JP5708147B2 - Grinding wheel, double-head grinding method and silicon wafer manufacturing method - Google Patents

Description

The present invention, grinding WHEEL, a method of manufacturing a double-disc grinding method and the silicon wafer.

  Conventionally, a cup-type wheel is used as a grinding wheel for grinding an object to be ground. Generally, a cup-type grinding wheel has an annular grindstone provided on a wheel base. The grindstone includes a plurality of chips provided at predetermined intervals along the annular outer circumferential direction.

As a grinding wheel as described above, a configuration as described in Patent Document 1 is known.
This Patent Document 1 discloses a grinding wheel for grinding ceramics and stone materials. The average particle diameter is 100 μm in the slits between the chips of this grinding wheel (side regions defined by the sides facing each other, the lines connecting the base ends of the adjacent chips, and the lines connecting the tips). A single layer of superabrasive grains of ˜2000 μm are fixed.

As a grinding method using a cup-type grinding wheel, a method of grinding a wafer as described in Patent Document 2 is known.
This Patent Document 2 discloses a method of supplying a grinding liquid from a central hole of a grinding wheel and cooling the central portion of a wafer with a cooling liquid.

JP-A-11-291174 Japanese Patent No. 3776624

  By the way, Patent Documents 1 and 2 disclose grinding wheels in which the chip interval dimension (adjacent chip interval dimension) is set constant in the chip height direction (chip protruding direction). However, using such a grinding wheel, a plurality of wafers are sequentially placed under a constant grinding condition such as the amount of grinding fluid supplied into the grinding wheel, the grinding time per wafer, and the rotational speed of the grinding wheel. When grinding, there is a problem that as the chip wears, the ground wafer warps and the flatness deteriorates.

An object of the present invention, even when the wear of the chip is developed to provide quality sustainable grinding WHEEL of object to be ground, a manufacturing method of double-disc grinding method and the silicon wafer.

  The present inventor conducted experiments using a grinding wheel 9 as shown in FIG. 2 in a double-head grinding apparatus 1 as shown in FIG. 1 and conducted extensive research, and as a result, found the following knowledge.

  Here, the double-head grinding apparatus 1 includes a carrier ring 2 that holds a wafer W as an object to be ground inside, and grinding wheels that are respectively disposed so as to face both surfaces of the wafer W held by the carrier ring 2. 9 and a grinding mechanism (not shown) that drives the grinding wheel 9 to grind the wafer W.

The grinding wheel 9 includes a wheel base 91 that is, for example, a diamond wheel, and a grindstone 92 that protrudes from one surface of the wheel base 91.
The wheel base 91 includes a disk-shaped disk portion 911 and a convex portion 912 that protrudes in an annular shape from the outer edge of the disk portion 911. In the center of the disc portion 911, a grinding fluid supply hole 913 that penetrates both surfaces of the disc portion 911 is provided. The grinding liquid is supplied into the grinding wheel 9 (in the grindstone 92) through the grinding liquid supply hole 913.
The grindstone 92 is formed by bonding abrasive grains with vitrified bonds. The grindstone 92 includes an annular grindstone base 921 and a plurality of chips 922 provided along the outer circumferential direction of the grindstone base 921. As shown in FIG. 2, the chip 922 is formed in a rectangular plate shape having a height dimension H91 (a dimension from the base end to the tip end of the chip 922) of 12 mm and a thickness dimension of 3 mm. Further, the chip interval dimension D91 between adjacent chips 922 is set to 1 mm. With such a configuration, an inter-chip slit S9 having a width dimension equal to the chip interval dimension D91 regardless of the height position is formed between the grindstone base 921 and the adjacent chips 922.

  As shown in FIG. 1, the grinding mechanism rotates the grinding wheel 9 on both sides of the wafer W set up in the vertical direction, and presses the grindstone 92 to a position below the center of the wafer W. Simultaneously with this pressing, the wafer W is ground by supplying the grinding liquid into the grinding wheel 9 and rotating the wafer W.

