Deformation detection integrated micro-nano sensor and manufacturing and detection method thereof

Abstract

According to the deformation detection integrated micro-nano sensor, a substrate is an SOI silicon wafer and comprises bottom layer silicon (1), a buried oxide layer (2) and top layer silicon (3) which are sequentially stacked and attached from bottom to top, a detection unit is arranged on the top layer silicon (3) and comprises a deformation detection unit (4), a temperature detection unit (5) and a vibration detection unit (6); the final detection value of the deformation takes a deformation parameter detected by the deformation detection unit (4) as basic data, and meanwhile, a temperature parameter detected by the temperature detection unit (5) and a vibration parameter detected by the vibration detection unit (6) are used for providing compensation for the deformation parameter detected by the deformation detection unit (4); the invention further provides a manufacturing method and a detection method. The piezoresistive effect of the semiconductor is used for detecting the strain, and the measurement sensitivity is remarkably improved.

Description

Technical field:

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

[0002] The micro-deformation measurement sensor technology under extremely large stress conditions in complex environments is of great significance to aerospace technology, industrial control processes and occasions requiring precise measurement. It has a wide range of applications and a huge market in the military and civilian fields. Special application environments such as surface deformation measurement of new energy vehicle battery packs, stress monitoring of key components of aircraft engines, force monitoring of key positions of large bridges and tunnels, force measurement experiments of hypersonic wind tunnel technology, and related parameter monitoring required for oil drilling have put forward strict requirements for smaller, higher-precision, and more stable deformation meters, which is of great significance for my country to get rid of the difficulties in such products, the manufacturing of special equipment and large-scale equipment, and the development of large-scale infrastructure construction. Therefore, it is imperative to independently develop key technologies of intelligent sensors for high-precision measurement of tiny mechanical quantities under extremely large stresses.

[0003] At present, the metal foil deformation sheets produced by manufacturers such as HBM and Vishay have the advantages of simple structural design, reliable performance, and are not easily affected by temperature fluctuations. However, the sensitivity factor (GF value) of these deformation sheets is only about 2. Therefore, many researchers hope to improve the sensitivity by adopting new composite sensitive materials. For example, Nazari et al. studied a flexible fiber shape sensor for detecting battery micro-deformation, which was prepared by a scalable wet spinning method and embedded with an elastomer composed of microsphere conductive particles. Through this method, the GF value was increased to 9 [Piezoresistive free-standing microfiber strain sensor for high-resolution battery thickness monitoring]. Qiu et al. used the high conductivity and liquid deformability of liquid metal (LM) to incorporate silica particles into it to form an easy-to-print LM-SiO2 composite material, and increased the GF value of the sensor to 23.91 [Deep learning-assisted printed liquid metal sensor system for wearable applications and boxing training]. However, the principle of resistance change caused by deformation in this series of composite sensitive materials has limited improvement in GF value. Sensitivity coefficient Gf = (ΔR / R) / (Δl / l). Where R = nominal instrument resistance, ΔR = change in resistance, l = length of the sample under no pressure conditions, Δl = change in sample length. The sensitivity coefficient can be mathematically proven.

[0004] Semiconductor strain gauges use the resistivity change caused by lattice changes during deformation to achieve deformation sensitivity, which can significantly improve the GF value of the deformation sensor. Kim et al. also introduced a single-crystal silicon deformation sensor and prepared a double silicon nanomembrane (SiNM), whose GF values ​​were 42.7, 28.9 and 20.8 times higher than those of traditional metal deformation sensors at 10%, 20% and 30% stretching, respectively [Ultrathin crystalline-silicon-based strain gauges with deep learning algorithms for silent speech interfaces]. Although semiconductor strain gauges have significantly improved their detection sensitivity, the temperature changes and high vibration conditions in actual structural health monitoring scenarios bring huge interference to the measurement, which seriously limits the practical application of semiconductor strain gauges. An existing invention has proposed a strain gauge based on a flexible substrate integrating a temperature platinum resistor and a silicon differential sensitive gate, such as the invention patent application filed by the applicant on March 28, 2023, entitled "A deformation detection integrated micro-nano sensor and its manufacturing and detection method", published on CN 116358404 A. It can reduce the influence of temperature effects and achieve ultra-sensitive detection of deformation measurement. However, under complex working conditions, especially under vibration conditions, high-sensitivity deformation devices have problems of poor measurement stability and low reliability. This is mainly because the vibration input will cause the silicon sensitive gate to deform, which brings difficulties to high-precision deformation measurement.

[0005] The present invention is intended to solve the above problem. The present invention integrates a vibration detection unit in a deformation device, detects vibration information while detecting deformation signals, and analyzes the vibration information to compensate for the deformation measurement results to obtain accurate deformation detection results. Summary of the invention:

[0006] The technical problem to be solved by the present invention is to provide a deformation detection micro-nano integrated sensor made by 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 integrated micro-nano sensor of the present invention is:

[0008] A deformation detection integrated micro-nano sensor comprises a substrate, characterized in that the substrate is an SOI silicon wafer, the substrate comprises a bottom silicon layer, a buried oxide layer, and a top silicon layer stacked and bonded in sequence from bottom to top, a detection unit is arranged on the top silicon layer, the detection unit comprises a deformation detection unit, in order to eliminate the interference of working environment vibration and temperature change to high-precision measurement, provide corresponding compensation for deformation detection parameters, also comprises a temperature detection unit, and also comprises a vibration detection unit; the final detection value of the deformation is based on the deformation parameter detected by the deformation detection unit, and at the same time, the temperature parameter detected by the temperature detection unit and the vibration parameter detected by the vibration detection unit are used to provide compensation for the deformation parameter detected by the deformation detection unit.

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

[0010] The deformation detection unit is a first silicon piezoresistive strip in a zigzag reciprocating state formed by a silicon wafer doped with boron ions, and is composed of four groups of identical first silicon piezoresistive strips connected in sequence to form a first four-resistance bridge; the four groups of first silicon piezoresistive strips respectively lead out conductive leads to connect to the first wiring pads, which are used to respectively connect to an external power supply and an external detection circuit.

