has been pioneering the development of devices fabricated to submicron tolerances for well over 20 years. In 1961, a landmark paper on electron-beam lithography and its associated technologies was published by K. R. Shoulderst (then at SRI), which set the stage for our subsequent efforts in this field. He had the foresight to believe that the building of such small devices was actually within the range of human capabilities. As a result of this initial momentum, our experience in the technologies associated with microfabrication has become remarkably comprehensive, despite the relatively small size of our research activity. We have frequently been asked to deliver seminars or provide reviews on various aspects of microfabrication. These activities made us aware of the need for a comprehensive overview of the physics of microfabrication. We hope that this book will fill that need. While there is a 'special emphasis on silicon microcircuit technology, this book is intended as an introduction for all engineers, scientists, and graduate students who are considering making something very small. The book may also serve as a source of review material for experienced workers in this extensive field, although no specialty is treated exhaustively. Though we have no desire to overlook anyone's contribution, we recognize that we may have failed to reference works or papers of significance. Any oversight is unintentional, and we would be pleased to receive suggestions for the improvement of any of the topics discussed. tMicroelectronics using electron beam activated machining techniques, Advances in Computers, 2, pp. 137-289, edited by F. L.

An electron beam projected onto a clean glass surface in vacuum is blown up by deceleration caused by the high surface charge accumulated, thus spreading the beam on a very short time scale before arrival on the surface. Arriving at the surface, electrons are rapidly bound to lattice imperfections (not adsorbed gas atoms) presumably creating O− ions. Thereupon, spread of the charge along and through the surface, progresses by movement of labile alkali ions which combine with the surface O− ions, leaving their initial negative O− partners behind in the glass. The rapid transfer of the negative charge from the surface to the interior of the glass, where it encounters dielectric screening, causes a temporary positive displacement current which masks the displacement current due to the discharge movement to the grounded electrode. It has a maximum value immediately following the electron beam cutoff, and declines approximately exponentially with a time constant τ, of about 0.1 sec for the range of electron surface charge densities, computed from beam cross sections ranging from 1010−3×1011 electrons/cm2. Thereafter, the charge leaks off as a volume conduction current on a time scale of tens of minutes. There is no surface conduction by free electrons, and surface conductivity of clean glass is low and comparable with volume conductivity. High apparent plasma induced surface conductivity lies in the plasma, and not in the glass.

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