TW202030781A - Imaging device, laser processing device, and imaging method - Google Patents

Abstract

This imaging device, for imaging a reformed region formed in an object by irradiation with a laser and/or a crack extending from the reformed region, is provided with a first imaging unit which images the object with light transmitted through the object, and a first control unit which controls the first imaging unit. The object contains multiple functional elements delimited by a first line and a second line intersecting the first line seen from a direction crossing the plane of incidence of the aforementioned laser. After the reformed region has been formed along the first line and the second line, the first control unit performs first imaging processing which controls the first imaging unit so as to image the reformed region, and/or the region containing the aforementioned crack extending from the reformed region, which is a region on the side of the functional element corresponding to the first line seen from the aforementioned direction.

Description

Imaging device, laser processing device, and imaging method

One aspect of this disclosure relates to an imaging device, a laser processing device, and an imaging method.

There is known a laser processing apparatus for cutting a wafer having a semiconductor substrate and a functional element layer formed on the surface of the semiconductor substrate along a plurality of lines, respectively, and irradiating the wafer with a laser from the back side of the semiconductor substrate. Light is emitted, thereby forming a plurality of rows of modified regions inside the semiconductor substrate along a plurality of lines, respectively. The laser processing apparatus described in Patent Document 1 is equipped with an infrared camera and can observe the modified region formed inside the semiconductor substrate, the processing damage that forms the functional element layer, and the like from the back side of the semiconductor substrate. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2017-64746 A

[Technical Problem to be Solved by Invention]

Like the laser processing apparatus described in the aforementioned Patent Document 1, there is a demand for nondestructively confirming the modified area formed in the wafer. In contrast, in the laser processing apparatus described in Patent Document 1, the imaging position of the wafer by the infrared camera is arranged on a straight line on the downstream side of the wafer moving direction with respect to the processing position of the wafer of the processing optical system.

Therefore, the infrared camera photographs the wafer on the same cutting line as the processing position of the wafer of the processing optical system, thereby enabling instant confirmation and measurement of the formation position or processing damage of the modified region formed inside the wafer Wait. However, it takes a certain amount of time to confirm and measure the modified area using infrared cameras. Therefore, if the laser processing device described in Patent Document 1 intends to simultaneously form the modified region and confirm the modified region, it will limit the speed of forming the modified region, which may reduce the processing efficiency.

Therefore, one aspect of the present disclosure aims to provide an imaging device, a laser processing device, and an imaging method that can suppress a decrease in processing efficiency and can perform confirmation in a non-destructive manner. [Technical solution to solve the problem]

One aspect of the present disclosure is: an imaging device for imaging a modified area formed by irradiating a laser light on an object and/or a crack extending from the modified area; the feature is that it has: a first imaging device The unit captures the object by the light penetrating the object; and the first control unit controls the first imaging unit; the object is viewed from the direction crossing the incident surface of the laser light, including by the first line and A plurality of functional elements defined by a second line crossing the first line, the first control unit, after forming modified areas along the first and second lines, executes the first imaging process, the first imaging process The first imaging unit is controlled in such a way that the region corresponding to the side of the first line of the functional element viewed from this direction is imaged and is a modified region and/or a region including a crack extending from the modified region.

In this device, the first control unit executes the first imaging process, and the first imaging process is to capture the modified area of the object by light penetrating the object and/or include the area extending from the modified area The cracked area. Therefore, without destroying the object, it is possible to obtain images of modified regions and the like (modified regions and/or cracks extending from the modified regions (hereinafter the same)) and can be confirmed. In particular, in this device, the first control unit executes the aforementioned first imaging process after forming modified regions on the object along the first line and the second line. Therefore, without affecting the speed at which the modified region is formed, the modified region can be confirmed. That is, according to this device, it is possible to suppress a decrease in processing efficiency and to perform confirmation in a non-destructive manner. In addition, in this device, the area captured by the first imaging process is the side of the functional element constituting the object. In terms of the side of the functional element, compared to the corner of the functional element that intersects the modified area formed along the first line and the modified area formed along the second line, it has the quality of the modified area Higher tendency. Therefore, according to this device, the modified region and the like can be confirmed with high accuracy.

The imaging device of one form of the present disclosure may also be: the first control unit executes a second imaging process after forming modified regions along the first line and the second line. The second imaging process is The first imaging unit is controlled in such a manner that the area corresponding to the side of the second line of the functional element viewed from this direction is a modified area and/or an area including a crack extending from the modified area. At this time, it is possible to suppress a decrease in processing efficiency, and it is possible to non-destructively confirm the modified regions and the like formed along lines that cross each other.

A laser processing device of one form of the present disclosure is provided with: the aforementioned imaging device; a laser irradiation unit for irradiating laser light on an object; and a drive unit, which is equipped with a laser irradiation unit to irradiate the laser The unit is driven in a direction crossing the incident surface of the laser light of the object; the first camera unit is installed in the drive unit together with the laser irradiation unit.

This device is equipped with the aforementioned imaging device. Therefore, according to this device, it is possible to suppress reduction in processing efficiency and to perform confirmation in a non-destructive manner. In addition, this device includes a drive unit that drives the laser irradiation unit in a direction (incident direction) that crosses the incident surface of the laser light of the object. In addition, the first imaging unit is attached to the drive unit together with the laser irradiation unit. Therefore, in the formation of modified regions by irradiating laser light and the first imaging process, the position information of the incident direction can be easily shared.

The laser processing device of one form of the present disclosure may also be provided with: a second imaging unit that images the object by light penetrating the object; and a second control unit that controls the laser irradiation unit and the second Image pickup unit; The first image pickup unit has: a first lens that allows light passing through an object to pass; and a first light detection unit that detects the light that has passed through the first lens; a second image pickup unit It has: a second lens that allows light that has passed through the object to pass through; and a second light detection unit that detects the light that has passed through the second lens; and a second control unit that performs alignment processing, the alignment processing , The laser irradiation unit and the second imaging unit are controlled in such a way that the irradiation position of the laser light is aligned based on the detection result of the second light detection unit. In this way, in addition to the first imaging unit for imaging the modified area and the like, the second imaging unit for aligning the irradiation position of the laser light is additionally used, so that each appropriate optical system can be used.

The laser processing device of one form of the present disclosure may also be that the numerical aperture of the first lens is larger than the numerical aperture of the second lens. At this time, the alignment can be performed more reliably by observation of a relatively small numerical aperture, and the area can be modified by imaging with a relatively large numerical aperture.

One aspect of the present disclosure is: an imaging method for imaging a modified area formed by irradiating a laser light on an object and/or a crack extending from the modified area; it is characterized by: having: a first imaging The step is to image the object; the object, viewed from the direction crossing the incident surface of the laser light, includes a plurality of functional elements defined by the first line and the second line that crosses the first line, and then the first image is captured In the step, after the modified area is formed along the first and second lines, the area corresponding to the side of the first line of the functional element viewed from this direction is imaged and is the modified area and/or includes the modified area. A cracked area extending from the qualitative area.

