Limitation of post-metallization annealing due to hydrogen blocking effect of multilevel interconnect

We investigated a hydrogen blocking effect: prevention of hydrogen diffusion during post-metallization anneal by a metal interconnect situated above the MOSFET, resulting in the degradation of device characteristics. We clarified the impact of this effect on the devices having multilevel interconnects, based on a model that considers hydrogen´s behaviour in a device. To eliminate this effect, we propose optimization of multilevel interconnect layout to minimize the diffusion path of hydrogen. The benefit of implanting hydrogen ions in the back-end process is also demonstrated as a process solution.