Semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device, comprising:

• forming a first electrode layer, a semiconductor layer comprising at least germanium, and a second electrode layer at a side of a substrate in the above-listed sequence, wherein the first electrode layer serves as one of a source layer and a drain layer, and the second electrode layer serves as another of the source layer and the drain layer;
• removing a part of the semiconductor layer through etching a sidewall of the semiconductor layer to form a cavity, wherein the cavity comprises a concave facing a distal side of the semiconductor device;
• forming a channel layer at the cavity, a sidewall of the first electrode layer, and a sidewall of the second electrode layer, wherein the channel layer comprises a first channel part located in the cavity and a second channel part located outside the cavity, and the first channel part is conformed to the cavity;
• filling the first channel part with a dummy gate layer, wherein a sidewall of the dummy gate layer is flush with a sidewall of the second channel part;
• removing a part of the dummy gate layer through etching the sidewall of the dummy gate layer, wherein a sidewall of the etched dummy gate layer is flush with the sidewall of the first electrode layer;
• removing the second channel part and the first channel part that is in contact with an upper surface and a lower surface of the dummy gate layer to form a recess, wherein the recess is formed by either the first electrode layer or the second electrode layer, the channel layer, and the dummy gate layer;
• and
• filling the recess with a dielectric material to form an isolation sidewall.