CMP pad having overlaid constant area spiral grooves
View Patent ↗A circular chemical mechanical polishing pad that includes a polishing surface having a concentrically located origin. The polishing surface includes groove sets each containing grooves arranged in a pattern in which ones of the grooves in one groove set cross ones of the grooves in another set. The grooves in each groove set are configured and arranged so that the fraction of the polishing surface that is grooved, as measured along any circle that is concentric with the origin and crosses the grooves, is substantially constant, i.e., within about 25% of its average.
1. A polishing pad, comprising:
a polishing layer configured for polishing at least one of a magnetic, optical and semiconductor substrate in the presence of a polishing medium, the polishing layer including a circular polishing surface having a concentric center and an outer periphery;
at least one first groove formed in the circular polishing surface; and
a groove set formed in the circular polishing surface so as to cross the at least one first groove at least twice so as to define at least one four-sided landing having four curved sides;
wherein each of the at least one first groove and the at least one second groove provide the circular polishing surface with a respective circumference fraction grooved from a first location proximate the concentric center to a second location proximate the outer periphery, the respective circumference fraction grooved having an average and remaining within about 25% of the average.
2. The polishing pad according to claim 1 , wherein the at least one first groove has a first starting radius and a first spiral shape defined by a set of constant circumference fraction grooved equations as a function of the first starting radius and the groove set has a second starting radius and a second spiral shape defined by the set of constant circumference fraction grooved equations as a function of the second starting radius.
3. The polishing pad according to claim 2 , wherein the polishing surface has an annular wafer track when the polishing pad is used for polishing, the first starting radius being located between the concentric center of the polishing surface and the wafer track and the second starting radius lying within the wafer track.
4. The polishing pad according to claim 2 , wherein the at least one first groove winds in a first direction about the concentric center of the circular polishing surface and the groove set winds in a second direction about the concentric center opposite the first direction.
5. The polishing pad according to claim 1 , further comprising a plurality of first grooves providing the respective constant circumference fraction grooves, the plurality of first grooves having a varied angular pitch among the plurality of first grooves.
6. The polishing pad according to claim 1 , wherein the circumference fraction grooved of each of the at least one first groove and the groove set has an average and remains within about 10% of the average.
7. A polishing pad, comprising:
a polishing layer configured for polishing at least one of a magnetic, optical and semiconductor substrate in the presence of a polishing medium, the polishing layer including a circular polishing surface having a concentric center and an outer periphery;
a first groove set having a first starting radius and containing a plurality of first grooves formed in the circular polishing surface, each of the plurality of first grooves laid out in accordance with a set of constant circumference fraction grooved equations as a function of the first starting radius so as to provide a first circumference fraction grooved having a first average and remaining within about 5% of the first average; and
a second groove set having a second staring radius and containing a plurality of second grooves formed in the circular polishing surface so that ones of the plurality of first grooves cross ones of the plurality of second grooves at least once so as to define a plurality of four-sided landings each having four curved sides, each of the plurality of second grooves laid out in accordance with the set of constant circumference fraction grooved equations as a function of the second starting radius so as to provide a second circumference fraction grooved having a second average and remaining within about 5% of the second average.
8. The polishing pad according to claim 7 , wherein said first starting radius is less than about 1/12 of the pad outer radius in order to provide each spiral groove in the first groove set with at least two full turns.
9. The polishing pad according to claim 8 , wherein said second starting radius is greater than about ⅓ of the pad outer radius in order to provide each spiral groove in the second groove set with no more than one full turn.
10. The polishing pad according to claim 8 , wherein said second starting radius is less than about 1/12 of the pad outer radius in order to provide each spiral groove in the second groove set with at least two full turns.