阅读说明：本技术 一种内互联七电极低失调垂直霍尔磁传感器 (Internal interconnection seven-electrode low-offset vertical Hall magnetic sensor ) 是由 吕飞 张金 刘飞 于 2019-11-26 设计创作，主要内容包括：本发明公开了一种内互联七电极低失调垂直霍尔磁传感器,包括作为电子运动空间,结合霍尔效应产生霍尔电压,从而实现对磁场的探测的有源区；将有源区与外部金属层相连,用于恒流激励的施加,以及霍尔电压的输出的电极；以及采用芯片内部互联方式的互联线；所述电极为7个,分别为C1～C7,采用对称式分布；7个电极两两采用内部互联线相连,互联的两电极位于对称点两侧。通过两侧电流交换减小两侧非对称性带来的传感器失调。本发明内互联七电极低失调垂直霍尔磁传感器与传统的与电极垂直霍尔传感器相比失调电压降低到原来的9.8％,失调磁场降低到原来的11.7％。(The invention discloses an internal interconnection seven-electrode low-offset vertical Hall magnetic sensor, which comprises an active region, a Hall effect circuit and a control circuit, wherein the active region is used as an electronic motion space and generates Hall voltage by combining the Hall effect so as to realize detection of a magnetic field; an electrode connecting the active region with an external metal layer for application of constant current excitation and output of Hall voltage; and an interconnection line adopting a chip internal interconnection mode; the number of the electrodes is 7, the electrodes are respectively C1-C7 and are distributed symmetrically; the 7 electrodes are connected pairwise by adopting internal interconnection lines, and the two interconnected electrodes are positioned at two sides of the symmetrical point. Sensor offset due to bilateral asymmetry is reduced by bilateral current exchange. Compared with the traditional low-offset vertical Hall sensor with electrodes, the inter-interconnected seven-electrode low-offset vertical Hall sensor has the advantages that the offset voltage is reduced to 9.8% of the original offset voltage, and the offset magnetic field is reduced to 11.7% of the original offset voltage.)

1. An internal interconnection seven-electrode low-offset vertical Hall magnetic sensor is characterized by comprising:

the active region is used as an electronic motion space and generates Hall voltage by combining Hall effect, thereby realizing the detection of a magnetic field;

an electrode: connecting the active region with an external circuit for applying constant current excitation and outputting Hall voltage; wherein, the number of the electrodes is 7, and the electrodes are respectively C1-C7 and are distributed symmetrically;

interconnection lines: the internal interconnection of the chip is realized by adopting two metal layers of M1 and M2; the electrodes C2 and C6 are interconnected through a metal layer M1 and grounded through a metal layer M1 pin PAD 0; the electrode C1 and the electrode C5 are interconnected through a metal layer M1, and Hall voltage output is realized through a metal layer M1 pin PAD 1;

the electrode C4 realizes bias current input through a metal layer M2 pin PAD 3; electrode C3 is interconnected with C7 by metal layer M2 and the hall voltage output is achieved through metal layer M2 pin PAD 2.

2. The interconnected seven-electrode low offset vertical hall magnetic sensor of claim 1 wherein the active region is of a narrow strip design with a length and width of 90 μm and 3 μm.

3. The interconnected seven-electrode low offset vertical hall magnetic sensor of claim 1 wherein the width of the electrodes is 1 μm.

4. The inner-interconnected seven-electrode low-offset vertical Hall magnetic sensor according to claim 1 or 3, wherein the distance between the electrodes C1 and C2 is 13 μm, the distance between the electrodes C2 and C3 is 11 μm, the distance between the electrodes C3 and C4 is 13 μm, the distance between the electrodes C4 and C5 is 13 μm, the distance between the electrodes C5 and C6 is 11 μm, and the distance between the electrodes C6 and C7 is 13 μm.

5. The interconnected seven-electrode low-offset vertical Hall magnetic sensor according to claim 2, wherein the active region has a doping concentration no higher than E18cm^-3And the depth of the N-type doped region is not less than 1 mu m.

6. The interconnected seven-electrode low offset vertical Hall magnetic sensor of claim 1, wherein the metal layers M1 and M2 are connected with the electrodes by means of through holes.

Technical Field

The invention relates to a vertical Hall magnetic sensor, in particular to an internal interconnection seven-electrode low-offset vertical Hall magnetic sensor.

Background

The CMOS integrated Hall magnetic field sensor is widely applied to the fields of industrial control, intelligent instruments and meters, consumer electronics and the like, the three-dimensional Hall magnetic sensor is used as an extension of a single-axis Hall magnetic sensor, has wider application scenes and higher precision, and the vertical Hall magnetic sensor can be used for detecting a magnetic field parallel to the surface of the sensor and is an indispensable part of the three-dimensional Hall sensor. However, the offset voltage, as an output voltage in the absence of a magnetic field, seriously affects the performance and long-term stability of the CMOS vertical hall device.

