CN113686468B - Pressure-induced barrier variation type gallium nitride pressure sensor and preparation method thereof - Google Patents

Abstract

The invention discloses a pressure-induced potential barrier variable gallium nitride pressure sensor and a preparation method thereof. The pressure-induced barrier variable gallium nitride pressure sensor includes: a first substrate and an epitaxial structure, and the epitaxial structure includes a GaN buffer layer, a GaN channel layer, an AlN insertion layer, and an AlGaN barrier layer sequentially formed on the first substrate. layer, GaN cap layer; wherein, the AlGaN barrier layer has a first groove, and an ohmic contact layer is formed in the first groove, and the ohmic contact layer communicates with the two-dimensional electron gas at the interface of the AlN insertion layer and the GaN channel layer to form a lower electrode; an upper electrode formed on at least part of the upper surface of the GaN cap layer; and a passivation layer covering at least part of the upper surface of the epitaxial structure. The piezo-induced barrier variable gallium nitride pressure sensor can directly measure the change of the external pressure according to the potential difference between the upper electrode and the lower electrode without an external driving voltage, that is, it can realize the change of the external pressure without an external driving voltage. zero power detection.

Description

Pressure-induced Barrier Variation Gallium Nitride Pressure Sensor and Its Preparation Method

technical field

The invention relates to the technical field of semiconductors, in particular, the invention relates to a pressure-induced potential barrier change gallium nitride pressure sensor and a preparation method thereof.

Background technique

A pressure sensor is a transducer that converts pressure signals into electrical signals directly, and is widely used in many fields such as industry, aerospace, new energy, rail transit, and automotive electronics. Traditional silicon-based piezoresistive pressure sensors use a diffusion process to form piezoresistors. The resistance of piezoresistors changes with changes in external pressure. However, silicon-based piezoresistive pressure sensors suffer from serious temperature drift and usually can only work at high temperatures. In an environment below 120°C.

The band gap of GaN material is 3.4eV, and it is a kind of good high temperature resistant material, the pressure sensor of GaN material can be applied in the working environment of 600 ℃. The GaN material itself is a piezoelectric material. Using its piezoelectric properties, if metal electrodes are made on the upper and lower surfaces of the pressure material, although the output signal of the upper and lower electrodes will change with the change of pressure, its thickness is generally large, which is not compatible with microelectronics technology. . In addition, the AlGaN/GaN heterostructure forms a two-dimensional electron gas (2DEG) with high concentration and high electron mobility on the surface of the GaN channel layer. Using an AlGaN/GaN heterostructure as a pressure sensor usually requires the use of the two-dimensional electron gas concentration to change with the pressure under the action of an external driving voltage, which requires energy consumption. However, many application scenarios require pressure sensors with extremely low power consumption or even zero power consumption.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. Therefore, an object of the present invention is to provide a pressure-induced barrier-variable gallium nitride pressure sensor and a preparation method thereof. The piezo-induced barrier variable gallium nitride pressure sensor can directly measure the change of the external pressure according to the potential difference between the upper electrode and the lower electrode without an external driving voltage, that is, it can realize the change of the external pressure without an external driving voltage. zero power detection. At the same time, the piezo-induced barrier variable gallium nitride pressure sensor also has the advantages of high temperature resistance.

In one aspect of the present invention, the present invention provides a gallium nitride pressure sensor with variable pressure-induced barrier. According to an embodiment of the present invention, the pressure-induced barrier variable gallium nitride pressure sensor includes: a first substrate and an epitaxial structure, and the epitaxial structure includes a GaN buffer layer, a GaN Channel layer, AlN insertion layer, AlGaN barrier layer, GaN cap layer; wherein, the AlGaN barrier layer has a first groove, and an ohmic contact layer is formed in the first groove, and the ohmic contact layer and The two-dimensional electron gas at the interface of the AlN insertion layer and the GaN channel layer is connected to form a lower electrode; at least part of the upper surface of the GaN cap layer is formed with an upper electrode; and a passivation layer, the passivation layer covers At least part of the upper surface of the epitaxial structure.

