阅读说明：本技术 一种磁场/加速度集成传感器和集成化工艺方法 (Magnetic field/acceleration integrated sensor and integration process method ) 是由 赵晓锋 王颖 于志鹏 温殿忠 于 2019-09-20 设计创作，主要内容包括：本发明公开了一种磁场/加速度集成传感器和集成化工艺方法,所述传感器包括设置在同一芯片上的磁场传感器和加速度传感器,磁场传感器磁敏感单元包括硅磁敏三极管和霍尔磁场传感器,其中,霍尔磁场传感器以原位掺杂纳米硅薄膜nc-Si:H(n<Sup>+</Sup>)作为磁敏感层,加速度传感器敏感单元主要为原位掺杂的纳米多晶硅薄膜电阻,可实现对三维磁场和三轴加速度的同时测量。本发明基于微电子机械加工技术在SOI晶圆器件层上完成集成传感器芯片制作,并通过键合工艺和内引线压焊技术实现芯片封装,具有体积小、易于批量生产等特点。(The invention discloses a magnetic field/acceleration integrated sensor and an integrated process method, wherein the sensor comprises a magnetic field sensor and an acceleration sensor which are arranged on the same chip, a magnetic sensitive unit of the magnetic field sensor comprises a silicon magnetosensitive triode and a Hall magnetic field sensor, and the Hall magnetic field sensor is doped with a nano silicon film nc-Si in situ H (n + ) As a magnetic sensitive layer, the sensitive unit of the acceleration sensor is mainly an in-situ doped nano polycrystalline silicon thin film resistor, and the simultaneous measurement of a three-dimensional magnetic field and triaxial acceleration can be realized. The invention completes the manufacture of integrated sensor chip on SOI wafer device layer based on microelectronic machining technology, and through bonding process and inner lead pressure welding technologyThe chip packaging is realized, and the chip packaging structure has the characteristics of small volume, easiness in batch production and the like.)

1. A magnetic field/acceleration integrated sensor is characterized in that the sensor comprises 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.

2. The sensor according to claim 1, characterized in that the magnetic field/acceleration integrated sensor is based on an SOI wafer comprising a device layer (1), a supporting silicon (2) and a first silicon dioxide layer (3);

the thickness of the device layer (1) is 20-50 mu m, and the thickness of the supporting silicon (2) is 420-550 mu m.

3. The sensor according to claim 1, characterized in that the magnetic field sensor comprises four silicon magnetotransistors in a three-dimensional structure and one Hall magnetic field sensor (H) arranged on the device layer (1), wherein,

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.

4. The sensor of claim 3, 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.

5. The sensor of claim 1, wherein a suspended structure is etched in the middle of the acceleration sensor, and the suspended structure comprises a mass block in the center and four double-L-shaped beams on two sides of the mass block;

wherein the mass blocks have 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)。

6. An integrated process for the production of an integrated magnetic field/acceleration sensor, preferably for the production of an integrated magnetic field/acceleration sensor according to one of claims 1 to 5, characterized in that it comprises the following steps:

step 1, cleaning an SOI (silicon on insulator) sheet, photoetching for the zeroth time, and manufacturing a register mark on a device layer (1);

step 2, oxidizing for the first time, and growing thin oxygen on the device layer (1) to be used as an ion implantation buffer layer;

step 3, the first timePhotoetching, carrying out ion implantation on the upper surface of the device layer (1) to realize n⁺Carrying out type doping, and processing for 8-10 h at 600-1200 ℃ to form an isolation groove;

step 4, carrying out second photoetching, etching a load resistor window on the upper surface of the device layer (1), carrying out ion implantation, and carrying out n^-Carrying out type doping to form a load resistor;

step 5, carrying out third photoetching, etching a base region window on the upper surface of the device layer (1), carrying out ion implantation, and carrying out p⁺Heavily doping to form a base region;

step 6, annealing at high temperature to form impurity distribution;

step 7, cleaning the SOI wafer, and growing a silicon dioxide layer on the upper surface of the device layer (1) by adopting a chemical vapor deposition method;

step 8, photoetching for the fourth time, and growing the phosphorus-doped nc-Si: H (n) in situ by adopting a chemical vapor deposition method⁺) To form phosphorus doped nc-Si: H (n)⁺) The film is used as a magnetic sensitive layer of the Hall magnetic field sensor;

step 9, cleaning the SOI wafer, and growing a boron-doped nano polycrystalline silicon film on the upper surface of the device layer (1) in situ by adopting a plasma chemical vapor deposition method;

and 10, carrying out fifth photoetching to etch the boron-doped nano polycrystalline silicon film on the upper surface of the device layer (1) to form 12 piezoresistors.

7. The method of claim 6, further comprising, after step 10, the steps of:

step 11, cleaning a silicon wafer, and growing a silicon dioxide layer on the upper surface of the device layer (1) by adopting a chemical vapor deposition method to serve as an insulating layer;

step 12, performing sixth photoetching, and etching a lead hole on the upper surface of the device layer (1);

step 13, performing seventh photoetching, and etching the window of the emission area of the C-shaped silicon cup and the mass block of the acceleration sensor on the back of the supporting silicon (2) by adopting a deep groove etching technology (ICP);

step 14, n is performed at the emitter window supporting the back of the silicon (2)⁺Forming an emitting region by type heavy doping, and then carrying out high-temperature annealing treatment;

step 15, cleaning a silicon wafer, and growing a metal aluminum layer on the upper surface of the device layer (1) and the lower surface of the supporting silicon (2) through magnetron sputtering to form a metal electrode; carrying out eighth photoetching, and reversely etching a metal aluminum layer on the upper surface of the device layer (1) to form a metal electrode;

step 16, cleaning the silicon wafer, and growing a silicon dioxide layer on the upper surface of the device layer (1) by adopting a chemical vapor deposition method to serve as a passivation layer;

step 17, performing ninth photoetching, and etching the passivation layer to form a pressure welding point; then cleaning the silicon wafer, and carrying out alloying treatment to form ohmic contact;

step 18, performing tenth photoetching and deep groove etching technology to etch the silicon wafer device layer (1) to the first silicon dioxide layer (3) and release the L-shaped beam structure;

and 19, bonding the SOI sheet with a borosilicate glass sheet with an overload protection structure.

