CN113607308B - Integrated sensor chip - Google Patents
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- CN113607308B CN113607308B CN202110685322.4A CN202110685322A CN113607308B CN 113607308 B CN113607308 B CN 113607308B CN 202110685322 A CN202110685322 A CN 202110685322A CN 113607308 B CN113607308 B CN 113607308B
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- G—PHYSICS
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- G01L1/00—Measuring force or stress, in general
- G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
- G01L1/162—Measuring force or stress, in general using properties of piezoelectric devices using piezoelectric resonators
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
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Abstract
The present disclosure provides an integrated sensor chip, which comprises a monocrystalline silicon substrate, and an acceleration sensor and a pressure sensor which are arranged on the same surface of the monocrystalline silicon substrate, wherein the pressure sensor measures pressure by resonance sensing elastic deformation data of a first cantilever structure under the condition that the internal and external air pressures of a closed cavity embedded in the monocrystalline silicon substrate are unequal; the acceleration sensor comprises a motion cavity embedded in the monocrystalline silicon substrate and a second cantilever structure attached to the upper part of the motion cavity and positioned on the upper surface of the monocrystalline silicon substrate, and the acceleration sensor measures acceleration by sensing elastic deformation data of the second cantilever structure under inertial motion through resonance. Therefore, the sensitivity of the integrated sensor chip can be improved, and compared with the traditional piezoresistive and capacitive measuring method, the method has higher precision and higher response speed.
Description
Technical Field
The disclosure relates to the technical field of MEMS sensors, in particular to an integrated sensor chip of an acceleration and 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-mechanical processing technology is mature, and the composite sensor integrating the silicon micro-mechanical acceleration sensor and the pressure sensor is widely applied to the automobile tire pressure monitoring due to low price, high precision and suitability for mass production.
For example, in a tire pressure detection system (TPMS) of an automobile, pressure sensors installed in each tire are utilized to detect the tire pressure in real time, and information of the tire pressure is fed back to a control panel for real-time display and monitoring, so that safe running of the automobile is ensured. When the tire pressure is too low or leakage occurs, the system can automatically alarm. The tire is provided with an acceleration sensor module at the same time, the acceleration sensor is used for detecting whether the automobile is running, and the sensitivity of the acceleration sensor to motion is utilized to realize the instant starting of the automobile when the automobile is moving, and the system is self-checked and automatically wakened. 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 tour detection period is gradually shortened, the early warning capability is improved, and the system power consumption is greatly reduced.
In some special environments (tires), the sensor system cannot be powered for environmental or space reasons, and the detection of parameters cannot be performed through a conventional wired connection, requiring the transmission of detection data in a wireless passive manner. Wireless passive MEMS sensor systems are generally based on two principles, one being based on an inductively coupled LC loop, detecting a change in its resonant frequency with respect to a measured parameter; and secondly, the principle based on surface acoustic waves. The former changes the capacitance value by changing some key parameters (such as the substrate spacing, dielectric permittivity, etc.) in the MEMS capacitance structure through environmental parameters, so as to change the resonant frequency of the loop, so that the capacitive sensor is the preferred scheme for measurement. In 2005, capacitive pressure, temperature and humidity sensors are integrated by a d.de hennis and a k.d.wise of michigan university and are used for passive wireless sensor systems, but three sensors are manufactured respectively, the process is complicated, a bulk silicon processing technology and a wafer bonding method are used, and the manufactured sensor product has a larger volume; in the recent 2011, a.c. mcneil et al, from femtocar semiconductors, successfully integrated capacitive pressure and temperature sensors fabricated using thin film processes, but the sensor fabrication was also cumbersome.
As can be seen from the above study background, there are many reports on the fabrication of MEMS multi-parameter sensors, in which a fully capacitive structure is not used for an inductively coupled wireless passive sensor system, but in general, the volume of a product manufactured by using a bulk silicon processing technology is large, and the integrated fabrication of various sensors cannot be realized, so that the complicated fabrication process also increases the cost of the final product to some extent.
Disclosure of Invention
In order to solve the technical problems, the present disclosure provides an integrated sensor chip, which can be produced by adopting a traditional silicon wafer, has low cost and higher sensitivity, and has higher precision and faster response speed compared with the traditional piezoresistive and capacitance measuring methods.
