Crystal ingot cutting method

Abstract

The invention belongs to the technical field of crystal processing, and provides a crystal ingot cutting method. The cutting method of the crystal ingot comprises the steps that the crystal ingot is fixed firstly, then a sectional type cutting method is adopted, cutting is conducted at different machine speeds according to different cutting depths in the cutting direction, and the whole process sequentially goes through the stages of low machine speed, high machine speed, middle machine speed, high machine speed and low machine speed. Compared with an existing cutting method using equal machine speed, the crystal ingot cutting method is suitable for cutting large-size crystal ingots, meanwhile, high-quality cutting pieces (TTV can be as low as 28 micrometers, and WARP can be as low as 22 micrometers) are obtained, and the method is simple, convenient, easy to operate and controllable, cutting time can be saved, and production efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal processing, and more specifically, to a method for cutting an ingot. Background Art

[0002] The working characteristics of semiconductor devices are limited by the basic physical properties of the materials used. Therefore, in-depth understanding of the basic physical properties of semiconductor materials and various factors that have a significant impact on these physical properties is a prerequisite for the successful manufacture of various devices. Indium phosphide is a typical III-V compound semiconductor material, which has many advantages such as high electron mobility, strong radiation resistance, good thermal conductivity, high photoelectric conversion efficiency, and wide bandgap. It is widely used in the fields of optical communication, high-frequency millimeter-wave devices, optoelectronic integrated circuits, integrated lasers, photodetectors, and high-efficiency solar cells.

[0003] The production process of indium phosphide substrates mainly includes processes such as polycrystalline synthesis, single-crystal growth, ingot cutting, grinding and polishing, and cleaning and packaging. When cutting the ingot, for the cutting of ingots with a size <6 inches, the free abrasive wire cutting method is mainly used. The high-carbon steel wire is densely arranged on the cutting roller with a fixed groove, and the roller rotates in both forward and reverse directions to drive the high-carbon steel wire to reciprocate. The cutting wire drives the abrasive (aluminum oxide, silicon carbide, etc.) to act on the crystal to be cut through the adhesion of the cutting fluid. During the cutting process, the roller and the wire mesh remain fixed in the horizontal direction, while the ingot moves perpendicular to the wire mesh at a certain table speed. This method has a stable and controllable process. For large-size (diameter ≥6 inches) indium phosphide substrates, since they are cylindrical, during cutting, the larger the diameter of the ingot, the greater the difference in the amount of worn crystal per unit vertical distance. If the cutting speed of the ingot or the wire mesh in the vertical direction is unreasonable, it is easy to cause situations such as unstable wire load, uneven crystal stress, and untimely heat dissipation, resulting in too high thickness deviation (TTV) (TTV greater than 30 μm) and warpage (WARP) (WARP greater than 30 μm) of the substrate cutting slices.

[0004] Therefore, there is an urgent need to develop a method for cutting an ingot that can obtain high-quality cutting slices with low TTV and WARP. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a method for cutting an ingot. By adopting a segmented cutting method and setting different cutting table speeds at different stages according to different cutting depths, the present invention can better cut the ingot, improve the cutting uniformity, and thus obtain high-quality substrates with lower TTV and WARP (TTV can be as low as 28 μm, and WARP can be as low as 22 μm).

[0006] The first aspect of the present invention provides a method for cutting an ingot.

[0007] Specifically, a method for cutting an ingot includes the following steps:

[0008] (1) Fix the ingot;

[0009] (2) Adopt a segmented cutting method and cut the ingot at the following table speeds according to the cutting depth:

[0010] When the cutting depth is -0.625% - 6.25% of the ingot diameter, cut at a table speed of 0.05 - 0.15 mm / min (low table speed);

[0011] When the cutting depth is 6.25% - 25% of the ingot diameter, cut at a table speed of 0.32 - 0.45 mm / min (high table speed);

[0012] When the cutting depth is 25% - 75% of the ingot diameter, cut at a table speed of 0.16 - 0.30 mm / min (medium table speed);

[0013] When the cutting depth is 75% - 93.75% of the ingot diameter, cut at a table speed of 0.32 - 0.45 mm / min (high table speed);

[0014] When the cutting depth is 93.75% - 100% of the ingot diameter, cut at a table speed of 0.05 - 0.15 mm / min (low table speed);

[0015] When the cutting depth is negative, it means that the wire mesh is not in contact with the ingot.

