Laser processing method, semiconductor device manufacturing method, and inspection apparatus

Abstract

The inspection apparatus of the present invention comprises: a stage for supporting a wafer in which a plurality of rows of modified regions are formed inside a semiconductor substrate; a light source that outputs light that is transmissive to the semiconductor substrate; an objective lens that transmits light propagating in the semiconductor substrate; a light detection unit that detects light transmitted from the objective lens; and an inspection unit that inspects a tip position of a crack extending from the modified region closest to the back surface to the back surface side in an inspection region between the modified region closest to the back surface of the semiconductor substrate and the back surface, the objective lens being focused into the inspection region from the back surface side. The light detection unit detects light propagating in the semiconductor substrate from the front surface side to the back surface side of the semiconductor substrate.

Description

[0001] This application is filed on October 2, 2019 、Application No. 201980065075.9 、The name of the invention is Laser Add Process, semiconductor device manufacturing method and inspection device A divisional application for a patent application. Technical Field

[0002] The present invention relates to a laser processing method, a semiconductor device manufacturing method and an inspection device. Background Art

[0003] A laser processing device is known, which irradiates a wafer with laser light from the back side of a semiconductor substrate to cut a wafer including a semiconductor substrate and a functional element layer formed on the front side of the semiconductor substrate along a plurality of lines, thereby forming a plurality of rows of modified regions inside the semiconductor substrate along the plurality of lines. The laser processing device described in Patent Document 1 includes an infrared camera, which can observe the modified regions formed inside the semiconductor substrate and processing damage formed on the functional element layer from the back side of the semiconductor substrate.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-64746 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In the above-mentioned laser processing device, a laser is irradiated to the wafer from the back side of the semiconductor substrate under the condition of forming cracks across multiple rows of modified regions. In such a case, if the cracks across multiple rows of modified regions do not extend sufficiently to the front side of the semiconductor substrate due to, for example, the poor state of the laser processing device, the wafer may not be reliably cut along multiple lines in the subsequent steps. In particular, when the back side of the semiconductor substrate is ground after the formation of the modified region, if it cannot be confirmed before the grinding step whether the cracks across multiple rows of modified regions extend sufficiently to the front side of the semiconductor substrate, the wafer may not be reliably cut along multiple lines after the grinding step, and the grinding step is wasted.

[0009] It is difficult to confirm whether the cracks across multiple rows of modified regions have fully extended to the front side of the semiconductor substrate by only observing the modified regions. Although cracks across multiple rows of modified regions can be observed, the width of the cracks is usually smaller than the wavelength of infrared light, so it is difficult to observe the cracks using only an infrared camera.

[0010] The present invention aims to provide a laser processing method, a semiconductor device manufacturing method and an inspection apparatus capable of confirming whether a crack spanning multiple rows of reformed regions has sufficiently extended to the front side of a semiconductor substrate.

[0011] Technical solutions to solve problems

[0012] A laser processing method according to one embodiment of the present invention comprises: a first step of preparing a chip including a semiconductor substrate having a front side and a back side and a functional element layer formed on the front side, and irradiating the chip with a laser from the back side along a plurality of lines to form a plurality of rows of modified regions inside the semiconductor substrate along the plurality of lines; and a second step of inspecting the front end position of a crack extending from the modified region closest to the back side to the back side in an inspection area between a modified region closest to the back side among the plurality of rows of modified regions and the back side, wherein in the first step, the chip is irradiated with a laser from the back side along a plurality of lines to form a crack spanning a plurality of rows of modified regions, and in the second step, the front end position is inspected by focusing on the inspection area from the back side and detecting light propagating from the front side to the back side in the semiconductor substrate.

[0013] In the laser processing method, the light propagating from the front side to the back side in the semiconductor substrate is detected by focusing from the back side of the semiconductor substrate to the inspection area between the modified area closest to the back side of the semiconductor substrate and the back side. By detecting the light in this way, the front end position of the crack extending from the modified area closest to the back side to the back side of the semiconductor substrate can be confirmed in the inspection area. Moreover, when the front end position of the crack is located on the front side of the semiconductor substrate relative to the reference position between the modified area closest to the back side of the semiconductor substrate and the back side, it is expected that the crack across multiple rows of modified areas is not fully extended to the front side of the semiconductor substrate. Therefore, according to the laser processing method, it is possible to confirm whether the crack across multiple rows of modified areas has fully extended to the front side of the semiconductor substrate.

[0014] In the laser processing method of one embodiment of the present invention, in step 1, the wafer may be irradiated with laser light along a plurality of lines from the back side under the condition that cracks across a plurality of rows of modified regions reach the front side. This makes it possible to confirm whether cracks across a plurality of rows of modified regions reach the front side of the semiconductor substrate.

[0015] The laser processing method of one embodiment of the present invention may further include a third step of evaluating the processing result of the first step based on the inspection result of the second step, wherein in the third step, when the front end position is located on the back side relative to the reference position between the modified region closest to the back and the back, it is evaluated that the crack across the multiple rows of modified regions has reached the front side, and when the front end position is located on the front side relative to the reference position, it is evaluated that the crack across the multiple rows of modified regions has not reached the front side. Thus, the implementation of the subsequent steps can be determined based on the evaluation results.

[0016] In the laser processing method of one embodiment of the present invention, the inspection area is an area extending from the reference position to the back side and not reaching the back side. In the third step, when the front end position is located in the inspection area, it is evaluated that the crack across multiple rows of modified regions has reached the front side, and when the front end position is not located in the inspection area, it is evaluated that the crack across multiple rows of modified regions has not reached the front side. The front end position of the crack is more stable when the crack across multiple rows of modified regions reaches the front side of the semiconductor substrate than when the crack across multiple rows of modified regions does not reach the front side of the semiconductor substrate. Therefore, by setting the area extending from the reference position to the back side of the semiconductor substrate and not reaching the back side as the inspection area, the inspection of cracks across multiple rows of modified regions can be effectively implemented.

[0017] In the laser processing method of one embodiment of the present invention, the multiple rows of reformed regions may be two rows of reformed regions. This allows efficient formation of multiple rows of reformed regions and inspection of cracks spanning multiple rows of reformed regions.

