JP2018065205A - Saw wire and slicing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a saw wire capable of obtaining a cut surface capable of shortening a required time for etching in comparison with hitherto, even when slicing an ingot of polycrystalline silicon by a fixed abrasive grain method; and to provide a slicing method.SOLUTION: A saw wire 10 includes a core wire 12, a resin 14 for coating the outer peripheral surface of the core wire 12, and a particle group 16 fixed to the core wire 12 through the resin 14. The particle group 16 contains abrasive grains 18, and hard particles 20 having a smaller particle size than the abrasive grains 18. The abrasive grains 18 are fixed unitarily, and the hard particles 20 are fixed in the state of a coupling body 22 formed by coupling a plurality of hard particles 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a saw wire and a slice processing method, and more particularly to a technique for processing a workpiece into a thin plate using a multi-wire saw.

  While renewable energy is attracting attention, crystalline silicon solar cells are widely used as solar cell modules (hereinafter simply referred to as “solar cells”) used in power generation systems using sunlight.

  A crystalline silicon solar cell incorporates a cell that is a photoelectric conversion element that converts absorbed light energy into electric power. A silicon wafer is used to form this cell. A silicon wafer is obtained by cutting silicon, which is a semiconductor material, from a single crystal or polycrystal ingot and processing it into a thin plate. A multi-wire saw is used for the processing.

  A multi-wire saw is a device that slices a workpiece by pressing the workpiece against the traveling saw wire while traveling the saw wire wound around a plurality of grooved rollers having parallel rotation axes. Between adjacent grooved rollers, a wire row in which a part of the saw wire is stretched in parallel at an equal pitch is formed. According to the multi-wire saw, since slicing is performed at the wire row portion, a large number of silicon wafers can be cut out at a time from the ingot to be processed.

  Slicing using the multi-wire saw is roughly classified into a “free abrasive grain method” and a “fixed abrasive grain method”. The free abrasive grain system runs the saw wire while supplying slurry containing abrasive grains, while the fixed abrasive grain system runs the saw wire with the abrasive grains fixed to the outer peripheral surface while supplying the coolant. In recent years, from the viewpoint of environmental considerations, machinability, and the like, a fixed abrasive system that can use a water-soluble coolant and has a large amount of cutting per unit time has become mainstream. Patent Document 1 also discloses a technique of using a fixed abrasive method and a free abrasive method together in order to further improve machinability.

  By the way, on the surface of the silicon wafer, a minute uneven structure (hereinafter referred to as “texture structure”) having a pyramid shape is formed for the purpose of confining light. The texture structure is generally formed by etching the wafer surface. In the case of a polycrystalline silicon wafer, since the crystal orientation on its surface is irregular, acid etching (isotropic etching) is usually performed.

  However, the surface (cut surface) of the polycrystalline silicon wafer sliced by the fixed abrasive method occupies most of the ductile fracture region (hereinafter referred to as “ductile region”). This ductile region is smooth and has a high light reflectance, and has a property that it is difficult to form a textured recess (hereinafter referred to as “dimple”). For this reason, when slicing by the fixed abrasive method, the time required for etching becomes long in the process of forming the texture structure on the wafer surface.

  Thus, although the fixed abrasive method with excellent machinability has the advantage of shortening the processing time for slicing the ingot, from the viewpoint of cell formation, there is also a problem that the time required for etching on the wafer surface becomes long. is there. In order to overcome this difficulty, it is conceivable to perform etching after performing a surface treatment for roughening the wafer surface. However, the required man-hours increase, which is not preferable in terms of cell production efficiency.

JP 2013-52463 A

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a saw wire and a slicing method that can obtain a cut surface that can reduce the time required for etching even when a polycrystalline silicon ingot is sliced by a fixed abrasive method. The purpose is to provide.

  To achieve the above object, a saw wire of the present invention comprises a core wire, a resin covering an outer peripheral surface of the core wire, and a particle group fixed to the core wire via the resin, and the particle group includes an abrasive. Characterized in that the abrasive grains are fixed as a single body, and the hard particles are fixed in a combined state in which a plurality of the hard particles are combined. To do.

