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P: Plasmaphysik

P 28: Sonstiges (Poster)

P 28.2: Poster

Montag, 9. März 1998, 18:00–20:00, P 2

The Influence of Gas Chemistry on Plasma-induced Damage — •Harald H. Richter¹, Massud-A. Aminpur², Andre Wolff¹, Roland Sorge¹, and Wolf-Dieter Rau¹ — ¹Institute for Semiconductor Physics, Walter-Korsing-Str. 2, 15230 Frankfurt (O), Germany — ²Present Address: AMD Saxony Manufacturing GmbH, Washingtonstr. 16 A/B, 01139 Dresden, Germany

Processing of advanced CMOS integrated circuits requires numbers of steps involving plasma processing, during which the initial quality of the thin gate oxide can be degraded. Advanced CMOS technologies use gate oxide thicknesses below 10 nm. In this paper, we study the effect of process induced damage on a 6 nm thick gate oxide caused by gate-definition reactive ion etching of poly-Si gate. Monitoring the density of interface traps through capacitance-voltage (CV) analysis and oxide breakdown measurements are a sensitive index of these plasma-induced damage phenomena. The results indicate differences in charging damage with different etch chemistries used for poly-Si gate patterning process (chlorine, bromine and iodine-based). We attribute this sensitivity to the different bias voltages during dry etching. Iodine-containing discharges are characterized by very low self-bias voltages compared to other halogen-containing plasmas, resulting in smaller ion energies. Consequently hydrogen iodine (HI) chemistry provides a low damage etch process without trenching.