In this method, the modified area of the object and/or the area including the crack extending from the modified area is captured by light penetrating the object. Therefore, it is possible to confirm the modified area and the like without destroying the object. In particular, in this method, the aforementioned imaging is performed after forming modified regions along the first line and the second line. Therefore, without affecting the speed at which the modified region is formed, the modified region can be confirmed. That is, according to this method, it is possible to suppress a decrease in processing efficiency and to perform confirmation in a non-destructive manner. In addition, in this method, the imaged area is the side portion of the functional element constituting the object. In terms of the side portion of the functional element, there are modified areas, etc., compared to the corner portions of the functional element that intersect the modified areas formed along the second line, etc., along the first line, etc. The tendency of higher quality. Therefore, according to this method, the modified region and the like can be confirmed with high accuracy.

The imaging method of one form of the present disclosure may also include: a second imaging step, which is an imaging object; in the second imaging step, after forming modified regions along the first and second lines, The region corresponding to the side of the second line of the functional element viewed from this direction is a modified region and/or a region including a crack extending from the modified region. At this time, it is possible to suppress a decrease in processing efficiency, and it is possible to non-destructively confirm the modified regions and the like formed along lines that cross each other. [Effects of Invention]

According to one aspect of the present disclosure, it is possible to provide an imaging device, a laser processing device, and an imaging method capable of suppressing a decrease in processing efficiency and enabling confirmation in a non-destructive manner

Hereinafter, the embodiment will be described in detail with reference to the drawings. In addition, in each figure, the same element or the equivalent element may be given the same reference numeral, and repeated descriptions may be omitted. Moreover, in the drawing, there is a rectangular coordinate system defined by the X axis, Y axis and Z axis.

As shown in FIG. 1, the laser processing device 1 includes a stage 2, a laser irradiation unit 3, a plurality of imaging units 4, 5, and 6, a drive unit 7, and a control unit 8. The laser processing device 1 is a device that irradiates a target 11 with laser light L to thereby form a modified region 12 on the target 11.

The stage 2 supports the object 11 by, for example, a film attached to the object 11 by suction. The stage 2 can move along the X direction and the Y direction, and can rotate about an axis parallel to the Z direction as a centerline. In addition, 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.

The laser irradiation unit 3 condenses the laser light L having penetrability to the object 11 to irradiate the object 11. When the laser light L is condensed to the inside of the object 11 supported by the stage 2, the laser light L is absorbed in the part corresponding to the condensing point C of the laser light L, and a modified area is formed inside the object 11 12.

The modified region 12 is a region where the density, refractive index, mechanical strength, or other physical properties are different from the surrounding non-modified regions. As the modified region 12, there are, for example, a molten processed region, a crack region, a dielectric 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 and the opposite side of the laser light L. The characteristics of the modified region 12 as described above are used for the cutting object 11.

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

The imaging unit (first imaging unit) 4 is controlled by the control unit (first control unit) 8 to pick up the object 11 supported by the stage 2 by light that penetrates the object 11. More specifically, the imaging unit 4 captures the modified region 12 formed on the object 11 and the tip of the crack extending from the modified region 12. In this embodiment, the imaging unit 4 and the control section 8 that controls the imaging unit 4 function as the imaging device 10.

The imaging unit (second imaging unit) 5 and the imaging unit 6 are controlled by the control unit (second control unit) 8 to image the object 11 supported by the stage 2 by light penetrating the object 11. The image obtained by imaging by the imaging units 5 and 6 is used as an example to align the irradiation position of the laser light L.

The driving unit 7 supports the laser irradiation unit 3 and a plurality of imaging units 4, 5, and 6. In other words, the laser irradiation unit 3 is mounted on the drive unit 7. In addition, the imaging units 4, 5, and 6 are mounted on the drive unit 7 together with the laser irradiation unit 3. The driving unit 7 moves the laser irradiation unit 3 and the plurality of imaging units 4, 5, and 6 along the Z direction. Here, the Z direction is a direction crossing the incident surface of the laser light L of the object 11 (for example, the rear surface 21b described later).

The control unit 8 controls the operations of the stage 2, the laser irradiation unit 3, the plurality of imaging units 4, 5, and 6 and the drive unit 7. The control unit 8 is constituted as a computer device including a processor, memory, storage, and communication device. In the control section 8, the processor executes the software (program) read by the memory, reads or writes data in the memory and the storage, and controls the communication performed by the communication device. [Constitution of Object]

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

The wafer 20 is cut along a plurality of lines 15 into individual functional elements 22a. The plurality of wires 15 pass between the respective plurality of functional elements 22a when viewed from the thickness direction of the wafer 20. More specifically, the plurality of lines 15 pass through the center of the ruled line region 23 (the center in the width direction) when viewed from the thickness direction of the wafer 20. The ruled line region 23 is tied to the functional element layer 22 and extends so as to pass between adjacent functional elements 22a. In this embodiment, the plurality of functional elements 22a are arranged in a matrix along the surface 21a, and the plurality of lines 15 are set in a lattice shape. In addition, although the line 15 is an imaginary line, it may be a line actually drawn.

The line 15 includes a plurality of first lines 15a and a plurality of second lines 15b crossing (orthogonal to) the first line 15a. Here, the first wires 15a are parallel to each other, and the second wires 15b are parallel to each other. Thereby, a pair of first wires 15a adjacent to each other and a pair of second wires 15b adjacent to each other define one functional element 22a in the shape of a rectangular parallelepiped. In other words, the wafer 20 (object 11), when viewed from the Z direction, includes a plurality of functional elements 22a defined by the first line 15a and the second line 15b. The intersection of the first line 15a and the second line 15b defines the corner of the functional element 22a, and the first line 15a and the second line 15b each define the side of the functional element 22a. [Configuration of Laser Irradiation Unit]

As shown in FIG. 4, the laser irradiation unit 3 has a light source 31, a spatial light modulator 32, and a condenser lens 33. The light source 31 outputs laser light L by a pulse oscillation method, for example. 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 reflective liquid crystal (LCOS: Liquid Crystal on Silicon) spatial light modulator (SLM: Spatial Light Modulator). The condenser lens 33 condenses the laser light L modulated by the spatial light modulator 32.

In this embodiment, the laser irradiation unit 3 irradiates the laser light L to the wafer 20 from the back surface 21b side of the semiconductor substrate 21 along a plurality of lines 15 respectively, thereby respectively along the plurality of lines 15 on the semiconductor substrate 21 Two rows of modified regions 12a, 12b are formed inside of The modified region (first modified region) 12a is the modified region closest to the surface 21a among 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 among the two rows of modified regions 12a, 12b, and is the modified region closest to the inner surface 21b.

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 condensing 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 such that, for example, the condensing point C2 is located on the rear side of the traveling direction relative to the condensing point C1 and on the incident side of the laser light L.

The laser irradiation unit 3, under the condition that the cracks 14 spanning the two rows of modified regions 12a, 12b reach the surface 21a of the semiconductor substrate 21, face the crystal from the back 21b side of the semiconductor substrate 21 along a plurality of lines 15 respectively. The circle 20 irradiates the laser light L. As an example, for a semiconductor substrate 21 that is a single crystal silicon substrate with a thickness of 775 μm, two condensing points C1 and C2 are focused on a position 54 μm and a position 128 μm from the surface 21a, respectively, along a plurality of lines 15 from The wafer 20 is irradiated with laser light L on the back surface 21b side of the semiconductor substrate 21. At this time, the wavelength of the laser light L is 1099 nm, the pulse width is 700 n seconds, and the repetition frequency is 120 kHz. In addition, the output of the laser light L at the focusing point C1 is 2.7W, the output of the laser light L at the focusing point C2 is 2.7W, and the relative movement speed of the two focusing points C1 and C2 with respect to the semiconductor substrate 21 is 800mm/sec. .

