Inspection method and inspection apparatus

Abstract

This invention provides a non-destructive and simple inspection method that can determine whether a suitable starting point for division has been formed on the object under inspection, thereby ensuring the processing quality when dividing the object under inspection. [Solution] The method comprises: a division starting point formation step of moving a processing point along a division starting point that is set on the object to be inspected so as to form a division starting point along the division starting point line; a sound wave transmission and reception step performed after or during the division starting point formation step of transmitting a transmission wave that will be a sound wave propagating inside and / or on the surface of the object to be inspected, and receiving the sound wave as a reception wave; and an inspection step of identifying the position of the division starting point and / or determining whether the division starting point is exposed on the surface based on the characteristics of the reception wave.

Description

Technical Field

[0001] The present invention relates to an inspection method and an inspection apparatus.

Background Art

[0002] Semiconductor packages such as ICs (Integrated Circuits), which are essential components in various electronic devices such as mobile phones and personal computers, are manufactured through semiconductor manufacturing processes. This semiconductor manufacturing process is roughly divided into a pre-process of forming a plurality of devices each including a large number of circuit elements on one side of a wafer, and a post-process of packaging each of the plurality of chips manufactured from this wafer.

[0003] In the post-process, for example, a plurality of chips are manufactured by forming a starting point for division along the boundaries of a plurality of devices on the wafer and then applying an external force to divide the wafer (see, for example, Patent Document 1). This starting point for division includes, for example, a modified layer formed by irradiating the wafer with a laser beam having a wavelength that penetrates the material of the wafer (specifically, a layer including a modified portion where the crystal structure of the material of the wafer is disrupted and a crack extending through the modified portion), or a groove formed by cutting the wafer with a rotating annular cutting blade.

[0004] Note that even when observing the appearance of a wafer irradiated with a laser beam so that a modified layer is formed along the boundaries of a plurality of devices inside it, it may not be possible to confirm whether a modified layer is formed inside. Taking this point into account, prior to applying an external force to divide the wafer, it has been proposed to inspect whether a modified layer is formed inside the wafer along the boundaries of a plurality of devices by using sound waves (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] As described above, the processing quality when splitting a wafer is evaluated based, for example, on observations of the side surface of the manufactured chip (i.e., the surface newly exposed by the wafer splitting). If the evaluated processing quality does not reach the desired quality, the processing conditions for forming the splitting starting point on the wafer may be adjusted, and then the processing quality of the wafer split according to the new processing conditions may be evaluated again. In addition, such evaluations of processing quality may be performed not only prior to the start-up of the mass production line, but also while the mass production line is in operation.

[0007] When evaluating processing quality in this way, the processing quality needs to be evaluated every time the processing conditions are adjusted, which places a heavy burden on personnel. Therefore, as mentioned above, when manufacturing multiple chips, there is a need for a non-destructive and simple inspection of the splitting points formed on the wafer. Furthermore, from the perspective of improving the processing quality when splitting wafers, it is necessary not only to confirm whether or not splitting points are formed, but also to inspect whether or not they are suitable for ensuring the desired processing quality.

[0008] In view of these points, the object of the present invention is to provide an inspection method and inspection apparatus that can non-destructively and easily inspect whether a suitable starting point for division is formed on an object to be inspected, such as a wafer, in order to ensure processing quality when the object is divided. [Means for solving the problem]

[0009] According to one aspect of the present invention, an inspection method is provided comprising: a division starting point formation step of moving a processing point along a division starting point that is set on an object to be inspected so as to form a division starting point along the division starting point line set on the object to be inspected; a sound wave transmission and reception step performed after or during the division starting point formation step of transmitting a transmission wave that will be a sound wave propagating inside and / or on the surface of the object to be inspected, and receiving the sound wave as a reception wave; and an inspection step of identifying the position of the division starting point and / or determining whether the division starting point is exposed on the surface based on the characteristics of the reception wave.

[0010] In this inspection method, if the sound wave receiving unit is provided to receive the sound wave reflected due to the presence of the division point, it may be determined that the division point is exposed on the surface if the intensity of the received wave is greater than a first threshold during the inspection step. If the sound wave receiving unit is provided to receive the sound wave that has passed through the division point, it may be determined that the division point is exposed on the surface if the intensity of the received wave is less than a second threshold during the inspection step. Furthermore, in the inspection step, it may be confirmed that the division point is formed by comparing the frequency of the sound contained in the transmitted wave with the frequency of the sound contained in the received wave, and the location of the division point may be identified and / or it may be determined whether or not the division point is exposed on the surface. Furthermore, if the transmitted wave includes a Rayleigh wave, the inspection step may determine whether or not the splitting point is present on the surface by comparing the actual time required for the sound wave to actually propagate from the sound wave transmitting unit to the sound wave receiving unit in the sound wave transmission and reception process with the hypothetical time that is assumed to be required for the sound wave to propagate from the sound wave transmitting unit to the sound wave receiving unit when the splitting point is not formed. Alternatively, if the transmitted wave includes waves other than Rayleigh waves, the sound wave receiving unit is provided to receive the sound wave reflected due to the presence of the splitting point, the time required for the sound wave to propagate from the sound wave transmitting unit to the sound wave receiving unit is known in advance, and in the inspection step, if a peak is observed in a graph showing the time-dependent change in the intensity of the received wave at the point when the required time has elapsed since the transmitted wave, or if the intensity of the peak is greater than a threshold, it may be determined that the splitting point is present on the surface. Furthermore, in the inspection process, the position of the division starting point may be identified and / or it may be determined whether or not the division starting point is exposed on the surface by comparing the hypothetical characteristics assumed to be the characteristics of the received wave in the state in which the division starting point is formed with the characteristics of the received wave actually received by the sound wave receiving unit in the sound wave transmission and reception process.Furthermore, the transmitted wave may include two or more Rayleigh waves with different frequencies, and in the inspection process, the depth of the division point exposed on the surface, or the distance between the division point not exposed on the surface and the surface, may be identified as the position of the division point by comparing the attenuation rates of the two or more Rayleigh waves on the object under inspection. The transmitted wave may also include a Lamb wave.

[0011] According to another aspect of the present invention, a first division starting point formation step is performed in which a processing point is moved along a first division starting point along a first division starting point set on an object to be inspected; a first sound wave transmission and reception step is performed after or during the first division starting point formation step in which a sound wave transmission unit transmits a first transmission wave which becomes a first sound wave propagating inside and / or on the surface of the object to be inspected, and a sound wave reception unit receives the first sound wave as a first reception wave; and a second division starting point is formed along a second division starting point set on the object to be inspected so as to be parallel to the first division starting point, performed after the first sound wave transmission and reception step. An inspection method is provided, comprising: a second division starting point formation step of moving the processing point along the second division planned line; a second sound wave transmission and reception step performed after or during the second division starting point formation step, in which the sound wave transmission unit transmits a second transmission wave which becomes a second sound wave propagating through the inside and / or surface of the object under inspection, and the sound wave receiving unit receives the second sound wave as a second reception wave; and an inspection step of identifying the respective positions of the first division starting point and the second division starting point based on the first reception wave and the second reception wave, and / or determining whether the respective first division starting point and the second division starting point are exposed on the surface.

[0012] Furthermore, this inspection method further comprises: a third division starting point formation step performed after the second sound wave transmission / reception step, in which the processing point is moved along the third division starting point to form a third division starting point along a third division planned line set on the object to be inspected so as to be parallel to the first division planned line and the second division planned line; and a third sound wave transmission / reception step performed after or during the third division starting point formation step, in which the sound wave transmission unit transmits a third transmission wave which becomes a third sound wave propagating through the inside and / or surface of the object to be inspected, and the sound wave receiving unit receives the third sound wave as a third reception wave, wherein in the inspection step, it may be determined whether or not the second division starting point is exposed on the surface by comparing the difference in characteristics between the first reception wave and the second reception wave, and the difference in characteristics between the second reception wave and the third reception wave.

[0013] Furthermore, in these inspection methods, the sound wave transmitting unit may have a plurality of sound wave transmitters, and the sound wave receiving unit may have a plurality of sound wave receivers, each receiving only the sound waves transmitted from any one of the plurality of sound wave transmitters among the sound waves propagated inside and / or on the surface of the object under inspection, or a plurality of sound wave receivers, each receiving the sound waves transmitted from each of the plurality of sound wave transmitters among the sound waves propagated inside and / or on the surface of the object under inspection.

[0014] Alternatively, in these inspection methods, the sound wave transmitting unit may have a plurality of sound wave transmitters capable of transmitting a plurality of sound waves that are focused at a desired position inside the object under inspection or that form a wavefront perpendicular to a desired direction. In this case, the plurality of sound wave transmitters may change the desired position over time to follow the processing point moving inside the object under inspection, or transmit the plurality of sound waves so that the processing point moving inside the object under inspection is positioned in the desired direction with respect to the wavefront.

[0015] According to yet another aspect of the present invention, an inspection apparatus is provided comprising: a holding unit for holding an object to be inspected on a holding surface on which a division starting point is formed; a sound wave transmitting unit for transmitting a transmitting wave which is a sound wave propagating through the inside and / or surface of the object to be inspected held on the holding surface; a sound wave receiving unit for receiving the sound wave that has propagated through the inside and / or surface of the object to be inspected as a received wave; and a controller that can communicate with the holding unit, the sound wave transmitting unit and the sound wave transmitting unit, wherein the controller has a memory for storing data indicating the received wave and a processor for identifying the position of the division starting point and / or determining whether the division starting point is exposed on the surface based on the characteristics of the received wave.

[0016] In this inspection device, the sound wave transmitting unit and the sound wave receiving unit do not need to move relative to the holding unit. Alternatively, the sound wave transmitting unit and the sound wave receiving unit may be provided in contact with the holding unit.

[0017] Furthermore, the sound wave transmitting unit and the sound wave receiving unit may be arranged along the outer periphery of a rectangular area included in the holding surface in a plan view. Alternatively, the sound wave transmitting unit and the sound wave receiving unit may be arranged along the outer periphery of a circular area included in the holding surface in a plan view.

