Diffusion Barrier Mechanism of Extremely Thin Tungsten Silicon Nitride Film Formed by ECR Plasma Nitridation

概要

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The diffusion barrier mechanism of tungsten silicon nitride (WSiN) film formed by ECR plasma nitridation is investigated. For this purpose, we examined film thickness, nitrogen content, surface composition, and local atomic ordering of this WSiN and correlated these characteristics with its barrier capability. It is revealed that WSiN shows good barrier capability when RF bias is applied to the substrate during nitridation even though it is less than 6-nm thick. Applying RF bias increases the nitrogen content in WSiN. Moreover, Si atoms are preferentially sputtered and the local atomic ordering in WSiN is lowered because the effect of ion bombardment is remarkably pronounced. It is supposed that these film characteristics contribute to the suppression of phosphorus diffusion through interstitial sites. As a result, WSiN functions as an excellent barrier layer even though it is extremely thin.
社団法人応用物理学会の論文
1998-03-30