Method for etching a dielectric layer over a semiconductor substrate

摘要

A wet etch bath (61) holds a wet etchant (52) for etching a dielectric over a semiconductor substrate. The wet etch bath (61) has a tub (63) separated from a reservoir (64) by a wall (65). The tub (63) is filled with the wet etchant (52) to a height of the wall (65). The reservoir (64) is filled with the wet etchant (52) to a height less than the height of the wall. A pump (66) coupled to the reservoir (64) pumps the wet etchant (52) through an osmotic membrane degasifier (69) to the tub (63). Adding the wet etchant (52) to the tub (63) causes the wet etchant (52) to cascade over the wall (65) back to the reservoir (64). The osmotic membrane degasifier (69) reduces a concentration of a reactive agent in the wet etchant (52).