JP5366135B2 - Thin wafer processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an excellent cutting surface with a high yield by stopping the vibration of a large number of thin wafers at a cutting start side during the cutting of a work while preventing the generation of a crack by the vibration of the wafers and a saw mark. <P>SOLUTION: In a method of cutting the work 3 by a wire 2 of a wire saw 1 into the large number of thin wafers 5, the work 3 is fixed to the cutting finish side, an incision plate 9 is adhered to a cutting start surface of the work 3 before cutting of the work 3 starts, cutting by the wire 2 is started with the incision plate 9 being a cutting start position, the cutting of the incision plate 9 is stopped once during the cutting of the incision plate 9, the surface of the incision plate 9 at the cutting start position is washed, a fixing plate 11 is thereafter adhered to the surface of the incision plate 9 at the cutting start position, and thereby the large number of thin wafers 5 are fixed to the cutting start side also. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to a method of manufacturing a large number of thin wafers from a workpiece such as a silicon ingot by cutting using a wire saw.

The wire saw relatively moves the workpiece and the wire row in the running state, and presses the wire row against the surface on the cutting start side of the workpiece, thereby cutting the workpiece into a large number of thin wafers having a predetermined thickness. As the cutting progresses, the wire row forms cutting grooves on the surface on the cutting start side of the workpiece, and these cutting grooves are extended to the fixed side of the workpiece.

Normally, thin wafers are held only on the fixed side, so as the cutting grooves extend, they are subject to vibration during cutting and are likely to swing in the direction perpendicular to the cut surface of the wafer on the cut side. . As a result of this deflection, the thin wafer is bent or broken during the cutting process, and a saw mark is formed on the cut surface of the wafer, so that a smooth surface cannot be formed.

In addition, in a wire saw to which slurry (abrasive liquid containing free abrasive grains) is supplied at the time of cutting, the slurry enters the cutting groove, and the adjacent wafer entrains and adheres to the cutting surface. This adhesion state makes handling of the wafer after cutting, especially separation work and alignment storage work difficult.

On the other hand, in the technique of Patent Document 1, in order to eliminate the difficult work described above, an elastic material or a soft material is filled on the opening side of the cutting groove in the middle of cutting the workpiece, and the wafer swings or vibrates. Is suppressed. However, even with this technique, the wafer is not fixed sufficiently on the cutting start side. In addition, when filling the cutting groove during cutting, external force in the folding direction is likely to act between thin wafers, so the filling operation is actually performed unless the work is actually cut and then carefully cut. In an ideal state, it cannot be filled. Further, once the cutting of the workpiece is stopped, saw marks are formed on the cut surface of the wafer, and a good cut surface cannot be obtained.

JP 2002-205255 A

Therefore, it is an object of the present invention to enable a large number of thin wafers to be steady even at the cutting start side during workpiece cutting, to prevent cracking due to wafer vibration and generation of saw marks, and to obtain a good cut surface with a high yield. Is to get.

Based on the above problems, the present invention is a method of cutting a workpiece into a plurality of thin wafers by a wire row of a wire saw, fixing the workpiece on the cutting end side, and starting cutting the workpiece before starting cutting the workpiece. The cutting plate is bonded to the surface, and the cutting by the wire row is started with the cutting plate as the cutting start position, and fixed to the cutting start surface of the cutting plate during the cutting of the cutting plate. A plurality of thin wafers can be fixed on the cutting start position side of the cutting plate by bonding the working plate.

Further, the present invention provides a method of cutting a workpiece into a plurality of thin wafers by a wire row of a wire saw, fixing the workpiece on the cutting end side, and providing a cutting plate on the cutting start surface of the workpiece before starting the cutting of the workpiece. Adhesion is started, and cutting with the wire row is started with the cutting plate as a cutting start position. During the cutting of the cutting plate, cutting of the cutting plate is temporarily interrupted, and cutting of the cutting plate is started. A plurality of thin wafers can be fixed even at the cutting start position side by adhering a fixing plate to the surface of the cutting start position of the cutting plate after cleaning the position surface (claim 2). .

The fixing plate may be fixed to the wire saw side (claim 3).

According to the thin wafer processing method of the present invention, a large number of thin wafers are fixed by the fixing plate even on the cutting start position side, and during cutting, each wafer is held at both end positions in the cutting direction. Each wafer does not vibrate, the wafer is less bent and cracked due to the vibration, and the generation of saw marks can be prevented in advance, so that a thin wafer can be cut with a high yield (claim 1).

Further, according to the thin wafer processing method of the present invention, a large number of thin wafers are fixed by the fixing plate even on the cutting start position side, and during the cutting, each wafer is held at both end positions in the cutting direction. In addition to the above effects that each wafer does not vibrate, the bending and cracking of the wafer due to vibration are reduced, and the generation of saw marks can be prevented in advance, so that thin wafers can be cut with high yield, Since the cutting is interrupted and the cutting plate is washed during the cutting of the cutting plate, the bonding between the cutting plate and the fixing plate is ensured, and the above effect is further enhanced (claim 2).