  The bonding force of the bonded body to the core wire is smaller than the bonding force of the abrasive grains to the core wire.

  A part of the combined body is embedded in the resin.

  The protrusion height of the bonded body from the resin surface is lower than the protrusion height of the abrasive grains from the resin surface.

  The quantity ratio of the abrasive grains and the bonded body per unit length of the core wire is 1: 1 to 1: 2.

  The hard particles include hexagonal boron nitride.

  The average particle diameter of the hard particles per unit length of the core wire is 1/3 or less of the average particle diameter of the abrasive grains, and 1 / of the maximum protruding height of the abrasive grains from the resin surface. It is 2 or less.

  Further, the slicing method of the present invention is to slice a polycrystalline silicon ingot against the traveling saw wire while traveling a saw wire having a plurality of abrasive grains fixed to the outer peripheral surface of the core wire through a resin. A slicing method for processing an ingot into a wafer, wherein a combination of a plurality of hard particles having a particle diameter smaller than the abrasive grains and a cooling liquid are interposed between the core wire and the ingot; Separating the intervened bonded body into a single state of the hard particles between a core wire and the ingot.

  The combined body is fixed to the core wire via the resin, and the combined body and the cooling liquid are interposed by bringing the coolant into contact with the saw wire immediately before the saw wire comes into contact with the ingot. It is characterized by making it.

  Alternatively, the conjugate is dispersed as a dispersoid in a suspension using the cooling liquid as a dispersion medium, and the suspension is brought into contact with the saw wire immediately before the saw wire comes into contact with the ingot. The combined body and the cooling liquid are interposed.

  According to the saw wire and the slicing method according to the present invention, since the polycrystalline silicon ingot is cut with the abrasive grains fixed to the core wire via the resin, the cutting ability equivalent to that of the conventional fixed abrasive grain system is exhibited. Further, when the bonded body fixed to the core wire through the resin is interposed between the core wire and the ingot, it is separated into a single hard particle state by the action of an external force applied by the contact between the traveling saw wire and the ingot. . Then, each of the separated hard particles collides with the ingot, and a very fine crack that becomes a starting point for forming dimples when etching is formed at the collided portion. As a result, even if the ingot of polycrystalline silicon is sliced by the fixed abrasive method, a cut surface that can shorten the time required for etching can be obtained as compared with the prior art.

It is a perspective view which shows schematic structure of a multi-wire saw. It is a side view which shows schematic structure of a multi-wire saw. (A) is a schematic perspective view which shows a part of saw wire which concerns on embodiment, (b) is an enlarged view of the longitudinal cross-section in the part enclosed with the broken line of the figure (a). (A) is a bottom view of the saw wire slicing a workpiece, and (b) is a transverse cross-sectional view thereof. It is the schematic which shows the behavior of the conjugate | bonded_body when slicing a workpiece.

  Hereinafter, for each embodiment of the saw wire and the slicing method according to the present invention, a drawing of cutting a polycrystalline silicon wafer (hereinafter simply referred to as “wafer”) from an ingot using a multi-wire saw is taken as an example. Will be described with reference to FIG.

<Embodiment 1>
As shown in FIGS. 1 and 2, the multi-wire saw 100 used in this example includes a plurality of (three in this example) grooved rollers 102A, 102B, and 102C having parallel rotation axes. A large number of guide grooves (not shown) are provided at equal pitches on the outer peripheral surfaces of the grooved rollers 102A, 102B, and 102C. The multi-wire saw 100 also includes a supply reel 104F and a take-up reel 104T.

  The saw wire 10 according to the embodiment is wound and accommodated on the supply reel 104F. The saw wire 10 unwound from the supply reel 104F is wound around the guide grooves of the grooved rollers 102A, 102B, and 102C in order, and is repeatedly bridged. Thereby, between adjacent grooved rollers 102A, 102B, 102C, a wire row 10L is formed in which saw wires 10 are stretched in parallel at an equal pitch along the outer periphery of each roller. The saw wire 10 unwound from the grooved roller 102B is wound around the take-up reel 104T and is wound and accommodated.

