Turbidity measuring instrument

Abstract

A turbidity measuring instrument is provided that can suitably change the resolution and measurement range of turbidity according to the turbidity of the liquid to be measured. [Solution] The turbidity measuring device comprises a wave transmitting unit that transmits measurement waves to the liquid to be measured, a wave receiving unit that detects the measurement waves transmitted from the wave transmitting unit, a movement mechanism that moves the wave transmitting unit and the wave receiving unit relatively in the direction of transmission and reception of the measurement waves, a tank in which the wave transmitting unit and the wave receiving unit are disposed and which stores the liquid to be measured, a calculation unit that calculates the turbidity of the liquid located between the wave transmitting unit and the wave receiving unit based on the measurement waves detected by the wave receiving unit, and a movement control unit that controls the relative movement of the wave transmitting unit and the wave receiving unit by the movement mechanism based on the turbidity calculated by the calculation unit.

Description

[Technical Field]

[0001] The present invention relates to a measuring instrument for measuring the turbidity of waste liquid discharged in the course of processing semiconductor wafers and the like. [Background technology]

[0002] Device chips incorporated into various electronic devices such as mobile phones and personal computers are manufactured, for example, by the following procedure: A plurality of streets (planned dividing lines) arranged in a grid pattern are defined on the surface of a semiconductor wafer substrate made of silicon or other material, and devices are formed in each of the plurality of areas defined by these streets. The substrate is then divided along the streets to obtain chips equipped with devices (device chips).

[0003] These processes are sometimes carried out while supplying water or other liquids (called cutting water, grinding water, polishing water, etc. depending on the purpose) to the object. Furthermore, before and after these processes, the object is often washed to remove processing debris and other debris adhering to the object.

[0004] In such devices for processing, cleaning, and the like, the processing liquid (waste liquid) that has been supplied to the object (hereinafter referred to as the "object to be processed") is sometimes recovered and reused as processing liquid. Since the waste liquid contains solid particles such as processing waste (sludge) generated during processing, when the waste liquid is reused, the solid particles contained in the waste liquid are removed. The removed solid particles are sometimes recovered and used separately.

[0005] Patent Document 1, for example, describes a technique for treating such waste liquid.

[0006] The handling of the waste liquid collected from the equipment may be changed depending on the amount of solid particles contained per volume. For example, as described in Patent Document 1, in the case of a processing waste liquid treatment equipment equipped with a processing debris removal unit and a pure water production device, if the turbidity of the waste liquid stored in the processing debris removal unit is relatively low, the waste liquid is sent to the pure water production device in the subsequent stage, and if the turbidity is relatively high, the waste liquid is treated in the processing debris removal unit until the turbidity is sufficiently reduced.

[0007] Turbidity can be determined using a device that uses an ultrasonic concentration meter (hereinafter referred to as a "turbidity meter" in this specification), such as that described in Patent Document 2. Note that concentration and turbidity are values ​​with different definitions, and turbidity also has multiple definitions, but they all have in common the fact that they are values ​​related to the amount of solid particles per volume contained in a liquid.

[0008] A typical ultrasonic turbidity meter measures the turbidity of a liquid by measuring the attenuation of ultrasonic waves. The turbidity meter includes a wave-transmitting unit that emits ultrasonic waves for measurement (measurement waves) and a wave-receiving unit that detects the measurement waves transmitted from the wave-transmitting unit. The measurement waves transmitted from the wave-transmitting unit are passed through the fluid to be measured and detected by the wave-receiving unit. The turbidity of the fluid through which the measurement waves have passed is calculated based on the degree of attenuation of the measurement waves.

[0009] In such turbidity meters, there is a trade-off between the resolution of turbidity measurement (the smallest detectable unit; low resolution) and the measurable range of turbidity (high upper limit of turbidity), which is determined in part by the distance between the transmitter and receiver. That is, the longer the distance between the transmitter and receiver, the higher (lower) the resolution of the measured turbidity, but the lower the upper limit of measurable turbidity. On the other hand, the shorter the distance between the transmitter and receiver, the higher the upper limit of measurable turbidity, but the lower (higher) the resolution of the measured turbidity.

[0010] This is because the degree of attenuation of the measurement wave depends on the turbidity of the fluid being measured and the distance the measurement wave travels through the fluid from the transmitting unit to the receiving unit. If the intensity of the measurement wave falls below the detection limit at the receiving unit due to attenuation, it becomes impossible to measure the turbidity. On the other hand, if the degree of attenuation is too small, the effect of measurement error on the detected degree of attenuation becomes relatively large, making it difficult to obtain a measurement value that accurately corresponds to the turbidity.

[0011] When using a turbidity meter, it is necessary to take the above into consideration and select a turbidity meter with a resolution and measurement range that suits the application and purpose.