The present disclosure provides an integrated sensor chip comprising a monocrystalline silicon substrate, and an acceleration sensor and a pressure sensor disposed on the same surface of the monocrystalline silicon substrate, wherein,
the pressure sensor comprises a closed cavity embedded in the monocrystalline silicon substrate and a first cantilever structure attached to the upper part of the closed cavity and positioned on the upper surface of the monocrystalline silicon substrate, wherein the first cantilever structure is used for clamping a first piezoelectric film, and the pressure sensor is used for measuring pressure by sensing elastic deformation data of the first cantilever structure under the condition that the internal and external air pressures of the closed cavity are unequal through resonance;
the acceleration sensor comprises a motion cavity embedded in the monocrystalline silicon substrate, and a second cantilever structure attached to the upper part of the motion cavity and positioned on the upper surface of the monocrystalline silicon substrate, wherein the second cantilever structure is clamped with a second piezoelectric film, and the acceleration sensor measures acceleration by sensing elastic deformation data of the second cantilever structure under inertial motion through resonance.
Preferably, the first cantilever structure includes: a first electrode and a second electrode arranged opposite to each other, the first piezoelectric film sandwiched between the first electrode and the second electrode,
one side of the first electrode is fixed on the upper surface of the monocrystalline silicon substrate through a patterned bonding pad, and the edge of the second electrode on the same side of the first electrode is fixed on the upper surface of the monocrystalline silicon substrate through a patterned bonding pad.
Preferably, the aforementioned integrated sensor chip further comprises:
the inner side of the first composite film wraps the inner cavity of the closed cavity, the outer side of the first composite film is tightly attached to the single crystal silicon substrate, and the first composite film extends and seals the inner cavity close to the upper part of the first cantilever structure to form a cavity.
Preferably, the aforementioned second cantilever structure includes: a third electrode and a fourth electrode which are arranged oppositely, the second piezoelectric film which is clamped between the third electrode and the fourth electrode,
one side of the third electrode is fixed on the upper surface of the monocrystalline silicon substrate through a patterned bonding pad, and the edge of the fourth electrode on the same side of the third electrode is fixed on the upper surface of the monocrystalline silicon substrate through a patterned bonding pad.
Preferably, the aforementioned integrated sensor chip further comprises:
and the inner side of the second composite film layer is restrained into the movement 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 extends upwards to communicate with the exterior of the monocrystalline silicon substrate, and a motion gap is formed on at least one side, around the second cantilever structure, where the bonding pad is not fixed.
Preferably, the first composite film layer and/or the second composite film layer has a double-layer film structure, wherein the first film is a silicon oxide film, and the second film 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 area of the first electrode and the second electrode on the first piezoelectric film is 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 projection area of the third electrode and the fourth electrode on the second piezoelectric film is smaller than the projection 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 the present disclosure are: the integrated sensor chip comprises a monocrystalline silicon substrate, and an acceleration sensor and a pressure sensor which are arranged on the same surface of the monocrystalline silicon substrate, wherein the pressure sensor comprises a closed cavity embedded in the monocrystalline silicon substrate, and a first cantilever structure attached to the upper part of the closed cavity and positioned on the upper surface of the monocrystalline silicon substrate, the first cantilever structure is used for clamping a first piezoelectric film, the pressure sensor is used for measuring pressure by sensing elastic deformation data of the first cantilever structure under the condition that the internal and external air pressures of the closed cavity are unequal through resonance, the pressure sensor is established on the basis of the silicon closed cavity structure, the closed cavity structure is formed through a grown bilayer film structure, the sealing performance is good, the reliability is high, and meanwhile, the pressure sensor is compatible with a CMOS chip technology well, and is convenient to manufacture.
