TW442317B - High flow metal membrane gas filter - Google Patents

Abstract

An ultra-high efficiency, highly porous particulate gas filter capable of operating at gas flows from about 300 slpm to about 25,000 slpm is formed of a highly porous, compact filter sintered metal media. The filters according the present invention exhibit a filtration efficiency substantially in excess of a 6 log reduction (99.9999+)(6LRV) and preferably better than a 9 log reduction (99.9999999+)(9LRV) at the desired gas flow rates with a flow per unit area of from about 1 to about 4 slpm/sq.cm. These filters are compact, providing a unit which is significantly smaller than those conventionally used in the filtration of ultrahigh process gas streams with the same or greater efficiency of filtration and flow/unit area.

Description

4423 1 7 —__ 5. Description of the invention (1) The present invention relates to a gas filter device based on a metal thin film for high flow applications. More specifically, the present invention relates to a gas filter device based on a metal thin film, which is used for high flow applications and has a small volume. BACKGROUND OF THE INVENTION Semiconductor manufacturing is limited by purity. A key point in the chemical vapor deposition of various components used in the manufacture of semiconductors is that no particulate impurities should be present. A tiny particle can destroy an entire Shi Xi wafer, thus causing a loss of profit on its final product. To this end, a complete industry has been developed. This industry is concerned with filtering gases that may come into contact with semiconductor products during the formation of semiconductor products. The entire delivery system is carefully designed to minimize contamination from the gas supply. These gases include silicon fired, arsenic, hydrochloric acid, and phosphine. The components used in the system are designed to reduce particle shedding, outgassing, and other pollution caused by the components themselves. Particle filter is an important component of the system. Β This filter device can ensure that particles cannot reach the workpiece. Generally, such a filtering device is not installed until the gas component is delivered to the workpiece, so it is called a "point of use" C po i n t 0 f υ se) filtering device. Such a filtering device must be highly efficient and small in size. It is basically made of organic thin films, thin ceramic thin layers, or sintered metal fibers (or fine particles). And U.S. Patent No. 5,487,771. This “point-of-use” filter device can remove almost all particulate pollutants, and the rating is based on its log reduction value (LRV). The log reduction value should be at least 6, which is an acceptable range, preferably at least 9 (efficiency is gg. G999

Page 5 4423 1 7 V. Description of the invention (2) to 99.9999999). This kind of filtering device can reach the above-mentioned value at the minimum flow rate. The so-called minimum flow rate is basically about 75 SLPM at a standard liter / minute (SLPM). There are also filtering devices used before the "point of use". Basically, such filters are used in high-flow applications in distribution systems. The flow range here is 150 to 25,000 SLPM. Due to the large flow rate, this type of filtering device is basically very different from a “point of use” filtering device. Generally, such a filtering device is an extremely long tube made of sintered metal particles. For example, there is such a crack that has a length of 36 inches (91.44 cm) and an outer diameter of about 2 to 4 inches (5 to 10.1 cm). The membrane of this filter device is basically strong. Porosity is basically low. This filtering device can also be replaced by a series of (basically 3) tubes that overlap each other so as to provide the same length in a shorter length (9 to 12 inches', that is, 22.86 to 30.48 cm). Filter, area. This type of film must have the above-mentioned robustness and length because it must withstand high flow rates. An example of a disc design as described in U.S. Patent No. 5,11,4,4,7 is similar to a "point of use" filter device. According to the patent, the flow rate applicable to this design can reach 1,400 SLPM. The unit is approximately 2 feet (60 cm) long and 4 to 5 inches (10 to 12.5 cm) in diameter. Although the patent does not indicate that the filter device can be used for higher flow rates according to the design, the following inference can be made according to the description of the patent: The filter device used for higher flow rates may have a larger volume and the The amount of filter material is also significantly larger, so as to achieve low pressure values and the required filtration efficiency. What is currently needed is a high-flow metal film gas filter device ’, which has a small volume, ranging from 150 to

