Magnetic field sensor and manufacturing method thereof

Abstract

The invention discloses a magnetic field sensor which mainly comprises two silicon magneto-sensitive devices, a dielectric isolation wall, a dielectric isolation ring, a load resistor and the like. An emitter region, a collector region, a base region and the like of the magneto-sensitive device are all located on the upper surface of a silicon layer of an SOI (Silicon-On-Insulator) device, and the device is provided with a planar electrode structure. Magneto-sensitive devices arranged in opposite magnetic sensitive directions form a differential structure through a load resistor, and differential output of electric signals is achieved. The dielectric isolation wall and the dielectric isolation ring can effectively improve the performance of the sensor. The magnetic field sensor provided by the invention can realize measurement of an external magnetic field (a magnetic field perpendicular to the surface of a chip), the magnetic sensitivity cross interference is relatively low, the planar electrode structure manufacturing and packaging process is simple, and the magnetic field sensor has a prospect of batch production.

Description

Technical Field

[0001] The invention relates to a magnetic field sensor and a manufacturing method thereof, belonging to the technical field of sensors. Background Art

[0002] In the technical fields of geological exploration, non-destructive detection, automated production, etc., it is necessary to measure the magnetic field. Generally speaking, magnetic sensitive components have a certain magnetic sensitivity direction. For example, the Hall element can measure the magnetic field outside the chip plane, and the giant magnetoresistive sensor is sensitive to the magnetic field within the chip plane.

[0003] Therefore, in order to measure the spatial magnetic field vector, a variety of magnetic sensitive components are usually assembled to form a sensor. However, the magnetic sensitivity of different magnetic sensitive components varies, and the orthogonality of each magnetic sensitive direction is difficult to ensure during the assembly process, which also affects the performance of the sensor.

[0004] Among magnetic sensitive components, three-dimensional magnetic sensitive triodes can realize in-plane magnetic field measurement. In order to use the same magnetic sensitive device to achieve high-performance spatial magnetic field vector measurement, it is necessary to design a novel device structure, adjust the sensitive direction of the magnetic sensitive device so that it can complete the out-of-plane magnetic field measurement, and eliminate the cross interference caused by the magnetic field in the non-sensitive direction to the device. Summary of the invention

[0005] In order to solve the above problems, the inventors have conducted in-depth research and proposed a magnetic field sensor, which includes two silicon magnetic sensitive devices, a dielectric isolation wall, a dielectric isolation ring, and a load resistor.

[0006] The magnetic sensitive device is a planar structure magnetic sensitive triode with out-of-plane magnetic sensitive characteristics, and the sensor is manufactured on an SOI wafer.

[0007] The SOI wafer comprises an SOI device layer, an SOI substrate layer and a SiO2 insulating layer. The magnetic field sensor is arranged in the SOI device layer.

[0008] The magnetic sensitive region of the magnetic sensitive device includes an emitter region, a collector region and a base region.

[0009] The emitter region and the collector region are arranged opposite to each other on one side of the magnetic sensitive region and are both located on the upper surface of the SOI device layer. + Type heavily doped.

[0010] The base region is located on the other side of the magnetic sensitive region, and p is set at the base region. + type doping region, so that the metal electrode and the SOI device layer achieve good ohmic contact. +Electrodes are led out from the corresponding positions of the SOI doping region: emitter, collector and base. The metal electrode layer of the device is located on the upper surface of the SOI device layer, so the magnetic sensitive device has a planarized electrode structure. The present invention changes the magnetic sensitive direction of the device by adjusting the direction of carrier transmission in the magnetic sensitive region, so that the magnetic sensitive device has an out-of-plane magnetic sensitive characteristic, thereby realizing the sensor's measurement of out-of-plane magnetic fields.

[0011] In a preferred embodiment, a dielectric isolation wall is provided between the emitter region and the collector region, extending from the upper surface of the SOI device layer to the interior thereof, which can modulate the transport of carriers and reduce cross-interference.

