In manufacturing microelectronic and optoelectronic devices, thin solid films of various sorts are routinely deposited and etched using low pressure, weakly ionized plasmas. The term “plasma” in this context implies an ionized gas with nearly equal numbers of positive and negative charges. This definition is not very restrictive, so. there are an enormous number of phenomena that are termed plasmas. For example, very hot, magnetized, fully ionized plasmas exist in stellar environments and thermonuclear fusion experiments. High temperature electric arcs are a form of plasma as well. In contrast, the plasmas used in electronic materials processing are near room temperature and the gas is usually weakly ionized. Indeed, due to the sensitivity of electronic devices to high temperatures, their low operating temperature is one of the major advantages of plasma processes.

Plasma processing is attractive because of two important physiochemical effects: energetic free electrons in the plasma (heated by applied electric fields) dissociate the neutral gas in the plasma to create chemically reactive species; and free positive ions are accelerated by the plasma electric fields to surfaces bounding the plasma. Reactive species created in the plasma diffuse to surfaces and adsorb; wafers to be processed are typically placed on one of these surfaces.

The combination of neutral species adsorption and positive ion bombardment results in surface chemical reaction. If the products of the surface reaction are volatile, they leave the surface and etching results. If the products are involatile, a surface film grows.

The Von Hippel Award is especially significant to me for several reasons. The name Von Hippel is legendary in the halls of Building 13 at the Massachusetts Institute of Technology, where I have worked for the last 12 years. Professor Von Hippel was one of the first to appreciate the interdisciplinary nature of materials research and engineering, and his insulation laboratory at MIT provided an early prototype for the National Science Foundation-supported system of interdisciplinary materials research laboratories in existence today. These laboratories, both at MIT and earlier at Cornell, have helped me in my research in many ways over the years.

Also I have been a recent councillor of the Materials Research Society and have been privileged to witness the phenomenal growth of MRS at first hand. The stature of the Von Hippel Award must be increasing at least in proportion to this growth. I, therefore, feel very honored and grateful indeed! I would also like to add that much of my work has been done in collaboration with valued colleagues and students. They deserve a substantial share of this award.

Over the years, my research has been devoted mainly to the experimental study of crystal defects and their behavior. These defects can be classified according to their dimensionality as shown in the accompanying table, and they are involved in one way, or another, with a host of phenomena in crystalline materials. Since I address a rather diverse audience, it might be appropriate to discuss some of the history of lattice vacancy research and some of the details of my personal contribution to it.