III-nitride heterojunction tunneling field effect transistor-based biosensor and preparation method thereof

Abstract

The invention relates to a group III nitride heterojunction-based tunneling field effect transistor biosensor and a preparation method thereof, belongs to the technical field of biosensors, and solves the technical problems of limited tunneling area and small on-state current of an existing tunneling field effect transistor. The transistor biosensor comprises a drain region, an intrinsic region, an insertion layer, a source region, a gate dielectric layer, a metal gate, a drain electrode and a source electrode. The gate dielectric layer is located outside the intrinsic region and the insertion layer, the metal gate is located outside the gate dielectric layer, and the gate dielectric layer and the metal gate form a detection cavity. The preparation method comprises the following steps: preparing a sample; cleaning and drying the sample wafer; etching the table surface; ion implantation; depositing a gate dielectric layer; performing chemical vapor deposition on a passivation layer, and sputtering a metal gate; depositing a source electrode and a drain electrode; and etching the gate dielectric layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of biosensors, and in particular relates to a biosensor based on a III-group nitride heterojunction tunneling field effect transistor and a preparation method thereof. Background Art

[0002] MOSFET-based biosensors use the characteristic that gate capacitance changes after biomolecules enter the gate dielectric layer to identify biomolecules. However, as the scale of integrated circuits continues to expand, the characteristic size of MOSFET cannot continue to shrink at the original speed. Biosensors based on traditional MOSFETs also face severe challenges brought by the short channel effect. The subthreshold swing of TFET devices (tunneling field effect transistors) is generally smaller than that of MOSFET devices. Biosensors based on TFETs show good sensitivity and fast response time, which greatly improves the performance of biosensors. However, due to the problems of small on-state current and serious bipolar effect of TFET itself, the focus of research has begun to focus on improving device performance through structural optimization and material optimization. Summary of the invention

[0003] In order to solve the problems of limited tunneling area and small on-state current in existing tunneling field effect transistors, the present invention proposes a biosensor based on group III nitride heterojunction tunneling field effect transistors and a preparation method thereof.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A biosensor based on a III-group nitride heterojunction tunneling field effect transistor comprises a drain region, an intrinsic region, an insertion layer, a source region, a gate dielectric layer, a metal gate, a drain electrode, and a source electrode.

[0006] The drain electrode, drain region, intrinsic region, insertion layer, source region, and source electrode are arranged in sequence;

[0007] The gate dielectric layer is located outside the intrinsic region and the insertion layer, the metal gate is located outside the gate dielectric layer, the gate dielectric layer and the metal gate form a detection cavity, and the detection cavity is in a groove shape; the outside of the detection cavity is the metal gate, and the bottom and the inside are the gate dielectric layer;

[0008] There are heterojunctions between the source region and the insertion layer, and between the insertion layer and the intrinsic region;

[0009] The drain region, intrinsic region and source region are In x Ga 1-x N material;

[0010] The source region and the intrinsic region have the same doping type, while the drain region has opposite doping types to the source region and the intrinsic region.

[0011] In the above-mentioned III-nitride heterojunction tunneling field effect transistor biosensor, the drain region, the intrinsic region and the source region are all In 0.75 Ga 0.25 N material, the insertion layer is Al 0.1 In 0.9 N material, the gate dielectric layer is HfO 2 Materials: The metal gate is TiN material.

[0012] In the above-mentioned III-nitride heterojunction tunneling field effect transistor biosensor, the source region and the intrinsic region are P-type doped, and the drain region is N-type doped.

[0013] The above-mentioned III-nitride heterojunction tunneling field-effect transistor biosensor has a drain region with a thickness of 15nm to 20nm and a length of 8nm to 12nm; a thickness of the intrinsic region of 35nm to 55nm; a thickness of the insertion layer of 1.5nm to 3.5nm and a length of 8nm to 12nm; a thickness of the source region of 15nm to 20nm and a length of 8nm to 12nm; a length of the gate dielectric layer of 5nm to 10nm; a length of the metal gate of 0.5nm to 1.0nm and a work function of 4.5eV; a length of the detection cavity of 5nm to 10nm and a thickness of 20 to 35nm.

