Patent ID: 12226715

DETAILED DESCRIPTION OF THE DISCLOSURE

Embodiments of the degasser of the invention will be described in greater detail below with reference toFIGS.2to5. The degasser operates to remove any of the inert gas that has been entrapped or dissolved in a processing fluid. As a result of the operation of the degasser, the processing fluid delivered by a conduit to a tool has little or no entrapped or dissolved gas in the processing fluid. The liquid flow meter is presented with a substantially gas-free liquid and therefore can accurately measure the amount of liquid passing along the conduit on its way to the tool.

An attempt was made to give elements that are the same or similar inFIGS.2-5the same or similar reference numerals.

One embodiment of a portion of the degasser of the invention is shown inFIG.2.FIG.2shows one example of a vacuum chamber62and the one or more than one separator housed within the vacuum chamber62. The vacuum chamber62as shown is defined by a vertical cylinder wall63, a top wall24, and an oppositely located bottom wall25. First and second fluid inlets22A,22B (collectively or singly, the inlet22) are located at and penetrate the top wall24, and first and second fluid outlets23A,23B (collectively or singly, the outlet23) are located at and penetrate the bottom wall25. (Note, inlets and outlets can be located anywhere and pass through any wall, even the same wall of the vacuum chamber62. In addition, although the directional terms “top,” “bottom,” “vertical,” and the like are used to describe the embodiments shown, the terms are not meant to be limiting.) When flowing, fluid flows through the degasser60in the direction indicated by arrows64and through first and/or second separators68A,68B (collectively or singly, the separator68) constituted of a bundle of tubes, each tube comprising or being formed from separator material. The degasser60comprises a depressurizer such as a vacuum (not shown) that is connected to the vacuum chamber62via a vacuum port66. When the degasser60is in use, with one or more than one fluid flowing through one or more separators68A,68B, the pressure within the vacuum chamber62is reduced to a predetermined level, which may be between 10 mTorr to 150 Torr by evacuating the vacuum chamber62through the vacuum port66. The pressure of the fluid may be between 10 to 30 psig. The pressure differential draws the gas in the fluid through the tubes of the separators68A,68B that are permeable to the gas but not the liquid. The pressure across the tubes may be from 20 to 100 psi.

In the embodiment shown inFIG.2, the top wall24or the bottom wall25or both may be removable from the vacuum chamber62. Alternatively, the top wall24and/or the bottom wall25may be welded to the cylindrical wall63. In alternative embodiments, an opening (not shown) in the cylindrical wall63may be provided to access the vacuum chamber62and the one or more separators68A,68B contained in the vacuum chamber62. Preferably at least one of the top wall24or the bottom wall25is removable from the cylindrical wall63of the vacuum chamber62. In one embodiment, the top wall24and the bottom wall25may both be bolted to the opposite ends of the cylindrical wall63with a gasket (not shown), for example an O-ring (not shown), where the top wall24and one end163of the cylindrical wall63meet and a gasket where the bottom wall25and the opposite end263of the cylindrical wall63meet to provide an air-tight and liquid-tight seal.

The separator68A is shown comprising a plurality of tubes69A that are connected and are in fluid communication with the inlet22A and the outlet23A. The separator68B comprises a plurality of tubes69B that are connected and are in fluid communication with the inlet22B and the outlet23B. The separators68A,68B each further comprise connectors67attached at each end of the plurality of tubes69A,69B. Each of the connectors67may be threaded and may mate with oppositely threaded hollow connectors168attached at the ends of the inlets22A,22B and the outlets23A,23B adjacent to the separators68A,68B to provide for the flow of the fluid therethrough. Alternatively, any suitable connection device may be used as long as it provides an air-tight seal between the inlet22A,22B and one end of the tubes69A,69B and the outlet23A,23B and other end of the tubes69A,69B and provides for the flow of fluid therethrough. In the embodiment shown, the number of tubes69A,69B are typically between about 1 to about 125; the size of the tubes69A,69B may be from about 5 to about 25 feet (from about 152 to about 762 cm) in length and from about 0.025 to about 0.05 inches (from about 0.064 to about 0.13 cm) in wall thickness and the vacuum chamber62has a volume of 3 liters to 15 liters. In alternative embodiments the separator68may be a single tube or pipe.

