Patent Abstract:
A particle adsorption device includes a chamber having an inlet and an outlet by which air can pass through the chamber, a support for supporting an adsorbent plate in the chamber, and at least one porous plate disposed in the chamber to control the air flow through the chamber and over a surface of the adsorbent plate. A sampling apparatus includes a particle counter which has a detector that is operative to count particles of a certain size contained in the air, the particle adsorption device, and a probe by which a sample of air is sequentially or selectively fed to the particle adsorption device and the particle counter. Thus, in a method for use in monitoring a manufacturing environment for potential contamination, particles of a certain size in the air can be counted, and particles in the air can be collected on the surface of the adsorbent plate. The collected particles can be analyzed to determine their shape and composition. Te source of the particles can be traced from data produced using the sampling apparatus.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a sampling method of and apparatus for analyzing an environment for its particle content. More particularly, the present invention relates to methods of and apparatus for detecting particles as potential contaminants in an environment in which a certain level of cleanness is to be maintained, such as in a clean room of a semiconductor device manufacturing facility.  
         [0003]     2. Description of the Related Art  
         [0004]     A semiconductor device is an extremely elaborate device fabricated by repeatedly performing a plurality of processes including photolithography, diffusion, etching, and deposition processes on a semiconductor wafer. These processes must be carried out precisely, i.e., under strict process conditions, and in an environment having a high level of cleanness. Otherwise, particles will contaminate the semiconductor wafer and cause defects to occur.  
         [0005]     A surface particle counter or air particle counter is generally used to maintain a proper state of cleanness in a semiconductor device fabrication facility. The surface particle counter or air particle counter collects a sample of air using a pump, e.g., a GAST pump, and counts the number of particles in the sample of the air. In particular, the surface particle counter blows air onto a surface which has been exposed in the facility and suctions the air rebounding from the surface using the pump, whereas the air particle counter only suctions air in the facility using the-pump. The results obtained from the surface particle counter or air particle are used to schedule maintenance or otherwise monitor the facility for contamination.  
         [0006]      FIG. 1  illustrates a conventional surface particle counter  10 . The surface particle counter  10  includes a housing  18  in which an exhaust fan  17  is installed, and a pump  11 , e.g., a GAST pump, disposed inside the housing  18 . A probe  15  is connected to both the intake and exhaust sides of the pump  11  to blow air onto and suction air from a surface of an object  50  that has come from the semiconductor device fabrication facility. The arrows in the figure indicate the direction of air flow through the surface particle counter  10 . A particle detector  16  measures the size and number of particles contained in air introduced thereto through the probe  15 . Air that has passed through the particle detector  16  is filtered and purified by a first filter  13 , e.g., a DUST filter, and a second filter  14 , e.g., a ZERO filter. The purified air is blown back outside the housing  18  through the probe  15 . A flow control valve  12  controls the flow of air through the filters  13 ,  14  and back out the probe  15 .  
         [0007]      FIG. 2  is a flowchart illustrating the operation of the conventional surface particle counter  10 . Referring to  FIGS. 1 and 2 , the pump  11  begins to operate when power is supplied to the surface particle counter  10  (S 11 ). As a result, air is blown out of and suctioned back through the probe  15  (S 15 ). The flow rate of the exhaust (air blown out of the probe  15 ) is controlled by the flow control valve  12  (S 12 ). Particles are separated from a surface of the object  50  by the exhaust (S 15   a ). Air containing the particles separated from the object  50  is sucked back into the probe  15  by the pump  11  (S 15   b ). The air induced into the probe  15  by suction is introduced into the particle detector  16  where the number of particles contained in the air is counted (S 16 ). Air that has passed through the particle detector  16  flows back through the pump  11  and is exhausted at a rate controlled, again, by the flow control valve  12  (S 12 ). Relatively large particles are removed from the air by the first filter  13  (first filtering S 13 ), and then relatively small particles are removed from the air by the second filter  14  (second filtering S 14 ).  
         [0008]     Similar to the conventional surface particle counter, a conventional air particle counter suctions air through a probe and measures the number of particles contained in the air using a particle detector. However, in this case the air is a sample of the environment in which the fabrication process is being carried out.  
