CN217133024U - MEMS capacitive humidity sensor with wafer level packaging - Google Patents
MEMS capacitive humidity sensor with wafer level packaging Download PDFInfo
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- CN217133024U CN217133024U CN202220308458.3U CN202220308458U CN217133024U CN 217133024 U CN217133024 U CN 217133024U CN 202220308458 U CN202220308458 U CN 202220308458U CN 217133024 U CN217133024 U CN 217133024U
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Abstract
The application relates to an MEMS capacitive humidity sensor with wafer level packaging, which is characterized by comprising a humidity sensor chip, wherein the upper surface of the chip comprises a humidity sensing unit; the shell comprises an upper surface and a cavity below the upper surface, the lower surface of the shell is bonded with the first packaging ring on the upper surface of the chip through a second packaging ring, and therefore a cavity is formed between the shell and the chip and at least contains the humidity sensing unit; and the shell also comprises one or more through holes penetrating through the upper surface of the shell, and the projection of the through holes on the upper surface of the chip is positioned in the range of the humidity sensing unit.
Description
Technical Field
The present application relates to the field of MEMS (micro-electro-mechanical systems) technology, and in particular, to a MEMS capacitive humidity sensor with wafer level packaging.
Background
With the development of technology, humidity is widely used in military, meteorological agriculture, industry, medical treatment, building, household appliances and the like. Various types of humidity sensors such as hair, dry and wet, dew point, resistance and the like have been researched for many years, but the humidity sensors have the defects of poor consistency, high price, large volume, poor linearity, poor hysteresis characteristic and the like.
In recent years, micro-electromechanical systems (mems) technology has become a mainstream high-tech technology by adopting advanced semiconductor manufacturing processes to realize batch manufacturing of mems devices. Humidity sensors made by MEMS technology, which are compatible with CMOS processes, are also becoming widely used because of their advantages such as good consistency, low price, small size, etc.
MEMS devices typically include at least one sensitive movable element, such as a moisture-sensitive polymer in a moisture sensor. Therefore, the sensitive components need to be protected by packaging and other technologies during the manufacturing process. Besides the sensitive parts, the mems device is electrically connected to the integrated circuit to form a complete system. Therefore, how to integrate the system is an important issue in the manufacturing process. In the conventional integration scheme, an independent micro-electromechanical device and an integrated circuit chip are firstly adjacently installed on the same substrate in the packaging process, then the two parts are electrically connected through a lead, and finally the integration is completed by packaging a tube shell. Capacitance change of the capacitance type humidity sensor is sensitive, and precision of the humidity sensor is easy to be deteriorated in the packaging process, so that performance of a device is affected.
In addition to the above problems occurring in the packaging process, the conventional semiconductor packaging equipment cannot be directly used for packaging the micro-electromechanical device, and the problem of high cost is caused by the poor compatibility with the existing semiconductor packaging test equipment; the traditional packaging technology has poor vacuum tightness and can affect the protection of sensitive components. In addition, the problems of large device packaging volume, large packaging form occupation space caused by a wire bonding process and the like exist.
Miniaturization, integration and low cost have become the inevitable trend of packaging micro-electromechanical devices, and therefore, how to solve the disadvantages of the prior art and realize a miniaturized low-cost integration scheme has become an urgent issue to be solved.
SUMMERY OF THE UTILITY MODEL
Aiming at the technical problems in the prior art, the application provides an MEMS capacitive humidity sensor with wafer level packaging, which comprises a humidity sensor chip, wherein the upper surface of the chip comprises a humidity sensing unit; the shell comprises an upper surface and a cavity below the upper surface, the lower surface of the shell is bonded with the first packaging ring on the upper surface of the chip through a second packaging ring, and therefore a cavity is formed between the shell and the chip and at least contains the humidity sensing unit; and the shell also comprises one or more through holes penetrating through the upper surface of the shell, and the projection of the through holes on the upper surface of the chip is positioned in the range of the humidity sensing unit.
In particular, the chip comprises a first substrate and an integrated circuit unit, one end of the integrated circuit unit is electrically connected with the humidity sensing unit, and the other end of the integrated circuit unit is electrically connected with an external circuit through a conductive material in a conductive through hole penetrating through the first substrate.
