Saw wire and cutting device

Abstract

To provide a saw wire capable of reducing loss of an object to be cut. [Solution] The saw wire 10 comprises a metal wire made of pure tungsten, the surface roughness Ra of the metal wire is greater than 0.05 μm and not greater than 0.15 μm, the elastic modulus of the metal wire is 350 GPa or more and 450 GPa or less, the tensile strength of the metal wire is 3500 MPa or more and 6000 MPa or less, and the wire diameter of the metal wire is 10 μm or more and 60 μm or less.

Description

Technical Field

[0001] The present invention relates to a saw wire and a cutting device including the saw wire.

Background Art

[0002] Conventionally, a multi-wire saw that slices a silicon ingot using a wire made of a piano wire is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a wire saw, chips corresponding to the wire diameter are generated. In the above conventional multi-wire saw, a wire made of a piano wire is used, but it is difficult to make the piano wire thinner. Specifically, at present, it is difficult to manufacture a piano wire with a wire diameter smaller than 60 μm, and since the elastic modulus of the piano wire is 150 GPa to 250 GPa, even if it could be thinned, runout would occur during slicing. For this reason, a thinned piano wire is not suitable for slicing with a wire saw.

[0005] Therefore, an object of the present invention is to provide a saw wire capable of reducing the loss of an object to be cut and a cutting device including the saw wire.

Means for Solving the Problems

[0006] To achieve the above object, a saw wire according to one aspect of the present invention includes a metal wire made of pure tungsten. The surface roughness Ra of the metal wire is greater than 0.05 μm and less than or equal to 0.15 μm. The elastic modulus of the metal wire is 350 GPa or more and 450 GPa or less. The tensile strength of the metal wire is 3500 MPa or more and 6000 MPa or less. The wire diameter of the metal wire is 10 μm or more and 60 μm or less.

[0007] Further, a cutting device according to one aspect of the present invention includes the saw wire.

Effect of the Invention

[0008] According to the present invention, it is possible to provide a saw wire capable of reducing the loss of an object to be cut and a cutting device including the saw wire.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0010] Hereinafter, a saw wire and a cutting device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangements and connection forms of components, steps, orders of steps, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Thus, among the components in the following embodiments, components not described in the independent claims indicating the most general concept of the present invention are described as optional components.

[0011] In addition, each figure is a schematic diagram and is not necessarily drawn precisely. Therefore, for example, scales etc. in each figure do not necessarily match. Also, in each figure, substantially the same configurations are given the same reference signs, and overlapping explanations are omitted or simplified.

[0012] Moreover, in this specification, terms indicating the relationship between elements such as parallel or equal, terms indicating the shape of elements such as circular, and numerical ranges are not expressions representing only a strict meaning, but are expressions meaning substantially equivalent ranges, for example, including a difference of about several percent.

[0013] (Embodiment) [Cutting device] First, an overview of the cutting device equipped with a saw wire according to this embodiment will be described with reference to FIG. 1. FIG. 1 is a perspective view of the cutting device 1 according to this embodiment.

[0014] As shown in FIG. 1, the cutting device 1 is a multi-wire saw equipped with a saw wire 10. The cutting device 1 manufactures wafers, for example, by cutting an ingot 20 into thin plates. The ingot 20 is, for example, a silicon ingot composed of single-crystal silicon. Specifically, the cutting device 1 simultaneously manufactures a plurality of silicon wafers by slicing the ingot 20 with the saw wire 10.

[0015] Note that the ingot 20 is not limited to a silicon ingot, and may be other ingots such as silicon carbide or sapphire. Alternatively, the object to be cut by the cutting device 1 may be concrete or glass etc.

[0016] As shown in FIG. 1, the cutting device 1 further includes two guide rollers 2, a support portion 3, and a tension relaxation device 4.

[0017] One saw wire 10 is wound around two guide rollers 2 a plurality of times. Here, for the sake of explanation, one round of the saw wire 10 is regarded as one saw wire 10, and it will be described as if a plurality of saw wires 10 are wound around two guide rollers 2. That is, in the following description, the plurality of saw wires 10 form one continuous saw wire 10. Note that the plurality of saw wires 10 may be a plurality of individually separated saw wires.

