In the talk given in the Correlations forum at hfg Offenbach1, I passed around a piece of the wafer to the audience so they could actually see the materials in question. I acquired these wafers from eBay, which cost me around 5 EUR a piece. What struck me as particularly fascinating is how incredibly delicate they are. Since the material is in an ultra-purified state, even the slightest touch can grease and contaminate the surface, leaving a noticeable mark behind. After the talk, the piece is covered up with fingerprints from the audience. This sensitivity underscores a hint of how the manufacturer must be in a precise and controlled environment.
After quartz is purified into silicon, the next step is to form it into the wafers that will then be cut into slices that carries transistors. This domain of production is called wafer manufacturers; Shin-Etsu Handotai and SUMCO of Japan, along with Siltronic in Germany are the main suppliers in such productions. The process begins by melting chunks of purified silicon and dipping a seed crystal into the crucible. Through the Czochralski process, a large single-crystal ingot of silicon is slowly pulled out from the melt.
Once the ingot is formed, it will be sliced with a diamond-coated saw into a thin circular disc to ensure consistent thickness. These discs are then edge-rounded to eliminate sharp edges. Next, the wafer goes through lapping and etching to smooth the surface and remove any residual surface damage. Then, they are annealed, and heated in a controlled environment to relieve internal stresses and improve the crystal structure. Finally, these wafers are polished with chemicals to achieve an ultra-flat, mirror-like surface for semiconductor fabrication. All of these processes must be conducted in ultra-clean environments, often within cleanrooms, where the number of airborne particles is tightly controlled. Even a single speck of dust can render a wafer unusable.