Emerging memories

Abstract

a b s t r a c tMemory is a key component of any data processing system. Following the classical Turing machine approach, memories hold both the data to be processed and the rules for processing them. In the history of microelectronics, the distinction has been rather between working memory, which is exemplified by DRAM, and storage memory, exemplified by NAND. These two types of memory devices now represent 90% of all memory market and 25% of the total semiconductor market, and have been the technology drivers in the last decades. Even if radically different in characteristics, they are however based on the same storage mechanism: charge storage, and this mechanism seems to be near to reaching its physical limits. The search for new alternative memory approaches, based on more scalable mechanisms, has therefore gained new momentum. The status of incumbent memory technologies and their scaling limitations will be discussed. Emerging memory technologies will be analyzed, starting from the ones that are already present for niche applications, and which are getting new attention, thanks to recent technology breakthroughs. Maturity level, physical limitations and potential for scaling will be compared to existing memories. At the end the possible future composition of memory systems will be discussed.

BiFe1–xCrxO3 Ferroelectric Tunnel Junctions for Neuromorphic Systems

“…After dominating the semiconductor memory market for the past four decades because of their simple structure (one transistor–one capacitor) and fast write/read access (10 ns/10 ns), dynamic random access memories (DRAM) have now reached their scalability limit. , Among the strongest contenders to replace DRAM technology are ferroelectric tunnel junctions (FTJs). , These memory devices have the advantages of being nonvolatile and highly scalable, in addition to displaying a high switching speed (10 ns) and a high endurance (4 × 10 6 cycles) and operating at low switching energies. Their structure is relatively simple (one transistor–one resistor) and similar to PC-RAM, where one cell resistor is composed of an ultrathin (a few nanometers) ferroelectric layer deposited between two conductive electrodes. , FTJs exploit resistive switching, a reversible process that consists of toggling between a high-resistance state (HRS) and a low-resistance state (LRS) via bipolar voltages to the device. − These two states correspond to the logical “0” and “1” in binary code directly related to the orientation of ferroelectric domains.…”

A Fabrication Process for Emerging Nanoelectronic Devices Based on Oxide Tunnel Junctions

“…Resistive memories are promising devices that could be part of the memories catalog or eventually replace nonvolatile flash memory in the future [21,22]. Among all competing technologies for the next generation of solid-state memory, RRAM combines all the virtues requested by industry [1], which explains the tremendous research efforts that have been carried out by research groups in both universities and microelectronic industries.…”

Low-power electronic technologies for harsh radiation environments

“…Specifically FeRAM is sensitive to contamination during the back-end-process integration, while PCRAM is temperature-sensitive which makes it ill-suited for space and nuclear applications. 67 MRAM and ReRAM are considered as the forerunners due to their excellent performance, CMOS compatibility, and radiation tolerance.…”