초록 ▼

The present invention provides an apparatus 20 for forming a striation-reduced chemical mechanical polishing pad 4. The polishing pad 4 comprises a first delivery line 66 for delivering a polymeric material 52 into a mixer 68 and a second delivery line 44 for delivering microspheres 48 into the mix

The present invention provides an apparatus 20 for forming a striation-reduced chemical mechanical polishing pad 4. The polishing pad 4 comprises a first delivery line 66 for delivering a polymeric material 52 into a mixer 68 and a second delivery line 44 for delivering microspheres 48 into the mixer 68 with the polymeric material 52. The second delivery line 44 is connected to a bulk density control unit 21. The bulk density control unit 21 comprises a storage hopper 22 for storing the microspheres 48. The storage hopper 22 further comprises a porous membrane 24 provided over a plenum 26. A fluidizing gas source 23 is connected to the plenum 26 through a gas inlet line 27. Gas 28 fed into the plenum 26 from the fluidizing gas source 23 permeates through the porous membrane 24 and reduces the initial bulk density of the microspheres 48 in the storage hopper 22.

대표청구항 ▼

What is claimed is: 1. An apparatus for forming a striation-reduced chemical mechanical polishing pad, comprising: a first delivery line for delivering a polymeric material into a mixer; a second delivery line for delivering microspheres having an initial bulk density into the mixer with the polyme

What is claimed is: 1. An apparatus for forming a striation-reduced chemical mechanical polishing pad, comprising: a first delivery line for delivering a polymeric material into a mixer; a second delivery line for delivering microspheres having an initial bulk density into the mixer with the polymeric material, the second delivery line being connected to a bulk density control unit, the bulk density control unit comprising: a storage hopper for storing the microspheres, wherein the storage hopper further comprises a porous membrane provided over a plenum and an agitator to facilitate fluidization of the microspheres in the storage hopper; a fluidizing gas source connected to the plenum through a gas inlet line; and a recirculation loop for recirculating the microspheres and controlling bulk density of the microspheres, wherein the recirculation loop has a mass flow sensor for measuring a continuous bulk density of the microspheres passing therethrough, and controlling the bulk density, wherein gas fed into the plenum from the fluidizing gas source permeates through the porous membrane and adjusts the initial bulk density of the microspheres in the storage hopper. 2. The apparatus of claim 1 wherein the bulk density unit further comprises a secondary fluidizing gas source for further reducing the bulk density of the microspheres. 3. The apparatus of claim 1, wherein the agitator is a helical agitator. 4. The apparatus of claim 3, wherein the clearance between the helical agitator and the porous membrane is 0.0127 to 0.0381 m.