JP5991267B2 - Work cutting method and cutting device - Google Patents

Description

  The present invention relates to a cutting method and a cutting apparatus for cutting a workpiece into a wafer shape with a wire saw.

One of the cutting devices for cutting a hard and brittle material such as a semiconductor ingot into a thin wafer is a wire saw.
A wire saw runs at a high speed through a wire array stretched at a predetermined pitch, presses the workpiece against the wire array, and simultaneously blows loose abrasive grains onto the portion where the wire and the workpiece are in contact, and simultaneously cuts into multiple wafers. Device.

  Patent Document 1 discloses a wire used in which the outer peripheral surface of the wire is coated with an abrasive carrier resin film. If this wire is used, the abrasive grains (free abrasive grains) bite into the abrasive carrier resin film, so that the abrasive grains can be stably drawn into the portion where the wire and the workpiece are in contact.

  Patent Document 2 describes that a predetermined amount of processing slurry can be attached to the wire by performing pretreatment means for roughening the surface of the wire by spraying abrasive grains. .

JP 2006-179677 A Japanese Patent Application Laid-Open No. 11-099462 JP 2011-5624 A

  When the silicon single crystal ingot is cut using the coated wire of the resin film described in Patent Document 1, the surface roughness and damage of the cut wafer are compared with conventional free abrasive grain cutting with a piano wire without a resin film. Although good quality can be obtained at the depth, the waviness and warpage indicating the entire shape of the wafer are inferior. This is due to the small number of abrasive grains that bite into the abrasive carrier resin film during cutting.

  The waviness and warpage of the cut wafer is generally caused by the meandering of the wire. Even in the cutting method of cutting the workpiece by cutting the abrasive particles into the abrasive carrier resin film, if there is a small amount of abrasive particles that bite into the abrasive carrier resin film, the abrasive grains will be biased, causing the wires to meander and swell. And warpage gets worse.

  The surface of the covered wire described in Patent Document 1, that is, the surface of the abrasive carrier resin film, is smooth and glossy with no irregularities. When processing is started in such a surface state, the number of abrasive grains that bite into the abrasive carrier resin film is reduced, and the deviation of the abrasive grains that bite occurs, resulting in strong undulation and warpage.

  Moreover, even if the pretreatment means of the abrasive grain or slurry spraying method described in Patent Document 2 is applied to the coated wire, the abrasive carrier resin film is more flexible than a general piano wire surface, so And suppression of warpage cannot be expected.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a workpiece cutting method and a cutting apparatus that can improve the overall shape of the cut wafer such as waviness and warpage.

  In order to achieve the above object, according to the present invention, a wire row formed by wires wound spirally between a plurality of wire guides is caused to travel in the axial direction, and the cylindrical workpiece and the wire are brought into contact with each other. A workpiece cutting method in which the workpiece is pressed against the wire row and fed into the wafer row while supplying a machining fluid to the section, and the workpiece is cut into a wafer shape. A surface-roughening member for roughening the surface of the wire is disposed on the wire operation side of the wire row from the workpiece to be cut, using a coating film, and the wire and the surface-roughening member A workpiece cutting method characterized by cutting the workpiece while roughening the surface of the wire by bringing the wire into contact with each other.

  With such a cutting method, the coated wire used for workpiece cutting comes into contact with the roughening member before coming into contact with the workpiece, so that the coating on the surface of the coated wire is roughened and the abrasive bites into the coating. The number of grains can be greatly increased. As a result, the covered wire can be cut linearly, and the overall shape of the cut wafer, such as waviness and warpage, can be greatly improved. Moreover, since the wire has a film, the quality of the surface roughness and damage depth of the cut wafer is improved.

At this time, the roughening member is preferably any one of resin, silicon, carbon, and ceramics.
In this way, the wire can be roughened satisfactorily, the wear of the roughened member can be suppressed, the life of the roughened member can be prolonged, and the cost can be reduced.