442317 V. Description of the invention (3) The logarithm reduction value of the particles provided under the gas flow rate of 25.0 0 0 SLPM is at least 6, preferably 9. This is the device provided by the present invention. SUMMARY OF THE INVENTION The present invention includes a high porosity, high flow filtration device. The metal film has a porosity of at least 35 percent, preferably 55 to 80 percent. The volume of the filter device is small, similar to several "use-point" filter devices; its logarithmic reduction is at least 6; and it can operate at a gas flow rate of up to 25,000 SLPM. Brief Description of the Drawings Fig. 1 is a sectional view of a first specific example of the present invention. Fig. 2 is a sectional view of a second specific example of the present invention. FIG. 3 is a top sectional view of a manifold of the specific example shown in FIG. 2. Fig. 4 is a top cross-sectional view of a second design of the manifold of the embodiment shown in Fig. 2; Fig. 5 is a sectional view of a third embodiment of the present invention. Detailed description of the present invention The present invention provides a high-efficiency, small-sized, high-porosity metal thin-film filter device that can be used at high gas flow rates. The filter device is a high-flow filter device that is extremely suitable for gas applications, such as semiconductors, fiber optics, and other related industries where space is very valuable. FIG. 1 is a specific example of the present invention. The filter unit includes a casing 1 having an inlet 2, an outlet 3, and a casing 4 located between the inlet 2 and the outlet 3. As shown in Fig. 1, the inlet 2 is installed at one end 5 and the outlet 3 is installed at one end 6 opposite to the end 5. This is one of the typical "in-line" devices

442 3 1 7 V. Description of Invention (4) Practice. It is also possible to change the inlet and outlet at the same end of the housing. This is for modular design and non-in-line or rectangular structures (not shown). The casing 4 contains a filtering device 7 formed of sintered metal with pores. In this specific example, the filtering device 7 is composed of a series of sintered porous metal discs welded to each other. The disc 8A closest to the entrance 2 has a complete continuous surface. The other discs 8B have a central hole 9 through which the filtered fluid can pass and reach the outlet 3 directly. The manner in which the filter device 7 is fixed in the housing can form a fluid-tight seal between it and the housing 1 or the inlet 2 or outlet 3. The manner in which it is sealed is not critical to the invention. In this specific example, this seal is formed at the opposite end 6 of the casing 1, and the method is to weld the last disc 8B in the series of discs to an ear 10 on the inner surface of the casing 1. In addition, in this specific example, a spring-force metal ring 11 is installed near one end of the filter device near the inlet 2. The ring 1 1 is used to install and position the series of discs in the casing to facilitate the flow of fluid between the filtering device 7 and the casing 1 so as to ensure that all discs participate in the filtration of the fluid. Alternatively, the outlet may include a rod 12 (not shown), which may be fixed to the filtering device 7 by welding, screwing, or other similarly known methods. In another specific example, the size of the lowermost disc may correspond to the internal dimensions of the shell, and the disc may be sealed to the shell by means of welding, spring retainer, metal adhesive, etc. *. Fig. 2 shows a second specific example of the present invention. In this specific example, the filtering device 20 is constituted by a series of pipes 21 mounted on a manifold 22. The manifold can be mounted on the inner surface of the casing 23 to form a fluid seal between the casing 23 and the manifold 22

442317 V. Description of the invention (5) (as shown in this specific example); or installed on a rod 2 4 (not shown) attached to the outlet 2 5 so that one end, the rod 24 and the manifold 2 2 The connection can form a fluid-tight seal between the filter device element 2 1 and the outlet 25 with the outlet 25 on the other end = no matter which one is used, the gas enters the housing 23 from the inlet 26, passes through the thorium device 20, and then The outlet 25 is discharged. It can also be seen in the drawing that these piping systems are composed of a column-shaped flexible material and have-the end 26 (away from one end of the manifold) 'and sealed by an end cap 27, which can be fixed in various ways. 'For example, by welding or becoming part of the sintering process ... etc. Another method (also known in the art): the end cap made of porous sintered metal can be part of the tube during the sintering process. This specific example has a series of 5 tubes in the figure, which are arranged around the manifold in a concentric manner. You can use more than 5 and less than 5 pipes as required to achieve the required flow conditions and filtering. ^ ^ The only restriction is that a manifold of any size can be installed: in the second? Arrange in a staggered manner so that nd surrounds the manifold ^ ^ ^ rs iu m more equipment &. For example, Figure 3 is a top view of the disagreement in Figure 2. Fig. 4. Top view of piI χ λ ,, sl.,. R and its M 栌 妯 π display arrangement, where B 3 丨. Depending on the situation, a series of tubes can be welded to form a longer answer and the αβ mineral power can be connected into a tube. The length of the tube should be able to match the number of tubes and: two changes: one to a longer length of transition characteristics. Basic 1 officer; vv to achieve the required flow conditions and minutes), preferably about 3 inches Γ7 ”Ya \, Chuan · 54 to 25.4 cm, τ (7.62 cm) to 7 central p inches, if about Inch ⑴.6 to 15.24 cm) mesh, 丨 scoring for 4 to 6 clips, the United States can be π knife) shell 1 is better. The diameter of the official can vary greatly and owes about 0.25 to 3 inches (Outer diameter) (0635 to 7.62 male

