TWI648812B - Mini environment device - Google Patents

Abstract

The present invention provides a mini-clean device capable of reliably and quickly removing electricity from the interior of a semiconductor wafer storage container. The mini-cleaning device of the present invention has a semiconductor wafer storage container 10 in which the semiconductor wafer W is hermetically sealed, and a transfer chamber 20 in which the inside is maintained in a clean state. In the transfer chamber 20, a fan filter unit 22 that generates an air flow from above and below the transfer chamber 20, and an ion generator 24 that generates ions for removing the internals of the transfer chamber 20 and the semiconductor wafer storage container 10 are further provided. A rectifying plate 26 located above the opening A ₃ and spaced apart from the opening A3 and inclined toward the opening A ₃ . The ion generator 24 is disposed on the rectifying plate 26.

Description

Mini clean device

The present invention relates to mini clean devices. In particular, there is a mini-cleaning device that can more reliably and quickly remove the interior of the semiconductor wafer storage container.

In order to cope with contamination of semiconductor wafers by fine particles such as dust in the air, the manufacturing steps of conventional semiconductor wafers are performed in a clean room. As semiconductor devices continue to be highly integrated, pollution countermeasures have become more stringent in recent years.

In recent years, the clean room has changed from a vertical flow type in which the entire plant has become a high-definition net area to a mini-clean (local clean environment) in which a clean environment with a clearer degree of improvement than the surrounding area is provided in a small space. ) became the mainstream. In the mini-clean type, a semiconductor wafer storage container for semiconductor wafer transfer or storage such as FOUP (Front Opening Unified Pod) or FOSB (Front Opening Sipping Box) standardized by the SEMI standard is used. The semiconductor wafer storage container is generally formed of polycarbonate or the like and is easily charged, and the semiconductor wafer stored therein is also easily charged.

A device for use in such a mini-cleaning method, as disclosed in Patent Document 1, describes a mini-cleaning device which is provided near an opening portion on the inner side of the transfer chamber. An ion generator that emits ion gas toward the opening is placed. According to Patent Document 1, by disposing the ion generator in the vicinity of the opening of the transfer chamber, it is possible to remove the static gas in the semiconductor wafer storage container, and also to charge the semiconductor stored in the semiconductor wafer storage container. The wafer is de-energized.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2010-165741

However, in the mini-cleaning device described in Patent Document 1, the charge-removing of the charged semiconductor wafer stored in the semiconductor wafer storage container is not sufficient, and even if the semiconductor wafer storage container can be neutralized, it is required to be equivalent. Long time. The charging of the semiconductor wafer causes electrostatic discharge to deteriorate the semiconductor wafer, which is also a cause of malfunction or malfunction of the transport mechanism for transporting the semiconductor wafer. Therefore, it is necessary to more reliably and quickly place the semiconductor wafer inside the container. Mini-cleaning device for electricity removal.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a mini-cleaning device that can more reliably and quickly neutralize the interior of a semiconductor wafer storage container.

In order to achieve the above object, the inventors of the present invention have made various efforts to first review the flow of clean air of the fan filter unit provided at the top of the transfer chamber of the mini-cleaning device.

Therefore, the first drawing schematically shows a schematic cross-sectional view of a main part of a mini-cleaning apparatus 200 of the prior art. The mini-cleaning device 200 has a semiconductor wafer storage container 10, a transfer chamber 20, and a transfer mechanism 30. In the semiconductor wafer storage container 10, the semiconductor wafer W is hermetically sealed by an opening and closing cover, and an opening and closing portion A ₁ for loading and unloading the semiconductor wafer W is provided. The inside of the transfer chamber 20 is maintained in a clean state. The transport device 30 takes out the semiconductor wafer W from the semiconductor wafer storage container 10 and transports it to the inside of the transfer chamber 20. A portion of the side wall of the transfer chamber 20 is constructed by loading 埠L. The loading cassette L includes a mounting table L _{1 on} which the semiconductor wafer storage container 10 is placed, and a blocking mechanism L ₂ that can close the opening A ₃ that communicates with the opening and closing portion A ₁ . Further, the blocking mechanism L ₂ is located on the inner surface of the side wall of the transfer chamber 20. Further, a fan filter unit 22 (hereinafter simply referred to as "FFU22") that generates an air flow flowing from the upper side in the transfer chamber 20 to the lower side is provided on the top of the transfer chamber 20, and the FFU 22 is provided with the ion generator 24.

