Memory including blocking dielectric in etch stop tier

1. A vertical memory string, comprising:

a source;

an etch stop tier over the source, the etch stop tier comprising a blocking dielectric;

a vertically extending pillar extending through the etch stop tier and coupled to the source, wherein the blocking dielectric extends adjacent the pillar;

a stack of alternating dielectric tiers and conductive tiers over the blocking dielectric and the remaining portion of the etch stop tier; and

multiple vertically arranged memory cells having control gates formed in the conductive tiers, the multiple vertically arranged memory cells each comprising a respective charge storage structure adjacent the pillar.

2. The memory string of claim 1 , wherein the charge storage structures each comprise a floating gate.

3. The memory string of claim 1 , wherein the etch stop tier comprises a laterally extending recess adjacent the pillar, and wherein the blocking dielectric extends within the recess and separates the pillar from the remainder of the etch stop tier.

4. The memory string of claim 1 , wherein the etch stop tier comprises a metal oxide.

5. The memory string of claim 1 , wherein the etch stop tier comprises Aluminum Oxide (ALOX).

6. The memory string of claim 1 , wherein the blocking dielectric comprises silicon oxide.

7. The memory string of claim 1 , wherein the etch stop tier is formed over a select gate source (SGS) tier extending over the source.

8. The memory string of claim 1 , wherein the pillar comprises polysilicon.

9. A method of forming a vertical memory structure, comprising:

forming an etch stop tier over a source, the dielectric etch stop tier comprising a metal oxide;

forming alternating dielectric tiers and conductive tiers over the dielectric etch stop tier;

forming a vertical recess extending through the alternating dielectric and conductive tiers and into the etch stop tier;

forming a lateral recess in the etch stop tier;

forming a blocking dielectric within the lateral recess, the blocking dielectric extending over the bottom of the vertical recess to form a barrier between the vertical recess and the dielectric etch stop tier;

recessing at least a portion of the conductive tiers relative to the vertical recess and adjacent dielectric tiers to define charge storage device control gates within control gate recesses;

forming a multilayer dielectric at least within the control gate recesses;

forming a charge storage material of respective memory cells within the control gate recesses;

extending the vertical recess to the source;

forming a dielectric within the extended vertical recess; and

forming a pillar within the extended vertical recess, the extending from the source and adjacent the charge storage material of the memory cells.

10. The method of claim 9 , wherein forming a multilayer dielectric at least within the control gate recesses comprises forming an inner oxide material, a nitride material, and an outer oxide material along sidewalk; of the vertical recess and within the control gate recesses.

11. The method of claim 10 , wherein forming a charge storage material of respective memory cells within the control gate recesses comprises forming the charge storage material over the multilayer dielectric within the control gate recesses.

12. The method of claim 11 , wherein the charge storage material comprises polysilicon.

13. The method of claim 11 , wherein forming the charge storage material within the control gate recesses comprises forming the charge storage material within the vertical recess and within the control gate recesses; and

removing the deposited charge storage material outside of the charge storage recesses.

14. The method of claim 13 , further comprising after removing the deposited charge storage material outside of the charge storage recesses;

removing the outer oxide extending outside of the charge storage recesses to expose the nitride material outside of the charge storage recesses.

15. The method of claim 14 , further comprising selectively removing the nitride material outside of the charge storage recesses relative to the inner oxide.

16. The method of claim 15 , wherein the nitride material is selectively removed relative to the inner oxide by a hot phosphoric acid process or a hydrofluoric acid process.

17. The method of claim 13 , further comprising forming the etch stop tier over a source gate select (SGS) tier formed over the source, the SGS tier separated from the source by a separation material comprising oxide.

18. The method of claim 17 , wherein extending the vertical recess to the source comprises extending the vertical recess through the blocking dielectric and the etch stop tier, and through the SGS tier and separation material.

19. The method of claim 18 , further comprising forming a dielectric liner and a semiconductor pillar material within the extended vertical recess to form a channel material for the memory cells adjacent the pillar.

20. The method of claim 9 , wherein forming the blocking dielectric comprises using a High Aspect Ratio Process (HARP).

21. The method of claim 9 , wherein forming the blocking dielectric comprises utilizing a High Temperature Process (HTP).