JP4362473B2 - Chemical solution supply device and supply device - Google Patents

Description

  The present invention relates to a chemical solution supply apparatus, and in particular, a chemical solution supply apparatus that supplies a chemical solution in which a plurality of components are mixed at a predetermined ratio to a manufacturing apparatus for electronic devices such as a semiconductor manufacturing apparatus or a flat panel display (FPD) manufacturing apparatus. It is about.

  In recent years, electronic device manufacturing apparatuses such as semiconductor manufacturing apparatuses or FPD manufacturing apparatuses use various chemical solutions, for example, mixed chemical solutions manufactured by mixing a plurality of stock solutions in large quantities and frequently. For example, in the so-called CMP (Chemical Mechanical Polishing) process among the manufacturing processes, various slurries are used as the polishing liquid. The slurry is prepared by mixing a plurality of stock solutions, but sedimentation and aggregation proceed in a short time. Therefore, it is required to stably supply a mixed chemical solution such as slurry at a predetermined concentration.

  A conventional chemical solution supply apparatus weighs each stock solution and supplies it to a tank, mixes the stock solution in the tank to prepare a mixed chemical solution, and supplies the prepared mixed chemical solution to an electronic device manufacturing apparatus. The concentration of the mixed chemical solution is managed by detecting the volume and weight of the chemical solution in the tank and calculating the mixing ratio. In some cases, the concentration of the mixed chemical solution in the tank is directly measured by the concentration detector. The chemical liquid adjusted to a predetermined concentration in the tank is mixed and mixed uniformly using an inert gas such as nitrogen or a pump, and supplied to the electronic device manufacturing apparatus.

  The slurry prepared by the chemical solution supply apparatus is used in a wafer final polishing process in order to improve the flatness of the surface of the silicon wafer, for example. The wafer surface is polished by the mechanical stress and chemical action of the slurry applied between the polishing pad and the wafer.

  Undissolved substances such as abrasive grains contained in the slurry aggregate and settle due to changes over time. This aggregation and sedimentation is a problem in the manufacture of electronic devices. For example, when the agglomerated slurry is applied onto the wafer, micro scratches are formed on the wafer surface, which reduces the yield of the wafer.

  Further, the aggregation / sedimentation of the undissolved substance in the slurry changes the concentration of the mixed chemical solution. When the undissolved substance in the slurry settles in the pipe, the supply of the slurry to the electronic device manufacturing apparatus becomes unstable. Further, in order to prevent the piping from being blocked by the aggregated and settled undissolved substance, an operation for removing the aggregated and settled undissolved substance is performed. The removal operation causes a problem that the supply of slurry to the electronic device manufacturing apparatus is delayed.

  In order to prevent aggregation and sedimentation of the slurry, it can be considered that the slurry is constantly stirred. However, the agitation of the slurry increases the collision frequency between the undissolved substances, which may instead promote aggregation.

  With certain types of mixed drug solutions, the time from production to use is limited to a short time. When such a mixed chemical solution is manufactured in a tank, there is a problem that the chemical solution aggregates and settles before being supplied to the electronic device manufacturing apparatus.

An object of the present invention is to provide a chemical supply device and a supply device that can stably supply a mixed chemical solution that easily aggregates or settles.

In the first aspect of the present invention, a chemical liquid supply device is provided that supplies a chemical liquid stored in a storage tank to an external device. The apparatus includes a supply path through which the chemical liquid flows at a predetermined flow rate, and a reflux path for recirculating the chemical liquid from the supply path to the storage tank when the supply of the chemical liquid to the external device is stopped. wherein the supply path, an upstream valve that selectively opened from the storage tank to incorporate the chemical, a downstream valve that selectively opened to supply the chemical to the external device, and the upstream valve A constant pressure valve provided between the downstream valve and setting a discharge pressure of the chemical liquid, and the reflux path returns the chemical liquid from between the constant pressure valve and the downstream valve to the storage tank. .

