Cleaning method

Abstract

The present invention provides a cleaning method that allows for cleaning with sufficient cleaning power, without excess or deficiency, when supplying fluid to the holding surface of a holding table or the object held on the holding surface for cleaning. [Solution] A cleaning method for cleaning an object to be cleaned, which includes at least one of a holding surface (282) of a holding table (28) and an object to be cleaned (90) held on the holding table (282), comprising: a fluid supply step (S20) of supplying two fluids (T) in the direction toward the holding surface (282); a measurement step (S30) of measuring the external force applied to the holding surface (282) in the fluid supply step; an adjustment step (S40) of setting the supply amount of the two fluids (T) so that the external force falls within a predetermined range; and a cleaning step (S50) of cleaning the object to be cleaned with the supply amount set in the adjustment step.

Description

Technical Field

[0001] The present invention relates to a cleaning method.

Background Art

[0002] A method of supplying a fluid to a holding surface of a holding table or an object held on the holding surface for cleaning is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the cleaning method described in Patent Document 1, there is no specific mention of a method for quantitatively measuring and adjusting the cleaning power in order to clean with sufficient cleaning power without excess or deficiency.

[0005] The present invention has been made in view of this point, and an object thereof is to provide a cleaning method capable of cleaning with sufficient cleaning power without excess or deficiency when supplying a fluid to a holding surface of a holding table or an object held on the holding surface for cleaning.

Means for Solving the Problems

[0006] A cleaning method according to one aspect of the present invention is a cleaning method for cleaning a cleaning object including at least one of a holding surface of a holding table and an object held on the holding table. The cleaning method includes a fluid supply step of supplying a fluid in a direction toward the holding surface, a measurement step of measuring an external force applied to the holding surface in the fluid supply step, an adjustment step of setting a supply amount of the fluid so that the external force becomes a value within a predetermined range, and a cleaning step of cleaning the cleaning object with the supply amount set in the adjustment step. [Effects of the Invention]

[0007] According to the present invention, in a cleaning method that involves supplying fluid to the holding surface of a holding table and the object held on the holding surface for cleaning, it is possible to clean with sufficient cleaning power without excess or deficiency. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a grinding apparatus equipped with a cleaning device according to this embodiment. [Figure 2] This is a schematic diagram illustrating a specific example of a washing unit and a holding table. [Figure 3] This is a schematic diagram illustrating an example of load sensor placement. [Figure 4] This is a flowchart illustrating the procedure of the cleaning method according to this embodiment. [Figure 5] Figure 4 is a flowchart illustrating the detailed steps of the measurement process. [Figure 6] Figure 5 is a flowchart illustrating the detailed steps of the determination process. [Figure 7] Figure 4 is a flowchart illustrating the detailed steps of the cleaning process. [Modes for carrying out the invention]

[0009] Embodiments will be described below with reference to the drawings. Figure 1 is a perspective view of a grinding apparatus equipped with a cleaning device according to this embodiment. The grinding apparatus 2 shown in Figure 1 is a device that grinds a workpiece 90 (which becomes a cleaned workpiece 90 after grinding) held on a holding table 28 using a grinding mechanism 23. The front (-Y direction side) of the base 20 of the grinding apparatus 2 is an loading / unloading area where the workpiece 90 is loaded and unloaded from the holding table 28, and the rear (+Y direction side) of the base 20 is a processing area where the grinding of the workpiece 90 held on the holding table 28 is performed by the grinding mechanism 23. The grinding apparatus 2 is equipped with a cleaning device 1 according to the present invention (hereinafter referred to as the cleaning device 1 of this embodiment). The grinding apparatus 2 may also be a two-axis or more grinding apparatus equipped with a rough grinding mechanism and a finish grinding mechanism, and capable of positioning the workpiece 90 below the rough grinding mechanism or the finish grinding mechanism using a rotating turntable.

[0010] The workpiece 90 is, for example, a circular semiconductor wafer made of a silicon base material. In Figure 1, the surface 900 (hereinafter referred to as the bottom surface 900) of the workpiece 90, which is facing downwards, has multiple devices formed on it and is protected by protective tape (not shown). The back surface 903 (hereinafter referred to as the top surface 903) of the workpiece 90, which is facing upwards, is the workpiece surface that will be ground.