Page 9 3 1 7____ Five 'Description of the Invention ~ ^ ---------- The thickness of the tube wall is from about 0, 0 62 5 to 0_ 3 7 5 Ying 忖 (.159 to 〇 52 52 5? for). The thickness of the pipe wall can be changed according to the applicable flow conditions of the pipe. The pressure drop and the porosity of the filter material can be changed according to the needs or allowable values. Shows another-specific example of the present invention, which is basically the one shown in Figure i, which is a correction, and it includes fewer discs, so it is particularly suitable for lower flows in the high flow range, which is 15. To 3,000 SLpM. Since there are fewer components, the loop shown in Fig. 1 is not necessary 'but can also be used when needed. Although the specific example shown in the figure is a threaded joint, other joints known to those skilled in the art can also be used, including (but not limited to) O-rings, compression seals, or those known in the industry as counter-type welded pipes. Simple unthreaded end. The present invention selects an appropriate number of components (the number of discs or tubes) according to the required type, and selects an appropriate flow value and pressure drop. ^ The present invention can be inserted into a gas flow to allow gas to flow through the device to remove Particles in the gas stream. The filter device element (whether in the form of a disk or a tube) of the present invention is preferably composed of a substantially homogeneous porous sintered metal material. The material may be a very fine particulate metal, or preferably a dendritic metal powder (see U.S. Patent No. 5,487, Ή1). The metal chosen may include stainless steel (such as Grade 316), nickel (such as Inco 255 powder), nickel alloys (such as Has1; elloy C- 2 2), complexes, chromium alloys or mixtures, titanium, palladium, or other similar Of metal.

Page 10 442 3 彳 7 i., Note (7) The method used to manufacture the filter element is a method well known in the art. For example, it can be found in US Patent No. 5,1 14, 557 and the United States Patent Nos. 5, 4 8 7, 7 7 1 'The two patents are incorporated herein in their entirety by reference. Basically, the filter element can be used in the dry or wet state during molding, and the same applies to the use of adhesives. It is preferable to use dry worries 'during molding without using an adhesive, and use the air-laying technique as described in U.S. Patent No. 5' 4 8 7, 7 71. The shape of the filter element is basically made into a desired shape by pressing, and it can be installed in a mold when it is sintered in a compressed form. 'If the shape is stable, the mold may not be used. Passed components are basically sintered in hydrogen gas, and the temperature and time for sintering are sufficient to provide shape-stable components. The degree of sintering is preferably minimized, as this will result in a high porosity structure that will help increase flow and filtration efficiency. The basic sintering temperature of nickel is about 500 to 1,000 degrees Celsius, preferably about 650 to 750 degrees Celsius. Non-scale steels, nickel alloys, chromium, and titanium have higher sintering temperatures, which range from about 900 to 1,400 degrees Celsius. The sintering time varies depending on the temperature, and the porosity and strength required for sintering the finished product. Basically, the sintering time is about 3 to 20 minutes. In terms of recording, the sintering time at about 50 to 75 degrees Celsius is preferably about 5 to 10 minutes. The measurement of filtration efficiency is based on the "characteristics of ultra-high efficiency membrane filtration devices for gas applications" (Rubo et al., "Environmental Science Periodical", Vol. 31, Nos. 26-30 P. 19 May 1988) This article explains the method. In this test, the 'passing device is tested under one or more test conditions' and under these conditions' is applicable to the filter device