According to a second aspect of the present invention, there is provided a chemical liquid supply apparatus that mixes a plurality of stock solutions respectively stored in a plurality of storage tanks to generate a mixed chemical liquid and supplies the mixed chemical liquid to an external device. The apparatus includes a plurality of supply paths through which the plurality of stock solutions each flow at a predetermined flow rate, and when the supply of the mixed chemical liquid to the external apparatus is stopped, the plurality of storage tanks from the plurality of supply paths wherein a plurality of stock multiple return path for returning respectively to said plurality of feed paths, respectively, the upstream valves selectively opened from the storage tank to incorporate the stock solution, the external device A plurality of reflux valves, each having a downstream valve that is selectively opened to supply the chemical liquid to the liquid crystal, and a constant pressure valve that is provided between the upstream valve and the downstream valve and sets a discharge pressure of the chemical liquid. The paths recirculate the stock solution to the storage tank from between the constant pressure valve and the downstream valve, respectively.

In the 3rd aspect of this invention, the chemical | medical solution supply apparatus which supplies a slurry to an external device is provided. The apparatus includes a first supply path through which a first liquid containing abrasive grains used for preparing the slurry therein flows at a predetermined flow rate, and the first liquid path for preparing the slurry therein. A second supply path through which the second liquid mixed with the liquid flows at a predetermined flow rate; and a reflux path connected to the first supply path. When the supply of the slurry to the external device is stopped, the reflux path causes the first liquid to reflux from the first supply path to the first storage tank. Each of the first and second supply paths includes an upstream valve that is selectively opened to take the associated liquid from the associated storage tank, and the associated liquid from each supply path to the external device. A downstream valve that is selectively opened to supply gas, and a constant pressure valve that is provided between the upstream valve and the downstream valve and sets a discharge pressure of the slurry discharged from each supply path , and The recirculation path recirculates the first liquid from between the constant pressure valve and the downstream valve to the first storage tank.

In the fourth aspect of the present invention, the first liquid and the second liquid are respectively connected to the first tank for storing the first liquid and the second tank for storing the second liquid. Thus, a supply device is provided that supplies the mixed solution to an external device while preparing the mixed solution. The apparatus includes a first supply path through which the first liquid flows, a second supply path through which the second liquid flows, a first supply path, and a second supply path. A mixer connected to mix the first liquid and the second liquid; a first constant pressure valve provided in the first supply path; for setting a discharge pressure of the first liquid; A first shutoff valve provided in one supply path for selectively shutting off the supply of the first liquid to the mixer; and in the first supply path, the first shutoff valve and the first shutoff valve A first recirculation path connecting the first pressure tank to the constant pressure valve, a first recirculation valve provided in the middle of the first recirculation path, and supply of the mixed liquid to the external device The first liquid is removed while maintaining the flow of the first liquid in the first supply path. To return to the first tank through the first return path, it closes the first shut-off valve, and a control device for opening the first recirculation valve.

  As shown in FIG. 1, the chemical liquid supply apparatus 100 according to the first embodiment of the present invention is prepared by preparing chemical liquids from chemicals respectively stored in the first storage tank 1 and the second storage tank 2. The chemical solution is supplied to the electronic device manufacturing apparatus 7.

  The first chemical stored in the first storage tank 1 (for example, a slurry stock solution such as an abrasive suspension) is pumped out by the first pump 3 and pumped to the chemical mixing device 4. A part of the first chemical pumped from the first pump 3 is returned to the first storage tank 1 in order to agitate the first chemical in the first storage tank 1.

  The second chemical stored in the second storage tank 2 (for example, a dispersion medium for diluting to be mixed with the abrasive suspension to prepare slurry) is pumped out by the second pump 5 and the chemical liquid mixing device 4. To be pumped. A part of the second chemical pumped from the second pump 5 is returned to the second storage tank 2 in order to agitate the second chemical in the second storage tank 2.

