One-Step Fabrication of Copper Thin Films on Insulators Using Supercritical Fluid Deposition

A one-step fabrication method for direct supercritical fluid deposition (SCFD) of Cu on insulators was developed. This overcomes the limitation of conventional SCFD, which cannot directly deposit Cu on insulators. In our one-step method, a relatively small amount of an Mn precursor was mixed with a Cu precursor to deposit a CuMn x O y composite layer on an insulative underlayer. This underlayer then acted as a buffer layer, allowing subsequent Cu deposition. This method successfully achieved Cu deposition on insulators, including SiO 2 , boron phosphorus silicon glass (BPSG), and Parylene. The superior conformal deposition ability of conventional SCFD was also demonstrated using our one-step method, where Cu was deposited uniformly on an overhung test structure. Detailed analysis revealed that our one-step method was initiated by deposition of MnO x , which could include Cu, resulting in CuMn x O y film formation, followed by Cu deposition. The amount of the MnO x deposited during Cu deposition was negligible due to the much lower growth rate of MnO x compared with Cu. This process is useful for the fabrication of electronic devices having complex features and comprising various materials.