[0014] In the above-mentioned III-nitride heterojunction tunneling field effect transistor biosensor, the thickness of the drain region is 20 nm, the length is 10 nm, and the doping concentration of the drain region is 5×10 18 cm -3 The thickness of the intrinsic region is 50nm and the length is 10nm; the thickness of the insertion layer is 3.0nm and the length is 10nm; the thickness of the source region is 20nm and the length is 10nm. The doping concentration of the source region is 1×10 20 cm -3 ; The length of the gate dielectric layer is 11nm; the length of the detection cavity is 10nm and the thickness is 35nm; the length of the metal gate is 1.0nm and the work function is 4.5eV.

[0015] In the above-mentioned III-nitride heterojunction tunneling field effect transistor biosensor, the doping concentration of the source region is 5×10 19 cm -3 ~1×10 20 cm -3 , the doping concentration of the drain region is 5×10 18 cm -3 ~1×10 19 cm -3 ; The doping concentration of the intrinsic region is 5×10 16 cm -3 ~1×10 17 cm -3.

[0016] A method for preparing a group III nitride heterojunction tunneling field effect transistor biosensor comprises the following steps:

[0017] Step 1: Prepare the sample

[0018] A drain region, an intrinsic region, an insertion layer and a source region are grown in sequence on a substrate by using a metal organic vapor phase epitaxy method to form a sample.

[0019] Step 2: Clean and dry the sample

[0020] The sample is cleaned by soaking and rinsing to remove dirt on the surface of the sample. 2 The surface of the sample was blown dry with a gun and placed in N 2 Save in the environment for later use.

[0021] Step 3: Etching the mesa

[0022] The dried sample is placed in a plasma etcher and subjected to plasma etching to form an etched mesa sample.

[0023] Step 4, ion implantation

[0024] Ion implantation is performed on the source region, intrinsic region and drain region of the etched mesa sample respectively, the source region forms P-type doping, the intrinsic region and drain region form N-type doping, and annealing is performed to activate the implanted impurities.

[0025] Step 5: Deposit gate dielectric layer

[0026] A gate dielectric layer is deposited on the left and right surfaces of the intrinsic region and the insertion layer by using an atomic layer deposition (ALD) method.

[0027] Step 6, chemical vapor deposition of a passivation layer,

[0028] Plasma enhanced chemical vapor deposition (PECVD) is used to chemically deposit Si on the left and right sides of the drain region. 3 N 4 Passivation layer.

[0029] Step 7: Sputtering metal grid

[0030] A layer of TiN is formed on the surface of the sample by magnetron sputtering, and then ultrasonically cleaned to form a metal gate.

[0031] Step 8: Deposit source and drain electrodes

[0032] Using the evaporation method, metal is deposited on the top of the source region and annealed to form a source electrode; metal is deposited on the right side of the passivation layer and annealed to form a drain electrode.

[0033] Step 9: Etching the gate dielectric layer

[0034] The gate dielectric layer near the source region is etched by an etching method to form a nanometer detection cavity.

[0035] In the above method for preparing a group III nitride heterojunction tunneling field effect transistor biosensor, step S1 further comprises:

[0036] Using GaN / sapphire as substrate, In is grown on the substrate in sequence. 0.75 Ga 0.25 N drain region, In 0.75 Ga 0.25 N intrinsic region, Al 0.1 In 0.9 N insertion layer and In 0.75 Ga 0.25 N source region.

[0037] In the above method for preparing a group III nitride heterojunction tunneling field effect transistor biosensor, step 2 further comprises:

[0038] The soaking solution used for soaking is concentrated sulfuric acid-hydrogen peroxide solution, the volume ratio of concentrated sulfuric acid to hydrogen peroxide is 1:1, and the soaking time is 5 minutes. The rinsing process is: take out the sample from the soaking solution and rinse it repeatedly with deionized water. The drying process is: use N 2 The rinsed sample surface is blown dry with a gun; the dried sample is placed in N 2 Save in the environment for later use.

