A biosensor based on a parallel tunneling junction vertical tunneling field effect transistor and a preparation method thereof

Abstract

The application relates to the technical field of semiconductor devices, and discloses a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor and a preparation method thereof. The sensor comprises a stepped drain region, drain contacts arranged on the two sides of the drain region, a stepped channel layer arranged on the top of the drain region, source regions arranged on the two sides of the channel layer, source contacts arranged on the top of each source region, a groove arranged on the top layer of the channel layer, a gate dielectric layer arranged in the groove, a gate metal arranged on the upper surface of the gate dielectric layer at the bottom of the groove, and a cavity formed between the gate metal and the gate dielectric layer, which is a biomolecule detection cavity. The preparation method comprises the following steps: etching the drain region and the channel layer to obtain a target shape and a groove structure, embedding the source region and an oxide layer, etching part of the oxide layer and embedding the gate metal, etching the oxide layer on the two sides of the gate metal and growing the gate dielectric layer, forming the biomolecule detection cavity, and metalizing part positions of the source region and the drain region to obtain a final structure. The device current and the sensitivity of biomolecule detection are improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, specifically to a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor and its fabrication method, for detecting unknown biomolecules. Background Technology

[0002] Biosensors can detect, record, and quantify physiological parameters and biochemical processes in the body, significantly impacting disease diagnosis and health assessment. Field-effect transistor (FET) biosensors are an emerging biosensing technology that effectively addresses shortcomings such as high requirements for equipment and operation, high cost of markers, and difficulty in fabrication. FET-based biosensors convert biological signals into electrical signals through biometric recognition, offering fast response, high detection accuracy, and low cost, thus possessing very broad research prospects. However, with the continuous development of integrated circuits and the miniaturization of device dimensions, the common short-channel effect of MOSFETs is becoming increasingly severe. Due to the self-carrier thermal injection working principle, the subthreshold swing is difficult to escape the 60mV / dec limit at room temperature, which also hinders high-speed detection.

[0003] Iman Chahardah Cherik et al. disclosed a scheme called "Dielectric Modulated Doping-Less Tunnel Field-Effect Transistor, a Novel Biosensor Based on Cladding Layer Concept" (Iman Chahardah Cherik.Dielectric Modulated Doping-Less Tunnel Field-Effect Transistor, a Novel Biosensor Based on Cladding Layer Concept[J].IEEE SENSORS JOURNAL, 2022, 22(11): 10308-10314). This scheme utilizes the concept of a capping layer to introduce holes in the Ge source region, and two nanocavities for filling biomolecules are etched into the capping layer. This structure can operate at low voltages, but its sensitivity is not high. Vandana Devi Wangkheirakpam et al. disclosed a "N +Pocket DopedVertical TFET Based Dielectric-Modulated Biosensor Considering Non-IdealHybridization Issue: A Simulation Study" plan (Vandana Devi Wangkheirakpam.N + Pocket Doped Vertical TFET Based Dielectric-Modulated Biosensor Considering Non-Ideal Hybridization Issue: A Simulation Study [J]. IEEE TRANSACTIONS ON NANOTECHNOLOGY, 2020, 19: 156-162. A biosensor with an embedded nanocavity based on an N+ pocket-doped vertical TFET (VTFET) was proposed. This device has a nanocavity around HfO2, which enhances the capture area of ​​the biosensor and has a high conduction current, but the sensitivity is not high when detecting charged molecules. Patent application CN112736142A discloses a biosensor based on a nanosheet stacked field-effect transistor and its fabrication method. Three vertically stacked nanosheets form a channel, and a nanocavity is etched on the side near the source end. This structure overcomes the short-channel effect, but the disadvantages are high power consumption and large subthreshold swing. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor and its fabrication method. The gate metal is placed in a trench to form a trench gate. The left and right sides of the trench gate are the source region and the channel layer. The channel layer wraps around the source region to form a parallel tunneling junction, which has the characteristics of high reliability, high sensitivity and faster detection speed.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes a drain region 3 with two double-layer stepped shapes on both sides. Drain contacts 8 are provided on the upper surface of the bottom step on both sides of the drain region 3. A channel layer 2 with two double-layer stepped shapes on both sides is provided on the top step surface of the drain region 3. A source region 1 is provided at the steps on both sides of the channel layer 2. The source region 1 is simultaneously attached to the upper surface of the bottom layer and the side of the top layer of the channel layer 2. A source contact 7 is provided on the upper surface of each source region 1. A trench is formed on the top layer of the channel layer 2. A gate dielectric layer 4 is provided in the trench. A gate metal 5 is provided on the upper surface of the gate dielectric layer 4 at the bottom of the trench. The gate metal 5 and the gate dielectric layers 4 on both sides of the trench form a cavity, which serves as a biomolecule detection cavity 6.

[0007] The bottom layer of the drain region 3 has a length of 160-170 nm and a thickness of 8-12 nm, while the top layer has a length of 140-150 nm and a thickness of 5-10 nm.

[0008] Each of the drain contacts 8 has a length of 4–5 nm, and is less than The thickness is 1-2 nm;

[0009] The bottom layer of the channel layer 2 has the same length as the top layer of the drain region 3, and the thickness is 40-45 nm. The top layer lengths of the channel layer 2 on both sides of the trench are 3-8 nm, the thicknesses are 30-35 nm, the trench depths are 45-50 nm, and the widths are 26-28 nm.

