TGV integrated fluxgate chip

Abstract

The TGV integrated fluxgate chip comprises a first glass substrate (1), a second glass substrate (11), an excitation coil (2), a detection coil (3), a magnetic core (4) and an electrode (5), a rectangular groove and a microgroove array are respectively distributed on the upper surface and the lower surface of the first glass substrate (1), and a microgroove array is distributed on the lower surface of the second glass substrate (11); the excitation coil (2) and the detection coil (3) are micro-electro-mechanical three-dimensional solenoid conductive coils, and the TGV integrated fluxgate chip achieves input and output of signals through the electrode (5). According to the invention, a method of combining an MEMS technology and a TGV method is adopted, the integration of using a glass material as a substrate and insulating is realized, the chip is very light and thin, is particularly useful for applications requiring weight and space sensitivity, and effectively solves the problem that the existing MEMS fluxgate sensor chip cannot bear repeated mechanical stress and deformation.

Description

Technical Field

[0001] This invention mainly relates to the field of chips, and in particular to a TGV integrated fluxgate chip. Background Technology

[0002] Fluxgate sensors, as a traditional weak magnetic field detection device, have always possessed unique advantages that make them irreplaceable by other magnetic field sensors. In recent years, they have continuously discovered their application potential in new fields, such as current detection, indoor geomagnetic positioning, missile inertial guidance, small satellite attitude control, virtual reality motion detection, and intelligent transportation. In recent years, due to the gradual expansion of applications in various fields, the requirements for devices have become increasingly demanding—thinner, lighter, and cheaper. Correspondingly, fluxgate sensors are also striving to become thinner, lighter, and cheaper.

[0003] Traditional fluxgate magnetometers use a robust frame as a base, with a soft magnetic core fixed to it. An excitation coil that generates a magnetic field by passing an electric current is then wound around the frame, along with a magnetic field induction coil that detects the effects of an external magnetic field based on the magnetic field induced by the excitation coil. This limits the operating temperature range of traditional fluxgate magnetometers, and they are also large, heavy, have low sensitivity, and poor long-term stability. The development of MEMS technology provides an effective and reliable approach for the development of miniaturized fluxgate magnetometers. Compared to traditional fluxgate magnetometer probes, MEMS fluxgate magnetometer probes are compact, small in size and weight, easy to install and debug, resistant to vibration and impact, and less affected by changes in ambient temperature. The development of TGV integrated fluxgate magnetometers using MEMS technology has become a hot research topic both domestically and internationally.

[0004] A literature search of existing technologies revealed that J. Kubik et al. (L. Pavel and P. Ripka) published a paper titled "Low-Power Printed Circuit Board Fluxgate Sensor" in *IEEE Sensor Journal*, Vol. 7, pp. 179-183, 2007. This paper describes a miniature fluxgate sensor developed using multilayer printed circuit board technology. The magnetic core has a rectangular structure and is made of a 25-micrometer-thick Vitrovac 6025 X amorphous alloy strip. At 10 kHz, the fluxgate sensor has a sensitivity of 94 V / T and a power consumption of only 3.9 mW. However, because the fabrication process requires drilling through-holes to wind the coil on the magnetic core, the sensor may be damaged during the through-hole process, and the printed circuit board cannot withstand high-temperature environments. Furthermore, compared to MEMS technology, it is difficult to improve the performance of the fluxgate sensor using this method. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention includes: How to design a TGV integrated fluxgate chip, manufactured using MEMS technology, and characterized by low cost, small size, light weight, high temperature resistance, and shock resistance.

