JPH0785045B2 - Dust generation measurement method - Google Patents

Description

The present invention relates to a dust generation amount measuring method, and more particularly to a device used in a place requiring a clean environment and a motion mechanism of the device. The present invention relates to a dust generation amount measuring method suitable for measuring the dust generation amount from the air.

(Prior Art) For example, in the manufacture of semiconductor devices, there are many processes that require an extremely cleaned atmosphere, such as a process of forming a fine pattern on a semiconductor wafer. Such a process is generally performed in a clean room. Done in.

Generally, in a clean room, a downflow is formed in which clean air purified using an ultra-high performance air filter is distributed from the upper part to the lower part, and dust generated from devices in the clean room, human bodies, etc. It is configured to be discharged from the floor.

However, the development of semiconductor device manufacturing technology is remarkable, and ultra-miniaturization is progressing. Due to the direct impact of dust with this ultra-miniaturization, clean rooms are also class 1
An environment that maintains ultra cleanliness of 0, class 1, etc. is required,
Since there are only a few people entering the room, the equipment inside will be automated. Therefore, it is necessary to extremely limit the amount of dust generated by automated equipment. Highly accurate quantitative dust amount measurement methods are necessary for the development of automated equipment that generates little dust.

Conventionally, when measuring such a dust generation amount, the device to be measured, etc. is arranged in a clean room, and the gas sampling part of the light scattering type particle counter is arranged in the vicinity of the moving part of the device to measure the device under operation. Methods such as collecting dust in the vicinity and measuring the amount of dust generation have been performed.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional method, a problem that requires a large-scale facility such as a clean room, an influence of downflow in the clean room, an apparatus or a human body in the clean room, etc. There is a problem in that the amount of dust generated cannot be accurately measured due to dust that has come around and scattering of dust that has occurred from the device to be measured.

The present invention has been made in response to such conventional circumstances, and does not require a large-scale facility such as a clean room, and can accurately and quantitatively measure the amount of dust generated in the operating state of the measured object. The present invention is intended to provide a method for measuring the amount of dust generated.

[Configuration of Invention] (Means for Solving Problems) That is, the dust generation amount measuring method of the present invention is used for measuring the amount of dust generated from an object arranged in a clean room used in a semiconductor manufacturing process. The object to be measured is installed in a container equipped with a filter for producing a clean gas in the upper part and a bell mouth reducer in the lower part to be isolated from the outside air, and is introduced into the container through the filter, and the bell mouth A clean gas, which is discharged from above through the reducer and goes downward, is passed through and a suction pipe is installed at the lower part of the container so that the flow velocity of the gas around the collection pipe and the flow velocity of the collected gas become almost equal. Then, at least a part of the gas that has passed through the container is sampled, and the amount of dust in the gas sampled by the sampling tube is measured.

(Operation) In the dust generation amount measuring method of the present invention, the object to be tested is provided in the container to be isolated from other dust-generating objects, and is cleaned from the upper part to the lower part in the measurement chamber. Form a gas stream.
Then, for example, dust generated from the measured object in the operating state is collected together with a part of the flowing gas from the exhaust pipe,
Measure the dust count.

Therefore, it is not affected by the dust generated from other dust generators, and the dust is efficiently collected from the exhaust pipe, etc., so that a large-scale facility such as a clean room is not required and the dust is accurately generated. The quantity can be measured.

(Embodiment) An embodiment of the dust generation amount measuring method of the present invention will be described below with reference to the drawings.

The measuring 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 is formed into a cylindrical shape with an inner diameter of, for example, 300 mm to 500 mm and a height of, for example, 200 mm to 400 mm. It is configured to be visible.

A holding mechanism 1a for holding the object to be measured 2 is arranged in the measuring chamber 1. This holding mechanism 1a preferably has a shape that does not disturb the gas flow in the measurement chamber 1, and a stainless round bar with a mirror finish of about 8 mm in diameter is 80 m long.
Two are arranged at intervals of about m,
This stainless steel round bar is grounded at earth 1a.

