Effect of SiNx Deposition Temperature on Performance Characteristics of AMR Angle Sensors

This study investigates the impact of SiNx passivation layer deposition temperatures on the performance of the anisotropic magnetoresistive (AMR) angle sensors. While passivation layers like SiNx enhance chemical stability and corrosion resistance, they may also decrease sensor sensitivity. We contribute the loss in sensitivity to the variation in the deposition conditions, mainly the deposition temperature. Experimental results indicate that AMR devices deposited with SiNx at $200^{\circ} \mathrm{C}$ demonstrate an improved device sensitivity of 1.5mV/Gs, closest to uncoated devices of 1.6mV/Gs, facilitating the sensitivity deterioration issue. The result of this work may promote the application of AMR devices in harsh environments due to the inclusion of the passivation layer. Further work is needed for the understanding the fundamental reason behind sensor performance deterioration.