RUGGED SURFACE POLYCRYSTALLINE SILICON FILM FORMED BY RAPID THERMAL CHEMICAL-VAPOR-DEPOSITION FOR DYNAMIC RANDOM-ACCESS MEMORY STACKED CAPACITOR APPLICATION

Polycrystalline silicon films with a rugged surface (rugged poly-Si), deposited by a single-wafer rapid thermal chemical vapor deposition (R TCVD) system suitable for 12 inch wafer fabrication, are studied and t he films have been successfully applied to bottom storage electrodes f or stacked capacitors in dynamic random access memory cells. Our data show that the rugged poly-Si is actually formed by the nucleation gene ration on the amorphous silicon surface and subsequent crystalline gro wth during the annealing step following deposition. We also determined that a wide temperature window exists for the formation of rugged pol y-Si (i.e., +/- 15 degrees C) using RTCVD, which is wider than that us ing low pressure chemical vapor deposition (LPCVD) (i.e., +/-3 degrees C) and ultra high vacuum chemical vapor deposition (UHVCVD) (i.e., +/ -10 degrees C). Stacked capacitors fabricated using rugged poly-Si and thin silicon oxide/silicon nitride dielectric film show that for a ru gged poly-Si storage electrode with a 60 nm top-layer and 645 degrees C annealing, an effective surface area of approximately 2.9 times that of a conventional poly-Si film electrode is obtained.