Wafer inspection device and wafer inspection method

Abstract

A dicing device 3 (wafer inspection device) comprises: an illumination unit 332 that emits illumination light toward a modified layer K of a wafer We in which the modified layer K was formed therein by radiation of a laser; an imaging unit 331 that, on the basis of the illumination light emitted from the illumination unit 332, images the modified layer K in the wafer from above in a diagonal direction; and a control unit 7 that acquires the shape of the modified layer K in the wafer, on the basis of the results of imaging the modified layer K in the wafer We by mean of the imaging unit 331.

Description

Wafer inspection device and wafer inspection method

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

[0002] 2. Description of the Related Art Conventionally, wafer inspection devices for inspecting wafers have been known. Such wafer inspection devices are disclosed, for example, in Japanese Patent Laid-Open Publication No. 2019-140167.

[0003] Japanese Patent Application Laid-Open No. 2019-140167 discloses a wafer inspection device equipped with an imaging unit that images a modified layer formed in a wafer by laser irradiation. This wafer inspection device is configured to use the imaging unit to image the modified layer in the wafer from above and inspect the state of the modified layer based on the captured image.

[0004] Japanese Patent Application Laid-Open No. 2019-140167

[0005] However, in the wafer inspection device of JP 2019-140167 A, the imaging unit images the modified layer in the wafer from above, and the state of the modified layer is inspected based on the captured image. Therefore, when multiple modified layers are formed by irradiating the wafer with a laser at different depth positions, it is difficult to obtain the vertical state of the modified layer by imaging from above, making it difficult to accurately inspect the state of the modified layer formed in the wafer. Therefore, it is desirable to accurately inspect the state of the modified layer formed in the wafer.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a wafer inspection device and a wafer inspection method that are capable of accurately inspecting the state of a modified layer formed within a wafer.

[0007] A wafer inspection device according to a first aspect of the present invention includes an illumination unit that irradiates illumination light toward a modified layer of a wafer in which a modified layer has been formed by irradiating it with a laser, an imaging unit that images the modified layer in the wafer from diagonally above based on the illumination light irradiated from the illumination unit, and a control unit that acquires the shape of the modified layer in the wafer based on the imaging results of the modified layer in the wafer by the imaging unit.

[0008] As described above, the wafer inspection device according to the first aspect of the present invention includes an imaging unit that images the modified layer in the wafer from diagonally above, and a control unit that acquires the shape of the modified layer in the wafer based on the imaging results of the modified layer in the wafer by the imaging unit. This allows the vertical shape of the modified layer in the wafer to be acquired by imaging from diagonally above by the imaging unit, thereby enabling the vertical state of the modified layer in the wafer to be acquired with high accuracy. As a result, the state of the modified layer formed in the wafer can be inspected with high accuracy.

[0009] In the wafer inspection device according to the first aspect, the control unit preferably controls the imaging unit to capture images of the same position on the wafer from a plurality of obliquely upward directions that are different from each other in a plan view, and acquires a three-dimensional shape of the modified layer in the wafer based on the images of the modified layer in the wafer captured from a plurality of obliquely upward directions. With this configuration, the three-dimensional shape of the modified layer in the wafer can be accurately acquired by performing a composite operation on the images of the modified layer in the wafer captured from a plurality of obliquely upward directions that are different from each other in a plan view, thereby enabling more accurate inspection of the state of the modified layer formed in the wafer.

[0010] In the wafer inspection device according to the first aspect, preferably, the semiconductor chips separated from the wafer along the modified layers have a rectangular shape in a plan view, and the imaging unit is configured to image each side of the rectangular semiconductor chip from an oblique direction in a plan view. This configuration allows multiple modified layers formed along two mutually perpendicular sides of the rectangular semiconductor chip in a plan view to be simultaneously imaged from above at an oblique angle, thereby preventing the number of times modified layers are imaged from increasing. As a result, inspection of the modified layers can be performed efficiently.

[0011] The wafer inspection device configured to image the same position on the wafer from multiple obliquely upward directions in different directions in a plan view preferably further includes a rotation drive unit that rotates the wafer about a rotation axis in the vertical direction, and the control unit controls the imaging unit to image the modified layer in the wafer at multiple rotation angles to which the wafer is rotated by the rotation drive unit. With this configuration, the modified layer in the wafer can be imaged from multiple angles using a common imaging unit, making it possible to more accurately inspect the state of the modified layer formed in the wafer without increasing the number of imaging units.

[0012] In the wafer inspection device configured to image the same position on the wafer from multiple diagonally upward directions that are different from each other in a plan view, preferably, the imaging unit is configured to be able to simultaneously image from multiple diagonally upward directions, and the control unit controls the imaging unit to image the modified layer in the wafer from multiple diagonally upward directions. With this configuration, the modified layer in the wafer can be simultaneously imaged from multiple angles, thereby preventing the image capturing time of the modified layer in the wafer from becoming long and enabling more accurate inspection of the state of the modified layer formed in the wafer.

