Through array contact (TAC) for three-dimensional memory devices

Patent metadata

Field	Value
Publication number	US-10658378-B2
Application number	US-201816047182-A
Country	US
Kind code	B2
Filing date	Jul 27, 2018
Priority date	May 3, 2018
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

Embodiments of interconnect structures of a three-dimensional (3D) memory device and method for forming the interconnect structures are disclosed. In an example, a 3D NAND memory device includes a semiconductor substrate, an alternating layer stack disposed on the semiconductor substrate, and a dielectric structure, which extends vertically through the alternating layer stack, on an isolation region of the substrate. Further, the alternating layer stack abuts a sidewall surface of the dielectric structure and the dielectric structure is formed of a dielectric material. The 3D memory device additionally includes one or more through array contacts that extend vertically through the dielectric structure and the isolation region, and one or more channel structures that extend vertically through the alternating layer stack.

First claim

What is claimed is:

1. A three-dimensional (3D) memory device, comprising:
a semiconductor substrate;
an alternating layer stack disposed on the semiconductor substrate;
a dielectric structure on an isolation region of the substrate and extending vertically through the alternating layer stack, wherein the alternating layer stack abuts a sidewall surface of the dielectric structure and the dielectric structure is formed of a dielectric material;
one or more through array contacts (TACs) extending vertically through the dielectric structure and the isolation region;
one or more channel structures extending vertically through the alternating layer stack;
an epitaxial layer between the one or more channel structures and the semiconductor substrate;
an etch stop plug on each of the one or more channel structures;
a staircase structure in the alternating layer;
slit structures extending vertically in the alternating layer stack; and
one or more contact layers on the one or more TACs, the one or more channel structures, and the slit structures.

2. The 3D memory device of claim 1 , wherein the dielectric structure abuts a sidewall surface of the TACs.

3. The 3D memory device claim 1 , wherein the 3D memory device is a NAND 3D memory device.

4. The 3D memory device of claim 1 , wherein the alternating layer stack comprises alternating pairs of a dielectric and a conductor layer.

5. The 3D memory device of claim 1 , wherein the dielectric material is silicon oxide.

6. The 3D memory device of claim 1 , wherein the dielectric structure comprises an oxide.

7. The 3D memory device of claim 1 , wherein the dielectric structure defines a through array contact region within the 3D memory device.

8. The 3D memory device of claim 1 , wherein the dielectric structure has a footprint equal to or smaller than the isolation region.

9. A method for forming a 3D memory device, the method comprising:
forming an isolation structure on a substrate;
disposing an alternating dielectric layer stack on the substrate, the alternating dielectric layer stack comprising pairs of a first dielectric layer and a second dielectric layer different from the first dielectric layer;
disposing a staircase structure in the alternating dielectric layer stack, wherein the staircase structure comprises levels with each level having a conductor layer thereon;
forming a channel structure extending vertically in the alternating dielectric layer stack;
disposing a word line contact on the conductor layer of the each level of the staircase structure;
forming one or more slit structures extending vertically in the alternating dielectric layer stack;
forming an opening in the alternating dielectric layer stack, wherein the opening exposes the isolation structure;
filling the opening with a dielectric layer to form a dielectric structure as a through array contact (TAC) region of the 3D memory device;
removing portions of the dielectric structure and the isolation structure until the substrate is exposed to form a TAC opening that vertically extends through the dielectric structure and the isolation structure;
filling the TAC opening with a conductor to form a TAC structure in the TAC region, wherein the TAC structure is in contact with the substrate; and
disposing a local contact on the channel structure, the one or more slit structures, and the TAC structure.

10. The method of claim 9 , wherein the forming one or more slit structures comprises;
forming slit openings extending vertically in the alternating dielectric layer stack, wherein the slit openings expose a doped region of the substrate;
replacing the second dielectric layer through the one or more slit openings with the conductor layer to convert the alternating dielectric layer stack to an alternating dielectric/conductor layer stack; and
filling the one or more slit openings with a conductor.

11. The method of claim 9 , wherein the disposing the staircase structure comprises performing a trim-etch process in the alternating dielectric layer stack before forming the channel structure.

12. The method of claim 9 , wherein filling the opening with the dielectric layer comprises depositing the dielectric layer with a chemical vapor deposition, a plasma-enhanced chemical vapor deposition, or a physical vapor deposition process.

13. The method of claim 9 , wherein filling the opening with the dielectric layer comprises forming an oxide.

14. The method of claim 9 , wherein the first dielectric layer comprises an oxide and the second dielectric layer comprises a nitride.

15. A three-dimensional (3D) memory device, comprising:
a substrate with an isolation structure;
an alternating conductor/dielectric layer stack disposed on the substrate;
a dielectric structure on the isolation structure and extending vertically through the alternating conductor/dielectric layer stack, wherein the alternating conductor/dielectric layer stack abuts a sidewall surface of the dielectric structure and the dielectric structure is formed of a dielectric material;
channel structures and slit structures extending vertically through the alternating conductor/dielectric layer stack;
a staircase structure disposed in the alternating conductor/dielectric layer stack, wherein the staircase structure comprises levels with each level having a conductor layer thereon;
a word line contact disposed on the conductor layer of the each level;
local contacts disposed on the channel structures and the slit structures; and
through array contacts (TACs) extending vertically through the dielectric and the isolation structures.

16. The 3D memory device of claim 15 , wherein the dielectric structure abuts a sidewall of each TAC of the TACs.

17. The 3D memory device of claim 15 , wherein the dielectric structure comprises a through array contact region of the 3D memory device.

18. The 3D memory device of claim 15 , further comprising:
an etch stop plug interposed between each local contact of the local contacts and each channel structure of the channel structures; and
an epitaxial layer disposed between the channel structures and the substrate.

19. The 3D memory device of claim 15 , wherein the dielectric material comprises silicon oxide.

20. The 3D memory device of claim 15 , wherein the TACs comprise a conductive material.

Assignees

• Yangtze Memory Tech Co Ltd

Inventors

• Tao Qian
• Hu Yushi
• Lu Zhenyu
• Xiao li hong
• Dai Xiaowang
• Zhou yu ting
• Tang Zhao Hui
• Guo mei lan
• Tang Zhiwu
• Wei Qinxiang
• Xu Qianbing
• Liu Sha Sha
• Sun Jian Hua
• Wang Enbo

Classifications

• H01L21/76831

  Electricity · mapped topic

• H01L27/1157

  Electricity · mapped topic

• H01L21/76877

  Electricity · mapped topic

• H01L27/11582 Primary

  Electricity · mapped topic

• H01L21/76802

  Electricity · mapped topic