JPH04169205A - Cutting method by multiwire saw - Google Patents

Abstract

PURPOSE:To recover wafers after cutting in an extremely efficient manner by attracting and fixing a work by magnetic force in addition to an adhesive. CONSTITUTION:A primary dummy plate 8 made of a fragile material is bonded to the under surface of a work 6 and a secondary dummy plate 18 made of a magnetic material is bonded to the under surface of the dummy plate 8 and a tertiary dummy plate 28 made of a magnet is interposed between the dummy plate 18 and the steel base on a work push-up stand 10. In this state, the work 6 is attracted and fixed by magnetic force to be cut and, at the point of time when the dummy plate 28 is cut by wires 4, cutting is stopped. Subsequently, wafers 6-1 having the cut pieces of the dummy plates 8, 18 bonded thereto are separated from the dummy plate 28. By this method, the wafers 6-1 after the cutting of the work 6 can be efficiently taken out and the mounting of the work 6 can be also simply and rapidly carried out and the rate of operation of a multiwire saw can be markedly enhanced and there is no anxiety generating a saw mark at all when the wafers are taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a multi-wire saw for cutting brittle materials such as semiconductor materials, magnetic materials, and ceramics into a large number of thin wafers using wires. This invention relates to a cutting method that allows a wafer to be taken out simply, quickly, and efficiently after cutting is completed.

Conventional technology For example, a multi-wire saw used to cut silicon ingots of semiconductor electronic materials into wafer shapes presses a workpiece against a row of wires strung at a predetermined pitch and uses a grinding fluid containing abrasive grains (hereinafter referred to as abrasive fluid). This is a device that allows the wire and workpiece to move relative to each other while pouring the workpiece, and cuts the wire and workpiece using a grinding action.

Figure 6 shows an example of the cutting section of a general multi-wire saw, in which three groove rollers (IX2
A single wire (
4) is wound to form a wire row (5) at a predetermined pitch, and this wire row is run while pouring abrasive liquid while pushing up a workpiece lifting table to gradually cut the workpiece.

In this method, the workpiece (6) is attached to a steel base (9) with adhesive via a dummy plate (8) made of brittle material.In other words, the workpiece (6) is attached to the bottom surface of the workpiece (6) with adhesive. A dummy plate (8) is glued, and this dummy plate is glued to the base (9) with adhesive.The base (9) can be attached to and detached from the workpiece lifting table (10) using screws (11). mounted on.

In the method of using adhesive to fix the workpiece, the adhesive must of course withstand the grinding force caused by the running of the wire row (5), and epoxy adhesives, wax, etc. are usually used. Ru.

FIG. 7 (AXB) shows an enlarged view of the cutting section of the wire saw, and the push-up of the workpiece (6) is performed by the wire row (
5) is continued until the dummy plate is cut, and the workpiece (6) is cut into a large number of wafers (6-1). Also, at this time, the wire row (5) is connected to the dummy plate (
8), and the space between the cut wafers is filled with abrasive grains (12).

Conventionally, there are the following methods for taking out a cut wafer from a wire saw.

The first method is to move the wire row shown in FIG. 7(A) to the workpiece (
6), loosen the screws (11), remove the base (9) from the push-up table (10), and pull out the wires (4) remaining in the workpiece (6) one by one. It is.

The second method is to keep the push-up table (1o) stopped, run the wire (4 loaves), pull out the wire (4) from the workpiece (6), and remove the base (9) from the push-up table (1o). .

The third method is to move the wire row (5) from the state shown in FIG. 7(A).
After lowering the push-up table (10) while running at a low speed and pulling out the wire row (5) above the workpiece (6),
This method is to remove the entire base (9) from the push-up table (10).

A fourth method is to wash and remove abrasive grains (12) stuck between wafers while leaving the wire array (5) in the dummy plate (8), as shown in Japanese Patent Application Laid-Open No. 12576/1983. death,
This is a method in which the wafers (6-1) are broken off one by one from the edge using a suction pad.

