Chemical mechanical polishing retaining ring

Abstract

A chemical mechanical head includes a retaining ring to maintain a substrate beneath the mounting surface during polishing. The retaining ring has a lower portion with a bottom surface for contacting a polishing pad during polishing and made of a first material, such as plastic, and an upper portion made of a second, different material, such as metal.

What is claimed is: 
     
       1. A carrier head for a chemical mechanical polishing apparatus, comprising:
 a substrate backing member; 
 a first chamber to provide a first downward pressure on the substrate backing member; 
 a retaining ring assembly to maintain a substrate beneath the substrate backing member during polishing, the retaining ring assembly vertically movable relative to the substrate backing member, the retaining ring assembly including a lower portion retaining ring having a bottom surface for contacting a polishing pad during polishing and made of a first material, and an upper portion a backing ring made of a second, different material; and 
 a second chamber for containing a pressurized gas to provide a second independently controllable downward pressure on the retaining ring assembly that depends on gas pressure in the second chamber, wherein the second chamber is pressurizable independently of the first chamber and inflation of the second chamber urges the retaining ring downwardly. 
 
     
     
       2. The carrier head of  claim 1 , wherein the lower portion retaining ring is thicker than a the substrate to be polished. 
     
     
       3. The carrier head of  claim 1 , wherein the upper and lower portions retaining ring and backing ring are substantially annular in shape. 
     
     
       4. The carrier head of  claim 1 , wherein the first material is a plastic. 
     
     
       5. The carrier head of claim  1  4, wherein the first material is Delrin® plastic. 
     
     
       6. The carrier head of  claim 1 , wherein the second material is a metal. 
     
     
       7. The carrier head of  claim 6 , wherein the second material is aluminum. 
     
     
       8. The carrier head of  claim 1 , wherein the lower portion retaining ring is secured to the upper portion backing ring by screws. 
     
     
       9. The carrier head of  claim 8 , wherein the lower portion is secured to the upper portion by a key and key slot arrangement. 
     
     
       10. The carrier head of  claim 1 , wherein the upper portion backing ring is thicker than the lower portion retaining ring. 
     
     
       11. The carrier head of  claim 1 , further comprising a housing, and wherein the substrate backing member is movable relative to the housing. 
     
     
       12. The carrier head of  claim 11 , wherein the retaining ring assembly is movable relative to the housing. 
     
     
       13. A chemical mechanical polishing system, comprising:
 a rotatable polishing pad; 
 a slurry supply to dispense a slurry onto the polishing pad; and 
 a carrier head having a substrate backing member with a mounting surface, a first chamber to provide a first downward pressure on the substrate backing member, a retaining ring assembly to maintain a substrate beneath the mounting surface during polishing, the retaining ring assembly vertically movable relative to the substrate backing member, the retaining ring assembly including a lower portion retaining ring having a bottom surface for contacting a polishing pad during polishing and made of a first material, and an upper portion backing ring made of a second, different material, and a second chamber for containing a pressurized gas to provide a second independently controllable downward pressure on the retaining ring assembly that depends on gas pressure in the second chamber, wherein the second chamber is pressurizable independently of the first chamber and inflation of the second chamber urges the retaining ring downwardly. 
 
     
     
       14. The carrier head of claim 1, wherein the retaining ring has a top surface and through-holes formed from the top surface to the bottom surface. 
     
     
       15. The carrier head of claim 14, wherein the backing ring has a bottom surface with holes formed therein. 
     
     
       16. The carrier head of claim 1, wherein the backing ring includes an outwardly extending flange. 
     
     
       17. The carrier head of claim 1, wherein the backing ring includes an inwardly extending flange. 
     
     
       18. The system of claim 13, wherein the first material is a plastic. 
     
     
       19. The system of claim 18, wherein the first material is Delrin® plastic. 
     
     
       20. The system of claim 13, wherein the second material is a metal. 
     
     
       21. The system of claim 20, wherein the second material is aluminum. 
     
     
       22. The system head of claim 13, wherein the retaining ring is secured to the backing ring by screws. 
     
     
       23. The carrier head of claim 1, wherein the second chamber is in an inflatable bladder. 
     
     
       24. The system of claim 13, wherein the second chamber is in an inflatable bladder. 
     
     
       25. The carrier head of claim 1, further comprising a support plate and a gas supply passage through the support plate to supply the pressurized gas to the second chamber. 
     
     
       26. The system of claim 13, wherein the carrier head has a support plate and a gas supply passage through the support plate to supply the pressurized gas to the second chamber.