JP2010212467A - Method of slicing semiconductor ingot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of slicing a semiconductor ingot suppressing a warpage of a sliced wafer to enhance the planarity of a wafer surface. <P>SOLUTION: The method includes: moving in a horizontal direction, a wire 16 horizontally expanded between a pair of rollers 11, 12 provided so that the central axes of the rollers become parallel to each other by the rotation of the rollers; positioning a single semiconductor ingot over the wire between the plumb lines of the pair of rollers each passing through each central axis of the rollers in a first position in which the central axis of the ingot becomes parallel to each central axis of the pair of rollers; and moving the ingot downwards in the plumb line from the first position to a second position crossing the wire moving in a horizontal direction to slice the ingot 13. When slicing an ingot having a small diameter, when displacing the ingot as approaching to any one of the pair of rollers relative to the plumb line passing through the intermediate position between the pair of rollers in the wire and moving the ingot downwards, the distance X between the plumb line at the outer circumference of the roller to which the ingot has been brought closer and the plumb line at the outer circumference of the ingot is 1 to 45 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for slicing a semiconductor ingot using a wire saw device. More specifically, the present invention relates to a method of simultaneously slicing a plurality of wafers from a single semiconductor ingot.

  Conventionally, as a method for slicing this type of semiconductor ingot, a method for slicing a semiconductor ingot that obtains a wafer by cutting the semiconductor ingot into slices with a wire saw has been disclosed (for example, see Patent Document 1). In this method for cutting a semiconductor ingot, the semiconductor ingot is provided so as to be movable in the direction of the central axis, and the amount of displacement in the direction of the central axis is cut while being controlled in accordance with a change in the cutting position of the semiconductor ingot. Further, the warp tendency of the wafer due to the cutting of the wire saw is obtained in advance, and the displacement amount in the central axis direction of the semiconductor ingot is set so as to eliminate this warp tendency. In the semiconductor ingot cutting method configured as described above, a semiconductor ingot cutting device using a wire saw is used, the cutting surface can be easily controlled, and the control only controls the displacement of the workpiece holding plate. The cutting device is not complicated.

JP-A-9-286021 (Claim 1, paragraph [0012], FIG. 6)

  In the conventional method for cutting a semiconductor ingot disclosed in Patent Document 1, as shown in FIG. 5, between a pair of main rollers 1 and 2 and a single sub-roller 4 whose central axes are arranged in parallel to each other, as shown in FIG. The wire 6 is stretched horizontally, and the roller 6 moves in the horizontal direction by the rotation of the rollers 1, 2, and the vertical line passes through the intermediate position between the pair of main rollers 1 and 2 above the wire 6. In a state where the central axes of the single ingots 3 intersect with each other, the ingot 3 is lowered in the vertical direction and sliced to obtain a plurality of wafers simultaneously. The distance between the pair of main rollers 1 and 2 is desirably as narrow as possible on the condition that the ingot 3 can pass between the pair of main rollers 1 and 2, whereby the bending amount of the wire 6 when the ingot 3 is sliced. Can be suppressed.

  However, when slicing a plurality of types of ingots 3 having different diameters, if the wire saw device 5 is manufactured or purchased for each type, the manufacturing cost of the device 5 or the purchase cost of the device 5 increases. In order to eliminate this point, if a single wire saw device 5 is manufactured or purchased in accordance with the ingot 3 having the largest diameter among the plurality of types of ingots 3, a plurality of types of ingots 3 can be obtained using the single wire saw device 5. Can be sliced. However, in this case, when the ingot 3 having a diameter smaller than the maximum diameter of the slicable ingot is sliced, the amount of bending of the wire 6 increases, and the warp of the sliced wafer tends to increase.

  An object of the present invention is to provide a semiconductor ingot slicing method that can suppress warping of a sliced wafer and improve the flatness of the wafer surface.

