A crystal growth apparatus and a crystal growth method

Abstract

This invention provides a crystal growth apparatus and method, solving technical problems such as low wafer utilization, slow crystal growth speed, low efficiency, and poor uniformity in existing chip manufacturing processes. This invention abandons the traditional cylindrical ampoule structure and innovatively adopts a ring-shaped ampoule design, allowing the crystal to grow into a hollow cylindrical shape highly adapted to the target wafer specifications. The heater is placed inside the ampoule, replacing the traditional external heating method. During crystal growth, a central adjustment mechanism with insulating material concentrates heat on the crystal, reducing heat loss. The heater is surrounded by insulating material, effectively suppressing heat radiation leakage. Simultaneously, the structure supporting the ampoule is adjusted, making the entire device simple, low-cost, and lightweight.

Description

Technical Field

[0001] This invention belongs to the field of crystal growth technology, specifically relating to a high-efficiency and high-utilization crystal growth device and crystal growth method. Background Technology

[0002] In chip manufacturing, single crystal growth, wafer fabrication, and wafer dicing are the core processes. Single crystal growth involves loading high-purity raw materials into ampoules of a specific shape, placing them in a furnace, and heating them to melt and crystallize, growing a single crystal. Because ampoules are typically cylindrical, the grown single crystal is also cylindrical. Wafer fabrication involves cutting the cylindrical single crystal into wafers, which are then processed to form standardized wafers. Wafer dicing involves cutting wafers of the required specifications from the wafer according to the chip design requirements; the wafers are typically rectangular.

[0003] However, the above process has two significant drawbacks: ① Low wafer utilization. Since wafers are circular and chips are rectangular, unusable scraps are formed at the edges. Currently, to improve utilization, multiple wafers are often diced from the same wafer. This results in a crystal diameter much larger than the required wafer size, further increasing energy consumption and wasting wafers. ② Low crystal growth efficiency and poor uniformity. When cylindrical ampoules are heated in the furnace, a temperature difference forms between the center and edge due to the radial gradient of heat conduction, leading to uneven temperature distribution on the same horizontal plane. This temperature difference is mainly affected by the crystal diameter and the crystal's thermal conductivity. Reducing the crystal diameter can shorten the heat conduction path and improve radial temperature uniformity, but an excessively small diameter means that only one wafer can be diced from a single wafer, significantly reducing material utilization and production efficiency. Furthermore, the thermal conductivity of crystals, as an inherent physical property of the material, cannot be changed through artificial intervention. Therefore, traditional crystal growth methods generally suffer from a large temperature difference between the center and edge, a problem that is difficult to fundamentally solve. Typically, the temperature at the center of a crystal is higher than that at the edge, forming a concave isothermal surface. This severely affects the single crystal yield and growth efficiency. At the same time, the large temperature difference can also induce significant thermal stress and dislocation defects, reducing the crystal's performance yield. This contradiction makes it difficult to balance the pursuit of temperature uniformity and production efficiency, becoming a key bottleneck restricting the quality of crystal growth.

[0004] Therefore, it is necessary to explore a solution that can improve wafer utilization and crystal growth efficiency. Summary of the Invention

[0005] To address the shortcomings of existing chip manufacturing processes, such as low wafer utilization, slow crystal growth rate, low efficiency, and poor uniformity, this invention provides a high-efficiency and high-utilization crystal growth apparatus and crystal growth method.

[0006] To address the low wafer utilization rate in traditional processes, this invention conducts an in-depth analysis. The root cause lies in the lack of sufficient and reasonable integration and planning between crystal growth and the target wafer specifications, leading to significant wafer waste. To resolve this core issue, this invention proposes a geometrically reconstructed hollow cylindrical crystal growth scheme (referred to as a toroidal crystal), achieving a leap in wafer utilization through disruptive design. Specifically, this scheme abandons the traditional cylindrical ampoule structure and innovatively adopts a toroidal ampoule design (i.e., the ampoule's cross-section is circular), allowing the crystal to grow into a hollow cylindrical shape highly adapted to the target wafer specifications. This geometric optimization directly solves the dicing waste problem caused by the mismatch between wafer size and chip requirements in traditional processes. When dicing wafers on the toroidal wafer, material utilization can be increased to near the theoretical limit. Simultaneously, by integrating a heater inside the ampoule, heat is precisely applied to the crystal growth interface, significantly reducing energy loss caused by radial heat diffusion in traditional processes. More importantly, the crystal thickness reduction effect brought about by the ring structure fundamentally improves the uniformity of the thermal field. Due to the shortened heat conduction paths between the inner and outer walls, the temperature difference is controlled within an extremely low range, thereby significantly reducing thermal stress and dislocation defects, and improving the uniformity and single-crystal rate of crystal growth. It is worth emphasizing that this technological breakthrough is not a simple parameter adjustment, but involves a complete structural reconstruction of the growth apparatus, including multi-dimensional synergistic optimization of ampoule geometry, heater layout, and thermal field control strategies. Through precise matching of material selection and process parameters, the stability and industrial scalability of ring crystal growth are ultimately achieved. The core value of this invention lies in reverse-engineering the front-end requirements of chip manufacturing into crystal growth design. Through the deep integration of geometric theory and thermodynamic control, a paradigm shift from "process-driven" to "demand-driven" is achieved, providing a completely new technological path for high-utilization, high-efficiency, and low-defect crystal growth.

[0007] Based on the above inventive concept, and to achieve the above objectives, the technical solution provided by this invention is as follows:

[0008] A highly efficient and high-utilization crystal growth apparatus, characterized by comprising a growth furnace, a control center, a heater, and an ampoule.

