Electronic device including discontinuous storage elements
View Patent ↗An electronic device can include discontinuous storage elements that lie within a trench. In one embodiment, the electronic device can include a substrate having a trench that includes a wall and a bottom. The electronic device can also include a portion of discontinuous storage elements that lie within the trench. The electronic device can also include a first gate electrode, wherein at least one discontinuous storage element lies along the wall of the trench at an elevation between and upper surface of the first gate electrode and a primary surface of the substrate. The electronic device can also include a second gate electrode overlying the first gate electrode and the primary surface of the substrate. In another embodiment, a conductive line can be electrically connected to one or more rows or columns of memory cells, and another conductive line can be more rows or more columns of memory cells.
1. An electronic device comprising:
a substrate including a first trench that includes a wall and a bottom and extends from a primary surface of the substrate;
discontinuous storage elements, wherein a first portion of the discontinuous storage elements lies within the first trench, and a second portion of the discontinuous storage elements overlies the primary surface outside of the first trench;
a first gate electrode having an upper surface that lies below the primary surface of the substrate; and
a second gate electrode overlying the first gate electrode and the primary surface of the substrate, wherein:
within a memory cell, a first discontinuous storage element and a second discontinuous storage element lie within the first trench at elevations higher than the upper surface of the first gate electrode;
all of the first discontinuous storage element lies at an elevation higher than all of the second discontinuous storage element; and
the second portion of the discontinuous storage element lies between the second gate electrode and the primary surface of the substrate.
2. The electronic device of claim 1 , wherein at least a portion of the second gate electrode extends at least partly into the first trench.
3. The electronic device of claim 2 , further comprising a third gate electrode, wherein:
the substrate further includes a second trench that is spaced apart from the first trench, wherein the second trench includes a wall and a bottom and extends from the primary surface of the substrate;
a third portion of the discontinuous storage elements lies at least within the second trench; and
the third gate electrode has an upper surface that lies below the primary surface of the substrate, wherein at least a part of the third portion of the discontinuous storage elements lies along the wall of the second trench at an elevation between the upper surface of the third gate electrode and the primary surface.
4. The electronic device of claim 3 , further comprising:
a first doped region lying within the substrate below the first trench; and
a second doped region lying within the substrate below the second trench.
5. The electronic device of claim 4 , further comprising a third doped region lying along the primary surface of the substrate between the first and second trenches.
6. The electronic device of claim 5 , wherein the third doped region extends to the walls of the first and second trenches.
7. The electronic device of claim 5 , wherein the third doped region is spaced apart from the walls of the first and second trenches.
8. The electronic device of claim 4 , wherein:
a first charge storage region includes a first discontinuous storage element within the first portion of the discontinuous storage elements, wherein the first discontinuous storage element lies closer to the upper surface of the first gate electrode than the first doped region;
a second charge storage region includes a second discontinuous storage element within the first portion of the discontinuous storage elements, wherein the second discontinuous storage element lies closer to the first doped region than the upper surface of the first gate electrode, and wherein the second charge storage region is spaced apart from the first charge storage region;
a third charge storage region includes a third discontinuous storage element within the third portion of the discontinuous storage elements, wherein the third discontinuous storage element lies closer to the upper surface of the third gate electrode than the second doped region; and
a fourth charge storage region includes a fourth discontinuous storage element within the third portion of the discontinuous storage elements, wherein the fourth discontinuous storage element lies closer to the second doped region than the upper surface of the third gate electrode, and wherein the fourth charge storage region is spaced apart from the third charge storage region,
wherein an individual memory cell of the electronic device includes the first, second, third, and fourth charge storage regions.
9. The electronic device of claim 3 , wherein the second gate electrode overlies the first gate electrode, the third gate electrode, and a portion the substrate between the first and second trenches.
10. The electronic device of claim 3 , further comprising a fourth gate electrode spaced apart from the third gate electrode, wherein:
the second gate electrode overlies the first gate electrode and a first portion of the substrate between the first and second trenches;
the fourth gate electrode overlies the third gate electrode and a second portion of the substrate between the first and second trenches;
from a top view, each of the first, second, third and fourth gate electrodes has a length and a width that is smaller than the length; and
the lengths of the first, second, third, and fourth gate electrodes are substantially parallel to one another.
11. The electronic device of claim 1 , further comprising an army, wherein within the array, the discontinuous storage elements overlie substantially all of the primary surface outside of the trenches and along substantially all of the wall of the first trench.
12. The electronic device of claim 1 , wherein the discontinuous storage elements comprise silicon nanocrystals or metal nanoclusters, wherein each discontinuous storage element is no greater than approximately 10 nm in each and every dimension.
13. The electronic device of claim 1 , wherein:
from a top view, the first trench has a length and a width that is smaller than the length; and
from a cross-sectional view along a plane parallel to the width of the first trench, at least three different discontinuous storage elements of the discontinuous storage elements overlie the bottom of the first trench.
14. The electronic device of claim 1 , wherein from a cross-sectional view:
the first gate electrode includes portions that are spaced apart from each other within the first trench;
no portion of the first gate electrode overlies a center of the bottom of the first trench; and
the portions of the first gate electrode include curved outer surfaces that face each other.
15. An electronic device comprising:
a substrate including a first trench and a second trench that are spaced apart from each other; wherein each of the first and second trenches includes a wall and a bottom and extends from a primary surface of the substrate;
a first doped region lying within the substrate along the bottom of the first trench;
a second doped region lying within the substrate along the bottom of the second trench;
a first dielectric layer lying along the walls and bottoms of the first and second trenches;
discontinuous storage elements, wherein:
a first portion of the discontinuous storage elements lie at least within the first trench;
a second portion of the discontinuous storage elements lie at least within the second trench; and
a third portion of the discontinuous storage elements overlie the primary surface of the substrate, wherein the third portion of the discontinuous storage elements is contiguous with each of the first and second portions of the discontinuous storage elements;
a second dielectric layer adjacent to the discontinuous storage elements within the first and second trenches;
a first gate electrode lying within the first trench and having an upper surface that lies below the primary surface of the substrate, wherein at least a part of the first portion of the discontinuous storage elements lies along the wall of the first trench at an elevation between the upper surface of the first gate electrode and the primary surface;
a second gate electrode lying within the second trench and having an upper surface that lies below the primary surface of the substrate, wherein at least a part of the second portion of the discontinuous storage elements lies along the wall of the second trench at an elevation between the upper surface of the second gate electrode and the primary surface;
a third dielectric layer including a first portion overlying the first gate electrode within the first trench and a second portion overlying the second gate electrode within the second trench; and
a third gate electrode overlying at least one of the first gate electrode or the second gate electrode, wherein the third gate electrode lies at least partly within the first trench and the second trench.