Method for determining deterioration of ultrasonic transducer and processing apparatus

Abstract

To provide a method for determining deterioration of an ultrasonic transducer and a processing apparatus capable of reliably and easily measuring characteristic changes of the ultrasonic transducer.SOLUTION: There is provided a method for determining deterioration of an ultrasonic transducer that detects, in a processing apparatus mounted with the ultrasonic transducer, deterioration of the ultrasonic transducer mounted on the processing apparatus. The method comprises: a calculation step 1 of calculating an acoustic conversion efficiency of the ultrasonic transducer; a setting step 2 of setting a threshold value of the acoustic conversion efficiency serving as a reference for determining acceptance or rejection of the ultrasonic transducer; and a determination step 3 of determining that the ultrasonic transducer is deteriorated when the acoustic conversion efficiency calculated in the calculation step 1 is lower than the threshold value set in the setting step 2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method and a processing device for determining deterioration of an ultrasonic transducer. [Background technology]

[0002] The characteristics of ultrasonic vibrators that generate ultrasonic waves can change with use. In processing equipment that uses ultrasonic vibrators to perform processes such as cleaning and peeling (see, for example, Patent Documents 1 and 2), if such changes in the characteristics of the ultrasonic vibrator occur, the desired process may not be possible, so it is very important to understand these changes in characteristics. Therefore, a method for understanding the characteristics of the vibrator by measuring the sound pressure emitted from the ultrasonic vibrator into water has been studied. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-313939 [Patent Document 2] Japanese Patent Application Publication No. 2018-093106 Summary of the Invention [Problem to be solved by the invention]

[0004] However, sound pressure measurement has the problem of being uncertain due to many variable factors such as the influence of dissolved gas in the water and the influence of location. There is also a method of measuring the characteristics of the ultrasonic vibrator using a dedicated measuring device (impedance analyzer), but this requires direct connection between the ultrasonic vibrator and the measuring device, which requires the time and effort of removing the ultrasonic vibrator from the processing device, which is a problem.

[0005] The present invention has been made in consideration of the above problems, and its object is to provide a method and processing device for determining deterioration of an ultrasonic vibrator that can reliably and simply measure changes in the characteristics of the ultrasonic vibrator. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the method for determining deterioration of an ultrasonic vibrator of the present invention is a method for determining deterioration of an ultrasonic vibrator mounted on a processing device in which an ultrasonic vibrator is mounted, and is characterized by comprising: a calculation step for calculating the acoustic conversion efficiency of the ultrasonic vibrator; a setting step for setting a threshold value for the acoustic conversion efficiency that serves as a criterion for determining whether the ultrasonic vibrator is pass or fail; and a determination step for determining that the ultrasonic vibrator is degraded if the acoustic conversion efficiency calculated in the calculation step is lower than the threshold value set in the setting step.

[0007] Furthermore, in the method for determining deterioration of an ultrasonic vibrator of the present invention, it is preferable that the calculation step includes a first frequency characteristic acquisition step of acquiring the frequency characteristics of the ultrasonic vibrator in a predetermined frequency band in an unloaded state, a first resonance resistance calculation step of calculating the resonance resistance in the unloaded state from the information on the frequency characteristics acquired in the first frequency characteristic acquisition step, a second frequency characteristic acquisition step of acquiring the frequency characteristics of the ultrasonic vibrator in a predetermined frequency band in a loaded state, a second resonance resistance calculation step of calculating the resonance resistance in the loaded state from the information on the frequency characteristics acquired in the second frequency characteristic acquisition step, and an acoustic conversion efficiency calculation step of calculating the acoustic conversion efficiency based on the difference between the resonance resistance in the unloaded state and the resonance resistance in the loaded state.

[0008] Furthermore, the processing device of the present invention is a processing device equipped with an ultrasonic vibrator, and comprises an ultrasonic generating unit having the ultrasonic vibrator and an ultrasonic oscillator that inputs a specific frequency signal to the ultrasonic vibrator, and a controller that controls the ultrasonic generating unit, wherein the controller has a calculation unit that calculates the acoustic conversion efficiency of the ultrasonic vibrator, a memory unit that stores a threshold value of the acoustic conversion efficiency that serves as a criterion for determining whether the ultrasonic vibrator is pass or fail, and a judgment unit that judges that the ultrasonic vibrator is deteriorated if the acoustic conversion efficiency calculated by the calculation unit is lower than the threshold value stored in the memory unit.

