GRINDING HEAD

Abstract

According to some embodiments, a grinding head configured to grind a grinding target, the head includes a wheel including a rotating front surface and a plurality of grindstones arranged in an annular shape on the rotating front surface with a rotation axis of the rotating front surface as a center. Each of the plurality of grindstones includes a first surface configured to be in contact with the grinding target and a second surface inclined at an acute angle with respect to a traveling direction of the grindstone from the rotating front surface to the first surface.

Claims

1. A grinding head configured to grind a grinding target, the grinding head comprising: a wheel comprising a rotating front surface; and a plurality of grindstones arranged in an annular shape on the rotating front surface with a rotation axis of the rotating front surface as a center, wherein each of the plurality of grindstones comprise: a first surface configured to be in contact with the grinding target; and a second surface inclined at an acute angle with respect to a traveling direction of the grindstone from the rotating front surface to the first surface.

2. The grinding head of claim 1, wherein the grinding target comprises: a first semiconductor substrate; a second semiconductor substrate; a first layer between the first semiconductor substrate and the second semiconductor substrate; and a second layer provided between the first layer and the second semiconductor substrate and bonded to the first layer.

3. The grinding head of claim 2, the first surface is configured to be in contact with a front surface of the second semiconductor substrate.

4. The grinding head of claim 1, wherein the grinding target is supported by a stage and positioning of the grinding target is controlled during grinding.

5. The grinding head of claim 1, wherein grinding the grinding target comprises moving the grinding head to position the first surface of the grindstone in contact with the grinding target and rotating the rotating front surface.

6. A grinding head configured to grind a grinding target, the grinding head comprising: a wheel comprising a rotating front surface; and a plurality of grindstones arranged in an annular shape on the rotating front surface with a rotation axis of the rotating front surface as a center, wherein each of the plurality of grindstones comprise: a first surface configured to be in contact with the grinding target; and a second surface inclined at an inclination angle of 60 or more and 75 or less with respect to a traveling direction of the grindstone from the rotating front surface to the first surface; wherein a width d of the grindstone, an inclination width s of the second surface, an inclination angle of a slit between adjacent grindstones with respect to a first straight line along a radial direction of the rotating front surface, an angle x formed by a first tangent to a trajectory, drawn by an outer side surface of the grindstone when the rotating front surface rotates, passing through an intersection point between the trajectory and a peripheral edge of the grinding target, and a second tangent to the peripheral edge of the grinding target passing through the intersection point, and a width p of the slit satisfy: $d\tan -\frac{d\tan -s}{\tan }\tan x>p+s.$

7. The grinding head of claim 6, wherein the grinding target comprises: a first semiconductor substrate; a second semiconductor substrate; a first layer between the first semiconductor substrate and the second semiconductor substrate; and a second layer provided between the first layer and the second semiconductor substrate and bonded to the first layer.

8. The grinding head of claim 7, the first surface is configured to be in contact with a front surface of the second semiconductor substrate.

9. The grinding head of claim 6 wherein the grinding target is supported by a stage and positioning of the grinding target is controlled during grinding.

10. The grinding head of claim 6, wherein grinding the grinding target comprises moving the grinding head to position the first surface of the grindstone in contact with the grinding target and rotating the rotating front surface.

11. A grinding head configured to grind a grinding target, the grinding head comprising: a wheel comprising a rotating front surface; a plurality of grindstones arranged in an annular shape on the rotating front surface with a rotation axis of the rotating front surface as a center, wherein each of the plurality of grindstones comprise: a first surface configured to be contact with the grinding target, and a second surface that extends from the rotating front surface to the first surface, a planar shape on the first surface is a pentagon, and a slit between adjacent grindstones extends in a direction intersecting a radial direction of the rotating front surface.

12. The grinding head of claim 11, wherein the grinding target comprises: a first semiconductor substrate; a second semiconductor substrate; a first layer between the first semiconductor substrate and the second semiconductor substrate; and a second layer provided between the first layer and the second semiconductor substrate and bonded to the first layer.

13. The grinding head of claim 12, the first surface is configured to be in contact with a front surface of the second semiconductor substrate.

14. The grinding head of claim 11, wherein the grinding target is supported by a stage and positioning of the grinding target is controlled during grinding.

15. The grinding head of claim 11, wherein grinding the grinding target comprises moving the grinding head to position the first surface of the grindstone in contact with the grinding target and rotating the rotating front surface.

Description

DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a schematic diagram showing a configuration example of a grinding device.

[0005] FIG. 2 is a schematic diagram showing an example of a grinding method in the related art.

[0006] FIG. 3 is a schematic diagram showing an example of a grinding method in the related art.

[0007] FIG. 4 is a schematic diagram showing an example of a grinding method according to an embodiment.

[0008] FIG. 5 is a schematic diagram showing an example of a grinding method according to an embodiment.

[0009] FIG. 6 is a schematic diagram showing an example of a three-dimensional shape of a grindstone.

[0010] FIG. 7 is a schematic diagram showing an example of a three-dimensional shape of a grindstone.

[0011] FIG. 8 is a schematic diagram showing a design example of a shape of a grindstone.