[0011] The vibration detection unit is a second silicon piezoresistive strip in a zigzag reciprocating state formed by doping silicon wafers with boron ions, and is connected in sequence by 4 groups of identical second silicon piezoresistive strips to form a second four-resistance bridge; the 4 groups of silicon piezoresistive strips respectively lead out leads to connect to the second wiring pads, which are used to connect to an external power supply and an external detection circuit respectively; and the top silicon and buried oxide layer are formed by a wet etching process to form the following structure: including a cross beam and a mass block, wherein the silicon piezoresistive strip is arranged at the end of the cross beam, and when there is external vibration input, the vibration of the cross beam and the mass block will cause the cross beam to deform, thereby changing the resistance value of the second silicon piezoresistive strip; the 4 groups of second silicon piezoresistive strips respectively lead out conductive leads to connect to the second wiring pads, which are used to connect to an external power supply and an external detection circuit respectively; the bottom silicon is subjected to a wet etching process at the position below the cross beam and the mass block to form a suspended cavity, so that the cross beam and the mass block are suspended.

[0012] The temperature detection unit includes a temperature platinum resistor, a conductive lead and a third wiring pad arranged in a serpentine shape. It is prepared on the top silicon layer and isolated from the bottom top silicon by the insulating material silicon nitride; the third wiring pad is used to connect an external power supply and a detection circuit; the temperature platinum resistor is formed by depositing a layer of metal platinum on the insulating layer entity using a lift-off process.

[0013] The first silicon piezoresistive strip and the second silicon piezoresistive strip both include heavily doped regions and lightly doped regions. The return section of the silicon piezoresistive strip is the heavily doped region, and the long straight strips connected between the return sections are the lightly doped regions, so that the resistance distribution of the silicon piezoresistive strip is uniform. Before the silicon wafer is doped with boron ions, the doped region reserved for the silicon piezoresistive strip and the non-doped region that does not serve as the functional region of the silicon piezoresistive strip are first delineated, and the non-doped region is the etching object.

[0014] The temperature detection unit is formed by depositing a relatively thin layer of metal chromium and a relatively thick layer of metal platinum on the insulating layer entity using a lift-off process; the first wiring pad, the second wiring pad, and the third wiring pad are all gold pads made of metal gold using a magnetron sputtering process.

[0015] The deformation detection integrated micro-nano sensor uses at least half of its substrate area as a vibration detection unit area, and the remaining half area at most is used as a deformation detection unit and a temperature detection unit.

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

[0017] The manufacturing method of the deformation detection integrated micro-nano sensor described above is characterized in that it includes the manufacturing of the deformation detection unit, the formation of the insulating layer, the manufacturing of the temperature detection unit and the manufacturing of each wiring pad, demarcating the silicon piezoresistive strip reserved area on the top silicon layer, and performing ion implantation in the reserved area to form a lightly doped area and a heavily doped area; and includes the following steps:

[0018] Step 1: The first and second silicon piezoresistive strips are manufactured on a 600A thermally oxidized SOI silicon wafer using a boron ion implantation process. The implantation angle is selected between 7° and 9°, and the sheet resistance is between 72 and 90Ω. The thickness of each layer of the SOI silicon wafer is 10μm for the top silicon layer, 1μm for the buried oxide layer, and 400μm for the bottom silicon layer.

[0019] Step 2: LPCVD deposits 1500A-3000A low stress silicon nitride as an insulating layer between the subsequently prepared metal and the top silicon layer, and acts as a surface mask protection during subsequent wet etching;

[0020] Step 3, using a Cr / Pt / Au metal film prepared by a magnetron sputtering process and patterning the metal using an ion beam etching (IBE) process to form a temperature detection unit and a third wiring pad;

[0021] Step 4: Using plasma chemical vapor deposition (PECVD) to deposit 1500A-3000A of silicon nitride (Si3N4) as an insulating layer for the temperature detection unit and interconnection leads;

[0022] Step 5: Reactive ion etching (RIE) is used to remove the silicon nitride (Si3N4) insulating layer on the surface of each wiring pad to expose each wiring pad;

[0023] Step 6: Use reactive ion etching (RIE) to etch 3000A-6000A of surface silicon nitride (Si3N4); use deep etching (DRIE) to etch 10μm of top silicon; use reactive ion etching (RIE) to etch 1μm of buried oxide layer to achieve precise patterning of the cross beam-mass block;

[0024] Step 7: Prepare a 2000A thick silicon nitride (Si3N4) wet etching sidewall mask by plasma chemical vapor deposition (PECVD);

[0025] Step 8: Etch 2000A thick silicon nitride (Si3N4) by maskless reactive ion etching (RIE) process, leaving the composite mask layer of the side wall, open the anisotropic etching window, and accurately form the beam-mass block structure by wet etching process;

[0026] Step 9: Finally, the silicon wafer is thinned to 200 μm-300 μm using chemical mechanical polishing (CMP).

[0027] The following is a further solution of the method for manufacturing the deformation detection integrated micro-nano sensor of the present invention:

[0028] The manufacturing method of the above-mentioned deformation detection integrated micro-nano sensor is characterized in that:

[0029] In step 1, the thickness of thermal oxidation is preferably 600 Å, the ion implantation energy is preferably 40 keV, the incident angle is 7°, and the heavily doped sheet resistance is about 2 Ω and the lightly doped sheet resistance is about 80 Ω;

[0030] In step 2, preferably LPCVD (low pressure chemical vapor deposition) is used to deposit 3000A low stress silicon nitride;

[0031] In step 3, the thickness of the Cr / Pt / Au metal film is preferably 500A / 3000A / 500A, the metal line width of the temperature sensitive unit is preferably 15 μm, and the size of the third wiring pad is 1mm*1mm;

[0032] In step 4, 3000A of silicon nitride is preferably deposited using a plasma chemical vapor deposition process (PECVD);

[0033] In step 5, the depth of etching silicon nitride is preferably 3000 Å, which is consistent with the deposition thickness in step S4;

[0034] In step 6, the thickness of the surface silicon nitride is preferably etched to 6000 Å;

[0035] In step 9, the thickness of the silicon wafer thinned is preferably 250 μm.

