Three-dimensional memory device containing plural work function word lines and methods of forming the same

Patent metadata

Field	Value
Publication number	US-11063063-B2
Application number	US-201916710481-A
Country	US
Kind code	B2
Filing date	Dec 11, 2019
Priority date	Dec 11, 2019
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

A three-dimensional memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, memory openings vertically extending through the alternating stack, and memory stack structures extending through the alternating stack. Each of the memory stack structures contains a memory film and a vertical semiconductor channel. At least one of the electrically conductive layers contains a first conductive material portion having a respective inner sidewall that contacts a respective one of the memory films at a vertical interface, and a second conductive material portion that has a different composition from the first conductive material portion, and contacting the first electrically conductive material portion. The first conductive material portion has a lower work function than the second conductive material portion.

First claim

What is claimed is:

1. A three-dimensional memory device comprising:
an alternating stack of insulating layers and electrically conductive layers located over a substrate;
memory openings vertically extending through the alternating stack; and
memory stack structures extending through the alternating stack,

wherein:
each of the memory stack structures comprises a memory film and a vertical semiconductor channel; and
at least one of the electrically conductive layers comprises:
a first conductive material portion having a respective inner sidewall that contacts a respective one of the memory films at a vertical interface; and
a second conductive material portion that has a different composition from the first conductive material portion, and contacting the first electrically conductive material portion, a bottom surface of a first one of the insulating layers and a top surface of a second one of the insulating layers, wherein the first conductive material portion has a lower work function than the second conductive material portion.

2. The three-dimensional memory device of claim 1 , wherein the second conductive material portion laterally surrounds the first conductive material portion.

3. The three-dimensional memory device of claim 1 , wherein the first conductive material portion has a respective upper annular surface that contacts the bottom surface of the first one of the insulating layers, and a respective lower annular surface that contacts the top surface of the second one of the insulating layers.

4. The three-dimensional memory device of claim 1 , wherein the inner sidewall of the first conductive material portion is vertically coincident with interface between the memory film and the insulating layers.

5. The three-dimensional memory device of claim 1 , wherein the first conductive material portion has a respective outer sidewall that is laterally offset from the respective inner sidewall by a thickness of the first conductive material portion.

6. The three-dimensional memory device of claim 1 , wherein the thickness of the first conductive material portion is in a range from 0.5 nm to 15 nm.

7. The three-dimensional memory device of claim 1 , wherein:
the first conductive material portion comprises ruthenium; and
the second conductive material portion comprises a metallic nitride, tungsten, or cobalt.

8. The three-dimensional memory device of claim 7 , wherein the second conductive material portion comprises titanium nitride.

9. The three-dimensional memory device of claim 1 , wherein:
the first conductive material portion comprises n-type polysilicon; and
the second conductive material portion comprises a metallic nitride, tungsten, or cobalt.

10. The three-dimensional memory device of claim 9 , wherein the second conductive material portion comprises titanium nitride.

11. The three-dimensional memory device of claim 10 , wherein:
the first conductive material portion has a tubular configuration;
an entirety of an outer cylindrical sidewall of the first conductive material portion is in contact with an inner sidewall of the second conductive material portion; and
the second conductive material portion comprises:
tubular portion that laterally surrounds the first conductive material portion;
an upper horizontally extending portion adjoined to an upper end of the tubular portion; and
a lower horizontally extending portion adjoined to a lower end the tubular portion.

12. The three-dimensional memory device of claim 11 , wherein each of the tubular portion, the upper horizontally extending portion, and the lower horizontally extending portion contacts a tungsten portion.

13. The three-dimensional memory device of claim 9 , wherein the second conductive material portion comprises cobalt.

14. The three-dimensional memory device of claim 13 , further comprising a backside trench fill structure contacting sidewalls of the alternating stack, wherein the second conductive material portion does not contact the backside trench fill structure, and is laterally spaced from the backside trench fill structure by a third conductive material portion having a composition that is different from the second conductive material portion.

15. The three-dimensional memory device of claim 14 , wherein the third conductive material portion comprises at least one of tungsten or conductive metallic nitride.

Assignees

• Sandisk Technologies Llc

Inventors

• Zhang Yanli
• Moon Dong-Il
• Makala Raghuveer S
• Zhang Peng
• Zhao Wei
• Baraskar Ashish

Classifications

• H10P50/283

  by chemical means · CPC title

• H10W20/4451

  Semiconductor materials, e.g. polysilicon · CPC title

• H10W20/4441

  the principal metal being a refractory metal · CPC title

• H10W20/4432

  the principal metal being a noble metal, e.g. gold · CPC title

• H10W20/43

  Layouts of interconnections · CPC title