CN117819469A - Inertial sensor and preparation method thereof, and electronic device - Google Patents

Abstract

The present disclosure provides an inertial sensor and a preparation method thereof, and an electronic device, belonging to the technical field of inertial micro-electromechanical systems, wherein the inertial sensor is divided into at least one device unit, the device unit having a functional area and a bonding area surrounding the functional area; the inertial sensor comprises a dielectric substrate, a cover plate, and a device layer arranged between the dielectric substrate and the cover plate; the dielectric substrate has a first surface and a second surface arranged oppositely along a thickness direction thereof; the cover plate has a third surface and a fourth surface arranged oppositely along a thickness direction thereof; the second surface and the third surface are arranged oppositely; the dielectric substrate has a first groove running through a part of its thickness, and a first opening of the first groove is located on the first surface; the cover plate has a second groove running through a part of its thickness, and a second opening of the second groove is located on the fourth surface; the first groove and the second groove are both located in the bonding area.

Description

Inertial sensor and preparation method thereof, and electronic device

Technical Field

The present disclosure belongs to the technical field of inertial micro-electromechanical systems, and in particular relates to an inertial sensor and a preparation method thereof, and an electronic device.

Background technique

Inertial sensors are a type of inertial instrument and the inertial measurement device and inertial measurement system that use inertial instruments. Inertial sensors include, for example, accelerometers, gyroscopes, and inertial measurement units (IMUs) composed of accelerometers and gyroscopes. The six-axis IMU is the mainstream development direction of inertial devices in micro-electro-mechanical systems (MEMS). Its core is to integrate accelerometers and gyroscopes on a single wafer and perform wafer-level bonding and packaging. During the bonding process, the device layer is susceptible to compressive stress, causing the wafer to warp.

Summary of the invention

The present disclosure aims to solve at least one of the technical problems existing in the prior art and provides an inertial sensor and a preparation method thereof, and an electronic device.

In a first aspect, the technical solution adopted to solve the technical problem of the present disclosure is an inertial sensor, which is divided into at least one device unit, wherein the device unit has a functional area and a bonding area surrounding the functional area; the inertial sensor comprises a dielectric substrate, a cover plate, and a device layer arranged between the dielectric substrate and the cover plate;

The dielectric substrate has a first surface and a second surface arranged opposite to each other along its thickness direction; the cover has a third surface and a fourth surface arranged opposite to each other along its thickness direction; the second surface and the third surface are arranged opposite to each other;

The dielectric substrate has a first groove that runs through part of its thickness, and a first opening of the first groove is located on the first surface; the cover plate has a second groove that runs through part of its thickness, and a second opening of the second groove is located on the fourth surface; the first groove and the second groove are both located in the bonding area.

In some embodiments, the material of the cover plate and/or the material of the dielectric substrate is borosilicate glass.

In some embodiments, the dielectric substrate includes a first chamber groove extending through a portion of its thickness, and a third opening of the first chamber groove is located on the second surface; the cover plate includes a second chamber groove extending through a portion of its thickness, and a fourth opening of the second chamber groove is located on the third surface; the first chamber groove and the second chamber groove are both located in the functional area.

In some embodiments, the device layer includes an inertial device; the first chamber groove and the second chamber groove are arranged opposite to each other to form a accommodating chamber; the accommodating chamber is located in the functional area; and the inertial device is confined in the accommodating chamber.

In some embodiments, the inertial sensor further includes a getter film; the getter film is disposed in the second chamber groove and attached to the groove bottom of the second chamber groove.

In some embodiments, the inertial sensor further includes a bottom electrode; the bottom electrode is disposed in the first chamber groove, attached to the bottom of the first chamber groove, and extends from one end to the bonding area.

In some embodiments, the first groove and/or the second groove is an annular groove surrounding the functional area.

In some embodiments, the cover plate has a plurality of through holes penetrating along a thickness direction thereof; the through holes are located in the bonding area and are closer to the functional area than the second groove.

In some embodiments, a conductive layer is disposed on the inner wall of the through hole.

In some embodiments, the ratio between the thickness of the dielectric substrate and the depth of the first groove is between 50 and 100; and/or,

The ratio between the thickness of the cover plate and the depth of the second groove is between 50 and 100.

In some embodiments, a contour shape of at least one of the first groove and the second groove includes a quadrilateral, a hexagon, or an octagon.

In some embodiments, the depth and width of the first groove are the same; the depth and width of the second groove are the same.

In a second aspect, the present disclosure also provides a method for preparing an inertial sensor, which includes:

Providing a dielectric substrate raw material and a cover plate raw material;

A first groove is formed on the dielectric substrate raw material to obtain a dielectric substrate; the dielectric substrate has a first surface and a second surface arranged opposite to each other along a thickness direction thereof; a first opening of the first groove is located on the first surface;

A second groove is formed on the cover plate raw material to obtain a cover plate; the cover plate has a third surface and a fourth surface which are arranged opposite to each other along the thickness direction thereof; and the second opening of the second groove is located on the fourth surface;

A device layer is formed on the second surface of the dielectric substrate, and the cover is formed on a side of the device layer away from the dielectric substrate to obtain an inertial sensor; the inertial sensor includes at least one device unit; the device unit has a functional area and a bonding area surrounding the functional area; the first groove and the second groove are both located in the bonding area.

