Bonded substrate grinding method, grinding apparatus, and processing apparatus

Abstract

To provide a grinding method of a laminated substrate capable of quickly determining whether or not a peeling part exists in the laminated substrate.SOLUTION: The method for grinding a bonded substrate stack includes a grinding step of grinding a first substrate of the bonded substrate stack including the first substrate and a second substrate bonded to the first substrate, and a determining step of determining, after the grinding step is performed, whether or not the bonded substrate stack includes a peeled portion where part of the first substrate is peeled from the second substrate, wherein the grinding step and the determining step are performed by the same apparatus.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for grinding a bonded substrate, which grinds a first substrate included in a bonded substrate, a grinding device capable of grinding a first substrate included in a bonded substrate, and a processing device capable of forming a modified region inside a first substrate included in a bonded substrate and then grinding the first substrate. [Background technology]

[0002] Chips for devices such as integrated circuits (ICs) or memories are generally manufactured using a disk-shaped substrate made of semiconductor material such as silicon (Si). Specifically, chips are manufactured by forming multiple devices on the surface of the substrate and then dividing the substrate along the boundaries between the multiple devices.

[0003] Furthermore, for the purpose of achieving high integration, a chip may be manufactured from a bonded substrate including multiple substrates in which devices provided on each substrate are electrically connected via through-silicon vias (TSVs) (see, for example, Patent Document 1). This bonded substrate is manufactured, for example, in the following order.

[0004] First, a recess is formed on the front surface of a first substrate. Then, TSVs are provided in the recess. Next, the front surface of the first substrate is bonded to a second substrate. Next, the back surface of the first substrate is ground until the TSVs are exposed on the back surface of the first substrate. Next, the front surface of a third substrate is bonded to the back surface of the first substrate. As a result, a bonded substrate is produced, including first to third substrates, in which devices provided on each of the first and third substrates are electrically connected via the TSVs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-57709 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, if the bonding between the first substrate and the second substrate is partially insufficient when manufacturing a bonded substrate, a part of the first substrate may peel off from the second substrate as the first substrate is ground. If the front side of the third substrate is bonded to the back side of the first substrate despite the existence of such a peeled portion (peeled portion), not only the bonded substrate including the first substrate and the second substrate but also the third substrate may have to be discarded.

[0007] In view of this, an object of the present invention is to provide a method, a grinding apparatus and a processing apparatus for grinding a bonded substrate, which are capable of quickly determining whether or not a peeled portion exists in the bonded substrate. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a grinding method for a bonded substrate, the method comprising: a grinding step of grinding a first substrate of a bonded substrate including a first substrate and a second substrate bonded to the first substrate; and a determining step of determining, after the grinding step has been performed, whether or not a peeled portion where a part of the first substrate has peeled from the second substrate is present in the bonded substrate, wherein the grinding step and the determining step are performed using the same apparatus.

[0009] In the determining step, it is preferable to determine whether or not the peeled portion exists in the bonded substrate using a thickness measuring device for measuring the thickness of an arbitrary position on the bonded substrate or the first substrate, or to determine whether or not each of the plural positions is the peeled portion based on a change in intensity of reflected light caused by projecting measurement light from the first substrate side toward the plural positions included in the bonded substrate in order.

[0010] Furthermore, when the thickness measuring device is used to determine whether or not the peeled portion exists on the bonded substrate, the determining step preferably determines whether or not each of the plurality of positions is the peeled portion based on the thickness of the first substrate calculated from each of a plurality of spectral spectra obtained by spectroscopically analyzing reflected light generated by projecting measurement light from the thickness measuring device sequentially from the first substrate side toward a plurality of positions included in the bonded substrate. Alternatively, in this case, the determining step preferably determines whether or not each of the plurality of positions is the peeled portion based on the amplitude of an amplitude spectrum obtained by fast Fourier transforming each of a plurality of spectral spectra obtained by spectroscopically analyzing reflected light generated by projecting measurement light from the thickness measuring device sequentially from the first substrate side toward a plurality of positions included in the bonded substrate. Alternatively, in this case, the determining step preferably determines whether or not each of the plurality of positions is the peeled portion based on a fitting coefficient obtained when calculating the thickness of the first substrate by fitting each of a plurality of spectral spectra obtained by spectroscopically analyzing reflected light generated by projecting measurement light from the thickness measuring device sequentially from the first substrate side toward a plurality of positions included in the bonded substrate to a simulation spectrum.

[0011] Furthermore, in the determination step, it is preferable to determine that the bonded substrate is defective when the ratio or number of peeled portions in the bonded substrate exceeds a threshold value.

[0012] In addition, the grinding method for a bonded substrate of the present invention preferably further comprises, after the determining step, a display step of displaying an image including the bonded substrate in which the peeled portion and the portion other than the peeled portion are distinguished. Furthermore, the grinding method for a bonded substrate of the present invention preferably further comprises, before the grinding step, a holding step of holding the bonded substrate on a holding table so that the first substrate is exposed, and the grinding step and the determining step are each performed while the bonded substrate is held on the holding table. In this case, the grinding method for a bonded substrate of the present invention preferably further comprises, before the holding step, a modified region forming step of irradiating the first substrate with a laser beam along the outer edge of the first substrate to form an annular modified region within the first substrate, and the determining step preferably determines whether the peeled portion is present in the bonded substrate and whether a portion of the first substrate outside the modified region has been removed.

[0013] According to another aspect of the present invention, there is provided a grinding apparatus comprising: a holding table for holding a bonded substrate including a first substrate and a second substrate bonded to the first substrate; a rotation mechanism for rotating the holding table; a grinding unit for grinding the bonded substrate; an inspection unit for inspecting the bonded substrate; and a controller for controlling the rotation mechanism, the grinding unit, and the inspection unit, wherein the controller controls the grinding unit to grind the first substrate while controlling the rotation mechanism to rotate the holding table that holds the bonded substrate with the first substrate exposed, and then has a processor for controlling the inspection unit to detect data used in determining whether or not a peeled portion, where a portion of the first substrate has peeled off from the second substrate, is present in the bonded substrate.

[0014] Preferably, the inspection unit includes a thickness gauge for measuring the thickness of the bonded substrate or the first substrate at any position, and the processor controls the inspection unit to detect, as the data, the thickness of the bonded substrate or the first substrate at each of a plurality of positions included in the bonded substrate. Alternatively, the inspection unit preferably includes a light-projecting unit for projecting measurement light and a light-receiving unit for receiving reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate, and the processor controls the inspection unit to detect, as the data, a change in intensity of the reflected light received by the light-receiving unit as a result of the light-projecting unit sequentially projecting the measurement light toward a plurality of positions included in the bonded substrate.

[0015] Furthermore, when the inspection unit includes the thickness measuring device, the thickness measuring device is a non-contact thickness measuring device including a light-projecting unit for projecting measurement light, a spectroscopic unit for spectrally dividing reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate, and a light-receiving unit for receiving the reflected light spectrally divided by the spectroscopic unit, and the processor preferably controls the inspection unit to detect, as the data, the thickness of the first substrate calculated from each of a plurality of spectral spectra obtained by projecting the measurement light from the light-projecting unit sequentially toward a plurality of positions included in the bonded substrate, the reflected light being spectrally divided by the spectroscopic unit, and then being received by the light-receiving unit. Alternatively, in this case, the thickness measuring instrument is a non-contact thickness measuring instrument including a light-projecting unit for projecting measurement light, a spectroscopic unit for spectrally separating reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate, and a light-receiving unit for receiving the reflected light spectrally separated by the spectroscopic unit, and the processor preferably controls the inspection unit to detect, as the data, the amplitude of an amplitude spectrum obtained by fast Fourier transform of each of a plurality of spectral spectra obtained by projecting the measurement light from the light-projecting unit sequentially toward a plurality of positions included in the bonded substrate, the reflected light generated by the light-projecting unit being spectrally separated by the spectroscopic unit, and then receiving the spectrally separated light by the light-receiving unit. Alternatively, in this case, the thickness measuring instrument is a non-contact thickness measuring instrument including a light-projecting unit for projecting measurement light, a spectroscopic unit for spectrally separating reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate, and a light-receiving unit for receiving the reflected light spectrally separated by the spectroscopic unit, and the processor preferably controls the inspection unit to detect as the data a fitting rate obtained when fitting each of a plurality of spectral spectra obtained by projecting the measurement light from the light-projecting unit sequentially toward a plurality of positions included in the bonded substrate, to a simulation spectrum to calculate the thickness of the first substrate.

[0016] Furthermore, it is preferable that the controller further has a memory for storing a threshold value for the ratio or number of peeled portions, and that the processor determines that the bonded substrate is defective when the ratio or number of peeled portions in the bonded substrate exceeds the threshold value.It is also preferable that the processor controls the inspection unit to inspect the bonded substrate held by the holding table.