[0018] Furthermore, the inspection apparatus may further include a movable member on which the sound wave transmitting unit and the sound wave receiving unit are provided, and a moving mechanism for moving the movable member between an inspection position in which the sound wave transmitting unit and the sound wave receiving unit are positioned such that the transmitted wave and the received wave are, respectively, sound waves that propagate or have propagated through the inside and / or surface of the object to be inspected held on the holding surface, and a standby position in which the sound wave transmitting unit and the sound wave receiving unit are positioned such that the transmitted wave and the received wave are sound waves that do not propagate or have not propagated through the inside and / or surface of the object to be inspected held on the holding surface.

[0019] Furthermore, in this inspection apparatus, the sound wave transmitting unit may have a plurality of sound wave transmitters, and the sound wave receiving unit may have a plurality of sound wave receivers, each receiving only the sound waves transmitted from any one of the plurality of sound wave transmitters among the sound waves propagated inside and / or on the surface of the object under inspection, or a plurality of sound wave receivers, each receiving the sound waves transmitted from each of the plurality of sound wave transmitters among the sound waves propagated inside and / or on the surface of the object under inspection.

[0020] Alternatively, in this inspection apparatus, the sound wave transmitting unit may have a plurality of sound wave transmitters capable of transmitting a plurality of sound waves that are focused at a desired position inside the object under inspection or that form a wavefront perpendicular to a desired direction.

[0021] Furthermore, the inspection device may further include a laser irradiation unit capable of irradiating a laser beam into the interior of the object to be inspected, which is held in the holding surface, to form a modified layer and a crack extending through the modified layer as the starting point for splitting. Alternatively, the inspection device may further include a cutting unit having a cutting blade for forming a groove in the object to be inspected, which is held in the holding surface, as the starting point for splitting. [Effects of the Invention]

[0022] In this invention, the position of the splitting starting point is identified and / or whether the splitting starting point is exposed on the surface, based on the characteristics of sound waves (received waves) propagating through the inside and / or surface of the object under inspection. If the position of the splitting starting point is deviated from the desired position and / or the splitting starting point is not exposed on the surface, there is a risk that the object under inspection cannot be split with the desired processing quality.

[0023] In other words, identifying the location of the splitting point and / or whether the splitting point is exposed on the surface greatly affects the processing quality when splitting the object under inspection. Therefore, according to the present invention, it becomes possible to non-destructively and simply inspect whether a splitting point suitable for ensuring processing quality when splitting the object under inspection has been formed on the object under inspection.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a wafer. [Figure 2] FIG. 2 is a perspective view schematically showing an example of a processing and inspection apparatus capable of processing a wafer as a workpiece and inspecting it as an inspection object. [Figure 3] FIG. 3 is a plan view schematically showing an example of a holding part, a sound wave transmitting part, and a sound wave receiving part. [Figure 4] FIG. 4 is a block diagram schematically showing an example of the hardware constituting a controller. [Figure 5] FIG. 5 is a flowchart schematically showing an example of a processing and inspection method. [Figure 6] FIG. 6(A) is a perspective view schematically showing the state of a modification layer formation step, and FIGS. 6(B) and 6(C) are partial enlarged cross-sectional views schematically showing examples of the modification layer formed on the wafer in the modification layer formation step. [Figure 7] FIG. 7(A) is a partial enlarged cross-sectional view schematically showing the sound wave propagating inside a wafer having a modification layer including a crack exposed on one surface, FIG. 7(B) is a partial enlarged cross-sectional view schematically showing the sound wave propagating on the surface of a wafer having a modification layer including a crack exposed on one surface, FIG. 7(C) is a partial enlarged cross-sectional view schematically showing the sound wave propagating inside a wafer having a modification layer including a crack not exposed on one surface, and FIG. 7(D) is a partial enlarged cross-sectional view schematically showing the sound wave propagating on the surface of a wafer having a modification layer including a crack not exposed on one surface. [Figure 8] FIG. 8 is a plan view schematically showing another example of a holding part, a sound wave transmitting part, and a sound wave receiving part. [Figure 9] FIG. 9 is a perspective view schematically showing an example of a sound wave transmitting part and a sound wave receiving part provided so as to be movable relative to a holding part. [Figure 10]Figures 10(A), 10(B), and 10(C) respectively schematically show how multiple transmitted waves from multiple sound wave transmitters included in the sound wave transmission unit are combined. [Figure 11] Figure 11 is a flowchart schematically illustrating another example of a processing inspection method. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described with reference to the attached drawings. Figure 1 is a schematic perspective view showing an example of a wafer. The wafer 11 shown in Figure 1 has a surface divided into one surface 11a, another surface 11b which is generally parallel to the first surface 11a, and an outer peripheral surface 11c which is located between the outer periphery of the first surface 11a and the outer periphery of the other surface 11b, and is made of, for example, silicon (Si).

[0026] Furthermore, multiple devices 13 are provided on one side 11a of the wafer 11. Each device 13 includes, for example, a semiconductor element for constituting an IC, a semiconductor memory, or a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

[0027] Furthermore, the multiple devices 13 are arranged in a matrix. That is, the boundaries of the multiple devices 13 extend in a grid pattern. On the wafer 11, the linearly extending portions of the boundaries of the multiple devices 13 are set as division lines 15, and multiple chips are manufactured by dividing the wafer 11 along all of these boundaries.

[0028] There are no restrictions on the material, shape, structure, or size of wafer 11. Wafer 11 may be made of a semiconductor other than silicon (for example, silicon carbide (SiC) or gallium nitride (GaN)). Similarly, there are no restrictions on the type, quantity, shape, structure, size, or arrangement of the multiple devices 13.

[0029] Furthermore, the wafer 11 may be integrated with the ring frame via a support member fixed to one side 11a or the other side 11b. This support member is, for example, a tape containing an adhesive layer that adheres to the other side 11b of the wafer 11. Alternatively, the support member may be a sheet that does not contain an adhesive layer that is heat-pressed to the other side 11b of the wafer 11.

[0030] Figure 2 is a schematic perspective view showing an example of a processing and inspection apparatus (inspection apparatus) capable of processing a wafer 11 as a workpiece and inspecting it as an object to be inspected. Note that the directions indicated by arrows X (X direction) and Y (Y direction) in Figure 2 are mutually orthogonal directions on the horizontal plane. Also, the direction indicated by arrow Z (Z direction) is a direction perpendicular to the X direction and Y direction, respectively (vertical direction).

[0031] In short, the processing inspection apparatus 2 shown in Figure 2 can form a modified layer on a wafer 11 along the boundaries of multiple devices 13, and can also inspect whether the modified layer is suitable for ensuring processing quality when dividing the wafer 11 along these boundaries. This processing inspection apparatus 2 has a base 4 that supports each component.

[0032] A horizontal movement mechanism 6 is positioned on the upper surface of the base 4. The horizontal movement mechanism 6 has a pair of guide rails 8 that are fixed to the upper surface of the base 4 and extend along the Y direction. A Y-direction movement plate 10 is connected to the upper side of the pair of guide rails 8 in a manner that allows it to slide along the pair of guide rails 8. A screw shaft 12 extending along the Y direction is positioned between the pair of guide rails 8.

[0033] A motor 14 for rotating the screw shaft 12 is connected to one end of the screw shaft 12. A nut (not shown) is provided on the surface of the screw shaft 12, where a helical groove is formed, to house a number of balls that roll on the surface of the rotating screw shaft 12, thus forming a ball screw. That is, when the screw shaft 12 rotates, the number of balls circulate within the nut, causing the nut to move along the Y direction.

[0034] Furthermore, this nut is fixed to the underside of the Y-direction moving plate 10. Therefore, when the screw shaft 12 is rotated by the motor 14, the Y-direction moving plate 10 moves along the Y-direction together with the nut.

[0035] A pair of guide rails 16 extending along the X direction are fixed to the upper surface of the Y-direction moving plate 10. An X-direction moving plate 18 is connected to the upper surface of the pair of guide rails 16 in a manner that allows it to slide along the pair of guide rails 16. A screw shaft 20 extending along the X direction is positioned between the pair of guide rails 16.

[0036] A motor 22 for rotating the screw shaft 20 is connected to one end of the screw shaft 20. A nut (not shown) is provided on the surface of the screw shaft 20, which has a helical groove, to house a number of balls that roll on the surface of the rotating screw shaft 20, thus forming a ball screw. That is, when the screw shaft 20 rotates, the number of balls circulate within the nut, causing the nut to move along the X direction.

[0037] Furthermore, this nut is fixed to the underside of the X-direction moving plate 18. Therefore, when the screw shaft 20 is rotated by the motor 22, the X-direction moving plate 18 moves along the X-direction together with the nut.

[0038] On the upper surface of the X-direction moving plate 18, a holding section 24 and four sound wave transmitting / receiving sections 26a, 26b, 26c, and 26d are provided. Figure 3 is a schematic plan view showing the holding section 24 and the sound wave transmitting / receiving sections 26a, 26b, 26c, and 26d. The holding section 24 has a disc-shaped frame 24a made of ceramics or the like. The frame 24a has a disc-shaped bottom wall and cylindrical side walls that rise from the outer peripheral end of this bottom wall.

[0039] Furthermore, a disc-shaped porous plate 24b, for example, made of porous ceramics, is fixed to the recess defined by the bottom wall and side wall of the frame 24a. This porous plate 24b has a diameter approximately equal to the inner diameter of the side wall of the frame 24a. The porous plate 24b is also positioned so that its upper surface is flush with the upper surface of the side wall of the frame 24a.

[0040] Furthermore, the porous plate 24b communicates with a suction source (not shown), such as an ejector, via a channel formed in the bottom wall of the frame 24a. The upper surface of the side wall of the frame 24a and the upper surface of the porous plate 24b are parallel to the X and Y directions, respectively, and function as holding surfaces of the holding part 24.

[0041] Specifically, when a single wafer 11 or a wafer 11 integrated with a ring frame via a support member is brought into the processing and inspection apparatus 2, the wafer 11 or support member covers the porous plate 24b, and the wafer 11 is placed in the holding section 24 such that the center of the wafer 11 and the center of the holding surface overlap in the Z direction.

