A method for controlling an external traveling wave magnetic field suitable for growing indium phosphide single crystals

Abstract

The present invention discloses a method for controlling an external traveling-wave magnetic field suitable for growing indium phosphide single crystals. A traveling-wave magnetic field is applied to the exterior of a metal furnace wall of an indium phosphide single crystal growth furnace. The magnetic field frequency is adjusted based on furnace wall parameters, including wall material, thickness, and whether the wall is solid or hollow, to maximize the Lorentz force in the indium phosphide melt. The traveling-wave magnetic field is generated by arranging several parallel sets of coils on the exterior of the metal furnace wall and sequentially passing sinusoidal alternating current through the coils. While taking into account the electromagnetic shielding effect of the metal furnace wall of the indium phosphide single crystal growth furnace, the method adjusts the magnetic field frequency based on the furnace wall material, thickness, and internal structure parameters to maximize the Lorentz force in the indium phosphide melt. This method can fully utilize the electromagnetic stirring effect of the traveling-wave magnetic field, effectively controlling melt flow, temperature distribution, and crystallization interface shape, thereby facilitating the growth of high-quality indium phosphide single crystals.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal growth and material smelting control, and in particular relates to a method for controlling an external traveling wave magnetic field suitable for growing indium phosphide single crystals. Background Art

[0002] Indium phosphide single crystals are crucial compound semiconductor materials with significant application value in the semiconductor field. The flow of the melt during the growth of InP single crystals influences key crystal growth parameters such as temperature distribution, crystallization interface shape, and impurity transport. Controlling melt flow is crucial for growing high-quality InP single crystals. Because InP melts have a certain degree of conductivity, magnetic fields can be used to actively control melt flow.

[0003] Magnetic fields can be categorized as static or dynamic, depending on whether they vary over time. Static magnetic fields, including horizontal, vertical, and elliptical magnetic fields, are typically used to suppress violent melt flow. Dynamic magnetic fields, including traveling and rotating magnetic fields, are typically used to actively control melt flow. The Lorentz force generated by a traveling magnetic field can suppress or enhance natural convection in the melt by adjusting its direction, and has therefore attracted widespread attention in the field of crystal growth.

[0004] The energized coils that generate the traveling-wave magnetic field are typically placed outside the crystal growth furnace. This allows for independent control of the magnetic field generator and the furnace, allowing for greater autonomy in the design of magnetic field parameters. However, due to the relatively low electrical conductivity of the indium phosphide melt and the relatively high electrical conductivity of the metal furnace wall, the electromagnetic shielding effect of the furnace wall on the traveling-wave magnetic field cannot be ignored. Previous studies have often focused solely on the mechanism of the traveling-wave magnetic field under the shielding effect of the metal furnace wall, making the results difficult to apply in production practice.

[0005] In the prior art, the authorized patent "A traveling wave magnetic field control method suitable for crystal growth process (patent number: CN202011080122.8)" mainly focuses on "controlling the melt flow by modulating the traveling wave magnetic field parameters in different crystal growth stages, thereby improving the temperature distribution, crystallization interface shape and impurity distribution." It does not involve the traveling wave magnetic field control of indium phosphide single crystal growth facing electromagnetic shielding, which is the focus of this patent application. How to adjust the magnetic field frequency according to the furnace wall parameters so that the Lorentz force in the indium phosphide melt reaches the maximum value range. Summary of the Invention

[0006] The object of the present invention is to provide a method for controlling an external traveling wave magnetic field suitable for the growth of indium phosphide single crystals. The method, while taking into account the electromagnetic shielding effect of the metal furnace wall of the indium phosphide single crystal growth furnace, adjusts the magnetic field frequency according to the furnace wall material, thickness and internal structural parameters, so that the Lorentz force in the indium phosphide melt reaches a maximum range, and can fully utilize the electromagnetic stirring effect of the traveling wave magnetic field, thereby efficiently controlling the melt flow, temperature distribution and crystallization interface shape, thereby facilitating the growth of high-quality indium phosphide single crystals.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for controlling an external traveling wave magnetic field suitable for the growth of indium phosphide single crystals, wherein a traveling wave magnetic field is applied to the outer side of the metal furnace wall of an indium phosphide single crystal growth furnace, and the magnetic field frequency is adjusted according to the furnace wall parameters, such that the Lorentz force in the indium phosphide melt reaches a maximum value range. The furnace wall parameters include the material, thickness, and internal structure of the furnace wall, whether it is solid or hollow.

[0008] The material of the metal furnace wall is stainless steel, the thickness t of the furnace wall ranges from 40 to 60 mm, the internal structure of the furnace wall is solid or hollow, and the corresponding hollow gap range is (0 to 0.6) t.

[0009] When the thickness of the hollow gap inside the furnace wall is (0-0.2)t, the frequency range of the traveling wave magnetic field is 50-200Hz.

[0010] When the thickness of the hollow gap inside the furnace wall is (0.2-0.4)t, the frequency range of the traveling wave magnetic field is 50-300Hz.

