Contaminant free high purity liquid dispensing system

Abstract

 © Apparatus is provided for transferring into a dispenser reservoir (21) free of contamination from a sealed bulk container (10), such as a bottle used in shipping high purity liquid, e.g. electronic chemicals. The dispenser (20) is provided with an adapter (22) to interlock on the bottle (10) and thereafter to perforate the sealed opening in the bottle and allow transfer of the liquid without exposure to ambient contamination. The dispenser (20) is provided with a check valve (26) which halts the flow of liquid from the reservoir before the liquid supply is depleted to prevent air from being pulled into the system. The dispenser reservoir (21) compartment is formed with a liquid accumulating bottom (21a) provided with the check valve at the lower end of the compartment.

Description

BACKGROUND OF THE INVENTION

[0001] Various liquids which are shipped in bulk containers are exposed to conditions which adversely affect the level of purity of these liquids. In many situations the maintenance of high purity is necessary for the practical acceptance of the liquid. For example, in semiconductor manufacturing processes it is essential that chemicals of high purity be used, otherwise the resulting product is likely to be unacceptable. The source of contamination for these high purity liquids may be encountered at various stages in the handling of such liquids. For example, contaminants may be introduced when the liquid in the bulk container, for which great care has been expended to avoid impurities, is withdrawn using dip tubes which may be exposed to contaminants through repeated use; or when contact is made with contaminated dispensing equipment that comes into contact with the opening of the container, or its liquid is being dispensed from the opening, of the shipping container; or when the container is recapped to preserve the balance of unused contents for later use. In these and other situations the contaminant comes from sources that are oftentimes difficult to trace or it may even come from contaminated air which displaces the liquid withdrawn from the container. In some instances, to avoid pulling air into the system, a quantity of liquid is allowed to remain in the bulk (shipping) container when the change to a fresh container is made. This precludes the possibility of introducing unwanted air into the system as well as impurities with the air which would contaminate the liquid. However, such residual amounts of liquid which is left in the container and discarded, in the aggregate, constitute a considerable economic waste.

[0002] In the past various means to minimize sources of contamination have been employed. U.S. Patent 3,941,270, for example, discloses a bulk liquid container with a seal which may be perforated by a hollow spike perforator when the liquid from the container is to be dispensed. In the arrangement of U.S. Patent 3,941,270 the top of the bulk container is inverted on the perforating device to remove the liquid impervious seal and allow the liquid to flow. In that arrangement considerable risk of contamination is present at the contact between the container opening, which is relatively loose fitting and which sometimes results in premature perforation of the seal.

[0003] It is apparent, accordingly, that a need exists for a system that prevents contamination of high purity liquids in a bulk container in the process of transferring, i.e. dispensing, the liquid from the container, in a more reliable and efficient manner while maintaining the necessary high level of purity of the liquid and precluding the entry of air into the liquid dispensing line.

SUMMARY OF THE INVENTION

[0004] The invention comprises a container devised for secure shipment and dispensing of a high purity liquid, a dispenser having a liquid reservoir for dispensing the liquid and a valving means to prevent entry of air into the line through which the liquid is withdrawn from the dispenser. The dispenser is closed against contamination and is provided with a float or other means to stop flow of the liquid when the liquid therein is near depletion. The dispenser is provided with a puncturing device to perforate the seal of a bulk (shipping) container from which the liquid is introduced into the dispenser. The dispenser and bulk container are provided with mating mechanical interlocking means, such as mating threads, so that as the container is positioned on the dispenser, perforation of the seal on the bulk container occurs when the container is inserted on the opening of the dispenser and then locked to prevent contamination. The system of the present invention, comprising the dispenser, the bulk container (which is penetrated to feed the liquid into the dispenser only when the two are interconnected and exposure from contamination into the liquid is precluded) and the air interlock means affords novel and highly practical advantages.

[0005] The dispenser of the invention comprises a container preferably with a slanted or interior concave bottom having a suitable capacity such as about 3 liters or more. At the lower part of the bottom a flow control means is used such as a float valve which leads to a feed tube attached outside the container. The feed tube leads to a pump which delivers high purity liquid, such as a photoresist to a coating or other dispensing equipment used for example in semi-conductor manufacturing. The float valve closes when the liquid level becomes low, thus shutting off flow and eliminating the possibility of air entering the feed tube.

[0006] The top of the dispensing container is removable and contains in its center a fitting which has a depressed center with drain holes that permit liquid material to flow into the container. In the middle of this fitting is a hollow perforating or puncturing device which is hollow and contains openings to permit liquid to flow into the container through the drain holes in the fitting.

[0007] The bulk shipping container or bottle of high purity liquid, such as photoresist, used in the system of the invention utilizes a cap with a round hole in the center which exposes a perforatable flexible plastic cap liner which seals the container. A second larger set of threads match threads on the interior of the center fitting and enable the bottle of photoresist to be rigidly held in place once it is seated. In feeding the dispenser from the bulk container, an outer protective cap is removed from the bulk container or bottle, exposing the bottle cap with the perforatable plastic cap liner. The shipping bottle is inverted and the puncturing device is pushed into the center hole of the cap and into the bottle. The flexible cap liner is pushed aside or perforated and the liquid flows into the dispenser reservoir. The float valve which controls flow from the reservoir then rises, permitting flow of the liquid into the feed tube of the pump.

