JPH0936080A - Method for washing machined silicon ingot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an expensive washing liquid from quickly deteriorating and at the same time facilitate liquid control when feeding a machined silicon ingot whose cutting process for forming a wafer is completed to a chemical liquid washing process for washing. SOLUTION: Pressed hot water is ejected from nozzles 12a-12g to a machined silicon ingot 2 whose cutting process for forming a plurality of wafers is completed, the slurry inside a narrow slits in the ingot 2 and in a carbon block 4 is eliminated, and then the ingot 2 is fed to a chemical liquid washing process for washing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a processed silicon ingot, and more particularly to a method for cleaning a silicon ingot which has been subjected to a cutting process for forming a plurality of wafers.

[0002]

2. Description of the Related Art As is well known, a wafer is, for example, a silicon ingot which is a circular rod-shaped body having a certain length and is, for example, 880 μm.
It is formed by cutting it to a certain thickness such as
The silicon ingot is set in the cutting processing part in a state in which it is held through the cutting attachment jig and the carbon block (see FIG. 1), and is generally cut with a wire saw, and the processed silicon that has finished this cutting step is processed. The ingot is sent as it is to the chemical solution cleaning step of the subsequent step for cleaning.

[0003]

However, the cutting abrasive powder, oil, etc. used in the cutting process adheres to a narrow cutting slit of 250 μm, for example.
This is transferred to the chemical cleaning process, which increases the load here and deteriorates the expensive cleaning liquid in a short period (or a short time), so the amount of cleaning liquid used increases and the cost reduction is hindered. Management was troublesome.

In view of these drawbacks, the present invention has conducted extensive studies to solve them, and as a result, the silicon ingot, which has undergone the cutting process for forming a wafer, is not directly sent to the chemical cleaning process for cleaning. By spraying with warm water and then sending it to the chemical cleaning step for cleaning,
It has been found that deterioration of an expensive cleaning liquid can be prevented for a short period of time, cost can be reduced, and liquid management can be facilitated.

[0005]

That is, in the method for cleaning a processed silicon ingot according to the present invention, the silicon ingot, which has undergone the cutting process for forming a plurality of wafers, is held on the cutting attachment jig. It is characterized in that the chemical solution is washed after being sprayed with hot water in the form of. A wire saw is preferably used in the cutting step.

[0006]

EXAMPLE In FIG. 1, a silicon ingot which has been subjected to a cutting process for forming a wafer, that is, a silicon ingot which is a circular rod-shaped body having a certain length is fixed with a wire saw to a certain thickness (for example, 880 μm). A processed silicon ingot 2 which is cut into a plurality of wafers 1 is shown. The ingot 2 is adhered and held to a carbon block 4 adhered to a cutting attachment jig 3. .

The cutting attachment jig 3 is used to set the silicon ingot to be cut at the processing portion, and the carbon block 4 is used for cutting the silicon ingot with a wire saw. This is for preventing the cutting attachment jig 3 from being damaged.

A narrow (for example, 250 μm) cutting slit 5 is formed in the processed silicon ingot 2 and the carbon block 4. Here, cutting abrasive powder, oil, etc. used for cutting (hereinafter, Slurry) is attached. The slurry is highly viscous and adheres deep inside the narrow cutting slit 5.

Therefore, if this adhered slurry is carried to a chemical solution cleaning step as a subsequent step, the cleaning solution is easily deteriorated. Therefore, in the present invention, this is pre-washed, that is, washed with hot water and sent to the chemical cleaning step.

2 and 3 show such a hot water spray cleaning mode, FIG. 2 is a front view and FIG. 3 is a left side view of FIG. In both figures, the processed silicon ingot 2 that has undergone the cutting step for forming the wafer 1 is
Workers carry it to the hot water spray cleaning device as it is. Then, the worker places the processed silicon ingot 2 on the transfer table 7 provided in the hot water spray cleaning device, and pushes the table 7 to move it to the hot water spray cleaning unit A.

