Biosensor based on parallel tunneling junction vertical tunneling field effect transistor and preparation method thereof

Abstract

The invention 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 electrode 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, and a gate electrode arranged on the source regions; a source contact is arranged at the top of each source region, a groove is formed in the top layer of the channel layer, a gate dielectric layer is arranged in the groove, gate metal is arranged on the upper surface of the gate dielectric layer at the bottom of the groove, and a cavity generated by the gate metal and the gate dielectric layer is a biomolecule detection cavity; the preparation method comprises the following steps: etching a drain region and a channel layer, obtaining a target shape and a groove structure, embedding a source region and an oxide layer, etching part of the oxide layer and embedding gate metal, etching the oxide layer at two sides of the gate metal and growing a gate dielectric layer, forming a biomolecule detection cavity, and metalizing at part positions of the source region and the drain region to obtain a final structure. And the sensitivity of device current and biomolecule detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and particularly relates to a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor and a preparation method thereof, which are used for detecting unknown biomolecules. Background Art

[0002] Biosensors can detect, record and quantify physiological parameters and biochemical processes in the body, having a significant impact on disease diagnosis and health status assessment. The field effect transistor (FET) biosensor is an emerging biosensing technology, effectively solving defects such as high requirements for equipment and operations, high cost of markers, and great preparation difficulty. The biosensor based on the field effect transistor (FET) converts biological signals into electrical signals through biological recognition, and has a fast response speed, high detection accuracy, and low cost, so it has a very broad research prospect. With the continuous development of integrated circuits, the miniaturization of device sizes has made the short-channel effect of common MOSFETs more and more serious. Due to the working principle of its own carrier thermal injection, it is difficult to get rid of the limitation of 60 mv / dec for the subthreshold swing at room temperature, which also poses an obstacle to its high-speed detection.

[0003] Iman Chahardah Cherik et al. disclosed a "Dielectric Modulated Doping-Less Tunnel Field-Effect Transistor, a Novel Biosensor Based on Cladding Layer Concept" solution (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.), which introduced holes in the Ge source region by using the cladding layer concept, and two nano-cavities for filling biomolecules were carved out in the cladding layer. This structure can work at low voltage, but the sensitivity is not high. Vandana Devi Wangkheirakpam et al. disclosed an "N +"Pocket Doped Vertical TFET Based Dielectric-Modulated Biosensor Considering Non-Ideal Hybridization Issue: A Simulation Study” Solution (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 nano-cavity based on an N+-pocket doped vertical TFET (VTFET) was proposed. The device has nano-cavities around HfO 2 which enhances the capture area of the biosensor and has a high on-current, but has low sensitivity when detecting charged molecules. The patent application with the publication number CN112736142A discloses a biosensor based on a nanosheet stacked field effect transistor and a preparation method thereof. Three vertically stacked nanosheets form a channel, and a nano-cavity is etched on the side close to the source end. This structure overcomes the short-channel effect, but the disadvantages are high power consumption and a large subthreshold swing. Summary of the Invention

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

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A biosensor based on a parallel tunneling junction vertical tunneling field effect transistor, comprising a drain region 3 with double-layer stepped structures on both sides. Drain contacts 8 are arranged on the upper surfaces of the bottom steps on both sides of the drain region 3. A channel layer 2 with double-layer stepped structures on both sides is arranged on the surface of the top step of the drain region 3. Source regions 1 are arranged at both steps of the channel layer 2. The source regions 1 are simultaneously attached to the upper surface of the bottom layer and the side surface of the top layer of the channel layer 2. Source contacts 7 are arranged on the upper surfaces of each source region 1. A groove is formed on the top layer of the channel layer 2, and a gate dielectric layer 4 is arranged in the groove. A gate metal 5 is arranged on the upper surface of the gate dielectric layer 4 at the bottom of the groove. A cavity is formed between the gate metal 5 and the gate dielectric layer 4 on both sides of the groove, serving as a biomolecule detection cavity 6.

