JP2554424Y2 - Inner circumference grinding wheel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an inner peripheral grindstone used for cutting a wafer from a semiconductor ingot, and more particularly to an improvement for stabilizing the warpage of the cut wafer. .

"Prior art" This kind of inner peripheral blade grindstone forms an abrasive grain layer 2 in which diamond abrasive grains are fixed by a metal plating phase on the inner peripheral edge of a thin annular base metal 1 as shown in FIG. The outer peripheral edge is mounted on a driving device via an annular fixing jig, and is used for use.

In the conventional inner peripheral blade grindstone, the abrasive grain layer 2 has a tear-shaped cross section as shown in FIG.
Is set to 2 to 3 mm, and the tolerance is set to about 0.2 mm. The thickness T of the abrasive layer is usually set to about TD + 0.15 mm of the thickness of the base metal.

In the case of manufacturing this grindstone, the following method has been employed so far. That is, after a cylindrical shaft is inserted into the opening of the base 1, an annular jig having a width of 2 to 3 mm is mounted on the shaft, and the jig is placed on the inner periphery of the base 1. Affix the masking tape to the base 1 along. Do this for both sides of the base 1 and 2-3mm from the inner periphery of the base
Exposed portions are formed over the width, and the abrasive layer 2 is electrodeposited on these exposed portions. Because of this manufacturing method,
The width W and the tolerance of the abrasive layer 2 were limited to the above values due to restrictions on accuracy.

"Problems to be solved by the invention" By the way, when cutting a thin wafer from a single crystal ingot using an inner peripheral grindstone, all the wafers are convex within 10 μm toward the inner peripheral grindstone. It is desired that the wafer be warped. However, in the above-described conventional inner peripheral edge grindstone, the degree of warpage of the wafer varies, and in some cases, the wafer may be warped positively. However, when the wafer is warped in this way, the coolant around the wafer deteriorates during the cutting, and the cooling liquid blows out from the wafer during the cutting, which damages the wafer and damages the base metal of the inner peripheral grindstone. This causes problems such as shortening the life of the grindstone,
There is a disadvantage that wafer productivity is significantly impaired.

Therefore, the inventors of the present invention have conducted detailed studies on the above-described phenomenon, and as a result of repeating cutting experiments with variously changing the dimensions of each part of the inner peripheral grindstone, particularly when the width W of the abrasive layer 2 is reduced, This led to the discovery of a new fact that the warpage of the wafer is stabilized. In that case, the abrasive layer width W
It has been found that it is essential to reduce the tolerance of, and when the dimensions are determined, an extremely good warpage stabilizing effect can be obtained if the width W is set to 0.5 mm or less and the tolerance is set to 50 μm or less. I understood.

"Means for solving the problem" The present invention has been made based on the above findings, and the width of the abrasive layer in the base metal radial direction is set to 0.5 mm or less,
The width tolerance is suppressed to 50 μm or less.

[Operation] The reason why the warpage of the wafer is stabilized is considered as follows. In other words, by making the radial width of the abrasive layer smaller than before, the surface area of both side portions that are not directly involved in cutting on the surface of the abrasive layer becomes smaller, so that the work material and these both side portions are Frictional resistance is reduced. At the same time, the contact area between the abrasive layer and the work material is reduced, so that chips generated on the cut surface due to cutting can be quickly discharged from the contact surface, and the remaining chips on the contact surface This can prevent an increase in frictional resistance and unevenness. Therefore, the fluctuation of the base metal caused by the deterioration of the balance of the frictional resistance is reduced, the cutting direction of the grindstone is stabilized, and a wafer having an appropriate minus warpage can be cut out. The problems of cracking and shortening the life of the grinding wheel can be improved.

Embodiment FIG. 1 is a cross-sectional view of an abrasive grain layer of an inner peripheral grindstone according to the present invention.

This inner peripheral blade grindstone has an abrasive grain layer 11 formed by fixing superabrasive grains such as diamond or CBN with a metal plating phase such as Ni on the inner peripheral edge of a thin annular plate-shaped base metal 10 over the entire circumference. Therefore, they are formed so as to have the same tear-shaped cross section.

The width W of the abrasive layer 11 in the base metal radial direction is set to 0.5 mm or less. If the width W is larger than 0.5 mm, the die 1
The run-out of 0 becomes large, and the warpage of the cut wafer does not become constant. The lower limit of the width W is determined in consideration of the bonding strength of the abrasive layer 11 to the base metal 10 and the life of the grinding wheel.

Further, the tolerance of the width W is required to be smaller than that of the conventional product as the width W is reduced, and specifically, must be set to 50 μm or less. If it is larger than 50 μm, the cutting resistance becomes non-uniform in the circumferential direction, the run-out of the base metal 10 occurs, and the cutting accuracy decreases.

