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CN-122013322-A - Silicon carbide crystal and liquid phase growth method thereof

CN122013322ACN 122013322 ACN122013322 ACN 122013322ACN-122013322-A

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to a silicon carbide crystal and a liquid phase growth method thereof. Compared with the prior art, the liquid phase growth method provided by the invention has the advantages that the seed crystal support with the diameter smaller than that of the seed crystal is adopted, and meanwhile, the temperature and the pressure are raised and reduced after the crystal growth is finished, so that the volatilization of metal on the surface of the crystal and the side surface of the seed crystal support is promoted, and the cracks of the surface metal caused by different thermal expansion coefficients with silicon carbide in the cooling process are reduced.

Inventors

  • LI YUXIN
  • GUO YU
  • LIU CHUNJUN
  • PENG TONGHUA
  • YANG JIAN

Assignees

  • 北京天科合达半导体股份有限公司
  • 江苏天科合达半导体有限公司

Dates

Publication Date
20260512
Application Date
20251202

Claims (10)

  1. 1. A liquid phase growth method of silicon carbide crystal, comprising the steps of: S1) preparing raw materials, namely placing a crystal growth raw material into a crucible, bonding seed crystals on a seed crystal support, wherein the diameter of the seed crystals is larger than that of the seed crystal support; S2) melting and preheating the material in a protective atmosphere to melt the crystal growth raw material to form a crystal growth solution, and preheating the seed crystal on the liquid level of the crystal growth solution; S3) seed crystal remelting, namely after preheating is finished, the seed crystal is lowered to the position below the liquid level to carry out seed crystal remelting; S4) crystal growth, namely after the back melting of the seed crystal is finished, lifting the seed crystal to 1-2 mm above the liquid level, rotating the seed crystal and the crucible to perform crystal growth, and simultaneously lifting the seed crystal and the crucible in the process of crystal growth; S5) high-temperature volatilization, namely after growth is finished, reducing the rotation rate of the seed crystal, separating the liquid level of the seed crystal and the liquid level of the crystal growth solution, and then heating and reducing the pressure to volatilize; S6) cooling, namely cooling after the volatilizing treatment is finished, and obtaining the silicon carbide crystal.
  2. 2. The liquid phase growth method according to claim 1, wherein the crystal growth raw material comprises Si x Cr y Al z M a , wherein x, y, z and a are molar concentrations of elements in the crystal growth raw material, x is 30% -70%, y is 20% -60%, z is 1% -10%, a is 0% -5%, and M is a transition metal element and/or a rare earth element.
  3. 3. The liquid phase growth method according to claim 1, wherein the difference between the diameter of the seed crystal and the diameter of the seed crystal holder is 2-10 mm.
  4. 4. The liquid phase growth method according to claim 1, wherein in the step S2), the liquid phase is heated under the pressure of 10-90 kPa, the distance between the seed crystal and the liquid surface is 20-50 mm during preheating, and the preheating time is 40 min-2 h.
  5. 5. The liquid phase growth method according to claim 1, wherein the seed crystal is preheated on the liquid surface of the growing solution after heating to 1700 ℃ to 1900 ℃ in the step S2).
  6. 6. The liquid phase growth method according to claim 1, wherein the seed crystal descending speed in the step S3) is 30-600 μm/h, the distance between the seed crystal and the liquid surface during seed crystal remelting is 0-10 mm, and the seed crystal remelting time is 40 min-2 h.
  7. 7. The liquid phase growth method according to claim 1, wherein the rotation rate of the seed crystal in the step S4) is 50 to 200 rpm, the rotation rate of the crucible is 5 to 100 rpm, the pulling rate of the seed crystal is 5 to 100 μm/h, and the pulling rate of the crucible is 2 to 70 μm/h.
  8. 8. The liquid phase growth method according to claim 1, wherein the rotation rate of the seed crystal is 5-20 rpm when separating the seed crystal from the liquid level of the growing solution in the step S5); Separating the liquid level of the seed crystal from the liquid level of the crystal growth solution by pulling the seed crystal or descending the crucible, wherein the speed of pulling the seed crystal is 1500-5000 mu m/h, and the speed of descending the crucible is 1500-5000 mu m/h; separating the seed crystal from the liquid level of the crystal growth solution to a distance of 20-50 mm; the rotation speed of the seed crystal is 50-200rpm during the volatilization treatment.
  9. 9. The liquid phase growth method according to claim 1, wherein the temperature of the volatilization treatment is 5 ℃ to 50 ℃ higher than the temperature of crystal growth, the pressure of the volatilization treatment is 6 kPa to 40 kPa, and the time of the volatilization treatment is 1 h to 4 h.
  10. 10. A silicon carbide crystal grown by the liquid phase growth method according to any one of claims 1 to 9.

