JP4411837B2 - Semiconductor substrate manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor substrate manufacturing method and manufacturing apparatus for processing a semiconductor substrate serving as a substrate for a semiconductor element or an integrated circuit from an ingot.
[0002]
[Prior art]
As is well known, in manufacturing a semiconductor substrate of a silicon wafer, CZ method (Czochralski method, pulling method), MCZ (Magnetic Field Applied CZ method), or FZ method (Floating Zone method, floating zone purification method) First, an ingot is generated by such a method. The ingot is subjected to grinding after crystal evaluation. In such grinding, for example, after grinding into a cylindrical shape having a predetermined diameter (wafer diameter) on the outer periphery of the ingot, a reference mark (notch surface) indicating a crystal orientation called an orientation flat or notch is formed on the outer periphery of the ingot. ) Is formed. Such fiducial marks are usually formed by subjecting a part of the peripheral surface of the ingot ground to the cylindrical shape to surface grinding. Here, FIGS. 10 and 11 show an example of such a grinding method and an apparatus used therefor.
[0003]
In the grinding to the above cylindrical shape, usually, as shown in FIG. 10, the ingot 100 is mounted on the rotary holder 102 via the pedestal 101 and a rotational motion is applied. And this ingot 100 is ground so that the outer periphery may become a predetermined diameter shown by a two-dot chain line in FIG. Incidentally, FIG. 10 illustrates a grinding mode in the case where grinding is performed with an inclination of a predetermined angle with respect to the longitudinal direction of the ingot 100.
[0004]
Then, when the grinding of the ingot 100 into the cylindrical shape is completed, the operation (rotation) of the rotary holder 102 to which the ingot 100 is attached is stopped. Thereafter, as shown in FIG. 11, the grindstone 103 is maintained in rotation so as to form the reference mark, here the orientation flat 104 (hereinafter, abbreviated as orientation flat) on a part of the peripheral surface of the ingot 100 in a stationary state. In this state, it is moved in the horizontal direction in the figure.
[0005]
The ingot in which the orientation flat 104 is surface ground in this manner is then bonded and fixed to an appropriate support base with the orientation flat 104 as a reference, and sliced by a device such as a blade such as an outer peripheral blade or an inner peripheral blade, or a wire saw, It is taken out as a thin disk-like (wafer-like) semiconductor substrate.
[0006]
[Problems to be solved by the invention]
In recent years, silicon carbide has attracted attention as a material for the semiconductor substrate in terms of high heat resistance, high breakdown voltage, and high power characteristics. However, as is well known, this silicon carbide is a very hard material, so that a great amount of processing time is required for manufacturing the semiconductor substrate as described above. At this time, if the ingot made of silicon carbide has a large diameter or is long, the processing time is further extended.
[0007]
On the other hand, when mechanical grinding and slicing as described above are performed on an ingot made of silicon carbide, the surface is likely to be chipped, cracked, cracked or the like because the material is hard. Furthermore, if such a crack progresses to the inside of the ingot, serious damage will be caused to the ingot itself.
[0008]
For example, as illustrated in FIG. 10 above, when grinding into a cylindrical shape with an inclination of a predetermined angle, the surface to be cut out with respect to the longitudinal direction of the ingot 100 is not vertical, but the ingot 100 or the grindstone 103. Will be processed by inclining by a predetermined angle. At this time, a load is intermittently applied to the surface of the ingot 100 until the predetermined diameter is reached, and the occurrence of cracks and the like is also likely to occur.
[0009]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor substrate manufacturing method capable of stably manufacturing a high-quality semiconductor substrate regardless of the hardness of a material used as a semiconductor ingot. And a manufacturing apparatus used in the manufacturing method.
[0010]
[Means for Solving the Problems]
  In order to achieve such an object, a method of manufacturing a semiconductor substrate according to claim 1 or claim4In the semiconductor substrate manufacturing apparatus described inSilicon carbideUsed for ingot crystal growthThe crystal orientation is knownSeed crystalofSolidSurfaceFirst reference plane parallel to the same crystalofSolidSurfaceAnd a second reference plane orthogonal toMade of conductive materialpedestalThese first and second reference planesWhen,TheSilicon carbideIngotAssociated with the crystal orientation of theIn the state, the first and second reference planes of the pedestal are used as a referenceWire dischargeBy processingTogether with the pedestal, silicon carbideingot, A substantially cylindrical shape, a substantially cylindrical shape including a fixed reference when slicing the ingot into a wafer shape, and a substantially cylindrical shape including a notch surface similar to an orientation flat shape or a notch shape as a final wafer. OneofIn shapeIt was decided to cut out.
[0011]
  For this reason,Wire dischargeThe positional relationship with the processing equipment,Silicon carbideThe positional relationship between the ingot and the machining apparatus is always properly maintained, and the machining accuracy is naturally maintained high. Also,Silicon carbideCutting out the ingotWire dischargeBy performing the processing, the serious damage described above on the ingot is eliminated. That is, appropriate and stable cutting is performed regardless of the hardness of the semiconductor ingot.
