Patent ID: 9640403
Date: 2017-05-02
CPC Classifications: H01L

Claim:
1. A low electric field source erasable non-volatile memory unit comprising: a substrate including an upper surface, with the substrate further including a source diffusion region and a drain diffusion region, with the source diffusion region including a heavily-doped region and a lightly-doped region extending outwards from the heavily-doped region, the heavily-doped region has a first width, wherein the lightly-doped region of the source diffusion region is formed on a groove portion defined inside the substrate and under the upper surface of the substrate and the lightly-doped region is formed on a sidewall of the groove portion, the sidewall of the groove portion is connected to the upper surface of the substrate, and the heavily-doped region is formed under the groove portion; a first dielectric layer formed on the upper surface of the substrate and located on the drain diffusion region side; a tunnel dielectric layer formed on the upper surface of the substrate and located on the source diffusion region side, the tunnel dielectric layer being thicker than the first dielectric layer; a source insulating layer formed on the upper surface of the substrate, the source insulating layer being thicker than the tunnel dielectric layer; a select gate formed on the first dielectric layer; a floating gate formed on a face of the tunnel dielectric layer, with the floating gate partially overlapped with the lightly-doped region of the source diffusion region and misaligned from the heavily-doped region of the source diffusion region by a distance; a second dielectric layer formed on a face of the floating gate; and a control gate formed on the face of the floating gate and covering the heavily-doped region and at least partially the lightly-doped region, with the control gate and the floating gate being insulating to each other by the second dielectric layer, the control gate having a second width greater than the first width of the heavily-doped region.