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

[0008] The length of each drain contact 8 is 4 - 5 nm and is less than The thickness is 1 - 2 nm;

[0009] The length of the bottom layer of the channel layer 2 is the same as the length of the top layer of the drain region 3, the thickness is 40 - 45 nm, the lengths of the top layers on both sides of the groove of the channel layer 2 are 3 - 8 nm respectively, the thickness is 30 - 35 nm, the depth of the groove is 45 - 50 nm, and the width is 26 - 28 nm;

[0010] The length of each source region 1 is The thickness is the same as the thickness of the top layer of the channel layer 2;

[0011] The length of each source contact 7 is 45 - 48 nm and is less than the length of the source region 1, and the thickness is 1 - 2 nm;

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

[0013] The length of the gate metal 5 is 16 - 20 nm, and the thickness is (the depth of the groove - the thickness of the bottom of the gate dielectric layer 4) nm;

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

[0015]

[0016] The source region 1 is P-type heavily doped, and the doping concentration is 5×10 19 ~5×10 20 cm -3 ;

[0017] The channel layer 2 is lightly doped N-type with a doping concentration of 1×10 15 ~5×10 17 cm -3 ;

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

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

[0020] The channel layer 2 and the drain region 3 are both silicon materials;

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

[0022] The gate metal 5, the source contact 7, and the drain contact 8 are all metal materials.

[0023] The III-V material is germanium silicon, or indium arsenide, or gallium arsenide;

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

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

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

[0027] Step 1, etch both sides of a rectangular heavily doped silicon material to obtain a drain region 3 with a 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 a mask on the silicon epitaxial wafer grown in Step 1, lithographically open an etching window, and simultaneously etch (Etch) the middle and both sides of the silicon epitaxial wafer by reactive ion etching. A trench structure is formed in the middle, and a double-layer stepped structure is formed on both sides to reserve space for the subsequent growth of the gate dielectric layer 4, the gate metal 5, and the source region 1, and a channel layer 2 is prepared;

[0029] Step 3, use molecular beam epitaxy (MBE) to embed a III-V material in the double-layer stepped structure region etched on the top of the channel layer 2 prepared in Step 2, and perform B ion implantation (Implantation) to form the source region 1;

[0030] Step 4, use chemical vapor deposition to fill the inside of the trench etched in Step 2 with an oxide material, adopt an isotropic process to avoid the formation of voids in the oxide material, and perform a planarization treatment on the surface of the oxide material to make the oxide material level with the top of the channel layer 2 to prepare for subsequent pattern processing;

[0031] Step 5: Use reactive ion etching (Etch) to etch the oxide material deposited in Step 4 to form the growth position of the gate metal 5;

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

[0033] Step 7: Use selective etching to etch the oxide materials on both sides of the gate metal 5 deposited in Step 6 to form nano-cavities on both sides of the gate metal 5;

[0034] Step 8: Use chemical vapor deposition to grow an oxide material in the nano-cavities formed in Step 7 on the sidewalls of the channel layer 2 to jointly form the gate dielectric layer 4 with the oxide material after etching in Step 5, and leave a nano-cavity as the biomolecule detection cavity 6;

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

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

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

[0038] The source region 1 described in Step 2 is P-type heavily doped with a doping concentration of 5×10 19 ~5×10 20 cm -3 .

