JP2003291056A - Wire cutting method for any object, cutting wire, and manufacturing method for wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire cutting method for any object to be cut, a cutting wire and a manufacturing method for the wire, capable of enhancing the cutting efficiency and accuracy of the object and suppressing generation of a wire severance. <P>SOLUTION: If the surface of the wire 11a is roughened to a certain degree or more, the retaining force of free abrasive grains b to the wire surface is heightened, and the amount of attachment of the free abrasive grains b to the wire surface is increased. Therefore, the cutting efficiency and accuracy are enhanced when cutting an ingot I by the wire 11a whereto a large quantity of the free abrasive grains b are attached. This suppresses unevenness of the wafer thickness and a warp of each wafer and also suppresses generation of the wire severance. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cutting a wire to be cut, a wire for cutting, and a method of manufacturing the wire, and more specifically, adjusting the surface roughness of the wire to a certain degree or more so as to allow free grinding to the wire surface. TECHNICAL FIELD The present invention relates to a method for cutting a wire to cut an object to be cut by increasing the holding power of grains, a wire for cutting, and a method for manufacturing the wire.

[0002]

2. Description of the Related Art A wire saw has a structure in which a wire for cutting an ingot derived from a bobbin for feeding out a wire is wound around a plurality of groove rollers in a coil shape and wound around a bobbin for winding the wire. Has been done. In the groove roller, the outer peripheral surface of a cylindrical base metal is covered with a lining material (urethane rubber) having a predetermined thickness, and a large number of wire grooves are formed on the outer peripheral surface of the lining material. The groove roller is rotatably supported by a pair of bearings arranged at both ends in the axial direction of the groove roller. At the time of cutting the ingot, while supplying the slurry-like abrasive liquid containing loose abrasive grains (abrasive grains) in the lapping oil, the single crystal silicon ingot is relatively moved with respect to the wire train that is reciprocating at high speed. Press down. The grinding action of the abrasive grains cuts the ingot into a large number of wafers.

[0003]

By the way, in the conventional wire, the surface roughness is 0.01 in terms of arithmetic average roughness Ra value.
It was as small as about μm, and its surface was smooth. Therefore, it was difficult for the abrasive grains to adhere to the surface of the wire when the ingot was cut. As a result, the cutting efficiency of the ingot is lowered and the cutting accuracy is lowered, and unevenness of the wafer thickness and warp of the wafer occur. Furthermore, wire breakage has frequently occurred.

Therefore, as a result of earnest research, the inventor has found that if the surface of the wire is roughened to a certain extent or more and the holding force of the loose abrasive grains on the wire surface is increased, the amount of the loose abrasive grains attached to the wire surface is increased. However, the inventors have found that the cutting efficiency and the cutting accuracy of the ingot can be improved, which suppresses the unevenness of the thickness of the wafer and the warp of the wafer, and also suppresses the occurrence of wire breakage, and completed the present invention.

[0005]

It is an object of the present invention to improve the cutting efficiency and the cutting accuracy of an object to be cut, and to suppress the occurrence of wire breakage, a method for cutting an object to be cut, a wire for cutting, and the wire. It is an object of the present invention to provide a manufacturing method of.

[0006]

According to a first aspect of the present invention, a wire bridged between a plurality of groove rollers is reciprocally run to supply an abrasive liquid containing loose abrasive grains while cutting an object to be cut. In the wire cutting method of the object to be cut by pressing the wire relatively to the wire and by the grinding action of the loose abrasive grains, and adjusting the surface roughness of the wire to a certain degree or more, It is a wire cutting method for an object to be cut by increasing the holding force of loose abrasive grains on the surface of the wire to cut the object.

The wire saw to be used may have a structure in which an object to be cut is moved and pressed against and brought into contact with the wire row to cut. On the contrary, the wire row may be moved to press and contact the object to be cut to cut it. Further, the lower surface of the object to be cut may be in contact with the upper portion of the wire row. Further, it may be of a type in which the upper surface of the object to be cut is pressed against the lower part of the wire row. The number of groove rollers arranged in the wire saw may be two, or three or more. Examples of the object to be cut by the wire saw include silicon single crystal, compound semiconductor single crystal, magnetic material, quartz, and ceramics. As the abrasive liquid used for cutting, for example, a liquid containing free abrasive grains such as SiC having an average particle diameter of 5 to 50 μm is adopted. The structure of the groove roller is not limited. For example, a lining material (urethane rubber) with a specified thickness on the outer peripheral surface of a cylindrical base metal
It is possible to employ a roller or the like in which the wire is engraved on the outer peripheral surface of the lining material.