  Each of the grooved roller 102A, the supply reel 104F, and the take-up reel 104T is rotationally driven by power of a corresponding motor (all not shown) or the like, and the saw wire 10 travels along with the rotational drive. On the other hand, each of the grooved rollers 102 </ b> B and 102 </ b> C is driven to rotate by a frictional force generated between the traveling rollers 10 </ b> B and 102 </ b> C. The traveling direction of the saw wire 10 is switched in the traveling path from the supply reel 104F to the take-up reel 104T by rotating the grooved roller 102A or the like forward and backward.

  The multi-wire saw 100 further includes a pair of liquid supply nozzles 106A and 106B having a supply port (not shown) for coolant that is a coolant. Each of the liquid supply nozzles 106A and 106B is provided above the central portion of the wire row 10L stretched between the grooved roller 102A and the grooved roller 102B with a space in the horizontal direction. In a space between the liquid supply nozzle 106A and the liquid supply nozzle 106B, a polycrystalline silicon ingot 108 serving as a workpiece is set. The ingot 108 is fixed to a movable base 110 that moves up and down relatively with respect to the wire row 10L immediately below the ingot 108 via a discard plate (not shown).

  The saw wire 10 according to the embodiment is a flexible long wire cutting tool (cutting tool) that is used by being mounted on the multi-wire saw 100 described above. As shown in FIGS. 3 and 4, the saw wire 10 includes a core wire 12 having a circular cross section. The outer peripheral surface of the core wire 12 is covered with a resin 14. The particle group 16 is fixed to the core wire 12 through the resin 14.

  The core wire 12 is made of a high-tensile steel wire material such as a high carbon steel wire (for example, a piano wire) or a stainless steel wire having a wire diameter of about 0.05 mm to 0.3 mm. In this example, an axial length of about 100 km along the axis C of the core wire 12 is used. However, as long as the multi-wire saw 100 described above can be used, the axial length is It may be shorter or longer than 100 km.

  The resin 14 is an adhesive layer formed by curing an adhesive mainly composed of a resin. Specifically, the constituent components of the adhesive include a phenol resin as a main component and a silane coupling agent added thereto. The resin 14 may contain a filler (not shown) for reinforcing the strength.

  The particle group 16 includes a plurality of abrasive grains 18. The abrasive grains 18 are superabrasive grains such as diamond and cubic boron nitride (c-BN). Each of the abrasive grains 18 is fixed to the core wire 12 in a single state. All of the fixed abrasive grains 18 are partially embedded in the resin 14, and the other portions protrude from the surface of the resin 14. The abrasive grains 18 may be general abrasive grains such as alumina and silicon carbide, or a mixture of super abrasive grains and general abrasive grains.

  The protrusion height H1 of each abrasive grain 18 from the surface of the resin 14 (FIG. 3B) is 3 μm to 10 μm, preferably 4 μm to 6 μm, most preferably, per unit length in the axial direction of the core wire 12. It is around 5 μm. If the average protrusion height per unit length of the abrasive grains 18 is smaller than 3 μm, the cutting amount per unit time is reduced, and the machinability may be insufficient. On the other hand, when the average protrusion height is larger than 10 μm, kerf loss increases. In this example, in consideration of the protrusion height H1, diamond abrasive grains having an average particle diameter in the range of 8 μm to 12 μm are used as the abrasive grains 18.

  The particle group 16 also includes a plurality of hard particles 20. The hard particles 20 are hexagonal boron nitride (h-BN) fine particles. Here, “hard” means that the hardness is equal to or higher than that of an ingot of polycrystalline silicon. Each of the hard particles 20 has a particle size smaller than that of the abrasive grains 18 and is fixed to the core wire 12 in a state where several hard particles 20 are bonded to form one bonded body 22. The hard particles 20 constituting the bonded body 22 are bonded to each other through a silane coupling agent. All of the bonded bodies 22 that are fixed are embedded in the resin 14, and the other parts protrude from the surface of the resin 14. The protrusion height H2 (FIG. 3B) from the surface of the resin 14 of each of the bonded bodies 22 is slightly lower than the protrusion height H1 of the abrasive grains 18.

