Grinding apparatus and method

Abstract

To provide a grinding wheel that enables the extended use of a grinding stone for grinding a diamond wafer.SOLUTION: A grinding wheel 21 for grinding a workpiece W includes grindstones 24 that at least include diamond abrasive grains 26, a grinding aid 27 composed of pure iron, and a bond agent 28.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a grinding device used when grinding a diamond wafer. Ruken grinding device and methods and is related thereto.

Background Art

[0002] In the semiconductor manufacturing field, as a device for thinly and flatly grinding a semiconductor wafer, a grinding device is known which presses the grindstone of a rotating grinding wheel against the semiconductor wafer to grind the semiconductor wafer.

[0003] Patent Document 1 discloses a cup-shaped grinding grindstone provided with a resin-bonded grindstone using diamond abrasive grains.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when grinding a semiconductor wafer made of diamond (hereinafter referred to as "diamond wafer") with a grindstone made of diamond abrasive grains, since diamonds come into contact with each other, there is a problem that the grindstone is easily worn and the device cost is high.

[0006] Therefore, a technical problem to be solved arises in order to use the grindstone for grinding a diamond wafer over a long period of time, and the present invention aims to solve this problem.

Means for Solving the Problems

[0007] To achieve the above objective, the grinding apparatus according to the present invention is a grinding apparatus comprising a grinding wheel for grinding a diamond wafer, wherein the grinding wheel comprises a grinding stone containing at least abrasive grains, a grinding aid made of pure iron, and a bonding agent, and when the grinding stone grinds the diamond wafer, the frictional heat generated when the grinding stone cuts into the diamond wafer causes carbon atoms contained in the diamond wafer to be incorporated into the pure iron contained in the grinding stone. It includes a control unit that controls it in this way. .

[0008] Furthermore, in order to achieve the above objective, the grinding according to the present invention method teeth, A grinding method for grinding a diamond wafer using a grinding wheel, wherein the grinding wheel comprises a grinding stone containing at least abrasive grains, a grinding aid made of pure iron, and a bonding agent, and when the grinding stone grinds the diamond wafer, the frictional heat generated when the grinding stone cuts into the diamond wafer causes carbon atoms contained in the diamond wafer to be incorporated into the pure iron contained in the grinding stone. . [Effects of the Invention]

[0009] The present invention allows for the long-term use of a grinding wheel for grinding diamond wafers. [Brief explanation of the drawing]

[0010] [Figure 1] A front view showing a grinding device according to one embodiment of the present invention. [Figure 2] A perspective view showing the structure of a grinding wheel. [Figure 3] A schematic diagram and a partially enlarged view showing the workpiece being ground. [Figure 4] A schematic diagram showing the state in which carbon atoms of the workpiece are in solid solution with iron atoms of the grinding wheel. [Figure 5] A schematic diagram illustrating the grinding process of a workpiece whose surface has become brittle. [Modes for carrying out the invention]

[0011] One embodiment of the present invention will be described with reference to the drawings. In the following, when referring to the number, numerical values, quantities, ranges, etc., of components, unless specifically indicated or clearly limited to a particular number in principle, the number is not limited to that particular number and may be greater than or less than that number.

[0012] When referring to the shape, positional relationship, etc. of components, etc., unless otherwise specifically stated or when it is considered not to be so in principle, it includes those that are substantially approximated or similar to such shapes, etc.

[0013] Also, the drawings may be exaggerated, such as by enlarging characteristic parts for easy understanding of the features, and the dimensional ratios of components, etc. are not necessarily the same as in reality. Also, in sectional views, in order to make the sectional structure of components easy to understand, the hatching of some components may be omitted.

[0014] The grinding device 1 shown in FIG. 1 is for thinly and flatly grinding a workpiece W. The workpiece W is a diamond wafer made of diamond. The grinding device 1 includes a grinding means 2 and a chuck table 3.

[0015] The grinding means 2 includes a grinding wheel 21, a grinding wheel spindle 22, and a spindle feed mechanism 23.

[0016] The grinding wheel 21 has a grinding surface 21a on its lower surface for grinding the workpiece W. The grinding wheel 21 is a cup-shaped grinding wheel and is attached to the lower end of the grinding wheel spindle 22. The grinding wheel spindle 22 is configured to rotationally drive the grinding wheel 21 around the rotation axis 2a.

[0017] The spindle feed mechanism 23 raises and lowers the grinding wheel spindle 22 in the vertical direction. The spindle feed mechanism 23 has a known configuration and is composed of, for example, a plurality of linear guides for guiding the moving direction of the grinding wheel spindle 22 and a ball screw slider mechanism for raising and lowering the grinding wheel spindle 22. The spindle feed mechanism 23 is interposed between the grinding wheel spindle 22 and the column 29.

[0018] As shown in Fig. 2, the grinding wheel 21 includes a plurality of grinding stones 24 formed in a segmental shape, and a base 25 that embeds at least a part of these grinding stones 24 in an annular groove (not shown) to hold the grinding stones 24 at a predetermined interval. The base 25 is fastened to the grinding stone spindle 22 via bolts (not shown).

[0019] The grinding stone 24 includes at least diamond abrasive grains 26, granular grinding aids 27 made of pure iron, and a bonding agent 28. The pure iron used for the grinding aids 27 has a metal structure of α-iron (ferrite) and exhibits a crystal structure of a body-centered cubic lattice in the temperature range during the process in which the grinding stone 24 cuts into the workpiece W.

