High aspect ratio via fill process employing selective metal deposition and structures formed by the same
A metal interconnect assembly includes a first metal interconnect structure, and a second metal interconnect structure embedded in a second dielectric material layer and containing a metal line portion having a top surface located within a first horizontal plane and having a bottom surface located within a second horizontal plane, and further containing a metal via portion adjoined to a bottom of the metal line portion and contacting a top surface of the first metal interconnect structure. The second metal interconnect structure contains a metallic liner including a first metallic material that includes an entire volume of the metal via portion and an outer part of the metal line portion, and a metallic fill material portion contains a second metallic material that includes an inner part of the metal line portion, does not contact and is spaced from the second dielectric material layer by the metallic liner.
1 . A metal interconnect assembly, comprising:
a first metal interconnect structure embedded in a first dielectric material layer; and
a second metal interconnect structure embedded in a second dielectric material layer and comprising a metal line portion having a top surface located within a first horizontal plane and having a bottom surface located within a second horizontal plane, and further comprising a metal via portion adjoined to a bottom of the metal line portion and contacting a top surface of the first metal interconnect structure,
wherein the second metal interconnect structure comprises a metallic liner comprising a first metallic material that comprises an entire volume of the metal via portion and an outer part of the metal line portion and in direct contact with a dielectric sidewall of the second dielectric material layer, and a metallic fill material portion comprising a second metallic material that comprises an inner part of the metal line portion, does not contact the second dielectric material layer and is spaced from the second dielectric material layer by the metallic liner.
2 . The metal interconnect assembly of claim 1 , wherein the first metallic material comprises a metal selected from ruthenium, tungsten, molybdenum, or cobalt, and the metal selected from the ruthenium, tungsten, molybdenum, or cobalt directly contacts the dielectric sidewall of the second dielectric material layer and directly contacts the second metallic material.
3 . The metal interconnect assembly of claim 2 , wherein the first metallic material comprises the metal at an atomic percentage greater than 98%.
4 . The metal interconnect assembly of claim 1 , wherein the first metallic material consists essentially of ruthenium.
5 . The metal interconnect assembly of claim 1 , wherein a vertical thickness of a horizontally-extending portion of the metallic liner overlying the second horizontal plane is less than a height of the metal via portion.
6 . The metal interconnect assembly of claim 5 , wherein a vertically-extending portion of the metallic liner located on the dielectric sidewall of the second dielectric material layer has a same thickness as the vertical thickness of the horizontally-extending portion of the metallic liner.
7 . The metal interconnect assembly of claim 5 , wherein:
the metal via portion has a sidewall vertically extending between the metal line portion and the first metal interconnect structure; and
a minimum lateral distance between opposing line segments of a bottom periphery of the sidewall that have parallel tangent lines is greater than twice the vertical thickness of the horizontally-extending portion of the metallic liner.
8 . The metal interconnect assembly of claim 1 , wherein the metal via portion is free of any seam therein.
9 . The metal interconnect assembly of claim 1 , wherein an entirety of an interface between the metallic liner and the metallic fill material is located above the second horizontal plane.
10 . The metal interconnect assembly of claim 9 , wherein the interface between the metallic liner and the metallic fill material portion comprises:
a first horizontal interface segment having an areal overlap with an interface between the metal via portion and the first metal interconnect structure in a view along a vertical direction; and
a second horizontal interface segment having an areal overlap with an interface between the metal line portion and the second dielectric material layer in the view along the vertical direction.
11 . The metal interconnect assembly of claim 10 , wherein the first horizontal interface segment is located above a horizontal plane including the second horizontal interface segment.
12 . The metal interconnect assembly of claim 10 , wherein the first horizontal interface segment is located below a horizontal plane including the second horizontal interface segment.
13 . The metal interconnect assembly of claim 1 , wherein:
the metallic fill material portion comprises copper;
a bottom surface of the metal via portion contacts a copper surface of the first metal interconnect structure; and
the first metallic material of the metallic liner is in direct contact with a dielectric material of the second dielectric material layer.
14 . A semiconductor structure, comprising:
the metal interconnect assembly of claim 1 ; and
a three dimensional memory device comprising:
an alternating stack of insulating layers and electrically conductive layers; and
a memory opening fill structure extending through the alternating stack and comprising a vertical semiconductor channel, a memory film surrounding the vertical semiconductor channel, and a drain region contacting a top end of the vertical semiconductor channel, wherein the first metal interconnect structure comprises a copper bit line which is electrically connected to the drain region.
15 . A method of forming a device structure, comprising:
forming semiconductor devices over a substrate;
forming a first metal interconnect structure embedded in a first dielectric material layer over the semiconductor devices;
forming a second dielectric material layer over the first metal interconnect structure and the first dielectric material layer;
forming an integrated line-and-via cavity in the second dielectric material layer, wherein the integrated line-and-via cavity comprises a via cavity that overlies a physically exposed surface of the first metal interconnect structure and a line cavity adjoined to an upper portion of the via cavity;
depositing a first metallic material by performing an area selective deposition process, wherein the first metallic material nucleates and grows from the physically exposed surface of the first metal interconnect structure prior to nucleation on and growth from the second dielectric material layer, wherein an entire volume of the via cavity is filled with the first metallic material to form a metallic liner such that the first metallic material is in direct contact with a dielectric sidewall of the second dielectric material layer around the via cavity;
depositing a second metallic material in an unfilled volume of the integrated line-and-via cavity on a physically exposed surface of the metallic liner; and
removing portions of the second metallic material and the first metallic material from above the horizontal plane including a top surface of the second dielectric material layer by performing a planarization process, wherein a second metal interconnect structure is formed, which comprises a metallic liner including a remaining portion of the first metallic material and a metallic fill material portion including a remaining portion of the second metallic material.
16 . The method of claim 15 , further comprising selectively forming an organic growth suppressor material layer on surfaces of the second dielectric material layer while leaving the physically exposed surface of the first metal interconnect structure at a bottom of the via cavity.
17 . The method of claim 16 , wherein the area selective deposition process grows an initial first metallic material portion from the physically exposed surface of the first metal interconnect structure while more than 50% of the organic growth suppressor material layer covered surfaces of the second dielectric material layer are not covered by any portion of the first metallic material.
18 . The method of claim 17 , wherein the metallic liner completely fills the via cavity and only partially fills the line cavity.
19 . The method of claim 16 , wherein the first metallic material comprises a metal selected from ruthenium, tungsten, molybdenum, or cobalt, and the second metallic material comprises copper, and the metal selected from the ruthenium, tungsten, molybdenum, or cobalt directly contacts the dielectric sidewall of the second dielectric material layer and directly contacts the second metallic material comprising the copper.
20 . The method of claim 19 , wherein the first metallic material consists essentially of ruthenium.