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Continuous feed, chemical switching unit
| Details |
Inventors: Fulton, Steven; Orthman, Lyle T.; Snodgrass, Eric R.;
Assignee: National Semiconductor Corporation (Santa Clara, CA)
Primary Examiner: Kashnikow; Andres
Assistant Examiner: DeRosa; Kenneth R.
Attorney, Agent or Firm: Dulin; Jacques M.
Continuous feed, chemical switching unit for supplying an uninterrupted flow of chemical fluid to a processing system including a control unit and a reservoir for containing a predetermined volume of chemical fluid wherein the reservoir is in hydraulic communication with a processing system. A plurality of float level sensors are provided within the reservoir for locating the fluid level in the reservoir wherein at least one level sensor provides an interlock to the processing system when energized to halt the processing system operation, and the other level sensors communicate reservoir level information to the control unit. The switching unit also includes a plurality of replaceable chemical fluid bottles for storing the fluid, e.g. a first active bottle and a second standby bottle, wherein the bottles are in independent hydraulic communication with the reservoir. Each fluid bottle has associated therewith an inert-gas actuated isolation valve for isolating the bottle from the reservoir. A vacuum source is in hydraulic communication with and for drawing a vacuum on the reservoir to cause fluid flow from an active bottle including an inert-gas actuated isolation valve associated therewith for isolating the vacuum source from the reservoir. The control unit is responsive to electrical signals from the level sensors, to an input power signal, and to a plurality of user commands, and is operative to generate signals to actuate the vacuum source isolation valve and the bottle isolation valves to switch the source of chemical fluid flow from one bottle to another as the first bottle becomes empty. Finally, an explosion-proof enclosure for housing the switching unit components wherein the enclosure is fitted with an exhaust device to vent explosive gases from the enclosure and is also equipped with a fire extinguishing device. |
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DETAILED DESCRIPTION OF THE BEST MODE A continuous feed chemical delivery system 220 is schematically depicted in FIG.
2.
The system 220 includes a switching unit 200, contained within a cabinet 201, wherein the unit 200 is in fluid communication with a typical prior art processing system 104.
The pumping system 106 delivers a chemical fluid (not shown) from the unit 200 to the photoresist processing system 104.
The pumping system 106 draws the fluid from the unit 200 via a suction pipe 108, and discharges the fluid to the processing system 104 via a discharge pipe 109.
A preferred embodiment of the switching unit 200 is used for servicing and supporting an IC wafer fabrication process.
More particularly, the unit 200 is used to store photo-resist material and support a photo-resist spin-coating processing system that is used for IC wafer fabrication.
However, it is understood that implementation of the unit 200 is not limited to supporting only this particular process and the switching unit may be used for supporting a variety of other processes including but not limited to use in combination with an acid developer, an acid processor, or use in a variety of bulk refill process operations.
Similarly, the switching unit may be used to control the continuous feed of a wide variety of fluids or chemicals.
The switching unit 200 is also communicatively coupled with the processing system 104 via a process interlock signal line 216.
When a system anomaly occurs such as, for example, where both chemical supply bottles are empty or the system malfunctions, the anomaly condition is communicated to the processing system 104 via signal line 216.
The switching unit 200 has several other input and output interfaces.
The unit 200 is communicatively coupled with a time set device ("Timer") 205, a reset device ("Reset") 207, a power supply device ("Power Supply") 209, a vacuum source 211, an alarm 213, and a plurality of inert gas storage containers 215, 217.
The time set device 205 provides a variable time base adjustment to accommodate a variety of fluid viscosities that are handled by the switching unit 200
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Control Computers 