In particular, the chip comprises a heating structure located below the humidity sensing unit.
In particular, the chip comprises a heating structure, which is located in the same layer as the humidity sensing unit.
Particularly, the humidity sensing unit comprises a humidity sensing polymer and interdigital electrodes, wherein the interdigital electrodes are positioned on the upper surface of the chip, and the humidity sensing polymer covers the interdigital electrodes.
Particularly, the humidity sensing unit further comprises a passivation layer which is located between the humidity sensing polymer and the interdigital electrodes and covers the interdigital electrodes.
In particular, the structure of the interdigital electrode comprises a single pair of interdigital structures or a differential interdigital structure.
In particular, the housing includes a second substrate and an insulating layer located above the second substrate to form an upper surface of the housing, wherein the cavity is formed in the second substrate, and the through hole penetrates through the insulating layer.
In particular, the sum of the areas of the one or more through holes is not less than 50% of the surface area of the humidity sensing unit.
In particular, part or all of the cavity is surrounded by the second substrate.
In particular, the second substrate is a silicon substrate.
By adopting the scheme, the occupied space of the capacitive humidity sensor chip can be greatly saved, the volume of the humidity sensor is reduced, and the influence of a routing process connecting circuit on the chip is reduced. In addition, the capacitive humidity sensor chip design that this application adopted can also protect humidity sensing unit, keeps apart humidity-sensitive medium and circuit when integrated sensor and circuit, ensures the device performance, improves capacitive humidity sensor's the degree of accuracy.
Drawings
Preferred embodiments of the present application will now be described in further detail with reference to the accompanying drawings, in which:
FIG. 1A is a cross-sectional schematic view of a MEMS capacitive humidity sensor with wafer level packaging according to one embodiment of the present application;
FIG. 1B is a schematic diagram of the overall structure of a MEMS capacitive humidity sensor with wafer level packaging according to one embodiment of the present application;
FIG. 2 is a cross-sectional schematic view of a humidity sensor chip in a MEMS capacitive humidity sensor with wafer level packaging according to one embodiment of the present application;
fig. 3A-B are schematic diagrams of interdigital electrode structures of a humidity sensor chip in a wafer-level packaged MEMS capacitive humidity sensor in accordance with various embodiments of the present application; and
FIG. 4 is a cross-sectional schematic view of a housing in a MEMS capacitive humidity sensor with wafer level packaging according to one embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof and in which is shown by way of illustration specific embodiments of the application. In the drawings, like numerals describe substantially similar components throughout the different views. Various specific embodiments of the present application are described in sufficient detail below to enable those skilled in the art to practice the teachings of the present application. It is to be understood that other embodiments may be utilized and structural, logical or electrical changes may be made to the embodiments of the present application. In this context, "above" or "below" may refer to a relative positional relationship of upper and lower that may or may not be in contact with each other.
FIG. 1A is a cross-sectional schematic view of a MEMS capacitive humidity sensor with wafer level packaging according to one embodiment of the present application. As shown in fig. 1A, the MEMS capacitive humidity sensor with wafer level package includes a humidity sensor chip 10a and a housing 10b bonded to each other using a wafer level alignment bonding technique, and a cavity formed by bonding the humidity sensor chip 10a and the housing 10 b. According to various embodiments, the wafer bonding technique may employ metal bonding, glass bonding, and the like.
According to one embodiment, as shown in fig. 1A, the humidity sensor chip 10a is used for sensing the external humidity change and converting the humidity change into an electrical signal to be transmitted to an external circuit through the integrated circuit. The humidity sensor chip 10a includes a humidity sensing unit 23 for contacting the air to be measured and a first packaging ring 24, wherein the first packaging ring 24 is used for bonding the humidity sensor chip 10a and the housing 10 b. Wherein, the humidity sensing unit 23 is located in a cavity generated by bonding the humidity sensor chip 10a and the housing 10 b.
