CN217901063U - Pressure sensor - Google Patents

Abstract

The utility model relates to a pressure sensor technical field discloses a pressure sensor, including folding in proper order and establishing: the first glass layer is provided with pressure holes; the silicon substrate is provided with a pressure cavity, a pressure sensing diaphragm capable of bearing external pressure is formed in the area, opposite to the pressure cavity, of the silicon substrate, and the silicon substrate is provided with a piezoresistor and an electric connection layer; the insulating layer is formed on the silicon substrate, and a metal connecting piece is arranged on the insulating layer; the silicon bonding layer is formed on the insulating layer and is arranged at intervals with the metal connecting piece; and the second glass layer is fixed on the silicon bonding layer, and the second glass layer, the silicon bonding layer and the insulating layer form a vacuum cavity which is just opposite to the pressure cavity. The utility model discloses a pressure sensor, simple structure adds the liquid encapsulation technology that need not to carry on man-hour, and the yield is high, but direct measurement external pressure, and response time is short.

Description

Pressure sensor

Technical Field

The utility model relates to a pressure sensor technical field especially relates to a pressure sensor.

Background

The existing pressure sensor comprises a liquid cavity and a pressure transmitter, wherein liquid such as oil or water is packaged in the liquid cavity, and the pressure transmitter is used for detecting the pressure of the liquid in the liquid cavity. When the pressure sensor is under the external pressure, the liquid is under the same acting force, and the liquid pressure detected by the pressure transmitter is the external pressure. The pressure sensor is internally packaged with liquid, so that the packaging process is complex, the liquid is possibly leaked if the sealing is incomplete, the pressure sensor fails, the dynamic characteristic of the pressure sensor is reduced, and the response time is prolonged.

SUMMERY OF THE UTILITY MODEL

Based on the above, an object of the utility model is to provide a pressure sensor, but direct measurement external pressure, response time is short, simple structure, does not contain liquid in it, need not to carry out liquid encapsulation technology man-hour, and the yield is high.

In order to achieve the purpose, the utility model adopts the following technical proposal:

a pressure sensor comprising, stacked in sequence: the first glass layer is provided with pressure holes; the silicon substrate is provided with a pressure cavity opposite to the pressure hole, a pressure sensing diaphragm capable of bearing external pressure is formed in the area of the silicon substrate opposite to the pressure cavity, and the silicon substrate is provided with a piezoresistor and an electric connection layer; the insulating layer is formed on the silicon substrate, and a metal connecting piece is arranged on the insulating layer; the silicon bonding layer is formed on the insulating layer and is arranged at intervals with the metal connecting piece; and the second glass layer is fixed on the silicon bonding layer, and the second glass layer, the silicon bonding layer and the insulating layer form a vacuum cavity facing the pressure cavity.

As a preferred scheme of pressure sensor, pressure sensor still include with the base plate of silicon bonding layer laminating, the base plate with metal connecting piece fixed connection just is equipped with the mounting groove on it, the inner wall of mounting groove with the surface laminating on second glass layer.

As a preferable aspect of the pressure sensor, the second glass layer is bonded in the mounting groove.

As a preferable scheme of the pressure sensor, the substrate is further provided with a conducting wire, a first metal PAD and a welding part, wherein the conducting wire, the first metal PAD and the welding part are electrically connected, the first metal PAD is formed on the surface of the substrate and is electrically connected with the conducting wire, the welding part is formed on the first metal PAD, the welding part can be welded with the metal connecting part, and the conducting wire can transmit an electric signal outwards.

As a preferable aspect of the pressure sensor, the metal connecting member includes a second metal PAD and a metal connecting layer, the second metal PAD penetrates through the insulating layer, and the metal connecting layer is formed on a surface of the insulating layer and electrically connected to the solder member.

As a pressure sensor's preferred scheme, be equipped with on the silicon bonding layer and dodge hole and isolation tank, it is just right to dodge the hole the vacuum cavity sets up, the isolation tank separates the silicon bonding layer for mutual contactless isolation silicon layer and inner circle silicon layer, the inner circle silicon layer is located isolation silicon layer's inboard, isolation silicon layer is located metal connecting piece first metal PAD reaches the inboard of welding.

As a preferred embodiment of the pressure sensor, the piezoresistor is arranged opposite to the edge of the pressure chamber.

