Executive Summary : | There is a huge demand in solid-state magnetic sensors due to their applications in the automotive, healthcare sector, consumer electronics, and aerospace technologies. Detection of the low-intensity magnetic field at low frequency with a highly sensitive magnetic sensor is one of the promising technologies for a large variety of applications, such as geological surveys, healthcare sector, and detection of submarine objects. Currently, few sensing technologies such as superconducting quantum interference devices (SQUIDs), fluxgate, giant magnetoimpedance (GMI), or atomic magnetometers are capable to detect less than pT fields at very low frequency. However, these technologies have limitations. For example, SQUID is bulky, require low temperature and expensive whereas GMI has issue with sensitivity and atomic magnetometer is a complicated system. Thus, scientists are focusing on highly sensitive, small size, low power consumption device for ultra-weak magnetic field. MgO based tunneling magnetoresistance (TMR) sensor is a prime candidate for the next generation of highly sensitive magnetic sensors. However, the detectivity of TMR is limited by intrinsic noise arises from electric and magnetic components. TMR detectivity can be improved by two approaches: integrating multiple TMR sensors in series or using magnetic flux concentrator. In TMR series, the noise factor is multiplied with increase in no. of sensing elements. On the other hand, researchers have focused on magnetic flux concentrator (MFCs) in TMR to improve sensor sensitivity as well as detectivity. A proper trade-off between no. of MTJ pillars and MFC will give pT fields detectivity. Through this project, the state-of-the-art in pico-Tesla magnetic sensing technologies at room temperature will be developed. To achieve this, two approaches (i) on chip MFC and (ii) external MFC will be used with TMR sensor technology. The sensor geometry will be optimized including MFC, lateral permanent magnets and TMR to enhance the detectivity. With proper architecture, a low-cost single chip integrated high performance TMR sensor with high magnetic sensitivity and low noise will be fabricated. |