[0036] In order to solve the above technical problems, the technical solution adopted by the deformation detection method of the present invention is:

[0037] A deformation detection method, characterized in that any one of the above-mentioned integrated micro-nano sensors for deformation detection is used. When used for detection, the integrated micro-nano sensor for deformation detection is connected to an external circuit, and the integrated micro-nano sensor for deformation detection is firmly fixed on the detection object; when used, a pair of wiring pads 3 in the deformation detection unit is connected to an external power supply to provide an excitation voltage for one pair of opposite ends of a four-resistance bridge, and another pair of wiring pads 3 of the deformation detection unit is connected to an external voltage detection circuit; similarly, when used, a pair of wiring pads in a vibration detection unit is connected to an external power supply to provide an excitation voltage for one pair of opposite ends of a four-resistance bridge, and another pair of wiring pads is connected to an external voltage detection circuit; the temperature detection unit is connected to an external temperature detection circuit via a pair of wiring pads 2 thereon; when the detection object is deformed by an external force impact, The other pair of opposite ends of the four-resistance bridge of the deformation detection unit will output a voltage signal proportional to the deformation amount, the temperature detection unit outputs an instant temperature signal through a pair of wiring pads 5 thereon, and the other pair of opposite ends of the four-resistance bridge of the vibration detection unit outputs a voltage signal reflecting the current vibration condition of the object under test; the relevant electrical signals of the three measured physical parameters are mathematically converted to eliminate the interference of temperature and vibration on deformation detection, and the accurate deformation value is calculated; before use, in an experimental environment, the deformation detection integrated micro-nano sensor is calibrated with a sample of the detection object that has been accurately measured to obtain the deformation detection linear relationship; the deformation represents the relative change in length, which is the ratio of the deformation amount to the original length dimension, and is represented by the mathematical symbol ε, that is, ε=ΔL / L, dimensionless, and usually expressed as a percentage.

[0038] The deformation detection integrated micro-nano sensor of the present invention has a substrate of an SOI silicon wafer, including a bottom silicon layer, a buried oxide layer, and a top silicon layer stacked and bonded from bottom to top. A detection unit is arranged on the top silicon layer. The detection unit includes a deformation detection unit. In order to eliminate the interference of working environment vibration and temperature change to high-precision measurement, compensation is provided for the deformation detection signal. It also includes a temperature detection unit and a vibration detection unit.

[0039] The deformation detection integrated micro-nano sensor of the present invention proposes to use the method of simultaneously measuring the three parameters of deformation, vibration and temperature to achieve the purpose of accurate deformation measurement under wide temperature range and high vibration conditions for deformation detection conditions with high vibration and large temperature change. The present invention proposes a micro deformation sensor for integrated in-situ detection of deformation, vibration and temperature parameters and a preparation method thereof. The present invention proposes a signal processing method for data fusion and decoupling of the three parameters of deformation, vibration and temperature under wide temperature range and high vibration conditions for the three-parameter integrated sensor. The present invention can solve the problem of high-precision deformation detection difficulty under high vibration and large temperature drift conditions; the present invention adopts MEMS technology for batch manufacturing, and the sensor is miniaturized and low-cost; the present invention integrates the detection of vibration and temperature parameters that affect deformation detection into a sensor, realizes the high integration of multiple sensitive units, and real-time measurement of multiple parameters in situ, and further improves the deformation measurement accuracy through multi-parameter data fusion.

[0040] The deformation detection integrated micro-nano sensor of the present invention uses an SOI (silicon on insulator) substrate as a preparation substrate and adopts a MEMS batch manufacturing process. Three parameter detection units are arranged on the integrated micro-nano sensor: a deformation detection unit, a temperature detection unit, and a vibration detection unit. The detection data of the deformation detection unit is compensated by the temperature detection unit and the vibration detection unit, which can significantly improve the sensitivity and accuracy of deformation detection under temperature changes and vibration environments. The accompanying drawings of the specification of the present invention provide one of the layout methods that can be used as a reference, that is, the deformation, temperature, and vibration units are arranged in sequence from right to left. Through real-time in-situ detection of deformation, vibration, and temperature signals, temperature compensation and vibration compensation for deformation measurement are completed, and high-precision real-time detection of tiny deformations under large temperature fluctuations and high vibration conditions is achieved.

[0041] When using the sensor, fix the sensor firmly on the detection object, and connect the wires from the pad to the back-end signal acquisition circuit to transmit the sensing signal.

[0042] The vibration detection unit of the deformation detection integrated micro-nano sensor of the present invention is composed of a square mass block and a support beam, on which a serpentine piezoresistive strip (formed by an ion implantation process) is arranged, and the serpentine piezoresistive strips on the four beams are connected in series in sequence to form a full-bridge structure. When in use, the relative wiring pads on the unit are connected to an external circuit to provide an excitation voltage for it, and a pair of wiring pads at the other two ends of the bridge are connected to an external voltage detection circuit. When there is an external vibration input, the support beam will move with the vibration of the mass block, and then deform, causing the piezoresistive resistance value to change, and the design of the full bridge can convert the resistance change into a voltage change and transmit it out. In summary, we can obtain the vibration information of the current object under test by analyzing the voltage change signal.

[0043] The temperature detection unit of the deformation detection integrated micro-nano sensor of the present invention is composed of a serpentine platinum resistor, and has two pads to lead out signals to the resistance detection circuit for measurement. The platinum resistor is a temperature-sensitive material, and its resistance is in a positive linear relationship with the temperature. The temperature value to be measured can be inferred by detecting the resistance of the platinum resistor. The serpentine platinum resistor is integrated and stacked in a certain area in the deformation detection unit, and silicon nitride insulating materials are provided above and below to ensure electrical isolation of the platinum resistor from the substrate and the outside world.