  According to a first aspect of the present invention, a wire is horizontally stretched between a pair of rollers whose central axes are arranged in parallel to each other and moves in the horizontal direction by the rotation of the roller, and above or below the wire. A single semiconductor ingot is arranged between the vertical lines passing through the central axes of the pair of rollers at a first position where the central axis is parallel to the central axes of the pair of rollers, and the ingot is vertically moved from the first position. When slicing an ingot having a diameter smaller than the maximum diameter of a slicable ingot in a method for slicing an ingot by slicing the ingot by lowering or raising in a direction to reach a second position across a wire moving in a horizontal direction In addition, the ingot is not oriented in the direction of approaching one of the pair of rollers with respect to a vertical line passing through the intermediate position of the pair of rollers in the wire. And, and when lowered or raised ingots, the distance between the vertical tangent at the outer circumferential surface of the vertical tangent and the ingot in the outer peripheral surface of the close side of the roller is characterized in that it is a 1～45Mm.

  A second aspect of the present invention is an invention based on the first aspect, and when slicing an ingot having a maximum slicing diameter, the central axis of the ingot intersects a vertical line passing through an intermediate position between a pair of rollers. The ingot is held by the holding member so that the holding member is connected to the elevating means by the connecting member, and then the ingot is lowered or raised by the elevating means, thereby slicing the ingot having the maximum slicing diameter, and When slicing an ingot having a diameter smaller than the maximum diameter of the slicable ingot, a jig is interposed between the holding member and the connecting member, so that the ingot is paired with respect to a vertical line passing through an intermediate position between the pair of rollers. Shift in the direction approaching one of the rollers, and lower or raise the ingot with the lifting means to reduce the diameter Characterized in that an ingot is sliced.

  A third aspect of the present invention is an invention based on the first aspect, further comprising a connecting member for connecting the holding member to the elevating means extending in the longitudinal direction of the wire, and slicing the ingot with the maximum diameter that can be sliced. When the ingot is held by the holding member so that the central axis of the ingot intersects the vertical line passing through the intermediate position between the pair of rollers, the ingot is lowered or raised by the lifting means, thereby allowing the maximum slicing diameter. When slicing an ingot having a diameter smaller than the maximum diameter of the slicable ingot, mounting the holding member at a position different from the mounting position of the holding member when slicing the ingot having the maximum slicing diameter. By setting the position, a pair of ingots are aligned with respect to a vertical line passing through the intermediate position of the pair of rollers. The ingots falling or is raised by lifting means is shifted in a direction close to one of rollers over La, characterized by slicing the diameter of the ingot.

  In the method according to the first aspect of the present invention, when the ingot is lowered or raised by rotating the pair of rollers while the ingot is positioned at the first position close to one of the rollers, the ingot is pressed against the wire on which the ingot runs. Is done. Since the amount of bending of the wire at this time is smaller than the amount of bending of the wire when the central axis of the ingot intersects the vertical line passing through the intermediate position of the pair of rollers, the warping of the sliced wafer can be suppressed. As a result, the flatness of the sliced wafer surface can be improved.

  In the method according to the second aspect of the present invention, only the holding means is attached to the connecting member via a jig, and the ingot is placed on either one of the pair of rollers with respect to a vertical line passing through the intermediate position of the pair of rollers. Therefore, the warpage of the wafer sliced from the small-diameter ingot can be suppressed by adding a few parts.

  In the method according to the third aspect of the present invention, the jig is not necessary, so that the number of parts can be reduced as compared with the method according to the second aspect, and the number of assembling steps to the lifting means of the ingot can be reduced.

It is a principal part block diagram of the wire saw apparatus used for the slicing method of the semiconductor ingot of 1st Embodiment of this invention. It is a perspective view of the wire saw apparatus used for the slicing method of the semiconductor ingot. It is a principal part block diagram of the wire saw apparatus used for the slice method of the semiconductor ingot of 2nd Embodiment of this invention. It is a figure which shows the distribution state of the curvature of the wafer after the slice of Example 1 and Comparative Example 1. FIG. It is a principal part block diagram of the wire saw apparatus used for the slice method of the conventional semiconductor ingot.

