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. •CoCp(CO)2 with moderate kinetic barrier on SiO2 is a potential precursor for selective CVD.•Selective CVD of Co is achievable below a process temperature of 300 °C.•Approximately 82% of C content in the Co film was reduced by NH3 plasma treatment for 4 min.•The cyclic CVD with NH3 plasma enables reduction of C in the Co film while maintaining the DS.