Process for producing single large-size circular single crystal at low cost
By preparing a coating in a circular crucible, using large-sized single-crystal seed crystals, and controlling the temperature gradient, the problem of producing large-diameter circular single crystals has been solved, enabling low-cost and high-efficiency production of large-sized single-crystal silicon materials.
Patent Information
- Application Number
- CN202511146301.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-15
- Publication Date
- 2025-11-21
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing technologies make it difficult to produce large-diameter circular single crystals at low cost, and the Czochralski method is difficult to stably mass-produce large-size single-crystal silicon materials.
Specific process steps and parameter control are employed, including preparing a coating on the inner surface of a circular crucible, using a single large-sized circular single crystal as a seed crystal, and controlling the longitudinal and transverse temperature gradients to make the growth interface grow in a mushroom-shaped convex form. Combined with optimization of crucible size and charge weight, ceramic quartz rings are used to avoid adhesion.
While ensuring the quality of single crystals, production costs were reduced, raw material utilization and production efficiency were improved, energy consumption was reduced, and stable growth and efficient production of large-size single crystals were achieved.
Smart Images
Figure CN120989714A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor processing technology, and in particular to a low-cost process for producing single large-size circular single crystals. Background Technology
[0002] The global semiconductor silicon component supply chain is highly globalized, with etching silicon components being consumable parts that occupy the majority of the market share. As process nodes continue to advance, the number of etching steps in integrated circuit manufacturing increases significantly, further boosting the demand for etching silicon components.
[0003] Currently, semiconductor-grade silicon components are mainly fabricated using the Czochralski (CZ) process, which is the most commonly used method for single crystal growth. With the trend towards larger silicon wafers, higher demands are being placed on the size of single-crystal silicon materials used for etching, requiring the fabrication of single-crystal silicon components larger than the wafer itself. However, achieving stable mass production of large-size single-crystal silicon using the Czochralski method presents significant technological barriers.
[0004] The development of semiconductor silicon components is closely related to the evolution of semiconductor equipment technology and process nodes. Silicon components made of high-purity single-crystal silicon have less impact on etching processes, and are therefore more widely used in etching equipment for advanced processes such as 7nm and 5nm. However, in scenarios with lower process requirements (above 7nm), to reduce costs, lower-cost cast polycrystalline silicon components (mainly including silicon exhaust rings, silicon rings, etc.) are often used, because the cost of Czochralski-grown single-crystal silicon is much higher than that of cast polycrystalline silicon for the same size. Furthermore, the maximum size currently achievable using the Czochralski method is around 22 inches, making it difficult to produce large-diameter circular single crystals. Therefore, this application provides a low-cost process for producing single large-size circular single crystals to meet this demand. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a low-cost process for producing a single large-size circular single crystal to solve the problem of existing difficulties in producing large-diameter circular single crystals.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:
[0007] A low-cost process for producing single large-size circular monocrystalline crystals includes the following steps:
[0008] Step 1: Select a round crucible, prepare a coating on the inner surface of the round crucible, and dry it for later use;
[0009] Step 2: Place a circular seed crystal in the center of the circular crucible;
[0010] Step 3: Place a ceramic quartz ring between the inner wall of the circular crucible and the circular seed crystal, and then load the material.
[0011] Step 4: After the material is loaded, install a protective plate and a cover plate on the outside of the circular crucible, and then put it into a circular hot zone casting furnace for crystal growth.
[0012] Step 5, crystal growth stage: control the longitudinal and transverse temperature gradients to make the interface grow in a mushroom-shaped convex form;
[0013] Step six: After crystal growth is completed, annealing is performed, followed by cooling. The crystals are removed from the furnace when the temperature is below 400°C.
[0014] Optionally, in step one, the inner diameter of the circular crucible is 590 mm.
[0015] Optionally, in step one, a coating layer is prepared at a height of 600 mm or below on the inner surface of the circular crucible. The coating layer is prepared by spraying, brushing, or dipping.
[0016] Optionally, in step one, the inner diameter of the circular crucible is greater than 600 mm.
[0017] Optionally, in step two, the thickness of the circular seed crystal ranges from 10 to 25 mm, and the diameter of the circular seed crystal ranges from 300 to 500 mm.
[0018] Optionally, in step two, the thickness of the circular seed crystal ranges from 10 to 25 mm, and the diameter of the circular seed crystal is greater than 500 mm.
