Abstract: With keeping an atmosphere including oxygen within a chamber and with a wafer kept at a low temperature, plasma generated within the chamber is biased toward the wafer, and the wafer is subjected to the plasma. A semiconductor layer exposed on the wafer is oxidized into an oxide film. Thus, an oxide film can be formed even at room temperature differently from thermal oxidation. This oxidation is applicable to recovery of an implantation protection insulating film having been etched in cleaning a photoresist film, relaxation of a step formed between polysilicon films, relaxation of a step formed within trench and the like. Also, before removing a photoresist film used for forming a gate electrode including a metal, a contamination protection film can be formed by this oxidation with the photoresist film kept.

Abstract: A memory cell transistor and a trench capacitor are provided in a memory region, and both transistors of CMOS are provided in a logic circuit region. There are provided a bit line contact 31 and a bit line 32 extending on an inter-level dielectric 30. In a memory cell transistor, a source diffusion layer 18 is covered with two dielectric sidewalls 25a and 25b in the memory cell transistor so that no silicide layer is formed on the source diffusion layer 18. A plate contact 31 is provided to pass through the inter-level dielectric 30 and connect a shield line 33 to a plate electrode 16b. The shield line 33 is arranged in the same interconnect layer as the bit line 32.