Object processing method

Abstract

This object processing method comprises a modified region formation step for forming a plurality of rows of modified regions in a thickness direction inside a first substrate by irradiating the first substrate with laser light along a planned cutting line. In the modified region formation step, when a modified region closest to a functional element layer among the plurality of rows of modified regions is formed in the first substrate, laser light having an energy equal to or greater than a predetermined threshold value is emitted along a first portion of the planned cutting line, and laser light having an energy less than the predetermined threshold value is emitted, or no laser light is emitted, along a second portion which is different from the first portion of the planned cutting line and which corresponds to a portion to be observed of the functional element layer.

Description

Method of processing the object

[0001] The present disclosure relates to a method for processing an object.

[0002] In an object (such as a bonded wafer) including a first substrate and a second substrate stacked on the first substrate with a functional device layer interposed therebetween, if an abnormality or the like occurs in the functional device layer, a destructive inspection such as cross-sectional structure analysis may be performed to observe the functional device layer. As an example of this type of technology, Patent Document 1 discloses a method in which an energy beam is irradiated along a cleavage plane to a portion of a semiconductor substrate excluding a predetermined portion to be observed, thereby forming a damaged layer on the surface of the semiconductor substrate, and the semiconductor substrate is cut along the damaged layer to obtain a cross section of the predetermined portion.

[0003] Japanese Patent Application Publication No. 6-244256

[0004] As a technique for observing the functional element layer, an object processing method has been developed in which a laser beam is irradiated into the object to form a modified region, a crack is propagated from the modified region, and the object is cut so that the intended observation portion of the functional element layer becomes observable. In this case, for example, as shown in FIG. 25 , when an object 920 such as a bonded wafer (i.e., an object 920 including a first substrate 921 and a second substrate 922 stacked on the first substrate 921 via a functional element layer 923) is subjected to laser processing, the crack is likely to bend in the functional element layer 923. This may result in a deterioration in the quality of the cut surface of the functional element layer 923, making good observation difficult. In this case, it is important to prevent damage caused by the formation of the modified region from reaching the intended observation portion in order to ensure good observation.

[0005] The present disclosure aims to provide an object treatment that allows good observation of a functional element layer.

[0006] The object processing method disclosed herein is [1] "an object processing method for processing an object including a first substrate and a second substrate stacked on the first substrate via a functional element layer, comprising a modified region forming step of forming multiple rows of modified regions in the thickness direction inside the first substrate by irradiating the first substrate with laser light along a planned cutting line, wherein in the modified region forming step, when forming the modified region closest to the functional element layer among the multiple rows of the modified regions in the first substrate, the laser light having an energy equal to or greater than a predetermined threshold is irradiated along a first part of the planned cutting line, and the laser light having an energy less than the predetermined threshold is irradiated or the laser light is not irradiated along a second part different from the first part of the planned cutting line and corresponding to the planned observation location of the functional element layer."

[0007] In this object processing method, when forming the modified region closest to the functional device layer, laser light having an energy equal to or greater than a predetermined threshold is irradiated along a first portion of the line to cut. This reliably forms the modified region closest to the functional device layer and allows a crack to propagate from the modified region into the functional device layer. This increases the linearity of the crack propagating through the functional device layer, thereby improving the quality of the cut surface of the functional device layer. Meanwhile, when forming the modified region closest to the functional device layer, the energy of the irradiated laser light is set below a predetermined threshold or laser light is not irradiated along a second portion of the line to cut. This prevents a modified region that could damage the intended observation location from being formed too close to the intended observation location, thereby preventing damage to the intended observation location. This enables good observation of the functional device layer.

[0008] The object processing method of the present disclosure may be [2] "the object processing method described in [1] above, wherein, in the modified region forming step, when forming the modified region closest to the functional device layer among the multiple rows of the modified regions on the first substrate, the pulsed laser light is irradiated along the first portion, and the laser light is not irradiated along the second portion." In this case, when forming the modified region closest to the functional device layer on the first substrate, it is possible to reliably achieve not forming a modified region along the second portion.

[0009] The object processing method of the present disclosure may be [3] "the object processing method described in [1] above, wherein, in the modified region forming step, when forming the modified region closest to the functional element layer among the multiple rows of the modified regions on the first substrate, the pulsed laser light is irradiated along the first portion and the second portion." In this case, the output of the laser light can be stabilized.

[0010] The object processing method of the present disclosure may be [4] "the object processing method described in [1] above, wherein, in the modified region forming step, when forming the modified region closest to the functional device layer among the multiple rows of the modified regions on the first substrate, the pulsed laser light is irradiated along the first portion and the continuous laser light is irradiated along the second portion." In this case, when forming the modified region closest to the functional device layer on the first substrate, it is possible to reliably achieve not forming a modified region along the second portion.

[0011] The object processing method of the present disclosure may be [5] "the object processing method according to any one of [1] to [4] above, further comprising, before the modified area forming step, a step of specifying a planned observation area of ​​the functional device layer, wherein, in the modified area forming step, the first portion and the second portion are set based on the result of the specification in the planned observation area specifying step." In this case, the first portion and the second portion can be set using the result of the specification in the planned observation area specifying step.

[0012] The object processing method of the present disclosure may be [6] "the object processing method according to any one of [1] to [5] above, including: a cutting step of cutting the object along the planned cutting line after the modified region forming step; and a planned observation portion observing step of observing the planned observation portion of the functional element layer after the cutting step." In this case, in the planned observation portion observing step, the planned observation portion can be observed with high positional accuracy by referring to a portion of the first substrate of the object after cutting that is not irradiated with laser light or a portion that is irradiated with laser light with energy less than a predetermined threshold (i.e., a portion where no modified region that could damage the planned observation portion is formed).

[0013] The object processing method of the present disclosure may be [7] "the object processing method described in the above [6], wherein in the step of observing the intended observation portion, the intended observation portion of the functional element layer is observed based on a window portion including a region corresponding to the second portion between a pair of the modified regions formed along the first portion." In this case, in the step of observing the intended observation portion, the intended observation portion can be easily identified, for example, even at low magnification, by referring to the window portion.

[0014] The object processing method of the present disclosure may be [8] the object processing method described in any one of [1] to [7] above, wherein in the modified region forming step, the second substrate is irradiated with the laser light along the line to cut, thereby forming one row or multiple rows of the modified regions in the thickness direction within the second substrate, and when forming the modified region closest to the functional device layer among the one or multiple rows of the modified regions in the second substrate, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a third portion of the line to cut, and the laser light having an energy less than the predetermined threshold is irradiated or the laser light is not irradiated along a fourth portion, different from the first portion of the line to cut and corresponding to the intended observation location of the functional device layer. In this case, it is possible to easily cut the object by utilizing cracks extending from the modified regions formed in the second substrate, while suppressing the formation of modified regions in the second substrate that may damage the intended observation location.

[0015] The object processing method of the present disclosure may be the object processing method described in [8] above, [9] in which "in the modified region forming step, the first substrate is irradiated with the laser light along the line to cut to form some of the modified regions in multiple rows inside the first substrate, the second substrate is irradiated with the laser light along the line to cut to form the multiple rows of the modified regions inside the second substrate, and the first substrate is irradiated with the laser light to form other portions of the modified regions in multiple rows inside the first substrate." This makes it possible to suppress processing effects such as warping that occur in the object due to the formation of the modified regions when performing laser processing to form multiple rows of modified regions in the first substrate and the second substrate.

[0016] The object processing method of the present disclosure may be

[10] "the object processing method described in [8] above, wherein in the modified region forming step, the first substrate is irradiated with the laser light along the line to cut to form a plurality of rows of the modified regions inside the first substrate, and the second substrate is irradiated with the laser light along the line to cut to form a plurality of rows of the modified regions inside the second substrate." This makes it possible, for example, to reduce the frequency of turning over the object and shorten the processing time when performing laser processing to form a plurality of rows of modified regions in the first substrate and the second substrate.

[0017] The object processing method of the present disclosure may be

[11] "the object processing method described in [8] above, wherein in the modified region forming step, the second substrate is irradiated with the laser light along the line to cut to form one row of the modified regions inside the second substrate, and the first substrate is irradiated with the laser light along the line to cut to form multiple rows of the modified regions inside the first substrate." This makes it possible to shorten the processing time for laser processing the second substrate when performing laser processing to form modified regions in the first substrate and the second substrate.

[0018] The object processing method of the present disclosure may be

[12] "the object processing method described in [8] to

[11] above, wherein the first substrate has a larger inclination angle of the cleavage direction relative to the extension direction of the line to cut than the second substrate and / or is thicker than the second substrate, and the number of rows of the modified regions formed in the first substrate is greater than the number of rows of the modified regions formed in the second substrate." In this case, the number of rows of modified regions formed in the first substrate, in which cracks are less likely to propagate along the line to cut, can be increased, making it possible to reliably cut the first substrate.

[0019] The object processing method of the present disclosure may be

[13] "the object processing method described in any one of [8] to

[12] above, which includes, after the modified region forming step, a cutting step of applying stress to the object to cut the object along the line to cut, wherein the number of rows of the modified regions formed on the first substrate is different from the number of rows of the modified regions formed on the second substrate, and in the cutting step, the stress is applied from one of the first substrate and the second substrate on which the number of rows of the modified regions formed is fewer." In this case, it is possible to reliably cut the object along the line to cut.

[0020] The object processing method of the present disclosure may be

[14] "the object processing method according to any one of [1] to [7] above, wherein in the modified region forming step, the modified region is formed only inside the first substrate." This eliminates the need for laser processing to form the modified region in the second substrate, thereby shortening the processing time.

[0021] The object processing method of the present disclosure may be

[15] "the object processing method described in

[14] above, which includes, after the modified region forming step, a cutting step of applying stress to the object to cut the object along the line to cut, wherein the stress is applied from the second substrate side in the cutting step." In this case, it is possible to reliably cut the object along the line to cut.

[0022] The object processing method of the present disclosure may be

[16] "the object processing method according to any one of [1] to

[15] above, which includes an interior observation step of observing the interior of the object, wherein the interior observation step observes the presence or absence of modified spots in regions of the first substrate irradiated with the laser light having an energy equal to or greater than the predetermined threshold, and observes the presence or absence of cracks in regions of the first substrate irradiated with the laser light having an energy less than the predetermined threshold or not irradiated with the laser light." In this case, whether or not laser processing has been properly performed on the first substrate can be confirmed by observing the interior of the object.

[0023] The object processing method of the present disclosure may be

[17] "the object processing method according to any one of [1] to

[16] above, wherein the predetermined threshold corresponds to the minimum energy at which the laser light irradiation can form the modified region and a crack extending from the modified region toward the functional element layer." In this case, it is possible to reliably form a modified region along the first part of the line to cut, and to reliably prevent the formation of a modified region that could damage the intended observation location along the second part of the line to cut.

[0024] The object processing method of the present disclosure may be

[18] "the object processing method according to any one of [1] to

[17] above, wherein the planned cutting line is set to overlap the planned observation location of the functional element layer when viewed from the thickness direction of the object." In this case, it becomes possible to easily observe the planned observation location from the cut surface of the object after cutting.

[0025] The object processing method of the present disclosure may be

[19] "the object processing method according to any one of [1] to

[18] above, in which, when the object is viewed from the thickness direction, the planned cutting line is set to be spaced apart from the planned observation location of the functional element layer." In this case, it becomes possible to transmit and observe the planned observation location from the cut surface of the object after cutting using, for example, X-rays or the like.

