Methods and structures for improving alignment contrast for patterning a metal layer generally includes depositing a metal layer having a plurality of grains, wherein grain boundaries between the grains forms grooves at a surface of the metal layer. The metal layer is subjected to surface treatment to form an oxide or a nitride layer and fill the surface grooves. The metal layer can be patterned using alignment marks in the metal layer and/or underlying layers. Filling the grooves with the oxide or nitride increases alignment contrast relative to patterning the metal layer without the surface treating.