The formation of the two rows of modified regions 12a, 12b and the crack 14 is implemented in the following situation. That is, in the subsequent step, the semiconductor substrate 21 is thinned by grinding the back surface 21b of the semiconductor substrate 21, and the crack 14 is exposed on the back surface 21b, and the wafer 20 is cut along a plurality of lines 15 respectively. In the case of a plurality of semiconductor devices. [Configuration of Inspection Camera Unit]

As shown in FIG. 5, the imaging unit 4 includes a light source 41, a mirror 42, an objective lens (first lens) 43, and a light detection unit (first light detection unit) 44. The light source 41 outputs light I1 that is transparent 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 mirror 42 and passes through the objective lens 43 to irradiate the wafer 20 from the back surface 21b side of the semiconductor substrate 21. At this time, the stage 2 supports the wafer 20 in which two rows of modified regions 12a and 12b are formed as described above.

The objective lens 43 passes the light I1 reflected by the surface 21 a of the semiconductor substrate 21. That is, for the objective lens 43, the light I1 propagated (transmitted) through the semiconductor substrate 21 is passed through. The numerical aperture (NA) of the objective lens 43 is 0.45 or more. 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 by adjusting the distance between the plurality of lenses constituting the objective lens 43, for example. The light detection unit 44 detects the light I1 passing through the objective lens 43 and the mirror 42. The light detection unit 44 is constituted by, for example, an InGaAs camera, and detects light I1 in the near infrared region.

The imaging unit 4 is capable of imaging each of two rows of modified regions 12a, 12b, and respective tips of a 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 surface 21a side. The crack 14b is a crack extending from the modified region 12a to the inner side 21b. The crack 14c is a crack extending from the modified region 12b to the surface 21a side. The crack 14d is a crack extending from the modified region 12b to the inner side 21b. Although the control unit 8 causes the laser irradiation unit 3 to irradiate the laser light L (refer to FIG. 4) under the condition that the cracks 14 spanning the two rows of modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21, it is abnormal If the crack 14 does not reach the surface 21a, a plurality of cracks 14a, 14b, 14c, and 14d will be formed. [Configuration of imaging unit for alignment correction]

As shown in FIG. 6, the imaging unit 5 includes a light source 51, a mirror 52, a lens (second lens) 53, and a light detection unit (second light detection unit) 54. The light source 51 outputs light I2 that is transparent 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 be shared with the light source 41 of the imaging unit 4. The light I2 output from the light source 51 is reflected by the mirror 52, passes through the lens 53, and irradiates the wafer 20 from the back surface 21b side of the semiconductor substrate 21.

The lens 53 passes the light I2 reflected by the surface 21 a of the semiconductor substrate 21. That is, the lens 53 allows the light I2 passing through the semiconductor substrate 21 to pass. The numerical aperture of the lens 53 is 0.3 or less. 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 mirror 52. The light detection unit 55 is constituted by, for example, an InGaAs camera, and detects light I2 in the near infrared region.

The imaging unit 5 irradiates the light I2 to the wafer 20 from the back 21b side under the control of the control unit 8 (second control unit), and detects the light I2 returning from the surface 21a (functional element layer 22), thereby Imaging function element layer 22. In addition, the imaging unit 5 irradiates light to the wafer 20 from the side of the back surface 21b under the control of the control unit 8 and detects the light I2 returning from the formation positions of the modified regions 12a and 12b of the semiconductor substrate 21. This acquires an image of the area including the modified areas 12a and 12b. These images are used to align the irradiation position of the laser light L. The imaging unit 6 has the same configuration as the imaging unit 5, except that the magnification is lower than that of the lens 53 (for example, the imaging unit 5 is 6 times, and the imaging unit 6 is 1.5 times). Used for alignment. [The principle of imaging of the imaging unit for inspection]

Using the imaging unit 4 shown in FIG. 5, as shown in FIG. 7, for the cracks 14 spanning two rows of modified regions 12a and 12b to reach the semiconductor substrate 21 on the surface 21a, the focal point F (focus on the objective lens 43) is changed from The back surface 21b side moves toward the surface 21a side. In this case, if the focal point F is focused on the front end 14e of the crack 14 extending from the modified region 12b to the back 21b side from the back surface 21b side, the front end 14e can be confirmed (the image on the right in FIG. 7). However, even if the focal point F is focused on the crack 14 itself and the front end 14e of the crack 14 reaching the surface 21a from the side of the back 21b, it cannot be confirmed (the image on the left side of FIG. 7). In addition, if the focal point F is focused on the surface 21a of the semiconductor substrate 21 from the side of the back surface 21b, the functional element layer 22 can be confirmed.

And, using the imaging unit 4 shown in FIG. 5, as shown in FIG. 8, for the semiconductor substrate 21 where the crack 14 spanning two rows of modified regions 12a, 12b does not reach the surface 21a, the focal point F is moved from the back surface 21b side to the surface 21a side moves. In this case, if the focal point F is focused on the front end 14e of the crack 14 extending from the modified region 12a to the surface 21a side from the side of the back surface 21b, the front end 14e (the image on the left in FIG. 8) can be confirmed. However, if the focal point F is focused on the area opposite to the surface 21a and the back surface 21b from the back surface 21b side (that is, the area on the functional element layer 22 side relative to the surface 21a), the focal point F is The symmetrical virtual focal point Fv is located at the front end 14e, and the front end 14e can be confirmed (the image on the right side of FIG. 8). In addition, the virtual focal point Fv is a point symmetrical to the surface 21a and the focal point F in consideration of the refractive index of the semiconductor substrate 21.

The crack 14 cannot be confirmed as described above, and it is presumed that the width of the crack 14 is smaller than the wavelength of the light I1 as the illumination light. 9 and 10 are SEM (Scanning Electron Microscope) images of the modified region 12 and the crack 14 formed inside the semiconductor substrate 21 which is a silicon substrate. Fig. 9(b) is an enlarged image of the area A1 shown in Fig. 9(a), Fig. 10(a) is an enlarged image of the area A2 shown in Fig. 9(b), and Fig. 10(a) b) is an enlarged image of area A3 shown in (a) of Fig. 10. In this way, the width of the crack 14 is approximately 120 nm, which is smaller than the wavelength of the light I1 in the near infrared region (for example, 1.1 to 1.2 μm).

The imaging principles envisaged based on the above items are as follows. As shown in Fig. 11(a), if the focal point F is located in the air, the light I1 does not return, so a dark image (the image on the right side of Fig. 11(a)) is obtained. As shown in Figure 11(b), if the focal point F is located inside the semiconductor substrate 21, the light I1 reflected by the surface 21a will return, so a white image is obtained (Figure 11(b) on the right Like). As shown in Fig. 11(c), if the focal point F is focused on the modified region 12 from the side of the back surface 21b, a part of the light I1 reflected by the surface 21a will be absorbed, scattered, etc. due to the modified region 12. Therefore, an image (the image on the right side of (c) in FIG. 11) showing a dark modified area 12 in a white background is obtained.

