Diamond grinding method

Abstract

To provide a diamond grinding method which can efficiently grind diamond.SOLUTION: A diamond grinding method includes: a metal bonding step 1 of relatively moving a cut surface of diamond and a metal material while bringing the metal material into contact with the cut surface of the diamond, and thereby bonding the metal material to the cut surface of the diamond; a laser beam irradiation step 2 of irradiating the cut surface of the diamond bonded with the metal material with a laser beam having a wavelength having permeability to the diamond and absorbency to the metal material, and thereby modifying the cut surface of the diamond bonded with the metal material; and a grinding step 3 of relatively grinding and feeding the cut surface of the diamond and the grinding member while bringing the grinding member into contact with the cut surface of the diamond, and thereby grinding and removing a modified region of the cut surface, after the laser beam irradiation step 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for grinding diamond.

Background Art

[0002] In the process of thinning and planarizing a workpiece, a grinding apparatus is used to perform grinding by bringing a grinding wheel into contact with the grinding surface of the workpiece held on a chuck table while rotating the chuck table and the grinding wheel relative to each other in a direction approaching each other while relatively grinding and feeding them (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when grinding a difficult-to-grind material such as a sapphire substrate or SiC substrate with a grinding apparatus, there is a problem that not only does it take a very long time to grind, but also the consumption of the grinding wheel is extremely large and uneconomical. In particular, since a diamond substrate has very poor grindability, the development of an efficient grinding method is desired.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a method for grinding diamond that can efficiently grind diamond.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the diamond grinding method of the present invention is characterized by comprising: a metal attachment step of adhering the metal material to the grinding surface of a diamond by bringing the metal material into contact with the grinding surface of the diamond and moving the grinding surface of the diamond and the metal material relatively together; a laser beam irradiation step of altering the grinding surface of the diamond to which the metal material is adhering by irradiating the grinding surface of the diamond to which the metal material is adhering with a laser beam of a wavelength that is transparent to the diamond and absorbent to the metal material; and a grinding step of grinding away the altered region of the grinding surface of the diamond after performing the laser beam irradiation step, by bringing a grinding member into contact with the grinding surface of the diamond and relatively feeding the grinding surface of the diamond and the grinding member together.

[0007] Furthermore, in the diamond grinding method of the present invention, the grinding member may be a metal material that is attached to the surface of the diamond to be ground.

[0008] Furthermore, in the diamond grinding method of the present invention, the metal material may include transition metals and rare earth elements.

[0009] Furthermore, in the diamond grinding method of the present invention, the metal attachment step may be performed with fine particles made of iron or carbon attached to at least one of the grinding surface of the diamond and the contact surface of the metal material with respect to the grinding surface. [Effects of the Invention]

[0010] The present invention allows for the efficient grinding of diamonds. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a flowchart showing the flow of a diamond grinding method according to an embodiment. [Figure 2]Figure 2 is a schematic perspective view illustrating an example of the diamond grinding method shown in Figure 1. [Figure 3] Figure 3 is a magnified cross-sectional view of a portion of the diamond wafer. [Figure 4] Figure 4 is a magnified cross-sectional view showing a portion of the diamond wafer after the metal deposition step shown in Figure 1. [Figure 5] Figure 5 is a magnified cross-sectional view showing a portion of the diamond wafer after the laser beam irradiation step shown in Figure 1. [Figure 6] Figure 6 is a magnified cross-sectional view showing a portion of the diamond wafer after the grinding step shown in Figure 1. [Figure 7] Figure 7 is a schematic diagram showing the flow of a diamond grinding method according to a modified example. [Modes for carrying out the invention]

[0012] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by those skilled in the art, and those that are substantially the same. Moreover, the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention.

[0013] [Embodiment] A diamond grinding method according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 is a flowchart showing the flow of the diamond grinding method according to the embodiment. As shown in Figure 1, the diamond grinding method of the embodiment comprises a metal attachment step 1, a laser beam irradiation step 2, and a grinding step 3, and the metal attachment step 1, laser beam irradiation step 2, and grinding step 3 are repeatedly performed until the grinding of the diamond is completed.

[0014] Figure 2 is a schematic perspective view showing an example of the diamond grinding method shown in Figure 1. Figure 3 is an enlarged cross-sectional view showing a part of the diamond wafer 10. In this embodiment, the diamond to be processed is a square-shaped diamond wafer 10 with a diamond substrate. As shown in Figure 3, the diamond wafer 10 has irregularities on the grinding surface 12 opposite to the device surface 11 on which the device is formed. In the diamond grinding method of this embodiment, the diamond wafer 10 is thinned and the grinding surface 12 is flattened by grinding the grinding surface 12 of the diamond wafer 10.

