Size‐reduced two‐dimensional integrated magnetic sensor fabricated in 0.18‐μm CMOS process

Abstract

Two‐dimensional integrated magnetic sensors have been investigated in order to reduce their size for use in a magnetic self‐levitation motor. The two‐dimensional integrated magnetic sensor investigated in this paper is composed of a 16 × 16 array of Hall sensors and fabricated by a 0.18‐μm complementary metal–oxide–semiconductor (CMOS) standard process. The sizes of the Hall elements are 1 × 1, 2 × 2, 3 × 3, and 6 × 6 μm2. Hall element of dimension 1 × 1 μm2was the minimum size in the fabrication process rule. The dimension of one pixel in which the Hall element was embedded was 20 × 20 μm2. The average sensitivity of the arrayed Hall sensors at four sizes was about 0.140 mV/mT with a DC magnetic field. The product sensitivity at four sizes of Hall sensors was about 0.089 mV/(mA·mT), which is better than that of our previous work. Degradation of the product sensitivity was not seen in reduced‐size Hall elements. These results reveal that a Hall element of size 1 × 1 μm2 has enough sensitivity for sensing the impeller position of a magnetically suspended motor. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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

“…The MMS developed by Li [16], Xu [30], and Zhao [31] were 1-axis MF sensors, and the MMS presented by Yang [32] was a 2-axis MF sensor. As shown in Table 1, the sensitivity of the MMS in this work in the x-and y-axis MF exceeded that of Li [16], Tseng [20], and Kimura [26]. The sensitivity of the MMS presented by Tseng [20] in the z-axis MF was lower than that of this work.…”

“…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…”

“…The MMS that combined spinning-current Hall elements and pick-up coils had a resolution of 210 μT in a bandwidth of 3 MHz. A two-dimensional MMS, proposed by Kimura [ 26 ], was made based on the CMOS technology. The MMS was a 16 × 16 array of the Hall element, and the average sensitivity of the MMS was 0.140 mV/mT.…”

“…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.…”

Suppression method of low-frequency noise for two-dimensional integrated magnetic sensor

“…15) In order to suppress abnormal vibration, small integrated two-dimensional magnetic sensor systems have been developed. [16][17][18] By the submicron CMOS fabrication process, the size of Si Hall elements has been made smaller. 17,18) In the previous work, 19) the two-dimensional magnetic field distribution from a Nd-Fe-B rare-earth permanent magnet was successfully measured using the two-dimensional magnetic sensor that consists of 2.7 × 2.7 µm 2 Si Hall elements placed in a 7 × 7 µm 2 pixel.…”