WO2017088560A1

WO2017088560A1 - Sensor, preparation method and multi-sensor system

Info

Publication number: WO2017088560A1
Application number: PCT/CN2016/098989
Authority: WO
Inventors: 圣阿加塔法比奥; 耶尔沃利诺艾莉娜; 索科洛夫斯基罗伯特; 董明智; 张国旗
Original assignee: 北京代尔夫特电子科技有限公司
Priority date: 2015-11-26
Filing date: 2016-09-14
Publication date: 2017-06-01
Also published as: CN105424780B; CN105424780A

Abstract

A sensor, a preparation method and a multi-sensor system. The sensor comprises a substrate and a transistor located thereon of a group III nitride-based HEMT structure, wherein a source electrode and a drain electrode of the transistor are both arranged on a semiconductor in a top layer of the transistor, a surface of a gate electrode has a functionalized film obtained through a functionalization treatment, and a bare gate electrode region between the source electrode and the drain electrode forms a sensing region. By detecting a current change in the sensing region, density detection on an object to be detected which is in contact with the sensing region is realized.

Description

Sensor, preparation method and multi-sensor system

Technical field

The present disclosure relates to the field of sensor technology, for example, to a sensor, a method of fabrication, and a multi-sensor system.

Background technique

In the atmosphere and gas supply systems, the detection of chemical constituents of pollutants and biological water components is extremely important for environmental protection and health care. For example, in the harmful gas transport system, rapid detection of gas leakage plays a key role in protecting workers' health and safety and environmental pollution.

In addition, chemical sensing can also detect whether surface water and drinking water contain heavy metals, organic pollutants, inorganic pollutants, industrial pollutants and other related liquid properties (such as pH, salinity, turbidity and Smell, etc.). In addition, by detecting the body fluid (blood, saliva) and gas (breathing) of the human body, it is possible to effectively predict various diseases that endanger human life.

The gaseous liquid chemical analysis systems used in the above various types of tests usually require chromatography, mass spectrometry, X-ray fluorescence analysis or calorimetry. These analyses are performed in the laboratory and are expensive to promote. Therefore, a portable small sensing system was developed to achieve personal health tracking, monitoring the quality of the atmosphere and water.

In the related art, a silicon-based sensor is used as a sensor based on a semiconductor material, and the manufacturing technology of the silicon-based sensor is mature and the cost is controllable. However, the shortcomings of the silicon-based sensor are: the detection sensitivity is not high enough, in applications requiring high sensitivity, such as environmental detection, medical application detection, etc., silicon-based sensors cannot meet the detection requirements; silicon-based sensors are difficult to be harsh Working under environmental conditions, such as high temperature, high humidity, high pressure, etc.; and limited by the material properties of silicon, the size of silicon-based sensors is large, and for silicon or even wearable applications, the silicon-based sensors often fail to meet the requirements.

Therefore, in the related art, the silicon-based sensor has defects such as low detection sensitivity, small application range, and poor portability.

Summary of the invention

The present disclosure proposes a sensor, a preparation method, and a multi-sensor system by using a group III nitride group Functional processing and optimization processing of the transistor sensing region of the HEMT (High Electron Mobility Transistor) structure.

In one aspect, the present disclosure provides a sensor comprising: a substrate, and a transistor of a group III nitride-based HEMT structure thereon; wherein a source and a drain metal of the transistor are disposed on a semiconductor on a top layer of the transistor The gate surface has a functionalized film obtained by functionalization, and a exposed gate region between the source and the drain forms a sensing region; and the functionalization is realized by detecting a current change of the sensing region The concentration of the analyte to be detected in contact with the membrane is detected.

Optionally, the transistor comprises: at least one group III nitride heterojunction, one side of the group III nitride heterojunction is GaN, and the other side is binary, ternary or multivariate III different from GaN Family nitride.

Optionally, the group III nitride heterojunction comprises: a buffer layer on the substrate, the buffer layer as a current channel, the composition of which is GaN; and a barrier layer on the buffer layer The composition of the barrier layer contains a multi-component group III nitride or ZnO and/or an intrinsic material; the buffer layer and the composition of the barrier layer interact to form a 2DEG at the interface of the buffer layer and the barrier layer; The ohmic on the barrier layer contacts the source and the drain metal, and the exposed barrier layer between the ohmic contact source and the drain metal is a sensing region, and the functionalized film is coated on the sensing region; An insulating layer covering the ohmic contact source and drain metal, the 2DEG and the barrier layer, and embedded in the buffer layer near the barrier layer side.

