JP5650609B2 - Charge amount identification device for charged particles - Google Patents

Description

  The present invention relates to a charged particle amount specifying device for taking in charged particles floating in the air and specifying the charge amount.

  It is known that a Coulomb force acts on charged particles formed by charging particles in an electric field, and the charged particles easily adhere to an electric field generating source. Examples of the electric field generation source include various electrostatically charged members. In particular, the adhesion of particles due to the electrostatic charge is the following production facility, that is, a process of manufacturing a transparent electrode as an FPD material (flat panel display), In production facilities such as facilities for assembling / manufacturing production equipment and facilities for producing next-generation secondary batteries, there is a problem as particle contamination.

  Products (workpieces) manufactured at the above facilities allow manufacturing with a low cleanliness (cleanness: about 1000 to 10,000), but in the various production facility spaces described above, friction, peeling, cleaning, drying, etc. There are also large particles having a size of several μm that can be generated in the manufacturing process, and the adhesion to the product is one of the main factors for the decrease in the product yield.

  In addition, a conductive material is generally applied to the interior member of the clean room, but this is charged with a potential of about ± 100 V, which generates charged particles in the room space and adheres to the product. The degree of cleanliness will be reduced.

  By the way, the behavior of particles is affected by end sedimentation due to gravity, airflow, and Coulomb force, and the adsorption of charged particles to a work or interior member is mainly related to the Coulomb force, and the charged amount of charged particles ( The adsorptive power is determined by the electric field intensity generated by the charge amount) and the surface potential of the workpiece. For this reason, as a countermeasure against static electricity, the work surface is neutralized with an ionizer or soft X-rays.

  However, in current clean rooms and the like, since the charge amount of particles that can be generated due to static electricity distribution, friction, separation, etc. in the space has not been grasped, the above-described potential removal measures are actually effective. It's hard to say. Among them, although the generation mechanism of charged particles, their properties, and the charge amount are important elements for static elimination measures, a method for measuring or identifying particles having a size of several μm in an actual environment has not yet been established.

  A method of using a differential electrostatic classifier (DMA: Differential Mobility Analyzer) is currently used for measuring and specifying the charge amount of the charged particles.

  This method using DMA is an effective measurement method for particle classification under normal temperature and normal pressure, and its device configuration is a double concentric cylinder, applying voltage to the inner cylinder and grounding the outer cylinder Thus, a potential difference is provided between these cylinders, and the distance and potential between the inner and outer cylinders are kept constant, and the electric field is designed to be uniform. Clean air is introduced between the inner and outer cylinders in a laminar flow state (sheath airflow), while sample air containing charged particles is allowed to flow along the wall of the outer cylinder. In this DMA, the Coulomb force generated between the electric field that depends on the potential difference and the charged amount (charge amount) of the charged particles acts on the charged particles, and is drawn to the center electrode at a moving speed that has an electric mobility corresponding to the potential difference. Will be.

  Here, particles with higher electric mobility have a higher moving speed, and as a result, they tend to deposit on the upper part of the center electrode. On the other hand, particles with lower electric mobility flow out of the DMA together with the sheath airflow without being collected by the center electrode. easy. Note that a slit is provided below the center electrode, and only charged particles smaller than a certain electric mobility are taken out. In addition, by measuring the concentration using a condensation nucleus counter (CNC) or the like, the distribution of electric mobility can be obtained.

  As described above, the DMA has a mechanism that allows particles to be taken out from the slit as classified particles when the particle diameter and electric mobility (that is, the number of charges) coincide with the set airflow and Coulomb force. Therefore, as the particle diameter increases, the moving speed due to gravity and air current acting downward increases, and the length of the DMA naturally becomes longer. In addition, if the moving speed is low and the number of charges is small, it is necessary to apply a strong electric field to classify the particles with the slit, but the distance between the electrode (inner cylinder) and ground (outer cylinder) If is small, the cross-sectional dimension of the DMA must be increased to avoid the risk of discharge.

  In addition, according to the verification by the present inventors, in an experiment using a DMA having an outer cylinder diameter of 10 cm and a length of 30 cm, a particle size of 0.5 μm and a charge number of ± 6 are the maximum measurable sizes, Larger particle sizes are almost impossible to measure.

