Quartz crucible containing bubble structure and preparation method thereof

Abstract

The invention provides a preparation method of a quartz crucible containing a bubble structure. The preparation method comprises the step of performing laser internal engraving on the outer layer of a fused and molded quartz crucible blank to prepare the bubble structure. According to the preparation method, digital regulation and control of the bubble structure in the bubble layer of the quartz crucible can be realized by adjusting laser parameters, the distribution uniformity of bubbles is improved, and the problem of uneven radiation of the quartz crucible is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of single crystal silicon preparation, and relates to a quartz crucible with a bubble structure and a preparation method thereof. Background Art

[0002] The quartz crucible is an important auxiliary part for pulling single crystal silicon rods by the Czochralski method (CZ method). The quartz crucible plays an irreplaceable role as a carrier for silicon materials. In the process of preparing silicon single crystals by the CZ method, the quartz crucible serves to hold polycrystalline silicon blocks and powders, polycrystalline silicon melts, as well as for heat conduction and heat field control. The performance of the quartz crucible plays a crucial role in the output of single crystal silicon.

[0003] To meet the production requirements of high-quality single crystal silicon, the quartz crucible usually consists of an outer bubble layer and an inner transparent layer. The inner layer directly contacts the silicon melt, and the outer bubble layer contacts the graphite crucible. It is necessary to evenly scatter the heat from the heater, so a specified number and size of bubbles are required to uniformly heat the silicon melt. During the preparation process of the quartz crucible, the preparation defects of the bubble layer will directly affect the production cost and product quality of single crystal silicon. If the bubble layer is not properly prepared, it may lead to uneven growth of single crystal silicon, thereby affecting its electrical and mechanical properties. Therefore, the preparation of a crucible bubble layer that can digitally control the number, size, high temperature resistance, anti-crystallization, and pollution-free has become an urgent problem to be solved in this field.

[0004] In summary, during long-term and high-temperature use, the bubbles on the outer layer of the quartz crucible will expand and burst, and crystallization will form, thereby affecting the crystal pulling process. Summary of the Invention

[0005] To solve the technical problems existing in the prior art, the present invention provides a quartz crucible with a bubble structure and a preparation method thereof. This preparation method can digitally control the bubble structure in the quartz crucible by adjusting laser parameters, improve the uniformity of bubble distribution, and avoid the problem of uneven radiation of the quartz crucible.

[0006] To achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] One of the purposes of the present invention is to provide a preparation method for a quartz crucible with a bubble structure, which includes laser internal engraving on the outer layer of the formed quartz crucible blank to prepare a bubble structure.

[0008] As a preferred technical solution of the present invention, the laser in the laser internal engraving is any one or a combination of at least two wavelengths of lasers such as green laser with a wavelength of 510 - 550 nm, infrared laser with a wavelength of 1000 - 1050 nm, or ultraviolet laser with a wavelength of 340 - 360 nm.

[0009] As a preferred technical solution of the present invention, the power of the laser in internal laser engraving is 1-30 W.

[0010] As a preferred technical solution of the present invention, the focal length of the laser in internal laser engraving is 100-110 mm.

[0011] As a preferred technical solution of the present invention, the spot diameter of the laser in internal laser engraving is 0.01-0.2 mm.

[0012] As a preferred technical solution of the present invention, the preparation method of the quartz crucible blank includes mold forming, melting forming, cooling and demolding carried out in sequence.

[0013] As a preferred technical solution of the present invention, mold forming includes substrate forming and functional layer forming carried out in sequence.

[0014] As a preferred technical solution of the present invention, sandblasting treatment is carried out before demolding.

[0015] As a preferred technical solution of the present invention, after internal laser engraving, the quartz crucible blank is cleaned and barium-coated.

[0016] The second object of the present invention is to provide a quartz crucible with a bubble structure, and the quartz crucible with a bubble structure is prepared by the preparation method of the quartz crucible with a bubble structure provided by the first object of the present invention.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] (1) The present invention provides a quartz crucible with a bubble structure and a preparation method thereof. The preparation method can realize digital control of the bubble structure in the bubble layer of the quartz crucible by adjusting the laser parameters.