In some embodiments, after forming the second groove on the cover plate raw material, forming the cover plate includes:

On the cover plate material forming the second groove, a through hole penetrating the cover plate material is formed along the thickness direction of the cover plate material to obtain a cover plate.

In some embodiments, the inertial sensor includes a getter film;

After forming the second groove on the cover plate raw material, the method further includes:

On the cover plate material forming the second groove, a getter film is formed in the second groove; the getter film is attached to the groove bottom of the second chamber groove.

In a third aspect, an embodiment of the present disclosure further provides an electronic device, which includes an inertial sensor as described in any one of the above embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of an inertial sensor provided by an embodiment of the present disclosure;

FIG2 is a schematic diagram of a specific structure of a chamber groove in an inertial sensor provided by an embodiment of the present disclosure;

FIG3a is a schematic diagram of a specific structure of an inertial sensor provided in an embodiment of the present disclosure;

FIG3 b is a schematic diagram of the three-dimensional structure of an inertial sensor provided in an embodiment of the present disclosure;

FIG4a is a schematic diagram of the spatial structure of a cover plate provided in an embodiment of the present disclosure;

FIG4b is a schematic diagram of a cover plate from a fourth surface perspective provided by an embodiment of the present disclosure;

FIG4c is a schematic diagram of a cover plate from a third surface perspective provided by an embodiment of the present disclosure;

FIG5a is a schematic diagram of the spatial structure of a dielectric substrate provided by an embodiment of the present disclosure;

FIG5 b is a schematic diagram of a dielectric substrate provided by an embodiment of the present disclosure from a first surface perspective;

FIG5c is a schematic diagram of a dielectric substrate from a second surface perspective provided by an embodiment of the present disclosure;

FIG6 is a schematic diagram of an exemplary first groove provided in an embodiment of the present disclosure;

7a to 7i are schematic flow charts of a method for preparing an inertial sensor provided in an embodiment of the present disclosure.

The reference numerals are as follows: inertial sensor 100; device unit 10; functional area AA; bonding area BB; dielectric substrate 11; cover plate 12; device layer 13; first surface 11a; second surface 11b; third surface 12a; fourth surface 12b; first groove 111; first chamber groove 112; second groove 121; second chamber groove 122; accommodating chamber 20; inertial device 131; accelerometer 131a; gyroscope 131b; getter film 14; bottom electrode 15; first sub-groove 111a; through hole 123; conductive layer 16; wire bonding layer 17; device preparation layer 30.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure for protection, but merely represents the selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present disclosure.

Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate quantity restrictions, but indicate that there is at least one. Similar words such as "include" or "comprise" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

The "multiple or several" mentioned in this disclosure refers to two or more. "And/or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character "/" generally indicates that the associated objects before and after are in an "or" relationship.

In the relevant technology, the six-axis IMU is the mainstream development direction of inertial devices in MEMS. The core of its production is to integrate the accelerometer and gyroscope on a single wafer and perform wafer-level bonding packaging. During the bonding process, the device layer is susceptible to compressive stress, causing the wafer to warp. In traditional technology, in order to prevent the wafer from warping, the bonding layer material used in the bonding process of the inertial sensor is usually the precious metal gold (Au), and the use of precious metals in the bonding process greatly increases the production cost of the inertial sensor. In addition, in order to improve insulation and reduce the influence of parasitic capacitance on device signals, in the process of preparing inertial sensors, a PN junction is usually made under the bottom electrode of the inertial sensor or high-resistance silicon is used as a dielectric substrate, which increases the difficulty of the inertial sensor preparation process and further increases the production cost of the inertial sensor.

Based on this, the present disclosure particularly provides an inertial sensor 100 which substantially eliminates one or more of the problems caused by the limitations and defects of the related art. FIG1 is a schematic diagram of an inertial sensor provided by an embodiment of the present disclosure. As shown in FIG1 , specifically, an inertial sensor 100 is divided into at least one device unit 10, and the device unit 10 has a functional area AA and a bonding area BB surrounding the functional area AA; the inertial sensor 100 includes a dielectric substrate 11, a cover plate 12, and a device layer 13 arranged between the dielectric substrate 11 and the cover plate 12; the dielectric substrate 11 has a first surface 11a and a second surface 11b arranged oppositely along a thickness direction Z thereof; the cover plate 12 has a third surface 12a and a fourth surface 12b arranged oppositely along a thickness direction Z thereof; the second surface 11b and the third surface 12a are arranged oppositely; the dielectric substrate 11 has a first groove 111 running through a portion of its thickness, and a first opening of the first groove 111 is located on the first surface 11a; the cover plate 12 has a second groove 121 running through a portion of its thickness, and a second opening of the second groove 121 is located on the fourth surface 12b; the first groove 111 and the second groove 121 are both located in the bonding area BB.

