# US 9,040,421 B2 · Methods for fabricating integrated circuits with improved contact structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,040,421 B2 - Document ID: US9040421B2 - Status: Granted - Kind: B2 - Application number: 13/887,174 - Filed: 2013-05-03 - Published: 2014-11-06 - Granted: 2015-05-26 - Earliest claimed: 2013-05-03 - Assignees: Globalfoundries Inc. - Applicants: GLOBALFOUNDRIES, Inc. - Inventors: Xunyuan Zhang; Xuan Lin; Vimal Kamineni - Web page: https://patentgrep.com/patent/US9040421B2 ## CPC - H10W 20/425: {Barrier, adhesion or liner layers} - H10P 14/432: {using selective deposition} - H10P 50/667: {by liquid etching only} - H10P 50/73: {using masks for insulating materials} - H10W 20/033: {in openings in dielectrics} - H10W 20/037: {the barrier, adhesion or liner layers being on top of a main fill metal} - H10W 20/081: {by forming openings in the dielectric parts} - H10W 20/40: Interconnections external to wafers or substrates, e.g. back-end-of-line [BEOL] metallisations or vias connecting to gate electrodes - H10W 20/43: Layouts of interconnections - H10W 20/4403: {based on metals, e.g. alloys, metal silicides (H10W20/4484 takes precedence)} - H10W 20/4421: {the principal metal being copper} - H10W 20/47: comprising two or more dielectric layers having different properties, e.g. different dielectric constants - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract Methods for fabricating integrated circuits are provided. In an exemplary embodiment, a method for fabricating integrated circuits includes providing a semiconductor substrate disposed with a device therein and/or thereon. A contact structure including a barrier layer and a plug metal overlying the barrier layer is formed in electrical contact with the device. A hardmask is formed overlying the contact structure. The method includes performing an etch to form a via opening through the hardmask and to expose the barrier layer and the plug metal. Further, the method removes a remaining portion of the hardmask with a wet etchant, while the contact structure is configured to inhibit the wet etchant from etching the barrier layer. In the method, the via opening is filled with a conductive material to form an interconnect to the contact structure. ## Claims ### Claim 1 A method for fabricating integrated circuits, the method comprising: providing a semiconductor substrate disposed with a device therein and/or thereon; forming a contact structure in electrical contact with the device, wherein the contact structure includes a barrier layer and a plug metal overlying the barrier layer; forming a hardmask overlying the contact structure; performing an etch to form a via opening through the hardmask and to expose the barrier layer and the plug metal; after performing the etch to form the via opening through the hardmask, forming a contact cap on the fill metal and barrier layer; removing a remaining portion of the hardmask with a wet etchant, wherein the contact cap inhibits the wet etchant from etching the barrier layer; and filling the via opening with a conductive material to form an interconnect to the contact structure. ### Claim 2 (depends on 1) The method of claim 1 wherein forming a hardmask over the contact structure comprises forming a titanium nitride hardmask over the contact structure. ### Claim 3 (depends on 1) The method of claim 1 further comprising depositing dielectric material over the semiconductor substrate, wherein forming a contact structure comprises: etching a contact opening through the dielectric material; depositing a barrier material in the contact opening to form the barrier layer; and depositing a fill metal over the barrier layer to form the plug metal filling the contact opening. ### Claim 4 (depends on 1) The method of claim 1 further comprising: depositing a dielectric material over the contact structure, wherein performing the etch to form the via opening comprises etching the dielectric material to form the via opening therethrough, wherein forming the contact cap on the fill metal and barrier layer comprises selectively depositing tungsten in the via opening on the fill metal and laterally growing the tungsten to cover the barrier layer. ### Claim 5 (depends on 1) The method of claim 1 wherein removing a remaining portion of the hardmask with a wet etchant comprises removing a remaining portion of the hardmask with an etchant including an oxidizer, a pH adjustor and/or a tungsten corrosion inhibitor. ### Claim 6 (depends on 1) The method of claim 1 further comprising: depositing a dielectric material over the contact structure, wherein performing the etch to form the via opening comprises etching the dielectric material to form the via opening therethrough, wherein forming the contact cap on the fill metal and barrier layer comprises selectively depositing tungsten in the via opening on the fill metal and laterally growing the tungsten into contact with the dielectric material to cover the barrier layer. ### Claim 7 (depends on 1) The method of claim 1 wherein forming a contact structure in electrical contact with the device comprises depositing fluorine free tungsten (FFW), tungsten nitride, or tungsten carbide to