TW202411040A - Method for simultaneously slicing a plurality of slices from a workpiece by means of a wire saw - Google Patents

Abstract

A method for simultaneously slicing a plurality of slices from a workpiece by means of a wire saw, comprising a slicing grinding process, wherein a workpiece is moved perpendicularly to a longitudinal axis of the workpiece towards a wire web of a sawing wire stretched between two wire guide rollers, which sawing wire is moved in the longitudinal direction of the sawing wire, wherein a cooling lubricant is fed to the wire web, and wherein slices which are fastened to a beam, and between which slicing gaps exist, are produced between wire sections of the wire web, and the removal of the beam and the slices from the wire web; characterized by the spraying of the slicing gaps with a fluid by means of a spray device during removal of the beam and the slices, until the wire sections have left the slicing gaps, wherein the fluid is fed at high pressure through nozzles fastened to nozzle brackets which are moved in oscillating fashion parallel to the longitudinal axis of the workpiece, wherein the fluid and the entrained air occasionally stimulate vibration of the slices.

Description

Method for cutting multiple slices from a workpiece simultaneously by means of a wire saw

The object of the invention is a method for simultaneously cutting a plurality of slices from a workpiece by means of a wire saw, comprising: an abrasive cutting process, wherein the workpiece is fed perpendicularly to the longitudinal axis of the workpiece towards a wire web of a sawing line spanning between two wire rollers, the sawing line being moved longitudinally along the sawing line, wherein a cooling lubricant is provided to the wire web, and wherein slices are produced between wire sections of the wire web, the slices being fastened to a beam with a slicing gap therebetween; and removing the beam and the slices from the wire web.

For many applications, uniform slices with good plane-parallelism on both the front and rear sides are required, which have some crystal and structural defects. An example is the slicing of structured single-crystal semiconductor materials for microelectronic components. Such slices are obtained, for example, by cutting from cylindrical workpieces.

Existing Technology/Problems

For example, DE 10 2016 211 883 A1 discloses a method and a device for wire sawing. With wire sawing, a sawing wire is guided in a spiral manner around at least two wire rollers in the following manner: The two wire rollers straddle a wire web facing the workpiece, the wire web consisting of wire segments extending parallel to one another. The side surfaces of the wire rollers are provided with a plurality of annularly closed grooves, which extend in a plane perpendicular to the axis of the wire rollers and guide the sawing wire. Rotating the wire rollers in the same direction produces a relative movement between the wire segments and the workpiece. The wire saw also has a feed device on which the workpiece is fastened via the beam to which it is bonded and which feeds the workpiece perpendicularly to the wire web. When contact is made between the workpiece and the wire web, the relative motion and the presence of abrasive cutting means result in the removal of material from the workpiece. With continuous feed, the wire segments form the cutting gap in the workpiece and the wire web is slowly passed through the entire workpiece until it is completely within the saw beam. The workpiece is then completely cut into slices which are suspended from the beam like the teeth of a comb and held only by adhesive joints.

Once the cutting process has been completed, the sliced workpiece must be retrieved from the wire web by reversing the direction of movement of the infeed device (ingot retrieval).

Wire sawing can be distinguished into wire slicing lapping and wire slicing grinding. In the case of wire slicing lapping, the saw wire is initially free of abrasive agents and the cutting tool is provided in the form of a slurry as freely movable particles dispersed in a carrier fluid. In the case of wire slicing grinding, the abrasive cutting agent is anchored to the surface of the saw wire and a cutting fluid is provided which acts as a cooling lubricant and does not contain any abrasive substances.

Saw wire is usually made of hypereutectoid pearlitic steel (piano wire). Both straight (flat) and structured (crimped) saw wire are used.

In the case of wire-cut grinding, the cutting agent is usually composed of silicon carbide (SiC), and the carrier fluid is usually composed of oil or ethylene glycol. In the case of wire-cut grinding, the cutting agent is usually composed of water, which may contain a wetting agent and an anti-foaming additive, and the abrasive anchored in the saw wire is usually diamond.