[0016] The term "cutting depth" in the present invention refers to: the depth at which the wire mesh cuts into the ingot during the processing, that is, starting from the wire mesh and along the cutting direction, the vertical distance connecting to the ingot. When the wire mesh and the ingot just come into contact (i.e., when a single wire mesh is tangent to the ingot), the cutting depth is "0%". Starting from the feed (tangency), the cutting depth gradually increases. The cutting depth value corresponds to the distance that the ingot moves vertically. As the ingot gradually moves upward, the cutting depth value gradually becomes larger. For example, if the ingot moves up 100 mm, the cutting position is 100 mm. Until the cut-off, the cutting depth is equal to the ingot diameter, so the maximum value of the cutting depth is equal to the ingot diameter. When the cutting depth is negative, it means that there is no contact between the wire mesh and the ingot. In the present invention, the table speed runs at 0.05 - 0.15 mm / min from the initial stage when the cutting has not started, indicating that the wire mesh needs to be started first when there is no contact with the ingot.

[0017] The present invention adopts a segmented cutting method, and sets different table speeds according to the cutting depth (the vertical distance between the wire mesh and the ingot). The whole process successively experiences the stages of low table speed - high table speed - medium table speed - high table speed - low table speed. Among them, at the time of feed (that is, when the wire mesh and the ingot just come into contact, that is, at the beginning of cutting) and at the time of cut-off (that is, when the wire mesh and the ingot are separated, that is, when cutting is completed), the table speed is relatively low; while during the process of the wire mesh traveling inside the ingot, it cuts at a relatively high table speed; the table speed near the center of the ingot is moderate and should not be too high or too low.

[0018] Preferably, the segmented cutting method is adopted, and the ingot is cut at the following table speeds according to the cutting depth:

[0019] When the cutting depth is -0.625% - 6.25% of the ingot diameter, cut at a table speed of 0.10 - 0.15 mm / min;

[0020] When the cutting depth is 6.25% - 25% of the ingot diameter, cut at a table speed of 0.35 - 0.40 mm / min;

[0021] When the cutting depth is 25% - 75% of the ingot diameter, cut at a table speed of 0.17 - 0.25 mm / min;

[0022] When the cutting depth is 75% - 93.75% of the ingot diameter, cut at a table speed of 0.35 - 0.40 mm / min;

[0023] When the cutting depth is 93.75% - 100% of the ingot diameter, cut at a table speed of 0.10 - 0.15 mm / min.

[0024] Further preferably, the segmented cutting method is adopted, and the ingot is cut at the following table speeds according to the cutting depth:

[0025] When the cutting depth is -0.625% - 6.25% of the ingot diameter, cut at a table speed of 0.10 - 0.13 mm / min;

[0026] When the cutting depth is 6.25% - 25% of the ingot diameter, cut at a table speed of 0.35 - 0.38 mm / min;

[0027] When the cutting depth is 25% - 75% of the ingot diameter, cut at a table speed of 0.17 - 0.25 mm / min;

[0028] When the cutting depth is 75% - 93.75% of the ingot diameter, cut at a table speed of 0.35 - 0.38 mm / min;

[0029] When the cutting depth is 93.75%-100% of the ingot diameter, cut at a table speed of 0.10-0.13 mm / min.

[0030] More preferably, a segmented cutting method is adopted, and according to the cutting depth, the ingot is cut at the following table speeds:

[0031] When the cutting depth is -0.625%-6.25% of the ingot diameter, cut at a table speed of 0.12-0.13 mm / min;

[0032] When the cutting depth is 6.25%-25% of the ingot diameter, cut at a table speed of 0.36-0.38 mm / min;

[0033] When the cutting depth is 25%-75% of the ingot diameter, cut at a table speed of 0.17-0.20 mm / min;

[0034] When the cutting depth is 75%-93.75% of the ingot diameter, cut at a table speed of 0.36-0.38 mm / min;

[0035] When the cutting depth is 93.75%-100% of the ingot diameter, cut at a table speed of 0.12-0.13 mm / min.

[0036] Preferably, in step (1), the ingot is adhered to a graphite bar and then fixed on the workbench.