[0018] The two guide rollers 2 rotate the plurality of saw wires 10 at a predetermined speed by rotating with the plurality of saw wires 10 stretched straight at a predetermined tension. The plurality of saw wires 10 are arranged parallel to each other and at equal intervals. Specifically, each of the two guide rollers 2 is provided with a plurality of grooves for inserting the saw wire 10 at a predetermined pitch. The pitch of the grooves is determined according to the thickness of the wafer to be cut out. The width of the groove is substantially the same as the wire diameter φ of the saw wire 10.

[0019] The tension relaxation device 4 is a device that relaxes the tension applied to the saw wire 10. For example, the tension relaxation device 4 is an elastic body such as a coil spring or a leaf spring. As shown in FIG. 1, for example, the tension relaxation device 4 which is a coil spring has one end connected to the guide roller 2 and the other end fixed to a predetermined wall surface. By adjusting the position of the tension relaxation device 4 with respect to the guide roller 2, the tension applied to the saw wire 10 can be relaxed.

[0020] Note that the cutting device 1 may include three or more guide rollers 2. A plurality of saw wires 10 may be wound around the three or more guide rollers 2.

[0021] The support portion 3 supports the ingot 20 which is the object to be cut. The support portion 3 extrudes the ingot 20 toward the plurality of saw wires 10, so that the ingot 20 is sliced by the plurality of saw wires 10.

[0022] Incidentally, although not shown, the cutting device 1 may be a cutting device of the free abrasive grain type and may include a supply device that supplies slurry to a plurality of saw wires 10. The slurry is a coolant or the like in which abrasive grains are dispersed. By the abrasive grains contained in the slurry adhering to the saw wire 10, the ingot 20 can be easily cut. The abrasive grains are, for example, diamond or CBN (cubic boron nitride).

[0023] FIG. 2 is a cross-sectional view showing the state of slicing the ingot 20 by the cutting device 1 according to the present embodiment. FIG. 2 is a cross-section taken along line II-II shown in FIG. 1 and shows a part of a cross-section orthogonal to the extending direction of the saw wire 10. Specifically, it shows the state of slicing the ingot 20 by three of the plurality of saw wires 10.

[0024] By extruding the ingot 20 toward the plurality of saw wires 10, the ingot 20 is simultaneously divided into a plurality of divided pieces 21 by the plurality of saw wires 10. The gap 22 between adjacent divided pieces 21 is a space formed by the ingot 20 being scraped off by the saw wire 10. That is, the size of the gap 22 corresponds to the loss of the ingot 20.

[0025] The width d of the gap 22 depends on the wire diameter φ of the saw wire 10. That is, the larger the wire diameter φ of the saw wire 10, the larger the width d and the greater the loss of the ingot 20. The smaller the wire diameter φ of the saw wire 10, the smaller the width d and the smaller the loss of the ingot 20.

[0026] Specifically, the width d of the gap 22 is larger than the wire diameter φ. The difference between the width d and the wire diameter φ is a magnitude that depends on the size of the abrasive grains adhering to the saw wire 10 and the amplitude of the vibration during the rotation of the saw wire 10. At this time, the amplitude of the swing of the saw wire 10 can be suppressed by strongly stretching the saw wire 10. The higher the tensile strength of the saw wire 10 and the larger the elastic modulus, the more possible it is to strongly stretch the saw wire 10. For this reason, the amplitude of the swing of the saw wire 10 becomes smaller, the width d of the gap 22 can be made smaller, and the loss of the ingot 20 can be further reduced.

[0027] Incidentally, the thickness D of the divided piece 21 depends on the arrangement interval of the plurality of saw wires 10. For this reason, the plurality of saw wires 10 are arranged at an interval obtained by adding a desired thickness D and a predetermined margin. Specifically, the margin is the difference between the width d and the wire diameter φ, and is a value determined according to the amplitude of the swing of the saw wire 10 and the particle size of the abrasive grains.

[0028] From the above, it can be seen that the wire diameter φ, the tensile strength, and the elastic modulus of the saw wire 10 are important parameters in order to reduce the loss of the ingot 20. Specifically, the loss of the ingot 20 can be reduced by reducing the wire diameter φ of the saw wire 10, or increasing the tensile strength of the saw wire 10, or increasing the elastic modulus.

