JP5967939B2 - Management method of liquid supply device - Google Patents

Description

  The present invention relates to a mixed liquid supply apparatus for supplying a liquid. More particularly, the present invention relates to a polishing liquid supply apparatus for supplying a polishing liquid to a polishing apparatus for polishing a workpiece such as a semiconductor wafer.

  A CMP apparatus (see Patent Document 1) for polishing a plate-like object such as a semiconductor wafer with a slurry and a polishing cloth composed of abrasive grains and a liquid and flattening the surface with high precision. An apparatus that uses a mixed liquid composed of abrasive grains and liquid such as a water jet that cuts an object by being sprayed with a liquid is provided with a mixed liquid supply apparatus (see Patent Document 2) that supplies the mixed liquid. .

  Such a mixed liquid supply apparatus normally mixes pure water and an abrasive stock solution containing a high concentration of abrasive in a mixing tank, and supplies slurry as a mixed liquid to various processing apparatuses. The slurry is adjusted according to various purposes, and as one of them, an additive is mixed to obtain an effect of promoting aggregation and dispersion of abrasive grains. Examples of the additive include hydrogen peroxide solution and silicone oil (see Patent Document 1).

JP 2001-326200 A JP 2011-143508 A

  These additives are required in a very small amount as compared with the stock abrasive solution and pure water, and in particular, the amount may be as small as 5 ml per 20 L of slurry. Currently, flow sensors that can accurately measure the flow while flowing in the pipe are in circulation, but it is important to use the flow sensor correctly in order to accurately measure. For example, there is a problem that accurate measurement of the flow rate becomes difficult due to bubbles entering the pipe. The mixing of bubbles is a case that is relatively likely to occur. For example, the bubbles may flow into the pipe only by handling the pipe inserted into the tank containing the additive from the liquid level of the additive and returning it again. This is a major problem because it is an operation that must be performed when the tank containing the additive is replaced.

  The present invention has been made in view of these points, and an object of the present invention is to provide a method for managing a liquid supply apparatus that enables accurate measurement of the liquid flow rate.

In order to solve the above-described problems and achieve the object, a method for managing a liquid supply apparatus according to the first aspect of the present invention includes a supply tank that stores a liquid and a storage tank that is supplied with the liquid in the supply tank. A supply pipe having one end inserted into the supply tank and the other end inserted into the storage tank; a pump disposed in the supply pipe and delivering the liquid to the storage tank; and a flow through the supply pipe In a liquid supply apparatus comprising a flow rate sensor for measuring the flow rate of the liquid and a liquid detection sensor disposed in the supply pipe immediately before flowing into the storage tank, one end of the supply pipe is exposed from the liquid surface A method for managing a liquid supply apparatus for preventing measurement failure of the flow sensor due to air bubbles mixed into the supply pipe when it is inserted again into the liquid later, after one end of the supply pipe is exposed from the liquid surface , One end of the supply pipe is again at the liquid level When it is input, and the liquid discharge step of all discharged by backflow of liquid in the supply pipe by the pump, after performing the liquid discharging step, the liquid suction again sucked into the feed tube the liquid by the pump And the flow sensor restarts the measurement after the liquid detection sensor detects the sucked up liquid.

  According to the management method of the liquid supply apparatus of the present invention, in a scene where gas enters the supply pipe, all the liquid in the supply pipe is once discharged and sucked again, so that the liquid is mixed in the vicinity of the suction opening of the supply pipe. Air bubbles that have been trapped can be discharged reliably and measurement errors of the flow sensor can be prevented. In addition, after the liquid detection sensor detects that the liquid that has been aspirated again has been aspirated just before the delivery destination, measurement with the flow sensor is resumed, making it possible to use a flow sensor that can detect the flow of a very small amount of liquid. There is an effect that an accurate amount of liquid can be supplied.