  Also,Silicon carbideThe ingot seed crystal is fixed to a plane parallel to the first reference plane of the pedestal,Silicon carbideThe ingot itself is crystal-grown based on the first reference surface of the pedestal. Moreover, the first reference surface of the pedestal is the claim.4In the semiconductor substrate manufacturing apparatus described in the above,Silicon carbideIt is also a processing standard for cutting out ingots. And such a processing standard as a pedestalSilicon carbideProvided integrally with the ingotAt the same time, when the silicon carbide ingot is cut out, this pedestal is cut out together.So, based on the above pedestalSilicon carbideThe ingot cutting accuracy is also maintained higher.
  Furthermore, a first reference plane serving as a reference for fixing the seed crystal on the pedestal andWire dischargeBy providing each of the second reference surfaces serving as a reference for fixing the pedestal during processing (fixing to the table), both the fixation of the seed crystal to the pedestal and the fixing of the pedestal to the table or the like are facilitated. In addition, it is possible to set the reference plane separately for fixing the seed crystal and for fixing the pedestal, and the degree of freedom in designing the pedestal is increased.
  In addition, the second reference plane of the pedestal is further formed as a plane orthogonal to the plane on which the seed crystal of the pedestal is fixed. Accordingly, in addition to the positional relationship between the pedestal and the seed crystal in the X (horizontal) and Y (longitudinal) directions, the positional relationship between the pedestal and the surface on which the seed crystal is fixed is easily defined. , Mentioned aboveWire dischargeIt becomes easier to set a processing standard for processing.
[0015]
  Incidentally, it is desirable that the first reference surface has a high flatness and a large area. ThisWire dischargeThe pedestal can be stably fixed to a processing table or the like, and as a result, the processing accuracy can be increased. However, above the pedestalWire dischargeThe reference surface for processing does not necessarily need to be a flat surface, and basically may have any shape as long as the positional relationship with the surface on which the seed crystal is fixed is clear.
On the other hand, in the semiconductor substrate manufacturing method or the semiconductor substrate manufacturing apparatus, the seed crystal having a known crystal orientation is used, and the known crystal orientation and the silicon carbide ingot formed by the wire electric discharge machining are used. The same kind crystal is fixed to the pedestal in a state where the first and second reference planes of the pedestal serving as a reference for cutting are associated with each other. In other words, since the crystal orientation of the silicon carbide ingot grown from the seed crystal is the same as that of the seed crystal, if this association is made when the seed crystal is fixed to the pedestal, the crystal of the silicon carbide ingot will be renewed. Without performing orientation measurement or the like, the silicon carbide ingot can be cut out in a desired crystal orientation according to the known crystal orientation. When the second reference surface of the pedestal is formed as a surface orthogonal to the surface to which the seed crystal is fixed, as in the manufacturing method or the manufacturing apparatus according to claim 1 or claim 4, It is particularly easy to set a processing standard when cutting out the silicon carbide ingot by the wire electric discharge machining.
When the crystal orientation becomes clear in this way, in the manufacturing method and manufacturing apparatus of the present invention for cutting out a silicon carbide ingot by wire electric discharge machining, as described above, the first and second reference planes of the pedestal corresponding to the crystal orientation are used as a reference. As with the pedestal,
(A) A silicon carbide ingot is cut into a substantially cylindrical shape.
Alternatively, (b) the silicon carbide ingot is cut into a substantially cylindrical shape including a fixed reference when slicing the wafer into a wafer.
Alternatively, (c) a silicon carbide ingot is cut into a substantially cylindrical shape including a notch surface similar to an orientation flat shape or notch shape as a final wafer.
The cutting in this manner is effective for cutting out the silicon carbide ingot in the desired crystal orientation. In any of these cases, if there is a deviation between the base of the pedestal and the reference of the crystal orientation, or if it is desired to incline by a predetermined angle with respect to the reference of the pedestal, further a predetermined angle from the crystal orientation axis For example, when the silicon carbide ingot is desired to be tilted, the above-described silicon carbide ingot is also cut out in a substantially cylindrical shape having a shape inclined by a predetermined angle corresponding to the amount of deviation or the angle to be tilted.
Further, as in the above manufacturing method or manufacturing apparatus, a wire electric discharge machining or wire electric discharge machining apparatus is effective in which electric discharge is generated between the wire and the silicon carbide ingot and the silicon carbide ingot is cut into an arbitrary shape and size. . In the wire electric discharge machining, it is desirable to sufficiently supply the machining fluid, for example, by cutting out a silicon carbide ingot in water. This makes it possible to suppress inconveniences such as wire cutting and discharge traces remaining on the ingot processed surface. Further, when the silicon carbide ingot is cut into the substantially cylindrical shape together with the pedestal through the wire electric discharge machining, the pedestal is made of a conductive material as described above for convenience of causing the discharge between the pedestal and the pedestal. Of course, it is desirable to use a conductive material as an adhesive for fixing the seed crystal to the pedestal.
