Freescale Semiconductor Produces First 24-Megabit-Memory Chip Based on Silicon Nanocrystals
Dr. Bruce White of Freescale Speaks to NWN About This Latest Chip Breakthrough And the Impact Nanotechnology Has on the Chip Industry.The 24-megabit memory chip produced by Freescale Semiconductor is a new type of memory technology that the company claims is cheaper, faster, and denser than traditional flash memory. Silicon nanocrystal memories fall under a new class of memory called thin-film storage that is expected to be an alternative to traditional embedded nonvolatile memory. The 24-Megabit chip is a major step toward replacing traditional flash memory.
Conventional floating gate-based memory requires a somewhat thick oxide surrounding a floating gate to insure appropriate data retention, and this requires high voltage to add and remove electrons from the floating gate. But thinning down the oxide may cause the charge to leak off of the floating gate. “By scaling flash memory using silicon nanocrystals, a single defect results in loss of charge from just one nanocrystal versus the whole floating gate, and reduces the operating voltages from +/-9V down to +/- 6V, thus reducing the memory module size by about a factor of 2,” explains Dr. Bruce White, Manager of Advanced Materials, Memories, and Interconnects at Freescale. “Reducing the operating voltage makes it easier to embed the memory with high performance logic. What used to take 11 lithography steps now only requires 4 lithography steps for a floating gate comprised of nanocrystals.”
While Freescale is excited about the new memory chip’s impact on its automotive and microcontroller technology, Dr. White tells NWN that a smaller memory chip has multiple potential consumer electronics applications, from cell phones to PDAs.
Nanotechnology is important to the semiconductor industry as it works towards keeping pace with Moore’s Law. For Freescale, “creating a self-assembly based, bottoms-up way of growing nanocrystals by using a chemical vapor deposition process allows us to have control of the density and size of the nanocrystals,” notes Dr. White. He observes, “When you look at the nano industry, it encompasses both a bottoms-up (self-assembly) and tops-down (controlling the size by lithography and deposition) approach. There is a tops-down version of nanotech in the semi industry. [In relation to building memory], we need to step back and look at merging of the tops-down and bottoms-up approaches to enable continued scaling.”