A study on low dielectric material deposition using a helicon plasma source

Abstract

Characteristics of SiOF films deposited by a helicon plasma source have been investigated using Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, and ellipsometry. High density Ar plasma of >10(12) cm(-3) was obtained on a substrate at low pressure (<10 mTorr) with RF power of >400 W using a helicon plasma source. The effect of the RF power, the magnetic field strength, and the pressure on the helicon wave for high density plasma has been studied. A gas mixture of SiF4, O-2, and Ar was used to deposit SiOF film on 5 in. (100) Si wafers not intentionally heated. Optical emission spectroscopy was used to study the relation between the relative densities of the radicals and the deposition mechanism. The effects of the RF power, the gas composition, and the Ar addition to the SiF4/O-2 mixture on the plasma-phase composition and on the properties of the film, have been studied. Discharge conditions such as gas composition, sheath potential, and relative densities of the radicals affect the properties of the film. The dielectric constant of the SiOF film deposited using the helicon plasma source was 3.1, a value lower than that of the oxide films obtained using other methods.