A temperature-salinity-depth sensor based on silicon nanochannel and a manufacturing method thereof

Abstract

The present invention belongs to the technical field of semiconductor sensors, and discloses a temperature-salinity depth sensor based on silicon nanochannels and a manufacturing method thereof; in the temperature-salinity depth sensor based on silicon nanochannels: a SiO2 buried oxide layer is arranged on the silicon substrate layer; three silicon nanochannels are arranged on the SiO2 buried oxide layer, and both sides of each silicon nanochannel are ohmic contact area silicon films; metal leads and electrode layers are arranged on the SiO2 buried oxide layer, and are connected to each ohmic contact area silicon film; the SiO2 isolation layer is used as a protective layer; a SiO2 gate oxide layer is arranged above one of the silicon nanochannels; a cavity used as a back cavity is arranged on the silicon substrate layer below one of the silicon nanochannels. The technical solution of the present invention solves the problems of complex structure, large volume, and low integration of traditional temperature-salinity depth sensors, and can ensure high-sensitivity detection and parameter consistency of the temperature-salinity depth sensor.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor sensors, relates to a sensitive unit structure and its manufacture, and in particular to a temperature-salinity-depth sensor based on a silicon nanochannel and a manufacturing method thereof. Background Art

[0002] Temperature-salinity-depth profilers are widely used in the field of ocean exploration. Their core components are high-precision temperature-salinity-depth sensors. Currently, temperature-salinity-depth measurements are usually achieved by configuring conductivity sensors, pressure sensors and temperature sensors. For example, the SBE-911Plus CTD developed by SEA-BIRD is equipped with a three-electrode conductivity sensor, a temperature sensor and a digital quartz pressure sensor with temperature compensation. For principle explanation, the conductivity sensor measures the conductivity of the water body to determine the salinity information of the water body; the temperature sensor measures the temperature of the water body to obtain the ocean temperature distribution information; the pressure sensor measures the pressure of the water body to convert and obtain the depth information of the water body.

[0003] Future ocean monitoring requires temperature, salinity and depth sensors to be durable, accurate and easy to integrate, which puts forward higher requirements on the energy consumption, volume, long-term stability, maintenance-free, self-calibration and platform adaptability of sensors. In the existing temperature, salinity and depth measurement technologies, the platinum resistance temperature sensors, multi-electrode conductivity sensors, piezoresistive or capacitive sensors used in temperature, salinity and depth sensors have the defects of complex structure, large volume and low integration, which cannot meet the trend of temperature, salinity and depth sensors to develop in the direction of miniaturization, low power consumption, fast response, low cost and high consistency, which limits the development and application of temperature, salinity and depth sensors to a certain extent. Summary of the invention

[0004] The purpose of the present invention is to provide a temperature-salinity-depth sensor based on silicon nanochannels and a manufacturing method thereof, so as to solve one or more of the above-mentioned technical problems. The temperature-salinity-depth sensor based on silicon nanochannels provided by the present invention solves the technical problems of the complex structure, large volume and low degree of integration of the existing traditional temperature-salinity-depth sensors; in addition, the present invention integrates the temperature sensing unit, salinity sensing unit and depth sensing unit into a single chip, which can measure the water temperature, salinity and other parameters in water bodies of different depths, ensuring the high sensitivity detection and parameter consistency of the temperature-salinity-depth sensor.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a temperature-salt depth sensor based on silicon nanochannels, the temperature-salt depth sensor based on silicon nanochannels comprises: a silicon substrate layer, a SiO2 buried oxide layer, a first silicon nanochannel, a second silicon nanochannel, a third silicon nanochannel, an ohmic contact region silicon film, a metal lead and electrode layer, a SiO2 isolation layer and a SiO2 gate oxide layer; wherein:

[0007] The SiO2 buried oxide layer is arranged on the silicon substrate layer;

[0008] The first silicon nanochannel, the second silicon nanochannel and the third silicon nanochannel are arranged on the SiO2 buried oxide layer, and both sides of the first silicon nanochannel, the second silicon nanochannel and the third silicon nanochannel are heavily doped ohmic contact region silicon films;

[0009] The metal lead and electrode layer are arranged on the SiO2 buried oxide layer and connected to the silicon films of each ohmic contact area;

[0010] The SiO2 isolation layer is arranged above the first silicon nanochannel, the second silicon nanochannel, the third silicon nanochannel, the ohmic contact area silicon film and the metal lead and electrode layer; the portion of the SiO2 isolation layer above the first silicon nanochannel is provided with a window, and the SiO2 gate oxide layer is provided at the window; the portion of the silicon substrate layer below the third silicon nanochannel is provided with a cavity used as a back cavity.