[0011] The holding table 28, shown in Figure 1 and having a circular shape in plan view, comprises, for example, a circular plate-shaped porous member 280 and a frame 281 that supports the porous member 280. The porous member 280 is in communication with a suction source 289, such as an ejector mechanism or a vacuum generator, and the suction force generated by the suction source is transmitted to the holding surface 282, which is the upper surface of the porous member 280, so that the holding table 28 can hold the workpiece 90 by suction on the holding surface 282. The holding surface 282 of the porous member 280 and the upper surface 283 of the frame 281 are flush and at the same height.

[0012] As shown in Figure 1, the holding table 28 is surrounded by a cover 284 and is rotatable by a rotation mechanism 29 around a rotation axis whose axis direction is the Z-axis direction (vertical direction) and which passes through the center of the holding surface 282. It is also capable of reciprocating on the base 20 in the Y-axis direction by a Y-axis feed unit (not shown), such as an electric slider, which is located below the cover 284 and a bellows cover 287 connected to the cover 284 and which expands and contracts in the Y-axis direction.

[0013] A column 21 is erected on the rear side of the base 20, and a grinding feed unit 24 is provided on the front side of the column 21 on the -Y side, which moves the grinding mechanism 23 closer to and further away from the holding surface 282 of the holding table 28 in the vertical direction (Z axis direction).

[0014] The grinding feed unit 24 consists of a ball screw 240 whose axis is the Z-axis direction, a pair of guide rails 241 extending parallel to the ball screw 240, a motor 242 connected to the ball screw 240 and rotating the ball screw 240, and a lifting plate 243 whose internal nut is screwed onto the ball screw 240 and whose side slides against the pair of guide rails 241. As the motor 242 rotates the ball screw 240, the lifting plate 243 is guided by the guide rails 241 and moves in the Z-axis direction, and the grinding mechanism 23 attached to the lifting plate 243 also moves in the Z-axis direction.

[0015] The grinding mechanism 23, which grinds the workpiece 90 held by the holding surface 282 of the holding table 28, comprises a rotating shaft 230 whose axial direction is the Z-axis direction, a housing 231 that rotatably supports the rotating shaft 230 by an air bearing or the like formed inside, a motor 232 that rotationally drives the rotating shaft 230, a disc-shaped mount 233 connected to the lower end of the rotating shaft 230, a grinding wheel 234 that is detachably mounted on the lower surface of the mount 233, and a holder 235 that supports the housing 231 and is connected to the lifting plate 243.

[0016] The grinding wheel 234 includes a wheel base 236 and a plurality of segment grinding wheels having a substantially rectangular parallelepiped shape that are annularly arranged on the bottom surface of the wheel base 236. The segment grinding wheels are formed by fixing diamond abrasive grains or the like with, for example, a resin bond or a vitrified bond. And an annular grinding wheel 237 is formed by a plurality of annularly arranged segment grinding wheels. Note that a grinding wheel in which the segment grinding wheels are arranged in a continuous annular shape without gaps, that is, a so-called continuously arranged grinding wheel, may be arranged on the lower surface of the wheel base 236.

[0017] Inside the rotating shaft 230, a flow path (not shown) that communicates with a grinding water supply source and serves as a path for grinding water is provided so as to penetrate in the axial direction of the rotating shaft 230. The flow path (not shown) further passes through the mount 233 and opens on the bottom surface of the wheel base 236 so as to be able to eject grinding water toward the annular grinding wheel 237.

[0018] The cleaning device 1 according to the present embodiment includes a holding table 28 that holds the object to be cleaned 90 on the holding surface 282 and a cleaning unit 113. The cleaning unit 113 includes a nozzle 10 that injects a two-fluid mixture of a liquid (for example, water) and a gas (for example, air) toward the holding surface 282.

[0019] FIG. 2 is a schematic diagram specifically explaining an example of the cleaning unit and the holding table. A rectangular opening (not shown) is formed on the lower surface of the cleaning unit 113, and the movement path of the holding table 28 is located below the opening. The cleaning unit 113 includes, in addition to the nozzle 10, a liquid flow rate adjustment unit 102, a gas flow rate adjustment unit 103, a mixing unit 104, and a flow rate setting unit 105. The nozzle 10 is, for example, a slit nozzle, extends in the X-axis direction with a length of at least the radius of the holding surface 282 or more, and a slit-shaped injection port 100 is formed on its lower surface, and the two-fluid T can be injected in a band shape.

