CN1713967B - Liquid medicine supply device - Google Patents

Abstract

A chemical liquid supply device (100) for supplying a slurry to an external device (7) is provided with: a supply path (A) through which the abrasive grain suspension flows at a predetermined flow rate, and a return path (C) connecting the supply path and the reservoir tank (1). When the supply of the slurry to the external apparatus is stopped, the flow of the abrasive suspension in the supply path is maintained to prevent aggregation and sedimentation of the abrasive, and the abrasive suspension is returned from the supply path to the storage tank via the return path.

Description

Liquid medicine supply device

technical field

The present invention relates to a chemical solution supply device, and more particularly, to a chemical solution supply device for supplying a chemical solution mixed with a plurality of components at a predetermined ratio in a manufacturing device of electronic devices such as a semiconductor manufacturing device or a flat panel display (FDP) manufacturing device.

Background technique

In recent years, in electronic device manufacturing apparatuses such as semiconductor manufacturing apparatuses and FDP manufacturing apparatuses, various chemical solutions are frequently used in large quantities, for example, mixed chemical solutions produced by mixing a plurality of stock solutions are used. For example, in a manufacturing process, various slurries are used as a polishing liquid in a so-called CMP (Chemical Mechanical Polishing) process. The slurry is prepared by mixing various original liquids, and settles and coagulates in a short time. Therefore, it is required to stably supply a slurry-type mixed chemical solution at a predetermined concentration.

The existing liquid medicine supply device weighs each raw liquid and supplies it to a storage tank, mixes the raw liquids in the storage tank to prepare a mixed liquid, and supplies the prepared mixed liquid to an electronic device manufacturing device. The concentration of the mixed drug solution is controlled by detecting the volume and weight of the drug solution in the storage tank and calculating the mixing ratio, and sometimes the concentration of the mixed drug solution in the storage tank is directly measured by a concentration detection device. Mix and mix the chemical solution adjusted to the specified concentration in the storage tank with inert gas such as nitrogen or a pump, and then supply it to the electronic device manufacturing device.

For example, in order to improve the flatness of the surface of a silicon wafer, a slurry prepared by a chemical solution supply device is used in the wafer finish polishing process. The surface of the wafer is ground by mechanical stress and chemical action of the slurry coated between the polishing pad and the wafer.

Undissolved substances such as abrasive grains contained in the slurry coagulate and settle over time, and such coagulation and sedimentation become a problem in the manufacture of electronic devices. For example, once the condensed slurry is coated on the wafer, it can form fine scratches on the surface of the wafer, thereby reducing the yield of the wafer.

Coagulation and sedimentation of undissolved substances in the slurry change the concentration of the mixed liquid medicine. When undissolved substances in the slurry settle in the liquid distribution pipe, the supply of the slurry to the electronic device manufacturing apparatus becomes unstable. In addition, in order to prevent clogging of the dispensing pipe by undissolved substances that have aggregated or settled, it is necessary to remove the undissolved substances that have aggregated and settled, and this cleaning operation will delay the supply of slurry to the electronic device manufacturing equipment.

In order to prevent the coagulation and settlement of the slurry, it is considered to keep stirring the slurry. However, the stirring of the slurry will increase the collision frequency of undissolved substances with each other, which may promote coagulation instead.

In a certain mixed liquid medicine, the time from its manufacture to its use is limited to a short time. When such a mixed chemical solution is produced in a storage tank, there is a problem that the chemical solution aggregates and settles until it is supplied to an electronic device manufacturing apparatus.

disclosure of invention

An object of the present invention is to provide a chemical solution supply device capable of stably supplying a mixed chemical solution that is prone to coagulation or sedimentation.

According to a first aspect of the present invention, there is provided a chemical solution supply device for supplying a chemical solution stored in a storage tank to an external device. The device includes: a supply path through which the medical fluid flows at a prescribed flow rate; and returning the medical fluid from the supply path to the storage tank when the supply of the medical fluid to the external device is stopped. in the return path.

