We demonstrated the formation technique of highly reliable ultrathin oxidized silicon nitride film (34 Angstrom in oxide equivalent thickness) on three-dimensional cylindrical stacked capacitor cells. In situ H-2 cleaning and low-pressure chemical vapor deposition of silicon nitride using SiH2Cl2 and NH3 gases were successively carried out in a reactor; which can accommodate an 8 in. silicon wafer. The conduction current through the film was suppressed and the time-to-breakdown was substantially improved by the complete elimination of the bottom oxide. The intrinsic lifetime of the cylindrical stacked capacitors, which was comparable to that of the conventional stacked capacitors, was estimated to be long enough for use in 256 Mbit dynamic random access memory (DRAM). This result has revealed that the present single-wafer process is very effective End practical for the three-dimensional capacitor formation of the next generation DRAMs.