  The average particle size per unit length of the hard particles 20 is 1/3 or less of the average particle size of the abrasive grains 18, and the protrusion height H1 of each abrasive grain 18 per unit length. The size is ½ or less of the maximum height (the maximum protrusion height of the abrasive grains 18). When the average particle diameter of the hard particles 20 is larger than this, the hard particles 20 function in the same manner as the abrasive grains 18 and not only a desired cut surface is obtained, but also the apparent particles of the bonded body 22. The diameter also increases and it becomes easy to detach from the core wire 12 wastefully.

  As described above, a plurality of abrasive grains 18 and a plurality of combined bodies 22 are mixed in the particle group 16 fixed to the core wire 12. The distribution of the abrasive grains 18 and the bonded body 22 in the core wire 12 is as follows. That is, when the number of abrasive grains 18 per unit length is “n” and the number of bonded bodies 22 is “m”, the quantity ratio of the abrasive grains 18 and bonded bodies 22 per unit length (n: m ) Is 1: 1 to 1: 2. When the average grain size of the abrasive grains 18 is “R”, the center-to-center distance L1 between adjacent abrasive grains 18 (FIG. 3B) is about 2.5 to 5 times the average grain size R. Size (2.5R ≦ L1 ≦ 5R). Furthermore, the center-to-center distance L2 between the adjacent abrasive grains 18 and the bonded body 22 (FIG. 3B) is approximately the same (1 times) to 2.5 times as large as the average particle diameter R (R ≦ L2 ≦ 2.5R).

  Further, the abrasive grains 18 and the bonded body 22 have different adhesion forces to the core wire 12. Specifically, the bonded body 22 has a smaller fixing force than the abrasive grains 18. The abrasive grains 18 are firmly fixed so that even if the saw wire 10 travels in a state where the ingot 108 is pressed, the abrasive grains 18 are not easily detached from the core wire 12. On the other hand, the joined body 22 is fixed with a strength enough to separate from the core wire 12 by the action of an external force applied by contact between the traveling saw wire 10 and the ingot 108. However, the combined body 22 is brought into contact with the grooved rollers 102A, 102B, and 102C as the saw wire 10 travels, between the portions of the saw wire 10 wound and accommodated on the supply reel 104F and the take-up reel 104T. The applied external force has a fixing force that does not easily detach from the core wire 12.

  When the saw wire 10 is mounted on the multi-wire saw 100 and used, the distribution of the particle group 16 in the core wire 12 and the fixing force of each of the abrasive grains 18 and the bonded body 22 are designed as described above. 18, It becomes possible to make the coupling body 22 (hard particles 20) function as described later. In addition, by designing the fixing force of the bonded body 22 with the above-mentioned strength, the bonded body 22 can be removed from the core wire 12 as much as possible to the part to be processed (the portion where the saw wire 10 contacts the ingot 108). Can be brought in.

  Next, the slice processing method according to the embodiment will be described together with the operation of the multi-wire saw 100 described above.

  First, as shown in FIG. 1, the ingot 108 is fixed to the movable base 110 and set in a space between the liquid supply nozzle 106A and the liquid supply nozzle 106B (step S0).

  Subsequently, the grooved roller 102A, the supply reel 104F, and the take-up reel 104T are driven to rotate, and the saw wire 10 is caused to travel in the first direction from the supply reel 104F to the take-up reel 104T. In parallel with this, while the coolant is supplied from the liquid supply nozzle 106A on the supply reel 104F side to the wire row 10L immediately below, the movable base 110 is lowered, and the ingot 108 is attached to the wire row 10L to which the coolant adheres. Press the bottom surface of. In this way, the abrasive grain group 16 (the abrasive grains 18 and the bonded body 22) and the coolant are interposed between the core wire 12 and the ingot 108 (step S1).

  In a state where the ingot 108 is pressed against the wire row 10L, the saw wire 10 is continuously run. As a result, the ingot 108 is cut with the abrasive grains 18 fixed to the surface of the saw wire 10 running through the wire row 10L. At the same time, the joined body 22 interposed by the above step S1 is separated from the core wire 12 between the core wire 12 and the ingot 108, and further, the joined body 22 is separated into the hard particles 20 alone (step S2).