[0026] The object processing method of the present disclosure may be

[20] "the object processing method described in

[19] above, including a cutting step of cutting the object along the planned cutting line after the modified region forming step, and a planned observation portion observing step of observing the planned observation portion of the functional element layer while removing the object from the cut surface toward the planned observation portion after the cutting step." In this case, observation accuracy can be further improved. Also, for example, three-dimensional observation of the planned observation portion becomes possible.

[0027] The object processing method of the present disclosure may be

[21] "the object processing method according to any one of [1] to

[20] above, wherein in the modified region forming step, when another modified region adjacent to the modified region closest to the functional device layer among the multiple rows of the modified regions is formed on the first substrate, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a fifth portion of the line to cut, and the laser light having an energy less than the predetermined threshold is irradiated or the laser light is not irradiated along a sixth portion different from the fifth portion of the line to cut and corresponding to the intended observation location of the functional device layer, and at least a portion of the sixth portion overlaps the second portion." Even in this case, it is possible to increase the straightness of cracks extending in the functional device layer and improve the quality of the cut surface of the functional device layer, while suppressing the formation of modified regions that may damage the intended observation location and cause damage to the intended observation location.

[0028] The object processing method of the present disclosure includes,

[22] "the modified region forming step forms a plurality of rows of the modified regions in a thickness direction inside the second substrate by irradiating the second substrate with the laser light along the line to cut, and when forming the modified region closest to the functional device layer among the plurality of rows of the modified regions on the second substrate, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a third portion of the line to cut, and the laser light having an energy less than the predetermined threshold is irradiated along a fourth portion of the line to cut that is different from the third portion and corresponds to a planned observation location of the functional device layer. Alternatively, the method for processing an object according to any one of [1] to [7] above may be such that, when forming another modified region on the second substrate adjacent to the modified region closest to the functional device layer among the multiple rows of modified regions without irradiating the laser light, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a seventh portion of the line to cut, and the laser light having an energy less than the predetermined threshold is irradiated or the laser light is not irradiated along an eighth portion different from the seventh portion of the line to cut and corresponding to the intended observation location of the functional device layer, and at least a portion of the eighth portion overlaps with the fourth portion. In this case, the object can be more easily cut (easily cracked) than when a single row of modified regions is formed inside the second substrate.

[0029] According to the present invention, it is possible to provide an object processing method that enables good observation of a functional element layer.

[0030] FIG. 1 is a plan view showing an object according to the first embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a flowchart showing an object processing method according to the first embodiment. FIG. 4(a) is a plan view of an object for explaining the intended observation position specifying step according to the first embodiment. FIG. 4(b) is a plan view showing a line to cut set on the object. FIG. 5 is a configuration diagram showing a laser processing apparatus. FIG. 6(a) is a cross-sectional view of an object for explaining the modified region forming step according to the first embodiment. FIG. 6(b) is a cross-sectional view showing a continuation of FIG. 6(a). FIG. 7(a) is a cross-sectional view showing a continuation of FIG. 6(b). FIG. 7(b) is a cross-sectional view showing a continuation of FIG. 7(a). FIG. 8(a) is a cross-sectional view showing a continuation of FIG. 7(b). FIG. 8(b) is a cross-sectional view showing a continuation of FIG. 8(a). FIG. 9(a) is a cross-sectional view showing a continuation of FIG. 8(b). FIG. 9(b) is a cross-sectional view showing a continuation of FIG. 9(a). FIG. 10(a) is a cross-sectional view showing a continuation of FIG. 9(b). FIG. 10(b) is a cross-sectional view showing a continuation of FIG. 9(a). FIG. 11 is a cross-sectional view showing a continuation of FIG. 10(b). FIG. 12(a) is a cross-sectional view of an object for explaining the cutting step according to the first embodiment. FIG. 12(b) is a perspective view showing a part of the observation chip according to the first embodiment. FIG. 13 is a photograph showing a window portion formed in the object of FIG. 1. FIG. 14(a) is a cross-sectional view of an object for explaining the modified region forming step according to the second embodiment. FIG. 14(b) is a cross-sectional view showing a continuation of FIG. 14(a). FIG. 15(a) is a cross-sectional view of an object for explaining the modified region forming step according to the third embodiment. FIG. 15(b) is a cross-sectional view showing a continuation of FIG. 15(a). FIG. 15(c) is a cross-sectional view of an object for explaining the cutting step according to the third embodiment. FIG. 16(a) is a cross-sectional view of an object for explaining the modified region forming step according to the fourth embodiment. Fig. 16(b) is a cross-sectional view of an object for explaining a cutting step according to the fourth embodiment. Fig. 17(a) is a plan view showing lines to cut set on an object in the fifth embodiment. Fig. 17(b) is a perspective view showing a part of an observation chip according to the fifth embodiment. Fig. 18(a) is a plan view showing lines to cut set on an object in the sixth embodiment.FIG. 18(b) is a plan view showing an observation chip according to the sixth embodiment. FIG. 19(a) is a cross-sectional view of an object for describing a modified region forming step according to a first modified example. FIG. 19(b) is a cross-sectional view of an object for describing a modified region forming step according to a second modified example. FIG. 20(a) is a cross-sectional view of an object for describing a modified region forming step according to a third modified example. FIG. 20(b) is a cross-sectional view of an object for describing a modified region forming step according to a fourth modified example. FIG. 21(a) is a cross-sectional view of an object for describing a modified region forming step according to a fifth modified example. FIG. 21(b) is a cross-sectional view of an object for describing a modified region forming step according to a sixth modified example. FIG. 22(a) is a cross-sectional view of an object for describing a modified region forming step according to a seventh modified example. FIG. 22(b) is a cross-sectional view of an object for describing a modified region forming step according to an eighth modified example. FIG. 22(c) is a cross-sectional view of an object for describing a modified region forming step according to a ninth modified example. FIG. 23 is a cross-sectional view of an object for describing a modified region forming step according to a tenth modified example. Fig. 24 is a configuration diagram showing a laser processing apparatus according to a modified example, and Fig. 25 is a photograph showing a cut surface of an object after cutting by a conventional object processing method.

[0031] Hereinafter, the embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0032] 1 and 2 , an object processing method according to the present embodiment is a method for processing an object such as a bonded wafer. As shown in FIG. 1 and FIG. 2 , an object 20 includes a first substrate 21 and a second substrate 22 stacked on the first substrate 21 with a functional device layer 23 interposed therebetween. Hereinafter, the Z direction corresponds to the thickness direction of the object 20, the X direction corresponds to the direction perpendicular to the Z direction, and the Y direction corresponds to the direction perpendicular to both the X direction and the Z direction.

[0033] The first substrate 21 and the second substrate 22 are, for example, semiconductor substrates, such as silicon (Si), glass, indium phosphide (InP), gallium nitride (GaN), silicon carbide (SiC), or LiTaO. ３ , and sapphire (Al２ O ３ ). The first substrate 21 and the second substrate 22 have a main surface that is a flat surface along the XY plane. At least one of the first substrate 21 and the second substrate 22 may be partially ground. The thicknesses of the first substrate 21 and the second substrate 22 may be the same as or different from each other. Either the first substrate 21 or the second substrate 22 may be formed from, for example, a glass base material.

[0034] For example, at least one of the first substrate 21 and the second substrate 22 may be a wafer with a crystal orientation of <100>0 degrees, in which case the plane perpendicular to the main surface is the (110) plane, and the cleavage direction is a direction along the lines to cut 15. Alternatively, for example, at least one of the first substrate 21 and the second substrate 22 may be a wafer with a crystal orientation of <100>45 degrees, in which case the plane perpendicular to the main surface is the (100) plane, and the cleavage direction is a direction intersecting the extension direction of the lines to cut 15. The cleavage directions of the first substrate 21 and the second substrate 22 are not particularly limited.

[0035] The functional element layer 23 is provided between the main surface of the first substrate 21 and the main surface of the second substrate 22. The functional element layer 23 may be composed of multiple layers bonded together. The functional element layer 23 includes multiple functional elements arranged two-dimensionally or three-dimensionally. The functional elements are, for example, light-receiving elements such as photodiodes, light-emitting elements such as laser diodes, and circuit elements such as memories. The target object 20 has a notch 20N indicating the crystal orientation, but an orientation flat may be provided instead of the notch 20N.

[0036] The object processing method of this embodiment observes a planned observation location K of the functional device layer 23 of the object 20. For example, if the object 20 is a bonded wafer that has undergone a bonding process in a semiconductor pre-processing step but has not yet undergone a grinding process, and in which an abnormality has been detected in an electrical characteristic measurement such as a probe test, the planned observation location K is the fault location. As shown in FIG. 3 , the object processing method includes a planned observation location identification step (step S1), a modified region formation step (step S2), an internal observation step (step S3), a cutting step (step S4), and a planned observation location observation step (step S5). The planned observation location K is not particularly limited and may be various locations.

[0037] 4A, in the process of specifying the planned observation location, a planned observation location K of the functional element layer 23 in the object 20 is specified using, for example, an ultrasonic microscope, a transmission type X-ray observation device, an X-ray CT (Computed Tomography) device, or an emission microscope. In the process of specifying the planned observation location K, information on the coordinates of the planned observation location K is acquired.

[0038] <Modified Area Forming Step and Internal Observation Step> In the modified area forming step and internal observation step, a laser processing device 1 shown in Fig. 5 is used to form a modified area inside the target object 20, and to observe the modified area formed inside the target object 20 and cracks extending from the modified area. First, the laser processing device 1 will be described.

[0039] The laser processing apparatus 1 includes a stage 2, a laser processing head 3, alignment cameras 5 and 6, an interior observation unit 4, a first vertical movement mechanism 7A, a second vertical movement mechanism 7B, a first horizontal movement mechanism 8A, a second horizontal movement mechanism 8B, a control unit 9, and a GUI (Graphical User Interface) 10. The laser processing apparatus 1 forms a modified region 12 (see FIG. 6( a) ) inside the object 20 by irradiating the object 20 with laser light L along a line to cut.

[0040] A row of modified regions 12 is a collection of multiple modified spots arranged in a row. One modified spot is formed by irradiating one pulse of laser light L. Adjacent modified spots may be connected to each other or separated from each other depending on the relative movement speed of the focusing position with respect to the target object 20 and the repetition frequency of the laser light L.

[0041] 4(b), the lines to be cut 15 include a pair of first lines to be cut 15a and a pair of second lines to be cut 15b that are perpendicular to the first lines to be cut 15a when viewed in the Z direction. The pair of first lines to be cut 15a extend in the X direction and are spaced apart from each other in the Y direction. The pair of second lines to be cut 15b extend in the Y direction and are spaced apart from each other in the X direction. One of the pair of first lines to be cut 15a is set so as to overlap with the intended observation location K when viewed from the Z direction. The pair of second lines to be cut 15b is set so as to be spaced apart from (not overlap with) the intended observation location K when viewed from the Z direction.

[0042] The spacing between the pair of first planned cutting lines 15a and the spacing between the pair of second planned cutting lines 15b correspond to the size of the observation chip TP (see FIG. 12(b)) obtained in the subsequent cutting process. The spacing between the pair of first planned cutting lines 15a and the spacing between the pair of second planned cutting lines 15b are set so that the observation chip TP is of a size that can be input into an analysis device in the subsequent process of observing the planned observation location. The multiple planned cutting lines 15 do not have to pass between each of the multiple functional elements included in the functional element layer 23 when viewed from the Z direction.

[0043] As shown in Figures 5 and 6, the object 20, with the retention tape 16 attached to the back surface 20b of the object 20, is placed on the stage 2 with the front surface 20a facing upward. The stage 2 can be moved along the X direction by a first horizontal movement mechanism 8A. The stage 2 can be moved along the Y direction by a second horizontal movement mechanism 8B. The stage 2 is configured to be rotatable about a rotation axis along the Z direction. The stage 2 has a known rotation drive device (not shown) such as a motor, and is driven to rotate about the rotation axis by the driving force of the motor. The rotation of the stage 2 (the operation of the rotation drive device) is controlled by a control unit 9.

