Effect of incident angle on the microstructure proprieties of Cu thin film deposited on Si (001) substrate

摘要

The deposition processes of Cu atoms onto Si substrate are studied in atomic-scale molecular dynamics (MD) simulation. Our aim here is to check how the microstructure properties of Cu thin film are affected by the incident angles. To this end, we have adopted various analytical techniques such as surface roughness, layer coverage, film density, and internal stress. Our results show that at low incident angles (0 degrees - 45 degrees), the deposition of Cu atoms on the substrate generates a compact and uniform thin film with approximately a smooth surface. However, at higher incident angles (60 degrees-85 degrees) the effects become more pronounced, where the thin film morphology is changed from a dense structure to a columnar structure with more voids and vacancies. The surface roughness was also significantly increased as the incident angle increases. On the other hand, the analysis of interface mixing revealed that there are little effects of the deposition angles on the film-substrate mixing, and the penetration of Cu atoms onto Si substrate is limited to the two first upper layers. In the same context, our calculations show that the film density decreases significantly along the growth direction when the incident angles are above 60 degrees. Finally, the result of residual stress after the deposition process demonstrates that the film has compressive stress at low incident angles, but it changed to tensile stress when deposition angles exceed 60 degrees.