Composite sensor and method for manufacturing the same

Abstract

A composite sensor includes a pressure sensor (10), an accelerometer structure layer (20), and an encapsulation layer (30) stacked together. The accelerometer structure layer (20) includes a substrate (21) and a first cavity (22) disposed on the substrate (21), the first cavity (22) penetrating the substrate (21) in a direction perpendicular to the plane of the composite sensor. The accelerometer structure layer (20) also includes a suspended structure (23), multiple connecting beams (24), and multiple electrical bridges (25). The composite sensor comprises at least one of a first Wheatstone bridge, a second Wheatstone bridge, and a third Wheatstone bridge; a suspended structure (23) is located within a first cavity (22), and multiple connecting beams (24) are arranged around the suspended structure (23), and the suspended structure (23) is connected to a substrate (21) via the multiple connecting beams (24); the pressure sensor (10) includes a carrier plate (11) and multiple piezoresistive elements (12), the surface of the piezoresistive elements (12) near the accelerometer structure layer (20) is exposed by the carrier plate (11). A method for fabricating a composite sensor is also provided.

Description

Composite Sensor and Its Fabrication Method

[0001] This application claims priority to Chinese Patent Application No. 202510162347.4, filed on February 13, 2025, entitled "Pressure Sensor and Method for Preparation Thereof", the contents of which shall be construed as incorporated herein by reference. Technical Field

[0002] This article relates to, but is not limited to, the field of microelectromechanical systems (MEMS) technology, and in particular to a composite sensor and its fabrication method. Background Technology

[0003] In recent years, Micro-electro-mechanical systems (MEMS) have emerged as a revolutionary technology, deeply integrating information sensing and signal processing technologies. This has significantly improved instrument performance and expanded its application scope, demonstrating immense potential. MEMS utilizes integrated circuit manufacturing and micro / nano fabrication technologies to integrate microsensors, signal processing units, and micro-actuators, forming microsystems capable of information sensing, processing, and structural execution. This will increase the integration level of current instrument systems, reduce equipment cost and size, and meet the development needs of fields such as aerospace, microwave communications, and artificial intelligence. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0005] On one hand, embodiments of this disclosure provide a composite sensor, including:

[0006] Pressure sensor;

[0007] An accelerometer structure layer is stacked on top of the pressure sensor. The accelerometer structure layer includes a substrate and a first cavity disposed in the substrate, wherein the first cavity penetrates the substrate in a direction perpendicular to the plane of the composite sensor. The accelerometer structure layer also includes a suspended structure, multiple connecting beams, and multiple electrical bridges, wherein the multiple electrical bridges constitute at least one of a first Wheatstone bridge, a second Wheatstone bridge, and a third Wheatstone bridge. The suspended structure is located within the first cavity, the multiple connecting beams are arranged around the suspended structure, and the suspended structure is connected to the substrate via the multiple connecting beams. A portion of the electrical bridges is embedded in the substrate from the surface of the substrate away from the pressure sensor.

[0008] In some exemplary embodiments, each of the bridge circuits includes at least one varistor whose orthographic projection on the plane of the composite sensor lies within the orthographic projection of the suspended structure on the plane of the composite sensor, or the orthographic projection of the varistor on the plane of the composite sensor lies within the orthographic projection of the connecting beam on the plane of the composite sensor.

[0009] In some exemplary embodiments, the plurality of connecting beams includes a first connecting beam, a second connecting beam, a third connecting beam, and a fourth connecting beam; the first connecting beam and the third connecting beam are respectively located on both sides of the suspended structure along a first direction, and the second connecting beam and the fourth connecting beam are respectively located on both sides of the suspended structure along a second direction; the first direction and the second direction intersect and the plane formed thereby is parallel to the plane where the composite sensor is located.

[0010] In some exemplary embodiments, the plurality of bridges includes a first bridge, a second bridge, a third bridge, and a fourth bridge, and the first bridge, the second bridge, the third bridge, and the fourth bridge constitute a first Wheatstone bridge; the first bridge, the second bridge, and the second connecting beam are arranged in a group, and the orthographic projections of the varistor of the first bridge and the varistor of the second bridge on the plane where the composite sensor is located are both located within the orthographic projection of the second connecting beam on the plane where the composite sensor is located;

[0011] The third bridge, the fourth bridge, and the fourth connecting beam are arranged in a group. The orthographic projections of the varistor of the third bridge and the varistor of the fourth bridge onto the plane where the composite sensor is located are both located within the orthographic projection of the fourth connecting beam onto the plane where the composite sensor is located.

[0012] In some exemplary embodiments, the plurality of bridges includes a fifth bridge, a sixth bridge, a seventh bridge, and an eighth bridge, and the fifth bridge, the sixth bridge, the seventh bridge, and the eighth bridge constitute the second Wheatstone bridge; the fifth bridge, the sixth bridge, and the first connecting beam are arranged in a group, and the orthographic projections of the varistor of the fifth bridge and the varistor of the sixth bridge on the plane where the composite sensor is located are both located within the orthographic projection of the first connecting beam on the plane where the composite sensor is located;

[0013] The seventh bridge, the eighth bridge, and the third connecting beam are arranged in a group. The orthographic projections of the varistor of the seventh bridge and the varistor of the eighth bridge on the plane where the composite sensor is located are both located within the orthographic projection of the third connecting beam on the plane where the composite sensor is located.

[0014] In some exemplary embodiments, each of the connecting beams includes a first end and a second end disposed opposite to each other, the first end being connected to the suspended structure and the second end being connected to the substrate; the second end of the first connecting beam is provided with at least one hollow area, and the hollow area penetrates the first connecting beam in a direction perpendicular to the plane where the composite sensor is located; the second end of the third connecting beam is provided with at least one hollow area, and the hollow area penetrates the third connecting beam in a direction perpendicular to the plane where the composite sensor is located.

[0015] In some exemplary embodiments, the plurality of bridges includes a ninth bridge, a tenth bridge, an eleventh bridge, and a twelfth bridge, and the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge constitute the third Wheatstone bridge; the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge are respectively arranged in a one-to-one correspondence with the first connecting beam, the second connecting beam, the third connecting beam, and the fourth connecting beam, respectively; the bridge constituting the third Wheatstone bridge surrounds at least a portion of the corresponding connecting beam; the orthographic projection of the bridge constituting the third Wheatstone bridge onto the plane where the composite sensor is located does not overlap with the orthographic projection of the corresponding connecting beam onto the plane where the composite sensor is located; and the orthographic projection of the varistor constituting the third Wheatstone bridge onto the plane where the composite sensor is located is within the orthographic projection of the suspended structure onto the plane where the composite sensor is located.

[0016] In some exemplary embodiments, the plurality of bridges includes a ninth bridge, a tenth bridge, an eleventh bridge, and a twelfth bridge, and the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge constitute the third Wheatstone bridge; the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge are respectively arranged in a one-to-one correspondence with the first connecting beam, the second connecting beam, the third connecting beam, and the fourth connecting beam, and the orthographic projection of the bridge constituting the third Wheatstone bridge onto the plane where the composite sensor is located overlaps with the orthographic projection of the corresponding connecting beam onto the plane where the composite sensor is located, and the orthographic projection of the varistor of the bridge constituting the third Wheatstone bridge onto the plane where the composite sensor is located is located within the orthographic projection of the suspended structure onto the plane where the composite sensor is located.

[0017] In some exemplary embodiments, each of the connecting beams includes a first end and a second end disposed opposite to each other, the first end being connected to the suspended structure and the second end being connected to the substrate; at least one of the connecting beams has at least one notch at its first end, and the notch extends through the connecting beam in a direction perpendicular to the plane of the composite sensor.

[0018] In some exemplary embodiments, each of the connecting beams includes a first side and a second side disposed opposite to each other along its width direction, and at least one of the connecting beams has at least one first notch and at least one second notch at its first end, the first notch being recessed from one side of the first side toward one side of the second side, and the second notch being recessed from one side of the second side toward one side of the first side; the width direction is parallel to the plane where the composite sensor is located.

[0019] In some exemplary embodiments, the accelerometer structure layer further includes a protrusion structure located on the side of the suspended structure near the pressure sensor and connected to the suspended structure. The orthographic projection of the protrusion structure onto the plane of the composite sensor is located within the orthographic projection of the suspended structure onto the plane of the composite sensor.

[0020] In some exemplary embodiments, the suspended structure has a plurality of first release holes and a plurality of second release holes, the plurality of second release holes being arranged around the protruding structure, and the plurality of first release holes being arranged around the periphery of the plurality of second release holes.

[0021] In some exemplary embodiments, the pressure sensor includes a carrier plate, the carrier plate including a pressure-sensitive diaphragm and a second cavity, the second cavity being located on the side of the pressure-sensitive diaphragm near the accelerometer structural layer, and the second cavity being located inside the carrier plate.

[0022] In some exemplary embodiments, a plurality of the second cavities are arranged at intervals along a direction parallel to the plane in which the composite sensor is located.

[0023] In some exemplary embodiments, the pressure sensor includes a carrier plate, the carrier plate including a pressure-sensitive diaphragm and a second cavity, the second cavity being located on the side of the pressure-sensitive diaphragm away from the accelerometer structure layer, and the second cavity being recessed from the side of the carrier plate away from the accelerometer structure layer toward the direction closer to the accelerometer structure layer.

[0024] On the other hand, this disclosure provides a method for fabricating a composite sensor, the composite sensor comprising a pressure sensor and an accelerometer structure layer stacked together; the fabrication method includes:

[0025] A sacrificial film is formed on one side of a semiconductor material layer. The sacrificial film is patterned using a patterning process to form a sacrificial film pattern. The sacrificial film pattern has multiple vias, and the vias expose a portion of the surface of the semiconductor material layer.

[0026] Based on the via, an epitaxial layer is formed on the side of the sacrificial thin film pattern away from the semiconductor material layer using a selective epitaxial process;

[0027] Ion implantation is performed on a portion of the surface of the epitaxial layer away from the semiconductor material layer to form multiple electrical bridges in the accelerometer structure layer, and the multiple electrical bridges constitute at least one of a first Wheatstone bridge, a second Wheatstone bridge, and a third Wheatstone bridge.

[0028] The epitaxial layer is etched from the side of the epitaxial layer away from the semiconductor material layer to form a first cavity of the accelerometer structure layer, and the epitaxial layer forms the substrate, suspended structure and multiple connecting beams of the accelerometer structure layer.

[0029] In some exemplary embodiments, ion implantation is performed on a portion of the surface of the epitaxial layer away from the semiconductor material layer to form multiple bridges of the accelerometer structure layer, including:

[0030] A double-sided ion implantation process is used to implant ions into a portion of the surface of the epitaxial layer away from the semiconductor material layer to form the electrical bridge, and to implant ions into a portion of the surface of the semiconductor material layer away from the epitaxial layer to form the piezoresistive element of the pressure sensor.

[0031] In some exemplary embodiments, before forming a sacrificial film on one side of the semiconductor material layer, the preparation method further includes:

[0032] The semiconductor material layer is etched to form a well array pattern, and the well array pattern includes multiple wells;

[0033] The semiconductor material layer is annealed to form the second cavity and pressure-sensing diaphragm of the pressure sensor, wherein the pressure-sensing diaphragm is farther away from the accelerometer structure layer than the second cavity.

[0034] In some exemplary embodiments, before forming a sacrificial film on one side of the semiconductor material layer, the preparation method further includes:

[0035] The semiconductor material layer is etched to form a well array pattern, and the well array pattern includes multiple wells;

[0036] The preparation method further includes: after forming the epitaxial layer, annealing the semiconductor material layer to form a plurality of second cavities and a pressure-sensing film of the pressure sensor, wherein the pressure-sensing film is farther away from the accelerometer structure layer than the plurality of second cavities.

[0037] In some exemplary embodiments, patterning the sacrificial film to form a sacrificial film pattern using a patterning process includes: the sacrificial film pattern having three through holes, and the three through holes being arranged sequentially along a direction parallel to the plane of the composite sensor;

[0038] The epitaxial layer formed based on the via includes: the epitaxial layer located within the central via forms a protruding structure of the accelerometer structure layer.

