Waste liquid processing device and cleaning method

Abstract

To provide a waste liquid treatment device capable of producing water having a purity suitable for cleaning, and provide a cleaning method capable of obtaining a high cleaning effect.SOLUTION: A waste liquid processing device according to the present invention is a waste liquid processing device for treating a waste liquid in which particles are mixed with water, and includes: a filter unit for removing the particles from the waste liquid; a first ion exchange unit for removing anions contained as impurities in water having the first purity by bringing the water having the first purity after passing through the filter unit into contact with an ion exchange resin made of an anion exchange resin; and a second ion exchange unit that removes anions and cations contained as impurities in the water having the first purity by bringing the water having the first purity into contact with the ion exchange resin in which the anion exchange resin and a cation exchange resin are mixed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a waste liquid treatment apparatus and a cleaning method. [Background technology]

[0002] In the semiconductor device manufacturing process, a plurality of streets are set in a grid pattern on the surface of a wafer, and devices such as ICs (integrated circuits) are formed in each of a plurality of regions defined by the plurality of streets. The wafer on which the devices are formed is thinned to a predetermined thickness by, for example, grinding the back side using a grinding device, and then cut along the streets using a cutting device to separate the wafer into individual regions. This results in a plurality of semiconductor device chips, each having a device.

[0003] A cutting device used for cutting wafers includes, for example, a holding table for holding the wafer, a cutting unit having an annular cutting blade attached to one end of a spindle, and a processing fluid supply unit for supplying processing fluid to the wafer and cutting blade held on the holding table.

[0004] When cutting a wafer with a cutting device, a processing fluid is supplied to the wafer and the cutting blade by a processing fluid supply unit while the cutting blade is cutting into the wafer, thereby cooling the wafer and the cutting blade and washing away debris (processing debris) generated by the cutting process from the wafer.

[0005] The cutting machine may further include a cleaning unit for cleaning the wafer. This cleaning unit supplies a cleaning liquid to the wafer after cutting to clean the wafer, thereby washing away particles (foreign matter) such as processing debris adhering to the wafer. Waste liquid generated during the cutting and cleaning processes and containing particles such as processing debris is then discharged outside the cutting machine.

[0006] Waste liquid treatment devices that regenerate the above-mentioned waste liquid are known. For example, Patent Document 1 describes a waste liquid treatment device that includes a means for removing machining debris mixed in waste liquid discharged from a processing device such as a cutting device to produce clean water, a means for irradiating the clean water with ultraviolet light and then passing the water through an ion exchange resin to produce pure water, and a means for adjusting the pure water to a predetermined temperature. In the processing waste liquid treatment device of Patent Document 1, the pure water adjusted to the predetermined temperature is supplied to a processing liquid supply device provided in the processing device and reused. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-190128 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, in Patent Document 1, pure water generated from waste liquid is supplied to processing equipment and reused as a processing liquid and a cleaning liquid. However, cleaning using pure water alone may not be able to sufficiently remove particles adhering to wafers. Therefore, chemical liquids may be used as the processing liquid and the cleaning liquid to achieve a high cleaning effect. However, using chemical liquids raises issues such as increased costs for the chemical liquids and the hassle of managing the chemical liquids.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a waste liquid treatment apparatus capable of producing water of a purity suitable for cleaning, and a cleaning method that provides a high cleaning effect. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided a waste liquid treatment device for treating waste liquid containing particles mixed in water, the waste liquid treatment device comprising: a filter unit for removing the particles from the waste liquid; a first ion exchange unit for removing anions contained as impurities in the water of a first purity by contacting the water of a first purity after passing through the filter unit with an ion exchange resin consisting of an anion exchange resin; and a second ion exchange unit for removing anions and cations contained as impurities in the water of a first purity by contacting the water of a first purity with an ion exchange resin consisting of a mixture of anion exchange resin and cation exchange resin.

[0011] Preferably, the system includes a first pipe for guiding water of the second purity after passing through the first ion exchange unit to a processing device or a cleaning device, and a second pipe for guiding water of the third purity after passing through the second ion exchange unit to the processing device or the cleaning device.

[0012] Preferably, the system further includes a third pipe for guiding the water of the first purity to the first ion exchange unit, a fourth pipe for guiding the water of the first purity to the second ion exchange unit, and a valve unit connected to the third pipe and the fourth pipe, the valve unit being configured to be able to guide the water of the first purity to a selected one of the third pipe and the fourth pipe.

[0013] Preferably, the system further comprises a third ion exchange unit that removes cations contained as impurities in the water of the first purity by bringing the water of the first purity into contact with an ion exchange resin made of a cation exchange resin.

[0014] According to another aspect of the present invention, there is provided a cleaning method for cleaning an object to be cleaned using water of a second purity after passing through the first ion exchange unit provided in the waste liquid treatment device and water of a third purity after passing through the second ion exchange unit, the cleaning method comprising: a holding step for holding the object to be cleaned by a holding table; a first cleaning step for supplying the water of the second purity to the object to be cleaned while rotating the holding table after the holding step; and a second cleaning step for supplying the water of the third purity to the object to be cleaned while rotating the holding table after the first cleaning step.

[0015] Furthermore, according to yet another aspect of the present invention, there is provided a cleaning method for cleaning an object to be cleaned, comprising: a holding step in which the object to be cleaned is held by a holding table; a first cleaning step in which, after the holding step, alkaline water is supplied to the object to be cleaned while rotating the holding table; and a second cleaning step in which, after the first cleaning step, water of higher purity than the alkaline water is supplied to the object to be cleaned while rotating the holding table. [Effects of the Invention]

[0016] The waste liquid treatment device of the present invention can produce two types of water with different purities by removing particles from waste liquid containing particles to produce water of a first purity, and then supplying this water of the first purity to each of a first ion exchange unit and a second ion exchange unit.

[0017] Specifically, the first ion exchange unit produces alkaline water from which impurities, i.e., anions, have been removed by contacting water of a first purity with an ion exchange resin composed of an anion exchange resin, and the second ion exchange unit produces water from which impurities, i.e., anions and cations, have been removed by contacting water of a first purity with an ion exchange resin composed of a mixture of anion and cation exchange resins.

[0018] The cleaning method of the present invention, in which the object is washed with alkaline water of the second purity that has passed through the first ion exchange unit, and then washed with water of the third purity that has passed through the second ion exchange unit, provides a higher cleaning effect than a cleaning method in which the object is washed with water of the third purity only. Thus, the waste liquid treatment device of one aspect of the present invention can produce water of a purity suitable for washing the object. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing a schematic structure of a waste liquid treatment apparatus and the like. [Figure 2] FIG. 2 is a diagram showing a schematic diagram of the connection relationship between elements that constitute the waste liquid treatment device. [Figure 3] FIG. 3 is a perspective view schematically showing a part of the cutting device. [Figure 4] FIG. 4 is a perspective view schematically showing the cleaning device. [Figure 5] FIG. 5 is a flow diagram of the cleaning method. [Figure 6] FIG. 6 is a graph showing the results of measuring the size and number of particles for each of silicon wafers No. 1 to No. 4. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, an example of the configuration of a waste liquid treatment device according to this embodiment will be described. Fig. 1 is a perspective view showing a schematic structure of a waste liquid treatment device 10, etc., and Fig. 2 is a diagram showing a schematic connection relationship between elements that make up the waste liquid treatment device 10.