The fifth method, as shown in Japanese Unexamined Patent Publication No. 61-182761, is to grasp both side surfaces of the workpiece (6) along its entire length in the state shown in FIG. 7(A), and tighten the screws (11).
is loosened, and while the wire row (5) is running, the base (9) is gradually slid by a separate drive device (not shown), and the dummy plate (8) is cut across by the wire row (5). This is a method of taking out all wafers at once.

Problems to be Solved by the Invention However, the first to fifth methods have the following problems.

The first method is convenient when the wire is disposed of after being cut once, but results in a large loss when the wire is only slightly damaged and can be reused. Another problem is that it takes a lot of man-hours to set the wire on the wire saw again.

The second method allows the wire to be reused, but has the disadvantage that winding takes time if there is a large amount of wire remaining at the time the cutting is completed. Also, like the first method, there is a drawback that it takes a lot of man-hours to set the wire on the wire saw again.

The third method has the advantage that the wire row remains in the wire saw, so another workpiece can be cut subsequently, and the wire saw can be operated efficiently, but the workpiece is lowered. During the process, saw marks may be created on the wafer surface.

In other words, there is no problem if the cut surface of the wafer is sufficiently flat and vertical, but if these conditions are not met, the wire row will rub against the cut surface and the workpiece will descend, resulting in saw marks. It is. Depending on the severity of the saw mark, the wafer may have to be discarded.

In the fourth method, although there is no concern about saw marks, if the workpiece is fragile, there is a possibility that the wafer itself may be broken without being broken at the position of the dummy plate. Another drawback is that when there are a large number of wafers, it takes time to take out the wafers.

Note that the first to third methods also require a step of breaking off the work pieces one by one from a group of wafers that must be removed from the wire saw, and like the fourth method, there are problems with wafer breakage and man-hours. Needless to say.

The fifth method is efficient because all the wafers are taken out at once, but there are problems in that the device is complicated and the manufacturing cost is high.

This invention was made in order to solve the above-mentioned problems related to taking out wafers after cutting with a wire saw, and it is possible to very efficiently collect wafers after cutting with a relatively simple means, and to improve the operation of a multi-wire saw. This paper attempts to propose a cutting method that can improve the cutting rate.

Means for Solving the Problems The cutting method according to the present invention adopts a method of attracting and fixing the workpiece using magnetic force in addition to adhesive instead of the conventional method using only adhesive. .

That is, the gist of this invention is to bond a primary dummy plate made of a brittle material to the lower surface of a workpiece, bond a secondary dummy plate made of a magnetic material to the lower surface of the primary dummy plate, and connect the secondary dummy plate and the workpiece to Cutting is performed with a tertiary dummy plate made of magnet interposed between the steel base on the table and fixed by magnetic force. Cutting is stopped when the wire cuts into the tertiary dummy plate, and the wire is cut into the tertiary dummy plate. In this method, the wafer to which the cut pieces of the secondary dummy plate and the cut pieces of the secondary dummy plate are bonded is separated from the tertiary dummy plate.

Further, the present invention is characterized in that in the above cutting method, the primary dummy plate is omitted and a secondary dummy plate made of a magnetic material is bonded to the lower surface of the workpiece, and the tertiary dummy plate is used in the same manner as the secondary dummy plate. It is made of a magnetic material, and is characterized in that the tertiary dummy plate and the secondary dummy plate are attracted and fixed to a base made of a magnet.

Operation In this invention, the primary dummy plate is made of brittle materials such as ceramics and glass as in the past, but the secondary dummy plate is magnetically attached to the steel base on the workpiece lifting table via the tertiary dummy plate made of magnets. Because it is fixed by suction, it is made of soft magnetic material such as steel plate.

In the case of this method of fixing a workpiece through a dummy plate having a so-called three-layer structure, the secondary dummy plate is also cut with a wire, so it is desirable that the thickness of the secondary dummy plate be thin in order to shorten the cutting time. Usually, a thickness of around 0.5 mm is appropriate.