The embodiment of the present disclosure provides a first groove 111 in the bonding area BB of the dielectric substrate 11, so as to release the compressive stress on the device layer 13 when the dielectric substrate 11 is bonded to the device layer 13, prevent the device layer 13 from warping, and ensure the flatness of the device layer 13 after bonding. Similarly, the second groove 121 is provided in the bonding area BB on the cover plate 12, so as to release the compressive stress on the device layer 13 when the cover plate 12 is bonded to the device layer 13, prevent the device layer 13 from warping, and ensure the flatness of the device layer 13 after bonding. The embodiment of the present disclosure improves the inherent structure of the inertial sensor 100, that is, improves the dielectric substrate 11 and the cover plate 12 existing in the inertial sensor 100 itself, and can release the compressive stress on the device layer 13 without preparing precious metal bonding separately, thereby reducing the manufacturing cost of the inertial sensor 100 and simplifying the difficulty of the manufacturing process of the inertial sensor 100.

The specific structure of an inertial sensor 100 provided in an embodiment of the present disclosure is introduced in detail below. As shown in FIG. 1 , the inertial sensor 100 is divided into at least one device unit 10. The device unit 10 has a functional area AA and a bonding area BB surrounding the functional area AA. The inertial sensor 100 includes a dielectric substrate 11, a cover plate 12, and a device layer 13 disposed between the dielectric substrate 11 and the cover plate 12.

The inertial sensor 100 in the embodiment of the present disclosure may be a six-axis inertial sensor. The embodiment of the present disclosure is described by taking a six-axis inertial sensor as an example. Of course, the inertial sensor in the embodiment of the present disclosure may also be a two-axis inertial sensor, a three-axis inertial sensor, a four-axis inertial sensor, etc., and a reasonable structural design may be made according to the requirements of the application scenario, and the embodiment of the present disclosure does not specifically limit it.

The device layer 13 includes an inertial device 131 of the inertial sensor 100 (see FIG. 2 or FIG. 3a below for details), and the inertial device 131 includes, for example, an accelerometer 131a, a gyroscope 131b, etc. The functional area AA of the device unit 10 is used to set the inertial device 131. The bonding area BB of the device unit 10 is used for bonding between the film layers of the inertial sensor 100, such as bonding between the dielectric substrate 11 and the device layer 13, and bonding between the cover plate 12 and the device layer 13.

The number of device units 10 is related to the number of inertial devices 131 in the inertial sensor 100. The inertial device 131 includes, for example, an accelerometer 131a, a gyroscope 131b, etc. The inertial sensor 100 is at least one of the accelerometer 131a and the gyroscope 131b, or a combination of the two. Exemplarily, if the inertial device 131 in the inertial sensor 100 includes the accelerometer 131a and the gyroscope 131b, the inertial sensor 100 is divided into two parallel device units 10, one of which includes the accelerometer 131a and is located in the functional area AA of the device unit 10, and the other device unit 10 includes the gyroscope 131b and is located in the functional area AA of the device unit 10. As another example, if the inertial device 131 in the inertial sensor 100 includes only the accelerometer 131a (or only the gyroscope 131b), the inertial sensor 100 is the device unit 10, and the functional area AA in the inertial sensor 100 is provided with the accelerometer 131a (or the gyroscope 131b).

As shown in FIG1 , the dielectric substrate 11 has a first surface 11a and a second surface 11b that are oppositely arranged along the thickness direction Z thereof; the cover plate 12 has a third surface 12a and a fourth surface 12b that are oppositely arranged along the thickness direction Z thereof; the second surface 11b and the third surface 12a are oppositely arranged. The dielectric substrate 11 has a first groove 111 that runs through part of its thickness, and the first opening of the first groove 111 is located on the first surface 11a; the cover plate 12 has a second groove 121 that runs through part of its thickness, and the second opening of the second groove 121 is located on the fourth surface 12b; the first groove 111 and the second groove 121 are both located in the bonding area BB.

Here, the first surface 11a and the fourth surface 12b are both outer surfaces of the inertial sensor 100, wherein the first surface 11a is the bottom surface of the inertial sensor 100, and the fourth surface 12b is the top surface of the inertial sensor 100. The first groove 111 is located in the bonding area BB of the bottom surface. When the dielectric substrate 11 is bonded to the device layer 13, the compressive stress on the device layer 13 can be released through the first groove 111 located in the bonding area BB, thereby reducing the device warpage caused by the compressive stress and the risk of the device layer 13 being cracked. The second groove 121 is located in the bonding area BB of the top surface. When the cover plate 12 is bonded to the device layer 13, the compressive stress on the device layer 13 can be released through the second groove 121 located in the bonding area BB, thereby reducing the device warpage caused by the compressive stress and the risk of the device layer 13 being cracked.

