Abstract
A study in a university setting was undertaken on the by-products which accumulated within a plasma etching reactor system from two years of sporadic dry etching of gallium arsenide wafers. The deposits on the reactor chamber walls, in the vacuum pump oil and its filter, in the oil mist eliminator, and in the exhaust charcoal canister were analyzed for 33 elements by simultaneous inductively coupled plasma atomic emission spectroscopy. A mass balance showed that gallium and arsenic have separate accumulation points. Gallium residues were detected only on the wall of the reactor chamber. Most of the arsenic residues were found in the rotary pump oil. The large amount of inorganic chloride in the charcoal filter indicates a potential emission of volatile chlorine-containing compounds, such as HCI and volatile metal chlorides. Arsenic was not detected in the charcoal filter.