The integrated sensor chip provided by the disclosure comprises the pressure sensor and the acceleration sensor which are integrated in one chip, and the volume of the sensor module can be effectively reduced, wherein the structural design of the acceleration sensor adopts the monolithic integration of the composite membrane cantilever beam structure and the 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 inside and outside the closed cavity of the pressure sensor is reflected on the elastic deformation data of the first cantilever structure, and the pressure change value is measured through the sensing of the resonant frequency, so that the pressure sensor has higher sensitivity. And because the two sensors are positioned in the same chip, the environments of the pressure sensor and the acceleration sensor are the same, therefore, 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 measurement data of 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 higher 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 illustrates a schematic diagram of a structure of an integrated sensor chip provided by 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 along the dashed cut line of FIG. 2;
FIG. 4 shows a schematic flow chart of a method of fabricating the integrated sensor chip shown in FIG. 1;
fig. 5a to 5h show schematic cross-sectional views of structures formed at various process stages in the method of manufacturing the integrated sensor chip shown in fig. 3, respectively.
Detailed Description
In order that the disclosure may be understood, a more complete description of the disclosure will be rendered by reference to the appended drawings. Preferred embodiments of the present disclosure are shown in the drawings. This disclosure may, however, 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 describing the structure of a device, when a layer, an area, is referred to as being "on" or "over" another layer, another area, it can be directly on the other layer, another area, or other layers or areas can be included between the layer, another area, and the other layer, another area. And if the device is flipped, the one layer, one region, will be "under" or "beneath" the other layer, another region.
If, for the purposes of describing a situation directly on top of another layer, another region, the expression "a directly on top of B" or "a directly on top of B and adjoining it" will be used herein. In this application, "a is directly in B" means that a is in B and a is directly adjacent to B, rather than a being in the doped region formed in B.
Unless specifically indicated below, the various layers or regions of the 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 materials that are electrically conductive, such as a metal layer, a doped polysilicon layer, or a laminated conductor comprising a metal layer and a doped polysilicon layer, or other electrically conductive materials, such as TaC, tiN, taSiN, hfSiN, tiSiN, tiCN, taAlC, tiAlN, taN, ptSix, ni3Si, pt, ru, W and combinations of the various electrically conductive materials.
In this application, the term "semiconductor structure" refers to a generic term for the entire semiconductor structure formed in the various steps of fabricating a semiconductor device, including all layers or regions that have been formed. The term "laterally extending" refers to extending in a direction generally perpendicular to the direction of the depth 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 entire TPMS system, and mainly includes a pressure sensor that monitors the pressure in a tire and an acceleration sensor that is 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 wireless transmission of the pressure signals in the tire to the display terminal can be realized, 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 tire pressure sensor specifically works as follows: when the tire is stationary, 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 and sends out a signal 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 the transmission of detection data is carried out in a wireless passive mode.
Although MEMS multiparameter sensors have been reported to a large extent, in which a fully capacitive structure is not lacking for use in inductively coupled wireless passive sensor systems, in general, the volume of the product manufactured using bulk silicon processing is large, and the various sensors are not integrated, and the cumbersome manufacturing process also increases the cost of the final product to some extent.
Based on this, the embodiment of the disclosure provides an integrated sensor chip, which can be produced by adopting a traditional silicon wafer, has low cost and higher sensitivity, and has higher precision and faster response speed compared with the traditional piezoresistive and capacitance measurement methods.
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 in an embodiment of the present disclosure, fig. 2 illustrates a top view structural diagram of the integrated sensor chip illustrated in fig. 1, and fig. 3 illustrates a schematic sectional structural diagram of the integrated sensor chip illustrated in fig. 1 along a dashed cutting line illustrated in fig. 2.
Referring to fig. 1 to 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 the following description will also take a chip integrated with the two sensors as an example, which is not limited to this, but may also be integrated with other sensors with different functions, and may also be integrated with more than two sensors in other alternative embodiments, for example, the integrated sensor chip further includes a temperature sensor (not shown), where the corresponding structure is adjusted by controlling the manufacturing process, which is not limited herein.
The integrated sensor chip is prepared in batches by utilizing MEMS micromachining, 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 chip can be applied to an automobile Tire Pressure Monitoring System (TPMS), the real-time monitoring of the tire pressure in the running process of an automobile can be effectively realized, and the air leakage, the low pressure and the ultra-high pressure of the tire can be alarmed so as to ensure the running safety.
