Effects of He (90%)/H2 (10%) plasma treatment on electric properties of low dielectric constant SiCOH films

Abstract

In microelectronics industry, integration of the low dielectric constant (low-k) material films is a continuing issue due to the decreasing device feature size. To improve electric properties, various post-deposition treatments of the low-k material films can be used. In this work, we used room temperature treatment of He/H2 plasma and investigated the effects of plasma treatment on the electrical properties of low-k SiOCH films. Plasma treatment time changed from 300 to 1800s. After treatment, the dielectric constant was decreased from 2.9 to 2.48, and the thickness of the low-k SiCOH films changed by only ∼5%. The leakage current densities of the low-k SiCOH films were decreased to ∼10−11A/cm2, with treatment time ≥600s. The breakdown occurred only around 2V for films plasma-treated for 600 and 900s. However, for 1800s treatment time, the breakdown voltage was enhanced dramatically and breakdown occurred at applied voltage higher than 40V. The surface composition change of the films after treatment was investigated by X-ray photoelectron spectroscopy (XPS). As the plasma treatment time was increased, the intensities of CC/CH and CSi peaks were decreased while the intensities of SiO and CO peaks were increased. It is thought that increase of oxygen content of the SiCOH film, after plasma treatment, contributed to leakage current reduction and breakdown voltage increase.