As shown in (a) and (b) of Figure 12, if the focal point F is focused to the tip 14e of the crack 14 from the side of the back 21b, for example, due to optical specificity (stress concentration, distortion, The discontinuity of atomic density, etc.) causes the light to be confined near the front end 14e, thereby causing a part of the light I1 reflected by the surface 21a to be scattered, reflected, interfered, absorbed, etc., so that it will be displayed in a clear background An image of the pitch-black front end 14e (the image on the right side of (a) and (b) in Fig. 12) appears. As shown in Fig. 12(c), if the focal point F is focused from the back side 21b to a part other than the vicinity of the tip 14e of the crack 14, at least a part of the light I1 reflected by the surface 21a will return, so it will be white. Image (the image on the right side of (c) in Figure 12). [Inspection principle of imaging unit for inspection]

The control unit 8 causes the laser irradiation unit 3 to irradiate the laser light L under the condition that the cracks 14 across the modified regions 12a, 12b of the two rows reach the surface 21a of the semiconductor substrate 21, and as expected, the cracks 14 across the two rows When the crack 14 of the modified regions 12a and 12b reaches the surface 21a, the state of the tip 14e of the crack 14 will be as follows. That is, as shown in FIG. 13, in the area between the modified region 12a and the surface 21a, and the region between the modified region 12a and the modified region 12b, the tip 14e of the crack 14 does not appear. The position extending from the modified region 12b to the front end 14e of the crack 14 on the back side 21b side (hereinafter simply referred to as the "front end position") is on the back side 21b side with respect to the reference position P between the modified region 12b and the back side 21b .

On the other hand, the control unit 8 causes the laser irradiation unit 3 to irradiate the laser light L under the condition that the cracks 14 spanning the two rows of modified regions 12a, 12b reach the surface 21a of the semiconductor substrate 21. If the defect causes the crack 14 that straddles the modified regions 12a and 12b of the two rows and does not reach the surface 21a, the state of the tip 14e of the crack 14 will be as follows. That is, as shown in FIG. 14, in the region between the modified region 12a and the surface 21a, the tip 14e of the crack 14a extending from the modified region 12a to the surface 21a side appears. In the area between the modified region 12a and the modified region 12b, there will be a front end 14e of the crack 14b extending from the modified region 12a to the inner side 21b, and a crack 14c extending from the modified region 12b to the surface 21a side The front end 14e. The tip position of the crack 14 extending from the modified region 12b to the side of the back surface 21b is located on the surface 21a relative to the reference position P between the modified region 12b and the back surface 21b.

Based on the above matters, if the control unit 8 performs at least one of the next inspections of the first inspection, the second inspection, the third inspection, and the fourth inspection, it is possible to evaluate the tortoises that straddle the modified areas 12a and 12b Whether the crack 14 reaches the surface 21 a of the semiconductor substrate 21. In the first inspection, the area between the modified area 12a and the surface 21a is used as the inspection area R1, and it is determined whether the inspection area R1 has the tip 14e of the crack 14a extending from the modified area 12a to the surface 21a side. . In the second inspection, the area between the modified region 12a and the modified region 12b is used as the inspection region R2, and it is determined whether there is a tip 14e of the crack 14b extending from the modified region 12a to the back side 21b in the inspection region R2 Inspection. The third inspection is an inspection to determine whether there is a tip 14e of the crack 14c extending from the modified area 12b to the surface 21a side in the inspection area R2. In the fourth inspection, an area extending from the reference position P to the back 21b side and not reaching the back 21b is used as the inspection area R3, and it is judged whether the tip of the crack 14 extending from the modified area 12b to the back 21b side is located in the inspection area R3 inspection.

The inspection region R1, the inspection region R2, and the inspection region R3 can be set according to the positions where the two condensing points C1 and C2 are focused on the semiconductor substrate 21 before the two rows of modified regions 12a and 12b are formed, respectively. When the crack 14 straddling the modified regions 12a and 12b of the two rows reaches the surface 21a of the semiconductor substrate 21, the tip position of the crack 14 extending from the modified region 12b to the back 21b side is stable, so the reference position P And the inspection area R3 can be set according to the results of the measurement and processing. In addition, the imaging unit 4, as shown in FIGS. 13 and 14, can respectively image two modified regions 12a, 12b, so after forming two rows of modified regions 12a, 12b, the two modified regions 12a, 12b In the positions of the areas 12a and 12b, an inspection area R1, an inspection area R2, and an inspection area R3 are set. [Laser processing method and semiconductor device manufacturing method]

The semiconductor device manufacturing method of this embodiment will be described with reference to FIG. 15. In addition, the semiconductor device manufacturing method of the present embodiment includes the laser processing method performed by the laser processing device 1.

First, the wafer 20 is prepared and placed on the stage 2 of the laser processing apparatus 1. Next, the laser processing device 1 irradiates the wafer 20 with laser light L from the back surface 21b side of the semiconductor substrate 21 along a plurality of lines 15 respectively, thereby forming 2 in the semiconductor substrate 21 along the plurality of lines 15 respectively. The modified regions 12a and 12b are listed (S01, step 1). In this step, the laser processing device 1 is configured to allow the cracks 14 across the two rows of modified regions 12a and 12b to reach the surface 21a of the semiconductor substrate 21, respectively along a plurality of lines 15 from the semiconductor substrate 21 The wafer 20 is irradiated with laser light L on the back side 21b side.

Next, the laser processing device 1 checks the area between the modified region 12a and the modified region 12b as the inspection region R2 for the presence of the tip 14e of the crack 14b extending from the modified region 12a to the back 21b side (S02 , Step 2). In this step, the laser processing device 1 focuses the focal point F into the inspection area R2 from the back surface 21b side, and detects the light I1 propagating (penetrating) the semiconductor substrate 21 from the surface 21a side to the back surface 21b side, by In this inspection, the front end 14e of the crack 14b is present in the inspection area R2. In this way, in this embodiment, the laser processing apparatus 1 performs the second inspection.

More specifically, the objective lens 43 of the imaging unit 4 focuses the focal point F into the inspection area R2 from the side of the back 21b, and the light detection section 44 of the imaging unit 4 detects that it is from the side 21a to the side 21b. The semiconductor substrate 21 propagates (transmits) light I1. At this time, the imaging unit 4 is moved in the Z direction by the drive unit 7 so that the focal point F is relatively moved in the Z direction in the inspection area R2. Thereby, the light detection unit 44 obtains image data of each part in the Z direction. Therefore, the control unit 8 checks whether there is a tip 14e of the crack 14b in the inspection area R2 based on the signal output from the light detection unit 44 (that is, the image data of each part in the Z direction).

Next, the control unit 8 evaluates the processing result of step S01 based on the inspection result of step S02 (S03, third step). In this step, when the tip 14e of the crack 14b does not exist in the inspection region R2, the control unit 8 evaluates that the crack 14 spanning the two rows of modified regions 12a, 12b reaches the surface 21a of the semiconductor substrate 21. On the other hand, when there is a tip 14e of the crack 14b in the inspection region R2, the control unit 8 evaluates that the crack 14 spanning the two rows of modified regions 12a and 12b has not reached the surface 21a of the semiconductor substrate 21.

Next, when it is evaluated that the crack 14 straddling the modified regions 12a and 12b of the two rows reaches the surface 21a of the semiconductor substrate 21, the control unit 8 performs a pass process (S04). In this step, as the pass processing, the control unit 8 causes the display of the laser processing device 1 to display the pass status, the display of image data on the display, and the memory unit of the laser processing device 1 The record of qualified memory (memory as a log), the memory of image data by the memory unit, etc. In this way, the display included in the laser processing apparatus 1 functions as a notification unit that notifies the operator of the qualified status.