  On the other hand, in the case of particle contamination in various production facilities described above, there are many cases where adhesion of particles (or fine particles) having a particle size of several μm or more is a problem. In order to implement the above in the process area, an extremely large apparatus is required, and thus it is not practical to apply such a large-scale measuring apparatus.

  A technique obtained by improving the structure of the above-described DMA is disclosed in Patent Document 1. The fine particle classifying device disclosed in Patent Document 1 has a plurality of center electrode portions for each particle size as a characteristic configuration, and a particle outlet slit is individually formed in each of the center electrode portions for each particle size. This makes it possible to simultaneously classify (particle size selection) fine particles having a plurality of types of particle sizes.

  However, even with this improved fine particle classifier, the above problem still remains, that is, a clean room where adhesion of charged particles (or fine particles) having a particle size of several μm or more is a problem without increasing the scale of the device. In the actual environment such as the above, the problem of precisely measuring or specifying the charged amount of the charged particles cannot be solved.

  Therefore, as shown in FIG. 5, the present inventors take in air A containing charged particles p,... Floating in a room such as a clean room, and sense the particle size of the introduced charged particles p. An introduction part P provided with the illustrated particle sensor, a flow rate adjustment part R for adjusting the flow rate of air A passing through the introduction part P, an imaging cell V equipped with an electric field generation mechanism shown in FIG. 6, and a laser beam LZ1 An imaging unit Qa including a laser oscillator Z to be irradiated, a light transmission system unit W, and a light reception system unit Y, and a control unit S that receives data on charged particles transmitted from the particle sensor and controls the operation of the flow velocity adjustment unit R. Thus, the development of the charge amount specifying device T, which is roughly configured, has been completed.

  The above-mentioned DMA of the conventional structure specifies the charge amount by measuring the particles that have moved into the slit using the air flow, gravity, and Coulomb force of charged particles (this particle can also be called aerosol) as parameters. On the other hand, the charge amount specifying device T is a gas containing the charged particles p. For example, by setting the flow of the air A to a stationary state, the charged particles p move using only gravity and Coulomb force as parameters. The speed is measured by the imaging unit Qa of the optical system, and the charge amount or the number of charges is specified.

  The introduction part P, the flow velocity adjustment part R, and the imaging part Qa are connected in series via a pipe L through which the air A flows, and the air A including the charged particles p,. When flowing through the pipe L and passing through the flow rate adjusting unit R, the flow rate is reduced, and when introduced into the imaging unit Qa through the pipe L, the flow rate is zero or approximated by it. The flow rate control by the flow rate adjustment unit R is executed so as to achieve the above speed.

  In addition to the actuator valve R1, the flow rate adjusting unit R provides a fluid supply mechanism R2 including a compressor that provides high-pressure fluid or the like to the air A to reduce the speed of the air A, and a controller that performs opening / closing control of the valve. The actuator valve R1 is closed before the air A is taken into the introduction part P. When the air A is taken in, the actuator valve R1 is controlled to be opened by a control unit S built in a computer (not shown), and the air valve A1 starts to be taken into the introduction unit P when the actuator valve R1 is opened. In the introduction unit P, the particle size and the number of particles of the charged particles p mixed in the air A, and the flow velocity of the air A are sensed by the built-in particle sensor, and the charged particle data and flow velocity data are detected. It is transmitted to the control unit S. In the control unit S, the flow rate of the air A is reduced by the flow rate adjustment unit R, and at least when the air A is introduced into the imaging unit Qa on the downstream side, the speed becomes zero or a speed approximate thereto. In addition, adjustment of the opening degree of the actuator valve R1 of the flow velocity adjusting unit R, adjustment of the flow rate and fluid pressure of the pressure fluid from the fluid providing mechanism R2, and the like are performed.

  As shown in FIG. 6, the imaging unit Qa introduces the charged particles p and has a detection cell V provided with an electric field generation mechanism such as an internal electrode therein, a laser oscillator Z for irradiating the laser beam LZ1, and a light transmission system unit. W and a light receiving system unit Y are roughly configured.

  The light transmission system unit W includes a condensing lens Wa that condenses the irradiated laser light LZ1, and a focusing lens Wb that focuses the laser light LZ1 that has passed through the condensing lens Wa on the charged particles p. They are integrated with a frame Wc. On the other hand, the light receiving system unit Y is composed of a condensing lens Ya that condenses the scattered light LZ2 emitted by the charged particles p, and a focusing lens Yb that focuses the scattered light LZ2 that has passed through the condensing lens Ya. They are integrated with a frame Yc.