[0039] In the above method for preparing a group III nitride heterojunction tunneling field effect transistor biosensor, in step S5, the gate dielectric layer is a high-k dielectric HfO 2 film.

[0040] In step 7, ultrasonic cleaning is performed, the sample is completely immersed in the cleaning solution, the cleaning solution is an acetone solution, and the ultrasonic cleaning time is 10 minutes.

[0041] In the step 8, the deposited metal is nickel, the annealing temperature of the annealing treatment is 600° C., and the annealing time is 60 seconds.

[0042] The beneficial effects of the present invention are:

[0043] A biosensor based on a III-nitride heterojunction tunneling field-effect transistor is constructed by adding an Al2O3 junction between the source region and the intrinsic region. 0.1 In 0.9 N inserts a layer so that the In 0.75 Ga 0.25 N / A 0.1 In 0.9Under the influence of the polarization effect between N heterojunctions, the electric field of the tunnel junction is larger and the band bending is steeper, resulting in a decrease in the tunneling distance, an increase in the tunneling probability, and a significant improvement in the on-state current, thereby obtaining a better switching current ratio and a smaller subthreshold swing.

[0044] A biosensor based on a III-nitride heterojunction tunneling field-effect transistor is constructed by adding an Al2O3 junction between the source region and the intrinsic region. 0.1 In 0.9 The N insertion layer makes the depletion region of the PN junction narrower, the electric field of the tunnel junction larger, the band bending steeper, the tunneling probability increased, and a better switching current ratio and a smaller subthreshold swing are obtained, thereby achieving higher sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the structure of a double-gate tunneling field effect transistor based on the polarization effect;

[0046] Figure 2 It is a schematic diagram of the structure of a dielectric modulated III-nitride homojunction tunneling field effect transistor biosensor;

[0047] Figure 3 It is a schematic diagram of the structure of a biosensor based on a group III nitride heterojunction tunneling field effect transistor according to an embodiment of the present invention;

[0048] Figure 4 is a flow chart of the preparation method of an embodiment of the present invention;

[0049] Figure 5 is a comparison diagram of transfer characteristic curves of a non-polarized tunneling field effect transistor biosensor and an embodiment of the present invention;

[0050] Figure 6 It is a comparison diagram of the subthreshold sensitivity of the non-polarized tunneling field effect transistor biosensor and the embodiment of the present invention.

[0051] Figure numerals: 1. substrate, 2. drain region, 3. intrinsic region, 4. insertion layer, 5. source region, 6. gate dielectric layer, 7. passivation layer, 8. metal gate, 9. drain electrode, 10. source electrode, 11. detection cavity. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] Embodiment 1

[0054] The design idea of ​​a dielectric modulated III-nitride heterojunction tunneling field-effect transistor biosensor is as follows:

[0055] The crystal structure of III-nitride semiconductors does not have central symmetry and has a single symmetry axis, which leads to the separation of positive and negative charge centers in the unit cell and produces polar moments. Therefore, there is a spontaneous polarization effect inside III-nitride semiconductors. On the other hand, in III-nitride multilayer heterostructures, the lattice constant mismatch of different materials can cause crystal strain, resulting in piezoelectric polarization effects at the heterojunction interface. These polarization effects will generate polarized surface charges, thereby enhancing the interface electric field and increasing the tunneling probability. Compared with traditional silicon-based devices, In x Ga 1-x N materials can obtain suitable band gap and effective carrier mass under the condition of appropriate "In" component. At the same time, the material also has polarization effect. x Ga 1-x N devices can show superior performance. When the "In" component is equal to 0.75, In x Ga 1-x The band gap of N is similar to that of silicon. It can also suppress the off-state current of TFET to a certain extent, further improving the switching current ratio I ON / I OFF .

