WO2020248466A1

WO2020248466A1 - Back hole lead type pressure sensor and manufacturing method therefor

Info

Publication number: WO2020248466A1
Application number: PCT/CN2019/112934
Authority: WO
Inventors: 李刚; 刘迪; 胡维; 吕萍
Original assignee: 苏州敏芯微电子技术股份有限公司
Priority date: 2019-06-14
Filing date: 2019-10-24
Publication date: 2020-12-17
Also published as: CN110127597A

Abstract

A back hole lead type pressure sensor and a manufacturing method therefor. The pressure sensor is manufactured using a through hole lead technology, wire-bonding-free SMT packaging is implemented, and the packaging size of the pressure sensor is reduced. In addition, piezoresistors (201, 601) of the pressure sensor are located in a sealing cavity (220, 630), and conductive pads (202, 602) are also electrically connected to an external structure by means of through holes (212, 612); therefore, the pressure sensor is less affected by the external environment, has good device stability, and can be used for monitoring the pressure in liquid or severe environment.

Description

Back hole lead type pressure sensor and preparation method thereof

Technical field

The invention relates to the field of microelectronic mechanical systems and pressure sensors, in particular to a back hole lead type pressure sensor and a preparation method thereof.

Background technique

With the development of MEMS technology, the manufacture of pressure sensors has become a relatively mature technology. Pressure sensors can be divided into piezoresistive, capacitive, piezoelectric, etc. Among them, piezoresistive pressure sensors are used in aviation, marine, petrochemical, power machinery, etc. due to their small size, high sensitivity, and good linearity. Biomedical engineering, meteorology, geology, seismic surveying and other fields.

The common manufacturing method of piezoresistive pressure sensor is to make piezoresistance and electrodes on the upper surface of the sensitive film. For the sensor prepared by this method, one of the packaging methods is to sense the pressure on the front surface of the sensitive film. The electrode of the sensor chip and the electrode of the supporting structure (tube case) are connected together through a metal cord. This packaging requires a metal cord and a cover. The measurement medium is isolated, which leads to a large package. The other kind of package is pressure sensitive on the back side and does not need to be isolated from the measured medium. However, the piezoresistance, electrode and metal cord of the sensor are all exposed to the external environment. The metal cord is easy to break under strong vibration conditions. The device is not resistant to corrosion and has poor stability. There is also a packaging method using TSV technology, that is, filling the through holes with metal to lead, which usually leads to poor temperature characteristics of the sensor.

Summary of the invention

The technical problem to be solved by the present invention is to provide a back hole lead type pressure sensor and a preparation method thereof, which can realize non-wired patch packaging, reduce the packaging size of the pressure sensor, and have good device stability and can be used for Pressure monitoring in liquids or harsh environments.

In order to solve the above problems, the present invention provides a method for manufacturing a back-hole lead pressure sensor, which includes the following steps: providing a device substrate, the first surface of which is provided with multiple piezoresistors and multiple A conductive pad, the conductive pad is electrically connected to the piezoresistance; a supporting substrate is provided, the supporting substrate has a first surface and a second surface opposed to each other, and the first surface of the supporting substrate has a concave A groove, a plurality of through holes penetrating the supporting substrate from the first surface to the second surface; taking the first surface of the device substrate and the first surface of the supporting substrate as bonding surfaces, The device substrate is bonded to the support substrate, the groove and the first surface of the device substrate form a sealed cavity, the piezoresistance corresponds to the sealed cavity, and the through hole is Corresponding to the conductive pad, the through hole exposes the conductive pad; a plurality of electrodes are formed on the second surface of the supporting substrate, and the electrodes extend along the sidewall of the through hole and are connected to the conductive pad Electric connection.

Optionally, before the bonding step, the preparation method further includes the following step: forming an insulating layer covering the first surface of the supporting substrate, the second surface of the supporting substrate, and The inner surface of the groove and the side wall of the through hole; in the bonding step, the upper surface of the insulating layer and the first surface of the device substrate are used as bonding surfaces to connect the device substrate and The supporting substrate is bonded.

Optionally, the method for forming a plurality of the electrodes on the second surface of the supporting substrate includes the following steps: forming an electrode layer on the second surface of the supporting substrate, the electrode layer covering the supporting liner The second surface of the bottom, the sidewalls of the through hole, and the conductive pad; the electrode layer is patterned to form a plurality of the electrodes.