         [0009]     As described above, the conventional surface particle counter samples air blown onto an object exposed to an environment in which a semiconductor device is fabricated. A conventional air particle counter samples air directly from the environment itself. Each of the conventional particle counters employs a particle detector to count numbers of particles of certain sizes. The results are used to maintain and manage the cleanness of the environment in which the semiconductor devices are being fabricated.  
         [0010]     However, the conventional particle counters merely provide numerical results regarding the sizes of particles in the collected samples. That is, conventional particle counters do not provide a determination of the composition, shape, or cause of particles in the air.  
       SUMMARY OF THE INVENTION  
       [0011]     Objects of the present invention are to provide a device, an apparatus and a method by which the source or cause of particles in a manufacturing environment or the like can be determined with a high degree of reliability.  
         [0012]     According to one aspect of the present invention, a particle adsorption device includes a chamber, an adsorption plate, a support disposed inside the chamber and configured to support the adsorption plate, and at least one porous plate disposed in an air flow path within the chamber. The chamber has an inlet and an outlet through which air can pass into and out of the chamber along the air flow path. A surface of the adsorption plate is exposed to air entering the chamber through the inlet. Thus, a surface of the adsorption plate will adsorb the air and thereby trap particles contained in the air on the surface. Pores of the at least one porous plate are arranged to stabilize air introduced into the chamber through the inlet at a given rate.  
         [0013]     The at least one porous plate may include a first porous plate disposed to one side of the adsorption plate and a second porous plate disposed to the other side of the adsorption plate. In addition, a third porous plate may be disposed on an opposite side of the first porous plate from the adsorption plate. In this case, pores of the third porous plate are arranged to distribute air entering the inlet of the chamber such that the air is not concentrated on a predetermined region of the adsorption plate. In particular, the pores of the third porous plate include a plurality of first through-holes and a plurality of second through-holes. The first through-holes are concentrated at a central portion of the third porous plate and have a diameter smaller than that of the second through-holes.  
         [0014]     The chamber of the particle adsorption device may include a chamber body having a respective opening in an upper and/or a lower portion thereof, and a respective cover sealing each opening. The cover includes a projection extending into the chamber body. The projection has a frustum-shaped concavity therein constituting a portion of the air flow path within the chamber.  
         [0015]     According to another aspect of the present invention, the particle adsorption device is integrated with a particle detector to form a sampling apparatus. According to this aspect of the present invention, air lines connect the chamber of the particle adsorption device to the particle detector of the particle counter.  
         [0016]     According to still another aspect of the present invention, the sampling apparatus also includes a pump having an intake side at which the pump creates a vacuum and an exhaust side at which air is forced from the pump, and a probe. In this case, the air lines which connect the chamber of the particle adsorption device to the particle detector are part of a system of lines that include an exhaust line extending from the exhaust side of the pump, and a vacuum line leading to the vacuum side of the pump. The probe is connected to the vacuum line at an end of the vacuum line. Thus, air can be sucked into the vacuum line through the probe when the pump is running.  
         [0017]     The particle detector and the chamber of the particle adsorption device may be disposed in series in the vacuum line between the probe and the intake side of the pump. Alternatively, the vacuum line has a first branch, and a second branch extending from the probe. The first and second branches diverge between the probe and the inlet of the chamber of the particle adsorption device. The particle counter is disposed at the end of the second branch of the vacuum line. Several flow directional control valves may be provided in the lines to control the direction of flow of air through the lines.  
         [0018]     For instance, a first directional flow control valve is disposed in the vacuum line between the outlet of the chamber of the particle adsorption device and the intake side of the pump, and a second directional flow control valve is disposed in the vacuum line at the location at which the first and second branches of the vacuum line diverge. In addition, a third flow directional control valve may be disposed in the first branch of the vacuum line. Each of the valves may be a 3-way solenoid valve. Filters may be connected to the vacuum line through the second and third flow directional control valves, respectively. Another filter may be provided in the exhaust line.  
         [0019]     According to another aspect of the present invention, a sampling method includes collecting a sample of air using suction, detecting particles of a certain size in the sample of air and counting the number of particles, and adsorbing air from the sample by passing the air over an adsorbent medium to thereby trap particles in the air on a surface of the medium. The particles trapped on the surface of the medium can then be analyzed to determine, for example, their shape and composition.  