[0056] Based on the above concept, the design scheme provided by the present invention is:

[0057] A dielectric modulated III-nitride heterojunction tunneling field effect transistor biosensor comprises a source region 5, an insertion layer 4, an intrinsic region 3 and a drain region 2 arranged in sequence from left to right;

[0058] The upper and lower sides of the intrinsic region and the insertion layer are provided with a gate dielectric layer, a detection cavity and a metal gate in sequence from the inside to the outside;

[0059] An active electrode is disposed above the source region;

[0060] Both the source region and the intrinsic region are made of In 0.75 Ga 0.25 N material, thereby forming a heterojunction between the source region and the insertion layer, and between the insertion layer and the intrinsic region;

[0061] The doping types of the source region, the intrinsic region and the drain region are opposite, that is, the source region is P-type doped, and the intrinsic region and the drain region are N-type doped.

[0062] The metal gate is made of TiN, and the gate dielectric layer is made of HfO 2 preparation.

[0063] The length of the metal gate is 0.5-1nm;

[0064] The length of the gate dielectric layer is 6-11 nm;

[0065] The length of the passivation layer is 15-25nm;

[0066] The length of the detection cavity is 5-10nm;

[0067] The thickness of the detection cavity is 20-35nm;

[0068] The thickness of the source region is 15-20nm;

[0069] The thickness of the insertion layer is 1.5-3.5nm;

[0070] The thickness of the intrinsic region is 35-55nm;

[0071] The thickness of the drain region is 15-20nm;

[0072] The lengths of the source region, insertion layer, intrinsic region, and drain region are 8-12nm.

[0073] The doping concentration of the source region is 5×10 19 ~1×10 20 cm -3 , the doping concentration of the drain region is 5×10 18 ~1×10 19 cm -3 ; The doping concentration of the intrinsic region is 5×10 16 ~1×10 17 cm -3 .

[0074] The work function of the metal gate is 4.5 eV.

[0075] A method for preparing a dielectric modulated group III nitride heterojunction tunneling field effect transistor biosensor comprises the following steps:

[0076] Step 1: Grow In from bottom to top on the semiconductor substrate 0.75 Ga 0.25 N drain region, In 0.75 Ga 0.25 N intrinsic region, Al 0.1 In 0.9 N insertion layer and In 0.75 Ga 0.25 N source region, forming a test piece;

[0077] Step 2: Clean and dry the test piece obtained in step 1;

[0078] Step 3: Etching the mesa;

[0079] Step 4: ion implantation;

[0080] Step 5: depositing a gate dielectric layer;

[0081] Step 6: Chemical vapor deposition of a passivation layer;

[0082] Step 7: Sputtering gate metal;

[0083] Step 8: Deposit source and drain electrodes;

[0084] Step 9: Etching the gate dielectric layer.

[0085] Embodiment 2

[0086] Define the length along the x-axis and the thickness along the y-axis.

[0087] A dielectric modulated III-nitride heterojunction tunneling field effect transistor biosensor, such as Figure 3 As shown, including In 0.75 Ga 0.25 N drain region 2, In 0.75 Ga 0.25 N intrinsic region 3, Al 0.1 In 0.9 N insertion layer 4, In 0.75 Ga 0.25 N source region 5 , gate dielectric layer 6 , metal gate 8 , drain electrode 9 , source electrode 10 .

[0088] The components are set up as follows:

[0089] Al is set between the intrinsic region 3 and the source region 5 0.1 In 0.9 N insertion layer 4, source electrode 10 is arranged above the source region, drain electrode 9 is arranged on the right side of passivation layer 7, intrinsic region 3 and Al 0.1 In 0.9 A gate dielectric layer 6 and a metal gate 8 are sequentially disposed on the left and right sides of the N insertion layer 4 .

[0090] The source region 5 and drain region 2 are doped with P and N type seeds respectively. The doping concentration of the source region 5 is 5×10 19 -1×10 20 cm -3 , the doping concentration of drain region 2 is 5×10 18 -1×10 19 cm -3 , the doping concentration of intrinsic region 3 is 5×10 16 -1×10 17 cm -3 .

