Device and method for measuring environmental static electricity and environmental static electricity monitoring system

Abstract

The present disclosure relates to a device and method for measuring environmental static electricity and an environmental static electricity monitoring system. The device for measuring environmental static electricity includes an electrometer, a conductive plate and a switch. The electrometer includes a sensor. The conductive plate is arranged at a certain distance from the electrometer and is aligned with the sensor of the electrometer. The switch is electrically connected to the conductive plate.

Description

Technical Field

[0001] The present disclosure relates to a device and method for measuring environmental static electricity and an environmental static electricity monitoring system, and is particularly used to solve the problem of electrostatic discharge in semiconductor processes. Background Art

[0002] Electrostatic discharge (ESD) is the main factor causing most electronic components or electronic systems to fail and be damaged. Electrostatic discharge is mostly caused by human factors, but it is difficult to avoid. For example, during the manufacturing, production, assembly, testing, storage and transportation of electronic components or systems, static electricity will accumulate in the human body, instruments and storage equipment, and even in the electronic components themselves. People unknowingly bring these objects into contact with each other, thus forming a discharge path, causing the electronic components or systems to be damaged by electrostatic discharge. This damage can cause permanent damage to semiconductor components and computer systems, thus affecting the functions of electronic components or systems and causing electronic products to malfunction.

[0003] Common types of electrostatic discharge (ESD) in semiconductor factories include the human body model (HBM), machine model (MM), and charged device model (CDM). That is, the environment (the drier and cleaner air delivery in the clean room), machines, and workers can all generate ESD due to frictional electrification.

[0004] The gate oxide layer in the chip circuit manufactured by advanced process technology is thinner (such as GAA), so the electric field strength under the same voltage condition is stronger, making the gate oxide layer more vulnerable to damage. This is why the electrostatic protection capability will decline as the component size decreases, and the density of the component packaging (bonding) increases, which makes the threat of electrostatic discharge (ESD) more and more serious. Summary of the invention

[0005] In some embodiments, the present disclosure provides a device for measuring environmental static electricity, comprising an electrometer, a conductive plate, and a switch. The electrometer comprises a sensor, the conductive plate is disposed at a certain distance from the electrometer and is substantially aligned with the sensor of the electrometer, and the switch is electrically connected to the conductive plate.

[0006] In some embodiments, the present disclosure provides an environmental static monitoring system, which includes at least one device for measuring environmental static, a processing device and at least one static eliminator. The device for measuring environmental static includes an electrometer, a conductive plate and a switch. The electrometer includes a sensor, the conductive plate is arranged at a certain distance from the electrometer and is roughly aligned with the sensor of the electrometer, and the switch is electrically connected to the conductive plate. The processing device is connected to the electrometer and the switch of the device for measuring environmental static, and the static eliminator is connected to the processing device.

[0007] In some embodiments, the present disclosure provides a method for measuring environmental static electricity, which includes: providing a conductive plate that can be used to collect environmental static electricity, wherein the conductive plate is connected to a switch; operating the switch to connect the conductive plate to a ground wire; providing an electrometer at a fixed distance from the conductive plate, and using the electrometer to measure the conductive plate that has been switched to be connected to the ground wire so that the electrometer returns to zero; operating the switch to put the conductive plate in an open circuit state; and using the electrometer to measure the static electricity value on the conductive plate.

[0008] The above has been a fairly broad overview of the technical features of the present disclosure so that the detailed description of the present disclosure below can be better understood. Other technical features that constitute the subject matter of the claims of the present disclosure will be described below. It should be understood by those of ordinary skill in the art to which the present disclosure belongs that the concepts and specific embodiments disclosed below can be used quite easily as modifications or designs for other structures or processes to achieve the same purpose as the present disclosure. It should also be understood by those of ordinary skill in the art to which the present disclosure belongs that such equivalent constructions cannot depart from the spirit and scope of the present disclosure as defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Aspects of the present disclosure will be more clearly understood from the following detailed description, taken in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industry practice, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily enlarged or reduced for clarity of illustration.

[0010] Figure 1 FIG. 4 is a schematic diagram of a device for measuring environmental static electricity according to an embodiment of the present disclosure.

