Analysis of low-k organosilicon and low-density silica films deposited in HMDSO plasmas

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 400degreesC. The leakage current densities measured for an electric field of 1 MV/cm are less than 10(-9) A/cm(2) 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 O-2 plasma. The dielectric constant of this low-density silica film is 3.5 and its breakdown field is close to 6 MV/cm.