[0042] Then, when the suction source communicating with the porous plate 24b is activated in this state, an attractive force acts on the wafer 11 directly or indirectly. As a result, the wafer 11 is held on the holding surface of the holding part 24.

[0043] Furthermore, four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d are built into the side wall of the frame 24a, such that their respective rectangular upper surfaces are flush with the upper surface of the side wall of the frame 24a and the upper surface of the porous plate 24b. In other words, the four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d are provided in contact with the holding unit 24 so as not to move relative to the holding unit 24.

[0044] Specifically, the four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d are arranged in a plan view at approximately equal angular intervals with respect to the center of the holding surface of the holding unit 24. That is, in a plan view, the four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d are arranged such that sound wave transmitting and receiving unit 26a and sound wave transmitting and receiving unit 26c face each other via the porous plate 24b, and sound wave transmitting and receiving unit 26b and sound wave transmitting and receiving unit 26d face each other.

[0045] Furthermore, the four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d are arranged along the outer periphery of a rectangular region included in the holding surface of the holding unit 24. Specifically, the pair of sound wave transmitting and receiving units 26a and 26c are provided along a pair of edges extending along a first direction D1 on the outer periphery of this region. The pair of sound wave transmitting and receiving units 26b and 26d are provided along a pair of edges extending along a second direction D2 perpendicular to the first direction D1 on the outer periphery of this region.

[0046] Furthermore, the pair of sound wave transmitting and receiving units 26a and 26b are spaced apart in a direction shifted 45° counterclockwise from the first direction D1 in a plan view. Similarly, the pair of sound wave transmitting and receiving units 26c and 26d are spaced apart in a direction shifted 45° counterclockwise from the first direction D1 in a plan view. Furthermore, the pair of sound wave transmitting and receiving units 26a and 26d are spaced apart in a direction shifted 45° clockwise from the first direction D1 in a plan view. Similarly, the pair of sound wave transmitting and receiving units 26b and 26c are spaced apart in a direction shifted 45° clockwise from the first direction D1 in a plan view.

[0047] Each sound wave transmitting / receiving unit 26a, 26b, 26c, 26d has, for example, at least one sound wave transmitter such as a contact-type transmitting probe. This sound wave transmitter is capable of transmitting a wave that propagates inside and / or on the surface of the wafer 11 held on the holding surface so as to face the sound wave transmitting / receiving units 26a, 26b, 26c, 26d which are arranged opposite each other in a plan view. That is, the transmitted waves from each sound wave transmitting / receiving unit 26a, 26c extending along the first direction D1 propagate, for example, in the second direction D2 or the opposite direction, and the transmitted waves from each sound wave transmitting / receiving unit 26b, 26d extending along the second direction D2 propagate, for example, in the first direction D1 or the opposite direction.

[0048] In this specification, the sound waves propagating on the surface of the wafer 11 mean sound waves that penetrate from the surface to a depth (penetration depth) of 0.5 to 1.0 times their wavelength (i.e., the value obtained by dividing their speed by their frequency), but do not penetrate any further.

[0049] The sound waves propagating inside and / or on the surface of the wafer 11 are ultrasonic waves, such as bulk waves or guided waves, that propagate at a speed that varies depending on the material of the wafer 11. These bulk waves include longitudinal and transverse waves. Guided waves include Rayleigh waves, Lamb waves, Love waves, and Stoneley waves. It is preferable that the sound waves are guided waves (especially Lamb waves) rather than bulk waves in order to suppress attenuation in the wafer 11 and enable long-distance propagation.

[0050] Furthermore, each sound wave transmitting / receiving unit 26a, 26b, 26c, 26d may have, in addition to or instead of a sound wave transmitter, at least one sound wave receiver such as a contact-type receiving probe. This sound wave receiver can, for example, receive sound waves transmitted from at least one of the four sound wave transmitting / receiving units 26a, 26b, 26c, 26d and propagated through the inside and / or surface of the wafer 11 held on the holding surface. Moreover, if a modified layer is formed on the wafer 11, the received wave will be a sound wave whose characteristics have been altered due to transmission through the modified layer (transmitted wave) or a sound wave whose characteristics have been altered due to reflection by the modified layer (reflected wave).

[0051] Specifically, when the modified layer extends along the first direction D1, transmitted waves originating from the sound wave transmitting / receiving unit 26c and / or reflected waves originating from the sound wave transmitting / receiving unit 26a are received as received waves in the sound wave transmitting / receiving unit 26a, and transmitted waves originating from the sound wave transmitting / receiving unit 26a and / or reflected waves originating from the sound wave transmitting / receiving unit 26c are received as received waves in the sound wave transmitting / receiving unit 26c.

[0052] Furthermore, if the modified layer extends along the second direction D2, transmitted waves originating from the sound wave transmitting / receiving unit 26d and / or reflected waves originating from the sound wave transmitting / receiving unit 26b are received as received waves in the sound wave transmitting / receiving unit 26b, and transmitted waves originating from the sound wave transmitting / receiving unit 26b and / or reflected waves originating from the sound wave transmitting / receiving unit 26d are received as received waves in the sound wave transmitting / receiving unit 26d.

[0053] Furthermore, in a plan view, if the modified layer extends along a direction shifted by, for example, 45° counterclockwise from the first direction D1, then a reflected wave originating from one of the pair of sound wave transmitting / receiving units 26a, 26b (specifically, a sound wave reflected on one side of the modified layer) is received as a received wave on the other side, and a reflected wave originating from one of the pair of sound wave transmitting / receiving units 26c, 26d (specifically, a sound wave reflected on the other side of the modified layer) is received as a received wave on the other side.

[0054] Furthermore, in a plan view, if the modified layer extends along a direction shifted by, for example, 45° clockwise from the first direction D1, a reflected wave originating from one of the pair of sound wave transmitting / receiving units 26a, 26d (specifically, a sound wave reflected on one side of the modified layer) is received as a received wave on the other unit, and a reflected wave originating from one of the pair of sound wave transmitting / receiving units 26b, 26c (specifically, a sound wave reflected on the other side of the modified layer) is received as a received wave on the other unit.

[0055] In addition, a rotation mechanism (not shown) including a motor is connected to the holding part 24. When this rotation mechanism is operated, the holding part 24 and the four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d rotate around a straight line passing through the center of the holding surface of the holding part 24 and parallel to the Z direction as the axis of rotation. Therefore, by operating this rotation mechanism, it is possible to change the angle between the first direction D1 or the second direction D2 and the X direction or the Y direction.

[0056] Furthermore, when the horizontal movement mechanism 6 described above is operated, the holding unit 24 and the four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d move along the X and / or Y directions. In addition, as shown in Figure 2, a support structure 30 having sides that are generally parallel to the Y and Z directions is provided behind the horizontal movement mechanism 6.

[0057] A vertical movement mechanism 32 is positioned on the side of the support structure 30. The vertical movement mechanism 32 has a pair of guide rails 34 that are fixed to the side of the support structure 30 and extend along the Z direction. A Z-direction movement plate 36 is connected to the surface side of the pair of guide rails 34 in a manner that allows it to slide along the pair of guide rails 34. A screw shaft (not shown) extending along the Z direction is positioned between the pair of guide rails 34.

[0058] A motor 38 for rotating the screw shaft is connected to the upper end (one end) of the screw shaft. A nut (not shown) is provided on the surface of the screw shaft, where a helical groove is formed, to house a number of balls that roll on the surface of the rotating screw shaft, thus forming a ball screw. In other words, when this screw shaft rotates, the number of balls circulate within the nut, causing the nut to move along the Z direction.

[0059] Furthermore, this nut is fixed to the back side of the Z-direction moving plate 36. Therefore, when the motor 38 rotates the screw shaft located between the pair of guide rails 34, the Z-direction moving plate 36 moves along the Z-direction together with the nut.

[0060] A support 40 is fixed to the surface side of the Z-direction moving plate 36. This support 40 supports some of the components of the laser irradiation unit 42. The laser irradiation unit 42 also has a laser oscillator (not shown) fixed to the base 4. The laser oscillator has, for example, Nd:YAG as the laser medium and emits a laser beam with a wavelength that penetrates the wafer 11 (for example, 1064 nm or 1342 nm). This laser beam is, for example, a pulsed laser beam with a frequency of 60 kHz.

[0061] The laser beam emitted from the laser oscillator is guided to the head 44 after its output is adjusted by an attenuator (not shown). The head 44 houses a focusing lens (not shown) and the like for focusing the laser beam. The laser beam focused by this focusing lens is then emitted towards the holding surface of the holding part 24. The head 44 is located at the front end of the cylindrical housing 46. A support 40 is fixed to the rear side of the housing 46.

[0062] Furthermore, an imaging unit 48 is fixed to the front side of the housing 46. This imaging unit 48 includes, for example, a light source such as an LED (Light Emitting Diode), an objective lens, and an image sensor such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

[0063] When the vertical movement mechanism 32 described above is operated, the head 44, housing 46, and imaging unit 48 move along the Z direction. Furthermore, a cover (not shown) is provided on the base 4 to cover the above-mentioned components. An interface unit 50 is located on the front of this cover.

[0064] The interface unit 50 is a touch panel composed of, for example, an input device such as a capacitive or resistive touch sensor and a display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display, and functions as a user interface.

[0065] The processing inspection apparatus 2 described above further includes a controller capable of communicating with its components (horizontal movement mechanism 6, holding unit 24, sound wave transmitting / receiving units 26a, 26b, 26c, 26d, vertical movement mechanism 32, laser irradiation unit 42, imaging unit 48, and interface unit 50, etc.). Figure 4 is a schematic block diagram showing an example of the hardware constituting this controller.

[0066] The controller 52 shown in Figure 4 includes a processor 52a and a memory 52b. The processor 52a is composed of, for example, a CPU (Central Processing Unit). The memory 52b is composed of, for example, volatile memory such as DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory) and non-volatile memory such as an SSD (Solid State Drive) (NAND flash memory) or an HDD (Hard Disk Drive) (magnetic storage device).

