WO2009038326A2

WO2009038326A2 - Scrubber using mesh filter and apparatus for exhaust gas treatment in semiconductor fabrication equipments using the same

Info

Publication number: WO2009038326A2
Application number: PCT/KR2008/005466
Authority: WO
Inventors: Chulsoo Byun; Mancheol Han
Original assignee: Piezonics Co. Ltd.; Korea Institute Of Industrial Technology
Priority date: 2007-09-21
Filing date: 2008-09-17
Publication date: 2009-03-26
Also published as: WO2009038326A3; WO2009038326A4

Abstract

The field of the present invention relates to a scrubber using mesh filter and an exhaust gas treatment system using the scrubber, which makes it possible to collect powders on-time with little need for maintenances or repairs of the scrubber. More particularly, in the field of semiconductor fabrication industries the main process such as deposition or etching is rarely interrupted for the maintenance of the scrubber, hence the productivity is enhanced and the environment is saved. The present invention comprises : a process chamber to perform a fabrication process of the semiconductor devices; a process vacuum pump to inhale the exhaust gas from the process chamber; a housing provided with an inlet port and outlet port for an exhaust gas; a mesh filter which is placed between the inlet and outlet port of the housing, which passes the exhaust gas through, and which captures powders contained the exhaust gas at a capturing surface thereof; a powder detaching means to detach powders from the capturing surface of the mesh filter; a discharge port which is provided at a side of the housing and connected to a vacuum suction means to release the powders detached from the housing; a by-pass line which connects the process chamber directly to the process vacuum pump; and on/off valves controlling the flow of the exhaust gas from the process chamber to either the scrubber or the process vacuum pump.

Description

Description SCRUBBER USING MESH FILTER AND APPARATUS

FOR EXHAUST GAS TREATMENT IN SEMICONDUCTOR FABRICATION EQUIPMENTS USING THE

SAME Technical Field

[1] The field of the present invention relates in general to a scrubber using mesh filter and an exhaust gas treatment system using the scrubber, which makes it possible to collect powders on-time with little need for maintenances or repairs of the scrubber. More particularly, by applying skills of the present invention to the field of semiconductor fabrication industries, the main process such as deposition or etching is rarely interrupted for the maintenance of the scrubber, hence the productivity is enhanced and the environment is saved. Background Art

[2] The semiconductor equipments using gasses for the process such as deposition or etching release exhaust gasses inevitably. Since the exhaust gas would contain hazard materials and/or powders which exert fatal effects to health and environments, discharging the exhaust gas without proper treatments is severely prohibited by the law.

[3] The equipment for treating hazard gasses or powders is called a scrubber and classified into wet and dry types. Wet type scrubbers effectively purify the hazard gas or powder, but the configuration is rather complicated and is accompanied by troublesome maintenance works such as treatments of the waste water, which may invoke the second contamination problem. Dry type scrubbers have rather simple configurations, but may have a disadvantage of less performance. In this regards the dry type scrubber is usually installed before the wet type scrubber to lessen the burden imposed on the wet type scrubber.

[4] The exhaust gas, even if it is not a stream of powders itself, may contain very fine particles and/or is easily transformed into powders as a result of a slight physical or chemical change. There are three well known methods to capture powders from the exhaust gas.

[5] Firstly, electrostatic collection method can be adopted. That is, fine particles contained in the exhaust gas are charged by electrons emitted from wire type cathodes, then captured by capturing anode plates. During this process the fine particles could be agglomerated into large sized ones. [6] Secondly, some kinds of gasses are phase transformed into solids under reduced temperature. In an LPCVD process which grows silicon nitrides on silicon substrates by chemical reactions of gasses including ammonia(NH \ ammonium chloride(NH

3 4

Cl)is produced and exhausted as a by-product gas. The ammonium chloride can be captured as powders on the surface of a cold trap using liquid nitrogen or a coolant of very low temperature.

[7] Thirdly, re-burning of the exhaust gas could produce relatively large sized particles.

As a typical example, silane(SiH ) gas which did not participate in the film growing

4 process in the process chamber can produce silicon di-oxide(SiO ) particles after ex-

2 periencing re-burning with oxygen at the exhaust line.

[8] The powders produced by methods described above are accumulated at the bottom of the scrubber, or captured at the surface of a fibre form mesh filter made from textures or steel wires provided at the exit part of the scrubber. In this regards the scrubber capturing powders inevitably needed a periodic maintenance or a repair work to clean the inner surface of the scrubber or to exchange the mesh filter. The maintenance work, however, would be done in an undesirable condition releasing unwanted powders to the atmosphere during the work and even would require the interrupt of the main process such as etching or deposition.

