Grinding head, grinding apparatus, and grinding method

Abstract

This suppresses damage to the workpiece during grinding. [Solution] A grinding head for grinding an object to be ground comprises a wheel having a rotating surface and a plurality of grinding wheels arranged in a ring on the rotating surface with respect to the axis of rotation of the rotating surface. Each of the plurality of grinding wheels has a first surface that can directly contact the object to be ground and a second surface that is inclined at an acute angle with respect to the direction of travel of the grinding wheel from the rotating surface to the first surface.

Description

Technical Field

[0001] Embodiments of the present invention relate to a grinding head, a grinding apparatus, and a grinding method.

Background Art

[0002] In recent years, when manufacturing semiconductor devices, it has been known to grind an object to be ground, such as a bonded substrate including a semiconductor substrate, using a grinding head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One of the problems to be solved by the present invention is to suppress damage to the object to be ground due to grinding.

Means for Solving the Problems

[0005] The grinding head according to the embodiment is a grinding head that grinds an object to be ground, and includes a wheel having a rotating surface, and a plurality of grinding wheels annularly arranged on the rotating surface around the rotation axis of the rotating surface. Each of the plurality of grinding wheels has a first surface that can directly contact the object to be ground, and a second surface that is inclined at an acute angle with respect to the advancing direction of the grinding wheel from the rotating surface to the first surface.

Brief Description of the Drawings

[0006] [Figure 1] It is a schematic diagram showing a configuration example of a grinding apparatus. [Figure 2] It is a schematic diagram for explaining an example of a conventional grinding method. [Figure 3] It is a schematic diagram for explaining an example of a conventional grinding method. [Figure 4] This is a schematic diagram illustrating an example of a grinding method according to an embodiment. [Figure 5] This is a schematic diagram illustrating an example of a grinding method according to an embodiment. [Figure 6] This is a schematic diagram illustrating an example of the three-dimensional shape of a grinding wheel. [Figure 7] This is a schematic diagram illustrating an example of the three-dimensional shape of a grinding wheel. [Figure 8] This is a schematic diagram illustrating an example of a grinding wheel shape design. [Modes for carrying out the invention]

[0007] The embodiments will be described below with reference to the drawings. The relationship between the thickness and planar dimensions of each component shown in the drawings, the ratio of the thicknesses of each component, etc., may differ from the actual product. Also, in the embodiments, substantially identical components are denoted by the same reference numerals and their descriptions are omitted as appropriate.

[0008] (Example of a grinding device configuration) Figure 1 is a schematic diagram showing an example of the configuration of a grinding apparatus. Figure 1 shows the grinding apparatus 100. Figure 1 further shows the X-axis, Y-axis, and Z-axis. The X-axis, Y-axis, and Z-axis intersect each other perpendicularly. The Z-axis is, for example, along the thickness direction of the workpiece 10 to be ground.

[0009] The grinding device 100 can grind the object to be ground 10. The grinding device 100 comprises a stage 1 and a grinding head 2.

[0010] Stage 1 has the function of rotating the workpiece 10 about a rotation axis AS1 in the Z-axis direction of Stage 1. Stage 1 has a surface (mounting surface) 1a on which the workpiece 10 is placed. The planar shape of surface 1a is, for example, circular. The X and Y axes extend in directions parallel to surface 1a, for example. The Z axis intersects surface 1a perpendicularly, for example. Surface 1a is rotatable about the rotation axis AS1. Stage 1 may be movable in the X, Y, and Z axis directions. Stage 1 may be driven by a drive device including, for example, a motor. Stage 1 may have a suction device that can hold the workpiece 10. An example of a suction device is a vacuum chuck.

[0011] An example of the object to be ground 10 is a substrate containing a semiconductor device in the process of being manufactured. The object to be ground 10 includes, for example, a semiconductor substrate 11, a semiconductor substrate 12, a layer 13 between the semiconductor substrate 11 and the semiconductor substrate 12, and a layer 14 between the semiconductor substrate 12 and the layer 13. However, the structure of the object to be ground 10 is not limited to this.

[0012] Each of the semiconductor substrates 11 and 12 is, for example, a silicon wafer.

[0013] Layer 13 is provided on the semiconductor substrate 11. Layer 13 includes, for example, a memory cell array in a semiconductor device such as a NAND flash memory.

[0014] Layer 14 is provided on the semiconductor substrate 11. Layer 14 has peripheral circuits, including CMOS circuits, in a semiconductor device such as a NAND flash memory. The surface of layer 14 is bonded to the surface of layer 13. This electrically connects the peripheral circuits and the memory cell array.

