Pulsed laser deposition and characterization of epitaxial Cu/TiN/Si(100) heterostructures

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Abstract
Three‐dimensional epitaxial Cu/TiN/Si(100) heterostructures have been grown by pulsed laser deposition using a single chamber, in situ processing method. The epitaxial TiN layers on Si(100) were grown at 600 °C and epitaxial Cu layers on TiN/Si(100) in the temperature range 200–600 °C using optimized laser parameters. These structures were characterized using three‐axis x‐ray diffraction (Θ, Φ, Ψ scans) technique and high‐resolution transmission electron microscopy. The results clearly indicate cube‐on‐cube epitaxial alignment along the three axes, i.e., 〈100〉Cu∥〈100〉TiN∥〈100〉Si. The Cu/TiN and TiN/Si interfaces were found to be quite sharp without any indication of interfacial reaction. The growth mechanism of copper on TiN was found to be three dimensional, with the size of island varying from 0.3 to 1.5 μm. We discuss domain matching epitaxy as a mechanism of growth in these large lattice mismatch systems, where three lattice constants of Si(5.43 Å) match with four of TiN(4.24 Å) and seven units of Cu(3.62 Å) match with six of the TiN. The implications of these results in the fabrication of advanced microelectronic devices are discussed.