[0039] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood.

[0040] Overview of the attached figures

[0041] The accompanying drawings are used to provide an understanding of the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure.

[0042] Figure 1 is a top view schematic diagram of a composite sensor according to an embodiment of the present disclosure;

[0043] Figure 2 is a cross-sectional view of the section marked AA in Figure 1;

[0044] Figure 3A is an enlarged schematic diagram of the ninth bridge of a composite sensor according to an embodiment of the present disclosure;

[0045] Figure 3B is an enlarged schematic diagram of the tenth bridge of a composite sensor according to an embodiment of the present disclosure;

[0046] Figure 4 is a cross-sectional view of a composite sensor according to an embodiment of the present disclosure after a groove has been formed;

[0047] Figure 5 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after the encapsulation layer is formed;

[0048] Figure 6 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after forming a well array pattern;

[0049] Figure 7 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after forming a pressure-sensitive membrane;

[0050] Figure 8 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after forming a sacrificial film pattern;

[0051] Figure 9 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after the epitaxial layer is formed;

[0052] Figure 10 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after forming a bridge;

[0053] Figure 11 is a cross-sectional view of a composite sensor according to an embodiment of the present disclosure after forming a conductive connection hole;

[0054] Figure 12 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after an insulating layer has been formed;

[0055] Figure 13 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after the transfer electrode is formed;

[0056] Figure 14 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after a protective layer has been formed;

[0057] Figure 15 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after forming a suspended structure;

[0058] Figure 16 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after the formation of a sacrificial layer;

[0059] Figure 17 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after the encapsulation layer is bonded to the pressure sensor;

[0060] Figure 18 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after conductive leads have been formed;

[0061] Figure 19 is a cross-sectional schematic diagram of a composite sensor according to an embodiment of the present disclosure after the protective layer is formed;

[0062] Figure 20 is a top view schematic diagram of a composite sensor according to another embodiment of the present disclosure;

[0063] Figure 21 is a cross-sectional view of the section marked BB in Figure 20;

[0064] Figure 22A is a schematic diagram of the Wheatstone bridge of the first accelerometer of the composite sensor according to another embodiment of the present disclosure;

[0065] Figure 22B is a schematic diagram of the Wheatstone bridge of the second accelerometer of the composite sensor according to another embodiment of the present disclosure;

[0066] Figure 22C is a schematic diagram of the Wheatstone bridge of the third accelerometer of the composite sensor according to another embodiment of the present disclosure;

[0067] Figure 23 is an enlarged schematic diagram of the first connecting beam of a composite sensor according to another embodiment of the present disclosure;

[0068] Figure 24A is an enlarged schematic diagram of the ninth bridge of a composite sensor according to another embodiment of the present disclosure;

[0069] Figure 24B is an enlarged schematic diagram of the tenth bridge of a composite sensor according to another embodiment of the present disclosure;

[0070] Figure 24C is an enlarged schematic diagram of the first bridge of a composite sensor according to another embodiment of the present disclosure;

[0071] Figure 25 is a cross-sectional schematic diagram of a composite sensor according to another embodiment of the present disclosure after the epitaxial layer is formed;

[0072] Figure 26 is a cross-sectional schematic diagram of the carrier plate of a composite sensor according to another embodiment of the present disclosure;

[0073] Figure 27 is a cross-sectional schematic diagram of a composite sensor according to another embodiment of the present disclosure.

[0074] Detailed Explanation

[0075] The embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The implementation can be carried out in many different forms. Those skilled in the art will readily understand that the methods and content can be changed to one or more forms without departing from the spirit and scope of this disclosure. Therefore, this disclosure should not be construed as limited to the content described in the following embodiments. Without conflict, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0076] In the accompanying drawings, the size of one or more constituent elements, the thickness of layers, or areas are sometimes exaggerated for clarity. Therefore, this disclosure is not necessarily limited to these dimensions, and the shapes and sizes of the components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate ideal examples, and this disclosure is not limited to the shapes or values ​​shown in the drawings.

[0077] The ordinal numbers such as "first," "second," and "third" in this disclosure are used to avoid confusion among the constituent elements, not to limit the quantity. "Multiple" in this disclosure includes two or more quantities.

[0078] In this disclosure, for convenience, terms such as "middle," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer" are used to indicate orientation or positional relationships in conjunction with the accompanying drawings. This is solely for the purpose of facilitating the description and simplification of the specification, and does not imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this disclosure. The positional relationships of the constituent elements may be appropriately changed depending on the direction in which the constituent elements are described. Therefore, the description is not limited to the terms used in the specification and may be appropriately replaced as appropriate.

[0079] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection via an intermediate component, or a connection within two components. Those skilled in the art will understand the meaning of these terms in this disclosure as appropriate.

[0080] In this disclosure, a transistor is a device that includes at least three terminals: a gate electrode, a drain electrode, and a source electrode. A transistor has a channel region between the drain electrode (drain electrode terminal, drain region, or drain) and the source electrode (source electrode terminal, source region, or source), and current can flow through the drain electrode, the channel region, and the source electrode. In this disclosure, the channel region refers to the region through which current primarily flows.

[0081] In this disclosure, the first electrode can be the drain electrode and the second electrode can be the source electrode, or vice versa. In cases where transistors with opposite polarities are used or the current direction changes during circuit operation, the functions of the "source electrode" and the "drain electrode" are sometimes interchanged. Therefore, in this disclosure, the "source electrode" and the "drain electrode" can be interchanged.

[0082] In this disclosure, "electrical connection" includes the situation where constituent elements are connected together by a component having a certain electrical function. There are no particular limitations on the "component having a certain electrical function," as long as it enables the transmission of electrical signals between the connected constituent elements. Examples of "component having a certain electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other components having one or more functions.

[0083] In this disclosure, "parallel" refers to a state in which the angle formed by two straight lines is greater than or equal to -10° and less than 10°, and therefore can include a state in which the angle is greater than or equal to -5° and less than 5°. Furthermore, "perpendicular" refers to a state in which the angle formed by two straight lines is greater than or equal to 80° and less than 100°, and therefore can include a state in which the angle is greater than or equal to 85° and less than 95°.

[0084] In this disclosure, the terms "film" and "layer" can be interchanged. For example, sometimes "conductive layer" can be replaced with "conductive film". Similarly, sometimes "insulating film" can be replaced with "insulating layer".

[0085] In this disclosure, “about” means a value that is not strictly limited and allows for process and measurement errors.

[0086] This disclosure provides a composite sensor, including:

[0087] Pressure sensor;

[0088] An accelerometer structure layer is stacked on top of the pressure sensor. The accelerometer structure layer includes a substrate and a first cavity disposed in the substrate, wherein the first cavity penetrates the substrate in a direction perpendicular to the plane of the composite sensor. The accelerometer structure layer also includes a suspended structure, multiple connecting beams, and multiple electrical bridges, wherein the multiple electrical bridges constitute at least one of a first Wheatstone bridge, a second Wheatstone bridge, and a third Wheatstone bridge. The suspended structure is located within the first cavity, the multiple connecting beams are arranged around the suspended structure, and the suspended structure is connected to the substrate via the multiple connecting beams. A portion of the electrical bridges is embedded in the substrate from the surface of the substrate away from the pressure sensor.

[0089] In this embodiment of the disclosure, by designing the accelerometer structure layer to include a suspended structure, multiple connecting beams and multiple Wheatstone bridges, and the multiple Wheatstone bridges constitute at least one of a first Wheatstone bridge, a second Wheatstone bridge and a third Wheatstone bridge, the composite sensor can detect acceleration in at least one of the first direction, the second direction and the third direction, and has high detection sensitivity, and can be applied to a variety of detection scenarios.

[0090] Figure 1 is a top view of a composite sensor according to an embodiment of this disclosure, and Figure 2 is a cross-sectional view of the area marked AA in Figure 1. As shown in Figures 1 and 2, the first direction X and the second direction Y intersect and form a plane. The plane where the composite sensor is located is parallel to the plane formed by the first direction X and the second direction Y. For example, the first direction X and the second direction Y are perpendicular to each other. The composite sensor may include a pressure sensor 10, an accelerometer structure layer 20, and an encapsulation layer 30, which are stacked sequentially along a third direction Z. In Figure 1, the encapsulation layer 30 is not shown to facilitate identification of the structure of the accelerometer structure layer 20. In this embodiment of the disclosure, stacking the pressure sensor and the accelerometer structure layer can reduce the area occupied by the composite sensor, which is beneficial for miniaturizing the composite sensor design. The third direction Z is perpendicular to the plane formed by the first direction X and the second direction Y. In this embodiment of the disclosure, the third direction Z can also be referred to as the thickness direction of the composite sensor. In some examples, the composite sensor also includes at least one of a temperature sensor and a gyroscope, which is not limited in this disclosure.

[0091] As shown in Figures 1 and 2, the accelerometer structure layer 20 may include a substrate 21 and a first cavity 22 disposed on the substrate 21. The edge of the substrate 21 in the orthographic projection of the plane where the composite sensor is located may be rectangular. The first cavity 22 may penetrate the substrate 21 along a third direction Z. The first cavity 22 may be a rectangular cavity. The accelerometer structure layer 20 may also include a suspended structure 23 and a plurality of connecting beams 24 surrounding the suspended structure 23. For example, four connecting beams 24 are evenly distributed around the suspended structure 23. The suspended structure 23 is located within the first cavity 22 and is connected to the substrate 21 via the plurality of connecting beams 24.

[0092] The orthographic projection of the connecting beam 24 onto the plane of the composite sensor can be rectangular. Each connecting beam 24 includes a first end and a second end arranged opposite each other along its extension direction. For example, the first end and the second end can each occupy 1 / 3, 1 / 4, or 1 / 5 of the extension direction of the connecting beam 24, etc. The connecting beam 24 excluding the first end and the second end can be referred to as the middle part. That is, each connecting beam 24 can include a first end, a middle part, and a second end arranged sequentially along its extension direction. Taking the accelerometer structure layer 20 as an example, which includes four connecting beams 24, namely the first connecting beam 241, the second connecting beam 242, the third connecting beam 243, and the fourth connecting beam 244. The first connecting beam 241 and the third connecting beam 243 are located on both sides of the suspended structure 23 along the first direction X. The second connecting beam 242 and the fourth connecting beam 244 are located on both sides of the suspended structure 23 along the second direction Y. For example, the first connecting beam 241, the second connecting beam 242, the third connecting beam 243, and the fourth connecting beam 244 can be arranged in a clockwise direction.

[0093] A first connecting beam 241 extends along a first direction X. A first end of the first connecting beam 241 is connected to the suspended structure 23, which can be a direct connection, for example. A second end of the first connecting beam 241 is located on one side of its first end along the first direction X and is connected to the substrate 21, which can also be a direct connection, for example. Alternatively, the first connecting beam 241 can be located between the suspended structure 23 and the substrate 21. A second connecting beam 242 extends along a second direction Y. A first end of the second connecting beam 242 is connected to the suspended structure 23, which can be a direct connection, for example. A second end of the second connecting beam 242 is located on one side of its first end along the second direction Y and is connected to the substrate 21, which can also be a direct connection, for example. Alternatively, the second connecting beam 242 can be located between the suspended structure 23 and the substrate 21. The third connecting beam 243 extends along the first direction X. The first end of the third connecting beam 243 is connected to the suspended structure 23, which can be a direct connection, as an example. The second end of the third connecting beam 243 is located on the side opposite to its first end along the first direction X and is connected to the substrate 21, which can also be a direct connection, as an example. Alternatively, the third connecting beam 243 can be located between the suspended structure 23 and the substrate 21. The fourth connecting beam 244 extends along the second direction Y. The first end of the fourth connecting beam 244 is connected to the suspended structure 23, which can be a direct connection, as an example. The second end of the fourth connecting beam 244 is located on the side opposite to its first end along the second direction Y and is connected to the substrate 21, which can also be a direct connection, as an example. Alternatively, the fourth connecting beam 244 can be located between the suspended structure 23 and the substrate 21. Alternatively, the four connecting beams 24 can be designed symmetrically about the first centerline L1 and about the second centerline L2. The first center line L1 is a straight line passing through the center of the suspended structure 23 and extending along the first direction X, and the second center line L2 is a straight line passing through the center of the suspended structure 23 and extending along the second direction Y.

