It is commonly observed that tungsten (W) thin fi lms deposited by sputtering at room temperature have a metastable β-phasewith relatively high resistivity and transform into a stable α-phase with relatively low resistivity under certain conditions. In this study, to obtain W fi lms with low resistivity suitable for interconnect materials for semiconductors, we tried toidentify deposition parameters for the formation of α-phase W by varying the substrate bias and argon (Ar) pressure in aradio-frequency (RF) magnetron sputtering system. In the initial stage for 1 s of deposition under 20 mTorr and a substratebias of − 100 V, β-phase W nanoparticles were observed using transmission electron microscopy (TEM). However, as thedeposition time increased to 10 min under the same pressure and bias condition, the W fi lm became a mixture of α- andβ-phases. The fraction of α-phase W increased further as the negative bias increased from − 100 to − 200 V. In addition, thefi lm density increased and the surface roughness decreased as the bias changed from + 100 to − 100 V. These results indicatethat the negative bias triggered the phase transformation of W from β to α. The bias eff ect on the formation of α-phase Wand fi lm resistivity became more pronounced as pressure increased.