Transparent microporous materials for CMP

1. A chemical-mechanical polishing pad substrate comprising a porous material having an average pore size of about 0.01 microns to about 1 micron, wherein the polishing pad substrate has a light transmittance of about 10% or more at at least one wavelength of about 200 nm to about 35,000 nm.

2. The polishing pad substrate of claim 1 , wherein the polishing pad substrate has a light transmittance of about 30% or more at at least one wavelength of about 200 nm to about 35,000 nm.

3. The polishing pad substrate of claim 1 , wherein the average pore size is about 0.1 microns to about 0.7 microns.

4. The polishing pad substrate of claim 1 , wherein the porous material has a density of about 0.5 g/cm 3 or greater.

5. The polishing pad substrate of claim 4 , wherein the porous material has a density of about 0.7 g/cm 3 or greater.

6. The polishing pad substrate of claim 1 , wherein the porous material has a void volume of about 90% or less.

7. The polishing pad substrate of claim 6 , wherein the porous material has a void volume of about 25% or less.

8. The polishing pad substrate of claim 1 , wherein the porous material comprises a polymer resin selected from the group consisting of thermoplastic elastomers, thermoplastic polyurethanes, thermoplastic polyolefins, polycarbonates, polyvinylalcohols, nylons, elastomeric rubbers, elastomeric polyethylenes, polytetrafluoroethylene, polyethyleneteraphthalate, polyimides, polyaramides, polyarylenes, polystyrenes, polymethylmethacrylates, copolymers thereof, and mixtures thereof.

9. The polishing pad substrate of claim 8 , wherein the polymer resin is a thermoplastic polyurethane.

10. The polishing pad substrate of claim 1 , wherein the porous material comprises a three-dimensional metal oxide network.

11. The polishing pad substrate of claim 1 , wherein the substrate is a polishing pad.

12. The polishing pad substrate of claim 1 , wherein the substrate is a polishing pad window.

13. A chemical-mechanical polishing apparatus comprising:

(a) a platen that rotates,

(b) a polishing pad comprising the polishing pad substrate of claim 1 , and

(c) a carrier that holds a workpiece to be polished by contacting the rotating polishing pad.

14. The chemical-mechanical polishing apparatus of claim 13 , further comprising an in situ polishing endpoint detection system.

15. A method of polishing a workpiece comprising

(i) providing a polishing pad comprising the polishing pad substrate of claim 1 ,

(ii) contacting a workpiece with the polishing pad, and

(iii) moving the polishing pad relative to the workpiece to abrade the workpiece and thereby polish the workpiece.