| AVS 60th International Symposium and Exhibition | |
| Advanced Surface Engineering | Thursday Sessions |
| Session SE+NS+TF-ThA |
| Session: | Nanostructured Thin Films and Coatings |
| Presenter: | M. Mühlbacher, Montanuniversität Leoben, Austria |
| Authors: | M. Mühlbacher, Montanuniversität Leoben, Austria F. Mendez Martin, Montanuniversität Leoben, Austria B. Sartory, Materials Center Leoben Forschung GmbH, Austria J. Keckes, Montanuniversität Leoben, Austria J. Lu, Linköping University, Sweden L. Hultman, Linköping University, Sweden C. Mitterer, Montanuniversität Leoben, Austria |
| Correspondent: | Click to Email |
Interface-controlled materials are widely applied in microelectronics as thin conductive or isolating layers and as diffusion barriers. Degradation of such barrier layers by segregation or diffusion typically results in failure of the device. Thus, as the basis for further enhancement of their reliability, a fundamental understanding of diffusion in these interface-controlled layer materials is necessary.
The Cu/TiN thin film system investigated in the present study is of particular technological relevance, with Cu layers being used as interconnectors and TiN as a diffusion barrier material. TiN layers were grown on (001) oriented MgO substrates by unbalanced DC magnetron sputter deposition at a substrate temperature of 700°C in an Ar/N2 atmosphere. Subsequently, within the same deposition run, Cu top-layers were deposited at 50°C in pure Ar. To investigate the efficiency of the TiN barrier layer against in-diffusion of Cu, these bi-layer samples were then annealed in vacuum for 60 minutes at 600 and 900°C, respectively.
Pole figures and electron back-scatter diffraction orientation maps indicate that both layers in the as-deposited state are single-crystalline with a cube-on-cube epitaxial relationship with the substrate. This epitaxial relationship is confirmed by selected area electron diffraction patterns. The interfaces were studied on an atomic scale by a combination of high-resolution transmission electron microscopy (HRTEM) and laser-assisted three-dimensional atom probe tomography (3D-APT). HRTEM confirms the single-crystalline structure of each layer and atomically sharp interfaces between both Cu-TiN and TiN-MgO. 3D-APT and energy dispersive X-ray spectroscopy mappings were used to determine the elemental distribution over the interface in the as-deposited and annealed state, enabling to illuminate the inter-diffusion behavior.