Ultrasonic measuring jig and method for measuring ultrasonic vibration

Abstract

To provide an ultrasonic measuring jig and a method for measuring ultrasonic vibration, which can accurately and easily detect abnormalities in an ultrasonic application mechanism for improving the peelability of a wafer from an ingot.SOLUTION: An ultrasonic measuring jig 1 measures ultrasonic vibrations, and includes: a plate-shaped member 10; a columnar member 20 having a recess 22 formed in one surface 21, the one surface 21 facing and being attached to one surface 11 of the plate-shaped member 10; a piezoelectric element 30 attached to the one surface 11 of the plate-shaped member 10 and housed in the recess 22; and an output portion 40 for outputting vibration data detected by the piezoelectric element 30 to the outside.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ultrasonic measurement tool and a method for measuring ultrasonic vibration. [Background technology]

[0002] Wafers such as semiconductor wafers on which devices are formed are generally produced by thinly slicing cylindrical ingots with a wire saw and polishing the front and back surfaces. However, cutting with a wire saw has the problem that most of the ingot is discarded, making it uneconomical.

[0003] To solve this problem, an apparatus has been proposed that produces wafers from ingots by repeating the steps of irradiating an ingot with a laser beam to form a peeling layer, peeling the wafer from the peeling layer, and then grinding and flattening the peeled surface (see Patent Document 1). Also, a technology has been disclosed that improves peelability by applying ultrasonic waves when peeling the wafer from the peeling layer (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-012765 A [Patent Document 2] JP 2019-102513 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned apparatus and method, there are cases where the wafer cannot be peeled off properly due to malfunctions of the laser irradiation mechanism, ultrasonic wave applying mechanism, etc. Among them, there is a method for detecting abnormalities in the ultrasonic wave applying mechanism by measuring the sound pressure using a commercially available sound pressure meter, but there is a problem that accurate measurement is difficult because the vibrations that the workpiece actually receives are different from the vibrations that the sound pressure meter can detect. Therefore, there is a problem that not only does it take time to identify the malfunction, but it is necessary to prepare an extra actual workpiece for abnormality detection, which increases costs.

[0006] The present invention has been made in consideration of such problems, and its object is to provide an ultrasonic measurement tool and a method for measuring ultrasonic vibrations that can accurately and easily detect abnormalities in an ultrasonic application mechanism for improving the peelability of a wafer from an ingot. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the ultrasonic measuring jig of the present invention is an ultrasonic measuring jig for measuring ultrasonic vibrations, and is characterized in comprising a plate-shaped member, a columnar member having a recess formed on one surface and attached to one surface of the plate-shaped member with the recess facing the one surface, a piezoelectric element attached to the one surface of the plate-shaped member and housed in the recess, and an output section for outputting vibration data detected by the piezoelectric element to the outside.

[0008] In addition, the ultrasonic measurement tool of the present invention is characterized in that it further comprises a second piezoelectric element attached to one surface of the plate-shaped member and housed in the recess, a battery connected by wire to the second piezoelectric element and supplying power to the output section, and a power generating and charging circuit section that converts vibrations of the second piezoelectric element into electricity and supplies the electricity to the battery.

[0009] In addition, the ultrasonic measuring tool of the present invention is characterized by further comprising a battery that is connected to the piezoelectric element by wire and supplies power to the output unit, and a power generating and charging circuit unit that converts the vibration of the piezoelectric element into electricity and supplies it to the battery.

[0010] In addition, the ultrasonic vibration measuring method of the present invention is characterized by including a jig preparation step of preparing an ultrasonic measurement jig, an ultrasonic application step of applying ultrasonic waves to the ultrasonic measurement jig by placing an ultrasonic application unit facing the other side of the plate-shaped member and operating the ultrasonic application unit while supplying liquid between the ultrasonic application unit and the other side of the plate-shaped member, and a measurement step of measuring the vibration received by the plate-shaped member based on vibration data detected by the piezoelectric element during the ultrasonic application step.

[0011] In addition, the ultrasonic vibration measuring method of the present invention preferably further includes a workpiece preparation step of preparing a workpiece having a peeling layer formed therein, the peeling layer including a modified portion and a crack extending from the modified portion, by irradiation with a laser beam; a confirmation step of confirming whether the workpiece can be normally separated starting from the peeling layer by applying ultrasonic waves to the workpiece using the ultrasonic application unit; and after confirming that the workpiece can be normally separated in the confirmation step, a reference data acquisition step of measuring the vibration received by the plate-like member based on the vibration data detected by the piezoelectric element while applying ultrasonic waves to the ultrasonic measurement jig using the ultrasonic application unit; and a determination step of comparing the results obtained by the reference data acquisition step with the results obtained by the measurement step to determine whether the ultrasonic application unit is operating normally. Effect of the Invention