[0018] A semiconductor device manufacturing method according to one embodiment of the present invention comprises: the first step, the second step and the third step included in the above-mentioned laser processing method; and the fourth step, in which, when it is evaluated in the third step that the cracks spanning multiple rows of modified regions have reached the front side, the back side is polished to expose the cracks spanning multiple rows of modified regions to the back side, and the wafer is cut into multiple semiconductor devices along multiple lines respectively.

[0019] According to the semiconductor device manufacturing method, when a crack that is evaluated to span multiple rows of modified regions has not reached the front side of the semiconductor substrate, grinding of the back side of the semiconductor substrate is not performed. This can prevent the situation in which the chip cannot be reliably cut along multiple lines after the grinding step.

[0020] In the semiconductor device manufacturing method according to one embodiment of the present invention, the back surface may be ground at least to a reference position in the fourth step. This allows the wafer to be reliably cut along each of the plurality of lines.

[0021] An inspection device according to one embodiment of the present invention comprises: a platform for supporting a chip, the chip comprising a semiconductor substrate having a front side and a back side and a functional element layer formed on the front side, and a plurality of rows of modified regions are formed inside the semiconductor substrate along a plurality of lines respectively; a light source for outputting light that is transmissive to the semiconductor substrate; an objective lens for transmitting light output from the light source and propagating in the semiconductor substrate; a light detection unit for detecting light transmitted from the objective lens; and an inspection unit, which inspects the front end position of a crack extending from a modified region closest to the back side in an inspection area between a modified region closest to the back side among the plurality of rows of modified regions and the back side based on a signal output from the light detection unit, the objective lens is focused from the back side to the inspection area, and the light detection unit detects light propagating from the front side to the back side in the semiconductor substrate.

[0022] The inspection device detects light propagating from the front side of the semiconductor substrate to the back side in an inspection area between a modified area closest to the back side of the semiconductor substrate and the back side. By detecting light in this way, the front end position of a crack extending from the modified area closest to the back side to the back side of the semiconductor substrate can be confirmed in the inspection area.

[0023] In the inspection device according to one embodiment of the present invention, the numerical aperture of the objective lens may be 0.45 or more. This allows the tip position of the crack to be more reliably confirmed in the inspection region.

[0024] In the inspection device according to one embodiment of the present invention, the objective lens may include a correction ring. This allows the tip position of the crack to be more reliably confirmed in the inspection region.

[0025] Effects of the Invention

[0026] According to the present invention, a laser processing method, a semiconductor device manufacturing method, and an inspection apparatus capable of confirming whether a crack spanning a plurality of rows of reformed regions has sufficiently extended to the front surface side of a semiconductor substrate can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a configuration diagram of a laser processing device including an inspection device according to one embodiment.

[0028] Figure 2 This is a plan view of a wafer according to one embodiment.

[0029] Figure 3 yes Figure 2 A cross-sectional view of a portion of a wafer is shown.

[0030] Figure 4 yes Figure 1 The structure diagram of the laser irradiation unit shown.

[0031] Figure 5 yes Figure 1 The structure diagram of the inspection imaging unit shown.

[0032] Figure 6 yes Figure 1 The configuration diagram of the imaging unit for alignment correction is shown.

[0033] Figure 7 It is used to illustrate Figure 5 A cross-sectional view of a wafer showing the imaging principle of the inspection imaging unit and images of various locations obtained by the inspection imaging unit.

[0034] Figure 8 It is used to illustrate Figure 5 A cross-sectional view of a wafer showing the imaging principle of the inspection imaging unit and images of various locations obtained by the inspection imaging unit.

[0035] Fig. 9 This is a SEM image of a modified region and cracks formed inside a semiconductor substrate.

[0036] Fig.10 This is a SEM image of a modified region and cracks formed inside a semiconductor substrate.

[0037] Fig.11 It is used to illustrate Figure 5 The optical path diagram of the imaging principle of the inspection imaging unit shown, and the schematic diagram showing the image at the focus of the inspection imaging unit.

[0038] Fig.12 It is used to illustrate Figure 5 The optical path diagram of the imaging principle of the inspection imaging unit shown, and the schematic diagram showing the image at the focus of the inspection imaging unit.

[0039] Fig.13 It is used to illustrate Figure 5 The inspection principle of the inspection imaging unit shown is a cross-sectional view of a wafer, an image of a cut surface of the wafer, and images of various locations obtained by the inspection imaging unit.

[0040] Fig.14 It is used to illustrate Figure 5 The inspection principle of the inspection imaging unit shown is a cross-sectional view of a wafer, an image of a cut surface of the wafer, and images of various locations obtained by the inspection imaging unit.

[0041] Fig.15 This is a flowchart of a method for manufacturing a semiconductor device according to one embodiment.

[0042] Fig.16 yes Fig.15A cross-sectional view of a portion of a wafer during the grinding and cutting steps of the semiconductor device manufacturing method is shown.

[0043] Fig.17 yes Fig.15 A cross-sectional view of a portion of a wafer during the grinding and cutting steps of the semiconductor device manufacturing method is shown.

[0044] Fig.18 This is a diagram showing the structure of a laser processing system including an inspection device according to a modified example. DETAILED DESCRIPTION

[0045] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are given to the same or corresponding parts, and repeated descriptions are omitted.

[0046] [Configuration of laser processing equipment]

[0047] like Figure 1 As shown, the laser processing apparatus 1 includes a stage 2, a laser irradiation unit 3, a plurality of imaging units 4, 5, 6, a drive unit 7, and a control unit 8. The laser processing apparatus 1 is an apparatus for forming a modified region 12 in an object 11 by irradiating the object 11 with laser light L.

[0048] The mounting table 2 supports the object 11 by, for example, adsorbing a film attached to the object 11. The mounting table 2 can move in the X direction and the Y direction, respectively, and can rotate around an axis parallel to the Z direction as a center line. The X direction and the Y direction are the first horizontal direction and the second horizontal direction perpendicular to each other, and the Z direction is the vertical direction.

[0049] The laser irradiation unit 3 focuses the laser light L having transmittance to the object 11 and irradiates the object 11. When the laser light L is focused inside the object 11 supported by the mounting table 2, the laser light L is particularly absorbed in the portion corresponding to the focusing point C of the laser light L, and a modified region 12 can be formed inside the object 11.

