Methods of graphene growth and related structures

• US 10,290,808 B2
• Filed: 03/19/2018
• Issued: 05/14/2019
• Est. Priority Date: 05/31/2016
• Status: Active Grant

• Current Assignee: National Taiwan University (Government of The Republic of China), Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: National Taiwan University (Government of The Republic of China), Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Chen, Miin-Jang, Pan, Samuel C., Hsieh, Chung-Yen
• Primary Examiner(s): Naraghi, Ali
• Application Number:
  US15/925,195
• Publication Number:
  US 20180212151A1
• Time in Patent Office: 421 Days
• Field of Search: None
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02527 Carbon, e.g. diamond-like carbon
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02664 Aftertreatments planarisation in general H01L21/304
• CPC Class Codes: H01L 21/02672 using crystallisation enhancing elements
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 29/1606 Graphene
• CPC Class Codes: H01L 29/66742 Thin film unipolar transistors
• CPC Class Codes: H10K 10/464 Lateral top-gate IGFETs comprising only a single gate
• CPC Class Codes: H10K 10/484 characterised by the channel regions
• CPC Class Codes: H10K 71/18 using non-liquid printing techniques, e.g. thermal transfer printing from a donor sheet
• CPC Class Codes: H10K 85/20 Carbon compounds, e.g. carbon nanotubes or fullerenes
• CPC Class Codes: H10K 85/221 Carbon nanotubes

Abstract

A method and structure for providing uniform, large-area graphene by way of a transfer-free, direct-growth process. In some embodiments, a SAM is used as a carbon source for direct graphene synthesis on a substrate. For example, a SAM is formed on an insulating surface, and a metal layer is formed over the SAM. The metal layer may serve as a catalytic metal, whereby the SAM is converted to graphene following an annealing process. The SAM is deposited using a VPD process (e.g., an ALD process and/or an MLD process). In some embodiments, a CNT having a controlled diameter may be formed on the surface of a nanorod by appropriately tuning the geometry of the nanorod. Additionally, in some embodiments, a curved graphene transistor may be formed over a curved oxide surface, thereby providing a band gap in a channel region of the graphene transistor.

Claims

1. A method, comprising:

providing a substrate including a nanorod extending therefrom, wherein the nanorod includes an insulating outer surface that traverses a circumference of the nanorod;

forming, by a vapor phase deposition process, a carbon-containing layer over the insulating outer surface;

depositing a metal layer over the carbon-containing layer; and

after depositing the metal layer, performing an annealing process, wherein the annealing process serves to convert the carbon-containing layer into a carbon nanotube (CNT).

2. The method of claim 1, wherein the CNT includes one of a single-wall CNT (SW-CNT), a double-wall CNT (DW-CNT), and a multi-wall CNT (MW-CNT).

3. The method of claim 1, wherein the nanorod includes a first diameter, and wherein the CNT includes a second diameter substantially equal to the first diameter.

4. The method of claim 1, wherein the vapor phase deposition process includes one of an atomic layer deposition (ALD) process and a molecular layer deposition (MLD) process.

5. The method of claim 1, wherein the carbon-containing layer includes a self-assembled monolayer (SAM).

6. The method of claim 5, wherein the SAM includes one of tridecafluoro-tetrahydrooctyl-trichlorosilane (FOTS), and dodecyltrichlorosilane (DTS).

7. The method of claim 1, wherein the metal layer includes one of Ni, Cu, Pt, Fe, Co, Au, and a Cu—

Ni alloy.

8. The method of claim 1, further comprising:

after performing the annealing process, removing the metal layer and performing a thermal treatment in a reducing atmosphere; and

after performing the thermal treatment, forming source and drain electrodes in contact with the CNT;

after forming the source and drain electrodes, depositing a top-gate dielectric layer over the CNT; and

forming a top-gate electrode on the top-gate dielectric.

9. The method of claim 8, wherein the thermal treatment is performed at a temperature of about 800-1200 degrees Celsius and in a reducing atmosphere including one of a H₂/Ar atmosphere, a H₂/N₂ atmosphere, and a N₂H₂ atmosphere.

10. The method of claim 1, wherein a CNT band gap is determined at least in part by the first diameter.

11. The method of claim 1, further comprising:

prior to forming the carbon-containing layer, cleaning the insulating outer surface of the nanorod.

12. A method, comprising:

forming a plurality of nanorods extending from a substrate;

depositing an oxide layer over an outer surface of each of the plurality of nanorods;

forming a carbon-containing layer, the carbon-containing layer including a self-assembled monolayer (SAM), conformally over the oxide layer;

depositing a metal layer over the SAM; and

after depositing the metal layer, performing an annealing process to convert the SAM into a carbon nanotube (CNT).

13. The method of claim 12, wherein each of the plurality of nanorods have a first diameter, wherein each of the plurality of nanorods including the oxide layer have a second diameter greater than the first diameter, and wherein the CNT includes a third diameter substantially equal to the second diameter.

14. The method of claim 12, wherein the SAM includes one of tridecafluoro-tetrahydrooctyl-trichlorosilane (FOTS) and dodecyltrichlorosilane (DTS).

15. The method of claim 12, further comprising:

after performing the annealing process, etching the metal layer and thermally treating the CNT.

16. The method of claim 15, wherein the thermally treating the CNT includes annealing the CNT at a temperature of about 800-1200 degrees Celsius in a reducing atmosphere including one of a H₂/Ar atmosphere, a H₂/N₂ atmosphere, and a N₂H₂ atmosphere.

17. A method, comprising:

providing a first substrate including a nanowire extending therefrom;

forming a self-assembled monolayer (SAM) over an outer surface of the nanowire;

depositing a metal layer over the SAM;

after depositing the metal layer, performing a pyrolysis process to convert the SAM into a carbon nanotube (CNT);

transferring the CNT onto an insulating surface of a second substrate; and

forming source and drain electrodes in contact with the CNT, depositing a top-gate dielectric layer over the CNT, and forming a top-gate electrode on the top-gate dielectric.

18. The method of claim 17, wherein the outer surface of the nanowire includes an insulating outer surface that traverses a circumference of the nanowire.

19. The method of claim 17, wherein the CNT includes one of a single-wall CNT (SW-CNT), a double-wall CNT (DW-CNT), and a multi-wall CNT (MW-CNT).

20. The method of claim 17, wherein the SAM includes one of tridecafluoro-tetrahydrooctyl-trichlorosilane (FOTS), and dodecyltrichlorosilane (DTS).