Chemical mechanical polishing pads having offset circumferential grooves for improved removal rate and polishing uniformity
View Patent ↗The present invention provides a chemical mechanical (CMP) polishing pad for planarizing at least one of semiconductor, optical and magnetic substrates comprising a polishing layer that has a geometric center, and in the polishing layer a plurality of offset circumferential grooves, such as circular or polygonal grooves, which have a plurality of geometric centers and not a common geometric center. In the polishing layer of the present invention, each circumferential groove is set apart a pitch distance from its nearest or adjacent circumferential groove or grooves; for example, the pitch increases on the half or hemisphere of the polishing layer that is farthest from the geometric center of its innermost circumferential groove and decreases on the half of the polishing layer nearest that geometric center. Preferably, the polishing layer contains an outermost circumferential groove that is complete and continuous.
1. A chemical mechanical polishing pad for planarizing at least one of semiconductor, optical and magnetic substrates comprises a polishing layer that has a geometric center, the polishing layer containing a plurality of offset circumferential grooves that have a plurality of geometric centers, each circumferential groove being set apart a pitch distance from its nearest or adjacent circumferential groove or grooves and most circumferential grooves having a geometric center that is different than its adjacent circumferential groove and wherein when going from an innermost circumferential groove to an outermost circumferential groove, relative location of the geometric center of each successive circumferential groove moves toward the geometric center of the polishing layer.
2. The CMP polishing pad as claimed in claim 1 , wherein the polishing layer contains an outermost circumferential groove that is complete and continuous and that is concentric with the polishing layer itself or has a common geometric center with and is not offset from the geometric center of the polishing layer.
3. The CMP polishing pad as claimed in claim 1 , wherein except for an innermost and an outermost circumferential groove, each of the plurality of offset circumferential grooves has two adjacent circumferential grooves.
4. The CMP polishing pad as claimed in claim 3 , wherein a majority of the offset circumferential grooves that have two adjacent circumferential grooves are offset from their respective two adjacent circumferential grooves by from 25 to 200 μm (1 to 8 mils).
5. The CMP polishing pad as claimed in claim 1 , wherein a majority of the offset circumferential grooves are offset by from 200 to 35,000 μm from the geometric center of the polishing layer.
6. The CMP polishing pad as claimed in claim 1 , wherein a majority of the offset circumferential grooves are offset by from 500 to 21,500 μm from the geometric center of the polishing layer.
7. The CMP polishing pad as claimed in claim 6 , wherein all of the offset circumferential grooves except an outermost circumferential groove are offset by from 500 to 21,500 μm from the geometric center of the polishing layer.
8. The CMP polishing pad as claimed in claim 1 , wherein each of the circumferential grooves in polishing pad is polygonal, having from 3 to 36 sides, or is substantially circular.
9. The CMP polishing pad as claimed in claim 1 , wherein the polishing layer comprises a plurality of radial grooves.