8. The method according to claim 6, wherein in step 6, the high temperature annealing treatment is performed as follows: and (3) processing the mixture for 20-30 min in a vacuum environment at 600-1200 ℃.

9. The method according to claim 7, characterized in that in step 17 the alloying treatment is carried out as follows: treating at 300-500 deg.C for 10-50 min.

10. A magnetic field/acceleration integrated sensor prepared by the method of any one of claims 6 to 9.

Technical Field

The invention relates to the technical field of sensors, in particular to a monolithic integrated sensor for simultaneously detecting multiple physical quantities and multiple parameters, and particularly relates to a magnetic field/acceleration integrated sensor and an integrated process method.

Background

With the rapid development and application requirements of scientific technology, the sensor technology is emphasized, and nowadays, a single sensitive unit is developed into an integrated sensor capable of measuring multiple physical quantities and multiple directions simultaneously, and the integrated sensor is widely applied to the fields of modern industry, automotive electronics, aerospace, deep sea exploration and the like.

By analyzing the measurement principle of the space three-dimensional magnetic field and the acceleration in three directions, the result shows that the sensitive unit has great differences in the aspects of a sensitive mechanism, substrate material conductive type selection, a manufacturing process method and the like. At present, the magnetic field sensor which can be used for integration mainly comprises a Hall magnetic field sensor, a magnetosensitive diode, a magnetosensitive triode, a split drain field effect transistor (MAGFET) and the like, and the monocrystalline silicon substrate is preferably selected as a p-type conductive type for the magnetic field sensor which can be integrated by combining the consideration of main factors influencing the magnetosensitive characteristic of the magnetic field sensor; by analyzing the characteristics of the piezoresistive acceleration sensor, it is preferable that the single crystal silicon substrate be of n-type conductivity. In the prior art, incompatibility often exists in the process of manufacturing an integrated chip, so that a three-dimensional magnetic field sensor and a three-axis acceleration sensor are difficult to integrate.

Therefore, there is a need for a monolithic integrated magnetic field/acceleration sensor and an integrated process thereof, which can simultaneously measure a three-dimensional magnetic field and a three-axis acceleration and have good compatibility.

Disclosure of Invention

In order to overcome the above problems, the present inventors have conducted intensive studies and, as a result, found that: a monolithic integrated magnetic field/acceleration sensor is manufactured on an SOI wafer (p-type high-resistance Si of a device layer, the resistivity rho is more than or equal to 100 omega cm), a silicon magnetosensitive triode with a three-dimensional structure and a phosphorus-doped nano silicon film nc-Si: H (n is n⁺) Hall magnetic field sensing as a magnetically sensitive layerThe device is used as a sensitive unit of a magnetic field sensor, and the boron-doped nano polycrystalline silicon film resistor is used as a sensitive element of an acceleration sensor, so that the simultaneous measurement of a three-dimensional magnetic field and three-axis acceleration can be realized, and the invention is completed.

Specifically, the present invention aims to provide the following:

in a first aspect, a magnetic field/acceleration integrated sensor is provided, wherein the sensor comprises a magnetic field sensor and an acceleration sensor arranged on the same chip, so as to realize the simultaneous measurement of a three-dimensional magnetic field and three-axis acceleration.

In a second aspect, there is provided an integrated process method for a magnetic field/acceleration integrated sensor, preferably for preparing the magnetic field/acceleration integrated sensor of the first aspect, wherein the method comprises the following steps:

step 1, cleaning an SOI (silicon on insulator) sheet, photoetching for the zeroth time, and manufacturing a register mark on a device layer 1;

step 2, oxidizing for the first time, and growing thin oxygen on the device layer 1 to be used as an ion implantation buffer layer;

step 3, carrying out first photoetching, and carrying out ion implantation on the upper surface of the device layer 1 to realize n⁺Carrying out type doping, and processing for 8-10 h at 600-1200 ℃ to form an isolation groove;

step 4, carrying out second photoetching, etching a load resistor window on the upper surface of the device layer 1, carrying out ion implantation, and carrying out n^-Carrying out type doping to form a load resistor;

step 5, carrying out third photoetching, etching a base region window on the upper surface of the device layer 1, carrying out ion implantation, and carrying out p⁺Heavily doping to form a base region;

step 6, annealing at high temperature to form impurity distribution;

step 7, cleaning the SOI wafer, and growing a silicon dioxide layer on the upper surface of the device layer 1 by adopting a chemical vapor deposition method;

step 8, photoetching for the fourth time, and growing the phosphorus-doped nc-Si: H (n) in situ by adopting a chemical vapor deposition method⁺) To form phosphorus doped nc-Si: H (n)⁺) The film is used as a magnetic sensitive layer of the Hall magnetic field sensor;

step 9, cleaning the SOI wafer, and growing a boron-doped nano polycrystalline silicon film on the upper surface of the device layer 1 in situ by adopting a plasma chemical vapor deposition method;

and step 10, carrying out fifth photoetching to etch the boron-doped nano polycrystalline silicon film on the upper surface of the device layer 1 to form 12 piezoresistors.