In some embodiments, the material of the cover plate 12 and/or the material of the dielectric substrate 11 is borosilicate glass. Borosilicate glass is known to be a material with high resistance and low dielectric loss. Therefore, the material of the dielectric substrate 11 selected in the embodiment of the present disclosure is borosilicate glass, which has low dielectric loss and high resistivity characteristics compared to the silicon dielectric substrate 11, and can effectively reduce the influence of the parasitic capacitance formed in the device structure on the signal of the inertial sensor 100. The material of the cover plate 12 selected in the embodiment of the present disclosure is borosilicate glass, which can ensure that the device structure forms a smaller parasitic capacitance. In addition, the use of borosilicate glass as a bonding material reduces the cost of the bonding material; the difficulty of the preparation process of the glass cover plate and the glass dielectric substrate is less than that of the preparation process of the high-resistance silicon dielectric substrate, which can further reduce the production cost of the inertial sensor 100.

In some embodiments, Figure 2 is a schematic diagram of the specific structure of the chamber groove in the inertial sensor provided in the embodiment of the present disclosure. As shown in Figure 2, the dielectric substrate 11 includes a first chamber groove 112 that runs through part of its thickness, and the third opening of the first chamber groove 112 is located on the second surface 11b; the cover plate 12 includes a second chamber groove 122 that runs through part of its thickness, and the fourth opening of the second chamber groove 122 is located on the third surface 12a; the first chamber groove 112 and the second chamber groove 122 are both located in the functional area AA.

The first chamber groove 112 and the second chamber groove 122 are both located in the functional area AA, and can provide movable space for the inertial device 131 in the inertial sensor 100 .

The depth of the first chamber groove 112 can be determined based on the structure to be accommodated and the spatial range in which the inertial device 131 can move. For example, the first chamber groove 112 is used to accommodate the bottom electrode 15 of the inertial sensor 100. The depth of the first chamber groove 112 can be determined based on the thickness of the bottom electrode 15. Specifically, the depth of the first chamber groove 112 is greater than the thickness of the bottom electrode 15. Except for the space occupied by the bottom electrode 15 in the first chamber groove 112, the remaining available space can be used for the activity space of the inertial device 131 in the device layer 13. Similarly, the depth of the second chamber groove 122 can be determined based on the structure to be accommodated and the spatial range in which the inertial device 131 can move. For example, the second chamber groove 122 is used to accommodate the getter film 14 of the inertial sensor 100. The depth of the second chamber groove 122 can be determined based on the thickness of the getter film 14. Specifically, the depth of the second chamber groove 122 is greater than the thickness of the getter film 14. Except for the space occupied by the bottom electrode 15 in the first chamber groove 112, the remaining available space can be used for the activity space of the inertial device 131 in the device layer 13.

FIG3a is a schematic diagram of the specific structure of the inertial sensor provided in an embodiment of the present disclosure, and FIG3b is a schematic diagram of the three-dimensional structure of the inertial sensor provided in an embodiment of the present disclosure. FIG4a is a schematic diagram of the spatial structure of the cover provided in an embodiment of the present disclosure, and FIG4b is a schematic diagram of the cover provided in an embodiment of the present disclosure from the fourth surface as the perspective, and FIG4c is a schematic diagram of the cover provided in an embodiment of the present disclosure from the third surface as the perspective. FIG5a is a schematic diagram of the spatial structure of the dielectric substrate provided in an embodiment of the present disclosure, and FIG5b is a schematic diagram of the dielectric substrate provided in an embodiment of the present disclosure from the first surface as the perspective, and FIG5c is a schematic diagram of the dielectric substrate provided in an embodiment of the present disclosure from the second surface as the perspective.

In some embodiments, as shown in FIG. 3 a , the device layer 13 includes an inertial device 131 ; the first chamber groove 112 and the second chamber groove 122 are arranged opposite to each other to form a receiving chamber 20 ; the receiving chamber 20 is located in the functional area AA; and the inertial device 131 is confined within the receiving chamber 20 .

Optionally, the first chamber groove 112 and the second chamber groove 122 have the same shape and size, and the first chamber groove 112 and the second chamber groove 122 are arranged relative to each other to form a regular accommodating space in the functional area AA, that is, the accommodating chamber 20, which can confine the inertial device 131 in the device layer 13 within the accommodating chamber 20.

In some embodiments, during the bonding process of the inertial sensor 100, the first chamber groove 112 and the second chamber groove 122 are easily affected by high temperature and high pressure, which may damage the bonding. In addition, the high air pressure in the receiving chamber 20 may also affect the inertial device 131 in the movable receiving chamber 20. Therefore, it is necessary to ensure the low pressure in the internal space of the receiving chamber 20.

