Liquid filtration devices for gas / solid separation in semiconductor processing

Abstract

A liquid filtration device for gas / solid separation includes a housing having a filtration chamber, a semiconductor process gas inlet, and a process gas outlet. The filtration chamber forms a liquid reservoir, and the semiconductor process gas inlet and the process gas outlet communicate with the filtration chamber. The housing also includes a filtrate inlet and a filtrate outlet, both of which communicate with the liquid reservoir for respectively delivering and discharging filtered fluid to and from the liquid reservoir.

Description

[0001] Technical Field and Background

[0002] Typically, the manufacture of semiconductor devices employs conversions by oxidation, for example, at moderate to highly elevated silicon wafer temperatures using certain chemicals, to form the desired thin films that comprise the circuit layers of the semiconductor devices. For example, in a chemical vapor deposition (CVD) process, silicon dioxide films deposited on silicon wafers are formed by oxidizing silane with oxygen at a wafer temperature of approximately 400 degrees Celsius and a process chamber pressure of approximately 300 mTorr. Silicon dioxide films are also deposited by oxidizing vaporized tetraethylsiloxane (TES) with oxygen and ozone under similar process conditions. Silicon oxide films are also deposited at lower temperatures using low-pressure plasma-enhanced chemical vapor deposition (PECVD). In another process, silane reacts with ammonia at low pressure and moderate wafer temperatures to form silicon nitride. In these and nearly all other CVD reactions, such as the formation of tungsten and tungsten silicide films, nearly 75% of the gaseous feed reactants entering the process chamber pass through the chamber unconverted.

[0003] The exhaust from a typical semiconductor processing chamber is a low-pressure gas stream consisting of unconverted feed reactants, reaction byproducts, a diluent nitrogen carrier gas, and particulates. These particulates, which are byproducts of the gas-phase reactions of the heated reactants, continue to form and increase in number along the foreline, which runs between the process chamber and the vacuum pump and can reach up to 60 feet in a typical manufacturing facility. Figure 1 is a schematic diagram of a typical CVD or PECVD system, which consists of a process chamber connected to a vacuum pump via a vacuum foreline. The vacuum pump is connected via an exhaust line to a typical exhaust abatement system, which uses a natural gas flame to destroy unreacted process gases and then uses a gas / water absorption column to remove acidic gaseous byproducts. The output of this abatement system includes an acidic wastewater stream, which is typically neutralized and discharged, and a gas stream laden with fine particles, which is discharged to the atmosphere after passing through a large-surface-area mechanical particulate filter.

[0004] Particles coat all connecting lines between the process chamber, vacuum pump, and abatement system and often fill and clog these lines, resulting in significant maintenance downtime that significantly increases operating costs. In many cases, vacuum pumps must be shut down due to the heavy particle deposition that renders them inoperable. Removing and replacing vacuum pumps from these lines often incurs extremely high material and labor costs. In a few processes, mechanical filters are placed in the vacuum foreline to capture these particles in order to extend the life of the vacuum pump. In many cases, both the foreline and the pump exhaust line are heated to prevent condensation of unconverted condensable reactants, which then helps to absorb and agglomerate carrier gas particles and create liquid / solid blockages that are expensive and difficult to clean.

[0005] Particle separation from a particle-laden gas stream is best achieved using a liquid medium. For example, particles can be separated from large gas flows by passing the particle-laden gas stream through a very high-flow water shower. By properly adjusting the vessel volume and water flow rate, high particle separation into the water stream can be achieved. While such separation processes using water are effective and economical, they cannot be used in semiconductor processing due to potential adverse water chemistry reactions with reactants in the gas stream and the very high water vapor pressures in the low-pressure foreline. In vacuum CVD and PECVD semiconductor processes, molecular water in the foreline can diffuse back into the process chamber itself and degrade the chemical composition of the semiconductor film being processed. Summary of the Invention

[0006] Therefore, a liquid filtration apparatus is provided that uses a liquid as a medium to separate particles from a carrier gas particle stream in a low pressure foreline of a CVD and PECVD semiconductor process. Suitable filter liquids have a particle size of less than about 10 -7 Torr, for example, the commercially available Fomblin liquid with the chemical name perfluoropolyether (PFPE) has a vapor pressure of about 6×10 -8 Torr or less. Suitable liquids, such as PFPE, are chemically inert, can be used at temperatures ranging from -58°C to as high as 257°C, and exhibit negligible outgassing under high vacuum operation. They are non-conductive, with a dielectric strength of approximately 15.7 MV / m. They can be formulated with kinematic viscosities ranging from 38 to 1830 cSt. For reference, the kinematic viscosity of water is 1 cSt.

[0007] In one embodiment, a liquid filtration apparatus for gas / solid separation includes a housing having a filtration chamber, a semiconductor process gas inlet, and a process gas outlet. The chamber forms a liquid reservoir, and the semiconductor process gas inlet and the process gas outlet communicate with the filtration chamber. The housing also includes a filtered liquid inlet and a filtered liquid outlet, which communicate with the liquid reservoir and are used to deliver filtered fluid to and discharge filtered fluid from the liquid reservoir, respectively.