[0008] Once the bottle is empty, it can be removed and replaced by a full bottle. The capacity of the dispenser reservoir permits continuous operation of the dispensing equipment, even if an empty bottle is not immediately replaced by a full bottle of the high purity liquid.

[0009] The dispenser may employ a sight glass or other gauge to signal the level of the high purity liquid in the dispenser reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] 

FIG. 1 is a diagramatic view of an inverted bulk container positioned over the high purity liquid dispenser equipped with a perforating device to puncture the container sealed opening.

FIG. 2 is a fragmentary view of the pouring end of a bulk container with closure cap and overcap shown in cross-section.

FIG. 3 is a fragmentary view in cross-section of the bulk container pouring end, from which the over cap has been removed, positioned above the feed entry to the dispenser with the perforating device positioned in the feed entry to the dispenser reservoir.

FIG. 4 is a fragmentary view similar to FIG. 3 showing the pouring end of the bulk container with container seal punctured and in locked position on the dispenser.

FIG. 5 is a cross-section of a float valve that may be employed with the invention to function in cutting off flow when the level in the reservoir is near depletion and before air can enter the piping system.

FIG. 6 illustrates an alternative embodiment of the invention wherein the reservoir comprises a slanted bottom.

FIG. 7 illustrates another embodiment wherein the reservoir comprises a cone-shaped bottom.

PREFERRED EMBODIMENT OF THE INVENTION

[0011] In accordance with the invention a system for dispensing high purity liquids is provided. As shown by reference to FIG. 1, the system comprises a dispenser unit shown generally at 20 which is adapted to receive a bulk container shown generally at 10 in which the high purity liquid is shipped. The system is devised to receive the mouth or nozzle 16 of the shipping container or bottle 10 while it is still in a sealed condition into a receiving adaptor 22 of the dispenser 20. After the bottle 10 is inserted and is in proper position with the bottle nozzle 16 into the adapter 22, the seal 34 on the bottle opening is perforated when the bottle opening is positioned on the puncture mechanism 48 and interlocked by rotating it as will be described hereafter in greater detail. This interlocking precludes contamination during the transfer from the bulk container to the dispenser 20.

[0012] The dispenser 20 comprises a container which may generally be cylindrical in cross-section having a reservoir 21 of suitable capacity, for example 3 liters or more. The reservoir 21 is preferably formed so that it has a domed bottom 21a to better utilize the liquid remaining in the reservoir as the liquid nears depletion. The reservoir may also be formed to have a slanted bottom as shown at 21b in FIG. 6.

[0013] At the lower part of the dome bottom 21a (FIG 1) is a float valve, shown in phantom at 26, which leads to a feed tube 28 attached outside the dispenser container 20. When the liquid to be dispensed is an electronic chemical, such as a liquid photoresist composition, which must necessarily be maintained in high purity, the feed tube 28 may lead to a pump (not shown) which delivers photoresist to the coating or other equipment. The float valve 26 shown in greater detail in FIG. 5 closes when the liquid level becomes low, thus shutting off flow and eliminating the possibility of air entering the feed tube 28.

[0014] The top of the dispensing container 20 is removable and contains in its center a fitting 22 which has a depressed center with drain holes 42 that permit liquid material to flow into the container reservoir 21. In the middle of this fitting 22 is a round pointed puncturing device 40 which will be described by reference to FIGS. 4 and 5. The puncturing device 40 is also perforated at 41 to permit liquid flow into the container through the interior of the puncturing device 40.

[0015] The bottles of high purity liquid used with this invention utilize a cap 17 with a round hole in the center 17a which exposes a perforatable plastic cap liner held on a first set of threads 18. A second larger set of threads 14 match threads on the interior of the center fitting and enable the bottle of photoresist to be rigidly held in place once it is seated on the dispenser.

[0016] In use, an outer protective over cap 11 is removed from the shipping container or bottle 10, exposing the bottle cap 17 with the plastic cap liner or seal 30. The bottle 10 is inverted and the puncturing device 40 penetrates the seal 30 which comprises an inner seal 34 and an outer seal member 32, the latter preferably is provided with a central perforation as described in greater detail in U.S. Patent 3,941,270. As the bottle 10 is lowered on the puncture mechanism penetrating the cap 17 and pushing aside the seal 30, it is rotated locking threads 14 and 24. The liquid flows into the container reservoir 21 from the opening thus provided. When sufficient liquid is present in the reservoir 21 of dispenser 20, the float valve 26 rises, permitting flow into the feed tube 28 to the pump (not shown).

[0017] Once the bottle is empty, it can be removed and replaced by a full bottle. The capacity of the dispenser reservoir permits continuous operation of the equipment even if an empty bottle is not immediately replced by a full bottle of photoresist.