[9] With regard to the exchanging period of the mesh filter, Fig. 1 shows an apparatus described in Korean Patent No. 0239791 which suggests a way of increasing the surface area of the mesh filter by forming a multiple folded shape. But there remains an unavoidable problem of eventual exchange of the filter to prevent the clogging which affects the main process by invoking the increase of the back pressure. Disclosure of Invention Technical Problem

[10] It is an object of the present invention to solve the problems described above, where powders are positively generated from the exhaust gas, captured by a scrubber equipped with a mesh filter, and finally collected with little need to exchange the mesh filter or to repair the scrubber, therefore supplying a solution for a scrubber with a mesh filter suitable for obtaining economical benefits and saving long term environments.

[11] It is another object of the present invention to provide an exhaust gas treatment system in the semiconductor fabrication industry, where the sweeping of the mesh filter is done during the interval time for substrate exchanging in the main process such as etching or deposition, therefore keeping the continuous performance of the mesh filter with little need of additional maintenance of the mesh filter. Technical Solution

[12] One aspect of the present invention provides a housing with an inlet and outlet for the flow of the exhaust gas.

[13] Another aspect of the present invention provides a mesh filter which passes the exhaust gas through and captures powders at the capturing surface, which has a cylindrical shape, of which vertical side is a mesh of a fibre form made from textures or steel wires, and of which vertical outer surface is the powder capturing surface.

[14] Another aspect of the present invention provides a powder detaching means to detach the powders from the capturing surface of the mesh filter, wherein a sweeping gas injected from a nozzle detaches the powder captured at the outer surface of the said mesh and is forced to flow into a vacuum suction means, thereby discharging the powder mixed with the sweeping gas from the said housing via a discharge port provided at the bottom of the housing. And a nozzle driving device covers the whole inner surface of the vertical mesh by the trace of the nozzle.

[15] The mesh filter has an another aspect, wherein the shape of the mesh filter is a cylinder and an outlet tube penetrates the center of the roof of the housing through a first rotation supporting components to allow a rotating motion of the mesh filter around the outlet tube while keeping sealing of the housing. A non-rotating ambiance supply port connected to the rotating outlet tube is branched into two ways, one way of the branch to discharge the exhaust gas and the other way of the branch to allow the inflow of a sweeping gas such as air.

[16] And the powder detaching means has another aspect, wherein a vertical suction beak is provided near to the outer surface of the vertical mesh which is rotated around the outlet tube and connected to the vacuum suction means, thereby the powder is detached from the mesh by a co-operation of the vacuum suction exerted to the suction beak and the inflow of the sweeping gas supplied to the inner surface of the vertical mesh via the said ambiance supply port during the time the mesh filter is rotated.

[17] Another aspect of the present invention provides an exhaust gas treatment system which comprises a process chamber to perform a fabrication process of the semiconductor devices, a vacuum pump to inhale the exhaust gas from the process chamber, a scrubber with a mesh filter installed between the process chamber and the vacuum pump, a by-pass line which connects the process chamber directly to the vacuum pump, and on/off valves controlling the flow of the exhaust gas from the process chamber to either the scrubber or the vacuum pump.

[18] The above vacuum suction means could be further combined with a powder collecting means, wherein the powder is detached from a second mesh filter due to centrifugal force and accumulated at the bottom of a second housing. Finally the powder is discharged from the second housing by an operation of a discharge valve and collected to a collection bag.

[19] Another aspect of the present invention provides a powder generation means to generate powders positively from the exhaust gas, wherein a plurality of bar or U shaped cartridge heaters are included. The cartridge heater induces reactions of the exhaust gas to deposit powders on the surface thereof. A funnel shaped hopper is provided to constitute the lower part of the powder generation means, where a discharge port is provided at the bottom of the funnel shaped hopper and is connected to the scrubber equipped with a mesh filter.

Advantageous Effects

[20] Therefore, without disassembling the scrubber the sweeping of the inner space of the scrubber is done. The performance of the mesh filter remains good for a long time and the environment could be little affected by the process for collecting the powder.

