JP3658920B2 - Semiconductor ingot slicing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a slicing apparatus for a single crystal ingot or other semiconductor ingot, and more particularly to a slicing apparatus for a semiconductor ingot that presses a single crystal ingot against a wire while supplying slurry to a cutting surface between the traveling wire and the semiconductor ingot. .
[0002]
[Prior art]
For example, as a slicing apparatus for a single crystal ingot, as shown in FIGS. 10 (a) and 10 (b), the workpiece b of the single crystal ingot is pivoted with respect to the inner peripheral edge a in which diamond is electrodeposited on the inner peripheral end face. This is achieved by supplying a slurry (cutting fluid) containing abrasives of cutting materials and abrasives to the wire d as shown in FIG. There is a wire saw e of a semiconductor ingot that presses a workpiece b of a single crystal ingot against a wire d and cuts a wafer by lapping action of abrasive grains.
[0003]
The former inner-blade slicer c can be sliced with higher precision than the latter semiconductor ingot slicing device e. However, because of the structure, the wafers must be cut one by one, so that the mass productivity is low. Moreover, since the tooth thickness of the inner peripheral edge a cannot be made thinner than the wire diameter of the wire d of the latter wire saw e, there is a problem that there is a lot of material loss during slicing.
On the other hand, the wire saw e has an advantage that a large number of wafers can be sliced and cut at a time because the workpiece b is pressed against a large number of wires d and sliced. Although there is an advantage that there is little loss, the slicing surface sometimes swells, and the required time including the slicing and lapping process becomes longer than when the inner peripheral slicer c is used. There's a problem.
For this reason, the inner peripheral slicer c is mainly used for ingot slices of up to 8 inches (200 mm) class.
[0004]
[Problems to be solved by the invention]
However, considering the remarkable progress of single crystal ingot pulling technology, the ingot pulling size will change from 8 inches to 12 inches, 16 inches and even 20 inches or more in the short term. There is a concern that the mere scale-up of the inner peripheral edge slicer c cannot cope with both processing time and processing cost.
For this reason, it is desired to improve the problem of waviness, which is a weak point of a semiconductor ingot slicing apparatus, and to maximize the mass productivity that is an advantage.
[0005]
Then, the work of the single crystal ingot of diameter 200mm and diameter 300mm was sliced with the wire saw, and the state of waviness and the generation mechanism were examined.
In the wire saw, as shown in FIG. 12, a head roller f and a tail roller g in which grooves (not shown) for fitting the wires d are formed at a predetermined helical pitch on the outer peripheral surface of the roller are arranged at an appropriate interval from each other. A driving roller h having a fitting groove for the wire d is disposed substantially below the center between the rollers f and g, and the wire d is inserted into the fitting groove from the outside of the rollers f, g, and h. A special piano wire of about 08 to 0.25 mm was spirally wound. Further, as the nozzle i for supplying the slurry to the wire d, a pair of nozzles j each having a length capable of supplying the slurry to each winding part of the wire d is used, and the nozzle i is used as a head. The roller f and the tail roller g were arranged so as to cross over.
[0006]
The drive roller h is attached with a drive device (not shown) for reciprocating the wire d by switching between normal and reverse, and is driven while supplying slurry to the wire d. The workpiece b was pressed against d to cut out the wafer.
As a result, a swell that would cause a practical problem was not observed in a semiconductor ingot with a diameter of 200 mm, but a swell was large in an ingot (work) with a diameter of 300 mm, and a trace that the wire and silicon were directly rubbed was seen. It was.
[0007]
FIG. 13 (a) shows the slice state of the workpiece, and FIG. 13 (b) shows the swell generated in the semiconductor ingot having a diameter of 300 mm.
In FIG. 13A, x represents the cutting depth from the workpiece b cutting start point S to the slice completion point E. In FIG. 13B, S-E is a reference for measuring the direction and size of the swell. This corresponds to the slice section SE in FIG. In FIG. 13B, y represents the size (μm) of waviness, (+) represents the waviness on the convex side, and (−) represents the waviness on the concave side.
In addition, a contact type roughness measuring device (Perthen Pertometer or Kosaka roughness meter) was used for measurement of waviness, that is, unevenness.
