Abstract: A system for reducing the concentration of foreign material on a wafer etched in a reactive ion etch chamber is disclosed. As a radio frequency voltage is applied within the etch chamber, the pressure within the etch chamber may be reduced to a base pressure. Also, the flow of gas into the etch chamber may be maintained. This may include minimizing the flow of high reactive gas into the etch chamber while maintaining the flow of low reactive gas therein. The system further includes deactivating the radio frequency voltage. Deactivating the radio frequency voltage may be accomplished by gradually reducing the voltage to a minimum voltage. The gradual reduction may be accomplished by incrementally reducing the voltage in a series of steps. If reactive ion etching occurs with magnetic enhancements, the magnetic field applied to the etch chamber may be deactivated, typically prior to the reduction of the radio frequency voltage.

Abstract: A flange hanger adapted for use in conjunction with a steel frame building for connecting spanner bars used in the "HAMBRO" floor system is formed with an elongated shape having a first flange for welding to a steel frame member of the building and a second flange adapted to depend vertically from the welded flange. The second flange is provided with a plurality of horizontally elongated slots to receive the ends of spanner bars and provide horizontal and vertical support therefor.