On the other hand, when it is evaluated that the crack 14 that straddles the modified regions 12a and 12b of the two rows has not reached the surface 21a of the semiconductor substrate 21, the control unit 8 performs a failure process (S05). In this step, as the failure processing, the control unit 8 turns on the lamp of the laser processing device 1 to indicate the failure, and the display of the laser processing device 1 displays the failure status, The record of the failure situation (memory as a log) and the like are memorized by the memory unit included in the laser processing device 1. In this way, at least one of the lamp and the display included in the laser processing apparatus 1 functions as a notification unit that notifies the operator of the failure.

The above steps S01 to S05 are the laser processing method implemented by the laser processing device 1.

In the case of performing the pass processing of step S04 (that is, in step S03, it is evaluated that the crack 14 spanning two rows of modified regions 12a, 12b reaches the surface 21a of the semiconductor substrate 21), the semiconductor is ground by a grinding device The back surface 21b of the substrate 21 exposes the cracks 14 spanning two rows of modified regions 12a and 12b on the back surface 21b, and the wafer 20 is cut into a plurality of semiconductor devices along a plurality of lines 15 respectively (S06, the first 4 steps).

The above steps S01 to S06 are the semiconductor device manufacturing method including the laser processing method implemented by the laser processing device 1. In addition, in the case of performing the failure processing of step S05 (that is, in step S03, it is evaluated that the crack 14 spanning the two rows of modified regions 12a, 12b has not reached the surface 21a of the semiconductor substrate 21), the mine Inspection and adjustment of the laser processing device 1, laser processing (recovery processing), etc. on the wafer 20 again.

Here, the grinding and cutting of the wafer 20 in step S06 will be described in more detail. As shown in FIG. 16, the back surface 21b of the semiconductor substrate 21 is ground (polished) by the grinding device 200 to make the semiconductor substrate 21 thinner, and the cracks 14 are exposed on the back surface 21b, and the wafer 20 is separated along a plurality of lines 15 respectively. Cut into a plurality of semiconductor devices 20a. In this step, the grinding apparatus 200 grinds the back surface 21b of the semiconductor substrate 21 to the reference position P for the fourth inspection.

As described above, when the crack 14 that straddles the modified regions 12a and 12b of the two rows reaches the surface 21a of the semiconductor substrate 21, the front end of the crack 14 extending from the modified region 12b to the back 21b side is opposite to The reference position P is located on the side of the back 21b. Therefore, by grinding the back surface 21b of the semiconductor substrate 21 to the reference position P, it is possible to expose the cracks 14 spanning the two rows of modified regions 12a and 12b on the back surface 21b. In other words, the predetermined position for the grinding end is used as the reference position P, and the cracks 14 across the two rows of modified regions 12a and 12b reach the surface 21a of the semiconductor substrate 21 and the reference position P, respectively along the plurality of lines 15 The wafer 20 is irradiated with laser light L from the back surface 21b side of the semiconductor substrate 21.

Next, as shown in FIG. 17, 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 substrate 201a and an adhesive layer 201b. In this case, by the expansion of the expansion tape 201, the adhesive layer 201b arranged between the back surface 21b of the semiconductor substrate 21 and the base material 201a is cut along with the semiconductor device 20a. The cut adhesive layer 201b is picked up together with the semiconductor device 20a.

Here, as described above, when checking whether the tip 14e of the crack 14b exists in a predetermined area, imaging of the wafer 20 is performed. The imaging of the wafer 20 is performed by the imaging device 10 composed of the imaging unit 4 and the control unit 8. In the foregoing example, after forming two rows of modified regions 12a and 12b inside the semiconductor substrate 21 along all the lines 15 respectively, the wafer 20 is imaged with the implementation of the second inspection. Hereinafter, the laser processing method will be explained in detail, including the timing of imaging.

The laser processing method shown in Fig. 18 includes an imaging method. As shown in FIG. 18, here, first, the wafer 20 is placed on the stage 2 of the laser processing apparatus 1, and the processing start position is aligned (S11). In this step, for example, the imaging unit 5 images the wafer 20 according to the control of the control unit 8 to thereby perform alignment. More specifically, in this step, the control unit 8 controls the imaging unit 5 to thereby image the functional element layer 22.

On the other hand, in the laser processing device 1 (for example, the control unit 8), the size of the functional element 22a (tool size), the workpiece size of the wafer 20 (the size of the processing range), and the functional element layer 22 are registered in advance. Initial information of the reference image. Next, the control unit 8 aligns the irradiation position of the laser light L (the position of the laser irradiation unit 3 in the X direction and the Y direction) based on the image obtained by the imaging unit 5 and the initial information.

In the next step, the control unit 8 controls the drive unit 7 to thereby set the processing height (position in the Z direction) of the laser irradiation unit 3 (S12). Next, the control unit 8 starts the formation of the modified regions 12a and 12b (S13). Here, as an example, processing is performed along the first line 15a. That is, in this step, the laser processing apparatus 1 irradiates the wafer 20 with laser light L from the back surface 21b side of the semiconductor substrate 21 along a first line 15a, thereby making a laser beam L along the first line 15a. Two rows of modified regions 12a and 12b are formed inside the semiconductor substrate 21.

Next, the control unit 8 determines whether the position of the first line 15a is at a preset alignment position after the processing of one first line 15a is completed (S14). The alignment here is a realignment for correcting the displacement generated by the alignment performed in step S11. Although this realignment can be performed every time the processing of one first wire 15a is completed, it is more efficient to perform it after completing a plurality of first wires 15a. That is, although the alignment position can be set individually for each first line 15a, it is more efficient to set one for a plurality of first lines 15a.

In this step, if the position of the first line 15a processed in step S13 is not the alignment position, return to step S13 and continue to form modified regions 12a and 12b along the other first lines 15a. On the other hand, in this step, if the position of the first line 15a processed in step S13 is aligned with the position, then the alignment is performed again. That is, in this case, it is an opportunity to temporarily stop the formation of the modified regions 12a and 12b and perform alignment.

In the next step, re-alignment is performed as described above (the control unit 8 performs alignment processing) (S15). An example of alignment here is as follows. That is, the control unit 8 controls the imaging unit 5, thereby imaging the functional element layer 22 at the alignment correction position. In addition, the control unit 8 controls the imaging unit 5 to thereby image the area including the modified areas 12a and 12b at the position. Next, the control unit 8 detects the shift amount of the modified regions 12a and 12b from the predetermined position (for example, the center position) of the ruled line region 23 based on the two images. The control unit 8 realigns the irradiation position of the laser light L based on the detected shift amount.

Or, another example of alignment here is as follows. That is, the control unit 8 controls the imaging unit 5, thereby imaging the functional element layer 22 at the alignment correction position. Next, the control unit 8 pattern-matches the image of the functional element layer 22 at the alignment correction position acquired in advance before processing with the image of the functional element layer 22 acquired in this step, thereby detecting alignment marks, etc. The offset between the feature points. The control unit 8 adjusts the irradiation position of the laser light L based on the detected offset amount.

