IC Knowledge - Glossary

Glossary of Integrated Circuit Terminology - W

Wafer - a round disc of semiconductor material most commonly Silicon, although Gallium Arsenide and other semiconductor materials are also used. Wafers are a few millimeters thick and are available in a variety of diameters with 100 millimeter, 125 millimeter, 150 millimeter and 200 millimeter being the most common and 300 millimeter just entering use. Many Integrated Circuits are simultaneously fabricated on wafers during the wafer fabrication process.
Wafer Fab - abbreviation for Wafer Fabrication Facility.
Wafer Fabrication - the process of creating integrated circuits on the surface of wafers.
Wafer Fabrication Facility (Wafer Fab or Fab)- a facility where the wafer fabrication process is performed. Fabs include a high quality cleanroom as well as support systems such as ultrapure water, gas and chemical generation and delivery systems, waste water treatment, extension HVAC equipment, as well as other support functions.
Wafer Probe - the test step where each individual die on a wafer surface is tested and bad die are marked as bad. Also called wafer test or wafer sort.
Wafer Size - the diameter of a wafer. Wafer sizes for 2 inch and 3 inch wafers were in inches, wafer sizes for all larger wafer diameters are in millimeters. Many people refer to a 4, 5, 6, 8 or 12 inch wafers, but it in fact a "4 inch wafer" is 100 millimeters , 3.937 inches.
Wafer Sort - see Wafer Probe.
Wafer Test - see Wafer Probe.
Wafer Yield - the number of wafers completed through the wafer fabrication process, divided by the numbers of wafers started into the wafer fabrication process, multiplied by 100. Sometimes referred to as line yield.
Wavelength - the length of one complete cycle of a wave. In semiconductors, wavelength is typically applied to light.
Wedge Bond - a type of wirebond where the wire end attachment looks like a wedge.
Well - a relatively deep, doped area in which devices are fabricated. CMOS requires at least one well because NMOS requires a P background doping and PMOS requires an N background doping.
Wetting - the degree to wich a liquid maintains contact with a surface. Poor wetting is indicated by liquids beeding up on a surface and good wetting is indicated by a continuous sheet of liquid forming on the surface.
WIP - see Work In Process.
Wirebond - the process where tiny wires are connected from chip bond pads to the leadframe.
Work In Process - the work undergoing a manufacturing process, for example, wafers in a Fab or die during packaging.
Working Plate - when contact printing was in use, masks wore out or became contaminated from direct wafer contact. Working plates are copies of an original or master plate. Many working plate copies of a master plate can be made before a new master plate needs to be generated. Working plates are less expensive than a master plate.