JPS63208737A - Method for measuring amount of generated dust - Google Patents

Abstract

PURPOSE:To measure the amt. of dust in gas by providing a material to be measured in a vessel to isolate the same from the outdoor air, passing a clean gas in the vessel and sampling a part of the gas. CONSTITUTION:The material 2 to be measured subjected to a pretreatment such wiping with a low dust-generatable non-woven fabric is disposed in a measuring chamber 1 and a blower 5 is operated to introduce the cleaned air or the like into the chamber 1. The number of the dust in the cleaned air sampled by a sampling tube 10 is measured by a light scattering type particle counter 8 after a normal state is attained in the chamber. The dust sticking to the material 2 is removed in this state by which the cleanliness of the background is obtd. The material 2 is then operated and the number of the generated dust is measured when a moving mechanism is operated under prescribed conditions, by which the cleanliness at the time of the movement is obtd. The amt. of the generated dust from the moving mechanism is determined by subtracting the cleanliness of the background from the cleanliness at the time of the movement.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) The present invention relates to a method for measuring the amount of dust generated, and in particular to an apparatus used in a place requiring a clean environment, and a method for measuring the movement of the apparatus. The present invention relates to a method for measuring the amount of dust generated that is suitable for use in measuring the amount of dust generated from.

(Prior art) For example, in the manufacturing of semiconductor devices, there are many processes that require an extremely clean atmosphere, such as the process of forming fine patterns on semiconductor wafers, and such processes are generally carried out in a clean room. It will be held in

In general, a clean room has a down flow in which clean air that has been purified using an ultra-high performance air filter is distributed from the top to the bottom, and dust generated from equipment, human bodies, etc. inside the clean room is It is configured to be discharged from the floor.

However, the development of semiconductor device manufacturing technology is remarkable, and ultra-V and thinning are progressing. With this ultra-fine design, dust is directly affected, so clean rooms are also class 1.
An environment that maintains ultra-cleanliness of 0, class 1 etc. is required,
Since only a few people will be allowed to enter the room, the equipment used to enter the room will be automated. Therefore, it is necessary to extremely limit the amount of dust generated by automated equipment.In order to develop automated equipment that generates zero or less dust, a highly accurate quantitative method for measuring the amount of dust generated is required.

Conventionally, when measuring such emitted mx, the device to be measured is placed in a clean room, the gas sampling part of the light scattering particle counter is placed near the moving part of the device, and the device is placed near the device to be measured in the operating state. Methods such as collecting dust and measuring the amount of dust generated were used.

(Problems to be Solved by the Invention) However, the above-mentioned conventional method has the problem of requiring a large-scale facility such as a clean room, and the influence of downflow in the clean room, other equipment in the clean room, human body, etc. There is a problem in that the amount of dust generated cannot be accurately measured because of the intrusion of dust generated from the device and the scattering of dust generated from the device to be measured.

The present invention has been made in response to such conventional circumstances, and is capable of accurately and quantitatively measuring the amount of dust generated in the operating state of an object to be measured without requiring a large-scale facility such as a clean room. The purpose of this study is to provide a method for measuring the amount of dust generated.

[Structure of the Invention] (Means for Solving the Problems) In other words, the method for measuring the amount of dust generated according to the present invention includes: placing an object to be measured in a container to isolate it from the outside air, passing clean gas into the container, The method is characterized in that at least a portion of the gas that has passed through the container is sampled, and dust stars in the sampled gas are measured.

(Function) In the method for measuring the amount of dust generation of the present invention, the object to be measured to be tested is placed in a container to isolate it from other dust-generating bodies, and a cleaning agent is circulated from the top to the bottom in the measurement chamber. Form a gas flow.

Then, for example, dust generated from the object to be measured in an operating state is collected from inside the exhaust pipe together with a part of the circulating gas, and the number of dust particles is measured.

Therefore, it is not affected by dust generated from other dust generators, and by efficiently collecting dust from exhaust pipes, etc., it is possible to accurately generate dust without the need for large-scale facilities such as clean rooms. can be measured.

(Example) An example of the method for measuring the amount of dust generated according to the present invention will be described below with reference to the drawings.

The measurement chamber 1 is made of a material such as a transparent hard vinyl chloride plate (antistatic plate) that has been subjected to antistatic treatment, and has an inner diameter of, for example, 300 in to 500 nn, and a height of, for example, 200 in.
It is formed into a cylindrical shape with a size of about nn to 400111, and the inside is configured to be visually visible.

