JP2008141049A - Cleaning apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent damage of device elements contained in an object to be cleaned. <P>SOLUTION: A cleaning apparatus includes a gas tank 22, gas valve 26, chemical tank 20, mixing nozzle 18, electrode 10 and the like, and computing section 14 and the like. The gas tank 22 feeds a gas. The gas valve 26 adjusts the feeding amount of the gas per unit time. The chemical tank 20 feeds a chemical. The mixing nozzle 18 mixes the gas fed from the gas tank 22 and the chemical fed from the chemical tank 20, and sprays the cleaning solution. The electrode 10 and the like detect the current value that corresponds to the electric charge amount of the cleaning solution. The computing section 14 and the like control the adjusting means so as to reduce the feeding amount of the gas per unit time when the absolute value of the current is equal to or greater than a threshold. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cleaning apparatus and a cleaning method, and more particularly to a cleaning apparatus and a cleaning method by a method including use of a gas flow.

  Charging of a substrate including a TFT (Thin Film Transistor) element or the like may cause a breakdown failure of the element. For this reason, charging of an object to be cleaned when cleaning such a substrate is an important problem.

  In the era when the object to be cleaned was cleaned only with liquid, at least such a problem did not occur due to charging of the cleaning liquid. However, when high pressure jet cleaning is performed by mixing a liquid and a gas, such a problem has arisen due to charging of the cleaning liquid.

  Conventional countermeasures against such problems include a method of confirming the charge amount in a dry environment after cleaning, and a method of using a device for neutralizing charges in advance.

  Patent Document 1 discloses a two-fluid ejection nozzle that removes contaminants adhering to the surface of an object to be cleaned as one of such countermeasures. The two-fluid ejection nozzle includes a gas supply channel, an electrode unit, a cleaning liquid supply channel, and a cooling unit. The gas supply channel has a supply port for supplying gas and a jet port for ejecting the gas. The electrode unit is provided between the supply port and the jet port of the gas supply channel, and applies either a DC voltage or an AC voltage to turn the gas into plasma. The cleaning liquid supply channel supplies the cleaning liquid to either the supply port or the jet port of the gas supply channel. The cooling unit cools the electrode unit. The two-fluid ejection nozzle expands the volume by converting the gas into plasma by the electrode unit, and ejects the cleaning liquid supplied by the cleaning liquid supply channel as a plasma / cleaning liquid two-fluid jet from the outlet of the gas supply channel.

  According to the invention disclosed in Patent Document 1, the amount of gas used can be reduced, and contaminants attached to the surface of the semiconductor wafer substrate can be removed without being charged.

  Patent Document 2 discloses a cleaning apparatus including a nozzle with an oscillator that supplies a cleaning liquid to which a high frequency is applied toward a substrate surface. The cleaning device arranges a sensor made of a piezoelectric element at the same height as the substrate and at a standby position separated from the substrate. The sensor measures the high-frequency energy of the cleaning liquid by discharging the cleaning liquid from the nozzle onto the upper surface of the sensor. The cleaning device adjusts the voltage or current applied to the oscillator provided in the nozzle based on the high-frequency energy value.

  According to the invention disclosed in Patent Document 2, a constant high frequency energy can always be applied to the cleaning liquid.

  Patent Document 3 discloses a semiconductor wafer cleaning method that performs a cleaning test using a test piece, detects charge-up damage of a semiconductor wafer, and sets cleaning conditions that do not cause charge-up damage.

  According to the invention disclosed in Patent Document 3, a semiconductor wafer can be cleaned with high yield and high reliability.

  Patent Document 4 discloses a spray tip that is disposed in a cleaning device and injects cleaning water. The spray tip has a first nozzle tip that is formed of a material that generates negative static electricity when the cleaning water is sprayed and a spray port that sprays the cleaning water when the cleaning water passes. And at least a second nozzle tip formed of a material that generates positive static electricity. The cleaning water is jetted through the first nozzle tip and the second nozzle tip.

  According to the invention disclosed in Patent Document 4, it is possible to prevent the generation of static electricity and prevent the object to be cleaned from being charged with static electricity. In Patent Document 4, frictional charging caused by friction between the liquid and gas constituting the cleaning liquid is a cause of the cleaning liquid charging. In addition to this, peeling charge generated by peeling of the liquid from the inner wall of the nozzle at the nozzle outlet can be considered as the cause of charging.