[0094] The accelerometer structure layer 20 may also include multiple electrical bridges 25, for example, four electrical bridges 25, which may be distributed around the center of the suspended structure 23. For example, the four electrical bridges 25 are evenly distributed around the center of the suspended structure 23. The multiple electrical bridges 25 are arranged in a one-to-one correspondence with multiple connecting beams 24, and the orthographic projection of the electrical bridge 25 onto the plane of the composite sensor at least partially overlaps with the orthographic projection of the corresponding connecting beam 24 onto the plane of the composite sensor. For example, the orthographic projection of the electrical bridge 25 onto the plane of the composite sensor partially overlaps with the orthographic projection of the corresponding connecting beam 24 onto the plane of the composite sensor, and the orthographic projection of the electrical bridge 25 onto the plane of the composite sensor partially overlaps with the orthographic projection of the suspended structure 23 onto the plane of the composite sensor, and the orthographic projection of the electrical bridge 25 onto the plane of the composite sensor partially overlaps with the orthographic projection of the substrate 21 onto the plane of the composite sensor. A portion of the electrical bridge 25 may be embedded into the interior of the connecting beam 24 from the surface of the corresponding connecting beam away from the pressure sensor 10. A portion of the bridge 25 can be embedded into the interior of the substrate 21 from the surface of the substrate 21 away from the pressure sensor 10. A portion of the bridge 25 can be embedded into the interior of the suspended structure 23 from the surface of the suspended structure 23 away from the pressure sensor 10. The surface of the bridge 25 away from the pressure sensor 10 is exposed by the connecting beam 24, the substrate 21, and the suspended structure 23.

[0095] The accelerometer structure layer 20 may include at least one accelerometer, and each accelerometer includes multiple bridges 25. For example, the accelerometer structure layer 20 may include three accelerometers: a first accelerometer, a second accelerometer, and a third accelerometer 20-3. The first accelerometer is used to detect the acceleration received by the composite sensor along a first direction X; the second accelerometer is used to detect the acceleration received by the composite sensor along a second direction Y; and the third accelerometer 20-3 is used to detect the acceleration received by the composite sensor along a third direction Z. The first and second accelerometers will be described in subsequent embodiments, which primarily use the third accelerometer 20-3 as an example.

[0096] The third accelerometer 20-3 includes four bridges 25, namely the ninth bridge 2509, the tenth bridge 2510, the eleventh bridge 2511, and the twelfth bridge 2512, which form a third Wheatstone bridge. In practical applications, when the composite sensor is subjected to acceleration along the third direction Z, the resistance of the ninth bridge 2509 and the eleventh bridge 2511 increases, while the resistance of the tenth bridge 2510 and the twelfth bridge 2512 decreases; or, the resistance of the ninth bridge 2509 and the eleventh bridge 2511 decreases, while the resistance of the tenth bridge 2510 and the twelfth bridge 2512 increases. The third Wheatstone bridge differentially outputs an electrical signal, which can be a voltage signal or a current signal. Then, using finite element simulation tools, the stress in the third direction Z experienced by the composite sensor is analyzed.

[0097] The ninth bridge 2509 is configured in a one-to-one correspondence with the first connecting beam 241, and the orthographic projection of the ninth bridge 2509 onto the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding first connecting beam 241 onto the plane where the composite sensor is located. The tenth bridge 2510 is configured in a one-to-one correspondence with the second connecting beam 242, and the orthographic projection of the tenth bridge 2510 onto the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding second connecting beam 242 onto the plane where the composite sensor is located. The eleventh bridge 2511 is configured in a one-to-one correspondence with the third connecting beam 243, and the orthographic projection of the eleventh bridge 2511 onto the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding third connecting beam 243 onto the plane where the composite sensor is located. The twelfth bridge 2512 is configured in a one-to-one correspondence with the fourth connecting beam 244, and the orthographic projection of the twelfth bridge 2512 onto the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding fourth connecting beam 244 onto the plane where the composite sensor is located.

[0098] In some exemplary embodiments, each bridge 25 includes at least one piezoresistor, the orthographic projection of which onto the plane of the composite sensor lies within the orthographic projection of the suspended structure 23 onto the plane of the composite sensor, or the orthographic projection of which onto the plane of the composite sensor lies within the orthographic projection of the connecting beam 24 onto the plane of the composite sensor. The orthographic projection of the piezoresistor of the third accelerometer 20-3 onto the plane of the composite sensor lies within the orthographic projection of the suspended structure 23 onto the plane of the composite sensor.

[0099] In some exemplary embodiments, the ninth bridge 2509, the tenth bridge 2510, the eleventh bridge 2511, and the twelfth bridge 2512 are respectively arranged in correspondence with the first connecting beam 241, the second connecting beam 242, the third connecting beam 243, and the fourth connecting beam 244, and the orthographic projection of the bridge 25 of the third accelerometer 20-3 on the plane where the composite sensor is located overlaps with the orthographic projection of the corresponding connecting beam 24 on the plane where the composite sensor is located.

[0100] In some exemplary embodiments, as shown in FIG1, the substrate 21, the suspended structure 23, and the plurality of connecting beams 24 can be an integral structure that is interconnected.

[0101] In some exemplary embodiments, as shown in Figures 1 and 2, the orthographic projection range of the suspended structure 23 onto the plane where the composite sensor is located can be rectangular. The suspended structure 23 has multiple first release holes 231, which can penetrate the suspended structure 23 along a third direction Z. In Figure 2, the number of first release holes 231 is simplified. The first release holes 231 can be rectangular holes, circular holes, elliptical holes, etc. The multiple first release holes 231 can be arranged in a rectangular array or a circular array, etc.

[0102] In some exemplary embodiments, as shown in FIG2, the pressure sensor 10 may include a carrier plate 11 and a plurality of piezoresistive elements 12. The piezoresistive elements 12 may be embedded in the carrier plate 11 from the surface of the carrier plate 11 away from the accelerometer structure layer 20, and the surface of the piezoresistive elements 12 away from the accelerometer structure layer 20 is exposed by the carrier plate 11.

[0103] In some exemplary embodiments, as shown in FIG2, the carrier plate 11 includes a pressure-sensitive diaphragm 11a and a second cavity 11b, the second cavity 11b being located on the side of the pressure-sensitive diaphragm 11a near the accelerometer structure layer 20, and the second cavity 11b being located inside the carrier plate 11. At least a portion of the piezoresistive element 12 can be embedded within the pressure-sensitive diaphragm 11a from the side of the pressure-sensitive diaphragm 11a away from the accelerometer structure layer 20.

[0104] In some exemplary embodiments, as shown in FIG2, the pressure sensor 10 may further include a plurality of adapter electrodes 13, each adapter electrode 13 including a first extension 131 and a second extension 132 connected to each other. The first extension 131 may extend in a direction parallel to the plane of the composite sensor, and the first extension 131 is located on the side of the carrier plate 11 away from the accelerometer structure layer 20 and is in direct contact with the piezoresistive element 12. The second extension 132 may extend in a third direction Z and is located on the side of the first extension 131 near the accelerometer structure layer 20. The second extension 132 may be embedded inside the carrier plate 11, and the end face of the second extension 132 away from the first extension 131 is exposed by the carrier plate 11. In the embodiments of this disclosure, by using the designed adapter electrodes, the electrical signal detected by the pressure sensor can be transmitted in a third direction, which can reduce the occupied area of ​​the pressure sensor, and thus reduce the occupied area of ​​the composite sensor.

[0105] Figure 3A is an enlarged schematic diagram of the ninth bridge of a composite sensor according to an embodiment of the present disclosure. As shown in Figures 3A and 1, each bridge 25 includes at least one varistor connected to it and multiple connecting electrodes, wherein the resistivity of the varistor is greater than the resistivity of the connecting electrodes. Taking the ninth bridge 2509 as an example, the ninth bridge 2509 may include two varistors and three connecting electrodes, wherein the two varistors are a first varistor 2521 and a second varistor 2522, and the three connecting electrodes are a first connecting electrode 2531, a second connecting electrode 2532, and a third connecting electrode 2533.

[0106] The orthographic projections of the first varistor 2521 and the second varistor 2522 onto the plane of the composite sensor can both be rectangles extending along the first direction X. The orthographic projections of the first varistor 2521 and the second varistor 2522 onto the plane of the composite sensor can both lie within the orthographic projection of the suspended structure 23 onto the plane of the composite sensor. The orthographic projection of the third connecting electrode 2533 onto the plane of the composite sensor can be a rectangle extending along the second direction Y. The orthographic projection of the third connecting electrode 2533 onto the plane of the composite sensor can also lie within the orthographic projection of the suspended structure 23 onto the plane of the composite sensor. The third connecting electrode 2533 can be located on the side of the first varistor 2521 opposite to the first direction X. The third connecting electrode 2533 can also be located on the side of the second varistor 2522 opposite to the first direction X. The end of the first varistor 2521 near the third connecting electrode 2533 is in direct contact with the third connecting electrode 2533, and the end of the second varistor 2522 near the third connecting electrode 2533 is also in direct contact with the third connecting electrode 2533.

[0107] The first connecting electrode 2531 is located on one side of the first varistor 2521 along the first direction X. The end of the first connecting electrode 2531 near the first varistor 2521 is in direct contact with the first varistor 2521. The portion of the first connecting electrode 2531 projected onto the plane of the composite sensor is located within the projected projection of the suspended structure 23 onto the plane of the composite sensor, and the portion of the first connecting electrode 2531 projected onto the plane of the composite sensor is located within the projected projection of the first connecting beam 241 onto the plane of the composite sensor, and the portion of the first connecting electrode 2531 projected onto the plane of the composite sensor is located within the projected projection of the substrate 21 onto the plane of the composite sensor. The projected projection of the first connecting electrode 2531 onto the plane of the composite sensor can be rectangular, L-shaped, or T-shaped, etc.

[0108] The second connecting electrode 2532 is located on one side of the second varistor 2522 along the first direction X. The end of the second connecting electrode 2532 near the second varistor 2522 is in direct contact with the second varistor 2522. The portion of the second connecting electrode 2532 projected onto the plane of the composite sensor is located within the projected projection of the suspended structure 23 onto the plane of the composite sensor, and the portion of the second connecting electrode 2532 projected onto the plane of the composite sensor is located within the projected projection of the first connecting beam 241 onto the plane of the composite sensor, and the portion of the second connecting electrode 2532 projected onto the plane of the composite sensor is located within the projected projection of the substrate 21 onto the plane of the composite sensor. The projected projection of the second connecting electrode 2532 onto the plane of the composite sensor can be rectangular, L-shaped, or T-shaped, etc.

[0109] The eleventh bridge 2511 can refer to the ninth bridge 2509. For example, the eleventh bridge 2511 and the ninth bridge 2509 can be designed symmetrically about the second center line L2, which is a straight line that passes through the center of the suspended structure 23 and extends along the second direction Y.

[0110] Figure 3B is an enlarged schematic diagram of the tenth bridge of a composite sensor according to an embodiment of the present disclosure. As shown in Figures 3B and 1, each bridge 25 includes at least one varistor and multiple connecting electrodes connected to it. Taking the tenth bridge 2510 as an example, the tenth bridge 2510 may include a varistor and two connecting electrodes. The varistor is a third varistor 2523, and the two connecting electrodes are a fourth connecting electrode 2534 and a fifth connecting electrode 2535.

[0111] The orthographic projection of the third varistor 2523 onto the plane of the composite sensor can be a rectangle extending along the first direction X. The orthographic projection of the third varistor 2523 onto the plane of the composite sensor can lie within the orthographic projection of the suspended structure 23 onto the plane of the composite sensor. The third varistor 2523 can be located between the fourth connecting electrode 2534 and the fifth connecting electrode 2535, and the fourth connecting electrode 2534 and the fifth connecting electrode 2535 are connected via the third varistor 2523.