Furthermore, the measurement chamber 1 is configured so that the purified gas passes through the measurement chamber 1. That is, the introduction pipe 4 formed of a flexible duct or the like is connected to the upper portion of the measurement chamber 1 via the filter storage chamber 3. This introduction pipe 4
Is connected to an air blower such as a blower 6 whose air blow rate is variable by a sliderac 5. The filter housing chamber 3 has, for example, a cross section of 200 mm on a side.
It has a square shape or the like of about 400 mm, a pre-filter 3a is arranged in the upper part, and an ultra-high performance air filter 3b such as a ULPA filter is arranged in the lower part.
It is preferable that the filter accommodating chamber 3, the pre-filter 3a, and the ultra-high performance air filter 3b have a size and a shape such that a cleaning gas can be blown to the entire DUT 2.
Any type of filter may be used as long as it can remove dust to be measured to almost zero while the object to be measured 2 does not move, and a purified gas can be obtained.

A measurement system capable of accurately and quantitatively measuring dust generated in the DUT 2 is disposed below the measurement chamber 1. That is, the exhaust pipe 8 is connected via the bellmouth reducer 7. Inside this exhaust pipe 8, a sampling pipe 10 connected to a light scattering type particle counter 9 is arranged,
On the downstream side of the pipe where the sumplink pipe 10 is arranged,
For example, orifice 11a and pressure gauge (digital manometer) 1
A flow rate measuring means consisting of 1b etc. is arranged.

The bell mouth reducer 7 is made of, for example, a stainless steel plate having a mirror finish as shown in FIG. 2, the bell mouth reducer 7 is grounded to the earth 7a, and the total length a is 300 mm, for example. Inner diameter b is 100 mm to 400 mm
The diameter c of the opening end is about 1.6 times as large as the inner diameter b, and the Rs of the regions indicated by reference signs d, e, f, and g in the drawing are 0.2, 0.33, 0.2, and 0.305, respectively. It has a shape in which a plurality of doubled types of R are combined, and for example, a gas flow from the measurement chamber 1 having an inner diameter of about 1.6 times the inner diameter b is turbulent in the exhaust pipe 8. It is configured to squeeze without letting go. That is, if a turbulent flow or the like occurs here, the dust becomes stagnant or biased, or new dust is generated, which makes it difficult to accurately measure the amount of dust generated from the measured object.

The sampling tube 10 is made of urethane or the like that has been subjected to antistatic treatment, and its tip is formed in a cylindrical shape from stainless steel or the like having a mirror finish as shown in FIG. The tubular member 10a is arranged.

The tubular member 10a has a total length h of, for example, about 50 mm, and has an outer shape i at the tip and a wall thickness j of 6.8 mm and 0.15 mm, respectively. The thickness 1 is 8.0 mm and 0.2 mm, respectively, and the tip end is formed in a tapered shape with a small diameter and a thin wall. That is, the turbulent flow is not generated in the sampling tube 10 and its tip when collecting dust. This tubular member 10a is
This is for collecting a part of this gas without disturbing the gas flow from the measurement chamber 1. In addition, the sampling tube
Reference numeral 10 also gradually extends obliquely downward in the exhaust pipe 8 over a distance of about 800 mm and is led out from the wall of the exhaust pipe 8 to prevent turbulent flow from occurring in the gas sampling portion.

In addition, the position of the tubular member 10a is a mechanism that can be adjusted vertically and horizontally so that it can be selected appropriately. Then, the tubular member 10
a and a sampling pipe 10 to exhaust a part of the gas to the exhaust pipe 8
It is led out to the outside and the amount of dust is counted by the light scattering type particle counter 9. The light-scattering type particle counter 9 is provided with a suction mechanism for effectively introducing dust.

As shown in FIGS. 4 and 5, the tubular member 10a at the tip of the sampling tube 10 has a shape in which the tip has a certain radius R or is gradually expanded toward the opening end. It may have a shape or the like.