[0050] The modified region 12 is a region whose density, refractive index, mechanical strength or other physical properties are different from those of the surrounding non-modified region. Examples of the modified region 12 include a melt-processed region, a crack region, an insulation breakdown region, and a refractive index change region. The modified region 12 has a characteristic that cracks easily extend from the modified region 12 to the incident side of the laser L and the opposite side thereof. Such characteristics of the modified region 12 are utilized for cutting the object 11.

[0051] As an example, when the stage 2 is moved in the X direction and the focal point C is moved relative to the object 11 in the X direction, a plurality of modified points 12s are formed in a row in the X direction. One modified point 12s is formed by irradiation with one pulse of laser light L. One row of modified regions 12 is a collection of a plurality of modified points 12s arranged in a row. Adjacent modified points 12s may be connected to each other or separated from each other depending on the relative moving speed of the focal point C relative to the object 11 and the repetition frequency of the laser light L.

[0052] The imaging unit 4 captures the modified region 12 formed in the object 11 and the tip of the crack extending from the modified region 12. In this embodiment, the control unit 8 functions as an inspection unit, and the mounting table 2, the imaging unit 4 and the control unit 8 function as an inspection device 10 (details will be described later).

[0053] The imaging units 5 and 6 capture an image of the object 11 supported by the mounting table 2 using light transmitted through the object 11 under the control of the control unit 8. The images captured by the imaging units 5 and 6 are used to align the irradiation position of the laser light L, for example.

[0054] The driving unit 7 supports the laser irradiation unit 3 and the plurality of imaging units 4, 5, and 6. The driving unit 7 moves the laser irradiation unit 3 and the plurality of imaging units 4, 5, and 6 in the Z direction.

[0055] The control unit 8 controls the operation of the mounting table 2, the laser irradiation unit 3, the plurality of imaging units 4, 5, 6, and the driving unit 7. The control unit 8 is configured as a computer device including a processor, a memory, a storage, and a communication device. In the control unit 8, the processor executes the software (program) read from the memory, etc., controls the reading or writing of data in the memory and the storage, and the communication performed by the communication device. Thus, the control unit 8 realizes the function of, for example, an inspection unit (details will be described later).

[0056] [Composition of the object]

[0057] The object 11 of this embodiment is as follows Figure 2 and Figure 3The wafer 20 is shown. The wafer 20 includes a semiconductor substrate 21 and a functional element layer 22. The semiconductor substrate 21 has a front side 21a and a back side 21b. The semiconductor substrate 21 is, for example, a silicon substrate. The functional element layer 22 is formed on the front side 21a of the semiconductor substrate 21. The functional element layer 22 includes a plurality of functional elements 22a arranged two-dimensionally along the front side 21a. The functional element 22a is, for example, a light-receiving element such as a light-emitting diode, a light-emitting element such as a laser diode, a circuit element such as a memory, and the like. The functional element 22a may also be three-dimensionally constructed by stacking a plurality of layers. In addition, although a notch 21c indicating a crystal orientation is provided in the semiconductor substrate 21, an orientation plane may be provided instead of the notch 21c.

[0058] The wafer 20 is cut along the plurality of lines 15 for each functional element 22a. When the plurality of lines 15 are observed from the thickness direction of the wafer 20, they pass between each of the plurality of functional elements 22a. More specifically, when the line 15 is observed from the thickness direction of the wafer 20, it passes through the center (center in the width direction) of the grid line area 23. The grid line area 23 extends in the functional element layer 22 in a manner passing between adjacent functional elements 22a. In the present embodiment, the plurality of functional elements 22a are arranged in a matrix along the front surface 21a, and the plurality of lines 15 are set in a grid shape. In addition, although the lines 15 are virtual lines, they may also be actually drawn lines.

[0059] [Configuration of laser irradiation unit]

[0060] like Figure 4 As shown, the laser irradiation unit 3 includes a light source 31, a spatial light modulator 32, and a focusing lens 33. The light source 31 outputs laser light L by, for example, a pulse oscillation method. The spatial light modulator 32 modulates the laser light L output from the light source 31. The spatial light modulator 32 is, for example, a spatial light modulator (SLM: Spatial Light Modulator) of a reflective liquid crystal (LCOS: Liquid Crystal on Silicon). The focusing lens 33 focuses the laser light L modulated by the spatial light modulator 32.

[0061] In the present embodiment, the laser irradiation unit 3 irradiates the wafer 20 with laser light L from the back surface 21b side of the semiconductor substrate 21 along the plurality of lines 15, thereby forming two rows of modified regions 12a and 12b inside the semiconductor substrate 21 along the plurality of lines 15. The modified region (first modified region) 12a is the modified region closest to the front surface 21a of the two rows of modified regions 12a and 12b. The modified region (second modified region) 12b is the modified region closest to the modified region 12a of the two rows of modified regions 12a and 12b, and is also the modified region closest to the back surface 21b.

[0062] The two rows of modified regions 12a and 12b are adjacent to each other in the thickness direction (Z direction) of the wafer 20. The two rows of modified regions 12a and 12b are formed by relatively moving the two focal points C1 and C2 along the line 15 with respect to the semiconductor substrate 21. The laser light L is modulated by the spatial light modulator 32 so that, for example, the focal point C2 is located at the rear side of the traveling direction relative to the focal point C1 and at the incident side of the laser light L.

[0063] The laser irradiation unit 3 irradiates the wafer 20 with laser light L along the plurality of lines 15 from the back side 21b of the semiconductor substrate 21 under the condition that the cracks 14 across the two rows of reformed regions 12a and 12b reach the front side 21a of the semiconductor substrate 21. As an example, for the semiconductor substrate 21 which is a single crystal silicon substrate with a thickness of 775 μm, the two focal points C1 and C2 are focused at the positions 54 μm and 128 μm away from the front side 21a, respectively, and the wafer 20 is irradiated with laser light L along the plurality of lines 15 from the back side 21b of the semiconductor substrate 21. At this time, the wavelength of the laser light L is 1099 nm, the pulse width is 700 nsec, and the repetition frequency is 120 kHz. In addition, the output of the laser light L at the focal point C1 is 2.7 W, the output of the laser light L at the focal point C2 is 2.7 W, and the relative moving speed of the two focal points C1 and C2 with respect to the semiconductor substrate 21 is 800 mm / sec.

