A MEMS six-in-one monolithic integrated sensor and a manufacturing method thereof

Abstract

The application provides a manufacturing method of a six-in-one monolithic integrated sensor based on MEMS technology, which comprises the following steps: depositing an isolation layer on a silicon wafer, manufacturing a sacrifice layer by using polysilicon, depositing low-stress silicon nitride as a structure layer and a sensitive diaphragm, manufacturing a sensitive device on the sensitive diaphragm, etching the sacrifice layer by using XeF2 gas which can pass through the etching release holes on the sensitive diaphragm, and plugging all the etching release holes after the etching is stopped. The six-in-one monolithic integrated sensor integrates the functions of pressure, acceleration, gas, humidity, temperature and microphone sensors on a single silicon wafer, and can be applied to complex scenes such as emergency rescue and public safety, so as to improve the work efficiency. The yield of the integrated sensor reaches a high level by using the above-mentioned sacrifice layer and etching material, the manufacturing cost is greatly reduced, and the integrated sensor is compatible with IC.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor devices, in particular to a MEMS monolithic integrated composite sensor with multiple functions. BACKGROUND

[0002] MEMS (Micro Electro Mechanical Systems) is a micro integrated system that uses integrated circuit manufacturing technology and micro processing technology to manufacture micro structures, micro sensors, micro actuators, control processing circuits, and even interfaces, communication and power supply on one or more chips. The sensors made by MEMS technology have been widely used in various fields, such as smart home appliances, emergency rescue, public safety, robots, etc.

[0003] Taking a rescue robot as an example, it needs all-around sensing ability to improve the search and rescue efficiency, so it must have functions such as vision, touch, smell, hearing, etc., so it needs to install image sensors, pressure sensors, gas sensors, microphone sensors and other sensor units. If a large number of sensors of various types exist in a single form and are assembled on the application body, the total occupied area, total power consumption will be relatively large, and the total cost will also be relatively high. Therefore, the integration of multiple function sensors has become an important trend in the development of sensors.

[0004] Traditional sensor integration mainly focuses on 2 or 3, with less function, and mostly made by bulk silicon micro processing technology, with low yield and high manufacturing cost, and cannot be compatible with IC.

[0005] Therefore, a new integrated sensor is needed to integrate more types of sensors and improve yield and reduce manufacturing cost. SUMMARY

[0006] The purpose of the present application is to provide a MEMS six-in-one monolithic integrated sensor and a manufacturing method thereof, to integrate the functions of pressure, acceleration, gas, humidity, temperature and microphone sensors, and to improve the work efficiency and yield.

[0007] In order to achieve the above purpose, the present application provides a manufacturing method of a MEMS six-in-one monolithic integrated sensor, for the integration of acceleration sensors, pressure sensors, gas sensors, humidity sensors, temperature sensors and microphone sensors, comprising:

[0008] S1: providing a silicon wafer, depositing an isolation layer on the silicon wafer;

[0009] S2: using polysilicon to respectively manufacture the bosses of the acceleration, pressure, gas, humidity sensors and the etching pins adjacent to each boss on the isolation layer as a sacrificial layer, thereby obtaining a silicon wafer with a sacrificial layer;

[0010] S3: depositing a low-stress silicon nitride layer on the silicon wafer with the sacrificial layer as a structural layer and a sensitive diaphragm;

[0011] S4: fabricating a sensitive device based on the deformation of the sensitive diaphragm on the sensitive diaphragm, the sensitive device including sensitive resistors required by acceleration, pressure and temperature sensors;

[0012] S5: etching until the silicon wafer is exposed at the position corresponding to the microphone sensor to form a groove of the microphone sensor;

[0013] S6: sequentially fabricating, from bottom to top, a lower electrode of the microphone sensor, a support layer of the microphone sensor and a vibrating diaphragm of the microphone sensor at the groove of the microphone sensor;

[0014] S7: fabricating electrode leads of the acceleration, pressure and temperature sensors respectively on the sensitive resistors of the acceleration, pressure and temperature sensors, sequentially fabricating a heating electrode, an insulating layer and a test electrode of the gas sensor on the sensitive diaphragm at the gas sensor, fabricating a test electrode of the humidity sensor on the sensitive diaphragm at the humidity sensor, and fabricating a mass at the sensitive diaphragm at the acceleration sensor;

[0015] S8: etching the sensitive diaphragm above the etching pin to obtain an etching release hole penetrating through the sensitive diaphragm;

[0016] S9: placing the silicon wafer in a XeF2 gas atmosphere, so that the XeF2 gas etches the sacrificial layer through the etching release hole, and stopping etching when the color of the boss is observed to change completely;

[0017] S10: depositing a multilayer material formed by alternation of silicon nitride and silicon dioxide at the etching release hole to obtain a plugging layer to plug all the etching release holes;

[0018] S11: etching the support layer of the microphone sensor to form an air gap of the microphone sensor;

[0019] S12: releasing a cantilever beam of the acceleration sensor by etching the sensitive diaphragm at the acceleration sensor;

[0020] S13: coating sensitive materials of the gas sensor and the humidity sensor on the test electrodes of the gas sensor and the humidity sensor respectively to obtain a MEMS six-in-one monolithic integrated sensor.