Optionally, the method of forming a plurality of the electrodes on the second surface of the supporting substrate includes the following steps: before the bonding step, an electrode layer is formed, and the electrode layer covers the second surface of the supporting substrate. Surface and the sidewall of the through hole; after the bonding step, pattern the electrode layer to form a plurality of initial electrodes; form a conductive transition layer on the surface of the conductive pad, and the conductive transition layer will The conductive pad is electrically connected to the initial electrode, and the initial electrode and the conductive transition layer form the electrode.

Optionally, after the step of forming the electrode, the preparation method further includes the following step: forming a solder resist layer that covers the electrode and exposes the solder that needs to be electrically connected to the external structure. point.

Optionally, the solder resist layer fills the through hole, or the solder resist layer extends along the surface of the electrode.

Optionally, after the step of forming the solder resist layer, the preparation method further includes the following step: forming a conductive bump at the solder joint of the electrode, and the conductive bump is used to connect the electrode with The external structure is electrically connected.

The present invention also provides a back-hole lead pressure sensor prepared by the above-mentioned preparation method, which comprises: a device layer in which a plurality of piezoresistors and a plurality of conductive pads are arranged, and the conductive pad is The piezoresistive electrical connection; a support layer bonded to the device layer, the support layer has a groove and a plurality of through holes penetrating the support layer, the groove and the device layer form a seal Cavity, the piezoresistance is arranged corresponding to the sealed cavity, the conductive pad is arranged corresponding to the through hole; a plurality of electrodes are arranged on the unbonded surface of the support layer, and the electrodes are along the side of the through hole The wall extends and is electrically connected to the conductive pad.

Optionally, the back hole lead type pressure sensor further includes an insulating layer disposed between the electrode and the supporting layer.

Optionally, the back-hole lead type pressure sensor further includes a conductive transition layer disposed on the surface of the conductive pad, and the electrode is electrically connected to the conductive pad through the conductive transition layer.

Optionally, the back hole lead type pressure sensor further includes a solder resist layer covering the electrode and exposing the solder joints where the electrode needs to be electrically connected to an external structure.

Optionally, the back hole lead type pressure sensor further includes a plurality of conductive bumps, and the conductive bumps are arranged on the electrodes for electrically connecting the electrodes with an external structure.

The advantage of the present invention is that the pressure sensor is prepared by using the through-hole lead technology to realize the non-wired patch package and reduce the package size of the pressure sensor; at the same time, the piezoresistance of the pressure sensor is located in the sealed cavity, and the conductive pad is also connected to the pressure sensor through the through hole. The external structure is electrically connected, less affected by the external environment, and the device has good stability, which can be used for pressure monitoring in liquids or harsh environments.

Description of the drawings

1 is a schematic diagram of the steps of the first specific embodiment of the manufacturing method of the back hole lead type pressure sensor of the present invention;

2A to 2H are process flow diagrams of the first specific embodiment of the manufacturing method of the back hole lead type pressure sensor of the present invention;

3A to 3D are process flow diagrams of forming a device substrate in the first specific embodiment;

4 is a process flow chart of forming a solder resist layer in the second specific embodiment of the method for manufacturing a back hole lead pressure sensor of the present invention;

5A to 5D are process flow diagrams of forming electrodes in the third embodiment of the manufacturing method of the back hole lead type pressure sensor of the present invention;

Fig. 6 is a schematic structural diagram of a first specific embodiment of a back hole lead type pressure sensor;

FIG. 7 is a schematic structural diagram of a second specific embodiment of a back hole lead type pressure sensor;

FIG. 8 is a schematic structural diagram of a third embodiment of a back hole lead type pressure sensor.

Detailed ways

The specific implementation of the back hole lead type pressure sensor and the preparation method thereof provided by the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the steps of the first specific embodiment of the manufacturing method of the back hole lead type pressure sensor of the present invention. Referring to FIG. 1, the preparation method includes the following steps: step S10, a device substrate is provided, a first surface of the device substrate is provided with a plurality of piezoresistors and a plurality of conductive pads, the conductive pad and the Piezoresistive electrical connection; step S11, a supporting substrate is provided, the supporting substrate has a first surface and a second surface oppositely arranged, the first surface of the supporting substrate has a groove, and a plurality of through holes The first surface to the second surface penetrate the supporting substrate; step S12, using the first surface of the device substrate and the first surface of the supporting substrate as bonding surfaces, the device The substrate is bonded to the supporting substrate, the groove and the first surface of the device substrate form a sealed cavity, the piezoresistance corresponds to the sealed cavity, and the through hole is connected to the conductive pad Correspondingly, the conductive pad is exposed by the through hole; step S13, a plurality of electrodes are formed on the second surface of the supporting substrate, and the electrodes extend along the sidewall of the through hole and are electrically connected to the conductive pad. connection.