[0012] The present invention can accurately and easily detect an abnormality in an ultrasonic wave applying mechanism for improving the peelability of a wafer from an ingot. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an exploded perspective view of an ultrasonic measurement tool according to an embodiment. [Diagram 2]FIG. 2 is a cross-sectional view that diagrammatically illustrates the ultrasonic measurement tool shown in FIG. [Diagram 3] FIG. 3 is a diagram showing the electric circuit configuration of the ultrasonic measuring tool shown in FIG. [Figure 4] FIG. 4 is a flowchart showing the flow of the ultrasonic measurement method according to the embodiment. [Diagram 5] FIG. 5 is a perspective view showing one state of the workpiece preparing step shown in FIG. [Figure 6] FIG. 6 is a side view of the workpiece shown in FIG. [Figure 7] FIG. 7 is a side view, partly in section, showing a state subsequent to FIGS. 5 and 6. FIG. [Figure 8] FIG. 8 is a perspective view showing a state subsequent to FIG. [Figure 9] FIG. 9 is a side view showing one state of the checking step shown in FIG. [Figure 10] FIG. 10 is a side view showing a state subsequent to FIG. [Figure 11] FIG. 11 is a side view showing a state subsequent to that shown in FIG. [Figure 12] FIG. 12 is a side view, partially in section, showing one state of the reference data obtaining step shown in FIG. [Figure 13] FIG. 13 is a cross-sectional view that illustrates the behavior of the plate-like member in FIG. [Figure 14] FIG. 14 is a cross-sectional view that illustrates an ultrasonic measurement tool according to a first modified example. [Figure 15] FIG. 15 is a cross-sectional view that illustrates an ultrasonic measurement tool according to a second modified example. [Figure 16] FIG. 16 is a diagram showing the electric circuit configuration of an ultrasonic measurement tool according to the second modified example. [Figure 17] FIG. 17 is a cross-sectional view that illustrates an ultrasonic measurement tool according to a third modified example. [Figure 18] FIG. 18 is a diagram showing the electric circuit configuration of an ultrasonic measurement tool according to the third modified example. [Figure 19] FIG. 19 is a graph showing an example of vibration data detected by the piezoelectric element according to the third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The form (embodiment) 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 embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0015] [Embodiment] <Ultrasonic measuring tool 1> The configuration of an ultrasonic measurement tool 1 according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an exploded perspective view of the ultrasonic measurement tool 1 according to the embodiment. Fig. 2 is a cross-sectional view that typically shows the ultrasonic measurement tool 1 shown in Fig. 1. Fig. 3 is a diagram showing the electrical circuit configuration of the ultrasonic measurement tool 1 shown in Fig. 1.

[0016] The ultrasonic measurement jig 1 is a jig for measuring ultrasonic vibration. More specifically, the ultrasonic measurement jig 1 is a jig that reproduces an ingot 110 and a wafer 130 to which ultrasonic waves are applied in order to improve peelability when peeling the wafer 130 from the ingot 110 shown in Figs. 5 to 11 described later. As shown in Figs. 1 to 3, the ultrasonic measurement jig 1 has a plate-shaped member 10, a columnar member 20, a piezoelectric element 30, an output section 40, an averaging circuit section 50, and a battery 70.

[0017] The plate-like member 10 is a member formed into a plate shape with a uniform thickness as a whole, and is a pseudo wafer that can be likened to the wafer 130 shown in Figs. 9 to 11 described later. The plate-like member 10 of the embodiment is a disk shape with an outer diameter of 4 inches and a thickness of 600 μm, but the plate-like member 10 of the present invention is not particularly limited in size and planar shape, and may be, for example, a square, rectangular, polygonal, or other plate shape in planar shape. The plate-like member 10 of the embodiment is made of sapphire (Al2O3). The plate-like member 10 of the present invention is not limited to sapphire, and may be, for example, SUS303 or SUS304, or may be made of other materials as long as the present invention can be implemented.

[0018] The columnar member 20 is a member formed into a columnar shape with a uniform height as a whole, and is a pseudo ingot that is likened to the ingot 110 shown in Figs. 5 to 11 described later. The columnar member 20 in the embodiment has an outer diameter of 4 inches and a thickness of 200 mm, but the columnar member 20 of the present invention is not particularly limited in size and planar shape, and may be, for example, a columnar shape with a square, rectangular, polygonal, or other planar shape. Note that the plate-like member 10 and the columnar member 20 have the same diameter and planar shape in the embodiment, but are not limited to the same diameter or shape in the present invention. The columnar member 20 of the embodiment is made of glass. Examples of glass include alkali glass, non-alkali glass, soda-lime glass, lead glass, borosilicate glass, quartz glass, and the like. The plate-like member 10 of the present invention is not limited to glass, and may be, for example, PEEK or PP, or may be made of other materials as long as the present invention can be implemented.

[0019] A recess 22 is formed in the center of one surface 11 of the columnar member 20. The recess 22 is formed to be deeper than the thickness of at least the piezoelectric element 30. An output section 40, an averaging circuit section 50, an A / D conversion section 60, and a battery 70 are disposed on a bottom surface 23 of the recess 22.

[0020] One surface 11 of the plate-like member 10 and one surface 21 of the columnar member 20 are bonded together facing each other. When the plate-like member 10 and the columnar member 20 are bonded together, the other surface 12, which is the surface opposite to the one surface 11 of the plate-like member 10, and the other surface 24, which is the surface opposite to the one surface 21 of the columnar member 20, are both exposed, and the recess 22 forms a closed space.

[0021] The piezoelectric element 30 is a passive element that converts an applied pressure into a voltage, and includes a piezoelectric body and two electrodes sandwiching the piezoelectric body. The piezoelectric element 30 is attached to the center of one surface 11 of the plate-like member 10. The piezoelectric element 30 is housed in the recess 22 of the columnar member 20 in a state in which the one surface 11 of the plate-like member 10 and one surface 21 of the columnar member 20 are attached to each other. The piezoelectric element 30 of the embodiment has an outer diameter of 30 mm and a thickness of 250 μm.

