Preparation of epitaxial graphene surfaces for atomic layer deposition of dielectrics
Processes for preparation of an epitaxial graphene surface to make it suitable for deposition of high-κ oxide-based dielectric compounds such as Al 2 O 3 , HfO 2 , TaO 5 , or TiO 2 are provided. A first process combines ex situ wet chemistry conditioning of an epitaxially grown graphene sample with an in situ pulsing sequence in the ALD reactor. A second process combines ex situ dry chemistry conditioning of the epitaxially grown graphene sample with the in situ pulsing sequence.
1. A process for functionalizing a surface of an epitaxial graphene sample (EG sample) for atomic layer deposition (ALD) of a dielectric in an ALD reactor, the process comprising:
(1) subjecting the EG sample to an ex situ functionalization step, the ex situ functionalization step comprising exposing the EG sample to a fluorine gas diluted in an inert carrier gas outside the ALD reactor, the fluorine gas forming C—F bonds on the surface of the EG sample capable of nucleation of dielectrics thereon; and
(2) subjecting the EG sample having C—F bonds thereon to an in situ treatment cycle to complete the surface functionalization, the in situ treatment cycle comprising a plurality of H 2 O pulses inside the ALD reactor, wherein each of the plurality of H 2 O pulses is separated only by a corresponding purge step;
wherein the functionalized surface of the EG sample is configured for the deposition of a smooth and conformal dielectric layer thereon.
2. The process according to claim 1 , wherein the fluorine gas is XeF 2 .
3. The process according to claim 2 , wherein the partial pressure of the XeF 2 is about 0.8 Torr and the partial pressure of the carrier gas is about 35 Torr.
4. The process according to claim 1 , wherein the EG sample is exposed to the fluorine gas in a pulsed mode.
5. The process according to claim 4 , wherein the EG sample is exposed to the fluorine gas in a series of 6 pulses of 20 seconds each.
6. The process according to claim 1 , wherein the EG sample is exposed to the fluorine gas in a continuous mode.
7. The process according to claim 6 , wherein the EG sample is exposed to the fluorine gas in a continuous mode for greater than 120 seconds at 10 standard cubic centimeters per minute active gas flow.
8. The process according to claim 1 , wherein the EG sample is an Si-face epitaxially grown graphene sample.
9. The process according to claim 1 , wherein the EG sample is a C-face epitaxially grown graphene sample.
10. A process for functionalizing a surface of an epitaxial graphene sample (EG sample) for atomic layer deposition (ALD) of a dielectric in an ALD reactor, the process comprising:
(1) subjecting the EG sample to an ex situ functionalization step, the ex situ functionalization step comprising exposing the EG sample to a chlorine gas diluted in an inert carrier gas outside the ALD reactor, the fluorine gas forming C—Cl— bonds on the surface of the EG sample capable of nucleation of dielectrics thereon; and
(2) subjecting the EG sample having C—Cl— bonds thereon to an in situ treatment cycle to complete the surface functionalization, the in situ treatment cycle comprising a plurality of H 2 O pulses inside the ALD reactor, wherein each of the plurality of H 2 O pulses is separated only by a corresponding purge step;
wherein the functionalized surface of the EG sample is configured for the deposition of a smooth and conformal dielectric layer thereon.
11. The process according to claim 10 , wherein the EG sample is an Si-face epitaxially grown graphene sample.
12. The process according to claim 10 , wherein the EG sample is a C-face epitaxially grown graphene sample.