In conducting the experiment, three types of grinding wheels 9 were prepared in which the height dimension H91 of the tip 922 was set to 3.5 mm, 9 mm, and 12 mm, respectively. Then, a predetermined amount of grinding fluid was supplied into the grinding wheel 9 to grind the five wafers W.
At this time, grinding was performed with the supply flow rate of the grinding fluid set to the 4th or 5th level. In addition, the grinding conditions other than the grinding fluid supply flow rate (grinding time per wafer, rotational speed of the grinding wheel 9, etc.) were the same for all grindings.
Then, the relationship between the supply flow rate (L / min) of the grinding fluid and the quality of the wafer W at each height dimension H91 was examined. The result is shown in FIG.

The quality of the wafer W was evaluated based on Bow-bf. When Bow-bf is 0 μm, the measurement surface (ground surface) of the wafer W is flat and represents a good quality state.
Here, Bow is one of the indices expressing the warpage of the entire wafer, and is expressed by the displacement from the center reference plane of the wafer to the center plane at the midpoint of the wafer. The surface is created by a three-point (Bow-3P) or best-fit (Bow-bf) criterion on the center surface. Therefore, in the Bow value, a value represented by plus (+) has a convex warp, and a value represented by minus (−) has a concave warp. For example, the amount of warpage can be measured using an optical sensor type flatness measuring device (Wafercom, manufactured by Lapmaster SFT).

As shown in FIG. 3, an approximate curve of average Bow−bf (average value of Bow−bf of five wafers W) was obtained for the grinding wheel 9 having each height dimension H91.
From this approximate curve, it can be estimated that the supply flow rate of the grinding fluid that improves the quality of the wafer W (average Bow-bf is 0 μm) varies depending on the height dimension H91. This result is consistent with the conventional problem that the amount of warpage of the wafer W increases as the chip 922 wears when grinding is performed with all the grinding conditions including the supply flow rate made constant.

From the results shown in FIG. 3, even when the wear of the chip 922 progresses, as a measure for stabilizing the quality of the wafer W, it is considered to adjust the flow rate of the grinding fluid supplied to the grinding wheel 9 by the height dimension H91. It is done. However, in order to adjust the supply flow rate of the grinding fluid, it is necessary to introduce new equipment, which causes a new problem that the configuration and control of the double-head grinding apparatus 1 are complicated.
Therefore, the present inventor has examined a method capable of stabilizing the quality without adjusting the supply flow rate of the grinding fluid, and the slit area (the area of the slit between the chips) as the chip height dimension decreases. We paid attention to the fact that becomes smaller.

  When the supply flow rate of the grinding fluid into the grinding wheel 9 is constant, the smaller the slit area, the faster the estimated outflow velocity of the grinding fluid (the estimated flow velocity of the grinding fluid flowing out from the inter-chip slit S9) (mm / sec). . Therefore, for each height dimension H91, the quality of the wafer W is stabilized and improved from the supply flow rate estimated to have Bow-bf of 0 μm and the total slit area of the grinding wheel 9 as a whole. The estimated outflow velocity was calculated (such that Bow-bf was approximately 0 μm). An approximate curve of the estimated outflow velocity is shown as a target level in FIG.

If the estimated outflow velocity at each height dimension H91 changes to the value indicated by the target level in FIG. 4, the quality of the wafer W is considered to be stable and improved.
However, when the estimated outflow velocity at each height dimension H91 was calculated when the grinding fluid supply flow rate was kept constant at 1.6 L / min, an approximate curve as shown in FIG. 4 as an experimental example was obtained.
From this result, when the height dimension H91 is 7 mm or more and 12 mm or less, the estimated outflow velocity changes at a value close to the target level, while the estimated outflow velocity moves away from the target level as it becomes smaller than 7 mm. Can be estimated.
From the above, even when the wear of the tip 922 progresses and the height dimension H91 becomes small, if the size of the slit area changes so that the estimated outflow velocity changes at a value close to the target level, It can be estimated that the quality of the wafer W is stable and improved without adjusting the supply flow rate of the grinding fluid.
The present invention has been completed based on such findings.

