High aspect ratio via fill process employing selective metal deposition and structures formed by the same
A method of forming a semiconductor structure includes forming a semiconductor device over a substrate, forming a combination of a connection-level dielectric layer and a connection-level metal interconnect structure over the semiconductor device, where the connection-level metal interconnect structure is electrically connected to a node of the semiconductor device and is embedded in the connection-level dielectric layer, forming a line-and-via-level dielectric layer over the connection-level dielectric layer, forming an integrated line-and-via cavity through the line-and-via-level dielectric layer over the connection-level metal interconnect structure, selectively growing a conductive via structure containing cobalt from a bottom of the via portion of the integrated line-and-via cavity without completely filling a line portion of the integrated line-and-via cavity, and forming a copper-based conductive line structure that contains copper at an atomic percentage that is greater than 90% in the line portion of the integrated line-and-via cavity on the conductive via structure.
1 . A method of forming a semiconductor structure, comprising:
forming a semiconductor device over a substrate;
forming a combination of a connection-level dielectric layer and a connection-level metal interconnect structure over the semiconductor device, wherein the connection-level metal interconnect structure is electrically connected to a node of the semiconductor device;
forming a single line-and-via-level dielectric layer over the connection-level dielectric layer;
forming an integrated line-and-via cavity comprising a line portion located over a via portion through the single line-and-via-level dielectric layer over the connection-level metal interconnect structure;
selectively growing a conductive via structure comprising cobalt from a bottom of the via portion of the integrated line-and-via cavity without completely filling the line portion of the integrated line-and-via cavity; and
forming a copper-based conductive line structure that comprises copper at an atomic percentage that is greater than 90% in the line portion of the integrated line-and-via cavity on the conductive via structure.
2 . The method of claim 1 , wherein an interconnect line-and-via structure comprising the conductive via structure and the copper-based conductive line structure is formed in the integrated line-and-via cavity.
3 . The method of claim 1 , further comprising:
forming a conductive liner layer in the integrated line-and-via cavity; and
forming a cobalt liner layer on the conductive liner layer.
4 . The method of claim 3 , wherein the conductive via structure and the copper-based conductive line structure are formed directly on the cobalt liner layer.
5 . The method of claim 4 , wherein the conductive via structure is formed by selectively growing a cobalt-based material comprising at least 90 atomic percent cobalt by electrochemical deposition from a physically exposed surface of the cobalt liner layer located at a bottom of the via portion of the integrated line-and-via cavity while suppressing growth of the cobalt-based material in the line portion of the integrated line-and-via cavity.
6 . The method of claim 5 , wherein the cobalt-based material consists essentially of cobalt, and the conductive liner layer comprises tantalum nitride.
7 . The method of claim 5 , further comprising forming a line cavity in the single line-and-via-level dielectric layer.
8 . The method of claim 7 , wherein:
the line cavity is shallower than the integrated line-and-via cavity;
the cobalt liner layer and the conductive liner layer are also formed in the line cavity and over a top surface of the single line-and-via-level dielectric layer; and
the conductive via structure is formed by selectively growing a cobalt-based material comprising at least 90 atomic percent cobalt by the electrochemical deposition from the physically exposed surface of the cobalt liner located at a bottom of the via portion of the integrated line-and-via cavity while suppressing growth of the of the cobalt-based material in the line portion of the integrated line-and-via cavity and in the line cavity.
9 . The method of claim 8 , further comprising:
non-selectively depositing a copper-based conductive material layer on the cobalt liner layer located in the line portion of the integrated line-and-via cavity, in the line cavity, and over a top surface of the single line-and-via-level dielectric layer, and on a top surface of the conductive via structure located in the via portion of the integrated line-and-via cavity; and
performing a chemical mechanical polishing to remove portions of the copper based-conductive material layer, the cobalt liner layer and the conductive liner layer from above the top surface of the single line-and-via-level dielectric layer to form the copper-based conductive line structure, a cobalt liner and a conductive liner in the line cavity and in the line portion of the integrated line-and-via cavity.
10 . The method of claim 9 , wherein chemical mechanical polishing forms a recess in a top surface of the copper-based conductive line structure by dishing.
11 . The method of claim 10 , further comprising forming a cobalt cap plate in the recess.
12 . The method of claim 1 , wherein the semiconductor device comprises 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.
13 . The method of claim 12 , wherein the copper-based conductive line structure comprises a copper bit line which is electrically connected to the drain region of the three dimensional memory device.
14 . The method of claim 1 , wherein:
the connection-level metal interconnect structure comprises a top surface that is formed within a first horizontal plane including a top surface of the connection-level dielectric layer;
a top surface of the single line-and-via-level dielectric layer is located within a second horizontal plane;
a sidewall of the via portion vertically extends from the first horizontal plane to a third horizontal plane including a bottom surface of the line portion; and
a sidewall of the line portion vertically extends from the third horizontal plane to the second horizontal plane.
15 . The method of claim 14 , wherein all sidewall surfaces of the integrated line-and-via cavity are surfaces of the single line-and-via-level dielectric layer.
16 . The method of claim 15 , wherein an entirety of a bottom surface of the line-and-via-level dielectric layer is formed within the first horizontal plane.
17 . The method of claim 1 , wherein both the line portion and the via portion of the integrated line-and-via cavity are formed by etching the single line-and-via-level dielectric layer after formation of the entire single line-and-via-level dielectric layer.
18 . The method of claim 17 , wherein the step of selectively growing the conductive via structure occurs after forming both the line portion and the via portion of the integrated line-and-via cavity.
19 . The method of claim 18 , wherein the step of forming the copper-based conductive line structure occurs after the step of selectively growing the conductive via structure.