  In the focusing lens Yb of the light receiving unit Y, the focusing is executed and focused so that the image focus of the charged particles p is focused by the imaging unit U such as a CCD camera disposed in front of the focusing lens Yb. An image related to the charged particles p is transmitted to a computer having the control unit S or a separate computer, and an administrator confirms the image on the computer screen and calculates the charge amount of the charged particles p using the image. It can be executed.

  According to the charge amount specifying device T shown in the figure, when measuring the moving speed of the charged particles, first, since the flow of the air A containing the charged particles p is stationary, the Coulomb force is not further considered (ignored). In this case, the moving speed of the charged particles p is only the terminal sedimentation speed due to gravity, and the moving speed of the charged particles p is relatively higher than that when the moving speed is determined from gravity, air flow, and Coulomb force. Slow. For this reason, the moving path of the charged particles required for measurement may be short, and the apparatus itself can be downsized.

  Furthermore, the above-mentioned DMA with a conventional structure is a device that guides charged particles to the slit by applying a voltage to the electrode (inner cylinder) and applying a Coulomb force to the charged particles, so the amount of charge is unknown Under these conditions, it is necessary to change the voltage as a parameter in various ways to match the charge amount (charge number) of the particles. Therefore, in an environment where there are few floating particles such as in a clean room, in addition to the measurement of charged particles, the voltage is tentatively determined, and as a result, the measurement flow assumes that the number of charges is specified by the number of charges when classification is possible. If classification cannot be performed, it is necessary to change the voltage to temporarily determine the same and repeat the same operation until classification can be performed again. It is easy to understand that it takes a lot of time to specify the charge amount. On the other hand, the charge amount specifying device T can measure and specify the charge amount while confirming the movement state of the measured charged particles, greatly reducing the time required for specifying the charge amount of the charged particles. It can be done.

  By the way, the size of the illustrated detection cell V serving as an imaging unit is about 14 × 7 × 6 mm, and the capacity thereof is about 0.6 ml. Therefore, when air in a clean room of Class 1000 (35 μl of 0.5 μm particles / l) is sucked by the introduction part P using the charge amount specifying device T shown in the figure, 0.021 particles are in the imaging cell V. Will exist. This is equivalent to capturing two particles in 100 measurements. Further, in this apparatus, it takes about 15 seconds for a series of operations of air suction, valve closing (about 10 seconds), and photographing (about 5 seconds). Therefore, one image can be taken every 750 seconds.

  Here, it is important to evaluate the charge number of the charged particles as a charge number distribution. In this charge number distribution evaluation, it is necessary to photograph about 50 charged particles and measure the charge number. Therefore, a shooting time of 750 seconds / piece × 50 pieces = 37500 seconds = 10 hours and 25 minutes is required. That is, by applying the illustrated charge amount specifying device T, the time required for specifying the charge amount can be shortened as compared with the conventional charge amount specifying device, but further reduction in time is desired in the technical field.

  Furthermore, according to the present inventors, as a result of actually conducting an experiment in a clean room of Class 1000, there was a fact that charged particles could not be captured during 200 measurements, and there are two main reasons for this. .

  The first factor is that air in the imaging cell V is not related to particle trapping and is repeatedly closed and imaged at intervals of at least 10 seconds, so that it is not always necessary when the valve (actuator valve R1) is closed. It is not always possible to capture charged particles.

  The second factor is that the captured charged particles can be photographed only when passing through a portion where laser scattered light having a constant intensity can be obtained even in the photographing cell V.

  As described above, the charge amount specifying device T can reduce the size of the device itself, and has the effect that the time required for specifying the charge amount of the charged particles can be greatly reduced as compared with the conventional device. For example, when the concentration of charged particles in the atmosphere is low, the charged particles often pass through the imaging cell, resulting in low charged particle trapping efficiency. It has a problem of becoming. Further, in evaluating the charge number of charged particles as a charge number distribution, there is a problem of further shortening the time required for photographing about 50 charged particles.

JP 2007-315817 A

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a charged particle amount specifying device for charged particles that can further reduce the time required for photographing charged particles and has high charged particle capturing efficiency. To do.