According to a second aspect of the present invention, there is provided a medical solution supply device that mixes a plurality of stock solutions respectively stored in a plurality of storage tanks to generate a mixed medical solution and supplies the mixed medical solution to an external device. The device includes: causing the plurality of stock solutions to flow through the plurality of supply paths at predetermined flow rates; and causing the plurality of stock solutions to respectively flow back from the plurality of supply paths when the supply of the mixed chemical solution to the external device is stopped. A plurality of return flow paths into the plurality of storage tanks.

According to a third aspect of the present invention, there is provided a chemical solution supply device for supplying slurry to an external device. The device includes: a first supply path through which a first liquid containing abrasive grains used for preparing the slurry flows at a prescribed flow rate; a second supply path for mixing with the first liquid for preparing the slurry; a second supply path through which the liquid flows at a prescribed flow rate; and a return path connected to the first supply path, which makes the first liquid flow when the supply of the slurry to the external device is stopped. Return flow from the first supply path to the first storage tank.

According to a fourth aspect of the present invention, there is provided a liquid supply device for supplying the mixed liquid to an external device, the liquid supply device is respectively connected to a first storage tank for storing the first liquid and a second storage tank for storing the second liquid, The first liquid and the second liquid are mixed to prepare the mixed liquid. The liquid supply device includes: a first supply path through which the first liquid flows; a second supply path through which the second liquid flows; connected to the first supply path and the second path and a mixer for mixing the first liquid and the second liquid; a first cut-off flow provided on the first supply path for selectively cutting off the supply of the first liquid to the mixer a valve; a first return path connecting an upstream position of the first stop valve and the first storage tank on the first supply path; a first return valve disposed in the middle of the first return path; and a control device that closes the first shutoff valve and opens the first return valve when the supply of the mixed liquid to the external device is stopped, so as to maintain the The flow of the first liquid simultaneously returns the first liquid to the first storage tank via the first return path.

In addition, the present invention also provides a medical solution supply device which mixes the first and second stock solutions respectively stored in the first and second storage tanks to generate a mixed drug solution, and supplies the mixed drug solution to the outside The medical solution supply device of the device is characterized by comprising: first and second supply paths, the first and second raw liquids respectively flow in the first and second supply paths at predetermined flow rates; the first and second Two flow regulating devices, which are respectively arranged on the first and second supply paths to adjust the flow of the first and second supply paths; first and second return paths, which are respectively connected to the first and at a position between the first and second flow rate regulators and the external device on the second supply path, when the supply of the mixed chemical solution to the external device is stopped, the first and second The two raw liquids flow back from the first and second supply paths into the first and second storage tanks respectively, and the first and second supply paths will stop supplying the mixed liquid to the external device. The flow rates of the first and second raw liquids in the feed are maintained at the same flow rates as the flow rates when the mixed medical solution is being supplied.

In addition, the present invention also provides a medical solution supply device that mixes the first liquid and the second liquid respectively stored in the first and second storage tanks to form a slurry, and supplies the slurry to an external device. , characterized by comprising: a first supply path, in which the first liquid containing abrasive grains for preparing the slurry flows at a prescribed flow rate; a second supply path, which is connected with the first liquid for preparing the slurry The second liquid mixed with a liquid flows in it at a specified flow rate; first and second flow regulating devices are respectively arranged on the first and second supply paths, and are used to control the The flow rates of the first liquid and the second liquid flowing in the second supply path; first and second return paths, which are respectively connected to the first and second flow rates on the first and second supply paths At a position between the adjustment device and the external device, when the supply of the slurry to the external device is stopped, the first liquid and the second liquid are respectively returned from the first and second supply paths to the the first and second storage tanks, and when the supply of the slurry to the external device is stopped, the flow rates of the first liquid and the second liquid in the first and second supply paths are maintained to be the same as those being supplied to the external device. The flow rate is the same as the flow rate when the external device supplies the slurry.

