CN211263740U - Magnetic field/acceleration integrated sensor - Google Patents

Abstract

The utility model discloses a magnetic field/acceleration integrated sensor, the sensor comprises a magnetic field sensor and an acceleration sensor arranged on the same chip, the magnetic sensitive unit of the magnetic field sensor comprises a silicon magnetic triode and a Hall magnetic field sensor, wherein the Hall magnetic field The sensor uses in-situ doped nano-silicon thin film nc‑Si:H(n ⁺ ) as the magnetic sensitive layer, and the sensitive unit of the acceleration sensor is mainly in-situ doped nano-polysilicon thin film resistor, which can realize simultaneous detection of three-dimensional magnetic field and three-axis acceleration. Measurement. The utility model completes the fabrication of the integrated sensor chip on the SOI wafer device layer based on the microelectronic machining technology, and realizes the chip packaging through the bonding process and the inner lead pressure welding technology, and has the characteristics of small size and easy mass production.

Description

A magnetic field/acceleration integrated sensor

technical field

The utility model relates to the technical field of sensors, in particular to a single-chip integrated sensor for simultaneous detection of multiple physical quantities and multiple parameters, in particular to a magnetic field/acceleration integrated sensor.

Background technique

With the rapid development of science and technology and application requirements, sensor technology has received much attention. Today, it has developed from a single sensitive unit to an integrated sensor that can measure multiple physical quantities and directions at the same time, and is widely used in modern industry, automotive electronics , aerospace, deep-sea exploration and other fields.

By analyzing the measurement principles of the three-dimensional magnetic field in space and acceleration in three directions, the results show that the sensitive elements have great differences in the sensitive mechanism, the selection of the conductivity type of the substrate material, and the fabrication process. At present, the magnetic field sensors that can be used for integration mainly include Hall magnetic field sensors, magneto-sensitive diodes, magneto-sensitive triodes, split-leakage field effect transistors (MAGFETs), etc. Considering the main factors affecting the magnetic sensitivity characteristics of magnetic field sensors, the integrated The magnetic field sensor preferably has a single-crystal silicon substrate of p-type conductivity; by analyzing the characteristics of the piezoresistive acceleration sensor, preferably the single-crystal silicon substrate is of n-type conductivity. In the prior art, there is often an incompatibility problem in the process of manufacturing an integrated chip, which makes it difficult to integrate a three-dimensional magnetic field sensor and a three-axis acceleration sensor.

Therefore, it is necessary to provide a monolithic integrated magnetic field/acceleration sensor, which can realize the simultaneous measurement of three-dimensional magnetic field and three-axis acceleration, and has good compatibility.

Utility model content

In order to overcome the above-mentioned problems, the inventors have carried out keen research and found that a monolithic integrated magnetic field/acceleration sensor is fabricated on an SOI wafer (device layer p-type high-resistance Si, resistivity ρ≥100Ω·cm), using a three-dimensional structure. Silicon magneto-sensitive triode and Hall magnetic field sensor with phosphorus-doped nano-silicon thin film nc-Si:H(n ⁺ ) as magnetic sensitive layer are used as sensitive unit of magnetic field sensor, and boron-doped nano-polysilicon thin film resistor is used as sensitive element of acceleration sensor, Simultaneous measurement of three-dimensional magnetic field and three-axis acceleration can be realized, thereby completing the utility model.

Specifically, the purpose of the present utility model is to provide a magnetic field/acceleration integrated sensor, wherein the sensor includes a magnetic field sensor and an acceleration sensor arranged on the same chip, so as to realize the simultaneous measurement of three-dimensional magnetic field and three-axis acceleration;

The magnetic field/acceleration integrated sensor takes an SOI sheet as a substrate, and the SOI sheet includes a device layer 1, a supporting silicon 2 and a first silicon dioxide layer 3;

Wherein, the thickness of the device layer 1 is 20-50 μm, and the thickness of the supporting silicon 2 is 420-550 μm;

The magnetic field sensor includes four silicon magneto-sensitive triodes with a three-dimensional structure and a Hall magnetic field sensor H, which are arranged on the device layer 1.

The four silicon magneto-sensitive triodes are combined in pairs to form two magneto-sensitive units, which are respectively used to detect the magnetic field in the x-axis direction and the y-axis direction;

The Hall magnetic field sensor H is used to detect the magnetic field in the z-axis direction;

A suspended structure is etched at the middle position of the acceleration sensor, and the suspended structure includes a mass block at the center position and four double L-shaped beams located on both sides of the mass block;

There are two mass blocks, which are respectively a first mass block m ₁ and a second mass block m ₂ ;

Each of the double L-shaped beams includes two single L-shaped beams, and the four double L-shaped beams have a total of eight single L-shaped beams, which are the first single L-shaped beam L ₁ and the second single L-shaped beam L ₂ . , the third single L-shaped beam L ₃ , the fourth single L-shaped beam L ₄ , the fifth single L-shaped beam L ₅ , the sixth single L-shaped beam L ₆ , the seventh single L-shaped beam L ₇ and the eighth single L-shaped beam L 6 Profile beam L ₈ .

The beneficial effects of the present invention include:

(1) The magnetic field/acceleration integrated sensor provided by the utility model can realize the simultaneous measurement of three-dimensional magnetic field and three-axis acceleration in space;

(2) For the magnetic field/acceleration integrated sensor provided by the present utility model, the SOI wafer whose device layer is p-type <100> crystal orientation high-resistance monocrystalline silicon is selected as the substrate, and the Hall magnetic field sensor in the magnetic sensitive unit of the magnetic field sensor is selected as the substrate. The in-situ doped nano-silicon thin film nc-Si:H(n ⁺ ) is used as the magnetic sensitive layer, and the sensitive unit of the acceleration sensor is mainly the in-situ doped nano-polysilicon thin film resistor, which solves the problem of two different physical quantity measurement sensitive unit substrate conduction. different types of puzzles;

(3) The integrated process method of the magnetic field/acceleration integrated sensor provided by the present utility model realizes the fabrication of the magnetic field/acceleration sensor chip based on the MEMS technology and the in-situ doping CVD method, and adopts the bonding process and the inner lead pressure welding technology. To achieve chip packaging, it has the characteristics of small size and easy mass production.

Description of drawings

FIG. 1 shows a schematic view of the front structure of a magnetic field/acceleration integrated sensor according to a preferred embodiment of the present invention;

FIG. 2 shows a schematic view of the back structure of a magnetic field/acceleration integrated sensor according to a preferred embodiment of the present invention;

3 shows an equivalent circuit diagram of a magnetic field sensor according to a preferred embodiment of the present invention;

FIG. 4 shows an equivalent circuit diagram of an acceleration sensor according to a preferred embodiment of the present invention;

5-a to 5-e show the integrated manufacturing process flow chart of the magnetic field/acceleration integrated sensor of the present invention;

Figures 6-a to 6-c show experimental characteristic curves of the magnetic field sensor along the x-axis, y-axis and z-axis directions of a preferred embodiment of the present invention;

FIG. 7 shows the experimental characteristic curve of the acceleration sensor according to a preferred embodiment of the present invention.

