CN111267244A - Crystal bar slicing device - Google Patents

Abstract

The invention provides a crystal bar slicing device, which comprises: a power source; an electrolytic cell for storing an electrolyte; the anode comprises a crystal bar supporting device and a crystal bar, and the crystal bar supporting device is electrically connected with the power supply and the crystal bar respectively; the cathode is accommodated in the electrolytic cell and is electrically connected with the power supply, the cathode comprises at least one linear electrode, and the linear electrode is vertically arranged relative to the axial direction of the crystal bar and is not contacted with the crystal bar; the crystal bar is positioned between the crystal bar supporting device and the cathode, and crystal bar slicing is realized through relative motion between the linear electrode and the crystal bar. According to the crystal bar slicing device and method, the kerf loss in the crystal bar cutting process is effectively reduced, meanwhile, non-contact cutting is realized, and the pollution caused by mechanical damage, wafer warping and contact cutting is effectively avoided.

Description

A crystal rod slicing device

technical field

The invention relates to the field of semiconductor manufacturing, in particular to a crystal rod slicing device.

Background technique

At present, the cutting of ingot is mainly carried out by mechanical wire cutting with steel wire driving slurry. The principle is that a high-speed moving steel wire drives the cutting blade material attached to the steel wire to rub the silicon rod, so as to achieve the cutting effect.

Since steel wire is used in the wire cutting process, it is easy to introduce contaminants such as Cu and Fe. At the same time, the wire cutting process is used to cut the ingot, and the notch loss cannot be avoided. In a typical cutting process, a kerf loss of 200 μm-250 μm is often generated, resulting in a large amount of material waste and additional costs for recycling the raw materials. At the same time, during the wire dicing process, a large amount of heat is often generated, which in turn causes the parts to expand, making it impossible to accurately control the wafer shape. The steel wire is often plated with emery grains, which often cause physical damage to the wafer. During the cutting process, as the steel wire enters and exits the crystal column, it also causes the wafer after cutting to warp.

Therefore, it is necessary to propose a new ingot slicing device and method to solve the problems in the prior art.

SUMMARY OF THE INVENTION

A series of concepts in simplified form have been introduced in the Summary section, which are described in further detail in the Detailed Description section. The Summary of the Invention section of the present invention is not intended to attempt to limit the key features and essential technical features of the claimed technical solution, nor is it intended to attempt to determine the protection scope of the claimed technical solution.

The invention provides a crystal rod slicing device, the device comprises:

power supply;

Electrolytic cells for storing electrolytes;

an anode, the anode includes a crystal rod support device and a crystal rod, and the crystal rod support device is electrically connected to the power supply and the crystal rod respectively;

a cathode, housed in the electrolytic cell and electrically connected to the power source, the cathode includes at least a linear electrode, the linear electrode is perpendicular to the axial direction of the crystal rod and is not in contact with the crystal rod ;

Wherein, the crystal rod is located between the crystal rod support device and the cathode, and the crystal rod is sliced through the relative movement between the linear electrode and the crystal rod.

Exemplarily, the ingot supporting device includes a first part and a second part, the first part is electrically connected to the power source, and the second part is a comb structure.

Exemplarily, the comb-tooth structure includes a tooth portion and a concave portion, and the linear electrodes are disposed correspondingly to the concave portion of the comb-tooth structure.

Exemplarily, the material of the ingot supporting device includes graphite, carbon-coated metal material and conductive ceramics.

Exemplarily, the cathode further includes a wire electrode guide device, used to support the wire electrode, control the distance between the wire electrode and the crystal rod, and/or drive the wire electrode to move.

Exemplarily, the material of the wire electrode and the wire electrode guide device includes carbon fiber and carbon-coated metal material.

Exemplarily, the diameter of the wire electrode is set to be 30 μm-200 μm.

Exemplarily, the diameter of the wire electrode is set to be 50 μm-75 μm.

Exemplarily, the anode includes a plurality of the wire electrodes.

Exemplarily, the number of the linear electrodes is consistent with the number of the concave portions on the comb-tooth structure.

