A method of manufacturing a semiconductor device includes forming an insulating pattern layer on a substrate, conformally forming a first conductive layer with a first thickness on the insulating pattern layer, wet etching the first conductive layer to have a second thickness that is less than the first thickness, and forming a second conductive layer on the first conductive layer after wet etching the first conductive layer. The second conductive layer includes a material that is different from a material included in the first conductive layer.