Fluid sump

Abstract

A fluid sump 200A for an abatement apparatus that is configured to abate an effluent stream from a semiconductor processing tool. The fluid sump comprises sump chamber 10A, sump conduit 70A and at least one capacitive level sensor 100A. The sump chamber is configured to retain fluid used by the abatement apparatus. The sump conduit is positioned externally to the sump chamber and the capacitive level sensor is positioned on the sump conduit. The sensor is configured to indicate when fluid is present within the sump conduit proximate the sensor. The sump may comprise controller 120A coupled to receive signals from the sensor and acts to provide a signal indicative of the fluid level in the sump chamber. If the fluid level is below a specific value, the controller can signal a source of the fluid to convey additional liquid to the sump. If the fluid level is found to exceed a higher upper level, the controller can signal a receptacle to receive excess fluid.

Description

FIELD OF THE INVENTION The field of the invention relates to a fluid sump for an abatement apparatus. 5 BACKGROUND Fluid sumps for an abatement apparatus are known. Such abatement apparatus may be configured to abate an effluent stream from a semiconductor processing tool. The fluid sump typically holds fluid which is recirculated within the 10 abatement apparatus. Although such fluid sumps are known, they can have undesirable consequences. Accordingly, it is desired to provide an improved fluid sump. SUMMARY 15 According to a first aspect, there is provided a fluid sump for an abatement apparatus configured to abate an effluent stream from a semiconductor processing tool, the fluid sump comprising: a sump chamber configured to retain fluid used by components of the abatement apparatus; a sump conduit in fluid communication with the sump chamber and positioned externally to the sump 20 chamber; and at least one capacitive level sensor positioned on the sump conduit and configured to indicate when the fluid is present within the sump conduit proximate the capacitive level sensor. The first aspect recognizes that a problem with existing fluid sumps is that it can 25 be difficult to reliably determine the level of the fluid within the sump. This is because the fluid can interfere with the operation of any level sensors since the fluid can contain particulates and / or can be corrosive. Accordingly, a fluid sump is provided. The fluid sump may be for an abatement apparatus. The abatement apparatus may be configured to abate an effluent stream from a semiconductor 30 processing tool. The fluid sump may comprise a sump chamber or housing. The sump chamber may be configured or arranged to retain, hold or receive fluid used or provided to components of the abatement apparatus. The fluid sump may comprise a sump conduit or tube. The sump conduit may be in fluid communication or coupled with the sump chamber. The sump conduit may be positioned externally to or outside of the sump chamber. The fluid sump may comprise at least one capacitive level sensor or other non-contact sensor. The 5 capacitive level sensor may be positioned or located on the sump conduit. The capacitive level sensor may be configured or arranged to indicate or signal when fluid is present within the sump conduit proximate or near to the capacitive level sensor. In this way, a non-contact technique is used to determine the fluid level within the sump chamber, with the fluid being conveyed within the sump conduit 10 and the presence of the fluid within the sump conduit being detected by the capacitive level sensor. This provides for reliable detection of the level of the fluid within the fluid sump without exposing the level sensor to direct contact with the fluid, which avoids the problems of any particulates within the fluid or the corrosive nature of the fluid. 15 The sump conduit may be orientated or located to extend between or encompass at least a specified lower level of the fluid within the sump chamber and a specified upper level of the fluid within the sump chamber. Hence, the fluid being present at the lower level and / or the upper level can be detected within the sump 20 conduit. The sump conduit may extend between a lower aperture in or defined by the sump chamber and an upper aperture in or defined by the sump chamber. The apertures may provide for fluid communication between the sump chamber and 25 the sump conduit. The lower aperture may be positioned below the specified lower level of the fluid within the sump chamber and the upper aperture is positioned above specified upper level of the fluid within the sump chamber. 30 The sump conduit may be a U-shaped tube extending between the lower aperture and the upper aperture. The sump conduit may be fluidly sealed with the sump chamber. The sump conduit may be is non-conductive. 5 The sump conduit may be non-reactive with the fluid. The sump conduit may be made from polypropylene or other suitable polymer. 10 The fluid sump may comprise a plurality of the capacitive level sensors, each located at a different position on the sump conduit. This enables the fluid level to be sensed at multiple different positions. One of the plurality of the capacitive level sensors may be located at the specified 15 lower level of the fluid in the sump chamber. One of the plurality of the capacitive level sensors may be located at the specified upper level of the fluid in the sump chamber. 20 One of the plurality of the capacitive level sensors may be located at a specified higher upper level above the specified upper level of the fluid in the sump chamber. The fluid sump may comprise a controller coupled to receive signals from at least 25 one of the capacitive level sensors, the controller may be configured to provide at least one signal indicative of a fluid level of the fluid within the sump chamber. The controller may be configured to signal a source of the fluid to convey additional fluid to the sump chamber when the controller determines from the 30 capacitive level sensors that a fluid level within the sump chamber is below the specified lower level. The controller may be configured to signal a source of the fluid to cease conveying additional fluid to the sump chamber when the controller determines from the capacitive level sensors that a fluid level within the sump chamber is between the specified lower level and the specified upper level. 