[0044] The laser processing head 3 irradiates the object 20 on the stage 2 with a laser beam L that is transparent. The laser processing head 3 focuses the pulsed laser beam L inside the object 20. When the laser beam L is focused inside the object 20 supported on the stage 2, the laser beam L is particularly absorbed in a portion corresponding to the focusing position of the laser beam L (at least a portion of the focusing region), and a modified region 12 is formed inside the object 20.

[0045] The modified region 12 is a region whose density, refractive index, mechanical strength, and other physical properties differ from those of the surrounding unmodified region. Examples of the modified region 12 include a melt-treated region, a crack region, a dielectric breakdown region, and a refractive index change region. The modified region 12 has the property that cracks tend to extend from the modified region 12 to the incident side of the laser light L and to the opposite side. These properties of the modified region 12 are utilized to cut the object 20.

[0046] The alignment cameras 5 and 6 acquire information used for aligning (hereinafter simply referred to as "alignment") the focusing position of the laser light L on the object 20. The alignment cameras 5 and 6 irradiate the object 20 with light and detect the light returning from the object 20 to acquire an image as information used for alignment.

[0047] The internal observation unit 4 observes the inside of the object 20 using transmitted light. The internal observation unit 4 observes the inside of the object 20 by irradiating the object 20 with transmitted light and detecting the transmitted light returning from the object 20. For example, the internal observation unit 4 captures an image of the modified region 12 formed in the object 20 and the tip of a crack extending from the modified region 12. The internal observation unit 4 is connected to the control unit 9. The internal observation unit 4 outputs the captured image (internal image) to the control unit 9. The internal observation unit 4 is not particularly limited, and various known cameras can be used as long as they meet the required performance.

[0048] The first vertical movement mechanism 7A is a mechanism that moves the laser processing head 3 together with the alignment cameras 5 and 6 along the Z direction. The first vertical movement mechanism 7A has a first vertical shaft 71 provided on a columnar first base portion 75. The first base portion 75 is fixed to, for example, an installation surface. The first vertical shaft 71 extends along the Z direction. The mounting portion 39 of the laser processing head 3 is attached to the first vertical shaft 71 so as to be movable along the Z direction. The first vertical movement mechanism 7A moves the laser processing head 3 in the Z direction along the first vertical shaft 71 by the driving force of a drive source (not shown). The first vertical movement mechanism 7A is not particularly limited, and various mechanisms can be used as long as they can move the laser processing head 3 in the Z direction.

[0049] The second vertical movement mechanism 7B is a mechanism that moves the internal observation unit 4 along the Z direction. The second vertical movement mechanism 7B has a second vertical shaft 72 provided on a columnar second base portion 76 fixed to, for example, an installation surface. The second base portion 76 is spaced apart in the X direction from the first base portion 75. The second vertical shaft 72 extends along the Z direction. The mounting portion 49 of the internal observation unit 4 is attached to the second vertical shaft 72 so as to be movable along the Z direction. The second vertical movement mechanism 7B moves the internal observation unit 4 in the Z direction along the second vertical shaft 72 by the driving force of a driving source (not shown). The second vertical movement mechanism 7B is not particularly limited, and various mechanisms can be used as long as they can move the internal observation unit 4 in the Z direction.

[0050] The first horizontal movement mechanism 8A is a mechanism that moves the stage 2 along the X direction. The first horizontal movement mechanism 8A has a first horizontal shaft 81 that is fixed to, for example, an installation surface or the like. The first horizontal shaft 81 extends along the X direction. The stage 2 is attached to the first horizontal shaft 81 via a second horizontal movement mechanism 8B so as to be movable along the X direction. The first horizontal movement mechanism 8A moves the stage 2 and the second horizontal movement mechanism 8B in the X direction along the first horizontal shaft 81 by the driving force of a drive source (not shown). The first horizontal movement mechanism 8A is not particularly limited, and various mechanisms can be used as long as they can move the stage 2 in the X direction.

[0051] The second horizontal movement mechanism 8B is a mechanism that moves the stage 2 along the Y direction. The second horizontal movement mechanism 8B has, for example, a second horizontal shaft 82 that is provided on the first horizontal movement mechanism 8A. The second horizontal shaft 82 extends along the Y direction. The stage 2 is attached to the second horizontal shaft 82 so that it can move along the Y direction. The second horizontal shaft 82 can move along the first horizontal shaft 81 together with the stage 2. The second horizontal movement mechanism 8B moves the stage 2 in the Y direction along the second horizontal shaft 82 by the driving force of a driving source (not shown). The second horizontal movement mechanism 8B is not particularly limited, and various mechanisms can be used as long as they can move the stage 2 in the Y direction.

[0052] The control unit 9 is configured as a computer device including a processor, memory, storage, communication devices, etc. In the control unit 9, the processor executes software (programs) loaded into the memory, etc., and controls reading and writing of data from and to the memory and storage, as well as communication via the communication devices. The control unit 9 controls various operations of the laser processing apparatus 1. The control unit 9 controls operations of the rotation drive device of the stage 2, the laser processing head 3, the alignment cameras 5 and 6, the internal observation unit 4, the first vertical movement mechanism 7A, the second vertical movement mechanism 7B, the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the GUI 10.

[0053] The GUI 10 displays various types of information. The GUI 10 displays the imaging results of the internal observation unit 4 and the imaging results of the alignment cameras 5 and 6. The GUI 10 includes, for example, a touch panel display. Various settings related to processing conditions and the like are input into the GUI 10 by a user's touch or other operation. The device configuration of the laser processing device 1 is not particularly limited and may have various configurations.

[0054] <<Modified Region Forming Process>> In the modified region forming process, the laser processing device 1 described above is used to irradiate the first substrate 21 with laser light L along the planned cutting line 15, with the surface 20a serving as the laser light incident surface, thereby forming multiple rows of modified regions 12 in the Z direction inside the first substrate 21, and propagating cracks from each modified region 12 (modified spot) along the Z direction. The depth position (Z direction position) of each of the multiple rows of modified regions 12 inside the first substrate 21 is not particularly limited. The number of rows of modified regions 12 is not particularly limited, and may be two or more. Of the multiple rows of modified regions 12, the modified region 12a closest to the functional device layer 23 is formed on the functional device layer 23 side of the first substrate 21, specifically, at a position close to the functional device layer 23.

[0055] 6(a), 6(b), and 7(a), when forming the modified region 12a closest to the functional element layer 23 among the multiple rows of modified regions 12 on the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold is irradiated along the ON section (first portion) R1 of the line to cut 15. This forms the modified region 12a along the ON section R1. On the other hand, laser light L is not irradiated along the OFF section (second portion) R2 of the line to cut 15. This prevents the modified region 12a from being formed along the OFF section R2.

[0056] It should be noted that not irradiating the laser light L may be achieved, for example, by stopping the emission of the laser light from the laser processing head 3 or the input of the laser light L to the laser processing head 3, or by blocking the laser light L with a shutter or the like. Instead of not irradiating the laser light L, it may be possible to irradiate laser light L having an energy less than a predetermined threshold value (the same applies hereinafter).

[0057] The OFF section R2 is a portion different from the ON section R1 and corresponds to the planned observation location K of the functional element layer 23. The OFF section R2 is a section that includes the position of the planned observation location K in the extension direction of the line to cut 15. The width of the OFF section R2 is not particularly limited, but is, for example, 1 mm. The width of the OFF section R2 is smaller than the width of the observation tip TP (see Figure 12 (b)) described below. The ON section R1 is a section other than the OFF section R2 on the line to cut 15. The ON section R1 and the OFF section R2 are set based on the results of identifying the planned observation location K in the previous step of identifying the planned observation location. For example, the OFF section R2 may be set so that the planned observation location K is located in its center. For example, the OFF section R2 may be more than twice the longitudinal length of one modified spot. The predetermined threshold corresponds to the minimum energy that allows both the "modified region 12" and the "crack extending from the modified region 12 toward the functional element layer 23" to be formed in the object 20 by irradiation with the laser light L. The predetermined threshold will be described in detail later.

[0058] To form multiple rows of modified regions 12 in the Z direction inside the first substrate 21, specifically, first, the object 20, with the retention tape 16 attached to the back surface 20b of the object 20, is placed on the stage 2 with the front surface 20a facing upward by a robot arm (not shown) and adsorbed. Next, alignment is performed. Specifically, the control unit 9 controls the operation of the first horizontal movement mechanism 8A and the second horizontal movement mechanism 8B based on an image (e.g., an image of the functional element layer 23 of the object 20) acquired by the alignment camera 5 or the alignment camera 6, and moves the stage 2 in the X direction and the Y direction so that the focusing position of the laser light L is aligned with the alignment position.

[0059] Next, the height is set. Specifically, the control unit 9 controls the operation of the first vertical movement mechanism 7A to move the laser processing head 3 along the Z direction so that the focusing position of the laser light L is located on the laser light incident surface. Next, the control unit 9 controls the operation of the first vertical movement mechanism 7A to move the laser processing head 3 along the Z direction so that the focusing position of the laser light L is located in proximity to the functional element layer 23 on the first substrate 21, based on the position at the time of height setting.

[0060] Next, the control unit 9 appropriately controls the operations of the laser processing head 3, the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the rotation drive device of the stage 2, causing the laser processing head 3 to irradiate the object 20 with laser light L and move the stage 2 along the line to cut 15, thereby moving the focusing position of the laser light L relative to the object 20 along the line to cut 15. In this way, a modified region 12a closest to the functional element layer 23 is formed in the first substrate 21 along the line to cut 15.

[0061] 6A, when forming the modified region 12a closest to the functional element layer 23 on the first substrate 21, the laser light L having an energy equal to or greater than a predetermined threshold is irradiated along the ON section R1 of the line to cut 15, while the focusing position of the laser light L is moved along the ON section R1 relative to the target object 20. This forms a plurality of modified spots aligned continuously along the ON section R1, and the modified region 12a is formed in the ON section R1 by these multiple modified spots.

[0062] Next, the stage 2 is moved along the line to be cut 15, and when the focusing position of the laser light L reaches the OFF section R2 of the line to be cut 15, the irradiation of the laser light L from the laser processing head 3 is stopped. In other words, as shown in Figure 6 (b), the laser light L is not irradiated along the OFF section R2 of the line to be cut 15. As a result, multiple modified spots are not formed in the OFF section R2, and modified regions 12a are not formed in the OFF section R2.

[0063] Next, the stage 2 is moved along the line to be cut 15, and when the focusing position of the laser light L reaches the ON section of the line to be cut 15, irradiation of the laser light L from the laser processing head 3 is resumed. That is, as shown in Fig. 7(a) , along the ON section R1 of the line to be cut 15, laser light L having an energy equal to or greater than a predetermined threshold is irradiated, while the focusing position of the laser light L is moved along the ON section R1 relative to the target object 20. In this way, a plurality of modified spots are formed so as to be continuously aligned along the ON section R1, and a modified region 12a is formed in the ON section R1 by these multiple modified spots.