[0011] A further improvement of the present invention is that

[0012] The silicon substrate layer, the SiO2 buried oxide layer, the first silicon nanochannel, the ohmic contact region silicon films on both sides of the first silicon nanochannel, the metal lead and electrode layer, and the SiO2 gate oxide layer constitute a salinity sensing unit in the temperature-salinity-depth sensor;

[0013] Wherein, in the salinity sensing unit, the conductance of the first silicon nanochannel is measured, and then temperature compensation is performed to obtain salinity information.

[0014] A further improvement of the present invention is that

[0015] The silicon substrate layer, the SiO2 buried oxide layer, the second silicon nanochannel, the ohmic contact region silicon films on both sides of the second silicon nanochannel, the metal lead and electrode layer and the SiO2 isolation layer constitute a temperature sensing unit in the temperature-salt depth sensor;

[0016] Wherein, in the temperature sensing unit, the temperature information is obtained by measuring the conductivity of the second silicon nanochannel and based on the pre-calibrated relationship between temperature and conductivity.

[0017] A further improvement of the present invention is that

[0018] The SiO2 buried oxide layer, the third silicon nanochannel, the ohmic contact region silicon films on both sides of the third silicon nanochannel, the metal lead and electrode layer and the SiO2 isolation layer constitute a depth sensing unit in the temperature-salt depth sensor;

[0019] Wherein, in the depth sensing unit, the resistivity of the third silicon nanochannel is measured and then temperature compensation is performed to obtain the depth information.

[0020] A further improvement of the present invention is that

[0021] The first silicon nanochannel, the second silicon nanochannel and the third silicon nanochannel all have a crystal orientation of <100> , made of P-type single crystal silicon with a resistivity of 0.1 Ω·cm~0.5 Ω·cm and a thickness of 40 nm~200 nm;

[0022] Wherein, the P-type impurities of the P-type single crystal silicon are boron impurities or indium impurities.

[0023] A further improvement of the present invention is that

[0024] The doping concentration of P-type impurities in the ohmic contact region silicon film is greater than or equal to 5*10 19 / cm 3 .

[0025] A further improvement of the present invention is that

[0026] The SiO2 isolation layer is formed by low-pressure chemical vapor deposition and has a thickness of 100 nm to 300 nm.

[0027] A further improvement of the present invention is that

[0028] The SiO2 gate oxide layer is formed by low-pressure chemical vapor deposition and has a thickness of 10 nm to 50 nm.

[0029] A further improvement of the present invention is that

[0030] The thickness of the SiO2 buried oxide layer is 2 μm to 6 μm.

[0031] In a second aspect of the present invention, a method for manufacturing a temperature-salinity-depth sensor based on a silicon nanochannel is provided. The method for manufacturing a temperature-salinity-depth sensor based on a silicon nanochannel comprises the following steps:

[0032] Obtaining a fabrication substrate; wherein the fabrication substrate comprises a silicon substrate layer, a SiO2 buried oxide layer disposed on the silicon substrate layer, and a device layer disposed on the SiO2 buried oxide layer;

[0033] On the device layer, a barrier layer is formed by low-pressure chemical vapor deposition; on the barrier layer, an ohmic contact region diffusion window is formed by ultraviolet exposure photolithography; based on the ohmic contact region diffusion window, a heavy doping injection is performed to form an ohmic contact region;

[0034] A buffered oxide etching solution is used to etch away the barrier layer outside the ohmic contact region to obtain an exposed device layer; on the exposed device layer, a first silicon nanochannel, a second silicon nanochannel and a third silicon nanochannel are formed by photolithography; wherein both sides of the first silicon nanochannel, the second silicon nanochannel and the third silicon nanochannel are heavily doped ohmic contact region silicon films;