The conventional vertical hall device employs a five-electrode structure as shown in fig. 1. The active region adopts an N-type doped region and is connected with an external circuit through 5 electrodes, wherein constant current bias is applied among C1, C3 and C5, and Hall voltage is induced between C2 and C4 so as to obtain a magnetic field. In the ideal case, when the magnetic field is 0, there is no voltage difference between C2 and C4 due to the symmetry of the structure. But asymmetry can be introduced due to mask misalignment, package pressure, etc., resulting in misalignment. Therefore, in the presence of a magnetic field, the voltage V between C2 and C4_C2-C4The device comprises two parts: hall voltage V_HallAnd offset voltage V_offIt can be expressed as:

V_C2-C4＝V_Hall+V_off(1)。

the current-dependent sensitivity S of the Hall sensor can be obtained by means of the Hall voltage_I：

Wherein, I_inAnd B represent applied bias current and magnetic field, respectively. The offset magnetic field B can be obtained by the offset voltage and the current-dependent sensitivity_off：

The small offset magnetic field can effectively improve the resolution and the precision of the magnetic sensor. The conventional five-electrode vertical Hall magnetic sensor has larger offset voltage and offset magnetic field, cannot meet the requirements of engineering application, and greatly hinders the research and development of the CMOS three-dimensional Hall magnetic sensor.

Disclosure of Invention

The invention aims to solve the technical problem of providing a low-offset vertical Hall magnetic sensor aiming at the defects of the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an inter-connected seven-electrode low-offset vertical hall magnetic sensor, comprising:

the active region is used as an electronic motion space and generates Hall voltage by combining Hall effect, thereby realizing the detection of a magnetic field;

an electrode: connecting the active region with an external circuit for applying constant current excitation and outputting Hall voltage; wherein, the number of the electrodes is 7, and the electrodes are respectively C1-C7 and are distributed symmetrically;

interconnection lines: the internal interconnection of the chip is realized by adopting two metal layers of M1 and M2; the electrodes C2 and C6 are interconnected through a metal layer M1 and grounded through a metal layer M1 pin PAD 0; the electrode C1 and the electrode C5 are interconnected through a metal layer M1, and Hall voltage output is realized through a metal layer M1 pin PAD 1;

the electrode C4 realizes bias current input through a metal layer M2 pin PAD 3; electrode C3 is interconnected with C7 by metal layer M2 and the hall voltage output is achieved through metal layer M2 pin PAD 2.

The electrode electrodes C1 and C5, and C3 and C7 are interconnected to balance the asymmetry of the left and right ends to reduce the offset.

Specifically, the active region is designed by narrow strips, the length and the width of the active region are divided into 90 μm and 3 μm, and the current-dependent sensitivity of the magnetic sensor can be improved as much as possible while the process precision is ensured.

Preferably, the width of the electrode is 1 μm, so that the influence of the short-circuit effect on the current-dependent sensitivity is reduced while the process precision is ensured.

Preferably, the distance between electrodes C1 and C2 is 13 μm, the distance between electrodes C2 and C3 is 11 μm, the distance between electrodes C3 and C4 is 13 μm, the distance between electrodes C4 and C5 is 13 μm, the distance between electrodes C5 and C6 is 11 μm, and the distance between electrodes C6 and C7 is 13 μm, in order to reduce initial misalignment.

Preferably, the doping concentration of the active region is not higher than that of E18cm^-3And the depth of the N-type doped region is not less than 1 mu m.

Preferably, the interconnection line is designed by adopting a double-layer metal layer, the phenomenon of crossing of the interconnection between the detection electrodes exists, the double-layer design can be adopted to separate the design so as to reduce the line length and reduce the external interference, and the metal layers M1 and M2 are connected with the electrodes by adopting a through hole mode.

Has the advantages that:

compared with the traditional low-offset vertical Hall sensor with electrodes, the inter-interconnected seven-electrode low-offset vertical Hall sensor has the advantages that the offset voltage is reduced to 9.8% of the original offset voltage, and the offset magnetic field is reduced to 11.7% of the original offset voltage.

Drawings

The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

Fig. 1 is a three-dimensional diagram of a conventional five-electrode vertical hall magnetic sensor.

FIG. 2 is a slope diagram of a vertical Hall magnetic sensor with seven interconnected electrodes and the interconnection mode.

Fig. 3 is a two-dimensional simulation through COMSOL, in which gray-scale colors represent the voltage distribution on the surface of the device.

Detailed Description

The invention will be better understood from the following examples.

The structures, proportions, and dimensions shown in the drawings and described in the specification are for understanding and reading the present disclosure, and are not intended to limit the scope of the present disclosure, which is defined in the claims, and are not essential to the skilled in the art. In addition, the terms "upper", "lower", "front", "rear" and "middle" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the relative positions may be changed or adjusted without substantial technical changes.