[0029] Also, the smaller the surface roughness Ra of the saw wire 10, the more uniform the stress applied to the ingot 20. For this reason, the ingot 20 can be cut smoothly. Therefore, when the surface roughness Ra is small, the amplitude of the swing of the saw wire 10 can also be made small, and the loss of the ingot 20 can be reduced.

[0030] Hereinafter, the configuration and manufacturing method of the saw wire 10 will be described.

[0031] [Saw Wire] The saw wire 10 according to this embodiment includes a metal wire made of an alloy (ReW) of rhenium (Re) and tungsten (W). In this embodiment, the saw wire 10 is the metal wire itself.

[0032] The saw wire 10 contains tungsten as a main component and contains rhenium at a predetermined ratio. The content rate of rhenium in the saw wire 10 is 0.1 wt% or more and 10 wt% or less. For example, the content rate of rhenium may be 0.5 wt% or more and 5 wt% or less, and as an example, it is 3 wt%, but it may also be 1 wt%. By increasing the content rate of rhenium, the tensile strength of the saw wire 10 increases. On the other hand, when the content rate of rhenium is too high, it becomes difficult to make the saw wire 10 thinner.

[0033] The metal wire made of the ReW alloy has a higher strength per cross-sectional area as the wire diameter becomes smaller. That is, by using the metal wire made of the ReW alloy, it is possible to realize the saw wire 10 having a small wire diameter φ, high tensile strength, and high elastic modulus, and suppress the loss of the ingot 20.

[0034] Specifically, the tensile strength of the saw wire 10 is 3500 MPa or more. For example, the tensile strength of the saw wire 10 is 3500 MPa or more and 6000 MPa or less, but it is not limited to this. For example, the tensile strength of the saw wire 10 may be 4000 MPa or more, or may be 5000 MPa or less.

[0035] Also, the elastic modulus of the saw wire 10 is 350 GPa or more and 450 GPa or less. The elastic modulus is the longitudinal elastic modulus. That is, the saw wire 10 has an elastic modulus about twice that of a piano wire.

[0036] The wire diameter φ of the saw wire 10 is 60 μm or less. For example, the wire diameter φ of the saw wire 10 may be 40 μm or less, or may be 30 μm or less. Specifically, the wire diameter φ of the saw wire 10 is 20 μm, but it may also be 10 μm. The saw wire 10 has a uniform wire diameter φ. Since the wire diameter φ of the saw wire 10 is 60 μm or less, the saw wire 10 has flexibility and is easily bent sufficiently. Therefore, the saw wire 10 can be easily wound between the guide rollers 2.

[0037] In addition, the saw wire 10 can also be used in a cutting device of the fixed abrasive grain type. For example, abrasive grains such as diamond particles may be fixed on the surface. In this case, when the wire diameter φ of the saw wire 10 is too small, there is a risk that the abrasive grains are likely to detach. Therefore, for example, the wire diameter φ of the saw wire 10 may be 10 μm or more.

[0038] The saw wire 10 is, for example, a metal wire having a circular cross-sectional shape perpendicular to the extending direction of the wire, but is not limited thereto. The cross-sectional shape of the saw wire 10 may be a rectangle such as a square or an ellipse.

[0039] The surface roughness Ra of the saw wire 10 is 0.15 μm or less. In addition, the surface roughness Ra may be 0.10 μm or less. When abrasive grains are fixed on the surface of the saw wire 10, the adhesion force of the abrasive grains can be increased by forming a plating layer. At this time, when the surface roughness Ra is too small, the adhesion of the plating layer deteriorates. Therefore, the surface roughness Ra of the saw wire 10 may be larger than 0.05 μm, for example.

[0040] [Manufacturing method of saw wire] Hereinafter, the manufacturing method of the saw wire 10 having the above characteristics will be described with reference to FIG. 3. FIG. 3 is a transition diagram showing the manufacturing method of the saw wire 10 according to the present embodiment.

[0041] First, as shown in Fig. 3(a), tungsten powder 11a and rhenium powder 11b are prepared at a predetermined ratio. Specifically, rhenium powder 11b is prepared in the range of 0.1% or more and 10% or less of the total weight of the combined tungsten powder 11a and rhenium powder 11b, and the remainder is tungsten powder 11a. The average particle diameter of each of the tungsten powder 11a and the rhenium powder 11b is, for example, 5 μm, but is not limited thereto.