[0035] Forming metal leads and electrode layers on the SiO2 buried oxide layer by photolithography of metal patterns, magnetron sputtering, and stripping of metal with a stripping solution; wherein the metal leads and metal leads in the electrode layer form an alloy with the ohmic contact region;

[0036] A SiO2 isolation layer is formed by low-pressure chemical vapor deposition above the first silicon nanochannel, the second silicon nanochannel, the third silicon nanochannel, the ohmic contact region silicon film, the metal lead and the electrode layer; a window is provided at the portion of the SiO2 isolation layer above the first silicon nanochannel, and a SiO2 gate oxide layer is grown on the front side of the window by low-pressure chemical vapor deposition;

[0037] The portion of the silicon substrate layer below the third silicon nanochannel is etched into a cavity; wherein the etching stops at the SiO2 buried oxide layer to form a back cavity.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] In view of the problems of complex structure and large volume of the existing traditional temperature-salinity-depth sensors, the present invention specifically discloses a temperature-salinity-depth sensor based on silicon nanochannels, which detects temperature, salinity and depth based on transistor sensors with silicon nanochannels, and has the advantages of small size and easy operation. In addition, in view of the problems of low consistency, low sensitivity and low integration faced by the existing traditional temperature-salinity-depth sensors, the temperature-salinity-depth sensor of the present invention integrates the three sensors of temperature, salinity and depth into a single chip, and can detect parameter information such as temperature, salinity and depth by analyzing the changes in carrier concentration and mobility of the first silicon nanochannel, the second silicon nanochannel and the third silicon nanochannel; wherein, the changes in carrier concentration and mobility are exponential, and have higher sensitivity and smaller volume than the existing temperature-salinity-depth sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 is a schematic cross-sectional structure diagram of a temperature-salinity-depth sensor based on silicon nanochannels in an embodiment of the present invention;

[0042] Figure 2 is a schematic diagram of a top view structure of a temperature-salinity-depth sensor based on silicon nanochannels in an embodiment of the present invention;

[0043] The explanation of the reference numerals in the figure is as follows:

[0044] 1. Silicon substrate layer; 2. SiO2 buried oxide layer; 3. First silicon nanochannel; 4. Ohmic contact area silicon film; 5. Metal lead and electrode layer; 6. SiO2 isolation layer; 7. SiO2 gate oxide layer; 8. Second silicon nanochannel; 9. Third silicon nanochannel;

[0045] 100. Salinity sensing unit; 200. Temperature sensing unit; 300. Depth sensing unit. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments and technical solutions are only part of the embodiments of the present invention, not all of the embodiments.

[0047] All other embodiments obtained by those of ordinary skill in the art without creative work based on the technical solutions disclosed in the embodiments of the present invention belong to the scope of protection of the present invention. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] See also Figure 1 and Figure 2In an embodiment of the present invention, a temperature-salinity-depth sensor based on a silicon nanochannel is disclosed, which specifically includes: a silicon substrate layer 1, a SiO2 buried oxide layer 2, a first silicon nanochannel 3, a second silicon nanochannel 8, a third silicon nanochannel 9, an ohmic contact region silicon film 4, a metal lead and electrode layer 5, a SiO2 isolation layer 6 and a SiO2 gate oxide layer 7; wherein,

[0049] The SiO2 buried oxide layer 2 is arranged on the silicon substrate layer 1;

[0050] The first silicon nanochannel 3, the second silicon nanochannel 8 and the third silicon nanochannel 9 are arranged on the SiO2 buried oxide layer 2, and both sides of the first silicon nanochannel 3, the second silicon nanochannel 8 and the third silicon nanochannel 9 are heavily doped ohmic contact region silicon films 4;

[0051] The metal lead and electrode layer 5 are arranged on the SiO2 buried oxide layer 2 and connected to each ohmic contact region silicon film 4;

[0052] The SiO2 isolation layer 6 is disposed above the first silicon nanochannel 3, the second silicon nanochannel 8, the third silicon nanochannel 9, the ohmic contact region silicon film 4 and the metal lead and electrode layer 5; explanatoryly, the SiO2 isolation layer 6 is used as a protective layer;

[0053] The portion of the SiO2 isolation layer 6 above the first silicon nanochannel 3 is provided with a window, and the SiO2 gate oxide layer 7 is provided at the window; the portion of the silicon substrate layer 1 below the third silicon nanochannel 9 is provided with a cavity used as a back cavity.