[0039] The III-V material is germanium silicon, or indium arsenide, or gallium arsenide;

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

[0041] The source contact 7 and the drain contact 8 are both metal materials;

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

[0043] The bottom layer length of the drain region 3 in Step 1 is 160 - 170 nm, the thickness is 8 - 12 nm, the top layer length is 140 - 150 nm, and the thickness is 5 - 10 nm;

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

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

[0046] The length of the gate metal 5 formed by deposition in step 6 is 16 - 20 nm, and the thickness is (trench depth - bottom thickness of the gate dielectric layer 4) 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 each, and the thickness is 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 length of the source contact 7 obtained by metallization in step 9 is 45 - 48 nm and is less than the length of the source region 1, and the thickness is 1 - 2 nm; the length of the drain contact 8 is 4 - 5 nm and 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. The present 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 lateral tunneling and longitudinal tunneling. At the same time, the contact area between the source region 1 and the channel layer 2 is increased, thus increasing the tunneling surface area and the tunneling probability. When biomolecules enter the biomolecule detection cavity 6, the generation rate of band-to-band tunneling at the source region 1-channel layer 2 junction is increased, which can effectively make up for the defect of the low on-state current of the traditional horizontal p-i-n structure. At the same time, the effective coupling between the source region 1 and the channel layer 2 is enhanced, resulting in an increase in the turn-on current under different biomolecule dielectric constants K.

[0052] 2. The present invention disposes the gate metal 5 in the trench to form a trench gate. While ensuring the number of biomolecule detection cavities, the switching speed of the device is increased, and the device reliability is improved. Two biomolecule detection cavities 6 are established on both sides of the gate metal 5, so that the biomolecule detection cavity 6 can well regulate the conduction of two parallel tunneling junctions, enhancing the drain current of the sensor structure.

[0053] 3. The biomolecule detection cavity 6 of the present invention covers the entire tunneling region. The upper half cavity modulates the longitudinal tunneling, and the lower half cavity modulates the lateral tunneling, making the modulation effect differences of different biomolecules on the device channel more obvious and the sensing performance of the device better. The biomolecule detection cavity 6 is in the vertical direction, and biomolecules can enter the biomolecule detection cavity 6 better.

[0054] 4. The present invention is based on a vertical structure tunneling field effect transistor. Compared with complex structures such as core-shell nanotubes, it does not require multiple etching and multiple ion implantations, and the manufacturing process is simpler, reducing the process cost. The vertical structure is also more conducive to large-scale integration.

[0055] In summary, the biosensor based on the parallel tunneling junction vertical tunneling field effect transistor proposed by the present invention has a vertical structure, which is more conducive to large-scale integration. At the same time, the biomolecule detection cavity 6 is also vertically distributed. Under the action of gravity, biomolecules can enter the cavity more easily for analysis. The channel layer 2 is extended to wrap the source region 1, increasing the contact area between the source region 1 and the channel layer 2, thereby increasing the tunneling area. The gate metal 5 is placed in the trench to form a trench gate, which increases the switching speed of the device and improves the device 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 the sensitivity and stability. And there is still a lot of room for improvement and potential in other performance aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic structural diagram of the biosensor of the present invention.

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

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

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

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

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

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

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

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

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

[0066] Markings in the figure: 1 is the source region, 2 is the channel layer, 3 is the drain region, 4 is the gate dielectric layer, 5 is the gate metal, 6 is the biomolecule detection cavity, 7 is the source contact, and 8 is the drain contact. Detailed implementation manners

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

[0068] Embodiment 1

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

[0070] As Figure 2 , a preparation method for a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor includes the following steps:

[0071] Step 1: Etch both sides of a rectangular silicon material with a length of 160 nm, a thickness of 20 nm, and an N-type heavy doping concentration of 1×10 19 cm -3 . The etching regions have a length of 5 nm and a depth of 10 nm on both sides, obtaining a drain region 3 with double-layer stepped shapes on both sides. A lightly doped silicon material with a length of 150 nm and a thickness of 70 nm and a doping concentration of 5×10 15 cm-3 , a silicon epitaxial wafer is formed;

[0072] Step 2: Cover a mask on the silicon epitaxial wafer grown in Step 1, perform photolithography to open an etching window, and simultaneously etch (Etch) the middle and both sides of the silicon epitaxial wafer by reactive ion etching. The width of the middle etching region is 26 nm and the depth is 45 nm to form a trench structure. The lengths of the etching regions on both sides are both 56 nm and the depths are both 30 nm to form a double-layer stepped structure, reserving space for the subsequent growth of the gate dielectric layer 4, the gate metal 5, and the source region 1, and preparing it into a channel layer 2;