  Patent Document 5 discloses a semiconductor wafer cleaning apparatus that ejects droplets toward the surface of a semiconductor wafer that is an object to be cleaned and removes contaminants attached to the surface. The semiconductor wafer cleaning apparatus injects rinse pure water in which carbon dioxide gas is dissolved toward the back surface of the semiconductor wafer, and grounds the current flowing from the charged droplets to the semiconductor wafer to the outside through the rinse pure water.

According to the invention disclosed in Patent Document 5, static electricity generated when jetting cleaning droplets can be effectively removed, so that a semiconductor wafer as an object to be cleaned and wirings formed thereon can be used. The cleaning operation can be performed without causing electrical damage.
JP-A-11-345797 JP-A-10-303161 JP-A-6-275591 JP 2003-243333 A JP 2000-277476 A

  However, in the inventions disclosed in Patent Document 1, Patent Document 3, Patent Document 4, and Patent Document 5, although the charge of the object to be cleaned is reduced, the possibility of destruction of the element is not sufficiently lowered. There is a problem that there is. For example, the invention disclosed in Patent Document 1 neutralizes the charge of an object to be cleaned with a plasma gas. However, since the actual charge amount of the object to be cleaned is not known, the charge may not be neutralized. If cleaning is repeated for a long period of time without checking the cleaning conditions, the conditions that can suppress the charge level to an appropriate level may change due to disturbances or other causes, so it will be impossible to neutralize the electric charge before long. The possibility of being increased gradually. The same applies to the inventions disclosed in Patent Document 3, Patent Document 4, and Patent Document 5. This is the cause of the problem described above.

  In the invention disclosed in Patent Document 2, there is a problem that the charging of the object to be cleaned is not considered at all.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cleaning apparatus and a cleaning method capable of effectively preventing destruction of elements included in the object to be cleaned.

  In order to achieve the above object, according to an aspect of the present invention, the cleaning device includes a gas supply means, an adjustment means, a liquid supply means, a nozzle, a detection means, and a control means. The gas supply means supplies gas. The adjusting means adjusts the supply amount of gas per unit time. The liquid supply means supplies a liquid. The nozzle mixes the gas supplied by the gas supply means and the liquid supplied by the liquid supply means, and ejects a mixture of the gas and the liquid. The detection means detects a corresponding amount corresponding to the charge amount of the mixture. When the absolute value of the corresponding amount is equal to or greater than the threshold, the control unit controls the adjustment unit so as to decrease the supply amount of gas per unit time.

  Moreover, it is desirable that the above-described detection means includes an electrode within the diffusion range of the mixture ejected from the nozzle and a measurement means. The measuring means measures a value corresponding to the amount of electrons transferred between the mixture and the electrode. In addition, it is desirable that the control means includes means for feedback controlling the adjustment means.

Or it is desirable that the above-mentioned measuring means includes an ammeter.
Or it is desirable that the above-mentioned measuring means includes a coulomb meter.

  The control means described above preferably includes a recording means, an average calculating means, and a means for controlling the adjusting means. The recording means records the corresponding amount. The average calculation means calculates the average value of the correspondence amounts based on the correspondence amounts recorded by the recording means. The means for controlling the adjusting means controls the supply amount so that the content of the control differs according to the magnitude relationship of the average value calculated by the average calculating means with respect to the threshold value.

  The control means described above preferably includes a recording means, a charge width calculation means, and a means for controlling the supply amount. The recording means records the corresponding amount. The charging width calculation unit calculates a difference between the maximum value and the minimum value in the corresponding amount after the supply amount is last controlled among the corresponding amounts recorded by the recording unit. The means for controlling the supply amount controls the adjustment means so as to decrease the supply amount of gas per unit time when the absolute value of the average value is equal to or greater than the threshold value.

  According to another aspect of the present invention, the cleaning method includes an ejection step, a detection step, and a control step. The ejection step ejects a mixture of gas and liquid. The detection step detects a corresponding amount corresponding to the charge amount of the mixture ejected in the ejection step. The control step controls the supply amount so that the supply amount of the gas per unit time decreases when the absolute value of the corresponding amount is equal to or greater than the threshold value.