[0064] The portion between the modified regions 12a along the planned cutting line 15 (i.e., the portion where the modified region 12a is not formed) defines (demarcates) a window portion WD. The window portion WD is a portion corresponding to the OFF section R2. In other words, the window portion WD is a portion including the region corresponding to the OFF section R2 between a pair of modified regions 12a, 12a formed along the ON section R1. No modified spots constituting the modified region 12a are formed in the window portion WD. The window portion WD is a portion adjacent to the functional element layer 23 of the first substrate 21, and extends to a range including the position of the planned observation point K in the extension direction of the planned cutting line 15. The window portion WD is a portion not irradiated with the laser light L, or a portion irradiated with the laser light L at an energy level below a predetermined threshold. The window portion WD is a portion where no modified region 12 that could damage the planned observation point K is formed.

[0065] Next, the control unit 9 controls the operation of the first vertical movement mechanism 7A to move the focusing position of the laser light L away from the functional element layer 23. The control unit 9 appropriately controls the operations of the laser processing head 3, the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the rotation drive device of the stage 2 to irradiate the laser light L from the laser processing head 3 onto the object 20 and move the stage 2 along the line 15 to cut, thereby moving the focusing position of the laser light L relative to the object 20 along the line 15 to cut.

[0066] As a result, a plurality of modified spots are formed on the first substrate 21 so as to be continuously aligned along the intended cutting line 15, and these modified spots form modified regions 12 on the first substrate 21. As shown in Figure 7(b) , the formation of the modified regions 12 is carried out again by moving the focusing position of the laser light L away from the functional element layer 23. This is repeated to form some of the multiple rows of modified regions 12 (some of all rows of modified regions 12 ultimately formed on the first substrate 21) inside the first substrate 21.

[0067] Next, as shown in Figure 8(a), the target object 20 is turned upside down. After turning it upside down, the alignment and height setting described above are performed again. At this time, the functional element layer 23 on the first substrate 21 side and the functional element layer 23 on the second substrate 22 side may be different types of devices. In this case, setting information such as chip size, alignment position, position of the intended observation location K, ON period R1, OFF period R2, etc. may be stored separately for laser processing of the first substrate 21 and laser processing of the second substrate 22.

[0068] Using the above-described laser processing device 1, laser light L is irradiated onto the second substrate 22 along the intended cutting line 15 via the holding tape 16, with the back surface 20b serving as the laser light incident surface, thereby forming multiple rows of modified regions 12 in the Z direction inside the second substrate 22, and cracks are propagated from each modified region 12 (modified spot) along the Z direction. The depth position of each of the multiple rows of modified regions 12 inside the second substrate 22 is not particularly limited. The number of rows of modified regions 12 is not particularly limited, and may be two or more. Of the multiple rows of modified regions 12, the modified region 12a closest to the functional device layer 23 is formed on the functional device layer 23 side of the second substrate 22, specifically, formed in a position close to the functional device layer 23.

[0069] 8(b), 9(a), and 9(b), when forming the modified region 12a closest to the functional element layer 23 among the multiple rows of modified regions 12 on the second substrate 22, laser light L having an energy equal to or greater than a predetermined threshold is irradiated along the ON section (third portion) R1 of the line to cut 15. This forms the modified region 12a along the ON section R1. On the other hand, laser light L is not irradiated along the OFF section (fourth portion) R2 of the line to cut 15. This prevents the modified region 12a from being formed along the OFF section R2. The portion between the modified region 12a and the modified region 12a along the line to cut 15 defines a window portion WD.

[0070] Next, the control unit 9 controls the operation of the first vertical movement mechanism 7A to move the focusing position of the laser light L away from the functional element layer 23. The control unit 9 appropriately controls the operations of the laser processing head 3, the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the rotation drive device of the stage 2 to irradiate the laser light L from the laser processing head 3 onto the object 20 and move the stage 2 along the line 15 to cut, thereby moving the focusing position of the laser light L relative to the object 20 along the line 15 to cut.

[0071] As a result, a plurality of modified spots are formed in the second substrate 22 so as to be continuously aligned along the intended cutting line 15, and these modified spots form modified regions 12 in the second substrate 22. The formation of the modified regions 12 is carried out again by moving the focusing position of the laser light L away from the functional element layer 23. This is repeated to form a plurality of rows of modified regions 12 (all of the rows that will ultimately be formed in the second substrate 22) inside the second substrate 22, as shown in FIG.

[0072] Next, as shown in Fig. 10(b), the target object 20 is turned upside down again. After turning it upside down, the above-described alignment and height setting are performed again. As shown in Fig. 11, using the above-described laser processing device 1, laser light L is irradiated onto the first substrate 21 along the planned cutting line 15, with the surface 20a serving as the laser light incident surface, thereby forming modified regions 12 of multiple rows (remaining portions of all rows of modified regions 12 to be ultimately formed on the first substrate 21) inside the first substrate 21.

[0073] <<Internal Observation Process>> In the internal observation process, the inside of the object 20 is observed using the laser processing device 1 described above. In the internal observation process, the presence or absence of modified spots (dents) is confirmed in the regions of the first substrate 21 and the second substrate 22 irradiated with laser light L at an energy equal to or greater than a predetermined threshold (i.e., the modified regions 12a). The observation of the modified spots may be performed by direct observation. In the internal observation process, the presence or absence of cracks is confirmed in the window portions WD of the first substrate 21 and the second substrate 22 (i.e., the regions irradiated with laser light L at an energy below a predetermined threshold or not irradiated with laser light L). The cracks to be observed are cracks extending in the thickness direction. The cracks to be observed are cracks extending from the edges of the modified spots. The cracks may also be observed by back surface reflection observation.

[0074] As an example, in the internal observation process, the control unit 9 controls the operation of the rotation drive device of the stage 2, the first horizontal movement mechanism 8A, and the second horizontal movement mechanism 8B to move the stage 2 so that the object 20 is positioned at a position for internal observation by the internal observation unit 4. The internal observation unit 4 acquires multiple internal images. Here, for example, the second vertical movement mechanism 7B moves the internal observation unit 4 along the Z direction at at least one location in the ON section R1 and at least one location in the OFF section R2 of the planned cutting line 15, and images of the object 20 are captured by aligning the focusing position of the transmitted light at multiple positions inside the object 20, thereby acquiring multiple internal images as image data. The control unit 9 determines the presence or absence of cracks and modified spots based on the acquired image data.

[0075] In the internal observation step, the following judgment and processing may be performed based on the results of the internal observation: That is, if it is confirmed that there is a modified spot in the region irradiated with laser light L at an energy equal to or greater than a predetermined threshold (the region corresponding to the ON section R1) and that there is a crack in the window portion WD (the region corresponding to the OFF section R2), it is judged that the modified region formation step has been properly performed and that the product is a good product.

[0076] If it is confirmed that there are no modified spots in the area irradiated with laser light L at an energy level equal to or greater than a predetermined threshold and that there are cracks in the window portion WD, the product is determined to be defective because the modified area formation process was not performed properly. In this case, the processing conditions may be changed to change the formation position of the modified area 12a in the Z direction, or additional processing may be performed to form the modified area 12a by changing the formation position in the Z direction, or the processing conditions may be changed to increase the number of rows forming the modified area 12a, or additional processing may be performed to increase the number of rows forming the modified area 12a.

[0077] If a modified spot is confirmed in the region irradiated with laser light L at an energy level equal to or greater than a predetermined threshold and no cracks are confirmed in the window portion WD, the product is determined to be defective and the modified region formation process was not performed properly. In this case, the processing conditions may be changed to narrow the width of the OFF section R2, additional processing may be performed to narrow the width of the OFF section R2, processing conditions such as the focusing position in the Z direction in laser processing along the ON section R1, output, and focusing correction amount may be changed, or additional processing may be performed to change the focusing position in the Z direction in laser processing along the ON section R1, output, and focusing correction amount.

[0078] If it is confirmed that there are no modified spots in the area irradiated with laser light L at an energy level equal to or greater than a predetermined threshold, and that there are no cracks in the window portion WD, the product is determined to be defective because the modified region formation process was not performed properly. In this case, the processing conditions may be changed to change the formation position of the modified region 12a in the Z direction, or additional processing may be performed to change the formation position in the Z direction to form the modified region 12a. The processing conditions may be changed to increase the number of rows forming the modified region 12a, or additional processing may be performed to increase the number of rows forming the modified region 12a. Furthermore, the processing conditions may be changed to narrow the width of the OFF section R2, or additional processing may be performed to narrow the width of the OFF section R2. Processing conditions such as the Z-direction focusing position, output, and focusing correction amount during laser processing along the ON section R1 may be changed, or additional processing may be performed to change the Z-direction focusing position, output, and focusing correction amount during laser processing along the ON section R1.

[0079] Furthermore, in the internal observation process, the formation position of the modified region 12a and the position and distance of the window portion WD are detected based on the results of the internal observation. If, in a plan view, the formation position of the modified region 12a is deviated from the planned observation point K in a direction perpendicular to the extension direction of the line to cut 15, the processing conditions of the modified region 12a may be corrected. If at least one of the position and dimensions of the window portion WD is not appropriate for the planned observation point K, at least one of the position and dimensions of the window portion WD may be adjusted.

[0080] In addition, if the internal image obtained by internal observation includes both the window portion WD and the area other than the window portion WD, the internal image may be used to judge both the window portion WD and the area other than the window portion WD. The presence or absence of modified spots may also be checked in the window portion WD. If modified spots are confirmed in the window portion WD, the product may be judged to be defective. In this case, since the positions of the ON section R1 and the OFF section R2 may be misaligned, the settings of the positions of the ON section R1 and the OFF section R2 may be adjusted. Furthermore, the internal observation process may be performed after the modified region formation process or during the modified region formation process.

[0081] <Cutting Process> In the cutting process, after the modified region forming process, the object 20 is cut along the planned cutting line 15. In the cutting process, stress is applied to the object 20 by, for example, roller breaking, to extend the crack extending from the modified region 12 along the Z direction, and the object 20 is cut along the planned cutting line 15 (see FIG. 12( a)). In this way, the observation chip TP shown in FIG. 12( b) is obtained.

[0082] The observation chip TP is a chip obtained by cutting the object 20 along the planned cutting line 15, and includes a first substrate 21, a functional device layer 23, and a second substrate 22. The first substrate 21, the functional device layer 23, and the second substrate 22 are stacked in this order. The observation chip TP has an observation surface 29, which is the cut surface. A planned observation location K is exposed in the functional device layer 23 of the observation surface 29. In the example shown, the planned observation location K is exposed at the center of the functional device layer 23 of the observation surface 29. Multiple rows of modified regions 12 are exposed in the first substrate 21 and the second substrate 22 of the observation surface 29. The multiple rows of modified regions 12 are aligned along the stacking direction in which the first substrate 21, the functional device layer 23, and the second substrate 22 are stacked. The modified region 12a closest to the functional device layer 23 on the observation surface 29 has a window portion WD. On the observation surface 29, the intended observation location K is disposed so as to be sandwiched between the pair of window portions WD in the stacking direction.

[0083] The cutting method in the cutting step is not particularly limited. For example, in the cutting step, the target object 20 may be cut along the cut line 15 by tape expanding, expanding breaking, mechanical breaking, or the like.

[0084] <Planned Observation Area Observation Process> In the planned observation area observation process, the planned observation area K of the functional element layer 23 of the observation chip TP is observed using an analytical device such as an SEM, TEM, or EPMA. In the planned observation area observation process, when an SEM is used as an example, the observation chip TP is first placed on a sample moving stage in the sample chamber with the observation surface 29 facing upward. At this time, to prevent charging of the observation surface 29, increase the amount of secondary electrons generated, and obtain a clear image signal, the observation surface 29 may be thinly and uniformly coated with metal particles by sputtering or vapor deposition as a pretreatment. The air in the sample chamber is evacuated and the sample chamber is evacuated. Then, the planned observation area K of the observation chip TP is searched for at a low magnification, and the magnification is gradually increased to display and photograph an enlarged image of the planned observation area K. At this time, the position of the planned observation area K is identified based on the window portion WD of the observation surface 29, and the planned observation area K is observed.

