Characteristics of W and Cu/W gate MOS diodes fabricated by a process utilizing LPCVD of W and Cu lift-off

MOS diodes having double layer Cu/W, W, or Al gates were fabricated using tungsten chemical vapor deposition, copper evaporation and lift-off and were characterized before and after thermal anneals. The breakdown field statistics were determined for all kinds of devices, while the high field conduction and charge trapping in the oxide were investigated. The W gate devices exhibited high performance and very low degradation even after annealing at 650 °C. In Cu/W gate diodes good barrier action of our LPCVD tungsten films against copper penetration after annealing at 510 °C was observed, while reduced breakdown integrity and degradation due to copper diffusion occurred after annealing at 650 °C.