According to one or more embodiments, a method for manufacturing a semiconductor device includes alternately stacking a first film and a second film on an object to form a multilayer film, then forming a stacked body and a recess by partially removing the multilayer film. A dielectric layer is then formed by applying a composite material to the recess to fill the recess with the dielectric layer. The composite material includes an inorganic material and an organic material. The dielectric layer is then exposed to an oxidizing gas to oxidize the inorganic material and to remove at least part of the organic material from the dielectric layer.