Memory arrays and methods used in forming a memory array
A memory array comprises a vertical stack comprising alternating insulative tiers and wordline tiers. The wordline tiers comprise gate regions of individual memory cells. The gate regions individually comprise part of a wordline in individual of the wordline tiers. Channel material extends elevationally through the insulative tiers and the wordline tiers. The individual memory cells comprise a memory structure laterally between the gate region and the channel material. Individual of the wordlines comprise laterally-outer longitudinal-edge portions and a respective laterally-inner portion laterally adjacent individual of the laterally-outer longitudinal-edge portions. The individual laterally-outer longitudinal-edge portions project upwardly and downwardly relative to its laterally-adjacent laterally-inner portion. Methods are disclosed.
1. A method used in forming a memory array, comprising:
forming a stack comprising vertically-alternating insulative tiers and wordline tiers, the insulative tiers comprising sacrificial material comprising opposing longitudinal edges comprising longitudinal shape of longitudinal outlines of individual wordlines to be formed in individual of the wordline tiers, the wordline tiers comprising a first conductive material of the individual wordlines to be formed;
selectively depositing from the first conductive material a second conductive material laterally beyond the opposing longitudinal edges of the insulative tiers, the selectively-deposited second conductive material projecting upwardly and downwardly into individual of the insulative tiers and comprising part of the individual wordlines;
after the selectively depositing, removing the sacrificial material from the insulative tiers; and
after the removing, forming insulator material to line and less-than-fill the individual insulative tiers.
2. The method of claim 1 comprising forming the insulator material to extend elevationally completely between upwardly and downwardly projecting portions of the selectively-deposited second conductive material of immediately vertically adjacent of the wordline tiers to form longitudinally-elongated voids in the individual insulative tiers.
3. The method of claim 1 wherein the first conductive material is laterally recessed from the opposing longitudinal edges of the insulative tiers at start of the selectively depositing.
4. The method of claim 1 wherein the first and second conductive materials are of the same composition relative one another.
5. The method of claim 1 comprising:
forming channel material to extend elevationally through the insulative tiers and the wordline tiers; and
forming individual memory cells of the array to comprise a gate region and a memory structure laterally between the gate region and the channel material.
6. The method of claim 5 comprising forming the memory structure to comprise:
a charge-blocking region of the individual memory cells elevationally along the individual gate regions;
charge-storage material of the individual memory cells elevationally along individual of the charge-blocking regions; and
insulative charge-passage material laterally between the channel material and the charge-storage material.
7. A method used in forming a memory array, comprising:
forming a stack comprising vertically-alternating insulative tiers and wordline tiers, the insulative tiers and the wordline tiers comprising opposing longitudinal edges comprising longitudinal shape of longitudinal outlines of individual wordlines to be formed in individual of the wordline tiers, the wordline tiers comprising a first sacrificial material, the insulative tiers comprising a second material of different composition from that of the first sacrificial material;
selectively depositing from the first sacrificial material a third sacrificial material laterally beyond the opposing longitudinal edges of the insulative tiers, the selectively-deposited third sacrificial material projecting upwardly and downwardly into individual of the insulative tiers, the third sacrificial material being of different composition from that of the second material;
forming a fourth material directly above and directly below the selectively-deposited third sacrificial material that projects upwardly and downwardly, respectively, into the individual insulative tiers, the fourth material being of different composition from those of the first and third sacrificial materials;
removing the first and third sacrificial materials selectively relative to the second and fourth materials to form: a) upwardly and downwardly extending cavities in the fourth material, and b) wordline-tier voids; and
forming conductive material in the cavities and in the wordline-tier voids and forming the individual wordlines to comprise the conductive material that is in the cavities and that is in the wordline-tier voids.
8. The method of claim 7 wherein the first and third sacrificial materials are of the same composition relative one another.
9. The method of claim 7 wherein the second and fourth materials are of the same composition relative on another.
10. The method of claim 7 wherein the conductive material completely fills the cavities and wordline-tier voids.
11. The method of claim 7 comprising, after the forming of the conductive material, removing the second and fourth materials selectively relative to the conductive material.
12. The method of claim 7 comprising:
forming channel material to extend elevationally through the insulative tiers and the wordline tiers; and
forming individual memory cells of the array to comprise a gate region and a memory structure laterally between the gate region and the channel material.
13. The method of claim 12 comprising forming the memory structure to comprise:
a charge-blocking region of the individual memory cells elevationally along the individual gate regions;
charge-storage material of the individual memory cells elevationally along individual of the charge-blocking regions; and
insulative charge-passage material laterally between the channel material and the charge-storage material.