Directional multi-line slicing method for irregular single crystal ingot

Abstract

The invention provides a directional multi-wire slicing method for an irregular single crystal ingot. The method comprises the following steps: S1, directionally cutting a cutting end face parallel to a target crystal orientation plane from the irregular single crystal ingot; s2, filling and shaping the single crystal ingot cut in the step S1 to obtain a single crystal shaping body with a regular shape, and exposing the cut end surface outside; s3, orienting the single crystal complementary body, and carrying out multi-line slicing to obtain a plurality of cutting blades; and S4, removing the complementary material on the cutting sheet to obtain the wafer. According to the method, the regular-shaped structure beneficial to multi-line slicing processing is formed for the irregular single-crystal ingot in a filling mode, so that the irregular single-crystal ingot can be cut into a plurality of wafers conforming to the target crystal orientation at a time, the loss of crystal materials can be obviously reduced, and the processing period is obviously shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal cutting, and in particular relates to a directional multi-wire slicing method for irregular single crystal ingots. Background Art

[0002] With the rapid development of information technology, semiconductor materials are widely used in many fields such as integrated circuits, power devices and optoelectronic devices. Cadmium zinc telluride (CZT) is the best substrate material for the MCT epitaxial layer in mercury cadmium telluride (MCT) infrared detectors. CZT wafers are made from CZT single crystals through directional cutting. The processing efficiency and yield of the ingot have an important impact on the cost of the wafer.

[0003] Since the directional growth technology of CZT single crystal is difficult, most CZT single crystals are selected and cut from the irregular single crystal area of ​​the grown CZT polycrystalline ingot. At present, the inner circle cutting method is mostly used for irregular crystal materials, but the edge of the inner circle blade is thicker (350um), which makes the loss of wafer cutting (about 400um) larger, which greatly wastes the expensive crystal material; in addition, the inner circle cutting is a single-piece processing. Taking the length of 60mm as an example, it takes about one week to complete the processing, and the processing cycle is relatively long. Summary of the invention

[0004] The object of the present invention is to provide a method for directional multi-wire slicing of irregular single crystal ingots, which can at least solve some of the defects existing in the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A method for directional multi-line slicing of irregular single crystal ingots, comprising the following steps:

[0007] S1. Directively cut an irregularly shaped single crystal ingot to obtain a cut end face parallel to a target crystal orientation plane;

[0008] S2, filling and reshaping the single crystal ingot cut in step S1 to obtain a single crystal reshaping body of regular shape, and leaving the cut end surface exposed;

[0009] S3, orienting the single crystal complement, performing multi-line slicing, and obtaining a plurality of cut slices;

[0010] S4. Remove the complementary material on the cutting piece to obtain a wafer.

[0011] Furthermore, in the step S1, an inner circle slicer is used to directionally cut the cutting end face of the single crystal ingot.

[0012] Furthermore, in step S2, the filling and molding process for the irregular-shaped single crystal ingot is as follows: the cut end face of the irregular-shaped single crystal ingot is placed on a platform with its face downward, the single crystal ingot is framed with a regularly-shaped hollow tube, and a filling material is poured between the single crystal ingot and the hollow tube. After the filling material solidifies and forms, it is bonded to the inner wall of the hollow tube and the single crystal ingot to form a whole, thereby obtaining a regularly-shaped single crystal molding body.

[0013] Furthermore, an isolation layer is provided between the cutting end surface and the platform.

[0014] Furthermore, the filling material is a mixture of gypsum powder and water in a mass ratio of 5:1 to 2:1 or epoxy resin AB glue.

[0015] Furthermore, before the irregularly shaped single crystal ingot is filled with a supplementary mold, a layer of buffer material is coated on the remaining surface of the single crystal ingot except the cut end surface.

[0016] Furthermore, the solidification shrinkage rate of the buffer material is no more than 1%.

[0017] Furthermore, the hollow cylinder is a thin-walled graphite cylinder.

[0018] Furthermore, in step S3, the single crystal complement is oriented in the following way: the single crystal complement is clamped on an X-ray orientation bonding instrument with the cut end facing outward, X-rays are used to detect the crystal orientation of the cut end and adjust the position of the single crystal complement so that the cut end of the single crystal complement is parallel to the wire mesh of the multi-wire slicer.