[0085] As described above, in the object processing method of this embodiment, when forming the modified region 12a closest to the functional device layer 23 on the first substrate 21, the energy of the irradiated laser light L is set to a predetermined threshold value or higher along the ON section R1 of the line to cut 15. This ensures that the modified region 12a closest to the functional device layer 23 is formed, and allows a crack to extend from the modified region 12a to the functional device layer 23. On the other hand, when forming the modified region 12a on the first substrate 21, the laser light L is not irradiated along the OFF section R2 corresponding to the planned observation location K of the line to cut 15. This prevents the modified region 12a, which could damage the planned observation location K, from being formed too close to the planned observation location K, thereby preventing damage to the planned observation location K. This makes it possible to observe the functional device layer 23 with good accuracy.

[0086] In the modified region forming step of the object processing method of this embodiment, when forming the modified region 12a closest to the functional device layer 23 on the first substrate 21, pulsed laser light L is irradiated along the ON section R1, but laser light is not irradiated along the OFF section R2. In this case, it is possible to reliably prevent the modified region 12a from being formed along the OFF section R2.

[0087] The object processing method of this embodiment includes a planned observation location specifying step of specifying a planned observation location K of the functional device layer 23. In the modified region forming step, an ON section R1 and an OFF section R2 are set based on the results of the specified observation location specifying step. In this case, the ON section R1 and the OFF section R2 can be set using the results of the specified observation location specifying step.

[0088] The object processing method of this embodiment includes a cutting step of cutting the object 20 along the planned cutting line 15 after the modified region forming step, and a planned observation location observing step of observing the planned observation location K after the cutting step. In this case, in the planned observation location observing step, in the observation chip TP, which is the object 20 after cutting, a window portion WD (i.e., a portion where no modified region 12 that could damage the planned observation location K is formed) is close to the planned observation location K, so by referring to the window portion WD, the planned observation location K can be observed with high positional accuracy.

[0089] In the object processing method of this embodiment, in the modified region forming step, a plurality of rows of modified regions 12 are formed in the Z direction inside the second substrate 22 by irradiating the second substrate 22 with laser light L along the line to cut 15. When forming the modified region 12a in the second substrate 22 closest to the functional device layer 23, laser light L having an energy equal to or greater than a predetermined threshold is irradiated along the ON section R1 of the line to cut 15, and laser light L is not irradiated along the OFF section R2 of the line to cut 15. In this case, it is possible to easily cut the object 20 by utilizing cracks extending from the modified region 12a formed in the second substrate 22, while suppressing the formation of modified regions 12a in the second substrate 22 that could damage the intended observation location K in the second substrate 22 close to the intended observation location K.

[0090] In the object processing method of this embodiment, in the modified region forming step, a plurality of rows of partial modified regions 12 are formed inside the first substrate 21 by irradiating the first substrate 21 with laser light L along the planned cutting line 15. A plurality of rows of modified regions 12 are formed inside the second substrate 22 by irradiating the second substrate 22 with laser light L along the planned cutting line 15. Thereafter, a plurality of rows of other modified regions 12 are formed inside the first substrate 21 by irradiating the first substrate 21 with laser light L. This makes it possible to suppress processing effects such as warping that occur in the object 20 due to the formation of the modified regions 12 when laser processing is performed to form a plurality of rows of modified regions 12 in the first substrate 21 and the second substrate 22.

[0091] The object processing method of this embodiment includes an internal observation step of observing the inside of the object 20. In the internal observation step, the modified region 12a of the first substrate 21 is observed for the presence or absence of modified spots, and the window portion WD of the first substrate 21 is observed for the presence or absence of cracks. In this case, by observing the inside of the object 20, it can be confirmed whether the laser processing has been properly performed on the first substrate 21.

[0092] In the object processing method of this embodiment, the predetermined threshold corresponds to the minimum energy at which the modified region 12a and a crack extending from the modified region 12a toward the functional element layer 23 can be formed by irradiation with the laser light L. In this case, the modified region 12a is reliably formed along the ON section R1, and the formation of the modified region 12 that could damage the intended observation location K can be reliably prevented along the OFF section R2.

[0093] In the object processing method of this embodiment, when viewed from the Z direction, the planned cutting line 15 is set so as to overlap with the planned observation location K. In this case, the planned observation location K is exposed on the observation surface 29 of the observation tip TP, which is the object 20 after cutting, and therefore the planned observation location K can be easily observed.

[0094] FIG. 13 is a photograph showing the window portion WD of the object 20. As shown in FIG. 13 , according to this embodiment, it can be seen that the window portion WD is formed in the modified region 12a closest to the functional device layer 23. It can also be seen that the straightness of cracks in the functional device layer 23 is enhanced. As shown in the figure, the end of the modified region 12a on the functional device layer 23 side may be close to or in contact with the functional device layer 23. The distance between the end of the modified region 12a on the functional device layer 23 side and the functional device layer 23 is equal to or less than the Z-direction dimension (vertical length) of the modified region 12a. This allows the window portion WD to be filled with cracks. The Z-direction dimension of the modified region 12a may be any of the mean, median, mode, minimum, and maximum values. The distance between the end of the modified region 12a on the functional device layer 23 side and the functional device layer 23 may be, for example, approximately 30 μm or less.

[0095] In the modified area formation process of this embodiment, a laser processing device 1 is used for laser processing both the first substrate 21 and the second substrate 22, but this is not limited to this, and a laser processing device that is optimal for laser processing the first substrate 21 may be used, and a laser processing device that is optimal for laser processing the second substrate 22 may also be used.

[0096] In the planned observation location observing step of this embodiment, the planned observation location K is observed based on the window portion WD. In this case, the planned observation location K can be easily identified, for example, even at low magnification, by referring to the window portion WD. Observing the planned observation location K based on the window portion WD in this manner is particularly effective when observing the planned observation location K by SEM observation, etc.

[0097] In this embodiment, the width of the OFF section R2 is not particularly limited. By shortening the OFF section R2, the window portion WD becomes easier to break and the cutting quality of the window portion WD is improved. On the other hand, by lengthening the OFF section R2, even if there is an error in the coordinate position of the planned observation location K, the position of the planned observation location K can be reliably included in the OFF section R2 in the direction along the planned cutting line 15. This can also be used when there are multiple planned observation locations K.

[0098] Second Embodiment Next, a second embodiment will be described, focusing on differences from the first embodiment.

[0099] The object processing method of this embodiment differs from the first embodiment in the processing order in the modified region forming step. That is, in the modified region forming step, a first substrate 21 is irradiated with laser light L along the planned cutting line 15 to form multiple rows of modified regions 12 inside the first substrate 21, and a second substrate 22 is irradiated with laser light L along the planned cutting line 15 to form multiple rows of modified regions 12 inside the second substrate 22.

[0100] 14(a), laser light L is applied to the first substrate 21 along the line to be cut 15, with the surface 20a serving as the laser light incident surface, to form multiple rows of modified regions 12 in the Z direction inside the first substrate 21, and cracks are propagated from each modified region 12 (modified spot) along the Z direction. When forming the modified region 12a closest to the functional device layer 23 among the multiple rows of modified regions 12 in the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold is applied along the ON section R1 of the line to be cut 15. As a result, the modified region 12a is formed along the ON section R1. On the other hand, laser light L is not applied along the OFF section R2 of the line to be cut 15. As a result, the modified region 12a is not formed along the OFF section R2.

[0101] Next, as shown in FIG. 14B , the object 20 is turned upside down. Laser light L is irradiated onto the second substrate 22 along the planned cutting line 15, with the back surface 20b serving as the laser light incident surface via the holding tape 16, thereby forming multiple rows of modified regions 12 in the Z direction inside the second substrate 22, and cracks are propagated from each modified region 12 (modified spot) along the Z direction. When forming the modified region 12a closest to the functional device layer 23 among the multiple rows of modified regions 12 on the second substrate 22, laser light L with energy equal to or greater than a predetermined threshold is irradiated along the ON section R1 of the planned cutting line 15. This forms the modified region 12a along the ON section R1. On the other hand, laser light L is not irradiated along the OFF section R2 of the planned cutting line 15. This prevents the formation of modified regions 12a along the OFF section R2.

[0102] As described above, in the object processing method of this embodiment, it is possible to increase the straightness of cracks extending in the functional element layer 23, thereby improving the quality of the cut surface of the functional element layer 23, while preventing modified areas 12a that could damage the intended observation location K from being formed close to the intended observation location, thereby preventing damage to the intended observation location K, and enabling good observation of the functional element layer 23.

[0103] In the object processing method of this embodiment, in the modified region forming step, the first substrate 21 is irradiated with laser light L along the planned cutting line 15 to form all of the multiple rows of modified regions 12 inside the first substrate 21, and the second substrate 22 is irradiated with laser light L to form all of the multiple rows of modified regions 12 inside the second substrate 22. As a result, when performing laser processing to form multiple rows of modified regions 12 on the first substrate 21 and the second substrate 22, it is possible to reduce the frequency of flipping the object 20, for example, and shorten the processing time.

[0104] Third Embodiment Next, a third embodiment will be described, focusing on differences from the first embodiment.

[0105] In the object 20 of this embodiment, the first substrate 21 is disposed on the holding tape 16 side, and the second substrate 22 is disposed on the first substrate 21 with the functional element layer 23 interposed therebetween. The first substrate 21 is, for example, a wafer with a <100> 45-degree crystal orientation. In this case, the plane perpendicular to the main surface is the (100) plane, and the cleavage direction is a direction intersecting the extension direction of the lines to cut 15. The second substrate 22 is, for example, a wafer with a <100> 0-degree crystal orientation. In this case, the plane perpendicular to the main surface is the (110) plane, and the cleavage direction is a direction along the lines to cut 15. In other words, the inclination angle of the cleavage direction of the first substrate 21 relative to the extension direction of the lines to cut 15 is larger than that of the second substrate 22.

[0106] In the modified region forming process of this embodiment, a row of modified regions 12a is formed inside the second substrate 22 by irradiating the second substrate 22 with laser light L along the planned cutting line 15, and a plurality of rows of modified regions 12 are formed inside the first substrate 21 by irradiating the first substrate 21 with laser light L along the planned cutting line 15. The number of rows of modified regions 12 formed on the first substrate 21 is different from the number of rows of modified regions 12 formed on the second substrate 22, and in this case, is greater than the number of rows of modified regions 12 formed on the second substrate 22.

[0107] 15(a), laser light L is irradiated onto the second substrate 22 along the line to be cut 15, with the surface 20a serving as the laser light incident surface, to form a row of modified regions 12a in positions adjacent to the functional device layer 23 inside the second substrate 22, and cracks are propagated from the modified regions 12a (modified spots) along the Z direction. When forming the modified regions 12a on the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold is irradiated along the ON section R1 of the line to be cut 15. This forms the modified regions 12a along the ON section R1. On the other hand, laser light L is not irradiated along the OFF section R2 of the line to be cut 15. This prevents the formation of modified regions 12a along the OFF section R2.

[0108] Next, as shown in FIG. 15B , the object 20 is turned upside down. Laser light L is irradiated onto the first substrate 21 along the cutting line 15, with the back surface 20b serving as the laser light incident surface via the holding tape 16, thereby forming multiple rows of modified regions 12 in the Z direction within the first substrate 21, and cracks are propagated from each modified region 12 (modified spot) along the Z direction. When forming the modified region 12a closest to the functional device layer 23 among the multiple rows of modified regions 12 on the first substrate 21, laser light L with energy equal to or greater than a predetermined threshold is irradiated along the ON section R1 of the cutting line 15. This forms the modified region 12a along the ON section R1. On the other hand, laser light L is not irradiated along the OFF section R2 of the cutting line 15. This prevents the modified region 12a from being formed along the OFF section R2.

