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.