A memory film and a semiconductor channel can be formed within each memory opening that extends through a stack including an alternating plurality of insulator layers and sacrificial material layers. After formation of backside recesses through removal of the sacrificial material layers selective to the insulator layers, a ruthenium portion can be formed in each backside recess, and a polycrystalline conductive material portion can be formed on each ruthenium portion. Each ruthenium portion can be employed in lieu of a tungsten seed layer to function as a lower resistivity seed layer that enables subsequent deposition of a polycrystalline conductive material. The resulting electrically conductive lines can have a lower resistivity than conductive lines of comparable dimensions that employ tungsten seed layers.