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WO-2026091963-A1 - APPARATUS AND METHOD FOR GROWING CYLINDRICAL SILICON CARBIDE SINGLE CRYSTAL BY LIQUID PHASE METHOD

WO2026091963A1WO 2026091963 A1WO2026091963 A1WO 2026091963A1WO-2026091963-A1

Abstract

The present invention relates to the technical field of preparation of silicon carbide single crystals, and in particular to an apparatus and method for growing a cylindrical silicon carbide single crystal by a liquid phase method. The apparatus comprises a heat dissipation control apparatus arranged above a silicon carbide seed crystal, the heat dissipation control apparatus comprising six edges each having an angle of 60° and equal lengths. The end points of each edge away from the center are connected by a circular arc recessed toward the center. Different edges are connected by downwardly concave curved surfaces. The portions at which the edges are located have the greatest thickness, and heat dissipation is the slowest. The positions of bisectors of angles formed by two adjacent edges have the smallest thickness, and heat dissipation is the fastest. The crystal orientation of the seed crystal is controlled to be consistent with the directions of the edges, and the crystal orientation of the seed crystal is consistent with the bisectors of the angles formed by two adjacent edges. The present invention provides an apparatus and method for growing a cylindrical silicon carbide single crystal by a liquid phase method, which can effectively suppress anisotropy of the growth rate of silicon carbide crystals during liquid phase growth, and prepare a cylindrical silicon carbide crystal, thereby reducing the difficulty and costs of wafer processing.

Inventors

  • WANG, GUOBIN
  • ZHANG, Zesheng

Assignees

  • 北京晶格领域半导体有限公司

Dates

Publication Date
20260507
Application Date
20250919
Priority Date
20241031

Claims (9)

  1. An apparatus for growing cylindrical silicon carbide crystals by liquid phase method is characterized by including a heat dissipation control device (11) installed above a silicon carbide seed crystal (7). The heat dissipation control device (11) is thick in the middle and thin around the edges, and has an anisotropic structure with six-fold symmetry. It includes six edges with an included angle of 60° and equal length. The endpoints of each edge away from the center are connected by a concave arc towards the center. Different edges are connected by a downward concave curved surface. The thickness of the part where the edge is located is the largest and the heat dissipation rate is the smallest at the same distance from the center of the heat dissipation control device (11). The thickness of the part where the angle bisector of the angle formed by two adjacent edges is the smallest and the heat dissipation rate is the largest. The heat dissipation control device is installed with a fixed correspondence to the crystal orientation of the silicon carbide seed crystal. The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisector of the two adjacent edges.
  2. The device according to claim 1 is characterized in that the vertical projection of the arc is tangent to the vertical projection of the seed crystal (7).
  3. According to claim 1, the device is characterized in that, with the center of the heat dissipation control device (11) as the center and the distance between the axis of the heat dissipation control device (11) and the midpoint of the arc as the radius, a reference circle is drawn within the range of the reference circle. In the portion of the same length from the axis of the heat dissipation control device (11), the thickness ratio of the edge to the thickness at the bisector of the adjacent edge is 2:1 to 10:1. Outside the range of the reference circle, the thickness decreases to 1 to 5 mm in the direction away from the edge and away from the center of the reference circle.
  4. The device according to claim 1 is characterized in that it further includes a first rotating lifting shaft (1), a seed crystal holder (5) and a locking sleeve (12), the first rotating lifting shaft (1) is used for lifting and rotating, the lower part of the seed crystal holder (5) is connected to the seed crystal (7), the upper part of the seed crystal holder (5) is provided with a connecting shaft, the connecting shaft passes through the through hole at the center of the heat dissipation control device (11) and is detachably connected to the first rotating lifting shaft (1), the heat dissipation control device and the seed crystal holder rotate and lift synchronously under the drive of the rotating lifting rod.
  5. According to claim 4, the device is characterized in that the connecting shaft passes through the through hole in the middle position of the heat dissipation control device (11) and is snap-connected to the first rotating lifting shaft (1), and the locking sleeve (12) is sleeved on the first rotating lifting shaft (1), and the locking sleeve (12) is used to lock the snap-connection between the connecting shaft and the first rotating lifting shaft (1).
  6. The apparatus according to claim 1 is characterized in that it further includes a growth furnace (2) and a growth crucible (4) located in the growth furnace (2), wherein an induction coil (6) for heating is provided in the growth furnace (2), the growth crucible (4) is filled with high-temperature melt (8), the growth crucible (4) is wrapped with heat-insulating material (3), a crucible support plate (9) is provided at the bottom, and a second rotating lifting shaft (10) for lifting and rotating is provided at the bottom of the crucible support plate (9).
  7. The apparatus according to claim 6 is characterized in that the growth crucible (4) is a graphite crucible, and the composition and ratio of the high-temperature melt (8) in the growth crucible (4) is: Si:Cr:Cu:Al＝70:20:5:5.
  8. A method for growing cylindrical silicon carbide crystals using a liquid-phase method, characterized in that, based on the apparatus according to any one of claims 1-7, the method comprises: The heat dissipation control device (11) is provided above the seed crystal (7); Adjust the positional relationship between the heat dissipation control device (11) and the seed crystal (7) so that the silicon carbide seed crystal... The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisector of two adjacent edges; The liquid phase method was used to grow silicon carbide crystals.
  9. According to the method described in claim 8, the growth temperature of the liquid-phase silicon carbide crystal is 1700–1900 °C.

