High density stand alone-fram

Abstract

Ferroelectric random access memory (FRAM) has been pursed as a new standalone memory due to its ideal memory properties such as fast random access in read/write mode and non-volatility with unlimited usage. However, FRAM has only achieved a limited success in limited applications because current FRAM is far behind its inherently outstanding properties. Recently, mega-bit density scaled FRAMs have been developed for creating big market. Many essential technologies have been built with the mega-bit density devices. Among those technologies, 1T1C COB (capacitor over bit line) cell structure is the most important because it can greatly reduce the cell size of FRAM compared to previous and current 2T2C FRAM. Although the recent demonstration gives a promising future for stand-alone FRAM application, current 1T1C COB FRAM still has incomparably large cell size factor compared to DRAM and Flash. This is one of the most challenging issues that FRAM faces for developing high-density stand-alone memory. Besides, there are still several design issues to be optimized for better performance and better reliability such as longer endurance and better retention. In this paper, the present status of high density FRAM technology will be firstly reviewed and the issues of current high density FRAM will be discussed with the possible solutions. Finally future technology will be projected.