Next, the method of this embodiment using the apparatus having the above configuration will be described. In the measurement chamber 1, the DUT 2 that has been pretreated by wiping with a non-dusting non-woven fabric or blowing a cleaning air is placed, and the operation of the DUT 2 is stopped first. As a result, the blower 6 is actuated, purified air or the like is introduced into the measurement chamber 1, and a preparatory operation is performed for a predetermined period. After the steady state is reached, the number of dust particles in the purified air collected by the sampling tube 10 is measured by the light scattering type particle counter 9. Although suction is performed from the sampling tube 10, the sampling tube 10 tip is arranged so that the flow of the sampling air does not change direction at the sampling tube 10 tip, and the flow rate of the sampling air is The amount of air blown by the blower 6 and the cylindrical member at the tip of the sampling pipe 10 so that the flow velocity of the air flowing through the surrounding exhaust pipe becomes almost equal.
It is preferable to adjust the inner diameter of 10a and the suction amount.
In this state, first remove the dust adhering to the DUT 2,
The state where the number of dust measured by the light scattering type particle counter 9 is almost zero is confirmed and the background cleanliness is determined. Then, the DUT 2 is operated, and the number of dusts generated when the motion mechanism is moved under a predetermined condition is measured and used as the cleanliness during the motion. This measurement is preferably performed at a plurality of positions by moving the position of the tubular member 10a at the tip of the sampling pipe 10 in the cross-sectional direction within the exhaust pipe. The amount of dust generated from the movement mechanism is obtained by subtracting the background cleanliness from the cleanliness during this movement, and further measuring the flow rate of the gas flowing into the measurement chamber 1 and performing unit conversion, the measured object 2 The total amount of dust from can be calculated.

When the amount of dust generated from a moving mechanism such as a motor is measured, the operation of the DUT 2 is such that a driving unit, a heater and the like are housed in the measurement chamber 1 and a through hole provided on the side wall of the measurement chamber 1 is used. Pull out the power cable and control cable from 1b. Further, the gap between the power cable, the control cable and the like and the through hole 1b is sealed with silicone or the like to prevent the entry of outside air.

Further, when measuring the amount of dust generated only from the target motion mechanism excluding the drive unit such as the motor, the drive unit such as the motor 2a is arranged outside the measurement chamber 1 as shown in FIG. The motor 2a and the movable part of the DUT 2 are connected by a shaft 2c loosely inserted in the hole 1b. In such a case, the gap formed between the periphery of the shaft 2c and the through hole 1b is sealed with magnetic fluid or the like.

That is, in the method of this embodiment, the DUT 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 the exhaust pipe 8 connected to the lower part of the measurement chamber 1 via the bellmouth reducer 7, and can collect dust efficiently without disturbing the gas flow, and is usually outside the clean room. The amount of dust generated from a desired measurement site can be accurately measured even in an atmosphere or the like.

Furthermore, the dust generated from the DUT 2 may be electrostatically charged and adhere to the DUT 2 or disturb the air flow.
This phenomenon is remarkable when the DUT 2 is made of an insulator. As a countermeasure against such static electricity, it can be improved by disposing the static eliminator 20 on the outflow side of the filter 3 as shown in FIG. 6, and more accurate measurement can be performed.

This static eliminator may be a known one, for example, FIG. 7 (A).
As shown in FIG. 5, a plurality of sets of discharge columns 72 are formed by 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 charge eliminating electrode 74 having a row of discharge needles 73 in the middle, and a ground electrode 75, which sandwiches this charge eliminating electrode 74,
The discharge column 72 is formed by providing 76. The discharge column 72 has a structure in which, for example, the static elimination electrode 74 and the ground electrodes 75 and 76 are located at the apexes of a triangle. The earth electrodes 75 and 76 are made of mirror-polished stainless steel rods having a diameter of, for example, about 8 mm, but the static elimination electrode 74 has a diameter of, for example, 5 m as shown in FIG. 7 (B).
A large number of discharge needles 73 are electrically connected to a stainless rod 77 of about m in a row, the tip of the discharge needle 73 is exposed, and an insulating resin coating 78 is provided so as to cover the stainless rod 77. 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 silicone resin, foamed resin, or the like, but is configured such that a cylindrical resin is cut in the longitudinal direction and the 73 rows of the discharge needles are used for handing.

By disposing the static eliminator 20 having such a configuration, it is possible to measure the amount of dust generated by the clean gas in which static electricity is removed. This can be achieved by generating a discharge between the metal discharge needle 73 of each discharge column 72 and the stainless steel rods 75 and 76. Furthermore, in order to perform more accurate measurement, the static elimination device 22 is provided in the inlet side tube 21 of the light scattering type particle counter 9 to further enhance the effect.

