Process for chemical vapor deposition of tungsten onto a titanium nitride substrate surface

摘要

A process for chemical vapor deposition of blanket tungsten thin films on titanium nitride proceeds by hydrogen reduction of tungsten hexafluoride at temperatures of 200 to 500° C. Tungsten film nucleation is preferably facilitated by partial removal of the oxidized surface of titanium nitride or titanium nitride coated substrates by a sputter cleaning process prior to the tungsten CVD. The process differs in part from other processes in that deposition proceeds rapidly on titanium nitride without a significant nucleation period without the addition of other chemical compounds such as silane. The sputter cleaning process preferably takes place in an inert vacuum environment that protects the substrate from atmosphere and oxygen until the tungsten CVD step occurs. The process is particularly advantageous where the substrate has a titanium nitride surface that had been created in a separate location such as by a reactive sputter coating process from which the substrate must be transferred through ambient atmosphere containing oxygen. The advantages of the invention can be partially attained or enhanced by isolating the substrates from an oxygen containing environment between the creation of the titanium nitride surface and the initiating of the tungsten CVD.