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Anti-reflective coating
A anti-reflective coating is deposited on the top side to help
transmit more of the incident sunlight
Because the top side conductor has been already
fabricated and only low temperature process can be used, the typical process to
deposit anti-reflective coating is PECVD
PECVD• Plasma
• Enhanced
• Chemical
• Vapor
• Deposition
PECVD is used extensively in the manufacture of microelectronic devices because it allows for lower temperature processes
Just like in sputtering, a plasma is formed in an electric
field
The plasma allows for the deposition or growth of films at lower temperature than would
normally be required in just a CVD process
Trion ORION III PECVD tool
Typical PECVD Process• The wafer is loaded in into the vacuum
chamber
• The chamber is pumped to vacuum conditions
• The wafer is heated to deposition temperatures (300oC typical)
• Gas are introduced that will acts as precursors to the film growth
Typical PECVD Process (continued)
• Chamber pressure is regulated to provide an equilibrium pressure ( gas in, pumping out)
• RF power is applied to the chamber creating a plasma
• A film is grown based on the gases introduced
For our solar cell
• We will be using SiO2 as the antireflective coating
• There are better anti-reflective coatings but not available in the Cameron clean room such as SiN or ITO
Trion ORION III PECVDChamber lid open
Heated substrate stageCan accommodate up to 8”
wafers
Trion ORION III water chiller and dry (no oil) chemical vacuum pump
Trion ORION III process gas cabinet TEOS (tetraethylorthosilicon) SiO2 precursor
The blue tint to the solar cell is the anti-reflective coating
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