[0011] Figure 2 FIG. 4 is an operation flow chart of a device for measuring environmental static electricity according to an embodiment of the present disclosure.

[0012] Figure 3A and 3B FIG. 1 is a schematic diagram of the operation of an electrometer according to an embodiment of the present disclosure.

[0013] Figure 4A and4B FIG. 4 is a schematic diagram of the operation of the device for measuring environmental static electricity according to an embodiment of the present disclosure.

[0014] Figure 5A and 5B FIG. 4 is a schematic diagram of calibration of a device for measuring environmental static electricity according to an embodiment of the present disclosure.

[0015] Figure 6 FIG. 1 is a schematic diagram of an environmental static electricity monitoring system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0016] The following disclosure provides many different embodiments or examples for implementing the different features of the provided subject matter. The specific examples of the elements and arrangements will be described below to simplify this disclosure. Of course, these are only examples and are not intended to be limiting. For example, in the following description, "making the first component be formed above or on the second component" may include an embodiment in which the first component and the second component form direct contact, and may also include an embodiment in which an additional device may be formed between the first component and the second component so that the first component and the second component may not directly contact. In addition, this disclosure may repeat element symbols and / or letters in various examples. This repetition is intended to simplify and clarify and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0017] Additionally, for ease of description, spatially relative terms (e.g., "below," "beneath," "below," "above," "upper," etc.) may be used herein to describe the relationship of one element or device to another element or devices, as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.

[0018] As used herein, terms such as "first", "second", and "third" describe various elements, components, regions, layers, and / or sections, which should not be limited by these terms. These terms may be used only to distinguish elements, components, regions, layers, or sections from one another. Unless the context clearly indicates otherwise, terms such as "first", "second", and "third" used herein do not imply a sequence or order.

[0019] As used herein, the terms "substantially," "generally," "approximately," and "about" are used to describe and explain small variations. When used in conjunction with an event or condition, the terms may relate to instances in which the event or condition occurs precisely as well as instances in which the event or condition occurs very approximately. For example, when used in conjunction with a numerical value, the terms may relate to a range of variation of less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two values ​​is less than or equal to ±10% of the average of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the values ​​may be considered to be "substantially" the same or equal. For example, "substantially" parallel may involve an angular variation range of less than or equal to ±10° relative to 0°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°. For example, "substantially" vertical may involve an angular variation range of less than or equal to ±10° relative to 90°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°.

[0020] With the development of advanced integrated circuit (IC) technology, in order to increase circuit performance, the circuit channel becomes shorter or the gate oxide layer becomes thinner, so that the tolerance of electronic components to electrostatic discharge (ESD) is getting lower and lower, and the manufacturing environment requirements for electrostatic sensitive components are becoming more and more rigorous. In the process of manufacturing, assembly, testing and transportation of electronic products, electrostatic discharge may occur due to an imperfect grounding system, improper operation of personnel or lack of appropriate electrostatic protection measures, resulting in circuit damage or reduced reliability of the product. Among the electrostatic protection measures, in addition to the grounding system and material selection, only the ionizer can neutralize the static electricity on the insulating object. However, in spaces such as semiconductor plants or clean rooms, using only the ionizer is not the best way to eliminate static electricity. It still needs to be combined with relevant measures to achieve the best effect of static elimination.

[0021] Usually, many ionizers are installed in semiconductor factories or clean rooms to neutralize or eliminate static electricity generated in the environment, but the static electricity in the environment is not actually measured, and only a charged plate monitor (CPM) is used to calibrate the ionizer. In addition, the electrometer that can be used to measure the environment requires the user to manually ground and discharge to zero, which is not suitable for real-time monitoring and is difficult to integrate with online monitoring systems and ionizers.

[0022] Figure 1 Schematic diagram of a device 1 for measuring environmental static electricity according to an embodiment of the present disclosure. In some embodiments, the device 1 for measuring environmental static electricity includes an electrometer 11, a conductive plate 12, and a switch 13. The electrometer 11 has a ground wire 113, a signal output 111, and a sensor 115. The electrometer 11 can use the sensor 115 to align with the object to be measured to sense and obtain the static electricity value on the measured object. Further, the electrometer 11 can use the signal output 111 to transmit the measured static electricity value to another device or machine; in addition, the electrometer 11 can use its ground wire 113 to ground the electrometer 11 to zero, so that the electrometer 11 is zeroed.