[0011] When the thickness of the hollow gap inside the furnace wall is (0.4-0.6)t, the frequency range of the traveling wave magnetic field is 50-400Hz.

[0012] During the crystal growth process, the traveling wave magnetic field is used to control the melt flow, temperature distribution and crystallization interface shape in real time.

[0013] The traveling wave magnetic field is generated by arranging several sets of parallel coils on the outside of the metal furnace wall and sequentially passing sinusoidal alternating current through the coils.

[0014] There are 3 to 6 coils in total, and all coils form a coil group. The total height of the coil group is 1-10 times the height of the melt, and the range of 1 / 4 to 3 / 4 of the total height of the coil group is the melt placement area.

[0015] The current is alternating current, and there is a phase difference between the currents passing through adjacent coils, and the phase difference range is -120°-120°.

[0016] The present invention has at least the following beneficial technical effects:

[0017] While taking into account the electromagnetic shielding effect of the metal furnace wall of the indium phosphide single crystal growth furnace, the magnetic field frequency is adjusted according to the furnace wall material, thickness and internal structural parameters, so that the Lorentz force in the indium phosphide melt reaches the maximum value range, and the electromagnetic stirring effect of the traveling wave magnetic field can be fully utilized, thereby efficiently controlling the melt flow, temperature distribution and crystallization interface shape, thereby facilitating the growth of high-quality indium phosphide single crystals. At the same time, the present invention can generate a relatively strong Lorentz force at a relatively low magnetic field current intensity, so that the efficiency of the magnetic field is maximized, which is beneficial to energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the indium phosphide single crystal growth melt area, metal furnace wall and traveling wave magnetic field generating coil.

[0019] Figure 2 This is the curve of the maximum Lorentz force in the indium phosphide melt changing with the magnetic field frequency when the stainless steel metal furnace wall thickness is 50mm and the middle gap is 0mm (solid), 10mm, 20mm, and 30mm.

[0020] Figure 3 The temperature distribution, velocity distribution and crystallization interface shape of the indium phosphide melt and crystal area when the stainless steel metal furnace wall thickness is 50mm, the middle gap is 10mm, the downward traveling magnetic field frequency is 100Hz, and the crystallization height is 50%.

[0021] Figure 4 The temperature and velocity distributions of the indium phosphide melt region when it is about to crystallize are shown in the following figure: the stainless steel metal furnace wall is 50 mm thick, the middle gap is 30 mm, the downward traveling magnetic field frequency is 200 Hz, and the temperature and velocity distributions are shown in the figure. DETAILED DESCRIPTION

[0022] When considering the effects of a traveling wave magnetic field on the shielding effect of the metal furnace wall in an indium phosphide single crystal growth furnace, the magnetic field parameters need to be designed in conjunction with the furnace wall's material, thickness, and internal structural parameters. On the one hand, the Lorentz force in the melt increases with increasing magnetic field frequency. On the other hand, the electromagnetic shielding effect of the metal furnace wall causes the Lorentz force in the melt to decrease with increasing magnetic field frequency. The combined effect of these two factors results in an optimal frequency range for specific furnace wall material, thickness, and internal structure conditions. Within this range, the Lorentz force in the melt reaches its maximum value, fully utilizing the electromagnetic stirring effect of the traveling wave magnetic field. These characteristics have not been reflected in previous research and patents.

[0023] The present invention provides a method for controlling an external traveling wave magnetic field suitable for growing an indium phosphide single crystal. The method applies a traveling wave magnetic field to the outside of a metal furnace wall of an indium phosphide single crystal growth furnace, and adjusts the magnetic field frequency according to furnace wall parameters, such that the Lorentz force in the indium phosphide melt reaches a maximum value. The furnace wall parameters include the material and thickness of the furnace wall, and whether the internal structure is solid or hollow.

[0024] The traveling wave magnetic field is generated by arranging several parallel groups of coils on the outside of a metal furnace wall and sequentially passing sinusoidal alternating current through the coils. The metal furnace wall is made of stainless steel, has a furnace wall thickness t ranging from 40 to 60 mm, and has a solid or hollow internal structure with a corresponding hollow gap range of (0 to 0.6) t. When the hollow gap thickness inside the furnace wall is (0-0.2) t, the traveling wave magnetic field frequency range is 50-200 Hz; when the hollow gap thickness inside the furnace wall is (0.2-0.4) t, the traveling wave magnetic field frequency range is 50-300 Hz; and when the hollow gap thickness inside the furnace wall is (0.4-0.6) t, the traveling wave magnetic field frequency range is 50-400 Hz.

[0025] The present invention is further described below with reference to the accompanying drawings and embodiments:

[0026] Example 1:

[0027] In this embodiment, under the conditions of a stainless steel furnace wall thickness of 50 mm and a central gap of 10 mm, a traveling wave magnetic field frequency of 100 Hz is selected to achieve efficient control of melt flow, temperature distribution and crystallization interface shape.

