CN110132395A - A MEMS vector hydrophone with overload protection structure - Google Patents

Abstract

The invention discloses a MEMS vector hydrophone with an overload protection structure, belonging to the technical field of MEMS sensors and vector hydrophones. It includes a silicon-based sensing module and a glass-based overload protection module, wherein a rigid lightweight column is arranged on the silicon-based sensing module, and the glass-based overload protection module is used to limit the movement range of the rigid lightweight column. The invention solves the problem that the current co-vibration vector hydrophone is prone to damage to sensitive elements when it is subjected to a large impact from the outside, and at the same time solves the problem of installation limitation and easy bonding of the bionic MEMS vector hydrophone cilia-type sensing element The problem of overflow is an important improvement to the prior art.

Description

A MEMS vector hydrophone with overload protection structure

technical field

The invention relates to the technical field of MEMS sensors and vector hydrophones, in particular to a MEMS vector hydrophone with an overload protection structure.

Background technique

At present, in the field of vector hydrophones, it is mainly divided into vector hydrophones based on the principle of differential pressure and co-vibration vector hydrophones based on the principle of inertia. The vector hydrophone based on the principle of differential pressure is limited by the principle of induction, and is mainly used for the detection of high-frequency acoustic vector signals. It is gradually replaced by the co-vibration vector hydrophone based on the principle of inertia.

The co-vibration vector hydrophone based on the principle of inertia is generally suspended and installed by rubber bands and springs. Under the excitation of underwater sound waves, it can move with the water particle at the same frequency and amplitude. The vibration signal is sensed, and then the detection of the acoustic vector signal is completed. According to the different internal integrated vibration sensing components, the co-vibration vector hydrophone based on the principle of inertia can generally be subdivided into displacement type, velocity type, acceleration type, etc.

However, due to the internal integration of movable components in the co-vibration vector hydrophone based on the principle of inertia, its reliability is greatly reduced. If it is hit or dropped during use and transportation, it is easy to cause vector hydrophone The damage to the sensitive components inside the hydrophone will lead to the failure of the vector hydrophone.

Contents of the invention

In view of this, the present invention proposes a MEMS vector hydrophone with an overload protection structure, which can improve the seismic performance and reliability of the MEMS vector hydrophone.

In order to achieve the above object, the technical scheme that the present invention takes is:

A MEMS vector hydrophone with an overload protection structure, which includes a stacked silicon-based sensing module 1 and a glass-based overload protection module 2, the silicon-based sensing module 1 is provided with a sensor for sensing two-dimensional directional sound vector signals A rigid lightweight column 3 , the glass-based overload protection module 2 covers the rigid lightweight column 3 so as to limit the movement range of the rigid lightweight column 3 .

Optionally, the silicon-based sensing module 1 includes a cross-shaped sensitive fixed beam 101, a silicon-based frame 102, and a limit cylinder 103; the cross-shaped sensitive fixed beam 101 is connected by a central disc 1011 and four sensor Composed of arms 1012, the central connection disc 1011 is located at the center of the silicon-based sensing module 1, four sensing arms 1012 are located around the central connection disc 1011 in a 90° orthogonal manner, and one end of the four sensing arms 1012 is connected to the center circle The disk 1011 is connected, and the other end is connected with the silicon-based frame 102; the limit cylinder 103 is located below the central connection disk 1011, and the geometric center coincides with the geometric center of the central connection disk 1011; each sensing arm 1012 has There are two piezoresistors 105, namely the center piezoresistor 1051 and the edge piezoresistor 1052, the center piezoresistor 1051 is close to the connection position between the sensing arm 1012 and the central connection disc 1011, and the edge piezoresistor 1052 is close to the sensing arm 1012 and the connection position of the silicon-based frame 102; the silicon-based frame 102 is provided with an electric lead-out pad 107, and the piezoresistor 105 is electrically connected with the electric lead-out pad 107 by using a metal connection lead 106; the rigid light column body 3 is located at In the limiting cylinder 103 , the bottom of the rigid and lightweight cylinder 3 is connected to the back of the central connecting disc 1011 through adhesive 104 .