According to such a semiconductor substrate manufacturing method or semiconductor substrate manufacturing apparatus, even if the ingot to be cut out is made of extremely hard silicon carbide, it causes serious damage such as chipping, cracking or cracking as described above. Thus, a desired semiconductor substrate can be obtained.
[0016]
  When the second reference surface is formed on the pedestal, the second reference surface is defined in claim 2 or claim.5It is desirable to form at least one set of mutually orthogonal surfaces as in the manufacturing method or manufacturing apparatus described in 1). Thereby, the positional relationship between the pedestal and the seed crystal in the X (horizontal) and Y (longitudinal) directions can be easily defined. Two or more sets of these orthogonal surfaces as the second reference surface may be provided. Alternatively, a surface parallel to at least one of the surfaces may be additionally formed. In particular, when a surface parallel to one of the orthogonal surfaces is additionally formed, the formation of the first reference surface with respect to the pedestal can be omitted.
[0021]
  The semiconductor ingot thus cut out is further claimed.3Or claims6A desired semiconductor substrate can be obtained by slicing into a wafer shape as in the manufacturing method or manufacturing apparatus described in 1). For the slicing here, a conventionally known inner peripheral cutting device, blade saw, wire saw or the like can be used.Wire dischargeBy adopting the processing, it is possible to obtain a high-quality semiconductor substrate free from chipping, cracking, cracks, and the like.
[0025]
  Further, when the wire electrical discharge machining apparatus is used as a semiconductor substrate manufacturing apparatus,7As in the manufacturing apparatus described in 1), the cutout shape and dimensions of the semiconductor ingot are determined according to the relative angle and relative movement amount between the wire and the table set through numerical control, for example. With such a configuration, the accuracy required for the processing is naturally increased.
[0026]
  And in this case, the claim8If the relative angle between the wire and the table is set according to the crystal orientation of the semiconductor ingot as in the manufacturing apparatus described in 1), a deviation occurs between the reference of the pedestal and the reference of the crystal orientation. In such a case, the angle correction is appropriately performed.
[0027]
  Further, when the wire electrical discharge machining apparatus is used as a semiconductor substrate manufacturing apparatus,9When the semiconductor ingot is cut out in a substantially cylindrical shape by a wire as in the manufacturing apparatus described in the above, the table is provided with ingot support means for supporting the cut out semiconductor ingot so that the cut out semiconductor ingot does not fall, The cut out semiconductor ingot is prevented from falling, and the ingot to be the semiconductor substrate can be suitably maintained.
[0028]
  Similarly, when the wire electric discharge machining apparatus is used as a semiconductor substrate manufacturing apparatus,10If the wire electric discharge machining apparatus is provided with a plurality of wires that are fed simultaneously at the time of cutting out a semiconductor ingot, in particular, the slicing process, as in the manufacturing apparatus described in 1), the production efficiency for manufacturing a semiconductor substrate can be increased. Can be greatly increased.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a semiconductor substrate manufacturing method and a manufacturing apparatus according to an embodiment of the invention will be described in detail with reference to the drawings.
[0030]
The method and apparatus for manufacturing a semiconductor substrate according to this embodiment cuts a semiconductor substrate into an arbitrary shape and size from the semiconductor ingot on the basis of a base on which the semiconductor ingot is fixed. In the present embodiment, silicon carbide is used as a material for the semiconductor ingot, and a non-contact machining apparatus, specifically, a wire electric discharge machining apparatus is used for the cutting.
[0031]
First, the structure of a pedestal used in this embodiment, the shape of a semiconductor ingot that is crystal-grown based on the pedestal, and the outline of the cut-out mode will be described with reference to FIGS.
[0032]
As shown in FIG. 1, the pedestal 10 is formed in a substantially disk shape, and the flatness of the surface thereof is enhanced. The substantially disk-shaped pedestal 10 has a diameter that is at least larger than that of the seed crystal and has a sufficient thickness to support the semiconductor ingot. In the present embodiment, a conductive material such as carbon is adopted as the material of the base 10. Incidentally, a material (silicon carbide) of the same quality as the semiconductor ingot may be used as the pedestal 10.
[0033]
Here, the pedestal 10 is provided with a first reference surface 10a serving as a processing reference for cutting out the semiconductor ingot and a second reference surface 10c serving as a reference for fixing the pedestal 10 during wire electric discharge machining. .
[0034]
The first reference surface 10a is provided on one surface (the lower surface in FIG. 1) of the pedestal 10, and the surface has a high flatness. The other surface (upper surface in FIG. 1) of the pedestal 10 is a seed crystal fixing surface 10b, and is provided in parallel to the first reference surface 10a in the present embodiment. A seed crystal is bonded and fixed to the seed crystal fixing surface 10b at a position indicated by a one-dot chain line in FIG. In the present embodiment, a conductive adhesive is also used as an adhesive, which will be described later, used for this adhesive fixing.