[0023] like Figure 1 As shown, the conductive plate 12 is used to collect environmental static electricity, and is set at a certain distance from the electrometer 11. In some embodiments, the conductive plate 11 is roughly aligned with the sensor 115 of the electrometer 11 and is set at a certain distance D from the sensor 115. The distance D can be set to 1 cm or 1 inch, but is not limited thereto. In some embodiments, the conductive plate 12 further has a fixing plate 121, one end of the fixing plate 122 is connected to the conductive plate 12, and the other end of the fixing plate 122 is connected to the electrometer 11; the fixing plate 122 can fix the arrangement between the conductive plate 12 and the electrometer 11, and the distance between the conductive plate 12 and the electrometer 11 is fixed.

[0024] Refer to Figure 1 , the switch 13 and the conductive plate 12 are conductively connected to each other. In some embodiments, the switch 13 can be electrically connected to the conductive plate 12 via the conductive wire 15. The switch 13 can be further connected to the ground wire 131 and the specific bias 133, wherein the specific bias 133 can provide a specific bias value, such as 137 volts; in some embodiments, the switch 13 is a three-way switch, and the switch 13 can be switched to form a path connection between the conductive plate 12 and the ground wire 131, or can be switched to form a path connection between the conductive plate 12 and the specific bias 133, or can be switched to form a disconnection between the conductive plate 12 and the ground wire 131 and the specific bias 133.

[0025] Figure 2The operation flow chart of the device for measuring environmental static electricity according to the embodiment of the present disclosure is disclosed. Steps 101 to 103 are related to the operation of using the device 1 to measure environmental static electricity, and steps 201 to 202 are related to the operation of calibrating the device 1.

[0026] refer to Figure 2 When using device 1 to measure environmental static electricity, as shown in step 101, the electrometer 11 of device 1 can be reset to zero first; after the electrometer 11 is reset to zero, as shown in step 102, the device 1 is reset to zero again; when the device 1 is reset to zero, as shown in step 103, the conductive plate 12 will collect environmental static electricity, and the electrometer 11 of device 1 can be used to measure the static electricity value on the conductive plate 12, and the measured static electricity value is the static electricity value of the environment.

[0027] Refer to Figure 2 After the device 1 has been used for a period of time, the device 1 may be calibrated so that the device 1 does not misjudge the environmental static value due to measurement deviation. When calibrating the device 1, as shown in step 201, the device 1 is first reset to zero; after the device 1 is reset to zero, as shown in step 202, the device 1 is used to measure a known specific bias voltage, and it is confirmed that the static value measured by the device 1 is the same as the known specific bias voltage.

[0028] Regarding the above Figure 2 For detailed instructions on the relevant operation process, please refer to the following content.

[0029] Figure 3A and 3B FIG. 1 is a schematic diagram of the operation of the electrometer 11 of the present disclosure embodiment. As described above, the electrometer 11 can use the ground wire 113 to perform zero calibration. In addition to using the ground wire 113 to perform zero calibration, the electrometer 11 can further use Figure 3A Further zeroing correction is performed in the manner shown. Figure 3A First, a grounded object 21 is provided, and the sensor 115 of the electrometer 11 senses the grounded object 21. If the electrometer 11 shows that the measured value is zero, it means that the electrometer 11 has completed the zero calibration. Figure 3B The electrometer 11 of the disclosed embodiment is used to measure the object 22 to be measured; Figure 3B As shown, the user aims the sensor 115 of the electrometer 11 at the object to be measured 22 and keeps a certain distance from the object to be measured 22 to measure the static electricity value on the object to be measured 22; after the sensor 115 senses the object to be measured 22, the value displayed on the electrometer 11 is the static electricity value on the object to be measured 22.

