JP2977522B

Methods of forming integrated circuit capacitors having composite oxide-nitride-oxide (ONO) dielectric layers include the steps of forming a first electrically insulating layer on a semiconductor substrate and then forming a first conductive layer on the first electrically insulating layer. The first conductive layer and the first electrically insulating layer are then etched in sequence to define an opening in the first conductive layer which exposes upper and lower surfaces of the first conductive layer extending adjacent the opening. The exposed upper and lower surfaces of the first conductive layer are then cleaned to remove a native oxide film therefrom. A preferred composite dielectric layer is then formed on the first conductive layer. The composite dielectric layer comprises a first oxide layer which contacts the cleaned upper and lower surfaces of the first conductive layer, a nitride layer which contacts the first oxide layer and a second oxide layer which contacts the nitride layer. A step is then performed to form a second conductive layer on the composite dielectric layer. Here, the step of forming a composite dielectric layer includes the step of exposing the first conductive layer to an oxygen containing atmosphere. Preferably, the cleaned upper and lower surfaces of the first conductive layer are exposed to an atmosphere containing 30-100% oxygen by weight and 0-70% nitrogen by weight.