We investigated the effects of in situ NH3 preannealing immediately before sealing nitride deposition on the wordline sheet resistance (Rs) of a tungsten polymetal gate electrode (W/WNx/poly- Si). While in situ NH3 preannealing is very effective for the suppression of W-O whisker formation, it was found that excessively long-time NH3 preannealing could cause an unexpectedly abnormal increase in the wordline Rs of short gate length electrodes, typically < 100 nm. Since X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS) analyses reveal that long-time NH3 preannealing results in the nitridation of tungsten sidewall surfaces, the wordline Rs increase in a small-gate-length sample subjected to long-time NH3 preannealing is mainly due to tungsten sidewall nitridation, which is localized at the surface region of the tungsten sidewall. In addition, at a long-time NH 3-preannealed gate electrode, an abnormal inflation of the tungsten sidewall occurred due to a slight increment in lattice spacing by tungsten nitridation.
|Number of pages||4|
|Journal||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|Issue number||4 B|
|Publication status||Published - 2004 Apr|
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)