[0021] In Fig. 1, some components are shown as functional blocks. In Fig. 1, the X1 axis and the Y1 axis are perpendicular to each other. Furthermore, the Z1 axis and the X1 axis are perpendicular to each other, and the Z1 axis and the Y1 axis are perpendicular to each other.

[0022] The waste liquid treatment device 10 corresponds to a purification device that purifies water of a predetermined purity using a liquid (waste liquid) 4A discharged from a device (processing device 90 or cleaning device 200) that uses a liquid whose main component is water. The liquid 4A discharged from the processing device 90 or cleaning device 200 is typically water mixed with impurities such as particles, anions, cations, etc., which are typified by processing debris. Examples of the processing device 90 include cutting devices, grinding devices, polishing devices, etc. that perform predetermined processing on workpieces.

[0023] 1 and 2, the processing device 90 or the cleaning device 200 and the waste liquid treatment device 10 are connected to each other by a discharge path 2A and a supply path 2B. The discharge path 2A and the supply path 2B correspond to piping that connects the processing device 90 or the cleaning device 200 and the waste liquid treatment device 10, and are formed of tubes, pipes, etc.

[0024] 1, the waste liquid treatment device 10 includes a rectangular parallelepiped housing 12 that houses the components that make up the waste liquid treatment device 10. The housing 12 includes a bottom plate (support) 12a that supports the components of the waste liquid treatment device 10. A liquid tank (waste liquid tank) 14 that stores the liquid 4A discharged from the processing device 90 or the cleaning device 200 is provided on the bottom plate 12a.

[0025] One end of the discharge path 2A is connected to a processing device 90 or a cleaning device 200, and the other end of the discharge path 2A is connected to a liquid tank 14. Water containing impurities such as particles, anions, cations, and the like, typified by processing debris, is discharged as liquid 4A from the processing device 90 or the cleaning device 200 to the discharge path 2A. The liquid 4A discharged to the discharge path 2A is supplied to the liquid tank 14 via the discharge path 2A and stored in the liquid tank 14.

[0026] A flow path 16 is connected to the liquid tank 14. The flow path 16 is configured with piping such as tubes and pipes, and functions as a liquid supply path for supplying the liquid 4A stored in the liquid tank 14 to a filter unit 20, which will be described later. One end of the flow path 16 is connected to the liquid tank 14, and the other end of the flow path 16 is connected to the filter unit 20. Similar to the flow path 16, the other flow paths, which will be described later, are also configured with piping such as tubes and pipes. However, the configuration of each flow path is not limited to this.

[0027] In addition, a pump 18 is connected to the liquid tank 14, which sends the liquid 4A stored in the liquid tank 14 to the flow path 16. When the pump 18 is operated, the liquid 4A stored in the liquid tank 14 flows into the flow path 16. In addition, by controlling the operation of the pump 18, the flow rate of the liquid 4A flowing through the flow path 16 can be adjusted.

[0028] A pressure sensor 60 that detects the pressure of the liquid 4A flowing through the flow path 16 is connected to the flow path 16. A first valve unit 62 that controls the supply destination, flow rate, etc. of the liquid 4A flowing through the flow path 16 is also connected to the flow path 16. Specifically, the downstream side of the flow path 16 branches into two flow paths, and the first valve unit 62 has a valve 62a provided in one of the branched flow paths, flow path 16a, and a valve 62b provided in the other branched flow path 16b. The valves 62a and 62b are configured, for example, by electromagnetic valves.

[0029] 1, a pair of guide rails 22 are provided above the liquid tank 14. The pair of guide rails 22 are fixed to the housing 12 so as to be spaced apart from each other in the width direction (direction along the Y1 axis) of the waste liquid treatment device 10 and to be arranged along the length direction (direction along the X1 axis) of the waste liquid treatment device 10.

[0030] 1 and 2 is mounted on the pair of guide rails 22 so as to be slidable along the guide rails 22, i.e., along the longitudinal direction of the waste liquid treatment device 10. By moving the tray 24 along the guide rails 22, the tray 24 can be pulled out from the housing 12 or stored in the housing 12.

[0031] A filter unit 20 capable of removing particles contained in the liquid 4A supplied from the liquid tank 14 is mounted on the tray 24. The filter unit 20 has a filter 20a connected to one flow path 16a provided with a valve 62a, and a filter 20b connected to the other flow path 16b provided with a valve 62b. The liquid 4A stored in the liquid tank 14 is supplied to the filter unit 20 (filters 20a and 20b) via the flow path 16 (flow paths 16a and 16b) and the first valve unit 62 (valves 62a and 62b).

[0032] The filters 20a and 20b are typically configured by a filter equipped with a filter for filtering the liquid 4A. Specifically, the filters 20a and 20b are formed of activated carbon, zeolite, cloth, resin fiber, glass fiber, metal mesh, a reverse osmosis membrane (RO membrane), or the like. The filters 20a and 20b filter the liquid 4A to generate a liquid (filtrate, clean water) 4B from which particles of a predetermined size have been removed.

[0033] By controlling the above-described first valve unit 62, it is possible to select whether the liquid 4A is to be supplied to filter 20a or filter 20b. That is, when valve 62a is opened with valve 62b closed, the liquid 4A is supplied to filter 20a. Conversely, when valve 62b is opened with valve 62a closed, the liquid 4A is supplied to filter 20b.

[0034] As described above, the supply destination of the liquid 4A can be switched by the first valve unit 62. For example, suppose that liquid 4A continues to be supplied to filter 20a while valve 62a is open and valve 62b is closed, and as a result filter 20a becomes unusable due to reasons such as exceeding the usage limit of filter 20a. In this case, valve 62a is closed and valve 62b is opened, thereby switching the supply destination of the liquid 4A from filter 20a to filter 20b.

[0035] As a result, even if the filter 20a becomes unusable, another filter 20b can be used to continue treatment in the waste liquid treatment device 10. Although the present embodiment illustrates a structure in which two filter units 20 are provided on the tray 24, the number of filter units 20 may be one or three or more.

[0036] The liquid 4B produced by the filter unit 20 is temporarily stored in the tray 24. As shown in FIG. 1, the tray 24 is provided with an outlet (not shown) for discharging the liquid 4B, and one end of the flow path 26 is connected to the outlet of the tray 24. For example, the flow path 26 is formed of a deformable flexible tube (hose) and is supported by a plate-like support member 28 fixed to the housing 12. However, as long as the liquid 4B discharged from the outlet of the tray 24 can be made to flow into the flow path 26, there are no limitations on the structure, properties, arrangement, etc. of the flow path 26.

[0037] 1, a liquid tank (filtrate tank, clean water tank) 30 that stores liquid 4B produced by filter unit 20 is provided adjacent to liquid tank 14. The other end of flow path 26 is connected to liquid tank 30. Liquid 4B produced by filter unit 20 is temporarily stored in tray 24, and then supplied to liquid tank 30 via flow path 26 and stored in liquid tank 30.

[0038] A flow path 32 is connected to the liquid tank 30. The flow path 32 functions as a liquid supply path for supplying the liquid 4B stored in the liquid tank 30 to an ultraviolet irradiation unit 34, which will be described later. One end of the flow path 32 is connected to the liquid tank 30, and the other end is connected to the ultraviolet irradiation unit 34.

