Polishing composition storage container
View Patent ↗The invention provides devices and methods for removing and trapping large and/or dense abrasive particles from a polishing slurry. The polishing slurry is introduced into a container and allowed to stagnate, thereby causing large and/or dense particles to separate from the slurry under the influence of gravity. The container includes a cavity or plurality of cavities defined by an inner surface of the container into which the separated particles sink. To prevent the large and/or dense particles from becoming re-suspended into the slurry, the size and shape of the cavity is relatively deep and narrow with respect to the large and/or dense particles, thus providing a trapping effect. The cavities do not effectively trap the smaller particles.
1. A container for transporting and/or storing a polishing slurry having abrasive particles suspended therein, the container comprising:
an interior surface defining a volume for storing the slurry, the interior surface further defining a cavity for retaining abrasive particles settling from the slurry; and
an opening for receiving and/or emptying the slurry,
wherein the container defines a volumetric capacity and the cavity is sized to retain about 0.1 wt. % to about 5 wt. % of the total abrasive particles in the slurry when the container is filled to capacity, and
wherein the cavity has (a) a width from about 0.5 mm to about 10 mm,(b) a depth from about 0.5 mm to about 10 mm, or (c) a width from about 0.5 mm to about 10 mm and a depth from about 0.5 mm to about 10 mm.
2. The container of claim 1 , wherein the cavity is a plurality of cavities.
3. The container of claim 1 , wherein the plurality of cavities numbers about 5 or more cavities.
4. The container of claim 1 , wherein the plurality of cavities numbers about 20 or more cavities.
5. The container of claim 1 , wherein the container defines a volumetric capacity and the cavity is sized to retain between about 0.5 wt. % to about 5 wt. % of the total abrasive particles in the slurry when the container is filled to capacity.
6. The container of claim 1 , wherein the cavity has a width from about 0.5 mm to about 10 mm.
7. The container of claim 1 , wherein the cavity has a depth from about 0.5 mm to about 10 mm.
8. The container of claim 2 , wherein the plurality of cavities are shaped in the form of holes.
9. The container of claim 8 , wherein the shape of the holes is circular, square, triangular, rectangular, or combinations thereof.
10. The container of claim 1 , wherein the cavity is shaped in the form of a groove.
11. The container of claim 10 , wherein the cavity has a dimension that is about the same as or greater than the largest dimension of the container.
12. The container of claim 10 , wherein the groove is arranged as a spiral, a cross hatch, or combinations thereof.
13. The container of claim 2 , wherein the plurality of cavities are in the form of grooves.
14. The container of claim 13 , wherein the grooves are arranged as concentric circles, multiple spirals, straight lines, arcs, or combinations thereof.
15. The container of claim 2 , wherein the cavities are separated from each other by a distance of about 2 mm to a distance of about 20 mm.
16. The container of claim 2 , wherein the plurality of cavities are separated by a distance of about 2 mm or less.
17. The container of claim 1 , wherein the container is cylindrical, square, or rectangular in shape.
18. The container of claim 1 , wherein the container has a volumetric capacity of about 1 liter to about 2,000 liters.
19. The container of claim 1 , wherein the container is made of plastic.
20. A method of removing large and/or dense abrasive particles from a polishing slurry comprising abrasive particles suspended in a liquid carrier, the method comprising:
providing a container having an interior surface defining a volume for storing the slurry and a cavity for retaining abrasive particles settling from the slurry;
introducing the slurry into the container;
allowing abrasive particles in the slurry to settle by gravimetric separation such that a portion of the abrasive particles is disposed in the cavity;
removing the slurry from the container while retaining the portion of the abrasive particles in the cavity, wherein the retained abrasive particles are about 0.5 wt. % to about 5 wt. % of the total wt. % of abrasive particles in the slurry when the container is filled to capacity.
21. The method of claim 20 , wherein the interior surface defines a plurality of cavities.
22. The method of claim 20 , wherein the retained abrasive particles are about 0.5 wt. % to about 5 wt. % of the total wt. % of abrasive particles in the slurry when the container is filled to capacity.
23. The method of claim 20 , further comprising the step of stirring the slurry.
24. The method of claim 20 , further comprising the step of filtering the slurry.
25. A polishing apparatus comprising the following:
a container including an opening for receiving a slurry having abrasive particles suspended therein, the container further including an interior surface defining a volume for storing the slurry and a cavity, wherein the cavity is sized to retain about 0.1 wt. % to about 5 wt. % of the total abrasive particles in the slurry when the container is filled to capacity,
a polishing tool including a platen, a polishing pad, and a carrier for holding a wafer to be polished; and
a means for transporting the slurry from the container to the polishing tool.
26. The polishing apparatus of claim 25 , wherein the interior surface defines a plurality of cavities.
27. The polishing apparatus of claim 25 , wherein the apparatus further comprises a stirrer for stirring or agitating the slurry in the container.
28. The method of claim 20 , wherein the cavity has (a) a width from about 0.5 mm to about 10 mm, (b) a depth from about 0.5 mm to about 10 mm, or (c) a width from about 0.5 mm to about 10 mm and a depth from about 0.5 mm to about 10 mm.
29. The apparatus of claim 25 , wherein the cavity has (a) a width from about 0.5 mm to about 10 mm, (b) a depth from about 0.5 mm to about 10 mm, or (c) a width from about 0.5 mm to about 10 mm and a depth from about 0.5 mm to about 10 mm.