Area-selective chemical vapor deposition of Co for Cu capping layer

Selective chemical vapor deposition (CVD) of Co on Cu interconnect lines is an advantageous method because it can simplify unit process and suppress side effects resulting from the metal etching process. Density functional theory calculations show that CoCp(CO)₂ has a relatively higher kinetic barrier (36.2 kcal/mol) on SiO₂ than that of Co₂(CO)₈ (22.9 kcal/mol). This indicates that CoCp(CO)₂ could be a promising candidate as a Co precursor for selective CVD. Selective CVD of Co films is demonstrated experimentally by deposition on SiO₂ and Cu substrates at 200 and 300 °C. To reduce C contents in the deposited film, a NH₃ plasma process is adopted into conventional CVD in a cyclic CVD process. This process enables deposition of Co films with lower C content while maintaining selective deposition.