High-density plasma chemical vapor deposition of amorphous carbon films

This work investigated the influence of the plasma parameters pressure and RF power on the characteristics of amorphous carbon films deposited by high-density plasma chemical vapor deposition, using inductively coupled methane plasmas. These films show several good electrical characteristics: high resistivity, low dielectric constant and high breakdown field. After deposition, the films were characterized as follows: the thickness was measured with a step height meter and an ellipsometer; Fourier transform infrared spectroscopy was used to identify the sp² and sp³ hybridization of C and CH bonds and other possible bonds that can appear because of the hydrogen presence; atomic force microscopy was used to measure the film roughness and I–V and C–V measurements to determine the dielectric constant, the electric resistivity and the breakdown electric field. The films deposited with high-density plasmas showed good characteristics for several applications, when compared to deposition with conventional RF plasmas. These films show a better structural quality with a high sp³ to sp² ratio. Even with this high sp³ to sp² ratio, the RMS surface roughness of an approximately 300 nm thick film was only 0.24 nm. For microelectronic applications, a very low dielectric constant of only 1.68 and a high resistivity of 1.5×10¹⁴ Ω cm were obtained.