[0021] The step S2 specifically includes:

[0022] S21: depositing polysilicon on the isolation layer, and performing photoetching and etching to pattern the polysilicon and form a boss for each of the acceleration sensor, pressure sensor, gas sensor and humidity sensor;

[0023] S22: depositing polysilicon again on the isolation layer, and performing photoetching and etching to pattern the polysilicon and form a corrosion pin adjacent to each boss.

[0024] The sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor are polysilicon resistors, and the step S4 specifically comprises:

[0025] S41: depositing low-stress polysilicon on the sensitive diaphragm, performing boron ion implantation annealing, and then performing photoetching and etching to pattern the polysilicon and form the sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor at positions corresponding to the sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor, respectively;

[0026] S42: depositing low-stress silicon nitride as a protective layer for the sensitive resistors on the sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor.

[0027] The step S6 specifically comprises:

[0028] S61: performing phosphorus ion implantation and annealing on the silicon wafer at the recess of the microphone sensor to form a lower electrode of the microphone sensor;

[0029] S62: sputtering aluminum as a sacrifice layer and support layer of the microphone sensor on the recess of the microphone sensor;

[0030] S63: fabricating a vibrating diaphragm 603 of the microphone sensor on the support layer 602 of the microphone sensor, the vibrating diaphragm 603 also serving as an upper electrode of the microphone sensor, the vibrating diaphragm 603 being obtained by sputtering a layer of gold and patterning the layer of gold to have a plurality of air holes.

[0031] The number of the air holes is within 64, and the size of each air hole is within 20 μm x 20 μm; the thickness of the vibrating diaphragm 603 of the microphone sensor is

[0032] The step S7 specifically comprises:

[0033] S71: etching the protective layer of the sensitive resistor of the acceleration sensor, pressure sensor and temperature sensor, respectively, to form a lead hole of the sensitive resistor, sputtering a layer of gold as an electrode lead of the sensitive resistor at the lead hole, and sputtering a layer of gold as a heating electrode of the gas sensor at the gas sensor;

[0034] S72: depositing a layer of silicon dioxide on the heating electrode of the gas sensor as an insulating layer of the gas sensor;

[0035] S73: sputtering a layer of gold on the heating electrode of the gas sensor as a test electrode of the gas sensor, and sputtering a layer of gold on the sensitive diaphragm of the gas sensor as a test electrode of the humidity sensor;

[0036] S74: depositing a mass block on the sensitive diaphragm of the acceleration sensor by electroplating.

[0037] The depth of the electrode lead of the sensitive resistor is The etching depth of the lead hole is The thickness of the insulating layer of the gas sensor is The thickness of the test electrode of the gas sensor and the test electrode of the humidity sensor is The mass block is made of copper, and the thickness of the mass block is within 10 μm.

[0038] In the step S1, the silicon wafer is a single-polished N+ type <100> silicon wafer; the isolation layer is low-stress silicon nitride, and the thickness thereof is In the step S3, the thickness of the sensitive diaphragm is In the step S4, the thickness of the sensitive resistor is

[0039] The sensitive material of the gas sensor is SnO2 or TiO2, the sensitive material of the humidity sensor is ZnO or PEG, and the sensitive material of the gas and humidity sensors is prepared by spotting and coating on the test electrode of the gas and humidity sensors.

[0040] In another aspect, the application provides a MEMS six-in-one monolithic integrated sensor, which is prepared based on the preparation method of the MEMS six-in-one monolithic integrated sensor.

[0041] The preparation method of the MEMS six-in-one monolithic integrated sensor can prepare an integrated sensor integrated with the functions of six sensors of pressure, acceleration, gas, humidity, temperature and microphone, each sensor component can work normally and has a certain level of performance, so that six kinds of physical quantities can be detected at the same time, and then applied to the synchronous detection of multiple physical quantities in complex scenes, such as emergency rescue, public safety and environmental detection, which need to obtain multiple physical quantities at the same time, so as to improve the work efficiency; the six-in-one monolithic integrated sensor is prepared by surface silicon micro-machining technology, has high yield, low manufacturing cost, and is compatible with IC. Therefore, it can be applied to complex scenes and detect six kinds of physical quantities at the same time.