[0022] In the embodiment, the piezoelectric element 30 detects the applied ultrasonic vibration and converts it into a voltage. More specifically, the piezoelectric element 30 converts the pressure into a voltage by utilizing the phenomenon of the piezoelectric effect, in which when pressure is applied to the plate-like member 10 and the piezoelectric element 30 bend in the thickness direction, one side of the piezoelectric element 30 contracts and the other side expands, resulting in polarization proportional to the pressure. When ultrasonic vibration is applied, the expansion and contraction of one side and the other side of the piezoelectric element 30 are periodically reversed, generating an AC signal. In this way, the piezoelectric element 30 converts the detected vibration data into a voltage value.

[0023] The output unit 40 outputs the vibration data detected by the piezoelectric element 30 to the outside. The outside is an external device separate from the ultrasonic measurement tool 1, and in this embodiment, is a computer 80. In this embodiment, the output unit 40 includes a transmission unit that transmits the vibration data detected by the piezoelectric element 30 to the outside by wireless communication. In this embodiment, the transmission unit is assumed to be a Bluetooth (registered trademark) module, but may be realized by a communication module using other short-range wireless communication such as a wireless LAN (Local Area Network) or a wireless communication network such as LTE (Long Term Evolution), 4G (4th Generation), or 5G (5th Generation: fifth generation mobile communication system).

[0024] The averaging circuit unit 50 averages the vibration data of the AC signal generated in the piezoelectric element 30. The averaging circuit unit 50 includes an absolute value circuit 51 and a smoothing circuit 52. In the absolute value circuit 51, the voltage value of the AC signal generated in the piezoelectric element 30 is converted into an absolute value. In the absolute value circuit 51, for example, as shown in FIG. 3, when a sine wave is input, a pulsating signal having a full-wave rectified waveform that converts the negative voltage of the input voltage into a positive voltage is output. In the smoothing circuit 52, the voltage value of the pulsating signal converted into an absolute value in the absolute value circuit 51 is converted into a smoothed DC signal. Thus, in the embodiment, the vibration data of the AC signal generated in the piezoelectric element 30 is averaged and converted into a DC signal by the averaging circuit unit 50, and then output to the output unit 40. That is, information indicating the magnitude of the amplitude of the AC voltage generated in the piezoelectric element 30 is output to the output unit 40.

[0025] The output section 40 of the embodiment further includes an A / D conversion section 60. The A / D conversion section 60 converts an analog signal into a digital signal. In the output section 40, the vibration data detected by the piezoelectric element 30 and averaged in the averaging circuit section 50 is converted into a digital signal in the A / D conversion section 60, and transmitted to the outside by wireless communication via a transmission unit. A battery 70 supplies power to the transmission unit. The vibration data transmitted from the transmission unit is received by a computer 80, which is an external device.

[0026] Computer 80 is a well-known computer that includes a processing device as a computing 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.

[0027] <Ultrasonic measurement method> 4 is a flowchart showing the flow of an ultrasonic measurement method according to an embodiment. The ultrasonic measurement method according to the embodiment includes a workpiece preparation step 101, a confirmation step 102, a jig preparation step 103, a reference data acquisition step 104, an ultrasonic wave application step 105, a measurement step 106, and a judgment step 107. The workpiece preparation step 101, the confirmation step 102, the jig preparation step 103, and the reference data acquisition step 104 are preparatory steps carried out in advance before producing wafers 130 one after another from a workpiece (ingot 110). The ultrasonic wave application step 105, the measurement step 106, and the judgment step 107 are inspection steps that are appropriately and repeatedly carried out during processing of the workpiece.

[0028] (Workpiece preparation step 101) Fig. 5 is a perspective view showing one state of the workpiece preparation step 101 shown in Fig. 4. Fig. 6 is a side view of the workpiece shown in Fig. 5. Fig. 7 is a side view, partially in cross section, showing one state after Figs. 5 and 6. Fig. 8 is a perspective view showing one state after Fig. 7. The workpiece preparation step 101 is a step of preparing a workpiece on which a peeling layer 123 serving as a starting point for peeling off the wafer 130 from the workpiece is formed.

[0029] The workpiece is an ingot 110 such as a single crystal semiconductor ingot formed in a columnar shape as a whole and made of sapphire, silicon (Si), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), lithium tantalate (LiTaO3), or the like. In the embodiment, the ingot 110 is cylindrical. The ingot 110 has a first surface 111, a second surface 112, a peripheral surface 113, a first orientation flat 114, and a second orientation flat 115.

[0030] The first surface 111 is circular in the embodiment and is one end surface of the ingot 110 formed in a cylindrical shape. The second surface 112 is circular in the embodiment and is an end surface of the ingot 110 opposite to the first surface 111, which is formed in a cylindrical shape. The second surface 112 corresponds to the bottom surface of the ingot 110. The peripheral surface 113 is a surface continuing to the outer edge of the first surface 111 and the outer edge of the second surface 112.

[0031] The first orientation flat 114 is a plane formed on a part of the peripheral surface 113 to indicate the crystal orientation of the ingot 110. The second orientation flat 115 is a plane formed on a part of the peripheral surface 113 to indicate the crystal orientation of the ingot 110. The second orientation flat 115 is perpendicular to the first orientation flat 114. The length of the first orientation flat 114 is longer than the length of the second orientation flat 115.

[0032] The ingot 110 also has a c-axis 118 inclined at an off angle 120 in an inclination direction 117 toward the second orientation flat 115 with respect to a perpendicular line 116 to the first surface 111, and a c-plane 119 perpendicular to the c-axis 118. The inclination direction 117 of the c-axis 118 from the perpendicular line 116 is perpendicular to the extension direction of the second orientation flat 115 and is parallel to the first orientation flat 114. The c-plane 119 is inclined at the off angle 120 with respect to the first surface 111 of the ingot 110.

