A semiconductor device includes a gate electrode buried in a gate trench of a first conductivity-type semiconductor layer, a first conductivity-type source region, a second conductivity-type channel region, and a first conductivity-type drain region formed in the semiconductor layer, a second trench selectively formed in a source portion defined in a manner containing the source region in the surface of the semiconductor layer, a trench buried portion buried in the second trench, a second conductivity-type channel contact region selectively disposed at a position higher than that of a bottom portion of the second trench in the source portion, and electrically connected with the channel region, and a surface metal layer disposed on the source portion, and electrically connected to the source region and the channel contact region.

A manufacturing method of a semiconductor device includes preparing a semiconductor substrate having an upper surface and a lower surface, forming a first mask having a plurality of openings on the upper surface divided into a first region and a second region, forming a second mask that exposes a portion of the first mask arranged in the first region and covers a portion arranged in the second region, etching the semiconductor substrate in the first region using the first mask and the second mask as a mask, removing the second mask, and etching the semiconductor substrate in the first region and the second region using the first mask as a mask.

Disclosed is a method for fabricating a semiconductor device that improves a Self-Aligned Contact (SAC) margin by applying a wave-shaped buried gate. The method includes forming an isolation layer over a substrate and active regions defined by the isolation layer, forming a first hard mask pattern having a protrusion extending in a first direction over the substrate and overlapping with both ends of the active regions, forming a trench having a plurality of concave portions crossing the active regions and the isolation layer in the first direction and overlapping with the active regions by etching the substrate, and forming a buried gate structure to gap-fill the trench. The active regions are disposed in a first direction and a second direction orthogonal to the first direction and tilted in a third direction diagonal to the first and second directions.

A method for manufacturing a semiconductor device according to an embodiment has a first film formation step, a second film formation step, and an oxidizing step. In the first film formation step, a first coating film made of silicon is formed on a surface of a base material made of silicon carbide. In the second film formation step, a second coating film is formed on a surface of the first coating film. In the oxidizing step, the first coating film is thermally oxidized from a surface side to form a third coating film. In the second film formation step, on a part of the first coating film, the second coating film is not formed, and the part is exposed. Alternatively, in the second film formation step, a film thickness of the second coating film formed on the part of the first coating film is smaller than a film thickness of the second coating film formed on a different part.

According to an embodiment, a semiconductor device includes a first electrode, and a gate electrode, first and second insulating portions, and a second electrode. The semiconductor portion has a trench that extends along a first direction. The semiconductor portion includes first to third semiconductor layers. The gate electrode is disposed in the trench so as to face the second semiconductor layer and the third semiconductor layer along a second direction orthogonal to the first direction. The gate electrode has a facing surface formed at a position facing the third semiconductor layer so as to be away from the third semiconductor layer as the facing surface extends upward. The first insulating portion is continuously provided on the semiconductor portion and inside the trench. The second insulating portion is provided on the gate electrode. A material of the second insulating portion is different from a material of the first insulating portion.