Description of reference numbers:

1-device layer; 2-support silicon; 3-first silicon dioxide layer; 4-second silicon dioxide layer; 5-isolation trench; 6-metal aluminum layer; H-Hall magnetic field sensor; SMST1-first silicon magneto-sensitive triode; SMST2-second silicon magneto-sensitive triode; SMST3-third silicon magneto-sensitive triode; SMST4-fourth silicon magneto-sensitive triode; B ₁ -first base; B ₂ - second base; B ₃ - third base; B ₄ - fourth base; C ₁ - first collector; C ₂ - second collector; C ₃ - third collector; C _{4 -} fourth collector; An emitter; E ₂ - the second emitter; E ₃ - the third emitter; E ₄ - the fourth emitter; R _L1 - the first collector load resistance; R _L2 - the second collector load resistance; R _L3 - third collector load resistance; R _L4 - fourth collector load resistance; V ₁ - x-axis first output voltage; V ₂ - x-axis second output voltage; V ₃ - y-axis first output voltage; V ₄ -y-axis second output voltage; V _DD - power supply; GND - ground; I _H1 - first control current pole; I _H2 - second control current pole; V _H1 - first Hall output terminal; V _H2 - second Hall output terminal; R _H1 - the first equivalent resistance; R _H2 - the second equivalent resistance; R _H3 - the third equivalent resistance; R _H4 - the fourth equivalent resistance; m ₁ - the first mass; m ₂ - second mass; L ₁ - first single L-beam; L ₂ - second single L-beam; L ₃ - third single L-beam; L ₄ - fourth single L-beam; L ₅ - Fifth single L-beam; L6 - _sixth single L-beam; _L7 - seventh single L-beam; L8 - _eighth single L-beam; _{L9 -} first intermediate beam; L10 - second Middle beam; R _x1 - the first varistor in the x-axis direction; R _x2 - the second varistor in the x-axis direction; R _x3 - the third varistor in the x-axis direction; R _x4 - the fourth varistor in the x-axis direction ; R _y1 - the first varistor in the y-axis direction; R _y2 - the second varistor in the y-axis direction; R _y3 - the third varistor in the y-axis direction; R _y4 - the fourth varistor in the y-axis direction; R _z1 - the first varistor in the z-axis direction; R _z2 - the second varistor in the z-axis direction; R _z3 - the third varistor in the z-axis direction; R _z4 - the fourth varistor in the z-axis direction; V _xout1 - X-axis first output voltage; V _xout2 -x-axis second output voltage; V _yout1 -y-axis first output voltage; V _yout2 -y-axis second output voltage; V _zout1 -z-axis first output voltage; V _zout2 - The second output voltage of the z-axis; △R- the relative change of the resistance value of the chip when the chip is affected by external acceleration or magnetic field.

Detailed ways

The present utility model will be described in further detail below through the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer. Therein, although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

The utility model provides a magnetic field/acceleration integrated sensor, as shown in FIG. 1 , the sensor includes a magnetic field sensor and an acceleration sensor integrated on the same chip to realize simultaneous measurement of three-dimensional magnetic field and three-axis acceleration.

According to a preferred embodiment of the present invention, the magnetic field/acceleration integrated sensor uses an SOI sheet as a substrate, and the SOI sheet includes a device layer 1 and a supporting silicon 2 .

The inventors of the present invention have found that, compared with those fabricated on traditional silicon wafers, devices fabricated on SOI wafers have smaller parasitic capacitances, which can improve the speed of the devices.

In a further preferred embodiment, the device layer 1 is p-type <100> crystal orientation high-resistance single crystal silicon, and the thickness of the device layer 1 is 20-50 μm, preferably 25-35 μm.

Wherein, the resistivity ρ of the device layer is greater than 100Ω·cm.

In a further preferred embodiment, the supporting silicon 2 is p-type <100> crystal orientation high-resistance single crystal silicon, and its thickness is 420-550 μm, preferably 450-525 μm, and more preferably 475-500 μm.

Preferably, a first silicon dioxide layer 3 is disposed between the device layer 1 and the supporting silicon 2 , and the thickness of the first silicon dioxide layer 3 is 500 nm˜800 nm.

The inventor of the present invention has found that, in the process of monolithically integrating a three-dimensional magnetic field sensor and a three-axis acceleration sensor, a monolithic integrated magnetic field/acceleration sensor is fabricated on an SOI wafer whose device layer is p-type <100> crystal orientation high-resistance single-crystal silicon. , can realize the simultaneous measurement of three-dimensional magnetic field and three-axis acceleration.

More preferably, a second silicon dioxide layer 4 is provided on the upper surface of the device layer 1, and the thickness of the second silicon dioxide layer 4 is 400nm˜600nm.

According to a preferred embodiment of the present invention, as shown in FIG. 1 , the magnetic field sensor includes four silicon magneto-sensitive triodes in a three-dimensional structure and a Hall magnetic field sensor H, which are arranged on the device layer 1 , wherein,

The four silicon magneto-sensitive triodes are combined in pairs to form two magneto-sensitive units, which are respectively used to detect the magnetic field in the x-axis direction and the y-axis direction;

The Hall magnetic field sensor H is used to detect the magnetic field in the z-axis direction.

In a further preferred embodiment, the Hall magnetic field sensor is arranged at the center position of the magnetic field sensor, and the four silicon magneto-sensitive triodes are arranged at the edge position of the magnetic field sensor.

Among them, p-type high-resistance single crystal silicon is used as the device layer and substrate, which is beneficial to improve the sensitivity of the magnetic field sensor.

In a further preferred embodiment, the four silicon magneto-sensitive triodes are respectively a first silicon magneto-sensitive triode SMST1, a second silicon magneto-sensitive triode SMST2, a third silicon magneto-sensitive triode SMST3 and a fourth silicon magneto-sensitive triode SMST4 ,

Wherein, the first silicon magneto-sensitive triode SMST1 and the second silicon magneto-sensitive triode SMST2 are symmetrically arranged along the x-axis of the magnetic field sensor on both sides of the center of the three-dimensional magnetic field sensor chip,

The third silicon magneto-sensitive triode SMST3 and the fourth silicon magneto-sensitive triode SMST4 are symmetrically arranged along the y-axis of the magnetic field sensor on both sides of the center of the three-dimensional magnetic field sensor chip.

Preferably, the first silicon magneto-sensitive triode SMST1 and the second silicon magneto-sensitive triode SMST2 are arranged in the opposite magnetic sensitivity directions of the y-axis, and the third silicon magneto-sensitive triode SMST3 and the fourth silicon magneto-sensitive triode SMST4 are opposite to the x-axis Magnetic sensitivity direction setting.

According to a preferred embodiment of the present invention, a base region and a collector region are also formed on the upper surface of the device layer 1 , and an emission region is formed on the lower surface of the device layer 1 .

In a further preferred embodiment, a metal Al layer 6 is evaporated on the surfaces of the base region, the collector region and the emitter region to form the base, collector and emitter of the silicon magneto-transistor, respectively.

Wherein, as shown in FIG. 1 , a first base B ₁ and a first collector C ₁ of a first silicon magneto-sensitive triode SMST1 are respectively fabricated on the upper surface of the device layer 1 , and a second The base electrode B ₂ and the second collector electrode C ₂ , the third base electrode B ₃ and the third collector electrode C ₃ of the third silicon magneto-sensitive triode SMST3, the fourth base electrode B ₄ and the third electrode of the fourth silicon magneto-sensitive triode SMST4 Four collectors C ₄ .

As shown in FIG. 2 , a first emitter E ₁ of a first silicon magneto-sensitive triode SMST1 , a second emitter E ₂ of a second silicon magneto-sensitive triode SMST2 , and a third silicon magneto-sensitive triode SMST2 are fabricated on the lower surface of the support silicon 2 . The third emitter E ₃ of the magneto-sensitive triode SMST3 and the fourth emitter E ₄ of the fourth silicon magneto-sensitive triode SMST4 .

