Conductive Coated Graphite Heaters

The conductive coated graphite heater is a new product designed for high temperature semiconductor processing and other vacuum thermal systems. It employs the good thermal stability of high purity graphite and the excellent surface characteristics of a silicon carbide (SiC) coating. Conductive coated graphite heater is further differentiated by its inclusion of a nitrogen-doped SiC layer that offers greatly improved surface conductivity, making it especially well-suited for applications that need controlled and even heating with great electrical performance.

The heater is constructed with a high-strength graphite substrate, which acts as the core structural and thermal conductor. The graphite was chosen, specifically given its high levels of thermal conductivity, low thermal expansion coefficient and resilience to thermal shock. These characteristics make graphite a suitable base material in high temperature process applications where there may be rapid heating and cooling cycles. However, pristine graphite itself is chemically reactive in certain atmospheres and can experience surface damage or degradation, particle emission, or carryover during extended use, especially in semiconductor cleanroom environments.

To overcome these limitations, the graphite part is coated with a thick, high-purity SiC layer. The SiC coating serves multiple functions: it provides a level of protection against oxidation and chemical corrosion, it provides a very hard, wear resistant surface, and it ensures compatibility with vacuum and cleanroom standards. SiC has a reputation for extreme hardness, high thermal conductivity, and chemical inertness; for this reason it is an excellent coating material for high-performance thermal components.

The unique innovation of this product is the nitrogen doping of the SiC coating. During the chemical vapor deposition (CVD) process, nitrogen atoms are embedded into the SiC lattice, producing free carriers, which can dramatically decrease its surface resistivity, and therefore create a conductive surface layer and allow current to pass directly, rather than using an access point, through the SiC coating, thus allowing the entire graphite component to act as a resistive heating element.

Classic SiC coatings are insulative, which really limits them in the scope of active electrical applications. Conversely, the nitrogen-doped SiC layer on the heater has an extremely low surface resistance while still maintaining all the mechanical and chemical benefits of classic SiC. The conductive layer provides very good current uniformity and minimizes power loss while improving thermal distribution on the heater surface. It is particularly ideal for precision heating applications under conditions often associated with epitaxial reactors, diffusion furnaces, and rapid thermal processing (RTP) equipment.

The heater geometry, typically spiral or serpentine as shown in the image, is designed and optimized with the intent of producing uniform thermal output energy and uniform electrical loading. With the integrated design of the graphite and conductive SiC coating, electrical contacts can be made directly onto the coated surface which eliminates the need for any additional electrodes or metal connection. This reduces contamination risks and results in a simpler assembly. Consequently, the overall efficiency is improved.

Key benefits of the conductive SiC-coated graphite heater include:

Excellent electrical conductivity due to nitrogen doping, enabling direct current flow and efficient resistive heating.

Superior thermal uniformity with precise temperature control over the entire surface area.

High chemical resistance, particularly in corrosive environments such as hydrogen, ammonia, or halogen-rich atmospheres.

Minimal particle generation, meeting the stringent purity requirements of semiconductor fabrication.

Extended service life, owing to the mechanical durability and thermal shock resistance of both the graphite core and SiC coating.

The applications for this heater extend across a number of advanced technology industries. The heater will find a place in semiconductor manufacturing processes like chemical vapor deposition (CVD), molecular beam epitaxy (MBE), and wafer annealing, where precise temperature control and purity of materials are critical. The SiC-coated graphite heater can also be used in photovoltaic production, sintering of advanced ceramics, and in other thermal processes where higher performance, durability, and robust heaters are required.

In summary, the conductive SiC-coated graphite heater is an impressive advancement in the development of thermal components. By using a nitrogen-doped SiC coating, we have developed an effective thermal product, which successfully combines the chemical stability of the SiC coating with electrical conductivity. Thus, producing a thermal process that is more efficient, cleaner, and more reliable for the most demanding industrial applications. The semiconductor and materials industries face continued change and hybrid materials of this kind will become increasingly important in enabling future more advanced technologies for manufacturing.

Semicorex offers high-quality graphite heaters with coating products. If you have any inquiries or need additional details, please don't hesitate to get in touch with us.

Contact phone # +86-13567891907

Email: sales@semicorex.com