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US 6,457,852 B1Granted
Apparatus and method for supplying chemicals
AssigneeFujitsu Limited
InventorsNaoki Hiraoka, Takeshi Hiraide
Life of this patent
Estimating the term…
Abstract
A chemical supplying apparatus includes first and second mixing tanks for mixing and supplying chemical slurries used in a semiconductor fabrication process. The slurries are alternately provided from the first and second mixing tanks such that the slurry is continuously available to a processing apparatus for maximum efficiency. While one of the tanks is supplying the slurry, the other tank is cleaned and then used to prepare a new batch of the slurry.
Claims22
A chemical supply apparatus for preparing a mixture by mixing a plurality of stock chemicals and supplying the mixture to at least one processing unit, the apparatus comprising:
- a plurality of mixing tanks for preparing the mixture by mixing predetermined amounts of the stock chemicals, each mixing tank having a capacity corresponding to an amount of the mixture required by the processing unit;
- a main circulating pipe commonly connected to the plurality of mixing tanks for supplying the mixture in the mixing tanks to the processing unit;
- a plurality of supply pipes connected to each of the mixing tanks, respectively, to supply the stock chemicals of the mixture to each one of the mixing tanks;
- a plurality of liquid level sensors for respectively measuring the amount of liquid disposed in each of the mixing tanks;
- a plurality of selector valves respectively connected between each of the mixing tanks, the supply pipes, and the main circulating pipe, for selectively connecting one of the mixing tanks to the main circulating pipe and to its respective supply pipes;
- a flushing system for flushing each mixing tank and its supply pipe;
- and
- control unit means for controlling the selector valves in response to the liquid levels in the mixing tanks detected by the liquid levels in the mixing tanks detected by the liquid level sensors, said control unit means including means operative to active selector valves for supplying stock chemicals to a mixing tank not connected to the main circulating pipe while the one mixing tank is supplying its mixture to the processing unit and, when the liquid level of the mixture in the one mixing tank reaches a first predetermined low level, the control unit means also containing means operative to switch supply of stock chemicals from said not connected mixing tank to the processing unit, and wherein the control unit means has means for controlling the flushing system to flush the one mixing tank and its supply pipe when the mixture in the one mixing tank drops below the predetermined low level while the not connected mixing tank is supplying its mixture to the processing unit.
5 more elements
A chemical supply apparatus for preparing a mixture by mixing a plurality of stock chemicals and supplying the mixture to at least one processing unit, the apparatus comprising:
- a first mixing tank and a second mixing tank for preparing a batch of the mixture by mixing predetermined amounts of the stock chemicals and water, each mixing tank having a capacity corresponding to an amount of the mixture required by a processing unit, each mixing tank;
- a main circulating pipe commonly connected to each of the first and second mixing tanks for supplying the mixture in the mixing tanks to the processing unit;
- a first supply pipe and a second supply pipe connected to the first and second mixing tanks, respectively, to supply the stock chemicals of the mixture to each of the mixing tanks;
- a liquid level sensor provided with each of the mixing tanks for respectively measuring the amount of liquid disposed in each of the mixing tanks;
- first and second selector valves respectively connected between each of the mixing tanks, the supply pipes, and the main circulating pipe, for selectively connecting one of the mixing tanks to the main circulating pipe and to its respective supply pipes;
- a flushing system for flushing each mixing tank and its supply pipe;
- and
- control unit means for controlling the selector valves in response to the liquid levels in the mixing tanks detected by the liquid level sensors, the control unit means including means to activate selector valves for connecting one of the mixing tanks to the main circulating pipe and the other mixing tank to its circulating pipe, said control unit means including further means effective when the liquid level of the mixture in the one tank reaches a first predetermined low level to begin to prepare a new batch of the mixture in the other mixing tank, and wherein the control unit means includes means for controlling the flushing system to flush the one mixing tank and its supply pipe when the mixture in the one mixing tank drops below the first predetermined low level while the other mixing tank is preparing the mixture.
5 more elements
Dependencies are inferred from the claim text.