TWI707027B - Grinding grindstone - Google Patents

Abstract

The present invention provides a grinding stone capable of achieving at least one of reduction in processing load and increase in life.

The present invention provides grinding grindstones 34, 37 that contain diamond abrasive grains and boron compounds, and are used to grind processed objects; the average particle size X of diamond abrasive grains is 3μm≦X≦10μm, the pair of boron compounds The average particle diameter ratio Z of diamond abrasive grains is 0.8≦Z≦3.0. Suitably, the workpiece is a SiC wafer, and the average particle size ratio Z is 1.2≦Z≦2.0.

Description

Grinding grindstone Invention field

The present invention is related to a grinding stone for grinding a workpiece.

Background of the invention

In order to grind the substrate used in semiconductor manufacturing, a grinding grindstone added with a boron compound is used (see, for example, Patent Document 1). Because the boron compound has solid lubricity, it has an inhibitory effect on the heat generation at the processing point formed by the grinding process and the consumption of the grindstone.

【Prior Technical Literature】 【Patent Literature】

[Patent Document 1] JP 2012-056013 No.

Summary of the invention

However, in the grinding grindstone shown in Patent Document 1, when a hard substrate (for example, a SiC substrate) is ground, the processing load applied to the grindstone increases, so the consumption of the grindstone also increases and the frequency of replacement Becomes high. In addition, when grinding glass and other materials with poor thermal conductivity, in order to suppress the heat generated by processing The processing speed cannot be increased. Therefore, the grinding grindstone is required to not only maintain the processing characteristics of the workpiece, but also to improve the productivity.

The present invention has been accomplished in view of the above-mentioned problems, and its object is to provide a grinding stone capable of achieving at least one of reduction in processing load and long life.

According to the present invention, the provided grinding grindstone is a grinding grindstone for grinding a workpiece, and it is characterized in that the grinding grindstone contains diamond abrasive grains and a boron compound in a predetermined volume ratio, and the diamond abrasive grains The average particle size X is 3 μm≦X≦10 μm, and the average particle diameter ratio Z of the boron compound to the diamond abrasive grain is 0.8≦Z≦3.0.

It is suitable that the processing object of the grinding grindstone, that is, the workpiece is a SiC wafer, and the aforementioned average particle size ratio Z is preferably 1.2≦Z≦2.0.

The grinding stone invented in this case, by controlling the particle size (particle size ratio) of the boron compound relative to the particle size of the diamond abrasive particles, on the one hand, it can improve the processing quality, and at the same time, it can achieve the goal of grinding stone. Reduction of processing load, improvement of heat dissipation, and long life (reduction of consumption).

10: Grinding device

11: The first storage box

12: The second storage box

13: Move in and out of the organization

15,16: Transport mechanism

17~19: Suction cup table

20: Rotating table

30, 40: Grinding mechanism

37: Grinding stone for rough grinding

47: Grinding stone for fine grinding

W: Wafer (worked object)

[Fig. 1] Fig. 1 is a schematic diagram of a configuration example of a grinding device equipped with a grinding grindstone in an embodiment.

[Figure 2] Figure 2 is a graph showing the consumption rate (%) of the average particle size of the boron compound of the grinding grindstone for rough grinding.

[Figure 3] Figure 3 is a comparison of the boron compound of the grinding stone for rough grinding Schematic diagram of the maximum grinding load (N) of the average particle size.

Detailed description of the preferred embodiment

The implementation aspects of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the content described in the following embodiments. In addition, the constituent elements described below include solutions that can be easily inferred by those skilled in the art, and substantially the same solutions. In addition, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

[Implementation status]

Fig. 1 is a schematic diagram of a configuration example of a grinding device equipped with a grinding grindstone in an embodiment. In addition, the X-axis direction in the same figure is the width direction of the grinding device 10, the Y-axis direction is the depth direction of the grinding device 10, and the Z-axis direction is the vertical direction.

As shown in FIG. 1, the grinding device 10 includes: a first storage box 11 and a second storage box 12 for storing a plurality of wafers W as workpieces, and a second storage box 12 that also serves as the first storage box 11 The common carry-out mechanism 13 for carrying out the wafer W and the carrying-in mechanism for carrying the ground wafer W into the second storage box 12, the calibration mechanism 14 that performs the alignment of the center position of the wafer W, and the wafer transfer mechanism. Round W transport mechanism 15, 16, three suction table 17-19 that suck and hold wafer W, turntable 20 that supports and rotates these several suction table 17-19 rotatably, pair is held in The wafer W of each suction table 17-19 is implemented as a grinding mechanism for the grinding process of processing 30, 40. A cleaning mechanism 51 for cleaning the wafer W after grinding, and a cleaning mechanism 52 for cleaning the suction table 17-19 after grinding.