With wire sawing, the saw wire is taken from a first stock, usually in the form of a first spool on which the saw wire is wound, and after use is fed into a second stock, usually in the form of a second spool, likewise. The first spool is called the fresh wire spool, and the second spool is called the used wire spool. Wire sawing may involve unidirectional or bidirectional wire movement. In the case of unidirectional wire sawing, the saw wire is moved in the longitudinal wire direction from the fresh wire spool to the used wire spool throughout the cutting process. In the case of wire sawing with bidirectional wire motion, the sawing wire is moved during the cutting process by means of at least one pair of reversals of direction, wherein a pair of reversals of direction comprises a first movement of the sawing wire in a first wire longitudinal direction with a first length and a second movement of the sawing wire in a second direction with a second length, the second direction being diametrically opposite to the first direction. In particular, wire sawing with bidirectional wire motion may comprise a plurality of pairs of such wire direction reversals, wherein the first length is selected to be greater than the second length, such that the entire wire stock is moved from a new wire reel to a used wire reel during the cutting process. The above method is called pilgrim mode slicing or wire-reciprocating slicing.

Wire saws are also known in the art, in which the workpiece can be pivoted during the cutting process about an axis parallel to the longitudinal axis of the workpiece. In particular, this rotational movement can be performed in the form of a continuous sequence of pairs of rotational changes, wherein a pair of rotational changes comprises a clockwise rotation about a first angle at a first angular velocity and a subsequent counterclockwise rotation about a second angle at a second angular velocity. In this case, the first angular velocity and the second angular velocity as well as the first angle and the second angle can also be varied during the cutting process, for example depending on the cutting depth or on the instantaneous length of the saw line in the workpiece. This reciprocating rocking movement of the workpiece is also referred to as rocking of the workpiece. For example, US 2022/0134600 A1 describes a device suitable for this purpose.

During the cutting process, material is removed primarily along the contact surface along which the saw line comes into material-removing contact with the workpiece and which extends in the opposite direction to the workpiece feed direction. This contact surface is called the primary cutting surface. The contact surface where the saw line comes into contact with the workpiece perpendicular to this direction (in other words, along the workpiece axis) is called the secondary cutting surface, and no material is initially removed because no external forces are applied here during the workpiece feed. The sum of all transient secondary cutting surfaces of the cutting gap during the entire cutting process forms the front and back faces of adjacent slice pairs.

During wire sawing without wobble, the main cutting surface extends along the entire arc length from the entry of the sawing line into the cutting gap to the exit of the sawing line from the cutting gap. During wire sawing with wobble, the main cutting surface at any time consists only of short arc segments, by means of which the sawing line touches the cutting line between the workpiece and the cutting gap, which cutting line is bent due to the wobble. The wobble improves the supply of cooling lubricant or slurry to the cutting gap, even in the case of workpieces with large diameters.

With cut-off grinding, the material removal rate is proportional to the pressure on the major cutting faces. With cut-off grinding, the material removal rate increases disproportionately with the pressure on the major cutting faces. Therefore, with the aid of pendulum, cut-off grinding (but not cut-off grinding) can be performed faster than without pendulum.

Removal of the workpiece cut into slices from the wire web occurs after wire sawing by inverting the workpiece feed. In this case, the saw wire is slowly moved longitudinally along the wire and cutting fluid is added in order to draw the cutting fluid into the cutting gap as lubrication and prevent friction of the saw wire in the cutting gap and sticking of individual wire segments between mutually opposite secondary cutting faces of the cutting gap. During blank retrieval after wire EDM grinding, most of the slurry falls off the saw wire due to the slow wire movement before the saw wire enters the cutting gap, so that the thickness of the slurry film surrounding the saw wire in the cutting gap is substantially less than the thickness of the slurry film during the previous cutting process. Therefore, during the stock retrieval after wire EDM grinding, the saw wire has play in the cutting gap and does not stick. This facilitates the wire web to slide evenly through the cutting gap and eventually out of the gap without the saw wire sticking between the secondary cutting surfaces of the gap or causing material to be removed from the secondary cutting surfaces.

In the case of wire EDM grinding, the saw wire is surrounded by no slurry of the cutting tool. Therefore, the width of the kerf is the same as the wire diameter, including the diamond incorporated in the saw wire. Therefore, during blank retrieval, the saw wire has no play in the kerf, which means that it often sticks to different cutting depths. Therefore, the slow longitudinal movement of the wire means that additional material removal occurs immediately and a kerf is formed on the walls of the kerf. Since the walls of the kerf form the front side of one slice and the back side of the adjacent slice, a kerf is formed in a single obtained wafer. Slices with kerfs on the surface are not suitable for demanding applications.