[0009] The growth furnace is cylindrical in shape and features a modular design for easy installation and crystal growth operation. It comprises, from bottom to top, a heat-insulating base, a quartz cover, and a heat-insulating top cover, all coaxially mounted. The heat-insulating base is cylindrical with flat top and bottom surfaces, and is placed flat on a horizontal platform during installation to serve as a base for supporting other components. Above the heat-insulating base is a ring-shaped heat-insulating support platform with an outer diameter slightly smaller than the base, used to support ampoules and other structures used for crystal growth. The quartz cover is cylindrical and coaxially mounted on the heat-insulating base, located outside the heat-insulating support platform. The heat-insulating top cover is ring-shaped and has a central hole for easy insertion of the adjustment hub, allowing the adjustment hub to extend from the top cover.

[0010] The regulating hub is cylindrical and coaxially inserted into the growth furnace, forming an annular crystal growth cavity between itself and the quartz cover. Its top extends out of the heat-insulating top cover. The regulating hub of each crystal growth device includes two types: a regulating hub for heat preservation during the crystal growth stage and a regulating hub for heat conduction during the cooling stage.

[0011] The heater is stably supported inside the annular crystal growth cavity and is sleeved outside the adjustment center with a distance between them. It is a multi-segment heater, all of which adopt resistance heating. The working status of the heater is controlled by the heater controller.

[0012] The ampoule has a circular cross-section and serves as a container for growing ring-shaped crystals. Its top and bottom are stably mounted between the heater and the quartz cover via frosted quartz and an insulating support platform, respectively. The frosted quartz is also circular, and its bottom is provided with an annular groove that matches the top of the ampoule to limit and support the ampoule.

[0013] The quartz cover is divided into two parts from top to bottom. The upper part is a transparent section, which can be used to observe the situation inside the growth furnace. The lower part is a frosted section, which can block internal heat radiation to keep the entire device warm. The top of the frosted section is higher than the top of the ampoule to prevent heat from the ampoule from leaking out and to ensure a stable crystal growth environment.

[0014] Furthermore, the heater is a three-section heater, comprising a first heater, a second heater, and a third heater from top to bottom. All sections are made of spiral resistance wire. Specifically, the resistance wire is wound into a spiral shape, placed vertically, and stably supported within the annular crystal growth cavity by a ceramic rod. Based on the design requirements for the length of each heater section, wires are led out at corresponding positions to connect to the heater controller and power supply for operation. During the crystal growth stage, the regulating hub is made of refractory insulation material with a thermal conductivity ≤0.5W / (m·K), such as materials primarily composed of aluminum silicate, mullite, zirconium oxide, etc. During the cooling stage, the regulating hub is made of ceramic material with a thermal conductivity ≥2W / (m·K), such as corundum, silicon carbide, etc.

[0015] At high temperatures, heat transfer is mainly through thermal radiation. The ampoule is made of high-purity quartz that is completely transparent (such as GE214 high-purity quartz), which allows heat to be transferred to the crystal in a timely manner, enabling the crystal to respond quickly to temperature changes at the heater. The inner and outer diameters of the ampoule's annular cavity need to be determined based on the diameter and thickness of the target crystal, and its height can be determined based on the length of the target crystal.

[0016] Furthermore, the distance between the inner surface of the ampoule and the outer surface of the heater is denoted as L. ah Based on actual needs, its value range is 2S≤L ah ≤5S, where S is the pitch of the spiral resistance wire; when using spiral resistance wire for heating, local gaps within a single pitch in the height direction can lead to uneven temperature distribution near the surface of the resistance wire; when L ah Temperature field uniformity requirements can be met at ≥2S, but to miniaturize the control device, L needs to be further limited. ah ≤5S.

[0017] The upper and lower ends of the heater are each at least Dh longer than the top and bottom of the ampoule, respectively, and the heater satisfies Lh≥Lc+2Dh, where Lh is the total height of the heater, Lc is the height of the ampoule, and Dh is the inner diameter of the heater.

[0018] Furthermore, the geometric constraints between the ampoule size and the target wafer size are: (a / 2) 2 +(D1 / 2+b) 2 =(D2 / 2) 2 The formula is: dc = (D2 - D1) / 2; where D1 is the inner diameter of the ampoule annular cavity (equivalent to the inner diameter of the target crystal), D2 is the outer diameter of the ampoule annular cavity (equivalent to the outer diameter of the target crystal), dc is the thickness of the ampoule annular cavity (equivalent to the thickness of the target crystal), and a and b are the lengths of the short and long sides of the target wafer, respectively. To improve wafer utilization and reduce material waste, the present invention sets the direction of the long side b along the radial direction of the crystal. Based on the above formula, after determining the size of the target wafer, combined with the size of the heater and the distance between the inner surface of the ampoule and the outer surface of the heater, the reasonable inner and outer diameter values ​​of the ampoule annular cavity and the crystal can be calculated, and then the value of the ampoule annular cavity thickness dc can be determined.

[0019] Furthermore, taking into account both the heat preservation effect and the overall height of the device, the length of the top of the frosted section above the top of the ampoule is greater than or equal to D2 and less than or equal to 2D2.

[0020] Furthermore, the top of the regulating center extends at least 2Dh beyond the insulated top cover.

[0021] Furthermore, the spiral resistance wire is an iron-chromium-aluminum resistance wire; during the crystal growth stage, the material of the adjustment center is aluminum silicate insulation fiber; during the cooling stage, the material of the adjustment center is alumina ceramic; the insulation base, insulation support platform, and insulation top cover are all made of aluminum silicate insulation material.

[0022] Furthermore, the diameter of the spiral resistance wire is at least 10 mm.

