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

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.

Manufacturing and characterization of CMOS-MEMS magnetic field microsensors with isolated cavities

“…These isolated cavities significantly decrease substrate leakage current, thereby boosting the sensitivity of the MF microsensor. The sensitivity of the MF microsensor in this work exceeds that of microsensors fabricated by Du et al [23], Sileo et al [24], Chen et al [25], Zhao et al [26] and Wu et al [27].…”

“…The microsensor's structure incorporates AlGaAs/InGaAs/GaAs multilayer materials, and its sensitivity is measured at 0.03 V T −1 . Chen et al [25] proposed a three-axis MF microsensor manufactured using the CMOS process. The structure of the MF microsensor includes two magneto field-effect transistors to enhance sensitivity.…”

Foundry Service of CMOS MEMS Processes and the Case Study of the Flow Sensor

“…Figure 4a shows the deposition of the polysilicon above the substrate; Figure 4b represents the CMOS layer with an additional pattern of contact layer; Figure 4c depicts the standard CMOS layer with amorphous SiO2, metal M1-M6, metal 7 hard mask, and a passivation layer; Figure 4d developed the thick photoresist layer to perform the patterning; lastly, Figure 4e,f shows anisotropic silicon oxide etching and XeF2 isotropic silicon etching, respectively. The powerful CMOS MEMS foundry service in Taiwan has contributed to a variety of MEMS microsensor developments such as magnetic sensors [90,[98][99][100][101][102], humidity sensors [103][104][105][106][107][108], gas sensor [54,63,[109][110][111][112], pressure sensors [16,78,[113][114][115][116][117], thermoelectric energy harvesters [118][119][120][121][122], strain sensors [37,40,53], thermal sensors [123][124][125][126][127]<...…”

“…In the earlier stage, the CMOS MEMS process had a larger CD or minimum line width in the academic labs of Europe and USA [73][74][75][76][77][78][79][80]. As the CD kept on decreasing to 0.8 µm [35] The powerful CMOS MEMS foundry service in Taiwan has contributed to a variety of MEMS microsensor developments such as magnetic sensors [90,[98][99][100][101][102], humidity sensors [103][104][105][106][107][108], gas sensor [54,63,[109][110][111][112], pressure sensors [16,78,[113][114][115][116][117], thermoelectric energy harvesters [118][119][120][121][122], strain sensors [37,40,53], thermal sensors [123][124][125][126]…”

Manufacturing and Characterization of Three-Axis Magnetic Sensors Using the Standard 180 nm CMOS Technology

“…According to the x/y-MSE structure (Figure 1) and the z-MSE structure (Figure 2), the x/y-MSE and z-MSE layouts were devised. In accordance with the x/y-MSE and z-MSE layout, the three-axis MS was fabricated based on the standard CMOS process from Taiwan Semiconductor Manufacturing Company (TSMC) [31]. Figure 9 shows a picture of the three-axis MS after the CMOS process.…”