  The steps S1 and S2 are continued as they are, for example, until the saw wire 10 having a length of about several kilometers travels in the first direction. In the meantime, the saw wire 10 continues to run while being in contact with the ingot 108 in the wire row 10L. As a result, as shown in FIGS. 2 and 4, the same number of cutting grooves 108 </ b> R as the saw wires 10 traveling in the wire row 10 </ b> L are formed on the lower surface of the ingot 108.

  When the length of the saw wire 10 traveling in the first direction reaches about several km, the traveling direction of the saw wire 10 is reversed. That is, the grooved roller 102A, the supply reel 104F, and the take-up reel 104T are driven in reverse rotation, and the saw wire 10 is caused to travel backward in the second direction from the take-up reel 104T to the supply reel 104F. In parallel with this, the coolant is supplied from the liquid supply nozzle 106B on the take-up reel 104T side to the wire row 10L immediately below, and the ingot 108 is pressed against the wire row 10L to which the coolant adheres. In this manner, the abrasive grain group 16 (abrasive grains 18 and the bonded body 22) and the coolant are interposed between the core wire 12 and the ingot 108 in the same manner as in Step S1 (Step S3).

  Similarly to step S2, the saw wire 10 is continuously run in a state where the ingot 108 is pressed against the wire row 10L. As a result, the ingot 108 is cut with the abrasive grains 18 fixed to the surface of the saw wire 10 running through the wire row 10L, and the joined body 22 interposed between the core wire 12 and the ingot 108 in step S3 is the core wire. 12 and further, the bonded body 22 is separated into the hard particles 20 alone (step S4).

  Then, the steps S1 and S2 and the steps S3 and S4 are alternately repeated while shortening the length of the saw wire 10 that travels in the second direction as compared to when traveling in the first direction. Thereby, the ingot 108 is sliced and cut out as a thin wafer. If the multi-wire saw 100 that slices the ingot 108 at the wire row 10L is used, a large number of wafers can be cut out at a time.

  Here, the behavior of the combined body 22 in the steps S1 and S2 will be described in detail with reference to FIG. The steps S3 and S4 are substantially the same as the steps S1 and S2 except that the traveling direction of the saw wire 10 is reversed. Therefore, the description of the behavior of the combined body 22 in steps S3 and S4 is omitted.

  As described above, in step S1, as shown in FIG. 5A, the coupling body 22 and the coolant are interposed between the core wire 12 and the ingot 108. During the slicing process, the saw wire 10 travels at a speed of, for example, about 1000 m / min. Therefore, a corresponding kinetic energy is given to the coupling body 22 that moves at high speed together with the saw wire 10.

  In step S2, as shown in FIG. 5 (b), the combined body 22 is detached from the core wire 12 due to the external force applied by the contact between the traveling saw wire 10 and the ingot 108 and the action of torsional force, and the separated combined body 22 is separated. Is then separated into a single hard particle 20 state. In the meantime, since the saw wire 10 continues to run at a high speed, the separated single hard particles 20 collide with the cut surface 108S of the ingot 108 cut by the abrasive grains 18 with corresponding kinetic energy.

  As shown in FIG. 5C, very fine cracks 108C are formed on the cut surface 108S where the hard particles 20 collide. The crack 108C is continuously formed along the cut surface 108S while the steps S1 and S2 are continued. As a result, a large number of cracks 108C are formed on the cut surface 108S in a substantially uniformly dispersed state.

  In addition, a hole 14P that is recessed toward the core wire 12 is formed in the resin 14 portion to which the detached bonded body 22 is fixed. By forming the hole portion 14P, the following advantages are obtained. That is, since the hole 14P functions as a chip pocket, clogging due to cutting waste (not shown) of the ingot 108 cut by the abrasive grains 18 is less likely to occur. Moreover, the hole 14P also functions as a temporary accommodating portion for the coolant, and the coolant is efficiently carried to the workpiece. Furthermore, the apparent protrusion height of the abrasive grains 18 is increased by the depth of the hole 14P. As a result, the machinability of the saw wire 10 is improved as compared with the case where there is no hole 14P.

