Method and apparatus for inspecting workpieces

Abstract

To provide a workpiece inspection method and inspection device with which it is possible to determine a peeling layer formed in the inside of an ingot, without lowering productivity, and without being affected by saw marks.SOLUTION: The workpiece inspection method comprises: a peeling layer formation step for forming, in the inside of a workpiece 100, a peeling layer 110 that is composed of a modified layer parallel to a top face 101 and a crack extending from the modified layer; an irradiation step for irradiating the entire top face 101 of the workpiece 100 in which the peeling layer 110 has been formed, with light 25 of a wavelength that passes through the workpiece 100 and is reflected at a crack of the peeling layer 110, after the peeling layer formation step is carried out; a light reception step for receiving reflected light 35 having been irradiated and reflected by a crack in the irradiation step; and a determination step for determining the state of the peeling layer 110 on the basis of the intensity of reflected light 35 having been received in the light reception step.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an inspection method and an inspection apparatus for a workpiece made of single crystal silicon. [Background Art]

[0002] A wire saw is known as means for cutting out wafers from silicon ingots, compound semiconductor ingots, and the like. In a wire saw, a wire row is formed by winding a large number of cutting wires around a plurality of rollers, and cutting is performed at the wire position by feeding the cutting wires into the ingot (see, for example, Patent Document 1). However, the kerf loss of a wire saw is relatively large at around 300 μm, and it is necessary to perform lapping, etching, and polishing to flatten the surface after cutting, so the amount of material used as wafers is only about one-third of the original ingot, which has the problem of poor productivity.

[0003] Accordingly, a technique has been devised in which a laser beam is irradiated onto an ingot to form a separation layer composed of a modified portion and cracks inside the ingot, and a wafer is separated from the ingot starting from this separation layer (see Patent Document 2). This makes it possible to significantly reduce material loss compared to wire saws, but it has been found that when separation is performed starting from the separation layer, there are cases where separation cannot be performed due to insufficient formation of the separation layer or insufficient separation treatment (such as application of ultrasonic waves).

[0004] Accordingly, a method for detecting a separation layer formed inside an ingot by irradiating light onto the ingot has been devised in order to identify regions where no separation layer has been formed and perform additional processing and separation treatment (see Patent Documents 3 and 4). [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 09-262826 [Patent Document 2] Japanese Patent Publication No. 2022-025566 [Patent Document 3] Japanese Patent Publication No. 2021-068819 [Patent Document 4] Japanese Patent Publication No. 2018-147928 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the method described in Patent Document 3, the focusing lens and the delamination layer detection unit are arranged adjacent to each other in a direction parallel to the processing feed direction, resulting in areas that cannot be detected when laser processing is complete. Consequently, even though processing is finished, it becomes necessary to overrun the focusing lens and the delamination layer detection unit to detect the delamination layer, which could lead to a decrease in productivity as the ingot diameter increases. Furthermore, in the method described in Patent Document 4, the state of the delamination layer formed inside the ingot is determined using the so-called magic mirror principle, but this method has the problem of being easily affected by saw marks on the ingot surface.

[0007] The present invention has been made in view of the above problems, and its objective is to provide a workpiece inspection method and inspection apparatus that can determine the delamination layer formed inside the ingot without reducing productivity and without being affected by saw marks. [Means for solving the problem]

[0008] To solve the above-mentioned problems and achieve the objective, the present invention provides a method for inspecting a workpiece made of single-crystal silicon manufactured such that specific crystal planes included in the crystal plane {100} are exposed on the upper and lower surfaces, respectively, comprising: a delamination layer formation step in which a laser beam with a wavelength that is transparent to the workpiece is focused at a depth corresponding to the thickness of the wafer being manufactured from the upper surface of the workpiece, and the laser beam is irradiated while the focus point and the workpiece are moved relative to each other in the processing feed direction to form a modified layer parallel to the upper surface and cracks extending from the modified layer inside the workpiece; an irradiation step in which, after performing the delamination layer formation step, light with a wavelength that penetrates the workpiece and is reflected by the cracks in the delamination layer is irradiated onto the entire upper surface of the workpiece on which the delamination layer has been formed; a light receiving step in which the reflected light irradiated in the irradiation step and reflected by the cracks is received; and a determination step in which the state of the delamination layer is determined based on the intensity of the reflected light received in the light receiving step.

[0009] In the determination step, it is determined whether adjacent cracks in the delamination layer are connected based on whether the reflected light intensity is greater than a first predetermined value. If it is determined in the determination step that adjacent cracks in the delamination layer are connected, a further delamination step may be performed in which an external force is applied to the workpiece to delaminate the wafer from the workpiece, starting from the delamination layer.

[0010] After performing the delamination layer formation step, a delamination step may be further performed in which an external force is applied to the workpiece to delaminate the wafer from the workpiece starting from the delamination layer. If the wafer cannot be delaminated from the workpiece in the delamination step, the irradiation step, the light receiving step, and the determination step may be performed.

[0011] In this determination step, it may be determined whether the wafer has delaminated from the workpiece starting from the delamination layer, based on whether the reflected light intensity is greater than a second predetermined value which is greater than a first predetermined value which is a criterion for determining whether adjacent cracks in the delamination layer are connected and formed together.

[0012] The peel layer formation step involves the focusing point of the laser beam and the workpiece. Parallel to the upper surface of the workpiece and Crystal orientation <100> Specific crystal orientations included A laser beam irradiation step is performed alternately to irradiate the workpiece while moving along a direction parallel to the workpiece, thereby forming a modified layer parallel to the upper surface and cracks extending from the modified layer inside the workpiece; and an indexing feed step is performed to relatively index and feed the workpiece and the focusing point of the laser beam in a direction perpendicular to the direction in which the modified layer was formed in the laser beam irradiation step, thereby forming multiple modified layers and a peeling layer containing cracks inside the workpiece.

[0013] The light irradiated in the irradiation step may be irradiated onto the upper surface of the workpiece at a predetermined angle of incidence from a direction parallel to a plane perpendicular to the upper surface of the workpiece, including the processing feed direction.

[0014] To solve the above-mentioned problems and achieve the objective, the present invention provides an inspection device for inspecting a delamination layer formed inside a workpiece made of single-crystal silicon manufactured such that specific crystal planes included in the crystal plane {100} are exposed on the upper and lower surfaces, respectively, by irradiating the workpiece with a laser beam of a penetrating wavelength from the upper surface side, thereby inspecting a delamination layer formed inside the workpiece consisting of a modified layer and cracks extending from the modified layer, the inspection device comprising: a holding table that holds the workpiece with its upper surface exposed; a light source that irradiates the entire upper surface of the workpiece held on the holding table with light of a wavelength that penetrates the workpiece and is reflected by the cracks; a light receiving unit that receives reflected light irradiated onto the entire upper surface of the workpiece by the light source and reflected by the cracks contained in the delamination layer; and a determination means that determines the state of the delamination layer based on the reflected light intensity received by the light receiving unit.

