Regarding the types of carbon-graphite materials used in graphite products in the semiconductor and photovoltaic industries, industry experts believe they can be divided into three categories, or three stages of development. The first category is graphite products produced using compression molding (or extrusion, or vibration molding). These products currently account for a small portion of the carbon-graphite material products used in the semiconductor and photovoltaic industries. The second category is isotropic high-purity graphite products produced using isostatic pressing. These products are currently the most widely used in the semiconductor and photovoltaic industries, accounting for over 80% of the global graphite product volume used in these sectors. The third category is carbon-carbon fiber composites. These are newer materials and products that are replacing graphite materials in these applications.
The use of carbon-carbon fiber composites can be considered the third stage in the application of heaters, thermal insulation materials, and other materials in the semiconductor and photovoltaic industries, representing a higher level of technological development. However, this does not mean that currently used isotropic high-purity graphite products will be phased out and completely replaced by carbon-carbon fiber composites. Industry experts believe that neither type of material and product will replace the other in the semiconductor and photovoltaic industries. They predict that the market will develop into a situation where each holds a significant share of the market.
Carbon-carbon composites are carbon fiber-reinforced carbon matrices. They offer outstanding characteristics such as light weight, excellent ablation resistance, thermal shock resistance, high damage tolerance, high-temperature strength, and high designability. Therefore, they are widely used in a wide range of fields, including aerospace, aviation, and atomic energy. Furthermore, composite materials can be tailored to the desired properties and shapes for specific applications by selecting the fiber type, structure, quantity, matrix precursor, and processing conditions. Consequently, their applications are expanding and gaining increasing attention. Carbon-carbon composites are much stronger than graphite and offer excellent dimensional stability, impact resistance, and thermal shock resistance, with overall mechanical properties surpassing those of graphite. Through purification, the metal impurity content of these materials can be controlled to below 5 ppm.
Carbon-carbon composite thermal field products used in the semiconductor and photovoltaic industries offer the following significant advantages over traditional graphite products:
① They significantly extend product lifespan and reduce component replacement times, thereby improving equipment utilization and reducing maintenance costs.
② Compared to traditional graphite products, they can be made thinner, allowing existing equipment to produce longer and larger diameter products, saving significant investment in new equipment and ensuring a more uniform temperature field.
③ Due to their excellent thermal shock resistance, they are less susceptible to cracking under repeated high-temperature thermal vibration conditions, thus preventing temperature field fluctuations.
④ Traditional graphite thermal field products are difficult to form when pulling large-diameter products. However, due to the excellent performance of carbon-carbon composite materials, carbon-carbon composite thermal field products are currently being widely used in large-diameter pulling processes abroad.
⑤ Using carbon-carbon composite materials as thermal insulation (heat shields) in Czochralski single crystal pulling furnaces can achieve significant energy savings compared to graphite materials due to their excellent thermal insulation performance (some research results suggest a 20% energy saving).