[0112] The fourth connecting electrode 2534 is located on one side of the third varistor 2523 along the first direction X. The side of the fourth connecting electrode 2534 near the third varistor 2523 is in direct contact with the third varistor 2523. The portion of the fourth connecting electrode 2534 projected onto the plane of the composite sensor lies within the projection of the suspended structure 23 onto the plane of the composite sensor, and the portion of the fourth connecting electrode 2534 projected onto the plane of the composite sensor lies within the projection of the second connecting beam 242 onto the plane of the composite sensor, and the portion of the fourth connecting electrode 2534 projected onto the plane of the composite sensor lies within the projection of the substrate 21 onto the plane of the composite sensor. The projection of the fourth connecting electrode 2534 onto the plane of the composite sensor can be rectangular, L-shaped, or T-shaped, etc.

[0113] The fifth connecting electrode 2535 is located on the side of the third varistor 2523 opposite to the first direction X. The side of the fifth connecting electrode 2535 closest to the third varistor 2523 is in direct contact with it. The portion of the fifth connecting electrode 2535 projected onto the plane of the composite sensor lies within the projection of the suspended structure 23 onto the plane of the composite sensor, and the portion of the fifth connecting electrode 2535 projected onto the plane of the composite sensor lies within the projection of the second connecting beam 242 onto the plane of the composite sensor, and the portion of the fifth connecting electrode 2535 projected onto the plane of the composite sensor lies within the projection of the substrate 21 onto the plane of the composite sensor. The projection of the fifth connecting electrode 2535 onto the plane of the composite sensor can be rectangular, L-shaped, or T-shaped, etc.

[0114] The twelfth bridge 2512 can refer to the tenth bridge 2510. For example, the twelfth bridge 2512 and the tenth bridge 2510 can be designed symmetrically about the first center line L1, which is a straight line passing through the center of the suspended structure 23 and extending along the first direction X.

[0115] The following example illustrates the structure of a composite sensor through its fabrication process. The "patterning process" described in this disclosure includes, for metallic, inorganic, or transparent conductive materials, processes such as photoresist coating, mask exposure, development, etching, and photoresist stripping; for organic materials, it includes organic material coating, mask exposure, and development. Deposition can be performed using any one or more of sputtering, evaporation, and chemical vapor deposition; coating can be performed using any one or more of spraying, spin coating, and inkjet printing; etching can be performed using any one or more of dry and wet etching. This disclosure does not limit the methods used. A "thin film" refers to a thin film made of a material on a substrate using deposition, coating, or other processes. If the "thin film" does not require a patterning process during the entire fabrication process, it can also be called a "layer." If the "thin film" requires a patterning process during the entire fabrication process, it is called a "thin film" before the patterning process and a "layer" after the patterning process. The "layer" after the patterning process contains at least one "pattern." In the exemplary embodiments of this disclosure, "the orthographic projection of A includes the orthographic projection of B" means that the boundary of the orthographic projection of B falls within the boundary range of the orthographic projection of A, or the boundary of the orthographic projection of A overlaps with the boundary of the orthographic projection of B.

[0116] The fabrication of composite sensors includes the fabrication of an encapsulation layer. The fabrication process of the encapsulation layer may include:

[0117] (01) An etching process is used to etch the substrate 31 along the third direction Z to form a groove 32, as shown in FIG4. The groove 32 does not penetrate the substrate 31 along the third direction Z. For example, the substrate 31 can be quartz glass or borosilicate glass, etc. The etching process includes at least one of chemical etching and physical etching, and chemical etching can include at least one of dry etching and wet etching.

[0118] Subsequently, a portion of the substrate 31 is subjected to laser-induced modification treatment to form modified pillars 33, for example, four modified pillars 33 are formed. The four modified pillars 33 are located on both sides of the groove 32 along the second direction Y.

[0119] In some exemplary embodiments, the groove 32 and the modified column 33 can be prepared simultaneously, which can shorten the preparation cycle.

[0120] In some exemplary embodiments, a portion of the substrate 31 is first subjected to laser-induced modification treatment, and then the substrate 31 is etched along the third direction Z to form a groove 32.

[0121] (02) An etching process is used to etch away the modified pillar 33 so that the substrate 31 forms an encapsulation layer 30, as shown in Figure 5. The encapsulation layer 30 has multiple vias that penetrate the encapsulation layer 30 along a third direction Z. The multiple vias include at least a first via K1 and a second via K2. The first via K1 is closer to the groove 32 than the second via K2. The first via K1 is used to accommodate at least a first conductive lead formed in a subsequent process, and the second via K2 is used to accommodate at least a second conductive lead formed in a subsequent process.

[0122] The fabrication of the composite sensor also includes the fabrication of a pressure sensor and an accelerometer structural layer. The fabrication processes for the pressure sensor and the accelerometer structural layer may include:

[0123] (11) Forming a well array pattern includes using an etching process to etch the semiconductor material layer 14 along the third direction Z to form a well array pattern, as shown in FIG6. The well array pattern may include multiple wells 14a, and the semiconductor material layer 14 located within the wells 14a is etched away. The wells 14a do not penetrate the semiconductor material layer 14 along the third direction Z. The wells 14a are used to form a pressure-sensitive film and a second cavity in subsequent processes. For example, the material of the semiconductor material layer 14 may be monocrystalline silicon, etc.

[0124] In some exemplary embodiments, as shown in FIG6, well 14a has a depth H along a third direction Z, and the depth H can range from 2.0 micrometers to 6.0 micrometers. There is a gap S between two adjacent wells 14a, and the gap S can range from 2.0 micrometers to 6.0 micrometers.

[0125] In some exemplary embodiments, the shape of the orthographic projection of the well 14a onto the plane where the composite sensor is located can be circular or polygonal. For example, the polygon can be square, rectangle, hexagon, etc. Multiple wells 14a can be arranged in a rectangular array or a circular array, etc.

[0126] (12) Forming a pressure-sensitive film includes performing a high-temperature annealing process on the semiconductor material layer 14 that forms the well array pattern. The high-temperature annealing process can promote the migration of silicon atoms on the surface so that the bottoms of the multiple wells 14a are merged and the tops of the wells are closed to form a second cavity 11b and a pressure-sensitive film 11a, as shown in Figure 7.

[0127] In some exemplary embodiments, the thickness of the pressure-sensitive membrane 11a can range from 2.0 micrometers to 6.0 micrometers. The thickness direction is parallel to the third direction Z.

[0128] (13) Forming a sacrificial film pattern includes forming a sacrificial film on the surface of the semiconductor material layer 14 forming the aforementioned structure, on the side away from the pressure-sensitive film 11a, and patterning the sacrificial film using a patterning process to form a sacrificial film pattern 40a, as shown in FIG8. The sacrificial film pattern 40a has a plurality of vias 40b, within which the sacrificial film is etched away, exposing a portion of the surface of the semiconductor material layer 14. For example, the sacrificial film pattern 40a has two vias 40b along the second direction Y, with the two vias 40b located on opposite sides of the second cavity 11b. The vias 40b are used to prepare an epitaxial layer in subsequent processes using a selective epitaxial process.

[0129] In some exemplary embodiments, the material of the sacrificial film may include silicon oxynitride (SiO2). x N y ) or silicon nitride (SiN) x ) or silicon oxide (SiO) x ) or aluminum oxide (AlO) x ) or hafnium oxide (HfO) x At least one of the following:

[0130] In some exemplary embodiments, the thickness of the sacrificial film may be greater than or equal to 1.0 micrometer.

[0131] In some exemplary embodiments, the orthographic projection of the through-hole 40b onto the plane where the composite sensor is located can be a circle, a rectangle, or an ellipse, etc.

[0132] (14) Forming an epitaxial layer, including forming an epitaxial layer 20a on the side of the sacrificial thin film pattern 40a away from the semiconductor material layer 14 using a selective epitaxial process based on the via 40b, as shown in FIG9. The epitaxial layer 20a is used to form an accelerometer structure layer 20 in a subsequent process.

[0133] (15) Forming a bridge and a piezoresistive element includes using a double-sided ion implantation process to implant ions into a portion of the surface of the epitaxial layer 20a away from the semiconductor material layer 14 to form a bridge 25, and to implant ions into a portion of the surface of the semiconductor material layer 14 away from the epitaxial layer 20a to form a piezoresistive element 12, as shown in FIG10.

[0134] The material of the bridge 25 may include monocrystalline silicon and doped ions, and the doped ions may include at least one of boron (B) ions, phosphorus (P) ions, and arsenic (As) ions. The material of the piezoresistive element 12 may include monocrystalline silicon and doped ions, and the doped ions may include at least one of boron (B) ions, phosphorus (P) ions, and arsenic (As) ions.

[0135] Each bridge 25 includes at least one varistor and multiple connecting electrodes connected together, the resistivity of the varistor being greater than the resistivity of the connecting electrodes. For example, the doping ion concentration of the varistor differs from that of the connecting electrodes, with the varistor having a lower doping ion concentration than the connecting electrodes.

[0136] In some exemplary embodiments, the double-sided ion implantation process includes: coating a photoresist layer on the surface of the epitaxial layer 20a away from the semiconductor material layer 14 and on the surface of the semiconductor material layer 14 away from the epitaxial layer 20a; then exposing and developing the photoresist layer; then performing ion implantation on the epitaxial layer 20a and the semiconductor material layer 14 using the patterned photoresist layer; then performing an annealing process to activate the implanted dopant ions; and finally removing the photoresist layer and performing a cleaning process.

[0137] In some exemplary embodiments, the orthographic projection of the piezoresistive element 12 onto the plane of the composite sensor at least partially overlaps with the orthographic projection of the pressure-sensitive diaphragm 11a onto the plane of the composite sensor. The piezoresistive element 12 can be embedded into the pressure-sensitive diaphragm 11a from the side surface of the pressure-sensitive diaphragm 11a away from the second cavity 11b.

[0138] (16) Forming conductive interconnects includes using an etching process to etch the semiconductor material layer 14 from the side of the semiconductor material layer 14 away from the epitaxial layer 20a to form a carrier plate 11. The carrier plate 11 has a plurality of conductive interconnects 13a, as shown in FIG11. The conductive interconnects 13a penetrate the carrier plate 11 in a third direction Z and expose a portion of the surface of the epitaxial layer 20a. The conductive interconnects 13a are used to accommodate the transfer electrodes and insulating layers formed in subsequent processes. For example, a dry etching process can be used to form the conductive interconnects 13a.

[0139] In some exemplary embodiments, the orthographic projection of the conductive connection hole 13a onto the plane of the composite sensor does not overlap with the orthographic projection of the piezoresistive element 12 onto the plane of the composite sensor. Along the second direction Y, a plurality of conductive connection holes 13a may be located on both sides of the piezoresistive element 12.

[0140] In some exemplary embodiments, conductive connection holes 13a and through holes 40b can be provided in a one-to-one correspondence. The orthographic projection of the conductive connection hole 13a onto the plane where the composite sensor is located and the orthographic projection of the corresponding through hole 40b onto the plane where the composite sensor is located at least partially overlap, and the corresponding conductive connection hole 13a and through hole 40b are connected. For example, the orthographic projection of the conductive connection hole 13a onto the plane where the composite sensor is located and the orthographic projection of the corresponding through hole 40b onto the plane where the composite sensor is located can overlap.

[0141] In some exemplary embodiments, the orthographic projection of the conductive connection hole 13a onto the plane where the composite sensor is located can be circular, rectangular, or elliptical, etc.

[0142] (17) Forming an insulating layer includes depositing an insulating film based on the conductive connection hole 13a and patterning the insulating film using a patterning process to form an insulating layer 15, as shown in FIG12. The insulating layer 15 is located within the conductive connection hole 13a and does not fill the conductive connection hole 13a. The insulating layer 15 can be disposed around the hole wall of the conductive connection hole 13a.