[0039] 2, a pump 64 is connected to the flow path 32, which sends the liquid 4B stored in the liquid tank 30 to the flow path 32. When the pump 64 is operated, the liquid 4B stored in the liquid tank 30 is supplied to the flow path 32. Furthermore, by controlling the operation of the pump 64, the flow rate of the liquid 4B flowing through the flow path 32 can be adjusted.

[0040] 1, a pair of guide rails 42 are provided on the sides of the liquid tank 30. The pair of guide rails 42 are fixed to the housing 12 so as to be spaced apart from each other in the width direction of the waste liquid treatment device 10 and to be arranged along the length direction of the waste liquid treatment device 10.

[0041] A rectangular tray (pan) 44 is mounted on the pair of guide rails 42 so as to be slidable along the guide rails 22, i.e., along the longitudinal direction of the waste liquid treatment device 10. By moving the tray 44 along the guide rails 22, the tray 44 can be pulled out of the housing 12 or stored in the housing 12.

[0042] An ultraviolet irradiation unit 34 is provided on the tray 44, which irradiates ultraviolet rays onto the liquid 4B supplied from the liquid tank 30. The ultraviolet irradiation unit 34 includes, for example, a pipe (not shown) through which the liquid 4B flows, and a light source (not shown) that irradiates ultraviolet rays onto the liquid 4B flowing through the pipe.

[0043] The liquid 4B stored in the liquid tank 30 is supplied to the ultraviolet irradiation unit 34 via the flow path 32. When the liquid 4B is supplied to the ultraviolet irradiation unit 34, the ultraviolet irradiation unit 34 irradiates the liquid 4B produced by the filter unit 20 with ultraviolet light. This decomposes impurities contained in the liquid 4B. For example, organic matter such as organic microorganisms remaining in the liquid 4B is decomposed by the ultraviolet light irradiation. As a result, the liquid 4B is subjected to a sterilization treatment, and liquid (water of a first purity) 4C is produced.

[0044] One end (upstream side) of the flow path 36 is connected to the ultraviolet irradiation unit 34. A second valve unit 66 is connected to the flow path 36, and controls the supply destination, flow rate, etc. of the liquid 4C flowing through the flow path 36. Specifically, the downstream side of the flow path 36 branches into two flow paths, and the second valve unit 66 has a valve 66a provided in one of the branched flow paths (third pipe) 36a and a valve 66b provided in the other branched flow path (fourth pipe) 36b. The valves 66a and 66b are configured, for example, by electromagnetic valves.

[0045] 1 and 2, a first ion exchange unit 38 and a second ion exchange unit 40 are disposed on the tray 44 at positions to the side of the ultraviolet irradiation unit 34. The upstream end of the first ion exchange unit 38 is connected to the downstream end of the flow path 36a. The upstream end of the second ion exchange unit 40 is connected to the downstream end of the flow path 36b.

[0046] Therefore, by controlling the second valve unit 66 described above, it is possible to select whether the liquid 4C is to be supplied to the first ion exchange unit 38 or the second ion exchange unit 40. That is, when the valve 66a is opened with the valve 66b closed, the liquid 4C is supplied to the first ion exchange unit 38 via the flow path 36a. Conversely, when the valve 66b is opened with the valve 66a closed, the liquid 4C is supplied to the second ion exchange unit 40 via the flow path 36b.

[0047] The first ion exchange unit 38 includes an ion exchange resin (first ion exchange resin) made of an anion exchange resin, and adsorbs anions contained in the liquid 4C to produce alkaline liquid 4D. For example, the first ion exchange unit 38 includes a cylindrical container and a first ion exchange resin filled in the container. The inside of the container is filled with a plurality of granular first ion exchange resins, with gaps forming flow paths for the liquid.

[0048] The liquid 4C entering the first ion exchange unit 38 passes through the first ion exchange resin in the container. Then, the anions contained as impurities in the liquid 4C are converted into hydroxide ions (OH - ) will be exchanged.

[0049] The second ion exchange unit 40 includes an ion exchange resin (second ion exchange resin) that is a mixture of anion exchange resin and cation exchange resin, and adsorbs anions and cations contained in the liquid 4C to produce the liquid 4E. For example, the second ion exchange unit 40 includes a cylindrical container and a second ion exchange resin filled in the container. The inside of the container is filled with a plurality of granular second ion exchange resins with gaps that serve as flow paths for the liquid.

[0050] The liquid 4C entering the second ion exchange unit 40 passes through the second ion exchange resin in the container. Then, anions contained as impurities in the liquid 4C are converted into hydroxide ions (OH - ) and the cations contained as impurities in the liquid 4C are exchanged with hydrogen ions (H + The electrical resistivity of Liquid 4E is 0.1 MΩ·cm or more, preferably 10 MΩ·cm or more.

[0051] One end (upstream side) of a flow path (first pipe) 70 is connected to the downstream end of the first ion exchange unit 38. Furthermore, one end (upstream side) of a flow path (second pipe) 72 is connected to the downstream end of the second ion exchange unit 40. In this embodiment, the other end (downstream side) of the flow path 70 and the other end (downstream side) of the flow path 72 merge to form a single flow path 46.

[0052] However, the other end of the flow path 70 and the other end of the flow path 72 do not necessarily have to merge to form the flow path 46. In the case where the other end of the flow path 70 and the other end of the flow path 72 do not merge, elements to be described later that are connected to the downstream side of the flow path 46 will be provided on the downstream side of the flow path 70 and the downstream side of the flow path 72, respectively.

[0053] 1 and 2, a precision filter 48 is provided on the tray 44 at a position to the side of the ultraviolet irradiation unit 34. The precision filter 48 has the function of filtering the liquid 4D produced by passing through the first ion exchange unit 38 and the liquid 4E produced by passing through the second ion exchange unit 40.

[0054] The downstream end of the flow path 46 is connected to the upstream end of the precision filter 48. The liquid 4D produced by the first ion exchange unit 38 and the liquid 4E produced by the second ion exchange unit 40 are supplied to the precision filter 48 via the flow paths 70, 72, 46, etc. A pressure sensor 68 is connected to the flow path 46 to detect the pressure of the liquids 4D and 4E flowing through the flow path 46.

[0055] The precision filter 48 is typically configured by a filter having a filter for filtering the liquids 4D and 4E. Specifically, like the filters 20a and 20b, the precision filter 48 is formed from activated carbon, zeolite, cloth, resin fiber, glass fiber, metal mesh, a reverse osmosis membrane (RO membrane), or the like.

[0056] The precision filter 48, for example, filters the liquid 4D to remove particles of a predetermined size, such as small pieces of ion exchange resin that flow out from the first ion exchange unit 38, to produce a liquid (water of a second purity) 4F. The precision filter 48 also filters the liquid 4E to remove particles of a predetermined size, such as small pieces of ion exchange resin that flow out from the second ion exchange unit 40, to produce a liquid (water of a third purity) 4G.

[0057] In terms of water purity, Liquid 4B is purer than Liquid 4A, Liquid 4C is purer than Liquid 4B, Liquid 4D is purer than Liquid 4C, and Liquid 4E is purer than Liquids 4C and 4D. Furthermore, Liquid 4F is purer than Liquid 4D, and Liquid 4G is purer than Liquid 4E.

