Plasma etching in closed reactor - where air lock chamber precludes entry of damp air into reactor, esp. when etching semiconductor devices

摘要

No water or moisture is allowed to enter the reactor, pref. by using an air lock chamber so that atmos. air contg. moisture cannot enter the reactor. The air lock chamber is pref. evacuated and/or scrubbed with dry nitrogen prior to each etching cycle. Alternatively, the air lock chamber may be continuously filled by a stream of dry nitrogen. The reactor is pref. used for etching Al layers with a plasma contg. chlorine. Used esp. in mfg. semiconductor devices, where Al layers are dry etched in a high frequency field using a plasma gas at 0.1-1 torr. Only when all moisture is excluded from the reactor can constant etching rates be achieved. If moisture is present, it is adsorbed by the reaction prods., e.g. AlC13, and provides inconsistent etching speeds.