Inverted pyramid 3-axis silicon Hall-effect magnetic sensor with offset cancellation.

Area of Science:

• Microelectronic Engineering
• Solid-State Physics
• Sensor Technology

Background:

• Hall-effect devices dominate the magnetic sensor market due to their reliability, low cost, and CMOS compatibility.
• Existing 3-axis magnetic sensors can be complex and costly.
• There is a need for compact, high-performance 3-axis magnetic sensors.

Purpose of the Study:

• To introduce a novel 3-axis Hall-effect sensor element.
• To demonstrate its capability for detecting both in-plane and out-of-plane magnetic fields.
• To showcase significant offset reduction using the current-spinning method.

Main Methods:

• Utilizing MEMS micromachining and CMOS processing to create an inverted pyramid structure.
• Employing TMAH etching and n-dopant implantation to define the active sensor area.
• Implementing various bias-sense detection modes and the current-spinning method for offset reduction.

Main Results:

• The novel sensor effectively detects both in-plane and out-of-plane magnetic fields in a single structure.
• Offset reduction by one to three orders of magnitude was achieved.
• High sensitivities were demonstrated: 64.1-198 V A^-1 T^-1 (current-related) and 14.8-21.4 mV V^-1 T^-1 (voltage-related), with crosstalk below 4.7%.

Conclusions:

• The developed 3-axis Hall-effect sensor offers a simpler and promising alternative to current state-of-the-art devices.
• Its high performance and reduced offset make it suitable for precise magnetic field sensing.
• Potential applications include position feedback and power monitoring in automotive, industrial, and consumer electronics.