In a further preferred embodiment, a collector load resistor is fabricated on the upper surface of the device layer 1 and on one side of the collector of the silicon magneto-transistor.

Wherein, as shown in FIG. 1 , a first collector load resistor R _L1 is formed on the side of the first collector C ₁ of the first silicon magneto-sensitive triode SMST1, and the second collector C ₂ of the second silicon magneto-sensitive triode SMST2 A second collector load resistor R _L2 is fabricated on one side, a third collector load resistor R _L3 is fabricated on one side of the _third collector C3 of the third silicon magneto-sensitive triode SMST3, and a fourth collector of the fourth silicon magneto-sensitive triode SMST4 is fabricated. A fourth collector load resistor R _L4 is formed on one side of the collector C ₄ .

Preferably, the four collector load resistors are all n ^- type doped.

According to a preferred embodiment of the present invention, as shown in FIGS. 1 and 3 , one end of the first collector _C1 of the first silicon magneto-sensitive triode SMST1 is connected to the first collector load resistor R _L1 , and when the connection is made where the x-axis first output voltage V ₁ is formed,

One end of the second collector C ₂ of the second silicon magneto-sensitive triode SMST2 is connected to the second collector load resistor R _L2 , and a second x-axis output voltage V ₂ is formed at the connection.

In a further preferred embodiment, the first base B ₁ , the second base B ₂ , the other end of the first collector load resistor R _L1 and the other end of the second collector load resistor R _L2 are commonly connected to a power source _VDD .

Wherein, the emitter of the first silicon magneto-sensitive triode SMST1 and the emitter of the second silicon magneto-sensitive triode SMST2 are commonly grounded to GND.

In the present invention, two silicon magneto-sensitive triodes (SMST1 and SMST2) and two connected collector load resistors (R _L1 and R _L2 ) constitute a first differential test circuit for detecting the magnetic field in the x-axis direction .

According to a preferred embodiment of the present invention, one end of the third collector C3 of the _third silicon magneto-sensitive triode _SMST3 is connected to the third collector load resistor RL3, and the first output voltage of the y-axis is formed at the connection. _V3 ,

One end of the fourth collector _C4 of the fourth silicon magneto-sensitive triode _SMST4 is connected to the fourth collector load resistor RL4, and the y-axis second output voltage _V4 is formed at the connection.

In a further preferred embodiment, the third base electrode B ₃ , the fourth base electrode B ₄ , the other end of the third collector load resistor _RL3 and the other end of the fourth collector load resistor _RL4 are commonly connected to a power supply _VDD .

Wherein, the emitter of the third silicon magneto-sensitive triode SMST3 and the emitter of the fourth silicon magneto-sensitive triode SMST4 are commonly connected to the ground GND.

In the present invention, two silicon magneto-sensitive triodes (SMST3 and SMST4) and two collector load resistors (R _L3 and R _L4 ) connected respectively constitute a second differential test circuit, which is used to detect the magnetic field in the y-axis direction .

According to a preferred embodiment of the present invention, the Hall magnetic field sensor H includes a magnetic sensitive layer, two control current poles and two Hall output terminals, wherein,

The two control current poles are the first control current pole I _H1 and the second control current pole I _H2 , and the two Hall output terminals are the first Hall output terminal V _H1 and the second Hall output terminal V _H2 .

In a further preferred embodiment, as shown in FIG. 3 , the space between the first control current electrode I _H1 and the first Hall output terminal V _H1 is equivalent to a first equivalent resistance R _H1 , and the first control current electrode is equivalent to a first equivalent resistance R H1 . The distance between I _H1 and the second Hall output terminal V _H2 is equivalent to a second equivalent resistance R _H2 , and the distance between the second control current pole I _H2 and the first Hall output terminal V _H1 is equivalent to a third equivalent resistance R _H3 , between the second control current electrode I _H2 and the second Hall output terminal V _H2 is equivalent to a fourth equivalent resistance R _H4 .

In a further preferred embodiment, as shown in FIG. 3 , the first equivalent resistance R _H1 and the third equivalent resistance R _H3 are connected, and the first z-axis output voltage V _z1 is formed at the connection, and the second equivalent resistance R H1 is connected. The equivalent resistor R _H2 is connected to the fourth equivalent resistor R _H4 , and the second output voltage V _z2 of the z-axis is formed at the connection.

In the present invention, four equivalent resistors R _H1 , R _H2 , R _H3 and R _H4 form a Wheatstone bridge structure for detecting the magnetic field in the z-axis direction.

According to a preferred embodiment of the present invention, the magnetic sensitive layer of the Hall magnetic field sensor is a phosphorus-doped nano-silicon film nc-Si:H(n ⁺ ), and the doping amount of phosphorus is 5E13 ^-3 - 1E15cm ^-3 .

In the present invention, the phosphorus-doped nano-silicon film is fabricated on the upper surface of the device layer 1 by in-situ doping, which can significantly improve the magnetic sensitivity characteristics of the Hall magnetic field sensor in the three-dimensional magnetic field sensor, and can ensure the x-axis The consistency of detection in three directions of , y-axis and z-axis.

Among them, combined with the main factors affecting the characteristics of the Hall magnetic field sensor, when too much phosphorus is doped, the magnetic sensitivity will be reduced, and when too little phosphorus is doped, the output impedance will be too large.

In a further preferred embodiment, the thickness of the magnetic sensitive layer of the Hall magnetic field sensor in the magnetic field sensor is 50 nm˜120 nm.

Due to the multi-directionality of the three-dimensional magnetic field in space, two or more magnetic sensitive components need to be used in combination. The consistency of detection in three directions of the z-axis.

According to a preferred embodiment of the present invention, an isolation groove 5 is formed on the device layer 1 around each silicon magneto-sensitive triode to prevent the mutual influence between the silicon magneto-sensitive triode and other devices.

In a further preferred embodiment, the isolation trench 5 is n ⁺ type doped.

The inventors of the present invention have found out through research that an n ⁺ type doped isolation trench is fabricated on the device layer (<100> crystal orientation high-resistance p-type single crystal silicon), so that the inside and outside of the isolation trench are P-type, and the distance between the isolation trench and the device layer is The inner and outer contact surfaces form a PN junction. Since the PN junction has unidirectional conductivity, there will always be a contact surface (inner contact surface or outer contact surface) that is not conductive. Isolation prevents conduction between devices, avoids mutual interference, and improves the stability of the sensor.

According to a preferred embodiment of the present invention, as shown in FIG. 1 , a suspended structure is etched at the middle position of the acceleration sensor, and the suspended structure includes a mass block at the center position and a mass block located on both sides of the mass block. Four double L-beams;

Wherein, there are two mass blocks, which are a first mass block m ₁ and a second mass block m ₂ ;

Each of the double L-shaped beams includes two single L-shaped beams, and the four double L-shaped beams have a total of eight single L-shaped beams, which are the first single L-shaped beam L ₁ and the second single L-shaped beam L ₂ . , the third single L-shaped beam L ₃ , the fourth single L-shaped beam L ₄ , the fifth single L-shaped beam L ₅ , the sixth single L-shaped beam L ₆ , the seventh single L-shaped beam L ₇ and the eighth single L-shaped beam L 6 Profile beam L ₈ .

Preferably, the first single L-shaped beam L ₁ , the second single L-shaped beam L ₂ , the fifth single L-shaped beam L ₅ and the seventh single L-shaped beam L ₇ are arranged on the center line of the x-axis or y-axis direction one side of , and both are parallel to the center line in the x-axis or y-axis direction;

The third single L-shaped beam L ₃ , the fourth single L-shaped beam L ₄ , the sixth single L-shaped beam L ₆ and the eighth single L-shaped beam L ₈ are arranged on the other side of the center line in the x-axis or y-axis direction. side, and both are parallel to the center line in the x-axis or y-axis direction.

