JP2023139462A - Grinding wheel and grinding device - Google Patents

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

The present invention relates to a grinding wheel and a grinding device used when grinding a diamond wafer.

In the field of semiconductor manufacturing, a grinding device is known that grinds a semiconductor wafer into a thin, flat surface by pressing a grindstone of a rotating grinding wheel against the semiconductor wafer.

Patent Document 1 discloses a cup-shaped grinding wheel including a resin bonded grinding wheel using diamond abrasive grains.

Japanese Patent Application Publication No. 2005-205543

However, when grinding a semiconductor wafer made of diamond (hereinafter referred to as a "diamond wafer") with a grindstone made of diamond abrasive grains, the diamonds come into contact with each other, which causes the grindstone to wear easily and the equipment cost to be high. there were.

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

In order to achieve the above object, a grinding wheel according to the present invention is a grinding wheel for grinding a diamond wafer, and includes a grinding wheel containing at least abrasive grains, a grinding aid made of pure iron, and a bonding agent. ing.

Moreover, in order to achieve the said objective, the grinding apparatus based on this invention is equipped with the grinding wheel of Claim 1.

According to the present invention, a grinding wheel for grinding diamond wafers can be used for a long period of time.

FIG. 1 is a front view showing a grinding device according to an embodiment of the present invention. FIG. 2 is a perspective view showing the structure of a grinding wheel. A schematic diagram and a partially enlarged diagram showing a state in which a workpiece is being ground. A schematic diagram showing a state in which carbon atoms of a workpiece are dissolved in iron atoms of a grindstone. A schematic diagram showing a state in which a workpiece whose surface has become brittle is being ground.

An embodiment of the present invention will be described based on the drawings. In addition, in the following, when referring to the number, numerical value, amount, range, etc. of constituent elements, the term is limited to that specific number, unless it is specifically specified or it is clearly limited to a specific number in principle. It doesn't matter if it's more than or less than a certain number.

In addition, when referring to the shape or positional relationship of constituent elements, etc., unless it is specifically specified or it is clearly considered that it is not the case in principle, etc., we refer to things that are substantially similar to or similar to the shape, etc. include.

Further, in the drawings, characteristic parts may be enlarged or exaggerated in order to make the features easier to understand, and the dimensional ratios of the constituent elements are not necessarily the same as in reality. Further, in the cross-sectional views, hatching of some components may be omitted in order to make the cross-sectional structure of the components easier to understand.

A grinding device 1 shown in FIG. 1 grinds a workpiece W into a thin and flat workpiece. The workpiece W is a diamond wafer made of diamond. The grinding device 1 includes a grinding means 2 and a chuck table 3.

The grinding means 2 includes a grinding wheel 21, a grindstone spindle 22, and a spindle feeding mechanism 23.

The lower surface of the grinding wheel 21 constitutes a grinding surface 21a for grinding the workpiece W. The grinding wheel 21 is a cup-shaped grindstone and is attached to the lower end of the grindstone spindle 22. The grindstone spindle 22 is configured to rotate the grinding wheel 21 around the rotation axis 2a.

The spindle feeding mechanism 23 moves the grindstone spindle 22 up and down. The spindle feeding mechanism 23 has a known configuration, and includes, for example, a plurality of linear guides that guide the movement direction of the grindstone spindle 22 and a ball screw slider mechanism that moves the grindstone spindle 22 up and down. The spindle feeding mechanism 23 is interposed between the grindstone spindle 22 and the column 29.

As shown in FIG. 2, the grinding wheel 21 includes a plurality of grindstones 24 formed in a segment shape, and at least a portion of these grindstones 24 are buried in an annular groove (not shown) so that the grindstones 24 are arranged at predetermined intervals. A base 25 for holding. The base 25 is fastened to the grindstone spindle 22 via bolts (not shown).

The grindstone 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 aid 27 has a metal structure of alpha iron (ferrite) in the temperature range during processing when the grindstone 24 cuts into the workpiece W, and exhibits a fine body-centered cubic lattice structure.

