Aqueous hydrofluoric acid vapor processing of semiconductor wafers

摘要

Disclosed are methods and apparatuses for improved etching of semiconductor wafers and the like using hydrofluoric acid (HF) and water mixtures or solutions which generate equilibrium vapor mixtures of HF vapor and water vapor which serve as a homogenous etchant gas. The vapor etchants do not employ a carrier gas which will make the vapors nonhomogeneous and reduce etching rates. The vapors are preferably generated from a liquid source which is provided within a contained reaction chamber which holds the wafer. The wafer is preferably oriented with the surface being processed directed downward. The wafer is advantageously positioned above or in close proximity to the equilibrium liquid source of the vapor. The wafer is rotated at a rotational speed in the range of 20-1000 revolutions per minute to provide uniform dispersion of the homogeneous etchant gas across the wafer surface and to facilitate circulation and transfer from the liquid source into etchant gas and onto the processed surface. The liquid source of the vapor can advantageously be provided in a bath immediately below the processed surface of the wafer or in a toroidal basin adjacent to the wafer. The processes provide high speed etching of good uniformity and superior particle count performance.