[0012] When using a turbidimeter, there are cases where high resolution is important and cases where a wide measurement range is important for the same type of measurement object. For example, in a processing waste liquid treatment device such as that described in Patent Document 1, the waste liquid is handled differently depending on whether the turbidity of the waste liquid is low or high. Therefore, when the turbidity is low, a measurement with higher (smaller) resolution is preferable, and when the turbidity is high, a measurement with a wider measurement range (a higher upper limit of measurable turbidity) is preferable. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2022-89048 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-255307 Summary of the Invention [Problem to be solved by the invention]

[0014] An object of the present invention is to provide a turbidity measuring instrument that can suitably change the resolution and measurement range of turbidity according to the turbidity of the liquid to be measured. [Means for solving the problem]

[0015] According to one aspect of the present invention, there is provided a turbidity measuring instrument comprising: a wave transmitting unit that transmits a measurement wave to a liquid to be measured; a wave receiving unit that detects the measurement wave transmitted from the wave transmitting unit; a movement mechanism that moves the wave transmitting unit and the wave receiving unit relatively along the direction of transmission and reception of the measurement wave; a tank in which the wave transmitting unit and the wave receiving unit are disposed and which stores the liquid to be measured; a calculation unit that calculates the turbidity of the liquid located between the wave transmitting unit and the wave receiving unit based on the measurement wave detected by the wave receiving unit; and a movement control unit that controls the relative movement of the wave transmitting unit and the wave receiving unit by the movement mechanism based on the turbidity calculated by the calculation unit.

[0016] Preferably, the measurement wave is an ultrasonic wave.

[0017] Preferably, the movement control unit controls the movement mechanism so that the wave transmitting unit and the wave receiving unit are positioned at a first distance when the turbidity calculated by the calculation unit is below a predetermined first threshold, and so that the wave transmitting unit and the wave receiving unit are positioned at a second distance shorter than the first distance when the turbidity calculated by the calculation unit is above a predetermined second threshold. [Effects of the Invention]

[0018] According to one aspect of the present invention, when the turbidity of the waste liquid to be measured is relatively low, the distance between the wave-transmitting unit and the wave-receiving unit can be increased to perform measurements with relatively high resolution, while when the turbidity is relatively high, the distance between the wave-transmitting unit and the wave-receiving unit can be decreased to perform measurements with a relatively wide measurement range. In this way, the turbidity resolution and measurement range can be suitably changed depending on the turbidity of the liquid to be measured. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a system including a waste liquid treatment device. [Figure 2] FIG. 2 is a block diagram particularly showing the configuration of the waste liquid treatment device and the treatment liquid regeneration device. [Figure 3]FIG. 3 is a front view particularly showing the configuration of the turbidity measuring device in the waste liquid treatment apparatus of FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a diagram showing an example of the configuration of a system including a waste liquid treatment device to which a turbidity measuring device is applied. Fig. 2 is a block diagram particularly showing the configuration of the waste liquid treatment device and treatment liquid regeneration device. Fig. 3 is a front view showing the configuration of a turbidity measuring device 8 provided in the waste liquid treatment device.

[0021] 1, the system of this embodiment includes a grinding device 2 as a treatment device for objects to be treated, and a waste liquid treatment device 4 and a treatment liquid regeneration device 6 are connected to the grinding device 2. A turbidity measuring device 8 shown in FIG.

[0022] The workpiece 10, which is the object to be processed in the grinding device 2, is, for example, a disk-shaped wafer (semiconductor wafer) made of a semiconductor such as silicon. One side of the workpiece 10 is partitioned into a plurality of small areas by a plurality of intersecting processing lines (streets), and a device such as an IC (Integrated Circuit) is formed in each small area.

[0023] The material, shape, structure, size, etc. of the workpiece 10 are not limited to the examples described here. For example, a substrate formed using other semiconductors, ceramics, resins, metals, etc. may also be processed by the processing device (grinding device) 2.

[0024] Similarly, the type, quantity, shape, structure, size, arrangement, etc. of devices formed on the workpiece 10 are not limited to the aspects described in this embodiment, and devices may not be formed on the workpiece 10.

[0025] The grinding device 2 is a device that performs grinding processing on the workpiece 10, and includes mechanisms such as a holding mechanism 12 and a grinding mechanism 14.

[0026] The holding mechanism 12 is a mechanism for holding the workpiece 10, and is, for example, a chuck table. The upper surface of the holding mechanism 12, which is a chuck table, forms a surface along a horizontal plane, and the workpiece 10 is held by being sucked thereto. In other words, the upper surface of the holding mechanism (chuck table) 12 forms a holding surface 12a that holds the workpiece 10. The holding surface 12a is connected to a suction source (not shown) such as an ejector via a suction path (not shown) provided inside the chuck table 12.

[0027] The lower part of the chuck table 12 is connected to a rotary drive source such as a motor (not shown), and the operation of this rotary drive source causes the chuck table 12 to rotate around a rotation axis extending in the vertical direction together with the workpiece 10 held on the holding surface 12a.

