Looking for Mr. Goodoxide

Abstract

B reaking up is hard to do-especially after 40 years together. It's even tougher when those 40 years were spent constantly side by side, fostering an upstart technology that has changed the world. Most everyone has heard that silicon is the material primarily responsible for the miraculous surge in computing power that is reshaping society. That's true, but silicon couldn't have done it alone. wellknown semiconductor's oxide, which chip makers grow or deposit on exposed silicon surfaces, has also played a crucial role. Little noticed outside the semiconductor industry, silicon dioxide has supported and protected silicon, as well as facilitated the element's special electronic properties. The guys like us who work with the stuff every day consider silicon dioxide the greatest gift from God, says John S. Suehle of the National Institute of Standards and Technology (NIST) in Gaithersburg, Md. Nonetheless, the semiconductor industry now wants to divorce silicon from its loyal oxide. first signs of a breakup came nearly a decade ago, when one sector of the industry-makers of random-accessmemory chips-ran into problems with the material and found ways to pair silicon with another compound, silicon nitride. Today, the disaffection is spreading to computing circuits. Circuit features are becoming so small that chip makers are battling on many fronts to keep up with the pace of change (SN: 11/8/97, p. 302). In the confines of smaller circuits, silicon dioxide's even-handed skill at managing passels of unruly charges has become a flaw. Consequently, research groups in the industry and elsewhere are searching for alternate materials. Although they don't know what will successfully replace silicon dioxide, manufacturers are specifying new machinery and otherwise making accommodations to handle likely alternatives in their production lines. Chip makers are already using some substitute materials on a limited scale in their products. If we can't replace silicon dioxide, it's a showstopper for device scaling-the main process by which the industry has made circuit elements smaller and smaller, says James H. Stathis of the IBM Thomas J. Watson Research Center in Yorktown Heights, N.Y semiconductor industry will part with silicon dioxide only reluctantly. Chip makers are chafing at the uncertainty and expense of switching to what may prove to be a less-than-perfect substitute, electronics specialists say. Circuit manufacturers would do much worse, however, not to change, they add. Unless the divorce takes place-and soon-the astounding pace of innovation on which the semiconductor industry thrives could slacken for the first time.