[0042] In addition, the manufacturing method of the MEMS six-in-one monolithic integrated sensor of the present application adopts polycrystalline silicon filling as a sacrificial layer before forming a cavity, and adopts XeF2 gas atmosphere to corrode the sacrificial layer, without damaging other parts of the structure when corroding the substance, and the corrosion speed is not too slow, and the speed is faster and easier to control; compared with the traditional method of adopting silicon dioxide as a sacrificial layer and adopting HF to corrode, the device structure can be avoided to be damaged, and the yield is improved. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a flow chart of the manufacturing method of the MEMS six-in-one monolithic integrated sensor of the present application;

[0044] Figures 2A-2R is a cross-sectional schematic diagram of a silicon wafer and its upper components at each step of the manufacturing method of the MEMS six-in-one monolithic integrated sensor of the present application.

[0045] Figure 3 is a schematic diagram of the sensor size and position of the MEMS six-in-one monolithic integrated sensor of the present application.

[0046] Figure 4A is a photo of the MEMS six-in-one monolithic integrated sensor of the present application, wherein the left half of the figure is a microscope photo of the MEMS four-in-one monolithic integrated sensor of the present application, and the right half of the figure is a comparison photo with a 1-yuan coin.

[0047] Figure 4B is a response result diagram of the pressure sensor of the MEMS six-in-one monolithic integrated sensor of the present application.

[0048] Figure 4C is a response result diagram of the acceleration sensor of the MEMS six-in-one monolithic integrated sensor of the present application.

[0049] Figure 4D is a response result diagram of the gas sensor of the MEMS six-in-one monolithic integrated sensor of the present application.

[0050] Figure 4E is a response result diagram of the humidity sensor of the MEMS six-in-one monolithic integrated sensor of the present application.

[0051] Figure 4F is a response result diagram of the temperature sensor of the MEMS six-in-one monolithic integrated sensor of the present application.

[0052] Figure 4G is a response result diagram of the microphone sensor of the MEMS six-in-one monolithic integrated sensor of the present application. DETAILED DESCRIPTION

[0053] The application will be further described in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate but not to limit the scope of the application.

[0054] As shown in Figure 1 is a flow chart of a manufacturing method of a MEMS six-in-one monolithic integrated sensor according to an embodiment of the application, which can be applied to synchronous detection of multiple physical quantities in complex scenes, such as emergency rescue, public safety and environmental detection scenes, which need to obtain multiple physical quantities at the same time, thereby improving the operation efficiency.

[0055] The manufacturing method of the MEMS six-in-one monolithic integrated sensor of the application is used for integration of an acceleration sensor 10, a pressure sensor 20, a gas sensor 30, a humidity sensor 40, a temperature sensor 50 and a microphone sensor 60, which comprises the following steps:

[0056] Step S1: as shown in Figure 2A , a silicon wafer 100 is provided, and a layer of isolation layer 200 is deposited on the silicon wafer 100.

[0057] In the embodiment, the deposition adopts an LPCVD process. The silicon wafer 100 is a single-polished N+ type <100> silicon wafer, and the isolation layer 200 is low-stress silicon nitride, which has a thickness of In other embodiments, the material of the isolation layer can be selected and the thickness can be adjusted in the range of .

[0058] Step S2: polycrystalline silicon is used to manufacture the respective bosses of the acceleration, pressure, gas and humidity sensors and the respective etching pins adjacent to the bosses on the isolation layer 200 as a sacrificial layer, thereby obtaining a silicon wafer with a sacrificial layer;

[0059] That is, the bosses include a first boss 301 corresponding to the acceleration sensor, a second boss 302 corresponding to the pressure sensor, a third boss 303 corresponding to the gas sensor, and a fourth boss 304 corresponding to the humidity sensor. The first boss 301, the second boss 302, the third boss 303 and the fourth boss 304 are respectively adjacent to the first etching pin 305, the second etching pin 306, the third etching pin 307 and the fourth etching pin 308.

[0060] Among them, the sacrificial layer is used as a filler for forming the bosses and the etching pins so as to be released subsequently; the bosses are used to become vacuum cavities after being released, so that the sensitive diaphragm can be deformed when external load is applied to the sensitive diaphragm; the etching pins are used as a "fuse" when the bosses are released, which is used to guide the etching gas and accelerate the etching speed.

[0061] The step S2 specifically comprises:

[0062] Step S21: As Figure 2B As shown, polysilicon is deposited on the isolation layer, and photolithography and etching are performed on it (i.e. the deposited polysilicon) to pattern it and form respective bosses of the acceleration, pressure, gas, and humidity sensors at the positions corresponding to the acceleration, pressure, gas, and humidity sensors.

