JP3834427B2 - Graphite jig for cutting single crystal ingot - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a graphite jig for attaching a single crystal ingot when a semiconductor or a single crystal ingot used for a dielectric is cut into slices.
[0002]
[Prior art]
The cutting process for producing a wafer from a single crystal ingot is mainly performed by an inner peripheral cutting apparatus. However, with the increase in diameter of the ingot, there are problems such as a decrease in material yield due to an increase in blade thickness and a decrease in productivity due to an increase in cutting time, and the ingot processing is shifted to a wire saw processing.
[0003]
The wire saw keeps feeding the wire at a high speed, and when the wire comes into contact with the workpiece, slurry containing abrasive grains is supplied, and the workpiece is cut into slices. Therefore, it exhibits very excellent characteristics for thinly cutting hard and brittle materials.
[0004]
Recently, a wire saw for cutting a brittle material such as a single crystal ingot that can detect the cutting state by supplying electricity to the wire during the cutting process has been developed (Japanese Patent Laid-Open No. 8-112748). For detection of the cutting state, two types of electrodes are embedded in advance in the graphite jig that supports the workpiece to detect the cutting state, and each electrode detects the current flowing in the wire during cutting. . Each electrode is configured to send a current detection signal to a control unit in the apparatus through a fixing bracket to which a graphite jig is fixed. Specifically, first, when a wire comes into contact with a processed object, the current from the wire is detected by one electrode that detects a cutting start state embedded in graphite as a conductor through the processed object. . Next, the other electrode placed on the graphite jig so that the surface is coated with an insulator layer and the coated surface is bonded to the bottom surface of the processed object, the wire cuts the processed object, and this electrode When the surface insulating layer is broken, that is, the state where the cutting is finished is detected. In this way, each electrode detects the current flowing through the wire and sends a signal to the control unit of the apparatus through the fixture to recognize the cut state.
[0005]
Therefore, if the graphite jig in which each electrode is embedded and the fixture that receives the signal from each electrode are not insulated, the device cannot recognize which electrode the signal is from. It may cause malfunction.
[0006]
For this reason, conventionally, an insulator such as a glass plate is sandwiched between the graphite jig and the fixing bracket to ensure insulation. However, in this conventional method of sandwiching an insulator such as a glass plate when cutting a single crystal ingot for semiconductor production, impurities contained in these insulators may be mixed, so cutting without using this insulator There is a need for a method that can do this. In addition, in the case of this conventional method, an extra member such as an insulating material such as a glass plate is required, and an extra step for performing the bonding is increased, which is also a problem in improving work efficiency. Yes.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and is a wire-type cutting device that can detect the cutting state, and when cutting a single crystal ingot, it reliably insulates the graphite jig and the fixing bracket attached to the device. An object of the present invention is to provide a graphite jig for cutting a single crystal ingot that can be performed.
[0008]
[Means for Solving the Problems]
That is, according to the first aspect of the present invention, one surface is formed as a concave surface capable of integrally fixing a side surface of a columnar single crystal ingot, and the other surface facing the concave surface is a mold on the cutting device side. A graphite jig formed on an attachable attachment surface and partially cut when the ingot is cut, and for cutting a single crystal ingot having an insulating polymer film formed on the entire attachment surface It is a graphite jig.
[0009]
By forming an insulating polymer film on the mounting surface of the graphite jig in advance, even if there is a mounting failure such as uneven application of the adhesive when mounting to the fixture with an adhesive, the insulating property that has been formed in advance The polymer film ensures complete insulation between the graphite jig and the device. In addition, the amount of impurities coming from the insulator can be greatly reduced.
[0010]
The invention according to claim 2 is the graphite jig for cutting a single crystal ingot according to claim 1, wherein the insulating polymer film has a thickness of 1 to 100 μm.
[0011]
In the case where the film thickness is 1 μm or less, when a scratch or the like is generated on the film surface, electricity may flow through the scratch, which is not preferable. Moreover, although it is possible to form the thickness up to about 100 μm, if the thickness is further increased, peeling of the film is likely to occur, and voids are likely to be generated in the film. It is also possible to flow into From these things, the range of 5 micrometers-50 micrometers is still more preferable.
[0012]
The invention according to claim 3 is the wire-type cutting device according to claim 1 or 2, wherein the cutting device is a wire-type cutting device capable of detecting a cutting state by passing an electric current through a wire for cutting the single crystal ingot and automatically cutting the wire. This is a graphite jig for ingot cutting.
[0013]
Since the insulating film is formed in advance on the mounting surface of the graphite jig to the fixture, it is possible for the device to reliably recognize the signal from the electrode that detects the cutting state, and to prevent malfunction of the device.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will be described below with reference to the drawings.
[0015]
FIG. 1 shows a schematic diagram of an example of a cutting graphite jig according to the present invention. In the figure, the graphite jig 1 includes a graphite base material 11 and an insulating polymer film 12.
[0016]
The material of the graphite substrate 11 to be used is not particularly limited, and there is no particular problem if it is a graphite material produced by a general manufacturing method. The graphite substrate 11 is processed into an arc-shaped concave surface 11a so that the columnar single crystal ingot can be fixed integrally. Further, the hole 13 for embedding the electrode for detecting the cut state is processed. Here, if the article to be processed can be fixed integrally, the shape to be processed into the concave surface 11a is not particularly required to be an arc shape, and may be a rectangular shape or the like.
[0017]