Optionally, the transistor further includes: a cover layer overlying the barrier layer, the composition of the cover layer being doped or using an intrinsic material, interacting with the barrier layer, on the cover layer An ohmic contact source and a drain metal are formed; a bare cap layer between the ohmic contact source and the drain metal is a sensing region; and the insulating layer is also coated on the periphery of the cap layer.

Optionally, the plurality of group III nitrides in the barrier layer include any one of GaN, InN, AlN, AlGaN, InGaN, and Al InGaN; and/or the insulating layer includes an insulating metal, an insulating oxide Any one of high molecular weight polymers.

Optionally, the substrate comprises: an extrinsic semiconductor substrate and a group III nitride grown on the extrinsic semiconductor substrate row, the extrinsic semiconductor comprising silicon, silicon carbide, sapphire and nitrogen Any one of the aluminum; and/or the functionalized film, including any one or more of an oxide, a metal thin film, a nano material, a semiconductor, a nitride, an organic biomaterial, an inorganic material, and a polymer material .

In accordance with the above-described sensor, another aspect of the present disclosure provides a multi-sensor system including: at least two of the sensors, and a main control circuit; the at least two sensors are connected in parallel with the main control circuit and Between the objects to be detected; the output signal of the sensor is performed by the main control circuit Control and analysis to achieve concentration detection of the object to be detected.

The present disclosure further provides a method for fabricating the above-mentioned sensor, comprising: forming a separate mesa structure on the epitaxial wafer by plasma etching; and sequentially removing the mesa structure based on the mesa structure a surface oxide treatment, a metal precipitation and patterning treatment, and a high temperature annealing treatment, forming an ohmic contact source and a drain metal on top of the mesa structure; and a mesa structure having an ohmic contact source and a drain metal formed on the top, Performing ohmic contact insulation and metal deposition inter-contact contact processing, and interconnect metal deposition and forming processes in sequence, forming a sensing region between the ohmic contact source and the drain metal at the top of the mesa structure; on the sensing region The functionalized film is formed to form a functionalized film; the mesa structure having the ohmic contact source and drain metal and the functionalized film formed by the foregoing process is subjected to metal interpenetrating insulation or encapsulation processing to obtain the sensor.

Optionally, the method further includes: when the sensor adopts AlGaN as a barrier layer, performing a groove etching process on the sensing region formed by the foregoing process to reduce the thickness of the sensing region to be required for detection value.

The solution of the present disclosure is to functionalize the exposed gate region between the source and the drain of the transistor of the III-nitride-based HEMT structure (for example, functionalizing the gate surface of the transistor of the GaN-based HEMT structure) Membrane), when the gate region is in contact with the analyte to be detected, the current between the source and the drain changes significantly, and the purpose of detecting the concentration of the analyte is realized by detecting the change of the current, and the volume of the sensor is small. The detection reliability is high and the accuracy is good.

Optionally, in the solution of the present disclosure, by performing recess etching on the sensing region or thinning the thickness of the sensing layer, the response time of the sensor, the detection range, and the sensitivity of the operation can be shortened.

Therefore, the solution of the present disclosure solves the processing of the transistor sensing region of the III-nitride-based HEMT structure, better realizes the concentration detection of the analyte in contact with the sensing region, improves the detection effect, and reduces the detection difficulty. The problem is, thus, to overcome the drawbacks of the related art that the sensor has low sensitivity, small detection range, and poor portability.

The technical solutions of the present disclosure will be described in the following with reference to the accompanying drawings and embodiments.

DRAWINGS

The drawings are intended to provide an understanding of the embodiments of the invention, and are in the In the drawing:

1 is a cross-sectional structural view of an embodiment of a gallium nitride sensor of the present disclosure;

2 is a transmission process of the optimization process for reducing the thickness of the barrier layer by reducing the thickness of the barrier layer in the present disclosure. Schematic diagram of the cross section of the sensor;

3 is a schematic cross-sectional structural view of a sensor obtained by an optimized process for reducing a thickness of a detection region of a gate exposed region by reducing the thickness of a gate exposed region;

4 is a schematic diagram showing the working principle of an embodiment of the multi-sensor system of the present disclosure;

5 is a schematic cross-sectional structural view showing the results of processing in each step of the method for fabricating a gallium nitride sensor according to the present disclosure, wherein (a) is an epitaxial wafer structure epitaxially grown on a substrate, and (b) is a structure obtained by plasma etching treatment. (c) is the structure obtained by the ohmic contact treatment, (d) is the structure obtained by the ohmic contact insulation treatment, (e) is the structure obtained by the external lead metal deposition and forming treatment, and (f) is the structure obtained by the groove etching treatment, (g) The resulting structure is treated with an outer lead metal insulation, and (h) is a structure obtained by coating the functionalized film of the sensing region;

6 is a schematic top plan view of a gallium nitride sensor of the present disclosure.