In the GaN pressure sensor with variable piezoelectric barrier according to the above-mentioned embodiments of the present invention, due to piezoelectric polarization and self-polarization effects, a high-concentration, high-electron-mobility electrode is formed at the interface between the AlN insertion layer and the GaN channel layer. Two-dimensional electron gas (2DEG), two-dimensional electron gas can be used as the lower electrode of the pressure sensor, the Schottky contact metal layer on the upper surface of the AlGaN barrier layer is used as the upper electrode, and the change of external pressure is reflected by the potential difference between the upper and lower electrodes. On the one hand, using the piezoelectric properties of the AlGaN material, the polarization charges on the upper and lower surfaces of the AlGaN barrier layer are changed by external pressure; on the other hand, the external pressure also bends the energy levels in the quantum well, resulting in a two-dimensional electron gas The charge density in the quantum well changes, thereby changing the potential energy of the upper and lower surfaces of the AlGaN barrier layer, resulting in a pressure-induced barrier change effect. Furthermore, by measuring the electromotive force difference between the upper and lower electrodes and converting the pressure signal into a voltage or potential output, the sensing and detection of pressure can be realized. In this pressure sensor, the two-dimensional electron gas at the interface between the AlN insertion layer and the GaN channel layer is used as the lower electrode, which avoids the technical difficulties of conventionally using metal electrodes as the lower electrode; in addition, the external pressure changes the two-dimensional electron gas quantum The energy level in the trap adjusts the transportation of the two-dimensional electron gas, changes the charge density of the lower electrode, and forms a potential difference between the upper and lower electrodes without consuming energy, so that zero-power consumption detection of external pressure changes can be realized.

In addition, the pressure-induced barrier variable gallium nitride pressure sensor according to the above-mentioned embodiments of the present invention may also have the following additional technical features:

In some embodiments of the present invention, the material of the first substrate is Si, SiC, GaN or sapphire.

In some embodiments of the present invention, the thickness of the GaN buffer layer is 0.5-10 μm.

In some embodiments of the present invention, the thickness of the GaN channel layer is 0.2-10 μm.

In some embodiments of the present invention, the AlN insertion layer has a thickness of 0.5-3 nm.

In some embodiments of the present invention, the thickness of the AlGaN barrier layer is 10-1000 nm, and the depth of the first groove is 10-1000 nm.

In some embodiments of the present invention, the thickness of the GaN cap layer is 0-10 nm.

In some embodiments of the present invention, the material of the upper electrode is selected from at least one of Ti, Cr, Ni, Pt, and Au.

In some embodiments of the present invention, the passivation layer is made of inorganic materials.

In some embodiments of the present invention, the inorganic material is at least one selected from silicon oxide, silicon nitride, and aluminum oxide.

In some embodiments of the present invention, the thickness of the passivation layer is 50-600 nm.

In some embodiments of the present invention, the material of the passivation layer is a low-stress material, and the stress range of the low-stress material is 0-300 MPa.

In some embodiments of the present invention, the passivation layer has electrode holes and external electrodes, and the external electrodes are respectively connected to the upper electrode and the lower electrode through the electrode holes.

In some embodiments of the present invention, there is a second groove on the surface of the first substrate away from the epitaxial structure, and the pressure-induced barrier change GaN pressure sensor further includes: a bonding layer , the second substrate and a reference pressure chamber; the bonding layer is formed on the surface of the first substrate away from the epitaxial structure, and the second substrate is connected to the first substrate through the bonding layer The substrate is bonded and forms the reference pressure cavity with the second groove.

In some embodiments of the present invention, the depth of the second groove is 50-400 μm.

In some embodiments of the present invention, the projected area of the second groove on the first substrate is larger or smaller than the projected area of the upper electrode on the first substrate.

