Wafering

Wafering is the industrial process of shaping bulk crystalline materials into thin, flat discs called wafers, used as substrates for semiconductor devices. The term is most often applied to silicon, but wafers are also made from germanium, gallium arsenide, silicon carbide, sapphire, and other materials.

Modern semiconductor fabs produce wafers in diameters ranging from a few inches to 300 mm (12 inches), with 200 mm and 300 mm being common in many production lines. Wafers are typically single crystals with defined lattice orientations (for example, 100 or 111 planes), which influence device fabrication and performance.

The process begins with crystal growth, using methods such as the Czochralski or float-zone technique to form a cylindrical ingot. The ingot is sliced into discs by high-precision wire sawing or diamond blade cutting. Edges are trimmed, and the wafers undergo grinding, chemical-mechanical polishing (CMP), and cleaning to achieve uniform thickness and an atom-smooth surface. Additional steps may include etching, oxide growth, and inspection.

Quality control focuses on thickness uniformity, bow and warp, surface roughness, subsurface damage, and particulate contamination. Wafers are sorted by diameter, thickness, and other properties before they enter downstream fabrication lines, where they serve as substrates for lithography and device construction.