Fin patterns with varying spacing without fin cut

{
  "publication_number": "US10211055B2",
  "country": "US",
  "kind": "B2",
  "title": "Fin patterns with varying spacing without fin cut",
  "abstract": "Methods of forming semiconductor fins include forming first spacers on a first sidewall of each of multiple mandrels using an angled deposition process. A second sidewall of one or more of the mandrels is masked in a finless region. Second spacers are formed on a second sidewall of all unmasked mandrels. Semiconductor fins are formed from a substrate using the first and second spacers as a pattern mask.",
  "claims": [
    "1. A method of forming semiconductor fins, comprising: forming first spacers on a first sidewall of each of a plurality of mandrels using an angled deposition process; masking a second sidewall of one or more of the plurality of mandrels in a finless region; forming second spacers on a second sidewall of all unmasked mandrels; forming said semiconductor fins from a substrate using the first and second spacers as a pattern mask.",
    "2. The method of claim 1, wherein forming the first spacers on the first sidewalls comprises oxidizing the first sidewalls using a gas cluster ion beam.",
    "3. The method of claim 2, wherein the mandrels comprise amorphous silicon and the gas cluster ion beam comprises oxygen.",
    "4. The method of claim 2, wherein the gas cluster ion beam has an angle relative to the substrate under the mandrels between about 10° and about 80°.",
    "5. The method of claim 1, wherein forming the second spacers on the second sidewalls comprising oxidizing the second sidewalls using a gas cluster ion beam.",
    "6. The method of claim 1, wherein forming the second spacers on the second sidewalls comprises an isotropic process.",
    "7. The method of claim 1, further comprising anisotropically etching spacer material from horizontal surfaces of the mandrels after unmasking the second sidewall of the one or more of the plurality of mandrels.",
    "8. The method of claim 1, wherein forming the semiconductor fins comprises forming no semiconductor fins in a region that was masked.",
    "9. The method of claim 1, wherein no semiconductor fin is removed after formation of the semiconductor fins.",
    "10. The method of claim 1, wherein masking the second sidewall of the one or more of the plurality of mandrels comprises forming a mask that directly contacts the second sidewall of the one or more of the plurality mandrels as well as a first spacer on an adjacent mandrel.",
    "11. The method of claim 1, wherein the substrate comprises a nitride pad layer that is directly on a semiconductor layer."
  ],
  "description_excerpt": "The present invention generally relates to semiconductor device fabrication and, more particularly, to forming semiconductor fins using a directional sidewall deposition process and sidewall image transfer.\n\nSidewall image transfer (SIT) is used in the fabrication of, e.g., fin field effect transistors (FinFETs) to create semiconductor fins that have a feature size that is smaller than the smallest available feature size in a lithographic process. SIT forms sidewalls on a mandrel and then removes the mandrel. The sidewalls are used as a mask for a subsequent etch that defines the semiconductor fins. However, this process creates pairs of fins - one on each sidewall of the mandrel. If a given fin is not part of the design, it is removed after formation by using a fin cut mask.\n\nAs fin pitch shrinks, fins are formed closer to one another. The inherent variations of misalignment of mask deposition produce a yield problem for close fin pitches, resulting in either incomplete removal of unneeded fins (when the fin cut mask fails to cover the unneeded fins) or an unintentional cut of device fins (when the fin cut mask encroaches onto the device fins).\n\nA method of forming semiconductor fins includes forming first spacers on a first sidewall of each of multiple mandrels using an angled deposition process. A second sidewall of one or more of the mandrels is masked in a finless region. Second spacers are formed on a second sidewall of all unmasked mandrels. Semiconductor fins are formed from a substrate using the first and second spacers as a pattern mask.",
  "cpc": [
    "H10P 76/4085",
    "H01L 21/0337",
    "H01L 21/3086",
    "H01L 21/32105",
    "H01L 29/6653",
    "H01L 29/6656",
    "H01L 29/66795",
    "H10D 30/024",
    "H10D 64/015",
    "H10D 64/021",
    "H10P 14/6308",
    "H10P 50/695"
  ],
  "ipc": [
    "H01L 29/66",
    "H10P 76/40"
  ],
  "assignees": [
    "International Business Machines Corp"
  ],
  "inventors": [
    "Marc A. Bergendahl",
    "Kangguo Cheng",
    "John R. Sporre",
    "Sean TEEHAN"
  ],
  "filing_date": "2018-03-05",
  "publication_date": "2019-02-19",
  "grant_date": "2019-02-19",
  "priority_date": "2016-05-12",
  "application_number": "US-201815911834-A",
  "family_id": "60294843",
  "cited_by_count": 7,
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}