Description

An apparatus and method for growing cylindrical silicon carbide single crystals by liquid phase method Technical Field This invention relates to the field of silicon carbide single crystal preparation technology, and particularly to an apparatus and method for growing cylindrical silicon carbide single crystals by liquid phase method. Background Technology Silicon carbide, as a typical representative of wide bandgap semiconductors, has excellent properties such as large bandgap, high breakdown field strength, high saturated electron mobility, high thermal conductivity, and good thermal and chemical stability. It is an ideal substrate material for fabricating high-frequency, high-voltage, high-efficiency, radiation-resistant, and high-temperature-resistant high-power devices and blue light-emitting diodes. This makes it a promising material for applications in new energy vehicles, high-speed rail, aerospace, high-voltage smart grids, and clean energy, and has therefore attracted widespread attention from the academic community and governments around the world. Liquid-phase growth is an important method for preparing silicon carbide single crystals. It requires low growth temperatures, provides a relatively stable growth environment, and allows for near-equilibrium crystal growth. This not only results in relatively low growth costs but also theoretically enables higher crystal quality. Furthermore, the liquid-phase method shows promising applications in obtaining P-type substrates and crystal diameter expansion. Therefore, the liquid-phase method has received increasing attention in recent years, and related technologies have made significant breakthroughs. In the liquid-phase growth of silicon carbide single crystals, the strong anisotropy of the solid-liquid interface energy between the silicon carbide crystal and the high-temperature solution is a crucial factor. The solid-liquid interfacial energy between crystal planes and high-temperature solutions is much lower than The solid-liquid interface energy between the crystal plane family and the high-temperature solution. Therefore, when the crystal grows in the liquid phase, along... The growth rate in the direction of growth is much greater than that along the direction of growth. The directional growth rate ultimately leads to the crystal easily developing into a hexagonal shape. Hexagonal crystals are difficult and costly to process into wafers, and are prone to cracking, which can cause crystal breakage. Therefore, developing a device that can grow cylindrical SiC crystals through liquid phase is of great significance. Summary of the Invention This invention provides an apparatus and method for growing cylindrical silicon carbide single crystals using a liquid-phase method, which can prepare cylindrical silicon carbide crystals. In a first aspect, embodiments of the present invention provide an apparatus for growing cylindrical silicon carbide crystals using a liquid-phase method, including a heat dissipation control device mounted above a silicon carbide seed crystal. The heat dissipation control device is thick in the middle and thin around the edges, and has an anisotropic structure with six-fold symmetry. It includes six edges with an included angle of 60° and equal length. The endpoints of each edge away from the center are connected by a concave arc towards the center, and different edges are connected by a downward concave curved surface. This makes the part where the edge is located at the same distance from the center of the heat dissipation control device have the greatest thickness and the smallest heat dissipation rate. The part where the angle bisector of two adjacent edges is located has the smallest thickness and the largest heat dissipation rate. The heat dissipation control device is installed with a fixed correspondence to the crystal orientation of the silicon carbide seed crystal. The crystal orientation and edge direction are consistent, and the silicon carbide seed crystal has the same direction. The crystal orientation coincides with the angle bisector of the two adjacent edges. In one possible design, the vertical projection of the arc is tangent to the vertical projection of the seed crystal. In one possible design, a reference circle is drawn with the center of the heat dissipation control device as the center and the distance between the axis of the heat dissipation control device and the midpoint of the arc as the radius. Within the range of the reference circle, in the portion of the same length from the axis of the heat dissipation control device, the ratio of the thickness of the edge to the thickness of the bisector of the adjacent edge is 2:1 to 10:1. Outside the range of the reference circle, the thickness decreases to 1 to 5 mm in the direction away from the edge and away from the center of the reference circle. In one possible design, it also includes a first rotating lifting shaft, a seed crystal holder, and a