[0044] The deformation detection unit of the deformation detection integrated micro-nano sensor of the present invention is composed of four serpentine piezoresistive strips with completely identical geometric dimensions and arranged in series in different directions (laid flat on the plane of the functional area, and arranged along the single crystal silicon <110> Crystal direction), forming a full-bridge structure. When used for detection, the relative wiring pads on the unit are connected to an external circuit to provide an excitation voltage, and the other pair of wiring pads at the other ends of the bridge are connected to an external voltage detection circuit. When the object to be tested is deformed, the deformation detection unit will be deformed accordingly, which will cause the piezoresistance value to change. The full-bridge structure can output the change in piezoresistance value in the form of voltage change, so the deformation information of the current object to be tested can be obtained by analyzing the voltage signal.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. Significantly improve the sensitivity and accuracy of deformation detection under temperature changes and vibration environments.

[0047] 2. When there is external vibration input, the support beam will move with the vibration of the mass block, and then deform, causing the piezoresistance value to change. The full-bridge design can convert the resistance change into a voltage change and transmit it out. Vibration factor compensation for strain measurement is achieved, and the vibration effect of semiconductor devices during operation is eliminated to the greatest extent.

[0048] 3. The bridge layout of the serpentine mechanical sensitive gate is adopted to improve the measurement sensitivity and reduce the influence of temperature on semiconductor devices. Combined with the highly integrated temperature detection platinum resistor, the temperature compensation of strain measurement is realized to eliminate the temperature effect of semiconductor devices when they are working to the greatest extent.

[0049] 4. The miniaturization and integration of sensors are realized, which makes them easy to mass produce and low in cost. Description of the drawings:

[0050] Figure 1 This is a front perspective schematic diagram of the integrated micro-nano sensor for deformation detection of the present invention;

[0051] Figure 2 This is a three-dimensional schematic diagram of the bottom surface of the deformation detection integrated micro-nano sensor of the present invention;

[0052] Figure 3This is a schematic diagram of the hypothetical separation state of the components of the deformation detection integrated micro-nano sensor of the present invention;

[0053] Figure 4 It is a schematic diagram of a top view of each detection unit arranged on the top silicon layer;

[0054] Figure 5 It is a plane schematic diagram of the arrangement of the heavily doped region and the lightly doped region of the silicon piezoresistive strip of the deformation detection unit;

[0055] Figure 6 A circuit diagram of the deformation detection unit with a four-resistance bridge formed by its silicon piezoresistive strips and an external power supply state;

[0056] Figure 7 A schematic diagram of connecting the deformation detection unit to an external detection circuit;

[0057] Figure 8 A schematic diagram of connecting the temperature detection unit to an external detection circuit;

[0058] Fig. 9 Schematic diagram of connecting the vibration detection unit to the external detection circuit.

[0059] The parts indicated by the numbers in each figure are: 1. bottom silicon; 2. buried oxide layer; 3. top silicon; 4. deformation detection unit; 5. temperature detection unit; 6. vibration detection unit; 7. first silicon piezoresistive strip; 8. first wiring pad; 9. second silicon piezoresistive strip; 10. second wiring pad; 11. cross beam; 12. mass block; 13. temperature platinum resistor; 14. third wiring pad; 15. heavily doped region; 16. lightly doped region; 17. suspended cavity. Specific implementation method:

[0060] The following combination Figures 1 to 9 The present invention is described in further detail with reference to the illustrated embodiments.

[0061] The present invention provides an integrated micro-nano sensor for deformation detection, such as Figure 1 , Figure 2 As shown, it includes a substrate, which includes a bottom silicon 1, a buried oxide layer 2, and a top silicon 3 which are stacked and bonded in sequence from bottom to top. A detection unit is arranged on the top silicon 3, and the detection unit includes a deformation detection unit 4. In order to eliminate the interference of working environment vibration and temperature change to high-precision measurement, corresponding compensation is provided for deformation detection parameters. It also includes a temperature detection unit 5 and a vibration detection unit 6. The final detection value of the deformation is based on the deformation parameter detected by the deformation detection unit 4, and the temperature parameter detected by the temperature detection unit 5 and the vibration parameter detected by the vibration detection unit 6 are used to compensate for the deformation parameter detected by the deformation detection unit 4.

[0062] like Figure 1 , Figure 4 As shown, the deformation detection unit 4 is a first silicon piezoresistive strip 7 in a zigzag reciprocating state formed by a silicon wafer doped with boron ions, and is connected in sequence by 4 groups of identical first silicon piezoresistive strips 7 to form a first four-resistance bridge; the 4 groups of first silicon piezoresistive strips 7 respectively lead out conductive leads to connect to the first wiring pads 8, which are used to respectively connect to an external power supply and an external detection circuit.

[0063] like Figure 1 , Figure 4 As shown, the vibration detection unit 6 is a strip-shaped second silicon piezoresistive strip 9 in a zigzag reciprocating state formed by doping silicon wafers with boron ions, and is connected in sequence by 4 groups of identical second silicon piezoresistive strips 9 to form a second four-resistance bridge; the 4 groups of silicon piezoresistive strips respectively lead out leads to connect to the second wiring pads 10, which are used to connect to an external power supply and an external detection circuit respectively; and the top silicon 3 and the buried oxide layer 2 are subjected to a wet etching process to form the following structure: including a cross beam 11 and a mass block 12, wherein the silicon piezoresistive strip is arranged at the end of the cross beam 11, and when there is external vibration input, the vibration of the cross beam 11 and the mass block 12 will cause the cross beam 11 to deform, thereby changing the resistance value of the second silicon piezoresistive strip 9; the 4 groups of second silicon piezoresistive strips 9 respectively lead out conductive leads to connect to the second wiring pads 10, which are used to connect to an external power supply and an external detection circuit respectively; the bottom silicon 1 is subjected to a wet etching process at a position below the cross beam 11 and the mass block 12 to form a suspended cavity 17, so that the cross beam 11 and the mass block 12 are suspended. The circuits of the first four-resistance bridge and the second four-resistance bridge in the external power supply state are both as follows Figure 6 shown.