[0064] The formation of the two rows of modified regions 12a, 12b and the cracks 14 is carried out in the following case. That is, in a subsequent step, the back surface 21b of the semiconductor substrate 21 is polished to thin the semiconductor substrate 21, and the cracks 14 are exposed on the back surface 21b, and the wafer 20 is cut into a plurality of semiconductor devices along the plurality of lines 15.

[0065] [Composition of the inspection camera unit]

[0066] like Figure 5 As shown in FIG. 1 , the imaging unit 4 includes a light source 41, a reflector 42, an objective lens 43, and a light detection unit 44. The light source 41 outputs light I1 having transmissivity to the semiconductor substrate 21. The light source 41 is composed of, for example, a halogen lamp and a filter, and outputs light I1 in the near-infrared region. The light I1 output from the light source 41 is reflected by the reflector 42 and passes through the objective lens 43, and is irradiated to the wafer 20 from the back surface 21b side of the semiconductor substrate 21. At this time, the mounting table 2 supports the wafer 20 on which the two rows of modified regions 12a and 12b are formed as described above.

[0067] The objective lens 43 allows the light I1 reflected by the front surface 21a of the semiconductor substrate 21 to pass. That is, the objective lens 43 allows the light I1 propagated in the semiconductor substrate 21 to pass. The numerical aperture (NA) of the objective lens 43 is greater than 0.45. The objective lens 43 has a correction ring 43a. The correction ring 43a corrects the aberration caused by the light I1 in the semiconductor substrate 21, for example, by adjusting the distance between the multiple lenses constituting the objective lens 43. The light detection unit 44 detects the light I1 transmitted through the objective lens 43 and the reflector 42. The light detection unit 44 is composed of, for example, an InGaAs camera, and detects the light I1 in the near-infrared region.

[0068] The camera unit 4 can capture each of the two rows of modified regions 12a, 12b, and the front ends of the plurality of cracks 14a, 14b, 14c, and 14d (details will be described later). The crack 14a is a crack extending from the modified region 12a to the front side 21a. The crack 14b is a crack extending from the modified region 12a to the back side 21b. The crack 14c is a crack extending from the modified region 12b to the front side 21a. The crack 14d is a crack extending from the modified region 12b to the back side 21b. The control unit 8 causes the laser irradiation unit 3 to irradiate the laser L (see FIG. 1 ) under the condition that the crack 14 spanning the two rows of modified regions 12a, 12b reaches the front side 21a of the semiconductor substrate 21. Figure 4 ), but when the crack 14 does not reach the front side 21a due to some abnormality, a plurality of such cracks 14a, 14b, 14c, 14d will be formed.

[0069] [Configuration of the image pickup unit for alignment correction]

[0070] like Figure 6 As shown, the imaging unit 5 includes a light source 51, a reflector 52, a lens 53, and a light detection unit 54. The light source 51 outputs light I2 that is transmissive to the semiconductor substrate 21. The light source 51 is composed of, for example, a halogen lamp and a filter, and outputs light I2 in the near-infrared region. The light source 51 may also be common to the light source 41 of the imaging unit 4. The light I2 output from the light source 51 is reflected by the reflector 52 and passes through the lens 53, and is irradiated to the wafer 20 from the back side 21b of the semiconductor substrate 21.

[0071] The lens 53 allows the light I2 reflected by the front surface 21a of the semiconductor substrate 21 to pass through. That is, the lens 53 allows the light I2 propagated in the semiconductor substrate 21 to pass through. The numerical aperture of the lens 53 is less than 0.3. That is, the numerical aperture of the objective lens 43 of the imaging unit 4 is larger than the numerical aperture of the lens 53. The light detection unit 54 detects the light I2 passing through the lens 53 and the reflector 52. The light detection unit 54 is composed of, for example, an InGaAs camera, and detects the light I2 in the near-infrared region.

[0072] The imaging unit 5, under the control of the control unit 8, irradiates the wafer 20 with light I2 from the back side 21b, and detects the light I2 returned from the front side 21a (functional element layer 22), thereby photographing the functional element layer 22. Also, the imaging unit 5, under the control of the control unit 8, irradiates the wafer 20 with light I2 from the back side 21b, and detects the light I2 returned from the formation position of the modified regions 12a and 12b of the semiconductor substrate 21, thereby acquiring an image of the region including the modified regions 12a and 12b. These images are used to align the irradiation position of the laser L. The imaging unit 6 has the same configuration as the imaging unit 5, except that the magnification is low compared to the lens 53 (for example, 6 times in the imaging unit 5 and 1.5 times in the imaging unit 6), and is used for alignment in the same manner as the imaging unit 5.

[0073] [Image capture principle of the inspection image capture unit]

[0074] use Figure 5 The camera unit 4 shown in FIG. Figure 7 As shown in FIG. 1 , for a semiconductor substrate 21 in which a crack 14 extending across two rows of reformed regions 12a and 12b reaches the front surface 21a, the focus F (the focus of the objective lens 43) is moved from the back surface 21b side to the front surface 21a side. In this case, if the focus F is focused from the back surface 21b side to the front end 14e of the crack 14 extending from the reformed region 12b to the back surface 21b side, it can be confirmed that the front end 14e ( Figure 7 However, even if the focus is adjusted from the back side 21b to the crack 14 itself and the front end 14e of the crack 14 that has reached the front side 21a, it cannot be confirmed ( Figure 7 In addition, if the focus F is adjusted from the back surface 21b side to the front surface 21a of the semiconductor substrate 21, the functional element layer 22 can be confirmed.

[0075] And, use Figure 5 The camera unit 4 shown in FIG. Figure 8 As shown in FIG. 1 , for a semiconductor substrate 21 in which a crack 14 extending across two rows of reformed regions 12a and 12b does not reach the front surface 21a, the focus F is moved from the back surface 21b side to the front surface 21a side. In this case, even if the focus F is focused from the back surface 21b side to the front end 14e of the crack 14 extending from the reformed region 12a to the front surface 21a side, the front end 14e cannot be confirmed ( Figure 8 However, if the focus F is focused from the back side 21b to the area on the opposite side of the back side 21b relative to the front side 21a (i.e., the area on the functional element layer 22 side relative to the front side 21a), and a virtual focus Fv symmetrical to the focus F with respect to the front side 21a is positioned at the front end 14e, it can be confirmed that the front end 14e ( Figure 8In addition, the virtual focus Fv is a point symmetrical to the focus F about the front surface 21a in consideration of the refractive index of the semiconductor substrate 21.