[0042] Next, by performing pressing and sintering (sintering) on the mixture of the tungsten powder 11a and the rhenium powder 11b, a ReW ingot made of an alloy of tungsten and rhenium is produced. By performing swaging processing, which compresses and stretches from the surroundings, on the ReW ingot, a wire-shaped ReW wire 12 is produced as shown in Fig. 3(b). For example, the ReW ingot, which is a sintered body, has a wire diameter of about 15 mm, while the wire-shaped ReW wire 12 has a wire diameter of about 3 mm.

[0043] Next, as shown in Fig. 3(c), wire drawing processing using a wire drawing die is performed.

[0044] Specifically, first, as shown in Fig. 3(c1), the ReW wire 12 is annealed. Specifically, not only is the ReW wire 12 directly heated with a burner, but it is also heated while passing an electric current through the ReW wire 12. The annealing process is performed to remove the processing strain generated by the swaging process or the wire drawing process.

[0045] Next, as shown in Fig. 3(c2), wire drawing, that is, wire stretching, of the ReW wire 12 is performed using the wire drawing die 30. Since the ReW wire 12 has been heated and softened by the previous annealing process, wire stretching can be easily performed. As the ReW wire 12 is thinned, the strength per unit cross-sectional area increases. That is, the ReW wire 13 thinned by the wire drawing process has a higher tensile strength per unit cross-sectional area than the ReW wire 12. The wire diameter of the ReW wire 13 is, for example, 0.6 mm, but is not limited thereto.

[0046] Next, as shown in (c3) of FIG. 3, electrolytic polishing is performed on the ReW wire 13 after wire drawing to smooth the surface of the ReW wire 13. The electrolytic polishing process is carried out by applying an electric current between the ReW wire 13 and the counter electrode 41, such as a carbon rod, while immersing the ReW wire 13 and the counter electrode 41 in an electrolyte 40, such as an aqueous sodium hydroxide solution.

[0047] Next, as shown in (c4) of FIG. 3, die exchange is performed. Specifically, as the die to be used for the next wire drawing process, a wire drawing die 31 with a smaller diameter than the wire drawing die 30 is selected. Note that the wire drawing dies 30 and 31 are diamond dies made of, for example, sintered diamond or single crystal diamond.

[0048] Steps (c1) to (c4) of FIG. 3 are repeated until the wire diameter of the ReW wire 13 reaches the desired wire diameter (specifically, 60 μm or less). At this time, in the wire drawing process shown in (c2) of FIG. 3, according to the wire diameter of the target ReW wire, the shape and hardness of the wire drawing die 30 or 31, the lubricant used, and the temperature of the ReW wire are adjusted.

[0049] Similarly, in the annealing process shown in (c1) of FIG. 3, the annealing conditions are adjusted according to the wire diameter of the target ReW wire. Oxides adhere to the surface of the ReW wire during the annealing process. By adjusting the annealing conditions, the amount of adhered oxides can be adjusted.

[0050] Specifically, the larger the wire diameter φ of the ReW wire, the higher the annealing temperature, and the smaller the wire diameter φ of the ReW wire, the lower the annealing temperature. For example, when the wire diameter φ of the ReW wire is large, specifically, in the annealing process during the first wire drawing process, annealing is performed at a temperature of 1400°C to 1800°C. In the final annealing process during the final wire drawing process to the desired wire diameter, heating is performed at a temperature of 1200°C to 1500°C. Note that in the final annealing process, it is not necessary to apply an electric current to the ReW wire.

[0051] Also, during repeated wire drawing processes, the annealing process may be omitted. For example, the final annealing process may be omitted. Specifically, the final annealing process may be omitted, and the lubricant and the shape and hardness of the wire drawing die may be adjusted.

[0052] Also, in the wire drawing process after the final annealing (i.e., the final wire drawing process), a single crystal diamond die composed of single crystal diamond is used as the wire drawing die 31. In a single crystal diamond die, detachment of diamond particles is less likely to occur, so wire streaks are less likely to be formed on the ReW wire after wire drawing. Therefore, the surface roughness Ra of the ReW wire having the desired wire diameter can be reduced.