[0019] (2) The present invention provides a quartz crucible with a bubble structure and a preparation method thereof. The preparation method can improve the uniformity of the distribution of bubbles in the bubble layer of the quartz crucible and avoid the problem of non-uniform radiation of the quartz crucible. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic flow chart of a preparation method of a quartz crucible with a bubble structure provided for the specific embodiment of the present invention.

[0021] The following further describes the present invention in detail. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the patent protection of the present invention. The scope of protection of the present invention is subject to the claims. SPECIFIC EMBODIMENTS

[0022] The following further illustrates the technical solutions of the present application through specific embodiments.

[0023] A specific embodiment of the present invention provides a method for preparing a quartz crucible with a bubble structure, which includes laser internal engraving on the outer layer of the quartz crucible blank after melting and forming to prepare the bubble structure.

[0024] In the present invention, laser internal engraving on the outer layer of the quartz crucible blank can form a new bubble structure in the bubble layer or adjust the existing bubble structure. The laser emitter generates a focused laser beam, which is adjusted and focused by the optical system to form a high-energy laser beam. The high-energy laser pulse is focused inside the quartz material. When the light intensity at the focus is much higher than the damage threshold of the material, it will cause local heating and cracking of the material, forming microcracks and microvoids ranging from micrometers to millimeters, thereby realizing the digital control of the bubble structure in the bubble layer of the quartz crucible and improving the uniformity of the bubble distribution in the bubble layer of the quartz crucible.

[0025] In a specific embodiment of the present invention, the laser in the laser internal engraving is any one or a combination of at least two wavelengths of laser, such as green laser with a wavelength of 510 - 550 nm, infrared laser with a wavelength of 1000 - 1050 nm, or ultraviolet laser with a wavelength of 340 - 360 nm, etc., and preferably a green laser with a wavelength of 510 - 550 nm.

[0026] In a specific embodiment of the present invention, the power of the laser in the laser internal engraving is 1 - 30 W, such as 1 W, 2 W, 5 W, 10 W, 15 W, 20 W, 25 W, or 30 W, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0027] In a specific embodiment of the present invention, the power of the laser should be controlled within a certain range. If the laser power is too small, it cannot reach the damage threshold of the bubble layer material and cannot form a bubble structure or adjust the bubble structure; if the laser power is too large, it will cause excessive damage to the bubble layer material, affecting the overall strength of the quartz crucible and making it unable to be used normally.

[0028] In a specific embodiment of the present invention, the focal length of the laser in the laser internal engraving is 100 - 110 mm, such as 100 mm, 101 mm, 102 mm, 103 mm, 104 mm, 105 mm, 106 mm, 107 mm, 108 mm, 109 mm, or 110 mm, etc., but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0029] In a specific embodiment of the present invention, controlling the focal length of the laser within 100 - 110 mm can ensure the size of the laser - focused spot on the bubble layer. During the focusing distance process, if the spot is too large, the size of the generated bubble structure will be too large, which will affect the strength of the quartz crucible and cannot meet the requirements of heat conduction at the same time; if the focusing length is too small, the spot is too small, which is not conducive to the efficient processing of the quartz crucible. At the same time, the laser energy is too concentrated, making it difficult to reasonably control the bubble structure.

[0030] In a specific embodiment of the present invention, the spot diameter of the laser in internal laser engraving is 0.01 - 0.2 mm, such as 0.01 mm, 0.012 mm, 0.015 mm, 0.018 mm, 0.02 mm, 0.022 mm, 0.025 mm, 0.028 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm or 0.2 mm, etc., but not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0031] In a specific embodiment of the present invention, the laser used in internal laser engraving is pulsed laser. The pulse width of the pulsed laser can be adjusted according to the laser power and processing conditions, and no further limitation is made here.

[0032] In a specific embodiment of the present invention, the preparation method of the quartz crucible blank includes die forming, melting and forming, cooling, and demolding in sequence.

[0033] In a specific embodiment of the present invention, die forming includes substrate forming and functional layer forming in sequence.

[0034] In a specific embodiment of the present invention, the method of die forming can be adding base quartz sand into the mold for substrate forming; then adding bubble - layer quartz sand, intermediate composite - layer additive powder, and transparent quartz sand into the mold in sequence for functional layer forming.