The details are described in the examples to be described later, but the inventors reviewed the flow direction of the mini-cleaning device 200 of the prior art by simulation and experiment. As a result, as indicated by an arrow F in FIG. 1, the airflow F generated from the FFU 22 flows from the top to the bottom as viewed from the entire inside of the transfer chamber 20 of the semiconductor wafer storage container 10. However, the inventors have confirmed that the airflow F flowing into the semiconductor wafer storage container 10 is recirculated from the bottom surface side to the upper surface side, and the wind speed flowing out into the semiconductor wafer sheet storage container 10 is relatively small. Further, when the static elimination effect was confirmed by experiments, it was confirmed that there was almost no static elimination in the semiconductor wafer storage container 10 in the mini-cleaning apparatus 200. And also confirmed that, as shown in Patent Document 1, in a mini-clean apparatus 200, even if the ion generator 24 is provided to change the opening portion to the vicinity of A _3, although the effect of improving the neutralization can be seen, but not sufficient.

The inventors of the present invention have considered that the airflow in the semiconductor wafer storage container cannot sufficiently flow in, so that ions generated by the ion generator cannot sufficiently flow into the semiconductor wafer storage container, and as a result, the static elimination in the semiconductor wafer storage container becomes insufficient. Therefore, it is conceivable to provide a rectifying plate at a predetermined position near the opening of the transfer chamber, and to mount the ion generator on the rectifying plate. As a result, it was found that the internalization of the semiconductor wafer storage container can be more reliably and quickly eliminated. this invention. That is, the main constitution of the present invention is as follows.

The mini-cleaning device of the present invention includes a semiconductor wafer storage container, and the semiconductor wafer is sealed and stored by an opening and closing cover, and an opening and closing portion for loading and unloading the semiconductor wafer is provided; and the transfer chamber is internally maintained. In the clean state, and the transport mechanism is disposed in the transfer chamber, the semiconductor wafer is taken out from the semiconductor wafer storage container and transported to the transfer chamber. A part of the side wall of the transfer chamber is composed of a loading cassette that includes a mounting table on which the semiconductor wafer storage container is placed, and a closing mechanism that can close an opening that communicates with the opening and closing portion. An occlusion mechanism is located on an inner face of the side wall of the transfer chamber. The transfer chamber is further provided with: a fan filter unit, generating a gas flow from above and below the transfer chamber; an ion generator generating ions for removing the internal of the transfer chamber and the semiconductor wafer storage container; and rectifying The plate is located above the opening, spaced apart from the opening, and disposed obliquely toward the opening. The ion generator is mounted to the rectifier plate.

Further, it is preferable that the ion generator is attached to the opening side end portion of the flow regulating plate.

Moreover, the semiconductor wafer is preferably a tantalum wafer.

According to the present invention, there is provided a mini-cleaning apparatus capable of more reliably and rapidly removing the inside of a semiconductor wafer storage container because the rectifying plate and the ion generator are disposed at appropriate positions in the transfer chamber.

10‧‧‧Semiconductor wafer storage container

11‧‧‧Open and close cover

20‧‧‧Transfer room

22‧‧‧Fan filter unit

24‧‧‧Ion generator

26‧‧‧Rectifier board

30‧‧‧Transportation agency

40‧‧‧Charging board monitor

100, 200‧‧‧ mini clean device

A ₁ ‧‧‧Opening and closing department

A ₃ ‧‧‧ openings

F‧‧‧Airflow

W‧‧‧Semiconductor Wafer

L‧‧‧Loading

L ₁ ‧‧‧ mounting table

L ₂ ‧ ‧ occlusion mechanism

Fig. 1 is a schematic cross-sectional view showing a mini-cleaning device of the prior art.

Figure 2 is a schematic view showing an outline of a mini-cleaning apparatus according to an embodiment of the present invention. To profile.

Fig. 3 is a schematic cross-sectional view showing a flow direction of a rectifying plate of a mini-cleaning apparatus according to an embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view for explaining an installation position of a rectifying plate of a mini-cleaning apparatus according to an embodiment of the present invention.