With reference to the accompanying drawings, the reference numerals in the embodiments of the present disclosure are as follows:

1-sensor; 2-exotic semiconductor substrate; 3-buffer layer; 4-two-dimensional electron gas; 5-block layer; 6-cover layer; 7-ohm contact source and drain metal; 8--insulation layer 9-plasma etching of the side (edge) of the structure; 10 - sensing area; 11 - functionalized film; 12 - mesa; 13 - epitaxial layer; 14 - pad.

Implementation

In order to make the objects, technical solutions and advantages of the present disclosure more clear, the related technical solutions of the present disclosure will be described below in conjunction with the alternative embodiments of the present disclosure and the corresponding drawings. The described embodiments are only a part of the embodiments of the present disclosure, and not all of the embodiments.

The embodiment of the present disclosure provides a sensor. Illustratively, the sensor is a gallium nitride sensor as an example. FIG. 1 is a schematic cross-sectional structural view of an embodiment of the GaN sensor of the present disclosure. The sensor includes at least:

a substrate, and a III-nitride (eg, gallium nitride GaN)-based HEMT structure transistor on the substrate; wherein the source and drain metal 7 of the transistor are disposed over the semiconductor on the top of the transistor, the source The gate region between the pole and the drain forms the sensing region 10, and the surface of the gate region is provided with a functionalized film 11 obtained by functionalization; by detecting the current change of the sensing region 10, the pairing and functionalization are realized. The concentration of the analyte to be detected that is contacted by the membrane 11 is detected. By using a GaN-based HEMT structure The body tube can reduce the volume of the sensor and also improve the detection sensitivity of the sensor.

In one example, the outer surface of the transistor is a layer of semiconductor material, and the source and drain metal of the transistor (eg, ohmic contact source and drain metal 7) extend out of the semiconductor material layer (eg, disposed on the top semiconductor material) Above, the gate is located between the source and the drain, the gate region between the source and the drain can serve as the sensing region 10, and the gate surface is functionalized to form the functionalized film 11. The current between the source and the drain is conducted by 2 Dimensional Electron Gas (2DEG), which is derived from the polarization effect formed by two different Group III nitride stacks. The sensing function is realized by the cooperation of the gate region 10 between the source and the drain and the functionalized film 11. When the functionalized film 11 is in contact with the analyte to be detected, the current between the source and the drain changes, and the detection is performed. The change in current determines the concentration of the analyte being detected.

Here, it should be understood by those skilled in the art that in the gallium nitride sensor of the embodiment of the present disclosure, the transistor includes a source, a drain, and a gate. Wherein the source and the drain are metal materials formed on the top semiconductor material, the metal material forming an ohmic contact with the top semiconductor material. To ensure that the contact resistance between the source and drain metal and the semiconductor material is sufficiently small. The gate region is located between the source and the drain metal, and the functionalized film 11 is formed on the gate region. When the analyte to be detected contacts the functionalized film 11, the current in the gate region changes. And there is a correspondence between the current change and the concentration of the analyte to be detected. Therefore, the concentration of the analyte to be detected can be determined by detecting the change in current of the gate region.

The above analysis shows that in the embodiment of the present disclosure, the functionalized film is in contact with the analyte to be detected, and the gate region of the transistor can be free of applied voltage, so the material of the gate region can be a top semiconductor material or a top semiconductor material. Metal material. The material of the gate region is not limited here, and can be flexibly set according to actual needs in the manufacturing process of the GaN transistor. In the embodiment of the present disclosure, the case where the gate region is the top semiconductor material is taken as an example.

The substrate includes: an extrinsic semiconductor substrate 2 and a group III nitride extrinsic semiconductor grown on the extrinsic semiconductor substrate 2, including any one of silicon, silicon carbide, sapphire, and aluminum nitride. . The epitaxial growth needs to be applied to Molecular Beam Epitaxy (MBE) or Metal-Organic Chemical Vapor Deposition (MOCVD).

The functionalized film 11 includes any one or more of an oxide, a metal thin film, a nano material, a semiconductor, a nitride, an organic biomaterial, an inorganic material, and a polymer material.