Next, an embodiment for carrying out the present invention will be described with reference to the drawings.
<First Embodiment>
As shown in FIGS. 1 and 2, a wire saw device 10 for slicing a silicon single crystal ingot 13 includes a pair of main rollers 11, 12 having central axes parallel to each other and disposed in the same horizontal plane. A single sub-roller 14 provided below the main rollers 11 and 12 and at an intermediate position between the pair of main rollers 11 and 12, and wound around the pair of main rollers 11 and 12 and the single sub-roller 14. The wire 16 provided, the holding means 17 which hold | maintains the ingot 13, and the raising / lowering means 18 which raises / lowers this holding means 17 are provided. In this specification, the left main roller 11 of the pair of main rollers 11 and 12 is a first main roller, and the right main roller 12 is a second main roller. The outer peripheral surfaces of the first and second main rollers 11 and 12 and the single sub-roller 14 are spaced apart in the axial direction of each of the rollers 11, 12 and 14, that is, by the thickness of the wafer to be sliced. A plurality of ring grooves (not shown) extending in the circumferential direction are formed at intervals in the axial direction of the rollers 11, 12, and 14. The wire 16 is one long piece wound around the feeding bobbin 21 (FIG. 2), and the wire 16 fed from the feeding bobbin 21 is connected to the first and second main rollers 11 and 12 in a single manner. These rollers 11, 12, and 14 have a substantially inverted triangular shape and are wound in a spiral manner so as to be accommodated in order from each ring groove on one end side to each ring groove on the other end side of the sub roller 14. After being installed, it is configured to be wound on a winding bobbin 22 (FIG. 2).

  The holding means 17 includes a slicing base 17a bonded to the ingot 13 and a work plate 17b that holds the slicing base 17a. The slicing base 17a is formed of the same material as the ingot 13, or glass, ceramic, carbon, resin, or the like, but carbon, resin, or the like is often used in consideration of cost and ease of molding. As the adhesive, epoxy resin, thermoplastic wax or the like is used, and the work plate 17b is mainly formed of SUS. Further, the work plate 17b of the holding member 17 is connected to the lifting means 18 via a connecting member 23 extending in the horizontal direction. The elevating means 18 is provided so as to extend in the vertical direction, and is configured to be able to raise and lower the ingot 13 via the connecting member 23 and the holding means 17.

  Of the wire 16 wound and stretched between the first and second main rollers 11 and 12 and the single sub-roller 14, it was stretched horizontally between the first and second main rollers 11 and 12. The wire 16 is configured to move in the horizontal direction by the rotation of the first and second main rollers 11 and 12 and the single sub roller 14. Further, the ingot 13 is horizontally stretched between the first and second main rollers 11 and 12 by bonding the ingot 13 to the slicing base 17a in which the connecting member 23 and the work plate 17b are connected to the lifting means 18. The central axis of the ingot 13 is above the central axis of the first and second main rollers 11 and 12 between the vertical lines passing through the central axes of the first and second main rollers 11 and 12 above the formed wire 16. The first position is parallel to the first position. Further, the ingot 13 is configured to be sliced by lowering the ingot 13 vertically from the first position to reach the second position crossing the wire 16 moving in the horizontal direction.

  The characteristic configuration of the present embodiment is that when the ingot 13 having a diameter smaller than the maximum diameter of the ingot that can be sliced by the wire saw device 10 is sliced, the ingot 13 is used as the first and second main rollers 11 and 12 in the wire 16. It is comprised so that it may shift in the direction which approaches the 1st main roller 11 with respect to the perpendicular line which passes the intermediate position. Specifically, a jig 24 is interposed between the work plate 17 b of the holding member 17 and the connecting member 23, and thereby the ingot 13 is configured to be shifted in a direction approaching the first main roller 11. The amount of deviation of the ingot 13 toward the first main roller 11 is such that when the ingot 13 is lowered, the distance X between the lead direct wire on the outer peripheral surface of the first main roller 11 and the lead direct wire on the outer peripheral surface of the ingot 13 is It is set to 1 to 45 mm, preferably 5 to 40 mm. Here, the distance X is limited to a range of 1 to 45 mm. If the distance X is less than 1 mm, the ingot 13 may come into contact with the first main roller 11. This is because the warpage of the wafer sliced by the apparatus 10 becomes large.

