Conductor-insulator-semiconductor structures for surface-charge transport

In order to advantageously exploit surface-charge transport of the type recently reported in practical devices, We have utlized a multilevel overlapping molybdenum metallization system. Specific structures will be presented that offer significant improvements in both speed and density over conventional MOSFET´s and practical limits will be discussed. These new structures and the processing that produces them are compatible with self-registered MOSFET transistors, so that logic and amplification functions as well as charge-transfer devices are available on the same chip. The mathematical theory of the motion for surface charge is derived and discussed. A key result is that, although the transport equation is a diffusion equation, the effective diffusion constant is several hundred times larger than the thermal diffusivity of the minority carriers. A solution of this equation for shift-register-type device structures and the results of some simple experiments verifying the solution will be presented, and implications for speed and efficiency of charge transfer will be discussed.