Exemplarily, the width of the concave portion on the comb-tooth structure is set to the thickness of the wafer formed by slicing the crystal rod.

Exemplarily, the electrolyte includes hydrofluoric acid.

Exemplarily, the electrolyte also contains acetic acid.

According to the crystal rod slicing device of the present invention, the electrochemical method is used to cut the crystal rod. Compared with the mechanical cutting method using the cutting wire, the notch loss during the crystal rod cutting process is effectively reduced. The method replaces the mechanical cutting method by etching silicon, realizes non-contact cutting, and effectively avoids mechanical damage, wafer warpage and pollution caused by contact cutting. The electrochemically cut wafer does not require further processing such as chemical etching, which greatly simplifies the processing flow of the cut silicon wafer.

Description of drawings

The following drawings of the present invention are incorporated herein as a part of the present invention for understanding of the present invention. The accompanying drawings illustrate embodiments of the present invention and their description, which serve to explain the principles of the present invention.

In the attached picture:

1 is a schematic structural diagram of a device for slicing an ingot according to an embodiment of the present invention;

FIG. 2 is a schematic front view of the ingot supporting device supporting the wafer relative to the linear electrodes in FIG. 1 .

3A and 3B are schematic cross-sectional structures of the ingot supporting device in FIG. 1 taken along the A-A direction and the B-B direction, respectively.

Detailed ways

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without one or more of these details. In other instances, some technical features known in the art have not been described in order to avoid obscuring the present invention.

For a thorough understanding of the present invention, a detailed description will be set forth in the following description to illustrate the method of making the device of the present invention. Obviously, the practice of the present invention is not limited to the specific details familiar to those skilled in the semiconductor arts. Preferred embodiments of the present invention are described in detail below, however, the present invention may have other embodiments in addition to these detailed descriptions.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments in accordance with the present invention. As used herein, the singular forms are also intended to include the plural forms unless the context clearly dictates otherwise. Furthermore, it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they indicate the presence of stated features, integers, steps, operations, elements and/or components, but do not exclude the presence or Addition of one or more other features, integers, steps, operations, elements, components and/or combinations thereof.

Now, exemplary embodiments according to the present invention will be described in more detail with reference to the accompanying drawings. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It should be understood that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of these exemplary embodiments to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity, and the same reference numerals are used to denote the same elements, and thus their descriptions will be omitted.

In order to solve the technical problems in the prior art, the present invention provides a device for slicing an ingot, the device comprising:

power supply;

Electrolytic cells for storing electrolytes;

an anode, the anode includes a crystal rod support device and a crystal rod, and the crystal rod support device is electrically connected to the power supply and the crystal rod respectively;

a cathode, housed in the electrolytic cell and electrically connected to the power source, the cathode includes at least a linear electrode, the linear electrode is perpendicular to the axial direction of the crystal rod and is not in contact with the crystal rod ;

Wherein, the crystal rod is located between the crystal rod support device and the cathode, and the crystal rod is sliced through the relative movement between the linear electrode and the crystal rod.

1, FIG. 2, and FIGS. 3A and 3B, an example of a crystal rod slicing device proposed by the present invention will be described. FIG. 1 is a schematic structural diagram of a crystal rod slicing device according to an embodiment of the present invention. 2 is a schematic front view of the ingot support device supporting wafer in FIG. 1 being arranged relative to the linear electrodes, and FIGS. 3A and 3B are the cross-sectional structural schematic diagrams obtained by the ingot support device in FIG. 1 along the A-A direction and the B-B direction respectively. .

First, referring to FIG. 1 , an ingot slicing device according to an embodiment of the present invention includes a power source 100 , an electrolytic cell 200 , and an anode and a cathode connected to the positive and negative electrodes of the power source 100 , respectively.

The power source 100 can be any device that can provide DC voltage or current, such as an AC power source and an AC-to-DC device that cooperate to provide a DC voltage or current, a DC power source, etc., which is not limited herein.

The electrolytic cell 200 includes an electrolyte 201 for reacting with the silicon ingot under the action of a DC power source.

The anode includes a crystal rod 300 and a crystal rod supporting device 301 for supporting the crystal rod 300 , wherein the crystal rod supporting device 301 is electrically connected to the power source 100 and the crystal rod 300 respectively.