[0058] It is desirable that the size of particles that can be removed by precision filter 48 be smaller than the size of particles that can be removed by filters 20a and 20b. In this case, particles such as small pieces of ion exchange resin can be removed, as well as particles such as processing debris that could not be completely removed by filters 20a and 20b.

[0059] One end (upstream side) of a flow path 50 is connected to the downstream end of the precision filter 48. The flow path 50 functions as a liquid supply path for supplying liquids 4F and 4G obtained by filtering the liquids 4D and 4E by the precision filter 48 to a temperature regulator 52, which will be described later.

[0060] A temperature regulator 52 that regulates the temperatures of the liquids 4F and 4G is provided at the upper part on the rear end side of the housing 12. The temperature regulator 52 is connected to the other end (downstream side) of the flow path 50, and the liquids 4F and 4G that flow out of the precision filter 48 are supplied to the temperature regulator 52 via the flow path 50. The temperature regulator 52 is also connected to the supply path 2B.

[0061] When liquid 4F is supplied to temperature regulator 52, temperature regulator 52 adjusts the temperature of liquid 4F to within a predetermined range and supplies it to supply path 2B. Similarly, when liquid 4G is supplied to temperature regulator 52, temperature regulator 52 adjusts the temperature of liquid 4G to within a predetermined range and supplies it to supply path 2B. Then, processing device 90 or cleaning device 200 reuses liquid 4F and liquid 4G supplied via supply path 2B as a processing liquid, cleaning liquid, etc.

[0062] A controller (control unit, control section, control device) 54 that controls the waste liquid treatment device 10 is provided at the upper part on the front end side of the housing 12. The controller 54 outputs control signals to each component of the waste liquid treatment device 10, thereby controlling the operation of each component and operating the waste liquid treatment device 10.

[0063] For example, the controller 54 is configured by a computer and includes a processing unit that executes processes such as calculations required for the operation of the waste liquid treatment device 10, and a storage unit that stores various information (data, programs, etc.) used for the operation of the waste liquid treatment device 10. The processing unit is configured by a processor such as a CPU (Central Processing Unit). The storage unit is configured by memories such as a ROM (Read Only Memory) and RAM (Random Access Memory).

[0064] In addition, a display unit (display section, output device) 56 and an input unit (input section, input device) 58 are connected to the controller 54. The display unit 56 is made up of various displays, and displays information related to the waste liquid treatment device 10. For example, the display unit 56 displays the operating status of the waste liquid treatment device 10, the liquid purification conditions, etc. In addition, the input unit 58 is made up of, for example, a plurality of operation keys, and inputs information to the controller 54 in accordance with the operation of the operator.

[0065] A touch panel may be connected to the controller 54. In this case, the touch panel functions as the display unit 56 and the input unit 58. The operator can input predetermined information to the controller 54 by performing touch operations on the touch panel while referring to the operation screen displayed on the touch panel.

[0066] 3 is a perspective view schematically showing a portion of a cutting device, which is an example of a processing device 90 that uses the liquid 4F and liquid 4G generated by the waste liquid processing device 10. In FIG. 1, the X2 axis and the Y2 axis are perpendicular to each other. Furthermore, the Z2 axis and the X2 axis are perpendicular to each other, and the Z2 axis and the Y2 axis are perpendicular to each other. As shown in FIG. 3, the processing device 90, which is a cutting device, includes a chuck table 92 that holds a wafer 11 as a workpiece to be cut.

[0067] The wafer 11 is made of a semiconductor material such as silicon and has a disk shape. That is, the wafer 11 has a disk shape having a substantially circular first surface (front surface) 11a and a substantially circular second surface (back surface) 11b opposite to the first surface 11a. A notch 11c is formed in part of the outer periphery (peripheral edge) of the wafer 11 to indicate the crystal orientation of the wafer 11.

[0068] However, the workpiece that the processing device 90 targets is not limited to the wafer 11, and the material and shape of the wafer 11 are not limited to those described above. An orientation flat may be formed on the wafer 11 instead of the notch 11c. Furthermore, the wafer 11 does not necessarily have to have the notch 11c or the orientation flat formed thereon.

[0069] A plurality of planned dividing lines (streets) 13 are set in a grid pattern on the first surface 11a of the wafer 11. Devices 15 such as ICs (Integrated Circuits) are formed in a plurality of regions separated by these planned dividing lines 13. The wafer 11 is cut along the planned dividing lines 13 by a processing device 90, which is a cutting device, to divide the wafer 11 into individual device chips, each having a device 15. However, the wafer 11 does not necessarily have to have any devices formed thereon.

[0070] The wafer 11 is supported by a frame 17 to facilitate handling during transportation, processing, and the like of the wafer 11. The frame 17 is made of a metal material such as SUS or aluminum, and is configured as an annular member having an opening 17c in the center. Specifically, the frame 17 has a substantially annular first surface 17a, a substantially annular second surface 17b opposite to the first surface 17a, and an opening 17c connected to both the first surface 17a and the second surface 17b.

[0071] A film 19 is attached to the second surface 17b of the frame 17 so as to cover the opening (hole) whose outline is defined by the opening 17c. The film 19 is, for example, a laminate including a base material and an adhesive layer (glue layer) provided on the surface of the base material. The base material is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The adhesive layer may be made of an ultraviolet-curing resin that hardens when irradiated with ultraviolet light.

[0072] However, the material, structure, etc. of the film 19 are not limited to these. For example, the film 19 may be a sheet (thermocompression sheet) that can be thermocompressed to the wafer 11 and the frame 17 and does not have an adhesive layer.

[0073] A film 19 is attached to the second surface 17b side of the frame 17. Meanwhile, in the opening defined by the opening 17c, for example, the wafer 11 is placed from the first surface 17a side of the frame 17, and the wafer 11 is fixed to the film 19. As a result, a frame unit 21 is formed in which the wafer 11, the frame 17, and the film 19 are integrated. The wafer 11 is supported by the frame 17 in this manner.

[0074] 2, the chuck table 92 has a substantially circular first surface (not shown) and a second surface (not shown) opposite the first surface. A portion of the first surface constitutes the holding surface (not shown) that holds the wafer 11 described above. The second surface side is connected to a rotational drive source (not shown) such as a motor. The rotational drive force applied from the rotational drive source causes the chuck table 92 to rotate around a rotation axis that passes through the center of the chuck table 92 and is aligned with the Z2 axis.

[0075] The processing device 90 includes a cutting unit 94. The cutting unit 94 includes a cylindrical housing 96. The housing 96 contains a cylindrical spindle (not shown) whose axis is aligned along the Y2 axis. The tip (one end) of the spindle is exposed to the outside of the housing 96, and an annular cutting blade 98 is attached to the tip of the spindle.

[0076] A rotary drive source (not shown), such as a motor, is connected to the base end (other end) of the spindle. When the rotary drive source is operated with the cutting blade 98 attached, the cutting blade 98 rotates around a rotation axis along the Y2 axis due to power transmitted from the rotary drive source via the spindle.

