JP3325676B2 - Slicing method of silicon ingot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for slicing a silicon ingot.

[0002]

2. Description of the Related Art Silicon is a material excellent in terms of both industrial production and resources as a material for a solar cell, and silicon solar cells which are currently in practical use for photovoltaic power generation are mostly used. However, in order to use it as a future energy source, it is necessary to further reduce costs. At present, the mainstream of solar power cells uses crystalline silicon, but in order to achieve even lower costs, it is indispensable to reduce the cost of crystalline silicon wafers. is necessary. The conventional general method of manufacturing crystalline silicon wafers for solar cells is to shape and shape a silicon ingot obtained by melting and solidifying solid silicon in a heating furnace with a band saw or peripheral blade, and then slicing with a multi-wire saw. How to do it. The breakdown of the wafer cost is 40% for ingot growth, 10% for shaping, and 50% for slicing. Therefore, in order to reduce the wafer cost, it is essential to reduce the cost of the slice processing.

The principle of cutting a multi-wire saw, which is a general method of slicing a wafer for a solar cell, and the processing steps thereof will be described below with reference to the schematic explanatory view of FIG. The multi-wire saw is, as shown in FIG.
(Usually a brass-plated piano wire) is wound around a plurality of grooved rollers 2, the rollers 2 are rotated to run the wire 1, and at the same time, the slurry 4 a in which abrasive grains are mixed with oil is applied to the wire 1.
Is a method of cutting the silicon ingot 6 while spraying the silicon ingot 6 from the nozzle 4. In the figure, reference numeral 7 denotes a processing table (fixing table for processing). The general slicing process is as follows. (1) The silicon ingot 6 is bonded to a discarded plate (carbon plate, glass plate, or the like) with an adhesive so that the wafer does not fall down after the cutting. (2) It is set on the processing table 7 and cut by the multi-wire saw 1. (3) After cutting, the wafer is peeled off from the discarded plate and stored in a cassette. (4) Wash the wafer.

[0004]

In the above-mentioned process, the wafer is stored in the cassette in the process (3) by a worker at present, and it is necessary to process a large number of wafers like a solar cell. At present, it is a major obstacle to reducing the cost of the wafer. Further, as shown in FIG. 2, in the conventional slicing method, the multi-wire saw 1 is pushed up by pushing the processing table 7 upward.
Is cut from above the silicon ingot 6 by using the wire 1 and the ingot 6.
A wedge-shaped void is likely to be generated between them, so that abrasive grains remain and adhere to this void, which causes cracks and scratches on the processed surface.

For example, Japanese Patent Application Laid-Open No. Hei.
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses a method in which the processing table 7 is arranged on the upper side, the processing table 7 is pressed down, and the silicon ingot 6 is cut from below by the multi-wire saw 1 by turning the processing table 7 downward. And
According to this means, even if voids are generated, the abrasive grains sufficiently flow by the slurry 4a, so that the above-described problem does not occur.
It has been. However, no reference is made to the process of storing the wafer in the cassette after processing the wafer, and therefore, an improvement in this regard has not yet been solved. Accordingly, an object of the present invention is to provide a silicon ingot slicing method capable of automating manual storage of silicon wafers in a cassette while maintaining high processing accuracy. is there.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and its gist is to provide a silicon ingot which is adhered to a discarded plate and further fixed on a fixing stand for processing. When the silicon ingot is sliced, the wafer storage cassette is raised to the wafer storage position after the silicon ingot is cut, and the adhesive is peeled off by heating by the heating means provided in the fixing table or the cutting means. Then, there is a method of slicing a silicon ingot in which the cut wafer is separated from the discarded plate and directly stored in the storage cassette, and in this case, the heating temperature may be in the range of 40 to 80 ° C. It is valid. That is, the first gist is a discard board
Adhered to silicon and fixed on a processing base
When slicing an ingot,
After cutting the ingot, remove the grooved wafer storage cassette.
Raise to the wafer storage position,
By heating the step, the bonded portion is peeled off, and the cut
Separating Eha from the discard plate, and separating from the discard plate
Directly storing the wafers in the storage cassette
Silicon ingot slicing method characterized by
is there. The second point is that a plurality of grooves cut at a predetermined pitch
One wire around the roller at the predetermined pitch through the groove.
And the wire moving between the rollers
Silicon ingot for slicing ingots at the predetermined pitch
In the method of slicing ngot,
And the silicon wafer fixed on a processing base.
When slicing an ingot, the silicon ingot
After cutting, the grooves are cut at the same pitch as the grooves of the rollers.
Raised wafer storage cassette to the wafer storage position.
By heating the fixed base or the wire,
Peeling off the bonded part, and removing the cut wafer from the discard plate
Storing the separated wafer and the separated wafer from the discard plate
Characterized by being stored directly in the cassette
Ingot slice method. The third point is,
The cutting means is a wire, and energizes the wire
In this way, heating can be performed by
It is in the method of slicing a coning ingot . Fourth summary
Removes the cut wafer bonded to the discard plate,
When storing in EHA storage cassette, fix for processing
Gist characterized by vibrating the table or the wire
Slicing of silicon ingot according to 2 or 3
In the way.

