Washing machine and washing method

Abstract

To provide a washing machine which enables improvement of washing efficiency.SOLUTION: A washing machine propagates ultrasonic waves to liquid which contacts with an object to wash the object and includes: a washing tank in which the liquid is stored; an ultrasonic oscillation part which is provided so as to contact with the liquid stored in the washing tank; and a plurality of vibrators which provides ultrasonic vibration to the ultrasonic oscillation part. The propagation of the ultrasonic waves applied to the liquid from the ultrasonic oscillation part can be controlled by phased array control of the vibrators.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cleaning machine that cleans an object by propagating ultrasonic waves through a liquid, and a cleaning method that cleans an object by propagating ultrasonic waves through a liquid. [Background technology]

[0002] A wafer on which a plurality of devices are formed is divided and diced to produce device chips each including a device. A package substrate is formed by mounting a plurality of device chips on a predetermined substrate and covering and sealing the mounted device chips with a resin layer (mold resin). A package device including a plurality of packaged device chips is manufactured by dividing and dicing this package substrate. The device chips and package devices are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] When dividing a workpiece such as a wafer or a package substrate into chips, the workpiece is processed by various processing devices. For example, a cutting device that cuts the workpiece with an annular cutting blade, a laser processing device that performs laser processing on the workpiece, etc. are used to divide the workpiece. Also, a grinding device is used to grind and thin the workpiece before division, thereby obtaining thin chips.

[0004] When a workpiece is processed by the above-mentioned processing device, chips (processing chips) generated by the processing fly off and adhere to the workpiece. Therefore, after the processing of the workpiece, a cleaning step is performed to clean the workpiece. For example, an ultrasonic cleaner is used to clean the workpiece (see Patent Document 1). The ultrasonic cleaner includes a cleaning tank that stores a cleaning liquid (cleaning liquid), and cleans the workpiece by applying ultrasonic vibrations to the cleaning liquid while the workpiece is placed in the cleaning liquid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-363368 A Summary of the Invention [Problem to be solved by the invention]

[0006] When an object such as a workpiece processed by a processing device is placed in the cleaning tank of an ultrasonic cleaner and ultrasonic vibrations are applied to the cleaning liquid stored in the cleaning tank, the ultrasonic vibrations are transmitted to the object through the cleaning liquid and impacts are applied to foreign matter such as processing debris adhering to the object, causing the foreign matter to detach from the object and cleaning the entire object.

[0007] However, depending on the structure of the object, the material of the object, the processing applied to the object, etc., foreign matter may not adhere uniformly over the entire object, but may adhere intensively to a part of the object. In this case, it is necessary to continue cleaning the entire object by operating the ultrasonic cleaner until the foreign matter adhering to the part of the object is removed. This may result in a longer cleaning time for the object and a decrease in cleaning efficiency.

[0008] The present invention has been made in consideration of the above problems, and has an object to provide a cleaning machine and a cleaning method that can improve cleaning efficiency. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a cleaning machine that cleans an object by propagating ultrasonic waves to a liquid in contact with the object, the cleaning machine comprising: a cleaning tank for storing the liquid; an ultrasonic oscillator unit arranged to contact the liquid stored in the cleaning tank; and a plurality of transducers that impart ultrasonic vibrations to the ultrasonic oscillator unit, and the cleaning machine is capable of controlling the propagation of ultrasonic waves imparted to the liquid from the ultrasonic oscillator unit by phased array control of the plurality of transducers.

[0010] Preferably, the cleaning machine is capable of converging the ultrasonic waves applied from the ultrasonic oscillator to the liquid at an arbitrary position in the area in which the object is placed, and is also preferably capable of converging the ultrasonic waves applied from the ultrasonic oscillator to the liquid at the surface of the object to be cleaned.

[0011] According to another aspect of the present invention, there is provided a cleaning method for cleaning an object by propagating ultrasonic waves to a liquid in contact with the object, the cleaning method comprising: a preparation step of preparing a cleaning machine including a cleaning tank for storing the liquid, an ultrasonic oscillator unit arranged to be in contact with the liquid stored in the cleaning tank, and a plurality of transducers for imparting ultrasonic vibrations to the ultrasonic oscillator unit; an arrangement step of arranging the object so that it is in contact with the liquid stored in the cleaning tank; and a cleaning step of cleaning the object that is arranged to be in contact with the liquid, wherein in the cleaning step, the propagation of ultrasonic waves imparted to the liquid from the ultrasonic oscillator unit is controlled by phased array control of the plurality of transducers.

