Multiheight contact via structures for a multilevel interconnect structure

Patent metadata

Field	Value
Publication number	US-2016307912-A1
Application number	US-201615189458-A
Country	US
Kind code	A1
Filing date	Jun 22, 2016
Priority date	Aug 26, 2014
Publication date	Oct 20, 2016
Grant date	—

Abstract

Contact openings extending to sacrificial layers located at different depths can be formed by sequentially exposing a greater number of openings in a mask layer by iterative alternation of trimming of a slimming layer over the mask layer and an anisotropic etch that recesses pre-existing contact openings by one level. In one embodiment, pairs of an electrically conductive via contact and electrically conductive electrodes can be simultaneously formed as integrated line and via structures. In another embodiment, encapsulated unfilled cavities can be formed in the contact openings by non-conformal deposition of a material layer, electrically conductive electrodes can be formed by replacement of portions of the sacrificial layers, and the electrically conductive via contacts can be subsequently formed on the electrically conductive electrodes. Electrically conductive via contacts extending to electrically conductive electrodes located at different level can be provided with self-aligned insulating liner.

First claim

What is claimed is:

1 . A method of making multi-level contacts, comprising:
providing an in-process multilevel device comprising a device region and a contact region comprising a stack of plurality of alternating sacrificial layers and insulating layers located over a major surface of a substrate; forming a plurality of contact openings extending substantially perpendicular to the major surface of the substrate to the plurality of sacrificial layers, wherein each of the plurality of contact openings extends through the stack to a respective one of the sacrificial layers; selectively removing the sacrificial layers from the stack to form a plurality of recesses extending substantially parallel to the major surface of the substrate between the insulating layers; and depositing a plurality of electrically conductive via contacts in the plurality of the contact openings and a plurality of electrically conductive electrodes in the plurality of recesses in one deposition step.

2 . The method of claim 1 , wherein the step of forming the plurality of contact openings comprises:
forming a mask with a plurality of openings over the stack; forming a slimming layer over the mask; etching the slimming layer to reduce its thickness and width to expose a first opening in the mask; etching a portion of a first insulating layer exposed in the first opening to form a portion of a first contact opening in the first insulating layer extending to a first sacrificial layer located under the first insulating layer in the stack; etching the slimming layer to reduce its thickness and width to expose a second opening in the mask; and etching a portion of the first insulating layer exposed in the second opening to form a portion of a second contact opening in the first insulating layer extending to the first sacrificial layer, and etching a portion of the first sacrificial layer and a portion of a second insulating layer through the first contact opening to extend the first contact opening to a second sacrificial layer located under the second insulating layer in the stack.

3 . The method of claim 2 , wherein etching a portion of the first insulating layer and etching a portion of the first sacrificial layer and a portion of the second insulating layer occur in a same etching step.

4 . The method of claim 3 , wherein the step of forming the plurality of contact openings further comprises:
etching the slimming layer to reduce its thickness and width to expose a third opening in the mask; and etching a portion of the first insulating layer exposed in the third opening to form a portion of a third contact opening in the first insulating layer extending to the first sacrificial layer, etching a portion of the first sacrificial layer and a portion of the second insulating layer through the second contact opening to extend the second contact opening to a second sacrificial layer located under the second insulating layer in the stack, and etching a portion of the second sacrificial layer and a portion of a third insulating layer through the first contact opening to extend the first contact opening to a third sacrificial layer located under the third insulating layer in the stack.

5 . The method of claim 4 , wherein etching a portion of the first insulating layer, and etching a portion of the first sacrificial layer and a portion of the second insulating layer, and etching a portion of the second sacrificial layer and a portion of the third insulating layer occur in a same etching step.

6 . The method of claim 5 , wherein the step of forming the plurality of contact openings further comprises continuing to etch the slimming layer until all of the plurality of openings in the mask are exposed and a respective one of the plurality of contact openings is etched through each opening in the mask to a respective one of the plurality of sacrificial layers.

7 . The method of claim 2 , further comprising forming an insulating liner on a sidewall of each of the plurality of contact openings.

8 . The method of claim 7 , wherein forming the insulating liner comprises depositing an insulating material on the sidewall and bottom surface of each of the plurality of contact openings and removing the insulating material from the bottom surface of each of the plurality of contact openings.

9 . The method of claim 7 , wherein:
the sacrificial layers comprise at least a first sacrificial layer in a first device level located over the major surface of the substrate and a second sacrificial layer in a second device level located lower than the first device level over the major surface of the substrate; and the first contact opening extends to an upper surface of the second sacrificial layer;
the second contact opening extends to an upper surface of the first sacrificial layer; and
the first sacrificial layer extends around the first contact opening.

10 . The method of claim 9 , further comprising forming a trench through the stack, wherein selectively removing the sacrificial layers from the stack comprises selectively removing the sacrificial layers through the plurality of openings and through the trench to form the plurality of recesses.

11 . The method of claim 10 , wherein:
selectively removing the sacrificial layers from the stack comprises selectively removing the first sacrificial layer to form a first recess located between the first and the second insulating layers, and selectively removing the second sacrificial layer to form a second recess located between the second and the third insulating layers; depositing the plurality of electrically conductive via contacts in the plurality of the contact openings comprises depositing a first electrically conductive via contact in the first contact opening and depositing a second electrically conductive via contact in the second contact opening in a same deposition step; depositing the plurality of electrically conductive electrodes in the plurality of recesses comprises depositing a first electrically conductive electrode into the first recess through at least one of the trench and the first contact opening, and depositing a second electrically conductive electrode into the second recess through at least one of the trench and the second contact opening in the same deposition step as depositing the first and the second electrically conductive via contacts; the first electrically conductive electrode extends around the first contact opening and the first electrically conductive via contact is located in the first contact opening;
wherein the insulating liner on the sidewall of the first contact opening electrically isolates the second electrically conductive electrode from the first electrically conductive via contact located in the first contact opening; and
the first electrically conductive via contact extends deeper than the second electrically conductive via contact such that bottom surfaces of the plurality of electrically conductive via contacts form a step pattern.

12 . The method of claim 11 , further comprising removing an electrically conductive electrode material of the plurality of electrically conductive electrodes from the trench, forming an insulating layer on a sidewall of the trench, and forming a source line in the trench such that the source line electrically contacts a portion of the device region of the device.

13 . The method of claim 11 , wherein:
forming the plurality of contact openings comprises forming a linear set of first contact openings which extend to the upper surface of the second conductive layer and forming a linear set of second contact openings which extend to t

Assignees

• Sandisk Technologies Llc

Inventors

• Izumi Keisuke
• Iuchi Hiroaki
• Taura Ryo
• Sera Kentaro
• Yanai Akio

Classifications

• H10P50/283

  by chemical means · CPC title

• H10P50/73

  using masks for insulating materials · CPC title

• H10W20/089 Primary

  using processes for implementing desired shapes or dispositions of the openings, e.g. double patterning · CPC title

• H10W20/083

  the openings being via holes penetrating underlying conductors · CPC title

• H10W20/076

  in via holes or trenches · CPC title