[0064] like Figure 1 , Figure 4 As shown, the temperature detection unit 5 includes a temperature platinum resistor 13 arranged in a serpentine shape, a conductive lead and a third wiring pad 14, which is prepared on the top silicon 3 and isolated from the bottom top silicon 3 by an insulating material silicon nitride; the third wiring pad 14 is used to connect an external power supply and a detection circuit; the temperature platinum resistor 13 is formed by depositing a layer of metal platinum on the insulating layer entity using a lift-off process.

[0065] like Figure 5 As shown, the first silicon piezoresistive strip 7 includes a heavily doped region 15 and a lightly doped region 16. The return section of the silicon piezoresistive strip is the heavily doped region 15, and the long straight strip connected between the return sections is the lightly doped region 16, so that the resistance distribution of the silicon piezoresistive strip is uniform. The second silicon piezoresistive strip 9 is the same. Before the silicon wafer is doped with boron ions, the doped region reserved as the silicon piezoresistive strip and the non-doped region not serving as the functional region of the silicon piezoresistive strip are first demarcated, and the non-doped region is the etching object.

[0066] like Figure 1 , Figure 4As shown, the temperature detection unit 5 is formed by depositing a relatively thin layer of metal chromium and a relatively thick layer of metal platinum on the insulating layer entity using a lift-off process; the first wiring pad 8, the second wiring pad 10, and the third wiring pad 14 are all gold pads made of metal gold using a magnetron sputtering process.

[0067] The deformation detection integrated micro-nano sensor uses at least half of its substrate area as the vibration detection unit 6 area, and the remaining half area at most is used as the deformation detection unit 4 and the temperature detection unit 5.

[0068] The manufacturing method of the deformation detection integrated micro-nano sensor of the present invention includes the manufacturing of the deformation detection unit 4, the formation of the insulating layer, the manufacturing of the temperature detection unit 5 and the manufacturing of each wiring pad, demarcating the silicon piezoresistive strip reserved area on the top silicon 3, and performing ion implantation in the reserved area to form a lightly doped area 16 and a heavily doped area 15; and includes the following steps:

[0069] Step 1: The first silicon piezoresistive strip 7 and the second silicon piezoresistive strip 9 are manufactured on a 600A thermally oxidized SOI silicon wafer by using a boron ion implantation process. The implantation angle is selected between 7° and 9°, and the sheet resistance is between 72 and 90Ω. The thickness of each layer of the SOI silicon wafer is 310μm for the top silicon, 21μm for the buried oxide layer, and 1400μm for the bottom silicon.

[0070] Step 2: LPCVD deposits 1500A-3000A low stress silicon nitride as an insulating layer between the subsequently prepared metal and the top silicon 3, and acts as a surface mask protection during subsequent wet etching;

[0071] Step 3: Using a Cr / Pt / Au metal film prepared by a magnetron sputtering process and patterning the metal using an ion beam etching (IBE) process to form a temperature detection unit 5 and a third wiring pad 14;

[0072] Step 4: using plasma chemical vapor deposition (PECVD) to deposit 1500A-3000A of silicon nitride (Si3N4) as an insulating layer for the temperature detection unit 5 and the interconnection leads;

[0073] Step 5: Reactive ion etching (RIE) is used to remove the silicon nitride (Si3N4) insulating layer on the surface of each wiring pad to expose each wiring pad;

[0074] Step 6: Use reactive ion etching (RIE) to etch 3000A-6000A of surface silicon nitride (Si3N4); use deep etching (DRIE) to etch 10μm of top silicon 3; use reactive ion etching (RIE) to etch 1μm of buried oxide layer 2 to achieve precise patterning of cross beam 11-mass block 12;

[0075] Step 7: Prepare a 2000A thick silicon nitride (Si3N4) wet etching sidewall mask by plasma chemical vapor deposition (PECVD);

[0076] Step 8: Etch 2000A thick silicon nitride (Si3N4) by maskless reactive ion etching (RIE) process, leaving the composite mask layer of the side wall, open the anisotropic etching window, and accurately form the beam-mass block 12 structure by wet etching process;

[0077] Step 9: Finally, the silicon wafer is thinned to 200 μm-300 μm using chemical mechanical polishing (CMP).

[0078] Furthermore, in step 1, the thickness of thermal oxidation is preferably 600 Å, the ion implantation energy is preferably 40 keV, the incident angle is 7°, and the heavily doped sheet resistance is about 2 Ω and the lightly doped sheet resistance is about 80 Ω;

[0079] In step 2, preferably LPCVD (low pressure chemical vapor deposition) is used to deposit 3000A low stress silicon nitride;

[0080] In step 3, the thickness of the Cr / Pt / Au metal film is preferably 500A / 3000A / 500A, the metal line width of the temperature sensitive unit is preferably 15 μm, and the size of the third wiring pad 14 is 1 mm*1 mm;

[0081] In step 4, 3000A of silicon nitride is preferably deposited using a plasma chemical vapor deposition process (PECVD);

[0082] In step 5, the depth of etching silicon nitride is preferably 3000 Å, which is consistent with the deposition thickness in step S4;

[0083] In step 6, the thickness of the surface silicon nitride is preferably etched to 6000 Å;

[0084] In step 9, the thickness of the silicon wafer thinned is preferably 250 μm.