In the next step, the control unit 8 determines whether or not the formation of the modified regions 12a and 12b has been completed along all the first lines 15a (S16). If the result of this determination is that the formation of the modified regions 12a and 12b has not been completed along all the first lines 15a, the process returns to step S13 and continues to form the modified regions 12a and 12b along the remaining first lines 15a. On the other hand, if the result of this determination is that the formation of the modified regions 12a and 12b is completed along all the first lines 15a, the formation of the modified regions 12a and 12b along the second lines 15b is started. That is, in this case, the formation of modified regions 12a, 12b is temporarily stopped, and the modified regions 12a, 12b are formed along the first line 15a and the modified regions 12a, 12b are formed along the second line 15b. opportunity.

That is, in the next step, the laser processing device 1 irradiates the wafer 20 with laser light L from the back surface 21b side of the semiconductor substrate 21 along a second line 15b, thereby along the second line 15b. In 15b, two rows of modified regions 12a and 12b are formed inside the semiconductor substrate 21 (S17).

Next, the control unit 8 determines whether or not the position of the second wire 15b is at a preset alignment position after the processing of one second wire 15b is completed (S18). The alignment here is a realignment for correcting the displacement generated by the alignment performed in step S15. Although this realignment can be performed every time the processing of one second wire 15b is completed, it is more efficient to perform it after completing a plurality of second wires 15b. That is, although the alignment position can be individually set for each second line 15b, it is more efficient to set one for a plurality of second lines 15b.

In this step, if the position of the second line 15b processed in step S17 is not the alignment position, return to step S17 and continue to form modified regions 12a and 12b along the other second lines 15b. On the other hand, in this step, if the position of the second line 15b processed in step S17 is aligned with the position, then the alignment is performed again. That is, in this case, it is an opportunity to temporarily stop the formation of the modified regions 12a and 12b and perform alignment.

In the next step, re-alignment is performed as described above (S19). The form of alignment here is the same as in step S15.

In the next step, the control unit 8 determines whether or not the formation of the modified regions 12a and 12b is completed along all the second lines 15b (S20). If the result of this determination is that the formation of the modified regions 12a and 12b has not been completed along all the second lines 15b, the process returns to step S17 and continues to form the modified regions 12a and 12b along the remaining second lines 15b. On the other hand, if the result of this determination is that the formation of the modified regions 12a and 12b is completed along all the second lines 15b, the second inspection is performed.

That is, in the next step, the control unit 8 images the wafer 20 by controlling the imaging unit 4 (S21, first imaging step). Here, the control unit 8 relatively moves the focal point F in the Z direction within the wafer 20 by moving the imaging unit 4 in the Z direction. Thereby, the imaging unit 4 can capture images in each part in the Z direction to obtain an image. Therefore, the obtained image may include only the modified regions 12a and 12b, may include the modified regions 12a, 12b and the crack 14, or may only include the crack 14.

Here, the imaging unit 4 captures the area of the side corresponding to the first line 15a of the functional element 22a viewed from the Z direction. That is, here, the control unit 8 executes the first imaging process (the first imaging step) after the modified regions 12a and 12b are formed along the first line 15a and the second line 15b. The first imaging process is The area corresponding to the side of the first line 15a of the functional element 22a viewed from the Z direction by imaging and is the modified area 12a, 12b and/or the area including the crack 14 extending from the modified area 12a, 12b Method, control the camera unit 4. The image obtained in this step is provided to the control unit 8. Therefore, the control unit 8 can perform the second inspection based on the supplied image data and based on the aforementioned method and principle.

After this step, the control unit 8 executes the second imaging process (second imaging step) after forming modified regions 12a and 12b along the first line 15a and the second line 15b. , The area corresponding to the side of the second line 15b of the functional element 22a viewed from the Z direction by imaging and is the modified area 12a, 12b and/or the area including the crack 14 extending from the modified area 12a, 12b Way to control the camera unit 4. The image obtained in this step is provided to the control unit 8. Therefore, the control unit 8 can perform the second inspection based on the supplied image data and based on the aforementioned method and principle.

In addition, in the laser processing method and imaging method described above using FIG. 18, the second inspection is exemplified as the inspection of the crack 14. However, it is not limited to the second inspection, and may be the first inspection, the third inspection, or the second inspection. 4 check.

[Functions and effects of laser processing methods and semiconductor device manufacturing methods]

In the aforementioned laser processing method, the focal point F is focused from the back surface 21b side of the semiconductor substrate 21 to the inspection area R2 between the modified area 12a and the modified area 12b, and it is detected from the surface 21a side to the back surface 21b The light I1 propagates (transmits) on the side of the semiconductor substrate 21. By detecting such light I1, when the tip 14e of the crack 14b extending from the modified region 12a to the back 21b side exists in the inspection region R2, the tip 14e of the crack 14b can be confirmed. In addition, in the case where the tip 14e of the crack 14b exists in the inspection region R2, it is assumed that the crack 14 spanning the two rows of modified regions 12a and 12b does not reach the surface 21a of the semiconductor substrate 21. Thereby, according to the aforementioned laser processing method, it can be confirmed whether the crack 14 spanning the two rows of modified regions 12a, 12b reaches the surface 21a of the semiconductor substrate 21.

In addition, in the aforementioned laser processing method, two rows of modified regions 12a, 12b are formed as a plurality of rows of modified regions 12. Thereby, it is possible to efficiently perform the formation of a plurality of rows of modified regions 12 and the inspection of cracks 14 across the plurality of rows of modified regions 12.

In addition, according to the aforementioned semiconductor device manufacturing method, when it is estimated that the crack 14 that spans the two rows of modified regions 12a, 12b does not reach the surface 21a of the semiconductor substrate 21, the grinding of the inner surface 21b of the semiconductor substrate 21 is not performed. Therefore, it can be prevented that the wafer 20 cannot be reliably cut along the plurality of lines 15 after the grinding step.

The aforementioned imaging device 10 captures the modified regions 12a, 12b formed on the object 11 (semiconductor substrate 21 of the wafer 20) and/or cracks extending from the modified regions 12a, 12b by irradiating laser light L 14. The imaging device 10 includes an imaging unit 4 for imaging the wafer 20 by light I1 penetrating at least a semiconductor substrate 21 of the wafer 20 and a control unit 8 for controlling the imaging unit 4. The wafer 20, viewed from the Z direction, includes a plurality of functional elements 22a defined by the first line 15a and the second line 15b. The control unit 8 executes the first imaging process after the modified regions 12a and 12b are formed along the first line 15a and the second line 15b. The first imaging process corresponds to the functional element viewed from the Z direction. The imaging unit 4 is controlled so that the area on the side of the first line 15a of 22a is the modified area 12a, 12b and/or the area including the crack 14 extending from the modified area 12a, 12b.

In the imaging device 10, the control unit 8 executes a first imaging process that uses light I1 penetrating the semiconductor substrate 21 to image the modified regions 12a, 12b of the semiconductor substrate 21 and/or include The area of the crack 14 extending from the modified areas 12a, 12b. Therefore, it is possible to obtain images of modified regions 12a, 12b, etc. (modified regions 12a, 12b and/or cracks 14 extending from modified regions 12a, 12b (the same below)) without damaging the wafer 20. And be able to confirm. In particular, in the imaging device 10, the control unit 8 executes the aforementioned first imaging process after forming modified regions 12a and 12b on the object along the first line 15a and the second line 15b. Therefore, without affecting the speed of forming the modified regions 12a, 12b, the modified regions 12a, 12b, etc. can be confirmed. That is, according to the imaging device 10, it is possible to suppress a decrease in processing efficiency and to perform confirmation in a non-destructive manner. In addition, in the imaging device 10, the area captured by the first imaging process is formed on the side of the functional element 22 a of the wafer 20. The side of the functional element 22a is compared to the functional element 22a in which the modified regions 12a, 12b, etc. formed along the first line 15a intersect with the modified regions 12a, 12b, etc. formed along the second line 15b There is a tendency for the quality of the modified regions 12a, 12b, etc. to be higher. Therefore, according to the imaging device 10, the modified regions 12a, 12b, etc. can be confirmed with high accuracy.