[0010] Each source region 1 has a length of 1 The thickness is the top layer thickness of trench layer 2;

[0011] Each of the aforementioned source contacts 7 has a length of 45–48 nm, which is less than the length of the source region 1, and a thickness of 1–2 nm;

[0012] The gate dielectric layer 4 is adapted to the trench size. The bottom length of the gate dielectric layer 4 is the same as the trench width, the layer thickness is 1-3nm, the length of both sides is 1-2nm, and the thickness is the same as the trench depth.

[0013] The gate metal 5 has a length of 16-20 nm and a thickness of the trench depth minus the bottom thickness of the gate dielectric layer 4 in nm.

[0014] The depth of the biomolecule detection cavity 6 is the same as the thickness of the gate metal 5, and its width is...

[0015]

[0016] Source region 1 is heavily p-type doped with a doping concentration of 5 × 10⁻⁶. 19 ~5×10 20 cm -3 ;

[0017] Channel layer 2 is lightly doped with N-type material, with a doping concentration of 1×10⁻⁶. 15 ~5×10 17 cm -3 ;

[0018] Drain region 3 is heavily N-type doped with a doping concentration of 5 × 10⁻⁶. 18 ~1×10 19 cm -3 .

[0019] The source region 1 is a III-V group material;

[0020] Both the channel layer 2 and the drain region 3 are made of silicon material;

[0021] The gate dielectric layer 4 is made of an oxide material;

[0022] Gate metal 5, source contact 7, and drain contact 8 are all made of metal.

[0023] The group III-V materials are germanium silicon, indium arsenide, or gallium arsenide;

[0024] The oxide material is aluminum oxide, silicon dioxide, or hafnium dioxide;

[0025] The metal material is hafnium, aluminum, or gallium.

[0026] A method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes the following steps:

[0027] Step 1: Etch both sides of the rectangular heavily doped silicon material to obtain a drain region 3 with double-layer stepped shape on both sides. Lightly doped silicon material is epitaxially grown on the top of the drain region 3 to form a silicon epitaxial wafer.

[0028] Step 2: Cover the silicon epitaxial wafer grown in Step 1 with a mask, and use photolithography to open an etching window. Reactive ions simultaneously etch the middle and both sides of the silicon epitaxial wafer, forming a trench structure in the middle and a double-layer stepped structure on both sides, reserving space for the subsequent growth of the gate dielectric layer 4, gate metal 5 and source region 1, and preparing the channel layer 2.

[0029] Step 3: Molecular beam epitaxy (MBE) is used to embed a group III-V material into the double-layer stepped structure region etched on top of the channel layer 2 prepared in step 2, and B ion implantation is performed to form source region 1;

[0030] Step 4: Use chemical vapor deposition to fill the trenches formed by etching in step 2 with oxide material. Use an isotropic process to avoid the formation of voids in the oxide material. Planarize the surface of the oxide material to keep the oxide material level with the top of the trench layer 2, in preparation for subsequent patterning.

[0031] Step 5: Use reactive ion etching (Etch) to form the growth sites of the gate metal 5 using the oxide material deposited in step 4.

[0032] Step 6: Deposit metal material into the growth location of the gate metal 5 etched in Step 5, and planarize the metal material to serve as the gate metal 5.

[0033] Step 7: Selective etching is used to etch the oxide material on both sides of the gate metal 5 deposited in step 6 to form nanocavities on both sides of the gate metal 5.

[0034] Step 8: Using chemical vapor deposition, oxide material is grown on the sidewall of the channel layer 2 within the nanocavity formed in step 7. Together with the oxide material etched in step 5, it forms the gate dielectric layer 4, leaving a nanocavity as the biomolecule detection cavity 6.

[0035] Step 9: Metallize the upper surface of source region 1 to form source contact 7, and metallize the upper surface of the bottom step of drain region 3 to form drain contact 8, thus fabricating the final structure, i.e., fabricating a biosensor based on parallel tunneling junction vertical tunneling field-effect transistor.

[0036] The drain region 3 mentioned in step 1 is heavily N-type doped with a doping concentration of 5 × 10⁻⁶. 18 ~1×10 19 cm -3 ;

[0037] The channel layer 2 mentioned in step 2 is lightly doped N-type with a doping concentration of 1×10⁻⁶. 15 ~5×10 17 cm -3 ;

[0038] In step 2, source region 1 is heavily p-type doped with a doping concentration of 5 × 10⁻⁶. 19 ~5×10 20 cm -3 .

[0039] The group III-V materials are germanium silicon, indium arsenide, or gallium arsenide;

[0040] The oxide material is aluminum oxide, silicon dioxide, or hafnium dioxide;

[0041] Both the source contact 7 and the drain contact 8 are made of metallic materials;

[0042] The metal material is hafnium, aluminum, or gallium.

[0043] In step 1, the bottom layer of the drain region 3 has a length of 160-170 nm and a thickness of 8-12 nm, while the top layer has a length of 140-150 nm and a thickness of 5-10 nm.

[0044] In step 2, the bottom layer of the channel layer 2 has the same length as the top layer of the drain region 3, and the thickness is 40-45 nm. The top layer has a length of 3-8 nm and a thickness of 30-35 nm. The trench structure has a depth of 45-50 nm and a width of 26-28 nm.