[0035] In a specific embodiment of the present invention, the process parameters of die forming, specifically including the process parameters in the substrate - forming stage and the process parameters in the functional - layer - forming stage, are all conventional parameters in the field of quartz crucibles. They can be adjusted according to the production requirements of the quartz crucible and the type of materials, and no further limitation is made here.

[0036] In a specific embodiment of the present invention, the specific types of materials of the quartz crucible, such as base quartz sand, bubble - layer quartz sand, intermediate composite - layer additive powder, and transparent quartz sand, can be adjusted according to the production requirements and types of the quartz crucible, and no further limitation is made here.

[0037] In a specific embodiment of the present invention, the melting and forming can be carried out by arc melting. High-temperature arcs are released through graphite electrodes to melt the quartz sand. The parameters of arc melting, such as temperature, arc starting power, and electrode power, can be adjusted according to the melting conditions and the types of materials, and no further limitations are provided here.

[0038] In a specific embodiment of the present invention, the cooling method can be natural cooling, air cooling, water cooling, etc. The cooling rate can be adjusted according to the production requirements of the quartz crucible and the types of materials, and no further limitations are provided here.

[0039] In a specific embodiment of the present invention, sandblasting treatment means spraying quartz sand on the surface of the crucible blank with a spray gun to remove surface attachments.

[0040] In a specific embodiment of the present invention, any common demoulding treatment method can be used for demoulding, such as knocking on the outer surface of the mold to separate the quartz crucible blank from the mold.

[0041] In a specific embodiment of the present invention, after internal laser engraving, the quartz crucible blank is cleaned and coated with barium.

[0042] In a specific embodiment of the present invention, the cleaning can include pickling, water washing, and high-pressure and / or ultrasonic cleaning carried out in sequence to remove residual ions on the surface of the quartz crucible. Among them, pickling can use an HF aqueous solution with a concentration of 6-8%. The parameters of high-pressure cleaning and ultrasonic cleaning can be adjusted according to the cleaning effect, and no further limitations are provided here.

[0043] In a specific embodiment of the present invention, the method of barium coating can be to dissolve barium hydroxide powder in water, put it into a barium coating machine, and evenly spray it on the surface of the quartz crucible blank.

[0044] In a specific embodiment of the present invention, the process of the preparation method of the quartz crucible with a bubble-containing structure is as Figure 1 shown, and specifically includes the following steps:

[0045] Step 1: Weighing materials: Weigh the raw materials required for preparation according to the formula, select high-purity natural quartz sand, and polish it with a polishing machine. Add the required weight of quartz sand into the mold, and form the crucible blank through the mold;

[0046] Step 2: Mold forming: Add the required weight of quartz sand into the mold, and form the base through the mold; sequentially add the required weight of bubble layer quartz sand, intermediate composite layer additive powder, and transparent layer quartz sand into the mold, and form the functional layer through the mold;

[0047] Step 3: Melting: Transfer the mold into an arc melting furnace, and melt the quartz sand by releasing high-temperature arcs through graphite electrodes for melting;

[0048] Step 4 Cooling: Cool the mold to form a quartz crucible blank;

[0049] Step 5 Sandblasting: Spray quartz sand on the surface of the crucible blank with a spray gun to remove surface attachments;

[0050] Step 6 Demolding: Tap the outer surface of the mold to separate the crucible blank from the mold;

[0051] Step 7 Laser internal engraving: Perform laser internal engraving on the outer layer of the quartz crucible blank to prepare a bubble layer;

[0052] Step 8 Cleaning: First, perform pickling by immersing it in a 6 - 8% HF pickling tank for cleaning, then take it out and clean it in clean water, and then perform high - pressure cleaning and ultrasonic cleaning to remove surface residual ions;

[0053] Step 9 Barium coating: Dissolve barium hydroxide powder in water, put it into a barium - coating machine, and evenly spray it on the surface of the quartz crucible blank to obtain a quartz crucible.