[0012] Preferably, in the cleaning step, the ultrasonic waves applied from the ultrasonic oscillator to the liquid are focused at an arbitrary position on the object, and more preferably, in the cleaning step, the ultrasonic waves applied from the ultrasonic oscillator to the liquid are focused on the surface of the object to be cleaned. Effect of the Invention

[0013] A cleaning machine according to an aspect of the present invention is configured to be capable of controlling the propagation of ultrasonic waves applied to a liquid by phased array control of a plurality of transducers. In addition, in a cleaning method according to an aspect of the present invention, the propagation of ultrasonic waves applied to a liquid is controlled by phased array control of a plurality of transducers. This makes it possible to preferentially apply ultrasonic vibrations to a desired area of ​​an object, improving the cleaning efficiency of the object. [Brief description of the drawings]

[0014] [Figure 1]FIG. 1(A) is a perspective view showing the top side of the cleaning machine, and FIG. 1(B) is a perspective view showing the bottom side of the cleaning machine. [Diagram 2] FIG. 1 is a cross-sectional view showing a cleaning machine for cleaning an object. [Diagram 3] FIG. 3A is a cross-sectional view showing how ultrasonic waves converge at the center of an object, and FIG. 3B is a cross-sectional view showing how ultrasonic waves converge at the outer periphery of the object. [Figure 4] Figure 4(A) is a contour diagram showing the sound pressure of ultrasound generated by phased array control with the phase difference set to 0°, Figure 4(B) is a contour diagram showing the sound pressure of ultrasound generated by phased array control with the phase difference set to 45°, Figure 4(C) is a contour diagram showing the sound pressure of ultrasound generated by phased array control with the phase difference set to 90°, and Figure 4(D) is a contour diagram showing the sound pressure of ultrasound generated by phased array control with the phase difference set to 135°. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of a cleaner according to this embodiment will be described. FIG. 1(A) and FIG. 1(B) show a cleaner (cleaning device) 2 for cleaning an object 11. FIG. 1(A) is a perspective view showing the top side of the cleaner 2, and FIG. 1(B) is a perspective view showing the bottom side of the cleaner 2. In addition, in FIG. 1(A) and FIG. 1(B), the X-axis direction (left-right direction, first horizontal direction) and the Y-axis direction (front-back direction, second horizontal direction) are mutually perpendicular. In addition, the Z-axis direction (up-down direction, height direction, vertical direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0016] The object 11 is an object to be cleaned by the cleaner 2. For example, the object 11 corresponds to a workpiece to be processed by cutting, grinding, polishing, laser processing, etc. After the predetermined processing is performed on the object 11, the object 11 is cleaned by the cleaner 2.

[0017] For example, the object 11 is a disk-shaped wafer made of a semiconductor material such as single crystal silicon, and has a first surface 11a and a second surface 11b that are generally parallel to each other. The object 11 is divided into a plurality of rectangular regions by a plurality of streets (planned division lines) arranged in a lattice pattern so as to intersect with each other. Devices (not shown), such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices, are formed in each of the regions divided by the streets.

[0018] A plurality of device chips, each equipped with a device, are manufactured by dividing the object 11 along the streets by cutting, laser processing, etc. Also, if the object 11 is thinned by grinding or polishing before being divided, a thinned device chip can be obtained.

[0019] However, there are no limitations on the type, material, size, shape, structure, etc. of the object 11. For example, the object 11 may be a wafer (substrate) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. In addition, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of devices, and the object 11 does not necessarily have to have devices formed thereon.

[0020] Furthermore, the target object 11 may be a package substrate such as a CSP (Chip Size Package) substrate or a QFN (Quad Flat Non-leaded package) substrate. For example, a package substrate is formed by mounting a plurality of device chips on a predetermined substrate and covering and sealing the mounted device chips with a resin layer (mold resin). By dividing and singulating the package substrate, a package device including a plurality of packaged device chips is manufactured.

[0021] Various processing devices are used for processing the object 11. Examples of the processing devices include a cutting device that cuts the object 11, a grinding device that grinds the object 11, a polishing device that polishes the object 11, a laser processing device that performs laser processing on the object 11, and the like.

[0022] The cutting device includes a processing unit (cutting unit) that cuts the object 11. The cutting unit includes a spindle, and an annular cutting blade is attached to the tip of the spindle. The cutting blade is rotated and cuts into the object 11, thereby cutting the object 11.

[0023] The grinding device includes a processing unit (grinding unit) that grinds the object 11. The grinding unit includes a spindle, and an annular grinding wheel including a plurality of grinding stones is attached to the tip of the spindle. The object 11 is ground by bringing the grinding stones into contact with the object 11 while rotating the grinding wheel.