[0067] The processor 52a can read various programs stored in the memory 52b and control the components of the processing inspection device 2. In addition to various programs, the memory 52b can also store various data used when these programs are being executed by the processor 52a.

[0068] Examples of data stored in memory 52b include the intensity threshold of the received wave, or the threshold time required for the sound wave to propagate across the surface of wafer 11. This data may also include characteristics (virtual characteristics) that are assumed to be characteristics of the received wave when the desired modified layer is formed. These virtual characteristics can be obtained, for example, by pre-inspecting a wafer that has the desired modified layer formed on it and has a structure similar to wafer 11.

[0069] Furthermore, the program stored in memory 52b is a program for forming a modified layer on the wafer 11 held on the holding surface of the holding unit 24, and then inspecting the wafer 11 with the modified layer formed on it using sound waves. Figure 5 is a schematic flowchart showing an example of a processing inspection method (inspection method) that is carried out by controlling the components of the processing inspection apparatus 2 according to this program.

[0070] In this method, first, the focusing point (processing point) where the laser beam is focused is moved along the planned division line 15 to form a modified layer (division starting point) along the planned division line 15 (modified layer formation step S1). Figure 6(A) is a schematic perspective view showing the modified layer formation step S1. Figures 6(B) and 6(C) are schematic enlarged cross-sectional views showing examples of modified layers formed on the wafer 11 in the modified layer formation step S1.

[0071] In the modified layer formation process S1, first, the wafer 11 is placed on the holding surface of the holding unit 24, either directly or via a support member, so that one side 11a faces upward. At this time, the orientation of the wafer 11 is adjusted according to how at least one of the four sound wave transmitting / receiving units 26a, 26b, 26c, and 26d is to function. This adjustment is performed, for example, by referring to an image formed by the imaging unit 48 imaging the wafer 11 placed on the holding surface of the holding unit 24.

[0072] Specifically, when one of the pair of sound wave transmitting / receiving units 26a, 26c is configured to function as a sound wave transmitting unit and the other as a sound wave receiving unit, or when at least one of them is configured to function as both a sound wave transmitting and receiving unit, the orientation of the wafer 11 is adjusted so that the planned division line 15 aligns with the first direction D1. Furthermore, when one of the pair of sound wave transmitting / receiving units 26b, 26d is configured to function as a sound wave transmitting unit and the other as a sound wave receiving unit, or when at least one of them is configured to function as both a sound wave transmitting and receiving unit, the orientation of the wafer 11 is adjusted so that the planned division line 15 aligns with the second direction D2.

[0073] Furthermore, when one of a pair of sound wave transmitting / receiving units 26a, 26b or 26c, 26d, which are separated in a direction shifted 45° counterclockwise from the first direction D1 in a plan view, is configured to function as a sound wave transmitting unit and the other as a sound wave receiving unit, the orientation of the wafer 11 is adjusted so that the planned division line 15 aligns with a direction shifted 45° counterclockwise from the first direction D1 in a plan view.

[0074] Next, the suction source is operated so that the wafer 11 is held on the holding surface of the holding part 24. Then, the rotation mechanism rotates the holding part 24 etc. so that the division line 15 is parallel to the X direction. Next, the horizontal movement mechanism 6 moves the holding part 24 etc. along the X direction and / or Y direction so that a region of the wafer 11 near one end in the Y direction is positioned in the X direction when viewed from the head 44 in a plan view.

[0075] Next, the vertical movement mechanism 32 moves the head 44 and the like along the Z direction so that the focal point where the laser beam LB emitted from the head 44 is focused is positioned at a target depth on one surface 11a of the wafer 11. In the modified layer formation process S1, for example, the target depth is set to less than half the thickness of the wafer 11 so that this focal point is closer to one surface 11a than to the other surface 11b.

[0076] Next, while the laser beam LB is emitted from the head 44, the horizontal movement mechanism moves the head 44 along the X direction so that the wafer 11 passes the focal point in a plan view (see Figure 6(A)). That is, the laser beam LB is irradiated onto the wafer 11 with the X direction as the scanning direction of the laser beam LB. As a result, a modified layer 17 is formed on the wafer 11 (see Figures 6(B) and 6(C)).

[0077] Specifically, a modified region 17a, in which the crystal structure of the material is disordered, is formed inside the wafer 11, centered on the focal point where the laser beam LB is focused. Furthermore, when the modified region 17a is formed inside the wafer 11, the volume of the wafer 11 expands, generating internal stress in the wafer 11. This internal stress is then relieved, for example, by the extension of cracks 17b and 17c that penetrate the modified region 17a along the thickness direction of the wafer 11.

[0078] In the modified layer formation step S1, for example, the irradiation conditions of the laser beam LB are set so that a crack 17b appears on one surface 11a (see Figure 6(B)). However, if these irradiation conditions are inappropriate and / or if there are defects on the laser irradiation unit 42 side and / or the wafer 11 side, a crack 17c that does not appear on one surface 11a may be formed (see Figure 6(C)).

[0079] Furthermore, defects on the laser irradiation unit 42 side include, for example, a decrease in the output (power) of the laser beam LB and / or a widening of the focal point due to deterioration of its components. Defects on the wafer 11 side include, for example, the adhesion of foreign matter to one surface 11a and / or segregation of impurities inside it.

[0080] Furthermore, cracks 17c that do not appear on surface 11a are constrained to suppress widening of cracks 17c in the vicinity of surface 11a, whereas cracks 17b that appear on surface 11a are not constrained in this way. Therefore, the width of cracks 17b tends to be larger than the width of cracks 17c, especially in the vicinity of surface 11a.

[0081] After the modified layer formation process S1, the sound wave transmitting unit transmits a transmission wave that will propagate through the inside and / or surface of the wafer 11, and the sound wave receiving unit receives the said sound wave as a reception wave (sound wave transmission / reception process S2). In this sound wave transmission / reception process S2, a transmission wave is transmitted toward the wafer 11 from at least one of the four sound wave transmission / reception units 26a, 26b, 26c, and 26d. For convenience, the following describes an embodiment in which a transmission wave is transmitted from each of a pair of sound wave transmission / reception units 26a and 26b.

[0082] When sound waves (incident waves) propagating through the inside and / or surface of the wafer 11 are transmitted from each of the pair of sound wave transmitting / receiving units 26a and 26b, a signal indicating the transmitted wave (for example, a signal indicating the change in its intensity over time) is transmitted from each sound wave transmitting / receiving unit 26a and 26b to the controller 52. In addition to this signal, a signal indicating the time at which the transmitted wave was transmitted may also be transmitted from each sound wave transmitting / receiving unit 26a and 26b to the controller 52.

[0083] Here, if the orientation of the wafer 11 is adjusted so that the division line 15 aligns with the first direction D1, the reflected wave is received as the received wave in the sound wave transmitting / receiving unit 26a, and the transmitted wave is received as the received wave in the sound wave transmitting / receiving unit 26c. If the orientation of the wafer 11 is adjusted so that the division line 15 aligns with the second direction D2, the reflected wave is received as the received wave in the sound wave transmitting / receiving unit 26b, and the transmitted wave is received as the received wave in the sound wave transmitting / receiving unit 26d.

[0084] Furthermore, if the wafer 11 is oriented so that the division line 15 aligns with a direction shifted 45° counterclockwise from the first direction D1 in a plan view, the reflected wave is received as a received wave in each of the pair of sound wave transmitting / receiving units 26a and 26b.

[0085] Figures 7(A) and 7(B) are schematic enlarged cross-sectional views illustrating sound waves propagating inside or on the surface of a wafer 11 in which a modified layer 17 containing a crack 17b exposed on one surface 11a is formed. Figures 7(C) and 7(D) are schematic enlarged cross-sectional views illustrating sound waves propagating inside or on the surface of a wafer 11 in which a modified layer 17 containing a crack 17c not exposed on one surface 11a is formed.

[0086] In Figures 7(A) and 7(C), for convenience, sound waves propagating along directions parallel to one surface 11a and the other surface 11b of the wafer 11 are shown. However, these sound waves may also propagate along directions intersecting the one surface 11a and the other surface 11b of the wafer 11. That is, these sound waves may propagate through the interior of the wafer 11 while being reflected once or more by the one surface 11a and / or the other surface 11b.

[0087] Of the incident wave IW, at least a portion that is directed towards the modified layer 17 is reflected by the modified layer 17 and becomes a reflected wave RW, thus reducing the intensity of the transmitted wave TW. Furthermore, if the modified layer 17 contains a crack 17b, the intensity of the reflected wave RW becomes greater due to the difference in width between cracks 17b and 17c, compared to the case where a crack 17c is present, thus reducing the intensity of the transmitted wave TW. On the other hand, of the incident wave IW, the portion that is directed towards the area where the modified layer 17 is not formed is not reflected by the modified layer 17, and the intensity of the transmitted wave TW is maintained.

[0088] Therefore, when a modified layer 17 containing a crack 17b is formed on the wafer 11, the intensity of the reflected wave RW propagating inside it increases and the intensity of the transmitted wave TW decreases compared to when a modified layer 17 containing a crack 17c is formed (see Figures 7(A) and 7(C)), and the intensity of the reflected wave RW propagating on its surface (specifically, one surface 11a) increases and the intensity of the transmitted wave TW decreases (see Figures 7(B) and 7(D)).

[0089] Furthermore, in wafers 11 where a modified layer 17 containing crack 17b is formed, the sound wave propagating along one surface 11a of the transmitted wave TW (the former sound wave) follows the crack 17b, whereas in wafers 11 where a modified layer 17 containing crack 17c is formed, the sound wave propagating along one surface 11a of the transmitted wave TW (the latter sound wave) does not follow the crack 17c. Therefore, the time required for the former sound wave to propagate along one surface 11a of wafer 11 is longer than the time required for the latter sound wave to propagate along one surface 11a of wafer 11.

[0090] Then, when the reflected wave RW or transmitted wave TW is received as a received wave by at least one of the four sound wave transceivers 26a, 26b, 26c, and 26d, a signal indicating the received wave (for example, a signal indicating the change in its intensity over time) is transmitted from at least one of these units to the controller 52. In addition to this signal, a signal indicating the time when the received wave was received by at least one of the four sound wave transceivers 26a, 26b, 26c, and 26d may also be transmitted to the controller 52.

