Resistive RAM Instability Problems Solved Making 28nm Embedded Apps a Reality
28-07-2015 | By Paul Whytock
The problems of filament instability in resistive RAM (RRAM) technology have been cracked in a joint effort by Japanese electronics conglomerate Panasonic and research centre Imec. The two organizations say this paves the way to making 28nm embedded applications a feasible reality.
RRAM is essentially non-volatile memory that changes the resistance across a dielectric solid-state material, often referred to as a memristor. It is similar in concept to conductive-bridging RAM (CBRAM) technology which involves one electrode providing ions that dissolve readily in an electrolyte material.
RRAM intentionally forms defects in a thin oxide layer called oxygen, and the motion of oxygen ions and vacancies in the oxide is comparable to the flow of electrons in a semiconductor.
Panasonic and Imec are not alone in their interest in RRAM technology, it is also being developed by a variety of different companies, and some of them have reached the stage of filing patent applications that relate to various versions of the technology.
However, despite this technology being perceived as a potential replacement for conventional flash memory, there are still worrying questions about the cost and performance benefits. These doubts mean that some companies are not actively investing in technology development and have decided on a watch-and-wait approach.
This, however, could change soon with the discovery that the high-? Gate dielectric HfO2 can be used as a low-voltage RRAM.
Imec and Panasonic fabricated a 40nm TaOx-based RRAM with precise filament positioning and high thermal stability.
The was created using a combination of process technologies such as low-damage etching, cell side oxidation and an encapsulated cell structure with an Ir/Ta2O5/TaOx/TaN stacked film structure featuring a filament at the cell centre. Doing this produced a 2Mbit 40nm RRAM cell with precise filament positioning and high thermal stability.
By overcoming filament instability in RRAM, Imec and Panasonic have resolved one of the important issues that impact the memory state during a read operation in resistive memory.
