Semiconductor Basics

10Integrated Circuit Fabrication

OBJECTIVES OF THIS CHAPTER

We now understand the physics and some of the uses of the most common semiconductor electronic components. It is time to see how we make them. The methodology of how semiconductor devices are made is quite simple and is basically the same as was used 60 years ago. Sure, the technology has improved by factor of millions and the equipment used is so sophisticated that one piece of equipment can cost a billion dollars, but what these sophisticated machines do is quite easy to understand.

In this chapter we are going to look at all the processing steps that we use to make semiconductor devices. You will see that the process is a repetition of a number of steps. As I discuss different processes, I will exemplify them by showing step by step how we fabricate a simple transistor (Sections 10.5 and 10.7). Believe me, the circuits can be very complicated but the steps to get there are the same (almost) as those used to fabricate a single transistor. I recommend you go to the inserts with the color figures to better understand the process.

10.1 The Basic Material

The basic material to obtain electronic quality silicon is sand or silicon dioxide. With a variety of chemical reactions and high‐temperature treatments, converting silicon first into a high‐purity gas and then solidifying again, we are able to remove many of the impurities (primarily iron and aluminum). Because these impurities or impurity compounds have different ...