[0019] Furthermore, in step S4, the repairing material on the cutting piece is removed by heating with clean water.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The directional multi-wire slicing method for irregular single crystal ingots provided by the present invention forms a regular shape structure that can be processed by a multi-wire slicing method by filling and filling the irregular single crystal ingot. At the same time, the cut end face parallel to the target crystal orientation plane obtained by pre-cutting is exposed to the outside, which is conducive to positioning using X-ray directional equipment. Therefore, the irregular single crystal ingot can be cut into multiple chips that meet the target crystal orientation at one time. This method can significantly reduce the loss of crystal material and significantly shorten the processing cycle.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the filling and filling structure of the irregular single crystal ingot in an embodiment of the present invention;

[0024] Figure 2Schematic diagram of the structure of a single crystal filler after filling the filler in an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of multi-line slices of a single crystal complement body according to an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of the cut piece obtained after slicing in an embodiment of the present invention.

[0027] Explanation of the accompanying reference numerals: 1. platform; 2. isolation layer; 3. single crystal ingot; 4. buffer material; 5. filling material; 6. hollow cylinder; 7. single crystal complementary mold; 8. multi-wire slicer wire mesh. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integral connection; for ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances; in the description of the present invention, unless otherwise specified, "multiple" and "several" mean two or more.

[0031] like Figures 1 to 4 As shown, this embodiment provides a method for directional multi-line slicing of irregular single crystal ingots, comprising the following steps:

[0032] S1. Orienting and cutting an irregularly shaped single crystal ingot 3 to obtain a cutting end face parallel to a target crystal orientation plane.

[0033] Specifically, after the crystal growth is completed, the single crystal area that needs to be sliced ​​(i.e., the irregularly shaped single crystal ingot 3) is selected and cut, and an inner circle slicer is used to directionally cut the cutting end face of the single crystal ingot 3 parallel to the target crystal orientation plane; taking CZT single crystal as an example, an inner circle slicer is used to directionally cut the (111) crystal orientation plane of the CZT single crystal.

[0034] S2, filling and supplementing the single crystal ingot 3 cut in the above step S1 to obtain a single crystal supplementary body 7 of regular shape, and leaving the cut end surface exposed.

[0035] In some embodiments, a specific filling method is as follows Figure 1 As shown, the cut end face of the irregularly shaped single crystal ingot 3 is placed on the platform 1 facing downward, the single crystal ingot 3 is framed by a regularly shaped hollow cylinder 6, and a filling material 5 is poured between the single crystal ingot 3 and the hollow cylinder 6. After the filling material 5 solidifies and forms, it is bonded to the hollow cylinder 6 and the single crystal ingot 3 as a whole, so as to obtain a regularly shaped single crystal complement 7, as shown in FIG. Figure 2 shown.

[0036] Specifically, the hollow cylinder 6 can be made of but not limited to a thin-walled graphite cylinder, and the filling material 5 is made of a solidifying material with a small solidification shrinkage rate and good fluidity. For example, the filling material 5 can be made of epoxy resin AB glue, or a mixture of gypsum powder and water in a mass ratio of 5:1 to 2:1.

[0037] Preferably, in order to avoid abrasion between the cut end face of the single crystal ingot 3 and the platform 1, and to prevent the filling material 5 from being bonded to the platform 1 after solidification, an isolation layer 2 may be placed on the platform 1, and the cut end face of the single crystal ingot 3 is placed downward on the isolation layer 2, and the hollow cylinder 6 and the filling material 5 are also placed on the isolation layer 2. The material of the isolation layer 2 is selected based on the principle of not damaging the cut end face and being easy to separate from the filling material 5.

[0038] Preferably, before filling the single crystal ingot 3 with a filler mold, a layer of buffer material 4 is coated on the remaining surface of the single crystal ingot 3 except the cut end surface to prevent the single crystal ingot 3 from being torn due to the solidification shrinkage of the filling material 5. Specifically, the buffer material 4 is selected from a material with a solidification shrinkage rate of no more than 1%, and the buffer material 4 can be selected from but not limited to epoxy resin AB glue, preferably a material with a solidification shrinkage rate close to 0; and the buffer material 4 is designed to be coated with a thickness of 0.5 to 3 mm.

[0039] S3, orienting the single crystal supplementary mold body 7 after the filling supplementary mold in step S2, and performing multi-line slicing to obtain a plurality of cut pieces.

[0040] Since the irregularly shaped single crystal ingot 3 is formed into a single crystal complement body 7 with a regular shape structure after filling and complementing, it is easier to orient and fix the regular shape structure, and it can be sliced ​​using a multi-line slicing processing method.

