Non-volatile memory device based on mobile protons in SiO₂ thin films

Abstract

The silicon/silicon-dioxide system provides the cornerstone of integrated-circuit technology¹. Since the introduction of devices based on this system, the (largely deleterious) effects on device operation of mobile and trapped charges in the oxide layer have been studied in great detail. Contamination by alkali ions, for example, was a major concern in the early days of metal-oxide-semiconductor device fabrication². But not all SiO₂ impurities are undesirable: the addition of hydrogen, for example, has the beneficial property of rendering charge traps inactive¹. Here we show that mobile H⁺ ions introduced by annealing into the buried oxide layer of Si/SiO₂/Si structures, rather than being detrimental, can form the basis of a non-volatile memory device. These mobile protons are confined to the oxide layer, and their space-charge distribution can be controlled and rapidly rearranged at room temperature by an applied electric field. Memory devices based on this effect are expected to be competitive with current state-of-the-art Si-based memories, with the additional advantage of simplicity—only a few standard processing steps are required.