Methods of manufacturing a semiconductor device are provided. The methods may include forming a fin-type active region protruding from a substrate and forming a gate insulating film covering a top surface and both sidewalls of the fin-type active region. The gate insulating film may include a high-k dielectric film. The methods may also include forming a metal-containing layer on the gate insulating film, forming a silicon capping layer containing hydrogen atoms on the metal-containing layer, removing a portion of the hydrogen atoms contained in the silicon capping layer, removing the silicon capping layer and at least a portion of the metal-containing layer, and forming a gate electrode on the gate insulating film. The gate electrode may cover the top surface and the both sidewalls of the fin-type active region.