CMP pad having an overlapping stepped groove arrangement
View Patent ↗A polishing pad ( 104, 300 ) having an annular polishing track ( 152, 320 ) and a plurality of groups ( 160, 308 ) of grooves ( 112, 304 ) repeated circumferentially about the rotational center ( 128 ) of the pad. The plurality of grooves in each group are arranged along a trajectory ( 164, 312 ) in an offset and overlapping manner so as to provide a plurality of overlapping steps ( 172, 316 ) within the annular polishing track. The groups may be arranged in spaced-apart or nested relation with one another.
1. A polishing pad, comprising:
a) a polishing layer configured to polish a surface of at least one of a magnetic, optical or semiconductor substrate in the presence of a polishing medium, the polishing layer including a rotational axis and an annular polishing track concentric with the rotational axis; and
b) a plurality of grooves formed in the polishing layer and arranged into a plurality of groups of at least three grooves each along a trajectory that extends through the annular polishing track, wherein the at least three grooves of the plurality of grooves within each group form an overlapping stepped pattern of at least two overlapping steps within the annular polishing truck for forming a discontinuous flow path along the trajectory.
2. The polishing pad according to claim 1 , wherein the plurality of groups are spaced from one another in a circumferential direction about the rotational axis.
3. The polishing pad according to claim 1 , wherein the plurality of groups are nested with one another in a circumferential direction about the rotational axis.
4. The polishing pad according to claim 1 , wherein the annular polishing track has a width and each groove in each of the plurality of grooves has a length shorter than the width of the annular polishing track.
5. The polishing pad according to claim 1 , wherein the trajectory of each of the plurality of groups is arcuate.
6. The polishing pad according to claim 5 , wherein the polishing pad has a design rotational direction and the trajectory of each of the plurality of groups is curved in the design rotational direction.
7. A polishing pad, comprising:
a) a polishing layer configured to polish a surface of at least one of a magnetic, optical or semiconductor substrate in the presence of a polishing medium, the polishing layer including a rotational axis and an annular polishing track concentric with the rotational axis; and
b) a plurality of grooves formed in the polishing layer and arranged into a plurality of groups of at least three grooves each along a trajectory that extends through the annular polishing track, wherein the at least three grooves (N ≧ 3) of the plurality of grooves within each group form an overlapping stepped pattern of N−1 steps within the annular polishing track for forming a discontinuous flow path along the trajectory.
8. The polishing pad of claim 7 , wherein ones of the plurality of grooves within each group form at least two overlapping steps within the annular polishing track.
9. The polishing pad of claim 7 , wherein the pad further comprises a peripheral edge and the annular polishing track includes an inner circular boundary, the polishing layer further including a central region defined by the inner circular boundary of the annular polishing track, and a peripheral region located between the annular polishing track and the peripheral edge of the pad, each of the plurality of groups including an inner groove present only in the central region and the annular polishing track and an outer groove present only in the annular polishing track and the peripheral region.
10. The polishing pad of claim 7 , wherein the annular polishing track has a width and each groove in each of the plurality of grooves has a length shorter than the width of the annular polishing track.