[0033] An infinite number of c-planes 119 are set in the ingot 110 at the molecular level of the ingot 110. In the embodiment, the ingot 110 has an off-angle 120 set to 1°, 4°, or 6°, but in the present invention, the ingot 110 may be manufactured with the off-angle freely set within the range of, for example, 1° to 6°. After the first surface 111 of the ingot 110 is ground by a grinding device, the ingot 110 is polished by a polishing device to form the first surface 111 into a mirror surface.

[0034] In the workpiece preparation step 101, a peeling layer 123 including a modified portion 121 and a crack 122 extending from the modified portion 121 is formed inside the ingot 110 by irradiation with a laser beam 222. In the workpiece preparation step 101 of the embodiment, the irradiation of the laser beam 222 is performed by a laser processing apparatus 200 shown in FIG.

[0035] The laser processing apparatus 200 includes a holding table 210, a laser beam irradiation unit 220, and a moving unit (not shown) that moves the holding table 210 and the laser beam irradiation unit 220 relatively. The holding table 210 holds the ingot 110 on a holding surface 211. The holding surface 211 has a disk shape made of porous ceramics or the like, and is connected to a vacuum suction source via a vacuum suction path, for example. The holding table 210 suction-holds the second surface 112 side of the ingot 110 placed on the holding surface 211.

[0036] The laser beam irradiation unit 220 has, for example, an oscillator that emits a laser beam 222, a collector 221 that collects the laser beam 222 toward the ingot 110 held on the holding table 210, and various optical components that guide the laser beam 222 from the oscillator to the collector 221. In the following description, the X-axis direction, which is one direction on a horizontal plane, is the processing feed direction, and the Y-axis direction, which is a direction perpendicular to the X-axis direction on the horizontal plane, is the indexing feed direction.

[0037] In the workpiece preparation step 101, the second surface 112 side of the ingot 110 is sucked and held on the holding surface 211 of the holding table 210. At this time, the second orientation flat 115 of the ingot 110 is adjusted to be parallel to the processing feed direction (X-axis direction). Next, the focusing point 223 of the laser beam 222 is positioned at a depth inside the ingot 110 corresponding to the thickness of the wafer 130 (see FIGS. 9 to 11) to be produced. The laser beam 222 is a pulsed laser beam with a wavelength that is transparent to the ingot 110.

[0038] In the workpiece preparation step 101, next, the condenser 221 of the laser beam irradiation unit 220 and the holding table 210 are moved relatively in a state where the focal point 223 is positioned at a depth corresponding to the thickness of the wafer 130 (see FIG. 7, etc.) to be produced from the first surface 111 side inside the ingot 110. That is, the laser beam 222 is irradiated toward the ingot 110 while the focal point 223 and the ingot 110 are moved relatively in a direction parallel to the first surface 111 (XY direction).

[0039] By irradiating the ingot 110 with the pulsed laser beam 222, a modified region 121 is formed inside the ingot 110 along the processing feed direction. Here, the modified region 121 means a region in which the density, refractive index, mechanical strength or other physical properties are made different from those of the surrounding area by irradiating the ingot 110 with the laser beam 222. The modified region 121 is, for example, a melting process region, a crack region, a dielectric breakdown region, a refractive index change region, a region where these regions are mixed, or the like. The modified region 121 has a lower mechanical strength, etc. than other parts of the ingot 110.

[0040] Inside the ingot 110, a crack 122 is generated that extends from the modified portion 121 along the c-plane 119. That is, in the embodiment, the crack 122 extends in the indexing feed direction (Y-axis direction). In this manner, in the workpiece preparation step 101, a workpiece (ingot 110) is prepared in which a peeling layer 123 including the modified portion 121 and the crack 122 formed from the modified portion 121 along the c-plane 119 is formed.

[0041] (Confirmation step 102) Fig. 9 is a side view showing one state of the confirmation step 102 shown in Fig. 4. Fig. 10 is a side view showing one state after Fig. 9. Fig. 11 is a side view showing one state after Fig. 10. The confirmation step 102 is a step of confirming whether or not the workpiece (ingot 110) can be normally separated starting from the peeling layer 123 by applying ultrasonic waves to the workpiece (ingot 110) using the ultrasonic application unit 320.

[0042] In the confirmation step 102 of the embodiment, the application of ultrasonic waves is performed by an ultrasonic application device 300 shown in Fig. 9. Also, in the confirmation step 102 of the embodiment, the separation starting from the peeling layer 123 is performed by a peeling device 400 shown in Figs. 10 and 11.

[0043] The ultrasonic wave applying device 300 shown in Fig. 9 includes a holding table 310, an ultrasonic wave applying unit 320, a moving unit (not shown) that relatively moves the holding table 310 and the ultrasonic wave applying unit 320, and a liquid supply unit 330. The holding table 310 holds the ingot 110 on a holding surface 311. The holding surface 311 has a disk shape made of porous ceramics or the like, and is connected to a vacuum suction source via a vacuum suction path, for example. The holding table 310 suctions and holds the second surface 112 side of the ingot 110 placed on the holding surface 311. The holding table 310 may also be used as the holding table 210 of the laser processing device 200.

