Search

CN-121992485-A - Crystal growth apparatus and method

CN121992485ACN 121992485 ACN121992485 ACN 121992485ACN-121992485-A

Abstract

A crystal growth device and method are provided, wherein a silicon carbide thermal field system is arranged in a heat preservation chamber, the lower opening end of a support sleeve is lapped at the upper opening end of a crucible body, the gas leakage rate of a joint is positioned in a set leakage range I, a seed crystal cover is arranged at the upper opening end of the support sleeve and provided with air holes, a graphite cap and the heat preservation sleeve are distributed up and down, the graphite cap is arranged outside the support sleeve, the gas leakage rate at an annular joint of the graphite cap and the heat preservation sleeve is positioned in a set leakage range II, and the heat preservation sleeve is made of multi-layer graphite soft felt and is sleeved outside the crucible body. In the process of crystal growth, the leaked silicon-rich gas phase component is utilized to gradually corrode the heat preservation sleeve on the outer side of the crucible body, so that the heat preservation effect of the heat preservation sleeve on the bottom of the crucible body is gradually weakened, the high-temperature area is guided to move upwards, and the temperature gradient stability of the crystal growth area is ensured. The invention can obviously improve the utilization efficiency of the powder and realize the thickening and efficient growth of crystals.

Inventors

  • LI YUANTIAN
  • HAN QIAN
  • YIN LIANGLIANG
  • WU ANNAN
  • HU JIALE
  • LIU CHEN

Assignees

  • 江苏集芯先进材料有限公司

Dates

Publication Date
20260508
Application Date
20260126

Claims (10)

  1. 1. A crystal growth device, which comprises a thermal insulation chamber (1) and a silicon carbide thermal field system (22), and is characterized in that; The silicon carbide thermal field system (22) is arranged in the heat preservation chamber (1), and the silicon carbide thermal field system (22) comprises a crucible body (10), a support sleeve (2), a seed crystal cover (6), a heat preservation sleeve (3) and a graphite cap (8); The lower opening end of the supporting sleeve (2) is lapped at the upper opening end of the crucible body (10), and the gas leakage rate at the joint of the lower opening end and the crucible body is positioned in a set leakage range I; The seed crystal cover (6) is arranged at the upper opening end of the supporting sleeve (2) in a covering manner, a seed crystal installation area (13) is arranged in the center area of the lower end surface of the seed crystal cover, and an air passing hole (14) is formed in the periphery of the seed crystal installation area (13); The graphite caps (8) and the heat preservation sleeves (3) are distributed up and down, the graphite caps (8) are covered outside the support sleeve (2), the gas leakage rate at the annular joint of the graphite caps and the heat preservation sleeves is in a second leakage range, and the heat preservation sleeves (3) are sleeved outside the crucible body (10).
  2. 2. A crystal growth apparatus according to claim 1, wherein the silicon carbide thermal field system (22) further comprises: The support piece (4), the said support piece (4) is installed in the inboard of the upper end of the crucible body (10), and offer the bleeder vent (11); the graphite plate (5) is covered at the upper opening end of the crucible body (10) through the supporting piece (4), and a plurality of vent holes (12) are formed in the graphite plate (5); The flow guide component (7), the flow guide component (7) is arranged between the graphite plate (5) and the seed crystal installation area (13), the bottom of the flow guide component is connected with the edge of the graphite plate (5), and the flow guide component (7) and the graphite plate (5) jointly define a single crystal growth space.
  3. 3. The crystal growth apparatus of claim 2, wherein the silicon carbide thermal field system (22) further comprises graphite paper (24), the graphite paper (24) is attached to the top inner surface of the graphite cap (8), and the thermal insulation sleeve (3) is made of multi-layer graphite soft felt.
  4. 4. A crystal growth apparatus according to claim 2, wherein the flow guide member (7) is a flow guide cylinder which is of a truncated cone shape.
  5. 5. A crystal growth apparatus according to claim 1, further comprising a flexible felt ring (18), the flexible felt ring (18) being arranged between the junction of the support sleeve (2) and the crucible body (10).
  6. 6. A crystal growth apparatus according to claim 1, wherein, The support sleeve (2) is made of graphite, an annular concave table (17) is arranged on the inner side of the lower end of the support sleeve, and the annular concave table (17) is sleeved on the outer side of the upper end of the crucible body (10) through threaded fit.
  7. 7. A crystal growth apparatus according to claim 1, wherein the support sleeve (2) is connected to the graphite cap (8) by a screw-fit.
  8. 8. A crystal growth apparatus according to claim 1, characterized in that the holding chamber (1) is provided with temperature measuring holes (9).
  9. 9. A crystal growth apparatus according to claim 8, wherein the insulating chamber (1) comprises an insulating cylinder (19), an insulating base (20) and an insulating cover (21), and the insulating base (20) and the insulating cover (21) are respectively sealed at an upper opening end and a lower opening end of the insulating cylinder (19).
  10. 10. A crystal growth method using a crystal growth apparatus according to any one of claims 1 to 9, comprising the steps of: In the growth process of the crystal (16), the leaked silicon-rich gas phase component is utilized to gradually corrode the heat preservation sleeve (3) on the outer side of the crucible body (10), so that the heat preservation effect of the heat preservation sleeve (3) on the bottom of the crucible body (10) is gradually weakened, the high-temperature area is guided to move upwards, and the temperature gradient stability of the crystal growth area is ensured.