[0085] The deformation detection integrated micro-nano sensor of the present invention is connected to an external circuit when used for detection. Figure 7 As shown, the deformation detection integrated micro-nano sensor is firmly fixed on the detection object. When in use, a pair of wiring pads 3 in the deformation detection unit 4 is connected to an external power supply to provide an excitation voltage for one pair of opposite ends of the four-resistance bridge, and another pair of wiring pads 3 of the deformation detection unit 4 is connected to an external voltage detection circuit. Similarly, Fig. 9 As shown, when in use, a pair of connection pads in the vibration detection unit 6 is connected to an external power source to provide an excitation voltage to one pair of opposite ends of the four-resistance bridge, and the other pair of connection pads is connected to an external voltage detection circuit. Figure 8 As shown, the temperature detection unit 5 is connected to an external temperature detection circuit via a pair of wiring pads 2 on it. When the detection object is deformed by external force impact, the other two opposite ends of the four-resistance bridge of the deformation detection unit 4 will output a voltage signal proportional to the deformation amount, the temperature detection unit 5 outputs an instant temperature signal via a pair of wiring pads 5 on it, and the other two opposite ends of the four-resistance bridge of the vibration detection unit 6 output a voltage signal reflecting the vibration of the current object under test; the relevant electrical signals of the three measured physical parameters are mathematically converted to eliminate the interference of temperature and vibration on deformation detection, and calculate the accurate deformation value; before using the detection, in an experimental environment, the deformation detection integrated micro-nano sensor is calibrated with a sample of the detection object that has been accurately measured to obtain a linear relationship for deformation detection; the deformation represents the relative change in length, which is the ratio of the deformation amount to the original length size, represented by the mathematical symbol ε, that is, ε=ΔL / L, dimensionless, usually expressed as a percentage.

[0086] The deformation detection unit and the vibration detection unit both adopt the piezoresistive principle and are designed with a Wheatstone bridge structure. Figure 6 As shown, when testing, terminals 1 and 3 are connected to an external circuit voltage source, and the current flows through positive electrode → 1 → R1 → 2 → R2 → 3 → negative electrode and positive electrode → 1 → R4 → 4 → R3 → 3 → negative electrode to form a loop. The voltage between terminals 2 and 4 is detected by an external circuit. Different strains will cause the resistance of the silicon resistor to change, causing the voltage between terminals 2 and 4 to change. The strain of the deformation detection unit is input from the outside, that is, the device deforms following the detection object, and the deformation on the cross beam 6 of the vibration detection unit comes from the input vibration. The mass block 7 will vibrate with the vibration of the detection object, thereby driving the deformation of the cross beam, and the vibration is detected by detecting the deformation of the cross beam.

[0087] 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 deform accordingly, 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.

[0088] Explanation of the principle of why the voltage detected by the connected peripheral circuit changes in direct proportion to the deformation of the component:

[0089] When the deformation detection sensor is deformed laterally, the long straight lightly doped piezoresistive strips in R1 and R4 will also be deformed accordingly and become wider, and their resistance value will decrease by ΔR. Similarly, the long straight lightly doped resistors in R2 and R3 will be elongated accordingly. According to the piezoresistive effect theory, since the relative deformation value (Δl / L) of the elongation is equal to the relative deformation value (Δw / W) of the widening in R1 and R4, their resistance value will increase by the same value ΔR.

[0090] 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:

[0091]

[0092] Ideally, R1=R2=R3=R4=R, so when the semiconductor strain gauge is not subjected to stress and temperature loading, the output voltage is zero. According to the piezoresistive effect, when stress is loaded on the semiconductor strain gauge, the resistivity of the varistor changes, and the corresponding resistance value changes. When stress is loaded on the semiconductor strain gauge, assuming that R2 and R3 are in the positive stress area, the resistance becomes R2+△R2 and R3+△R3; R1 and R4 are in the negative stress area, then the resistance becomes R1-△R1 and R4-△R4. Ideally, △R1=△R3=△R2=△R4=△R, then the output voltage expression under stress is:

[0093]

[0094] It can be seen from the above formula that the output voltage of the semiconductor strain gauge is proportional to the relative change of resistance. Under the action of stress, the semiconductor strain gauge produces strain, causing the resistance value of the varistor to change proportionally; then the relative change of resistance is converted into voltage output through the full-bridge circuit, thereby indirectly realizing the stress and strain test.

[0095] The circuit connection of the strain sensor is as follows: Figure 7As shown in the figure, R1 to R4 are silicon resistors formed by various parts of the silicon resistor deformation sensing layer; Uo1 represents the micro voltage outputted by the left and right terminal wiring pads 5 of the silicon resistor deformation sensing layer 2; A represents an amplifier; Uo2 represents the amplified output voltage, ADC represents an analog-to-digital conversion circuit, Dout represents the converted digital voltage, and MCU represents a single-chip microcomputer, wherein the upper and lower terminal wiring pads 5 of the silicon resistor deformation sensing layer 2 are respectively connected to an external circuit voltage source, and the left and right terminal wiring pads 5 of the silicon resistor deformation sensing layer 2 are bridge output ends, and the circuit connected to the ADC after amplification by the amplifier A is converted into a digital quantity. Its detection principle: The strain sensor part in the design of the present invention adopts the Wheatstone full bridge method. When the object to be measured is deformed by force, the resistivity of the piezoresistive strip will change, because the resistance (ρ: resistivity; L: length; S: cross-sectional area), and its resistance value changes accordingly. The relationship between the output voltage and input voltage of the Wheatstone full bridge is, so that the relationship between the deformation caused by force and the electrical signal can be obtained.

[0096] Explanation of the principle of why the voltage detected by the connected peripheral circuit is related to the vibration information of the component:

[0097] When the mass block 7 vibrates with external working conditions, the cross beam 6 will be deformed, resulting in a change in the resistance value of the varistor 5 on the cross beam. The longitudinal piezoresistors R1 and R will be deformed accordingly and become wider, and their resistance value will decrease by ΔR. Similarly, the long straight lightly doped resistors in the two lateral parts R2 and R3 will be elongated accordingly. According to the theory of piezoresistive effect, since the relative deformation value (Δl / L) of the elongation is equal to the relative deformation value (Δw / W) of the widening of the R1 and R4 parts, their resistance value will increase by the same value ΔR.

[0098] 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:

[0099]

[0100] It can be seen that the output voltage reflects the vibration information of the test piece.

[0101] When using the detection, the deformation detection micro-nano sensor is connected to the external circuit, the deformation detection micro-nano sensor is firmly fixed on the detection object, the deformation detection unit is connected to the external power supply through a pair of relative wiring pads, an excitation voltage is provided to one pair of opposite ends of the strain sensing four-resistance bridge, and a pair of wiring pads at the other two ends of the bridge are connected to the external voltage detection circuit; there are four pads on the vibration sensing unit, one pair of opposite wiring pads is connected to the external power supply to provide an excitation voltage, and the other end is connected to the voltage detection circuit, so that a voltage signal matching the vibration physical information can be obtained, and then the vibration signal value can be deduced; the temperature detection unit 5 is connected to the external temperature detection circuit through a pair of wiring pads on it, so that a resistance value matching the temperature change can be obtained, and then the temperature value can be deduced.