In a third aspect, there is provided a magnetic field/acceleration integrated sensor prepared by the method of the second aspect.

The invention has the advantages that:

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

(2) the magnetic field/acceleration integrated sensor provided by the invention has the advantages that the selection device layer is p-type<100>The SOI wafer of crystal orientation high-resistance monocrystalline silicon is used as a substrate, and a Hall magnetic field sensor in a magnetic sensitive unit of the magnetic field sensor is doped with a nano silicon film nc-Si in situ⁺) As the magnetic sensitive layer, the sensitive unit of the acceleration sensor is mainly an in-situ doped nano-polysilicon thin film resistor, so that the problem that the substrate conduction types of two different physical quantity measuring sensitive units are different is solved;

(3) the integrated process method of the magnetic field/acceleration integrated sensor provided by the invention realizes the chip process manufacturing of the magnetic field/acceleration sensor based on the MEMS technology and the in-situ doping CVD method, realizes the chip packaging through the bonding process and the inner lead pressure welding technology, and has the characteristics of small volume, easy batch production and the like.

Drawings

FIG. 1 shows a schematic front view of a magnetic field/acceleration integrated sensor in accordance with a preferred embodiment of the present invention;

FIG. 2 shows a schematic back side view of a magnetic field/acceleration integrated sensor in accordance with a preferred embodiment of the present invention;

FIG. 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;

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

FIGS. 6 a-c show experimental characteristics of a magnetic field sensor according to a preferred embodiment of the present invention along the x-axis, y-axis and z-axis directions;

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

The reference numbers illustrate:

1-a device layer; 2-supporting silicon; 3-a first silicon dioxide layer; 4-a second silicon dioxide layer; 5-an isolation groove; 6-a metallic aluminum layer; an H-Hall magnetic field sensor; SMST 1-first silicon magnetosensitive triode; SMST 2-second silicon magnetosensitive triode; SMST 3-third silicon magnetosensitive triode; SMST 4-fourth silicon magnetosensitive triode; b is₁-a first base; b is₂-a second base; b is₃-a third base; b is₄-a fourth base; c₁-a first current collector; c₂-a second current collector; c₃-a third collector electrode; c₄-a fourth collector electrode; e₁-a first emitter; e₂-a second emitter; e₃-a third emitter; e₄-a fourth emitter; r_L1-a first collector load resistance; r_L2-a second collector load resistance; r_L3-a third collector load resistance; r_L4-a fourth collector load resistance; v₁-an x-axis first output voltage; v₂-an x-axis second output voltage; v₃-a y-axis first output voltage; v₄-a y-axis second output voltage; v_DD-a power source; GND-ground; i is_H1-a first control current pole; i is_H2-a second control current pole; v_H1-a first hall output; v_H2-a second hall output; r_H1-a first equivalent resistance; r_H2-a second equivalent resistance; r_H3-a third equivalent resistance; r_H4-a fourth equivalent resistance; m is₁-a first mass; m is₂-a second mass; l is₁-a first single L-beam; l is₂-a second single L-beam; l is₃-a third single L-beam; l is₄-a fourth single L-beam; l is₅-a fifth single L-beam; l is₆-sixth single L-formA beam; l is₇-a seventh single L-beam; l is₈-an eighth single L-beam; l is₉-a first intermediate beam; l is₁₀-a second intermediate beam; r_x1-a first piezo-resistor in x-direction; r_x2-a second piezo-resistor in the x-axis direction; r_x3-a third piezo-resistor in the x-axis direction; r_x4-a fourth piezo-resistor in the x-direction; r_y1-a y-axis direction first piezo-resistor; r_y2-a second piezoresistor in the y-axis direction; r_y3-a third varistor in the y-direction; r_y4-a fourth varistor in the y-direction; r_z1-a first piezo-resistor in z-direction; r_z2-a second piezoresistor in the z-axis direction; r_z3-a third piezo-resistor in z-direction; r_z4-a fourth piezoresistor in the z-axis direction; v_xout1-an x-axis first output voltage; v_xout2-an x-axis second output voltage; v_yout1-a y-axis first output voltage; v_yout2-a y-axis second output voltage; v_zout1-a z-axis first output voltage; v_zout2-a z-axis second output voltage; and the delta R is the relative variation of the resistance value of the resistor when the chip is influenced by external acceleration or a magnetic field.

Detailed Description

The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The features and advantages of the present invention will become more apparent from the description. In which, although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The invention provides a magnetic field/acceleration integrated sensor, which comprises a magnetic field sensor and an acceleration sensor which are integrated on the same chip, as shown in figure 1, so that the simultaneous measurement of a three-dimensional magnetic field and three-axis acceleration is realized.

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

The inventor researches and discovers that compared with the traditional silicon chip, the device manufactured on the SOI chip has smaller parasitic capacitance and can improve the speed of the device.

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

Wherein the resistivity p of the device layer is greater than 100 Ω -cm.

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

Preferably, a first silicon dioxide layer 3 is arranged between the device layer 1 and the support silicon 2, and the thickness of the first silicon dioxide layer 3 is 500 nm-800 nm.

