A deformation detection micro-nano sensor and its manufacturing and detection method

Abstract

Provided is a deformation detection micro-nano sensor, wherein the sensing core (1) comprises a silicon resistance deformation sensing layer (2), an insulating layer (3), and a temperature sensing layer (4) stacked and bonded in sequence from bottom to top, wherein the silicon resistance deformation sensing layer (2) is a strip-shaped silicon piezoresistive strip (7) in a zigzag back-and-forth state formed by etching a silicon wafer doped with boron ions, and four groups of identical silicon piezoresistive strips (7) are sequentially connected to form a four-resistance bridge; wiring pads (5) are respectively provided on the bottom surface of the silicon resistance deformation sensing layer (2) and the surface of the temperature sensing layer (4); the sensing core (1) is wrapped with a flexible wrapping (6) to wrap the entire sensing core (1), and each wiring pad (5) is exposed at a corresponding position of the flexible wrapping (6) for connecting to an external power supply and an external detection circuit; a manufacturing method and a detection method thereof are also provided; the present invention utilizes the piezoresistive effect of a semiconductor to detect strain, thereby significantly improving measurement sensitivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of deformation detection and micro-nano sensors, and relates to a deformation detection micro-nano sensor and a manufacturing method and a detection method thereof. Background Art

[0002] Microstrain measurement sensor technology for ultra-high stress conditions in complex environments is of vital importance to aerospace technology, industrial control processes, and other applications requiring precision measurement. Applications such as surface strain measurement in new energy vehicle battery packs, stress monitoring of key aircraft engine components, force monitoring at critical locations on large bridges and tunnels, force measurement experiments in hypersonic wind tunnels, and parameter monitoring required for oil drilling, among other specialized applications, place stringent demands on strain gauges with smaller dimensions, higher accuracy, and greater stability. These applications are of significant importance for the manufacturing of specialized and large-scale equipment, as well as the development of large-scale infrastructure. Therefore, the independent development of key intelligent sensor technologies for high-precision measurement of micromechanical quantities under ultra-high stress is imperative.

[0003] Currently, there are three main types of strain gauges in use: metal foil strain gauges, semiconductor strain gauges, and fiber optic strain gauges. Metal foil strain gauges are the most widely used strain monitoring product on the market due to their simple structure, minimal temperature sensitivity, low cost, and stable performance. They measure strain based on the strain effect—the change in resistance of a metal resistor material with a low temperature coefficient of resistivity—when mechanically deformed by an external force. Strain measurements tailored to different environmental requirements are achieved by fabricating metal sensitive grids with specific structural layouts. However, since the strain effect is based on the resistance change caused by geometric changes in the metal sensitive grid, metal foil strain gauges have low sensitivity and are unable to meet the requirements of microstrain measurement. Semiconductor strain gauges utilize the semiconductor piezoresistive effect to detect strain, offering advantages such as low strain detection limits, high sensitivity, and high linearity. However, silicon substrates are thick and resistant to deformation, making it difficult to accurately transfer strain from the component to the sensitive grid. Furthermore, they have a low strain limit and are prone to cracking. Furthermore, carrier mobility is significantly affected by temperature, and the piezoresistive effect originates from changes in resistivity caused by changes in the lattice structure and carrier mobility under stress. Therefore, the measurement performance of semiconductor strain gauges is severely affected by temperature. However, this shortcoming can be mitigated within a certain temperature range through temperature compensation methods. Fiber optic strain gauges indirectly measure stress and strain in an object based on changes in the lightwave intensity of a light source. However, these strain gauges currently suffer from low accuracy and immature technology, and are still in the laboratory development stage.

[0004] Existing semiconductor strain gauges use silicon resistors fabricated on silicon wafers. However, silicon wafers themselves are fragile and prone to cracking, and are not easily deformed by stretching. This poses a challenge to practical strain detection applications.

[0005] MEMS (Micro Electro Mechanical System), abbreviated as microelectromechanical system, is a system that integrates microcircuits and micromechanics on a chip according to functional requirements. MEMS is based on traditional semiconductor technologies such as photolithography and etching, and incorporates ultra-precision machining to achieve miniaturization and mass production of sensors. This significantly improves sensor consistency, reduces production costs, and increases the spatial density and coverage of data detection. Currently, sensors are gradually developing towards miniaturization and integration, and MEMS sensors, with their high sensitivity and ease of integration, have become the mainstream sensor manufacturing technology. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a deformation detection micro-nano sensor manufactured using micro-nano processing technology, and a manufacturing method and a detection method thereof.