[0015] The diamond wafer 10 is held on the holding surface 21 of the wafer holding unit 20 shown in Figure 2 during the metal deposition step 1, laser beam irradiation step 2, and grinding step 3 shown in Figure 1. The wafer holding unit 20 is disc-shaped and rotatable around a vertical axis, and has the holding surface 21 on its lower side. The wafer holding unit 20 attracts and holds the device side 11 of a plurality (four in this embodiment) of diamond wafers 10 at evenly spaced positions around the axis on the holding surface 21.

[0016] A metal material holding unit 30 is positioned opposite a portion of the holding surface 21 of the wafer holding unit 20. Additionally, a laser beam irradiation unit (not shown) that irradiates a laser beam 40 is positioned opposite a portion of the holding surface 21 of the wafer holding unit 20.

[0017] The metal material holding unit 30 includes a base 31 that is vertical and rotatable around an axis parallel to the axis of the wafer holding unit 20, and a disc-shaped metal plate 32 mounted on the upper surface of the base 31. The contact surface 33, which is the upper surface of the metal plate 32, faces the grinding surface 12 of the diamond wafer 10 held by the wafer holding unit 20. The metal plate 32 is made of a metallic material. The metallic material includes, for example, iron (Fe), nickel (Ni), cobalt (Co), or alloys thereof, or carbon-containing alloys. Preferably, the metallic material further includes transition metals and rare earth elements.

[0018] The diamond wafer 10 held by the wafer holding unit 20 is subjected to the adhesion of the metal material by the metal material holding unit 30, the irradiation of the laser beam 40 by a laser beam irradiation unit (not shown), and the grinding by the metal material holding unit 30 in sequence and repeatedly by the rotation of the wafer holding unit 20 around the axis.

[0019] Hereinafter, each step will be described in detail. The metal adhesion step 1 is a step of adhering the metal material to the grinding surface 12 by moving the grinding surface 12 and the metal material relatively while bringing the metal material (in the embodiment, the metal plate 32) into contact with the grinding surface 12 of the diamond wafer 10.

[0020] The metal adhesion step 1 of the embodiment is performed on the diamond wafer 10 facing the metal material holding unit 30 among the plurality of diamond wafers 10 held on the device surface 11 side by the wafer holding unit 20. The metal material holding unit 30 adheres the metal material to the grinding surface 12 by bringing the contact surface 33 of the metal plate 32 into contact with the grinding surface 12 of the diamond wafer 10 while rotating around the axis. At this time, it is preferably performed in a state where fine particles made of gold or carbon are adhered to at least one of the grinding surface 12 and the contact surface 33.

[0021] FIG. 4 is an enlarged cross-sectional view showing a part of the diamond wafer 10 after the metal adhesion step 1 shown in FIG. 1. As shown in FIG. 4, due to the rubbing of the metal plate 32 made of the metal material against the grinding surface 12 having irregularities, the metal powder 34 of the metal material adheres to the convex portions of the grinding surface 12.

[0022] The diamond wafer 10, on which metal powder 34 is attached to the surface to be ground 12, is moved to a position facing a laser beam irradiation unit (not shown) by the rotation of the wafer holding unit 20 around its axis, and the laser beam irradiation step 2 is performed. The laser beam irradiation step 2 is a step in which the surface to be ground 12 of the diamond wafer 10, on which the metal powder 34 (metal material) is attached, is irradiated with a laser beam 40 to alter the surface to be ground 12 to which the metal powder 34 (metal material) is attached.

[0023] In the embodiment, laser beam irradiation step 2 is performed on one of a plurality of diamond wafers 10, the device surface 11 side of which is held by the wafer holding unit 20, and which faces a laser beam irradiation unit (not shown). The laser beam 40 is a laser beam with a wavelength that is transparent to diamond and absorbent to metallic materials, for example, a CO2 laser. In the embodiment, laser beam 40 is irradiated onto the grinding surface 12 of the diamond wafer 10 facing the laser beam irradiation unit (not shown). At this time, the defocus amount of the laser beam 40 is set so that the irradiation area covers the entire grinding surface 12.