[0030] Figure 4A and 4B FIG. 1 is a schematic diagram of the operation of the device 1 for measuring environmental static electricity according to an embodiment of the present disclosure. Figure 4AThe operation of zeroing calibration before using the device 1 for measuring environmental static electricity disclosed in the present invention is disclosed; Figure 4A As shown, when performing zero calibration, the switch 13 is switched to form an electrical path between the conductive plate 12 and the grounding wire 131, so that the conductive plate 12 is in a grounded state without any static electricity. At this time, the sensor 115 of the electrometer 11 senses the conductive plate 12, and the static electricity value of the conductive plate 12 that can be measured by the electrometer 11 is zero.

[0031] Figure 4B The operation of using the device 1 for measuring environmental static electricity disclosed in the present invention to perform environmental static electricity measurement is disclosed; Figure 4B As shown, the switch 13 is switched to open the conductive plate 12, the ground line 131 and the specific bias voltage 133, so that the conductive plate 12 can collect environmental static electricity. At this time, the sensor 115 of the electrometer 11 senses the conductive plate 12, and the static value of the conductive plate 12 measured by the electrometer 11 is the static value of the environment. With this operation, the user can use the device 1 for measuring environmental static electricity to measure and obtain the static value of the environment; further, the signal output 111 of the electrometer 11 can be used to transmit the measured environmental static value to an external device or machine.

[0032] After the device 1 for measuring environmental static electricity is used for a period of time, some measurement errors may occur. Figure 4A and 4B As shown, the electrometer 11 of the device 1 can be zeroed and calibrated before measurement. However, in order to make the device 1 for measuring environmental static electricity more accurately measure the environmental static electricity value, it is necessary to further calibrate the device 1. Figure 5A Before further calibration, the electrometer 11 must also be zeroed; Figure 5A As shown, the switch 13 is switched to form an electrical path between the conductive plate 12 and the grounding line 131, so that the conductive plate 12 is in a grounded state without any static electricity. At this time, the sensor 115 of the electrometer 11 senses the conductive plate 12, and the static electricity value of the conductive plate 12 measured by the electrometer 11 is zero. Figure 5B As shown, the switch 13 is switched to form an electrical path between the conductive plate 12 and the specific bias 133 that can provide a specific voltage, so that the conductive plate 12 has a voltage value provided by the specific bias 133, such as 137 volts. At this time, the sensor 115 of the electrometer 11 senses the conductive plate 12, and the static value measured by the electrometer 11 should be the same as the voltage value provided by the specific bias 133. If the static value measured by the electrometer 11 is different from the voltage value provided by the specific bias 133, it means that the device 1 for measuring environmental static electricity must be adjusted so that it can correctly measure the static value before continuing to measure environmental static electricity.

[0033] Figure 6 Schematic diagram of an environmental static monitoring system according to an embodiment of the present disclosure. Figure 6 As shown, an environmental static monitoring system 100 of the present disclosure is applied to a clean room 7. The environmental static monitoring system 100 includes a plurality of devices 1 for measuring environmental static electricity, a processor 3, and a plurality of static eliminators 5. In some embodiments, the plurality of devices 1 for measuring environmental static electricity and the plurality of static eliminators 5 are disposed in the clean room 7. In some embodiments, referring to Figure 6 , the plurality of conductive plates 12 of the plurality of devices 1 for measuring environmental static electricity are configured to be connected to a single switch 13. In some embodiments, the processing device 3 has a processor 31 and a controller 32, and the plurality of signal outputs 111 of the plurality of electrometers 11 of the plurality of devices 1 for measuring environmental static electricity are configured to be connected to the processor 31 of the processing device 3, so that the electrometers 11 can transmit the numerical information obtained by their measurements to the processor 31 of the processing device 3, and the plurality of static eliminators 5 and switches 13 are configured to be connected to the controller 32 of the processing device, so that the user can manually operate and control the plurality of static eliminators 5 and switches 13 through the controller 32 of the processing device 3, or the controller 32 can automatically operate and control the plurality of static eliminators 5 and switches 13 according to the instructions of the processor 31. In some embodiments, the processing device 3 is further connected to a display 35, and the user can understand the environmental static distribution status in the clean room 7 in real time through the display 35.