[0109] 15( c), stress is applied to the object 20 from the second substrate 22 side. In other words, stress is applied from one of the first substrate 21 and the second substrate 22, which has fewer rows of modified regions 12 formed thereon. This causes the object 20 to be cut along the line to cut 15.

[0110] As described above, in the object processing method of this embodiment, it is possible to increase the straightness of cracks extending in the functional element layer 23, thereby improving the quality of the cut surface of the functional element layer 23, while preventing modified areas 12a that could damage the intended observation location K from being formed close to the intended observation location, thereby preventing damage to the intended observation location K, and enabling good observation of the functional element layer 23.

[0111] In the object processing method of this embodiment, in the modified region forming step, a row of modified regions 12a is formed inside the second substrate 22 by irradiating the second substrate 22 with laser light L along the planned cutting line 15, and a plurality of rows of modified regions 12 are formed inside the first substrate 21 by irradiating the first substrate 21 with laser light L. This makes it possible to shorten the processing time for laser processing the second substrate 22 when performing laser processing to form modified regions 12 in the first substrate 21 and the second substrate 22.

[0112] In the object processing method of this embodiment, the first substrate 21 has a larger inclination angle of the cleavage direction relative to the extension direction of the line to cut 15 than the second substrate 32. The number of rows of modified regions 12 formed in the first substrate 21 is greater than the number of rows of modified regions 12 formed in the second substrate 22. In this case, the number of rows of modified regions 12 formed in the first substrate 21, where cracks are less likely to propagate along the line to cut 15, is increased, making it possible to reliably cut the first substrate 21.

[0113] The object processing method of this embodiment includes, after the modified region forming step, a cutting step in which stress is applied to the object 20 to cut the object 20 along the line to cut 15. The number of rows of modified regions 12 formed in the first substrate 21 is different from the number of rows of modified regions 12 formed in the second substrate 22. In the cutting step, stress is applied from one of the first substrate 21 and the second substrate 22, which has fewer rows of modified regions 12 formed. In this case, it is possible to reliably cut the object 20 along the line to cut 15.

[0114] In this embodiment, the inclination angle of the cleavage direction of the first substrate 21 relative to the planned cutting line 15 is larger than the inclination angle of the cleavage direction of the second substrate 22 relative to the planned cutting line 15, but instead of or in addition to this, the thickness of the first substrate 21 may be made thicker than that of the second substrate 22.

[0115] In this embodiment, one or more other modified regions adjacent to the modified region 12a may be further formed inside the second substrate 22 by irradiating the second substrate 22 with laser light L along the line to cut 15. When further forming other modified regions adjacent to the modified region 12a in the second substrate 22, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section (seventh portion) R1, and laser light L not irradiated or laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section (eighth portion) R2. In this case, the object 20 can be more easily cut (easily cracked) than when a single row of modified regions 12a is formed inside the second substrate 22.

[0116] Fourth Embodiment Next, a fourth embodiment will be described, focusing on differences from the first embodiment.

[0117] The first substrate 21 is, for example, a wafer with a <100> 45-degree crystal orientation, in which case the plane perpendicular to the main surface is the (100) plane, and the cleavage direction is a direction intersecting the extension direction of the lines to cut 15. The second substrate 22 is, for example, a wafer with a <100> 0-degree crystal orientation, in which the plane perpendicular to the main surface is the (110) plane, and the cleavage direction is a direction along the lines to cut 15. In other words, the inclination angle of the cleavage direction of the first substrate 21 with respect to the extension direction of the lines to cut 15 is larger than that of the second substrate 22. The first substrate 21 is, for example, a silicon substrate.

[0118] In the modified region forming process of this embodiment, modified regions 12 are formed only within the first substrate 21. Specifically, as shown in FIG. 16( a), laser light L is irradiated onto the first substrate 21 along the line to cut 15, with the surface 20a serving as the laser light incident surface, to form multiple rows of modified regions 12 in the Z direction within the first substrate 21, and cracks are propagated from each modified region 12 (modified spot) along the Z direction. When forming the modified region 12a closest to the functional device layer 23 among the multiple rows of modified regions 12 in the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold is irradiated along the ON section R1 of the line to cut 15. This forms modified regions 12a along the ON section R1. On the other hand, laser light L is not irradiated along the OFF section R2 of the line to cut 15. This prevents modified regions 12a from being formed along the OFF section R2.

[0119] 16(b), in the cutting process of this embodiment, stress is applied to the object 20 from the second substrate 22 side. In other words, stress is applied from one side of the first substrate 21 or the second substrate 22 where the modified region 12 is not formed. In this way, the object 20 is cut along the line to cut 15.

[0120] As described above, in the object processing method of this embodiment, it is possible to increase the straightness of cracks extending in the functional element layer 23, thereby improving the quality of the cut surface of the functional element layer 23, while preventing modified areas 12a that could damage the intended observation location K from being formed close to the intended observation location, thereby preventing damage to the intended observation location K, and enabling good observation of the functional element layer 23.

[0121] In the object processing method of this embodiment, the modified region forming step forms the modified region 12 only inside the first substrate 21. This eliminates the need for laser processing to form the modified region 12 in the second substrate 22, thereby shortening the processing time.

[0122] The object processing method of this embodiment includes a cutting step, which applies stress to the object 20 after the modified region forming step, to cut the object 20 along the line to cut 15. In the cutting step, stress is applied from the second substrate 22 side. In this case, it is possible to reliably cut the object 20 along the line to cut 15.

[0123] If the materials of the first substrate 21 and the second substrate 22 are different, the laser processing device needs to be configured to be able to irradiate laser light L of wavelengths corresponding to the first substrate 21 and the second substrate 22, which may result in a complicated configuration. In this case, in this embodiment, the modified region 12 is formed only in the first substrate 21, so it is sufficient to be able to irradiate laser light L of a wavelength corresponding to the first substrate 21, and the configuration of the laser processing device 1 can be simplified.

[0124] Fifth Embodiment Next, a fifth embodiment will be described, focusing on differences from the first embodiment.

[0125] 17(a), one of the pair of first lines to cut 15a is set to overlap the intended observation location K when viewed from the Z direction. One of the pair of second lines to cut 15b is set to overlap the intended observation location K when viewed from the Z direction. By cutting the object 20 on which such lines to cut 15 are set along the lines to cut 15 in the modified region forming step and the cutting step, the observation chip TP shown in FIG.

[0126] In this embodiment, along the ON section R1 of the first line to cut 15a, laser light L having energy equal to or greater than a predetermined threshold is irradiated, and along the OFF section R2 of the first line to cut 15a, laser light L having energy less than the predetermined threshold is irradiated or no laser light L is irradiated. Furthermore, along the ON section R1 of the second line to cut 15b, laser light L having energy equal to or greater than a predetermined threshold is irradiated, and along the OFF section R2 of the second line to cut 15b, laser light L having energy less than the predetermined threshold is irradiated or no laser light L is irradiated.

[0127] In the observation chip TP, a planned observation location K is exposed in the functional device layer 23 at a corner between the observation surface 29a, which is a cut surface, and the observation surface 29b, which is another cut surface. In each of the observation surfaces 29a and 29b, the modified region 12a closest to the functional device layer 23 has a window portion WD. In each of the observation surfaces 29a and 29b, the planned observation location K is positioned so as to be sandwiched between the pair of window portions WD.

[0128] As described above, in the object processing method of this embodiment, it is possible to increase the straightness of cracks extending in the functional element layer 23, thereby improving the quality of the cut surface of the functional element layer 23, while preventing modified areas 12a that could damage the intended observation location K from being formed close to the intended observation location K, thereby preventing damage to the intended observation location K, and enabling good observation of the functional element layer 23.

[0129] In the object processing method of this embodiment, the intended observation location K is exposed at a corner of the observation tip TP, which is the object 20 after cutting, and therefore it becomes possible to easily observe the intended observation location K. It becomes possible to observe the intended observation location K three-dimensionally from two sides.

[0130] Sixth Embodiment Next, a sixth embodiment will be described, focusing on differences from the first embodiment.

[0131] In this embodiment, as shown in FIG. 18( a), the lines to cut 15 are set so as to be spaced apart from the intended observation location K when viewed from the Z direction. A pair of first lines to cut 15a are set so that the intended observation location K is located therebetween when viewed from the Z direction. A pair of second lines to cut 15b are set so that the intended observation location K is located therebetween when viewed from the Z direction. For example, one of the pair of first lines to cut 15a is set so as to be offset by 10 μm in the Y direction from the intended observation location K when viewed from the Z direction. By cutting the object 20 on which such lines to cut 15 are set along the lines to cut 15 in the modified region forming process and the cutting process, the observation chip TP shown in FIG. 18( b) is obtained.

[0132] In the observation chip TP, the planned observation location K is not exposed. In the observation chip TP, the planned observation location K can be observed in a completely non-destructive state, and for example, transmission observation can be performed using X-rays or the like from the observation surface 29, which is the cut surface. In this case, in order to make it easier to observe the planned observation location K, pre-observation processing such as FIB and etching may be performed to remove the side of the observation chip TP opposite to the observation surface 29 side of the planned observation location K, and a groove portion 27 may be formed in the observation chip TP.

[0133] As described above, in the object processing method of this embodiment, it is possible to increase the straightness of cracks extending in the functional element layer 23, thereby improving the quality of the cut surface of the functional element layer 23, while preventing modified areas 12a that could damage the intended observation location K from being formed close to the intended observation location K, thereby preventing damage to the intended observation location K, and enabling good observation of the functional element layer 23.

[0134] In the object processing method of this embodiment, when viewed from the Z direction, the planned cutting line 15 is set to be separated from the planned observation location K. In this case, for example, it becomes possible to perform transmission observation of the planned observation location K from the cut surface of the object 20 after cutting.

[0135] In this embodiment, observation may be performed while finely digging from the cut surface of the observation chip TP to the intended observation location K using, for example, an FIB device, a laser milling device, a polishing device, or the like. That is, the object processing method of this embodiment may include, after the cutting step, a planned observation location observation step in which the intended observation location K of the functional element layer 23 is observed while removing the object 20 from the cut surface toward the intended observation location K. In this case, the observation accuracy can be further improved. Also, for example, three-dimensional observation of the intended observation location K becomes possible.

[0136] [Modifications] As described above, one aspect of the present disclosure is not limited to the above embodiment.

[0137] In the above embodiment, when identifying the planned observation location K in the planned observation location identifying step, the planned observation location K may be marked. The marking may be performed using a material that prevents the laser light L from converging onto the planned observation location K so that the modified region 12 is not formed in the OFF section. For example, the marking may be performed using a material that prevents the energy of the laser light L that passes through the marked area from exceeding a predetermined threshold. In this case, in the modified area forming step, for example, after performing laser processing that separates the ON section and the OFF section, the marked area is removed and laser processing is performed that does not separate the ON section and the OFF section.

[0138] In the above embodiment, after the planned observation area specifying process is completed, the modified area forming process may be performed after the following singulation process. In the singulation process, the target object 20 may be cut into small pieces that include the planned observation area K and are larger than the observation chip TP, thereby reducing the size. By reducing the size, the size of the stage 2 of the laser processing device 1 used in the modified area forming process can be reduced, thereby reducing the device size and cost. The method of cutting into small pieces in the singulation process may be a method using blade dicing, a diamond cutter, or the like. When such a singulation process is included, the planned cutting line 15 in the modified area forming process may be a single strip line that passes through the planned observation area K (or is shifted by about 10 μm), and does not necessarily have to be a grid-like line.