         [0020]     According to still another aspect of the present invention, a sampling method includes drawing air into and through a probe, directing air that is drawn through the probe to a particle counter that detects particles of a certain size and counts the number of particles, and directing air that is drawn through the probe over the surface of an adsorbent medium supported in a hermetic chamber of a particle adsorption device. The air is adsorbed by the medium to trap particles suspended in the air on the surface of the medium.  
         [0021]     The air is drawn in through the probe by a vacuum created using a pump. The air drawn in through the probe may be directed sequentially from one of the chamber of the particle detection device and the particle detector to the other. Alternatively, air drawn in through the probe is selectively directed to the chamber of the particle detection device and the particle detector. In the latter case, air may be drawn into the particle detector of the particle counter using a pump of the particle counter while air is being directed from the probe to the chamber of the particle detection device.  
         [0022]     Also, air may be blown out through the probe and onto the surface of an object using a pump while air is being drawn into the probe using the pump. The air blown out of the probe is used to dislodge particles from the surface of the object. The air may be purified before it is blown out through the probe.  
         [0023]     Finally, the adsorbent medium may be removed from the hermetic chamber so that the particles trapped on the surface of the medium can be analyzed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     These and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the invention made with reference to the accompanying drawings. In the drawings:  
         [0025]      FIG. 1  is a schematic diagram of a conventional sampling apparatus;  
         [0026]      FIG. 2  is a flowchart of the operation of the conventional sampling apparatus;  
         [0027]      FIG. 3  is a schematic diagram of a first embodiment of a particle sampling apparatus according to the present invention;  
         [0028]      FIG. 4  is a flowchart of a first embodiment of a sampling method for use in analyzing an environment according to the present invention;  
         [0029]      FIG. 5  is a schematic diagram of a second embodiment of a particle sampling apparatus according to the present invention;  
         [0030]      FIG. 6  is a flowchart of a second embodiment of a sampling method for use in analyzing an environment according to the present invention;  
         [0031]      FIG. 7  is a perspective view of an adsorption device of the first embodiment of a particle sampling apparatus according to the present invention;  
         [0032]      FIG. 8  is an exploded perspective view of the adsorption device;  
         [0033]      FIG. 9  is a plan view of a porous plate of the adsorption device;  
         [0034]      FIG. 10  is a plan view of another porous plate of the adsorption device;  
         [0035]      FIG. 11  is a perspective view of a chamber cover of the adsorption device;  
         [0036]      FIG. 12  is a cross-sectional view of the chamber cover;  
         [0037]      FIG. 13  is a schematic diagram of a third embodiment of a sampling apparatus according to the present invention;  
         [0038]      FIG. 14  is a schematic diagram of the third embodiment of the sampling apparatus according to the present invention while in a particle detection mode;  
         [0039]      FIG. 15  is a flowchart of the particle detection mode of the third embodiment of the sampling apparatus in according to the present invention;  
         [0040]      FIG. 16  is a schematic diagram of the third embodiment of the sampling apparatus according to the present invention while in a particle adsorption mode; and  
         [0041]      FIG. 17  is a flowchart of the particle adsorption mode of the third embodiment of the sampling apparatus according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]     Referring to  FIG. 3 , a first embodiment of a particle sampling apparatus  100  includes a particle counter  111  and an adsorption device  190  coupled to the particle counter  111 . The particle counter  111  determines the sizes of particles entrained in a sample of air and counts the number of particles of each size, and the adsorption device  190  is used to determine the shape, composition, and source of the particles.  
         [0043]     The particle counter  111  includes a pump  110  having an exhaust side at which pressure is created and an intake side at which a vacuum is created, a flow control valve  120 , a first filter  130  and a second filter  140  disposed in-line with the pump  110  at the exhaust side of the pump  110 , a probe  150  connected to both the exhaust side and the intake side of the pump  110 , and a particle detector  160  disposed in-line with the pump  110  at the intake side of the pump  110 . The pump  110  is a GAST pump, for example. The pump  110  is disposed inside a housing  180 . An exhaust fan  170  is mounted to the housing  180 .  
