Highly conductive tungsten thin films prepared by the plasma-assisted silane reduction process

Abstract

We have studied the properties of plasma-enhanced chemical vapor deposited tungsten (PECVD-W) thin films accord­ing to the variations of reactant mixtures, SiH4/WF6 ratio, deposition temperature and RF power density. As the result, it is found that the resistivity of PECVD-W is reduced from 70 to 40 /ifi-cm with the addition of SiH4 (SiH4/WF6 ratio = 1) even at a lower temperature (220°C) than in the previous works. For the further reduction of resistivity, with in­creasing deposition temperature from 220 to 360°C, 40 /ifi-cm is reduced to 10 /iH-cm, and (110), (200) and (211) oriented ce-phase grain growth is observed. The deposition rate is increased with the increase of the SiH4/WF6 ratio up to 1.5. However, at the SiH4/WF6 ratio of 2, the deposition rate decreases and (3 peaks are observed at the expense of the a- phase. The Auger in-depth profile indicates that 20 atomic % is incorporated into the deposition process. ？ 1991 The Japan Society of Applied Physics.