[0020] The grinding stone 24 is formed by sintering a molded product obtained by kneading diamond abrasive grains 26 and grinding aids 27 at a predetermined ratio and molding them into a predetermined shape with a bonding agent 28. The mixing ratio of the diamond abrasive grains 26 and the grinding aids 27 is set to, for example, 50% by weight each. The particle size of the diamond abrasive grains 26 is set to, for example, 6 to 12 μm or 15 to 25 μm, but can be arbitrarily adjusted according to the type of the workpiece W and the processing conditions. The hard abrasive grains for grinding the workpiece W are not limited to the diamond abrasive grains 26, and may be, for example, cubic boron nitride or the like.

[0021] The chuck table 3 includes a chuck spindle 31. The chuck spindle 31 is configured to be rotationally driven around the rotation axis 3a.

[0022] An adsorbent 32 made of a porous material such as alumina is embedded in the upper surface of the chuck spindle 31. The chuck table 3 includes a pipeline (not shown) that passes through the inside and extends to the surface. The pipeline is connected to a vacuum source, a compressed air source, or a water supply source via a rotary joint (not shown). When the vacuum source is activated, the workpiece W placed on the chuck table 3 is adsorbed and held by the adsorbent 32. When the compressed air source or the water supply source is activated, the adsorption between the workpiece W and the adsorbent 32 is released.

[0023] The chuck table 3 may be provided with a tilt mechanism (not shown) that inclines the rotation axis 3a relative to the rotation axis 2a of the grinding wheel 24. This allows the contact between the grinding wheel 24 and the workpiece W to be adjusted, enabling the workpiece W to be ground into a desired shape.

[0024] The operation of the grinding device 1 is controlled by a control unit (not shown). The control unit controls each of the components that make up the grinding device 1. The control unit is composed of, for example, a CPU, memory, etc. The functions of the control unit may be realized by control using software or by operation using hardware.

[0025] Next, we will explain the procedure for grinding the workpiece W using the grinding device 1.

[0026] First, the workpiece W is held in place by suction on the chuck table 3. Next, the grinding wheel 21 is moved above the workpiece W by the spindle feed mechanism 23. Then, as shown in Figure 3, the grinding wheel 21 and the chuck table 3 are rotated respectively, and the grinding wheel 24 is pressed against the workpiece W, thereby grinding the workpiece W in an infeed manner.

[0027] Then, as shown in Figure 4, the frictional heat generated when the grinding wheel 24 cuts into the workpiece W causes carbon atoms smaller than ferrite in the workpiece W to enter the crystal structure of the pure iron (ferrite) used in the grinding aid 27, maintaining the crystal structure of the iron atoms, and the iron atoms and carbon atoms mix in a solid state (carbon solid solution phenomenon). Then, as shown in Figure 5, the contact between the diamond abrasive grains 26 of the grinding wheel 21 and the carbon atoms of the workpiece W is reduced by the amount of carbon atoms C that have escaped from the workpiece W.

[0028] When the workpiece W is ground to the desired thickness, the rotation of the grinding wheel 21 and the chuck table 3 is stopped, and the slider of the spindle feed mechanism 23 is activated to move the grinding wheel 21 away from the workpiece W. Then, the suction holding of the workpiece W by the chuck table 3 is released, and the grinding process of the workpiece W by the grinding device 1 is completed.

[0029] Thus, the grinding wheel 21 according to this embodiment is a grinding wheel 21 for grinding a workpiece W which is a diamond wafer, and is configured to include a grinding wheel 24 that contains at least diamond abrasive grains 26, a grinding aid 27 made of pure iron, and a bonding agent 28.

[0030] With this configuration, the carbon atoms of the workpiece W are dissolved into the iron atoms of the grinding aid 27 by the frictional heat generated during grinding. As a result, the workpiece W becomes more brittle due to the loss of carbon atoms, which suppresses the wear of the diamond abrasive grains 26 and allows the grinding wheel 24 to grind the workpiece W efficiently.

[0031] Furthermore, the present invention can be modified in various ways other than those described above, as long as it does not deviate from the spirit of the invention, and it goes without saying that the present invention extends to such modified forms. [Explanation of Symbols]

[0032] 1: Grinding device 2: Grinding means 21: Grinding Wheel 21a: Grinding surface 22: Grinding wheel spindle 23: Spindle feed mechanism 24: Sharpening stone 25: Base 26: Diamond abrasive grains 27: Grinding aids 28: Bonding agent 29: Column 3: Chuck Table 3a: Rotation axis 31: Chuck Spindle W: Work

Claims

1. A grinding apparatus equipped with a grinding wheel for grinding diamond wafers, The grinding wheel comprises a grinding stone containing at least abrasive grains, a grinding aid made of pure iron, and a bonding agent. A grinding apparatus characterized by comprising a control unit that controls the grinding wheel to incorporate carbon atoms contained in the diamond wafer into the pure iron contained in the grinding wheel when the grinding wheel grinds the diamond wafer, due to the frictional heat generated when the grinding wheel cuts into the diamond wafer.

2. A grinding method for grinding a diamond wafer using a grinding wheel, The grinding wheel comprises a grinding stone containing at least abrasive grains, a grinding aid made of pure iron, and a bonding agent. A grinding method characterized in that, when the grinding wheel grinds the diamond wafer, the frictional heat generated when the grinding wheel cuts into the diamond wafer causes carbon atoms contained in the diamond wafer to be incorporated into the pure iron contained in the grinding wheel.

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