JPH10185795A - Fine particle measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine particle measurement device which can measure fine particles sticking to a sample surface with high precision easily. SOLUTION: A single frequency signal transmitted from a signal generator 19 is amplified with a high frequency amplifier 18, and then inputted an ultrasonic wave oscillator 17. The oscillation of the oscillator 17 is further amplified with a horn 16, and transferred to an oscillation plate 14 through a resonance rod 15, so that an ultrasonic wave is generated at the oscillation plate 14. The ultrasonic wave is reflected on a convergence direction converter 13, and converges at one point on the surface of a sample S. Thanks to compression wave effect formed with ultrasonic wave, fine particles remaining on the surface are peeled off, and introduced, while on a clean air flow, into a fine particle counter 11, for measurement of particle numbers for each particle size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine particle measuring apparatus for measuring (for example, counting) fine particles such as dust adhering to the surface of a measurement sample.

[0002]

2. Description of the Related Art Semiconductor wafers, liquid crystal glass,
It is necessary to keep the surfaces of jigs (for example, wafer carriers, glass molds, etc.) used in manufacturing them clean.

[0003] A peeling means using airborne ultrasonic waves is known as a means for peeling off fine particles adhered in order to keep the surfaces of these parts, members, jigs and the like clean. On the other hand, a particle counter is known as a means for quantitatively grasping particles in the air such as a clean room.

[0004]

On the basis of these, it is conceivable to count the number of fine particles adhering to a wafer or the like and quantify the degree of cleanliness. However, in the case of a fine particle peeling unit that irradiates ultrasonic waves in air, accurate counting is difficult even if the separated fine particles are simply counted by a fine particle counter. That is, if fine particles generated from a diaphragm, a focusing direction converter, or the like constituting the fine particle separating means, or fine particles in the air brought in from the outside of the means are mixed, a measurement error occurs. Further, it is difficult to efficiently guide only the fine particles separated from the sample to the fine particle counter by the introduced clean air.

[0005] The present invention has been made in view of the above points, and it is an object of the present invention to provide a fine particle measuring apparatus capable of accurately measuring fine particles attached to a sample surface.

[0006]

According to the present invention, there is provided a fine particle measuring apparatus which irradiates a measurement sample with ultrasonic waves in the air to separate fine particles on the surface of the sample, and an air introducing means provided in the means. And an air deriving means for guiding the separated fine particles to the fine particle counter by the introduced air, and an exhaust means for discharging excess air to the outside of the separating means.

In such a particle measuring apparatus, an air introducing means and a lead-out means to a particle counter are provided in the particle separating means, and an exhaust means is additionally provided.

The peeling means has a case cover screwed to the base for maintenance of the inside, and the like.
It is removable. With the introduction of clean air, air from the outside is sucked and guided into the peeling means, and when the fine particles in the air are measured, an error occurs. Therefore, it is important to prevent this trouble. Of course, at the time of measurement, the diaphragm and the like are pre-cleaned, but it is difficult to prevent air from entering from outside. If the base portion and the case cover are brought into close contact with each other in order to prevent air from entering from outside, there is a problem that it is difficult to balance clean air and the amount of air introduced into the particle counter.

Therefore, in the present invention, an exhaust means is provided. And, for example, 50 L / min of clean air
, And 20 L / min is exhausted from the exhaust means, and the pressure inside the peeling means is constantly increased. This prevents the ambient air from being introduced into the peeling means. 30 L / min is led to the counter. By this clean air, only the fine particles from the sample surface are efficiently guided to the fine particle counter. This clean air amount is an example.

In the present invention, it is preferable that a partition is provided in the peeling means and a vent is provided. The reason why the partition and the vent are provided is to reduce the volume of the space to be kept clean.

[0011]

FIG. 1 is a block diagram of a particle measuring apparatus according to an embodiment. The fine particle peeling means 1 comprises a base 2 and a case cover 3, both of which are connected by, for example, screws. Clean air (for example, air obtained by filtering the air through a filter) is introduced at a rate of, for example, 50 L / min from the inflow port 4 above the case cover 3.

In the peeling means 1, an ultrasonic focusing direction converter 13 made of a curved plate of acrylic or the like is provided. The focusing direction converter 13 is connected to the sample contact port 8.
Is arranged so as to face the corresponding contact port 8 and is curved such that the surface facing the sample contact port 8 is concave.

