Selective titanium nitride deposition using oxides of lanthanum masks

{
  "publication_number": "US10332747B1",
  "country": "US",
  "kind": "B1",
  "title": "Selective titanium nitride deposition using oxides of lanthanum masks",
  "abstract": "In an exemplary method, a dielectric layer is deposited on a substrate. A masking layer is formed over a first region and a second region of the dielectric layer. The masking layer is made of an oxide of lanthanum. The masking layer is removed from the second region of the dielectric layer. A work function layer is formed directly on only the second region of the dielectric layer. The work function layer is made of titanium nitride that is formed by using a combination of titanium tetrachloride and ammonia (TiCl4/NH3).",
  "claims": [
    "1. A method, comprising: depositing a dielectric layer on a substrate; forming a masking layer over a first region and a second region of the dielectric layer, the masking layer comprising an oxide of lanthanum; removing the masking layer from the second region of the dielectric layer; and exposing the masking layer and the second region of the dielectric layer to a titanium material to form a titanium nitride layer directly on only the second region of the dielectric layer, wherein the oxide of lanthanum prevents the titanium nitride from being formed on the masking layer.",
    "2. The method according to claim 1, wherein removing the masking layer comprises etching the masking layer.",
    "3. The method according to claim 1, wherein forming the titanium nitride layer further comprises: supplying titanium tetrachloride (TiCl4) to the substrate, purging the TiCl4 with nitrogen (N2), supplying ammonia (NH3) to the substrate, and purging the NH3 with N2.",
    "4. The method according to claim 3, further comprising: cyclically repeating supplying TiCl4, purging with N2, and supplying NH3, to grow titanium nitride (TiN) on the dielectric layer.",
    "5. The method according to claim 4, wherein the dielectric layer comprises hafnium dioxide (HfO2).",
    "6. The method according to claim 5, further comprising: soaking the masking layer in ammonia (NH3) before supplying TiCl4 to the substrate.",
    "7. The method according to claim 6, wherein the masking layer is soaked in ammonia for approximately 10-100 seconds.",
    "8. The method according to claim 1, further comprising: forming a stack of layers on the substrate; patterning the stack of layers to expose the second region of the dielectric layer; and performing one or more lithographic processes to form the masking layer on the top of the stack of layers.",
    "9. A method, comprising: providing a substrate having a top surface and a bottom surface; depositing a dielectric layer on the top surface of the substrate, the dielectric layer having a top surface and a bottom surface, wherein the bottom surface of the dielectric layer contacts the top surface of the substrate; depositing a first work function layer on the top surface of the dielectric layer, the first work function layer having a top surface and a bottom surface, wherein the bottom surface of the first work function layer contacts the top surface of the dielectric layer; forming a masking layer of an oxide of lanthanum over the first work function layer; selectively removing a portion of the masking layer and a portion of the first work function layer leaving an exposed region of the dielectric layer; and forming a second work function layer comprising titanium nitride directly on the exposed region of the dielectric layer by exposing the masking layer and the exposed portion of the dielectric layer to a titanium material, wherein the oxide of lanthanum prevents the titanium nitride from being formed on the masking layer.",
    "10. The method according to claim 9, wherein removing the masking layer comprises etching the masking layer.",
    "11. The method according to claim 9, wherein forming the second work function layer further comprises: supplying titanium tetrachloride (TiCl4) to the substrate, purging the TiCl4 with nitrogen (N2), supplying ammonia (NH3) to the substrate, and purging the NH3 with N2.",
    "12. The method according to claim 11, further comprising: cyclically repeating supplying TiCl4, purging with N2, and supplying NH3, to grow titanium nitride (TiN) on the dielectric layer.",
    "13. The method according to claim 12, further comprising: adjusting the height of the second work function layer relative to the height of the first work function layer by controlling the number of cycles for forming the second work function layer.",
    "14. The method according to claim 11, further comprising: soaking the masking layer in ammonia (NH3) before supplying TiCl4 to the substrate.",
    "15. The method according to claim 14, wherein the masking layer is soaked in ammonia for approximately 10-100 seconds.",
    "16. The method according to claim 9, wherein the dielectric layer comprises hafnium dioxide (HfO2).",
    "17. The method according to claim 9, further comprising: forming a stack of layers on the substrate; patterning the stack of layers to leave the exposed region of the dielectric layer; and performing lithographic processes to form the masking layer on the top of the stack of layers."
  ],
  "description_excerpt": "The present disclosure relates to semiconductor device fabrication, and, more specifically, to methods of forming gate structures using selective metal deposition.\n\nPhotolithography is a commonly used technique in the manufacture of semiconductor devices. The process uses patterns to define regions on a substrate. More specifically, with photolithography, a photoresist layer may be formed on a substrate, such as a silicon wafer, and then the resist layer is covered with a mask containing a pattern. The mask is exposed to radiation, such as ultraviolet light (UV), which is transmitted through transparent areas of the mask to cause a chemical reaction in corresponding regions of the photoresist. In other words, in the course of processing integrated circuits and the like in semiconductor devices, a standard sequence may involve putting down a layer of material, depositing a layer of photoresist on the layer of material, patterning the photoresist by projecting a pattern on it, and developing the resist to produce a pattern of open areas that expose the material, with the other areas of the material still covered by the resist.\n\nComplementary metal-oxide semiconductor (CMOS) devices typically employ at least one gate that is separated from a conducting channel (or channels) of the device by a gate dielectric material. Examples of such CMOS devices that employ a gate dielectric material include, but are not limited to, field effect transistors (FETs).\n\nDevices and methods herein provide a process to prevent a target surface of an oxide of lanthanum (LaOx) from being exposed on single patterning of the target surface.",
  "cpc": [
    "H10P 14/432",
    "C23C 16/042",
    "C23C 16/34",
    "C23C 16/45525",
    "H01L 21/28088",
    "H01L 21/28562",
    "H01L 29/4966",
    "H01L 29/517",
    "H10D 64/01318",
    "H10D 64/667",
    "H10D 64/685",
    "H10D 64/691",
    "H10D 84/0177",
    "H10D 84/038",
    "H10D 84/83135",
    "H10D 84/85"
  ],
  "ipc": [
    "C23C 16/04",
    "C23C 16/34",
    "C23C 16/455",
    "H01L 21/285",
    "H10D 64/66",
    "H10D 64/68",
    "H10D 84/03",
    "H10D 84/85"
  ],
  "assignees": [
    "GlobalFoundries Inc"
  ],
  "inventors": [
    "Koji Watanabe",
    "Meng Zhu",
    "Brian A. Cohen",
    "Matthew T. Whitman",
    "Balaji Kannan"
  ],
  "filing_date": "2018-01-24",
  "publication_date": "2019-06-25",
  "grant_date": "2019-06-25",
  "priority_date": "2018-01-24",
  "application_number": "US-201815878519-A",
  "family_id": "66996725",
  "cited_by_count": 291,
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}