In another aspect of the present invention, the present invention proposes a method for preparing the pressure-induced barrier variable gallium nitride pressure sensor of the above embodiment. According to an embodiment of the present invention, the method includes: (1) forming an epitaxial structure on a first substrate, the epitaxial structure comprising a GaN buffer layer, a GaN channel layer, an AlN an insertion layer, an AlGaN barrier layer, and a GaN cap layer; (2) selectively etching the epitaxial structure to form an epitaxial mesa; (3) selectively etching the AlGaN barrier layer to form the first groove, And prepare an ohmic contact layer connected to the two-dimensional electron gas in the first groove to form a lower electrode; (4) form an upper electrode on at least part of the upper surface of the GaN cap layer; (5) form an upper electrode on the epitaxial A passivation layer is formed on at least part of the upper surface of the structure to obtain the pressure-induced barrier change type gallium nitride pressure sensor. The pressure-induced barrier change gallium nitride pressure sensor prepared by this method can directly measure the change of the external pressure according to the potential difference between the upper electrode and the lower electrode without an external driving voltage, that is, it can be realized without an external driving voltage. Zero-power detection of external pressure changes.

In addition, the method for manufacturing a pressure-induced barrier variable gallium nitride pressure sensor according to the above-mentioned embodiments of the present invention may also have the following additional technical features:

In some embodiments of the present invention, the method further includes: forming electrode holes on the passivation layer, and forming external electrodes respectively connected to the upper electrode and the lower electrode through the electrode holes.

In some embodiments of the present invention, the method further includes: selectively etching at least part of the surface of the first substrate away from the epitaxial structure to form a second groove; A second substrate is bonded to a surface away from the epitaxial structure, so that the second substrate and the second groove form a reference pressure chamber.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Figure 1 is a schematic diagram of the energy band of a pressure-induced barrier-variable gallium nitride pressure sensor;

Fig. 2 is a schematic structural diagram of a pressure-induced barrier variable gallium nitride pressure sensor according to an embodiment of the present invention, wherein a is a schematic diagram of the top surface structure, and b is a schematic diagram of the cross-sectional structure of the A-A' plane in a;

Fig. 3 is a schematic structural diagram of a pressure-induced barrier variable gallium nitride pressure sensor according to an embodiment of the present invention, wherein a is a schematic diagram of the top surface structure, and b is a schematic cross-sectional structure diagram of the A-A' plane in a;

Fig. 4 is a schematic structural diagram of a pressure-induced barrier variable gallium nitride pressure sensor according to an embodiment of the present invention, wherein a is a schematic diagram of the top surface structure, and b is a schematic cross-sectional structure diagram of the A-A' plane in a;

Fig. 5 is a schematic structural diagram of a pressure-induced barrier variable GaN pressure sensor according to an embodiment of the present invention, wherein a is a schematic diagram of the top surface structure, and b is a schematic diagram of the cross-sectional structure of the A-A' plane in a.

Reference signs:

1: upper electrode, 2: lower electrode, 3: AlGaN barrier layer, 4: AlN insertion layer, 5: passivation layer, 6: GaN channel layer, 7: GaN buffer layer, 8: first substrate, 9 : bonding layer, 10: second substrate, 11: reference pressure chamber, 12: GaN cap layer.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " The orientation or positional relationship indicated by "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner" and "outer" are based on the orientation shown in the drawings Or positional relationship is only for the convenience of describing the present invention and simplifying the description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, terms such as "installation", "connection", "connection" and "fixation" should be interpreted in a broad sense unless otherwise clearly specified and limited, for example, it may be a fixed connection or a detachable connection, or integrated; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limited. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature indirectly through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

In one aspect of the present invention, the present invention provides a gallium nitride pressure sensor with variable pressure-induced barrier. The pressure-induced barrier variable gallium nitride pressure sensor according to the embodiment of the present invention will be further described in detail below.