         [0044]     More specifically, an exhaust line  112  extends from the exhaust side of the pump  110 , and a vacuum line  114  leads to the intake side of the pump  110 . The probe  150  is connected to respective ends of the lines  112  and  114  so that air flowing through the exhaust line  112  is blown out of the probe  150  and air outside the probe  150  is induced into the vacuum line  114  though the probe  150 . The probe  150  may be positioned to face an object  510  such that air blown out of the probe impinges the object  510  to dislodge particles from the object, and such that air containing the particles is sucked into the probe  150 . The object  510  may be one that is exposed within a fabrication facility, e.g., a clean room of a semiconductor device manufacturing facility. Alternatively, the probe  150  is disposed in the fabrication facility to merely collect a sample of air from the environment within the facility. In the latter case, the end of the exhaust line  112  leading to the probe  150  can be omitted.  
         [0045]     The flow control valve  120  controls the flow of air through the exhaust line  112 , i.e., regulates the rate of flow of the air. The first filter  130  is for filtering out relatively large foreign particles from the air flowing through the exhaust line  112 . The first filter  130  is a DUST filter, for example. The second filter  140  is for filtering out relatively small foreign particles in the air flowing through the exhaust line  112 . The second filter  140  is a ZERO filter, for example.  
         [0046]     Particles in the air induced into the vacuum line  114  through the probe  150  flow along with the air to the particle detector  160 . The particle detector  160  determines the sizes of particles entrained in the air taken in through the probe  150  and counts the number of particles of each size. In this respect, the particle detector  160  is conventional per se and thus, a detailed description thereof will be omitted. Also, note, counting the number of particles of “each size” can refer to counting. particles whose diameters are within given numerical ranges.  
         [0047]     The adsorption device  190  is disposed in-line with the pump  110  of the particle counter  111  at the intake side of the pump  110 . Specifically, the adsorption device  190  is disposed in the vacuum line  114  downstream of the particle detector  160  with respect to the direction of flow of the air through the vacuum line  114 . Thus, particles in the air induced into the vacuum line  114  through the probe  150  flow along with the air to the adsorption device  190  after having passed through the particle detector  160 . The adsorption device  190  will now be described in more detail with reference to  FIGS. 7 and 8 .  
         [0048]     The adsorption device  190  has a hermetic chamber formed of a chamber body  194 , an upper chamber cover  191  and a lower chamber cover  197 . The chamber body  194  has (circular) openings in an upper portion and a lower portion thereof and a door at one side thereof. The upper chamber cover  191  and lower chamber cover  197  are fitted to the openings in the upper portion and a lower portion of the chamber body  194 , respectively, to cover the chamber body  194 . A chuck (support)  195  is inserted in the chamber body  194 . The adsorption chamber  190  also has an adsorption plate  198  supported by the chuck  195  within the chamber body  194 . The adsorption plate  198  can be a bare wafer but is not limited thereto. Any medium that can adsorb air can be used for the adsorption-plate  198 . The adsorption plate  198  can be removed from the chamber body  194  through the door thereof. Specifically, the opening in the side of the chamber body closed by the door is wider than that of the adsorption plate  198 . Thus, the adsorption plate  198  can be removed from the chamber body  194  so that particles trapped on the surface of the adsorption plate  198  can be analyzed outside the chamber body  194 .  
         [0049]     Air flowing through the vacuum line  114  passes into the chamber body  194  through an inlet ( FIGS. 11, 12 ) in the upper chamber cover  191 . The air is adsorbed by a surface of the adsorption plate  198  within the chamber body  194  so that particles contained in the air are trapped. The remaining (non-adsorbed) air passes back into the vacuum line  114  through an outlet ( FIGS. 11, 12 ) in the lower chamber cover  197 , and flows to the pump  110 . A vacuum is maintained inside the chamber body  194  by the pump  110 .  