  On the surface (cut surface 108S) of the wafer obtained by the slicing method described above, a striped pattern in which strip-like ductile regions having slightly different light reflectivity are alternately arranged appears. This striped pattern includes a first region having a lower light reflectance than the regions on both sides thereof, and a second region having a higher light reflectance than the first region. However, many cracks 108 </ b> C are formed in the first region and the second region as described above. Each of these cracks 108C becomes a starting point where dimples are formed by etching. That is, it can be said that the cut surface 108S composed of the first region and the second region is already in a state in which dimples are easily formed at this point without requiring any surface treatment before etching. For this reason, the ductile region of the cut surface 108S requires a shorter etching time compared to the conventional case.

  As described above, according to the saw wire 10 and the slicing method according to the embodiment, the ingot 108 is cut with the abrasive grains 18 fixed to the core wire 12 via the resin 14, and therefore, equivalent to the conventional fixed abrasive system. Demonstrate cutting performance. In addition, the joined body 22 fixed to the core wire 12 via the resin 14 is hardened by the action of external force applied by contact between the traveling saw wire 10 and the ingot 108 when interposed between the ingot 108 and the core wire 12. The particles 20 are separated into a single state. Then, each of the separated hard particles 20 collides with the ingot 108 and forms a very fine crack 108 </ b> C that becomes a starting point where dimples are formed when etching is performed. Thereby, compared with the conventional sliced by the fixed abrasive method, the cut surface 108S which can shorten the time required for etching comes to be obtained.

  The saw wire 10 and the slicing method according to the embodiment of the present invention have been described above. However, the present invention is not limited to the above-described form, and may be implemented in the following form, for example. Absent. In the following description, the same reference numerals are given to configurations that are basically the same as those in the above embodiment. Further, the description will focus on the parts that are different from the above embodiment, and the description regarding matters common to the above embodiment will be simply referred to or omitted as appropriate.

<Embodiment 2>
In the first embodiment, the saw wire 10 having the bonded body 22 fixed to the core wire 12 is attached to the multi-wire saw 100 and the ingot 108 is sliced. However, all the bonded bodies 22 are not necessarily fixed to the saw wire 10. . For example, a suspension in which the coolant that is the coolant is a dispersion medium and the combined body 22 is a dispersoid may be prepared, and this suspension may be supplied from the supply nozzles 106A and 106B to the wire row 10L. .

  In this case, the coolant is preferably a liquid having a relatively high viscosity. By using such a coolant, after supplying the suspension to the saw wire 10, the joined body 22 remains attached to the saw wire 10, and the processed portion of the ingot 108 (between the ingot 108 and the core wire 12). ).

  The suspension in which the combined body 22 is dispersed contacts the saw wire 10 immediately before the saw wire 10 contacts the ingot 108, and travels to a position where the saw wire 10 to which the suspension adheres contacts the ingot 108. The coupling body 22 and the coolant are interposed between 108 and the core wire 12. In this state, even when the saw wire 10 travels at a high speed, the bonded body 22 dispersed in the suspension exhibits the same behavior as the behavior in steps S1 and S2 (FIG. 5). Therefore, similarly to the first embodiment, the cut surface 108S can be obtained that exhibits the same machinability as the conventional fixed abrasive method and can reduce the etching time as compared with the conventional sliced method using the fixed abrasive method. It is done.

  When supplying the suspension in which the bonded body 22 is dispersed to the wire row 10L, a known saw wire (not shown) in which only the abrasive grains 18 are fixed to the core wire 12 is used for the multi-wire saw 100 instead of the saw wire 10. Of course, the ingot 108 may be sliced by mounting. In short, it is sufficient that at least one of the saw wire and the coolant includes the bonded body 22.

  Further, in the second embodiment, the saw wire 10 is not limited to the method of slicing the ingot 108 while alternately switching the traveling direction of the saw wire 10 between the first direction and the second direction, and the saw wire 10 is moved from the supply reel 104F to the take-up reel 104T. A method of slicing the ingot 108 by traveling only in the first direction may be adopted. In this case, if the roles of the take-up reel 104T and the supply reel 104F are changed, the ingot 108 can be sliced by running the saw wire 10 only in the second direction.