As shown in Figure 1, due to the spontaneous polarization and piezoelectric polarization effects of the AlGaN barrier layer and the GaN channel layer in the AlGaN/GaN heterostructure, a high-concentration, high-electron migration The pressure sensor uses two-dimensional electron gas (2DEG) as the lower electrode, and the ohmic contact layer is connected to the two-dimensional electron gas (2DEG) through selective groove etching of the AlGaN layer, thus avoiding the The electrode requires the use of metal technology, and a metal layer is deposited on the surface of the AlGaN barrier layer as the upper electrode. When external pressure is applied to the device, the polarization charge of the upper and lower electrodes changes due to the piezoelectric effect of the AlGaN material. On the other hand, the energy level barrier at the interface of the AlGaN/GaN heterostructure changes due to external pressure, which also leads The charge density of the two-dimensional electron gas changes, thereby changing the charge barrier difference between the upper and lower electrodes, which is the piezoelectric barrier change effect. Therefore, the change of external pressure is reflected by measuring the potential barrier difference between the upper and lower electrodes, so as to realize the sensing and detection of pressure.

Referring to FIGS. 2 and 3 , according to some embodiments of the present invention, the pressure-induced barrier variable gallium nitride pressure sensor includes: a first substrate 8 and an epitaxial structure, and the epitaxial structure includes sequentially formed on the first substrate 8 . GaN buffer layer 7, GaN channel layer 6, AlN insertion layer 4, AlGaN barrier layer 3, GaN cap layer 12; wherein, AlGaN barrier layer 3 has a first groove, and an ohmic contact is formed in the first groove layer, the ohmic contact layer communicates with the two-dimensional electron gas (2DEG) at the interface between the AlN insertion layer 4 and the GaN channel layer 6 to form the lower electrode 2; at least part of the upper surface of the GaN cap layer 12 is formed with the upper electrode 1; and the blunt The passivation layer 5 covers at least part of the upper surface of the epitaxial structure.

The material of the first substrate 8 is not particularly limited, and can be selected by those skilled in the art according to actual needs. According to some embodiments of the present invention, the material of the first substrate 8 may be Si, SiC, GaN or sapphire.

According to some embodiments of the present invention, the GaN buffer layer 7 may have a thickness of 0.5-10 μm, such as 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, 8 μm, 9 μm, 10 μm and so on. If the thickness of the GaN buffer layer 7 is too small, the dislocation density of the epitaxial layer may be high; if the thickness of the GaN buffer layer 7 is too large, the stress uniformity of the epitaxial layer may be poor.

According to some embodiments of the present invention, the GaN channel layer 6 may have a thickness of 0.2-10 μm, such as 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 5 μm, 8 μm, 9 μm, 10 μm, etc. If the thickness of GaN channel layer 6 is too large, stress distribution may not be uniform.

According to some embodiments of the present invention, the thickness of the above-mentioned AlN insertion layer 4 may be 0.5-3 nm, such as 0.5 nm, 0.8 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm and so on. If the thickness of the AlN insertion layer 4 is too large, extreme stress may be introduced, reducing the epitaxial quality of the AlGaN layer, resulting in reduced mobility.

According to some embodiments of the present invention, the thickness of the above-mentioned AlGaN barrier layer 3 may be 10-1000nm, such as 10nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 800nm, 900nm, 1000nm, etc.; the depth of the first groove 10 to 1000 nm, such as 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 800 nm, 900 nm, 1000 nm, etc. It can be understood that the depth of the first groove can be determined according to the thickness of the AlGaN barrier layer, so as to make the ohmic contact layer formed in the first groove communicate with the two-dimensional electron gas to form the lower electrode. If the thickness of the AlGaN barrier layer 3 is too small, the two-dimensional electron gas density may be low; if the thickness of the AlGaN barrier layer 3 is too large, the carrier mobility may be low.

According to some embodiments of the present invention, the GaN cap layer 12 may have a thickness of 0-10 nm, for example, 0, 0.1 nm, 1 nm, 2 nm, 3 nm, 5 nm, 8 nm, 9 nm, 10 nm and so on. If the thickness of the GaN cap layer 12 is too small, the carrier concentration may be reduced; if the thickness of the GaN cap layer 12 is too large, the contact resistance may be increased and the two-dimensional electron gas mobility may be reduced.