         [0050]     In addition, the adsorption chamber  190  includes porous plates inside the chamber body  140 . More specifically, the plates include a first upper porous plate  192  and a second upper porous plate  193  disposed above the adsorption plate  198 , and a lower porous plate  196  disposed below the adsorption plate  198 . The porous plates  193 ,  196  stabilize the flow of air through the adsorption chamber  190 . The porous plate  192  prevents a concentration of particles from being adsorbed at a particular region of the adsorption plate  198 . The porous plates  192 ,  193  and  196  can be supported and spaced apart from one another within the chamber body  194  by any suitable fixtures/spacers.  
         [0051]     Referring to  FIG. 9 , the first upper porous plate  192  includes a plurality of through-holes (pores)  192   a  each having a relatively small diameter and a plurality of through-holes (pores)  192   b  each having a relatively large diameter. The holes  192   a  are concentrated in a central portion of the first upper porous plate  192  to prevent air introduced through the upper cover  191  from being concentrated at a central portion of the adsorption plate  198 . The size and number of the holes  192   a  and  192   b  depend on the size of the adsorption plate  198 , the flow rate of the air through the adsorption chamber  190 , etc. When the adsorption plate  198  is an 8-inch bare wafer and the air is regulated to flow at a rate of about 1 CFM (cubic feet per minute), for example, the holes  192   a  have a diameter of about 5 mm and the holes  192   b  have a diameter of about 10 mm.  
         [0052]     Referring to  FIG. 10 , the second upper porous plate  193  has a plurality of holes (pores)  193   a  each having a predetermined diameter and which are uniformly distributed across the plate  193 . Like the second upper porous plate  193 , the lower porous plate  196  has a plurality of holes  196   a  each having a predetermined diameter and which are uniformly distributed across the plate  196 . The size and number of the holes  193   a ,  196   a  depend on the flow rate of the air, etc. The holes  193   a ,  196   a  each have a diameter of about 5 mm when the flow rate of the air through the adsorption chamber  190  is about 1 CFM, example. The lower porous plate  196  minimizes the swirling or back flow of air that is introduced after particles are adsorbed by the adsorption plate  198 .  
         [0053]     Referring to  FIGS. 11 and 12 , the upper chamber cover  191  has a (circular) projection having a concavity in the form of a frustum A contiguous with the inlet. The projection is fitted to the chamber body  194  within the opening in the upper portion thereof to seal the opening. The concavity is defined by an inclined inner wall  191   a . The diameter of the concavity increases in a direction away from the inlet. Air introduced through the inlet in the upper chamber cover  191  flows along the inclined inner wall  191   a  such that the air is guided over a wide area. Therefore, the upper chamber cover  191  facilitates the forming of a uniform air flow within the adsorption device  190 . The lower chamber cover  197  may also have a (circular) projection fitted to the opening in the lower portion of the chamber body  194 , an inclined inner wall  191   a  of the projection defining a concavity in the form of a frustum A contiguous with the outlet in the lower chamber cover  197 , as indicated in  FIG. 11 .  
         [0054]     Referring back to  FIG. 3 , the air flows into the exhaust line  112  via the pump  110  after having passed through the particle detector  160  and the adsorption chamber  190 . There the air passes through the first filter  130  and the second filter  140  so as to be purified. The purified air is then blown out through the probe  150  onto the surface of object  510  or into the environment. At the same time, air is induced into the vacuum line  114  through the probe  150 . During this time, the flow control valve  120  controls the rate at which the air is blown out of the probe  150 . The present invention samples the environment directly or indirectly (via an object  510  exposed to the environment) through the continuous action of blowing air out of and suctioning air into the probe.  
         [0055]     A sampling method according to the present invention will be described with reference to  FIGS. 3 and 4 .  
         [0056]     Referring to  FIG. 4 , power is supplied to the sampling apparatus  100  to start the pump  110  (S 111 ). As a result, air is blown out of and sucked back into the probe  150  (S 150 ). The rate at which the air flows out of the probe  150  is controlled by the flow control valve  120  (S 120 ). Also, relatively large particles are filtered from the air by the first filter  130  (S 130 ), and then relatively small particles are secondly filtered from the air by the second filter  140  (S 140 ) before the air reaches the probe  150 .  