2A to 2H are process flow diagrams of the first specific embodiment of the manufacturing method of the back hole lead type pressure sensor of the present invention.

Referring to step S10 and FIG. 2A, a device substrate 200 is provided. A first surface 200A of the device substrate 200 is provided with a plurality of piezoresistors 201 and a plurality of conductive pads 202. The conductive pads 202 and the piezoresistors 201 electrical connection.

In this embodiment, the method of forming the device substrate 200 includes the following steps:

Referring to FIG. 3A, a first substrate 300 is provided. The first substrate 300 has a first surface 300A, and a first insulating layer 301 covers the first surface 300A of the first substrate 300. The first substrate 300 includes but is not limited to single crystal silicon or SOI wafer. If the first substrate 300 is an SOI silicon wafer, the upper silicon thickness of the SOI wafer needs to meet the thickness requirement of the sensitive film. The first insulating layer 301 can be formed by a thermal oxidation process, which can reduce the channel effect of ion implantation in the subsequent process of forming piezoresistance.

Referring to FIG. 3B, a plurality of piezoresistors 201 and a plurality of concentrated boron wires 302 electrically connected to the piezoresistors 201 are formed on the first surface 300A of the first substrate 300, wherein the piezoresistors 201 are Light boron piezoresistance. In this step, the light boron piezoresistor 302 and the concentrated boron wire 302 can be fabricated by photolithography and ion implantation. The piezoresistor 201 is a strained piezoresistance formed by light boron diffusion, and the concentrated boron wire 302 is a concentrated boron ohmic contact area formed by injecting concentrated boron. In this specific embodiment, four piezoresistors 201 (two piezoresistors 201 are shown in the figure) are connected by a concentrated boron wire 302 to form a Wheatstone bridge. In other specific embodiments of the present invention, eight piezoresistors 201 may also be used.

3C, the first insulating layer 301 is patterned to form a plurality of openings 301A on the first insulating layer 301, and the openings 301A expose the surface of the concentrated boron wire 302. In this step, the opening 301A can be formed by photolithography and etching processes.

Referring to FIG. 3D, a plurality of conductive pads 202 are formed at the opening 301A, and the conductive pads 202 are electrically connected to the concentrated boron wire 302, thereby forming the device substrate 200. In this step, the conductive pad 202 is a metal, which can be made by sputtering or deposition, photolithography and etching, wet etching or dry etching. In other specific embodiments of the present invention, the conductive pad 202 may also be polysilicon, which may be formed by a doping process.

Optionally, in other specific embodiments of the present invention, after forming the conductive pad 202, a passivation layer (not shown in the drawings) may be further formed, and the conductive pad is exposed to the passivation layer. In this step, a passivation layer can be deposited first, and then the conductive pad is exposed by photolithography and etching processes. The passivation layer can be used to protect the conductive pad 202 and the passivation layer can be used as a bonding layer for subsequent bonding. In this specific embodiment, the passivation layer is not formed.

Referring to step S11 and FIG. 2B, a supporting substrate 210 is provided, and the supporting substrate 210 has a first surface 210A and a second surface 210B opposite to each other. The supporting substrate 210 includes, but is not limited to, a silicon substrate, a glass substrate, and the like. In this embodiment, the support substrate 210 is a silicon wafer with a thickness of 400 microns. In other embodiments of the present invention, the thickness of the support substrate 210 may not be limited to 400 microns.

The first surface 210A of the supporting substrate 210 has a groove 211. In this step, the groove 211 can be formed on the first surface 210A of the supporting substrate 210 by using photolithography and etching processes. It can be understood that the groove 211 does not penetrate the supporting substrate 210. The shape of the groove 211 includes, but is not limited to, a rectangle, a circle, or a polygon.