[0015] The grinding head 2 includes a wheel 21 and a grinding wheel 22.

[0016] The wheel 21 has a rotating surface 21a. The planar shape of the rotating surface 21a is, for example, circular. The rotating surface 21a is rotatable about a rotation axis AS2 in the Z-axis direction. When grinding the object to be ground 10, the rotating surface 21a is arranged to overlap, for example, the surface 10a of the object to be ground 10 in the Z-axis direction. Examples of the surface 10a include the surface (exposed surface) of the semiconductor substrate 12. The wheel 21 may be driven by a driving device including, for example, a motor.

[0017] The grinding wheel 22 can grind the object to be ground 10. The grinding head 2 has a plurality of grinding wheels 22. The plurality of grinding wheels 22 are provided on the rotating surface 21a and juxtaposed along the periphery of the rotating surface 21a. The plurality of grinding wheels 22 may be juxtaposed annularly on the rotating surface 21a about the rotation axis AS2, for example. The number of the plurality of grinding wheels 22 is not particularly limited.

[0018] The grinding head 2 has a function of pressing the grinding wheel 22 (the portion contacting the object to be ground 10) against the surface 10a for grinding. The grinding head 2 may be movable, for example, along each of the X-axis direction, the Y-axis direction, and the Z-axis direction. The grinding head 2 has a function of rotating the grinding wheel 22 about the rotation axis AS2, for example. The grinding head 2 may be driven by a driving device including, for example, a motor.

[0019] The stage 1 and the grinding head 2 may be controlled by, for example, a control device. The control device may be configured using hardware such as a processor. 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 out the operation program stored in the recording medium by the hardware.

[0020] (Grinding method) Next, an example of a grinding method using the grinding apparatus 100 will be described. First, the object to be ground 10 is placed on the surface 1a of the stage 1. Surface 1a is in contact with the opposite side of the surface 10a of the object to be ground 10 (the back surface (exposed surface) of the semiconductor substrate 11). The object to be ground 10 may be placed on surface 1a using a transport device such as a robot arm. The transport device may be controlled by the control device described above.

[0021] Next, while supplying a grinding fluid such as pure water to the grinding surface (surface 10a), the surface 10a is rotated in a first rotational direction R1 (for example, clockwise), and the grinding head 2 is moved in the Z-axis direction to bring the surface (grinding surface) of the grinding wheel 22 into contact with the surface 10a of the object to be ground 10, and the rotating surface 21a is rotated in a second rotational direction R2 (for example, counterclockwise), which is opposite to the first rotational direction. As a result, the object to be ground 10 is ground, for example, from the surface 10a. Note that the semiconductor substrate 12 may be removed by grinding the object to be ground 10. This makes the object to be ground 10 thinner.

[0022] Figures 2 and 3 are schematic diagrams illustrating an example of a conventional grinding method. Figure 2 is a schematic plan view showing the workpiece 10 and grinding head 2 during grinding. Figure 3 is a schematic cross-sectional view showing the workpiece 10 and grinding head 2 during grinding. The grinding head 2 has a plurality of grinding wheels 22. The plurality of grinding wheels 22 are arranged in an annular manner on the rotating surface 21a with the rotation axis AS2 of the rotating surface 21a as the center. Slits ST are formed between adjacent grinding wheels 22. The slits ST serve, for example, as paths for the flow of grinding fluid.

[0023] When the grinding wheel 22 is rectangular, the lower surface 22a of the grinding wheel 22 is positioned parallel to the rotating surface 21a and directly contacts the workpiece 10 to be ground. The front surface 22b of the grinding wheel 22 faces forward in the second rotation direction R2 of the rotating surface 21a (the direction of travel of the grinding wheel 22) and extends perpendicular to the rotating surface 21a from the rotating surface 21a to the front surface 22b. That is, the angle T formed by the lower surface 22a and the front surface 22b is 90 degrees.

[0024] When the grinding wheel 22 is rectangular, the contact area between the lower surface 22a of the grinding wheel 22 and the workpiece 10 to be ground is small, and during grinding, the periphery of the workpiece intermittently does not come into direct contact with any of the grinding wheels 22. For example, if there is an unbonded portion between layer 13 and layer 14, the lower surface 22a or front surface 22b of the grinding wheel 22 will come into contact with the unbonded portion in the slit ST between adjacent grinding wheels 22, causing the semiconductor substrate 12 and layer 13 to peel off from layer 14 and be lifted, as shown in Figure 3. This can cause damage such as malfunction of the semiconductor device being manufactured due to damage to the workpiece 10.

