Optical emission spectroscopy investigation on SiCOH films deposition using decamethylcyclopentasiloxane electron cyclotron resonance plasma

Abstract

This paper investigates the characterization of decamethylcyclopentasiloxane electron cyclotron resonance plasma at different ECR position and field distribution, which were used as a precursor to deposit SiCOH low dielectric constant films. An ECR position threshold for microwave energy couple is found. Before this ECR position threshold, the radicals show an unsaturated distribution. However, a saturation radical distribution can be obtained after the position threshold. According to the radical distribution, the possible chemical reactions in ECR discharge plasma are presented and the relationship between SiCOH films structure and the radical distribution is analyzed. The results show that at a high ionization degree of DMCPS, the fivefold Si–O rings break and form new threefold Si–O rings. Meanwhile, more Si–OH groups break and form Si–O–Si linkages by a condensation chemistry occurring between proximal Si–OH groups. This helps to reduce the k value of SiCOH films.