  In this specification, it is described that the ingot 13 is arranged so that the central axis thereof is parallel to the central axes of the first and second main rollers 11, 12. However, the above “parallel” refers to the crystal of the ingot 13. It is used to include the case of slightly inclining, for example, 0.2 degrees with respect to the central axis of the main rollers 11 and 12 so as to match the surface orientation inclination angle. When slicing an ingot having the maximum diameter that can be sliced by the wire saw device 10, the holding means is attached to the tip of the connecting member without using a jig, so that the central axis of the ingot is the first and second main rollers. 11 and 12 intersect with a vertical line passing through an intermediate position. By lowering the ingot by the lifting / lowering means 18 from this state, the ingot having the maximum slicing diameter is sliced. Here, the slicable maximum diameter ingot refers to the maximum diameter ingot that can be sliced by the wire saw device 10 shown in FIG. Specifically, the outer peripheral surface of the first main roller 11 when the ingot 13 is lowered in a state where the central axis of the ingot intersects a vertical line passing through an intermediate position between the first and second main rollers 11 and 12. The distance X between the lead direct wire and the lead direct wire on the outer peripheral surface of the ingot 13 is an ingot having a diameter of 1 to 45 mm, preferably 5 to 40 mm.

  On the other hand, although not shown, a nozzle protrudes toward the wire 16 stretched between the first and second main rollers 11 and 12. This nozzle is connected to a tank through a pump, and slurry containing a mixture of SiC abrasive grains and oil is stored in this tank. The slurry is discharged from the nozzle toward the wire 16 and adheres to the wire 16, and the wire 16 to which the slurry adheres travels in contact with the ingot 13 at a predetermined pressure, and the SiC abrasive grains in the slurry are ingot 13. The ingot 13 is configured to be sliced by shaving.

  A method of slicing the ingot 13 using the wire saw device 10 configured as described above will be described. For example, when slicing, for example, an ingot 13 having a diameter of 200 mm using the wire saw device 10 having a maximum slicing ingot of 300 mm, the ingot 13 is first bonded to the slicing base 17a using an adhesive such as epoxy resin. The slicing base 17a is connected to the lifting / lowering means 18 through the work plate 17b, the jig 24 and the connecting member 23. As a result, the ingot 13 is arranged at the first position close to the first main roller 11. Next, when the first and second main rollers 11 and 12 and the single sub-roller 14 have the same peripheral speed and are rotated in the same direction, the wire 16 travels at a predetermined speed and is fed from the feeding bobbin 21. After traveling through the outer peripheral surfaces of the rollers 11, 12, and 14, the rollers are wound on the winding bobbin 22. Further, when the ingot 13 is lowered by the elevating means 18 while discharging the slurry from the nozzle, the first and second wires 16 wound between the first and second main rollers 11 and 12 and the single sub-roller 14 are Since the wire 16 stretched horizontally between the second main rollers 11 and 12 moves in the horizontal direction by the rotation of the first and second main rollers 11 and 12 and the single sub roller 13, the ingot 13 The vehicle runs while contacting with a predetermined pressure the wire 16 stretched horizontally and to which the slurry is adhered. Thereby, since the SiC abrasive grains in the slurry scrape the ingot 13, the ingot 13 is sliced. At this time, the amount of bending of the horizontally stretched wire 16 is the amount of bending of the wire 16 when the central axis of the ingot 13 intersects the vertical line passing through the intermediate position between the first and second main rollers 11 and 12. Since it is smaller, the warpage of the sliced wafer can be suppressed. As a result, the flatness of the sliced wafer surface can be improved.

  Note that an ingot having a diameter of 150 mm, an ingot having a diameter of 125 mm, or the like may be sliced by using a wire saw device having a maximum diameter of 300 mm that can be sliced. Alternatively, a wire saw having a maximum diameter of 400 mm that can be sliced may be used to slice an ingot having a diameter of 300 mm, an ingot having a diameter of 200 mm, an ingot having a diameter of 150 mm, an ingot having a diameter of 125 mm, or the like.