[0020] The cleaning unit 113 communicates with a liquid supply source 108 that can send out, for example, pure water as a cleaning liquid through joints and pipes such as resin tubes. Further, the cleaning unit 113 communicates with a gas supply source 109 that can send out, for example, compressed air as a cleaning gas through joints and pipes such as resin tubes. The liquid supplied from the liquid supply source 108 is adjusted in flow rate by the liquid flow rate adjustment unit 102 and then supplied to the mixing unit 104. Also, the gas supplied from the gas supply source 109 is adjusted in flow rate by the gas flow rate adjustment unit 103 and then supplied to the mixing unit 104. In the mixing unit 104, the liquid and the gas are mixed to form a two-fluid T. The two-fluid T is supplied from the mixing unit 104 to the nozzle 10 and is sprayed in a band shape from the injection port 100 of the nozzle 10 toward the holding surface 282.

[0021] Note that the nozzle 10 is not limited to the slit nozzle as described above. For example, a plurality of nozzles may be arranged in the cleaning unit 113 at equal intervals within the radius from the center to the outer peripheral edge of the holding surface 282. In this case, the nozzle has, for example, a linear outer shape extending in the Z-axis direction, and a flat pattern nozzle that can obtain a fan-shaped spread pattern in which the two-fluid sprayed from the injection port formed at the lower end thereof spreads in a fan shape, or a full cone pattern nozzle that can obtain a conical injection pattern may be used. Also, the plurality of nozzles may be arranged offset in the circumferential direction of the holding surface 282, and the two-fluid sprayed from each nozzle may clean an annular region near the center of the relatively rotating holding surface 282, an annular region in the middle of the holding surface 282, and an annular region on the outer peripheral side of the holding surface 282.

[0022] Also, the liquid supplied from the liquid supply source 108 is not limited to pure water, and other liquids such as a mixed liquid of a surfactant and pure water may be used. Also, the gas supplied from the gas supply source 109 is not limited to air, and other gases such as CO2 (carbon dioxide) may be used.

[0023] The holding table 28 comprises a porous member 280, a frame 281 that supports the porous member 280, and a load sensor 285 that serves as an external force measuring sensor. The porous member 280 is in communication with a suction source 289, such as an ejector mechanism or a vacuum generator, and the suction force generated by the suction source is transmitted to the holding surface 282, which is the upper surface of the porous member 280, allowing the holding table 28 to hold the workpiece 90 by suction on the holding surface 282. The holding surface 282 of the porous member 280 and the upper surface 283 of the frame 281 are flush and at the same height.

[0024] The load sensor 285 measures the load in a direction perpendicular to the holding surface 282 of the holding table 28 (the Z-axis direction). That is, the load sensor 285 measures the external force applied to the holding surface 282 (or the workpiece 90 held on the holding surface 282) by the two fluids T sprayed from the nozzle 10. The load sensor 285 can also measure the external force applied to the workpiece 90 when cutting or polishing is performed. The load sensor 285 is placed, for example, on the lower surface 286 of the frame 281, that is, on the surface opposite to the holding surface 282. However, the position in which the load sensor 285 is installed is not limited to this, and it may be embedded in the frame 281, for example.

[0025] Figure 3 is a schematic diagram illustrating an example of load sensor arrangement. Figure 3 shows the positional relationship between the holding surface 282 and the load sensors 285 as viewed from the +Z direction. As an example, Figure 3 shows a case where three load sensors 285 are arranged. The load sensors 285 are arranged so as to overlap with the holding surface 282 when viewed from the +Z direction, and are, for example, arranged at equal intervals on concentric circles from the center of the holding surface 282. Note that the number and position of the load sensors 285 are not limited to the example shown in Figure 3. There may be two or fewer, or four or more. Also, the load sensors 285 do not have to be arranged at equal intervals.

[0026] The load sensor 285 is electrically connected to the flow rate setting unit 105. The flow rate setting unit 105 receives the measured value from the load sensor 285. The flow rate setting unit 105 sets the flow rate of the liquid and the gas to be supplied to the mixing unit 104 according to the input measured value. The liquid flow rate set in the flow rate setting unit 105 is input to the liquid flow rate adjustment unit 102. The gas flow rate set in the flow rate setting unit 105 is input to the gas flow rate adjustment unit 103. The liquid flow rate adjustment unit 102 adjusts the flow rate of the liquid supplied from the liquid supply source 108 according to the flow rate input from the flow rate setting unit 105. The gas flow rate adjustment unit 103 adjusts the flow rate of the gas supplied from the gas supply source 109 according to the flow rate input from the flow rate setting unit 105.