[0012] The first magnetic sensor device includes an emitter region of the first magnetic sensor device, a collector region of the first magnetic sensor device, a base region of the first magnetic sensor device, and a base region of the first magnetic sensor device. + The second magnetic sensor comprises an emitter region of the second magnetic sensor, a collector region of the second magnetic sensor, a base region of the second magnetic sensor, and a p-type doped region of the base region of the second magnetic sensor. + Type doping region and dielectric isolation wall. Two magnetic sensors with the same structural parameters are symmetrically arranged on the surface of the sensor chip in opposite magnetic sensitive directions, and connected through collector load resistors and base load resistors to form a differential structure. The differential structure can make the magnetic sensitivity of the magnetic field sensor close to twice the magnetic sensitivity of a single magnetic sensor. In addition, this circuit structure can suppress zero drift, improve the temperature characteristics of the sensor, and reduce the cross-magnetic sensitivity of the two magnetic sensors.

[0013] The two emitters of the magnetic field sensor are grounded to GND, and the two collectors are connected to the power supply V through the collector load resistor. DD And output the first output V out1 and the second output V out2 , the differential output electrical signal V out , the base is connected to the power supply V through the base load resistor DD .

[0014] In a preferred embodiment, the dielectric isolation ring penetrates the upper and lower surfaces of the SOI device layer and forms a plurality of isolation islands with the second SiO2 insulating layer in the buried layer. The isolation dielectric is preferably SiO2. The magnetic sensor, the collector load resistor and the base load resistor are respectively arranged in the corresponding isolation islands. The dielectric isolation ring can effectively suppress the mutual influence between the components in the differential structure and improve the sensor performance.

[0015] The present invention also provides a method for manufacturing a magnetic field sensor, comprising the following steps:

[0016] S1. Clean the SOI wafer, perform zero-pass photolithography, and dry-etch the alignment mark on the upper surface of the SOI wafer;

[0017] S2. Clean the SOI wafer, perform photolithography once, photolithography isolation grooves on the upper surface of the SOI device layer, thermally grow a dielectric layer, make dielectric isolation rings and isolation walls, preferably SiO2, and perform a planarization process on the upper surface of the device layer;

[0018] S3. Secondary photolithography, photolithography load resistor window, injection of n - type impurity ions, preferably phosphorus ions;

[0019] S4. Three times of photolithography, photolithography of collector window, implantation of n + type impurity ions, preferably phosphorus ions;

[0020] S5. Four times of photolithography, photolithography of the emitter window and the load resistor lead hole window, and injection of n + type impurity ions, preferably phosphorus ions;

[0021] S6. Five times of photolithography, implantation of p + type impurity ions, preferably boron ions, clean the SOI wafer, anneal at high temperature to redistribute the impurities, and make n - Type lightly doped collector load resistor and base load resistor, n + The collector and emitter regions of the heavily doped type and the p-type + Type doped region;

[0022] S7. Clean the SOI wafer, grow a SiO2 layer on the upper surface of the SOI device layer as the first SiO2 insulating layer, perform six photolithography steps, and etch lead holes on the insulating layer;

[0023] S8. Evaporation of metal layer, seven times of photolithography, etching of metal layer, metal alloying process, formation of ohmic contact, and fabrication of interconnection lines and electrodes;

[0024] S9. Clean the SOI wafer, deposit a passivation layer on the upper surface of the SOI device layer, preferably a silicon nitride (Si3N4) layer, perform eight photolithography steps, etch the passivation layer, and form a bonding pad;

[0025] S10. Mid-term testing, dicing, and non-magnetized packaging.

[0026] The beneficial effects of the present invention include:

[0027] (1) Aiming at the problem of out-of-plane magnetic field measurement, the present invention designs a magnetic sensor with a planar electrode structure. By adjusting the transport direction of carriers inside the magnetic sensitive area, the magnetic sensor has out-of-plane magnetic sensitivity characteristics, thereby realizing the measurement of out-of-plane magnetic fields.

