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Abstract

Gas discharge apparatus comprising an annular gas-emitting electrode for use with wafer etching systems, and the like. The gas discharge apparatus comprises a housing and an annular electrode having provisions for cooling the electrode having predetermined outer and inner diameters secured to the housing. An inert outer chimney is disposed against a face of the annular electrode adjacent its outer diameter and an inert inner chimney is disposed against the face of the annular electrode adjacent its inner diameter. The inner and outer chimneys confine the gas discharge from the annular electrode to its face. An insulator is secured to the housing that has an opening that permits the flow of etching gas therethrough to produce a radially symmetric flow pattern. The insulator is disposed within the inner chimney and is centered relative to the annular electrode. The nonconducting components of the gas discharge apparatus are typically made of inert materials such as MACOR.RTM. ceramic, magnesium oxide, and magnesium fluoride, for example. The housing may be made of aluminum so that it can be water cooled, for example, to remove heat from the annular electrode during etching, or the electrode may be directly cooled. The gas discharge apparatus introduces the gas at the center of the annular electrode without causing any secondary discharge. Consequently, sufficiently high etch rates are achieved. The annular electrode does not exhibit erosion effects at very high power and very high gas flow rates. The annular electrode provides a removal profile with a relatively high spatial frequency which provides for a finer scale of correction of wafer surfaces.

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First Claim