[0019] Optionally, in step three, the inner diameter of the ceramic quartz ring is 0.5 to 1 mm larger than that of the circular seed crystal, so as to facilitate the placement of the circular seed crystal into the ceramic quartz ring; the outer diameter of the ceramic quartz ring is 1 to 10 mm smaller than that of the inner diameter of the circular crucible, so as to facilitate the placement of the ceramic quartz ring into the circular crucible; and the height of the ceramic quartz ring is 3 to 10 mm smaller than that of the circular seed crystal.
[0020] Optionally, in step three, a coating is brushed onto the upper surface of the ceramic quartz ring to prevent it from sticking to the silicon ingot and to facilitate demolding.
[0021] Optionally, in step three, the weight range of the loaded material is 200–260 kg.
[0022] Optionally, in step three, the weight of the loaded material is greater than 260 kg.
[0023] Compared with the prior art, the present invention has at least the following beneficial effects:
[0024] In the above scheme, by adopting specific process steps and parameter control, production costs are effectively reduced while ensuring single crystal quality. By optimizing parameters such as crucible size and charge weight, the utilization rate of raw materials is improved, and waste in the production process is reduced. At the same time, the rational process design reduces energy consumption, making the entire production process more economical and efficient.
[0025] By precisely controlling the crucible size, seed crystal size, and the size and position of the ceramic quartz ring, a stable and suitable spatial environment is provided for single crystal growth. Furthermore, a single large-sized circular single crystal is used as the seed crystal, and the ingot furnace hot zone and crucible are circular in structure. This design allows crystals to grow smoothly to a large size, and the large-sized single crystal produced from the ingot can be cut into single crystal seeds, achieving self-sufficiency in seed crystals. This further reduces production costs, forming a sustainable production cycle and providing strong support for the large-scale production of large-sized single crystals.
[0026] In the above scheme, during crystal growth, the longitudinal and transverse temperature gradients are strictly controlled to ensure that the growth interface exhibits a mushroom-shaped convex growth pattern. This growth method helps reduce defects and dislocations during crystal growth and ensures the crystal orientation consistency. Simultaneously, using a single large-sized circular single crystal as a seed crystal avoids the grain boundary problems associated with polycrystalline seed crystals, resulting in a single crystal without grain boundaries and improving its quality and performance.
[0027] Applying a coating to the upper surface of the ceramic quartz ring and preparing a coating on the inner surface of the crucible effectively prevents adhesion between the ceramic quartz ring and the silicon ingot, and between the crucible and the silicon ingot, greatly facilitating the demolding operation. This not only improves production efficiency but also reduces damage to the single crystal during demolding, ensuring the integrity of the single crystal. Attached Figure Description
[0028] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the invention and, together with the specification, further serve to explain the principles of the invention and enable those skilled in the art to practice and use the invention.
[0029] Figure 1 A process flow diagram for low-cost production of a single large-size circular monocrystalline crystal;
[0030] Figure 2 This is a process flow diagram of Embodiment 1 of this application;
[0031] Figure 3 This is a process flow diagram of Embodiment 2 of this application;
[0032] Figure 4 This is a schematic diagram of the structure of this application;
[0033] Figure 5 This is a schematic diagram of the crystal growth process in this application.
[0034] Figure label:
[0035] 1. Furnace body; 2. Exhaust pipe; 3. Upper heat insulation cage; 4. Graphite cover plate; 5. Ceramic quartz circular crucible; 6. Protective plate; 7. Heater; 8. Crucible bottom plate; 9. DSS graphite block; 10. Graphite support rod and tray; 11. Lower heat insulation cage; 12. Ceramic quartz ring; 13. Single crystal circular seed crystal; 14. Cast single crystal silicon ingot.
[0036] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to this specific structure, device and environment. Those skilled in the art can adjust or modify these devices and environments according to specific needs. Detailed Implementation
[0037] The present invention provides a low-cost process for producing single large-size circular monocrystalline crystals, described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments; those skilled in the art can also use other alternative methods to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.
[0038] It should be noted that the use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.
[0039] Generally, terms can be understood at least partly from their use in context. For example, depending at least partly on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, depending at least partly on the context, to allow for the presence of other factors that are not necessarily explicitly described.
[0040] It is understood that the meanings of “on”, “above”, and “above” in this invention should be interpreted in the broadest manner, such that “on” means not only “directly on” something, but also includes the meaning of being “on” something with an intervening feature or layer, and that “above” or “above” means not only “on” something, but also includes the meaning of being “on” something without an intervening feature or layer.