[0007] In order to solve the above technical problems, the technical solution of the deformation detection micro-nano sensor of the present invention is:

[0008] A deformation detection micro-nano sensor includes a sensing core, characterized in that the sensing core includes a silicon resistor deformation sensing layer, an insulating layer, and a temperature sensing layer stacked and bonded from bottom to top, the insulating layer separating the temperature sensing layer and the silicon resistor deformation sensing layer from each other; the silicon resistor deformation sensing layer is a strip-shaped silicon piezoresistive strip in a zigzag reciprocating state formed by etching a silicon wafer doped with boron ions, and is connected in sequence by four identical silicon piezoresistive strips to form a four-resistance bridge; the bottom surface of the silicon resistor deformation sensing layer is respectively provided with wiring pads, and the temperature sensing layer is provided with wiring pads that can be used to connect to an external detection circuit; the outside of the sensing core is wrapped with a wrapping made of flexible organic material, and the wiring pads are exposed at corresponding positions of the wrapping for respectively connecting to an external power supply and an external detection circuit.

[0009] The following is a further solution of the deformation detection micro-nano sensor of the present invention:

[0010] The silicon piezoresistive strip includes a heavily doped region and a lightly doped region. The return section of the silicon piezoresistive strip is a heavily doped region, and the long straight strips connecting the return sections are lightly doped regions, so that the resistance distribution of the silicon piezoresistive strip is uniform; the wiring pad on the bottom surface of the silicon resistor deformation sensing layer is set in the heavily doped region.

[0011] The induction core is wrapped with a flexible wrapping covering the entire induction core. The flexible wrapping covering includes a wrapping bottom wrapped under the silicon resistor deformation induction layer, a wrapping top wrapped above the temperature induction layer, and a wrapping side wrapped around the side of the induction core.

[0012] Before doping the silicon wafer with boron ions, a doped area to be used as a silicon piezoresistive strip and a non-doped area that does not serve as a functional area of ​​the silicon piezoresistive strip are first delineated, and the non-doped area is the etching object; the bottom surface of the silicon piezoresistive strip is directly attached to the bottom of the wrapping coat, and the side and top surfaces of the silicon piezoresistive strip have silicon remaining from etching, forming a silicon wrapping of the silicon piezoresistive strip.

[0013] The shapes of the insulating layer and the temperature sensing layer match those of the silicon resistive deformation sensing layer. The insulating layer is a silicon nitride film prepared on the silicon resistive deformation sensing layer using a plasma-enhanced chemical vapor deposition process and a film selectively leaving a set area using a reactive ion etching process. The temperature sensing layer is formed by depositing a layer of metal platinum on the insulating layer using a lift-off process.

[0014] The temperature sensing layer is formed by depositing a relatively thin layer of metal chromium and a relatively thick layer of metal platinum on the insulating layer body using a lift-off process;

[0015] The connection pad is a gold pad made of metal gold using a magnetron sputtering process.

[0016] In order to solve the above technical problems, the technical solution adopted by the method for manufacturing a deformation detection micro-nano sensor of the present invention is as follows:

[0017] The above-mentioned method for manufacturing a deformation detection micro-nanosensor is characterized by including the production of the silicon resistor deformation sensing layer, the production of the insulating layer, the production of the temperature sensing layer, the production of each wiring pad, and the production of a wrapping. The production of the silicon resistor deformation sensing layer uses a silicon wafer, demarcates a silicon piezoresistive strip reserved area on the silicon wafer, and performs ion implantation in the reserved area to form a lightly doped area and a heavily doped area; the method includes the following steps:

[0018] Step 1: Clean the silicon wafer and use plasma enhanced chemical vapor deposition to deposit a silicon dioxide film on the upper surface of the silicon wafer as an ion implantation buffer layer;

[0019] Step 2: Using boron ions as an ion source to perform ion implantation on the lightly doped area, controlling the lightly doped concentration, and then performing oxygen plasma treatment;

[0020] Step 3: Use boron ions as an ion source to implant ions into the heavily doped areas, control the heavy doping concentration, and then perform oxygen plasma treatment. Place the doped silicon wafer in a tube furnace for high-temperature annealing to form lightly doped and heavily doped areas, and make photolithographic ohmic contact holes between the piezoresistive strips and the aluminum metal connection lines.

[0021] Step 4: removing the silicon dioxide buffer layer by dry etching process;

[0022] Step 5: Use magnetron sputtering to form a layer of gold in a specific area of ​​the silicon substrate and connect it to the ohmic contact hole to lead out the electrical signal of the piezoresistive strip;

[0023] Step 6: Spin-coat a layer of 50 μm-150 μm thick polyimide on the upper surface of the silicon substrate. After exposure, remove the polyimide film in the metal gold pad area to obtain a polyimide flexible substrate integrated with the silicon substrate.

[0024] Step 7: Thin the silicon wafer to 50 μm-100 μm using a mechanical grinding process, and then etch the silicon wafer to 1 μm-20 μm using a KOH solution.

[0025] Step 8: Use dry etching to specifically remove the silicon in the portion where ion implantation has not been performed, leaving only the silicon resistor and piezoresistive strip and a silicon protective layer wrapped around it.

[0026] Step 9: Prepare a silicon nitride insulating film with a thickness of 300nm-500nm on the silicon resistor table by using a vapor deposition process and a reactive ion etching process.