DETAILED DESCRIPTION

[0012] Embodiments provide a grinding head, a grinding device, and a grinding method that reduce damage to a grinding target by grinding.

[0013] In general, according to one embodiment, a grinding head configured to grind a grinding target includes a wheel that include a rotating front surface and a plurality of grindstones arranged in an annular shape on the rotating front surface with a rotation axis of the rotating front surface as a center. Each of the plurality of grindstones includes a first surface configured to be in contact (e.g., directly) with the grinding target and a second surface that is inclined at an acute angle with respect to a traveling direction of the grindstone from the rotating front surface to the first surface.

[0014] Hereinafter, embodiments will be described with reference to the drawings. The relationship between the thickness and the plane dimension of each element shown in the drawings, the ratio of the thicknesses of each element, and the like may differ from the actual product. In addition, in the embodiments, substantially the same elements will be given the same reference numerals, and the description thereof will be omitted as appropriate.

Configuration Example of Grinding Device

[0015] FIG. 1 is a schematic diagram showing a configuration example of a grinding device. FIG. 1 shows a grinding device 100. FIG. 1 further shows an X-axis, a Y-axis, and a Z-axis. The X-axis, the Y-axis, and the Z-axis intersect each other perpendicularly. For example, the Z-axis extends in a thickness direction of a grinding target 10.

[0016] The grinding device 100 can grind the grinding target 10. The grinding device 100 includes a stage 1 and a grinding head 2.

[0017] For example, the stage 1 includes a function of rotating the grinding target 10 with a rotation axis AS1 in the Z-axis direction of the stage 1 as a center. The stage 1 includes a front surface (placement surface) 1a on which the grinding target 10 is placed. The stage 1 is configured to support the grinding target and control its positioning during grinding. For example, the planar shape on a front surface 1a is a circular shape. For example, the X-axis and the Y-axis extend in a direction parallel to the front surface 1a. For example, the Z-axis intersects the front surface 1a perpendicularly. The front surface 1a is rotatable with the rotation axis AS1 as a center. The stage 1 may be movable in the X-axis direction, the Y-axis direction, and the Z-axis direction. For example, the stage 1 may be driven by a drive device including a motor. The stage 1 may have a suction device capable of picking up the grinding target 10. An example of the suction device includes a vacuum chuck.

[0018] An example of the grinding target 10 is a substrate including a semiconductor device under manufacturing. For example, the grinding target 10 includes a semiconductor substrate 11 (e.g., first semiconductor substrate), a semiconductor substrate 12 (e.g., second semiconductor substrate), a layer 13 (e.g., first layer) between the semiconductor substrate 11 and the semiconductor substrate 12, and a layer 14 (e.g., second layer) between the semiconductor substrate 12 and the layer 13. The structure of the grinding target 10 is not limited thereto.

[0019] Each of the semiconductor substrate 11 and the semiconductor substrate 12 is, for example, a silicon wafer.

[0020] The layer 13 is provided on the semiconductor substrate 11. For example, the layer 13 includes a memory cell array in a semiconductor device such as a NAND flash memory.

[0021] The layer 14 is provided on the semiconductor substrate 11. The layer 14 includes a peripheral circuit including a CMOS circuit in a semiconductor device such as a NAND flash memory. The front surface of the layer 14 is bonded to the front surface of the layer 13. As a result, the peripheral circuit and the memory cell array are electrically connected.

[0022] The grinding head 2 includes a wheel 21 and a grindstone 22.

[0023] The wheel 21 includes a rotating front surface 21a. For example, the planar shape on the rotating front surface 21a is a circular shape. The rotating front surface 21a is rotatable with a rotation axis AS2 in the Z-axis direction as a center. The rotating front surface 21a overlaps, for example, a front surface 10a of the grinding target 10 in the Z-axis direction when the grinding target 10 is ground. The example of the front surface 10a includes a front surface (exposed surface) of the semiconductor substrate 12. For example, the wheel 21 may be driven by a drive device including a motor.

[0024] The grindstone 22 can grind the grinding target 10. The grinding head 2 includes a plurality of grindstones 22. The plurality of grindstones 22 are provided on the rotating front surface 21a and are arranged side by side along a peripheral edge on the rotating front surface 21a. For example, the plurality of grindstones 22 may be arranged side by side in an annular shape on the rotating front surface 21a with the rotation axis AS2 as a center. The number of the plurality of grindstones 22 is not particularly limited.

[0025] The grinding head 2 includes the function of pressing the grindstone 22 (a portion that is in contact with the grinding target 10) against the front surface 10a and grinding the grindstone 22. Grinding the grinding target can include moving the grinding head to position the first surface of the grindstone in contact with the grinding target and rotating the rotating front surface. Grinding the grinding target can include applying force to maintain contact between the grindstone 22 and the grinding target 10, adjusting the relative positioning between the grinding target 10 and the grindstone 22, and/or controlling rotational motion to perform material removal. Grinding the grinding target can include controlling the depth of material removal, adjusting the pressure exerted by the grindstone 22, modifying the grinding path to achieve uniform processing, and/or dynamically altering grinding parameters based on feedback data. For example, the grinding head 2 may be movable along each of the X-axis direction, the Y-axis direction, and the Z-axis direction. For example, the grinding head 2 includes the function of rotating the grindstone 22 with the rotation axis AS2 as a center. For example, the grinding head 2 may be driven by a drive device including a motor.