In addition, the present invention also provides a liquid supply device for supplying the mixed liquid to an external device, the liquid supply device is respectively connected with a first storage tank for storing the first liquid and a second storage tank for storing the second liquid, and the first A liquid is mixed with the second liquid to prepare the mixed liquid; it is characterized in that it includes: making the first liquid flow through the first supply path at a prescribed flow rate; making the second liquid flow at a prescribed flow rate a second supply path flowing therethrough; a mixer connected to the first supply path and the second path for mixing the first liquid and the second liquid; disposed on the first supply path The first shut-off valve used to selectively cut off the supply of the first liquid to the mixer; the first shut-off valve provided on the second supply path to selectively cut off the supply of the second liquid to the mixer A second cut-off valve for liquid; respectively arranged at upstream positions of the first and second cut-off valves on the first and second supply paths, for controlling The first and second flow regulating devices for the flow of the first liquid and the second liquid flowing in the medium; the first return path, which is located on the first supply path upstream of the first shut-off valve and The position downstream of the first flow regulating device is connected to the first storage tank, and when the supply of the mixed liquid to the external device is stopped, the first flow rate before mixing with the second liquid is removed. A flow rate of the first liquid in a supply path is maintained at the same flow rate as when it is being supplied to the external device; a first return valve provided in the middle of the first return path; and a control device, the When the control device stops supplying the mixed liquid to the external device, it closes the first stop valve and opens the first return valve, so that the flow rate of the first liquid in the first supply path The same flow rate as the flow rate when being supplied to the external device is maintained, and the first liquid in the first supply path is returned to the first storage tank via the first return path.

A brief description of the drawings

FIG. 1 is a schematic diagram of a chemical solution supply device according to a first embodiment of the present invention.

Fig. 2 is a graph showing the relationship between the air pressure of the constant pressure valve and the flow rate of the orifice.

Fig. 3 is a graph of a conventional example of the flow rate of the orifice when the supply of abrasive grains is started.

4 is an explanatory diagram of the flow rate of the orifice when the supply of abrasive grains is started according to the first embodiment.

5 is a schematic diagram of a chemical solution supply device according to a second embodiment of the present invention.

6 is a schematic diagram of a chemical solution supply device according to a third embodiment of the present invention.

Fig. 7 is a schematic diagram of a chemical solution supply device according to a fourth embodiment of the present invention.

The best way to practice the invention

As shown in Figure 1, the medical solution supply device 100 of the first embodiment of the present invention prepares the medical solution from the medicines respectively stored in the first storage tank 1 and the second storage tank 2; Device manufacturing device 7 .

The first medicine stored in the first storage tank 1 (for example, a slurry stock solution such as abrasive particle suspension) is pumped out by the first pump 3 and sent to the medicine-liquid mixing device 4 by pressure. In order to stir the first chemical in the first storage tank 1 , a part of the first chemical pumped by the first pump 3 is returned to the first storage tank 1 .

The second chemical stored in the second storage tank 2 (for example, a dilution dispersion medium for mixing with the abrasive suspension to prepare a slurry) is pumped out by the second pump 5 and sent to the chemical-liquid mixing device 4 by pressure. In order to stir the second chemical in the second storage tank 2 , a part of the second chemical pumped by the second pump 5 is returned to the second storage tank 2 .

The chemical solution mixing device 4 includes a first supply path A for supplying the first chemical to the mixer 6 and a second supply path B for supplying the second chemical to the mixer 6 . The mixer 6 properly mixes the first and second chemicals, and then supplies them 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 adjustment mechanism) 13 composed of a needle valve, and a second pressure gauge. A flow meter 14; the first supply path A is controlled by the control device 15 which controls the liquid medicine mixing device 4.