For example: functionalized membrane 11: The sensor is capable of detecting target contaminants in the analyte to be detected, and at least detecting contaminants that are frequently present in the analyte to be detected. Wherein, the detection of the target contaminant can be achieved by a functionalized film on the sensing region 10, which can be a functionalized coating that can be responsible for analyzing and detecting a target contaminant. The constituent materials of the functionalized film referred to in the present disclosure include, but are not limited to, any one or more of the following materials:

Pure or doped oxide, metal film (such as Pt, Au, Ag), nano materials (such as carbon nanotubes (CNT), graphene, ZnO nanorods, etc.), nanoparticles, semiconductors (such as InN, pure An oxide semiconductor or a doped oxide semiconductor), a nitride (such as SiN, TiN), an organic biomaterial (such as an ionophore), an inorganic material, a polymer material, and a combination thereof.

In one embodiment, the transistor comprises: at least one group III nitride heterojunction, one side of the group III nitride heterojunction is a group III nitride GaN, and the other side is a binary, ternary or other than GaN Multi-component III nitride. Illustratively, as shown in FIG. 1, the transistor includes a group III nitride heterojunction, one side of which is a buffer layer 3, which is composed of a GaN material, and the other side is a barrier layer 5, which is composed of a binary III. The group nitride aluminum nitride (AlN) or indium nitride (InN) is formed, or the barrier layer 5 may be composed of a group III nitride aluminum gallium nitride (AlGaN) or gallium indium nitride (InGaN).

In one embodiment, as shown in FIG. 1, the transistor includes:

The buffer layer 3 on the substrate can reduce stress, reduce defect density and function as electrical insulation, and the buffer layer 3 can be used as a current channel, and its composition can be selected as GaN;

a barrier layer 5 on the buffer layer 3, the composition of the barrier layer 5 may contain a multi-component group III nitride or ZnO and/or an intrinsic material; the components of the buffer layer 3 and the barrier layer 5 interact with each other in the buffer layer 3 and the barrier layer The interface of 5 forms 2DEG 4;

The ohmic contact source and drain metal 7 on the barrier layer 5, the exposed barrier layer between the ohmic contact source and the drain metal 7 is the sensing region 10, and the functionalized film 11 is coated on the sensing region 10; as well as,

The insulating layer 8 covering the periphery of the ohmic contact source and drain metal 7, 2DEG 4 and the barrier layer 5 and embedded in the buffer layer 3 near the barrier layer 5 is covered.

Among them, the insulating layer 8 simultaneously encloses the edge 9 to achieve a better insulating effect.

In one example, the material of the buffer layer 3 may be an intrinsic semiconductor material, or a doped intrinsic semiconductor material may also be employed.

2DEG refers to the phenomenon that electron gas can move freely in two dimensions and is restricted in the third dimension. 2DEG is the basis for the operation of many field effect devices (eg MOSFET, HEMT, etc.). For example, in the above-mentioned Group III nitride heterojunction, 2DEG 4 is due to the piezoelectric and spontaneous polarization effects at the interface of two materials having different energy bands and lattice constants, so that the GaN and the barrier layer of the buffer layer 3 The AlGaN interaction of 5, the current-carrying electron concentration of the conductive channel is thus increased, thereby forming an electron gas. And the electron gas can only move in a two-dimensional direction, so it is called 2DEG. In the HEMT structure, 2DEG 4 spontaneously forms and is self-sustaining, without the need for an external gate bias, referred to as the "depletion" mode.

Ohmic contact means that the resistance of the metal-to-semiconductor contact surface is much smaller than the resistance of the semiconductor itself, so that during the operation of the transistor, most of the voltage drop occurs in the active region rather than in the metal-to-semiconductor contact surface. For example, as shown in FIG. 1, a source and a drain metal layer are formed on the barrier layer 5, and a suitable metal is selected such that the contact resistance between the metal layer and the barrier layer 5 is much smaller than the resistance value of the barrier layer 5 itself, thereby The contact of the source and drain with the barrier layer 5 is achieved as an ohmic contact. Alternatively, the barrier layer 5 may be a group III nitride semiconductor material, and forming an ohmic contact with the semiconductor material generally requires the use of a Ti/Al metal compound or a Ti/Al/X/Au metal stack, where X may be Ni, Ti, Any of Mo or Pt elements. In addition, the metal material forming an ohmic contact with the barrier layer 5 may not contain a "gold" element to avoid "gold contamination" of the process of growing metal on the barrier layer 5, and metal compounds which may be used without "gold" ohmic contact include Ti/Al/Ti/TiN, Ti/Al/TiN, Ti/Al/W, Ta/Si/Ti/Al/Ni/Ta or Ta/Al/Ta. Forming the ohmic contact metal layer on the barrier layer 5 can be performed by a conventional metal thin film deposition method (e.g., electron beam evaporation, sputtering, etc.) by a high temperature annealing technique.