[0025] In contrast, the grinding method of this embodiment grinds the object to be ground 10 using a grinding head 2 having a grinding wheel 22 having a three-dimensional shape different from that of a rectangular parallelepiped. Figures 4 and 5 are schematic diagrams illustrating an example of the grinding method of this embodiment. Figure 4 is a schematic plan view showing the object to be ground 10 and the grinding head 2 during grinding. Figure 5 is a schematic cross-sectional view showing the object to be ground 10 and the grinding head 2 during grinding.

[0026] In the grinding method of this embodiment, the lower surface 22a of the grinding wheel 22 is provided parallel to the rotating surface 21a and is in direct contact with the object to be ground 10. The front surface 22b of the grinding wheel 22 faces the front of the grinding wheel 22 in the second rotation direction R2 of the rotating surface 21a (the direction of travel of the grinding wheel 22) and extends from the rotating surface 21a to the front surface 22b at an acute angle with respect to the rotating surface 21a. The angle T formed by the lower surface 22a and the front surface 22b is preferably, for example, 60° or more and 75° or less.

[0027] In the second rotation direction R2 of the rotating surface 21a (the direction of travel of the grinding wheel 22), the front surface 22B is inclined at an acute angle with respect to the rotating surface 21a, thereby increasing the contact area between the grinding wheel 22 and the workpiece 10 compared to when the grinding wheel 22 is rectangular. This allows the force applied to the workpiece 10 when the grinding wheel 22 comes into contact with it to be distributed, thereby suppressing, for example, the peeling of the semiconductor substrate 12 and layer 14. Thus, damage to the workpiece 10 due to grinding can be suppressed.

[0028] Furthermore, it is preferable that the slit ST extends so as to be inclined with respect to the radial direction of the rotating surface 21a. In other words, it is preferable that the slit ST extends in a direction intersecting the radial direction of the rotating surface 21a. This ensures that at least one of the multiple grinding wheels 22 is always in direct contact with the surface 10a of the object to be ground 10, so that at least one of the grinding wheels 22 can intermittently press down on the object to be ground 10. Therefore, delamination of the semiconductor substrate 12 and layer 14 due to grinding can be suppressed, and streaks and chips formed on the surface 10a of the object to be ground 10 can be reduced. Consequently, damage to the object to be ground 10 can be suppressed. In addition, by inclining the slit ST with respect to the radial direction of the rotating surface 21a, the shavings and grinding fluid generated during grinding can be easily discharged from the surface 10a of the object to be ground 10.

[0029] In the embodiment, the three-dimensional shape of the grinding wheel 22 is preferably appropriately designed to be suitable for effectively suppressing damage to the workpiece 10 as described above. Figures 6 and 7 are schematic diagrams illustrating examples of the three-dimensional shape of the grinding wheel. Figures 6 and 7 schematically show the bottom surface 22A, the front side surface 22B, the top surface 22C, the rear side surface 22D, the inner side surface 22E, and the outer side surface 22F of the grinding wheel 22.

[0030] The lower surface 22A is the lower surface of the grinding wheel 22 when viewed from above and downward in a direction perpendicular to the direction of movement of the grinding wheel 22 (the thickness direction of the grinding wheel 22). The lower surface 22A faces the underside of the grinding wheel 22 in the thickness direction of the grinding wheel 22. The lower surface 22A can directly contact the surface 10a of the workpiece 10 to be ground and corresponds to the lower surface 22a in Figure 5. The planar shape of the lower surface 22A has a pentagonal shape connecting vertices A1, A2, A3, A4, and A5. This indicates that the front surface 22B is inclined at an acute angle with respect to the rotating surface 21a.

[0031] The lower surface 22A has edges A1-A2 connecting vertices A1 and A2, edges A2-A3 connecting vertices A2 and A3, edges A3-A4 connecting vertices A3 and A4, edges A4-A5 connecting vertices A4 and A5, and edges A5-A1 connecting vertices A5 and A1. Edges A1-A2 face the front of the grinding wheel 22 in the direction of the grinding wheel's movement and are inclined at an obtuse angle with respect to edges A2-A3. Edges A2-A3 face the front of the grinding wheel 22 in the direction of the grinding wheel's movement and are inclined with respect to the radial direction of the rotating surface 21a, as well as at an obtuse angle with respect to edges A3-A4. Edges A3-A4 face the inside of the grinding wheel 22 (towards the rotation axis AS2) in the direction of the grinding wheel's movement. Sides A4-A5 are positioned opposite to sides A2-A3 and are inclined at an acute angle to sides A3-A4. Sides A4-A5 face the rear of the grinding wheel 22 in the direction of the grinding wheel 22's movement and extend parallel to sides A2-A3. Sides A5-A1 face the outside of the grinding wheel 22 in the direction of the grinding wheel 22's movement, are positioned opposite to sides A3-A4, and extend parallel to sides A3-A4. The angle between sides A1-A2 and sides A5-A1 is, for example, 90°. The angle between sides A2-A3 and sides A3-A4 is the same as the angle between sides A4-A5 and sides A5-A1.