A plurality of through holes 212 penetrate the supporting substrate 210 from the first surface 210A to the second surface 210B. In this embodiment, the second surface 210B of the support substrate 210 may be subjected to photolithography and etching processes to form the through hole 212. Further, the through hole 212 is located outside the groove 211, that is, a plurality of the through holes 212 are arranged around the groove 211. The number of the through holes 212 may correspond to the number of the conductive pads 202. The shape of the through hole 212 includes, but is not limited to, a rectangle, a circle, or a polygon.

Optionally, this specific embodiment further includes a step of forming a second insulating layer 213. 2C, a second insulating layer 213 is formed. The second insulating layer 213 covers the first surface 210A of the supporting substrate 210, the second surface 210B of the supporting substrate 210, and the groove 211 The inner surface and the side wall of the through hole 212. In this step, the second insulating layer 213 may be formed by thermal oxidation or LPCVD process. The function of the second insulating layer 213 is to insulate the supporting substrate 210 from subsequently formed electrodes. It is understandable that if the supporting substrate 210 is a non-insulating substrate, the second insulating layer needs to be formed; if the supporting substrate 210 is an insulating substrate, the second insulating layer may not be formed. Specifically, in this embodiment, the supporting substrate 210 is a silicon substrate, and the second insulating layer 213 needs to be formed to insulate the electrode from the supporting substrate 210; in another aspect of the present invention In specific embodiments, the supporting substrate is a glass substrate, and since the glass substrate itself has insulating properties, the second insulating layer may not be formed.

Referring to step S12 and FIG. 2D, using the first surface 200A of the device substrate 200 and the first surface 210A of the supporting substrate 210 as bonding surfaces, the device substrate 200 and the supporting substrate 210 bonding. In this embodiment, the upper surface of the first insulating layer 301 and the upper surface of the second insulating layer 213 are used as bonding surfaces, and the device substrate 200 is bonded to the supporting substrate 210 .

In this step, the bonding process of the device substrate 200 and the supporting substrate 210 includes, but is not limited to, low-temperature Si-Si fusion bonding, high-temperature Si-Si fusion bonding, and Si-Glass anodic bonding. Specifically, in this embodiment, the conductive pad 202 is metallic aluminum, and the bonding process of the device substrate 200 and the supporting substrate 210 is low-temperature Si-Si fusion bonding, and the bonding The temperature does not exceed the melting point of the conductive pad 202 at 660°C; in another specific embodiment of the present invention, the conductive pad 202 is polysilicon, and the bonding process of the device substrate 200 and the supporting substrate 210 is For high-temperature Si-Si fusion bonding, the bonding temperature does not exceed the melting point of the conductive pad 202 at 1410°C; in another specific embodiment of the present invention, the conductive pad 202 is polysilicon, and the supporting substrate 210 is glass Substrate, the bonding process of the device substrate 200 and the supporting substrate 210 is Si-Glass anode bonding.

After the device substrate 200 and the supporting substrate 210 are bonded, the groove 211 and the first surface 200A of the device substrate 200 form a sealed cavity 220. In this embodiment, the groove 211 and the upper surface of the first insulating layer 301 form the sealed cavity 220. The piezoresistor 201 corresponds to the sealed cavity 220, that is, the piezoresistor 201 is located within the projection range of the sealed cavity 220. The through hole 212 corresponds to the conductive pad 202, and the through hole 212 exposes the conductive pad 202, that is, from the direction of the second surface 210B of the supporting substrate 210, the conductive pad 202 can be observed .

Optionally, before the bonding step, a step of aligning the device substrate 200 and the supporting substrate 210 is further included. The effect of this step is to ensure that the piezoresistance 201 corresponds to the sealed cavity 220 and the through hole 212 corresponds to the conductive pad 202. Optionally, before the bonding step, a step of polishing the surface of the device substrate 200 is further included. In this specific embodiment, since the bonding surface of the device substrate 200 is the surface of the first insulating layer 301, before the bonding step, the first insulating layer 301 on the surface of the device substrate 200 is polished. To make its flatness meet the bonding requirements.

Optionally, referring to FIG. 2E, in this specific embodiment, after the bonding step is completed, the device substrate 200 is applied to the device substrate 200 from a surface of the device substrate 200 opposite to the first surface 200A. Perform thinning and polishing. After the thinning and polishing process is completed, the thickness of the device substrate 200 can be reduced to several microns. If the device substrate 200 is a SOI substrate, it is first thinned, thinning to close when the intermediate SiO ₂ layer SOI substrate, a wet etched SiO _2, to give the top layer Si film.

