阅读说明：本技术 集成传感器芯片 (Integrated sensor chip ) 是由 蔡春华 赵成龙 万蔡辛 何政达 蒋樱 于 2021-06-21 设计创作，主要内容包括：本公开提供了一种集成传感器芯片,其包括单晶硅基片,以及设置在单晶硅基片同一表面的加速度传感器和压力传感器,其中,该压力传感器通过谐振感测嵌入在该单晶硅基片内的密闭腔体内外气压不相等情形下,第一悬臂梁结构的弹性形变数据来测量压力；该加速度传感器包括嵌入在单晶硅基片内的运动空腔,以及贴合该运动空腔上部且位于单晶硅基片上表面的第二悬臂梁结构,该加速度传感器通过谐振感测惯性运动下第二悬臂梁结构的弹性形变数据来测量加速度。由此可提高集成传感器芯片的灵敏度,相比于传统的压阻式及电容测量方法,其精度更高,响应速度更快。(The invention provides an integrated sensor chip, which comprises a monocrystalline silicon substrate, an acceleration sensor and a pressure sensor, wherein the acceleration sensor and the pressure sensor are arranged on the same surface of the monocrystalline silicon substrate; the acceleration sensor comprises a motion cavity embedded in the single-crystal silicon substrate and a second cantilever beam structure which is attached to the upper part of the motion cavity and is positioned on the upper surface of the single-crystal silicon substrate, and the acceleration sensor measures acceleration by sensing elastic deformation data of the second cantilever beam structure under inertial motion in a resonance mode. Therefore, the sensitivity of the integrated sensor chip can be improved, and compared with the traditional piezoresistive and capacitance measuring method, the method is higher in precision and higher in response speed.)

1. An integrated sensor chip comprises a monocrystalline silicon substrate, an acceleration sensor and a pressure sensor which are arranged on the same surface of the monocrystalline silicon substrate,

the pressure sensor comprises a closed cavity embedded in the single-crystal silicon substrate and a first cantilever beam structure which is attached to the upper part of the closed cavity and is positioned on the upper surface of the single-crystal silicon substrate, a first piezoelectric film is clamped by the first cantilever beam structure, and the pressure sensor measures pressure by sensing elastic deformation data of the first cantilever beam structure under the condition that the air pressure inside and outside the closed cavity is unequal through resonance;

the acceleration sensor comprises a motion cavity embedded in the single-crystal silicon substrate and a second cantilever beam structure which is attached to the upper part of the motion cavity and is positioned on the upper surface of the single-crystal silicon substrate, a second piezoelectric film is clamped by the second cantilever beam structure, and the acceleration sensor measures acceleration by sensing elastic deformation data of the second cantilever beam structure under inertial motion through resonance.

2. The integrated sensor chip of claim 1, wherein the first cantilever beam structure comprises: a first electrode and a second electrode which are arranged oppositely, and the first piezoelectric film clamped between the first electrode and the second electrode,

one side of the first electrode is fixed on the upper surface of the single crystal silicon substrate through a patterned bonding pad, and the edge of the second electrode, which is positioned on the same side of the first electrode, is fixed on the upper surface of the single crystal silicon substrate through the patterned bonding pad.

3. The integrated sensor chip of claim 2, further comprising:

the inner side of the first composite film layer wraps the inner cavity of the closed cavity, the outer side of the first composite film layer is tightly attached to the monocrystalline silicon substrate, and the inner cavity is close to the upper portion of the first cantilever beam structure to extend and seal the inner cavity into a cavity.

4. The integrated sensor chip of claim 3, wherein the second cantilever structure comprises: a third electrode and a fourth electrode which are arranged oppositely, and the second piezoelectric film clamped between the third electrode and the fourth electrode,

one side of the third electrode is fixed on the upper surface of the single crystal silicon substrate through a patterned bonding pad, and the edge of the fourth electrode, which is positioned on the same side of the third electrode, is fixed on the upper surface of the single crystal silicon substrate through the patterned bonding pad.

5. The integrated sensor chip of claim 3, further comprising:

and the inner side of the second composite film layer is constrained into the motion cavity, and the outer side of the second composite film layer is tightly attached to the single crystal silicon substrate.

