DIFFUSION BARRIER EFFECTS AGAINST CU OF W-N LAYER FORMED BY ELECTRON-CYCLOTRON-RESONANCE PLASMA NITRIDATION ON W-LAYER

To improve the diffusion barrier effects of W against Cu, W-N/W multilayers formed by electron cyclotron resonance (ECR) N-2 plasma exposure on W layers were investigated. Cu/W-N/W/Si multilayer structures were measured using secondary ion mass spectroscopy (SIMS), Rutherford backscattering spectroscopy (RES), Auger electron spectroscopy (AES), and electric resistance change. The W-N/W films showed a dramatic improvement in barrier properties over those of metallic W films. When the thickness of the W-N/W barrier layer was only 5 nm, the Cu/W-N/W/Si multilayer retained the multilayer structure even after annealing at 873 K for 1 h in H-2 without increase of resistivity. The thickness of the W-N layer formed by ECR plasma nitridation was less than 1-2 nm, which provided an excellent barrier effect.