When the upstream valve 8 is opened, the first medicine sent by the first pump 3 is supplied to the upstream pressure gauge 10; the upstream pressure gauge 10 measures the pressure of the first medicine supplied by the upstream valve 8, and then the first medicine is supplied to the first medicine. A 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 by 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 .

In order to maintain the pressure of the first medicine supplied to the first orifice 13 at a specified value, the control device 15 adjusts the air pressure used to control the first constant pressure valve 12 according to the measured values of the upstream and downstream pressure gauges 10 and 11 .

The first orifice 13 supplies the first chemical to the first flowmeter 14 after adjusting the flow rate of the first chemical supplied from the downstream pressure gauge 11 . 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 that is prone to sedimentation and aggregation of abrasive grains, that is, when the first chemical contains a suspension of abrasive grains such as cerium oxide, it is preferable to set the discharge flow rate of the first pump 13 to The discharge pressure of the first constant pressure valve 12 is set at 0-0.5 MPa, and the flow rate at the first orifice 13 is set at 0-0.5 L/min.

The first flowmeter 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 drug is supplied to the mixer 6 . When the downstream valve 9 is closed, the supply of the first chemical to the mixer 6 is cut off.

The graph in FIG. 2 shows the relationship between the air pressure (horizontal axis) used to adjust the first constant pressure valve 12 and the flow rate of medicine flowing through the first orifice 13 (vertical axis). The relationship between air pressure and flow varies with the degree of opening 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 degree of the first orifice 13 is reduced to half, and the straight line Z represents the flow rate of the first orifice 13. The relationship when zooming out further.

As shown in FIG. 2 , when the first constant pressure valve 12 is operated to adjust the pressure of the first drug, the greater the opening degree of the first orifice 13 is, the greater the change in the flow rate will be with the increase of the pressure.

In the middle of the first supply path A, a first return path C for returning the first medicine flowing through the first supply path A to the first storage tank 1 is connected. That is, the first return path C connects the output side (downstream position) of the first flowmeter 14 and the storage tank 1 . The control device 15 controls the return valve 16 provided in the middle of the first return path C to open when the downstream valve 9 is closed. Therefore, when the downstream valve 9 is closed, the first drug flowing through the first supply path A flows back into the first storage tank 1 after passing through the first return path C.

The first supply path A is bypassed by the bypass path D. In detail, the bypass path D bypasses the input side (upstream position) of the upstream valve 8 and the output side (downstream position) of the first return valve 16 . When the downstream valve 9 is closed, the bypass valve 17 provided on the way of the bypass path D is opened or kept in a normally open state. Adjust the opening degree of the bypass valve 17 to keep the flow rate at the first orifice 13 at 0-5 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 adjustment mechanism) 23 and a second flowmeter 24 ; The control device 15 that controls the chemical solution mixing device 4 controls the second supply path B.

In the case of preparing cerium slurry, it is best to set the discharge pressure of the second constant pressure valve 22 to 0-0.5 MPa, and set the flow rate of the second chemical flowing through the second orifice 23 to 0-0.5 L /min.

On the way of the second supply path B, a second return path E similar to the first return path C is connected. On the way of the second return path E, a second return valve 25 that opens when the downstream valve 19 is closed is provided.

Next, the operation of the chemical solution supply device 100 will be described.

The control device 15 opens the upstream valves 8 and 19 and the downstream valves 9 and 19 when the mixed chemical solution is supplied to the electronic device manufacturing apparatus 7 . Thus, the first medicine is sent to the mixer 6 from the first storage tank 1 through the first pump 3 and the first supply path A; the first constant pressure valve 12 and the first orifice 13 combine the pressure of the first medicine and The flow rate is controlled at the specified value.

In addition, the second medicine is sent from the second storage tank 2 to the mixer 6 through the second pump 5 and the first supply path B; the second constant pressure valve 22 and the second orifice 23 control the pressure and flow rate of the second medicine controlled at the specified value.