While the saw wire remains stuck to the cutting depth during the stock retrieval after wire EDM grinding, the feed device is further reset. As a result, the saw wire is deflected transversely and thus elastically stretched longitudinally. As a result, the restoring force of the saw wire becomes increasingly greater. When the restoring force has grown sufficiently, the saw wire jumps out of the cutting depth to which it was stuck during the retrieval to a smaller cutting depth to which it sticks again, and so on (stick and slip movement of the saw wire). If the tension exceeds the material strength of the saw wire due to the transverse deflection of the saw wire, the saw wire breaks during the stock retrieval. In this case, the workpiece must be completely removed from the defective wire web, the wire residues removed from the cutting gap by hand, and the wire web repaired again before the next cutting process. This is time-consuming and expensive.

Occasionally, the saw wire breaks during the cutting process due to saw wire overloading or material defects. The partially cut workpiece must then be removed from the defective wire web by resetting the feed device, removing the remaining wire from the cutting gap, repairing the wire web, threading the wire segment back into the existing cutting gap, and feeding the workpiece again to the cutting depth where the wire break occurred, so that the cutting process can be completed. In the case of wire EDM grinding, since the saw wire has sufficient play in the cutting gap due to the surrounding slurry film, the workpiece is effortlessly passed through and fed into the wire web without the saw wire getting stuck at a given cutting depth. In the case of wire EDM grinding, where the saw wire has no freedom of movement, the saw wire sticks during the workpiece feed and produces a cut.

Even if a diamond coating saw wire jams in an unforeseen manner during the workpiece feed after the wire has broken or when resetting the feed from the wire web during blank retrieval, the lack of freedom of movement in each case leads to additional material removal from the side walls that delimit the gap and thus to damage of the front and back sides of the slice concerned. This damage induces material stresses on the damaged surface, which, when the stresses on the front and back sides of the slice are not balanced with each other, which is usually not the case, lead to elastic deformation of the slice. This elastic deformation caused by the surface damage is superimposed on the plastic deformation and the plastic deformation cannot be determined individually by determining the slice shape by measurement after wire sawing and therefore cannot be eliminated selectively by appropriate measures. The latter is necessary because elastic deformation disappears when the damaged layer is removed in a subsequent material removal process, whereas plastic deformation remains if it is not eliminated by selective material removal.

US 2009/0223539 A1 describes a method for cleaning wafers for solar applications, for example, which are immersed in a cleaning bath and removed from a wire saw after the cutting process is completed, still suspended on a saw beam (sacrificial beam) via their adhesive joints. The cutting gap (kerf) is exposed to a rinsing fluid from a plurality of independent spray nozzles. At the point where the rinsing fluid is sprayed, the cutting gap in the water bath is widened, so that the cleaning action is increased. By moving the nozzles relative to the workpiece, all cutting gaps can be widened one after another, thus cleaning continuously. The method described does not help to avoid the consequences of stick-slip movements of the sawing line during blank retrieval.

JP 2006-66793 A describes a similar method in which a cut section is sprayed with a spray fluid after the cutting process has been completed and removed from the wire saw in order to clean the side surfaces with the aid of a spray nozzle.

US 2011/0168212 describes a similar method for cleaning thin, fragile solar wafers after sawing and removing the cut workpiece from the wire saw.

JP2004-106360 describes a method in which, after wire sawing and grinding of the workpiece and blank retrieval, a flushing fluid is fed through a channel present in the beam to clean the cutting gap.

The object of the present invention is to avoid the stick-slip motion of sawing wire and its adverse consequences.

The object of the present invention is achieved by a method for simultaneously cutting multiple slices from a workpiece by means of a wire saw, the method comprising: a slicing grinding process, wherein the workpiece is moved perpendicularly to its longitudinal axis towards a wire web of a sawing wire stretched between two wire rolls, the sawing wire is moved in the longitudinal direction of the sawing wire, wherein a cooling lubricant is supplied to the wire web, and wherein slices are generated between the wire segments of the wire web, which are fastened to the beam and have cutting gaps therebetween; and removing the beam and the slices from the wire web; The invention is characterized in that during the removal of the beam and the slice, the cutting gap is sprayed with a fluid by a spray device until the line segment leaves the cutting gap, wherein the fluid is supplied under high pressure through a nozzle fastened to a nozzle bracket so that the nozzle bracket moves in a swinging manner parallel to the longitudinal axis of the workpiece, wherein the fluid and the entrained air occasionally stimulate the vibration of the slice.