According to one embodiment, the housing 10b is located above the humidity sensor chip 10a, and protects sensitive devices in the humidity sensing unit while ensuring that the humidity sensing unit 23 is in contact with air. Housing 10b includes at least cavity 402, through-hole 404 above cavity 402, and second encapsulation ring 41. The cavity 402 forms a cavity with the upper surface of the humidity sensor chip 10a after the humidity sensor chip 10a and the case 10b are bonded.
FIG. 1B is a schematic diagram of the overall structure of a MEMS capacitive humidity sensor with wafer level packaging according to one embodiment of the present application.
According to one embodiment of the present application, as shown in fig. 1B, air is in contact with the humidity sensing unit (not shown) through the through-hole 404 of the surface of the housing 10B. When the humidity in the air changes, the humidity sensing unit generates a capacitance change accordingly, and the capacitance change value is converted into an electrical signal by a CMOS integrated circuit unit (not shown) in the humidity sensor chip 10a and transmitted to an external circuit through the metal ball 227. The projection of the cavity 402 above the housing 10b can cover the humidity sensing unit, so the housing 10b can protect the humidity sensing unit 23 on the humidity sensor chip 10 a.
According to one embodiment, the humidity sensor chip 10a and the housing 10b are closely attached by bonding the first package ring 24 and the second package ring 41.
FIG. 2 is a cross-sectional view of a humidity sensor chip in a MEMS capacitive humidity sensor with wafer level packaging according to various embodiments of the present application.
As shown in fig. 2, the humidity sensor chip 10a includes at least a substrate 20, and a CMOS integrated circuit unit 22 located above the substrate 20. According to one embodiment, the upper surface of the substrate serves as a first surface 201, the lower surface of the CMOS integrated circuit unit 22 is coupled and fixed to the first surface 201, and the lower surface of the substrate 20 serves as a second surface 202.
According to one embodiment, the humidity sensor chip 10a further includes at least a humidity sensing unit 23 located above the CMOS integrated circuit unit 22 and a first package ring 24 located on the same plane as the humidity sensing unit 23. Wherein the first encapsulating ring 24 is used for bonding with the housing 10 b.
According to one embodiment, the humidity sensing unit 23 includes at least the interdigital electrode 231 constituting a capacitor, and the humidity sensing polymer 232 disposed above the interdigital electrode 231 and covering the interdigital electrode 231 for sensing a humidity change in contact with air.
According to one embodiment, the material of the wetness sensing polymer 232 may include polyimide PI, and may also include other dielectric constant wetness sensitive materials.
Fig. 3A-B are schematic diagrams of interdigital electrode structures of a humidity sensor chip in a MEMS capacitive humidity sensor with wafer level packaging according to various embodiments of the present application. According to the embodiment of the present application, the structure of the interdigital electrode 231 may be a single pair of interdigital structures, as shown in fig. 3A, or a differential interdigital structure, as shown in fig. 3B.
According to different embodiments, the shape, number and arrangement of the interdigital strips can be changed according to actual needs. The material of the interdigital electrode 231 includes aluminum, copper, titanium, gold, tungsten, polysilicon, or the like, and may be formed by a sputtering process or the like.
According to one embodiment, the humidity sensing unit 23 may further include a passivation layer 223. The passivation layer 223 covers the surface of the interdigital electrode 231, and plays a role in protecting the interdigital electrode, preventing the interdigital electrode from contacting moisture to influence the operation of the device, and ensuring the measurement accuracy. According to an embodiment, the material of the passivation layer 223 may include silicon nitride.
According to one embodiment, the humidity sensor chip 10a may further include an insulating layer 222 for isolating the CMOS integrated circuit unit 22 and the humidity sensing unit 23 to reduce interference caused by moisture. According to one embodiment, the material of the insulating layer 222 may include silicon oxide.
As shown in fig. 2, the humidity sensor chip 10a may further include a heating structure 221 for heating the humidity sensing unit 23, so as to reduce measurement errors caused by condensation of moisture on the surface of the humidity-sensitive polymer 232 under a high humidity environment, and improve the accuracy of the device; on the other hand, the dehumidification process can be accelerated, the desorption time can be shortened, and the hysteresis effect of moisture absorption and dehumidification of the sensor can be reduced. According to the embodiment of the present application, the specific position of the heating structure 221 may be changed according to the production requirement, and may be located below the humidity sensing unit 23 (e.g., below the insulating layer 222) or at the same layer as the interdigital electrode 231 structure.