Description

Silicon carbide crystal and liquid phase growth method thereof Technical Field The invention belongs to the technical field of semiconductors, and particularly relates to a silicon carbide crystal and a liquid phase growth method thereof. Background Silicon carbide (SiC) is a representative third-generation wide-bandgap semiconductor material, and has wide application prospects in the fields of new energy automobiles, energy storage and the like. The existing silicon carbide liquid phase crystal growth process generally uses a solvent system of Si xCryAlz, when the growth is finished, the seed crystal is pulled to be separated from the surface of the melt, one or a plurality of liquid drops remain on the surface of the crystal when the seed crystal is separated from the melt, and in the cooling process of the crystal, because the difference of the thermal expansion coefficients of the metal liquid drops and the silicon carbide is larger, larger stress is easy to generate, and dislocation and even crack can be caused. Although seed crystal remelting can eliminate surface pollution and damage before crystal growth begins, in the process, melt can form edge polycrystal on the side face of a seed crystal holder, and edge stress is larger in the cooling process, so that cracks are easily formed at the edge. Disclosure of Invention In view of the above, the present invention provides a silicon carbide crystal and a liquid phase growth method thereof, which can reduce surface droplets and edge polycrystal of the silicon carbide crystal. The invention provides a liquid phase growth method of silicon carbide crystals, which comprises the following steps: S1) preparing raw materials, namely placing a crystal growth raw material into a crucible, bonding seed crystals on a seed crystal support, wherein the diameter of the seed crystals is larger than that of the seed crystal support; S2) melting and preheating the material in a protective atmosphere to melt the crystal growth raw material to form a crystal growth solution, and preheating the seed crystal on the liquid level of the crystal growth solution; S3) seed crystal remelting, namely after preheating is finished, the seed crystal is lowered to the position below the liquid level to carry out seed crystal remelting; S4) crystal growth, namely after the back melting of the seed crystal is finished, lifting the seed crystal to 1-2 mm above the liquid level, rotating the seed crystal and the crucible to perform crystal growth, and simultaneously lifting the seed crystal and the crucible in the process of crystal growth; S5) high-temperature volatilization, namely after growth is finished, reducing the rotation rate of the seed crystal, separating the liquid level of the seed crystal and the liquid level of the crystal growth solution, and then heating and reducing the pressure to volatilize; S6) cooling, namely cooling after the volatilizing treatment is finished, and obtaining the silicon carbide crystal. Preferably, the crystal growth raw material comprises Si xCryAlzMa, wherein x, y, z and a are molar concentrations of elements in the crystal growth raw material, x is 30% -70%, y is 20% -60%, z is 1% -10%, a is 0% -5%, and M is a transition metal element and/or a rare earth element. Preferably, the difference between the diameter of the seed crystal and the diameter of the seed crystal holder is 2-10 mm. Preferably, in the step S2), heating is performed under the condition of the pressure of 10-90 kPa, the distance between the seed crystal and the liquid level is 20-50 mm during preheating, and the preheating time is 40 min-2 h. Preferably, after heating to 1700 ℃ to 1900 ℃ in the step S2), the seed crystal is preheated on the liquid surface of the crystal growth solution. Preferably, the seed crystal descending speed in the step S3) is 30-600 mu m/h, the distance between the seed crystal and the liquid level during seed crystal remelting is 0-10 mm, and the seed crystal remelting time is 40 min-2 h. Preferably, in the step S4), the rotation speed of the seed crystal is 50-200 rpm, the rotation speed of the crucible is 5-100 rpm, the pulling speed of the seed crystal is 5-100 μm/h, and the pulling speed of the crucible is 2-70 μm/h. Preferably, in the step S5), the rotation speed of the seed crystal is 5-20 rpm when the seed crystal is separated from the liquid level of the crystal growth solution; Separating the liquid level of the seed crystal from the liquid level of the crystal growth solution by pulling the seed crystal or descending the crucible, wherein the speed of pulling the seed crystal is 1500-5000 mu m/h, and the speed of descending the crucible is 1500-5000 mu m/h; separating the seed crystal from the liquid level of the crystal growth solution to a distance of 20-50 mm; the rotation speed of the seed crystal is 50-200rpm during the volatilization treatment. Preferably, the temperature of the volatilization treatment is 5-50 ℃ higher than the tempera