Silicon Carbide(SiC) Crystal Growth Furnace

Crystal growth is the core link in the production of Silicon Carbide substrates, and the core equipment is the crystal growth furnace. Similar to traditional crystalline silicon-grade crystal growth furnaces, the furnace structure is not very complex and mainly consists of a furnace body, a heating system, a coil transmission mechanism, a vacuum acquisition and measurement system, a gas path system, a cooling system, a control system, etc., among which Thermal field and process conditions determine the quality, size, conductive properties and other key indicators of Silicon Carbide crystals.

The temperature during the growth of silicon carbide crystals is very high and cannot be monitored, so the main difficulty lies in the process itself.

(1) Thermal field control is difficult: The monitoring of closed high-temperature cavities is difficult and uncontrollable. Different from traditional silicon-based solution Czochralski crystal growth equipment, which has a high degree of automation and the crystal growth process can be observed and controlled, silicon carbide crystals grow in a closed space at a high temperature of over 2,000°C, and the growth temperature needs to be precisely controlled during production. , temperature control is difficult;

(2) It is difficult to control the crystal form: defects such as microtubules, polytype inclusions, and dislocations are prone to occur during the growth process, and they interact and evolve with each other. Micropipes (MP) are penetrating defects with sizes ranging from a few microns to tens of microns and are killer defects of devices; silicon carbide single crystals include more than 200 different crystal forms, but only a few crystal structures (4H type) are It is a semiconductor material required for production. During the growth process, crystalline transformation is prone to occur, causing multi-type inclusion defects. Therefore, it is necessary to accurately control parameters such as silicon-carbon ratio, growth temperature gradient, crystal growth rate, and air flow pressure. In addition, silicon carbide single crystal growth There is a temperature gradient in the thermal field, which leads to the existence of defects such as native internal stress and resulting dislocations (basal plane dislocation BPD, screw dislocation TSD, edge dislocation TED) during the crystal growth process, thus affecting subsequent epitaxy and devices. quality and performance.

(3) Doping control is difficult: the introduction of external impurities must be strictly controlled to obtain directionally doped conductive crystals;

(4) Slow growth rate: The crystal growth rate of silicon carbide is very slow. It only takes 3 days for traditional silicon material to grow into a crystal rod, while it takes 7 days for a silicon carbide crystal rod. This results in a natural decrease in the production efficiency of silicon carbide. Lower, output is very limited.

On the other hand, the parameters of silicon carbide epitaxial growth are extremely demanding, including the airtightness of the equipment, the pressure stability of the reaction chamber, the precise control of the gas introduction time, the accuracy of the gas ratio, and the strict management of the deposition temperature. Especially as the voltage level of devices increases, the difficulty of controlling the core parameters of epitaxial wafers increases significantly.

In addition, as the thickness of the epitaxial layer increases, how to control the uniformity of resistivity and reduce the defect density while ensuring the thickness has become another major challenge. In electrified control systems, it is necessary to integrate high-precision sensors and actuators to ensure that various parameters can be accurately and stably regulated. At the same time, the optimization of the control algorithm is also crucial. It needs to be able to adjust the control strategy based on feedback signals in real time to adapt to various changes in the silicon carbide epitaxial growth process.

Semicorex offers high-quality components for SiC crystal growth. If you have any inquiries or need additional details, please don't hesitate to get in touch with us.

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