During the removal, the nozzles spray the fluid onto the cutting gap. During this period, the surrounding air is swirled and the slice is caused to vibrate via the Bernoulli effect. The nozzle holder performs an oscillating stroke movement parallel to the workpiece axis, which is why the fluid from at least one nozzle in the plane of the corresponding cutting gap occasionally encounters each cutting gap. In this way, the fluid penetrates deep into the cutting gap and the variation of the spray pressure caused by the oscillating movement gradually leads to a continuous periodic fanning of all the cutting gaps during the removal of the strip and the slice from the cutting gap.

The pressure at which the fluid is fed through the nozzle is preferably chosen in such a way that the exit velocity of the rinsing agent corresponds to the velocity at which the wire moves relative to the workpiece.

The nozzles are preferably part of a spray device, which in each case comprises at least one nozzle holder, which is arranged on the side of the wire roll of the wire web between the respective wire roll and the workpiece. The nozzle holder can perform a stroke movement parallel to the workpiece axis and is preferably arranged parallel to the rotation axis of the wire roll.

Particularly preferred are exactly two nozzle supports, with respect to which, viewed in the direction of the workpiece axis, new wires are arranged on the entry side of the workpiece and used wires are arranged on the exit side of the workpiece. The nozzles are preferably oriented in such a way that each nozzle generates a partial fluid flow which is tangentially to the wire web and is oriented in one of the planes in which the cutting gap extends. The amplitude of the oscillating movement which moves the respective nozzle support parallel to the longitudinal axis of the workpiece is preferably at least half the space between two adjacent nozzles. The total stroke corresponding to the double amplitude is therefore at least the space between two nozzles. In this way, it is ensured that after a certain period of oscillating movement, each nozzle covers all cutting gaps between it and the adjacent nozzles.

The number of nozzles per nozzle holder is preferably 10 to 50. As many nozzles as possible is particularly preferred. The upper limit of the number is determined only by the size of the nozzles. As a result, the stroke required for the oscillating movement of the nozzle holder is smaller and the covering of the cutting gap is carried out at shorter intervals.

During the cut-off grinding process, the workpiece is fed with the aid of a feed device. The wire rolls rotate in the same direction so that the wire segments describe a relative movement with the workpiece and during engagement with the workpiece, material removal occurs due to the feed movement.

At the end of the cutting and grinding process, the workpiece is completely cut into slices, and a plurality of parallel cutting gaps are formed between the slices, and the slices are retained by the beams.

Removing beams and slices from the cutting gap involves resetting the feed device while the line segment is moved longitudinally along the line in the presence of a cooling lubricant.

The workpiece is preferably a cylindrical rod composed of single-crystal semiconductor material.

The method preferably further comprises: during the cutting and grinding process, pivoting the workpiece about an axis parallel to the longitudinal axis of the workpiece, wherein the workpiece performs a plurality of pairs of pivoting motions, and a pair of pivoting motions comprises a first pivoting about a first angle at a first angular velocity and a second pivoting about a second angle at a second angular velocity. The first angular velocity and the second angular velocity and the first angle and the second angle of two pairs of the consecutive pairs of pivoting motions are preferably different.

The saw wire is preferably a hypereutectoid pearlite steel wire (piano wire) with a cutting tool fixed to its surface. The cutting tool is preferably diamond.

During the cut-off grinding process, the movement of the saw line in the longitudinal direction can occur in an inverted direction or in a non-inverted direction. In the inverted direction, during the movement of the saw line in the longitudinal direction, the saw line is moved by a plurality of pilger steps, wherein each pilger step includes a first movement of the saw line in a first longitudinal direction around a first length and a second movement of the saw line in a second longitudinal direction diametrically opposite to the first line longitudinal direction around a second length, and the first length is greater than the second length.

The cooling lubricant and the fluid are preferably made of water and contain liquid additives if necessary. They may all have the same composition or different compositions. The liquid additive is preferably a wetting agent, a corrosion inhibitor, a viscosity-modifying agent such as ethylene glycol and/or methyl cellulose, a defoaming agent or any mixture of these agents.

