Piezoelectric aluminum nitride dual-beam relays for mechanical computing

The continuous scaling of the metal-oxide-semiconductor-field-effect-transistor (MOSFET) has led to the emergence of some key issues, like high standby leakage and inability to rapidly scale supply voltages, which are due to the fundamental physics of operation of the CMOS transistor. No alternatives or roadmap for solving these challenges has yet been identified. The recognition of this problem by the industry has led to a demand on the development of alternative technologies such as mechanical relays. This work describes the design, fabrication and testing of dual-beam mechanical relays for the development of logic elements that can be integrated with present day CMOS technology or, in the future, act as possible MOSFET replacement devices. The dual beam design is a stress-resilient design that helps in realizing nano-switching gaps. In addition, the introduction of a new actuation technique based on body-biasing enables achieving very low switching voltages ( 10 orders of magnitude). All these features make the dual-beam mechanical relay capable of realizing computing systems that can operate with unprecedentedly low operating voltages in the order of tens of mVs. Scaling relationships are presented to offer a projection of the ultimate energy savings that this technology will enable. To this extent, experimental results showing the demonstration of the first piezoelectric actuator formed by 50 nm AlN piezoelectric films are discussed. Also the thinnest piezoelectric switch, realized by 100 nm AlN films, is briefly presented. Finally, this thesis will address the main remaining challenges that still need to be overcome to synthesize low energy nanomechanical computing components.