A schottky barrier field effect transistor biosensor having dumbbell-shaped channels

Abstract

A Schottky barrier field effect transistor biosensor with dumbbell-shaped channel comprises a dumbbell-shaped channel, one side of the middle recess of which is provided with a source, and the other side is provided with a drain, and the outer side of the protrusion of the dumbbell-shaped channel is respectively provided with a gate dielectric layer, one side of the gate dielectric layer close to the source is provided with a biological molecule detection cavity, and the outer side of the gate dielectric layer and the biological molecule detection cavity is provided with a gate; the present application adopts the dumbbell-shaped channel, the source and the drain are placed at the two opposite corners of the upper left and the lower right of the channel, the contact area of the source and the channel is increased, that is, the area of the Schottky contact is increased, and the occurrence probability of the Schottky tunneling is increased; and the contact surface of the source and the channel and the channel surface formed by the drain and the channel form a certain angle, which is beneficial to the movement of the carriers, so on the whole, the drain current is increased, and the sensitivity also shows a significant advantage, which brings a new technical breakthrough and application prospect for the field of biosensing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor devices, and particularly relates to a Schottky barrier field effect transistor biosensor with a dumbbell-shaped channel. BACKGROUND

[0002] In the development process of current biosensing technology, field effect transistor (FET) based biosensors are favored due to their efficient conversion of chemical information into readable electrical signals, miniaturization, simplified manufacturing process, rapid response, and high sensitivity. In particular, under the increasing demand for sensitivity and response speed in the biomedical field, traditional metal oxide semiconductor field effect transistor (MOSFET) and tunnel field effect transistor (TFET) biosensors expose their inherent technical bottlenecks. These bottlenecks mainly include: the increase in thermal budget due to the high doping requirement of the source and drain, which in turn leads to the complication of the biosensor manufacturing process; and the carrier diffusion caused by the difference in doping concentration between the source and drain and the channel, forming a non-ideal abrupt structure and thus reducing the device performance. In addition, the low drain current of TFET and the lower current switching ratio of MOSFET limit their operating speed and sensitivity.

[0003] The patent document with application number 202011516842.4 discloses a "nanoplate stacked field effect transistor-based biosensor and preparation method" scheme, in which three vertically stacked nanoplates constitute the channel, and a nanocavity is etched on the side close to the source. This structure overcomes the short channel effect, but has the disadvantage of low sensitivity.

[0004] The patent document with application number 202310296893.8 discloses a "biosensor based on inverted T-shaped negative capacitance tunneling field effect transistor and preparation method" scheme, in which the channel region adopts an inverted T-shaped structure, and the gate dielectric layer adopts an L-shaped structure. This structure increases the on-current of the sensor, but has the disadvantage of low sensitivity.

[0005] The journal "IEEE TRANSACTIONS ON NANOBIOSCIENCE" published a "L-Shaped High-Performance Schottky Barrier FET as Dielectrically Modulated Label Free Biosensor" scheme, which adopts an L-shaped vertical channel structure, and the source and drain adopt ErSi1.7 material to form Schottky contact with the channel. This device has high sensitivity, but the preparation process is complex. SUMMARY

[0006] In order to overcome the problems existing in the prior art, the Schottky barrier field effect transistor biosensor with a dumbbell-shaped channel aims to increase the contact area of the source and the channel, i.e., the area of the Schottky contact, and increase the probability of Schottky tunneling by adopting the dumbbell-shaped channel, with the source and the drain being placed at two opposite corners of the upper left and the lower right of the channel; and the contact surface of the source and the channel is at a certain angle with the channel surface formed by the drain and the channel, which is beneficial to the movement of the carriers, thus increasing the drain current in general and exhibiting significant advantages in sensitivity, thus bringing new technical breakthroughs and application prospects to the field of biosensing.

[0007] In order to achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] The Schottky barrier field effect transistor biosensor with a dumbbell-shaped channel comprises a dumbbell-shaped channel 1, a source 2 arranged on one side of the recessed part in the middle of the dumbbell-shaped channel 1, and a drain 3 arranged on the other side, with a gate dielectric layer 4 symmetrically arranged on the outer side of the recessed part in the middle of the dumbbell-shaped channel 1, a biological molecule detection cavity 6 arranged on the side of the gate dielectric layer 4 close to the source 2, and a gate 5 arranged on the outer side of the gate dielectric layer 4 and the biological molecule detection cavity 6.