As shown in FIG. 3 a and FIG. 4 a to FIG. 4 c , the inertial sensor 100 further includes a getter film 14 ; the getter film 14 is disposed in the second chamber groove 122 and attached to the bottom of the second chamber groove 122 to ensure low pressure in the accommodating chamber 20 in the inertial sensor 100 .

Alternatively, the material of the getter film 14 may be titanium (Ti).

In some embodiments, as shown in FIG. 3a and FIG. 5a to FIG. 5c, the inertial sensor 100 further includes a bottom electrode 15; the bottom electrode 15 is disposed in the first chamber groove 112, and is attached to the bottom of the first chamber groove 112, and extends from one end to the bonding area BB. One end of the bottom electrode 15 extends from the first chamber groove 112 in the functional area AA to the second surface 11b of the dielectric substrate 11 in the bonding area BB, and the portion of the bottom electrode 15 extending to the second surface 11b of the dielectric substrate 11 is used for bonding with the device layer 13. The bonding method may be, for example, but not limited to, welding.

For example, the material of the bottom electrode 15 may include but is not limited to titanium (Ti) and copper (Cu).

In some embodiments, as shown in FIG. 3 b , FIG. 4 a and FIG. 4 b , the first groove 111 and/or the second groove 121 is an annular groove surrounding the functional area AA.

Here, for a device unit 10, the annular groove surrounds the entire functional area AA, the bonding area BB also surrounds the entire functional area AA, and the first groove 111 and the second groove 121 are located in the bonding area BB. Therefore, when the membrane layer structure (that is, the dielectric substrate 11, the cover plate 12 and the device layer 13) in the inertial sensor 100 is bonded, the annular groove surrounding the entire functional area AA can fully release the compressive stress on the device layer 13 in the bonding area BB, reduce the warping of the device layer 13 caused by the compressive stress, and reduce the risk of the device layer 13 cracking.

Optionally, the first groove 111 and the second groove 121 have the same shape and size, and the first groove 111 and the second groove 121 opposite to each other can work together to release the compressive stress on the device layer 13 in the bonding area BB, thereby reducing the risk of the device layer 13 cracking.

In some embodiments, FIG6 is a schematic diagram of an exemplary first groove provided in an embodiment of the present disclosure. As shown in FIG6, the first groove 111 includes a plurality of first sub-grooves 111a, each of which is located in the bonding area BB on the dielectric substrate 11, and the first sub-grooves 111a are not connected to each other, and the contour formed by the plurality of first sub-grooves 111a surrounds the functional area AA. Similar to the structure shown in FIG6, the second groove 121 includes a plurality of second sub-grooves, each of which is located in the bonding area BB on the cover plate 12, and the second sub-grooves are not connected to each other, and the contour formed by the plurality of second sub-grooves surrounds the functional area AA.

Here, while the stress is released by the first groove 111 and the second groove 121 , the mechanical strength of the dielectric substrate 11 and the cover plate 12 can be ensured.

Of course, under the condition that the first groove 111 and the second groove 121 can release stress, the contours of the first groove 111 and the second groove 121 can also be set to other shapes, which is not specifically limited in the embodiments of the present disclosure.

Optionally, the contour shape of the first groove 111 and/or the second groove 121 may include but is not limited to a quadrilateral, a hexagon or an octagon. For example, the contour shape of the first groove 111 and/or the second groove 121 may include but is not limited to a rounded quadrilateral or a rounded octagon. The side length of the quadrilateral is greater than the side length of the accommodating chamber 20.

In some embodiments, the ratio of the thickness of the dielectric substrate 11 to the depth of the first groove 111 is between 50 and 100; and/or the ratio of the thickness of the cover plate 12 to the depth of the second groove 121 is between 50 and 100.

Exemplarily, the depth of the first groove 111 is between 5 μm and 8 μm, and the depth of the second groove 121 is between 5 μm and 8 μm. The thickness of the dielectric substrate 11 is between 400 μm and 500 μm.

In some embodiments, the depth and width of the first groove 111 are the same; the depth and width of the second groove 121 are the same.

In some embodiments, the material of the device layer 13 is low-resistance single crystal silicon. The device layer 13 includes an inertial device 131 , a beam for connecting the inertial device 131 with other structures, and parallel plates, etc. The parallel plates are used to conduct electrical signals of the inertial device 131 .

Exemplarily, the thickness of the device layer 13 is between 20 μm and 60 μm.

In some embodiments, as shown in FIG. 3 a and FIG. 4 a to FIG. 4 c , the cover plate 12 has a plurality of through holes 123 penetrating along the thickness direction Z thereof; the through holes 123 are located in the bonding area BB and are closer to the functional area AA than the second groove 121 .

Here, the through hole 123 is located in the bonding area BB, and different through holes 123 correspond to different electrical signal lead-out terminals in the device layer 13 . The potentials of the electrical signal lead-out terminals may be different or the same.

In some embodiments, a conductive layer 16 is disposed on the inner wall of the through hole 123. The conductive layer 16 in one through hole 123 is electrically connected to the lead-out terminal of the corresponding electrical signal, so as to lead out the electrical signal of the inertial device 131.

