CN117246972B - Micro-electromechanical force sensor and preparation method thereof - Google Patents

Micro-electromechanical force sensor and preparation method thereof Download PDF

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Publication number
CN117246972B
CN117246972B CN202311536483.2A CN202311536483A CN117246972B CN 117246972 B CN117246972 B CN 117246972B CN 202311536483 A CN202311536483 A CN 202311536483A CN 117246972 B CN117246972 B CN 117246972B
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substrate
dielectric layer
layer
forming
pressure sensor
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CN117246972A (en
Inventor
吕萍
李刚
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Memsensing Microsystems Suzhou China Co Ltd
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Memsensing Microsystems Suzhou China Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
    • B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/0009—Structural features, others than packages, for protecting a device against environmental influences
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C3/00—Assembling of devices or systems from individually processed components
    • B81C3/001—Bonding of two components
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/02—Sensors
    • B81B2201/0264—Pressure sensors

Abstract

The application provides a microcomputer voltage sensor and a preparation method thereof. A microelectromechanical pressure sensor, comprising: a first substrate; a pressure sensitive component located on one side of the first substrate; the pressure sensitive response component comprises a piezoresistor; the first dielectric layer is positioned on one side of the pressure sensitive response component, which is far away from the first substrate; a cavity is arranged in the first dielectric layer and penetrates through the first dielectric layer; the front projection of the cavity on the first substrate covers the front projection of the piezoresistor on the first substrate; and the second substrate, the first dielectric layer and one side of the second substrate facing the first substrate are bonded. According to the method, the first dielectric layer is formed on the first substrate, the cavity is formed in the first dielectric layer, the height consistency of the cavity is good, the limit consistency is good, the first dielectric layer is connected with the second substrate in a bonding mode, and the method has the advantages of being small in packaging size, simple in manufacturing procedure and the like.

Description

Micro-electromechanical force sensor and preparation method thereof
Technical Field
The application relates to the field of sensors, in particular to a microcomputer voltage sensor and a preparation method thereof.
Background
Consumer electronics such as toys, cell phones, tablets, headphones, and the like are currently increasingly developing towards intelligence, in which more and more sensors are added to be able to sense more physical quantities. Among them, there is also an increasing demand for measurement of stress or pressure generated by contact with a human body, particularly a finger or the like.
Existing force sensor principles based on Micro-Electro-Mechanical System (MEMS) technology are piezoresistive and capacitive, where piezoresistive is usually implemented in three ways: 1) And (3) metal eutectic bonding. For example, a silicon wafer with MEMS patterns and a wafer serving as a silicon cap are subjected to metal eutectic bonding, and then wire bonding and encapsulation are performed. However, this eutectic bonding requires expensive equipment and is costly. 2) Silicon-silicon bonding and CSP (Chip Size Package) packaging and solder ball formation. For example, a silicon wafer with MEMS patterns and a silicon wafer for pressing are subjected to silicon-silicon bonding, and thinned and CSP packaged. Although the chip size can be small, the manufacturing process is complex and costly. 3) The piezoresistive chip forms a stainless steel ball with rolling function as a pressed component in the packaging process, and the chip has more complex packaging and more working procedures although the manufacturing process is more conventional.
In view of the foregoing, there is a need for providing a microelectromechanical pressure sensor and a method for manufacturing the same, which solves the problems of the existing microelectromechanical pressure sensor that the package size is too large and the manufacturing process is complex.
Disclosure of Invention
The invention aims to: the purpose of the application is to provide a microcomputer voltage force sensor, which has the advantages of small packaging size, simple manufacturing process and the like. Another object of the present application is to provide a method for manufacturing a microelectromechanical pressure sensor, which has advantages of small package size and simple manufacturing process.
The technical scheme is as follows: to achieve the above object, the present application provides a microelectromechanical pressure sensor, comprising:
a first substrate;
a pressure sensitive component located on one side of the first substrate; the pressure sensitive response component comprises a piezoresistor;
a first dielectric layer located on a side of the pressure sensitive response component remote from the first substrate; a cavity is arranged in the first dielectric layer and penetrates through the first dielectric layer; the orthographic projection of the cavity on the first substrate covers the orthographic projection of the piezoresistor on the first substrate;
and the first dielectric layer is bonded with one side of the second substrate facing the first substrate.
In some embodiments, the microelectromechanical pressure sensor further comprises:
the second dielectric layer is positioned between the first substrate and the first dielectric layer;
and the first via hole penetrates through the second dielectric layer.
In some embodiments, the microelectromechanical pressure sensor further comprises:
the wiring is positioned on one side surface of at least part of the second dielectric layer, which is far away from the first substrate, and in the first via hole;
the pressure sensitive response assembly further includes a lead: the lead is electrically connected with the piezoresistor; the trace is electrically connected with the lead through the first via hole.
In some embodiments, the microelectromechanical pressure sensor further comprises:
the second via hole penetrates through the second substrate and the first dielectric layer;
and the metal layer is positioned on one side surface of at least part of the second substrate far away from the first dielectric layer and in the second via hole, and is electrically connected with the wiring through the second via hole.