5 The controller may be configured to signal when the controller determines from the capacitive level sensors that a fluid level within the sump chamber exceeds the specified upper level. 10 The controller may be configured to signal a receptacle of the fluid to receive excess fluid from the sump chamber when the controller determines from the capacitive level sensors that a fluid level within the sump chamber exceeds the specified higher upper level. 15 The sump chamber may comprise a sump wall having an inner surface retaining the fluid, the sump wall defining the lower aperture and the upper aperture extending between the inner surface and an outer surface, and the sump conduit may extend from the outer surface. 20 The sump chamber may be configured to be received as a base of the abatement apparatus. According to a second aspect, there is provided an abatement apparatus comprising the fluid sump of the first aspect. 25 The abatement apparatus may comprise the optional features of the fluid sump set out above. Further particular and preferred aspects are set out in the accompanying 30 independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims. Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function. 5 BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which: FIG. 1 illustrates schematically a fluid sump for an abatement apparatus io according to one embodiment; and FIG. 2 illustrates schematically a fluid sump for an abatement apparatus according to one embodiment. DESCRIPTION OF THE EMBODIMENTS 15 Before discussing the embodiments in any more detail, first an overview will be provided. Some embodiments provide a level sensing technique for an abatement apparatus sump. Typically, the sump is provided with a conduit which receives fluid from the sump and on which is positioned one or more capacitive or other non-contact level sensors. This provides for a particularly reliable and 20 efficient technique for measuring the fluid level within the sump, particularly when that fluid contains particulates which can accumulate to impair the operation of a mechanical sensor and / or is corrosive, since this arrangement prevents direct contact between the fluid and the sensor. Likewise, this approach avoids the need to access within the sump when maintaining, replacing or calibrating the 25 level sensors. Also, this approach conveniently enables multiple sensors to be easily located to measure multiple levels within the sump. FIG. 1 illustrates schematically a fluid sump having a sump chamber 10A for an abatement apparatus 200A according to one embodiment. The sump chamber 30 10A is typically positioned below an abatement assembly 20A and below a packed tower 30A. Typically, the abatement assembly 20A receives an effluent stream or process stream 40 from a semiconductor processing tool (not shown). The abatement assembly 20A abates the effluent stream and exhausts an abated effluent stream 50 into the packed tower 30A via the sump chamber 10A. The abated effluent stream 50 is conveyed through the packed tower 30A and exits the packed tower 30A as an exhaust stream 60. 5 The sump chamber 10A acts as a repository for fluid used within the abatement assembly 20A and / or the packed tower 30A. Hence, the sump chamber 10A is located at the base of the abatement assembly 20A and the packed tower 30A with the fluid flowing into the sump chamber 10A typically due to gravity. The io sump chamber 10A is configured to maintain a level of fluid within the sump chamber 10A between a lower or minimum level L1 and an upper or maximum level L2. A sump conduit 70A extends from an external surface of the sump chamber 10A. In particular, the sump chamber 10A has an upper aperture or opening 80A and a lower aperture or opening 90A within a wall of the sump 15 chamber 10A. The upper aperture 80A is located above the upper level L2 and the lower aperture 90A is located below the lower level L1. The sump conduit 70A is coupled with the upper aperture 80A and the lower aperture 90A to be in fluid communication with the fluid within the sump chamber 10A. 20 Located on an external surface of the sump conduit 70A are an upper level sensor 100A and a lower level sensor 110A. The upper level sensor 100A and the lower level sensor 110A are capacitive level sensors. The upper level sensor 100A is positioned to align with the upper level L2, while the lower level sensor 110B is positioned to align with the lower level L1. The upper level sensor 100A 25 and the lower level sensor 110A are both coupled with a controller 120A. In operation, the fluid level within the sump chamber 10A is monitored. In particular, when the fluid level within the sump chamber 10A fails to achieve the lower level L1 then both the lower level sensor 110A and the upper level sensor 30 100A indicate that no fluid is present within the sump conduit 70A in the vicinity of those sensors and the fluid level is below a minimum level. Accordingly, the controller 120A may operate to introduce further fluid into the sump chamber 10A from a fluid source (not shown) and / or provide an indication that the fluid level within the sump chamber 10A is below the lower level L1. When the fluid level within the sump chamber 10A is between the lower level L1 and the upper level L2, then the lower level sensor 110A will indicate that fluid is present within the 5 sump conduit 70A in the vicinity of the lower level sensor 110A, but the upper level sensor 100A will indicate that no fluid is present within the sump conduit 70A in the vicinity of the upper level sensor 100A. The controller 120A may then indicate that the fluid within the sump chamber 10A is within a normal operating level between the minimum and a maximum level. When the fluid within the io sump chamber 10A exceeds the upper level L2, then the lower level sensor 110A indicates that fluid is present within the sump conduit 70A in the vicinity of the lower level sensor 110A and the upper level sensor 110A will indicate that fluid is present within the sump conduit 70A in the vicinity of the upper level sensor 100A. Accordingly, the controller 120A may operate to remove fluid from the 15 sump chamber 10A to a fluid repository (not shown) and / or provide an indication that the fluid within the sump chamber 10A exceeds the maximum level. FIG. 2 illustrates schematically a fluid sump having a