Wafer positioning

In semiconductor manufacturing, microlithography is used to transfer the pattern of circuitry from a photomask - a quartz plate containing the master copy of a microscopic IC - to a wafer on which the ICs are made.

To allow a reliable and effective production the individual wafers have to be positioned with a very high precision. Complex light guides are used for this purpose to transport monochromatic laser light to markers on the wafers. The diffracted light is then detected and transported with the help of other light guides to an analysis system, allowing a real time control of the manufacturing process.