A semiconductor device has a substrate and first conductive layer formed over the substrate. An insulating layer is formed over the first substrate with an opening over the first conductive layer. A second conductive layer is formed within the opening of the insulating layer. A portion of the second conductive layer is removed to expose a horizontal surface and side surfaces of the second conductive layer below a surface of the insulating layer. The second conductive layer has non-linear surfaces to extend a contact area of the second conductive layer. The horizontal surface and side surfaces can be stepped surfaces or formed as a ring. A third conductive layer is formed over the second conductive layer. A plurality of bumps is formed over the horizontal surface and side surfaces of the second conductive layer. A semiconductor die is mounted to the substrate.