Then, the processed silicon ingot 2 is lifted up and locked to the upper left and right clamps 8. The processed silicon ingot 2 is attached to the cutting attachment jig 3
The clamp 8 is attached to the apparatus frame 10 so that the clamp 8 can be swung by the air cylinder 9.

Therefore, as shown in FIG. 4, when both clamps 8 are horizontally positioned,
The processed silicon ingot 2 is locked to it, and then, as shown in FIG. 5, both clamps 8 are swung so that the clamps 8 project upward, so that the processed silicon ingot 2 has its lower end Transfer table 7
Can be set to be located above.

In the following, if the processed silicon ingot 2 can be set in the washing section A by spraying hot water,
After the transfer table 7 is returned to the original position from here, the switching valve 11 is controlled to a predetermined value, and the nozzle 12
Hot water is sprayed onto the processed silicon ingot 2 from the group.

At this time, hot water is supplied from a hot water tank 14 via a high-pressure pump 13, and this tank 14 is
It is equipped with a heater, liquid thermometer, liquid level gauge, etc., and stores a certain amount of hot water at around 60 ° C. Further, when the arm 15 to which the group of nozzles 12 is attached is moved to the right side in FIG. 2 and moved to the position 15a shown by the chain double-dashed line, it is moved to the left side. It is reciprocated a predetermined number of times. This movement control is performed by the movement device 16.

The moving device 16 includes a slide base 21 engaged with a pair of rails 20 mounted on the device frame 10, as shown in an enlarged view in FIG. By controlling the movement with, the arm 15 suspended therein can be moved to a predetermined position.

The slide base 21 is a motor 22.
Is engaged with the endless chain 24 that is stretched over the drive-side chain wheel 23a on which is mounted and the driven-side chain wheel 23b on the opposite side thereof.
2 is reciprocated in the left-right direction by the forward / reverse rotation control, and at that time, the forward / reverse rotation control of the motor 22 is performed by obtaining a predetermined control signal from the sensors 25a and 25b. In addition, by selecting the cleaning stroke corresponding to the length of the ingot, it is possible to save the amount of water used.

On the other hand, hot water is jetted from the group of nozzles 12 mounted on the arm 15 which is reciprocated in this way. This aspect is shown in FIGS. In both figures, seven nozzles 12a to 12g are shown, but first, the upper nozzles 12a and 12b are sprayed,
Then, after the arm 15 reciprocates left and right a predetermined number of times, it is jetted from 12c below it.

Similarly, subsequently, the nozzles 12d, 1
After being ejected from 2e, finally, the nozzles 12f, 12g
Injected from. By such injection, it is possible to sequentially remove the attached slurry from the upper side and allow it to flow down, so that the cleaning can be effectively performed.

The hot water sent through the switching valve 11 is pressurized.
0a, 30b, 30c are sent to each nozzle 12a-g. In addition, the pipeline 2 in which the nozzles 12a to 12g are mounted
6a, 26b, 27a, 27b and 28 are fixtures 3
It is attached to the arm 15 via 1, 32a, 32b, 33, 34.

Further, the sewage flowing down from the processed silicon ingot 2 is stored in the waste water tank 36 via the tray 35 (see FIG. 3). When the above-mentioned pre-cleaning is completed, the empty transfer table 7 is warmed. The machined silicon ingot 2 is removed and placed on the transfer table 7 with the clamps 8 moved horizontally to the spray cleaning section A, and both clamps 8 are positioned horizontally, and it is returned from here to the original position. This is done by the worker.

Next, the pre-cleaned processed silicon ingot 2 is sent to the subsequent chemical liquid cleaning step for cleaning while being held by the cutting attachment jig 3. that time,
By such pre-cleaning, the slurry adhering to the cutting process is sufficiently removed, so that the load of the chemical cleaning process can be reduced, and therefore the expensive cleaning liquid containing a surfactant, special oil, etc. can be used for a short period of time. It is possible to prevent deterioration in a short time (or a short time), and it is possible to reduce cost and facilitate liquid management.