[0026] The stage 1 and the grinding head 2 may be controlled by, for example, a control device. The stage 1 is configured to support the grinding target and control its positioning during grinding. The control device may be configured using hardware such as a processor. The control device can be implemented a processing circuit including at least one processor or memory. The grinding head 2 operates in coordination with the processing circuit to regulate grinding parameters such as rotational speed, grinding force, and movement along g multiple axes based on predefined instructions or real-time feedback. The processing circuit can execute control algorithms that adjust the interaction between the grindstones and the grinding target to improve material removal and/or maintain consistent grinding performance. Each operation may be stored as an operation program in a computer-readable recording medium such as a memory, and each operation may be executed by appropriately reading the operation program stored in the recording medium by the hardware.

Grinding Method

[0027] Next, an example of a grinding method using the grinding device 100 will be described. First, the grinding target 10 is placed on the front surface 1a of the stage 1. The stage 1 can be configured to secure, move, and/or rotate the grinding target 10 in one or more directions to facilitate grinding operations. The stage 1 may include mechanisms for adjusting the position, orientation, and/or stability of the grinding target 10, such as rotational drives, linear actuators, and/or vacuum-based holding systems. The front surface 1a is in contact with a surface opposite to the front surface 10a of the grinding target 10 (rear surface (exposed surface) of the semiconductor substrate 11). The grinding target 10 may be placed on the front surface 1a using a conveyance device such as a robot arm. The conveyance device may be controlled by the control device.

[0028] Next, the front surface 10a is rotated in a first rotation direction R1 (for example, clockwise) while a grinding fluid such as pure water is supplied to the grinding surface (front surface 10a), the grinding head 2 is moved in the Z-axis direction to bring the front surface (grinding surface) of the grindstone 22 into contact with the front surface 10a of the grinding target 10 by the grinding head 2, and the rotating front surface 21a is rotated in a second rotation direction R2 (for example, counterclockwise) opposite to the first rotation direction. As a result, the grinding target 10 is ground from the front surface 10a, for example. The semiconductor substrate 12 may be removed by grinding the grinding target 10. As a result, the grinding target 10 can be made thin.

[0029] FIGS. 2 and 3 are schematic diagrams showing an example of a grinding method in the related art. FIG. 2 is a schematic plan view showing the grinding target 10 and the grinding head 2 during grinding. FIG. 3 is a schematic cross-sectional view showing the grinding target 10 and the grinding head 2 during grinding. The grinding head 2 includes a plurality of grindstones 22. The plurality of grindstones 22 are arranged in an annular shape on the rotating front surface 21a with the rotation axis AS2 on the rotating front surface 21a as a center. A slit ST is formed between the adjacent grindstones 22. For example, the slit ST is a path in which a grinding fluid flows.

[0030] When the grindstone 22 is in a rectangular parallelepiped shape, a lower surface 22a of the grindstone 22 is provided parallel to the rotating front surface 21a and is directly in contact with (e.g., in physical contact without an intermediary material or layer affecting the grinding interaction) the grinding target 10. A front side surface 22b of the grindstone 22 faces the front of the grindstone 22 and extends from the rotating front surface 21a to the front side surface 22b at a right angle with respect to the rotating front surface 21a in the second rotation direction R2 of the rotating front surface 21a (a traveling direction of the grindstone 22). That is, an angle T formed by the lower surface 22a and the front side surface 22b is 90 degrees.

[0031] When the grindstone 22 is in a rectangular parallelepiped shape, a contact area between the lower surface 22a of the grindstone 22 and the grinding target 10 is small, and a peripheral edge of the grinding target is not intermittently and directly in contact with (e.g., in physical contact without being separated by any gap or non-physical barrier) any of the grindstones 22 during grinding. Therefore, for example, when an unbonded portion is present between the layer 13 and the layer 14, the semiconductor substrate 12 and the layer 13 are peeled off from the layer 14 and lifted, as shown in FIG. 3, by the contact between the lower surface 22a or the front side surface 22b of the grindstone 22 and the unbonded portion in the slit ST between the adjacent grindstones 22. For example, this causes harm such as malfunction of operation of a semiconductor device in which the grinding target 10 is damaged during manufacturing.

[0032] On the other hand, in the grinding method according to the embodiment, the grinding target 10 is ground by using the grinding head 2 including the grindstone 22 including a three-dimensional shape different from a rectangular parallelepiped shape. FIGS. 4 and 5 are schematic diagrams showing an example of the grinding method according to the embodiment. FIG. 4 is a schematic plan view showing the grinding target 10 and the grinding head 2 during grinding. FIG. 5 is a schematic cross-sectional view showing the grinding target 10 and the grinding head 2 during grinding.

