Optical and XPS studies of BCN thin films by co-sputtering of B4C and BN targets

Boron carbon nitride (BCN) thin films are investigated for their optical properties. BCN, is the unanimous choice for inter-dielectric layer (IDL) in very large scale integration (VLSI) because of its low-k dielectric constant. Optical properties can be tailored as a function of elemental composition, which makes BCN a prospective material in UV-filters and mirrors. Films are deposited by reactive co-sputtering of boroncarbide (B4C) and boronnitride (BN) with varying N2/Ar gas flow ratio by DC and RF sputtering respectively. XPS studies are performed to deduce the bonding and chemical properties of the BCN thinfilms. Optical band gap (Eg) studies are performed as a result of varying target powers, gas ratios and deposition temperatures. Eg is found to increase with N2/Ar flow ratios and deposition temperatures. BCN deposited at 20 W DC exhibited higher band gap range and the highest achieved is 3.7 eV at N2/Ar = 0.75. Lowest value achieved is 1.9 eV at N2/Ar = 0.25 for as-deposited films.