The cathode is housed within the electrolytic cell 200 and includes at least a linear electrode 400 . The wire electrode 400 is perpendicular to the axial direction of the crystal rod 300 , and the wire electrode 400 is not in contact with the crystal rod 300 .

Referring to FIG. 2, there is shown a schematic front view of the ingot supporting device supporting the wafer relative to the wire electrode in FIG. 1, wherein the wire electrode 400 is accommodated in the electrolyte 201 of the electrolytic cell 200, and the wire electrode 400 is opposite to the crystal. The axial direction of the rod 300 is vertical, and the wire electrode 400 is not in contact with the crystal rod 300 . In the above arrangement of the power supply, electrolysis cell, cathode and anode, the crystal rod 300 is located between the crystal rod support device 301 and the linear electrode 400 of the cathode, and is realized by the relative movement between the linear electrode 400 and the crystal rod 300 Slices of ingot 300.

Exemplarily, as shown in FIG. 1 , the cathode further includes a wire electrode guide device 401 carrying the wire electrode 400 . The wire-shaped electrode guide device 401 supports the wire-shaped electrode 400 in a tensioned state and drives the wire-shaped electrode 400 to move to the inside of the cutting position on the crystal rod 300 as the electrochemical reaction proceeds. During the process of the electrochemical reaction, the wire electrode 400 and the crystal rod 300 are not always in contact with each other. Exemplarily, the crystal rod supporting device 301 drives the crystal rod 300 to move while supporting the crystal rod 300 . As shown in FIG. 2 , the wire electrode 400 moves up and down in the electrolyte 201 in the direction indicated by the Y2 arrow, and the ingot supporting device 301 controls the ingot 300 to move up and down in the direction indicated by the Y1 arrow, so that the wire electrode 400 moves up and down in the direction indicated by the Y1 arrow. The relative movement between 400 and the crystal rod 300 is realized without contact, and finally the slicing of the crystal rod 300 is realized in the process of the electrochemical reaction. It should be understood that the manner in which the wire electrode and the crystal rod support device are used in this embodiment to control the simultaneous movement of the crystal rod and the simultaneous up-and-down movement so as to generate relative motion between the two is only exemplary, and those skilled in the art should understand that, The effect of the present invention can be achieved by single controlling the movement of the wire electrode to generate the relative movement between the wire electrode and the crystal rod, or by making the crystal rod support device control the movement of the crystal rod alone to generate the relative movement between the linear electrode and the crystal rod. At the same time, according to the setting form of the electrodes, the linear electrode or the crystal rod supporting device controls the movement of the crystal rod and is not limited to the direction of up and down movement shown in FIG. 2 in this embodiment.

Exemplarily, in the process of the electrochemical reaction, the distance between the wire electrode and the surface of the crystal rod is controlled to be consistent at all times, so as to ensure that the electrochemical cutting process has a constant rate and avoid cutting stress and wafers. warping. The material of the wire-shaped electrode guide device is set to be a non-metallic conductive material, including graphite, carbon-coated metal, and the like.

3A and 3B , which are schematic cross-sectional structural diagrams of the ingot supporting device in FIG. 1 along the A-A direction and the B-B direction. The ingot supporting device 301 is used for supporting the ingot 300 , and includes a first part 3011 and a second part 3012 , the first part 3011 is electrically connected to the power source 100 , and the second part 3012 is in contact with the ingot 300 . The first part 3011 is arranged in a strip shape, and the second part 3012 is arranged in a comb-tooth structure. Further, as shown in FIG. 1 , the second portion 3012 configured as a comb tooth structure includes a convex portion 30121 configured as a comb tooth and a concave portion 30122 located between the comb teeth. The linear electrodes 400 are arranged corresponding to the concave parts 30122 of the comb-tooth structure. During the electrolysis reaction, the part on the crystal rod 300 corresponding to the concave parts 30122 forms an anode in the electrolysis reaction corresponding to the cathode linear electrodes 400, and the concave parts 30122 correspond to The part on the crystal rod 300 is consumed by electrochemical reaction, while the part on the crystal rod 300 corresponding to the convex part 30121 does not participate in the reaction and remains, and finally forms the effect of cutting the crystal rod along the concave part on the comb-tooth structure.