[0077] The cutting blade 98 may be, for example, a hub-type cutting blade (hub blade). The hub blade has an annular hub base made of a metal such as an aluminum alloy and an annular cutting edge formed along the outer periphery of the hub base. The cutting edge of the hub blade is formed by an electroformed grinding stone containing abrasive grains made of diamond, cubic boron nitride (cBN), or the like, and a binder made of nickel or the like that secures the abrasive grains. However, a washer-type cutting blade (washer blade) may also be used as the cutting blade 98. A washer blade is formed only by an annular cutting edge that contains abrasive grains and a binder made of metal, ceramics, resin, or the like that secures the abrasive grains.

[0078] With the cutting blade 98 attached to the tip of the spindle, the cutting blade 98 is covered by a blade cover 100 fixed to the housing 96. The blade cover 100 has a plurality of flow paths 102 (only some of which are shown in FIG. 2) through which the liquid 4F or 4G supplied from the waste liquid treatment device 10 flows. That is, the upstream side of the flow paths 102 is connected to the supply path 2B.

[0079] The blade cover 100 also has a pair of nozzles 104 connected to the downstream side of the flow path 102 and arranged to face the cutting blade 98 (only one of the nozzles 104 is shown in FIG. 2). Each of the pair of nozzles 104 has a predetermined length along the X2 axis, and is arranged to sandwich the lower end of the cutting blade 98 along the Y2 axis. Each of the pair of nozzles 104 is also provided with an injection port (not shown) that opens toward the cutting blade 98.

[0080] A moving unit (not shown) that moves the cutting unit 94 is connected to the cutting unit 94. The moving unit is configured, for example, by a ball screw type moving mechanism that includes a ball screw and a rotational drive source such as a motor that rotates the ball screw, and moves the cutting unit 94 along the Y2 axis and the Z2 axis. This adjusts the position of the cutting blade 98 in the directions along the Y2 axis and the Z2 axis.

[0081] The processing device 90 also includes a controller (control unit, control section, control device) 106 that controls the processing device 90. The controller 106 is connected to each component of the processing device 90 (such as a rotation drive source connected to the chuck table 92 and the cutting unit 94). The controller 106 controls the operation of the processing device 90 by outputting control signals to each component of the processing device 90.

[0082] The controller 106 is configured by, for example, a computer. Specifically, the controller 106 includes a processing unit that performs calculations and the like to operate the processing device 90, and a storage unit that stores various information (data, programs, etc.) used to operate the processing device 90. The processing unit is configured to include a processor such as a CPU (Central Processing Unit). The storage unit is configured to include memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0083] When cutting the wafer 11 using the processing device 90, the wafer 11 is first held by the chuck table 92. For example, the wafer 11 is placed on the chuck table 92 so that the first surface 11a faces upward and the second surface 11b faces the holding surface via the film 19. In this state, when a suction force (negative pressure) from a suction source is applied to the holding surface, the wafer 11 is suction-held by the chuck table 92 via the film 19.

[0084] Next, the chuck table 92 is rotated to align the length direction of the predetermined dividing line 13 with the X2 axis. Also, the position of the cutting unit 94 in the direction along the Y2 axis is adjusted so that the cutting blade 98 overlaps with an extension line of the predetermined dividing line 13. Furthermore, the height of the cutting unit 94 is adjusted so that the lower end of the cutting blade 98 is positioned below the second surface 11b of the wafer 11 (the upper surface of the film 19).

[0085] Then, while rotating the cutting blade 98, the chuck table 92 is moved along the X2 axis. As a result, the chuck table 92 and the cutting blade 98 move relatively along the X2 axis (processing feed), and the cutting blade 98 cuts into the wafer 11 along the predetermined dividing lines 13. As a result, the wafer 11 is cut and divided along the predetermined dividing lines 13.

[0086] Thereafter, by repeating the same procedure, the wafer 11 is cut along all of the planned dividing lines 13. As a result, the wafer 11 is divided into a plurality of device chips, each of which has a device 15.

[0087] During cutting of the wafer 11, a processing fluid is supplied to the wafer 11 and the cutting blade 98 from the pair of nozzles 104. Specifically, liquid F or liquid G as the processing fluid flows from the supply path 2B into the pair of nozzles 104 via a flow path 102 formed of a tube, a pipe, or the like, and is then supplied to the wafer 11 and the cutting blade 98 from the ejection ports of the nozzles 104.

[0088] In this way, by supplying the processing liquid to the wafer 11 and the cutting blade 98 while cutting the wafer 11, the wafer 11 and the cutting blade 98 are cooled, and chips (processing chips) generated by the cutting process are washed away from the wafer 11. Waste liquid (processing waste liquid) containing particles (foreign matter) such as processing chips discharged from the processing device 90 is the target of treatment by the waste liquid treatment device 10.

[0089] The processing device 90 may be a grinding device or a polishing device in addition to the above-mentioned cutting device. The grinding device has a processing unit (grinding unit) that grinds a workpiece such as a wafer 11. The grinding unit has a spindle that rotates by a rotary drive source such as a motor, and an annular grinding wheel including a plurality of grinding stones is attached to the tip of the spindle. The grinding device grinds the workpiece such as the wafer 11 by rotating the grinding wheel and bringing the grinding stones into contact with the workpiece.

[0090] In a grinding device, similar to a cutting device, liquid F or liquid G is supplied to the workpiece as a processing fluid during grinding of the workpiece. This cools the workpiece and washes away debris (processing debris) generated by the grinding process from the workpiece. When the processing device 90 is a grinding device, similar to the cutting device described above, waste liquid (processing waste liquid) containing particles (foreign matter) such as processing debris discharged from the grinding device is also subject to treatment by the waste liquid treatment device 10.

[0091] The polishing apparatus includes a processing unit (polishing unit) that polishes a workpiece such as a wafer 11. The polishing unit includes a spindle that is rotated by a rotary drive source such as a motor, and a disc-shaped polishing pad is attached to the tip of the spindle. The polishing apparatus polishes the workpiece by rotating the polishing pad and bringing it into contact with the workpiece such as a wafer 11.

[0092] During polishing using a polishing apparatus, for example, a slurry (polishing liquid) containing abrasive grains is supplied to the workpiece and polishing pad, and the workpiece is subjected to CMP (Chemical Mechanical Polishing). However, a liquid (polishing liquid) that does not contain abrasive grains may also be supplied to the workpiece and polishing pad. Even when the processing apparatus 90 is a polishing apparatus, waste liquid (processing waste liquid) containing particles (foreign matter) such as processing chips discharged from the grinding apparatus is also subject to treatment by the waste liquid treatment apparatus 10.

[0093] The cleaning apparatus 200 has a function of supplying a cleaning liquid to an object to be cleaned, such as a wafer 11, to clean the object. That is, the cleaning apparatus 200 removes particles (foreign matter) such as processing debris adhering to the surface of the object to be cleaned, using the cleaning liquid. When the cleaning apparatus 200 is connected to the waste liquid treatment apparatus 10, waste liquid (cleaning waste liquid) containing particles (foreign matter) such as processing debris discharged from the cleaning apparatus 200 is treated by the waste liquid treatment apparatus 10. The cleaning apparatus 200 may be incorporated into a processing apparatus 90 or the like.

