Methods of manufacturing non-volatile memory devices that can reduce or prevent loss of charges stored in a charge storage layer and/or that can improve charge storage capacity by neutral beam irradiation of an insulating layer are disclosed. The methods include forming a tunneling insulating layer on a substrate, forming a charge storage layer on the tunneling insulating layer, forming a blocking insulating layer on the charge storage layer, irradiating the blocking insulating layer and/or the tunneling insulating layer with a neutral beam, and forming a gate conductive layer on the blocking insulating layer.