6. The integrated sensor chip of claim 4, wherein the motion cavity is embedded within the single crystal silicon substrate and sidewalls extend up to communicate with the exterior of the single crystal silicon substrate, with a motion gap around the second cantilever structure on at least one side where no bond pads are affixed.

7. The integrated sensor chip of claim 5, wherein the first composite film layer and/or the second composite film layer is a double-layer film structure, wherein the first film layer is a silicon oxide film, and the second film layer is a silicon nitride film.

8. The integrated sensor chip of claim 4, wherein the first electrode and the second electrode are of the same material and have the same thickness, and both have a smaller projected area on the first piezoelectric film than the first piezoelectric film.

9. The integrated sensor chip of claim 8, wherein the third electrode and the fourth electrode are made of the same material and have the same thickness, and the projected areas of the third electrode and the fourth electrode on the second piezoelectric film are smaller than the projected area of the second piezoelectric film.

10. The integrated sensor chip of claim 9, wherein the first electrode and the third electrode are of the same material and have the same thickness and have the same projected area, and the second electrode and the fourth electrode are of the same material and have the same thickness and have the same projected area.

Technical Field

The disclosure relates to the technical field of MEMS sensors, in particular to an integrated sensor chip of an acceleration sensor and a pressure sensor.

Background

In the fields of aerospace, industrial automation control, automotive electronics, navigation, consumer electronics, and the like, parameters such as acceleration, pressure, and the like need to be measured simultaneously. With the continuous development of the MEMS technology, the silicon micro-machining process is becoming mature, and the composite sensor integrating the silicon micro-mechanical acceleration sensor and the pressure sensor is widely used in automobile tire pressure monitoring due to its low price, high precision and suitability for mass production.

For example, in a Tire Pressure Monitoring System (TPMS), a pressure sensor installed in each tire is used to detect the tire pressure in real time, and the information of the tire pressure is fed back to a control panel for real-time display and monitoring, so as to ensure the safe operation of the vehicle. When the air pressure of the tire is too low or a leakage phenomenon exists, the system can automatically alarm. The tire is simultaneously provided with an acceleration sensor module, the acceleration sensor is used for detecting whether the automobile runs, and the automobile is moved to start immediately by utilizing the sensitivity of the acceleration sensor to the movement, enters the system self-checking and is automatically awakened. When the automobile runs at a high speed, the detection time period is automatically and intelligently determined according to the movement speed, and the safety period, the sensitive period and the dangerous period in the running process of the automobile are monitored and early-warning judgment is made through auxiliary software, so that the itinerant detection period is gradually shortened, the early-warning capability is improved, and the power consumption of a system is greatly reduced.

In some special environments (tires), the sensor system cannot be provided with a power supply due to environment or space, and the detection of the parameters cannot be performed through a conventional wired connection, so that the transmission of detection data needs to be performed in a wireless and passive manner. The wireless passive MEMS sensor system is generally based on two principles, namely an LC loop based on inductive coupling, and is used for detecting the change of the resonant frequency of the LC loop relative to a measured parameter; the second is based on the principle of surface acoustic waves. The capacitance sensor changes capacitance values by changing some key parameters (such as substrate spacing, dielectric permittivity and the like) in the MEMS capacitance structure through environmental parameters, and further changes the resonant frequency of a loop, so that the capacitance sensor is the preferred scheme for measurement. In 2005, capacitive pressure, temperature and humidity sensors were integrated by a.d.dehennnis and k.d.wise of michigan university for use in passive wireless sensor systems, but the three sensors were manufactured separately and the process was cumbersome, and a bulk silicon processing technique and a wafer bonding method were used, and the resulting sensor product was larger in volume; in 2011, a.c. mcneil et al, by missircall semiconductor corporation, succeeded in integrating capacitive pressure and temperature sensors fabricated using thin film processes, but the sensor fabrication was also cumbersome.

As can be seen from the above background, there are many reports on the manufacturing of MEMS multi-parameter sensors, in which a full-capacitive structure is used for an inductively coupled wireless passive sensor system, but generally, a product manufactured by using a bulk silicon processing process has a large volume, and various sensors cannot be manufactured in an integrated manner, so that the complicated manufacturing process also increases the cost of the final product to a certain extent.