The procedure according to the invention is also preferably used to react appropriately to interruptions in the cutting and grinding process, in particular interruptions caused by the break of the sawing wire. It prevents the wire segments from sticking and grooves or elastic deformations from adversely affecting the slice quality during the removal of the workpiece after the wire break and during the reverse movement of the workpiece back to the position before the wire break.

The interruption of the cutting and grinding process occurs while the sawing line continues to move in the longitudinal direction and includes removing the workpiece from the cutting gap, returning the workpiece to the cutting gap, and continuing the cutting and grinding process. During the return of the workpiece, the fluid is sprayed into the cutting gap through the nozzle and the nozzle holder is moved parallel to the longitudinal axis of the workpiece.

During the cut-off grinding process, the movement of the saw line in the longitudinal direction preferably occurs at a speed that is at least ten times faster than the speed of the movement of the saw line in the longitudinal direction during the removal and return of the workpiece when the cut-off grinding process is interrupted.

The present invention will be described below with reference to the accompanying drawings using preferred exemplary implementations of a wire saw.

As shown in FIG1 , during wire sawing, the sawing wire 4 is guided helically around at least two wire rollers in the following manner: Two wire rollers 5 and 6 straddle a wire web 24 facing the workpiece 1, the wire web 24 consisting of mutually parallel wire segments. The wire rollers are in the shape of straight circular cylinders along mutually parallel oriented rotation axes 7 and 8, and the wire rollers can rotate around the rotation axes 7 and 8 in a direction 11. The side surfaces of the wire rollers are provided with a plurality of annular closed grooves 23 extending in a plane perpendicular to the rotation axes 7 and 8, which guide the sawing wire 4. Rotating the wire rollers in the same direction generates a relative movement between the wire segments and the workpiece. In this case, new saw wire is taken from a first stock (the so-called new wire reel) (direction 9) and used saw wire is fed into a second stock (the so-called used wire reel) (direction 10). The wire saw also has a feed device to which the workpiece 1 is fastened with the beam 2 via an adhesive joint 25 and which feeds the workpiece perpendicularly to the wire web (direction 3). When there is contact between the workpiece and the wire web, the relative movement and the presence of an abrasive cutting tool cause material to be removed from the workpiece. By continuous feeding, relative movement and supply of cutting tools, each wire segment of the wire web 24 forms a cutting gap 22 by continuously removing material from the workpiece. The side walls of the dicing gap 22 define the back side of one slice and the front side of the second slice 34 of a pair of adjacent wafers.

The cutting tool is a diamond 33, which is fixedly bonded into the surface of the wire 1. During the cut-off grinding process, a coolant 15 is fed into the wire web 24 via two nozzle holders 12, 13 on the left and right of the workpiece, which are respectively provided with nozzles 14, and the coolant itself does not contain abrasive cutting tools (hard substances). The cut-off grinding process ends when the entire wire web has completely passed through the workpiece and comes to rest in the beam 2. The slice 34 of the completely cut workpiece is then suspended on the half sliced-through beam like the teeth of a comb, connected to the beam 2 only via the adhesive joint 25.

The wire saw shown is provided with a left nozzle holder 16 and a right nozzle holder 17. The nozzle holders 16, 17 carry a plurality of nozzles 20 which spray a fluid 21 onto a cutting gap 22 in a workpiece 1. The axes 18 and 19 of the nozzle holders are arranged parallel to each other and parallel to the axes of rotation 7 and 8 of the wire rolls 5 and 6 of the stretching wire web 24 and perpendicular to the cutting gap 22 of the workpiece 1 or parallel to the longitudinal axis 26 of the workpiece 1. The nozzle holders perform oscillating movements 27 and 28 in the direction of their axes 18 and 19. By means of this periodic displacement, the flow of fluid 21 leaving the individual nozzles 20 covers the cutting gap 22 of the workpiece 1 at periodic intervals.

1 shows the nozzle holder 16 to the left of the workpiece 1, in other words, on the new wire inlet side, and the nozzle holder 17 to the right of the workpiece 1, in other words, on the used wire outlet side, and both are below the wire web 24, as seen from the direction of the feed device. In contrast, the nozzle holder can also be arranged above the wire web 24.