[0094] Fig. 4 is a perspective view schematically showing the cleaning apparatus 200. For ease of explanation, some components of the cleaning apparatus 200 are omitted in Fig. 4. In Fig. 4, the X3 axis and the Y3 axis are perpendicular to each other. Furthermore, the Z3 axis and the X3 axis are perpendicular to each other, and the Z3 axis and the Y3 axis are perpendicular to each other.

[0095] 4, the cleaning device 200 includes a holding table (spinner table) 202 that can hold the above-described frame unit 21. The holding table 202 includes a disk-shaped frame body 204 made of, for example, ceramics, metal, or the like. A recess 204a that is circularly open at its upper end is formed on the upper surface of the frame body 204. A disk-shaped holding plate 206 that matches the shape of the recess 204a is fixed to the recess 204a.

[0096] The holding plate 206 is made of a porous material such as ceramics, and its upper surface (holding surface) 206a holds the second surface 11b of the wafer 11, which is the object to be cleaned, via the film 19. The upper surface 206a of the holding plate 206 is configured to be parallel to a plane along the X3 axis and the Y3 axis when the holding plate 206 is fixed in the recess 204a.

[0097] A flow path (not shown) having one end open at the bottom of the recess 204a is provided inside the frame 204. Meanwhile, a suction source (not shown) such as an ejector is connected to the other end of the flow path via a valve (not shown) or the like. Therefore, when the valve is opened, negative pressure generated by the suction source acts on the upper surface 206a of the holding plate 206 through the flow path and the recess 204a or the like.

[0098] For example, when frame unit 21 is placed on holding table 202 and film 19 attached to second surface 17b of frame 17 is in contact with upper surface 8a of holding plate 8, if negative pressure from a suction source is applied to this upper surface 206a, film 19 is sucked by upper surface 206a of holding plate 206. As a result, wafer 11 with film 19 attached thereto is held on holding table 202 with first surface 11a exposed upward.

[0099] 4, a rotation drive source 210 such as a motor is connected to the lower part of the frame 204 of the holding table 202 via a cylindrical spindle 208. Therefore, the holding table 202 rotates around a rotation axis along the Z3 axis by the power generated by the rotation drive source 210.

[0100] A plurality of air actuators 212 (three sets in this embodiment) are provided around the rotary drive source 210. When each air actuator 212 is operated, the holding table 202 moves up and down along the Z3 axis together with the rotary drive source 210, the spindle 208, etc.

[0101] A plurality of (four sets in this embodiment) holding mechanisms 214 that hold down the frame unit 21 are provided on the peripheral edge of the frame body 204 of the holding table 202. For example, the plurality of holding mechanisms 214 are arranged at approximately equal intervals along the circumferential direction of the holding table 202. The plurality of holding mechanisms 214 press down the frame unit 21 placed on the holding table 202 from above, using centrifugal force generated when the holding table 202 is rotated. When the holding table 202 is rotated at high speed, the plurality of holding mechanisms 214 presses the frame 17 against the holding table 202, and the frame unit 21 is held appropriately.

[0102] 4, a liquid supply unit (processing unit, cleaning unit) 216 is provided beside the holding table 202. The liquid supply unit 216 includes a shaft 216a erected on the outside of the holding table 202, an arm 216b extending from the upper end of the shaft 216a along the upper surface 206a of the holding plate 206, and a nozzle (liquid supply nozzle, cleaning nozzle) 216c provided at the tip of the arm 216b.

[0103] The stem 216a and the arms 216b are pipe-shaped members that have a flow path (not shown) inside them through which a liquid flows. The upstream side of the flow path of the stem 216a and the arms 216b is connected to the supply path 2B. Therefore, the liquid F or liquid G supplied from the supply path 2B flows into the nozzle 216c via the flow path of the stem 216a and the arms 216b.

[0104] The liquid supply unit 216 also includes a rotary drive source (not shown), such as a motor, that rotates the shaft portion 216a about a rotation axis along the Z3 axis. By operating the rotary drive source, the nozzle 216c can be swung above the holding table 202. By operating the liquid supply source and the rotary drive source, the nozzle 216c can be swung above the holding table 202, and liquid 4F or liquid 4G can be sprayed from the nozzle 216c toward the first surface 11a of the wafer 11 held on the holding table 202.

[0105] 4, the holding table 202 and the liquid supply unit 216 are housed in the space inside a liquid receiving container 218. This liquid receiving container 218 includes a disk-shaped bottom wall 218a and a cylindrical outer wall 218b provided along the outer periphery of the bottom wall 218a. In other words, the liquid receiving container 218 is formed in the shape of a cylinder with a bottom and a circular opening 218c at its upper end.

[0106] A circular opening (not shown) through which the spindle 208 passes is formed in the center of the disk-shaped bottom wall 218a, and a cylindrical inner peripheral wall 218d having a smaller diameter and height than the outer peripheral wall 218b is provided to surround this opening. Therefore, for example, even if the liquid sprayed from the nozzle 216c collides with the wafer 11 or the holding table 202 and scatters around, it will collect in an area on the bottom wall 218a between the cylindrical outer peripheral wall 218b and the cylindrical inner peripheral wall 218d.

[0107] The bottom wall 218a is provided with a drain port 218e that penetrates the bottom wall 218a in the thickness direction. One end of a drain hose 220 provided in the cleaning device 200 is connected to this drain port 218e. The other end of the drain hose 220 is connected to the discharge path 2A. The liquid accumulated in the liquid receiving container 218 is discharged to the outside of the cleaning device 200 through the drain port 218e and the drain hose 220, and is supplied as liquid 4A to the liquid tank 14 of the waste liquid treatment device 10 via the discharge path 2A.

[0108] A cylindrical cover 222 that surrounds the spindle 208 is provided below the holding table 202. Furthermore, legs 224 that support the liquid receiving container 218 are provided below the liquid receiving container 218. The height of the liquid receiving container 218 is adjusted to match the height of the holding table 202, etc.

[0109] A controller (not shown) is connected to the various components of the cleaning apparatus 200 described above. The operation of each component is controlled by this controller. The structure of the controller is similar to that of the controller 54 of the waste liquid treatment apparatus 10 and the controller 106 of the processing apparatus 90 described above. In other words, the functions of this controller are realized by the operation of the treatment apparatus in accordance with a program (software) stored in a storage device. However, the controller may also be realized by hardware alone.

[0110] Next, a method for cleaning the wafer 11 using the liquid F and liquid G generated by the waste liquid processing apparatus 10 will be described. Fig. 5 is a flow diagram of the cleaning method. In the cleaning method according to this embodiment, a cleaning apparatus 200 connected to the waste liquid processing apparatus 10 is used.

[0111] 5, in the cleaning method according to this embodiment, for example, a holding step S1 is performed. In the holding step S1, first, a frame unit 21 including a wafer 11, which is an object to be cleaned, is placed on a holding table 202 so that the film 19 contacts a holding surface 206a of a holding plate 206. Note that the frame unit 21 may be carried onto the holding table 202 by an operator (i.e., manually), or may be carried by a transport mechanism (not shown) or the like.

[0112] Next, the suction source is activated and the valve is opened, causing negative pressure generated by the suction source to act on the holding surface 206a of the holding plate 206 through the flow path, the recess 204a, etc. As a result, the film 19 is sucked through the holding surface 206a. That is, the frame unit 21 is held by the holding table 202 with the first surface 11a of the wafer 11 exposed upward.

