1Mb Non-Volatile Random Access Memory Using Oxide Semiconductor

Abstract

We propose Non-Volatile Oxide Semiconductor Random Access Memory (NOSRAM) that is a novel memory including a transistor using an oxide semiconductor, In-Ga-Zn Oxide. OS transistors feature extremely low leakage current of about 100-600 yA/μm (1 yA = 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-24</sup> A) at 85°C for example, and are applicable to memory elements. Our prototype of a 1Mb NOSRAM has achieved 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> write cycles, no need of erasing operation, low-voltage high-speed write, and the like. The NOSRAM is not theoretically degraded by data write while a flash memory is degraded every time data are written; therefore, our NOSRAM has the possibility to be used as a non-volatile memory superior to a flash memory.