The use of plasma is an effective way to clean without using hazardous solvents. Plasma is an ionized gas capable of conducting electricity and absorbing energy from an electrical supply. Manmade plasma is generally created in a low-pressure environment. (Lightning and the Aurora Borealis are naturally occurring examples of plasma.) When a gas absorbs electrical energy, its temperature increases causing the ions to vibrate faster and “scrub” a surface. In semiconductor processing, plasma cleaning is commonly used to prepare a wafer surface prior to wire bonding. Removing contamination (flux) strengthens the bond adhesion, which helps extend device reliability and longevity. In biomedical applications, plasma cleaning is useful for achieving compatibility between synthetic biomaterials and natural tissues. Surface modification minimizes adverse reactions such as inflammation, infection, and thrombosis formation.
Plasma cleaning is a need in todays's microelectronics manufacturing as minute oxidation or contamination to the bond pads can reduce the adhesiveness of the bonds and induced reliability concerns.
Today's plasma machine has employed simple capacitor coupled parallel plate approach to maximize and have a more uniform plasma effect. For special cleaning, gases are mixed during the plasma clean and then mixture are then vacuum out with the contaminants.
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