[0045] In step 3, the length of source region 1 is The thickness is the same as the top layer thickness of trench layer 2;

[0046] The gate metal 5 deposited in step 6 has a length of 16-20 nm and a thickness of trench depth minus the bottom thickness of gate dielectric layer 4 in nm.

[0047] The gate dielectric layer 4 formed in step 8 is adapted to the trench size. The bottom length of the gate dielectric layer 4 is the same as the trench width, the layer thickness is 1-3 nm, and the lengths on both sides are 1-2 nm, with the thickness being the same as the trench depth. The depth of the biomolecule detection cavity 6 is the same as the thickness of the gate metal 5, and the width is...

[0048]

[0049] The source contact 7 obtained by metallization in step 9 has a length of 45–48 nm, which is less than the length of the source region 1, and a thickness of 1–2 nm; the drain contact 8 has a length of 4–5 nm, which is less than... The thickness is 1-2 nm.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] 1. This invention introduces a dual-source region 1 and extends the channel layer 2 to the top of the source region 1, so that the channel layer 2 wraps around both sides of the source region 1, thereby introducing transverse and longitudinal tunneling. At the same time, it increases the contact area between the source region 1 and the channel layer 2, thereby increasing the tunneling surface area and increasing the tunneling probability. When biomolecules enter the biomolecule detection cavity 6, it increases the band tunneling generation rate at the junction of the source region 1 and the channel layer 2, which can effectively make up for the low conduction current defect of the traditional horizontal pin structure. At the same time, the effective coupling between the source region 1 and the channel layer 2 is enhanced, which increases the turn-on current under different biomolecule dielectric constants K.

[0052] 2. In this invention, the gate metal 5 is disposed within a trench to form a trench gate. While maintaining the number of biomolecule detection cavities, this increases the switching speed of the device and improves its reliability. Two biomolecule detection cavities 6 are established on both sides of the gate metal 5, allowing the biomolecule detection cavities 6 to effectively control the conduction of the two parallel tunnel junctions, thereby enhancing the drain current of the sensor structure.

[0053] 3. The biomolecule detection cavity 6 of this invention covers the entire tunneling region. The upper cavity modulates longitudinal tunneling, and the lower cavity modulates transverse tunneling, making the modulation effect of different biomolecules on the device channel more obvious and improving the sensing performance of the device. The biomolecule detection cavity 6 is located in the vertical direction, allowing biomolecules to enter the biomolecule detection cavity 6 more effectively.

[0054] 4. This invention is based on a vertically structured tunneling field-effect transistor. Compared to complex structures like core-shell nanotubes, it eliminates the need for multiple etching and ion implantation processes, simplifying the fabrication process and reducing costs. The vertical structure also facilitates large-scale integration.

[0055] In summary, the biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor (PTJ) proposed in this invention has a vertical structure, which is more conducive to large-scale integration. Simultaneously, the biomolecule detection cavities 6 are also vertically distributed. Under the influence of gravity, biomolecules can more easily enter the cavities for analysis. Extending the channel layer 2 to wrap around the source region 1 increases the contact area between the source region 1 and the channel layer 2, thereby increasing the tunneling area. Placing the gate metal 5 in the trench to form a trench gate increases the switching speed of the device and improves its reliability while ensuring the number of biomolecule detection cavities 6. Two channel layers 2 are established on both sides of the gate metal 5. The parallel conduction of the two channel layers 2 enhances the drain current. The biosensor based on the parallel tunneling junction vertical tunneling field-effect transistor effectively improves sensitivity and stability. Furthermore, there is still significant room for improvement and potential in other performance aspects. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the biosensor structure of the present invention.

[0057] Figure 2 This is a process flow diagram of the biosensor of the present invention.

[0058] Figure 3 This is a simulation characteristic curve of the computer-aided design software in Embodiment 1 of the present invention.

[0059] Figure 4 This is a comparison chart of the sensitivity of biomolecules with different dielectric constants between Embodiment 1 of the present invention and a traditional vertical TFET-based biosensor.

[0060] Figure 5 This is a simulation characteristic curve of the computer-aided design software in Embodiment 2 of the present invention.

[0061] Figure 6 This is a comparison chart of the sensitivity of biomolecules with different dielectric constants between Embodiment 2 of the present invention and a traditional vertical TFET-based biosensor.

[0062] Figure 7 This is a simulation characteristic curve of the computer-aided design software in Embodiment 3 of the present invention.

[0063] Figure 8 This is a comparison chart of the sensitivity of biomolecules with different dielectric constants between Embodiment 3 of the present invention and a traditional vertical TFET-based biosensor.

[0064] Figure 9 This is a simulation characteristic curve of the computer-aided design software in Embodiment 4 of the present invention.

[0065] Figure 10 This is a comparison chart of the sensitivity of biomolecules with different dielectric constants between Embodiment 4 of the present invention and a traditional vertical TFET-based biosensor.