The inventor researches and discovers that in the process of monolithically integrating a three-dimensional magnetic field sensor and a three-axis acceleration sensor, the monolithic integrated magnetic field/acceleration sensor is manufactured on an SOI (silicon on insulator) sheet of which the device layer is p-type <100> crystal orientation high-resistance monocrystalline silicon, so that the three-dimensional magnetic field and the three-axis acceleration can be simultaneously measured.

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

According to a preferred embodiment of the present invention, as shown in fig. 1, the magnetic field sensor comprises four silicon magnetotransistors in a three-dimensional structure disposed on a device layer 1 and a hall magnetic field sensor H, wherein,

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.

In a further preferred embodiment, the hall magnetic field sensor is arranged at the center of the magnetic field sensor, and the four silicon magnetotriodes are arranged at the edge of the magnetic field sensor.

The p-type high-resistance monocrystalline silicon is used as the device layer and the substrate, so that the sensitivity of the magnetic field sensor is improved.

In a further preferred embodiment, 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,

wherein the first silicon magnetic sensing triode SMST1 and the second silicon magnetic sensing triode SMST2 are symmetrically arranged along the x axis of the magnetic field sensor at the two sides of the center of the three-dimensional magnetic field sensor chip,

and the third silicon magnetic sensing triode SMST3 and the fourth silicon magnetic sensing triode SMST4 are symmetrically arranged at two sides of the center of the three-dimensional magnetic field sensor chip along the y axis of the magnetic field sensor.

Preferably, the first silicon magnetic sensing triode SMST1 and the second silicon magnetic sensing triode SMST2 are arranged in the direction opposite to the magnetic sensing direction of the y axis, and the third silicon magnetic sensing triode SMST3 and the fourth silicon magnetic sensing triode SMST4 are arranged in the direction opposite to the magnetic sensing direction of the x axis.

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

In a further preferred embodiment, metal Al layers 6 are deposited on the surfaces of the base region, the collector region and the emitter region to form a base electrode, a collector electrode and an emitter electrode of the silicon magnetic sensitive triode respectively.

As shown in fig. 1, the first base B of the first silicon magnetosensitive triode SMST1 is formed on the upper surface of the device layer 1₁And a first collector electrode C₁The second base B of the second silicon magnetic sensitive triode SMST2₂And a second collector electrode C₂The third base B of the third silicon magnetic sensitive triode SMST3₃And a third collector electrode C₃The fourth base B of the fourth silicon magnetic sensitive triode SMST4₄And a fourth collector electrode C₄。

As shown in fig. 2, a first emitter E of a first silicon triode SMST1 is formed on the lower surface of the support silicon 2₁A second emitter E of a second silicon magnetoresistor SMST2₂A third emitter E of a third silicon magnetosensitive triode SMST3₃A fourth emitter E of a fourth silicon triode SMST4₄。

In a further preferred embodiment, a collector load resistor is formed on the upper surface of the device layer 1 on the side of the collector of the silicon magnetosensitive triode.

Wherein, as shown in fig. 1, the first collector C of the first silicon magnetosensitive triode SMST1₁A first collector load resistor R is formed on one side_L1Second collector C of second silicon magnetic sensitive triode SMST2₂One side of the second collector load resistor R_L2Third collector C of third silicon magnetosensitive triode SMST3₃A third collector load resistor R is formed on one side_L3Fourth collector C of fourth silicon magnetosensitive triode SMST4₄A fourth collector load resistor R is formed on one side_L4。

Preferably, the four collector load resistors are all n^-And (4) carrying out type doping.

According to a preferred embodiment of the present invention, as shown in fig. 1 and 3, the first collector C of the first silicon triode SMST1₁And a first collector load resistor R_L1Connected to form a first output voltage V on x-axis at the junction₁，

A second collector C of the second silicon magnetic sensitive triode SMST2₂And a second collector load resistor R_L2Connected to form a second output voltage V on x-axis at the junction₂。

In a further preferred embodiment, the first base electrode B₁A second base electrode B₂A first collector load resistor R_L1And a second collector load resistance R_L2Are connected with a power supply V together at the other end_DD。

The emitter of the first silicon magnetic sensing triode SMST1 and the emitter of the second silicon magnetic sensing triode SMST2 are connected to the ground GND in common.

In the invention, two silicon magnetosensitive triodes (SMST1 and SMST2) and two collector load resistors (R) which are respectively connected with each other_L1And R_L2) A first differential test circuit is constructed for detecting the magnetic field in the x-axis direction.

According to a preferred embodiment of the present invention,a third collector C of the third silicon magnetic sensitive triode SMST3₃And a third collector load resistor R_L3Connected to form a first y-axis output voltage V at the junction₃，

A fourth collector C of the fourth silicon magnetic sensitive triode SMST4₄And a fourth collector load resistor R_L4Connected to form a second y-axis output voltage V at the junction₄。

In a further preferred embodiment, the third base electrode B₃A fourth base electrode B₄A third collector load resistor R_L3And a fourth collector load resistance R_L4Are connected with a power supply V together at the other end_DD。

The emitter of the third silicon magnetic sensing triode SMST3 and the emitter of the fourth silicon magnetic sensing triode SMST4 are connected with the ground GND in common.

In the invention, two silicon magnetosensitive triodes (SMST3 and SMST4) and two collector load resistors (R) which are respectively connected with each other_L3And R_L4) A second differential test circuit is constructed for detecting the magnetic field in the y-axis direction.

