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The fluctuation in the minority carrier lifetime (MCLT) measurement is observed when monitoring the metal contamination for the furnace performing denuded zone formation, and the mechanism responsible for this phenomenon is examined in this paper. Among various possible causes, the oxygen precipitates are found to be the main contributor for this MCLT fluctuation because the amount of oxygen precipitates after denuded zone formation is strongly related to the initial oxygen concentration in the wafer and this makes the MCLT value liable to be affected even for tiny initial oxygen difference. A gate oxide recipe is suggested to be adopted for MCLT monitoring in furnace performing denuded zone formation to circumvent the problem. For the gate oxide recipe, not only is the monitoring result stable but it is feasible to produce MCLT test wafers with real products without sacrificing tool productivity. Index Terms--Denuded zone, gate oxide, metal contamination, minority carrier lifetime (MCLT), oxygen precipitates.

This paper is concerned with organic contamination from a partially fluorinated o-ring used in a furnace for a high-temperature process. The organic outgas was confirmed by Fourier transform infrared analysis of the furnace exhaust gas. Experiments from practical trench dynamic random access memory disclosed that outgassed organic contaminants from the nitride process would severely worsen the tunneling leakage current performance of the storage dielectric and lead to fatal yield loss even though the cell capacitance was almost uninfluenced. To eliminate this yield detractor requires several test runs prior to real production after installation of the partially fluorinated o-ring; otherwise, a fully fluorinated o-ring is needed. From a cost viewpoint, the latter is highly suggested. Index Terms--Fully fluorinatd o-ring, organic contamination, organic outgass, partially fluorinated o-ring high-temperature process.