Optionally, the center of the glass-based overload protection module 2 is provided with a coaxial disc-shaped movement cavity 201 and a cylindrical limit cavity 202, and the radius of the disc-shaped movement cavity 201 is larger than that of the cylindrical limit cavity. The radius of the cavity 202, the cylindrical limit cavity 202 is directly connected with the disc-shaped motion cavity 201 and runs through the glass-based overload protection module 2, and the rigid light column 3 passes through the disc-shaped motion cavity 201 and the The cylindrical limiting cavity 202 is exposed outside the glass-based overload protection module 2 , and the radius of the cylindrical limiting cavity 202 is larger than the radius of the rigid and lightweight cylinder 3 .

Optionally, the material of the rigid and lightweight cylinder 3 is a photosensitive resin with a density ranging from 1 to 1.2 g/cm ³ .

Optionally, the radius of the central connection disc 1011 is 400 μm; the length of the sensing arm 1012 is 100 μm to 1000 μm, and the width is 80 μm to 150 μm; the thickness of the central connection disc 1011 is the same as that of the sensing arm 1012 , with a thickness ranging from 10 μm to 40 μm; the side length of the silicon-based frame 102 is 4800 μm, and the thickness is 400 μm; the outer diameter of the limiting cylinder 103 is 500 μm, the inner diameter is 300 μm, and the height is 400 μm.

Optionally, the thickness of the glass-based overload protection module 2 is 600 μm, and the side length is 4800 μm; the radius of the disc-shaped motion cavity 201 is 400 μm, and the height is 50-100 μm; the cylindrical limiting cavity The radius of 202 is 300 μm.

Optionally, the rigid and lightweight cylinder 3 has a radius of 80-125 μm and a height of 4000-6000 μm.

Optionally, the bonding glue 104 is ultraviolet exposure glue.

The present invention has following beneficial effects:

1. The present invention designs a new MEMS vector hydrophone chip structure based on the principle of cilia induction. The chip comes with a rigid light cylinder overload protection structure, which can limit the movement range of the rigid light cylinder, and then Protects the sensitive arm connected to the rigid lightweight column from breakage damage caused by excessive impact.

2. The MEMS vector hydrophone with overload protection structure designed by the present invention has the induction principle that under the condition of sound waves under water, the rigid light cylinder will vibrate with the water particle at the same frequency and amplitude under the sound wave excitation, and then Drive the cross-shaped sensitive fixed beam connected with the rigid light column by adhesive to produce torsional movement, causing the sensitive arm to deform, and the piezoresistor set on the sensitive arm of the cross-shaped sensitive fixed beam is subjected to compressive stress/tension Under the action of stress, the resistance of the piezoresistor will change, and then the Wheatstone bridge composed of piezoresistors is used to complete the detection of the acoustic vector signal of the sound wave, and complete the conversion of the acoustic vector signal to the electrical signal.

In short, the traditional vector sensor can not only sense the acoustic vector signal, but also the vibration signal transmitted from the external environment. During use and transportation, it is inevitable that the vector hydrophone will be affected to a greater extent due to collisions and drops. When the vibration amplitude exceeds the acceptable range of the internal sensitive components, it is very easy to damage the sensitive components, which in turn causes damage to the vector hydrophone. However, the vector hydrophone designed by the present invention has a glass-based overload protection module inside the chip, and when its sensitive element (rigid light column + cross-shaped sensitive solid support beam) is subjected to excessive impact and produces large deformation , the glass-based overload protection module inside the chip will limit the movement amplitude of the rigid light column, limiting the excessive swing of the rigid light column, which will cause the sensing arm of the cross-shaped sensitive fixed beam to break and damage , It can effectively protect the sensitive components of the vector hydrophone under the action of large impact and vibration, and improve the application reliability and scope of application of the vector hydrophone.

Description of drawings

Fig. 1 is a schematic structural diagram of a MEMS vector hydrophone in an embodiment of the present invention.

Fig. 2 is a top view of the silicon-based sensing module in Fig. 1 .

FIG. 3 is a side view of the silicon-based sensing module in FIG. 1 .

FIG. 4 is a top view of the glass-based overload protection module in FIG. 1 .

FIG. 5 is a side view of the glass-based overload protection module in FIG. 1 .