According to a preferred embodiment of the invention, the hall magnetic field sensor H comprises a magnetically sensitive layer, two control current poles and two hall outputs, wherein,

the two control current poles are the first control current pole I_H1And a second control current electrode I_H2The two Hall output ends are a first Hall output end V_H1And a second Hall output terminal V_H2。

In a further preferred embodiment, as shown in fig. 3, the first control current pole I_H1And a first Hall output terminal V_H1Is equivalent to a first equivalent resistance R_H1First control current pole I_H1And a second Hall output terminal V_H2Is equivalent to a second equivalent resistance R_H2Second control current pole I_H2And a first Hall output terminal V_H1Is equivalent to a third equivalent resistor R_H3Second control current pole I_H2And a second Hall output terminal V_H2Is equivalent to a fourth equivalent resistance R_H4。

In a further preferred embodiment, as shown in fig. 3, the first equivalent resistance R_H1And a third equivalent resistor R_H3Connected to form a first output voltage V of z-axis_z1Said second equivalent resistance R_H2And a fourth equivalent resistance R_H4Connected to form a z-axis second output voltage V_z2。

In the present invention, four equivalent resistances R_H1、R_H2、R_H3And R_H4A wheatstone bridge configuration is formed for sensing the magnetic field in the z-direction.

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

In the invention, the phosphorus-doped nano silicon film is manufactured on the upper surface of the device layer 1 in an in-situ doping mode, so that the magnetic sensitivity characteristic of a Hall magnetic field sensor in a three-dimensional magnetic field sensor can be obviously improved, and the detection consistency in the three directions of an x axis, a y axis and a z axis can be ensured.

In combination with the main factors affecting the characteristics of the hall magnetic field sensor, when the doped phosphorus is too much, the magnetic sensitivity is reduced, and when the doped phosphorus is too little, the output impedance is too much affected.

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

Due to the multi-directionality of the spatial three-dimensional magnetic field, two or more magnetic sensitive components are required to be combined for use, and in the prior art, a silicon magnetic sensitive triode is adopted for measuring the magnetic field in the x-axis direction and the y-axis direction so as to ensure the detection consistency in the x-axis direction, the y-axis direction and the z-axis direction.

According to a preferred embodiment of the present invention, an isolation trench 5 is formed on the device layer 1 around each silicon magnetosensitive transistor to prevent the silicon magnetosensitive transistor from interacting with other devices.

In a further preferred embodiment, the isolation trenches 5 are n⁺And (4) carrying out type doping.

The inventor researches and discovers that in a device layer (A)<100>Crystal orientation high resistance p type monocrystalline silicon) to form n⁺The type-doped isolation groove enables the inside and the outside of the isolation groove to be P-type, the isolation groove and the inner and outer contact surfaces of the device layer form a PN junction, and the PN junction has a one-way conductive characteristic, so that one contact surface (the inner contact surface or the outer contact surface) is always not conducted, and thus, each silicon magnetic sensitive triode is successfully isolated from other devices, the conduction between the devices is prevented, the mutual interference is avoided, and the stability of the sensor is improved.

According to a preferred embodiment of the present invention, as shown in fig. 1, a suspension structure is etched in the middle of the acceleration sensor, and the suspension structure includes a mass block located in the center and four double L-shaped beams located on two sides of the mass block;

wherein, the mass block has two, respectively is the first mass block m₁And a second mass m₂；

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 L₁Second single L-shaped beam L₂Third single L-shaped beam L₃Fourth single L-shaped beam L₄Fifth single L-shaped beam L₅Sixth single L-shaped beam L₆Seventh single L-shaped beam L₇And an eighth single L-shaped beam L₈。

Preferably, the first single L-shaped beam L₁Second single L-shaped beam L₂Fifth single L-shaped beam L₅And a seventh single L-shaped beam L₇The X-axis or Y-axis direction center line is arranged on one side of the X-axis or Y-axis direction center line and is parallel to the X-axis or Y-axis direction center line;

the third single L-shaped beam L₃Fourth single L-shaped beam L₄Sixth single L-shaped beam L₆And an eighth single L-shaped beam L₈The X-axis or Y-axis direction center line is arranged on the other side of the X-axis or Y-axis direction center line and is parallel to the X-axis or Y-axis direction center line.

In the invention, each double L-shaped beam is arranged into two single L-shaped beams which are connected to form eight single L-shaped beam structures, so that the sensitivity in the x-axis direction and the y-axis direction can be obviously improved, the sensitivity in the x-axis direction and the sensitivity in the y-axis direction are close to the sensitivity in the z-axis direction, and the sensitivity characteristics in all directions tend to be consistent.

In a further preferred embodiment, in the first mass m₁And a second mass m₂A first middle beam L is arranged between the two₉And a second intermediate beam L₁₀；

Preferably, the first mass m₁And a second mass m₂Are symmetrically arranged along the direction of the x axis or the direction of the y axis at the center of the acceleration sensor,

the first intermediate beam L₉And a second intermediate beam L₁₀Are symmetrically arranged along the direction of the x axis or the direction of the y axis at the center of the acceleration sensor,

the first intermediate beam L₉And a second intermediate beam L₁₀Are all connected with the first mass block m₁And a second mass m₂Is vertically arranged.

In a further preferred embodiment, the first mass m₁And a second mass m₂Are all equal to the maximum thickness of the magnetic field/acceleration integrated sensor;

the first single L-shaped beam L₁To eighth single L-shaped beam L₈First intermediate beam L₉And a second intermediate beam L₁₀Are all the same as the thickness of the device layer 1.

In the present invention, the thickness of the mass and the sensor are both the distance between the upper and lower surfaces along the z-axis direction.

