JPH08320293A - Method and device for inspecting foreign matter - Google Patents

Abstract

PURPOSE: To provide a foreign matter inspecting device which is free from the erroneous detection of foreign matter by bubbles in a liquid. CONSTITUTION: This foreign matter inspecting device has a storing tank 1 in which a liquid such as cleaning solvent L1 is stored, and a sample liquid tank 3 allowed to communicate with the storing tank 1 to introduce a part of the liquid in the storing tank 1. An inspecting duct 7 opened to introduce the liquid is provided on the bottom surface of the sample liquid tank 3, and a valve 8 for opening and closing the passage of the fluid in the inspecting duct 7 is mounted on the inspecting duct 7. A foreign matter detector 11 for detecting a foreign matter in the liquid carried in the inspecting duct 7 is set in the middle of the inspecting duct 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter inspection method and apparatus, and more particularly to a technique effectively applied to the detection of foreign matter existing in a liquid.

[0002]

2. Description of the Related Art For example, in the manufacture of semiconductor devices, a wide variety of liquids such as pure water and hydrochloric acid as cleaning materials, resists and various organic solvents as photoprocessing materials, and various acids as etching materials are used. ing. If there is a foreign substance in such a liquid, the surface of the semiconductor wafer is contaminated and the characteristics of the formed element are changed, and the completed semiconductor device does not have the desired performance. In this method, foreign substances in the liquid are inspected as well as foreign substances are removed by a filter.

It is considered that the foreign matter in the liquid is inspected by immersing one side of the nozzle in a liquid to be inspected, sucking it with a cylinder, introducing the liquid into a measuring instrument, and scattering light by a laser. As an example that describes such foreign matter inspection in detail, for example, published by the Industrial Research Committee, “Electronic Material Separate Volume / VLSI Manufacturing, Test Equipment Guidebook”, 1994 edition (November 20, 1993), P161 There is ~ P162.

[0004]

In many cases, the liquid is heated in the liquid storage tank so that the liquid most efficiently acts on the workpiece such as a semiconductor wafer to be processed. Then, in such a case, bubbles are generated in the liquid.

If foreign matter in the liquid is inspected by using the above-mentioned technique in the presence of bubbles, the measuring instrument will erroneously detect bubbles as foreign matter. This is not desirable because the foreign matter in the liquid cannot be accurately measured.

Therefore, an object of the present invention is to provide a technique capable of performing an accurate foreign matter inspection without erroneously detecting a foreign matter due to bubbles in a liquid.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

That is, the foreign matter inspection method according to the present invention is
A part of the liquid to be inspected is extracted, and this is left for a predetermined time to remove air bubbles in the liquid, and then the foreign substance in the liquid is inspected while flowing the liquid.

Further, the foreign matter inspection apparatus according to the present invention has a liquid storage tank in which a liquid is stored, and a sample liquid tank which is in communication with the liquid storage tank and into which a part of the liquid in the liquid storage tank is introduced. are doing.
An inspection duct that opens into the bottom surface of the sample liquid tank and into which a liquid is introduced is provided, and a valve that opens and closes a fluid passage in the inspection duct is attached to the inspection duct. Foreign matter detecting means for detecting foreign matter in the liquid flowing in the inspection duct is installed in the middle of the inspection duct.

In such a foreign matter inspection apparatus, it is desirable to use a flow rate adjusting valve capable of adjusting the flow rate of the liquid as the valve. In addition, an air suction means for sucking the air in the tank may be attached to the sample liquid tank. Further, a liquid suction means for sucking the liquid in the sample liquid tank may be attached to the inspection duct.

[0012]

According to the above-mentioned means, the sampled liquid to be inspected is left in the sample liquid tank for a predetermined time to remove the air bubbles, and then the foreign matter detection means performs the foreign matter inspection. There is no possibility of being erroneously detected as a foreign substance, and it becomes possible to accurately measure the foreign substance in the liquid.

Further, by using the flow rate adjusting valve, the flow rate of the liquid flowing in the inspection duct can be controlled and the desired amount of sampling can be performed.

By using the air suction means, it becomes possible to forcibly remove bubbles even when the inspection object is a highly viscous liquid.

By using the liquid suction means, it is possible to forcibly introduce the liquid into the inspection duct in the foreign matter inspection of the highly viscous liquid, so that the foreign matter inspection can be performed promptly.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same members are designated by the same reference numerals, and the repeated description thereof will be omitted.

(Embodiment 1) FIG. 1 is a schematic view showing a foreign matter inspection apparatus which is an embodiment of the present invention.

