The Mechanism of Instability on Device’s Characteristicsdue to Inter-metal Dielectrics with Low-k Material and the Modified Process

摘要

[[abstract]]In this paper, the effects of back-end process on device characteristic shift are explored. It had been found that the transistors with different inter-metal-dielectric (IMD) films have different performance. Moreover, more of the IMD layers will result in more of the electrical characteristic shifts. The shift is dominated by the interface state reduction. The mode of plasma-enhanced hydrogen out- diffusion during IMD film deposition is proposed to explain the BEOL-relate device shift. In order to relive this effect of electrical characteristic shift, another alloy step by pure hydrogen anneal is implemented after metal-1 etch and before the Via-1 deposition. It is found the electrical characteristics taken at metal-1 stage are very close to those taken at melal-6 with passivation step. In addition, there is no apparent hot carrier lifetime degradation with or without the pure hydrogen treatment.