[0143] In some exemplary embodiments, the material of the insulating layer 15 may include silicon oxynitride (SiO2). x N y ) or silicon nitride (SiN) x ) or silicon oxide (SiO) x ) or aluminum oxide (AlO) x ) or hafnium oxide (HfO) x At least one of the following. For example, the material of insulating layer 15 may be silicon oxide.

[0144] (18) Forming a transfer electrode includes forming a first conductive film based on the conductive connection hole 13a, and patterning the first conductive film using a patterning process to form a transfer electrode 13 partially located within the conductive connection hole 13a, as shown in FIG13. For example, the insulating layer 15 and the transfer electrode 13 may together fill the conductive connection hole 13a. For example, the first conductive film may be formed using a deposition process.

[0145] The adapter electrode 13 may include a first extension 131 and a second extension 132 connected to each other. The first extension 131 is located outside the conductive connection hole 13a and extends in a direction parallel to the plane of the composite sensor. The first extension 131 is located on the side of the piezoresistive element 12 away from the epitaxial layer 20a, and the first extension 131 is in direct contact with the piezoresistive element 12. The second extension 132 is located inside the conductive connection hole 13a, and the second extension 132 and the insulating layer 15 can together fill the conductive connection hole 13a.

[0146] In some possible exemplary embodiments, the transfer electrode is formed using an electroplating process.

[0147] In some exemplary embodiments, the material of the transfer electrode 13 may include a metallic material, such as any one or more of molybdenum (Mo), aluminum (Al), copper (Cu), and titanium (Ti). Alternatively, it may be an alloy of molybdenum (Mo), aluminum (Al), copper (Cu), and titanium (Ti), such as aluminum-neodymium alloy (AlNd), molybdenum-niobium alloy (MoNb), molybdenum-niobium-titanium alloy (MoNbTi), or molybdenum-nickel-titanium alloy (MoNiTi). The transfer electrode may be a single-layer structure or a multi-layer composite structure, such as Ti / Cu, MoNb / Cu, MoNiTi / Cu, TiN / Mo, Ti / Al / Ti, Mo / Nb / Cu, MoNb / Cu / MoNiTi, MoNiTi / Cu / MoNiTi, or Mo / Al / Mo, etc.

[0148] (19) Forming a protective layer includes sequentially depositing a first film layer 161 and a second film layer 162 on the side of the carrier plate 11 away from the epitaxial layer 20a to form a protective layer 16, as shown in FIG14. The materials of the first film layer 161 and the second film layer 162 can be the same or different. By designing two film layers, the composite sensor's resistance to water and oxygen can be improved, and its service life can be extended. For example, the material of the first film layer 161 can be silicon oxide, and the material of the second film layer 162 can be silicon nitride.

[0149] (20) Forming a suspended structure includes etching the epitaxial layer 20a from the side away from the carrier plate 11, so that the epitaxial layer 20a forms a substrate 21, a suspended structure 23, and a connecting beam 24, etc., and forms a first cavity 22 and a plurality of first release holes 231, as shown in FIG15. For example, a dry etching process can be used to etch the epitaxial layer 20a.

[0150] Forming the suspended structure may further include forming an isolation ring 20b, in which the epitaxial layer 20a within the isolation ring 20b is etched away, exposing a portion of the surface of the insulating layer 15, or the isolation ring 20b exposes a portion of the surface of the sacrificial film pattern 40a. The orthographic projection of the isolation ring 20b onto the plane of the composite sensor is annular. For example, the orthographic projection of the isolation ring 20b onto the plane of the composite sensor may surround the orthographic projection of the insulating layer 15 onto the plane of the composite sensor. Alternatively, the orthographic projection of the isolation ring 20b onto the plane of the composite sensor may overlap with the orthographic projection of the insulating layer 15 onto the plane of the composite sensor.

[0151] Forming the suspended structure may further include ion implantation of the epitaxial layer 20a surrounded by the isolation ring 20b to form a conductive structure 50, as shown in FIG15. The orthographic projection of the conductive structure 50 onto the plane of the composite sensor at least partially overlaps with the orthographic projection of the second extension 132 onto the plane of the composite sensor, and the surface of the conductive structure 50 near the carrier plate 11 is in direct contact with the surface of the second extension 132 near the suspended structure 23. For example, the orthographic projection of the conductive structure 50 onto the plane of the composite sensor overlaps with the orthographic projection of the second extension 132 onto the plane of the composite sensor.

[0152] In some possible exemplary embodiments, the conductive structure 50 is formed in the same step as the bridge 25 and the piezoresistive element 12, which can reduce the number of preparation steps, shorten the preparation cycle, and reduce the preparation cost.

[0153] (21) Forming a sacrificial layer, including the first cavity 22 and the first release hole 231 formed by the aforementioned process, etching the sacrificial film pattern 40a to remove the sacrificial film pattern 40a located on the side of the suspended structure 23 near the carrier plate 11, to form a sacrificial layer 40, as shown in FIG16. The orthographic projection of the sacrificial layer 40 on the plane where the composite sensor is located does not overlap with the orthographic projection of the suspended structure 23 on the plane where the composite sensor is located. For example, a vapor phase etching process is used to etch the sacrificial film pattern 40a.

[0154] (22) A bonding operation is performed, including bonding the encapsulation layer 30, pressure sensor 10, and accelerometer structure layer 20 formed in the aforementioned process. As shown in FIG17, the encapsulation layer 30 is located on the side of the accelerometer structure layer 20 away from the pressure sensor 10, and the groove 32 is located on the side close to the accelerometer structure layer 20. A first via K1 exposes a portion of the surface of the bridge 25. For example, one first via K1 exposes a portion of the surface of the tenth bridge 2510, and another first via K1 exposes a portion of the surface of the twelfth bridge 2512. The first via K1 is provided in a one-to-one correspondence with the bridge 25, and the first via K1 exposes a portion of the surface of the corresponding bridge 25. A second via K2 exposes a portion of the surface of the conductive structure 50. The second via K2 is provided in a one-to-one correspondence with the conductive structure 50, and the second via K2 exposes a portion of the surface of the corresponding conductive structure 50.

[0155] In some exemplary embodiments, hydrophilic treatment is applied to the encapsulation layer 30 and the accelerometer structure layer 20 before the bonding operation, which can improve the reliability of the bonding.

[0156] In some exemplary embodiments, anodic bonding can be used to bond the encapsulation layer 30, the pressure sensor 10, and the accelerometer structure layer 20.

[0157] (23) Forming conductive leads, including forming a second conductive film based on the first via K1 and the second via K2, and patterning the second conductive film using a patterning process to form conductive leads 60 that are at least partially located within the vias, as shown in FIG18. For example, the conductive leads 60 may fill the vias. For example, the second conductive film may be formed using a deposition process.

[0158] The conductive lead 60 includes a first conductive lead 61 and a second conductive lead 62. At least a portion of the first conductive lead 61 is located within a first via K1 and is in contact with the bridge 25. At least a portion of the second conductive lead 62 is located within a second via K2 and is in contact with the conductive structure 50.

[0159] In some possible exemplary embodiments, an electroplating process is used to form conductive leads.

[0160] In some exemplary embodiments, the material of the conductive lead may include a metallic material, such as any one or more of molybdenum (Mo), aluminum (Al), copper (Cu), and titanium (Ti). Alternatively, it may be an alloy of molybdenum (Mo), aluminum (Al), copper (Cu), and titanium (Ti), for example, an aluminum-neodymium alloy (AlNd), a molybdenum-niobium alloy (MoNb), a molybdenum-niobium-titanium alloy (MoNbTi), or a molybdenum-nickel-titanium alloy (MoNiTi). The conductive lead may be a single-layer structure or a multi-layer composite structure, such as Ti / Cu, MoNb / Cu, MoNiTi / Cu, TiN / Mo, Ti / Al / Ti, Mo / Nb / Cu, MoNb / Cu / MoNiTi, MoNiTi / Cu / MoNiTi, or Mo / Al / Mo, etc.

[0161] (24) Forming a protective layer, including forming conductive bumps 70, as shown in FIG19. The conductive bumps 70 are in contact with the conductive leads 60, and the conductive bumps 70 and the conductive leads 60 can be arranged in a one-to-one correspondence. The orthographic projection of the conductive bumps 70 onto the plane where the composite sensor is located can include the orthographic projection of the corresponding conductive leads 60 onto the plane where the composite sensor is located. For example, the conductive bumps 70 can be solder balls.

[0162] Subsequently, a protective layer 80 is formed. This protective layer 80 covers the contact interface between the conductive bumps 70 and the conductive leads 60, preventing water and oxygen from entering the composite sensor through this interface and improving the reliability of the composite sensor. For example, the protective layer 80 can be an oil layer, prepared using a coating process.

[0163] Figure 20 is a top view of a composite sensor according to another embodiment of this disclosure, and Figure 21 is a cross-sectional view of the section marked BB in Figure 20. As shown in Figures 20 and 21, the structure of the composite sensor is basically the same as that of the aforementioned embodiment, the main difference being that the accelerometer structure layer 20 may include multiple accelerometers, each of which includes multiple bridges 25. For example, the accelerometer structure layer 20 may include three accelerometers, namely a first accelerometer 20-1, a second accelerometer 20-2, and a third accelerometer 20-3. The first accelerometer 20-1 is used to detect the acceleration received by the composite sensor along the first direction X, the second accelerometer 20-2 is used to detect the acceleration received by the composite sensor along the second direction Y, and the third accelerometer 20-3 is used to detect the acceleration received by the composite sensor along the third direction Z. Alternatively, the accelerometer structure layer 20 may include any two of the three accelerometers. Alternatively, the accelerometer structure layer 20 may include any one of the three accelerometers.

[0164] The first accelerometer 20-1 includes four bridges 25, namely the first bridge 2501, the second bridge 2502, the third bridge 2503, and the fourth bridge 2504, which together form a first Wheatstone bridge. As shown in Figure 22A, in practical applications, when the composite sensor is subjected to acceleration along the first direction X, the resistance Rx1 of the first bridge 2501 and the resistance Rx3 of the third bridge 2503 increase, while the resistance Rx2 of the second bridge 2502 and the resistance Rx4 of the fourth bridge 2504 decrease. Alternatively, the resistance Rx1 of the first bridge 2501 and the resistance Rx3 of the third bridge 2503 decrease, while the resistance Rx2 of the second bridge 2502 and the resistance Rx4 of the fourth bridge 2504 increase. The first Wheatstone bridge differentially outputs an electrical signal, which can be a voltage signal or a current signal. Then, using finite element simulation tools, the stress on the composite sensor in the first direction X is analyzed. The first accelerometer 20-1 is more sensitive to the first direction X than to the second direction Y and the third direction Z, so as to improve the accuracy of acceleration detection in the first direction.

[0165] The second accelerometer 20-2 includes four bridges 25, namely the fifth bridge 2505, the sixth bridge 2506, the seventh bridge 2507, and the eighth bridge 2508, which together form a second Wheatstone bridge. As shown in Figure 22B, in practical applications, when the composite sensor is subjected to acceleration along the second direction Y, the resistance Ry1 of the fifth bridge 2505 and the resistance Ry3 of the seventh bridge 2507 increase, while the resistance Ry2 of the sixth bridge 2506 and the resistance Ry4 of the eighth bridge 2508 decrease. Alternatively, the resistances Ry1 of the fifth bridge 2505 and Ry3 of the seventh bridge 2507 decrease, while the resistances Ry2 of the sixth bridge 2506 and Ry4 of the eighth bridge 2508 increase. The second Wheatstone bridge differentially outputs an electrical signal, which can be a voltage signal or a current signal. Then, using finite element simulation tools, the stress in the second direction Y experienced by the composite sensor is analyzed. The second accelerometer 20-2 is more sensitive to the second direction Y than to the first direction X and the third direction Z, so as to improve the accuracy of acceleration detection in the second direction.