Disclosure of Invention

In order to solve the above technical problem, the present disclosure provides an integrated sensor chip, which can be produced by using a conventional silicon wafer, has low cost and high sensitivity, and has higher precision and faster response speed compared to a conventional piezoresistive and capacitance measurement method.

The present disclosure provides an integrated sensor chip comprising a single crystal silicon substrate, and an acceleration sensor and a pressure sensor disposed on the same surface of the single crystal silicon substrate, wherein,

the pressure sensor comprises a closed cavity embedded in a single-crystal silicon substrate and a first cantilever beam structure which is attached to the upper part of the closed cavity and is positioned on the upper surface of the single-crystal silicon substrate, wherein a first piezoelectric film is clamped in the first cantilever beam structure, and the pressure sensor measures pressure by sensing elastic deformation data of the first cantilever beam structure under the condition that the air pressure inside and outside the closed cavity is unequal through resonance;

the acceleration sensor comprises a motion cavity embedded in the single-crystal silicon substrate and a second cantilever beam structure which is attached to the upper part of the motion cavity and is positioned on the upper surface of the single-crystal silicon substrate, a second piezoelectric film is clamped on the second cantilever beam structure, and the acceleration sensor measures acceleration by sensing elastic deformation data of the second cantilever beam structure under inertial motion through resonance.

Preferably, the aforementioned first cantilever structure comprises: a first electrode and a second electrode which are arranged oppositely, and the first piezoelectric film which is clamped between the first electrode and the second electrode,

one side of the first electrode is fixed on the upper surface of the single crystal silicon substrate through a patterned bonding pad, and the edge of the second electrode, which is positioned on the same side of the first electrode, is fixed on the upper surface of the single crystal silicon substrate through the patterned bonding pad.

Preferably, the aforementioned integrated sensor chip further comprises:

the inner side of the first composite film layer wraps the inner cavity of the closed cavity, the outer side of the first composite film layer is tightly attached to the monocrystalline silicon substrate, and the first composite film layer extends and is closed to form a cavity at the upper part, close to the first cantilever beam structure, of the inner cavity.

Preferably, the aforementioned second cantilever structure comprises: a third electrode and a fourth electrode which are arranged to face each other, and the second piezoelectric film which is sandwiched between the third electrode and the fourth electrode,

one side of the third electrode is fixed on the upper surface of the single crystal silicon substrate through a patterned bonding pad, and the edge of the fourth electrode, which is positioned on the same side of the third electrode, is fixed on the upper surface of the single crystal silicon substrate through the patterned bonding pad.

Preferably, the aforementioned integrated sensor chip further comprises:

and the inner side of the second composite film layer is constrained into the motion cavity, and the outer side of the second composite film layer is tightly attached to the single crystal silicon substrate.

Preferably, the motion cavity is embedded in the monocrystalline silicon substrate, the side wall of the motion cavity extends upwards to communicate with the outside of the monocrystalline silicon substrate, and a motion gap is formed at least on one side of the periphery of the second cantilever structure where the bonding pad is not fixed.

Preferably, the first composite film layer and/or the second composite film layer is a double-layer film structure, the first film layer is a silicon oxide film, and the second film layer is a silicon nitride film.

Preferably, the first electrode and the second electrode are made of the same material and have the same thickness, and the projection areas of the first electrode and the second electrode on the first piezoelectric film are smaller than the projection area of the first piezoelectric film.

Preferably, the third electrode and the fourth electrode are made of the same material and have the same thickness, and the projected areas of the third electrode and the fourth electrode on the second piezoelectric film are smaller than the projected area of the second piezoelectric film.

Preferably, the first electrode and the third electrode are made of the same material and have the same thickness, and the projected areas of the first electrode and the third electrode are equal, and the second electrode and the fourth electrode are made of the same material and have the same thickness, and the projected areas of the second electrode and the fourth electrode are equal.

