3D virtual ground memory and manufacturing methods for same
Memory devices are implemented within a vertical memory structure, comprising a stack of alternating layers of insulator material and word line material, with a series of alternating conductive pillars and insulating pillars disposed through stack. Data storage structures are disposed on inside surfaces of the layers of word line material at cross-points of the insulating pillars and the layers of word line material. Semiconductor channel material is disposed between the insulating pillars and the data storage structures at cross-points of the insulating pillars with the layers of word line material. The semiconductor channel material extends around an outside surface of the insulating pillars, contacting the adjacent conductive pillars on both sides to provide source/drain terminals.
1. A vertical memory structure, comprising:
a stack of alternating layers of insulator material and layers of word line material;
a series of alternating conductive pillars and insulating pillars disposed through the stack, the series including at least a first conductive pillar, a first insulating pillar adjacent to the first conductive pillar and a second conductive pillar adjacent to the first insulating pillar, wherein an outside surface of the first insulating pillar is arcuate in a plane parallel to the layers of word line material;
data storage structures disposed on inside surfaces of the layers of word line material at cross-points of the first insulating pillar and the layers of word line material;
semiconductor channel material between the first insulating pillar and the data storage structures at cross-points of the first insulating pillar with the layers of word line material, the semiconductor channel material extending around the outside surface of the first insulating pillar and contacting the first conductive pillar and the second conductive pillar; and
conductor filled slots disposed in intervals along the series of alternating conductive pillars and insulating pillars, and extending through the stack to contact a conductive layer beneath the stack, wherein the conductor filled slots are elongated in a direction orthogonal to the series of alternating conductive pillars and insulating pillars.
2. The vertical memory structure of claim 1 , wherein the inside surfaces of the layers of word line material adjacent to the first insulating pillar are recessed relative to inside surfaces of the layers of insulator material adjacent to the first insulating pillar, forming recesses between the layers of insulator material, and wherein the semiconductor channel material and the data storage structures are disposed in the recesses.
3. The vertical memory structure of claim 2 , wherein the semiconductor channel material disposed in the recesses is discontinuous in a vertical direction across the layers of insulator material.
4. The vertical memory structure of claim 1 , including a plurality of series of alternating conductive pillars and insulating pillars disposed through the stack, the conductive pillars in the plurality of series being arranged in an array, the plurality of series including the series.
5. The vertical memory structure of claim 4 , wherein the plurality of series in the array are arranged in a plurality of distinct subarrays of the array, each distinct subarray including at least one series in the plurality of series, and further including:
a plurality of conductive strips disposed in a pillar select layer over the stack, including for each distinct subarray of the array, a corresponding conductive strip of the plurality of conductive strips, and including for each distinct subarray of the array a plurality of vertical channel structures through the corresponding conductive strip contacting respective conductive pillars in the distinct subarrays;
a plurality of bit line conductors disposed over the pillar select layer over the stack, each bit line conductor having contacts to one vertical channel transistor in a plurality of vertical channel transistors in each of the distinct subarrays.
6. The vertical memory structure of claim 5 ,
wherein the conductive pillars in the plurality of series of alternating conductive pillars and insulating pillars connect to the conductive layer through a PN junction.
7. The vertical memory structure of claim 6 , wherein the conductive pillars comprise n-type semiconductor and the conductive layer beneath the stack comprises p-type semiconductor.
8. The vertical memory structure of claim 1 , wherein semiconductor channel material between the insulating pillars and the data storage structures is discontinuous between the layers of word line material in the stack.
9. The vertical memory structure of claim 1 , wherein each of the first insulating pillar, the first conductive pillar and the second conductive pillar has a vertical axis that is aligned along a same horizontal direction.
10. The vertical memory structure of claim 1 , wherein the alternating conductive pillars include cylindrical conductive pillars.
11. The vertical memory structure of claim 10 , wherein at least one of the cylindrical conductive pillars is elliptically shaped.
12. The vertical memory structure of claim 10 , wherein at least one of the cylindrical conductive pillars is circularly shaped.
13. A vertical memory structure, comprising:
a stack of alternating layers of insulator material and layers of word line material;
a plurality of distinct series of alternating cylindrical conductive pillars and cylindrical insulating pillars disposed through the stack, the conductive pillars in the plurality of distinct series being arranged in an array and in a plurality of distinct subarrays of the array, each distinct subarray including at least one distinct series in the plurality of series, each distinct series in the plurality of distinct series including at least a first conductive pillar, a first insulating pillar adjacent to the first conductive pillar and a second conductive pillar adjacent to the first insulating pillar;
data storage structures disposed on inside surfaces of the layers of word line material at cross-points of the insulating pillars in the plurality of distinct series and the layers of word line material;
semiconductor channel material between the insulating pillars in the plurality of distinct series and the data storage structures at cross-points of the insulating pillars in the plurality of distinct series with the layers of word line material, the semiconductor channel material extending around outside surfaces of the insulating pillars in the plurality of distinct series and contacting adjacent conductive pillars on both sides in the plurality of distinct series;
a plurality of conductive strips disposed in a pillar select layer over the stack, including for each distinct subarray of the array, a corresponding conductive strip of the plurality of conductive strips, and including for each distinct subarray of the array a plurality of vertical channel structures through the corresponding conductive strip contacting respective conductive pillars in the distinct subarray;
a plurality of bit line conductors disposed over the pillar select layer over the stack, each bit line conductor having contacts to one vertical channel transistor in a plurality of vertical channel transistors in each of the distinct subarrays; and
conductor filled slots disposed in intervals along the plurality of series of alternating conductive pillars and insulating pillars, and extending through the stack to contact a conductive layer beneath the stack, wherein the conductor filled slots are elongated in a direction orthogonal to the plurality of series of alternating conductive pillars and insulating pillars.
14. The vertical memory structure of claim 13 , wherein the inside surfaces of the layers of word line material adjacent to the insulating pillars are recessed relative to inside surfaces of the layers of insulator material adjacent to the insulating pillars, forming recesses between the layers of insulator material, and wherein the semiconductor channel material and the data storage structures are disposed in the recesses.
15. The vertical memory structure of claim 14 , wherein the semiconductor channel material disposed in the recesses is discontinuous in a vertical direction across the layers of insulator material.
16. The vertical memory structure of claim 13 ,
wherein the conductive pillars in the plurality of distinct series of alternating conductive pillars and insulating pillars connect to the conductive layer through a PN junction.
17. The vertical memory structure of claim 16 , wherein the conductive pillars comprise n-type semiconductor and the conductive layer beneath the stack comprises p-type semiconductor.
18. The vertical memory structure of claim 13 , wherein semiconductor channel material between the insulating pillars and the data storage structures is discontinuous between the layers of word line material in the stack.
19. The vertical memory structure of claim 13 , wherein at least one of the cylindrical conductive pillars is elliptically shaped.
20. The vertical memory structure of claim 13 , wherein at least one of the cylindrical conductive pillars is circularly shaped.