title: Large O2Cluster Ions as Sputter Beam for ToF-SIMS Depth Profiling of Alkali Metals in Thin SiO2Films.
abstract: A sputter beam, consisting of large O2clusters, was used to record depth profiles of alkali metal ions (Me+) within thin SiO2layers. The O2gas cluster ion beam (O2-GCIB) exhibits an erosion rate comparable to the frequently used O2+projectiles. However, because of its high sputter yield the necessary beam current is considerably lower (factor 50), resulting in a decreased amount of excess charges at the SiO2surface. Hence, a reduced electric field is obtained within the remaining dielectric layer. This drastically mitigates the Me+migration artifact, commonly observed in depth profiles of various dielectric materials, if analyzed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) in dual beam mode. It is shown, that the application of O2-GCIB results in a negligible residual ion migration for Na+and K+. This enables artifact-free depth profiling with high sensitivity and low operational effort. Furthermore, insight into the migration behavior of Me+during O2+sputtering is given by switching the sputter beam from O2+to O2clusters and vice versa. K+is found to be transported through the SiO2layer only within the proceeding sputter front. For Na+a steadily increasing fraction is observed, which migrates through the unaffected SiO2layer toward the adjacent Si/SiO2interface.
authors.affiliation: Infineon Technologies Austria AG , Siemensstraße 2, 9500 Villach, Austria.|Vienna University of Technology , Institute of Chemical Technologies and Analytics, Getreidemarkt 9, 1060 Vienna, Austria.
authors.forename: Sabine
authors.initials: S
authors.lastname: Holzer
authors.affiliation: Infineon Technologies Austria AG , Siemensstraße 2, 9500 Villach, Austria.
authors.forename: Stefan
authors.identifier: 0000-0002-1181-6510
authors.initials: S
authors.lastname: Krivec
authors.affiliation: ION-TOF GmbH , Heisenbergstraße 15, 48149 Münster, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Kayser
authors.affiliation: ION-TOF GmbH , Heisenbergstraße 15, 48149 Münster, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Zakel
authors.affiliation: Vienna University of Technology , Institute of Chemical Technologies and Analytics, Getreidemarkt 9, 1060 Vienna, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Hutter