[0032] The front surface 22B is the front surface of the grinding wheel 22 when viewed from the front to the rear of the grinding wheel 22 in the direction of the grinding wheel 22's movement. The front surface 22B faces the front of the grinding wheel 22 in the direction of the grinding wheel 22's movement. At least a portion of the front surface 22B can directly contact the surface 10a of the workpiece 10 to be ground, and corresponds to the front surface 22b in Figure 5. The planar shape of the front surface 22B has the shape of a rectangle connecting vertices B1, B2, B3, and B4.

[0033] The front surface 22B has edges B1-B2 connecting vertices B1 and B2, edges B2-B3 connecting vertices B2 and B3, edges B3-B4 connecting vertices B3 and B4, and edges B4-B1 connecting vertices B4 and B1. Edges B1-B2 face the outside of the grinding wheel 22 in the direction of the grinding wheel 22's movement and extend perpendicularly to edges B2-B3 and B4-B1. Edges B2-B3 are shorter than edges B1-B4 and face the underside of the grinding wheel 22 in the thickness direction of the grinding wheel 22. Edges B3-B4 face the inside of the grinding wheel 22 in the direction of the grinding wheel 22's movement, inclined at an obtuse angle with respect to edges B2-B3 and at an acute angle with respect to edges B4-B1. Sides B4-B1 are positioned opposite to sides B2-B3, extend parallel to sides B2-B3, and face the upper side of the grinding wheel 22 in the thickness direction of the grinding wheel 22.

[0034] The upper surface 22C is the upper surface of the grinding wheel 22 when viewed from above to below in the thickness direction of the grinding wheel 22. The upper surface 22C faces the upper side of the grinding wheel 22 in the thickness direction of the grinding wheel 22. The upper surface 22C is located on the opposite side of the lower surface 22A and is fixed to the rotating surface 21a. The planar shape of the upper surface 22C is a pentagon formed by connecting vertices C1, C2, C3, C4, and C5. This indicates that the rear surface 22D is inclined at an obtuse angle with respect to the rotating surface 21a. Vertex C2 is in the same position as vertex B4.

[0035] The upper surface 22C has edges C1-C2 connecting vertices C1 and C2, edges C2-C3 connecting vertices C2 and C3, edges C3-C4 connecting vertices C3 and C4, edges C4-C5 connecting vertices C4 and C5, and edges C5-C1 connecting vertices C5 and C1. Edges C1-C2 face the front of the grinding wheel 22 in the direction of movement of the grinding wheel 22 and are inclined at an acute angle with respect to edges C2-C3. Edges C2-C3 face the inside of the grinding wheel 22 in the direction of movement of the grinding wheel 22. Edges C3-C4 face the rear of the grinding wheel 22 in the direction of movement of the grinding wheel 22, are positioned opposite to edges C1-C2, extend parallel to edges C1-C2, and are inclined at an obtuse angle with respect to edges C2-C3. Sides C4-C5 face the rear of the grinding wheel 22 in the direction of the grinding wheel 22's movement and are inclined at an obtuse angle with respect to sides C3-C4. Sides C5-C1 face the outside of the grinding wheel 22 in the direction of the grinding wheel 22's movement, are positioned opposite to sides C2-C3, and extend parallel to sides C2-C3. The angle formed by sides C4-C5 and C5-C1 is, for example, 90°. The angle formed by sides C1-C2 and C5-C1 is the same as the angle formed by sides C2-C3 and C3-C4.

[0036] The rear surface 22D is the rear surface of the grinding wheel 22 when viewed from the front to the rear of the grinding wheel 22 in the direction of the grinding wheel 22's movement. The rear surface 22D faces the rear of the grinding wheel 22 in the direction of the grinding wheel 22's movement. At least a portion of the rear surface 22D can directly contact the surface 10a of the workpiece 10 to be ground. The planar shape of the rear surface 22D is a quadrilateral shape formed by connecting vertices D1, D2, D3, and D4.