[0044] The ultrasonic wave application unit 320 includes, for example, an ultrasonic transducer that expands and contracts when AC power is applied to generate ultrasonic vibrations in a direction perpendicular to one end face 321 facing the holding surface 311 of the holding table 310, a power source that applies AC power to the ultrasonic transducer, and a liquid supply unit 330. The end face 321 is a flat surface parallel to the horizontal direction, and vibrates in a direction perpendicular to the holding surface 311 of the holding table 310 in response to ultrasonic vibrations of the ultrasonic transducer.

[0045] 10 and 11 includes an ingot holding unit 410, a wafer holding unit 420, and a moving unit (not shown) that relatively moves the ingot holding unit 410 and the wafer holding unit 420. The ingot holding unit 410 suction-holds the second surface 112 side of the ingot 110 placed on a holding surface 411.

[0046] The wafer holding unit 420 has a holding surface 421 for suction-holding the first surface 111 side of the ingot 110, i.e., the wafer 130 to be produced, and is capable of suction-holding the first surface 111 side of the ingot 110 that is in contact with the holding surface 421. The holding surfaces 411, 421 are disk-shaped and made of porous ceramics or the like, and are connected to a vacuum suction source via, for example, a vacuum suction path. The ingot holding unit 410 may also serve as the holding table 310 of the ultrasonic wave applying device 300.

[0047] 9, in the confirmation step 102, first, the second surface 112 of the ingot 110 on which the peeling layer 123 is formed is held by the holding surface 311 of the holding table 310. Next, the end surface 321 of the ultrasonic wave application unit 320 is made to face the first surface 111 of the ingot 110 held on the holding table 310 with a predetermined interval therebetween. The predetermined interval is, for example, about 0.5 to 1.0 mm.

[0048] In the confirmation step 102, next, liquid 331 is supplied from liquid supply unit 330 between first surface 111 of ingot 110 and end surface 321 of ultrasonic wave applying unit 320. Liquid 331 is, for example, pure water. Next, while end surface 321 of ultrasonic wave applying unit 320 is immersed in liquid 331, AC power is applied to the ultrasonic vibrator of ultrasonic wave applying unit 320 for a predetermined time to ultrasonically vibrate end surface 321.

[0049] As a result, when the ultrasonic vibration of the end face 321 is applied to the first surface 111 of the ingot 110 via the liquid 331, the crack 122 extends. In the confirmation step 102, the ultrasonic application unit 320 and the first surface 111 of the ingot 110 are moved relatively to apply ultrasonic waves to the entire surface of the first surface 111 of the ingot 110, thereby extending the crack 122 in the entire peeling layer 123.

[0050] 10 , in the confirmation step 102, the second surface 112 of the ingot 110 is then held by the holding surface 411 of the ingot holding unit 410. Next, the wafer holding unit 420 is brought close to the ingot holding unit 410, and the first surface 111 of the ingot 110 is suction-held by the holding surface 421.

[0051] 11 , the wafer holding unit 420 is then separated from the ingot holding unit 410. As a result, the ingot 110 pulled vertically is separated from the peeled layer 123 as a starting point, and a peeled portion of the ingot 110 on the first surface 111 side is generated as a wafer 130.

[0052] In addition, the wafer 130 may be completely separated from the ingot 110 with the peeling layer 123 as an interface at the stage where ultrasonic waves are applied in the confirmation step 102, or may not be completely separated. In the latter case, the wafer 130 is pulled upward by the wafer holding unit 420 relative to the ingot 110 held by the ingot holding unit 410, whereby the wafer 130 is peeled and separated from the ingot 110 with the peeling layer 123 as a starting point.

[0053] In the confirmation step 102, if the wafer 130 cannot be peeled off by the peeling device 400, or if the wafer 130 cannot be normally separated due to cracks or chips, the processing conditions or various devices are changed, and the process is started again from the workpiece preparation step 101. Whether or not the separation was normal may be confirmed by visual inspection by an operator, or may be automatically confirmed by performing well-known image processing on an image captured by an imaging means (not shown).

[0054] (Jig preparation step 103) The jig preparation step 103 is a step of preparing the ultrasonic measurement jig 1. Note that the jig preparation step 103 may be performed at any time before the reference data acquisition step 104.

[0055] (Reference data acquisition step 104) Fig. 12 is a side view, partially in cross section, showing one state of the reference data acquisition step 104 shown in Fig. 4. Fig. 13 is a cross-sectional view showing a schematic behavior of the plate-like member 10 in Fig. 12. The reference data acquisition step 104 is carried out before the ultrasonic wave application step 105, the measurement step 106, and the judgment step 107, which will be described later, after it has been confirmed in the confirmation step 102 that the workpiece (ingot 110) can be normally separated.

[0056] The reference data acquisition step 104 is a step of measuring the vibration received by the plate-like member 10 based on the vibration data detected by the piezoelectric element 30 while applying ultrasonic waves to the ultrasonic measurement jig 1 using the ultrasonic application unit 320 used in the confirmation step 102. In other words, ultrasonic waves are applied to the ultrasonic measurement jig 1, which is a dummy ingot and a dummy wafer, under the same conditions as those for applying ultrasonic waves to the workpiece (ingot 110) in the confirmation step 102.

[0057] 12, in the reference data acquisition step 104, first, the surface (other surface 24) of the ultrasonic measurement tool 1 on the columnar member 20 side is held by the holding surface 311 of the holding table 310. Next, the end surface 321 of the ultrasonic application unit 320 is made to face the surface (other surface 12) of the ultrasonic measurement tool 1 on the plate-like member 10 side held by the holding table 310 with a predetermined interval therebetween. The predetermined interval is the same as the distance between the first surface 111 of the ingot 110 and the end surface 321 of the ultrasonic application unit 320 when ultrasonic waves are applied to the ingot 110 in the confirmation step 102.