[0076] The reason why the crack 14 could not be confirmed as described above is presumably because the width of the crack 14 is smaller than the wavelength of the light I1 as the illumination light. Fig. 9 and Fig.10 This is a SEM (Scanning Electron Microscope) image of a reformed region 12 and a crack 14 formed inside a semiconductor substrate 21 which is a silicon substrate. Fig. 9 (b) is Fig. 9 The enlarged image of the area A1 shown in (a) is Fig.10 (a) is Fig. 9 (b) shows an enlarged image of region A2, Fig.10 (b) is Fig.10 This is an enlarged image of the region A3 shown in (a) of FIG. 1. As described above, the width of the crack 14 is about 120 nm, which is smaller than the wavelength (for example, 1.1 to 1.2 μm) of the light I1 in the near-infrared region.

[0077] The imaging principle envisioned based on the above matters is as follows. Fig.11 As shown in (a), if the focus F is placed in the air, the light I1 will not return, so a dark image will be obtained ( Fig.11 (a) is the image on the right side of the image). Fig.11 As shown in (b), if the focus F is located inside the semiconductor substrate 21, the light I1 reflected by the front surface 21a will return, so a white image will be obtained ( Fig.11 (b) is the image on the right side of the image). Fig.11 As shown in (c), if the focus F is focused on the modified region 12 from the back side 21b, a part of the light I1 reflected and returned by the front side 21a is absorbed or scattered by the modified region 12, so an image showing the modified region 12 as dark against a white background is obtained ( Fig.11 (c) is the right image of the image).

[0078] like Fig.12 As shown in (a) and (b), if the focus F is focused from the back side 21b to the front end 14e of the crack 14, the light will be confined near the front end 14e due to, for example, optical specificity (stress concentration, distortion, discontinuity of atomic density, etc.) generated near the front end 14e, thereby causing part of the light I1 reflected by the front side 21a to be scattered, reflected, interfered, absorbed, etc., so that an image showing the dark front end 14e against a white background is obtained ( Fig.12 (a) and (b) on the right). Fig.12As shown in (c), if the focus F is focused from the back side 21b to the portion other than the vicinity of the front end 14e of the crack 14, at least a portion of the light I1 reflected by the front side 21a will return, so a white image will be obtained ( Fig.12 (c) is the right image of the image).

[0079] [Inspection principle of the inspection camera unit]

[0080] The control unit 8 irradiates the laser L to the laser irradiation unit 3 under the condition that the crack 14 across the two rows of modified regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21. As a result, when the crack 14 across the two rows of modified regions 12a and 12b reaches the front surface 21a, the state of the front end 14e of the crack 14 is as follows. That is, Fig.13 As shown, the front end 14e of the crack 14 does not appear in the area between the modified region 12a and the front surface 21a, and in the area between the modified region 12a and the modified region 12b. The position of the front end 14e of the crack 14 extending from the modified region 12b to the back surface 21b side (hereinafter referred to as "front end position") is located on the back surface 21b side relative to the reference position P between the modified region 12b and the back surface 21b.

[0081] In contrast, the control unit 8 irradiates the laser light L to the laser irradiation unit 3 under the condition that the crack 14 across the two rows of modified regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21. As a result, contrary to the expectation, the crack 14 across the two rows of modified regions 12a and 12b does not reach the front surface 21a due to some poor conditions, and the state of the front end 14e of the crack 14 becomes as follows. That is, Fig.14 As shown, the front end 14e of the crack 14a extending from the modified region 12a to the front side 21a appears in the region between the modified region 12a and the front side 21a. The front end 14e of the crack 14b extending from the modified region 12a to the back side 21b and the front end 14e of the crack 14c extending from the modified region 12b to the front side 21a appear in the region between the modified region 12a and the modified region 12b. The front end position of the crack 14d extending from the modified region 12b to the back side 21b is located at the front side 21a relative to the reference position P between the modified region 12b and the back side 21b.

[0082] Due to the above, if the control unit 8 performs at least one of the first inspection, the second inspection, the third inspection, and the fourth inspection, it is possible to evaluate whether the crack 14 across the two rows of modified regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21. The first inspection is to set the area between the modified region 12a and the front surface 21a as the inspection area R1, and to check whether the front end 14e of the crack 14a extending from the modified region 12a to the front surface 21a side exists in the inspection area R1. The second inspection is to set the area between the modified region 12a and the modified region 12b as the inspection area R2, and to check whether the front end 14e of the crack 14b extending from the modified region 12a to the back surface 21b side exists in the inspection area R2. The third inspection is to check whether the front end 14e of the crack 14c extending from the modified region 12b to the front surface 21a side exists in the inspection area R2. The fourth inspection is to set the region extending from the reference position P toward the back surface 21b but not reaching the back surface 21b as the inspection region R3, and to inspect whether the tip position of the crack 14d extending from the modified region 12b toward the back surface 21b is located in the inspection region R3.

[0083] Before forming the two rows of modified regions 12a and 12b, the inspection region R1, the inspection region R2, and the inspection region R3 can be set according to the positions of the two light collecting points C1 and C2 relative to the semiconductor substrate 21. When the crack 14 across the two rows of modified regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21, the front end position of the crack 14 extending from the modified region 12b to the back surface 21b is stable, so the reference position P and the inspection region R3 can be set according to the test processing results. In addition, the camera unit 4 is as follows Fig.13 and Fig.14 As shown, the two modified regions 12a and 12b can be photographed separately, so after forming two rows of modified regions 12a and 12b, the inspection region R1, the inspection region R2 and the inspection region R3 can be set separately according to the respective positions of the two modified regions 12a and 12b.

[0084] [Laser processing method and semiconductor device manufacturing method]

[0085] Reference Fig.15 The semiconductor device manufacturing method of the present embodiment is described below. The semiconductor device manufacturing method of the present embodiment includes a laser processing method performed in the laser processing apparatus 1 .

