Wafer prober

A wafer prober is a machine used to test integrated circuits.

Overview

Integrated circuits are fabricated in large numbers by a complex series of printing steps on silicon wafers. This process permits integrated circuits to be produced cheaply but each chip must be tested prior to its separation from the wafer (using a process known as wafer dicing). The testing of the wafer in this process is also known as wafer sort.

For electrical testing a set of microscopic contacts or probes called a Probe card are held in place whilst the wafer, vacuum-mounted on a Wafer Chuck, is moved into electrical contact. When a die (or array of dice) have been electrically tested the prober moves the wafer to the next die (or array) and the next test can start. The Wafer Prober is usually responsible for loading and unloading the wafers from their carrier (or cassette) and is equipped with automatic pattern recognition optics capable of aligning the wafer with sufficient accuracy to ensure accurate registration between the contact pads on the wafer and the tips of the probes.