METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

A method for manufacturing a semiconductor device including steps as follows is provided. A first nitride-based semiconductor layer is formed over a substrate. A second nitride-based semiconductor layer is formed on the first nitride-based semiconductor layer. A gate electrode is formed over the second nitride-based semiconductor layer. A first passivation layer is formed on the second nitride-based semiconductor layer to cover the gate electrode. A first blanket field plate is formed on the first passivation layer. The first blanket field plate is patterned to form a first field plate above the gate electrode using a wet etching process. A second passivation layer is formed on the first passivation layer to cover the first field plate. A second blanket field plate is formed on the second passivation layer. The second blanket field plate is patterned to form a second field plate above the first field plate using a dry etching process.