[0086] First, a wafer 20 is prepared and placed on the mounting table 2 of the laser processing device 1. Next, the laser processing device 1 irradiates the wafer 20 with laser light L from the back side 21b of the semiconductor substrate 21 along a plurality of lines 15, thereby forming two rows of modified regions 12a and 12b inside the semiconductor substrate 21 along the plurality of lines 15 (S01, first step). In this step, the laser processing device 1 irradiates the wafer 20 with laser light L from the back side 21b of the semiconductor substrate 21 along the plurality of lines 15, respectively, under the condition that the cracks 14 across the two rows of modified regions 12a and 12b reach the front side 21a of the semiconductor substrate 21.

[0087] Next, the laser processing device 1 inspects the front end position of the crack 14d extending from the modified region 12b to the back side 21b in the inspection region R3 between the modified region 12b and the back side 21b (S02, second step). In this step, the laser processing device 1 focuses F from the back side 21b in the inspection region R3 and detects the light I1 propagating from the front side 21a to the back side 21b in the semiconductor substrate 21, thereby inspecting whether the front end position of the crack 14d is located in the inspection region R3. In this way, in this embodiment, the laser processing device 1 performs the fourth inspection.

[0088] More specifically, the objective lens 43 of the camera unit 4 is aligned with the focus F from the back side 21b in the inspection area R3, and the light detection unit 44 of the camera unit 4 detects the light I1 propagating from the front side 21a to the back side 21b in the semiconductor substrate 21. At this time, the camera unit 4 is moved along the Z direction by the driving unit 7, and the focus F is relatively moved along the Z direction in the inspection area R3. Thus, the light detection unit 44 obtains image data at various locations in the Z direction. In addition, the control unit 8 checks whether the front end position of the crack 14d is located in the inspection area R3 based on the signal output from the light detection unit 44 (i.e., the image data at various locations in the Z direction). In this way, in the present embodiment, the control unit 8 is used as an inspection unit, and the mounting table 2, the camera unit 4 and the control unit 8 are used as the inspection device 10.

[0089] Next, the control unit 8 evaluates the processing result of step S01 based on the inspection result of step S02 (S03, step 3). In this step, when the front end position of the crack 14d is located in the inspection region R3, the front end position of the crack 14d is located on the back surface 21b side relative to the reference position P, and the control unit 8 evaluates that the crack 14 across the two rows of modified regions 12a and 12b has reached the front surface 21a of the semiconductor substrate 21. On the other hand, when the front end position of the crack 14d is not located in the inspection region R3, it is considered that the front end position of the crack 14d is located on the front surface 21a side relative to the reference position P, and the control unit 8 evaluates that the crack 14 across the two rows of modified regions 12a and 12b has not reached the front surface 21a of the semiconductor substrate 21.

[0090] Next, when the crack 14 that is evaluated to be across the two rows of reformed regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21, the control unit 8 performs a pass process (S04). In this step, the control unit 8 performs the pass process by displaying the pass on the display of the laser processing device 1, displaying the image data on the display, recording the pass on the storage unit of the laser processing device 1 (storing as a log), storing the image data in the storage unit, etc. In this way, the display of the laser processing device 1 functions as a notification unit that notifies the operator of the pass.

[0091] On the other hand, when it is evaluated that the crack 14 across the two rows of reformed regions 12a and 12b has not reached the front surface 21a of the semiconductor substrate 21, the control unit 8 implements a failure process (S05). In this step, the control unit 8 causes the lighting of the failure indication of the lamp of the laser processing device 1, the display of the failure indication of the laser processing device 1, the recording of the failure indication of the storage unit of the laser processing device 1 (storage as a log), etc. as a failure process. In this way, at least one of the lamp and the display of the laser processing device 1 is used as a notification unit to notify the operator of the failure indication.

[0092] The above steps S01 to S05 are the laser processing method implemented in the laser processing device 1. In addition, the timing of implementing the fourth inspection is not limited to after forming two rows of modified regions 12a and 12b along all the lines 15 in the semiconductor substrate 21. The timing of implementing the fourth inspection may be after the modified regions 12a and 12b are formed along the multiple lines 15 extending in one direction, and before the modified regions 12a and 12b are further formed along the multiple lines 15 extending in one direction, when the alignment of the irradiation position of the laser L relative to the lines 15 extending in one direction is implemented. Alternatively, the timing of implementing the fourth inspection may be the timing of switching from the formation of the modified regions 12a and 12b along the multiple lines 15 extending in one direction to the formation of the modified regions 12a and 12b along the multiple lines 15 extending in another direction. In addition, the implementation position of the fourth inspection may be at least one of the multiple lines 15 set in a grid shape. However, when the modified regions 12a and 12b are formed along multiple lines 15 extending in one direction, the fourth inspection is preferably performed at locations other than intersections of the lines 15 extending in another direction (intersections of the lines 15 extending in another direction and each of the multiple lines 15 extending in one direction). This is because the state of the crack 14 is likely to become unstable at the intersections of the lines 15 extending in another direction.

[0093] When the qualified processing of step S04 is implemented (that is, in step S03, when the crack 14 evaluated as spanning two rows of modified regions 12a, 12b reaches the front side 21a of the semiconductor substrate 21), the back side 21b of the semiconductor substrate 21 is ground by a grinding device so that the crack 14 spanning two rows of modified regions 12a, 12b is exposed on the back side 21b, and the chip 20 is cut into multiple semiconductor devices along multiple lines 15 (S06, step 4).

[0094] The above steps S01 to S06 are a semiconductor device manufacturing method including a laser processing method implemented in the laser processing apparatus 1. In addition, when the unqualified processing of step S05 is implemented (that is, in step S03, when it is evaluated that the crack 14 spanning the two rows of modified regions 12a and 12b does not reach the front surface 21a of the semiconductor substrate 21), the inspection and adjustment of the laser processing apparatus 1, the laser processing (recovery processing) of the wafer 20, etc. are implemented.

[0095] Here, the grinding and cutting of the wafer 20 in step S06 will be described in more detail. Fig.16 As shown, the back side 21b of the semiconductor substrate 21 is ground (milled) by the grinding device 200 to thin the semiconductor substrate 21 and expose the cracks 14 on the back side 21b, and the wafer 20 is cut into a plurality of semiconductor devices 20a along a plurality of lines 15. In this step, the grinding device 200 grinds the back side 21b of the semiconductor substrate 21 to the fourth reference position P for inspection.