         [0057]     Air blown out of the probe  150  dislodges particles from a surface of the object  510  (S 150   a ). Alternatively, the probe may be located in a facility whose air is to be monitored directly. In either case, air containing particles is sucked into the probe  150  by the vacuum created by the pump  110  (S 150   b ). The air sucked into the probe  150  is then introduced to the particle detector  160 , where data indicating the sizes and the number of particles of each size is produced (S 160 ). Air that has passed through the particle detector  160  is introduced into the adsorption chamber  190 . Therefore, particles contained in the air are adsorbed by a surface of the adsorption plate  198  (S 190 ). Then, the adsorption plate  198  is scanned by an apparatus such as a conventional process defect detection measurement apparatus, a scanning electron microscope (SEM), or a SEM equipped with an X-ray analyzer for producing data indicative of the shape and/or composition of particles trapped on the adsorption plate  198 . The data can be analyzed to reveal the source or cause of the particles. Air that has passed through the adsorption chamber  190  is regulated to flow at a given rate (S 120 ), is filtered (S 130 , S 140 ), and is blown back out of the probe  150  (S 150 ). At the same time, air containing particles is being sucked into the probe  150  (S 150 ).  
         [0058]     As described above, exhaust and suction processes (S 150 ) are carried out continuously and simultaneously to sample particles from a surface of the object  510  or in the air of a manufacturing environment. The sampling is used to obtain data of the size and number of particles of each size. At the same time, particles are collected and can be analyzed to obtain data on the shape and/or composition of the particles. As a result, the source or cause of the particles can be pin-pointed.  
         [0059]      FIG. 5  illustrates a second embodiment of a sampling apparatus  200  according to the present invention. Referring to  FIG. 5 , the second embodiment of the sampling apparatus  200  includes a particle counter  211  and an adsorption device coupled to the particle counter  211 . The particle counter  211  includes a pump  210  having an exhaust side at which pressure is created and an intake side at which a vacuum is created, a flow control valve  220 , a first filter  230  and a second filter  240  disposed in-line with the pump  210  at the exhaust side of the pump  210 , a probe  250  connected to both the exhaust side and the intake side of the pump  210 , and a particle detector  260  disposed in-line with the pump  210  at the intake side of the pump  210 . The pump  210  is a GAST pump, for example. The pump  210  is disposed inside a housing  280 . An exhaust fan  270  is mounted to the housing  180 .  
         [0060]     An exhaust line  212  extends from the exhaust side of the pump  210 , and a vacuum line  214  leads to the intake side of the pump  210 . The probe  250  is connected to respective ends of the lines  212  and  214  so that air flowing through the exhaust line  212  is blown out of the probe  250  and air outside the probe  250  is induced into the vacuum line  214  though the probe  250 . The probe  250  may be positioned to face an object  520  such that air blown out of the probe impinges the object  520  to dislodge particles from the object, and such that air containing the particles is sucked into the probe  250 . The object  520  may be one that is exposed within a fabrication facility, e.g., a clean room of a semiconductor device manufacturing facility. Alternatively, the probe  250  is disposed in the fabrication facility to merely collect a sample of air from the environment within the facility. In the latter case, the end of the exhaust line  212  leading to the probe  250  can be omitted.  
         [0061]     The structure and function of the adsorption device  290  are the same as those shown in and described with reference to FIGS.  9  to  12 . The sampling apparatus  200  is essentially the same as that of the first embodiment except that the adsorption chamber  290  is disposed upstream of the particle detector  260  with respect to the direction of flow of air through the vacuum line  214 .  
         [0062]     Referring to  FIGS. 5 and 6 , power is supplied to the sampling apparatus  200  to start the pump  210  (S 211 ). As a result, air is blown out of and sucked back into the probe  250  (S 250 ). The rate at which the air flows out of the probe  250  is controlled by the flow control valve  220  (S 220 ). Also, relatively large particles are filtered from the air by the first filter  230  (S 230 ), and then relatively small particles are secondly filtered from the air by the second filter  240  (S 240 ) before the air reaches the probe  250 .  