[0166] The third accelerometer 20-3 includes four bridges 25, namely the ninth bridge 2509, the tenth bridge 2510, the eleventh bridge 2511, and the twelfth bridge 2512. These four bridges 25 constitute the third Wheatstone bridge. As shown in Figure 22C, in practical applications, when the composite sensor is subjected to acceleration along the third direction Z, the resistances Rz1 of the ninth bridge 2509 and Rz3 of the eleventh bridge 2511 increase, while the resistances Rz2 of the tenth bridge 2510 and Rz4 of the twelfth bridge 2512 decrease. Alternatively, the resistances Rz1 of the ninth bridge 2509 and Rz3 of the eleventh bridge 2511 decrease, while the resistances Rz2 of the tenth bridge 2510 and Rz4 of the twelfth bridge 2512 increase. The third Wheatstone bridge differentially outputs an electrical signal, which can be a voltage signal or a current signal. Then, using finite element simulation tools, the stress in the third direction Z experienced by the composite sensor is analyzed.

[0167] In some exemplary embodiments, as shown in FIG20, the ninth bridge 2509, the tenth bridge 2510, the eleventh bridge 2511, and the twelfth bridge 2512 are respectively arranged in a one-to-one correspondence with the first connecting beam 241, the second connecting beam 242, the third connecting beam 243, and the fourth connecting beam 244. The bridges 25 of the third accelerometer 20-3 surround at least a portion of the correspondingly arranged connecting beams 24, and the orthographic projection of the bridges 25 on the plane where the composite sensor is located does not overlap with the orthographic projection of the correspondingly arranged connecting beams 24 on the plane where the composite sensor is located.

[0168] In some exemplary embodiments, as shown in FIG20, the first bridge 2501 and the second bridge 2502 are connected, and both the first bridge 2501 and the second bridge 2502 are correspondingly arranged with the second connecting beam 242. The orthographic projection of the first bridge 2501 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding second connecting beam 242 on the plane where the composite sensor is located. The orthographic projection of the second bridge 2502 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding second connecting beam 242 on the plane where the composite sensor is located. The orthographic projection of the first bridge 2501 on the plane where the composite sensor is located does not overlap with the orthographic projection of the suspended structure 23 on the plane where the composite sensor is located. The orthographic projection of the second bridge 2502 on the plane where the composite sensor is located does not overlap with the orthographic projection of the suspended structure 23 on the plane where the composite sensor is located. The tenth bridge 2510 may surround at least a portion of the first bridge 2501, and the tenth bridge 2510 may surround at least a portion of the second bridge 2502. The orthographic projection of the tenth bridge 2510 on the plane where the composite sensor is located does not overlap with the orthographic projection of the second connecting beam 242 on the plane where the composite sensor is located.

[0169] In some exemplary embodiments, as shown in FIG20, the third bridge 2503 and the fourth bridge 2504 are connected, and both the third bridge 2503 and the fourth bridge 2504 are correspondingly arranged with the fourth connecting beam 244. The orthographic projection of the third bridge 2503 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding fourth connecting beam 244 on the plane where the composite sensor is located. The orthographic projection of the fourth bridge 2504 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding fourth connecting beam 244 on the plane where the composite sensor is located. The orthographic projection of the third bridge 2503 on the plane where the composite sensor is located does not overlap with the orthographic projection of the suspended structure 23 on the plane where the composite sensor is located. The twelfth bridge 2512 may surround at least a portion of the third bridge 2503, and the twelfth bridge 2512 may surround at least a portion of the fourth bridge 2504. The orthographic projection of the twelfth bridge 2512 on the plane where the composite sensor is located does not overlap with the orthographic projection of the fourth connecting beam 244 on the plane where the composite sensor is located.

[0170] In some exemplary embodiments, as shown in FIG20, each bridge 25 of the first accelerometer 20-1 includes at least one piezoresistor, the orthographic projection of which onto the plane of the composite sensor lies within the orthographic projection of the corresponding connecting beam 24 onto the plane of the composite sensor. The first bridge 2501, the second bridge 2502, and the second connecting beam 242 are arranged in a group, and the orthographic projections of the piezoresistors of the first bridge 2501 and the second bridge 2502 onto the plane of the composite sensor lie within the orthographic projection of the second connecting beam 242 onto the plane of the composite sensor; the third bridge 2503, the fourth bridge 2504, and the fourth connecting beam 244 are arranged in a group, and the orthographic projections of the piezoresistors of the third bridge 2503 and the fourth bridge 2504 onto the plane of the composite sensor lie within the orthographic projection of the fourth connecting beam 244 onto the plane of the composite sensor.

[0171] In some exemplary embodiments, as shown in FIG20, the fifth bridge 2505 and the sixth bridge 2506 are connected, and both the fifth bridge 2505 and the sixth bridge 2506 are correspondingly arranged with respect to the first connecting beam 241. The orthographic projection of the fifth bridge 2505 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding first connecting beam 241 on the plane where the composite sensor is located. The orthographic projection of the sixth bridge 2506 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding first connecting beam 241 on the plane where the composite sensor is located. The orthographic projection of the fifth bridge 2505 on the plane where the composite sensor is located does not overlap with the orthographic projection of the suspended structure 23 on the plane where the composite sensor is located. The orthographic projection of the sixth bridge 2506 on the plane where the composite sensor is located does not overlap with the orthographic projection of the suspended structure 23 on the plane where the composite sensor is located. The ninth bridge 2509 may surround at least a portion of the fifth bridge 2505, and the ninth bridge 2509 may surround at least a portion of the sixth bridge 2506. The orthographic projection of the ninth bridge 2509 on the plane where the composite sensor is located does not overlap with the orthographic projection of the first connecting beam 241 on the plane where the composite sensor is located.

[0172] In some exemplary embodiments, as shown in FIG20, the seventh bridge 2507 and the eighth bridge 2508 are connected, and both the seventh bridge 2507 and the eighth bridge 2508 are correspondingly arranged with the third connecting beam 243. The orthographic projection of the seventh bridge 2507 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding third connecting beam 243 on the plane where the composite sensor is located. The orthographic projection of the eighth bridge 2508 on the plane where the composite sensor is located at least partially overlaps with the orthographic projection of the corresponding third connecting beam 243 on the plane where the composite sensor is located. The orthographic projection of the seventh bridge 2507 on the plane where the composite sensor is located does not overlap with the orthographic projection of the suspended structure 23 on the plane where the composite sensor is located. The eleventh bridge 2511 may surround at least a portion of the seventh bridge 2507, and the eleventh bridge 2511 may surround at least a portion of the eighth bridge 2508. The orthographic projection of the eleventh bridge 2511 onto the plane where the composite sensor is located does not overlap with the orthographic projection of the third connecting beam 243 onto the plane where the composite sensor is located. In this embodiment of the present disclosure, by rationally arranging multiple bridges, the composite sensor can achieve high-precision detection of acceleration in different directions after the suspended structure is subjected to acceleration in different directions, and also has high anti-interference capability.

[0173] In some exemplary embodiments, as shown in FIG20, each bridge 25 of the second accelerometer 20-2 includes at least one piezoresistor, the orthographic projection of which onto the plane of the composite sensor lies within the orthographic projection of the corresponding connecting beam 24 onto the plane of the composite sensor. The fifth bridge 2505, the sixth bridge 2506, and the first connecting beam 241 are grouped together, and the orthographic projections of the piezoresistors of the fifth bridge 2505 and the sixth bridge 2506 onto the plane of the composite sensor lie within the orthographic projection of the first connecting beam 241 onto the plane of the composite sensor. Similarly, the seventh bridge 2507, the eighth bridge 2508, and the third connecting beam 243 are grouped together, and the orthographic projections of the piezoresistors of the seventh bridge 2507 and the eighth bridge 2508 onto the plane of the composite sensor lie within the orthographic projection of the third connecting beam 243 onto the plane of the composite sensor.

[0174] In some exemplary embodiments, as shown in Figures 20 and 21, the accelerometer structure layer 20 may further include a protrusion structure 26. The protrusion structure 26 is located on the side of the suspended structure 23 near the pressure sensor 10 and is connected to the suspended structure 23. The orthographic projection of the protrusion structure 26 onto the plane of the composite sensor lies within the orthographic projection of the suspended structure 23 onto the plane of the composite sensor. The protrusion structure 26 may be centrally located on the suspended structure 23, and the center of the orthographic projection of the suspended structure 23 onto the plane of the composite sensor may lie within the orthographic projection of the protrusion structure 26 onto the plane of the composite sensor. For example, the center of the orthographic projection of the protrusion structure 26 onto the plane of the composite sensor may coincide with the center of the orthographic projection of the suspended structure 23 onto the plane of the composite sensor. The protrusion structure 26 and the suspended structure 23 may be an integral structure connected to each other. In the embodiments of this disclosure, by designing the protrusion structure, the signals in the first and second directions can be decoupled, and the sensitivity to the detection of acceleration in the third direction can be improved.

[0175] In some exemplary embodiments, as shown in Figures 20 and 21, the suspended structure 23 has a plurality of second release holes 232, which can penetrate the suspended structure 23 along a third direction Z. The plurality of second release holes 232 can be arranged around the periphery of the protruding structure 26, for example, they can be evenly arranged. For example, the suspended structure 23 has four second release holes 232, which can be symmetrically designed about a first center line L1 and about a second center line L2. For example, the orthographic projection of the second release hole 232 onto the plane where the composite sensor is located can be L-shaped, or arc-shaped, or S-shaped, etc. In the embodiments of this disclosure, by designing a plurality of second release holes surrounding the protruding structure, the stiffness of the protruding structure can be reduced, and the protruding structure can be prevented from being damaged by external forces during the deformation process of the composite sensor.

[0176] The suspended structure 23 has a plurality of first release holes 231, which can be arranged around the periphery of a plurality of second release holes 232, for example, they can be evenly arranged. In Figure 21, the number of first release holes 231 is simplified.

[0177] In some exemplary embodiments, the first release hole 231 has a first projected area when projected onto the plane where the composite sensor is located, and the second release hole 232 has a second projected area when projected onto the plane where the composite sensor is located. The first projected area is less than the second projected area, or the first projected area is equal to the second projected area, or the first projected area is greater than the second projected area.

[0178] In some exemplary embodiments, as shown in FIG20, the orthographic projection of the connecting beam 24 onto the plane where the composite sensor is located can be rectangular. Each connecting beam 24 includes a first end and a second end disposed opposite to each other along its extension direction. Taking the accelerometer structure layer 20 as an example, which includes four connecting beams 24, namely a first connecting beam 241, a second connecting beam 242, a third connecting beam 243, and a fourth connecting beam 244. The first connecting beam 241 and the third connecting beam 243 are located on both sides of the suspended structure 23 along the first direction X. The second connecting beam 242 and the fourth connecting beam 244 are located on both sides of the suspended structure 23 along the second direction Y.

[0179] Each connecting beam 24 has its first end connected to the suspended structure 23, and its second end is further away from the suspended structure 23 than its first end. For example, the first end of each connecting beam 24 is directly connected to the suspended structure 23. The second end of the first connecting beam 241 has at least one hollow area 240, which penetrates the first connecting beam 241 along the third direction Z. The second end of the third connecting beam 243 has at least one hollow area 240, which penetrates the third connecting beam 243 along the third direction Z. The orthographic projection of the hollow area 240 onto the plane of the composite sensor can be rectangular, circular, or elliptical, etc. In this embodiment, by providing at least one hollow area at the second end of the first connecting beam and at least one hollow area at the second end of the third connecting beam, the sensitivity of the composite sensor to the second direction can be improved, and decoupling from the first direction can be ensured.

[0180] In some exemplary embodiments, as shown in FIG20, the first bridge 2501 and the second bridge 2502 can be an integral structure interconnected with each other. The third bridge 2503 and the fourth bridge 2504 can be an integral structure interconnected with each other.

[0181] In some exemplary embodiments, as shown in FIG20, the fifth bridge 2505 and the sixth bridge 2506 can be an integral structure interconnected with each other. The seventh bridge 2507 and the eighth bridge 2508 can be an integral structure interconnected with each other.

[0182] Figure 23 is an enlarged schematic diagram of the first connecting beam of a composite sensor according to another embodiment of the present disclosure. As shown in Figures 20 and 23, each connecting beam 24 has at least one notch at its first end, and the notch penetrates the connecting beam 24 along the third direction Z. Taking the first connecting beam 241 as an example, the structure of the other connecting beams 24 is the same as that of the first connecting beam 241.

