Pre-treatment study for barrier-less Ruthenium filling into single damascene via of sub 20nm hole size

Ru filling in small vias is challenging. Voids in the via will cause high via resistance. Ru filling with dep-etch sequence helps to minimize void formation; however, it is not productivity friendly. We report Ru fill without void in sub 20nm diameter vias using a surface treatment. New surface treatment has been introduced as a treatment to manage the Ru deposition rate on SiO2 and the bottom metal.