Fig. 5 is a schematic view for explaining the wind speed of the airflow in the semiconductor wafer storage container of the embodiment, (A) is a perspective view showing a measurement point of the wind speed; (B) shows the wind speed of the invention example 1; (C) The wind speed of the conventional example 1 is shown.

Fig. 6 is a schematic cross-sectional view showing the installation position of the rectifying plate and the ion generator of the embodiment, (A) showing Inventive Example 2; (B) showing Conventional Example 2; and (C) showing Comparative Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience of explanation, each of the drawings shows the aspect ratio of the constituent elements of the semiconductor wafer and the device more exaggerated than the implementation ratio. Also, because of the simplification of the schema, only the main parts of the composition are displayed in outline. For example, although the processing device for processing the semiconductor wafer W is connected to the transfer chamber 20, since it is not the main portion of the present embodiment, the drawings and description are omitted.

Fig. 2 is a schematic cross-sectional view showing the mini-cleaning apparatus 100 of the present invention. As shown in FIG. 2, a mini-cleaning apparatus 100 according to an embodiment of the present invention includes a semiconductor wafer storage container 10, a transfer chamber 20, and a transfer mechanism 30. In the semiconductor wafer storage container 10, the semiconductor wafer W is hermetically sealed by the opening and closing cover 11, and the opening and closing portion A ₁ for carrying in and carrying in the semiconductor wafer W is provided. The transfer chamber 20 is maintained in an internally clean state. The transport mechanism 30 takes out the semiconductor wafer W from the semiconductor wafer storage container 10 and transports it to the inside of the transfer chamber 20. A portion of the side wall of the transfer chamber 20 is then constructed of load 埠L. The loading cassette L includes a mounting table L _{1 on} which the semiconductor wafer storage container 10 is placed, and a blocking mechanism L ₂ that can close the opening A ₃ that communicates with the opening and closing portion A ₁ . Further, the blocking mechanism L ₂ is located on the inner surface of the side wall of the transfer chamber 20.

Here, the transfer chamber 20 is further provided with a fan filter unit 22 (hereinafter simply referred to as "FFU22"), an ion generator 24, and a rectifying plate 26. The FFU 22 generates an air flow from above in the transfer chamber 20 toward the lower side. The ion generator 24 generates ions that neutralize the interior of the transfer chamber 20 and the semiconductor wafer storage container 10. Rectifying plate 26 positioned above the opening portion of A _3, A ₃ toward the opening portion spaced from the opening portion and inclined toward A _3. The attachment of the ion generator 24 to the rectifying plate 26 is a special technical feature of the mini-cleaning device 10 of the present embodiment. With this configuration, as shown by the airflow F of FIG. 2, the ions generated by the ion generator 24 sufficiently flow into the semiconductor wafer storage container 10, so that the mini-cleaning device 100 of the present embodiment can store the semiconductor wafer. The interior of the container 10 is more reliably and quickly removed. Each structure will be described in detail below.

The semiconductor wafer storage container 10 can use a general FOUP specified by SEMI standard E47.1 or the like. The semiconductor wafer storage container 10 is provided with an opening and closing portion A ₁ for loading and unloading the semiconductor wafer W. When the sealed semiconductor wafer storage container 10, opening and closing cover 11 to close the opening and closing portion A _1. Further, the robot arm and the like is removed by opening and closing the opening and closing cover 11 is opened portion A _1. The FOUP can store a plurality of (for example, 25) semiconductor wafers W in the FOUP, and can store the semiconductor wafer W in a sealed state. Further, the portion in contact with the semiconductor wafer W of the FOUP is generally formed of polycarbonate or the like.

The load 埠L is a dielectric surface in which the semiconductor wafer W in the semiconductor wafer storage container 10 (FOUP) is sent to the transfer chamber 20, and a general loading cassette can be used. In addition, similar to FOUP, loading 埠 is also regulated by SEMI standard E154 and the like. The loading cassette L includes a mounting table L _{1 on} which the semiconductor wafer storage container 10 is placed, and a blocking mechanism L _{2 that can} close the opening A ₃ of the opening and closing portion A ₁ of the semiconductor wafer storage container. Further, a part of the side wall of the transfer chamber 20 is constituted by a load 埠L, and the closing mechanism L ₂ is located at the inner surface of the side wall of the transfer chamber 20. The semiconductor wafer storage container 10 storing the semiconductor wafer W is transported to the vicinity of the loading cassette L by a ceiling monorail or a ground traveling robot, and then placed on the mounting table L ₁ loaded with the cassette L by a robot arm or the like. For convenience of explanation, although not shown, the transfer chamber 20 is provided with a plurality of loading cassettes, and the mini cleaning apparatus 100 may be provided with a plurality of loading cassettes L.