[0073] Step 3: Use molecular beam epitaxy (MBE) to embed gallium arsenide with a length of 56 nm and a thickness of 30 nm in the double-layer stepped structure region etched on the top of the channel layer 2 prepared in Step 2, and perform B ion implantation (Implantation) to form the source region 1 with a doping concentration of 1×10 20 cm -3 ;

[0074] Step 4: Use chemical vapor deposition to fill hafnium oxide into the trench etched in Step 2, adopt an isotropic process to avoid the formation of voids in the oxide material, and perform planarization treatment on the surface of the oxide material to make the oxide material level with the top of the channel layer 2, preparing for subsequent pattern processing;

[0075] Step 5: Use reactive ion etching (Etch) to etch the hafnium oxide deposited in Step 4. The length of the etching region is 16 nm and the depth is 43 nm to form the growth position of the gate metal 5;

[0076] Step 6: Deposit gallium into the growth position of the gate metal 5 etched in Step 5, and perform planarization treatment on the gallium to serve as the gate metal 5;

[0077] Step 7: Use selective etching to etch the hafnium oxide on both sides of the gate metal 5 deposited in Step 6 to form nano-cavities on both sides of the gate metal 5;

[0078] Step 8: Use chemical vapor deposition to grow hafnium oxide in the nano-cavities formed in Step 7 and on the sidewalls of the channel layer 2, which together with the hafnium oxide etched in Step 5 forms the gate dielectric layer 4, and leave a nano-cavity with a length of 3 nm and a depth of 43 nm as the biomolecule detection cavity 6;

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

[0080] It can be seen from Figure 3 that increasing the dielectric constant can make the saturation current of the device larger under the same gate voltage. Compared with the traditional TFET biosensor, it has a higher on-state current. By comparing the transfer characteristics, Example 1 has a lower on-state current of 1.42×10 -14 A / μm at K = 1, and a higher on-state current of 2.64×10 - 7 A / μm at K = 10. At the same time, it can be seen from Figure 4 that Example 1 has a greater on-current sensitivity compared with the traditional TFET biosensor under different dielectric constants. At K = 12, the on-current sensitivity of the traditional TFET biosensor is 1.27×10 5 , and the on-current sensitivity of Example 1 is 1.86×10 7 , which is 146 times that of the traditional TFET biosensor. It shows that Example 1 has more advantages in terms of sensitivity.

[0081] Example 2

[0082] For example, Figure 1 , a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor, includes a drain region 3 with double-layer stepped shapes on both sides. Drain contacts 8 are provided on the upper surfaces of the bottom steps on both sides of the drain region 3. A channel layer 2 with double-layer stepped shapes on both sides is provided on the top step surface of the drain region 3. Source regions 1 are provided at both stepped positions on both sides of the channel layer 2. The source regions 1 are simultaneously in contact with the upper surface of the bottom layer and the side surface of the top layer of the channel layer 2. Source contacts 7 are provided on the upper surfaces of each source region 1. A groove is provided on the top layer of the channel layer 2, and a gate dielectric layer 4 is provided in the groove. A gate metal 5 is provided on the upper surface of the gate dielectric layer 4 at the bottom of the groove. A cavity is formed between the gate metal 5 and the gate dielectric layer 4 on both sides of the groove, serving as a biomolecule detection cavity 6.