[0041] Furthermore, spatially related terms such as “below,” “under,” “lower,” “above,” and “upper” are used herein for convenience to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the accompanying drawings. Spatially related terms are intended to cover different orientations in the use or operation of the device other than those depicted in the accompanying drawings. The device may be oriented in other ways, and the spatially related descriptive terms used herein can be interpreted similarly.
[0042] like Figures 1 to 3 As shown, embodiments of the present invention provide a low-cost process for producing a single large-size circular monocrystalline crystal.
[0043] Example 1
[0044] Step 1, Crucible Preparation: Select a circular crucible with an inner diameter of 590mm. This inner diameter is carefully designed to ensure sufficient space for single crystal growth while effectively controlling costs. Apply a coating to the inner surface of the circular crucible at a height of 600mm and below using a spraying method. During spraying, control the spray pressure, angle, and movement speed of the spray gun to ensure the coating evenly covers the designated area on the inner surface of the crucible. After spraying, place the crucible in a drying device and dry it at 120℃ for 2 hours to remove moisture from the coating and enhance the adhesion between the coating and the inner surface of the crucible. Set aside for use after drying.
[0045] Step 2, Seed Crystal Laying: Select a round seed crystal with a thickness of 15mm and a diameter of 400mm. Before laying, clean the surface of the round seed crystal by wiping it with a lint-free cloth dampened with a suitable amount of alcohol to remove dust, oil, and other impurities, ensuring the surface is clean and flat. Then, carefully lay the round seed crystal in the center of the round crucible, ensuring it is tightly fitted to the bottom of the crucible without air bubbles or gaps.
[0046] Step 3: Placing the Ceramic Quartz Ring and Loading the Crucible: A ceramic quartz ring is selected, with an inner diameter 0.8 mm larger than the circular seed crystal. This size design facilitates the smooth placement of the circular seed crystal into the ceramic quartz ring while ensuring a suitable gap between them to prevent damage from mutual compression due to thermal expansion during subsequent processes. The outer diameter of the ceramic quartz ring is 5 mm smaller than the inner diameter of the circular crucible, facilitating accurate placement of the ceramic quartz ring into the circular crucible. The height of the ceramic quartz ring is 6 mm smaller than the circular seed crystal. Before placing the ceramic quartz ring, a coating is brushed onto its upper surface. The coating should be applied evenly and with consistent thickness to avoid coating accumulation or missed areas. This coating prevents the ceramic quartz ring from adhering to the subsequently grown silicon ingot, facilitating demolding.
[0047] After placing the ceramic quartz ring, the silicon was loaded, with a total weight of 230 kg. During loading, the silicon was poured slowly and evenly into the circular crucible to avoid excessive accumulation or voids, ensuring uniform silicon distribution and providing favorable conditions for subsequent crystal growth.
[0048] Step 4: Install the protective plate and cover plate and place the crucible in the furnace: After the material is loaded, install the protective plate and cover plate on the outside of the circular crucible. The protective plate and cover plate are made of high-temperature resistant and high-strength materials, and their dimensions are matched to the circular crucible. During installation, ensure that the protective plate and cover plate fit tightly against the circular crucible without any looseness, so as to protect the circular crucible from the influence of the external environment during crystal growth and maintain the stability of the thermal field. Then, place the circular crucible with the protective plate and cover plate installed into the circular thermal field ingot casting furnace for crystal growth.
[0049] Step five, crystal growth: During the crystal growth stage, the longitudinal and transverse temperature gradients are precisely controlled. By adjusting parameters such as the power of the heating elements and the flow rate of the cooling system within the ingot furnace, the longitudinal temperature gradient is maintained within a suitable range, prompting the crystal to grow upwards from the seed crystal surface. Simultaneously, the transverse temperature gradient is controlled, resulting in a mushroom-shaped convex growth interface. This mushroom-shaped convex growth interface helps reduce defects during crystal growth and improves crystal quality. Throughout the crystal growth process, parameters such as temperature and pressure are monitored in real time, and control parameters are adjusted promptly based on the monitoring results to ensure the stability and consistency of crystal growth.
[0050] Step Six, Annealing and Cooling: After crystal growth, annealing is performed. The temperature inside the ingot furnace is slowly raised to the annealing temperature and held for a certain period of time to allow the internal stress of the crystal to be fully released, reducing defects and dislocations in the crystal. The annealing temperature and time are optimized and determined according to the crystal material and size. In this case, the annealing temperature is 1100℃ and the annealing time is 8 hours.
