Pumping chlorinated gases in plasma etching

Plasma etching of aluminum, aluminum alloys, and some other materials involves the use of chlorine‐based gases which are particularly corrosive to vacuum systems if precautions are not taken. Emphasizing safety concerns, we will demonstrate the proper use of cold traps, activated charcoal sorbent, and/or inert synthetic fluids to lubricate forepumps, enabling the user to deal with this corrosion problem. The sorption capacity of activated charcoal is discussed for the proper design of sorption traps, and methods of regenerating large cold traps saturated with hazardous products are examined. Information on the use of turbomolecular pumps in reactive ion etching is also given.