[0023] Furthermore, this invention also provides a method for crystal growth using the aforementioned high-efficiency and high-utilization crystal growth apparatus, characterized by the following steps: S1. Installing the insulation base, insulation support platform, and heater into place; S2. Coaxially supporting the ampoule containing the crystal raw material on the insulation base via the insulation support platform; S3. Placing the frosted quartz on top of the ampoule and covering it with a quartz cover; S4. Installing the insulation top cover into place; S5. During the crystal growth stage, coaxially inserting the adjustment hub made of refractory insulation material into the growth furnace, adjusting the heater temperature according to the crystal growth method, and performing crystal growth; the crystal growth method is bottom-up crystal growth or outside-in crystal growth; S6. In the cooling stage after crystal growth, replacing the adjustment hub made of refractory insulation material with an adjustment hub made of thermally conductive material for cooling, ultimately obtaining the crystal.

[0024] Furthermore, in S5, for the outward-to-inward crystal growth method, the adjustment of the heater's maximum temperature is based on: Th - Tm = q·dc / k, where Tm is the crystal melting point, which is also the lowest temperature of the crystal's outer surface; Th is the heater's maximum temperature (i.e., the temperature of the crystal's inner surface); dc is the thickness of the ampoule annular cavity; k is the crystal's thermal conductivity; and q is the heat flux density. According to the aforementioned formula dc = (D2 - D1) / 2, the ampoule annular cavity thickness dc is calculated, which is the maximum crystal thickness required to meet the crystal growth requirements. Then, this value is substituted into Th - Tm = q·dc / k to calculate Th, which is the basis for adjusting the heater's maximum temperature. When the heater's maximum temperature meets the Th requirement, a crystal with a thickness of dc can be grown.

[0025] Compared with traditional methods, the technical difficulties of this invention lie in the following three aspects.

[0026] I. Optimization Design of Growth Device Structure

[0027] This invention designs the ampoule as a ring (i.e., the cross-section of the ampoule is circular), and changes the traditional heating method by placing the heater inside the ampoule. At the same time, it adjusts the structure supporting the ampoule, making the entire growth device simple, low-cost, and lightweight.

[0028] II. Selection of Materials for Each Component of the Growth Device

[0029] 1. Selection of heater material

[0030] The heater mainly provides heat for the crystal growth process. During the growth of compound semiconductor crystals, the crystal growth temperature usually exceeds 1000°C, and the crystal growth process lasts for a long time, usually on a monthly basis. Therefore, the stability requirements of the heater are high, and this invention puts forward high requirements for the heater material.

[0031] Because this invention requires frequent temperature increases and decreases and easy observation, a vacuum environment cannot be provided for the heater. Common graphite heating methods are unsuitable as they are prone to oxidation. Therefore, the main heating methods to consider are resistance heating and induction heating. However, induction heating requires an induction coil and a self-heating element, resulting in a complex structure unsuitable for the growth apparatus structure of this invention. Therefore, this invention chooses resistance heating, specifically using a spiral silicon molybdenum rod or a spiral resistance wire. Considering the brittleness of the silicon molybdenum rod and its susceptibility to breakage from minor impacts, this invention prioritizes spiral resistance wires (preferably with a diameter of 10 mm or more to improve stability), with iron-chromium-aluminum resistance wires, which offer good thermal stability and long service life, being the preferred choice.

[0032] 2. Selection of thermal insulation materials

[0033] The crystal growth process of this invention requires the coordinated cooperation of all components to achieve the expected results. Based on the functional implementation process, the selection of materials from the inside out must fully consider both safety and functionality.

[0034] The regulating core must provide good insulation during crystal growth to prevent excessive heat dissipation from the heater into the environment, thus avoiding energy waste. Simultaneously, the component material must be heat-resistant, chemically stable, and not decompose or produce toxic or harmful gases when heated, nor cause ampoule crystallization. Furthermore, the material must possess sufficient structural strength to prevent large deformation after softening. Based on these requirements, during the crystal growth stage, the regulating core is made of a refractory insulation material primarily composed of aluminosilicate, but mullite bricks, zirconia bricks, etc., can also be used. During the cooling stage, the regulating core needs to provide good thermal conductivity to accelerate overall cooling. Materials with high thermal conductivity, such as high-density alumina ceramics and SiC ceramics, can be selected, but graphite should not be used because it oxidizes rapidly at high temperatures.

[0035] The insulation base, insulation support platform, and insulation top cover need to withstand a certain amount of external force, so soft insulation materials should not be used. Materials with higher hardness and better insulation performance, such as aluminum silicate insulation bricks, should be selected.

[0036] As a container for crystal growth, the ampoule needs to have good stability. During high-temperature crystal growth, thermal radiation is dominant; therefore, the ampoule must be completely transparent to avoid blocking thermal radiation and causing uneven temperature distribution around the crystal. High-transparency and high-purity quartz such as GE214 can be used. To maintain the stability of the ampoule's thermal environment, a structure is needed at the top to block heat loss, while also being as clean and stable as possible. Therefore, frosted quartz is chosen. The rough, opaque white surface of frosted quartz provides good protection against thermal radiation. Similarly, the frosted section of the quartz cover is designed for the same purpose.

[0037] III. Selection of Parameters for Each Component of the Growth Unit

[0038] In order to achieve better results, the parameters of each component of the growth device need to be designed according to the present invention.

