Novel aluminum nitride self-seeding nucleation growth method

Abstract

The invention discloses a novel aluminum nitride self-seeding nucleation growth method. The method includes steps of 1), using a protecting layer to isolate a material source from a crystal growth point during the early heating process of the aluminum nitride self-seeding nucleation growth, wherein the protecting layer is inserted between a seed crystal cover and the material source; 2), slowly heating from 1850-2150 DEG C to 2150-2200 DEG C, which is the aluminum nitride self-seeding nucleation window temperature, at the heating rate of 40 DEG C / h; in the heating process, keeping the pressureat 150KPa; 3), keeping the temperature at 2150-2200 DEG C and lowering the pressure to 80000-90000Pa to allow aluminum nitride to start nucleation growth, and maintaining the growth time for 30 hours; 4), lowering the temperature from 2150-2200 DEG C to 1500 DEG C within one hour; meanwhile, charging argon into the furnace. The method has the advantages that the method is simple to implement; byinserting a wafer protecting layer between the material source and the seed crystal cover, excessive nucleation points caused by excessively early nucleation of aluminum nitride on the tantalum carbide seed crystal cover before the optimal C-axis (0001) crystal growth temperature field is reached can be avoided; the method is low in cost, high in repeatability and obvious in effect.

Description

technical field [0001] The invention relates to the field of aluminum nitride self-nucleation growth, in particular to a novel aluminum nitride self-nucleation growth method. Background technique [0002] AlN crystal is an important wide bandgap (6.2eV) semiconductor material with high thermal conductivity (3.2W.cm -1 K -1 ), high resistivity and high surface acoustic velocity (5600-6000m / s) and other excellent physical properties, it is widely used in lasers, high-power electronic devices, optoelectronic devices and surface acoustic wave devices. At present, the physical vapor transport method (PVT) is recognized as an effective way to prepare large-sized aluminum nitride single crystals, and the method of preparing large single crystals is easier to use than self-nucleation growth by using a seed crystal bottom. [0003] The method of growing AlN crystals on heterogeneous substrates by the sublimation method can grow large-sized AlN crystals using large-diameter heteroge...

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Problems solved by technology

[0003] The method of growing AlN crystals on heterogeneous substrates by the sublimation method can grow large-sized AlN crystals using large-diameter heterogeneous substrates, but due to the lattice mismatch and thermal mismatch between the substrate seeds; in addition , the anisotropy of the thermal expansion coefficient of the c-axis and a-axis of the aluminum nitride crystal is relatively large, resulting in large internal stress and severe cracking during the crystal growth process

[0004] In order to obtain high-quality, low-stress aluminum nitride single crystal, this patent adopts the method of self-nucleation for growth. However, the growth method of PVT free nucleation and growth of aluminum nitride without substrate has the problem of difficult diameter expansion, and the crystal Too many nucleation points cause competitive growth, which makes it difficult to expand the size of single crystal particles

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