Advanced RenewableEnergy Company LLC (ARC Energy) of Nashua, NH, USA, a provider of c-axis sapphire growth technologies and turnkey solutions for the LED solid-state lighting market, has announced 'CHES Foundations Series Part 2: Sapphire That Scales' as the latest publication in its CHES Foundations series, explaining the advantages of its CHES (Controlled Heat Extraction System) c-axis sapphire growth technology and furnaces.
The firm says that CHES achieves 75% or greater material utilization across large-diameter sapphire substrate sizes compared to 10-20% utilization for a-axis grown sapphire boules. CHES large-diameter wafers cost less, lead to higher LED production throughput per MOCVD run, and have properties (such as lower, more uniform bow) that enable lower cost per lumen, claims ARC.
"The industry must move to large-diameter wafers to reduce costs, but older sapphire technology has significant limitations moving in that direction," says ARC Energy senior VP Hap Hewes. "That's exactly why we developed CHES technology: to reduce costs for large-diameter LED sapphire wafers."
The high-brightness LED (HB-LED) industry is searching for dramatic cost savings to reduce the price of solid-state lighting to enable mass adoption by the general lighting market, notes ARC. A key component to reduce costs is moving to large-diameter substrates, similar to the move the silicon industry made over 20 years ago. 'Sapphire That Scales' outlines the advantages of moving to 150mm (6-inch) and 200mm (8-inch) substrates. A single MOCVD run simulated using 150mm wafers results in 55% more LED chips. With 200mm wafers the improvement increases to 77% more LED chips over using standard 50mm wafers.
Although large-diameter substrates have significant benefits, older sapphire growth technology has very low material utilization when growing these substrates, reckons ARC. Also, due to a non-uniform growth time signature, older technologies result in larger and uneven bowing (warp) during epitaxy process in a MOCVD reactor, reducing LED chip yield and requiring expensive workarounds, it adds.
CHES technology was designed to overcome the drawbacks of older sapphire technologies at large diameters. ARC says it provides high material utilization on the c-axis together with low defect levels. In addition, growing along the c-axis produces wafers with a single time signature, which can result in less bow and warp during epitaxy in the MOCVD reactor, the firm claims. CHES furnaces grow near-net-shape c-axis boules for 150mm and 200mm cores in production today, suiting HB-LED production on large-diameter sapphire substrates, ARC adds.