As a preferable aspect of the pressure sensor, the electrical connection layer is a lead layer, the number of the piezoresistors is four, and the four piezoresistors are connected through the electrical connection layer to form a wheatstone bridge.

As a preferable aspect of the pressure sensor, the insulating layer includes at least one of a silicon oxide layer, an aluminum oxide layer, and a silicon nitride layer.

As a preferable scheme of the pressure sensor, the silicon bonding layer is a polysilicon layer or an amorphous silicon layer.

The utility model has the advantages that: the utility model discloses a pressure sensor, moreover, the steam generator is simple in structure, be located the outside metal connecting piece of silicon bonding layer, make pressure sensor suitably install other structurally, act on when the external pressure is in the pressure chamber, thereby piezo-resistor passes through pressure chamber receiving pressure and produces deformation, thereby make piezo-resistor's resistivity change, form the signal of telecommunication, this signal of telecommunication passes through metal connecting piece and exports to external circuit, realize the detection to external pressure, response time is short, because do not contain liquid in this pressure sensor, need not to carry out liquid encapsulation technology, pressure sensor's the production degree of difficulty has been reduced, pressure sensor's yield has been promoted.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the contents of the embodiments of the present invention and the drawings without creative efforts.

Fig. 1 is a cross-sectional view of a pressure sensor according to an embodiment of the present invention;

fig. 2 is a partial enlarged view of fig. 1 at a.

In the figure:

1. a first glass layer; 10. a pressure port;

2. a silicon substrate; 20. a pressure chamber; 21. a pressure-sensitive film; 22. a voltage dependent resistor; 23. an electrical connection layer;

3. an insulating layer; 31. a metal connecting member; 311. a second metal PAD; 312. a metal connection layer;

4. a silicon bonding layer; 40. avoiding holes; 402. an isolation trench; 41. an isolation silicon layer; 42. an inner ring silicon layer;

5. a second glass layer; 50. a vacuum chamber;

6. a substrate; 61. a wire; 62. a first metal PAD; 63. and (7) welding parts.

Detailed Description

In order to make the technical problems, technical solutions and technical effects achieved by the present invention more clear, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings, and obviously, the described embodiments are only some embodiments, not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection or a removable connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood as a specific case by those skilled in the art.

The embodiment provides a pressure sensor, as shown in fig. 1 and fig. 2, the pressure sensor includes a first glass layer 1, a silicon substrate 2, an insulating layer 3, a silicon bonding layer 4, and a second glass layer 5, which are sequentially stacked, a pressure hole 10 is formed on the first glass layer 1, a pressure chamber 20 facing the pressure hole 10 is formed on the silicon substrate 2, a pressure sensing diaphragm 21 capable of bearing external pressure is formed in a region where the silicon substrate 2 faces the pressure chamber 20, and a piezoresistor 22 and an electrical connection layer 23 are formed on the silicon substrate 2. As shown in fig. 1, an insulating layer 3 is formed on a silicon substrate 2, a metal connector 31 is provided on the insulating layer 3, a silicon bonding layer 4 is formed on the insulating layer 3, and the silicon bonding layer 4 is provided at an interval from the metal connector 31. As shown in fig. 1, the second glass layer 5 is fixed on the silicon bonding layer 4, and the second glass layer 5, the silicon bonding layer 4 and the insulating layer 3 form a vacuum chamber 50 facing the pressure chamber 20. The vacuum chamber 50 of this embodiment provides a deformation space for the pressure sensing diaphragm 21 of the pressure sensor, so as to improve the sensing sensitivity, and the depth of the vacuum chamber 50 can be set by those skilled in the art according to the actual use condition, which is not specifically limited in this embodiment.

The pressure sensor that this embodiment provided, moreover, the steam generator is simple in structure, be located the outside metal connecting piece 31 of silicon bonding layer 4, make pressure sensor suitably install on other structures, when external pressure is used in pressure chamber 20, thereby piezo-resistor 22 produces deformation through pressure chamber 20 received pressure, make piezo-resistor 22's resistivity change, form the signal of telecommunication, this signal of telecommunication passes through metal connecting piece 31 output to external circuit, realize the detection to ambient pressure, response time is short, because do not contain liquid in this pressure sensor, need not to carry out liquid packaging technology, pressure sensor's the production degree of difficulty has been reduced, pressure sensor's yield has been promoted.