As already mentioned, the method according to the invention can also be carried out using a wire saw, in which the workpiece can be pivoted about an axis parallel to the longitudinal axis of the workpiece during the cutting and grinding process. During this oscillation, at any point in time, only the part of the entire wire segment that runs within the cutting gap is in material-removing contact with the workpiece. Viewed longitudinally along the wire, a gap is formed both before and after the momentary contact face between the saw wire and the workpiece that extends in the direction of feed of the workpiece. If the nozzle holder is arranged above the wire web, the fluid can reach particularly well between the saw wire and the workpiece. If the nozzle holder is arranged below the wire web, despite the oscillation, almost no fluid can enter between the saw wire and the workpiece. On the other hand, in this case, the cut part of the workpiece (then the wafer) protruding under the wire web is vibrated particularly effectively by the Bernoulli effect of the fluid flow, resulting in a cyclical expansion and reduction of the cutting gap width.

2(A) and (B) show details of the spray device including the nozzle holders 16 and 17 in a plan view (seen from the direction of the feed device), these details relating to the left nozzle holder 16 and a portion of the workpiece 1 with the cutting gap 22 and the longitudinal axis 26 of the workpiece.

FIG. 2(A) shows a nozzle holder 16 with an axis 18 parallel to the longitudinal axis 26 of the workpiece at the start of a swaying movement 27 parallel to the axis 18. There are nozzles 31, from which in each case a portion of the flow of the fluid 21 flows precisely in the plane of the cutting gap 22, as a result of which the fluid 21 is forced deep into the cutting gap 22. In the process, a pair of adjacent slices 34 that divide the cutting gap 22 in the direction of movement 29 are elastically pressed away from the cutting gap, as a result of which the cutting gap is elastically widened to a widened slicing gap 30. Furthermore, there are nozzles 32, without which the flow of fluid 21 flows in the plane of the cutting gap 22, and therefore these nozzles do not elastically widen the cutting gap. The flow of fluid 21 entrains air 35 from the environment by means of momentum exchange.

When the left nozzle support 16 has performed the oscillating movement 27 in the direction of the axis 18, it reaches the position shown in FIG. 2 (B) at the other end of its oscillating movement. The nozzles 31 are in different positions and widen the other cutting gaps to the cutting gap in the arrangement according to FIG. 2 (A), and some of the flow from these nozzles presses the fluid into the cutting gap and thus widens it. The amplitude of the oscillating movement 27 is at least equal to the value of the space between two adjacent nozzles.

During the oscillating motion 27, the flow of fluid 21 (fluid is incompressible) and the air 35 entrained by the flow (air/gas is compressible) are diffused outside the slice 34 and the cutting gap 22. Since they flow around the slice and the cutting gap in different planes during the oscillating motion, the slice 34 is stimulated by the dynamic pressure changes of the air entrained by the flow to produce vibrations (Bernoulli effect). In other words, it causes elastic deflection of the slice and a periodic widening and gradual narrowing of the cutting gap.

The research on which the present invention is based, aimed at avoiding stick-slipping of the saw line during blank retrieval and during repositioning of the workpiece after an interruption in the cut-off grinding process, showed that in order to reduce the friction of the saw line in a narrow cutting gap, it is necessary to stimulate vibrations in the slice. Widening the cutting gap by forcibly pressing in a fluid when changing the cutting gap and the cleaning effect associated therewith also occur slowly as a single measure. It is therefore not possible to prevent grooves or strain-induced warpage of the saw line during blank retrieval or during repositioning of the workpiece after an interruption.

Only the stimulation of vibrations in the slice by means of a fluid flow with entrained air via the Bernoulli effect has proven to be a suitable means to achieve this goal.

1: Workpiece 2: Beam 3: Feed direction 4: Saw line 5: Left wire roller 6: Right wire roller 7: Rotation axis 8: Rotation axis 9: Wire supply direction 10: Wire removal direction 11: Wire roller rotation direction 12: Bracket 13: Bracket 14: Nozzle 15: Cooling lubricant 16: Left nozzle bracket 17: Right nozzle bracket 18: Axis of left nozzle bracket 19: Axis of right nozzle bracket 20: Nozzle 21: Fluid 22: Cutting gap 23: Groove 24: Wire mesh 25: Bonding joint 26: Longitudinal axis of workpiece 27: Oscillating motion 28: Oscillating motion 29: Direction of motion 30: Widened cutting gap 31: Nozzle 32: Nozzle 33: Diamond 34: Slice 35: Entrained air

FIG. 1 shows features of a wire saw and a workpiece, which is helpful for understanding the present invention. FIG. 2 (A) and (B) show details of a spraying device suitable for carrying out the method according to the present invention.