In some embodiments, the microelectromechanical pressure sensor further comprises:
an oxide layer located between the second substrate and the metal layer, and between the sidewall of the second via and the metal layer;
and the passivation layer is positioned on one side surface of the metal layer away from the second substrate.
In some embodiments, the microelectromechanical pressure sensor further comprises:
a third via penetrating the passivation layer;
the bonding layer is positioned in the third via hole, and the bonding layer is electrically connected with the metal layer through the third via hole;
and the solder ball is positioned on one side of the bonding layer away from the metal layer, and is electrically connected with the bonding layer.
In some embodiments, the microelectromechanical pressure sensor further comprises:
a force bearing portion disposed on a side of the first substrate remote from the first dielectric layer;
the circuit board is electrically connected with the solder balls;
and the plastic packaging part is positioned at one side of the circuit board facing the force bearing part.
In some embodiments, an orthographic projection of the force bearing portion on the first substrate at least partially overlaps an orthographic projection of the cavity on the first substrate.
In some embodiments, the second dielectric layer includes a first sub-dielectric layer and a second sub-dielectric layer that are stacked, the first sub-dielectric layer being located on a side proximate to the first substrate.
In some embodiments, the cavity has a height H along a thickness direction of the first substrate, and the first dielectric layer has a first thickness M that satisfies: h is less than or equal to M.
Correspondingly, the application also provides a preparation method of the micro-electromechanical force sensor, which comprises the following steps:
providing a first substrate;
providing a pressure sensitive component located on one side of the first substrate, the pressure sensitive component comprising a piezo-resistor;
forming a first dielectric layer, wherein the first dielectric layer is positioned on one side of the pressure sensitive response component, which is far away from the first substrate;
forming a cavity, wherein the cavity penetrates through the first dielectric layer, and the orthographic projection of the cavity on the first substrate covers the orthographic projection of the piezoresistor on the first substrate;
providing a second substrate;
and bonding the second substrate and the first substrate, and attaching the first dielectric layer and the second substrate to one side of the first substrate.
In some embodiments, after the step of providing the pressure sensitive response element, further comprising:
forming a second dielectric layer, wherein the second dielectric layer is positioned between the first substrate and the first dielectric layer;
and forming a first via hole, wherein the first via hole penetrates through the second dielectric layer.
In some embodiments, after the step of forming the first via, further comprising:
forming a wiring, wherein the wiring is positioned on one side surface of at least part of the second dielectric layer, which is far away from the first substrate, and in the first via hole;
the pressure sensitive response assembly further includes a lead: the lead is electrically connected with the piezoresistor; the trace is electrically connected with the lead through the first via hole.
In some embodiments, after bonding the second substrate to the first substrate, further comprising:
forming a second via hole, wherein the second via hole penetrates through the second substrate and the first dielectric layer;
and forming a metal layer, wherein at least part of the metal layer is positioned on one side surface of the second substrate far away from the first dielectric layer, and in the second via hole, the metal layer is electrically connected with the wiring through the second via hole.
In some embodiments, after forming the second via, further comprising:
forming an oxide layer, wherein the oxide layer is positioned between the second substrate and the metal layer and between the side wall of the second via hole and the metal layer;
and forming a passivation layer, wherein the passivation layer is positioned on one side surface of the metal layer, which is far away from the second substrate.
In some embodiments, after forming the passivation layer, further comprising:
forming a third via hole, wherein the third via hole penetrates through the passivation layer;
forming a bonding layer, wherein the bonding layer is positioned in the third via hole, and the bonding layer is electrically connected with the metal layer through the third via hole;
and forming a solder ball, wherein the solder ball is positioned on one side of the bonding layer away from the metal layer, and the solder ball is electrically connected with the bonding layer.
In some embodiments, after forming the solder balls, further comprising:
a force bearing portion is formed on a side of the first substrate remote from the first dielectric layer.
In some embodiments, prior to forming the force bearing portion, further comprising:
the first substrate is thinned.
In some embodiments, after forming the solder balls, further comprising:
providing a circuit board;
and electrically connecting the solder balls with the circuit board.
In some embodiments, after electrically connecting the solder balls with the circuit board, further comprising:
and forming a plastic package part, wherein the plastic package part is positioned on one side of the circuit board, which faces the force bearing part.
In some embodiments, after bonding the second substrate to the first substrate, further comprising:
and thinning the second substrate.