As the wire, for example, carbon containing 0.7 to
A piano wire containing 0.8% can be adopted. The diameter of the wire is 50 to 200 μm when the object to be cut is a silicon single crystal, and 80 when it is a compound semiconductor single crystal.
~ 120 μm, 80-140 μm for magnetic material, 80-160 μm for quartz, 5 for ceramics
It is about 0 to 200 μm. Adjusting the roughness of the wire surface to a certain degree or more means adjusting the roughness so that the amount of loose abrasive grains attached to the wire surface increases, and the wire cutting efficiency and cutting accuracy of the workpiece are increased. .

The invention according to claim 2 is the method of cutting a wire according to claim 1, wherein the surface roughness of the wire is Ra 0.08 to 0.20 μm. Ra0.
If the thickness is less than 08 μm, it is difficult to control the dice during manufacturing, which causes a problem of cost increase. Also, Ra 0.20 μm
If it exceeds, the wire breakage rate will increase.

According to a third aspect of the present invention, the object to be cut is pressed by the object to be cut while being reciprocated between a plurality of groove rollers and is ground by the free abrasive grains in the supplied abrasive liquid. The wire for cutting is a wire having a surface roughness Ra of 0.08 to 0.20 μm.

The invention according to claim 4 is the wire according to claim 3, wherein the cross-sectional shape is a substantially perfect circle. The cross-sectional shape of the wire being substantially circular means that the wire is not a used wire having a flat cross-sectional shape but a new wire (unused).

[0012] According to a fifth aspect of the present invention, a steel wire rod is drawn through a drawing hole of a wire drawing die to perform a wire drawing step, and the steel wire rod after the wire drawing is austenitized and then transformed into a pearlite composition. In a wire manufacturing method comprising a patenting step of applying a patenting treatment to, a surface not subjected to plating treatment on the inner peripheral surface of the drawing hole of the wire drawing die, and by pulling out the wire from the drawing hole,
This is a wire manufacturing method in which the surface roughness of the wire is Ra 0.08 to 0.20 μm. A general-purpose type can be adopted as the wire manufacturing apparatus. However, the wire drawing die incorporated in the wire drawing apparatus is not plated with brass or the like which suppresses drawing resistance on the inner peripheral surface of the drawing hole.

The patenting means that the steel wire is austenitized in advance at a furnace temperature of about 900 ° C., and then about 5
It is a process of rapidly cooling to 50 to 600 ° C. and transforming it into a pearlite composition. The wire drawing step and the patenting step of the steel wire rod may be performed once or may be repeated a plurality of times. Further, the wire after the final patenting may be brass-plated on its surface. Brass plating is a plating method in which copper and zinc are sequentially plated on the surface of a wire, and then these copper and zinc are thermally diffused to form a brass alloy. Further, the wire after plating may be subjected to wet wire drawing. This wet wire drawing is to perform wire drawing while supplying lubricating oil to a wire drawing die and a steel wire rod.

According to the sixth aspect of the invention, a wire drawing step of drawing a steel wire rod through a drawing hole of a wire drawing die and a steel wire rod after the wire drawing process is transformed into a pearlite composition after austenitizing. In the wire manufacturing method, which comprises a patenting process for applying a patenting treatment, the inner peripheral surface of the drawing hole of the wire drawing die is a roughened surface, and the wire is drawn out from the drawing hole. Is a wire manufacturing method in which the roughness of the surface of Ra is 0.08 to 0.20 μm. As a processing method for finishing the inner peripheral surface of the drawing hole with a rough surface, for example, sand blast processing in which silica particles are mixed with high-pressure air and blown can be adopted. The roughened surface of the drawing hole may have its inner peripheral surface plated.

[0015]

According to the present invention, when the surface of the wire is roughened to a certain extent or more, the holding force of the loose abrasive grains on the wire surface is increased, and the amount of the loose abrasive grains attached to the wire surface is increased. Therefore, by cutting the object to be cut with the wire having such a large amount of loose abrasive particles attached (held), the cutting efficiency and the cutting accuracy can be improved. As a result, the unevenness of the wafer thickness and the warp of the wafer are suppressed, and the occurrence of wire breakage can also be suppressed.