[0013] In the wafer inspection device according to the first aspect, the imaging unit is preferably configured to image the wafer from obliquely above and from above, and the control unit acquires the shape of the modified layer in the wafer based on the images of the modified layer in the wafer from obliquely above and from above by the imaging unit. With this configuration, by imaging the modified layer in the wafer from above as well, the shape of the modified layer in the wafer in a planar view can be acquired with high accuracy, and the state of the modified layer formed in the wafer can be inspected with high accuracy.

[0014] In the wafer inspection apparatus according to the first aspect, the imaging unit preferably includes an optical system having an imaging plane that satisfies the Scheimpflug condition for the wafer surface. With this configuration, by imaging the wafer from obliquely above, the focal position of the imaging unit can be adjusted even if the distance between the imaging unit and the wafer surface varies depending on the position of the wafer, and therefore, it is possible to prevent the image of the modified layer in the wafer imaged from obliquely above from becoming blurred.

[0015] A wafer inspection method according to a second aspect of the present invention involves irradiating an illumination light onto a modified layer of a wafer in which a modified layer has been formed by irradiating it with a laser, imaging the modified layer in the wafer from diagonally above based on the illumination light using an imaging unit, and obtaining the shape of the modified layer in the wafer based on the imaging results of the modified layer in the wafer by the imaging unit.

[0016] In the wafer inspection method according to the second aspect of the present invention, as described above, the modified layer in the wafer is imaged from diagonally above by the imaging unit, and the shape of the modified layer in the wafer is obtained based on the image of the modified layer in the wafer obtained by the imaging unit. This allows the vertical shape of the modified layer in the wafer to be obtained by imaging from diagonally above by the imaging unit, so the vertical state of the modified layer in the wafer can be obtained with high accuracy. As a result, a wafer inspection method can be provided that can accurately inspect the state of the modified layer formed in the wafer.

[0017] In the wafer inspection method according to the second aspect, preferably, imaging the modified layer by the imaging unit includes imaging the same position on the wafer from a plurality of obliquely upward directions that are different from each other in a plan view, and acquiring the shape of the modified layer in the wafer includes acquiring a three-dimensional shape of the modified layer in the wafer based on the imaging results of the modified layer in the wafer imaged from a plurality of obliquely upward directions. With this configuration, the three-dimensional shape of the modified layer in the wafer can be accurately acquired by performing a composite operation on the images of the modified layer in the wafer imaged from a plurality of obliquely upward directions that are different from each other in a plan view, thereby making it possible to more accurately inspect the state of the modified layer formed in the wafer.

[0018] According to the present invention, as described above, the state of the modified layer formed in the wafer can be inspected with high precision.

[0019] 1 is a schematic diagram showing an overview of a semiconductor wafer processing system provided with a dicing apparatus and an expanding apparatus according to an embodiment; FIG. 2 is a plan view showing a tape application apparatus of a semiconductor wafer processing system according to an embodiment; FIG. 3 is a plan view showing a grinding apparatus of a semiconductor wafer processing system according to an embodiment; FIG. 4 is a plan view showing a tape replacement apparatus of a semiconductor wafer processing system according to an embodiment; FIG. 5 is a plan view showing a grooving apparatus of a semiconductor wafer processing system according to an embodiment; FIG. 6 is a plan view showing a dicing apparatus of a semiconductor wafer processing system according to an embodiment; FIG. 7 is a plan view showing an expanding apparatus of a semiconductor wafer processing system according to an embodiment; FIG. 8 is a flowchart showing a semiconductor chip manufacturing process of a semiconductor wafer processing system according to an embodiment; FIG. 9 is a side view showing an inspection unit of a dicing apparatus according to an embodiment; FIG. 10 is a side view for explaining imaging by an imaging unit of a dicing apparatus according to an embodiment; FIG. 11 is a plan view for explaining imaging by an imaging unit of a dicing apparatus according to an embodiment; FIG. 12 is a diagram for explaining inspection of a modified layer by an inspection unit of a dicing apparatus according to an embodiment; FIG. 13 is a perspective view showing a schematic example of a modified layer inspected by the inspection unit of a dicing apparatus according to an embodiment; FIG. 14 is a diagram for explaining acquisition of the shape of a modified layer by the inspection unit of a dicing apparatus according to an embodiment; FIG. 10 is a diagram showing an imaging unit of a semiconductor wafer processing system according to a modified example of the embodiment.

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0021] The configuration of a semiconductor wafer processing system 100 according to an embodiment of the present invention will be described with reference to FIGS.