[0008]
As shown in FIG. 13B, the undulation y tends to be small at the first cutting start point S, increases in proportion to the cutting length, and becomes maximum at the maximum cutting point passing through the center of the workpiece b.
Theoretically, if the friction is proportional to the drag but not proportional to the cutting area, the occurrence of swell and the extent of the slurry are out of the slurry, that is, the supply of slurry to the notch is poor (bad swallowing) It is thought that.
Therefore, even if the diameter of the semiconductor ingot is 300 mm or more, if the slurry can be continuously supplied to the entire cut and the slurry can be supplied to the cutting surface of the wire and the semiconductor ingot, the undulation caused by the slurry cut can be suppressed to a small extent. It is done.
In addition to the results shown in FIG. 13B, the swell form includes a form generated in both the concave side and the convex side as shown in FIG. 13C, and a concave shape as shown in FIG. 13D. Forms that occur only on the side are also conceivable.
[0009]
An object of the present invention is to supply a sufficient amount of slurry for cutting to the cutting surfaces of a semiconductor ingot and a wire to suppress the occurrence of waviness due to slurry cutting.
[0010]
[Means for Solving the Problems]
The present invention is achieved by the following configurations.
The invention of claim 1, wherein the plurality of rollers between a semiconductor ingot is pressed against the tensioned wire column, slurry feed products by traveling Lawah ear wafer slices containing cutting material on said wire array In a semiconductor ingot slicing apparatus for cutting,
First slurry supply means arranged so that slurry is supplied in the vicinity of the wire incident position of the ingot;
Second slurry supply means for supplying slurry to the wire surface located upstream of the first slurry supply means in the wire traveling direction and up to the first roller tensioning position, and the first slurry supply means and the second slurry supply means Each slurry supply direction of the slurry supply means is positioned toward the wire from both sides of the wire so that the slurry is evenly supplied from both the upper and lower sides of the wire, and the effect of the invention is achieved more smoothly. The slurry supply direction of the first slurry supply means is the side facing the ingot cutting surface of the wire, and the slurry supply direction of the second slurry supply means is positioned on the side pressing the wire of the ingot, whereby the slurry by the cutting surface is Along with cooling, the slurry is sufficiently supplied to the cutting surface.
In many cases, the wire is generally reciprocated to slice a wafer.
[0012]
In this case, the first slurry supply means is disposed in the vicinity of both sides of the ingot in the wire reciprocation direction, and the second slurry supply means is disposed in the direction away from the ingot from the first slurry supply means along the wire reciprocation direction . The slurry supply direction of the first slurry supply means is the side facing the ingot cutting surface of the wire, and the slurry supply direction of the second slurry supply means is located on the side pressing the wire of the ingot. The first and second slurry supply means are disposed on both sides of the ingot, respectively,
The first slurry supply means is arranged so that the slurry is supplied in the vicinity of the wire incident position, and the second slurry supply means is the first roller supply than the first slurry supply means arranged on both sides of the ingot. The slurry is arranged to be supplied to the wire surface located up to the tension position.
[0013]
That is, when the present invention is specifically described, the present invention is to complete the cut start of semiconductor ingot, to allow the supply of the slurry for cutting surface of the semiconductor ingot and the wire, further, the wire for the semiconductor ingot By supplying the slurry to the ingot incident position and causing the slurry to be entangled with the wire, the lack of slurry on the cutting surface of the wire and the semiconductor ingot is eliminated, and the occurrence of undulation due to the slurry breakage is prevented. Therefore, a large number of wafers with high cutting quality can be cut out, and cost reduction can be achieved.
According to a fourth aspect of the present invention, in the first aspect of the invention, the first and second slurry supply means are formed of a tubular body having a plurality of nozzle holes for supplying slurry to the wires, and the diameters of the nozzle holes are respectively set. It is characterized in that the diameters of the wires are set so as to increase sequentially as the distance from the slurry supply unit increases so that the slurry supply amounts to the wires are equal to each other.