[0113] After the holding step S1, a first cleaning step S2 is performed. In the first cleaning step S2, the wafer 11 is cleaned using a liquid (water of a second purity) 4F. Specifically, for example, by opening the valve 66a while the valve 66b of the waste liquid treatment device 10 is closed, the liquid 4F adjusted to a predetermined temperature by the temperature regulator 52 is supplied to the cleaning device 200 via the supply path 2B.

[0114] While the liquid 4F is being supplied to the cleaning apparatus 200, the controller of the cleaning apparatus 200 rotates the holding table 202 using the rotation drive source 210. The controller also causes the nozzle 216c to spray the liquid 4F downward from the nozzle 216c while swinging the nozzle 216c above the holding table 202. This causes the liquid F to be supplied to the first surface 11a side of the wafer 11.

[0115] Then, the liquid 4F supplied to the wafer 11 flows toward the outer periphery of the wafer 11 due to centrifugal force acting on the liquid 4F as the wafer 11 rotates. As a result, the liquid 4F flows along the first surface 11a of the wafer 11, and particles adhering to the first surface 11a of the wafer 11 are washed away. In this way, the first surface 11a of the wafer 11 is cleaned by the liquid 4F. For example, when the wafer 11 has been cleaned with the liquid 4F for a predetermined time, the controller stops spraying the liquid 4F from the nozzle 216c.

[0116] After the first cleaning step S2, a second cleaning step S3 is performed. In the second cleaning step S3, the wafer 11 is cleaned using a liquid (water of a third purity) 4G. Specifically, for example, by closing the valve 66a and opening the valve 66b of the waste liquid treatment device 10, the liquid 4G adjusted to a predetermined temperature by the temperature regulator 52 is supplied to the cleaning device 200 via the supply path 2B.

[0117] While the liquid 4G is being supplied to the cleaning apparatus 200, the controller of the cleaning apparatus 200 rotates the holding table 202 using the rotation drive source 210. The controller also causes the nozzle 216c to spray the liquid 4G downward from the nozzle 216c while swinging the nozzle 216c above the holding table 202. This causes the liquid 4G to be supplied to the first surface 11a side of the wafer 11.

[0118] Then, the liquid 4G supplied to the wafer 11 flows toward the outer periphery of the wafer 11 due to centrifugal force acting on the liquid 4G as the wafer 11 rotates. As a result, the liquid 4G flows along the first surface 11a of the wafer 11, and particles adhering to the first surface 11a of the wafer 11 are washed away. In this way, the first surface 11a of the wafer 11 is cleaned by the liquid 4G. For example, when the wafer 11 has been cleaned with the liquid 4G for a predetermined time, the controller stops spraying the liquid 4F from the nozzle 216c.

[0119] This completes the cleaning method according to this embodiment. The first cleaning step S2 and the second cleaning step S3 may be performed consecutively. For example, while the liquid 4F is being supplied to the cleaning apparatus 200 and the holding table 202 is rotating, the valves 66a and 66b of the waste liquid treatment device 10 are switched to simultaneously stop the supply of the liquid 4F to the cleaning apparatus 200 and start the supply of the liquid 4G to the cleaning apparatus 200, thereby starting the second cleaning step S3 simultaneously with the completion of the first cleaning step S2.

[0120] In the cleaning method according to this embodiment, in the first cleaning step S2, the wafer 11 is cleaned with a liquid (alkaline water of a second purity) 4F. By using the alkaline liquid 4F as the cleaning liquid, particles adhering to the surface of the wafer 11 are efficiently removed together with oil present on the surface of the wafer 11.

[0121] In the cleaning method according to this embodiment, the wafer 11 is cleaned with liquid 4G (pure water, water of a third purity) in the second cleaning step S3. This makes it possible to more reliably remove particles remaining on the surface of the wafer 11. Therefore, according to the cleaning method according to this embodiment, a higher cleaning effect can be obtained than, for example, when the wafer 11 or the like is cleaned with only pure water.

[0122] The cleaning method according to this embodiment is particularly effective when the material of the wafer 11 to be cleaned is silicon. When the material of the wafer 11 is silicon, the liquid 4A contains a large amount of SiO2 - This SiO2 - When the OH group is in contact with the anion exchange resin contained in the first ion exchange unit 38, many OH groups are - is released, and a highly alkaline (pH = 10 to 11) liquid 4F is generated. The alkaline liquid 4F is also expected to have a cleaning effect on the flow path.

[0123] An experiment was conducted to verify the cleaning effect of the cleaning method according to the present embodiment. Four silicon wafers (No. 1, No. 2, No. 3, and No. 4) were prepared as objects to be cleaned for the experiment. Each silicon wafer had a diameter of 100 mm and a thickness of 250 μm.

[0124] Silicon wafer No. 1 is a silicon wafer that has not been subjected to the cutting process or cleaning described below. Silicon wafer No. 2 is a silicon wafer that has been cut under specified conditions and then not cleaned. Silicon wafer No. 3 is a silicon wafer that has been cut under the same conditions as silicon wafer No. 2 and then cleaned with pure water. Silicon wafer No. 4 is a silicon wafer that has been cut under the same conditions as silicon wafer No. 2 and then cleaned with liquid (water of second purity) 4F and liquid (water of third purity) 4G generated by waste liquid treatment device 10 described above.

[0125] The cutting conditions for the cutting process were as follows: the feed rate of the chuck table 92 (machining feed rate, movement rate along the X2 axis) was 20 mm / s, the spindle rotation speed was 30,000 rpm, and the index feed amount (movement amount along the Y2 axis, the distance corresponding to the spacing between adjacent planned division lines 13) was 5 mm. For the pure water cleaning, a 120-second cleaning using pure water, a 90-second drying, a 120-second cleaning using pure water, and a 90-second drying were sequentially performed. The cleaning conditions for the pure water cleaning were as follows: the flow rate of the cleaning liquid (pure water) was 0.5 L / min, the rotation rate of the holding table 202 during cleaning was 800 rpm, and the rotation rate of the table during drying was 2,000 rpm. The pure water used was water of the same purity as liquid 4G.

[0126] The cleaning using Liquid 4F and Liquid 4G involved sequentially cleaning for 120 seconds with Liquid 4F, followed by drying for 90 seconds, cleaning for 120 seconds with Liquid 4G, followed by drying for 90 seconds. The other cleaning conditions were the same as those for the pure water cleaning described above.

[0127] The number of particles was measured for the silicon wafers No. 1 to No. 4 described above. An automatic wafer visual inspection system, Eagle (manufactured by Camtek), was used for the measurement. The inspection was carried out by photographing the surface of the silicon wafer and processing the obtained images.

[0128] Specifically, the brightness (pixel brightness) of a reference image acquired in advance was compared with the brightness (pixel brightness) of the image obtained by capturing an image of the silicon wafer to be inspected. In other words, among the pixels constituting the image to be inspected, areas containing pixels (dark pixels) that were significantly lower in brightness than the pixels in the reference image were extracted as areas containing particles. Furthermore, based on the number of pixels (area, size) constituting the extracted areas, the particle sizes were classified into four types: 7 μm or more but less than 10 μm, 10 μm or more but less than 20 μm, 20 μm or more but less than 30 μm, and 30 μm or more.