[0183] As shown in Figure 23, each connecting beam 24 includes a first side 24-1 and a second side 24-2 disposed opposite to each other along its width direction. The notch may include at least one first notch 245, which is recessed from one side of the first side 24-1 toward one side of the second side 24-2. The first notch 245 may be a U-shaped notch or a similar U-shaped notch. The notch may include at least one second notch 246, which is recessed from one side of the second side 24-2 toward one side of the first side 24-1. The second notch 246 may be a U-shaped notch or a similar U-shaped notch. For example, each connecting beam 24 has a first notch 245 and a second notch 246 at its first end. Alternatively, each connecting beam 24 may have multiple first notches 245 and multiple second notches 246 at its first end, which may be arranged alternately along the length of the connecting beam 24. The width direction of the connecting beam 24 is parallel to one of the first direction X and the second direction Y, and the length direction of the connecting beam 24 is parallel to the other of the first direction X and the second direction Y. In this embodiment of the present disclosure, by providing at least one notch at the first end of each connecting beam, the detection sensitivity of the composite sensor for the first direction and the second direction can be improved.

[0184] Figure 24A is an enlarged schematic diagram of the ninth bridge of a composite sensor according to another embodiment of the present disclosure. As shown in Figures 24A and 20, each bridge 25 includes at least one varistor connected to it and multiple connecting electrodes. Taking the ninth bridge 2509 as an example, the ninth bridge 2509 may include two varistors and three connecting electrodes. The two varistors are a first varistor 2521 and a second varistor 2522, and the three connecting electrodes are a first connecting electrode 2531, a second connecting electrode 2532, and a third connecting electrode 2533.

[0185] The ninth bridge 2509 is basically the same as the previous embodiment, except that the first connecting electrode 2531 may include a plurality of first sub-segments 2541 extending along the first direction X and a plurality of second sub-segments 2542 extending along the second direction Y. The plurality of first sub-segments 2541 and the plurality of second sub-segments 2542 alternate in sequence and are connected end to end to form a zigzag structure, as shown in the dashed box in FIG24A.

[0186] The second connecting electrode 2532 may include a plurality of first sub-segments 2541 extending along the first direction X and a plurality of second sub-segments 2542 extending along the second direction Y. The plurality of first sub-segments 2541 and the plurality of second sub-segments 2542 alternate sequentially and are connected end to end to form a zigzag structure, as shown in the dashed box in Figure 24A.

[0187] The eleventh bridge 2511 can refer to the ninth bridge 2509. For example, the eleventh bridge 2511 and the ninth bridge 2509 can be designed symmetrically about the second center line L2, which is a straight line that passes through the center of the suspended structure 23 and extends along the second direction Y.

[0188] Figure 24B is an enlarged schematic diagram of the tenth bridge of a composite sensor according to another embodiment of the present disclosure. As shown in Figures 24B and 20, each bridge 25 includes at least one varistor connected to it and multiple connecting electrodes. Taking the tenth bridge 2510 as an example, the tenth bridge 2510 may include a varistor and two connecting electrodes. The varistor is a third varistor 2523, and the two connecting electrodes are a fourth connecting electrode 2534 and a fifth connecting electrode 2535.

[0189] The tenth bridge 2510 is basically the same as the previous embodiment, except that the fourth connecting electrode 2534 may include a plurality of first sub-segments 2541 extending along the first direction X and a plurality of second sub-segments 2542 extending along the second direction Y. The plurality of second sub-segments 2542 and the plurality of first sub-segments 2541 alternate in sequence and are connected end to end to form a zigzag structure, as shown in the dashed box in Figure 24B.

[0190] The fifth connecting electrode 2535 may include a plurality of first sub-segments 2541 extending along the first direction X and a plurality of second sub-segments 2542 extending along the second direction Y. The plurality of second sub-segments 2542 and the plurality of first sub-segments 2541 alternate sequentially and are connected end to end to form a zigzag structure, as shown in the dashed box in Figure 24B.

[0191] The twelfth bridge 2512 can refer to the tenth bridge 2510. For example, the twelfth bridge 2512 and the tenth bridge 2510 can be designed symmetrically about the first center line L1, which is a straight line passing through the center of the suspended structure 23 and extending along the first direction X.

[0192] In this embodiment of the disclosure, by designing the bridge of the third accelerometer to include a U-shaped structure, the stiffness of the bridge of the third accelerometer can be reduced, thereby improving the sensitivity of the composite sensor to third-direction detection.

[0193] Figure 24C is an enlarged schematic diagram of the first bridge of a composite sensor according to another embodiment of the present disclosure. As shown in Figures 24C and 20, each bridge 25 includes at least one varistor and multiple connecting electrodes connected to each other. Taking the first bridge 2501 as an example, the first bridge 2501 may include a varistor and two connecting electrodes. The varistor is a fourth varistor 2524, and the two connecting electrodes are a sixth connecting electrode 2536 and a seventh connecting electrode 2537.

[0194] The orthographic projection of the fourth varistor 2524 onto the plane of the composite sensor can be a rectangle extending along the second direction Y. The orthographic projection of the fourth varistor 2524 onto the plane of the composite sensor can lie within the orthographic projection of the second connecting beam 242 onto the plane of the composite sensor. The fourth varistor 2524 can be located between the sixth connecting electrode 2536 and the seventh connecting electrode 2537, and the sixth connecting electrode 2536 and the seventh connecting electrode 2537 are connected via the fourth varistor 2524.

[0195] The sixth connecting electrode 2536 is located on the side of the fourth varistor 2524 opposite to the second direction Y. The side of the sixth connecting electrode 2536 near the fourth varistor 2524 is in direct contact with the fourth varistor 2524. The orthographic projection of the sixth connecting electrode 2536 onto the plane of the composite sensor lies within the orthographic projection of the second connecting beam 242 onto the plane of the composite sensor. The seventh connecting electrode 2537 is located on the side of the fourth varistor 2524 along the second direction Y. The side of the seventh connecting electrode 2537 near the fourth varistor 2524 is in direct contact with the fourth varistor 2524. A portion of the orthographic projection of the seventh connecting electrode 2537 onto the plane of the composite sensor lies within the orthographic projection of the second connecting beam 242 onto the plane of the composite sensor, and a portion of the orthographic projection of the seventh connecting electrode 2537 onto the plane of the composite sensor lies within the orthographic projection of the substrate 21 onto the plane of the composite sensor. The remaining portion of the seventh connecting electrode 2537 may be located in the first cavity 22.

[0196] The second bridge 2502 and the first bridge 2501 can be designed symmetrically about the second center line L2. The sixth connecting electrode 2536 of the first bridge 2501 and the sixth connecting electrode 2536 of the second bridge 2502 can be an integral structure interconnected. The third bridge 2503 and the first bridge 2501 can be designed symmetrically about the first center line L1. The third bridge 2503 and the fourth bridge 2504 can be designed symmetrically about the second center line L2. The second bridge 2502 to the eighth bridge 2508 can refer to the first bridge 2501, and will not be described in detail further.

[0197] Figure 25 is a cross-sectional schematic diagram of a composite sensor according to another embodiment of this disclosure after the epitaxial layer has been formed. The fabrication method of the composite sensor in this embodiment is basically the same as that in the previous embodiment, the main difference being that, as shown in Figure 25, in forming the sacrificial thin film pattern 40a, the sacrificial thin film pattern 40a has a plurality of vias 40b, and the sacrificial thin film located within the vias 40b is etched away, exposing a portion of the surface of the semiconductor material layer 14. For example, the sacrificial thin film pattern 40a has three vias 40b along the second direction Y, wherein two vias 40b are located on both sides of the second cavity 11b, and the other via 40b is located on one side of the second cavity 11b along the third direction Z. Subsequently, an epitaxial layer 20a is formed based on the vias 40b, and the epitaxial layer 20a located within the other via 40b forms a protrusion structure 26.

[0198] Figure 26 is a cross-sectional schematic diagram of the carrier plate of a composite sensor according to another embodiment of this disclosure. As shown in Figure 26, the structure of the carrier plate 11 is basically the same as that of the previous embodiment, the main difference being that the carrier plate 11 has a plurality of second cavities 11b, which are arranged sequentially at intervals along the second direction Y. All the second cavities 11b are located inside the carrier plate 11. In this embodiment, by providing a plurality of second cavities, the detection range of the pressure sensor can be increased, thus broadening the application range of the composite sensor. During the fabrication process, after the well array pattern is fabricated, annealing is not performed; instead, a sacrificial thin film pattern 40a and an epitaxial layer 20a are formed. Then, the well array pattern is annealed to fabricate the second cavities 11b and the pressure-sensitive film 11a. This facilitates the formation of a thicker pressure-sensitive film, which in turn increases the detection range of the pressure sensor.

[0199] In some possible exemplary embodiments, after forming the sacrificial thin film pattern 40a and the epitaxial layer 20a, a well array pattern is prepared and the well array pattern is annealed to prepare the second cavity 11b and the pressure-sensitive membrane 11a.

[0200] Figure 27 is a cross-sectional schematic diagram of a composite sensor according to another embodiment of the present disclosure. As shown in Figure 27, the accelerometer structure layer 20 and the encapsulation layer 30 are basically the same as those in the previous embodiment. The main difference is that the pressure sensor 10 includes a carrier plate 11 and a plurality of piezoresistive elements 12. The piezoresistive elements 12 can be embedded into the carrier plate 11 from the surface of the carrier plate 11 near the accelerometer structure layer 20, and the surface of the piezoresistive elements 12 near the accelerometer structure layer 20 is exposed by the carrier plate 11.

[0201] The carrier plate 11 includes a pressure-sensitive membrane 11a and a second cavity 11b. The second cavity 11b is located on the side of the pressure-sensitive membrane 11a away from the accelerometer structure layer 20, and is recessed from the side of the carrier plate 11 away from the accelerometer structure layer 20 toward the side closer to the accelerometer structure layer 20. At least a portion of the piezoresistive element 12 can be embedded within the pressure-sensitive membrane 11a from the side of the pressure-sensitive membrane 11a closer to the accelerometer structure layer 20. The conductive structure 50 is in direct contact with the piezoresistive element 12, eliminating the need for a transfer electrode, which simplifies the fabrication process of the pressure sensor and reduces fabrication costs. Furthermore, during fabrication, the sacrificial thin film pattern and epitaxial layer can be formed after the piezoresistive element is formed, and the second cavity can be fabricated after the bonding operation. This facilitates the formation of a thicker pressure-sensitive membrane, which increases the detection range of the pressure sensor. Moreover, the closer proximity of the piezoresistive element to the accelerometer structure layer improves the environmental adaptability of the pressure sensor.

[0202] This disclosure provides a method for fabricating a composite sensor, the composite sensor comprising a pressure sensor and an accelerometer structure layer stacked together; the fabrication method includes:

[0203] A sacrificial film is formed on one side of a semiconductor material layer. The sacrificial film is patterned using a patterning process to form a sacrificial film pattern. The sacrificial film pattern has multiple vias, and the vias expose a portion of the surface of the semiconductor material layer.

[0204] Based on the via, an epitaxial layer is formed on the side of the sacrificial thin film pattern away from the semiconductor material layer using a selective epitaxial process;

[0205] Ion implantation is performed on a portion of the surface of the epitaxial layer away from the semiconductor material layer to form multiple electrical bridges in the accelerometer structure layer, and the multiple electrical bridges constitute at least one of a first Wheatstone bridge, a second Wheatstone bridge, and a third Wheatstone bridge.

[0206] The epitaxial layer is etched from the side of the epitaxial layer away from the semiconductor material layer to form a first cavity of the accelerometer structure layer, and the epitaxial layer forms the substrate, suspended structure and multiple connecting beams of the accelerometer structure layer.

[0207] In some exemplary embodiments, ion implantation is performed on a portion of the surface of the epitaxial layer away from the semiconductor material layer to form multiple bridges of the accelerometer structure layer, including:

[0208] A double-sided ion implantation process is used to implant ions into a portion of the surface of the epitaxial layer away from the semiconductor material layer to form the electrical bridge, and to implant ions into a portion of the surface of the semiconductor material layer away from the epitaxial layer to form the piezoresistive element of the pressure sensor.