When the fixing plate is fixed to the wire saw side, the part to be a workpiece or a thin wafer is held in a so-called both-end supported state at both ends in the cutting direction with respect to the work table of the wire saw, for example. The fixing is further ensured (Claim 3).

It is a side view of the positional relationship between a wire and a workpiece when the wire traveling direction of the wire saw is viewed as left and right. It is a side view of the positional relationship of a wire and a workpiece | work seeing from the wire traveling direction of a wire saw. It is a side view of the state in the middle of cut | disconnecting the plate for cutting of a workpiece | work with a wire row | line based on the processing method of the thin wafer of this invention. It is a side view of the state which adhered the plate for fixation to the surface of the cutting start position of the plate for cutting based on the processing method of the thin wafer of the present invention. It is an enlarged side view of the state in the middle of the cutting | disconnection of the cutting plate, and the state which adhere | attached the fixing plate on the surface of the cutting start position of the cutting plate. It is a side view of the state which completed the cutting | disconnection of the workpiece | work based on the processing method of the thin wafer of this invention.

1 and 2 show the positional relationship between the wire 2 of the wire saw 1 and the workpiece 3 when the thin wafer processing method of the present invention is carried out. In these FIG. 1 and FIG. 2, the wire saw 1, as an example, runs multiple wires 2 wound between two parallel grooved main rollers 4, and silicon is placed in a row of cutting areas of the wires 2. The workpiece 3 is cut into a large number of thin wafers 5 by relatively pressing the workpiece 3 such as an ingot.

Each groove 4a of the main roller 4 is a V-shaped annular groove as shown in the enlarged sectional view in the circle of FIG. 2, and is formed independently of each other on the outer peripheral surface of the main roller 4 corresponding to the wire pitch. Yes. The wires 2 are parallel to each other in the cutting region facing the workpiece 3, that is, in the upper region in the illustrated example, in the corresponding grooves 4 a of the two main rollers 4, and with respect to the center line of the main roller 4. Are wound in a non-cutting area that does not face the workpiece 3, that is, in a state where the groove 4a is displaced from the adjacent groove 4a to the other groove 4a in the lower region in the illustrated example. That is, the roller 4 is skewed with respect to the center line.

In this example, the upper surface of the workpiece 3, that is, the surface on the cutting end side is a fixed side with respect to the wire saw 1, and is fixed to a glass co-cutting holder 7 by an adhesive layer 6. And is attached to a work table (not shown) of the wire saw 1 by appropriate clamping means (not shown).

As shown in FIGS. 1 and 2, the thin wafer processing method of the present invention is provided with a heat-fusible plate 9 on the cutting start surface of the workpiece 3, on the lower surface in this example, before the cutting of the workpiece 3 is started. While being adhered by the adhesive layer 10 and supplying slurry (not shown) to the cutting position as necessary, the lower surface of the cutting plate 9 is used as a cutting start position as shown in FIG. The cutting of the plate 9 is started, and while the cutting plate 9 is being cut, for example, about half the thickness of the cutting plate 9 is cut, the cutting of the cutting plate 9 is temporarily interrupted, as shown by the solid line in FIG. In addition, the cutting plate 9 is washed while the wire 2 is positioned in the cutting groove 13 of the cutting plate 9.

Even if a saw mark is formed on the cut surface of the cutting plate 9 due to the interruption of the cutting of the cutting plate 9, the saw mark is not a cutting surface of the workpiece 3, that is, a cutting surface of the product wafer 5. There is no impact on quality.

The cutting plate 9 is cleaned by removing slurry and chips from the lower surface of the cutting plate 9 and the cutting groove 13 of the cutting plate 9 and then bonding the fixing plate 11 to the lower surface of the cutting plate 9. It is done to make it in good condition. As an example, the cutting plate 9 is made of glass like the co-cutting holder 7 and has a thickness of about 1 to 2 mm.

After the cleaning, the thin wafer processing method according to the present invention is as shown in FIG. 4 and as indicated by an imaginary line in FIG. Then, the cutting of the cutting plate 9 is resumed while supplying a slurry (not shown) as necessary, and the cutting of the workpiece 3 is continued following the cutting plate 9 as shown in FIG. Finally, it cuts to about half the thickness of the co-cutting holder 7.

As the cutting process proceeds, a cutting groove 13 is formed in the cutting plate 9, the work 3 and the co-cutting holder 7, and when the cutting groove 13 reaches the middle of the thickness of the co-cutting holder 7, the work 3 is completely Are cut into a plurality of thin wafers 5. At this point, the cutting operation is complete.