[0033] In the grinding method according to the embodiment, the lower surface 22a of the grindstone 22 is provided parallel to the rotating front surface 21a and is directly in contact with the grinding target 10. A front side surface 22b of the grindstone 22 faces the front of the grindstone 22 and extends from the rotating front surface 21a to the front side surface 22b that is inclined at an acute angle with respect to the rotating front surface 21a in the second rotation direction R2 of the rotating front surface 21a (the traveling direction of the grindstone 22). It is preferable that the angle T formed by the lower surface 22a and the front side surface 22b is, for example, 60 or more and 75 or less. Grinding the grinding target can include moving the grinding head to position the first surface of the grindstone in contact with the grinding target and rotating the rotating front surface. Grinding the grinding target can involve controlling the relative positioning of the grindstone 22 and the grinding target 10 along multiple axes, maintaining a predetermined contact force, adjusting the rotational speed of the rotating front surface 21a, and/or applying a grinding fluid to facilitate material removal and cooling. Additionally, the process may involve coordinating the movement of the stage 1 and the grinding head 2 to regulate the grinding depth, distribute material removal evenly across the surface, and/or reduce the likelihood of defects such as chipping or delamination

[0034] In the second rotation direction R2 of the rotating front surface 21a (the traveling direction of the grindstone 22), the contact area between the grindstone 22 and the grinding target 10 can be increased when the grindstone 22 includes a rectangular parallelepiped shape by inclining the front side surface 22B at an acute angle with respect to the rotating front surface 21a. As a result, since a force applied to the grinding target 10 when the grindstone 22 and the grinding target 10 come into contact with each other can be dispersed, for example, peeling of the semiconductor substrate 12 and the layer 14 can be prevented. Therefore, the damage of the grinding target 10 by grinding can be reduced.

[0035] Furthermore, it is preferable that the slit ST extends to be inclined with respect to the radial direction of the rotating front surface 21a. In other words, it is preferable that the slit ST extends in a direction intersecting a radial direction of the rotating front surface 21a. As a result, since the front surface 10a of the grinding target 10 can be always kept in a state of being directly in contact with at least one of the plurality of grindstones 22, the grinding target 10 can be intermittently pressed by at least one of the grindstones 22. Therefore, the peeling of the semiconductor substrate 12 and the layer 14 can be prevented by grinding, and the streaks and chipping formed on the front surface 10a of the grinding target 10 can be reduced. Therefore, the damage of the grinding target 10 can be reduced. In addition, by inclining the slit ST with respect to the radial direction of the rotating front surface 21a, the chips and the grinding fluid generated during grinding can be easily discharged from the front surface 10a of the grinding target 10.

[0036] In the embodiment, the three-dimensional shape of the grindstone 22 is preferably appropriately designed to have a suitable shape for effectively preventing the damage of the grinding target 10 as described above. FIGS. 6 and 7 are schematic diagrams showing an example of a three-dimensional shape of a grindstone. FIGS. 6 and 7 schematically show a lower surface 22A, a front side surface 22B, an upper surface 22C, a rear side surface 22D, an inner side surface 22E, and an outer side surface 22F of the grindstone 22.

[0037] The lower surface 22A is a lower surface of the grindstone 22 when the grindstone 22 is viewed from above toward below in a direction perpendicular to the traveling direction of the grindstone 22 (a thickness direction of the grindstone 22). The traveling direction can be the direction in which the grindstone 22 moves relative to the grinding target 10 due to the rotation of the rotating front surface 21a, following a tangential path along its trajectory. Additionally, the traveling direction can correspond to the second rotation direction R2 of the rotating front surface 21a and can extend from the rear side surface 22D to the front side surface 22B of the grindstone 22 as the grinding head 2 operates. As shown in FIG. 5, the traveling direction generally extends from the rear side surface 22D of a grindstone 22 to its front side surface 22B as the grindstone 22 rotates about the rotation axis AS2. The lower surface 22A faces the lower side of the grindstone 22 in a thickness direction of the grindstone 22. The lower surface 22A can be directly in contact with the front surface 10a of the grinding target 10 and corresponds to the lower surface 22a in FIG. 5. A planar shape of the lower surface 22A includes a pentagon shape connecting a vertex A1, a vertex A2, a vertex A3, a vertex A4, and a vertex A5. This indicates that the front side surface 22B is inclined at an acute angle with respect to the rotating front surface 21a.

[0038] The lower surface 22A includes a side A1-A2 connecting the vertex A1 and the vertex A2, a side A2-A3 connecting the vertex A2 and the vertex A3, a side A3-A4 connecting the vertex A3 and the vertex A4, a side A4-A5 connecting the vertex A4 and the vertex A5, and a side A5-A1 connecting the vertex A5 and the vertex A1. The side A1-A2 faces the front of the grindstone 22 in the traveling direction of the grindstone 22 and is inclined at an obtuse angle with respect to the side A2-A3. The side A2-A3 faces the front of the grindstone 22 in the traveling direction of the grindstone 22, is inclined with respect to the radial direction of the rotating front surface 21a, and is inclined at an obtuse angle with respect to the side A3-A4. The side A3-A4 faces the inside (rotation axis AS2 side) of the grindstone 22 in the traveling direction of the grindstone 22. The side A4-A5 faces the side A2-A3 and is inclined at an acute angle with respect to the side A3-A4. The side A4-A5 faces the rear of the grindstone 22 in the traveling direction of the grindstone 22 and extends parallel to the side A2-A3. The side A5-A1 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22, faces the side A3-A4, and extends parallel to the side A3-A4. An angle formed by the side A1-A2 and the side A5-A1 is, for example, 90. An angle formed by the side A2-A3 and the side A3-A4 is the same as an angle formed by the side A4-A5 and the side A5-A1.