[0028] (2) The present invention designs and manufactures dielectric isolation walls and dielectric isolation rings to address the problem of suppressing cross-interference of magnetic sensitivity and isolating devices. The isolation wall effectively reduces the cross-interference of the in-plane magnetic field on the sensor by integrating the carrier transport direction in the magnetic sensitive area, and the dielectric isolation ring forms an isolation island in the SOI device layer, achieving a good isolation effect;

[0029] (3) Aiming at the problem of improving the characteristics of magnetic field sensors, the present invention provides a differential structure consisting of two magnetic sensitive devices with opposite magnetic sensitive directions and a load resistor. This structure can improve the magnetic sensitivity of the magnetic field sensor to the out-of-plane magnetic field, reduce the cross-interference of the magnetic sensitivity of the in-plane magnetic field, and improve the temperature characteristics.

[0030] Explanation of symbols

[0031] 1-SOI device layer;

[0032] 2-SOI substrate layer;

[0033] 31- a first SiO2 insulating layer;

[0034] 32- a second SiO2 insulating layer;

[0035] 33- third SiO2 insulating layer;

[0036] 41- an emission region of a first magnetic sensitive device;

[0037] 42- an emission region of a second magnetic sensitive device;

[0038] 51- collector region of the first magnetic sensor;

[0039] 52- collector region of the second magnetic sensor;

[0040] 61- a base region of a first magnetic sensor;

[0041] 62-a base region of a second magnetic sensitive device;

[0042] 71-p of the base region of the first magnetic sensor + Type doped region;

[0043] 72-p of the second magnetic sensor base region + Type doped region;

[0044] 8- medium isolation ring;

[0045] 9-Dielectric isolation wall

[0046] E1 - emitter of the first magnetic sensitive device;

[0047] E2-the emitter of the second magnetic sensitive device;

[0048] B1-base of the first magnetic sensitive device;

[0049] B2-base of the second magnetic sensitive device;

[0050] C1-collector of the first magnetic sensitive device;

[0051] C2-collector of the second magnetic sensitive device;

[0052] R b1 - a first base load resistor;

[0053] R b2 - a second base load resistor;

[0054] R L1 - first collector load resistor;

[0055] R L2 - Second collector load resistor;

[0056] V out1 - first output;

[0057] V out2 - Second output;

[0058] V DD -power supply;

[0059] GND-ground terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 A schematic diagram of the structure of a magnetic field sensor according to a preferred embodiment of the present invention is shown;

[0061] Figure 2 An equivalent circuit diagram of a magnetic field sensor according to a preferred embodiment of the present invention is shown;

[0062] Figure 3 A three-dimensional structure simulation model diagram of a magnetic field sensor according to a preferred embodiment of the present invention is shown;

[0063] Figure 4 The first magnetic sensor device in Example 1 is shown in FIG. C -V CE Characteristic simulation curve;

[0064] Figure 5 The second magnetic sensor device in Example 1 is shown in FIG. C -V CE Characteristic simulation curve;

[0065] Figure 6 The simulation curve of magnetic sensitivity characteristics of the magnetic field sensor in z direction in Example 1 is shown;

[0066] Figure 7The simulation curve of magnetic sensitivity characteristics of the magnetic field sensor in the y direction in Example 1 is shown;

[0067] Figure 8 The simulation curve of the magnetic sensitivity characteristic of the magnetic field sensor in the x direction in Example 1 is shown. DETAILED DESCRIPTION

[0068] The present invention will be further described in detail below through the accompanying drawings and embodiments. Through these descriptions, the characteristics and advantages of the present invention will become more clear and distinct.

[0069] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0070] According to a magnetic field sensor provided by the present invention, Figure 1 As shown, it includes a magnetic sensitive device, a dielectric isolation wall 9, a dielectric isolation ring 8 and a load resistor. The magnetic sensitive device has two, namely a first magnetic sensitive device and a second magnetic sensitive device.

[0071] The magnetic sensitive device is a planar structure magnetic sensitive triode with out-of-plane magnetic sensitive characteristics, and the magnetic sensitive device is manufactured on an SOI wafer.