[0041] Specifically, a single crystal complement 7 of a regular shape is clamped on an X-ray orientation bonding instrument with the cut end surface facing outward, and the crystal orientation of the cut end surface is detected by X-rays and the relative position of the single crystal complement 7 is adjusted so that the cut end surface of the single crystal complement 7 is parallel to the end surface of the multi-line slicing plate of the multi-line slicer, and then the two are bonded together using an adhesive, and then the position of the multi-line slicing plate is adjusted so that the end surface of the multi-line slicing plate is parallel to the wire mesh 8 of the multi-line slicer, thereby ensuring that the cut end surface is parallel to the wire mesh of the multi-line slicer, as shown in FIG. Figure 3 As shown; start the multi-wire cutting machine to cut, so as to obtain a number of cutting pieces. The structure of the cutting piece is as follows Figure 4 As shown, the middle is the desired wafer, and the outer periphery of the wafer is the complementary material (including buffer material 4, filling material 5 and hollow cylinder wall 6).

[0042] S4. Remove the complementary material on the cutting piece to obtain a wafer.

[0043] Specifically, a specific method for removing the repair material on the cutting piece is to use clean water to heat it. For example, when the filling material 5 in the above embodiment is epoxy resin AB glue, or a mixture of gypsum powder and water, the repair material on the cutting piece can be removed by placing the cutting piece in 65-degree clean water for 30 minutes.

[0044] Optionally, a cadmium zinc telluride (CZT) wafer may be processed from an irregular CZT single crystal by the directional multi-wire slicing method of this embodiment.

[0045] Moreover, compared with the existing inner circle cutting machine that cuts chips one by one, the directional multi-line slicing method of this embodiment can reduce the crystal material loss of single chip cutting from 400um to 120um, thereby reducing the loss of crystal material. At the same time, the cutting cycle of irregular single crystals with a length of 60mm is shortened from one week to one day, greatly shortening the processing cycle.

[0046] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A method for directional multi-wire slicing of irregular single crystal ingots, characterized in that: The steps include: S1. Directively cut an irregularly shaped single crystal ingot to obtain a cut end face parallel to a target crystal orientation plane; S2, filling and reshaping the single crystal ingot cut in step S1 to obtain a single crystal reshaping body of regular shape, and leaving the cut end surface exposed; S3, orienting the single crystal complement, performing multi-line slicing, and obtaining a plurality of cut slices; S4. Remove the complementary material on the cutting piece to obtain a wafer.

2. The directional multi-wire slicing method for irregular single crystal ingots according to claim 1, characterized in that: In the step S1, an inner circle slicer is used to directionally cut the cut end face of the single crystal ingot.

3. The directional multi-wire slicing method for irregular single crystal ingots according to claim 1, characterized in that: In step S2, the filling and molding process for the irregular-shaped single crystal ingot is as follows: the cut end face of the irregular-shaped single crystal ingot is placed on a platform with its face downward, the single crystal ingot is framed with a regularly shaped hollow tube, and a filling material is poured between the single crystal ingot and the hollow tube. After the filling material solidifies and forms, it is bonded to the inner wall of the hollow tube and the single crystal ingot to form a whole, thus obtaining a regularly shaped single crystal molding body.

4. The directional multi-wire slicing method for irregular single crystal ingots according to claim 3, characterized in that: An isolation layer is provided between the cutting end surface and the platform.

5. The directional multi-wire slicing method for irregular single crystal ingots according to claim 3, characterized in that: The filling material is a mixture of gypsum powder and water in a mass ratio of 5:1 to 2:1 or epoxy resin AB glue.

6. The directional multi-wire slicing method for irregular single crystal ingots according to claim 3, characterized in that: Before the irregularly shaped single crystal ingot is filled with a mold, a layer of buffer material is coated on the remaining surface of the single crystal ingot except the cut end surface.

7. The directional multi-wire slicing method for irregular single crystal ingots according to claim 6, characterized in that: The solidification shrinkage rate of the buffer material is no more than 1%.

8. The directional multi-wire slicing method for irregular single crystal ingots according to claim 3, characterized in that: The hollow cylinder is a thin-walled graphite cylinder.

9. The directional multi-wire slicing method for irregular single crystal ingots according to claim 1, characterized in that: In the step S3, the single crystal complement is oriented as follows: the single crystal complement is clamped on an X-ray orientation bonding instrument with the cut end facing outward, the crystal orientation of the cut end is detected by X-rays and the position of the single crystal complement is adjusted so that the cut end of the single crystal complement is parallel to the wire mesh of the multi-wire slicer.

10. The directional multi-wire slicing method for irregular single crystal ingots according to claim 1 or 3, characterized in that: In step S4, the repairing material on the cutting piece is removed by heating with clean water.

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