[0035]
The second reference surface 10c includes an X-axis reference surface 10d provided by cutting out a part of the outer peripheral side surface of the pedestal 10 linearly, and an outer peripheral side surface of the pedestal 10 that is orthogonal to the X-axis reference surface. And a Y-axis reference surface 10e provided by cutting out a part in a straight line. The X-axis reference surface 10d and the Y-axis reference surface 10e are formed orthogonally to the seed crystal fixing surface 10b, and the positional relationship between the pedestal 10 and the seed crystal in the X (horizontal) and Y (vertical) directions. Indicates.
[0036]
FIG. 2 shows the relationship between the pedestal 10 configured in this way and the semiconductor ingot 13 grown from the seed crystal 12 bonded and fixed to the pedestal 10. As shown in FIG. 2, a seed crystal 12 of silicon carbide is bonded and fixed to the pedestal 10 via an adhesive 11 applied on the seed crystal fixing surface 10b. The seed crystal 12 is bonded and fixed in parallel with the first reference surface 10a as well as the seed crystal fixing surface 10b. From this seed crystal 12, a semiconductor ingot 13 made of silicon carbide is also grown in a direction away from the seed crystal fixing surface 10b.
[0037]
Here, in the present embodiment, after the semiconductor ingot 13 is thus grown, the crystal orientation is measured using a crystal orientation measuring device (not shown). Specifically, with reference to the first reference surface 10a and the second reference surface 10c provided on the pedestal 10, the orientation (axial orientation) or orientation flat as the slice surface of the semiconductor ingot 13 fixed to the pedestal 10 is used. The crystal orientation such as the orientation and tilt of the plane is measured.
[0038]
Incidentally, the two-dot chain line in FIG. 2 indicates the cut-out shape of the semiconductor ingot 13 determined based on the measurement result. In the present embodiment, as shown in FIG. 2, the semiconductor ingot 13 crystal-grown on the pedestal 10 is formed with the pedestal 10 with the first reference surface 10a and the second reference surface 10c of the pedestal 10 as a reference. Both are cut out as a substantially cylindrical semiconductor ingot 13a in which the orientation flat 14 is formed. In the example of FIG. 2, when the semiconductor ingot 13 a is cut out in this way, as shown by the alternate long and short dash line in FIG. 2, the crystal orientation axis is based on the measurement of the crystal orientation with respect to the center line of the semiconductor ingot 13. In this case, the shape is cut into a shape inclined by a predetermined angle θ.
[0039]
Next, a wire electric discharge machining apparatus that cuts the semiconductor ingot 13 fixed to the pedestal 10 into an arbitrary shape and size will be described with reference to FIGS.
[0040]
As shown in FIGS. 3 and 4, this processing apparatus mainly includes a table 20 for fixing the base 10, a wire 30 for cutting out the semiconductor ingot 13 fixed to the base 10 in the above-described manner, and a base. 10 and a support plate (ingot support means) 40 for supporting the semiconductor ingot 13.
[0041]
Here, the pedestal 10 to which the semiconductor ingot 13 is fixed (crystal-grown) spans the through hole 20a in which the outer peripheral end portion of the first reference surface 10a is formed in the table 20, and the table 10 It is mounted so as to be fixed in contact with 20. At this time, the pedestal 10 is formed so that the second reference plane 10c (X-axis reference plane 10d, Y-axis reference plane 10e) provided on the pedestal 10 corresponds to the second reference plane 10c. By being engaged with a reference plane in the X (horizontal) and Y (vertical) directions provided on the table 20, the positional relationship with the table 20 is defined. Then, in a state where the positional relationship between the table 20 and the pedestal 10 is defined in this way, the outer peripheral end portion of the pedestal 10 by the pressing member 21 provided on the table 20 and the bolt 22 that fastens the pressing member 21 to the table 20. Is fixed to the table 20.
[0042]
The table 20 is provided with an actuator (not shown) such as a motor that can freely move the table 20 in the horizontal direction including rotation. Then, the relative movement amount of the semiconductor ingot 13 and the wire 30 fixed together with the base 10 on the table 20 is adjusted by numerically controlling the drive of the actuator.
[0043]
On the other hand, as shown in FIG. 3, the wire 30 is different from the through hole 20 a formed in the table 20 in order to cut the semiconductor ingot 13 into a substantially cylindrical shape as the table 20 moves relative to the table 20. It is arranged to intersect. Incidentally, the wire 30 is stretched between the two reels 31a and 31b in a state where tension is applied by the wire guides 32a and 32b. At the time of wire electric discharge machining described later, the reel 31b is fed out from the reel 31a. It is designed to be wound up by Also here, in correspondence with FIG. 2, the relationship between the table 20 and the wire 30 is shown for the case where the semiconductor ingot 13 is cut out in a state corresponding to the center line of the semiconductor ingot 13 and tilted by a predetermined angle θ. ing. In the present embodiment, the angle θ is set and secured through the arrangement angle of the wire guides 32a and 32b.
