Fixed volume valve system

Abstract

Embodiments of the present invention provide valves that provide for uniform holdup volume. An embodiment of the present invention provides a valve comprising a valve body (e.g., one or more pieces) that defines a valve chamber having a valve seat, an inlet flow passage, an outlet flow passage and a diaphragm control flow passage intersecting the valve seat. The valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage. The valve further comprises a diaphragm movable towards and away from the valve seat. According to one embodiment of the present invention, the valve seat can have a semi-hemispherical shape to which the diaphragm conforms when a minimum vacuum is applied to the diaphragm control flow passage.

Description

RELATED APPLICATIONS [0001] The present application claims under 35 U.S.C. 119(e) priority to and the benefit of U.S. Provisional Application No. 60 / 742,147, entitled “VALVE PLATE SYSTEM AND METHOD” by Iraj Gashgaee et al., filed Dec. 2, 2005, [Atty. Dkt. No. ENTG1770] which is hereby fully incorporated by reference herein.TECHNICAL FIELD OF THE INVENTION [0002] This invention relates generally fluid valves. More particularly, embodiments of the present invention relate to valves for multi-stage pumps. Even more particularly, embodiments of the present invention relate to a valve plate that reduces hold up volume. BACKGROUND OF THE INVENTION [0003] There are many applications for which precise control over the amount and / or rate at which a fluid is dispensed by a pumping apparatus is necessary. In semiconductor processing, for example, it is important to control the amount and rate at which photochemicals, such as photoresist chemicals, are applied to a semiconductor wafer. The coat...

AI Technical Summary

Benefits of technology

[0006] Embodiments of the present invention provide valve systems and methods that substantially eliminate or reduce the disadvantages of previously developed valve systems and methods. More particularly, one embodiment of the present invention provides a valve comprising a valve body (e.g., one or more pieces) that defines a valve chamber having a valve seat, an inlet flow passage, an outlet flow passage and a diaphragm control flow passage intersecting the valve seat. The valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage. The valve further comprises a diaphragm movable towards and away from the valve seat. According to one embodiment of the present invention, the valve seat can have a semi-hemispherical shape to which the diaphragm conforms when a minimum vacuum is applied to the diaphragm control flow passage. It should be noted that the “semi-hemispherical” shape, for purposes of this application, can include a full hemisphere.

[0009] Embodiments of the present invention provide an advantage by eliminating or reducing the variability of hold up volume caused by outside influences. For example, embodiments of the present invention provide an advantage by reducing the effects of vacuum pressure on the displacement volume of a valve.

[0010] Embodiments of the present invention provide yet another advantage by reducing the hold up volume of a valve.

[0011] Embodiments of the present invention provide yet another advantage by increasing diaphragm life through reduced stress on the diaphragm.

Problems solved by technology

Some valve designs, however, exhibit characteristics that reduce repeatability.

The house pressure / vacuum used to open the valves is often not well controlled relative to the precision required in semiconductor manufacturing.

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