[0015] The determination means may determine whether adjacent cracks in the delamination layer are connected or not based on whether the reflected light intensity is greater than a first predetermined value.

[0016] The determining means may determine whether a wafer is peeled from the workpiece starting from the peeling layer based on whether the reflected light intensity is greater than a second predetermined value, which is larger than a first predetermined value that serves as a determination criterion for whether adjacent cracks of the peeling layer are connected to each other.

[0017] The workpiece is Parallel to the upper surface of the workpiece and crystal orientation <100> Specific crystal orientations included A modified layer parallel to the upper surface and a peeling layer including cracks extending from the modified layer are formed by irradiating a laser beam along a direction parallel to said crystal orientation, and the light source may be disposed at a position where it can irradiate light onto the upper surface of the workpiece at a predetermined incident angle from a direction parallel to a plane perpendicular to the upper surface of the workpiece that includes the processing feed direction which is the direction the laser beam is irradiated.

[0018] There may be at least two light sources. Effects of the Invention

[0019] According to the present invention, light having a wavelength that transmits through the workpiece (Si ingot) and is reflected by the peeling layer (cracks) is irradiated onto the entire upper surface of the workpiece, and the intensity of the reflected light reflected from the peeling layer is observed to determine the state of the peeling layer inside the workpiece. Since the state of the peeling layer can be determined only by irradiating the entire upper surface of the workpiece once, the peeling layer can be determined in a short time without reducing productivity regardless of the size of the workpiece. In addition, according to the present invention, based on the intensity of the reflected light, the formation state of the peeling layer, more specifically, whether adjacent cracks are connected to each other, and whether the connected cracks have expanded to separate the ingot side and the wafer side of the workpiece can be determined, so the state of the peeling layer can be determined without being affected by saw marks. Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a perspective view showing an example of a workpiece that is an inspection target of the workpiece inspection method and inspection apparatus according to the first embodiment. [Figure 2] FIG. 2 is a top view showing the workpiece of FIG. 1. [Figure 3] FIG. 3 is a flowchart showing the processing procedure of the workpiece inspection method according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view illustrating the peeling layer forming step of FIG. 3. [Figure 5] FIG. 5 is a perspective view illustrating the peeling layer forming step of FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view illustrating a configuration example of the inspection apparatus according to the first embodiment and an example of the irradiation step and the light receiving step of FIG. 3. [Figure 7] FIG. 7 is a cross-sectional view illustrating another configuration example of the inspection apparatus according to the first embodiment and another example of the irradiation step and the light receiving step of FIG. 3. [Figure 8] FIG. 8 is a diagram illustrating the determination step of FIG. 3. [Figure 9] FIG. 9 is a plan view showing an example of the determination step of FIG. 3. [Figure 10] FIG. 10 is a perspective view illustrating the peeling step of FIG. 3. [Figure 11] FIG. 11 is a perspective view illustrating the peeling step of FIG. 3. [Figure 12] FIG. 12 is a flowchart showing the processing procedure of the workpiece inspection method according to the second embodiment. MODES FOR CARRYING OUT THE INVENTION

[0021] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily conceived by a person skilled in the art and those that are substantially identical. Furthermore, the configurations described below can be combined as appropriate. Various omissions, substitutions, or alterations in the configuration can be made without departing from the scope of the gist of the present invention.

[0022] [First Embodiment] A workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1 of the present invention will be described based on the drawings. Figure 1 is a perspective view showing an example of a workpiece 100 that is the object of inspection by the workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1. Figure 2 is a top view showing the workpiece 100 of Figure 1. As shown in Figure 1, the workpiece 100 is a Si (silicon) ingot made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the upper surface 101 and the lower surface 102, respectively. As shown in Figures 1 and 2, in Embodiment 1, the workpiece 100 is formed in a cylindrical shape overall and has a circular upper surface 101 with a specific crystal plane included in the crystal plane {100} as a flat surface, a circular lower surface 102 on the opposite side of the upper surface 101 with the same specific crystal plane as the upper surface 101 as a flat surface, and a circumferential surface 103 located between the upper surface 101 and the lower surface 102. In Embodiment 1, the upper surface 101 and the lower surface 102 are flat surfaces of a specific crystal plane (100) included in the crystal plane {100}, as shown in Figure 2. However, the present invention is not limited to this, and crystal planes (010) or (001) may also be flat surfaces.

[0023] As shown in Figures 1 and 2, a flat rectangular orientation flat 104 is formed on the circumferential surface 103 of the workpiece 100. In Embodiment 1, as shown in Figure 2, the orientation flat 104 is formed parallel to the crystal plane (011) at a position where the central axis 105 of the workpiece 100 is in the direction of the crystal orientation

[0011] . However, the workpiece 100 is not limited to this in the present invention, and instead of the orientation flat 104, a notch extending in the axial direction may be formed on the circumferential surface 103 at a similar position.

[0024] Next, this specification will describe a method for inspecting a workpiece according to Embodiment 1 with reference to the drawings. Figure 3 is a flowchart showing the processing procedure of the method for inspecting a workpiece according to Embodiment 1. The method for inspecting a workpiece according to Embodiment 1 is a method for inspecting a workpiece 100, and comprises a peeling layer formation step 1001, an irradiation step 1002, a light receiving step 1003, a determination step 1004, and a peeling step 1006.

[0025] Figures 4 and 5 are a cross-sectional view and a perspective view illustrating the delamination layer formation step 1001 of Figure 3, respectively. As shown in Figures 4 and 5, the delamination layer formation step 1001 involves positioning the focal point 59 of a laser beam 58 with a wavelength that is transparent to the workpiece 100 at a depth 120 corresponding to the thickness of the wafer to be manufactured, from the upper surface 101 of the workpiece 100, and irradiating the workpiece 100 with the laser beam 58 while relatively moving the focal point 59 and the workpiece 100 in the processing feed direction, thereby forming a delamination layer 110 inside the workpiece 100 that includes a modified layer parallel to the upper surface 101 and cracks extending from the modified layer.

[0026] In Embodiment 1, the peel layer formation step 1001 is performed by the laser processing apparatus 50 shown in Figures 4 and 5. As shown in Figures 4 and 5, the laser processing apparatus 50 includes a holding table 51 that holds the workpiece 100 on a holding surface 52, an oscillator 53, an output adjustment unit 54, a branching unit 55, a mirror 56, a light concentrator 57, a moving unit (not shown), and a control unit (not shown).