As shown in fig. 1 to 3, the integrated sensor chip 100 includes a monocrystalline silicon substrate 101, and a pressure sensor 110 and an acceleration sensor 120 disposed on the same surface of the monocrystalline silicon substrate 101, wherein the pressure sensor 110 includes a closed cavity 1101 embedded in the monocrystalline silicon substrate 101, and a first cantilever structure attached to an upper portion of the closed cavity 1101 and located on an upper surface of the monocrystalline silicon substrate 101, the first cantilever structure holding a first piezoelectric film 1061, and the pressure sensor 110 measures pressure by resonating elastic deformation data of the first cantilever structure when the internal and external air pressures of the closed cavity 1101 are not equal.
The basic principle of the diaphragm pressure sensor 110 is that the first piezoelectric film 1061 is used as a resonant element, and an excitation source (internal-external pressure difference of the sealed chamber 1101) causes the mechanical resonance frequency of the first piezoelectric film 1061 to coincide with (resonate with) the excitation frequency. When the pressure to be measured (in this embodiment, the pressure to be measured is the difference between the internal and external air pressures formed by the closed cavity 1101 when the environment changes) changes, the first piezoelectric film 1061 in the first cantilever structure bends with large deflection to change its natural frequency, so that the frequency characteristic of the resonant frequency changing 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 with the integrated sensor chip 100 by 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 an upper portion of the motion cavity 1201 and located on an upper surface of the single crystal silicon substrate 101, the second cantilever structure sandwiching a second piezoelectric film 1062, and the acceleration sensor 120 measures acceleration by sensing elastic deformation data of the second cantilever structure under inertial motion through resonance.
The resonant acceleration sensor 120 is a typical inertial device, and uses the characteristic of the relationship between the force and the frequency of the vibration beam (the second cantilever structure in this embodiment), the variation 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 3, the first cantilever structure includes: a first electrode 1051 and a second electrode 1071 disposed opposite to each other, and the first piezoelectric film 1061 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 through 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 through a patterned bonding pad 1082.
Further, the second cantilever structure includes: a third electrode 1052 and a fourth electrode 1072 disposed opposite to each other, and the second piezoelectric film 1062 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 through a patterned pad 1083, and the edge of the fourth electrode 1072 on the same side as the third electrode 1052 is fixed to the upper surface of the single crystal silicon substrate 101 through a patterned pad 1084.
In this embodiment, the integrated sensor chip 100 further includes: a first composite film (not shown), the inner side of which wraps the inner cavity of the closed cavity 1101, the outer side of which is closely attached to the single crystal silicon substrate 101, and which extends to close the upper portion of the first cantilever structure in the inner cavity to form a cavity.
Further, the aforementioned integrated sensor chip 100 further includes: a second composite film (not shown) having an inner side constrained to the motion cavity 1201 and an outer side closely adhering to the single crystal silicon substrate 101.
Further, the aforementioned motion cavity 1201 is embedded in the monocrystalline silicon substrate 101 and the sidewall extends upward to communicate with the exterior of the monocrystalline silicon substrate 101, and there is a motion gap 1202 (shown in fig. 1 and 3) around the aforementioned second cantilever structure on at least one side where no bond pad is fixed.
In this embodiment, the first composite film layer and/or the second composite film layer has a dual-layer structure, 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 easy to be 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, thereby being 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 area of the first electrode 1051 and the projected area of 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 projection areas of the first electrode 1051 and the second electrode 1071 may be equal or unequal, and the present invention is not limited thereto.
Further, the third electrode 1052 and the fourth electrode 1072 are of the same material and have the same thickness, and the projected area of both on the second piezoelectric film 1062 is smaller than the projected area of the second piezoelectric film 1062.
Further, 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 1072 and the fourth electrode are equal, so that the temperature compensation calibration of the pressure sensor 110 on the acceleration sensor 120 can be realized, the influence of non-resonant frequency signals on the measurement result is avoided, and meanwhile, the influence of irrelevant factors (materials, thickness and size) on the test sensitivity is avoided, so that in two sensors in the same temperature environment, the compensation of the measurement data of the pressure sensor 110 on the temperature coefficient of the acceleration sensor 120 can be realized, the calibration of 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 based on a silicon closed cavity structure, the closed cavity 1101 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 well compatible with a CMOS chip technology, and is convenient to produce and manufacture.