[0066] In the diagram, the markings are: 1 for the source region, 2 for the channel layer, 3 for the drain region, 4 for the gate dielectric layer, 5 for the gate metal, 6 for the biomolecular detection cavity, 7 for the source contact, and 8 for the drain contact. Detailed Implementation

[0067] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0068] Example 1

[0069] like Figure 1 A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes a drain region 3 with two double-layer stepped shapes on both sides. Drain contacts 8 are provided on the upper surface of the bottom step on both sides of the drain region 3. A channel layer 2 with two double-layer stepped shapes on both sides is provided on the top step surface of the drain region 3. A source region 1 is provided at the steps on both sides of the channel layer 2. The source region 1 is in contact with both the upper surface of the bottom layer and the side of the top layer of the channel layer 2. A source contact 7 is provided on the upper surface of each source region 1. A trench is formed on the top layer of the channel layer 2. A gate dielectric layer 4 is provided in the trench. A gate metal 5 is provided on the upper surface of the gate dielectric layer 4 at the bottom of the trench. The gate metal 5 and the gate dielectric layers 4 on both sides of the trench form a cavity, which serves as a biomolecule detection cavity 6.

[0070] like Figure 2 A method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes the following steps:

[0071] Step 1: For an N-type heavy doping concentration of 1×10⁻⁶ nm with a length of 160 nm and a thickness of 20 nm... 19 cm -3 Etching was performed on both sides of a rectangular silicon material, with each etched region being 5 nm long and 10 nm deep, resulting in a double-layered stepped drain region 3 on both sides. A lightly doped silicon material with a length of 150 nm and a thickness of 70 nm was epitaxially grown at the top of drain region 3, with a doping concentration of 5 × 10⁻⁶. 15 cm-3 This forms a silicon epitaxial wafer;

[0072] Step 2: Cover the silicon epitaxial wafer grown in Step 1 with a mask, and use photolithography to open etching windows. Simultaneously etch the middle and both sides of the silicon epitaxial wafer with reactive ions. The width of the middle etched area is 26nm and the depth is 45nm, forming a trench structure. The length of the etched areas on both sides is 56nm and the depth is 30nm, forming a double-layer stepped structure. This reserves space for the subsequent growth of the gate dielectric layer 4, gate metal 5 and source region 1, and prepares the channel layer 2.

[0073] Step 3: Using molecular beam epitaxy (MBE), gallium arsenide with a length of 56 nm and a thickness of 30 nm is embedded in the double-layer stepped structure region etched on top of the channel layer 2 prepared in Step 2, and boron ion implantation is performed to form source region 1 with a doping concentration of 1 × 10⁻⁶. 20 cm -3 ;

[0074] Step 4: Use chemical vapor deposition to fill the trenches formed by etching in step 2 with hafnium oxide. Use an isotropic process to avoid the formation of voids in the oxide material. Planarize the surface of the oxide material to keep the oxide material level with the top of the trench layer 2, in preparation for subsequent patterning.

[0075] Step 5: Use reactive ion etching (Etch) to etch the hafnium oxide deposited in step 4. The etched area is 16 nm long and 43 nm deep, forming the growth site of the gate metal 5.

[0076] Step 6: Deposit gallium into the growth site of the gate metal 5 etched in step 5, and planarize the gallium to serve as the gate metal 5.

[0077] Step 7: Selective etching is used to etch the hafnium oxide on both sides of the gate metal 5 deposited in step 6 to form nanocavities on both sides of the gate metal 5.

[0078] Step 8: Hafnium oxide is grown on the sidewall of the channel layer 2 in the nanocavity formed in step 7 using chemical vapor deposition. Together with the hafnium oxide etched in step 5, it forms the gate dielectric layer 4, leaving a nanocavity with a length of 3nm and a depth of 43nm as the biomolecule detection cavity 6.

[0079] Step 9: Metallize the upper surface of source region 1 with gallium material to form a source contact 7 with a length of 45 nm and a thickness of 1 nm. Metallize the upper surface of the bottom step of drain region 3 with gallium material to form a drain contact 8 with a length of 4 nm and a thickness of 1 nm. The final structure is thus formed, i.e., a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor is formed.

[0080] Depend on Figure 3 It is known that increasing the dielectric constant allows the device to have a larger saturation current at the same gate voltage. Compared with traditional TFET biosensors, it exhibits a higher on-state current. By comparing the transfer characteristics, Example 1 has a lower on-state current of 1.42 × 10⁻⁶ when K = 1. -14 A / μm, exhibiting a high on-state current of 2.64 × 10⁻⁶ at K = 10. - 7 A / μm. Meanwhile, by Figure 4 It can be seen that Example 1 has a higher on-current sensitivity compared to the conventional TFET biosensor under different dielectric constants. At K=12, the on-current sensitivity of the conventional TFET biosensor is 1.27×10⁻⁶. 5 The conduction current sensitivity of Example 1 is 1.86 × 10⁻⁶. 7 This is 146 times that of traditional TFET biosensors. This indicates that Example 1 has a greater advantage in terms of sensitivity.

[0081] Example 2

[0082] like Figure 1 A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes a drain region 3 with two double-layer stepped shapes on both sides. Drain contacts 8 are provided on the upper surface of the bottom step on both sides of the drain region 3. A channel layer 2 with two double-layer stepped shapes on both sides is provided on the top step surface of the drain region 3. A source region 1 is provided at the steps on both sides of the channel layer 2. The source region 1 is in contact with both the upper surface of the bottom layer and the side of the top layer of the channel layer 2. A source contact 7 is provided on the upper surface of each source region 1. A trench is formed on the top layer of the channel layer 2. A gate dielectric layer 4 is provided in the trench. A gate metal 5 is provided on the upper surface of the gate dielectric layer 4 at the bottom of the trench. The gate metal 5 and the gate dielectric layers 4 on both sides of the trench form a cavity, which serves as a biomolecule detection cavity 6.

