MULTI-LEVEL TYPE NON-VOLATILE MEMORY DEVICE

摘要

A multi-level type nonvolatile memory device is provided to restrain the distortion of data due to the leak of charge and to improve retention characteristics by controlling properly a tunneling probability using an improved barrier insulating layer structure composed of a plurality of barrier insulating layers with different tunneling characteristics. Source/drain regions(52) are formed in a semiconductor substrate(50). A gate electrode(64) is formed between the source/drain regions on the substrate. A tunnel insulating layer(54) and a blocking insulating layer are interposed between the substrate and the gate electrode. A plurality of charge storing layers(56a,56b,56c) are stacked between the blocking insulating layer and the tunnel insulating layer. A plurality of barrier insulating layers(58,60) are interposed between the charge storing layers.