[0034] like Figure 6As shown, the clean room 7 is roughly divided into four areas, namely A, B, C and D, and each area is arranged with at least one static eliminator 5 and one device 1 for measuring environmental static electricity. Taking area A as an example, it is arranged with one static eliminator 5 and three devices 1 for measuring environmental static electricity, wherein the range in which the static eliminator 5 can effectively eliminate static electricity is roughly the range of area A, and the three devices 1 for measuring environmental static electricity that match the static eliminator 5 are arranged in area A. In other words, the distance between the device 1 for measuring environmental static electricity and the static eliminator 5 is less than or equal to the range in which the static eliminator 5 can effectively eliminate static electricity, so that the environmental static electricity in area A can be effectively measured. Taking area A as an example, three devices 1 for measuring environmental static electricity are arranged in area A, so the devices 1 can be used to measure the environmental static electricity value in area A in the clean room 7, and the device 1 can transmit the measured environmental static electricity value in area A to the processor 31 of the processing device 3 through the signal output 111 of the electrometer 11. After receiving the information of the environmental static electricity value, the processor 31 can present the information on the display 35, and the user can understand the environmental static electricity value in area A through the display 35; further, if the user observes from the display 35 that the environmental static electricity value in area A is too high, the user can start the static eliminator 5 set in area A through the controller 32 of the processing device 30 to eliminate the environmental static electricity in area A. Similarly, the user can observe from the display 35 whether the environmental static electricity in area A has been eliminated by the static eliminator 5. In addition to manually controlling the static eliminator 5, the processing device 3 can be set to automatically start the static eliminator 5 through the environmental static value measured by the device 1 for measuring environmental static electricity; taking area A as an example, the three devices 1 for measuring environmental static electricity set in area A can transmit the measured environmental static value in area A to the processor 31 of the processing device 3. If the environmental static value in area A transmitted back by the device 1 received by the processor 31 is higher than a certain specific value, the processor 31 can automatically transmit a start command to the controller 32, and the controller 32 can start the static eliminator 5 in area A according to the start command to eliminate the environmental static electricity in area A.

[0035] Likewise, Figure 6 The device 1 for measuring environmental static electricity and the static eliminator 5 in the B, C, and D areas shown can be operated in the same or similar manner as the device 1 for measuring environmental static electricity and the static eliminator 5 in the area A described above; in particular, the user can simultaneously observe the measured environmental static electricity values ​​in the four areas A, B, C, and D through the display 35, and the processing device 3 can simultaneously or separately start the static eliminator 5 in the four areas A, B, C, and D. In addition, the clean room is divided into multiple areas, such as Figure 6The four areas A, B, C, and D shown not only take into account the range within which each static eliminator 5 of the environmental static electricity monitoring system 100 can effectively eliminate environmental static electricity, but also enable the environmental static electricity monitoring system 100 to more accurately measure the environmental static electricity values ​​in various locations in the clean room 7, and to accurately and effectively eliminate static electricity for different environmental static electricity values ​​in different areas.

[0036] In addition, if Figure 6 As shown, multiple devices 1 of the environmental static monitoring system 100 share a single switch 13; thus, after the environmental static monitoring system 100 has been used for a period of time, the switch 13 can be started manually by the user or automatically by the processing device 3 to reset and calibrate the multiple devices 1 of the environmental static monitoring system 100.

[0037] According to the above, the environmental static electricity monitoring system 100 disclosed in the present invention can effectively monitor the environmental static electricity value in a semiconductor factory, such as a clean room, and can effectively and accurately eliminate the environmental static electricity in each small area in the factory, without causing the static electricity in some areas to be not completely eliminated, or excessive use of the static eliminator 5 to generate excess charge in the said area.

[0038] The features of several embodiments have been summarized above so that those skilled in the art can better understand the aspects of the present disclosure. Those skilled in the art will appreciate that they can easily use the present disclosure as a basis for designing or modifying other programs and structures to implement the same purposes and / or achieve the same advantages as the embodiments described herein. Those skilled in the art will also appreciate that these equivalent constructions should not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and modifications to the present disclosure.