Needless to say, the magnetic adsorption force of the tertiary dummy plate is strong enough to prevent the workpiece from being displaced by the force in the wire running direction that acts on the workpiece during cutting.

If the wire cuts all the way to the tertiary dummy plate, the completely cut secondary dummy plate is attracted to the tertiary dummy plate by magnetic force, and the space between the wafers is filled with abrasive grains, so the wafers may fall over. There isn't.

To take out the wafer, the wafer can be easily separated from the tertiary dummy plate with the primary dummy plate and the secondary dummy plate attached by simply sliding the wafer in a direction perpendicular to the cutting direction. Therefore, the removal of wafers is not limited to one wafer at a time;
It is also possible to take out several dozen sheets at once.

If the primary dummy plate is omitted and the secondary dummy plate is bonded directly to the workpiece, the wafer after cutting is separated from the tertiary dummy plate with the cut pieces of the secondary dummy plate attached.

In addition, in the case of a method in which the tertiary dummy board is made of magnetic material and fixed to a magnetic base like the secondary dummy board, the secondary dummy board and the tertiary dummy board are both attracted at the same time by the magnetic force of the magnetic base. . Therefore, the wafer after cutting is separated from the tertiary dummy plate with the cut pieces of the primary dummy plate and the secondary dummy plate attached.

Needless to say, the suction force of the base in this case is strong enough to prevent the workpiece from being displaced by the force in the wire running direction that acts on the workpiece during cutting.

In any of the above methods, the wire rows are inserted into the cut grooves of the tertiary dummy plate as they are, so it is possible to repeatedly cut the workpiece with the same tertiary dummy plate, making it extremely easy to load the workpiece onto the wire saw and take out the wafer. It can be done efficiently.

Embodiment Example 1 Figures 1 to 3 show an embodiment corresponding to claim 1 of the present invention, and Figure 1 (A) is a front view showing a state in which a workpiece with a dummy material is set on a wire saw. Figure, Figure 1 (B)
is a side view of the same as above, FIG. 2(A) is a front view showing the state in which the wire has been cut to the tertiary dummy plate, FIG. 2(B) is a side view of the same as above, and FIG. 3 is after removing the wafer with a wire saw. This is a diagram showing the state in which the wire row is removed from the workpiece lifting platform.
A) is a front view, and (B) is a side view.

That is, in FIGS. 1 and 2, a dummy plate (8) made of a brittle material is glued to the lower surface of a workpiece (6), and a secondary dummy plate (18) made of a magnetic material is glued to the lower surface of this primary dummy plate. A tertiary dummy plate (28) made of a magnet is interposed between this secondary dummy plate and the steel base (9), and fixed on the workpiece lifting table (10).

Here, the primary dummy plate (8) is made of a brittle material such as ceramics or glass as in the conventional method.

The secondary dummy plate (18) is a wire saw workpiece lifting table (
10) Since it is fixed by magnetic force, it is manufactured from a soft magnetic material such as a steel plate. Further, since this secondary dummy plate (18) is also cut with a wire, it is better to have a thinner thickness in order to shorten the cutting time. However, if the surface of the secondary dummy plate (18) after adhering to the primary dummy plate (8) is not flat, the magnetic restraining force will be weakened, so the thickness of the secondary dummy plate (18) should be kept to an extreme. It cannot be made thinner. When using a steel plate, a thickness of around 0.5 mm is appropriate.

The tertiary dummy plate (28) is made of hard magnetic material. It goes without saying that the magnetic adsorption force of this tertiary dummy plate (16) is strong enough to prevent the workpiece (6) from shifting due to the force in the wire running direction that acts on the workpiece (6) during cutting as described above. Nor.

Regarding the planar dimensions of the primary dummy plate (8) and the secondary dummy plate (18), the length in the longitudinal direction must be at least the same as the length of the workpiece (6), but the width must be the same as that of the workpiece (6) during cutting.
There is no problem even if the width is narrower than the workpiece (6) as long as it has the ability to securely hold the workpiece (6).

