Flash memory device and a method for fabricating the same
First Claim
1. A method for forming a flash memory device, comprising:
- sequentially forming a charge-storage dielectric layer and an etching mask layer on a semiconductor substrate;
patterning the etching mask layer and the charge-storage layer, thereby exposing regions of the semiconductor substrate;
forming isolation regions in the exposed regions of the semiconductor substrate, the isolation regions defining active regions;
removing the patterned etching mask layer;
forming an upper conductive layer overlying the patterned charge-storage layer; and
patterning the upper conductive layer and the patterned charge-storage layer, thereby forming a gate line intersecting the isolation regions and the active regions.
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Abstract
A flash memory having a charge-storage dielectric layer and a method for forming the same are provided. According to one embodiment, charge-storage dielectric layers are formed over the first and second active regions. The charge-storage layer over the first active region is not connected to the charge-storage layer over the second active region. A gate line overlies the charge-storage layer and extends across the first and second active regions and the isolation region. The charge-storage layer can be formed only where a gate line intersects an active region of a semiconductor substrate, not on an isolation region. Thus, undesirable influence or disturbance from adjacent memory cells can be avoided.
9 Citations
17 Claims
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1. A method for forming a flash memory device, comprising:
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sequentially forming a charge-storage dielectric layer and an etching mask layer on a semiconductor substrate;
patterning the etching mask layer and the charge-storage layer, thereby exposing regions of the semiconductor substrate;
forming isolation regions in the exposed regions of the semiconductor substrate, the isolation regions defining active regions;
removing the patterned etching mask layer;
forming an upper conductive layer overlying the patterned charge-storage layer; and
patterning the upper conductive layer and the patterned charge-storage layer, thereby forming a gate line intersecting the isolation regions and the active regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
wherein the lower conductive layer is patterned when the etching mask layer and the charge-storage layer are patterned; - and
wherein the patterned lower conductive layer is patterned when the upper conductive layer and the patterned charge-storage layer are patterned.
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4. The method of claim 1, wherein forming the isolation regions in the exposed regions of the semiconductor substrate further comprises:
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etching the exposed regions of the semiconductor substrate to form trenches therein; and
filling the trenches with a trench-filling insulating layer.
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5. The method of claim 4, further comprising:
planarizing the trench-filling insulating layer until a top surface of the patterned etching mask layer is exposed.
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6. The method of claim 5, wherein the charge-storage layer includes a lower oxide layer, a nitride layer, and an upper oxide layer (ONO layer) sequentially stacked on the semiconductor substrate.
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7. The method of claim 1, wherein forming the isolation regions on the exposed regions of the semiconductor substrate further includes:
forming a thermal oxide layer on the exposed semiconductor substrate.
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8. The method of claim 7, wherein the charge-storage layer includes a lower oxide layer, a nitride layer, and an upper oxide layer (ONO layer) sequentially stacked on the semiconductor substrate.
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9. A method for forming a flash memory comprising:
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sequentially forming a charge-storage dielectric layer, a lower conductive layer, and an etching mask layer on a semiconductor substrate;
patterning the etching mask layer, the lower conductive layer, and the charge-storage dielectric layer, thereby exposing regions of the semiconductor substrate;
etching the exposed regions of the semiconductor substrate to form trenches therein;
filling the trenches with a trench-filling insulating layer;
planarizing the trench-filling insulating layer until the patterned etching mask layer is exposed, thereby forming isolation regions defining active regions therebetween;
removing the exposed patterned etching mask layer;
forming an upper conductive layer on the isolation regions and the patterned lower conductive layer; and
patterning the upper conductive layer, the patterned lower conductive layer, and the patterned charge-storage layer, thereby forming gate lines intersecting the isolation regions and active regions. - View Dependent Claims (10)
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11. A method for forming flash memory device comprising:
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forming a charge-storage layer on a semiconductor substrate;
patterning the charge-storage layer to expose regions of the semiconductor substrate, forming isolation regions in the exposed regions of the semiconductor substrate, the isolation regions defining active regions therebetween, the patterned charge-storage layer self-aligned with the isolation regions;
forming a conductive layer overlying the patterned charge-storage layer; and
patterning the conductive layer and the patterned charge-storage layer to form gate lines overlying the patterned charge-storage layer, the gale lines extending across the active regions. - View Dependent Claims (12)
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13. A method for fanning a flash memory device, comprising:
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sequentially forming a lower oxide layer, a nitride layer, an upper oxide layer (ONO layer) as a charge-storage layer and an etching mask layer an a semiconductor substrate;
patterning the etching mask layer and the ONO layer, thereby exposing regions of the semiconductor substrate;
etching the exposed regions of the semiconductor substrate to form trenches therein, and filling the trenches with a trench-filling insulating layer to form trench isolation regions defining active regions;
removing the patterned etching musk layer; and
forming an upper conductive layer and the patterned ONO layer, thereby forming a gate line intersecting the trench isolation regions and the active regions. - View Dependent Claims (14, 15, 16, 17)
planarizing the trench-filling insulating layer until a top surface of the patterned etching mask layer is exposed.
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16. The method of claim 13, further comprising:
forming a thermal oxide layer overlying the trenches.
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17. The method of claim 13, further comprising:
sequentially forming a thermal oxide and a nitride liner overlying the trenches.
Specification