Refractory metal plug forming method

Abstract

Abstract A method for forming a plug in a connecting hole formed in an interlayer insulating film by filling a layer of a refractory metal in the connecting hole, in which the surface of a tungsten layer produced by a selective CVD method or a blanket CVD method (Blk-CVD method) with rough surface morphology is smoothed to produce the plug with high reliability. With the present method, the tungsten layer is formed, such as by the selective CVD method, as far as an intermediate depth of the connecting hole, the surface of the tungsten layer is smoothed, and an upper metallization layer is formed by a layer of another metal material. In this manner, bonding between the tungsten layer and the upper metallization is improved and contact resistance is diminished. Deposits of tungsten oxyfluoride or sulfur are utilized for smoothing. The deposition process of these deposits occur preferentially in minute recesses on the surface of the tungsten layer, while an etching reaction proceeds preferentially on minute lands on the surface, for achieving the smoothing. By such smoothing, generation of residues or transcription of the rough surface morphology of the tungsten layer to the underlying layer may be prevented to improve process reliability.

Inventors

• 👤 Masakazu Muroyama
• 👤 Junichi Sato

Bibliographic Details