JP3434801B2 - Method for manufacturing beveling wheel for processing peripheral portion of silicon wafer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beveling wheel for processing an outer peripheral portion of a silicon wafer and a method for manufacturing the beveling wheel.

[0002]

2. Description of the Related Art In the process of processing a silicon wafer, a silicon ingot is formed into a cylindrical ingot of a predetermined size with an outer peripheral blade or a cup type wheel, and this cylindrical ingot is formed into a predetermined thickness with an inner peripheral blade. The basic process is to slice the wafer into wafers, chamfer the periphery of the wafer with a beveling wheel, and then lap, etch, and polish the wafer surface to complete the integrated circuit substrate. .

In the above-mentioned processing steps, the beveling wheel for the outer peripheral portion of the wafer is chamfered and ground by using a beveling wheel as shown in FIGS. 3 and 4, and as shown in FIG. Processing is performed.

FIG. 3A is a perspective view showing an example of the appearance of the beveling wheel, and FIG. 3B is a partially enlarged view of the outer peripheral portion. An abrasive grain layer 102 having one or a plurality of grooves formed on the outer periphery of a base metal 101 is fixed to the wheel 100 (FIG. 3 shows an example of a plurality of grooves). Base metal 101
Is an iron disc-shaped base metal, and the abrasive grain layer 102 is an abrasive grain layer composed of diamond abrasive grains and metal bonds.

FIG. 4 is a diagram showing an example of the groove shape of the abrasive grain layer of the beveling wheel. (A) is an example in which one groove 103a is formed, (b) is a groove 103b for roughing and finishing. An example in which a plurality of grooves 103c are formed respectively, and (c) shows an example in which a plurality of the same grooves 103d are formed.

FIG. 5A is a diagram showing an example of a method for grinding the outer peripheral portion of a silicon wafer, and FIG. 5B is a diagram showing the outer peripheral shape of the silicon wafer after processing. In the process of processing silicon wafers, the edge of the outer peripheral end face is sharp when the wafer is still cut, and chipping is likely to occur during handling work in each processing step. Or, scratches, cracks, or the like may occur, leading to a reduction in yield of semiconductor devices. For this reason, a beveling process is performed to scrape off the edge portion of the outer peripheral end surface of the wafer. This beveling process is
As shown in FIG. 5A, the wafer 200 is held by the vacuum chuck 300, and the wafer 200 and the wheel 100 are held.
Is rotated to grind the outer peripheral portion into a shape as shown in FIG.

[0007]

In the beveling wheel for processing the outer peripheral portion of the silicon wafer as described above, a metal bond has been conventionally used as a bond for forming an abrasive grain layer. For this metal bond, copper,
Powder of a simple metal or alloy of tin and cobalt is used, and a mixture of this metal powder and abrasive grains is filled in a mold and then sintered at 700 to 900 ° C to fix the abrasive grain layer to the base metal. Let This sintering method is based on iron (eg S2
5C to S45C) a base metal, and a molding mixture of metal powder and abrasive grains is pressed and sintered in a heated state to directly fix the abrasive layer to the base metal.

However, a conventional beveling wheel using an iron base metal has a large wheel weight, and the workability of mounting and removing it on a polishing machine is not good. In addition, there is a problem that water, which is a grinding liquid used during grinding, causes rust on the iron base metal and contaminates the silicon wafer. To prevent rusting of the base metal, it is possible to apply Ni plating to an iron base metal or use a stainless steel base metal, but Ni plating is not perfect for rust prevention. Also, stainless steel has high material cost and weight,
There is a problem that the adhesiveness of the abrasive grain layer is also low.

To solve this problem, it is conceivable to replace the iron base metal with an aluminum or aluminum alloy base metal. However, when the base metal is made of aluminum or aluminum alloy, aluminum or aluminum alloy cannot withstand the sintering temperature in the sintering process of fixing the abrasive grain layer to the base metal, so direct fixing by sintering is adopted. Can not do it. Therefore, instead of directly fixing by sintering, it is possible to fix it with an adhesive, but the adhesive mainly composed of conventional epoxy resin used in general superabrasive wheels etc. is electrically conductive due to its composition. Therefore, it cannot be used for fixing the abrasive layer to the beveling wheel. In the abrasive grain layer of the beveling wheel, electric discharge machining is performed for forming the above-mentioned groove, but it is preferable that the electric discharge machined product has a low electric resistance (specific resistance). If the specific resistance becomes 1 × 10 ³ Ω · cm or more, heat will be generated and processing problems will occur, so this specific resistance is 1 × 10 3.
It is preferably ² Ω · cm or less, and an adhesive having no conductivity generates heat during electric discharge machining and is not suitable for fixing an abrasive grain layer to a beveling wheel.

The problem to be solved by the present invention is to make the adhesive for fixing the abrasive grain layer of the beveling wheel conductive and to make it possible to employ a base metal made of light metal or a light metal alloy. , To reduce the weight of the beveling wheel.

