A method of forming a memory device, comprising: forming a first insulation layer on an upper surface of a semiconductor substrate forming a first conductive layer on the first insulation layer; forming a second insulation layer on the first conductive layer forming a trench into the second insulation layer that extends down to and exposes a portion of the first conductive layer; etching or oxidizing the exposed portion of the first conductive layer such that the exposed portion has a concave upper surface; forming first and second insulation spacers along sidewalls of the trench and over respective portions of the concave upper surface, wherein the first and second insulation spacers have inner surfaces that face each other and outer surfaces that face away from each other; forming a source region in a portion of the substrate below and between the first and second insulation spacers; removing the second insulation layer; removing portions of the first conductive layer to form a first block of the first conductive layer under the first insulation spacer and a second block of the first conductive layer under the second insulation spacer; forming a third insulation layer on side surfaces of the first and second blocks of the first conductive layer; completely filling a space between the inner surfaces of the first and second insulation spacers with insulation material; after the filling, forming a first conductive spacer along the outer surface of the first insulation spacer, and a second conductive spacer along the outer surface of the second insulation spacer; forming a first drain region in the substrate and adjacent to the first conductive spacer and a second drain region in the substrate and adjacent to the second conductive spacer. forming a first insulation layer on an upper surface of a semiconductor substrate forming a first conductive layer on the first insulation layer; forming a second insulation layer on the first conductive layer forming a trench into the second insulation layer that extends down to and exposes a portion of the first conductive layer; etching or oxidizing the exposed portion of the first conductive layer such that the exposed portion has a concave upper surface; forming first and second insulation spacers along sidewalls of the trench and over respective portions of the concave upper surface, wherein the first and second insulation spacers have inner surfaces that face each other and outer surfaces that face away from each other; forming a source region in a portion of the substrate below and between the first and second insulation spacers; removing the second insulation layer; removing portions of the first conductive layer to form a first block of the first conductive layer under the first insulation spacer and a second block of the first conductive layer under the second insulation spacer; forming a third insulation layer on side surfaces of the first and second blocks of the first conductive layer; completely filling a space between the inner surfaces of the first and second insulation spacers with insulation material; after the filling, forming a first conductive spacer along the outer surface of the first insulation spacer, and a second conductive spacer along the outer surface of the second insulation spacer; forming a first drain region in the substrate and adjacent to the first conductive spacer and a second drain region in the substrate and adjacent to the second conductive spacer. <EOS>