Page 11 442317 V. Description of the invention (8) Testing of the most penetrable particle size For the purposes of the present invention, 'the filter efficiency must be at least a log reduction of six when tested at the most penetrating particle size. . Tested at the most penetrating particle size; the efficiency must be at least a log reduction of 9 at least. Another value used to determine the efficiency of a pass-through device is (flow rate) / (unit filtration area) when a log reduction is reached. By way of example, f 'according to one of the transition devices of the present invention has a filtering area of 14 square centimeters. The device achieves a log reduction of 9 at a flow rate of 300 SLPM. Therefore, its (flow rate) / (unit area) ratio is 2 . 1 SLPM / cm2. When the same filter is installed, the logarithmic reduction value of 6 can be achieved when the flow is 7 50 SLPM. Therefore, the ratio of (flow) / (unit area) is 5.3 SLPM / cm2. (Flow) / (Unit area) This ratio is preferably the measured value when the logarithmic reduction value reaches 9. As far as the filtering device of the present invention is concerned, when the ratio is 9, it should be from 4 to 4 cm / cm2. As far as the tenth of the present invention is concerned: the device ^ The ratio is preferably 15 to / 乩 ⑽ / 平 Π when the logarithmic reduction value is nine. = This table shows the required flow rate and required porosity of the product. ; Γ should be reached between-equilibrium state. The scope is limited. " Acts of Confession "and not by any means to the present invention Example 1: Here has been made according to the description of the present invention as shown in Fig. 1. Outside broken ^ X Λ A dagger filter module, its structure _ 2 /, all peripherals are made of non-scale steel (3 16L), length 8 忖, diameter 2.5 inches (measurement position is clothing length 8. Μ There are 17-inch central holes in the center, one series, with inlet and outlet with a total of 35 pieces of sintered metal thin film circle j

Page 12 »442 3 1 7 V. Description of the invention (9) '---

They are welded together, and the discs closest to the exits form a fluid seal. "# '+ U These discs are made of a nickel film with a diameter of about 2 inches (5 cm) and a thickness of 0.060 inches. Inches (〇 · 1 524 cm). These films are made by Mil lipore Corporation according to the description of U.S. Patent No. 5,487,771. The sintering temperature is 825 ° C and the sintering time is 90 minutes. The porosity of these films is about 3δ to 42%. Air flows through the unit at a flow rate of 1500 SLPM at inlet pressures of 30, 50, and 70 crushes per square inch. The pressure drops of the device corresponding to the inlet pressures listed above were measured to be 5.0, 5.0, and 3.5 pounds per square inch, respectively. When testing with the device's most penetrable particle size (0.1 micron), the particle filtration efficiency measured at each inlet pressure above is greater than the log reduction value9. Example 2: An apparatus according to the present invention has been made here and includes stacked disks arranged in a manner similar to that shown in FIG. 5. These discs are nickel filter element beta films made according to U.S. Patent No. 5, 48 7, 771 having a porosity of approximately 38% to 42% and a diameter of approximately 2 inches (5 cm). 0.060 inches (0.124 cm). Air at 30, 60, and 70 pounds per square inch of inlet pressure 'flows through the device at a flow rate of 300 SLPM, with corresponding pressure drops of 5.5, 3, 5, and 3.0 pounds. When testing with the most penetrating particle size (0.1 micron) of this device, the particle filtration efficiency measured at each inlet pressure listed above is greater than the logarithmic value9.

Page 13 :: 4423 17 ______ V. Description of the invention (10) Example 3: Here has been made according to the design of FIG. 2 to make a sintered branch tube of a seismically installed branch system according to one of the present invention. U.S. Patent No. 87,771 is made of $. One end of it has a solid recording medium end, and the top of the eunuch's is one of the closed tubes @. The tubes are * inches (5.8 cm) in length, with an outer diameter of 0 635 inches (1 61 cm), and the tube is a central blade (0.16510). The porosity is approximately ⑻ percent. Thin film she = 21.8 square inches (14 square centimeters). These pipes are ~, =, the turntable is connected to the outside in a fluid-tight manner,-the overall dimensions of the device are P. Inches. * 5 inches in length (including fittings), outer diameter 2.4 Air flows through the device at inlet pressures of 30, 60, and 90 pounds per square inch, with flow rates ranging from 0 to 50 0 SLPM 'The pressure drop at 500sLp widely obtained was 7 8, 4 · 2, and 3 · 7 per square inch. The most penetrable particle size of the device (01 micron) was measured at 300 SLPM. The particle transition efficiency is greater than the log reduction of 9 and at 5 at SLPM it is greater than the log reduction of 6.

