Report Robert Κ. Lowry Harris Semiconductor Melbourne, Fla. 32901
ANALYTICAL
CHEMISTRY and the
MICROCHIP
Figure 1. Wafer of digital-to-analog converter circuits 0003-2700/85/0357-023A$01.50/0 © 1985 American Chemical Society
During the past two decades our business and personal lives have been truly revolutionized by microelectron ic computing devices. The microelec tronics industry has packed ever-in creasing amounts of computing power into ever-smaller geometries on inte grated circuit (IC) chips. Electronics engineers continue to conceive, design, and assemble into powerful systems increasingly sophisticated microcom puting devices. An integrated circuit is an intercon nected array of electronically active and passive components, built in and on a single semiconducting substrate. The substrate for the majority of to day's ICs is pure, single-crystal silicon containing controlled levels of dop ants. Dopants provide charge carriers to render specific spatial regions of the silicon lattice semiconducting. Dop ants such as pentavalent phosphorus (>4 valence electrons) occupying lat tice sites, produce silicon that con ducts by negative charge, i.e., n-type semiconductors. Similarly, dopants such as trivalent boron (