Insulation Layer 8: The reliability of the ohmic contact metal layer 7 package is related to the lifetime of the sensor. The insulating layer 8 can prevent the ohmic contact metal layer 7 from contacting each other with gas or liquid, thereby avoiding short circuit between the source and the drain of the transistor, prolonging the service life of the sensor, and improving the accuracy of the sensor operation. In addition, transistors with poor insulation will cause drift in sensor performance. Insulation methods that are feasible in the present disclosure include deposition of oxides, deposition of high molecular weight polymers, other organic or inorganic materials.

The sensing region 10 and the functionalized film 11: the sensing region 10 may be a barrier layer 5 between the source and the drain or an unprocessed surface region of the cover layer 6 on which a functionalized process is formed. Functionalized film 11. The functionalized membrane 11 can be in direct contact with the analyte to be detected. The interaction of the analyte to be detected changes the surface charge density of the sensing region, resulting in a difference in current density in the channel, resulting in a change in the magnitude of the current in the channel. Therefore, it is possible to detect the concentration of the analyte to be detected by detecting the magnitude of the current in the channel.

Among them, the group III nitride in the barrier layer 5 includes any one of GaN, InN, AlN, AlGaN, InGaN, and Al InGaN. Wherein, when AlGaN is used, the thickness of the barrier layer 5 is 15-35 nm, and the molar ratio of the Al element is 15-35%; when AlN is used, the thickness of the barrier layer 5 is 2-8 nm, which is thinner than that of AlGaN when used.

Thus, by providing the barrier layer 5, the sensing region 10 can be optimized, and the lower limit of the detection range can be reduced, which is advantageous for the detection of trace substances. The vertical distance of the sensing area 10 from the 2DEG 4 affects the sensitive range of the sensor. The smaller the vertical distance between the sensing region 10 and the 2DEG 4, the higher the detection sensitivity of the sensor, that is, the lower limit of the detection range is low, and the substance having a low content in the analyte to be detected can be detected. This will facilitate the detection of traces of chemical constituents in the analyte to be detected. For example, the response time of the sensor is shortened by the recess etching of the sensing area or the thinning of the sensing layer, and the detection range and sensitivity are improved.

In one example, the response time of the sensor is shortened by thinning the sensing layer, and the detection range and sensitivity are improved. In the embodiment of the present disclosure, the barrier layer serves as a sensing layer of the sensor. As shown in FIG. 2, when the barrier layer 5 is made of a GaN material, the thickness of the barrier layer 5 can be minimized during epitaxial growth to improve the detection range of the sensor. And sensitivity. However, such a method of reducing the response time of the sensor by thinning the sensor is not universal. First, considering the stability of the epitaxial structure of the sensor, the thickness of the barrier layer 5 cannot be infinitely reduced. Second, compared with the barrier layer formed of GaN material, when the barrier layer is formed by using an AlN material, the thickness of the barrier layer is small, and the method of shortening the response time of the sensor by thinning the sensor is not obvious.

In another example, the response time of the sensor is shortened by the concave etching of the sensor area, and the detection range and sensitivity are improved. Referring to FIG. 3, under the premise of maintaining the thickness of the barrier layer 5 in the epitaxial structure, the thickness of the bare region of the sensor gate is reduced during the preparation phase of the sensor, and a "concave gate" structure is formed in the exposed region of the gate by etching technology. It also plays a role in shortening the distance between the analyte to be detected and 2DEG 4.

Optionally, barrier layer 5 includes, but is not limited to, a Group III nitride material and alloys thereof. The material may be any one of binary alloy GaN, InN, AlN, ternary alloy AlGaN, InGaN, and quaternary alloy Al InGaN. A ZnO material is also used as the barrier layer 5 in some structures. The barrier layer 5 can be doped or an intrinsic material can be used.

Moreover, it should be understood by those skilled in the art that the thickness of the barrier layer 5 described above is merely illustrative, and the thickness of the barrier layer 5 can be flexibly set according to material properties and sensor performance during sensor manufacturing.

Optionally, the insulating layer 8 includes any one of an insulating oxide and a high molecular polymer.

Optionally, the group III nitride heterojunction further comprises: a capping layer 6 overlying the barrier layer 5, the component of the capping layer 6 being doped or interacting with the barrier layer 5 using an intrinsic material. An ohmic contact source and drain metal 7 are formed on the cap layer 6; a bare cap layer between the ohmic contact source and the drain metal 7 is a sensing region 10 (also referred to as a gate region); and an insulating layer 8 is also wrapped around the periphery of the cover layer 6.

