Basic Resistor Layout

Let's follow the manufacturing process involved in making a polysilicon resistor, in order to understand all the components.

The substrate material is the bottom layer of raw silicon. On the substrate, we deposit a poly layer, which we will use to resist electrical flow.

Figure 4-12: Polysilicon layer.

We need to connect our bits of poly material somehow into the path of electrical flow. So, on top of the poly layer we lay down an oxide layer. This good insulator will protect further layers from contacting the poly in unwanted places.

Figure 4-13: Layer of oxide covers the poly layer.

Then we can etch through the oxide, making contact holes. These holes dig through to the poly in exact locations just where we want to make contact with the poly. Hence the name contact holes.

Figure 4-14: Holes cut through the oxide to expose the poly.

We deposit some metal into these etched holes. The metal fills the contact hole, contacting the poly. In the diagram, you will notice one etched contact hole at one end of the poly...