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A DIY tube furnace for creating ICs

Arduino TeamAugust 14th, 2023

Modern integrated circuit (IC) chips can have transistors as small as two nanometers, which is only about 10 silicon atoms laid end-to-end. At that scale, fabrication looks more like chemistry than any kind of physical manipulation — a machinist isn’t carving tiny transistors into silicon wafers. For many types semiconductors, the fabrication process requires a very powerful furnace. If you’re interested in creating your own ICs, then YouTuber ProjectsInFlight has a video explaining how to build your own furnace.

This is a design for a tube furnace that can reach 1200°C, similar to the kind that labs buy for many thousands of dollars. Producing that much heat in a controllable manner is not a trivial task and this is much more complicated than constructing a furnace for something like aluminum casting. The heating element is a coil of nichrome wire, which wraps around a quartz glass tube that can withstand the heat. A ridiculous amount of insulation surrounds the tube and wire to contain the heat.

Nichrome wire heats up through resistance when a current passes through, so you could just connect it to a power source. But that wouldn’t be controllable, so ProjectsInFlight created a control board based on an Arduino UNO Rev3 board. Like a 3D printer controller handling hot end temperature through proportional–integral–derivative (PID), this uses a closed-feedback PID loop to modulate power to the nichrome wire in response to readings from a thermocouple. The control interface has a dial for setting the target temperature and a 16×2 character LCD to show the current temperature detected by the thermocouple. The Arduino uses a solid-state relay (SSR) to modulate the power going through the nichrome wire.

A simple sheet metal enclosure houses the tube and, in a separate area, the control electronics. The furnace seems to be capable of safely reaching the desired temperature, so ProjectsInFlight can now use it for semiconductor experiments.