[0022] (Semiconductor Wafer Processing System) As shown in FIG. 1, the semiconductor wafer processing system 100 is an apparatus for processing a wafer We. The semiconductor wafer processing system 100 is configured to form a modified layer (modified portion) on the wafer We and divide the wafer We along the modified layer to form multiple semiconductor chips Ch. Here, the wafer We is a thin, circular plate formed from crystals of a semiconductor material that is the material for semiconductor integrated circuits. A modified layer is formed inside the wafer We along a dividing line through processing in the semiconductor wafer processing system 100. In other words, the wafer We is processed so that it can be divided along the dividing line. Here, the modified layer refers to cracks, voids, etc. formed inside the wafer We by the laser Ld.

[0023] Specifically, the semiconductor wafer processing system 100 includes a tape application device 1, a grinding device 2, a tape replacement device 3, a grooving device 4, a dicing device 5, and an expanding device 6.

[0024] As shown in FIG. 1, in the semiconductor wafer processing system 100, a wafer We is processed in the following order: a tape applying device 1, a grinding device 2, a tape replacing device 3, a grooving device 4, a dicing device 5, and an expanding device 6.

[0025] <Taping Apparatus> The tape applying apparatus 1 is configured to apply a protective tape Tb to the circuit surface of a wafer We (see FIG. 1).

[0026] Specifically, as shown in FIG. 2 , the tape application device 1 includes a cassette storage unit 11, a robot hand 12, a transport mechanism 13, and a protective tape application unit 14. The cassette storage unit 11 is configured to store frames Rf, wafers We, and wafers We with frames Rf attached thereto. The robot hand 12 is configured to transport each of the frames Rf and wafers We from the cassette storage unit 11 to the transport mechanism 13. The robot hand 12 is configured to transport the wafers We with frames Rf attached thereto from the transport mechanism 13 to the cassette storage unit 11. The transport mechanism 13 is configured to transport the wafers We to a position in the protective tape application unit 14 where the protective tape Tb can be applied. The protective tape application unit 14 is configured to apply the protective tape Tb to the wafers We transported by the transport mechanism 13 and to apply the frames Rf to the protective tape Tb.

[0027] <Grinding Device> The grinding device 2 is configured to reduce the thickness of the wafer We by grinding the wafer We from the surface opposite to the circuit surface (see FIG. 1).

[0028] Specifically, as shown in FIG. 3, the grinding device 2 includes a first cassette unit 21, a robot hand 22, a plurality of suction holding units 23, a plurality of grinding units 24, a finish polishing unit 25, a crystal defect forming unit 26, a second cassette unit 27, and a single rotating table unit 28.

[0029] The first cassette unit 21 is configured to accommodate wafers We before grinding. The robot hand 22 is configured to transport the wafer We, to which the frame Rf is attached, from the first cassette unit 21 to one of the plurality of suction holders 23 that is closest to the first cassette unit 21. The robot hand 22 is also configured to transport the wafer We, to which the frame Rf is attached, after grinding, to the second cassette unit 27 from one of the plurality of suction holders 23 that is closest to the second cassette unit 27. The plurality of suction holders 23 are configured to suck and hold the wafer We, to which the frame Rf is attached, to the protective tape Tb.

[0030] The plurality of grinding units 24 are configured to grind the back surface of the wafer We, which is the side opposite the circuit surface, in stages. The plurality of grinding units 24 include a rough grinding unit 24a, a finish grinding unit 24b, and a fine grinding unit 24c. The rough grinding unit 24a is configured to grind the back surface of the wafer We with a first abrasive having a first particle diameter. The finish grinding unit 24b is configured to grind the back surface of the wafer We with a second abrasive having a second particle diameter smaller than the first particle diameter. The fine grinding unit 24c is configured to grind the back surface of the wafer We with a third abrasive having a third particle diameter smaller than the second particle diameter.

[0031] The finish polishing unit 25 is configured to polish the back surface of the wafer We ground by the multiple grinding units 24. The crystal defect forming unit 26 is configured to form minute crystal defects on the back surface of the wafer We ground by the finish polishing unit 25. The crystal defect forming unit 26 is configured to perform a so-called gettering operation. The second cassette unit 27 is configured to accommodate the wafer We on which crystal defects have been formed in the crystal defect forming unit 26. Each of the multiple suction holding units 23 is configured to rotate and move to positions corresponding to the single rotary table unit 28, the multiple grinding units 24, the finish polishing units 25, and the crystal defect forming unit 26, respectively.

[0032] <Tape Replacing Device> The tape replacing device 3 is configured to, after grinding the wafer We in the grinding device 2, apply an expanding tape Te to the surface of the wafer We opposite the circuit surface, and peel off the protective tape Tb applied to the circuit surface of the wafer We (see FIG. 1).

[0033] Specifically, as shown in FIG. 4, the tape replacement device 3 includes a cassette storage section 31, a robot hand 32, a conveying mechanism 33, an expanding tape application section 34, and a protective tape peeling section (not shown).