According to a preferred embodiment of the invention, the first mass m is arranged in the first mass₁A second single L-shaped beam L is connected with one side of the first middle beam back to the second middle beam₂Fourth single L-shaped beam L₄Seventh single L-shaped beam L₇And an eighth single L-shaped beam L₈；

At the second mass m₂A first single L-shaped beam L is connected with one side of the first middle beam back to the second middle beam₁Third single L-shaped beam L₃Fifth, fifthSingle L-shaped beam L₅And a sixth single L-shaped beam L₆。

The L-shaped beam, the middle beam and the mass block jointly form a structure of the triaxial acceleration sensor.

In a further preferred embodiment, the first single L-shaped beam L₁Second single L-shaped beam L₂Third single L-shaped beam L₃And a fourth single L-shaped beam L₄Are respectively provided with a first piezoresistor R in the x-axis direction_x1And a second piezoresistor R in the x-axis direction_x2And a third piezoresistor R in the x-axis direction_x3And a fourth varistor R in the x-axis direction_x4；

Wherein, the first piezoresistor R in the x-axis direction_x1And a second piezoresistor R in the x-axis direction_x2And a third piezoresistor R in the x-axis direction_x3And a fourth varistor R in the x-axis direction_x4Are arranged parallel to each other.

In a further preferred embodiment, as shown in fig. 1 and 4, the first piezoresistor R in the x-axis direction_x1And a second varistor R in the x-axis direction_x2Is connected to form a first output voltage V of x-axis at the junction_xout1(ii) a The third piezoresistor R in the x-axis direction_x3And a fourth varistor R in the x-axis direction_x4Is connected to form a second output voltage V of x-axis at the junction_xout2；

Preferably, the first piezoresistor R in the x-axis direction_x1And the other end of the first varistor R and the x-axis direction of the second varistor R_x4Are connected with a power supply V together at the other end_DDThe second piezoresistor R in the x-axis direction_x2And the other end of the third varistor R in the x-axis direction_x3The other ends of the first and second electrodes are commonly Grounded (GND).

Wherein the first single L-shaped beam L₁A second single L-shaped beam L₂And a third single L-shaped beam L₃And a fourth single L-shaped beam L₄Four piezoresistors (R) of the root_x1、R_x2、R_x3、R_x4) A first wheatstone bridge is formed for detecting acceleration in the x-axis direction. Under the action of acceleration along the x-axis direction, the output end V of the Wheatstone bridge_xout1And V_xout2The change can realize the detection of the acceleration of the x axis.

According to a preferred embodiment of the present invention, the fifth single L-shaped beam L₅Sixth single L-shaped beam L₆Seventh single L-shaped beam L₇And an eighth single L-shaped beam L₈The roots of the two are respectively provided with a first piezoresistor R in the y-axis direction_y1And a second piezoresistor R in the y-axis direction_y2And a third piezoresistor R in the y-axis direction_y3And a fourth varistor R in the y-axis direction_y4，

Wherein, the first piezoresistor R in the y-axis direction_y1And a second piezoresistor R in the y-axis direction_y2And a third piezoresistor R in the y-axis direction_y3And a fourth varistor R in the y-axis direction_y4Are arranged parallel to each other.

In a further preferred embodiment, the first piezoresistor R in the y-axis direction_y1And a second piezoresistor R in the y-axis direction_y2Is connected with each other, and a first output voltage V of a y axis is formed at the connection part_yout1(ii) a Third piezoresistor R in y-axis direction_y3And a fourth varistor R in the y-axis direction_y4Is connected with one end of the first output voltage source, and a y-axis second output voltage V is formed at the connection part_yout2。

In a further preferred embodiment, the first varistor R is arranged in the y-direction_y1And the other end of the second varistor R and the y-axis direction of the fourth varistor R_y4Are connected with a power supply V together at the other end_DDSecond piezoresistor R in y-axis direction_y2And the other end of the third varistor R in the y-axis direction_y3The other ends of the first and second electrodes are commonly grounded.

Wherein, the fifth single L-shaped beam L₅Sixth single L-shaped beam L₆Seventh single L-shaped beam L₇And an eighth single L-shaped beam L₈Four piezoresistors (R) of the root_y1、R_y2、R_y3、R_y4) A second wheatstone bridge is formed for detecting acceleration in the y-axis direction. Under the action of acceleration along the y-axis direction, the output end V of the Wheatstone bridge_yout1And V_yout2And the detection of the acceleration of the y axis can be realized by changing the acceleration sensor.

A good according to the inventionIn an alternative embodiment, the first intermediate beam L₉And a first mass m₁And a second mass m₂The root parts of the joints are respectively provided with a first piezoresistor R in the z-axis direction_z1And a second piezoresistor R in the z-axis direction_z2；

At the second intermediate beam L₁₀And a first mass m₁And a second mass m₂The root parts of the joints are respectively provided with a third piezoresistor R in the z-axis direction_z3And a fourth piezoresistor R in the z-axis direction_z4；

Wherein the first piezoresistor R in the z-axis direction_z1And a second piezoresistor R in the z-axis direction_z2Are arranged in a mutually vertical way,

the third piezoresistor R in the z-axis direction_z3And a fourth piezoresistor R in the z-axis direction_z4Are arranged perpendicular to each other.