[21] Moreover, in the semiconductor fabrication process using the scrubber of the present invention, the sweeping of the mesh filter, that is, the detaching of powders from the mesh filter could be done for a very short interval time when the finished substrate comes out of the process chamber and a new substrate is supplied into the process chamber followed by normal main process like deposition or etching. Therefore, the productivity is enhanced. Brief Description of the Drawings

[22] Fig. 1 is a perspective view of a conventional mesh filter whose surface area is expanded;

[23] Fig. 2 is a vertical cross-sectional view of a first embodiment of a scrubber which shows the configuration to detach the powder captured at the outer surface of a mesh filter by using a sweeping gas;

[24] Fig. 3 is a horizontal cross-sectional view of the first embodiment of the scrubber;

[25] Fig. 4 shows a second embodiment of a scrubber where a suction beak is used to detach the powder; [26] Fig. 5 is a perspective view of the suction beak;

[27] Fig. 6 shows a powder collecting means to collect the powder from the scrubber;

[28] Fig. 7 is a schematic view of an exhaust gas treatment system that may be used in conjunction with an exemplary embodiment of the present invention; and

[29] Fig. 8 is another schematic view of an exhaust gas treatment system with a powder generation means that may be used in conjunction with an exemplary embodiment of the present invention. Best Mode for Carrying Out the Invention

[30] Following descriptions with attached drawings are given to enable any person skilled in the art to realize the present invention. Fig. 2 and Fig. 3 are respectively vertical and horizontal cross-sectional views of a first embodiment of the present invention. A scrubber 100 comprises a housing 110, wherein internal sealing of the housing is kept, the upper part of the housing has a cylindrical shape 110a and the lower part thereof has a funnel shape 110b, an inlet port 111 is provided at the side wall of the housing for the inflow of the exhaust gas which is released from a process chamber at previous stage and may contain powders, and an outlet port 112 is provided at the roof of the housing to release the exhaust gas deprived of powders.

[31] A the inside of the housing 110 a mesh filter 120 is provided between the inlet port

111 and the outlet port 112. The exhaust gas supplied via the inlet port 111 passes through the mesh filter 120 and flows into the outlet port 112. The mesh filter 120 has a cylindrical shape, the upper part thereof constitutes a part of the roof 105 of the housing, the vertical side thereof is a mesh of a fibre form made from textures or steel wires, the outer surface of the mesh is the surface for capturing the powder P. To mount the mesh filter 120 within the housing 110, a flange(not shown) could be joined to the vertical end of the cylindrical mesh filter 120 and an O-ring(not shown) would be inserted between the flange and the roof 105 of the housing 110. But detailed description is not given here since the related technology is well known and found anywhere. The area of the surface for capturing powders would be large enough to keep the vacuum pressure of the process chamber at adequate level even if a part of the mesh filter is clogged with the powder. The size of the mesh hole is determined according to the low limit size of the powder, that is, if the powder of more than 10/M in diameter would be captured, the mesh hole size would correspond to this value.

[32] The scrubber 100 further comprises a powder detaching means to detach powders from the mesh filter 120, and a sweeping gas injection device 130 is desirable as a powder detaching means, wherein a sweep gas is injected to the vertical inner surface of the mesh filter 120. As the sweeping gas is injected, vacuum suction is simultaneously applied to the discharge port 113 provided at the bottom of the funnel shaped hopper 110b, then the sweeping gas mixed with the detached powder is discharged from the housing 110 and enters into a vacuum suction means 140 such as a vacuum pump equipped with a dust bag. The vacuum suction means 140 would be further combined with a powder collecting means described later. The sweeping gas injection device 130 comprises : a sweeping gas supply tube 131 which penetrates the roof 105 of the housing and delivers the sweeping gas, a sweeping gas injection tube 132 connected to one end of the sweeping gas supply tube 131 to inject the sweeping gas to the inner surface of the mesh filter 120 from a nozzle 135 located near to the inner surface of the vertical mesh, a sweeping gas generation device 133 such as a compressed air port or an air compressor, and a nozzle driving device 130 to cover the whole inner surface of the vertical mesh by the trace of the nozzle 135. Then, the sweeping gas injected from the nozzle 135 detaches the powder P captured at the outer surface of the vertical mesh and flows into the vacuum suction means 140, thereby discharging the powder mixed with the sweeping gas from the housing 110 via the discharge port 113 provided at the bottom of the housing 110. The sweeping gas supply tube 131 and the sweeping gas injection tube 132 should be robust enough to withstand the rotation and up/down movement. A vertically flexible bellows 137 is provided between the roof 105 of the housing 110 and one end of the sweeping gas supply tube 131 in order to seal the housing 110 against the up/down movement of the sweeping gas supply tube 131. A bearing 134a such as a ball bush is provided at a part where the sweeping gas supply tube 131 penetrates the roof 105 to support both rotation and up/down movement. And another bearing 134b such as a retainer is provided at a part where the sweeping gas supply tube 131 penetrates the end bracket 138 of the bellows 137. [33] The nozzle driving device 130 which is provided at outside of the housing 110 comprises : a table 136a equipped with a bearing 134c such as an angular ball bearing to support the rotation of the sweeping gas supply tube 131, a motor 136b mounted at the table 136a, a belt and pulley device 136c to transfer the rotating power from the motor 136b to the sweeping gas supply tube 131, a lead screw 136d to raise and lower the table 136a, and a motor 136e to rotate the lead screw. Of course, the belt and pulley can be replaced by a set of gears and the lead screw can be replaced by a ball screw. As a result of this configuration, the sweeping gas injection tube 132 is rotated around the sweeping gas supply tube 131 and goes up and down. Then, the trace of the nozzle 135 from which the sweeping gas is injected covers the whole inner surface of the vertical mesh and the powders captured at the vertical outer surface of the mesh are detached. The shape of the nozzle 135 would be a circle or an ellipse whose long axis direction is vertical, and the inner diameter of the nozze is desirable at the range of 3 to 10mm. If the height of the mesh is relatively small or the injection gas flow rate is high enough, the size of the nozzle could be comparable to the height of the mesh filter.