  In order to achieve the above object, the charged particle amount identification device according to the present invention includes a suction unit, a detection unit that senses charged particles while taking in gas containing charged particles floating by operating the suction unit, An imaging unit that is connected to the detection unit by a pipe line and that captures charged particles by introducing the gas that has passed through the detection unit, an open / close valve provided in the pipeline, and sensing of charged particles from the detection unit A control unit that controls the opening / closing valve to be closed when data is transmitted, and the sensing unit senses charged particles, and the sensing data is transmitted to the control unit to control the opening / closing valve to be taken in. The charged particles are captured downstream of the open / close valve in the pipeline, and the imaging unit has an irradiation mechanism for irradiating laser light, and the charged particles are irradiated with laser light. It is to determine the charge amount of the charged particles from the received light data of the emitted light scattered from charged particles upon.

  The charge amount specifying device of the present invention actually shoots charged particles and measures the charge amount in order to precisely detect that charged particles (this particle can also be called aerosol) are taken into the device. First, a detection unit is provided on the upstream side where the gas containing the charged particles flows than the imaging unit to be identified, and the detection unit and the imaging unit are connected by a pipe and an opening / closing valve is provided in the middle of the pipe.

  The gas is taken into the apparatus by operating a suction unit such as a pump. The gas taken into the apparatus by operating the suction unit first passes through the detection unit.

  When charged particles are sensed by the detection unit, the sensing data is transmitted to the control unit, and the open / close valve is controlled to be closed. By closing the open / close valve in the middle of the pipeline, it is possible to prevent the charged particles that have been taken into the apparatus and more specifically moved downstream from the open / close valve from being released to the outside of the apparatus, The charged particles sensed by the detection unit can be reliably introduced to the imaging unit downstream of the opening / closing valve. The operation of the suction unit can also be executed by this control unit, and when the device is ON-controlled, the suction unit is operated based on the operation command signal from the control unit to perform gas suction, and simultaneously detected The mode which can perform detection of the charged particle in the gas introduced by the operation command signal being transmitted to the unit may also be used.

  In the photographing unit, the introduced charged particles are irradiated with laser light, and the charge amount of the charged particles is specified based on the received light data of the scattered light reflected by the charged particles by this laser light irradiation. This charge amount is specified by acquiring received light data with a CCD camera or the like constituting the photographing unit, and reading the received light data with an image reading device or the like to specify the particle size and moving speed of the charged particles. The charge amount is specified (measured) based on the above.

  According to the above-described charge amount specifying device of the present invention, for example, even when the concentration of charged particles in the atmosphere is low, charged particles are sensed by the detection unit, and the on-off valve is closed and captured in the device. Since charged particles are surely introduced into the photographing unit, there is no problem that the charged particles pass through the photographing unit and photographing is not performed, and a device with extremely high charged particle capturing efficiency (or charged particle photographing efficiency) Become. Therefore, in evaluating the charged number of charged particles as a charge number distribution, the time required for photographing about 50 charged particles can be significantly reduced as compared with the above-described conventional apparatus.

  Here, the detection unit includes a detection cell through which the gas passes, an irradiation mechanism that irradiates the gas with laser light, and a light receiving mechanism that receives scattered light emitted from charged particles, and the control unit In the embodiment, a voltage intensity threshold value related to scattered light is stored, and the open / close valve is controlled to be closed when sensing data transmitted from the light receiving mechanism is equal to or greater than the voltage intensity threshold value.

  The apparatus of the present embodiment irradiates a laser beam in the detection unit as well as the imaging unit, receives the scattered light, transmits the received light data to the control unit, and further detects charged particles in the detection unit. In order to suppress erroneous detection, a voltage intensity threshold value related to scattered light emitted from charged particles is set in advance, and the data is stored in the control unit. The scattered light reception data transmitted from the detection unit is the voltage intensity. In order to prevent the charged particles from being trapped when the charged particles are trapped when the threshold value is exceeded, the closing control of the opening / closing valve is executed.

  The irradiation mechanism includes a laser oscillator, a condensing lens that condenses the laser light emitted from the laser oscillator, and a focusing lens that focuses the laser light that has passed through the condensing lens on the charged particles. The mechanism is applicable to a configuration including a condensing lens that condenses scattered light emitted by charged particles and a focusing lens that focuses the scattered light that has passed through the condensing lens.

