Glassy Carbon Coating Felt

Semicorex Glassy Carbon Coating Felt acts as an inner insulation layer in silicon carbide epitaxial reactors. It is a high-performance insulation material designed for advanced thermal environments. This product overcomes typical semiconductor high-temperature manufacturing challenges by offering superior solutions due to its lightweight and excellent thermal insulation properties of graphite felt, coupled with the surface integrity and chemical inertness imparted by a glassy carbon coating.

The base material is a high purity graphite felt chose for its low thermal conductivity high temperature stability and light weight. Normal graphite felt usually has surface fiber shedding and particle generation at elevated temperatures which can contaminate the process environment in sensitive epitaxial systems. To mitigate this issue, the surface of the graphite felt is uniformly coated with a layer of glassy carbon—a dense, non-porous form of carbon known for its chemical inertness, low gas permeability, and exceptional thermal stability.

Glassy carbon is a non-graphitized carbon that combines the properties of glass and ceramics. In contrast to crystalline graphite, it is an amorphous, nearly 100% sp2 hybridized carbon material, which is formed by high-temperature sintering of polymerized organic precursors, such as phenolic resin, furfuryl alcohol resin, etc., in an inert gas atmosphere. Because it is black throughout and has a smooth surface similar to glass, it is called glassy carbon.

Glassy carbon coating can eliminate the generation of furnace particles, provide sealed surface pores, have excellent demolding properties and reduce permeability, making this material very suitable for continuous casting molds and products in the semiconductor industry. This material has a wide range of applications in the semiconductor industry, especially in graphite parts such as single crystal silicon pulling equipment components, epitaxial growth components, continuous casting molds, glass sealing jigs, etc.

Glassy carbon has high temperature resistance up to 3000°C in inert gas or vacuum, and unlike all other ceramic and metallic high temperature materials, the strength of glassy carbon increases with increasing temperature up to 2700K, and it does not become brittle and has extremely high thermal shock resistance, so short heating and cooling times are no problem. In addition, glassy carbon has low mass, low heat absorption and low thermal expansion, so it is suitable for almost all high temperature applications.

The glassy carbon coating plays a crucial role in sealing the surface pores of the graphite felt, significantly reducing the release of particles and carbon dust during operation. This is especially critical in SiC epitaxial growth processes, where even minimal contamination can compromise wafer quality and device performance. By encapsulating the porous structure of the felt with a smooth, hard glassy carbon shell, the coating ensures a clean and stable thermal environment within the reaction chamber.

Key advantages of Glassy Carbon Coating Felt include:

Reduced Particle Shedding: The dense coating effectively locks in loose fibers and particles, preventing contamination of wafers and reactor components.

High Thermal Stability: Both the graphite felt and glassy carbon can withstand temperatures exceeding 2000°C in inert or vacuum atmospheres, making the product ideal for high-temperature SiC processes.

Chemical Inertness: The glassy carbon surface is resistant to most acids and corrosive gases, extending the operational life of the insulation layer under harsh conditions.

Improved Process Consistency: The minimized particle generation contributes to a more stable and repeatable epitaxial growth environment, which is essential for producing high-quality SiC wafers.

Applications of Glassy Carbon Coating Felt extend primarily to SiC epitaxial growth furnaces, where it is used as a thermal insulation layer within the hot zone. The product is typically installed as a lining material in the upper or lower insulation stacks, where it provides both thermal protection and cleanliness assurance.