  The cleaning apparatus and the cleaning method according to the present invention can effectively prevent destruction of elements included in the object to be cleaned.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

FIG. 1 is a diagram illustrating a configuration of a cleaning apparatus according to the present embodiment. Referring to FIG. 1, the cleaning apparatus according to the present embodiment includes an electrode 10, an ammeter 12, a calculation unit 14, a signal generation unit 16, a mixing nozzle 18, a chemical tank 20, and a CO ₂ bubbler. 21, a gas tank 22, a liquid pump 24, a gas pump 26, a chemical valve 28, a gas valve 30, a carbon dioxide tank 32, and a carbon dioxide valve 34.

The electrode 10 is a metal rod that is within the diffusion range of the cleaning liquid ejected from the mixing nozzle 18 and exchanges electrons between the chemical liquid and gas mixture discharged by the mixing nozzle 18. In the present embodiment, the position of the electrode 10 may be disposed above (a position close to the mixing nozzle 18) or below (a position far from the mixing nozzle 18) with respect to the object 50 to be cleaned. FIG. 1 shows a state in which the electrode 10 is disposed above the object to be cleaned 50. In the case of being arranged below, the measurement using the electrode 10 is performed before the object to be cleaned 50 is conveyed. In this case, the cleaning object 50 is cleaned after the cleaning conditions are adjusted according to the measurement result. In the present embodiment, this mixture is referred to as “cleaning liquid”. The ammeter 12 measures the current flowing through the electrode 10. The current value measured by the ammeter 12 corresponds to the charge amount of the cleaning liquid. This is because the current flowing through the electrode 10 is generated by unneutralized electrons and ions contained in the cleaning liquid. As a result, the electrode 10 and the ammeter 12 detect a value corresponding to the charge amount of the cleaning liquid. In the present embodiment, the amount of charge due to unneutralized electrons and ions contained in the cleaning liquid is referred to as “charge amount”. The calculation unit 14 selects the type of control signal generated by the signal generation unit 16 based on the current value measured by the ammeter 12. The signal generator 16 generates control signals for opening and closing the chemical liquid valve 28, the gas valve 30, and the carbon dioxide valve 34. The signal generator 16 is also a device that generates a control signal for changing the discharge amount per unit time of the liquid pump 24 and the gas pump 26. Thereby, the cleaning conditions for the object to be cleaned 50 change. Further, the signal generation unit 16 moves the object to be cleaned 50 by a table (not shown) (the object to be cleaned 50 may be moved by a roller instead of the table, or the cleaning is performed while rotating the object to be cleaned 50). Although the object to be cleaned 50 may be moved according to the method, in this embodiment, the object to be cleaned 50 is moved by a table. As described above, the mixing nozzle 18 mixes the chemical liquid with the gas to obtain a cleaning liquid. The mixing nozzle 18 injects the cleaning liquid onto the object to be cleaned 50. The chemical liquid tank 20 stores the chemical liquid. In the case of the present embodiment, water is used as the chemical solution. This water is sprayed as a cleaning liquid by the mixing nozzle 18 and then supplied again to the chemical liquid tank 20 through a drainage channel and a purification device (not shown) (in the case where the cleanliness of the cleaning object 50 is strongly required). The sprayed cleaning liquid may be disposable). The CO ₂ bubbler 21 is for efficiently mixing carbon dioxide into a chemical solution. When it directly supplying carbon dioxide to the liquid medicine of the pipe, only leaving a large bubble as in the case of dry ice was introduced into the water, because the carbon dioxide immiscible almost a chemical, carbon dioxide in the chemical fluid in CO ₂ bubbler 21 The fine bubbles are ejected and the chemical solution and carbon dioxide are mixed. Incidentally, in the case of the present embodiment, the CO ₂ bubbler 21 is obtained by inserting a carbon dioxide pipe into a water tank containing a chemical solution.

The gas tank 22 stores gas. In the case of the present embodiment, this gas is nitrogen gas. The liquid pump 24 applies pressure to the chemical liquid in which carbon dioxide is mixed in the CO ₂ bubbler 21. The gas pump 26 applies pressure to the gas flowing out from the discharge port of the gas tank 22. The chemical liquid valve 28 adjusts the flow rate of the chemical liquid per unit time by opening and closing the passage through which the chemical liquid passes. The gas valve 30 adjusts the flow rate of the gas per unit time by opening and closing the passage through which the gas passes. The carbon dioxide tank 32 stores the compressed carbon dioxide. The carbon dioxide valve 34 adjusts the flow rate of carbon dioxide per unit time by opening and closing a passage through which carbon dioxide passes.