[0058] In the reference data acquisition step 104, next, liquid 331 is supplied from the liquid supply unit 330 between the other surface 12 of the plate-like member 10 and the end surface 321 of the ultrasonic wave applying unit 320. Next, while the end surface 321 of the ultrasonic wave applying unit 320 is immersed in the liquid 331, AC power is applied to the ultrasonic vibrator of the ultrasonic wave applying unit 320 for a predetermined time to ultrasonically vibrate the end surface 321.

[0059] As a result, when the ultrasonic vibration of the end face 321 is applied to the face (the other face 12) of the ultrasonic measurement tool 1 on the plate-like member 10 side via the liquid 331, the plate-like member 10 and the piezoelectric element 30 attached to one face 11 of the plate-like member 10 flexurally vibrate in the thickness direction, as shown in FIG. 13.

[0060] When the piezoelectric element 30 bends in the thickness direction, a voltage corresponding to the pressure that bends it in the thickness direction is generated, and an AC signal having an amplitude of a voltage value corresponding to the pressure in response to the flexural vibration is generated. That is, the piezoelectric element 30 can measure the vibration received by the plate-like member 10 by detecting the vibration data of the ultrasonic vibration as a voltage. The vibration data is averaged by the averaging circuit section 50 and converted into a DC signal, and then output from the output section 40 to the computer 80. The computer 80 stores the measured vibration data as reference data.

[0061] As described above, the vibration data of ultrasonic vibrations during ultrasonic application when peeling wafer 130 from ingot 110 in an apparatus operating normally is obtained as reference data through workpiece preparation step 101, confirmation step 102, jig preparation step 103, and reference data acquisition step 104. The subsequent ultrasonic application step 105, measurement step 106, and judgment step 107 are performed to check whether ultrasonic application unit 320 is normal or not while wafers 130 are being produced one after another from ingot 110 on an actual production line.

[0062] (Ultrasonic application step 105 and measurement step 106) The ultrasonic wave applying step 105 is a step of placing an ultrasonic wave applying unit 320 (see FIG. 12) facing the other surface 12 of the plate-like member 10 of the ultrasonic measurement tool 1 (see FIG. 12) and operating the ultrasonic wave applying unit 320 while supplying liquid 331 between the ultrasonic wave applying unit 320 and the other surface 12 of the plate-like member 10, thereby applying ultrasonic waves to the ultrasonic measurement tool 1. The measuring step 106 is a step of measuring the vibration received by the plate-like member 10 based on the vibration data detected by the piezoelectric element 30 during the ultrasonic wave applying step 105.

[0063] The ultrasonic wave applying step 105 and the measurement step 106 are performed in the same procedure as the reference data obtained in the reference data obtaining step 104. For example, if the ultrasonic wave applying unit 320 is operating normally and ultrasonic waves are applied to the ultrasonic measurement jig 1 under the same conditions as in the reference data obtaining step 104, vibration data similar to the reference data obtained in the reference data obtaining step 104 is obtained. Also, for example, if the ultrasonic wave applying unit 320 has a malfunction and ultrasonic waves cannot be applied to the ultrasonic measurement jig 1 under the same conditions as in the reference data obtaining step 104, vibration data different from the reference data obtained in the reference data obtaining step 104 is obtained.

[0064] (Decision step 107) In the determination step 107, it is determined whether the ultrasonic wave applying unit 320 is operating normally by comparing the result acquired in the reference data acquisition step 104 with the result acquired in the measurement step 106. In the determination step 107, for example, if the result acquired in the measurement step 106 exceeds a predetermined threshold value set based on the result acquired in the reference data acquisition step 104, it may be determined that the ultrasonic wave applying unit 320 has a defect.

[0065] In the embodiment, the determination step 107 is executed by the computer 80. The computer 80 outputs the determination result to a display device (not shown) or the like. When the computer 80 determines that the ultrasonic wave application unit 320 has a defect, the computer 80 may issue a predetermined notification information by an alarm device (not shown).

[0066] As described above, the ultrasonic measurement jig 1 of the embodiment is formed by treating the plate-like member 10 to which the piezoelectric element 30 is attached as a pseudo wafer, and attaching the plate-like member 10 to the columnar member 20 which is likened to the workpiece (ingot 110). Therefore, in the ultrasonic vibration measurement method of the embodiment, vibration data when ultrasonic waves are applied by the ultrasonic application unit 320 under the same conditions as those for applying ultrasonic waves to form the peeling layer 123 on the workpiece can be obtained, and the vibration received by the plate-like member 10, which is the pseudo wafer, can be measured based on the vibration data. Therefore, an abnormality in the ultrasonic application unit 320 can be detected accurately and easily.

[0067] In addition, vibration data under the same conditions as when the wafer 130 is normally peeled off from the workpiece (ingot 110) is obtained in advance as reference data, and then the vibration data obtained during inspection after repeatedly operating the ultrasonic application unit 320 is compared with the reference data, thereby making it possible to quantitatively determine whether the ultrasonic application unit 320 is operating normally.

[0068] Furthermore, the ultrasonic measuring tool 1 of the embodiment outputs vibration data to the computer 80 via wireless communication, eliminating the need for complicated wiring and allowing the tool to be transported within the processing equipment. In addition, since there is no need to worry about interference with surrounding structures, even non-experts can perform the work safely.