[0054] In the silicon nanochannel-based temperature-salinity-depth sensor disclosed in an embodiment of the present invention, by analyzing the changes in carrier concentration and mobility of the first silicon nanochannel, the second silicon nanochannel, and the third silicon nanochannel, parameter information such as temperature, salinity, and depth can be detected; wherein the changes in carrier concentration and mobility vary exponentially, and the sensor has higher sensitivity and smaller volume than existing temperature-salinity-depth sensors.

[0055] By way of further specific example, the temperature-salinity-depth sensor disclosed in the embodiment of the present invention is connected to a recording display through a metal lead. In addition to receiving, processing, recording and displaying various information data obtained by the sensor, the recording display can also operate the entire set of equipment. The temperature-salinity-depth sensor disclosed in the embodiment of the present invention is tied to a buoy, a ship, a water sampler or a submersible through a rope or rigging and dropped into the water body to be monitored. The recording display can be used to receive signals, and after the signal is stable, the monitoring data can be recorded and stored.

[0056] In the embodiment of the present invention, the salinity sensing unit 100 is composed of a silicon substrate layer 1, a SiO2 buried oxide layer 2, a first silicon nanochannel 3, an ohmic contact region silicon film 4, a metal lead and electrode layer 5 and a SiO2 gate oxide layer 7; in principle, the salinity sensing unit is a silicon nanochannel transistor with an exposed SiO2 gate oxide layer, and the ions in seawater can affect the surface potential of the SiO2 gate oxide layer, thereby regulating the mobility of the silicon nanochannel transistor and the surface charge of the inversion layer, and determining the conductance and source-drain current-voltage relationship of the first silicon nanochannel; at the same time, the current-voltage characteristic is also related to temperature, so the salinity information can be calculated by measuring the conductance of the first silicon nanochannel and then performing temperature compensation.

[0057] In the embodiment of the present invention, the temperature sensing unit 200 is composed of a silicon substrate layer 1, a SiO2 buried oxide layer 2, a second silicon nanochannel 8, an ohmic contact region silicon film 4, a metal lead and electrode layer 5 and a SiO2 isolation layer 6; explanatory, the conductivity of the second silicon nanochannel in the temperature sensing unit is proportional to the majority carrier concentration and the majority carrier mobility, the current-voltage characteristic is independent of salinity and depth, but is related to temperature, and its conductivity is a function related to temperature. The relationship between temperature and conductivity can be established through temperature calibration, and temperature information can be obtained.

[0058] In the embodiment of the present invention, the depth sensing unit 300 is composed of a SiO2 buried oxide layer 2, a third silicon nanochannel 9, an ohmic contact area silicon film 4, a metal lead and electrode layer 5 and a SiO2 isolation layer 6; explanatoryly, the depth sensing unit is a silicon nanochannel transistor protected by a SiO2 isolation layer located on a SiO2 buried oxide layer cavity film. The SiO2 buried oxide layer cavity film is deformed by hydrostatic pressure at different depths, resulting in stress on the silicon nanochannel transistor. The stress change will cause a significant change in the resistivity of the transistor, thereby causing its current-voltage characteristics to be related to temperature and depth. After temperature compensation, the depth information can be calculated.

[0059] In one embodiment of the present invention, the first silicon nanochannel 3, the second silicon nanochannel 8, and the third silicon nanochannel 9 all have a crystal orientation of <100> , a P-type single crystal silicon with a resistivity of 0.1 Ω·cm~0.5 Ω·cm and a thickness of 40 nm~200 nm; in the preferred technical solution, the thickness is 100 nm.

