ENDPOINT WINDOW WITH CONTROLLED TEXTURE SURFACE
A chemical mechanical polishing pad window having a controlled texture surface comprising repeated patterned features. The window results in an improved endpoint detection and in situ rate monitoring by providing consistent values of the ISRM max-min characteristic over the lifetime of a CMP pad. Also provided is a chemical mechanical polishing pad with the inventive window.
1 . A chemical mechanical planarization (CMP) pad comprising:
a top pad portion and a subpad portion;
a window comprising a material transmissive to light, wherein a first surface of the window has a controlled texture surface comprising repeated patterned features;
the window being attached to the top pad portion of the CMP pad within a recess, wherein the recess does not form an aperture through the top pad, and the recess has a hole extending through the top pad portion and the subpad portion at the recess, whereas the dimension of the hole is such that a ledge is formed by the remaining top pad portion and the underlying subpad portion and wherein the window is attached to the top pad portion of the ledge on top of the hole.
2 . The CMP pad of claim 1 , wherein the repeated patterned features comprise regularly spaced raised features.
3 . The CMP pad of claim 2 , wherein the repeated patterned features comprise a crosshatch pattern.
4 . The CMP pad of claim 1 , wherein the repeated patterned features are configured to diffuse light passing through the window.
5 . The CMP pad of claim 1 , wherein the repeated patterned features comprise rounded ridges.
6 . The CMP pad of claim 5 , wherein the rounded ridges are randomly roughened.
7 . The CMP pad of claim 5 , wherein the window has a width and a length that is less than the width, wherein the width and the length characterize physical dimensions of the window and wherein the recess has a width and a length that characterize the physical dimensions of the recess.
8 . The CMP pad of claim 7 , wherein the physical dimensions of the recess align with the physical dimensions of the window.
9 . A method of attaching a window to a chemical-mechanical (CMP) polishing pad comprising:
in the polishing pad having a top pad portion and a subpad portion, and the top pad portion having a thickness, forming a recess in the top pad portion of the polishing pad such that the recess does not extend the entire thickness of the top pad;
forming a hole through the top pad portion and the subpad portion at the recess, whereas the dimension of the hole is such that a ledge is formed by the remaining top pad portion material;
attaching a window comprising a material transmissive to light, in the recess, on top of the hole, forming an optical detection port, wherein a first surface of the window has a controlled texture surface comprising repeated patterned features.
10 . The method of claim 9 , wherein the repeated patterned features comprise regularly spaced raised features.
11 . The method of claim 9 , wherein the repeated patterned features comprise a crosshatch pattern.
12 . The method of claim 9 , wherein the repeated patterned features are configured to diffuse light passing through the window.
13 . The method of claim 9 , wherein the repeated patterned features comprise rounded ridges.
14 . The method of claim 13 , wherein the rounded ridges are randomly roughened.
15 . The method of claim 9 , wherein the window is attached using an adhesive.
16 . The method of claim 9 , wherein the window is attached without the use of an adhesive.