JP2757086B2 - Wafer separating method and wire saw device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating a wafer cut by a wire saw and a wire saw apparatus to which the method is applied.

[0002]

2. Description of the Related Art For example, in the field of semiconductor manufacturing, a plurality of silicon semiconductor wafers are obtained by thinly cutting a silicon single crystal ingot pulled up by a single crystal pulling apparatus in a direction perpendicular to an axis by an inner peripheral slicer. .

[0003] The recent tendency to increase the diameter of semiconductor wafers has made it difficult to cut ingots using conventional inner peripheral blade slicers. In addition, the cutting method using the inner peripheral blade slicer has a problem in that productivity is poor because the wafer is cut out one by one.

Therefore, a cutting method using a wire saw (particularly, a multi-wire saw) has been attracting attention in recent years.
In this cutting method, a work is pressed against a wire spirally wound between a plurality of rollers, and the wire is moved while supplying slurry to a contact portion between the work and the wire, so that a plurality of wafers are separated from the work. According to this method, a large number of sheets (for example,
00 wafers can be cut out at the same time.

[0005]

After the cutting of the work by the wire is completed by the above-mentioned method, it is necessary to perform a so-called wire removing operation in which the wire is relatively returned along the cutting path of the work.

[0006] In the above wire removal operation, the wire is in a free state without being subjected to the cutting resistance that has been received up to now. However, since the wire is actually affected by tension and vibration, the wire is placed on the wafer surface. It is extremely difficult to smoothly pull out the workpiece along the cutting path without contact, and the problem that the wire hits the wafer surface to cause chipping or chipping of the wafer is likely to occur.

[0007] Therefore, after the cutting of the work is completed, a method is used in which, while holding the wafer row with a separate take-out arm, the backing plate is cut again with a wire and the wafer row is separated from the backing plate (Japanese Patent Application Laid-Open No. 61-1986). No. 182761),
After the cutting of the work is completed, a method in which the plate is further cut with a wire and the wire is bitten into the plate and the wafer is sucked one by one to separate the wafer from the plate (Japanese Patent Application Laid-Open No. SHO 61-61). No. 125767) has been proposed.

However, in the former method, there is a risk that the wafers separated and gripped by the take-out arm fall and come into contact with each other to cause chips and chips, and the latter method requires time and effort to separate. There's a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wafer separating method capable of efficiently separating a plurality of wafers simultaneously without causing chips or chips therein. And a wire saw device.

[0010]

In order to achieve the above object, the present invention provides a vertical descent for lowering a work held on a lower surface of a backing plate with respect to a wire spirally wound between a plurality of rollers. In a wafer separating method applied to a wire saw device that presses a work to a yar and moves a wire while supplying slurry to a contact portion between the work and the wire to cut out a plurality of wafers from the work. , A liquid storage tank in which liquid is stored
Is placed below the wire and directly below the work, and after cutting of the work by the wire is completed, the contact plate is further lowered so that the wire is bitten into the corresponding plate by a predetermined depth. The plate is moved in a direction perpendicular to the moving direction of the wire and in a horizontal direction, and the wafer is separated from the caul plate together with a part of the caul plate, and the separated cuff is moved.
It is characterized in that the aerial falls naturally into the liquid in the liquid reservoir .

[0011] Further, in the above wire saw apparatus, straight the backing plate with respect to the moving direction of the wire
The contact plate drive means that can be moved in the angular and horizontal directions
And a liquid storage tank in which a liquid is stored inside the tank.
It is provided below the ear and directly below the work .

[0012]

According to the present invention, the cutting of the workpiece by the wire is completed.
After that, lower the contact plate further and apply the wire to the plate
To the specified depth, and from this state wipe the backing plate
Moves in a direction perpendicular to the direction of movement
The wafer with a part of the backing plate
Cut off from the board. And all the separated wafers
There is a reservoir just below the wire and below the wire.
Therefore, these separated wafers are liquid
Drops (natural fall) into the liquid in the reservoir. For this reason, the conventional wire removing operation becomes unnecessary, and all the wafers can be cut off efficiently at the same time without generating chips or chips. If a buffer material such as urethane foam is attached to the inner surface of the liquid reservoir, the impact of the wafer falling into the liquid can be reduced to prevent chips and chips from being generated on the wafer. Further, it can be prevented more reliably.