According to the method, the cavity is formed in the first dielectric layer, the height consistency of the cavity is good, the limit consistency is good, and the first dielectric layer is bonded and connected with the second substrate, so that the method has the advantages of being low in bonding cost, simple in manufacturing procedure and the like. Further, by forming the cavity in the first dielectric layer, the device provides a space for deformation of the pressure sensitive film under the action of tiny stress, and by controlling the height H of the cavity to be smaller than or equal to the first thickness M of the first dielectric layer, the limiting effect of the cavity on the pressure sensitive film is good, and the reliability of the device is improved. Further, through carrying out the trompil in the second dielectric layer, trompil in second substrate and the first dielectric layer, and trompil in the passivation layer, realize the transmission and the detection of pressure sensitive response subassembly signal of telecommunication, realized the encapsulation of device wafer level, encapsulation simple process. Further, by thinning the first substrate prior to forming the force-bearing portion, the thickness of the device is reduced, thereby reducing the thickness of the device package. In addition, by thinning the first substrate and the second substrate, the thickness of the device is reduced, and the packaging thickness of the device is further reduced. Further, the device size can be reduced by using solder balls as the terminals of the pressure sensitive component. According to the plastic packaging part, external water vapor can be prevented from entering the device, so that the reliability and the service life of the device are improved.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a first configuration of a MEMS sensor provided herein;
FIG. 2 is a schematic diagram of a second configuration of the MEMS sensor provided herein;
FIG. 3 is a schematic diagram of a first arrangement of solder balls in a MEMS sensor provided herein;
FIG. 4 is a schematic diagram of a second arrangement of solder balls in the MEMS sensor provided herein;
FIG. 5 is a flow chart of a method of manufacturing a microelectromechanical pressure sensor provided herein;
FIG. 6 is a schematic diagram of a first step in a method for manufacturing a MEMS sensor according to the present disclosure;
FIG. 7 is a schematic diagram of a second step in the method for manufacturing a MEMS sensor according to the present disclosure;
FIG. 8 is a schematic structural diagram of a third step in the method for manufacturing a MEMS sensor according to the present disclosure;
FIG. 9 is a schematic diagram of a fourth step in the method for manufacturing a MEMS sensor according to the present disclosure;
fig. 10 is a schematic structural diagram of a fifth step in the method for manufacturing a microelectromechanical pressure sensor provided in the present application.
In the drawings, the components represented by the respective reference numerals are as follows:
10. a first substrate; 11. a pressure sensitive response component; 111. a piezoresistor; 112. a lead wire; 12. a first dielectric layer; 121. a cavity; 131. a first sub-dielectric layer; 132. a second sub-dielectric layer; 14. a first via; 15. routing; 20. a second substrate; 21. a second via; 22. a metal layer; 23. an oxide layer; 24. a passivation layer; 241. a third via; 25. a bonding layer; 26. solder balls; 30. a force bearing part; 40. a circuit board; 50. and a plastic package part.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
The terms "first," "second," "third," "fourth," and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms of directions such as up, down, left, and right are referred to in this application only with reference to the attached drawings. Therefore, the use of numerical, directional and positional relationship terms is intended to illustrate and understand the present application, and is not intended to limit the present application. In the drawings, like structural elements are denoted by like reference numerals.
The embodiment of the application provides a microcomputer voltage sensor and a preparation method thereof, and the application is described in detail below with reference to specific embodiments.
Referring to fig. 1-4 and 6-10, a microelectromechanical pressure sensor includes a first substrate 10, a pressure sensitive element 11, a first dielectric layer 12, a cavity 121, and a second substrate 20; the pressure sensitive response element 11 is located on one side of the first substrate 10; the pressure sensitive response assembly 11 comprises a piezo-resistor 111; the first dielectric layer 12 is positioned on one side of the pressure sensitive response component 11 far away from the first substrate 10, a cavity 121 is arranged in the first dielectric layer 12, and the cavity 121 penetrates through the first dielectric layer 12; the front projection of the cavity 121 onto the first substrate 10 covers the front projection of the piezo-resistor 111 onto the first substrate 10; the first dielectric layer 12 is bonded to a side of the second substrate 20 facing the first substrate 10.
Wherein the first substrate 10 may be n-type silicon. The material of the first dielectric layer 12 may be silicon oxide. The material of the first dielectric layer 12 may be ethyl silicate (Tetraethyl Orthosilicate, TEOS), and the cavity 121 penetrates through the first dielectric layer 12, so that the height of the cavity 121 is determined by the thickness of the first dielectric layer 12, and the cavity 121 can provide a deformation space and limit the deformation area. Therefore, the cavity 121 is formed with high height uniformity and good spacing uniformity. The membrane layer of the cavity 121 facing the first substrate 10 is a pressure sensitive membrane. The length and width of the cavity 121 thus determines the length and width of the pressure sensitive membrane. The second substrate 20 may be a silicon substrate, and the second substrate 20 may be fusion bonded to the first substrate 10. Because the thermal expansion coefficients of the substrate materials are close, the thermal stress mismatch can be reduced by adopting a fusion bonding mode; the semiconductor-based semiconductor process is more compatible with IC process, and can be used for etching, depositing films and the like, and the critical dimension is small.
In some embodiments, the microelectromechanical pressure sensor further comprises a second dielectric layer 13 and a first via 14, the second dielectric layer 13 being located between the first substrate 10 and the first dielectric layer 12; the first via 14 penetrates the second dielectric layer 13. It will be appreciated that by forming the first via 14 through the second dielectric layer 13, the electrical signal of the pressure sensitive transducer assembly 11 is transmitted through the first via 14.
In some embodiments, the second dielectric layer 13 includes a first sub-dielectric layer 131 and a second sub-dielectric layer 132 that are stacked, and the first sub-dielectric layer 131 is located on a side close to the first substrate 10. Specifically, the material of the first sub-dielectric layer 131 may be silicon oxide, and the first sub-dielectric layer 131 covers the pressure sensitive element 11, so that the pressure sensitive element 11 can be protected, and the scratch resistance of the first substrate 10 is improved. The second sub-dielectric layer 132 may be a single dielectric layer, such as a silicon oxide layer or a silicon nitride layer, or may be a composite dielectric layer, such as a silicon oxide-silicon nitride composite layer, or a silicon oxide-silicon nitride-silicon oxide composite layer.
