Semiconducting materials have properties somewhere between those of a good conductor (like a metal such as copper or aluminum) and those of a good electrical insulator (dielectric) such as glass or plastic. Silicon is an elemental semiconductor and has two very useful material properties that have led to it dominant role in electronic manufacturing. The first is that oxidizing silicon produces a glass insulating layer on the surface. Not only is the layer insulating but it is very stable and inert, it can be patterned and etched in small regions and can block chemical penetration in other regions. The other useful property is that the conductivity of the silicon can be changed in certain regions buy the introduction into the silicon of other elements from the periodic table like boron and phosphorous.
The chemical reaction used to form silicon dioxide (glass) or to introduce elements by diffusion requires elevated temperatures (>800C) in order to have a layers that are thousands of Angstroms thick in a reasonable time (hours).
Diffusion is the movement of material from areas of high concentration to areas of low concentration over a period of time. In a home plug-in room deodorizer, a liquid fragrance source is heated and gas molecules are dispersed by diffusion throughout the room. We use a very sophisticated computer controlled furnace system to reliably create the desired layers on our silicon wafers.
Insert pictures of an air freshener and our diffusion furnace.
Our classes and labs are unique and use the SMFL equipment for undergraduate and graduate education as well as undergraduate and graduate research projects.
Courses using Oxidation and Diffusion include:
To view the detailed equipment links visit the SMFL site: http://www.smfl.rit.edu/
Safety in the SMFL is essential for all users and enables research as well as education of undergraduate and graduate students.