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 works by changing 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.
What RRAM does is intentionally forms defects in a thin oxide layer called oxygen and the motion of oxygen ions and vacancies in the oxide are 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 question about the cost and performance benefits. These doubts do mean that some companies are not actively investing in the development of the technology 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.
What Imec and Panasonic have fabricated is 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. By doing this a 2Mbit 40nm RRAM cell with precise filament positioning and high thermal stability was produced.
By overcoming filament instability in RRAM Imec and Panasonic have resolved one of the important issues that impacts the memory state during read operation in resistive memory.