In some embodiments, the first sub-dielectric layer 131 has a second thickness L along the thickness direction X, satisfying: l is more than or equal to 30nm and less than or equal to 500nm. In particular, the second thickness L may be in a range consisting of one or both of 30nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, and the above-mentioned values of the second thickness L are given by way of example only, as long as they are within the range of 30 nm.ltoreq.L.ltoreq.500 nm, all within the scope of protection of the present application. By controlling the second thickness L within this range, the scratch resistance of the first substrate 10 can be improved without increasing the thickness of the microelectromechanical pressure sensor.
In some embodiments, the second sub-dielectric layer 132 has a third thickness N along the thickness direction X, satisfying: n is more than or equal to 400nm and less than or equal to 1000nm. In particular, the third thickness N may be in the range of one or both of 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, the above values of the third thickness N being given by way of example only, as long as within the range of 400 nm.ltoreq.N.ltoreq.1000 nm, all being within the scope of protection of the present application. The scratch resistance of the first substrate 10 can be further improved without increasing the thickness of the microelectromechanical pressure sensor by controlling the third thickness N within this range.
In some embodiments, the microelectromechanical pressure sensor further includes a trace 15, where the trace 15 is located on a side of at least a portion of the second dielectric layer 13 away from the first substrate 10, and within the first via 14; the pressure sensitive response assembly 11 further comprises a lead 112: the lead 112 is electrically connected with the piezoresistor 111; the trace 15 is electrically connected to the lead 112 through the first via 14. Specifically, the material of the trace 15 includes one or more of aluminum, aluminum copper, aluminum silicon copper, gold, and platinum. Specifically, the varistor 111 is formed by lightly doping at least a partial region of the first substrate 10 with boron; the first lead 112 is formed by heavily doping at least a partial region of the first substrate 10 with boron.
It will be appreciated that by forming the trace 15 in a side of the second dielectric layer 13 remote from the first substrate 10 and in the first via 14, an electrical signal of the pressure sensitive element 11 is transmitted by the trace 15 through the trace 15.
In some embodiments, the microelectromechanical pressure sensor further includes a second via 21 and a metal layer 22, the second via 21 extending through the second substrate 20 and the first dielectric layer 12; the metal layer 22 is located on at least a portion of a side of the second substrate 20 away from the first dielectric layer 12 and in the second via 21, and the metal layer 22 is electrically connected to the trace 15 through the second via 21. The metal layer 22 is a redistribution layer (Re-Distribution Layer, RDL) copper.
It will be appreciated that by forming the metal layer 22 on at least a portion of a side of the second substrate 20 remote from the first dielectric layer 12 and within the second via 21, the metal layer 22 is electrically connected to the trace 15 through the second via 21 so that the electrical signal of the pressure sensitive element 11 is transmitted by the trace 15 and the metal layer 22.
In some embodiments, the microelectromechanical pressure sensor further comprises an oxide layer 23 and a passivation layer 24, the oxide layer 23 being located between the second substrate 20 and the metal layer 22, and between the sidewalls of the second via 21 and the metal layer 22; passivation layer 24 is located on a side of metal layer 22 remote from second substrate 20. Specifically, the material of the oxide layer 23 may be silicon nitride or silicon oxide. The passivation layer 24 is made of Polyimide (PI).
It will be appreciated that by forming the oxide layer 23 between the second substrate 20 and the metal layer 22, the adhesion of the metal layer 22 may be improved, thereby improving the stability of the electrical connection between the metal layer 22 and the trace 15, and ultimately improving the stability of the microelectromechanical pressure sensor. By forming the passivation layer 24 on the side of the metal layer 22 remote from the second substrate 20, the metal layer 22 and the oxide layer 23 can be protected, and scratch resistance thereof can be improved.
In some embodiments, the microelectromechanical pressure sensor further includes a third via 241, a bonding layer 25, and a solder ball 26, the third via 241 extending through the passivation layer 24; the bonding layer 25 is located in the third via 241, and the bonding layer 25 and the metal layer 22 are electrically connected through the third via 241; the solder balls 26 are located on the side of the bonding layer 25 remote from the metal layer 22. Specifically, the bonding layer 25 is an Under Bump Metallization (UBM); wherein the bonding layer 25 may electrically connect the solder balls 26 with the metal layer 22; the bonding layer 25 may also block diffusion of material atoms of the solder balls 26 into the metal layer 22; the bonding layer 25 may also adhere the dielectric layer and the traces 15 and block contaminants from migrating to the traces 15 in the horizontal direction of the dielectric layer.
In some embodiments, the orthographic projection of the cavity 121 at least partially overlaps the orthographic projection of the solder ball 26 along the thickness direction X of the first substrate 10; alternatively, the front projection of cavity 121 is separated from the front projection of solder ball 26.