[0039] The front side surface 22B is a front side surface of the grindstone 22 when viewed from the front toward the rear of the grindstone 22 in the traveling direction of the grindstone 22. The front side surface 22B faces the front of the grindstone 22 in the traveling direction of the grindstone 22. At least a part of the front side surface 22B can be directly in contact with the front surface 10a of the grinding target 10 and corresponds to the front side surface 22b in FIG. 5. A planar shape on the front side surface 22B includes a quadrangular shape connecting a vertex B1, a vertex B2, a vertex B3, and a vertex B4.

[0040] The front side surface 22B includes a side B1-B2 connecting the vertex B1 and the vertex B2, a side B2-B3 connecting the vertex B2 and the vertex B3, a side B3-B4 connecting the vertex B3 and the vertex B4, and a side B4-B1 connecting the vertex B4 and the vertex B1. The side B1-B2 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22 and extends perpendicularly to the side B2-B3 and the side B4-B1. The side B2-B3 is shorter than the side B1-B4 and faces the lower side of the grindstone 22 in the thickness direction of the grindstone 22. The side B3-B4 faces the inside of the grindstone 22 in the traveling direction of the grindstone 22, is inclined at an obtuse angle with respect to the side B2-B3, and is inclined at an acute angle with respect to the side B4-B1. The side B4-B1 faces the side B2-B3, extends parallel to the side B2-B3, and faces the upper side of the grindstone 22 in the thickness direction of the grindstone 22.

[0041] The upper surface 22C is an upper surface of the grindstone 22 when the grindstone 22 is viewed from above toward below in the thickness direction of the grindstone 22. The upper surface 22C faces the upper side of the grindstone 22 in the thickness direction of the grindstone 22. The upper surface 22C is provided on the side opposite to the lower surface 22A and is fixed to the rotating front surface 21a. The planar shape of the upper surface 22C includes a pentagon shape connecting the vertex C1, the vertex C2, the vertex C3, the vertex C4, and the vertex C5. This indicates that the rear side surface 22D is inclined at an obtuse angle with respect to the rotating front surface 21a. The vertex C2 is at the same position as the vertex B4.

[0042] The upper surface 22C includes a side C1-C2 connecting the vertex C1 and the vertex C2, a side C2-C3 connecting the vertex C2 and the vertex C3, a side C3-C4 connecting the vertex C3 and the vertex C4, a side C4-C5 connecting the vertex C4 and the vertex C5, and a side C5-C1 connecting the vertex C5 and the vertex C1. The side C1-C2 faces the front of the grindstone 22 in the traveling direction of the grindstone 22 and is inclined at an acute angle with respect to the side C2-C3. The side C2-C3 faces the inside of the grindstone 22 in the traveling direction of the grindstone 22. The side C3-C4 faces the rear of the grindstone 22 in the traveling direction of the grindstone 22, faces the side C1-C2, extends parallel to the side C1-C2, and is inclined at an obtuse angle with respect to the side C2-C3. The side C4-C5 faces the rear of the grindstone 22 in the traveling direction of the grindstone 22 and is inclined at an obtuse angle with respect to the side C3-C4. The side C5-C1 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22, faces the side C2-C3, and extends parallel to the side C2-C3. An angle formed by the side C4-C5 and the side C5-C1 is, for example, 90. An angle formed by the side C1-C2 and the side C5-C1 is the same as an angle formed by the side C2-C3 and the side C3-C4.

[0043] The rear side surface 22D is a rear surface of the grindstone 22 when viewed from the front toward the rear of the grindstone 22 in the traveling direction of the grindstone 22. The rear side surface 22D faces the rear of the grindstone 22 in the traveling direction of the grindstone 22. At least a part of the rear side surface 22D can be directly in contact with the front surface 10a of the grinding target 10. A planar shape of the rear side surface 22D includes a quadrangular shape connecting a vertex D1, a vertex D2, a vertex D3, and a vertex D4.

[0044] The rear side surface 22D includes a side D1-D2 connecting the vertex D1 and the vertex D2, a side D2-D3 connecting the vertex D2 and the vertex D3, a side D3-D4 connecting the vertex D3 and the vertex D4, and a side D4-D1 connecting the vertex D4 and the vertex D1. The side D1-D2 faces the inside of the grindstone 22 in the traveling direction of the grindstone 22 and is inclined at an acute angle with respect to the side D2-D3. The side D2-D3 faces the side D4-D1, extends parallel to the side D4-D1, and faces the lower side of the grindstone 22 in the thickness direction of the grindstone 22. The side D3-D4 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22 and extends perpendicularly to the side D2-D3 and the side D4-D1. The side D4-D1 faces the side D2-D3, extends parallel to the side D2-D3, and faces the upper side of the grindstone 22 in the thickness direction of the grindstone 22. The vertex D2 is at the same position as the vertex A4.