[0091] By setting In 0.75 Ga 0.25 N source region 5, Al 0.1 In 0.9 N insertion layer 4 and In 0.75 Ga 0.25 N intrinsic region 3, in In 0.75 Ga0.25 N source region 5 and Al 0.1 In 0.9 A heterojunction is formed between the N insertion layers 4. 0.1 In 0.9 N insertion layer 4 and In 0.75 Ga 0.25 N intrinsic regions 3 form a heterojunction, using the lattice constant difference between the two materials and the resulting polarization effect to promote tunneling probability and increase tunneling current; and + N + The depletion region of the junction is narrower, the electric field of the tunnel junction is larger, and the band bending is steeper, resulting in a decrease in the tunneling distance, an increase in the tunneling probability, and a significant improvement in the on-state current.

[0092] The metal gate 8 is made of TiN, the length of the metal gate 8 is 0.5-1 nm, and the work function of the metal gate 8 is 4.5 eV; the gate dielectric layer 6 is made of HfO 2 , the length of the gate dielectric layer 6 is 5-10nm, the thickness of the source region 5 is 15-20nm; Al 0.1 In 0.9 The thickness of the N insertion layer 4 is 1.5-3.5nm; the thickness of the intrinsic region 3 is 35-55nm; the thickness of the drain region 2 is 15-20nm, and the thickness of the source region 5 and Al 0.1 In 0.9 The lengths of the N insertion layer 4, the intrinsic region 3 and the drain region 2 are 8-12 nm; the length of the detection cavity 11 is 10 nm and the thickness is 35 nm.

[0093] In order to verify the effect of the transistor structure of the present invention, a dielectric modulated biosensor based on a III-nitride homojunction tunneling field effect transistor is set. The structure of the dielectric modulated biosensor based on a III-nitride homojunction tunneling field effect transistor is as follows: Figure 2 As shown, the thickness of the source region 5 is 20nm; the thickness of the intrinsic region 3 is 50nm; the thickness of the drain region 2 is 20nm; the length of the gate dielectric layer 6 is 1nm; the length of the gate dielectric layer 6 is 10nm; the length of the detection cavity 11 is 10nm and the thickness is 35nm; the length of the metal gate 8 is 1nm; the lengths of the source region 5, the intrinsic region 3, and the drain region 2 are 10nm, and the doping concentration of the source region 5 is 1×10 20 cm -3 , the doping concentration of intrinsic region 3 is 1×10 17 cm -3 The doping concentration of drain region 2 is 5×10 18 cm -3 The work function of the metal gate 8 is 4.5 eV. In the dielectric modulation-based III-nitride heterojunction tunneling field effect transistor biosensor of the present invention, the structure of the III-nitride heterojunction tunneling field effect transistor biosensor is as follows: Figure 3 As shown, the thickness of the drain region 2 is 20nm; the thickness of the intrinsic region 3 is 50nm; 0.1 In 0.9 The thickness of the N insertion layer 4 is 3 nm; the thickness of the source region 5 is 20 nm; the length of the gate dielectric layer 6 is 11 nm; the length of the detection cavity 11 is 10 nm and the thickness is 35 nm; the length of the metal gate 8 is 1 nm; the lengths of the source region 5, the insertion layer 4, the intrinsic region 3, and the drain region 2 are 10 nm; the doping concentration of the source region 5 is 1×10 20 cm -3 , the doping concentration of drain region 2 is 5×10 18 cm -3 , the work function of the metal gate 8 is 4.5 eV. The transfer curves of the above two structures are as follows: Figure 5 As shown (the horizontal axis is the gate voltage V GS , the unit is V; the vertical axis is the leakage current I DS , unit is A / μm), it can be seen from the figure that the band bending of the tunneling field effect transistor structure of the present invention is steeper, the on-state current is significantly improved, and it has a relatively high switching current ratio and a smaller subthreshold swing. Figure 6 The average subthreshold swing sensitivity comparison diagram of the above two structures is shown in Figure 2. Figure 6 It can be proved that the biosensor of the present invention has better sensitivity characteristics.