Wherein the solder ball 26 material includes one or more of AuSn, ni, sn, ag. The location of the solder balls 26 may be determined according to requirements and chip size. Typically, the mems force sensor comprises four piezoresistive wheatstone bridges, i.e. 4 signal output structures, so that the number of solder balls 26 is typically 4, and the balls are symmetrically arranged, as shown in fig. 3, where the front projection of the cavity 121 at least partially overlaps or is separated from the front projection of the solder balls 26. The number of solder balls 26 may be 5, one of the solder balls 26 is placed at the center, and the solder balls 26 at the center are no-signal solder balls 26, as shown in fig. 4, at least a part of the orthographic projection of the cavity 121 and the orthographic projection of the solder balls 26 overlap, and the solder balls 26 at the center have a supporting effect on the device, so that the stress of the device is more uniform, and the stability of the device is further improved.
In some embodiments, the microelectromechanical pressure sensor further includes a force-bearing portion 30, a circuit board 40, and a plastic package 50, the force-bearing portion 30 being disposed on a side of the first substrate 10 remote from the first dielectric layer 12; the wiring board 40 is electrically connected to the solder balls 26; the plastic package 50 is located on a side of the circuit board 40 facing the force bearing portion 30. Specifically, the force-bearing portion 30 may be formed by etching the first substrate 10, and the force-bearing portion 30 may be a convex portion located on a side of the first substrate 10 facing away from the second substrate 20; specifically, the force bearing portion 30 may be a spacer attached to the first substrate 10. For example, the metal pad may be made of stainless steel or Ni alloy. The force bearing part 30 is hemispherical or hat-shaped, so that on one hand, the touch and pressing can be facilitated, and on the other hand, the external pressure or the pressure intensity can be uniformly dispersed to act on the stress sensitive area of the pressure sensitive component 11, so that the stress is uniform. When a force acts on the force bearing portion 30, the region of the plurality of piezoresistors 111 located right above the cavity 121 will deform, and eventually will output sensitivity, and finally output to the signal processing circuit on the circuit board 40 through the lead 112, the trace 15 and the metal layer 22 through the solder ball 26 for signal processing. Therefore, the magnitude of the external force can be known by monitoring the output of the signal. Specifically, the wiring board 40 may be a printed circuit board, a flexible printed circuit board, or a ceramic substrate; the solder balls 26 are electrically connected to pads on the wiring board 40. Specifically, the plastic package 50 may be formed by an injection molding process, and the plastic package 50 is a package structure of the mems sensor. The molding part 50 is made of an insulating material including, but not limited to, an organic or inorganic substance, for example, silicon, glass, epoxy, silicone, epoxy fiberglass cloth, etc. The plastic package 50 is used for protecting the microcomputer voltage sensor, and can prevent external water vapor from entering the device, so that the reliability and the service life of the device are improved.
In some embodiments, the orthographic projection of the force bearing portion 30 onto the first substrate 10 at least partially overlaps with the orthographic projection of the cavity 121 onto the first substrate 10.
It will be appreciated that the force-bearing portion 30 may be located directly above the cavity 121, or that the force-bearing portion 30 may be disposed overlapping a partial region of the cavity 121. By controlling the front projection of the force-bearing part 30 to at least partially overlap with the front projection of the cavity 121, when a force acts on the force-bearing part 30, the region of the plurality of piezoresistors 111 directly above the cavity 121 will deform, and finally a sensitivity output will be generated.
In some embodiments, along the thickness direction X of the first substrate 10, the cavity 121 has a height H and the first dielectric layer 12 has a first thickness M, satisfying: h is less than or equal to M.
It will be appreciated that the cavity 121 may provide room for deformation, and that the height H of the cavity 121 is determined by the first thickness M of the first dielectric layer 12, while the first dielectric layer 12 may also limit the deformation area. Therefore, the cavity 121 is formed with high height uniformity and good spacing uniformity.
In some embodiments, the first dielectric layer 12 has a first thickness M that satisfies: m is more than or equal to 1000nm and less than or equal to 3000nm. In particular, the first thickness M may be in the range of one or both of 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, the above values of the first thickness M being given by way of example only, as long as within the range 1000 nm.ltoreq.M.ltoreq.3000 nm, all being within the scope of protection of the present application. The first thickness M is controlled within the range, so that the height of the cavity 121 can be limited, and the high consistency and the good limit consistency of the cavity 121 are realized.
As shown in fig. 1 to 10, correspondingly, the present application further provides a method for preparing a microelectromechanical pressure sensor, including:
step S1: providing a first substrate 10;
step S2: providing a pressure sensitive component 11, the pressure sensitive component 11 being located on one side of the first substrate 10, the pressure sensitive component 11 comprising a piezo-resistor 111;
step S3: forming a first dielectric layer 12, wherein the first dielectric layer 12 is positioned on one side of the pressure sensitive response component 11 away from the first substrate 10;
step S4: forming a cavity 121, wherein the cavity 121 penetrates through the first dielectric layer 12, and the orthographic projection of the cavity 121 on the first substrate 10 covers the orthographic projection of the piezoresistor 111 on the first substrate 10;
step S5: providing a second substrate 20;
step S6: the second substrate 20 is bonded to the first substrate 10, and the first dielectric layer 12 is bonded to the second substrate 20 on the side facing the first substrate 10.
