Chemical vapor deposited tungsten interconnect technology

A `composite´ chemical vapor deposited tungsten process was developed for interconnect application. This film demonstrated stress levels <550 MPa tensile, whilst maintaining acceptable fill properties. It was found that the SiH₄ initiation step (no WF ₆ flowing) was critical for the control of Si consumption and junction leakage, and that a higher (40 Torr) process pressure provided substantial benefits as compared to initiation steps performed at lower pressures (4 Torr). The addition of relatively low N₂ partial pressures to the process gas mixture greatly reduced the surface roughness of the CVD-W film, with no detrimental effect on other film properties