Finger type Hall sensor

Abstract

The invention discloses a finger type Hall sensor, and relates to the field of microelectronics and solid state electronics, in particular to a Hall sensor. A traditional cross-shaped Hall element is modified into a structure comprising four or more fingers, so that the influence of a multi-contact structure on current flowing in equipment is optimized, more current flows in an effective vector direction, and weakening of device geometric factors on sensitivity is reduced. A three-dimensional COMSOL model is used for simulating and comparing a current flow schematic diagram and current related sensitivity of a Hall device under the condition that a gap is 1-3 microns, and a Hall sensor with relatively high sensitivity is provided. The Hall device is characterized in that the Hall device is of a 90-degree rotationally symmetrical finger-shaped structure, the up-down width and the left-right width of the sensor size are 40 microns, the thickness of the sensor size is 5 microns, an active region adopts a silicon material 2.6 E + 16 cm < 3 > N well doped CMOS process, and when the gap width is 1.2 microns, the optimal 308.55 V / (AT) current related sensitivity can be obtained; compared with a traditional Hall piece model, the sensitivity is improved.

Description

Technical Field

[0001] The present invention relates to the fields of microelectronics and solid-state electronics, and particularly to Hall sensors. Background Art

[0002] With the further expansion of the global market scale of magnetic sensors, the domestic demand for various sensors is also increasing. High precision and high sensitivity have become new requirements for the research and development of Hall sensors. In order to improve the measurement accuracy and stability and reduce the alignment error of the sensor, today's Hall devices also include interface circuits for automatic zeroing, chopper stabilization (CHS), and correlated double sampling (CDS). At the same time, to adapt to these modules, the Hall device is designed in a cross shape with rotational symmetry, such as the design in the literature. However, through testing, it is found that the current inside the cross-shaped device changes and deflects during operation, resulting in a decrease in sensitivity. This is caused by the geometric shape of the device and the Hall contacts. The contact poles of the cross-shaped device provide a conductor, and the attractive current tends to flow along the path with the lowest resistance, which leads to a change in some current paths, generating an ineffective vector current and reducing the measured value of the current, ultimately resulting in a decrease in the sensitivity of the device. Literature [Fan, H. Yue, E. Bonizzoni, Q. Feng and Q. Wei, "Modeling of Three-Axis Hall Effect Sensor Based on CMOS Process," in IEEE Sensors Journal, vol. 23, no. 20, pp. 24686 - 24695, 15 Oct. 15, 2023, doi: 10.1109 / JSEN.2023.3312598.] Summary of the Invention

[0003] The technical solution of the present invention is a finger-shaped current Hall element that uses structural design to optimize the geometric factor of the Hall device, mainly to reduce the influence of the device geometry on device performance such as sensitivity. Based on the fact that current always tends to choose the path with the lowest resistance, the finger-shaped Hall device increases the resistance on the ineffective current path and has almost no influence on the effective current path, enabling the current to concentrate on the effective path. This shape greatly reduces the path change and deflection of the current in the device and improves the sensitivity of the device.

[0004] The technical solution of the present invention is a finger-shaped Hall sensor. The Hall sensor has an overall rotationally symmetric sheet structure, including an N-well and contact poles. The N-well includes a body and fingers. When viewed from above, the body is a square structure, and more than 2 fingers extend outward from the four sides of the square structure. Contact poles are arranged at the top of the fingers.

[0005] Further, the body is a cuboid with a length of 22 microns, a width of 22 microns, and a height of 1.5 microns; 4 fingers extend outward from each side, each finger has a size of 9 microns in length, 4 microns in width, and 1.5 microns in height, and the spacing between fingers is 2 microns.

[0006] Further, the material of the N-well is N-type doped silicon semiconductor, its electron mobility is 1252 cm² / V·s, and the hole mobility is 407 cm² / V·s.

[0007] Further, the contact electrode is a cuboid with a length of 0.5 microns, a width of 0.5 microns, and a height of 0.17 microns. Each contact electrode is precisely embedded on the central axis of the top of each finger and is close to the edge.

[0008] By modifying the traditional cross-shaped Hall element into a structure containing four or more fingers, the influence of the multi-contact structure on the current flow in the device is optimized, enabling more current to flow in the effective vector direction, thereby reducing the weakening of the device geometric factor on the sensitivity; compared with the traditional Hall sensor, the sensitivity of the present invention is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic geometric diagram of the Comsol model of the present invention.

