Metal semiconductor field effect transistor biosensor with embedded biomolecule detection cavity

Abstract

A metal semiconductor field effect transistor biosensor with an embedded biomolecule detection cavity comprises a substrate, a buffer layer arranged above the substrate, a channel arranged above the buffer layer, a source region and a drain region respectively arranged on two sides above the channel, source electrode metal arranged above the source region, drain electrode metal arranged above the drain region, and a groove arranged in the middle of the channel, a biomolecule detection cavity is arranged above one side, close to the drain electrode, of the groove, and a grid electrode is arranged above one side, close to the source region, of the biomolecule detection cavity; after biomolecules with different dielectric constants enter the biomolecule detection cavity, the depletion layer capacitance of the device is changed, so that the electric field distribution and carrier concentration of a channel of the device are changed, the electrical characteristics of the device are changed, and the characteristics of the biomolecules are detected; signal transduction is realized by directly contacting a depletion layer capacitor of a channel, and the sensitivity and the stability are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a metal semiconductor field effect transistor biosensor with a built-in biomolecule detection cavity. Background Art

[0002] With the growing demand for biomedical testing, biosensors based on semiconductor devices have become a research hotspot due to their high sensitivity, rapid response and miniaturization potential. Although traditional silicon-based field-effect transistor (FET) biosensors are widely used, their material properties (such as low electron mobility and poor high-temperature stability) limit their performance in extreme environments (such as high temperature and strong electromagnetic interference). In addition, the intrinsic body resistance of silicon-based devices is high and they are easily interfered by ions in biological samples, resulting in a decrease in the signal-to-noise ratio. In contrast, silicon carbide (SiC), as a wide bandgap semiconductor material, has high electron mobility (~2μm 2 / (V·s)), high breakdown field strength (~3MV / cm) and excellent thermal conductivity (~15W / m·K), and can operate stably in high temperature (>200℃) and strong radiation environments. In addition, the intrinsic bulk resistance of SiC is 1 to 2 orders of magnitude higher than that of silicon, which significantly reduces the interference of ions in biological samples on the electrical characteristics of the device. Moreover, the gate and channel of the MESFET are in direct contact, and the specific recognition of biomolecules can be achieved through capacitive coupling between the gate and the biomolecules. When a biomolecule is adsorbed near the gate, the change in its dielectric constant (ε_r) will significantly change the gate capacitance, thereby regulating the threshold voltage (Vth) and leakage current (Ioff) to form a detectable electrical signal.

[0003] Patent application number 202011516842.4 discloses a "biosensor based on a nanosheet stack field-effect transistor and its preparation method." Three vertically stacked nanosheets form a channel, with a nanocavity etched near the source end. This structure overcomes the short-channel effect, but suffers from low sensitivity.

[0004] While traditional silicon-based field-effect transistor (FET) biosensors are widely used, their material properties (such as low electron mobility and poor high-temperature stability) limit their performance in extreme environments (such as high temperatures and strong electromagnetic interference). Furthermore, the presence of an insulating layer between the gate and the channel makes biomolecule detection dependent on capacitive coupling through the insulating layer, which is susceptible to interface traps and temperature drift.

[0005] The journal IEEE TRANSACTIONS ON NANOBIOSCIENCE published a paper titled "Study and Analysis of the Effects of SiGe Source and Pocket-Doped Channel on Sensing Performance of Dielectrically Modulated Tunnel FET-Based Biosensors." The paper uses silicon germanium as the source and introduces an N+ pocket-doped region into the TFET. While the device exhibits high sensitivity, the insulating layer between the gate and channel reduces its switching speed.

