JP2001133387A - Ultra-fine particle classifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhaust a sealing gas, efficiently at a high exhausting speed, in a differential-type electricity mobility classifying device in order to operate the classifying device at a pressure lower than the atmospheric pressure. SOLUTION: This differential-type electricity mobility classifying device has dimensions reduced by changing the shape of the device from a double cylinder type to a rectangular type for improvement. This enables the sealing gas in this device to be exhausted efficiently at a high exhausting speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrafine particle classifier, and more particularly, to a differential electric mobility classifier utilizing electric mobility depending on the particle size of charged particles in an electrostatic field.

[0002]

2. Description of the Related Art Conventionally, a differential type electric mobility classifier, which is an ultrafine particle classifier utilizing electric mobility depending on a particle diameter of a charged particle in an electrostatic field, has been capable of producing submicron ultrafine particles with high efficiency. It has been used for performance tests of high-performance air filters that collect and separate, generation of standard aerosols and monitoring of the particle size of ultrafine particles in monitoring the purification atmosphere.

FIG. 4 shows, for example, Aerosol Research Vol.
2, No. 2, p106 (1987) or Journal of the Society of Powder Technology, Vol. 21, No. 12, p753 (1984)
, A conventional differential mobility classifier 400
FIG.

In FIG. 4, charged ultrafine particles 401
Is transported by the carrier gas 402, flows in from the upper end of the double cylindrical classifier, and flows inside the sheath gas 40.
3. Merge with clean air that is 3. Charged ultrafine particles 40
The mixed gas of 1 and the sheath gas 403 flows through the double cylindrical portion as a laminar flow. In this double cylindrical portion, an electrostatic field is applied by the DC power supply 404 in a direction perpendicular to the flow direction of the mixed gas. Therefore, the charged ultrafine particles 401 draw a trajectory corresponding to each electric mobility. Since the electric mobility depends on the particle diameter of the ultrafine particles 401, only the ultrafine particles 401 having a specific particle diameter reach the lower slit 405, are classified, and are taken out from the carrier gas exhaust port 406. The ultrafine particles having other particle diameters are exhausted from the sheath gas exhaust port 407 together with the sheath gas, or move and adhere to the inner collecting electrode 408.

[0005]

When ultrafine particles having a particle size of several nm to several tens of nm are produced by pulse laser deposition in a rare gas, the atmospheric gas pressure is usually several Torr.
To several hundred Torr. Therefore, in order to transport and classify the ultrafine particles generated by the pulse laser deposition method in a rare gas using a differential pressure, the differential electric mobility classifier needs to operate at a pressure lower than the atmospheric gas pressure. Here, in the case of the conventional double-cylindrical classifier shown in FIG. 21, No. 12, p753
(1984) is L = 400 mm,
Since R ₁ = 15 mm and R ₂ = 25 mm, the capacity of the sheath gas flowing through the double cylindrical classifier is large, and a large amount of clean air is required as the sheath gas. Therefore, in order to operate the conventional double-cylindrical classifier at a pressure lower than the atmospheric gas pressure, a large-sized vacuum pump having a high pumping speed is required.

[0006] Further, by operating the double cylindrical classifier, it is necessary to actually classify and detect the ultrafine particles (including the charging unit, the ultrafine particle classification unit, the detection unit, the vacuum pump, etc.). The overall size of the particle classification and detection device becomes large. As a result, whether or not the ultrafine particle classification detection device can be attached depends on the shape and size of the ultrafine particle generation device.

[0007] Ultra-fine particles transported by the carrier gas may have a long transport time (long transport distance).
Agglomeration occurs during transportation. Therefore, it is necessary to reduce the influence of the aggregation in order to classify and detect the generated ultrafine particles with a differential type electromobility classifier while maintaining the particle size and shape.

[0008] The present invention has been made in view of the above point, and in order to operate the differential-type electric mobility classifier at a pressure lower than the atmospheric pressure, the sheath gas in the differential-type electric mobility classifier is efficiently used. The purpose is to exhaust at a high exhaust speed.

[0009]

SUMMARY OF THE INVENTION The present invention improves the shape of a differential type electric mobility classifier from a double cylindrical type to a rectangular type.
The size of the differential electric mobility classifier was reduced. Thereby, the sheath gas in the differential electric mobility classifier can be efficiently evacuated at a high evacuation speed. As a result, the differential electric mobility classifier can be operated at a pressure lower than the atmospheric pressure.