[0027] Step 10: Using a lift-off process, a layer of metal chromium and a layer of metal platinum are deposited on the silicon nitride insulating film on the silicon resistor table to form a serpentine temperature resistor part.

[0028] Step 11: Use a lift-off process to deposit a layer of gold on the platinum metal layer of the heavily doped ohmic contact mesa to form a wiring pad to lead out a temperature sensitive signal.

[0029] Step 12: Spin-coat a layer of exposed polyimide film on the substrate obtained in the above step, and block the wiring pad area before spin-coating or remove it after spin-coating.

[0030] The following is a further solution of the method for manufacturing the deformation detection micro-nano sensor of the present invention:

[0031] The above-described method for manufacturing a deformation detection micro-nanosensor is characterized in that, in step 1, the thickness of the prepared silicon dioxide film is 60 nm; in step 2, the light doping concentration is controlled to 1.79e19 cm-3, and the junction depth is 400 nm; in step 3, the heavy doping concentration is controlled to 1.45e20 cm-3, and the junction depth is 400 nm; in step 5, the thickness of the prepared metal gold pad for forming an ohmic contact is 100 nm; the thickness of the metal chromium deposited in the adhesion layer in step 10 is 50 nm, and the thickness of the platinum resistor is 300 nm; the thickness of the metal gold pad prepared in step 11 is 100 nm; and the thickness of the polyimide film spin-coated in step 12 is approximately 2 μm.

[0032] In order to solve the above technical problems, the technical solution adopted by the deformation detection method of the present invention is:

[0033] A deformation detection method, characterized in that, when using any of the deformation detection micro-nano sensors described above for detection, the deformation detection micro-nano sensor is connected to an external circuit and firmly fixed to the detection object. The silicon resistor deformation sensing layer is connected to an external power supply via a pair of wiring pads on its bottom surface, and an excitation voltage is provided to one pair of opposite ends of a four-resistance bridge of the resistor deformation sensing layer. The silicon resistor deformation sensing layer is connected to an external voltage detection circuit via another pair of wiring pads on its bottom surface, and the temperature sensing layer is connected to an external temperature sensing circuit via a pair of wiring pads on its top surface. Degree detection circuit; when the detection object is deformed by external force impact, the other two opposite ends of the four-resistance bridge will output a voltage signal proportional to the strain, and the temperature sensing layer outputs an instant temperature signal through a pair of wiring pads thereon; the voltage signal and the temperature signal are measured, and the deformation value is calculated by conversion through a deformation detection linear relationship formula, and the deformation detection linear relationship formula includes temperature compensation calculation; before use, in an experimental environment, the deformation detection micro-nano sensor is calibrated using a detection object sample that has been accurately measured to obtain the deformation detection linear relationship formula.

[0034] The core functional component of the deformation detection micro-nano sensor of the present invention, the silicon resistor deformation sensing layer, is a sensor manufactured by using a single crystal silicon substrate, constructing the desired shape on the silicon substrate, and packaging all of them together. Since the processing technology of silicon substrates is relatively mature, sensors with excellent performance and small size can be mass-produced, greatly reducing costs. The present invention utilizes the characteristics of micro-nano optical sensors that can be made extremely small, have good process compatibility, and can be mass-produced to produce deformation detection micro-nano sensors. Utilizing the increasingly mature micro-nano manufacturing process technology, the deformation detection micro-nano sensor of the present invention can be mass-produced with low manufacturing costs and good product consistency. A feature of this sensor is that it can be mass-produced at a relatively low cost and does not require manual adjustment and matching at a later stage, making it easy to use. The deformation detection micro-nano sensors can also be used in parallel to achieve simultaneous detection in multiple locations. Compared with the method of measuring strain by using the principle of resistance change caused by changes in the geometric dimensions of metal resistors using metal strain gauges, the present invention uses the piezoresistive effect of semiconductors to detect strain, reducing the strain detection limit and significantly improving the measurement sensitivity.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention utilizes the piezoresistive effect of semiconductors to detect microstrain. The metal resistor sensitive grid on a metal foil strain gauge is replaced with a semiconductor silicon resistor. While retaining the advantages of metal strain gauges, the sensitivity is significantly improved compared to metal foil strain gauges. This also reduces the detection limit of strain measurement, enabling the detection of extremely subtle deformations under extremely high stress. Compared to metal strain gauges, which measure strain based on the principle of resistance changes caused by changes in the geometric dimensions of metal resistors, the present invention utilizes the piezoresistive effect of semiconductors to detect strain, reducing strain detection limits and significantly improving measurement sensitivity.

[0037] (2) The present invention adopts a bridge layout of a serpentine mechanical sensitive gate to improve measurement sensitivity and reduce the influence of temperature on semiconductor devices. Combined with a highly integrated temperature detection platinum resistor, it realizes temperature compensation of strain measurement and eliminates the temperature effect of semiconductor devices during operation to the greatest extent.

[0038] (3) The present invention performs heavy doping in a specific direction and a specific area to reduce the nonlinear error of device measurement.