The beneficial effects of this disclosure are: the utility model provides an integrated sensor chip, it includes single crystal silicon substrate, and set up acceleration sensor and the pressure sensor at single crystal silicon substrate coplanar, wherein, this pressure sensor is including the airtight cavity of embedding in single crystal silicon substrate, and laminate this airtight cavity upper portion and lie in the first cantilever beam structure of single crystal silicon substrate upper surface, this first cantilever beam structure centre gripping has first piezoelectric film, this pressure sensor measures pressure through the elastic deformation data of the first cantilever beam structure under the unequal situation of the inside and outside atmospheric pressure of the aforementioned airtight cavity of resonance sensing, this pressure sensor is built on the airtight cavity structural foundation of silicon, this airtight cavity structure is formed through growing bilayer membrane structure, sealing performance is good, high reliability, simultaneously with CMOS's chip technology can be fine compatible, be convenient for manufacturing.

The integrated sensor chip provided by the disclosure comprises a pressure sensor and an acceleration sensor which are integrated in one chip, and the size of a sensor module can be effectively reduced, wherein the structural design of the acceleration sensor adopts the monolithic integration of a composite membrane cantilever beam structure and a cavity structure, so that high-precision measurement can be better realized, and compared with the traditional piezoresistive and capacitance measurement method, the integrated sensor chip has higher precision and faster response speed. The pressure difference formed by the closed cavity of the pressure sensor inside and outside the closed cavity is reflected on the elastic deformation data of the first cantilever beam structure, the measurement of the pressure change value is realized through the sensing of the resonant frequency, and the sensitivity is high. And because the two sensors are positioned in the same chip, and the environments of the pressure sensor and the acceleration sensor are the same, the measurement data of the pressure sensor can also be used as the temperature compensation of the measurement data of the acceleration sensor to calibrate the acceleration sensor, and the measurement precision of the acceleration sensor is further improved

In addition, the integrated sensor chip provided by the disclosure can be produced based on a traditional silicon wafer, is low in cost and has high sensitivity.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of the embodiments of the present disclosure with reference to the accompanying drawings.

Fig. 1 shows a schematic structural diagram of an integrated sensor chip provided in an embodiment of the present disclosure;

FIG. 2 illustrates a top view block diagram of the integrated sensor chip shown in FIG. 1;

FIG. 3 shows a schematic cross-sectional structure of the integrated sensor chip of FIG. 1 taken along the dashed cut line of FIG. 2;

FIG. 4 shows a schematic flow diagram of a method of making the integrated sensor chip of FIG. 1;

fig. 5a to 5h respectively show schematic cross-sectional views of structures formed at various process stages of the method for manufacturing the integrated sensor chip shown in fig. 3.

Detailed Description

To facilitate an understanding of the present disclosure, the present disclosure will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present disclosure are set forth in the accompanying drawings. However, the present disclosure may be embodied in different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

When a layer, a region, or a region is referred to as being "on" or "over" another layer, another region, or a region may be directly on or over the other layer, the other region, or another layer or a region may be included between the layer and the other layer or the other region. And, if the device is turned over, that layer, region, or regions would be "under" or "beneath" another layer, region, or regions.

If for the purpose of describing the situation directly above another layer, another region, the expression "a directly above B" or "a above and adjacent to B" will be used herein. In the present application, "a is directly in B" means that a is in B and a and B are directly adjacent, rather than a being in a doped region formed in B.

Unless otherwise specified below, various layers or regions of a semiconductor device may be composed of materials well known to those skilled in the art. Semiconductor materials include, for example, group III-V semiconductors such as GaAs, InP, GaN, SiC, and group IV semiconductors such as Si, Ge. The electrode layer may be formed of various conductive materials such as a metal layer, a doped polysilicon layer, or a laminated conductor including a metal layer and a doped polysilicon layer, or other conductive materials such as TaC, TiN, TaSiN, HfSiN, TiSiN, TiCN, TaAlC, TiAlN, TaN, PtSix, Ni3Si, Pt, Ru, W, and combinations of the various conductive materials.

In the present application, the term "semiconductor structure" refers to the general term for the entire semiconductor structure formed in the various steps of manufacturing a semiconductor device, including all layers or regions that have been formed. The term "laterally extending" refers to extending in a direction substantially perpendicular to the depth direction of the trench.