form the barrier layer. ### Claim 8 (depends on 7) The method of claim 7 wherein removing a remaining portion of the hardmask with a wet etchant comprises removing a remaining portion of the hardmask with a wet etchant selective to titanium nitride over FFW, such that the contact structure is configured to inhibit the wet etchant from etching the barrier layer. ### Claim 9 (depends on 7) The method of claim 7 further comprising depositing dielectric material over the semiconductor substrate, wherein forming a contact structure comprises: etching a contact opening through the dielectric material; and exposing the substrate to a non-halogen organometallic tungsten precursor and a reducing agent to deposit a tungsten-rich film in the contact opening, wherein the tungsten-rich film is the barrier layer. ### Claim 10 (depends on 9) The method of claim 9 wherein forming a contact structure further comprises substantially filling the contact opening with tungsten to form the plug metal. ### Claim 11 (depends on 7) The method of claim 7 further comprising depositing dielectric material over the semiconductor substrate, wherein forming a contact structure comprises: etching a contact opening through the dielectric material; exposing the semiconductor substrate to a non-halogen organometallic tungsten precursor and a reducing agent to deposit a tungsten-rich film in the contact opening; exposing the substrate to a tungsten-containing precursor to deposit one or more tungsten layers on the tungsten-rich film, wherein the tungsten-rich film and the one or more tungsten layers form the barrier layer. ### Claim 12 (depends on 11) The method of claim 11 wherein forming a contact structure further comprises substantially filling the contact opening with tungsten to form the plug metal. ### Claim 13 A method for fabricating integrated circuits, the method comprising: providing a semiconductor substrate disposed with a device therein and/or thereon; forming a contact structure in electrical contact with the device, wherein the contact structure includes a barrier layer and a plug metal; forming a dielectric layer and a hardmask over the contact structure; etching the hardmask and dielectric layer to form a via opening through the hardmask and dielectric layer and to expose the contact structure; forming a contact cap in the via opening over the plug metal and the barrier layer; removing a remaining portion of the hardmask with a wet etchant, wherein the contact cap inhibits the wet etchant from etching the barrier layer; and filling the via opening with a conductive material to form an interconnect to the contact structure. ### Claim 14 (depends on 13) The method of claim 13 wherein forming the contact cap on the barrier layer and the plug metal comprises selectively growing the contact cap from the plug metal into contact with the dielectric layer to cover the barrier layer. ### Claim 15 (depends on 13) The method of claim 13 further comprising depositing dielectric material over the semiconductor substrate, wherein forming a contact structure comprises: etching a contact opening through the dielectric material; depositing a barrier material in the contact opening to form the barrier layer; and depositing a fill metal over the barrier layer to form the plug metal, wherein the plug metal fills the contact opening. ### Claim 16 (depends on 13) The method of claim 13 wherein forming the contact cap in the via opening over the fill metal and barrier layer comprises selectively depositing tungsten on the fill metal and covering the barrier layer by lateral growth of the tungsten. ### Claim 17 A method for fabricating integrated circuits, the method comprising: providing a semiconductor substrate disposed with a device therein and/or thereon; forming a contact structure in electrical contact with the device, wherein forming the contact structure includes depositing fluorine free tungsten (FFW), tungsten nitride, or tungsten carbide to form a barrier layer and forming a plug metal overlying the barrier layer; forming a hardmask overlying the contact structure; performing an etch to form a via opening through the hardmask and to expose the barrier layer and the plug metal; removing a remaining portion of the hardmask with a wet etchant, wherein the contact structure is configured to inhibit the wet etchant from etching the barrier layer; and filling the via opening with a conductive material to form an interconnect to the contact structure. ### Claim 18 (depends on 17) The method of claim 17 wherein removing a remaining portion of the hardmask with a wet etchant comprises removing a remaining portion of the hardmask with a wet etchant selective to titanium nitride over FFW, such that the contact structure is configured to inhibit the wet etchant from etching the barrier layer. ### Claim 19 (depends on 17) The method of claim 17 wherein forming the contact structure in electrical contact with the device comprises depositing fluorine free tungsten (FFW) to form the barrier layer. ### Claim 20 (depends on 17) The method of claim 17 wherein forming the contact structure in electrical contact with the device comprises depositing tungsten carbide to form the barrier layer.