[0013]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 4 are sectional views showing a wafer separating method according to the present invention in the order of steps, FIG. 5 is a perspective view of a wire saw body of a wire saw apparatus according to the present invention, and FIG.
Is a cutaway side view of a roller end, and FIG. 7 is a cross-sectional view showing a work of cutting a work by a wire saw device.

First, the configuration of the wire saw main body 1 will be described with reference to FIG. 5. The wire saw main body 1 has three rollers 2, 3, and 4 arranged at respective apexes of a triangle in a parallel and rotatable manner. And these rollers 2, 3,
A single wire 5 made of a special piano wire having a wire diameter of about 0.08 to 0.25 mm is spirally wound between the four at a predetermined pitch.

A work W such as a single crystal ingot is placed on a work cutting jig 7 via a backing plate 6 between the upper two rollers 2 and 3 and above the rollers 2 and 3. The work W is held and set, and the work W moves up and down together with the work cutting jig 7 when the work cutting jig 7 is moved up and down by driving means (not shown). The backing plate is made of a material such as glass, ceramic, and graphite, and the work W
Is held in an attitude such that the orientation flat Wa faces directly below. The backing plate 6 is moved in the direction a in the drawing ( that is, the direction of movement of the wire 5 stretched between the rollers 2 and 3 (in the direction of the arrow b in the drawing)).
(A right angle direction and a horizontal direction with respect to ) is connected.

The lower roller 4 is a driving roller, which is rotated forward and backward by a driving motor 9.

The configuration of the end of the roller 2 is shown in FIG. 6. The roller 2 is formed by press-fitting a hollow resin cylinder 11 into a core metal 10 made of cast iron. The main body frame 13 is rotatably supported via a bearing 12. Grooves 14 are spirally formed on the outer periphery of the resin cylinder 11 at a predetermined pitch (desired wafer thickness + cut allowance), and the wire 5 is fitted into the grooves 14. Although the configuration of the roller 2 has been particularly described above, the configuration of the other rollers 3 and 4 is the same as that of the roller 2.

Further, as shown in FIG.
A nozzle 16 for ejecting a slurry (abrasive liquid) 15 (see FIG. 7) is provided above the roller, and a pair of rollers 2 and 3 is provided.
A slurry reservoir 17 for receiving the slurry 15 ejected from the nozzle 16 is provided in the gap (immediately below the workpiece W and immediately below the wire 5), and an inner surface of the slurry reservoir 17 has a predetermined thickness (for example, In the embodiment, a cushioning material 18 (see FIG. 4) such as urethane foam of 10 mm) is attached. The slurry 15 is a mixture of lapping abrasive grains and a grinding fluid, and is stored in a slurry tank (not shown).

Next, the operation of the wire saw device will be described.

The wire saw apparatus according to the present embodiment is an apparatus employing a vertical descent method for moving a work W vertically downward. In the wire saw body 1, a work cutting jig 7 is provided via a backing plate 6. The workpiece W held by the wire 5 moves downward, and the wire W is stretched between the rollers 2 and 3.
Is pressed. Then, in this state, when the drive motor 9 is driven and the drive roller 4 is alternately rotated forward and backward, and the slurry 15 is supplied from the nozzle 16 to the contact portion between the work W and the wire 5, as shown in FIG. As described above, the work W is cut to a predetermined thickness by the lapping action of the wire 5 and the slurry 15 that reciprocate (see FIG. 1).

Then, as shown in FIG. 2, even after the cutting of the work W by the wire 5 is completed and a plurality of wafers Wi are cut out from the work W, the contact plate 6 is further lowered and the wire 5 In this state, the contact plate driving means 8 is driven to move the contact plate 6 in the moving direction of the wire 5 as shown in FIG.
(Perpendicular to the plane of FIG. 3) and water
In the horizontal direction (the direction of the arrow a in FIG. 3), a predetermined amount (the amount that maximizes the arrangement pitch of the wires 5 (1.5 mm in this embodiment)) is a predetermined speed (0.2 to 0. 5mm
/ Min), as shown in FIG. 4, all the wafers Wi are cut off from the backing plate 6 integrally with the part 6a of the backing plate 6, and the weight in the slurry storage tank 17 is simultaneously reduced by its own weight.
It falls into rally 15. The wafer Wi falling into the slurry 15 has the buffering action of the slurry 15,
The buffer material 18 stuck on the inner surface of the slurry reservoir 17
The shock is absorbed and alleviated by the buffering action of.

