Elevationally-extending string of memory cells individually comprising a programmable charge storage transistor and method of forming an elevationally-extending string of memory cells individually comprising a programmable charge storage transistor

1. An elevationally-extending string of memory cells individually comprising a programmable charge storage transistor, comprising:

an upper stack elevationally over a lower stack, the upper and lower stacks individually comprising vertically-alternating tiers comprising control gate material of individual charge storage field effect transistors vertically alternating with insulating material;

an upper stack channel pillar extending through multiple of the vertically-alternating tiers in the upper stack and a lower stack channel pillar extending through multiple of the vertically-alternating tiers in the lower stack; tunnel insulator, charge storage material, and control gate blocking insulator being laterally between the respective upper and lower stack channel pillars and the control gate material;

a conductive interconnect comprising conductively-doped semiconductor material elevationally between and electrically coupling the upper and lower stack channel pillars together, the conductively-doped semiconductor material comprising conductivity-producing dopant therein; and

an asymmetric diffusion barrier allowing greater diffusion of the conductivity-producing dopant from the conductively-doped semiconductor material into the upper stack channel pillar than diffusion, if any, of said dopant from the conductively-doped semiconductor material into the lower stack channel pillar.

2. The elevationally-extending string of memory cells of claim 1 wherein the diffusion barrier is within the conductive interconnect.

3. The elevationally-extending string of memory cells of claim 1 wherein the diffusion barrier is within the conductive interconnect and within the lower stack channel pillar.

4. An elevationally-extending string of memory cells individually comprising a programmable charge storage transistor, comprising:

an upper stack elevationally over a lower stack, the upper and lower stacks individually comprising vertically-alternating tiers comprising control gate material of individual charge storage field effect transistors vertically alternating with insulating material;

an upper stack channel pillar extending through multiple of the vertically-alternating tiers in the upper stack and a lower stack channel pillar extending through multiple of the vertically-alternating tiers in the lower stack; tunnel insulator, charge storage material, and control gate blocking insulator being laterally between the respective upper and lower stack channel pillars and the control gate material; and

a conductive interconnect comprising conductively-doped semiconductor material elevationally between and electrically coupling the upper and lower stack channel pillars together, the conductively-doped semiconductor material comprising a first conductivity-producing dopant, the conductive interconnect comprising a lower half thereof having a conductive region comprising at least one of (a) conductive material below the conductively-doped semiconductor material, or (b) a second non-p-type dopant within the conductively-doped semiconductor material that is different from the first dopant, the second dopant being present at an atomic concentration within the semiconductor material of at least 0.1%.

5. The elevationally-extending string of memory cells of claim 4 comprising (a).

6. The elevationally-extending string of memory cells of claim 5 wherein the conductive material is directly against the conductively-doped semiconductor material.

7. The elevationally-extending string of memory cells of claim 5 wherein the conductive material is not another conductively-doped semiconductor material.

8. The elevationally-extending string of memory cells of claim 7 wherein the conductive material is metal material.

9. The elevationally-extending string of memory cells of claim 5 wherein the conductive material extends elevationally upward along sidewalls of the conductively-doped semiconductor material.

10. The elevationally-extending string of memory cells of claim 5 wherein the conductive material does not extend elevationally upward along sidewalls of the conductively-doped semiconductor material.

11. The elevationally-extending string of memory cells of claim 5 wherein the conductive material comprises at least one of Ti, TiN, W, WN, WSi x , TiSi, Ti x Si y N z , and W x Si y N z .

12. The elevationally-extending string of memory cells of claim 5 wherein the conductive material comprises a non-stoichiometric metal-rich amorphous compound.

13. The elevationally-extending string of memory cells of claim 4 comprising (b).

14. The elevationally-extending string of memory cells of claim 13 wherein the second non-p-type dopant is not electrically active.

15. The elevationally-extending string of memory cells of claim 13 wherein the second non-p-type dopant is electrically active and n-type.