The vacuum chamber62may be provided with vertical or horizontal support structures (not shown) to maintain the shape of the vacuum chamber62when the degasser60is in use and the pressure in the vacuum chamber62is reduced.

Processing fluid (not shown) flows through the vacuum chamber62of the degasser60while the vacuum chamber62is evacuated at the vacuum port66to reduce the pressure in the vacuum chamber62. As a result of this pressure differential, the entrapped or dissolved gas molecules in the fluid permeate through the tubes of the separator68and are evacuated through the vacuum port66. This process results in a substantially gas-free processing liquid at the downstream end of the degasser60.

The preferred material for the pipe is a synthetic fluoropolymer such as Teflon® (a trademark of E.I. duPont de Nemours & Co., Inc. of Wilmington, Del.). More preferably the material for the pipe is FEP Teflon® (the fluorinated ethylene propylene (FEP) form of Teflon®) although the perfluoroalkoxy (PFA) or polytetrafluoroethylene (PTFE) forms of Teflon® may also be adequate. PTFE is a highly stable thermoplastic tetrafluoroethylene homopolymer composed of at least 20,000 C2F4monomer units linked into very long unbranched chains. FEP Teflon® has the advantage that it provides separator tubes69A,69B which are porous enough to allow molecules of typical inert pressurizing gasses to pass through it while at the same time being impervious to the molecules of TEOS or other commercially available reactants. FEP is also suitable as it has enough structural strength to withstand the pressure differential across it when formed as a pipe of the dimensions described above. Furthermore, FEP is an industry-accepted material for use in semiconductor processing operations. It has been found that FEP is of a relatively high purity and does not outgas and inject impurities into any processing environment or the processing fluid. This is not necessarily true of other materials which would otherwise be suitable for use as a separator68in the degasser60of the invention.

FIG.2further illustrates a membrane76that surrounds the separators68A and68B in the vacuum chamber62. The membrane76has an opening78proximate the vacuum port66.FIG.2still further illustrates an optional low wattage heater80located inside the vacuum chamber62. The heater80functions, when desired, to raise the temperature of the membrane76by a few degrees, typically 10° Celsius, and thereby enhance its permeability.

Although not shown, it is envisaged that any embodiment of the degasser60of the invention could include a sensor to detect the failure of the separator68. This failure could occur, for instance, if the separator68disconnects from the connectors67or a tube69A,69B ruptures. Such failure can be detected, for example, by placing a liquid sensor in the bottom of the vacuum chamber62of the degasser60to sense any liquid accumulating as a result, for example, of a ruptured separator tube69A,69B. Alternatively, a pressure sensor could be placed near the vacuum port66or elsewhere as described below to detect any sudden changes of pressure within the vacuum chamber62which would occur in the event of tube failure or other failure associated with the separator68, such as a leak at a connection or in the inlet or outlet lines.

In the embodiment shown inFIG.2, the number of inlets22A,22B is equal to the number of separators68A,68B. Similarly, the number of outlets23A,23B is equal to the number of separators68A,68B. The same or different chemicals may be fed through the first flow path or train A through the vacuum chamber62comprising the inlet22A, the separator68A, and the outlet23A, and the second flow path or train B through the vacuum chamber62comprising the inlet22B, the separator68B, and the outlet23B. The inlet22A is connected to a source line38which is connected to a first source (not shown) for the first fluid and the inlet22B is connected to a source line39which is connected to the first source or to a second source (not shown) for the same first chemical (from either the first or second source) or a second chemical from the second source.

FIG.3shows an alternative embodiment of a degasser60of the invention comprising three separators68. In the embodiment of the degasser60shown inFIG.3, the number of inlets22is again equal to the number of separators68and the number of outlets23is also equal to the number of separators68. The degasser60comprises a housing100in which is located the vacuum chamber62, a pump83, one or more than one source lines into the housing100, one or more than one exit pipes out of the housing100, and valves and other lines to direct the one or more than one fluid (chemicals) to each of the separators68.

