Hardness Studies of RF Sputtered Deposited BCN Thin Films

Abstract

In today’s technological advancement of ULSI integration, the inter-dielectric layer (IDL) with small RC delays needs low-k materials which are sturdy enough to withstand mechanical stress posed by multilayer devices. Using organic polymers that are porous in nature can achieve dielectric values as low as 2, but these cannot withstand considerable mechanical stress. Boron Nitride (BN) films can achieve low-k values around and hardness comparable to diamond [1][2]. BN is hygroscopic in nature. In this respect carbon can be added to the BN structure to produce Boron Carbon Nitride (BCN) films as the possible substitute for BN. The minimum dielectric constant achieved by plasma assisted chemical vapor deposition for a BCN thin film was reported to be 1.9. [2] The BCN films are also instrumental in suppressing the Cu migration [3]. The Young’s modulus of BCN films are reported well above 20 GPa making it one of the suitable options for low-k materials [4]. In the present work, BCN films were deposited by RF sputtering of boron carbide (BC) target in nitrogen ambient with argon. The films were deposited under various N2/Ar gas flow ratios. FTIR measurements were performed to find the chemical bonds of the deposited films. Investigations were performed to evaluate the Hardness (H) and Young’s modulus (E) of the deposited films under various conditions.