Next, an insulating polymer film is applied to the entire mounting surface 11b to the fixing bracket facing the processed concave surface 11a. Here, the mounting surface 11b is not limited to a flat surface as shown in the drawing, and may be a surface having fine grooves formed in order to improve the adhesiveness of the adhesive. Further, the attachment surface 11b is a portion that is processed in accordance with the attachment portion on the apparatus side and is in contact with the attachment portion on the apparatus side. Furthermore, it is preferable to apply also to the side surfaces 11c and 11d other than the mounting surface 11b because insulation can be ensured more reliably. The insulating polymer film 12 to be formed is not particularly limited as long as the heat resistant temperature is 80 ° C. or higher, and may be either a thermoplastic resin or a thermosetting resin, and may be used alone or in combination. Here, when the graphite jig is fixed to the fixture with an adhesive, it is necessary to appropriately select the material of the polymer film to be formed in consideration of compatibility with the adhesive to be used. This is not the case when mechanically fixed.
[0018]
Resins that can be used for the insulating polymer film 12 include thermoplastic resins such as polyolefins such as polystyrene, polyethylene, and polypropylene, polyesters such as polyethylene terephthalate, polycarbonates, polyamides, polyimides, and the like. An epoxy resin, a phenol resin, a melamine resin, etc. are mentioned. These resins are applied alone or in combination of two or more. In the case where an adhesive is used for fixing the graphite jig to the fixing metal, particularly compatible polymers are epoxy resin, polyimide resin, and the like. The application method is appropriately selected such as brush coating or spray coating. Here, the epoxy resin is applied to the entire contact surface so as to have a uniform thickness of about 20 μm, and the resin is cured in a dryer having a maximum temperature of 350 ° C.
[0019]
The graphite jig 1 having the insulating polymer film 12 formed as described above is provided with an electrode 26 whose surface for detecting the completion of cutting is coated with an insulator on the graphite jig 1 14, and a single crystal ingot 22 is fixed with an adhesive. The adhesive is applied to the entire bottom surface of the concave surface 11a of the graphite jig 1, and a single crystal ingot is placed thereon.
[0020]
FIG. 2 is a schematic view showing a state where the single crystal ingot 22 is fixed to the graphite jig 1 with an adhesive. In the figure, 21 is a fixture for fixing to the apparatus, 22 is a single crystal ingot, 23 is a wire saw, 24 is an electrode for detecting a cutting start state, 25 is a cable for transmitting a signal from the electrode 24 to the fixture 21, Reference numeral 26 denotes an electrode for detecting the completion of cutting, and 27 denotes a cable for transmitting a signal of the electrode 26 to the fixture 21.
[0021]
After the single crystal ingot 22 is fixed, the graphite jig 1 is fixed to a fixing bracket 21 attached to the apparatus. This fixing includes a method of using an adhesive and a method of mechanically fastening with a vise or the like. In either case, insulation can be ensured by previously forming the insulating polymer film 12 on the attachment surface 11b of the graphite jig 1 to the fixture 21.
[0022]
The cutting is performed by a wire saw 23 that is driven at a high speed in a vertical and horizontal direction as indicated by an arrow in the figure on a table to which the fixing metal 21 is fixed. A current for detecting the cutting state flows through the wire saw 23. When the wire-saw 23 comes into contact with the ingot 22, it is detected that the current flowing through the wire saw 23 is started to be cut by the electrode 24 through the ingot 22 and through the graphite jig 1 as a conductor. Next, when the wire saw 23 cuts the ingot 22 and breaks the insulator covered with the electrode 26, the electrode 26 detects the current from the wire saw 23, recognizes that the cutting is complete, and Let go. Thereafter, the table moves and a new cutting is started. By repeating the above series of operations, the ingot 22 is cut into slices.
[0023]
In addition, since the present invention aims to insulate between the graphite jig 1 and the fixture 21, that is, the cutting device, the contact of the fixture 21 with the graphite jig 11 in order to maintain insulation more reliably. The resin may also be applied to the surface to form an insulating polymer film. In this way, by forming films on both the graphite jig 1 and the fixture 21, further insulation can be obtained.
[0024]
In the above-described embodiment, an example of application to a cutting device using a wire saw in which a current is passed for detecting a cutting state has been described. It can also be applied to other generated cutting devices.
[0025]
【The invention's effect】
The present invention is configured as described above, and according to the invention of claim 1 of the present invention, insulation can be ensured between the graphite jig and the apparatus, the misdetection of the cutting state can be prevented, and the malfunction of the apparatus can be prevented. . Further, contamination of impurities can be prevented.
[0026]
According to the invention of claim 2, the insulation between the graphite jig and the apparatus, which is the effect of the invention of claim 1, is further ensured.
[0027]
According to the invention of claim 3, it becomes easy to cut a large-diameter single crystal ingot, it is possible to surely perform an automatic cutting process, and an effect of reducing a semiconductor manufacturing cost can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of a graphite jig for cutting a single crystal ingot according to the present invention.
FIG. 2 is a schematic view showing a state in which a single crystal ingot is fixed to a graphite jig according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Graphite jig | tool 11 Graphite base material 12 Insulating polymer film 21 Fixing bracket 22 Single crystal ingot 23 Wire saw 24 Cutting state detection electrode

Claims (3)

One surface is formed as a concave surface capable of integrally fixing the side surface of the columnar single crystal ingot, and the other surface facing the concave surface is formed as a mounting surface that can be attached to a die on the cutting device side. A graphite jig for cutting a single crystal ingot, which is a graphite jig partially cut at the time of cutting, wherein an insulating polymer film is formed on the entire mounting surface. The graphite jig for cutting a single crystal ingot according to claim 1, wherein the insulating polymer film has a thickness of 1 to 100 μm. 3. The graphite jig for cutting a single crystal ingot according to claim 1, wherein the cutting device is a wire type cutting device capable of detecting a cutting state by passing an electric current through a wire for cutting the single crystal ingot and automatically cutting the wire.

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