Further, the present invention reduces the sheath gas capacity in the differential type electric mobility classifier and improves the exhaust efficiency of sheath gas (the ratio of the exhaust capacity to the sheath gas inflow capacity).

Further, the present invention reduces the size of the differential electric mobility classifier and improves the exhaust efficiency of the sheath gas, so that the differential electric mobility classifier using a vacuum pump having a smaller displacement (ie, a smaller size) can be obtained. The low pressure operation of the degree classifier was enabled. As a result, the entire ultra-fine particle classification and detection device including the charging unit, ultra-fine particle classification unit, detection unit, vacuum pump, etc. can be miniaturized and can be attached to any type of ultra-fine particle generation device. A highly efficient ultrafine particle classifier has been realized.

[0012] Further, by miniaturizing the ultra-fine particle classification and detection device, it is possible to shorten the transport time (transport distance) of the ultra-fine particles required from taking-in to classification and detection. Can be reduced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An ultrafine particle classifier according to a first embodiment of the present invention is installed substantially parallel to a sheath gas flow path which flows linearly as a laminar flow, and introduces charged ultrafine particles into a viscous fluid. Classification was performed using electric mobility depending on the particle size of charged particles when an electrostatic field was applied, and a classification region having a substantially rectangular cross section along the sheath gas flow path was provided.

With this configuration, it is possible to classify the ultrafine particles in the classification region having a substantially rectangular cross section. Thus, the sheath gas capacity in the classification region can be reduced, and the exhaust efficiency of the sheath gas (the ratio of the exhaust capacity to the sheath gas inflow capacity) can be improved. As a result, low-pressure operation of the ultrafine particle classification device with a small displacement (that is, smaller) vacuum pump has become possible.

According to a second aspect of the present invention, there is provided the ultrafine particle classification apparatus according to the first aspect, wherein the ultrafine particles are installed substantially parallel to the sheath gas flow path and are used to eject charged ultrafine particles to the classification area. A first plane portion having a substantially rectangular shape having a fine particle ejection mechanism, and the first plane portion sandwiching the classification region;
A second flat portion having a substantially rectangular shape, having an ultrafine particle sorting mechanism for sorting ultrafine particles having a uniform particle size classified in the classification region, arranged in parallel with the flat portion of The ultrafine particle classification region is formed by being sandwiched between the first plane portion and the second plane portion.

In the conventional double-cylinder type differential mobility classifier, in order to classify ultrafine particles having a single particle size, it is necessary to form an isotropic flow in the radial direction of the cylinder. For this reason, a structure capable of exhausting the sheath gas in multiple directions from the ultrafine particle classifier is required. In order to realize this structure, the external dimensions of the device become large. However, according to the configuration shown in the second embodiment of the present invention, it is not necessary to exhaust gas in multiple directions, and therefore, it is possible to reduce the outer dimensions of the ultrafine particle classification device.

According to a third aspect of the present invention, in the ultrafine particle classification device according to the first aspect or the second aspect, the cross-sectional area of the classification area is the cross-sectional area of a sheath gas pipe connected to the sheath gas inlet. Has been made equal or larger.

As described above, by reducing the cross-sectional area of the classification region to the same as the cross-sectional area of the pipe upstream of the sheath gas inlet, the sheath gas volume in the ultrafine particle classification region is reduced, and a vacuum pump installed downstream of the sheath gas exhaust port Effective pumping speed and pumping capacity can be reduced. Also,
When the cross-sectional area of the classification region is made equal to the cross-sectional area of the pipe upstream of the sheath gas inlet, a sudden change in conductance before and after the sheath gas inlet can be prevented, and stagnation can be suppressed in the sheath gas flow. .

According to a fourth aspect of the present invention, in the ultrafine particle classification apparatus according to any one of the first to third aspects, the cross-sectional shape of the sheath gas pipe connected to the sheath gas inlet is the same as the classification area. It changes continuously to the cross-sectional shape.

According to this configuration, the abrupt change in the shape of the gas flow path before and after the sheath gas inlet is prevented, thereby suppressing the disturbance of the sheath gas flow and maintaining the laminar flow.

According to a fifth aspect of the present invention, in the ultrafine particle classification apparatus according to any one of the first to fourth aspects, four corners of the cross section of the classification area are chamfered in a circular shape.

By chamfering in this manner, the sheath gas flowing from the cylindrical pipe upstream of the sheath gas inlet is easily maintained in a laminar flow in the rectangular ultrafine particle classification region.