In some embodiments, the ratio between the thickness of the cover plate 12 and the diameter of the through hole 123 is between 5 and 7.

In some embodiments, a wire bonding layer 17 electrically connected to the conductive layer 16 is disposed on the fourth surface 12b of the cover plate 12. The wire bonding layer 17 is used for wire bonding connection with an external chip, and is used for transmitting the electrical signal of the inertial sensor 100 to the external chip, for example, transmitting the electrical signal of the inertial sensor 100 to an application specific integrated circuit (ASIC).

The above content is a detailed introduction to the structure of the inertial sensor 100. The inertial sensor 100 provided by the embodiment of the present disclosure is provided with a first groove 111 in the bonding area BB of the dielectric substrate 11, and a second groove 121 in the bonding area BB of the cover plate 12, which can release the compressive stress on the device layer 13 when the device layer 13 is bonded, prevent the device layer 13 from warping, and ensure the flatness of the device layer 13 after bonding. In addition, using borosilicate glass as a bonding material can reduce the bonding cost and bonding difficulty of the inertial sensor 100.

Based on the inertial sensor 100 provided above, the embodiment of the present disclosure further provides a method for preparing the inertial sensor 100. FIGS. 7a to 7i are schematic flow charts of the method for preparing the inertial sensor provided in the embodiment of the present disclosure, which includes the following steps S11 to S14:

S11, providing a dielectric substrate raw material and a cover plate raw material.

The material of the dielectric substrate raw material is the same as that of the dielectric substrate 11, and the dielectric substrate 11 is formed by structurally designing the dielectric substrate raw material. The material of the cover plate raw material is the same as that of the cover plate 12, and the cover plate 12 is formed by structurally designing the cover plate raw material.

S12, forming a first groove 111 on the dielectric substrate raw material to obtain a dielectric substrate 11; the dielectric substrate 11 has a first surface 11a and a second surface 11b arranged opposite to each other along a thickness direction Z thereof; and a first opening of the first groove 111 is located on the first surface 11a.

As shown in FIG7a, in a specific implementation, laser induced etching can be used to modify the first groove region and the first chamber groove region to be etched of the dielectric substrate original material; then, a wet etching process is used to etch the surface of the dielectric substrate original material in the first groove region to form a first groove 111, and the surface of the dielectric substrate original material in the first chamber groove region to form a first chamber groove 112. Here, the cross-sectional shape of the first groove 111 formed by wet etching is an inverted cone.

The first surface 11 a includes a first groove region, and the second surface 11 b includes a first cavity region.

In some embodiments, the inertial sensor 100 further includes a bottom electrode 15. As shown in FIG7b, after forming the dielectric substrate material of the first groove 111 and the first chamber groove 112, a first sub-electrode attached to the groove bottom of the first groove 111 is formed in the first groove 111 of the dielectric substrate material, and a second sub-electrode extending from the groove bottom of the first groove 111 to the second surface 11b is formed, and the first sub-electrode and the second sub-electrode are an integrated structure, forming the bottom electrode 15. Exemplarily, a metal titanium layer or a metal copper layer can be sputtered in the first groove 111 and at the edge of the second surface 11b adjacent to the first groove 111, and patterned to form the bottom electrode 15.

S13, forming a second groove 121 on the cover plate raw material to obtain the cover plate 12; the cover plate 12 has a third surface 12a and a fourth surface 12b arranged opposite to each other along its thickness direction Z; the second opening of the second groove 121 is located on the fourth surface 12b.

As shown in FIG7c, in a specific implementation, laser induced etching can be used to modify the second groove region and the second chamber groove region of the cover plate original material to be etched; then, a wet etching process is used to etch the surface of the cover plate original material in the second groove region to form a second groove 121, and the surface of the cover plate original material in the second chamber groove region to form a second chamber groove 122. Here, the cross-sectional shape of the second groove 121 formed by wet etching is an inverted cone.

The fourth surface 12b includes a second groove region, and the third surface 12a includes a second cavity region.

In some embodiments, as shown in FIG. 7 d , on the cover plate material having the second groove 121 formed thereon, a through hole 123 penetrating the cover plate material is formed along the thickness direction Z of the cover plate material to obtain the cover plate 12 .