[0034] The cassette storage section 31 is configured to be able to store a wafer We attached to a protective tape Tb together with a frame Rf, and a wafer We attached to an expanding tape Te together with a frame Rf.

[0035] The robot hand 32 is configured to transport the wafer We, which is attached to the protective tape Tb together with the frame Rf, from the cassette storage unit 31 to the transport mechanism 33. The transport mechanism 33 is configured to transport the wafer We, which is attached to the protective tape Tb together with the frame Rf, to the expanding tape applying unit 34. The expanding tape applying unit 34 is configured to apply the expanding tape Te to the surface of the frame Rf opposite to the surface to which the protective tape Tb is attached, thereby applying the frame Rf and the wafer We to the protective tape Tb and the expanding tape Te, respectively.

[0036] <Grooving Device> The grooving device 4 is configured to irradiate a laser beam Lg along the streets Ws between the semiconductor chips Ch on the circuit surface of the wafer We, to which the frame Rf and protective tape Tb are not attached, to separate the insulating film and the test pattern before the dicing device 5 forms a modified layer on the wafer We. Here, the laser beam Lg is light with a wavelength shorter than that of the infrared region. The insulating film is the interlayer insulating film of the wafer We. The insulating film is formed of a low-k material with a relatively low dielectric constant as an interlayer insulating film material. The test pattern is a test conductive pattern for performing a function test on the semiconductor chips Ch on the wafer We. The test pattern is a so-called TEG (Test Element Group).

[0037] Specifically, as shown in FIG. 5 , the grooving device 4 includes a cassette unit 41, a laser irradiation unit 42, and a circuit surface coating and cleaning unit 43. The cassette unit 41 is configured to accommodate a wafer We to which a frame Rf and a protective tape Tb are not attached. The laser irradiation unit 42 is configured to irradiate a laser Lg that separates the insulating film and the test pattern on the wafer We. The circuit surface coating and cleaning unit 43 is configured to coat the circuit surface of the wafer We before separating the insulating film and the test pattern, and to clean the circuit surface of the wafer We after separating the insulating film and the test pattern.

[0038] <Dicing Apparatus> The dicing apparatus 5 is configured to form a modified layer inside the wafer We for dividing the wafer We (see FIG. 1). The dicing apparatus 5 is an example of a "wafer inspection apparatus" in the claims.

[0039] Specifically, as shown in FIG. 6 , the dicing apparatus 5 includes a dicing unit 50, a cassette unit 51, and a wafer transport unit 52. The dicing unit 50 is configured to form a modified layer by irradiating the wafer We with a laser beam Ld (see FIG. 1 ) having a wavelength that is transparent to the wafer We along the streets Ws (division lines). Here, the laser beam Ld is light having a wavelength in the near-infrared region. The dicing apparatus 5 is also configured to form a modified layer by irradiating the wafer We with the laser beam Ld while moving and rotating the wafer We. The cassette unit 51 is configured to accommodate multiple wafers We attached to protective tape Tb together with frames Rf. The wafer transport unit 52 is configured to transport the wafers We attached to protective tape Tb together with frames Rf between the cassette unit 51 and the dicing unit 50.

[0040] <Expanding Device> The expanding device 6 is configured to attach an expanding tape Te to the surface of the wafer We opposite the circuit surface, and then expand the expanding tape Te to divide the wafer We into a plurality of semiconductor chips Ch (see FIG. 1).

[0041] Specifically, as shown in Figure 7, the expansion device 6 includes a cassette section 601, a lift-up hand section 602, a suction hand section 603, a cooling unit 605, an expansion section 606, an expansion maintenance member 607, a heat shrink section, an ultraviolet irradiation section, a squeegee section 610, and a clamp section 611.

[0042] The cassette unit 601 is configured to be able to store a wafer ring structure W in which a frame Rf and a wafer We are attached to an expanding tape Te. The lift-up hand unit 602 is configured to be able to remove the wafer ring structure W from the cassette unit 601. The lift-up hand unit 602 is configured to be able to store the wafer ring structure W in the cassette unit 601. The suction hand unit 603 is configured to suck the frame Rf of the wafer ring structure W from above.

[0043] The cooling unit 605 is configured to cool the expanding tape Te from below. The expanding section 606 is configured to expand the expanding tape Te of the wafer ring structure W to divide the wafer We along the streets Ws (see FIG. 1 ). The expansion maintaining member 607 is configured to press the expanding tape Te from above to prevent the expanding tape Te near the wafer We from shrinking due to heating by the heat shrink section. The heat shrink section is configured to shrink the expanding tape Te expanded by the expanding section 606 by heating while maintaining the gaps between the multiple semiconductor chips Ch. The ultraviolet irradiation section is configured to irradiate the expanding tape Te with ultraviolet light to reduce the adhesive strength of the adhesive layer of the expanding tape Te.

