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CN-121992502-A - Preparation method of wafer-level (100) face-cube silicon carbide single crystal

CN121992502ACN 121992502 ACN121992502 ACN 121992502ACN-121992502-A

Abstract

The invention provides a preparation method of a wafer-level (100) face-cubic silicon carbide single crystal. The preparation method utilizes (100) face 3C-SiC seed crystal, adopts a high-temperature liquid phase method (mainly TSSG method), and obtains the wafer-level (100) face 3C-SiC monocrystal through self-expanding growth under a specified temperature field. In particular, by performing iterative expanding growth as many times as necessary, it is possible to ensure that a wafer-level (100) surface 3C-SiC single crystal of a desired target size is obtained. The preparation method of the invention has the advantages of easy diameter expansion, low growth cost, capability of growing 3C-SiC single crystals with different doping types (100) and suitability for large-scale industrial production, etc.

Inventors

  • CHEN XIAOLONG
  • ZHAO LINLIN
  • LI HUI
  • WANG WENJUN
  • GUO JIANGANG

Assignees

  • 中国科学院物理研究所

Dates

Publication Date
20260508
Application Date
20260309

Claims (10)

  1. 1. A method for preparing a wafer-level (100) face-cubic silicon carbide (3C-SiC) single crystal, comprising the steps of: S1, obtaining (100) surface 3C-SiC seed crystals; S2, placing silicon and a cosolvent into a crucible, fixing the (100) face 3C-SiC seed crystal on a lifting rod above the crucible, and heating the crucible by a heat source under a functional gas atmosphere and set pressure so that the silicon and the cosolvent are completely melted to form a melt, and the melt is in a specified temperature field, wherein the components of the cosolvent and the ratio of the silicon to the cosolvent are selected so that carbon sufficient for growing 3C-SiC single crystals is dissolved in the melt; S3, pushing down the lifting rod to enable the seed crystal to be in contact with the melt, rotating and lifting the seed crystal and the crucible, and dynamically adjusting the relative positions among the heat source, the crucible and the seed crystal, so that the relative position between a crystal growth interface and the melt and the temperature of the crystal growth interface are kept unchanged, and a (100) plane 3C-SiC single crystal is obtained through growth; S4 in the case where the size of the obtained (100) face 3C-SiC single crystal does not reach the target size, cutting the (100) face 3C-SiC single crystal in a direction parallel to the crystal growth face of the (100) face 3C-SiC single crystal and performing grinding, polishing and cleaning to obtain a crystal seed, and And S5, repeating the steps S2 to S4 until the size of the obtained (100) plane 3C-SiC single crystal reaches the target size.
  2. 2. The method of manufacturing according to claim 1, wherein the step of obtaining (100) face 3C-SiC seed crystal comprises: Cutting a (111) face 3C-SiC ingot with a certain thickness and diameter to obtain a (100) face 3C-SiC single crystal substrate, and grinding, polishing and cleaning the single crystal substrate obtained by cutting to obtain the (100) face 3C-SiC seed crystal.
  3. 3. The method of manufacturing according to claim 2, wherein the step of cutting the (111) face 3C-SiC ingot having a certain thickness and diameter to obtain the (100) face 3C-SiC single crystal substrate comprises: Along a 3C-SiC ingot parallel to said (111) plane Cutting at an angle of 54.74 degrees with the (111) plane to obtain the (100) plane 3C-SiC single crystal substrate; The thickness of the (111) face 3C-SiC crystal ingot is more than or equal to 1mm, and the diameter is more than or equal to 1 inch; The thickness of the (100) face 3C-SiC seed crystal is 0.2-1 mm, and the width is more than or equal to 1 mm.
