Chemical bonding structure in porous SiOC films (k < 2.4) with high plasma-induced damage resistance

Abstract

The chemical bonding structure of porous low-k carbon-doped silicon oxide (SiOC) films (k < 2.4) was engineered using plasma-enhanced chemical vapor deposition and electron-beam curing. The high carbon concentration in the SiOC films with di-methyl bonds (Si(CH3)2) is crucial for resistance to plasma-induced damage (PID) and prevention of moisture uptake after the plasma treatment. The mix of di-methyl bonds is believed to be the key to protecting the films from PID because the films retain their hydrophobic characteristics even after plasma treatment. Thus, control of the ratio of di-methyl bonds to mono-methyl bonds (≡SiCH3) in the as-deposited SiOC film is necessary. Selection of trimethyl silane as a precursor for film matrix formation resulted in excellent control of this ratio to obtain highly reliable low-k/Cu interconnects for high-performance logic devices.