Fluxgate Chip Manufacturing via Silicon Wafer Bonding
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Solution Overview
Problem
Existing manufacturing methods for fluxgate sensors result in large, heavy, high-power consumption devices with low sensitivity and poor long-term stability, which cannot meet the requirements for microminiaturization in electronic devices. Additionally, these methods lead to thick chips and low efficiency in production.
Innovation Solution
A manufacturing method for a fluxgate chip involving electroplating a ferromagnetic core on one silicon wafer and etching a core cavity on another, followed by bonding, oxidation treatment, and etching to form coil grooves and electrode windows, ultimately filling an annular cavity with alloy to create the fluxgate chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If bonding is performed after etching in the manufacturing process, then the chip structure can accommodate the magnetic core, but the chip thickness becomes large
Solution Approach 1:
The patent applies preliminary action by performing the bonding of silicon wafers before etching the coil grooves and electrode windows. This sequence allows the magnetic core to be securely positioned between the wafers prior to subsequent processing steps, preventing core displacement and enabling thinner chip design while maintaining manufacturing feasibility
2Productivity
If manual insertion of magnetic core is used, then the magnetic core can be positioned in the cavity, but the production efficiency is low
Solution Approach 1:
The patent implements self-service by designing the magnetic core cavity with features that enable the magnetic core to be automatically positioned and secured during the wafer bonding process. The core is retained in the cavity through the bonding operation itself, eliminating the need for separate manual insertion steps and enabling automated high-volume production
3Volume of moving object
If traditional winding method is used for solenoid coil, then the coil can be formed on magnetic core, but the sensor size and weight become large
Solution Approach 1:
The patent replaces the traditional mechanical winding method with a semiconductor fabrication-based coil formation process. Coils are created using deposition and patterning techniques similar to standard IC manufacturing, enabling precise control of coil geometry and allowing significant miniaturization of the sensor while maintaining manufacturability through established semiconductor processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves a fluxgate chip with reduced thickness and increased strength, enabling large-scale batch production, improved working efficiency, and reduced production costs.
Implementation Method 1
electroplating a ferromagnetic core on a first surface of one of the two high-resistance silicon wafers
Implementation Method 2
performing oxidation treatment on a second surface of the high-resistance silicon wafer electroplated with the ferromagnetic core and a second surface of the high-resistance silicon wafer provided with the ferromagnetic core cavity to form insulating layers by deposition
Data Source
AI summary
A manufacturing method for a fluxgate chip, comprising: firstly, selecting two high-resistance silicon wafers, electroplating a ferromagnetic core on the surface of one of the two high-resistance silicon wafers, and providing a ferromagnetic core cavity on the surface of the other high-resistance silicon wafer; then, bonding the two high-resistance silicon wafers up and down; next, respectively providing coil grooves, through grooves and electrode windows on the surfaces of opposite sides of the two high-resistance silicon wafers to form a silicon wafer mold; and finally, filling the surface of the silicon wafer mold with alloy. By means of electroplating, post-bonding and final etching, on the one hand, the formed fluxgate chip has both small thickness and sufficient strength, on the other hand, large-scale batch production of the fluxgate chip can be achieved, the working efficiency is improved, and the production cost is reduced.