1. A polishing pad comprising:
a polishing body comprising a thermoplastic foam substrate having a surface comprised of concave cells, wherein said thermoplastic foam substrate comprises a blend of cross-linked ethylene vinyl acetate copolymer and polyethylene, said thermoplastic foam substrate having a hardness ranging from about 24 Shore A to about 100 Shore A.
2. The polishing pad as recited in claim 1, wherein an interior of said thermoplastic foam substrate comprises a closed-cell foam.
3. The polishing pad as recited in claim 1, wherein said blend has an ethylene vinyl acetate copolymer:polyethylene ratio ranging from about 0.6:9.4 to about 9:1.
4. The polishing pad as recited in claim 1, wherein said blend has an ethylene vinyl acetate copolymer:polyethylene ratio ranging from about 8:1 to about 10:1.
5. The polishing pad as recited in claim 1, wherein said blend has an ethylene vinyl acetate copolymer:polyethylene ratio ranging from about 4:6 to about 6:4.
6. The polishing pad as recited in claim 1, wherein said blend has an ethylene vinyl acetate copolymer:polyethylene ratio of less than about 5:5.
7. The polishing pad as recited in claim 1, wherein said thermoplastic foam substrate has a hardness ranging from about 24 Shore A to about 34 Shore A.
8. The polishing pad as recited in claim 1, wherein said thermoplastic foam substrate has a hardness ranging from about 34 Shore A to about 55 Shore A.
9. The polishing pad as recited in claim 1, wherein said thermoplastic foam substrate has a hardness ranging from about 55 Shore A to about 65 Shore A.
10. The polishing pad as recited in claim 1, wherein said concave cells have an average size ranging from about 1 microns to about 25 microns.
11. The polishing pad as recited in claim 1, wherein said polyethylene is a low-density polyethylene.
12. The polishing pad as recited in claim 8, wherein said polyethylene is a medium-density polyethylene.
13. The polishing pad as recited in claim 8, wherein said ethylene vinyl acetate copolymer comprises from about 15 to about 20 wt % acetate.
14. A method for preparing a polishing pad comprising:
providing a polishing body comprising a thermoplastic foam substrate, where said thermoplastic foam substrate comprises a blend of cross-linked ethylene vinyl acetate copolymer and polyethylene, said thermoplastic foam substrate having a hardness ranging from about 24 Shore A to about 100 Shore A; and
exposing cells within said thermoplastic foam substrate to form a surface comprising concave cells.
15. The method as recited in claim 14, wherein said blend has an ethylene vinyl acetate copolymer:polyethylene ratio ranging from about 0.6:9.4 to about 9:1.
16. A polishing apparatus comprising:
a mechanically driven carrier head;
a polishing platen, said carrier head being positionable against said polishing platen to impart a polishing force against said polishing platen; and
a polishing pad attached to said polishing platen, said polishing pad including:
a polishing body comprising a thermoplastic foam substrate having a surface comprised of concave cells, wherein said thermoplastic foam substrate comprises a blend of cross-linked ethylene vinyl acetate copolymer and polyethylene, said thermoplastic foam substrate having a hardness ranging from about 24 Shore A to about 100 Shore A.
17. The polishing apparatus as recited in claim 16, wherein said polishing pad is capable of successively polishing a metal layer and a barrier layer on a semiconductor substrate at a ratio of removal rates of said barrier layer to said metal layer ranging from about 1:1 to about 5:1.
18. The polishing apparatus as recited in claim 17, wherein said barrier layer is selected from the group consisting of: tantalum, titanium, tantalum nitride and titanium nitride, and said metal layer comprises copper or tungsten.
19. A method for polishing a semiconductor wafer comprising:
providing a semiconductor substrate having a barrier layer over said semiconductor substrate and a metal layer over said barrier layer;
polishing said metal layer using a polishing pad,
wherein said polishing pad includes a polishing body comprising a thermoplastic foam substrate having a surface comprised of concave cells, wherein said thermoplastic foam substrate comprises a blend of cross-linked ethylene vinyl acetate copolymer and polyethylene copolymer, said thermoplastic foam substrate having a hardness ranging from about 24 Shore A to about 100 Shore A; and
polishing said barrier layer using said polishing pad.
20. The method as recited in claim 19, wherein said polishing pad in cooperation with said first and second slurry is capable of polishing said metal layer and said barrier layer at a ratio of removal rates of said barrier layer to said metal layer ranging from about 1:1 to about 5:1.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A development device comprising:
a developer storage chamber configured to store a developer;
a developer carrying member configured to carry the developer to develop an electrostatic latent image;
a light transmission member for transmitting detection light for detecting a remaining amount of a developer in the developer storage chamber;
a shaft member that is provided to the developer storage chamber and configured to rotate;
a conveyance unit that is provided to the shaft member and configured to convey the developer; and
a cleaning unit that is attached to the shaft member and configured to rub and clean the light transmission member at a position higher than a rotation center of the shaft member,
wherein the shaft member includes an opening at a position on an upstream side of the conveyance unit and on a downstream side of the cleaning unit in a rotational direction of the shaft member.
2. The development device according to claim 1, wherein the opening and the cleaning unit are provided on a same plane perpendicular to an axis of the shaft member.
3. The development device according to claim 1, wherein the opening is a through hole.
4. The development device according to claim 1, wherein the opening is a slit extended in a direction intersecting with the axis of the shaft member.
5. The development device according to claim 1, wherein the conveyance unit is a flexible sheet member.
6. The development device according to claim 1, wherein the cleaning unit is a flexible sheet member.
7. A process cartridge including an image bearing member configured to carry an electrostatic latent image and the development device according to claim 1, and detachably mounted on an image forming apparatus main body.
8. An image forming apparatus for forming an image on a recording medium, the image forming apparatus comprising:
an image bearing member configured to carry an electrostatic latent image;
the development device according to claim 1;
a light emitting element configured to emit the detection light;
a light receiving element configured to receive the detection light passed through the developer storage chamber; and
a detection unit configured to detect a remaining amount of a developer in the developer storage chamber based on an output of the light receiving element.
9. A development device comprising:
a developer storage chamber configured to store a developer;
a developer carrying member configured to carry the developer;
a light transmission member for transmitting detection light for detecting a remaining amount of a developer in the developer storage chamber;
a shaft member that is provided to the developer storage chamber and configured to rotate;
a conveyance unit that is provided to the shaft member and configured to convey the developer; and
a cleaning unit that is provided to the shaft member and configured to rub and clean the light transmission member,
wherein the shaft member includes an opening.
10. The development device according to claim 9, wherein the opening is provided at a position on an upstream side of the conveyance unit and on a downstream side of the cleaning unit in a rotational direction of the shaft member.