Magnetic Micro Sensors with Two Magnetic Field Effect Transistors Fabricated Using the Commercial Complementary Metal Oxide Semiconductor Process.

Wei-Ren Chen,Cheng-Chih Hsu,Ching-Liang Dai,Po-Jen Shih,Yao-Chuan Tsai

doi:10.3390/s20174731

Abstract

The fabrication and characterization of a magnetic micro sensor (MMS) with two magnetic field effect transistors (MAGFETs) based on the commercial complementary metal oxide semiconductor (CMOS) process are investigated. The magnetic micro sensor is a three-axis sensing type. The structure of the magnetic microsensor is composed of an x/y-MAGFET and a z-MAGFET. The x/y-MAGFET is employed to sense the magnetic field (MF) in the x- and y-axis, and the z-MAGFET is used to detect the MF in the z-axis. To increase the sensitivity of the magnetic microsensor, gates are introduced into the two MAGFETs. The sensing current of the MAGFET enhances when a bias voltage is applied to the gates. The finite element method software Sentaurus TCAD was used to analyze the MMS’s performance. Experiments show that the MMS has a sensitivity of 182 mV/T in the x-axis MF and a sensitivity of 180 mV/T in the y-axis MF. The sensitivity of the MMS is 27.8 mV/T in the z-axis MF.

Highlights

Magnetic micro sensors (MMS) play an important role in measurement of magnetic field and are applied in various fields
The x/y-magnetic field effect transistors (MAGFETs) was used to sense the magnetic field (MF) in the x- and y-axis, and the z-MAGFET was utilized to detect the MF in the z-axis
The z-MAGFET increased the mobility of carriers in the surface of the p-substrate and enhanced the sensitivity of the magnetic micro sensor (MMS)

Summary

Introduction

Magnetic micro sensors (MMS) play an important role in measurement of magnetic field and are applied in various fields. Oh [2], was developed using a microelectromechanical system (MEMS) magnetic micro sensor (MMS). Li [16] developed an MMS with a conducting magnetic structure using a CMOS process. A three-axis MMS, proposed by Tseng [20], was made using a standard CMOS process. The sensitivity of MMS approached that of Li [16] but was smaller than that of Lin [18] These magnetic micro sensors [16,17,18,19,21,23,25,26] fabricated by CMOS technology were 1-axis MF sensors. This work develops a three-axis MMS fabricated by the commercial CMOS process. The x/y-MAGFET measured the MF in the x- and y-axis, and the z-MAGFET measured the MF in the z-axis

Structure of the MMS

Fabrication of the MMS

Results

Conclusions