Stability of TiB2 as a diffusion barrier on silicon

Article abstract of DOI:10.1149/1.2085367

The stability of low-pressure chemical vapor-deposited TiB₂ films has been investigated for their potential use as diffusion barriers between Al or Cu metallurgy and the Si substrate during post-metal annealing at temperatures ranging from 450-640°C for Al, and 500-800°C for Cu. Although no evidence of intermixing was observed via Rutherford backscattering spectroscopy (RBS) for TiB₂/Si samples rapid thermal-annealing (RTA) up to 1080°C, pyramid-shape pits in the Si, bounded by (111) planes, were observed using transmission electron microscopy for the samples annealed above 950°C. Secondary ion mass spectroscopy depth profiles of B in Si originating from the TiB₂ solid source suggested enhanced diffusion after RTA. According to RBS spectra coupled with scanning electron microscopy (SEM) examination, Al/TiB₂/Si (pre-annealed) stacks appeared to be stable up to 500°C for 30 min in forming gas. For the stacks with as-deposited (amorphous) TiB₂ films, plan-view SEM of Al/TiB₂/Si showed very limited reaction with Al up to 600°C, in good agreement with sheet resistance measurements. The as-deposited, amorphous TiB₂ films were superior diffusion barriers compared to the annealed, polycrystalline TiB₂. No interaction took place between sputtered Cu and an underlying, amorphous TiB₂ film up to 750°C, 30 min in vacuum. Plan-view SEM, RBS, and sheet resistance measurements showed that the structure started to break down at 775°C.

Full text of DOI:10.1149/1.2085367

Downloaded on 2014-10-28 to IP 129.82.28.124 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2014-10-28 to IP 129.82.28.124 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2014-10-28 to IP 129.82.28.124 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2014-10-28 to IP 129.82.28.124 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2014-10-28 to IP 129.82.28.124 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2014-10-28 to IP 129.82.28.124 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).