Opening Thoughts on Wafer Processing

In the first chapter, we introduced an impurity into a silicon crystal to free some electrons. Then we sent those free electrons off to do work for us. These N Type and P Type materials were shown as regions that could be placed anywhere on a chip. Now it's time to learn how that placement happens.

In this chapter, we will see how chips are actually grown, slimed, blasted and gassed, depending on what we draw on our computer screens. We will build an IC from scratch to see how our drawings are used to create our product.

Starting with our substrate wafer, we can do three things: We can change it, add to it, or remove material from it. Once we understand how to make these changes, we will see how we can change, add or remove material from just the specific areas we want.

IC Layout

An IC is built sequentially in steps. The process steps work together to add layers to the IC. The chip gets thicker as the fabrication continues. Each step in the process has its own representative drawing. All these drawings relate to each other, forming three-dimensional components that operate together to form a working IC chip. IC layout is the process of creating the two-dimensional representations of the fabrication layers, which are then used to manufacture an IC chip.

When IC's were first being developed, the drawings were placed on clear plastic film using red see-through sticky...