[0017] In addition, it is preferable that the device further comprises a display unit for displaying information about the bonded substrate, and that the processor controls the display unit to display an image including the bonded substrate in which the peeled portion and areas other than the peeled portion are separated after determining whether the peeled portion exists in the bonded substrate.

[0018] According to yet another aspect of the present invention, there is provided a modified region forming section including a first holding table for holding a bonded substrate including a first substrate and a second substrate bonded to the first substrate, and a laser beam irradiation unit for irradiating a laser beam capable of forming a modified region inside the bonded substrate held by the first holding table; a grinding section including a second holding table for holding the bonded substrate, a rotation mechanism for rotating the second holding table, and a grinding unit for grinding the bonded substrate; an inspection section having an inspection unit for inspecting the bonded substrate; and a controller for controlling the laser beam irradiation unit, the rotation mechanism, the grinding unit, and the inspection unit. The controller controls the laser beam application unit to irradiate the laser beam onto the first substrate along the outer edge of the first substrate included in the bonded substrate held on the first holding table with the first substrate exposed, thereby forming an annular modified region inside the first substrate, and then controls the grinding unit to grind the first substrate while controlling the rotation mechanism to rotate the second holding table that holds the bonded substrate with the first substrate exposed, and then has a processor for controlling the inspection unit to detect data used in determining whether or not a peeled portion where a part of the first substrate has peeled off from the second substrate is present in the bonded substrate. [Effects of the Invention]

[0019] In the present invention, a grinding method can be performed, using the same apparatus, to grind the first substrate of a bonded substrate including a first substrate and a second substrate bonded to the first substrate, and to determine whether or not a peeled portion, where a part of the first substrate has peeled off from the second substrate, is present in the bonded substrate. Therefore, in the present invention, it is possible to quickly determine whether or not a peeled portion is present in the bonded substrate. [Brief explanation of the drawings]

[0020] [Figure 1]FIG. 1(A) is a top view that schematically shows an example of a substrate (first substrate), and FIG. 1(B) is a cross-sectional view that schematically shows the substrate shown in FIG. 1(A). [Figure 2] Figure 2(A) is a cross-sectional view that schematically shows how the front surface side of the substrate shown in Figures 1(A) and 1(B) is bonded to the front surface side of a support substrate (second substrate), and Figure 2(B) is a cross-sectional view that schematically shows a bonded substrate produced by the bonding shown in Figure 2(A). [Figure 3] FIG. 3 is a perspective view that schematically shows an example of a grinding apparatus for grinding the bonded substrate shown in FIG. 2(B). [Figure 4] FIG. 4 is a partially cross-sectional side view schematically showing the grinding apparatus shown in FIG. [Figure 5] FIG. 5 is a diagram schematically showing a non-contact type thickness measuring device (inspection unit) provided in the grinding device shown in FIGS. 3 and 4 and components connected to the thickness measuring device. [Figure 6] FIG. 6 is a block diagram that schematically illustrates hardware included in a controller for controlling the components of the grinding apparatus shown in FIGS. [Figure 7] FIG. 7 is a flow chart that schematically shows an example of a method for grinding the bonded substrate shown in FIG. 2(B). [Figure 8] FIG. 8 is a cross-sectional view schematically showing the state of the holding step included in the grinding method for the bonded substrate shown in FIG. [Figure 9] FIG. 9 is a partial cross-sectional side view that schematically shows the state of the grinding step included in the grinding method for the bonded substrate shown in FIG. [Figure 10] FIG. 10 is a top view schematically showing the bonded substrate stack after the grinding step shown in FIG. 9 has been performed. [Figure 11] 11(A) and 11(B) are each a partial cross-sectional side view that schematically shows the state of the determination step included in the grinding method for a bonded substrate shown in FIG. [Figure 12]FIG. 12 is a flow chart schematically showing another example of the method for grinding the bonded substrate shown in FIG. 2(B). [Figure 13] FIG. 13 is a flow chart schematically showing yet another example of the method for grinding the bonded substrate stack shown in FIG. 2(B). [Figure 14] FIG. 14 is a block diagram schematically showing an example of a processing apparatus capable of carrying out the method for grinding a bonded substrate shown in FIG. [Figure 15] FIG. 15 is a diagram schematically illustrating a modified region forming section of the processing apparatus shown in FIG. [Figure 16] Figure 16(A) is a partial cross-sectional side view schematically showing an example of a modified area formation step included in the grinding method for a bonded substrate shown in Figure 13, which is performed in the modified area formation section shown in Figure 15, and Figure 16(B) is a partial cross-sectional side view schematically showing another example of a modified area formation step included in the grinding method for a bonded substrate shown in Figure 13, which is performed in the modified area formation section shown in Figure 15. [Figure 17] Figure 17(A) is a cross-sectional view schematically showing the bonded substrate after the modified area formation step has been performed and then the grinding step has been performed as shown in Figure 16(A), and Figure 17(B) is a cross-sectional view schematically showing the bonded substrate after the modified area formation step has been performed and then the grinding step has been performed as shown in Figure 16(B). DETAILED DESCRIPTION OF THE INVENTION

[0021]

[0023] An embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1(A) is a top view schematically showing an example of a substrate (first substrate), and Fig. 1(B) is a cross-sectional view schematically showing the substrate shown in Fig. 1(A). The substrate 11 shown in Fig. 1(A) and Fig. 1(B) has a front surface 11a and a back surface 11b that are approximately parallel, and is made of, for example, silicon (Si).

[0022] A plurality of devices 13 are provided on the surface 11a side of the substrate 11. Each device 13 includes, for example, a semiconductor element for constituting an IC, a semiconductor memory, or a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The plurality of devices 13 are arranged in a matrix. That is, the boundaries between the plurality of devices 13 extend in a lattice pattern.

[0023] Furthermore, a recessed portion in which wiring such as a through-silicon via (TSV (Through-Silicon Via)) is provided may be formed in the substrate 11. The outer periphery of the substrate 11 is chamfered. In other words, the side surface 11c of the substrate 11 is curved so as to be convex outward.

[0024] There are no limitations on the material, shape, structure, size, etc. of substrate 11. Substrate 11 may be made of, for example, a semiconductor other than silicon (e.g., silicon carbide (SiC) or gallium nitride (GaN)). Similarly, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of multiple devices 13.

[0025] 2(A) is a cross-sectional view schematically showing how the surface 11a side of the substrate 11 is bonded to the surface 15a side of a support substrate (second substrate) 15, and FIG. 2(B) is a cross-sectional view schematically showing the bonded substrate produced by this bonding. Note that the support substrate 15 bonded to the substrate 11 has, for example, the same shape as the substrate 11. Furthermore, similar to the substrate 11, a plurality of devices may be provided on the surface 15a side of the support substrate 15.

[0026] During this bonding, an adhesive layer 17 containing an acrylic adhesive or an epoxy adhesive is first provided on the surface 15a of the support substrate 15. The adhesive layer 17 is provided, for example, in a disk shape that is concentric with the support substrate 15 in a plan view and has a radius smaller than that of the support substrate.

[0027] Next, while the back surface 15b of the support substrate 15 is supported, the front surface 11a of the substrate 11 is pressed against the front surface 15a of the support substrate 15 via the adhesive layer 17. In this way, a bonded substrate 19 including the substrate 11 and the support substrate 15 bonded to the substrate 11 is produced.

[0028] Fig. 3 is a perspective view schematically showing an example of a grinding apparatus for grinding the bonded substrate 19. Fig. 4 is a partially cross-sectional side view schematically showing the example of the grinding apparatus shown in Fig. 3. Note that the direction indicated by arrow X (X direction) and the direction indicated by arrow Y (Y direction) shown in Figs. 3 and 4 are directions perpendicular to each other on a horizontal plane, and for convenience, the X direction is defined as the backward direction and the Y direction as the leftward direction. The direction indicated by arrow Z (Z direction) is a direction (vertical direction) perpendicular to both the X direction and the Y direction.

[0029] 3 and 4 includes a base 4 that supports each component. A rectangular parallelepiped recess 4a extending along the X direction is formed on the top surface of the base 4. An X-direction movement mechanism 6 is provided inside the recess 4a to move a holding table 28 (described later) along the X direction.

[0030] The X-direction movement mechanism 6 has a pair of guide rails 8 each extending along the X direction. A rectangular parallelepiped X-direction movement plate 10 is attached to the upper sides of the pair of guide rails 8 in a manner that allows it to slide along the X direction. A screw shaft 12 extending along the X direction is disposed between the pair of guide rails 8. A motor 14 for rotating the screw shaft 12 is connected to the rear end of the screw shaft 12.

