cover feature nanoelectronics
Can Nanoelectronics Deliver a Universal Memory? With semiconductor structures approaching atomic scale, the search for scalable technologies has gotten serious—and promising.
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by John Donovan, Editor-in-Chief As semiconductor line widths move to 32 nm and below, Moore’s Law is starting to run headlong into the laws of physics. Gate leakage below 32 nm—where doping variations of several atoms may cause a gate to fail—makes capacitor-based DRAM and floating-gate flash memories increasingly unreliable. High-k materials and metal-gate structures are a shortterm fix that won’t scale very far. The next generation of chips—logic, and in particular memories—needs a solution in the nanoscale region, where the Holy Grail of an ultra-lowpower and ultra-fast, non-volatile “universal memory” is reputedly waiting to be found. After several years of hype about its potential, the fledgling nanoelectronics industry could be in real trouble if it doesn’t start delivering real products into the market soon. This article will focus on nanomemory technologies that are already available or seem likely to be commercialized in the near future.
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PORTABLE DESIGN
One such technology, magneto-resistive RAM (MRAM), has recently started shipping in volume, aiming to replace SRAM and flash in a variety of applications. MRAM is a leading contender for the title of “universal memory,” combining the speed of SRAM at a comparable cost structure and durability several orders of magnitude better than flash. While MRAM is the first “next-generation memory” out of the chute, other more exotic technologies are threatening to follow suit, including silicon nanocrystals, phase-change memories and carbon nanotubes. In terms of scaling, molecular memory—yes, we’re being serious here—is in a class by itself.
MRAM
Magneto-resistive RAM (MRAM) devices store data as a magnetic state rather than a charge. Each memory element in an MRAM consists of a magnetic tunnel junction (MTJ).