[0060] In one embodiment of the present invention, the P-type impurities of the silicon nanochannel are boron impurities or indium impurities; the ohmic contact region silicon film 4 is formed by injecting P-type impurities into the device layer silicon film, and the doping concentration is greater than 5*10 19 / cm 3 .

[0061] Furthermore, the SiO2 isolation layer 6 is formed by low-pressure chemical vapor deposition and has a thickness of 100 nm to 300 nm.

[0062] Furthermore, the SiO2 gate oxide layer 7 is formed by low pressure chemical vapor deposition and has a thickness of 10 nm to 50 nm.

[0063] Furthermore, the thickness of the cavity film of the SiO2 buried oxide layer 2 is 2 μm to 6 μm.

[0064] In an embodiment of the present invention, a method for manufacturing a temperature-salinity-depth sensor based on a silicon nanochannel is provided, comprising the following steps:

[0065] Step 1, obtaining a fabrication substrate; wherein the fabrication substrate comprises a silicon substrate layer 1, a SiO2 buried oxide layer 2 disposed on the silicon substrate layer 1, and a device layer disposed on the SiO2 buried oxide layer 2; further specifically and exemplarily, a P-type 4-inch SOI (Silicon on Insulator) is selected as the fabrication substrate, the thickness of the SiO2 buried oxide layer 2 is 3 um, the thickness of the silicon substrate layer 1 is 450 um, and the device layer adopts a crystal orientation of <100> , made of P-type single crystal silicon with a resistivity of 0.1 Ω·cm~0.5 Ω·cm and a thickness of 100 nm, and the P-type impurity is boron impurity;

[0066] Step 2: On the device layer, a barrier layer is formed by low-pressure chemical vapor deposition; on the barrier layer, ultraviolet exposure and photolithography are performed to form an ohmic contact area diffusion window; based on the ohmic contact area diffusion window, heavy doping and injection are performed to form an ohmic contact area; further specifically and exemplarily, on the device layer, a SiO2 barrier layer with a thickness of 200 nm is formed on the front side by low-pressure chemical vapor deposition, which is used as a barrier layer for the diffusion of the ohmic contact area to protect the silicon nanochannel from the subsequent heavy doping and injection, ultraviolet exposure and photolithography are performed, and the SiO2 barrier layer is etched by reactive ion etching to form an ohmic contact area diffusion window; based on the ohmic contact area diffusion window, heavy doping and injection are performed, and boron ions are injected from the front side, and the doping concentration is greater than 5*10 19 / cm 3 ; Perform high temperature annealing at 1000°C for 30 min in an annealing furnace in a nitrogen atmosphere to form an ohmic contact area;

[0067] Step 3, using a buffered oxide etching solution to corrode and remove the barrier layer outside the ohmic contact area and organically clean it to obtain an exposed device layer; on the exposed device layer, photolithography is used to form a first silicon nanochannel 3, a second silicon nanochannel 8 and a third silicon nanochannel 9; wherein both sides of the first silicon nanochannel 3, the second silicon nanochannel 8 and the third silicon nanochannel 9 are heavily doped ohmic contact area silicon films 4; further specifically and exemplarily, on the exposed device layer, photolithography is used to form a silicon nanochannel pattern, and the device layer is reactively ion etched 100 nm to form each silicon nanochannel, which is subsequently used as a sensitive unit; photolithography is used to form a metal pattern, magnetron sputtering Ti / 50 nm-Pt / 60 nm-Au / 500 nm, and the metal is stripped with a stripping solution to form a metal lead; in an annealing furnace in a nitrogen atmosphere, alloy annealing is performed at 350°C and 5 min to form an alloy with the prepared ohmic contact area;

