Experimental study of multilayer SiCN barrier film in 45/40 nm technological node and beyond

摘要

With feature size of device scaled down 45 nm technological node and beyond, the backend of the line (BEOL) faces too many problems such as resistance-capacitance (RC) delay, crosstalk noise, and power consumption. In order to improve RC delay, the SiCN dielectric constant had to further decrease through introducing C2H4 gas to increase its carbon content. The SiCNkI (k similar to 5.3) and SiCNk(II) (k similar to 3.8) were characterized by spectroscopic ellipsometer, fourier transform infrared spectroscopy (FTIR), Rutherford backscattering spectrometry-hydrogen forward scattering (RBS-HFS), X-ray reflectivity (XRR), Hg probe, four point bending (4-PB) test, scanning electron microscope (SEM), and transmission electron microscope (TEM). Results indicated that the hardness and modulus and density of the SiCNk(II) were lower than that of the SiCNkI. RBS-HFS and FTIR examination indicated that SiCNk(II) barrier film had high carbon content and terminating CH3 group to cause low cross-linking and density of dielectric films resulting in large volume. 4-PB test combined with transmission electron microscope (TEM) examination demonstrated that the crack occurred in the interface between SiCNk(II) film/SiCNkI bilayer barrier film and low k film. After adding SiCNkI barrier film, no crack was found using SiCNk(I)/SiCNkII film/SiCNkI tri-layer barrier film. In addition, the capacitance and RC reduction ratios were improved to about 7-8% using the SiCNk(II)/SiCNk(I) bilayer barrier film. (C) 2015 Elsevier Ltd. All rights reserved.