As shown in fig. 2, the humidity sensor chip 10a may further include a conductive via 21 penetrating the substrate, which is opened on the first surface 201 of the substrate and coupled to the CMOS integrated circuit unit 22. According to one embodiment, the conductive via 21 may be filled with a conductive material 211 and an insulating layer 212 (e.g., silicon oxide) disposed between the conductive via 21 sidewall and the conductive material 211. One end of the conductive material 211 is electrically connected to the CMOS integrated circuit unit 22.
According to an embodiment, the humidity sensor chip 10a may further include a mask layer 224 located below the second surface 202, and the mask layer 224 may cover the second surface 202 for protecting the chip, and an opening is located below the conductive through hole 21 after patterning, so as to electrically connect the conductive material 211 with an external circuit.
According to an embodiment, the humidity sensor chip 10a may further include a patterned metal conductive layer 225 located under the mask layer 224 and electrically connected to the conductive material 211 in the conductive via 21.
According to one embodiment, the humidity sensor chip 10a may further include a passivation layer 226 under the metal conductive layer 225, the passivation layer 226 being provided with an opening under the metal conductive layer 225. According to one embodiment, the alternative humidity sensor chip 10a may further include metal balls 227 formed in the openings of the passivation layer 226 in electrical connection with the metal conductive layer 225, the metal balls 227 being available for electrical connection with an external circuit. According to one embodiment, the metal conductive layer 225 or the metal ball 227 may serve as an extraction electrode of the humidity sensor chip 10 a.
According to one embodiment, when the humidity in the air contacting the humidity-sensing polymer 232 changes, the humidity-sensing polymer 232 absorbs the humidity in the air, causing the dielectric constant of the humidity-sensing polymer 232 to change, thereby causing the capacitance between the interdigital electrodes 231 to change. The capacitance change value is transmitted to the CMOS integrated circuit unit 22 electrically connected to the interdigital electrode 231, and the CMOS integrated circuit unit 22 converts the capacitance change value into an electric signal, which is transmitted to an external circuit through the conductive via 21 and the metal ball 227.
FIG. 4 is a cross-sectional schematic view of a housing in a MEMS capacitive humidity sensor with wafer level packaging according to one embodiment of the present application. As shown in fig. 4, the housing 10b includes a substrate 401, and the substrate 401 is provided with a cavity 402. The projected position of the cavity 402 covers the humidity sensing unit 23.
According to one embodiment of the present application, cavity 402 is located inside the substrate, partially or completely surrounded by substrate 401.
According to one embodiment of the present application, the material of the substrate 401 of the housing 10b may include silicon.
As shown in fig. 4, the case 10b further includes an insulating layer 403 over the substrate 401. The insulating layer 403 is provided with a through hole 404 penetrating the housing 10b at a portion above the cavity 402, and the through hole 404 may expose the moisture-sensitive polymer 232 so that external moisture is in contact with the moisture-sensitive polymer 232.
According to one embodiment of the present application, the material of the insulating layer 403 includes silicon oxide.
According to another embodiment of the present application, the through holes 404 may include one or more through holes penetrating the upper surface of the housing 10b, and the number of the through holes and the area of each through hole may be determined according to actual needs.
According to an embodiment of the present application, the sum of the areas of the projections of the through holes 404 on the humidity sensor chip 10a is not smaller than the surface area of the humidity sensing unit 23 in the humidity sensor chip 10 a.
According to another embodiment of the present application, the sum of the projected areas of the through holes 404 on the humidity sensor chip 10a is not less than 50% of the surface area of the humidity sensing unit 23 in the humidity sensor chip 10 a.
According to one embodiment, the through holes 404 may be circular or square, and may be determined according to actual needs.
