Fabrication and characteristics of magnetic field sensors based on nano-polysilicon thin-film transistors

A magnetic field sensor based on nano-polysilicon thin films transistors (TFTs) with Hall probes is proposed. The magnetic field sensors are fabricated on < 100 > orientation high resistivity (p > 500 Omega.cm) silicon substrates by using CMOS technology, which adopt nano-polysilicon thin films with thicknesses of 90 nm and heterojunction interfaces between the nano-polysilicon thin films and the high resistivity silicon substrates as the sensing layers. The experimental results show that when V-DS D 5.0 V, the magnetic sensitivities of magnetic field sensors based on nano-polysilicon TFTs with length-width ratios of 160 mu m/80 mu m, 320 mu m/80 mu m and 480 mu m/80 mu m are 78 mV/T, 55 mV/T and 34 mV/T, respectively. Under the same conditions, the magnetic sensitivity of the obtained magnetic field sensor is significantly improved in comparison with a Hall magnetic field sensor adopting silicon as the sensing layers.