Semiconductor device and method for manufacturing the same

1. A method for manufacturing a semiconductor device, the method comprising:

sequentially stacking a first epitaxial layer, a sacrificial layer, a second epitaxial layer, and a third epitaxial layer on a first substrate;

forming a trench which penetrates the third epitaxial layer, the second epitaxial layer, and the sacrificial layer;

forming a structure layer on an upper surface of the third epitaxial layer;

forming a metal film which covers an inner surface of the trench and the structure layer;

forming a second substrate which fills the trench and covers the metal film; and

separating the second epitaxial layer, the third epitaxial layer, and the structure layer from the first epitaxial layer.

2. The method of claim 1 , wherein the separating the second epitaxial layer, the third epitaxial layer, and the structure layer comprises:

providing a stress to the sacrificial layer; and

separating the second epitaxial layer from the first epitaxial layer,

wherein propagation of a crack starts, due to the stress, at one end of the sacrificial layer which contacts the metal film,

wherein the crack progresses along the sacrificial layer.

3. The method of claim 1 , wherein the trench is provided in plurality,

wherein device parts are defined by the trenches,

wherein each trench comprises a part of the second epitaxial layer, a part of the third epitaxial layer, and a part of the structure layer.

4. The method of claim 3 , wherein, during a process of separating the second epitaxial layer, the third epitaxial layer, and the structure layer, only a portion of the device parts is separated.

5. The method of claim 1 ,

wherein the sacrificial layer has a lattice constant different from lattice constants of the first epitaxial layer and the second epitaxial layer,

wherein the sacrificial layer has lattice matching with the first epitaxial layer and the second epitaxial layer at interfaces with the first epitaxial layer and the second epitaxial layer.

6. The method of claim 5 ,

wherein the sacrificial layer comprises In 0.17 Al 0.83 N,

wherein the first and second epitaxial layers comprise gallium nitride (GaN).

7. The method of claim 1 , wherein a bottom surface of the trench has a width larger than that of an upper end of the trench.

8. The method of claim 7 , wherein the trench increases in width in a direction from the third epitaxial layer to the sacrificial layer.

9. The method of claim 1 ,

wherein the metal film covers a sidewall and a bottom surface of the trench,

wherein the second substrate is spaced apart from the sidewall and the bottom surface of the trench.