16. An elevationally-extending string of memory cells individually comprising a programmable charge storage transistor, comprising:

an upper stack elevationally over a lower stack, the upper and lower stacks individually comprising vertically-alternating tiers comprising control gate material of individual charge storage field effect transistors vertically alternating with insulating material;

an upper stack p-type channel pillar extending through multiple of the vertically-alternating tiers in the upper stack and a lower stack p-type channel pillar extending through multiple of the vertically-alternating tiers in the lower stack; tunnel insulator, charge storage material, and control gate blocking insulator being laterally between the respective upper and lower stack p-type channel pillars and the control gate material;

a conductive interconnect comprising conductively-doped n-type semiconductor material elevationally between and electrically coupling the upper and lower stack p-type channel pillars together, the conductively-doped n-type semiconductor material comprising a first n-type conductivity-producing dopant; and

an upper region of the lower stack p-type channel pillar comprising a second non-p-type dopant that is different from the first n-type dopant, the second dopant being present in the upper region of the lower stack p-type channel pillar at an atomic concentration in the upper region of at least 0.1%.

17. An elevationally-extending string of memory cells individually comprising a programmable charge storage transistor, comprising:

an upper stack elevationally over a lower stack, the upper and lower stacks individually comprising vertically-alternating tiers comprising control gate material of individual charge storage field effect transistors vertically alternating with insulating material;

an upper stack channel pillar extending through multiple of the vertically-alternating tiers in the upper stack and a lower stack channel pillar extending through multiple of the vertically-alternating tiers in the lower stack; tunnel insulator, charge storage material, and control gate blocking insulator being laterally between the respective upper and lower stack channel pillars and the control gate material; the upper and lower channel pillars comprising a channel conductivity-modifying dopant in a quantity that produces intrinsic semiconductor properties enabling the upper and lower channel pillars to operably function as switchable “on” and “off” channels for the individual memory cells for control gate voltage above and below, respectively, a V t depending on programming state of the charge storage transistor for the respective individual memory cell;

a conductive interconnect comprising conductively-doped semiconductor material elevationally between and electrically coupling the upper and lower stack channel pillars together, the conductively-doped semiconductor material comprising a first conductivity-producing dopant; and

an upper region of the lower stack channel pillar comprising a second non-p-type dopant that is different from the first dopant and is different from the channel conductivity-modifying dopant, the second dopant being present in the upper region of the lower stack channel pillar at an atomic concentration in the upper region of at least 0.1%.

18. The elevationally-extending string of memory cells of claim 1 wherein the diffusion barrier is not anywhere within the conductive interconnect.

19. The elevationally-extending string of memory cells of claim 1 wherein the diffusion barrier is within an upper region of the lower stack channel pillar.

20. The elevationally-extending string of memory cells of claim 5 being devoid of (b).

21. The elevationally-extending string of memory cells of claim 13 wherein the second non-p-type dopant is at least one of C, N, and As.

22. The elevationally-extending string of memory cells of claim 13 wherein atomic concentration of all of the second non-p-type dopant present within the conductively-doped semiconductor material is no greater than 40%.

23. The elevationally-extending string of memory cells of claim 13 wherein atomic concentration of all of the second non-p-type dopant present within the conductively-doped semiconductor material is no greater than 8%.

24. The elevationally-extending string of memory cells of claim 13 wherein atomic concentration of all of the second non-p-type dopant present within the conductively-doped semiconductor material is no greater than 2%.

25. The elevationally-extending string of memory cells of claim 13 wherein the conductive interconnect has an elevationally innermost surface, the region extending elevationally inward to said innermost surface.

26. The elevationally-extending string of memory cells of claim 25 wherein the second non-p-type dopant is within an elevationally outermost region of the lower stack channel pillar.

27. The elevationally-extending string of memory cells of claim 13 wherein the conductive interconnect has an elevationally innermost surface, the region not extending elevationally inward to said innermost surface.

28. The elevationally-extending string of memory cells of claim 13 being devoid of (a).

29. The elevationally-extending string of memory cells of claim 16 wherein the second non-p-type dopant is not electrically active.

30. The elevationally-extending string of memory cells of claim 16 wherein the lower stack channel pillar has an elevationally outermost surface, the region extending elevationally outward to said outermost surface.

31. The elevationally-extending string of memory cells of claim 16 wherein the lower stack channel pillar has an elevationally outermost surface, the region not extending elevationally outward to said outermost surface.