[0028] In addition, a moving mechanism (not shown) is connected to the lower part of the chuck table 12. This moving mechanism (not shown) includes, for example, a ball screw arranged along the horizontal direction and a pulse motor that rotates the ball screw, and moves the chuck table 12 back and forth along the horizontal direction.

[0029] A grinding mechanism 14 is disposed above the holding mechanism (chuck table) 12. The grinding mechanism 14 includes a spindle 16 and a moving part 18 that moves the spindle 16 in the vertical direction.

[0030] The spindle 16 is a generally cylindrical member that extends along an axis that follows the vertical direction, and has a grinding wheel 20 attached to its lower end. The grinding wheel 20 is attached to the spindle 16 so that its rotation axis coincides with the axis of the generally cylindrical spindle 16, and is configured to rotate along a horizontal plane around the rotation axis by the operation of a motor or the like (not shown) provided on the spindle 16.

[0031] The grinding wheel 20 is a disk-shaped component to which multiple grinding stones 22 are attached. The multiple grinding stones 22 are arranged in an annular shape on one side of the grinding wheel 20, and the grinding wheel 20 is attached to the lower end of the spindle 16 with the side on which the grinding stones 22 are attached facing downward.

[0032] The moving unit 18 is a mechanism that moves the grinding wheel 22 and the workpiece 10 that is to be ground relatively in a direction (along the up-down direction) that intersects with the sliding surface between the grinding wheel 22 and the workpiece 10 when grinding the workpiece 10.

[0033] The moving unit 18 is configured to be able to move the spindle 16 up and down by, for example, a ball screw arranged along the vertical direction and a mechanism (not shown) with a pulse motor that rotates the ball screw. However, the mechanism by which the moving unit 18 moves the spindle 16 is not limited to this, and various mechanisms that can suitably move the spindle 16 can be adopted as the moving unit 18.

[0034] In addition, the moving unit, which is a mechanism for moving the grinding wheel 22 and the workpiece 10 relative to each other in the vertical direction, may be equipped with a mechanism for moving the workpiece 10 instead of or in addition to the mechanism (moving unit 18) for moving the grinding wheel 22 side (spindle 16) as described above.

[0035] A liquid supply unit 24, which is a nozzle for supplying water (grinding water) as a processing liquid (grinding fluid) to the chuck table 12 and the workpiece 10 held on the chuck table 12, is provided near the chuck table 12, which is the holding mechanism.

[0036] The liquid supply unit 24, which is a nozzle, is connected to a fluid supply source via a pipe through which a processing liquid (water) flows, and sprays the processing liquid supplied from the fluid supply source through the pipe onto the chuck table 12. In this embodiment, the liquid supply source is the processing liquid regeneration device 6. Note that a pure water production device or the like may be provided as the liquid supply source in addition to the processing liquid regeneration device 6.

[0037] When grinding the workpiece 10, for example, the grinding wheel 20 is first positioned above the workpiece 10 held on the chuck table 12, and the chuck table 12 and the grinding mechanism 14 are positioned so that the workpiece 10 and the grinding wheel 20 overlap in a planar view.

[0038] The chuck table 12 rotates together with the workpiece 10 about an axis extending in the vertical direction, and the spindle 16 of the grinding mechanism 14 rotates together with the grinding wheel 20 about an axis extending in the vertical direction. In this state, the spindle 16 is moved downward by the moving part 18, and the grinding wheel 20 and the workpiece 10 come relatively close to each other.

[0039] When the grinding wheel 20 and the workpiece 10 come into contact with each other while rotating, the upper surface of the workpiece 10 is ground. As grinding proceeds, the spindle 16 gradually moves downward, thereby causing the grinding of the workpiece 10 to proceed.

[0040] During grinding, a processing liquid (grinding water) is supplied from the liquid supply unit 24 to the upper surface of the workpiece 10. The supplied grinding water, together with solid particles such as machining chips generated during grinding, is guided along a flow path provided in the grinding device 2 and discharged to the outside from the discharge port 26 as waste liquid.

[0041] The discharge outlet 26 is connected to the inlet of the waste liquid treatment device 4 by a flow path such as a pipe, and the waste liquid discharged from the discharge outlet 26 is introduced into the waste liquid treatment device 4 from here.

[0042] As shown in FIG. 2, the waste liquid treatment device 4 includes a pre-treatment storage tank 28, a waste liquid treatment tank 30, and a post-treatment storage tank 32.

[0043] The pre-treatment storage tank 28 is a tank for storing waste liquid, and stores therein the waste liquid containing solid particles such as machining waste discharged from the discharge port 26 of the grinding device 2. An electrolyte introduction part 34 is connected to the pre-treatment storage tank 28.

[0044] As will be described later, the waste liquid treatment device 4 of this embodiment is configured to recover solid particles in the waste liquid by electrophoresis by applying a voltage to the waste liquid. In this case, in order for a current to flow in the waste liquid, an electrolyte acting as a charge carrier must be dissolved in the waste liquid.

