S. Krishnan, A. Tudhope, O. Laparra, and J. Grob, "Case Study: Ultraclean Gas Delivery," Semiconductor International, Vol 18, No 4, April 1995, pp 89-96.

Abstract: This study, done at VLSI Technology, compares a conventional gas delivery system to an ultraclean system — with surprising results. The contamination contributed by a conventional gas manifold and associated interconnects delivering process gases to a gate oxidation furnace was compared to that contributed by an ultraclean manifold. Moisture contamination was ~6X lower, while the oxygen contamination was ~3X lower than that of the conventional manifold. The conventional manifold contributed ~54 particles/scf which was ~20X more than that of the ultraclean manifold with a particle contribution of ~2.7 particles/scf. These results are for tests on one gas flow path on each panel. In the actual gate oxidation process, since greater than/equal to 33 gas lines (0₂, H₂, N₂, HCl) will be in use at any given time, the extent of contamination by the conventional panel is expected to increase.