The workpiece (6) is cut in the same way as in the past, by running the wire row (5) stretched at predetermined intervals and raising the workpiece lifting table (10) while pouring abrasive liquid.

゛ A force in the wire running direction is applied to the workpiece (6) being cut by the wire row (5), but the tertiary dummy plate (2
Since it has a force sufficient to withstand not only the magnetic attraction force (8) but also the force in the wire running direction, the workpiece will not shift or move unstablely.

The cutting progresses in this manner and stops when the wire row (5) cuts halfway into the tertiary dummy plate (28), as shown in FIG.

The workpiece (6) has many wafers (6-1) except for both ends.
, the primary dummy plate (8) and the secondary dummy plate (18) are cut into respective cut pieces (8-IX18-1). Even in this state, the secondary dummy plate cut piece (18-1) is attracted by the tertiary dummy plate (28 lbs.) magnetic force, and the space between the wafers (6-1) is filled with abrasive grains, so the wafer (6-1) will not fall.

When taking out the wafer, after stopping the running of the wire (1), remove the cut pieces of the primary and secondary dummy plates (8-1) (18-1).
) is separated from the tertiary dummy plate (28).

This operation can be easily performed by moving the wafer (6-1) in the direction of arrow A shown in FIG. 2(B).

Furthermore, since it is possible to separate several dozen sheets at once, there is no problem in terms of man-hours. Incidentally, if the abrasive grains stuck between the wafers (6-1) are removed in advance using a cleaning liquid such as kerosene, this separation work will be made easier. Finally, the dummy plate cut piece (8-IX18-
A product wafer is obtained by removing 1) from the bonded portion.

Figure 3 shows that after all wafers (6-1) have been removed from the tertiary dummy plate (28), the push-up table (10) is lowered and the wire row (5) is moved into the groove (28-1) of the tertiary dummy plate (28). Shows the state in which Oki-ra has been detached.

When cutting again from this state, the workpiece shown in Figure 1 (
6), primary dummy plate (8) and secondary dummy plate (18)
Connect the adhesive part to the used tertiary dummy board (
28).

At the end of the cutting process, the wire row (5) is again placed in the groove (28-1) of the tertiary dummy plate (28), so if the pitch of the wires (1) in the wire row (5) is the same, the cutting operation can be carried out. This process can be carried out repeatedly, and loading the workpiece onto the wire saw and taking out the wafer can be done extremely efficiently.

In addition, here, a flat tertiary dummy plate (1
6), but grooves of specified dimensions and pitch (2
8-1) A tertiary dummy plate made of magnet (2)
If 8) can be manufactured, it can be used from the first cutting.

Embodiment 2 FIG. 4 shows an embodiment corresponding to claim 2 of the present invention, in which the primary dummy plate (8) is omitted and the secondary dummy plate (18) is bonded directly to the lower surface of the workpiece (6). This is the method of cutting.

In this case, after the wire row (5) is cut halfway into the tertiary dummy plate (28), the cut piece of the secondary dummy plate (18-1
) is attached to the wafer (6-1>) on a tertiary dummy plate (
28).

This method can also be carried out by repeating the cutting operation using the same tertiary dummy plate, as long as the wire pinch of the wire row (5) is the same, as described above. It is also possible to form the grooves formed in the first cutting on the tertiary dummy plate (28) in advance.

Embodiment 3 FIG. 5 shows an embodiment corresponding to claim 3 of the present invention, which is a cutting method in which the base (9) has the function of a magnetic chuck of a machine tool such as a surface grinder.

That is, in this method, the base (9) is made of a magnet, the tertiary dummy plate (28) is made of a magnetic material like the secondary dummy plate (18), and the tertiary dummy plate (38) is made of a secondary dummy plate (
18) This is a method of adsorbing and fixing both to a magnetic base (19).