[0037] The rear side surface 22D has edges D1-D2 connecting vertices D1 and D2, edges D2-D3 connecting vertices D2 and D3, edges D3-D4 connecting vertices D3 and D4, and edges D4-D1 connecting vertices D4 and D1. Edges D1-D2 face the inside of the grinding wheel 22 in the direction of the grinding wheel 22's movement and are inclined at an acute angle with respect to edges D2-D3. Edges D2-D3 are positioned opposite to edges D4-D1, extend parallel to edges D4-D1, and face the underside of the grinding wheel 22 in the thickness direction of the grinding wheel 22. Edges D3-D4 face the outside of the grinding wheel 22 in the direction of the grinding wheel 22's movement and extend perpendicular to edges D2-D3 and D4-D1. Edges D4-D1 are positioned opposite to edges D2-D3, extend parallel to edges D2-D3, and face the upper side of the grinding wheel 22 in the thickness direction of the grinding wheel 22. Vertex D2 is in the same position as vertex A4.

[0038] The inner surface 22E is the inner surface when viewed from the inside to the outside of the grinding wheel 22 in directions perpendicular to the thickness direction and the direction of travel of the grinding wheel 22. The inner surface 22E faces the inside of the grinding wheel 22 in the direction of travel of the grinding wheel 22. The planar shape of the inner surface 22E is a quadrilateral including vertices E1, E2, E3, and E4. Furthermore, the shape of the grinding wheel 22 including the inner surface 22E when viewed from the inside can be considered a parallelogram. The inner surface 22E has edges E1-E2 connecting vertices E1 and E2, edges E2-E3 connecting vertices E2 and E3, edges E3-E4 connecting vertices E3 and E4, and edges E4-E1 connecting vertices E4 and E1. Vertex E1 is in the same position as vertices B4 and C2. Vertex E2 is in the same position as vertex A3. Vertex E3 is in the same position as vertices A4 and D2. Vertex E4 is in the same position as vertex C3.

[0039] Sides E1-E2 face the front side of the grinding wheel 22 in the direction of movement of the grinding wheel 22, extend parallel to E3-E4, and extend perpendicular to sides E2-E3 and E4-E1. Sides E2-E3 face the underside of the grinding wheel 22 in the thickness direction of the grinding wheel 22. Sides E3-E4 face the rear side of the grinding wheel 22 in the direction of movement of the grinding wheel 22, and extend perpendicular to sides E2-E3 and E4-E1. Side E4-E1 faces the upper side of the grinding wheel 22 in the thickness direction of the grinding wheel 22.

[0040] The outer surface 22F is the outer surface when viewed from the outside to the inside of the grinding wheel 22 in directions perpendicular to the thickness direction and the direction of travel of the grinding wheel 22. The outer surface 22F faces the outside of the grinding wheel 22 in the direction of travel of the grinding wheel 22. The planar shape of the outer surface 22F is a quadrilateral including vertices F1, F2, F3, and F4. Furthermore, the shape of the grinding wheel 22 including the outer surface 22F when viewed from the outside can be considered a parallelogram. The outer surface 22F has edges F1-F2 connecting vertices F1 and F2, edges F2-F3 connecting vertices F2 and F3, edges F3-F4 connecting vertices F3 and F4, and edges F4-F1 connecting vertices F4 and F1. Vertex F1 is in the same position as vertices C5 and D4. Vertex F2 is in the same position as vertex A5. Vertex F3 is in the same position as vertices A1 and B2. Vertex F4 is in the same position as vertex C1.

[0041] Sides F1-F2 face the rear side of the grinding wheel 22 in the direction of the grinding wheel 22's movement, extend parallel to F3-F4, and extend perpendicular to sides F2-F3 and F4-F1. Sides F2-F3 face the underside of the grinding wheel 22 in the thickness direction of the grinding wheel 22. Sides F3-F4 face the front side of the grinding wheel 22 in the direction of the grinding wheel 22's movement, and extend perpendicular to sides F2-F3 and F4-F1. Side F4-F1 faces the upper side of the grinding wheel 22 in the thickness direction of the grinding wheel 22.

[0042] The grinding wheel 22 shown in Figures 6 and 7 may further have a surface connecting vertices C2, B3, and A3 (C2-B3-A3), a surface connecting vertices C3, A4, and D1 (C3-A4-D1), a surface connecting vertices C1, B1, and E1 (C1-B1-E1), a surface connecting vertices A4, A5, and D3 (A4-A5-D3), a surface connecting vertices C5, D3, and A5 (C5-D3-A5), and a surface connecting vertices C1, A1, and B1 (C1-A1-B1).