[0096] As described above, when the crack 14 spanning the two rows of modified regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21, the front end position of the crack 14 extending from the modified region 12b to the back surface 21b is located on the back surface 21b side relative to the reference position P. Therefore, by grinding the back surface 21b of the semiconductor substrate 21 to the reference position P, the crack 14 spanning the two rows of modified regions 12a and 12b can be exposed to the back surface 21b. In other words, with the grinding end predetermined position as the reference position P, and under the condition that the crack 14 spanning the two rows of modified regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21 and the reference position P, the laser L is irradiated to the wafer 20 from the back surface 21b side of the semiconductor substrate 21 along the plurality of lines 15 respectively.

[0097] Then, if Fig.17As shown, the expansion device 300 expands the expansion tape 201 attached to the back surface 21b of the semiconductor substrate 21, thereby separating the plurality of semiconductor devices 20a from each other. The expansion tape 201 is, for example, a DAF (Die Attach Film) composed of a base material 201a and an adhesive layer 201b. In this case, by expanding the expansion tape 201, the adhesive layer 201b disposed between the back surface 21b of the semiconductor substrate 21 and the base material 201a is cut for each semiconductor device 20a. The cut adhesive layer 201b is picked up together with the semiconductor device 20a.

[0098] [Function and effect]

[0099] In the above-mentioned laser processing method, the light I1 propagating from the front side 21a to the back side 21b of the semiconductor substrate 21 is detected by focusing F in the inspection area R3 between the reformed area 12b and the back side 21b of the semiconductor substrate 21. By detecting the light I1 in this way, the front end position of the crack 14d extending from the reformed area 12b to the back side 21b can be confirmed in the inspection area R3. Moreover, when the front end position of the crack 14d is located on the front side 21a relative to the reference position P, it is estimated that the crack 14 across the two rows of reformed areas 12a and 12b has not reached the front side 21a of the semiconductor substrate 21. Therefore, according to the above-mentioned laser processing method, it is possible to confirm whether the crack 14 across the two rows of reformed areas 12a and 12b has reached the front side 21a of the semiconductor substrate 21.

[0100] Furthermore, in the above-mentioned laser processing method, when the front end position of the crack 14d is not located on the front surface 21a side relative to the reference position P, it is evaluated that the crack 14 spanning the two rows of reformed regions 12a and 12b has reached the front surface 21a of the semiconductor substrate 21, and when the front end position of the crack 14d is located on the front surface 21a side relative to the reference position P, it is evaluated that the crack 14 spanning the two rows of reformed regions 12a and 12b has not reached the front surface 21a of the semiconductor substrate 21. Thus, the implementation of the subsequent steps can be determined based on the evaluation results.

[0101] Furthermore, in the above-mentioned laser processing method, the region extending from the reference position P toward the back surface 21b side and not reaching the back surface 21b is set as the inspection region R3, and when the front end position of the crack 14d is located in the inspection region R3, it is evaluated that the crack 14 spanning the two rows of modified regions 12a and 12b has reached the front surface 21a of the semiconductor substrate 21, and when the front end position of the crack 14d is not located in the inspection region R3, it is evaluated that the crack 14 spanning the two rows of modified regions 12a and 12b has not reached the front surface 21a of the semiconductor substrate 21. The case where the front end position of the crack 14d is such that the crack 14 spanning the two rows of modified regions 12a and 12b reaches the front surface 21a of the semiconductor substrate 21 is more stable than the case where the crack 14 spanning the two rows of modified regions 12a and 12b has not reached the front surface 21a of the semiconductor substrate 21. Therefore, by setting the region extending from the reference position P toward the back surface 21b but not reaching the back surface 21b as the inspection region R3, the inspection of the crack 14 spanning the two rows of reformed regions 12a and 12b can be efficiently performed.

[0102] In the above laser processing method, two rows of reformed regions 12a and 12b are formed as the multiple rows of reformed regions 12. This allows the formation of multiple rows of reformed regions 12 and the inspection of cracks 14 across the multiple rows of reformed regions 12 to be performed efficiently.

[0103] In addition, according to the above-mentioned semiconductor device manufacturing method, when it is evaluated that the crack 14 spanning two rows of modified regions 12a and 12b has not reached the front side 21a of the semiconductor substrate 21, grinding of the back side 21b of the semiconductor substrate 21 is not performed, thereby preventing the situation in which the chip 20 cannot be reliably cut along multiple lines 15 respectively after the grinding step.

[0104] Furthermore, in the above-described semiconductor device manufacturing method, the back surface 21 b of the semiconductor substrate 21 is ground to the reference position P. Thus, the wafer 20 can be reliably cut along each of the multiple lines 15 .

[0105] Furthermore, the inspection device 10 detects the light I1 propagating from the front side 21a to the back side 21b of the semiconductor substrate 21 by focusing F in the inspection region R3 between the modified region 12b and the back side 21b of the semiconductor substrate 21. By detecting the light I1 in this way, the front end position of the crack 14d in the inspection region R3 can be confirmed.

[0106] In the inspection device 10, the numerical aperture of the objective lens 43 is set to be 0.45 or more. This allows the tip position of the crack 14d to be more reliably confirmed in the inspection region R3.

[0107] Furthermore, in the inspection device 10, the objective lens 43 has the correction ring 43a. This makes it possible to more reliably check the tip position of the crack 14d in the inspection region R3.

[0108] [Modifications]

[0109] The present application is not limited to the above-mentioned embodiments. Fig.15 In the inspection step of step S02 shown in the figure, the control unit 8 may perform at least one of the first inspection, the second inspection, and the third inspection in addition to the fourth inspection. Furthermore, in the fourth inspection, for example, the entire area between the modified region 12b and the back surface 21b may be used as the inspection area R3 to inspect whether the front end position of the crack 14d is located on the back surface 21b side relative to the reference position P.

[0110] In the above-described embodiment, the laser processing device 1 forms two rows of modified regions 12a and 12b inside the semiconductor substrate 21 along the plurality of lines 15, respectively. However, the laser processing device 1 may form three or more rows of modified regions 12 inside the semiconductor substrate 21 along the plurality of lines 15, respectively. The number of rows and positions of the modified regions 12 formed on one line 15 may be appropriately set in consideration of the thickness of the semiconductor substrate 21 of the wafer 20, the thickness of the semiconductor substrate 21 of the semiconductor device 20a, and the like. In addition, the plurality of rows of modified regions 12 may be formed by relatively moving the focal point C of the laser light L for a plurality of times on one line 15.