[0091] After the sound wave transmission / reception process S2, the location of the modified layer 17 is determined based on the characteristics of the received wave, and / or it is determined whether or not the modified layer 17 is exposed on the surface (inspection process S3). The location of the modified layer 17 is determined, for example, based on the time it takes for a sound wave to actually originate from at least one of the four sound wave transmission / reception units 26a, 26b, 26c, 26d, be reflected by the modified layer 17, and then propagate to the same or another sound wave transmission / reception unit 26a, 26b, 26c, or 26d.

[0092] Furthermore, whether or not the modified layer 17 (specifically, its crack 17b) is exposed on the surface is determined, for example, by comparing the intensity of the received wave with a threshold value stored in memory 52b.

[0093] Specifically, when the reflected wave RW becomes the received wave, the processor 52a determines that the modified layer 17 is exposed on the surface (specifically, one of its surfaces 11a) if the intensity of the received wave is greater than the intensity threshold (first threshold) for the reflected wave RW stored in memory 52b. On the other hand, when the transmitted wave TW becomes the received wave, the processor 52a determines that the modified layer 17 is exposed on the surface if the intensity of the received wave is less than the intensity threshold (second threshold) for the transmitted wave TW stored in memory 52b.

[0094] Alternatively, if the received wave includes a sound wave propagating along one surface 11a (specifically, a Rayleigh wave), whether or not the modified layer 17 is exposed on the surface may be determined by comparing the time (measured time) it takes for the sound wave propagating along one surface 11a to actually propagate from the starting point (i.e., one of the four sound wave transmitting / receiving units 26a, 26b, 26c, 26d) to the ending point (i.e., one of the four sound wave transmitting / receiving units 26a, 26b, 26c, 26d) with a time threshold stored in memory 52b. Note that the sound wave transmitting / receiving unit 26a, 26b, 26c, or 26d that serves as the starting point of the sound wave may be the same as or different from the sound wave transmitting / receiving unit 26a, 26b, 26c, or 26d that serves as the ending point.

[0095] If the measured time is longer than this time threshold, the processor 52a determines that the modified layer 17 is exposed on the surface. This time threshold is, for example, the time (virtual time) that is assumed to be required for a sound wave propagating along one surface 11a of the wafer 11 from its starting point to its ending point when the modified layer 17 is not formed. Furthermore, if the sound wave transmitting and receiving units 26a, 26b, 26c, or 26d, which are the starting and ending points of the sound wave, are the same, the virtual time is the time that is assumed to be required for a sound wave propagating along one surface 11a of the wafer 11 to travel back and forth with the outer surface 11c as the turning point when the modified layer 17 is not formed.

[0096] Alternatively, if the reflected wave RW, which includes waves other than Rayleigh waves (for example, Lamb waves), becomes the received wave and the time required for the sound wave to propagate from the origin to the endpoint is known in advance, then whether or not the modified layer 17 is exposed on the surface may be determined by referring to a graph showing the change in the intensity of the received wave over time.

[0097] For example, in this graph showing the change over time, if a peak is observed at the point when the required time has elapsed since the transmission of the wave, the processor 52a determines that the modified layer 17 is exposed on the surface. Alternatively, the processor 52a may determine that the modified layer 17 is exposed on the surface if the intensity of this peak is greater than the intensity threshold stored in the memory 52b.

[0098] Alternatively, the determination of the positional characteristics of the modified layer 17 and / or whether the modified layer 17 is exposed on the surface may be made by comparing the virtual characteristics stored in memory 52b with the characteristics of the received wave actually received by at least one of the four sound wave transmitting / receiving units 26a, 26b, 26c, 26d in the sound wave transmitting / receiving process S2.

[0099] When sound waves propagate through the interior and / or surface of the wafer 11 and reach the modified layer 17, the cracks 17b and 17c vibrate, generating sound with a frequency different from that of the original sound wave (transmitted wave). The reflected wave RW or transmitted wave TW, which includes the newly generated sound, is then received as a received wave by the four sound wave transmitting and receiving units 26a, 26b, 26c, and 26d.

[0100] Therefore, in inspection step S3, prior to identifying the location of the modified layer 17 and determining whether or not the modified layer 17 is exposed on the surface, the processor 52a may confirm whether or not the modified layer 17 (specifically, cracks 17b, 17c) is formed by comparing the frequency of sound contained in the transmitted wave with the frequency of sound contained in the received wave.

[0101] However, in order to vibrate the cracks 17b and 17c and generate sound at a frequency different from the sound frequency contained in the transmitted wave, the intensity of the transmitted wave needs to be increased. Therefore, when checking whether or not the modified layer 17 (specifically, the cracks 17b and 17c) is formed, it is preferable to increase the intensity of the transmitted wave compared to when only the location of the modified layer 17 and / or whether or not the modified layer 17 is exposed on the surface is identified.

[0102] Furthermore, if the transmitted wave contains two or more Rayleigh waves with different frequencies, the depth of the modified layer 17 containing crack 17b (i.e., the distance from one surface 11a to the bottom of crack 17b) or the distance between one surface 11a and the modified layer 17 containing crack 17c (i.e., the distance from one surface 11a to the proximal end (upper end) of crack 17c) may be used to determine the location of the modified layer 17. For convenience, the depth and the distance will be collectively referred to as values ​​indicating the location of the modified layer 17 below.

[0103] Specifically, the penetration depth of Rayleigh waves, which are sound waves propagating across the surface of wafer 11, is proportional to the reciprocal of their frequency. Furthermore, even if the penetration depth is changed within a range smaller than the value indicating the location of the modified layer 17, the attenuation rate in wafer 11 (specifically, the value obtained by dividing the intensity of sound waves with a predetermined frequency included in the received wave by the intensity of sound waves with the same frequency included in the transmitted wave) remains approximately constant. On the other hand, if the penetration depth is changed within a range larger than the value indicating the location of the modified layer 17, the attenuation rate in wafer 11 changes significantly.

[0104] In other words, the specific penetration depth at which the attenuation rate in wafer 11 changes significantly corresponds to a value indicating the position of the modified layer 17. Therefore, by comparing the attenuation rates in wafer 11 for two or more Rayleigh waves with different frequencies, the value indicating the position of the modified layer 17 can be identified.

[0105] For example, if the first attenuation rate in wafer 11 for a Rayleigh wave of a first frequency (e.g., 2 MHz) and the second attenuation rate in wafer 11 for a Rayleigh wave of a second frequency (e.g., 20 MHz), which is greater than the first frequency, are approximately equal, the value indicating the position of the modified layer 17 can be determined to be greater than or equal to the first penetration depth for the Rayleigh wave of the first frequency (e.g., 2 mm) or less than or equal to the second penetration depth for the Rayleigh wave of the second frequency (e.g., 0.2 mm). Furthermore, if the first and second attenuation rates are significantly different, the value indicating the position of the modified layer 17 can be determined to be a value between the first and second penetration depths (e.g., 0.2 mm to 2 mm).

[0106] Furthermore, in the inspection step S3, an additional sound wave transmission and reception step similar to the sound wave transmission and reception step S2 may be performed to more accurately determine the value indicating the position of the modified layer 17, which has been identified to some extent, except that the frequency of the Rayleigh wave included in the transmitted wave is different. For example, if the value indicating the position of the modified layer 17 is determined to be a value between the first penetration depth and the second penetration depth, a sound wave transmission and reception step may be performed to calculate the third attenuation rate in the wafer 11 of a Rayleigh wave with a third frequency (e.g., 1 MHz) that is greater than the first frequency and less than the second frequency.

[0107] This allows us to determine whether the value indicating the location of the modified layer 17 is between the second penetration depth and the third penetration depth of the Rayleigh wave of the third frequency (e.g., 1 mm) (e.g., 0.2 mm to 1 mm) or between the third penetration depth and the first penetration depth (e.g., 1 mm to 2 mm). In other words, if the third attenuation rate is approximately equal to the first attenuation rate and significantly different from the second attenuation rate, we can determine that the value indicating the location of the modified layer 17 is between the second and third penetration depths. Also, if the third attenuation rate is significantly different from the first attenuation rate and approximately equal to the second attenuation rate, we can determine that the value indicating the location of the modified layer 17 is between the first and third penetration depths.

[0108] In the embodiment described above, the position of the modified layer 17 is identified and / or it is determined whether the modified layer 17 is exposed on the surface based on the characteristics of the sound waves (received waves) propagating through the inside and / or surface of the wafer 11. If the position of the modified layer 17 is deviated from the desired position and / or the modified layer 17 is not exposed on the surface, there is a risk that the wafer 11 cannot be divided with the desired processing quality.

[0109] In other words, identifying the location of the modified layer 17 and / or whether the modified layer 17 is exposed on the surface greatly affects the processing quality when the wafer 11 is divided. Therefore, according to the embodiment described above, it becomes possible to non-destructively and easily inspect whether a modified layer 17 suitable for ensuring processing quality when the wafer 11 is divided is formed on the wafer 11.

[0110] The embodiments described above are merely one aspect of the present invention, and the present invention is not limited to the embodiments described above. For example, in the processing inspection apparatus 2, the number of sound wave transmitting and receiving units is not limited to four, but may be 1 to 3 or 5 or more.

[0111] Furthermore, in the processing inspection apparatus 2, the sound wave transmitting and receiving unit may be provided in contact with the outer circumferential surface of the side wall of the frame 24a of the holding unit 24, rather than being built into the side wall of the frame 24a. In this case, for example, the transmitted wave is propagated to the wafer 11 via the side wall of the frame 24a, and the sound wave propagated from the wafer 11 to the side wall of the frame 24a becomes the received wave. In addition, in this case, a highly self-lubricating resin (for example, polyacetal resin (POM resin)) may be provided near the outer circumferential surface of the side wall and / or near the inner surface of the sound wave transmitting and receiving unit, and at least one of the holding unit 24 and the sound wave transmitting and receiving unit may be able to rotate independently of each other while the holding unit 24 and the sound wave transmitting and receiving unit are in contact.

