A high sensitivity hall sensor fabricated on a SOI wafer using surface micromachining technique

Hall sensors of high sensitivity have been designed and fabricated using the Micro-Electro-Mechanical System (MEMS) process. This paper presents the design and fabrication techniques used to obtain high sensitivity Hall sensors on a thin film polyimide flexible substrate. The devices are fabricated on a Silicon-on-Insulator (SOI), with boron-doped p-type Silicon as the active layer, using surface micromachining principles. The arrays of Hall devices are further transferred to a flexible substrate using a combination of wet and dry micromachining processes. The manufactured devices are stable over a range of temperature displaying relatively high magnetic sensitivity values. The recorded device sensitivities are in the range of 10μV/mA-G. The fabrication process aims at fabricating devices on a flexible substrate that enables to curve the Hall probes and thus use them for the measurement of radial magnetic fields and magnetic fields on curved surfaces. The volume of the active region is 1000×100×2μm.