The formation of germanium nanocrystals embedded in silicon-oxygen-nitride with distributed charge storage elements is proposed. A large memory window was observed due to isolated Ge nanocrystals in the SiON gate stack layer. The Ge nanocrystals were nucleated after a high-temperature oxidized SiGeN layer. The Ge nanocrystals embedded in the SiON stack layer exhibited nonvolatile memory characteristics with the obvious threshold voltage shift under a bidirectional voltage sweep. Also, the manufacturing technology using the sequent high-temperature oxidation of the a-Si layer and the direct oxidation of the SiGeN layer is proposed, respectively, for the formation of a blocking oxide layer to enhance the performance of nonvolatile memory devices. The reliability characteristics, including retention time and endurance, are also advisable for the application of nonvolatile memory device. (c) 2007 The Electrochemical Society.