[0094] Figure 5 The transfer characteristic curve comparison between a dual-gate tunneling field effect transistor based on source region dielectric modulation and an embodiment of the present invention; Figure 5 In the figure, the horizontal axis is the gate voltage in V, and the vertical axis is the drain current in A / μm. The solid line is the transfer characteristic curve of the dual-gate TFET (DG-P-TFET) based on the polarization effect, and the dotted line is the transfer characteristic curve of the traditional non-polarized dual-gate TFET (DG-TFET). It can be seen that when the external drain voltage of the two is the same, the transfer characteristics of DG-P-TFET are significantly better than those of DG-TFET due to the polarization effect.

[0095] Figure 6 It is the changing trend of the subthreshold swing sensitivity of the dielectric modulated dual-gate TFET biosensor based on polarization effect and the dielectric modulated dual-gate TFET biosensor. Figure 6In the figure, the horizontal axis is the dielectric constant and the vertical axis is the subthreshold swing sensitivity. The square line is the variation trend of the subthreshold swing sensitivity of the dielectric modulated dual-gate TFET biosensor based on polarization effect (DG-P-DMTFET) with the change of dielectric constant; the circular line is the variation trend of the subthreshold swing sensitivity of the dielectric modulated dual-gate TFET biosensor (DG-DMTFET) with the change of dielectric constant. It can be seen that with the increase of dielectric constant, the subthreshold swing sensitivity of both gradually increases, but the overall subthreshold swing sensitivity of DG-P-DMTFET is higher than that of DG-DMTFET.

[0096] Based on the above structure, the present invention also proposes a method for preparing a dielectric modulated III-nitride heterojunction tunneling field effect transistor biosensor, by growing 15-20 nm In on a substrate 1. 0.75 Ga 0.25 N layer, as drain region 2, on which 35-55 nm In is grown 0.75 Ga 0.25 N layer, as the intrinsic region 3; 1.5 to 3.5 nm Al is further grown in the intrinsic region 3 0.1 In 0.9 N layer, as an insertion layer 4; in Al 0.1 In 0.9 15-20nm In layer is grown on the N layer 0.75 Ga 0.25 N layer, as the source region 5; P-type doping is formed in the source region 5 by ion implantation, N-type doping is formed in the intrinsic region 3 and the drain region 2, and annealing is performed to activate the impurities; a dielectric layer is deposited on the left and right surfaces of the insertion layer and the intrinsic region as a gate dielectric layer 6; Si is deposited on the left and right sides of the drain region 3 N 4 Passivation layer 7; a layer of TiN is sputtered on the surface of the sample to form a metal gate 8; using deposition and etching processes, metal electrodes are generated on the top layer of the source region 5 and the side of the passivation layer 7, serving as the source 10 and the drain 9 respectively; and then the gate dielectric layer 6 is etched by an etching process to form a detection cavity 11.

[0097] Specific:

[0098] Step 1: In is grown sequentially on GaN / sapphire substrate 1 by metal organic vapor phase epitaxy (MOVPE) 0.75 Ga 0.25 N drain region 2, In 0.75 Ga 0.25 N intrinsic region 3, Al 0.1 In 0.9 N insertion layer 4 and In 0.75 Ga 0.25 N source region 5, forming a test piece;

[0099] Step 2: Clean and dry the surface of the test piece in step 1

[0100] Place the sample in a prepared concentrated sulfuric acid-hydrogen peroxide solution (volume ratio is 1:1). Concentrated sulfuric acid will release a lot of heat when it meets hydrogen peroxide, which can effectively remove the dirt on the surface of the sample. The sample soaking time is about 5 minutes. After taking out the sample, rinse the sample repeatedly with a large amount of deionized water. Finally, use N 2 The surface of the sample was blown dry with a gun and placed in N 2 Save in environment

[0101] Step 3: Etching the Mesa

[0102] Place the sample into the plasma etcher and start plasma etching the sample

[0103] Step 4: Ion Implantation

[0104] Ion implantation is performed on the source region, intrinsic region, and drain region to form P-type doping and N-type doping, and then annealing is performed to activate the impurities;

[0105] Step 5: Deposition of gate dielectric layer

[0106] A layer of high-k dielectric HfO was deposited on the left and right surfaces of the intrinsic region and the insertion layer of the sample by atomic layer deposition (ALD). 2 The film serves as a gate dielectric layer;

