Design and Fabrication of VLSI Devices

Abstract

VLSI chips are manufactured in fabrication facility usually referred to as a “fab”. A fab is a collection of manufacturing facilities and “clean rooms”, where wafers are processed through a variety of cutting, sizing, polishing, deposition, etching and cleaning operations. Clean room is a term used to describe a closed environment where air quality must be strictly regulated. The number and size of dust particles allowed per unit volume is specified by the classification standard of the clean room. Usually space-suit like overalls and other dress gear is required for humans so that they do not contaminate the clean room. The cleanliness of air in a fab is a critical factor, since dust particle cause major damage to the chips and thereby determine the overall yield of the fabrication process. The key factor which describes the fab in terms of technology is minimum feature size it is capable of manufacturing. For example, a fab which runs a 0.35 micron fabrication process is simply referred to as a 0.35 micron fab.