According to some embodiments of the present invention, the material of the upper electrode may be selected from at least one of Ti, Cr, Ni, Pt, and Au.

According to some embodiments of the present invention, the material of the passivation layer may be an inorganic material.

According to some embodiments of the present invention, the inorganic material may be selected from at least one of silicon oxide, silicon nitride, and aluminum oxide.

According to some embodiments of the present invention, the passivation layer 5 may have a thickness of 50-600nm, such as 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm and so on. If the thickness of the passivation layer 5 is too small, the device may not be protected; if the thickness of the passivation layer 5 is too large, it may affect the transport of two-dimensional electron gas.

According to some embodiments of the present invention, the passivation layer is made of a low-stress material, and the stress range of the low-stress material may be 0-300MPa, such as 0, 50MPa, 100MPa, 150MPa, 200MPa, 250MPa, 300MPa, etc. Therefore, the robustness and performance of the device can be improved.

According to some embodiments of the present invention, the passivation layer has electrode holes and external electrodes, and the external electrodes are respectively connected to the upper electrode and the lower electrode through the electrode holes. Thus, the potential difference between the upper electrode and the lower electrode can be obtained by connecting the upper electrode and the lower electrode in the pressure sensor to the external potential measurement unit through the two external electrodes respectively. Among them, the external electrodes can be patterned according to actual needs.

Referring to FIGS. 4 and 5 , according to some embodiments of the present invention, in the piezobarrier variable gallium nitride pressure sensor, there is a second groove on the surface of the first substrate 8 away from the epitaxial structure, and the piezobarrier The variable GaN pressure sensor may further include: a bonding layer 9 , a second substrate 10 and a reference pressure chamber 11 . The bonding layer 9 is formed on the surface of the first substrate 8 away from the epitaxial structure. The second substrate 10 is bonded to the first substrate 8 through the bonding layer 9 and forms a reference pressure cavity 11 with the second groove. Therefore, when measuring external pressure, the reference pressure chamber 11 can be used as a pressure reference, and the formed pressure sensor is a gauge pressure sensor. The bonding manner between the second substrate 10 and the first substrate 8 may be, for example, direct bonding, anodic bonding, metal interlayer bonding, polymer bonding, and the like.

Correspondingly, without the bonding layer 9 , the pressure sensor with structures such as the second substrate 10 and the reference pressure chamber 11 is a differential pressure sensor.

The material of the second substrate 10 is not particularly limited, and can be selected by those skilled in the art according to actual needs. According to some embodiments of the present invention, the material of the second substrate 10 may be silicon, glass, sapphire and the like.

According to some embodiments of the present invention, the depth of the second groove may be 50-400 μm, such as 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm and so on. It can be understood that the depth of the second groove is the depth of the reference pressure chamber 11 formed after bonding the second substrate 10 , and the depth of the second groove can be determined according to the required range of the pressure sensor.

In addition, according to some embodiments of the present invention, in a pressure sensor without a bonding layer 9, a second substrate 10 and a reference pressure chamber 11, the surface of the first substrate 8 away from the epitaxial structure can also be A second groove is formed.

According to some embodiments of the present invention, the projected area of the second groove on the first substrate can be larger than the projected area of the upper electrode on the first substrate (as shown in Figures 2 and 4), and can also be smaller than the projected area of the upper electrode. The projected area on the first substrate (as shown in Figures 3 and 5).

According to some embodiments of the present invention, the specific shape of the front electrode structure is not particularly limited, for example, it may be a circle, a square or other figures, and the front electrode structure shown in FIGS. 2-5 is a circle.