Wherein the first substrate 10 may be n-type silicon. The material of the first dielectric layer 12 may be silicon oxide. The material of the first dielectric layer 12 may be ethyl silicate (Tetraethyl Orthosilicate, TEOS), and the cavity 121 penetrates through the first dielectric layer 12, so that the height of the cavity 121 is determined by the thickness of the first dielectric layer 12, and the cavity 121 can provide a deformation space and limit the deformation area. Therefore, the cavity 121 is formed with high height uniformity and good spacing uniformity. The membrane layer of the cavity 121 facing the first substrate 10 is a pressure sensitive membrane. The length and width of the cavity 121 thus determines the length and width of the pressure sensitive membrane. The second substrate 20 may be a silicon substrate, and the second substrate 20 may be fusion bonded to the first substrate 10. Because the thermal expansion coefficients of the substrate materials are close, the thermal stress mismatch can be reduced by adopting a fusion bonding mode; the semiconductor-based semiconductor process is more compatible with IC process, and can be used for etching, depositing films and the like, and the critical dimension is small.
As shown in fig. 6, in some embodiments, after the step of providing the pressure sensitive response assembly 11, further comprises:
forming a second dielectric layer 13, wherein the second dielectric layer 13 is positioned between the first substrate 10 and the first dielectric layer 12;
a first via 14 is formed, the first via 14 penetrating the second dielectric layer 13.
As shown in fig. 6, in some embodiments, after the step of forming the first via 14, further includes:
forming a trace 15, wherein the trace 15 is located on a side surface of at least part of the second dielectric layer 13 away from the first substrate 10 and in the first via hole 14; the pressure sensitive response assembly 11 further comprises a lead 112: the lead 112 is electrically connected with the piezoresistor 111; the trace 15 is electrically connected to the lead 112 through the first via 14.
As shown in fig. 8-9, in some embodiments, after bonding the second substrate 20 with the first substrate 10, further comprises:
forming a second via hole 21, wherein the second via hole 21 penetrates through the second substrate 20 and the first dielectric layer 12;
a metal layer 22 is formed, the metal layer 22 is located on a side surface of at least a portion of the second substrate 20 away from the first dielectric layer 12, and the metal layer 22 is in the second via 21, and is electrically connected to the trace 15 through the second via 21.
As shown in fig. 9, in some embodiments, after forming the second via hole 21, further includes:
forming an oxide layer 23, the oxide layer 23 being located between the second substrate 20 and the metal layer 22, and between the sidewall of the second via 21 and the metal layer 22;
a passivation layer 24 is formed, the passivation layer 24 being located on a side of the metal layer 22 remote from the second substrate 20.
As shown in fig. 9, in some embodiments, after forming the passivation layer 24, further includes:
forming a third via 241, the third via 241 penetrating the passivation layer 24;
forming a bonding layer 25, wherein the bonding layer 25 is positioned in the third via 241, and the bonding layer 25 and the metal layer 22 are electrically connected through the third via 241;
solder balls 26 are formed, the solder balls 26 being located on a side of the bonding layer 25 remote from the metal layer 22.
As shown in fig. 10, in some embodiments, after forming the solder balls 26, further comprising:
the force-bearing portion 30 is formed, the force-bearing portion 30 being located on a side of the first substrate 10 remote from the first dielectric layer 12.
In some embodiments, prior to forming the force bearing portion 30, further comprising:
the first substrate 10 is thinned.
In some embodiments, the first substrate 10 has a fourth thickness S before thinning, satisfying: s is more than or equal to 400 mu m and less than or equal to 700 mu m; the first substrate 10 has a fifth thickness T after thinning, satisfying: t is more than or equal to 100 mu m and less than or equal to 250 mu m.
Specifically, the fourth thickness S is in a range of one or both of 400 μm, 500 μm, 600 μm, and 700 μm. The fifth thickness T is one or two of 100 μm, 150 μm, 200 μm, and 250 μm.
By first thinning the first substrate 10 and then forming the force bearing portion 30, the sensitivity of the microelectromechanical pressure sensor can be improved while also reducing the thickness of the device, thereby reducing the thickness of the device package.
As shown in fig. 1-2, in some embodiments, after forming the solder balls 26, further comprises:
providing a circuit board 40;
the solder balls 26 are electrically connected to the wiring board 40.
In some embodiments, after electrically connecting the solder balls 26 with the wiring board 40, further comprising:
the plastic package 50 is formed, and the plastic package 50 is located at a side of the circuit board 40 facing the force bearing portion 30.
In some embodiments, after bonding the second substrate 20 with the first substrate 10, further comprising:
the second substrate 20 is thinned.
In some embodiments, the second substrate 20 has a sixth thickness E before thinning, satisfying: e is more than or equal to 400 mu m and less than or equal to 700 mu m; the second substrate 20 has a seventh thickness F after thinning, satisfying: f is more than or equal to 100 mu m and less than or equal to 250 mu m.
Specifically, the sixth thickness E is a range of any one or both of 400 μm, 500 μm, 600 μm, and 700 μm. The seventh thickness T is one or two of 100 μm, 150 μm, 200 μm, and 250 μm.
By thinning the second substrate 20, the thickness of the device is reduced, thereby reducing the thickness of the device package, and the sensitivity of the microelectromechanical pressure sensor can be further improved.