In a further preferred embodiment, the first piezoresistor R in the z-axis direction_z1And a second piezoresistor R in the z-axis direction_z2Is connected with one end of the first output voltage V, and a first output voltage V of a z axis is formed at the connection part_zout1(ii) a Third piezoresistor R in z-axis direction_z3And a fourth piezoresistor R in the z-axis direction_z4Is connected with one end of the first output voltage source, and a second output voltage V of a z axis is formed at the connection position_zout2。

In a further preferred embodiment, the first piezoresistor R in the z-axis direction_z1And the other end of the first varistor R and the z-axis direction of the second varistor R_z4Are connected with a power supply V together at the other end_DDSecond piezoresistor R in z-axis direction_z2And the other end of the third varistor R in the z-axis direction_z3The other ends of the first and second electrodes are commonly grounded.

Wherein, four piezoresistors (R) in the z-axis direction at the root parts of the first middle beam and the second middle beam_z1、R_z2、R_z3、R_z4) A third wheatstone bridge is formed for detecting acceleration in the z-axis direction. Under the action of acceleration along the z-axis direction, the output end V of the Wheatstone bridge_zout1And V_zout2The z-axis acceleration can be detected by changing the position of the sensor.

Where Δ R in fig. 4 represents the relative change amount of the resistance value of the resistor when the chip is affected by external acceleration or a magnetic field.

According to a preferred embodiment of the present invention, the piezoresistors 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 invention, when the magnetic field sensor and the acceleration sensor are manufactured in an integrated mode, the SOI wafer of p-type <100> crystal orientation high-resistance monocrystalline silicon is used as the substrate, the sensitivity of the piezoresistive acceleration sensor can be influenced to a certain extent, and in order to solve the compatibility problem, the p-type boron-doped nano polycrystalline silicon film resistor is preferably used as a sensitive element of the acceleration sensor so as to ensure the sensitivity of the acceleration sensor.

The research of the inventor finds that the boron-doped nano polycrystalline silicon film has more excellent piezoresistive characteristics than other conventional polycrystalline silicon films, has small temperature coefficient of strain factor and small temperature coefficient of resistance, and can realize pressure-sensitive test with high sensitivity and wide working temperature range. Therefore, the acceleration sensor can be ensured to have high sensitivity on the p-type substrate, and the monolithic 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 is 1E13^-3～1E15cm^-3。

The inventor researches and discovers that when the doping amount of boron is too high, heavy doping is formed, so that the resistivity of the piezoresistor is lower, and when the external acceleration acts, the piezoresistive coefficient is reduced, the output voltage of a Wheatstone bridge is lower, and the pressure-sensitive characteristic is influenced; when the doping amount of boron is too low, light doping is formed, so that the resistivity of the piezoresistor is higher, and when the external acceleration acts, the resistance value variation of the resistor is not obvious, the output voltage of the Wheatstone bridge is lower, and the voltage-sensitive characteristic is influenced.

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

According to a preferred embodiment of the invention, a glass plate is also arranged below the acceleration sensor, and the glass plate is provided with a groove structure and is in bonding connection with the supporting silicon 2, so that two masses of the acceleration sensor can freely move in the groove.

In a further preferred embodiment, the glass sheet is a borosilicate glass sheet and has a thickness of 0.5 to 1 mm.

According to the invention, the glass sheet has an overload protection function, so that the complicated process of thinning the mass block is avoided, and the mass block at the center of the acceleration sensor can freely move in the groove of the glass sheet.

The invention also provides an integrated process method of the magnetic field/acceleration integrated sensor, which is preferably used for preparing the magnetic field/acceleration integrated sensor, as shown in a-e in fig. 5, and the method comprises the following steps:

step 1, cleaning the SOI wafer (as shown in a in fig. 5), performing zeroth lithography (as a lithography process registration mark), and making a registration mark on the device layer 1.

The method comprises the following steps of cleaning a monocrystalline silicon substrate by adopting an RCA standard cleaning method, wherein the cleaning is carried out as follows: the SOI slice is boiled by concentrated sulfuric acid until white smoke is emitted, is washed by a large amount of 15 deionized water after being cooled, and is respectively washed by an electronic cleaning solution No. 1 APM (SC-1) and an electronic cleaning solution No. 2 HPM (SC-2), wherein the No. 1 solution comprises the following main components in volume ratio: ammonia water, hydrogen peroxide and water in a ratio of 1:1:5 (the concentration of ammonia water is 27 percent, and the concentration of hydrogen peroxide is 30 percent), wherein the main components and the volume ratio of the No. 2 solution are as follows: hydrochloric acid, hydrogen peroxide and water in a ratio of 1:1:5 (the concentration of hydrochloric acid is 37 percent and the concentration of hydrogen peroxide is 30 percent), cleaning twice respectively, then washing with a large amount of deionized water, and finally putting into a spin dryer for spin-drying.

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

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

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 monocrystalline silicon, and the thickness thereof is 420 to 550 μm, preferably 450 to 525 μm, and more preferably 475 to 500 μm.

Preferably, a first silicon dioxide layer 3 is arranged between the device layer 1 and the support silicon 2, and the thickness of the first silicon dioxide layer 3 is 500 nm-800 nm.

And 2, oxidizing for the first time, and growing thin oxygen on the device layer 1 to be used as an ion implantation buffer layer.

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

Step 3, carrying out first photoetching, etching an isolation groove window on the upper surface of the device layer 1, then carrying out phosphorus ion implantation, and carrying out n⁺And (3) carrying out type doping, and treating for 8-10 h at 600-1200 ℃ to form an isolation groove. (as shown in b in fig. 5).

According to a preferred embodiment of the present invention, n is⁺The doping concentration of the type doping is 5E14^-3～1E15cm^-3。

The inventors have found that PN junction isolation is facilitated with the above doping concentrations.

