Defects and electronic transport in hydrogenated amorphous SiC films of interest for low dielectric constant back end of the line dielectric systems

Abstract

Back end of line dielectrics with low dielectric constants are needed for current and future integrated circuit technology. However, an understanding of the defects that cause leakage currents and limit reliability in these films is not yet developed. We utilize conventional electron paramagnetic resonance (EPR), electrically detected magnetic resonance (EDMR), and leakage current measurements, complimented by Fourier transform infrared spectroscopy and Rutherford back scattering results, to investigate a-SiC:H dielectrics which have great potential use for back end of line dielectrics. We observe a strong correlation between conventional EPR defect density measurements and leakage currents. There is also a very strong correlation between hydrogen content and both leakage current and EPR defect density. The close correspondence between the EPR results and the leakage currents strongly indicates that the defects observed by EPR are largely responsible for the leakage currents and likely limit the dielectric reliability. Important reliability phenomena in these films are time-dependent dielectric breakdown and stress induced leakage current. Additionally, we have utilized EDMR via spin dependent trap assisted tunneling to investigate the direct link between defects observed in EPR and electrical transport.