Claims (1)

442 3 1 7 Six 'scope of patent application. A filter device containing a porous metal film for high flow gas applications' The filter device includes a metal shell having a shell for containing a porous metal film; The casing has an inlet and an outlet; a porous metal film is located in the casing, between the inlet and the outlet, and the metal film is connected to the casing, or the inlet, or the outlet in a sealable manner to constitute a The filtering flow path through the casing; the porosity of the metal film is about 35 to 70 percent; the filtering device is the most permeate when the flow rate is about 150 to 25,000 SLPM The particle size reduction provided by the permeable particle size is at least 6. 2. For the filtering device of the scope of patent application, the metal film is a sintered thin film. The particles constituting the sintered film can only be selected from the following: dendritic particles, fiber particles, and a mixture of the two. ; And wherein the metal can only be selected from the following: stainless steel, nickel, nickel alloy, chromium, chromium alloy, chromium mixture, titanium, palladium, and mixtures of the above items. 3. For the filtering device in the first scope of the patent application, the logarithmic reduction value of particulate filtration is at least a log reduction value of 9. 4. The filtering device according to item 丨 of the patent application scope, wherein the inlet is formed on the casing at the opposite end to the outlet. ”/ 5. The filtering device according to item 1 of the scope of patent application, wherein the film is a series of passing members, and the stack is $ &# $ m 4 I y, gap > ft #, the way in the product filtering device Can provide a hole: surface area ③ surface area is at least about 5 4 tones of the volume occupied by the filter element. 6. If the scope of patent application of the first alfalfa series-end seal: consider the device 'where the film is composed of ^' Isopipes are connected via a manifold Page 15 f. 442 3 1 7 __7. The scope of patent application is in the outlet; and wherein the manifold is installed in the casing so as to be adjacent to one side of the inlet and formed between the manifold and the casing Fluid-tight. 7. For the filtering device of the scope of patent application, the metal constituting the casing can only be selected from the following: stainless steel, nickel, chromium, nickel alloy, and chromium alloy. 8. For the filtering device of the scope of application for patent No. 5, the series of filtering members are arranged as pairs of disks welded to each other, the disk closest to the entrance is continuous, and the remaining disks have a central hole. Connectable to the outlet, the discs are attached to the housing via a first metal fixing ear and a second fixing ear, thereby forming a fluid seal between the housing and the discs, the first The metal fixing ear is mounted on a portion of the housing adjacent to the entrance, and the second fixing ear is mounted on a portion of the housing adjacent to the exit. 9. The filtering device according to item 8 of the scope of patent application, wherein the first fixing ear is a spring force ring having one or more outwardly protruding arms and abutting against the housing; the second fixing ear is A ring has a central opening, and the ring is welded to the shell by its outer circumference. 10 · The filtering device according to item 9 of the scope of patent application, wherein the second fixing ear is a ring, and the ring is also fused to the last piece of filter element disk. 1 1. According to the patent application scope item 1, the inlet and outlet are located on the same side of the housing. 1 2. The filtering device according to item 1 of the patent application scope, wherein the inlet and the outlet are located on the same side of the housing and adjacent to each other. 1 3. —A porous metal membrane filter device including a casing, the casing Page 16 L4423J7__ VI. The scope of patent application has an entrance and an exit, and a shell located between the entrance and the exit; a porous sintered metal film is located between the entrance and the exit, and the fixing method can be in the film A fluid seal is formed with the outlet so that all fluids entering the inlet must pass through the membrane before reaching the outlet; and where the filter device has a flow rate of about 150 to 2 5, 0 0 0 SLPM Provides a particle filter log reduction of at least 6. 1 4. The filtering device according to item 1 of the scope of patent application, wherein when the logarithmic reduction value is 9, the unit area flow is about 1 to 4 SLPM per square centimeter. 1 5. The filtering device according to item 1 of the scope of patent application, wherein when the logarithmic reduction value is 9, the unit area flow is about 1.5 to 3 SLPM per square centimeter. 16. The filtering device according to item 13 of the scope of patent application, wherein when the logarithmic reduction value is 9, the unit area flow is about 1 to 4 SLPM per square centimeter. 1 7. The filtering device according to item 13 of the scope of patent application, wherein when the logarithmic reduction value is 9, the unit area flow rate is about 1.5 to 3 SLPM. Page 17