Source structure of three-dimensional memory device and method for forming the same

Patent metadata

Field	Value
Publication number	US-10147732-B1
Application number	US-201815934738-A
Country	US
Kind code	B1
Filing date	Mar 23, 2018
Priority date	Nov 30, 2017
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

Embodiments of source structure of a three-dimensional (3D) memory device and method for forming the source structure of the 3D memory device are disclosed. In an example, a NAND memory device includes a substrate, an alternating conductor/dielectric stack, a NAND string, a source conductor layer, and a source contact. The alternating conductor/dielectric stack includes a plurality of conductor/dielectric pairs above the substrate. The NAND string extends vertically through the alternating conductor/dielectric stack. The source conductor layer is above the alternating conductor/dielectric stack and is in contact with an end of the NAND string. The source contact includes an end in contact with the source conductor layer. The NAND string is electrically connected to the source contact by the source conductor layer. In some embodiments, the source conductor layer includes one or more conduction regions each including one or more of a metal, a metal alloy, and a metal silicide.

First claim

What is claimed is:

1. A NAND memory device, comprising:
a substrate;
an alternating conductor/dielectric stack comprising a plurality of conductor/dielectric pairs above the substrate;
a NAND string extending vertically through the alternating conductor/dielectric stack;
a source conductor layer above the alternating conductor/dielectric stack and in physical contact with a first end of the NAND string; and
a source contact comprising a first end in physical contact with the source conductor layer, wherein the NAND string is electrically connected to the source contact by the source conductor layer.

2. The NAND memory device of claim 1 , wherein the source conductor layer comprises one or more conduction regions each comprising one or more of a metal, a metal alloy, and a metal silicide.

3. The NAND memory device of claim 2 , wherein the metal comprises one or more of copper, cobalt, nickel, titanium, and tungsten.

4. The NAND memory device of claim 2 , wherein the metal alloy comprises an alloy of at least two of copper, cobalt, nickel, titanium, and tungsten.

5. The NAND memory device of claim 2 , wherein the metal silicide comprises one or more of copper silicide, cobalt silicide, nickel silicide, titanium silicide, and tungsten silicide.

6. The NAND memory device of claim 1 , further comprising an epitaxial silicon layer between the NAND string and the source conductor layer, wherein the NAND string is electrically connected to the source conductor layer by the epitaxial silicon layer.

7. The NAND memory device of claim 1 , wherein:
the source conductor layer comprises a plurality of conduction regions and one or more isolation regions electrically isolating the plurality of conduction regions; and
the NAND string is electrically connected to the source contact by a first conduction region of the plurality of conduction regions.

8. The NAND memory device of claim 7 , further comprising a through array contact (TAC) extending vertically through the alternating conductor/dielectric stack, wherein the TAC is in contact with a second conduction region of the plurality of conduction regions.

9. The NAND memory device of claim 8 , further comprising a first interconnect layer comprising a first contact, wherein the NAND string is electrically connected to the first contact by the first conduction region.

10. The NAND memory device of claim 9 , wherein the first interconnect layer further comprises a second contact and the TAC is electrically connected to the second contact by the second conduction region.

11. The NAND memory device of claim 10 , further comprising a peripheral device between the substrate and the NAND string.

12. The NAND memory device of claim 11 , further comprising a second interconnect layer above and in contact with the peripheral device, wherein the second interconnect layer comprises one or more conductor layers in one or more dielectric layers.

13. The NAND memory device of claim 12 , further comprising a third interconnect layer in contact with a second end of the NAND string and a second end of the source contact, wherein the third interconnect layer comprises one or more conductor layers in one or more dielectric layers.

14. The NAND memory device of claim 13 , further comprising a bonding interface between the second interconnect layer and the third interconnect layer, wherein the peripheral device is electrically connected to the NAND string by the second interconnect layer and the third interconnect layer.

15. A three-dimensional (3D) memory device, comprising:
a substrate;
a peripheral device on the substrate;
a plurality of memory strings each extending vertically above the peripheral device;
a source conductor layer above the plurality of memory strings, wherein an upper end of each of the plurality of memory strings is in physical contact with a first surface of the source conductor layer; and
a first interconnect layer on a second surface of the source conductor layer, the second surface being opposite to the first surface.

16. The 3D memory device of claim 15 , wherein the source conductor layer comprises a conduction region with an electrical conductivity of at least about 1×10 4 S/m at about 20° C.

17. The 3D memory device of claim 15 , wherein the source conductor layer comprises a conduction region comprising one or more of a metal, a metal alloy, and a metal silicide.

18. The 3D memory device of claim 15 , wherein each of the plurality of memory strings comprises an epitaxial plug at the upper end of the memory string.

19. The 3D memory device of claim 18 , wherein each of the plurality of memory strings comprises a select gate configured to control a conductance of a corresponding epitaxial plug.

20. The 3D memory device of claim 19 , wherein a conductance of the source conductor layer is independent from the select gate.

21. The 3D memory device of claim 15 , further comprising:
an alternating conductor/dielectric stack above the peripheral device, wherein each of the plurality of memory strings extends vertically through the alternating conductor/dielectric stack; and
a second interconnect layer between the peripheral device and the alternating conductor/dielectric stack.

Assignees

• Yangtze Memory Tech Co Ltd

Inventors

• Hu Yushi
• Lu Zhenyu
• Tao Qian
• Chen Jun
• Yang Simon Shi-Ning
• Yang Steve Weiyi

Classifications

• G11C16/04

  using variable threshold transistors, e.g. FAMOS · CPC title

• H01L27/11524 Primary

  Electricity · mapped topic

• H01L27/1157

  Electricity · mapped topic

• H10B43/40

  characterised by the peripheral circuit region · CPC title

• H10B43/27 Primary

  the channels comprising vertical portions, e.g. U-shaped channels · CPC title