[0024] The polishing device includes a processing unit (polishing unit) that polishes the object 11. The polishing unit includes a spindle, and a disk-shaped polishing pad is attached to the tip of the spindle. The object 11 is polished by rotating the polishing pad and bringing it into contact with the object 11.

[0025] The laser processing device includes a processing unit (laser irradiation unit) that irradiates a laser beam onto the object 11. For example, the laser irradiation unit includes a laser oscillator and a condenser that condenses the laser beam emitted from the laser oscillator. The laser beam irradiated from the laser irradiation unit is condensed on the first surface 11a, the second surface 11b, or inside the object 11, whereby the object 11 is subjected to laser processing.

[0026] When the object 11 is processed by the processing device as described above, scraps (processing scraps) generated by the processing adhere to the object 11. After the processing of the object 11 is completed, the object 11 is transported to the cleaning machine 2 and cleaned by the cleaning machine 2. This washes away foreign matter such as processing scraps adhering to the object 11. The cleaning machine 2 may be mounted on the processing device, or may be installed independently of the processing device.

[0027] The cleaner 2 includes a cleaning tank 4 that stores a cleaning liquid (cleaning liquid) 8. For example, the cleaning tank 4 is a rectangular parallelepiped container (tank) made of a metal such as stainless steel, and has an upper surface 4a and a lower surface 4b. As shown in FIG. 1(A), a storage section (recess) 6 that opens at the upper surface 4a of the cleaning tank 4 is provided inside the cleaning tank 4. For example, the storage section 6 is formed in a rectangular parallelepiped shape and includes a rectangular bottom surface 6a (see FIG. 2). When cleaning an object 11 with the cleaner 2, the liquid 8 is injected and stored in the storage section 6, and the object 11 is placed in the storage section 6.

[0028] As long as the liquid 8 can be stored in the storage section 6 and the object 11 can be put into the storage section 6, there are no limitations on the material of the cleaning tank 4 and the shapes, dimensions, etc. of the cleaning tank 4 and the storage section 6. For example, the cleaning tank 4 may be a cylindrical container, and the cleaning tank 4 may be provided with a cylindrical storage section 6.

[0029] The cleaning tank 4 may also be provided with a supply port (not shown) for supplying the liquid 8 to the storage section 6, and a discharge port (not shown) for discharging the liquid 8 from the storage section 6. The supply port is connected via a supply path to a liquid supply source (not shown) that supplies the liquid 8. The discharge port is connected to a discharge path. The supply path and the discharge path correspond to piping constituted by tubes, pipes, etc.

[0030] The liquid 8 is a cleaning liquid for cleaning the object 11, and the material of the liquid 8 is appropriately selected depending on the object 11. For example, pure water is used as the liquid 8. The liquid 8 may also contain a surfactant that promotes cleaning of the object 11.

[0031] 1(B), a vibration imparting unit (ultrasonic irradiation unit) 10 is provided on the underside 4b of the cleaning tank 4. The vibration imparting unit 10 imparts ultrasonic vibrations (vibrations at a frequency belonging to the ultrasonic band) to the liquid 8 stored in the storage section 6 by irradiating the liquid 8 with ultrasonic waves. The vibration imparting unit 10 includes an ultrasonic oscillator (vibration section) 12 provided so as to be in contact with the liquid 8 stored in the cleaning tank 4, and a plurality of vibrators 14 that impart ultrasonic vibrations to the ultrasonic oscillator section 12.

[0032] In this embodiment, a part of the cleaning tank 4 functions as the ultrasonic oscillator 12. Specifically, the bottom (bottom wall) including the lower surface 4b of the cleaning tank 4 is used as a plate-shaped vibration plate that applies vibration to the liquid 8. In this case, the lower surface 4b of the cleaning tank 4 corresponds to the outer surface (lower surface) of the ultrasonic oscillator 12, and the bottom surface 6a (see FIG. 2) of the storage portion 6 corresponds to the inner surface (upper surface) of the ultrasonic oscillator 12. The outer surface and the inner surface of the ultrasonic oscillator 12 are generally parallel, and the thickness of the ultrasonic oscillator 12 is generally uniform. The inner surface of the ultrasonic oscillator 12 contacts the liquid 8 stored in the cleaning tank 4. However, the ultrasonic oscillator 12 may be formed of a member separate from the cleaning tank 4 and attached to the cleaning tank 4.

[0033] The multiple transducers 14 are connected to the outer surface side (the lower surface 4b side of the cleaning tank 4) of the ultrasonic oscillator 12. For example, the transducer 14 is a piezoelectric element that vibrates when a voltage is applied, and includes a piezoelectric ceramic such as lead zirconate titanate (PZT) and electrodes that apply a voltage to the piezoelectric ceramic.