The inside of the transfer chamber 20 is maintained in a clean state by the FFU 22 or the like. A portion of the side wall of the transfer chamber 20 is constructed by loading 埠L as previously described. And, inside the transfer chamber 20 is provided inside the conveyance mechanism 30, a shutter is provided to store opening and closing the opening and closing of the container 10. A ₁ cover 11 to semiconductor wafers, taken out of the semiconductor wafer W from the container and conveyed to the transfer chamber 20 .

The closing mechanism L _{2 is,} for example, a sliding door that moves up and down, and the blocking mechanism L ₂ can close the transfer chamber 20 to maintain the clean state. When the closing mechanism L ₂ opens the opening A ₃ and the opening and closing portion A ₁ is also opened, the semiconductor wafer storage container 10 and the transfer chamber 20 communicate with each other.

Further, the transport mechanism 30 can be configured by a general transport robot or the like including a robot (or a robot arm). The semiconductor wafer W stored in the semiconductor wafer storage container 10 is adsorbed or held by a robot (or a robot arm), and The semiconductor wafer W is placed in the semiconductor wafer storage container 10.

Further, the FFU 22 is composed of a blower fan, a high-performance dust filter, and the like. Further, the ion generator 24 can be a device that applies a high voltage to the discharge electrode, generates an arc discharge between the discharge electrode and the ground electrode, and generates a positive ion and a negative ion, or a photoionization device. Further, although not shown, the ion generator 24 is provided with a power supply line or the like connected to the voltage source in a range that does not affect the direction of the airflow F. Further, the frame body, the closing mechanism L ₂ , the conveying mechanism 30, the FFU 22, and the ion generator 24 of the transfer chamber 20 can be used in a general style used in a general mini-cleaning device.

Here, the patterns 100 of the present embodiment mini-clean apparatus, for opening the airflow F flows into the upper portion from the transfer chamber 20 A _3, the rectifying plate 26 is set above the transfer chamber 20. A portion of the opening _3, and The opening portion A _{3 is} spaced apart and disposed obliquely toward the opening portion A ₃ , and the ion generator 24 is attached to the rectifying plate 26 , and these features are particularly important. As shown in the outline of Fig. 3, by providing the rectifying plate 26 in the transfer chamber, the airflow F is from the semiconductor wafer storage container 10 as opposed to the case where the rectifying plate 26 is not provided (see the first drawing described above). The upper side flows into the bottom side. Further, the wind speed of the outflow into the semiconductor wafer storage container 10 can be increased from the simulations and experiments of the present inventors. As described above, in the mini-cleaning apparatus 100 of the present embodiment, the ions generated by the ion generator 24 are carried on the airflow F, and the inside of the semiconductor wafer storage container 10 can be more reliably and quickly removed.

Here, as shown in a schematic cross-sectional view of FIG. 4, the location of the rectifying plate 26, assuming the rectifying plate 26 in the horizontal direction A and the upper opening portion ₃ a distance of 1, the height is h, inclined with respect to the horizontal plane The angle is θ. If the direction of the airflow F can flow from the upper surface of the semiconductor wafer storage container 10 to the bottom surface as shown in Fig. 3, the range of 1, h, and θ can be set as follows. That is, when the shape of the flow regulating plate is a flat plate shape as illustrated, the distance l in the horizontal direction can be set to 50 mm or more, and preferably 150 mm or less. In this case, the height h can be set to 50 mm or more, and 200 mm or less is preferable. Moreover, in this case, the inclination angle θ can be set to 20 or more, and 60 or less is preferable. When the shape of the flow regulating plate is a flat plate shape as illustrated, the width L of the flow regulating plate can be set to 30 mm or more, preferably 100 mm or less. The length of the rectifying plate 26 in the longitudinal direction (not shown) may be longer than the length of the semiconductor wafer storage container 10 in the same direction, but if the direction of the airflow F as shown in Fig. 3 can be formed, even if it is relatively short does not matter.