[0009] Furthermore, in the processing device of the present invention, it is preferable that the controller further has a characteristic measuring unit that acquires the frequency characteristics of the ultrasonic vibrator in a predetermined frequency band, and the calculation unit calculates the resonance resistance in the unloaded state based on the frequency characteristics of the ultrasonic vibrator in the unloaded state acquired by the characteristic measuring unit, calculates the resonance resistance in the loaded state based on the frequency characteristics of the ultrasonic vibrator in the loaded state acquired by the characteristic measuring unit, and calculates the acoustic conversion efficiency based on the difference between the resonance resistance in the unloaded state and the resonance resistance in the loaded state.

[0010] Furthermore, the processing apparatus of the present invention may be a delamination apparatus comprising: a holding table for holding an ingot on which a delamination layer has been formed to a depth corresponding to the thickness of the wafer to be manufactured by irradiating it with a laser beam; an ultrasonic wave generating unit for applying ultrasonic waves to the ingot; a liquid supply unit for supplying liquid between the ultrasonic wave generating unit and the ingot; and a delamination unit for holding the wafer to be manufactured and moving it in a direction away from the ingot to delaminate the wafer to be manufactured from the ingot. [Effects of the Invention]

[0011] The present invention can reliably and easily measure changes in the characteristics of an ultrasonic transducer. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a processing apparatus according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of the configuration of the processing apparatus according to the embodiment. [Figure 3] FIG. 3 is a flowchart showing the flow of the method for determining deterioration of an ultrasonic transducer according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing the flow of the calculation steps shown in FIG. [Figure 5]FIG. 5 is a schematic diagram showing the first frequency characteristic acquisition step shown in FIG. [Figure 6] FIG. 6 is a graph showing an example of the relationship between the frequency band and the impedance and phase. [Figure 7] FIG. 7 is a schematic diagram showing the second frequency characteristic acquisition step shown in FIG. [Figure 8] FIG. 8 is a graph showing an example of the change in acoustic conversion efficiency. [Figure 9] FIG. 9 is a schematic diagram showing a first frequency characteristic acquisition step performed by a processing device according to a modified example. [Figure 10] FIG. 10 is a schematic diagram showing a second frequency characteristic acquisition step performed by a processing device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0014] [Embodiment] A method for determining deterioration of an ultrasonic vibrator 32 and a processing device 10 according to an embodiment of the present invention will be described with reference to the drawings. The method for determining deterioration of an ultrasonic vibrator 32 according to the embodiment is a method for determining whether or not the ultrasonic vibrator 32 mounted on the processing device 10 shown in Figures 1 and 2 has deteriorated.

[0015] (Processing device 10) First, the configuration of a processing apparatus 10 according to an embodiment of the present invention will be described. Figures 1 and 2 are schematic diagrams showing an example configuration of the processing apparatus 10 according to the embodiment. In the embodiment, the processing apparatus 10 is a delamination apparatus that delaminates a wafer 98 to be manufactured from an ingot 90. The processing apparatus 10 includes a holding table 20, an ultrasonic wave generating unit 30, a liquid supply unit 40, a delamination unit 50, and a controller 60.

[0016] The ingot 90 is made of SiC (silicon carbide), Si (silicon), LT (lithium tantalate), GaN (gallium nitride), Ga2O3 (gallium oxide), or the like, and is formed into a cylindrical shape as a whole. The ingot 90 has a first surface 92 and a second surface 94. The first surface 92 is circular and is one end surface of the cylindrical ingot 90. The second surface 94 is circular and is the end surface of the cylindrical ingot 90 opposite the first surface 92.

[0017] The ingot 90 has a delamination layer 96 at a predetermined depth from the first surface 92. The predetermined depth is equal to the thickness of the wafer 98 to be manufactured. The delamination layer 96 is formed, for example, by irradiating it with a laser beam. Specifically, the focal point of the laser beam is positioned at a depth from the first surface 92 of the ingot 90 that corresponds to the thickness of the wafer 98 to be manufactured, and the laser beam is irradiated onto the front surface along a horizontal plane. The laser beam has a wavelength that is transparent to the ingot 90. As a result, the delamination layer 96 is formed at a depth that corresponds to the thickness of the wafer 98 to be manufactured, the delamination layer 96 including a modified portion and cracks extending from the modified portion.