[0083] For example, Figure 2 , a preparation method of a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor includes the following steps:

[0084] Step 1: Etch both sides of a rectangular silicon material with a length of 170 nm, a thickness of 15 nm, and an N-type heavy doping concentration of 1×10 19 cm -3 . The etching regions have a length of 10 nm and a depth of 5 nm on both sides, obtaining a drain region 3 with double-layer stepped shapes on both sides. A lightly doped silicon material with a length of 150 nm and a thickness of 75 nm and a doping concentration of 1×10 17 cm -3 is epitaxially grown on the top of the drain region 3 to form a silicon epitaxial wafer;

[0085] Step 2: Cover a mask on the silicon epitaxial wafer grown in Step 1, and perform photolithography to open an etching window. Then, reactively etch the middle and both sides of the silicon epitaxial wafer simultaneously. The width of the etched area in the middle is 28 nm and the depth is 50 nm to form a trench structure. The length of the etched areas on both sides is 53 nm and the depth is 35 nm to form a double-layer stepped structure, reserving space for the subsequent growth of the gate dielectric layer 4, the gate metal 5, and the source region 1, and fabricating it into a channel layer 2.

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

[0087] Step 4: Use chemical vapor deposition to fill hafnium oxide into the trench etched in Step 2. An isotropic process is adopted to avoid the formation of voids in the oxide material, and the surface of the oxide material is planarized so that the oxide material is level with the top of the channel layer 2, preparing for subsequent patterning.

[0088] Step 5: Use reactive ion etching (Etch) to etch the hafnium oxide deposited in Step 4. The length of the etched area is 20 nm and the depth is 48 nm to form the growth position of the gate metal 5.

[0089] Step 6: Deposit gallium into the growth position of the gate metal 5 etched in Step 5, and perform planarization on the gallium to be used as the gate metal 5.

[0090] Step 7: Use selective etching to etch the hafnium oxide on both sides of the gate metal 5 deposited in Step 6 to form nano-cavities on both sides of the gate metal 5.

[0091] Step 8: Use chemical vapor deposition to grow hafnium oxide in the nano-cavities formed in Step 7 and on the sidewalls of the channel layer 2, which together with the hafnium oxide etched in Step 5 form the gate dielectric layer 4, and leave a nano-cavity with a length of 3 nm and a depth of 48 nm as the biomolecule detection cavity 6.

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

[0093] By Figure 5It can be seen that increasing the dielectric constant can make the saturation current of the device larger under the same gate voltage. Compared with the traditional TFET biosensor, it has a higher on-state current. By comparing the transfer characteristics, Example 2 has a lower on-state current of 1.73×10 -16 A / μm at K = 1 and a higher on-state current of 4.60×10 - 9 A / μm at K = 10. At the same time, it can be seen from Figure 6 that when K = 12, the on-current sensitivity of the traditional TFET biosensor is 1.27×10 5 , and the on-current sensitivity of Example 2 is 2.69×10 7 , which is 212 times that of the traditional TFET biosensor. It shows that Example 2 has more advantages in terms of sensitivity.

[0094] Example 3

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

[0096] As shown in Figure 2 , a preparation method of a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor includes the following steps:

[0097] Step 1: Etch both sides of a rectangular silicon material with a length of 170 nm, a thickness of 20 nm, and an N-type heavy doping concentration of 5×10 18 cm -3 . The etching regions on both sides have a length of 10 nm and a depth of 10 nm, obtaining a drain region 3 with double-layer stepped shapes on both sides. On the top of the drain region 3, a lightly doped silicon material with a length of 150 nm and a thickness of 70 nm is epitaxially grown, and the doping concentration is 1×10 16 cm -3 , forming a silicon epitaxial wafer;

[0098] Step 2: Cover a mask on the silicon epitaxial wafer grown in Step 1, and open an etching window through photolithography. Then, simultaneously etch the middle and both sides of the silicon epitaxial wafer by reactive ion etching (Etch). The width of the middle etching area is 26 nm and the depth is 46 nm to form a trench structure. The length of both side etching areas is 55 nm and the depth is 30 nm to form a double-layer stepped structure, reserving space for the subsequent growth of the gate dielectric layer 4, the gate metal 5, and the source region 1, and fabricating it into the channel layer 2;

