Big Improvements For Small Parts

摘要

Headquartered in Silicon Valley, CA, National Semiconductor Corp, supplies several companies with microcircuits, also known as microchips, which process massive amounts of signals into digital information., Microcircuits are inside all electronic devices, such as personal digital assistants, laptop computers and automotive controls They are made by processing wafers consisting mostly of silicon through many fabrication steps, such as oxidation and photomasking to define the circuit layout, and ion implantation and diffusion to define the transistor. When the wafers have completed the fabrication steps, they are diced into "chips," assembled into the final package and shipped to customers, who use them in assembling their end products. The fabrication process--from taw silicon to a packaged integrated circuit (1C)--involves more than 200 steps on 75 pieces of equipment. Processes involve epitaxial growth, ion implantation, photolithography, photomasking, diffusion, oxidation and chemical and physical vapor deposition. Many of these steps take place in class one clean rooms, meaning no more than one particle of dust greater than 0,5 micrometers is allowed per cubic foot of air.