A Synergistic Approach to Environmental Concerns in Large Scale MOCVD Processes

Abstract

AbstractProcesses used in the production of epitaxial III-V semiconducting materials employ a wide variety of materials that are environmentally hazardous. As production volumes increase, the need to manage these materials becomes a serious concern. As the leading supplier of production scale single and multi-wafer MOCVD systems, we have taken the approach of minimizing the generation of waste by designing our reactor for high reactant utilization efficiency, and then trapping the remainder so that the exhaust stream is clean. We have paid particular attention to both operational efficiency and operator safety. The traps may be simply removed and replaced, with cleaning being performed off line. The trapped materials are reduced to an inert state for subsequent commercial disposal; this is particularly important for phosphorus, which can be highly flammable if improperly handled. The reactor chamber deposits occur below the wafer level and typically are cleaned only after several hundred deposition cycles. These factors contribute to a quick cycle time and high uptime, both of which increase throughput. These issues become more important as the reactor size is increased and when multiple shifts are utilized. These points are exemplified by our operational experience with our new Enterprise series, which holds four 100mm wafers (or seventeen 50mm wafers) per run. We will discuss the progressive trapping of solid As and P compounds and those hydride gases which are not completely decomposed in the reaction chamber. The use of computer modeling to scale the process to larger dimensions and to optimize the deposition conditions will also be discussed.