[0044]
On the other hand, one electrode of a pulse power source 33 is connected to the wire 30, and the other electrode of the pulse power source 33 is connected to the semiconductor ingot 13. As a result, each time a pulse voltage is applied from the pulse power supply 33, a discharge occurs between the wire 30 and the semiconductor ingot 13, and the semiconductor ingot 13 in the vicinity of the wire 30 is locally heated and melted. It becomes like this. Further, by adjusting the relative movement amount with respect to the table 20 to which the pedestal 10 is fixed with the wire 30 as a base point through the above-described numerical control, the substantially cylindrical shape including the orientation flat 14 from the semiconductor ingot 13 together with the pedestal 10. The semiconductor ingot 13a is cut out. Incidentally, although illustration is omitted for the sake of convenience, in such a wire electric discharge machining apparatus, the wire 30 is disconnected or the surface of the semiconductor ingot 13a (cutout surface) is discharged by cutting by the discharge in the machining liquid. Suppressing the leaving of marks.
[0045]
Further, the support plate 40 (ingot support means) is arranged so that the substantially cylindrical semiconductor ingot 13a cut out by the wire electric discharge machining does not fall from the through hole 20a from the base 10 ( More precisely, the first reference surface 10a) supports the semiconductor ingot 13a. And this support plate 40 is fixed to the back surface of the table 20 with the volt | bolt 41 so that it may become the same height as the table 20 to which the said 1st reference surface 10a of the base 10 is fixed. The support plate 40 is attached at a position that does not obstruct the progress of the wire 30 in the direction in which the wire 30 is inserted into the semiconductor ingot 13 in the initial stage of the electric discharge machining (FIG. 3). In accordance with the progress of processing, the wire 30 is changed to a portion where the progress of the wire 30 is completed (FIG. 4). Thereby, the stable cutting | disconnection is performed, suppressing the fall of the semiconductor ingot 13a.
[0046]
FIGS. 5-9 shows an example of the manufacturing procedure about the manufacturing method of the semiconductor substrate manufactured using such a manufacturing apparatus, hereafter, referring also to FIGS. The manufacturing method according to the embodiment will be described in detail.
[0047]
In manufacturing the semiconductor substrate, first, as shown in FIG. 5, the adhesive 11 is applied to the seed crystal fixing surface 10b provided in parallel with the first reference surface 10a provided on the pedestal 10. A seed crystal 12 is pasted. Then, a semiconductor ingot is grown on the base 10 on which the seed crystal 12 is fixed.
[0048]
FIG. 6 shows a state of the semiconductor ingot 13 thus generated (crystal growth) on the base 10. After the semiconductor ingot 13 is thus generated, the positional relationship between the base 10 and the semiconductor ingot 13 is measured using a crystal orientation measuring device (not shown). Specifically, with reference to the first reference surface 10a and the second reference surface 10c provided on the pedestal 10, the crystal orientation such as the orientation (axis orientation) as the slice plane and the orientation as the orientation flat surface is measured. To do.
[0049]
Thereafter, the XY direction of the second reference surface 10c (X-axis reference surface 10d, Y-axis reference surface 10e) and the XY direction of the table 20 shown in FIGS. Secure to the table 20. Then, when the first reference surface 10a and the second reference surface 10c are compared with the measured crystal orientation, for example, when it is necessary to incline the axis orientation by the angle θ as an off angle, FIG. The inclination of the wire 30 is determined so as to have a desired shape as shown.
[0050]
And as shown in FIG.
(A) First, the relative movement mode with respect to the table 20 is such that the wire 30 starts from the X-axis reference plane 10d of the base 10 and moves toward the central portion of the semiconductor ingot 13 corresponding to the position where the orientation flat 14 is to be formed, for example. Be controlled.
(B) Thereafter, the relative movement mode of the wire 30 and the table 20 is controlled so that the semiconductor ingot 13 is cut out along the circumferential direction.
(C) Finally, the relative movement mode of the wire 30 and the table 20 is controlled so that the wire 30 is linearly moved in accordance with the orientation of the orientation flat 14 and reaches the starting point.
In this manner, the semiconductor ingot 13 is cut out together with the base 10.
[0051]
In such cutting (electric discharge machining) using the wire 30, if the start point and the end point are the same, a minute protrusion as shown as B in FIG. 2 may be generated. Since these protrusions can cause cracks and chipping in later processes, in the present embodiment, after the wire 30 reaches the end point, a finishing process is performed to remove such protrusions. 3 corresponds to a cross-sectional view when the wire 30 and the table 20 are relatively moved to the position shown by the arrow C1 in FIG. 7, and FIG. 4 shows the arrow C2 in FIG. This corresponds to a cross-sectional view when the wire 30 and the table 20 are relatively moved to the position indicated by.
