China has grown ultra thick silicon carbide single crystals with a thickness of up to 100 mm for the first time!
The thickness of silicon carbide single crystals is generally about 15-30 mm. The ZDKC research team has made significant improvements to the growth method of silicon carbide single crystals and finally grown this “large block” silicon carbide single crystal
The benefits of extra thickness
Thanks to its excellent properties such as wide bandgap, high thermal conductivity, high breakdown field strength, high electron saturation drift rate, good chemical and thermal stability
Semiconductor silicon carbide materials can meet the requirements of high efficiency, miniaturization, and lightweighting in power electronic systems;
There are also broad application prospects in fields such as EV, photovoltaic and wind power generation, rail transit, smart grid…
However, such good materials are not cheap, especially the high cost of silicon carbide substrates, which seriously restricts the large-scale promotion and application of semiconductor silicon carbide technology.
To reduce the cost of silicon carbide substrates, the main approach is to start with silicon carbide single crystals. The expensive silicon carbide substrate is obtained by processing silicon carbide single crystals using processes such as cutting, grinding, and polishing.
If thicker silicon carbide single crystals are grown, it can not only reduce the amount of seed crystals, shorten the growth time per unit thickness of crystals, improve production efficiency, but also reduce energy consumption and auxiliary material usage, thereby significantly reducing the cost of silicon carbide substrates.
To significantly increase the thickness of silicon carbide single crystals, it is necessary to solve the problems of temperature gradient and stress control of the crystals. In order to solve the problem, the joint laboratory conducted research on the growth of ultra-thick silicon carbide single crystals using Pulling Physical Vapor Transport (PPVT) method.
By pulling the seed crystal and the already grown crystal, the crystal growth surface is always in a suitable radial temperature gradient, forming a surface morphology that is conducive to reducing crystal stress. Simultaneously maintain a suitable axial temperature gradient between the crystal growth surface and the powder to prevent a significant decrease in crystal growth rate as the crystal thickness increases.
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By using the pull-up physical gas transport method, ZDKC successfully grew silicon carbide single crystals with a diameter of 6 inches (i.e. 150 mm), with a thickness exceeding 100 mm. The results of testing and processing the substrate show that the ultra-thick silicon carbide single crystal has a single 4H crystal structure, good crystal quality, and an average resistivity of no more than 30 m Ω· cm.