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

A MEMS vector hydrophone with an overload protection structure, which includes a silicon-based sensing module for detecting two-dimensional directional sound vector signals, and is arranged under the silicon-based sensing module to implement overload protection for the sensitive structure of the silicon-based sensing module The glass-based overload protection module, in which the silicon-based sensing module is equipped with a rigid lightweight cylinder for sensing two-dimensional directional sound vector signals, the glass-based overload protection module controls the movement range of the rigid lightweight cylinder through the limit to achieve In the case of a large impact, due to the excessive swing of the rigid light column, the chip is damaged due to the breakage of the cross-shaped sensitive fixed beam on the silicon-based sensing module; the silicon-based sensing module includes a silicon-based frame, a cross-shaped sensitive fixed beam , limit cylinder, adhesive glue, piezoresistor, metal connection lead wire and electrical lead-out pad; the cross-shaped sensitive fixed support beam is composed of a central connection disc and 4 sensing arms, and the central connection disc is located in the silicon-based sensing module In the center, the four sensing arms are located around the central connecting disc in a 90° orthogonal direction. One end of the four sensing arms is connected to the central connecting disc, and the other end is connected to the silicon-based frame. The limit cylinder is located on the central connecting disc. Below and the geometric center coincides with the geometric center of the central connection disc, the adhesive is located in the limit cylinder, and is connected to the back of the central connection disc; two piezoresistors are set on each sensing arm, respectively for the central pressure The varistor and the edge varistor, the central varistor is close to the connection position between the sensing arm and the central connection disc, and the edge varistor is close to the connection position between the sensing arm and the silicon-based frame; The resistor uses the metal connecting lead and the electric lead-out pad to realize the electric lead connection; the glass-based overload protection module is provided with a disc-shaped movement cavity and a cylindrical limit cavity, and the disc-shaped movement cavity and the cylindrical limit cavity are located at Inside the glass-based overload protection module, the geometric centers of the three coincide, the disc-shaped motion cavity is located above the cylindrical limit cavity, and the disc-shaped motion cavity and the cylindrical limit cavity are directly connected through the glass-based overload protection module; The rigid and lightweight cylinder is set in the limit cylinder, and the bottom is connected to the back of the central connection disc of the silicon-based sensing module with adhesive glue. The rigid and lightweight cylinder penetrates the glass-based overload protection module as a whole, and the top is located External to the overload protection module.

Further, the rigid and lightweight cylinder is realized with a photosensitive resin that is approximately equal to the density of seawater, and the density ranges from 1 to 1.2g/cm3.

The radius of the central connection disc is 400 μm, the length of the sensing arm is 100 μm~1000 μm, and the width is 80 μm~150 μm. The thickness of the central connection disc is the same as that of the sensing arm, and the thickness range is 10 μm~40 μm; the side length of the silicon-based frame is 4800 μm, and the thickness is 400 μm ; The outer diameter of the limiting cylinder is 500 μm, the inner diameter is 300 μm, and the height is 400 μm.

The thickness of the glass-based overload protection module is 600 μm, and the side length is 4800 μm; the radius of the disc-shaped motion cavity is 400 μm, and the height is 50-100 μm; the radius of the cylindrical limiting cavity is 300 μm, and the height runs through the entire base of the glass-based overload protection module.

Rigid and lightweight cylinders have a radius of 80-125 μm and a height of 4000-6000 μm.

The bonding glue is UV exposure glue, which can be cured quickly by UV exposure.

Compared with the traditional bionic MEMS vector hydrophone based on the principle of cilia sensing, this hydrophone is equipped with a glass-based overload protection module on the back of the silicon-based sensing module, and a disc-shaped motion cavity is arranged in the glass-based overload protection module and a cylindrical limiting cavity, the rigid and lightweight cylinder passes through the disc-shaped motion cavity of the glass-based overload protection module and the cylindrical limiting cavity extends to the outside of the glass-based overload protection module for sensing sound wave information, and the rigid and light A certain gap is reserved between the mass cylinder and the cylindrical limiting cavity so that the rigid light cylinder can realize free vibration after being excited by the sound wave, and when it is subjected to a large external impact, the movement range of the rigid light cylinder can be limited to prevent Excessive swing amplitude leads to fracture and damage of the sensing arm of the cross-shaped sensitive fixed beam.

Specifically, as shown in Figures 1 to 5, a MEMS vector hydrophone with an overload protection structure includes a silicon-based sensing module 1 for detecting two-dimensional directional sound vector signals, and a silicon-based sensing module 1 1 below is a glass-based overload protection module 2 for overload protection of the sensitive structure of the silicon-based sensing module 1, wherein the silicon-based sensing module 1 is provided with a rigid and lightweight column 3 for sensing two-dimensional directional sound vector signals, and the glass-based sensing module 1 The overload protection module 2 controls the range of motion of the rigid lightweight column 3 by limiting the limit so that under the condition of a large impact, the cross-shaped sensitive fixed beam on the silicon-based sensing module 1 will be caused by the excessive swing of the rigid lightweight column 3. The fracture of 101 causes chip damage.

