Mechanical properties of Si-C-O-H low-k dielectrics prepared by plasma enhanced chemical vapor deposition

Mechanical properties of low dielectric constant (low-k) materials are one of the key areas that need to be better understood in order to improve copper/low-k dual damascene integration. In this paper, mechanical properties of carbon doped oxide (CDO) films deposited using TMCTS and CO₂ as precursors are reported. Differences in Young´s modulus, residual stress and fracture toughness for films prepared by two processes A and B have been observed and are correlated to carbon contents using Fourier transform infrared spectroscopy (FTIR). For similar carbon content, process B films show higher modulus and toughness and lower stress than process A films. Fracture toughness calculated from critical thickness measurement indicates bimodal behaviors for process B films. Analysis of detailed chemical bonding structures is needed to further understand the mechanical properties of low k dielectrics. While this work was performed using a particular CDO formulation, the methodology and considerations are applicable to a range of nano materials. Therefore, these methods and results will prove to be useful to a wide range of industries interested in integrating nano-materials into complex structures.