  Incidentally, carbon dioxide is mixed in order to lower the specific resistance value of water. Instead of carbon dioxide, the specific resistance of water may be lowered by mixing a gas that is soluble in water such as ammonia, but in this embodiment, carbon dioxide is used. However, the use of carbon dioxide is only for adjusting the specific resistance of the chemical solution.

  The computing unit 14 includes a recording device 40 and a computer 42. The recording device 40 records the current value measured by the ammeter 12 in time series. The computer 42 calculates the current value measured by the ammeter 12 and recorded by the recording device 40, and determines whether or not the calculated value exceeds a threshold value. The computer 42 determines the opening / closing amount of the chemical liquid valve 28, the gas valve 30, and the carbon dioxide valve 34, the signal specifying the discharge pressure of the liquid pump 24 and the gas pump 26, and other signals according to the result of the determination. It is also a device that outputs a signal to the signal generator 16.

  The computer 42 includes an interface 420, a keyboard 422, a CPU (Central Processing Unit) 424, and a memory 426. The interface 420 receives input of information recorded by the recording device 40. The interface 420 is also a device that outputs a signal to the signal generation unit 16. The keyboard 422 receives input of information by the user. The CPU 424 processes various information. The memory 426 stores information processed by the CPU 424 and other information.

  Referring to FIG. 2, the program executed by computer 42 executes the following control regarding prevention of charging.

  In step S50, CPU 424 outputs a signal to signal generation unit 16 via interface 420. The signal generator 16 outputs control signals to the liquid pump 24, the gas pump 26, the chemical liquid valve 28, and the gas valve 30 in accordance with the signal. The flow rate per unit time of the chemical solution or gas represented by the signal output by the CPU 424 at this time is stored in the memory 426 in advance. These flow rates may be input by an operator via the keyboard 422, or may be calculated in advance by the CPU 424 based on an allowable charge amount corresponding to the object to be cleaned 50. The method for calculating these flow rates is not particularly limited, but in the case of the present embodiment, it is calculated by multiplying the allowable charge amount according to the object to be cleaned 50 by a predetermined coefficient. Thereby, the supply amount per unit time of at least one of the gas stored in the gas tank 22 and the chemical liquid stored in the chemical liquid tank 20 is controlled. When they are controlled, the chemical liquid and the gas are mixed in the mixing nozzle 18 to become a cleaning liquid. The cleaning liquid is ejected from the mixing nozzle 18. Thereby, the cleaning of the cleaning object 50 is started.

  In step S52, CPU 424 outputs a control signal for operating the above-described table to a driving device (not shown) of the table via interface 420 according to the program stored by itself. Thereby, the to-be-cleaned object 50 moves. Meanwhile, electrons flow into the electrode 10 from the cleaning liquid. Alternatively, ions contained in the cleaning liquid take electrons from the electrode 10. Thereby, a current flows through the electrode 10. The ammeter 12 measures the current flowing through the electrode 10. The recording device 40 records the current value measured by the ammeter 12 in time series.

  In step S54, the conductivity sensor 36 measures the conductivity of the chemical solution mixed with carbon dioxide gas. The measured conductivity data is output to the interface 420. The CPU 424 causes the signal generator 16 to open and close the carbon dioxide valve 34 so that the electrical conductivity becomes a value within a predetermined range. If the conductivity is higher than that range, the carbon dioxide valve 34 is closed. If the conductivity is below that range, the carbon dioxide valve 34 is opened.

  In step S58, interface 420 accepts the input of current value data recorded by recording device 40. The CPU 424 calculates the average value of the current values recorded by the recording device 40 based on the data. The average value may be, for example, the average value of all current values after the start of recording, but in the case of the present embodiment, the average value is the last gas supply amount per unit time. It is assumed that the current value recorded by the recording device 40 after the control is an average value.