  That is, the grinding wheel of the present invention is a grinding wheel used for grinding an object to be ground using a grinding fluid, and is provided so as to project from a substantially plate-like wheel base and one surface of the wheel base in an annular shape. A grindstone pressed against the workpiece, and the grindstone has a plurality of chips provided along the annular outer circumferential direction, and the interval between adjacent chips is determined from the tip side of the chip. Also, the base end side is set to be larger.

According to the present invention, the tip interval dimension on the proximal end side of the grinding wheel is made larger than the tip interval dimension on the distal end side.
For this reason, compared with the conventional structure which set the chip | tip space | interval dimension uniformly irrespective of the height position of a chip | tip, the slit area in the stage where the chip | tip was worn to the base end side can be enlarged. Therefore, even when the supply flow rate of the grinding fluid is constant, the estimated outflow velocity when the wear of the tip progresses to the proximal end side becomes slower than the conventional one, and the estimated outflow velocity can approach the target level. . Therefore, even when all the grinding conditions are made constant and a plurality of objects to be ground are sequentially ground, the warpage of the object to be ground due to chip wear can be suppressed, and the quality can be stabilized.

In the grinding wheel of the present invention, the height dimension of the chip (the dimension from the base end to the tip end of the chip) is H (mm), the inter-chip slits (the opposite sides of adjacent chips, the base end of the adjacent chip) A (H) (mm ² ), the total flow area that is defined by the line connecting each other and the line connecting the tips, and the supply flow rate of the grinding fluid supplied to the grinding wheel when grinding the workpiece , C (mm ³ / sec), the flow rate of the grinding fluid flowing out from the slit between the chips is F (H) (mm / sec), and the supply flow rate C of the grinding fluid is constant, the adjacent fluids are adjacent to each other. The distance between the chips is a flow rate F (H) that increases due to a change in the height dimension H of the tip that is worn by the grinding process, and a flow rate F ( H) The total area of the slits between the chips necessary for the reduction to It is preferably set to be A (H).

  According to the present invention, the quality of the workpiece can be stabilized by setting the interval between adjacent chips as described above.

In the grinding wheel of the present invention, the distance between adjacent chips is such that the height of the chip (the dimension from the base end to the tip of the chip) is H (mm), and the height of the chip is H (mm). In this case, the sum of the areas of the inter-chip slits (regions defined by opposing sides of adjacent chips, a line connecting the base ends of the adjacent chips, and a line connecting the tips) is represented by A (H ) (Mm ² ), when the grinding fluid supply flow rate is C (mm ³ / sec) and the tip height is H (mm) when grinding the workpiece, When the flow rate of the grinding fluid flowing out from the slit between the chips when the warpage amount becomes 0 is F (H) (mm / sec), the following formula (1) is satisfied. It is preferable.
A (H) = C / F (H) (1)

Note that setting so as to satisfy the relationship of the expression (1) means that the total area A (H) of the slits between the chips substantially matches the value in the expression (1). It is not limited to only.
That is, even if the supply flow rate C is set to be controlled to a certain level, some flow rate fluctuation is unavoidable due to the mechanical accuracy of the supply flow rate control, and the allowable value of A (H) also changes slightly. It will be. Further, although the value of F (H) when the warpage amount of the workpiece is 0 is adopted, it goes without saying that the same warpage amount suppressing effect can be obtained if the value is substantially close to 0. That is. Formula (1) is a design guideline for a grinding wheel, and includes designing in a range substantially similar to this.
For example, when the tolerance of the grinding fluid supply flow rate C in the apparatus is set to ± 0.1 L / min, the difference in the flow velocity F (H) generated in the width is estimated to be about ± 10 mm / sec. H) has an allowable range corresponding to such a difference.