  Further, according to the present invention, the machining fluid is supplied to a wire row formed by a wire that is wound spirally between a plurality of wire guides and travels in an axial direction, and a contact portion between the cylindrical workpiece and the wire. A nozzle, and a workpiece feeding means for pressing the workpiece against the wire row by pressing the workpiece while holding the workpiece, while supplying a working fluid from the nozzle to the contact portion between the workpiece and the wire, A workpiece cutting device that presses and feeds the workpiece held by the workpiece feeding means to the traveling wire row and cuts the workpiece into a wafer shape, wherein the wire is formed on the surface of the base wire with an organic film or An inorganic film is coated, and a roughening member for roughening the surface of the wire is provided on the wire operation side of the wire row from the workpiece. By contacting Ya and the roughening member, the cutting device of a work which is characterized in that the wire surface is to cut the workpiece while roughening is provided.

  If this is the case, the coated wire used for cutting the workpiece comes into contact with the roughening member before coming into contact with the workpiece, so that the coating on the surface of the coated wire is roughened and the abrasive grains bite into the coating. The number can be increased significantly. As a result, the coated wire can be cut linearly, greatly improving the overall shape of the cut wafer, such as undulation and warping, and improving the surface roughness and damage depth of the cut wafer. it can.

At this time, it is preferable that the roughening member is any one of resin, silicon, carbon, and ceramics.
With such a configuration, the wire can be uniformly roughened, wear of the roughened member can be suppressed, the life of the roughened member can be extended, and cost can be reduced.

  In the present invention, when a workpiece is cut by a wire saw, a base wire surface coated with an organic film or an inorganic film is used as a cutting wire. Then, a roughening member for roughening the wire surface is arranged on the wire operation side of the wire row from the workpiece to be cut, and the wire surface is roughened by bringing the wire and the roughening member into contact with each other. The workpiece is cut while making it. By doing in this way, the coating | coated film | membrane on the surface of a covering wire is roughened, an unevenness | corrugation is made in a coating | film | coat, and the number of the abrasive grains which bite into a coating | film | coat can be increased significantly. As a result, the wire can be cut linearly. As a result, the overall shape of the cut wafer, such as waviness and warpage, can be greatly improved. Moreover, since the wire has a film, the quality of the surface roughness and damage depth of the cut wafer is improved.

It is the schematic which showed an example of the workpiece | work cutting device which concerns on this invention. It is the enlarged view which showed the principal part of the cutting device of the workpiece | work which concerns on this invention. It is a SEM photograph which shows an example of the covering wire without a contact with a roughening member. It is a SEM photograph which shows an example of the covering wire after contact with a roughening member.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
As described above, when a silicon single crystal ingot is cut using a wire coated with a resin film, the surface roughness of the cut wafer is compared with conventional free abrasive grain cutting with a piano wire without a resin film. Although good quality was obtained at the sheath depth, there was a problem that the waviness and warpage indicating the entire shape of the wafer deteriorated.

  Therefore, the present inventor diligently studied in order to suppress the deterioration of the overall shape such as the waviness and warpage of the wafer while obtaining a good quality of the surface roughness and damage depth of the cut wafer when cutting the workpiece with a wire saw Repeated. As a result, a coated wire with an organic film or an inorganic film coated on the surface of the base wire is used as the wire, and the coated wire surface, that is, the coated surface is roughened on the wire operation side of the wire row from the workpiece to be cut. By placing the roughened member and bringing the coated wire and the roughened member into contact with each other, cutting the workpiece while roughening the surface of the coated wire makes it possible to shape the entire shape of the cut wafer, such as undulation and warpage. The present invention was completed by conceiving that it can be greatly improved.

  Hereinafter, although the cutting method of the workpiece | work of this invention is demonstrated in detail with reference to figures, this invention is not limited to these.