[0009] The channel 1 is intrinsic P-type and is made of a wide band gap material.

[0010] The wide band gap material comprises 4H-SiC, SiC or GaN.

[0011] The source 2 and the drain 3 are made of a metal silicide, including ErSi1.7 and NiSi.

[0012] The gate dielectric layer 5 is made of an insulating oxide, including HfO2 and SiO2.

[0013] The gate 4 is made of a metal material, including hafnium and aluminum.

[0014] The coupling capacitance between the gate 6, the gate dielectric layer 5 and the channel 1 is calculated by the following formula:

[0015]

[0016] Wherein, K is the dielectric constant of the insulator, d is the thickness of the insulator, W is the width of the insulator, and L is the length of the insulator; when the dielectric constant of the biological molecules in the biological molecule detection cavity below the gate changes, the coupling capacitance changes, and the greater the dielectric constant of the biological molecules and the smaller the thickness of the insulating layer, the greater the coupling capacitance and the stronger the coupling, i.e., the greater the electrical property change of the biosensor.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] (1) The present application adopts a dumbbell-shaped channel, and the source and the drain are placed at the two opposite corners of the upper left and the lower right of the channel. Compared with the traditional structure in which the source and the drain are at the two ends of the channel, the present application increases the contact area of the source and the channel, i.e. increases the area of the Schottky contact, and increases the probability of Schottky tunneling.

[0019] (2) The source and the channel form two Schottky contact surfaces with an included angle of 90 degrees. Compared with two parallel Schottky contact surfaces, the effective area of Schottky tunneling of the two Schottky contact surfaces with an included angle of 90 degrees is larger, and a part of the fan-shaped Schottky tunneling area is added, thus increasing the probability of Schottky tunneling.

[0020] (3) The present application is a biosensor, and the source and the drain are formed of metal or metal silicide to form a Schottky contact with the channel. The process is simpler, avoids the adverse effects of carrier diffusion, and also reduces the series resistance of the source-drain. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural diagram of the present application.

[0022] Figure 2 is a computer-aided design software simulation characteristic curve diagram of the present application.

[0023] Figure 3 is a comparison diagram of the sensitivity of the present application and the biosensor based on the traditional SB-FET to biomolecules with different dielectric constants.

[0024] Figure 4 is a schematic diagram of the area of Schottky tunneling of the present application and the traditional structure under the same Schottky contact area.

[0025] Marked in the figure: 1, dumbbell-shaped channel, 2, source, 3, drain, 4, gate dielectric layer, 5, gate, 6, biomolecule detection cavity. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0027] Reference Figure 1The Schottky barrier field effect transistor biosensor with dumbbell-shaped channel comprises a dumbbell-shaped channel 1, a source 2 arranged at one side of the middle recess of the dumbbell-shaped channel 1, and a drain 3 arranged at the other side of the middle recess of the dumbbell-shaped channel 1, and a gate dielectric layer 4 arranged at the outer side of the dumbbell-shaped channel 1, a biosensor detection cavity 6 arranged at the side of the gate dielectric layer 4 close to the source 2, and a gate 5 arranged at the outer side of the gate dielectric layer 4 and the biosensor detection cavity 6.

[0028] The channel 1 is intrinsic P type and is made of wide band gap material.

[0029] The wide band gap material comprises 4H-SiC, SiC or GaN.

[0030] The source 2 and the drain 3 are made of metal silicide, and comprise ErSi1.7 and NiSi.

[0031] The gate dielectric layer 5 is made of insulating oxide, and comprises HfO2 and SiO2.

[0032] The gate 6 is made of hafnium and aluminum.

[0033] The coupling capacitance between the gate 6, the gate dielectric layer 5 and the channel 1 is shown in the figure, and the coupling capacitance is calculated by the following formula: Figure 4

[0034]

[0035] Wherein, K is the dielectric constant of the insulator, d is the thickness of the insulator, W is the width of the insulator, and L is the length of the insulator; when the dielectric constant of the biological molecules in the biosensor detection cavity below the gate changes, the coupling capacitance changes, and the greater the dielectric constant of the biological molecules and the smaller the thickness of the insulating layer, the greater the coupling capacitance and the stronger the coupling, that is, the greater the electrical characteristic change of the biosensor, therefore, the thickness of the medium layer of the biosensor is reduced as much as possible under the condition allowed by the process, so as to enhance the sensitivity performance.

