Channeling-induced asymmetric distortion of depth profiles from polycrystalline-TiN/Ti/TiN(001) trilayers during secondary ion mass spectrometry

Asymmetric depth profiles of elemental and molecular secondary ions are obt ained during secondary ion mass spectrometry analyses of polycrystalline-Ti N/Ti/TiN(001) trilayers using a Cs+ ion beam. The sputter-etching rate R an d the secondary ion yield Y from TiN(001) layers are strongly dependent on the incidence angle of the primary ion beam. When the azimuthal angle betwe en the incident beam and one of the in-plane [100] directions in TiN(001) i s varied from 0 degrees to 40 degrees, R-TiN(001) varies by more than 40% a nd Y-TiN(001) by nearly a factor of 3, In contrast, for polycrystalline TiN layers, R-polyTiN and Y-polyTiN are invariant With incident beam angle. Ch anneling of primary ions and secondary recoils through 0.106-nm-wide channe ls between highly aligned (100) or (010) planes in TiN(001). and the lack o f such correlated long-range alignment in polycrystalline TiN, are the: maj or reasons fur the observed differences. Channeling in the TiN(001) layer r esults ill a sharp decrease of Y-Ti in the Ti layer immediately prior to th e Ti/TiN(001) interface and increases the interface width, thus degrading d epth resolution. These profile distortion effects: can be eliminated either by sample rotation during profiling or by using an O-2(+) primary beam. (C ) 2000 American Vacuum Society. [S0734-211X(00)01503-1].