[0008] In one aspect, the semiconductor process gas inlet is in line with the process gas outlet. For example, the housing can include an exhaust chamber between the liquid reservoir and the process gas outlet, wherein filtered process gas can be exhausted before exiting the housing through the process gas outlet.

[0009] In another aspect, the liquid filtering device further includes a feed pipe connected to the process gas inlet and extending into the filtered liquid in the reservoir, so as to directly inject the process gas flowing through the process gas inlet into the filtered liquid in the liquid reservoir.

[0010] For example, when the housing has an exhaust chamber between the liquid reservoir and the process gas outlet, the housing may include an internal conduit in fluid communication with the filter chamber and the exhaust chamber to direct filtered process gas from the filter chamber to the exhaust chamber.

[0011] In another aspect, the feeding tube comprises a perforated feeding tube.For example, the perforated feeding tube can include a plurality of perforations at its distal portion.

[0012] In another aspect, in any of the above devices, the liquid filtration device further comprises a filtered liquid control system for controlling the flow of filtered liquid into and out of the liquid reservoir. For example, the filtered liquid control system may include a controller and a fluid circuit, wherein the controller controls the fluid circuit to adjust the flow rate of filtered liquid into and out of the liquid reservoir, and the controller is configured to maintain a certain liquid level of the filtered liquid in the liquid reservoir.

[0013] In another aspect, a liquid filtration apparatus includes a feed tube having a venturi restriction and a venturi inlet therein, the venturi inlet being in fluid communication with a semiconductor process gas inlet or a liquid filter inlet for drawing process gas or filtered liquid into the feed tube.

[0014] On the other hand, the liquid filtering device also includes a filtered liquid control system for controlling the flow of filtered liquid into and out of the liquid reservoir, the filtered liquid control system includes a controller and a fluid circuit, wherein the controller controls the fluid circuit for adjusting the flow rate of filtered liquid into and out of the liquid reservoir, and is configured to maintain the liquid height of the filtered liquid in the liquid reservoir.

[0015] In one aspect, the filtered liquid control system includes a pump in fluid communication with the filtered liquid inlet to pump the filtered liquid into the liquid reservoir. In another aspect, the filtered liquid inlet is in fluid communication with the liquid reservoir via a feed tube, wherein the pump is configured to circulate the filtered liquid into the liquid reservoir via the feed tube.

[0016] In other aspects, the housing includes one or more optical windows for viewing the chamber.

[0017] According to yet another embodiment, a method of separating solids from a semiconductor process gas includes the steps of directing the semiconductor process gas into a flow of filtered liquid or a reservoir containing filtered liquid, thereby filtering the process gas, and exhausting the filtered process gas.

[0018] In one aspect, the directing step includes bubbling the semiconductor process gas into the filtered liquid in the reservoir.

[0019] In another aspect, the filtered liquid is circulated through the reservoir, thereby removing the particle-laden filtered liquid.

[0020] According to yet another aspect, the method includes forming a filtered fluid into a venturi flow and using the venturi flow to draw a semiconductor process gas into the filtered liquid flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic diagram of a prior art CVD or PECVD system comprising a process chamber connected to a vacuum pump via a front line;

[0022] Figure 2 is a schematic diagram of a first embodiment of a liquid filtration apparatus for separating solids from semiconductor process gases;

[0023] Figure 3 is a schematic diagram of a second embodiment of a liquid filtration apparatus for separating solids from semiconductor process gases;

[0024] Figure 4 is a schematic diagram of a third embodiment of a liquid filtration apparatus for separating solids from semiconductor process gases;

[0025] Figure 5 is a schematic diagram of a fourth embodiment of a liquid filtration apparatus for separating solids from semiconductor process gases;

[0026] Figure 5A is a similar Figure 5 A view showing the sequence of valve opening;

[0027] Figure 5B is a similar Figure 5 A view showing the sequence of valve opening;

[0028] Figure 5C is a similar Figure 5 A view showing the sequence of valve opening;

[0029] Figure 5D is a similar Figure 5 A view showing the sequence of valve opening;

[0030] Figure 6 is a schematic diagram of a fourth embodiment of a liquid filtration device, showing the filtration device installed in a semiconductor processing system;

[0031] Figure 7 FIG. 1 is a schematic diagram of a fourth embodiment of a liquid filtration apparatus, showing a filtration apparatus constituting a multi-chamber apparatus for a semiconductor processing system. DETAILED DESCRIPTION

[0032] refer to Figure 2Reference numeral 10 generally designates a liquid filtration device that may be placed in a foreline of a semiconductor processing chamber exhaust and is configured to filter solids or particles from semiconductor process gas exhausted from the semiconductor processing chamber and typically laden with solids or particles as byproducts of gas-phase reactions during the semiconductor process. Filter device 10 includes a housing 12 having a process gas inlet 14 and a gas outlet 16. Process gas inlet 14 is configured to receive semiconductor process gas flowing from the semiconductor processing chamber, typically laden with solids or particles, and gas outlet 16 is configured to discharge the filtered process gas after a filtration process as follows.

