CHARACTERISTICS OF THE NO DIELECTRIC FILM WITH LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION IN-SITU NITRIDATION

We investigated the formation of the thin NO dielectric films by in-si tu nitridation of native oxide, and subsequent deposition of silicon n itride in the low pressure chemical vapor deposition systems for the a pplication to the capacitors in high density dynamic random access mem ory. The native oxide was nitrided at elevated temperatures of 690 or 780 degrees C in the flowing ammonia gas atmosphere, and nitride was d eposited by flowing silane gas additionally immediately after the nitr idation process. By in-situ nitridation process, we could obtain 5 and 4.5 nm thick (equivalent oxide thickness) nitride/oxide (NO) dielectr ic films. These films were characterized to be electrically more relia ble than the conventional oxide/nitride/oxide (ONO) films of the same equivalent oxide thickness. The nitrided NO films also showed lower le akage current and higher breakdown voltage than conventional ONO films . We obtained electrically most reliable NO films by loading the wafer at 400 degrees C and nitriding the native oxide at 780 degrees C.