[0011]

The present invention relates to a beveling wheel for processing an outer peripheral portion of a silicon wafer, in which an abrasive grain layer having one or a plurality of grooves formed on the outer peripheral portion of a base metal is fixed. The base metal is a base metal made of aluminum or an aluminum alloy, the abrasive grain layer is an abrasive grain layer using a metal bond or a conductive resin bond as a binder, and the base metal is provided via an adhesive containing a metal powder. The abrasive grain layer is fixed to the above.

By using an adhesive containing an appropriate amount of metal powder as the adhesive for fixing the abrasive grain layer to the base metal, the adhesive can be made conductive, and the base metal has an abrasive grain layer. It is possible to secure the electrical conductivity of 1 × 10 ² Ω · cm or less suitable for performing the electric discharge machining for forming the groove of the abrasive grain layer after the fixing. In addition, by fixing the abrasive grain layer to the base metal with an adhesive, it is not necessary to use a complicated molding die integrated with the base metal as in the past, and a die with only the abrasive grain layer is necessary. The manufacturing cost can be reduced. Further, a base metal made of aluminum or aluminum alloy can be adopted as the base metal, and the weight reduction of the beveling wheel can be achieved.

As the adhesive, 50 to 8 of metal powder is used.
An epoxy resin-based adhesive containing 0% by weight is suitable.
As the metal powder, powder of iron, aluminum, copper, tin or the like having an average particle diameter of 2 to 50 μm can be used. iron,
The adhesive can be made conductive by incorporating a metal powder such as aluminum, copper, or tin into the epoxy resin. Here, if the content of the metal powder is less than 50% by weight, the specific resistance of the adhesive is 1 × 10 ³ Ω · cm or more, and electrical conductivity capable of electrical discharge machining cannot be obtained.
If the content is more than wt%, the adhesive ability will decrease, so the content is preferably within the above range. The average particle size of the metal powder is 2 μm
If it is smaller, the manufacturing cost of the metal powder increases,
When it is larger than m, the interval between the metal particles is widened to hinder the conductivity, and the specific resistance becomes 1 × 10 ³ Ω · cm or more and heat is generated during electric discharge machining.

The above-mentioned beveling wheel has a step of producing an annular abrasive grain layer using a metal bond or a conductive resin bond as a binder by using a die, and an outer peripheral portion of a base metal made of aluminum or aluminum alloy. By a manufacturing method including a step of fixing the annular abrasive grain layer via an electrically conductive adhesive, and a step of forming one or more grooves by electric discharge machining in the abrasive grain layer fixed to the base metal It can be manufactured.

[0015]

1 is a partial sectional view showing a beveling wheel according to an embodiment of the present invention. A bevelling wheel (hereinafter, referred to as a wheel) 10 has a disc-shaped base metal 1 and a grooved abrasive grain layer 2 fixed to an outer peripheral portion of the base metal 1. The base metal 1 is made of an aluminum alloy and has an outer diameter of about 200 mm and an outer peripheral thickness of about 15 mm. The abrasive grain layer 2 is composed of diamond abrasive grains and a metal bond, and is adhered to the base metal 1 by a method described later, and then 1 by electrical discharge machining.
The groove 3 of the strip is formed.

FIG. 2 is a view showing a manufacturing process of the wheel of FIG. 1, (a) shows an abrasive grain layer before being adhered to a base metal,
(B) shows the step of adhering the abrasive grain layer to the base metal, and (c) shows the state after the adhering of the abrasive grain layer to the base metal and before the groove formation.

The ring-shaped abrasive grain layer 2a shown in FIG.
It is produced by the same manufacturing method as the abrasive grain layer of a general rim type wheel, and it is filled with a mixture of a metal bond consisting of metal powder and diamond abrasive grains in a predetermined mold, and it is heated under pressure. It is made by firing at. The ring-shaped abrasive grain layer 2a has a ring width of about 3 mm and a ring thickness of about 8 mm.

As shown in FIG. 2 (b), the outer periphery of the base metal 1 has a divided structure for fitting the ring-shaped abrasive grain layer 2a, and is divided from the main body 1a connected to the main body of the base metal 1. Part 1
It is divided into b and. When the ring-shaped abrasive grain layer 2a is fitted, the divided portion 1b is removed from the main body 1 of the base metal 1, and the contact surface between the main body portion 1a and the divided portion 1b and the ring-shaped abrasive grain are formed between the main body portion 1a and the divided portion 1b. Adhesive 4 (shown by diagonal lines in the figure) is applied to the surface in contact with the layer 2a, and the divided portion 1b is brought into close contact with the main body 1a with the ring-shaped abrasive grain layer 2a placed on the stepped portion of the main body 1a As a result, the ring-shaped abrasive grain layer 2a is fixed to the outer peripheral portion of the base metal 1 as shown in FIG.