The whetstone 24 is made by kneading diamond abrasive grains 26 and a grinding aid 27 at a predetermined ratio, molding the mixture into a predetermined shape, and sintering the molded product with a bonding agent 28 . The mixing ratio of the diamond abrasive grains 26 and the grinding aid 27 is set to 50% by weight, for example. Note that 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 depending on the type of workpiece W and processing conditions. Note that 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.

The chuck table 3 includes a chuck spindle 31. The chuck spindle 31 is configured to be driven to rotate around the rotating shaft 3a.

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 is equipped with a conduit (not shown) extending through the inside and extending to the surface. The pipe line is connected to a vacuum source, compressed air source, or 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 held by the suction body 32. Further, when the compressed air source or the water supply source is activated, the adsorption between the workpiece W and the adsorbent 32 is released.

The chuck table 3 may be provided with a tilt mechanism (not shown) that tilts the rotation axis 3a with respect to the rotation axis 2a of the grindstone 24. Thereby, the contact between the grindstone 24 and the workpiece W can be adjusted to grind the workpiece W into a desired shape.

The operation of the grinding device 1 is controlled by a control section (not shown). The control unit controls each of the constituent elements constituting the grinding device 1. The control unit includes, for example, a CPU, a memory, and the like. Note that the functions of the control unit may be realized by controlling using software, or may be realized by operating using hardware.

Next, a procedure for grinding the workpiece W with the grinding device 1 will be explained.

First, the workpiece W is suctioned and held on the chuck table 3. Next, the grinding wheel 21 is moved above the work W by the spindle feed mechanism 23. Then, as shown in FIG. 3, the grinding wheel 24 is pressed against the workpiece W while rotating the grinding wheel 21 and the chuck table 3, thereby grinding the workpiece W in an infeed manner.

As shown in FIG. 4, the frictional heat generated when the grinding wheel 24 cuts into the workpiece W causes the carbon atoms smaller than the ferrite in the workpiece W to melt into the crystal structure of pure iron (ferrite) used for the grinding aid 27. The crystal structure of iron atoms is maintained, and iron atoms and carbon atoms mix in a solid state (carbon solid solution phenomenon). Then, as shown in FIG. 5, the contact between the diamond abrasive grains 26 of the grindstone 21 and the carbon atoms of the work W is reduced by the amount that the carbon atoms C of the work W escape.

When the workpiece W is ground to a 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 separate the grinding wheel 21 from the workpiece W. Then, the suction and holding of the work W by the chuck table 3 is released, and the grinding of the work W by the grinding device 1 is completed.

In this way, the grinding wheel 21 according to the present embodiment is a grinding wheel 21 for grinding a workpiece W, which is a diamond wafer, and includes diamond abrasive grains 26, a grinding aid 27 made of pure iron, and a bonding agent 28. The grindstone 24 includes at least the following.

With such a configuration, the carbon atoms of the workpiece W are dissolved into the iron atoms of the grinding aid 27 due to frictional heat during grinding, and the workpiece W becomes brittle by the amount of carbon atoms that have escaped. , wear of the diamond abrasive grains 26 is suppressed, and the grindstone 24 can efficiently grind the workpiece W.

Further, the present invention can be modified in various ways other than those described above without departing from the spirit of the invention, and it goes without saying that the present invention extends to such modifications.

1: Grinding device 2: Grinding means 21: Grinding wheel 21a: Grinding surface 22: Grinding wheel spindle 23: Spindle feeding mechanism 24: Grinding wheel 25: Base 26: Diamond abrasive grains 27: Grinding aid 28: Bonding agent 29: Column 3: Chuck table 3a: Rotating shaft 31: Chuck spindle W: Workpiece

Claims (2)

A grinding wheel for grinding a diamond wafer,
A grinding wheel comprising a grinding wheel containing at least abrasive grains, a grinding aid made of pure iron, and a bonding agent. A grinding device comprising the grinding wheel according to claim 1.

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