[0053] Also, during repeated wire drawing processes, for example, starting wire drawing from a single crystal diamond die with a hole diameter of 200 μm with the weight ratio of the oxide amount at the 50MG time point being 0.2% or more and 0.5% or less. Thereby, as shown in FIG. 3(d), the saw wire 10 with a surface roughness Ra of 0.15 μm or less is manufactured.

[0054] Note that FIG. 3 schematically shows each process of the method for manufacturing the saw wire 10. Each process may be performed individually or in-line. For example, a plurality of wire drawing dies are arranged on the production line in the order of decreasing aperture size in sequence, and a heating device and an electrolytic polishing device for performing an annealing process may be arranged between each wire drawing die.

[0055] [Effects, etc.] As described above, the saw wire 10 according to the present embodiment includes a metal wire made of a tungsten alloy. The surface roughness Ra of the metal wire is 0.15 μm or less, the elastic modulus of the metal wire is 350 GPa or more and 450 GPa or less, the tensile strength of the metal wire is 3500 MPa or more, and the wire diameter φ of the metal wire is 60 μm or less. Also, for example, the tensile strength of the metal wire is 6000 MPa or less.

[0056] Thus, since the metal wire contains tungsten as the main component, the thinner the wire becomes, the greater the tensile strength and the more difficult it is to break. As a result, since the metal wire becomes less likely to break even when thinned, it is possible to realize a metal wire that is thinner than a piano wire, has a tensile strength equal to or greater than that of a piano wire, and has an elastic modulus approximately twice that of a piano wire.

[0057] Since the saw wire 10 according to the present embodiment has a high tensile strength, it can be stretched between the guide rollers 2 with a strong tension. Therefore, the vibration of the saw wire 10 during the cutting of the ingot 20 can be suppressed.

[0058] Also, since the surface roughness Ra of the saw wire 10 is small, the stress applied to the ingot 20 is made uniform. Therefore, the ingot 20 can be cut smoothly. Thus, when the surface roughness Ra is small, the swing width of the saw wire 10 can also be made small, and the loss of the ingot 20 can be further reduced.

[0059] As described above, since the wire diameter φ and the surface roughness Ra of the saw wire 10 are small, and the tensile strength and the elastic modulus are large, the chips generated when the ingot 20 is sliced, that is, the loss of the ingot 20 can be reduced. Therefore, the number of wafers cut out from one ingot 20 can be increased.

[0060] Further, in the saw wire 10 according to the present embodiment, for example, the tungsten alloy is an alloy of rhenium and tungsten, and the content of rhenium in the tungsten alloy is 0.1 wt% or more and 10 wt% or less.

[0061] Thereby, since the metal wire contains rhenium, the tensile strength can be increased compared to a pure tungsten wire. Also, compared to the case of pure tungsten, irregularities such as wire streaks are less likely to occur in the metal wire during wire drawing. Therefore, the surface roughness Ra of the metal wire can be easily reduced.

[0062] Since the alloy wire of rhenium tungsten has the characteristic that the tensile strength per cross-sectional area increases with wire thinning, it is very useful that the saw wire 10 is composed of an alloy wire of rhenium tungsten.

[0063] Further, the cutting device 1 according to the present embodiment includes, for example, a saw wire 10.

[0064] As a result, since the wire diameter φ of the saw wire 10 becomes smaller, the number of wafers cut out from one ingot 20 can be increased. Also, the amount of chips generated when the ingot 20 is sliced can be reduced.

[0065] Further, the cutting device 1 according to the present embodiment further includes, for example, a tension relaxation device 4 that relaxes the tension applied to the saw wire 10.

[0066] As a result, it is possible to suppress the application of strong tension to the saw wire 10, so that it is possible to suppress breakage of the saw wire 10 and the like.

[0067] (Modification example) Subsequently, a modification example of the above embodiment will be described. Hereinafter, the description will focus on the differences from the above embodiment, and the description of the common points will be omitted or simplified.

[0068] The saw wire according to this modification example includes a metal wire made of tungsten doped with potassium (K) instead of the ReW alloy. The saw wire according to this modification example is the metal wire itself.

[0069] The saw wire contains tungsten as a main component and contains potassium at a predetermined ratio. The potassium content of the saw wire is 0.005 wt% or more and 0.010 wt% or less.