[0039] (4) The present invention adopts MEMS technology to highly integrate platinum resistors, silicon resistor strips and flexible membranes for mechanical support and protection insulation in a multi-layer structure similar to a "sandwich", thereby achieving miniaturization and integration of sensors, easy batch production and low cost.

[0040] (5) The present invention integrates the silicon resistor unit with the polymer substrate, so that mechanical flexibility and electronic measurement can be met at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a front perspective schematic diagram of the real deformation detection micro-nano sensor of the present invention;

[0042] Figure 2 This is a three-dimensional schematic diagram of the bottom surface of the deformation detection micro-nano sensor of the present invention;

[0043] Figure 3 This is a three-dimensional schematic diagram of the front of the induction core;

[0044] Figure 4 It is a three-dimensional schematic diagram of the bottom surface of the induction core;

[0045] Figure 5 This is a schematic diagram of the separated state of the components of the induction core;

[0046] Figure 6 3D schematic diagram of the net silicon piezoresistive strip in the hidden silicon wrapping state of the silicon resistor deformation sensing layer;

[0047] Figure 7 A schematic diagram of the arrangement of heavily doped and lightly doped regions of the silicon piezoresistive strip;

[0048] Figure 8 A circuit diagram of a four-resistance bridge formed by a silicon resistor deformation sensing layer and its silicon piezoresistive strips connected to an external power supply;

[0049] Figure 9 is the circuit diagram of the strain sensor;

[0050] Figure 10 This is a schematic diagram of the temperature sensor circuit.

[0051] The parts indicated by the numbers in each figure are: 1. Sensing core; 2. Silicon resistor deformation sensing layer; 3. Insulation layer; 4. Temperature sensing layer; 5. Wiring pad; 6. Flexible wrapping; 7. Silicon piezoresistive strip; 8. Heavily doped region; 9. Lightly doped region; 10. Package bottom; 11. Package top; 12. Package side. DETAILED DESCRIPTION

[0052] The following combination Figures 1 to 8 The present invention is described in further detail with reference to the illustrated embodiments.

[0053] The deformation detection micro-nano sensor of the present invention has an appearance as follows Figure 1 、 Figure 2 As shown. Including the induction core 1, as Figure 3 、 Figure 4 、 Figure 5 As shown, the sensing core 1 includes a silicon resistance deformation sensing layer 2, an insulating layer 3, and a temperature sensing layer 4 stacked and bonded from bottom to top. The insulating layer 3 separates the temperature sensing layer 4 from the silicon resistance deformation sensing layer 2. Figure 6 、 Figure 7 As shown, the silicon resistor deformation sensing layer 2 is a strip-shaped silicon piezoresistive strip 7 formed by etching a silicon wafer doped with boron ions in a zigzag state. Four groups of identical silicon piezoresistive strips 7 are connected in sequence to form a four-resistance bridge, as shown in FIG. Figure 8 shown.

[0054] like Figure 4 、 Figure 5 As shown, the bottom surface of the silicon resistor deformation sensing layer 2 is provided with wiring pads 5. Figure 3 、 Figure 4 As shown, the temperature sensing layer 4 is provided with wiring pads 5 that can be used to connect to an external detection circuit; the sensing core 1 is wrapped with a flexible wrapping 6 made of a flexible organic material to cover the entire sensing core 1, and each wiring pad 5 is exposed at a corresponding position of the flexible wrapping 6 for connecting to an external power supply and an external detection circuit.

[0055] like Figure 7As shown, the silicon piezoresistive strip 7 includes a heavily doped region 8 and a lightly doped region 9. The return section of the silicon piezoresistive strip 7 is the heavily doped region 8, and the long straight strip connecting the return sections is the lightly doped region 9, so that the resistance distribution of the silicon piezoresistive strip 7 is uniform; the wiring pad 5 on the bottom surface of the silicon resistor deformation sensing layer 2 is set in the heavily doped region 8.

[0056] like Figure 1 、 Figure 2 As shown, the flexible wrapping 6 includes a wrapping bottom 10 wrapped under the silicon resistor deformation sensing layer 2, a wrapping top 11 wrapped above the temperature sensing layer 4, and a wrapping side 12 wrapped on the side of the sensing core 1.

[0057] like Figure 5 、 Figure 6 As shown, before the silicon wafer is doped with boron ions, a doped region for the silicon piezoresistive strip 7 and a non-doped region that does not serve as the functional area of ​​the silicon piezoresistive strip 7 are first demarcated. The non-doped region is the target of etching. The bottom surface of the silicon piezoresistive strip 7 is directly bonded to the bottom 10 of the flexible wrapping 6. The side and top surfaces of the silicon piezoresistive strip 7 have residual silicon from the etching, forming a silicon wrapping for the silicon piezoresistive strip 7. Since the bottom surface of the silicon piezoresistive strip 7 is directly bonded to the bottom 10 of the flexible wrapping 6 without the presence of the silicon wrapping, the working function of the silicon piezoresistive strip 7 is not affected. The presence of the silicon wrapping protects the other three sides of the silicon piezoresistive strip 7. The silicon resistor is made of ion-implanted silicon, while the silicon wrapping layer is ordinary single-crystal silicon. The silicon resistor and the silicon wrapping mentioned above are made of different materials. The silicon wrapping layer tightly wraps around the silicon resistor to provide protection.