Exemplarily, the material of the ingot supporting device 301 may be any non-metal conductive material. Specifically, the ingot supporting device 301 may be configured as graphite. Carbon-coated metal materials or conductive ceramics, etc.

Further, exemplarily, the crystal rod supporting device 301 and the crystal rod 300 are connected by conductive glue, so as to realize the electrical connection between the crystal rod supporting device 301 and the crystal rod 300 .

Exemplarily, the material of the wire electrode 400 can be any non-metal conductive material. Specifically, the material of the wire electrode 400 can be set to carbon fiber, carbon-coated metal wire, or the like.

Exemplarily, the electrolyte 201 includes a solution containing hydrofluoric acid. The power source applies a DC voltage or current to the anode and the cathode, and in an electrolyte containing hydrofluoric acid, the following electrochemical reaction occurs on the crystal rod on the anode:

Si→Si ⁴⁺ +4e

Si ⁴⁺ +4OH ^- →Si(OH) ₄

Si(OH) ₄ +HF→H ₂ SiF ₆ +H ₂ O

The following electrochemical reactions take place on the cathodic wire electrode:

2H ⁺ +2e→H ₂

The second part is arranged in a comb-tooth structure, so that the second part is in contact with the crystal rod to form a plurality of electrodes arranged at intervals, wherein electrochemistry occurs between the part on the crystal rod that is not in contact with the second part and the cathode formed by the linear electrode It is consumed by the reaction, and finally the part of the crystal rod that is in contact with the second part remains, forming the effect of cutting. The _H2 produced in the electrochemical reaction can be efficiently collected for other uses, reducing disposal costs.

Compared with the mechanical cutting method using a cutting wire, the electrochemical cutting method effectively reduces the notch loss during the cutting process of the crystal rod. At the same time, this method uses the electrochemical method to etch silicon instead of the mechanical cutting method. Non-contact cutting is realized, which effectively avoids mechanical damage, wafer warpage and pollution caused by contact cutting. At the same time, the electrochemically cut wafer does not need further processing such as chemical etching, which greatly simplifies the processing flow of the cut wafer.

Exemplarily, as shown in FIG. 1 , the power supply adopts a DC voltage output circuit with an adjustable voltage, and the DC voltage output by the DC voltage output circuit is applied to the anode and the cathode, wherein the applied voltage ranges is 1V-50V, preferably, the applied voltage is 5V-10V. Exemplarily, the power supply adopts a DC current output circuit with adjustable current size, and the DC output from the DC current output circuit is applied to the anode and the cathode, wherein the applied current ranges from 0.1mA to 100mA, preferably Yes, the applied current is 10mA-50mA. Using a DC voltage or current output circuit with adjustable output voltage or current, the latent heat released by the electrochemical reaction in the electrolyte can be controlled by controlling the voltage or current applied by the power source to the anode and cathode, so as to avoid the occurrence of crystal rods. Unnecessary thermal expansion to avoid residual stress after the ingot is cut into wafers.

In one example, the electrolyte is configured to include a mixture of hydrofluoric acid and acetic acid. Among them, acetic acid is used as a buffer, which can adjust the pH value of the whole electrolyte on the one hand, and increase the conductivity of the electrolyte on the other hand.

Exemplarily, referring to FIG. 2 , the width D of the protruding portion 30121 of the comb-tooth structure on the second portion 3012 is set to the thickness of the wafer formed by slicing the ingot. Exemplarily, the thickness of the silicon wafer is in the range of 750 μm-900 μm, and the width of the convex portion on the comb-tooth structure is in the range of 750 μm-900 μm. In one example, the thickness of the silicon wafer is 750 μm, and the width of the convex portion of the comb-tooth structure is 750 μm.

Exemplarily, the cathode includes a plurality of wire electrodes, and the number of wire electrodes is increased, so that the plurality of wire electrodes can cut the crystal rod at the same time, thereby improving the efficiency of cutting the crystal rod. Exemplarily, the number of the wire electrodes is consistent with the number of comb teeth on the comb structure, so as to maximize the efficiency of cutting the ingot.