[0006] The Journal of Computational Electronics published a paper titled "Impact of triple-material gate and highly doped source / drain extensions onsensitivity of DNA biosensors." This triple-material gate improves sensitivity but at the expense of high power consumption. However, a layer of silicon dioxide separates the nanoscale detection cavity and the channel, increasing interface defects. Summary of the Invention

[0007] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a metal semiconductor field effect transistor biosensor with an embedded biomolecule detection cavity. The metal semiconductor field effect transistor realizes signal transduction through the depletion layer capacitance of the direct contact channel, providing a solution for improving the sensitivity and stability of the biosensor.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A metal semiconductor field effect transistor biosensor with an embedded biomolecule detection cavity includes a substrate 9, a buffer layer 8 is provided above the substrate 9, a channel 5 is provided above the buffer layer 8, a source region 3 and a drain region 4 are provided on both sides above the channel, a source metal 1 is provided above the source region 3, and a drain metal 2 is provided above the drain region 4. A biomolecule detection cavity 7 is embedded above the side of the channel 5 near the drain region 4, and a gate 6 is provided above the side of the biomolecule detection cavity 7 near the source region 3.

[0010] The source region 3 , drain region 4 , channel 5 , buffer layer 8 , and substrate 9 are all made of wide bandgap materials.

[0011] The wide bandgap material includes SiC and GaN.

[0012] The length and depth of the biomolecule detection cavity 7 embedded in the channel 5 are proportional to the sensitivity of the sensor.

[0013] The biomolecule detection cavity 7 is embedded in the channel 5 in a length range of 17.5 nm to 67.5 nm and a depth range of 2.5 nm to 7.5 nm.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) The gate 6 and the channel 5 of the metal semiconductor field effect transistor are in direct contact, and no insulating layer is required between the gate 6 and the channel 5, which significantly reduces the gate parasitic capacitance Cgs and Cgd.

[0016] (2) By setting up the biomolecule detection cavity 7 embedded in the channel 5, after the biomolecule enters the detection cavity, the change in dielectric constant will change the width of the depletion layer region of the metal semiconductor field effect transistor, thereby changing the electrical parameters of the device such as the threshold voltage.

[0017] (3) Metal-semiconductor field-effect transistors usually use semiconductor materials such as SiC, whose electron mobility is much higher than that of Si, making the channel resistance of metal-semiconductor field-effect transistors lower, the current driving capability stronger, and the switching speed faster.

[0018] (4) The gate 6 of the metal semiconductor field effect transistor is in direct contact with the semiconductor material of the channel 5 to form gate control. There is no need to grow a high-quality insulating layer, which reduces the process complexity and avoids the influence of insulating layer defects (such as interface states, traps, etc.) on device performance.

[0019] In summary, the metal semiconductor field effect transistor biosensor with an embedded biomolecule detection cavity of the present invention realizes signal transduction through the depletion layer capacitance of the direct contact channel, which significantly improves the sensitivity and stability of the biosensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural diagram of the present invention; wherein, Figure 1 is the main view.

[0021] Figure 2 This is a curve diagram of the computer-aided design software simulation characteristics of the present invention.

[0022] Figure 3 ION / IOFF sensitivity diagram of the biosensor of the present invention at different dielectric constants.

[0023] Markings in the figure: 1 is source metal, 2 is drain metal, 3 is source region, 4 is drain region, 5 is channel, 6 is gate, 7 is biomolecule detection cavity, 8 is buffer layer, and 9 is substrate. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] The working principle of the present invention is:

[0026] See also Figure 1 A metal semiconductor field effect transistor biosensor with an embedded biomolecule detection cavity includes a substrate 9, a buffer layer 8 is provided above the substrate 9, a channel 5 is provided above the buffer layer 8, a source region 3 and a drain region 4 are provided on both sides above the channel 5, a source metal 1 is provided above the source region 3, and a drain metal 2 is provided above the drain region 4. A biomolecule detection cavity 7 is embedded above the side of the channel 5 near the drain region 4, and a gate 6 is provided above the side of the biomolecule detection cavity 7 near the source region 3.

[0027] The source region 3 , drain region 4 , channel 5 , buffer layer 8 , and substrate 9 are all made of wide bandgap materials.

[0028] The wide bandgap materials include SiC and GaN, whose electron mobility is much higher than that of Si, so that the channel resistance of the metal semiconductor field effect transistor is lower, the current driving capability is stronger, and the switching speed is faster.

[0029] The biomolecule detection cavity 7 is embedded in the channel 5 in a length range of 17.5 nm to 67.5 nm and a depth range of 2.5 nm to 7.5 nm.

