Vertical DRAM cell and method
First Claim
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1. A method for forming a structure suitable for fabricating at least two semiconductor devices, comprising the steps of:
- (a) forming a trench to provide first and second walls in a substrate;
(b) forming elements of said at least two devices, said elements including first and second transistors, at least a portion of said first and second transistors formed along said first and second walls respectively; and
(c) etching between said first and second transistors to isolate said first and second transistors by removing material formed in said trench during said step of forming elements of said at least two devices, such that said first transistor comprises an element of one of said at least two devices and said second transistor comprises an element of another one of said at least two devices.
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Abstract
DRAM cells and arrays of cell on a semiconductor substrate, together with methods of fabrication, are disclosed wherein the cells are formed in pairs or quartets by excavating a trench or two trenches through the cell elements to split an original cell into two or four cells during the fabrication. The cells include vertical field effect transistors and capacitors along the trech sidewalls with word lines and bit lines crossing over the cells.
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Citations
37 Claims
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1. A method for forming a structure suitable for fabricating at least two semiconductor devices, comprising the steps of:
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(a) forming a trench to provide first and second walls in a substrate; (b) forming elements of said at least two devices, said elements including first and second transistors, at least a portion of said first and second transistors formed along said first and second walls respectively; and (c) etching between said first and second transistors to isolate said first and second transistors by removing material formed in said trench during said step of forming elements of said at least two devices, such that said first transistor comprises an element of one of said at least two devices and said second transistor comprises an element of another one of said at least two devices. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for forming a device comprising the steps of:
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(a) forming a trench in a substrate to provide first and second walls in said substrate; (b) forming first and second capacitor plates separated from said first and second walls, respectively, by a dielectric material; and (c) forming first and second transistors said first transistor controlling current flowing substantially parallel to said first wall and said second transistor controlling current flowing substantially parallel to said second wall. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method for forming a device comprising the steps of:
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(a) forming a first insulating layer on the surface of a substrate; (b) forming a conductor on the surface of said insulating layer; (c) forming a trench through said conductor, said insulating layer and into said substrate, said trench splitting said conductor into first and second conductors; (d) forming a second insulating layer on the surface of said trench; (e) forming a first semiconductive layer on the surface of said second insulating layer, said first semiconductive layer being separated from said first conductor and a first wall of said substrate by said second insulating layer; and (f) forming a second semiconductive layer on the surface of said second insulating layer, said second semiconductive layer being separated from said second conductor and a second wall of said substrate by said second insulating layer. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for forming a device comprising the steps of:
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(a) forming a trench in a substrate to define first and second walls; (b) forming a first insulating layer on said first and second walls; (c) forming a first conductive layer on said first insulating layer adjacent said first and second walls; (d) removing a portion of said first conductive layer adjacent said first and second walls; (e) removing the portion of said insulating layer exposed by the removal of a portion of said first conductive layer in step (d); (f) removing a portion of said insulating layer between said first conductive layer and said first and second walls, thus forming first and second crevices; (g) filling said first and second crevices with a conductive material; (h) forming first and second source regions in electrical contact with said conductive material; (i) forming a second insulating layer on said exposed portions of said first and second walls, said conductive material and said first layer of conductive material; (j) forming a second conductive layer on said second insulating layer; and (k) forming first and second drain regions in said first and second walls adjacent to said second insulating layer and spaced from said first and second source regions. - View Dependent Claims (32, 33, 34, 35, 36, 37)
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Specification