[0043] The surface (C2-B3-A3) faces the front of the grinding wheel 22 in the direction of the grinding wheel 22's movement. The surface (C2-B3-A3) connects the bottom surface 22A, the front side surface 22B, and the inner side surface 22E. The planar shape of the surface (C2-B3-A3) is a triangle formed by connecting vertices C2, B3, and A3. The surface (C2-B3-A3) has edges C2-B3 connecting vertices C2 and B3, edges B3-A3 connecting vertices B3 and A3, and edges A3-C2 connecting vertices A3 and C2. Edges C2-B3 face the front side of the grinding wheel 22 in the direction of the grinding wheel 22's movement. Edges B3-A3 face the front and bottom sides of the grinding wheel 22 in the direction of the grinding wheel 22's movement. Sides A3-C2 face the front side of the grinding wheel 22 in the direction of the grinding wheel 22's movement. The surface (C2-B3-A3) is inclined at an acute angle with respect to the rotating surface 21a. The surface (C2-B3-A3) is inclined at an obtuse angle with respect to the front surface 22B and the inner surface 22E. The surface (C2-B3-A3) does not need to be in direct contact with the surface 10a of the workpiece 10 to be ground.

[0044] The surface (C3-A4-D1) connects the top surface 22C, the rear surface 22D, and the inner surface 22E. The planar shape of the surface (C3-A4-D1) is a triangle containing vertices C3, A4, and D1. The surface (C3-A4-D1) has edges C3-A4 connecting vertices C3 and A4, edges A4-D1 connecting vertices A4 and D1, and edges D1-C3 connecting vertices D1 and C3. Edges C3-A4 face the inside of the grinding wheel 22 in the direction of the grinding wheel's movement. Edges A4-D1 face the rear side of the grinding wheel 22 in the direction of the grinding wheel's movement. Edges D1-C3 face the top side of the grinding wheel 22 in the thickness direction of the grinding wheel 22. The surface (C3-A4-D1) is inclined at an obtuse angle with respect to the rotating surface 21a. The surface (C3-A4-D1) is inclined at an obtuse angle with respect to the rear surface 22D and the inner surface 22E. The surface (C3-A4-D1) does not need to be in direct contact with the rotating surface 21a.

[0045] The surface (C1-B1-E1) connects the front surface 22B, the top surface 22C, and the outer surface 22F. The planar shape of the surface (C1-B1-E1) is a triangle containing vertices C1, B1, and E1. The surface (C1-B1-E1) has edges C1-B1 connecting vertices C1 and B1, edges B1-E1 connecting vertices B1 and E1, and edges E1-C1 connecting vertices E1 and C1. Edges C1-B1 face the outside of the grinding wheel 22 in the direction of movement of the grinding wheel 22. Edges B1-E1 face the front of the grinding wheel 22 in the direction of movement of the grinding wheel 22. Edges E1-C1 face the top of the grinding wheel 22 in the direction of movement of the grinding wheel 22. The surface (C1-B1-E1) is inclined at an obtuse angle with respect to the rotating surface 21a. The surface (C1-B1-E1) is inclined at an obtuse angle with respect to the front surface 22B, the top surface 22C, and the inner surface 22E. The surface (C1-B1-E1) does not have to be in direct contact with the rotating surface 21a.

[0046] The surface (A4-A5-D3) connects the bottom surface 22A and the rear side surface 22D. The planar shape of the surface (A4-A5-D3) is a triangle formed by connecting vertices A4, A5, and D3. The surface (A4-A5-D3) has sides A4-A5, sides A5-D3 connecting vertices A5 and D3, and sides D3-A4 connecting vertices D3 and A4. Sides A5-D3 face the outside of the grinding wheel 22 in the direction of the grinding wheel 22's movement. Sides D3-A4 face the rear of the grinding wheel 22 in the direction of the grinding wheel 22's movement. The surface (A4-A5-D3) is inclined at an acute angle with respect to the rotating surface 21a. The surface (A4-A5-D3) is inclined at an obtuse angle with respect to the bottom surface 22A, the rear side surface 22D, and 22E. The surfaces (A4-A5-D3) do not need to be in direct contact with the surface 10a of the object to be ground 10.