The foreign matter inspection apparatus of this embodiment detects foreign matter contained in a cleaning liquid (liquid) L1 used for cleaning the surface of a semiconductor wafer (not shown) in the manufacture of semiconductor devices, for example. Shows the liquid storage tank 1 in which the cleaning liquid L1 is stored. The liquid storage tank 1 is connected to the sample liquid tank 3 via a feed pipe 2. And the storage tank 1
In order to introduce a part of the cleaning liquid L1 therein into the sample liquid tank 3 as a sample, a feed pump 4 is provided in the middle of the feed pipe 2. The cleaning liquid L1 contained in the sample liquid tank 3 is once stored and then the foreign matter is measured.

The sample liquid tank 3 has an exhaust duct 6 that is attached to the filter 5 and opens on the upper surface thereof. Therefore, the cleaning liquid L1 introduced causes the air in the sample liquid tank 3 to be pushed out from the exhaust duct 6, and the ingress of dust from the outside is blocked by the filter 5.

An inspection duct 7 is provided which opens at the bottom of the sample liquid tank 3 and serves as a flow path when the cleaning liquid L1 in the tank naturally drops. The inspection duct 7 is provided with a valve 8 for opening and closing the flow path of the cleaning liquid L1 in the inspection duct 7. When the valve 8 is opened, the cleaning liquid L1 passes from the sample liquid tank 3 to the outside through the inspection duct 7. Is discharged. This valve 8 is a flow rate adjusting valve whose opening degree can be adjusted. By setting the opening degree of the valve 8 to a desired degree, the flow rate of the cleaning liquid L1 flowing through the inspection duct 7 can be freely adjusted. ing. A valve that does not have a flow rate adjusting function and can only open and close the flow path may be used.

The sample liquid tank 3 is further provided with a drain 9 having an opening at its bottom surface. A drain cock 10 is attached to the drain 9, and the cleaning liquid L1 remaining in the sample liquid tank 3 after the foreign matter inspection is discharged from the drain 9.

A foreign matter detector (foreign matter detecting means) 11 for detecting foreign matter in the cleaning liquid L1 falling in the inspection duct 7 is installed in the middle of the inspection duct 7. The foreign matter detector 11 is a light emitting unit 11a for irradiating the cleaning liquid L1 with the laser Z, and a photomultiplier which is a light receiving unit for the laser Z provided across the inspection duct 7 from the light emitting unit 11a. 11b. Then, the photomul 11b receives the scattered light of the laser Z scattered by the foreign matter in the cleaning liquid L1, and the foreign matter is counted. The photomultiplier 11b includes an amplifier 1 for amplifying an electric signal generated corresponding to the received laser Z.
2 is connected.

With such a foreign matter inspection apparatus, the cleaning liquid L
The foreign matter in 1 is measured as follows.

First, the feed pump 4 is operated to introduce an appropriate amount of the cleaning liquid L1 in the storage tank 1 to be inspected into the sample liquid tank 3 as a sample. At this time, the extracted cleaning liquid L1 is heated to 75 to 80 ° C. in the liquid storage tank 1, and bubbles are generated due to this. The cleaning liquid L in the sample liquid tank 3
Valve 8 and drain cock 1 so that 1 does not flow out
0 means the closed position.

Next, the cleaning liquid L1 is left in the sample liquid tank 3 for a predetermined time, for example, about 1 minute. As a result, the bubbles in the cleaning liquid L1 rise and are taken up by the air in the tank and removed from the cleaning liquid L1. The leaving time can be freely set in consideration of the type of liquid to be inspected and the degree of generation of bubbles.

After removing the air bubbles, the valve 8 is opened and the cleaning liquid L1
The foreign matter detector 11 while letting it fall naturally from the inspection duct 7
To measure foreign matter in the liquid. The valve 8 is adjusted in its opening degree to control the flow rate of the cleaning liquid L1, and to control the measuring time and the measuring amount so as to sample a desired amount. When foreign matter in the liquid is present, the laser Z from the light projecting unit 11a is scattered and received by the photomultiplier 11b, and this is detected by the electric signal generated by such scattered light. Here, as described above, since the bubbles in the cleaning liquid L1 are removed in the sample liquid tank 3, the bubbles do not intervene as the scattering factor of the laser Z, and the scattered light is entirely foreign matter.

When the foreign matter inspection is completed, the valve 8 is closed and the drain cock 10 is opened to drain the cleaning liquid L1 remaining in the sample liquid tank 3 from the drain 9.

As described above, according to the foreign matter inspection apparatus of the present embodiment, the sampled cleaning liquid L1 is left in the sample liquid tank 3 for a predetermined time to remove air bubbles, and then the foreign matter detector 11 measures foreign matter. Since the bubbles are erroneously detected as foreign matter, it is possible to accurately measure the foreign matter in the liquid.

(Embodiment 2) FIG. 2 is a schematic view showing a foreign matter inspection apparatus which is another embodiment of the present invention.