Here, a variety of methods can be used to make through holes 123 in the cover plate raw material. For example: sandblasting, photosensitive glass method, focused discharge method, plasma etching, laser ablation, electrochemical method, laser induced etching, etc. Different methods have different advantages and disadvantages and scope of application. For example, for the sandblasting method, its advantage is that the process is simple, and the aperture of the through hole 123 made by this method is larger, and it is only suitable for the production of through holes 123 with an aperture greater than 200μm. The advantage of the photosensitive glass method is that the process is simple and high-density and high-aspect ratio through holes 123 can be made. The advantage of the focused discharge method is that the hole-forming speed is fast. The side wall roughness of the through hole 123 prepared by the plasma etching method is small. The advantage of the laser ablation method is that it can make high-density and high-aspect ratio through holes 123 with large roughness. The advantages of the electrochemical method are low cost, simple equipment, fast hole-forming rate, and a large diameter of the through hole 123. The advantage of the laser induced etching method is that the hole-forming rate is fast, and high-density, high-aspect-ratio through-holes 123 can be produced, and there is no damage inside the through-holes 123. The disadvantage is that the laser equipment is expensive. Here, laser induced etching is taken as an example, and the through-hole 123 is prepared by the laser induced etching method. First, the position where the through-hole 123 needs to be made is laser-induced modified by laser, and then the through-hole 123 is made by wet etching. Since the through-hole 123 can only be made by single-sided etching, the cover plate 12 is obtained. The ratio between the aperture of the through-hole 123 and the thickness of the cover plate 12 is between 1:5 and 1:7. The through-hole 123 should be kept as vertical as possible to the horizontal plane to reduce the space occupied by the lead.

In some embodiments, the inertial sensor 100 further includes a getter film 14. As shown in FIG. 7e, a conductive layer 16 is formed on the inner wall of the through hole 123; and a getter film 14 attached to the bottom of the second groove 121 is formed in the second groove 121. Exemplarily, the inner wall of the through hole 123 of the cover plate 12 is sputtered and electroplated with a metal titanium layer or a metal copper layer, and the inner wall of the through hole 123 is metalized to form the conductive layer 16. A getter is sputtered on the bottom of the second groove 121 to form the getter film 14.

S14 , forming a device layer 13 on the second surface 11 b of the dielectric substrate 11 , and forming a cover plate 12 on a side of the device layer 13 away from the dielectric substrate 11 , thereby obtaining an inertial sensor 100 .

The inertial sensor 100 includes at least one device unit 10 ; the device unit 10 has a functional area AA and a bonding area BB surrounding the functional area AA; the first groove 111 and the second groove 121 are both located in the bonding area BB.

Specifically, as shown in FIG7f, a low-resistance silicon layer is bonded to the second surface 11b of the dielectric substrate 11, and the low-resistance silicon layer is ground and polished to a thickness of 20 μm to 60 μm to form a device preparation layer 30; then, as shown in FIG7g, a deep reactive ion etching process can be used to etch the device preparation layer 30 to form an inertial device 131 and different potential areas to obtain a device layer 13. Different potential areas correspond to different through holes 123.

Optionally, the material of the dielectric substrate 11 may be borosilicate glass.

Here, the first groove 111 located in the bonding area BB on the dielectric substrate 11 can release the compressive stress on the low-resistance silicon layer of the dielectric substrate 11 when bonding, prevent the low-resistance silicon layer from warping, and ensure the flatness of the device layer 13 after bonding. In addition, the material of the dielectric substrate 11 is borosilicate glass, which has low dielectric loss and high resistivity characteristics compared to the silicon dielectric substrate 11, and can effectively reduce the influence of the parasitic capacitance formed in the device structure on the signal of the inertial sensor 100. Using borosilicate glass as a bonding material reduces the cost of the bonding material; the difficulty of the preparation process of the glass dielectric substrate 11 is less than that of the high-resistance silicon dielectric substrate 11, which can further reduce the production cost of the inertial sensor 100.

As shown in FIG7h, the bonding cover plate 12 is bonded to the device layer 13, specifically, the third surface 12a of the cover plate 12 is bonded to the surface of the device layer 13 facing away from the dielectric substrate 11; as shown in FIG7i, a metal titanium layer or a metal copper layer is sputtered on the metal interconnection area of the fourth surface 12b of the cover plate 12 to form a wire bonding layer 17, thereby obtaining the inertial sensor 100.

Optionally, the cover plate 12 may be made of borosilicate glass.

Here, the second groove 121 on the cover plate 12 located in the bonding area BB can release the compressive stress on the device layer 13 when the cover plate 12 is bonded to the device layer 13, prevent the device layer 13 from warping, and ensure the flatness of the device layer 13 after bonding. In addition, the material of the cover plate 12 is borosilicate glass, which has low dielectric loss and high resistivity characteristics compared to the silicon dielectric substrate 11, and can effectively reduce the influence of the parasitic capacitance formed in the device structure on the inertial sensor 100 signal. Using borosilicate glass as a bonding material reduces the cost of the bonding material; the difficulty of the preparation process of the glass cover plate 12 is less than that of the preparation process of the high-resistance silicon cover plate 12, which can further reduce the production cost of the inertial sensor 100.

The embodiment of the present disclosure further provides an electronic device, which includes the inertial sensor 100 as described in any one of the above embodiments.

The inertial sensor 100 provided in the embodiment of the present disclosure is mainly used to detect and measure acceleration, tilt, impact, vibration, rotation and multi-degree of freedom (DOF) motion for navigation, orientation and motion carrier control.