For example, the cover layer 6 may be located above the barrier layer 5, and the material constituting the cover layer 6 may be doped or intrinsic material. By providing the cover layer 6, the flatness of the sensor surface can be improved, and the resistance of ohmic contacts (for example, ohmic contact source and drain metal 7) can be reduced.

Wherein, the thickness of the cover layer may be 1-3 microns.

Through a large number of experiments, it is possible to increase the sensor by growing a group III nitride (such as gallium nitride) semiconductor gallium nitride transistor on a substrate (for example, extrinsic semiconductor substrate 2) by using the technical solution of the present embodiment. The detection sensitivity enables sensor miniaturization and expands its application area and potential.

Embodiments of the present disclosure also provide a multi-sensor system corresponding to a sensor. Illustratively, this embodiment is described by taking the sensor as a gallium nitride sensor as an example. See Figure 4 for a schematic block diagram of an embodiment of the system of the present disclosure. The system includes:

At least two of the above sensors, and a main control circuit; the at least two sensors are connected in parallel, the main control circuit connected in parallel is connected with the main control circuit and the analyte to be detected; and the main control circuit is used for the sensor The output signal is controlled and analyzed to achieve concentration detection of the analyte to be detected.

For example, one sensor 1 of the multi-sensor system may include an extrinsic semiconductor substrate 2 and a buffer layer 3. Among them, the composition of the buffer layer 3 is GaN as a current path. The upper layer of GaN is a barrier layer 5 containing an AlGaN component. The interaction of GaN and AlGaN forms 2DEG 4 at the interface of GaN. The barrier layer 5 is further covered with a thin cover layer 6 (for example, the composition contains GaN), and an ohmic contact source and a drain metal 7 are formed on the cover layer 6. An insulating layer 8 is provided outside each layer. A functionalized film 11 obtained by functionalization is formed on the sensing region 10, and the functionalized film 11 is in sufficient contact with the analyte to be detected (ambient gas, liquid or other medium) to achieve specific substance analysis. The functionalized film may be a noble metal or a polymer coating.

Thus, by adjusting the structure of the sensor, a series of sensors with different detection ranges are formed, which are combined into a sensor system, and parallel settings (for example: parallel) play a role in the sensor system. Through the use of multiple sensors, the range detectable by the system can be expanded, and the overall detection accuracy of the system can be improved.

Since the processing and functions implemented by the system of the present embodiment substantially correspond to the foregoing embodiments, principles, and examples of the sensors shown in FIG. 1 to FIG. 5, the description of the present embodiment is not exhaustive, and reference may be made to the foregoing embodiments. Related instructions in .

It has been verified by a large number of experiments that the technical solution of the present embodiment can solve the problem that the upper limit of the detection range of the sensor is also reduced to some extent due to the optimization of the sensor, that is, the detection range moves to the micro direction as a whole. thereby. For many applications, the upper limit of the detection range is not of interest and therefore does not cause problems; for certain applications that are concerned with both the upper and lower limits of the detection range, the present disclosure now provides a solution based on the aforementioned sensors.

Embodiments of the present disclosure also provide a method of preparing a sensor. Illustratively, this embodiment is described by taking the sensor as a gallium nitride sensor as an example. The method includes:

Step 1. Using a plasma etching method, a separate mesa structure is formed on the epitaxial wafer.

Among them, the sensor fabrication begins by epitaxially growing a group III nitride on the extrinsic semiconductor substrate 2. However, it will be understood by those skilled in the art that epitaxial growth techniques are not necessary in the disclosed embodiments, and related epitaxial wafers may be provided by third party vendors. The epitaxial wafer structure may be as shown in FIG. 5(a), and the epitaxial wafer includes an extrinsic semiconductor substrate 2, a buffer layer 3, a 2DEG 4, a barrier layer 5, and a cover layer 6 which are sequentially stacked from bottom to top (for example, the composition is GaN).

Wherein, a separate mesa structure is formed on the epitaxial wafer, and the mesa structure can be used for subsequent For the setting of the main body of the sensor, see Figure 5(b).

Step 2, based on the mesa structure, sequentially removing the surface layer oxide treatment, the metal precipitation and patterning treatment, and the high temperature annealing treatment, forming an ohmic contact source and a drain metal 7 on the top of the mesa structure, see FIG. 5(c).