In the above-mentioned grinding apparatus 10, the wafer W contained in the first magazine 11 is transported to the alignment mechanism 14 by the unloading action of the unloading and in-feeding mechanism 13, and after centering is performed here, the wafer W is transported and placed by the transport mechanism 15 On the suction table 17-19, in the same figure, it is conveyed and placed on the suction table 17. The three sucker tables 17-19 in this embodiment are arranged at equal intervals in the circumferential direction with respect to the turntable 20, and are assembled so that each can rotate, and at the same time will move on the XY plane as the turntable 20 rotates. structure. The chuck tables 17 to 19 are rotated by a predetermined angle, for example, 120 degrees counterclockwise while sucking and holding the wafer W, and are positioned directly below the grinding mechanism 30.

The grinding mechanism 30 is configured to perform rough grinding of the wafers W held on the chuck tables 17 to 19, and is provided on the wall 22 standing upright at the end of the base 21 in the Y-axis direction. The grinding mechanism 30 is assembled so that it is guided by a pair of guide rails 31 arranged on the wall 22 along the Z-axis direction, and is supported by a support part 33 driven by a motor 32 for vertical movement, and accompanied by support The vertical movement of the portion 33 performs vertical movement in the Z-axis direction. The grinding mechanism 30 includes a motor 34 that rotates the rotatably supported spindle 34a, and a grinding wheel that is mounted on the front end of the spindle 34a through a wheel mount 35 to grind the back of the wafer W 36. The grinding wheel 36 has a grinding grindstone 37 for rough grinding fixed in an annular shape on the lower surface thereof. In addition, rough grinding refers to grinding to thin the wafer W to a desired thickness.

The embodiment of rough grinding is that the spindle 34a is driven by the motor 34 and As a result, the grinding wheel 36 rotates and is ground and fed below the Z axis, so that the rotating grinding stone 37 comes into contact with the back of the wafer W, and the grinding wheel 36 is held on the suction table 17 and positioned Grinding is performed on the back surface of the wafer W directly below the grinding mechanism 30. Here, if the rough grinding of the wafer W held on the chuck table 17 is finished, the turntable 20 will only rotate a predetermined angle in the counterclockwise direction, thereby positioning the rough ground wafer W to the grinding mechanism Just below 40.

The grinding mechanism 40 is configured to perform finish grinding of the wafers W held on the chuck tables 17-19, and is assembled so as to be guided by a pair of guide rails 41 arranged on the wall 22 along the Z-axis direction. It is supported by the support part 43 which is driven by the motor 42 for vertical movement, and with the vertical movement of the support part 43, it moves vertically in the Z-axis direction. The grinding mechanism 40 includes a motor 44 that rotates the rotatably supported spindle 44a, and a grinding wheel that is mounted on the front end of the spindle 44a through a wheel mount 45 to grind the back of the wafer W 46. The grinding wheel 46 has a grinding grindstone 47 for fine grinding fixed in a ring shape on its bottom surface. That is, the basic configuration of the grinding mechanism 40 and the grinding mechanism 30 are the same, and only the types of the grinding grindstones 37 and 47 have different configurations. In addition, the finish grinding refers to grinding that thins the wafer W to a predetermined thickness while removing the grinding marks generated on the back surface of the wafer W due to rough grinding.

The implementation of fine grinding is that the spindle 44a is driven by the motor 44 to rotate, and the grinding wheel 46 rotates accordingly, and is ground and fed below the Z axis, so that the rotating grinding stone 47 contacts The backside of the wafer W is further opposed to the wafer held on the chuck table 17 and positioned directly below the grinding mechanism 40 The back of circle W is ground. Here, if the finish grinding of the wafer W held on the chuck table 17 is completed, the turntable 20 will only rotate a predetermined angle in the counterclockwise direction, thereby returning to the initial position shown in FIG. 1. In this position, the wafer W whose back surface has been finely ground is transported by the transport mechanism 16 to the cleaning mechanism 51, and after the grinding debris is removed by cleaning, it is then transported into the first by the carry-in action of the carry-out mechanism 13 Two storage box 12. In addition, the cleaning mechanism 52 cleans the chuck table 17 in which the polished wafer W is picked up by the transport mechanism 16 and placed in an idle state. Furthermore, the rough grinding and finishing grinding of the wafer W held on the other chuck tables 18 and 19, the loading and unloading of the wafer W on the other chuck tables 18 and 19, etc., The same applies to the rotation position of the turntable 20.