[0006] To achieve the above objectives, the present invention provides a TGV integrated fluxgate chip, comprising: a first glass substrate, a second glass substrate, an excitation coil and a detection coil, a magnetic core, and electrodes; rectangular grooves and microgroove arrays are respectively distributed on the upper and lower surfaces of the first glass substrate, and a microgroove array is distributed on the lower surface of the second glass substrate; the excitation coil and the detection coil are microelectromechanical three-dimensional solenoid conductive coils; the excitation coil and the detection coil include a bottom coil and a top coil, the bottom coil being disposed within the microgroove array on the lower surface of the first glass substrate; the top coil being disposed within the microgroove array on the lower surface of the second glass substrate; the copper conductive wires of the bottom coil and the top coil are insulated by a glass dielectric between the gaps in the microgroove array; the magnetic core is disposed within a rectangular groove on the upper surface of the first glass substrate, the rectangular groove being deep... The thickness of the magnetic core is greater than that of the magnetic core to prevent the magnetic core from contacting the top layer coil. A copper connecting conductor array is provided on both sides of the magnetic core on the first glass substrate, and the copper connecting conductor array is exposed on the upper surface of the first glass substrate. The copper connecting conductor array is connected to the two ends of the corresponding bottom layer coil on the lower surface of the first glass substrate to achieve electrical conduction. The copper connecting conductor array is connected to the two ends of the copper conductive wire of the top layer coil by low-temperature electro-copper direct bonding to form a complete microelectromechanical three-dimensional solenoid conductive coil. The electrode is disposed on the upper surface of the second glass substrate and is connected to the input and output terminals of the microelectromechanical three-dimensional solenoid conductive coil through a copper connecting conductor penetrating the second glass substrate to achieve electrical conduction. The TGV integrated fluxgate chip realizes signal input and output through the electrodes.

[0007] Furthermore, the microgroove array is formed on the surfaces of the first and second glass substrates using a dry etching process, and the width, depth, and length of the microgroove array are equal to the width, thickness, and length of the energized wires of the bottom coil and the top coil.

[0008] Furthermore, the dry etching process is an inductively coupled plasma dry etching process.

[0009] Furthermore, the magnetic core is an electroplated permalloy with a thickness of 20 μm.

[0010] Furthermore, the rectangular groove has the same length and width as the magnetic core, and the depth of the rectangular groove is 30 μm.

[0011] Furthermore, the copper connecting conductor array is located on both sides of the magnetic core in the horizontal direction and is symmetrically 10 μm higher than the upper surface of the magnetic core in the thickness direction. The spacing between two adjacent columns of the copper connecting conductor array is equal to the length of the energized wires of the bottom coil and the top coil. The spacing between the copper connecting conductor array and the magnetic core is 100 μm. The height of the copper connecting conductor is equal to the thickness of the first glass substrate. The width and gap of the copper connecting conductor are both 50 μm.

[0012] Furthermore, the copper connecting conductor is realized using the TGV process, which involves creating micro-vias on a glass substrate using a pulsed laser and filling the micro-vias with electroplated copper to obtain the TGV copper connecting conductor.

[0013] Furthermore, the materials of the excitation coil and the detection coil are electroplated copper.

[0014] Furthermore, the electrode is made of electroformed copper.

[0015] Furthermore, the low-temperature electrochemical copper-copper direct bonding connection is achieved using a low-temperature electrochemical copper-copper bonding process at 100°C.

[0016] Compared with existing technical solutions, the technical advantages of the present invention are as follows: This invention combines MEMS technology with the TGV method to achieve integrated insulation using glass as a substrate. This results in a lightweight and thin design, which is particularly useful for applications requiring weight and space sensitivity, such as wearable and mobile devices. It can be attached to or integrated into surfaces, which is crucial for monitoring minute changes and responding quickly to environmental changes. It effectively solves the problem that existing MEMS fluxgate sensor chips cannot withstand repeated mechanical stress and deformation, which is especially important when dealing with physical impacts during daily wear and use.

[0017] This invention uses glass as the substrate and as insulation, support, and coating materials, which can adapt to various special environmental application requirements, such as wearable devices and mobile devices, thus expanding the application range of TGV integrated fluxgate chips and enhancing their competitiveness.

[0018] This invention employs a low-temperature hot-pressing copper-copper bonding process to connect energized wires to form a complete TGV integrated fluxgate chip. The structure is compact, the manufacturing method is fast and simple, the manufacturing cycle is short, and the production cost is significantly reduced, effectively promoting the large-scale and widespread application of TGV integrated fluxgate sensors.