Furthermore, the width from the inner peripheral edge of the abrasive grain layer 11 to the thickest point is W1,
Assuming that the width from the thickest point to the outer edge is W2, the ratio of both is
It is desirable that W1: W2 = 1: 1 to 1: 3. If the thickest point is displaced to the inner peripheral side or the outer peripheral side beyond this range, in any case, the chipping becomes poor during cutting and the cutting accuracy is reduced.

On the other hand, the thickness T of the abrasive layer 11 is equal to the thickness TD of the base metal 10+ (0.12
~ 0.20) mm is desirable. If the thickness is smaller than this range, the work material and the base metal 10 may come into contact with each other during cutting, and the cutting resistance may increase.If the thickness is larger than the above range, the cutting margin of the work material increases and waste of the work material is increased. Occurs.

In order to manufacture the inner peripheral grindstone, the following manufacturing method is suitable instead of the conventional masking method with low accuracy.

After attaching a masking tape with an adhesive to the inner peripheral edge of the base metal 10 and setting the base metal on an auto drafter or an NC processing device equipped with a cutter, apply the masking tape along a position corresponding to the outer peripheral edge of the abrasive layer. Cutting with high precision using a cutter. At that time, it is necessary to strictly control the cut amount so as not to damage the base metal 10 with the cutter. Next, the masking tape on the inner peripheral edge of the base metal 10 is peeled off, and the abrasive layer 11 is electrodeposited on the exposed portion.

After the photoresist is applied to the base 10, the photoresist is set in an exposure apparatus, exposed and developed with ultraviolet rays to remove the photoresist only at the inner peripheral edge of the base 10, and an abrasive layer 11 is applied to the exposed portion. To wear.

According to the inner peripheral grindstone having the above-described configuration, the radial width of the abrasive layer 11 is made smaller than in the related art, so that the surface of the abrasive layer 11 is not directly involved in cutting as shown in FIG. Since the area of the side portions P is reduced, the frictional resistance between the workpiece and the side portions P is reduced. at the same time,
Since the contact area between the abrasive layer 11 and the work material H is reduced, chips generated by cutting are quickly discharged from the contact surface,
It is possible to prevent an increase in frictional resistance and non-uniformity due to residual chips on the contact surface. Therefore, the fluctuation of the base metal 10 caused by the deterioration of the frictional resistance balance is reduced, the cutting direction of the grindstone is stabilized, and a wafer having an appropriate minus warpage can be cut out, and the finishing of the wafer in the next process is simplified. And the processing cost can be reduced accordingly. Further, it is possible to prevent the wafer from being cracked during cutting due to the instability of the warp, prevent the base metal from being damaged, and extend the life of the grindstone.

Furthermore, with this inner peripheral blade, the cutting resistance is reduced,
There is also an advantage that the rotational driving force of the grindstone can be small and the amount of generated frictional heat can be reduced.

[Effects of the Invention] As described above, according to the inner peripheral grindstone according to the present invention, since the area of both sides of the surface of the abrasive grain layer that are not directly involved in cutting is reduced, the work material and the Friction resistance with both side parts is reduced. At the same time, the contact area between the abrasive grain layer and the work material is reduced, so that chips generated by cutting are quickly discharged from the contact surface, thereby preventing an increase in frictional resistance and non-uniformity due to residual chips. be able to. Therefore, the fluctuation of the base metal caused by the deterioration of the balance of the frictional resistance is reduced, and the cutting progress direction of the grindstone is stabilized,
A wafer having an appropriate minus warpage can be cut out, and the finishing of the wafer in the next step can be simplified, and the processing cost can be reduced accordingly. Further, it is possible to prevent the wafer from being cracked during cutting due to the instability of the warp, prevent the base metal from being damaged, and extend the life of the grindstone.

Furthermore, with this inner peripheral blade, the cutting resistance is reduced,
There is also an advantage that the rotational driving force of the grindstone can be small and the amount of generated frictional heat can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an abrasive layer of an inner peripheral grindstone according to the present invention,
FIG. 2 is a cross-sectional view showing the effect of the grindstone, FIG. 3 is a plan view of a general inner peripheral grindstone, and FIG. 4 is a cross-sectional view of an abrasive layer of a conventional inner peripheral grindstone. 10: base metal, 11: abrasive layer, W: width of the abrasive layer in the base metal radial direction.

Claims (1)

(57) [Scope of request for utility model registration] 1. An inner peripheral grindstone in which an abrasive layer formed by fixing superabrasive grains with a metal plating phase is electrodeposited on an inner peripheral edge of a thin annular base metal, wherein the base metal radius of the abrasive layer An inner peripheral grinding wheel characterized in that the width in the direction is set to 0.5 mm or less and the width tolerance is suppressed to 50 μm or less.