[0027] The holding table 51 is a chuck table that, for example, holds the workpiece 100 with its upper surface 101 exposed on the holding surface 52 and holds it by suction from the lower surface 102. The oscillator 53 emits a laser beam 58 with a wavelength that is penetrating to the workpiece 100. The output adjustment unit 54 adjusts the output of the laser beam 58 emitted by the oscillator 53. The branching unit 55 branches the laser beam 58 whose output has been adjusted by the output adjustment unit 54 into multiple beams (five in the example shown in Figure 4) at predetermined intervals in the Y-axis direction. The mirror 56 reflects the multiple laser beams 58 branched by the branching unit 55 and changes the optical axis direction. The concentrator 57 focuses the multiple laser beams 58 reflected by the mirror 56 and irradiates the workpiece 100 with them. The moving unit moves the holding table 51 and the workpiece 100 held on the holding table 51, and the light concentrator 57 and the focal point 59 of the multiple laser beams 58 formed by the light concentrator 57, relative to each other along the processing feed direction and the indexing feed direction. Here, in Embodiment 1, the processing feed direction is the X-axis direction of the laser processing apparatus 50, and the indexing feed direction is the Y-axis direction of the laser processing apparatus 50. The control unit of the laser processing apparatus 50 controls the operation of each component of the laser processing apparatus 50 to cause the laser processing apparatus 50 to perform the peel layer formation step 1001. The control unit of the laser processing apparatus 50 includes a computer system similar to the control unit of the inspection apparatus 1 described later.

[0028] In the peel layer formation step 1001, first, the control unit of the laser processing apparatus 50 transports the workpiece 100 onto the holding table 51 using a transport unit (not shown), and the holding table 51 holds the workpiece 100. Next, in the peel layer formation step 1001, the control unit of the laser processing apparatus 50 rotates the holding table 51 around the Z axis, etc., so that the upper surface 101 of the workpiece 100 held by the holding table 51 is parallel to the crystal orientation <100> The control unit of the laser processing apparatus 50 aligns a specific crystal orientation

[0010] of the workpiece 100 with the processing feed direction. However, the present invention is not limited to this, and may also align a specific crystal orientation

[0001] of the workpiece 100 with the processing feed direction.

[0029] In Embodiment 1, the delamination layer formation step 1001 includes a laser beam irradiation step 1011 and an indexing feed step 1012, as shown in Figure 3. The delamination layer formation step 1001 involves holding the workpiece 100 with a holding table 51, aligning a specific crystal orientation of the workpiece 100 with the processing feed direction, and then alternately performing the laser beam irradiation step 1011 and the indexing feed step 1012 to form a delamination layer 110 containing multiple modified layers and cracks inside the workpiece 100.

[0030] In the laser beam irradiation step 1011, the control unit of the laser processing apparatus 50 moves the focusing point 59 of the laser beam 58 and the workpiece 100 by the moving unit in the processing feed direction, that is, parallel to the upper surface 101 of the workpiece 100 and in the crystal orientation. <100> This step involves irradiating the workpiece 100 with a laser beam 58 using a focuser 57 while moving along a direction parallel to a specific crystal orientation (in Embodiment 1, crystal orientation

[0010] ) contained within the workpiece, thereby forming a modified layer parallel to the upper surface 101 and cracks extending from the modified layer inside the workpiece 100. When the workpiece 100 is irradiated with the laser beam 58 in the laser beam irradiation step 1011, a modified layer parallel to the upper surface 101 is formed near the focus point 59 of the laser beam 58 along a line parallel to the processing feed direction in which the laser beam 58 was irradiated, and cracks extending from both sides of the modified layer along a direction parallel to the upper surface 101 are formed. The modified layer is, for example, a region whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding area.

[0031] The indexing feed step 1012 is a step in which the control unit of the laser processing apparatus 50 uses a moving unit to index and feed the workpiece 100 relative to the focal point 59 of the laser beam 58 in the indexing feed direction, that is, in a direction perpendicular to the direction in which the modified layer was formed in the laser beam irradiation step 1011.

[0032] By alternately performing the laser beam irradiation step 1011 and the indexing feed step 1012 on the workpiece 100, a modified layer parallel to the upper surface 101 is formed near the focal point 59 of the laser beam 58 along multiple lines parallel to the processing feed direction, and cracks extending from the modified layers formed along adjacent lines connect with each other. As a result, by applying a predetermined external force, the workpiece 100 becomes capable of peeling off a wafer with a thickness corresponding to a depth 120, including the upper surface 101, starting from the peeling layer 110 containing these modified layers and cracks.

[0033] Figure 6 is a cross-sectional view illustrating an example of the configuration of inspection apparatus 1 according to Embodiment 1 and an example of the irradiation step 1002 and light receiving step 1003 in Figure 3. Figure 7 is a cross-sectional view illustrating another example of the configuration of inspection apparatus 1-2 according to Embodiment 1 and another example of the irradiation step 1002 and light receiving step 1003 in Figure 3. Figure 8 is a diagram illustrating the determination step 1004 in Figure 3. Figure 9 is a plan view showing an example of the determination step 1004 in Figure 3. In Embodiment 1, the irradiation step 1002, light receiving step 1003 and determination step 1004 are performed by inspection apparatus 1 according to Embodiment 1 shown in Figure 6 and inspection apparatus 1-2 according to Embodiment 1 shown in Figure 7.

[0034] The inspection apparatus 1 according to Embodiment 1 is an apparatus for inspecting a delamination layer 110 of a workpiece 100 made of single-crystal silicon manufactured such that specific crystal planes included in the crystal plane {100} are exposed on the upper surface 101 and the lower surface 102, respectively, by irradiating the workpiece 100 with a laser beam 58 of a transparent wavelength from the upper surface 101 side, thereby forming a delamination layer 110 consisting of a modified layer and cracks extending from the modified layer inside the workpiece 100. The apparatus is an apparatus for performing the irradiation step 1002, the light receiving step 1003 and the determination step 1004 of the workpiece inspection method according to Embodiment 1. As shown in Figure 6, the inspection apparatus 1 according to Embodiment 1 comprises a holding table 10, a light source 20, a light receiving unit 30, a determination means 40, a cover (not shown), and a display unit (not shown).

[0035] The holding table 10 holds the workpiece 100 with its upper surface 101 exposed. In Embodiment 1, the holding table 10 is a so-called chuck table comprising a disc-shaped frame with a recess formed therein and a disc-shaped suction part fitted into the recess. The suction part of the holding table 10 is formed from porous ceramic or the like, which has a large number of porous holes, and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). As shown in Figure 6, the upper surface of the suction part of the holding table 10 is a holding surface 11 on which the workpiece 100 is placed and which is held in place by suction from the vacuum suction source due to negative pressure introduced. In Embodiment 1, the workpiece 100 is placed with its upper surface 101 facing upward, and the holding surface 11 is held in place by suction from the lower surface 102. The holding surface 11 and the upper surface of the frame of the holding table 10 are located on the same plane and are formed parallel to the horizontal XY plane.

