Diffusion is one of the most important and inevitable processes in the manufacturing. This process is based on putting a sample (in many cases silicon) in a quartz tube furnace, and increasing temperature up to 850 °C in a gas atmosphere containing Boron or Phosphorus atoms; During this process, by diffusion of phosphorus and boron, the lithographed areas turn into n-type and p-type silicon, respectively.
The high temperature furnace is used to create doping in the source and drain regions of the field-effect transistors. The maximum working temperature is 1200 °C, and the required dopants are phosphorus and boron. The precise control of gases, as well as developed process to create uniformly doped regions are of its privileges. The possibility of doping of boron and phosphorus with different doping percentages (from 1015 to 1019) and with high reproducibility is another feature of this device. The device temperature accuracy is 1 °C.