Conductive structure, redistribution structure and forming method thereof

The present disclosure provides methods and structures to prevent cracks in redistribution layers. A redistribution structure according to the present disclosure includes a first polymer layer disposed over a silicon substrate, a first contact via disposed in the first polymer layer, a second polymer layer disposed over the first contact via, a first redistribution layer including a first conductive pad disposed on the second polymer layer and a second contact via extending through the second polymer layer to physical contact the first contact via, a third polymer layer disposed over the first redistribution layer, a second redistribution layer including a second conductive pad disposed on the third polymer layer and a plurality of third contact vias extending through the third polymer layer to physically contact the first conductive pad. The first conductive pad has at least one opening and the second conductive pad has at least one opening.