[0063] In this embodiment, the deposition is performed using an LPCVD process. In this embodiment, the boss has a thickness of... In other embodiments, its thickness is It is adjustable within a certain range.

[0064] Step S22: As Figure 2C As shown, a layer of polysilicon is deposited again on the isolation layer and then photolithographically and etched to pattern it and form etched pins adjacent to the respective bosses.

[0065] In this embodiment, the deposition is performed using an LPCVD process. The thickness of the etched pin is... Furthermore, in other embodiments, its thickness is... It is adjustable within a certain range.

[0066] Step S3: As Figure 2D As shown, a low-stress silicon nitride layer is deposited on the entire silicon wafer with a sacrificial layer as a structural layer and a sensitive film 400.

[0067] Low-stress silicon nitride serves as both a structural layer for devices and a sensitive film.

[0068] In this embodiment, the deposition is performed using an LPCVD process. The thickness of the sensitive film 400 is... Furthermore, in other embodiments, its thickness is... It is adjustable within a certain range.

[0069] Step S4: As Figure 2E As shown, a sensitive device that changes based on the deformation of the sensitive diaphragm is fabricated on the sensitive diaphragm 400. The sensitive device includes a sensitive resistor required for acceleration, pressure and temperature sensors.

[0070] In this embodiment, as Figure 2E As shown, the sensitive resistors of the acceleration, pressure, and temperature sensors are polycrystalline silicon resistors, and step S4 specifically includes:

[0071] Step S41: Deposit a layer of low-stress polysilicon on the sensitive diaphragm 400, perform boron ion implantation annealing on it, and then perform photolithography and etching on the polysilicon to pattern it and form the sensitive resistors of the acceleration, pressure and temperature sensors at the positions corresponding to the sensitive resistors of the acceleration, pressure and temperature sensors respectively.

[0072] Therefore, the piezoresistive resistor 501, used as the accelerometer, and the piezoresistive resistor 502, used as the pressure sensor, form a Wheatstone bridge, outputting the change in quantity in electrical form. The thermistor 503, used as the temperature sensor, has a resistance that changes with temperature.

[0073] The deposition was performed using an LPCVD process. The thickness of the sensitive resistor is... In other embodiments, its thickness is adjustable. The sensitive resistor obtained after photolithography is in the shape of a serpentine resistor strip. The ion implantation energy for implantation annealing is 60 keV, and the implantation dose is 5 × 10⁻⁶. 15 ions / cm 2 The annealing temperature is 1000 degrees Celsius, and nitrogen gas is introduced.

[0074] Step S42: Deposit a layer of low-stress silicon nitride at the sensitive resistors of the acceleration, pressure, and temperature sensors as a protective layer for the sensitive resistors.

[0075] The deposition process employs LPCVD. In this embodiment, the thickness of the protective layer for the varistor is [missing information]. In other embodiments, its thickness is adjustable.

[0076] Step S5: As Figure 2F As shown, the sensitive film 400 and the isolation layer 200 are etched at the location corresponding to the microphone sensor until the silicon wafer 100 is exposed, forming a groove for the microphone sensor;

[0077] Step S6: The lower electrode 601 of the microphone sensor, the support layer 602 of the microphone sensor, and the diaphragm 603 of the microphone sensor are fabricated sequentially from bottom to top in the groove of the microphone sensor.

[0078] Step S6 specifically includes:

[0079] Step S61: As Figure 2G As shown, phosphorus ions (P+) are implanted and annealed on the silicon wafer 100 at the groove of the microphone sensor to form the lower electrode 601 of the microphone sensor.

[0080] Step S62: As Figure 2H As shown, an aluminum layer is sputtered at the groove of the microphone sensor as a sacrificial layer and support layer 602 for the microphone sensor.

[0081] The microphone sensor support layer 602 covers a portion of the lower electrode 601 of the microphone sensor. The thickness of the microphone sensor support layer 602 is... In other embodiments, its thickness is adjustable.

[0082] Step S63: AsFigure 2I As shown, a diaphragm 603 of the microphone sensor is fabricated on the support layer 602 of the microphone sensor, and the diaphragm of the microphone sensor also serves as the upper electrode of the microphone sensor.

[0083] The microphone sensor's diaphragm 603 is obtained by sputtering a layer of gold and patterning it to have multiple pores. In this embodiment, the thickness of the microphone sensor's diaphragm 603 is [missing information]. The number of pores is 36, and the size of each pore is 10μm×10μm. In other embodiments, the number of pores is less than 64, the size is less than 20μm×20μm, and the thickness of the microphone sensor diaphragm 603 is adjustable.