[0037] Preferably, the height of the graphite bar is 2-10 cm.

[0038] Preferably, in step (1), the ingot is one of indium phosphide, gallium antimonide, and indium antimonide.

[0039] Preferably, in step (1), the diameter of the ingot is 6-8 inches.

[0040] Preferably, in step (2), the number of wire meshes is 50-200.

[0041] Preferably, the wire meshes are arranged parallel to each other, and / or the table speed of each wire mesh is kept consistent.

[0042] Preferably, in step (3), after cutting, cleaning is performed.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] The ingot cutting method provided by the present invention includes first fixing the ingot, and then adopting a segmented cutting method. In the cutting direction, different table speeds are set according to different cutting depths for cutting. The whole process of the present invention successively experiences stages of low table speed - high table speed - medium table speed - high table speed - low table speed, improving the cutting uniformity. Compared with the existing conventional cutting method using a constant table speed, the ingot cutting method provided by the present invention can obtain high-quality cutting wafers (TTV can be as low as 28 μm, WARP can be as low as 22 μm), and is suitable for cutting large-sized (diameter ≥ 6 inches) ingots. At the same time, the method is simple and easy to operate, controllable, can save cutting time, and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a top view of the cutting device according to Embodiment 1 of the present invention;

[0046] Figure 2 is a front view of the cutting device according to Embodiment 1 of the present invention;

[0047] Figure 3 is a schematic diagram of the positional relationship between the wire mesh and the ingot at different stages according to Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] In order to make those skilled in the art more clearly understand the technical solutions described in the present invention, the following embodiments are listed for illustration. It should be noted that the following embodiments do not limit the scope of protection required by the present invention.

[0049] In the following embodiments, the raw materials, reagents or devices used can be obtained from conventional commercial channels or can be obtained by existing known methods without special instructions.

[0050] Embodiment 1

[0051] An ingot cutting method includes the following steps:

[0052] 1. Bond the ingot (diameter 155 mm, that is, diameter 6.1 inches, length 120 mm) to the graphite bar. The height of the graphite bar is 10 cm. Then fix the ingot and the graphite bar on the multi-wire cutting machine workbench. The selected equipment is Yasunaga U-600 of Anyong, and the matching cutting wire is a high-carbon steel wire with an outer diameter of 140 μm; the number of wire meshes of the high-carbon steel wire is 150, and the wire meshes are arranged in parallel. The steel wire is fixed on the cutting roller (as Figure 1 and Figure 2 shown);

[0053] 2. Adopt a segmented cutting method. In the cutting direction, cut in the following manner according to the vertical distance between a single wire mesh and the ingot (the positional relationship between the wire mesh and the ingot at different stages from when the wire mesh and the ingot have not yet contacted, during the feed, and during the cut-off are respectively asFigure 3 As shown in A-C, during the initial cutting, the wire mesh and the ingot are not in contact, and the cutting depth is negative at this time; when just starting to feed, the cutting depth is 0 cm; when withdrawing the tool, the cutting depth reaches the maximum value, that is, equal to the diameter of the ingot):

[0054] (1) When the cutting depth is -1 - 10 mm (a cutting depth of -1 mm means that the wire mesh and the ingot are not in contact and the vertical distance is 1 mm), the cutting table speed is 0.13 mm / min;

[0055] (2) When the cutting depth is 10 - 40 mm, the cutting table speed is 0.38 mm / min;

[0056] (3) When the cutting depth is 40 - 120 mm, the cutting table speed is 0.20 mm / min;

[0057] (4) When the cutting depth is 120 - 150 mm, the cutting table speed is 0.38 mm / min;

[0058] (5) When the cutting depth is 150 - 160 mm, the cutting table speed is 0.13 mm / min;

[0059] 3. After completing the cutting, perform cleaning, and use the Corning CORNING TROPEL METROLOGY INSTRUMENTS FM200 wafer surface morphology measurement system to test the thickness deviation (TTV) and warp (WARP) of the cut wafer.

[0060] Example 2

[0061] A method for cutting an ingot, which is different from Example 1 in that the type of the ingot is replaced with a gallium antimonide ingot of the same size.

