Tungsten corrosion and recess improvement by feasible slurry and clean chemical in WCMP process

Serious tungsten corrosion after tungsten chemical mechanical planarization (W CMP) is found to correlate to the high via resistance. According to via design layout analysis, the W plug recess is strongly dependent on the underlying metal line area and via hole size. The via W plug recess becomes worse as via size shrinkage and underlying metal line area increasing. The low corrosion W polishing slurry, alkali /acidic buffing slurry and clean chemical are studied. The result indicates that low corrosion W slurry and acidic clean chemical can suppress tungsten corrosion and result in tightened via resistance distribution in 1× nm device product.