[0039] 1. Determining the distance between the outer surface of the heater and the inner surface of the ampoule

[0040] As described above, the heater uses a spiral resistance wire. Due to the pitch of the resistance wire, the temperature field at the gap between the spirals will vary slightly. Furthermore, since thermal radiation dominates in high-temperature environments, the radiant heat on the surface of the resistance wire will overlap, leading to uneven local temperature fields near the surface of the resistance wire. Let the pitch of the spiral resistance wire be S. The distance between the inner surface of the ampoule and the outer surface of the heater needs to be ≥2S to obtain a relatively uniform temperature field. However, if the distance between the heater and the ampoule is too far, the large gap will cause turbulent air convection, increased heat dissipation, and wasted energy. Furthermore, considering the need to reduce the size of the device, this distance should not exceed 5S.

[0041] 2. Determining the total height of the heater

[0042] Let the total height of the heater be denoted as Lh, the inner diameter of the heater as Dh, and the height of the ampoule as Lc. For bottom-up crystal growth, the bottom temperature of the crystal needs to be heated to the growth point Tm (i.e., the crystal melting point). However, there is a natural temperature drop near the bottom of the furnace and the top of the furnace. If the lower end of the heater is flush with the bottom of the crystal, a large temperature gradient will appear below, resulting in a highly unstable thermal field. Therefore, to ensure that the temperature below is not lower than the growth point Tm and to balance the stability of the thermal field below and above, the upper and lower ends of the heater must be at least Dh longer than the top and bottom of the ampoule, respectively, i.e., Lh ≥ Lc + 2Dh. For outside-in crystal growth, since the entire crystal needs to crystallize simultaneously along the thickness direction, a high degree of uniformity in the overall temperature field is required. To obtain a constant temperature at least along the length of the crystal, Lh ≥ Lc + 2Dh is also required.

[0043] 3. Geometric constraints between ampoule size and target wafer size

[0044] The inner and outer diameters of the ampoule's annular cavity are denoted as D1 and D2, respectively, and the thickness of the ampoule's annular cavity is denoted as dc. The two operating conditions are explained in detail here.

[0045] The first method: bottom-up crystal growth

[0046] For this crystal growth method, the temperature needs to be controlled to achieve a slow cooling process from bottom to top, with the crystal growth interface perpendicular to the height of the heater. Since there is inevitably a temperature difference between the inside and outside of the crystal, and this difference increases with the thickness of the crystal, the temperature difference must be minimized to obtain high-quality, large-size single crystals. Therefore, while meeting the final target wafer size requirements, the crystal thickness should be reduced as much as possible. The wafers required for the device are typically rectangular with a certain thickness (denoted as a and b for the short and long sides of the wafer, respectively). The inner diameter D1 of the ampoule's annular cavity (i.e., the crystal's inner diameter) can be determined based on the heater diameter and the number of target wafers that can be cut from a single annular wafer. Because this crystal growth method produces a hollow cylindrical crystal, there is no significant temperature difference between the center and surface of a cylindrical crystal. Therefore, theoretically, the crystal's inner diameter and height can be infinitely large, and can be adjusted according to actual conditions. However, the crystal's cross-section is annular. Therefore, when cutting rectangular cross-section wafers, the influence of the arc must be considered. The crystal thickness cannot be exactly equal to the length b of the long side of the wafer; otherwise, the target wafer cannot be cut. Calculations show that D1, D2, a, and b conform to a certain mathematical relationship, as detailed in [the following text is missing]. Figure 4 ,from Figure 4 As can be seen, the geometric constraints between the ampoule size and the target wafer size are as follows: (a / 2) 2 +(D1 / 2+b) 2 =(D2 / 2) 2 The thickness of the ampoule's annular cavity, dc, is calculated as (D2 - D1) / 2. From this relationship, given D1, the specific value of D2 that satisfies the required number of wafers can be obtained. Using this dimension for crystal growth, wafers of the target size can be obtained, where the crystal thickness is minimal and the crystal growth conditions are ideal.

[0047] The second method: crystal growth from the outside in.

[0048] For this crystal growth method, if the entire inner surface of the crystal can maintain a constant temperature, a relatively thick crystal can theoretically be achieved. According to the heat transfer law, the physical quantities of the crystal's outer surface minimum temperature Tm (i.e., the crystal's melting point), the crystal's inner surface temperature Th (i.e., the heater's maximum temperature), the crystal thickness dc (i.e., the thickness of the ampoule's annular cavity), the crystal's thermal conductivity k, and the heat flux density q must conform to the formula: Th - Tm = q·dc / k. Therefore, after solving for dc using the first method (this value is the crystal thickness that meets the wafer's requirements), the value of Th can be further derived from this formula and used as a reference for the heater's set temperature.

[0049] 4. Determining the position of the transparent section of the quartz dome

[0050] This invention addresses both the background technical problems and the inconvenience of observing the furnace interior during crystal growth. In traditional processes, heaters are located outside the crystal. If there are windows, the heat radiation from the heaters can directly escape, posing a safety hazard and causing significant temperature fluctuations. In this invention, the heaters are located inside the crystal, preventing direct heat radiation. Therefore, a ring of transparent quartz (the transparent section of the quartz cover) can be added near the furnace top as an observation window. When designing the position of the transparent section of the quartz cover, only the temperature stability of the crystal growth needs to be considered. Unlike the frosted section, the transparent section of the quartz cover allows heat radiation to penetrate, resulting in some heat loss. Therefore, the top of the frosted section of the quartz cover needs to be higher than the top of the ampoule to block heat radiation from the ampoule and prevent heat loss. The length by which the top of the frosted section of the quartz cover is higher than the top of the ampoule needs to be ≥D2, meaning at least one crystal diameter. Only then will heat dissipation from the transparent section of the quartz cover not affect the temperature field at the crystal location.

[0051] 5. Determining the height of the regulating center

[0052] The regulating center plays a crucial role in the entire crystal growth process. During the cooling stage, the material needs to be changed; therefore, the height of the regulating center needs to be at least 2Dh higher than the growth furnace, which is at least twice the inner diameter of the heater. This ensures a lower top temperature for safer handling. If a thermally conductive material is used during the cooling stage, a water-cooling device can be added to the top of the regulating center to achieve better heat dissipation and accelerate cooling.