[0112] Furthermore, in the processing inspection apparatus 2, the sound wave transmitting and receiving unit may be provided at a distance from the outer circumferential surface of the frame 24a of the holding unit 24, rather than being built into the side wall of the frame 24a. In this case, for example, the transmitted wave is propagated to the wafer 11 via a support member fixed to the other surface 11b of the wafer 11, and the sound wave propagated from the wafer 11 to the support member becomes the received wave. Moreover, in this case, at least one of the holding unit 24 and the sound wave transmitting and receiving unit may be rotatable independently of each other.

[0113] Furthermore, in the processing inspection apparatus 2, the sound wave transmitting and receiving unit may be provided in contact with the lower surface of the bottom wall of the frame 24a, rather than being built into the side wall of the frame 24a of the holding unit 24. In this case, for example, the transmitted wave is propagated to the wafer 11 via the bottom wall and side wall of the frame 24a, and the sound waves propagated from the wafer 11 to the side wall and bottom wall of the frame 24a become the received wave.

[0114] Furthermore, in the processing inspection apparatus 2, a sound wave transmitting and receiving unit may be provided so as to surround the porous plate 24b of the holding unit 24. Figure 8 is a schematic plan view showing an example of such a sound wave transmitting and receiving unit.

[0115] As shown in Figure 8, four sound wave transmitting and receiving units 54a, 54b, 54c, and 54d are housed in the side wall of the frame 24a of the holding unit 24, such that their respective arc-shaped upper surfaces are flush with the upper surface of the side wall of the frame 24a and the upper surface of the porous plate 24b. In other words, the four sound wave transmitting and receiving units 54a, 54b, 54c, and 54d are provided in contact with the holding unit 24 so as not to move relative to the holding unit 24.

[0116] Specifically, the four sound wave transmitting and receiving units 54a, 54b, 54c, and 54d are arranged along the outer circumference of a circular region included in the holding surface of the holding unit 54. That is, the four sound wave transmitting and receiving units 54a, 54b, 54c, and 54d are each provided along four non-overlapping circular arcs included in the outer circumference of this region.

[0117] Furthermore, in the processing inspection apparatus 2, a sound wave transmitting and receiving unit may be provided so as to be movable relative to the holding unit 24. Figure 9 is a schematic diagram showing an example of such a sound wave transmitting and receiving unit.

[0118] Above the holding portion 24 shown in Figure 9, a rectangular annular movable member 58 is provided. This movable member 58 has a pair of short portions 58a and 58b, each extending along the Y direction and facing each other, and a pair of long portions 58c and 58d, each extending along the X direction and facing each other, and connecting the ends of the pair of short portions 58a and 58b.

[0119] The distance between the pair of short sections 58a and 58b is greater than the outer diameter of the side wall of the frame 24a of the holding section 24. The distance between the pair of long sections 58c and 58d is approximately equal to, for example, the inner diameter of the side wall of the frame 24a of the holding section 24.

[0120] Furthermore, sound wave transmitting and receiving units 60a and 60b extending along the X direction are provided at the center of the lower surface of each of the pair of longitudinal sections 58c and 58d. Each sound wave transmitting and receiving unit 60a and 60b has, for example, at least one sound wave transmitter such as a contact-type or non-contact-type transmitting probe. Alternatively, each sound wave transmitting and receiving unit 60a and 60b may have a laser oscillator (transmitting laser oscillator) for emitting a laser beam capable of exciting ultrasonic waves onto the wafer 11 held on the holding surface of the holding section 24.

[0121] Furthermore, each sound wave transmitting / receiving unit 60a, 60b may have, in place of or in addition to the sound wave transmitter, a sound wave receiver such as, for example, at least one contact-type or non-contact-type receiving probe. Alternatively, each sound wave transmitting / receiving unit 60a, 60b may have, in place of or in addition to the transmitting laser oscillator, a laser oscillator (receiving laser oscillator) for emitting a laser beam for a probe used to read minute displacements in the wafer 11 held on the holding surface of the holding unit 24.

[0122] Furthermore, a moving mechanism 64 is connected to the moving member 58. This moving mechanism 64 includes, for example, a ball screw for moving the moving member 58 along the X direction and a ball screw for moving the moving member 58 along the Z direction. By operating this moving mechanism 64, the moving member 58 can be moved between the inspection position and the standby position.

[0123] The inspection position is the position of the movable member 58 to which the pair of sound wave transmitting and receiving units 60a and 60b are positioned such that the transmitted and received waves are sound waves that propagate or have propagated through the inside and / or surface of the wafer 11 held on the holding surface of the holding unit 24. In short, the inspection position is the position of the movable member 58 to which the pair of sound wave transmitting and receiving units 60a and 60b are in contact with or approach one surface 11a of the wafer 11, which is held with one surface 11a facing upwards.

[0124] Furthermore, the standby position is the position of the movable member 58 to which the pair of sound wave transmitting and receiving units 60a and 60b are positioned such that the transmitted wave and the received wave are sound waves that do not propagate or did not propagate inside and / or on the surface of the wafer 11 held on the holding surface of the holding unit 24. In short, the standby position is the position of the movable member 58 in which the holding unit 24 and the pair of sound wave transmitting and receiving units 60a and 60b do not overlap in the Z direction.

[0125] Furthermore, in the processing inspection device 2, a pair of sound wave transmitting and receiving units 60a and 60b may be provided so as to be able to move relative to each other independently with respect to the holding unit 24. That is, in the processing inspection device 2, instead of the moving member 58 and the moving mechanism 64, a first moving member on which a sound wave transmitting and receiving unit 60a is provided, a first moving mechanism for moving the first moving member, a second moving member on which a sound wave transmitting and receiving unit 60b is provided, and a second moving mechanism for moving the second moving member may be provided.

[0126] Furthermore, in the processing inspection apparatus 2, a pair of sound wave transmitting and receiving units 60a and 60b may be provided such that the transmitted and received waves propagate through other components in addition to the inside and / or surface of the wafer 11 held on the holding surface of the holding unit 24. That is, in the processing inspection apparatus 2, instead of the moving member 58 and the moving mechanism 64, the moving member and the moving mechanism may be provided such that the inspection position is when the pair of sound wave transmitting and receiving units 60a and 60b contact or approach the outer peripheral surface of the side wall of the frame 24a of the holding unit 24 or the lower surface of its bottom wall. Alternatively, in the processing inspection apparatus 2, instead of the moving member 58 and the moving mechanism 64, the moving member and the moving mechanism may be provided such that the inspection position is when the position contacts or approaches the support member fixed to the other surface 11b of the wafer 11.

[0127] Furthermore, if the reflected wave becomes the received wave, one of the pair of sound wave transmitting / receiving units 60a and 60b may be omitted in the processing inspection device 2. Also, in addition to the pair of sound wave transmitting / receiving units 60a and 60b, one or more other sound wave transmitting / receiving units may be provided in the processing inspection device 2. Furthermore, in the processing inspection device 2, a point-shaped, linear, annular, U-shaped, or C-shaped moving member may be provided instead of the rectangular tubular moving member 58.

[0128] Furthermore, in the processing inspection apparatus 2, a pair of sound wave transmitting and receiving units 60a and 60b may be provided such that the transmitted and received waves are sound waves that propagate locally within and / or on the surface of the wafer 11 held on the holding surface of the holding unit 24. For example, in the processing inspection apparatus 2, instead of the moving member 58 and the moving mechanism 64, the moving member and the moving mechanism may be provided so that the inspection position is a position where the transmitted and received waves are sound waves that propagate only within and / or near a specific dividing line 15 on the inside and / or surface of the wafer 11. Alternatively, in the processing inspection apparatus 2, instead of the moving member 58 and the moving mechanism 64, the moving member and the moving mechanism may be provided so that the inspection position is a position where the transmitted and received waves are sound waves that propagate only within and / or near a specific device 13 on the inside and / or surface of the wafer 11.

[0129] Furthermore, in the processing inspection apparatus 2, multiple sound wave transmitters included in the sound wave transmitting / receiving units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b may be associated with multiple sound wave receivers included in different or the same sound wave transmitting / receiving units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b on a one-to-one basis. That is, each of the multiple sound wave receivers may be capable of receiving only those sound waves transmitted from any one of the multiple sound wave transmitters that have propagated inside and / or on the surface of the wafer 11.

[0130] Alternatively, in the processing inspection apparatus 2, the multiple sound wave transmitters included in the sound wave transmitting / receiving units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b and the multiple sound wave receivers included in the sound wave transmitting / receiving units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b may be associated with each other in an interchangeable manner. That is, each of the multiple sound wave receivers may be capable of receiving sound waves transmitted from each of the multiple sound wave transmitters that have propagated inside and / or on the surface of the wafer 11.

[0131] Furthermore, in the processing inspection apparatus 2, the sound wave transmitting and receiving units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b may have a sound wave transmitting and receiving unit that transmits a sound wave that propagates inside and / or on the surface of the wafer 11, and receives this sound wave as a received wave, instead of a sound wave transmitter and / or receiver.

[0132] This sound wave transceiver is, for example, at least one contact-type or non-contact-type transmitting / receiving probe. Alternatively, the sound wave transceiver may have a transmitting laser oscillator and a receiving laser oscillator.

[0133] Furthermore, if multiple sound wave transceivers are included in the sound wave transceiver units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b, each sound wave transceiver may be used independently of the other sound wave transceivers, or the multiple sound wave transceivers may be used interchangeably with each other. That is, each sound wave transceiver may be capable of receiving only reflected waves originating from itself as received waves, or it may be capable of receiving not only reflected waves originating from itself but also reflected waves or transmitted waves originating from other sound wave transceivers as received waves.

[0134] Furthermore, in the processing inspection apparatus 2, multiple transmitted waves transmitted from multiple sound wave transmitters included in the sound wave transmitting / receiving units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, and 60b may be combined. Figures 10(A), 10(B), and 10(C) respectively schematically show how multiple transmitted waves are combined.