[0099] Step 3: Use molecular beam epitaxy (MBE) to embed gallium arsenide with a length of 55 nm and a thickness of 30 nm in the double-layer stepped structure area etched on the top of the channel layer 2 prepared in Step 2, and perform B ion implantation (Implantation) to form the source region 1 with a doping concentration of 8×10 19 cm -3 ;

[0100] Step 4: Fill hafnium oxide into the trench etched in Step 2 using chemical vapor deposition. Use an isotropic process to avoid the formation of voids in the oxide material, and perform planarization treatment on the surface of the oxide material to make the oxide material level with the top of the channel layer 2, preparing for subsequent patterning;

[0101] Step 5: Use reactive ion etching (Etch) to etch the hafnium oxide deposited in Step 4. The length of the etching area is 20 nm and the depth is 44 nm to form the growth position of the gate metal 5;

[0102] Step 6: Deposit gallium into the growth position of the gate metal 5 etched in Step 5, and perform planarization treatment on the gallium to be used as the gate metal 5;

[0103] Step 7: Use selective etching to etch the hafnium oxide on both sides of the gate metal 5 deposited in Step 6 to form nano-cavities on both sides of the gate metal 5;

[0104] Step 8: Use chemical vapor deposition to grow hafnium oxide in the nano-cavities formed in Step 7 and on the sidewalls of the channel layer 2, which together with the hafnium oxide etched in Step 5 form the gate dielectric layer 4, and leave a nano-cavity with a length of 2 nm and a depth of 44 nm as the biomolecule detection cavity 6;

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

[0106] Consisting of Figure 7It can be seen that increasing the dielectric constant can make the saturation current of the device larger under the same gate voltage. Compared with the traditional TFET biosensor, it has a higher on-state current. By comparing the transfer characteristics, Example 3 has a lower on-state current of 4.82×10 -16 A / μm at K = 1, and a higher on-state current of 2.41×10 - 8 A / μm at K = 10. At the same time, it can be seen from Figure 8 that Example 3 has a greater on-current sensitivity compared with the traditional TFET biosensor under different dielectric constants. At K = 12, the on-current sensitivity of the traditional TFET biosensor is 1.27×10 5 , and the on-current sensitivity of Example 3 is 7.08×10 7 , which is 557 times that of the traditional TFET biosensor. It shows that Example 3 has more advantages in terms of sensitivity.

[0107] Example 4

[0108] As shown in Figure 1 , a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor includes a drain region 3 with double-layer stepped shapes on both sides. Drain contacts 8 are provided on the upper surfaces of the bottom steps on both sides of the drain region 3. A channel layer 2 with double-layer stepped shapes on both sides is provided on the surface of the top step of the drain region 3. Source regions 1 are provided at both stepped positions on both sides of the channel layer 2. The source regions 1 are simultaneously in contact with the upper surface of the bottom layer and the side surface of the top layer of the channel layer 2. Source contacts 7 are provided on the upper surfaces of each source region 1. A groove is formed on the top layer of the channel layer 2, and a gate dielectric layer 4 is provided in the groove. A gate metal 5 is provided on the upper surface of the gate dielectric layer 4 at the bottom of the groove. A cavity is formed between the gate metal 5 and the gate dielectric layer 4 on both sides of the groove, serving as a biomolecule detection cavity 6.

[0109] As shown in Figure 2 , a preparation method of a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor includes the following steps:

[0110] Step 1: Etch both sides of a rectangular silicon material with a length of 164 nm, a thickness of 20 nm, and an N-type heavy doping concentration of 5×10 18 cm -3 . The etching regions on both sides have a length of 7 nm and a depth of 8 nm each, to obtain a drain region 3 with double-layer stepped shapes on both sides. A lightly doped silicon material with a length of 150 nm and a thickness of 75 nm is epitaxially grown on the top of the drain region 3, and the doping concentration is 1×10 16 cm -3 to form a silicon epitaxial wafer;