[0033] Housing 12 is formed of an inert material, such as aluminum, quartz, polymers, and typically stainless steel alloys, and includes a filter chamber 18 that receives process gas from a semiconductor processing chamber through inlet 14 and from which filtered gas is discharged through outlet 16. Filter chamber 18 forms a liquid reservoir 20 for holding a filter liquid that filters solids or particles from the process gas flowing into the filter device. Suitable filter liquids for removing or filtering solids or particles from semiconductor process gas that do not chemically react with reactants in the process gas stream have been found to include those having a vapor pressure of less than about 10 -7 Torr and is chemically inert. Suitable liquids include liquids that can be used in a temperature range of -58 degrees Celsius to +257 degrees Celsius and have negligible outgassing. Suitable liquids include non-conductive liquids with a dielectric strength in the range of 15.7 MV / m. In addition, suitable liquids have a kinematic viscosity greater than that of water (for reference, the kinematic viscosity of water is 1 cSt), for example, a kinematic viscosity in the range of 38 to 1830 cSt. For example, suitable liquids include commercially available Fomblin liquids or perfluoropolyether (PFPE). PFPE has a kinematic viscosity of approximately 6×10 -8 Torr or less vapor pressure and are chemically inert. PFPE can be used in a temperature range of -58°C to +257°C with negligible outgassing. PFPE has a dielectric strength of approximately 15.7 MV / m, is chemically inert, and can be used in a temperature range of -58°C to +257°C with negligible outgassing. They can be formulated to have kinematic viscosities ranging from 38 to 1830 cSt, for example. However, PFPE is an expensive liquid, so particle-laden PFPE liquid can be sent to a commercial purifier and recycled.

[0034] As described more fully below, the liquid level in the liquid reservoir 20 can be maintained by a control system to ensure that the process gas is immersed in the filtered liquid, as described more fully below. For example, the height of the liquid in the container 20 can be in the range of 3 inches to 8 inches, or 1 inch to 3 inches, or generally 2 inches to 6 inches, depending on the configuration of the filter device. The filter size and PFPE volume depend on the specific semiconductor process and chemical composition.

[0035] Filtered liquid is delivered to and removed from the liquid reservoir 20 via a filtered liquid inlet 22 and a filtered liquid outlet 24, which communicate with the liquid reservoir via conduits (e.g., pipes) connected to a common port 26 on the housing 12 for delivering and removing filtered fluid from the reservoir, respectively. Furthermore, as will be described more fully below, in one embodiment, the filtered liquid can be circulated through the apparatus 10 to increase interaction between the filtered liquid and the process gas.

[0036] Reference again Figure 2 As shown in the figure, the device 10 further includes a feed pipe 30, which is connected to the process gas inlet 14 and extends into the filtered liquid in the reservoir 20, so as to directly inject the process gas flowing through the process gas inlet into the liquid in the liquid reservoir.

[0037] The feed tube 30 is made of an inert material such as aluminum, quartz, polymer and typically a stainless steel alloy and optionally includes a plurality of perforations 32 at its distal end 30a, which is sealed at its distal end to direct all of the flowing process gas through the perforations to create a bubbling effect with the process gas in the rising fluid. The size, number and location of the perforations can vary, but can range from 0.125 inches in diameter to 0.5 inches or larger, or about 0.25 inches in diameter. The purpose of the holes is to effectively disperse the particle-laden gas stream and thoroughly mix it with the filtrate. The bubbles generated by the gas flowing out of the perforations mix with the filtrate, and the particles are separated from the gas stream and adsorbed into the filtrate without causing any harmful backflow to the semiconductor processing chamber.

[0038] As described above, the liquid filtration apparatus 10 may include a filtered liquid control system 50 for controlling the flow of filtered liquid into and out of the reservoir 20. For example, the filtered liquid control system 50 may include a controller 50a, such as a microprocessor, and a fluid circuit 28. The controller 50a controls the fluid circuit via electrically controlled valves 28a and 28b and a pump (e.g., a centrifugal pump or a magnetically coupled pump, not shown) to regulate the flow of filtered liquid through the inlet 22 and outlet 24 and into and out of the liquid reservoir 20. As described above, the filtered liquid control system 50 may also be configured to maintain the filtered liquid at a certain level within the liquid reservoir. In this manner, when the liquid is "used up," i.e., when it has reached a certain absorption level, it can be replaced with new filtered liquid. For example, when the filtered liquid is empirically deemed to be saturated with particles, it may be necessary to circulate fresh filtered liquid into the reservoir, or it may be necessary to circulate the fluid regardless of how many particles it has already absorbed.

[0039] In one embodiment, control system 50 includes one or more sensors 52. Sensors 52 can be used to detect the level of the filtered liquid or measure the opacity or other properties of the liquid, which can be used to indicate that the liquid has reached a certain particle absorption level. For example, determining when the liquid has reached a certain particle absorption level can be based on another property of the liquid, such as viscosity. Alternatively, two types of sensors can be used—one that measures the height of the filter liquid and another that measures a property of the liquid to indicate when the liquid has reached a desired particle absorption level. In either or both cases, control system 50 can be used to adjust the flow of filtered fluid into and out of liquid reservoir 20 based on the one or more sensors to adapt to the output of the semiconductor chamber and / or optimize the filtration process.

