Formation of composite tungsten films

A method for forming a composite tungsten film, comprising:

• positioning a substrate within a process chamber;
• forming a tungsten nucleation layer on the substrate by subsequently exposing the substrate to a tungsten precursor and a reducing gas during a cyclic deposition process, wherein the tungsten nucleation layer has a thickness of less than about 100 Å;
• and
• forming a tungsten bulk layer during a chemical vapor deposition process, comprising:
• exposing the substrate to a deposition gas comprising the tungsten precursor;
• and
• depositing the tungsten bulk layer over the tungsten nucleation layer.

A method for forming a composite tungsten film, comprising:

• positioning a substrate within a process chamber;
• forming a tungsten nucleation layer on the substrate by subsequently exposing the substrate to tungsten hexafluoride and a reducing gas during a cyclic deposition process, wherein the reducing gas comprises diborane and hydrogen gas;
• and
• forming a tungsten bulk layer during a chemical vapor deposition process, comprising:
• exposing the substrate to a deposition gas comprising the tungsten hexafluoride;
• and
• depositing the tungsten bulk layer over the tungsten nucleation layer.