1: Workpiece

2: Beam

3: Feed direction

4: Saw cutting line

5:Left wire roller

6: Right wire roller

7: Rotation axis

8: Rotation axis

9: Line supply direction

10: Line removal direction

11: Rotation direction of the wire roller

12: Bracket

13: Bracket

14: Nozzle

15: Cooling lubricant

16: Left nozzle bracket

17: Right nozzle bracket

18: Axis of the left nozzle bracket

19: Axis of the right nozzle bracket

20: Nozzle

21: Fluid

22: Cutting gap

23: Groove

24:Wire Network

25: Bonding joints

26: Longitudinal axis of the workpiece

27: Swinging movement

28: Swinging movement

33: Diamond

34: Slice

Claims (12)

A method for simultaneously cutting a plurality of slices from a workpiece by means of a wire saw, comprising: a slicing grinding process, wherein the workpiece is moved perpendicularly to its longitudinal axis towards a wire web of a sawing wire stretched between two wire rolls, the sawing wire is moved in the longitudinal direction of the sawing wire, wherein a cooling lubricant is supplied to the wire web, and wherein slices are generated between wire sections of the wire web which are fastened to a beam and have slicing gaps therebetween; and removing the beam and the slices from the wire web, wherein the cutting gap is sprayed with a fluid by a spray device during the removal of the beam and the cutting until the line segment leaves the cutting gap, wherein the fluid is supplied under high pressure through a nozzle fastened to a nozzle bracket, the nozzle bracket being moved in an oscillating manner parallel to the longitudinal axis of the workpiece, wherein the fluid and the entrained air occasionally stimulate vibrations of the cutting piece. A method as described in claim 1, wherein the amplitude of the swinging motion is equal to or greater than the total space between two adjacent nozzles. A method as claimed in claim 1 or 2, wherein the cutting and grinding process is interrupted while the saw line continues to move in the longitudinal direction, comprising: removing the workpiece from the cutting gap; returning the workpiece to the cutting gap; and continuing the cutting and grinding process, wherein, during the return of the workpiece, a fluid is sprayed into the cutting gap through the nozzle and the nozzle support is moved parallel to the longitudinal axis of the workpiece. A method as described in claim 1 or 2, wherein during the cutting and grinding process, the workpiece is pivoted about an axis parallel to the longitudinal axis of the workpiece, wherein the workpiece performs a plurality of pairs of pivoting motions, and a pair of pivoting motions includes a first pivoting about a first angle at a first angular velocity and a second pivoting about a second angle at a second angular velocity. A method as described in claim 4, wherein the first angular velocity and the second angular velocity and the first angle and the second angle of two pairs in the continuous pivoting motion are different. A method as described in claim 1 or 2, wherein the cooling lubricant includes water and a first liquid additive, and the fluid includes water and a second liquid additive. The method of claim 6, wherein the first liquid additive and the second liquid additive are the same and include a wetting agent or a corrosion inhibitor or a viscosity-influencing agent, a defoaming agent or a mixture thereof. The method as claimed in claim 1 or 2, wherein the saw wire is composed of a hypereutectoid pearlitic steel wire with diamond fixed on the surface as a cutting means. A method as described in claim 1 or 2, wherein the workpiece is a cylindrical rod of single crystal semiconductor material. A method as described in claim 3, wherein the saw line moves longitudinally at a speed during the cutting and grinding process that is at least ten times faster than the speed at which the saw line moves longitudinally during the removal and return of the workpiece. A method as described in claim 1 or 2, wherein the sawing line moves in a longitudinal direction without reversing the direction. A method as described in claim 1 or 2, wherein, in the case of an inverted direction, the sawing line moves in a longitudinal direction, wherein the sawing line is moved by a plurality of pilger steps, each pilger step comprising a first movement of the sawing line along a first longitudinal direction around a first length and a second movement of the sawing line along a second longitudinal direction completely opposite to the first line longitudinal direction around a second length, and the first length is greater than the second length.