In the middle of the cutting, a portion to be a large number of thin wafers 5 is fixed to the co-cutting holder 7 through the uncut workpiece 3 at one end and fixed to the fixing plate 11 through the cutting plate 9 at the other end. It is fixed. For this reason, during cutting, the portion that should become the thin wafer 5 is held at both ends, so that it hardly vibrates during the cutting operation, does not break or crack due to vibration, and No saw mark is generated. Such an effect is continued from the beginning of cutting to the point of completion of cutting.

The fixing plate 11 may be attached to a work table (not shown) of the wire saw 1 by an appropriate bracket (not shown). In this way, since the part to be the workpiece 3 and the thin wafer 5 is held in a so-called both-end supported state at both ends in the cutting direction with respect to the work table (not shown) of the wire saw 1, It will be even more certain.

In the above specific example, in the middle of cutting of the cutting plate 9, the cutting of the cutting plate 9 is temporarily interrupted, the surface at the cutting start position of the cutting plate 9 is washed, and then the cutting of the cutting plate 9 is started. The fixing plate 11 is bonded to the position surface. However, the interruption of the cutting with respect to the cutting plate 9 and the cleaning of the surface at the cutting start position are not necessarily required and can be omitted.

As illustrated in FIG. 1, a plurality of air injection nozzles 14 are arranged on the side of the cutting plate 9 toward the cutting start surface, and cutting with the wire 2 is continued, or the traveling speed of the wire 2 The air jet nozzle 14 blows air onto the cutting start surface of the cutting plate 9 while lowering the pressure, and blows off the slurry and swarf on the surface, thereby bonding the epoxy resin with water-curing property or wet surface bonding performance. The fixing plate 11 can be bonded to the cutting start surface of the cutting plate 9 using an adhesive or pressure-sensitive (adhesive) adhesive layer 12. Even if there is no air injection, the installation of the air injection nozzle 14 can be omitted if the fixing plate 11 adheres to the cutting start surface of the cutting plate 9 with a required strength. The air injection nozzle 14 can be replaced with a wiping means using a nonwoven fabric or a woven fabric.

Note that the workpiece 3 may not be above the wire 2 but below the wire 2. When the wire 2 is on the workpiece 3 and the cutting plate 9 is not present, when the wire 2 cuts the workpiece 3, the portion that becomes the thin wafer 5 opens and subtracts at the upper end during the cutting, Cutting cannot be continued as it is, but if the upper ends of the portions to be the wafers 5 are held by the cutting plate 9, those upper ends are not opened. Therefore, cutting can be continued as it is.

As described above, when the workpiece 3 is below the wire 2, the slurry 15 and the chips are less likely to appear on the upper surface of the cutting plate 9, that is, the cutting start surface. The fixing plate 11 is in a state where it can be relatively easily adhered to the cutting start surface of the cutting plate 9.

Moreover, the workpiece | work 3 may be a cylindrical body instead of a hexahedron. In the cylindrical work 3, if the surface of the cutting plate 9 is a cylindrical surface, it is advantageous because the adhesion between the cylindrical surface and the cylindrical work 3 is stabilized.

In the above specific example, one workpiece 3 is cut, but the cutting can be performed on a plurality of workpieces 3 at the same time. In that case, the cutting plate 9 and the fixing plate 11 may be provided for each workpiece 3 or may be provided as a common one for the plurality of workpieces 3.

DESCRIPTION OF SYMBOLS 1 Wire saw 2 Wire 3 Workpiece 4 Main roller 4a Groove 5 Wafer 6 Adhesive layer 7 Joint cutting holder 8 Base plate 9 Cutting plate 10 Adhesive layer 11 Fixing plate 12 Adhesive layer 13 Cutting groove 14 Air injection nozzle

Claims (3)

In a method of cutting a workpiece into a number of thin wafers by a wire row of a wire saw, the workpiece is fixed on the cutting end side, and a cutting plate is adhered to the cutting start surface of the workpiece before starting the cutting of the workpiece. A number of thin wafers are obtained by starting cutting with a wire row using the cutting plate as a cutting start position, and bonding the fixing plate to the surface of the cutting plate at the cutting start position in the middle of cutting the cutting plate. Is fixed also on the cutting start position side of the cutting plate. In a method of cutting a workpiece into a number of thin wafers by a wire row of a wire saw, the workpiece is fixed on the cutting end side, and a cutting plate is adhered to the cutting start surface of the workpiece before starting the cutting of the workpiece. The cutting with the wire plate is started with the cutting plate as the cutting start position, and the cutting of the cutting plate is temporarily interrupted during the cutting of the cutting plate, and the surface at the cutting start position of the cutting plate is cleaned. A thin wafer processing method characterized in that a large number of thin wafers are also fixed on the cutting start position side by bonding a fixing plate to the surface of the cutting start position of the cutting plate. 3. The thin wafer processing method according to claim 1, wherein the fixing plate is fixed to the wire saw side.

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