Further, in this measurement chamber 1, a holding device tN1a for holding the object to be measured 2 is arranged. This retention fiml
It is desirable that a has a shape that does not disturb the gas flow within the measurement chamber 1;
It is composed of two mirror-finished stainless steel round rods each having a diameter of, for example, about 8 fl 1 m and arranged at an interval of about 80 nn. The earth 1a of this stainless steel round bar is grounded.

Furthermore, the measuring chamber 1 is configured such that the cleaning gas passes through the measuring chamber 1. That is, an introduction pipe 4 made of a flexible duct or the like is connected to the upper part of the measurement chamber 1 via a filter storage chamber 3.
It is connected to an air blowing means such as

Note that, for example, the cross section of the filter storage chamber 3 is partially 200 mm.
It has a shape such as a square of about n11 to 4G0n11, and a pre-filter 3a is arranged at the upper part, and an ultra-high performance air filter 3b such as a Ulva filter is arranged at the lower part. It is preferable that the filter housing chamber 3, pre-filter 3a, and ultra-high-performance air filter 3b have a size and shape that allow cleaning gas to be sprayed over the entire object 2 to be measured. Further, the type of filter may be any type as long as it can remove the dust to be measured to an almost zero level when the object 2 to be measured does not move, and provide clean gas.

A measurement system capable of accurately and quantitatively measuring dust generated on the object 2 to be measured is disposed at the lower part of the measurement chamber 1 . That is, the exhaust pipe 8 is connected via the bell mouth reducer 7. A sampling pipe 10 connected to a light scattering particle counter 9 is disposed within the exhaust pipe 8.
On the downstream side of the pipe where the sunblink pipe 10 is arranged, a flow rate measuring means consisting of, for example, an orifice lla and a pressure gauge (digital manometer) 11b is arranged.

As shown in FIG. 2, the bell mouth reducer 7 is made of, for example, a stainless steel plate with a mirror finish, and the bell mouth reducer 7 is connected to an earth 7a. , the inner diameter is about 100n++i to 400nn, and the diameter C of the opening end is about 1.6 times that of the inner diameter, and the symbols d, e, and f in the figure
, the R of the area indicated by g is 0.0 for the inner diameter, respectively.
It has a shape that combines multiple types of R with a radius of 2.0.33.0 and 2.0.305 times, for example, from the measurement chamber 1 whose inner diameter is about 1.6 times the inner diameter. The gas flow is constricted into the exhaust pipe 8 without causing turbulence or the like. That is, when turbulence or the like occurs here, dust stagnation, deviation, etc. occur, new dust generation, etc. occur, and it becomes difficult to accurately measure the amount of dust generated from the object to be measured.

The sampling tube 10 is made of antistatically treated urethane or the like, and its tip is formed into a cylindrical shape made of mirror-finished stainless steel or the like, as shown in FIG. A cylindrical member 10a is arranged.

The cylindrical member 10a has a total length of, for example, about 50 mm, and the outer diameter l and wall thickness j of the tip are 6.8 nm and 0°15 m, respectively.
The outer diameter k and wall thickness of the side ends are each 8. Oni, 0.
The diameter is 2 mm, and the tip is formed into a tapered shape with a small diameter and thin wall. That is, the structure is such that turbulence does not occur in the sampling tube 10 and its tip when collecting dust. This cylindrical member 10a is for collecting a part of the gas from the measurement chamber 1 without disturbing the gas flow. Furthermore, the sampling tube 10 also has approximately 800
In, the inside of the exhaust pipe 8 is gradually extended diagonally downward,
The exhaust pipe 8 is led out from the wall and is configured to prevent turbulence from occurring in the gas sampling section.

Further, the position of the cylindrical member 10a can be adjusted up and down and left and right 41 so that it can be selected as appropriate! lying down Then, a part of the gas is guided out of the exhaust pipe 8 by the cylindrical member 10a and the sampling pipe 10, and the amount of dust is counted by the light scattering particle counter 9. This light scattering type particle counter 9 is provided with an inlet I1 for effectively introducing dust.

The cylindrical member 10a at the tip of the sampling tube 10 has a tip with a constant radius, as shown in FIGS. 4 and 5.
It may also be a shape that expands with the opening, or a shape that gradually expands toward the opening end.