[0053] 6. Setting the temperature values ​​for each section of the heater

[0054] In bottom-up crystal growth, crystal growth proceeds from the bottom up. The bottom of the crystal needs to be cooled and solidified first, and then the heater temperature is controlled to slowly push the solid-liquid interface upwards. Therefore, when setting the temperature field, the bottom temperature of the crystal will be lower than that of the middle and top. The heat in the melt has a significant impact on the solid-liquid interface. When the melt is at a high temperature, heat will be conducted to the lower, lower-temperature areas, causing heat accumulation in the center of the solid-liquid interface, which can easily form a concave interface. To reduce the impact of the melt heat on the lower solid-liquid interface, the top temperature needs to be set lower than that of the middle. This allows some of the heat in the melt to be transferred to the top, thus reducing the impact on the solid-liquid interface. Based on this approach, in this crystal growth method, the second heater has the highest temperature, the first heater's temperature is slightly lower than the second heater's, and the third heater's temperature is the lowest.

[0055] Advantages of this invention:

[0056] 1. Ring-shaped ampoule design improves wafer utilization; the ampoule adopts a ring structure, which can grow hollow cylindrical crystals and further prepare ring-shaped wafers; the wall thickness of the ring-shaped wafer is close to the long side of the target wafer, and multiple wafers can be obtained during dicing, which greatly improves material utilization and reduces waste.

[0057] 2. Internal heating design, energy-efficient and high-performance: The heater is placed inside the ampoule, replacing the traditional external heating method. During crystal growth, it works in conjunction with a refractory insulation material regulating center to concentrate heat on the crystal, reducing heat loss. Compared to traditional processes, it requires less power to reach the same temperature, significantly reducing energy consumption and making it more energy-efficient and environmentally friendly.

[0058] 3. Lightweight insulation structure simplifies the device; the heater is surrounded by an insulated top cover, an insulated base, and opaque materials such as frosted quartz, which effectively suppresses heat radiation leakage. Only a frosted quartz cover needs to be installed on the outside, eliminating the need for traditional thick insulation furnace walls, making the device simple in structure, low in cost, and light in weight.

[0059] 4. Visual observation window for easy process control: Since the heater is located inside and the heat radiation is blocked by the crystal, a transparent section can be reserved on the upper part of the quartz cover for easy observation, real-time monitoring of the growth of the crystal sidewall and the position of the solid-liquid interface, and improved process controllability.

[0060] 5. Dual-mode crystal growth strategy, flexible and efficient; Mode 1 (traditional vertical growth, i.e., bottom-up crystal growth): Adjusting the temperature of multiple heaters to advance the solid-liquid interface from bottom to top. Due to the thin wall and uniform temperature field, the growth rate can be greatly improved. Mode 2 (radial integral growth, i.e., outside-in crystal growth): Simultaneously reducing the temperature of multiple heaters to allow the crystal to grow from the outer wall to the inner wall as a whole. The speed is faster, and the growth direction can be flexibly selected according to the needs.

[0061] 6. Thin-walled structure optimization, high crystal uniformity; the crystal wall is thinner, the temperature difference between the inner and outer walls is smaller, the thermal stress is lower, the grown crystal structure is uniform, there are fewer defects, and the quality is stable.

[0062] 7. Rapid cooling technology improves production efficiency; after crystal growth, the regulating center is replaced with a high thermal conductivity ceramic heat dissipation material, which can achieve: uniform temperature field, reduce temperature difference in various parts of the crystal, reduce thermal stress; rapid cooling, accelerate heat removal, shorten process cycle, and improve overall efficiency.

[0063] In summary, this invention achieves high utilization, low energy consumption, high uniformity, high process flexibility, and high efficiency in crystal preparation through ring-shaped ampoule design, precise internal heating and temperature control, lightweight and efficient heat preservation, visualized real-time monitoring, dual-mode flexible growth, and rapid cooling technology. It significantly improves crystal growth efficiency, energy saving, and wafer utilization, and has significant application value in the fields of semiconductor, optics, and special crystal growth. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the crystal growth apparatus of the present invention.

[0065] Figure 2 This is a top view of the crystal growth apparatus of the present invention after the heat insulation top cover has been removed.

[0066] Figure 3 This is a schematic diagram showing the relationship between the inner surface of the ampoule and the outer surface of the heater in the crystal growth apparatus of the present invention.

[0067] Figure 4 This is a schematic diagram illustrating the geometric constraints between the ampoule size (i.e., crystal size) and the target wafer size of the present invention.

[0068] Figure 5 This is a schematic diagram of the crystal growth apparatus for Comparative Example 1.

[0069] Figure 6 The images show a comparison of the cross-sections of crystals grown under different conditions. (a) is a cross-section of the crystal grown in Example 1, (b) is a cross-section of the crystal grown in Comparative Example 1, (c) is a cross-section of the crystal grown in Example 2, and (d) is a cross-section of the crystal grown in Comparative Example 2.

[0070] Figure 7 The diagram shows a comparison of wafer utilization rates between the examples and the comparative examples, where (a) represents the number of wafers cut on the wafer of Comparative Example 1, and (b) represents the number of wafers cut on the wafer of Example 1.