[0069] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

[0070] [First Modification] <Ultrasonic measuring tool 2> The configuration of an ultrasonic measurement tool 2 according to a first modified example of the present invention will be described with reference to the drawings. Fig. 14 is a cross-sectional view that shows a schematic view of the ultrasonic measurement tool 2 according to the first modified example. In the ultrasonic measurement tool 2 of the first modified example shown in Fig. 14, the same components as those in the ultrasonic measurement tool 1 of the embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0071] The ultrasonic measurement jig 2 of the first modified example is different from the ultrasonic measurement jig 1 of the embodiment in the configurations of the columnar member 20-1 and the output section 40-1. Furthermore, the ultrasonic measurement jig 2 does not incorporate the averaging circuit section 50 and the battery 70, and the piezoelectric element 30 is directly connected to the oscilloscope 90 by a wired connection.

[0072] The columnar member 20-1 of the first modification includes a column portion 25 and a spacer portion 26. The spacer portion 26 is a cylindrical spacer having an outer diameter equal to that of the column portion 25. In other words, the columnar member 20 of the embodiment is integrally formed in a columnar shape including a recess 22 in the center, but the columnar member 20-1 of the first modification includes the column portion 25 and the ring-shaped spacer portion 26 surrounding the outer periphery of the recess 22, which are formed separately and fixed to each other. A piezoelectric element 30 attached to one surface 11 of the plate-like member 10 is accommodated in the space surrounded by the plate-like member 10, the column portion 25, and the spacer portion 26.

[0073] The output section 40-1 of the first modified example is a two-wire cord that connects an oscilloscope 90 outside the ultrasonic measurement tool 2 and the piezoelectric element 30 by wire. The two wires connect each of the two electrodes that configure the piezoelectric element 30 to the oscilloscope 90. The averaging of the vibration data is performed in the oscilloscope 90.

[0074] [Second Modification] <Ultrasonic measuring tool 3> The configuration of an ultrasonic measurement tool 3 according to a second modified example of the present invention will be described with reference to the drawings. Fig. 15 is a cross-sectional view that shows a schematic diagram of the ultrasonic measurement tool 3 according to the second modified example. Fig. 16 is a diagram showing an electric circuit configuration of the ultrasonic measurement tool 3 according to the second modified example. In the ultrasonic measurement tool 3 according to the second modified example shown in Figs. 15 and 16, the same components as those in the ultrasonic measurement tool 1 according to the embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0075] Compared to the ultrasonic measurement jig 1 of the embodiment, the ultrasonic measurement jig 3 of the second modified example has two types of piezoelectric elements, namely a measurement piezoelectric element 31 and a power generation piezoelectric element 32, instead of one type of piezoelectric element 30, a cable 71, and a power generation and charging circuit section 72.

[0076] The measurement piezoelectric element 31 has the same configuration and function as the piezoelectric element 30 of the embodiment. The power generation piezoelectric element 32 is a passive element that converts an applied pressure into a voltage, similar to the piezoelectric element 30 of the embodiment, and is configured to include a piezoelectric body and two electrodes sandwiching the piezoelectric body. The power generation piezoelectric element 32 is attached to the outer periphery of the measurement piezoelectric element 31 on one surface 11 of the plate-shaped member 10. The power generation piezoelectric element 32 is accommodated in the recess 22 of the columnar member 20 in a state in which one surface 11 of the plate-shaped member 10 and one surface 21 of the columnar member 20 are attached to each other. The power generation piezoelectric elements 32 of the second modified example have, for example, an outer diameter of 10 mm and a thickness of 250 μm, and 12 of them are evenly provided on the outer periphery of the measurement piezoelectric element 31. The power generation piezoelectric elements 32 may be annular with an outer diameter of 50 mm and an inner diameter of 40 mm, and may be provided concentrically with the measurement piezoelectric element 31.

[0077] The power-generating piezoelectric element 32 is electrically connected to the battery 70 via a cable 71. The cable 71 includes two wires that connect to each of the two electrodes. The power-generating piezoelectric element 32 converts the detected vibration data into a voltage value and outputs it to the power-generating and charging circuit unit 72. The power-generating and charging circuit unit 72 generates power from the vibration generated in the power-generating piezoelectric element 32 and stores the DC power. The power-generating and charging circuit unit 72 may, for example, rectify the AC voltage generated by the vibration using four bridge-connected diodes and convert it into DC power. The power-generating and charging circuit unit 72 may, for example, have a capacitor and store the DC power in the capacitor. The power-generating and charging circuit unit 72 supplies power to the battery 70 that supplies power to the output unit 40 and the absolute value circuit 51. The power-generating and charging circuit unit 72 may directly supply power to the output unit 40 and the absolute value circuit 51.

[0078] In this way, in the ultrasonic measurement tool 3 of the second modification, a power-generating piezoelectric element 32 is provided in addition to the measurement piezoelectric element 31, so that vibrations are measured and power is generated by the vibrations at the same time. This ensures that power is generated, and therefore the frequency of replacing or charging the battery 70 can be reduced.

[0079] [Third Modification] <Ultrasonic measuring tool 4> The configuration of an ultrasonic measurement jig 4 according to a third modified example of the present invention will be described with reference to the drawings. FIG. 17 is a cross-sectional view that shows a schematic diagram of the ultrasonic measurement jig 4 according to the third modified example. FIG. 18 is a diagram showing an electric circuit configuration of the ultrasonic measurement jig 4 according to the third modified example. FIG. 19 is a graph showing an example of vibration data detected by the piezoelectric element 33 according to the third modified example. In the ultrasonic measurement jig 4 according to the third modified example shown in FIGS. 17 and 18, the same components as those in the ultrasonic measurement jig 1 of the embodiment or the ultrasonic measurement jig 3 of the second modified example are denoted by the same reference numerals, and description thereof will be omitted.