[0135] Figure 10(A) shows how multiple sound wave transmitters 66a, 66b, 66c, 66d, 66e, 66f, and 66g, arranged along a predetermined alignment direction, transmit waves sequentially at equal time intervals from the transmitters at both ends (i.e., sound wave transmitters 66a and 66g) toward the transmitter in the center (i.e., sound wave transmitter 66d). In this case, multiple sound waves can be combined so that they are focused at a focusing point FP located in a direction perpendicular to the alignment direction as viewed from sound wave transmitter 66d.

[0136] Figure 10(B) shows how multiple sound wave transmitters 68a, 68b, 68c, 68d, 68e, 68f, 68g, 68h, 68i, 68j, 68k, and 68l, arranged along a predetermined alignment direction, transmit waves simultaneously. In this case, multiple sound waves can be combined to form a wavefront WF1 whose direction of propagation is perpendicular to the alignment direction.

[0137] Figure 10(C) shows how multiple sound wave transmitters 68a, 68b, 68c, 68d, 68e, 68f, 68g, 68h, 68i, 68j, 68k, and 68l, arranged along a predetermined alignment direction, transmit waves sequentially at equal time intervals from one end (i.e., sound wave transmitter 68a) to the other end (i.e., sound wave transmitter 68l). In this case, multiple sound waves can be combined to form a wavefront WF2 whose direction of propagation is inclined from the direction perpendicular to the alignment direction. This inclined direction can be adjusted by changing the time interval when transmitting the multiple sound wave transmitters.

[0138] Furthermore, the sound wave transmission / reception process S2 may be performed during the modified layer formation process S1, rather than after it. In this case, the focusing point FP shown in Figure 10(A) may be changed over time to follow the focusing point where the laser beam LB is focused, or the modified layer formation process S1 and the sound wave transmission / reception process S2 may be performed so that the focusing point where the laser beam LB is focused is positioned in the direction of propagation (i.e., the inclined direction mentioned above) when viewed from the wavefront WF2 shown in Figure 10(C).

[0139] Furthermore, the inspection step of identifying the location of the modified layer 17 on the wafer 11 and / or determining whether the modified layer 17 is exposed on the surface of the wafer 11 may be performed after the modified layer 17 has been formed along two or more parallel division lines 15. Figure 11 is a schematic flowchart showing an example of a processing inspection method that includes the inspection step performed in this manner.

[0140] In the inspection method shown in Figure 11, first, the focal point where the laser beam LB is focused is moved along the first planned division line 15 (first planned division line) set on the wafer 11 in order to form a modified layer 17 (first modified layer) along the first planned division line (first modified layer formation step S1'). Then, the sound wave transmitting unit transmits a transmitted wave (first transmitted wave) which will be a sound wave (first sound wave) propagating through the inside and / or surface of the wafer 11, and the sound wave receiving unit receives the first sound wave as a received wave (first received wave) (first sound wave transmission and reception step S2').

[0141] Furthermore, the first sound wave transmission / reception process S2' may be performed during the first modified layer formation process S1', rather than after it. Also, since the first modified layer formation process S1' and the first sound wave transmission / reception process S2' are performed in the same manner as the modified layer formation process S1 and the sound wave transmission / reception process S2 described above, their details are omitted.

[0142] After the first sound wave transmission / reception process S2', the focal point where the laser beam LB is focused is moved along the second planned division line so as to form a modified layer 17 (second modified layer) along a specific planned division line 15 (second planned division line) set on the wafer 11 so as to be parallel to the first planned division line (second modified layer formation process S1''). Then, the sound wave transmission unit transmits a transmission wave (second transmission wave) which will be a sound wave (second sound wave) propagating through the inside and / or surface of the wafer 11, and the sound wave receiving unit receives the second sound wave as a received wave (second received wave) (second sound wave transmission / reception process S2'').

[0143] Furthermore, the second sound wave transmission / reception process S2'' may be performed during the second modified layer formation process S1'', rather than after it. Also, the second modified layer formation process S1'' and the second sound wave transmission / reception process S2'' are performed in the same manner as the modified layer formation process S1 and the sound wave transmission / reception process S2 described above.

[0144] However, if the reflected wave RW becomes the second received wave, this second received wave is a superposition of a sound wave whose characteristics have been altered due to reflection from either the first or second modified layer, and a sound wave whose characteristics have been altered due to transmission through one layer and then reflection from the other. Therefore, in this case, the second received wave will have a greater intensity and a longer duration from the start to the end of reception compared to the first received wave.

[0145] Furthermore, when the transmitted wave TW becomes the second received wave, this second received wave is a sound wave whose characteristics have changed due to transmission through the first and second modified layers. Therefore, in this case, the intensity of the second received wave will be lower than that of the first received wave.

[0146] Furthermore, if a crack 17b appearing on one surface 11a of the wafer 11 is included in the second modified layer, the sound wave (specifically, a Rayleigh wave) propagating along the surface 11a of the wafer 11 is received as a second received wave at a time delayed from the time at which it is received as a first received wave.

[0147] Following the second sound wave transmission / reception process S2'', the positions of the first and second modified layers are determined based on the characteristics of the first and second received waves, and / or it is determined whether the first and second modified layers are exposed on the surface (inspection process S3'). The determination of the position of the first modified layer and whether the first modified layer is exposed on the surface is carried out in the same manner as the determination of the position of the modified layer 17 and whether the modified layer 17 is exposed on the surface in the inspection process S3 described above, so the details of these are omitted.

[0148] Furthermore, the position of the second modification layer is determined, for example, based on the time it takes for sound waves to actually originate from the sound wave transmitting / receiving units 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b, be reflected by the modification layer 17, and then propagate to the same or another sound wave transmitting / receiving unit 26a, 26b, 26c, 26d, 54a, 54b, 54c, 54d, 60a, 60b. This time corresponds, for example, to the period from the start of transmission of the second transmitted wave to the start of reception of the second received wave, or to the period from the end of transmission to the end of reception.

[0149] Furthermore, whether or not the second modified layer is exposed on the surface is determined, for example, by comparing the difference between the intensity of the first received wave and the intensity of the second received wave with a threshold value stored in memory 52b. Specifically, if the reflected wave RW is the second received wave, the processor 52a determines that the second modified layer is exposed on the surface (specifically, one of its surfaces 11a) if the value obtained by subtracting the intensity of the first received wave from the intensity of the second received wave is greater than the threshold value for the difference in intensity for the reflected wave RW stored in memory 52b. On the other hand, if the transmitted wave TW is the second received wave, the processor 52a determines that the second modified layer is exposed on the surface if the value obtained by subtracting the intensity of the second received wave from the intensity of the first received wave is greater than the threshold value for the difference in intensity for the transmitted wave TW stored in memory 52b.

[0150] Alternatively, if the second received wave includes a sound wave propagating across one surface 11a (specifically, a Rayleigh wave), whether or not the second modified layer is exposed on the surface may be determined based on whether or not this sound wave is received as the second received wave at a time delayed from the time it is received as the first received wave. That is, if the timing at which this sound wave is received as the second received wave is delayed from the timing at which it is received as the first received wave, the processor 52a determines that the second modified layer is exposed on the surface.

[0151] Furthermore, if the inspection step S3' is performed after the modified layer 17 has been formed along three or more parallel planned division lines 15, that is, after the second sound wave transmission / reception step S2'' and before the inspection step S3', the focal point where the laser beam LB is focused is moved along the third planned division line so as to form a modified layer 17 (third modified layer) along a specific planned division line 15 (third planned division line) set on the wafer 11 so as to be parallel to the first and second planned division lines. Then (third modified layer formation process), when the sound wave transmitting unit transmits a transmission wave (third transmission wave) that becomes a sound wave (third sound wave) propagating inside and / or on the surface of the wafer 11, and the sound wave receiving unit receives the third sound wave as a reception wave (third reception wave) (third sound wave transmission and reception process), in inspection step S3', it may be determined whether or not the second modified layer is exposed on the surface of the wafer 11 by comparing the difference in characteristics between the first reception wave and the second reception wave, and the difference in characteristics between the second reception wave and the third reception wave.

[0152] Specifically, when the reflected wave RW is the first, second, and third received wave, if the value obtained by subtracting the intensity of the first received wave from the intensity of the second received wave is significantly smaller than the value obtained by subtracting the intensity of the second received wave from the intensity of the third received wave, the processor 52a determines that the second modified layer is not exposed on the surface (specifically, one of its surfaces 11a). On the other hand, when the transmitted wave TW is the first, second, and third received wave, if the value obtained by subtracting the intensity of the second received wave from the intensity of the first received wave is significantly smaller than the value obtained by subtracting the intensity of the third received wave from the intensity of the second received wave, the processor 52a determines that the second modified layer is not exposed on the surface (specifically, one of its surfaces 11a).

[0153] Furthermore, in the present invention, the wafer 11, which is integrated with the ring frame via a support member fixed to one surface 11a, may be processed as a workpiece and inspected as an object to be inspected. In this case, the wafer 11 may be carried to the holding surface of the holding part 24 via the support member so that the other surface 11b faces upward. In this case, the modified layer 17 may be formed in the modified layer formation step S1 by irradiating the wafer 11 with a laser beam LB from the other surface 11b side rather than from the one surface 11a side.

[0154] Furthermore, in the present invention, grooves may be formed on the wafer 11 as the starting point for division instead of the modified layer 17. That is, the inspection apparatus of the present invention may be equipped with a cutting unit having a cutting blade for forming grooves as the starting point for division on the wafer 11 held on the holding surface of the holding unit 24, instead of the laser irradiation unit 42. Also, the inspection method of the present invention may be equipped with a groove forming step in which the contact point (processing point) between the cutting blade and the wafer 11 is moved along the planned division line 15 so as to form grooves along the planned division line 15, instead of the modified layer forming step S1.