It is known that a tire pressure sensor chip (hereinafter referred to as a tire pressure sensor) is a core part of the whole TPMS system, and mainly includes a pressure sensor for monitoring the pressure in the tire and an acceleration sensor as a trigger switch. The tire pressure sensor is combined with a peripheral circuit, an MCU processor and an RF radio frequency module, so that the pressure signal in the tire can be wirelessly transmitted to a display terminal, a driver can check the pressure condition of the tire in real time, and an alarm is given when the tire pressure is abnormal. The specific working process of the tire pressure sensor is as follows: when the tire is static, the tire pressure monitoring is not needed, and the pressure sensor is in a closed state; when the tire starts to rotate, the acceleration sensor detects the centrifugal acceleration of the tire, a signal is sent out to enable the MCU to start the pressure sensor, the pressure sensor detects the tire pressure in real time and transmits data to the display terminal through the RF chip, and therefore transmission of the detection data is conducted in a wireless and passive mode.

Although there are many reports on the current MEMS multi-parameter sensor, in which a full capacitive structure is used for an inductively coupled wireless passive sensor system, generally, a product manufactured by using a bulk silicon processing technology has a large volume, and various sensors cannot be manufactured in an integrated manner, so that the complicated manufacturing process also increases the cost of the final product to a certain extent.

Based on this, the embodiments of the present disclosure provide an integrated sensor chip, which can be produced by using a conventional silicon wafer, and has low cost and high sensitivity, and compared with a conventional piezoresistive and capacitance measurement method, the integrated sensor chip has higher precision and faster response speed.

The present disclosure is described in detail below with reference to the accompanying drawings.

Fig. 1 illustrates a schematic structural diagram of an integrated sensor chip provided by an embodiment of the present disclosure, fig. 2 illustrates a top structural diagram of the integrated sensor chip illustrated in fig. 1, and fig. 3 illustrates a schematic structural cross-sectional diagram of the integrated sensor chip illustrated in fig. 1 taken along a dashed-line cutting line illustrated in fig. 2.

Referring to fig. 1 to fig. 3, an integrated sensor chip 100 provided in the embodiment of the present disclosure may be, for example, a single silicon chip integrated chip of an acceleration sensor and a pressure sensor, and hereinafter, a chip integrated with these two sensors is also described as an example, although this embodiment is not limited thereto, a sensor with different functions may also be integrated, and in other alternative embodiments, more than two sensors may also be integrated, for example, the integrated sensor chip further includes a temperature sensor (not shown), and a corresponding structure is adjusted by controlling a manufacturing process, which is not limited herein.

The MEMS micromachining is used for preparing the integrated sensor chips in batches, so that the integration level of the tire pressure sensor is improved, low cost, high yield and the like can be realized, the integrated sensor chips are applied to a Tire Pressure Monitoring System (TPMS), the real-time monitoring of the tire pressure in the driving process of an automobile can be effectively realized, and the alarm is given to the tire leakage, the low pressure and the ultrahigh pressure so as to ensure the driving safety.

As shown in fig. 1 to fig. 3, the integrated sensor chip 100 includes a monocrystalline silicon substrate 101, and an acceleration sensor 110 and a pressure sensor 120 disposed on the same surface of the monocrystalline silicon substrate 101, wherein the pressure sensor 110 includes a sealed cavity 1101 embedded in the monocrystalline silicon substrate 101, and a first cantilever structure attached to an upper portion of the sealed cavity 1101 and located on an upper surface of the monocrystalline silicon substrate 101, the first cantilever structure holds a first piezoelectric film 1061, and the pressure sensor 110 measures pressure by sensing elastic deformation data of the first cantilever structure under the condition that air pressures inside and outside the sealed cavity 1101 are not equal through resonance.

