A comparative study of low dielectric constant barrier layer, etch stop and hardmask films of hydrogenated amorphous Si-(C, O, N)

Abstract

New barrier layer, etch stop and hardmask films, including hydrogenated amorphous a-SiC x :H (SiC), a-SiC x O y :H (SiCO), and a-SiC x N y :H (SiCN) films with a dielectric constant ( k) approximately 4.3, are produced using the plasma-enhanced chemical vapor deposition technique. The chemical and structural nature, and mechanical properties of these films are characterized using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and nano-indentation. The leakage current density and breakdown electric field are investigated by a mercury probe on a metal-insulator-semiconductor structure. The properties of the studied films indicate that they are potential candidates as barrier layer, etch stop and hardmask films for the advanced interconnect technology. The SiC film shows a high leakage current density (1.3×10 −7 A/cm 2 at 1.0 MV/cm) and low breakdown field (1.2 MV/cm at 1.0×10 −6 A/cm 2). Considering the mechanical and electrical properties requirements of the interconnect process, SiCN might be a good choice, but the N content may result in via poison problem. The low leakage current (1.2×10 −9 A/cm 2 at 1.0 MV/cm), high breakdown field (3.1 MV/cm at 1.0×10 −6 A/cm 2), and relative high hardness (5.7 GPa) of the SiCO film indicates a good candidate as a barrier layer, etch stop, or hardmask.