[0036] The holding table 10 is rotatable about an axis parallel to the Z-axis direction, which is vertical and perpendicular to the holding surface 11, by a rotational drive source (not shown). In Embodiment 1, the holding table 10 rotates by the rotational drive source, so that the processing feed direction, which is the direction in which the laser beam 58 is irradiated onto the workpiece 100 held on the holding table 10, can be aligned with the X-axis direction of the inspection device 1. The processing feed direction, which is the direction in which the laser beam 58 is irradiated onto the workpiece 100, is the direction in which the focal point 59 of the laser beam 58 is moved relative to the workpiece 100 in the laser beam irradiation step 1011, that is, parallel to the upper surface 101 of the workpiece 100 and relative to the crystal orientation. <100> This is a direction parallel to a specific crystal orientation included in (in Embodiment 1, the crystal orientation

[0010] ).

[0037] The light source 20 irradiates the entire upper surface 101 of the workpiece 100 held on the holding table 10 with light 25 of a wavelength that penetrates the workpiece 100 and is reflected by cracks. The light source 20 can be, for example, a halogen light that emits infrared rays or a light-emitting diode that emits infrared rays with a wavelength of 1450 nm. In Embodiment 1, the light source 20 is positioned to irradiate the entire upper surface 101 of the workpiece 100 with light 25 from a direction parallel to the X-axis direction of the inspection device 1. That is, the light source 20 is positioned so that, by aligning the processing feed direction, which is the direction in which the laser beam 58 is irradiated onto the workpiece 100 held on the holding table 10 as described above, with the X-axis direction of the inspection device 1, it is possible to irradiate the upper surface 101 of the workpiece 100 with light 25 from a direction parallel to a plane perpendicular to the upper surface 101 of the workpiece 100, including the processing feed direction, at a predetermined angle of incidence. Here, the predetermined angle of incidence is, for example, 20 degrees or more and 70 degrees or less in Embodiment 1.

[0038] The light receiving unit 30 is illuminated by the light source 20 over the entire upper surface 101 of the workpiece 100 and receives reflected light 35 reflected by cracks contained in the peeling layer 110. In Embodiment 1, the light receiving unit 30 is positioned opposite the central region of the upper surface 101 of the workpiece 100 held on the holding table 10, and has a light receiving field that covers the entire upper surface 101 of the workpiece 100 held on the holding table 10, and can obtain the intensity distribution of reflected light 35 from cracks contained in the entire peeling layer 110 of the workpiece 100 held on the holding table 10 in a single light receiving process. Here, the intensity distribution of reflected light 35 from cracks contained in the entire peeling layer 110 of the workpiece 100 held on the holding table 10 is data that associates the position where the reflected light 35 was received with the intensity of the reflected light 35. Furthermore, the intensity distribution of reflected light 35 from cracks contained in the entire surface of the peeling layer 110 of the workpiece 100 held on the holding table 10 is represented by each position where the position of receiving the reflected light 35 is projected onto the upper surface 101 of the workpiece 100 held on the holding table 10, and includes the entire upper surface 101 of the workpiece 100 held on the holding table 10. In the following, the intensity distribution of reflected light 35 from cracks contained in the entire surface of the peeling layer 110 of the workpiece 100 held on the holding table 10 will be appropriately referred to as the overall intensity distribution of reflected light 35.

[0039] The light-receiving unit 30 includes, for example, an image sensor that captures the entire surface of the upper surface 101 of the workpiece 100 held on the holding table 10. The image sensor is, for example, a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor. The light-receiving unit 30 can acquire an image 200 (see Figure 9) of the intensity distribution of the reflected light 35 across the entire surface. In Embodiment 1, the image 200 is represented by brightness corresponding to the intensity of the reflected light 35; that is, positions with high intensity of reflected light 35 are represented by high brightness, and positions with low intensity of reflected light 35 are represented by low brightness.

[0040] The determination means 40 determines the state of the peeling layer 110 based on the intensity of the reflected light 35 received by the light receiving unit 30. The determination means 40 is electrically connected to the light receiving unit 30 in a manner that enables information communication, and obtains the intensity distribution of the reflected light 35 across the entire surface from the light receiving unit 30. Based on this intensity distribution, it determines the state of the peeling layer 110 for each position projected onto the upper surface 101 of the workpiece 100 held on the holding table 10.

[0041] As shown in Figure 8, the intensity of the reflected light 35 received by the light receiving unit 30 changes depending on the state of the peeling layer 110 of the workpiece 100. Figure 8A shows the case where the workpiece 100 has not been processed. In this case, there is nothing inside the workpiece 100 that reflects the light 25 from the light source 20, so the intensity of the reflected light 35 received by the light receiving unit 30 is very weak. Figure 8B shows the case where the workpiece 100 has been irradiated with the laser beam 58 and a peeling layer 110 containing a modified layer and cracks has been formed, but adjacent cracks in the modified layer are not connected. In this case, although the cracks inside the workpiece 100 reflect the light 25, the parts where the cracks are not connected do not reflect the light 25, so the intensity of the reflected light 35 received by the light receiving unit 30 is relatively weak.

[0042] Figure 8C shows the case where the workpiece 100 is irradiated with a laser beam 58, forming a modified layer and a peeled layer 110 containing cracks, and adjacent cracks in the modified layer are connected but not peeled off. In this case, the cracks inside the workpiece 100 and the parts where the cracks are connected reflect the light 25, so the intensity of the reflected light 35 received by the light receiving unit 30 is relatively strong. Figure 8D shows the case where the workpiece 100 is irradiated with a laser beam 58, forming a modified layer and a peeled layer 110 containing cracks, and adjacent cracks in the modified layer are connected and peeled off. In this case, the peeled parts inside the workpiece 100 strongly reflect the light 25, so the intensity of the reflected light 35 received by the light receiving unit 30 is very strong.

[0043] In particular, the intensity of the reflected light 35 differs significantly between the case where cracks are connected but not separated in the delamination layer 110 and the case where delamination occurs in the delamination layer 110, with the latter case exhibiting a greater intensity of reflected light 35. When cracks are connected but not separated, there is almost no gap between the side of the workpiece 100 including the lower surface 102 (ingot side) and the side including the upper surface 101 (wafer side), for example, about 1 μm or less. Since this gap is smaller than the wavelength of the light 25 from the light source 20, light 25 is transmitted through the cracks. On the other hand, when delamination occurs, a gap of about 5 μm to 20 μm is created between the side of the workpiece 100 including the lower surface 102 (ingot side) and the side including the upper surface 101 (wafer side). This gap is filled with air or water, so the light 25 from the light source 20 is completely reflected without passing through this gap, becoming reflected light 35.