[0034] The arrangement of the multiple transducers 14 is set so that multiple transducers 14 are installed at different distances from the center (intersection of diagonals on the outer surface) of the ultrasonic oscillator 12. For example, Fig. 1(B) illustrates an example in which 9 rows and 9 columns (a total of 81 transducers 14) are arranged at predetermined intervals along two mutually perpendicular directions (X-axis direction and Y-axis direction). In this case, transducers 14 that are the same distance from the center of the ultrasonic oscillator 12 and transducers 14 that are different distances from the center of the ultrasonic oscillator 12 are installed in a mixed manner.

[0035] However, the number and arrangement of the transducers 14 are not limited to the above. For example, a plurality of virtual annular lines having different diameters may be concentrically set on the outer surface of the ultrasonic oscillator 12, and a plurality of transducers 14 may be arranged annularly on each of the annular lines. In this case, the transducers 14 arranged on the same annular line are installed so that they are equally distant from the center of the ultrasonic oscillator 12. On the other hand, the transducers 14 arranged on different annular lines are installed so that they are differently distant from the center of the ultrasonic oscillator 12.

[0036] The cleaner 2 also includes an ultrasonic oscillator 16 that controls the application of ultrasonic vibrations from the vibration applying unit 10 to the liquid 8. The ultrasonic oscillator 16 is connected to the multiple transducers 14, and oscillates ultrasonic waves to supply high-frequency power to the multiple transducers 14. This causes each of the multiple transducers 14 to vibrate at a frequency (20 kHz or higher) that belongs to the ultrasonic band.

[0037] Furthermore, the cleaner 2 includes a controller (control unit, control section, control device) 18 that controls the cleaner 2. The controller 18 is connected to each component (vibration imparting unit 10, ultrasonic oscillator 16, etc.) that configures the cleaner 2, and operates the cleaner 2 by outputting control signals to each component of the cleaner 2.

[0038] For example, the controller 18 is configured by a computer. Specifically, the controller 18 includes a processing unit that executes processes such as calculations required for the operation of the cleaner 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the cleaner 2. The processing unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). When the cleaner 2 is mounted on a processing device, the controller of the processing device may have the function of the controller 18.

[0039] The high frequency power supplied from the ultrasonic oscillator 16 to the multiple transducers 14 is set by the controller 18 controlling the ultrasonic oscillator 16. In this way, the ultrasonic vibration of the multiple transducers 14 is controlled by the controller 18. However, the ultrasonic oscillator 16 may also autonomously set the high frequency power supplied to the multiple transducers 14 to control the ultrasonic vibration of the multiple transducers 14.

[0040] When the liquid 8 is injected into the storage section 6 of the cleaning tank 4 and the storage section 6 is filled with the liquid 8, the liquid 8 comes into contact with the inner surface of the ultrasonic oscillator 12 (the bottom surface 6a of the storage section 6, see FIG. 2). In this state, when high-frequency power is supplied from the ultrasonic oscillator 16 to the transducers 14, the transducers 14 vibrate at a frequency that belongs to the ultrasonic band, and the ultrasonic vibrations emitted by the transducers 14 propagate through the ultrasonic oscillator 12 and reach the liquid 8. As a result, ultrasonic waves are irradiated from the ultrasonic oscillator 12 to the liquid 8. The ultrasonic waves then propagate through the liquid 8, thereby applying ultrasonic vibrations to the liquid 8.

[0041] Here, the cleaning machine 2 according to this embodiment is configured to be capable of controlling the propagation of ultrasonic waves applied from the ultrasonic oscillator 12 to the liquid 8 by phased array control of the multiple transducers 14. This allows ultrasonic vibrations to be applied preferentially to a desired area of ​​the object 11.

[0042] 2 is a cross-sectional view showing the cleaner 2 cleaning the object 11. When the object 11 is cleaned by the cleaner 2, the object 11 is put into the reservoir 6 of the cleaning tank 4, in which the liquid 8 is stored, and is placed in the liquid 8. For example, when cleaning the second surface 11b side of the object 11, the object 11 is held in the liquid 8 so that the first surface 11a faces upward and the second surface 11b (the surface to be cleaned) faces the ultrasonic oscillator 12.

[0043] 2, the object 11 is immersed in the liquid 8 so that the entire object 11 (first surface 11a, second surface 11b and side surfaces) is in contact with the liquid 8. However, the object 11 may be arranged so that only a part of the object 11 including the surface to be cleaned is immersed in the liquid 8. Furthermore, when cleaning the first surface 11a side of the object 11, the object 11 is arranged so that the first surface 11a (surface to be cleaned) faces the ultrasonic oscillator 12.

