Physical and barrier properties of PECVD amorphous silicon-oxycarbide from trimethylsilane and CO2

Abstract

This work investigates the thermal stability and physical and barrier properties of amorphous silicon-carbide (alpha-SiC) and amorphous silicon-oxycarbide (alpha-SiCO) dielectric barriers deposited by plasma-enhanced chemical vapor deposition (PECVD) using trimethylsilane (3MS) precursor and He carrier gas. Films were deposited without and with various CO2 flow rates. The dielectric constant of the alpha-SiCO films decreased with increasing CO2 flow rate. Increasing CO2 flow rate also promotes better thermal stability, higher breakdown field, lower leakage current, and superior resistance to Cu diffusion through the films. The improved barrier property is attributed to the denser and less porous structure of the alpha-SiCO dielectric barrier upon CO2 addition. The alpha-SiCO barrier films deposited with the large (1200 Seem) CO2 flow rate exhibit the low k value of 3.7, thermal stability up to 550degreesC, room-temperature breakdown field of 8 MV/cm and leakage current densities of 10(-7) to 10(-6) A/cm(2) at 3 MV/cm, and a superb Cu barrier property. (C) 2004 The Electrochemical Society.