[0031] A ball screw is formed by providing a nut 16 on the outer circumferential surface of the screw shaft 12, on which the threads are formed, which accommodates a large number of balls that circulate in response to the rotation of the screw shaft 12. The nut 16 is fixed to the lower surface of the X-direction moving plate 10. Therefore, when the screw shaft 12 is rotated by the motor 14, the X-direction moving plate 10 moves in the X direction together with the nut 16.

[0032] A rotation mechanism 18 is provided on the X-direction moving plate 10. This rotation mechanism 18 has a driven pulley 20, a driving pulley (not shown), an endless belt (not shown) wound around the driven pulley 20 and the driving pulley, a rotating body whose lower end is connected to the driven pulley 20, and a motor (not shown) connected to the driving pulley (not shown).

[0033] Furthermore, a tilt adjustment mechanism 22 is provided on the X-direction moving plate 10. This tilt adjustment mechanism 22 has one fixed shaft (not shown) and two movable shafts 24, each of which has a variable length along the Z direction. The fixed shaft and the two movable shafts 24 are connected to the underside of a table base 26 and support the table base 26.

[0034] A through hole (not shown) is formed in the center of table base 26, and a rotating body, the lower end of which is connected to driven pulley 20, passes through this through hole. The upper end of the rotating body is connected to the underside of disk-shaped holding table 28. Table base 26 supports holding table 28 via bearings (not shown).

[0035] When the motor connected to the driving pulley is operated to rotate the endless belt wound around the driven pulley 20, the holding table 28 rotates in the circumferential direction of the holding table 28 without rotating the table base 26. Furthermore, when the lengths of the two movable shafts 24 in the Z direction are adjusted, the inclination of not only the table base 26 but also the holding table 28 is adjusted.

[0036] The holding table 28 has a disk-shaped frame 28a made of ceramics or the like. The frame 28a has a disk-shaped bottom wall and cylindrical side walls extending upright from the bottom wall. A disk-shaped recess defined by the bottom wall and the side walls is formed on the upper surface of the frame 28a. The bottom wall of the frame 28a is formed with a flow path (not shown) that opens at the bottom of the recess, and the flow path communicates with a suction source (not shown) such as an ejector.

[0037] Furthermore, a circular porous plate 28b having a diameter roughly equal to that of a recess formed on the upper surface of frame 28a is fixed to the recess. This porous plate 28b is made of, for example, porous ceramics. The upper surface of porous plate 28b and the upper surface of the side wall of frame 28a have a shape corresponding to the side of a cone (a shape in which the center protrudes beyond the outer periphery).

[0038] When a suction source communicating with a flow path formed inside frame 28a is operated, a suction force acts on the space near the upper surface of porous plate 28b. Therefore, by operating the suction source with bonded substrate stack 19 placed on holding table 28, bonded substrate stack 19 can be held by holding table 28.

[0039] Furthermore, a rectangular parallelepiped table cover 30 is provided around the periphery of the holding table 28 so as to surround the holding table 28. The width (length along the Y direction) of this table cover 30 is approximately equal to the width of the recess 4a formed on the upper surface of the base 4. In addition, dustproof and drip-proof covers 32 that are extendable and contractible along the X direction are provided at the front and rear of the table cover 30.

[0040] A square pillar-shaped support structure 34 is provided in an area of ​​the upper surface of the base 4 that is located behind the recess 4a, and a grinding unit 36 ​​is provided in front of this support structure 34. The grinding unit 36 ​​has a Z-direction movement mechanism 38. This Z-direction movement mechanism 38 has a pair of guide rails 40 that each extend along the Z direction.

[0041] A slider 42 is provided on the front side of each of the pair of guide rails 40 so as to be slidable along the Z direction. The front end of the slider 42 is fixed to the rear surface side of a rectangular parallelepiped Z-direction moving plate 44. A screw shaft 46 extending along the Z direction is disposed between the pair of guide rails 40. A motor 48 for rotating the screw shaft 46 is connected to the upper end of the screw shaft 46.

[0042] A nut 50 that houses a large number of balls that circulate in response to the rotation of the screw shaft 46 is provided on the outer circumferential surface on which the screw threads are formed, thereby forming a ball screw. The nut 50 is fixed to the rear surface side of the Z-direction moving plate 44. Therefore, when the screw shaft 46 is rotated by the motor 48, the Z-direction moving plate 44 moves in the Z direction together with the nut 50.

[0043] A cylindrical support member 52 is fixed to the front surface of the Z-direction moving plate 44. A cylindrical spindle housing 54 extending along the Z direction is provided inside the support member 52. A columnar spindle 56 extending along the Z direction is provided inside the spindle housing 54.

[0044] The spindle 56 is rotatably supported by the spindle housing 54, and its upper end (base end) is connected to a motor 58. The spindle 56 also protrudes downward through a through-hole formed in the bottom of the spindle housing 54, and its lower end (tip end) forms a disk-shaped mount 60.

[0045] An annular grinding wheel 62 having an outer diameter roughly equal to the diameter of the mount 60 is attached to the underside of the mount 60 using fixing members (not shown) such as bolts. The grinding wheel 62 has a plurality of grinding stones 62a and a wheel base 62b having a lower surface on which the plurality of grinding stones 62a are arranged discretely in an annular shape. When the motor 58 is operated, the grinding wheel 62 rotates together with the spindle 56 around a rotation axis that is a straight line along the Z direction.

[0046] Each grinding wheel 62a has abrasive grains such as diamond or cBN dispersed in a binder such as a vitrified bond or a resin bond. The wheel base 62b is made of an alloy such as stainless steel or an aluminum alloy.

[0047] A non-contact type thickness measuring device (inspection unit) 64 is provided near the grinding wheel 62. The thickness measuring device 64 includes a measuring head 66, and can detect the thickness of a measurement object such as the bonded substrate stack 19 held on the holding table 28 or the uppermost substrate thereon (for example, substrate 11) (specifically, the thickness of the measurement object at a position directly below the measuring head 66).

[0048] 5 is a diagram schematically illustrating a thickness measuring device 64 and components connected to the thickness measuring device 64. Note that in FIG. 5, some of the components of the thickness measuring device 64 are shown as blocks. The thickness measuring device 64 includes a light projecting unit 68, a spectroscopic unit 70, a light receiving unit 72, and a calculation unit 74.

[0049] The light projecting unit 68 includes a light source such as an SLD (Super Luminescent Diode), an LED (Light Emitting Diode), or an LD (Laser Diode), and projects light (measurement light) such as infrared light generated by the light source from the measurement head 66 directly downward.

[0050] The spectroscopic unit 70 includes a spectrometer such as a diffraction grating or a prism. The spectroscopic unit 70 separates the reflected light generated when the light projecting unit 68 projects the measurement light. Note that this reflected light may include light (interference light) that is the result of interference between light reflected from one of multiple surfaces (e.g., the back surface 11b of the substrate 11) present at the position where the measurement light is projected and light reflected from another surface (e.g., the front surface 11a of the substrate 11).

[0051] The light receiving unit 72 includes an imaging element such as a CCD (Charge Coupled Device) image sensor or a CMOS image sensor. The light receiving unit 72 converts the reflected light dispersed by the spectroscopic unit 70 into an electrical signal indicating the spectrum of the reflected light. If the reflected light contains interference light, interference fringes will appear in the spectrum.

[0052] The calculation unit 74 includes a processor such as a CPU (Central Processing Unit), and calculates the distance between a pair of surfaces present at the position where the measurement light is projected (for example, the distance between the front surface 11a and the back surface 11b of the substrate 11, i.e., the thickness of the substrate 11) based on the spectrum in which the interference fringes appear.

[0053] The calculation unit 74 may identify the distance between the pair of surfaces by using, for example, a fast Fourier transform. Specifically, the calculation unit 74 identifies, as the distance between the pair of surfaces, the distance at which a peak is observed in an amplitude spectrum obtained by performing a fast Fourier transform on the spectroscopic spectrum.

[0054] Alternatively, the calculation unit 74 may identify the distance between the pair of surfaces using a curve fitting method. Specifically, the calculation unit 74 first creates an ideal spectrum (simulation spectrum) through simulation. In this simulation, for example, under an assumed distance between the pair of surfaces, the intensity of the interference light corresponding to each wavelength is calculated while changing the wavelength of the interference light. That is, the calculation unit 74 prepares multiple sets of data, each of which is associated with the wavelength and intensity of the interference light.

[0055] The calculation unit 74 then uses the least squares method to calculate an approximation curve from the multiple sets of data, and sets the resulting curve as a simulation spectrum. Furthermore, the calculation unit 74 repeats the above-described simulation while changing the distance assumed as the spacing between the pair of surfaces. That is, the calculation unit 74 creates multiple simulation spectra, each of which has a different distance assumed as the spacing between the pair of surfaces.