[0019] This invention uses MEMS technology to develop a TGV integrated fluxgate chip, which has better stability, higher repeatability, simpler installation and debugging process, is more robust, and is less affected by changes in ambient temperature and external stress compared with traditional fluxgate sensors. This invention is developed using MEMS technology, which can directly realize a two-axis miniature fluxgate sensor and fluxgate sensor array based on this invention. At the same time, the process is fully compatible with large-scale integrated circuit technology and can be directly integrated with interface circuits for manufacturing, thereby providing more magnetic measurement functions to meet the needs of different application fields, such as indoor geomagnetic positioning, missile inertial guidance, small satellite attitude control, virtual reality motion detection, intelligent transportation, etc. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the microstructure of the bottom coil core on a glass substrate according to a preferred embodiment of the present invention; Figure 2 This is a schematic diagram of the microstructure of the top coil on the glass substrate according to a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a TGV integrated fluxgate chip according to a preferred embodiment of the present invention; Figure 4 It is along Figure 3 The cross-sectional view of line AA shown.

[0021] Figure Labels

[0022] 1-First glass substrate, 11-Second glass substrate, 2-Excitation coil, 3-Detection coil, 4-Magnetic core, 5-Electrode, 6-Bottom layer coil, 7-Top layer coil, 8-Copper connecting conductor array, 9-Copper connecting conductor. Detailed Implementation

[0023] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0024] like Figures 1-4As shown, a TGV integrated fluxgate chip includes a first glass substrate 1, a second glass substrate 11, an excitation coil 2 and a detection coil 3, a magnetic core 4, and an electrode 5. The upper and lower surfaces of the first glass substrate 1 are respectively distributed with rectangular grooves and a microgroove array, and the lower surface of the second glass substrate 11 is distributed with a microgroove array. The excitation coil 2 and the detection coil 3 are microelectromechanical three-dimensional solenoid conductive coils. The excitation coil 2 and the detection coil 3 include a bottom coil 6 and a top coil 7. The bottom coil 6 is disposed within the microgroove array on the lower surface of the first glass substrate 1; the top coil 7 is disposed within the microgroove array on the lower surface of the second glass substrate 11. The copper conductive wires of the bottom coil 6 and the top coil 7 are insulated by a glass dielectric between the gaps in the microgroove array. The magnetic core 4 is disposed within a rectangular groove on the upper surface of the first glass substrate 1, the depth of which is greater than [missing information]. The thickness of the magnetic core 4 is such that it prevents contact between the magnetic core 4 and the top layer coil 7. The first glass substrate 1 has a copper connecting conductor array 8 on both sides of the magnetic core 4, and the copper connecting conductor array 8 is exposed on the upper surface of the first glass substrate 1. The copper connecting conductor array 8 is connected to the two ends of the corresponding bottom layer coil 6 on the lower surface of the first glass substrate 1 to achieve electrical conduction. The copper connecting conductor array 8 is connected to the two ends of the copper current-carrying wire of the top layer coil 7 by low-temperature electro-copper direct bonding to form a complete microelectromechanical three-dimensional solenoid conductive coil. The electrode 5 is disposed on the upper surface of the second glass substrate 11 and is connected to the input and output terminals of the microelectromechanical three-dimensional solenoid conductive coil through the copper connecting conductor 9 penetrating the second glass substrate 11 to achieve electrical conduction. The TGV integrated fluxgate chip realizes signal input and output through the electrode 5.

[0025] The microgroove array is formed by etching the surfaces of the first glass substrate 1 and the second glass substrate 11 using a dry etching process. The width, depth, and length of the microgroove array are equal to the width, thickness, and length of the energized wires of the bottom coil 6 and the top coil 7.

[0026] The dry etching process is an inductively coupled plasma dry etching process.

[0027] The magnetic core 4 is made of electroplated permalloy and has a thickness of 20 μm.

[0028] The rectangular groove has the same length and width as the magnetic core 4, and the depth of the rectangular groove is 30μm.

[0029] The copper connecting conductor array 8 is located on both sides of the magnetic core 4 in the horizontal direction and is symmetrically 10 μm higher than the upper surface of the magnetic core in the thickness direction. The spacing between two adjacent columns of the copper connecting conductor array 8 is equal to the length of the energized wires of the bottom coil 6 and the top coil 7. The spacing between the copper connecting conductor array 8 and the magnetic core 4 is 100 μm. The height of the copper connecting conductor 9 is equal to the thickness of the first glass substrate 1. The width and gap of the copper connecting conductor 9 are both 50 μm.