  The chemical liquid mixing device 4 includes a first supply path A that supplies the first chemical to the mixer 6 and a second supply path B that supplies the second chemical to the mixer 6. The first and second chemicals are appropriately mixed by the mixer 6 and supplied to the electronic device manufacturing apparatus 7. The mixer 6 is, for example, a static mixer.

  The first supply path A includes an upstream valve 8, a downstream valve 9, an upstream pressure gauge 10, a downstream pressure gauge 11, a first constant pressure valve 12, a first orifice (flow rate adjusting means) 13 configured by a needle valve, And it is controlled by the control apparatus 15 which contains the 1st flowmeter 14 and controls the chemical | medical solution mixing apparatus 4.

  When the upstream valve 8 is opened, the first chemical pumped from the first pump 3 is supplied to the upstream pressure gauge 10. The upstream pressure gauge 10 measures the pressure of the first chemical supplied from the upstream valve 8 and supplies the first chemical to the first constant pressure valve 12. The measured value of the upstream pressure gauge 10 is supplied to the control device 15.

The first constant pressure valve 12 reduces the pressure of the first chemical pumped from the first pump 3 to a predetermined pressure, and then supplies the first chemical to the downstream pressure gauge 11.
The downstream pressure gauge 11 measures the pressure of the first chemical supplied from the first constant pressure valve 12 and supplies the first chemical to the first orifice 13. The measured value of the downstream pressure gauge 11 is supplied to the control device 15.

  The control device 15 controls the first constant pressure valve 12 based on the measured values of the upstream and downstream pressure gauges 10 and 11 so as to maintain the pressure of the first chemical supplied to the first orifice 13 at a predetermined value. To adjust the air pressure.

  The first orifice 13 adjusts the flow rate of the first chemical supplied from the downstream pressure gauge 11 and then supplies the first chemical to the first flow meter 14. The first flow meter 14 detects the flow rate of the first chemical supplied from the first orifice 13 and supplies the detected value to the control device 15.

  In the case of preparing a cerium slurry in which the settling and agglomeration of the abrasive grains are likely to occur, that is, in the case where the first chemical is a suspension (suspension) containing abrasive grains such as cerium oxide, the first pump 3 The discharge flow rate is preferably set to 0 to 10 L / min, the discharge pressure of the first constant pressure valve 12 is set to 0 to 0.5 MPa, and the flow rate in the first orifice 13 is set to 0 to 0.5 L / min.

  The first flow meter 14 supplies the first chemical supplied from the first orifice 13 to the downstream valve 9. When the downstream valve 9 is opened, the first chemical is supplied to the mixer 6. When the downstream valve 9 is closed, the supply of the first chemical to the mixer 6 is shut off.

  The graph of FIG. 2 shows the relationship between the air pressure (horizontal axis) for adjusting the first constant pressure valve 12 and the flow rate (vertical axis) of the first chemical flowing through the first orifice 13. The relationship between the air pressure and the flow rate is changed according to the opening degree of the first orifice 13. For example, the straight line X represents the relationship when the first orifice 13 is fully opened, the straight line Y represents the relationship when the opening of the first orifice 13 is reduced to half, and the straight line Z represents the first orifice. The relationship when the flow rate of 13 is further reduced is shown.

  As shown in FIG. 2, when the first constant pressure valve 12 is operated to adjust the pressure of the first chemical, the change in the flow rate with the increase in pressure increases as the opening of the first orifice 13 increases. Become.

  In the middle of the first supply path A, a first recirculation path C that recirculates the first chemical flowing through the first supply path A to the first storage tank 1 is connected. That is, the first reflux path C connects the output side (downstream position) of the first flow meter 14 and the storage tank 1. The reflux valve 16 provided in the middle of the first reflux path C is controlled by the control device 15 and is opened when the downstream valve 9 is closed. Therefore, when the downstream valve 9 is closed, the first chemical flowing in the first supply path A is returned to the first storage tank 1 via the first reflux path C.

