SiC semiconductor device

1. An SiC semiconductor device comprising:

an SiC semiconductor layer including an SiC monocrystal and having a first main surface as a device surface, a second main surface at a side opposite to the first main surface, and a side surface connecting the first main surface and the second main surface;

a main surface insulating layer including an insulating material, covering the first main surface of the SiC semiconductor layer, and having an insulating side surface formed flush with respect to the side surface of the SiC semiconductor layer; and

a boundary modified layer including a first region that is modified to be of a property differing from the SiC monocrystal and a second region that is modified to be of a property differing from the insulating material, and being formed across the side surface of the SiC semiconductor layer and the insulating side surface of the main surface insulating layer,

wherein the boundary modified layer is exposed outside from the side surface of the SiC semiconductor layer and the insulating side surface of the main surface insulating layer.

2. The SiC semiconductor device according to claim 1 , wherein the boundary modified layer extends in a band shape along a tangential direction to the first main surface of the SiC semiconductor layer.

3. The SiC semiconductor device according to claim 1 , wherein the boundary modified layer includes a plurality of boundary modified portions each extending in a normal direction to the first main surface of the SiC semiconductor layer and aligned such as to oppose each other in a tangential direction to the first main surface of the SiC semiconductor layer.

4. The SiC semiconductor device according to claim 1 , wherein the main surface insulating layer includes SiO2.

5. The SiC semiconductor device according to claim 1 , wherein the side surface of the SiC semiconductor layer is constituted of a cleavage surface, and the insulating side surface of the main surface insulating layer is constituted of a cleavage surface.

6. The SiC semiconductor device according to claim 1 , further comprising:

an insulating layer formed on the main surface insulating layer;

wherein the boundary modified layer is formed across the side surface of the SiC semiconductor layer and the insulating side surface of the main surface insulating layer while avoiding the insulating layer.

7. The SiC semiconductor device according to claim 6 , wherein the insulating layer is formed at an interval toward an inner side from the side surface of the SiC semiconductor layer.

8. The SiC semiconductor device according to claim 7 , wherein the insulating layer is formed at an interval of not less than 1 μm toward the inner side from the side surface of the SiC semiconductor layer.

9. The SiC semiconductor device according to claim 6 , wherein the insulating layer has a thickness of not less than 1 μm.

10. The SiC semiconductor device according to claim 6 , wherein the insulating layer includes an insulating material differing from the main surface insulating layer.

11. The SiC semiconductor device according to claim 6 , wherein the insulating layer includes a resin layer formed on the main surface insulating layer.

12. The SiC semiconductor device according to claim 6 , wherein the insulating layer includes a passivation layer formed on the main surface insulating layer.

13. The SiC semiconductor device according to claim 1 , further comprising:

a modified layer formed in a region of the side surface of the SiC semiconductor layer at the second main surface side of the SiC semiconductor layer with respect to the boundary modified layer, and being modified to be of a property differing from the SiC monocrystal.

14. The SiC semiconductor device according to claim 13 , wherein the modified layer extends in a band shape along a tangential direction to the first main surface of the SiC semiconductor layer.

15. The SiC semiconductor device according to claim 1 , wherein the SiC semiconductor layer has a thickness of not less than 40 μm and not more than 200 μm.

16. The SiC semiconductor device according to claim 1 , wherein the SiC semiconductor layer has a laminated structure that includes an SiC semiconductor substrate and an SiC epitaxial layer and in which the first main surface is formed by the SiC epitaxial layer, the main surface insulating layer is formed on the SiC epitaxial layer, and the boundary modified layer is formed across the SiC epitaxial layer and the main surface insulating layer.

17. The SiC semiconductor device according to claim 16 , wherein the SiC epitaxial layer has a thickness not more than a thickness of the SiC semiconductor substrate.

18. The SiC semiconductor device according to claim 16 , wherein the SiC semiconductor substrate has a thickness of not less than 40 μm and not more than 150 μm, and

the SiC epitaxial layer has a thickness of not less than 1 μm and not more than 50 μm.

19. The SiC semiconductor device according to claim 1 , wherein the SiC monocrystal is constituted of a hexagonal crystal, and

the first main surface of the SiC semiconductor layer faces a c-plane of the SiC monocrystal.

20. The SiC semiconductor device according to claim 19 , wherein the first main surface of the SiC semiconductor layer has an off angle inclined at an angle of not less than 0° and not more than 10° with respect to the c-plane of the SiC monocrystal.