Here, F (H) represents the flow rate when the warping amount actually becomes 0 by performing an experiment in which the grinding fluid supply flow rate is finely changed using a grinding wheel having a slit between chips. It may be obtained by measurement.
Further, F (H) may be obtained by estimating a flow rate at which the warpage amount becomes zero based on a plurality of flow rates when the warpage amount does not become zero. For example, as shown in FIG. 3, although the supply flow rate of the grinding fluid was changed at several levels, even when the result that the warping amount was 0 was not obtained, as shown in FIG. An approximate curve of the estimated outflow velocity that becomes the target level can be obtained. From this approximate curve, F (H) may be obtained.
In addition, F (H) calculated | required from the approximated curve of FIG. 4 is represented by the following Numerical formula (2).
F (H) = 122.22 × H ^−0.505 (2)

  According to this invention, the grinding wheel which can obtain the above-mentioned effect can be designed by a simple method which only defines the shape of the chip based on the above formula (1).

The double-headed grinding method of the present invention is a double-headed grinding method of grinding both surfaces of a plate-shaped workpiece using a grinding fluid, and presses the grinding wheel of the above-mentioned grinding wheel on both surfaces of the workpiece. a step of applying, while supplying the grinding fluid into the grinding wheel, characterized in that it comprises a step of grinding the object to be ground.
The method for producing a silicon wafer according to the present invention includes the above-mentioned double-head grinding method for grinding both surfaces of a silicon wafer as a plate-like object to be ground using a grinding liquid.

According to the double-head grinding method and the silicon wafer manufacturing method of the present invention, it is possible to provide an object to be ground and a silicon wafer with stable quality even when chip wear progresses.

It is sectional drawing which shows schematic structure of the double-headed grinding processing apparatus with which the grinding wheel of the experiment example was mounted | worn. It is a side view of the chip | tip of the grinding wheel of the said experimental example. It is a graph which shows the relationship between the supply flow volume of the grinding fluid of the said experimental example, and the quality of a wafer. It is a graph which shows the relationship between the height dimension of the chip | tip of the said experimental example, and the estimated outflow flow velocity of a grinding fluid. It is sectional drawing which shows schematic structure of the double-headed grinding processing apparatus with which the grinding wheel which concerns on one Embodiment (Example) of this invention was mounted | worn. It is a side view of the chip | tip of the grinding wheel of the said one Embodiment (Example). It is a side view of the chip | tip of the grinding wheel which concerns on the modification of this invention. It is a side view of the chip | tip of the grinding wheel which concerns on the other modification of this invention. It is a graph which shows the relationship between the height dimension of a chip | tip in the calculated value based on the grinding wheel and numerical formula of the Example of this invention, and the sum total of a slit area. It is a graph which shows the relationship between the height dimension of the chip | tip of the said Example and a comparative example (the said experimental example), and the estimated outflow flow velocity of a grinding fluid. It is a graph which shows the relationship between the supply flow volume of the grinding fluid of the said Example, and the quality of a wafer.

An embodiment of the present invention will be described with reference to the drawings.
[Configuration of grinding wheel]
As shown in FIG. 5, the grinding wheel 3 applied to the double-head grinding apparatus 1 includes a wheel base 91 and a grindstone 32 formed by bonding abrasive grains with vitrified bonds. As shown in FIG. 6, the grindstone 32 includes an annular grindstone base 321 that is the same as the grindstone base 921, and a plurality of chips 322 that are provided apart from each other along the outer circumferential direction of the grindstone base 321.
Note that the tip 322 may be formed by cutting an annular grindstone, or a press die having a shape corresponding to the grindstone base 321 and the tip 322 is manufactured in advance. It may be formed by filling a material, pressurizing and baking. The grindstone 32 may be other than the vitrified bond type.

  Specifically, the chip 322 is formed in a substantially plate shape, and a trapezoidal plate-shaped chip trapezoidal portion 323 whose width dimension increases as the distance from the grinding wheel base 321 increases, and a rectangular plate shape from the tip of the chip trapezoidal portion 323. The chip rectangular portion 324 extends. Further, the chip 322 is formed such that the distance dimension between adjacent chips 322 (chip distance dimension) is larger on the base end side than on the front end side. With such a configuration, an inter-chip slit S <b> 1 having a width dimension on the proximal end side of the chip 322 larger than that on the distal end side is formed between the grindstone base 321 and the adjacent chips 322. This inter-chip slit S1 includes a slit base end portion S2 whose width dimension becomes smaller as the height position becomes higher, and a slit front end portion S3 whose width dimension is constant regardless of the height position.