[0023] The ultrafine particle classification detecting apparatus according to a sixth aspect of the present invention comprises: a capturing section for capturing the ultrafine particles; a charging section for charging the captured ultrafine particles; The ultrafine particle classification device according to claim 1 for classification, a detection unit for measuring the concentration of the classified ultrafine particles or depositing the ultrafine particles on a substrate, and a sheath gas installed downstream of the ultrafine particle classification device and the detection unit. And a differential exhaust means for exhausting the carrier gas, and operates under atmospheric pressure.

According to this configuration, the ultrafine particles generated at a pressure equal to or lower than the atmospheric pressure are taken in by the intake section, ionized by the charging section, conveyed to the ultrafine particle classification apparatus by differential exhaust, classified, and then detected. Can be detected.

According to a seventh aspect of the present invention, in the ultrafine particle classification detecting device according to the sixth aspect, the operating pressure in the classification region of the ultrafine particle classification device is 50 Torr or less.

With this configuration, the ultrafine particles generated at a pressure of 50 Torr or less are taken in by the intake unit, ionized by the charging unit, transported to the ultrafine particle classifier by differential exhaust, classified, and then classified by the detection unit. It becomes possible to detect.

According to an eighth aspect of the present invention, in the ultrafine particle classification and detection apparatus according to the sixth or seventh aspect, the time required for ultrafine particles to be transported from the intake section to the detection section is 1 second. Within.

As described above, by shortening the transport time from the capture of the ultrafine particles to the detection thereof, the influence of the aggregation of the ultrafine particles in the transport process can be reduced.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, the ultrafine particle classification apparatus according to the above embodiment will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1A is a cross-sectional view of the ultrafine particle classification device according to the above-described embodiment as viewed from above, and FIG.
FIG. 2 is a schematic view of a cross-sectional view of the ultrafine particle classification device according to the embodiment as viewed from the side. The ultrafine particle classifier according to the above-described embodiment is an improved ultrafine particle classifier for operating at a pressure lower than the atmospheric pressure. In order to operate the ultrafine particle classifier at a pressure lower than atmospheric pressure,
It is necessary to efficiently exhaust the sheath gas in the ultrafine particle classifier at a high exhaust speed. In order to solve this problem, the inventors have improved the cross-sectional shape of the ultrafine particle classification device from a conventional double cylindrical type to a rectangular type.

The ultrafine particle classifier 101 has a rectangular cross-sectional shape and includes an outer shell 103 having a space 102 with a substantially rectangular cross-section inside. On both left and right inner side surfaces of the outer shell portion 103, a flat portion A104 and a flat portion B105 which are respectively installed in parallel at a predetermined interval R are formed. Each of the flat portion A104 and the flat portion B105 has a rectangular shape.

A carrier gas inlet 106 for carrying and introducing a carrier gas 117 containing charged ultrafine particles is provided on the plane portion A104 side of the outer shell portion 103 and slightly above the center. Further, in the vicinity of the carrier gas inlet 106 of the plane portion A104, a carrier gas outlet 1 as an ultrafine particle ejecting mechanism for ejecting the introduced carrier gas 117 containing charged ultrafine particles to the classification region 107 is provided.
08 is provided.

The classifying region 107 is composed of a space having a constant interval R sandwiched between the plane portions A104 and B105, a carrier gas outlet 108, and a slit 109 for selecting ultrafine particles having a uniform particle diameter.

A carrier gas exhaust port 110 for taking out ultra-fine particles selected to have a uniform particle size is provided on the outer side surface near the slit 109 of the outer shell portion 103.

A metal flat plate 111 is provided on the side surface of the outer shell 103 on the classification region 107 side. That is,
The side surface of the plane portion B105 on the classification region 107 side is formed of a metal flat plate 111. Further, on the outer side surface of the metal flat plate 111 with respect to the plane portion B105 of the outer shell portion 103,
An insulator 112 is provided. Thereby, the metal flat plate 111 is completely insulated by the insulator 112. The insulator 112 is provided so as to cover the inner portion of the outer shell 103 except for the plane portion B105 of the outer shell 103.

Further, a DC voltage power supply 113 is connected to the flat portion B105 side of the outer shell portion 103. The outside of the outer shell 103 is grounded by the DC voltage power supply 113. Further, the metal flat plate 111 has a DC voltage power supply 113.
A positive or negative voltage is applied.