[0045] The inner side surface 22E is an inner surface when viewed from the inside toward the outside of the grindstone 22 in a direction perpendicular to each of the thickness direction and the traveling direction of the grindstone 22. The inner side surface 22E faces the inside of the grindstone 22 in the traveling direction of the grindstone 22. A planar shape of the inner side surface 22E includes a quadrangular shape including a vertex E1, a vertex E2, a vertex E3, and a vertex E4. Furthermore, the shape of the grindstone 22 including the inner side surface 22E of the grindstone 22 when viewed from the inside can be regarded as a parallelogram. The inner side surface 22E includes a side E1-E2 connecting the vertex E1 and the vertex E2, a side E2-E3 connecting the vertex E2 and the vertex E3, a side E3-E4 connecting the vertex E3 and the vertex E4, and a side E4-E1 connecting the vertex E4 and the vertex E1. The vertex E1 is at the same position as the vertex B4 and the vertex C2. The vertex E2 is at the same position as the vertex A3. The vertex E3 is at the same position as the vertex A4 and the vertex D2. The vertex E4 is at the same position as the vertex C3.

[0046] The side E1-E2 faces the front side of the grindstone 22 in the traveling direction of the grindstone 22, extends parallel to the side E3-E4, and extends perpendicularly to the side E2-E3 and the side E4-E1. The side E2-E3 faces the lower side of the grindstone 22 in the thickness direction of the grindstone 22. The side E3-E4 faces the rear side of the grindstone 22 in the traveling direction of the grindstone 22 and extends perpendicularly to the side E2-E3 and the side E4-E1. The side E4-E1 faces the upper side of the grindstone 22 in the thickness direction of the grindstone 22.

[0047] The outer side surface 22F is an outer surface when viewed from the outside toward the inside of the grindstone 22 in a direction perpendicular to each of the thickness direction and the traveling direction of the grindstone 22. The outer side surface 22F faces the outside of the grindstone 22 in the traveling direction of the grindstone 22. The planar shape of the outer side surface 22F includes a quadrangular shape including a vertex F1, a vertex F2, a vertex F3, and a vertex F4. Furthermore, the shape of the grindstone 22 including the outer side surface 22F of the grindstone 22 when viewed from the outside can be regarded as a parallelogram. The outer side surface 22F includes a side F1-F2 connecting the vertex F1 and the vertex F2, a side F2-F3 connecting the vertex F2 and the vertex F3, a side F3-F4 connecting the vertex F3 and the vertex F4, and a side F4-F1 connecting the vertex F4 and the vertex F1. The vertex F1 is at the same position as the vertex C5 and the vertex D4. The vertex F2 is at the same position as the vertex A5. The vertex F3 is at the same position as the vertex A1 and the vertex B2. The vertex F4 is at the same position as the vertex C1.

[0048] The side F1-F2 faces the rear side of the grindstone 22 in the traveling direction of the grindstone 22, extends parallel to the side F3-F4, and extends perpendicularly to the side F2-F3 and the side F4-F1. The side F2-F3 faces the lower side of the grindstone 22 in the thickness direction of the grindstone 22. The side F3-F4 faces the front side of the grindstone 22 in the traveling direction of the grindstone 22 and extends perpendicularly to the side F2-F3 and the side F4-F1. The side F4-F1 faces the upper side of the grindstone 22 in the thickness direction of the grindstone 22.

[0049] The grindstone 22 shown in FIGS. 6 and 7 may further have a surface (C2-B3-A3) connecting the vertex C2, the vertex B3, and the vertex A3, a surface (C3-A4-D1) connecting the vertex C3, the vertex A4, and the vertex D1, a surface (C1-B1-E1) connecting the vertex C1, the vertex B1, and the vertex E1, a surface (A4-A5-D3) connecting the vertex A4, the vertex A5, and the vertex D3, a surface (C5-D3-A5) connecting the vertex C5, the vertex D3, and the vertex A5, and a surface (C1-A1-B1) connecting the vertex C1, the vertex A1, and the vertex B1.

[0050] The surface (C2-B3-A3) faces the front of the grindstone 22 in the traveling direction of the grindstone 22. The surface (C2-B3-A3) connects the lower surface 22A, the front side surface 22B, and the inner side surface 22E. A planar shape of the surface (C2-B3-A3) includes a triangular shape connecting the vertex C2, the vertex B3, and the vertex A3. The surface (C2-B3-A3) includes a side C2-B3 connecting the vertex C2 and the vertex B3, a side B3-A3 connecting the vertex B3 and the vertex A3, and a side A3-C2 connecting the vertex A3 and the vertex C2. The side C2-B3 faces the front side of the grindstone 22 in the traveling direction of the grindstone 22. The side B3-A3 faces the front side and the lower side of the grindstone 22 in the traveling direction of the grindstone 22. The side A3-C2 faces the front side of the grindstone 22 in the traveling direction of the grindstone 22. The surface (C2-B3-A3) is inclined at an acute angle with respect to the rotating front surface 21a. The surface (C2-B3-A3) is inclined at an obtuse angle with respect to the front side surface 22B and the inner side surface 22E. The surface (C2-B3-A3) may not be directly in contact with the front surface 10a of the grinding target 10.