[0028] See also Figure 1 Schematic diagram of the indium phosphide single crystal growth melt, metal furnace walls, and traveling-wave magnetic field generating coils. The center is the indium phosphide melt, surrounded by the hollow metal furnace walls. The outermost coils are the six energized coils that generate the traveling-wave magnetic field. Figure 2 The maximum Lorentz force in an indium phosphide melt varies with magnetic field frequency when the metal furnace wall is made of stainless steel and has a thickness of 50mm. The maximum Lorentz force in the melt decreases with increasing frequency when the gap is 0mm (solid), 10mm, 20mm, and 30mm. However, for gaps of 10mm, 20mm, and 30mm, the force first increases and then decreases with increasing frequency. The maximum Lorentz force corresponds to different magnetic field frequencies for different gaps. For a gap of 10mm, the maximum Lorentz force in the melt corresponds to a magnetic field frequency of 100Hz. Figure 3 The temperature distribution, velocity distribution, and crystallization interface shape of the indium phosphide melt and crystal region are shown when the stainless steel metal furnace wall thickness is 50mm, the central gap is 10mm, the downward traveling magnetic field frequency is 100Hz, and the crystallization height is 50%. Among them, the left side of the figure is the temperature distribution, the upper right side is the velocity vector of the melt flow, and the middle is the crystallization interface and the isotherm corresponding to the solidification point of 1062℃ in the melt. It can be found that the traveling magnetic field affects the melt flow, and thus affects the temperature distribution and the shape of the crystallization interface, so that the isotherms and crystallization interfaces near the solidification point maintain a slightly convex shape, which is conducive to the growth of large-sized indium phosphide single crystals and improves the crystal quality.

[0029] Example 2:

[0030] In this embodiment, under the conditions of a stainless steel furnace wall thickness of 50 mm and a hollow gap of 30 mm, a traveling wave magnetic field frequency of 200 Hz is selected to achieve efficient control of melt flow and temperature distribution.

[0031] See also Figure 2 , for the case where the hollow gap is 30 mm, the maximum Lorentz force in the melt corresponds to a magnetic field frequency of 200 Hz. Figure 4 The temperature and velocity distributions of an indium phosphide melt near crystallization are shown in a stainless steel furnace with a 50mm thick wall, a 30mm hollow gap, and a downward traveling magnetic field at a frequency of 200Hz. The left side of the figure shows the temperature distribution, while the right side shows the velocity vector of the melt flow. The bottom of the melt is 1063°C, slightly above the crystallization point of 1062°C. It can be seen that the traveling magnetic field affects the melt flow, which in turn affects the temperature distribution, resulting in a slightly convex isotherm, which is conducive to growing large indium phosphide single crystals and improving crystal quality.

Claims

1. A method for controlling an external traveling wave magnetic field for growing an indium phosphide single crystal, characterized in that: A traveling wave magnetic field is applied to the outer side of a metal furnace wall of an indium phosphide single crystal growth furnace, and the magnetic field frequency is adjusted according to furnace wall parameters so that the Lorentz force in the indium phosphide melt reaches a maximum value range. The furnace wall parameters include the furnace wall material, thickness, and internal structure (solid or hollow). The metal furnace wall is made of stainless steel, the furnace wall thickness t ranges from 40 to 60 mm, the furnace wall internal structure is solid or hollow, and the corresponding hollow gap range is (0 to 0.6) t. When the hollow gap thickness inside the furnace wall is (0-0.2) t, the traveling wave magnetic field frequency ranges from 50 to 200 Hz; when the hollow gap thickness inside the furnace wall is (0.2-0.4) t, the traveling wave magnetic field frequency ranges from 50 to 300 Hz; and when the hollow gap thickness inside the furnace wall is (0.4-0.6) t, the traveling wave magnetic field frequency ranges from 50 to 400 Hz.

2. The method for controlling an external traveling wave magnetic field suitable for growing an indium phosphide single crystal according to claim 1, characterized in that: During the crystal growth process, the traveling wave magnetic field is used to control the melt flow, temperature distribution and crystallization interface shape in real time.

3. The method for controlling an external traveling wave magnetic field suitable for growing an indium phosphide single crystal according to claim 1, characterized in that: The traveling wave magnetic field is generated by arranging several sets of parallel coils on the outside of the metal furnace wall and sequentially passing sinusoidal alternating current through the coils.

4. The method for controlling an external traveling wave magnetic field suitable for growing an indium phosphide single crystal according to claim 3, characterized in that: There are 3 to 6 coils in total, and all coils form a coil group. The total height of the coil group is 1-10 times the height of the melt, and the range of 1 / 4 to 3 / 4 of the total height of the coil group is the melt placement area.

5. The method for controlling an external traveling wave magnetic field suitable for growing an indium phosphide single crystal according to claim 3, characterized in that: The current is alternating current, and there is a phase difference between the currents passing through adjacent coils, and the phase difference range is -120°-120°.

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