Thermal atomic layer deposition of molybdenum carbide films using bis(ethylbenzene)molybdenum and H2

Abstract

To fully exploit the excellent characteristics of molybdenum carbide (MoCx) for advanced semiconductor applications, which require high conformality and very low thickness, the atomic layer deposition (ALD) of MoCx must be developed. In this study, the thermal ALD of MoCx was investigated for the first time using halogen-free bis(ethylbenzene)molybdenum (BEBMo) and H2 (4% in 96% Ar) at deposition temperatures ranging between 180 and 280 °C. ALD MoCx films prepared using BEBMo and H2 exhibited an ALD window of 200−240 °C, moderate growth of 0.034 nm/cycle, and high conformality (∼91%) on the trench substrate. Chemical analysis revealed that the ALD MoCx films predominantly consisted of Mo2C (Mo2+ oxidation state) with a Mo/C atomic ratio of 1.25 and 4% oxygen as an impurity. The as-deposited MoCx films were amorphous at all deposition temperatures, but they crystallized to hexagonal β-Mo2C after post-deposition annealing (PDA) at 600 and 700 °C. The resistivity of the as-deposited MoCx films grown at 250 °C was only 171  μΩ cm at 23 nm, but the resistivity significantly increased to 711  μΩ cm as the film thickness decreased to 4.4 nm. After PDA at 700 °C, the MoCx films showed remarkably low resistivities of 73−104  μΩ cm in the thickness range of 5−23 nm.