[0068] Step 4, forming a SiO2 isolation layer 6 by low-pressure chemical vapor deposition on the first silicon nanochannel 3, the second silicon nanochannel 8, the third silicon nanochannel 9, the ohmic contact region silicon film 4 and the metal lead and electrode layer 5; a window is provided on the portion of the SiO2 isolation layer 6 above the first silicon nanochannel 3, and a SiO2 gate oxide layer 7 is grown on the front side by low-pressure chemical vapor deposition at the window; further specifically and exemplarily, the SiO2 isolation layer 6 is grown on the front side by low-pressure chemical vapor deposition, with a thickness of 200 nm, to ensure that no leakage current occurs and that the temperature sensor and the depth sensor are not affected by external ions in the water; photolithography is used to form a gate oxide pattern of the salinity sensor; the SiO2 isolation layer is etched by reactive ion etching by 200 nm to expose the silicon nanochannel of the salinity sensor; a SiO2 gate oxide layer 7 is grown on the front side by low-pressure chemical vapor deposition, with a thickness of 20 nm, to form a gate oxide layer on the silicon nanochannel of the salinity sensor;

[0069] Step 5, photolithography is used to form the metal electrode region of the temperature-salinity depth sensor, and reactive ion etching of the SiO2 isolation layer is performed to 220 nm until the etching reaches the magnetron sputtered Ti / Pt / Au metal to form the metal electrode region of the temperature-salinity depth sensor;

[0070] Step 6, etching the portion of the silicon substrate layer 1 below the third silicon nanochannel 9 into a cavity; wherein the reactive ion etching of the silicon substrate layer is 450 um, and the etching stops until the SiO2 buried oxide layer 2 is reached to form a back cavity of the depth sensor, and the preparation is completed.

[0071] In the manufacturing method of the embodiment of the present invention, the same process steps are used in the process of forming ohmic contacts, sensitive units, metal leads, etc. By changing different mask patterns and controlling the preparation processes of different sensing units, the three sensors can be integrated into a chip through the same process flow, thereby achieving high integration of the three sensors. The temperature, salinity, and depth information can be detected by analyzing the changes in carrier concentration and mobility of silicon nanochannels, thereby solving the problems of low consistency, low sensitivity, and low integration faced by existing traditional temperature-salinity-depth sensors.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A temperature-salinity-depth sensor based on silicon nanochannel, characterized in that: The temperature-salinity-depth sensor based on silicon nanochannel comprises: a silicon substrate layer (1), a SiO2 buried oxide layer (2), a first silicon nanochannel (3), a second silicon nanochannel (8), a third silicon nanochannel (9), an ohmic contact region silicon film (4), a metal lead and electrode layer (5), a SiO2 isolation layer (6) and a SiO2 gate oxide layer (7); wherein: The SiO2 buried oxide layer (2) is provided on the silicon substrate layer (1); The first silicon nanochannel (3), the second silicon nanochannel (8) and the third silicon nanochannel (9) are arranged on the SiO2 buried oxide layer (2), and both sides of the first silicon nanochannel (3), the second silicon nanochannel (8) and the third silicon nanochannel (9) are heavily doped ohmic contact region silicon films (4); The metal lead and electrode layer (5) are arranged on the SiO2 buried oxide layer (2) and are connected to each ohmic contact region silicon film (4); The SiO2 isolation layer (6) is arranged above the first silicon nanochannel (3), the second silicon nanochannel (8), the third silicon nanochannel (9), the ohmic contact region silicon film (4) and the metal lead and electrode layer (5); a window is arranged at the portion of the SiO2 isolation layer (6) above the first silicon nanochannel (3), and the SiO2 gate oxide layer (7) is arranged at the window; and a cavity used as a back cavity is arranged at the portion of the silicon substrate layer (1) below the third silicon nanochannel (9); The silicon substrate layer (1), the SiO2 buried oxide layer (2), the first silicon nanochannel (3), the ohmic contact region silicon films (4) on both sides of the first silicon nanochannel (3), the metal lead and electrode layer (5) and the SiO2 gate oxide layer (7) constitute a salinity sensing unit (100) in the temperature-salinity-depth sensor; wherein, in the salinity sensing unit (100), the conductance of the first silicon nanochannel (3) is measured and then temperature compensation is performed to obtain salinity information; The silicon substrate layer (1), the SiO2 buried oxide layer (2), the second silicon nanochannel (8), the ohmic contact region silicon films (4) on both sides of the second silicon nanochannel (8), the metal lead and electrode layer (5) and the SiO2 isolation layer (6) constitute a temperature sensing unit (200) in the temperature-salt depth sensor; wherein, in the temperature sensing unit (200), the temperature information is obtained by measuring the conductivity of the second silicon nanochannel (8) and based on the relationship between the pre-calibrated temperature and conductivity; The SiO2 buried oxide layer (2), the third silicon nanochannel (9), the ohmic contact region silicon films (4) on both sides of the third silicon nanochannel (9), the metal lead and electrode layer (5) and the SiO2 isolation layer (6) constitute a depth sensing unit (300) in the temperature-salt depth sensor; wherein, in the depth sensing unit (300), the resistivity of the third silicon nanochannel (9) is measured and then temperature compensation is performed to obtain depth information.