[0056] Once the simulation spectrum is created in this manner, the calculation unit 74 may calculate, for example, the residual sum of squares between the actually measured spectrum and each of the multiple simulation spectra. The calculation unit 74 may then identify the distance assumed as the distance between the pair of surfaces when creating the simulation spectrum that best fits the actually measured spectrum (i.e., has the smallest residual sum of squares) as the distance between the pair of surfaces that are actually present at the position where the measurement light is projected.

[0057] Furthermore, the thickness measuring device 64 may be provided with a liquid supply unit (not shown) for supplying a liquid such as water to the space between the measuring head 66 and the object to be measured. When liquid is supplied from the liquid supply unit when grinding the bonded substrate stack 19 while detecting the thickness of the object to be measured by the thickness measuring device 64, foreign matter (for example, grinding chips generated by grinding) is less likely to enter between the measuring head 66 and the object to be measured.

[0058] In this case, the probability that the measurement light directed from the measurement head 66 to the measurement object and the reflected light from the measurement object directed to the measurement head 66 are blocked by a foreign object is reduced. Therefore, in this case, it is possible to suppress a decrease in the accuracy of the thickness detected by the thickness gauge 64.

[0059] The measuring head 66 is provided at the tip of an arm 76. The arm 76 extends in a direction perpendicular to the Z direction, and its base end is fixed to the upper end of a support shaft 78 that extends in the Z direction. The support shaft 78 is provided so as to protrude from the upper surface of the base 4, and a motor 80 is connected to its lower end.

[0060] When the motor 80 is operated, the support shaft 78 rotates around a straight line along the Z direction as the rotation axis, that is, the thickness gauge 64 rotates around the support shaft 78. This allows the thickness gauge 64 to be positioned at any position within a predetermined range.

[0061] Specifically, by operating the motor 80 and positioning the thickness gauge 64 in a predetermined direction (for example, the direction opposite to the Y direction) as viewed from the support shaft 78, the thickness gauge 64 can be positioned directly above the center in the Y direction of the recess 4a formed in the upper surface of the base 4. By further operating the motor 80 from this state, the thickness gauge 64 can be positioned directly above any position between the center in the Y direction of the recess 4a and the end (right end) on the Y direction side.

[0062] The support shaft 78 and the motor 80 are connected to a Z-direction movement mechanism 82. The Z-direction movement mechanism 82 has a Z-direction movement plate 82a, the front side of which is fixed to the side of the motor 80. A nut 82b that houses a number of balls is fixed to the back side of the Z-direction movement plate 82a.

[0063] A screw shaft 82c extending along the Z direction is screwed into the nut 82b. The screw shaft 82c is provided between a pair of guide rails (not shown) each extending along the Z direction, and a Z-direction moving plate 82a is slidably attached to the surface side of the pair of guide rails.

[0064] A motor 82d is connected to the base end (lower end) of the screw shaft 82c. When the motor 82d rotates the screw shaft 82c, a large number of balls circulate inside the nut 82b, and the Z-direction moving plate 82a, the thickness measuring device 64, etc. move in the Z direction together with the nut 82b.

[0065] Furthermore, the grinding device 2 is provided with a cover (not shown) for covering those of its components that are provided above the base 4. A touch panel 84 is disposed on the front surface of this cover (see FIG. 3). This touch panel 84 is configured with an input unit such as a capacitive or resistive touch sensor and a display unit such as a liquid crystal display or an organic EL (Electro Luminescence) display, and functions as a user interface.

[0066] In addition, the grinding machine 2 includes a controller for controlling its components. Fig. 6 is a block diagram schematically showing the hardware included in this controller. The controller 86 shown in Fig. 6 includes a processor 88 and a memory 90. Furthermore, the memory 90 includes a main memory device 90a with a high rewrite speed and an auxiliary memory device 90b with a large storage capacity.

[0067] The processor 88 includes, for example, a CPU etc. In the grinding device 2, the calculation unit 74 of the thickness measuring device 64 may be incorporated into the processor 88 or may be provided independently of the processor 88.

[0068] The main memory device 90a includes a volatile memory such as a dynamic random access memory (DRAM) or a static random access memory (SRAM), and stores data and other information required for the current calculations of the processor 88.

[0069] This main memory device 90a stores, for example, data (peel determination data) used when determining whether or not a peeled portion where a part of the substrate 11 has peeled off from the support substrate 15 exists in the bonded substrate stack 19. The peel determination data includes the thickness of the measurement object detected by the thickness measuring device 64.

[0070] The peeling determination data may also be data obtained when detecting the thickness. For example, the peeling determination data may be the intensity of reflected light received by the light receiving unit 72 of the thickness measuring device 64. In addition, when the calculation unit 74 calculates the thickness using a fast Fourier transform, the peeling determination data may be the amplitude of the amplitude spectrum obtained by performing a fast Fourier transform on the spectroscopic spectrum, i.e., the intensity of the peak of the amplitude spectrum.

[0071] Furthermore, when the calculation unit 74 calculates this thickness using a curve fitting method, the peeling determination data may be the fitting rate between the spectroscopic spectrum and the simulation spectrum. Note that this fitting rate is calculated, for example, based on the sum of squares of the residuals between the spectroscopic spectrum and the simulation spectrum when the distance between a pair of surfaces that is actually present at the position where the measurement light is projected matches the distance assumed as the distance between the pair of surfaces in the simulation spectrum.

[0072] The auxiliary storage device 90b includes, for example, a nonvolatile memory such as an SSD (Solid State Drive) (NAND flash memory) or an HDD (Hard Disk Drive) (magnetic storage device), etc. The auxiliary storage device 90b stores programs for causing the processor 88 to execute specific processes, data that may be used in the calculations of the processor 88, etc.

[0073] The auxiliary storage device 90b stores, for example, data (defective product determination data) used to determine whether the bonded substrate stack 19 is defective or not. Examples of the defective product determination data include a threshold value for the ratio or number of peeled portions in the bonded substrate stack 19. The peeling determination data may be stored in the auxiliary storage device 90b instead of the main storage device 90a.

[0074] The processor 88 reads out and executes various programs stored in the auxiliary storage device 90b. For example, the processor 88 reads out and executes a program for grinding the bonded substrate stack 19 from the auxiliary storage device 90b.

[0075] 7 is a flow chart showing an example of a grinding method for a bonded substrate in accordance with this program. In this method, first, the bonded substrate 19 is held by a holding table 28 (holding step S1). FIG. 8 is a cross-sectional view showing a typical state of the holding step S1.

[0076] In this holding step S1, first, the processor 88 operates the X-direction movement mechanism 6 to move the holding table 28 forward so as to move the holding table 28 away from the grinding unit 36 ​​and enable the loading of the bonded substrate stack 19. Next, the bonded substrate stack 19 is loaded onto the holding table 28 with the back surface 11b of the substrate 11 facing upward.

[0077] Next, the processor 88 operates the suction source that is connected to the flow path formed inside the frame 28a of the holding table 28. This causes a suction force to act on the rear surface 15b side of the support substrate 15. As a result, the bonded substrate stack 19 is held by the holding table 28 with the substrate 11 exposed.

[0078] After the holding step S1 is performed, the bonded substrate stack 19 is ground (grinding step S2) while being held by the holding table 28. Fig. 9 is a partial cross-sectional side view that schematically shows the state of the grinding step S2.

[0079] In this grinding step S2, first, the processor 88 operates the X-direction movement mechanism 6 to move the holding table 28 backward so that the trajectories of the multiple grinding stones 62a when the grinding wheel 62 is rotated overlap with the center of the holding table 28 in the Z direction. Next, while the processor 88 operates the rotation mechanism 18 and the motor 58 to rotate both the holding table 28 and the grinding wheel 62, the processor 88 operates the motor 48 to lower the grinding wheel 62 until the multiple grinding stones 62a come into contact with the back surface 11b of the substrate 11 (see FIG. 9).

[0080] This starts grinding the back surface 11b side of the substrate 11. In parallel with this grinding, the processor 88 operates the thickness measuring device 64 to detect the thickness of the substrate 11 at a predetermined position. This grinding, i.e., the lowering of the grinding wheel 62 while both the holding table 28 and the grinding wheel 62 are rotating, continues until the thickness of the substrate 11 detected by the thickness measuring device 64 reaches a predetermined thickness. This predetermined thickness is stored in advance in the memory 90 (for example, the auxiliary storage device 90b).

[0081] When the thickness of the substrate 11 detected by the thickness measuring device 64 reaches a predetermined thickness, the processor 88 stops the operation of the rotation mechanism 18 and the motor 58 to stop the rotation of both the holding table 28 and the grinding wheel 62, and also operates the motor 48 to lift the grinding wheel 62. At this time, the processor 88 may store data acquired when the predetermined thickness is detected by the thickness measuring device 64 (specifically, the intensity of the reflected light or the amplitude of the amplitude spectrum, or the fitting rate between the spectroscopic spectrum and the simulation spectrum) in the memory 90 (for example, the main storage device 90a) as peel determination data.