[0027] Furthermore, the cleaning device 1 includes a rotation mechanism 29 that rotates the holding table 28 around the center of the holding surface 282, a lifting mechanism 11 that moves the cleaning unit 113 perpendicular to the holding surface 282 (in the Z-axis direction), and a positioning unit 12.

[0028] The lifting mechanism 11 is, for example, located on the front of a gantry-shaped column (not shown) erected on the base 20 so as to straddle the movement path of the holding table 28 in the X-axis direction. It is an air cylinder or electric cylinder, etc., that raises and lowers a rod 111 extending in the Z-axis direction from the cylinder case 110 in the Z-axis direction, and a cleaning unit 113 is connected to the lower end of the rod 111. The positioning unit 12 positions the nozzle 10 at an appropriate height relative to the holding surface 282 when the cleaning unit 113 is lowered by the lifting mechanism 11.

[0029] The positioning unit 12 is a roller 12 connected to the nozzle 10 and in contact with the holding surface 282 or the upper surface 283 of the frame 281 (in this embodiment, the upper surface is at the same height as the holding surface 282 and is arranged in an annular shape relative to the holding surface 282). The roller 12 is rotatably supported, for example, on the outer surface of the cleaning unit 113 via a pivot shaft. The lower portion of the roller 12 protrudes a predetermined distance below the lower surface of the cleaning unit 113. The roller 12 may also be directly connected to the side surface of the nozzle 10 within the cleaning unit 113.

[0030] The operation of the cleaning apparatus 1, configured as described above, will be explained using Figures 4 to 7. Figure 4 is a flowchart illustrating the procedure of the cleaning method according to this embodiment. Figure 5 is a flowchart illustrating the detailed procedure of the measurement step shown in Figure 4. Figure 6 is a flowchart illustrating the detailed procedure of the determination step shown in Figure 5. Figure 7 is a flowchart illustrating the detailed procedure of the cleaning step shown in Figure 4. The cleaning method according to this embodiment includes six steps, as shown in Figure 4. Each step will be described in detail below.

[0031] First, in the preliminary preparation step (S10), the object to be cleaned is prepared and setting values ​​are registered. If the object to be cleaned is the object to be cleaned 90, the object to be cleaned 90 is placed on the holding surface 282 of the holding table 28 with their centers roughly aligned. The suction force generated by the suction source 289 is transmitted to the holding surface 282, and the holding table 28 holds the object to be cleaned 90 by suction on the holding surface 282. On the other hand, if the object to be cleaned is the holding surface 282 of the holding table 28, the object to be cleaned 90 is not placed on it, and the holding surface 282 is left exposed. Then, the holding table 28 is positioned below the Z-axis of the nozzle 10.

[0032] In the preparation step, settings for adjusting the flow rate of liquids or gases are registered. For example, the allowable range of external force (measured by the load sensor 285) is registered in the flow rate setting unit 105. The greater the external force, the greater the cleaning force, and the smaller the external force, the less the cleaning force. Therefore, the allowable range of the setting value corresponding to the desired cleaning force is registered. It is preferable to set both an upper and lower limit for the allowable range, but a lower limit alone is also acceptable. Alternatively, a specific value may be set instead of a range.

[0033] The setting values ​​may be registered after each wash, or they may be registered at predetermined intervals rather than every time. For example, they may be registered each time the usage period (number of uses) of the retention table 28 reaches a set period (number of uses). Also, when executing the judgment step (S32) described later, both the reference range and the judgment width of the measured values ​​are registered in the preparation step.

[0034] Next, in the fluid supply step (S20), the supply of liquid from the liquid supply source 108 to the mixing unit 104 is started, and the supply of liquid from the gas supply source 109 to the mixing unit 104 is started. In the mixing unit 104, the liquid and gas are mixed to form two fluids T, and the two fluids T are sprayed in a band shape from the nozzle 100 of the nozzle 10 toward the holding surface 282.

[0035] In the subsequent measurement step (S30), the external force applied to the holding surface 282 by the injection of the two fluids T is measured by the load sensor 285. As shown in Figure 5, the measurement step includes two steps. First, the measurement value from the load sensor 285 is obtained (S31). The measurement value is input to the flow rate setting unit 105 without delay. Next, in the determination step (S32), it is determined whether there is an abnormality in the nozzle 10 based on the measurement value. Note that the determination step is often performed during maintenance and inspection, and can be omitted in normal cleaning operations. If the determination step is not performed, the measurement step in Figure 5 is terminated.