In the step of FIG. 2 (b), the main body 1a on the outer peripheral portion of the base metal 1 and the divided portion 1b and the ring-shaped abrasive grain layer 2a.
In the present embodiment, as the adhesive 4 for adhering, the adhesive used is an epoxy resin containing 60% by weight of copper powder having an average particle diameter of 10 μm. Conductivity is imparted to the adhesive by incorporating copper powder in the epoxy resin, and the particle size is 10 μm.
When containing 50% by weight of copper powder of m, the specific resistance is about 5 ×
It becomes 10 ² Ω · cm, which is approximately 1 × 10 ² Ω · cm when it is contained at 60% by weight, and approximately 2 when it is contained at 80% by weight.
It becomes 0 Ω · cm. When the content of copper powder is 40% by weight, the specific resistance is about 1 × 10 ⁴ Ω · cm, and when the content of copper powder is less than 50% by weight, the specific resistance lower than 1 × 10 ³ Ω · cm is obtained. I can't.

After that, the ring-shaped abrasive grain layer 2 is formed by electric discharge machining.
A groove 3 having a sectional shape shown in FIG. 1 is formed in a. The method of forming the groove 3 by electric discharge machining can be performed by a method similar to the conventional method. In this embodiment, the groove 3 having the shape shown in FIG. 1 is formed, but it goes without saying that the shapes of the abrasive grain layer and the groove can be various shapes including the shape shown in FIG. Absent.

Table 1 shows the physical properties of the epoxy resin adhesive containing copper powder used in this embodiment together with the conventional adhesive without copper powder.

[Table 1]

As can be seen from Table 1, the bending strength gradually decreases with an increase in the addition amount of the copper powder, but in practice, the adhesive strength shown in Table 2 is more important. Refer to physical properties. Regarding the bending elastic modulus, increasing the amount of copper powder added increases the bending elastic modulus and improves the rigidity of receiving the abrasive grain layer, improving the sharpness when processing silicon wafers and reducing chipping, which is the cause of defects. Becomes

Table 2 shows the measurement results of the adhesive strength between the base metal and the typical abrasive grain layer (copper, tin-based metal bond) using the epoxy resin adhesive containing copper powder used in this embodiment.

[Table 2]

As shown in Table 2, the adhesive strength when the metal bond abrasive grain layer is adhered to the base metal of two kinds of aluminum castings using the epoxy resin adhesive containing copper powder is 25 to 45 Mpa.
It is slightly lower than that of the carbon steel (S45C) base metal, but the result of the rotation test with the wheel shape shows that even when it is rotated at a peripheral speed three times the normal peripheral speed. It was confirmed that there was no problem and the adhesive strength was practically sufficient.

[Test Example] A silicon wafer processing test was carried out using the wheel (invention product) of the above embodiment and a wheel (conventional product) in which a metal bond abrasive grain layer was directly adhered to an S45C base metal. Processing conditions Wheel specifications: SD600N125M60 Wheel dimensions: 202 ^φ × 20 ^T × 30 ^H Wheel peripheral speed: 1800 m / min Working allowance: Approx. 0.4 mm Work material: 150 ^φ Silicon wafer

The test results are shown in Table 3.

[Table 3]

In the wheel of the invention, since the abrasive grain layer is fixed to the base metal via the adhesive containing copper powder and having a high flexural modulus, the wheel has a high rigidity to receive the abrasive grain layer and is excellent in processing the silicon wafer. The sharpness was improved and chipping caused by defects was reduced, and the defect rate was reduced by 50% compared to the conventional product.

[0028]

EFFECTS OF THE INVENTION By attaching an abrasive grain layer using a metal bond or a conductive resin bond as a binder to an aluminum or aluminum alloy base metal through an adhesive containing an appropriate amount of metal powder, the base metal It is possible to secure conductivity suitable for performing electric discharge machining for forming a groove in the abrasive grain layer after fixing the abrasive grain layer to, and at the same time achieve weight reduction. Further, since it is not necessary to use a complicated molding die integrated with a base metal as in the conventional case, and a die having only an abrasive grain layer is required, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a beveling wheel according to an embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process of the bevelling wheel of FIG.

FIG. 3 is a diagram showing an example of the overall shape of a bevelling wheel.

FIG. 4 is a diagram showing an example of the form of grooves in an abrasive grain layer of a beveling wheel.

FIG. 5 is a diagram showing an example of grinding processing using a beveling wheel.

[Explanation of symbols]

1 unit 1a main body 1b Dividing part 2 Abrasive layer 2a Ring-shaped abrasive grain layer 3 grooves 4 adhesive 10 wheels

Continuation of front page (51) Int.Cl. ⁷ identification code FI B24D 5/00 B24D 5/00 P (56) References JP-A-6-226637 (JP, A) JP-A-2000-94334 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B24D 3/00 310 B24D 3/00 340 B24D 3/00 350 B24D 3/34 B24D 5/00

Claims (2)

(57) [Claims] 1. A metal bond or conductivity using a mold.
A process for manufacturing an annular abrasive grain layer using resin bond as a binder
And base metal made of aluminum or aluminum alloy
The ring-shaped abrasive is attached to the outer periphery of the
The process of fixing the grain layer and the abrasive grain layer fixed to the base metal
A step of forming a single or multiple grooves by electric discharge machining
Beveling wheel for silicon wafer outer peripheral processing including
Manufacturing method. 2. A metal as the conductive adhesive.
A resin containing 50 to 80% by weight of powder is used.
Beveling wheel for processing the outer peripheral portion of a silicon wafer
Manufacturing method.