As described above, according to the present embodiment, the wafer Wi is separated by the wire 5 together with the part 6a of the backing plate 6, and all the separated wafers Wi fall naturally by their own weight and the slurry in the slurry pool 17 is removed. Because it is put into the inside of 15, the conventional wire removal work becomes unnecessary,
All the wafers Wi can be simultaneously and efficiently separated without generating chips or chips. As described above, the wafer Wi charged into the slurry 15
Is subjected to a buffering action by the slurry 15 and the buffer material 18, so that the impact applied thereto is suppressed to a small extent, and the generation of chips and chips on the wafer Wi is more reliably prevented. By the way, in the conventional method (a method including a wire removing operation), the rate of occurrence of chips and chips in the wafer is 8%, whereas in the method of the present invention (when no buffer material is attached to the slurry reservoir), It was suppressed to as low as 3%, and could be reduced to 0% particularly when a buffer material was attached to the slurry reservoir.

[0024]

As is apparent from the above description, according to the present invention, the workpiece held on the lower surface of the backing plate is lowered vertically with respect to the wire spirally wound between the plurality of rollers. In a wafer separating method applied to a wire saw device which presses a work to a wire and feeds a slurry to a contact portion between the work and the wire to move the wire and cut out a plurality of wafers from the work. , A liquid storage tank in which liquid is stored
It is arranged below the wire and directly below the work, and after the cutting of the work by the wire is completed, the caul plate is further lowered so that the wire is bitten into the corresponding plate by a predetermined depth, and from this state the caul plate disconnection from perpendicular direction, and abutting with part in the horizontal direction by moving against the wafer plate plate with respect to the moving direction of the wire, detached weather
Since the wafers are allowed to fall naturally into the liquid in the liquid storage tank, an effect is obtained in which a plurality of wafers can be cut off efficiently simultaneously without generating chips or chips.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a wafer separating method according to the present invention in the order of steps.

FIG. 2 is a sectional view showing a wafer separating method according to the present invention in the order of steps.

FIG. 3 is a sectional view showing a wafer separating method according to the present invention in the order of steps.

FIG. 4 is a sectional view showing a wafer separating method according to the present invention in the order of steps.

FIG. 5 is a perspective view of a wire saw main body of the wire saw device according to the present invention.

FIG. 6 is a cutaway side view of a roller end.

FIG. 7 is a cross-sectional view showing a work of cutting a work by a wire saw device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire saw main body 2, 3, 4 Roller 5 Wire 6 Backing plate 6a Part of backing plate 8 Backing plate drive means 17 Slurry storage tank (liquid storage tank) 18 Buffer material

Claims (3)

(57) [Claims] 1. A vertical descent method in which a work held on a lower surface of a backing plate is lowered with respect to a wire spirally wound between a plurality of rollers, and the work is pressed against a wire to press the work. A method applied to a wire saw device that cuts a plurality of wafers from a work by moving a wire while supplying a slurry to a contact portion of the wire, wherein the liquid is stored in a liquid reservoir tank. Wai
Yer lower, and directly under the workpiece, after the cutting of the workpiece by the wire has been completed, caul plate was further lowered by bite a predetermined depth into the plate wire Te applicable, the plate against this state At right angles to the direction of wire movement
In a horizontal and horizontal direction to separate the wafer from the caul plate with a part of the caul plate, and
A method for separating a wafer, wherein the wafer is dropped naturally into the liquid in the liquid storage tank . 2. A vertical descent method in which a work held on a lower surface of a backing plate is lowered with respect to a wire spirally wound between a plurality of rollers, and the work is pressed against a wire to press the work. In a wire saw device that cuts a plurality of wafers from a work by moving a wire while supplying slurry to a contact portion between the wire and a wire, the contact plate is moved in a direction perpendicular to the moving direction of the wire and horizontally.
Provide a contact plate drive means for moving the
The liquid storage tank in which
A wire saw device provided immediately below one work . 3. The wire saw device according to claim 2, wherein the liquid storage tank is a slurry storage tank, and a buffer material having a predetermined thickness is adhered to an inner surface of the slurry storage tank.