[0155] Furthermore, the structures and methods of the embodiments described above can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0156] 2: Laser processing equipment 4: Base 6: Horizontal movement mechanism 8: Guide rail 10: Y-direction moving plate 11: Wafer (11a: Front surface, 11b: Back surface, 11c: Outer edge surface) 12: Screw shaft 13: Device 14: Motor 15: Planned division line 16: Guide rail 17: Modified layer (17a: Modified section) (17b: crack (exposed crack), 17c: crack (non-exposed crack)) 18: X-direction moving plate 20: Screw shaft 22: Motor 24: Holding part (24a: frame body, 24b: porous plate) 26a, 26b, 26c, 26d: Sound wave transceiver 30:Support structure 32: Vertical movement mechanism 34: Guide rail 36: Z-direction movement plate 38: Motor 40: Support 42: Laser irradiation area 44: Head 46: Housing 48: Imaging Department 50: Interface section 52: Controller (52a: Processor, 52b: Memory) 54a, 54b, 54c, 54d: Sound wave transceiver 58: Moving member (58a, 58b: short side, 58c, 58d: long side) 60a, 60b: Sound wave transceiver 64: Movement mechanism 66a, 66b, 66c, 66d, 66e, 66f, 66g: Sound wave transmitters 68a, 68b, 68c, 68d, 68e, 68f, 68g, 68h, 68i, 68j, 68k, 68l: Sound wave transmitter

Claims

1. A division starting point formation step involves moving a processing point along a division starting point that is set along a division starting line on the object to be inspected, A sound wave transmission and reception process, performed after or during the division starting point formation process, in which a sound wave transmission unit transmits a transmission wave that propagates through the inside and / or surface of the object under inspection, and a sound wave receiving unit receives the sound wave as a received wave, An inspection step of identifying the position of the division starting point and / or determining whether the division starting point is exposed on the surface, based on the characteristics of the received wave. An inspection method that includes the following features.

2. If the sound wave receiving unit is provided to receive the sound wave reflected due to the presence of the division starting point, then in the inspection step, if the intensity of the received wave is greater than a first threshold, it is determined that the division starting point is exposed on the surface. The inspection method according to claim 1, wherein, if the sound wave receiving unit is provided to receive the sound wave that has passed through the division starting point, it is determined that the division starting point is exposed on the surface if the intensity of the received wave is less than a second threshold in the inspection step.

3. The inspection method according to claim 1, wherein the inspection step involves confirming that the division starting point is formed by comparing the frequency of sound contained in the transmitted wave with the frequency of sound contained in the received wave, identifying the position of the division starting point, and / or determining whether the division starting point is exposed on the surface.

4. The transmitted wave includes a Rayleigh wave, The inspection method according to claim 1, wherein the inspection step involves comparing the measured time required for the sound wave to actually propagate from the sound wave transmitting unit to the sound wave receiving unit in the sound wave transmission and reception step with the hypothetical time that is assumed to be required for the sound wave to propagate from the sound wave transmitting unit to the sound wave receiving unit when the division point is not formed, thereby determining whether or not the division point is exposed on the surface.

5. The transmitted wave includes waves other than Rayleigh waves, The sound wave receiving unit is provided to receive the sound waves reflected due to the presence of the division origin, The time required for the sound wave to propagate from the sound wave transmitting unit to the sound wave receiving unit is known in advance. The inspection method according to claim 1, wherein in the inspection step, if a peak is observed in a graph showing the change in intensity of the received wave over time at a time after the transmitted wave has been transmitted, or if the intensity of the peak is greater than a threshold, it is determined that the splitting starting point is exposed on the surface.

6. The inspection method according to claim 1, wherein in the inspection step, the position of the division starting point is identified and / or the division starting point is determined to be exposed on the surface by comparing a hypothetical characteristic assumed to be the characteristic of the received wave in the state in which the division starting point is formed with the characteristic of the received wave actually received by the sound wave receiving unit in the sound wave transmission and reception step.

7. The transmitted wave includes two or more Rayleigh waves with different frequencies. The inspection method according to claim 1, wherein in the inspection step, the depth of the division starting point exposed on the surface, or the distance between the division starting point not exposed on the surface and the surface, is identified as the position of the division starting point by comparing the attenuation rates of the two or more Rayleigh waves in the object under inspection.

8. The inspection method according to claim 1, wherein the transmitted wave includes a Lamb wave.

9. A first division starting point formation step involves moving a processing point along the first division starting point to form a first division starting point along the first division starting line set on the object to be inspected, A first sound wave transmission and reception step, performed after or during the first division starting point formation step, in which a sound wave transmission unit transmits a first transmission wave that becomes a first sound wave propagating through the inside and / or surface of the object under inspection, and a sound wave receiving unit receives the first sound wave as a first reception wave, A second division starting point formation step is performed after the first sound wave transmission / reception step, in which the processing point is moved along the second division starting point so as to form a second division starting point along the second division starting point which is set on the workpiece to be inspected so as to be parallel to the first division starting point, A second sound wave transmission and reception step, performed after or during the second division starting point formation step, in which the sound wave transmission unit transmits a second transmission wave that propagates through the inside and / or surface of the object under inspection, and the sound wave receiving unit receives the second sound wave as a second reception wave, An inspection step of identifying the respective positions of the first division starting point and the second division starting point based on the first received wave and the second received wave, and / or determining whether the respective first division starting point and the second division starting point are exposed on the surface, An inspection method that includes the following features.

10. A third division starting point formation step is performed after the second sound wave transmission / reception step, in which the processing point is moved along the third division starting point so as to form a third division starting point along the third division starting point which is set on the workpiece to be inspected so as to be parallel to the first division starting point and the second division starting point, The invention further comprises a third sound wave transmission and reception step, performed after or during the third division starting point formation step, in which the sound wave transmission unit transmits a third transmission wave that becomes a third sound wave propagating through the inside and / or surface of the object under inspection, and the sound wave receiving unit receives the third sound wave as a third reception wave, The inspection method according to claim 9, wherein in the inspection step, the second division starting point is determined to be exposed on the surface by comparing the difference in characteristics between the first received wave and the second received wave and the difference in characteristics between the second received wave and the third received wave.

11. The sound wave transmitting unit has a plurality of sound wave transmitters, The inspection method according to any one of claims 1 to 10, wherein the sound wave receiving unit has a plurality of sound wave receivers, each for receiving only those sound waves transmitted from any one of the plurality of sound wave transmitters that have propagated through the inside and / or surface of the object to be inspected.

12. The sound wave transmitting unit has a plurality of sound wave transmitters, The inspection method according to any one of claims 1 to 10, wherein the sound wave receiving unit has a plurality of sound wave receivers for receiving sound waves transmitted from each of the plurality of sound wave transmitters among the sound waves propagated inside and / or on the surface of the object to be inspected.

13. The inspection method according to any one of claims 1 to 10, wherein the sound wave transmitting unit comprises a plurality of sound wave transmitters capable of transmitting a plurality of sound waves that are focused at a desired position inside the object under inspection or that form a wavefront perpendicular to a desired direction.

14. The inspection method according to claim 13, wherein the plurality of sound wave transmitters change their desired positions over time to follow the processing point moving inside the object under inspection, or transmit the plurality of sound waves such that the processing point moving inside the object under inspection is positioned in a desired direction with respect to the wavefront.

15. A holding part for holding an object to be inspected, on a holding surface, where the division starting point is formed, A sound wave transmitting unit for transmitting a transmission wave that becomes a sound wave propagating through the inside and / or surface of the object under inspection held on the holding surface, A sound wave receiving unit for receiving sound waves that have propagated through the inside and / or surface of the object under inspection as received waves, The device comprises a holding unit, a sound wave transmitting unit, and a controller capable of communicating with the sound wave transmitting unit, The controller is, A memory for storing data indicating the received wave, An inspection apparatus comprising: a processor that identifies the position of the division starting point and / or determines whether the division starting point is exposed on the surface, based on the characteristics of the received wave.

16. The inspection apparatus according to claim 15, wherein the sound wave transmitting unit and the sound wave receiving unit do not move relative to the holding unit.

17. The inspection apparatus according to claim 15 or 16, wherein the sound wave transmitting unit and the sound wave receiving unit are provided in contact with the holding unit.

18. The inspection apparatus according to claim 15 or 16, wherein the sound wave transmitting unit and the sound wave receiving unit are arranged along the outer circumference of a rectangular region included in the holding surface in a plan view.

19. The inspection apparatus according to claim 15 or 16, wherein the sound wave transmitting unit and the sound wave receiving unit are arranged along the outer circumference of a circular region included in the holding surface in a plan view.

20. A movable member on which the sound wave transmitting unit and the sound wave receiving unit are provided, A moving mechanism for moving the moving member between an inspection position in which the sound wave transmitting unit and the sound wave receiving unit are positioned such that the transmitting wave and the receiving wave are, respectively, sound waves that propagate or have propagated through the inside and / or surface of the object under inspection held on the holding surface, and a standby position in which the sound wave transmitting unit and the sound wave receiving unit are positioned such that the transmitting wave and the receiving wave are sound waves that do not propagate or have not propagated through the inside and / or surface of the object under inspection held on the holding surface, The inspection apparatus according to claim 15, further comprising:

21. The sound wave transmitting unit has a plurality of sound wave transmitters, The inspection apparatus according to claim 15, 16, or 20, wherein the sound wave receiving unit has a plurality of sound wave receivers, each for receiving only those sound waves transmitted from any one of the plurality of sound wave transmitters that have propagated through the inside and / or surface of the object under inspection.

22. The sound wave transmitting unit has a plurality of sound wave transmitters, The inspection apparatus according to claim 15, 16, or 20, wherein the sound wave receiving unit has a plurality of sound wave receivers for receiving sound waves transmitted from each of the plurality of sound wave transmitters among the sound waves propagated through the inside and / or surface of the object to be inspected.

23. The inspection apparatus according to claim 15, 16, or 20, wherein the sound wave transmitting unit comprises a plurality of sound wave transmitters capable of transmitting a plurality of sound waves that are focused at a desired position inside the object under inspection or that form a wavefront perpendicular to a desired direction.

24. The inspection apparatus according to claim 15, 16, or 20, further comprising a laser irradiation unit capable of irradiating a laser beam into the interior of the object to be inspected, which is held on the holding surface, to form a modified layer as the starting point for splitting and a crack extending to penetrate the modified layer.

25. The inspection apparatus according to claim 15, 16, or 20, further comprising a cutting section having a cutting blade for forming a groove as the starting point for division in the object to be inspected which is held on the holding surface.

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