[0072] The SOI wafer comprises an SOI device layer 1 , an SOI substrate layer 2 and a SiO 2 insulating layer, and the magnetic field sensor is arranged in the SOI device layer 1 .

[0073] The SiO2 insulating layer includes a first SiO2 insulating layer 31, a second SiO2 insulating layer 32 and a third SiO2 insulating layer 33, the SOI device layer 1 is located between the first SiO2 insulating layer 31 and the second SiO2 insulating layer 32, and the SOI substrate layer 2 is located between the second SiO2 insulating layer 32 and the third SiO2 insulating layer 33.

[0074] According to a preferred embodiment of the present invention, the SOI device layer 1 has a thickness of 5 μm and is preferably made of nearly intrinsic p-type single crystal silicon.

[0075] In the present invention, the emitter region, collector region and base region of the magnetic sensitive device are all arranged on the upper surface of the device layer 1. The emitter region and collector region arranged opposite to each other are located on one side of the magnetic sensitive region, and the base region is located on the other side of the magnetic sensitive region. + The distance between the emitter and collector regions is defined as the base length, and the distance between the emitter and collector regions is defined as the base width.

[0076] Preferably, the emission area is n +The type is heavily doped, formed by injecting phosphorus ions. The impurity ion concentration in the emitter region is 1E17 to 1E19 cm -3 , preferably 5E18 cm -3 The junction depth of the doped region is 0.5-3 μm, preferably 1 μm. The length of the emission region is 5-10 μm, the width is 5-10 μm, preferably a square with a length and width of 5 μm.

[0077] Preferably, the collector region is n + The type is heavily doped, formed by implanting phosphorus ions. The impurity ion concentration in the collector region is 1E17 to 1E19 cm -3 , preferably 1E18 cm -3 The junction depth of the doped region is 0.5-3 μm, preferably 1 μm. The collector region is 5-10 μm long, preferably 5 μm, and 2-5 μm wide, preferably 2.5 μm.

[0078] Preferably, a p + type doped region, so that the metal electrode and the SOI device layer 1 achieve good ohmic contact.

[0079] Preferably, the p + The p-type doped region is formed by implanting boron ions. + The impurity ion concentration in the type doped region is 1E15~1E16 cm -3 , preferably 1E15 cm -3 , the junction depth of the doped region is 0.5 to 1 μm, preferably 1 μm. + The type doped region has a length of 5 to 30 μm, preferably 10 μm, and a width of 2 to 5 μm, preferably 5 μm.

[0080] Preferably, the length of the base region is 30 to 60 μm, preferably 40 μm, and the width of the base region is 30 to 60 μm, preferably 40 μm.

[0081] According to the present invention, electrodes are respectively drawn out at corresponding positions of the emitter region, the collector region and the p+ type doping region to form an emitter, a collector and a base.

[0082] According to the present invention, the magnetic sensitive area structure adjusts the magnetic sensitive direction of the magnetic sensitive device from the in-plane direction (parallel to the chip surface) to the out-of-plane direction (perpendicular to the chip surface) by modulating the carrier transport direction when the device is working, so that the device can measure the out-of-plane magnetic field, breaking through the limitation of the magnetic sensitive device structure on its function.

[0083] In the present invention, the dielectric isolation wall is arranged between the emitter region and the collector region, and the isolation dielectric is preferably SiO2. The depth of the isolation wall is 1 to 5 μm, preferably 3 μm, the length is 5 to 10 μm, preferably 10 μm, and the thickness is 1 to 3 μm, preferably 2 μm. A conductive area is reserved between the dielectric isolation wall and the second SiO2 insulating layer 32.

[0084] According to the present invention, the dielectric isolation wall can block carriers whose motion trajectories are deflected due to the influence of the in-plane magnetic field, reduce the influence of the magnetic field in the non-sensitive direction on the magnetic sensitive device, and reduce the cross interference suffered by the magnetic sensitive device.

[0085] Preferably, the dielectric isolation wall is adjacent to the emission region, so as to improve the modulation efficiency of the dielectric isolation wall on carriers.