  4. 4. The preparation method according to claim 1, wherein the cosolvent comprises a transition metal or/and a rare earth metal having a carbon-dissolving ability and a melting point lower than a growth temperature of 3C-SiC single crystal; the transition metal is one or more of Fe, co, ni, ti, cu, cr, mn; The rare earth metal is one or more of La, ce, pr, nd, Y; optionally, the cosolvent further comprises Al.
  5. 5. The method of claim 4, wherein the cosolvent comprises Cr; Under the condition that the cosolvent does not contain Al, the atomic mole ratio of Si, cr, transition metals except Cr and rare earth elements is (20-70): (30-60): (0-30): (0-50) and is used for realizing the growth of n-type doped 3C-SiC single crystals; In the case that the cosolvent comprises Al, the atomic mole ratio of Si, cr, transition metals except Cr, rare earth elements and Al is (20-70): (30-60): (0-30): (0-50): (0.5-10) for realizing semi-insulation and growth of p-type doped 3C-SiC single crystal.
  6. 6. The production method according to claim 1, wherein the prescribed temperature field includes a temperature at the crystal growth interface, an axial temperature gradient in which temperature increases progressively from the crystal growth interface toward the bottom of the crucible, and a radial temperature gradient in which temperature increases progressively from a region where a seed crystal is located radially toward the peripheral wall of the crucible; Preferably, the temperature at the crystal growth interface is 1700-2100 ℃; The axial temperature gradient is 0.5-15 ℃ per cm; the radial temperature gradient is 0.5-10 ℃/cm.
  7. 7. The method of manufacturing according to claim 1, wherein the crucible is a graphite crucible; the inner diameter of the graphite crucible is 1.4-30 times of the length of the seed crystal; The wall thickness of the graphite crucible is more than or equal to 10 mm.
  8. 8. The preparation method according to claim 1, wherein the functional gas is one or more selected from Ar, N 2 、Ar/N 2 、He、He/N 2 ; the set air pressure is 0.1-2 atm; Optionally, in the case of growing an n-doped 3C-SiC single crystal, the partial pressure of nitrogen in the functional gas atmosphere is 5-100%; In the case of growing semi-insulating and p-doped 3C-SiC single crystals, the nitrogen partial pressure in the functional gas atmosphere is 0-10%.
  9. 9. The production method according to claim 1, wherein the operation of rotating and pulling the seed crystal and the crucible in step S3 comprises: periodically rotating the seed crystal and the crucible forward and backward and accelerating and decelerating, and slowly pulling the seed crystal and the crucible; Wherein the rotation speed of the seed crystal is +/-0-200 r/min, and the rotation acceleration during acceleration and deceleration is 0.1-200 r/min 2 ; The rotation speed of the crucible is +/-0-50 r/min, and the rotation acceleration during acceleration and deceleration is 0.1-50 r/min 2 ; the pulling speed of the seed crystal and the crucible is 1-3000 mu m/h.
  10. 10. The production method according to claim 1, wherein the operation of fixing the (100) face 3C-SiC seed crystal on the pull rod above the crucible in step S2 comprises: fixing the (100) face 3C-SiC seed crystal on a graphite seed crystal support connected with the lifting rod, wherein the seed crystal is positioned in the middle or at the edge of the graphite seed crystal support; Optionally, the graphite seed holder is a circular seed holder with a flat surface for holding a seed, or The graphite seed crystal support is in a crisscross shape, and a boss for fixing seed crystals is arranged at the tail end of the crisscross.