[0082] 10 is a top view schematically showing the bonded substrate 19 after grinding step S2 has been performed. This bonded substrate 19 may include a peeled portion 19a where a part of the substrate 11 has peeled off from the support substrate 15 as a result of grinding the substrate 11 in grinding step S2. Note that at the peeled portion 19a, the adhesive layer 17 remaining on the support substrate 15 side may be exposed, or the adhesive layer 17 may peel off together with the substrate 11, exposing the support substrate 15.

[0083] After the grinding step S2 is performed, it is determined whether or not a peeled portion 19a exists in the bonded substrate stack 19 while the bonded substrate stack 19 is held by the holding table 28 (determination step S3). Figures 11(A) and 11(B) are partial cross-sectional side views each showing a schematic view of the determination step S3.

[0084] In short, in this determination step S3, thickness detection is performed in order for each of a plurality of positions included in the bonded substrate stack 19. For example, in determination step S3, first, the processor 88 operates the X-direction moving mechanism 6 to move the holding table 28 along the X direction and / or operates the motor 80 to rotate the thickness measuring device 64 so that the center of the bonded substrate stack 19 is positioned directly under the measuring head 66 of the thickness measuring device 64.

[0085] Then, while the processor 88 operates the thickness measuring device 64 so as to repeatedly detect the thickness of the measurement object (for example, the substrate 11), the processor 88 operates the rotation mechanism 18 to rotate the holding table 28 little by little, and operates the motor 80 to gradually bring the thickness measuring device 64 closer to the outer periphery of the bonded substrate stack 19 in plan view. In other words, the processor 88 operates the rotation mechanism 18, the motor 80, and the thickness measuring device 64 so that the measurement light is projected sequentially toward a plurality of positions included in the bonded substrate stack 19 and arranged in a spiral shape.

[0086] In this determination step S3, the detection of the thickness at each of the multiple positions included in the bonded substrate stack 19 may be performed in the reverse order. In this case, in determination step S3, first, the processor 88 operates the X-direction moving mechanism 6 to move the holding table 28 along the X direction and / or operates the motor 80 to rotate the thickness measuring device 64 so that a point on the outer periphery of the bonded substrate stack 19 is positioned directly under the measuring head 66 of the thickness measuring device 64.

[0087] Then, while the processor 88 operates the thickness measuring device 64 so that the detection of the thickness of the object to be measured (e.g., the substrate 11) is repeated, the processor 88 operates the rotation mechanism 18 to rotate the holding table 28 little by little, and operates the motor 80 to gradually move the thickness measuring device 64 closer to the center of the bonded substrate 19 in a planar view.

[0088] Furthermore, the bonded substrate stack 19 may be divided into a region where a plurality of positions where thickness measurements are performed are densely packed (dense region) and a region where the positions are dispersed (discrete region). For example, the vicinity of the center of the bonded substrate stack 19 may be set as a dense region, and the vicinity of its periphery may be set as a discrete region. In this case, the processor 88 operates the motor 80 and / or the thickness gauge 64 so that, for example, when the measurement head 66 is located directly above a dense region, the rotation speed of the holding table 28 and / or the frequency of thickness measurements are relatively low, and when the measurement head 66 is located directly above a discrete region, the rotation speed of the holding table 28 and / or the frequency of thickness measurements are relatively high.

[0089] Here, if the position where the thickness is detected is not the peeled portion 19a, reflected light including interference light is generated when light reflected from the back surface 11b of the substrate 11 present at this position interferes with light reflected from the front surface 11a of the substrate 11 (see FIG. 11(A)). Therefore, in this case, the thickness measuring device 64 detects a thickness corresponding to the above-mentioned predetermined thickness, and also detects data corresponding to data acquired when the above-mentioned predetermined thickness is detected (specifically, the intensity of the above-mentioned reflected light or the amplitude of the amplitude spectrum, or the fitting rate between the spectroscopic spectrum and the simulation spectrum).

[0090] On the other hand, when the position where the thickness is measured is the peeled portion 19a, for example, the measurement light is diffused on the surface of the adhesive layer 17, which has become uneven due to the peeling of the substrate 11 (see FIG. 11(B)), or reflected light is generated that includes interference light caused by interference between light reflected on the front surface 15a of the support substrate 15 and light reflected on the back surface 15b of the support substrate 15. Therefore, in this case, it becomes impossible for the thickness measuring device 64 to detect the thickness, or a thickness that does not correspond to the above-mentioned predetermined thickness is detected, and the thickness measuring device 64 detects data that does not correspond to the data acquired when the above-mentioned predetermined thickness is detected.

[0091] Therefore, the processor 88 can determine whether each of the multiple positions is a peeling point 19a by comparing the above-mentioned peeling determination data stored in the memory 90 with each of the multiple pieces of data detected by the thickness measuring device 64 by projecting measurement light sequentially toward multiple positions included in the bonded substrate 19.

[0092] If the processor 88 determines that at least one of the plurality of positions is the peeled portion 19a, it determines that the peeled portion 19a is present in the bonded substrate 19, and if not, it determines that the peeled portion 19a is not present in the bonded substrate 19. Furthermore, the processor 88 may operate the display unit of the touch panel 84 to display a message for notifying the determination result as to whether or not the peeled portion 19a is present in the bonded substrate 19.

[0093] Prior to determining whether each of the plurality of positions where thickness measurement is performed is a peeling site 19a, the processor 88 may operate the display unit of the touch panel 84 to display an image that allows the operator to select data that can be used as peeling determination data (for example, the thickness of the measurement object detected by the thickness measuring device 64, the intensity of reflected light received by the light receiving unit 72 of the thickness measuring device 64, the amplitude of the amplitude spectrum obtained by performing a fast Fourier transform on the spectroscopic spectrum by the calculation unit 74, or the fitting rate obtained when the spectroscopic spectrum is fitted to the simulation spectrum by the calculation unit 74). When the operator touches the touch panel 84 to select data that can be used as peeling determination data, the processor 88 may determine whether each of the plurality of positions is a peeling site 19a based on the selected data.

[0094] In addition, the processor 88 may determine whether the bonded substrate 19 is defective by comparing the above-mentioned defective product determination data stored in the memory 90 (e.g., a threshold value for the proportion or number of peeled areas 19a in the bonded substrate 19) with information regarding the peeled areas 19a (e.g., the proportion or number of peeled areas 19a in the bonded substrate 19).

[0095] For example, the processor 88 may determine that the bonded substrate 19 is defective if the ratio or number of peeled portions 19a exceeds a threshold value, and may otherwise determine that the bonded substrate 19 is non-defective. The processor 88 may also operate the display unit of the touch panel 84 to display a message informing the user of the determination result as to whether the bonded substrate 19 is defective or not.

[0096] 7, the grinding step S2 and the determination step S3 are performed by the same grinding apparatus 2. Therefore, this method makes it possible to quickly determine whether or not a peeled portion 19a exists in the bonded substrate 19.

[0097] It should be noted that the above-described content is one embodiment of the present invention, and the present invention is not limited to the above-described content. For example, the grinding apparatus of the present invention may include components that are not included in the grinding apparatus 2. Examples of such components include at least one of a position adjustment mechanism for aligning the bonded substrate stack 19 before the substrate 11 is ground, and a cleaning unit for cleaning the bonded substrate stack 19 after the substrate 11 is ground.

[0098] The position adjustment mechanism includes, for example, a disk-shaped positioning table whose diameter in a plan view is smaller than that of the bonded substrate stack 19, and a plurality of pins that are arranged around the positioning table and are each movable in the radial direction of the positioning table in a plan view. The position adjustment mechanism can align the center of the bonded substrate stack 19 to a predetermined position by bringing the plurality of pins close to the positioning table with the bonded substrate stack 19 supported on the positioning table.

[0099] The cleaning unit includes, for example, a disk-shaped spinner table that is rotatable in its circumferential direction and capable of holding bonded substrate 19, and a nozzle that is disposed above the spinner table and that supplies a liquid (cleaning liquid) such as water toward the spinner table. In the cleaning unit, bonded substrate 19 can be cleaned by rotating the spinner table while supplying the cleaning liquid from the nozzle with bonded substrate 19 held on the spinner table.

[0100] Furthermore, when the grinding apparatus of the present invention is equipped with at least one of a position adjustment mechanism or a cleaning unit, the determination of whether or not the peeled portion 19a exists in the bonded substrate 19 may be performed with the bonded substrate 19 supported on the positioning table or the spinner table.