[0024] Figure 5 is an enlarged cross-sectional view showing a portion of the diamond wafer 10 after the laser beam irradiation step 2 shown in Figure 1. The metal powder 34 that adhered to the grinding surface 12 by the metal adhesion step 1 (see Figure 4) is heated and melted by the irradiation of the laser beam 40, as shown in Figure 5, and incorporates carbon (C) from the protrusions of the grinding surface 12 to form a metal-carbon compound. That is, the portion of the grinding surface 12 to which the metal powder 34 adheres is altered (carbidized), and a brittle altered region 13 is formed. Note that if the metal material constituting the metal plate 32 contains rare earth elements such as cerium (Ce), the melting point of the metal is lowered, making it easier to form the altered region 13 by irradiation of the laser beam 40.

[0025] The diamond wafer 10, on which a modified region 13 has been formed on the surface 12 to be ground, is moved again to a position facing the metal material holding unit 30 by the rotation of the wafer holding unit 20 around its axis, and grinding step 3 is performed. That is, grinding step 3 is performed after the laser beam irradiation step 2 is performed. Grinding step 3 is a step in which the modified region 13 on the surface 12 to be ground is removed by grinding and feeding the surface 12 and the grinding member relatively while bringing the grinding member (in this embodiment, a metal plate 32) into contact with the surface 12 to be ground on the diamond wafer 10.

[0026] In this embodiment, grinding step 3 is performed on one of the diamond wafers 10, which is held by the wafer holding unit 20 with its device surface 11 side facing the metal material holding unit 30. The metal material holding unit 30 grinds the surface 12 by rotating around its axis and bringing the contact surface 33 of the metal plate 32 into contact with the surface 12 of the diamond wafer 10 to be ground, while feeding it in the grinding manner, thereby removing the altered region 13.

[0027] Figure 6 is an enlarged cross-sectional view showing a portion of the diamond wafer 10 after grinding step 3 shown in Figure 1. The altered region 13 formed on the grinding surface 12 by the laser beam irradiation step 2 (see Figure 5) is removed as shown in Figure 6 by grinding the grinding surface 12 by the metal material holding unit 30. Since the altered region 13 is more brittle than other areas of the diamond wafer 10, grinding of the convex portion of the grinding surface 12 including the altered region 13 is promoted, and wear of the grinding wheel can be suppressed. The diamond wafer 10 is thinned by grinding.

[0028] After the altered region 13 of the grinding surface 12 is removed by grinding, the diamond wafer 10 undergoes the metal adhesion step 1 again. That is, in this embodiment, both the metal material that comes into contact with the grinding surface 12 in the metal adhesion step 1 and the grinding member that grinds the grinding surface 12 in the grinding step 3 are metal plates 32. Therefore, the metal plate 32 grinds the grinding surface 12 to remove the altered region 13 and also adheres metal powder 34 (metal material) to the grinding surface 12.

[0029] As described above, in the diamond grinding method of this embodiment, a metallic material (metal powder 34) is attached to the grinding surface 12 of the diamond wafer 10, and this is reacted with the carbon on the grinding surface 12 by irradiation with a laser beam 40 to form a brittle altered region 13, thereby promoting grinding and suppressing wear of the grinding wheel. The altered region 13 is removed by grinding, but by performing the metal attachment step 1 and the laser beam irradiation step 2 again, the altered region 13 is formed again, and grinding is promoted. In this way, by repeatedly performing the metal attachment step 1, the laser beam irradiation step 2, and the grinding step 3 until the diamond wafer 10 is ground to a predetermined thickness, the grinding surface 12 can be efficiently flattened, that is, grinding can be performed at high speed while suppressing wear of the grinding wheel.

[0030] [Variation] In this embodiment, both the metal material that comes into contact with the surface to be ground 12 in the metal attachment step 1 and the grinding member that grinds the surface to be ground 12 in the grinding step 3 are metal plates 32. However, the grinding member used in the grinding step 3 may be a grinding wheel separate from the metal plate 32, which is made of a metal material. Figure 7 is a schematic diagram showing the flow of a diamond grinding method according to a modified example.

[0031] In the modified example shown in Figure 7, elements that are substantially the same as those in the embodiment shown in Figure 2, such as the diamond wafer 10, wafer holding unit 20, metal material holding unit 30, and laser beam 40, are denoted by the same reference numerals and their descriptions are omitted. In the modified example shown in Figure 7, the holding surface 21 of the wafer holding unit 20 faces upward, and the diamond wafer 10 is held in the wafer holding unit 20 with the grinding surface 12 facing upward.