  The first supply path A is bypassed by the bypass path D. Specifically, the bypass path D bypasses the input side (upstream position) of the upstream valve 8 and the output side (downstream position) of the first reflux valve 16. The bypass valve 17 provided in the middle of the bypass path D is opened when the downstream valve 9 is closed, or is always kept open. The opening degree of the bypass valve 17 is adjusted so that the flow velocity in the first orifice 13 is maintained at 0 to 5 L / min.

  The second supply path B includes an upstream valve 18, a downstream valve 19, an upstream pressure gauge 20, a downstream pressure gauge 21, a second constant pressure valve 22, a second orifice (flow rate adjusting means) 23, and a second flow rate. It is controlled by a control device 15 that controls the chemical liquid mixing device 4.

  When preparing cerium slurry, the discharge pressure of the second constant pressure valve 22 is set to 0 to 0.5 MPa, and the flow rate of the second chemical flowing through the second orifice 23 is set to 0 to 0.5 L / min. Is preferred.

  In the middle of the second supply path B, a second reflux path E similar to the first reflux path C is connected. In the middle of the second reflux path E, a second reflux valve 25 that is opened when the downstream valve 19 is closed is provided.

Hereinafter, the operation of the chemical solution supply apparatus 100 will be described.
When supplying the mixed chemical solution to the electronic device manufacturing apparatus 7, the control apparatus 15 opens the upstream valves 8 and 19 and the downstream valves 9 and 19. Then, the first chemical is supplied from the first storage tank 1 to the mixer 6 via the first pump 3 and the first supply path A. The pressure and flow rate of the first chemical are controlled to a predetermined value by the first constant pressure valve 12 and the first orifice 13.

  Further, the second chemical is supplied from the second storage tank 2 to the mixer 6 through the second pump 5 and the first supply path B. The pressure and flow rate of the second chemical are controlled to a predetermined value by the second constant pressure valve 22 and the second orifice 23.

  The first chemical and the second chemical are mixed by the mixer 6 and supplied to the electronic device manufacturing apparatus 7. The mixing ratio of the mixed chemical solution is controlled by the controller 15 based on the flow rates detected by the first and second flow meters 14 and 24.

  On the other hand, when the supply of the mixed chemical solution to the electronic device manufacturing apparatus 7 is stopped, the downstream valves 9 and 19 are closed, and at the same time, the first and second reflux valves 16 and 25 are opened. Thus, the first chemical flowing through the first supply path A is returned to the first storage tank 1 via the first reflux path C. In other words, the first chemical continues to flow through the circulation path including the first storage tank 1, the first supply path A, and the first reflux path C. Similarly, the second chemical flowing through the second supply path B is returned to the second storage tank 2 via the second reflux path E. In other words, the second chemical continues to flow through the circulation path including the second storage tank 2, the first supply path B, and the second reflux path E.

  Since the flow of the first chemical is always maintained in the first supply path A, the aggregation and settling of the first chemical is prevented. Further, in the second supply path B, aggregation and sedimentation of the second chemical are prevented.

  The cerium abrasive grains in the cerium suspension tend to aggregate and settle. Therefore, when only a part of the cerium suspension flowing through the first supply path A is supplied to the first reflux path C, the cerium abrasive grains in the first reflux path C due to the insufficient flow rate in the first reflux path C. Aggregation or sedimentation may occur. In the first embodiment, the cerium suspension is supplied to the first reflux path C via the bypass path D. As a result, the flow rate of the first reflux path C is increased, and aggregation of cerium abrasive grains or sedimentation in the first reflux path C is prevented.

According to the first embodiment, the following operational effects can be obtained.
(1) According to the chemical solution supply apparatus 100, the abrasive suspension and the dispersion medium are mixed while being supplied to the mixer 6 at a predetermined flow rate to prepare a slurry. Since the prepared slurry is immediately supplied to the electronic device manufacturing apparatus 7, sedimentation and agglomeration of the slurry is prevented, and a slurry with stable quality can be supplied to the electronic device manufacturing apparatus.