[0084] Step S63 may further include: fabricating an electrode lead 604 of the microphone sensor on the lower electrode 601 of the microphone sensor.

[0085] The electrode leads 604 of the microphone sensor are obtained by sputtering a layer of gold.

[0086] Step S7: Fabricate electrode leads 701 for the acceleration, pressure, and temperature sensors respectively on the sensitive resistors of the acceleration sensor, pressure sensor, and temperature sensor. Sequentially fabricate the heating electrode 702, insulating layer 703, and test electrode 704 of the gas sensor on the sensitive diaphragm 400 at the gas sensor. Fabricate the test electrode 705 of the humidity sensor on the sensitive diaphragm 400 at the humidity sensor. Fabricate a mass block 706 on the sensitive diaphragm 400 at the acceleration sensor.

[0087] In this design, the electrode leads 701 of the pressure sensor and accelerometer serve as the leads for the Wheatstone circuit of the accelerometer. Therefore, the fabrication of the Wheatstone bridge involves first forming a serpentine varistor; then sputtering a layer... Au is used as a lead in the Wheatstone circuit, and the varistor is also connected into the Wheatstone circuit.

[0088] Therefore, the lower heating electrode of the gas sensor is used to heat the gas-sensitive material to facilitate its reaction with the gas; the upper test electrode is used to output the resistance change as an electrical quantity.

[0089] Step S7 specifically includes:

[0090] Step S71: As Figure 2J As shown, the protective layers of the sensitive resistors of the acceleration, pressure and temperature sensors are etched to form lead holes of the sensitive resistors, and a layer of gold is sputtered at the lead holes as electrode leads 701 of the sensitive resistors. A layer of gold is sputtered at the gas sensor to form the heating electrode 702 of the gas sensor.

[0091] The depth of the electrode leads of the sensitive resistor is... The etching depth of the lead hole is

[0092] Step S72: As Figure 2K As shown, a layer of silicon dioxide is deposited on the heating electrode of the gas sensor as the insulating layer 703 of the gas sensor.

[0093] The deposition process employed is PECVD, and the thickness of the insulating layer 703 in the gas sensor is [missing information]. In other embodiments, its thickness is adjustable.

[0094] Step S73: As Figure 2L As shown, a layer of gold is sputtered on the heating electrode of the gas sensor to serve as the test electrode 704 of the gas sensor, and a layer of gold is sputtered on the sensitive diaphragm 400 at the gas sensor to serve as the test electrode 705 of the humidity sensor.

[0095] In this embodiment, the thickness of the test electrode of the gas sensor and the test electrode of the humidity sensor is [missing information]. In other embodiments, its thickness is adjustable.

[0096] Step S74: As Figure 2M As shown, a mass block 706 is deposited on the sensitive diaphragm 400 at the accelerometer using an electroplating method to increase sensitivity.

[0097] In this embodiment, the mass block 706 is made of copper, and as verified by the accompanying sample, the thickness of the mass block 706 is 6 μm. In other embodiments, the thickness of the mass block 706 can be within 10 μm.

[0098] Step S8: As Figure 2N As shown, the sensitive diaphragm 400 above the corrosion pin is etched to obtain a corrosion release hole 401 that penetrates the sensitive diaphragm 400;

[0099] Thus, corrosion release holes for acceleration, pressure, gas, and humidity sensors were obtained.

[0100] Step S9: As Figure 2O As shown, the silicon wafer is placed in an XeF2 gas atmosphere, allowing the XeF2 gas to etch the sacrificial layer through the etching release holes (Note: the area except for the etching release holes is covered with photoresist such as PECVD SiN). At the same time, the color of the protrusions under the sensitive film 400 is observed to change multiple times. The etching is stopped when the color of all the protrusions has changed.

[0101] At this point, the cavity structure is formed. After etching stops, the silicon wafer can be cleaned and dried.

[0102] The boss under the sensitive diaphragm 400 is originally grayish brown, and the color changes to orange after the color change. When the color changes completely, all the polysilicon is completely etched clean.

[0103] Step S10: as shown in the figure, depositing a silicon nitride-silicon dioxide-silicon nitride multilayer material at the etching release hole to obtain a blocking layer 402 to block all etching release holes. Figure 2P The multilayer material superposition can improve the density, thereby improving the air tightness of the cavity. In addition, the multilayer material can also be silicon dioxide-silicon nitride-silicon dioxide, as long as the multilayer material formed by alternating silicon nitride and silicon dioxide.

