Comparison of Cu thin films deposited on Si substrates with different surfaces and temperatures

Deposition and growth of Cu thin films on Si(1 0 0), Si(1 1 0) and Si(1 1 1) substrates are studied using molecular dynamics method. The Cu/Si interface diffusion, surface roughness, crystalline structure and growth orientation of Cu thin films are investigated in detail. The effects of substrate surface and temperature are analyzed. Our simulation results show that the number of Cu atoms getting across the substrate surface for Si(1 1 1) substrate is the largest, and the number for Si(1 1 0) substrate is the smallest. This is caused by the difference of the linear atomic densities and planar atomic densities of Si crystal in different directions and planes. The growth of Cu thin films deposited on Si(1 0 0) substrate is (1 0 0) oriented at low temperature, and gradually changes to be (1 1 1) oriented as the increasing of substrate temperature. On the other side, the growth of Cu thin films deposited on Si(1 1 0) and Si(1 1 1) substrates is always (1 1 1) oriented. Increasing substrate temperature could effectively reduce surface roughness, increase the number of Cu atoms with face-centered cubic (fcc) structure, but meanwhile increase the Cu/Si interface diffusion. Under the same substrate temperature condition, the number of Cu atoms with fcc structure in thin films deposited on Si(1 1 0) substrate is larger than that deposited on Si(1 1 1) substrate.