The annealing temperature and the vacuum treatment time have the advantages that the high-temperature annealing can activate impurity ions and eliminate damage caused by ion implantation, the vacuum treatment can prevent oxygen and other substances in the atmosphere from influencing the chip, if the annealing temperature is too low or the time is too short, the damage caused by ion implantation cannot be well eliminated, the ions cannot reach the substitution position, and the surface crystallization state is not good; if the annealing temperature is too high or the processing time is too long, the implanted ions may be displaced, and the dislocation and defect density are easily caused.

Step 4, carrying out second photoetching, etching a load resistor window on the upper surface of the device layer 1, injecting phosphorus ions, and carrying out n^-And (4) doping to form a load resistor.

Step 5, carrying out third photoetching, etching a base region window on the upper surface of the device layer 1, implanting boron ions, and carrying out p⁺And heavily doping to form a base region.

Wherein p is⁺Heavily doped type 1E13^-3～1E15cm^-3。

And 6, annealing at high temperature to form impurity distribution.

According to a preferred embodiment of the present invention, the high temperature annealing treatment is performed as follows: and (3) processing the mixture for 20-30 min in a vacuum environment at 600-1200 ℃.

The annealing temperature and the vacuum treatment time have the advantages that: the high-temperature annealing can activate impurity ions, and the vacuum treatment can prevent oxygen and other substances in the atmosphere from influencing the chip. If the annealing temperature is too low or the annealing time is too short, the damage of ion implantation cannot be well eliminated, ions cannot reach a substitution position, and the surface crystallization state is not good; too high an annealing temperature or too long a processing time may cause the implanted ions to be displaced, easily resulting in dislocation and defect densities.

And 7, cleaning the SOI wafer, and growing a silicon dioxide layer on the upper surface of the device layer 1 by adopting a chemical vapor deposition method.

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

Step 8, photoetching for the fourth time, and growing the phosphorus-doped nc-Si: H (n) in situ by adopting a chemical vapor deposition method⁺) To form phosphorus doped nc-Si: H (n)⁺) The thin film acts as the hall magnetic field sensor magnetically sensitive layer (shown as b in fig. 5).

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

In a further preferred embodiment, the doping amount of phosphorus is 5E13^-3～1E15cm^-3。

And 9, cleaning the SOI wafer, and growing the boron-doped nano polycrystalline silicon film on the upper surface of the device layer 1 in situ by adopting a Plasma Enhanced Chemical Vapor Deposition (PECVD) method.

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

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

In a still further preferred embodiment, the boron isThe doping amount is 1E13^-3～1E15cm^-3。

Step 10, performing fifth photoetching to etch the boron-doped nano-polysilicon film on the upper surface of the device layer 1 to form 12 piezoresistors (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 c in fig. 5).

And 11, cleaning the silicon wafer, and growing a silicon dioxide layer on the upper surface of the device layer 1 by adopting a chemical vapor deposition method to serve as an insulating layer.

Wherein the thickness of the grown silicon dioxide layer is 400-600 nm.

And step 12, carrying out sixth photoetching, and etching a lead hole on the upper surface of the device layer 1.

And step 13, performing seventh photoetching, and etching the window of the C-shaped silicon cup emission area and the mass block of the acceleration sensor chip on the back of the support silicon 2 by adopting a deep groove etching technology (ICP).

Wherein, a deep trench etching technology (ICP) is adopted to etch the first silicon dioxide layer 3.

Step 14, n is performed at the emitter window supporting the back of the silicon 2⁺And forming an emitter region by type heavy doping, and then carrying out high-temperature annealing treatment.

Wherein the high-temperature annealing comprises the following steps: and (3) processing the mixture for 20-30 min in a vacuum environment at 600-1200 ℃.

Step 15, cleaning the silicon wafer, and growing a metal aluminum layer on the upper surface of the device layer 1 and the lower surface of the support silicon 2 through magnetron sputtering to form a metal electrode layer; and then carrying out eighth photoetching to reversely etch a metal aluminum layer on the upper surface of the device layer 1 to form a metal electrode.

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

And step 16, cleaning the silicon wafer, and growing a silicon dioxide layer on the upper surface of the device layer 1 by adopting a chemical vapor deposition method to serve as a passivation layer.

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

Step 17, performing ninth photoetching, and etching the passivation layer to form a pressure welding point; the wafer is then cleaned and alloyed to form an ohmic contact (shown as d in figure 5).

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

And 18, performing tenth photoetching and deep trench etching (ICP) on the silicon wafer device layer 1, etching to the first silicon dioxide layer 3, and releasing the L-shaped beam structure (shown as e in figure 5).

And 19, bonding the SOI sheet with a borosilicate glass sheet with an overload protection structure.

The borosilicate glass sheet is provided with a groove structure and is in bonding connection with the supporting silicon 2, so that the two mass blocks of the acceleration sensor can freely move in the grooves.

Preferably, the thickness of the material is 0.5-1 mm.

In the invention, the manufacture of a monolithic three-dimensional magnetic field/three-axis acceleration sensor chip is completed on an SOI wafer device layer (p-type <100> crystal orientation high-resistance monocrystalline silicon) based on a micro-electro-mechanical system (MEMS) technology, the chip packaging is realized through a bonding process and an inner lead pressure welding technology, and the simultaneous measurement of the three-dimensional magnetic field and the three-axis acceleration can be realized. The magnetic field/acceleration integrated sensor prepared by the method has the characteristics of small volume and easiness in batch production.