In the present invention, each double L-shaped beam is set as two single L-shaped beams connected to form eight single L-shaped beam structures, which can obviously improve the sensitivity in the x-axis direction and the y-axis direction, so that the x-axis direction, The sensitivity in the y-axis direction is close to the sensitivity in the z-axis direction, which promotes the convergence of the sensitivity characteristics in all directions.

In a further preferred embodiment, a first intermediate beam L ₉ and a second intermediate beam L ₁₀ are further arranged between the first mass m ₁ and the second mass m ₂ ;

Preferably, the first mass m ₁ and the second mass m ₂ are symmetrically arranged along the x-axis direction or the y-axis direction at the center of the acceleration sensor,

The first intermediate beam _L9 and the second intermediate beam _L10 are symmetrically arranged along the x-axis direction or the y-axis direction at the center of the acceleration sensor,

The first intermediate beam L ₉ and the second intermediate beam L ₁₀ are both perpendicular to the first mass m ₁ and the second mass m ₂ .

In a further preferred embodiment, the thicknesses of the first mass m ₁ and the second mass m ₂ are both equal to the maximum thickness of the magnetic field/acceleration integrated sensor;

The thicknesses of the first single L-shaped beam L ₁ to the eighth single L-shaped beam L ₈ , the first intermediate beam L ₉ and the second intermediate beam L ₁₀ are all the same as the thickness of the device layer 1 .

In the present invention, the thicknesses of the mass block and the sensor are the distances between the upper and lower surfaces along the z-axis direction.

According to a preferred embodiment of the present invention, on the side of the first mass m ₁ opposite to the first intermediate beam and the second intermediate beam, a second single L-shaped beam L ₂ is connected, and a fourth single L-shaped beam L 2 is connected. L-shaped beam L ₄ , the seventh single L-shaped beam L ₇ and the eighth single L-shaped beam L ₈ ;

A first single L-shaped beam L ₁ , a third single L-shaped beam L ₃ , and a fifth single L-shaped beam are connected to the side of the second mass m ₂ opposite to the first intermediate beam and the second intermediate beam Beam L ₅ and sixth single L-beam L ₆ .

The L-shaped beam, the middle beam and the mass block together form the structure of the three-axis acceleration sensor.

In a further preferred embodiment, the roots of the first single L-shaped beam L ₁ , the second single L-shaped beam L ₂ , the third single L-shaped beam L ₃ and the fourth single L-shaped beam L ₄ are respectively provided There are a first varistor R _x1 in the x-axis direction, a second varistor R _x2 in the x-axis direction, a third varistor R _x3 in the x-axis direction, and a fourth varistor R _x4 in the x-axis direction;

Wherein, the first varistor R _x1 in the x-axis direction, the second varistor R _x2 in the x-axis direction, the third varistor R _x3 in the x-axis direction, and the fourth varistor R _x4 in the x-axis direction are arranged parallel to each other .

In a further preferred embodiment, as shown in FIG. 1 and FIG. 4 , one end of the first varistor R _x1 in the x-axis direction is connected to one end of the second varistor R _x2 in the x-axis direction, and the connection is formed The x-axis first output voltage _Vxout1 ; one end of the third varistor Rx3 in the _x -axis direction is connected to one end of the fourth varistor Rx4 in the _x -axis direction, and the connection forms the x-axis second output voltage _Vxout2 ;

Preferably, the other end of the first varistor Rx1 in the _x -axis direction and the other end of the fourth varistor _Rx4 in the x-axis direction are commonly connected to the power supply V _DD , and the second varistor Rx2 in the _x -axis direction is connected to the power supply V DD . The other end of , and the other end of the third varistor R _x3 in the x-axis direction are commonly grounded (GND).

Among them, the _four varistors ( _{R x1} , R _x2 , R x ₁ , R _{x 2} , R _x3 , R _x4 ) form the first Wheatstone bridge for detecting the acceleration in the x-axis direction. Under the action of acceleration along the x-axis direction, the output terminals V _xout1 and V _xout2 of the Wheatstone bridge change, which can realize the detection of the x-axis acceleration.

According to a preferred embodiment of the present invention, in the fifth single L-shaped beam L ₅ , the sixth single L-shaped beam L ₆ , the seventh single L-shaped beam L ₇ and the eighth single L-shaped beam L ₈ The root is respectively provided with a first varistor R _y1 in the y-axis direction, a second varistor R _y2 in the y-axis direction, a third varistor R _y3 in the y-axis direction, and a fourth varistor R _y4 in the y-axis direction,

Wherein, the first varistor R _y1 in the y-axis direction, the second varistor R _y2 in the y-axis direction, the third varistor R _y3 in the y-axis direction, and the fourth varistor R _y4 in the y-axis direction are arranged in parallel with each other .

In a further preferred embodiment, one end of the first varistor R _y1 in the y-axis direction is connected to one end of the second varistor R _y2 in the y-axis direction, and the connection forms the y-axis first output voltage V _yout1 ; y One end of the third varistor R _y3 in the axial direction is connected to one end of the fourth varistor R _y4 in the y-axis direction, and the connection forms the second y-axis output voltage V _yout2 .

In a further preferred embodiment, the other end of the first varistor R _y1 in the y-axis direction and the other end of the fourth varistor R _y4 in the y-axis direction are jointly connected to the power supply V _DD , and the second varistor in the y-axis direction is connected to the power supply V DD . The other end of R _y2 and the other end of the third varistor R _y3 in the y-axis direction are commonly grounded.

Among them, the fifth single L-shaped beam L ₅ , the sixth single L-shaped beam L ₆ , the seventh single L-shaped beam L ₇ and the eighth single L-shaped beam L ₈ are four varistors (R _y1 , R _y2 , R _y3 , R _y4 ) form the second Wheatstone bridge for detecting the acceleration in the y-axis direction. Under the action of acceleration along the y-axis direction, the output terminals V _yout1 and V _yout2 of the Wheatstone bridge change, which can realize the detection of the y-axis acceleration.

According to a preferred embodiment of the present invention, at the root of the connection between the first intermediate beam _L9 and the first mass m ₁ and the second mass m ₂ , first varistors in the z-axis direction are respectively provided R _z1 and the second varistor R _z2 in the z-axis direction;

_A third varistor R _z3 in the z-axis direction and a fourth varistor in the z-axis direction are respectively arranged at the root of the second intermediate beam L10 where the first mass block m ₁ and the second mass block m ₂ are connected. R _z4 ;

Wherein, the first varistor R _z1 in the z-axis direction and the second varistor R _z2 in the z-axis direction are arranged perpendicular to each other,

The third varistor R _z3 in the z-axis direction and the fourth varistor R _z4 in the z-axis direction are arranged perpendicular to each other.

In a further preferred embodiment, one end of the first varistor R _z1 in the z-axis direction is connected to one end of the second varistor R _z2 in the z-axis direction, and the connection forms the first z-axis output voltage V _zout1 ; z One end of the third varistor R _z3 in the axial direction is connected to one end of the fourth varistor R _z4 in the z-axis direction, and the connection forms the second z-axis output voltage V _zout2 .