[0047] The surface (C1-A1-B1) connects the front surface 22B and the outer surface 22F. The planar shape of the surface (C1-A1-B1) is a triangle formed by connecting vertices C1, A1, and B1. The surface (C1-A1-B1) has edges C1-A1 connecting vertices C1 and A1, edges A1-B1 connecting vertices A1 and B1, and edges B1-C1 connecting vertices B1 and C1. Edges C1-A1 face the outside of the grinding wheel 22 in the direction of movement of the grinding wheel 22. Edges A1-B1 face the front of the grinding wheel 22 in the direction of movement of the grinding wheel 22. Edges B1-C1 face the outside of the grinding wheel 22 in the direction of movement of the grinding wheel 22. The surface (C1-A1-B1) is inclined at an acute angle with respect to the rotating surface 21a. The surface (C1-A1-B1) is inclined at an obtuse angle with respect to the lower surface 22A, the rear side surface 22D, and 22E. The surface (C1-A1-B1) does not need to be in direct contact with the surface 10a of the workpiece 10 to be ground.

[0048] When arranging multiple grinding wheels 22 having the shapes shown in Figures 6 and 7, it is preferable that the shapes of the grinding wheels 22 be further designed as follows. Figure 8 is a schematic diagram illustrating an example of the design of the shape of the grinding wheel 22. Figure 8 shows the lower surfaces 22A of each of two adjacent grinding wheels 22.

[0049] Preferably, the width d of the grinding wheel 22, the inclination width s of the front surface 22B, the inclination angle θ of the slit ST between adjacent grinding wheels 22 with respect to the straight line L1 along the radial direction of the rotating surface 21a, the angle x of the angle formed by the tangent L4 of the trajectory L2 passing through the intersection point CP of the trajectory L2 drawn by the outer surface 22F of the grinding wheel 22 when the rotating surface 21a rotates and the periphery L3 of the object to be ground 10, and the tangent L5 of the periphery L3 of the object to be ground 10 passing through the intersection point CP, and the width p of the slit ST satisfy the following equation (1). The width d can be defined, for example, by the length between sides A3-A4 and sides A5-A1. The inclination width s of the grinding wheel 22 can be defined, for example, by the length of the straight line A1-A6 connecting the intersection point A6 of sides A2-A3 and sides A1-A5 when sides A2-A3 and sides A1-A5 are extended, and the vertex A1. The straight line L1 passes through the axis of rotation AS2 on the rotating surface 21a. The inclination angle θ can be defined, for example, by the angle formed by L1 and sides A4-A5 of the grinding wheel 22. The angle x can be defined by the inclination angle of the tangent line L5 with respect to the tangent line L4. The width p can be defined, for example, by the maximum length (maximum width of the slit ST) between sides A4-A5 of the front grinding wheel 22 and sides A2-A3 of the rear grinding wheel 22 in two adjacent grinding wheels 22.

number

[0050] Here, we will explain the basis for deriving equation (1). Equation (1) can be calculated, for example, as follows. First, the distance l1 from line L1 to vertex A4 is expressed by equation (2).

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[0051] Furthermore, the distance l2 from edge A3-A4 to vertex A2 is expressed by equation (3).

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[0052] From equation (3), when the tangent line L5 lies on vertex A2, the distance l3 from side A1-A2 to the intersection point P1 of the tangent line L5 and side A3-A4 is given by equation (4). Here, the intersection point P1 is the point where the workpiece 10 to be ground comes into contact with the grinding wheel 22 behind it, and the workpiece 10 intersects with side A3-A4.

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[0053] Therefore, the distance from the straight line L1 to the intersection point P1 is the sum of the width p, the inclination width s, and the distance l3 of the slit ST, as shown in Figure 8. If the intersection point P1 is in front of the vertex A4 of the front grinding wheel 22, then either the front grinding wheel 22 or the rear grinding wheel 22 can maintain contact with the workpiece 10, and it is preferable that equation (5) is satisfied. Equation (1) can be derived from equations (2), (4), and (5).

number

[0054] By satisfying equation (1), it is possible to maintain a state in which at least one of the multiple grinding wheels 22 is always in direct contact with the surface 10a of the object to be ground 10. This allows at least one of the grinding wheels 22 to intermittently press down on the object to be ground 10. Therefore, delamination of the semiconductor substrate 12 and layer 14 due to grinding can be suppressed, and streaks and chips formed on the surface 10a of the object to be ground 10 can be reduced. Consequently, damage to the object to be ground 10 can be suppressed.

[0055] The width d is preferably, for example, 3.5 mm or more and 4.5 mm or less.