Conventional pendantThe straight hall device adopts a five-electrode structure as shown in fig. 1. In the absence of a magnetic field, the voltage between the electrodes C2 and C4 is referred to as an offset voltage, and the voltage difference between C2 and C4 is caused by the asymmetry across the electrode C3, so it is considered that two more electrodes are added across C3, and then the asymmetry across C3 is balanced by the interconnection between the electrodes, thereby reducing the offset voltage between C2 and C4. In view of the above, a vertical Hall magnetic sensor with seven interconnected electrodes as in FIG. 2 is obtained, the present invention is based on 0.18 μm BCDlite from GLOBALFOUNDRIES^TMThe process parameters are verified and researched, and the advantages of the structure have universality for other process parameters.

As shown in FIG. 2, the N-type doping is used for the active region, and for the vertical Hall sensor, the lower the doping concentration and the deeper the depth of the active region are, the more beneficial the sensor performance is, and for GLOBALFOUNDRIES, 0.18 μm BCDlite^TMThe process selects the doping concentration of 1.84E 17cm^-3And a region with a depth of 1.018 μm.

The electrodes are implemented using heavily doped N regions to reduce the contact resistance between the interconnect lines and the active region. The connection of the 7 electrodes is shown in fig. 2a, with a symmetrical distribution. Fig. 2b and fig. 2c show the way of realizing the internal interconnection of the chip by using two metal layers of M1 and M2. The electrodes C2 and C6 are interconnected through a metal layer M1 and grounded through a metal layer M1 pin PAD 0; the electrode C1 and the electrode C5 are interconnected through a metal layer M1, and Hall voltage output is realized through a metal layer M1 pin PAD 1; the electrode C4 realizes bias current input through a metal layer M2 pin PAD 3; the electrode C3 and the electrode C7 are interconnected through a metal layer M2, and Hall voltage output is realized through a metal layer M2 pin PAD 2; the metal layers M1 and M2 are connected with the electrodes in a through hole mode.

Bias current I_inIs divided into two paths after passing through C4, when the current respectively flows from the left side and the right side to pass through C3 and C5, a part of the current flows to C7 and C1 through the internal interconnection line, and is I_l1And I_r1These two partial currents can be used to balance the asymmetry across electrode C4 to reduce misalignment, although current I_l1And I_r1Also reduces the effective current at the detection electrode, resulting in a current dependent sensitivity S_IReduction ofBut generally for offset magnetic field B_offIn other words, the structure greatly improves the precision and the resolution of the vertical Hall sensor.

In order to verify the advantages of the present invention, a COMSOL finite element analysis software is adopted for verification, a two-dimensional model and circuit connection of a device are established in the software, the model in the COMSOL is shown in fig. 3, gray color represents the voltage distribution on the surface of the sensor, and the asymmetry of the voltage on two sides of the electrode C4 can be seen from the voltage distribution, because the device is placed in a 1T magnetic field B, and the existence of the magnetic field can bring hall effect, which can bring the asymmetry of the voltage on two sides of the electrode C4, namely, the voltage difference between the electrodes C3 and C5, namely, the hall voltage V is formed_Hall. Bias current I in simulation_inIs 1 mA. According to Hall voltage V_HallBias current I_inAnd the magnetic field B can be calculated by the formula (2) to obtain the current-dependent sensitivity S_I. To introduce offset, we reduced the size of electrode C6 by 0.01 μm in the simulation model, and the voltage difference between electrodes C3 and C5 is the offset voltage V when no magnetic field exists_offThe detuned magnetic field B can be obtained by the formula (3)_off. In order to compare the advantages of the seven-electrode vertical hall sensor, compared with the five-electrode vertical hall device with the same size, the five-electrode vertical hall magnetic sensor with the corresponding size can be obtained by only connecting the electrodes C1 and C7 in fig. 2 without a circuit.

Table 1: the performance of the internal interconnection seven-electrode low-offset vertical Hall magnetic sensor with the same size is compared with that of a traditional five-electrode Hall sensor.

As can be seen from the above table, the inter-connected 7-electrode low-offset vertical Hall magnetic sensor has a current dependent sensitivity S in comparison with the conventional 5-electrode Hall sensor_IAlthough the reduction is 16.2%, the offset voltage and the offset magnetic field are respectively reduced to 9.8% and 11.7% of those of the traditional five-electrode sensor, and the improvement can effectively improve the accuracy and the resolution of the sensor.

The present invention provides a concept and a method for an inter-connected seven-electrode low-offset vertical hall magnetic sensor, and a method and a way for implementing the technical solution are many, and the above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and embellishments can be made without departing from the principle of the present invention, and these improvements and embellishments should also be regarded as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.