[0018] The float valve shown in FIG. 5 is typical and comprises a body 50 containing therein a float 51 formed with precision mating surfaces to effect a tight seal between the surfaces 50a and 51a when the float is in the down position. As shown the float 51 is in the elevated position resting against the retainer rod 52 which keeps the float 51 in place. Liquid enters the annular space 53 from the top at 54 and/or from openings 55 in the sides of the body 5U. When the liquid is diminished in the reservoir to a level about mid-way of the vertical height of the float 51, the float sits on the mating body (base) surface 50a and shuts off flow to tubing 28 (FIG. 1). The function of the float valve, as will be apparent to one skilled in the art, and may be performed by other flow control means such as a level control operating a solenoid valve 63 (shown in FIG. 6).

[0019] As disclosed in U.S. Patent 3,941,270, the bottle or bulk container 10 is appropriately sealed to maintain high purity of the liquid during shipment. As described herein the flexible liquid impervious sealing member 30 comprises first and second adjacent flexible discs 32 and 34 respectively. The first disc 32 may be provided with a centrally located circular perforation as shown by reference to U.S. Patent 3,941,270 and the second disc is imperforate and covers the circular perforation in the first disc. The circular perforation in the first disc is provided so that the tip of the puncture mechanism 40 will engage the pertoration and carry the first disc 32 and adjacent second disc 34 away from the top wall of the screw closure cap 17 so that after the discs are removed, they will not interfere with flow ot liquid from the container through the perforate portion 17a of the top wall 17b.

[0020] A single flexible sealing disc may be used. However, a pair of discs is preferred. When more than one disc is used, the first disc 32 provides support for the second disc 34 and therefore may be less flexible than the second disc. The second disc 34 may be gas permeable so that if the liquid in the container produces gas upon exposure to heat or light, the gas will pass through. The sealing disc combination 30 may include additional elements. For example, when the second disc is a thin gas permeable disc it may be disposed between third and fourth discs which are provided for structural support of the second disc with the third and fourth discs provided with centrally located slits, the third disc being in contact with the first end of the cylindrical member and the fourth disc being disposed between the first and second discs. The thickness, properties and character, e.g. gas permeability, of the seal elements are selected to provide the necessary protection under ambient conditions.

[0021] Details of the sealing elements for the shipping container comprising the inner cap 17 and seal combination 30 of elements within the cap 17 are provided in U.S. Patent 3,941,270 which is incorporated herein by reference.

[0022] In operation, the sealing member 3U may be removed from the open end of the bulk container 10 by applying pressure upon the sealing member 30. When such pressure is applied by the perforator 40, the sealing member disengages or is perforated thus permitting communication through the perforate portion through the perforator 40 to the dispenser reservoir 21 from the bottle 10.

[0023] The pressure may be applied through the perforate portion by a hollow spike perforator 40 which is provided with openings 41 to permit entry of liquid from the hollow portion into the hollow spike 40 for carrying the liquid through the hollow spike to the dispenser reservoir 21. The hollow spike 40 is conveniently attached to a supporting surface 22 by suitable means. The supporting fixture 22 is secured on the reservoir cover 23.

[0024] As shown in FIG. 6 the solenoid operated level control 60 comprises a sensor 61 which is partially submerged and senses the liquid level 62. When the level falls below the predetermined level 62a, the level sensor 60 causes solenoid valve 63 to close until the liquid level is again raised, thus preventing air from entering piping 28.

[0025] FIG. 7 illustrates a cone shaped reservoir 65 provided with a valve 26a and discharge tube 28a which correspond in function to valve 26 and line 28 respectively described by reference to FIG. 1.

[0026] Although the invention has been described and illustrated in connection with preferred embodiments, it will be understood that modifications and variations may be made without departing from the essence and scope of the invention as defined in the appended claims.

Claims

1. A dispensing apparatus for transferring high purity liquids from a bulk container to the dispensing apparatus without exposing said liquid to ambient conditions comprising:

(a) a dispenser which includes a closed reservoir compartment for receiving and dispensing high purity liquid through a dispensing line;

(b) a valve means on said dispensing apparatus to automatically stop the flow of liquid from the dispenser reservoir when the liquid in the reservoir is substantially depleted and before air is pulled into the dispensing line from the air space in the reservoir; and

(c) a bulk container adapter on said dispensing apparatus to receive and to hold the opening of a sealed bulk container of said liquid when the container is in position on said adapter and including a perforating member to perforate the sealed opening of the bulk container, said sealed opening being constructed so as to mate with said adapter.

2. The system of claim 1 provided additionally with a bulk container and mating means on said bulk container and on said adapter to interlock the container to the dispensing apparatus on said adapter.

3. The system of claim 1 wherein the reservoir compartment is formed with a slanted bottom and the valve means are positioned at a lower end of said slanted bottom.

4. The system of claim 1 wherein the reservoir compartment is formed with a dome-shaped bottom.

5. The system of claim 1 wherein the reservoir compartment is formed with a cone-shaped bottom.

6. The system of claim 1 wherein the reservoir compartment is provided with a liquid depth gauge to indicate the level of liquid content in said compartment.

7. The system of claim 1 wherein the spike comprises a hollow member with perforations permitting a flow of liquid from the perforated container opening through the spike to the reservoir compartment.

Drawing