[0209] In some exemplary embodiments, before forming a sacrificial film on one side of the semiconductor material layer, the preparation method further includes:

[0210] The semiconductor material layer is etched to form a well array pattern, and the well array pattern includes multiple wells;

[0211] The semiconductor material layer is annealed to form the second cavity and pressure-sensing diaphragm of the pressure sensor, wherein the pressure-sensing diaphragm is farther away from the accelerometer structure layer than the second cavity.

[0212] In some exemplary embodiments, before forming a sacrificial film on one side of the semiconductor material layer, the preparation method further includes:

[0213] The semiconductor material layer is etched to form a well array pattern, and the well array pattern includes multiple wells;

[0214] The preparation method further includes: after forming the epitaxial layer, annealing the semiconductor material layer to form a plurality of second cavities and a pressure-sensing film of the pressure sensor, wherein the pressure-sensing film is farther away from the accelerometer structure layer than the plurality of second cavities.

[0215] In some exemplary embodiments, patterning the sacrificial film to form a sacrificial film pattern using a patterning process includes: the sacrificial film pattern having three through holes, and the three through holes being arranged sequentially along a direction parallel to the plane of the composite sensor;

[0216] The epitaxial layer formed based on the via includes: the epitaxial layer located within the central via forms a protruding structure of the accelerometer structure layer.

[0217] While the embodiments disclosed in this invention have been described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. It should be noted that the above embodiments or implementation methods are merely exemplary and not restrictive. Therefore, this disclosure is not limited to the content specifically shown and described herein. Various modifications, substitutions, or omissions can be made to the form and details of the implementation without departing from the scope of this disclosure.

Claims

1. A composite sensor, comprising: Pressure sensor; An accelerometer structure layer is stacked on top of the pressure sensor; The accelerometer structure layer includes a substrate and a first cavity disposed in the substrate, wherein the first cavity penetrates the substrate in a direction perpendicular to the plane of the composite sensor; the accelerometer structure layer also includes a suspended structure, a plurality of connecting beams, and a plurality of electrical bridges, wherein the plurality of electrical bridges constitute at least one of a first Wheatstone bridge, a second Wheatstone bridge, and a third Wheatstone bridge; the suspended structure is located within the first cavity, the plurality of connecting beams are arranged around the suspended structure, and the suspended structure is connected to the substrate via the plurality of connecting beams; a portion of the electrical bridge is embedded in the substrate from the surface of the substrate away from the pressure sensor.

2. The composite sensor as described in claim 1, wherein, Each of the bridge circuits includes at least one varistor, the orthographic projection of which lies within the orthographic projection of the suspended structure onto the plane of the composite sensor, or the orthographic projection of which lies within the orthographic projection of the connecting beam onto the plane of the composite sensor.

3. The composite sensor as described in claim 1 or 2, wherein, The plurality of connecting beams includes a first connecting beam, a second connecting beam, a third connecting beam, and a fourth connecting beam; the first connecting beam and the third connecting beam are located on both sides of the suspended structure along a first direction, and the second connecting beam and the fourth connecting beam are located on both sides of the suspended structure along a second direction; the first direction and the second direction intersect and the plane formed thereby is parallel to the plane where the composite sensor is located.

4. The composite sensor as described in claim 3, wherein, The plurality of bridges includes a first bridge, a second bridge, a third bridge, and a fourth bridge, and the first bridge, the second bridge, the third bridge, and the fourth bridge constitute the first Wheatstone bridge; the first bridge, the second bridge, and the second connecting beam are arranged in a group, and the orthographic projections of the varistor of the first bridge and the varistor of the second bridge on the plane where the composite sensor is located are both located within the orthographic projection of the second connecting beam on the plane where the composite sensor is located; The third bridge, the fourth bridge, and the fourth connecting beam are arranged in a group. The orthographic projections of the varistor of the third bridge and the varistor of the fourth bridge onto the plane where the composite sensor is located are both located within the orthographic projection of the fourth connecting beam onto the plane where the composite sensor is located.

5. The composite sensor as described in claim 3 or 4, wherein, The plurality of bridges includes a fifth bridge, a sixth bridge, a seventh bridge, and an eighth bridge, and the fifth bridge, the sixth bridge, the seventh bridge, and the eighth bridge constitute the second Wheatstone bridge; the fifth bridge, the sixth bridge, and the first connecting beam are arranged in a group, and the orthographic projections of the varistor of the fifth bridge and the varistor of the sixth bridge on the plane where the composite sensor is located are both located within the orthographic projection of the first connecting beam on the plane where the composite sensor is located; The seventh bridge, the eighth bridge, and the third connecting beam are arranged in a group. The orthographic projections of the varistor of the seventh bridge and the varistor of the eighth bridge on the plane where the composite sensor is located are both located within the orthographic projection of the third connecting beam on the plane where the composite sensor is located.

6. The composite sensor as described in claim 5, wherein, Each of the connecting beams includes a first end and a second end disposed opposite to each other. The first end is connected to the suspended structure, and the second end is connected to the substrate. The second end of the first connecting beam is provided with at least one hollow area, and the hollow area penetrates the first connecting beam in a direction perpendicular to the plane where the composite sensor is located. The second end of the third connecting beam is provided with at least one hollow area, and the hollow area penetrates the third connecting beam in a direction perpendicular to the plane where the composite sensor is located.

7. The composite sensor according to any one of claims 3 to 6, wherein, The plurality of bridges includes a ninth bridge, a tenth bridge, an eleventh bridge, and a twelfth bridge, and the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge constitute the third Wheatstone bridge; the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge are respectively arranged in a one-to-one correspondence with the first connecting beam, the second connecting beam, the third connecting beam, and the fourth connecting beam, respectively. The bridge constituting the third Wheatstone bridge surrounds at least a portion of the corresponding connecting beam, and the orthographic projection of the bridge constituting the third Wheatstone bridge onto the plane of the composite sensor does not overlap with the orthographic projection of the corresponding connecting beam onto the plane of the composite sensor. The orthographic projection of the varistor constituting the third Wheatstone bridge onto the plane of the composite sensor is located within the orthographic projection of the suspended structure onto the plane of the composite sensor.

8. The composite sensor as described in claim 3, wherein, The plurality of bridges includes a ninth bridge, a tenth bridge, an eleventh bridge, and a twelfth bridge, and the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge constitute the third Wheatstone bridge; the ninth bridge, the tenth bridge, the eleventh bridge, and the twelfth bridge are respectively arranged in a one-to-one correspondence with the first connecting beam, the second connecting beam, the third connecting beam, and the fourth connecting beam, respectively, and the orthographic projection of the bridge constituting the third Wheatstone bridge on the plane of the composite sensor overlaps with the orthographic projection of the corresponding connecting beam on the plane of the composite sensor, and the orthographic projection of the varistor constituting the third Wheatstone bridge on the plane of the composite sensor is located within the orthographic projection of the suspended structure on the plane of the composite sensor.

9. The composite sensor according to any one of claims 1 to 8, wherein, Each of the connecting beams includes a first end and a second end disposed opposite to each other, the first end being connected to the suspended structure and the second end being connected to the substrate; at least one of the connecting beams has at least one notch at its first end, and the notch penetrates the connecting beam in a direction perpendicular to the plane of the composite sensor.

10. The composite sensor as described in claim 9, wherein, Each of the connecting beams includes a first side and a second side disposed opposite to each other along its width direction. At least one of the connecting beams has at least one first notch and at least one second notch at its first end. The first notch is recessed from one side of the first side toward one side of the second side, and the second notch is recessed from one side of the second side toward one side of the first side. The width direction is parallel to the plane where the composite sensor is located.

11. The composite sensor according to any one of claims 1 to 10, wherein, The accelerometer structure layer also includes a protruding structure, which is located on the side of the suspended structure near the pressure sensor and is connected to the suspended structure. The orthographic projection of the protruding structure onto the plane of the composite sensor is within the orthographic projection of the suspended structure onto the plane of the composite sensor.

12. The composite sensor as described in claim 11, wherein, The suspended structure has multiple first release holes and multiple second release holes, the multiple second release holes being arranged around the protruding structure, and the multiple first release holes being arranged around the periphery of the multiple second release holes.

13. The composite sensor according to any one of claims 1 to 12, wherein, The pressure sensor includes a carrier plate, the carrier plate includes a pressure-sensing diaphragm and a second cavity, the second cavity is located on the side of the pressure-sensing diaphragm near the accelerometer structural layer, and the second cavity is located inside the carrier plate.

14. The composite sensor as described in claim 13, wherein, Multiple second cavities are arranged sequentially at intervals along a direction parallel to the plane where the composite sensor is located.

15. The composite sensor according to any one of claims 1 to 12, wherein, The pressure sensor includes a carrier plate, the carrier plate includes a pressure-sensing diaphragm and a second cavity, the second cavity is located on the side of the pressure-sensing diaphragm away from the accelerometer structure layer, and the second cavity is recessed from the side of the carrier plate away from the accelerometer structure layer toward the direction closer to the accelerometer structure layer.

16. A method for fabricating a composite sensor, the composite sensor comprising a pressure sensor and an accelerometer structural layer stacked together; the fabrication method comprising: A sacrificial film is formed on one side of a semiconductor material layer. The sacrificial film is patterned using a patterning process to form a sacrificial film pattern. The sacrificial film pattern has multiple vias, and the vias expose a portion of the surface of the semiconductor material layer. Based on the via, an epitaxial layer is formed on the side of the sacrificial thin film pattern away from the semiconductor material layer using a selective epitaxial process; Ion implantation is performed on a portion of the surface of the epitaxial layer away from the semiconductor material layer to form multiple electrical bridges in the accelerometer structure layer, and the multiple electrical bridges constitute at least one of a first Wheatstone bridge, a second Wheatstone bridge, and a third Wheatstone bridge. The epitaxial layer is etched from the side of the epitaxial layer away from the semiconductor material layer to form a first cavity of the accelerometer structure layer, and the epitaxial layer forms the substrate, suspended structure and multiple connecting beams of the accelerometer structure layer.

17. The method for fabricating the composite sensor as described in claim 16, wherein, Ion implantation is performed on a portion of the surface of the epitaxial layer away from the semiconductor material layer to form multiple bridges of the accelerometer structure layer, including: A double-sided ion implantation process is used to implant ions into a portion of the surface of the epitaxial layer away from the semiconductor material layer to form the electrical bridge, and to implant ions into a portion of the surface of the semiconductor material layer away from the epitaxial layer to form the piezoresistive element of the pressure sensor.

18. The method for fabricating the composite sensor as described in claim 16 or 17, wherein before forming a sacrificial film on one side of the semiconductor material layer, the fabrication method further comprises: The semiconductor material layer is etched to form a well array pattern, and the well array pattern includes multiple wells; The semiconductor material layer is annealed to form the second cavity and pressure-sensing diaphragm of the pressure sensor, wherein the pressure-sensing diaphragm is farther away from the accelerometer structure layer than the second cavity.

19. The method for fabricating the composite sensor as described in claim 16 or 17, wherein before forming a sacrificial thin film on one side of the semiconductor material layer, the fabrication method further comprises: The semiconductor material layer is etched to form a well array pattern, and the well array pattern includes multiple wells; The preparation method further includes: after forming the epitaxial layer, annealing the semiconductor material layer to form a plurality of second cavities and a pressure-sensing film of the pressure sensor, wherein the pressure-sensing film is farther away from the accelerometer structure layer than the plurality of second cavities.

20. The method for fabricating the composite sensor according to any one of claims 16 to 19, wherein, The patterning process for the sacrificial film to form a sacrificial film pattern includes: the sacrificial film pattern having three through holes, and the three through holes being arranged sequentially along a direction parallel to the plane of the composite sensor; The epitaxial layer formed based on the via includes: the epitaxial layer located within the central via forms a protruding structure of the accelerometer structure layer.

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