[0018] The holding table 20 holds the ingot 90 on a holding surface 22. The holding table 20 suction-holds the second surface 94 of the ingot 90 placed on the holding surface 22. The holding surface 22 has a disk shape made of porous ceramic or the like. In this embodiment, the holding surface 22 is a flat surface parallel to the horizontal direction. The holding surface 22 is connected to a vacuum suction source, for example, via a vacuum suction path.

[0019] The ultrasonic generating unit 30 is a unit that applies ultrasonic waves 38 to the ingot 90, thereby peeling off a part of the first surface 92 of the ingot 90 using a peeling layer 96 formed inside the ingot 90 as an interface, and manufacturing the peeled part as a wafer 98. The ultrasonic generating unit 30 of the embodiment applies ultrasonic waves 38 to the ingot 90 held on the holding surface 22 of the holding table 20. The ultrasonic generating unit 30 includes an ultrasonic vibrator 32 and an ultrasonic oscillator 34.

[0020] The ultrasonic vibrator 32 is made of piezoelectric ceramics or the like. When an AC voltage is applied to the piezoelectric ceramic, the ultrasonic vibrator 32 expands and contracts in a direction perpendicular to an end face 36 facing the holding surface 22 of the holding table 20, generating ultrasonic vibrations (vibrations whose frequency is equivalent to the frequency of ultrasonic waves). The ultrasonic oscillator 34 inputs a specific frequency signal to the ultrasonic vibrator 32. When the specific frequency signal is input from the ultrasonic oscillator 34 to the ultrasonic vibrator 32, the piezoelectric ceramic expands and contracts at that frequency, causing the end face 36 to vibrate.

[0021] The liquid supply unit 40 is a unit that supplies a liquid 42 between the ultrasonic vibrator 32 and the ingot 90 when the ultrasonic generating unit 30 applies ultrasonic waves 38 to the ingot 90 held on the holding surface 22 of the holding table 20. The liquid includes, for example, water.

[0022] When the ingot 90 is peeled at the peeling layer 96 by the ultrasonic wave generating unit 30, first, the second surface 94 side of the ingot 90 is suction-held on the holding surface 22 of the holding table 20. Next, the ultrasonic vibrator 32 of the ultrasonic wave generating unit 30 is made to face the first surface 92 of the ingot 90. Next, the liquid 42 is supplied from the liquid supply unit 40 between the ultrasonic vibrator 32 and the ingot 90.

[0023] In this state, a specific frequency signal is input from the ultrasonic oscillator 34 of the ultrasonic generating unit 30 to ultrasonically vibrate the ultrasonic vibrator 32, whereby ultrasonic vibrations of a frequency corresponding to the vibration of the ultrasonic vibrator 32 are propagated into the liquid 42 and applied to the ingot 90. By applying ultrasonic vibrations to the entire surface of the ingot 90, a portion of the first surface 92 side of the ingot 90 is peeled off with the peeling layer 96 as the interface.

[0024] The delamination unit 50 is a unit that delaminates a wafer 98, which is a part of the first surface 92 of the ingot 90, from the ingot 90, separated by the ultrasonic generating unit 30 at the separation layer 96 as an interface. The delamination unit 50 holds the ingot 90 on the holding surface 52. The delamination unit 50 suction-holds the first surface 92 of the ingot 90 placed on the holding surface 22 of the holding table 20. In other words, the delamination unit 50 suction-holds the wafer 98 to be manufactured.

[0025] The holding surface 52 of the peeling unit 50 is a disk-shaped surface made of porous ceramic or the like. In this embodiment, the holding surface 52 is a flat surface that is parallel to the horizontal direction and faces the holding surface 22 of the holding table 20. The holding surface 22 is connected to a vacuum suction source, for example, via a vacuum suction path.

