Systems and methods for transferring and delivering a liquid chemical from a source to an end use station

Abstract

Provided is a system for transferring and delivering a liquid chemical from a source to an end use station. The system includes: (a) a pressure vessel connected to a liquid chemical source by a delivery conduit, the pressure vessel having an internal surface; (b) a non-mechanical means of transferring the liquid chemical from the source through the delivery conduit to the pressure vessel; (c) a flexible liquid metering device disposed within the pressure vessel, the metering device having an interior and an interior surface and an exterior and an exterior surface; (d) a space adapted to receive the liquid chemical, the space being defined by at least a portion of the metering device external surface and at least a portion of the pressure vessel interior surface, or by at least a portion of the metering device internal surface; and (e) a pressurized gas conduit connected to a pressurized gas source for delivering the pressurized gas into the pressure vessel so as to contact the other of the interior or exterior surface of the metering device that defines the space, whereby the liquid chemical is forced out of the pressure vessel by the metering device to an end use station. Also provided is a method of transferring and delivering a liquid chemical from a source to an end use station. The invention has particular applicability to the semiconductor manufacturing industry for the distribution of ultrapure liquid chemicals to end use stations.

Description

[0001] 1. Field of the Invention[0002] This invention relates to systems for transferring and delivering liquid chemicals from a source to an end use station. The invention also relates to methods for transferring and delivering liquid chemicals from a source to an end use station. The invention has particular applicability to the semiconductor manufacturing industry for the distribution of ultrapure liquid chemicals to one or more end use stations.[0003] 2. Description of the Related Art[0004] In many manufacturing processes, various chemicals are required to be distributed from a bulk source to the point-of-use, i.e., end use station, without contamination or deterioration of the chemical quality. For example, in semiconductor wafer and computer chip manufacturing processes, ultrapure chemicals are needed for processes such as cleaning, etching, and surface treatment. These chemicals may include, for example, caustic, acids, and organic liquids, such as ammonium hydroxide, sodium ...

AI Technical Summary

Benefits of technology

[0014] Through the present invention, problems associated with chemical delivery in the related art have been overcome. For example, the invention makes use of a non-mechanical means of transferring the liquid chemical from the chemical source through the system. As a result, problems associated with pumps such as contamination of the chemical and downtime due to maintenance can be avoided. Also, the delivery system cost is reduced by eliminating the pump and other related components. Additionally, use of a flexible liquid metering device installed inside a pressure vessel isolates a high pressure gas from the chemicals, gas dissolution in the chemical and the resulted gas bubble problems are effectively eliminated. Further, contaminants in the high pressure gas which fills the metering device will not be transferred into the chemical and the extremely toxic chemical will not be transferred into the gas to be exhausted as a serious environmental issue. Unlike the vacuum / pressure system, the contamination by the ambient air leaking into the system is avoided because the disclosed delivery system is always with the pressure higher or equal to the ambient pressure.

Problems solved by technology

However, this "vacuum-pressure" method has several drawbacks.

First, the chemical can be contaminated by the leakage of ambient air into the system because of the negative pressure inside the system.

Another drawback is that the vacuum pump used to create the vacuum has high down-time because of the corrosion of the pump components by chemical vapor and droplets passing through the pump.

Yet another drawback is that the exhaust of the inert gas with the chemical vapor and droplets from the vacuuming procedure produces an environmental concern.

The bubbles may result in a serious quality problem in the wafer and electronic chips being manufactured.

However, the chemical quantity in the container is difficult to be monitored, and therefore, it is difficult to continuously deliver the chemical.

Another drawback of this method is that the distribution system with this method cannot be controlled automatically.

Further, the collapsible container can be easily broken especially at the fixing points under high pressure because of the disjoining force of the high pressure gas.

This lift force, however, is still not high enough for many applications, especially for the practice of viscous chemicals and long distance delivery.

Another drawback is the contamination of the impurities shed from the components of the distribution system due to the flow pulsation produced by the pump.

Some of the above mentioned drawbacks with the vacuum / pressure and the pump delivery methods still exist.

First, the gas directly contacts with the chemical will dissolve in the chemical and form bubbles that can result in serious problems on the wafer or microchip surface.

Second, the impurity shedding from the filters and other components by the pulsation upon pump startup will contaminate the ultrapure chemicals.

However, periodic pump maintenance can terminate chemical delivery.

In addition, the pump, conduits, filters and other components associated with the pump increases the cost of the system.

Further, contaminants in the high pressure gas which fills the metering device will not be transferred into the chemical and the extremely toxic chemical will not be transferred into the gas to be exhausted as a serious environmental issue.

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