The constraints of corning on the W plug in W chemical mechanical planarization (CMP) were investigated by controlling the corrosion behavior and static etch rate of the W film. Poly(acrylic amide) (PAM) was used as an inhibitor to decrease the static etch rate of the W film. The interaction between PAM and the surface of the W film was determined by potentiostatic measurement using a potentiometer and by force measurement using an atomic force microscope (AFM). AFM results revealed that the adlayer of PAM formed on the W film, which prevented the oxidation of the W film. Consequently the addition of PAM suppressed the corning defect on the W plug in a W CMP test that used patterned wafers.