Continuous feed, chemical switching unit

A continuous feed, chemical system for supplying an uninterrupted flow of chemical fluid to a process tool comprising in operative combination:

• a) a plurality of removable bottles, each containing a quantity of chemical fluid and having a fluid outlet line, said plurality of bottles including a first chemical fluid bottle and a second, alternate standby chemical fluid bottle;
• b) a reservoir disposed downstream of said plurality of chemical fluid bottles for holding a predetermined amount of chemical fluid, said reservoir having an air outlet port, a fluid outlet port and a plurality of fluid inlet ports, each of said fluid inlet ports are communicatively coupled with respective ones of said chemical fluid bottle fluid outlet lines;
• c) conduit means for communicatively coupling said fluid outlet port of said reservoir to a chemical fluid receiving port of said process tool;
• d) pump means disposed along said conduit means for transferring chemical fluid from said reservoir to said process tool via said conduit means;
• e) vacuum means connected to said air outlet port of said reservoir and operative to generate a negative pressure within said reservoir sufficient to draw chemical fluid from an active chemical fluid bottle;
• f) a plurality of bottle selector valve means each of which are associated with individual ones of said chemical fluid bottle fluid outlet lines, each of said valve means having two operational modes including
• i) a first active mode for permitting fluid flow from an associated chemical fluid supply bottle to said reservoir, and
• ii) a second nonactive mode for preventing fluid flow from an associated chemical fluid supply bottle to said reservoir;
• g) sensor means for monitoring the fluid level within said reservoir, said sensor means comprises a float level sensor array including a first full-level sensor, a second fill-level sensor and a third empty-level sensor, wherein:
• i) activation of said full-level sensor disables said vacuum means;
• ii) activation of said fill-level sensor re-enables said vacuum means and signals an alarm condition to a control means to selectively operate said valve means for bottle switching operation from said first bottle to said second standby alternate bottle;
• iii) activation of said empty-level sensor disables all of said bottle selector valve means and said vacuum means, and provides an interlock signal to said process tool to stop continued processing;
• and
• h) an electronic control means communicatively coupled with each of said valve means and said sensor means for selectively enabling the mode operation of each of said valve means to switch the status of a bottle from which chemical fluid is actively being withdrawn to a nonactive status and the standby status of a full alternate bottle to active withdrawal of chemical fluid therefrom in response to signal information received from said sensor means.