[0044] There is no limitation on the method of holding the object 11 in the liquid 8. For example, a holding member (not shown) for holding the object 11 is provided in the storage section 6 of the cleaning tank 4. As the holding member, a plate-like member having a mesh structure made of metal or the like can be used. In this case, the object 11 is placed on the holding member and is supported from below by the holding member in the liquid 8.

[0045] Furthermore, instead of the above-mentioned holding member, the cleaning machine 2 may include a holding unit (not shown) installed outside the cleaning tank 4. For example, the holding unit includes a holding portion such as a holding pad or a clamp mechanism for holding the object 11, and a moving mechanism such as a transport arm for moving the holding portion. The holding unit then moves the holding portion holding the object 11 into the reservoir 6 of the cleaning tank 4 by the moving mechanism, and stops it in the liquid 8.

[0046] Next, with the object 11 placed in the liquid 8, ultrasonic vibrations are applied to the liquid 8 by the vibration applying unit 10. The ultrasonic vibrations are then transmitted to the object 11 using the liquid 8 as a medium, and impact foreign matter adhering to the surface to be cleaned of the object 11. As a result, the foreign matter adhering to the object 11 is detached from the object 11 and removed.

[0047] 3(A) and 3(B) show how ultrasonic waves propagate through the liquid 8. In addition, Fig. 3(A) and 3(B) also show a reference line 20 passing through the center of the storage section 6 of the cleaning tank 4. The reference line 20 is perpendicular to the bottom surface 6a of the storage section 6 (the inner surface of the ultrasonic oscillator 12) and corresponds to an imaginary straight line passing through the centers of the storage section 6 and the ultrasonic oscillator 12.

[0048] When high-frequency power is supplied from the ultrasonic oscillator 16 (see FIG. 2) to the multiple transducers 14, the multiple transducers 14 vibrate and impart ultrasonic vibration to the ultrasonic oscillator section 12. As a result, the ultrasonic vibration propagates to the liquid 8 via the ultrasonic oscillator section 12, and multiple ultrasonic waves 22 are irradiated from the ultrasonic oscillator section 12 to the liquid 8. The multiple ultrasonic waves 22 are then synthesized to generate an ultrasonic wave (synthetic wave) 24 that propagates through the liquid 8. The ultrasonic wave 24 propagates through the liquid 8 as a medium, imparting ultrasonic vibration to the liquid 8.

[0049] Here, the ultrasonic oscillator 16 controls the propagation of ultrasonic waves in the liquid 8 by phased array control of the multiple transducers 14. Phased array control is a control that adjusts the propagation direction, convergence position, etc. of ultrasonic waves by controlling the phase of ultrasonic vibrations emitted by the multiple transducers 14 for each transducer 14. By phased array control of the multiple transducers 14, ultrasonic waves 24 applied to the liquid 8 from the ultrasonic oscillator 12 can be converged at any position in the area where the object 11 is placed. This makes it possible to focus on cleaning a desired area of ​​the object 11.

[0050] 3(A) is a cross-sectional view showing how ultrasonic waves 24 converge at the center of the object 11. When foreign matter is attached only to the center of the object 11, or when more foreign matter is attached to the center of the object 11 than to other regions, it is preferable to use phased array control to converge the ultrasonic waves 24 at the center of the object 11. This allows ultrasonic vibrations to be preferentially applied to the center of the object 11, and the object 11 is efficiently cleaned.

[0051] Specifically, the ultrasonic oscillator 16 supplies high-frequency power to the multiple transducers 14 so that the ultrasonic vibration emitted by the transducer 14 closer to the center of the ultrasonic oscillator 12 (the transducer 14 closer to the center of the target object 11) is delayed in phase. As a result, the ultrasonic waves 22 generated at positions closer to the center of the ultrasonic oscillator 12 are delayed in phase. The multiple ultrasonic waves 22 are then synthesized to generate an ultrasonic wave 24 that propagates through the liquid 8 along the reference line 20 and converges.

[0052] When the multiple transducers 14 are controlled as described above, the ultrasonic waves 24 converge on the reference line 20. For example, a phase difference between the ultrasonic vibrations emitted by the multiple transducers 14 is set so that the ultrasonic waves 24 converge at a convergence position (focal point) 26A located at the center of the surface to be cleaned (second surface 11b) of the object 11. As a result, the ultrasonic vibration is applied intensively to the center of the object 11, and foreign matter attached to the center of the object 11 is removed in a short time.