Both the silicon-based sensing module 1 and the glass-based overload protection module 2 can be realized by MEMS technology, which realizes chipping and miniaturization of the acoustic vector sensing element.

Among them, the implementation process of the silicon-based sensing module 1 is as follows:

1) Prepare SOI substrate, substrate specifications: SOI substrate is a 6-inch standard substrate, including a silicon substrate of 600 μm, an oxide layer (BOX layer) of 1 μm and a top silicon base layer of 10 μm to 40 μm;

2) Preparation of varistors, the main process steps are: using thermal oxidation process to prepare SiO ₂ layer; using photolithography and RIE process to prepare light boron piezoresistive pattern; using ion implantation process to implement light boron implantation to form P-type varistor; Using photolithography and RIE technology to prepare boron-concentrated piezoresistive patterns; using ion implantation technology to implement concentrated boron implantation to form varistor electrical lead-out areas; high-temperature annealing to implement varistor diffusion advancement;

3) Metal layer preparation, the main process steps are: use LPCVD process to grow SiO ₂ layer; use LPCVD process to grow SiN _x layer; use photolithography process to lithographically lead out contact holes; use RIE process to etch SiN _x layer and SiO ₂ on the front side Layer, open the contact window of the varistor concentrated boron implantation area and the electrical lead-out area; Li uses photolithography to prepare metal lead patterns; sputters Cr/Au; uses Lift-off process to form metal lead lines;

4) Back cavity etching, the main process steps are: use PECVD process to prepare SiO ₂ layer on the back of SOI silicon substrate _; Etch the SOI substrate silicon-based substrate until it reaches the self-stop of the BOX layer;

5) Front pattern etching, the main process steps are: using photolithography process to lithography the front structure pattern; using RIE process to etch the front SiO ₂ layer and SiN _x layer; using ICP process to etch the front top silicon base layer until reaching the BOX layer. Stop; use the RIE process to etch the BOX layer on the front side; complete the preparation of the silicon-based sensing module 1 .

The realization process of the glass-based overload protection module 2 is as follows:

1) Prepare the glass substrate, substrate specifications: the glass substrate is a 6-inch standard substrate with a thickness of 600 μm;

2) The preparation of the disc-shaped moving cavity, the main process steps are: use the photolithography process to complete the pattern preparation of the disc-shaped moving cavity; use the DRIE process to etch the glass substrate to a depth of 50-100 μm;

3) The preparation of the cylindrical limiting cavity, the main process steps are: using laser etching technology to etch the glass substrate in the center of the disc-shaped moving cavity pattern until it penetrates to complete the preparation of the cylindrical limiting cavity; Preparation of base overload protection module 2.

The bonding and packaging process between the silicon-based sensing module 1 and the glass-based overload protection module 2 is as follows: use the silicon-glass electrostatic bonding process to realize the close connection between the silicon-based sensing module 1 and the glass-based overload protection module 2, and complete the two modules package between.

The installation process of the rigid and lightweight cylinder 3 is as follows: use a precision dispenser to dispens glue through the cylindrical limiting cavity of the glass-based overload protection module 2, place adhesive 104 in the limiting cylinder 103; Clamp and fix the top of the rigid lightweight cylinder 3, move the rigid lightweight cylinder 3 to the top of the encapsulated glass-based overload protection module 2 through the mechanical movement arm, and use a high-magnification microscope to realize the precise positioning of the rigid lightweight cylinder 3; up and down Move the rigid lightweight cylinder 3 so that its lower end passes through the glass-based overload protection module 2 until it reaches the bottom of the limiting cylinder 103 and contacts the adhesive 104; irradiating with an ultraviolet lamp completes the curing of the adhesive 104;

So far, the process preparation of the MEMS vector hydrophone of this embodiment is completed.

In a word, the present invention proposes a MEMS vector hydrophone with an overload protection structure, which can solve the problem that the current co-vibration vector hydrophone is prone to damage to sensitive components under the condition of a large impact from the outside, and also solves the problem of The installation limit of the cilium-type sensing element of the bionic MEMS vector hydrophone and the problem that the adhesive glue is easy to overflow.