[0071] The reference numerals are as follows: 1-First heater; 2-Second heater; 3-Third heater; 4-Crystal; 5-Ampoule; 6-Frosted quartz; 7-Insulated base; 8-Insulated support platform; 9-Frosted section; 10-Transparent section; 11-Insulated top cover; 12-Adjustment center. Detailed Implementation

[0072] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0073] Example 1

[0074] This embodiment provides a cadmium zinc telluride (Cd) with an inner diameter of 4.5 inches. 0.7 Zn 0.3 A crystal growth method for Te, comprising the following steps:

[0075] S1. Assembly of the charging and crystal growth apparatus

[0076] See Figure 1 and Figure 2Place the insulation base 7 on a horizontal platform. Support the first heater 1, second heater 2, and third heater 3 from top to bottom on the insulation base 7 using ceramic rods. Place the insulation support platform 8 on the insulation base 7 as well. Place the ampoule 5 containing the crystal growth material (clean the ampoule 5 first, then fill it with the zinc zinc cadmium crystal growth material, and then seal the ampoule 5) on the insulation support platform 8. Then place the frosted quartz 6 on the ampoule 5. Adjust the positions of all components to ensure they are completely coaxial. Place the frosted section 9 of the quartz cover on the insulation base 7, and place the transparent section 10 on top of the frosted section 9. Cover the top with the insulation top cover 11. Then insert the adjustment center 12, made of aluminum silicate insulation material, coaxially downwards through the center hole of the insulation top cover 11 until its bottom rests on the insulation base 7.

[0077] S2, Crystal Preparation

[0078] The crystal's melting point, Tm, is 1160℃. Following a pre-programmed heating process, the temperature of the first heater 1 reaches 1170℃, the second heater 2 reaches 1180℃, and the third heater 3 reaches 1160℃. At this point, a continuously changing temperature field exists between the second heater 2 and the third heater 3, with a point at which the temperature equals the crystal's melting point. Following the pre-programmed procedure, the temperature of the third heater 3 is gradually decreased, followed by the second heater 2, and finally the first heater 1. As the temperatures of the heaters in each section of the growth furnace gradually decrease in sequence, the temperature field within the furnace is dynamically adjusted synchronously. The isothermal surface equal to the crystal's melting point gradually moves from bottom to top, guiding the melt within the ampoule 5 to crystallize directionally from bottom to top, ultimately completing crystal growth.

[0079] S3. Cool down and remove the crystal.

[0080] After crystal growth, wearing high-temperature gloves, the regulating hub 12, which uses aluminosilicate insulation material, is removed. Then, the regulating hub 12, which uses alumina ceramic material, is inserted into the growth furnace, causing the temperature of each heater section to decrease from high temperature to room temperature according to the set time. Because the alumina ceramic regulating hub 12 has high thermal conductivity, a large amount of heat is dissipated from the growth furnace, resulting in a faster cooling rate, saving time and improving efficiency.

[0081] Example 2

[0082] This embodiment provides a method for growing cadmium telluride (CdTe) crystals with an inner diameter of 4.5 inches, which includes the following steps:

[0083] S1. Assembly of the charging and crystal growth apparatus

[0084] See Figure 1 and Figure 2Place the insulation base 7 on a horizontal platform. Support the first heater 1, second heater 2, and third heater 3 from top to bottom on the insulation base 7 using ceramic rods. Place the insulation support platform 8 on the insulation base 7 as well. Place the ampoule 5 containing the crystal growth material (clean the ampoule 5 first, then fill it with the cadmium telluride crystal growth material, and then seal the ampoule 5) on the insulation support platform 8. Then place the frosted quartz 6 on the ampoule 5. Adjust the positions of all components to ensure they are completely coaxial. Place the frosted section 9 of the quartz cover on the insulation base 7, and place the transparent section 10 on top of the frosted section 9. Cover the top with the insulation top cover 11. Then insert the adjustment center 12, made of aluminum silicate insulation material, coaxially downwards through the center hole of the insulation top cover 11 until its bottom rests on the insulation base 7.

[0085] S2, Crystal Preparation

[0086] First, according to the method of this invention, each crystal growth parameter is confirmed. The target wafer cross-sectional size is 20×20mm. 2 Therefore, a = 20 mm, b = 20 mm, and taking D1 = 76 mm, we can calculate D2 = 118 mm, and thus dc = 21 mm. The crystal's thermal conductivity k = 1.8 W / (m·K), and heat flux density q = 857.1 W / m³. 2 The crystal melting point Tm = 1160℃, and the high temperature Th inside the growth furnace can be calculated to be 1170℃. These are the crystal growth parameters for this method.

[0087] The temperature is increased according to the set program until the temperature of the first heater 1, the second heater 2, and the third heater 3 all reach 1170℃. At this point, a uniform constant temperature field is achieved within the heaters, while the ampoule 5 experiences a continuously changing temperature field from the inside out, with the outer surface temperature slightly higher than the crystal melting point. Simultaneously, the temperatures of the first heater 1, the second heater 2, and the third heater 3 are slowly decreased according to the set program. As the temperature of each heater section in the growth furnace gradually decreases, the temperature field within the ampoule 5 is dynamically adjusted synchronously. When the outer surface temperature of the ampoule 5 drops to the crystal melting point, the melt will crystallize directionally from the outside in, ultimately completing crystal growth.

[0088] S3. Cool down and remove the crystal.

[0089] After crystal growth, wearing high-temperature gloves, the regulating hub 12, which uses aluminum silicate insulation material, is removed. Then, the regulating hub 12, which uses high thermal conductivity ceramic material, is inserted into the growth furnace, causing the temperature of each heater section to decrease from high temperature to room temperature according to the set time. Because of the use of the high thermal conductivity regulating hub 12, a large amount of heat is dissipated from the growth furnace, resulting in a faster cooling rate, saving time and improving efficiency.