[0054] To better illustrate the present invention and facilitate understanding of its technical solution, the typical but non - restrictive embodiments of the present invention are as follows:

[0055] Embodiment 1

[0056] This embodiment provides a method for preparing a quartz crucible with a bubble structure, and the preparation method includes:

[0057] Use a laser internal engraving machine to perform laser internal engraving on the outer layer of the quartz crucible blank after melting and forming to prepare a bubble layer;

[0058] In the laser internal engraving, the laser is a green laser with a wavelength of 510 - 550 nm, the power of the laser is 10 W, the focal length of the laser is 100 mm, and the spot diameter of the laser is 0.02 mm;

[0059] After laser internal engraving, use a 7% HF acid aqueous solution to pickle the quartz crucible blank, and then perform water washing, high - pressure cleaning and ultrasonic cleaning to remove surface residual ions;

[0060] Dissolve barium hydroxide powder in water, put it into a barium - coating machine, and evenly spray it on the surface of the quartz crucible blank to obtain a quartz crucible with a bubble structure.

[0061] Embodiment 2

[0062] Except that the power of the laser is 20 W, the other conditions of this embodiment are the same as those of Embodiment 1.

[0063] Embodiment 3

[0064] Except that the power of the laser is 30 W, the other conditions of this embodiment are the same as those of Embodiment 1.

[0065] Example 4

[0066] In this example, except that the focal length of the laser is 105 mm, the other conditions are the same as those in Example 1.

[0067] Example 5

[0068] In this example, except that the focal length of the laser is 110 mm, the other conditions are the same as those in Example 1.

[0069] Example 6

[0070] Except that the spot diameter of the laser is 0.01 mm, the other conditions are the same as those in Example 1.

[0071] Example 7

[0072] Except that the spot diameter of the laser is 0.03 mm, the other conditions are the same as those in Example 1.

[0073] Comparative Example 1

[0074] In this comparative example, except that no internal laser engraving is performed, the other conditions are the same as those in Example 1.

[0075] Comparative Example 2

[0076] In this comparative example, except that the power of the laser is 50 W, the other conditions are the same as those in Example 1.

[0077] Comparative Example 3

[0078] In this comparative example, except that the focal length of the laser is 50 mm, the other conditions are the same as those in Example 1.

[0079] Comparative Example 5

[0080] In this comparative example, except that the focal length of the laser is 150 mm, the other conditions are the same as those in Example 1.

[0081] Comparative Example 6

[0082] In this comparative example, except that the spot diameter of the laser is 0.05 mm, the other conditions are the same as those in Example 1.

[0083] In Examples 1-7 and Comparative Examples 1-6, the preparation method of the quartz crucible blank includes die forming, melting forming, cooling, sandblasting, and demolding carried out in sequence.

[0084] Die forming includes substrate forming and functional layer forming carried out in sequence. The method of die forming can be to add base quartz sand into the mold for substrate forming; then add bubble layer quartz sand, intermediate composite layer additive powder, and transparent quartz sand into the mold in sequence for functional layer forming.

[0085] The specific steps of melting and forming, including exhaust treatment, envelope treatment, transparent layer melting, bubble layer melting, and cooling, are as follows:

[0086] In the exhaust treatment, a mixed gas of helium (volume fraction 85%) and oxygen (volume fraction 15%) is introduced and vacuum is pumped. The density of the elemental gas is less than that of air;

[0087] In the envelope treatment, the graphite electrode arcs, and the mixed gas is kept flowing in and vacuum is pumped;

[0088] In the transparent layer melting, the mixed gas is kept flowing in and vacuum is pumped;

[0089] In the bubble layer melting, the introduction of the mixed gas and vacuum pumping are stopped;

[0090] After the bubble layer melting, the graphite arc is turned off, and the quartz crucible is rapidly cooled; after the cooling is completed, it is taken out of the furnace and the melting is finished.

[0091] The specific conditions of exhaust treatment, envelope treatment, transparent layer melting, bubble layer melting, and cooling are shown in Table 1.

[0092] Table 1

[0093] After cooling, quartz sand is sprayed on the surface of the crucible blank with a spray gun to remove surface attachments, and the outer surface of the mold is tapped to separate the crucible blank from the mold.

