Tungsten missing was observed at the interface between contact barrier layer and W in the 28 nm node contact process. The potentiodynamic polarization scans showed that H 2O 2 in the W chemical-mechanical- polishing slurry increased the potential difference between the diborane (B 2H 6) reduced atomic layer deposited (ALD) W and TiN, suggesting that there is a high tendency for galvanic corrosion to occur. This potential difference kept constant, but the corrosion current density increased when the H 2O 2 concentration increased. The TEM image showed the depth of ALD W missing is proportional to the H 2O 2 concentration, which agrees with the electrochemical testing results. ALD W films with various pre- and post-treatments and their correlations with the degree of W missing were also investigated.
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