[0053] 3(B) is a cross-sectional view showing how the ultrasonic waves 24 converge at the outer periphery of the object 11. When foreign matter is attached only to the outer periphery of the object 11, or when more foreign matter is attached to the outer periphery of the object 11 than to other regions, it is preferable to use phased array control to converge the ultrasonic waves 24 at the outer periphery of the object 11. This allows ultrasonic vibration to be preferentially applied to the outer periphery of the object 11, and the object 11 is efficiently cleaned.

[0054] Specifically, the ultrasonic oscillator 16 supplies high-frequency power to the multiple transducers 14 so that the phase of the ultrasonic vibration emitted by the transducer 14 (the transducer 14 closer to the outer periphery of the target object 11) closer to one end (the left end in FIG. 3(B)) of the ultrasonic oscillator 12 is delayed. As a result, the phase of the ultrasonic waves 22 generated at positions closer to one end of the ultrasonic oscillator 12 is delayed. The multiple ultrasonic waves 22 are then combined to generate an ultrasonic wave 24 that propagates through the liquid 8 in a direction inclined relative to the reference line 20 (a direction toward the upper left in FIG. 3(B)) and converges.

[0055] When the multiple transducers 14 are controlled as described above, the ultrasonic waves 24 converge at a position away from the reference line 20. For example, a phase difference between the ultrasonic vibrations emitted by the multiple transducers 14 is set so that the ultrasonic waves 24 converge at a convergence position (focal point) 26B located on the outer periphery of the surface to be cleaned (second surface 11b) of the object 11. As a result, the ultrasonic vibration is applied intensively to the outer periphery of the object 11, and foreign matter attached to the outer periphery of the object 11 is removed in a short time.

[0056] As described above, by adjusting the phase difference of ultrasonic vibrations emitted by the multiple transducers 14 by phased array control, the ultrasonic waves 24 can be converged at a desired position depending on the distance between the object 11 and the ultrasonic oscillator 12, the position and distribution (range) of foreign matter attached to the object 11, etc. The convergence position of the ultrasonic waves 24 is not limited as long as it is in the liquid 8. For example, the convergence position of the ultrasonic waves 24 may be set on the ultrasonic oscillator 12 side of the surface of the object 11 to be cleaned (the lower side in Figs. 3(A) and 3(B)), or may be set on the opposite side of the ultrasonic oscillator 12 from the surface of the object 11 to be cleaned (the upper side in Figs. 3(A) and 3(B)).

[0057] Furthermore, while the object 11 is being cleaned (while ultrasonic vibrations are being applied), the object 11 may be moved or rotated, or the phase difference of the ultrasonic vibrations emitted by the multiple transducers 14 may be varied. This allows ultrasonic vibrations to be applied sequentially to different parts of the object 11. For example, by rotating the object 11 with the ultrasonic waves 24 converged at the convergence position 26B (see FIG. 3(B)), ultrasonic vibrations can be applied to the entire outer periphery of the object 11.

[0058] Next, an example of ultrasonic wave propagation control by phased array control will be described with reference to Fig. 4(A) to Fig. 4(D). As an example, the sound pressure of ultrasonic waves propagating through liquid when five transducers 14 are operated by phased array control will be described.

[0059] 4(A) to 4(D) show contour diagrams 30A to 30D of the sound pressure [MPa] of ultrasonic waves propagating through liquid when four different types of phased array control are performed. In the contour diagrams 30A to 30D, the maximum value (positive value) of the ultrasonic sound pressure is displayed in white, and the minimum value (negative value) of the ultrasonic sound pressure is displayed in black.

[0060] The numerical values ​​attached to the transducers 14 in Figures 4(A) to 4(D) indicate the phase difference (phase delay) of the ultrasound with respect to 0° as the reference. Furthermore, the reference line 32 is an imaginary straight line that is perpendicular to the inner surface (upper surface) of the ultrasound oscillator 12 and passes through the center of the ultrasound oscillator 12, and corresponds to the reference line 20 (see Figures 3(A) and 3(B)). The contour diagrams 30B to 30D (Figures 4(B) to 4(D)) show the sound pressure of the ultrasound when phased array control is performed so that the ultrasonic vibration of the transducers 14 closer to the reference line 32 has a greater phase delay.

[0061] 4(A) is a contour diagram 30A showing the sound pressure of ultrasonic waves generated by phased array control with a phase difference set to 0°. When there is no phase difference between ultrasonic vibrations emitted by multiple transducers 14, the ultrasonic waves (composite waves) propagate through the liquid along reference line 32 but do not converge on reference line 32. Therefore, the sound pressure of the ultrasonic waves is unlikely to increase or decrease on reference line 32, and the phenomenon in which high-intensity ultrasonic waves are partially irradiated on a part of an object placed on reference line 32 is unlikely to occur.