Step 3. Based on the mesa structure in which the ohmic contact source and the drain metal 7 are formed on the top, the ohmic contact insulation and the metal deposition inter-contact contact process, and the interconnection metal deposition and forming process are sequentially performed, and the ohmic contact at the top of the mesa structure is performed. A gate region (ie, sensing region 10) is formed between the source and drain metal 7.

Alternatively, the ohmic contact insulation may be an insulating layer formed on the ohmic contact source and drain metal, the 2DEG and the barrier layer periphery, and the buffer layer near the barrier layer, respectively, over the ohmic contact source and drain metal, respectively. Leave a window for the outer leads in place, see Figure 5(d).

Alternatively, the outer lead metal deposition and formation may refer to depositing outer lead metal on the insulating layer of the source and drain metal and the insulating layer of the window away from the sensing region, respectively, see FIG. 5(e).

Alternatively, the outer lead metal insulation may mean forming an insulating layer on the outer lead metal and leaving a pad window in place with the outer circuit in place, see Figure 5(g).

Optionally, when the sensor uses AlGaN as the barrier layer 5, the sensing region formed by the foregoing process is subjected to a groove etching process to reduce the thickness of the sensing region 10 to a desired value for detection.

The sensing region 10 (eg, the gate region) is groove etched, termed "recessed gate", see Figure 5(f). The recess gate technique is only applicable to sensors in which AlGaN is used as an isolation layer (for example, barrier layer 5). However, when AlN is used as the barrier layer 5, since the barrier layer composed of AlN can be made thin in the epitaxial stage, the sensor can perform high-precision detection of the analyte to be detected without performing the concave gate.

Step 4: Functionalizing the sensing region 10 formed by the foregoing process to form a functionalized film 11 on the sensing region 10.

Alternatively, the functionalized film 11 coating of the sensing region 10 can be seen in Figure 5(h).

Step 5: The mesa structure having the ohmic contact source and drain metal 7 and the functionalized film 11 formed based on the foregoing process is subjected to metal interconnection insulation or encapsulation processing to obtain the sensor 1.

The sensor prepared by the above steps is shown in Fig. 6. The sensor includes a mesa 12, an insulating layer 8, an epitaxial layer 13, a substrate 2, and pads 14 connected to an external circuit.

The sensor prepared by the foregoing steps may also be at least one of the foregoing gallium nitride sensor or multi-sensor system.

Through a large number of experiments, the design and fabrication of the III-nitride-based HEMT sensor and the improved structure to improve the sensitivity of the sensor can be realized by using the technical scheme of the embodiment. The operation process is simple and reliable, and the obtained sensor has high sensitivity and wide detection range. small volume.

It is also to be understood that the terms "comprises" or "comprising" or "comprising" or any other variations are intended to encompass a non-exclusive inclusion, such that a process, method, article, Other elements not explicitly listed, or elements that are inherent to such a process, method, commodity, or equipment. An element defined by the phrase "comprising a ..." does not exclude the presence of additional equivalent elements in the process, method, item, or device including the element.

Industrial applicability

In the solution of the embodiment of the present disclosure, a sensor, a preparation method, and a multi-sensor system are proposed, which solve the problems of low sensitivity, small detection range, and poor portability of the related art.

Claims

A gallium nitride sensor comprising: a hetero semiconductor substrate, and a transistor of a group III nitride-based HEMT structure thereon; wherein

The source and drain metals of the transistor are disposed on the semiconductor of the top layer of the transistor, the gate surface has a functionalized film obtained by functionalization, and the exposed gate region between the source and the drain forms a sensing region. Detecting the concentration of the object to be detected in contact with the sensing area by detecting a change in current of the sensing area.
The sensor of claim 1 wherein said transistor comprises:

At least one group III nitride heterojunction, one side of which is GaN and the other side is other binary or ternary group III nitride different from GaN.
The sensor of claim 2 wherein said Group III nitride heterojunction comprises:

a buffer layer on the hetero semiconductor substrate, the buffer layer serving as a current channel and having a composition of GaN;

a barrier layer on the buffer layer, the composition of the barrier layer containing a multi-component group III nitride or ZnO and/or an intrinsic material; the buffer layer and the composition of the barrier layer interact, in the buffer layer and the barrier layer The interface forms a two-dimensional electron gas 2DEG; and,

An ohmic contact source and a drain metal on the barrier layer, a bare barrier layer between the ohmic contact source and the drain metal is a sensing region, and the functionalized film is coated on the sensing region Up; and,

The insulating layer is located on the ohmic contact source and drain metal, the 2DEG and the barrier layer, and on the side of the buffer layer near the barrier layer.
The sensor of claim 3, wherein the transistor further comprises:

a cover layer overlying the barrier layer, the composition of the cover layer being doped or using an intrinsic material to interact with the barrier layer;