[0052]
When the finishing process is performed in this manner, an unnecessary portion on the outer periphery of the semiconductor ingot 13 is removed, and the substantially cylindrical semiconductor ingot 13a in which the orientation flat 14 is formed is taken out in the manner shown in FIG. Then, as shown in FIG. 9, the position of the wire 30 is set again according to the slice plane orientation, and the semiconductor substrate 15 is cut out by slicing the semiconductor ingot 13a to a predetermined thickness.
[0053]
As described above, according to the present embodiment, the effects listed below can be obtained.
(1) In this embodiment, the pedestal 10 provided with the first reference surface 10a and the second reference surface 10c is used for crystal growth of the semiconductor ingot 13, and wire electric discharge machining is performed using these reference surfaces as a reference. The semiconductor ingot 13 was cut out by the above. As a result, the positional relationship between the base 10 and the table 20 that is moved relative to the wire 30, and thus the positional relationship between the semiconductor ingot 13 and the table 20, is always maintained, and the processing accuracy can be maintained high. become able to. In addition, since the semiconductor ingot 13a and the semiconductor substrate 15 are cut out by causing a discharge between the wire 30 and the semiconductor ingot 13, damage to the semiconductor ingot 13a and the semiconductor substrate 15 can be suppressed. A high-quality semiconductor substrate can be manufactured stably.
[0054]
(2) In this embodiment, since the seed crystal 12 of the semiconductor ingot 13 is fixed to the pedestal 10 with reference to the first reference surface 10a provided on the pedestal 10, the semiconductor ingot 13 itself is the pedestal of the pedestal. The crystal is grown with reference to one reference plane 10a. In addition, since the semiconductor ingot 13 is cut out using the first reference surface 10a as a processing reference, the cutting accuracy is also maintained high.
[0055]
(3) In this embodiment, since the flatness of the first reference surface 10a is increased and the area is larger than that of the seed crystal 12 and the semiconductor ingot 13, the pedestal 10 is stably fixed to the table 20. As a result, the processing accuracy can be increased. Further, the plane parallel to the first reference surface 10a is used as the seed crystal fixing surface 10b to which the seed crystal 12 is bonded, so that the positional relationship between the first reference surface 10a and the seed crystal 12 is uniquely determined. be able to.
[0056]
(4) Furthermore, in this embodiment, as the second reference surface 10c, the X-axis reference that defines the X (horizontal) and Y (vertical) directions of the seed crystal 12 by cutting out the outer peripheral side portion of the base 10 is provided. The surface 10d and the Y-axis reference surface 10e were provided, and these were formed so as to be orthogonal to the seed crystal fixing surface 10b. Therefore, it becomes easier to fix the base 10 to the table 20.
[0057]
(5) In this embodiment, after crystal growth of the semiconductor ingot 13 on the pedestal 10, the crystal orientation is measured with reference to the pedestal 10. Therefore, even when a seed crystal whose crystal orientation is not clear is fixed to the pedestal, the semiconductor ingot can be cut out in a desired crystal orientation.
[0058]
(6) In this embodiment, the relative angle between the table 20 and the wire 30 is determined based on the measurement value of the above (5), and the relative movement amount between the table 20 and the wire 30 is controlled by numerical control. It was. Therefore, even when the substantially cylindrical semiconductor ingot 13a in which the orientation flat 14 is formed is cut out from the semiconductor ingot 13, it can be cut out with high degree of freedom and accurately.
[0059]
(7) Furthermore, in this embodiment, even if the cut out semiconductor ingot 13a is silicon carbide with extremely high hardness, a desired semiconductor substrate is obtained without causing serious damage such as chipping, cracking, and cracking. be able to.
[0060]
(8) In this embodiment, since the semiconductor ingot 13a is cut out from the semiconductor ingot 13 into a substantially cylindrical shape and then sliced to take out the semiconductor substrate 15, the outer diameter of the semiconductor substrate and the wafer plane High dimensional accuracy can be maintained. Moreover, since these cutting-outs can be performed only by changing the setting position of the wire 30, the processing efficiency can also be improved.
[0061]
Note that the method and apparatus for manufacturing a semiconductor substrate according to the present invention are not limited to the above-described embodiment, and can be implemented, for example, in the following manner by appropriately changing the embodiment.
[0062]
In the embodiment described above, the crystal orientation was measured after the crystal growth of the semiconductor ingot 13, but the seed crystal having a known crystal orientation was adhered to the base 10 in a state associated with the reference surface of the base 10 serving as a reference for the cutting. In some cases, the crystal orientation of the semiconductor ingot need not be measured again. That is, since the crystal orientation of the semiconductor ingot grown from the seed crystal is the same as that of the seed crystal, the crystal orientation can be set to a desired crystal orientation with reference to the reference plane of the associated pedestal 10 without performing crystal orientation measurement. It is possible to cut out the semiconductor ingot. In any of these cases,
a. When there is a discrepancy between the base standard and the crystal orientation standard. Or
b. When you want to tilt the base by a certain angle. Moreover
c. When you want to incline by a certain angle from the crystal orientation axis.
