title: pH-controlled selective etching of Al2O3 over ZnO.
abstract: We describe pH-controlled selective etching of atomic layer deposition (ALD) Al2O3 over ZnO. Film thickness as a function of etch exposure was measured by spectroscopic ellipsometry. We find that alkaline aqueous solutions with pH between about 9 and 12 will etch Al2O3 at useful rate with minimal attack of ZnO. Highly selective etching of Al2O3 over ZnO (selectivity >400:1) and an Al2O3 etch rate of ∼50 nm/min can be obtained using a pH 12 etch solution at 60 °C.
authors.affiliation: Center for Thin Film Devices and Materials Research Institute, ‡Department of Electrical Engineering, and §Department of Material Science Engineering, Penn State University , University Park, Pennsylvania 16802, United States.
authors.forename: Kaige G
authors.initials: KG
authors.lastname: Sun
authors.forename: Yuanyuan V
authors.initials: YV
authors.lastname: Li
authors.forename: David B
authors.initials: DB
authors.lastname: Saint John
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Jackson