Multiple Automatic Retractable Distribution Shields
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
High rates of source material (Pn/Sn) evaporation are necessary to obtain uniform deposits of thick film (N5 mils). This may be accomplished by the use of a single, fixed distribution shield for Pb deposition, followed by Sn deposition from a second source. Poor Sn deposition uniformity may result, however, when evaporating Sn past a distribution shield designed for Pb evaporation, making it desirable that this shield be removed during the Sn evaporation cycle, particularly when evaporating on large wafer domes over extended throw distances. This disclosure concerns the installation of separate retractable distribution shields, automatically operated under microprocessor control, thereby assuring that each material to be evaporated be handled under optimal distribution shield positioning.