Patent ID: 7521751

Claim:
A nonvolatile memory device comprised of an array of memory transistors, each memory transistor having two source•drain regions formed in a semiconductor substrate and a plurality of insulation films including a nitride film for retaining charges inside and stacked between a gate electrode and a channel region formed in said semiconductor substrate between said two source•drain regions, and wherein a charge-store state of the memory transistor is changed by injecting hot carriers (high energy charges) into a local area of the nitride film at one or both of the source•drain regions side, wherein a density of a bond group of silicon and hydrogen (Si—H bond) of the nitride film is not more than 1×10 21 cm −3 ; and further wherein the nitride film comprises a bulk layer of a nitride film, and a structure transition layer having a chemical composition between a chemical composition of the bulk layer of the nitride film and a chemical composition of a bottom insulation film formed under the bulk layer and over the channel and having a Si—H bond density lower than that of the bulk layer of the nitride film and the chemical composition of the structure transition layer chances gradually from a chemical composition which is relatively close to that of the bottom insulation film to a chemical composition which is relatively close to that of the bulk layer of the nitride film.