Leakage-proof polishing pad and process for preparing the same

1. A polishing pad, which comprises:

a polishing layer having a first penetrating hole;

a support layer disposed under the polishing layer; and

a window disposed in the first penetrating hole,

wherein the support layer comprises a first compressed region disposed in a region corresponding to an outer peripheral region of the window and a second compressed region disposed in a region corresponding to an inner peripheral region of the window,

wherein the second compressed region is disposed to support a lower surface of the window, and

wherein a compressed portion of the support layer is provided to the second compressed region.

2. The polishing pad of claim 1 , wherein the support layer comprises a non-compression region in a region excluding the first compressed region or the second compressed region.

3. The polishing pad of claim 2 , wherein the first compressed region and the second compressed region have a density greater than the density of the non-compression region.

4. The polishing pad of claim 2 , wherein the first compressed region and the second compressed region have a thickness smaller than the thickness of the non-compression region.

5. The polishing pad of claim 2 , wherein the upper side of the second compressed region is disposed further below the upper side of the non-compression region, and the difference in height between the upper side of the second compressed region and the upper side of the non-compression region is 0.1 mm to 1.0 mm.

6. The polishing pad of claim 1 , wherein the lower side of the first compressed region has a round portion, and the radius of curvature of the round portion is 0.01 mm to 1 mm.

7. The polishing pad of claim 1 , wherein the support layer comprises a second penetrating hole connected to the first penetrating hole, and the second penetrating hole has an area smaller than the area of the first penetrating hole.

8. The polishing pad of claim 1 , wherein the thickness of the window is greater than the thickness of the polishing layer.

9. The polishing pad of claim 1 , wherein at least a part of the lower side of the window is disposed further below the lower side of the polishing layer, and the difference in height between the lower side of the polishing layer and the lower side of the window is 0.1 mm to 1.0 mm.

10. The polishing pad of claim 1 , wherein the upper side of the window is as high as the upper side of the polishing layer or is lower than the upper side of the polishing layer.

11. The polishing pad of claim 10 , wherein the upper side of the window is disposed further below the upper side of the polishing layer, and the difference in height between the upper side of the polishing layer and the upper side of the window is 0.001 mm to 0.05 mm.

12. The polishing pad of claim 1 , which further comprises a first adhesive layer disposed between the window and the support layer and between the polishing layer and the support layer.

13. The polishing pad of claim 12 , which further comprises a first adhesive layer disposed between the polishing layer and the support layer, between the lateral side of the window and the support layer, and between the lower side of the window and the upper side of the second compressed region.

14. The polishing pad of claim 12 , which further comprises a second adhesive layer disposed on one side of the window in contact with the second compressed region.

15. The polishing pad of claim 14 , wherein the thickness of the first adhesive layer and the thickness of the second adhesive layer are 20 μm to 30 μm.

16. The polishing pad of claim 1 , wherein the thickness of the polishing layer is 1.5 mm to 2.5 mm,

the thickness of the support layer is 1.0 mm to 1.5 mm, and

the thickness of the window is 2.0 mm to 3.0 mm.

17. The polishing pad of claim 1 , wherein the window comprises a recess on the lower side thereof, wherein the depth of the recess is 0.1 mm to 2.5 mm.

18. A process for preparing a polishing pad, which comprises:

(1) preparing a polishing layer having a first penetrating hole;

(2) adhering a support layer to the lower side of the polishing layer;

(3) inserting a window into the first penetrating hole; and

(4) (4-1) pressing the lower side of the support layer to form a first compressed region in a region of the support layer that corresponds to the outer peripheral region of the window, and (4-2) pressing a portion of the support layer with the window to form a second compressed region in a region of the support layer that corresponds to the inner peripheral region of the window,

wherein the second compressed region is disposed in a region facing a lower surface of the window.

19. The process for preparing a polishing pad of claim 18 , which further comprises forming a second penetrating hole connected to the first penetrating hole and having an area smaller than the area of the first penetrating hole.

20. The process for preparing a polishing pad of claim 19 , wherein the round portion is in direct or indirect contact with the lower side of the support layer to press it.

21. The process for preparing a polishing pad of claim 18 , wherein the step (4) comprises the step (4-1) of forming the first compressed region, and in the step (4-1) of forming the first compressed region, the lower side of the support layer is pressed by a pressing member that comprises a round portion.