[0058] like Figure 3 、 Figure 4 、 Figure 5 As shown, the shapes of the insulating layer 3 and the temperature sensing layer 4 match those of the silicon resistive deformation sensing layer 2. The insulating layer 3 is a silicon nitride thin film prepared by a plasma-enhanced chemical vapor deposition process on the solid surface of the silicon resistive deformation sensing layer 2, and a set area is selectively left using a reactive ion etching process. The temperature sensing layer 4 is formed by depositing a layer of metal platinum on the solid surface of the insulating layer 3 using a lift-off process.

[0059] The temperature sensing layer 4 is formed by depositing a relatively thin layer of metal chromium and a relatively thick layer of metal platinum on the insulating layer 3 using a lift-off process. The wiring pad 5 can be a gold pad made of metal gold using a magnetron sputtering process.

[0060] The method for fabricating a deformation detection micro-nanosensor of the present invention includes fabricating a silicon resistive deformation sensing layer 2, an insulating layer 3, a temperature sensing layer 4, bonding pads 5, and a flexible wrapping 6. The silicon resistive deformation sensing layer 2 is fabricated using a silicon wafer. A reserved area for silicon piezoresistive strips 7 is demarcated on the silicon wafer. Ions are implanted in the reserved area to form a lightly doped region 9 and a heavily doped region 8. The method includes the following steps:

[0061] Step 1: Clean the silicon wafer and use plasma enhanced chemical vapor deposition to deposit a silicon dioxide film on the upper surface of the silicon wafer as an ion implantation buffer layer;

[0062] Step 2: Use boron ions as an ion source to perform ion implantation on the lightly doped region 9 to control the lightly doped concentration, and then perform oxygen plasma treatment;

[0063] Step 3: Use boron ions as an ion source to perform ion implantation on the heavily doped region 8, control the heavy doping concentration, and then perform oxygen plasma treatment. Place the doped silicon wafer in a tube furnace for high-temperature annealing to form lightly doped and heavily doped regions 8, and make photolithographic ohmic contact holes at the connection between the piezoresistive strip and the aluminum metal.

[0064] Step 4: removing the silicon dioxide buffer layer by dry etching process;

[0065] Step 5: Use magnetron sputtering to form a layer of gold in a specific area of ​​the silicon substrate and connect it to the ohmic contact hole to lead out the electrical signal of the piezoresistive strip;

[0066] Step 6: Spin-coat a layer of 50 μm-150 μm thick polyimide on the upper surface of the silicon substrate. After exposure, remove the polyimide film in the metal gold pad area to obtain a polyimide flexible substrate integrated with the silicon substrate.

[0067] Step 7: Thin the silicon wafer to 50 μm-100 μm using a mechanical grinding process, and then etch the silicon wafer to 1 μm-20 μm using a KOH solution.

[0068] Step 8: Use dry etching to specifically remove the silicon in the portion where ion implantation has not been performed, leaving only the silicon resistor and piezoresistive strip and a silicon protective layer wrapped around it.

[0069] Step 9: Prepare a silicon nitride insulating film with a thickness of 300nm-500nm on the silicon resistor table by using a vapor deposition process and a reactive ion etching process.

[0070] Step 10: Using a lift-off process, a layer of metal chromium and a layer of metal platinum are deposited on the silicon nitride insulating film on the silicon resistor table to form a serpentine temperature resistor part.

[0071] Step 11: Use a lift-off process to deposit a layer of gold on the platinum metal layer of the heavily doped ohmic contact mesa to form a wiring pad 5 to lead out a temperature sensitive signal.

[0072] Step 12: Spin-coat a layer of exposed polyimide film on the substrate obtained in the above step, and block the wiring pad 5 area before spin-coating or remove it after spin-coating.

[0073] In step 1, the optimized thickness value of the prepared silicon dioxide film is 60nm; in step 2, the light doping concentration can be controlled at 1.79e19cm-3, and the optimized junction depth value is 400nm; in step 3, the heavy doping concentration can be controlled at 1.45e20cm-3, and the optimized junction depth value is 400nm; in step 5, the optimized thickness value of the prepared metal gold Pad for forming ohmic contact is 100nm; the optimized thickness value of the metal chromium deposition of the adhesion layer in step 10 is 50nm, and the optimized thickness value of the platinum resistor is 300nm; the optimized thickness value of the metal gold Pad prepared in step 11 is 100nm; the optimized thickness value of the polyimide film spin-coated in step 12 is about 2μm.

