The development of semiconductor and the application of graphite materials in the semiconductor industry are inseparable. In the semiconductor industry, a large number of high purity graphite materials are used in the heating system of the single crystal furnace. In the semiconductor wafer processing (including the zone melting, epitaxy, contour processing, etc.) the graphite materials are the auxiliary tool, parts, in the production of polysilicon materials used in the semiconductor silicon wafer as an auxiliary tool, parts. Graphite products for electronic engineering, first of all, to achieve the application in the semiconductor industry. Entering the 21st century, photovoltaic industry has been rapid development, the polysilicon ingot material used in solar battery appeared rapid increase on the yield and market , it also provides a broad prospects of development of new markets for graphite products in the field of photovoltaic industry .
The graphite component used in the direct pulling single crystal furnace is a kind of consumable parts, which is processed by a variety of high pure graphite. For example the graphite crucible and other graphite components use high purity fine structure graphite; graphite heater use the high pure isotropic graphite; graphite insulation cover and a graphite cover use high pure granular structure of graphite.
In the production of polycrystalline silicon ingot device, a plurality of components need graphite materials. Especially the heating materials used in ingot furnace heater-high purity graphite, and the heat insulation materials- high purity carbon felt insulation materials, they are the important and indispensable supporting material in polycrystalline silicon ingot casting equipment.
Due to the heating temperature of the ingot furnace heater is very high (more than 1600 DEG C), the heating material can’t react with silicon material and can’t pollute the silicon material , it must be used in vacuum and inert atmosphere for a long time. The heater is in accordance with the conditions of use, such as metal tungsten, molybdenum and non - metallic graphite. But the tungsten and molybdenum are expensive and difficult to process, the source of graphite is wide and can be processed into various shapes. In addition, graphite has the characteristics of small thermal inertia, fast heating, high temperature resistance, heat shock resistance, large radiation area, high heating efficiency, and stable performance. Because of this, graphite materials have become the preferred heating material in the ingot furnace heater.