In the embodiment shown inFIG.3, there are first, second, and third separators68A,68B, and68C.FIG.3shows piping on the exterior of the vacuum chamber62upstream and downstream of the separators68A,68B,68C that may include multiple source lines and exit lines. On the inlet side of the separators68, as shown, the first and second source lines38,39are included upstream of the first, second, and third inlets22A,22B,22C that can be used to flow one or two different or the same fluid chemical streams to one or more than one of the separators68A,68B,68C. In addition, the degasser piping includes a feed line47that is downstream of the source lines and connects the one or more source lines to the first, second, and third separators68A,68B and68C, which in this embodiment is by connecting the feed line47at the first, second, and third junctions JA, JB, and JC to the inlets22A,22B and22C, respectively. (In alternative embodiments, the feed line47may be downstream of the inlets22and be located inside the vacuum chamber62.) The source line38, as shown, has a valve therein upstream of its connection J38with the feed line47. The source line39connects to the feed line47at a connection J39. The junctions, also referred to as connections, may be the same or different. Suitable junctions are, for example, two-way or three-way or four-way fittings.

Each of the inlets22A,22B,22C is connected to each of the separators68A,68B,68C, respectively, as described above forFIG.2. The feed line47may include one or more valves in it. As shown the feed line47has one valve37in it located between junctions JA and JB. Each of the first, second, and third inlets22A,22B,22C has a first, second, and third valve35A,35B, and35C, respectively, in them located downstream of the first, second, and third junctions JA, JB, and JC within the feed line47. If a single source of fluid is going to be used to flow fluid into the degasser60, then the valve37may be closed and the fluid will flow through the source line39and, depending upon the flow rate of that fluid to the degasser60, only one, two, or all three of the valves35A,35B, and35C will be open to allow the fluid to flow through one, two, or all three of the separators68A,68B,68C, respectively. If the flow rate from the single source of fluid is low, only one valve, for example, the valve35B will be open so the fluid will flow into the vacuum chamber62via the inlet22B which is fluidly connected to the separator68B. If the flow rate of the fluid in the source line39is large enough to require two separators, then the valve37may be (or will remain) closed and the flow of the fluid may be via the source line39to the feed line47, through the open valves35B and35C to the separators68B and68C, respectively. If on the other hand, the flow of fluid through the source line39is enough for three separators, then a valve29in the source line38will be closed; the valve37in the feed line47and the valves35A,35B, and35C in the inlets22A,22B, and22C will all be open and the fluid will flow into and through the separators68A,68B, and68C.

Downstream of the separators68A,68B,68C there is also optional piping provided in the degasser60as shown inFIG.3. As shown, the degasser60comprises the outlets23A,23B, and23C; the valves31A,31B, and31C in each of the outlets23A,23B, and23C, respectively; and a collection line41fluidly connected to the outlets23A,23B, and23C and fluidly connected to two exit lines48and49. The exit pipes48and49are connected to the collection line41via connectors J48and J49, respectively. The outlets23A,23B, and23C are connected via the junctions JD, JE, and JF, respectively, to the collection line41. The degasser60also comprises a valve40in the exit line48(downstream of the collection line41) and a valve33in the collection line41between junctions JD and JE. As described above for the embodiment shown inFIG.3, if the separator68B is the only separator through which fluid is flowing then the valve31B will be open and the valves33and31C may be closed to direct the degassed fluid into and through exit line49to the one or more tools (not shown) downstream of the degasser60. If the separators68B and68C are degassing the same fluid as earlier described, the valve33will be closed and the valves31B and31C will be open. If all three separators68A,68B, and68C are degassing fluid, and only one exit line is to be used, then the valve40will be closed and the valves31A,31B, and31C will be opened.