[0074] The deformation detection method proposed by the present invention uses any of the above deformation detection micro-nano sensors. When using the deformation detection micro-nano sensor, the deformation detection micro-nano sensor is connected to the external circuit and firmly fixed on the detection object. The silicon resistor deformation sensing layer 2 is connected to the external power supply through one pair of wiring pads 5 on its bottom surface, and an excitation voltage is provided to one pair of opposite ends of the four-resistance bridge of the resistor deformation sensing layer. The silicon resistor deformation sensing layer 2 is connected to the external voltage detection circuit through another pair of wiring pads 5 on its bottom surface, and the temperature sensing layer 4 is connected to the external temperature sensing circuit through a pair of wiring pads 5 on its top surface. Detection circuit: When the detection object is deformed by external force, the other two opposite ends of the four-resistance bridge output a voltage signal proportional to the strain, and the temperature sensing layer 4 outputs an instantaneous temperature signal via a pair of wiring pads 5 thereon. The measured voltage and temperature signals are converted using a deformation detection linear relationship to calculate the deformation value, which includes temperature compensation. Before use, the deformation detection micro-nano sensor is calibrated in an experimental environment using an accurately measured test object sample to obtain the deformation detection linear relationship. Strain represents the relative change in length, which is the ratio of the deformation to the original length dimension. It is represented by the mathematical symbol ε, i.e., ε = ΔL / L. It is dimensionless and usually expressed as a percentage.

[0075] like Figure 8As shown in the figure, during testing, terminals 1 and 3 are connected to an external circuit voltage source. Current flows from the positive electrode → 1 → R1 → 2 → R2 → 3 → the negative electrode, and then from the positive electrode → 1 → R4 → 4 → R3 → 3 → the negative electrode, forming a loop. The voltage between terminals 2 and 4 is detected by the external circuit. Different strains cause the resistance of the silicon resistor to change, resulting in a change in the voltage between terminals 2 and 4.

[0076] The detection object can be a bridge support column, a building load-bearing beam or a wind tunnel, or an aircraft or spacecraft. When its load-bearing condition or internal stress condition changes, extremely small strain will occur on its surface. At this time, the strain gauge will also deform, causing the strain gauge silicon resistance to change accordingly. The resistance change is converted into a voltage signal output through the built-in Wheatstone bridge structure of the strain gauge to achieve the purpose of measuring micro-strain.

[0077] Explanation of the principle of why the voltage detected by the connected peripheral circuit changes in direct proportion to the deformation of the component:

[0078] When the deformation sensor deforms laterally, the long, lightly doped piezoresistive strips in sections R1 and R4 also deform and widen accordingly, reducing their resistance by ΔR. Similarly, the long, lightly doped resistors in sections R2 and R3 are elongated. According to the theory of the piezoresistive effect, since the relative deformation (Δl / L) of their elongation is equal to the relative deformation (Δw / W) of the widening in sections R1 and R4, their resistance increases by the same amount ΔR.

[0079] R1, R2, R3, and R4 are varistors, U is a constant input voltage, and U0 is the output voltage of the full-bridge circuit. According to the circuit diagram, the output voltage U0 is expressed as:

[0080]

[0081] Ideally, R1 = R2 = R3 = R4 = R, so when the semiconductor strain gauge is not subjected to stress or temperature loading, the output voltage is zero. According to the piezoresistive effect, when stress is applied to the semiconductor strain gauge, the resistivity of the piezoresistor changes, and the corresponding resistance value changes. When stress is applied to the semiconductor strain gauge, assuming that R2 and R3 are in the positive stress region, the resistance becomes R2 + △R2 and R3 + △R3; if R1 and R4 are in the negative stress region, the resistance becomes R1 - △R1 and R4 - △R4. Ideally, △R1 = △R3 = △R2 = △R4 = △R, so the output voltage expression under stress is:

[0082]

[0083] As the above equation shows, the output voltage of a semiconductor strain gauge is proportional to the relative change in resistance. Under stress, the semiconductor strain gauge generates strain, causing the varistor's resistance to change proportionally. This relative change in resistance is then converted into a voltage output via a full-bridge circuit, indirectly enabling stress and strain testing.

[0084] The circuit connection of the strain sensor is as follows Figure 9 As shown in the figure, R1 to R4 represent the silicon resistors formed by the various components of the silicon resistor deformation sensing layer; Uo1 represents the microvoltage output from the left and right terminal pads 5 of the silicon resistor deformation sensing layer 2; A represents an amplifier; Uo2 represents the amplified output voltage; ADC represents the analog-to-digital converter; Dout represents the converted digital voltage; and MCU represents a single-chip microcomputer. The upper and lower terminal pads 5 of the silicon resistor deformation sensing layer 2 are connected to an external circuit voltage source, respectively. The left and right terminal pads 5 of the silicon resistor deformation sensing layer 2 serve as the bridge output terminals. The amplified voltage from amplifier A is then converted to a digital value via the ADC. The detection principle: The strain sensor portion of the present invention utilizes a Wheatstone full-bridge connection. When the object being measured is deformed by force, the resistivity of the piezoresistive strip changes, and the resistance (ρ: resistivity; L: length; S: cross-sectional area) changes accordingly. The relationship between the output voltage and input voltage of the Wheatstone full-bridge is: Thus, the relationship between the deformation caused by force and the electrical signal can be derived.