[0045] The electrolyte introduction section 34 is equipped with a cylinder containing, for example, liquefied carbon dioxide gas, and is configured to blow carbon dioxide gas from the cylinder into the waste liquid stored in the pre-treatment storage tank 28. For example, carbon dioxide gas is introduced from the electrolyte introduction section 34 into the waste liquid, which is a mixture of solid particles such as silicon and water, which is the treatment liquid, and the carbon dioxide gas dissolves in the water to produce an electrolyte.

[0046] In addition, when introducing an electrolyte into the waste liquid using the electrolyte introduction section, in addition to the method of dissolving a gas such as carbon dioxide into the waste liquid as described above, it is also theoretically possible to mix a liquid such as carbonated water into the waste liquid.

[0047] As shown in Fig. 3, the pre-treatment storage tank 28, which is a tank, is provided with a turbidity measuring device 8 as a component of the pre-treatment storage tank 28. The turbidity measuring device 8 measures the turbidity of the liquid (waste liquid) stored in the pre-treatment storage tank 28 as a measurement target.

[0048] The turbidity measuring instrument 8 uses, for example, ultrasonic waves as the measurement waves. The turbidity measuring instrument 8 includes a wave transmitting unit 36 ​​that transmits ultrasonic waves as measurement waves to the liquid (waste liquid) that is the measurement target, and a wave receiving unit 38 that detects the measurement waves transmitted from the wave transmitting unit 36.

[0049] The wave transmitting section 36 and the wave receiving section 38 are disposed inside the pre-treatment storage tank 28, which is a tank, and are movable relative to each other by a movement mechanism 40.

[0050] The measurement wave (ultrasound wave) oscillator in the wave transmitting unit 36 ​​and the ultrasound detection window in the wave receiving unit 38 face each other, and the measurement wave is sent out in a direction from the wave transmitting unit 36 ​​to the wave receiving unit 38. The movement mechanism 40 is a mechanism that moves the wave transmitting unit 36 ​​and the wave receiving unit 38 relatively in the direction of transmission and reception of the measurement wave.

[0051] As the movement mechanism 40, various mechanisms can be used, such as a ball screw mechanism, a fluid pressure mechanism, or a rack and pinion mechanism, as long as they can move the wave transmitting unit 36 ​​and the wave receiving unit 38 relatively. When moving the wave transmitting unit 36 ​​and the wave receiving unit 38 relatively, only one of the wave transmitting unit 36 ​​or the wave receiving unit 38 may be moved, or both may be moved.

[0052] 2 is connected to the wave transmitting unit 36, the wave receiving unit 38, and the moving mechanism 40. The controller 42 in this embodiment is a mechanism that monitors and controls the operation of each part of the waste liquid treatment device 4, and is configured by, for example, a computer.

[0053] The computer constituting the controller 42 includes, for example, an information processing device that performs various types of information processing and a storage device that stores information. The information processing device is, for example, a CPU (Central Processing Unit). The storage device includes, for example, a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a hard disk drive or flash memory. The functions of the controller 42 are realized, for example, by the information processing device operating in accordance with a program (software) stored in the storage device.

[0054] The controller 42 particularly includes a calculation unit 42a that calculates the turbidity of the waste liquid based on the measurement wave detected in the wave receiving unit 38, and a movement control unit 42b that controls the relative movement of the wave transmitting unit 36 ​​and the wave receiving unit 38 by the movement mechanism 40.

[0055] The calculation unit 42a calculates the turbidity of the liquid (waste liquid) located between the wave-transmitting unit 36 ​​and the wave-receiving unit 38 based on the distance between the wave-transmitting unit 36 ​​and the wave-receiving unit 38 and the degree of attenuation of the measurement wave detected by the wave-receiving unit 38 (the difference or ratio between the intensity of the measurement wave sent out by the wave-transmitting unit 36 ​​and the intensity of the measurement wave detected by the wave-receiving unit 38).

[0056] The movement control unit 42b controls the relative movement of the wave transmitting unit 36 ​​and the wave receiving unit 38 based on the turbidity calculated by the calculation unit 42a, and adjusts the distance between the wave transmitting unit 36 ​​and the wave receiving unit 38.

[0057] Specifically, for example, when the turbidity calculated by the calculation unit 42a falls below a predetermined first threshold, the movement control unit 42b controls the movement mechanism 40 to position the wave transmitting unit 36 ​​and the wave receiving unit 38 at a first distance D1 (see FIG. 3). Also, when the turbidity calculated by the calculation unit 42a exceeds a predetermined second threshold, the movement control unit 42b controls the movement mechanism 40 to position the wave transmitting unit 36 ​​and the wave receiving unit 38 at a second distance D2 (see FIG. 3).