Further, a sheath gas inlet 119 is provided upstream of the sheath gas flow path in the classification area 107.
Further, a sheath gas exhaust port 114 is provided downstream of the sheath gas flow path in the classification area 107. A filter 116 is provided downstream of the sheath gas inlet 119 and inside the outer shell 103 to make the sheath gas 115 introduced from the sheath gas inlet 119 uniform flow. A sheath gas pipe for introducing the sheath gas 115 into the sheath gas inlet 119 is provided upstream of the sheath gas inlet 119.

Next, the ultrafine particle classifier 101 shown in FIG.
In the above, ultrafine particles were classified by the following operation. The sheath gas 115 is introduced into the ultrafine particle classification device 101 through the sheath gas inlet 119, passes through the filter 116, passes through the classification region 107 in a laminar flow state, and is exhausted through the sheath gas exhaust port 114. On the other hand, the charged ultrafine particles are transported by the carrier gas 117, introduced into the ultrafine particle classification device 101 through the carrier gas inlet 106, and ejected from the carrier gas outlet 108 into the classification region 107.

The classifying region 107 includes a flat portion A104
Since an electrostatic field is applied in a direction perpendicular to the sheath gas flow by the DC voltage power supply 113 between the flat portion B105 and the flat portion B105, the ultrafine particles ejected from the carrier gas ejection port 108 are transported downward by the sheath gas 115, It is deflected in the direction from the plane portion A104 to the plane portion B105 while drawing a trajectory corresponding to the electric mobility depending on the number of charges and the particle size. In the bent ultrafine particles, the flat portion B1
Only those that have reached the slit 109 provided at the lower portion of the fuel cell 05 are extracted from the carrier gas exhaust port 110 as classified ultrafine particles.

In order to improve the classification resolution in the ultrafine particle classification apparatus 101 shown in FIG.
Is required to be in a laminar flow state. In order to realize this laminar flow state, it is desirable that the cross-sectional shape of the classification area 107 has a smooth curve as much as possible, avoiding an acute shape in which stagnation is likely to occur. Therefore, the four corners 118a to 118d of the cross section of the classification region 107 of the rectangular ultrafine particle classification device 101 are chamfered in a circular shape. As a result, a more uniform laminar flow state of the sheath gas 115 can be created, and the resolution of the ultrafine particle classification device 101 for classification of ultrafine particles can be improved.

In general, the exhaust conductance of a pipe in the viscous flow region is proportional to the square of the cross-sectional area of the pipe. Therefore, the conductance of the classification region 107 of the ultrafine particle classification device 101 is increased by making the cross-sectional area of the classification region 107 of the ultrafine particle classification device 101 equal to or larger than the cross-sectional area of the sheath gas pipe upstream of the sheath gas inlet 119. ,
The conductance of the sheath gas pipe upstream of the sheath gas inlet 119 was equal to or larger than the conductance. Thus, the sheath gas 115 flowing from the sheath gas pipe into the classification area 107 through the sheath gas inlet 119 is eliminated, and the laminar flow of the sheath gas 115 passing through the classification area 107 is enabled.

Further, the shape of the cross section of the sheath gas pipe upstream of the sheath gas inlet 119 is continuously changed to the shape of the cross section of the classification region 107 of the ultrafine particle classifier 101, so that a sharp sheath gas flow path around the sheath gas inlet 119 is obtained. By preventing the change in shape, stagnation and turbulence of the sheath gas flow are suppressed, and the sheath gas 115 passing through the classification region 107 can be in a laminar flow state. That is, it is possible to realize the ultrafine particle classification device 101 having good classification performance.

In particular, when the cross-sectional area of the classification region 107 of the ultrafine particle classifier 101 is substantially the same as the cross-sectional area of the sheath gas pipe upstream of the sheath gas inlet 119, a smooth and continuous flow around the sheath gas inlet 119 is obtained. The change in the sheath gas flow path shape is extremely effective in maintaining the laminar flow of the sheath gas flow.

FIG. 2 is a configuration diagram of an ultrafine particle classification detecting apparatus according to an embodiment of the present invention. With the ultrafine particle classification detecting device according to the above-described embodiment, the generated ultrafine particles can be charged, classified using the ultrafine particle classification device 101 shown in FIG. 1, and detected.

First, the overall configuration of the ultrafine particle classification detecting device 200 will be described. Ultrafine particle classification detector 200
Is a capturing unit 201 for capturing the generated ultrafine particles.
A charging unit 202 for ionizing the ultrafine particles captured by the capturing unit 201, a classifying unit 203 for classifying the ultrafine particles charged by the charging unit 202, and a single particle size by the classifying unit 203. A detection unit 204 for depositing the classified ultrafine particles on the substrate and measuring the particle size.