  According to the apparatus of the present embodiment, erroneous detection of charged particles in the detection unit is suppressed, and charged particles are captured with higher detection accuracy and photographed to determine the particle size and charge amount of charged particles. Can be done.

  Further, the control unit stores predetermined time data until the gas passes from the detection unit to the imaging unit via the pipe line, receives the sensing data, and after the predetermined time has elapsed, An embodiment in which the on-off valve is controlled to be closed is desirable.

  When closing the open / close valve, the charged particles detected by the detector pass through the pipeline, pass through the open / close valve on the way, and are further controlled when the open / close valve is introduced downstream. Thus, for example, when the charged particles are moving to the upstream side of the opening / closing valve, the opening / closing valve is closed and the introduction to the photographing unit can be prevented from being blocked.

  Therefore, in the apparatus of the present embodiment, predetermined time data until the gas passes from the detection unit to the imaging unit via the conduit is stored in advance in the control unit, and the control unit receives the sensing data. The opening / closing valve is controlled to close after a predetermined time has elapsed.

  This “predetermined time” varies depending on the flow velocity of charged particles or gas, the pipe diameter and length of the pipe, and the like. The predetermined time may be calculated from the diameter and length of the pipes to be configured and stored in the control unit, or the detection unit detects the speed of the charged particles and maintains this speed. Alternatively, the control unit may determine the “predetermined time” to the photographing unit in consideration of a certain deceleration.

  As can be understood from the above description, according to the charged particle amount specifying device of the present invention, the charged particle is detected on the upstream side where the gas containing the charged particles flows rather than the image pickup unit that picks up the charged particle and specifies the charged amount. The detector is connected to the imaging unit with a conduit, and an open / close valve is provided in the middle of the conduit, and the charged charge is detected while precisely detecting that charged particles have been taken into the device. By capturing and photographing particles reliably, it becomes an apparatus with extremely high charged particle capturing efficiency or charged particle capturing efficiency.

It is explanatory drawing explaining the apparatus structure of the charge amount specific apparatus of this invention. It is a block diagram explaining a control part. It is the figure which showed an example of the time series graph of the voltage intensity regarding the scattered light in the detection part after operating an apparatus. It is the figure which showed an example of the charge number distribution of the charged particle for every particle diameter. It is explanatory drawing explaining the apparatus structure of the conventional charge amount specific apparatus. It is sectional drawing of the imaging | photography part which comprises the charge amount specific apparatus shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the charge amount specifying device of the present invention may be applied to the device configuration part or all of the configuration of the conventional device shown in FIGS. it can.

FIG. 1 is an explanatory diagram for explaining the device configuration of the charge amount identification device of the present invention.
The illustrated charge amount specifying device 100 includes a suction unit 40 (suction pump) serving as a suction source for taking in air A including charged particles p,... Floating in a room such as a clean room, and charged particles together with the sucked air A. a detector 10 that detects whether or not p has been taken into the apparatus; a pipe L that passes the detector 10 and flows air A downstream to the apparatus; An opening / closing valve 30 capable of closing the suction force of the portion 40 and blocking the flow of the air A in the pipe L, and a photographing portion 50 which is located downstream and into which the charged particles p taken together with the air A are introduced. The control unit 20 is configured to perform a closing control on the opening / closing valve 30 based on sensing data indicating that the detection unit 10 has detected charged particles.

  The detection unit 10 includes a detection cell 11 into which air A containing charged particles p is introduced, a laser oscillator 12 and a light transmission system unit 13 that irradiate laser light that constitutes an irradiation mechanism, and a light receiving system unit 14 (light receiving mechanism). And is composed of. The light transmission system unit 13 includes a condensing lens (not shown) that condenses the irradiated laser light, and a focusing lens (not shown) that focuses the laser light that has passed through the condensing lens on the charged particles p. They are configured and integrated with a frame (not shown). On the other hand, the light receiving system unit 14 includes a condensing lens (not shown) that condenses the scattered light emitted from the charged particles p, and a focusing lens (not shown) that focuses the scattered light that has passed through the condensing lens. They are integrated with a frame (not shown).

  The charged particles p taken in by the detection unit 10 are introduced into the photographing unit 50 via a pipe line L having a pipe diameter φ and a pipe length t (the opening / closing valve 30 is located in the middle thereof).