[0007]

According to the present invention, the heating means is provided in a processing fixture for fixing the silicon ingot or in a cutting means such as a multi-wire saw for cutting the silicon ingot, while the silicon ingot is provided below the silicon ingot. Since the wafer storage cassette is arranged so as to be able to stand up, the cutting of the silicon ingot is completed, and then the heating means is urged so that the gap between the wafer storage cassette and the discard plate adhered to the silicon ingot is removed. The adhesive softens or melts and peels off, and the sliced silicon wafer is automatically stored in the standby wafer storage cassette at the lower storage position, eliminating any manual work. No longer needed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing one embodiment of an apparatus for carrying out the silicon ingot slicing method of the present invention. As can be seen from the figure, the configuration of the device is such that three main roller portions 2 for running the wire 1 and the silicon ingot 6 are fixed to the discard plate 8 with an adhesive 9 and the discard plate 8 is fixed. Fixing base 7
Consists of Further, a cassette 5 having an elevating function for accommodating a silicon wafer after cutting the silicon ingot 6 is provided. Reference numeral 4 denotes a slurry nozzle, and reference numeral 10 denotes a heating means (heater) built in the processing base 7. Reference numerals 3a and 3b denote a new reel and a take-up reel for supplying and winding multi-wire saw wires.

In this case, the relationship between the wire 1 for a multi-wire saw in FIG. 1, the roller 2, and the reels 3a and 3b is as follows. That is, the wire 1 is a new wire reel 3
a, a large amount is wound around the plurality of grooved rollers 2 at a predetermined pitch through a guide roller row and the like, and then wound up on a take-up reel 3b through the guide roller row and the like. The wire 1 travels in the feed direction while repeating reciprocating linear movement between the grooved rollers 2 by giving reciprocating rotational movement to the grooved rollers 2.

Hereinafter, a method of slicing the silicon ingot 6 according to the present invention will be described with reference to specific examples. First, a discard plate 8 (glass plate, carbon plate) that can be cut with a wire by an adhesive 9 (for example, NC-15K manufactured by Nikka Seiko Co., Ltd.) that can be easily removed by heating the silicon ingot 6. , Wooden board, etc.). Next, the silicon ingot 6 fixed to the discard plate 8
Is fixed to the processing fixture 7 by a clamp or the like. next,
At a traveling speed of the wire 1 of 6 to 10 m / s, a liquid (slurry) obtained by dissolving abrasive grains (for example, GC # 600) in oil from the slurry nozzle 4 is applied to the wire 1 while lowering the processing fixed table 7 at a speed of 0.3 to 0.3 m / s. Cut by cutting at 1 mm / min. The cut is made to a depth of about 2-5 mm of the discard plate.

After the completion of the cutting, the silicon wafer storage cassette 5 in which the grooves are cut at the same pitch as the grooves of the rollers 2 is slowly raised to store the wafers. It has been found that when the wire 1 is not pulled out from the processing base 7 even after the cutting, the wafer can be easily stored. At this time, it is sufficient that the wafer can be stored to some extent (for example, about 15 mm) without completely storing the wafer. Further, in order to facilitate the storage of the wafer, the processing fixing table 7 is slightly vibrated,
Can be vibrated by ultrasonic waves or the like. After the wafer storage is completed, the silicon wafer is peeled off from the discard plate 8 by heating by the heating means 10 built in the processing fixing table 7. The heating temperature is 40, depending on the adhesive 9 used.
The range of ° C to 80 ° C is appropriate, and particularly about 60 ° C for NC-15K used in Examples. Alternatively, the wire 1 may be directly heated by applying a current to the wire 1 as a heating means to separate the wire.

[0012]

As is clear from the above embodiments, according to the present invention, wafers after ingot cutting, which has been conventionally performed manually, can be automatically stored in a cassette. The cost of the slicing process can be significantly reduced, and the time of the process can be significantly reduced. The practical effect is extremely remarkable.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is a schematic explanatory view showing a cutting method using a general multi-wire saw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire 2 Roller 3a New line reel 3b Take-up reel 4 Slurry nozzle 4a Slurry 5 Storage cassette 6 Silicon ingot 7 Processing base 8 Discard plate 9 Adhesive 10 Heating means

Claims (4)

(57) [Claims] When slicing a silicon ingot adhered to a discarding plate and further fixed on a processing base, after the silicon ingot is cut , the grooved wafer storage cassette is raised to a wafer storage position. is, the fixing base may properly than it heats the pressurized cutting means, is peeled off the front Symbol bonding portion, separating the cut already wafer from the discarded plate
And, and, slicing method of the silicon ingot, characterized in that for accommodating directly the wafer separated from the plate Te該捨 the accommodating cassette. 2. A plurality of rollers which are grooved at a predetermined pitch.
One wire is wound at the predetermined pitch through the groove,
The silicon ingot is moved by the wire moving between the rollers.
Silicon ingot for slicing
In the method of slicing , the glue was attached to a discarded plate and further fixed on a fixed table for processing.
When slicing the silicon ingot,
After cutting the silicon ingot, collect wafers with grooves cut at the same pitch as the grooves of the rollers.
By raising the delivery cassette to the wafer storage position and heating the fixed base or the wire,
Peel off the adhesive and separate the cut wafer from the discard plate
And the wafer separated from the discard plate
Silicone in that it is stored directly in the set
How to slice a got. 3. The method according to claim 2, wherein the cutting means is a wire, and the wire is heated by energizing the wire.
Slicing of the silicon ingot according to claim 1
Method. 4. A cut wafer bonded to said discard plate.
Is stored in the wafer storage cassette,
It is characterized in that the fixed table for processing or the wire is vibrated.
The silicon ingot according to claim 2 or 3
Slice processing method.