Exemplarily, the diameter of the wire electrode is set to be 30 μm-200 μm. The reduction of the diameter of the wire electrode can effectively reduce the notch loss generated in the process of electrochemically cutting the crystal rod. Preferably, the diameter of the wire electrode is set to be 50 μm-75 μm, which can ensure the strength of the wire electrode while reducing the notch loss. In one example, using a wire electrode with a diameter of 50 μm, the kerf loss caused by cutting the ingot is reduced from 200 μm-250 μm generated by existing mechanical cutting to 75 μm. In the present invention, since the method of electrochemical non-contact cutting of the crystal rod is adopted, there is no mechanical effect on the wire electrode. Compared with the cutting wire in mechanical cutting, there is no risk of wire breakage, and the service life of the wire electrode is greatly improved.

To sum up, according to the crystal rod slicing device of the present invention, the electrochemical method is used to cut the crystal rod. Compared with the mechanical cutting method using the cutting wire, the notch loss during the crystal rod cutting process is effectively reduced, and at the same time , Electrochemical method is used to etch silicon instead of mechanical cutting method to realize non-contact cutting, which effectively avoids mechanical damage, wafer warpage and pollution caused by contact cutting. The electrochemically cut wafer does not need to be further processed such as chemical etching, which greatly simplifies the wafer processing process.

The present invention has been described by the above-mentioned embodiments, but it should be understood that the above-mentioned embodiments are only for the purpose of illustration and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above-mentioned embodiments, and more variations and modifications can also be made according to the teachings of the present invention, and these variations and modifications all fall within the protection claimed in the present invention. within the range. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (12)

1. a crystal rod slicing device, is characterized in that, comprises: power supply; Electrolytic cells for storing electrolytes; an anode, the anode includes a crystal rod support device and a crystal rod, and the crystal rod support device is electrically connected to the power supply and the crystal rod respectively; a cathode, housed in the electrolytic cell and electrically connected to the power source, the cathode includes at least a linear electrode, the linear electrode is perpendicular to the axial direction of the crystal rod and is not in contact with the crystal rod ; Wherein, the crystal rod is located between the crystal rod support device and the cathode, and the crystal rod is sliced through the relative movement between the linear electrode and the crystal rod. 2 . The ingot slicing device according to claim 1 , wherein the ingot supporting device comprises a first part and a second part, the first part is electrically connected to the power supply, and the second part is 2 . Comb structure. 3 . The ingot slicing device according to claim 2 , wherein the comb-tooth structure comprises a tooth portion and a concave portion, and the linear electrodes are arranged corresponding to the concave portion of the comb-tooth structure. 4 . 4. The ingot slicing device according to claim 1, wherein the material of the ingot supporting device comprises graphite, carbon-coated metal materials and conductive ceramics. 5. The crystal rod slicing device according to claim 1, wherein the cathode further comprises a linear electrode guide device for supporting the linear electrode and controlling the distance between the linear electrode and the crystal rod. and/or drive the wire electrodes to move. 6 . The ingot slicing device according to claim 5 , wherein the material of the wire electrode and the wire electrode guide device comprises carbon fiber and carbon-coated metal material. 7 . 7 . The ingot slicing device according to claim 1 , wherein the diameter of the wire electrode is set to be between 30 μm and 200 μm. 8 . 8 . The ingot slicing device according to claim 7 , wherein the diameter of the wire electrode is set to be between 50 μm and 75 μm. 9 . 9 . The ingot slicing device according to claim 3 , wherein the number of the linear electrodes is the same as the number of the concave portions of the comb-tooth structure. 10 . 10 . The crystal rod slicing device according to claim 2 , wherein the width of the convex portion on the comb-tooth structure is set to the thickness of the wafer formed after the crystal rod is sliced. 11 . 11. The ingot slicing apparatus of claim 1, wherein the electrolyte comprises hydrofluoric acid. 12. The ingot slicing device according to claim 11, wherein the electrolyte further contains acetic acid.

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