The fabrication process is applied to thin
wafers of silicon. There are eight basic steps.
Some of these steps are repeated many times
making the total number of steps one hundred
or more. The entire process usually takes from
10 to 30 days. The eight basic steps are:
• Deposition (forming an insulating layer
of SiO2 on the silicon wafer)
• Photolithography (light-sensitive layer
exposed through a patterned photomask)
• Etching (removal of patterned areas using plasma gas or chemicals)
• Doping (placing donor and acceptor impurities into the wafer by diffusion or by
using ion implantation)
• Metallization (formation of interconnects
and connection pads by depositing metal)
• Passivation (application of a protective
layer)
• Testing (probes check each circuit for
proper electrical function)
• Packaging (wafers are separated into
chips, the chips are mounted, bonded/
wired, and the packages are sealed)