[0036] The working principle of the present application is as follows:

[0037] ​The biosensor based on the Schottky tunneling field effect transistor generates a nanometer-scale cavity for accommodating biological molecules by etching a part of the gate dielectric layer 4 on the source side, and when different types of biological molecules enter the biological molecule detection cavity 6, the dielectric constant of the gate dielectric layer 4 under the gate 5 changes, which modulates the channel 1, so that the electrical characteristics of the device change, and the greater the change in electrical characteristics, the higher the sensitivity of the biosensor. The channel of the present application is dumbbell-shaped, and the source 2 and the drain 3 are respectively located at the upper left and lower right corners of the dumbbell-shaped channel 1, which increases the contact area of the source and the channel and increases the area of the Schottky contact, so that more electrons can undergo Schottky tunneling, thereby increasing the drain current. And reduce the turn-on current of the biosensor when the dielectric constant is 1, increase the turn-on current when the dielectric constant is 12, thus increase the sensitivity of the biosensor to detect biological molecules.

[0038] Simulation experiment:

[0039] By changing the dielectric constant of the material in the biological molecule detection cavity, the transfer characteristic curves of the field effect transistor when the dielectric constant is 1, 3.9, 7 and 12 are simulated under the conditions of gate voltage of 1.2V and drain voltage of 1V, as shown in Figure 2 . Among them, the dielectric constant of 1 represents the case that there is no biological molecule in the biological molecule detection cavity, and K represents the case that there is biological molecule in the biological molecule detection cavity 6. As can be seen from Figure 2 , with the increase of gate voltage and dielectric constant, the drain current of the biosensor also increases. When the gate voltage is 1.2V and the dielectric constant is 12, the drain current of the biosensor reaches the maximum. The ratio of the drain current of the biosensor when there is biological molecule in the biological molecule detection cavity to the drain current when there is no biological molecule in the biological molecule detection cavity is defined as the drain current sensitivity, as shown in Figure 3 . Through the secondary processing of the drain current data, the drain current sensitivity curve shown in Figure 3 is obtained. The sensitivity of the present application is 2.13x107, which is 65 times higher than 3.3x105 of the traditional structure biosensor. Figure 4 The area diagram of the Schottky tunneling of the present application and the traditional structure under the same Schottky contact area is shown in

[0040] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement within the technical range disclosed by the present application and within the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A Schottky barrier field effect transistor biosensor with a dumbbell-shaped channel, comprising a dumbbell-shaped channel (1), characterized in that, One side of the recessed part of the dumbbell-shaped channel (1) is provided with a source electrode (2), and the other side is provided with a drain electrode (3), the protruding part of the outer side of the dumbbell-shaped channel (1) is respectively provided with a gate dielectric layer (4) in symmetry, the side of the gate dielectric layer (4) close to the source electrode (2) is provided with a biomolecule detection cavity (6), and the outer side of the gate dielectric layer (4) and the biomolecule detection cavity (6) is provided with a gate electrode (5).

2. The Schottky barrier field effect transistor biosensor having a dumbbell-shaped channel according to claim 1, wherein, The channel (1) is intrinsic P type and is made of a wide band gap material.

3. A Schottky barrier field effect transistor biosensor having a dumbbell-shaped channel according to claim 2, wherein, The wide band gap material includes 4H-SiC, SiC or GaN.

4. The Schottky barrier field effect transistor biosensor having a dumbbell-shaped channel according to claim 1, wherein, The source (2) and drain (3) materials are metal silicides, including ErSi 1.7 , NiSi.

5. The Schottky barrier field effect transistor biosensor having a dumbbell-shaped channel according to claim 1, wherein, The gate dielectric layer (4) is made of insulating oxide, including HfO2 and SiO2 materials.

6. The Schottky barrier field effect transistor biosensor having a dumbbell-shaped channel according to claim 1, wherein, The gate electrode (5) is made of metal material, including hafnium and aluminum.

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