[0036] As shown in Figure 6, in the determination step, it is first determined whether the measured value exceeds the reference range by a predetermined value (determination range) or more (S321). Here, the reference range and the determination range are set values ​​registered in the preparation step. The reference range is the range of values ​​that can be measured by the load sensor 285 when there is no abnormality in the nozzle 10 and the cleaning operation is performed normally. For example, the range of the measured value of the load sensor 285 in the previous cleaning is set as the reference range. If the nozzle 10 is new and is being used for cleaning for the first time, for example, the first measured value is set. The determination range is the range within which the cleaning operation is allowed to continue even if it exceeds the upper limit or lower limit of the reference range. If the measured value exceeds the reference range by a predetermined value or more (S321, YES), it is determined that an abnormality has occurred in the nozzle 10 or the load sensor 285, and the abnormality is notified (S322), and the determination step ends. On the other hand, if the measured value does not exceed the reference range by a predetermined value (S321, NO), it is determined that there is no abnormality in the nozzle 10 or the load sensor 285, and the determination step is terminated.

[0037] It should be noted that the determination in S321 alone does not make it possible to determine whether the abnormality is in the nozzle 10 or the load sensor 285. Therefore, the location of the abnormality may be estimated by comparing it with other measured values. For example, if the load sensor 285 is also used to measure the external force during grinding in the grinding apparatus 2, and no abnormalities are observed in the measured values ​​during grinding, then it can be estimated that the abnormality is in the nozzle 10.

[0038] Returning to Figure 4, the next step after the measurement step is the adjustment step (S40). In the adjustment step, the amount of fluid supplied is set so that the measured value input to the flow rate setting unit 105 falls within an acceptable range. Specifically, the flow rate setting unit 105 sets the flow rate of the liquid and the gas to be supplied to the mixing unit 104 according to the measured value input from the load sensor 285.

[0039] The external force applied to the holding surface 282 by the two fluids T is proportional to the flow rates of the two fluids T. Therefore, if the measured value falls below the lower limit of the allowable range, the flow rates of the liquid and gas are increased. Also, an upper limit of the allowable range is set, and if the measured value exceeds this upper limit, the flow rates of the liquid and gas are decreased. It is preferable to change the flow rates of the liquid and gas so as not to change the ratio of the flow rates of the liquid and gas, but it is also acceptable to adjust only the flow rate of one of them.

[0040] The cleaning force increases as the external force applied to the holding surface 282 by the two fluids T increases, and decreases as the external force decreases. In other words, in the cleaning method of this embodiment, if the external force falls below the lower limit, the flow rate setting unit 105 automatically adjusts to increase the flow rate of the two fluids T, thereby preventing insufficient cleaning force. Also, if an upper limit is set for the external force, if it exceeds this limit, the flow rate setting unit 105 automatically adjusts to decrease the flow rate of the two fluids T, thereby preventing excessive cleaning force. Furthermore, the consumption of the two fluids T can be suppressed, thereby reducing costs.

[0041] Finally, in the cleaning step (S50), the object to be cleaned 90 (or the holding surface 282) is cleaned. The specific procedure of the cleaning step will be explained using Figure 7. First, the cleaning of the object to be cleaned 90 (or the holding surface 282) is started by spraying two fluids T from the nozzle 10 at the flow rate set in the adjustment step (S51). In the cleaning method of this embodiment, the fluid flow rate may be adjusted not only before cleaning but also during cleaning while monitoring the measured value of the load sensor 285. If the fluid flow rate is adjusted during cleaning, that is, if the measured value of the load sensor 285 is monitored (S52, YES), the measurement step (S30) and adjustment step (S40) described above are performed. The measurement step and adjustment step may be performed regularly at regular time intervals or continuously.

[0042] The measurement step and adjustment step may be repeated while cleaning is being performed. That is, if cleaning is to be continued after the adjustment step (S53, YES), the process returns to the measurement step. On the other hand, if cleaning is not to be continued (S53, NO), the cleaning is stopped (S54). That is, the injection of the two fluids T from the nozzle 10 toward the holding surface 282 is stopped, and the cleaning step shown in Figure 7 is terminated. The process returns to Figure 4, and with the completion of the cleaning step, the cleaning method of this embodiment is terminated. Note that the measurement step and adjustment step may be performed once before cleaning, and if it is determined that there is no abnormality, the process may be continued with the flow rate adjusted in the adjustment step without being repeated while cleaning is being performed.