The diaphragm 1 is located above the center of the sample contact port 8.
4 are installed. A vibrator 17 is connected to the diaphragm 14 via a resonance rod 15 and a horn 16. The diaphragm, the resonance rod, and the horn are made of, for example, titanium or duralumin.

An opening 5 is provided in the base portion 2 and a hopper 6 having a shape narrowing downward from a peripheral portion of the opening 5.
Is provided. A short cylindrical portion 7 is provided at the lower end of the hopper 6.
The lower end of the cylindrical portion 7 serves as a sample contact port 8. An O-ring (not shown) is attached to the lower end surface of the sample contact port 8, and the peeling means 1 is pressed against the fixed sample S to be in close contact with the surface of the sample S, and the surface of the sample S It is configured not to scratch.

A fine particle counter 11 from which air is introduced from the hopper 6 through a pipe 10 at a rate of, for example, 30 L / min is provided. This particle counter 1
As 1, various types such as a light scattering type can be used.

The peeling means 1 has an excess air outflow valve 12
Is provided, and air flows out at a rate of, for example, 20 L / min.

Next, a mechanism for irradiating the surface of the sample S with ultrasonic waves will be described.

A single frequency (around 20 kHz) transmitted from a signal generator (function synthesizer) 19
Are amplified by the high-frequency amplifier 18 and input to the ultrasonic vibrator 17 (for example, a bolted Langevin vibrator). 30 is an oscilloscope and 31 is a wattmeter.
The oscilloscope 30 is for observing the waveform of the ultrasonic wave, and is not always necessary.

The vibration of the vibrator 17 is further amplified by the horn 16, transmitted to the diaphragm 14 via the resonance rod 15, and the diaphragm 14 generates an ultrasonic wave. This ultrasonic wave has a sound pressure level of 160 dB or more. The ultrasonic waves are reflected by the focusing direction converter 13 and focused at one point on the surface of the sample S. As a result, a strong ultrasonic sound field is formed at the focal point. Fine particles remaining on the surface are peeled off by the compression wave effect formed by the ultrasonic waves. The separated fine particles are introduced into the fine particle counter 11 by the flow of clean air supplied from the upper part of the apparatus. In the particle counter 11, for example, particles having a particle diameter of 0.3 to 5 μmφ are classified and measured.
The number of particles is different for each particle size (for example, 0.3 μm or less, 0.3 to
0.5 μm, 0.5-1 μm, 1-2 μm, 2-5 μ
m, 5 μm or more).

As described above, according to the apparatus of this embodiment, since the pressure in the peeling means 1 is constantly increased, the introduction of air from the outside is prevented, and the attached fine particles on the surface of the sample S can be easily and accurately measured. . If necessary, the number of adhered particles in a required range on the surface of the sample S can be counted by moving the peeling means 1 and the sample S to each other or one of them. By doing this,
Even if the sample S is large, there is no need to cut it, and workability and measurement accuracy are excellent.

In this embodiment, the inside of the peeling means 1 is divided into an ultrasonic wave generation chamber 21 and a horn installation chamber 22 by a partition wall 20, and both chambers are circulated by a vent 23. . The resonance rod 15 is inserted through an opening 24 provided in the partition 20. The horn 16 is supported by an L-shaped stopper plate 25 provided in the horn installation room 22.

As described above, by making the volume of the measurement chamber 21 smaller than the entire volume in the casing 1 by the partition wall 20, it is allowed to flow into the peeling means 1 to maintain the atmosphere in the measurement chamber 1 at a required cleanliness. It is possible to reduce the amount of clean air inflow required for the vehicle.

[0023]

According to the fine particle measuring apparatus of the present invention, since the ultrasonic wave is applied, only the fine particles can be peeled off in a non-contact manner. The attached fine particles can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a particle measuring device according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fine particle peeling means 2 Base part 3 Case cover 6 Hopper 7 Cylindrical part 8 Sample contact port 11 Fine particle counter 13 Focusing direction converter 14 Vibrating plate 15 Resonant rod 16 Horn 17 Ultrasonic transducer

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Ryohei Miwa 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Kurita Industry Co., Ltd.

Claims (1)

[Claims] 1. A fine particle peeling means for irradiating a measurement sample with ultrasonic waves in the air to separate fine particles on the surface of the sample, an air introducing means provided in the means, and a fine particle counter for separating the separated fine particles by introduced air. And a discharge means for discharging excess air to the outside of the separation means.