Creating memories for all to share
01 October 2006
Several companies are claiming breakthroughs in memory technology, reports CAROLINE HAYES, from a new version of NAND for multimedia-rich devices, to new business groups.
The demand for NAND flash memory is expected to increase dramatically in the five year period to 2010. ISuppli forecasts that the NAND flash market would grow from $11.9billion in 2005 to $24.70billion in 2010. Considering the price falls, it is currently around a third of the cost of NOR flash, and increasing uses, the reason for the interest in NAND flash becomes clear. However, price rises have seen some of the forecasts reduced, with iSuppli trimming back its 2006 market worth of $16billion to $13.8billion, realising a 28 per cent global growth from 2005 to 2006.
NAND flash is principally used in removable storage cards and USB drives. According to iSuppli, these account for 56 and 20 per cent respectively. This dominance is being challenged by MP3 players. Both analyst companies attribute the NAND flash success to its use by MP3 players. ISuppli believes MP3 players will consume 21.6 per cent, worth around $2.1billion followed by USB flash drives as the third largest application for NAND flash with around 17 per cent market share last year. Similarly, both analyst houses agree that Apple’s iPod can claim responsibility for the increase in both capacity and orders. NAND flash use in MP3 players has increased as hardware like the Apple iPod are available with two and 4Gbyte capacities which store music files on NAND-type flash memory rather than hard disk drives. Apple has created a trend among MP3 player manufacturers to replace hard drives with NAND flash storage.
Msystems (www.m-systems.com) claims to have ‘revolutionised’ NAND flash manufacturing, with its x4 technology. It is described by president and CEO, Dov Moran, as the ‘highest peak in a 16year trail…and the culmination of five years of dedicated research and development.’
NAND flash storage has become the affordable memory of choice as the price/GByte has seen a decrease of more than 80 per cent since 2003. The target applications for the x4 NAND components are consumer electronics devices, such as digital audio players, consumer solid state devices, portable media players, digital video cameras, GPS devices, multimedia and music handsets, memory cards and USB flash drives.
By maximising the 4bit/cell NAND flash, the company believes it can provide the storage needed for the next generations of multimedia-rich, consumer electronics devices, such as the Sony smartphone pictured here, where the use of MP3 players and digital cameras increase the memory content.
The x4 technology is a proprietary flash management and control algorithms combination that is designed to do what was previously discounted, make use of 4bit/cell NAND flash. This course of action had previously been deemed to be impractical and physically impossible.
The x4 NAND components, due to be available next year, are made up of the 4bit/cell NAND flash media and a x4 technology controller. According to msystems, the technology can save NAND flash manufacturers over 30 per cent compared with advanced 2bit/cell MLC (multi-level cell) NAND flash wafers, manufactured through equivalent lithography.
Compared with MLC NAND flash, the bit density is doubled and quadrupled compared with SLC (single-level cell) NAND flash. All of this is achieved using the same manufacturing processes.
Also cramming in more useable memory in a smaller space, Freescale’s MRAM (magnetic random access memory). In essence, MRAM combines the storage capacity of DRAM, the speed of SRAM and the non-volatility of flash. The singular difference is that it retains information when the device’s power is switched off and is able to start up instantly without software boot up time before being operational. For this reason it is mostly used in computers, but the power saving advantage means it is also being designed in to handheld, portable devices. Conventionally, DRAM and SRAM technologies require a constant electrical power to retain the stored data. To avoid it being lost, when the device is switched off, the data is copied and saved to the hard disk. What causes the delay at start-up with these two memories is that the software is copied from the hard disk and accessed by the memory.
Freescale’s MRAM cell (right) is x4 smaller than a six-transistor SRAM cell, targeting the memory at mid-range performance SRAM applications (www.freescale.com). The magnetic tunnel junction sits on top of a transistor, reducing both space and component count. The 4Mbit MRAM has an access time of 35nsec (both read and write), setting it against mid-range SRAM devices and as a replacement for batterybacked SRAM. High-speed SRAM can reach less than 10nsec access times. Produced on a 0.18ìm process, the MRAM cell size is x4 smaller than that of SRAM devices. This is expected to reduce further when Freescale moves to a 90nm process, expected to deliver 64Mbit MRAM.
SRAM, although a more conventional memory technology, still has room for some innovation and upgrading. One piece of news reflecting this is the sampling of the first Quad Data Rate II+ (QDRII+) and DDRII+ (double data rate II+) SRAMs by Cypress (www.cypress.com).
The chips deliver high-density, high bandwidth performance, claimed to enable up to 50 per cent more system-level bandwidth than existing QDRII and DDRII devices. The QDRII+ and DDRII+ SRAMs accelerate read/write capabilities in dataintensive applications such as switches, routers, servers, storage appliances, wireless basestations and test equipment.
The two SRAMS operate at speeds of up to 500MHz and offer a bandwidth up to 72Gbit/sec in a 165pin, FBGA. They are manufactured using the company’s 90nm RAM9 process technology.
Another name in memory, Infineon, announced that its memory products business will be separated from the rest of the business group and operate as a new company, called Qimonda (www.qimonda.com).
The subsidiary is based, like its parent, in Munich and from 1 May this year has been the fourth largest DRAM company, using all of Infineon’s memory business and accessing five 300mm manufacturing sites in North America, Europe and Asia. It also operates five R&D facilities, including Infineon’s lead R&D site in Dresden, Germany.
The subsidiary has stated that it plans to move from 90nm to 75nm technology nodes and will expand its primary DRAM focus to a broader memory portfolio, such as flash.
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