[34] Fig. 4 shows the second embodiment of the scrubber according to the present invention. An inlet port 811 for the inflow of the exhaust gas released from a process chamber at the previous stage is provided at the side wall of the housing 810. A mesh filter 820 is provided at inside of the housing 810. The mesh filter 820 has a cylindrical shape. An outlet tube 812 is provided at upper part of the mesh filter 820. The vertical side of the mesh filter 820 is a mesh of a fibre form made from textures or steel wires, the outer surface of the mesh is the surface for capturing the powder P. A bearing 834a such as a retainer is provided at a part where the outlet tube 812 penetrates the housing 810, then the mesh filter 820 can be rotated around the outlet tube 812 while keeping sealing of the housing.

[35] A non-rotating ambiance supply port 825 is connected to the rotating outlet tube 812 through a second rotation supporting component 834b, the ambiance supply port 825 is branched into two ways : one way of the branch is to discharge the exhaust gas and the other way of the branch is to allow the inflow of a sweeping gas such as atmosphere. While the main process proceeds, the exhaust gas containing powders enters into the housing 810 via the inlet port 811 , is deprived of powders at the mesh filter 820, then goes out of the housing 810 by passing through the outlet tube 812, ambiance supply port 825, on/off valve 827, sequentially, and finally reaches to a process vacuum pump (not shown).

[36] And a powder detaching means to detach powders P from the mesh filter 820 comprises a rotating device to rotate the mesh filter 820 around the outlet tube 812 and a vertical suction beak 851 described below. The said rotating device is to rotate the outlet tube 812 mounted on the center of the roof of the mesh filter 820 and comprises components such as a set of a belt and pulleys 836 and a rotating motor 838.

[37] The said vertical suction beak 851 is provided near to the outer surface of the vertical mesh and connected to the vacuum suction means 840, thereby the powder is detached from the mesh by a co-operation of the vacuum suction exerted to the suction beak 851 and the inflow of the sweeping gas supplied to the inner surface of the vertical mesh via the intake valve 828 and the ambiance supply port 825. Then, the powder P detached from the mesh is discharged from the housing 810 to the vacuum suction means 840 via an exit 853 of the suction beak 851. Although a relatively positive pressure should be exerted on the inner surface of the vertical mesh, it is not necessary to inject the sweeping gas via a nozzle in contrast to the first embodiment of the present invention. Moreover, as shown in Fig. 5, it does not need to travel the suction beak 851 vertically as far as the vertical size of the suction beak 851 is comparable to the height of the mesh filter 820. However, there is a disadvantage that the suction beak 851 is easily contaminated by powders and the suction force might be weaker than the injecting force in contrast to the first embodiment of the present invention. Relatively heavy powders which is detached from the mesh filter 820 but accumulated at the bottom of the housing 810 may be independantly discharged to the vacuum suction means 840 via the discharge port 813 provided at the funnel shaped hopper 815 constituting the lower part of the housing 810.