The shape of the chip 322 is such that the height of the chip is H (mm), the total area of the slits S1 between the chips is A (H) (mm ² ), and the grinding liquid supplied into the grindstone when grinding the wafer W is used. Adjacent when the supply flow rate is C (mm ³ / sec), the flow rate of the grinding fluid flowing out from the slit S1 between the chips is F (H) (mm / sec), and the supply flow rate C of the grinding fluid is constant. The flow rate F (H) in which the interval dimension between the chips 322 increases due to the change in the height dimension H of the chip 322 that is worn by being subjected to the grinding process, and the flow rate F at which the warpage amount of the wafer W after the grinding process is within a target range. The total area A (H) of the area of the inter-chip slit S1 necessary for lowering to (H) is set.

Specifically, the shape of the chip 322 is set so as to substantially satisfy the following formulas (1) and (2).
A (H) = C / F (H) (1)
H: Height dimension of chip 322 (mm)
A (H): The slit S1 between the chips when the height dimension of the chip 322 is H.
Total area (mm ² )
C: Supply flow rate (mm ³ / sec) of grinding fluid supplied into the grinding wheel when grinding the wafer W
F (H): When the height dimension of the chip 322 is H, the warpage amount of the wafer W is
Flow rate of the grinding fluid flowing out from the slit S1 between the chips when it becomes zero
(Mm / sec)
F (H) = 122.22 × H ^−0.505 (2)

[Double-head grinding method]
Next, a double-headed grinding method using the above-described grinding wheel 3 will be described.
As shown in FIG. 5, two grinding wheels 3 are mounted on the double-head grinding apparatus 1. Then, the grinding wheel 3 is pressed against both surfaces of the wafer W, the grinding liquid is supplied into the grinding wheel 3, and the wafer W is rotated to grind the wafer W. Thereafter, the ground wafer W is replaced with a new wafer W, and the next grinding is performed.

[Effects of Embodiment]
In the present embodiment as described above, the following operational effects can be achieved.
(1) The grinding wheel 3 is formed so that the distance between adjacent chips 322 is larger on the base end side than on the tip end side of the chip 322. For this reason, the slit area when the entire chip rectangular part 324 and a part of the chip trapezoidal part 323 are worn is increased as compared with the case where the distance between the chips 322 is made constant regardless of the height position. Can do. Therefore, the estimated outflow velocity in such a worn state can be made slower than before. Therefore, even when the wear of the chip 322 progresses, the quality of the wafer W can be stabilized. Furthermore, the life of the grinding wheel 3 can be extended.

(2) Moreover, since the grinding wheel 3 is formed so as to substantially satisfy the above formulas (1) and (2), it is possible to easily design the grinding wheel 3 that can obtain the above effects.

[Other Embodiments]
Note that the present invention is not limited to the above-described embodiment, and various improvements and design changes can be made without departing from the scope of the present invention.
That is, the shape of the tip of the grinding wheel may be as shown in FIGS.

As shown in FIG. 7, a chip 322A constituting a grindstone 32A of a grinding wheel 3A includes a trapezoidal chip lower trapezoid part 323A provided on the base end side and a table provided at the tip of the chip lower trapezoid part 323A. It is formed from a chip upper trapezoidal portion 324A having a shape, and is formed in a substantially rectangular plate shape with both corners on the base end side cut out. The height dimension H11 of the chip 322A, the height dimension H12 of the chip lower trapezoidal part 323A, and the height dimension H13 of the chip upper trapezoidal part 324A are set to 12 mm, 3 mm, and 9 mm, respectively. Further, the chip interval dimension D11 on the proximal end side of the adjacent chip lower trapezoidal portion 323A, the chip interval dimension D12 on the distal end side of the chip lower trapezoidal portion 323A, and the chip interval dimension D13 on the distal end side of the chip upper trapezoidal portion 324A are 3 respectively. .5mm, 0.7mm, and 0.5mm.
With such a configuration, an inter-chip slit S11 whose width dimension decreases as the height position increases is formed between the grindstone base 321 and the adjacent chips 322A.