  (2) When the slurry is not supplied to the electronic device manufacturing apparatus 7, the flow of the abrasive suspension in the first supply path A supplies the slurry to the electronic device manufacturing apparatus 7 by the reflux through the first reflux path C. Maintained at the same flow rate as the medium flow rate. Therefore, sedimentation and aggregation of the abrasive grains in the first supply path A can be prevented, and a slurry with stable quality can be quickly supplied to the electronic device manufacturing apparatus 7 when the supply of the slurry is resumed. Also in the second supply path B, the second reflux path E can prevent the second chemical from settling and agglomerating.

  (3) When the flow rate of the first reflux path C is small, the abrasive suspension is supplied to the first reflux path C via the bypass path D. Accordingly, the settling and aggregation of the abrasive grains in the first reflux path C can be prevented.

  (4) When the slurry is not supplied to the electronic device manufacturing apparatus 7, the flow of the abrasive suspension and the dispersion medium in the first and second supply paths A and B is caused by the return of the first and second reflux paths C and E. Is maintained at the same flow rate as that during supply of the slurry to the electronic device manufacturing apparatus 7. Accordingly, when the supply of the slurry is resumed, the time from the opening of the downstream valve 9 and the downstream valve 19 to the stabilization of the flow rates of the abrasive suspension and the dispersion medium supplied to the mixer 6 is shortened. The shortening of the restart time will be described with reference to FIGS.

  The graph of FIG. 3 shows a state where the supply of slurry to the electronic device manufacturing apparatus 7 is stopped by stopping the flow of the first and second chemicals in the first and second supply paths A and B. It is a comparative example which shows the fluctuation | variation of the flow volume at the time of restarting supply. In FIG. 4, the supply of the slurry is resumed from the state where the supply of the slurry to the electronic device manufacturing apparatus 7 is stopped while maintaining the flow of the first and second chemicals in the first and second supply paths A and B. Shows the fluctuations in the flow rate.

  In the case of the comparative example of FIG. 3, when the time required for the supply flow rate to stabilize, for example, the supply flow rate from the first supply path A is set to 200 mL / min, the error in the supply flow rate is ± 10 mL / min from the restart of supply The time required to converge within the range is about 11 seconds. This time is for adjusting the flow rate by adjusting the constant pressure valve and the orifice based on the detected values of the pressure gauge and the flow meter after the supply is resumed.

On the other hand, in this embodiment, as shown in FIG. 4, the flow rate is stabilized in about 2 seconds after resumption of supply. This is because the flow in the first and second supply paths A and B is maintained.
Next, a chemical liquid supply apparatus 200 according to the second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that a third pump 26 is provided between the mixer 6 and the electronic device manufacturing apparatus 7. The third pump 26 is preferably a pump that can appropriately adjust the discharge flow rate.

When the distance from the mixer 6 to the electronic device manufacturing apparatus 7 is long by the third pump 26, the slurry can be supplied by the third pump 26 at a stable pressure.
Next, with reference to FIG. 6, the chemical | medical solution supply apparatus 300 of 3rd Embodiment of this invention is demonstrated. The third embodiment is different from the first embodiment in that first and second cleaning valves 27 and 28 are added.

  The first supply path A can be cleaned by the cleaning valves 27 and 28. That is, the valves 8, 9, 16 are closed, and the cleaning valves 27, 28 are opened. In this state, pure water or an appropriate cleaning liquid is supplied to the first supply path A through the first cleaning valve 27 and drained through the second cleaning valve 28. In this way, it is possible to easily clean the first supply path A for supplying an abrasive suspension that tends to settle and aggregate.

