Report Robert K. Lowry
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Harris Semiconductor Melbourne, Fla. 32901
ANALYTICAL
CHEMISTRY
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 microelectronics industry has packed ever-increasing amounts of computing power into ever-smaller geometries on integrated circuit (IC) chips. Electronics engineers continue to conceive, design, and assemble into powerful systems increasingly sophisticated microcomputing devices. An integrated circuit is an interconnected array of electronically active and passive components, built in and on a single semiconducting substrate. The substrate for the majority of today’s ICs is pure, single-crystal silicon containing controlled levels of dopants. Dopants provide charge carriers to render specific spatial regions of the silicon lattice semiconducting. Dopants such as pentavalent phosphorus (>4 valence electrons) occupying lattice sites, produce silicon that conducts by negative charge, i.e., n-type semiconductors. Similarly, dopants such as trivalent boron (