The mixer 6 mixes the first medicine and the second medicine, and then sends them to the electronic device manufacturing apparatus 7 . The control device 15 controls the mixing ratio of the mixed medical solution according to the flow rates detected by the first and second flowmeters 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, 19 are closed, and the first and second return valves 16, 25 are simultaneously opened. In this way, the first medicine flowing through the first supply path A flows back to the first storage tank 1 through the first return path C. In other words, the first medicine continues to flow in the circulation path constituted by the first storage tank 1 , the first supply path A, and the first return path C. Likewise, the second drug flowing through the second supply path B flows back into the second storage tank 2 through the second return path E. In other words, the second chemical continues to flow in the circulation path formed by the second storage tank 2 , the first supply path B, and the second return path E.

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

The cerium abrasive grains in the cerium suspension are easy to coagulate and settle. Therefore, when only a part of the cerium suspension flowing through the first supply path A is supplied to the first return path C, due to the flow rate in the first return path C Insufficient, in the first return path C, the aggregation or sedimentation of cerium abrasive grains may occur. In a first embodiment, the cerium suspension is supplied to the first return path C via the bypass path D. Therefore, the flow rate of the first return path C is increased, and the occurrence of aggregation or sedimentation of the cerium abrasive grains in the first return path C is prevented.

According to the first embodiment, the following effects are obtained.

(1) According to the chemical supply device 100 , the abrasive suspension and the dispersion medium are supplied to the mixer 6 at a predetermined flow rate and mixed to prepare a slurry. The prepared slurry is directly sent to the electronic device manufacturing apparatus 7, so that the sedimentation and aggregation of the slurry can be prevented, and the stable quality slurry can be supplied to the electronic device manufacturing apparatus.

(2) When the slurry is not being supplied to the electronic device manufacturing apparatus 7, the flow of the abrasive grain suspension is maintained in the first supply path A by the return flow through the first return flow path C and is being supplied to the electronic device manufacturing apparatus 7. The flow rate is the same as the flow rate when the slurry is supplied. Therefore, the sedimentation and aggregation of the abrasive grains in the first supply path A can be prevented, and at the same time, when the slurry supply is restarted, the slurry with stable quality can be quickly supplied to the electronic device manufacturing apparatus 7 . In addition, in the second supply path B, the second return path E can be used to prevent sedimentation and aggregation of the second chemical.

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

(4) When the slurry is not being supplied to the electronic device manufacturing apparatus 7, the abrasive grain suspension and the dispersion medium in the first and second supply paths A, B are reflowed by means of the first and second return paths C, E. The liquid flow is kept at the same flow rate as the flow rate when the slurry is being supplied to the electronic device manufacturing apparatus 7 . Therefore, when the slurry supply is restarted, the time from opening the downstream valve 9 and the downstream valve 19 to stabilizing the flow rates of the abrasive suspension and the dispersion medium supplied to the mixer 6 can be shortened. Next, the shortening of the restart time will be described with reference to FIGS. 3 and 4 .

What the graph of FIG. 3 shows is a comparative example, showing the state of stopping the supply of the slurry to the electronic device 7 due to stopping the liquid flow of the first and second chemicals in the first and second supply paths A, B, and then continuing. Changes in the flow rate at the start of slurry supply. FIG. 4 shows the flow from the state where the slurry supply to the electronic device manufacturing apparatus 7 is stopped while the flow of the first and second chemicals is maintained in the first and second supply paths A and B to when the slurry supply is resumed. changes in traffic.

In the case of the comparative example in Fig. 3, the time required to reach the supply flow rate stabilization, for example, when the supply flow rate from the first supply path A is set to 200mL/min, the error from the start of re-supply to the supply flow rate The time required to shrink to ±10mL/min is about 11 seconds. This time is used to adjust the flow rate by adjusting the constant pressure valve and the orifice according to the detection values of the pressure gauge and the flowmeter after the supply restarts.

