Improvement of thermal stability of Cu/Cu(Zr)/p-SiOC:H film stack using an ultra-thin Zr(Ge) alloy film as an exhaustion interlayer

Nano-layered films of Cu/Cu(Zr)/Zr(Ge) and Cu/Cu(Zr) were deposited on the Si/SiOC:H substrates by magnetron sputtering. Samples were subsequently annealed at temperatures ranging from 350~500°C in vacuum, and characterized by four-point probe technique, glancing incident angle X-ray diffraction, Auger electron spectroscopy (AES) and transmission electron microscopy. The results indicated that the thermal stability of Cu/Cu(Zr)/Zr(Ge)/SiOC:H/Si structure was fairly good when an ultra-thin Zr(Ge) layer used as an interlayer material. Upon annealing at 450°C, a self-grown ZrOx/CuxGe layer formed at the interface between Cu(Zr) and SiOC:H. This self-grown layer strongly prevented Cu diffusion into SiOC:H and free Si atoms into Cu film. In contrast, the diffusion of Cu atoms into SiOC:H was apparent for Cu/Cu(Zr)/SiOC:H/Si structures at this temperature, even if the Zr content in the Cu(Zr) film is up to 25.6 at.%. In addition, the impacts of Zr(Ge) contents on the thermal stability of film stacks and the resistivity of the multilayered structure are also discussed.