A 10nm-Thick Hafnium Zirconium Oxide Piezoelectric Transducer for Extreme Miniaturization of Integrated Sensors and Actuators

This paper reports the thinnest ever-reported piezoelectric transducer for realization of extremely miniaturized nanomechanical sensors and actuators. A 10nm hafnium-zirconium-oxide (Hf
_0.5
Zr
_0.5
O
₂
) (HZO) film is engineered through atomic-level stacking, capping with titanium-nitride electrodes, and proper rapid-thermal-annealing treatment to promote non-centrosymmetric orthorhombic crystallization with large piezoelectric properties. The developed 10nm HZO transducer is used for excitation of a silicon-based multi-morph nanomechanical resonator, with an overall thickness of ~350nm. The developed resonator, along with 120nm aluminum-nitride (AlN) transduced counterparts, are also used as test-vehicles to characterize the ferroelectric and piezoelectric properties of the HZO film. Benefiting from large piezoelectric coefficient (e
_31,HZO
≈ 2.3
_e31AlN
), fully conformal deposition, and CMOS-compatibility, ALD-deposited HZO transducer paves the way for radical miniaturization of nano-systems, realization of 3D nano-actuators, and extreme frequency scaling and monolithic integration of RF front-ends for the emerging 5G wireless communication systems.