[0044] The squeegee unit 610 is configured to further divide the wafer We along the modified layer by locally pressing the wafer We from below after expanding the expanding tape Te. The clamp unit 611 is configured to be able to move the wafer ring structure W in the vertical direction while gripping the frame Rf of the wafer ring structure W.

[0045] (Semiconductor Chip Manufacturing Process) The overall operation of the semiconductor wafer processing system 100 will now be described with reference to FIG.

[0046] In step S1, the wafer We and the frame Rf are applied to the protective tape Tb in the tape application device 1. That is, the protective tape application unit 14 applies the protective tape Tb to the wafer We transported by the transport mechanism 13, and also applies the frame Rf to the protective tape Tb.

[0047] In step S2, the modified layer is removed from the wafer We in the grinding device 2. That is, the plurality of grinding units 24 grinds the back surface of the wafer We, which is the side opposite to the circuit surface, in stages to thin the wafer We.

[0048] In step S3, the protective tape Tb is peeled off in the tape replacing device 3, and the wafer We and the frame Rf are attached to the expanding tape Te. That is, the expanding tape attaching unit 34 peels off the protective tape Tb from the wafer We with the frame Rf, and then attaches the expanding tape Te to the wafer We from which the protective tape Tb has been peeled off, and also attaches the frame Rf to the expanding tape Te.

[0049] In step S4, the insulating film and the test pattern are divided in the grooving device 4. That is, the laser irradiation unit 42 irradiates the laser Lg along the streets Ws between the semiconductor chips Ch on the circuit surface of the wafer We that is not attached to the protective tape Tb together with the frame Rf, thereby dividing the insulating film and the test pattern.

[0050] In step S5, a modified layer is formed on the wafer We in the dicing device 5. That is, the dicing unit 50 forms a modified layer by irradiating the wafer We with a laser Ld (see FIG. 1) along the streets Ws.

[0051] In step S6, the expanding tape Te is expanded in the expanding device 6, and the wafer We is divided into a plurality of semiconductor chips Ch. That is, the clamp unit 611 is lowered while holding the frame Rf, and the expanding tape Te that is in contact with the expanding unit 606 is pulled downward, thereby expanding the expanding tape Te. As a result, the expanding tape Te is divided along the cracks formed in the streets Ws of the wafer We due to the tensile force generated in the expanding tape Te by the expansion, and the wafer We is divided into a plurality of semiconductor chips Ch.

[0052] After step S6, the semiconductor chip manufacturing process ends.

[0053] (Inspection of modified layer formed in wafer) In the semiconductor wafer processing system 100, after a modified layer K is formed on the wafer We in the dicing device 5, the formed modified layer K can be imaged to inspect the state of the modified layer K.

[0054] Specifically, the inspection unit 53 of the dicing device 5 takes an image of the wafer We and inspects the state of the modified layer K of the wafer We.

[0055] The state of the modified layer K is inspected by the control unit 7 (see FIG. 9). The control unit 7 is configured by, for example, a computer. The control unit 7 includes a processing unit such as a CPU (Central Processing Unit) and a storage unit such as a memory, and performs control processing by executing a program using the processing unit.

[0056] 9 and 10 , in this embodiment, the inspection unit 53 includes an illumination unit 532 that irradiates illumination light toward the modified layer K of the wafer We, inside which a modified layer K has been formed by irradiating it with a laser, and an imaging unit 531 that images the modified layer K in the wafer We from obliquely above based on the illumination light irradiated from the illumination unit 532. Furthermore, the control unit 7 acquires the shape of the modified layer K in the wafer We based on the imaging result of the modified layer K in the wafer We by the imaging unit 531.

[0057] Specifically, the control unit 7 controls the imaging unit 331 to capture images of the same position on the wafer We from multiple obliquely upward directions that are different from each other in a plan view, using the imaging unit 331. Furthermore, the control unit 7 acquires the three-dimensional shape of the modified layer K in the wafer We based on the imaging results of the modified layer K in the wafer We captured from multiple obliquely upward directions.

[0058] The control unit 7 also inspects the modified layer K for each street (the portion between adjacent semiconductor chips Ch) that divides the semiconductor chip Ch. The semiconductor chips Ch divided along the modified layer K have a substantially rectangular shape in a plan view. The streets are arranged to separate the rectangular semiconductor chips Ch.