Description

Crystal growth apparatus and method Technical Field The invention belongs to the technical field of semiconductors, and particularly relates to a crystal growth device and a crystal growth method. Background Physical vapor transport (PVT method) is the mainstream method of the growth of 6-8 inch 4H-SiC single crystals. The method adopts the principle of induction heating, and applies alternating current to form a magnetic field through an intermediate frequency power supply, so that a conductor (such as graphite) in a coil generates high-density induction current on the surface layer of the conductor, and the temperature is quickly raised to a high-temperature state. The core components of the PVT method crystal growth comprise graphite (comprising a crucible and components thereof), graphite felt (hard felt or soft felt for heat preservation and constructing temperature gradient), silicon carbide powder for providing sublimate sources, seed crystals and the like. Under the high temperature of at least 2100 ℃ and the lower air pressure environment, the bottom silicon carbide powder can be decomposed and sublimated in a non-stoichiometric ratio to generate SimCn and other gas-phase components, and the gas-phase components are transported from a bottom powder source area to a growth interface due to the existence of an axial temperature gradient and are focused and crystallized. In the crystal growth process, the inside of the bottom silicon carbide powder body is sintered, and a ceramic body containing a large number of pore channels is formed in an initial stage. As the reaction progresses, carbonization occurs in the high temperature region near the crucible wall and bottom of the crucible under the influence of the induction heating "skin effect". As shown in FIG. 1, after graphite is heated by an induction coil, the high temperature zone is mainly concentrated on the surface and bottom of the graphite crucible, and the powder on the bottom and the side close to the crucible wall is carbonized preferentially by combining the action of axial temperature gradient (lower top temperature and higher bottom temperature). The gas phase component generated by carbonization is gathered from the carbonization area from the bottom to the top and from the inside to the center, and as the growth process continues, two characteristic areas shown in figure 2 are formed in the powder, wherein the area (a) is a silicon carbide polycrystalline ceramic body remained in the middle of the crucible, mainly is 6H-SiC, and the particle size is generally larger and belongs to an obvious non-carbonization area. The region is formed by converging SimCn which is formed by powder fully carbonized at high temperature at the bottom and the side wall along a central pore canal, the periphery of a compact ceramic body and the region at the bottom, siC powder particles can be completely decomposed and sublimated, most of solid Si atoms are converted into gaseous Si atoms or SimCn gas phase components, and the material sources can be converged to the surface of seed crystal along the pore canal in the powder under the action of axial temperature gradient, so that raw materials are provided for crystal growth. In an ideal state, in a temperature range of 1200-2300 ℃, all particles in the SiC powder are decomposed and sublimated in a non-stoichiometric ratio, most or all silicon is converted into a gaseous state or other silicon-rich gas phase components, and only solid C particles remain, so that the SiC powder is believed to be completely carbonized. However, in the actual growth process (as shown in fig. 2), only the peripheral side surfaces and the bottom of the ceramic body a can be completely carbonized, and a large number of columnar grains with larger size and regular morphology still exist in the area from the middle to the top of the SiC powder, and the green grains are usually 6H structures and belong to silicon carbide split bodies which are not completely carbonized and are not effectively utilized. Therefore, the practical utilization efficiency of silicon carbide powder is generally not more than 50%. If the secondary recovery of the silicon carbide powder is tried, the graphite powder is mixed, the particle size and the shape of the graphite powder are obviously different from those of the original silicon carbide powder, a large amount of manpower and material resources are required to be consumed in the recovery process, and meanwhile, the purity of the powder is difficult to ensure in the repeated crushing, screening and cleaning processes, so that the feasibility of secondary recovery and utilization is low. For this reason, it is desirable to provide a crystal growth apparatus and method. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a crystal growth device and a crystal growth method, which have simple structure and low manufacturing cost, can remarkably improve the utilization