[38] Fig. 6 shows a vertical cross-sectional view of a powder collecting means 500 which collects the powder detached from the mesh filter 120 or 820 of the first or second embodiment of the present invention. The powder collecting means 500 may be combined to the vacuum suction means as described later. The powder collecting means 500 comprises a second housing 510 determining an external shape, an inlet port 511 to allow an inflow of the sweeping gas mixed with the powder into the second housing 510, an outlet tube 512 to discharge the sweeping gas deprived of the powder from the second housing 510. The powder collecting means 500 further comprises a cylindrical second mesh filter 520 of which upper plate is provided with the said outlet tube 512 at the center. The sweeping gas mixed with the powder P must pass through the second mesh filter 520 before reaching to the outlet tube 512. The vertical surface of the second mesh filter 520 is a mesh and captures the powder at its outer surface. The bottom plate of the second mesh filter 510 is a flat board without holes. The second mesh filter 520 can be rotated around the said outlet tube 512 supported by a rotation supporting components such as a mechanical seal. The powder collecting means 500 further comprises a high speed rotating devices having components such as a set of a belt and pulleys 536, and a motor 538 as in the case of the second embodiment of the scrubber 800. Then, powders can be detached from the outer surface of the second mesh filter 520 by a centrifugal force resulted from the high speed rotation of the second mass filter 520. A funnel shaped hopper 515 constitutes the lower part of the second housing 510, and a discharge port 513 is provided at the bottom of the funnel shaped hopper 515 to discharge the accumulated powder from the second housing 510. A non-rotating ambiance supply port 525 is connected to the rotating outlet tube 512 through a second rotation supporting component 534b, and the ambiance supply port 525 is branched into two ways, one way of the branch with a valve 527 is to discharge the sweeping gas deprived of the powder to a vacuum suction means(not shown) and the other way of the branch with a valve 528 is to expose the internal ambiance of the second housing to the air.

[39] When the sweeping gas containing powders enters into the second housing 510 via the inlet port 511, the sweeping gas is deprived of powders at the second mesh filter 520, then goes out of the housing 510 by passing through the outlet tube 512, ambiance supply port 525, valve 527, sequentially, and finally reaches to a vacuum suction means(not shown). In order to detach powders captured at the vertical outer surface of the second mesh filter 520, the second mesh filter 520 is rotated at high speed around the outlet tube 512 at the speed of about more than 500rpm. While the second mesh filter 520 rotates at high speed, the internal condition of the second housing may be at vacuum pressure or maintain atmospheric pressure formed before the beginning of the rotation. Powders detached from the second mesh filter 510 by the high speed rotation of the second mesh filter 510 are accumulated at the bottom of the hopper 515 and collected to a collection bag(not shown) via the discharge port 513.

[40] Fig. 7 shows a schematic diagram of an exhaust gas treatment system in the semiconductor fabrication process equipped with a scrubber 100 of the present invention, the system comprising a process chamber 200 to process deposition or etching, an exhaust line 210, and a process vacuum pump 300. The scrubber 100 is provided between the process chamber 200 and the process vacuum pump 300. The inlet port 111 and outlet port 112 of the scrubber 200 are mounted on the scrubber 100. It is desirable to heat the exhaust line 210, for example, at the range of 150 to 200⁰C, since some kinds of exhaust gas condense on inner surface of the exhaust line 210 when the line temperature is reduced. A by-pass line 220 is provided to connect the process chamber 200 to the vacuum pump 300 directly and the on/off valves 231 to 234 are provided to selectively controlling the path of the exhaust gas to either the scrubber 200 or process vacuum pump 300. The second embodiment of the scrubber 800 shown in Fig. 4 may replace the scrubber 200 shown in Fig. 7. But additional descriptions or drawings are not presented here.

[41] The area of the surface for capturing powders in the mesh filter 120 would be large enough to keep the vacuum pressure of the process chamber 200 at adequate levels even if a part of the mesh filter is clogged with the powder. The desirable size of the mesh filter 120 is 200 to 400mm in diameter and 200 to 600mm in height. The size of the mesh hole would be determined by the low limit size of the powder. The mesh number of the mesh filter 120 would be higher than 150, that is, it is desirable that the mesh has more than 150 holes per square inch area. If the texture is used as a material for the fabri form mesh, the mesh hole size could be reduced below a few μm.

