Journal of Vacuum Science & Technology B, Vol.18, No.3, 1369-1374, 2000
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 obtained during secondary ion mass spectrometry analyses of polycrystalline-TiN/Ti/TiN(001) trilayers using a Cs+ ion beam. The sputter-etching rate R and 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 between the incident beam and one of the in-plane [100] directions in TiN(001) is varied from 0 degrees to 40 degrees, R-TiN(001) varies by more than 40% and 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. Channeling of primary ions and secondary recoils through 0.106-nm-wide channels between highly aligned (100) or (010) planes in TiN(001). and the lack of such correlated long-range alignment in polycrystalline TiN, are the: major reasons fur the observed differences. Channeling in the TiN(001) layer results ill a sharp decrease of Y-Ti in the Ti layer immediately prior to the Ti/TiN(001) interface and increases the interface width, thus degrading depth resolution. These profile distortion effects: can be eliminated either by sample rotation during profiling or by using an O-2(+) primary beam.
Keywords:SAMPLE ROTATION