[0101] In other words, the determination step performed in the grinding apparatus of the present invention is not limited to the above-mentioned determination step S3, i.e., the step performed while the substrate is held by the holding table 28. However, from the viewpoint of more quickly determining whether or not the peeled portion 19a exists in the bonded substrate stack 19, it is preferable that this determination be performed while the substrate is held by the holding table 28.

[0102] Furthermore, the grinding apparatus of the present invention may be provided with a plurality of thickness gauges 64 arranged in a line. A grinding apparatus provided with a plurality of thickness gauges 64 is preferable in that it can reduce the time required for the above-mentioned determination step S3 compared to the grinding apparatus 2. On the other hand, the grinding apparatus 2 is preferable in that it can be manufactured more inexpensively compared to a grinding apparatus provided with a plurality of thickness gauges 64.

[0103] Furthermore, in the grinding apparatus of the present invention, data detected by a contact-type thickness gauge may be used as the peel determination data, instead of the non-contact-type thickness gauge 64. Furthermore, the peel determination data may be an image formed by capturing an image of the bonded substrate stack 19, or the distance between the measuring head 66 and the bonded substrate stack 19.

[0104] That is, the grinding apparatus of the present invention may be provided with an inspection unit such as a contact-type thickness gauge, a camera, or a distance measuring device instead of or in addition to the non-contact-type thickness gauge 64. In this grinding apparatus, the contact-type thickness gauge, a camera, or a distance measuring device may be used when determining whether or not a peeled portion 19a, where a part of the substrate 11 has peeled off from the support substrate 15, exists in the bonded substrate stack 19.

[0105] Furthermore, in the grinding device of the present invention, a notification unit (for example, a speaker or a pilot lamp) may be provided in addition to the display unit included in the touch panel 84. In this grinding device, the notification unit may be used to notify the determination result of whether or not the bonded substrate stack 19 has a peeled portion 19a and / or the determination result of whether or not the bonded substrate stack 19 is defective.

[0106] Furthermore, when the intensity of the reflected light received by the light-receiving unit 72 of the thickness measuring device 64 is used as data for determining peeling, the reflected light does not need to be spectrally separated. Therefore, in this case, the grinding device of the present invention may be provided with a photodetector capable of projecting measurement light and detecting reflected light, instead of or in addition to the thickness measuring device 64. Then, in this grinding device, when the measurement light is projected sequentially toward a plurality of positions included in the bonded substrate stack 19, it may be determined whether each of the plurality of positions is a peeled portion 19a based on changes in the intensity of the reflected light detected by the photodetector.

[0107] In the above-described determination step S3, the measurement light may be projected sequentially toward a plurality of positions that are included in the bonded substrate stack 19 and that are arranged in a non-spiral pattern. In this case, for example, the processor 88 may operate the X-direction moving mechanism 6, the rotation mechanism 18, the thickness measuring device 64, and the motor 80 as follows.

[0108] First, the processor 88 operates the X-direction moving mechanism 6 to move the holding table 28 along the X direction, and / or operates the motor 80 to rotate the thickness measuring device 64, so that the measuring head 66 is positioned in the X direction when viewed from the center of the bonded substrate 19 in a plan view and does not overlap with the bonded substrate 19.

[0109] Next, while processor 88 operates thickness measuring device 64 to repeatedly detect the thickness of the measurement object (for example, substrate 11), processor 88 operates X-direction moving mechanism 6 to move holding table 28 in the X direction so that the bonded substrate stack 19 passes from one end to the other in the X direction over measurement head 66 in a plan view. As a result, measurement light is projected sequentially toward a plurality of positions that are included in bonded substrate stack 19 and are arranged in a straight line passing through its center, and thickness measuring device 64 detects the thickness of substrate 11 at each position.

[0110] Next, the processor 88 operates the rotation mechanism 18 to rotate the holding table 28, and / or operates the motor 80 to rotate the thickness gauge 64 within a range where the measurement head 66 overlaps with the recess 4a of the base 4 in a plan view. The above-described operations are then repeated. As a result, the thickness of the substrate 11 at each of a plurality of positions included in the bonded substrate stack 19 and arranged in a non-spiral shape can be detected by the thickness gauge 64.

[0111] Furthermore, the grinding method for a bonded substrate of the present invention may include steps that are not included in the grinding method for a bonded substrate shown in Fig. 7. Figures 12 and 13 are each a flowchart schematically showing an example of such a grinding method for a bonded substrate.

[0112] 12, after the above-described holding step S1, grinding step S2, and determination step S3 are performed, an image including the bonded substrate 19 in which the peeled portion 19a and the portion other than the peeled portion 19a are separated is displayed (display step S4). In this display step S4, the processor 88 operates the display unit included in the touch panel 84 to display this image.

[0113] 13, prior to grinding of substrate 11 included in bonded substrate 19, an annular modified region is formed inside substrate 11. Fig. 14 is a block diagram schematically showing an example of a processing apparatus capable of carrying out the grinding method of bonded substrate shown in Fig. 13.

[0114] 14 includes a modified region forming unit 94, a grinding unit 96, an inspection unit 98, and a controller 100 for controlling the components of the modified region forming unit 94, the grinding unit 96, and the inspection unit 98. The grinding unit 96 has the same components as the grinding apparatus 2, except for, for example, the thickness measuring device (inspection unit) 64 and the components connected to the thickness measuring device 64, and the controller 86. The inspection unit 98 has the same components as the thickness measuring device (inspection unit) 64 and the components connected to the thickness measuring device 64. The controller 100 has the same components as the controller 86, for example.

[0115] 15 is a diagram schematically illustrating the modified region forming unit 94. The modified region forming unit 94 includes a holding table (first holding table) 102 having a structure similar to that of the holding table 28, except that its upper surface is generally horizontal. The holding table 102 is connected to a suction source (not shown) having, for example, an ejector or the like, and a rotation mechanism (not shown) having, for example, a pulley, a motor, or the like.

[0116] When the suction source operates, a suction force acts on the space near the upper surface of the holding table 102. Therefore, when the suction source operates with the bonded substrate stack 19 placed on the holding table 102, the bonded substrate stack 19 is held by the holding table 102. When the rotation mechanism operates, the holding table 102 rotates around a rotation axis that passes through the center of the upper surface and is aligned in the vertical direction.

[0117] A laser beam irradiation unit 104 is provided above the holding table 102. The laser beam irradiation unit 104 has a laser oscillator 104a having, for example, Nd:YAG as a laser medium. The laser oscillator 104a emits a laser beam having a wavelength (for example, 1064 nm or 1342 nm) that is transmitted through the material (for example, silicon) of the substrate 11. The output (power) of this laser beam is adjusted by an attenuator 104b, and then supplied to a branching unit 104c.

[0118] The branching unit 104c has a spatial light modulator including a liquid crystal phase control element called LCoS (Liquid Crystal on Silicon) and / or a diffractive optical element (DOE), etc. The branching unit 104c branches the laser beam (original laser beam) whose output has been adjusted in the attenuator 104b, for example, into multiple laser beams that are each focused at different positions.

[0119] The multiple laser beams are reflected by mirror 104d and directed to injection head 104e, which contains a lens (not shown) that focuses each of the multiple laser beams. Each laser beam focused by the lens is then emitted toward holding table 102, or more specifically, directly below.

[0120] The focal point where one of the multiple laser beams is focused and the focal points where the others are focused may, for example, be located at the same position in the horizontal direction but at different positions (heights) in the vertical direction. Alternatively, these focal points may differ not only in height but also in position in the horizontal direction.

[0121] Furthermore, the injection head 104e of the laser beam irradiation unit 104 and an optical system (for example, mirror 104d) for guiding a plurality of laser beams to the injection head 104e are connected to a movement mechanism (not shown) including, for example, a ball screw, etc. When this movement mechanism operates, the injection head 104e etc. move in the horizontal and / or vertical directions.

[0122] In the modified area forming section 94, by operating this moving mechanism, the horizontal and / or vertical position (coordinates) of the focal point where each laser beam emitted from the injection head 104e toward the holding table 102 is focused can be adjusted.

[0123] When performing the grinding method for a bonded substrate shown in Figure 13 in the processing device 92, first, the bonded substrate 19 is held on a holding table (first holding table) 102 provided in the modified area forming section 94 (first holding step S5).

[0124] In this first holding step S5, first, the bonded substrate stack 19 is carried onto the holding table 102 so that the back surface 11b of the substrate 11 faces upward. Next, the suction source connected to the holding table 102 is operated. This causes a suction force to act on the back surface 15b side of the support substrate 15. As a result, the bonded substrate stack 19 is held by the holding table 102 with the substrate 11 exposed.