It should be noted that the above descriptions are only individual specific implementations of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. a kind of MEMS vector hydrophone for having overcurrent protection structure, which is characterized in that including stacked silicon substrate sensing module (1) and glass base overload protection module (2) it, is provided on the silicon substrate sensing module (1) for perceiving two-dimensional directional acoustic vector The rigidity light cylinder (3) of signal, the glass base overload protection module (2) entangle the rigidity light cylinder (3) to limit The motion range of rigidity light cylinder (3) processed.

2. a kind of MEMS vector hydrophone for having overcurrent protection structure according to claim 1, which is characterized in that described Silicon substrate sensing module (1) includes cross sensitive clamped beam (101), silicon substrate frame (102) and limiting cylinder (103)；Described ten Font sensitivity clamped beam (101) is made of center clutch disk (1011) and 4 sensing arms (1012), the center clutch disk (1011) it is located at the center of silicon substrate sensing module (1), 4 sensing arms (1012) are located at center clutch disk with 90 ° of orthogonal manners (1011) surrounding, 4 sensing arm (1012) one end are connect with center clutch disk (1011), the other end and silicon substrate frame (102) it connects；The limiting cylinder (103) is located at the lower section of center clutch disk (1011), and geometric center is connect with center The geometric center of disk (1011) is overlapped；2 varistors (105) are provided on each sensing arm (1012), respectively in Heart varistor (1051) and edge varistor (1052), center varistor (1051) is close to sensing arm (1012) and center The link position of clutch disk (1011), edge varistor (1052) is close to sensing arm (1012) and silicon substrate frame (102) Link position；It is provided with electricity on silicon substrate frame (102) and draws pad (107), varistor (105) utilizes metal connecting lead wire (106) pad (107) are drawn with electricity to be electrically connected；The rigidity light cylinder (3) is located among limiting cylinder (103), and rigidity is light The bottom of matter cylinder (3) is connect by adhesive glue (104) with the back side of center clutch disk (1011).

3. a kind of MEMS vector hydrophone for having overcurrent protection structure according to claim 1, which is characterized in that described The center of glass base overload protection module (2) is equipped with coaxial disc movement cavity (201) and cylindrical limit cavity (202), the radius of disc movement cavity (201) is greater than the radius of cylindrical limit cavity (202), cylinder limit cavity (202) it is connected directly with disc movement cavity (201) and runs through glass base overload protection module (2), the rigidity light column Body (3) sequentially passes through disc movement cavity (201) and cylindrical limit cavity (202) and is exposed to glass base overload protection mould The outside of block (2), the radius of cylinder limit cavity (202) are greater than the radius of rigidity light cylinder (3).

4. a kind of MEMS vector hydrophone for having overcurrent protection structure according to claim 1, which is characterized in that described It is 1 ~ 1.2g/cm that the material of rigidity light cylinder (3), which is density range,³Photosensitive resin.

5. a kind of MEMS vector hydrophone for having overcurrent protection structure according to claim 2, which is characterized in that described The radius of center clutch disk (1011) is 400 μm；The length of the sensing arm (1012) is 100 μm ~ 1000 μm, width 80 μm~150μm；The center clutch disk (1011) is of uniform thickness with the sensing arm (1012), and thickness range is 10 μm ~ 40 μm；The side length of the silicon substrate frame (102) is 4800 μm, with a thickness of 400 μm；The outer diameter of the limiting cylinder (103) is 500 μ M, internal diameter are 300 μm, are highly 400 μm.

6. a kind of MEMS vector hydrophone for having overcurrent protection structure according to claim 3, which is characterized in that described Glass base overload protection module (2) with a thickness of 600 μm, side length is 4800 μm；The radius of disc movement cavity (201) It is 400 μm, is highly 50 ~ 100 μm；The radius of cylindrical limit cavity (202) is 300 μm.

7. a kind of MEMS vector hydrophone for having overcurrent protection structure according to claim 1, which is characterized in that described The radius of rigidity light cylinder (3) is 80 ~ 125 μm, is highly 4000 ~ 6000 μm.

8. a kind of MEMS vector hydrophone for having overcurrent protection structure according to claim 2, which is characterized in that described Adhesive glue (104) is uv-exposure glue.