I made an enclosure for the tube furnace and hooked it up to an arduino and solid state relay. The main body of the furnace is 5″x5″x12″ and filled with alumina ceramic wool. Impressively, the exterior only reaches 100°-200°C at most even while the tube inside is over 1000°C! That should keep the furnace from being a severe fire or burn hazard. Now I just need to write a PID loop with a proper temperature ramp controller and I should be good to go!
To make semiconductors, you need the capability of reaching very high temperatures, usually around 1000 degrees Celsius! This is well beyond the range of most household devices, so my toaster oven isn’t going to cut it. Semiconductor labs usually use a special kind of furnace called a tube furnace. The tube furnace is simply a quartz glass tube surrounded by a heating element and insulation. I bought a quartz tube from McMaster-Carr for $20 and wound some 22g nichrome wire around it and insulated the whole thing with some alumina ceramic wool and hooked it up to a variac as a proof-of-concept. I was able to reach 1000°C with only about 300W of power, which was actually a lot lower than I expected. Now I just need to put this in a proper enclosure, write some code, and I should be good to go! (famous last words!)