Semiconductor device and method

A device comprising:

• a substrate comprising a first opening, the first opening comprising a first region and a second region, wherein the first region extends from a surface of the substrate to a first depth in the substrate, wherein the second region extends from the first depth through the substrate, wherein the substrate comprises:
• a plurality of first scallops adjacent the first region of the first opening, the first scallops extending to a second depth;
• and
• a plurality of second scallops adjacent the second region of the first opening, the second scallops extending to a third depth greater than the second depth;
• and
• a metal layer extending along side surfaces of the substrate in the first opening, wherein a conductivity of the metal layer in the first region of the first opening is greater than a conductivity of the metal layer in the second region of the first opening.