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CN-121976287-A - Silicon melt circulation optimization system and optimization method

CN121976287ACN 121976287 ACN121976287 ACN 121976287ACN-121976287-A

Abstract

The invention relates to a silicon melt circulation optimization system and an optimization method, and belongs to the field of semiconductor material production. The technical scheme is that the silicon melt circulation field optimization system comprises a crucible, wherein a lifting rod is arranged at the center of the top of the crucible, the lower end of the lifting rod stretches into the crucible, the upper end of the lifting rod is connected with a first rotation driving device, the crucible is connected with a second rotation driving device, the rotation axis of the lifting rod and the rotation axis of the crucible are arranged in a collinear manner and all along the vertical direction, the system further comprises a magnetic field generating device, the magnetic field generating device can generate a magnetic field along the horizontal direction, and the crucible is positioned in the magnetic field generating device and is positioned in the magnetic field generated by the magnetic field generating device. The double-rotation driving device is matched with the collinear vertical axis design, so that the rotation speed difference can be accurately formed, stable forced circulation is constructed, disordered natural convection can be effectively restrained by matching with a horizontal magnetic field, crystal defects are reduced, and the purity and structural integrity of silicon crystals are improved.

Inventors

  • SONG DEPENG
  • ZHANG SHANGHAO

Assignees

  • 山东力冠微电子装备有限公司

Dates

Publication Date
20260505
Application Date
20260114

Claims (10)

  1. 1. The silicon melt circulation field optimization system comprises a crucible (1) and is characterized in that a lifting rod (2) is arranged at the center of the top of the crucible (1), the lower end of the lifting rod (2) stretches into the crucible (1), a first rotation driving device is connected to the upper end of the lifting rod (2), a second rotation driving device is connected to the crucible (1), the rotation axis of the lifting rod (2) and the rotation axis of the crucible (1) are arranged in a collinear manner and all in the vertical direction, and the silicon melt circulation field optimization system further comprises a magnetic field generating device, wherein the magnetic field generating device can generate a magnetic field in the horizontal direction, and the crucible (1) is located in the magnetic field generating device and is located in the magnetic field generated by the magnetic field generating device.
  2. 2. Silicon melt circulation field optimization system according to claim 1, characterized in that the magnetic field generating device comprises two electromagnets (3), the electromagnets (3) are of a plate type structure, the plate surfaces of the electromagnets (3) are vertical surfaces, the two electromagnets (3) are oppositely arranged in parallel, and the polarities of the opposite surfaces of the two electromagnets (3) are opposite.
  3. 3. Silicon melt circulation field optimization system according to claim 2, characterized in that the area of the electromagnet (3) is larger than and completely covers the axial cross section of the inner cavity of the crucible (1).
  4. 4. Silicon melt circulation field optimization system according to claim 1, characterized in that the second rotation driving device comprises a second gear motor (9), a second driving pulley (10) is arranged on an output shaft of the second gear motor (9), a connecting shaft (12) is arranged at the bottom center of the crucible (1), a second driven pulley (11) is arranged at the lower end of the connecting shaft (12), and a second transmission belt (13) is arranged on the second driving pulley (10) and the second driven pulley (11) in a surrounding mode.
  5. 5. Silicon melt circulation field optimization system according to claim 1, characterized in that the first rotation driving means comprises a first gear motor (5), a first driving pulley (6) is mounted on an output shaft of the first gear motor (5), a first driven pulley (7) is connected to the periphery of the lifting rod (2) through a spline, the lifting rod (2) can move up and down relative to the first driven pulley (7), and a first driving belt (8) is arranged on the first driving pulley (6) and the first driven pulley (7) in a surrounding mode.
  6. 6. A silicon melt circulation field optimization system according to any one of claims 1-3, characterized in that the magnetic field generating means further comprises an electromagnet base (4), both electromagnets (3) being mounted on the electromagnet base (4), the crucible (1) being located above the electromagnet base (4), the electromagnet base (4) being connected with third rotary drive means.
  7. 7. Silicon melt circulation field optimization system according to claim 6, characterized in that the electromagnet base (4) is annular, the third rotary driving device comprises a third gear motor (14), a third driving pulley (15) is mounted on an output shaft of the third gear motor (14), a belt groove (17) is formed in an outer circular surface of the electromagnet base (4), a third driving belt (16) is mounted on the electromagnet base (4) and the third driving pulley (15) in a surrounding mode, and the third driving belt (16) is located in the belt groove (17).
  8. 8. A method for optimizing a silicon melt circulation field, comprising the steps of: The method comprises the steps that a first rotary driving device is used for driving a lifting rod (2) to rotate around the vertical axis of the lifting rod, and a second rotary driving device is used for driving a crucible (1) containing silicon melt to rotate around the vertical axis of the crucible, the lifting rod (2) is collinear with the rotation axis of the crucible (1), a rotating speed difference is formed between the lifting rod (2) and the crucible (1), and stable forced circulation is formed in the silicon melt; The magnetic field generating device applies a horizontal magnetic field outside the crucible to inhibit disordered natural convection in the silicon melt.
  9. 9. A method of optimizing the circulating field of a silicon melt according to claim 8, characterized in that the third rotary drive means drive the electromagnet base (4) carrying the electromagnet (3) in rotation, dynamically changing the direction of the applied horizontal magnetic field in the horizontal plane.
  10. 10. Silicon melt circulation field optimization method according to claim 8 or 9, characterized in that the operating parameters of the lifting rod (2), crucible (1) and magnetic field generating device are adjusted cooperatively according to the different phases of crystal growth: in the seeding stage, a lifting rod and a seed crystal are driven to rotate at a low speed of 5-8 rpm, a circumferential thermal field of the lifting rod and the seed crystal is homogenized, a crucible is kept static or rotates at a low speed and the same direction of 0-2rpm, a weak magnetic field below 0.1T is applied by a magnetic field generating device, and an electromagnet base slowly rotates at a speed of 0.1-0.5 rpm; In the equal-diameter growth stage, the lifting rod and the crystal rotate at a process speed of 12-15 rpm, the crucible reversely rotates at a low speed of 0.5-1rpm to establish forced circulation, and the magnetic field generating device applies a magnetic field of 0.3-0.5T and rotates at a constant speed of 0.5-2 rpm; And in the ending stage, firstly, gradually reducing the rotation speed of the magnetic field to zero, then, synchronously and slowly reducing the magnetic field intensity to be completely closed, and synchronously and gradually reducing the rotation speeds of the crystal and the crucible along with the release of the intervention of the magnetic field.