[0043] As described above, according to this embodiment, when cleaning an object to be cleaned by spraying two fluids T, the external force applied to the holding surface 282 is measured using the load sensor 285. The flow rate setting unit 105 adjusts the flow rate of the two fluids T so that the measured value falls within a predetermined range (tolerance range). In this way, since cleaning is performed with two fluids T whose flow rate is appropriately adjusted, sufficient cleaning power without excess or deficiency can be obtained. In other words, in a cleaning method that supplies fluid to the holding surface 282 of the holding table 28 and the object to be cleaned 90 held on the holding surface 282 to clean, cleaning can be performed with sufficient cleaning power without excess or deficiency.

[0044] Furthermore, according to this embodiment, if the value of the load sensor 285 changes by more than a predetermined value (judgment range) from the set reference range, it is possible to determine that there is an abnormality. Therefore, deterioration of the nozzle 10 over time can be detected.

[0045] In the above description, we explained the case in which a two-fluid mixture T of liquid and gas is injected from the nozzle 10 toward the holding surface 282, but the injected fluids are not limited to two fluids. For example, the cleaning method of this embodiment can be applied when injecting either a liquid such as high-pressure water or a gas such as CO2, or when injecting a mixed fluid of two or more fluids, such as a three-fluid mixture of two types of liquids and one type of gas.

[0046] Furthermore, the holding table 28 of this embodiment is not limited to a configuration provided in a grinding machine, but may also be a holding table provided in a cutting machine that processes an object with a cutting blade, a laser beam irradiation machine, a cutting machine that processes an object with a cutting tool, a plasma processing machine, a cleaning machine that cleans an object, an imaging machine, an inspection machine, a transport machine, a film deposition machine, a protective member attachment machine that attaches a protective member to an object, a peeling machine that peels a protective member from an object, a transport machine that transports an object from one cassette to another or other storage unit, a storage machine that stores an object, and so on. Furthermore, this embodiment is not limited to cleaning the holding table 28 itself; it is also possible to similarly measure and investigate whether the flow rate is appropriate by spraying the fluid used in the processing steps of the object to be processed toward the holding surface 282 of the holding table 28 using a load sensor. For example, it can also be applied to adjusting the flow rate of the processing fluid supplied from the processing fluid supply unit to the processing point or to the processing tool during processing.

[0047] While several embodiments of the present invention have been described, these embodiments are provided as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Industrial applicability]

[0048] As described above, the cleaning method of the present invention can clean with sufficient cleaning power without excess or deficiency, and is useful when supplying fluid to the holding surface of a holding table or the object held on the holding surface for cleaning. [Explanation of Symbols]

[0049] 1. Washing device 2. Grinding device 10 nozzles 11. Lifting mechanism 12 Positioning part (roller) 20 base 21 Columns 23 Grinding mechanism 24. Cutting feed unit 28 Retention Table 29 Rotation mechanism 90 Workpiece (object to be cleaned) 100 injection port 102 Liquid flow rate adjustment section 103 Gas flow rate adjustment section 104 Mixing section 105 Flow rate setting section 108 Liquid Source 109 Gas supply source 110 Cylinder Case 111 Rod 113 Washing Unit 230 Rotation axis 231 Housing 232 Motor 233 Mount 234 Grinding Wheel 235 Holder 236 Wheel base 237 Grinding Wheel 240 Ball Screw 241 Guide Rail 242 Motor 243 Lifting platform 280 Porous material 281 Frame 282 Holding surface 283 Top surface 284 Cover 285 Load Sensor 286 Bottom surface 287 Bellows cover 289 Suction source 900 Surface (bottom surface) 903 Back side (top side) T Two-fluid

Claims

1. The cleaning object includes at least one of the holding surface of a holding table and the object held by the holding table. A cleaning method, A fluid supply step of supplying fluid in the direction toward the holding surface, In the fluid supply step A measurement step for measuring the external force applied to the holding surface, So that the external force falls within a predetermined range An adjustment step to set the supply amount of the fluid, With the supply amount set in the adjustment step, A cleaning step for cleaning the object to be cleaned, A cleaning method comprising the following features.

2. The measurement step is, The load is measured by a load sensor located inside the holding table or on the opposite side of the holding surface of the holding table. The cleaning method according to feature 1.

3. In the measurement step, which is performed with the flow rate of the fluid set to a first value, If the value of the external force being measured changes by more than a predetermined value from a preset reference range, Determination step for determining an abnormality The cleaning method according to claim 1, further comprising:

4. The fluid is a two-fluid mixture of gas and liquid. The adjustment step involves adjusting the flow rate of at least one of the gas and the liquid. The cleaning method described in claim 1, characterized by its features.

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