[0014]
That is, according to the present invention, the nozzles for supplying slurry to each wire are provided in one tube body, and the supply amount differs for each nozzle hole due to the pipe resistance. The pipe resistance is taken into consideration for the setting of the bore diameter. Accordingly, the amount of slurry supplied to the upstream portion in the traveling direction of the wire and the cutting surface of the wire and the semiconductor ingot can be maintained at a constant value, and undulation due to insufficient slurry supply can be prevented.
[0015]
According to a fifth aspect of the present invention, in the above invention, the tube body having a plurality of the nozzle holes is covered with an outer tube in a double tube manner, and the direction in which the nozzle hole is connected to the facing portion of the outer tube with the nozzle hole. And a slit extending outward from both sides of the tube axis from the nozzle hole, and the width of the slit is set narrower than that of the nozzle hole having the minimum diameter.
The present invention allows the inside of the outer tube to function as a kind of buffer, enables uniform slurry supply in the length direction, and improves the reliability of slurry supply.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only unless otherwise specified. It is just an illustrative example.
[0017]
1 to 6 show an embodiment of the present invention, FIG. 1 is a configuration diagram showing a basic configuration of a wire saw according to this embodiment, FIG. 2 is a perspective view showing a configuration of a wire saw according to this embodiment, and FIG. Is a detailed cross-sectional view of the main part showing the structure of the slurry supply nozzle, FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3, and FIG. 5 is the diameter, pressure and flow rate of the slurry distribution port formed inside the slurry supply nozzle. FIG. 6 is a partially broken side sectional view showing the structure of a roller constituting the wire saw according to this embodiment, and FIG. 7 is a diagram showing a slurry supply system and a slurry return system for the slurry supply nozzle. .
It is.
[0018]
First, a basic configuration of a semiconductor single crystal ingot slicing apparatus according to the present embodiment will be described with reference to FIG.
As shown in FIG. 2, a head roller 2 and a tail roller 3 are disposed at an upper portion of a wire saw 1 that is a slicing device and spaced apart from each other. A roller 4 is disposed, and a single wire 5 is wound around the rollers 2, 3 and 4 at a predetermined helical pitch (wafer thickness + cutting allowance). This wire 5 cuts a wafer from the semiconductor ingot (workpiece) b in cooperation with a slurry (cutting fluid) containing a cutting material, so that it is a hard, high-tensile wire (for example, a special wire having a line diameter of 0.08 to 0.25 mm). And is fitted with a constant tension into a fitting groove (not shown) having a predetermined helical pitch (wafer thickness + cutting margin) formed on the outer periphery of the head roller 2, the tail roller 3, and the driving roller 4. And it comes to be driven without slipping. A roller driving device 6 for driving the wire 5 is attached to the driving roller 4 so as to reciprocate the wire 5 under the control of a control device (not shown) for reciprocating the wire 5 back and forth. It has become.
In the present embodiment, the head roller 2, the tail roller 3 and the driving roller 4 are formed by press-fitting a cylindrical material 9 such as a resin into a core metal 8 such as cast iron as shown in FIG. 9 is supported by the main body frame 10 of the wire saw 1.
[0019]
Now, the delivery of the semiconductor ingot b and the supply of the slurry will be described in detail as shown in FIG. 2. The work for lowering the semiconductor ingot b and pressing it against the wire 5 substantially above the center of the head roller 2 and tail roller 3. As shown in FIG. 1, the feeding device 12 is disposed between the head roller 2 and the tail roller 3, and on both outer sides B sandwiching the moving area A (lowering area) of the ingot (work) b, and Near the moving area A, a first slurry supply nozzle (first slurry supply means) 14 is provided to supply the slurry toward the cutting surface 13 between the workpiece b and the wire 5, and above the head roller 2 and the tail roller 3. In addition, a second slurry supply nozzle (second slurry supply means) 15 is provided to supply the slurry to each wire 5.
As shown in FIGS. 3 and 4, the first and second slurry supply nozzles 14, 15 have a double tube structure in which the slurry transfer pipe 16 is accommodated in the outer pipe 17. A plurality of (multiple) nozzle holes 18 are formed at the same interval P as the spiral pitch of the wire 5.
