Ultrathin Silicon Nitride Films Fabricated by Single‐Wafer Processing Using an SiH2Cl2 ‐  NH 3 ‐  H 2 System and In Situ  H 2 Cleaning

Abstract

We demonstrated the formation technique of highly reliable ultrathin oxidized silicon nitride film (34 A in oxide equivalent thickness) on three-dimensional cylindrical stacked capacitor cells. In situ 112 cleaning and low-pressure chemical vapor deposition of silicon nitride using SiH3C13 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 singlewafer process is very effective and practical for the three-dimensional capacitor formation of the next generation DRAMs.