For example, the semiconductor ingot can also be cut out in a substantially cylindrical shape having a shape inclined by a predetermined angle corresponding to the deviation amount and the angle to be inclined.
[0063]
In the above embodiment, when the substantially cylindrical semiconductor ingot 13a is cut out from the semiconductor ingot 13, the orientation flat 14 indicating the crystal orientation is formed at the same time. However, the cut out shape may be changed as appropriate. That is, the shape of the fixed reference when slicing the semiconductor ingot into a wafer shape is arbitrary, and the fixed reference may be formed by a notch or other shape instead of the orientation flat 14.
[0064]
In addition, when the relationship between the crystal orientation of the semiconductor ingot and the processing standard of the pedestal is clear, the cutting of the semiconductor ingot into the substantially cylindrical shape is omitted, and the reference plane of the pedestal corresponding to the crystal orientation ( It is also possible to slice the semiconductor ingot directly into a wafer shape on the basis of the processing standard. Incidentally, in this case as well, in the cases a to c described above, the semiconductor ingot is also sliced into the wafer shape with a shape inclined by a predetermined angle corresponding to the deviation amount and the angle to be inclined. Become.
[0065]
In the above embodiment, the seed crystal fixing surface 10b is a surface parallel to the first reference surface 10a. However, as long as the relationship between the both surfaces is clarified as a dimension or an angle, it is not necessarily required to be parallel. Absent.
[0066]
The first reference surface 10a does not necessarily need to be flat, and may basically have any shape as long as the positional relationship with the seed crystal fixing surface 10b is clear. In the above embodiment, the X-axis reference surface 10d and the Y-axis reference surface 10e are orthogonally provided as the second reference surface 10c, but two or more sets of these second reference surfaces may be provided. Good.
[0067]
Alternatively, a surface parallel to at least one of the surfaces may be additionally formed. In particular, when a surface parallel to one of the X-axis reference surface 10d and the Y-axis reference surface 10e is additionally formed, the formation of the first reference surface 10a with respect to the pedestal 10 can be omitted.
[0068]
In the above embodiment, the first reference surface 10a of the pedestal 10 is brought into contact with the table 20, and the upper part of the pedestal 10 is pressed by the pressing member 21 and fixed by the bolts 22, but the pedestal 10 and the table 20 are fixed. You may change suitably the fixed aspect. For example, a cylindrical concave portion may be formed on the back surface of the pedestal, and a convex portion corresponding to the concave portion may be provided on the table 20 so as to be fitted.
[0069]
In the above embodiment, the substantially cylindrical semiconductor ingot 13a is held by the support plate 40. Instead of the support plate 40, for example, in the groove formed in accordance with the progress of the cutting process, A conductive resin or the like may be poured to hold the semiconductor ingot 13a.
[0070]
In the above embodiment, for convenience of explanation, the case where there is one wire 30 is shown. However, if a plurality of such wires are provided particularly in the slicing process illustrated in FIG. The efficiency can be greatly increased.
[0071]
In the above embodiment, wire electric discharge machining is used for slicing, but a conventionally known inner peripheral cutting device, blade saw, wire saw, or the like may be used for the slicing.
[0072]
In the above embodiment, the case where the semiconductor ingot 13 is cut into an arbitrary shape and size by wire electric discharge machining (apparatus) that generates electric discharge between the wire 30 and the semiconductor ingot 13 has been described. However, the method and apparatus for manufacturing a semiconductor substrate according to the present invention are not limited to such a wire electric discharge machining apparatus, and can be realized by other non-contact machining such as laser machining and electron beam machining. Incidentally, when these processing methods are adopted as non-contact processing, it is not always necessary to use the conductive material described above as the base 10 and the adhesive 11.
[Brief description of the drawings]
1A and 1B are a plan view and a side view showing the shape of a pedestal used in an embodiment of a semiconductor substrate manufacturing method and manufacturing apparatus according to the present invention.
FIG. 2 is a plan view and a side view showing a state where a semiconductor ingot is crystal-grown on a pedestal.
FIG. 3 is a schematic cross-sectional view showing the structure of a wire electric discharge machining apparatus on which the pedestal and the semiconductor ingot are mounted.
FIG. 4 is a schematic cross-sectional view showing a structure of a wire electric discharge machining apparatus on which the pedestal and the semiconductor ingot are mounted.
FIG. 5 is a perspective view showing a mode in which a seed crystal is bonded to a pedestal.
FIG. 6 is a perspective view showing a state where a semiconductor ingot is crystal-grown on a pedestal.
