Dual-tank etch method for oxide thickness control

摘要

A dual-tank etch method which is suitable for the stripping of a silicon nitride layer from a pad oxide layer provided on a substrate, and etching of the pad oxide layer to a desired target thickness, is disclosed. The method includes providing a first processing tank containing a silicon nitride-stripping chemical; stripping the silicon nitride layer from the pad oxide layer by placing the substrate in the first processing tank; providing a second processing tank containing an oxide-etching chemical; and etching the pad oxide layer to the desired target thickness by placing the substrate in the second processing tank. By carrying out the pad oxide-etching step and the silicon nitride-stripping step in separate processing tanks, accumulation of silicon oxide precipitates in the second processing tank is avoided.