In particular, according to the invention of claim 5, a high temperature steel wire is first drawn through the drawing hole of the wire drawing die and drawn. The inner peripheral surface of the drawing hole of this wire drawing die is not plated. Therefore, by repeatedly drawing the wire from the drawing hole, the inner peripheral surface of the drawing hole of the die is worn and broken. As a result, the surface roughness is Ra0.
A wire having a diameter of 08 to 0.20 μm can be easily manufactured. Then, the drawn steel wire rod is patented. That is, the steel wire is preheated to a furnace temperature of about 900
Austenitized at ℃, then about 550-600
Quench to ℃ and transform into a pearlite composition. The patenting process and the wire drawing process can be repeated a plurality of times as necessary. In that case, the diameter of the drawing hole is reduced so that the steel wire rod becomes thinner each time the wire drawing process is repeated.

According to the invention of claim 6, since the inner peripheral surface of the drawing hole is roughened, the surface is Ra 0.08 to 0.20 μm only by pulling out the steel wire from the drawing hole.
It is possible to obtain a wire having a rough surface of m. This makes it possible to easily manufacture a wire whose surface has a roughness of Ra 0.08 to 0.20 μm.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is an enlarged cross-sectional view of an essential part showing a cutting operation of an object to be cut by a wire cutting method for the object to be cut according to the conventional means. FIG. 1B is an enlarged cross-sectional view of an essential part showing a cutting operation of the object to be cut by the wire cutting method for the object to be cut according to the present invention. FIG. 2A is an enlarged schematic view showing an essential part of a wire saw to which the wire cutting method for an object to be cut according to an embodiment of the present invention is applied. FIG. 2B is a partially enlarged view of the groove roller incorporated in the wire saw according to the embodiment of the present invention. Figure 3
(A) is a graph which shows the surface roughness of the to-be-cut object used for the conventional wire cutting method of the to-be-cut object. FIG. 3B is a graph showing the surface roughness of the object to be cut used in the method for cutting the wire of the object to be cut according to the present invention.
FIG. 4 is a flow sheet showing a wire manufacturing method according to an embodiment of the present invention. FIG. 5A is an enlarged cross-sectional view of an essential part showing a wire drawing process of a steel wire rod in a wire manufacturing method according to an embodiment of the present invention. FIG. 5B is a partially enlarged sectional view of a die incorporated in the wire manufacturing apparatus according to the embodiment of the present invention.

In FIG. 2A, reference numeral 10 shows a wire saw according to an embodiment of the present invention. The wire saw 10 is a device for cutting an ingot (object to be cut) I for 8-inch wafer made of single crystal silicon pulled up by the CZ method into a large number of wafers. The wire saw 10 has three groove rollers 12A, 12B, 12C arranged in an inverted triangular shape when viewed from the front in the drawing. These groove rollers 12A, 12B, 12
Between C, one wire 11a is wound in parallel with each other at a constant pitch. As a result, the wire row 11 is exposed between the groove rollers 12A, 12B, 12C. The wire row 11 includes three groove rollers 12A, 1
It is reciprocated by a drive motor between 2B and 12C. The middle of the two groove rollers 12A and 12B arranged on the upper side is the ingot cutting position a of the wire row 11 for cutting the ingot I.

The ingot I is fixed to the lower surface of a lift table 19 for moving the ingot I up and down via a carbon bed 19a. Above both sides of the ingot cutting position a, for example, a pair of abrasive liquid supply units (not shown) for continuously supplying the abrasive liquid onto the wire array 11 are arranged. These groove rollers 12A, 12B, 12C have a cylindrical shape, and their outer peripheral surfaces are covered with lining materials 12a, 12b, 12c made of urethane rubber and having a predetermined thickness. Wire grooves 12d are formed on the outer peripheral surface of each of the lining materials 12a, 12b, 12c (FIG. 2).
(B)).

The wire 11a is a piano wire having a diameter of 150 μm, and the surface roughness is Ra 0.1283 μm (a contact-type surface roughness measuring instrument manufactured by Tokyo Seimitsu Co., Ltd., Surfcom).
1400D, Ra value is the same).
The wire 11a is led out from the bobbin 20 of the feeding device 13, is laid over these groove rollers 12A, 12B, 12C via a guide roller (not shown) on the supply side, and then is guided on the lead side. It is wound around the bobbin 21 of the winding device 15 via (not shown).
The rotating shafts of the bobbins 20 and 21 have drive motors 16 and 17, respectively.
Are respectively connected to the corresponding output shafts of. When the drive motors 16 and 17 are driven in synchronization, a pair of bearings 18
The bobbins 20 and 21 pivotally supported on the wire 11a rotate in the clockwise direction or the counterclockwise direction in FIG. 2A around the axis, and the wire 11a reciprocates.