[0111] In addition, the Fig.15 In the grinding and cutting step of step S06 shown in the figure, the grinding device 200 may also grind the back surface 21b of the semiconductor substrate 21 beyond the reference position P. The grinding end predetermined position can be appropriately set according to whether the modified region 12 is left on the side surface (cut surface) of the semiconductor device 20a. In addition, when the semiconductor device 20a is, for example, a DRAM (Dynamic Random Access Memory), the modified region 12 may also be left on the side surface of the semiconductor device 20a.

[0112] In addition, if Fig.18 As shown, the inspection device 10 may also be configured as a separate entity from the laser processing device 1. Fig.18 The inspection device 10 shown includes a stage 101, a drive unit 102, and a control unit 103 in addition to the imaging unit 4. The stage 101 is configured similarly to the above-mentioned stage 2, and supports a wafer 20 having a plurality of rows of modified regions 12. The drive unit 102 supports the imaging unit 4 and moves the imaging unit 4 in the Z direction. The control unit 103 is configured similarly to the above-mentioned control unit 8, and serves as an inspection unit. Fig.18 In the laser processing system shown, a wafer 20 is transported between a laser processing apparatus 1 and a detection apparatus 10 via a transport device such as a robot arm.

[0113] In addition, the irradiation conditions of the laser L when the wafer 20 is irradiated with the laser L from the back side 21b of the semiconductor substrate 21 along the plurality of lines 15 are not limited to the above-mentioned conditions. For example, the irradiation conditions of the laser L may be conditions such that the cracks 14 across the plurality of rows of modified regions 12 (e.g., two rows of modified regions 12a, 12b) reach the interface between the semiconductor substrate 21 and the functional element layer 22 as described above. Alternatively, the irradiation conditions of the laser L may be conditions such that the cracks 14 across the plurality of rows of modified regions 12 reach the front side of the functional element layer 22 opposite to the semiconductor substrate 21. Alternatively, the irradiation conditions of the laser L may be conditions such that the cracks 14 across the plurality of rows of modified regions 12 reach the vicinity of the front side 21a in the semiconductor substrate 21. In this way, the irradiation conditions of the laser L may be conditions such that the cracks 14 across the plurality of rows of modified regions 12 can be formed. In either case, it is possible to confirm whether the cracks 14 across the plurality of rows of modified regions 12 fully extend to the front side 21a of the semiconductor substrate 21.

[0114] In addition, each structure in the above-mentioned embodiment is not limited to the above-mentioned material and shape, and various materials and shapes can be applied. In addition, each structure in the above-mentioned one embodiment or modification example can be arbitrarily applied to each structure in other embodiments or modification examples.

[0115] Explanation of symbols

[0116] 2… mounting table, 8… control unit (inspection unit), 10… inspection device, 12, 12a, 12b… modified area, 14, 14d… crack, 14e… front end, 15… line, 20… wafer, 20a… semiconductor device, 21… semiconductor substrate, 21a… front side, 21b… back side, 22… functional element layer, 22a… functional element, 41… light source, 43… objective lens, 43a… correction ring, 44… light detection unit, F… focus, I1… light, L… laser, P… reference position, R3… inspection area.

Claims

1. A laser processing method, characterized in that: include: Step 1, preparing a wafer including a semiconductor substrate having a front side and a back side and a functional element layer formed on the front side, irradiating the wafer with laser light from the back side along a plurality of lines respectively, so as to form modified regions inside the semiconductor substrate along the plurality of lines respectively; and In the second step, in the inspection area between the modified area and the back surface, the front end position of the crack extending from the modified area to the back surface side is inspected, In the second step, the focus is focused from the back side to the inspection area and the focus is relatively moved along the thickness direction of the chip within the inspection area, and the light propagating from the front side to the back side in the semiconductor substrate is detected, thereby obtaining image data at each position in the thickness direction, and based on the image data, checking whether the front end position is located in the inspection area.

2. The laser processing method according to claim 1, characterized in that: In the first step, the wafer is irradiated with the laser light from the back side along the plurality of lines under the condition that the crack reaches the front side.

3. The laser processing method according to claim 2, characterized in that: The method further includes a third step of evaluating the processing result of the first step based on the inspection result of the second step, In the third step, when the front end position is located on the back side relative to the reference position between the modified region and the back side, it is evaluated that the crack has reached the front side, and when the front end position is located on the front side relative to the reference position, it is evaluated that the crack has not reached the front side.

4. The laser processing method according to claim 3, characterized in that: The inspection area is an area extending from the reference position toward the back side but not reaching the back side. In the third step, when the tip position is located in the inspection region, it is evaluated that the crack has reached the front surface, and when the tip position is not located in the inspection region, it is evaluated that the crack has not reached the front surface.

5. A method for manufacturing a semiconductor device, characterized in that: include: The laser processing method according to claim 3 or 4 comprises the first step, the second step and the third step; as well as In a fourth step, when it is evaluated in the third step that the crack has reached the front surface, the wafer is cut into a plurality of semiconductor devices along the plurality of lines.

6. An inspection device, characterized in that: include: A platform for supporting a wafer, wherein the wafer includes a semiconductor substrate having a front side and a back side and a functional element layer formed on the front side, and wherein modified regions are formed along a plurality of lines inside the semiconductor substrate; a light source that outputs light that is transmissive to the semiconductor substrate; an objective lens for transmitting the light output from the light source and propagating in the semiconductor substrate; a light detecting unit for detecting the light transmitted from the objective lens; and an inspection unit that inspects the tip position of a crack extending from the modified region toward the back side in an inspection region between the modified region and the back side based on the signal output from the light detection unit, The objective lens is focused into the inspection area from the back side, The light detection unit detects the light propagating from the front side to the back side in the semiconductor substrate. The inspection unit focuses the objective lens from the back side to the inspection area and relatively moves the focus along the thickness direction of the chip within the inspection area, while the light detection unit detects the light propagating from the front side to the back side in the semiconductor substrate, thereby obtaining image data at each position in the thickness direction, and based on the image data, checks whether the front end position is located in the inspection area.

7. The inspection device according to claim 6, characterized in that: The numerical aperture of the objective lens is greater than 0.

45.

8. The inspection device according to claim 6 or 7, characterized in that: The objective lens has a correction collar.

Images