[0090] Comparative Example 1

[0091] The comparative example provides a 3-inch cadmium zinc telluride (Cd) 0.7 Zn 0.3 A crystal growth method for Te, comprising the following steps:

[0092] S1. Assembly of the charging and crystal growth apparatus

[0093] The insulation base 7 is placed on a horizontal platform. The first heater 1, the second heater 2, and the third heater 3 are stably supported on the insulation base 7 from top to bottom by ceramic rods. In this comparative example, the insulation support platform 8 is a bottomless cylindrical shape with the same total height as the first heater 1, the second heater 2, and the third heater 3. The insulation support platform 8 is placed on the insulation base 7 as the insulation structure of the growth furnace. The crystal growth apparatus is as follows: Figure 5 As shown, ampoule 5 has a cylindrical structure, and the grown crystal is a solid cylindrical structure without a central adjustment mechanism. Ampoule 5, containing the crystal growth material (first, ampoule 5 is cleaned, then the zinc cadmium telluride crystal growth material is loaded into ampoule 5, and then ampoule 5 is sealed), is stably supported on the insulating base 7. At this time, ampoule 5 is located inside the first heater 1, the second heater 2, and the third heater 3. The positions of all components are adjusted to ensure they are completely coaxial, and finally, the insulating top cover 11 is placed on top.

[0094] S2, Crystal Preparation

[0095] The temperature is increased according to the set program, eventually reaching 1170℃ for the first heater 1, 1180℃ for the second heater 2, and 1160℃ for the third heater 3. At this point, a continuously changing temperature field exists between the second heater 2 and the third heater 3, with the temperature at one point exactly equal to the crystal's melting point. Following the set program, the temperature of the third heater 3 is gradually decreased first, then the temperature of the second heater 2, and finally the temperature of the first heater 1. As the temperatures of the heaters in each section of the growth furnace gradually decrease in sequence, the melt in the ampoule 5 gradually crystallizes, ultimately completing crystal growth.

[0096] S3. Cool down and remove the crystal.

[0097] After crystal growth is complete, the temperature of each heater section is reduced from high temperature to room temperature according to the set time. Since the entire perimeter of the growth furnace is insulated, the cooling rate will be relatively slow, requiring patience.

[0098] Comparative Example 2

[0099] This comparative example provides a method for growing 3-inch cadmium telluride (CdTe) crystals, which includes the following steps:

[0100] S1. Assembly of the charging and crystal growth apparatus

[0101] The insulation base 7 is placed on a horizontal platform. The first heater 1, the second heater 2, and the third heater 3 are stably supported on the insulation base 7 from top to bottom by ceramic rods. In this comparative example, the insulation support platform 8 is a bottomless cylindrical shape with the same total height as the first heater 1, the second heater 2, and the third heater 3. The insulation support platform 8 is placed on the insulation base 7 as the insulation structure of the growth furnace. The crystal growth apparatus is as follows: Figure 5 As shown, ampoule 5 has a cylindrical structure, and the grown crystal is a solid cylindrical structure without a central adjustment mechanism. Ampoule 5, containing the crystal growth material (first, ampoule 5 is cleaned, then the cadmium telluride crystal growth material is placed inside, and then ampoule 5 is sealed), is stably supported on the insulating base 7. At this time, ampoule 5 is located inside the first heater 1, the second heater 2, and the third heater 3. The positions of all components are adjusted to ensure they are completely coaxial, and finally, the insulating top cover 11 is placed on top.

[0102] S2, Crystal Preparation

[0103] The temperature is increased according to the set program, eventually reaching 1160℃ for the first heater 1, 1170℃ for the second heater 2, and 1160℃ for the third heater 3. At this point, a continuously changing temperature field exists between the second heater 2 and the third heater 3, with the temperature at one point exactly equal to the crystal's melting point. Following the set program, the temperature of the third heater 3 is gradually decreased first, then the temperature of the second heater 2, and finally the temperature of the first heater 1. As the temperatures of the heaters in each section of the growth furnace gradually decrease in sequence, the melt in the ampoule 5 gradually crystallizes, ultimately completing the entire crystal growth process.

[0104] S3. Cool down and remove the crystal.

[0105] After crystal growth is complete, the temperature of each heater section is reduced from high temperature to room temperature according to the set time. Since the entire perimeter of the growth furnace is insulated, the cooling rate will be relatively slow, requiring patience.

[0106] To verify the effectiveness of the invention, the following tests were also conducted.

[0107] I. Comparison of Crystal Growth Quality and Wafer Utilization

[0108] Take the crystals grown in Examples 1-2 and Comparative Examples 1-2, and cut circular slices of the same thickness along the vertical axis. The results are as follows. Figure 6 As shown, where, Figure 6 Images (a), (b), (c), and (d) show the wafer results for Example 1, Comparative Example 1, Example 2, and Comparative Example 2, respectively. Figure 6As can be seen from the data, the crystals in Examples 1 and 2 have a uniform color on the entire annular surface and no grain boundaries are visible, indicating that they are complete single crystals; while the crystals in Comparative Examples 1 and 2 clearly show some grain boundaries, indicating that polycrystalline structures have been formed.

[0109] With a target cross-sectional size of 20×20mm 2 Taking the wafer as an example, the number of wafers diced in Examples 1-2 and Comparative Examples 1-2 is compared, and the results are as follows: Figure 7 As shown. From Figure 7 As can be seen from (a) and (b), the number of wafers cut in Example 1 is much greater than the number of wafers cut in Comparative Example 1.

[0110] II. Comparison of Crystal Production Efficiency

[0111] Using the same weight of raw material (6000 g each), crystal growth was completed according to the schemes of Examples 1-2 and Comparative Examples 1-2, respectively. Then, all crystals were cut into pieces with a target cross-sectional size of 20×20 mm. 2 The number of chips was then counted, and the results are shown in Table 1.