On the other hand, in the present embodiment, as shown in FIG. 4 , the flow rate is stabilized in about 2 seconds from the resumption of supply. This is because the liquid flow in the first and second supply paths A and B is maintained.

Next, a chemical solution supply device 200 according to a second embodiment of the present invention will be described with reference to FIG. 5 . The second embodiment differs 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 capable of appropriately adjusting the discharge flow rate.

With the third pump 26, in the case where the distance from the mixer 6 to the electronic device manufacturing apparatus 7 is long, the slurry can be supplied at a stable pressure with the third pump 26.

Next, a chemical solution supply device 300 according to a third embodiment of the present invention will be described with reference to FIG. 6 . The third embodiment differs from the first embodiment in that first and second cleaning valves 27 and 28 are added.

The cleaning valves 27 and 28 can clean the first supply path A. As shown in FIG. That is, the valves 8, 9, and 16 are closed, and the purge 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 . Thus, it is possible to easily clean the first supply path A for supplying the abrasive suspension which is prone to sedimentation and aggregation.

When the second cleaning valve 28 is closed and the downstream valve 9 is opened, cleaning of the mixer 6 and the electronic device manufacturing apparatus 7 can also be performed.

The washing liquid is supplied from the second washing valve 28 to the first washing valve 27, and the washing liquid flows in the direction opposite to the flow of the abrasive suspension, thereby further improving the washing effect.

Next, a medical solution supply device 400 according to a fourth embodiment of the present invention will be described with reference to FIG. 7 . In the fourth embodiment, two supply paths A1 and A2 are arranged in parallel instead of the supply path A of the first embodiment. As in the third embodiment, cleaning valves 29 to 32 are provided on the two supply paths A1 and A2.

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

The first to fourth embodiments may also be modified as follows.

When the second chemical flowing through the second supply path B is a uniform fluid such as pure water that does not settle or aggregate, the second return path E may be omitted.

When the second chemical flowing through the second supply path B is an inhomogeneous fluid that is prone to sedimentation and aggregation, a bypass path may be provided on the second supply path B.

Claims (13)