         [0063]     Air blown out of the probe  250  separates particles from a surface of the object  520  (S 250   a ). Alternatively, the probe may be located in a facility whose air is to be monitored directly. In either case, air containing particles is sucked into the probe  250  by the vacuum created by the pump  210  (S 250   b ). The air sucked into the probe  250  is then introduced to the chamber of the adsorption device  290 . Therefore, air is adsorbed by a surface of the adsorption plate (S 290 ) to trap particles contained in the air on the surface. Then, an apparatus such as a conventional process defect detection measurement apparatus, a scanning electron microscope (SEM), or a SEM equipped with an X-ray analyzer is used for examining the particles on the adsorption plate to produce data indicative of the shape and/or composition of the particles.  
         [0064]     Air that has passed through the adsorption device  290  is then introduced to the particle detector  260 , where data indicating the sizes and the number of particles of each size is produced (S 260 ). However, in this case, an analysis of the data produced by the particle detector  260  will take into account that many of the particles from the sample have been trapped in the adsorption device  290 . Air that has passed through the particle detector  260  is regulated to flow at a given rate (S 220 ), is filtered (S 230 , S 240 ), and is blown back out of the probe  250  (S 250 ). At the same time, air containing particles is being sucked into the probe  250  (S 250 ).  
         [0065]     A third embodiment of a sampling apparatus  300  according to the present invention will now be described with reference to  FIG. 13 . A pump  310 , e.g., a GAST pump, has an exhaust side, and an intake side. An exhaust line  312  and a vacuum line  314  extend from and lead to the intake and exhaust sides of the pump  310 , respectively. A probe  340  is connected to respective ends of these lines  312  and  314 . The probe  340  blows air onto an object  530  (or into a manufacturing environment) and sucks air from the object  530  (or environment).  
         [0066]     A filter  372  (referred to hereinafter as the second filter) for filtering air is installed in the exhaust line  312 . A first flow directional control valve  350 , an adsorption device  330 , and a second flow directional control valve  370  are disposed in series in the vacuum line  314 . The first flow directional control valve  350  is connected to a filter  352  (referred to hereinafter as the first filter).  
         [0067]     The vacuum line  314  is divided at the second flow directional control valve  370  into first and second branches  314   a  and  314   b . The adsorption device  330 , whose structure is the same as that of the adsorption chamber  190  of the first embodiment, is disposed in the vacuum line  314  downstream of the second flow directional control valve  370  with respect to the direction of flow of air through the vacuum line  314 . A particle counter  320  having a particle detector is connected to one end of the first branch  314   a  of the vacuum line  314 , and the probe  340  is connected to one end of the second branch  314   b  of the vacuum line  314 . A third flow directional control valve  360  is disposed in the  314   a  second branch  314   b  of the vacuum line  314 , and a filter  362  (referred to hereinafter as the third filter) is connected to the third flow directional control valve  360 . Each of the flow directional control valves  350 ,  360  and  370  is a 3-way solenoid valve. Additionally, a flow meter  380  can be connected to the vacuum line  314 .  
         [0068]     The particle counter  320  is electrically connected to the probe  340  through a cable  390 . Alternatively, the electrical connection between the particle counter  320  and the probe  340  can be a wireless connection. In either case, the probe  340  controls the operation of the particle counter  320 . For example, the particle counter  320  is turned on by the probe  340  when the probe  340  is operating, i.e., while air is flowing through the probe. Likewise, the particle counter  320  is turned off when the probe  340  stops operating. Also, the particle counter  320  can have a built-in pump (not shown) to induce air into the particle detector from the first branch  314   a  of the vacuum line  314 . The particle counter  320  is conventional, per se.  
         [0069]     The particle sampling apparatus  300  can be operated in a particle detection mode or a particle adsorption mode. In the particle detection mode, the particle counter  320  is used. In the particle adsorption mode, the adsorption chamber  330  is used. The particle detection mode will be described below in detail with reference to  FIGS. 14 and 15 , and the particle adsorption mode will be described below in detail with reference to  FIGS. 16 and 17 .  
         [0070]     Referring to  FIG. 14 , in the particle detection mode, the first directional flow control valve  350  is set to a first position “         ”. Air flows from the first filter  352  to the pump  310  when the valve  350  is in the first position “         ”. The second directional flow control valve  370  is set to a first position “         ” that allows air sucked by the probe  340  into the second branch  314   b  of the vacuum line  314  to flow into the first branch  314   a  of the vacuum line  314 . The third exchange valve  360  is set to a first position “↑” that allows air introduced into the first branch  314   a  of the vacuum line  314  to flow into the particle counter  320 .  