[0059] The imaging unit 531 includes an area camera that captures images of a two-dimensional range, both vertically and horizontally. As shown in FIG. 10 , the imaging unit 531 includes an optical system having an imaging plane that satisfies the Scheimpflug condition for the surface of the wafer We. Specifically, the imaging unit 531 includes an imaging element 531a on which an image plane on which an image of the subject wafer We is formed is located, and an optical member 531b that focuses light on the imaging element 531a. The imaging element 531a includes an image sensor such as a CCD image sensor or a CMOS image sensor. The optical member 531b includes a lens. The imaging unit 531 is positioned such that its optical axis is inclined with respect to the horizontal plane so as to capture an image diagonally downward. The optical member 531b is positioned inclined (not perpendicular) to the optical axis of the imaging unit 531. In addition, the imaging unit 531 is configured so that the extensions of the subject plane, the lens main surface of the optical member 531b, and the image plane of the imaging element 531a intersect at one point C, and the entire image plane is in focus.

[0060] Since the imaging unit 531 satisfies the Scheimpflug condition, when imaging the wafer We from diagonally above, the influence of the optical path difference due to refraction between the wafer We and the air is reduced, thereby making it possible to prevent the image of the inside of the wafer We from becoming blurred.

[0061] The illumination unit 532 irradiates the wafer We with light having a wavelength in the near-infrared region. The imaging unit 531 has an imaging element 531a that can detect the illumination light having a wavelength in the near-infrared region irradiated from the illumination unit 532.

[0062] The dicing device 5 is provided with a rotation drive unit 54 (see FIG. 6 ) that rotates the wafer We around a vertical rotation axis. The rotation drive unit 54 rotates the wafer We when irradiating the wafer We with a laser to form a modified layer K. The rotation drive unit 54 also rotates the wafer We so that the imaging unit 531 can capture images of the wafer We from multiple directions after the modified layer K has been formed.

[0063] Specifically, the control unit 7 controls the imaging unit 331 to capture images of the modified layer K in the wafer We at multiple rotation angles at which the wafer We is rotated by the rotation drive unit 54.

[0064] 11, the imaging unit 331 is configured to capture images of each side of the rectangular semiconductor chip Ch from an oblique direction in a plan view. Note that the imaging unit 331 may capture images of each side of the rectangular semiconductor chip Ch from a direction parallel to or perpendicular to the side in a plan view.

[0065] (Example of modified layer inspection (first example)) As shown in Figure 12, the control unit 7 acquires the shape of the modified layer K within the wafer We based on multiple images taken of the same position on the wafer We from different directions in a planar view.

[0066] In the example shown in FIG. 12, the shape of the modified layer K is acquired based on four images taken from diagonally above the wafer We, that is, from the left side, right side, rear side, and front side in a plan view.

[0067] The control unit 7 estimates the position of the modified layer K on the A1-A1 side surface based on the imaging results captured from the left side. The control unit 7 estimates that the modified layer K is located on a diagonal line sloping downward to the right in a side view based on the imaging angle from diagonally above. The control unit 7 also estimates the position of the modified layer K on the A1-A1 side surface based on the imaging results captured from the right side. The control unit 7 estimates that the modified layer K is located on a diagonal line sloping upward to the right in a side view based on the imaging angle from diagonally above.

[0068] The control unit 7 superimposes a line that is estimated to indicate the presence of the modified layer K based on the imaging results taken from the left side and a line that is estimated to indicate the presence of the modified layer K based on the imaging results taken from the right side, and acquires the overlapping portion (AND composite) as the position where the modified layer K exists.

[0069] The control unit 7 estimates the position of the modified layer K on the A1-A1 side surface based on the imaging results captured from the back side. The control unit 7 estimates that the modified layer K is located on a line extending vertically in a side view based on the imaging angle from diagonally above. The control unit 7 also estimates the position of the modified layer K on the A1-A1 side surface based on the imaging results captured from the front side. The control unit 7 estimates that the modified layer K is located on a line extending vertically in a side view based on the imaging angle from diagonally above.

[0070] The control unit 7 superimposes a line that is estimated to indicate the presence of the modified layer K based on the imaging results taken from the back side and a line that is estimated to indicate the presence of the modified layer K based on the imaging results taken from the front side, and acquires the overlapping part (AND composite) as the position where the modified layer K exists.

[0071] The control unit 7 superimposes the position where the modified layer K is estimated to exist based on the imaging results taken from the left side and the imaging results taken from the right side, and the position where the modified layer K is estimated to exist based on the imaging results taken from the back side and the imaging results taken from the front side, and acquires the overlapping part (AND composite) as the position where the modified layer K is located.

[0072] As a result, the shape of the modified layer K in the wafer We is obtained.

[0073] (Example of modified layer inspection (second example)) As shown in Figures 13 and 14, the control unit 7 acquires the shape of the modified layer K within the wafer We based on multiple images taken of the same position on the wafer We from different directions in a planar view.

[0074] In this second example, the modified layer K is formed with its position shifted in the Y direction, as shown in Fig. 13. Images of this modified layer K are taken from directions B1, B2, B3, and B4, which are different from one another.