[0111] Step 2: Cover a mask on the silicon epitaxial wafer grown in Step 1, and open an etching window through photolithography. Reactive ion etching (Etch) is simultaneously performed on the middle and both sides of the silicon epitaxial wafer. The length of the middle etching region is 26 nm, and the depth is 50 nm to form a trench structure. The length of both side etching regions is 59 nm, and the depth is 30 nm to form a double-layer stepped structure, reserving space for the subsequent growth of the gate dielectric layer 4, the gate metal 5, and the source region 1, and fabricating it into the channel layer 2;

[0112] Step 3: Use molecular beam epitaxy (MBE) to embed germanium silicon with a length of 59 nm and a thickness of 30 nm in the double-layer stepped structure region etched on the top of the channel layer 2 prepared in Step 2, and perform B ion implantation (Implantation) to form the source region 1 with a doping concentration of 1×10 20 cm -3 ;

[0113] Step 4: Use chemical vapor deposition to fill the inside of the trench etched in Step 2 with aluminum oxide. An isotropic process is used to avoid the formation of voids in the oxide material, and the surface of the oxide material is planarized so that the oxide material is level with the top of the channel layer 2, preparing for subsequent patterning;

[0114] Step 5: Use reactive ion etching (Etch) to etch the aluminum oxide deposited in Step 4. The length of the etching region is 20 nm, and the depth is 48 nm to form the growth position of the gate metal 5;

[0115] Step 6: Deposit hafnium into the growth position of the gate metal 5 etched in Step 5, and perform planarization on the hafnium as the gate metal 5;

[0116] Step 7: Use selective etching to etch the aluminum oxide on both sides of the gate metal 5 deposited in Step 6 to form nano-cavities on both sides of the gate metal 5;

[0117] Step 8: Use chemical vapor deposition to grow aluminum oxide in the nano-cavities formed in Step 7 and on the sidewalls of the channel layer 2, which together with the aluminum oxide etched in Step 5 forms the gate dielectric layer 4, and leave a nano-cavity with a length of 2 nm and a depth of 48 nm as the biomolecule detection cavity 6;

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

[0119] By Figure 9It can be seen that increasing the dielectric constant can make the saturation current of the device larger under the same gate voltage. Compared with the traditional TFET biosensor, it has a higher on-state current. By comparing the transfer characteristics, Example 4 has a lower on-state current of 1.09×10 -14 A / μm at K = 1, and a higher on-state current of 6.86×10 - 8 A / μm at K = 10. At the same time, it can be seen from Figure 10 that Example 4 has a greater on-current sensitivity compared with the traditional TFET biosensor at different dielectric constants. At K = 12, the on-current sensitivity of the traditional TFET biosensor is 1.27×10 5 , and the on-current sensitivity of Example 4 is 6.28×10 6 , which is 49 times that of the traditional TFET biosensor. It shows that Example 4 has more advantages in terms of sensitivity.