[0058] Here, the second distance D2 is shorter than the first distance D1. The first threshold and the second threshold may be the same numerical value, or, for example, the first threshold may be a numerical value lower than the second threshold.

[0059] As a result, when the turbidity of the waste liquid to be measured is relatively low, by increasing the distance between the wave-transmitting unit 36 ​​and the wave-receiving unit 38, it is possible to perform a measurement with a relatively low measurement range (a relatively low upper limit of measurable turbidity) but with a relatively high (small) resolution, while when the turbidity is relatively high, by decreasing the distance between the wave-transmitting unit 36 ​​and the wave-receiving unit 38, it is possible to perform a measurement with a relatively low (large) resolution but with a relatively wide measurement range (a high upper limit of measurable turbidity).

[0060] It should be noted that three or more distances may be set as the distance between the wave transmitting unit 36 ​​and the wave receiving unit 38 that is set according to the turbidity. Also, three or more values ​​may be set as the turbidity threshold value used when setting the distance between the wave transmitting unit 36 ​​and the wave receiving unit 38.

[0061] The waste liquid in the pre-treatment storage tank 28 is sent to the outside of the pre-treatment storage tank 28 through a liquid sending line 44. The liquid sending line 44 is, for example, a pipe through which the waste liquid flows. The downstream side of the liquid sending line 44 branches into two lines, one of which is connected to the waste liquid treatment tank 30 and the other of which is connected to the treatment liquid regeneration device 6.

[0062] A switching valve 44a, which is a three-way valve, is provided at the branched portion of the liquid supply line 44. By operating this switching valve 44a, the destination of the waste liquid discharged from the pre-treatment storage tank 28 through the liquid supply line 44 can be switched between the waste liquid treatment tank 30 and the treatment liquid regeneration device 6.

[0063] A pump is provided midway along the liquid transfer line 44, and this pump drives the flow of waste liquid from the pre-treatment storage tank 28 to the waste liquid treatment tank 30 or the treatment liquid regeneration device 6. In the system of this embodiment, pumps are provided at various locations in the lines connecting each device (the grinding device 2, the waste liquid treatment device 4, and the treatment liquid regeneration device 6) and in the lines within these devices, and the flow of waste liquid is driven by the operation of these pumps (note that not all of the pumps provided at various locations are shown in the figure, and pumps may be provided in places where no pumps are shown in the figure).

[0064] The waste liquid treatment tank 30 is a tank that stores the waste liquid sent from the pre-treatment storage tank 28. The waste liquid treatment tank 30 is provided with a recovery section 46, which is a mechanism for recovering solid particles from the stored waste liquid.

[0065] The recovery unit 46 includes an electrode plate 46a and an electrode belt 46b as electrode units, and also includes a power supply device 46c that supplies direct current to the electrode units 46a and 46b.

[0066] The electrode plate 46a is a conductive plate provided so that at least a part of it is submerged in the waste liquid stored in the waste liquid treatment tank 30, and constitutes one of the electrodes when a voltage is applied to the waste liquid from the power supply device 46c.

[0067] The electrode belt 46b is an endless belt made of a conductive material. The electrode belt 46b is wound around a plurality of rollers that are appropriately positioned relative to the waste liquid treatment tank 30, with a portion of the belt submerged in the waste liquid stored in the waste liquid treatment tank 30 and another portion positioned outside the waste liquid.

[0068] A power supply 46c is connected to the electrode plate 46a and the electrode belt 46b, which are the electrode portion.

[0069] A motor serving as a rotation drive source is connected to at least one of the rollers around which the electrode belt 46b is wound. The electrode belt 46b is fed in the longitudinal direction by the operation of the motor, so that the components of the electrode belt 46b move back and forth between the inside and outside of the waste liquid stored in the waste liquid treatment tank 30. At this time, the rollers around which the electrode belt 46b is wound that are not connected to the motor rotate in response to the electrode belt 46b, supporting the electrode belt 46b while allowing it to move along the longitudinal direction.

[0070] In a part of the area where the electrode belt 46b is arranged, outside the waste liquid stored in the waste liquid treatment tank 30, a scraper 46d is provided.

[0071] The scraper 46d is a plate-like member with one straight side formed thin, and is provided so that the thin side (cutting edge) comes into contact with the surface of the electrode belt 46b. The scraper 46d is arranged so that the direction of the cutting edge is along the width direction of the electrode belt 46b (along the surface of the electrode belt 46b and in a direction intersecting with the feeding motion of the electrode belt 46b).

[0072] In this embodiment, a pair of scrapers 46d are installed so as to sandwich the electrode belt 46b. At this position, the electrode belt 46b is sandwiched between the pair of scrapers 46d on both sides.

[0073] Below the position where the scraper 46d is provided, a collection container 46e, which is a box with an open top, is provided.

[0074] When the recovery unit 46 is in operation, the electrode belt 46b is fed by the rotation drive source of the electrode belt 46b, and a voltage is applied from the power supply 46c to the electrode plate 46a and electrode belt 46b, which are the electrode units. In this embodiment, the electrode plate 46a serves as the cathode, and the electrode belt 46b serves as the anode.