The intake unit 201 and the classifying unit 203 are connected by an ultrafine particle transport tube 205, and the charging unit 202 is installed in the middle of the ultrafine particle transport tube 205. The classification unit 203 and the detection unit 204 are connected to the ultrafine particle transport pipe 206 after classification.
Are connected by

Next, the configuration of each part of the ultrafine particle classification detecting device 200 will be described. First, the capturing unit 201 will be described. The intake unit 201 is provided with an ultrafine particle generation chamber 207. The ultrafine particle generation chamber 207 has a vacuum evacuation system 208 for reducing the pressure inside the ultrafine particle generation chamber 207.
, An ultrafine particle transport tube 205, and an introduction window 209. Through the introduction window 209, a pulsed laser beam emitted from the light source can be introduced toward a solid target (not shown) installed in the ultrafine particle generation chamber 207. The ultrafine particles released from the solid target are sent to the charging unit 202 via the ultrafine particle transport pipe 205. One end of the ultrafine particle transport tube 205 is connected to the ultrafine particle generation chamber 2
07, near the solid target installation portion.
At the tip of the ultrafine particle transport tube 205, an ultrafine particle intake port (not shown) is provided. The ultrafine particle inlet collects the ultrafine particles generated in the ultrafine particle generation chamber 207.

As a vacuum evacuation system 208, a turbo molecular pump 210 is connected to the ultrafine particle generation chamber 207. Further, a rotary pump 211 is connected to the turbo molecular pump 210.

A dry pump 212 is connected to the ultrafine particle generation chamber 207. Dry pump 212
When the atmospheric rare gas is introduced into the ultrafine particle generation chamber 207, the rare gas is differentially evacuated to set a constant atmospheric rare gas pressure. Further, the ultrafine particle generation chamber 207
Is connected to a mass flow controller 213. The mass flow controller 213 controls the flow rate of the atmospheric rare gas introduced into the ultrafine particle generation chamber 207.

Next, the charging section 202 will be described. The ultrafine particle transport tube 205 is provided with a charging unit 202 for ionizing ultrafine particles. Americium Am, which is one of the radioisotopes, is provided inside the charging unit 202. Thereby, the ultrafine particles passing through the charging unit 202 are charged. Further, by charging the ultrafine particles with a high-density ultraviolet light source such as ArF excimer laser light (wavelength 193 nm) in the charging unit 202, the ultrafine particles can be monopolarly charged with high efficiency. Thereby, the yield of the ultrafine particles to be classified can be improved. In this embodiment, A
Although an rF excimer laser beam was used, an excimer lamp or vacuum ultraviolet (Deep Ultra Vi
olet (DUV) lamps can also be used.

Next, the classification section 203 will be described. The ultrafine particle classification device 101 is installed at a position of the classification unit 203 connected to the charging unit 202. Ultrafine particle classifier 10
Reference numeral 1 denotes a rectangular type ultrafine particle classification device 101 shown in FIG. The ultrafine particle classification device 101 is provided with a mass flow controller 214. The mass flow controller 214 controls the flow rate of the sheath gas 115 introduced into the ultrafine particle classification device 101, which is indispensable when classifying ultrafine particles.

The mass flow controller 214 is connected to a sheath gas transfer pipe for transferring the sheath gas 115 into the ultrafine particle classification device 101. A sheath gas differential exhaust system 215 for exhausting the sheath gas 115 inside the ultrafine particle classifier 101 is provided at the bottom of the ultrafine particle classifier 101. In addition, the ultrafine particle classifier 1
A post-classified ultrafine particle transport pipe 206 for transporting the carrier gas 117 containing ultrafine particles classified into a single particle size at 01 to the detection unit 204 and jetting the same into the detection unit 204 is provided.

Finally, the detection unit 204 will be described. The detection unit 204 is provided with a deposition chamber 216 for depositing the classified ultrafine particles. In addition, the deposition chamber 216
Is connected to the ultrafine particle classification device 101 via the ultrafine particle transport pipe 206 after classification. Further, the deposition chamber 216 is provided with a carrier gas differential exhaust system 217 for performing differential exhaust of the carrier gas 117 so that the deposition chamber 216 is maintained at a constant pressure.

