Effects of ultraviolet irradiation treatment on low-k SiOC(−H) ultra-thin films deposited by using TMS/O2 PEALD

We report on the electrical characteristics for the metal-insulator-semiconductor (MIS) structure of low-dielectric-constant SiOC(−H) films. The SiOC(−H) thin films were deposited on p -Si(100) substrates by using a plasma-enhanced atomic layer deposition (PEALD) system. To improve the structural and the electrical characteristics, we post-treated the SiOC(−H) films deposited using PEALD with ultraviolet (UV) irradiation for various time intervals. The radical intensities in the bulk plasma were observed to be influenced strongly by the radio-frequency (rf) power. A complete dissociation of the trimethylsilane (TMS) precursor took place for rf powers greater than 300 W. As the UV treatment time was increased, the bonding structure of the SiOC(−H) film clearly separated to Si-O-Si and Si-O-C bonds. Also, the fixed charge density and the interface state density on the SiOC(−H)/ p -Si(100) interface decreased as the UV treatment time was increased to 6 min. Therefore, we were able to minimize the defects and to reduce the interface charge by adjusting the UV dose.