If the second cleaning valve 28 is closed and the downstream valve 9 is opened, the mixer 6 and the electronic device manufacturing apparatus 7 can be cleaned.
The cleaning effect can be further improved by supplying the cleaning liquid from the second cleaning valve 28 toward the first cleaning valve 27 and flowing the cleaning liquid in the direction opposite to the flow of the abrasive suspension.

  Hereinafter, with reference to FIG. 7, the chemical | medical solution supply apparatus 400 of 4th Embodiment of this invention is demonstrated. In the fourth embodiment, two supply paths A1 and A2 are provided in parallel instead of the first supply path A of the first embodiment. The two supply paths A1 and A2 are provided with cleaning valves 29 to 32 as in the third embodiment.

  In the fourth embodiment, while the abrasive suspension is supplied to the electronic device manufacturing apparatus 7 in one of the two supply paths A1 and A2, the other path can be cleaned. Since the two supply paths A1 and A2 are cleaned every predetermined time, the abrasive suspension supply operation can be performed continuously. Further, even when the settling and agglomeration of the abrasive grains occur in the supply paths A1 and A2, the aggregated abrasive grains are periodically removed and the slurry is continuously supplied to the electronic device manufacturing apparatus 7. Can do.

The first to fourth embodiments may be modified as follows.
In the case where the second chemical flowing in the second supply path B is a uniform fluid that does not settle and aggregate like pure water, the second reflux path E may be omitted.

  When the second chemical flowing in the second supply path B is a non-uniform fluid that tends to settle and aggregate, a bypass path may be provided in the second supply path B.

It is the schematic of the chemical | medical solution supply apparatus of 1st Embodiment of this invention. It is a graph which shows the relationship between the air pressure which adjusts a constant pressure valve, and the flow volume of an orifice. It is a graph which shows the prior art example of the flow volume of an orifice at the time of the supply start of an abrasive grain. It is explanatory drawing which shows the flow volume of an orifice at the time of the supply start of the abrasive grain of 1st Embodiment. It is the schematic of the chemical | medical solution supply apparatus of 2nd Embodiment of this invention. It is the schematic of the chemical | medical solution supply apparatus of 3rd Embodiment of this invention. It is the schematic of the chemical | medical solution supply apparatus of 4th Embodiment of this invention.

Claims (14)

