Micro Magnetic Field Sensors Manufactured Using a Standard 0.18-μm CMOS Process

Abstract

Micro magnetic field (MMF) sensors developed employing complementary metal oxide semiconductor (CMOS) technology are investigated. The MMF sensors, which are a three-axis sensing type, include a magnetotransistor and four Hall elements. The magnetotransistor is utilized to detect the magnetic field (MF) in the x-axis and y-axis, and four Hall elements are used to sense MF in the z-axis. In addition to emitter, bases and collectors, additional collectors are added to the magnetotransistor. The additional collectors enhance bias current and carrier number, so that the sensor sensitivity is enlarged. The MMF sensor fabrication is easy because it does not require post-CMOS processing. Experiments depict that the MMF sensor sensitivity is 0.69 V/T in the x-axis MF and its sensitivity is 0.55 V/T in the y-axis MF.

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

“…Li [16] 132 Lin [18] 690 530 91 Tseng [20] 6.5 6.5 0.4 Kimura [26] 140 Xu [30] 31 Yang [32] 366 365 Zhao [31] 264 This work 182 180 27.8…”

“…Compared with Oh's previous MMS [17], the sensitivity of the sensor increased by 13 times because of the vertical-type design and four-contact structure. A three-axis MMS, presented by Lin [18], was made using CMOS technology. The MMS consisted of four Hall elements and a magnetotransistor.…”

“…The experimental results showed that the MMS had a sensitivity of 6.5 mV/T in the x-axis MF and a sensitivity of 6.5 mV/T in the y-axis MF. The sensitivity of the MMS was lower than that of Li [16] and Lin [18]. A fluxgate MMS, which was presented by Lu [21], was produced using CMOS-MEMS technology.…”

“…The MMS was a 16 × 16 array of the Hall element, and the average sensitivity of the MMS was 0.140 mV/mT. 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. The MMS developed by Lin [18] was a three-axis sensor, but its cross-sensitivity was high because the structure of the MMS had only one magnetotransistor. Therefore, this work develops a three-axis MMS fabricated by the commercial CMOS process.…”