If more than one fluid source is used, then the source lines38and39will be used to flow fluid into the degasser60. The fluids degassed may be the same or different. If the fluids from the first and second fluid sources are the same, and all of the separators are on-line, then all of the valves upstream of the separators may be open. Alternatively, if the first and second fluids to be degassed are not the same, then the one or more separators used to degas the first fluid must be isolated from the one or more separators used to degas the second fluid. So, for example, if a first fluid flows into the degasser60via the source line38, and a second fluid flows into the degasser60via the source line39then the valve37in the feed line47and the valve33in the collection line41will be closed to isolate a first fluid train from a second fluid train. The first fluid in the first source line39will flow through the first junctions J39and JB, the first valve35B in the first inlet22B into the first separator68A, the first valve31A in the first outlet23A, the first junctions JD and J48, the valve40, and the first exit line48. The second fluid in the second source line39, if the valve35C connecting the feed line47to the third separator68C is closed, will flow to and through the second junctions J39and JB, the second valve35A, the second inlet22B into the second separator68B, and then to and through the second outlet23B, the second valve31B (preferable the valve31C will be closed), the second junctions JE and J49, the second valve40to and through the exit line48. If the flow rate of the second fluid is large enough, then the second fluid will flow through the second and third separators68B and68C. The second and third valves35B,35C in the second and third inlets22B and22C, respectively, will be open for the flow of the second fluid into the second and third separators68B,68C. In addition, the valves31B,31C downstream of the second and third separators68B,68C in the second and third outlets23B,23C will be open for the flow of the second fluid.

In the embodiment shown inFIG.4, the number of inlets22is fewer than the number of separators68. Similarly, the number of outlets23is fewer than the number of separators68. The degasser60shown inFIG.4is designed for a single chemical of increasing or decreasing flow rate to be degassed. The degasser60shown inFIG.4allows for an increase in the flow rate of a single chemical to be degassed without the capital cost and footprint requirements of adding a second degasser system. In the embodiment shown inFIG.4, the chemical to be degassed may be fed through a first flow path through the vacuum chamber62comprising the inlet22, the first separator68A, and the outlet23and/or the second flow path through the vacuum chamber62comprising the inlet22, the second separator68B, and the outlet23and/or the inlet22, the third separator68C, and the outlet23. The inlet22is connected to the source line38which is connected to a source (not shown) for the fluid. The outlet23is connected to an exit line which provides the degassed fluid to one or more tools (not shown).

In the embodiment shown inFIG.4, the degasser60comprises more than one separator (namely, first, second, and third separators68A,68B and68C), the inlet22, the feed line47, the collection line41, and the outlet23. In this embodiment, the first, second, and third separators68A,68B, and68C connect with the feed line47at the junctions JA, JB, and JC and with the collection line41at the junctions JD, JE, and JF. The feed line47and the collection line41are located in the interior of the vacuum chamber62upstream and downstream of the separators68A,68B,68C. (As shown, there is a single source line39, but as in the embodiment shown inFIG.3one or more additional source lines and inlets could be added to the present embodiment, if desired. In addition, if desired one or more of the feed line47and/or the collection line41could be located outside the vacuum chamber62.) The degasser piping includes the feed line47downstream of the source line39and in this embodiment, downstream of the one or more than one inlet22. (As was shown inFIG.3, the feed line47was upstream of the one or more than one inlet22on the exterior of the vacuum chamber62.) The feed line47connects the one or more than one source line39to the separators68, which in this embodiment is by connecting the feed line47at the junctions JA, JB, and JC to the first, second, and third separators68A,68B,68C.

The source line39connects to the feed line47at the connection J39. (The junctions and connections may be the same or different. One or more than one of two-way or three-way and/or four-way pipe fittings may be used for the junctions and connections and in this and the other embodiments, the junctions and connections can be positioned anywhere on the feed line47and the collection line41, not just as shown.) The junctions JA, JB, and JC in the feed line47may connect directly to each of the separators68A,68B,68C, respectively, or there may be some pipes or alternative fittings between one or more of the junctions JA, JB, and JC and the one or more separators68A,68B,68C, respectively. In some embodiments, quick release valves (not shown) may be included between one or more of the junctions JA, JB, and JC and one or more of the separators68A,68B,68C, respectively.

The feed line47may comprise one or more valves in it. As shown, the feed line47has one valve37located between junctions JA and JB (the junctions that are in fluid communication with the first and second separators68A and68B, respectively). As shown, the feed line47has a second valve57located between the junctions JB and JC (the junctions that are in fluid communication with the second and third separators68B and68C, respectively). The embodiment inFIG.4is designed so that the separator68B is always on-line if there is fluid flowing through the degasser60. The valves37and57can both be closed, both be open, or individually be opened and closed or closed and open, respectively, to prevent or allow the flow of fluid into both or each of the separators68A and68C, respectively, based on the volume of fluid to be degassed.