sump chamber 10B for an abatement apparatus 200B according to one embodiment. The sump chamber 20 10B is typically positioned below an abatement assembly 20A and below a packed tower 30A. Typically, the abatement assembly 20A receives an effluent stream or process stream 40 from a semiconductor processing tool (not shown). The abatement assembly 20A abates the effluent stream and exhausts an abated effluent stream 50 into the packed tower 30A via the sump chamber 10B. The 25 abated effluent stream 50 is conveyed through the packed tower 30A and exits the packed tower 30A as an exhaust stream 60. The sump chamber 10B acts as a repository for fluid used within the abatement assembly 20A and / or the packed tower 30A. Hence, the sump chamber 10B is 30 located at the base of the abatement assembly 20A and the packed tower 30A with the fluid flowing into the fluid sump 10B typically due to gravity. The sump chamber 10B is configured to maintain a level of fluid within the sump chamber 10B between a lower or minimum level L1 and a higher upper or higher maximum level L3. A sump conduit 70B extends from an external surface of the sump chamber 10B. In particular, the sump chamber 10B has a higher upper aperture or opening 85B, an upper aperture or opening 80B and a lower aperture or 5 opening 90B within a wall of the sump chamber 10B. The higher upper aperture 85A is located above the upper level L3, the upper aperture 80B is located above the upper level L2 and the lower aperture 90B is located below the lower level L1. The sump conduit 70B is coupled with the higher upper aperture 85B and the lower aperture 90B to be in fluid communication with the fluid within the sump io chamber 10B. Located on an external surface of the sump conduit 70B are a higher upper level sensor 105B, an upper level sensor 100B and a lower level sensor 11 OB. The higher upper level sensor 105B, the upper level sensor 100B and the lower level 15 sensor 110B are capacitive level sensors. The higher upper level sensor 105B is positioned to align with the higher upper level L3, the upper level sensor 100B is positioned to align with the upper level L2, while the lower level sensor 110B is positioned to align with the lower level L1. The higher upper level sensor 105B, the upper level sensor 100B and the lower level sensor 110B are all coupled with 20 a controller 120B. In operation, the fluid level within the sump chamber 10B is monitored. In particular, when the fluid level within the sump chamber 10B fails to achieve the lower level L1 then the lower level sensor 110B, the upper level sensor 100B and 25 the higher upper level sensor 105B indicate that no fluid is present within the sump conduit 70B in the vicinity of those sensors and the fluid level is below a minimum level. Accordingly, the controller 120B may operate to introduce further fluid into the sump chamber 10B from a fluid source (not shown) and / or provide an indication that the fluid level within the sump chamber 10B is below the lower 30 level L1. Wien the fluid level within the sump chamber 10B is between the lower level L1 and the upper level L2, then the lower level sensor 110B will indicate that fluid is present within the sump conduit 70B in the vicinity of the lower level sensor 110B, but the upper level sensor 100B and the higher upper level sensor 105B will indicate that no fluid is present within the sump conduit 70B in the vicinity of those sensors. The controller 120B may then indicate that the fluid within the sump chamber 10B is within a normal operating level between the 5 minimum and a maximum level. When the fluid within the sump chamber 10B exceeds the upper level L2, then the lower level sensor 110B indicates that fluid is present within the sump conduit 70B in the vicinity of the lower level sensor 110B, the upper level sensor 110B will indicate that fluid is present within the sump conduit 70B in the vicinity of the upper level sensor 100B, but the higher io upper level sensor 105B will indicate that no fluid is present within the sump conduit 70B in the vicinity of the higher upper level sensor 105B. Accordingly, the controller 120B may provide an indication that the fluid within the sump chamber 10B exceeds the maximum level. When the fluid within the sump chamber 10B exceeds the higher upper level L3, then the lower level sensor 15 110B indicates that fluid is present within the sump conduit 70B in the vicinity of the lower level sensor 110B, the upper level sensor 110B will indicate that fluid is present within the sump conduit 70B in the vicinity of the upper level sensor 100B and the higher upper level sensor 105B will indicate that fluid is present within the sump conduit 70B in the vicinity of the higher upper level sensor 105B. 20 Accordingly, the controller 120B may operate to remove fluid from the sump chamber 10B to a fluid repository (not shown) and / or provide an indication that the fluid within the sump chamber 10B exceeds the higher maximum level. Hence, some embodiments provide a capacitance liquid level sensor in an 25 abatement apparatus. The water tank or sump the abatement apparatus is used to collect wastewater, so it is hard to avoid powder in that water. The capacitance level sensor or other non-contact level sensor is used instead of a conventional float sensor whose operation is triggered by rotation to avoid the sensor becoming stuck with powder by directly contacting with liquid which 30 reduces the operational lifetime of the abatement apparatus and increases cost. The capacitance level sensor is a good choice when the tank material is polypropylene (PP) and is suited to detecting the water out of the tank. A U-tube design is fitted to holes in the tank on which can be installed capacitance level sensors. The signals from the sensors can be routed to a programmable logic controller through a relay, which is easy to operate. 5 Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their 10 equivalents. REFERENCE SIGNS Sump chamber 10A;10B Abatement assembly 20A 5 Packed tower 30A Process stream 40 Abated effluent stream 50 Exhaust stream 60 Sump conduit 70A; 70B io Upper aperture 80A Higher upper aperture 85B Lower aperture 90A; 90B Upper level sensor 100A; 100B Higher upper level sensor 105B 15 Lower level sensor 110A; 110B Controller 120A; 120B Lower level L1 Upper level L2 Higher upper level L3 20 Abatement apparatus 200A; 200B