[0062] Example 3

[0063] A method for cutting an ingot, which is different from Example 1 in that in step (2), the cutting table speed is replaced as follows:

[0064] (1) When the cutting depth is -1 - 10 mm (a cutting depth of -1 mm means that the wire mesh and the ingot are not in contact and the vertical distance is 1 mm), the cutting table speed is 0.15 mm / min;

[0065] (2) When the cutting depth is 10 - 40 mm, the cutting table speed is 0.40 mm / min;

[0066] (3) When the cutting depth is 40 - 120 mm, the cutting table speed is 0.30 mm / min;

[0067] (4) When the cutting depth is 120 - 150 mm, the cutting table speed is 0.40 mm / min;

[0068] When the cutting depth is 150 - 160 mm, the cutting table speed is 0.15 mm / min.

[0069] Comparative Example 1

[0070] An ingot cutting method with a constant table speed, different from Example 1 in that in step (2), the segmented cutting method is replaced by a uniform speed cutting method, and the cutting is carried out in the following manner:

[0071] When the cutting depth is -1 - 10 mm, the cutting table speed is 0.20 mm / min;

[0072] When the cutting depth is 10 - 40 mm, the cutting table speed is 0.20 mm / min;

[0073] When the cutting depth is 40 - 120 mm, the cutting table speed is 0.20 mm / min;

[0074] When the cutting depth is 120 - 150 mm, the cutting table speed is 0.20 mm / min;

[0075] When the cutting depth is 150 - 160 mm, the cutting table speed is 0.20 mm / min.

[0076] Comparative Example 2

[0077] An ingot cutting method, different from Example 1 in that the cutting method in step (2) is different, and is specifically replaced as follows:

[0078] In the cutting direction, the following cutting is carried out according to the vertical distance between a single wire mesh and the ingot:

[0079] When the cutting depth is -1 - 10 mm, the cutting table speed is 0.13 mm / min;

[0080] When the cutting depth is 10 - 40 mm, the cutting table speed is 0.38 mm / min;

[0081] When the cutting depth is 40 - 120 mm, the cutting table speed is 0.38 mm / min;

[0082] When the cutting depth is 120 - 150 mm, the cutting table speed is 0.38 mm / min;

[0083] When the cutting depth is 150 - 160 mm, the cutting table speed is 0.13 mm / min.

[0084] Comparative Example 3

[0085] A method for cutting an ingot, which is different from Example 1 in that the cutting method in step (2) is different, and is specifically replaced as follows:

[0086] In the cutting direction, cutting is performed in the following manner according to the vertical distance between a single wire mesh and the ingot:

[0087] (1) When the cutting depth is -1 - 10 mm, the cutting table speed is 0.13 mm / min;

[0088] (2) When the cutting depth is 10 - 40 mm, the cutting table speed is 0.38 mm / min;

[0089] (3) When the cutting depth is 40 - 120 mm, the cutting table speed is 0.20 mm / min;

[0090] (4) When the cutting depth is 120 - 150 mm, the cutting table speed is 0.38 mm / min;

[0091] (5) When the cutting depth is 150 - 160 mm, the cutting table speed is 0.20 mm / min.

[0092] Product effect test

[0093] The cutting effects of each example and comparative example are shown in the following table:

[0094] Table 1 Cutting effects of each example and comparative example

[0095] Group TTV (μm) WARP (μm) Example 1 28 22 Example 2 28 24 Example 3 29 23 Comparative Example 1 31 31 Comparative Example 2 35 37 Comparative Example 3 33 36

[0096] As can be seen from the above table, by using the cutting methods of Examples 1 - 3 of the present invention, the TTV after cutting is as low as 28 - 29 μm, and the WARP is as low as 22 - 24 μm, indicating that the method of the present invention can improve the cutting uniformity and the quality of the obtained substrate.

[0097] Compared with Examples 1 - 3, the TTV and WARP levels of Example 1 are the lowest, indicating that the segmented cutting method of Example 1 has the best effect.

[0098] Comparative Example 1 uses an equal table speed cutting method. Due to the large difference in the amount of worn crystals within the unit vertical distance of the large - size ingot, there are situations such as unstable wire load, uneven crystal stress, and untimely heat dissipation, resulting in too high TTV and warpage of the substrate.