         [0071]     Referring to  FIG. 15 , the pump  310  and the particle counter  320  begin operating (S 310  and S 300 ) when power is supplied to the sampling apparatus  300 . As a result, air is sucked through the first filter  352  by the vacuum created by the pump  310  and is thus filtered by the first filter  352  (S 380 ). The filtered air is introduced to the pump  310  through the vacuum line  314  by the first exchange valve  350  set at the first position “         ” (S 390 ). Air that has been introduced to the pump  310  is forced to the probe  340  through the exhaust line  312  by the pump  310 . The air is filtered and purified by the second filter  372  (S 320 ). The purified air is blown out of the probe  340  and, at the same time, air is sucked into the probe  340  (S 330 ). The air issuing from the probe  340  may be directed onto a surface of the object  530  to dislodge particles from the surface and, in this case, air containing the particles is sucked into the probe  340  (S 330 ). Alternatively, the air may be simply blown out of the probe  340 , and air containing particles suspended in the environment in which the probe is located is sucked into the probe  340 .  
         [0072]     The integral pump of the particle counter  320  also acts (S 360 ) to draw air through the probe  340  (S 330 ). Air flowing from the probe  340  into the second branch  314   b  of the vacuum line is directed into the first branch  314   a  by the second flow directional control valve  370  (S 340 ). The air introduced into the first branch  314   a  of the vacuum line  314  is directed to the particle counter  320  by the third flow directional control valve  360  (S 350 ). The particle counter  320  detects particles contained in the air, determines the size of the particles, and counts the number of particles of each size (S 370 ).  
         [0073]     Referring to  FIG. 16 , the first flow directional control valve  350  is set to a second position “↑”, the second flow directional control valve  370  is set to a second position “←”, and the third flow directional control valve  360  is set to a second position “         ” to place the sampling apparatus  300  in the particle adsorption mode. The paths along which air is confined to flow in the sampling apparatus  300  when the flow directional control valves  350 ,  360  and  370  are at their respective positions correspond to the symbols above in  FIG. 16 .  
         [0074]     Referring to  FIG. 17 , power is supplied to the pump  310  (S 490 ). As a result, air is forced through the exhaust line  312  and is purified by the second filter  372  (S 420 ). The purified air is blown out through the probe  340 , and air containing particles is sucked into the probe  340  (S 430 ). The air containing particles is directed (S 540 ) from the second branch  314 b of the vacuum line  314  to the adsorption chamber  330  by the second exchange valve  370 . The particles are trapped inside the chamber of the adsorption device  330 , and the air that has passed through the chamber is directed (S 480 ) to the pump  310  by the first flow directional control valve  350 . Also, the air may be directed through flow meter  380  (S 460 ) before it flows into the pump  310 . In this case, the flow rate discerned by the flow meter  380  may be used to control the speed of the pump  310 , i.e., regulate the flow rate of air in the sampling apparatus  300 . In any case, the air fed to the pump  310  is pumped into the exhaust line  312 , is purified in the exhaust line  312  by the second filter  372  (S 420 ) and is blown out through the probe  340  (S 430 ).  
         [0075]     The particle counter  320  may also be operated at this time (S 400 ) by turning on (S 500 ) the pump of the particle counter  320 . Thus, air is induced through the third filter  362  by the vacuum created by the particle counter  320 , such that the air is purified by the third filter  362  (S 510 ). The purified air is directed to the particle counter  320  by the third flow directional control valve  360  (S 520 ).  
         [0076]     As described above, the present invention determines not only the number of particles of each size, but also can collect the particles so that the particles can be examined to determine their shape and/or composition. Therefore, the present invention can be used to trace the particles to their source.  
         [0077]     Finally, although the present invention has been described in connection with the preferred embodiments thereof, it is to be understood that the scope of the present invention is not so limited. On the contrary, various modifications of and changes to the preferred embodiments will be apparent to those of ordinary skill in the art. Thus, changes to and modifications of the preferred embodiments may fall within the true spirit and scope of the invention as defined by the appended claims.

Technology Classification (CPC): 6