In another aspect of the present invention, the present invention proposes a method for preparing the pressure-induced barrier variable gallium nitride pressure sensor of the above embodiment. According to an embodiment of the present invention, the method includes: (1) forming an epitaxial structure on a first substrate, and the epitaxial structure includes a GaN buffer layer, a GaN channel layer, an AlN insertion layer, an AlGaN barrier layer and GaN cap layer; (2) selectively etching the epitaxial structure to form an epitaxial mesa; (3) selectively etching the AlGaN barrier layer to form the first groove, and preparing the second groove in the first groove (4) forming an upper electrode on at least part of the upper surface of the GaN cap layer; (5) forming a passivation layer on at least part of the upper surface of the epitaxial structure to obtain a piezoelectric barrier Variable gallium nitride pressure sensor. The pressure-induced barrier change gallium nitride pressure sensor prepared by this method can directly measure the change of the external pressure according to the potential difference between the upper electrode and the lower electrode without an external driving voltage, that is, it can be realized without an external driving voltage. Zero-power detection of external pressure changes.

According to some embodiments of the present invention, the above method further includes: forming electrode holes on the passivation layer, and forming external electrodes respectively connected to the upper electrode and the lower electrode through the electrode holes. Thus, the potential difference between the upper electrode and the lower electrode can be obtained by connecting the upper electrode and the lower electrode in the pressure sensor to the external potential measurement unit through the two external electrodes respectively. Among them, the external electrodes can be patterned according to actual needs.

According to some embodiments of the present invention, the above method further includes: selectively etching at least part of the surface of the first substrate away from the epitaxial structure to form a second groove; and the second substrate, so that the second substrate and the second groove form a reference pressure chamber. Therefore, when measuring external pressure, the reference pressure chamber can be used as a pressure reference, and the formed pressure sensor is a gauge pressure sensor. The specific manner of bonding the second substrate on the surface of the first substrate away from the epitaxial structure may be, for example, direct bonding, anode bonding, metal interlayer bonding, polymer bonding, and the like.

In addition, it should be noted that all the features and advantages described above for the piezo-induced barrier change type gallium nitride pressure sensor are also applicable to the method for preparing the piezo-induced barrier change type gallium nitride pressure sensor. Let me repeat them one by one.

The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are only illustrative and do not limit the present invention in any way.

Example

(1) Select a Si substrate, pretreat the surface, and grow a 2 μm GaN buffer layer;

(2) On the GaN buffer layer, grow a 2μm GaN channel layer, a 2nm AlN insertion layer, a 200nm AlGaN barrier layer and a 3nm GaN cap layer;

(3) Inductively coupled plasma (ICP) etching equipment is used to selectively etch the epitaxial structure of the epitaxial layer to form an etching mesa, and the etching depth reaches the GaN channel layer;

(4) Using ICP etching equipment to selectively etch the groove of the AlGaN barrier layer on the mesa, the etching depth is 180nm, and prepare the ohmic contact layer to communicate with the two-dimensional electron gas (2DEG) to form the lower electrode;

(5) Depositing a metal layer (Ni/Au) on the GaN cap layer to form an upper electrode;

(6) Deposit a low-stress passivation layer of silicon nitride 300nm, and etch to form an electrode hole, then deposit a metal layer (Ti/Au) and pattern it to form an interconnected electrode;

(7) Through the deep silicon etching process, the Si substrate is selectively etched to form an etching groove, and the etching depth is 350 μm;

(8) Select an appropriate bonding process to bond the GaN epitaxial wafer to another substrate to form a gauge pressure sensor.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (17)

1. A piezoelectric barrier variable gallium nitride pressure sensor, comprising:

the GaN-based epitaxial structure comprises a first substrate and an epitaxial structure, wherein the epitaxial structure comprises a GaN buffer layer, a GaN channel layer, an AlN insert layer, an AlGaN barrier layer and a GaN cap layer which are sequentially formed on the first substrate; the AlGaN barrier layer is provided with a first groove, an ohmic contact layer is formed in the first groove, and the ohmic contact layer is communicated with two-dimensional electrons at the interface of the AlN insert layer and the GaN channel layer to form a lower electrode; an upper electrode is formed on at least part of the upper surface of the GaN cap layer;

a passivation layer covering at least a portion of an upper surface of the epitaxial structure.