An ohmic contact source and a drain metal formed on the cap layer; wherein a bare cap layer between the ohmic contact source and the drain metal is a sensing region;

The insulating layer is coated on the periphery of the cover layer.
A sensor according to any one of claims 3-4, wherein

a plurality of group III nitrides in the barrier layer, including any one of GaN, InN, AlN, AlGaN, InGaN, and AlInGaN;

and / or,

The insulating layer includes any one of an insulating oxide and an insulating high molecular polymer.
A sensor according to any one of claims 1 to 5, wherein

The substrate includes: an extrinsic semiconductor substrate and a group III nitride on the extrinsic semiconductor substrate, the extrinsic semiconductor including any one of silicon, silicon carbide, sapphire, and aluminum nitride .
The sensor according to any one of claims 1 to 6, wherein

The functionalized film includes any one or more of an oxide, a metal thin film, a nano material, a semiconductor, a nitride, an organic biomaterial, an inorganic material, and a polymer material.
A multi-sensor system comprising: at least two sensors according to any of claims 1-7, and a main control circuit;

Wherein the at least two sensors are connected in parallel, and two sensors connected in parallel are connected in series with the main control circuit;

The main control circuit is arranged to control and analyze the output signal of the sensor to realize the concentration detection of the object to be detected.
A method of preparing a sensor, comprising:

Forming a separate mesa structure on the epitaxial wafer by plasma etching;

Forming an ohmic contact source and a drain metal on top of the mesa structure based on the mesa structure, sequentially removing a surface oxide treatment, a metal precipitation and patterning treatment, and a high temperature annealing treatment;

An ohmic contact source and drain on top of the mesa structure, based on a mesa structure having an ohmic contact source and a drain metal formed on top, sequentially performing ohmic contact and metal deposition intercontacting processes, and interconnect metal deposition and forming processes Forming a sensing area between the polar metals;

Functionalizing treatment on the sensing area to form a functionalized film;

The sensor is obtained by performing metal interpenetrating insulation or encapsulation processing based on the ohmic contact source and drain metal and the mesa structure of the functionalized film.
The method of claim 9 further comprising:

When the sensor uses AlGaN as a barrier layer, the sensing region formed by the foregoing process is subjected to a groove etching process to reduce the thickness of the sensing region to a value required for detection.
A sensor comprising:

Substrate;

a transistor of a group III nitride-based HEMT structure on the substrate; wherein

The transistor includes:

Generating a heterojunction structure on the substrate;

Generating a source and drain metal layer on the heterojunction structure; wherein, between the source and the drain The area is the gate area;

a functionalized film obtained by functional processing on the gate region, wherein the analyte to be detected is in contact with the functionalized film, and the concentration of the analyte to be detected is detected by detecting a change in current of the gate region .
The sensor of claim 11 further comprising:

A cover layer disposed between the barrier layer and the metal layer.
The sensor of claim 11 wherein said heterojunction structure comprises:

At least one Group III nitride heterojunction comprising a buffer layer and a barrier layer.
The sensor according to claim 13, wherein

The buffer layer comprises a GaN material, the barrier layer comprising a binary, ternary or multi-component III nitride different from GaN;

The transistor further includes a two-dimensional electron gas 2DEG layer formed at an interface between the buffer layer and the barrier layer.
The sensor of any of claims 11-13, the transistor further comprising:

Provided on the metal layer, the buffer layer is adjacent to a surface of the two-dimensional electron gas, and an insulating layer on the exposed surface between the metal layer and the surface.
The sensor according to any one of claims 11 to 15, wherein

The composition of the barrier layer includes a multi-component group III nitride or zinc oxide Zn and/or a metal material, wherein the multi-component group III nitride includes any one of GaN, InN, AlN, AlGaN, InGaN, and AlInGaN.
A sensor according to any one of claims 11 to 16, wherein

The insulating layer includes any one of an insulating metal, an insulating oxide, and an insulating high molecular polymer.
A sensor according to any one of claims 11-17, wherein

The substrate includes an extrinsic semiconductor substrate and a group III nitride on the extrinsic semiconductor substrate.
The sensor of claim 18, wherein the extrinsic semiconductor comprises any one of silicon, silicon carbide, sapphire, and aluminum nitride.
A sensor according to any one of claims 12 to 19, wherein

The functionalized film includes any one or more of an oxide, a metal thin film, a nano material, a semiconductor, a nitride, an organic biomaterial, an inorganic material, and a polymer material.