[0026] The delamination unit 50 is capable of moving relatively close to and away from the holding table 20. The delamination unit 50 is also movable between a position retracted from above the holding table 20 (for example, the state shown in FIG. 1 ) and a position above the holding table 20. In this embodiment, the delamination unit 50 is capable of moving up and down in a direction perpendicular to the holding surface 22 of the holding table 20. The delamination unit 50 holds the wafer 98 to be manufactured and moves it in a direction away from the ingot 90, thereby delaminating the wafer 98 to be manufactured from the ingot 90.

[0027] The controller 60 controls the ultrasonic generating unit 30 and performs various calculations to determine deterioration of the ultrasonic transducer 32. The controller 60 is a well-known computer that includes, for example, an arithmetic processing device as a calculation means including a microprocessor such as a CPU (Central Processing Unit), a storage device as a storage means having memory such as an HDD (Hard Disk Drive), ROM (Read Only Memory) or RAM (Random Access Memory), and an input / output interface device as a communication means.

[0028] The controller 60 includes a characteristic measuring unit 62, a calculating unit 64, a storage unit 66, and a determining unit 68. The controller 60 also includes, for example, an input device operated by an operator to input data, a display device that displays predetermined video information, and a notification device that notifies predetermined notification information.

[0029] The characteristic measurement unit 62 measures and acquires the frequency characteristics of the ultrasonic transducer 32 in a predetermined frequency band in both an unloaded state and a loaded state. The frequency characteristics indicate the relationship between the impedance [Ω] and the frequency band [kHz]. The unloaded state indicates a state in which the ultrasonic transducer 32 is in air. The loaded state indicates a state in which the ultrasonic transducer 32 is in liquid 42.

[0030] The calculation unit 64 calculates the acoustic conversion efficiency η of the ultrasonic transducer 32. The calculation unit 64 calculates the resonance resistance R0 [Ω] in the unloaded state based on the frequency characteristics of the ultrasonic transducer 32 in the unloaded state acquired by the characteristics measurement unit 62. The calculation unit 64 also calculates the resonance resistance R in the loaded state based on the frequency characteristics of the ultrasonic transducer 32 in the loaded state acquired by the characteristics measurement unit 62. L The resonance resistance [Ω] is the real part of the impedance [Ω] at the resonance frequency fr [kHz]. The calculation unit 64 calculates the resonance resistance R0 [Ω] in the no-load state and the resonance resistance R L Based on the difference with [Ω], the acoustic conversion efficiency η is calculated.

[0031] The storage unit 66 stores a threshold value η of the acoustic conversion efficiency η, which is a criterion for determining whether the ultrasonic transducer 32 is acceptable or not. TH The threshold value η TH is input by an operator via an input device (not shown) and stored in the storage unit 66. The acoustic conversion efficiency η of a new, undeteriorated ultrasonic transducer 32 is approximately 80% to 90%. TH It is preferable that the threshold value η is set in the range of 50% to 70%, and more preferably in the range of 55% to 65%. TH is set to 60%.

[0032] The determination unit 68 determines whether or not the ultrasonic transducer 32 has deteriorated. The determination unit 68 determines whether or not the acoustic conversion efficiency η calculated by the calculation unit 64 is equal to or greater than the threshold value η stored in the storage unit 66. TH If the acoustic conversion efficiency η calculated by the calculation unit 64 is lower than the threshold value η stored in the storage unit 66, the determination unit 68 determines that the ultrasonic transducer 32 is deteriorated. TH If the value is equal to or greater than this, it is determined that the ultrasonic transducer 32 is normal.

[0033] (Method for determining deterioration of ultrasonic vibrator 32) Next, a method for determining deterioration of the ultrasonic vibrator 32 will be described. The method for determining deterioration of the ultrasonic vibrator 32 is a method for detecting deterioration of the ultrasonic vibrator 32 mounted on the processing device 10 in which the ultrasonic vibrator 32 is mounted. FIG. 3 is a flowchart showing the flow of the method for determining deterioration of the ultrasonic vibrator 32 according to the embodiment. The method for determining deterioration of the ultrasonic vibrator 32 is performed periodically when the processing device 10 is operating. The method for determining deterioration of the ultrasonic vibrator 32 includes a calculation step 1, a setting step 2, and a determination step 3.