1. A chemical solution supply device that mixes first and second stock solutions stored in first and second storage tanks to generate a mixed chemical solution, and supplies the mixed chemical solution to an external device The supply device is characterized in that it comprises: first and second supply paths, the first and second raw liquids flow in the first and second supply paths respectively at prescribed flow rates; first and second flow regulating devices, which are respectively arranged on the first and second supply paths, and regulate the flow of the first and second supply paths; The first and second return paths are respectively connected at positions between the first and second flow regulating devices and the external device on the first and second supply paths, and stop flowing to the outside. When the device supplies the mixed medical solution, the first and second stock solutions are respectively returned from the first and second supply paths to the first and second storage tanks, and the flow to the external device will be stopped. The flow rates of the first and second stock solutions in the first and second supply paths are maintained at the same flow rates as when the mixed chemical solution is being supplied when the mixed chemical solution is being supplied. 2. A medical solution supply device that mixes a first liquid and a second liquid respectively stored in first and second storage tanks to form a slurry, and supplies the slurry to an external device, Features include: a first supply path in which the first liquid containing abrasive grains for preparing the slurry flows at a prescribed flow rate; a second supply path through which the second liquid mixed with the first liquid for preparing the slurry flows at a prescribed flow rate; first and second flow regulating devices, which are respectively arranged on the first and second supply paths, and are used to control the volume of the first liquid and the second liquid flowing in the first and second supply paths flow; The first and second return paths are respectively connected at positions between the first and second flow regulating devices and the external device on the first and second supply paths, and stop flowing to the outside. When the device supplies the slurry, the first liquid and the second liquid are respectively returned from the first and second supply paths to the first and second storage tanks, and the supply of the slurry to the external device is stopped. When the slurry is being supplied, the flow rates of the first liquid and the second liquid in the first and second supply paths are maintained at the same flow rates as when the slurry is being supplied to the external device. 3. The liquid medicine supply device according to claim 2, further comprising: a bypass that is parallel to the first supply path and supplies the first liquid from the first storage tank to the return path. path. 4. The liquid medicine supply device according to claim 2 or 3, wherein: an upstream valve selectively openable for introducing the associated said liquid from the associated said storage tank; a pressure adjusting device for setting the discharge pressure of each supply path; and A downstream valve selectively opened to supply the associated liquid from each supply path to the external device. 5. The liquid medicine supply device according to claim 4, further comprising: operating the upstream valve, the pressure regulating device and the flow regulating device to control the first liquid and the second liquid flow control device. 6. The liquid medicine supply device according to any one of claims 2 to 5, further comprising: a first cleaning valve for supplying cleaning liquid to the first supply path; A second purge valve that discharges the purge fluid. 7. The liquid medicine supply device according to claim 6, wherein the first supply path is one of at least two parallel supply paths; the first and second purge valves are arranged on the at least two supply paths. on the respective paths of the two supply paths. 8. The liquid medicine supply device according to claim 5, wherein said pressure adjustment means comprises: a pressure gauge for detecting the pressure in the relevant supply path and providing the detected value to said control means; and A constant pressure valve controlled by the control device according to the detection value of the pressure gauge. 9. The liquid medicine supply device according to claim 5, wherein said flow regulating means comprises: a flow meter for detecting the flow of each path and providing the detected value to said control means; An orifice controlled by the control device based on the detection value of the flowmeter. 10. A liquid supply device for supplying mixed liquid to an external device, the liquid supply device is respectively connected to a first storage tank for storing a first liquid and a second storage tank for storing a second liquid, and the first liquid and the second liquid are connected to each other. The second liquid is mixed to prepare the mixed solution; it is characterized in that it includes: a first supply path through which the first liquid flows at a prescribed flow rate; a second supply path through which the second liquid flows at a prescribed flow rate; a mixer connected to the first supply path and the second path for mixing the first liquid and the second liquid; a first shutoff valve disposed on the first supply path for selectively shutting off the supply of the first liquid to the mixer; a second shutoff valve disposed on the second supply path for selectively shutting off the supply of the second liquid to the mixer; First and second flow regulating devices, which are respectively provided at positions upstream of the first and second cut-off valves on the first and second supply paths, and are used to control the flow rates of the first liquid and the second liquid flowing in the supply path; a first return path that connects a position on the first supply path that is upstream of the first stop valve and downstream of the first flow adjustment device with the first storage tank, When the supply of the mixed liquid to the external device is stopped, the flow rate of the first liquid in the first supply path before being mixed with the second liquid is maintained to be the same as that during the supply to the external device. same flow rate; a first backflow valve, which is arranged in the middle of the first backflow path; a control device that closes the first shutoff valve and opens the first return valve when the supply of the mixed liquid to the external device is stopped, so that the first flow in the first supply path maintaining the flow rate of a liquid at the same flow rate as when it is being supplied to the external device, and returning the first liquid in the first supply path to the first storage via the first return path Can. 11. The liquid supply device according to claim 10, further comprising a second return path connecting the upstream position of the second shut-off valve and the second storage tank on the second supply path; and a second return valve provided in the middle of the second return path, the control device closes the second stop valve and opens the second stop valve when the supply of the mixed liquid to the external device is stopped. A return valve, so that the second liquid returns to the second storage tank through the second return path. 12. The liquid supply device according to claim 11, wherein when the mixed liquid is supplied to the external device, the control device opens the first and second stop valves, and closes the first stop valve. and the second return valve. 13. The liquid supply device according to claim 12, wherein the first liquid is a suspension containing abrasive particles; the second liquid is a diluent for diluting the suspension; the mixing The liquid is a slurry for grinding.

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