[0051] After annealing, a cooling process is performed. A segmented cooling method is used: first, cooling is carried out at a slower rate to 600°C, at a cooling rate of 50°C per hour; then, cooling is carried out at a slightly faster rate to below 400°C, at a cooling rate of 100°C per hour. After cooling to below 400°C, the ingot furnace is opened, and the grown single crystal is removed from the furnace.
[0052] Example 2
[0053] Step 1, Crucible Preparation: Select a circular crucible with an inner diameter of 620mm (greater than 600mm). This larger size provides space for growing larger single crystals. Prepare a coating on the inner surface of the circular crucible using a brush. Use a special brush and brush in a specific direction and sequence to ensure the coating evenly covers the entire inner surface. After brushing, place the crucible in a well-ventilated environment to air dry for 24 hours, allowing the solvent in the coating to fully evaporate and achieving a good drying effect. The crucible is then ready for use.
[0054] Step 2, Seed Crystal Laying: Select a round seed crystal with a thickness of 20mm and a diameter of 550mm (greater than 500mm). Pre-treat the round seed crystal by placing it in an ultrasonic cleaner, adding an appropriate amount of cleaning agent, and ultrasonically cleaning for 15 minutes to thoroughly remove any tiny impurities and contaminants from the seed crystal surface. After cleaning, rinse thoroughly with deionized water and dry with nitrogen gas. Then carefully lay the round seed crystal in the center of a round crucible, ensuring it is stable and centered.
[0055] Step 3: Placing the ceramic quartz ring and loading the crucible: The selected ceramic quartz ring has an inner diameter 1mm larger than the circular seed crystal, an outer diameter 8mm smaller than the inner diameter of the circular crucible, and a height 8mm smaller than the circular seed crystal. A coating is prepared on the surface of the ceramic quartz ring using a dip-coating method. The ceramic quartz ring is immersed in the coating solution for a certain period of time, then slowly removed, allowing a uniform coating layer to adhere to its surface. After dip-coating, the ceramic quartz ring is placed in a ventilated area to dry.
[0056] During loading, the weight of the silicon material is 280 kg (greater than 260 kg). The silicon material is poured into the circular crucible in multiple batches, with gentle shaking after each pour to allow the silicon to settle naturally and fill the crucible tightly, avoiding voids and gaps. During the loading process, carefully observe the distribution of the silicon material and adjust the loading position as needed to ensure even distribution within the crucible.
[0057] Step 4, Install the protective plate and cover plate and place it in the furnace: After the material is loaded, install the protective plate and cover plate in the same way as in Example 1. Ensure that the protective plate and cover plate are firmly installed and well sealed to prevent external interference to the thermal field during crystal growth. Then, place the circular crucible into the circular thermal field ingot casting furnace, ready for crystal growth.
[0058] Step 5, Crystal Growth: During the crystal growth stage, an advanced temperature control system precisely controls the longitudinal and transverse temperature gradients. Optimal temperature gradient parameters are determined using a combination of computer simulation and experimental optimization to ensure the growth interface maintains a mushroom-shaped convex growth pattern. Throughout the crystal growth process, data such as temperature, pressure, and crystal growth rate are collected in real time, and the control strategy is adjusted promptly through data analysis to ensure a stable and reliable crystal growth process and produce high-quality crystals.
[0059] Step Six, Annealing and Cooling: After crystal growth, annealing is performed. The ingot furnace temperature is raised to 1150℃ for annealing for 10 hours to fully release and uniformly distribute the internal stress of the crystal. After annealing, segmented cooling is used. First, it is cooled to 700℃ at a rate of 40℃ per hour, and then cooled to below 400℃ at a rate of 80℃ per hour. After cooling to below 400℃, the single crystal is removed from the furnace.
[0060] like Figure 4 and Figure 5 As shown, the present invention provides a low-cost process for producing single large-size circular monocrystalline silicon crystals. Applied to the above embodiment, a lower heat insulation cage 11 is provided at the bottom of the furnace body 1, and an upper heat insulation cage 3 is provided at the top of the lower heat insulation cage 11. DSS graphite blocks 9 are placed at the bottom of both the lower and upper heat insulation cages 11 and 3. A crucible bottom plate 8 is provided on top of the DSS graphite blocks 9. A protective plate 6 is provided around the crucible bottom plate 8. A ceramic quartz circular crucible 5 is placed inside the protective plate 6. A graphite cover plate 4 is provided on top of the protective plate 6. A heater 7 is provided around the perimeter of the protective plate 6. A single-crystal circular seed crystal 13 is placed at the center of the bottom of the ceramic quartz circular crucible 5. A cast single-crystal silicon ingot 14 is placed on top of the single-crystal circular seed crystal 13. A ceramic quartz ring 12 is placed between the single-crystal circular seed crystal 13 and the inner wall of the ceramic quartz circular crucible 5. A graphite support rod and a tray 10 are provided at the bottom of the DSS graphite blocks 9. An exhaust pipe 2 is provided on top of the graphite cover plate 4, extending outside the furnace body 1.