<Modification 1>
In the first and second embodiments, hexagonal boron nitride (h-BN) fine particles are used as the hard particles 20 constituting the bonded body 22. However, for example, super hard fine particles such as fine ceramics may be used. . Also, diamond, which is the same material as the abrasive grain 18, superabrasive grains such as cubic boron nitride (c-BN), general abrasive grains such as alumina and silicon carbide, or a mixture of superabrasive grains and general abrasive grains. It is also possible to employ one having a particle size smaller than that of the abrasive grains 18.

  In addition, even if it forms a conjugate | bonded_body with any particle | grains, it is desirable to couple | bond together particle | grains through a silane coupling agent. This is because the silane coupling agent is a binder containing silicon atoms (Si), and thus can be removed by etching even if it adheres as a residue to the cut surface of the sliced wafer. However, for example, a bonded body may be formed by bonding particles using a phenol resin or the like as a binder.

<Modification 2>
In the said Embodiment 1, 2, although the saw wire 10 was the monofilament structure using the core wire 12 comprised with the single high-tensile steel wire, the core wire by which the several high-tensile steel wire was bundled and twisted together was used. You may apply to the used multi-filament structure saw wire.

<Modification 3>
In the first and second embodiments, the multi-wire saw 100 including the three grooved rollers 102A, 102B, and 102C is used. However, the number of grooved rollers may be two, or four or more. Absent. In short, it is sufficient to use a multi-wire saw configured to form a wire array for slicing an ingot when a saw wire is mounted.

  The present invention can be implemented in a mode in which various improvements, modifications, or variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention. Moreover, you may implement with the form which substituted any invention specific matter to the other technique within the range which the same effect | action or effect produces.

DESCRIPTION OF SYMBOLS 10 Saw wire 12 Core wire 14 Resin 16 Particle group 18 Abrasive grain 20 Hard particle 22 Combined body

Claims (10)

Core wire,
A resin covering the outer peripheral surface of the core wire;
A group of particles fixed to the core wire via the resin;
With
The particle group includes abrasive grains and hard particles having a smaller particle diameter than the abrasive grains,
The saw wire is fixed as a single body, and the hard particles are fixed in a combined state in which a plurality of the hard particles are combined.   The saw wire according to claim 1, wherein the bonding force of the bonded body to the core wire is smaller than the bonding force of the abrasive grains to the core wire.   The saw wire according to claim 1 or 2, wherein a part of the combined body is embedded in the resin.   The saw wire according to any one of claims 1 to 3, wherein a protrusion height of the bonded body from the resin surface is lower than a protrusion height of the abrasive grains from the resin surface.   The saw wire according to any one of claims 1 to 4, wherein a quantity ratio of the abrasive grains per unit length of the core wire to the combined body is 1: 1 to 1: 2. .   The saw wire according to any one of claims 1 to 5, wherein the hard particles include hexagonal boron nitride.   The average particle diameter of the hard particles per unit length of the core wire is 1/3 or less of the average particle diameter of the abrasive grains, and 1 / of the maximum protruding height of the abrasive grains from the resin surface. The saw wire according to any one of claims 1 to 6, wherein the saw wire is 2 or less. A slice processing method in which a saw wire, in which a plurality of abrasive grains are fixed to the outer peripheral surface of the core wire through a resin, is run while slicing the ingot of polycrystalline silicon against the running saw wire and processing the ingot into a wafer. There,
Interposing a bonded body in which a plurality of hard particles having a particle diameter smaller than the abrasive grains and a cooling liquid are interposed between the core wire and the ingot;
Separating the intervened bonded body into a state of the hard particles alone between the core wire and the ingot;
A slice processing method comprising: The bonded body is fixed to the core wire via the resin,
9. The slicing method according to claim 8, wherein the combined body and the cooling liquid are interposed by bringing the cooling liquid into contact with the saw wire immediately before the saw wire comes into contact with the ingot. The conjugate is dispersed as a dispersoid in a suspension using the cooling liquid as a dispersion medium,
The slicing method according to claim 8, wherein the combined body and the cooling liquid are interposed by bringing the suspension into contact with the saw wire immediately before the saw wire comes into contact with the ingot.

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