[0030] The copper connecting conductor 9 is achieved using the TGV process, which involves creating micro-vias on a glass substrate using a pulsed laser and filling the micro-vias with electroplated copper to obtain the TGV copper connecting conductor.

[0031] The excitation coil 2 and the detection coil 3 are made of electroplated copper.

[0032] The electrode 5 is made of electroformed copper.

[0033] The low-temperature electrochemical copper-copper direct bonding connection is achieved using a low-temperature electrochemical copper-copper bonding process at 100°C.

[0034] The first glass substrate 1 is 40 μm thick and 600 μm wide.

[0035] The surface of the first glass substrate 1 is distributed with a copper interconnect conductor array 8 having a length of 1000μm, a width of 50μm, and a depth of 20μm.

[0036] The copper conductive wires of the bottom coil 6 are insulated from each other by a 50μm wide glass dielectric between the gaps of the copper connecting conductor array 8. The upper surface of the bottom coil 6 is flush with the surface of the first glass substrate 1.

[0037] The copper conductive wires of the top coil 7 are insulated from each other by a 50μm wide glass dielectric between the gaps in the copper connecting conductor array 8. The upper surface of the top coil 7 is flush with the surface of the first glass substrate 1. The fluxgate current sensing chip exposes the electrode 5 through a 20μm deep through-hole.

[0038] During operation, a sinusoidal alternating current is applied to the excitation coil 2 to saturate the magnetic core 4. Without an external magnetic field, the detection coil 3 outputs no signal due to the differential effect; however, when an external magnetic field is present, the detection coil 3 will output a signal, which is an even-order harmonic. After filtering, a second-harmonic signal can be obtained. The magnitude of the second-harmonic signal is proportional to the external magnetic field. Therefore, the magnitude and direction of the external magnetic field can be measured.

[0039] In this embodiment, the copper connecting conductor 8 array is formed by dry etching at the bottom of a rectangular groove, with a width and gap of 50μm and a depth of 20μm.

[0040] In this embodiment, the copper connecting conductor 9 is formed by electroplating copper through a glass substrate. The height of the connecting conductor is 100μm, and the width and length are both 50μm.

[0041] In this embodiment, the magnetic core 4 is a rectangular electroplated permalloy magnetic core with a width of 1mm.

[0042] In this embodiment, both the excitation coil 2 and the detection coil 3 are microelectromechanical three-dimensional solenoid coil structures. This three-dimensional solenoid coil structure is formed by directly connecting the top coil 6 and the bottom coil 7 through through-holes in the surface of a silicon carbide substrate at both ends of a current-carrying conductor. The material of the three-dimensional solenoid coil is electroformed copper, and the linewidth of each turn of the conductor in the three-dimensional solenoid coil is 50 μm, the thickness is 20 μm, and the gap between each turn is 50 μm. The excitation coil has 60 turns, and the detection coil has 60 turns.

[0043] The TGV integrated fluxgate chip described in this embodiment is a planar fluxgate sensor based on MEMS technology, capable of accurately detecting magnetic fields. This invention employs a racetrack-shaped rectangular fluxgate structure design, with both the excitation and detection coils wound on the long axis of a magnetic core. The magnetic core is made of electroplated permalloy. The sensor features easy mass production, low cost, high sensitivity, low noise, and low power consumption. Specifically, a complete TGV integrated fluxgate chip is formed by directly bonding a glass substrate and using a low-temperature hot-pressing copper-copper bonding process to connect the conductive wires. This results in a compact structure, rapid and simple manufacturing, and a short manufacturing cycle, significantly reducing production costs and effectively promoting the large-scale and widespread application of TGV integrated fluxgate chips. Furthermore, it addresses the problems of poor compatibility with microelectronic processes, severe process contamination, low yield, and high cost, improving production efficiency, reducing noise and power consumption of the fluxgate sensor chip, and increasing signal response speed.