Next, a method of this embodiment using the apparatus having the above configuration will be explained. The object to be measured 2, which has been pretreated by wiping it with a low-dust-producing nonwoven cloth or blowing cleaning air, is placed in the measurement chamber 1, and first the operation of the object to be measured 2 is stopped. Then, the blower 6 is operated to introduce clean air or the like into the measurement chamber 1, and a preparatory operation is performed for a predetermined period. After reaching a steady state, the number of dust particles in the clean air sampled by the sampling tube 10 is measured by the light scattering particle counter 9. Note that suction is performed from the sampling tube 10, but the sampling tube 10 is closed so that the direction of the flow of sampled air does not change at the tip of the sampling tube 10.
The amount of air blown by the blower 6 and the inner diameter of the cylindrical member 10a at the tip of the sampling tube 10 are adjusted so that the tip of the sampling tube 10 is arranged and the flow rate of the sampled air is approximately equal to the flow rate of the air flowing in the surrounding exhaust pipe. It is preferable to adjust the amount of suction and the amount of suction. In this state, first remove the dust attached to the object to be measured 2, check that the number of dust measured by the light scattering particle counter 9 is almost zero, and set the background cleanliness to 0, then , the object to be measured 2 is operated, and the number of dust generated when the motion R structure is moved under predetermined conditions is measured and taken as the cleanliness level during the movement. In this measurement, the position of the cylindrical member 10a at the tip of the sampling tube 10 is
It is preferable to move it in the plane direction and measure at multiple locations. The amount of dust generated from the movement mechanism is determined by subtracting the background cleanliness from the cleanliness during this movement, and if the flow rate of the gas flowing into the measurement chamber 1 is measured and converted into units, the amount of dust generated by the object to be measured 2 The total amount of dust can be calculated from

The operation of the object to be measured 2 is 'gA!' when measuring the amount of a emitted from a moving mechanism such as a motor. The lJ section, heater, etc. are accommodated in the measurement chamber 1, and a through hole 1b provided in the side wall of the measurement chamber 1
The gap between the power cable, control cable, etc. and the through hole 1b is sealed with silicone or the like to prevent outside air from entering.

In addition, when measuring the amount of dust generated only from the target movement a structure, excluding the driving part such as the motor, place the driving part such as the motor 2a outside the measurement chamber 1 as shown in FIG. Through hole 1b
The motor 2a and the movable part of the object to be measured 2 are connected by a shaft 2C that is loosely inserted into the shaft 2C. In such a case, the gap created between the periphery of the shaft 2C and the through hole 1b is sealed with a magnetic fluid or the like.

That is, in this embodiment method, the object to be measured 2 is placed in the measurement chamber 1.
Since it is housed inside and isolated from other dust generating bodies, it is not affected by dust generated from other dust generating bodies, and
The sampling pipe 10 is arranged in an exhaust pipe 8 connected to the lower part of the measurement chamber 1 via a bell mouth reducer 7, and can efficiently collect dust without disturbing the gas flow. Even in a low atmosphere,
The amount of dust generated from a desired measurement site can be accurately measured.

Further, there is a possibility that dust generated from the object to be measured 2 is electrostatically charged and adheres to the object to be measured 2, thereby disturbing the airflow.

This phenomenon is remarkable when the object to be measured 2 is made of an insulator. As a countermeasure against such static electricity, it can be improved by arranging a static eliminator 20 on the outflow side of the filter 3 as shown in FIG. 6, making it possible to perform measurements with higher accuracy.

This static eliminator may be a well-known one, for example, as shown in Fig. 7(A).
As shown in FIG. 2, a plurality of sets of discharge columns 72 are formed using an annular ring 71 made of an insulator corresponding to the inner diameter of the measurement chamber 1 as a frame. This discharge column 72 is provided with a rod-shaped static elimination electrode 74 having a row of discharge needles 73 formed in the middle thereof, and ground electrodes 75 and 76 are provided to sandwich this static elimination electrode 74, thereby forming the discharge column 72. The configuration of this discharge column 72 is, for example, a static elimination electrode 74, a ground electrode 7
5.76 is located at the apex of the triangle.

As the ground electrodes 75 and 76, mirror-polished stainless steel rods with a diameter of, for example, about 81111 mm are used.
As shown in FIG. 7(B), a large number of discharge needles 73 are implanted in a line in a state of electrical connection on a stainless steel rod 77 having a diameter of, for example, about 51 Il, and the tips of the discharge needles 73 are exposed, and the stainless steel rod 77 is An insulating resin coating 78 is provided to cover the discharge needle 73, and the discharge needle 73 is wired in parallel with an external high voltage generating power source and a high voltage line. This coating 78 may be made of silicone resin, foamed resin, etc.
The cylindrical resin is cut in the longitudinal direction, and the discharge needles are arranged in a clasp with the 73 rows of discharge needles.