Drawing 1 is an explanatory view showing the composition of the liquid mixture supply device concerning an embodiment. FIG. 2 is a diagram illustrating a configuration of an additive supply unit of the mixed liquid supply apparatus according to the embodiment. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a diagram showing a flow of a management method for preventing measurement errors of the flow rate sensor due to air bubbles mixed into the supply pipe by the mixed liquid supply apparatus according to the present embodiment. FIG. 5 is a diagram illustrating a state where the supply tank of the mixed liquid supply apparatus according to the present embodiment is removed from the supply pipe. FIG. 6 is a diagram illustrating a state in which bubbles enter from one end of the supply pipe in the supply tank of the mixed liquid supply apparatus according to the present embodiment. FIG. 7 is a diagram illustrating a normal detection state of the flow rate sensor of the mixed liquid supply apparatus according to the present embodiment. FIG. 8 is a diagram illustrating a state in which bubbles have entered the detection tube of the mixed liquid supply apparatus according to the present embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

  Drawing 1 is an explanatory view showing the composition of the liquid mixture supply device concerning an embodiment. FIG. 2 is a diagram illustrating a configuration of an additive supply unit of the mixed liquid supply apparatus according to the embodiment. 3 is a cross-sectional view taken along line III-III in FIG.

  A mixed liquid supply apparatus (corresponding to a liquid supply apparatus) 1 according to the embodiment includes, for example, a liquid supplied from a liquid supply source 10 and a polishing agent stock solution 8 supplied from a polishing agent stock solution tank 3 in a mixing tank 4. A slurry (corresponding to a mixed solution) 11 produced by mixing is supplied to a processing apparatus 2 such as a CMP apparatus or a water jet. As shown in FIG. 1, the mixed liquid supply apparatus 1 includes an abrasive stock solution tank 3, a mixing tank 4 as a storage tank, a storage tank 5, an additive supply means 6, a control means 7, and the like. Has been.

In the abrasive stock solution tank 3, liquids such as pure water and acid / alkali solutions are mixed with abrasives (also called abrasive grains) such as SiO ₂ , Al ₂ O ₃ , CeO ₂ , Mn ₂ O ₃ , and diamond particles. It contains the concentrated abrasive stock solution 8 having a high concentration. Further, a discharge pipe 9 is connected to the abrasive stock solution tank 3, and the abrasive stock solution tank 3 discharges the abrasive stock solution 8 to the outside through the discharge pipe 9. The discharge pipe 9 is provided with an on-off valve 18.

  The mixing tank 4 mixes a liquid such as pure water supplied from the liquid supply source 10 with the abrasive stock solution 8 supplied from the abrasive stock solution tank 3 to produce a slurry 11. In the mixing tank 4, the abrasive stock solution 8 in the abrasive stock solution tank 3 is supplied through the pipe 12, and the liquid from the liquid supply source 10 is supplied through the pipe 13. Further, the additive 40 as a liquid in a supply tank 41 (described later) of the additive supply means 6 is supplied to the mixing tank 4. The mixing tank 4 is provided with a stirring device (not shown) inside. The mixing tank 4 stirs the slurry stock solution 8, a liquid such as pure water, and the additive 40 with a stirrer to produce and store a slurry 11 having a uniform concentration.

  The pipe 12 is provided with a pump 14 and an opening / closing valve 15 in order from the abrasive stock solution tank 3. On the other hand, the pipe 13 is provided with an on-off valve 16 and a flow rate adjusting valve 17 in order from the liquid supply source 10. A pipe 20 provided with a three-way valve 21, a pump 23, and an opening / closing valve 26 is connected to the bottom of the mixing tank 4. A branch discharge pipe 22 connected to the discharge pipe 9 is connected to the three-way valve 21, and the mixing tank 4 passes the slurry 11 to the outside via the pipe 20, the three-way valve 21, the branch discharge pipe 22 and the discharge pipe 9. Discharge.

  The storage tank 5 stores the slurry 11 produced in the mixing tank 4 before supplying it to the processing apparatus 2. The storage tank 5 is supplied with the slurry 11 via the pipe 20. The storage tank 5 accommodates the supplied slurry 11.

  A pipe 30 is connected to the bottom of the storage tank 5, and the storage tank 5 supplies the slurry 11 to the processing apparatus 2 through the pipe 30. The pipe 30 is provided with a three-way valve 32 and a pump 33 in order from the storage tank 5. A branch discharge pipe 36 connected to the discharge pipe 9 is connected to the three-way valve 32, and the storage tank 5 passes the slurry 11 to the outside via the pipe 30, the three-way valve 32, the branch discharge pipe 36 and the discharge pipe 9. Discharge.