[0083] like Figure 2 A method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes the following steps:

[0084] Step 1: For an N-type heavy doping concentration of 1×10⁻⁶ nm with a length of 170 nm and a thickness of 15 nm... 19 cm -3 Etching was performed on both sides of a rectangular silicon material, with each etched region being 10 nm long and 5 nm deep, resulting in a double-layered stepped drain region 3 on both sides. A lightly doped silicon material with a length of 150 nm and a thickness of 75 nm was epitaxially grown at the top of drain region 3, with a doping concentration of 1 × 10⁻⁶. 17 cm -3 This forms a silicon epitaxial wafer;

[0085] Step 2: Cover the silicon epitaxial wafer grown in Step 1 with a mask, and use photolithography to open etching windows. Simultaneously etch the middle and both sides of the silicon epitaxial wafer with reactive ions. The width of the middle etched area is 28nm and the depth is 50nm, forming a trench structure. The length of the etched areas on both sides is 53nm and the depth is 35nm, forming a double-layer stepped structure. This reserves space for the subsequent growth of the gate dielectric layer 4, gate metal 5 and source region 1, and prepares the channel layer 2.

[0086] Step 3: Using molecular beam epitaxy (MBE), gallium arsenide with a length of 53 nm and a thickness of 35 nm is embedded in the double-layer stepped structure region etched on top of the channel layer 2 prepared in Step 2, and boron ion implantation is performed to form source region 1 with a doping concentration of 1 × 10⁻⁶. 20 cm -3 ;

[0087] Step 4: Use chemical vapor deposition to fill the trenches formed by etching in step 2 with hafnium oxide. Use an isotropic process to avoid the formation of voids in the oxide material. Planarize the surface of the oxide material to keep the oxide material level with the top of the trench layer 2, in preparation for subsequent patterning.

[0088] Step 5: Use reactive ion etching (Etch) to etch the hafnium oxide deposited in step 4. The etched area is 20 nm long and 48 nm deep, forming the growth site of the gate metal 5.

[0089] Step 6: Deposit gallium into the growth site of the gate metal 5 etched in step 5, and planarize the gallium to serve as the gate metal 5.

[0090] Step 7: Selective etching is used to etch the hafnium oxide on both sides of the gate metal 5 deposited in step 6 to form nanocavities on both sides of the gate metal 5.

[0091] Step 8: Hafnium oxide is grown on the sidewall of the channel layer 2 in the nanocavity formed in step 7 using chemical vapor deposition. Together with the hafnium oxide etched in step 5, it forms the gate dielectric layer 4, leaving a nanocavity with a length of 3nm and a depth of 48nm as the biomolecule detection cavity 6.

[0092] Step 9: Metallize the upper surface of source region 1 with gallium material to form a source contact 7 with a length of 48 nm and a thickness of 1 nm. Metallize the upper surface of the bottom step of drain region 3 with gallium material to form a drain contact 8 with a length of 4 nm and a thickness of 1 nm. The final structure is thus formed, i.e., a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor is formed.

[0093] Depend on Figure 5It is known that increasing the dielectric constant allows the device to have a larger saturation current at the same gate voltage. Compared with traditional TFET biosensors, it exhibits a higher on-state current. By comparing the transfer characteristics, Example 2 shows a lower on-state current of 1.73 × 10⁻⁶ at K = 1. -16 A / μm, exhibiting a high on-state current of 4.60 × 10⁻⁶ at K = 10. - 9 A / μm. Meanwhile, by Figure 6 It can be seen that when K=12, the on-current sensitivity of the traditional TFET biosensor is 1.27×10⁻⁶. 5 The conduction current sensitivity of Example 2 is 2.69 × 10⁻⁶. 7 This is 212 times that of a traditional TFET biosensor. This indicates that Example 2 has a greater advantage in terms of sensitivity.

[0094] Example 3

[0095] like Figure 1 A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes a drain region 3 with two double-layer stepped shapes on both sides. Drain contacts 8 are provided on the upper surface of the bottom step on both sides of the drain region 3. A channel layer 2 with two double-layer stepped shapes on both sides is provided on the top step surface of the drain region 3. A source region 1 is provided at the steps on both sides of the channel layer 2. The source region 1 is in contact with both the upper surface of the bottom layer and the side of the top layer of the channel layer 2. A source contact 7 is provided on the upper surface of each source region 1. A trench is formed on the top layer of the channel layer 2. A gate dielectric layer 4 is provided in the trench. A gate metal 5 is provided on the upper surface of the gate dielectric layer 4 at the bottom of the trench. The gate metal 5 and the gate dielectric layers 4 on both sides of the trench form a cavity, which serves as a biomolecule detection cavity 6.

