Plasma cleaning

If the gas used is oxygen, the plasma is an effective, economical, environmentally safe method for critical cleaning.

If the part consists of easily oxidized materials such as silver or copper, the treatment uses inert gases such as argon or helium instead.

[3] If a surface to be treated is coated with a patterned conductive layer (metal, ITO), treatment by direct contact with plasma (capable for contraction to microarcs) could be destructive.

[4] Results of the same applications to surfaces of glass samples coated with Cr and ITO layers are shown in Fig.

[5] Plasma cleaning removes organics contamination through chemical reaction or physical ablation of hydrocarbons on treated surfaces.

[3] Chemically reactive process gases (air, oxygen) react with hydrocarbon monolayers to form gaseous products that are swept away by the continuous gas flow in the plasma cleaner chamber.

[8] Plasma is often used as a chemical free means of adding biologically relevant functional groups (carbonyl, carboxyl, hydroxyl, amine, etc) to material surfaces.

[9] As a result, plasma cleaning improves material biocompatibility or bioactivity and removes contaminating proteins and microbes.

Plasma cleaners are a general tool in the life sciences, being used to activate surfaces for cell culture,[10] tissue engineering,[11] implants and more.

Increased surface hydrophilicity (wetting) following plasma treatment improves adhesion with aqueous coatings, adhesives, inks and epoxies: The unique characteristics of micro or nanoscale fluid flow are harnessed by microfluidic devices for a wide variety of research applications.

Fig. 1. The surface of a MEMS device is cleaned with bright, blue oxygen plasma in a plasma etcher to rid it of carbon contaminants. (100mTorr, 50W RF)
Fig. 2. Content of carbon over material depth z: before a sample treatment - diamond points and after the treatment during 1 s. - square points
Fig. 3. Contact Angle of Water Droplet of 5 μ l on glass coated with different materials.
Fig. 4. Surface area of water droplet of 5 μl volume footprint on glass surface versus time t after its treatment. Droplet on untreated glass is shown in inset.
Fig. 5. Plasma beam cleaning a metal surface