[0102] When the detection object is deformed by external impact, the other two opposite ends of the four-resistance bridge will output a voltage signal proportional to the strain, and the temperature detection unit 5 outputs an instant temperature signal through a pair of wiring pads on it; the voltage signal is measured together with the vibration and temperature signals, and the three-parameter compensation calculation is performed to obtain the deformation value, and the deformation detection linear relationship includes temperature compensation calculation; before using the detection, in an experimental environment, use the accurately measured detection object sample to calibrate each sensitive unit to obtain the detection linear relationship. An example of the three-parameter compensation process is as follows:

[0103] S1. First, the function formulas of the voltage output of the strain full bridge and the vibration full bridge with respect to temperature change are established through the sensor calibration process.

[0104] S2. Use the signal acquisition and processing circuit to obtain the initial strain, vibration, and temperature signals, and use the above functional relationship to achieve temperature compensation of the strain and vibration time domain signals to obtain the strain time domain signal to be further processed and the real vibration time domain signal.

[0105] S3. Based on the advantages of the Fourier transform domain method, which has fast operation speed and accurate prediction of steady-state signals, spectrum analysis is performed by performing fast Fourier transform (FFT) on the historical sampling data of both.

[0106] S4. Feedback the frequency band with large amplitude and high energy in the above vibration spectrum to the strain processing end, and obtain the frequency domain information of the real strain signal by wavelet transform, adaptive filtering, bandpass filtering and the like.

[0107] S5. Use Inverse Fast Fourier Transform (IFFT) to restore the strain frequency domain signal to a time domain signal to achieve high-precision strain detection.

[0108] like Figure 7 The deformation detection unit shown is connected to the external detection circuit as shown in FIG. Figure 8 The temperature detection unit shown is connected to an external detection circuit and Fig. 9 The vibration detection unit shown can be shared after being connected to the amplifier A in the external detection circuit.

Claims

1. A deformation detection integrated micro-nano sensor, comprising a substrate, characterized in that: The substrate is an SOI silicon wafer, and the substrate comprises a bottom silicon layer (1), a buried oxide layer (2), and a top silicon layer (3) which are stacked and bonded in sequence from bottom to top. A detection unit is arranged on the top silicon layer (3), and the detection unit comprises a deformation detection unit (4). In order to eliminate the interference caused by the working environment vibration and temperature change to the high-precision measurement, corresponding compensation is provided for the deformation detection parameters. The detection unit also comprises a temperature detection unit (5) and a vibration detection unit (6). The final detection value of the deformation is based on the deformation parameter detected by the deformation detection unit (4), and the deformation parameter detected by the deformation detection unit (4) is compensated by the temperature parameter detected by the temperature detection unit (5) and the vibration parameter detected by the vibration detection unit (6).

2. The deformation detection integrated micro-nano sensor according to claim 1, characterized in that: The deformation detection unit (4) is a first silicon piezoresistive strip (7) in a zigzag reciprocating state formed by a silicon wafer doped with boron ions, and is composed of four groups of identical first silicon piezoresistive strips (7) connected in sequence to form a first four-resistance bridge; the four groups of first silicon piezoresistive strips (7) respectively lead out conductive leads to connect to first wiring pads (8) for respectively connecting to an external power supply and an external detection circuit.

3. The deformation detection integrated micro-nano sensor according to claim 1, characterized in that: The vibration detection unit (6) is a second silicon piezoresistive strip (9) in a zigzag reciprocating state formed by doping a silicon wafer with boron ions, and is formed by connecting four groups of identical second silicon piezoresistive strips (9) in sequence to form a second four-resistance bridge; the four groups of silicon piezoresistive strips respectively lead out leads to connect to the second wiring pads (10) for respectively connecting to an external power supply and an external detection circuit; and the top silicon (3) and the buried oxide layer (2) are formed by a wet etching process to form the following structure: comprising a cross beam (11) and a mass block (12), wherein the silicon piezoresistive strips are arranged on the cross beams (11) and the mass block (12) At the end of the beam (11), when external vibration is input, the vibration of the cross beam (11) and the mass block (12) causes the cross beam (11) to deform, thereby changing the resistance value of the second silicon piezoresistive strip (9); four groups of second silicon piezoresistive strips (9) respectively lead out conductive leads to connect to the second wiring pads (10), which are used to respectively connect to an external power supply and an external detection circuit; the bottom silicon (1) is subjected to a wet etching process at a position below the cross beam (11) and the mass block (12) to form a suspended cavity (17), so that the cross beam (11) and the mass block (12) are suspended below.

4. The deformation detection integrated micro-nano sensor according to claim 1, characterized in that: The temperature detection unit (5) comprises a temperature platinum resistor (13) arranged in a serpentine shape, a conductive lead and a third wiring pad (14), which is prepared on the top silicon layer (3) and isolated from the bottom top silicon layer (3) by an insulating material silicon nitride; the third wiring pad (14) is used to connect an external power supply and a detection circuit; the temperature platinum resistor (13) is formed by depositing a layer of metal platinum on the insulating layer entity using a lift-off process.

5. The deformation detection micro-nano sensor according to claim 3 or 4, characterized in that: The first silicon piezoresistive strip (7) and the second silicon piezoresistive strip (9) both include a heavily doped region (15) and a lightly doped region (16); the return section of the silicon piezoresistive strip is the heavily doped region (15), and the long straight strip connected between the return sections is the lightly doped region (16), so that the resistance distribution of the silicon piezoresistive strip is uniform; before the silicon wafer is doped with boron ions, a doped region reserved as the silicon piezoresistive strip and a non-doped region not serving as a functional region of the silicon piezoresistive strip are first demarcated, and the non-doped region is an etching object.