[0139] In the above embodiment, among the processing conditions for forming the modified region 12, the thickness of the object 20 may be measured before forming the modified region 12 in order to determine the depth position (Z-direction position) at which the modified region 12 is formed in the object 20. This is because if the thickness of the object 20 is thinner than expected, the modified region 12 may be formed in the window portion WD, and if the thickness of the object 20 is thicker than expected, it may not be possible to cut it properly. Various known methods can be used to measure the thickness of the object 20.

[0140] In the above embodiment, in the internal observation step, transmitted light as observation light may be reflected at the bonding surface of the object 20 (the surface where the functional element layer 23 on the first substrate 21 side and the functional element layer 23 on the second substrate 22 side are bonded together), and the reflected transmitted light may be used to detect the tip of a crack extending from the modified region 12 and determine the state of the crack. As a configuration and method for determining the state of such a crack, for example, the configuration and method disclosed in JP 2022-116996 A may be used.

[0141] In the modified region forming step of the above embodiment, when forming the modified region 12a closest to the functional element layer 23 in the first substrate 21 and / or the second substrate 22, pulsed laser light L may be irradiated along both the ON section R1 and the OFF section R2 of the line to cut 15. Specifically, when forming the modified region 12a in the first substrate 21 and / or the second substrate 22, pulsed laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R1, and pulsed laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R2. In this case, the output of the laser light L can be stabilized.

[0142] In the above embodiment, in the modified region forming step, when the modified region 12 a closest to the functional device layer 23 is formed in the first substrate 21 and / or the second substrate 22, pulsed laser light L may be irradiated along the ON section R1 of the line to cut 15, and continuous laser light L may be irradiated along the OFF section R2. Specifically, when the modified region 12 a is formed in the first substrate 21 and / or the second substrate 22, pulsed laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R1, and continuous laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R2. In this case, when the modified region 12 a closest to the functional device layer 23 is formed in the first substrate 21 along the line to cut 15, it is possible to reliably prevent the modified region 12 from being formed along the OFF section R2.

[0143] In the above embodiment, another functional element layer may be formed on the main surface of the first substrate 21 opposite to the second substrate 22. Another functional element layer may be formed on the main surface of the second substrate 22 opposite to the first substrate 21.

[0144] 19(a), when forming the modified region (other modified region) 12b adjacent to the modified region 12a closest to the functional element layer 23 among the multiple rows of modified regions 12 on the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section (fifth portion) R1, and laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section (sixth portion) R2. The portion between the modified regions 12a, 12b and the modified regions 12a, 12b along the planned cutting line 15 (i.e., the portion where the modified regions 12a, 12b are not formed) defines the window portion WD. Even in this case, it is possible to improve the straightness of the cracks extending in the functional element layer 23, thereby improving the quality of the cut surface of the functional element layer 23, while further preventing the formation of modified areas 12a, 12b that could damage the intended observation point K from being close to the intended observation point K, thereby further preventing damage to the intended observation point K.

[0145] 19(a), when forming the modified region 12c adjacent to the modified region 12b on the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R1, and laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R2 (see FIG. 19(b)). The portion between the modified regions 12a, 12b, 12c and the modified regions 12a, 12b, 12c along the planned cutting line 15 (i.e., the portion where the modified regions 12a, 12b, 12c are not formed) defines a window portion WD.

[0146] In this case, it is possible to further prevent modified regions that may damage the intended observation location K from being formed close to the intended observation location K, and further prevent damage to the intended observation location K. As shown in the figure, modified regions 12a and 12b may be formed so as to overlap each other. Modified regions 12b and 12c may be formed so as to overlap each other. In this case, the divisibility of the functional element layer 23 is improved, and even an object 20 including a thicker functional element layer 23 can be cut.

[0147] In the above embodiment, as shown in FIG. 20( a), when forming the modified region 12b adjacent to the modified region 12a closest to the functional device layer 23 among the multiple rows of modified regions 12 on the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R11, and laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R12. The portion between the modified regions 12a, 12b and the modified regions 12a, 12b (i.e., the portion where the modified regions 12a, 12b are not formed) defines a window portion WD. The ON section R11 is offset from the ON section R1 and partially coincides with the ON section R1. The OFF section R12 is offset from the OFF section R2 and partially coincides with the OFF section R2.

[0148] This modified example corresponds to a case where a delay occurs in the rising edge of the pulse of the laser light L with respect to the ON sections R1, R11 and the OFF sections R2, R12. Therefore, it is not necessary to correct the delay in the rising edge of the pulse of the laser light L.

[0149] 20(b), when forming on the first substrate 21 the modified region 12b adjacent to the modified region 12a closest to the functional element layer 23 among the multiple rows of modified regions 12, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R11, and no laser light L or laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R12. When forming on the first substrate 21 the modified region 12c adjacent to the modified region 12b among the multiple rows of modified regions 12, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R21, and no laser light L or laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R22. When forming a modified region 12d adjacent to a modified region 12c among multiple rows of modified regions 12 on a first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R31, and laser light L may not be irradiated or laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R32.

[0150] The modified regions 12a-12d and the portions between the modified regions 12a-12d (i.e., the portions where the modified regions 12a-12d are not formed) define a window portion WD. The OFF section R12 is wider than the OFF section R2 and includes the OFF section R2. The OFF section R22 is wider than the OFF section R12 and includes the OFF section R12. The OFF section R32 is wider than the OFF section R22 and includes the OFF section R22. In this manner, the shape of the window portion WD may be designed to have a unique design. By narrowing the OFF section R2 in the modified region 12a closer to the functional device layer 23, cutting performance can be improved. By widening the OFF section R32 in the modified region 12d farther from the functional device layer 23, the intended observation region K can be easily identified even at low magnification by referring to the window portion WD in the subsequent intended observation region observation process.

[0151] The shape of the window portion WD shown in FIG. 20( b) (an inverted triangular shape convex toward the functional device layer 23) is advantageous in terms of leakage of the laser light L. That is, since the positions of the modified regions 12a to 12d are further away from the functional device layer 23 in this order, the irradiation range of the leakage light of the laser light L on the functional device layer 23 becomes larger (the energy density decreases), and therefore, there is a possibility that the leakage light will hit the intended observation location K. Therefore, the shape of the window portion WD shown in FIG. 20( b) is advantageous in terms of damage prevention. Note that when the shape of the window portion WD is a triangle convex toward the opposite side to the functional device layer 23, it leads to improved cutting force.

[0152] 21(a), when there are multiple planned observation locations K, the OFF sections R2 corresponding to the respective observation locations K may be set on the planned cutting line 15 to form the modified region 12a closest to the functional device layer 23 and the modified region 12b adjacent to the modified region 12a. In this case, cuttability can be ensured.

[0153] 21(b), when there are multiple planned observation locations K, one OFF section R2 corresponding to the multiple planned observation locations K may be set on the planned cutting line 15 to form the modified region 12a closest to the functional element layer 23 and the modified region 12b adjacent to the modified region 12a. In this case, it is possible to reduce the number of times that laser processing is switched between the ON section R1 and the OFF section R2.

[0154] In the above embodiment, as shown in Figure 22 (a), when forming a modified region 12 that is not adjacent to the functional element layer 23 along the intended cutting line 15, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R1, and laser light L may not be irradiated or laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R2.

[0155] In the above embodiment, as shown in Figure 22 (b), when forming the modified region 12a closest to the functional element layer 23 and the adjacent modified region 12b on the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R1, and laser light L may not be irradiated or laser light L having an energy less than the predetermined threshold may be irradiated not only along the OFF section R2 but also along the OFF section R3.

[0156] In the above embodiment, as shown in Figure 22 (c), when forming all modified regions 12 on the first substrate 21, laser light L having an energy equal to or greater than a predetermined threshold may be irradiated along the ON section R1, and laser light L may not be irradiated or laser light L having an energy less than the predetermined threshold may be irradiated along the OFF section R2.

[0157] 23 , when forming the modified region 12a closest to the functional element layer 23 on the first substrate 21, the first substrate 21 may be irradiated with laser light L having energy below a predetermined threshold along the OFF section R2 to form a modified spot 12s that is smaller than the modified spot formed along the ON section R1. Even if the modified spot 12s is formed, high-quality observation of the intended observation section K is possible as long as the intended observation section K is not damaged and can be cut with good quality.

[0158] That is, the energy equal to or greater than a predetermined threshold may be energy capable of cutting the object 20 (e.g., 5 μJ or greater), energy capable of forming a modified spot with a crack (e.g., energy at which it is possible to confirm by internal observation that the tip of the crack is closer to the functional element layer 23 than the modified spot), or energy capable of forming a modified region 12 with a dimension in the thickness direction of 12 μm or greater. The energy less than the predetermined threshold may be less than 5 μJ, energy capable of forming a modified region 12 consisting of only modified spots without cracks, energy capable of forming modified regions 12 with cracks extending from some modified spots but not toward the functional element layer 23, energy capable of forming only modified regions 12 with a dimension in the thickness direction of less than 12 μm, or energy of laser light L once reflected by the functional element layer 23.

[0159] In the above embodiment, the first, third, fifth, and seventh portions of the line to cut 15 are all set to the ON section R1, but the first, third, fifth, and seventh portions may be different from one another or may at least partially overlap. In the above embodiment, the second, fourth, sixth, and eighth portions of the line to cut 15 are all set to the OFF section R2, but the second, fourth, sixth, and eighth portions may be different from one another or may at least partially overlap.

[0160] The laser processing apparatus 1 of the above embodiment may be provided with a function for specifying the planned observation location K, and for example, the planned observation location K may be specified using the laser processing apparatus 100 shown in FIG. 24 . In this case, the planned observation location specifying step can be performed using the laser processing apparatus 100. The apparatus for performing laser processing and the apparatus for specifying the planned observation location K can be integrated, and alignment information of the object 20, position information of the planned observation location K, etc. can be shared. In addition, for example, the step of marking after specifying the planned observation location K can be eliminated. The laser processing apparatus 100 will be described in detail below.

[0161] The laser processing apparatus 100 includes an analysis unit 110, a laser processing head 120, an object placement unit 130, and a control unit 140. The analysis unit 110 identifies a fault location at a planned observation location K of the object 20. The laser processing head 120 focuses laser light L inside the object 20. The laser processing head 120 corresponds to the laser processing head 3 (see FIG. 5). The object 20 is placed in the object placement unit 130. The control unit 140 controls various operations of the laser processing apparatus 100. The control unit 140 corresponds to the control unit 9 (see FIG. 5). The laser processing apparatus 100 may be, for example, an inverted emission microscope having the laser processing head 120.

[0162] The analysis section 110 has a tester unit 111, a light source 112, an observation optical system 113, an XYZ stage 114, and a two-dimensional camera 115. The tester unit 111 is electrically connected to the object 20. The tester unit 111 applies a stimulus signal specified by the control section 140 to the object 20. The tester unit 111 repeatedly applies a stimulus signal such as a predetermined test pattern to the object 20.

[0163] The light source 112 outputs light to the object 20. The light output from the light source 112 passes through the object 20. The light output from the light source 112 is provided to the observation optical system 113. The observation optical system 113 outputs the light output from the light source 112 to the object 20. The observation optical system 113 has an objective lens 113a and a beam splitter 113b. The objective lens 113a focuses the light on an observation area. The observation optical system 113 guides the light reflected from the object 20 to the two-dimensional camera 115. The observation optical system 113 guides the luminescence generated in the object 20 in response to the application of a stimulus signal to the two-dimensional camera 115.