Further, the shape of the flow regulating plate 26 is not limited to the flat plate shape shown in the drawing, and may be a semi-arc shape or a curved shape as long as the direction of the air flow F as shown in Fig. 3 can be formed. Further, the method of attaching the flow regulating plate 26 to the transfer chamber 20 can be provided in accordance with a conventional method. Although not shown, for example, a V-shaped member or the like can be provided to a part of the wall portion of the transfer chamber 20, and It is set by the beam of the transfer chamber 20. Further, in order to prevent dust from being generated in the flow regulating plate in the transfer chamber 20, it is preferable to use a lifting device or the like in a fixed manner in the transfer chamber 20 without using a lifting agent or the like. In this case, the arrangement of the rectifying plate 26 is an important condition for the removal of the semiconductor wafer W without interfering with the transfer device 30.

The ion generator 24 is attached to the rectifying plate 26, and can be arbitrarily set as long as the generated ions can flow into the semiconductor wafer storage container 10. However, the ion generator 24 is attached to the opening A ₃ side of the rectifying plate 26. The department is particularly good. Further, the ion generator 24 may be attached to the upper surface side of the rectifying plate 26.

In addition, the semiconductor wafer W to be transported as the mini-cleaning device 100 of the present embodiment may be any material. The semiconductor wafer W is, for example, a bulk single crystal wafer composed of germanium, a compound semiconductor (GaAs, GaN, SiC) and having no epitaxial layer on its surface. Further, an epitaxial wafer having an epitaxial layer on the surface of the bulk single crystal wafer can also be exemplified as the semiconductor wafer W. The semiconductor wafer in the middle of forming the device element or after the device element is formed can be transported as the object of the mini-clean device 100. Among these wafers, it is preferable to use a silicon wafer (an epitaxial wafer including an epitaxial layer formed on the surface) as the semiconductor wafer W. Because the silicon wafer is easy to carry static electricity.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

<Experimental Example 1>

(Inventive Example 1)

Prepare the mini-cleaning device 100 shown in Fig. 2. Regarding the installation position of the flow regulating plate 26, the distance 1 in the horizontal direction described in Fig. 4 is set to 65 mm, the height h is set to 60 mm, and the inclination angle θ is set to 30°. Further, the shape of the flow regulating plate 26 was set to a flat plate shape as shown, and the width L of the flow regulating plate was set to 65 mm. Further, the length of the flow regulating plate 26 in the longitudinal direction is set to be 400 mm larger than the container width of the semiconductor wafer storage container. Further, the ion generator 24 is attached to the end portion of the flow regulating plate 26 on the side of the opening A ₃ side. The center of the semiconductor wafer storage container 10 is moved from the both end portions of the opening A ₃ toward the inside of the semiconductor wafer storage container 10 by 50 mm in the vertical direction and at a position shifted by 5 mm in the horizontal direction (see FIG. 5(A) ) Set as the measurement point and set the wind direction anemometer to measure the wind speed at the measurement point. Also, a general thermal fluid analysis program is used to simulate the flow direction of the gas flow within the device. The difference from Fig. 2 is that the semiconductor wafer W is removed because a three-dimensional anemometer is provided.

As shown in Fig. 5(B), in the upper measurement point of the invention example 1, the airflow flowing from the transfer chamber 20 side into the semiconductor wafer storage container 10 at a wind speed of 0.25 m/s was observed. Further, at the lower measurement point, a wind flow from the bottom surface side of the semiconductor wafer storage container 10 to the lower side of the transfer chamber 20 was observed, and the air flow rate was 0.15 m/s. Further, as a result of the simulation, it was confirmed that the gas flow flowed in the direction indicated by the arrow F in Fig. 2 . In addition, the wind speed of the FFU 22 is set to 0.60 m/s.

(Conventional Example 1)

A mini-cleaning apparatus similar to that of Inventive Example 1 was prepared except that the rectifying plate 26 and the ion generator 24 were removed from the mini-cleaning apparatus 100 of the first embodiment. The measurement point was set at the same position as in Invention Example 1. The wind speed at the measurement point was measured in the same manner as in Inventive Example 1, and the direction of the air flow in the device was simulated.

