Fluorine-free tungsten films as low resistance liners for tungsten fill applications

Tungsten (W) chemical vapor deposition (CVD) fill has many applications in the semiconductor industry. As the industry continues to scale feature sizes, many challenges arise as features fall below 20 nm. For several device generations, the standard process scheme has included a TiN adhesion layer to dielectrics and a nucleation W layer for CVD W, but these layers consume most of the volume in narrow features. This paper highlights two new low resistivity W liner films which replace both TiN and the nucleation layer and that allow for continued low resistance scaling of W fill: a plasma-enhanced CVD W (PECVD W) film that adheres to dielectrics and a thermal ALD W film which deposits on metals.