Polishing pad with multipurpose composite window
The invention provides a polishing pad suitable for polishing integrated circuit wafers. It includes an upper polishing layer that having a polishing surface and at least one groove in the upper polishing layer. At least one transparent window is located within the upper layer. The at least one transparent window has a thickness greater than a desired wear depth of the at least one groove. The at least one transparent window includes a non-fluorescent transparent polymer; and a fluorescent transparent polymer. The transparent window allows measuring groove depth by activating the fluorescent transparent polymer with an activation source at a wavelength sufficient to excite the fluorescent transparent polymer and allow endpoint detection by sending light through the fluorescent transparent polymer and the non-fluorescent transparent polymer.
1. A polishing pad suitable for polishing integrated circuit wafers comprising:
an upper polishing layer that contacts an article to be polished, the upper polishing layer having a polishing surface;
at least one groove in the upper polishing layer, the at least one groove extending downward from the polishing surface of said upper polishing layer, the at least one groove having a depth,
at least one transparent window located within the upper layer, the at least one transparent window having a thickness greater than a desired wear depth of the at least one groove, the at least one transparent window including:
a non-fluorescent transparent polymer; and
a fluorescent transparent polymer; wherein the transparent window allows measuring groove depth by activating the fluorescent transparent polymer with an activation source at a wavelength sufficient to excite the fluorescent transparent polymer and allows endpoint detection by sending light through the fluorescent transparent polymer and the non-fluorescent transparent polymer.
2. The polishing pad of claim 1 wherein a boundary interface separates the non-fluorescent transparent polymer from the fluorescent transparent polymer.
3. The polishing pad of claim 2 wherein the boundary interface is parallel to the polishing surface of the polishing pad.
4. The polishing pad of claim 2 wherein the boundary interface is at an angle to the polishing surface of the polishing pad for continuous determination of pad wear.
5. The polishing pad of claim 2 wherein the boundary interface has an end location of less than or equivalent to the depth of the at least one groove.
6. The polishing pad of claim 1 wherein the fluorescent transparent polymer includes a fluorescent moiety and the fluorescent moiety is chemically linked to a transparent polymer.
7. The polishing pad of claim 1 wherein the fluorescent moiety contains an acrylate linking group.
8. The polishing pad of claim 1 wherein the fluorescent moiety contains a methacrylate linking group.
9. A polishing pad of claim 1 wherein the fluorescent transparent polymer wears at a rate equal to the non-fluorescent transparent polymer and the fluorescent transparent polymer includes at least one fluorescent moiety selected from 2-naphthyl acrylate; 9-anthracenyl methyl methacrylate; and 1-pyrenyl methyl methacrylate.