EE 432: Semi-Conductor Fabrication

summary

In this class we spent a semester learning and producing the steps needed to make microelectronic devices. This took place in an off-campus science lab. The devices created were crude, in other words, an array of resistors, capacitors, and other circuitry components. The process consisted of learning and applying semi-conductor physics and spending many hours in lab baking silicon wafers.

Each square seen on the wafer consisted of dozens of transistor logic devices.

Lab summary

Each lab consisted of new mathematical and physical concepts that aided in the creation of this silicon wafer (pictured left). We often used diffusion calculations and many others to decide how long we needed to bake the wafer, or how long to soak it in chemicals.

The final product was an array of squares that marked the areas for microelectronic devices. You may not be able to tell in this image, but each square picture has numerous microscopic circuit components etched onto them. It was fascinating to conduct the process in which most technology relies on today.

lab example

This page out of our lab manual shows an ideal day in our semi-conductor's life. You can see the filled in spaces denote our calculated times and temperatures to achieve the various depths of our junction for that day.

Below, there is an image of a side view of our devices. The layers can be seen above the metal surface after many oxidizations and diffusions. We checked the thicknesses with a light-beam machine each day to ensure accurate dpeths were being achieved.

In this image you can see a semi-conductor device under a microscope. The large pads acted as grounds or terminals in the PMOS device, while the green section separated the metals across the P-N junction. The semester was interesting and elaborate as far as learning the process of developing semi-conductor devices.

State of the art equipment from leading manufacturers can complete this process in a matter of hours, and on a scale of 1,000 and even 1,000,000 times smaller. Nonetheless, learning about semi-conductors and P-N Junctions is one thing, building one is another. It really put the process and physics into perspective.

learning outcomes

Semi-conductor transistor physics
Fabrication of semi-conductor silicon wafers
Advanced lab procedures

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