TABLE OF CONTENTS This chapter focuses on the fundamental aspects of metal-oxide semiconductor (MOS) device behavior that are of immediate relevance to practical integrated circuit (IC) design. It is intended as a review of basic principles rather than an in-depth treatment of advanced topics.
This chapter is organized as follows. Section 1.2 describes the fundamental aspects of MOS transistors. The basic properties of MOS switches are discussed in Section 1.3. The behavior of the MOS device as a capacitor is discussed in Section 1.4.
Perhaps the most widely adopted process technologies in today's IC industry are those that use metal-oxide semiconductor (MOS) transistors. A MOS transistor can also be referred to as a metal-oxide semiconductor field-effect transistor (MOSFET). Other acronyms are MOST (for MOS transistor) and IGFET (for insulated-gate field-effect transistor). The term metal in the acronym MOS indicates that the transistor's gate is made of metallic materials such as metalsilicon. Nowadays, heavily doped polycrystalline silicon (also known as polysilicon) is usually chosen over metalsilicon because polysilicon can be aligned and scaled with higher geometric precision, resulting in smaller and faster transistors.
There are two complementary types of MOS transistors: N-channel MOS (NMOS) and P-channel MOS (PMOS). NMOS transistors use electrons to deliver charge in the presence of a positive gate voltage, while PMOS transistors use holes (which are equivalent to positive carriers) to conduct current in the presence of a negative gate voltage. Be it of NMOS or of PMOS type,...