[0020]
These nozzle holes 18 are connected to the first and second slurry supply pipes 19 and 20 shown in FIG. 7 at the center of the slurry supply source (that is, the first and second slurry supply nozzles 14 and 15 in the axial direction). The diameters d1, d2, d3,..., Dn-1, dn are set so as to increase in order (d1 <d2 <d3 <...). <Dn-1 <dn), and the amount of slurry supplied from each nozzle hole 18 is kept uniform in the axial direction of the head roller 2 and the tail roller 3. A slit 21 narrower than the nozzle hole 18 having the minimum diameter d1 (B <d1) is formed in a portion facing the nozzle hole 18 of the outer tube 17 along a line connecting these nozzle holes 18 and nozzles at both ends. The outer pipe 17 is formed so as to extend to the outside appropriately from the hole 18 and functions as a kind of buffer, and the wire 5 reciprocates with respect to the cutting surface (work incident portion) 13 between the wire 5 and the workpiece b and the workpiece b. The slurry can be continuously supplied from the upper and lower sides to the wire surface up to the stretched position of the rollers 2 and 3 on the upstream side in the direction.
[0021]
The slurry supply system and the return system will be described with reference to FIG. 7. The slurry supply system includes the slurry supply tank 26 and the slurry transport pipes 16 of the first and second slurry supply nozzles 14 and 15 individually. The first and second slurry supply pipes 19 and 20 communicated with each other, and the first and second slurry supply pumps 22 and 23 interposed therebetween, respectively. The slurry return system includes a wire 5, a workpiece b, and the like. A slurry reservoir 25 for receiving the slurry dropped from the slurry, and a slurry discharge pipe 24 communicating the slurry reservoir 25 with the slurry supply tank 21.
When individual slurry supply systems are connected to the first and second slurry supply nozzles 14 and 15 in this way, the slurry supply amount can be adjusted by two independent systems, and the future large-diameter single crystal ingot can be adjusted. It can also be prepared for slices.
[0022]
The operation of this embodiment will be described below.
In order to cut out the wafer from the workpiece b with the wire saw, the first and second slurry supply pumps 22 and 23 are operated (see FIG. 7), the roller driving device 6 is operated, and the workpiece feeding device is operated. Thereby, a slurry is supplied to the wire 5 and the workpiece | work b is pressed.
When the first and second slurry supply pumps 22 and 23 are operated, the first and second slurry supply pipes 19 and 20 are connected to the connection portions of the first and second slurry supply nozzles 14 and 15 to the slurry transport pipe 16 respectively. A slurry is supplied. Slurry flows from the connecting portion toward both ends of the slurry conveying pipe 16 and flows out from each nozzle hole 18 through the ejection slit 21. As described above, the width of the slit 21 is the minimum diameter of the nozzle hole 18. Is smaller than (B <d1), the slurry in the outer tube 17 does not flow out all at once, but temporarily stays in the outer tube 17 by a kind of buffer effect. At this time, since the diameters of the plurality of nozzle holes 18 are set as d1 <d2 <d3 <... <dn-1 <dn, the slurry supply direction is caused by the pipe resistance as shown in FIG. Even if the pressure drops, the slurry supply amounts of the nozzle holes 18 are the same (see FIG. 5).
[0023]
Therefore, if such slurry supply nozzles 14 and 15 are used, a highly reliable slurry can be supplied.
When the slurry is discharged from the first and second slurry supply nozzles 14 and 15, respectively, by driving the first and second slurry supply pumps 22 and 23, as shown in FIG. When the cutting progresses, the workpiece and the wafer slicing surface are included), and a predetermined amount of slurry is supplied from below to the cutting surface, and the slurry from above in advance in the traveling direction of the wire 5 from the workpiece b. Is supplied.
As described above, in this embodiment, the slurry supplied to the wire 5 before the contact between the workpiece b and the cutting surface 13 of the wire 5 is brought into contact with the workpiece b on the slurry of the wire 5 (cutout). The wafers can be cut out without running out of the slurry by supplying the slurry continuously from the beginning to the end of the cutting.