In addition, in the imaging device 10, the control unit 8 may execute a second imaging process after the modified regions 12a and 12b are formed along the first line 15a and the second line 15b. The second imaging process is The area corresponding to the side of the second line 15b of the functional element 22a viewed from the Z direction by imaging and is the modified area 12a, 12b and/or the area including the crack 14 extending from the modified area 12a, 12b Method, control the camera unit 4. At this time, it is possible to suppress a decrease in processing efficiency, and it is possible to non-destructively confirm the modified regions 12a, 12b, etc. formed along the lines 15 intersecting each other.

The aforementioned laser processing device 1 is provided with: the aforementioned imaging device 10; a laser irradiation unit 3 for irradiating the wafer 20 with laser light L; and a drive unit 7, which is equipped with the laser irradiation unit 3, The laser irradiation unit 3 is driven in the Z direction. The imaging unit 4 is mounted on the drive unit 7 together with the laser irradiation unit 3.

The laser processing device 1 is equipped with the aforementioned imaging device 10 device. Therefore, according to the laser processing apparatus 1, it is possible to suppress the reduction in processing efficiency and to perform confirmation in a non-destructive manner. In addition, the laser processing device 1 includes a drive unit 7 that drives the laser irradiation unit 3 in the Z direction. In addition, the imaging unit 4 is attached to the drive unit 7 together with the laser irradiation unit 3. Therefore, in the formation of modified regions 12a and 12b by irradiating the laser light L and the first imaging process, the position information of the incident direction can be easily shared.

In addition, the laser processing apparatus 1 includes an imaging unit 5 for imaging the wafer 20 by light I2 penetrating the semiconductor substrate 21, and a control unit 8 for controlling the laser irradiation unit 3 and the imaging unit 5. The imaging unit 4 has an objective lens 43 that allows light I1 that has passed through the semiconductor substrate 21 to pass through, and a light detection unit 44 that detects the light I1 that has passed through the objective lens 43. The imaging unit 5 has a lens 53 for passing the light I2 that has passed through the semiconductor substrate 21, and a light detecting section 54 that detects the light I2 that has passed through the lens 53. The control unit 8 executes alignment processing that controls the laser irradiation unit 3 and the imaging unit 5 in such a way that the irradiation position of the laser light L is aligned based on the detection result of the light detection unit 54. Therefore, in addition to the imaging unit 4 for imaging the modified regions 12a, 12b, etc., an imaging unit 5 for aligning the irradiation position of the laser light L is additionally used, whereby respective appropriate optical systems can be used.

In addition, in the laser processing apparatus 1, the numerical aperture of the objective lens 43 is larger than the numerical aperture of the lens 53. At this time, the alignment can be performed more reliably by observation of a relatively small numerical aperture, and the modified regions 12a, 12b, etc. can be imaged with a relatively large numerical aperture.

The aforementioned imaging method is used to capture the modified regions 12a and 12b formed on the semiconductor substrate 21 by irradiating laser light L and/or the cracks 14 extending from the modified regions 12a and 12b. The imaging method is a first imaging step including the imaging wafer 20. The wafer 20, viewed from the Z direction, includes a plurality of functional elements 22a defined by the first line 15a and the second line 15b. In the first imaging step, after the modified regions 12a and 12b are formed along the first line 15a and the second line 15b, the region corresponding to the side of the first line 15a of the functional element 22a is captured from the Z direction. These are modified regions 12a, 12b and/or regions including cracks 14 extending from the modified regions 12a, 12b.

In this method, the modified regions 12a, 12b of the semiconductor substrate 21 and/or the regions including the cracks 14 extending from the modified region 12a are captured by light I1 penetrating the semiconductor substrate 21. Therefore, the modified regions 12a, 12b, etc. can be confirmed without destroying the wafer 20. In particular, in this method, the aforementioned imaging is performed after the modified regions 12a and 12b are formed along the first line 15a and the second line 15b. Therefore, without affecting the speed of forming the modified regions 12a, 12b, the modified regions 12a, 12b, etc. can be confirmed. That is, according to this method, it is possible to suppress a decrease in processing efficiency and to perform confirmation in a non-destructive manner. In addition, in this method, the area to be imaged is the side portion of the functional element 22 a formed in the wafer 20. In terms of the side portion of the functional element 22a, compared to the functional element in which the modified regions 12a, 12b, etc. formed along the first line 15a intersect with the modified regions 12a, 12b, etc. formed along the second line 15b The corner portions of 22a tend to have high quality in modified regions 12a and 12b. Therefore, according to this method, the modified regions 12a, 12b, etc. can be confirmed with high accuracy.

In addition, the aforementioned imaging method further includes a second imaging step of imaging the wafer 20. In the second imaging step, after the modified regions 12a and 12b are formed along the first line 15a and the second line 15b, the side corresponding to the second line 15b of the functional element 22a may be captured from the Z direction. The regions are modified regions 12a, 12b and/or regions including cracks 14 extending from the modified regions 12a, 12b. At this time, it is possible to suppress reduction in processing efficiency, and to confirm the modified regions 12a, 12b, etc. formed along lines that cross each other in a non-destructive manner. [Modifications]

One aspect of this disclosure is not limited to the aforementioned embodiment. For example, in the foregoing embodiment, the laser processing device 1 forms two rows of modified regions 12a, 12b inside the semiconductor substrate 21 along a plurality of lines 15 respectively. However, the laser processing device 1 can also be used along The plurality of wires 15 form one row or more than three rows of modified regions 12 in the semiconductor substrate 21. The number of columns and positions of the modified regions 12 formed by one line 15 can be appropriately set in consideration of the thickness of the semiconductor substrate 21 of the wafer 20 and the thickness of the semiconductor substrate 21 of the semiconductor device 20a. In addition, multiple rows of modified regions 12 can also be formed by performing relative movement of the condensing point C of the laser light L to one line 15 multiple times.

In addition, in the grinding and cutting step of step S06 shown in FIG. 15, the grinding device 200 can also grind the back surface 21 b of the semiconductor substrate 21 beyond the reference position P. The planned grinding end position can be appropriately set depending on whether or not the modified region 12 is left on the side surface (cut surface) of the semiconductor device 20a. Furthermore, when the semiconductor device 20a is, for example, a DRAM (Dynamic Random Access Memory), the modified region 12 may be left on the side surface of the semiconductor device 20a.

In addition, as shown in FIG. 19, the imaging device 10 may be configured to be a different entity from the laser processing device 1. The imaging device 10 shown in FIG. 19 includes a stage 101, a drive unit 102, and a control unit (first control unit) 103 in addition to the imaging unit 4. The stage 101 is configured to be the same as the above-mentioned stage 2 and supports a wafer 20 on which a plurality of rows of modified regions 12 are formed. The driving unit 102 supports the imaging unit 4 and moves the imaging unit 4 in the Z direction. The control unit 103 has the same configuration as the control unit 8 described above. The laser processing system shown in FIG. 19 is between the laser processing device 1 and the imaging device 10, and the wafer 20 is transferred by a transfer device such as a robot arm.