In a further preferred embodiment, the other end of the first varistor R _z1 in the z-axis direction and the other end of the fourth varistor R _z4 in the z-axis direction are jointly connected to the power supply V _DD , and the second voltage in the z-axis direction is connected to the power supply V DD . The other end of the varistor R _z2 and the other end of the third varistor R _z3 in the z-axis direction are commonly grounded.

Among them, the four z-axis direction varistors (R _z1 , R _z2 , R _z3 , R _z4 ) at the root of the first intermediate beam and the second intermediate beam form a third Wheatstone bridge for detecting the z-axis direction acceleration. Under the action of acceleration along the z-axis, the output terminals V _zout1 and V _zout2 of the Wheatstone bridge change, which can realize the detection of the z-axis acceleration.

Among them, ΔR in Figure 4 represents the relative change of the resistance value of the chip when the chip is affected by an external acceleration or a magnetic field.

According to a preferred embodiment of the present invention, the varistors in the x-axis, y-axis and z-axis directions are all boron-doped nano-polysilicon thin film resistors, preferably p-type boron-doped nano-polysilicon thin film resistors.

In the present invention, when the magnetic field sensor and the acceleration sensor are integrated and fabricated, the SOI wafer of p-type <100> crystal orientation high-resistance single-crystal silicon is used as the substrate, which will have a certain impact on the sensitivity of the piezoresistive acceleration sensor. , In order to solve the compatibility problem, the p-type boron-doped nano-polysilicon thin film resistor is preferably used as the sensitive element of the acceleration sensor in the present invention, so as to ensure the sensitivity of the acceleration sensor.

The inventors have found that the boron-doped nano-polysilicon film has more superior piezoresistive properties than other conventional polysilicon films, has a small temperature coefficient of strain factor, and a small temperature coefficient of resistance, and can realize pressure-sensitive testing with high sensitivity and wide operating temperature range. Therefore, it can be ensured that the acceleration sensor has high sensitivity on the p-type substrate, and the single-chip integrated sensor can simultaneously measure the three-dimensional magnetic field and the three-axis acceleration.

In a further preferred embodiment, the doping amount of boron ranges from 1E13 ^-3 to 1E15 cm ^-3 .

The inventors found that when the doping amount of boron is too high, heavy doping is formed, resulting in a low resistivity of the varistor. When the external acceleration acts, the piezoresistive coefficient decreases, and the output voltage of the Wheatstone bridge is low. Affect the varistor characteristics; when the doping amount of boron is too low, light doping is formed, resulting in a high resistivity of the varistor. When the external acceleration acts, the resistance change is not obvious, and the output voltage of the Wheatstone bridge is relatively high. low, affecting the pressure-sensitive characteristics.

In a further preferred embodiment, the thickness of the nano-polysilicon thin film is 60-100 nm.

According to a preferred embodiment of the present invention, a glass sheet is further provided below the acceleration sensor, which has a groove structure and is bonded and connected with the support silicon 2, so that the two mass blocks of the acceleration sensor can be placed in the groove. move freely inside.

In a further preferred embodiment, the glass sheet is a borosilicate glass sheet with a thickness of 0.5-1 mm.

In the present invention, the glass sheet has an overload protection function, which avoids the complicated process of thinning the mass block, so that the mass block at the center of the acceleration sensor can move freely in the groove of the glass sheet.

The present invention also provides an integrated process method for a magnetic field/acceleration integrated sensor, which is preferably used for preparing the above-mentioned magnetic field/acceleration integrated sensor, as shown in Figures 5-a to 5-e, the method includes the following steps:

Step 1, cleaning the SOI sheet (as shown in FIG. 5-a ), the 0th photolithography (as a registration mark in the lithography process), and making a registration mark on the device layer 1 .

Among them, the RCA standard cleaning method is used to clean the single crystal silicon substrate, and the cleaning is carried out as follows: the SOI sheet is boiled with concentrated sulfuric acid until white smoke is emitted, and after cooling, it is rinsed with a large amount of 15% deionized water, and then an electronic cleaning solution is used respectively. No. 1 APM (SC-1), electronic cleaning liquid No. 2 HPM (SC-2), the main components and volume ratio of No. 1 liquid are: ammonia water: hydrogen peroxide: water = 1:1:5 (the concentration of ammonia water is 27%, the concentration of hydrogen peroxide is 30%), and the main components and volume ratio of No. 2 solution are: hydrochloric acid: hydrogen peroxide: water = 1:1:5 (the concentration of hydrochloric acid is 37%, and the concentration of hydrogen peroxide is 30%) , washed twice each, then rinsed with plenty of deionized water, and finally put in a spin dryer to dry.

According to a preferred embodiment of the present invention, the SOI sheet includes a device layer 1 and a supporting silicon 2;

The device layer 1 is p-type <100> crystal orientation high-resistance single crystal silicon, and the thickness of the device layer 1 is 20-50 μm, preferably 25-35 μm.

In a further preferred embodiment, the resistivity of the device layer 1 is greater than 100 Ω·cm.

In a further preferred embodiment, the supporting silicon 2 is p-type <100> crystal orientation high-resistance single crystal silicon, and its thickness is 420-550 μm, preferably 450-525 μm, and more preferably 475-500 μm.

Preferably, a first silicon dioxide layer 3 is disposed between the device layer 1 and the supporting silicon 2 , and the thickness of the first silicon dioxide layer 3 is 500 nm˜800 nm.

Step 2, the first oxidation, growing thin oxygen on the device layer 1 as an ion implantation buffer layer.

Wherein, the thin oxygen is silicon dioxide, and its thickness is 30-50 nm.

Step 3, the first photolithography, the isolation trench window is etched on the upper surface of the device layer 1, then phosphorus ion implantation is performed, n ⁺ type doping is performed, and the isolation trench is formed by processing at 600-1200° C. for 8-10 hours. (as shown in Figure 5-b).

According to a preferred embodiment of the present invention, the doping concentration of the n ⁺ type doping is 5E14 ^-3 -1E15 cm ^-3 .

The inventors have found that the PN junction isolation is facilitated with the above-mentioned doping concentration.

Among them, the advantages of using the above annealing temperature and vacuum treatment time are that high temperature annealing can activate impurity ions and eliminate the damage of ion implantation, and vacuum treatment can prevent other substances such as oxygen in the atmosphere from affecting the chip. If the annealing temperature is too high or the treatment time is too long, the implanted ions may be displaced, which may easily lead to the displacement of the implanted ions. Error and defect density.

Step 4, the second photolithography, the load resistance window is etched on the upper surface of the device layer 1, phosphorus ions are implanted, and n ^- type doping is performed to form the load resistance.

Step 5, the third photolithography, the base region window is etched on the upper surface of the device layer 1, boron ions are implanted, and p ⁺ type heavy doping is performed to form the base region.

Among them, the concentration of p ⁺ type heavy doping is 1E13 ^-3 -1E15cm ^-3 .

Step 6, high temperature annealing to form impurity distribution.

According to a preferred embodiment of the present invention, the high-temperature annealing treatment is performed as follows: treatment in a vacuum environment at 600-1200° C. for 20-30 minutes.

Among them, the advantages of using the above annealing temperature and vacuum treatment time are: high temperature annealing can activate impurity ions, and vacuum treatment can prevent other substances such as oxygen in the atmosphere from affecting the chip. If the annealing temperature is too low or the treatment time is too short, the damage of the ion implantation cannot be eliminated well, the ions cannot reach the replacement position, and the surface crystalline state is not good; if the annealing temperature is too high or the treatment time is too long, the implanted ions may displacement, which can easily lead to dislocation and defect density.