  The additive supply means 6 supplies (drops) the additive 40 as a liquid to the mixing tank 4. The additive 40 is added in a small amount to the slurry 11 to promote the aggregation and dispersion of the abrasive grains. For example, several cc of additive 40 is added to several liters of slurry 11. As an additive, hydrogen peroxide water, silicone oil, or the like can be used.

  As shown in FIG. 2, the additive supply means 6 includes a supply tank 41, a supply pipe 42, a pump 43, a flow rate sensor 44, a liquid detection sensor 45, and a liquid level detection sensor 46. ing.

  The supply tank 41 contains the additive 40. The supply pipe 42 has one end 42 a inserted into the supply tank 41 and the other end inserted into the mixing tank 4. The supply pipe 42 is made of a light transmissive material. The pump 43 is disposed in the middle of the supply pipe 42 and sends the additive 40 in the supply tank 41 to the mixing tank 4. The pump 43 can also cause the additive 40 in the supply pipe 42 to flow backward to the supply tank 41.

  The flow sensor 44 is disposed in the middle of the supply pipe 42 and measures the flow rate of the additive 40 flowing through the supply pipe 42. As shown in FIGS. 7 and 8, the flow sensor 44 includes a housing 47 and a detection tube 48 disposed in the housing 47 and connected to the supply tube 42. The flow rate sensor 44 is a so-called Coriolis type flow rate sensor that measures the twist angle of the detection tube 48 by the Coriolis force generated according to the flow rate of the additive 40. The flow sensor 44 outputs information indicating the twist angle of the detection tube 48, that is, the flow rate of the additive 40 flowing in the supply tube 42 to the control means 7.

  The liquid detection sensor 45 measures whether or not the additive 40 is flowing in the supply pipe 42 immediately before flowing into the mixing tank 4. The liquid detection sensor 45 is disposed in the supply pipe 42 immediately before flowing into the mixing tank 4. As shown in FIG. 3, the liquid detection sensor 45 includes a housing 50 attached to the supply pipe 42 by a fixing bracket 49, and a light emitting element 51 and a light receiving element 52 disposed in the housing 50. Yes. The light emitting element 51 and the light receiving element 52 are opposed to each other. The liquid detection sensor 45 is a so-called optical liquid detection sensor that measures the intensity of light emitted from the light emitting element 51 and received by the light receiving element 52 through the supply tube 42. The liquid detection sensor 45 provides the control means 7 with information indicating the intensity of light received by the light receiving element 52, that is, information indicating whether or not the additive 40 is flowing in the supply pipe 42 immediately before flowing into the mixing tank 4. Output.

  The liquid level detection sensor 46 detects the position of the liquid level 40 a of the additive 40 in the supply tank 41. The liquid level detection sensor 46 has a proximal end portion attached to the upper portion of the supply tank 41 and a distal end portion inserted into the supply tank 41. The liquid level detection sensor 46 is a so-called capacitance type liquid level detection sensor that measures the difference between the dielectric constant of the additive 40 in the supply tank 41 and the dielectric constant of air. The liquid level detection sensor 46 controls information indicating the difference between the dielectric constant of the additive 40 in the supply tank 41 and the dielectric constant of air, that is, information indicating the position of the liquid level 40a of the additive 40 in the supply tank 41. 7 is output.

  Further, the discharge pipe 9, the pipes 12, 13, 20, and 30, the branch discharge pipes 22 and 36, the on-off valves 15, 16, 18, and 26, the flow control valve 17, the three-way valves 21 and 32, and the pumps 14, 23, 43, tanks 3, 4, 5, and 41, supply pipe 42, flow rate sensor 44, and liquid level detection sensor 46 have chemical resistance.

  The control means 7 controls the above-described components constituting the mixed liquid supply apparatus 1 and the additive supply means 6, respectively. Further, the control means 7 causes the mixed liquid supply apparatus 1 to perform the operation of supplying the slurry 11 to the processing apparatus 2. Further, the control means 7 causes the additive supply means 6 to perform the operation of supplying the additive 40 to the mixing tank 4 and causes the mixed liquid supply apparatus 1 to perform the operation of producing the slurry 11. Note that the control means 7 is mainly composed of an arithmetic processing unit constituted by a CPU or the like, and a microprocessor (not shown) provided with a ROM, a RAM, etc., and a display means for displaying the state of the supply operation, and an operator works It is connected to an operating means used when registering the content information and an informing means for notifying the operator of the abnormality.