[0039] Explanation of symbols

[0040] 1 Device for measuring environmental static electricity

[0041] 11. Electrometer

[0042] 111 Signal output

[0043] 113 Ground wire

[0044] 115 Sensor

[0045] 12 Conductive plate

[0046] 121 Fixed plate

[0047] 13 Switcher

[0048] 131 Wire

[0049] 133 Fixed bias

[0050] 15 Conductive thread

[0051] 101 Steps

[0052] 102 Steps

[0053] 103 Steps

[0054] 21 Grounded Objects

[0055] 22 Objects to be tested

[0056] 201 Steps

[0057] 202 Steps

[0058] 3 Processing device

[0059] 31 Processor

[0060] 32 Controller

[0061] 35 Display

[0062] 5. Static Eliminator

[0063] 7 Clean Room

[0064] 100 Environmental static monitoring system

Claims

1. A device for measuring environmental static electricity in a clean room, comprising: an electrometer having a sensor and a first ground wire; a conductive plate configured to collect the ambient static electricity in the clean room and disposed at a fixed distance from the electrometer and aligned with the sensor of the electrometer; as well as a switch electrically connected to the conductive plate and a second grounding wire; The conductive plate and the electrometer are fixedly arranged with respect to each other, wherein the switch is a three-way switch arranged to switch the conductive plate to be electrically connected to the second ground line, or to switch the conductive plate to be connected to a specific voltage, or to switch the conductive plate to form an open circuit with the second ground line and the specific voltage. 2 . The device for measuring environmental static electricity in a clean room according to claim 1 , further comprising a fixing plate, wherein the fixing plate is connected to the conductive plate and the electrometer.

3. An environmental static monitoring system for a clean room, comprising: a single static eliminator configured to eliminate static electricity within an area within the clean room; A plurality of devices for measuring environmental static electricity, each of the plurality of devices for measuring environmental static electricity comprising: an electrometer having a sensor; and a conductive plate disposed a fixed distance from the electrometer and substantially aligned with the sensor of the electrometer, the conductive plate and the electrometer being fixedly disposed relative to each other; a switch electrically connected to the conductive plates of the plurality of devices for measuring environmental static electricity; and a processing device connected to the electrometers of the plurality of devices for measuring environmental static electricity, the switcher, and the single static eliminator; The plurality of devices for measuring environmental static electricity are matched with the single static eliminator and are arranged in the area, wherein the switch may be a three-way switch, which is arranged to switch the conductive plate to be electrically connected to the ground wire, or to switch the conductive plate to be connected to a specific voltage, or to switch the conductive plate to form an open circuit with the ground wire and the specific voltage.

4. The environmental static monitoring system for a clean room according to claim 3, wherein the processing device is configured to receive signals transmitted by the electrometers of the plurality of devices for measuring environmental static electricity, and is configured to control the single static eliminator.

5. A method for eliminating environmental static electricity in an area within a clean room, comprising: Providing a plurality of conductive plates capable of collecting environmental static electricity in the area, wherein the plurality of conductive plates are connected to the switch; Operating the switch to connect the plurality of conductive plates to a ground line; Providing a plurality of electrometers, the plurality of electrometers are respectively arranged at a fixed distance from the plurality of conductive plates, and the conductive plates and the electrometers are fixedly arranged with respect to each other, and using the plurality of electrometers to respectively measure the plurality of conductive plates switched to be connected to the ground line, so that the plurality of electrometers are zeroed; Operating the switch to put the plurality of conductive plates into an open circuit state; as well as Using the plurality of electrometers to measure the static electricity values ​​on the plurality of conductive plates respectively; providing a single static eliminator configured to eliminate ambient static electricity within the area within the clean room, wherein the single static eliminator is disposed within the area along with the plurality of conductive plates and the plurality of electrometers; The single static eliminator is used to eliminate environmental static electricity in the area based on the static electricity value, wherein the switch is a three-way switch, which is arranged to switch the plurality of conductive plates to be electrically connected to the ground line, or to switch the plurality of conductive plates to be connected to a specific voltage, or to switch the plurality of conductive plates to form a circuit with the ground line and the specific voltage.

6. The method according to claim 5, further comprising: operating the switch to connect the plurality of conductive plates to the specific voltage; and The plurality of electrometers are used to measure the plurality of conductive plates, and it is confirmed whether the static electricity values ​​on the plurality of conductive plates measured by the plurality of electrometers are the same as the voltage value of the specific voltage.

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