In step 7, the SOI sheet is cleaned, and a silicon dioxide layer is grown on the surface of the device layer 1 by chemical vapor deposition.

The thickness of the grown silicon dioxide layer is 500 to 600 nm.

Step 8, the fourth photolithography, using chemical vapor deposition method to grow phosphorus-doped nc-Si:H(n ⁺ ) in situ to form a phosphorus-doped nc-Si:H(n ⁺ ) film as the magnetic sensitive layer of the Hall magnetic field sensor (as shown in Figure 5-b).

According to a preferred embodiment of the present invention, the thickness of the in-situ grown nc-Si:H(n ⁺ ) thin film is 50-120 nm.

In a further preferred embodiment, the doping amount of the phosphorus ranges from 5E13 ^-3 to 1E15cm ^-3 .

In step 9, the SOI sheet is cleaned, and a boron-doped nano-polysilicon thin film is grown in-situ on the upper surface of the device layer 1 by plasma chemical vapor deposition (PECVD).

According to a preferred embodiment of the present invention, the deposition temperature is 600°C to 650°C, preferably 620°C.

In a further preferred embodiment, the thickness of the in-situ boron-doped nano-polysilicon thin film is 60-100 nm.

In a further preferred embodiment, the doping amount of the boron ranges from 1E13 ^-3 to 1E15 cm ^-3 .

Step 10, the fifth photolithography, etching the boron-doped nano-polysilicon film on the upper surface of the device layer 1 to form 12 varistors (R _x1 , R _x2 , R _x3 , R _x4 , R _y1 , R _y2 , R _y3 , R _y4 , R _z1 , R _z2 , R _z3 , R _z4 ) (as shown in Figure 5-c).

Step 11 , cleaning the silicon wafer, and using a chemical vapor deposition method to grow a silicon dioxide layer on the upper surface of the device layer 1 as an insulating layer.

The thickness of the grown silicon dioxide layer is 400 to 600 nm.

Step 12, the sixth photolithography, etching lead holes on the upper surface of the device layer 1.

Step 13, the seventh photolithography, the C-type silicon cup emission area window and the mass block of the acceleration sensor chip are etched on the back of the support silicon 2 by using a deep groove etching technique (ICP).

Wherein, deep groove etching technology (ICP) is used to etch to the first silicon dioxide layer 3 .

Step 14, performing n ⁺ type heavy doping at the emitter region window on the back of the support silicon 2 to form an emitter region, and then performing high temperature annealing treatment.

Wherein, the high-temperature annealing is treated as follows: treatment in a vacuum environment at 600-1200° C. for 20-30 minutes.

Step 15: Clean the silicon wafer, grow a metal aluminum layer on the upper surface of the device layer 1 and the lower surface of the supporting silicon 2 by magnetron sputtering to form a metal electrode layer; The aluminum layer, forming the metal electrode.

Wherein, the thickness of the metal aluminum layer is 0.5-1.0 μm.

Step 16 , cleaning the silicon wafer, and using a chemical vapor deposition method to grow a silicon dioxide layer on the upper surface of the device layer 1 as a passivation layer.

Wherein, the thickness of the grown silicon dioxide layer is 500-600 nm.

Step 17, the ninth photolithography, the passivation layer is etched to form the bonding point; then the silicon wafer is cleaned and alloyed to form an ohmic contact (as shown in Fig. 5-d).

According to a preferred embodiment of the present invention, the alloying treatment is carried out as follows: treatment at 300-500°C for 10-50min, preferably at 400-450°C for 20-40min, more preferably at 420°C for 30min .

Step 18, the tenth photolithography, deep groove etching (ICP) etching the silicon wafer device layer 1, etching to the first silicon dioxide layer 3, releasing the L-shaped beam structure (as shown in Figure 5-e ) ).

Step 19, bonding the SOI sheet with the borosilicate glass sheet with the overload protection structure.

Wherein, the borosilicate glass sheet has a groove structure and is bonded and connected with the support silicon 2, so that the two mass blocks of the acceleration sensor can move freely in the groove.

Preferably, its thickness is 0.5-1 mm.

In the present invention, the monolithic integrated three-dimensional magnetic field/three-axis acceleration sensor chip is fabricated on the SOI wafer device layer (p-type <100> crystal orientation high-resistance monocrystalline silicon) based on micro-electromechanical processing technology (MEMS). And through the bonding process and the inner lead pressure welding technology to realize the chip packaging, it can realize the simultaneous measurement of the three-dimensional magnetic field and the three-axis acceleration. The prepared magnetic field/acceleration integrated sensor has the characteristics of small size and easy mass production.

Example

Example 1

Follow the steps below to integrate the magnetic field/acceleration integrated sensor:

Step 1, cleaning the SOI sheet, the 0th photolithography (as the registration mark of the photolithography process), and making the registration mark on the device layer.

Among them, the RCA standard cleaning method is used to clean the single crystal silicon substrate, and the cleaning is carried out as follows: the SOI sheet is boiled with concentrated sulfuric acid until white smoke is emitted, and after cooling, it is rinsed with a large amount of 15% deionized water, and then an electronic cleaning solution is used respectively. No. 1 APM (SC-1), electronic cleaning liquid No. 2 HPM (SC-2), the main components and volume ratio of No. 1 liquid are: ammonia water: hydrogen peroxide: water = 1:1:5 (the concentration of ammonia water is 27%, the concentration of hydrogen peroxide is 30%), and the main components and volume ratio of No. 2 solution are: hydrochloric acid: hydrogen peroxide: water = 1:1:5 (the concentration of hydrochloric acid is 37%, and the concentration of hydrogen peroxide is 30%) , washed twice each, then rinsed with plenty of deionized water, and finally put in a spin dryer to dry.

Among them, the device layer is p-type <100> crystal orientation high-resistance single-crystal silicon with a thickness of 30 μm and a resistivity greater than 100 Ω·cm, and the supporting silicon is p-type <100> crystal-oriented high-resistance single crystal silicon with a thickness of 490 μm. The thickness of the first silicon dioxide layer 3 is 600 nm.

Step 2, the first oxidation, growing thin oxygen (silicon dioxide) on the device layer as an ion implantation buffer layer.

Wherein, the thickness of the thin oxygen is 40 nm.

Step 3, the first photolithography, phosphorus ion implantation is performed on the upper surface of the device layer to realize n ⁺ type doping, and the isolation trench is formed by processing at 1000° C. for 10 hours;

Among them, the doping concentration of n ⁺ type doping is 5E14 ^-3 cm ^-3 .

Step 4, the second photolithography, the load resistance window is etched on the upper surface of the device layer, phosphorus ions are implanted, and n ^- type doping is performed to form the load resistance.

Step 5, the third photolithography, the base region window is etched on the upper surface of the device layer 1, boron ions are implanted, and p ⁺ type heavy doping is performed to form the base region.

Among them, the concentration of p ⁺ type heavy doping is 1E13 ^-3 cm ^-3 .

Step 6, high temperature annealing to form impurity distribution.

Among them, the high-temperature annealing treatment was carried out as follows: 1000 °C for 25 min in a vacuum environment.

Step 7, cleaning the SOI sheet, and using a chemical vapor deposition method to grow a silicon dioxide layer on the upper surface of the device layer.

The thickness of the grown silicon dioxide layer was 550 nm.

Step 8, the fourth photolithography, using chemical vapor deposition method to grow phosphorus-doped nc-Si:H(n ⁺ ) in situ to form a phosphorus-doped nc-Si:H(n ⁺ ) film as the magnetic sensitive layer of the Hall magnetic field sensor .