[0075] At least a portion of each of the electrode plate 46a and the electrode belt 46b is submerged in the waste liquid stored in the waste liquid treatment tank 30. Carbon dioxide gas is introduced into this waste liquid from the electrolyte introduction section 34 when the waste liquid is stored in the pre-treatment storage tank 28, generating electrolytes such as carbonate ions, bicarbonate ions, and hydrogen ions. These electrolytes act as charge carriers, causing a current to flow in the waste liquid between the electrode plate 46a and the electrode belt 46b.

[0076] The waste liquid contains processing debris generated during grinding of the workpiece 10 in the grinding device 2 (see FIG. 1). The processing debris is, for example, fine particles of single-crystal silicon. When an electric current is passed through water containing silicon particles, the silicon becomes negatively charged and adheres to the electrode belt 46b, which is the anode, by electrophoresis.

[0077] Each part of the electrode belt 46b, which is an endless belt, moves back and forth in and out of the waste liquid due to the feeding operation of the electrode belt 46b (the feeding operation of the electrode belt 46b may be performed continuously or intermittently). When silicon particles adhere to a part of the electrode belt 46b located in the waste liquid, that part eventually moves out of the waste liquid and reaches the area where the scraper 46d is provided.

[0078] The electrode belt 46b passes through the area where the scraper 46d is provided, with its surface in contact with the scraper 46d. At this time, silicon particles adhering to the surface of the electrode belt 46b are scraped off by the scraper 46d and fall into a collection container 46e below.

[0079] The component parts of the electrode belt 46b from which the silicon particles have been scraped off are again submerged in the waste liquid by the feeding operation of the electrode belt 46b, and silicon particles again adhere to these parts.

[0080] On the other hand, the silicon particles that have fallen into the collection container 46e are subjected to appropriate processing such as drying and then collected outside the apparatus (the mechanisms for drying and transporting the particles are not shown). The collected particles are reused or discarded as appropriate.

[0081] By the operation of the recovery unit 46, the solid particles in the waste liquid are recovered in this manner, and the solid particles are removed from the waste liquid stored in the waste liquid treatment tank 30, thereby purifying the waste liquid. The purified waste liquid is sent to the post-treatment storage tank 32.

[0082] The post-treatment storage tank 32 is a tank that stores the waste liquid that has been treated by the waste liquid treatment tank 30. The post-treatment waste liquid stored in the post-treatment storage tank 32 is sent to the treatment liquid regeneration device 6 through a liquid transfer line 48, which is a pipe or the like.

[0083] A cooling unit 50, such as a chiller for cooling the waste liquid, is provided in the middle of the liquid transfer line 48. The waste liquid is heated by the application of electricity in the waste liquid treatment tank 30, and the cooling unit 50 cools the heated waste liquid as necessary.

[0084] In this embodiment, the downstream side of the liquid supply line 48 branches into two, one of which merges with the liquid supply line 44 further downstream, and the other is connected to the pre-treatment storage tank 28. The waste liquid stored in the post-treatment storage tank 32 is basically sent to the treatment liquid regeneration device 6, but can also be returned to the pre-treatment storage tank 28 as necessary.

[0085] In Figure 2, the liquid supply line 48 merges with the liquid supply line 44 downstream, and when waste liquid is sent from the liquid supply line 48 to the treatment liquid regeneration device 6, the waste liquid is sent through the liquid supply line 44. However, the liquid supply line 48 may be configured as a pipe separate and independent from the liquid supply line 44.

[0086] A pump is provided midway along the liquid transfer line 48 , and this pump drives the flow of waste liquid from the post-treatment reservoir 32 to the cooling section 50 and further to the pre-treatment reservoir 28 or the treatment liquid regeneration device 6 .

[0087] The above description has been given of the functions of the controller 42, particularly the calculation of turbidity by the turbidity measuring device 8 and the movement of the wave transmitting unit 36 ​​and the wave receiving unit 38 by the moving mechanism 40, but the controller 42 may also have other functions related to the operation of the waste liquid treatment device 4. For example, the controller 42 may be configured to monitor and control the switching of the selector valves provided in the liquid sending lines 44, 48, the operation of the pumps provided in the liquid sending lines 44, 48, the on / off and output of the measurement wave in the wave sending unit 36, the operation of the electrolyte introducing unit 34, the feeding operation of the electrode belt 46b in the recovery unit 46 of the waste liquid treatment tank 30, the operation of the power supply unit 46c, the operation of the cooling unit 50, and the like (see FIG. 2).

[0088] Furthermore, for example, the same controller may control the operation of more than one of the grinding device 2, the waste liquid treatment device 4, and the treatment liquid regeneration device 6.