  In step S <b> 58, CPU 424 determines whether or not the value calculated in step S <b> 58 is within a predetermined range according to object to be cleaned 50. In the case of the present embodiment, CPU 424 determines whether or not the calculated value is within a predetermined range based on whether or not the absolute value of the calculated value is smaller than a threshold value. The threshold value is stored in the memory 426. In the case of this embodiment, a plurality of values used as threshold values are stored in advance in the memory 426. Which value is used as the threshold value is determined based on information input by the operator via the keyboard 422 before the cleaning is started. Thereby, the threshold value becomes a predetermined value before the start of cleaning. If it is determined that the value calculated in step S58 is within the predetermined range (YES in step S58), the process proceeds to step S60. Otherwise (NO in step S58), the process proceeds to step S62.

  In step S60, CPU 424 determines whether or not to end the cleaning. If it is determined that the cleaning is to be ended (YES in step S60), the process ends. If not (NO in step S60), the process proceeds to step S52.

  In step S62, CPU 424 changes the cleaning condition. In order to change the cleaning condition, the CPU 424 outputs a signal for reducing the amount of the chemical liquid that passes through the gas valve 30 during the unit time to the signal generation unit 16. The signal generator 16 outputs a control signal for slightly closing the gas valve 30 according to the signal. In the case of the present embodiment, the amount of the chemical solution that is reduced by the operation of the gas valve 30 is constant regardless of the difference between the average value calculated in step S58 and the threshold value.

The operation of the cleaning apparatus based on the above structure and flowchart will be described.
The CPU 424 causes the signal generator 16 to output a control signal to the liquid pump 24, the gas pump 26, the chemical liquid valve 28, and the gas valve 30 (step S50). Thereby, the cleaning of the cleaning object 50 is started.

  When the control signal is output, the CPU 424 causes the signal generator 16 to output the control signal to the table. In the meantime, electrons flow into the electrode 10 or electrons flow out of the electrode 10. The ammeter 12 measures the current flowing through the electrode 10. The recording device 40 records the current value measured by the ammeter 12 in chronological order (step S52).

  When the current value is recorded, the conductivity sensor 36 measures the conductivity of the chemical solution mixed with carbon dioxide gas. The CPU 424 causes the signal generator 16 to open and close the carbon dioxide valve 34 so that the electrical conductivity becomes a value within a predetermined range (step S54). Thereby, the electrical conductivity of a chemical | medical solution is kept in a fixed range.

  In this embodiment, since water is used as the chemical solution, the conductivity of the chemical solution should be a constant value unless there is a special reason. However, when the chemical solution is repeatedly used, various ions are mixed into the chemical solution. The conductivity changes when ions are mixed. When the electrical conductivity changes, the relationship between the charge amount of the cleaning liquid and the current value measured by the ammeter 12 also changes. If this relationship changes, the charge amount cannot be estimated based on the current value measured by the ammeter 12. For this reason, the electrical conductivity of a chemical | medical solution is kept in the fixed range by mixing carbon dioxide gas.

  When the carbon dioxide valve 34 is opened and closed, the CPU 424 calculates the average value of the current values recorded by the recording device 40 based on the current value data recorded by the recording device 40 (step S58). When the average value is calculated, the CPU 424 determines whether or not the average value of the current values recorded by the recording device 40 is within a predetermined range (step S58). In this case, if the average value of the current values is out of the range (NO in step S58), CPU 424 decreases the amount of the chemical liquid that passes through gas valve 30 during unit time (step S62). Thereby, the cleaning conditions of the cleaning target 50 are changed.

  When the cleaning conditions for the article 50 to be cleaned are changed, the processing from step S52 to step S58 is repeated once. Thereafter, the CPU 424 determines whether or not the average value of the current values recorded by the recording device 40 is within a predetermined range (step S58). In this case, if the average value is within a predetermined range (YES in step S58), CPU 424 determines whether or not to end the cleaning (step S60). In this case, if the cleaning is not terminated (NO in step S60), the processes in steps S52 to S60 are repeated. Meanwhile, if the average value of the current values recorded by recording device 40 is outside the predetermined range (NO in step S58), the processing in steps S52 to S58 is repeated once through the processing in step S62.