Description

Silicon melt circulation optimization system and optimization method Technical Field The invention relates to the field of semiconductor material production, in particular to a silicon melt circulation optimization system and an optimization method. Background Silicon semiconductors are used as a foundation of the modern information technology industry and play an irreplaceable role in the fields of integrated circuits, photovoltaic power generation, power devices and the like. With the rapid development of strategic emerging industries such as 5G communication, artificial intelligence, new energy automobiles and the like, the quality requirements on silicon wafers are increasingly stringent, and particularly, higher standards are put forward in terms of large size, high purity, low defect density and the like. Currently, the Czochralski method has become the dominant technology for producing monocrystalline silicon because of its mature process system and good cost control capability, and occupies about 90% of the market share worldwide. In the crystal growth process of the Czochralski method, a polycrystalline silicon raw material is melted in a quartz crucible to form a silicon melt, and silicon atoms are orderly arranged along a specific crystal direction and gradually grown into a single crystal silicon ingot by guiding a seed crystal and controlling thermal field conditions. The control accuracy of this process directly determines the quality of the final crystal. However, due to the temperature gradient and density differences existing in the crucible, and the rotation of the crucible, the silicon melt is not in a steady state but a random circulation is generated at random local positions. The random shearing force generated by the disordered circulation can directly act on the solid-liquid interface to interfere the ordered arrangement of atoms at the growth front of the crystal. Such disturbance may cause the lattice arrangement to be out of order, inducing the generation of crystal defects such as dislocation and stacking fault. Meanwhile, disorder circulation causes severe fluctuation of the temperature of the melt, and the stability of a solid-liquid interface thermal field is destroyed. Such thermal oscillations can cause periodic changes in growth rate, which in turn can cause fluctuations in the solute segregation coefficient. It directly represents an axial oscillation of the dopant concentration in the crystal, forming alternately dark and light growth fringes on the cross section of the crystal. These fringes are not only impurity-rich regions, but also stress-concentrated regions, which significantly reduce the mechanical strength and chemical stability of the crystal. Disclosure of Invention The invention provides a silicon melt circulation optimization system aiming at the problem that the production effect is affected by disordered circulation in a silicon melt when silicon crystals are produced by a Czochralski method. In order to solve the problems, the technical scheme includes that the silicon melt circulation field optimization system comprises a crucible, wherein a lifting rod is arranged at the center of the top of the crucible, the lower end of the lifting rod stretches into the crucible, the upper end of the lifting rod is connected with a first rotation driving device, the crucible is connected with a second rotation driving device, the rotation axes of the lifting rod and the crucible are arranged in a collinear manner and all along the vertical direction, and the system further comprises a magnetic field generating device, wherein the magnetic field generating device can generate a magnetic field along the horizontal direction, and the crucible is positioned in the magnetic field generating device and positioned in the magnetic field generated by the magnetic field generating device. Meanwhile, the application of the horizontal magnetic field can form uniform constraint on the silicon melt by utilizing electromagnetic force, strongly inhibit disordered natural convection caused by temperature gradient and density difference, reduce disturbance of random shearing force on a solid-liquid interface, reduce generation probability of crystal defects such as dislocation and stacking fault, remarkably improve purity, structural integrity and mechanical strength of silicon crystals, and provide stable and reliable technical support for production of large-size and high-specification silicon wafers. As a preferable implementation scheme of the silicon melt circulation field optimization system, the magnetic field generation device comprises two electromagnets, the electromagnets are of a plate type structure, the plate surfaces of the electromagnets are vertical surfaces, the two electromagnets are oppositely arranged in parallel, and the polarities of the opposite surfaces of the two electromagnets are opposite. The electromagnet of the plate structure is matched with the vertical