Different semiconductor device preparation has different morphological requirements for semiconductor materials, including single crystal wafers, milled wafers, polished wafers, thin films, etc. Different shapes of semiconductor materials require different processing processes. Semiconductor material bulk material preparation process includes purification, single crystal preparation and thin film epitaxial growth.
Each semiconductor material has to be purified from the raw material, and the required purity is 6 "9" to 11 "9" or more. There are two types of purification methods. One is purification without changing the chemical composition of the material, called physical purification; the other is purification by converting the elements into compounds and then converting the purified compounds into elements, called chemical purification. The physical purification methods include vacuum evaporation, regional refining, and crystal pulling purification, etc. The regional refining is commonly used. Electrolysis, complexation, extraction, and distillation are the main methods of chemical purification. Because each method has certain limitations, a process flow combining several types of purification methods is often used to obtain qualified materials.
The vast majority of semiconductor devices are fabricated on single crystal wafers or epitaxial wafers with single crystal wafers as substrates. Bulk semiconductor single crystals are made by melt growth methods. The straight pulling method is widely used, with 80% of silicon single crystals, most germanium single crystals and zirconium antimonide single crystals being produced by this method, where the large diameter of silicon single crystals is 300 mm. the straight pulling method, where a magnetic field is introduced into the melt, is called magnetron pulling, and this method has produced highly homogeneous silicon single crystals. The addition of a liquid covering agent to the surface of the crucible melt, called the liquid-sealed direct pulling method, is used to decompose single crystals with large pressure, such as gallium arsenide, gallium phosphide, and indium phosphide. High purity silicon single crystals are grown by this method without touching the vessel. The horizontal zone melting method is used to produce germanium single crystals. The standard directional crystallization method is mainly used to prepare gallium arsenide single crystals, while the vertical directional crystallization method gallium is mainly used for vertical directional crystallization. By crystal orientation, tumbling, as a reference surface, slicing, grinding, chamfering, polishing, etching, cleaning, inspection, packaging and other processes in whole or in part.
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