[0096] like Figure 2 A method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes the following steps:

[0097] Step 1: For an N-type heavy doping concentration of 5 × 10⁻⁶ nm with a length of 170 nm and a thickness of 20 nm... 18 cm -3 Etching was performed on both sides of a rectangular silicon material, with each etched region being 10 nm long and 10 nm deep, resulting in a double-layered stepped drain region 3 on both sides. A lightly doped silicon material with a length of 150 nm and a thickness of 70 nm was epitaxially grown at the top of drain region 3, with a doping concentration of 1 × 10⁻⁶. 16 cm -3 This forms a silicon epitaxial wafer;

[0098] Step 2: Cover the silicon epitaxial wafer grown in Step 1 with a mask, and use photolithography to open etching windows. Use reactive ions to simultaneously etch the middle and both sides of the silicon epitaxial wafer. The width of the middle etched area is 26nm and the depth is 46nm, forming a trench structure. The length of the etched areas on both sides is 55nm and the depth is 30nm, forming a double-layer stepped structure. This reserves space for the subsequent growth of the gate dielectric layer 4, the gate metal 5 and the source region 1, and prepares the channel layer 2.

[0099] Step 3: Using molecular beam epitaxy (MBE), gallium arsenide with a length of 55 nm and a thickness of 30 nm is embedded in the double-layer stepped structure region etched on top of the channel layer 2 prepared in Step 2, and boron ion implantation is performed to form source region 1 with a doping concentration of 8 × 10⁻⁶. 19 cm -3 ;

[0100] Step 4: Use chemical vapor deposition to fill the trenches formed by etching in step 2 with hafnium oxide. Use an isotropic process to avoid the formation of voids in the oxide material. Planarize the surface of the oxide material to keep the oxide material level with the top of the trench layer 2, in preparation for subsequent patterning.

[0101] Step 5: Use reactive ion etching (Etch) to etch the hafnium oxide deposited in step 4. The etched area is 20 nm long and 44 nm deep, forming the growth site of the gate metal 5.

[0102] Step 6: Deposit gallium into the growth site of the gate metal 5 etched in step 5, and planarize the gallium to serve as the gate metal 5.

[0103] Step 7: Selective etching is used to etch the hafnium oxide on both sides of the gate metal 5 deposited in step 6 to form nanocavities on both sides of the gate metal 5.

[0104] Step 8: Hafnium oxide is grown on the sidewall of the channel layer 2 in the nanocavity formed in step 7 using chemical vapor deposition. Together with the hafnium oxide etched in step 5, it forms the gate dielectric layer 4, leaving a nanocavity with a length of 2nm and a depth of 44nm as the biomolecule detection cavity 6.

[0105] Step 9: Metallize the upper surface of source region 1 with gallium material to form a source contact 7 with a length of 45 nm and a thickness of 1 nm. Metallize the upper surface of the bottom step of drain region 3 with gallium material to form a drain contact 8 with a length of 5 nm and a thickness of 1 nm. The final structure is thus formed, i.e., a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor is formed.

[0106] Depend on Figure 7It is known that increasing the dielectric constant allows the device to have a larger saturation current at the same gate voltage. Compared with traditional TFET biosensors, it exhibits a higher on-state current. By comparing the transfer characteristics, Example 3 shows a lower on-state current of 4.82 × 10⁻⁶ at K = 1. -16 A / μm, exhibiting a high on-state current of 2.41 × 10⁻⁶ at K = 10. - 8 A / μm. Meanwhile, by Figure 8 It can be seen that Example 3 has a higher on-current sensitivity compared to the conventional TFET biosensor under different dielectric constants. At K=12, the on-current sensitivity of the conventional TFET biosensor is 1.27×10⁻⁶. 5 The conduction current sensitivity of Example 3 is 7.08 × 10⁻⁶. 7 This is 557 times that of traditional TFET biosensors. This indicates that Example 3 has a greater advantage in terms of sensitivity.

[0107] Example 4

[0108] like Figure 1 A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes a drain region 3 with two double-layer stepped shapes on both sides. Drain contacts 8 are provided on the upper surface of the bottom step on both sides of the drain region 3. A channel layer 2 with two double-layer stepped shapes on both sides is provided on the top step surface of the drain region 3. A source region 1 is provided at the steps on both sides of the channel layer 2. The source region 1 is in contact with both the upper surface of the bottom layer and the side of the top layer of the channel layer 2. A source contact 7 is provided on the upper surface of each source region 1. A trench is formed on the top layer of the channel layer 2. A gate dielectric layer 4 is provided in the trench. A gate metal 5 is provided on the upper surface of the gate dielectric layer 4 at the bottom of the trench. The gate metal 5 and the gate dielectric layers 4 on both sides of the trench form a cavity, which serves as a biomolecule detection cavity 6.

[0109] like Figure 2 A method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor includes the following steps:

[0110] Step 1: For an N-type heavy doping concentration of 5 × 10⁻⁶ nm with a length of 164 nm and a thickness of 20 nm... 18 cm -3 Etching was performed on both sides of a rectangular silicon material, with each etched region being 7 nm long and 8 nm deep, resulting in a double-layered stepped drain region 3 on both sides. A lightly doped silicon material with a length of 150 nm and a thickness of 75 nm was epitaxially grown at the top of drain region 3, with a doping concentration of 1 × 10⁻⁶. 16 cm -3 This forms a silicon epitaxial wafer;

[0111] Step 2: Cover the silicon epitaxial wafer grown in Step 1 with a mask, and use photolithography to open etching windows. Use reactive ions to simultaneously etch the middle and both sides of the silicon epitaxial wafer. The middle etched region is 26nm long and 50nm deep to form a trench structure. The two etched regions are both 59nm long and 30nm deep to form a double-layer stepped structure, which reserves space for the subsequent growth of the gate dielectric layer 4, gate metal 5 and source region 1, and is used to prepare the channel layer 2.