[0010] Figure 2 It is the curve relationship between the gap width and the current-related sensitivity obtained by simulating with the Comsol model.

[0011] Figure 3 It is a schematic diagram of the current flow of the conventional cross Hall device model.

[0012] Figure 4 It is a schematic diagram of the current flow of the finger-type Hall device model. DETAILED DESCRIPTION OF THE INVENTION

[0013] This Hall device is a precision semiconductor component with a three-dimensional structure, and its structure includes two layers of N-well and contact electrodes, as Figure 1 shown. The base of the N-well presents a rotationally symmetric structure, and the central part is a cuboid with a length of 22 microns, a width of 22 microns, and a height of 1.5 microns. Starting from this central cuboid, 4 long strip-shaped fingers are evenly distributed in four directions around. Each finger has a size of 9 microns in length, 4 microns in width, and 1.5 microns in height, and the spacing between fingers is 2 microns. The material constituting the N-well is N-type doped silicon semiconductor, its electron mobility is 1252 cm² / V·s, and the hole mobility is 407 cm² / V·s. These parameters together determine its anisotropic conductivity characteristics. After measurement, its anisotropic conductivity is as follows:

[0014]

[0015] The contact electrode consists of 16 cuboids with a length of 0.5 microns, a width of 0.5 microns, and a height of 0.17 microns. Each contact electrode is precisely embedded on the central axis of the top of each finger and is close to the edge. This layout ensures good electrical contact and mechanical stability between the contact electrode and the finger. The material forming the contact electrode is a more highly doped N-type doped silicon semiconductor. This high doping concentration can effectively reduce the contact resistance and improve the electrical performance of the device.

[0016] The studied Hall device is fabricated using integrated circuit technology, and its manufacturing process includes multiple complex steps. First, the patterns of the N-well and the contact electrode are defined on the silicon wafer through photolithography technology. Then, impurities are doped into the silicon wafer using ion implantation or diffusion processes to form an N-type doped region. Next, the doped region is planarized through processes such as chemical mechanical polishing to ensure the accuracy of subsequent processes. Finally, the contact electrode is formed on the top of the finger through metallization processes, completing the fabrication of the entire Hall device. This integrated circuit technology has the functions of enabling high-precision device fabrication and ensuring the performance stability and consistency of the device.

[0017] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0018] To obtain a sensor with higher sensitivity, the material properties of the N-well doping process with a higher mobility of 2.6E+16 cm-3 are selected for the Hall plate model. The Hall relationship shows that for a certain bias current I bias and magnetic field B z , the output Hall voltage V H of the Hall device is

[0019] where n is the carrier concentration, q and t respectively represent the charge of a carrier and the thickness of the semiconductor. The Hall factor r H represents the influence of the scattering effect on the Hall voltage; and the geometric factor G explains the non-ideality caused by the device geometry. In an ideal case, the device geometric factor G of a point Hall contact is 1. Based on this formula, the current-related sensitivity formula can also be deduced as Since the finger-type Hall device reduces the path change and deflection of the current in the device, it will have a larger geometric factor compared to the cross-type device, thereby obtaining a larger Hall voltage and current-related sensitivity.

[0020] The technology of the present invention is a method for establishing a cross-type current Hall element model based on COMSOL Multiphysics and Cadence Virtuoso. This method includes the following steps:

[0021] Step 1: Construct a 3D finger-shaped Hall plate model on the COMSOL Multiphysics platform;

[0022] Step 2: In COMSOL Multiphysics, select to construct a "3D" model. For the physical field, select the "Current" module in the "AC / DC" module, and then select the "Steady State" study;

[0023] Step 3: In the "Global Definitions" of COMSOL Multiphysics, add Hall plate size parameters, doping concentration parameters, magnetic field strength parameters, and material anisotropic conductivity parameters. Set the magnetic field to 0.05 T, the bias current to 2 mA, and the bias voltage to 5 V;

[0024] Step 4: Create "Component 1", add "Geometry 1" to start constructing the geometric model. Construct "Cuboid 1" and set its width, depth, and height to the defined parameters "length", "length", and "height" respectively, with the position centered; Set 4 cuboids with width, depth, and height of the defined parameters "cor", "cor", and "height" respectively, and set their positions at the four corners of "Cuboid 1" and perform a "subtraction" operation.