[0086] In the present invention, the first magnetic sensor and the second magnetic sensor are arranged in opposite magnetic sensitive directions, and ... L and the base load resistor R b The connections form a differential structure.

[0087] Specifically, the emitter E1 of the first magnetic sensor device and the emitter E2 of the second magnetic sensor device are both grounded GND, and the base B1 of the first magnetic sensor device is connected by a first base load resistor R b1 Connect power supply V DD The base B2 of the second magnetic sensitive device is connected by the second base load resistor R b2 Connect power supply V DD , the collector C1 of the first magnetic sensor device is connected by the first collector load resistor R L1 Connect power supply V DD And through the first output V out1 Output, the collector C2 of the second magnetic sensitive device is connected by the second collector load resistor R L2 Connect power supply V DD And through the second output V out2 Output, first output V out1 and the second output V out2 The differential output electrical signal V out , the equivalent circuit of the magnetic field sensor is as follows Figure 2 shown.

[0088] In a preferred embodiment, the emitter region 41 of the first magnetic sensor device and the emitter region 42 of the second magnetic sensor device are adjacent to each other, the collector region 51 of the first magnetic sensor device and the collector region 52 of the second magnetic sensor device are separated from each other, and the base region 161 of the first magnetic sensor device and the base region 62 of the second magnetic sensor device, and the base region 63 of the first magnetic sensor device are adjacent to each other. + The p-type doping region 71 and the second magnetic sensor base region +The type doped region 72 is on the same side of the upper surface of the SOI device layer 1, the magnetic sensitive regions of the two magnetic sensitive devices are symmetrically distributed, and a straight line passing through the magnetic sensitive centers of the two devices is perpendicular to the symmetry axis between the two magnetic sensitive regions.

[0089] According to the present invention, the differential structure can make the magnetic sensitivity of the magnetic field sensor close to twice the magnetic sensitivity of a single magnetic sensitive device. In addition, the circuit structure can also suppress zero drift, improve the temperature characteristics of the sensor, and reduce the cross sensitivity of the two magnetic sensitive devices.

[0090] In a preferred embodiment, the collector load resistor R L and the base load resistor R b n - Type light doping, formed by implanting phosphorus ions. The impurity ion concentration is 5E14~5E15 cm -3 , preferably 5E14 cm -3 The resistance value is 1.0 to 3.0 kΩ, preferably 2.0 kΩ.

[0091] In the present invention, the dielectric isolation ring 8 is located in the SOI device layer 1 and penetrates the device layer. The isolation dielectric is preferably SiO2, with a depth of 1 to 5 μm, preferably 5 μm, and a thickness of 1 to 3 μm, preferably 1 μm.

[0092] In a preferred embodiment, the dielectric isolation ring 8 and the second SiO2 insulating layer 32 form six rectangular isolation islands in three rows and two columns. The first magnetic sensitive device and the second magnetic sensitive device are arranged inside the two isolation islands in the middle, i.e., the second row. The first collector load resistor R is arranged in the isolation islands in the front and rear rows. L1 , the second collector load resistor R L2 , the first base load resistor R b1 , the second base load resistor R b2 .

[0093] According to the present invention, the dielectric isolation ring 8 can regulate the distribution of impurities in the isolation island, block the mutual influence between the components of the magnetic field sensor, effectively isolate the two magnetic sensitive devices in the differential structure, and improve the performance of the magnetic field sensor.

[0094] In a preferred embodiment, a first SiO2 insulating layer 31 and a third SiO2 insulating layer 33 are respectively disposed on the upper surface of the SOI device layer 1 and the lower surface of the SOI substrate layer 2 to protect and insulate the sensor chip.

[0095] Furthermore, a Si3N4 layer is provided on the upper surface of the first SiO2 insulating layer 31 as a passivation layer to protect the sensor chip. The thickness of the passivation layer is 0.1-0.2 μm, preferably 0.1 μm. The passivation layer is etched at the corresponding position of the electrode to form a lead hole to facilitate the lead-out of the electrode.

