Novel Approach for W Loss Defect Prevention on WCMP Re-Clean Process

With the device dimension rapidly shrinking, Tungsten Chemical Mechanical Polishing (WCMP) becomes one of the critical manufacturing processes for multi-layer interconnection of ULSI (ultra large scale integrated) circuits. The effectiveness of Post-CMP cleaning is one of critical step for particles removal and product Cp yield improvement. WCMP re-clean process is a general way to further reduce particles on high-defect-density impacted wafers in IC manufacturing. However, W loss defect could be generated frequently due to the extra re-clean process introduced in post WCMP step for sub-0.13um devices. In this paper, the mechanism of W loss defect after re-clean process is studied. Also one novel approach is proposed to prevent W loss and improve product CP yield.