The diaphragm type pressure sensor 110 basically has the first piezoelectric film 1061 as a resonance element, and the excitation source (the difference in internal and external pressures of the sealed cavity 1101) causes the mechanical resonance frequency of the first piezoelectric film 1061 to coincide with (resonate) the excitation frequency. When the input pressure to be measured (in this embodiment, the difference between the internal pressure and the external pressure formed by the sealed cavity 1101 when the pressure to be measured is changed in the environment) is changed, the first piezoelectric film 1061 in the first cantilever structure is bent to generate a large deflection, so that the natural frequency of the first piezoelectric film changes, and the frequency characteristic that the resonance frequency changes with the pressure is sensed by the upper and lower electrodes, and then the detected pressure value can be obtained by detecting the characteristic by a detection circuit (not shown, in this embodiment, connected to the integrated sensor chip 100 through a signal).

The acceleration sensor 120 includes a motion cavity 1201 embedded in the single crystal silicon substrate 101, and a second cantilever structure attached to the upper portion of the motion cavity 1201 and located on the upper surface of the single crystal silicon substrate 101, the second cantilever structure holds a second piezoelectric film 1062, and the acceleration sensor 120 measures acceleration by resonance sensing of elastic deformation data of the second cantilever structure under inertial motion.

The resonant acceleration sensor 120 is a typical inertial device, and utilizes the force-frequency relationship of the vibrating beam (in this embodiment, the second cantilever structure), the amount of change of the resonant frequency is proportional to the acceleration, and the magnitude of the acceleration is obtained by detecting the resonant frequency. The resonant acceleration sensor 120 is always in a resonant state, and the energy carried by the resonant frequency signal is higher than the energy carried by other signals, so that the influence of other non-resonant signals on the sensor can be reduced, and the signal-to-noise ratio of the sensor can be improved.

In this embodiment, as shown in fig. 2 and fig. 3, the first cantilever structure includes: a first electrode 1051 and a second electrode 1071 which are provided to face each other, and the first piezoelectric film 1061 which is sandwiched between the first electrode 1051 and the second electrode 1071,

one side of the first electrode 1051 is fixed on the upper surface of the single crystal silicon substrate 101 by a patterned bonding pad 1081, and the edge of the second electrode 1071 on the same side as the first electrode 1051 is fixed on the upper surface of the single crystal silicon substrate 101 by a patterned bonding pad 1082.

Further, the second cantilever structure includes: a third electrode 1052 and a fourth electrode 1072 which are arranged to face each other, and the second piezoelectric film 1062 which is sandwiched between the third electrode 1052 and the fourth electrode 1072,

one side of the third electrode 1052 is fixed to the upper surface of the single-crystal silicon substrate 101 by a patterned bonding pad 1083, and the edge of the fourth electrode 1072 on the same side of the third electrode 1052 is fixed to the upper surface of the single-crystal silicon substrate 101 by a patterned bonding pad 1084.

In this embodiment, the integrated sensor chip 100 further includes: and a first composite film (not shown) which wraps the inner cavity of the closed cavity 1101 at the inner side and is closely attached to the monocrystalline silicon substrate 101 at the outer side, and which extends and closes the inner cavity near the upper part of the first cantilever structure to form a cavity.

Further, the integrated sensor chip 100 further includes: a second composite film (not shown) having an inner side confined to the motion cavity 1201 and an outer side closely fitting the monocrystalline silicon substrate 101.

Further, the motion cavity 1201 is embedded in the single crystal silicon substrate 101 and the sidewall extends to communicate with the outside of the single crystal silicon substrate 101, and there is a motion gap 1202 (as shown in fig. 1 and 3) at least on one side of the periphery of the second cantilever structure where no pad is fixed.

In this embodiment, the first composite film layer and/or the second composite film layer is a double-layer structure, in which the first film 103 is a silicon oxide film, and the second film 104 is a silicon nitride film.

In this embodiment, the double-layer composite film (the first composite film/the second composite film) is easily controlled by the conventional CMOS process, has good sealing performance, and has little influence on sensing pressure and acceleration of the cantilever structure for measuring the resonant frequency, which is more beneficial to improving the sensitivity and accuracy of measurement.

Further, as shown in fig. 2, the first electrode 1051 and the second electrode 1071 are made of the same material and have the same thickness, and the projected areas of the first electrode 1051 and the second electrode 1071 on the first piezoelectric film 1061 are smaller than the projected area of the first piezoelectric film 1061. In this embodiment, the projected areas of the first electrode 1051 and the second electrode 1071 may be equal or unequal, and are not limited herein.