[0112] Table 1 Comparison of the number of wafers in the examples and comparative examples

[0113]

[0114] The comparison results of Examples 1-2 and Comparative Examples 1-2 show that, by using the method of the present invention, since the crystal wall thickness is much smaller than the 3-inch crystal diameter, the temperature field inside the crystal is more uniform, the single crystal rate of the grown crystal is significantly improved, and the overall uniformity of the crystal is also better due to the absence of polycrystalline grain boundaries.

[0115] Furthermore, it is evident that the number of target wafers cut from a single wafer in Examples 1-2 is significantly greater than that in Comparative Examples 1-2, which greatly improves production efficiency. Simultaneously, with the same weight of raw materials, Examples 1-2 also produce more wafers than Comparative Examples 1-2, demonstrating a significant improvement in raw material utilization.

[0116] In summary, the crystal growth apparatus designed in this invention can balance temperature uniformity and production efficiency, while improving wafer utilization and crystal growth efficiency, and has a promising application prospect.

[0117] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A crystal growth device, comprising: a growth furnace, a regulating core, a heater, and an ampoule; the growth furnace is cylindrical in shape, comprising a heat preservation base, a quartz cover, and a heat preservation top cover which are coaxially installed in sequence from bottom to top; the regulating core is cylindrical in shape, coaxially inserted into the growth furnace, and forms an annular crystal growth cavity with the quartz cover, with the top end extending out of the heat preservation top cover; the regulating core comprises two types, namely a regulating core for heat preservation in a crystal growth stage and a regulating core for heat conduction in a cooling stage; in the crystal growth stage, the material of the regulating core is a refractory heat preservation material with a thermal conductivity of ≤0.5 W / (m·K); in the cooling stage, the material of the regulating core is a ceramic material with a thermal conductivity of ≥2 W / (m·K); the heater is stably supported in the annular crystal growth cavity and is sleeved outside the regulating core with a distance between the heater and the regulating core, and the heater is a three-section heater comprising a first heater, a second heater, and a third heater from top to bottom, all of which are made of spiral resistance wires and are stably supported in the annular crystal growth cavity by ceramic rods; the ampoule is circular in cross-section, and the top and bottom thereof are stably installed between the heater and the quartz cover by ground quartz and a heat preservation support platform, respectively; the quartz cover is divided into two parts from top to bottom, wherein the upper part is a transparent section, and the lower part is a ground section, and the top of the ground section is higher than the top of the ampoule. 2.The crystal growth device according to claim 1, wherein: the material of the ampoule is high-purity quartz. 3.The crystal growth device according to claim 2, wherein: the upper end and the lower end of the heater are at least D h longer than the top and the bottom of the ampoule, respectively, and the heater satisfies L h ≥ L c + 2 D h, wherein L h is the total height of the heater, L c is the height of the ampoule, and D h is the inner diameter of the heater. 4.The crystal growth device according to claim 3, wherein: 5.The crystal growth device according to claim 4, wherein: the length by which the top of the ground section is higher than the top of the ampoule is greater than or equal to D 2 and less than or equal to 2 D 2. 6.The crystal growth device according to any one of claims 3-5, wherein: the top of the regulating core extends out of the heat preservation top cover by at least 2 D h. 7.The crystal growth device according to claim 2, wherein: the spiral resistance wire is an iron-chromium-aluminum resistance wire; in the crystal growth stage, the material of the regulating core is an aluminum silicate heat preservation fiber; in the cooling stage, the material of the regulating core is an alumina ceramic; and the heat preservation base, the heat preservation support platform, and the heat preservation top cover are all made of aluminum silicate heat preservation material. 8.The crystal growth device according to claim 2, wherein: the diameter of the spiral resistance wire is at least 10 mm. including the following steps: S1. installing the heat preservation base, the heat preservation support platform, and the heater in place; S2. supporting the ampoule containing crystal raw materials on the heat preservation base through the heat preservation support platform; The distance between the inner surface of the ampoule and the outer surface of the heater is denoted as L ah with the value range of 2S≤L ah ≤5S, wherein S is the pitch of the spiral resistance wire. S3. placing ground quartz on the top of the ampoule and surrounding the quartz cover with the quartz cover; S4. installing the heat preservation top cover in place; and The geometric constraint between the ampoule size and the target wafer size is: (a / 2) 2 +(D1 / 2+b) 2 =(D2 / 2) 2 and dc = (D2-D1) / 2; where D1 is the inner diameter of the ampoule annular cavity, D2 is the outer diameter of the ampoule annular cavity, dc is the thickness of the ampoule annular cavity, and a and b are the length of the short side and long side of the target wafer, respectively. S5. performing crystal growth. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 9. A method for growing a crystal using the crystal growing apparatus according to any one of claims 1 to 8, characterized by, ​ ​ ​ ​ ​ S5. In the crystal growth stage, the adjusting hub made of refractory insulation material is coaxially inserted into the growth furnace, the heater temperature is adjusted according to the crystal growth mode, and the crystal growth is carried out; The crystal growth mode is from bottom to top or from outside to inside; S6. In the cooling stage after the crystal growth, the adjusting hub made of heat-conducting material is used to replace the adjusting hub made of refractory insulation material for cooling, and finally the crystal is obtained.

10. The method of claim 9, wherein: In S5, for the crystal growth mode from outside to inside, the adjustment basis of the highest temperature of the heater is Th-Tm=q·dc / k, wherein Tm is the melting point of the crystal; Th is the highest temperature of the heater; dc is the thickness of the annular cavity of the ampoule; k is the thermal conductivity of the crystal; and q is the heat flux density.

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