[0061] The technical solution provided by this invention:
[0062] By employing specific process steps and parameter control, production costs were effectively reduced while ensuring single crystal quality. Optimizing parameters such as crucible size and charge weight improved raw material utilization and reduced waste during production. Simultaneously, the rational process design reduced energy consumption, making the entire production process more economical and efficient.
[0063] The process of this invention enables the successful production of large-sized circular single crystals. By precisely controlling the crucible size, seed crystal size, and the size and position of the ceramic quartz ring, a stable and suitable spatial environment is provided for single crystal growth, allowing the crystal to grow smoothly to a large size and meeting market demand for large-sized single crystals. During crystal growth, strict control of the longitudinal and transverse temperature gradients results in a mushroom-shaped convex growth interface. This growth method helps reduce defects and dislocations during crystal growth and ensures crystal orientation consistency. Simultaneously, using a single large-sized circular single crystal as the seed crystal avoids the grain boundary problems associated with polycrystalline seed crystals, resulting in a single crystal without grain boundaries, thus improving the quality and performance of the single crystal. Applying a coating to the upper surface of the ceramic quartz ring and preparing a coating on the inner surface of the crucible effectively prevents adhesion between the ceramic quartz ring and the silicon ingot, and between the crucible and the silicon ingot, greatly facilitating demolding. This not only improves production efficiency but also reduces damage to the single crystal during demolding, ensuring the integrity of the single crystal.
[0064] One of the key technical aspects of this invention is the use of a single large-size circular single crystal as a seed crystal, and the hot zone of the casting furnace and the crucible are circular structures. This design makes it possible to produce larger-size single crystals, and the large-size single crystal produced from the casting can be cut into single crystal seed crystals, achieving self-sufficiency in seed crystals, further reducing production costs, forming a sustainable production cycle, and providing strong support for the large-scale production of large-size single crystals.
[0065] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.
[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A low-cost process for producing single large-size circular monocrystalline crystals, characterized in that, Includes the following steps: Step 1: Select a round crucible, prepare a coating on the inner surface of the round crucible, and dry it for later use; Step 2: Place a circular seed crystal in the center of the circular crucible; Step 3: Place a ceramic quartz ring between the inner wall of the circular crucible and the circular seed crystal, and then load the material. Step 4: After the material is loaded, install a protective plate and a cover plate on the outside of the circular crucible, and then put it into a circular hot zone casting furnace for crystal growth. Step 5, crystal growth stage: control the longitudinal and transverse temperature gradients to make the interface grow in a mushroom-shaped convex form; Step six: After crystal growth is completed, annealing is performed, followed by cooling. The crystals are removed from the furnace when the temperature is below 400°C.
2. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step one, the inner diameter of the circular crucible is 590 mm.
3. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 2, characterized in that, In step one, a coating layer is prepared at a height of 600 mm or below on the inner surface of the circular crucible. The coating layer is prepared by spraying, brushing, or dipping.
4. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step one, the inner diameter of the circular crucible is greater than 600 mm.
5. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step two, the thickness of the circular seed crystal ranges from 10 to 25 mm, and the diameter of the circular seed crystal ranges from 300 to 500 mm.
6. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step two, the thickness of the circular seed crystal ranges from 10 to 25 mm, and the diameter of the circular seed crystal is greater than 500 mm.
7. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step three, the inner diameter of the ceramic quartz ring is 0.5-1 mm larger than that of the round seed crystal, which facilitates the placement of the round seed crystal into the ceramic quartz ring. The outer diameter of the ceramic quartz ring is 1-10 mm smaller than that of the inner diameter of the round crucible, which facilitates the placement of the ceramic quartz ring into the round crucible. The height of the ceramic quartz ring is 3-10 mm smaller than that of the round seed crystal.
8. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step three, a coating is brushed onto the upper surface of the ceramic quartz ring to prevent it from sticking to the silicon ingot and to facilitate demolding.
9. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step three, the weight range of the loading material is 200-260 kg.
10. The low-cost process for producing a single large-size circular monocrystalline crystal according to claim 1, characterized in that, In step three, the weight of the loading material is greater than 260 kg.