[0112] Step 3: Using molecular beam epitaxy (MBE), a germanium-silicon layer with a length of 59 nm and a thickness of 30 nm is embedded in the double-layer stepped structure region etched on top of the channel layer 2 prepared in Step 2, and boron ion implantation is performed to form source region 1 with a doping concentration of 1 × 10⁻⁶. 20 cm -3 ;

[0113] Step 4: Use chemical vapor deposition to fill the trenches formed by etching in step 2 with aluminum oxide. Use an isotropic process to avoid voids in the oxide material and planarize the surface of the oxide material to keep the oxide material level with the top of the trench layer 2, in preparation for subsequent patterning.

[0114] Step 5: Use reactive ion etching (Etch) to etch the aluminum oxide deposited in step 4. The etched area has a length of 20 nm and a depth of 48 nm to form the growth site of the gate metal 5.

[0115] Step 6: Deposit hafnium into the growth site of the gate metal 5 etched in Step 5, and planarize the hafnium to serve as the gate metal 5.

[0116] Step 7: Selective etching is used to etch the aluminum oxide on both sides of the gate metal 5 deposited in step 6 to form nanocavities on both sides of the gate metal 5.

[0117] Step 8: Aluminum oxide is grown on the sidewall of the channel layer 2 in the nanocavity formed in step 7 using chemical vapor deposition. Together with the aluminum oxide etched in step 5, it forms the gate dielectric layer 4, leaving a nanocavity with a length of 2nm and a depth of 48nm as the biomolecule detection cavity 6.

[0118] Step 9: Metallize the upper surface of source region 1 with hafnium material to form a source contact 7 with a length of 45 nm and a thickness of 1 nm. Metallize the upper surface of the bottom step of drain region 3 with hafnium material to form a drain contact 8 with a length of 5 nm and a thickness of 1 nm. The final structure is thus formed, that is, a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor is formed.

[0119] Depend on Figure 9It is known that increasing the dielectric constant allows the device to have a larger saturation current at the same gate voltage. Compared with traditional TFET biosensors, it exhibits a higher on-state current. By comparing the transfer characteristics, Example 4 shows a lower on-state current of 1.09 × 10⁻⁶ at K = 1. -14 A / μm, exhibiting a high on-state current of 6.86 × 10⁻⁶ at K = 10. - 8 A / μm. Meanwhile, by Figure 10 It can be seen that Example 4 has a higher on-current sensitivity compared to the conventional TFET biosensor under different dielectric constants. At K=12, the on-current sensitivity of the conventional TFET biosensor is 1.27×10⁻⁶. 5 The conduction current sensitivity of Example 4 is 6.28 × 10⁻⁶. 6 This is 49 times that of a traditional TFET biosensor. This indicates that Example 4 has a greater advantage in terms of sensitivity.

Claims

1. A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor, characterized in that, It includes a drain region (3) with double-layer stepped shape on both sides. Drain contacts (8) are provided on the upper surface of the bottom step on both sides of the drain region (3). A channel layer (2) with double-layer stepped shape on both sides is provided on the top step surface of the drain region (3). A source region (1) is provided at the step on both sides of the channel layer (2). The source region (1) is in contact with the upper surface of the bottom layer and the side of the top layer of the channel layer (2). A source contact (7) is provided on the upper surface of each source region (1). A trench is opened on the top layer of the channel layer (2). A gate dielectric layer (4) is provided in the trench. A gate metal (5) is provided on the upper surface of the gate dielectric layer (4) at the bottom of the trench. The gate metal (5) and the gate dielectric layer (4) on both sides of the trench form a cavity, which serves as a biomolecule detection cavity (6).

2. A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to claim 1, characterized in that, The bottom layer of the drain region (3) has a length of 160-170 nm and a thickness of 8-12 nm, while the top layer has a length of 140-150 nm and a thickness of 5-10 nm. Each drain contact (8) has a length of 4–5 nm and is less than nm, with a thickness of 1–2 nm; The bottom layer of the channel layer (2) has the same length as the top layer of the drain region (3) and a thickness of 40-45 nm. The top layer of the channel layer (2) on both sides of the trench has a length of 3-8 nm, a thickness of 30-35 nm, a trench depth of 45-50 nm, and a width of 26-28 nm. The length of each source region (1) is nm, the thickness of the top layer of the channel layer (2); Each of the source contacts (7) has a length of 45-48 nm, which is less than the length of the source region (1), and a thickness of 1-2 nm. The gate dielectric layer (4) is adapted to the trench size. The bottom length of the gate dielectric layer (4) is the same as the trench width, the layer thickness is 1-3nm, the length of both sides is 1-2nm, and the thickness is the same as the trench depth. The gate metal (5) has a length of 16-20 nm and a thickness of the trench depth minus the bottom thickness of the gate dielectric layer (4) in nm. The depth of the biomolecule detection cavity (6) is the same as the thickness of the gate metal (5), and the width is... nm.