Referring to step S13 and FIG. 2F, a plurality of electrodes 230 are formed on the second surface 210B of the supporting substrate 210, and the electrodes 230 extend along the sidewall of the through hole 212 and are electrically connected to the conductive pad 202. In this embodiment, the specific steps of forming the electrode 230 are: first, an electrode layer (not shown in the drawings) is formed on the second surface 210B of the supporting substrate 210, and the electrode layer covers the The second surface 210B of the supporting substrate 210, the sidewalls of the through holes 212, and the conductive pad 202; secondly, the electrode layer is patterned to form a plurality of the electrodes 230, wherein photolithography and etching can be used The electrode layer is patterned by processes such as etching to form the electrode 230.

In this step, the electrode 230 extends along the sidewall of the through hole 212 instead of filling the through hole 212. If the electrode 230 fills the through hole 212, the temperature characteristic of the sensor will deteriorate. In this embodiment, the second insulating layer 213 is provided between the electrode 230 and the supporting substrate 210.

Optionally, referring to FIG. 2G, after the step of forming the electrode 230, the preparation method further includes the following steps: forming a solder resist layer 240, the solder resist layer 240 covering the electrode 230 and exposing the The electrode 230 needs a solder joint 230A that is electrically connected to the external structure. In this embodiment, the solder resist layer is an organic oligomer, which fills the through hole 212 to improve the performance of the sensor. In the second embodiment of the present invention, referring to FIG. 4, the solder resist layer 240 is made of inorganic materials such as silicon nitride, silicon oxide, silicon oxynitride, etc., which extends along the surface of the electrode 230, that is, the resist The solder layer 240 covers the electrode 230 in the form of a film.

Optionally, referring to FIG. 2H, a conductive bump 250 is formed at the solder joint 230A of the electrode 230, and the conductive bump 250 is used to electrically connect the electrode 230 with an external structure. In this specific embodiment, ball reflow is performed on the solder joint 230A to form the conductive bump 250. The conductive bump 250 may be electrically connected to an external printed circuit board and other structures.

In the first embodiment, the electrode 230 is formed after the bonding step, and in the third embodiment, the step of forming the electrode includes a step performed before the bonding step and a step performed after the bonding step . The specific instructions are as follows:

Referring to FIG. 5A, after the structural diagram shown in FIG. 2C, an electrode layer 500 is formed, and the electrode layer 500 covers the second surface 210B of the supporting substrate 210 and the sidewall of the through hole 212. The material of the electrode layer 500 is polysilicon, which can be formed by an LPCVD process.

Further, in the actual process, the electrode layer 500 also covers the first surface 210A of the supporting substrate 210 and the inner sidewall of the groove 211, so in this step, the supporting can be removed by an etching process. The electrode layer 500 on the first surface 210A of the substrate 210 and the inner sidewall of the groove 211 remains, while the electrode layer 500 covering the second surface 210B of the supporting substrate 210 and the sidewall of the through hole 212 remains. Referring to FIG. 5B, the upper surface of the first insulating layer 301 and the upper surface of the second insulating layer 213 are used as bonding surfaces to bond the device substrate 200 and the supporting substrate 210. In this step, the bonding process is high-temperature Si-Si fusion bonding, and the temperature does not exceed the melting point of polysilicon, 1410°C.

Referring to FIG. 5C, the electrode layer 500 is patterned to form a plurality of initial electrodes 501. In this step, a photolithography and etching process may be used to remove part of the electrode layer 500 on the first surface 210A of the supporting substrate 210 to form the initial electrode 501. The initial electrode 501 covers the sidewall of the through hole 212 and a part of the second surface 210B of the supporting substrate 210.

Referring to FIG. 5D, a conductive transition layer 502 is formed on the surface of the conductive pad 202, that is, the conductive transition layer 502 is formed at the bottom of the through hole 212. The material of the conductive transition layer 502 includes but is not limited to metal materials. The conductive transition layer 502 electrically connects the conductive pad 202 and the initial electrode 501, that is, the initial electrode 501 and the conductive transition layer 502 together form an electrode 510. After the electrode 510 is formed, the subsequent steps are the same as those of the first specific embodiment, and will not be described again.

In the third embodiment, the materials of the conductive pad 202 and the initial electrode 502 are both polysilicon. If the two are only directly electrically connected, the electrical connection performance is not good and the contact is poor. However, in this embodiment Wherein, the conductive transition layer 502 forms an ohmic contact with the conductive pad 202 and the initial electrode 502, which can enhance the electrical connection performance between the conductive pad 202 and the initial electrode 502.