As shown in Fig. 5(C), in the upper measurement point in the conventional example 1, the wind direction from the upper surface side of the semiconductor wafer storage container 10 toward the upper side of the transfer chamber 20 was observed, and the wind speed was 0.10 m/s. airflow. Further, at the lower measurement point, it was observed that the transfer chamber 20 side was directed toward the airflow from the bottom surface side of the semiconductor wafer storage container 10, and the air velocity was 0.15 m/s. Further, as a result of the simulation, it was confirmed that the gas flow flowed in the direction indicated by the arrow F in Fig. 1 .

As described above, in the conventional example 1, the airflow F flowing into the semiconductor wafer storage container 10 is from the bottom surface side to the upper surface side, and the wind speed flowing out into the semiconductor wafer sheet storage container 10 is relatively small. On the other hand, in the first embodiment, the airflow F flowing into the semiconductor wafer storage container 10 is opposite to the conventional example 1 in that the wind speed from the upper surface side to the bottom surface side and flowing into the semiconductor wafer storage container 10 is relatively large. .

<Experimental Example 2>

(Inventive Example 2)

A mini-cleaning apparatus similar to that of Inventive Example 1 was prepared, and as shown in Fig. 6(A), a charging-plate monitor 40 was provided on the bottom surface of the semiconductor wafer storage container 10. Further, in the same manner as in the first embodiment, the semiconductor wafer W in the semiconductor wafer storage container 10 is removed. After measuring the time when the charging pad monitor is attenuated from +1000V to +100V, it will be attenuated to +100V within 15 seconds.

(Conventional Example 2)

The mini-cleaning device of the second embodiment is prepared, and as shown in Fig. 6(B), the rectifying plate is removed, and the ion generator 24 is attached to the central portion of the FFU 22 (that is, the mini-cleaning device 200 shown in Fig. 1 is prepared. ). Measuring the time that the charging pad monitor decays from +1000V to +100V shows that it decays to about +900V after 60 seconds.

(Comparative Example 1)

Preparation Example 2 mini-clean apparatus of the present invention, another example shown in FIG. 6 (C) of FIG, remove the rectifying plate, the ion generator 24 is mounted in an opening directly above the portion A _3. Measuring the time that the charging pad monitor decays from +1000V to +100V shows that it decays to about +400V after 60 seconds.

From the above results, it was confirmed that in the second embodiment in which the rectifying plate 26 is placed at a predetermined position in the transfer chamber 20, the inside of the semiconductor wafer storage container 10 can be reliably and quickly removed. As is apparent from the first and second embodiments, the first and second embodiments of the inventions are different from the conventional examples 1 and 2, except that the direction of the airflow F is reversed, and the air volume is also large. Therefore, the static elimination is performed reliably and quickly.

According to the present invention, it is possible to provide a mini clean device capable of The interior of the semiconductor wafer storage container is more reliably and quickly removed.

Claims (3)

A mini-cleaning device includes a semiconductor wafer storage container, and a semiconductor wafer is sealed and stored by an opening and closing cover, and an opening and closing portion for loading and unloading the semiconductor wafer is provided; and the transfer chamber is internally cleaned And a transport mechanism disposed in the transfer chamber to take the semiconductor wafer from the semiconductor wafer storage container and transport it to the transfer chamber, wherein a part of the sidewall of the transfer chamber is loaded In the stacker, the loading cassette includes a mounting table on which the semiconductor wafer storage container is placed, and a closing mechanism that can close an opening that communicates with the opening and closing portion, and the blocking mechanism is located in the side wall of the transfer chamber In the transfer chamber, a fan filter unit is disposed to generate a gas flow from above and below the transfer chamber; and an ion generator generates ions for removing the interior of the transfer chamber and the semiconductor wafer storage container; And a rectifying plate located above the opening, spaced apart from the opening, and disposed obliquely toward the opening, the ion generator being mounted on the rectifying plate, the whole The length of the tie plate is configured so that a gas stream containing the upper side of the ions from the storage container to the bottom surface of the semiconductor wafer side of the inflow. The mini-cleaning device according to claim 1, wherein the ion generator is attached to the opening side end of the rectifying plate. The mini-cleaning device of claim 1 or 2, wherein the semiconductor wafer is a tantalum wafer.