[0051] The surface (C3-A4-D1) connects the upper surface 22C, the rear side surface 22D, and the inner side surface 22E. A planar shape of the surface (C3-A4-D1) includes a triangular shape including the vertex C3, the vertex A4, and the vertex D1. The surface (C3-A4-D1) includes a side C3-A4 connecting the vertex C3 and the vertex A4, a side A4-D1 connecting the vertex A4 and the vertex D1, and a side D1-C3 connecting the vertex D1 and the vertex C3. The side C3-A4 faces the inside of the grindstone 22 in the traveling direction of the grindstone 22. The side A4-D1 faces the rear side of the grindstone in the traveling direction of the grindstone 22. The side D1-C3 faces the upper side of the grindstone 22 in the thickness direction of the grindstone 22. The surface (C3-A4-D1) is inclined at an obtuse angle with respect to the rotating front surface 21a. The surface (C3-A4-D1) is inclined at an obtuse angle with respect to the rear side surface 22D and the inner side surface 22E. The surface (C3-A4-D1) may not be directly in contact with the rotating front surface 21a.

[0052] The surface (C1-B1-E1) connects the front side surface 22B, the upper surface 22C, and the outer side surface 22F. A planar shape of the surface (C1-B1-E1) includes a triangular shape including the vertex C1, the vertex B1, and the vertex E1. The surface (C1-B1-E1) includes a side C1-B1 connecting the vertex C1 and the vertex B1, a side B1-E1 connecting the vertex B1 and the vertex E1, and a side E1-C1 connecting the vertex E1 and the vertex C1. The side C1-B1 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22. The side B1-E1 faces the front side of the grindstone 22 in the traveling direction of the grindstone 22. The side E1-C1 faces the upper side of the grindstone 22 in the traveling direction of the grindstone 22. The surface (C1-B1-E1) is inclined at an obtuse angle with respect to the rotating front surface 21a. The surface (C1-B1-E1) is inclined at an obtuse angle with respect to the front side surface 22B, the upper surface 22C, and the inner side surface 22E. The surface (C1-B1-E1) may not be directly in contact with the rotating front surface 21a.

[0053] The surface (A4-A5-D3) connects the lower surface 22A and the rear side surface 22D. A planar shape of the surface (A4-A5-D3) includes a triangular shape connecting the vertex A4, the vertex A5, and the vertex D3. The surface (A4-A5-D3) includes a side A4-A5, a side A5-D3 connecting the vertex A5 and the vertex D3, and a side D3-A4 connecting the vertex D3 and the vertex A4. The side A5-D3 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22. The side D3-A4 faces the rear side of the grindstone 22 in the traveling direction of the grindstone 22. The surface (A4-A5-D3) is inclined at an acute angle with respect to the rotating front surface 21a. The surface (A4-A5-D3) is inclined at an obtuse angle with respect to the lower surface 22A and the rear side surfaces 22D and 22E. The surface (A4-A5-D3) may not be directly in contact with the front surface 10a of the grinding target 10.

[0054] The surface (C1-A1-B1) connects the front side surface 22B and the outer side surface 22F. A planar shape of the surface (C1-A1-B1) includes a triangular shape connecting the vertex C1, the vertex A1, and the vertex B1. The surface (C1-A1-B1) includes a side C1-A1 connecting the vertex C1 and the vertex A1, a side A1-B1 connecting the vertex A1 and the vertex B1, and a side B1-C1 connecting the vertex B1 and the vertex C1. The side C1-A1 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22. The side A1-B1 faces the front of the grindstone 22 in the traveling direction of the grindstone 22. The side B1-C1 faces the outside of the grindstone 22 in the traveling direction of the grindstone 22. The surface (C1-A1-B1) is inclined at an acute angle with respect to the rotating front surface 21a. The surface (C1-A1-B1) is inclined at an obtuse angle with respect to the lower surface 22A and the rear side surfaces 22D and 22E. The surface (C1-A1-B1) may not be directly in contact with the front surface 10a of the grinding target 10.

[0055] When a plurality of grindstones 22 including the shapes shown in FIGS. 6 and 7 are disposed, the shape of the grindstone 22 is preferably designed as follows. FIG. 8 is a schematic diagram showing a design example of the shape of the grindstone 22. FIG. 8 shows the lower surface 22A of each of the two grindstones 22 adjacent to each other.

[0056] It is preferable that a width d of the grindstone 22, an inclination width s of the front side surface 22B, an inclination angle of the slit ST (e.g., gap between grindstones 22 is oriented relative to the radial direction of the rotating front surface 21a) between the adjacent grindstones 22 with respect to a straight line L1 along the radial direction of the rotating front surface 21a, an angle x formed by a tangent L4 to the trajectory L2, drawn by the outer side surface 22F of the grindstone 22 when the rotating front surface 21a rotates, passing through an intersection point CP between the trajectory L2 and a peripheral edge L3 of the grinding target 10, and a tangent L5 to the peripheral edge L3 of the grinding target 10 passing through the intersection point CP, and a width p of the slit ST satisfy following Expression (1). The width d can be defined, for example, by a length between the side A3-A4 and the side A5-A1. The inclination width s of the grindstone 22 can be defined by, for example, the length of a straight line A1-A6 connecting an intersection point A6 between the side A2-A3 and the side A1-A5 when the side A2-A3 and the side A1-A5 are extended, and the vertex A1. The straight line L1 passes through the rotation axis AS2 on the rotating front surface 21a. The inclination angle can be defined, for example, by an angle formed by the L1 and the side A4-A5 of the grindstone 22. The angle x can be defined by an inclination angle of the tangent L5 with respect to the tangent L4. The width p can be defined by, for example, a maximum length (maximum width of the slit ST) between the side A4-A5 of the front grindstone 22 and the side A2-A3 of the rear grindstone 22 in two adjacent grindstones 22 (Expression (1)).