[0075] As shown in FIG. 14, the shape of the modified layer K in the wafer We can be obtained by combining images captured in the B1 direction, the B2 direction, the B3 direction, and the B4 direction.

[0076] The control unit 7 performs an inspection based on the acquired shape of the modified layer K. For example, the control unit 7 inspects whether the planar position of the modified layer K is within a predetermined range. The control unit 7 also inspects whether the height position of the modified layer K is within a predetermined range. The control unit 7 also inspects whether the width of the modified layer K in a planar view is within a predetermined range. The control unit 7 also inspects whether the length of the modified layer K in the height direction is within a predetermined range. The control unit 7 also inspects whether the formation position of the modified layer K is located at a distance within a predetermined range from the front or back surface of the wafer We.

[0077] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0078] As described above, this embodiment is provided with the imaging unit 331 that images the modified layer K in the wafer We from diagonally above, and the control unit 7 that acquires the shape of the modified layer K in the wafer We based on the image of the modified layer K in the wafer We captured by the imaging unit 331. This allows the vertical shape of the modified layer K in the wafer We to be acquired by capturing the image from diagonally above by the imaging unit 331, so the vertical state of the modified layer K in the wafer We can be acquired with high accuracy. As a result, the state of the modified layer K formed on the wafer We can be inspected with high accuracy.

[0079] Furthermore, in this embodiment, as described above, the control unit 7 controls the imaging unit 331 to capture images of the same position on the wafer We from multiple obliquely upward directions that are different from each other in a plan view, and acquires the three-dimensional shape of the modified layer K in the wafer We based on the image capture results of the modified layer K in the wafer We captured from multiple obliquely upward directions. As a result, by performing a composite operation on the images of the modified layer K in the wafer We captured from multiple obliquely upward directions that are different from each other in a plan view, the three-dimensional shape of the modified layer K in the wafer We can be acquired with high accuracy, and the state of the modified layer K formed on the wafer We can be inspected with high accuracy.

[0080] Furthermore, in this embodiment, as described above, the semiconductor chips Ch separated from the wafer We along the modified layers K have a rectangular shape in a plan view, and the imaging unit 331 is configured to image each side of the rectangular semiconductor chip Ch from an oblique direction in a plan view. This allows multiple modified layers K formed along two mutually perpendicular sides of the rectangular semiconductor chip Ch in a plan view to be simultaneously imaged from above at an oblique angle, thereby preventing the number of times the modified layers K are imaged from increasing. As a result, the modified layers K can be inspected efficiently.

[0081] Furthermore, in this embodiment, as described above, the rotation drive unit 54 is provided to rotate the wafer We around the vertical rotation axis. Furthermore, the control unit 7 controls the imaging unit 331 to capture images of the modified layer K in the wafer We at multiple rotation angles to which the wafer We is rotated by the rotation drive unit 54. This allows the common imaging unit 331 to capture images of the modified layer K in the wafer We from multiple angles, making it possible to more accurately inspect the state of the modified layer K formed on the wafer We without increasing the number of imaging units 331.

[0082] Furthermore, in this embodiment, as described above, the imaging unit 331 includes an optical system having an imaging plane that satisfies the Scheimpflug condition for the surface of the wafer We. As a result, by imaging the wafer We from diagonally above, the focal position of the imaging unit 331 can be adjusted even when the distance between the imaging unit 331 and the surface of the wafer We varies depending on the position of the wafer We. This makes it possible to prevent the image of the modified layer K in the wafer We imaged from diagonally above from becoming blurred.

[0083] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0084] For example, in the above-described embodiment, an example of a configuration in which the imaging unit captures images of the modified layer in the wafer at multiple rotation angles when the wafer is rotated by the rotation drive unit has been described, but the present invention is not limited to this. In the present invention, as shown in the example of FIG. 15 , the modified layer in the wafer may be captured using an imaging unit 81 capable of capturing images from multiple directions, including above and diagonally above. That is, the imaging unit 81 is configured to simultaneously capture images from multiple directions from diagonally above, and the control unit 7 controls the imaging unit 81 to capture images of the modified layer K in the wafer We from multiple diagonally above directions. This allows the modified layer K in the wafer We to be captured simultaneously from multiple angles, thereby more accurately inspecting the state of the modified layer K formed on the wafer We while minimizing the time required to capture the modified layer K in the wafer We.

[0085] The imaging unit 81 is configured to image the wafer We from diagonally above and from above. The control unit 7 acquires the shape of the modified layer K in the wafer We based on the results of imaging the modified layer K in the wafer from diagonally above and from above by the imaging unit 81. As a result, by imaging the modified layer K in the wafer We from above as well, the shape of the modified layer K in the wafer We in a planar view can be acquired with high accuracy, and the state of the modified layer K formed on the wafer We can be inspected with high accuracy.