[0025] Step 5: At the trisection points on the four sides of the geometric model constructed in the previous step, construct three cuboids with width, depth, and height of the defined parameters "cor", "wgap",

[0026] "height" and perform a "subtraction" operation to construct the "finger" shape. Finally, add cuboids with width, depth, and height of "1", "1", and "hei" at the edges of each "finger" as contact poles, and finally perform a "form union" operation, as shown in the attachment Figure 1 as shown;

[0027] Step 6: Select materials. For the "finger"-shaped substrate, select the material "NWELL", and for the edge contact poles, select the material type "CONNECT";

[0028] Step 7: In the "ec" physical field of COMSOL Multiphysics, add "Terminal" boundary conditions. Add Hall plate current bias conditions of "I_bias" and "-I_bias" to the two opposite terminals respectively, and add "floating potential" boundaries to the other two opposite terminals, with the conditions that the current = 0 and the initial voltage = 0;

[0029] Step 8: Add a "parametric sweep" study in COMSOL Multiphysics to simulate different structures of the Hall plate with the gap length varying from 1 μm to 3 μm and calculate and compare the performance differences; by setting the probe output results of the current-related sensitivity formula, obtain the current-related sensitivity of the model, as shown in the appendix Figure 2 , and it is found that the best result can be obtained when the gap is 1.2 μm, with a current-related sensitivity of 308.55 V / (AT);

[0030] Step 9: Select the electric potential in the COMSOL Multiphysics simulation results and add an expression "Body Arrow 1" in it, which is set as:

[0031]

[0032] where Jx, Jy, and Jz represent the conduction current densities in the X, Y, and Z directions, and obtain the schematic diagram of the current flow in the model. As shown in the appendix Figure 3 is the schematic diagram of the current flow of the conventional cross Hall device model. The schematic diagram of the current flow of this model is as shown in the appendix Figure 4 , and comparing it with the appendix Figure 3 can clearly show the optimization of the current path by this structure.

[0033] Table 1 summarizes the voltage-related sensitivities of the corresponding Hall device models at different gap lengths. The range of the interdigital length variation is from 1 μm to 3 μm. The data in Table 1 show that when the interdigital length is 1.2 μm, a Hall voltage of 0.030855 V is obtained, corresponding to the best result with a current-related sensitivity of 308.55 V / (AT)

[0034] Table 2 summarizes the performance comparison between the traditional cross Hall model and the current Hall model proposed in the present invention. Table 2 shows that compared with the traditional magnetic field Hall plate model, the Hall model designed in the present invention optimizes the parameter settings and has better sensitivity performance.

[0035] Table 1 Relationship between magnetic field strength and current

[0036]

[0037] Table 2 Performance comparison between the traditional magnetic field Hall model and the current Hall model of the present invention

[0038] Traditional cross model Model proposed by the present invention Current path correction None Yes Hall plate model 3D model 3D model Hall plate structure 90° rotationally symmetric cross 90° rotationally symmetric finger shape Voltage-related sensitivity 0.0652 V / (VT) 0.0836 V / (VT) Current-related sensitivity 277.2 V / (AT) 308.55 V / (AT)

Claims

1. A finger-type Hall sensor, which has a rotationally symmetrical sheet structure as a whole, including an N-well and a contact electrode. The N-well includes a body and a finger. The body is a square structure when viewed from above. The four sides of the square structure extend outward by more than two fingers, and a contact electrode is set at the top of the finger.

2. A finger-type Hall sensor as claimed in claim 1, characterized in that: The main body is a cuboid with a length of 22 microns, a width of 22 microns, and a height of 1.5 microns; 4 fingers extend outward from each side, each finger is 9 microns long, 4 microns wide, and 1.5 microns high, and the spacing between the fingers is 2 microns.

3. A finger-type Hall sensor as claimed in claim 2, characterized in that: The material of the N-well is an N-type doped silicon semiconductor, the electron mobility of which is 1252 square centimeters / volt-second, and the hole mobility of which is 407 square centimeters / volt-second.

4. A finger-type Hall sensor as claimed in claim 2, characterized in that: The contact pole is a cuboid with a length of 0.5 microns, a width of 0.5 microns and a height of 0.17 microns. Each contact pole is precisely embedded in the central axis of the top of each finger and close to the edge.

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