Wherein, the thickness of the in-situ nc-Si:H(n ⁺ ) thin film is 90 nm; the doping amount of phosphorus is 5E13 ^{- 3} cm ^-3 .

In step 9, the SOI sheet is cleaned, and a boron-doped nano-polysilicon thin film is grown in-situ on the upper surface of the device layer by plasma chemical vapor deposition (PECVD).

Among them, the deposition temperature was 620°C, the thickness of the in-situ boron-doped nano-polysilicon film was 80 nm, and the doping amount of boron was 1E13 ^-3 cm ^-3

Step 10, the fifth photolithography, etching the boron-doped nano-polysilicon film on the upper surface of the device layer to form 12 varistors ( _Rx1 , _Rx2 , _Rx3 , _Rx4 , _Ry1 , _Ry2 , R _y3 , R _y4 , R _z1 , R _z2 , R _z3 , R _z4 ).

In step 11, the silicon wafer is cleaned, and a silicon dioxide layer is grown on the upper surface of the device layer by chemical vapor deposition as an insulating layer.

The thickness of the grown silicon dioxide layer was 40 nm.

Step 12, the sixth photolithography, etching lead holes on the upper surface of the device layer.

Step 13, the seventh photolithography, the C-type silicon cup emission area window is etched on the back of the support silicon 2 by using a deep groove etching technique (ICP).

Wherein, deep groove etching technology (ICP) is used to etch to the first silicon dioxide layer.

Step 14, performing n ⁺ type heavy doping at the emitter region window on the back of the support silicon 2 to form an emitter region, and then performing high temperature annealing treatment.

Among them, the doping concentration of n ⁺ type doping is 5E13 ^-3 cm ^-3 .

Among them, the high-temperature annealing treatment is as follows: treatment in a vacuum environment at 850 °C for 28 min.

Step 15, clean the silicon wafer, grow a metal aluminum layer on the upper surface of the device layer and the lower surface of the supporting silicon 2 by magnetron sputtering to form a metal electrode layer; then perform the eighth photolithography, and reversely etch the metal aluminum layer on the upper surface of the device layer , forming a metal electrode.

The thickness of the metal aluminum layer is 0.8 μm.

In step 16, the silicon wafer is cleaned, and a silicon dioxide layer is grown on the upper surface of the device layer by chemical vapor deposition as a passivation layer.

The thickness of the grown silicon dioxide layer was 550 nm.

Step 17, the ninth photolithography, the passivation layer is etched to form the bonding point; then the silicon wafer is cleaned and alloyed to form an ohmic contact.

Among them, the alloying treatment was carried out as follows: treatment at 420° C. for 30 min.

Step 18, the tenth photolithography, deep groove etching (ICP) etching the silicon wafer device layer, etching to the first silicon dioxide layer, releasing the L-shaped beam structure.

Step 19, bonding the SOI sheet with the borosilicate glass sheet with the overload protection structure.

Wherein, the borosilicate glass sheet has a groove structure with a thickness of 0.5-1 mm, and is bonded and connected with the supporting silicon.

Example 2

The method used in this embodiment is similar to that in Embodiment 1, except that, in Step 1, the thickness of the device layer is 50 μm, and the thickness of the supporting silicon is 420 μm.

Example 3

The method used in this example is similar to that in Example 1, with the difference that, in step 3, the high-temperature annealing treatment is carried out as follows: treatment in a vacuum environment at 1200° C. for 8 hours.

Example 4

The method used in this example is similar to that in Example 1, except that in step 6, the high-temperature annealing treatment is performed as follows: treatment in a vacuum environment at 600° C. for 30 minutes.

Example 5

The method used in this embodiment is similar to that in Embodiment 1, except that in step 8, the thickness of the in-situ grown nc-Si:H(n ⁺ ) thin film is 50 nm.

Example 6

The method used in this embodiment is similar to that in Embodiment 1, except that, in step 8, the thickness of the in-situ grown nc-Si:H(n ⁺ ) thin film is 120 nm.

Example 7

The method used in this embodiment is similar to that in embodiment 1, except that in step 8, the doping amount of phosphorus is 1E15cm ⁻³ .

Example 8

The method used in this embodiment is similar to that of embodiment 1, the difference is that in step 9, the deposition temperature is 650°C.

Example 9

The method used in this embodiment is similar to that in Embodiment 1, except that in step 9, the thickness of the boron-doped nano-polysilicon thin film grown in situ is 60 nm.

Example 10

The method used in this embodiment is similar to that in Embodiment 1, except that in step 9, the thickness of the boron-doped nano-polysilicon thin film grown in situ is 100 nm.

Example 11

The method used in this embodiment is similar to that in embodiment 1, the difference is that in step 9, the doping amount of boron is 1E15cm ⁻³ .

Example 12

The method used in this example is similar to that in Example 1, except that, in step 17, the alloying treatment is performed as follows: treatment at 400° C. for 40 min.

Example 13

The method used in this example is similar to that in Example 1, with the difference that, in step 17, the alloying treatment is performed as follows: treatment at 450° C. for 20 minutes.

Experimental example

Experimental example 1

A magnetic field generator (CH-100), programmable linear DC power supply (RIGOL DP832A) and digital multimeter (Agilent 34410A) are used to build a three-dimensional magnetic field sensor characteristic test system. At room temperature, the operating voltage is 5V, and the base injects current. ( _Ib ) under the situation of 1mA, 2mA, 3mA, 4mA and 5mA respectively, the characteristic test is carried out to the magnetic field sensor described in Embodiment 1 of the present utility model, and the magnetic field sensor is respectively applied along the x-axis, y-axis and z-axis direction. Magnetic field (-500mT～500mT, step size is 100mT), respectively collect the output voltage of the first differential structure, the second differential structure and the Hall element of the magnetic field sensor. The relationship between the output voltage of the magnetic field sensor and the applied magnetic field is shown in Figure 6-a ~ shown in Figure 6-c.

Among them, Figure 6-a is the relationship curve of the output voltage of the first differential structure of the magnetic field sensor with the applied magnetic field when the magnetic field is along the x-axis direction; Figure 6-b is the output voltage of the second differential structure of the magnetic field sensor when the magnetic field is along the y-axis direction The relationship curve with the change of the applied magnetic field; Figure 6-c is the relationship curve of the output voltage of the Hall element of the magnetic field sensor when the magnetic field is along the z-axis direction with the change of the applied magnetic field.

It can be seen from Figure 6-a and Figure 6-b that when the external magnetic field is constant, the output voltage of the first differential structure and the second differential structure of the magnetic field sensor along the x-axis and y-axis directions increases with the increase of the base injection current; when When the base injection current is constant, the output voltages of the first differential structure and the second differential structure along the x-axis and y-axis of the magnetic field sensor increase with the increase of the applied magnetic field; it can be seen from Figure 6-c that when the input voltage is constant at 5V , the output voltage of the Hall element that detects the magnetic field in the z-axis direction increases with the increase of the applied magnetic field.

A standard vibration table (Dongling ESS-050), programmable linear DC power supply (RIGOL DP832A) and digital multimeter (Agilent 34410A) were used to build a three-axis accelerometer characteristic test system. Apply acceleration along the x-axis, y-axis and z-axis to the acceleration chip described in Example 1 (0-30g, step size is 5g), and collect the first Wheatstone bridge and the second Wheatstone bridge of the acceleration chip respectively. The relationship between the output voltage of the power-on bridge and the third Wheatstone bridge, the output voltage of the acceleration sensor and the applied acceleration is shown in Figure 7.

