Tungsten plug corrosion on B2H6-based nucleation layer induced by WCMP process

Abstract

The topic of this paper is to identify tungsten plug corrosion issue at the interface of barrier metal and W bulk in W-CMP process. Two types of nucleation layers in W-CVD deposition process - SiH₄ and B₂H₆ based were studied. The B₂H₆ based nucleation W will induce W corrosion. However, SiH₄ based nucleation W does not have the issue. The static etch rate, electrochemical properties and removal rate (R.R.) of two types W-CMP slurries and SiH₄ and B₂H₆ based nucleation W were evaluated. It has been demonstrated that the B₂H₆ based nucleation film has much higher intensity of static etching on various W slurries. The B₂H₆ based nucleation layer is weak than SiH₄ based, and it induces corrosion during W-CMP process.