Method of manufacturing grooved chemical mechanical polishing layers

1. A method of manufacturing a polishing layer with a grooved polishing surface for use in a chemical mechanical polishing pad; wherein the method comprises:

providing a polishing layer with an ungrooved polishing surface, wherein providing the polishing layer with an ungrooved polishing surface comprises:

providing a mold, having a mold base and a surrounding wall attached to the mold base;

providing a liner with a top surface, a bottom surface and an average thickness of 2 to 10 cm;

providing an adhesive;

providing a curable material comprising a liquid prepolymer and a plurality of microelements;

providing a nozzle, having a nozzle opening;

providing a skiver blade with a cutting edge;

providing a strop;

providing a stropping compound;

bonding the bottom surface of the liner to the mold base using the adhesive,

wherein the top surface of the liner and the surrounding wall define a mold cavity;

wherein the top surface of the liner defines a horizontal internal boundary of the mold cavity, wherein the horizontal internal boundary of the mold is oriented along an x-y plane, wherein the mold cavity has a central axis, C axis , that is perpendicular to the x-y plane, and wherein the mold cavity has a doughnut hole region and a doughnut region;

charging the curable material through the nozzle opening to the mold cavity during a charging period, CP, wherein the charging period, CP, is broken down into three separate phases identified as an initial phase, a transition phase and a remainder phase;

wherein the nozzle opening has a location and wherein the location of the nozzle opening moves relative to mold base along the mold cavity's central axis, C axis , during the charging period, CP, to maintain the location of the nozzle opening above a top surface of the curable material in the mold cavity as the curable material collects in the mold cavity;

wherein the location of the nozzle opening resides within the doughnut hole region throughout the initial phase; wherein the location of the nozzle opening transitions from residing within the doughnut hole region to residing within the doughnut region during the transition phase; and, wherein the location of the nozzle opening resides within the doughnut region during the remainder phase;

wherein the mold cavity approximates a right cylindrically shaped region having a substantially circular cross section, C x-sect ; wherein the mold cavity has an axis of symmetry, C x-sym , which coincides with the mold cavity's central axis, C axis ; wherein the right cylindrically shaped region has a cross sectional area, C x-area , defined as follows:

C x-area =πr C 2 ,

wherein r C is the average radius of the mold cavity's cross sectional area, C x-area , projected onto the x-y plane; wherein the doughnut hole region is a right cylindrically shaped region within the mold cavity that projects a circular cross section, DH x-sect , onto the x-y plane and has an axis of symmetry, DH axis ; wherein the doughnut hole has a cross sectional area, DH x-area , defined as follows:

DH x-area =πr DH 2 ,

wherein r DH is a radius of the doughnut hole region's circular cross section, DH x-sect ;

wherein the doughnut region is a toroid shaped region within the mold cavity that projects an annular cross section, D x-sect , onto the x-y plane and that has a doughnut region axis of symmetry, D axis ; wherein the annular cross section, D x-sect , has a cross sectional area, D x-area , defined as follows:

D x-area =πR D 2 −πr D 2

wherein R D is a larger radius of the doughnut region's annular cross section, D x-sect ;

wherein r D is a smaller radius of the doughnut region's annular cross section, D x-sect ;

wherein r D ≧r DH ; wherein R D >r D ; wherein R D <r C ; wherein each of the C x-sym , the DH axis and the D axis are perpendicular to the x-y plane;

allowing the curable material in the mold cavity to cure into a cake, wherein the curable material bonds to the liner;

separating the surrounding wall from the mold base and the cake;

applying the stropping compound to the cutting edge;

stropping the skiver blade with the strop; and, slicing the cake to provide the polishing layer with an ungrooved polishing surface using the skiver blade;

first machining at least one curved groove into the ungrooved polishing surface; and,

then machining a plurality of linear grooves in an XY grid pattern into the polishing surface to produce the polishing layer with a grooved polishing surface;

wherein the plurality of linear grooves are machined by a step down process, wherein a groove cutting tool makes multiple successive cutting passes to form each linear groove, and, wherein each successive cutting pass increases the depth of the linear groove being formed.