[0164] The observation optical system 113 is placed on an XYZ stage 114. The XYZ stage 114 is movable in the X, Y, and Z directions. The XYZ stage 114 is controlled by the control unit 140. The observation area is determined by the position of the XYZ stage 114. The observation optical system 113 guides reflected light from the object 20 in response to the irradiated light to the two-dimensional camera 115 as light from the object 20.

[0165] The two-dimensional camera 115 receives light from the object 20. The two-dimensional camera 115 receives emission light generated in response to a stimulus signal. The two-dimensional camera 115 outputs image data for generating an emission image to the control unit 140 based on the received light. The emission image makes it possible to identify the emission point in the object 20. By identifying the emission point, it is possible to identify the intended observation point K of the object 20. A camera equipped with a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor may be used as the two-dimensional camera 115.

[0166] The laser processing head 120 has a laser light source 121, a laser optical system 122, an XYZ stage 123, a probing camera 124, and an illumination light source 125. The laser processing head 120 irradiates the object 20 with laser light output by the laser light source 121 via the laser optical system 122. The laser light source 121 outputs laser light to be irradiated onto the object 20. The laser optical system 122 has an objective lens 122a and a switching unit 122b. The switching unit 122b switches the optical paths of the laser light source 121 and the probing camera 124. The objective lens 122a focuses the laser light. The objective lens 122a guides light coming from the surface of the object 20 to the probing camera 124.

[0167] The laser optical system 122 is placed on an XYZ stage 123. The Z-axis direction of the XYZ stage 123 is the optical axis direction of the objective lens 122a. The XYZ stage 123 moves the laser optical system 122 in the Z direction. The XYZ stage 123 moves the laser optical system 122 in the X and Y directions. The probing camera 124 captures an image of the object 20. The probing camera 124 outputs the captured image to the control unit 140. A user can understand the processing status of the object 20 by checking the captured image. The illumination light source 125 illuminates the object 20 with illumination light when capturing an image with the probing camera 124.

[0168] The object placement unit 130 holds the object 20. The object placement unit 130 changes the position of the object 20 relative to the observation optical system 113 and the laser optical system 122. The object placement unit 130 has a sample stage 131, a wafer chuck 132, and an XY drive unit 133. The wafer chuck 132 is slidably placed on the sample stage 131. The wafer chuck 132 has a holder 132a that holds the object 20. The XY drive unit 133 moves the wafer chuck 132 in the X direction or the Y direction.

[0169] The control unit 140 is physically configured to include memories such as RAM and ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. Examples of the control unit 140 include a personal computer, a cloud server, and a smart device (smartphone, tablet terminal, etc.). The control unit 140 functions by executing a program stored in the memory with the CPU of the computer system.

[0170] The control unit 140 controls the XYZ stage 114 of the analysis unit 110 so that the planned observation location K falls within the field of view of the two-dimensional camera 115. The control unit 140 controls the XYZ stage 123 of the laser processing head 120 so that the optical axis of the observation optical system 113 coincides with the optical axis of the laser optical system 122. The control unit 140 controls the laser light source 121. The control unit 140 is electrically connected to the two-dimensional camera 115. The control unit 140 uses the image data input from the two-dimensional camera 115 to create a pattern image based on reflected light from the object 20 and an emission image based on emission from the object 20.

[0171] The control unit 140 generates a superimposed image as an analysis image by superimposing the pattern image and the luminescent image. The control unit 140 outputs the analysis image to the display unit 141d. The display unit 141d is a display device such as a display for showing the analysis image, etc. to the user. The user inputs information indicating the planned observation location K using the input unit 141e. The input unit 141e is an input device such as a keyboard and mouse that accepts input from the user.

[0172] The components in the above-described embodiment and modified examples are not limited to the materials and shapes described above, and various materials and shapes can be applied. Furthermore, the components in the above-described embodiment and modified examples can be arbitrarily applied to the components in other embodiments or modified examples.

[0173] 12...modified area, 12a...modified area, 12b...modified area (other modified area), 12c...modified area, 12d...modified area, 15...planned cutting line, 20...object, 21...first substrate, 22...second substrate, 23...functional element layer, K...planned observation area, L...laser light, R1, R11, R21, R31...ON section (first part, third part, fifth part), R2, R12, R22, R32...OFF section (second part, fourth part, sixth part).

Claims

1. A method for processing an object including a first substrate and a second substrate stacked on the first substrate with a functional element layer interposed therebetween, the method comprising: a modified region forming step of forming multiple rows of modified regions in the thickness direction inside the first substrate by irradiating the first substrate with laser light along a planned cutting line; in the modified region forming step, when forming the modified region closest to the functional element layer among the multiple rows of modified regions in the first substrate, the laser light having an energy equal to or greater than a predetermined threshold is irradiated along a first portion of the planned cutting line, and the laser light having an energy less than the predetermined threshold is irradiated along a second portion different from the first portion of the planned cutting line and corresponding to the planned observation location of the functional element layer, or the laser light is not irradiated.

2. The object processing method of claim 1, wherein in the modified area forming process, when forming the modified area closest to the functional element layer among the multiple rows of modified areas on the first substrate, the pulsed laser light is irradiated along the first portion, and the laser light is not irradiated along the second portion.

3. The object processing method of claim 1, wherein in the modified area forming process, when forming the modified area closest to the functional element layer among the multiple rows of modified areas on the first substrate, the pulsed laser light is irradiated along the first portion and the second portion.

4. The object processing method of claim 1, wherein in the modified area forming process, when forming the modified area closest to the functional element layer among the multiple rows of modified areas on the first substrate, the pulsed laser light is irradiated along the first portion, and the continuous laser light is irradiated along the second portion.

5. A method for processing an object according to any one of claims 1 to 4, further comprising a step of specifying a planned observation location of the functional element layer before the modified area formation step, wherein the first portion and the second portion are set in the modified area formation step based on the results of the step of specifying a planned observation location.

6. A method for processing an object according to any one of claims 1 to 5, comprising: a cutting step of cutting the object along the planned cutting line after the modified area forming step; and a planned observation point observation step of observing the planned observation point of the functional element layer after the cutting step.

7. An object processing method as described in claim 6, wherein in the step of observing the intended observation area, the intended observation area of ​​the functional element layer is observed based on a window portion including an area corresponding to the second portion between a pair of modified areas formed along the first portion.

8. A method for processing an object described in any one of claims 1 to 7, wherein in the modified region forming step, the laser light is irradiated onto the second substrate along the planned cutting line, thereby forming one row or multiple rows of the modified regions in the thickness direction inside the second substrate, and when forming on the second substrate the modified region of the one row or multiple rows that is closest to the functional element layer, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a third part of the planned cutting line, and the laser light having an energy less than the predetermined threshold is irradiated or the laser light is not irradiated along a fourth part different from the third part of the planned cutting line and corresponding to the planned observation location of the functional element layer.

9. The object processing method of claim 8, wherein the modified area forming step includes: irradiating the laser light onto the first substrate along the planned cutting line to form some of the modified areas in multiple rows inside the first substrate; irradiating the laser light onto the second substrate along the planned cutting line to form some of the modified areas in multiple rows inside the second substrate; and irradiating the laser light onto the first substrate along the planned cutting line to form other of the modified areas in multiple rows inside the first substrate.

10. The object processing method of claim 8, wherein in the modified area forming process, the laser light is irradiated onto the first substrate along the planned cutting line to form multiple rows of the modified areas inside the first substrate, and the laser light is irradiated onto the second substrate along the planned cutting line to form multiple rows of the modified areas inside the second substrate.

11. The object processing method of claim 8, wherein in the modified area forming process, the laser light is irradiated onto the second substrate along the planned cutting line to form one row of the modified areas inside the second substrate, and the laser light is irradiated onto the first substrate along the planned cutting line to form multiple rows of the modified areas inside the first substrate.

12. A method for processing an object described in any one of claims 8 to 11, wherein the first substrate has a larger inclination angle of the cleavage direction relative to the extension direction of the line to cut than the second substrate and / or is thicker than the second substrate, and the number of rows of the modified regions formed on the first substrate is greater than the number of rows of the modified regions formed on the second substrate.

13. A method for processing an object according to any one of claims 8 to 12, further comprising, after the modified area forming step, a cutting step of applying stress to the object to cut the object along the planned cutting line, wherein the number of rows of the modified areas formed on the first substrate is different from the number of rows of the modified areas formed on the second substrate, and wherein in the cutting step, the stress is applied from one side of the first substrate or the second substrate on which fewer rows of the modified areas are formed.

14. The object processing method according to any one of claims 1 to 7, wherein in the modified region forming step, the modified region is formed only inside the first substrate.

15. An object processing method as described in claim 14, further comprising a cutting step of cutting the object along the intended cutting line by applying stress to the object after the modified area forming step, wherein the stress is applied from the second substrate side in the cutting step.

16. A method for processing an object according to any one of claims 1 to 15, further comprising an internal observation step of observing the inside of the object, wherein in the internal observation step, the presence or absence of modified spots is observed for areas of the first substrate that have been irradiated with laser light having an energy equal to or greater than the predetermined threshold, and the presence or absence of cracks is confirmed for areas of the first substrate that have been irradiated with laser light having an energy less than the predetermined threshold or that have not been irradiated with laser light.

17. A method for processing an object described in any one of claims 1 to 16, wherein the predetermined threshold corresponds to the minimum energy at which the laser light irradiation can form the modified region and a crack extending from the modified region toward the functional element layer.

18. A method for processing an object described in any one of claims 1 to 17, wherein, when viewed in the thickness direction of the object, the planned cutting line is set to overlap the planned observation location of the functional element layer.

19. A method for processing an object according to any one of claims 1 to 18, wherein, when the object is viewed in the thickness direction, the intended cutting line is set so as to be spaced apart from the intended observation location of the functional element layer.

20. A method for processing an object as described in claim 19, comprising: a cutting step of cutting the object along the planned cutting line after the modified area forming step; and a planned observation point observation step of observing the planned observation point of the functional element layer while removing the object from the cut surface toward the planned observation point after the cutting step.

21. A method for processing an object described in any one of claims 1 to 20, wherein in the modified region forming step, when forming on the first substrate another modified region adjacent to the modified region closest to the functional element layer among the multiple rows of modified regions, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a fifth portion of the planned cutting line, and the laser light having an energy less than the predetermined threshold or the laser light is not irradiated along a sixth portion different from the fifth portion of the planned cutting line and corresponding to the planned observation location of the functional element layer, and at least a part of the sixth portion overlaps with the second portion.

22. In the modified region forming step, the laser light is irradiated onto the second substrate along the line to be cut, thereby forming a plurality of rows of the modified regions in the thickness direction inside the second substrate; when forming on the second substrate the modified region closest to the functional device layer among the plurality of rows of the modified regions, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a third portion of the line to be cut, and the laser light having an energy less than the predetermined threshold is irradiated or no laser light is irradiated along a fourth portion different from the third portion of the line to be cut and corresponding to the intended observation location of the functional device layer; when forming on the second substrate another modified region adjacent to the modified region closest to the functional device layer among the plurality of rows of the modified regions, the laser light having an energy equal to or greater than the predetermined threshold is irradiated along a seventh portion of the line to be cut, and the laser light having an energy less than the predetermined threshold is irradiated or no laser light is irradiated along an eighth portion different from the seventh portion of the line to be cut and corresponding to the intended observation location of the functional device layer; The method for processing an object according to claim 1 , wherein at least a part of the eighth portion overlaps with the fourth portion.

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