Further, the third electrode 1052 and the fourth electrode 1072 are made of the same material and have the same thickness, and the projected areas of the third electrode and the fourth electrode on the second piezoelectric film 1062 are smaller than the projected area of the second piezoelectric film 1062.

Furthermore, the first electrode 1051 and the third electrode 1052 are made of the same material and have the same thickness, and the projected areas of the first electrode 1051 and the third electrode 1052 are equal, the second electrode 1071 and the fourth electrode 1072 are made of the same material and have the same thickness, and the projected areas of the second electrode 1071 and the fourth electrode 1072 are equal, so that the temperature compensation calibration of the pressure sensor 110 on the acceleration sensor 120 can be realized, the influence of the non-resonant frequency signal on the measurement result is avoided, and the influence of the independent factors (material, thickness and size) on the test sensitivity is also passed, therefore, in the two sensors in the same temperature environment, the temperature coefficient of the acceleration sensor 120 can be compensated by the measurement data of the pressure sensor 110, the calibration on the measurement data of the acceleration sensor 120 is realized, and the measurement accuracy of the integrated sensor chip 100 is further improved.

The pressure sensor 110 is built on the basis of a silicon closed cavity structure, the closed cavity 1101 structure is formed by growing a double-layer film (103 and 104) structure, the sealing performance is good, the reliability is high, and meanwhile, the pressure sensor is compatible with a CMOS chip process well and is convenient to produce and manufacture.

The integrated sensor chip 100 adopts monolithic integration of a composite membrane (piezoelectric structural formula) cantilever beam structure and a cavity structure, can better realize high-precision measurement, and has higher precision and faster response speed compared with the traditional piezoresistive and capacitance measurement method.

Fig. 4 shows a schematic flow diagram of a method for manufacturing the integrated sensor chip shown in fig. 1, and fig. 5a to 5h respectively show schematic cross-sectional views of structures formed at various process stages of the method for manufacturing the integrated sensor chip shown in fig. 3.

The entire process of fabricating the single silicon integrated chip of the acceleration sensor 120 and the pressure sensor 110 may be processed by micro-machining using the same set of photolithography mask. Referring to fig. 4 to 5h, the preferred implementation steps are as follows:

step 110: a plurality of release windows arranged along the same direction are respectively etched on the surface of the substrate in two regions.

In step 110, a single crystal silicon substrate 101 with an n-type (100) crystal plane is used as a substrate, and two regions i and ii are divided from one surface of the single crystal silicon substrate 101, wherein the region i is used for forming a pressure sensor, and the region ii is used for forming an acceleration sensor. A plurality of grid strip-shaped release windows are manufactured on a monocrystalline silicon substrate 101 at equal intervals along the <100> crystal direction of the monocrystalline silicon substrate with the n-type (100) crystal plane by utilizing an anisotropic etching process (such as reactive ion etching RIE), two groups of release windows formed in two areas are etched to the depths of a required motion cavity and a closed cavity respectively, as shown in fig. 5a, the width of each release window can be 1-2 μm, and the depth is 10 μm.

Step 120: cavities embedded in the substrate are correspondingly formed in the two regions.

In step 120, the substrate is isotropically etched while protecting the sidewall of the release window, and the sidewall of the release window may be protected by depositing a passivation material in the release window by LPCVD to form a sidewall passivation protection layer, for example, by depositing low-stress silicon nitride and silicon oxide sequentially by LPCVD, or depositing low-stress silicon nitride directly by LPCVD, thereby forming a sidewall passivation protection layer. And then, using a KOH solution or a TMAH solution to laterally etch the monocrystalline silicon substrate 101, so as to respectively communicate the bottoms of the release windows under the region I to form a cavity 102, and communicate the bottoms of the release windows under the region II to form a cavity 102, so as to subsequently manufacture a motion cavity and a pressure cavity embedded in the monocrystalline silicon substrate 101, as shown in FIG. 5 b.