[0104] To obtain the blocking layer, specifically comprising: depositing silicon nitride, silicon dioxide, and silicon nitride by PECVD to obtain a silicon nitride-silicon dioxide-silicon nitride multilayer material, and performing photolithography and etching to pattern the multilayer material, thereby obtaining the blocking layer.

[0105] The thickness of the silicon nitride, silicon dioxide, and silicon nitride of the silicon nitride-silicon dioxide-silicon nitride multilayer material is respectively

[0106] In other embodiments, the thickness can be adjusted as long as the blocking layer can completely block the release hole, that is, the deposition thickness of the blocking layer is higher than the depth of the etching release hole.

[0107] Step S11: as shown in the figure, placing the silicon wafer in an aluminum etching solution to etch the support layer 602 of the microphone sensor to form an air gap of the microphone sensor. Figure 2Q Specifically, it is verified by the wafer that when etching the support layer 602 of the microphone sensor, the silicon wafer needs to be placed in the aluminum etching solution for 30-40 minutes, and then the etching is stopped to form the air gap of the microphone sensor.

[0108] After step S11, it can also include cleaning the silicon wafer and drying.

[0109] Step S12: as shown in the figure, etching the sensitive diaphragm 400 at the acceleration sensor to release a cantilever beam 403 of the acceleration sensor.

[0110] Figure 2R In this embodiment, the etching position of the sensitive diaphragm 400 at the acceleration sensor is the position adjacent to the mass 706.

[0111] In this embodiment, the etching position of the sensitive diaphragm 400 at the acceleration sensor is the position adjacent to the mass 706.

[0112] ​​Step S13: Coat the gas-sensitive material of the gas sensor and the humidity-sensitive material of the humidity sensor onto the test electrode 704 of the gas sensor and the test electrode 705 of the humidity sensor, respectively, to obtain a MEMS six-in-one monolithic integrated sensor. The obtained MEMS six-in-one monolithic integrated sensor integrates an accelerometer 10, a pressure sensor 20, a gas sensor 30, a humidity sensor 40, a temperature sensor 50, and a microphone sensor 60.

[0113] The gas-sensitive material for the gas sensor is SnO2 / TiO2, and the humidity-sensitive material for the humidity sensor is ZnO / PEG. The sensitive materials for the gas and humidity sensors (i.e., the gas-sensitive material for the gas sensor and the humidity-sensitive material for the humidity sensor) are fabricated by spot-coating the test electrodes of the gas and humidity sensors.

[0114] At this point, the entire process of manufacturing the six-in-one monolithic integrated sensor is complete. Therefore, the six-in-one monolithic integrated sensor fabricated using the method described above integrates six sensors: pressure, acceleration, gas, humidity, temperature, and microphone. The position and dimensions of the six sensors are as follows... Figure 3 As shown, this six-in-one monolithic integrated sensor is fabricated using surface-mount silicon micromachining technology. In this embodiment, the entire six-in-one monolithic integrated sensor occupies an area of ​​only 2.5mm × 2.5mm (specifically, the dimensions of the accelerometer 10 are 900μm × 1910μm, the pressure sensor 20 is 550μm × 430μm, the gas sensor 30 is 1100μm × 560μm, the humidity sensor 40 is 570μm × 570μm, the temperature sensor 50 is 250μm × 410μm, and the microphone sensor 60 is 1090μm × 530μm). The six-in-one monolithic integrated sensor has a high yield rate, low manufacturing cost, and is compatible with ICs. Each sensor component functions normally and achieves a certain level of performance, thus it can be applied to complex scenarios and simultaneously detect six types of physical quantities.

[0115] The microscope image of the completed six-in-one sensor is shown in 4A(a), and its comparison with a one-yuan coin is shown in 4A(b). The sensitivity of its pressure sensor was experimentally measured to be 0.2 mV / kPa. Figure 4B As shown; the sensitivity of the accelerometer is 129.5 μV / g, as... Figure 4C As shown; the gas sensor's response time is 32 seconds, as... Figure 4D As shown; the humidity sensor's humidity-sensitive range is 0-95% RH, such as... Figure 4E As shown; the temperature sensor's sensitivity is 8.8Ω / ℃, as... Figure 4FThe microphone audio detectable range covers the human hearing range (20-2000Hz), as shown in the figure. Figure 4G It can be seen that each sensor can work normally and has good performance.

[0116] The application firstly adopts the MEMS surface micromachining technology to integrate the microphone sensor and other functional sensors on a single chip; each sensor is selected with a reasonable type, and the pressure sensor, acceleration sensor, gas sensor, humidity sensor, temperature sensor and microphone are successfully integrated on a single silicon chip through the optimization of the surface micromachining process and the optimization of the manufacturing step sequence.

