Methods of forming mosfet devices using nitrogen-injected oxide layers to form gate insulating layers having different thicknesses

Abstract

In some embodiments of the inventive subject matter, methods include forming an oxide layer on a semiconductor substrate, injecting nitrogen into the oxide layer to form a nitrogen injection layer and to change the oxide layer to an oxynitride layer, removing a part of the oxynitride layer to leave a portion of the oxynitride layer in a first area and expose the nitrogen injection layer in a second area and forming an insulating layer comprising a portion on the portion of the oxynitride layer in the first area and a portion on the nitrogen injection layer in the second area. The insulating layer may have a higher dielectric constant than the oxide layer.