[0125] After the first holding step S5 is performed, a ring-shaped modified region is formed on the bonded substrate stack 19 while it is held by the holding table 102 (modified region forming step S6). Fig. 16(A) is a partial cross-sectional side view schematically showing an example of the modified region forming step S6 performed in the modified region forming unit 94, and Fig. 16(B) is a partial cross-sectional side view schematically showing another example of the modified region forming step S6 performed in the modified region forming unit 94.

[0126] In the modified region forming step S6, first, the injection head 104e and the like are moved horizontally so that the injection head 104e is positioned directly above an area slightly inside the chamfered outer periphery of the substrate 11. Next, multiple laser beams LB are emitted from the injection head 104e so that each is positioned inside the substrate 11.

[0127] At this time, the multiple laser beams LB are focused to form multiple focusing points that are at the same horizontal position but different vertical positions (heights) (see FIG. 16(A)). In this case, the multiple focusing points are positioned in an annular region outside the multiple devices 13 and adhesive layer 17 provided on the substrate 11 and inside the outer periphery of the substrate 11 in a plan view.

[0128] Alternatively, the multiple laser beams LB may be focused to form multiple focal points that are different in both horizontal and vertical positions (heights) (see FIG. 16(B)). In this case, the multiple focal points are, for example, located inside the outer periphery of the substrate 11 in a planar view, and are arranged so as to be inclined such that the closer to the periphery, the closer to the surface 11a of the substrate 11. In this case, the lowest of the multiple focal points is located in an annular region that is outside the multiple devices 13 and adhesive layer 17 provided on the substrate 11 and inside the outer periphery of the substrate 11 in a planar view.

[0129] In these cases, regions (modified regions) 11d in which the crystalline structure of the material is disrupted are formed inside the substrate 11, each centered on one of the multiple light-focusing points. Furthermore, if the internal stress generated in the substrate 11 due to the formation of multiple modified regions 11d is large, cracks 11e may extend from each modified region 11d. These cracks 11e tend to extend toward adjacent modified regions 11d.

[0130] Next, the holding table 102 is rotated at least once while the multiple laser beams LB are still emitted from the emission head 104e. As a result, an annular modified region 11d is formed inside the substrate 11. Specifically, in the modified region forming step S6 performed as shown in FIG. 16(A), the modified region 11d is formed so as to extend along the side surface of a cylinder. In addition, in the modified region forming step S6 performed as shown in FIG. 16(B), the modified region 11d is formed so as to extend along the side surface of a truncated cone.

[0131] After the modified region forming step S6 is performed, the bonded substrate stack 19 is held by a holding table (second holding table) of the grinding unit 96 (second holding step S1'). Note that the second holding step S1' is performed, for example, in the same manner as the above-described holding step S1.

[0132] After the second holding step S1' is performed, the bonded substrate stack 19 is ground while being held by the second holding table (grinding step S2'). Note that the grinding step S2' is performed in the same manner as the grinding step S2 described above, for example.

[0133] Figure 17(A) is a cross-sectional view schematically showing the bonded substrate 19 after the modified area formation step S6 has been performed and then the grinding step S2' has been performed, as shown in Figure 16(A), and Figure 17(B) is a cross-sectional view schematically showing the bonded substrate 19 after the modified area formation step S6 has been performed and then the grinding step S2' has been performed, as shown in Figure 16(B).

[0134] 17(A) or 17(B), not only is the substrate 11 thinned in the grinding step S2', but cracks 11e also extend from the modified region 11d extending along the side surface of the cylinder or truncated cone. Furthermore, if cracks 11e have already been formed in the modified region forming step S6, the existing cracks 11e further extend. As a result, the portion of the substrate 11 outside the modified region 11d formed therein is removed (so-called edge trimming is performed).

[0135] After the grinding step S2' is performed, while the bonded substrate stack 19 is held by the second holding table, it is determined whether or not the peeled portion 19a is present in the bonded substrate stack 19 and whether or not the portion outside the modified region 11d has been removed (determination step S7). This determination step S7 is performed, for example, in the same manner as the above-mentioned determination step S3.

[0136] Specifically, when the portion outside the modified region 11d remains without being removed, the thickness measuring device 64 detects a thickness corresponding to the above-mentioned specified thickness, and also detects data corresponding to the data obtained when the above-mentioned specified thickness is detected (specifically, the intensity of the above-mentioned reflected light or the amplitude of the amplitude spectrum, or the fitting rate between the spectroscopic spectrum and the simulation spectrum).

[0137] On the other hand, if the portion outside the modified region 11d is removed, it becomes impossible to detect the thickness using the thickness measuring device 64, or a thickness that does not correspond to the above-mentioned specified thickness is detected, and data that does not correspond to the data obtained when the above-mentioned specified thickness is detected is detected by the thickness measuring device 64.

[0138] Therefore, by comparing the above peel determination data stored in memory 90 with each of the data detected by thickness measuring device 64 by projecting measurement light toward the portion outside modified region 11d of substrate 11 included in bonded substrate 19, it is possible to determine whether this portion has been removed.

[0139] Furthermore, the processing apparatus of the present invention may include at least one of a position adjustment unit having components similar to those of the above-described position adjustment mechanism or a cleaning unit having components similar to those of the above-described cleaning unit, in addition to the components of the processing apparatus 92. Furthermore, in this case, the determination of whether or not the peeled portion 19a exists in the bonded substrate stack 19 and the determination of whether or not the portion outside the modified region 11d has been removed may be performed with the bonded substrate stack 19 supported on a positioning table provided in the position adjustment unit or a spinner table provided in the cleaning unit.

[0140] In other words, the determination step performed in the processing apparatus of the present invention is not limited to the above-mentioned determination step S7, i.e., the step performed while the substrate is held on the second holding table provided in the grinding unit 96. However, from the viewpoint of more quickly determining whether or not the peeled portion 19a exists in the bonded substrate stack 19 and whether or not the portion outside the modified region 11d has been removed, it is preferable that these determinations be performed while the substrate is held on the second holding table.

[0141] Furthermore, the method for grinding a bonded substrate of the present invention may be a method for grinding a bonded substrate in which edge trimming is performed on substrate 11 by a method different from the edge trimming of substrate 11 in the method for grinding a bonded substrate shown in Fig. 13. For example, in the method for grinding a bonded substrate of the present invention, edge trimming may be performed on substrate 11 using an annular cutting blade, and then the back surface 11b side of substrate 11 may be ground.

[0142] In addition, the structures and methods according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0143] 2: Grinding equipment 4: Base (4a: recess) 6:X direction movement mechanism 8: Guide rail 10: X-direction moving plate 11: Substrate (first substrate) (11a: front surface, 11b: back surface, 11c: side surface) (11d: modified area, 11e: crack) 12: Screw shaft 13: Device 14: Motor 15: Support substrate (second substrate) (15a: front surface, 15b: back surface) 16: Nut 17: Adhesive layer 18: Rotation mechanism 19: Bonded substrate (19a: Peeling portion) 20: Driven pulley 22: Tilt adjustment mechanism 24: Movable axis 26: Table base 28: Holding table (28a: frame, 28b: porous plate) 30: Table cover 32: Dustproof and waterproof cover 34:Support structure 36: Grinding unit 38:Z direction movement mechanism 40: Guide rail 42: Slider 44: Z-direction moving plate 46: Screw shaft 48: Motor 50: Nut 52: Support member 54: Spindle housing 56: Spindle 58: Motor 60: Mount 62: Grinding wheel (62a: grinding wheel, 62b: wheel base) 64: Thickness measuring instrument (inspection unit) 66: Measuring head 68: Light projection unit 70: Spectroscopic section 72: Light receiving part 74: Calculation section 76: Arm 78: Support shaft 80: Motor 82: Z-direction movement mechanism (82a: Z-direction movement plate, 82b: nut) (82c: screw shaft, 82d: motor) 84: Touch panel 86: Controller 88: Processor 90: Memory (90a: main storage device, 90b: auxiliary storage device) 92: Processing equipment 94: Modified area forming section 96: Grinding section 98: Inspection Department 100: Controller 102: Holding table (first holding table) 104: Laser beam irradiation unit (104a: laser oscillator, 104b: attenuator, 104c: branching unit) (104d: mirror, 104e: injection head)

Claims

1. a grinding step of grinding the first substrate of a bonded substrate including a first substrate and a second substrate bonded to the first substrate; a determining step of determining whether or not a peeled portion where a part of the first substrate is peeled from the second substrate exists in the bonded substrate stack after the grinding step is performed, The grinding step and the determination step are carried out in the same apparatus.

2. 2. The grinding method for a bonded substrate according to claim 1, wherein in the determining step, it is determined whether or not the peeled portion exists in the bonded substrate using a thickness measuring device for measuring the thickness of an arbitrary position in the bonded substrate or the first substrate.

