What are SiC-coated graphite susceptors?

The tray (base) that supports SiC wafers, also known as a "susceptor," is a core component of semiconductor manufacturing equipment. And what exactly is this susceptor that carries the wafers?

In the process of wafer manufacturing, the substrates need to be further built with epitaxial layers for device fabrication. Typical examples include LED emitters, which require GaAs epitaxial layers on top of silicon substrates; on conductive SiC substrates, SiC epitaxial layers are grown for devices like SBDs and MOSFETs, used in high voltage and high current applications; on semi-insulating SiC substrates, GaN epitaxial layers are built to construct devices such as HEMTs, used in RF applications like communications. This process heavily relies on CVD equipment.

In CVD equipment, substrates cannot be directly placed on metal or a simple base for epitaxial deposition, as it involves various influencing factors such as gas flow direction (horizontal, vertical), temperature, pressure, stability, and removal of contaminants. Therefore, a base is needed on which the substrate is placed before using CVD technology to deposit epitaxial layers on the substrate. This base is known as a SiC-coated graphite susceptor (also called a base/tray/carrier).

SiC-coated graphite susceptors are commonly used in metalorganic chemical vapor deposition (MOCVD) equipment to support and heat single crystal substrates. The thermal stability and uniformity of SiC-coated graphite susceptors play a crucial role in determining the quality of epitaxial material growth, making them critical components of MOCVD equipment.

MOCVD technology is currently the mainstream technique for growing GaN thin film epitaxy in blue LED production. It offers advantages such as simple operation, controllable growth rate, and high purity of the produced GaN thin films. The susceptors used for GaN thin film epitaxial growth, as an important component inside the MOCVD equipment reaction chamber, needs to have high temperature resistance, uniform thermal conductivity, good chemical stability, and strong resistance to thermal shock. Graphite materials can meet these requirements.

Graphite susceptors are one of the core components in MOCVD equipment and serve as carriers and heat emitters for substrate wafers, directly influencing the uniformity and purity of thin film materials. Consequently, their quality directly affects the preparation of Epi-Wafers. However, during production, graphite can corrode and degrade due to the presence of corrosive gases and residual metalorganic compounds, significantly reducing the lifespan of graphite susceptors. Additionally, the fallen graphite powder can cause contamination on the chips.

The emergence of coating technology provides a solution to this problem by providing surface powder fixation, enhanced thermal conductivity, and balanced heat distribution. The coating on the surface of graphite susceptors used in the MOCVD equipment environment should possess the following characteristics:

1. The ability to fully enclose the graphite base with good denseness, as the graphite susceptor is susceptible to corrosion in corrosive gas environments.

2. Strong bonding with the graphite susceptor to ensure that the coating does not easily detach after multiple high-temperature and low-temperature cycles.

3. Excellent chemical stability to prevent the coating from becoming ineffective in high-temperature and corrosive atmospheres. SiC possesses advantages such as corrosion resistance, high thermal conductivity, resistance to thermal shock, and high chemical stability, making it ideal for working in GaN epitaxial atmospheres. Furthermore, SiC's thermal expansion coefficient is very close to that of graphite, making it the preferred material for coating the surface of graphite susceptors.

Semicorex fabricates CVD SiC coated graphite susceptors, producing customized SiC parts, such as wafer boats, cantilever paddles, tubes, etc. 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