[0096] The present invention also provides a method for manufacturing a magnetic field sensor, comprising the following steps:

[0097] S1. Clean the SOI wafer, perform zero-pass photolithography, and dry-etch the alignment mark on the upper surface of the SOI wafer;

[0098] S2. Clean the SOI wafer, perform photolithography once, photolithography isolation grooves on the upper surface of the SOI device layer, grow a SiO2 layer, and make dielectric isolation rings and isolation walls;

[0099] S3. Secondary photolithography, photolithography load resistor window, injection of n - Type phosphorus ion;

[0100] S4. Three times of photolithography, photolithography of collector window, implantation of n + Type phosphorus ion;

[0101] S5. Four times of photolithography, photolithography of the emitter window and the load resistor lead hole window, and injection of n + Type phosphorus ion;

[0102] S6. Five times of photolithography, implantation of p + type boron ions, clean the SOI wafer, anneal at high temperature, and make the collector load resistor, base load resistor, collector region, emitter region and p-type silicon wafer inside the base region respectively. + Type doped region;

[0103] S7. Clean the SOI wafer, grow a SiO2 insulating layer on the upper surface of the SOI device layer, perform six photolithography steps, and etch lead holes on the insulating layer;

[0104] S8. Evaporation of metal layer, seven times of photolithography, etching of metal layer, metal alloying process to form ohmic contact, and production of interconnection lines and electrodes;

[0105] S9. Clean the SOI wafer, deposit a silicon nitride (Si3N4) layer on the upper surface of the SOI device layer, make a passivation layer, perform eight photolithography steps, etch the passivation layer, and form a bonding pad;

[0106] S10. Mid-term testing, dicing, and non-magnetized packaging.

[0107] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0108] Example

[0109] Construct a three-dimensional structure simulation model of the magnetic field sensor, such as Figure 3 As shown, the magnetic field sensor includes a magnetic sensitive device, a dielectric isolation wall 9, a dielectric isolation ring 8 and a load resistor. The magnetic sensitive device has two, namely a first magnetic sensitive device and a second magnetic sensitive device. Figure 1 As shown, the dielectric isolation wall is set between the emitter area and the collector area, the emitter E1 of the first magnetic sensor device and the emitter E2 of the second magnetic sensor device are both grounded GND, and the base B1 of the first magnetic sensor device is connected by the first base load resistor R b1 Connect power supply V DD The base B2 of the second magnetic sensitive device is connected by the second base load resistor R b2 Connect power supply V DD , the collector C1 of the first magnetic sensor, the first collector load resistor R L1 , connect power supply V DD And through the first output V out1 Output, the collector C2 of the second magnetic sensitive device is connected by the second collector load resistor R L2 Connect power supply V DD And through the second output V out2 Output, first output V out1 and the second output V out2 The differential output electrical signal V out .

[0110] The electrical characteristics and magnetic sensitivity characteristics of the three-dimensional structure simulation model of the magnetic field sensor are simulated and analyzed.

[0111] The I of the first magnetic sensor and the second magnetic sensor in the differential structure of the magnetic field sensor C -V CE At room temperature (T = 300K) and without an external magnetic field, the following conditions are set: collector voltage V CE The range is 0~6V, the step size is 0.2V, and the base current I B The range is 0~5mA, and the step length is 1mA. The I C -V CE The characteristic curves are as follows Figure 4 and Figure 5 shown.

[0112] As can be seen from the figure, the base current I B When the collector current I c As the collector voltage V CE increases with the increase of CE When it reaches a certain value, the device output tends to saturate. c The change tends to be gentle. Collector voltage V CE When the collector current I c With the base current I B In I B =5mA, V CE =6V, the collector current I of the first magnetic sensor and the second magnetic sensor C1 and I C2 The maximum value is 1.88 mA, which means that the current amplification factor β of the magnetic sensor is less than 1, and the two magnetic sensors in the differential structure have a high consistency of electrical characteristics.