3. 2. The method for grinding a bonded substrate according to claim 1, wherein in the determination step, it is determined whether each of the plurality of positions is the peeled portion based on a change in intensity of reflected light caused by projecting measurement light sequentially from the first substrate side toward the plurality of positions included in the bonded substrate.

4. 4. The grinding method for a bonded substrate according to claim 3, further comprising a display step of displaying an image including the bonded substrate in which the peeled portion and a portion other than the peeled portion are separated after the determination step is performed.

5. 3. The grinding method for a bonded substrate according to claim 2, wherein in the determining step, it is determined whether each of the plurality of positions is the peeled portion based on the thickness of the first substrate calculated from each of a plurality of spectral spectra obtained by projecting measurement light from the thickness measuring device sequentially from the first substrate side toward a plurality of positions included in the bonded substrate.

6. 6. The grinding method for a bonded substrate according to claim 5, further comprising a display step of displaying an image including the bonded substrate in which the peeled portion and a portion other than the peeled portion are separated after the determination step is performed.

7. 3. The method for grinding a bonded substrate according to claim 2, wherein in the determining step, whether or not each of the plurality of positions is the peeled portion is determined based on the amplitude of an amplitude spectrum obtained by performing a fast Fourier transform on each of a plurality of spectral spectra obtained by projecting measurement light from the thickness measuring device sequentially from the first substrate side toward a plurality of positions included in the bonded substrate and then dispersing reflected light generated by the measurement light.

8. 8. The grinding method for a bonded substrate according to claim 7, further comprising a display step of displaying an image including the bonded substrate in which the peeled portion and a portion other than the peeled portion are separated after the determination step is performed.

9. 3. The method for grinding a bonded substrate according to claim 2, wherein in the determining step, it is determined whether each of the plurality of positions is the peeled portion based on a fitting rate obtained when fitting each of a plurality of optical spectra obtained by projecting measurement light from the thickness measuring device sequentially from the first substrate side toward a plurality of positions included in the bonded substrate to a simulation spectrum to calculate the thickness of the first substrate.

10. 10. The grinding method for a bonded substrate according to claim 9, further comprising a display step of displaying an image including the bonded substrate in which the peeled portion and a portion other than the peeled portion are separated after the determination step is performed.

11. 11. The grinding method for a bonded substrate according to claim 1, wherein in the determining step, the bonded substrate is determined to be defective when the ratio or number of peeled portions in the bonded substrate exceeds a threshold value.

12. a holding step of holding the bonded substrate stack on a holding table so that the first substrate is exposed before the grinding step is performed; 11. The method for grinding a bonded substrate according to claim 1, wherein the grinding step and the determining step are each performed while the bonded substrate is held by the holding table.

13. a modified region forming step of forming an annular modified region inside the first substrate by irradiating the first substrate with a laser beam along an outer edge of the first substrate before carrying out the holding step; The grinding method for a bonded substrate as described in claim 12, wherein in the determination step, in addition to determining whether the peeled portion exists in the bonded substrate, it is also determined whether a portion of the first substrate outside the modified region has been removed.

14. a holding table for holding a bonded substrate including a first substrate and a second substrate bonded to the first substrate; a rotation mechanism for rotating the holding table; a grinding unit for grinding the bonded substrate; an inspection unit for inspecting the bonded substrate; a controller for controlling the rotation mechanism, the grinding unit, and the inspection unit; the controller controls the grinding unit to grind the first substrate while controlling the rotation mechanism to rotate the holding table that holds the bonded substrate with the first substrate exposed, and then controls the inspection unit to detect data used in determining whether or not a peeled portion, where a part of the first substrate has peeled off from the second substrate, is present in the bonded substrate.

15. the inspection unit includes a thickness measuring device for measuring the thickness of the bonded substrate or the first substrate at an arbitrary position; The grinding apparatus according to claim 14 , wherein the processor controls the inspection unit to detect, as the data, a thickness of the bonded substrate stack or the first substrate at each of a plurality of positions included in the bonded substrate stack.

16. the inspection unit includes a light-projecting unit for projecting measurement light and a light-receiving unit for receiving reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate stack, 15. The grinding apparatus according to claim 14, wherein the processor controls the inspection unit to detect, as the data, a change in intensity of the reflected light received by the light receiving unit when the light projecting unit sequentially projects the measurement light toward a plurality of positions included in the bonded substrate.

17. further comprising a display unit for displaying information about the bonded substrate; The grinding apparatus according to claim 16, wherein the processor controls the display unit to display an image including the bonded substrate in which the peeled portion and portions other than the peeled portion are separated after determining whether or not the peeled portion exists in the bonded substrate.

18. the thickness measuring instrument is a non-contact type thickness measuring instrument including a light projecting unit for projecting measurement light, a spectroscopic unit for spectroscopically separating reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate stack, and a light receiving unit for receiving the reflected light dispersed by the spectroscopic unit; 16. The grinding apparatus according to claim 15, wherein the processor controls the inspection unit to detect, as the data, a thickness of the first substrate calculated from each of a plurality of optical spectra obtained by projecting the measurement light from the light projecting unit sequentially toward a plurality of positions included in the bonded substrate, the reflected light being dispersed by the spectroscopic unit, and then received by the light receiving unit.

19. further comprising a display unit for displaying information about the bonded substrate; 19. The grinding apparatus according to claim 18, wherein the processor controls the display unit to display an image including the bonded substrate in which the peeled portion and portions other than the peeled portion are separated after determining whether the peeled portion exists in the bonded substrate.

20. the thickness measuring instrument is a non-contact type thickness measuring instrument including a light projecting unit for projecting measurement light, a spectroscopic unit for spectroscopically separating reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate stack, and a light receiving unit for receiving the reflected light dispersed by the spectroscopic unit; 16. The grinding device according to claim 15, wherein the processor controls the inspection unit to detect, as the data, amplitudes of amplitude spectra obtained by fast Fourier transform of each of a plurality of spectroscopic spectra obtained by projecting the measurement light from the light projecting unit sequentially toward a plurality of positions included in the bonded substrate, the reflected light being dispersed by the spectroscopic unit, and then receiving the reflected light by the light receiving unit.

21. further comprising a display unit for displaying information about the bonded substrate; The grinding apparatus according to claim 20, wherein the processor controls the display unit to display an image including the bonded substrate in which the peeled portion and portions other than the peeled portion are separated after determining whether the peeled portion exists in the bonded substrate.

22. the thickness measuring instrument is a non-contact type thickness measuring instrument including a light projecting unit for projecting measurement light, a spectroscopic unit for spectroscopically separating reflected light generated by projecting the measurement light from the first substrate side toward the bonded substrate stack, and a light receiving unit for receiving the reflected light dispersed by the spectroscopic unit; 16. The grinding apparatus according to claim 15, wherein the processor controls the inspection unit to detect, as the data, a fitting rate obtained when calculating the thickness of the first substrate by fitting each of a plurality of spectral spectra obtained by projecting the measurement light from the light projecting unit sequentially toward a plurality of positions included in the bonded substrate, the reflected light being dispersed by the spectroscopic unit, and then the reflected light being received by the light receiving unit, to a simulation spectrum.

23. further comprising a display unit for displaying information about the bonded substrate; 23. The grinding apparatus according to claim 22, wherein the processor controls the display unit to display an image including the bonded substrate in which the peeled portion and portions other than the peeled portion are separated after determining whether the peeled portion exists in the bonded substrate.

24. the controller further includes a memory for storing a threshold value for the percentage or number of peeled portions; 24. The grinding apparatus according to claim 14, wherein the processor determines that the bonded substrate is defective when the percentage or number of peeled portions in the bonded substrate exceeds the threshold value.

25. 24. The grinding apparatus according to claim 14, wherein the processor controls the inspection unit to inspect the bonded substrate stack held by the holding table.

26. a modified region forming section including a first holding table for holding a bonded substrate including a first substrate and a second substrate bonded to the first substrate, and a laser beam irradiation unit for irradiating a laser beam capable of forming a modified region inside the bonded substrate held by the first holding table; a grinding section including a second holding table for holding the bonded substrate stack, a rotation mechanism for rotating the second holding table, and a grinding unit for grinding the bonded substrate stack; an inspection section having an inspection unit for inspecting the bonded substrate; a controller for controlling the laser beam irradiation unit, the rotation mechanism, the grinding unit, and the inspection unit; the controller controls the laser beam application unit to irradiate the laser beam onto the first substrate along the outer edge of the first substrate included in the bonded substrate held on the first holding table with the first substrate exposed, thereby forming an annular modified region inside the first substrate, then controls the grinding unit to grind the first substrate while controlling the rotation mechanism to rotate the second holding table that holds the bonded substrate with the first substrate exposed, and then controls the inspection unit to detect data used in determining whether or not a peeled portion where a part of the first substrate has peeled off from the second substrate is present in the bonded substrate.

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