Claims

1. A biosensor based on a parallel tunneling junction vertical tunneling field effect transistor, characterized in that: The invention comprises a drain region (3) with double-layer stepped shapes on both sides, drain contacts (8) are arranged on the upper surfaces of the bottom steps on both sides of the drain region (3), a channel layer (2) with double-layer stepped shapes on both sides is arranged on the surface of the top step of the drain region (3), source regions (1) are arranged at the steps on both sides of the channel layer (2), the source regions (1) are simultaneously in contact with the bottom upper surface and the top side of the channel layer (2), each source region (1) is arranged on the upper surface, a groove is opened on the top of the channel layer (2), a gate dielectric layer (4) is arranged in the groove, a gate metal (5) is arranged on the upper surface of the gate dielectric layer (4) at the bottom of the groove, and the gate metal (5) and the gate dielectric layer (4) on both sides of the groove generate a cavity 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 drain region (3) has a bottom layer length of 160-170 nm and a thickness of 8-12 nm, and a top layer length of 140-150 nm and a thickness of 5-10 nm; Each drain contact (8) has a length of 4 to 5 nm and is smaller than Thickness is 1-2 nm; The bottom layer of the channel layer (2) is the same length as the top layer of the drain region (3) and has a thickness of 40 to 45 nm. The top layers of the channel layer (2) on both sides of the groove are 3 to 8 nm long and 30 to 35 nm thick respectively. The groove has a depth of 45 to 50 nm and a width of 26 to 28 nm. The length of each source region (1) is The thickness is the thickness of the top layer of the channel layer (2); Each of the source contacts (7) has a length of 45 to 48 nm, is smaller than the length of the source region (1), and has a thickness of 1 to 2 nm; The gate dielectric layer (4) is adapted to the size of the groove, the bottom length of the gate dielectric layer (4) is the same as the groove width, the layer thickness is 1 to 3 nm, the lengths on both sides are 1 to 2 nm, and the thickness is the same as the groove depth; The gate metal (5) has a length of 16 to 20 nm and a thickness equal to the groove 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 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 doped with P-type, with a doping concentration of 5×10 19 ~5×10 20 cm -3 ; The channel layer (2) is lightly doped with N-type, and the doping concentration is 1×10 15 ~5×10 17 cm -3 ; The drain region (3) is heavily N-type doped with a doping concentration of 5×10 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; The channel layer (2) and the drain region (3) are both made of silicon material; The gate dielectric layer (4) is made of an oxide material; The gate metal (5), the source contact (7) and the drain contact (8) are all made of metal materials.

5. A biosensor based on a parallel tunneling junction vertical tunneling field effect transistor according to claim 4, characterized in that: The III-V group material is germanium silicon, or 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 preparing 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: The following steps are involved: Step 1, etching both sides of the rectangular heavily doped silicon material to obtain a double-layer stepped drain region (3) on both sides, epitaxially growing a lightly doped silicon material on the top of the drain region (3) to form a silicon epitaxial wafer; Step 2, covering the silicon epitaxial wafer grown in step 1 with a mask, opening an etching window by photolithography, and simultaneously etching (Etch) the middle and both sides of the silicon epitaxial wafer by reactive ions, forming a trench structure in the middle and a double-layer step structure on both sides, thereby reserving space for the subsequent growth of a gate dielectric layer (4), a gate metal (5) and a source region (1), thereby preparing a channel layer (2); Step 3, using molecular beam epitaxy (MBE) to embed III-V group materials in the double-layer stepped structure region formed by etching on the top of the channel layer (2) prepared in step 2, and perform B ion implantation to form a source region (1); Step 4, using chemical vapor deposition to fill the inside of the groove formed by etching in step 2 with oxide material, using an isotropic process to prevent the oxide material from forming voids, and performing a planarization process on the surface of the oxide material so that the oxide material is level with the top of the channel layer (2), in preparation for subsequent graphic processing; Step 5, using reactive ion etching (Etch) to etch the oxide material deposited in step 4 to form a growth position for the gate metal (5); Step 6, depositing a metal material into the growth position of the gate metal (5) etched in step 5, and performing a planarization process on the metal material to serve as the gate metal (5); Step 7, using selective etching to etch the oxide material on both sides of the gate metal (5) deposited in step 6, so as to form nanocavities on both sides of the gate metal (5); Step 8, using chemical vapor deposition in the nanocavity formed in step 7, an oxide material is grown on the sidewall of the channel layer (2), and together with the oxide material etched in step 5, forms a gate dielectric layer (4), and a nanocavity is left as a biomolecule detection cavity (6); Step 9, metallizing the upper surface of the source region (1) to form a source contact (7), and metallizing the upper surface of the bottom step of the drain region (3) to form a drain contact (8), to prepare the final structure, that is, to prepare a biosensor based on a parallel tunneling junction vertical tunneling field effect transistor.

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

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

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

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