AlN Ultra-Thin Chips Based Flexible Piezoelectric Tactile Sensors

This paper presents an aluminium Nitrate (AlN) ultra-thin chip based bendable piezoelectric pressure sensor. The piezoelectric AlN layer (500nm-thick) was grown on silicon (Si) substrate and following this the thickness of Si was reduced to ~35µm through a backside lapping process. The debonding of chip from thinning chuck was achieved through a PMMA sacrificial layer-based stress relieving technique. The capacitance of a parallel plate capacitor fabricated on the AlN-Si substrate exhibits a similar value of 2.53 ± 0.01 nF before and after thinning, confirming the damage free thinning and debonding of UTCs. The performance of flexible AlN UTC based sensor was evaluated under dynamic pressure and compared with the bulk AlN-Si. The results demonstrate a similar tactile performance with a negligible change in piezovoltage (~0.001 V) before and after thinning. This simple technique could be further explored to develop high resolution flexible POSFET devices for tactile sensor applications.