  The imaging unit 50 includes an imaging cell 51 into which charged particles p are introduced, a laser oscillator 52 that irradiates laser light, a light transmission system unit 53, and a CCD camera 54. The light transmission system unit 53 includes a condenser lens (not shown) that collects the irradiated laser light, and a focusing lens (not shown) that focuses the laser light that has passed through the condenser lens on the charged particles p. They are configured and integrated with a frame (not shown).

  In the imaging unit 50, scattered light emitted by charged particles moving in the imaging cell 51 is acquired as received light data by the CCD camera 54, and the received light data is read by an image reading device (personal computer 60) to determine the particle size of the charged particles. The moving speed is specified, and the charge amount is specified based on these specifying results.

Here, an outline of an algorithm for specifying the charge amount from the particle diameter and the moving speed will be described.
When charged particles are introduced into an electric field having an electric field strength E (V / m), the charge amount n _p e (C) of the particles is expressed by the following formula 1.

ここで、D_pは粒径(m)、v_etは粒子の移動速度(m/s)、C_cはカニンガムの補正係数、e＝1.60217733×10^-19(C)であり、その導出式を以下の式２で示す。また、μはエアの粘度で、0.018110^-3(Pa・s)である。

Where D _p is the particle size (m), v _et is the particle moving speed (m / s), C _c is the Cunningham correction factor, e = 1.602 17733 × 10 ^-19 (C), and the derivation formula is It is shown by the following formula 2. Further, μ is the viscosity of air and is 0.018110 ⁻³ (Pa · s).

ここで、K_nはクヌーセン数で、エアの平均自由行程をλとすると、以下の式３で表すことができる。

Here, K _n in the Knudsen number, when the mean free path of the air and lambda, may be represented by the formula 3 below.

  From the above formulas 1 to 3, it can be seen that the charge amount of the charged particles depends on the particle size and the moving speed of the particles in the electric field, and the charge amount of the charged particles can be specified from these measurement data.

  The charge amount identification device 100 shown in the figure is more charged particles than the photographing unit 50 that actually photographs the charged particles p and identifies the charge amount so as to precisely detect that the charged particles p have been taken into the device. First, the detection unit 10 is provided on the upstream side where the air A containing p flows, and when sensing data indicating that the charged particles p are detected is transmitted from the detection unit 10 to the control unit 20, a pipe line is connected from the control unit 20. A command signal for controlling the closing of the opening / closing valve 30 in the middle position of L is transmitted.

Here, the internal structure of the control unit 20 will be outlined with reference to the block diagram of FIG.
The illustrated control unit 20 includes a sensing data input unit that transmits sensing data (scattered light reception data) indicating that the charged particles p are detected from the detection unit 10, and a voltage intensity threshold storage unit that stores a voltage intensity threshold. It has. This is a means for suppressing erroneous detection of the charged particles p in the detection unit 10, and a voltage intensity threshold value related to scattered light emitted from the charged particles p is input in advance to the voltage intensity threshold value storage unit. The scattered light reception data transmitted from 10 and the stored voltage intensity threshold are compared by the comparison calculation unit, and when the scattered light reception data is equal to or greater than the voltage intensity threshold, the charged particle p is charged as captured by the detection unit 10. In order to prevent the particles p from flowing out of the apparatus, a closing control command signal is transmitted to the opening / closing valve 30 via the closing control command unit.

  FIG. 3 shows an example of a time-series graph of voltage intensity related to scattered light in the detection unit 10 after the device 100 is operated. Since the possibility of noise is high when the voltage is low, it is preferable to set a voltage of a certain level (0.05 V in FIG. 3) as the voltage intensity threshold.

  In the closing control of the opening / closing valve 30, the charged particles p detected by the detection unit 10 pass through the pipe line L, pass through the opening / closing valve 30 on the way, and further, the shooting cell 51 of the shooting unit 50 located downstream thereof. It is preferable that the opening / closing valve 30 is controlled to be closed when it is introduced into the camera. With such control, for example, when the charged particles p are moving upstream of the opening / closing valve 30, the opening / closing valve 30 is closed, 50 can be prevented from being introduced.

  For this purpose, the control unit 20 stores time data until the gas A passes from the detection unit 10 through the pipe L to the imaging unit 50 in a predetermined time storage unit, and the control unit 10 receives the sensing data. Thus, the opening / closing valve 30 is controlled to close after a predetermined time has elapsed.