[00001]$\begin{array}{cc}d\tan -\frac{d\tan -s}{\tan }\tan x>p+s& \left(\mathrm{Expression}1\right)\end{array}$

[0057] Here, the basis for deriving Expression (1) will be described. Expression (1) is calculated, for example, as follows. First, a distance 11 from the straight line L1 to the vertex A4 is represented by Expression (2).

[00002]$\begin{array}{cc}l1=d\tan & \left(\mathrm{Expression}2\right)\end{array}$

[0058] In addition, a distance 12 from the side A3-A4 to the vertex A2 is represented by Expression (3).

[00003]$\begin{array}{cc}l2=d-\frac{s}{\tan }=\frac{d\tan -s}{\tan }& \left(\mathrm{Expression}3\right)\end{array}$

[0059] A distance 13 from the side A1-A2 is represented by Expression (4) for an intersection point P1 between the tangent L5 and the side A3-A4 when the tangent L5 exists on the vertex A2 from Expression (3). Here, the intersection point P1 is an intersection point between the side A3-A4 and the grinding target 10 when the grinding target 10 comes into contact with the rear grindstone 22.

[00004]$\begin{array}{cc}l3=l2\tan x=\frac{d\tan -s}{\tan }\tan x& \left(\mathrm{Expression}4\right)\end{array}$

[0060] Therefore, the distance from the straight line L1 to the intersection point P1 is a value obtained by adding the width p, the inclination width s, and the distance 13 of the slit ST as shown in FIG. 8, and when the intersection point P1 is in front of the vertex A4 of the front grindstone 22, the state where any one of the front grindstone 22 and the rear grindstone 22 is in contact with the grinding target 10 can be kept. Therefore, it is preferable that Expression (5) is satisfied, and Expression (1) can be derived from Expressions (2), (4), and (5).

[00005]$\begin{array}{cc}l1>p+s+l3& \left(\mathrm{Expression}5\right)\end{array}$

[0061] By satisfying Expression (1), at least one of the plurality of grindstones 22 can be always kept in a state of being directly in contact with the front surface 10a of the grinding target 10. As a result, the grinding target 10 can be intermittently pressed by at least one of the grindstones 22. Therefore, the peeling of the semiconductor substrate 12 and the layer 14 can be prevented by grinding, and the streaks and chipping formed on the front surface 10a of the grinding target 10 can be reduced. Therefore, the damage of the grinding target 10 can be reduced.

[0062] The width d is preferably, for example, 3.5 mm or more and 4.5 mm or less.

[0063] The inclination angle is preferably, for example, 30 or more and 45 or less. By setting the inclination angle to 30 or more and 45 or less, chipping on the front side surface 22B of the grindstone 22 due to an excessively acute angle can be prevented.

[0064] The angle x is preferably, for example, 15 or more and 25 or less. By setting the angle to 15 or more and 25 or less, the wheel 21 including the rotating front surface 21a including a diameter substantially the same as the diameter of the grinding target 10 can be applied.

[0065] The width p is preferably, for example, 1.0 mm or more and 2.0 mm or less. By setting the width to 1.0 mm or more and 2.0 mm or less, the number of the grindstones 22 can be increased while allocating a path (flow path) of the grinding fluid, and the grinding load per grindstone 22 can be dispersed.

[0066] The inclination width s is preferably, for example, 1.5 mm or more and 2.0 mm or less. By setting the inclination width to 1.5 mm or more and 2.0 mm or less, the angle T can be set to 60 or more and 75 or less. It should be understood that the angle T may vary based on factors such as the material properties of the grinding target 10, the rotational speed of the rotating front surface 21a, the applied grinding force, and the geometric configuration of the grindstone 22, including variations in the shape of the front side surface 22B. Additionally, modifications to the inclination width s, the slit ST, or the overall arrangement of the grindstones 22 may further influence the achievable range of the angle T beyond the specified values while maintaining effective grinding performance.

[0067] The grindstone 22 including the above-described shape can be formed, for example, by performing machining on a rectangular parallelepiped-shaped grindstone. The present embodiment is not limited thereto, and a commercially available grindstone that is pre-processed into a desired shape may be used as the grindstone 22.

[0068] In the grinding device and the grinding method using the grinding head according to the embodiment, damage to the grinding target can be prevented and damage to the grindstone can be prevented. Therefore, for example, it is possible to reduce the deterioration in yield caused by the bursting of a void generated during bonding, which is a problem in the film formation processing of 10 m or less of the grinding target, during grinding.

[0069] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.