The integrated sensor chip 100 adopts the monolithic integration of a composite membrane (piezoelectric structure type) 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 producing the integrated sensor chip shown in fig. 1, and fig. 5a to 5h show schematic cross-sectional views of structures formed at various process stages in the method for producing the integrated sensor chip shown in fig. 3, respectively.
The entire process of manufacturing the single silicon integrated chip of the acceleration sensor 120 and the pressure sensor 110 can be processed by micro-mechanical process using the same set of photolithography. Referring to fig. 4-5 h, the preferred implementation steps are as follows:
step 110: and etching a plurality of release windows which are arranged along the same direction on the surface of the substrate respectively in two areas.
In step 110, the single crystal silicon substrate 101 having n-type (100) crystal plane is used as a substrate, and two areas i and ii are defined on one surface of the single crystal silicon substrate 101, the area i is used for forming a pressure sensor, the area ii is used for forming an acceleration sensor, however, the method is not limited thereto, and the area positions of the two functional sensors may be exchanged. A plurality of grid elongated release windows are fabricated on the single crystal silicon substrate 101 at equal intervals along the <100> crystal direction of the n-type (100) crystal plane by using an anisotropic etching process (e.g., reactive ion etching RIE), and two sets of release windows formed in two regions are etched to the depths of the desired motion cavity and the closed cavity, respectively, as shown in fig. 5a, the width of each release window may be 1-2 μm and the depth may be 10 μm.
Step 120: cavities embedded in the substrate are correspondingly formed in the two areas respectively.
In step 120, the sidewall of the release window of the substrate is protected by isotropic etching of the silicon, and the sidewall of the release window may be protected by LPCVD deposition of passivation material in the release window to form a sidewall passivation layer, for example, low stress silicon nitride and silicon oxide may be deposited sequentially by LPCVD, or low stress silicon nitride may be deposited directly by LPCVD to form a sidewall passivation layer. The monocrystalline silicon substrate 101 is then etched laterally with KOH solution or TMAH solution to communicate with the bottoms of the release windows under region i to form cavities 102, and with the bottoms of the release windows under region ii to form cavities 102, respectively, for subsequent fabrication of the motion cavities and pressure cavities 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: a silicon nitride film is formed on the cavity surface 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 of the cavity 102 in the monocrystalline silicon substrate 101 by an 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 deep reactive ion etching technique is used to remove the excess silicon nitride on the silicon surface, as shown in fig. 5 d. The resulting cavity is about 5 μm high 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 lower electrode of the piezoelectric structure and a bonding pad.
In step 150, a first metal layer (e.g., aluminum) is grown on the monocrystalline silicon substrate 101, the metal is patterned in regions i and ii, respectively, an aluminum film is sputtered and a piezoelectric structure lower electrode (first electrode 1051 in the first cantilever structure and third electrode 1052 in the second cantilever structure) and corresponding pads (1081 and 1083) are formed, as shown in fig. 5 e.
Step 160: the piezoelectric material is grown to form a piezoelectric film.
In step 160, the piezoelectric layer structures of the first piezoelectric film 1061 and the second piezoelectric film 1062 are formed by growing a piezoelectric material (e.g., aluminum nitride) on the first electrode 1051 and the third electrode 1052, respectively, and photolithography and etching are performed, 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, the metal is patterned in regions i and ii by growing a second metal layer (e.g., aluminum) on the first and second piezoelectric films 1061 and 1062, respectively, sputtering the aluminum film and forming the piezoelectric structure upper electrode (the second electrode 1071 in the first cantilever structure and the fourth electrode 1072 in the second cantilever structure) and the corresponding pads (1082 and 1084), respectively, 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 motion gap 1202 is formed in region II by an anisotropic etch, such as a Reactive Ion Etching (RIE) process, to communicate the cavity 102 embedded in the single crystal silicon substrate 101 to the outside, releasing the formation of a second cantilever structure, and simultaneously forming a motion cavity 1201, as shown in FIG. 5 h. In this way, a pressure sensor 110 is formed in region I, and a sensor 120 is formed in region II.