[0086] In addition, in a configuration in which the imaging unit 81 can simultaneously capture images from multiple directions from diagonally above, multiple cameras 811, 812, 813, and 814 may be provided so that the imaging directions are different from each other, as shown in Fig. 15. Alternatively, a common camera may be provided, and the field of view may be divided by an optical system including mirrors and lenses, so that images are captured simultaneously from multiple imaging directions by the common camera (image sensor).

[0087] In the above embodiment, an example of a configuration in which the imaging unit that images the modified layer in the wafer is provided in the dicing device that forms the modified layer has been shown, but the present invention is not limited to this. In the present invention, the imaging unit that images the modified layer in the wafer may be provided in a post-dicing (post-modified layer formation) inspection device that is provided separately from the dicing device.

[0088] In the above embodiment, an example of a configuration in which the imaging unit that images the modified layer in the wafer is fixedly provided has been shown, but the present invention is not limited to this. In the present invention, the imaging unit that images the modified layer in the wafer may be provided so as to be movable above the wafer.

[0089] In the above embodiment, an example of a configuration in which the imaging unit that images the modified layer in the wafer images the same position on the wafer from multiple obliquely above positions has been shown, but the present invention is not limited to this. In the present invention, inspection may be performed by imaging the same position on the wafer from a single obliquely above position.

[0090] In the above embodiment, an example of a configuration in which the imaging unit that images the modified layer in the wafer satisfies the Scheimpflug condition has been described, but the present invention is not limited to this. In the present invention, the imaging unit that images the modified layer in the wafer may be an imaging unit that does not satisfy the Scheimpflug condition and performs imaging such that the imaging plane is a plane perpendicular to the optical axis.

[0091] In the above embodiment, the imaging unit that captures the modified layer in the wafer includes an area camera that captures a surface, but the present invention is not limited to this. In the present invention, the imaging unit that captures the modified layer in the wafer may include a line camera. In this case, the line camera does not need to satisfy the Scheimpflug condition.

[0092] 5 Dicing device (wafer inspection device) 7 Control unit 54 Rotation drive unit 531 Imaging unit 532 Illumination unit Ch Semiconductor chip K Modified layer We Wafer

Claims

1. An illumination unit that irradiates illumination light toward the modified layer of a wafer in which a modified layer is formed inside by irradiating a laser; an imaging unit that images the modified layer in the wafer from obliquely above based on the illumination light irradiated from the illumination unit; and a control unit that acquires the shape of the modified layer in the wafer based on the imaging result of the modified layer in the wafer by the imaging unit. A wafer inspection apparatus comprising:

2. The control unit controls the imaging unit to image the same position of the wafer from a plurality of obliquely above directions that are different from each other in a plan view, and based on the imaging results of the modified layer in the wafer imaged from a plurality of obliquely above directions, the wafer inspection apparatus according to claim 1, which acquires a three-dimensional shape of the modified layer in the wafer.

3. The semiconductor chip divided from the wafer along the modified layer has a rectangular shape in a plan view, and the imaging unit is configured to image each side of the rectangular semiconductor chip from an oblique direction in a plan view. The wafer inspection apparatus according to claim 1.

4. The wafer inspection apparatus according to claim 2, further comprising a rotation driving unit that rotates the wafer around a vertical rotation axis, and the control unit controls the imaging unit to image the modified layer in the wafer at a plurality of rotation angles at which the wafer is rotated by the rotation driving unit.

5. The imaging unit is configured to be able to image simultaneously from a plurality of directions obliquely above, and the control unit controls the imaging unit to image the modified layer in the wafer from a plurality of directions obliquely above. The wafer inspection apparatus according to claim 2.

6. The imaging unit is configured to image the wafer from obliquely above and above, and the control unit acquires the shape of the modified layer in the wafer based on the imaging results of the modified layer in the wafer from obliquely above and above by the imaging unit. The wafer inspection apparatus according to claim 1.

7. The imaging unit includes an optical system having an imaging surface that satisfies the specular-proof condition with respect to the surface of the wafer. The wafer inspection apparatus according to claim 1.

8. Irradiate illumination light toward the modified layer of a wafer in which a modified layer is formed inside by irradiating a laser, image the modified layer in the wafer from obliquely above based on the illumination light by an imaging unit, and acquire the shape of the modified layer in the wafer based on the imaging result of the modified layer in the wafer by the imaging unit. A wafer inspection method.

9. Imaging the modified layer by the imaging unit includes imaging the same position of the wafer from a plurality of obliquely above directions that are different from each other in a plan view, and acquiring the shape of the modified layer in the wafer includes acquiring the three-dimensional shape of the modified layer in the wafer based on the imaging results of the modified layer in the wafer imaged from obliquely above in a plurality of directions. The wafer inspection method according to claim 8.

Images