2. The temperature-salinity-depth sensor based on silicon nanochannel according to claim 1, characterized in that: The first silicon nanochannel (3), the second silicon nanochannel (8) and the third silicon nanochannel (9) all have a crystal orientation of <100> , made of P-type single crystal silicon with a resistivity of 0.1 Ω·cm~0.5 Ω·cm and a thickness of 40 nm~200 nm; Wherein, the P-type impurities of the P-type single crystal silicon are boron impurities or indium impurities.

3. The temperature-salinity-depth sensor based on silicon nanochannel according to claim 1, characterized in that: In the ohmic contact region silicon film (4), the doping concentration of the P-type impurities is greater than or equal to 5*10 19 / cm 3 .

4. The temperature-salinity-depth sensor based on silicon nanochannel according to claim 1, characterized in that: The SiO2 isolation layer (6) is formed by low-pressure chemical vapor deposition and has a thickness of 100 nm to 300 nm.

5. The temperature-salinity-depth sensor based on silicon nanochannel according to claim 1, characterized in that: The SiO2 gate oxide layer (7) is formed by low-pressure chemical vapor deposition and has a thickness of 10 nm to 50 nm.

6. The temperature-salinity-depth sensor based on silicon nanochannel according to claim 1, characterized in that: The thickness of the SiO2 buried oxide layer (2) is 2 μm to 6 μm.

7. A method for manufacturing a temperature-salinity-depth sensor based on silicon nanochannels according to claim 1, characterized in that: The manufacturing method of the temperature-salinity-depth sensor based on silicon nanochannel comprises the following steps: Acquire a fabrication substrate; wherein the fabrication substrate comprises a silicon substrate layer (1), a SiO2 buried oxide layer (2) disposed on the silicon substrate layer (1), and a device layer disposed on the SiO2 buried oxide layer (2); On the device layer, a barrier layer is formed by low-pressure chemical vapor deposition; on the barrier layer, an ohmic contact region diffusion window is formed by ultraviolet exposure photolithography; based on the ohmic contact region diffusion window, a heavy doping injection is performed to form an ohmic contact region; A buffered oxide etching solution is used to etch away the barrier layer outside the ohmic contact region to obtain an exposed device layer; a first silicon nanochannel (3), a second silicon nanochannel (8) and a third silicon nanochannel (9) are formed on the exposed device layer by photolithography; wherein both sides of the first silicon nanochannel (3), the second silicon nanochannel (8) and the third silicon nanochannel (9) are heavily doped ohmic contact region silicon films (4); A metal lead and an electrode layer (5) are formed on the SiO2 buried oxide layer (2) by photolithography of a metal pattern, magnetron sputtering, and stripping of the metal using a stripping liquid; wherein the metal lead in the metal lead and the electrode layer (5) forms an alloy with the ohmic contact region; A SiO2 isolation layer (6) is formed by low-pressure chemical vapor deposition above the first silicon nanochannel (3), the second silicon nanochannel (8), the third silicon nanochannel (9), the ohmic contact region silicon film (4) and the metal lead and electrode layer (5); a window is provided at the portion of the SiO2 isolation layer (6) above the first silicon nanochannel (3), and a SiO2 gate oxide layer (7) is grown on the front side of the window by low-pressure chemical vapor deposition; The portion of the silicon substrate layer (1) below the third silicon nanochannel (9) is etched into a cavity; wherein the etching stops at the SiO2 buried oxide layer (2) to form a back cavity.

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