[0117] The pressure sensor and the acceleration sensor adopt the absolute pressure-resistance type sensor, so a cavity needs to be formed; when the external load is loaded on the sensitive diaphragm of the pressure sensor and the acceleration sensor, the structural layer will be deformed, and then the polysilicon resistor will be deformed, so as to change the resistance value of the polysilicon resistor, and the change amount is output through the Wheatstone bridge. The gas and humidity need to form a cavity in order to reduce the power consumption.

[0118] The heating electrode of the gas sensor is used to make the temperature reach the temperature required for the gas-sensitive material to react, and the test electrode is used to output the change amount; the silicon dioxide is used as the isolation layer between the heating electrode and the test electrode; when the external measured quantity reacts with the sensitive material (such as the gas-sensitive material of the gas sensor and the humidity-sensitive material of the humidity sensor), the conductivity of the sensitive material will change, so as to change the total resistance value of the sensitive material and the test electrode, and the change amount is output through the test electrode.

[0119] The temperature sensor utilizes the temperature-sensitive effect of polysilicon, and the corresponding temperature value is measured through the resistance value change of the sensitive resistor.

[0120] The microphone adopts the capacitive type, and gold is used as the vibration diaphragm and the upper electrode for sensing sound pressure due to good flexibility, and the silicon sheet with ion injection on the surface is used as the lower electrode. When the sound pressure acts on the gold diaphragm, the gold diaphragm will be deformed, so as to change the capacitance value of the upper and lower electrodes, and thus the corresponding sound pressure value is measured.

[0121] The above is only a preferred embodiment of the application, and is not used to limit the scope of the application, and various changes can be made to the above-mentioned embodiments of the application. Any simple, equivalent changes and modifications made according to the content of the claims and the description of the application fall within the scope of protection of the patent. The application is not described in detail, and all are conventional technical contents.

Claims

1. A method for manufacturing a MEMS six-in-one monolithic integrated sensor for integration of an acceleration sensor, a pressure sensor, a gas sensor, a humidity sensor, a temperature sensor, and a microphone sensor, characterized by, The application relates to a method for manufacturing a MEMS six-in-one single-chip integrated sensor. The method comprises the following steps: Step S1: providing a silicon wafer, and depositing an isolation layer on the silicon wafer; Step S2: using polysilicon to respectively manufacture a boss of an acceleration sensor, a pressure sensor, a gas sensor and a humidity sensor and a corrosion lead adjacent to each boss on the isolation layer, taking the bosses as a sacrifice layer, so as to obtain a silicon wafer with a sacrifice layer; Step S3: depositing a low-stress silicon nitride layer on the silicon wafer with the sacrifice layer, taking the low-stress silicon nitride layer as a structure layer and a sensitive diaphragm; Step S4: manufacturing a sensitive device based on deformation of the sensitive diaphragm on the sensitive diaphragm, wherein the sensitive device comprises sensitive resistors required by the acceleration sensor, the pressure sensor and the temperature sensor; Step S5: etching until the silicon wafer is exposed at a position corresponding to a microphone sensor, so as to form a groove of the microphone sensor; Step S6: sequentially manufacturing a lower electrode of the microphone sensor, a support layer of the microphone sensor and a vibrating diaphragm of the microphone sensor from bottom to top at the groove of the microphone sensor; Step S7: respectively manufacturing electrode leads of the acceleration sensor, the pressure sensor and the temperature sensor on the sensitive resistors of the acceleration sensor, the pressure sensor and the temperature sensor, sequentially manufacturing a heating electrode, an insulating layer and a test electrode of the gas sensor on the sensitive diaphragm at the gas sensor, manufacturing a test electrode of the humidity sensor on the sensitive diaphragm at the humidity sensor, and manufacturing a mass block on the sensitive diaphragm at the acceleration sensor; Step S8: etching the sensitive diaphragm above the corrosion leads, so as to obtain corrosion release holes penetrating through the sensitive diaphragm; Step S9: placing the silicon wafer in a XeF2 gas atmosphere, so that the XeF2 gas corrodes the sacrifice layer through the corrosion release holes, and the corrosion is stopped when the color of the bosses is observed to change completely; Step S10: depositing a multilayer material formed by alternation of silicon nitride and silicon dioxide at the corrosion release holes, so as to obtain a plugging layer for plugging all the corrosion release holes; Step S11: etching the support layer of the microphone sensor, so as to form an air gap of the microphone sensor; Step S12: releasing a cantilever beam of the acceleration sensor by etching the sensitive diaphragm at the acceleration sensor; 2. The method of claim 1, wherein the MEMS six-in-one monolithically integrated sensor is a six-in-one monolithically integrated sensor including a pressure sensor, a temperature sensor, a humidity sensor, a flow sensor, a gas sensor, and a light sensor. Step S13: respectively coating a gas-sensitive material of the gas sensor and a humidity-sensitive material of the humidity sensor on the test electrodes of the gas sensor and the humidity sensor, so as to obtain the MEMS six-in-one single-chip integrated sensor. The step S2 specifically comprises the following steps: Step S21: depositing polysilicon on the isolation layer, and performing photoetching and etching on the polysilicon, so as to pattern the polysilicon and form bosses of the acceleration sensor, the pressure sensor, the gas sensor and the humidity sensor at positions corresponding to the acceleration sensor, the pressure sensor, the gas sensor and the humidity sensor; 3. The method of claim 1, wherein the MEMS six-in-one monolithically integrated sensor is a six-in-one monolithically integrated pressure sensor. Step S22: again depositing a polysilicon layer on the isolation layer, and performing photoetching and etching on the polysilicon layer, so as to pattern the polysilicon layer and form corrosion leads adjacent to the bosses. The sensitive resistors of the acceleration sensor, the pressure sensor and the temperature sensor are polysilicon resistors, and the step S4 specifically comprises the following steps: Step S41: depositing a low-stress polysilicon layer on the sensitive diaphragm, boron ion implantation annealing, then photoetching and etching the polysilicon to patternize it and form sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor respectively at positions corresponding to the sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor; Step S42: depositing a low-stress silicon nitride layer as a protective layer of the sensitive resistors at the sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor.