[0107] Step 6: Chemical Vapor Deposition of Passivation Layer

[0108] Plasma enhanced chemical vapor deposition (PECVD) is used to chemically deposit Si on the left and right sides of the drain region. 3 N 4 Passivation layer;

[0109] Step 7: Sputtering the Gate Metal

[0110] After forming a layer of TiN metal on the surface of the sample by magnetron sputtering, the sample was completely immersed in an acetone solution and ultrasonically cleaned for 10 minutes to form a gate electrode;

[0111] Step 8: Deposit source and drain metal to form source and drain electrodes

[0112] A layer of metallic nickel is deposited on the sample and peeled off to form source and drain electrodes. The evaporation method is used to heat the metal atoms so that they can obtain enough energy to break free from the constraints of the metal surface and deposit on the surface of the sample. The sample is then annealed at a temperature of 600°C and a time of 60s.

[0113] Step 9: Etching the gate oxide layer

[0114] The gate oxide layer close to the source region and the gate metal layer is etched by an etching method to form a nano detection cavity.

Claims

1. A biosensor based on a III-nitride heterojunction tunneling field effect transistor, characterized in that: It comprises a drain region (2), an intrinsic region (3), an insertion layer (4), a source region (5), a gate dielectric layer (6), a metal gate (8), a drain electrode (9), and a source electrode (10); The drain electrode (9), the drain region (2), the intrinsic region (3), the insertion layer (4), the source region (5), and the source electrode (10) are arranged in sequence; The gate dielectric layer (6) is located outside the intrinsic region (3) and the insertion layer (4), the metal gate (8) is located outside the gate dielectric layer (6), the gate dielectric layer (6) and the metal gate (8) form a detection cavity (11), and the detection cavity (11) is in the shape of a groove; the outside of the detection cavity (11) is the metal gate (8), and the bottom and the inside are the gate dielectric layer (6); There are heterojunctions between the source region (5) and the insertion layer (4), and between the insertion layer (4) and the intrinsic region (3); The drain region (2), the intrinsic region (3) and the source region (5) are In x Ga 1-x N material; The doping types of the drain region (2) and the intrinsic region (3) are opposite, and the doping types of the source region (5) and the intrinsic region (3) are the same.

2. The III-nitride heterojunction tunneling field effect transistor biosensor according to claim 1, characterized in that: The drain region (2), the intrinsic region (3) and the source region (5) are all In 0.75 Ga 0.25 N material, the insertion layer (4) is Al 0.1 In 0.9 N material, the gate dielectric layer (6) is HfO2 material, and the metal gate (8) is TiN material.

3. The III-nitride heterojunction tunneling field effect transistor biosensor according to claim 1, characterized in that: The source region (5) and the intrinsic region (3) are P-type doped, and the drain region (2) is N-type doped.

4. The III-nitride heterojunction tunneling field effect transistor biosensor according to claim 1, characterized in that: The drain region (2) has a thickness of 15nm-20nm and a length of 8nm-12nm; the intrinsic region (3) has a thickness of 35nm-55nm and a length of 8nm-12nm; the insertion layer (4) has a thickness of 1.5nm-3.5nm and a length of 8nm-12nm; the source region (5) has a thickness of 15nm-20nm and a length of 8nm-12nm; the gate dielectric layer (6) has a length of 6nm-11nm; the metal gate (8) has a length of 0.5nm-1.0nm and a work function of 4.5eV; the detection cavity (11) has a length of 5nm-10nm and a thickness of 20-35nm.

5. The III-nitride heterojunction tunneling field effect transistor biosensor according to claim 1, characterized in that: The thickness of the drain region (2) is 20 nm, the length is 10 nm, and the doping concentration of the drain region (2) is 5×10 18 cm -3 ; The thickness of the intrinsic region (3) is 50 nm, the length is 10 nm, and the doping concentration of the intrinsic region (3) is 1×10 17 cm -3 The thickness of the insertion layer (4) is 3.0 nm and the length is 10 nm; the thickness of the source region (5) is 20 nm and the length is 10 nm. The doping concentration of the source region (5) is 1×10 20 cm -3 ; The length of the gate dielectric layer (6) is 11 nm; The length of the metal gate (8) is 1.0 nm; The length of the detection cavity (11) is 10 nm and the thickness is 35 nm.