Description

Preparation method of wafer-level (100) face-cube silicon carbide single crystal Technical Field The invention relates to the technical field of semiconductor materials, in particular to a preparation method of a wafer-level (100) face-cubic silicon carbide single crystal. Background Silicon carbide (SiC) has excellent performances such as wide band gap, high breakdown field strength, high saturated electron drift rate, high thermal conductivity and the like, and has important application in the fields of new energy automobiles, photovoltaics, 5G communication, rail transit, smart grids and the like. Currently, siC-based metal-oxide-semiconductor field effect transistors (MOSFETs) are mainly fabricated on 4H-SiC single crystal substrates. Compared with 4H-SiC, cubic silicon carbide (3C-SiC) has higher carrier mobility, lower resistivity (3C-SiC has resistivity of 0.3 m Ω & cm;4H-SiC has resistivity of 22 m Ω & cm), lower interface state density (Dit, 2 orders of magnitude lower), higher electron affinity (3.7 eV), and higher channel carrier mobility (3C-SiC has channel carrier mobility of 100-370 cm 2/V & s,4H-SiC has channel carrier mobility of 20-180cm 2/V & s). The method for preparing the MOSFET device by using the 3C-SiC can solve the technical bottlenecks of poor reliability and stability, low service life and the like of the SiC-based MOSFET device caused by a gate-oxide interface defect state, and can also reduce energy consumption. 3C-SiC, also known as beta-SiC, the space group is(No. 216) has a Face-centered cubic (Face-Centered Cubic, FCC) structure, and the family of crystal planes mainly includes {100}, {110}, {111}, etc. Physical properties such as atom arrangement mode, surface energy, chemical bond and the like of different crystal face groups are obvious, so that physical, chemical and electrical properties of different crystal face groups are different. The formation energy of the 3C-SiC stacking fault and twin on the (111) crystal plane is much lower than that on the (100) crystal plane. The stacking fault density and twin defect density of the (111) crystal plane are higher than those of the (100) crystal plane. It was found experimentally that by epitaxially growing 3C-SiC, the stacking fault density of the (100) -plane 3C-SiC film was (2.47.+ -. 0.09). Times.10 3 cm-1, the average length was 0.31.+ -. 0.01 mm, and the stacking fault density was (7.16.+ -. 0.04). Times.10 3 cm-1 and the average length was 3.32.+ -. 0.35 mm, which were smaller than those of the (111) -plane 3C-SiC film. In 3C-SiC, the (100) plane has higher electron and hole carrier mobilities than the (111) plane, and the electron mobility of the (100) plane is 460 cm 2/V.s and the electron mobility of the (111) plane is only 200cm 2/V.s when the doping concentration is 5×10 16 cm-3. The activation energy of the (100) plane was higher than that of the (111) plane, and the activation energy of the (100) C plane and Si plane of 3C-SiC and the (111) C plane and Si plane were 30.1 and 35.6, 29.9 and 33.4 kJ/mol, respectively. The high activation energy indicates that the oxidation rate is slow at the typical process temperature, the oxide layer grows more slowly and compactly, the oxidation stability is high, the SiC/SiO 2 interface with more uniform and lower defect state is formed, the flatter surface is formed, and the process requirement is reduced. (100) The surface of the 3C-SiC has fewer dangling bonds, and the dangling bond density of the (100) surface is only 50-60% of that of the (111) surface in the normal case, which is also beneficial to reducing the interface defect state density. It was found that the Dit of the 3C-SiC (100) film/SiO 2 can be as low as 4X 10 10 cm-2·eV-1, two orders of magnitude lower than the Dit of 4H-SiC and 6H-SiC. it can be seen that the (100) plane 3C-SiC has more excellent performance than the (111) plane, contributing to the improvement of the performance of the SiC-based device. The related art reports that a 3C-SiC single crystal with the diameter of 2-4 inches, a single crystal form and the thickness of 4-10 mm is grown for the first time internationally by adopting a liquid phase method, mainly a top seed crystal solution growth method (Top Seeded Solution Growth, TSSG for short), and the growth surface is a (111) surface. The maximum thickness of the ingot was about 10 mm a, and a large-sized 3C-SiC single crystal substrate with a (100) plane of growth could not be obtained. Therefore, there is a need for a method of growing 3C-SiC single crystals with a large size, high quality, and a (100) plane growth surface, to obtain (100) plane 3C-SiC single crystals, which provides a material basis for high performance devices. Disclosure of Invention In response to the foregoing problems, a method of preparing a wafer-level (100) face-cubic silicon carbide single crystal is provided that overcomes or at least partially solves the problems described above. It is an object of th