The workpiece cutting device of the present invention will be described.
As shown in FIG. 1, the cutting device 1 of the present invention mainly includes a wire row 4 formed by a covered wire 3 that is spirally wound between a plurality of wire guides 2 and travels in an axial direction. The working fluid supply means 5 for supplying the working fluid to the contact portion between W and the covered wire 3, the workpiece feeding means 6 for pressing the workpiece W against the wire row by pressing the workpiece W while holding the workpiece W, and tension on the covered wire 3 It is comprised by the tension | tensile_strength provision mechanisms 7 and 7 'for providing.

The covered wire 3 is obtained by coating the base wire surface with an organic film or an inorganic film. The film is not particularly limited, but the organic film is, for example, a thermosetting resin such as phenol, polyamide, epoxy, or urethane, or photocurable such as epoxy or urethane. Resin can be used. As the inorganic film, for example, a SiO ₂ film, a glass (soda glass) film, a CrN film, or the like can be used (Patent Document 3).

  The covered wire 3 is fed out from one wire reel bobbin 8 and enters the wire guide 2 via a traverser and a tension applying mechanism 7 including a constant torque motor, a dancer roller (dead weight), and the like. The covered wire 3 is wound around a wire reel bobbin 8 'through another tension applying mechanism 7'.

  The processing liquid supply means 5 includes a slurry chiller 9, a slurry tank 10, a nozzle 11 and the like. The nozzle 11 is disposed above the covered wire 3 wound around the wire guide 2. The nozzle 11 is connected to the slurry tank 10, and the machining liquid is stirred in the slurry tank 10 and adjusted in temperature by the slurry chiller 9, and then can be supplied from the nozzle 11 to the covered wire 3. Then, the machining fluid rides on the wire row 4 and is sent to the contact portion between the workpiece W and the wire row 4. Further, the supplied machining fluid is returned to the slurry tank 10 for circulation.

  Further, the wire guide 2 is a roller in which polyurethane resin is press-fitted around a steel cylinder and grooves are cut at a predetermined pitch on the surface thereof, and the covered wire 3 wound by the drive motor 12 is reciprocated in the axial direction. You can run. Here, when the covered wire 3 is reciprocally traveled, the travel distance in both directions of the covered wire 3 is not the same so that a new wire is supplied, but the travel distance in one direction is longer. Like that. In this way, a new line is supplied in the direction of a long travel distance while reciprocating the covered wire 3.

For example, as shown in FIG. 2, when a new line is supplied in the A direction, the B side shown in FIG. 2 is the wire steering side, and the C side is the wire winding side.
Further, as shown in FIG. 2, a roughening member 14 for roughening the surface of the covered wire 3 on the wire operation side (B side in FIG. 2) of the wire row 4 from the work W, and the roughening member 14 A roughening member container 13 for holding the surfaceizing member 14 is provided. The roughening member container 13 is made of stainless steel, and is fixed to a block (not shown) for fixing the wire guide 2, and the container part is opened on the wire row 4 side. The roughening member 14 held in the opening of the roughening member container 13 and the covered wire 3 can come into contact with each other. Further, a spring (not shown) is installed in the roughening member container 13, and even if the roughening member 14 is worn, it can be fed out in the direction of the wire row 4 with a constant pressing pressure.

  When cutting the workpiece W, the workpiece W held by the workpiece feeding means 6 is pressed against the traveling wire row 4 while supplying the machining fluid from the nozzle 11 to the contact portion between the workpiece W and the covered wire 3. Cut and feed to cut the workpiece W into a wafer. At this time, in the present invention, since the covered wire 3 comes into contact with the roughening member 14 on the wire operation side (B side in FIG. 2) of the wire row 4 from the work W, the covered wire 3 in contact with the work W is The coating surface is roughened.

  With such a workpiece cutting device of the present invention, the coated wire used for workpiece cutting comes into contact with the roughening member before contacting the workpiece, so that the coating on the surface of the coated wire is roughened. The number of abrasive grains that bite into the film can be greatly increased, the deviation of the abrasive grains that bite into the film is reduced, and the meandering of the wire is reduced. Therefore, the covered wire can be cut straight. As a result, good quality can be obtained in terms of the surface roughness and damage depth of the cut wafer, and at the same time, the overall shape such as waviness and warpage can be greatly improved.