Step 130: and forming a silicon oxide film on the surface of the cavity of the substrate.

In step 130, a silicon oxide film 103 is formed on the surface of the cavity 102 in the single-crystal silicon substrate 101 by an LPCVD deposition process, as shown in fig. 5 c.

Step 140: and forming a silicon nitride film on the surface of the cavity of the substrate to form a sealed cavity.

In step 140, a silicon nitride film 103 is formed on the surface of the silicon oxide film 103 in the cavity 102 of the single-crystal silicon substrate 101 by LPCVD deposition process and a release window is sewn to complete the sealing of the pressure cavity in the pressure sensor, and then, the silicon nitride excess on the surface of the silicon is removed by using silicon deep reactive ion etching technique, as shown in fig. 5 d. The cavity is formed to have a height of about 5 μm, and the surface of the single crystal silicon substrate 101 is smoothed by a polishing process such as chemical mechanical polishing CMP.

Step 150: and growing a first metal layer to form a piezoelectric structure lower electrode and a bonding pad.

In step 150, a first metal layer (e.g., aluminum) is grown on the single crystal silicon substrate 101, the metal is patterned in regions I and II, respectively, an aluminum film is sputtered and formed to form the piezoelectric structure lower electrode (the first electrode 1051 in the first cantilever structure and the third electrode 1052 in the second cantilever structure) and the corresponding pads (1081 and 1083), as shown in FIG. 5 e.

Step 160: and growing a piezoelectric material to form a piezoelectric film.

In step 160, a piezoelectric material (e.g. aluminum nitride) is grown on the first electrode 1051 and the third electrode 1052, respectively, and then photolithography and etching are performed to form a piezoelectric layer structure of the first piezoelectric film 1061 and the second piezoelectric film 1062, respectively, as shown in fig. 5 f.

Step 170: and growing a second metal layer to form an upper electrode and a bonding pad of the piezoelectric structure.

In step 170, a second metal layer (e.g., aluminum) is patterned in regions i and ii by growing a second metal layer on the first and second piezoelectric films 1061 and 1062, respectively, sputtering the aluminum film and forming piezoelectric structure upper electrodes (the second electrode 1071 in the first cantilever structure and the fourth electrode 1072 in the second cantilever structure) and corresponding pads (1082 and 1084), as shown in fig. 5 g.

Step 180: and forming a cantilever beam structure by utilizing a silicon deep reactive ion etching technology.

In step 180, a moving gap 1202 is formed in region II by anisotropic etching, such as Reactive Ion Etching (RIE), to connect the cavity 102 embedded in the single crystal silicon substrate 101 to the outside, releasing the formation of the second cantilever structure, and simultaneously forming a moving cavity 1201, as shown in FIG. 5 h. Thereby forming pressure sensor 110 in region i and sensor 120 in region ii.

Thereby completing the fabrication of the entire integrated sensor chip 100.

And finally scribing and testing.

Optionally, after the step of releasing the cantilever beam structure, a cover plate silicon wafer with a concave cavity may be further manufactured, and the cover plate silicon wafer is adhered to the single crystal silicon substrate by using bcb (benzocyclobutene) glue, so that the concave cavity of the cover plate silicon wafer and the motion cavity form a closed cavity, thereby protecting the surface structure of the integrated sensor chip.

As can be seen from fig. 1 to fig. 3 and fig. 5h, all functional components on the integrated sensor chip 100 are located on one side of a single chip, the other side of the single chip does not participate in the process, and the processed chip is convenient to package, has the characteristics of small size, low cost, high sensitivity, good stability, good precision and the like, and is suitable for mass production.

It should be noted that, although the embodiments are described and illustrated separately in the disclosure, but related to partially common techniques, it will be apparent to those skilled in the art that substitutions and integrations between the embodiments may be made, and reference may be made to one of the embodiments without explicit mention, to another embodiment described.

Further, in this document, the contained terms "include", "contain" or any other variation thereof are intended to cover a non-exclusive inclusion, so that a process, a method, an article or an apparatus including a series of elements includes not only those elements but also other elements not explicitly listed or inherent to such process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present disclosure, and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention as herein taught are within the scope of the present disclosure.