The inertial sensor 100 can be applied to consumer electronic products, and the electronic devices including the inertial sensor 100 can be, for example, mobile phones, global positioning system (GPS) navigation, game consoles, digital cameras, music players, wireless mice, hard disk protectors, smart toys, pedometers, anti-theft systems, etc. The inertial sensor 100 can also be applied to industrial and automotive products, and the electronic devices including the inertial sensor 100 can be, for example, vehicle posture measurement, industrial automation equipment, large medical equipment, robots, instruments, engineering machinery equipment, etc.

It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims (16)

1. An inertial sensor, which is divided into at least one device unit, wherein the device unit has a functional area and a bonding area surrounding the functional area; the inertial sensor comprises a dielectric substrate, a cover plate, and a device layer disposed between the dielectric substrate and the cover plate; The dielectric substrate has a first surface and a second surface disposed opposite to each other along its thickness direction; the cover plate has a third surface and a fourth surface disposed opposite to each other along its thickness direction; the second surface and the third surface are disposed opposite to each other; The dielectric substrate has a first groove that runs through part of its thickness, and a first opening of the first groove is located on the first surface; the cover plate has a second groove that runs through part of its thickness, and a second opening of the second groove is located on the fourth surface; the first groove and the second groove are both located in the bonding area. 2 . The inertial sensor according to claim 1 , wherein the material of the cover plate and/or the material of the dielectric substrate is borosilicate glass. 3. The inertial sensor according to claim 1, wherein the dielectric substrate includes a first chamber groove that runs through a portion of its thickness, and a third opening of the first chamber groove is located on the second surface; the cover plate includes a second chamber groove that runs through a portion of its thickness, and a fourth opening of the second chamber groove is located on the third surface; and the first chamber groove and the second chamber groove are both located in the functional area. 4. The inertial sensor according to claim 3, wherein the device layer includes an inertial device; the first chamber groove and the second chamber groove are arranged opposite to each other to form a accommodating chamber; the accommodating chamber is located in the functional area; and the inertial device is confined in the accommodating chamber. 5 . The inertial sensor according to claim 3 , wherein the inertial sensor further comprises a getter film; the getter film is disposed in the second cavity groove and attached to the groove bottom of the second cavity groove. 6 . The inertial sensor according to claim 3 , wherein the inertial sensor further comprises a bottom electrode; the bottom electrode is disposed in the first chamber groove, attached to the bottom of the first chamber groove, and extends from one end to the bonding area. 7 . The inertial sensor according to claim 1 , wherein the first groove and/or the second groove is an annular groove surrounding the functional area. 8 . The inertial sensor according to claim 1 , wherein the cover plate has a plurality of through holes penetrating along a thickness direction thereof; the through holes are located in the bonding area and are closer to the functional area than the second groove. 9 . The inertial sensor according to claim 8 , wherein a conductive layer is disposed on an inner wall of the through hole. 10. The inertial sensor according to any one of claims 1 to 7, wherein a ratio between a thickness of the dielectric substrate and a depth of the first groove is between 50 and 100; and/or, The ratio between the thickness of the cover plate and the depth of the second groove is between 50 and 100. 11 . The inertial sensor according to claim 1 , wherein an outline shape of at least one of the first groove and the second groove includes a quadrangle, a hexagon, or an octagon. 12 . The inertial sensor according to claim 1 , wherein the depth and width of the first groove are the same; and the depth and width of the second groove are the same. 13. A method for preparing an inertial sensor, comprising: Providing a dielectric substrate raw material and a cover plate raw material; A first groove is formed on the dielectric substrate raw material to obtain a dielectric substrate; the dielectric substrate has a first surface and a second surface arranged opposite to each other along a thickness direction thereof; a first opening of the first groove is located on the first surface; A second groove is formed on the cover plate raw material to obtain a cover plate; the cover plate has a third surface and a fourth surface which are arranged opposite to each other along the thickness direction thereof; and the second opening of the second groove is located on the fourth surface; A device layer is formed on the second surface of the dielectric substrate, and the cover is formed on a side of the device layer away from the dielectric substrate to obtain an inertial sensor; the inertial sensor includes at least one device unit; the device unit has a functional area and a bonding area surrounding the functional area; the first groove and the second groove are both located in the bonding area. 14. The method for manufacturing an inertial sensor according to claim 13, wherein after forming the second groove on the cover plate raw material, forming the cover plate comprises: On the cover plate material forming the second groove, a through hole penetrating the cover plate material is formed along the thickness direction of the cover plate material to obtain a cover plate. 15. The method for preparing an inertial sensor according to claim 13, wherein the inertial sensor comprises a getter film; After forming the second groove on the cover plate raw material, the method further includes: On the cover plate material forming the second groove, a getter film is formed in the second groove; the getter film is attached to the groove bottom of the second chamber groove. 16. An electronic device comprising the inertial sensor according to any one of claims 1 to 12.