Analysis of Low-k Organosilicon and Low-Density Silica Films Deposited in HMDSO Plasmas

Abstract

Low-dielectric constant (low-k) films have been prepared by plasma-enhanced chemical vapor deposition from hexamethyldisiloxane (HMDSO). The films are analyzed by ellipsometry, infrared absorption spectroscopy while their electrical properties are deduced from C–V and I–V measurements performed on metal/insulator/silicon structures. First, it is shown that the carbon-containing silicon oxide films deposited in HMDSO and HMDSO/Ar plasmas have a dielectric constant equal to 3.0 ± 0.1 and are thermally stable at 400°C. The leakage current densities measured for an electric field of 1 MV/cm are less than 10−9 A/cm2 and the breakdown fields are in the range of 6–7 MV/cm. Then, a low-density silica film was obtained by exposing a film deposited in an HMDSO plasma to an O2 plasma. The dielectric constant of this low-density silica film is 3.5 and its breakdown field is close to 6 MV/cm.