POST DRY-ETCH CLEANING METHOD FOR RESTORING WAFER PROPERTIES

A post dry etching process for restoring wafers damaged by dry etching such as RIE, comprising the steps of removing any dry etch residue layer from the etched portions of the wafer and forming an oxide on those etched portions; rapid thermal annealing the wafer to drive the oxygen from the oxide layer down into the wafer by a small amount, to getter impurities to this oxide layer, and to restore crystallinity below the oxide layer; and removing the oxide layer via an HF bath or a low power dry etch process. This is clearly demonstrated in the attached drawing which is a plot of the delta measurement in the ellipsometry calulcation versus photon energy, where it can be readily seen from curve 100 that the use of the full process sequence of steps including the oxide removal step as the last step in the sequence essentially restores the delta measurement for the RIE-exposed wafers to a close approximation of the delta measurements for the control wafers.