Static Electrical Characteristics of MOSFET.pptVIP

Static Electrical Characteristics of MOSFET * * Professional English in Microelectronics Technology 6.1 * * Professional English in Microelectronics Technology In the last few years, the metal-oxide-semiconductor (MOS) transistor has emerged as the most important electronic device, superseding the bipolar junction transistor in sales volume and applications. Its strength derives form(from) its simple structure and low fabrication cost. For these reasons, the MOS transistor should continue to be the most popular device for very large scale integration and mass-production products. In this chapter, we discuss the basic operation of the most important class of FETs: the si-based insulated-gate field-effect transistor (IGFET). 6.1 * * Professional English in Microelectronics Technology The gate material in these devices was originally a metal (aluminum) and the insulator was silicon dioxide (SiO2). That is the origin of the term metal-oxide-semiconductor field-effect transistor, or MOSFET. For case of fabrication and reproducibility, however, the current practice is to use degenerately doped polycrystalline Si (poly Si), which is highly conductive, instead of metal for the gate. In n-channel devices, n+ poly-Si is used for the gates, and p+ poly-Si is used for p-channel devices. Silicon dioxide is still usually used for the insulator, although nitrogen is sometimes incorporated into the SiO2 to increase its dielectric constant. 6.1 * * Professional English in Microelectronics Technology While the term IGFET is a more accurate description, in this book we adopt the practice common in the industry, which is to use the more common term MOSFET to describe this class of devices. In this chapter, we discuss the MOSFET fundamentals involved in the static electrical characteristics. In next chapter, we will cover the short-channel effects important in modern MOSFET devices, the time-dependent characteristics, and in addition, we discuss the other types of field-effect transi