It is appropriate that the wafer W to be ground by the grinding stone of this embodiment is a SiC wafer containing SiC (silicon carbide). SiC wafers are harder materials than wafers made of silicon.

Here, the grinding stones 37, 47 used for rough grinding or fine grinding of the SiC wafer, that is, the wafer W, are formed by bonding diamond abrasive grains and a boron compound with an adhesive. Diamond abrasive grains refer to at least one of natural diamonds, synthetic diamonds, and metal-coated synthetic diamonds. The boron compound refers to at least one of B ₄ C (boron carbide), CBN (cubic boron nitride), and HBN (hexagonal boron nitride). Grinding stones 37 and 47 are made of any one of ceramic bond, resin bond and metal bond used as a bonding agent. Diamond abrasive grains and boron compound are mixed and sintered, or they are fixed by nickel plating. of. The volume ratio of diamond abrasive particles and boron compound should be 1:1~1:3.

When the average particle size of the boron compound is Y [μm] and the average particle size of the diamond abrasive grains is X [μm], in the grinding grindstone 37, the ratio of the average particle size of the boron compound to the diamond abrasive grains is Z (= Y/X) is 0.8≦Z≦3.0. Here, the average particle size ratio Z is set to 0.8 or more because, if it is less than 0.8, the function and effect of the boron compound as a structural material (filler) that makes the grinding grindstone 37 brittle will increase. On the other hand, the average particle size ratio Z is set to 3.0 or less because, if it exceeds 3.0, diamond abrasive grains, which are the main abrasive grains, have a greater function as a structural material than they function as abrasive grains. Contribute to the grinding process. In addition, the average particle diameter X of diamond abrasive grains is 3 μm≦X≦10 μm. Here, the average particle diameter X of the diamond abrasive grains is set to 10 μm or less because the average particle diameter X is used for the grinding process of the wafer W, which is a harder SiC wafer than the silicon wafer on which electronic devices are formed. Diamond abrasive grains below 10 μm are suitable.

In this embodiment, in the grinding stone 37 used for rough grinding of the wafer W of the SiC wafer, the average particle size X of the diamond abrasive grains is preferably 3 μm≦X≦10 μm. Because in the grinding stone 37 for rough grinding, if diamond abrasive grains with an average particle size X of less than 3μm are used, not only the time required for rough grinding will increase, but the grinding stone 37 will become brittle. . In the grinding grindstone 47 used for fine grinding of wafer W of SiC wafer, the average particle size X of diamond abrasive grains should be used as a grinding grindstone for fine grinding than for rough grinding. The average particle size of the grindstone is small, for example, 0.5 μm≦X≦1 μm.

As described above, the average particle size ratio Z of the boron compound to the diamond abrasive grains is set to 0.8≦Z≦3.0, and the average particle size X of the diamond abrasive grains is set to 3μm≦X≦10μm, whereby the wafer W is being ground Solid lubrication of boron compound The sexual characteristics will effectively work to reduce the processing load of the grinding stone 37. Therefore, since the processing load of the grinding stone 37 is reduced, when one wafer W is ground by the grinding stone 37, the consumption of the grinding stone 37 can be reduced, and as a result, the life can be increased. In addition, it is possible to suppress the heat generation of the workpiece at the processing point during the grinding process caused by the grinding of the grindstone 37, to increase the grinding speed, and to improve the productivity. From the above, in the grinding device 10, the consumption of the grinding stone 37 is also reduced, the frequency of replacement of the grinding stone can be reduced, and the overall productivity of the grinding process of the grinding device 10 can be improved. Since the average particle size ratio Z of the grinding grindstone 37 is 0.8≦Z≦3.0, it is possible to achieve at least one of a reduction in processing load and a longer life.

In addition, in this embodiment, the grinding stone 37 used for rough grinding of the wafer W of the SiC wafer preferably has an average particle size ratio Z of 1.2≦Z≦3.0. In this case, the grinding stone 37 can suppress consumption during grinding, and can achieve a long life.

Furthermore, in this embodiment, the grinding stone 37 used for rough grinding of the wafer W of the SiC wafer preferably has an average particle size ratio Z of 0.8≦Z≦2.0. In this case, the grinding stone 37 can reduce the processing load.

