TABLE OF CONTENTS In our gradual development toward the MOS transistor, we consider in this chapter the two-terminal MOS structure. This structure is often referred to as MOS capacitor and is shown in Fig. 2.1. The acronym MOS, standing for metal-oxide-semiconductor, is used independently of whether the gate is actually made of metal or whether the insulator is silicon dioxide. In the days when gates were made of metal, it became common to use the term semiconductor to refer unambiguously to the substrate material. Such usage continues today, even though the gate is normally made of polysilicon.
The two-terminal MOS structure has been the subject of extensive studies over many years. Such studies have resulted in a detailed understanding of the structure and identified the sources of a number of undesirable effects that plagued early work. This led to the development of better fabrication methods which greatly reduced such effects and which made possible MOS transistors with high performance. A detailed study of the two-terminal MOS structure and a related history can be found else-where. [1] Here we will only discuss those aspects directly relevant to the objective of this book. We will consider the various potentials and charges developed in the two-terminal MOS structure (assumed made with a modern fabrication process) when a voltage is applied between gate and substrate. We will also consider the capacitance properties of the structure.
Most of the foundation for our later study of the...