  Next, the supply operation | movement of the slurry 11 with respect to the processing apparatus 2 of the liquid mixture supply apparatus 1 which concerns on this embodiment is demonstrated. The control means 7 opens the on-off valves 15 and 16, opens the flow rate control valve 17 at a predetermined opening degree, and drives the pump 14 and the pump 43. The control means 7 supplies a predetermined amount of the abrasive stock solution 8 from the abrasive stock solution tank 3 to the mixing tank 4, supplies a predetermined amount of liquid such as pure water from the liquid supply source 10 to the mixing tank 4, and also supplies a predetermined amount. The additive 40 is supplied from the supply tank 41 to the mixing tank 4. At this time, the control means 7 controls the amount of the additive 40 supplied to the mixing tank 4 by controlling the pump 43 based on the information detected by the flow sensor 44. The control means 7 drives the stirring device in the mixing tank 4 to mix a liquid such as pure water, the abrasive stock solution 8 and the additive 40 to produce the slurry 11.

  Thereafter, the control means 7 controls the opening direction of the three-way valve 21, opens the on-off valve 26, drives the pump 23, and supplies the slurry 11 in the mixing tank 4 to the storage tank 5. Thus, the slurry 11 is temporarily stored in the storage tank 5. Further, the control means 7 controls the opening direction of the three-way valve 32, drives the pump 33, and supplies the slurry 11 in the storage tank 5 to the processing device 2 via the pipe 30. Moreover, the control means 7 performs preparation of the slurry 11 in the mixing tank 4, and supply of the slurry 11 from the mixing tank 4 to the storage tank 5 as needed.

  Next, a management method of the mixed liquid supply apparatus 1 for preventing measurement failure of the flow sensor 44 due to air bubbles mixed into the supply pipe 42 of the mixed liquid supply apparatus 1 according to the present embodiment will be described. FIG. 4 is a diagram showing a flow of a management method for preventing measurement errors of the flow rate sensor due to air bubbles mixed into the supply pipe by the mixed liquid supply apparatus according to this embodiment. FIG. 5 is a diagram illustrating a state where the supply tank of the mixed liquid supply apparatus according to the present embodiment is removed from the supply pipe. FIG. 6 is a diagram illustrating a state in which bubbles enter from one end of the supply pipe in the supply tank of the mixed liquid supply apparatus according to the present embodiment. FIG. 7 is a diagram illustrating a normal detection state of the flow rate sensor of the mixed liquid supply apparatus according to the present embodiment. FIG. 8 is a diagram illustrating a state in which bubbles have entered the detection tube of the mixed liquid supply apparatus according to the present embodiment.

  In the mixed liquid supply apparatus 1 according to the present embodiment, when the additive 40 in the supply tank 41 is reduced, the supply tank 41 is replaced with a new supply tank 41 containing a sufficient amount of the additive 40. At the time of replacement, after removing the supply tank 41 in which the additive 40 is reduced from the one end 42 a of the supply pipe 42, the supply tank 41 containing a sufficient amount of the additive 40 is attached to the one end 42 a of the supply pipe 42. . Further, in the mixed solution supply apparatus 1, the supply tank 41 may be attached to the one end 42 a of the supply pipe 42 after the supply tank 41 is removed from the one end 42 a of the supply pipe 42 and the operator confirms the inside of the supply tank 41. At the time of the exchange, as shown in FIG. 5, the bubbles K are mixed into the supply pipe 42 from the one end 42a. Further, in the mixed liquid supply apparatus 1, when the additive 40 in the supply tank 41 is almost gone and the one end 42a of the supply pipe 42 is exposed from the liquid level 40a of the additive 40, as shown in FIG. The bubbles K are mixed into the supply pipe 42.

  In short, in the mixed liquid supply apparatus 1, when one end 42 a of the supply pipe 42 is exposed from the liquid level 40 a of the additive 40 and then inserted into the additive 40 again, bubbles K are mixed from the one end 42 a into the supply pipe 42. As shown in FIG. 8, when the mixed bubble K reaches the detection tube 48, the flow rate sensor 44 causes a measurement failure that makes it difficult to accurately measure the flow rate of the additive 40 in the supply tube 42. .

