Comms chips

Intel Shows Tiny Transistor

At the Silicon Nanoelectronics Workshop in Kyoto, Japan, this week, Intel Corp. (Nasdaq: INTC) gave a sneak preview of a silicon transistor with a gate length of just 20 nanometers, or 0.02 microns, which it claims will be the world's fastest (see Intel Extends Moore's Law).

This breakthrough means that it will be possible to keep shrinking transistors while keeping the design process and fabrication techniques predominantly the same as they are today, until at least 2010. In other words, Moore's Law -- an empirical rule which states that the number of transistors on a chip doubles every two years -- hasn't run out of steam just yet (see What is Moore's Law?).

That's good news for chip makers. Every time transistor dimensions shrink by one third, the number of chips that can be squeezed on a wafer doubles, the speed increases, the operating voltage drops, and the production cost is roughly halved.

Intel expects to put its 20nm transistor into production in 2007 as its 0.045 micron process generation, which will hit speeds of 20 GHz and operate at less than one volt. For comparison, today's state-of-the-art silicon chips use 0.13 micron process technology.

Now for the bad news. Intel has only made a handful of these transistors, and they're all of the nMOS (n-doped metal oxide semiconductor) type. To make real circuits, transistors have to be made in complementary pairs of nMOS and pMOS -- hence the name complementary metal oxide semiconductor (CMOS) technology. The performance of these chips has yet to be verified.

What's more, these transistors may represent a real limit to standard CMOS technology. That's because the gate oxide -- a layer that prevents the metal on the gate contact from short-circuiting directly to the silicon underneath it -- is only three atoms thick. If the gate oxide were any thinner than this, the transistor would stop working.

There are other approaches to making transistors, but these would require new and more complicated processing techniques. Intel strongly favors pushing existing CMOS technology to its limits, says Robert Chau, director of transistor research at Intel's components research group.

—Pauline Rigby, Senior Editor, Light Reading, http://www.lightreading.com

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