The invention also provides specific implementations of the back-hole lead type pressure sensor prepared by the above-mentioned preparation method.

Fig. 6 is a schematic structural diagram of a first specific embodiment of a back hole lead type pressure sensor. Please refer to FIG. 6, the back hole lead type pressure sensor includes a device layer 600, a support layer 610 and a plurality of electrodes 620.

A plurality of piezoresistors 601 and a plurality of conductive pads 602 are provided in the device layer 600, and the conductive pads 602 are electrically connected to the piezoresistors 601. In this specific embodiment, the piezoresistor 601 is a light boron piezoresistor, and the light boron piezoresistor is electrically connected to the conductive pad 602 through a concentrated boron wire 603. The device layer 600 includes a first substrate 604 and a first insulating layer 605 disposed on the first substrate 604, and the piezoresistor 601 is disposed in the first substrate 604. The first insulating layer 605 has a plurality of openings (not shown in the drawings), and the conductive pad 602 is disposed in the opening, that is, the conductive pad 602 is exposed outside the first insulating layer 605.

The support layer 610 is bonded to the device layer 600. The supporting layer 610 has a groove 611 and a plurality of through holes 612 passing through the supporting layer 610. The groove 611 and the device layer 600 form a sealed cavity 630, and the piezoresistor 601 is disposed corresponding to the sealed cavity 630. The conductive pad 602 is disposed corresponding to the through hole 612, that is, the through hole 612 exposes the conductive pad 602.

The electrode 620 is disposed on the unbonded surface of the supporting layer 610, and the electrode 620 extends along the sidewall of the through hole 612 and is electrically connected to the conductive pad 602. The electrode 620 extends along the sidewall of the through hole 612 instead of filling the through hole 612. If the electrode 620 fills the through hole 612, the temperature characteristic of the back hole lead pressure sensor will be deteriorated.

In this specific embodiment, the back hole lead type pressure sensor further includes a second insulating layer 640, and the second insulating layer 640 is disposed between the electrode 620 and the supporting layer 610. Further, the second insulating layer 640 is not only disposed between the electrode 620 and the support layer 610, it also covers the entire surface of the support layer 610, the inner side wall of the groove 611, and the through hole 612. The sidewall.

Further, the back hole lead type pressure sensor further includes a solder resist layer 650 that covers the electrode 620 and exposes the solder joints 620A where the electrode 620 needs to be electrically connected to an external structure. In this embodiment, the solder resist layer 650 fills the through hole 612 to improve the performance of the sensor. In the second embodiment of the present invention, referring to FIG. 7, the solder resist layer 650 is made of inorganic materials such as silicon nitride, silicon oxide, silicon oxynitride, etc., which extends along the surface of the electrode 620, that is, the resist The solder layer 650 covers the electrode 620 in the form of a thin film.

Further, in this specific embodiment, the back-hole lead type pressure sensor further includes a plurality of conductive bumps 660, and the conductive bumps 660 are arranged on the solder joints 620A of the electrode 620 for connecting the electrode 620 is electrically connected to the external structure.

Fig. 8 is a schematic structural view of a third specific embodiment of the back hole lead type pressure sensor of the present invention. Referring to FIG. 8, the third embodiment is different from the first embodiment in that the back-hole lead type pressure sensor further includes a conductive transition layer 800. The conductive transition layer 800 is disposed on the surface of the conductive pad 602, and the electrode 620 is electrically connected to the conductive pad 602 through the conductive transition layer 800. In this embodiment, the conductive pad 602 and the electrode 620 are polysilicon, and the conductive transition layer 800 is metal. The electrode 620 does not extend to the conductive pad 602, but is connected to the conductive pad 602 through the conductive transition layer 800, which further improves the connection performance between the conductive pad 602 and the electrode 620.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be considered This is the protection scope of the present invention.