FIG. 7 is a perspective view showing a cut-out aspect of a semiconductor ingot by wire electric discharge machining.
FIG. 8 is a perspective view showing a state where unnecessary portions on the outer periphery of the semiconductor ingot are removed.
FIG. 9 is a perspective view showing a slice processing mode of a semiconductor ingot.
FIG. 10 is a schematic view showing a peripheral processing mode of a conventional semiconductor ingot.
FIG. 11 is a schematic view showing an orientation flat forming aspect of a conventional semiconductor ingot.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Base, 10a ... 1st reference surface, 10b ... Seed crystal fixed surface, 10c ... 2nd reference surface, 10d ... X-axis reference surface, 10e ... Y-axis reference surface, 11 ... Adhesive, 12 ... Seed crystal , 13 ... Semiconductor ingot, 13a ... Semiconductor ingot, 14 ... Oriented flat, 15 ... Semiconductor substrate, 20 ... Table, 20a ... Through hole, 21 ... Holding member, 22 ... Bolt, 30 ... Wire, 31a, 31b ... Reel, 32a, 32b ... wire guide, 33 ... pulse power supply, 40 ... support plate (ingot support means), 41 ... bolt.

Claims (10)

A first reference plane parallel to the solid Teimen seed crystal crystal orientation used for the crystal growth of the silicon carbide ingot is known, electrically conductive and a second reference plane perpendicular to the solid Teimen the same type crystals Fixing the seed crystal in a state where the known crystal orientation and the first reference plane and the second reference plane are associated with each other on a pedestal made of the following materials :
Growing a crystal from the fixed seed crystal to produce a silicon carbide ingot;
Fixing the pedestal to a table for wire electric discharge machining with the second reference plane as a reference together with the seed crystal and the generated silicon carbide ingot fixed to the pedestal;
The silicon carbide ingot is formed into a substantially cylindrical shape together with the pedestal by wire electric discharge machining based on the first reference surface and the second reference surface of the pedestal fixed to the table, and the ingot is formed into a wafer. Cutting into a substantially cylindrical shape including a fixed reference when slicing into a shape, and a substantially cylindrical shape including a notch surface similar to an orientation flat shape or notch shape as a final wafer ;
A method of manufacturing a semiconductor substrate comprising: The method for manufacturing a semiconductor substrate according to claim 1, wherein the second reference surface of the pedestal is formed as at least one set of surfaces orthogonal to each other. In the manufacturing method of the semiconductor substrate of Claim 1 or 2,
The method further includes the step of slicing the silicon carbide ingot cut into a substantially cylindrical shape into a wafer shape.
A method of manufacturing a semiconductor substrate. The first reference plane parallel to the plane on which the seed crystal of the silicon carbide ingot whose crystal orientation is known is fixed, and the second reference plane orthogonal to the plane on which the same crystal is fixed are fixed to the seed crystal. A pedestal made of a conductive material associated with the known crystal orientation,
A table for wire electric discharge machining for fixing a pedestal on which a silicon carbide ingot crystal-grown from the seed crystal is fixed with reference to the second reference plane of the pedestal ;
Based on the relative movement with respect to the table, the silicon carbide ingot, together with the pedestal, is formed in a substantially cylindrical shape by wire electric discharge machining based on the first reference surface and the second reference surface of the pedestal. Similar to the substantially cylindrical shape including the fixed reference when slicing the ingot into a wafer, and the orientation flat shape or notch shape as the final wafer
A wire electric discharge machining apparatus that cuts out into any one of substantially cylindrical shapes including a cut-out surface to be cut;
A semiconductor substrate manufacturing apparatus comprising: The second reference plane before Symbol pedestal, a semiconductor substrate manufacturing apparatus according to claim 4 comprising formed as at least one pair of orthogonal surfaces to each other. In the manufacturing apparatus of the semiconductor substrate of Claim 4 or 5,
The wire electric discharge machining apparatus is further sliced into wafers of silicon carbide ingot cut out in the generally cylindrical
A semiconductor substrate manufacturing apparatus . The wire electric discharge machining apparatus, any one of claims 4-6 wherein the wire and is intended to determine the cut-out Shi shape and dimensions of the silicon carbide ingot according to the relative angle and relative movement amount between the table The manufacturing apparatus of the semiconductor substrate as described in 2. The relative angle between the wire and the table is set according to the crystal orientation of the silicon carbide ingot.
The semiconductor substrate manufacturing apparatus according to claim 7 . The said table is provided with the ingot support means which supports this so that the cut out silicon carbide ingot may not fall at the time of cutting out the substantially cylindrical shape of the said silicon carbide ingot by the said wire . The manufacturing apparatus of the semiconductor substrate as described in any one . The semiconductor substrate manufacturing apparatus according to any one of claims 4 to 9, wherein the wire electric discharge machining apparatus includes a plurality of wires that are simultaneously fed when the silicon carbide ingot is cut out .

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