A static elimination bag T with a unique structure! By installing 20, it is possible to generate electricity using clean gas that eliminates static electricity! The amount of I can be measured. This can be achieved by generating a discharge between the metal discharge needle 73 of each discharge column 72 and the stainless steel rod 75,76.

Furthermore, in order to perform more accurate measurements, it is even more effective if a static eliminator 22 is provided in the inlet pipe 21 of the light scattering particle counter 9.

As shown in FIG. 8, the static eliminator 22 is arranged so as to surround the inlet pipe 21 connected to the sampling pipe 10.

That is, the bottom part 8 in each cylindrical conductive container 81 with the − side opening
A plurality of discharge vessels 85 are arranged at the apexes of a triangle, for example, with a plurality of discharge vessels 85 insulated from the vessel 81 and having metal discharge needles 83 arranged in a line at predetermined intervals.
Individually placed. Inlet side pipe 2 is placed inside the triangle configured in this way.
1, the static electricity charged on the inner wall of the inlet side pipe 21 can be neutralized and removed by the electrostatic effect by neutralizing and removing the static electricity charged on the outer wall of the inlet side pipe 21. This static electricity removal effect is achieved by the container 8 equipped with a ground scraper 84.
This can be achieved by generating corona discharge between the discharge needle 83 and the discharge needle 83 to generate ion pairs.

As shown in FIG. 6, the measurement results measured by the light scattering particle counter 9 are configured to be subjected to arbitrary data processing by a computer 30 and printed out in a desired data format by a printer 31. be able to.

Further, the motor 2a is connected to a control unit 40, CP
A U-board 41, a disk unit 42, a CRT 43, etc. can be connected to perform desired control.

〔Effect of the invention〕

As described above, the method for measuring molar emissions of the present invention does not require a large-scale facility such as a clean room, prevents the generated dust from adhering to the object to be measured, piping, etc., and prevents the spread of other dust. There is no interference or scattering of actual dust, and the amount of dust generated can be measured accurately and empirically.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a dust generation amount measuring device used in an embodiment method of the present invention, FIGS. 2 and 3 are partially enlarged sectional views showing the main parts of FIG. 1, and FIGS. 5 is a partially enlarged sectional view showing a modification of FIG. 3, FIG. 6 is an explanatory diagram of another embodiment of FIG. 1, and FIGS. 7 and 8 are explanations of the configuration of the static eliminator shown in FIG. 6. It is a diagram. 1...Measurement room, 1a...Earth, 2.
...Object to be measured, 3...Filter housing chamber,
4...Introduction piping, 6...Blower, 7.
... Bell mouth reducer, 7a ... Earth, 8 ... Exhaust piping, 9 ... Light scattering particle counter, 10 ... Sampling tube. Applicant Tokyo Electron Co., Ltd. Applicant Taisei Kensetsu Co., Ltd. Agent Patent Attorney Sa Suyama - Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 (A) - CB) Figure 7 Figure 8

Claims (7)

[Claims] (1) Place the object to be measured in a container to isolate it from the outside air, pass clean gas into the container, collect at least a portion of the gas that has passed through the container, and measure the amount of dust in the sampled gas. A method for measuring the amount of dust generated, characterized by measuring the amount of dust generated. (2) The sampling position of the gas that has passed through the container in which the object to be measured is provided is carried out multiple times at different positions within the piping of the gas flow path. How to measure the amount of dust generated. (3) The method for sampling the gas that has passed through the container in which the object to be measured is installed is characterized in that the sampled gas is suctioned so that the flow velocity of the sampled gas is approximately equal to the flow velocity of the circulating gas that has passed through the container. A method for measuring the amount of dust generated according to claim 1. (4) The method for measuring the amount of dust generated according to claim 1, wherein the gas flowed into the container in which the object to be measured is provided is gas that has passed through a static eliminator for removing static electricity. (5) A part of the gas that has passed through the container is sampled from a container in which the object to be measured is provided, and all piping through which the sampled gas passes is subjected to static electricity removal treatment. The method for measuring the amount of dust generated as described in paragraph 1. (6) Amount of dust generation as set forth in claim 1, characterized in that the flow path of the clean gas flow flowing inside the container in which the object to be measured is provided is configured so that turbulence is unlikely to occur. Measuring method. (7) The method of collecting the gas that has passed through the container in which the object to be measured is provided is carried out without changing the flow direction of the gas at the sampling inlet. How to measure the amount of dust generated.