News

15 September 2009

 

Morgan claims yield improvement with pure CVD SiC carriers

High-purity wafer carriers from component supplier Morgan Technical Ceramics (MTC) will significantly improve the production yield of high-brightness LEDs, claims the company.

Its latest carriers, designed for the high temperatures inside gallium nitride metal-organic chemical vapor deposition (MOCVD) reactors, are based on solid monolithic silicon carbide (SiC) material.

The carrier components are themselves fabricated using a CVD process, which Morgan says delivers SiC material with a purity of at least 99.999%.

The wafer carriers are typically about 17 inches in diameter, and can hold up to 40 wafers measuring between 2 and 4 inches in diameter.

Traditionally, the wafer carriers used in MOCVD reactors have been made from graphite, which is then coated with a layer of CVD SiC. According to Morgan, this can be problematic: “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,” says the firm. While the traditional carriers can develop pinholes, flaking off graphite particles that may contaminate wafers in production, Morgan says that the new monolithic carriers offer better corrosion and erosion resistance.

Another advantage is gained from the better thermal conductivity of the monolithic SiC, it is claimed: “[This] 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.”

A division of the Morgan Crucible Company, MTC has manufacturing sites around the world. The CVD SiC components are fabricated at its US site in Hudson, NH, where it also produces pyrolytic boron nitride.

Search: HB-LEDs MOCVD GaN Wafer carriers

Visit: www.morgantechnicalceramics.com

The author Michael Hatcher is a freelance journalist based in Bristol, UK.