  First, when the supply tank 41 is removed from one end 42 a of the supply pipe 42, the control means 7 prohibits the flow rate sensor 44 from measuring the flow rate of the additive 40 in the supply pipe 42, and the supply tank 41 is connected to one end of the supply pipe 42. It is determined whether or not it is attached to 42a again (step ST1 in FIG. 4). Next, when the control means 7 determines that the supply tank 41 is attached to the one end 42a of the supply pipe 42 again (Yes in step ST1), the control means 7 discharges the additive 40 in the supply pipe 42 into the supply tank 41. Then, the pump 43 is driven (step ST2). At this time, the control means 7 drives the pump 43 for a time sufficient to discharge all of the additive 40 in the supply pipe 42 to the supply tank 41. In this way, in step ST2, after one end 42a of the supply pipe 42 is exposed from the liquid surface 40a of the additive 40, the additive 40 in the supply pipe 42 is caused to flow backward by the pump 43 and discharged to the supply tank 41. This corresponds to the discharge step. If the control unit 7 determines that the supply tank 41 is not attached to the one end 42a of the supply pipe 42 (No in step ST1), the control unit 7 performs steps until the supply tank 41 is attached to the one end 42a of the supply pipe 42 again. Repeat ST1.

  After performing step ST2, the control means 7 drives the pump 43 so that the additive 40 in the supply tank 41 is again sucked into the supply pipe 42 (step ST3). As described above, step ST3 corresponds to a liquid suction step in which the additive 40 in the supply tank 41 is again sucked into the supply pipe 42 by the pump 43 after performing step ST2 corresponding to the liquid discharge step. Then, the additive 40 in the supply tank 41 moves in the supply pipe 42 toward the mixing tank 4.

  Next, the control means 7 determines whether or not the additive 40 is flowing in the supply pipe 42 immediately before flowing into the mixing tank 4 based on the information from the liquid detection sensor 45 (step ST4). When the control means 7 determines that the additive 40 is flowing in the supply pipe 42 immediately before flowing into the mixing tank 4 (Yes in step ST4), the control means 7 stops the pump 43, and the addition in the supply pipe 42 by the flow rate sensor 44 is performed. The flow measurement of the agent 40 is resumed (step ST5). When the control means 7 determines that the additive 40 does not flow in the supply pipe 42 immediately before flowing into the mixing tank 4 (No in step ST4), the control means 7 adds the additive to the supply pipe 42 immediately before flowing into the mixing tank 4. Step ST4 is repeated until 40 flows. As described above, step ST4 and step ST5 correspond to a measurement restarting step for restarting the measurement of the flow rate sensor 44 after the liquid detection sensor 45 detects the additive 40 sucked up in the supply pipe 42. Thus, in step ST4 and step ST5, in the mixed liquid supply apparatus 1, the flow rate sensor 44 restarts the measurement after the liquid detection sensor 45 detects the additive 40 sucked up in the supply pipe 42.

  As described above, according to the management method of the mixed liquid supply apparatus 1 according to the present embodiment, in the scene where the bubbles K enter the supply pipe 42, all the additive 40 in the supply pipe 42 is once stored in the supply tank 41. The additive 40 is sucked from the supply tank 41 again. For this reason, the bubble K mixed in the vicinity of the one end 42a of the supply pipe 42 is surely discharged out of the supply pipe 42, so that it is always added into the detection pipe 48 of the flow rate sensor 44 as shown in FIG. Filled with agent 40. Therefore, according to the management method of the mixed liquid supply apparatus 1, it is possible to prevent measurement failure of the flow rate sensor 44. Further, according to the management method of the mixed liquid supply apparatus 1, after the liquid suction sensor 45 detects that the additive 40 sucked again is sucked up to just before the delivery destination mixing tank 4, the measurement by the flow sensor 44 is resumed. . For this reason, it becomes possible to utilize the flow rate sensor 44 capable of detecting the flow rate of a very small amount of the additive 40, and it is possible to supply an accurate amount of the additive 40.