According to the preparation method of the piezoresistive pressure sensor, the first dielectric layer 12 is formed on the first substrate 10, the cavity 121 is formed in the first dielectric layer 12, the height consistency of the cavity 121 is good, the spacing consistency is good, the first dielectric layer 12 is used for bonding connection with the second substrate 20, and the piezoresistive pressure sensor has the advantages of being small in packaging size, simple in manufacturing procedure and the like. Further, by forming the cavity 121 in the first dielectric layer 12, the device provides a space for deformation of the pressure sensitive film under the action of a tiny stress, and by controlling the height H of the cavity 121 to be smaller than or equal to the first thickness M of the first dielectric layer 12, the limiting effect of the cavity shallow on the pressure sensitive film is good, and the reliability of the device is improved. Further, by making the openings in the second dielectric layer 13, making the openings in the second substrate 20 and the first dielectric layer 12, and making the openings in the passivation layer 24, transmission and detection of the electrical signal of the pressure sensitive sensor assembly 11 are achieved, and wafer level packaging of the device is achieved, and the packaging process is simple. Further, by thinning the first substrate 10 before forming the force-bearing portion 30, the thickness of the device is reduced, thereby reducing the thickness of the device package. In addition, by thinning the first substrate 10 and the second substrate 20, the thickness of the device is reduced, and thus the package thickness of the device is reduced. Further, the present application may reduce the device size by using solder balls 26 as the terminals of the pressure sensitive response assembly 11. The plastic package part 50 can block outside water vapor from entering the device, so that the reliability and the service life of the device are improved.
In summary, although the detailed description of the embodiments of the present application is given above, the above embodiments are not intended to limit the present application, and those skilled in the art will appreciate that: the technical scheme described in the foregoing embodiments can be modified or some of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims (14)

1. A method of manufacturing a microelectromechanical pressure sensor, comprising:
providing a first substrate (10);
-providing a pressure sensitive stress assembly (11), the pressure sensitive stress assembly (11) being located on one side of the first substrate (10), the pressure sensitive stress assembly (11) comprising a piezo-resistor (111);
forming a first dielectric layer (12), wherein the first dielectric layer (12) is positioned on one side of the pressure sensitive response component (11) away from the first substrate (10);
forming a cavity (121), wherein the cavity (121) penetrates through the first dielectric layer (12), and the orthographic projection of the cavity (121) on the first substrate (10) covers the orthographic projection of the piezoresistor (111) on the first substrate (10);
providing a second substrate (20);
melt-bonding the second substrate (20) to the first substrate (10) so that the first dielectric layer (12) and the second substrate (20) are bonded to each other on the side facing the first substrate (10);
forming a second dielectric layer (13), the second dielectric layer (13) being located between the first substrate (10) and the first dielectric layer (12);
forming a first via hole (14), wherein the first via hole (14) penetrates through the second dielectric layer (13);
forming a trace (15), wherein the trace (15) is positioned on one side surface of at least part of the second dielectric layer (13) away from the first substrate (10) and in the first via hole (14);
the pressure sensitive response assembly (11) further comprises a lead (112): the lead wire (112) is electrically connected with the piezoresistor (111); the wire (15) is electrically connected with the lead (112) through the first via hole (14);
-thinning the second substrate (20);
forming a second via (21) by a through silicon via process, wherein the second via (21) penetrates through the second substrate (20) and the first dielectric layer (12);
a metal layer (22) is formed, the metal layer (22) is located on a side surface of at least part of the second substrate (20) far away from the first dielectric layer (12), and in the second via hole (21), and the metal layer (22) is electrically connected with the routing (15) through the second via hole (21).
2. The method of manufacturing a microelectromechanical pressure sensor of claim 1, characterized in that, after forming the second via (21), it further comprises:
-forming an oxide layer (23), the oxide layer (23) being located between the second substrate (20) and the metal layer (22), and between the sidewalls of the second via (21) and the metal layer (22);
a passivation layer (24) is formed, the passivation layer (24) being located on a side of the metal layer (22) remote from the second substrate (20).
3. The method of manufacturing a microelectromechanical pressure sensor of claim 2, characterized in that, after forming the passivation layer (24), it further comprises:
forming a third via (241), the third via (241) penetrating the passivation layer (24);
forming a bonding layer (25), wherein the bonding layer (25) is positioned in the third via hole (241), and the bonding layer (25) and the metal layer (22) are electrically connected through the third via hole (241);
-forming solder balls (26), said solder balls (26) being located on a side of said bonding layer (25) remote from said metal layer (22), said solder balls (26) being electrically connected to said bonding layer (25).
4. A method of manufacturing a microelectromechanical pressure sensor of claim 3, characterized in that, after forming the solder balls (26), it further comprises:
a force-bearing portion (30) is formed, the force-bearing portion (30) being located on a side of the first substrate (10) remote from the first dielectric layer (12).
5. The method of manufacturing a microelectromechanical pressure sensor of claim 4, characterized in that before forming the force-bearing portion (30), it further comprises:
the first substrate (10) is thinned.
6. The method of manufacturing a microelectromechanical pressure sensor of claim 4, characterized in that, after forming the solder balls (26), it further comprises:
providing a circuit board (40);
the solder balls (26) are electrically connected to the wiring board (40).