[0056] The inclination angle θ is preferably, for example, 30° to 45°. By setting it to 30° to 45°, chipping due to excessive sharpening of the front surface 22B of the grinding wheel 22 can be suppressed.

[0057] The angle x is preferably, for example, 15° to 25°. By setting the angle to 15° to 25°, a wheel 21 having a rotating surface 21a with a diameter similar to that of the workpiece 10 can be applied.

[0058] 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, it is possible to increase the number of grinding wheels 22 while ensuring a path (flow channel) for the grinding fluid, thereby distributing the grinding load per grinding wheel 22.

[0059] The inclination width s is preferably, for example, 1.5 mm or more and 2.0 mm or less. By setting it to 1.5 mm or more and 2.0 mm or less, the angle T can be made 60° or more and 75° or less.

[0060] A grinding wheel 22 having the shape described above can be formed, for example, by machining a rectangular parallelepiped grinding wheel. However, it is not limited to this, and a commercially available grinding wheel that has been pre-machined into a desired shape may also be used as the grinding wheel 22.

[0061] The grinding apparatus and grinding method using the grinding head of the embodiment can suppress damage to the workpiece being ground, as well as damage to the grinding wheel. Therefore, for example, it is possible to suppress the deterioration of yield caused by voids generated during bonding bursting during grinding, which is a problem in thin-film processing of workpieces with a thickness of 10 μm or less.

[0062] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0063] 1...Stage, 1a...Surface, 2...Grinding head, 2a...Grinding surface, 10...Object to be ground, 10a...Surface, 11...Semiconductor substrate, 12...Semiconductor substrate, 13...Layer, 14...Layer, 21...Wheel, 21a...Rotating surface, 22...Grinding wheel, 22A...Bottom surface, 22B...Front side, 22C...Top surface, 22D...Rear side, 22E...Inner side, 22F...Outer side, 22a...Bottom, 22b...Front side, 100...Grinding device.

Claims

1. A grinding head for grinding an object to be ground, A wheel having a rotating surface, A plurality of grinding wheels are arranged in a ring on the rotating surface with respect to the axis of rotation of the rotating surface, It is equipped with, Each of the aforementioned multiple grinding wheels is A first surface that can directly contact the object to be ground, A second surface that is inclined at an acute angle with respect to the direction of movement of the grinding wheel from the rotating surface to the first surface, Having, Grinding head.

2. A grinding head for grinding an object to be ground, A wheel having a rotating surface, A plurality of grinding wheels are arranged in a ring on the rotating surface with respect to the axis of rotation of the rotating surface, It is equipped with, Each of the aforementioned multiple grinding wheels is A first surface that can directly contact the object to be ground, A second surface that is inclined from the rotating surface to the first surface at an angle of inclination of 60° to 75° with respect to the direction of travel of the grinding wheel, It has, The width d of the grinding wheel, the inclination width s of the second surface, the inclination angle θ of the slit between adjacent grinding wheels with respect to the first straight line along the radial direction of the rotating surface, the angle x of the first tangent to the trajectory passing through the intersection point of the trajectory traced by the outer surface of the grinding wheel when the rotating surface rotates and the periphery of the object to be ground, and the angle x of the angle formed by the first tangent to the trajectory passing through the intersection point and the second tangent to the periphery of the object to be ground passing through the intersection point, and the width p of the slit are, The following equation (1) is satisfied: [Math 1] Grinding head.

3. A grinding head for grinding an object to be ground, A wheel having a rotating surface, A plurality of grinding wheels are arranged in a ring on the rotating surface with respect to the axis of rotation of the rotating surface, It is equipped with, Each of the aforementioned multiple grinding wheels is A first surface that can come into contact with the object to be ground, A second surface extending from the rotating surface to the first surface, It has, The planar shape of the first surface is a pentagon, The slit between adjacent grinding wheels extends along a direction intersecting the radial direction of the rotating surface. Grinding head.

4. The object to be ground is, A first semiconductor substrate and A second semiconductor substrate, A first layer between the first semiconductor substrate and the second semiconductor substrate, A second layer is provided between the first layer and the second semiconductor substrate and is bonded to the first layer, It has, The first surface is capable of direct contact with the surface of the second semiconductor substrate. A grinding head according to any one of claims 1 to 3.

5. A grinding head according to any one of claims 1 to 3, A stage on which the object to be ground is placed, Equipped with, Grinding device.

6. The first surface of the grinding wheel in the grinding head according to any one of claims 1 to 3 is brought into direct contact with the object to be ground, and the rotating surface is rotated to grind the object to be ground. Grinding method.

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