Integrated Circuit Fabrication

This chapter looks at all the processing steps that we use to fabricate semiconductor devices and integrated circuits. It discusses different processes, and exemplifies them by showing step by step how we fabricate a simple transistor. A perfect silicon boule can be obtained by two techniques: the Czochralski method and the float-zone method. Once the boule is completed, we slice it into very thin wafers, about 1/32 of an inch thick. In most cases we want a more perfect material than the boules can provide and we want to introduce different dopings. Epitaxial layers are grown on top of the wafers to achieve this. The chapter discusses the process of photolithography and the fabrication of a pnp transistor on a silicon wafer as well as the ways we can locally change the electrical characteristic of the semiconductor by doping. Ultra clean rooms are essential to process integrated circuits.