6. The deformation detection micro-nano sensor according to claim 5, characterized in that: The temperature detection unit (5) is formed by depositing a relatively thin layer of metal chromium and a relatively thick layer of metal platinum on the insulating layer entity using a lift-off process; the first wiring pad (8), the second wiring pad (10), and the third wiring pad (14) are all gold pads made of metal gold using a magnetron sputtering process.

7. The deformation detection integrated micro-nano sensor according to claim 1, characterized in that: The deformation detection integrated micro-nano sensor uses at least half of its substrate area as a vibration detection unit (6) area, and the remaining half area is used as a deformation detection unit (4) and a temperature detection unit (5).

8. The method for manufacturing a deformation detection micro-nano sensor according to claim 1, characterized in that: The method comprises the production of the deformation detection unit (4), the formation of an insulating layer, the production of a temperature detection unit (5) and the production of each wiring pad, demarcating a silicon piezoresistive strip reserved area on the top silicon (3), and performing ion implantation in the reserved area to form a lightly doped area (16) and a heavily doped area (15); and comprises the following steps: Step 1: A first silicon piezoresistive strip (7) and a second silicon piezoresistive strip (9) are fabricated on a 600A thermally oxidized SOI silicon wafer using a boron ion implantation process, wherein an implantation tilt angle is selected between 7° and 9°, and a sheet resistance value is between 72 and 90Ω; the thickness of each layer of the SOI silicon wafer is 10 μm for the top silicon (3), 1 μm for the buried oxide layer (2), and 400 μm for the bottom silicon (1). Step 2: LPCVD deposits 1500A-3000A low stress silicon nitride as an insulating layer between the subsequently prepared metal and the top silicon (3), and acts as a surface mask protection during subsequent wet etching; Step 3, using a Cr / Pt / Au metal film prepared by a magnetron sputtering process and patterning the metal using an ion beam etching (IBE) process to form a temperature detection unit (5) and a third wiring pad (14); Step 4: using plasma chemical vapor deposition (PECVD) to deposit 1500A-3000A of silicon nitride (Si3N4) as an insulating layer for the temperature detection unit (5) and the interconnection leads; Step 5: Reactive ion etching (RIE) is used to remove the silicon nitride (Si3N4) insulating layer on the surface of each wiring pad to expose each wiring pad; Step 6: Using reactive ion etching (RIE) to etch 3000A-6000A of surface silicon nitride (Si3N4); using deep etching (DRIE) to etch 10μm of top silicon (3); using reactive ion etching (RIE) to etch 1μm of buried oxide layer (2) to achieve accurate patterning of the cross beam (11)-mass block (12); Step 7: Prepare a 2000A thick silicon nitride (Si3N4) wet etching sidewall mask by plasma chemical vapor deposition (PECVD); Step 8, etching silicon nitride (Si3N4) with a thickness of 2000 Å by a maskless reactive ion etching process (RIE), leaving a composite mask layer on the side wall, opening an anisotropic etching window, and accurately forming a beam-mass block (12) structure by a wet etching process; Step 9: Finally, the silicon wafer is thinned to 200 μm-300 μm using chemical mechanical polishing (CMP).

9. The method for manufacturing a deformation detection micro-nano sensor according to claim 8, characterized in that: Said In step 1, the thickness of thermal oxidation is preferably 600 Å, the ion implantation energy is preferably 40 keV, the incident angle is 7°, and the heavily doped sheet resistance is about 2 Ω and the lightly doped sheet resistance is about 80 Ω; In step 2, preferably LPCVD (low pressure chemical vapor deposition) is used to deposit 3000A low stress silicon nitride; In step 3, the thickness of the Cr / Pt / Au metal film is preferably 500A / 3000A / 500A, the metal line width of the temperature sensitive unit is preferably 15 μm, and the size of the third wiring pad (14) is 1 mm*1 mm; In step 4, 3000A of silicon nitride is preferably deposited using a plasma chemical vapor deposition process (PECVD); In step 5, the depth of etching silicon nitride is preferably 3000 Å, which is consistent with the deposition thickness in step S4; In step 6, the thickness of the surface silicon nitride is preferably etched to 6000 Å; In step 9, the thickness of the silicon wafer thinned is preferably 250 μm.

10. A deformation detection method, characterized in that: The deformation detection integrated micro-nano sensor as claimed in any one of claims 1 to 7 is used. When used for detection, the deformation detection integrated micro-nano sensor is connected to an external circuit and the deformation detection micro-nano sensor is firmly fixed on the detection object; when used, a pair of wiring pads 3 in the deformation detection unit (4) is connected to an external power supply to provide an excitation voltage for one pair of opposite ends of the four-resistance bridge, and another pair of wiring pads 3 in the deformation detection unit (4) is connected to an external voltage detection circuit; similarly, when used, a pair of wiring pads in the vibration detection unit (6) is connected to an external power supply to provide an excitation voltage for one pair of opposite ends of the four-resistance bridge, and another pair of wiring pads is connected to an external voltage detection circuit. The temperature detection unit (5) is connected to an external temperature detection circuit via a pair of wiring pads 2 on the temperature detection unit (5); when the detection object is deformed by external force impact, the other pair of opposite ends of the four-resistance bridge of the deformation detection unit (4) will output a voltage signal proportional to the deformation amount, the temperature detection unit (5) outputs an instant temperature signal via a pair of wiring pads 5 on the temperature detection unit (5), and the other pair of opposite ends of the four-resistance bridge of the vibration detection unit (6) outputs a voltage signal reflecting the current vibration condition of the object under test; the relevant electrical signals of the three physical parameters measured are mathematically converted to eliminate the interference of temperature and vibration on deformation detection, and calculate the accurate deformation value; Before use, in an experimental environment, the deformation detection micro-nano sensor is calibrated using a sample of the detection object that has been accurately measured to obtain the deformation detection linear relationship; the deformation represents the relative change in length, which is the ratio of the deformation variable to the original length dimension, represented by the mathematical symbol ε, that is, ε=ΔL / L, dimensionless, and expressed as a percentage.

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