[0040] The device 10 can optionally include one or more optical windows 40 for observing the chamber 18. For example, the window 40 can be formed of heat-resistant glass or quartz material and extend into and through the wall of the housing 12. The window can be located below the desired filtered liquid level so that the height and / or opacity or other characteristics of the liquid can be manually observed to manually control the filtering device when needed. The window 40 can include a manual or automatic optical window and can be used to empirically assess the entrained solids content in the filtered liquid and trigger a manual or automatic withdrawal of a certain liquid volume and the addition of fresh filter liquid via valves 28a, 28b for continuous dynamic filtration operation without interrupting the processing chamber or production. For example, the valves (e.g., valves 28a, 28b) noted above can provide manual control, including manual override control, overriding the electric valve so that the operator can manually control the device 10.

[0041] In the illustrated embodiment, the process gas inlet 14 and the gas outlet 16 are located on the top and side of the housing 12 so that they have a substantially ninety degree (right angle) orientation; however, as will be described with reference to a second embodiment, the gas inlet 14 and the gas outlet 16 can be rearranged so that they are generally in a straight line.

[0042] In operation, a process gas stream enters the top of the apparatus 10, as shown, and passes through feed tube 30, bubbling through the filtrate in reservoir 20 where it sheds its particles and exits the filtrate reservoir 20. The filtered gas then exits the apparatus 10 laterally through gas outlet 16.

[0043] refer to Figure 3 Reference numeral 110 generally designates another or second embodiment of a liquid filtration apparatus that can be placed in a foreline of a semiconductor processing chamber exhaust and is configured to filter solids or particulates from semiconductor process gases exhausted from the semiconductor processing chamber. Similar to the previous embodiment, filtration apparatus 110 includes a housing 112 having a process gas inlet 114 for receiving semiconductor inflow process gas from the semiconductor processing chamber, which is typically laden with solids or particulates, and a gas outlet 116 for discharging the filtered process gas after the filtration process described below. Details of suitable materials for the housing structure are provided with reference to the first embodiment.

[0044] Figure 3 As best shown in FIG. 1 , the housing 112 further includes a filter chamber 118 that receives process gas via a process gas inlet 114 and discharges filtered gas from the filter chamber via a gas outlet 116. The filter chamber 118 forms a liquid reservoir 120 for holding a filter liquid that filters solids or particles from the process gas flowing into the filter device. For examples of suitable liquid properties and suitable liquids for filtering solids or particles from semiconductor process gases, see the first embodiment.

[0045] In the illustrated embodiment, the process gas inlet 114 and the gas outlet 116 are generally aligned. To this end, the housing 120 includes an exhaust chamber 138 between the liquid reservoir 120 and the gas outlet 116 to allow filtered gas to be exhausted from the interior of the filter chamber before exiting through the gas outlet 116. The in-line filter assembly can be used in certain locations where the right-angle filter assembly of the first embodiment may not fit within existing foreline geometries.

[0046] To form the exhaust chamber 138, the housing 112 includes a solid plate 136 that divides the interior space of the housing 112 between the filter chamber 118 and the exhaust chamber 130, and further includes an internal conduit 134 having a first open end 134a and a second open end 134b located above the level of the filtrate and extending through the plate 136 for discharge into the exhaust chamber 130. Although shown as terminating at the plate 136, it should be understood that the internal conduit 134 can extend through the plate into the exhaust chamber 138. Suitable conduits include tubes or pipes composed of inert materials such as aluminum, quartz, polymers, and commonly stainless steel alloys.

[0047] Similar to the previous embodiment, the housing 110 includes a feed tube 130 in fluid communication with the inlet 114 and extending into the liquid reservoir 120 to inject process gas into the filtered fluid in a manner similar to that described above.

[0048] Also similar to the previous embodiments, the liquid level in the liquid reservoir 120 may be maintained by a control system to ensure that the process gas is submerged in the filtrate, as described above.

[0049] Device 110 operates in a similar manner to device 10. Process gas flows into inlet 114 and is injected into filtered liquid in reservoir 120 through feed tube 130. Due to the perforations in feed tube 130, the process gas is bubbled into the filtered liquid, where solids or particulates are removed from the process gas as they are absorbed into the filtered liquid. The filtered gas is then discharged from filter chamber 118 through internal conduit 134, which directs the filtered gas to exhaust chamber 138, which then discharges the filtered gas through gas outlet 116.

[0050] In a manner similar to the previously described embodiments, filtered liquid can be circulated through the device 110 via a fluid circuit 128, which includes an inlet valve 128a (which is in fluid communication with the liquid inlet 122) and an outlet valve 128 (which is in fluid communication with the liquid inlet 124), as well as various conduits and pumps (e.g., a centrifugal pump or a magnetically coupled pump, not shown) to direct the filtered liquid into and out of the liquid reservoir 120 through the common port 126, in order to circulate the filtered liquid or simply replace the filtered liquid in the manner described above.

[0051] The device 110 may also include an optical window 140 for viewing the chamber 118. For example, the window or windows 40 may extend into and through the wall of the housing 12 and may be located below the desired level of filtered liquid so that the level and / or opacity or other characteristics of the liquid may be manually observed to provide manual control of the filtering device when desired.