[0044] Thus, the intensity of the reflected light 35 received by the light receiving unit 30 changes according to the state of the peeling layer 110 of the workpiece 100. The determination means 40 can use this to determine the state of the peeling layer 110 based on the intensity of the reflected light 35 received by the light receiving unit 30. The determination means 40 has pre-registered the intensity of the reflected light 35 at the boundary between B and C in Figure 8 as a first predetermined value 41, the intensity of the reflected light 35 at the boundary between C and D in Figure 8 as a second predetermined value 42, and the intensity of the reflected light 35 at the boundary between A and B in Figure 8 as a third predetermined value 43. The first predetermined value 41 is smaller than the second predetermined value 42 and larger than the third predetermined value 43. The second predetermined value 42 is larger than the first predetermined value 41 and larger than the third predetermined value 43. The third predetermined value 43 is smaller than the first predetermined value 41 and smaller than the second predetermined value 42. The first predetermined value 41, the second predetermined value 42, and the third predetermined value 43 change depending on the irradiation intensity and irradiation conditions of the light 25 from the light source 20, and also change depending on the light receiving conditions of the reflected light 35 from the light receiving unit 30. Therefore, these values ​​are examined using pre-prepared samples of unprocessed workpieces 100, samples of workpieces 100 with a peeling layer 110 formed but with cracks that are not connected, samples of workpieces 100 with cracks that are connected but not peeled, and samples of peeled workpieces 100, and are registered in the determination means 40 in advance.

[0045] The determination means 40 uses the pre-registered first predetermined value 41, second predetermined value 42, and third predetermined value 43 to determine the state of the delamination layer 110 of the workpiece 100 based on the intensity of the reflected light 35 received by the light receiving unit 30. The determination means 40 determines whether adjacent cracks in the delamination layer 110 are connected based on whether the intensity of the reflected light 35 is greater than the first predetermined value 41. That is, the first predetermined value 41 is the criterion for determining whether adjacent cracks in the delamination layer 110 are connected. The determination means 40 also determines whether the wafer has delaminated from the workpiece 100 starting from the delamination layer 110 based on whether the intensity of the reflected light 35 is greater than the second predetermined value 42. That is, the second predetermined value 42 is the criterion for determining whether the wafer has delaminated from the workpiece 100 starting from the delamination layer 110. The determination means 40 determines whether or not a process to form the release layer 110 (for example, laser processing in the release layer formation step 1001) has been performed, based on whether or not the intensity of the reflected light 35 is greater than a third predetermined value 43. In other words, the third predetermined value 43 is the criterion for determining whether or not a process to form the release layer 110 has been performed.

[0046] A cover (not shown) is positioned to cover the holding table 10, the light source 20, and the light receiving unit 30, and is made of a material that blocks light from the outside. By blocking light from the outside, the cover (not shown) can improve the accuracy of the intensity of the reflected light 35 received by the light receiving unit 30, thereby improving the accuracy of the determination means 40's determination of the state of the peeled layer 110 of the workpiece 100.

[0047] The display unit (not shown) is mounted on the cover (not shown) of the inspection device 1 with its display surface facing outwards. It displays, for the operator's viewing convenience, an image 200 of the overall intensity distribution of reflected light 35 acquired by the light receiving unit 30 of the inspection device 1, and an image representing the judgment result from the judgment means 40 based on this intensity distribution. The display unit is composed of a liquid crystal display or the like. The display unit is equipped with an input unit used by the operator to input command information regarding various operations of the inspection device 1, the irradiation conditions of light 25, the light receiving conditions of reflected light 35, the display of images, etc. The input unit provided on the display unit is composed of at least one of a touch panel provided on the display unit and a keyboard or the like. The display unit is not fixed to the inspection device 1, but can be provided on any communication device, and any communication device may be connected to the inspection device 1 wirelessly or by wire.

[0048] The inspection device 1 according to Embodiment 1 includes a control unit (not shown). The control unit of the inspection device 1 controls the operation of each component of the inspection device 1 to cause the inspection device 1 to perform the irradiation step 1002, the light receiving step 1003, and the determination step 1004. In Embodiment 1, the control unit of the inspection device 1 includes a computer system. The computer system included in the control unit of the inspection device 1 includes an arithmetic processing unit having a microprocessor such as a CPU (Central Processing Unit), a storage device having memory such as ROM (Read Only Memory) or RAM (Random Access Memory), and an input / output interface device. The arithmetic processing unit of the control unit of the inspection device 1 performs arithmetic processing according to a computer program stored in the storage device of the control unit of the inspection device 1, and outputs control signals for controlling the inspection device 1 to each component of the inspection device 1 via the input / output interface device of the control unit of the inspection device 1. In Embodiment 1, the function of the determination means 40 is realized by the arithmetic processing unit of the control unit of the inspection device 1 executing a computer program stored in the storage device.

[0049] As shown in Figure 7, the inspection apparatus 1-2 according to Embodiment 1 is the same as the inspection apparatus 1 according to Embodiment 1, but with the number of light sources 20 increased to at least two (two in the example shown in Figure 7), and the other configurations are the same. Since the inspection apparatus 1-2 according to Embodiment 1 has multiple light sources 20, the amount of light 25 can be increased, and the uniformity of the light 25 irradiated onto the entire upper surface 101 of the workpiece 100 is improved. As a result, the amount of reflected light 35 received by the light receiving unit 30 can be increased, and the uniformity of the reflected light 35 from cracks contained in the entire peeling layer 110 of the workpiece 100 can be improved. This makes it possible to improve the accuracy of the determination means 40's determination of the state of the peeling layer 110 of the workpiece 100.

[0050] As shown in Figures 6 and 7, irradiation step 1002 is a step in which light 25 of a wavelength that penetrates the workpiece 100 and is reflected by cracks in the peeling layer 110 is irradiated onto the entire upper surface 101 of the workpiece 100 on which the peeling layer 110 is formed. In irradiation step 1002, first, the control unit of the inspection device 1,1-2 transports the workpiece 100 onto the holding table 10 using a transport unit (not shown), etc., and holds the workpiece 100 with the holding table 10. Next, in irradiation step 1002, the control unit of the inspection device 1,1-2 rotates the holding table 10 around the Z axis using a rotation drive source, etc., so that the processing feed direction, which is the direction in which the laser beam 58 is irradiated onto the workpiece 100 held on the holding table 10, is aligned with the X axis direction of the inspection device 1.

[0051] In irradiation step 1002, and in Embodiment 1, the control unit of the inspection device 1,1-2 irradiates the entire upper surface 101 of the workpiece 100 with light 25 from a direction parallel to the X-axis direction of the inspection device 1, as shown in Figures 6 and 7, using the light source 20. In this way, irradiation step 1002 irradiates the upper surface 101 of the workpiece 100 with light 25 from a direction parallel to a plane perpendicular to the upper surface 101 of the workpiece 100, including the processing feed direction, at a predetermined angle of incidence. This suppresses the flickering of reflected light 35, which is light reflected by cracks, and makes the reflected light 35 received by the light receiving unit 30 in the subsequent light receiving step 1003 clearer.

