer. If the thickness of the GaN buffer layer is too large, the stress of the buffer layer is large. If the thickness of the GaN buffer layer is too small, it may cause a large dislocation density in the epitaxial layer.

[0048] The thickness of the GaN channel layer 320 is 0.2-5 μm, for example, 0.2 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm. If the thickness of the GaN channel layer is too large, the stress distribution will be uneven. If the thickness of the GaN channel layer is too small, the two-dimensional electron gas cannot be formed or the concentration of the two-dimensional electron gas is low.

[0049] The thickness of the AlN insertion layer 330 is 0.5-3nm, for example, 0.5nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm. The main function of the AlN insertion layer is to form a high barrier and increase the concentration of the two-dimensional electron gas. If the thickness of the AlN insertion layer is too small, it is not easy to implement and cannot effectively increase the concentration of the two-dimensional electron gas. If the thickness of the AlN insertion layer is too large, it may introduce great stress, reduce the epitaxial quality of the AlGaN barrier layer, and cause a decrease in mobility.

[0050] The thickness of the AlGaN barrier layer 340 is 10-100 nm, for example, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm. If the thickness of the AlGaN barrier layer is too small, the two-dimensional electron gas cannot be formed or the density of the two-dimensional electron gas may be low; if the thickness of the AlGaN barrier layer is too large, the concentration of the two-dimensional electron gas reaches saturation, which may lead to a decrease in mobility.

[0051] The thickness of the GaN cap layer 350 is 1-10 nm, for example, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm. If the thickness of the GaN cap layer is too small, the carrier concentration may be reduced; if the thickness of the GaN cap layer is too large, the contact resistance may be increased and the mobility of the two-dimensional electron gas may be reduced.

[0052] According to an embodiment of the present invention, the material forming the source 500 and the drain 400 includes at least one of Ti, Al, Ni, and Au. It should be noted that the material forming the source 500 and the material forming the drain 400 can be the same or different, and those skilled in the art can select according to the use requirements.

[0053] The material forming the gate 600 includes at least one of Ti, Cr, Ni, Pt, and Au.

[0054] According to an embodiment of the present invention, the epitaxial structure 300 is an enhancement-mode HEMT structure or a depletion-mode HEMT structure. The enhancement-mode HEMT structure is a normally-off device with a threshold voltage greater than 0, while the depletion-mode HEMT structure is a normally-on device with a threshold voltage less than 0.

[0055] The present invention also provides a method for preparing a gallium nitride pressure sensor, referring to Figure 8 , the method comprising:

[0056] S100, forming an epitaxial structure 300 on one side of a second substrate 200;

[0057] The epitaxial structure 300 includes a stacked GaN buffer layer 310 , a GaN channel layer 320 , an AlN insertion layer 330 , an AlGaN barrier layer 340 and a GaN cap layer 350 . The GaN buffer layer 310 is located on the surface of one side of the second substrate 200 .

[0058] S200, forming a source 500, a drain 400 and a gate 600 on a side of the epitaxial structure 300 away from the second substrate 200;

[0059] The source 500 and the drain 400 are respectively located on two opposite sides of the gate 600 , and the number of the gates 600 is a positive integer greater than or equal to 2; there is a channel region between the source 500 and the drain 400 .

[0060] According to an embodiment of the present invention, referring to Fig. 9 , the forming of the source 500, the drain 400 and the gate 600 includes:

[0061] S210, etching the epitaxial structure 300 to form an etching table;

[0062] S220, depositing a first metal layer and a second metal layer on the etching table to form a source electrode 500 and a drain electrode 400;

[0063] According to an embodiment of the present invention, referring to Fig.10 , a first metal layer and a second metal layer are deposited on the etching mesa 300 a , and appropriate annealing conditions are selected for alloying to form a source 500 and a drain 400 .

[0064] It should be noted that the material of the first metal layer and the material of the second metal layer can be the same or different, and those skilled in the art can select according to the use requirements. Further, the material of the first metal layer and the material of the second metal layer are independently selected from at least one of Ti, Al, Ni, and Au.

[0065] S230 , depositing a third metal layer on the etching mesa to form a gate 600 .

[0066] According to an embodiment of the present invention, a third metal layer is deposited in the region between the source 500 and the drain 400 to prepare two or more gates 600 to form a structure with adjustable channel width.

[0067] Furthermore, the material of the third metal layer is selected from at least one of Ti, Cr, Ni, Pt and Au.

[0068] S300, etching the side of the second substrate 200 away from the epitaxial structure 300 to form a groove 211;

[0069] Furthermore, the groove 211 is located below the channel region 700 , that is, the groove 211 is located on a side of the channel region 700 close to the first substrate 100 .

[0070] S400 , forming a first substrate 100 on a side of the second substrate 200 away from the epitaxial structure 300 .

[0071] The orthographic projection of the channel region 700 on the first substrate 100 at least partially overlaps with the orthographic projection of the groove 211 on the first substrate 100 .

[0072] According to the embodiment of the present invention, after the second substrate 200 and the first substrate 100 are bonded, the groove 211 is located between the first substrate 100 and the second substrate 200, and the groove 211 can be used as a pressure reference chamber.

[0073] According to some embodiments of the present invention, the gallium nitride pressure sensor prepared by the method has all the features and advantages of the gallium nitride pressure sensor described above, which will not be described in detail here.