[0089] The controller 42 displays various information relating to the operation of the waste liquid treatment device 4, and is connected to an input / output unit 52 for inputting operations for each unit.

[0090] The input / output unit 52 is, for example, a touch panel display. An operation screen for inputting various information, commands, etc. to, for example, the turbidity measuring instrument 8 or each part of the waste liquid treatment device 4 is displayed on the input / output unit 52, and the operator can input information to the controller 42 by touching the operation screen. Note that the input / output unit 52 may be configured by separately providing a device for displaying various information and a device for inputting operations, for example, a liquid crystal display connected to the controller 42, and input devices such as a mouse and keyboard also connected to the controller 42.

[0091] The processing liquid regeneration device 6 is configured to include, for example, a pre-filtration storage tank 54 which is a tank for storing waste liquid before filtration, a first filtration section 56 equipped with a filter for filtering the waste liquid, a post-filtration storage tank 58 which is a tank for storing the waste liquid after being filtered by the first filtration section 56, an ultraviolet irradiation section 60 which irradiates the waste liquid with ultraviolet rays, and a second filtration section 62 which further filters the waste liquid.

[0092] The waste liquid sent from the waste liquid treatment device 4 is temporarily stored in the pre-filtration storage tank 54. When the waste liquid is introduced into the pre-filtration storage tank 54, the waste liquid is discharged from a shower head-shaped discharge port, and at that time, most of the carbon dioxide gas remaining dissolved in the waste liquid is released from the liquid surface.

[0093] The waste liquid stored in the pre-filtration storage tank 54 is sent to the first filtration section 56. The first filtration section 56 is equipped with a filter that filters the liquid to remove solid particles, and at least a portion of the solid particles that remain in the waste liquid in the waste liquid treatment device 4 are removed in the first filtration section 56.

[0094] The waste liquid that has passed through the first filtration unit 56 is sent to a post-filtration storage tank 58, where it is stored. The waste liquid in the post-filtration storage tank 58 is then sent to an ultraviolet irradiation unit 60. The ultraviolet irradiation unit 60 includes a tank that temporarily stores the waste liquid, and a light source such as a UV-LED that irradiates the waste liquid in the tank with ultraviolet light. If the waste liquid contains particles of organic matter or living organisms, the organic matter is decomposed by the ultraviolet light irradiated by the ultraviolet irradiation unit 60, and the waste liquid is sterilized.

[0095] The waste liquid that has passed through the ultraviolet irradiation unit 60 is sent to the second filtration unit 62. The second filtration unit 62 is equipped with an ion exchange membrane 62a and a precision filter 62b. The waste liquid sent to the second filtration unit 62 first passes through the ion exchange membrane 62a to remove electrolytes, and then is further filtered by the precision filter 62b.

[0096] The precision filter 62b is, for example, a filter with a smaller pore size than the filter provided in the first filtering section 56, and further removes finer solid particles from the waste liquid here.

[0097] The waste liquid that has passed through the second filtration section 62 is subjected to temperature adjustment such as cooling as necessary (mechanisms for temperature adjustment etc. are not shown), and is supplied again to the grinding device 2 as processing liquid (see Figure 1).

[0098] In the system of this embodiment as described above, when the turbidity of the waste liquid is low, the turbidity measuring device 8 provided in the waste liquid treatment device 4 can set the distance between the wave transmitting unit 36 ​​and the wave receiving unit 38 to a long distance (first distance D1; see FIG. 3), measure the low turbidity with high resolution, and then send the waste liquid to the treatment liquid regeneration device 6. On the other hand, when the turbidity of the waste liquid is high, the distance between the wave transmitting unit 36 ​​and the wave receiving unit 38 can be set to a short distance (second distance D2; see FIG. 3), measure the high turbidity over a wide measurement range, and then send the waste liquid to the waste liquid treatment tank 30 for treatment to remove solid particles.

[0099] That is, the turbidity measuring instrument 8 can select either the resolution or the measurement range, which are in a trade-off relationship, depending on the turbidity of the waste liquid to be measured, and perform appropriate measurements. Furthermore, the measured turbidity can be used in the subsequent treatment of the measurement target (waste liquid).

[0100] For example, if the measured turbidity is particularly high, it is possible to increase the amount of recovered solid particles by lengthening the time the waste liquid is stored in the waste liquid treatment tank 30 or by increasing the voltage applied to the waste liquid in the recovery section 46. Alternatively, if the measured turbidity is sufficiently low, it is possible to use the turbidity of the waste liquid measured with high resolution for operating the treatment liquid regeneration device 6.

[0101] Although the above description has been given of a mechanism for using ultrasonic waves as the measurement wave for the turbidity measuring device 8, the mechanism for measuring turbidity is not limited to this. For example, it is also possible to use light such as a laser beam or infrared light as the measurement wave. However, because optical measuring devices are susceptible to the influence of dirt adhering to the parts that send and receive the measurement wave, when measuring the turbidity of waste liquid as in this embodiment, a mechanism that uses ultrasonic waves as the measurement wave is more suitable.