[0099] Although Comparative Examples 2 and 3 also use a segmented cutting method, Comparative Example 2 still cuts at a high table speed near the center of the circle, and Comparative Example 3 does not decelerate when the tool exits. Therefore, in Comparative Examples 2 and 3, due to incomplete release of internal stress in the crystal and stress concentration caused by cutting mechanical stress and thermal stress, the TTV of the substrate is too high and the warpage of the cutting slice is too high.

Claims

1. A method for cutting an ingot, characterized in that, It includes the following steps: (1) Fix the ingot; (2) Adopt a segmented cutting method and cut the ingot at the following table speeds according to the cutting depth: When the cutting depth is -0.625% - 6.25% of the ingot diameter, cut at a table speed of 0.05 - 0.15 mm / min; When the cutting depth is 6.25% - 25% of the ingot diameter, cut at a table speed of 0.32 - 0.45 mm / min; When the cutting depth is 25% - 75% of the ingot diameter, cut at a table speed of 0.16 - 0.30 mm / min; When the cutting depth is 75% - 93.75% of the ingot diameter, cut at a table speed of 0.32 - 0.45 mm / min; When the cutting depth is 93.75% - 100% of the ingot diameter, cut at a table speed of 0.05 - 0.15 mm / min; When the cutting depth is negative, it means that the wire mesh is not in contact with the ingot.

2. The cutting method of the ingot according to claim 1, characterized in that, Adopt a segmented cutting method and cut the ingot at the following table speeds according to the cutting depth: When the cutting depth is -0.625% - 6.25% of the ingot diameter, cut at a table speed of 0.10 - 0.15 mm / min; When the cutting depth is 6.25% - 25% of the ingot diameter, cut at a table speed of 0.35 - 0.40 mm / min; When the cutting depth is 25% - 75% of the ingot diameter, cut at a table speed of 0.17 - 0.25 mm / min; When the cutting depth is 75% - 93.75% of the ingot diameter, cut at a table speed of 0.35 - 0.40 mm / min; When the cutting depth is 93.75% - 100% of the ingot diameter, cut at a table speed of 0.10 - 0.15 mm / min.

3. The cutting method of the ingot according to claim 2, characterized in that, Adopt a segmented cutting method and cut the ingot at the following table speeds according to the cutting depth: When the cutting depth is -0.625% - 6.25% of the ingot diameter, cut at a table speed of 0.10 - 0.13 mm / min; When the cutting depth is 6.25% - 25% of the ingot diameter, cut at a table speed of 0.35 - 0.38 mm / min; When the cutting depth is 25% - 75% of the ingot diameter, cut at a table speed of 0.17 - 0.25 mm / min; When the cutting depth is 75% - 93.75% of the ingot diameter, cut at a table speed of 0.35 - 0.38 mm / min; When the cutting depth is 93.75% - 100% of the ingot diameter, cut at a table speed of 0.10 - 0.13 mm / min.

4. The cutting method of the ingot according to claim 3, characterized in that Adopt a segmented cutting method and cut the ingot at the following table speeds according to the cutting depth: When the cutting depth is -0.625% - 6.25% of the ingot diameter, cut at a table speed of 0.12 - 0.13 mm / min; When the cutting depth is 6.25% - 25% of the ingot diameter, cut at a table speed of 0.36 - 0.38 mm / min; When the cutting depth is 25% - 75% of the ingot diameter, cut at a table speed of 0.17 - 0.20 mm / min; When the cutting depth is 75%-93.75% of the ingot diameter, cut at a table speed of 0.36-0.38 mm / min; When the cutting depth is 93.75%-100% of the ingot diameter, cut at a table speed of 0.12-0.13 mm / min.

5. The cutting method of the ingot according to claim 1, wherein, In step (1), the ingot is adhered to the graphite bar and then fixed on the workbench.

6. The cutting method of the ingot according to claim 5, characterized in that, The height of the graphite bar is 2-10 cm.

7. The cutting method of the ingot according to claim 1, wherein In step (1), the ingot is one of indium phosphide, gallium antimonide, and indium antimonide.

8. The cutting method of the ingot according to claim 1, wherein, In step (1), the diameter of the ingot is 6-8 inches.

9. The cutting method of the ingot according to claim 1, characterized in that, In step (2), the number of wire meshes is 50-200.

10. The cutting method of the ingot according to claim 9, wherein, The wire meshes are arranged parallel to each other, and / or the table speed of each wire mesh is kept consistent.

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