When the charged ultrafine particles classified by the ultrafine particle classifying apparatus 101 are deposited on a deposition substrate (not shown), the charged electrons generated between the ultrafine particles and the substrate are deposited in the deposition chamber 216. Ammeter 218 is provided to measure the transfer (current) of the current.

In the ultrafine particle classification detecting apparatus 200 shown in FIG. 2, generation, take-in, charging, classification, and detection of ultrafine particles were performed by the following operations.

First, a solid target is placed in the ultra-fine particle generation chamber 207, and then the inside of the ultra-fine particle generation chamber 207 is depressurized by the vacuum exhaust system 208, and then an atmosphere rare gas is introduced through the mass flow controller 213. Next, the atmospheric rare gas is differentially evacuated by the dry pump 212 to set a constant atmospheric rare gas pressure. Next, in this state, a pulsed laser beam emitted from a light source outside the ultrafine particle generation chamber 207 is introduced into the ultrafine particle generation chamber 207 through the introduction window 209, and the solid target is irradiated with the pulsed laser beam. Atoms, ions, and clusters are emitted from the surface of the solid target excited by irradiating the solid target with the pulsed laser.
They repeatedly associate and fuse with rare gas molecules (atoms) in the atmosphere, and grow into ultrafine particles in the gas phase.
The ultrafine particles at this stage have a particle size distribution. The generated ultra-fine particles are collected from the ultra-fine particle inlet of the ultra-fine particle transport tube 205 and are subjected to differential evacuation.
5 to the charging unit 202.

The ultrafine particles charged by passing through the charging unit 202 are transported to the ultrafine particle classification device 101 through the ultrafine particle transport tube 205.

The ultrafine particles conveyed to the ultrafine particle classifier 101 are classified into a single particle size, and after classification by the carrier gas 117, are conveyed to the deposition chamber 216 by differential exhaust through the ultrafine particle conveying pipe 206.

A deposition substrate (not shown) is installed inside the deposition chamber 216. The ultrafine particles classified to a single particle size and transported from the ultrafine particle classification device 101 through the ultrafine particle transport tube 206 after classification are: It is deposited on the deposition substrate. The ultrafine particles deposited on the deposition substrate are evaluated for particle diameter and shape by observation with an electron microscope and optical measurement. Also,
By the minute ammeter 218 installed in the deposition chamber 216,
The particle concentration of the ultrafine particles is measured.

In order to operate the ultrafine particle classification device 101 shown in FIG.
5 must be evacuated at a high evacuation rate. Or,
The sheath gas 115 must be efficiently evacuated by the sheath gas differential evacuation system 215 constituted by a vacuum pump having a limited evacuation speed. In the present invention, the cross-sectional area of the classification region 107 is made to be substantially the same as the cross-sectional area of the piping upstream of the sheath gas inlet by improving the shape of the conventional dual-cylindrical differential mobility classifier to a rectangular shape. An ultrafine particle classification device 101 that can be reduced to as small as possible has been realized. Thereby, the sheath gas capacity in the ultrafine particle classification device 101 can be significantly reduced, and the sheath gas 115 is efficiently exhausted by the sheath gas differential evacuation system 215 composed of a small vacuum pump. Low pressure operation was realized.

More specifically, for example, a sheath gas pipe upstream of the sheath gas inlet 119 shown in FIG.
Using a 5-inch (about 12.7 mm) cylindrical pipe, the cross-sectional area of the classification area 107 of the ultrafine particle classifier 101 was reduced to about the same as the cross-sectional area of the sheath gas cylindrical pipe (about 130 mm ² ). Carrier gas outlet 108 and slit 1
The projection distance L of 09 was 20 mm. As a result, the sheath gas capacity in the ultrafine particle classifier 101 was reduced to about 200 times that of the conventional differential mobility classifier shown in FIG. As a result, even when a small vacuum pump of 130 l / min is used as the vacuum pump constituting the sheath gas differential pumping system 215 and the carrier gas differential pumping system 217, 20 to 20 micrometer is detected by the ultrafine particle classification detecting apparatus 200 shown in FIG. 5
A low pressure operation of 0 Torr has become possible. Further, the cross-sectional shape of the classification region 107 of the ultrafine particle classification device 101 has a shape in which four corners 118a to 118d of a rectangle are chamfered into a circle,
From the circular cross section of the sheath gas cylindrical pipe, the classification area 1
The cross section was continuously changed to a cross section of 07 to prevent a sudden change in the shape of the gas flow path before and after the sheath gas inlet, thereby suppressing the disturbance of the sheath gas flow and maintaining the laminar flow.

