Making A Silicon Wafer

The silicon ingot is still not suitable semiconductor due to its polycrystalline structure. In order for the silicon to become a semiconductor it must be made into one regular structured crystal.

It is done by melting the silicon in a quartz crucible which rotates and is heated to 1414 °C.

A seed crystal of silicon is lowered into the crucible rotating in the opposite direction of the crucible. The seed cause the molten silicon to crystallize around it the crystal is slowly removed from the crucible. The rod which has formed is called boule. This process is called Czochralski.

Next the boule is cut into thin discs which are called wafers. The boule is cut with a wire saw. A 300mm diameter wafer is cut 0.775mm thick. Next the wafers are polished by lapping to be flat with in 2μm. Then is etched in nitric hydrofluoric and acetic acids. The nitric acid gives the wafer a layer of silicon dioxide which the hydrofluoric acid dissolve to leave a clean surface the acetic controls the reaction.

I referenced

Intel Museum website

https://www-ssl.intel.com/content/www/us/en/history/museum-transistors-to-transformations-brochure.html

Tech Radar

http://www.techradar.com/news/computing-components/processors/how-sand-is-transformed-into-silicon-chips-599785

Wikipedia for pictures

https://en.wikipedia.org/wiki/Wafer_(electronics)

https://en.wikipedia.org/wiki/Monocrystalline_silicon

Youtube video on Czochralski