3. A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to claim 1, characterized in that, The source region (1) is heavily P-type doped with a doping concentration of 5 × 10⁻⁶. 19 ~5×10 20 cm -3 ; The channel layer (2) is lightly doped with N-type doping and the doping concentration is 1×10⁻⁶. 15 ~5×10 17 cm -3 ; Drain region (3) is heavily N-type doped with a doping concentration of 5 × 10⁻⁶. 18 ~1×10 19 cm -3 .

4. A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to claim 1, characterized in that, The source region (1) is a III-V group material; Both the channel layer (2) and the drain region (3) are made of silicon material; The gate dielectric layer (4) is an oxide material; The gate metal (5), source contact (7) and drain contact (8) are all made of metal.

5. A biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to claim 4, characterized in that, The group III-V materials are germanium silicon, indium arsenide, or gallium arsenide. The oxide material is aluminum oxide, silicon dioxide, or hafnium dioxide; The metal material is hafnium, aluminum, or gallium.

6. A method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Etch both sides of the rectangular heavily doped silicon material to obtain a drain region (3) with double-layer stepped structure on both sides. Lightly doped silicon material is epitaxially grown on the top of the drain region (3) to form a silicon epitaxial wafer. Step 2: Cover the silicon epitaxial wafer grown in Step 1 with a mask, and use photolithography to open an etching window. Reactive ions simultaneously etch the middle and both sides of the silicon epitaxial wafer, forming a trench structure in the middle and a double-layer stepped structure on both sides, reserving space for the subsequent growth of the gate dielectric layer (4), gate metal (5) and source region (1), and preparing the channel layer (2). Step 3: Molecular beam epitaxy (MBE) is used to embed a group III-V material into the double-layer stepped structure region formed by etching on the top of the channel layer (2) prepared in step 2, and B ion implantation is performed to form the source region (1); Step 4: Use chemical vapor deposition to fill the trenches formed by etching in step 2 with oxide material. Use an isotropic process to avoid the formation of voids in the oxide material. Planarize the surface of the oxide material so that the oxide material is level with the top of the trench layer (2) to prepare for subsequent patterning. Step 5, use reactive ion etching (Etch) to form the growth site of the gate metal (5) using the oxide material deposited in step 4; Step 6: Deposit metal material into the growth location of the gate metal (5) etched in step 5, and planarize the metal material as the gate metal (5); Step 7: Selective etching is used to etch the oxide material on both sides of the gate metal (5) deposited in step 6 to form nanocavities on both sides of the gate metal (5). Step 8: Using chemical vapor deposition, oxide material is grown on the sidewall of the channel layer (2) in the nanocavity formed in step 7, and together with the oxide material etched in step 5, a gate dielectric layer (4) is formed, leaving a nanocavity as a biomolecular detection cavity (6). Step 9: Metallize the upper surface of the source region (1) to form a source contact (7), and metallize the upper surface of the bottom step of the drain region (3) to form a drain contact (8), thus fabricating the final structure, i.e., fabricating a biosensor based on a parallel tunnel junction vertical tunneling field-effect transistor.

7. The method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to claim 6, characterized in that, The drain region (3) mentioned in step 1 is heavily N-type doped with a doping concentration of 5 × 10⁻⁶. 18 ~1×10 19 cm -3 ; The channel layer (2) mentioned in step 2 is lightly doped N-type with a doping concentration of 1×10⁻⁶. 15 ~5×10 17 cm -3 ; The source region (1) mentioned in step 2 is heavily p-type doped with a doping concentration of 5 × 10⁻⁶. 19 ~5×10 20 cm -3 .

8. The method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to claim 6, characterized in that, The group III-V materials are germanium silicon, indium arsenide, or gallium arsenide. The oxide material is aluminum oxide, silicon dioxide, or hafnium dioxide; Both the source contact (7) and the drain contact (8) are made of metallic materials; The metal material is hafnium, aluminum, or gallium.

9. The method for fabricating a biosensor based on a parallel tunneling junction vertical tunneling field-effect transistor according to claim 6, characterized in that, In step 1, the bottom layer of the drain region (3) has a length of 160-170 nm and a thickness of 8-12 nm, while the top layer has a length of 140-150 nm and a thickness of 5-10 nm. In step 2, the bottom layer of the channel layer (2) has the same length as the top layer of the drain region (3), and the thickness is 40-45 nm. The top layer has a length of 3-8 nm and a thickness of 30-35 nm. The trench structure has a depth of 45-50 nm and a width of 26-28 nm. In step 3, the length of the source region (1) is nm, the thickness is the same as the top layer thickness of the channel layer (2); The gate metal (5) deposited in step 6 has a length of 16-20 nm and a thickness of the trench depth minus the bottom thickness of the gate dielectric layer (4) in nm. The gate dielectric layer (4) formed in step 8 is adapted to the trench size. The bottom length of the gate dielectric layer (4) is the same as the trench width, the layer thickness is 1-3 nm, and the lengths on both sides are 1-2 nm, with the thickness being the same as the trench depth. The depth of the biomolecule detection cavity (6) is the same as the thickness of the gate metal (5), and the width is... nm; The source contact (7) obtained by metallization in step 9 has a length of 45-48 nm, which is less than the length of the source region (1), and a thickness of 1-2 nm; the drain contact (8) has a length of 4-5 nm, which is less than the length of the source region (1). nm, with a thickness of 1-2 nm.

Images