[0129] Fig. 6 is a graph showing the results of measuring the particle size and number for each of silicon wafers No. 1 to No. 4. Table 1 below shows the relationship between particle size and number for each of silicon wafers No. 1 to No. 4 in numerical form.

[0130] [Table 1]

[0131] As shown in Fig. 6 and Table 1, a comparison of No. 1 and No. 2 reveals that a large amount of particles are generated on the silicon wafer due to the cutting process. Furthermore, a comparison of No. 2 to No. 4 reveals that, although particles are reduced by any of the cleaning methods, No. 4, which was cleaned using both Liquid 4F and Liquid 4G, produced fewer particles than No. 3, which was cleaned using only pure water. It can be said that the cleaning method using Liquid 4F and Liquid 4G generated by the waste liquid treatment device 10 produces a higher cleaning effect than a cleaning method using only pure water.

[0132] A modified example of the waste liquid treatment device 10 of this embodiment will be described. The waste liquid treatment device 10 of this embodiment may further include a third ion exchange unit in addition to the first ion exchange unit 38 and the second ion exchange unit 40. The third ion exchange unit is disposed in parallel with the first ion exchange unit 38 and the second ion exchange unit 40, for example.

[0133] In this case, the flow path 36 is branched into another flow path in addition to the flow paths 36a and 36b. The end of this other flow path is connected to the third ion exchange unit. A valve is provided in the other flow path, similar to the flow paths 36a and 36b. Liquid 4C is supplied to the third ion exchange unit through this other flow path. The third ion exchange unit is connected to another flow path different from the other flow path described above. The other flow path is connected to the flow path 46.

[0134] The third ion exchange unit includes an ion exchange resin (third ion exchange resin) made of a cation exchange resin. The third ion exchange unit has, for example, a cylindrical container and the third ion exchange resin filled in the container. The inside of the container is filled with a plurality of granular third ion exchange resins with gaps that serve as liquid flow paths.

[0135] The liquid 4C entering the third ion exchange unit passes through the third ion exchange resin in the container. Then, the cations contained as impurities in the liquid 4C are converted into hydrogen ions (H + ) will be exchanged.

[0136] After passing through the third ion exchange unit, the liquid 4C is supplied to a precision filter 48 via a flow path 46. The precision filter 48, for example, filters the liquid generated by passing through the third ion exchange unit to remove particles of a predetermined size, such as small pieces of ion exchange resin that have flowed out of the third ion exchange unit, and generates an acidic liquid (water of a fourth purity).

[0137] In terms of water purity, water with a fourth purity is purer than Liquid 4C, and Liquid 4G is purer than water with a fourth purity. For example, by cleaning an object with water of a fourth purity and then cleaning it with Liquid 4G, it is thought that a higher cleaning effect can be obtained than when cleaning is done with pure water alone, similar to the cleaning method using Liquid 4F and Liquid 4G described above.

[0138] In addition, the structures, methods, etc. according to the above-described embodiments and modifications may be modified and implemented without departing from the scope of the present invention. [Explanation of symbols]

[0139] 11: Wafer (workpiece, cleaning item) 11a: 1st page 11b: 2nd side 11c: Notch 13: Planned division line 15: Device 17: Frame 17a: 1st page 17b: 2nd side 17c: opening 19: Film 21: Frame unit 2A: Discharge path 2B: Supply path 4A: Liquid (waste liquid) 4B: Liquid (first purity water) 4C:Liquid 4D:Liquid 4E:Liquid 4F: Liquid (second purity water) 4G: Liquid (third purity water) 10: Waste liquid treatment equipment 12: Housing 12a: Bottom plate (support part) 14: Liquid tank (waste tank) 16: Flow path 16a: Flow path 16b: Flow path 18: Pump 20: Filter unit 20a: Filter 20b: Filter 22: Guide rail 24: Saucer (bread) 26: Flow path 28: Support member 30: Liquid tank (fresh water tank) 32: Flow path 34: UV irradiation unit 36: Flow path 36a: Flow path (third pipe) 36b: Flow path (4th piping) 38: First ion exchange unit 40: Second ion exchange unit 42: Guide rail 44: Saucer (bread) 46: Flow path 48: Precision filter 50: Flow path 52: Temperature controller 54: Controller 56: Display unit 58: Input unit 60: Pressure sensor 62: First valve unit 62a: Valve 62b: Valve 64: Pump 66: Second valve unit 66a: Valve 66b: Valve 68: Pressure sensor 70: Flow path (first piping) 72: Flow path (second piping) 90: Processing equipment (cutting equipment) 92: Holding table 94: Cutting unit 96: Housing 98: Cutting blade 100: Blade cover 102: Flow path 104: Nozzle 106: Controller 200: Cleaning equipment 202: Holding table 204:Frame body 204a: recess 206: Holding plate 206a: Top surface (holding surface) 208: Spindle 210: Rotational drive source 212: Air actuator 214: Presser mechanism 216: Liquid supply unit 216a: Shaft 216b: Arm 216c: Nozzle 218: Liquid receiving container 218a: Bottom wall 218b: Outer wall 218c: opening 218d: Inner wall 218e: drainage port 220: Drain hose 222: Cover 224: Legs

Claims

1. A waste liquid treatment device for treating waste liquid containing particles mixed in water, a filter unit for removing the particles from the waste liquid; a first ion exchange unit that removes anions contained as impurities in the water of first purity by bringing the water of first purity that has passed through the filter unit into contact with an ion exchange resin made of an anion exchange resin; a second ion exchange unit that removes anions and cations contained as impurities in the water of the first purity by contacting the water of the first purity with an ion exchange resin that is a mixture of anion exchange resin and cation exchange resin.

2. a first pipe for guiding the water having the second purity after passing through the first ion exchange unit to a processing device or a cleaning device; The waste liquid treatment apparatus according to claim 1 , further comprising: a second pipe for guiding the water having the third purity after passing through the second ion exchange unit to the processing apparatus or the cleaning apparatus.

3. a third pipe for introducing the water of the first purity into the first ion exchange unit; a fourth pipe that guides the water of the first purity to the second ion exchange unit; a valve unit connected to the third pipe and the fourth pipe, The waste liquid treatment apparatus according to claim 1 or 2, wherein the valve unit is configured to be able to guide the water of the first purity to a selected one of the third pipe and the fourth pipe.

4. 3. The waste liquid treatment device according to claim 1, further comprising a third ion exchange unit that removes cations contained as impurities in the water of the first purity by contacting the water of the first purity with an ion exchange resin made of a cation exchange resin.

5. 3. A cleaning method for cleaning an object using water of a second purity after passing through the first ion exchange unit and water of a third purity after passing through the second ion exchange unit, the method comprising: a holding step of holding the object to be cleaned by a holding table; a first cleaning step of supplying the water of the second purity to the object to be cleaned while rotating the holding table after the holding step; a second cleaning step of supplying the water of the third purity to the object to be cleaned while rotating the holding table after the first cleaning step.

6. A cleaning method for cleaning an object to be cleaned, comprising: a holding step of holding the object to be cleaned by a holding table; a first cleaning step of supplying alkaline water to the object to be cleaned while rotating the holding table after the holding step; The cleaning method includes, after the first cleaning step, a second cleaning step of supplying water having a higher purity than the alkaline water to the object to be cleaned while rotating the holding table.

Images