According to an embodiment, the housing 10b may further include a second encapsulation ring 41 for bonding to complete bonding with the first encapsulation ring 24 of the humidity sensor chip 10 a. By adopting the scheme, the occupied space of the integrated capacitive humidity sensor chip can be greatly saved, the volume of the humidity sensor is reduced, and the influence of a routing process connecting circuit on the chip is reduced. In addition, the integrated capacitive humidity sensor chip design that this application adopted can also protect humidity sensing unit, keeps apart humidity-sensitive medium and circuit when integrated sensor and circuit, ensures the device performance, improves capacitive humidity sensor's the degree of accuracy.
The above-described embodiments are provided for illustrative purposes only and are not intended to be limiting, and various changes and modifications may be made by those skilled in the art without departing from the scope of the present disclosure, and therefore, all equivalent technical solutions should fall within the scope of the present disclosure.
Claims (11)
1. A MEMS capacitive humidity sensor with wafer level packaging, comprising:
a humidity sensor chip including a humidity sensing unit on an upper surface of the chip;
the shell comprises an upper surface and a cavity below the upper surface, the lower surface of the shell is bonded with the first packaging ring on the upper surface of the chip through a second packaging ring, and therefore a cavity is formed between the shell and the chip and at least contains the humidity sensing unit; and
the shell also comprises one or more through holes penetrating through the upper surface of the shell, and the projection of the through holes on the upper surface of the chip is positioned in the range of the humidity sensing unit.
2. The MEMS capacitive humidity sensor with wafer level packaging of claim 1 wherein
The chip comprises a first substrate and an integrated circuit unit, wherein one end of the integrated circuit unit is electrically connected with the humidity sensing unit, and the other end of the integrated circuit unit is electrically connected with an external circuit through a conductive material in a conductive through hole penetrating through the first substrate.
3. The MEMS capacitive humidity sensor with wafer level packaging of claim 2 wherein
The chip includes a heating structure located below the humidity sensing unit.
4. The MEMS capacitive humidity sensor with wafer level packaging of claim 2 wherein
The chip comprises a heating structure, and the heating structure and the humidity sensing unit are located on the same layer.
5. The MEMS capacitive humidity sensor with wafer level packaging of claim 1 wherein
The humidity sensing unit comprises a humidity sensing polymer and interdigital electrodes, wherein the interdigital electrodes are located on the upper surface of the chip, and the humidity sensing polymer covers the interdigital electrodes.
6. The MEMS capacitive humidity sensor with wafer level packaging of claim 5, wherein
The humidity sensing unit further comprises a passivation layer, wherein the passivation layer is located between the humidity sensing polymer and the interdigital electrodes and covers the interdigital electrodes.
7. The MEMS capacitive humidity sensor with wafer level packaging of claim 6, wherein
The structure of the interdigital electrode comprises a single pair of interdigital structures or a differential interdigital structure.
8. The MEMS capacitive humidity sensor with wafer level packaging of claim 1 wherein
The shell comprises a second substrate and an insulating layer, wherein the insulating layer is positioned above the second substrate and forms the upper surface of the shell, and the insulating layer is arranged on the second substrate and forms the upper surface of the shell
The cavity is formed in the second substrate, and the through hole penetrates through the insulating layer.
9. The MEMS capacitive humidity sensor with wafer level packaging of claim 1 wherein
The sum of the areas of the one or more through holes is not less than 50% of the surface area of the humidity sensing unit.
10. The MEMS capacitive humidity sensor with wafer level packaging of claim 8, wherein
A part or all of the cavity is surrounded by the second substrate.
11. The MEMS capacitive humidity sensor with wafer level packaging of claim 8 wherein said second substrate is a silicon substrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220308458.3U CN217133024U (en) | 2022-02-16 | 2022-02-16 | MEMS capacitive humidity sensor with wafer level packaging |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220308458.3U CN217133024U (en) | 2022-02-16 | 2022-02-16 | MEMS capacitive humidity sensor with wafer level packaging |
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| CN217133024U true CN217133024U (en) | 2022-08-05 |
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| CN202220308458.3U Active CN217133024U (en) | 2022-02-16 | 2022-02-16 | MEMS capacitive humidity sensor with wafer level packaging |
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