Next, a method of cutting the ingot I with the wire saw 10 will be described. As shown in FIG. 2, in the wire saw 10, the bobbin 20 of the feeding device 13 is rotated by the drive motor 16 while supplying the abrasive liquid to the wire row 11 from the abrasive liquid supply unit, and the wire 11a is fed to the guide roller on the supply side. It supplies to groove roller 12A, 12B, 12C via. At the same time, the bobbin 21 of the winding device 15 is rotated by the drive motor 17, and the groove rollers 12A,
The wire 11a is wound up via the guide rollers 12B and 12C and the lead-out side. At that time, each bobbin 2 at a constant cycle
The rotation directions of 0 and 21 are changed, and the wire 11a is reciprocated. As a result, the two groove rollers 12A, 12B
Rotates, and both guide rollers also rotate. At this time, the groove roller 12C is rotated by a rotation motor (not shown) to assist the wire train 11 in the reciprocating movement. On the other hand, while the wire train 11 is traveling back and forth, the ingot I is fed from above from the wire train 1.
Press to 1. As a result, the ingot I is cut into a large number of wafers. That is, when the wire array 11 travels back and forth, loose abrasive grains in the polishing liquid are removed from the wire 1 of the wire array 11.
1a rubs against the bottom of the cutting groove, the bottom is gradually scraped off by the grinding action, and finally cut into a large number of wafers.

As shown in the graph of FIG. 3A, the conventional wire 100 had a surface roughness as small as Ra 0.0128 μm and had a smooth surface. Therefore, the loose abrasive grains b are unlikely to adhere to the surface of the wire 100 during the cutting of the ingot (FIG. 1A), and the cutting efficiency and the cutting accuracy of the ingot I are reduced. On the other hand, as shown in the graph of FIG. 3 (b), the wire 11 a of the example has a surface roughness Ra of 0.1283 μm, which is relatively large, and has a rough surface finish. As a result, the holding force of the loose abrasive grains b on the surface of the wire 11a is increased when the ingot is cut,
As a result, the loose abrasive grains b easily adhere to the surface of the wire 11a (FIG. 1 (b)). As a result, the cutting efficiency and cutting accuracy of the ingot I are improved, and it is possible to suppress unevenness in thickness and warpage of the silicon wafer. Moreover, it is possible to suppress the occurrence of disconnection of the wire 11a. Actually, the cutting test of the ingot I was performed using the conventional wire 100 and the wire 11a of the embodiment. as a result,
The wire 11a of this example has improved the cutting efficiency by about 15%, the wafer thickness unevenness by about 15%, and the wafer warpage by about 15% as compared with the conventional product.

Now, a method of manufacturing the wire 11a of this embodiment will be described with reference to the flow sheet of FIG. First, a steel wire having a diameter of 5 to 6 mm that has been adjusted and cooled after hot rolling is prepared (S401), and this is subjected to primary wire drawing by a cold drawing device to a diameter of 3 to 4 mm (S402).
Hereinafter, this cold drawing apparatus will be described in detail with reference to FIG. In FIG. 5, reference numeral 30 is a cold drawing device, and this cold drawing device 30 is provided on the drawing side of a steel wire rod with a wire drawing die 3
1 is fixed. The wire drawing die 31 is formed with a drawing hole 31a whose cross-sectional area is gradually reduced from the inlet of the steel wire rod toward the outlet thereof. At the tip (downstream) of the wire drawing die 31, the tip portion of the steel wire material is clamped to draw out a hole 31a.
A pair of upper and lower pulling rollers 32 for pulling the steel wire rod from the
32 are provided. The steel wire rod can be pulled out from the pull-out hole 31a by rotating both the pull-out rollers 32, 32 with the front end portion of the steel wire rod being sandwiched.

Next, the steel wire rod after the primary wire drawing is subjected to patenting treatment (S403). Specifically, the steel wire rod is austenitized at a furnace temperature of about 900 ° C in advance,
Then, it is rapidly cooled to about 550 to 600 ° C. and transformed into a pearlite composition. Subsequently, the patented steel wire rod is subjected to secondary wire drawing by the cold drawing device 30 to obtain a steel wire rod having a diameter of 1 to 2 mm (S404). Then 2
The final patenting treatment is applied to the steel wire rod subjected to the secondary wire drawing (S405). Then, brass plating is applied to the surface of the finally patented steel wire rod (S4
06). That is, the surface of a steel wire rod is sequentially plated with copper and zinc, and then these are thermally diffused to obtain a brass alloy. Next, final wet wire drawing is performed on the brass-plated steel wire rod (S407). Specifically, wire drawing is performed while spraying a lubricating oil on a wire drawing die, a steel wire material and the like. As the wire drawing die 31 used here, one in which the inner peripheral surface of the drawing hole 31a is roughened by sandblasting is employed (FIG. 5 (b)). As a result, the surface of the wire 11a can be finished to a rough surface of Ra 0.08 to 0.20 μm simply by pulling out the steel wire rod from the pulling hole 31a. As a result, this Ra0.08
Wires with a surface of ˜0.20 μm can be easily manufactured.

