TABLE OF CONTENTS Doped regions and N-P junctions are the electronic hearts of the active components in a circuit. However it takes various other layers of semiconductors, dielectrics, and conductors to complete the components and facilitate the integration of the components into the circuit. These layers are added to the wafer surface by a number of techniques. The principle ones are chemical vapor deposition (CVD), physical vapor deposition (PCD), electroplating, spin-on, and evaporation. This chapter describes the most commonly used CVD techniques and dielectric and semiconductor materials deposited on the wafer surface. PVD, electroplating, spin-on, and evaporation processes are described in Chapter 13.
Upon completion of this chapter, you should be able to:
Name the parts of a CVD reactor.
Describe the principle of chemical vapor deposition.
List the conductor, semiconductor, and insulator materials deposited by CVD techniques.
Know the difference between atmospheric CVD, LPCVD, hot-wall, and cold-wall systems.
Explain the difference between epitaxial and polysilicon layers.
Advances in photomasking technology have allowed the fabrication of ever-smaller dimensioned ULSI circuits. But as the circuits have shrunk, they also have grown in the vertical direction through increased numbers of deposited layers. In the 1960s, bipolar devices had two layers deposited by chemical vapor deposition (CVD), an epitaxial layer, and a top-side passivation layer of silicon dioxide (Fig. 12.1), while early MOS devices had just a passivation layer (Fig. 12.2). By the 1990s, advanced devices featured four levels of metal interconnects, requiring numerous deposited layers (see...