Among them, curve A is the relationship curve of the output voltage of the first Wheatstone bridge with the applied acceleration when the applied acceleration is along the x-axis direction, and curve B is when the applied acceleration is along the y-axis direction, the second Wheatstone bridge The relationship curve of the output voltage of the bridge with the applied acceleration, the curve C is the relationship curve of the output voltage of the third Wheatstone bridge with the applied acceleration when the applied acceleration is along the z-axis direction.

It can be seen from Figure 7 that when the working voltage is constant, the output voltages of the first Wheatstone bridge, the second Wheatstone bridge and the third Wheatstone bridge of the acceleration sensor increase linearly with the increase of the applied acceleration.

It can be seen from the above that when the power supply voltage is 5.0V and the base injection current is 5mA, the sensitivity of the magnetic field sensor in the x-axis direction of the sensor of the present invention is 154mV/T, the sensitivity of the magnetic field sensor in the y-axis direction is 158mV/T, and the magnetic field in the z-axis direction is 158mV/T. The sensitivity of the sensor is 91mV/T; the sensitivity of the acceleration sensor in the x-axis direction is 0.95mV/g, the sensitivity of the acceleration sensor in the y-axis direction is 0.61mV/g, and the sensitivity of the acceleration sensor in the z-axis direction is 0.14mV/g. Therefore, the integrated sensor of the present invention can realize the simultaneous detection of the three-dimensional magnetic field and the three-axis acceleration, and the obtained sensitivities in the three directions of x, y and z are close to the same.

In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inside", "outside", "front", "rear", etc. is based on the work of the present utility model. The orientation or positional relationship in the state is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a Utility Model Restrictions. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or an integral connection is common; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

The present invention has been described above with reference to the preferred embodiments, but these embodiments are only exemplary and only serve an illustrative role. On this basis, various replacements and improvements can be made to the present invention, which all fall within the protection scope of the present invention.

Claims (10)

1. The magnetic field/acceleration integrated sensor is characterized by comprising a magnetic field sensor and an acceleration sensor which are arranged on the same chip so as to realize the simultaneous measurement of a three-dimensional magnetic field and three-axis acceleration;

the magnetic field/acceleration integrated sensor takes an SOI (silicon on insulator) sheet as a substrate, wherein the SOI sheet comprises a device layer (1), a supporting silicon (2) and a first silicon dioxide layer (3);

wherein the thickness of the device layer (1) is 20-50 μm, and the thickness of the supporting silicon (2) is 420-550 μm;

the magnetic field sensor comprises four silicon magnetosensitive triodes which are arranged on the device layer (1) and have a three-dimensional structure and a Hall magnetic field sensor (H),

the four silicon magnetosensitive triodes are combined in pairs to form two magnetosensitive units which are respectively used for detecting magnetic fields in the x-axis direction and the y-axis direction;

the Hall magnetic field sensor (H) is used for detecting a magnetic field in the z-axis direction;

a suspension structure is etched in the middle of the acceleration sensor, and the suspension structure comprises a mass block located in the center and four double-L-shaped beams located on two sides of the mass block;

the mass blocks are two, respectively first mass blocks (m)₁) And a second mass (m)₂)；

Each double-L-shaped beam comprises two single-L-shaped beams, and the four double-L-shaped beams comprise eight single-L-shaped beams which are respectively a first single-L-shaped beam (L)₁) Second single L-shaped beam (L)₂) Third single L-shaped beam (L)₃) Fourth single L-shaped beam (L)₄) Fifth single L-shaped Beam (L)₅) Sixth single L-shaped beam (L)₆) Seventh single L-shaped beam (L)₇) And eighth single L-shaped beam (L)₈)。

2. The sensor of claim 1, wherein the four silicon magnetosensitive transistors are a first silicon magnetosensitive transistor (SMST1), a second silicon magnetosensitive transistor (SMST2), a third silicon magnetosensitive transistor (SMST3), and a fourth silicon magnetosensitive transistor (SMST4), respectively,

wherein the first silicon magnetic sensitive triode (SMST1) and the second silicon magnetic sensitive triode (SMST2) are symmetrically arranged along the x axis of the magnetic field sensor at two sides of the center of the magnetic field sensor chip,

and the third silicon magnetosensitive triode (SMST3) and the fourth silicon magnetosensitive triode (SMST4) are symmetrically arranged at two sides of the center of the magnetic field sensor chip along the y axis of the magnetic field sensor.

3. The sensor of claim 1, wherein the magnetic sensitive layer of the Hall magnetic field sensor is a phosphorus-doped nano-silicon thin film nc-Si: H (n)⁺)，

The thickness of the magnetic sensitive layer is 50 nm-120 nm.

4. A sensor according to claim 1, characterized in that an isolation trench (5) is made on the device layer (1) around each silicon magnetoresistor transistor to prevent interaction between the silicon magnetoresistor transistor and other devices;

the isolation groove (5) is n⁺And (4) carrying out type doping.

5. A sensor according to claim 1, characterized in that in the first mass (m)₁) And a second mass (m)₂) A first middle beam (L) is arranged between the two₉) And a second intermediate beam (L)₁₀)，

The first intermediate beam (L)₉) And a second intermediate beam (L)₁₀) Are all connected with the first mass block (m)₁) And a second mass (m)₂) Is vertically arranged.

6. Sensor according to claim 5, characterized in that the first mass (m)₁) And a second mass (m)₂) Are all equal to the maximum thickness of the magnetic field/acceleration integrated sensor;

the first single L-shaped beam (L)₁) To eighth single L-shaped beam (L)₈) A first intermediate beam (L)₉) And a second intermediate beam (L)₁₀) Are all the same as the thickness of the device layer (1).

7. Sensor according to claim 5, characterized in that in the first single L-shaped beam (L)₁) Second single L-shaped beam (L)₂) Third single L-shaped beam (L)₃) And a fourth single L-shaped beam (L)₄) Are respectively provided with a first piezoresistor (R) in the x-axis direction_x1) And a second piezoresistor (R) in the x-axis direction_x2) And a third piezoresistor (R) in the x-axis direction_x3) And a fourth varistor (R) in the x-axis direction_x4)；

In the fifth single L-shaped beam (L)₅) Sixth single L-shaped beam (L)₆) Seventh single L-shaped beam (L)₇) And eighth single L-shaped beam (L)₈) Are respectively provided with a first piezoresistor (R) in the y-axis direction_y1) And a second piezoresistor (R) in the y-axis direction_y2) And a third piezoresistor (R) in the y-axis direction_y3) And a fourth varistor (R) in the y-axis direction_y4)；

At the first intermediate beam (L)₉) And a first mass (m)₁) And a second mass (m)₂) The root parts of the joints are respectively provided with a first piezoresistor (R) in the z-axis direction_z1) And a second piezoresistor (R) in the z-axis direction_z2)；

At the second intermediate beam (L)₁₀) And a first mass (m)₁) And a second mass (m)₂) The root parts of the joints are respectively provided with a third piezoresistor (R) in the z-axis direction_z3) And a fourth piezoresistor (R) in the z-axis direction_z4)。

8. The sensor of claim 7, wherein the piezoresistors in the x-axis, y-axis and z-axis directions are all boron-doped nano-polysilicon thin film resistors.

9. A sensor according to claim 1, characterized in that a glass plate is also arranged below the acceleration sensor, which has a groove structure, bonded to the supporting silicon (2), so that the two masses of the acceleration sensor can move freely in the grooves.

10. The sensor of claim 9, wherein the glass sheet is a borosilicate glass sheet having a thickness of 0.5 to 1 mm.

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