Methods of forming non-volatile memory devices

A method of forming a non-volatile memory device, the method comprising:

• forming a dielectric layer including an oxide layer and a nitride layer on a substrate;
• transforming at least a portion of the nitride layer extending across at least a major lateral extent of the dielectric layer to include added oxygen;
• forming a charge storage layer on the dielectric layer;
• forming a blocking insulating layer on the charge storage layer;
• and
• forming a gate electrode on the blocking insulating layer,
• wherein the transforming at least a portion of the nitride layer comprises oxidizing the nitride layer,
• wherein the nitride layer is fully oxidized,
• wherein an interface of the substrate and the oxide layer includes a first nitrogen accumulation region, and an interface of the oxide layer and the oxidized nitride layer includes a second nitrogen accumulation region having a lower nitrogen concentration than the first nitrogen accumulation region, and
• wherein the at least one insulating layer of the blocking insulating layer has a higher dielectric constant than a highest dielectric constant of at least a major portion of the dielectric layer.