[0074] In the examples described below in this application, unless otherwise specified, the materials used can be purchased from the market or can be prepared by the methods described in this application.

[0075] Example 1

[0076] 1) Selecting a second substrate 200, wherein the thickness of the silicon layer 230 is 20 μm, the thickness of the insulating layer 220 is 1 μm, and the thickness of the base layer 210 is 350 μm, pre-treating the surface of the second substrate 200, and sequentially growing a 1 μm thick GaN buffer layer 310, a 2 μm thick GaN channel layer 320, a 2 nm thick AlN insertion layer 330, a 30 nm thick AlGaN barrier layer 340, and a 3 nm thick GaN cap layer 350 on the second substrate 200 to form an epitaxial structure 300;

[0077] 2) selectively etching the epitaxial structure 300 using an inductively coupled plasma (ICP) etching device to form an etching table;

[0078] 3) depositing a metal layer Ti / Al / Ni / Au on the etching table, selecting appropriate annealing conditions for alloying, and preparing a source electrode 500 and a drain electrode 400;

[0079] 4) Depositing metal layers Ni / Au on both sides between the source electrode 500 and the drain electrode 400 to prepare two gate electrodes 600 to form a structure with adjustable channel width;

[0080] 5) Selectively etching the base layer 210 of the second substrate 200 below the source-drain channel region 700 of the HEMT device through a deep silicon etching process to form a groove 211, with an etching depth of 350 μm;

[0081] 6) The first substrate 100 is bonded to the side of the second substrate 200 away from the epitaxial structure 300 , so that the groove 211 is located between the first substrate 100 and the second substrate 200 , and the groove 211 serves as a pressure reference chamber.

[0082] It should be noted that in this specification, the terms "first", "second", "third" and "fourth" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. In the description of this application, the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer" and the like are based on the directions or positional relationships shown in the drawings and are only for the convenience of describing this application rather than requiring that this application must be constructed and operated in a specific direction, and therefore cannot be understood as limiting this application.

[0083] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0084] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A gallium nitride pressure sensor, characterized in that: The gallium nitride pressure sensor comprises: a first substrate; a second substrate, the second substrate being located on one side of the first substrate; an epitaxial structure, the epitaxial structure being located on a side of the second substrate away from the first substrate, the epitaxial structure comprising a stacked GaN buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer, and a GaN cap layer, the GaN buffer layer being located on a surface of one side of the second substrate; A source, a drain and a gate, wherein the source, the drain and the gate are located on a side of the epitaxial structure away from the second substrate, the source and the drain are respectively located on two opposite sides of the gate, the number of the gates is a positive integer greater than or equal to 2, and a channel region is provided between the source and the drain; A groove is located on the second substrate, and an orthographic projection of the channel region on the first substrate at least partially overlaps with an orthographic projection of the groove on the first substrate.

2. The gallium nitride pressure sensor according to claim 1, characterized in that: The second substrate includes a base layer, an insulating layer and a silicon layer which are stacked, and the base layer is located on a side close to the first substrate.

3. The gallium nitride pressure sensor according to claim 2, characterized in that: The thickness of the base layer is 100-500 μm; The thickness of the insulating layer is 0.5-5.5 μm; The thickness of the silicon layer is 0.5-100 μm.

4. The gallium nitride pressure sensor according to claim 2, characterized in that: The groove is located on the base layer, and an opening of the groove is located on a side of the base layer away from the insulating layer.

5. The gallium nitride pressure sensor according to claim 4, characterized in that: The depth of the groove is 100-500 μm.

6. The gallium nitride pressure sensor according to claim 1, characterized in that: The thickness of the GaN buffer layer is 0.5-5 μm, the thickness of the GaN channel layer is 0.2-5 μm, the thickness of the AlN insertion layer is 0.5-3 nm, the thickness of the AlGaN barrier layer is 10-100 nm, and the thickness of the GaN cap layer is 1-10 nm.

7. The gallium nitride pressure sensor according to claim 1, characterized in that: The material forming the source electrode and the drain electrode includes at least one of Ti, Al, Ni, and Au; The material forming the gate includes at least one of Ti, Cr, Ni, Pt, and Au.

8. The gallium nitride pressure sensor according to claim 1, characterized in that: The epitaxial structure is an enhancement-mode HEMT structure or a depletion-mode HEMT structure.

9. A method for preparing a gallium nitride pressure sensor, characterized in that: The method comprises: forming an epitaxial structure on one side of the second substrate, the epitaxial structure comprising a stacked GaN buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer and a GaN cap layer, wherein the GaN buffer layer is located on a surface of one side of the second substrate; A source electrode, a drain electrode and a gate electrode are formed on a side of the epitaxial structure away from the second substrate, the source electrode and the drain electrode are respectively located on two opposite sides of the gate electrode, and the number of the gate electrodes is a positive integer greater than or equal to 2; and a channel region is provided between the source electrode and the drain electrode; Etching a side of the second substrate away from the epitaxial structure to form a groove; A first substrate is formed on a side of the second substrate away from the epitaxial structure, wherein an orthographic projection of the channel region on the first substrate at least partially overlaps with an orthographic projection of the groove on the first substrate.

10. The preparation method according to claim 9, characterized in that: The forming of the source, the drain and the gate comprises: Etching the epitaxial structure to form an etched mesa; Depositing a first metal layer and a second metal layer on the etching mesa to form a source electrode and a drain electrode; A third metal layer is deposited on the etching mesa to form a gate.

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