Low Temperature Deposition of WNxCy Diffusion Barriers Using WN(NEt2)(3) as a Single-Source Precursor

摘要

Deposition of high quality WNxCy barrier films at very low temperature using aerosol-assisted chemical vapor deposition (AACVD) is reported. The single-source tungsten nitrido complex, WN(NEt2)(3), was designed to reduce the temperature required for WNxCy film deposition in an effort to minimize thermal stresses on neighboring layers in device structures. Using either pyridine or heptane as a solvent, WNxCy films were successfully deposited at temperatures from 100 to 650 degrees C. Film growth in pyridine and heptane at low temperature (100-350 degrees C and 125-550 degrees C, respectively) showed weak temperature dependence consistent with mass-transfer limited growth. At higher temperature the growth rate decreased rapidly with apparent activation energy of 0.375 +/- 0.057 eV. The effects of solvent choice on film properties including composition, crystallinity, density, and surface roughness are discussed. Films deposited at low temperature (<350 degrees C) were highly smooth, amorphous and with a stoichiometry approaching W2NC; characteristics desirable for diffusion barrier applications. In Cu diffusion barrier tests, Cu (similar to 100 nm)/WNxCy (similar to 5.5 nm)/Si stacks subjected to a 500 degrees C anneal for 30 min showed no indication of Cu diffusion or intermixing of layers, as verified by XRD, 4-point probe, SEM etch-pit test, and TEM. (C) The Author(s) 2014. Published by ECS. All rights reserved.