On the other hand, as shown in FIG. 8, the tip 322 </ b> B constituting the grindstone 32 </ b> B of the grinding wheel 3 </ b> B is formed in a trapezoidal plate shape whose width dimension increases from the proximal end toward the distal end. The height dimension H21 of the chip 322B is set to 12 mm. Further, the chip interval dimension D21 on the proximal end side and the chip interval dimension D22 on the distal end side of adjacent chips 322B are set to 3.5 mm and 0.5 mm, respectively.
With such a configuration, an inter-chip slit S21 whose width dimension decreases as the height position increases is formed between the grindstone base 321 and the adjacent chips 322B.

  From the above, also in the grinding wheel 3A shown in FIG. 7 and the grinding wheel 3B shown in FIG. 8, the spacing dimension between the tips 322A and the spacing dimension between the tips 322B are larger on the proximal side than on the distal side. Since it is formed, the quality of the wafer W can be stabilized even if the wear of the chip 322 progresses as in the above embodiment.

  The planar shape of the grindstone is not limited to an annular shape, and may be a polygonal shape such as a triangle or a square. Furthermore, although the double-headed grinding process which grinds both surfaces of the wafer W simultaneously was illustrated, you may use the grinding wheel 3 in the grinding process of only one side of the wafer W. In addition, the object to be ground may be a target other than the wafer W, such as ceramics or stone.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples.

First, a double-head grinding apparatus (DXSG320, manufactured by Koyo Machine Industries Co., Ltd.) having the same configuration as the double-head grinding apparatus 1 used in the above embodiment was prepared.
On the other hand, the grinding wheel 3 as shown in FIG. 6 was prepared as a grinding wheel of an Example. Moreover, the grinding wheel 9 of the experimental example shown in FIG. 2 was prepared as a grinding wheel of a comparative example. The characteristics of the grinding wheels of Examples and Comparative Examples are shown in Table 1 below.

Here, the grinding wheel examples the supply flow rate C of the grinding fluid as 1.6L / min (= 1.6 × 100 3/60 (mm 3 / sec)), the equation (1) and Equation (2 ) To satisfy the following formula (3).
A (H) = (1.6 × 100 ³ /60)/(122.22×H ^−0.505 ) (3)

  As a result, the height dimension H1 of the chip 322 is 12 mm, the height dimension H2 of the chip trapezoidal part 323 is 2 mm, the height dimension H3 of the chip rectangular part 324 is 10 mm, and the chip interval between the base ends of adjacent chip trapezoidal parts 323 The dimension D1 was 3 mm, and the chip interval dimension D2 between adjacent chip rectangular portions 324 was 0.5 mm. As shown in FIG. 9, by setting the shape of the chip 322 in this way, the sum of the slit areas in the grinding wheel of the example and the sum of the slit areas calculated based on the formula (3) substantially coincide. I understand that.

And about the grinding wheel of the Example and the comparative example, the relationship between the height dimension H1 and the presumed outflow velocity of a grinding fluid when the supply flow rate of the grinding fluid was made constant at 1.6 L / min was estimated by calculation. The result is shown in FIG.
As shown in FIG. 10, in the grinding wheel of the example, in addition to the case where the height dimension H1 is 7 mm or more and 12 mm or less, even when the height dimension H1 is less than 7 mm, an approximate curve that changes at a value close to the target level is obtained. It was. For this reason, in the grinding wheel of the embodiment, when all the grinding conditions including the supply flow rate of the grinding fluid are constant and a plurality of wafers W are ground sequentially, the height dimension H1 of the chip 322 is 7 mm or more. Even when the thickness is less than 7 mm, the quality of the wafer W is considered to be stable (Bow-bf is approximately 0 μm).

