Slurry distribution system that continuously circulates slurry through a distribution loop

A slurry distribution system for distributing slurry to a plurality of polishing machines for polishing semiconductor wafers, the slurry distribution system comprising:

• a storage tank for storing the slurry;
• a mixing device for mixing the slurry in the storage tank, wherein the mixing device includes a motor, a shaft and a propeller, the motor and propeller are coupled to opposite ends of the shaft, the motor includes an external housing with a nitrogen purged cavity, the motor is outside the storage tank, the shaft extends through an opening in the housing and diagonally into the storage tank, and the propeller is near a bottom surface of the storage tank;
• a distribution loop with an inlet and outlet in fluid communication with the storage tank, wherein the distribution loop excludes the polishing machines;
• a plurality of valves in fluid communication with the distribution loop, wherein each of the valves are proximate to a respective point of use at a respective one of the polishing machines, each of the valves when opened dispenses the slurry to a respective one of the polishing machines, and each of the valves when closed prevents dispensing the slurry to a respective one of the polishing machines;
• and
• a pump for circulating the slurry from the storage tank to the inlet, from the inlet through the distribution loop to the outlet, and through the outlet to the storage tank regardless of whether the valves are opened or closed.

A slurry distribution system for distributing slurry to a polishing machine, the slurry distribution system comprising:

• a storage tank for storing the slurry, wherein the storage tank includes a bottom surface with a conical shape that slopes towards a centrally located position, and the storage tank includes vertical sidewalls adjacent to the sloped portion of the bottom surface;
• a mixing device for mixing the slurry in the storage tank, wherein the mixing device includes a motor, a shaft and a propeller, the motor and propeller are coupled to opposite ends of the shaft, the motor is outside the storage tank, the shaft extends diagonally into the storage tank, the propeller is in the storage tank, and the propeller faces and is coplanar with a sloped portion of the bottom surface, and wherein the propeller extends beneath the vertical sidewalls;
• a distribution loop with an inlet and outlet in fluid communication with the storage tank;
• a valve in fluid communication with the distribution loop for dispensing the slurry to the polishing machine;
• and
• a pump for circulating the slurry through the distribution loop regardless of whether the slurry is dispensed to the polishing machine.

A slurry distribution system for distributing slurry to a polishing machine, the slurry distribution system comprising:

• a storage tank for storing the slurry;
• a mixing device for mixing the slurry in the storage tank, wherein the mixing device includes a motor, a shaft and a propeller, the motor and propeller are coupled to opposite ends of the shaft, the motor includes an external housing with a purged cavity, the motor is outside the storage tank, the shaft extends through an opening in the housing and into the storage tank, and the propeller is in the storage tank;
• a distribution loop with an inlet and outlet in fluid communication with the storage tank;
• a valve in fluid communication with the distribution loop for dispensing the slurry to the polishing machine;
• and
• a pump for circulating the slurry through the distribution loop regardless of whether the slurry is dispensed to the polishing machine.

A slurry distribution system for distributing slurry to a polishing machine, the slurry distribution system comprising:

• a first storage tank for storing a first slurry adapted for polishing a first material;
• a second storage tank for storing a second slurry adapted for polishing a second material that is different than the first material;
• a distribution loop with an inlet and outlet;
• a first inlet valve for providing fluid communication between the inlet and the first storage tank;
• a second inlet valve for providing fluid communication between the inlet and the second storage tank;
• a first outlet valve for providing fluid communication between the outlet and the first storage tank;
• a second outlet valve for providing fluid communication between the outlet and the second storage tank;
• a dispense valve for dispensing slurry in the distribution loop to the polishing machine;
• and
• a distribution pump for circulating slurry in the distribution loop from the inlet to the outlet regardless of whether slurry in the distribution loop is dispensed to the polishing machine.