Method of manufacturing chemical mechanical polishing layers

1. A method of forming a polishing layer for a chemical mechanical polishing pad, comprising:

providing a mold, having a mold base and a surrounding wall, wherein the mold base and the surrounding wall define a mold cavity, wherein the mold base 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;

providing a liquid prepolymer material;

providing a plurality of microelements;

providing a nozzle, having a nozzle opening;

combining the liquid prepolymer material with the plurality of microelements to form a curable mixture;

charging the curable mixture 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 mixture in the mold cavity as the curable mixture 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;

wherein the location of the nozzle opening resides within the doughnut region during the remainder phase;

wherein the mold cavity is symmetric about the mold cavity's central axis, C axis ;

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-axis , 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 mixture in the mold cavity to cure into a cake; and,

deriving the polishing layer from the cake.

2. The method of claim 1 , wherein the mold base defines a horizontal internal boundary of the mold cavity; and wherein the horizontal internal boundary is flat.

3. The method of claim 1 , wherein the movement of the location of the nozzle opening momentarily pauses in its motion relative to the mold cavity's central axis, C axis , during the remainder phase.

4. The method of claim 1 , wherein the curable mixture is charged to the mold cavity at an essentially constant rate over the charging period, CP, with an average charging rate, CR avg of 0.015 to 2 kg/see.

5. The method of claim 1 , wherein the mold cavity is symmetric about the mold cavity's central axis, C axis .

6. The method of claim 1 , wherein R D ≦(K*r C ), wherein K is 001 to 0.2.

7. The method of claim 1 , wherein r D =r DH ; wherein r D is 5 to 25 mm; wherein R D is 20 to 100 mm; wherein r C is 20 to 100 cm.

8. The method of claim 1 , wherein deriving the polishing layer from the cake, comprises:

skiving the cake into a plurality of polishing layers.

9. The method of claim 1 , wherein the curable mixture is charged to the mold cavity at an essentially constant rate over the charging period, CP, with an average charging rate, CR avg , of 0.015 to 1 kg/sec.

10. The method of claim 1 , wherein the curable mixture is charged to the mold cavity at an essentially constant rate over the charging period, CP, with an average charging rate, CR avg , of 0.08 to 0.4 kg/see.

11. The method of claim 1 , wherein R D ≦(K*r C ), wherein K is 0.014 to 0.1.

12. The method of claim 1 , wherein R D ≦(K*r C ), wherein K is 0.04 to 0.086.

13. The method of claim 1 , wherein r D is 8 to 15 mm; wherein R D is 25 to 50 mm mm; wherein r C is 40 to 60 cm.

14. The method of claim 1 ,

wherein the transition phase is 0.02 to 30 seconds long; and,

wherein the remainder phase is ≧10 seconds long.

15. The method of claim 1 ,

wherein the location of the nozzle opening moves relative to the mold cavity's central axis, C axis , during the transition phase at an average speed of 10 to 70 mm/see; and,

wherein the location of the nozzle opening moves relative to the mold cavity's central axis, C axis , during the remainder phase at an average speed of 10 to 70 mm/sec.

16. The method of claim 1 ,

wherein during the remainder phase the location of the nozzle opening moves from a remainder phase starting point, SP RP , through a plurality of remainder phase transition points, TP RP ;

wherein a remainder phase path projects a series of connected lines onto the x-y plane during the remainder phase;

wherein the plurality of remainder phase transition points, TP RP , are all located within the doughnut region of the mold cavity; and,

wherein the series of connected lines approximates a circle or a two dimensional spiral with a varying distance from the mold cavity's central axis, C axis .

17. The method of claim 16 ,

wherein the transition phase is 0.2 to 5 seconds long;

wherein the remainder phase is 30 to <(CP-0.2) seconds long;

wherein the location of the nozzle opening moves relative to the mold cavity's central axis, C axis , during the transition phase at an average speed of 20 to 30 mm/sec; and,

wherein the location of the nozzle opening moves relative to the mold cavity's central axis, C axis , during the remainder phase at an average speed of 20 to 30 mm/sec.

18. The method of claim 16 , wherein the series of connected lines is a regular polygon; and, wherein the regular polygon has ≧5 sides and ≦20 sides.

19. The method of claim 17 , wherein the series of connected lines is a regular polygon; and, wherein the regular polygon has ≧5 sides and ≦20 sides.

20. The method of claim 17 , wherein the series of connected lines is a regular polygon; and, wherein the regular polygon has 8 to 15 sides.