| 摘要 |
The present invention is directed to an apparatus and method for flow regulation of planarization fluids to a semiconductor wafer planarization machine. In one embodiment, the regulating system includes a fluid storage tank with an acoustic fluid level sensor. The storage tank is connected to a fluid delivery line that delivers planarization fluid to the storage tank through a flow control valve and delivers a regulated flow of planarization fluid to a planarization machine through a flow sensor. A gas supply system is connected to the storage tank to provide system pressurization. Regulation of the fluid flow is achieved by a control system in which the flow sensor and the acoustic fluid level sensor comprise feedback elements in a closed feedback system to independently control the pressure in the storage tank and the fluid admitted by the control valve. In an alternate embodiment, the fluid level sensor is comprised of capacitive proximity sensors located outside the wall of the storage tank. In another embodiment, the fluid level sensor is replaced by a buoyant float that can seat in the upper or lower ends of the storage tank and a differential pressure sensor that senses differences in storage tank pressure when the float is seated in either of these locations to indicate full or empty tank conditions. In still another aspect, two or more regulators may be joined in a parallel flow arrangement in order to achieve precise point-of-use mixing of multi-component planarization fluids.
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