The foreign matter inspection apparatus according to this embodiment is used for foreign matter inspection of a highly viscous liquid such as the resist L2, and in order to suck the air in the sample liquid tank 3 and to actively exhaust it. The exhaust pump (air suction means) 13 of the sample liquid tank 3 is attached via the exhaust duct 6.
The foreign matter inspection apparatus according to the first embodiment is different in that a suction pump (liquid suction means) 14 for sucking the resist L2 therein is attached to the inspection duct 7.

In the case of a highly viscous liquid such as the resist L2, it is difficult to remove the air bubbles by simply leaving it in the sample liquid tank 3. Therefore, the exhaust pump 13 is used for forced removal. . Similarly, the resist L2
In this case, since there is a possibility that the resist L2 having the intended flow rate will not flow through the inspection duct 7 simply by opening the valve 8, the suction pump 14 may suck the resist L2 to obtain a desired flow rate. It is what

It should be noted that it is possible to perform a foreign matter inspection of a low-viscosity liquid such as the cleaning liquid L1 (Embodiment 1) by the foreign matter inspection apparatus having such a configuration. In this case, the cleaning liquid L1 is forcibly introduced into the inspection duct 7 instead of being naturally dropped. Further, the exhaust pump 13 in the present embodiment
Only one of the suction pump 14 and the suction pump 14 can be attached.

In this foreign matter inspection apparatus, when the exhaust pump 13 is operated, the liquid level of the resist L2 stored in the sample liquid tank 3 slightly rises, and the bubbles in the resist L2 are forcibly removed in a short time. To be done. After removing air bubbles, valve 8
Open the suction pump 14 and open the resist L
Foreign matter detector 1 while sucking 2 and flowing it into inspection duct 7
Foreign matter measurement is performed at 1.

As described above, according to the foreign matter inspection apparatus of this embodiment, the bubbles in the highly viscous liquid such as the resist L2 are removed by using the exhaust pump 13 and the suction pump 14 is forcibly inspected. Since the duct 7 is passed through, it is possible to stably perform the foreign matter inspection regardless of the degree of viscosity.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in each of the embodiments, the cleaning liquid L1 and the resist L2 are applied as the liquid to be inspected, but the liquid is not limited to these, and liquids other than those used in the semiconductor device manufacturing process are included. It is possible to apply various other liquids.

[0037]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) That is, according to the foreign matter inspection technique of the present invention, the sampled liquid to be inspected is left in the sample liquid tank for a predetermined time to remove air bubbles, and then the foreign matter detection means performs the foreign matter inspection. Since the bubbles are erroneously detected as foreign matter, it is possible to accurately measure the foreign matter in the liquid.

(2) Also, by using a flow rate adjusting valve as the valve, it becomes possible to control the flow rate of the liquid flowing in the inspection duct, and it is possible to sample a desired amount.

(3). By using air suction means,
It is possible to forcibly remove bubbles even when the inspection target is a highly viscous liquid.

(4) By using the liquid suction means, in the foreign matter inspection of a highly viscous liquid, the liquid can be forcibly introduced into the inspection duct, and the foreign matter inspection can be performed promptly. become.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a foreign matter inspection device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a foreign matter inspection device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Storage Tank 2 Feeding Pipe 3 Sample Liquid Tank 4 Feeding Pump 5 Filter 6 Exhaust Duct 7 Inspection Duct 8 Valve 9 Drain 10 Drain Cock 11 Foreign Substance Detector (Foreign Substance Detecting Device) 11a Light Emitting Unit 11b Photomal 12 Amp 13 Exhaust pump (air suction means) 14 Suction pump (liquid suction means) L1 Cleaning liquid (liquid) L2 Resist (liquid) Z Laser

Claims (5)

[Claims] 1. A part of a liquid to be inspected is extracted, left for a predetermined time to remove air bubbles in the liquid, and then foreign matter in the liquid is inspected while flowing the liquid. Foreign material inspection method. 2. A liquid storage tank in which a liquid is stored, a sample liquid tank in communication with the liquid storage tank, into which a part of the liquid in the liquid storage tank is introduced, and a bottom surface of the sample liquid tank. An inspection duct that is provided with an opening and into which the liquid is introduced, a valve that is attached to the inspection duct and that opens and closes a fluid passage in the inspection duct, and the inspection duct that is installed in the middle of the inspection duct. A foreign matter inspection device, comprising: a foreign matter detecting means for detecting a foreign matter in the liquid flowing inside. 3. The foreign matter inspection apparatus according to claim 2,
The foreign matter inspection apparatus is characterized in that the valve is a flow rate adjusting valve capable of adjusting a flow rate of liquid. 4. The foreign matter inspection apparatus according to claim 2 or 3, wherein the sample liquid tank is provided with an air suction means for sucking air in the tank. 5. The foreign matter inspection apparatus according to any one of claims 2 to 4, wherein the inspection duct is provided with a liquid suction means for sucking the liquid in the sample liquid tank. Foreign matter inspection device.