[0094] The base quartz sand is high-purity natural quartz sand with a purity of silicon dioxide above 99.99%. The bubble layer uses natural high-purity quartz sand NC4A, the transparent layer uses synthetic quartz sand, and the intermediate layer powder is natural high-purity quartz sand NC4A.

[0095] The number of bubbles per unit area, the average diameter of bubbles, and the bubble distribution uniformity of the bubble layers of the quartz crucibles with bubble structures prepared in Examples 1-7 and Comparative Examples 1-6 were tested, and the results are shown in Table 2.

[0096] The testing of the number of bubbles per unit area, the average diameter of bubbles, and the bubble distribution uniformity is carried out by combining an optical microscope and image processing. The specific steps are as follows:

[0097] 1. Sample preparation: Slicing or surface polishing to ensure that the bubbles are exposed on the observation surface;

[0098] 2. Microscopic imaging: Using an optical microscope to take high-resolution images (the scale needs to be calibrated);

[0099] 3. Image processing:

[0100] (1)Perform threshold segmentation through software (such as ImageJ, MATLAB) to extract the bubble contour;

[0101] (2)Automatically count the number of bubbles, calculate the equivalent diameter of each bubble, and calculate the bubble distribution uniformity per unit area;

[0102] 4. Result output: Number of bubbles per unit area (pieces / mm²), average diameter (μm), bubble distribution uniformity per unit area (%), and distribution histogram.

[0103] Table 2

[0104] It can be seen from the test results in Table 2 that the preparation methods of the quartz crucibles with bubble structures provided in Examples 1-7 can improve the bubble distribution uniformity in the bubble layer of the quartz crucibles. From the test results of Examples 1-3, it can be seen that increasing the laser power can reduce the number of bubbles per unit area and increase the average diameter of the bubbles. From the test results of Examples 1 and 4-5, it can be seen that when increasing the laser focal length, the number of bubbles per unit area first increases and then decreases, and the average diameter of the bubbles gradually increases. From the test results of Examples 1 and 6-7, it can be seen that when the spot diameter is small, the number of bubbles per unit area is small and the average diameter of the bubbles is large. Increasing the spot diameter increases the number of bubbles per unit area and decreases the average diameter of the bubbles, but continuously increasing the spot diameter makes the number of bubbles per unit area and the average diameter of the bubbles almost remain unchanged. Comparative Example 1 did not use laser engraving, and the laser parameters in Comparative Examples 1-6 were all outside the optimal parameter range, resulting in a significant decrease in the bubble distribution uniformity compared with Example 1.

[0105] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the detailed structural features of the present invention, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, and the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0106] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0107] In addition, it should be noted that in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0108] In addition, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should equally be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a quartz crucible with a bubble-containing structure, characterized in that, The preparation method includes laser internal engraving on the outer layer of the quartz crucible blank after melting and forming to prepare a bubble structure.

2. The preparation method according to claim 1, characterized in that, The laser in the laser internal engraving includes any one or a combination of at least two wavelengths of lasers such as green laser with a wavelength of 510 - 550 nm, infrared laser with a wavelength of 1000 - 1050 nm, or ultraviolet laser with a wavelength of 340 - 360 nm, etc.

3. The preparation method according to claim 1, wherein The power of the laser in the laser internal engraving is 1 - 30 W.

4. The preparation method according to claim 1, characterized in that, The focal length of the laser in the laser internal engraving is 100 - 110 mm.

5. The preparation method according to claim 1, characterized in that, The spot diameter of the laser in the laser internal engraving is 0.01 - 0.2 mm.

6. The preparation method according to claim 1, characterized in that, The preparation method of the quartz crucible blank includes die forming, melting and forming, cooling, and demolding in sequence.

7. The preparation method according to claim 6, wherein The die forming includes substrate forming and functional layer forming in sequence.

8. The preparation method according to claim 6, characterized in that, Sandblasting treatment is carried out before demolding.

9. The preparation method according to claim 1, wherein, After the laser internal engraving, the quartz crucible blank is cleaned and coated with barium.

10. A quartz crucible with a bubble-containing structure, characterized in that, The quartz crucible with a bubble structure is prepared by the preparation method of the quartz crucible with a bubble structure according to any one of claims 1 - 9.

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