Protective self-aligned buffer layers for damascene interconnects

{
  "publication_number": "US7727880B1",
  "country": "US",
  "kind": "B1",
  "title": "Protective self-aligned buffer layers for damascene interconnects",
  "abstract": "Protective self aligned buffer (PSAB) layers are layers of material that are selectively formed at the surface of metal layers in a partially fabricated semiconductor device. In a Damascene interconnect, PSAB layer typically resides at an interface between the metal layer and a dielectric diffusion barrier layer. PSAB layers promote improved adhesion between a metal layer and an adjacent dielectric diffusion barrier layer. Further, PSAB layers can protect metal surfaces from inadvertent oxidation during fabrication process. A PSAB layer may be formed entirely within the top portion of a metal layer, by, for example, chemically converting metal surface to a thin layer of metal silicide. Thickness of PSAB layers, and, consequently resistance of interconnects can be controlled by partially passivating metal surface prior to formation of PSAB layer. Such passivation can be accomplished by controllably treating metal surface with a nitrogen-containing compound to convert metal to metal nitride.",
  "claims": [
    "1. A method of forming a protective self aligned buffer (PSAB) layer of material on or within an exposed metal surface of a partially fabricated semiconductor device having a pattern of metal layers in a dielectric, the method comprising: (a) contacting the partially fabricated semiconductor device with a PSAB-forming reactant, such that the PSAB-forming reactant reacts with metal atoms of the metal layer and chemically transforms the top portion of the metal layer into a first PSAB layer, wherein said first PSAB layer resides entirely within said metal layer; and (b) subsequently contacting the first PSAB layer with a pinning process gas comprising a hydrocarbon in a plasma discharge to form a pinned protective self-aligned buffer layer on or within the metal layer.",
    "2. The method of claim 1, wherein the metal layer comprises a metal fill within a damascene region of the partially fabricated semiconductor device.",
    "3. The method of claim 1, wherein the metal layer comprises copper.",
    "4. The method of claim 1, wherein (a) and (b) are performed in a PECVD apparatus and (a) is performed without use of plasma.",
    "5. The method of claim 1, wherein the first PSAB layer is formed to a depth ranging from about 10 Å to about 1000 Å into the metal layer.",
    "6. The method of claim 1, wherein (a) comprises flowing the PSAB forming reactant at a flow rate ranging from about 0.001 sccm to about 10000 sccm, wherein (a) is performed at a temperature ranging from about 20° C. to about 500° C., and in a pressure range of between about 10 mTorr to about 100 Torr, and wherein (b) comprises flowing the PSAB forming reactant at a flow rate ranging from about 0.001 sccm to about 10000 sccm, wherein (b) is performed at a temperature ranging from about 20° C. to about 500° C., and in a pressure range of between about 10 mTorr to about 100 Torr.",
    "7. The method of claim 1, wherein the PSAB forming reactant comprises a gas or a vapor selected from the group consisting of SiH 4, GeH 4, PH 3, B 2 H 6, AsH 3, CH 4, C x H y, H 2 S, H 2 Se, and H 2 Te.",
    "8. The method of claim 1, wherein the first protective self-aligned buffer layer comprises material selected from the group consisting of Cu x Si y, Cu x Ge y, Cu x P y, Cu x B y, Cu x As y, Cu x C y, Cu x S y, Cu x Se y, and Cu x Te y.",
    "9. The method of claim 1, wherein the hydrocarbon used during (b) is selected from a group consisting of methane, ethane, ethylene, acetylene, propane, propene, propyne, cyclopropane, cyclobutane, butanes, butenes, butynes, and benzene.",
    "10. The method of claim 1, wherein the pinning process gas further comprises a gas or a vapor selected from the group consisting of N 2, NH 3, H 2, and mixtures thereof.",
    "11. The method of claim 1, wherein (b) does not comprise depositing material to a thickness of greater than 10 Å on the dielectric portions of the partially fabricated semiconductor device.",
