Effects of barrier-metal schemes of tungsten plugs and blanket film deposition

This work investigates the effects of various contact integration schemes on tungsten (W) plug formation. The deposition rate, surface morphology, sheet resistance and reflectivity of W deposited on various substrates are also characterized. Experimental results indicate that the titanium nitride (TiN) film which does not undergo post-rapid-thermal-processing (RTP) treatment has a higher W deposition rate than TiN film which under goes the post-RTP treatment. The W plug formed on chemical vapor deposition (CVD) TiN has easily found voids, which result in high contact resistance. To reveal the relationship of CVD TiN process conditions and W plug loss, process variables including film thickness, plasma ambient, in situ plasma treatment periods and cycles are tested. According to these results, plasma ambient has a strong influence on W plug loss during the etch-back process. In addition, the electrical characteristics of various contact integration schemes are examined in terms of both n(+) and p(+) contact resistance. This work also proposes a superior contact integration scheme to achieve low contact resistance and high production efficiency.