[0024]
Therefore, the wire saw 1 according to the present embodiment can cut out a wafer having no slurries and extremely small undulations only by optimally adjusting the rotation speeds of the first and second slurry supply pumps 22 and 23. Therefore, it can contribute to the cost reduction of the wafer.
(Example)
When the semiconductor ingot is cut using the single crystal semiconductor ingot slicing apparatus (wire saw) having the above-described configuration, the rotation speeds or flow rate control valves of the first and second slurry supply pumps 22 and 23 (between each pump and each nozzle) Adjusting the opening degree of the first and second slurry supply nozzles 14 and 15 to adjust the respective slurry flow rates (slurry supply amounts) at the start of ingot cutting, at the center cutting of the ingot, and at the end of ingot cutting. The single crystal semiconductor ingot b having a diameter of 300 mm was cut by changing the slurry flow rate gradually (secondary function) from the start of cutting to the end of cutting.
Thus, the reason why the slurry flow rate is gradually changed from the start of cutting the ingot to the end of cutting is because the amount of slurry required depends on the cutting position due to the difference in the cutting length (the length where the ingot and the wire are in contact). Because it is different. Then, the most slurry is required at the center of the ingot with the longest cut length. Thus, the waviness of the wafer can be further reduced by changing the slurry flow rate according to the cutting length.
In this case, the rate of change of the respective slurry flow rates of the first and second slurry supply nozzles 14 and 15 is gradually changed (quadratic function) as shown in FIG. , 15 The slurry flow rates were varied as shown in FIG.
That is, the slurry flow rates of the first slurry supply nozzle 14 and the second slurry supply nozzle 15 are within a range of 10 to 25 l / min (20 to 50 l / min) at the start of cutting, and 25 to 25 at the time of cutting the ingot center. Within the range of 40 l / min (50-80 l / min), at the end of cutting, adjust within the range of 10-25 l / min (20-50 l / min), and at the time of cutting the ingot center from the start of cutting The slurry flow rate was adjusted so that the slurry flow rate was gradually increased until the end of cutting the ingot until the end of cutting.
As a whole, it is within the range of 20 to 50 l / min (total 40 to 100 l / min) at the start of cutting, and within the range of 50 to 80 l / min (total 100 to 160 l / min) when cutting the center of the ingot. In addition, at the end of cutting, it is adjusted within the range of 20 to 50 l / min (40 to 100 l / min), and the slurry flow rate is gradually increased from the start of cutting to the cutting of the ingot center. From the time of partial cutting to the end of cutting, the slurry flow rate was adjusted to gradually decrease. The numbers in parentheses are the total flow rate for each nozzle.
After the cutting, each wafer b was inspected for surface roughness, waviness, and scratches. As a result, the surface roughness and waviness, which are problems in practical use, were reduced, scratches were not observed, and as a result, the slurry was not cut. It was confirmed that
[0025]
【The invention's effect】
As is apparent from the above description, according to the present invention, the slurry can be continuously supplied with respect to the cutting of the semiconductor ingot, and the excellent effect of cutting out a wafer with extremely small swell due to slurry cutting can be obtained. Demonstrate.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration of a wire saw according to the present embodiment, in which FIG. 1 (a) is a front view of a semiconductor ingot slicing device viewed from the end face side of the semiconductor ingot, and FIG. It is a bb arrow directional view of (a).
FIG. 2 is a perspective view showing a configuration of a semiconductor ingot slicing device according to the present embodiment.
FIG. 3 is a detailed cross-sectional view of a main part showing a structure of a slurry supply nozzle.
4 is a cross-sectional view taken along the line IV-IV in FIG. 3;
FIG. 5 is a diagram showing a relationship between a diameter of a slurry distribution port formed inside a slurry supply nozzle, a pressure, and a flow rate.
FIG. 6 is a partially broken side sectional view showing the structure of a roller constituting the semiconductor ingot slicing device according to the present embodiment.
FIG. 7 is a diagram showing a slurry supply system and a slurry return system for a slurry supply nozzle.
FIG. 8 is a diagram showing how individual flow rate change rates of the first and second slurry supply nozzles are adjusted during ingot cutting.
FIG. 9 is a diagram showing how individual flow rates of the first and second slurry supply nozzles are adjusted during ingot cutting.