The ultrafine particles captured by the ultrafine particle classification detecting device 200 by the capturing unit 201 shown in FIG.
A transport time depending on the flow rates of the carrier gas 117 and the sheath gas 115 is required until the detection is performed at 04. Generally, in ultrafine particles suspended in a gas, the ultrafine particles associate and aggregate under the influence of Brownian diffusion, and the particle diameter of the ultrafine particles increases with time. Further, with the aggregation, the number concentration of the ultrafine particles suspended in the gas decreases with time. Basically, in the case of ultrafine particles having a uniform initial particle size, the number concentration decreases in inverse proportion to time. Further, when the initial number concentration of the ultrafine particles floating in the gas is high, the ratio of the ultrafine particles aggregating with each other also increases. As a result, the dependence of the number concentration on the time and the initial number concentration is expressed as the difference between the reciprocal of the initial number concentration and the reciprocal of the number concentration at that time is proportional to time. Therefore, if the transport time is long, the influence of the aggregation of the ultrafine particles cannot be ignored. In order to reduce the influence of the aggregation, the transfer time is shortened (that is, the flow rate of the carrier gas 117 and the sheath gas 115 is increased, or
It is conceivable either to shorten the distance from to the detection unit 204) or to reduce the initial number concentration of the ultrafine particles. Among these, the initial number concentration of the ultrafine particles also depends on the method of producing the ultrafine particles. Therefore, in the ultrafine particle classification detecting device 200, the ultrafine particle classification device 101 is downsized, and the vacuum pumps constituting the sheath gas differential exhaust system 215 and the carrier gas differential exhaust system 217 are also small, and the intake unit 201 is used. It is most effective to shorten the distance from to the detection unit 204.

FIG. 3 shows an initial particle diameter of 10 n suspended in a gas.
5 shows the time dependency of the number concentration in the ultrafine particles of m. From FIG. 3, it for example the initial number concentration of ultrafine particles of an initial particle size 10nm 10 ^{1 2} / m ³ in the following cases, the time required for the initial number concentration is halved is about 1.0sec or more Understand. That is, from the capturing unit 201 to the detecting unit 204
When the time required for the ultrafine particles to be transported is within 1.0 second, it is possible to suppress the number concentration of the ultrafine particles from decreasing to half, and to considerably suppress the influence of the aggregation of the ultrafine particles. It can be said that it is possible.

Specifically, in the ultrafine particle classification detecting device 200 shown in FIG.
The transport path to the pipe was 0.5 inches in diameter, and the transport distance from the intake unit 201 to the detection unit 204 was 50 cm. Further, the flow rate of the carrier gas 117 is set to 1 SLM (0
1 ° C. and 1 atm). Under these conditions, the operating pressure of the ultrafine particle classifier 101 is about 50 To
rr (that is, when the pressure in the carrier gas piping is about 50
The transfer speed of the ultrafine particles at Torr) is about 2.2 m / s
ec, and the time required for transport is estimated to be about 0.23 sec. When the operation pressure of the ultrafine particle classification device 101 is 20 to 50 Torr in the ultrafine particle classification detection device 200 in which the time required for transporting the ultrafine particles from the intake unit 201 to the detection unit 204 is within 1.0 second. And ultrafine particles having a particle diameter of 10 nm were classified and detected.

As described above, according to the above embodiment, the sheath gas 115 in the ultrafine particle classification device 101 can be efficiently exhausted at a high exhaust speed. As a result, the ultrafine particle classification device 101 can be operated at a pressure lower than the atmospheric pressure. Further, the sheath gas capacity of the ultrafine particle classification device 101 was reduced, and the exhaust efficiency of the sheath gas 115 (the ratio of the exhaust capacity to the sheath gas inflow capacity) was improved. Furthermore, the ultrafine particle classifier 101 is downsized, and the sheath gas 1
By improving the exhaust efficiency of No. 15, the ultra-fine particle classification device 101 can be operated at a low pressure by a vacuum pump having a smaller exhaust amount (that is, a smaller size).

Further, according to the above-described embodiment, by miniaturizing the entire ultrafine particle classification and detection device 200, the ultrafine particle classification device 200 is easy to carry and can be easily attached to any type of ultrafine particle generation device. A classification detection device 200 can be provided.

In the above embodiment, the carrier gas 1
By shortening the transport time of the ultrafine particles transported by 17, the aggregation of the ultrafine particles during the transport can be suppressed. This allows the ultrafine particles to be classified and detected by the ultrafine particle classification device 101 while maintaining the particle diameter and shape of the generated ultrafine particles.