    "12. The method of claim 1, further comprising prior to (a): contacting the partially fabricated semiconductor device with a nitrogen-containing reactant, wherein the nitrogen-containing reactant selectively reacts with metal atoms of the metal layer and thereby partially passivates the metal surface to the formation of the first PSAB layer.",
    "13. The method of claim 1, wherein the pinning process gas further comprises a nitrogen-containing gas.",
    "14. A method of forming a PSAB layer of material on or within an exposed metal surface of a partially fabricated semiconductor device having a pattern of metal layers in a dielectric, the method comprising: (a) contacting the partially fabricated semiconductor device with a PSAB-forming reactant, such that the PSAB-forming reactant reacts with metal atoms of the metal layer and chemically transforms the top portion of the metal layer into a first PSAB layer, wherein said first PSAB layer resides entirely within said metal layer; (b) subsequently contacting the partially fabricated semiconductor device with a pinning reactant in a plasma discharge to form a pinned PSAB layer on or within the metal layer; and (c) treating the partially fabricated semiconductor device surface with H 2 in a plasma discharge concurrently with (b) or after (b).",
    "15. The method of claim 14, wherein operations (a) comprises flowing a process gas comprising the PSAB-forming reactant at a flow rate ranging from about 0.001 sccm to about 10000 sccm, wherein (a) is performed at a temperature ranging from about 20° C. to about 500° C., and in a pressure range of between about 10 mTorr to about 100 Torr and wherein operation (b) comprises flowing a process gas comprising the pinning reactant at a flow rate ranging from about 0.001 sccm to about 10000 sccm, wherein (b) is performed at a temperature ranging from about 20° C. to about 500° C., and in a pressure range of between about 10 mTorr to about 100 Torr.",
    "16. The method of claim 14, wherein operations (b) and (c) are performed concurrently, and the pinning reactant is selected from the group consisting of N 2, NH 3, a hydrocarbon, a gas from the family of methyl-substituted silanes, a gas from the family of methyl-substituted amines hexamethyldisilazane (HMDS), and mixtures thereof.",
    "17. The method of claim 14, wherein (b) and (c) are performed concurrently and comprises contacting the partially fabricated semiconductor device having the first PSAB layer with a process gas comprising H 2 and a pinning reactant selected from the group consisting of NH 3, N 2 and mixtures thereof, in a plasma discharge.",
    "18. The method of claim 14, wherein (c) is performed subsequent to (b) and the pinning reactant is selected from the group consisting of N 2, NH 3, a hydrocarbon, a gas from the family of methyl-substituted silanes, a gas from the family of methyl-substituted amines hexamethyldisilazane (HMDS), and mixtures thereof.",
    "19. The method of claim 14, further comprising prior to (a): contacting the partially fabricated semiconductor device with a nitrogen-containing reactant, wherein the nitrogen-containing reactant selectively reacts with metal atoms of the metal layer and thereby partially passivates the metal surface to the formation of the first PSAB layer."
  ],
  "cpc": [
    "H10W 20/064",
    "H10W 20/035",
    "H10W 20/037",
    "H10W 20/048",
    "H10W 20/0523",
    "H10W 20/055",
    "H10W 20/056",
    "H10W 20/076",
    "H10W 20/077",
    "H10W 20/425"
  ],
  "assignees": [
    "NOVELLUS SYSTEMS INC"
  ],
  "filing_date": "2007-02-20",
  "publication_date": "2010-06-01",
  "grant_date": "2010-06-01",
  "priority_date": "2004-11-03",
  "application_number": "US-70929407-A",
  "family_id": "42200165",
  "citations": [
    "JP2000252278A",
    "US2001006701A1",
    "US2002066411A1",
    "US2002155702A1",
    "US2003209738A1",
    "US2004097075A1",
    "US2006046479A1",
    "US2007035029A1",
    "US2007037388A1",
    "US2007105377A1",
    "US4282268A",
    "US6143657A",
    "US6181013B1",
    "US6271595B1",
    "US6750541B2",
    "US6821890B2",
    "US6855645B2",
    "US6974768B1",
    "US7060619B2",
    "US7202185B1",
    "US7211509B1",
    "US7239017B1",
    "US7282438B1",
    "US7297608B1",
    "US7396759B1",
    "US7420275B1"
  ]
}