The barrier characteristics of tungsten nitride/tungsten (WNx/W) bilayer formed by an in situ nitridation on a thin chemical vapor deposited amorphous-like tungsten (CVD a-W) film in CVD-W/Si contact system have been investigated. The thickness of WNx layer after a 5 min of N2 plasma exposure at 300°C approximated 50 nm and the atomic ratio of W to N in WNx layer was 2 1. In the CVD-W/a-WNx/a-W/Si multilayered sample, no discernible tungsten suicide was detected by X-ray diffractometer (XRD) at W/Si interface after annealing at 750°C. Meanwhile, with the Rutherford backscattering spectroscopy (RBS) analysis and the measurement of p+n junction leakage current, the CVD-W/a-WNx/a-W/Si multilayer maintained the integrity of interface and the CVD-W/a-WNx/a-W/p+n diode kept the reverse leakage current density less than 9 × 10-9 A/cm2 while the post annealing was carried out at 700°C for 30 min. As the experimental results, the effectiveness of amorphous-like WNx/W bilayered diffusion barrier is attributed to stuff grain boundary with N atoms as well as to eliminate the rapid diffusion paths by using CVD a-W material.
|Number of pages||9|
|Journal||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|Issue number||3 A|
|State||Published - 1 Dec 1999|
- Diffusion barrier
- Gas phase nucleation