[0052] The light receiving step 1003 is a step in which the reflected light 35, which was irradiated in the irradiation step 1002 and reflected by the cracks, is received by the light receiving unit 30, as shown in Figures 6 and 7. The light receiving unit 30 irradiates the entire upper surface 101 of the workpiece 100 held on the holding table 10 by the light source 20 and receives the reflected light 35 reflected by the cracks contained in the peeling layer 110, and obtains the intensity distribution of the reflected light 35 across the entire surface.

[0053] The determination step 1004 is a step in which the state of the delamination layer 110 is determined based on the intensity of the reflected light 35 received in the light receiving step 1003. In the determination step 1004, the determination means 40 determines whether adjacent cracks in the delamination layer 110 are connected by checking whether the intensity of the reflected light 35 received in the light receiving step 1003 is greater than a first predetermined value 41. In the determination step 1004, the determination means 40 also determines whether the wafer has been delaminated from the workpiece 100 starting from the delamination layer 110 by checking whether the intensity of the reflected light 35 received in the light receiving step 1003 is greater than a second predetermined value 42. In the determination step 1004, the determination means 40 also determines whether the process of forming the delamination layer 110 has been performed by checking whether the intensity of the reflected light 35 is greater than a third predetermined value 43.

[0054] In the determination step 1004, for example, if the determination means 40 has obtained an image 200 shown in Figure 9 as the intensity distribution of the entire surface of the reflected light 35 in the light receiving step 1003, it determines that the region 201 in which the intensity of the reflected light 35 is greater than a first predetermined value 41 and less than a second predetermined value 42 is a region in which adjacent cracks in the delamination layer 110 are connected, and the region 202 in which the intensity of the reflected light 35 is greater than the second predetermined value 42 is a region in which the wafer is delaminating from the workpiece 100 starting from the delamination layer 110. It determines that the state of the delamination layer 110 on the entire surface of the delamination layer 110 of the workpiece 100 is either a state in which cracks are connected or the wafer is delaminating, that is, the state of the delamination layer 110 on the entire surface of the delamination layer 110 of the workpiece 100 is at least a state in which cracks are connected.

[0055] In the workpiece inspection method according to Embodiment 1, if the determination means 40 determines in the determination step 1004 that the state of the delamination layer 110 of the workpiece 100 is such that at least the cracks are connected across the entire surface of the delamination layer 110 (YES in step 1005 of Figure 3), the process proceeds to the delamination step 1006, in which an external force is applied to the workpiece 100 to further perform the delamination step 1006, in which the wafer is peeled off from the workpiece 100 starting from the delamination layer 110. On the other hand, in the workpiece inspection method according to Embodiment 1, if the determination means 40 determines in the determination step 1004 that the state of the delamination layer 110 of the workpiece 100 is such that at least the cracks are not connected across at least a part of the delamination layer 110 (NO in step 1005 of Figure 3), the process is terminated and the operator is prompted to review the process, for example, from the delamination layer formation step 1001.

[0056] The peeling step 1006 is a step in which an external force is applied to the workpiece 100 to peel the wafer from the workpiece 100, starting from the peeling layer 110. In Embodiment 1, the external force is, for example, ultrasonic vibration applied by the peeling device 60 described later, but the present invention is not limited to this, and any force that can peel the wafer from the workpiece 100, starting from the peeling layer 110, is acceptable.

[0057] Figures 10 and 11 are perspective views illustrating the peeling step 1006 of Figure 3. In Embodiment 1, the peeling step 1006 is performed by the peeling device 60 shown in Figures 10 and 11. As shown in Figures 10 and 11, the peeling device 60 comprises a holding table 61 that holds the workpiece 100 on a holding surface 62, an arm 63, a motor 64, a disc-shaped suction piece 65, a liquid supply unit (not shown), an ultrasonic vibration application means (not shown), a moving unit (not shown), and a control unit (not shown).

[0058] The holding table 61 is a chuck table that, for example, holds the workpiece 100 with its upper surface 101 exposed on the holding surface 62 and holds it by suction from the lower surface 102. The arm 63 is formed to extend horizontally. The motor 64 is formed in a disc shape and is provided at the tip of the arm 63. The disc-shaped suction piece 65 is provided on the lower surface of the motor 64 so as to be rotatable around its axis and suctions the workpiece 100 with its lower surface. The liquid supply unit supplies liquid between the upper surface 101 of the workpiece 100 and the ultrasonic vibration applying means which is arranged to face the upper surface 101 of the workpiece 100. The ultrasonic vibration applying means applies ultrasonic vibration to the workpiece 100 from the upper surface 101 side via the liquid supplied by the liquid supply unit from below. The moving unit moves the holding table 61 and the workpiece 100 held on the holding table 61, the arm 63, the motor 64, and the suction piece 65 relatively along the X-axis, Y-axis, and Z-axis directions. The moving unit also moves the holding table 61 and the workpiece 100 held on the holding table 61, the liquid supply unit, and the ultrasonic vibration application means relatively along the X-axis, Y-axis, and Z-axis directions. The control unit of the peeling device 60 controls the operation of each component of the peeling device 60 to cause the peeling device 60 to perform the peeling step 1006. The control unit of the peeling device 60 includes a computer system similar to that of the control unit of the inspection device 1. Note that the ultrasonic vibration application means is not limited to this form and may be built into the suction piece 65, and ultrasonic vibration may be applied from the lower surface of the suction piece 65.

[0059] In the peeling step 1006, first, the control unit of the peeling apparatus 60 transports the workpiece 100, which has undergone the peeling layer formation step 1001, onto the holding table 61 using a transport unit (not shown), and holds the workpiece 100 with the holding table 61 as shown in Figure 10.

[0060] In the peeling step 1006, the control unit of the peeling apparatus 60 moves the ultrasonic vibration applying means to a position where its lower surface faces the upper surface 101 of the workpiece 100 held on the holding table 61, using the moving unit, and also moves the liquid supply unit to a position where the liquid supply port of the liquid supply unit faces the space between the upper surface 101 of the workpiece 100 and the lower surface of the ultrasonic vibration applying means. In the peeling step 1006, the control unit of the peeling apparatus 60 then supplies liquid between the upper surface 101 of the workpiece 100 and the lower surface of the ultrasonic vibration applying means using the liquid supply unit, and applies ultrasonic vibration to the workpiece 100 from the upper surface 101 side via the liquid supplied by the liquid supply unit. In the peeling step 1006, after the application of ultrasonic vibration, the moving unit retracts the liquid supply unit and the ultrasonic vibration applying means from the workpiece 100 held on the holding table 61.