Claims

1. A fluid sump for an abatement apparatus configured to abate an effluent stream from a semiconductor processing tool, said fluid sump comprising:5 a sump chamber configured to retain fluid used by components of saidabatement apparatus;a sump conduit in fluid communication with said sump chamber and positioned externally to said sump chamber; andat least one capacitive level sensor positioned on said sump conduit and io configured to indicate when said fluid is present within said sump conduit proximate said capacitive level sensor.

2. The fluid sump of claim 1, wherein said sump conduit is orientated to extend between at least a specified lower level of said fluid within said sump15 chamber and a specified upper level of said fluid within said sump chamber.

3. The fluid sump of claim 1 or 2, wherein said sump conduit extends between a lower aperture in said sump chamber and an upper aperture in said sump chamber.

204. The fluid sump of claim 3, wherein said lower aperture is positioned below said specified lower level of said fluid within said sump chamber and said upper aperture is positioned above specified upper level of said fluid within said sump chamber.

255. The fluid sump of claim 3 or 4, wherein said sump conduit is at least one of:a U-shaped tube extending between said lower aperture and said upper aperture;30 fluidly sealed with said sump chamber;non-conductive;non-reactive with said fluid; andmade from polypropylene.

6. The fluid sump of any preceding claim, comprising a plurality of said capacitive level sensors, each located at a different position on said sump5 conduit.

7. The fluid sump of claim 6 when dependent on claim 2, wherein one of said plurality of said capacitive level sensors is at least one of:located at said specified lower level of said fluid in said sump chamber;io located at said specified upper level of said fluid in said sump chamber;andlocated at a specified higher upper level above said specified upper level of said fluid in said sump chamber.15 8. The fluid sump of any preceding claim, comprising a controller coupled toreceive signals from at least one of said capacitive level sensors and configured to provide at least one signal indicative of a fluid level of said fluid within said sump chamber.20 9. The fluid sump of claim 8, wherein said controller is configured to signal asource of said fluid to convey additional fluid to said sump chamber when said controller determines from said capacitive level sensors that a fluid level within said sump chamber is below said specified lower level.25 10. The fluid sump of claim 8 or 9, wherein said controller is configured tosignal a source of said fluid to cease conveying additional fluid to said sump chamber when said controller determines from said capacitive level sensors that a fluid level within said sump chamber is between said specified lower level and said specified upper level.3011. The fluid sump of any one of claims 8 to 10, wherein said controller is configured to signal when said controller determines from said capacitive levelsensors that a fluid level within said sump chamber exceeds said specified upper level.

12. The fluid sump of any one of claims 8 to 11, wherein said controller is 5 configured to signal a receptacle of said fluid to receive excess fluid from said sump chamber when said controller determines from said capacitive level sensors that a fluid level within said sump chamber exceeds said specified higher upper level.io 13. The fluid sump of any one of claims 3 to 12, wherein said sump chamber comprises a sump wall having an inner surface retaining said fluid, said sump wall defining said lower aperture and said upper aperture extending between said inner surface and an outer surface, and said sump conduit extends from said outer surface.1514. The fluid sump of any preceding claim, wherein said sump chamber is configured to be received as a base of said abatement apparatus.

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