[0085] The temperature sensor circuit is connected as follows Figure 10 As shown in the figure, R1, R2, and R3 are fixed resistors, R4 is the platinum resistor formed by the temperature sensing layer 4, Uo1 represents the platinum resistor output voltage, A represents the amplifier, Uo2 represents the amplified output voltage, ADC represents the analog-to-digital conversion circuit, Dout represents the converted digital voltage, and MCU represents the microcontroller. R1-R4 form a single-arm bridge, where the resistance values ​​of R1, R2, and R3 remain constant. R4 is the platinum resistor to be measured, and its resistance changes are converted into output voltage changes. The result is obtained through the amplification circuit and the analog-to-digital conversion circuit.

[0086] The detection principle is that as temperature rises, the platinum resistance value increases proportionally, as shown by the relationship: Rt = Rt0[1 + α(t-t0)]. Here, Rt is the resistance at temperature t; Rt0 is the resistance at temperature t0 (usually t0 = 0°C); and α is the temperature coefficient. In this design, the measurement circuit consists of three fixed resistors and a platinum resistor whose resistance changes with temperature, forming a Wheatstone bridge. The relationship between the output voltage and input voltage of the Wheatstone bridge is: Where ΔR0 is the resistance change.

[0087] like Figure 9 The strain sensor circuit shown is similar to the Figure 10The parts after amplifier A in the temperature sensor circuit shown can be shared.

Claims

1. A deformation detection micro-nano sensor, comprising a sensing core (1), characterized in that: The sensing core (1) comprises a silicon resistance deformation sensing layer (2), an insulating layer (3), and a temperature sensing layer (4) which are stacked and bonded in sequence from bottom to top, wherein the insulating layer (3) separates the temperature sensing layer (4) from the silicon resistance deformation sensing layer (2) from top to bottom; the silicon resistance deformation sensing layer (2) is a strip-shaped silicon piezoresistive strip (7) in a zigzag back-and-forth state formed by etching a silicon wafer doped with boron ions, and is connected in sequence by four groups of identical silicon piezoresistive strips (7) to form a four-resistance bridge; the bottom surface of the silicon resistance deformation sensing layer (2) is respectively provided with wiring pads (5), and the temperature sensing layer (4) is provided with wiring pads (5) for connecting to an external detection circuit; the outside of the sensing core (1) is wrapped with a flexible wrapping (6) made of a flexible organic material to wrap the entire sensing core (1), and each wiring pad (5) is exposed at a corresponding position of the flexible wrapping (6). Used to connect an external power supply and an external detection circuit respectively; the silicon piezoresistive strip (7) includes a heavily doped region (8) and a lightly doped region (9), the return section of the silicon piezoresistive strip (7) is the heavily doped region (8), and the long straight strip connected between the return sections is the lightly doped region (9), so that the resistance distribution of the silicon piezoresistive strip (7) is uniform; the wiring pad (5) on the bottom surface of the silicon resistor deformation sensing layer (2) is arranged in the heavily doped region (8); the shapes of the insulating layer (3) and the temperature sensing layer (4) match the silicon resistor deformation sensing layer (2); the insulating layer (3) is a silicon nitride film prepared by a plasma-enhanced chemical vapor deposition process on the silicon resistor deformation sensing layer (2), and a set area is selectively left by a reactive ion etching process; the temperature sensing layer (4) is formed by depositing a layer of metal platinum on the insulating layer (3) using a lift-off process.

2. The deformation detection micro-nano sensor according to claim 1, characterized in that: The flexible wrapping (6) comprises a wrapping bottom (10) wrapped below the silicon resistance deformation sensing layer (2), a wrapping top (11) wrapped above the temperature sensing layer (4), and a wrapping side (12) wrapped around the side of the sensing core (1).

3. The deformation detection micro-nano sensor according to claim 1, characterized in that: Before the silicon wafer is doped with boron ions, a doped area reserved for the silicon piezoresistive strip (7) and a non-doped area not serving as a functional area of ​​the silicon piezoresistive strip (7) are first demarcated, and the non-doped area is an etching target; the bottom surface of the silicon piezoresistive strip (7) is directly attached to the bottom (10) of the flexible wrapping (6), and the side and top surfaces of the silicon piezoresistive strip (7) have silicon remaining from the etching, forming a silicon wrapping of the silicon piezoresistive strip (7).

4. The deformation detection micro-nano sensor according to claim 1, characterized in that: The temperature sensing layer (4) is formed by depositing a relatively thin layer of metal chromium and a relatively thick layer of metal platinum on the insulating layer (3) using a lift-off process.