At this time, it is preferable that the roughening member 14 is any one of resin, silicon, carbon, and ceramics.
In this way, the roughening can be performed uniformly and easily, the wear of the roughening member 14 can be suppressed, the life of the roughening member 14 can be prolonged, and the cost can be reduced. It will be a thing.

Next, the workpiece cutting method of the present invention will be described. Here, the case where the cutting device 1 as shown in FIG. 1 is used will be described.
First, as shown in FIG. 2, the roughening member 14 held by the roughening member container 13 is arranged on the wire operation side of the wire row 4 from the workpiece W so as to be in contact with the covered wire 3. Next, the workpiece W is held by the workpiece feeding means 6. The coated wire 3 is reciprocated in the axial direction while applying tension by the tension applying mechanisms 7 and 7 ′, and the workpiece feeding means 6 is supplied with the machining liquid supplied to the coated wire 3 by the machining liquid supply means 5. Thus, the workpiece W is relatively pushed down, and the workpiece W is cut and fed into the wire row 4 to cut the workpiece W.

  At this time, by bringing the coated wire 3 into contact with the roughening member 14 on the wire operation side of the wire row 4 from the workpiece W, the coating surface of the coated wire 3 before contacting with the workpiece W is always roughened. To be in a state. The new line supplied from the wire feeding side can always be roughened by this method, but the wire used for cutting immediately after the start of cutting of the workpiece W is roughened, for example, after wire replacement. It is preferable that the unfinished wire is roughened in advance by the roughening member 14. This can be easily performed using the apparatus of the present invention.

  With such a workpiece cutting method, the coated wire used for workpiece cutting comes into contact with the roughening member before coming into contact with the workpiece, so that the coating on the surface of the coated wire is roughened. The number of abrasive grains that bite in can be greatly increased, and the bias of the abrasive grains that bite into the film is reduced, thereby reducing the meandering of the wire. Therefore, the covered wire can be cut straight. As a result, good quality can be obtained in terms of the surface roughness and damage depth of the cut wafer, and at the same time, the overall shape such as undulation and warpage can be greatly improved.

At this time, it is preferable that the roughening member is any one of resin, silicon, carbon, and ceramics.
With such a material, the wire can be roughened easily and uniformly, and since it is not excessively roughened, the wear of the roughened member can be suppressed, and the life of the roughened member can be reduced. Can lengthen the cost.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention, but the present invention is not limited to these.

(Example)
Using the cutting apparatus of the present invention as shown in FIG. 1, the work was cut according to the work cutting method of the present invention, and the waviness Wt of the cut wafer was measured. Here, a single crystal silicon ingot having a diameter of 200 mm and a length of 160 mm was used as a workpiece to be cut. The covered wire used was a piano wire with a core wire diameter of 0.14 mm coated with a polyamide resin film having a thickness of 10 μm.

  In addition, a reciprocating travel in which the coated wire is sent to the wire winding side while repeating the forward and backward movements from the wire operating side is adopted. Here, the average traveling speed of the wire was set to 600 m / min, and the supply speed for feeding the new wire was set to 5 m / min. The wire tension was adjusted with a tension applying mechanism and set to 25N.

  As a processing liquid, a slurry in which diamond having an average particle diameter of 8 μm was suspended in a glycol-based aqueous solution was used. The diamond concentration in the slurry was 5% by mass. Moreover, single crystal silicon was used as the roughening member, and the pressing force of the roughening member applied a load of about 0.06 kgf to one wire. This is the value at which the wire array bends about 2 mm.

First, before starting the cutting of the workpiece, the surface condition of the covered wire without contact with the roughened member and the surface of the covered wire after contacting with the roughened member and before contacting with the workpiece were evaluated.
FIG. 3 is an SEM photograph showing a covered wire without contact with the roughening member. As shown in FIG. 3, the covered wire without contact with the roughening member has a glossy and smooth surface state.
FIG. 4 is an SEM photograph showing the coated wire after contact with the roughened member. As shown in FIG. 4, it can be seen that the surface of the coated wire after contact with the roughening member is uneven and roughened.

