An optoelectronic device comprises a semiconductor stack, a first metal layer formed above the semiconductor stack, wherein the first metal layer comprises a first major plane and a first boundary with a gradually reduced thickness, and a second metal layer formed above the first metal layer, wherein the second metal layer comprise a second major plane paralleling to the first major plane and a second boundary with a gradually reduced thickness, and the second boundary of the second metal layer exceeds the first boundary of the first metal layer.