The cutting process as a premise is, for example, the case of using a wire saw which is heavily contaminated with oil and forms a narrow cutting gap. The processed silicon ingot 2 which has undergone such cutting process is used. This effect of pre-washing, that is, washing with hot water is remarkable.

The nozzles 12a to 12g used for hot water spray cleaning are preferably fan-shaped rather than cone-shaped because the hot water is sprayed into the narrow cutting slit 5, and the spray angle is generally Specifically, it may be set to 90 °, but the present invention is not limited to this, and is appropriately selected from the range of 60 ° to 120 ° in consideration of the number of nozzles mounted and the like.
Further, it is preferable that the distance from the hot water spray surface is as close as possible. If this distance is long, the jet flow spreads and the water force deteriorates, making it difficult to obtain a sufficient cleaning effect.

The mounting angle of the nozzles 12a to 12g is 30 ° to 60 ° downward considering the flow of the slurry.
It is preferable to mount it so that it can be adjusted to a predetermined angle within the range of 10 to 30 kg / cm ² , and the pressurized hot water sprayed onto the processed silicon ingot 2 or the like is
It is preferable to control the temperature to about 40 to 60 ° C., and the spraying amount is preferably 5 to 10 L / min per nozzle.

The processed silicon ingot 2 which has been subjected to the chemical cleaning step is separated from the carbon block 4, which is immersed in a 3 to 5% acetic acid aqueous solution at 60 ° C. to dissolve the adhesive. Done. After that, in a separate process, the cutting attachment jig 3 is separated from the carbon block 4, and the block 4 is discarded and the cutting attachment jig 3 is reused.

[0026]

As described above, according to the first and second aspects of the present invention, the slurry adhering to the silicon ingot can be effectively removed in the cutting step for forming the wafer, which is the chemical solution in the subsequent step. It is possible to prevent it from being carried to the cleaning process, and thus the load of the chemical cleaning process can be reduced, and an expensive cleaning liquid containing a surfactant or special oil can be used for a short period (or short time). It is possible to prevent deterioration due to the above, and it is possible to reduce the cost and also to facilitate the liquid management.

[Brief description of drawings]

FIG. 1 is a diagram showing a manner of holding a processed silicon ingot.

FIG. 2 is a front view of a pre-cleaning device.

FIG. 3 is a left side view of FIG. 2;

FIG. 4 is a view showing a support mode of a processed silicon ingot.

FIG. 5 is a view showing a support mode during cleaning of a processed silicon ingot.

FIG. 6 is a front view of a moving device that reciprocates an arm on which a nozzle group is mounted.

FIG. 7 is a front view showing how the nozzle group is attached to the arm.

FIG. 8 is a right side view of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer 2 Processed silicon ingot 3 Mounting jig for cutting 4 Carbon block 5 Cutting slit 12a-12g Nozzle 13 High pressure pump 14 Hot water tank

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Keiichi Takami 2-20, Ekimae-dori, Utsunomiya-shi, Tochigi No. 507 Heights, Ekimae-dori (72) Inventor Ryoichi Kawamura 4845 Mishima City, Shizuoka Toray Engineering Co., Ltd. Company (72) Inventor Takehiro Watanabe Toray Engineering Co., Ltd., 4845 Mishima City, Shizuoka Prefecture (72) Masahiro Kosako 4845 Toray Engineering Co., Ltd., Mishima City, Shizuoka Prefecture

Claims (2)

[Claims] 1. A process characterized in that a silicon ingot that has undergone a cutting process for forming a plurality of wafers is washed by being sprayed with hot water while being held on a cutting attachment jig, and then cleaned with a chemical solution. Cleaning method for used silicon ingot. 2. The method for cleaning a processed silicon ingot according to claim 1, wherein a wire saw is used in the cutting step.