ENVIRONMENTALLY BENIGN VACUUM DEPOSITION WITH AIR-TO-VACUUM-TO-AIR TECHNOLOGY

The deposition of thin films and coatings frequently results in the ge neration of toxic waste, volatile organic compounds, or large amounts of waste water and sludge. Vapor deposition in vacuum offers a more en vironmentally benign alternative, but is not prevalent outside of the microelectronics industry due to economic reasons. However, vacuum coa ting could be more widely accepted, and could potentially replace nonv acuum deposition methods, if either the cycle time or costs associated with vacuum coating were reduced. In order to reduce the cycle time f or vacuum deposition, a robust system for continuous air-to-vacuum-to- air (AVA) transportation of discreet substrates has been developed and constructed in this study. This technology allows the insertion of di screte components into vacuum at high rates, without the need for vent ing the deposition chamber. Substrates have been repeatedly transporte d from atmosphere to 10(-5) Torr in under a second. The capability of the AVA technology was studied through the deposition and characteriza tion of CdS and CdTe films and photovoltaic devices. With the AVA tech nology, the need for venting the vacuum chamber to insert the substrat es and subsequent pumping of the system for deposition is eliminated. The AVA technology could be applied to the processing of silicon wafer s, compact disks, optical components, solar cells, cutting tools, and fasteners.