[0061] In the peeling step 1006, the control unit of the peeling device 60 moves the suction piece 65 by the moving unit to a position where the lower surface of the suction piece 65 contacts the upper surface 101 of the workpiece 100 held on the holding table 61, as shown in Figure 11. In the peeling step 1006, the control unit of the peeling device 60 uses the suction piece 65 to adsorb the upper surface 101 of the workpiece 100 with the lower surface of the suction piece 65, and rotates the suction piece 65 with the motor 64. In the peeling step 1006, the previously applied ultrasonic vibration and the external force generated by this rotation allow the wafer to be peeled from the workpiece 100, starting from the peeling layer 110 and including the upper surface 101, with a thickness corresponding to a depth of 120.

[0062] In addition, the present invention is not limited to the peeling step 1006. If an ultrasonic vibration application means is built into the suction piece 65, the control unit of the peeling device 60 may, using a moving unit, move the suction piece 65 to a position where the lower surface of the suction piece 65 contacts the upper surface 101 of the workpiece 100 held on the holding table 61, as shown in Figure 11. Then, the suction piece 65 will adsorb the upper surface 101 of the workpiece 100 with its lower surface, apply ultrasonic vibration from the lower surface of the suction piece 65 toward the upper surface 101 of the workpiece 100 using the ultrasonic vibration application means, and rotate the suction piece 65 with the motor 64 to peel off a wafer with a thickness corresponding to a depth 120 including the upper surface 101, starting from the peeling layer 110.

[0063] Furthermore, the peeling step 1006 is not limited to the use of the peeling apparatus 60 described above in the present invention. For example, the workpiece 100 after the peeling layer formation step 1001 may be placed in a water tank filled with water with its upper surface 101 exposed, and ultrasonic waves may be emitted from an ultrasonic emitting member positioned above the upper surface 101 of the workpiece 100. These ultrasonic waves stimulate the peeling layer 110 through the water in the tank, thereby peeling off a wafer from the workpiece 100 with a thickness corresponding to a depth 120 including the upper surface 101, starting from the peeling layer 110.

[0064] In the inspection method for the workpiece according to Embodiment 1, the peeling step 1006 is performed based on the determination result of the determination step 1004. However, the present invention is not limited to this, and the process may be terminated without performing the peeling step 1006, regardless of the determination result of the determination step 1004.

[0065] The workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1, having the configuration described above, irradiates the entire upper surface 101 of the workpiece 100 (Si ingot) with light 25 of a wavelength that penetrates the workpiece 100 and is reflected by the delamination layer 110 (crack), and determines the state of the delamination layer 110 inside the workpiece 100 by observing the intensity of the reflected light 35 reflected by the delamination layer 110. For this reason, the workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1 can determine the state of the delamination layer 110 over the entire upper surface 101 of the workpiece 100 by irradiating the entire upper surface 101 of the workpiece 100 with light 25 only once, so that the state of the delamination layer 110 can be determined in a short time without reducing productivity, regardless of the size of the workpiece 100. Furthermore, the workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1 have the effect of being able to determine the state of the delamination layer 110 without being affected by saw marks, by determining the formation status of the delamination layer 110, more specifically whether adjacent cracks are connected or whether connected cracks have spread and separated the ingot side and wafer side of the workpiece 100, based on the intensity of the reflected light 35.

[0066] Furthermore, the workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1 determine whether adjacent cracks in the peeling layer 110 are connected based on whether the intensity of the reflected light 35 is greater than a first predetermined value 41. Therefore, it is possible to determine whether adjacent cracks are connected quickly, efficiently, and accurately without being affected by saw marks.

[0067] Furthermore, the workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1 determine whether the wafer has separated from the workpiece 100 starting from the delamination layer 110 by checking whether the intensity of the reflected light 35 is greater than a second predetermined value 42 which is greater than a first predetermined value 41. Therefore, it is possible to determine whether the ingot side and wafer side of the workpiece 100 have separated in a short time, efficiently and accurately, without being affected by saw marks.

[0068] Furthermore, the workpiece inspection method and inspection apparatus 1,1-2 according to Embodiment 1 irradiates the upper surface 101 of the workpiece 100 with light 25 from a direction parallel to a plane perpendicular to the upper surface 101 of the workpiece 100, including the processing feed direction which is the direction in which the laser beam 58 was irradiated, at a predetermined incident angle. This suppresses the flickering of reflected light 35, which is light reflected by cracks, and makes the reflected light 35 received by the light receiving unit 30 in the subsequent light receiving step 1003 clearer, thereby enabling a clearer determination based on the intensity of the reflected light 35.

[0069] Furthermore, in the workpiece inspection method according to Embodiment 1, if it is determined in the determination step 1004 that adjacent cracks in the delamination layer 110 are connected, the delamination step 1006 is performed further, thus enabling efficient wafer delamination.

[0070] Furthermore, in the workpiece inspection method according to Embodiment 1, the peel layer formation step 1001 is performed by alternately performing the laser beam irradiation step 1011 and the indexing feed step 1012, thereby forming a peel layer 110 containing multiple modified layers and cracks inside the workpiece 100. This allows for the formation of modified layers parallel to the upper surface 101 near the focal point 59 of the laser beam 58 along multiple lines parallel to the processing feed direction, and allows for the extension of cracks from the modified layers formed along adjacent lines, connecting the cracks to each other. Therefore, by applying a predetermined external force, it is possible to peel off a wafer with a thickness corresponding to a depth 120 including the upper surface 101 from the workpiece 100, starting from the peel layer 110 containing these modified layers and cracks.

[0071] Furthermore, since the inspection apparatus 1-2 according to Embodiment 1 has at least two light sources 20, the amount of light 25 can be increased, and the uniformity of the light 25 irradiated onto the entire upper surface 101 of the workpiece 100 is improved. As a result, the amount of reflected light 35 received by the light receiving unit 30 can be increased, and the uniformity of the reflected light 35 from cracks contained in the entire peeling layer 110 of the workpiece 100 can be improved. This makes it possible to improve the accuracy of the determination means 40's determination of the state of the peeling layer 110 of the workpiece 100.

[0072] [Embodiment 2] A method for inspecting a workpiece according to Embodiment 2 of the present invention will be described with reference to the drawings. Figure 12 is a flowchart showing the processing procedure of the workpiece inspection method according to Embodiment 2. In Figure 12, the same reference numerals are used for parts that are the same as in the embodiment and their descriptions are omitted.

[0073] The workpiece inspection method according to Embodiment 2, as shown in Figure 12, is modified in that, in Embodiment 1, instead of performing the peeling step 1006 when it is determined in the determination step 1004 that adjacent cracks in the peeling layer 110 are connected, the peeling step 1006 is performed after the peeling layer formation step 1001 is performed, and if the wafer cannot be peeled from the workpiece 100 in the peeling step 1006 (NO in step 1007 in Figure 12), the irradiation step 1002, the light receiving step 1003 and the determination step 1004 are performed. The other configurations are the same as in Embodiment 1.