  When the predetermined time is input to the predetermined time storage unit, the predetermined time varies depending on the flow velocity of the charged particles p or gas A, the pipe diameter φ of the pipe L, the pipe length t, and the like. The predetermined time may be calculated from the rule of thumb of the velocity of the gas taken into the apparatus 100 and the pipe diameter φ or the pipe length t of the pipe L constituting the apparatus, and this may be inputted. Then, the speed of the charged particles p is detected, and the control unit 20 calculates a predetermined time to the photographing unit 50 while maintaining this speed or taking into account a certain deceleration, and a close control command signal after the determined predetermined time. May be transmitted.

  According to the illustrated charge amount identification device 100, the detection unit 10 is provided on the upstream side where the gas A containing the charged particles p flows from the imaging unit 50 that captures the charged particles p and identifies the charge amount. 10 and the photographing unit 50 are connected by a pipe L, and an opening / closing valve 30 is provided in the middle of the pipe L so that the charged particles p taken in while accurately detecting that the charged particles p have been taken into the apparatus 100. The particles p can be reliably captured and photographed, so that the apparatus has extremely high charged particle capturing efficiency or charged particle capturing efficiency.

  Further, according to the charge amount identification device 100, the gas A is continuously sucked until the detection unit 10 senses the scattered light of the particles. Therefore, when suctioned in a clean room of Class 1000 (35 μl particles of 0.5 μm), one particle passes through the detection unit 10 in 60/35 seconds≈1.7 seconds, and the valve is automatically closed. Since approximately 15 seconds are required for a series of operations (approximately 10 seconds) and photographing (approximately 5 seconds), one image can be captured every 16.7 seconds.

  It is important to evaluate the charge number of the charged particles as a charge number distribution as shown in FIG. 4. As described above, in this charge number distribution evaluation, about 50 charged particles are photographed and the charge number is photographed. However, the time required for the conventional apparatus described above can be shortened to 1/44 of 750 seconds / piece, and 50 charged particles can be imaged and the number of charges. The time required for the measurement can be significantly reduced from 10 hours 25 minutes to 14 minutes.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 10 ... Detection part, 11 ... Detection cell, 12 ... Laser oscillator, 13 ... Light transmission system unit, 14 ... Light reception system unit, 20 ... Control part, 30 ... Opening / closing valve, 40 ... Suction part (suction pump), 50 ... Photographing , 51 ... photographing cell, 52 ... laser oscillator, 53 ... light transmission system unit, 54 ... CCD camera, 60 ... personal computer, 100 ... charge amount specifying device, L ... conduit, A ... air (gas), p ... Charged particles

Claims (2)

A suction part;
Incorporating a gas containing charged particles floating by operating the suction unit, a sensing unit for sensing the scattered light of the charged particles,
An imaging unit that is connected to the detection unit by a pipe line and that images the charged particles by introducing the gas that has passed through the detection unit;
An on-off valve provided in the pipeline;
A control unit that controls the closing of the open / close valve when sensing data of scattered light of charged particles is transmitted from the detection unit,
The detection unit senses the scattered light of the charged particles , and the sensing data is transmitted to the control unit to control the closing of the opening / closing valve, and the charged particles that have been taken in are located downstream of the opening / closing valve in the pipeline. To capture,
The detection unit includes a detection cell through which the gas passes, an irradiation mechanism that irradiates the gas with laser light, and a light receiving mechanism that receives scattered light emitted from charged particles,
A voltage intensity threshold value related to scattered light is stored in the control unit, and when the sensing data transmitted from the light receiving mechanism is equal to or higher than the voltage intensity threshold value, the open / close valve is controlled to be closed,
The photographing unit includes a photographing cell and an irradiation mechanism for irradiating laser light,
When the charged cell is irradiated with laser light by generating an electric field in the imaging cell, the particle size and moving speed of the charged particle are determined from the received light data of the scattered light emitted from the charged particle, and the charged amount of the charged particle is specified. , Charge amount identification device for charged particles. In the control unit, the gas has been predetermined time data stored up leading to the imaging unit through the conduit from the sensing unit to receive the sensing data, the on-off after the elapse the predetermined time The charged particle amount specifying device for charged particles according to claim 1 , wherein the valve is controlled to be closed.

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