[0052] As described above, in operation, as shown, a particle laden process gas stream enters the top of the apparatus 110 and passes through the internal feed tube 130, bubbles through the filter in the reservoir 120, and after filtering, enters the internal conduit 134, where it sheds its particles and exits the filtered liquid reservoir 120. The filtered gas then enters the exhaust plenum 138 and exits the apparatus 110 at the bottom and in line with the top process gas input.

[0053] Reference picture Figure 4 Reference numeral 210 generally designates another or third embodiment of a liquid filtration device that can be placed in a foreline of a semiconductor processing chamber exhaust and is configured to filter solids or particles from semiconductor process gases exhausted from the semiconductor processing chamber. Similar to the previous embodiment, the filtration device 210 includes a housing 212 having a process gas inlet 214 and a gas outlet 216. The process gas inlet 214 is configured to receive semiconductor process gas flowing from the semiconductor processing chamber, which is typically laden with solids or particles, and the gas outlet 216 is configured to discharge the process gas after the filtration process described above. Details of suitable materials for the housing structure are provided with reference to the first embodiment.

[0054] Figure 4 As best shown, the housing 212 also includes a filter chamber 218 that receives process gas via the process gas inlet 214 and discharges filtered gas from the filter chamber via the gas outlet 216. The filter chamber 218 forms a liquid reservoir 220 for holding a filter liquid that filters solids or particles from the process gas flowing into the filter device. For examples of suitable liquid properties and suitable liquids for filtering solids or particles from semiconductor process gas, reference is made to the first embodiment.

[0055] In the illustrated embodiment, the process gas inlet 214 and the gas outlet 216 are generally aligned, similar to the second embodiment. To this end, the housing 220 further includes an exhaust chamber 238 between the liquid reservoir 220 and the gas outlet 216 to allow the filtered gas to be exhausted from the interior of the filter chamber before being exhausted through the gas outlet 216. For further details of the exhaust chamber 238, reference is made to the previous embodiment.

[0056] Similar to the previous embodiments, the housing 210 includes a feed tube 230 that is in fluid communication with the inlet 214 but extends into the chamber 218 and optionally terminates above the filtered fluid. The tube 230 is also made of an inert material such as aluminum, quartz, polymer, and typically includes a stainless steel alloy.

[0057] In the illustrated embodiment, the tube 230 includes a restriction 230a to form a venturi tube and an inlet 222 for allowing filtered fluid to flow into the tube 230 and generating a pressure differential to draw process gas into the tube 230 through the inlet 214. The process gas mixes with the filtered liquid in the tube 230 and is then discharged into the filter chamber 218 through the tube 230. The filtered liquid is also discharged from the tube 230 into the liquid reservoir 220.

[0058] In a manner similar to that described above, filtered fluid may be circulated through the device 210 via a fluid circuit 228 (e.g., controlled by a controller, as described above, including a pump 228c (e.g., a centrifugal or magnetically coupled pump) in addition to valves 228a and 228b) which circulates the filtered fluid through the device 210 via various conduits 228d.

[0059] In the illustrated embodiment, as described above, the liquid inlet 222 is formed in the tube 230, while the liquid outlet 224 is located in the liquid reservoir below the liquid level.

[0060] Apparatus 210 operates similarly to apparatus 110. Process gas flows into inlet 214, but its flow is enhanced by the Venturi effect of the filtered liquid flowing through tube 230. The process gas mixes with the filtered liquid, is filtered, and is injected into filter chamber 118 through feed tube 230. The filtered gas is then exhausted from filter chamber 218 through internal conduit 234, which directs the filtered gas to exhaust chamber 238, which then exhausts the filtered gas through gas outlet 216.

[0061] In a manner similar to the previously described embodiments, filtered liquid can be circulated through the device 210 via the fluid circuit 228, which, as described, includes an inlet valve 228a (which is in fluid communication with the liquid inlet 222), an outlet valve 228b (which is in fluid communication with the liquid inlet 224), and various conduits to direct the flow of filtered liquid through the device 210. As described above, the fluid circuit 228 can also be configured to replace the filtered liquid after a given period of time or after the filtered liquid has reached a desired particle saturation level.

[0062] Similar to the second embodiment, the device 210 may further include an optical window 240 for the observation chamber 218 .

[0063] In either embodiment, the control system may include one or more sensors (not shown in all embodiments) that can be used to detect the level of the filtered liquid or measure the opacity (optical retardation) or other properties of the liquid that can be used to indicate that the liquid has reached a certain absorption level. Alternatively, two types of sensors may be used—one that measures the height of the liquid in the filter and another that measures a property of the liquid. In either or both cases, the control system can be used to adjust the flow of filtered fluid into and out of the device based on the one or more sensors to adapt to the output of the semiconductor chamber and / or optimize the filtration process. Alternatively, as described below, the filtered fluid flow can be automatically adjusted.

[0064] refer to Figure 5 , numeral 310 generally designates another or third embodiment of a liquid filtration apparatus that may be placed in a foreline between a semiconductor processing chamber and a process pump (see Figure 6 and Figure 7 ) and is configured to filter solids or particles from semiconductor process gases exhausted from a semiconductor processing chamber. Furthermore, as will be described more fully below, the liquid filtration device 310 is configured to communicate with a fluid circuit (328, described below) to allow for automated addition of fluid to and removal of filtered fluid from a chamber (318) of the fluid device.