[0113] Simulate the magnetic sensitivity of the magnetic field sensor model. At room temperature (T = 300K), set the following conditions: collector voltage V CE is 6V, the base current I B The current is 5 mA, and a magnetic field of -300 to 300 mT is applied in the x, y, and z directions, with a step size of 50 mT. L1 =R L2 =2kΩ, the simulation results show that the voltage output characteristic curves of the magnetic field sensor under the influence of magnetic fields in the x, y, and z directions are as follows: Figure 6 , Figure 7 and Figure 8 shown.

[0114] Depend on Figure 6 It can be seen that the output voltage of the magnetic field sensor changes linearly with the change of the magnetic field in the z direction. The magnetic field sensor has positive and negative magnetic sensitivity characteristics, and the positive and negative magnetic sensitivity are highly consistent. When the z-direction applied magnetic field changes in the range of -300 to 300mT, the magnetic sensitivity of the magnetic field sensor is 1044.19mV / T. Figure 6 and Figure 7 It can be seen that the magnetic field in the x and y directions has little effect on the output voltage of the magnetic field sensor, and the sensor cross-magnetic sensitivity is low. After calculation, the cross-interference percentages of the magnetic field in the x and y directions on the sensor are 0% and 4.25% respectively.

[0115] The present invention has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve only as an illustration. On this basis, the present invention may be subjected to a variety of substitutions and improvements, all of which fall within the scope of protection of the present invention.

Claims

1. A magnetic field sensor, characterized in that: The invention comprises a magnetic sensitive device, a dielectric isolation wall, a dielectric isolation ring and a load resistor. The magnetic sensitive device has two magnetic sensitive devices, namely a first magnetic sensitive device and a second magnetic sensitive device.

2. The magnetic field sensor according to claim 1, wherein the magnetic sensitive region of the magnetic sensitive device comprises an emitter region, a collector region and a base region, wherein: The emitter region and collector region are oppositely arranged on one side of the magnetic sensitive region, the base region is located on the other side of the magnetic sensitive region, the electrode layer of the magnetic sensitive device is located on the upper surface of the silicon layer of the SOI device, and the magnetic sensitive device has a planarized electrode structure.

3. The magnetic field sensor according to claim 1, characterized in that: The dielectric isolation wall is arranged between the emission area and the collector area of ​​the magnetic sensitive device.

4. The magnetic field sensor according to claim 1, characterized in that: The two magnetic sensors are arranged in opposite magnetic sensitive directions and form a differential structure with the load resistor.

5. The magnetic field sensor according to claim 1, characterized in that: The dielectric isolation ring divides the silicon layer of the SOI device into multiple regions to form multiple isolation islands, and the magnetic sensitive regions and load resistors of the magnetic sensitive device are respectively arranged in different isolation islands.

6. According to the magnetic field sensor of claim 1, a method for manufacturing the magnetic field sensor is provided, characterized in that: The following steps are involved: S1. Clean SOI wafer, perform zero-pass photolithography, and etch alignment marks; S2. Clean the SOI wafer, perform photolithography once, perform photolithography on the isolation groove, grow the dielectric layer with thermal oxidation, and make the dielectric isolation ring and isolation wall; S3. Secondary photolithography, photolithography load resistor window, injection of n - Type impurity ions; S4. Three times of photolithography, photolithography of collector window, implantation of n + Type impurity ions; S5. Four times of photolithography, photolithography of the emitter window and the load resistor lead hole window, and injection of n + Type impurity ions; S6. Five times of photolithography, photolithography of base window, and implantation of p + type impurity ions, clean the SOI wafer, and perform high temperature annealing to form the collector load resistor, base load resistor, collector region, emitter region, and p-type impurity ions in the base region. + Type doped region; S7. growing an insulating layer on the upper surface of the SOI device layer, performing six photolithography steps, and etching lead holes on the insulating layer; S8. Evaporation of metal layer, seven times of photolithography, etching of metal layer, metal alloying process, formation of ohmic contact, and fabrication of interconnection lines and electrodes; S9. Deposit a passivation layer on the upper surface of the wafer, perform eight photolithography steps, etch the passivation layer, and make a bonding pad; S10. Mid-term testing, dicing, and non-magnetized packaging.

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