[0102] Regarding the tank in which the turbidity measuring device 8 is provided, the case where the turbidity measuring device 8 is provided in the pre-treatment storage tank 28 of the waste liquid treatment device 4 has been described above, but the turbidity measuring device can be provided in any tank in which the liquid for which turbidity is to be measured is stored. For example, in the case of a system such as the embodiment described above, the turbidity measuring device may be provided in another tank (the waste liquid treatment tank 30, the post-treatment storage tank 32) provided in the waste liquid treatment device 4, or in the tanks (the pre-filtration storage tank 54, the post-filtration storage tank 58) of the treatment liquid regeneration device 6.

[0103] Of course, there are many other types of liquids that can be used to measure turbidity, in addition to the waste liquid generated during grinding of silicon, etc., and there are many different types and uses of devices equipped with tanks for storing liquids. Measuring devices similar to the turbidity measuring device 8 described above can also be applied to such liquids or devices.

[0104] As a treatment device for discharging turbid waste liquid, in addition to the grinding device described above, for example, a cutting device, a polishing device, a cleaning device, etc. can be envisaged.

[0105] When the processing device is a cutting device, the cutting device includes, for example, a holding mechanism for holding the workpiece, a cutting unit, and a nozzle for supplying cutting water as a processing liquid to the workpiece. The cutting unit includes a spindle that is fitted with a blade for cutting the workpiece held by the holding mechanism and rotates together with the blade, and the spindle is brought into contact with the workpiece while rotating.

[0106] When the processing device is a polishing device, the polishing device includes, for example, a holding mechanism for holding the workpiece, a polishing unit, and a nozzle for supplying polishing water as a processing liquid to the workpiece. The polishing unit includes a polishing wheel with a polishing pad attached thereto for polishing the workpiece held by the holding mechanism, and a spindle that rotates together with the polishing wheel, and the polishing pad is brought into contact with the workpiece while rotating.

[0107] When the processing device is a cleaning device, the cleaning device includes, for example, a holding mechanism for holding the object to be processed, and a nozzle for supplying cleaning water as a processing liquid to the object to be processed.

[0108] Of course, various types of processing devices other than those listed here can be envisioned as devices that perform the above-described diagnosis.

[0109] The structures, methods, etc. according to the above-described embodiments are not limited to the above-described embodiments, and may be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0110] 2: Processing device (grinding device), 4: Waste liquid processing device, 6: Processing liquid regeneration device, 8: Turbidity measuring device 10: workpiece, 12: holding mechanism (chuck table), 12a: holding surface 14: Grinding mechanism, 16: Spindle, 18: Moving part, 20: Grinding wheel 22: Grinding wheel, 24: Liquid supply nozzle, 26: Discharge port 28: Pre-treatment storage tank (tank), 30: Waste liquid treatment tank (tank) 32: Post-treatment storage tank (tank), 34: Electrolyte introduction section 36: Wave transmitter, 38: Wave receiver, 40: Movement mechanism 42: Controller, 42a: Calculation unit, 42b: Movement control unit 44: liquid transfer line, 44a: switching valve 46: Recovery unit, 46a: Electrode unit (electrode plate), 46b: Electrode unit (electrode belt) 46c: Power supply unit, 46d: Scraper, 46e: Collection container 48: Liquid transfer line, 50: Cooling unit, 52: Input / output unit 54: Pre-filtration storage tank (tank), 56: First filtration section, 58: Post-filtration storage tank (tank) 60: UV irradiation unit 62: second filtration section, 62a: ion exchange membrane, 62b: precision filter

Claims

1. a wave transmitting unit that transmits a measurement wave to the liquid that is the measurement target; a wave receiving unit that detects the measurement wave sent from the wave transmitting unit; a moving mechanism that moves the wave transmitting unit and the wave receiving unit relatively along the direction of transmission and reception of the measurement wave; a tank in which the wave transmitting unit and the wave receiving unit are disposed and which stores a liquid to be measured; a calculation unit that calculates the turbidity of a liquid located between the wave transmitting unit and the wave receiving unit based on the measurement wave detected by the wave receiving unit; a movement control unit that controls the relative movement of the wave transmitting unit and the wave receiving unit by the movement mechanism based on the turbidity calculated by the calculation unit; A turbidity measuring instrument equipped with

2. 2. The turbidity meter according to claim 1, wherein the measuring wave is an ultrasonic wave.

3. The movement control unit When the turbidity calculated by the calculation unit is lower than a predetermined first threshold, the wave transmitting unit and the wave receiving unit are positioned at a first distance from each other; A turbidity measuring instrument as described in claim 1 or claim 2, which controls the moving mechanism so that the transmitting unit and the receiving unit are positioned at a second distance shorter than the first distance when the turbidity calculated by the calculation unit exceeds a predetermined second threshold value.

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