Next, the workpiece was cut, and the waviness Wt of the cut wafer was measured. For measuring the waviness Wt, a stylus type roughness meter was used. The cutting length was 190 mm and the cutting direction was measured. For the numerical processing after the measurement, a JIS'01 standard filtering swell, a cutoff of 0.8 mm, and a Gaussian filter were used. In the sampling method of the wafer, 5 pieces each were extracted from the wire feeding side and the wire winding side at both ends in the ingot block.
(Comparative example)
The cutting device is not equipped with a roughening member, that is, the workpiece is cut under the same conditions as in the example, except that the workpiece is cut while the coated wire is not roughened as shown in FIG. The waviness Wt of the cut wafer was measured.

Table 1 summarizes the measurement results of Examples and Comparative Examples.
In the comparative example, the undulation on the wire feeding side is inferior to that on the wire winding side. This is because a solid coated wire enters from the wire operation side of the ingot block. However, in the embodiment of the present invention, since the abrasive carrier resin film on the surface of the coated wire is roughened in advance, the difference in waviness due to the position of the ingot block is eliminated, and the waviness improvement of about 30% is achieved compared with the comparative example. .

  In the examples, single crystal silicon was used as the roughening member, but it was confirmed that the same effect can be obtained even if any of resin, silicon, carbon and ceramics is used as the roughening member.

  In addition, the coated wire shown in FIG. 4 was roughened on the entire surface because it was contacted with the roughened member 40 times (20 reciprocations). It has been confirmed that the same effect can be obtained because the roughened portion is mainly involved in workpiece processing.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

DESCRIPTION OF SYMBOLS 1 ... Cutting device, 2 ... Wire guide, 3 ... Coated wire,
4 ... wire row, 5 ... working fluid supply means, 6 ... work feeding means,
7, 7 '... tension applying mechanism, 8, 8' ... wire reel bobbin,
9 ... Slurry chiller, 10 ... Slurry tank, 11 ... Nozzle,
12 ... Drive motor, 13 ... Roughening member container, 14 ... Roughening member,
W ... Work.

Claims (4)

A wire row formed by wires wound spirally between a plurality of wire guides is run in the axial direction, and while supplying a working fluid to a contact portion between a cylindrical workpiece and the wire, A method of cutting a workpiece by pressing and feeding the workpiece and cutting the workpiece into a wafer shape,
The wire base surface of the wire used after coating the organic skin film, the wire Feeding side of the wire row from the work to be the cut, place the roughening member for roughening the surface of the wire The roughening member that can be fed in a wire row direction with a constant pressing force is used, and the wire and the roughening member are brought into contact with each other to roughen the surface of the wire while the workpiece is roughened. A method of cutting a workpiece characterized by cutting the workpiece.   2. The workpiece cutting method according to claim 1, wherein the roughening member is any one of resin, silicon, carbon, and ceramics. A wire array formed by wires running in an axial direction spirally wound between a plurality of wire guides, a nozzle for supplying a machining fluid to a contact portion between a cylindrical workpiece and the wire, and holding the workpiece The workpiece feeding means that presses the workpiece against the wire row by pressing the workpiece while being pressed, while being supplied to the contact portion between the workpiece and the wire from the nozzle, is held by the workpiece feeding means. The workpiece is a workpiece cutting device that presses and feeds the workpiece against the wire row that travels, and cuts the workpiece into a wafer shape,
Said wire is obtained by coating the organic skin layer on the base wire surface, the wire Feeding side of the from the work wire row, comprises roughening member for roughening the wire surface, the rough The chamfering member can be fed out with a constant pressing force in the wire row direction, and the workpiece is cut while the wire surface is roughened by bringing the wire into contact with the roughening member. A workpiece cutting device characterized by being a thing.   4. The workpiece cutting device according to claim 3, wherein the roughening member is one of resin, silicon, carbon, and ceramics.

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