<Second Embodiment>
FIG. 3 shows a second embodiment of the present invention. 3, the same reference numerals as those in FIG. 1 denote the same components. In this embodiment, a connecting member 53 that connects the holding member 17 to the elevating means 18 is provided extending in the longitudinal direction of the wire 16, that is, the connecting member 53 is formed longer than the connecting member of the first embodiment, The jig of the first embodiment is not used. Specifically, when slicing the ingot with the maximum diameter that can be sliced, the ingot is held by the holding member 17 so that the vertical axis passing through the intermediate position between the first and second main rollers 11 and 12 intersects the central axis of the ingot. Retained. From this state, the ingot having the maximum diameter that can be sliced is sliced by lowering the ingot by the elevating means 18. On the other hand, when slicing the ingot 13 having a diameter smaller than the maximum diameter of the ingot that can be sliced, the holding member is held at a position different from the attachment position of the holding member 17 when the ingot having the maximum diameter that can be sliced is sliced. 17, that is, by attaching the holding member 17 to the distal end portion of the connecting member 53, the ingot 13 is moved to the vertical line passing through the intermediate position between the first and second main rollers 11, 12. 1 It is comprised so that it may shift in the direction approaching the main roller 11. From this state, the ingot 13 with a small diameter is sliced by lowering the ingot by the lifting means 18. The configuration other than the above is the same as that of the first embodiment.

  When slicing the ingot 13 using the wire saw device 50 configured as described above, the jig of the first embodiment is not necessary, so that the number of parts can be reduced as compared with the first embodiment, and the ingot 13 can be reduced. The assembly man-hour to the lifting / lowering means 18 can be reduced. Since operations other than those described above are the same as those in the first embodiment, repeated description will be omitted.

  In the first and second embodiments, a silicon single crystal ingot is used as the semiconductor ingot. However, a semiconductor ingot such as a GaAs single crystal ingot, an InP single crystal ingot, a ZnS single crystal ingot, or a ZnSe single crystal ingot may be used. . In the first and second embodiments, the pair of main rollers is disposed above the sub rollers, and the ingot disposed above the wire stretched between the pair of main rollers is lowered in the vertical direction to slice. However, a pair of main rollers may be arranged below the sub-roller, and an ingot arranged below the wire stretched between the pair of main rollers may be raised in the vertical direction and sliced. Furthermore, in the first and second embodiments, three rollers (a pair of main rollers and a single sub roller) are used, but two rollers (a pair of main rollers only) may be used. Alternatively, four rollers (a pair of main rollers and a pair of sub rollers) may be used, or five or more rollers (a pair of main rollers and three or more sub rollers) may be used.

Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>
As shown in FIGS. 1 and 2, an ingot 13 having a diameter of 200 mm was sliced using a wire saw device 10 capable of slicing a silicon single crystal ingot having a maximum diameter of 300 mm. The diameters of the first and second main rollers 11 and 12 of the wire saw device 10 were 165 mm, and the diameter of the sub roller 14 was 165 mm. The distance L between the central axes of the first and second main rollers 11 and 12 was 540 mm. Further, when the ingot 13 is shifted in the direction approaching the first main roller 11 with respect to the vertical line passing through the intermediate position between the first and second main rollers 11 and 12, and the ingot 13 is lowered, the ingot 13 1 The distance between the lead direct wire on the outer peripheral surface of the main roller 11 and the lead direct wire on the outer peripheral surface of the ingot 13 was set to 40 mm.

  On the other hand, after the ingot 13 having a diameter of 200 mm is bonded to the slicing base 17a using an adhesive such as epoxy resin, the slicing base 17a is connected to the lifting / lowering means 18 via the work plate 17b, the jig 24 and the connecting member 23. did. As a result, the ingot 13 is disposed at the first position close to the first main roller 11. Next, the first and second main rollers 11 and 12 and the single sub-roller 14 were rotated in the same direction at the same peripheral speed, and the wire 16 was run at a speed of 600 m / min. Further, the ingot 13 was lowered by the lifting means 18 at a speed of 0.5 mm / min. Further, a slurry in which SiC abrasive grains and oil were mixed was supplied to the wire 16. Thus, the ingot 13 was sliced using the wire saw apparatus 10, and 250-270 silicon wafers were produced simultaneously. By slicing the ingot 13 by the wire saw device 10 ten times, a total of 2612 wafers were produced.

<Comparative Example 1>
The ingot was sliced in the same manner as in Example 1 except that the ingot was held by the holding member so that the central axis of the ingot crossed the vertical line passing through the intermediate position between the first and second main rollers. However, ingot slicing by a wire saw device was repeated 12 times to produce a total of 3010 wafers.

