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AssigneeAllied Corporation
InventorsRonald J. Hopkins, Evan G. Thomas, Harold J. Kieta
Estimating the term…
Silicon trioxide etching solutions with soluble surfact additives are provided. The improved silicon dioxide etchants are produced by adding soluble perfluornated surfactant additives to standard oxide etchants in the manufacture of integrated circuits. These surfactant additives are unique because they remain dissolved in the oxide etchant (ammonium fluoride/hydrofluoric acid mixture) even after 0.2 micron filtration. In addition, the filtered solutions retain their surface active properties and are low in metallic ion impurities. The surfactant additives provide etchant solutions with lower surface tensions, which improves substrate wetting and yields better etchant performance. The surfactant does not leave residues or adversely affect etchant profiles.
An etching solution containing a surfactant which is stable against precipitation of the surfactant comprising an aqueous mixture of ammonium fluoride and surfactant that contains between 13.5 and 45 weight percent ammonium fluoride (NH.sub.4 F) and between 25 and 20,000 ppm of a fluoroalkylsulfonate surfactant of the formula
The process for producing the etching solution which comprises blending 49% by weight aqueous hydrogen fluoride and a 15% to 40% by weight aqueous solution of ammonium fluoride, with 200 to 5000 ppm active fluoroalkylsulfonate surfactant.
Dependencies are inferred from the claim text.