In addition, the irradiation conditions of the laser light L when the laser light L is irradiated to the wafer 20 from the back surface 21b side of the semiconductor substrate 21 along the plurality of lines 15 are not limited to those described above. For example, the irradiation conditions of the laser light L are as described above, so that the cracks 14 spanning a plurality of rows of modified regions 12 (for example, two rows of modified regions 12a, 12b) reach the semiconductor substrate 21 and the functional element layer 22 The conditions of the interface are also possible. Alternatively, the irradiation conditions of the laser light L may be such that the cracks 14 spanning the plurality of rows of modified regions 12 reach the surface of the functional element layer 22 on the opposite side to the semiconductor substrate 21. Alternatively, the irradiation conditions of the laser light L may be such that the cracks 14 spanning the plurality of rows of modified regions 12 reach the vicinity of the inner surface 21 a of the semiconductor substrate 21. In this way, the irradiation condition of the laser light L may be a condition for forming the cracks 14 that straddle the plurality of rows of modified regions 12. In any case, it can be confirmed whether the cracks 14 spanning the plurality of rows of modified regions 12 sufficiently extend to the surface 21 a side of the semiconductor substrate 21.

In addition, each configuration in the aforementioned embodiment is not limited to the aforementioned materials and shapes, and various materials and shapes can be used. In addition, each configuration in one of the aforementioned embodiments or modifications can be arbitrarily applied to each configuration in other embodiments or modifications. [Possibility of industrial use]

It is possible to provide an imaging device, a laser processing device, and an imaging method that can suppress a decrease in processing efficiency and can perform confirmation in a non-destructive manner.

1: Laser processing device 3: Laser irradiation unit 4: Camera unit (1st camera unit) 5: Camera unit (2nd camera unit) 7: Drive unit 8: Control part (1st control part, 2nd control part) 10: Camera 12, 12a, 12b: modified area 11: Object 14: Cracking 15a: Line 1 15b: Line 2

[Fig. 1] is a configuration diagram of a laser processing device equipped with an inspection device of an embodiment. [Fig. 2] A plan view of a wafer according to an embodiment. [Fig. 3] is a cross-sectional view of a part of the wafer shown in Fig. 2. [Fig. [Fig. 4] is a configuration diagram of the laser irradiation unit shown in Fig. 1. [Fig. 5] is a block diagram of the imaging unit for inspection shown in Fig. 1. [Fig. 6] is a configuration diagram of the imaging unit for alignment correction shown in Fig. 1. [Fig. [FIG. 7] A cross-sectional view of a wafer for explaining the imaging principle of the inspection imaging unit shown in FIG. 5, and images of various parts obtained by the inspection imaging unit. [FIG. 8] A cross-sectional view of a wafer for explaining the imaging principle of the inspection imaging unit shown in FIG. 5, and images of various parts obtained by the inspection imaging unit. [Figure 9] SEM (Scanning Electron Microscope) images of modified regions and cracks formed inside the semiconductor substrate. [Fig. 10] An SEM image of modified regions and cracks formed inside the semiconductor substrate. [FIG. 11] It is an optical path diagram for explaining the imaging principle of the imaging unit for inspection shown in FIG. 5, and a schematic diagram showing the image of the focal point of the imaging unit for inspection. [FIG. 12] It is a light path diagram for explaining the imaging principle of the imaging unit for inspection shown in FIG. 5, and a schematic diagram showing the image of the focal point of the imaging unit for inspection. [FIG. 13] A cross-sectional view of a wafer, an image of a cut surface of the wafer, and a diagram of each part obtained by the inspection imaging unit for explaining the inspection principle of the inspection imaging unit shown in FIG. 5 Like. [FIG. 14] A cross-sectional view of a wafer, an image of a cut surface of the wafer, and a diagram of each part obtained by the inspection imaging unit for explaining the inspection principle of the inspection imaging unit shown in FIG. 5 Like. Fig. 15 is a flowchart of a method of manufacturing a semiconductor device according to an embodiment. [Fig. 16] is a cross-sectional view of a part of the wafer in the grinding and cutting step of the semiconductor device manufacturing method shown in Fig. 15. [Fig. [FIG. 17] A cross-sectional view of a part of the wafer in the grinding and cutting step of the semiconductor device manufacturing method shown in FIG. 15. Fig. 18 is a flowchart showing a laser processing method and an imaging method according to an embodiment. [FIG. 19] A configuration diagram of a laser processing system equipped with an imaging device of a modification.

Claims (7)

An imaging device for imaging a modified area formed by irradiating a laser light on an object and/or a crack extending from the modified area; it is characterized by: having: The first imaging unit captures the object by light penetrating the object; and The first control unit controls the aforementioned first imaging unit; The object, as viewed from a direction crossing the incident surface of the laser light, includes a plurality of functional elements defined by a first line and a second line crossing the first line, The first control unit executes a first imaging process after forming the modified region along the first line and the second line, and the first imaging process corresponds to the function described above by imaging viewed from the aforementioned direction The first imaging unit is controlled in such a way that the area on the side of the first line of the element is the modified area and/or the area including the crack extending from the modified area. The camera device according to claim 1, wherein: The first control unit executes a second imaging process after forming the modified region along the first line and the second line, and the second imaging process corresponds to the aforementioned function by imaging the observation from the aforementioned direction The area of the side of the second line of the element is the modified area and/or the area including the crack extending from the modified area, and the first imaging unit is controlled. A laser processing device with: The camera device described in claim 1 or 2; The laser irradiation unit is used to irradiate the laser light on the object; and The driving unit is equipped with the laser irradiation unit, and drives the laser irradiation unit in a direction crossing the incident surface of the laser light of the object; The first imaging unit is attached to the drive unit together with the laser irradiation unit. The laser processing device according to claim 3, wherein: The second imaging unit captures the object by light penetrating the object; and The second control unit controls the laser irradiation unit and the second imaging unit; The first imaging unit includes: a first lens that passes light that has passed through the object; and a first light detection unit that detects the light that has passed through the first lens; The second imaging unit includes: a second lens that passes light that has passed through the object; and a second light detection unit that detects the light that has passed through the second lens; The second control unit executes an alignment process that controls the laser irradiation unit and the second laser light to align the laser light irradiation position based on the detection result of the second light detection unit Camera unit. The laser processing device according to claim 4, wherein: The numerical aperture of the first lens is larger than the numerical aperture of the second lens. An imaging method for imaging a modified area formed by irradiating a laser light on an object and/or a crack extending from the modified area; the feature is: The first imaging step is imaging the aforementioned object; The object, as viewed from a direction crossing the incident surface of the laser light, includes a plurality of functional elements defined by a first line and a second line crossing the first line, In the first imaging step, after forming modified regions along the first line and the second line, the region corresponding to the side of the first line of the functional element viewed from the above direction is imaged and is the above The modified region and/or the region including the aforementioned cracks extending from the modified region. The photographing method according to claim 6, wherein: The second imaging step is to capture the aforementioned object; In the second imaging step, after the modified region is formed along the first line and the second line, the region corresponding to the side of the second line of the functional element viewed from the above direction is imaged and is the above The modified region and/or the region including the aforementioned cracks extending from the modified region.

Images