4. The method of claim 1, wherein the MEMS six-in-one monolithically integrated sensor is a six-in-one monolithically integrated pressure sensor. The step S6 specifically comprises: Step S61: phosphorus ion implantation and annealing on the silicon wafer at the groove of the microphone sensor to form a lower electrode of the microphone sensor; Step S62: sputtering an aluminum layer as a sacrificial layer and support layer of the microphone sensor at the groove of the microphone sensor; Step S63: fabricating a vibrating diaphragm of the microphone sensor on the support layer of the microphone sensor, the vibrating diaphragm of the microphone sensor also serving as an upper electrode of the microphone sensor, the vibrating diaphragm of the microphone sensor being obtained by sputtering a gold layer and patterning it to have a plurality of air holes.

5. The method of claim 4, wherein the MEMS six-in-one monolithically integrated sensor is a six-in-one monolithically integrated pressure sensor. The number of the air holes is less than 64, and the size is less than 20 μm x 20 μm; the thickness of the vibrating diaphragm of the microphone sensor is less than 1 μm 6. The method of claim 1, wherein The step S7 specifically comprises: Step S71: etching the protective layers of the sensitive resistors of the acceleration sensor, pressure sensor and temperature sensor respectively to form lead holes of the sensitive resistors, sputtering a gold layer as electrode leads of the sensitive resistors at the lead holes, and sputtering a gold layer at the gas sensor to form a heating electrode of the gas sensor; Step S72: depositing a silicon dioxide layer as an insulating layer of the gas sensor on the heating electrode of the gas sensor; Step S73: sputtering a gold layer as a test electrode of the gas sensor on the heating electrode of the gas sensor, and sputtering a gold layer as a test electrode of the humidity sensor on the sensitive diaphragm at the gas sensor; Step S74: depositing a mass at the sensitive diaphragm of the acceleration sensor by electroplating.

7. The method of claim 6, wherein the MEMS six-in-one monolithically integrated sensor is a six-in-one monolithically integrated pressure sensor. The thickness of the electrode lead of the sensitive resistance is The etching depth of the lead hole is The thickness of the insulating layer of the gas sensor is The thickness of the test electrode of the gas sensor and the test electrode of the humidity sensor is The material of the mass is copper, and the thickness of the mass is within 10 μm.

8. The method of claim 1, wherein, In the step S1, the silicon wafer is a single-polished N+ type <100> silicon wafer; the isolation layer is low-stress silicon nitride, and the thickness is In the step S3, the thickness of the sensitive diaphragm is In the step S4, the thickness of the sensitive resistance is 9. The method of claim 1, wherein, The gas-sensitive material of the gas sensor is SnO2 or TiO2, the humidity-sensitive material of the humidity sensor is ZnO or PEG, and the gas-sensitive material of the gas sensor and the humidity-sensitive material of the humidity sensor are obtained by spotting and applying on the test electrodes of the gas and humidity sensors.

10. A MEMS six-in-one monolithically integrated sensor, characterized by It is based on the fabrication method of the MEMS six-in-one monolithic integrated sensor according to any one of claims 1-9. It is based on the fabrication method of the MEMS six-in-one monolithic integrated sensor according to any one of claims 1-9.

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