7. The method of manufacturing a microelectromechanical pressure sensor of claim 6, characterized in that, after electrically connecting the solder balls (26) with the circuit board (40), it further comprises:
a plastic package part (50) is formed, and the plastic package part (50) is positioned on one side of the circuit board (40) facing the force bearing part (30).
8. A microelectromechanical pressure sensor, characterized in that it is manufactured by a method for manufacturing a microelectromechanical pressure sensor according to any of claims 1-7, comprising:
a first substrate (10);
-a pressure sensitive stress assembly (11), the pressure sensitive stress assembly (11) being located on one side of the first substrate (10); the pressure sensitive response assembly (11) comprises a piezo-resistor (111);
a first dielectric layer (12), the first dielectric layer (12) being located on a side of the pressure sensitive response component (11) remote from the first substrate (10); a cavity (121) is arranged in the first dielectric layer (12), and the cavity (121) penetrates through the first dielectric layer (12); -an orthographic projection of the cavity (121) on the first substrate (10) covers an orthographic projection of the varistor (111) on the first substrate (10);
a second substrate (20), the first dielectric layer (12) being bonded to a side of the second substrate (20) facing the first substrate (10);
a second dielectric layer (13), the second dielectric layer (13) being located between the first substrate (10) and the first dielectric layer (12);
a first via (14), wherein the first via (14) penetrates through the second dielectric layer (13);
a trace (15), wherein the trace (15) is located on a side surface of at least part of the second dielectric layer (13) away from the first substrate (10) and in the first via hole (14);
the pressure sensitive response assembly (11) further comprises a lead (112): the lead wire (112) is electrically connected with the piezoresistor (111); the wire (15) is electrically connected with the lead (112) through the first via hole (14);
a second via (21), the second via (21) penetrating the second substrate (20) and the first dielectric layer (12);
and the metal layer (22), wherein the metal layer (22) is positioned on one side surface of at least part of the second substrate (20) far away from the first dielectric layer (12) and in the second through hole (21), and the metal layer (22) is electrically connected with the wiring (15) through the second through hole (21).
9. The microelectromechanical pressure sensor of claim 8, characterized in that it further comprises:
an oxide layer (23), the oxide layer (23) being located between the second substrate (20) and the metal layer (22), and between the sidewall of the second via (21) and the metal layer (22);
-a passivation layer (24), the passivation layer (24) being located on a side of the metal layer (22) remote from the second substrate (20).
10. The microelectromechanical pressure sensor of claim 9, characterized in that it further comprises:
-a third via (241), the third via (241) penetrating the passivation layer (24);
a bonding layer (25), the bonding layer (25) being located within the third via (241), the bonding layer (25) and the metal layer (22) being electrically connected by the third via (241);
-a solder ball (26), said solder ball (26) being located on a side of said bonding layer (25) remote from said metal layer (22), said solder ball (26) being electrically connected to said bonding layer (25).
11. The microelectromechanical pressure sensor of claim 10, characterized in that it further comprises:
a force bearing portion (30), the force bearing portion (30) being arranged at a side of the first substrate (10) remote from the first dielectric layer (12);
a circuit board (40), the circuit board (40) being electrically connected to the solder balls (26);
and the plastic packaging part (50) is positioned on one side of the circuit board (40) facing the force bearing part (30).
12. The microelectromechanical pressure sensor of claim 11, characterized in that the orthographic projection of the force-carrying part (30) on the first substrate (10) at least partially overlaps with the orthographic projection of the cavity (121) on the first substrate (10).
13. The microelectromechanical pressure sensor of claim 8, characterized in that the second dielectric layer (13) comprises a first sub-dielectric layer (131) and a second sub-dielectric layer (132) arranged in a stack, the first sub-dielectric layer (131) being located on a side close to the first substrate (10).
14. The microelectromechanical pressure sensor of claim 8, characterized in that, along the thickness direction (X) of the first substrate (10), the cavity (121) has a height H, the first dielectric layer (12) has a first thickness M, satisfying: h is less than or equal to M.
CN202311536483.2A 2023-11-17 2023-11-17 Micro-electromechanical force sensor and preparation method thereof Active CN117246972B (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104634487A (en) * 2015-02-16 2015-05-20 迈尔森电子（天津）有限公司 MEMS (Micro Electro Mechanical Systems) pressure sensor and formation method thereof
CN115403005A (en) * 2022-11-02 2022-11-29 苏州敏芯微电子技术股份有限公司 Pressure sensing module, resistance type pressure sensor and manufacturing method thereof
CN116448290A (en) * 2023-06-13 2023-07-18 无锡芯感智半导体有限公司 High-frequency dynamic MEMS piezoresistive pressure sensor and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104634487A (en) * 2015-02-16 2015-05-20 迈尔森电子（天津）有限公司 MEMS (Micro Electro Mechanical Systems) pressure sensor and formation method thereof
CN115403005A (en) * 2022-11-02 2022-11-29 苏州敏芯微电子技术股份有限公司 Pressure sensing module, resistance type pressure sensor and manufacturing method thereof
CN116448290A (en) * 2023-06-13 2023-07-18 无锡芯感智半导体有限公司 High-frequency dynamic MEMS piezoresistive pressure sensor and preparation method thereof

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