[0034] <Calculation step 1> Calculation step 1 is a step of calculating the acoustic conversion efficiency η of the ultrasonic transducer 32. Specifically, the acoustic conversion efficiency η is calculated according to the flow shown in Fig. 4. Fig. 4 is a flowchart showing the flow of calculation step 1 shown in Fig. 3. Calculation step 1 includes a first frequency characteristic acquisition step 1-1, a first resonance resistance calculation step 1-2, a second frequency characteristic acquisition step 1-3, a second resonance resistance calculation step 1-4, and an acoustic conversion efficiency calculation step 1-5.

[0035] <First frequency characteristic acquisition step 1-1> Fig. 5 is a schematic diagram showing the first frequency characteristic acquisition step 1-1 shown in Fig. 4. The first frequency characteristic acquisition step 1-1 is a step of acquiring the frequency characteristic of the ultrasonic transducer 32 in a predetermined frequency band in an unloaded state. In the first frequency characteristic acquisition step 1-1 of the embodiment, the characteristic measurement unit 62 acquires the frequency characteristic of the ultrasonic transducer 32 in an unloaded state.

[0036] 5, in the first frequency characteristic acquisition step 1-1, with the liquid 42 not being supplied from the liquid supply unit 40 to the end face 36 of the ultrasonic generating unit 30 and the ultrasonic generating unit 30 in the air, a specific frequency signal is input from the ultrasonic oscillator 34 to ultrasonically vibrate the ultrasonic vibrator 32. At this time, the frequency [kHz] input from the ultrasonic oscillator 34 is changed and the impedance [Ω] and phase [deg] for each frequency are measured.

[0037] <First resonance resistance calculation step 1-2> 6 is a graph showing an example of the relationship between the frequency band [kHz] and the impedance [Ω] and phase [deg]. The first resonance resistance calculation step 1-2 is a step of calculating the resonance resistance R0 [Ω] in an unloaded state from the information on the frequency characteristics obtained in the first frequency characteristic acquisition step 1-1. In the first resonance resistance calculation step 1-2 of the embodiment, the calculation unit 64 calculates the resonance resistance R0 [Ω] in an unloaded state.

[0038] In the first resonant resistance calculation step 1-2, ideally, the resonant resistance is calculated at the series resonant frequency at which the conductance, which is the reciprocal of the impedance, is maximized. However, in this embodiment, taking into consideration practical ease of detection, the resonant resistance [Ω] at the resonant frequency fr [kHz] at which the phase [deg] is 0 deg is set to R0. That is, as shown in Fig. 6, the frequency at which the phase [deg] suddenly changes from -90 deg to +90 deg is set to the resonant frequency fr [kHz], and the real part of the impedance [Ω] at this resonant frequency fr [kHz] is set to the resonant resistance R0 [Ω] in the no-load state.

[0039] <Second frequency characteristic acquisition step 1-3> Fig. 7 is a schematic diagram showing the second frequency characteristic acquisition step 1-3 shown in Fig. 4. The second frequency characteristic acquisition step 1-3 is a step of acquiring the frequency characteristics of the ultrasonic transducer 32 in a predetermined frequency band in a loaded state. In the second frequency characteristic acquisition step 1-3 of the embodiment, the characteristic measurement unit 62 acquires the frequency characteristics of the ultrasonic transducer 32 in a loaded state.

[0040] 7, in the second frequency characteristic acquisition step 1-3, liquid 42 is supplied from liquid supply unit 40 to end face 36 of ultrasonic generating unit 30, and while end face 36 of ultrasonic generating unit 30 is in liquid 42, a specific frequency signal is input from ultrasonic oscillator 34 to ultrasonically vibrate ultrasonic vibrator 32. At this time, the frequency input from ultrasonic oscillator 34 is changed, and the impedance [Ω] and phase [deg] for each frequency are measured.

[0041] <Second resonance resistance calculation step 1-4> In the second resonance resistance calculation step 1-4, the resonance resistance R in the loaded state is calculated from the frequency characteristic information obtained in the second frequency characteristic acquisition step 1-3. L In the second resonance resistance calculation step 1-4 of the embodiment, the calculation unit 64 calculates the resonance resistance R L Calculate the resonant resistance R under load [Ω]. LThe method for calculating the resonant resistance R0 [Ω] is the same as the method for calculating the resonant resistance R0 [Ω] in the no-load state.