[0044] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0045] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A TGV integrated fluxgate chip, characterized in that: The system includes a first glass substrate (1), a second glass substrate (11), an excitation coil (2), a detection coil (3), a magnetic core (4), and an electrode (5). The first glass substrate (1) has rectangular grooves and a microgroove array distributed on its upper and lower surfaces, respectively, while the second glass substrate (11) has a microgroove array distributed on its lower surface. The excitation coil (2) and the detection coil (3) are microelectromechanical three-dimensional solenoid conductive coils. The excitation coil (2) and the detection coil (3) include a bottom coil (6) and a top coil (7). The bottom coil (6) is disposed within the microgroove array on the lower surface of the first glass substrate (1). The top coil (7) is disposed within the microgroove array on the lower surface of the second glass substrate (11). The copper conductive wires of the bottom coil (6) and the top coil (7) are insulated from each other by a glass dielectric between the gaps in the microgroove array. The magnetic core (4) is disposed within a rectangular groove on the upper surface of the first glass substrate (1), the depth of which is greater than the depth of the magnetic core (5). The thickness of the core (4) is such that the core (4) does not contact the top coil (7); the first glass substrate (1) has a copper connecting conductor array (8) on both sides of the core (4), and the copper connecting conductor array (8) is exposed on the upper surface of the first glass substrate (1); the copper connecting conductor array (8) is connected to the two ends of the corresponding bottom coil (6) on the lower surface of the first glass substrate (1) to achieve electrical conduction, and the copper connecting conductor array (8) is connected by low-temperature electro-copper-copper direct bonding between the two ends of the copper current-carrying wire of the top coil (7) to form a complete microelectromechanical three-dimensional solenoid conductive coil; the electrode (5) is set on the upper surface of the second glass substrate (11), and is connected to the input and output ends of the microelectromechanical three-dimensional solenoid conductive coil through the copper connecting conductor (9) penetrating the second glass substrate (11) to achieve electrical conduction; the TGV integrated fluxgate chip realizes signal input and output through the electrode (5).

2. The TGV integrated fluxgate chip according to claim 1, characterized in that: The microgroove array is formed by etching the surfaces of the first glass substrate (1) and the second glass substrate (11) using a dry etching process. The width, depth and length of the microgroove array are equal to the width, thickness and length of the energized wires of the bottom coil (6) and the top coil (7).

3. The TGV integrated fluxgate chip according to claim 2, characterized in that: The dry etching process is an inductively coupled plasma dry etching process.

4. The TGV integrated fluxgate chip according to claim 1, characterized in that: The magnetic core (4) is an electroplated permalloy with a thickness of 20 μm.

5. The TGV integrated fluxgate chip according to claim 1, characterized in that: The rectangular groove has the same length and width as the magnetic core (4), and the depth of the rectangular groove is 30 μm.

6. The TGV integrated fluxgate chip according to claim 2, characterized in that: The copper connecting conductor array (8) is located on both sides of the magnetic core (4) in the horizontal direction and is symmetrically 10 μm higher than the upper surface of the magnetic core in the thickness direction. The spacing between two adjacent columns of the copper connecting conductor array (8) is equal to the length of the current-carrying wires of the bottom coil (6) and the top coil (7). The spacing between the copper connecting conductor array (8) and the magnetic core (4) is 100 μm. The height of the copper connecting conductor (9) is equal to the thickness of the first glass substrate. The width and gap of the copper connecting conductor (9) are both 50 μm.

7. The TGV integrated fluxgate chip according to claim 6, characterized in that: The copper connecting conductor (9) is achieved using the TGV process. Micro-vias are created on a glass substrate using a pulsed laser, and then electroplated copper is used to fill the micro-vias to obtain the TGV copper connecting conductor.

8. The TGV integrated fluxgate chip according to claim 1, characterized in that: The excitation coil (2) and the detection coil (3) are made of electroplated copper.

9. The TGV integrated fluxgate chip according to claim 1, characterized in that: The electrode (5) is made of electroformed copper.

10. The TGV integrated fluxgate chip according to claim 9, characterized in that: The low-temperature electrochemical copper-copper direct bonding connection is achieved using a low-temperature electrochemical copper-copper bonding process at 100°C.

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