In the case of this method, a secondary dummy plate (18) made of magnetic material is bonded to a secondary dummy plate (8) bonded to the workpiece (6), and this secondary dummy plate (18) and a magnetic base (19) are bonded. In this method, a tertiary dummy plate (38) made of a magnetic material is interposed between the two dummy plates (38), and the tertiary dummy plate (38) and the secondary dummy plate (18) are attracted by the magnetic force of the magnet base (19).

Therefore, as in the case of Example 1, the wafer cut by this method is attached to the tertiary dummy plate with the primary dummy plate cut piece (8-1) and the secondary dummy plate cut piece (18-1) adhered to each other. Separate from (38).

Similar to the above method, if the wire pitch of the wire rows is the same, the cutting operation can be repeated using the same tertiary dummy plate, and the grooves formed in the first cutting can be cut into the tertiary dummy plate in advance. It goes without saying that it is also possible to form the same.

In addition, although the above-mentioned Examples 1 to 3 show workpieces having a rectangular cross-section, it goes without saying that the present invention is not limited to a rectangular cross-section and can be applied to any other cross-sectional shape.

For example, in the case of a workpiece with a circular cross section, a primary dummy plate or a secondary dummy plate having one side of a curved surface equivalent to the outer circumferential curvature of the workpiece may be bonded to the workpiece.

Example 4 Width 100 mm, length 210 mm, thickness 10 on the bottom surface of a 100 mm square, 210 mm long quartz ingot (work)
A primary glass dummy plate (8) with a diameter of 100 mm in width, 210 mm in length, and 0.6 m in thickness is glued on the bottom surface of the primary glass dummy plate (8).
A secondary dummy plate made of mild steel with a diameter of 0 m was glued, and the secondary dummy plate was suctioned and fixed to a tertiary dummy plate made of ferrite magnet, which was suctioned and fixed on a steel base attached to a push-up stand of a multi-wire saw. .While running a wire row made of 2mm wires stretched at a pitch of 2mm, an abrasive solution containing green carborundum #600 abrasive grains is supplied, and the push-up table is raised to remove the workpiece, primary dummy plate, and secondary dummy plate. was cut, and when the wire was cut into the tertiary dummy plate by about 3 mm, the wire was stopped running and the lifting table was stopped.

After that, remove the abrasive grains between the wafers with kerosene and remove the thickness. 1.7
A wafer of mm in diameter was separated from the tertiary dummy plate with the primary and secondary dummy plate cuts attached, and the primary and secondary dummy plate cut pieces were removed to obtain 100 product wafers.

At that time, it took 8 minutes to take out all the wafers from the wire saw after cutting was completed.

On the other hand, for comparison, the seventh dummy material was glued to the base.
As a result of cutting the same workpiece using the conventional method shown in the figure, it took about 2 hours to remove all the wafers. Furthermore, in the process of lowering the push-up table, saw marks are generated by the wire on the cut surface of some wafers, and those with significant saw marks had to be discarded.

Therefore, it is clear that according to the method of the present invention, not only the number of man-hours for taking out wafers is significantly reduced, but also wafers of good quality can be obtained.

Example 5 In Example 4, the primary glass dummy plate was omitted, the secondary dummy plate was directly adhered to the quartz ingot, and the wafers with a thickness of 1.7 mm were cut under the same conditions as in Example 4. The secondary dummy plate was separated from the tertiary dummy plate with the cut pieces attached to it, and 100 product wafers were obtained.

It took 8 minutes to take out all the wafers from the wire saw after cutting was completed.