The electrical connection layer 23 of this embodiment is a lead layer made of concentrated boron, which is located on one side of the varistor 22. The number of the piezoresistors 22 in the embodiment is four, the four piezoresistors 22 are connected into a wheatstone bridge through the electric connecting layer 23, and the piezoresistors 22 are arranged right opposite to the edge of the pressure cavity 20, so that the piezoresistors 22 are positioned at the maximum stress position of the pressure sensing film 21, and the sensitivity of the pressure sensor is improved as much as possible. In other embodiments, the electrical connection layer 23 may also be an ohmic contact layer, and the ohmic contact layer is formed on the piezoresistor 22 by concentrated boron, and is specifically configured according to actual needs.

Specifically, the metal connection component 31 of the present embodiment includes a second metal PAD 311 and a metal connection layer 312, which are electrically connected, the second metal PAD 311 penetrates through the insulating layer 3, and the metal connection layer 312 is formed on the surface of the insulating layer 3 and is electrically connected to the solder 63. The material of the metal connecting member 31 of this embodiment is metal, preferably at least one of Al, ti, au, cu, and Pt, the shape of the cross section of the metal connecting member 31 may be circular, square, or other shapes, and this embodiment is not particularly limited, and is specifically determined according to the actual use situation.

In the present embodiment, the insulating layer 3 is a single silicon oxide layer, and the insulating layer 3 is formed on the oxide layer of the SOI substrate, the electrical connection layer 23, and the varistor 22. In other embodiments, the insulating layer 3 may also be a single-layer structure formed by an insulating material such as silicon nitride or aluminum oxide, or at least a two-layer structure formed by an insulating material such as silicon oxide, silicon nitride, or aluminum oxide, which is specifically selected according to actual needs. The pressure cavity 20 of the embodiment is a circular groove, the side wall of the pressure cavity 20 extends along the thickness direction of the SOI substrate, the pressure cavity 20 is formed by dry etching, the pressure hole 10 on the first glass layer 1 is a circular hole, and the diameter of the pressure hole 10 is smaller than that of the pressure cavity 20 of the SOI substrate, so that the first glass layer 1 can better protect the SOI substrate, the possibility of damaging the SOI substrate is reduced, the service life of the SOI substrate is prolonged, and the service life of the pressure sensor is prolonged. In other embodiments, the diameter of the pressure hole 10 on the first glass layer 1 may also be equal to the diameter of the pressure chamber 20, and the pressure hole 10 and the pressure chamber 20 are distributed coaxially. In other embodiments, the pressure chamber 20 may also be formed by wet etching, where a sidewall of the pressure chamber 20 forms an angle with the thickness direction of the SOI substrate, and the diameter of the pressure chamber 20 gradually decreases along the direction of increasing the depth of the pressure chamber 20, where the diameter of the pressure hole 10 in the first glass layer 1 is smaller than or equal to the maximum diameter of the pressure chamber 20 of the SOI substrate.

The silicon bonding layer 4 of this embodiment is formed by a deposition process, and is a polysilicon layer or an amorphous silicon layer, the polysilicon layer is made of polysilicon, and the amorphous silicon layer is made of α -Si. The silicon bonding layer 4 is provided with a relief hole 40, and the relief hole 40 is arranged right opposite to the vacuum cavity 50. Because the structural strength of silicon bonding layer 4 is great, the hole 40 of dodging on silicon bonding layer 4 can avoid silicon bonding layer 4 to the influence of pressure sensing diaphragm 21, guarantees pressure sensing diaphragm 21's deflection to improve pressure sensor's measurement accuracy.

As shown in fig. 1, the pressure sensor of the present embodiment further includes a substrate 6, the substrate 6 is fixedly connected to the metal connecting member 31 and is provided with an installation groove, and an inner wall of the installation groove is attached to the surface of the second glass layer 5. In order to increase the structural strength of the pressure sensor, the area of the second glass layer 5 in contact with the mounting groove may be coated with an adhesive, and the second glass layer 5 is adhered in the mounting groove. The substrate 6 is a PCB, a ceramic board or other substrate 6, and this embodiment is not limited in particular.

