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

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.