# US 7,407,888 B2 · Semiconductor device and a fabrication process thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,407,888 B2 - Document ID: US7407888B2 - Status: Granted - Kind: B2 - Application number: 11/355,992 - Filed: 2006-02-17 - Published: 2006-12-21 - Granted: 2008-08-05 - Earliest claimed: 2005-06-17 - Assignees: Fujitsu Limited - Inventors: Takeshi Ito; Satoshi Inagaki; Yasunori Uchino; Kazuo Kawamura - Web page: https://patentgrep.com/patent/US7407888B2 ## CPC - H10W 20/081: {by forming openings in the dielectric parts} - H10W 20/035: {combinations of barrier, adhesion or liner layers, e.g. multi-layered barrier layers} - H10W 20/056: {by filling conductive material into holes, grooves or trenches} - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract A method of fabricating a semiconductor device comprises the steps of forming a contact hole in an insulation film so as to extend therethrough and so as to expose a conductor body at a bottom part of the contact hole, forming a barrier metal film of tungsten nitride on the bottom part and a sidewall surface of the contact hole with a conformal shape to the bottom part and the sidewall surface of the contact hole, forming a tungsten layer so as to fill the contact hole via the barrier metal film, and forming a tungsten plug in the contact hole by the tungsten layer by polishing away a part of the tungsten film on the insulation film until a surface of the insulation film is exposed, wherein there is conducted a step of cleaning a surface of the conductor body prior to the forming step of the barrier metal film. ## Claims ### Claim 1 A method of fabricating a semiconductor device having a contact structure comprising a conductor body, an insulation film covering said conductor body, and a contact plug penetrating through said insulation film and electrically connected to said conductor body, said method comprising the steps of: forming a contact hole in said insulation film to extend therethrough and to expose said conductor body at a bottom part of said contact hole; forming a barrier metal film of tungsten nitride over said bottom part and a sidewall surface of said contact hole with a conformal shape to said bottom part and said sidewall surface of said contact hole; forming a tungsten layer to fill said contact hole via said barrier metal film; and forming a tungsten plug in said contact hole by said tungsten layer by polishing away a part of said tungsten film over said insulation film until a surface of said insulation film is exposed, wherein there is conducted a step of cleaning a surface of said conductor body prior to said forming step of said barrier metal film, said barrier metal film is formed such that a nitrogen concentration therein decreases from a first side thereof contacting with said bottom surface and said sidewall surface of said contact hole to a second side contacting with said tungsten plug, and said barrier metal film causes transition to said tungsten plug continuously at said second side. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein said conductor body comprises a refractory metal silicide of any of NiSi, CoSi2, TaSi2, TiSi2 and PtSi. ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein said step of forming said barrier metal film is conducted such that a flow rate of a process gas used for a nitrogen source is set to a first flow rate when commencing formation of said barrier metal film, followed by gradual decrease of flow rate of said processing gas, such that said processing gas is supplied with a second flow rate smaller than said first flow rate at an end of forming said barrier metal film. ### Claim 4 (depends on 1) The methods as claimed in claim 1, wherein said step of forming said barrier metal film is conducted by using a WF6 gas, a NH3 gas, an Ar gas, and any of a SiH4 gas and a B2H6 gas for a processing gas. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein said step of forming said tungsten layer is conducted by using a WF6 gas, an Ar gas and any of a SiH4 gas and a B2H6 gas as a processing gas. ### Claim 6 (depends on 1) The method as claimed in claim 1, wherein said cleaning step is conducted by a sputter-etching process in an ambient of a rare gas and a hydrogen gas. ### Claim 7 (depends on 1) The method as claimed in claim 1, wherein said cleaning step is conducted by a sputtering process in a rare gas ambient. ### Claim 8 (depends on 1) The method as claimed in claim 1, wherein said cleaning step is conducted by an etching process in NF3 or hydrogen plasma. ### Claim 9 (depends on 1) The method as claimed in claim 1, wherein said semiconductor device is a logic semiconductor device having a diffusion region and a gate electrode, any of said diffusion region and said gate electrode is covered by a refractive silicide film, said contact structure being formed on said diffusion region and said gate electrode, said refractory silicide film being used as said conductor body. ### Claim 10 (depends on 1) The method as claimed in claim 1, wherein said semiconductor device includes a multilayer interconnection structure, said multilayer interconnection structure comprising a first interconnection layer and a second interconnection layer formed over said first interconnection layer via an interlayer insulation film, said contact structure being formed in said multilayer interconnection structure while using said first interconnection layer as said conductor body, such that said contact plug connects said first interconnection layer to said second interconnection layer. ### Claim 11 (depends on 1) The method as claimed in claim 1, wherein said step of cleaning causes etching in said surface of said conductor body with a depth of 5 -8 nm.