Thereby completing the fabrication of the entire integrated sensor chip 100.
Finally, scribing and testing are carried out.
Optionally, after the step of releasing the cantilever structure, a cover plate silicon wafer with a concave cavity can be manufactured, and the cover plate silicon wafer is adhered to the monocrystalline silicon substrate by using BCB (Benzo cyclo buene) glue, so that the cover plate silicon wafer elastically cantilevers, and the concave cavity and the movement cavity form a closed cavity, thereby protecting the surface structure of the integrated sensor chip.
As can be seen from fig. 1 to 3 and fig. 5h, all the functional components on the integrated sensor chip 100 are located on one surface of a single chip, the other surface of the single chip does not participate in the process, and the processed chip is convenient for packaging, and 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, in the description of the present disclosure, although the embodiments are separately illustrated and described above, the technology related to the partial sharing may be replaced and integrated between the embodiments, and reference may be made to another embodiment described in the description, for those skilled in the art, to what is not explicitly described in relation to one embodiment.
Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
Finally, it should be noted that: it is apparent that the above examples are merely illustrative of the present disclosure and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present disclosure.
Claims (10)
1. An integrated sensor chip comprises a monocrystalline silicon substrate, and an acceleration sensor and a pressure sensor which are arranged on the same surface of the monocrystalline silicon substrate, and is characterized in that,
the pressure sensor comprises a closed cavity embedded in the monocrystalline silicon substrate and a first cantilever structure attached to the upper part of the closed cavity and positioned on the upper surface of the monocrystalline silicon substrate, wherein the first cantilever structure clamps a first piezoelectric film, and the pressure sensor measures pressure by resonating frequency characteristics of resonance frequency changing along with pressure formed by elastic deformation data of the first cantilever structure under the condition that the internal and external air pressures of the closed cavity are unequal;
the acceleration sensor comprises a motion cavity embedded in the monocrystalline silicon substrate and a second cantilever structure attached to the upper portion of the motion cavity and located on the upper surface of the monocrystalline silicon substrate, the second cantilever structure clamps a second piezoelectric film, and the acceleration sensor measures acceleration by means of resonance sensing of frequency characteristics that the elastic deformation data of the second cantilever structure changes with force under inertial motion.
2. The integrated sensor chip of claim 1, wherein the first cantilever structure comprises: a first electrode, a second electrode, and a first piezoelectric film sandwiched between the first electrode and the second electrode,
one side of the first electrode is fixed on the upper surface of the monocrystalline 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 monocrystalline silicon substrate through a patterned bonding pad.
3. The integrated sensor chip of claim 2, further comprising:
the inner side of the first composite film wraps the inner cavity of the closed cavity, the outer side of the first composite film is tightly attached to the monocrystalline silicon substrate, and the first composite film extends and seals the inner cavity close to the upper portion of the first cantilever structure to form 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 oppositely arranged, 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 monocrystalline silicon substrate through a patterned bonding pad, and the edge of the fourth electrode on the same side of the third electrode is fixed on the upper surface of the monocrystalline silicon substrate through a 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 monocrystalline silicon substrate.
6. The integrated sensor chip of claim 4, wherein the motion cavity is embedded within the single crystal silicon substrate and the sidewall extends 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 pad is secured.
7. The integrated sensor chip of claim 5, wherein the first composite film layer and/or the second composite film layer has a double-layer film structure, wherein the first film is a silicon oxide film, and the second film 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 the projected area of both on the first piezoelectric film is smaller than the projected area of the first piezoelectric film.
9. The integrated sensor chip of claim 8, wherein the third electrode and the fourth electrode are of the same material and have the same thickness, and the projected area of both on the second piezoelectric film is 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 the projected areas of the two are equal, and the second electrode and the fourth electrode are of the same material and have the same thickness, and the projected areas of the two are equal.
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| CN102476786B (en) * | 2010-11-22 | 2015-01-14 | 中国科学院上海微系统与信息技术研究所 | Single silicon chip integrated chip combining acceleration sensor and pressure sensor and manufacturing method of single silicon chip integrated chip |
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