Then, a silicon wafer having a diameter of 300 mm is prepared by slicing from a silicon single crystal ingot with a wire saw, and grinding fluid (pure water) at a predetermined flow rate is ground using the grinding wheel of each chip height in Examples and Comparative Examples. Grinding was performed so as to be supplied into the wheel and removed by 20 μm each on the front and back surfaces of the silicon wafer. At this time, grinding was performed with the supply flow rate of the grinding fluid set to the 4th or 5th level. In each example and comparative example, the number of wafers to be ground was five, and the average bow-bf of the silicon wafer after grinding was determined.
The result in an Example is shown in FIG. In addition, the result in a comparative example is as having shown as an experimental example in FIG.

In the case of the comparative example, as shown in FIG. 3, when the height dimension H91 is in the range of 3.5 mm to 12.0 mm, the average Bow-bf at a supply flow rate of 1.6 L / min is about −7 μm to about 16 μm. there were.
On the other hand, as shown in FIG. 11, in the case of the embodiment, in the range of the height dimension H1 of 3.0 mm to 12.0 mm, the average Bow-bf at a supply flow rate of 1.6 L / min is about 1 μm It was about 5 μm.
From the above, it was confirmed that the quality of the wafer in the example is more stable and better than that in the comparative example within the same height dimension range. In particular, it was confirmed that even in the case where the height dimension corresponding to the stage where the wear progressed is about 3.0 mm, a high-quality wafer can be provided.

3, 3A, 3B ... Grinding wheel 32, 32A, 32B ... Grinding wheel 322, 322A, 322B ... Chip 91 ... Wheel base W ... Wafer (object to be ground)

Claims (5)

A grinding wheel used for grinding an object to be ground using a grinding fluid,
A substantially plate-like wheelbase,
A wheel that is provided so as to protrude annularly from one surface of the wheel base and is pressed against the workpiece.
The grindstone has a plurality of chips provided along the outer circumferential direction of the ring,
The grinding wheel characterized in that the interval between adjacent chips is set so that the base end side is larger than the tip end side of the chip. The grinding wheel according to claim 1,
Tip height dimension (dimension from the base end to the tip end) is H (mm),
The total area of slits between chips (a region defined by opposing sides of adjacent chips, a line connecting the base ends of the adjacent chips, and a line connecting the tips) is expressed as A (H) (mm ² ),
C (mm ³ / sec), the supply flow rate of the grinding fluid supplied into the grinding wheel when grinding the workpiece
F (H) (mm / sec), the flow rate of the grinding fluid flowing out from the slit between chips,
When the grinding fluid supply flow rate C is constant,
The distance between adjacent chips is as follows:
The flow velocity F (H) that rises due to the change in the height dimension H of the tip that is worn by the grinding treatment is reduced to the flow velocity F (H) that causes the warpage amount of the workpiece to be ground after the grinding treatment to be a target range. The grinding wheel is characterized in that it is set so as to be a total area A (H) of slit-to-chip slits necessary for the above. In the grinding wheel according to claim 1 or 2,
The distance between adjacent chips is as follows:
Tip height dimension (dimension from the base end to the tip end) is H (mm),
In the case where the height dimension of the chip is H (mm), it is defined by an inter-chip slit (a side that faces adjacent chips, a line that connects the base ends of the adjacent chips, and a line that connects the tips. Area) is defined as A (H) (mm ² ),
C (mm ³ / sec), the supply flow rate of the grinding fluid supplied into the grinding wheel when grinding the workpiece
When the chip height dimension is H (mm), the flow rate of the grinding fluid flowing out from the slit between the chips when the warping amount of the workpiece is zero is F (H) (mm / sec),
In this case, the grinding wheel is set so as to satisfy the following expression (1).
A (H) = C / F (H) (1) A double-head grinding method for grinding both sides of a plate-shaped workpiece using a grinding fluid,
Pressing the grinding wheel of the grinding wheel according to any one of claims 1 to 3 against both surfaces of the workpiece;
And a step of grinding the workpiece while supplying a grinding liquid into the grinding wheel.   A method for producing a silicon wafer comprising the double-head grinding method according to claim 4, wherein both surfaces of a silicon wafer as a plate-like object to be ground are ground using a grinding liquid.

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