[0068]

As described above, according to the present invention,
The sheath gas in the differential mobility classifier can be efficiently
Since the gas can be evacuated at a high evacuation speed, the differential electric mobility classifier can be operated at a pressure lower than the atmospheric pressure.

Further, according to the present invention, it is possible to produce an ultrafine particle classification detecting device which can be operated in a pressure range below the atmospheric pressure with a small vacuum pump and which can be downsized so that the whole device can be carried. Become.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of an ultrafine particle classification device according to an embodiment of the present invention as viewed from above. FIG. 1B is a cross-sectional view of an ultrafine particle classification device according to an embodiment of the present invention as viewed from the side.

FIG. 2 is a diagram showing a configuration of an ultrafine particle classification detecting apparatus according to the embodiment.

FIG. 3 is a diagram showing the time dependence of the number concentration of ultrafine particles having an initial particle diameter of 10 nm suspended in a gas.

FIG. 4 is a diagram showing a configuration of a conventional differential mobility classifier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Ultrafine particle classifier 103 Outer shell part 104 Plane part A 105 Plane part B 106 Carrier gas inlet 107 Classification area 108 Carrier gas outlet 109 Slit 110 Carrier gas exhaust 111 Metal plate 112 Insulator 113 DC voltage power supply 114 Sheath gas exhaust Mouth 116 Filter 200 Ultrafine particle classification detection device 201 Intake unit 202 Charging unit 203 Classification unit 204 Detection unit 205 Ultrafine particle transport tube 206 Ultrafine particle transport tube after classification 207 Ultrafine particle generation chamber 208 Vacuum exhaust system 214 Mass flow controller 215 Sheath gas differential Exhaust system 216 Deposition chamber 217 Carrier gas differential exhaust system 218 Micro ammeter

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Taketo Yoshida 3-1-1, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa Prefecture Inside Matsushita Giken Co., Ltd. (72) Yuka Yamada 3-chome, Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa No. 10 No. 1 Matsushita Giken Co., Ltd. F term (reference) 4D054 GA02 GA10 GB06 GB09

Claims (8)

[Claims] 1. An electric device which is installed substantially parallel to a sheath gas flow path which flows linearly as a laminar flow, and which depends on the particle diameter of charged particles when an electrostatic field is applied to a charged ultrafine particle in a viscous fluid. An ultrafine particle classification device, wherein the classification is performed using mobility, and a classification region having a substantially rectangular cross section along the sheath gas flow path is provided. 2. A first flat portion, which is installed substantially parallel to the sheath gas flow path, has an ultrafine particle ejection mechanism for ejecting charged ultrafine particles to the classification region, and has a substantially rectangular shape. An ultrafine particle sorting mechanism arranged in parallel with the first plane portion with the classification region interposed therebetween, for selecting ultrafine particles having a uniform particle size classified in the classification region, and having a substantially rectangular shape. A second flat portion, wherein the ultrafine particle classification region is formed by being sandwiched between the first flat portion and the second flat portion. 2. The ultrafine particle classification device according to 1.). 3. The ultrafine particle according to claim 1, wherein a cross-sectional area of the classification region is equal to or larger than a cross-sectional area of a sheath gas pipe connected to the sheath gas inlet. Classifier. 4. The sectional shape of a sheath gas pipe connected to the sheath gas inlet is continuously changed to the sectional shape of the classification region. The ultrafine particle classification device according to any one of the above. 5. The ultrafine particle classification apparatus according to claim 1, wherein four corners of the cross section of the classification area are chamfered in a circular shape. 6. An ultrafine particle classification apparatus according to claim 1, wherein an intake section for capturing the ultrafine particles, a charging section for charging the captured ultrafine particles, and a classifying apparatus for classifying the charged ultrafine particles. And a detection unit for measuring the concentration of the classified ultrafine particles and depositing the ultrafine particles on the substrate, and a differential exhaust unit for exhausting the sheath gas and the carrier gas installed downstream of the ultrafine particle classification device and the detection unit. An ultrafine particle classification detection device which is configured and operates at a pressure lower than the atmospheric pressure. 7. The ultrafine particle classification detecting device according to claim 6, wherein the operating pressure in the classification region of the ultrafine particle classification device is 50 Torr or less. 8. The ultrafine particle classification and detection device according to claim 6, wherein the time required for ultrafine particles to be transported from the intake section to the detection section is within one second. .