Highly-scaled programmable metallization cell (PMC) memory devices

Nanoscale memory devices are becoming more familiar in our generation, jumping into our daily life in portable and wireless devices. Factors driving the development of nano memory devices are the necessity to maintain the information for a long time without refreshing power, lower power consumption, high speed of data write/erase and a large number of write cycles. To introduce a new device to meet all the requirements, we are investigating a promising nano technology, Programmable Metallization Cell memory (PMCm) which uses electrodeposition in chalcogenide electrolyte materials.; This dissertation introduces the chalcogenide glasses: basic characterization, glass formation, formation of silver doped Ge-chalcogenide glasses by photodiffusion of silver in thin films, and electrochemistry. In an attempt to understand the structure and diffusion mechanisms of these glasses, the structure of the film surface has been examined using field emission microscopy (FESEM), energy dispersive x-ray analysis (EDAX), X-ray diffraction (XRD), and Raman spectroscopy. The solid electrolyte was created using diffusion mechanisms applying either photodiffusion or a combination of photo and thermal diffusion. We show that thermally stimulated Ag diffusion in high vacuum combined with photo illumination leads to a nano-phase separated material which has a dispersed Aq ion-rich material with an average crystallite size of 6--10 nm in a glassy insulating Ge-rich continuous phase.; The formation of highly-scaled programmable metallization cell memory devices in sub-100 nm openings using Se-rich chalcogenide solid electrolytes has been demonstrated. Electron beam lithography (EBL) patterning was used for the fabrication of such small vias in polymethylmethacrylate (PMMA) dielectric. Two terminal devices were created in the vias with an oxidizable silver anode and an inert cathode sandwiched with the chaicogenide electrolyte. This device has an intrinsically high resistance; it can be rapidly switched to a low resistance state at extremely low voltage and current via electrodeposition of the silver in the electrolyte. An opposite bias will reverse the ion current until the excess silver has been removed, returning the device to a high resistance state. The nanoscale devices write at an applied bias as low as 0.2 V, erase by -0.5 V, and fall from over 107 O to a low resistance state (e.g., 104 O for a 10 muA programming current) in less than 100 nsec. Cycling appears excellent with projected endurance well beyond 1011 cycles.