Chemical mix and delivery systems and methods thereof

Abstract

The present invention relates to chemical delivery systems and methods for delivery of liquid chemicals. In one embodiment, the present invention relates to systems having multi-reservoir load cell assemblies for delivering chemicals used in the semiconductor industry. In one embodiment, the present invention provides a multi-reservoir load cell assembly, including a controller, a buffer reservoir, a main reservoir, one or more load cells, coupled to the assembly and to the controller, operable to weigh the liquid in the reservoir(s), a plurality of supply lines, each supply line having a valve and connecting one of the supply containers to the main reservoir, and a gas and vacuum sources for withdrawing the liquid from the assembly when demanded by the controller and for refilling the assembly from the supply containers.

What is claimed:  
     
         1 . A method of liquid chemical delivery at low flow rates in a system comprising a multi-reservoir load cell assembly, including a main reservoir, a buffer reservoir, each reservoir having at least one load cell and a mixer, and a logic device, comprising: 
 isolating the main reservoir from the buffer reservoir;    reducing pressure in the main reservoir;    adding liquid chemical components sequentially into the main reservoir;    weighing each liquid chemical component by the multi-reservoir load cell assembly;    mixing the chemical components into a mixture;    supplying the main reservoir with an inert gas;    transporting mixture from the main reservoir to the buffer reservoir; and    transporting the mixture from the buffer reservoir through a pinch valve.