[0042] In the second resonance resistance calculation step 1-4, it is also ideal to calculate the resonance resistance at the series resonance frequency where the conductance, which is the reciprocal of the impedance, is maximized. However, in this embodiment, taking into consideration the ease of practical detection, the resonance resistance [Ω] at the resonance frequency fr [kHz] where the phase [deg] is 0 deg is calculated as R L That is, the frequency at which the phase [deg] suddenly changes from -90deg to +90deg is the resonance frequency fr [kHz], and the real part of the impedance [Ω] at this resonance frequency fr [kHz] is the resonance resistance R L Let [Ω].

[0043] <Acoustic conversion efficiency calculation steps 1-5> Step 1-5 of the acoustic conversion efficiency calculation is to calculate the resonance resistance R0 [Ω] in the unloaded state and the resonance resistance R L This is a step of calculating the acoustic conversion efficiency η based on the difference between [Ω] and [Ω]. In the acoustic conversion efficiency calculation step 1-5 of the embodiment, the calculation unit 64 calculates the acoustic conversion efficiency η.

[0044] Here, the radiation resistance [Ω], which is the change in the resonance resistance, is R r Then, the resonance resistance R0 [Ω] in the no-load state and the resonance resistance R L The relationship with [Ω] is shown by the following formula (1).

[0045]

number

[0046] The acoustic conversion efficiency η is the ratio of the output to the input, so the input is calculated by dividing the input by the resonant resistance R L [Ω], and the output is the radiation resistance R r If [Ω], it is expressed by the following formula (2).

[0047]

number

[0048] <Setting step 2> The setting step 2 is to set a threshold value η of the acoustic conversion efficiency η, which is a criterion for determining whether the ultrasonic transducer 32 is acceptable or not. TH In the setting step 2 of the embodiment, the storage unit 66 sets the threshold value η of the acoustic conversion efficiency η. TH The threshold value η TH The range of values in which is set is as described above, and therefore the explanation will be omitted.

[0049] <Judgment step 3> In the determination step 3, the acoustic conversion efficiency η calculated in the calculation step 1 is compared with the threshold value η set in the setting step 2. TH If the measured value is lower than the reference value, it is determined that the ultrasonic transducer 32 has deteriorated. In the determination step 3 of the embodiment, the determination unit 68 determines whether the ultrasonic transducer 32 has deteriorated.

[0050] 8 is a graph showing an example of the change in acoustic conversion efficiency η [%]. When the processing device 10 is operated, the ultrasonic transducer 32 deteriorates. The deterioration can be caused, for example, by peeling of the adhesive surface between the end face 36 to which the ultrasonic transducer 32 is bonded. In this case, the resonance resistance R L Since [Ω] becomes smaller and approaches the resonance resistance R0 [Ω] under no load, the acoustic conversion efficiency η [%] decreases.

[0051] 8, when the operation time has elapsed for a predetermined period of time or more, the acoustic conversion efficiency η starts to decrease. In the determination step 3, the determination unit 68 determines whether the acoustic conversion efficiency η is equal to or lower than the threshold value η TH The determining unit 68 determines whether the acoustic conversion efficiency η is below a threshold value η TH If it is determined that the value is lower than this, it is determined that the ultrasonic transducer 32 has deteriorated. In the embodiment, if the determination unit 68 determines that the ultrasonic transducer 32 has deteriorated, for example, a notification device (not shown) may issue notification information to prompt the operator to inspect or replace the transducer.

[0052] Here, in this embodiment, the basis for determining the deterioration of the ultrasonic transducer 32 based on the acoustic conversion efficiency η will be described. If the applied voltage to the ultrasonic transducer 32 is V, the output voltage is Vr, and the acoustic output is W, the output voltage Vr is expressed by the following formula (3), and the acoustic output W is expressed by the following formula (4).

[0053]

number

[0054]

number

[0055] As such, since the acoustic output W is proportional to the square of the acoustic conversion efficiency η, a small acoustic conversion efficiency η is synonymous with a small acoustic output W into the liquid. If the sound source area is S, the effective value of the sound pressure is P, the density of the liquid is ρ, the speed of sound in the liquid is c, and the specific acoustic impedance of the liquid medium is ρc, the acoustic output W can be further expressed by the following formula (5).