FIG. 10 is a view for explaining the structure of an inner peripheral blade slicer.
FIG. 11 is a perspective view showing a structure of a semiconductor ingot slicing device used in a cutting test of the semiconductor ingot slicing device.
12 shows an inner peripheral blade slicer as a slicing device, FIG. 12 (a) is a perspective view schematically showing the structure of the inner peripheral blade slicer, and FIG. 12 (b) is a cross section showing the structure of the inner peripheral blade slicer. FIG.
FIGS. 13A and 13B are diagrams for explaining a state of a cutting test and a state of waviness, FIG. 13A is a cross-sectional view showing the state of cutting, and FIGS. 13B to 13C are views of cutting length and waviness. It is a figure which shows the relationship with a magnitude | size.
[Explanation of symbols]
2 Head roller 3 Tail roller 5 Wire 13 Cutting surface 14 First slurry supply nozzle 15 Second slurry supply nozzle 16 Slurry transport pipe 17 Outer pipe 18 Nozzle hole b Semiconductor ingot

Claims (5)

Pressing the semiconductor ingot tensioned wire strings between a plurality of rollers, the semiconductor ingot slice apparatus slurry supplies performs slicing of the wafer by traveling Lawah ear comprising a cutting member to said wire array In
First slurry supply means arranged so that slurry is supplied in the vicinity of the wire incident position of the ingot;
Second slurry supply means for supplying slurry to a wire surface located upstream of the first slurry supply means in the wire traveling direction and up to the first roller tensioning position, and the first slurry supply means and the first slurry supply means Each slurry supply direction of the two slurry supply means is positioned toward the wire from both sides of the wire, and the slurry supply direction of the first slurry supply means is the side facing the ingot cutting surface of the wire, and the second slurry A semiconductor ingot slicing apparatus, characterized in that the slurry supply direction of the supply means is located on the side pressing the wire of the ingot. In a semiconductor ingot slicing apparatus that presses a semiconductor ingot against a wire row stretched between a plurality of rollers, and reciprocates the wire while supplying slurry containing a cutting material to the wire row to cut the wafer into slices,
First slurry supply means is disposed in the vicinity of both sides of the ingot in the wire reciprocation direction, and second slurry supply means is disposed in the direction away from the ingot from the first slurry supply means along the wire reciprocation direction. A semiconductor ingot slicing apparatus, wherein the slurry supply direction of the second slurry supply means is located on the side pressing the wire of the ingot, and the slurry supply direction of the second slurry supply means is positioned on the side pressing the wire of the ingot. In a semiconductor ingot slicing apparatus that presses a semiconductor ingot against a wire row stretched between a plurality of rollers, and reciprocates the wire while supplying slurry containing a cutting material to the wire row to cut a wafer into slices,
While disposing first and second slurry supply means on both sides of the ingot, respectively ,
The first slurry supply means, respectively the slurry is arranged to be supplied to the vicinity of the wire incident position,
The second slurry supply means is configured to supply the slurry to the wire surface located from the first slurry supply means disposed on both sides of the ingot to the first roller tensioning position . A semiconductor ingot slicing apparatus, wherein the slurry supply direction is the side facing the ingot cutting surface of the wire, and the slurry supply direction of the second slurry supply means is positioned on the side pressing the wire of the ingot. In slicer according to any one of claims 1 to 3,
The first and second slurry supply means are constituted by a tube having a plurality of nozzle holes for supplying slurry to the wires, and the diameters of the nozzle holes are set so that the slurry supply amounts to the wires are equal to each other. A semiconductor ingot slicing apparatus, characterized in that the diameter of the semiconductor ingot is sequentially increased as the distance from the supply unit increases . The slicing device according to claim 4 , wherein
The tube body having a plurality of nozzle holes is covered with an outer tube in a double tube manner, extends in a direction connecting the nozzle holes to the facing portion of the outer tube with the nozzle holes, and on both outer sides of the tube axis from the nozzle holes. A semiconductor ingot slicing apparatus, wherein an elongated slit is formed, and the width of the slit is set narrower than the nozzle hole having the minimum diameter.

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