Claims

A method for preparing a back hole lead type pressure sensor is characterized in that it comprises the following steps:

Providing a device substrate, a first surface of the device substrate is provided with a plurality of piezoresistors and a plurality of conductive pads, and the conductive pads are electrically connected to the piezoresistors;

A supporting substrate is provided. The supporting substrate has a first surface and a second surface opposite to each other. The first surface of the supporting substrate has a groove, and a plurality of through holes extend from the first surface to the The second surface penetrates the supporting substrate;

Using the first surface of the device substrate and the first surface of the supporting substrate as bonding surfaces, the device substrate is bonded to the supporting substrate, and the groove is connected to the device substrate A sealed cavity is formed on the first surface of the piezoresistance, the piezoresistance corresponds to the sealed cavity, the through hole corresponds to the conductive pad, and the through hole exposes the conductive pad;

A plurality of electrodes are formed on the second surface of the supporting substrate, and the electrodes extend along the sidewalls of the through holes and are electrically connected to the conductive pads.
The preparation method according to claim 1, characterized in that, before the bonding step, the preparation method further comprises the following steps:

Forming an insulating layer, the insulating layer covering the first surface of the supporting substrate, the second surface of the supporting substrate, the inner surface of the groove and the sidewall of the through hole;

In the bonding step, the upper surface of the insulating layer and the first surface of the device substrate are used as bonding surfaces to bond the device substrate and the supporting substrate.
The manufacturing method according to claim 1, wherein the method of forming a plurality of the electrodes on the second surface of the supporting substrate comprises the following steps:

Forming an electrode layer on the second surface of the supporting substrate, the electrode layer covering the second surface of the supporting substrate, the sidewall of the through hole and the conductive pad;

The electrode layer is patterned to form a plurality of the electrodes.
The manufacturing method according to claim 1, wherein the method of forming a plurality of the electrodes on the second surface of the supporting substrate comprises the following steps:

Before the bonding step, an electrode layer is formed, the electrode layer covering the second surface of the supporting substrate and the sidewall of the through hole;

After the bonding step, pattern the electrode layer to form a plurality of initial electrodes;

A conductive transition layer is formed on the surface of the conductive pad, and the conductive transition layer electrically connects the conductive pad and the initial electrode, and the initial electrode and the conductive transition layer form the electrode.
The preparation method according to any one of claims 1 to 4, characterized in that, after the step of forming the electrode, the preparation method further comprises the following steps:

A solder resist layer is formed, the solder resist layer covers the electrode and exposes the solder joints where the electrode needs to be electrically connected to the external structure.
The manufacturing method according to claim 5, wherein the solder resist layer fills the through hole, or the solder resist layer extends along the surface of the electrode.
5. The preparation method according to claim 5, wherein after the step of forming the solder resist layer, the preparation method further comprises the following steps:

A conductive bump is formed at the solder joint of the electrode, and the conductive bump is used to electrically connect the electrode with an external structure.
The preparation method according to claim 1, wherein the method for bonding the device substrate and the supporting substrate is low-temperature Si-Si fusion bonding, high-temperature Si-Si fusion bonding, or Si-glass Anode bonding.
A back hole lead type pressure sensor prepared by using the preparation method of any one of claims 1 to 8, characterized in that it comprises:

A device layer, a plurality of piezoresistors and a plurality of conductive pads are arranged in the device layer, and the conductive pads are electrically connected to the piezoresistors;

A support layer is bonded to the device layer, the support layer has a groove and a plurality of through holes penetrating the support layer, the groove and the device layer form a sealed cavity, and the piezoresistance Corresponding to the sealed cavity, and the conductive pad is corresponding to the through hole;

A plurality of electrodes are arranged on the unbonded surface of the support layer, and the electrodes extend along the sidewalls of the through holes and are electrically connected to the conductive pads.
9. The back hole lead type pressure sensor according to claim 9, wherein the back hole lead type pressure sensor further comprises an insulating layer disposed between the electrode and the support layer.
The back hole lead type pressure sensor according to claim 9, characterized in that the back hole lead type pressure sensor further comprises a conductive transition layer, the conductive transition layer is arranged on the surface of the conductive pad, and the electrode passes through The conductive transition layer is electrically connected to the conductive pad.
The back hole lead type pressure sensor according to any one of claims 9 to 11, wherein the back hole lead type pressure sensor further comprises a solder resist layer, the solder resist layer covering the electrode and exposing The electrodes require solder joints that are electrically connected to the external structure.
The back hole lead type pressure sensor according to claim 12, wherein the solder resist layer fills the through hole, or the solder resist layer extends along the surface of the electrode.
The back hole lead type pressure sensor according to any one of claims 9 to 11, wherein the back hole lead type pressure sensor further comprises a plurality of conductive bumps, and the conductive bumps are arranged on the electrode , Used to electrically connect the electrode with the external structure.