[0030] The length and depth of the biomolecule detection cavity 7 embedded in the channel 5 are proportional to the sensitivity of the sensor. The larger the length and depth, the higher the sensor sensitivity.

[0031] The working principle of the present invention is:

[0032] The gate 6 directly forms a Schottky contact with the channel 5; the source metal 1 and the source region 3, and the drain metal 2 and the drain region 4 form ohmic contacts for carrier injection and collection; the source region 3 is usually grounded, and the drain region 4 is connected to a positive voltage; for a depletion-mode metal semiconductor field-effect transistor biosensor, the conductivity of the channel 5 is controlled by adjusting the voltage of the gate 6; the drain region voltage drives electrons to flow from the source region 3 to the drain region 4, forming a drain current; after biomolecules with different dielectric constants enter the biomolecule detection cavity 7, the depletion layer capacitance of the device is changed, thereby changing the electric field distribution and carrier concentration in the device channel, causing the electrical characteristics of the device to change, realizing the characteristics of detecting biomolecules.

[0033] Simulation experiment:

[0034] See also Figure 2 By changing the dielectric constant of the material in the biomolecule detection cavity, when the biomolecule enters the detection cavity, the change in dielectric constant will change the width of the depletion layer region of the metal semiconductor field effect transistor, thereby changing the electrical parameters of the device such as the drain current. Figure 2 It can be seen that under different dielectric constants, the transfer characteristic curve of the device has a large change, and the device has a higher turn-on current, and therefore has a higher operating speed. Figure 3 The Ion / Ioff sensitivity of the device at different dielectric constants is shown. When the dielectric constant of biomolecules is 25, the Ion / Ioff sensitivity of the field effect transistor biosensor shows a high level, reaching 10 8 This is because metal-semiconductor field-effect transistors usually use semiconductor materials such as SiC, whose electron mobility is much higher than that of Si, making the channel resistance of metal-semiconductor field-effect transistors lower, the current driving capability stronger, and the switching speed faster. Figure 2 It can be seen that the device has a high turn-on current of up to 10 -3 A / μm, compared with the existing sensor leakage current of 10 -6 Therefore, it can be seen that the biosensor based on metal semiconductor field effect transistors, which etches a biomolecule detection cavity in the channel below the gate near the drain side for detecting biomolecules, can greatly improve the operating speed of the biosensor. In addition, the biosensor based on metal semiconductor field effect transistors has high sensitivity and switching speed.

[0035] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A metal semiconductor field effect transistor biosensor with an embedded biomolecule detection cavity, comprising a substrate (9), a buffer layer (8) disposed above the substrate (9), and a channel (5) disposed above the buffer layer (8), characterized in that: A source region (3) and a drain region (4) are respectively provided on both sides above the channel (5); a source metal (1) is provided above the source region (3); a drain metal (2) is provided above the drain region (4); a biomolecule detection cavity (7) is embedded above one side of the channel (5) near the drain region (4); and a gate (6) is provided above one side of the biomolecule detection cavity (7) near the source region (3).

2. The metal-semiconductor field-effect transistor biosensor with a built-in biomolecule detection cavity according to claim 1, characterized in that: The source region (3), drain region (4), channel (5), buffer layer (8), and substrate (9) are all made of wide bandgap materials.

3. The metal-semiconductor field-effect transistor biosensor with a built-in biomolecule detection cavity according to claim 1 or 2, characterized in that: The wide bandgap material includes SiC and GaN.

4. The metal-semiconductor field-effect transistor biosensor with a built-in biomolecule detection cavity according to claim 1, characterized in that: The length and depth of the biomolecule detection cavity (7) embedded in the channel (5) are proportional to the sensitivity of the sensor.

5. The metal-semiconductor field-effect transistor biosensor with a built-in biomolecule detection cavity according to claim 4, characterized in that: The biomolecule detection cavity (7) is embedded in the channel (5) in a length range of 17.5 nm to 67.5 nm and a depth range of 2.5 nm to 7.5 nm.

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