As shown in fig. 1 and 2, a conductive line 61, a first metal PAD 62, and a solder part 63 are electrically connected to the substrate 6, the first metal PAD 62 is formed on the surface of the substrate 6 and connected to the conductive line 61, the solder part 63 is formed on the first metal PAD 62, the solder part 63 can be soldered to the metal connecting member 31, and the conductive line 61 can transmit an electrical signal to the outside. The material of the lead 61 and the first metal PAD 62 of this embodiment is copper, the solder part 63 is a tin layer, and the solder part 63 and the metal connecting layer 312 are soldered together. It should be noted that the shape of the lead 61 on the substrate 6 is not limited to the linear shape shown in fig. 1, and may be other shapes, specifically, according to actual needs.

Specifically, the material of the first metal PAD 62 in this embodiment is a metal, preferably at least one of Al, ti, au, cu, and Pt, and the shape of the cross section of the first metal PAD 62 may be a circle, a square, or other shapes, and this embodiment is not particularly limited, and is determined according to the actual use situation.

As shown in fig. 2, an isolation groove 402 is formed in the silicon bonding layer 4 of this embodiment, the isolation groove 402 is disposed in a region of the silicon bonding layer 4 close to the metal connector 31, the isolation groove 402 separates the silicon bonding layer 4 into an isolation silicon layer 41 and an inner ring silicon layer 42 which are not in contact with each other, the inner ring silicon layer 42 is located inside the isolation silicon layer 41, and the isolation silicon layer 41 is located inside the metal connector 31, the first metal PAD 62, and the solder part 63. Even if the metal connecting piece 31, the first metal PAD 62 or the welding piece 63 is in contact with the isolation silicon layer 41 on the outer ring of the silicon bonding layer 4, the isolation silicon layer 41 is not in contact with the inner ring silicon layer 42, the inner ring silicon layer 42 on the inner ring of the silicon bonding layer 4 is not electrified, and the safety of the pressure sensor is improved.

Further, the pressure sensor of the present embodiment is manufactured by the following processing method:

s1, providing a silicon substrate 2;

s2, forming a first photoresist layer on the lower surface of the silicon substrate 2;

s3, patterning the first photoresist layer for the first time to form a first opening region, injecting light boron on the silicon substrate 2 in the first opening region by taking the first photoresist layer as a mask to form the piezoresistor 22, removing the patterned first photoresist layer, and forming the first photoresist layer on the first surface again;

s4, patterning the first photoresist layer for the second time to form a second opening area, injecting concentrated boron on the silicon substrate 2 in the second opening area by taking the first photoresist layer as a mask to form an electric connection layer 23, namely a lead layer, and removing the patterned first photoresist layer;

s5, forming an insulating layer 3 on the lower surface of the silicon substrate 2, the piezoresistor 22 and the lead layer;

s6, forming a silicon bonding layer 4 on one side of the insulating layer 3, which is far away from the silicon substrate 2;

s7, forming a second photoresist layer on the upper surface of the silicon substrate 2;

s8, patterning the second photoresist layer to form a third opening area;

s9, etching part of silicon of the silicon substrate 2 corresponding to the third opening area to form a pressure cavity 20, and forming a pressure sensing diaphragm 21 in an area of the silicon substrate 2 opposite to the pressure cavity 20, wherein the depth of the pressure cavity 20 is smaller than the thickness of the silicon substrate 2, and then removing the patterned second photoresist layer;

s10, forming a third photoresist layer on the lower surface of the silicon bonding layer 4;

s11, patterning the third photoresist layer to form a gap, a fourth opening area facing the vacuum cavity 50 and a fifth opening area distributed along the periphery of the silicon bonding layer 4;

s12, etching the silicon bonding layer 4 to form an avoidance hole 40 facing the fourth opening area, a sixth opening area facing the fifth opening area and an isolation groove 402 separating the silicon bonding layer 4 into an isolation silicon layer 41 and an inner ring silicon layer 42 which are not in contact with each other, and finally, removing the patterned third photoresist layer;

s13, forming a fourth photoresist layer on the lower surface of the silicon bonding layer 4, the lower surface of the insulating layer 3 and the isolation groove 402;

s14, patterning the fourth photoresist layer to form a first contact hole opposite to the electric connection layer 23;

s15, etching the insulating layer 3 by adopting an RIE (reactive ion etching) process to form a second contact hole opposite to the first contact hole, wherein the second contact hole and the isolation silicon layer 41 are arranged at intervals, and the patterned fourth photoresist layer is removed;