  In the above-described embodiment, the liquid supply source 10, the abrasive stock solution tank 3, the mixing tank 4, the storage tank 5, and the processing device 2 are connected as described above by the pipes 12, 20, 13, and 30. In the present invention, the present invention is not limited to this, and the connection state of the liquid supply source 10, the abrasive stock solution tank 3, the mixing tank 4, the storage tank 5, the processing device 2, and the like within a range in which the gist of the present invention can be realized. May be changed as appropriate.

  Moreover, in embodiment mentioned above, although the liquid mixture supply apparatus 1 which supplies the additive 40 as a liquid in the mixing tank 4 is used, this invention is not limited to this, It uses for various uses. Of course, the present invention may be applied to a liquid supply apparatus that supplies various liquids to a storage tank. The present invention also provides a polishing liquid supply apparatus (mixed liquid) for supplying a polishing liquid (corresponding to a mixed liquid) to a polishing apparatus (corresponding to the processing apparatus 2) that polishes a workpiece such as a semiconductor wafer. It is desirable to apply it to the supply device 1).

  Furthermore, in the present invention, the flow rate sensor is not limited to the Coriolis type flow rate sensor, and various types of flow rate sensors such as an ultrasonic type and an electromagnetic type may be used. In particular, the present invention is effective when an ultrasonic type or electromagnetic type flow sensor that is liable to cause measurement failure due to the bubble K is used. In the present invention, the liquid level detection sensor is not limited to the capacitance type liquid level detection sensor, and various types of liquid level detection sensors may be used. As the liquid detection sensor, an optical liquid detection sensor may be used. Not limited to this, various types of liquid detection sensors may be used. Furthermore, in the above-described embodiment, the capacitive liquid level detection sensor 46 immersed in the additive 40 in the supply tank 41 is used as the liquid level detection sensor. However, in the present invention, a capacitive liquid level detection sensor arranged outside the supply tank 41 without being immersed in the additive 40 may be used as the liquid level detection sensor. In this case, the liquid level detection sensor is desirably arranged on both sides of the supply tank 41 so that the height of the liquid level 40a to be detected can be detected. Further, in this case, since the liquid level detection sensor does not come into contact with the additive 40, the liquid level detection sensor can be used even when the types of the additive 40 and the slurry 11 are changed or the additive 40 and the slurry 11 are altered. Need not be cleaned each time.

  In the embodiment described above, when the supply tank 41 is attached to the one end 42a of the supply pipe 42, the flow shown in FIG. 4 is executed. However, in the present invention, the present invention is not limited to this. The flow shown in FIG. 4 may be executed by the operation of the operator. Furthermore, in the embodiment described above, when the supply tank 41 is removed from the one end 42a of the supply pipe 42 and then attached again, the flow shown in FIG. 4 is executed. However, in the present invention, the flow shown in FIG. 4 may be executed even when the additive 40 is supplied to the supply tank 41 that is still attached to the one end 42 a of the supply pipe 42. In short, the case where one end 42a of the supply pipe 42 is inserted into the liquid again after being exposed from the liquid surface 40a in the present invention refers to the case where the bubble K enters from the one end 42a of the supply pipe 42.

1 Liquid mixture supply device (liquid supply device)
4 Mixing tank (storage tank)
40 Additive (Liquid)
40a Liquid level 41 Supply tank 42 Supply pipe 42a One end 43 Pump 44 Flow rate sensor 45 Liquid detection sensor K Bubble ST2 Liquid discharge step ST3 Liquid suction step

Claims (1)

A supply tank containing liquid, a storage tank to which the liquid in the supply tank is supplied, a supply pipe having one end inserted into the supply tank and the other end inserted into the storage tank, and arranged in the middle of the supply pipe A pump installed to send the liquid to the storage tank, a flow rate sensor for measuring the flow rate of the liquid flowing in the supply pipe, and a liquid detection sensor disposed in the supply pipe just before flowing into the storage tank In the liquid supply device comprising A management method,
A liquid discharge step for discharging all of the liquid in the supply pipe backflowed by the pump when one end of the supply pipe is inserted into the liquid level again after one end of the supply pipe is exposed from the liquid level ;
A liquid suction step for sucking the liquid again into the supply pipe by the pump after performing the liquid discharge step,
The method of managing a liquid supply apparatus, wherein the flow rate sensor restarts measurement after the liquid detection sensor detects the liquid sucked up.

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