A chemical supply device that supplies a chemical stored in a storage tank to an external device,
A supply path through which the chemical solution flows at a predetermined flow rate;
A reflux path for refluxing the chemical from the supply path to the storage tank when the supply of the chemical to the external device is stopped;
The supply path is
An upstream valve selectively opened to take in the chemical from the storage tank;
A downstream valve that is selectively opened to supply the chemical to the external device,
A constant pressure valve that is provided between the upstream valve and the downstream valve and sets a discharge pressure of the chemical solution ;
The recirculation path is configured to recirculate the chemical liquid to the storage tank from between the constant pressure valve and the downstream valve. A chemical liquid supply device that mixes a plurality of stock solutions respectively stored in a plurality of storage tanks to generate a mixed chemical liquid, and supplies the mixed chemical liquid to an external device,
A plurality of supply paths through which the plurality of stock solutions each flow at a predetermined flow rate,
A plurality of recirculation paths for recirculating the plurality of stock solutions from the plurality of supply paths to the plurality of storage tanks when the supply of the mixed chemical liquid to the external device is stopped;
Each of the plurality of supply paths is
An upstream valve that is selectively opened to take the stock solution from the storage tank;
A downstream valve that is selectively opened to supply the chemical to the external device,
A constant pressure valve that is provided between the upstream valve and the downstream valve and sets a discharge pressure of the chemical solution ;
The plurality of reflux paths each return the stock solution to the storage tank from between the constant pressure valve and the downstream valve. A chemical supply device for supplying slurry to an external device,
A first supply path through which a first liquid containing abrasive grains used for preparing the slurry flows at a predetermined flow rate;
A second supply path through which a second liquid mixed with the first liquid in order to prepare the slurry flows at a predetermined flow rate;
A recirculation path connected to the first supply path, and when the supply of the slurry to the external device is stopped, the first liquid is recirculated from the first supply path to the first storage tank. The reflux path,
In each of the first and second supply paths,
An upstream valve that is selectively opened to take the associated liquid from the associated storage tank;
A downstream valve selectively opened to supply the associated liquid from each supply path to the external device ;
A constant pressure valve that is provided between the upstream valve and the downstream valve and sets a discharge pressure of the slurry discharged from each supply path ;
The recirculation path is configured to recirculate the first liquid to the first storage tank from between the constant pressure valve and the downstream valve. The chemical solution supply apparatus according to claim 3 , further comprising a bypass path that supplies the first liquid from the first storage tank to the reflux path in parallel with the first supply path. Wherein the each of the first and second supply path, the chemical liquid supply device according to claim 3 or 4, characterized in that flow regulating means to regulate the flow rate of each feed path is provided. It said upstream valve, by operating the pressure valve and the flow regulatory means, chemical supply according to claim 5, characterized in that the control device further comprising controlling the flow rate of the first liquid and the second liquid apparatus. A first cleaning valve for supplying a cleaning liquid to the first supply path;
The chemical liquid supply apparatus according to claim 3, further comprising a second cleaning valve that discharges the cleaning liquid from the first supply path.   The first supply path is one of at least two supply paths in parallel, and the first and second cleaning valves are provided in each of the at least two supply paths. The chemical | medical solution supply apparatus of Claim 7. Each of the first and second supply paths includes a pressure gauge that detects a pressure in the related supply path and supplies the detected value to the control device, and the control device includes the pressure gauge. The chemical solution supply device according to claim 6, wherein the constant pressure valve is controlled based on a detected value. The flow rate regulatory means comprises a a flow rate detecting the flow rate meter supplied to the control device the detected value of each path, and an orifice which is controlled by the control device based on the value detected by the flow meter The chemical | medical solution supply apparatus of Claim 6 characterized by the above-mentioned. The first tank for storing the first liquid and the second tank for storing the second liquid are connected to each other, and the first liquid and the second liquid are mixed to prepare a mixed liquid. A supply device for supplying liquid to an external device,
A first supply path through which the first liquid flows;
A second supply path through which the second liquid flows;
A mixer connected to the first supply path and the second supply path for mixing the first liquid and the second liquid;
A first constant pressure valve that is provided in the first supply path and sets a discharge pressure of the first liquid;
A first cutoff valve provided in the first supply path for selectively blocking supply of the first liquid to the mixer;
In the first supply path, a first return path that connects the first tank and between the first shut-off valve a first constant pressure valve,
A first reflux valve provided in the middle of the first reflux path;
When stopping the supply of the mixed liquid to the external device, the first liquid is supplied via the first reflux path while maintaining the flow of the first liquid in the first supply path. to return to the tank, said first closing the shutoff valve, and the supply device characterized by a control device for opening the first recirculation valve. A second constant pressure valve that is provided in the second supply path and sets a discharge pressure of the second liquid;
A second cutoff valve provided in the second supply path for selectively blocking the supply of the second liquid to the mixer;
In the second supply path, and a second circulation path that connects the second tank and between the second shut-off valve a first constant pressure valve,
A second recirculation valve provided in the middle of the second recirculation path, and when the controller stops supplying the mixed liquid to the external device, the second liquid is recirculated to the second recirculation path. The supply device according to claim 11, wherein the second shutoff valve is closed and the second reflux valve is opened in order to return to the second tank via the path. 13. The control device opens the first and second shutoff valves and closes the first and second reflux valves when supplying the mixed liquid to the external device. The supply device described in 1. The supply device according to claim 13, wherein the first liquid is a suspension containing abrasive grains, the second liquid is a diluting liquid for diluting the suspension, and the mixed liquid is a polishing slurry.

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