s16, manufacturing a metal connecting piece 31 electrically connected with the lead layer in the second contact hole and on the periphery of the lower surface of the insulating layer 3, wherein the metal connecting piece 31 is positioned on the outer side of the isolating silicon layer 41 and the metal connecting piece 31 and the isolating silicon layer 41 are arranged at intervals;

s17, anodically bonding a first glass layer 1 on the upper surface of the silicon substrate 2, wherein a pressure hole 10 opposite to the pressure cavity 20 is formed in the first glass layer 1;

s18, anodically bonding a second glass layer 5 on the side, away from the insulating layer 3, of the silicon bonding layer 4, wherein the second glass layer 5, the silicon bonding layer 4 and the insulating layer 3 form a vacuum cavity 50 opposite to the pressure cavity 20;

s19, providing the substrate 6 with a mounting groove, the first metal PAD 62 and the lead 61, and coating an adhesive in the mounting groove of the substrate 6;

s20, forming a weldment 63 on the first metal PAD 62;

and S21, welding the welding piece 63 and the metal connecting piece 31, wherein the lower surface of the silicon bonding layer 4 is attached to the substrate 6, and the second glass layer 5 is bonded in the mounting groove.

The pressure sensor provided by the embodiment has a small volume, the optimal precision reaches one ten-thousandth, the optimal linearity reaches three hundred thousand, and the pressure sensor can be applied to a system level in the field of intelligent engineering machinery.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims (10)

1. The utility model provides a pressure sensor which characterized in that, including stacking in proper order:

the first glass layer is provided with pressure holes;

the silicon substrate is provided with a pressure cavity opposite to the pressure hole, a pressure sensing diaphragm capable of bearing external pressure is formed in the area of the silicon substrate opposite to the pressure cavity, and the silicon substrate is provided with a piezoresistor and an electric connection layer;

the insulating layer is formed on the silicon substrate, and a metal connecting piece is arranged on the insulating layer;

the silicon bonding layer is formed on the insulating layer and is arranged at intervals with the metal connecting piece;

and the second glass layer is fixed on the silicon bonding layer, and the second glass layer, the silicon bonding layer and the insulating layer form a vacuum cavity facing the pressure cavity.

2. The pressure sensor according to claim 1, further comprising a substrate, wherein the substrate is fixedly connected to the metal connecting member and has a mounting groove formed thereon, and an inner wall of the mounting groove is attached to the surface of the second glass layer.

3. The pressure sensor of claim 2, wherein the second glass layer is bonded within the mounting groove.

4. The pressure sensor as claimed in claim 2, wherein the substrate further has a conductive wire, a first metal PAD and a solder part, the conductive wire is electrically connected to the first metal PAD, the first metal PAD is formed on the surface of the substrate, the solder part is formed on the first metal PAD, the solder part is capable of being soldered to the metal connecting part, and the conductive wire is capable of transmitting an electrical signal to the outside.

5. The pressure sensor of claim 4, wherein the metal connection comprises a second metal PAD and a metal connection layer electrically connected, the second metal PAD extending through the insulating layer, the metal connection layer formed on a surface of the insulating layer and electrically connected to the solder.

6. The pressure sensor of claim 5, wherein the silicon bonding layer is provided with an avoiding hole and an isolating groove, the avoiding hole is right opposite to the vacuum cavity, the isolating groove separates the silicon bonding layer into an isolating silicon layer and an inner ring silicon layer which are not in contact with each other, the inner ring silicon layer is located on the inner side of the isolating silicon layer, and the isolating silicon layer is located on the inner side of the metal connecting piece, the first metal PAD and the welding piece.

7. A pressure sensor as claimed in claim 1, wherein the piezoresistor is arranged directly opposite an edge of the pressure chamber.

8. The pressure sensor of claim 1, wherein the electrical connection layer is a lead layer, the number of the piezoresistors is four, and the four piezoresistors are connected through the electrical connection layer to form a wheatstone bridge.

9. The pressure sensor of claim 1, wherein the insulating layer comprises at least one of a silicon oxide layer, an aluminum oxide layer, and a silicon nitride layer.

10. The pressure sensor of claim 1, wherein the silicon bonding layer is a polysilicon layer or an amorphous silicon layer.

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