Method to seperate storage regions in the mirror bit device
Devices and methods for isolating adjacent charge accumulation layers in a semiconductor device are disclosed. In one embodiment, a semiconductor device comprises a bit line formed in a semiconductor substrate, a charge accumulation layer formed on the semiconductor substrate, a word line formed on the charge accumulation layer across the bit line, and a channel region formed in the semiconductor substrate below the word line and between the bit line and its adjacent bit line. For the semiconductor device, the charge accumulation layer is formed above the channel region in a widthwise direction of the word line, and a width of the word line is set to be narrower than a distance between an end of the channel region and a central part of the channel region in a lengthwise direction of the word line.
1. A semiconductor device comprising:
a bit line formed in a semiconductor substrate;
a charge accumulation layer formed on the semiconductor substrate;
a word line formed on the charge accumulation layer and across the bit line; and
a channel region formed in the semiconductor substrate below the word line and between the bit line and an adjacent bit line, wherein the charge accumulation layer is formed above the channel region in a widthwise direction of the word line, and wherein a width of the word line is set to be narrower than a distance between an end of the channel region and a central part of the channel region in a lengthwise direction of the word line.
2. The semiconductor device of claim 1 , wherein a portion of the charge accumulation layer formed above the central part of the channel region is removed in the lengthwise direction of the word line to separate the charge accumulation layer from a neighboring charge accumulation layer.
3. The semiconductor device of claim 1 , further comprising:
a tunnel insulating film formed between the semiconductor substrate and the charge accumulation layer; and
a top insulating film formed on the charge accumulation layer, wherein the charge accumulation layer is adjoined to a hollow section formed between the charge accumulation layer and its neighboring charge accumulation layer.
4. The semiconductor device of claim 3 , wherein the hollow section is filled with an insulating material.
5. The semiconductor device of claim 1 , wherein the charge accumulation layer comprises a nitride film.
6. A semiconductor device comprising:
a bit line formed in a semiconductor substrate;
a charge accumulation layer formed on the semiconductor substrate;
a word line formed on the charge accumulation layer and across the bit line; and
a channel region formed in the semiconductor substrate below the word line and between the bit line and an adjacent bit line, wherein the charge accumulation layer is formed above the channel region in a widthwise direction of the word line, and wherein a first width of the charge accumulation layer above the channel region is greater than a second width of the charge accumulation layer above the channel region.
7. The semiconductor device of claim 6 , wherein a portion of the charge accumulation layer formed above a central part of the channel region is removed in the lengthwise direction of the word line to separate the charge accumulation layer from a neighboring charge accumulation layer.
8. The semiconductor device of claim 6 , further comprising:
a tunnel insulating film formed between the semiconductor substrate and the charge accumulation layer; and
a top insulating film formed on the charge accumulation layer, wherein the charge accumulation layer is adjoined to a hollow section formed between the charge accumulation layer and its neighboring charge accumulation layer.
9. The semiconductor device of claim 8 , wherein the hollow section is filled with an insulating material.
10. The semiconductor device of claim 6 , wherein the charge accumulation layer comprises a nitride film.
11. The semiconductor device of claim 6 , wherein a width of the charge accumulation layer formed over the channel region in the widthwise direction of the wordline is set to be narrower in a curved line from an end of the channel region towards a central part of the channel region in the lengthwise direction of the wordline.
12. The semiconductor device of claim 6 , wherein a portion of the charge accumulation layer formed above a central part of the channel region is removed in the lengthwise direction of the word line such that the charge accumulation layer is not separated from a neighboring charge accumulation layer.