[0056]

number

[0057] Therefore, the following formulas (6) and (7) are derived from formulas (4) and (5).

[0058]

number

[0059]

number

[0060] This shows that the sound pressure P is proportional to the acoustic conversion efficiency η, and that the acoustic conversion efficiency η is correlated with the sound pressure P. That is, in this embodiment, determining the deterioration of the ultrasonic transducer 32 based on the acoustic conversion efficiency η is synonymous with determining the deterioration of the ultrasonic transducer 32 based on the sound pressure P.

[0061] [Modification] Next, the configuration of a processing device 12 according to a modified example of the present invention will be described. Fig. 9 is a schematic diagram showing a first frequency characteristic acquisition step 1-1 performed by the processing device 12 according to the modified example. Fig. 10 is a schematic diagram showing a second frequency characteristic acquisition step 1-3 performed by the processing device 12 according to the modified example. In the processing device 12 shown in Figs. 9 and 10, the same components as those in the processing device 10 of the embodiment shown in Figs. 1 and 2 are designated by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0062] In a modified example, the processing device 12 is a cleaning device that cleans an object by propagating ultrasonic waves 38 into a liquid 72 such as water or a cleaning liquid. The processing device 12 includes a liquid tank 70, an ultrasonic wave generating unit 30-2, and a controller 60.

[0063] The liquid tank 70 is a tank that stores a liquid 72 such as water or a cleaning liquid. The liquid tank 70 may contain a mesh-like base on which an object to be cleaned is placed.

[0064] The ultrasonic wave generating unit 30-2 is a unit that applies ultrasonic waves 38 to an object to be cleaned immersed in a liquid 72 in a liquid tank 70, thereby removing dirt adhering to the object to be cleaned and cleaning the object. The ultrasonic wave generating unit 30-2 includes an ultrasonic vibrator 32-2 and an ultrasonic oscillator 34.

[0065] The basic configuration of the ultrasonic vibrator 32-2 itself is similar to that of the ultrasonic vibrator 32 of the embodiment. The ultrasonic vibrator 32-2 of the modified example has an end face 36 facing upward and is fixed to the bottom surface of the liquid tank 70. The configurations of the ultrasonic oscillator 34 and the controller 60 are similar to those of the embodiment, and therefore description thereof will be omitted.

[0066] 9, when the first frequency characteristic acquisition step 1-1 is performed in the processing device 12 of the modified example, a specific frequency signal is input from the ultrasonic oscillator 34 to ultrasonically vibrate the ultrasonic vibrator 32 in a state where no liquid 72 is placed in the liquid tank 70. At this time, the frequency [kHz] input from the ultrasonic oscillator 34 is changed, and the impedance [Ω] and phase [deg] of each frequency are measured.

[0067] 10, when the second frequency characteristic acquisition step 1-3 is performed in the processing device 12 of the modified example, a specific frequency signal is input from the ultrasonic oscillator 34 to ultrasonically vibrate the ultrasonic vibrator 32 while the liquid 72 is placed in the liquid tank 70. At this time, the frequency [kHz] input from the ultrasonic oscillator 34 is changed, and the impedance [Ω] and phase [deg] of each frequency are measured.

[0068] As described above, the deterioration determination method for ultrasonic transducers 32, 32-2 and the processing devices 10, 12 according to the embodiment and the modified example determine the deterioration of the ultrasonic transducers 32, 32-2 based on the acoustic conversion efficiency η. Specifically, the frequency characteristics of the ultrasonic transducers 32, 32-2 under load and under no load are acquired, and the acoustic conversion efficiency η is calculated from the change in impedance [Ω] at each resonance frequency fr [kHz], i.e., the resonance resistance [Ω], to estimate the amount of energy of the sound pressure P in the liquid. This makes it possible to reliably and simply measure changes in the characteristics of the ultrasonic transducers 32, 32-2.

[0069] The present invention is not limited to the above-described embodiment and modifications. In other words, various modifications can be made without departing from the gist of the present invention. For example, the processing devices 10 and 12 are not limited to the stripping device of the embodiment or the cleaning device of the modifications, and may be any device that utilizes output into a liquid, such as an ultrasonic nozzle or ultrasonic horn.