[42] The process flow based on the present invention is presented as follows. During the interval time when the finished substrate comes out of the process chamber and a new substrate is supplied into the process chamber, hazard gas is little contained in the exhaust gas. During this interval time, the on/off valves 232 and 234 of the scrubber 100 are closed and the valve 233 is opened. The exhaust gas is by-passed directly to the process vacuum pump 300. Then, if necessary, the exhaust gas passes through the next stage exhaust gas treatment system such as a wet type scrubber or a dry scrubber with charcoal or resin (not shown). While the main process such as deposition or etching is proceeding, the on/off valve 232 and 234 of the scrubber 100 are opened and the valve 233 of the by-pass line is closed, thereby the exhaust gas containing powders enters into the housing 110 of the scrubber 100 via the inlet port 111 and the powders are captured at the outer surface of the mesh filter 120. Then, exhaust gas deprived of powders goes out of the scrubber 100 via the outlet port 112. The powder captured at the outer surface of the mesh filter 120 is detached from the mesh filter 120 during the interval time for substrate exchanging as previously described. Referring to Fig. 2 again, the sweeping gas is injected from the nozzle 135 of the sweeping gas injection tube 132 to the inner surface of the mesh and vacuum suction is applied simultaneously to the discharge port 113 provided at the bottom of the funnel shaped hopper 110b, then the sweeping gas mixed with the detached powder is discharged from the housing 110 and enters into a vacuum suction means 140 such as a vacuum pump equipped with a dust bag or a powder collecting means 500 shown in Fig. 6.

[43] The sweeping gas is supplied from the sweeping gas generation device 133 such as a compressed air port or an air compressor, and the kind of the sweeping gas may be either clean air, nitrogen, or inert gas. Referring to Fig. 2 again, in order to cover the whole inner surface of the mesh, the sweeping gas injection tube 132 is rotated one revolution, then steps upward or downward. That is, the sweeping gas injection tube 132 is rotated one revolution around the sweeping gas supply tube 131 by motor 136b and rotation transfer components 136c such as a set of belt and pulley. Then, by motor 136e, lead screw 136d, and table 136a, the sweeping gas injection tube 132 goes up or down by a distance of about the size of the nozzle 135. And the step is repeated until the sweeping gas injection tube 132 reaches its high or low limit in vertical locations. However, if the nozzle size is comparable to the height of the mesh filter 120 the up/ down movement of the sweeping gas injection tube 132 would not be necessary. It is desirable that the supply pressure of the sweeping gas is 1 to 6bar, and it is very important that the sufficient flow rate of the sweeping gas is maintained. And the gap between the inner surface of the mesh and the nozzle is desirable at the range of 5 to 10mm.

[44] Fig. 8 shows another example of the present invention for the exhaust gas treatment system in semiconductor fabrication process. A powder generation means 400 is further provided between the process chamber 200 and the scrubber 100 to generate powders positively from the exhaust gas, wherein a plurality of bar or U shaped cartridge heaters 410 are included in the powder generation means 400. As far as the cartridge heater 410 is heated to a proper level, such as at the temperature between 300 to 500⁰C, the exhaust gas entered into the powder generation means 400 via an inlet port 411 makes a deposition on the surface of the cartridge heater 410 as a result of surface reactions such as pyrolysis, re-combination, and etc. The exhaust gas can also generate powders by gas phase reaction. The powder generated by the gas phase reaction is discharged from the powder generation means 400 via an outlet port 412 and enters into the scrubber 100. The surface of the cartridge heater 410 experiences equilibrium state of depositing and flaking off of powders, and most of powders flaked off from the surface of the cartridge heater enters into the scrubber 100 with the exhaust gas. But relatively heavy powders are accumulated at the bottom of the funnel shape hopper 415 constituting the lower part of the powder generation means 400. In case that powders are accumulated at the bottom of the hopper 415 of the powder generation means 400, the powders should be periodically removed from the hopper 415 using the method described previously in case of detachment of powders from the mesh filter 120 of the scrubber 100 shown in Fig. 2. Meanwhile, it is desirable to heat the exhaust line between the process chamber 200 and the powder generation means 400 to prevent the condensation of the exhaust gas on inner surfaces of the exhaust line 210, where the surface temperature of the exhaust gas line would be between 150 to 25O⁰C.

[45] The powder generation means 400 could adopt plasma trap (not shown) instead of cartridge heater 410, where electrode plates of anode and cathode are piled alternatively. Plasma is generated between the electrode plates, and the plates are simultaneously heated to proper levers such as below 400⁰C. Then the exhaust gas undergoes surface reactions on the surface of the plates to induce depositions on the plates. However, the electric field in the plasma trap may be greatly reduced as the deposition on the electrode plate goes on, which makes it inevitable to replace the electrode plate periodically. Although the descriptions are not presented again, electrostatic collection, cold trap, or re -burning method described previously could be adopted too. It is not determined in the same breath whether the powder generation means should be surface reaction type or other type. For example, when metal-organic compounds are used as source materials, the materials have usually low decomposition temperature and those easily make reactions at gas phase or on heated surfaces. Therefore, the surface reaction type would be more effective in the process using metal-organic compounds. Re-burning method would be preferred in the process where silicon containing gasses are exhausted, since silicon dioxide(SiO ) can be readily generated from the exhaust gas by re -burning of the exhaust gas.