[0074] Even after performing the peeling step 1006, the wafer may not be able to be peeled from the workpiece 100 due to reasons such as the presence of areas on the surface parallel to the upper surface 101 inside the workpiece 100 where the peeling layer 110 has not been formed. In the workpiece inspection method according to Embodiment 2, if the wafer could not be peeled from the workpiece 100 in the peeling step 1006 (NO in step 1007 in Figure 12), the irradiation step 1002, the light receiving step 1003, and the determination step 1004 are performed, and for example, in the determination step 1004, it is determined whether or not the wafer has been peeled from the workpiece 100 starting from the peeling layer 110. In the workpiece inspection method according to Embodiment 2, if the wafer can be peeled from the workpiece 100 in the peeling step 1006 (YES in step 1007 in Figure 12), the process is terminated.

[0075] The workpiece inspection method according to Embodiment 2 involves performing a delamination layer formation step 1001, followed by a delamination step 1006 in which an external force is applied to the workpiece 100 to delaminate the wafer from the workpiece 100 starting from the delamination layer 110. If the wafer cannot be delaminated from the workpiece 100 in the delamination step 1006, then the irradiation step 1002, the light receiving step 1003, and the determination step 1004 are performed. Thus, the workpiece inspection method according to Embodiment 1 performs the irradiation step 1002, the light receiving step 1003, and the determination step 1004 only when there is a possibility of a defect in the delamination layer 110, allowing for efficient determination of the state of the delamination layer 110.

[0076] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention. [Explanation of Symbols]

[0077] 1,1-2 Inspection device 10 Retention Table 20 light source 25 light 30 Light receiving unit 35 Reflected light 40 Judgment means 41 First predetermined value 42 Second predetermined value 58 Laser beams 59 Focusing point 100 Workpiece 101 Top surface 102 Bottom surface 110 Delamination layer 120 depth

Claims

1. A method for inspecting a workpiece made of single-crystal silicon manufactured such that a specific crystal plane included in the crystal plane {100} is exposed on the upper and lower surfaces, respectively, A delamination layer formation step involves positioning the focal point of a laser beam with a wavelength that is transparent to the workpiece at a depth corresponding to the thickness of the wafer being manufactured, from the top surface of the workpiece, and irradiating the workpiece with the laser beam while moving the focal point and the workpiece relative to each other in the processing feed direction, thereby forming a modified layer parallel to the top surface and cracks extending from the modified layer inside the workpiece. After performing the peel layer formation step, an irradiation step is performed in which light of a wavelength that penetrates the workpiece and is reflected by cracks in the peel layer is irradiated onto the entire upper surface of the workpiece on which the peel layer has been formed, A light receiving step in which the reflected light irradiated in the irradiation step and reflected by the crack is received, A determination step in which the state of the peeled layer is determined based on the intensity of the reflected light received in the light receiving step, A method for inspecting a workpiece, characterized by comprising the following features.

2. In this determination step, it is determined whether adjacent cracks in the delamination layer are connected or not based on whether the reflected light intensity is greater than a first predetermined value. The method for inspecting a workpiece according to claim 1, characterized in that, if it is determined in the determination step that adjacent cracks in the delamination layer are connected, an external force is applied to the workpiece to further perform a delamination step in which the wafer is peeled off from the workpiece starting from the delamination layer.

3. After performing the delamination layer formation step, a further delamination step is performed in which an external force is applied to the workpiece to delaminate the wafer from the workpiece, starting from the delamination layer. The method for inspecting a workpiece according to claim 1, characterized in that if the wafer could not be peeled off the workpiece in the peeling step, the irradiation step, the light receiving step, and the determination step are performed.

4. The method for inspecting a workpiece according to claim 3, characterized in that in the determination step, it is determined whether or not the wafer has peeled off from the workpiece starting from the peel layer, based on whether or not the reflected light intensity is greater than a second predetermined value which is greater than a first predetermined value which is a criterion for determining whether or not adjacent cracks in the peel layer are connected.

5. The peel layer formation step is, A laser beam irradiation step in which the laser beam is irradiated while the focal point of the laser beam and the workpiece are moved along a direction parallel to the upper surface of the workpiece and parallel to a specific crystal orientation included in the crystal orientation <100>, thereby forming a modified layer parallel to the upper surface and cracks extending from the modified layer inside the workpiece; An indexing feed step is performed in which the focal point of the laser beam and the workpiece are relatively indexed and fed in a direction perpendicular to the direction in which the modified layer was formed in the laser beam irradiation step, A method for inspecting a workpiece according to claim 2, 3, or 4, characterized in that by performing the steps alternately, a plurality of modified layers and a peeled layer containing cracks are formed inside the workpiece.

6. The method for inspecting a workpiece according to claim 5, characterized in that the light irradiated in the irradiation step is irradiated onto the upper surface of the workpiece at a predetermined angle of incidence from a direction parallel to a plane perpendicular to the upper surface of the workpiece, including the processing feed direction.

7. An inspection device for inspecting a delamination layer formed inside a workpiece made of single-crystal silicon manufactured such that specific crystal planes included in the crystal plane {100} are exposed on the upper and lower surfaces, respectively, by irradiating the workpiece with a laser beam of a penetrating wavelength from the upper surface side, thereby inspecting the delamination layer of the workpiece, which consists of a modified layer and cracks extending from the modified layer. A holding table that exposes the upper surface of the workpiece and holds the workpiece, A light source that irradiates the entire upper surface of a workpiece held on the holding table with light of a wavelength that passes through the workpiece and is reflected by the cracks, A light receiving unit that receives reflected light from the cracks contained in the peeling layer, which is irradiated onto the entire upper surface of the workpiece by the light source, A determination means for determining the state of the peeled layer based on the reflected light intensity received by the light receiving unit, An inspection device characterized by being equipped with the following features.

8. The inspection apparatus according to claim 7, characterized in that the determination means determines whether adjacent cracks in the delamination layer are connected based on whether the reflected light intensity is greater than a first predetermined value.

9. The inspection apparatus according to claim 7, characterized in that the determination means determines whether the wafer has peeled off from the workpiece starting from the peel layer, based on whether the reflected light intensity is greater than a second predetermined value which is greater than a first predetermined value which is a criterion for determining whether adjacent cracks in the peel layer are connected or not.

10. The workpiece is irradiated with a laser beam parallel to its upper surface and along a direction parallel to a specific crystal orientation included in the crystal orientation <100>, thereby forming a modified layer parallel to the upper surface and a delamination layer containing cracks extending from the modified layer. The inspection apparatus according to any one of claims 7 to 9, characterized in that the light source is positioned so as to be able to irradiate the upper surface of the workpiece with light at a predetermined angle of incidence from a direction parallel to a plane perpendicular to the upper surface of the workpiece, including the processing feed direction which is the direction in which the laser beam was irradiated.

11. The inspection apparatus according to claim 10, characterized in that the light source comprises at least two.

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