Low dielectric constant films prepared by plasma-enhanced chemical vapor deposition from tetramethylsilane

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Abstract
Dielectric films have been prepared by radio-frequency plasma-enhanced chemical vapor deposition from mixtures of tetramethylsilane with oxygen. The films have been characterized as-deposited and after annealing at 400 °C to determine the thermal stability of their properties. Rutherford backscattering and forward recoil elastic scattering have been used for determination of the composition of the films. Optical properties were characterized by Fourier transform infrared spectroscopy and measurements of the index of refraction and optical gap. The electrical properties were measured in a Si/insulator/metal configuration. It has been found that the index of refraction decreases and the optical gap and dielectric constant increase with increasing oxygen concentration in the gas feed. While the materials did not show a mass or composition loss after annealing, the annealing resulted in a reduction of the dielectric constant of the films. Dielectric constants as low as 3.1 have been obtained after annealing the film deposited from pure tetramethylsilane.