2. The piezobarrier-changing gallium nitride pressure sensor according to claim 1, wherein the material of the first substrate is Si, siC, gaN or sapphire.

3. The piezobarrier-changing gallium nitride pressure sensor according to claim 1, wherein the thickness of the GaN buffer layer is 0.5 to 10 μm.

4. The piezobarrier-changing gallium nitride pressure sensor according to claim 1, wherein the thickness of the GaN channel layer is 0.2 to 10 μm.

5. The piezoelectric barrier variable gallium nitride pressure sensor according to claim 1, wherein the AlN insertion layer has a thickness of 0.5 to 3nm.

6. The pressure-induced barrier variable gallium nitride pressure sensor according to claim 1, wherein the AlGaN barrier layer has a thickness of 10 to 1000nm, and the first groove has a depth of 10 to 1000nm.

7. The pressure-induced barrier variable gallium nitride pressure sensor according to claim 1, wherein the thickness of the GaN cap layer is 0 to 10nm.

8. The pressure-induced barrier variable gallium nitride pressure sensor according to claim 1, wherein the material of the upper electrode is at least one selected from Ti, cr, ni, pt, and Au.

9. The piezobarrier-changing gallium nitride pressure sensor according to claim 1, wherein the material of the passivation layer is an inorganic material.

10. The piezobarrier-changing gallium nitride pressure sensor according to claim 9, wherein the inorganic material is selected from at least one of silicon oxide, silicon nitride, and aluminum oxide.

11. The piezoelectric barrier variable gallium nitride pressure sensor according to claim 1, wherein the thickness of the passivation layer is 50-600 nm.

12. The piezobarrier-changing gallium nitride pressure sensor according to claim 1, wherein the passivation layer is made of a low-stress material, and the stress range of the low-stress material is 0-300 MPa.

13. The piezoresistive varying gallium nitride pressure sensor according to claim 1, wherein the passivation layer has an electrode hole and an external electrode, and the external electrode is connected to the upper electrode and the lower electrode through the electrode hole.

14. The piezobarrier-change gallium nitride pressure sensor according to any one of claims 1 to 13, wherein a surface of the first substrate on a side away from the epitaxial structure has a second groove thereon, the piezobarrier-change gallium nitride pressure sensor further comprising: a bonding layer, a second substrate and a reference pressure chamber;

the bonding layer is formed on one side surface of the first substrate far away from the epitaxial structure, the second substrate is bonded with the first substrate through the bonding layer, and the second substrate and the second groove form the reference pressure cavity;

optionally, the depth of the second groove is 50-400 μm;

optionally, a projected area of the second groove on the first substrate is larger or smaller than a projected area of the upper electrode on the first substrate.

15. A method of manufacturing the piezoelectric barrier change gallium nitride pressure sensor according to any one of claims 1-14, comprising:

(1) Forming an epitaxial structure on a first substrate, wherein the epitaxial structure comprises a GaN buffer layer, a GaN channel layer, an AlN insert layer, an AlGaN barrier layer and a GaN cap layer which are sequentially formed on the first substrate;

(2) Selectively etching the epitaxial structure to form an epitaxial table top;

(3) Selectively etching the AlGaN barrier layer to form the first groove, and preparing an ohmic contact layer communicated with two-dimensional electron gas in the first groove to form a lower electrode;

(4) Forming an upper electrode on at least part of the upper surface of the GaN cap layer;

(5) And forming a passivation layer on at least part of the upper surface of the epitaxial structure to obtain the piezobarrier-variable gallium nitride pressure sensor.

16. The method of claim 15, further comprising: and forming an electrode hole on the passivation layer, and forming external electrodes respectively connected with the upper electrode and the lower electrode through the electrode hole.

17. The method of claim 15, further comprising: selectively etching at least part of the surface of one side of the first substrate, which is far away from the epitaxial structure, to form a second groove; and bonding a second substrate on the surface of one side of the first substrate, which is far away from the epitaxial structure, so that the second substrate and the second groove form a reference pressure cavity.

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