[46] A vacuum pump equipped with a dust bag could be used to collect the powders accumulated at the bottom of the hopper 415 of the powder generation means 400 or the powders detached from the mesh filter 120. But more effectively the powder collecting means 500 in Fig. 6 can be used as described in detail previously. As shown in Fig. 8, powder collecting means 500 is connected to next of powder generation means 400 and scrubber 100 via the discharge lines 241 and 242, respectively.

[47] The final stage of the collection process for the powders accumulated at the bottom of the powder collecting means 500 is presented now. The internal pressure of the powder collecting means is slowly reset to atmospheric pressure by regulating the throttle valve 528. And a collection bag 550 is placed under the discharge valve 542. Then, by opening the discharge valve 542 the powders go into the collection bag 550 by gravity.

[48] There may happen second contamination such as dispersion of dust into the air during the process to collect the powders into the collection bag 550. In this regards it is preferable that the powder collecting means 500 is located at non-clean region separated from the clean region where the main process is processed. The powder collecting means may be even located in a sealed box having a ventilation system.

[49] While this invention has been described and illustrated with reference to particular embodiments, it will be readily apparent to those skilled in the art that the scope of the present invention is not limited to the disclosed embodiments, but is intended to cover numerous other modifications and equivalent arrangements. Industrial Applicability

[50] The present invention would be widely used in the semiconductor fabrication industry for the exhaust gas treatment system to realize high level productivity and environmental consideration. Metal-organic compounds are very promising materials for fabricating conducting materials and insulating materials in conventional semiconductor industries and must be the key material for multi-component new devices such as high-k DRAM, solar cell, LED, and/or ink jet print head. But there have been some problems of the metal-organic materials, since the material requires difficulty in handling, is very sensitive to moisture in most cases, and produces powders easily within the processing lines. In this regards this invention would be most effectively used in semiconductor industry where metal-organic compounds are used as source materials.

Claims

[1] A scrubber equipped with a mesh filter comprising : a housing provided with an inlet port and an outlet port for an exhaust gas, a mesh filter which is placed between the inlet port and outlet port of the housing, passes the exhaust gas through, and captures powders contained in the exhaust gas at a capturing surface thereof, a powder detaching means to detach powders captured at the capturing surface of the mesh filter; and a discharge port which is provided at a side of the housing and connected to a vacuum suction means to release the powders detached from the housing.

[2] The scrubber equipped with a mesh filter of claim 1, wherein : the mesh filter has a cylindrical shape, the upper part of the mesh filter constitutes a part of the roof of the housing, the vertical side of the mesh filter is a mesh, the outer surface of the mesh is the powder capturing surface, and the bottom plate of the mesh filter is a flat board; and the powder detaching means comprises a sweeping gas supply tube penetrating the center of the roof of the housing, a sweeping gas injection tube connected to one end of the sweeping gas supply tube to inject the sweeping gas to the inner surface of the mesh from a nozzle located near to the inner surface of the mesh, a sweeping gas generation device such as a compressed air port or an air compressor, and a nozzle driving device to cover the whole inner surface of the vertical mesh by the trace of the nozzle, so that the sweeping gas injected from the nozzle detaches the powder captured at the outer surface of the mesh and is forced to flow into the vacuum suction means, thereby discharging the powder mixed with the sweeping gas from the housing via the said discharge port.

[3] The scrubber equipped with a mesh filter of claim 1, wherein : the mesh filter has a cylindrical shape, the said outlet tube is installed at the center of the upper plate of the mesh filter, the vertical side of the mesh filter is a mesh, the outer surface of the vertical mesh is the powder capturing surface, the bottom plate of the mesh filter is a flat board, the outlet tube penetrates a part of the roof of the housing with the help of a first rotation supporting components to allow a rotation of the mesh filter around the outlet tube while keeping the sealing of the housing, a non-rotating ambiance supplying port is connected to the said outlet tube with the help of a second rotation supporting component, the said ambiance supply port is branched into two ways, one way of the branch to discharge the exhaust gas and the other way of the branch to allow the inflow of a sweeping gas; and the powder detaching means include a vertical suction beak provided near to the outer surface of the vertical mesh and connected to the said vacuum suction means, so that the powder is discharged from the said housing to the vacuum suction means via the vertical suction beak after being detached from the said mesh filter by a co-operation of the vacuum suction exerted to the suction beak and the inflow of the sweeping gas supplied via the ambiance port to the inner surface of the vertical mesh, and the powder can be independently discharged from the said housing to the vacuum suction means via the said discharge port.

