Investigation of the Dielectric and Mechanical Properties for Magnetron Sputtered BCN Thin Films

Abstract

Boron carbon nitride (BCN) thin films were deposited by a dual target DC and RF sputtering technique. The films were deposited using various combinations of nitrogen and argon working gases and B 4 C, BN, and C targets. X-ray photoelectron spectroscopy and Fourier-transform infra-red spectroscopy were utilized, respectively, to investigate the changes in chemical composition and bonding that occurred for films deposited under various N 2 /Ar gas flow ratios and DC/RF target powers. The composition and bonding were correlated to separate measurements of the BCN mass density, dielectric constant, Young's modulus, and hardness. All BCN films were observed to have relatively low mass densities ranging from 2.0-2.5 g/cm 3 . BN rich BCN films were observed to be insulating with relatively low dielectric constants of 3.9-4.6 and Young's modulus and hardness values of 110-150 GPa and 5-13 GPa, respectively. BC rich BCN films were observed to be comparatively leaky dielectrics but did exhibit extreme mechanical properties with Young's modulus and hardness values exceeding in some cases 300 GPa and 30 GPa, respectively. Nanoelectronic metal interconnects have many unique nanoscale electrical, thermal, and mechanical challenges.1-3 While dimensional scaling has produced tremendous improvements in transistor performance, 4 it has produced an opposite effect on the associated metal interconnect leading to increased critical path signal delays and possible degradation of the overall integrated circuit performance.5 As the interconnect signal delays are proportional both to the resistance of the interconnect metal and the capacitance of the insulating interlayer dielectric (ILD), new materials with reduced values of resistivity and dielectric permittivity have been sought to mitigate the negative effects of dimensional scaling.5 Since relatively few materials exhibit a lower resistivity compared to the currently utilized interconnect metal copper (Cu), most materials based interconnect delay reduction efforts have focused on implementing new ILD materials with increasingly lower values of dielectric constant (i.e. low-k).6 Unfortunately, the hybrid inorganic-organic silicate (a-SiOC:H) materials currently utilized as low-k ILDs exhibit reduced electrical, thermal and mechanical properties in addition to reduced values of dielectric permittivity.5-7 These overall reduced properties have severely aggravated a variety of interconnect related reliability issues such as time dependent dielectric breakdown and die cracking during packaging. 2,3Compounds in the boron-carbon-nitrogen phase diagram (such as diamond (C), cubic boron nitride (c-BN), and boron carbide (B 4 C)) are potentially attractive as alternative low-k dielectric materials due to their covalent bonding, short bond lengths, and low atomic mass that leads to a unique combination of low dielectric constant but high thermal and mechanical strength. [8][9][10][11][12] Some of the already prominently reported properties for these materials include good wear resistance, hig...

Self-Ordered Orientation of Crystalline Hexagonal Boron Nitride Nanodomains Embedded in Boron Carbonitride Films for Band Gap Engineering

“…The atomic bonding similarity amongst boron (B), carbon (C), and nitrogen (N) allows for the formation of a ternary boron carbonitride (BCN) system with a wide compositional range, including typical materials, such as diamond, graphite, fullerene, cubic BN (c-BN), hexagonal BN (h-BN), B 4 C, C 3 N 4 , BCN, BC 2 N, and so on [1][2][3], consequently, when combining their properties, making them adaptable for diverse applications [4][5][6]. Particularly, hybridizing between semi-metallic graphite and insulating BN [7], BCN ternary exhibits excellent semiconducting properties with an adjustable band gap, hence making it a suitable candidate in optoelectronic devices, luminescent devices, transistors, and micro-electrical-mechanical system (MEMS), just to name a few [8][9][10][11][12].…”

Feasibility of Etching Studies on BCN Thin Films

“…The R. F power for the BN target was maintained at 250 W while the DC power of 20 W was used for B 4 C target during sputtering. The thicknesses of the deposited films were measured by Veeco Dektak-150 profilometer.…”

“…4 Umeda et al were able to deposit non-porous BCN films with dielectric constant as low as 1.9. 5 A low dielectric constant (i.e.…”

A brief overview of RF sputtering deposition of boron carbon nitride (BCN) thin films

“…BCN films were also synthesized by DC and RF magnetron sputtering using a combination of B 4 C, BN, and C targets in Ar/N 2 ambient to study the mechanical and dielectric properties such as mass density, hardness, Young's modulus, and dielectric constant [110]. They examined the chemical composition and chemical bonding of the deposited films using XPS and FTIR.…”