At the exit end of the separators68A,68B, and68C are junctions JD, JE, and JF with the collection line41. The collection line41may have one or more valves in it. Typically, the number of valves in the collection line41will match the number of valves in the feed line47. As shown, there is the valve33between the first and second junctions JD and JE, and a valve53between the second and third junctions JE and JF. When the separator68A is not on-line, that is when the valve37is closed, then the valve33will also be closed. When the separator68C is not on-line, that is when the valve57is closed, then the valve53will also be closed. After a period of operation, when the separator68B has been the only separator on-line (degassing fluid), if demand for the fluid increases or a second tool is brought on-line to which the same chemical fluid is fed, an additional separator or separators68A and/or68C may be brought on-line by opening the valve in the feed line and the corresponding valve in the collection line that will provide for the flow of fluid to and through the one or more separators. For the separator68A, the valves37and33will be opened, and/or for the separator68C, the valves57and53will be opened to provide the flow of fluid to be degassed to and through those separators.

In alternative embodiments the feed line47may be external to the vacuum chamber62and the collection line41may be internal to the vacuum chamber62and/or the feed line47may be internal to the vacuum chamber62and the collection line41may be external to the vacuum chamber62. Having the feed line47and collection line41internal to the vacuum chamber62may provide fewer inlets22and outlets23that must penetrate the one wall or more than one walls of the vacuum chamber62. Fewer penetrations through the walls decreases the chances of a leak in one of the penetrations. On the other hand, if the feed line47and/or the collection line41is located external to the vacuum chamber62, the vacuum chamber62can be decreased in size and if repairs need to be made to the feed line47and/or the collection line41or to the valves or valve controls in either or both of the feed line47and/or collection line41therein, then they are easier to access if located externally of the vacuum chamber62. If the feed line47and the collection line41are located inside the vacuum chamber62one or both of the top wall24and the bottom wall25may be removable and/or the vacuum chamber62may be provided with an access door (not shown) having an air-tight seal.

In an additional aspect of the invention, the separators68used in the degasser60may be designed to degas a certain volume of fluid, but the volumes of the separators68do not have to be equivalent. For example, standard separators may be made to degas, for examples, 0.5 volume of fluid/minute, 1 volume of fluid/minute, and 0.8 volume of fluid/minute. So, for example, if a separator is in use and is degassing 1 volume of fluid/minute and the end-user needs to increase the volume to 1.5, a 0.5 volume of fluid/minute separator can be brought on-line inside the same vacuum chamber62. In one embodiment, each separator68will comprise a plurality of tubes. To vary the volume of fluid that a separator can degas, the number of tubes can be increased or decreased for each separator. If the fluid demand increases from 1 volume of fluid/minute to 1.5 volume of fluid/minute, then the number of tubes used in a second separator brought on-line will be half the number of tubes in the separator that was already on-line.

In alternative embodiments any of the valves that isolate a separator that is not in use may be replaced with a plug (not shown) instead. Plugs can be provided when the separators, for example separators68A and68C, are not provided with the equipment when originally installed, but will allow for the easy replacement and installation of one or more than one of the separators68A,68C in fluid communication with the feed line47and the collection line41and optionally one or more than one of the valve pairs37and33or57and53in the feed line47and the collection line41, if the need for degassed fluid increases. In one embodiment, the degasser60may be installed with only a first or only first and second separators, for example, separator68B or separators68A and68B, and plugs (not shown) may be provided instead for either or both of the valves37or57and/or the valves33and53. The plugs will have to be removed and one or more separators installed into the degasser60before allowing fluid to flow into those separators.

