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Morgan Technical Ceramics (MTC) recently introduced its chemical vapor deposition silicon carbide (CVD SiC) wafer carriers for high-temperature metal organic chemical vapor deposition (MOCVD) processing. The pure CVD SiC wafer carriers significantly increase the yield for manufacturers of high-brightness light-emitting diodes (LEDs) using gallium nitride (GaN) deposition.
The CVD SiC is 99.999+% pure and exhibits high thermal conductivity and thermal shock resistance. It is a solid monolithic material that achieves theoretical density, generating minimal particulates and exhibiting very high corrosion and erosion resistance. The material can vary opacity and electrical conductivity without the introduction of metallic impurities. The wafer carriers are typically about 17 in. in diameter, holding up to 40 2-4 in. wafers.
MTC’s pure CVD SiC wafer carriers significantly outperform traditional GaN wafer carriers, which are made of graphite and then coated with a layer of CVD SiC. These coated graphite-based carriers cannot stand up to the high temperatures (1100-1200°C) required in GaN deposition for today’s high-brightness blue and white LEDs. The high temperatures cause the coating to develop tiny pinholes through which process chemicals can attack the underlying graphite. Graphite particles can then flake off and contaminate the GaN. A typical coated graphite wafer carrier may have to be replaced as often as monthly, depending on usage conditions.
The pure CVD SiC wafer carriers transmit heat efficiently, with a very high thermal conductivity. For example, CVD SiC has a thermal conductivity of 250-300 watts per meter K (W m-1 K-1). By comparison, sintered SiC’s thermal conductivity is about 100-140 W m-1 K-1, and pure graphite is only about 85 W m-1 K-1. CVD SiC’s higher thermal conductivity results in a uniform temperature across the wafer’s entire diameter, improving the GaN deposition process and significantly increasing the yield of the target wavelength of LEDs compared to coated graphite wafer carriers.
In addition to the increased LED yields with the use of the pure CVD SiC wafer carriers, the pure monolithic SiC is very long-lived; resists warpage; and only needs to be replaced when the carrier is broken, chipped or damaged due to handling. These benefits can result in real cost savings for semiconductor manufacturers.
For more information, visit www.morgantechnicalceramics.com.