Thereafter, when the cleaning is finished (YES in step S60), the process is finished.
As described above, the cleaning apparatus according to the present embodiment measures the charge amount of the cleaning liquid during cleaning and performs feedback control based on the charge amount. This makes it possible to constantly monitor the charging state of the cleaning liquid. Since the charging state is constantly monitored, the element is prevented from being destroyed by static electricity charged on the object to be cleaned between monitoring. As a result, it is possible to provide a cleaning device that can prevent destruction of elements included in the object to be cleaned.

  Further, the cleaning device according to the present embodiment decreases the gas supply amount per unit time when the average value of the current recorded by the recording device 40 is outside the predetermined range. Since the supply amount is controlled based on the average value, it is possible to avoid a situation in which the cleaning conditions are controlled against the operator's expectation due to a suddenly generated factor.

  In addition, the cleaning apparatus according to the present embodiment is moved between the cleaning liquid and the electrode 10 by the electrode 10 within the diffusion range of the cleaning liquid ejected from the mixing nozzle 18 and the ammeter 12 outside the range. The amount of electrons is measured as a current value. Since the amount of charge is not measured by a sensor installed outside the diffusion range of the cleaning liquid, the measured value is significantly more reliable than when the current is measured based on the scattered cleaning liquid. In addition, since the electrode 10 is a metal rod, failure due to breakdown or short-circuiting of the insulation can be greatly suppressed as compared with the case where any sensor is exposed to the cleaning liquid.

  In addition, the cleaning device according to the present embodiment measures the current value with the ammeter 12 and uses it for feedback control. Generally, when measuring the charge amount, a voltage value corresponding to the charge amount is measured. However, when measuring the charge amount in the cleaning liquid, the potential difference caused by charging is a slight value. Accordingly, it is considered difficult to measure the charge amount in the cleaning liquid. On the other hand, the cleaning apparatus according to the present embodiment indirectly measures the charge amount in the cleaning liquid easily by measuring the current value. Since the charge amount in the cleaning liquid can be easily measured, the cleaning device according to the present embodiment can easily realize feedback control based on the charge amount in the cleaning liquid.

  Instead of measuring the current due to the electrons flowing into the electrode 10 from the mixture of the chemical and gas with the ammeter 12, the voltage due to the electrons flowing into the electrode 10 may be measured with the voltmeter at the electrode 10. Good. However, in this case, the voltage value to be measured is a considerably small value, so it is necessary to use a highly accurate voltmeter selected based on the voltage value measured in advance. In addition, some value corresponding to the amount of electrons flowing into the electrode 10 may be measured by a measuring device corresponding to the value. An example of such a measuring device is a coulomb meter 13. The coulomb meter 13 is a device that measures the amount of electric charge that has flowed to the electrode 10. In this case, the amount of charge carried by the electrons is measured as a value corresponding to the amount of electrons flowing into the electrode 10. The recording device 40 records the amount of charge measured by the coulomb meter 13 in time series. It is an item which can be arbitrarily determined how long the amount of charge is measured. FIG. 3 is a diagram showing the configuration of the cleaning device when the coulomb meter 13 is used.

  The shape of the electrode 10 may not be a rod. For example, the electrode 10 may have a flat plate shape. The material of the electrode 10 is not limited to a metal as long as an electric current can flow. For example, it may be made of semiconductor.

  Further, instead of detecting the amount corresponding to the charge amount of the cleaning liquid using the electrode 10 and the ammeter 12, such an amount may be detected using another device. For example, an induced electromotive force generated by applying a magnetic field to the space in which the cleaning liquid is dispersed and passing the cleaning liquid through the magnetic field may be measured.

  Further, instead of mixing carbon dioxide gas so as to keep the conductivity constant in step S54, the threshold value used in step S58 may be calculated based on the conductivity measured by the conductivity sensor 36. The formula for calculation may be specified based on the least square method by plotting the relationship between the measured conductivity and the current value measured by the ammeter 12. In this case, instead of spraying the cleaning liquid onto the electrode 10, electric power having a constant current value is supplied. Of course, this formula may be specified by other methods.