[0032] In the modified version, the wafer holding unit 20 is useful when holding a single large diamond wafer 10. In the diamond grinding method of the embodiment, the wafer holding unit 20 rotates, causing multiple diamond wafers 10 held by the wafer holding unit 20 to move successively between the processing area of ​​the metal material holding unit 30 and the processing area of ​​the laser beam irradiation unit (not shown). In contrast, in the modified version, the wafer holding unit 20 transports the diamond wafer 10 between the processing area of ​​the metal material holding unit 30, the processing area of ​​the laser beam irradiation unit (not shown), and the processing area of ​​the grinding unit 50.

[0033] The grinding unit 50 includes a grinding wheel 51 attached to the lower end of a spindle (not shown), which is a rotating shaft member, and a grinding wheel 52 mounted on the lower surface of the grinding wheel 51. The grinding wheel 51 rotates on a rotation axis parallel to the axis of the wafer holding unit 20.

[0034] In the modified configuration, first, the wafer holding unit 20 transports the held diamond wafer 10 to the processing area below the metal material holding unit 30. Next, the metal adhesion step 1 is performed, and with the wafer holding unit rotating around its axis, the metal material holding unit 30 rotates around its axis and brings the contact surface 33 of the metal plate 32 into contact with the grinding surface 12 of the diamond wafer 10, thereby adhering the metal material to the grinding surface 12.

[0035] Next, the wafer holding unit 20 transports the diamond wafer 10, on which the metal powder 34 adheres to the surface 12 to be ground, to the processing area below the laser beam irradiation unit (not shown). Next, the laser beam irradiation step 2 is performed, in which the laser beam irradiation unit (not shown) irradiates the surface 12 of the diamond wafer 10, on which the metal powder 34 (metal material) adheres, with a laser beam 40, thereby altering the surface 12 to which the metal powder 34 (metal material) adheres, and forming an altered region 13.

[0036] Next, the wafer holding unit 20 transports the diamond wafer 10, on which a modified region 13 has been formed on the surface to be ground 12, to the processing area below the grinding unit 50. Then, grinding step 3 is performed, in which the grinding unit 50 rotates around its axis and brings the grinding wheel 52 into contact with the surface to be ground 12 of the diamond wafer 10, while relatively grinding and feeding the surface to be ground 12 and the grinding member. As a result, the grinding wheel 52 grinds away the modified region 13 of the surface to be ground 12.

[0037] Next, the wafer holding unit 20 transports the diamond wafer 10, from which the altered region 13 has been ground away, back to the processing area below the metal material holding unit 30, and performs the metal adhesion step 1 again. When performing the metal adhesion step 1 again, it is not necessary to completely remove the altered region 13 formed on the grinding surface 12 in grinding step 3; it is sufficient if it is removed before the diamond grinding is completed.

[0038] It should be noted that the present invention is not limited to the embodiments and modifications described above. That is, it can be implemented with various modifications without departing from the core of the present invention. For example, in the embodiments, the surface of the diamond wafer 10 opposite to the grinding surface 12 was designated as the "device surface 11 on which the device is formed," but in the present invention, the device does not necessarily have to be formed on the surface of the diamond wafer 10 opposite to the grinding surface 12. [Explanation of symbols]

[0039] 10 Diamond wafers (diamonds) 11 device surfaces 12 Surface to be ground 13. Alteration Area 20 Wafer holding units 21 Holding surface 30 Metal Material Holding Unit 31 base 32 Metal plate (metal material) 33 Contact surface 34 Metal powder 40 laser beams 50 grinding units 51 Grinding Wheel 52 grinding wheels

Claims

1. A method for grinding diamonds, A metal attachment step involves bringing a metal material into contact with the abrasive surface of a diamond and moving the abrasive surface of the diamond and the metal material relative to each other, thereby causing the metal material to adhere to the abrasive surface of the diamond. A laser beam irradiation step is performed to alter the surface of the diamond to be ground, to which the metal material is attached, by irradiating the surface of the diamond to be ground with a laser beam having a wavelength that is transparent to the diamond and absorbent to the metal material, The system includes a grinding step in which, after performing the laser beam irradiation step, the grinding member is brought into contact with the grinding surface of the diamond, and the grinding member and the grinding surface of the diamond are relatively fed together to grind away the altered region of the grinding surface. A method for grinding diamonds, characterized by the following features.

2. The grinding member is the metal material that is attached to the surface of the diamond to be ground. The diamond grinding method according to claim 1, characterized in that

3. The metallic material contains transition metals and rare earth elements. A diamond grinding method according to claim 1 or 2, characterized in that

4. The metal attachment step is performed with fine particles made of iron or carbon attached to at least one of the grinding surface of the diamond and the contact surface of the metal material with respect to the grinding surface. A diamond grinding method according to claim 1 or 2, characterized in that

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