Bush insert, bush assembly including the same and upper electrode assembling structure including the same

1 . A bush insert coupled to a plasma electrode plate,

wherein the bush insert is configured to provide an insert inner hole that passes through the bush insert in a first direction,

an inner surface of the bush insert that defines the insert inner hole is configured to provide a female screw structure, and

an outer surface of the bush insert has a non-circular shape in a plan view,

wherein the bush insert further comprises a shrinkage hole extending from the insert inner hole in a horizontal direction crossing the first direction and connected to the outer surface of the bush insert,

wherein a length of the shrinkage hole in the first direction is less than a length of the insert inner hole in the first direction.

2 . The bush insert of claim 1 , wherein the insert inner hole comprises:

a second inner hole recessed downward from a top surface of the bush insert; and

a first inner hole extending downward from the second inner hole and connected to a bottom surface of the bush insert,

wherein the inner surface of the bush insert includes a first inner surface and a second inner surface, and the female screw structure is provided on the first inner surface of the bush insert that defines the first inner hole.

3 . The bush insert of claim 2 , wherein the first inner hole has a circular shape in the plan view.

4 . The bush insert of claim 1 , wherein the outer surface of the bush insert comprises:

a first outer surface parallel to the first direction;

a second outer surface disposed at an opposite side of the first outer surface based on the insert inner hole;

a third outer surface between the first outer surface and the second outer surface; and

a fourth outer surface disposed at an opposite side of the third outer surface based on the insert inner hole,

wherein each of the first outer surface, the second outer surface, the third outer surface, and the fourth outer surface has a plane shape.

5 . The bush insert of claim 4 , wherein the outer surface of the bush insert further comprises a first curved surface configured to connect the second outer surface to the third outer surface.

6 . An upper electrode assembling structure comprising:

a first electrode plate; and

a bush assembly coupled to the first electrode plate,

wherein the first electrode plate is configured to provide a first insertion hole that is recessed to a predetermined depth downward from a top surface of the first electrode plate, and

the bush assembly comprises:

a bush; and

a bush insert coupled to the bush so as to surround the bush,

wherein each of the first insertion hole and the bush insert has a rounded square shape in a plan view, and

the bush insert is inserted into the first insertion hole.

7 . The upper electrode assembling structure of claim 6 , further comprising a second electrode plate on the first electrode plate.

8 . The upper electrode assembling structure of claim 6 , wherein the bush insert is configured to provide an insert inner hole that vertically passes through the bush insert,

wherein an inner surface of the bush insert that defines the insert inner hole is configured to provide a female screw structure, and

the bush is screw-coupled to the female screw structure.

9 . The upper electrode assembling structure of claim 8 , wherein the insert inner hole has a circular shape in the plan view.

10 . The upper electrode assembling structure of claim 8 , wherein the insert inner hole comprises:

a second inner hole recessed downward from a top surface of the bush insert; and

a first inner hole extending downward from the second inner hole and connected to a bottom surface of the bush insert,

wherein the second inner hole has a width greater than a width of the first inner hole.

11 . The upper electrode assembling structure of claim 8 , wherein the bush insert is configured to further provide a shrinkage hole extending from the insert inner hole in a horizontal direction crossing a first direction and connected to an outer surface of the bush insert.

12 . The upper electrode assembling structure of claim 11 , wherein a length of the shrinkage hole in the first direction is less than a length of the insert inner hole in the first direction,

wherein the shrinkage hole is connected to a bottom surface of the bush insert.

13 . The upper electrode assembling structure of claim 11 , wherein the shrinkage hole comprises four shrinkage holes,

wherein the four shrinkage holes are defined to be spaced apart from each other in a circumferential direction.

14 . A bush assembly comprising:

a bush insert; and

a bush inserted into the bush insert,

wherein the bush is configured to provide an internal through-hole that passes through the bush in a first direction,

a male screw structure is provided on an outer surface of the bush,

the bush insert is configured to provide an insert inner hole that passes through the bush insert in the first direction,

an inner surface of the bush insert that defines the insert inner hole is configured to a female screw structure engaged with the male screw structure,

an outer surface of the bush insert has a non-circular shape in a plan view, and

an outer surface of the bush has a circular shape in the plan view.

15 . The bush assembly of claim 14 , wherein the outer surface of the bush insert has a rounded square shape in the plan view.

16 . The bush assembly of claim 14 , wherein the bush insert is configured to further provide a plurality of shrinkage holes extending from the insert inner hole in a horizontal direction crossing the first direction and connected to the outer surface of the bush insert.

17 . The bush assembly of claim 14 , wherein the insert inner hole comprises:

a second inner hole recessed downward from a top surface of the bush insert; and

a first inner hole extending downward from the second inner hole and connected to a bottom surface of the bush insert.