[0062] FIG. 4(B) is a contour diagram 30B showing the sound pressure of ultrasonic waves generated by phased array control with a phase difference set to 45°. FIG. 4(C) is a contour diagram 30C showing the sound pressure of ultrasonic waves generated by phased array control with a phase difference set to 90°. When the phase difference of ultrasonic vibrations emitted by multiple transducers 14 is set to 45° or 90°, ultrasonic waves (composite waves) converge on or near the reference line 32. As a result, the sound pressure increases or decreases significantly on or near the reference line 32, taking maximum and minimum values, and high-intensity ultrasonic waves are partially irradiated onto a part of the object placed on the reference line 32.

[0063] 4(D) is a contour diagram 30D showing the sound pressure of ultrasonic waves generated by phased array control with a phase difference set to 135°. Even when the phase difference of ultrasonic vibrations emitted by multiple transducers 14 is set to 135°, the ultrasonic waves (composite wave) converge on or near the reference line 32. However, compared to when the phase difference is 45° or 90°, the ultrasonic waves converge at a position closer to the ultrasonic oscillator 12.

[0064] By controlling the propagation direction and convergence position of the ultrasonic waves 24 in the liquid 8 by the above-mentioned phased array control (see Figs. 3(A) and 3(B)), the ultrasonic waves 24 can be converged at any position in the area where the object 11 is placed. This makes it possible to apply ultrasonic vibrations in a focused manner to any position of the object 11.

[0065] Next, a specific example of the method for cleaning an object according to this embodiment will be described. In this embodiment, the object 11 is cleaned using the above-mentioned cleaner 2. Details of the method for cleaning the object 11 using the cleaner 2 have already been described, but the procedure for cleaning the object 11 will be summarized and described again below.

[0066] When cleaning an object 11 by the cleaning method according to this embodiment, first, a cleaning machine 2 is prepared (preparation step). In the preparation step, a cleaning machine 2 (see FIG. 1(A)) is prepared in a state in which a liquid 8 is stored in a cleaning tank 4. Note that a practitioner of the cleaning method may manufacture the cleaning machine 2 himself or herself, or may obtain the cleaning machine 2 from an equipment manufacturer or the like.

[0067] Next, the object 11 is placed so as to be in contact with the liquid 8 stored in the cleaning tank 4 (placement step). In the placement step, the object 11 is held so that the surface to be cleaned of the object 11 faces the ultrasonic oscillator 12 (see FIG. 2). As described above, the object 11 may be held by a holding member provided in the reservoir 6 of the cleaning tank 4, or may be held by a holding unit installed outside the cleaning tank 4.

[0068] For example, when cleaning the second surface 11b side of the object 11, the object 11 is held in the liquid 8 so that the first surface 11a faces upward and the second surface 11b faces the ultrasonic oscillator 12. At this time, the object 11 may be arranged so that the entire object 11 is immersed in the liquid 8, or so that only a partial area of ​​the object 11 including the surface to be cleaned is immersed in the liquid 8.

[0069] Next, the object 11 arranged so as to be in contact with the liquid 8 is washed (washing step). In the washing step, the propagation of ultrasonic waves applied from the ultrasonic oscillator 12 to the liquid 8 is controlled by phased array control of the multiple transducers 14 (see Figs. 3(A) and 3(B)).

[0070] In the cleaning step, ultrasonic waves 24 applied from the ultrasonic oscillator 12 to the liquid 8 are focused at an arbitrary position on the object 11 by phased array control of the multiple transducers 14. In particular, it is preferable that the ultrasonic waves 24 are focused on the surface to be cleaned (second surface 11b) of the object 11. For example, when cleaning is focused on the center of the object 11, the ultrasonic waves 24 are focused on the center of the surface to be cleaned of the object 11 (see FIG. 3(A)). On the other hand, when cleaning is focused on the outer periphery of the object 11, the ultrasonic waves 24 are focused on the outer periphery of the surface to be cleaned of the object 11 (see FIG. 3(B)). This allows foreign matter concentratively attached to a part of the object 11 to be efficiently removed.

[0071] After ultrasonic vibrations have been applied to the object 11 for a certain period of time, the supply of high-frequency power from the ultrasonic oscillator 16 to the multiple transducers 14 is stopped, and the application of ultrasonic vibrations from the multiple transducers 14 to the ultrasonic oscillator unit 12 is stopped. This completes the cleaning of the object 11. The object 11 is then removed from the cleaning tank 4 and transported to a predetermined location.

