Low dielectric constant a-SiOC:H films as copper diffusion barrier

A low-k dielectric barrier based on silicon oxycarbide for copper damascene processes has been developed in this work. The optimal process conditions that allow the deposition of silicon oxycarbide films with a dielectric constant of 3.74 and copper diffusion depth of 290 Angstrom after thermal stress at 400 degreesC for 3 h has been identified. Copper diffusion depth is defined as the copper and dielectric interfacial region with three-order magnitude reduction in copper concentration. A multilayered structure consisting of black diamond/SiOC/Cu/TaN/Si is fabricated. 3-methyl silane and oxygen in varying concentration is used for the deposition of SiOC using plasma enhanced chemical vapor deposition. The composition of the films is studied by Fourier transform infrared spectroscopy. Dielectric constant and dielectric breakdown of the films are also evaluated. Secondary ion mass spectrometry is employed to investigate the copper diffusion property of the films. The electronic component of the dielectric constant has been found to be most significant in affecting the overall dielectric constant in SiOC films. (C) 2003 American Institute of Physics.