Nitridation of fine grain chemical vapor deposited tungsten film as diffusion barrier for aluminum metallization

Kow-Ming Chang*, Ta Hsun Yeh, I. Chung Deng

*Corresponding author for this work

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

A novel tungsten nitride (WNx) film for diffusion barrier applications has been prepared by nitridation of a fine grain chemical vapor deposited tungsten (CVD-W) film. The fine grain CVD-W is deposited at 300°C in a low pressure chemical vapor deposition reactor with a SiH4/WF6 flow rate of 12.5/5 sccm under a total gas pressure of 100 mTorr. The subsequent nitridation process is executed in nitrogen plasma at 300°C without breaking vacuum. The thickness of WNx layer as examined by secondary ion mass spectroscopy is 50 nm after 5 min exposure to nitrogen plasma. X-ray photoelectron spectroscopy spectra shows that the atomic ratio of tungsten to nitrogen in WNx layer is 2:1. According to the analysis by Auger electron spectroscopy and the measurement of n+p junction leakage current, the Al/WNx/W/Si multilayer maintains excellent interfacial stability after furnace annealing at 575°C for 30 min. The effectiveness of W2N barrier is attributed to stuffing grain boundaries with nitrogen atoms which eliminates the rapid diffusion paths in fine grain CVD-W films.

Original languageEnglish
Pages (from-to)3670-3676
Number of pages7
JournalJournal of Applied Physics
Volume81
Issue number8
DOIs
StatePublished - 15 Apr 1997

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