In addition, in this embodiment, the grinding stone 37 used for rough grinding of the wafer W of the SiC wafer has an average particle size of 1.2≦Z≦2.0 that is more preferable than Z. In this case, both the reduction of the machining load and the longer life can be achieved by the grinding grindstone 37.

Example

Next, in order to confirm the effects of the present invention, the inventors of the present invention produced grinding stones 37 for rough grinding with different average particle diameters of boron compounds. The consumption rate and the maximum grinding load of the grinding stone 37 when the wafer W of the SiC wafer is subjected to rough grinding is measured. The results are shown in Figure 2 and Figure 3. Fig. 2 is a graph showing the consumption rate (%) of the average particle size of the boron compound relative to the grinding grindstone for rough grinding; Fig. 3 is the average particle size of the boron compound relative to the grinding grindstone for rough grinding Schematic diagram of the maximum grinding load (N).

The grinding grindstone 37 for rough grinding used in FIGS. 2 and 3 is formed by kneading and sintering a binder whose main component is SiO ₂ and diamond abrasive grains using CBN as a boron compound. The rough grinding grinding stone 37 used in FIGS. 2 and 3 has an average particle diameter X of diamond abrasive grains of 4 μm, a volume ratio of boron compound to diamond abrasive grains of 1:1, and a The average particle size Y varies from 3μm to 20μm.

The horizontal axis in FIGS. 2 and 3 represents the average particle diameter Y and the average particle diameter ratio Z of the boron compound. The vertical axis in FIG. 2 represents the consumption rate of the grinding stone 37. This consumption rate is the consumption (%) of the grinding stone 37 relative to the actual grinding amount. The vertical axis in Figure 3 is the maximum value (N) of the load borne during rough grinding. In addition, in FIGS. 2 and 3, a plurality of grinding stones 37 for rough grinding with an average particle diameter Y of a boron compound having the same average particle diameter Y are produced, and then the measurement is made with each pair of grinding stones 37 as the The consumption rate and maximum grinding load of the processed SiC wafer during rough grinding. In addition, in FIG. 2 and FIG. 3, the average value of the consumption rate and the maximum grinding load is shown by a broken line.

It can be seen from Fig. 2 that the average particle size ratio Z is set to 1.2 or more and 3.0 or less. Compared with the average particle size ratio Z being set to a value less than 1.2 or more than 3.0, the consumption rate of the grinding stone 37 can be suppressed to 10 Below about %. In addition, according to Fig. 3, it can be seen that the average particle size ratio Z is set to 0.8 or more and 2.0 or less. When the average particle diameter ratio Z is set to a value exceeding 2.0, the maximum grinding load (that is, the reduction in the machining load) can be more suppressed. In addition, it can be seen from FIG. 2 that if the average particle diameter ratio Z is set to less than 0.8, the consumption rate of the grinding grindstone 37 will increase.

In this way, according to Figures 2 and 3, it can be seen that the grinding grindstone 37 can achieve at least one of a long life and a reduction in processing load by setting the average particle size ratio Z to 0.8 or more and 3.0 or less; If the average particle diameter ratio Z is set to 1.2 or more and 2.0 or less, both longevity and reduction in processing load can be achieved.

In addition, in the foregoing embodiments and examples, although the grinding stone 37 is mainly described, the present invention can also be applied to the grinding stone 47 for finish grinding.

10‧‧‧Grinding device

11‧‧‧The first storage box

12‧‧‧Second storage box

13‧‧‧Move in and out of organization

15,16‧‧‧Transportation mechanism

17~19‧‧‧Suction cup table

20‧‧‧Rotating table

30,40‧‧‧Grinding mechanism

37‧‧‧Grinding stone for rough grinding

47‧‧‧Grinding stone for fine grinding

W‧‧‧wafer (processed object)

Claims (4)

A grinding grindstone for grinding a workpiece. The aforementioned grinding grindstone is characterized in that the grinding grindstone contains diamond abrasive grains and a boron compound in a predetermined volume ratio, and the average particle size of the diamond abrasive grains X is 3 μm≦X≦10 μm, and the average particle diameter ratio Z of the boron compound to the diamond abrasive grain is 1.2≦Z<2.0. Such as the grinding stone of claim 1, wherein the aforementioned workpiece is a SiC wafer. Such as the grinding stone of claim 1, wherein the predetermined volume ratio of the diamond abrasive grains and the boron compound is 1:1 to 1:3. The grinding stone of claim 1, wherein the boron compound is selected from the group consisting of boron carbide, cubic boron nitride (CBN) and hexagonal boron nitride (HBN).

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