Preclean of aluminum trench and via patterned substrates is vital for successful selective chemical vapor deposition of tungsten (CVD-W). A convenient preclean method uses in situ. BCl3 plasma etching to remove the native metal oxide prior to conducting the CVD-W. During the plasma etching, however, the outsputtered aluminum oxide and aluminum can be redeposited on the sidewall of the trench and via hole and on the surface of the dielectric layer, where W nucleation is induced, resulting in creep-up and selectivity loss during tungsten deposition. By using a solution of hydroxylamine sulfate to pretreat the aluminum trench and via hole patterned substrates, we successfully avoid the creep-up and selectivity loss of W deposition.