Self-aligned charge storage region formation for semiconductor device
Devices and methods for forming self-aligned charge storage regions are disclosed. In one embodiment, a method for manufacturing a semiconductor device comprises forming a layer of a nitride film stacked between two oxide films on a semiconductor substrate, and forming a gate electrode on the layer of the nitride film stacked between the two oxide films. In addition, the method comprises removing side portions of the nitride film such that a central portion of the nitride film below a center portion of the gate electrode remains, oxidizing the central portion of the nitride film, and forming charge storage layers in the side portions of the nitride film, where the charge storage layers are separated by the central portion of the nitride film.
1. A semiconductor device, comprising:
a nitride film stacked between central portions of two oxide films formed on a semiconductor substrate;
a gate electrode on the layer of the nitride film; and
two charge storage layers formed between the two oxide films wherein the two charge storage layers are separated by the nitride film,
wherein the outer edges of the nitride film are oxidized and the charge storage layers are formed on side portions of the nitride film.
2. The semiconductor device of claim 1 , wherein the two oxide films comprise:
a tunnel oxide film formed on the semiconductor substrate; and
a top oxide film formed on the nitride film.
3. The semiconductor device of claim 1 , wherein the nitride film is completely oxidized.
4. The semiconductor device of claim 1 , further comprising a source region and a drain region formed on the semiconductor substrate.
5. A flash memory device, comprising:
a nitride film stacked between central portions of two oxide films formed on a semiconductor substrate;
a gate electrode on the layer of the nitride film; and
two charge storage layers formed between the two oxide films separated by the nitride film,
wherein the outer edges of the nitride film are oxidized and the two charge storage layers are formed on side portions of the nitride film.
6. The flash memory device claim 5 , wherein the two oxide films comprise:
a tunnel oxide film formed on the semiconductor substrate; and
a top oxide film formed on the nitride film.