Example 6 i! A silicon ingot with a diameter of 125 mm and a length of 185 mm has a width of 800 mm, a length of 185 mm, and a center thickness of 15 mm.
A primary dummy plate made of ceramic with a diameter of 80 mm was glued, and a secondary dummy plate made of a mild steel plate with a thickness of 0.5 mm was glued to the underside of the dummy plate, and the width was 80 mm, which was attracted to a magnetic base attached to the push-up stand of a multi-wire saw. Length 185mm, thickness 6
The secondary dummy plate was adsorbed onto a tertiary dummy plate made of a mild steel plate with a diameter of 0.16 mm and a pitch of 0.9 mm.
Supplying an abrasive solution containing green carborundum #1000 abrasive grains while running a wire row stretched at
The push-up table is raised to cut the workpiece, the primary dummy plate, and the secondary dummy plate, and when about 3 mm has been cut into the tertiary dummy plate, the running of the wire and the lifting of the push-up table are stopped.
Thereafter, 200 wafers with a thickness of 0.7 mm were separated from the tertiary dummy plate, and the cut pieces of the primary dummy plate and the cut pieces of the secondary dummy plate attached to the wafers were removed to obtain product wafers.

At that time, it took 9 minutes to take out all the wafers from the wire saw after cutting was completed.

On the other hand, when the same silicon ingot was cut using the conventional method, it took about 70 minutes to take out all the wafers.

As described in detail, according to the method of the present invention, the wafer after cutting the workpiece with the multi-wire saw can be efficiently taken out, and the workpiece can also be mounted simply and quickly. In addition to being able to significantly improve the operating rate, there is no need to worry about saw marks occurring when taking out wafers, so it has the great effect of allowing high-quality wafers to be manufactured with high efficiency.

[Brief explanation of the drawing]

1 to 3 are views showing an embodiment corresponding to claim 1 of the present invention, and FIG. 1 (A) is a front view showing a state in which a workpiece with a dummy material is set on a wire saw, and ) is a side view of the same as above, FIG. 2(A) is a front view showing the state in which the wire has been cut to the tertiary dummy plate, FIG. 2(B) is a side view of the same as above, and FIG. FIG. 4 is a diagram showing a state in which the wire row is removed from the workpiece lifting table, where (A) is a front view, (B) is a side view, and FIG. 4 is claim 2 of the present invention.
FIG. 5 is an embodiment corresponding to claim 3 of the present invention, and is a front view showing a state in which a workpiece with dummy material is set on a wire saw. FIG. 6 is a perspective view illustrating the cutting section of a multi-wire saw used for boat fishing, and FIG. 7 is an enlarged view of the workpiece and lifting platform of the same wire saw. FIG. 3B is an enlarged perspective view showing a state in which the dummy material has been cut, and FIG. 3B is an enlarged side view showing the wafer portion. l, 2.3...Groove roller 4...Wire 5.
...Wire row 6--Work 6-1...Wafer 8...Primary dummy plate 9...Base 10...Pushing table 18
...Secondary dummy plate 19...Magnetic base 2
8.38...Tertiary dummy board Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Yoshihisa Oshida, Aiko □ Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 (A) So (B)

Claims (1)

[Scope of Claims] 1. A processing liquid containing abrasive grains is supplied between a traveling wire and an object to be cut, and a large number of wafers are In a multi-wire saw that cuts the object, a primary dummy plate made of a brittle material is bonded to the bottom surface of the object to be cut, a secondary dummy plate made of a magnetic material is bonded to the bottom surface of the primary dummy plate, and the secondary dummy plate and Cutting is performed with a tertiary dummy plate made of a magnet interposed between the steel base on the workpiece lifting table and fixed by magnetic force. Cutting is stopped when the wire cuts into the tertiary dummy plate, and the primary dummy plate is fixed. A cutting method using a multi-wire saw, characterized in that a wafer to be cut, to which a cut piece of a plate and a cut piece of a secondary dummy plate are adhered, is separated from a tertiary dummy plate. 2. A cutting method using a multi-wire saw according to claim 1, characterized in that the primary dummy plate is omitted and a secondary dummy plate made of a magnetic material is bonded to the lower surface of the object to be cut. 3. A cutting method using a multi-wire saw according to claim 1, characterized in that the tertiary dummy plate is made of a magnetic material, and the tertiary dummy plate and the secondary dummy plate are attracted and fixed to a magnetic base.