6. The III-nitride heterojunction tunneling field effect transistor biosensor according to claim 1, characterized in that: The doping concentration of the source region (5) is 5×10 19 cm -3 ~1×10 20 cm -3 , the doping concentration of the drain region (2) is 5×10 18 cm -3 ~1×10 19 cm -3 ; The doping concentration of the intrinsic region (3) is 5×10 16 cm -3 ~1×10 17 cm -3 .

7. A method for preparing a group III nitride heterojunction tunneling field effect transistor biosensor according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1, prepare the sample: A drain region (2), an intrinsic region (3), an insertion layer (4) and a source region (5) are sequentially grown on a substrate (1) by using a metal organic vapor phase epitaxy method to form a sample; Step 2: Clean and dry the sample: The sample is cleaned by soaking and rinsing to remove dirt on the surface of the sample; the surface of the sample is blown dry and stored in a N2 environment for later use; Step 3, etching the mesa: Put the dried sample into a plasma etcher and perform plasma etching to form an etched mesa sample; Step 4, ion implantation: Ion implantation is performed on the source region (5), the intrinsic region (3) and the drain region (2) of the etched mesa sample respectively, the source region (5) is P-type doped, the intrinsic region (3) and the drain region (2) are N-type doped, and annealing is performed to activate the implanted impurities; Step 5, depositing a gate dielectric layer (6): A gate dielectric layer (6) is deposited on the left and right surfaces of the intrinsic region (3) and the insertion layer (4) by using an atomic layer deposition (ALD) method; Step 6, chemical vapor deposition of a passivation layer (7): Using plasma enhanced chemical vapor deposition, chemical vapor deposition of Si3N4 passivation layer (7) is performed on the left and right sides of the drain region (2); Step 7, sputtering metal grid (8): Forming a layer of TiN on the surface of the sample by magnetron sputtering, and ultrasonic cleaning to form a metal gate (8); Step 8, depositing source electrode (10) and drain electrode (9): Using an evaporation method, metal is deposited on the top of the source region (5), and annealed to form a source electrode (10); metal is deposited on the right side of the passivation layer (7), and annealed to form a drain electrode (9); Step 9, etching the gate dielectric layer (6): An etching method is adopted to etch the gate dielectric layer (6) close to the source region (5) to form a nanometer detection cavity (11).

8. The method for preparing a biosensor based on a group III nitride heterojunction tunneling field effect transistor according to claim 7, characterized in that: The step 1 further comprises: Using GaN / sapphire as substrate (1), In 0.75 Ga 0.25 N drain region (2), In 0.75 Ga 0.25 N intrinsic region (3), Al 0.1 In 0.9 N insertion layer (4) and In 0.75 Ga 0.25 N source region (5).

9. The method for preparing a biosensor based on a III-nitride heterojunction tunneling field effect transistor according to claim 7, characterized in that: The step 2 further comprises: The immersion solution used was concentrated sulfuric acid-hydrogen peroxide solution, the volume ratio of concentrated sulfuric acid to hydrogen peroxide was 1:1, and the immersion time was 5 minutes; the rinsing process was: taking out the sample from the immersion solution and rinsing it repeatedly with deionized water; the drying process was: using a N2 gun to blow dry the surface of the rinsed sample; and the dried sample was placed in a N2 environment for storage.

10. The method for preparing a biosensor based on a group III nitride heterojunction tunneling field effect transistor according to claim 7, characterized in that: In the step 5, the gate dielectric layer (6) is a high-k dielectric HfO2 thin film; In step 7, ultrasonic cleaning is performed, the sample is completely immersed in the cleaning solution, the cleaning solution is an acetone solution, and the ultrasonic cleaning time is 10 minutes; In the step 8, the deposited metal is nickel; the annealing temperature of the annealing treatment is 600° C., and the annealing time is 60 seconds.

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