5. The deformation detection micro-nano sensor according to claim 1, characterized in that: The wiring pad (5) is a gold pad made of metal gold using a magnetron sputtering process.

6. The method for manufacturing a deformation detection micro-nano sensor according to claim 1, wherein: The method comprises the production of the silicon resistance deformation sensing layer (2), the production of the insulating layer (3), the production of the temperature sensing layer (4), the production of each wiring pad (5), and the production of a flexible wrapping (6). The production of the silicon resistance deformation sensing layer (2) uses a silicon wafer, demarcates a silicon piezoresistive strip (7) reserved area on the silicon wafer, and performs ion implantation in the reserved area to form a lightly doped area (9) and a heavily doped area (8); and comprises the following steps: Step 1: Clean the silicon wafer and use plasma enhanced chemical vapor deposition to deposit a silicon dioxide film on the upper surface of the silicon wafer as an ion implantation buffer layer; Step 2: using boron ions as an ion source to perform ion implantation on the lightly doped region (9), controlling the lightly doped concentration, and then performing oxygen plasma treatment; Step 3: Use boron ions as an ion source to perform ion implantation on the heavily doped region (8), control the heavy doping concentration, and then perform oxygen plasma treatment; place the doped silicon wafer in a tube furnace for high-temperature annealing to form lightly doped and heavily doped regions (8), and make photolithography-ohmic contact holes at the connection lines between the piezoresistive strip and the aluminum metal; Step 4: removing the silicon dioxide buffer layer by dry etching process; Step 5: Use magnetron sputtering to form a layer of gold in a specific area of ​​the silicon substrate and connect it to the ohmic contact hole to lead out the electrical signal of the piezoresistive strip; Step 6: Spin-coat a layer of 50 μm-150 μm thick polyimide on the upper surface of the silicon substrate. After exposure, remove the polyimide film in the metal gold pad area to obtain a polyimide flexible substrate integrated with the silicon substrate. Step 7: Thin the silicon wafer to 50 μm-100 μm using a mechanical grinding process, and then etch the silicon wafer to 1 μm-20 μm using a KOH solution; Step 8: Dry etching is used to specifically remove the silicon in the portion not subjected to ion implantation, leaving only the silicon resistor and piezoresistive strip and a silicon protective layer surrounding it; Step 9: Using a vapor deposition process and a reactive ion etching process to prepare a silicon nitride insulating film with a thickness of 300 nm to 500 nm on the silicon resistor table; Step 10: Using a lift-off process, a layer of metal chromium and a layer of metal platinum are deposited on the silicon nitride insulating film on the silicon resistor table to form a serpentine temperature resistor portion; Step 11: using a lift-off process to deposit a layer of gold on the platinum metal layer of the heavily doped ohmic contact mesa to form a wiring pad (5) to lead out a temperature sensitive signal; Step 12: Spin-coat a layer of exposable polyimide film on the substrate obtained in the above step, and block the wiring pad (5) area before spin-coating or remove it after spin-coating.

7. The method for manufacturing a deformation detection micro-nano sensor according to claim 6, wherein: In step 1, the thickness of the prepared silicon dioxide film is 60 nm; in step 2, the light doping concentration control target value is 1.79×10 19 cm -3 , the junction depth is 400nm; in step 3, the target value of heavy doping concentration control is 1.45×10 20 cm -3 , the junction depth is 400nm; in step 5, the thickness of the metal gold Pad prepared to form the ohmic contact is 100nm; the thickness of the metal chromium adhesion layer deposited in step 10 is 50nm, and the thickness of the platinum resistor is 300nm; the thickness of the metal gold Pad prepared in step 11 is 100nm; the thickness of the polyimide film spin-coated in step 12 is about 2μm.

8. A deformation detection method, characterized in that: The deformation detection micro-nano sensor according to any one of claims 1 to 5 is used. When used for detection, the deformation detection micro-nano sensor is connected to an external circuit and firmly fixed on the detection object. The silicon resistance deformation sensing layer (2) is connected to an external power supply via a pair of wiring pads (5) on its bottom surface, and an excitation voltage is provided to one pair of opposite ends of the four-resistance bridge of the resistance deformation sensing layer. The silicon resistance deformation sensing layer (2) is connected to an external voltage detection circuit via another pair of wiring pads (5) on its bottom surface, and the temperature sensing layer (4) is connected to an external power supply via a pair of wiring pads (5) on its top surface. The temperature detection circuit is connected; when the detection object is deformed by the impact of external force, the other two opposite ends of the four-resistance bridge will output a voltage signal proportional to the strain, and the temperature sensing layer (4) outputs an instant temperature signal through a pair of wiring pads (5) thereon; the voltage signal and the temperature signal are measured, and the deformation value is calculated by converting the deformation detection linear relationship formula, and the deformation detection linear relationship formula has a temperature compensation calculation; before use, in an experimental environment, the deformation detection micro-nano sensor is calibrated using a detection object sample that has been accurately measured to obtain the deformation detection linear relationship formula.

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