  In step S58, the CPU 424 finally controls the supply amount per unit time of at least one of the mixing nozzle 18, the liquid pump 24, and the gas pump 26 and eventually the gas and the chemical instead of calculating the average value. Then, the difference between the maximum value and the minimum value of the current value recorded by the recording device 40 may be calculated. In this case, the CPU 424 determines whether or not the difference is within a predetermined range. Thereby, since the charge amount is stabilized, it is possible to effectively prevent the element from being destroyed by temporarily increasing the charge amount. As a result, it is possible to provide a cleaning device that can prevent the destruction of the elements included in the object to be cleaned, and in particular, the destruction of the elements caused by temporary fluctuations in the charge amount.

  In step S <b> 62, the CPU 424 may cause the interface 420 to output a signal for closing the chemical valve 28 together with the gas valve 30. In this case, the signal generator 16 outputs a control signal for closing the chemical liquid valve 28 and the gas valve 30 in accordance with those signals. As a result, the cleaning condition of the object to be cleaned 50, that is, the supply amount of gas and chemical solution per unit time is changed. The difference between the supply amounts before and after the change may be constant, or may be proportional to the difference between the average value calculated in step S58 and the threshold value. This difference may correspond to other values.

  In step S62, the amount of the chemical solution that is decreased by the operation of the gas valve 30 may be proportional to the difference between the average value calculated in step S58 and the threshold value, or corresponds to other values. Also good.

  In the case of the cleaning apparatus shown in FIG. 1, the mixing nozzle 18 ejects the cleaning liquid from the upper surface of the object to be cleaned 50, but the mixing nozzle 18 may eject the cleaning liquid from the lower surface of the object to be cleaned 50.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure showing the structure of the washing | cleaning apparatus which concerns on embodiment of this invention. It is a flowchart which shows the procedure of control of the prevention process of the electric charge which concerns on embodiment of this invention. It is a figure showing the structure of the washing | cleaning apparatus which concerns on the modification of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrode, 12 Ammeter, 13 Coulomb meter, 14 Calculation part, 16 Signal generation part, 18 Mixing nozzle, 20 Chemical liquid tank, 21 CO ₂ bubbler, 22 Gas tank, 24 Liquid pump, 26 Gas pump, 28 Chemical liquid valve, 30 Gas valve, 32 carbon dioxide tank, 34 carbon dioxide valve, 36 conductivity sensor, 40 recording device, 42 computer, 50 object to be cleaned, 420 interface, 422 keyboard, 424 CPU, 426 memory.

Claims (7)

Gas supply means for supplying gas;
Adjusting means for adjusting the supply amount of the gas per unit time;
Liquid supply means for supplying a liquid;
A nozzle that mixes the gas supplied by the gas supply means and the liquid supplied by the liquid supply means, and ejects a mixture of the gas and the liquid;
Detection means for detecting a corresponding amount corresponding to the charge amount of the mixture;
And a control unit for controlling the adjustment unit so as to reduce the supply amount of the gas per unit time when the absolute value of the corresponding amount is equal to or greater than a threshold value. The detection means includes
An electrode within a diffusion range of the mixture ejected from the nozzle;
Measuring means for measuring a value corresponding to the amount of electrons transferred between the mixture and the electrode;
The cleaning apparatus according to claim 1, wherein the control means includes means for feedback-controlling the adjusting means.   The cleaning apparatus according to claim 2, wherein the measurement unit includes an ammeter.   The cleaning apparatus according to claim 2, wherein the measurement unit includes a coulomb meter. The control means includes
Recording means for recording the corresponding amount;
Based on the corresponding amount recorded by the recording unit, an average calculating unit for calculating an average value of the corresponding amount;
The cleaning apparatus according to claim 1, further comprising means for controlling the adjustment means so as to reduce the supply amount of the gas per unit time when the absolute value of the average value is equal to or greater than a threshold value. The control means includes
Recording means for recording the corresponding amount;
A charge width calculating means for calculating a difference between a maximum value and a minimum value in the corresponding amount after the supply amount is last controlled among the corresponding amounts recorded by the recording unit;
And a means for controlling the adjustment means so as to reduce the supply amount of the gas per unit time when the absolute value of the difference calculated by the charging width calculation means is equal to or greater than a threshold value. The cleaning device described. An ejection step for ejecting a mixture of gas and liquid;
A detection step of detecting a corresponding amount corresponding to the charge amount of the mixture ejected in the ejection step;
And a control step of controlling the supply amount so that the supply amount of the gas per unit time decreases when the absolute value of the corresponding amount is equal to or greater than a threshold value.

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