[0026]

According to the present invention, by roughening the surface of the wire to a certain degree or more, the amount of loose abrasive grains attached to the wire surface (holding force) increases, and the cutting performance of the object to be cut is improved. The cutting efficiency and cutting accuracy can be improved. As a result, uneven thickness of the wafer and warp of the wafer are suppressed, and wire breakage can also be suppressed.

In particular, according to the invention of claim 5, the steel wire is drawn by using a wire drawing die which is not plated on the inner peripheral surface of the drawing hole, so that the surface roughness is Ra0.00.
A wire of 8 to 0.20 μm can be easily manufactured.

Further, according to the invention of claim 6, the steel wire is drawn out through the drawing hole whose inner peripheral surface is roughened, so that a wire having a surface roughness Ra of 0.08 to 0.20 μm can be manufactured well. can do.

[Brief description of drawings]

FIG. 1A is an enlarged cross-sectional view of an essential part showing a work of cutting an object to be cut by a wire cutting method of the object to be cut according to a conventional means. FIG. 3B is an enlarged sectional view of an essential part showing a cutting operation of the object to be cut by the wire cutting method for the object to be cut according to the present invention.

FIG. 2A is an enlarged schematic view showing a main part of a wire saw to which a method of cutting a wire of an object to be cut according to an embodiment of the present invention is applied. FIG. 6B is a partially enlarged view of the groove roller incorporated in the wire saw according to the embodiment of the present invention.

FIG. 3A is a graph showing the surface roughness of the object to be cut used in the wire cutting method for the object to be cut according to the conventional means. (B) is a graph which shows the surface roughness of the to-be-cut object used for the wire cutting method of the to-be-cut object concerning this invention.

FIG. 4 is a flow sheet showing a wire manufacturing method according to an embodiment of the present invention.

FIG. 5 (a) is an enlarged sectional view of an essential part showing a wire drawing step of a steel wire rod in a wire manufacturing method according to an embodiment of the present invention. (B) is a partial enlarged sectional view of a die incorporated in a wire manufacturing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

10 wire saw, 11a wire, 12A, 12B, 12C groove rollers, 12d wire groove, 31 wire drawing die, 31a Extraction hole, I ingot (cut object), b Free abrasive grains.

Claims (6)

[Claims] 1. A wire suspended between a plurality of groove rollers is made to reciprocate, and an object to be cut is relatively pressed against the wire while supplying a polishing liquid containing free abrasive particles, whereby the free abrasive particles are removed. In the wire cutting method of the cutting object for cutting the cutting object by the grinding action of, by adjusting the surface roughness of the wire to a certain degree or more,
A wire cutting method for an object to be cut, which increases the holding force of loose abrasive grains on the surface of the wire to wire the object to be cut. 2. The surface roughness of the wire is Ra0.00.
The wire cutting method for an object to be cut according to claim 1, having a thickness of 8 to 0.20 μm. 3. A wire for cutting an object to be cut by the grinding action of loose abrasive grains in a supplied abrasive liquid, which is pressed against the object to be cut while reciprocating between a plurality of groove rollers. A wire having a surface roughness Ra of 0.08 to 0.20 μm. 4. The wire according to claim 3, wherein the cross-sectional shape is a substantially perfect circle. 5. A patenting process for drawing a steel wire rod through a drawing hole of a wire drawing die, and a patenting process for transforming the steel wire rod into an pearlite composition after austenitizing the drawn steel wire rod. In the wire manufacturing method including a coating step, the inner peripheral surface of the drawing hole of the wire drawing die is a surface not subjected to plating treatment, and the wire is pulled out from the drawing hole to obtain a surface roughness of the wire. Ra 0.08 to 0.20
A method of manufacturing a wire having a size of μm. 6. A patenting process for drawing a steel wire rod through a drawing hole of a wire drawing die, and a patenting process for transforming the steel wire rod into a pearlite composition after austenitizing the drawn steel wire rod. In a wire manufacturing method including a wire drawing step, the inner peripheral surface of the drawing hole of the wire drawing die is a roughened surface, and the wire is drawn out from the drawing hole to obtain a surface roughness Ra0. The wire manufacturing method was set to 0.08 to 0.20 μm.