AMD claims breakthroughs in transistor design

By Steve Malone

Posted on 2 Apr 2003 at 11:09

AMD has announced that it has built a high-performance transistor that is up to 30 per cent faster than the best of the current generation of PMOS (P-channel metal-oxide semiconductor) transistors. The new transistor technology is based on the process known as Fully Depleted Silicon-on-Insulator.

Although AMD is not releasing full details until June, fully depleted SOI is based on ultra thin wafers of silicon in the tens of nanometers. The advantage being that they use very little power and are therefore seen as ideal for high performance, low power consumption devices emerging over the next five years.

The technical problem, however, with the thin channels used in fully depleted SOI is that it tends to force up the resistance through the source and drain areas, which in turn slows the device down. A few, mainly Far Eastern companies - notably Oki and Samsung have turned out product based on FD-SOI. However, the holy grail is to produce wafers suitable for the kind of VLSI technology markets where AMD is a player.

AMD is also claiming another industry first with a strained silicon transistor achieving 20-25 per cent higher performance than conventional strained silicon devices through the successful use of metal gates.

It has been known that carrier mobility is increased if the crystal lattice of silicon is stretched. Therefore if silicon is placed on say, Silicon/Germanium which has a slightly wider lattice, the Silicon is stretched or 'strained' and mobility is increased. A strained Silicon transistor uses this layer as the channel layer and therefore mobility is increased.