[0065] Similar to the previous embodiments, the filter device 310 includes a housing 312 forming a filter chamber 318 having an inlet 314 for receiving semiconductor process gas flowing from a semiconductor processing chamber into the chamber 318 (see FIG. Figure 6 For example, filter device 310 is installed in the foreline of a processing system (between the semiconductor chamber and the process pump), typically carrying solids or particulates, and has a gas outlet 316 for discharging filtered process gas. Gas outlet 316 can be used to discharge the filtered gas from chamber 318 after the filtering process described below. Details of suitable materials for the housing structure are provided with reference to the first embodiment.

[0066] Figure 5 As best shown, chamber 318 forms a liquid reservoir 320 to hold a filtered liquid that filters solids or particulates from the process gas flowing into the filter device and then discharges them as waste. For examples of suitable liquid properties and suitable liquids that can filter solids or particulates from semiconductor process gases, refer to the first embodiment. In the illustrated embodiment, the process gas inlet 314 and gas outlet 316 are generally in line, having a right-angle arrangement, similar to the second embodiment. In addition, similar to the previous embodiment, the housing 310 includes a feed tube 330 that is in fluid communication with the inlet 314 and extends into the chamber 318 and terminates at or slightly below the (optional) filtered fluid in the liquid reservoir 320. The tube 330 is also formed of an inert material, such as aluminum, quartz, a polymer, and typically includes a stainless steel alloy.

[0067] In the illustrated embodiment, chamber 318 includes a rotating member 332, which is driven for rotation by a motor 334. Motor 334 is mounted externally or outside of housing 312, but its drive shaft 334a may extend through a sealed opening provided in housing wall 312a to engage rotating member 332. Alternatively, it may not penetrate the housing and instead be coupled to the rotating member via magnetic coupling, as described below. For example, the sealed opening may be formed by a sealing bushing or a sealing gasket. Rotating member 332 may be in the form of a plurality of blades mounted together to an annular support rotatably mounted at the bottom of housing wall 312a.

[0068] In one embodiment, the drive shaft 334a of the motor is coupled to the rotating member 332 via a magnetic coupling that penetrates the wall of the housing 312. For example, the shaft 334a can include a magnet, and the rotating member 332 can also include a magnet, for example, mounted within or adjacent to an annular support to provide the magnetic coupling.

[0069] As described above, rotating member 332 is located at the bottom of housing 312 within liquid reservoir 320 and, when rotated by motor 334, continuously stirs or rotates the filtered fluid (optional) within liquid reservoir 320. This fluid rotation causes particles of varying densities to thoroughly mix with the filtered fluid, which is then discharged from filter chamber 318 through outlet 312b formed in housing wall 312a. Furthermore, the rate of rotation affects the rate at which fluid is discharged from the chamber via outlet 312b and the rate at which filtered fluid flows into chamber 318 from the fluid circuit described below via inlet 312c (also formed in housing wall 312a). Furthermore, the rate of rotation determines the depth of vortex V generated by the fluid rotation.

[0070] In a similar manner as described above, filtered fluid may be selectively and automatically circulated through the device 310 via the fluid circuit 328 (eg, controlled by a controller, such as a programmable logic controller, including a microprocessor, as described below).

[0071] In the illustrated embodiment, fluid circuit 328 includes a conduit 340 in fluid communication with chamber 318 above the filtered fluid, a slide valve 342, and a plurality of control valves 328a (V1), 328b (V2), 328c (V3), 328d (V4), 328e (V5), and 328f (V6), which are opened and closed by a controller 350 (such as a microprocessor) to automatically control the flow of fluid through conduit 340 and through valves 342 based on the sequence of valve openings and closings described below. By providing fluid communication between chamber 318 (above the filtered fluid) and conduit 340, conduit 340 is subjected to the pressure in chamber 318. Due to the fluid communication between the foreline and chamber 318 via outlet 316, chamber 318 is under vacuum (or low or very low pressure). This vacuum (or low or very low pressure) is then extended to other parts of circuit 328, as described below. For example, conduit 340 can include stainless steel tubing.

[0072] Figure 5 As is well shown, the slide valve 342 comprises a cylinder 342a and a sliding piston 342b which moves up and down in the cylinder 342a under the control of a motor 343 (see FIG. Figure 5 ). Motor 343 is also controlled by controller 350 to open and close communication with chamber 318 and circuit 328 through valve 342.

[0073] Furthermore, circuit 328 includes two chambers 344 and 346, wherein chamber 344 is in selective fluid communication with a supply of make-up fluid via valve 328a (V1), and chamber 346 is in selective fluid communication with a supply of nitrogen via valve 328c (V3) and the valve comprising conduit 340. Thus, when valve 328 (V1) is opened, chamber 344 is filled with make-up fluid. Similarly, when valve 328E (V5) is opened, chamber 346 is filled with nitrogen. When valve 328E (V5) is closed and valve 328d (V4) is open, the pressure in chamber 346 is reduced to low, very low, or vacuum pressure.