[0080] Compared to the ultrasonic measurement tool 1 of the embodiment, the ultrasonic measurement tool 4 of the third modified example has a piezoelectric element 33 instead of the piezoelectric element 30, a cable 73, and a power generating and charging circuit section 72.

[0081] The piezoelectric element 33 has the same configuration as the piezoelectric element 30 of the embodiment, and also has the functions of the measurement piezoelectric element 31 and the power generation piezoelectric element 32 of the second modified example. The piezoelectric element 33 is electrically connected to the battery 70 via a cable 73. The cable 73 includes two wires that connect to each of the two electrodes. The piezoelectric element 33 converts the detected vibration data into a voltage value and outputs it to the averaging circuit section 50 and the power generation / charging circuit section 72.

[0082] The power generation / charging circuit section 72 may be configured to include a switch. In this case, as shown in Fig. 19, a predetermined time may be allocated to measurement by outputting vibration data to the averaging circuit section 50, and the other predetermined time may be allocated to power generation and charging by outputting vibration data to the power generation / charging circuit section 72. Alternatively, the data may be output simultaneously, so that measurement, power generation, and charging can be performed simultaneously.

[0083] In this way, in the ultrasonic measurement jig 4 of the third modified example, the piezoelectric element 33 is used for both ultrasonic measurement and power generation and charging. This makes it possible to measure vibration and secure power, thereby reducing the frequency of replacing or charging the battery 70. In addition, since it is used for both purposes, there is no need to provide a separate piezoelectric element 33.

[0084] [Other Modifications] For example, the integrally molded columnar member 20 of the embodiment, the second modification, and the third modification may be formed with a hole for passing a wired wiring therethrough, and may be connected to an oscilloscope 90 by wire. Alternatively, the thickness of the spacer 26 of the columnar member 20-1 of the first modification may be increased to incorporate the output unit 40, the averaging circuit unit 50, and the battery 70, and the columnar member 20-1 may be wirelessly connected to a computer 80. When transmitting vibration data to the outside by the output unit 40, power consumption may be reduced by transmitting intermittently at a predetermined time interval, for example, every second, instead of continuously. [Explanation of symbols]

[0085] 1, 2, 3, 4 Ultrasonic measurement fixture 10 Plate-shaped member 11 One Side 12 The other side 20, 20-1 Column member 21 One Side 22 Recess 23 Bottom 24 The Other Side 30, 33 Piezoelectric element 31 Piezoelectric element for measurement (piezoelectric element) 32 Power generating piezoelectric element (second piezoelectric element) 40, 40-1 Output section 50 Averaging circuit section 60 A / D conversion section 70 batteries 72 Power generation and charging circuit section 80 Computer 110 Ingot (workpiece) 121 Reforming section 122 Crack 123 Peeling layer 130 wafers 222 Laser Beam 320 Ultrasonic application unit

Claims

1. An ultrasonic measurement tool for measuring ultrasonic vibrations, A plate-like member; a columnar member having one surface on which a recess is formed and bonded to one surface of the plate-like member; a piezoelectric element attached to the one surface of the plate-like member and accommodated in the recess; an output section that outputs vibration data detected by the piezoelectric element to an outside; Equipped An ultrasonic measurement tool comprising:

2. a second piezoelectric element attached to the one surface of the plate-like member and accommodated in the recess; a battery connected to the second piezoelectric element by wire and supplying power to the output section; a power generating and charging circuit section that converts the vibration of the second piezoelectric element into electricity and supplies the electricity to the battery; Further comprising 2. The ultrasonic measuring tool according to claim 1 .

3. a battery connected to the piezoelectric element by wire and supplying power to the output section; a power generating and charging circuit section that converts the vibration of the piezoelectric element into electricity and supplies the electricity to the battery; Further comprising 2. The ultrasonic measuring tool according to claim 1 .

4. A method for measuring ultrasonic vibrations, comprising: a tool preparation step of preparing an ultrasonic measurement tool according to any one of claims 1 to 3; an ultrasonic applying step of applying ultrasonic waves to the ultrasonic measurement tool by placing an ultrasonic applying unit against the other surface of the plate-like member and operating the ultrasonic applying unit while supplying liquid between the ultrasonic applying unit and the other surface of the plate-like member; a measuring step of measuring vibrations received by the plate-like member based on vibration data detected by the piezoelectric element during the ultrasonic wave application step; Includes 1. A method for measuring ultrasonic vibrations.

5. A workpiece preparation step of preparing a workpiece in which a peeling layer including a modified portion and a crack extending from the modified portion is formed by irradiation with a laser beam; a confirmation step of confirming whether or not the workpiece can be normally separated from the peeling layer by applying ultrasonic waves to the workpiece using the ultrasonic application unit; a reference data acquisition step of measuring vibrations received by the plate-like member based on vibration data detected by the piezoelectric element while applying ultrasonic waves to the ultrasonic measurement jig using the ultrasonic application unit after confirming that the workpiece can be normally separated in the confirmation step; is carried out in advance before the ultrasonic application step and the measurement step, a determination step of determining whether or not the ultrasonic application unit is operating normally by comparing the result acquired by the reference data acquisition step with the result acquired by the measurement step; Further includes 5. The method for measuring ultrasonic vibration according to claim 4.

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