[0070] Furthermore, among the processes described in the above embodiment and modified examples, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically using a known method. Furthermore, the above-described controller 60 may be configured by multiple computers each having several separate functions, or may exist separately via a network, and some of the computer functions may be provided by a cloud server that executes various functions in the form of cloud computing. Furthermore, a program may be distributed to the controller 60 via a network. Furthermore, the controller 60, input device, display device, alarm device, etc. may be built into the ultrasonic oscillator 34, and the operator's operations may be performed directly from the ultrasonic oscillator 34. [Explanation of symbols]

[0071] 10, 12 Processing equipment 20 Holding table 30, 30-2 Ultrasonic generating unit 32, 32-2 Ultrasonic transducer 34 Ultrasonic oscillator 40 Liquid Supply Unit 50 Peeling Unit 60 Controller 62 Characteristics measurement section 64 Calculation Unit 66 Memory section 68 Judgment section 70 Liquid tank 90 ingots 92 First Side 94 Second Side 96 Peeling layer 98 wafers

Claims

1. 1. A method for determining deterioration of an ultrasonic vibrator in a processing apparatus equipped with an ultrasonic vibrator, the method comprising: a calculation step of calculating the acoustic conversion efficiency of the ultrasonic transducer; a setting step of setting a threshold value of the acoustic conversion efficiency as a criterion for determining whether the ultrasonic transducer is acceptable or not; a determining step of determining that the ultrasonic transducer is deteriorated when the acoustic conversion efficiency calculated in the calculating step is lower than the threshold value set in the setting step; Equipped with A method for determining deterioration of an ultrasonic transducer, comprising:

2. The calculation step includes: a first frequency characteristic acquisition step of acquiring the frequency characteristics of the ultrasonic transducer in a predetermined frequency band in an unloaded state; a first resonance resistance calculation step of calculating the resonance resistance in the no-load state from information on the frequency characteristics obtained in the first frequency characteristic acquisition step; a second frequency characteristic acquisition step of acquiring the frequency characteristics of the ultrasonic transducer in a predetermined frequency band under a load; a second resonance resistance calculation step of calculating a resonance resistance in the loaded state from information on the frequency characteristics obtained in the second frequency characteristic acquisition step; an acoustic conversion efficiency calculation step of calculating the acoustic conversion efficiency based on a difference between the resonance resistance in the unloaded state and the resonance resistance in the loaded state; Contains 2. The method for determining deterioration of an ultrasonic vibrator according to claim 1.

3. A processing device equipped with an ultrasonic vibrator, an ultrasonic wave generating unit having the ultrasonic vibrator and an ultrasonic oscillator that inputs a specific frequency signal to the ultrasonic vibrator; a controller for controlling the ultrasonic generating unit; Equipped with The controller A calculation unit that calculates the acoustic conversion efficiency of the ultrasonic transducer; a storage unit that stores a threshold value of the acoustic conversion efficiency that serves as a criterion for determining whether the ultrasonic transducer is acceptable or not; a determination unit that determines that the ultrasonic transducer is deteriorated when the acoustic conversion efficiency calculated by the calculation unit is lower than the threshold value stored in the storage unit; and have A processing device characterized by:

4. The controller Further, a characteristic measuring unit is provided to acquire the frequency characteristics of the ultrasonic transducer in a predetermined frequency band, The calculation unit Calculating the resonance resistance in the no-load state based on the frequency characteristics of the ultrasonic transducer in the no-load state acquired by the characteristics measurement unit; Calculating the resonance resistance in the loaded state based on the frequency characteristics of the ultrasonic transducer in the loaded state acquired by the characteristics measurement unit; The acoustic conversion efficiency is calculated based on the difference between the resonance resistance in the unloaded state and the resonance resistance in the loaded state.

4. The processing device according to claim 3.

5. The processing device comprises: a holding table for holding an ingot on which a peeled layer has been formed to a depth corresponding to the thickness of a wafer to be manufactured by irradiating the ingot with a laser beam; the ultrasonic wave generating unit applying ultrasonic waves to the ingot; a liquid supply unit that supplies liquid between the ultrasonic generating unit and the ingot; a separation unit that holds the wafer to be manufactured and moves it in a direction away from the ingot to separate the wafer to be manufactured from the ingot; A peeling device comprising: The processing device according to claim 3 or 4.

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