FIG.5shows a schematic diagram of a degassing system having additional aspects. The degasser60is disposed between a source84for the fluid to be degassed (which is, as shown, a tank) and a point of use86of the fluid that has been degassed. The degasser60includes: the vacuum chamber62; the vacuum pump83(which is used to represent any decompression device that may be used) for decompressing the inside of the vacuum chamber62to a pressure lower than atmospheric pressure; a vacuum suction pipe that connects the vacuum pump83to the vacuum port66of the vacuum chamber62to form a vacuum line88; a pressure gauge82for measuring the pressure in the vacuum suction pipe88; and a liquid leakage sensor81located at a position closer to the vacuum chamber62than the position of the pressure gauge82in the vacuum line. The degasser system also comprises a control system98and a human-machine interface or HMI97and electrical and/or mechanical components to open and close valves and adjust the pump speed. The vacuum chamber62is installed in the degasser housing100in such a manner that the top wall24of the vacuum chamber62is oriented vertically upward, and the inlet22and the outlet23both pass through the top wall24, and the inlet22and the outlet23are both oriented vertically upward. An optional pump85removes the fluid held in the fluid source84and sends the fluid to the degasser60, and then sends the degassed fluid to the point of use86. The pump85may be omitted if the head of the fluid source84is otherwise pressurized resulting in fluid flow to the degasser60. Further in alternative embodiments the optional pump85and the fluid source84may be within the housing100, too.

In the degasser60shown inFIG.5, the pressure gauge82disposed on the vacuum line88between the vacuum chamber62and the vacuum pump83electrically communicates the amounts it measures to a control system98via a data transmitter99(hardwired, wireless, or otherwise) to check for fluctuation. The control system98uses that information to communicate with the vacuum pump83to cause the vacuum pump83to speed up or slow down. In the preferred embodiment, the pump83is a variable speed pump that makes it possible to maintain the same level of reduced pressure in the vacuum chamber62whether one or two or three or more separators68is/or are degassing fluid in the vacuum chamber62while reducing the wear of the vacuum pump83.

In addition, the degasser60may comprise the liquid leakage sensor81to determine if there is any leak in the vacuum chamber62that may be caused by, for example, a leaking tube in a tube bundle69A,69B or a leaking connector67. If a leak is detected, the degassing process should be stopped. The suitable types of liquid leakage sensor81are not limited. For example, a liquid leakage sensor81having two conducting wires to detect a change in resistance between the conducting wires, an ultrasonic liquid detector, or a liquid leakage sensor of the optical fiber type can be used. Moreover, a detector, such as the liquid leakage sensor81and a vacuum gauge, may be disposed in the vacuum chamber62of the degasser60.

As shown inFIG.5, a liquid trap89may be disposed on the vacuum line88between the vacuum chamber62and the vacuum pump83in the degasser60. The liquid trap89prevents the fluid to be degassed that has flowed into the vacuum line88via the vacuum port66from being drawn into the vacuum pump83and contacting the pressure gauge82. When thus configured, the pressure gauge82and the vacuum pump83can be protected from failure.

It is possible to use as the liquid trap89a small chamber capable of holding a liquid, and a component including a gas-permeable filter that allows a gas to permeate therethrough while preventing a liquid from permeating therethrough. A specific example of such a gas-permeable filter is a porous filter including a porous membrane made of fluororesin or polyolefin resin. Specifically, the liquid trap89is disposed between the liquid leakage sensor81and the vacuum pump83on the vacuum line88, preferably between the liquid leakage sensor81and the pressure gauge82.

The degassing system shown inFIG.5further comprises the flow meter118that measures the flow rate of the degassed fluid flowing therethrough and adjusts a control valve to increase or decrease the flow of the degassed fluid to the point of use86. If there is increased or decreased demand, the flow meter118will communicate with the control system98that will automatically open and close valves in the degasser60to flow fluid to one or more additional separators or one or more fewer separators in response to the demand for degassed fluid. In addition, the speed of the optional pump85may be adjusted in response to the control system98in response to the increased or decreased demand. Alternatively, the fluid flow may be adjusted manually (as compared to automatically) by opening closed valves in fluid communication with one or more than one separator68and directing fluid through the one or more than one separator68(optionally in response to sensors sensing or the manual increase in demand for the degassed fluid at the point of use86).

Alternatively, or in addition, the automatic or manual process of opening closed valves may be in response to the flow meter118or the rate of change of the fluid weight measured by a scale (not shown) measuring the weight of the fluid source84. In alternative embodiments, the scale and the source84of the fluid may optionally be located within the housing100, in addition to the pump85and optionally one or more of the flow meter118, the control valve128, and the vaporizer130. The fluid control valve128is in communication via the connection line126with the flow meter118.

The present invention has been described with reference to specific embodiments. Modifications may be apparent to those skilled in the art. Such modifications are included in the disclosure.