[0074] To control the flow of fluid into and out of reservoir 320, cylinder 342a includes a first port (optionally formed by a conduit) in fluid communication with inlet 312c of housing 312 and a second port (optionally formed by a conduit) in fluid communication with outlet 312b of housing 312. Furthermore, piston 342b includes two transverse passages 342c and 342d that can be moved by motor 343 to align with the ports of cylinder 342a to allow fluid communication between reservoir 320 and chamber 344 and / or chamber 346, depending on the open or closed state of valve 328b (V2) and valve 328c (V3). Valve 328b (V2) provides selective fluid communication between chamber 344, spool valve 342, and reservoir 320, depending on the position of piston 342b. Valve 328c (V3) provides selective fluid communication between chamber 346, spool valve 342, and reservoir 320, depending on the position of piston 342b.

[0075] from Figure 5 It is easy to understand that when valve 328 (V1) is opened, the other valves (328b (V2), 328c (V3), 328d (V4), 328e (V5), and 328f (V6)) are closed (step 1, see Figure 5A ), the replenishing fluid is directed to chamber 344. When valve 328b (V2) and valve 328c (V3) are opened, and the remaining valves (328a (V1), 328d (V4), 328e (V5), and 328f (V6)) are closed (step 1, see Figure 5B ), and the motor 343 is driven to move the piston to a lower position (as shown in the figure) Figure 5 , wherein transverse passages 342c and 342d of piston 342b are aligned with ports of cylinder 342a), replenishing fluid is sent to reservoir 320 and particle filling fluid is expelled into chamber 346. When valves 328a (V1), 328b (V2), 328c (V3) and 328d (V4) are closed and valves 328f (V6) and 328e (V5) are opened (step 3, see FIG. Figure 5C ), fluid is removed from chamber 346 driven by a preset nitrogen flow through open valve 328e (V5). Once a given time has been allowed for fluid to be removed from chamber 346, valves 328a (V1), 328b (V2), 328c (V3), 328e (V5), and 328f (V6) are closed, and valve 328d (V4) is opened to allow chamber 346 to be evacuated so that the pressure in chamber 346 reaches equilibrium with the pressure in the foreline (see Figure 5DStep 4). This sequence of operations is repeated by the controller. The duration of the sequence of steps may vary, depending on the specific process and process settings. On average, the sequence can be expected to cycle every 10 to 20 seconds, depending on the particle load of the fluid. For semiconductor process effluents with low particle loads, the sequence may last 30 to 60 minutes.

[0076] Apparatus 310 operates similarly to apparatus 110, with process gas flowing into inlet 314 but then being enhanced by the vortex effect of the filtered liquid flowing around tube 330. The process gas mixes with the filtered liquid and is then filtered after being injected into filter chamber 318 through feed tube 330. The filtered gas is then exhausted from filter chamber 318 through gas outlet 316.

[0077] In the embodiment shown, the filtered liquid is thus dynamically circulated through the device 310 via the fluid circuit 328 .

[0078] The fluid circuit 328 may also be configured to replace the filtrate after a given period of time or after the filtrate has reached a desired level of particle saturation, as described above.

[0079] refer to Figure 6 and Figure 7 , the filter device 310 (or any other filter device 210, 110, or 10 described herein) can be installed in the foreline between the semiconductor processing chamber C and the process pump P, and further installed in a system having multiple chambers (C, C2, C3) and multiple pumps (P, P2, P3). The waste liquid from each filter device can be optionally directed to a common waste tank T, and can optionally have make-up fluid provided by a shared fluid supply tank T.

[0080] In either embodiment, the control system may include one or more sensors (not shown in all embodiments) that can be used to detect the level of the filtered liquid or measure the opacity (optical retardation) or other properties of the liquid that can be used to indicate that the liquid has reached a certain absorption level. Alternatively, two types of sensors may be used—one that measures the height of the liquid in the filter and another that measures a property of the liquid. In either or both cases, the control system can be used to adjust the flow of filtered fluid into and out of the device based on the one or more sensors to adapt to the output of the semiconductor chamber and / or optimize the filtration process.

[0081] Both right-angle and in-line filter device configurations can be passive ("passive" meaning the reservoir has a fixed amount of filter fluid that is periodically manually changed and replaced with fresh filter fluid), i.e., they are inserted in-line in a semiconductor processing system utilizing the process gas pressure and flow characteristics of the semiconductor processing system, or dynamic ("dynamic" meaning the particle-laden filter fluid is dynamically / automatically removed and exchanged with fresh filter fluid, as described above with reference to Figure 5 As noted, filtered liquid can be periodically removed and added based on scheduled maintenance periods via valves and optional pumps. As noted, in one configuration, a filtrate recirculation pump can be added to recirculate the filtrate, such as Figure 4 . In this embodiment, the recirculating filtrate can have a very high recirculation flow rate and can be mixed more effectively using the venturi shown and described. The use of the venturi can achieve a very high particle / gas separation and, as previously described, create a partial vacuum pull on the process gas entering the filter, thereby assisting the operation of the process vacuum pump and potentially reducing its overall energy consumption.

[0082] Directional terms such as "vertical," "horizontal," "top," "bottom," "upper," "lower," "inner," "inward," "outer," and "outward" are used to aid in describing the present invention based on the orientation of the embodiments shown in the figures. The use of directional terms should not be construed to limit the present invention to any particular orientation.