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

That is, the metal discharge needle is insulated from the container 81 having the ground electrode 84 at the bottom portion 82 in each cylindrical conductive container 81 with one side opening.
Discharge vessel constructed by arranging 83 in a row at a predetermined interval
A plurality of 85, for example, 3 are arranged at the positions of the vertices of a triangle.
When the inlet side tube 21 is arranged in the triangle thus configured, the static electricity charged on the inner wall of the inlet side tube 21 is
By neutralizing and removing the static electricity charged on the outer wall of 21, it can be neutralized and removed by the electrostatic effect. This static electricity removing action can be achieved by causing a corona discharge between the container 85 having the ground electrode 84 and the discharge needle 83 to generate an ion pair.

As shown in FIG. 6, the measurement result measured by the light-scattering type particle counter 9 is subjected to arbitrary data processing by the computer 30, and is printed out by the printer 31 in a desired data form. be able to. In addition, the motor 2a includes a control unit 40 and a CPU board 4
1, the disk unit 42, the CRT 43, etc. can be connected to perform desired control.

[Effects of the Invention] As described above, the dust generation amount measuring method of the present invention does not require a large-scale facility such as a clean room, and the generated dust does not adhere to the object to be measured, piping, etc. It is possible to accurately and quantitatively measure the amount of dust generation without entrainment of other dust or scattering of actual dust.

[Brief description of drawings]

FIG. 1 is a block diagram showing a dust generation amount measuring apparatus used in an embodiment method of the present invention, FIGS. 2 and 3 are partially enlarged sectional views showing essential parts of FIG. 1, FIG. 4 and FIG. FIG. 5 is a partially enlarged sectional view showing a modified example of FIG. 3, FIG. 6 is an explanatory view of another embodiment of FIG. 1, and FIGS. 7 and 8 are structural explanations of the static eliminator of FIG. It is a figure. 1 ... Measuring room, 1a ... Ground, 2 ... Object to be measured, 3 ...
Filter chamber, 4 ... Introduction piping, 6 ... Blower, 7 ...
… Bellmouth reducer, 7a… Earth, 8 …… Exhaust pipe, 9 …… Light scattering type particle counter, 10 …… Sampling tube.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Imafuku 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Within Taisei Corporation (56) Reference JP-A-58-90144 (JP, A) JP-A-SHO 58-80560 (JP, A) JP 60-185138 (JP, A) Actual opening 61-91152 (JP, U) Actual opening Sho 58-7858 (JP, U) Actual opening Sho 59-43770 (JP, U)

Claims (6)

[Claims] 1. When measuring the amount of dust generated from an object placed in a clean room used in a semiconductor manufacturing process, an object to be measured, a filter for generating a clean gas in the upper part, and a bell mouth in the lower part. It is provided in a container equipped with a reducer to be isolated from the outside air, and a clean gas which is introduced into the container through the filter and which is introduced through the bell mouth reducer and goes downward is passed therethrough. The sampling pipe provided at the lower part sucks the gas around the sampling pipe so that the flow velocity of the gas is almost equal to the flow velocity of the sampled gas, and at least a part of the gas passing through the container is sampled. A method for measuring the amount of dust, characterized by measuring the amount of dust in the gas collected by. 2. The sampling position of the gas which has passed through the container provided with the object to be measured, is performed a plurality of times at different positions in the pipe of the gas flow path. The method for measuring the amount of dust generation described. 3. The dust generation amount measuring method according to claim 1, wherein the gas introduced into the container provided with the object to be measured is a gas that has passed through a static eliminator for removing static electricity. 4. A part of the gas that has passed through the container is collected from a container provided with an object to be measured, and all pipes through which the collected gas passes are subjected to static electricity removal treatment. The method for measuring the amount of dust generation according to the first section. 5. A flow path for a clean gas flow flowing in a container provided with an object to be measured is constructed so as not to easily generate turbulent flow. Dust amount measurement method. 6. The method for collecting the gas having passed through the container provided with the object to be measured is performed so that the suction inlet for sampling does not change the flow direction of the gas.
The method for measuring the amount of dust generation described in the item.