Growth method of low-stress aluminum nitride crystal

Abstract

The invention discloses a growth method of a low-stress aluminum nitride crystal. According to the growth method, rapid two-dimensional mode growth of an AIN (Aluminum Nitride) crystal is achieved ina temperature and pressure variable mode, the stress of a single aluminum nitride crystal is reduced, and the single aluminum nitride crystal which has no crack on a growth surface and has naturally grown steps is grown. According to the growth method, a temperature control process and a mode that the temperate and the pressure of a specific temperature interval are varied in the growth process are adopted, the atom nucleation rate is reduced because of high pressure and low temperatures at a former stage, the primary nucleation tidiness is improved, and substrate decomposition failure is inhibited; at a middle growth stage, the pressure is reduced, so that the growth velocity is increased, and substrate decomposition is retarded; at a later stage, the temperature and the pressure are increased, nitrogen source supply is increased, a three-dimension island growth mode is avoided, the phenomena of non-uniform deposition and relatively large stress are reduced, secondary temperature increasing is implemented after cooling, the stress inside the crystal is reduced, cracks on the surface of the crystal is healed, a silicon carbide substrate is decomposed, and thus a self-striped high-quality single aluminum nitride crystal is grown.

Description

technical field [0001] The invention relates to the field of aluminum nitride single crystal preparation, in particular to a method for growing a low-stress aluminum nitride crystal. 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, using large-diameter heterogeneous substrates can grow...

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Problems solved by technology

[0005] Aiming at the problems existing in the prior art, the object of the present invention is to provide a method for growing low-stress aluminum nitride crystals, which adopts a series of variable temperature and variable pressure growth processes, using different pressures and temperatures in the early, middle and late stages, and the last two The second temperature rise overcomes the problems of substrate decomposition during the growth of heterogeneous substrates, poor crystal quality at the interface of the substrate deposition layer, large internal stress of the crystal, and many cracks

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