Three-dimensional memory device and methods of making the same using replacement drain select gate electrodes

1. A three-dimensional memory device, comprising:

an alternating stack of insulating layers and electrically conductive layers located over a substrate;

drain-select-level electrically conductive strips located over the alternating stack;

a drain-select-level isolation structure located between a neighboring pair of the drain-select-level electrically conductive strips;

memory stack structures comprising a respective memory film and a respective vertical semiconductor channel vertically extending through the alternating stack and a respective one of the drain-select-level electrically conductive strips, wherein the memory stack structures contact, and are completely laterally surrounded by, a cylindrical sidewall of a respective one of the drain-select-level electrically conductive strips;

a contact level dielectric layer overlying the drain-select-level electrically conductive strips, the drain-select-level isolation structure and the memory stack structures, wherein the contact level dielectric layer contacts the drain-select-level isolation structure; and

at least one feature selected from:

(i) a first feature further comprising drain regions located at a top end of a respective one of the memory stack structures,

wherein:

a bottom periphery of each of the drain regions coincides with a topmost periphery of an outer sidewall of an underlying one of the memory stack structures; and

sidewalls of the drain-select-level electrically conductive strips are in contact with sidewalls of the memory stack structures, and are vertically coincident with sidewalls of the drain regions; or

(ii) a second feature wherein each of the drain-select-level electrically conductive strips has a respective laterally alternating sequence of planar vertical sidewall segments and convex vertical sidewall segments, wherein each convex vertical sidewall segment is laterally spaced from a most proximal one of the memory stack structures by a uniform lateral spacing; or

(iii) a third feature wherein each of the drain-select-level electrically conductive strips has a top surface located below a horizontal plane including a top surface of the drain-select-level isolation structure; and each of the drain-select-level electrically conductive strips has a bottom surface located within a horizontal plane including a bottom surface of the drain-select-level isolation structure; or

(iv) a fourth feature wherein:

the memory stack structures are arranged as rows that laterally extend with a uniform pitch along a first horizontal direction; and

the three-dimensional memory device further comprises an insulating cap strip located over the alternating stack and having a straight sidewall that extend along the first horizontal direction by at least twice the uniform pitch; or

(v) a fifth feature wherein:

the drain-select-level isolation structure generally extends along a first horizontal direction; and

the drain-select-level isolation structure includes a pair of laterally alternating sequences of planar vertical sidewall segments and concave vertical sidewall segments that alternate along the first horizontal direction.

2. The three-dimensional memory device of claim 1 , wherein the three-dimensional memory device comprises the first feature.

3. The three-dimensional memory device of claim 1 , wherein the three-dimensional memory device comprises the second feature.

4. The three-dimensional memory device of claim 1 , wherein the three-dimensional memory device comprises the third feature.

5. The three-dimensional memory device of claim 1 , wherein the three-dimensional memory device comprises the fourth feature.

6. The three-dimensional memory device of claim 1 , wherein the three-dimensional memory device comprises the fifth feature.

7. The three-dimensional memory device of claim 6 , wherein each of the concave vertical sidewall segments is laterally spaced from a respective most proximal one of the memory stack structures by a uniform lateral spacing.

8. The three-dimensional memory device of claim 7 , wherein the uniform lateral spacing is the same as a lateral width of peripheral portions of the drain-select-level electrically conductive strips disposed between the drain-select-level isolation structure and most proximal ones among the memory stack structures.

9. A three-dimensional memory device, comprising:

an alternating stack of insulating layers and electrically conductive layers located over a substrate;

drain-select-level electrically conductive strips located over the alternating stack;

a drain-select-level isolation structure located between a neighboring pair of the drain-select-level electrically conductive strips;

memory stack structures comprising a respective memory film and a respective vertical semiconductor channel vertically extending through the alternating stack and a respective one of the drain-select-level electrically conductive strips, wherein the memory stack structures contact, and are completely laterally surrounded by, a cylindrical sidewall of a respective one of the drain-select-level electrically conductive strips; and

a contact level dielectric layer overlying the drain-select-level electrically conductive strips, the drain-select-level isolation structure and the memory stack structures, wherein the contact level dielectric layer contacts the drain-select-level isolation structure,

wherein:

each of the drain-select-level electrically conductive strips comprises a respective metallic nitride liner and a respective metallic fill material portion;

each metallic nitride liner consists essentially of a conductive metal nitride; and

each metal fill material portion consists essentially of an elemental metal or an intermetallic alloy.

10. A three-dimensional memory device, comprising:

an alternating stack of insulating layers and electrically conductive layers located over a substrate;

drain-select-level electrically conductive strips located over the alternating stack;

a drain-select-level isolation structure located between a neighboring pair of the drain-select-level electrically conductive strips;

memory stack structures comprising a respective memory film and a respective vertical semiconductor channel vertically extending through the alternating stack and a respective one of the drain-select-level electrically conductive strips, wherein the memory stack structures contact, and are completely laterally surrounded by, a cylindrical sidewall of a respective one of the drain-select-level electrically conductive strips;

a contact level dielectric layer overlying the drain-select-level electrically conductive strips, the drain-select-level isolation structure and the memory stack structures, wherein the contact level dielectric layer contacts the drain-select-level isolation structure;

dielectric cores embedded within a respective one of the vertical semiconductor channels and including a respective upper cylindrical portion embedded within the drain-select-level electrically conductive strips; and

core cavities embedded within a respective one of the dielectric cores and having a maximum lateral dimension that is greater than a maximum lateral dimension of an overlying one of the upper cylindrical portions of the dielectric cores.