[0072] As described above, the cleaning machine 2 according to this embodiment is configured to be able to control the propagation of ultrasonic waves applied to the liquid 8 by phased array control of the multiple transducers 14. Moreover, in a cleaning method according to one aspect of the present invention, the propagation of ultrasonic waves applied to the liquid 8 is controlled by phased array control of the multiple transducers 14. This makes it possible to preferentially apply ultrasonic vibrations to a desired region of the object 11, improving the cleaning efficiency of the object 11.

[0073] In the above embodiment, the bottom (bottom wall) of the cleaning tank 4 is used as the ultrasonic oscillator 12. However, the installation position of the ultrasonic oscillator 12 can be changed as appropriate depending on the position and orientation of the object 11 held in the liquid 8.

[0074] For example, among the four side parts (side walls) arranged perpendicular to the bottom of the cleaning tank 4, a pair of mutually opposing side parts (for example, the left side wall and the right side wall in FIG. 2) may be used as the ultrasonic oscillators 12. In this case, a plurality of vibrators 14 are connected to one ultrasonic oscillator 12 and the other ultrasonic oscillator 12, respectively, to configure two pairs of vibration imparting units 10. The object 11 is placed in the liquid 8 so that the first surface 11a faces one ultrasonic oscillator 12 and the second surface 11b faces the other ultrasonic oscillator 12. In this case, the object 11 is placed vertically so that the first surface 11a and the second surface 11b are approximately parallel to the Z-axis direction.

[0075] When the cleaning machine 2 is configured as described above and the object 11 is placed therein, and the two vibration imparting units 10 are operated simultaneously, ultrasonic waves are simultaneously irradiated from the pair of ultrasonic oscillators 12 to the liquid 8, and ultrasonic vibrations are simultaneously imparted to the first surface 11a and the second surface 11b of the object 11. This allows cleaning of the first surface 11a side and the second surface 11b side of the object 11 to be performed simultaneously, improving the efficiency of the cleaning process.

[0076] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0077] 11 Target object (object to be cleaned, object to be processed) 11a 1st page 11b Side 2 2. Cleaning machine (cleaning equipment) 4. Cleaning tank 4a Top side 4b Bottom side 6 Reservoir (recess) 6a Bottom 8 Liquid (cleaning liquid) 10. Vibration unit (ultrasonic irradiation unit) 12 Ultrasonic oscillator (vibration unit) 14 Transducer 16 Ultrasonic oscillator 18 Controller (control unit, control section, control device) 20 Reference Line 22 Ultrasound 24 Ultrasound (synthetic wave) 26A, 26B Convergence position (focal point) 30A, 30B, 30C, 30D Contour diagram 32 Reference Line

Claims

1. A cleaning machine that cleans an object by propagating ultrasonic waves through a liquid that contacts the object, A cleaning tank for storing the liquid; an ultrasonic oscillator provided so as to come into contact with the liquid stored in the cleaning tank; A plurality of transducers for applying ultrasonic vibration to the ultrasonic oscillator, A cleaning machine characterized in that the propagation of ultrasonic waves applied to the liquid from the ultrasonic oscillator can be controlled by phased array control of a plurality of the transducers.

2. 2. The cleaning machine according to claim 1, wherein the ultrasonic waves applied to the liquid from the ultrasonic oscillator can be focused at any position in the area where the object is placed.

3. 3. The cleaning machine according to claim 1, wherein the ultrasonic wave applied to the liquid from the ultrasonic oscillator is capable of being focused on the surface of the object to be cleaned.

4. A cleaning method for cleaning an object by propagating ultrasonic waves through a liquid in contact with the object, comprising: a preparation step of preparing a cleaning machine including a cleaning tank for storing the liquid, an ultrasonic oscillator provided so as to come into contact with the liquid stored in the cleaning tank, and a plurality of vibrators for applying ultrasonic vibrations to the ultrasonic oscillator; a positioning step of positioning the object so as to come into contact with the liquid stored in the cleaning tank; A cleaning step of cleaning the object arranged to be in contact with the liquid, The cleaning method is characterized in that in the cleaning step, propagation of ultrasonic waves applied to the liquid from the ultrasonic oscillator is controlled by phased array control of a plurality of the transducers.

5. 5. The cleaning method according to claim 4, wherein in the cleaning step, the ultrasonic waves applied to the liquid from the ultrasonic oscillator are focused at an arbitrary position on the object.

6. 6. The cleaning method according to claim 4, wherein in the cleaning step, the ultrasonic waves applied to the liquid from the ultrasonic oscillator are converged on the surface of the object to be cleaned.

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