Silicon wafer

A silicon wafer is a thin, round disc of single-crystal silicon, polished on one side until it's flatter and smoother than almost anything else people make. It's the canvas for chips: hundreds are built side by side on each wafer, then cut apart.

Wafers are cut from a silicon ingot. First, the ingot is ground to an exact diameter and a small notch is cut along its length to mark the direction of the crystal. Then a wire saw slices it. A single thin steel wire, wound back and forth into hundreds of parallel strands, runs fast through the ingot carrying abrasive grit, cutting many wafers at once. The rough slices are lapped flat, their edges are rounded, and damaged surface layers are etched away with chemicals. Finally, chemical-mechanical polishing gives a mirror finish, with height differences of only nanometers. The wafers are cleaned, inspected and sealed in clean boxes.

A standard 300 mm wafer is about 0.775 mm thick, enough to survive hundreds of process steps. Building circuits into its surface turns it into doped silicon and, eventually, the dies inside every chip in the TV.