Annealing effects on the structural and electrical properties of sputtered tungsten thin films

Publication date: Available online 13 October 2016
Source:Thin Solid Films
Author(s): Andreas Kaidatzis, Vassilios Psycharis, Konstantina Mergia, Dimitrios Niarchos
We report on the structural and electrical characterization of sputter-deposited tungsten (W) films, having thicknesses between 1.5 and 100nm, before and after annealing in the temperature range between 200 and 800°C. In the as-deposited the β-W phase prevails, for all the thicknesses studied. A β-W to α-W transition occurs upon annealing at a temperature that depends on film thickness and it is accompanied by a corresponding resistivity drop. Films with thickness lower or equal to 8nm are composed predominately of β-W phase after annealing at 300°C, while the α-W phase prevails after annealing at 450°C. Films with thickness higher or equal to 10nm remain at the β-W phase after annealing at 200°C, but the α-W phase prevails after annealing at 300°C. The resistivity behavior as a function of film thickness and annealing temperature are discussed. The minimum film resistivity is obtained for the 100nm thick film after annealing at 800°C and it is 17.0μΩ ⋅cm.