[0070] A metal wire made of potassium-doped tungsten (potassium-doped tungsten wire) has a higher tensile strength per cross-sectional area as the wire diameter φ decreases. That is, by using a potassium-doped tungsten wire, a saw wire with a small wire diameter φ and a high tensile strength can be realized, and the loss of the ingot 20 can be suppressed.

[0071] The tensile strength, elastic modulus, wire diameter φ, surface roughness Ra, etc. of the saw wire according to this modification example are the same as those of the saw wire 10 according to the embodiment.

[0072] As described above, in the saw wire according to this modification example, potassium is doped in the metal wire made of tungsten, and the potassium content of the metal wire is 0.005 wt% or more and 0.010 wt% or less.

[0073] In this way, when tungsten contains a trace amount of potassium, the grain growth in the radial direction of the metal wire is suppressed. Therefore, the saw wire according to this modification example has a higher strength at high temperatures than pure tungsten.

[0074] Also, the potassium-doped tungsten wire has a higher strength per cross-sectional area as the wire diameter decreases. Therefore, as in the case of the ReW alloy, by using a potassium-doped tungsten wire, the surface of the metal wire is less likely to be scratched and is easier to smooth. That is, a metal wire with a surface roughness Ra of 0.15 μm or less can be easily manufactured.

[0075] (Others) As described above, the saw wire and the cutting device according to the present invention have been described based on the above embodiments and their modification examples. However, the present invention is not limited to the above embodiments.

[0076] For example, in the above embodiment, an alloy of rhenium and tungsten is shown as the tungsten alloy. However, for example, an alloy of nickel (Ni) and tungsten may also be used.

[0077] Further, for example, in the above-described embodiment, an example where the saw wire 10 (i.e., a metal wire) is made of a tungsten alloy has been shown, but it is not limited thereto. The saw wire 10 may be composed of tungsten. That is, the saw wire may be composed of pure tungsten. The purity of tungsten is, for example, 99.9% or more, but it is not limited thereto.

[0078] Further, for example, in the above-described embodiment, an example where the saw wire 10 is the metal wire itself has been shown, but it is not limited thereto. The saw wire 10 may include a metal wire and a plurality of abrasive grains fixed to the surface of the metal wire. That is, the saw wire 10 may be a wire used in the free abrasive grain type cutting device 1 as shown in the embodiment, or may be a wire used in a fixed abrasive grain type cutting device. The abrasive grains are, for example, diamond or CBN (cubic boron nitride).

[0079] In the case of the fixed abrasive grain method, since the surface roughness Ra of the metal wire is small, when the abrasive grains are fixed to the metal wire, the stress applied to the abrasive grains during slicing of the ingot 20 is likely to be evenly dispersed. For this reason, detachment of the abrasive grains from the metal wire can be suppressed, so that a decrease in the sharpness of the saw wire 10 can be suppressed. Further, the stress applied to the ingot 20 via the abrasive grains is also likely to be evenly dispersed. For this reason, the ingot 20 can be sliced smoothly, the vibration of the saw wire 10 is suppressed, and thus the loss of the ingot 20 can be reduced.

[0080] Further, for example, the cutting device 1 does not have to be a multi-wire saw, and may be a wire saw device that slices the ingot 20 with one saw wire 10 to cut out wafers one by one. Also, the cutting device 1 shown in FIG. 1 is merely an example, and for example, it does not have to include the tension relaxation device 4.

[0081] In addition, forms obtained by applying various modifications that occur to those skilled in the art to each embodiment, and forms realized by arbitrarily combining the components and functions in each embodiment without departing from the spirit of the present invention are also included in the present invention.

Explanation of Signs

[0082] 1 Cutting device 10 Saw wire

Claims

1. comprising a metal wire made of pure tungsten, the surface roughness Ra of the metal wire is greater than 0.05 μm and less than or equal to 0.15 μm, the elastic modulus of the metal wire is 350 GPa or more and 450 GPa or less, the tensile strength of the metal wire is 4000 MPa or more and 6000 MPa or less, the wire diameter of the metal wire is 10 μm or more and 60 μm or less saw wire.

2. A cutting device comprising the saw wire according to Claim 1.

3. Further comprising a tension relief device for relieving the tension applied to the saw wire The cutting device according to Claim 2.

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