[4] The scrubber equipped with a mesh filter of one of the claims 1, 2, and 3, wherein a funnel shaped hopper is provided to constitute the lower part of the housing and a discharge port is provided at the bottom of the said hopper.

[5] The scrubber equipped with a mesh filter of one of the claims 1, 2, and 3, wherein the said vacuum suction means is additionally combined with a powder collecting means comprising : a second housing provided with an inlet port to allow an inflow of the sweeping gas mixed with the powder and an outlet tube to discharge the sweeping gas deprived of the powder, a second mesh filter of a cylindrical shape provided between the inlet port and outlet tube, through which the sweeping gas mixed with the powder must pass to reach to the outlet tube, of which upper plate is provided with the said outlet tube at the center, which is rotated around the said outlet tube supported by a rotating support component at the part where the outlet tube penetrates the roof of the second housing, of which vertical surface is a mesh, of which bottom plate is a flat board, and which captures the powders contained in the sweeping gas at the outer surface of the said mesh. a high speed rotating device to rotate the second mesh filter at high speed around the said outlet tube and to detach the powder captured at the mesh of the second mesh filter as a result of the generated centrifugal force, a funnel shaped hopper constituting the lower part of the second housing; and a discharge port provided at the bottom of the funnel shaped hopper to discharge the accumulated powder from the housing.

[6] An exhaust gas treatment system of the semiconductor fabrication equipments comprising : a process chamber to perform a fabrication process of the semiconductor devices, a process vacuum pump to inhale the exhaust gas from the process chamber, the said scrubber equipped with a mesh filter of one of the claims 1, 2, and 3 which is installed between the process chamber and the process vacuum pump, a by-pass line which connects the process chamber directly to the process vacuum pump; and on/off valves controlling the flow of the exhaust gas from the process chamber to either the scrubber or the process vacuum pump.

[7] The exhaust gas treatment system of the semiconductor fabrication equipments of claim 6, wherein the said vacuum suction means is additionally combined with a powder collecting means comprising : a second housing provided with an inlet port to allow an inflow of the sweeping gas mixed with the powder and an outlet tube to discharge the sweeping gas deprived of the powder, a second mesh filter of a cylindrical shape provided between the inlet port and outlet tube, through which the sweeping gas mixed with the powder must pass to reach to the outlet tube, of which upper plate is provided with the said outlet tube at the center, which is rotated around the said outlet tube supported by a rotating support component at the part where the outlet tube penetrates the roof of the second housing, of which vertical surface is a mesh, of which bottom plate is a flat board, and which captures the powders contained in the sweeping gas at the outer surface of the said mesh. a high speed rotating device to rotate the second mesh filter at high speed around the said outlet tube and to detach the powder captured at the mesh of the second mesh filter as a result of the generated centrifugal force, a funnel shaped hopper constituting the lower part of the second housing; and a discharge port provided at the bottom of the funnel shaped hopper to discharge the accumulated powder from the housing.

[8] The exhaust gas treatment system of the semiconductor fabrication equipments of claim 6 further comprising a powder generation means provided between the process chamber and the said scrubber equipped with a mass filter to generate powders from the exhaust gas.

[9] The exhaust gas treatment system of the semiconductor fabrication equipments of claim 8, wherein the powder generation means includes a plurality of bar or U shaped cartridge heaters at inside of the powder generation means and induces surface reactions on the surface of the cartridge heaters by heating.

[10] The exhaust gas treatment system of the semiconductor fabrication equipments of claim 8, wherein a funnel shaped hopper constitutes the lower part of the powder generation means, a discharge port is provided at the bottom of the funnel shaped hopper, and the discharge port is connected to the discharge port of the said scrubber equipped with a mass filter.

[11] The exhaust gas treatment system of the semiconductor fabrication equipments of claim 7 further comprising a powder generation means provided between the process chamber and the said scrubber equipped with a mass filter to generate powders from the exhaust gas.

[12] The exhaust gas treatment system of the semiconductor fabrication equipments of claim 11, wherein the powder generation means includes a plurality of bar or U shaped cartridge heaters at inside of the powder generation means and induces surface reactions on the surface of the cartridge heaters by heating.

[13] The exhaust gas treatment system of the semiconductor fabrication equipments of claim 11, wherein a funnel shaped hopper constitutes the lower part of the powder generation means, a discharge port is provided at the bottom of the funnel shaped hopper, and the discharge port is connected to the discharge port of the said scrubber equipped with a mass filter.