<Comparative test 1 and evaluation>
The warpage of each wafer sliced by the methods of Example 1 and Comparative Example 1 was measured by a flatness measuring device manufactured by ADE. The result (warp distribution) is shown in FIG. The warp distribution in FIG. 4 shows the warp distribution at the warp value. This warp value is a value represented by the difference between the maximum displacement and the minimum displacement from the three-point reference surface or the best fit reference surface to the center surface in the wafer thickness direction on the back surface of the wafer that is not attracted and fixed. Here, the warp distribution in FIG. 4 is expressed by a warp value because a warp value reflecting the warp distribution of the entire wafer is generally used as a specification of the wafer warp.

  As is apparent from FIG. 4, the average warp value of the wafer in Comparative Example 1 was as large as 8.89 μm, whereas the average warp value of the wafer in Example 1 was 7.77 μm. It has become smaller. This is considered due to the fact that the amount of bending of the wire of Example 1 was smaller than the amount of bending of the wire of Comparative Example 1. In Comparative Example 1, the difference δ between the maximum value and the minimum value of the warp value was about 20 μm, whereas in Example 1, the difference δ between the maximum value and the minimum value of the warp value was about 14 μm.

DESCRIPTION OF SYMBOLS 10,50 Wire saw apparatus 11 1st main roller 12 2nd main roller 13 Silicon single crystal ingot (semiconductor ingot)
16 Wire 17 Holding means 18 Lifting means 23, 53 Connecting member 24 Jig

Claims (3)

A wire is horizontally stretched between a pair of rollers whose central axes are arranged in parallel to each other and moves in the horizontal direction by the rotation of the roller. A single semiconductor ingot is arranged between the vertical lines passing through the central axis at a first position where the central axis is parallel to the central axes of the pair of rollers, and the ingot is lowered vertically from the first position. Or a method for slicing a semiconductor ingot, wherein the ingot is sliced by reaching a second position across the wire that is raised and moved horizontally.
When slicing an ingot having a diameter smaller than the maximum diameter of the slicable ingot, a direction in which the ingot approaches one of the pair of rollers with respect to a vertical line passing through an intermediate position of the pair of rollers in the wire And when the ingot is lowered or raised, the distance between the lead direct wire on the outer peripheral surface of the roller on the close side and the lead direct wire on the outer peripheral surface of the ingot is 1 to 45 mm. A method for slicing a semiconductor ingot. When slicing the ingot with the maximum diameter that can be sliced, the ingot is held by the holding member so that the central axis of the ingot intersects the vertical line passing through the intermediate position of the pair of rollers, and the holding member is moved up and down by the connecting member. After connecting to a means, the ingot of the maximum diameter that can be sliced is sliced by lowering or raising the ingot with the lifting means,
When slicing an ingot having a diameter smaller than the maximum diameter of the slicable ingot, a jig is interposed between the holding member and the connecting member, so that the ingot passes vertically between the pair of rollers. 2. The method for slicing a semiconductor ingot according to claim 1, wherein the small-diameter ingot is sliced by moving the ingot downward or upward by the elevating means while shifting in a direction approaching one of the pair of rollers with respect to a line. . A connecting member for connecting the holding member to the elevating means is provided extending in the longitudinal direction of the wire,
When slicing an ingot with the maximum diameter that can be sliced, the ingot is held by a holding member so that the central axis of the ingot intersects a vertical line passing through an intermediate position between a pair of rollers, and then the ingot is moved by the lifting means. Slicing the ingot of the maximum diameter that can be sliced by lowering or raising;
When slicing an ingot having a diameter smaller than the maximum diameter of the slicable ingot, the mounting position of the holding member is set at a position different from the mounting position of the holding member when slicing the ingot having the maximum slicing diameter. By shifting the ingot in a direction approaching one of the rollers of the pair of rollers with respect to a vertical line passing through an intermediate position of the pair of rollers, the ingot is lowered or raised by the lifting means, The method for slicing a semiconductor ingot according to claim 1, wherein a small-diameter ingot is sliced.

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