[0083] The above description is a description of the current embodiment of the present invention. Various changes and substitutions may be made without departing from the spirit and broader aspects of the present invention as defined in the appended claims, which are interpreted according to the principles of patent law, including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the present invention or as limiting the scope of the claims to the specific elements shown or described in conjunction with these embodiments. For example, but not limited to, any individual element of the described invention may be replaced by alternative elements that provide substantially similar functions or otherwise provide sufficient operation. This includes, for example, currently known alternative elements, such as those currently known to those skilled in the art, and alternative elements that may be developed in the future, such as those that may be developed by those skilled in the art when they develop, which are considered substitutes. In addition, the disclosed embodiments include multiple features that are described consistently and that can work together to provide a range of benefits. The present invention is not limited to those embodiments that include all of these features or provide all of the described benefits, unless the scope is otherwise clearly defined in the issued claims.

Claims

1. A liquid filtration device for gas / solid separation, the filtration device comprising: A housing having a filter chamber, a semiconductor process gas inlet, and a process gas outlet, wherein the filter chamber forms a liquid reservoir, and the semiconductor process gas inlet and the process gas outlet are in communication with the filter chamber, and the housing (112) includes a solid plate (136) that divides the interior space of the housing (112) between the filter chamber (118) and the exhaust chamber (138); a filtrate inlet and a filtrate outlet in communication with the liquid reservoir, for delivering the filtrate liquid to the liquid reservoir and removing the filtrate liquid from the liquid reservoir, respectively; a feed pipe, the feed pipe being in communication with the process gas inlet and extending into the liquid reservoir to directly inject the process gas flowing through the process gas inlet into the filtered liquid in the liquid reservoir; as well as An internal conduit (134) is fluidly connected to the filter chamber and the exhaust chamber to direct the filtered process gas flow from the filter chamber to the exhaust chamber, the internal conduit (134) including a first open end (134a) located above the level of the filtered liquid and a second open end (134b) extending through the solid plate (136) to discharge into the exhaust chamber (138).

2. The liquid filtering device according to claim 1, wherein: The semiconductor process gas inlet is in a straight line with the process gas outlet.

3. The liquid filtering device according to claim 1, wherein: The exhaust chamber is located between the liquid reservoir and the process gas outlet.

4. The liquid filtering device according to claim 1, wherein: The feed tube comprises a perforated feed tube.

5. The liquid filtering device according to claim 4, wherein: The perforated feed tube includes a distal portion and a plurality of perforations at the distal portion.

6. The liquid filtering device according to claim 5, further comprising a filtered liquid control system for controlling the flow of filtered liquid into and out of the liquid reservoir.

7. The liquid filtering device according to claim 6, wherein: The filtered liquid control system includes a controller and a fluid circuit. The controller controls the fluid circuit to adjust the flow rate of filtered liquid into and out of the liquid reservoir and is configured to maintain the liquid level of filtered liquid in the liquid reservoir.

8. The liquid filtering device according to claim 1, wherein: The feed tube has a venturi restriction therein and a venturi inlet in fluid communication with the semiconductor process gas inlet or the liquid filter inlet for drawing process gas or filtered liquid into the feed tube.

9. The liquid filtering device according to claim 8, further comprising a filtered liquid control system for controlling the flow of filtered liquid into and out of the liquid reservoir, the filtered liquid control system comprising a controller and a fluid circuit, the controller controlling the fluid circuit to regulate the flow of filtered liquid into and out of the liquid reservoir and being configured to maintain the filtered liquid at a liquid level in the liquid reservoir.

10. The liquid filtering device according to claim 9, wherein: The filtered liquid control system includes a pump in fluid communication with the filtered liquid inlet to pump filtered liquid into the liquid reservoir. 11 . The liquid filtering device according to claim 10 , wherein the filtered liquid inlet is in fluid communication with the liquid reservoir through the feed pipe, wherein the pump is configured to circulate the filtered liquid into the liquid reservoir through the feed pipe.

12. The liquid filtration device according to any one of claims 1 to 11, wherein: The housing includes one or more optical windows for viewing the filtration chamber.

13. The liquid filtration device according to any one of claims 1 to 11, wherein: The filter chamber includes a rotating member to rotate the fluid in the filter chamber.

14. The liquid filtration device according to any one of claims 1 to 11, wherein: The filtration chamber is in selective communication with a fluid circuit configured to control the flow of filtered liquid into and out of the filtration chamber, and optionally includes a controller to provide for automatic addition and / or removal of filtered liquid from the filtration chamber.

15. A method for separating solids from semiconductor process gas using the liquid filtration apparatus according to any one of claims 1 to 14, the method comprising the steps of: directing the semiconductor process gas into a stream of filtered liquid or a reservoir containing the filtered liquid, thereby filtering the process gas; as well as Discharge filtered process gas.

16. The method of claim 15, wherein directing comprises bubbling a semiconductor process gas into a filtered liquid in a reservoir.

17. The method of claim 16, further comprising circulating the filtered liquid through the reservoir to remove spent filtered liquid.

18. The method of claim 15, further comprising forming the filtered liquid into a vortex or a venturi flow, and directing comprises drawing the semiconductor process gas into the vortex or the venturi flow.

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