Ultra-thin film formation using gas cluster ion beam processing

1. A method of preparing a thin film, comprising:

forming an ultra-thin hermetic film over at least a portion of a substrate using at least one gas cluster ion beam (GCIB),

wherein said ultra-thin hermetic film has a thickness less than 5 nm, and

wherein said forming includes (a) optionally growing a mixed sublayer in a surface portion of said substrate by mixing at least one atomic constituent in said substrate with at least one film-forming atomic constituent in said at least one GCIB, and (b) depositing one or more film-forming atomic constituents from said at least one GCIB over said surface portion of said substrate to form a deposited layer, wherein said mixed sublayer and said deposited layer together form the ultra-thin hermetic film.

2. The method of claim 1 , comprising:

providing said substrate in a reduced-pressure environment;

generating said at least one GCIB in said reduced-pressure environment from a pressurized gas mixture;

selecting a beam acceleration potential and a beam dose to achieve said thickness of less than 5 nm;

accelerating said at least one GCIB according to said beam acceleration potential;

irradiating said accelerated at least one GCIB onto said at least a portion of said substrate according to said beam dose; and

forming said ultra-thin hermetic film on said at least a portion of said substrate to achieve said thickness.

3. The method of claim 2 , wherein said thickness is less than about 3 nm.

4. The method of claim 2 , further comprising:

further selecting said beam acceleration potential and said beam dose to achieve a surface roughness of an upper surface of said ultra-thin hermetic film less than about 10 Å.

5. The method of claim 4 , wherein said beam acceleration potential is selected to be less than about 50 kV.

6. The method of claim 4 , wherein said beam acceleration potential is selected to be less than about 5 kV.

7. The method of claim 4 , further comprising:

modifying a beam energy distribution to change said thickness, or said surface roughness, or both.

8. The method of claim 7 , wherein said modifying said beam energy distribution comprises:

broadening said beam energy distribution to decrease said thickness, or decrease said surface roughness, or both; or

narrowing said beam energy distribution to increase said thickness, or increase said surface roughness, or both.

9. The method of claim 7 , wherein said modifying said beam energy distribution comprises directing said at least one GCIB along a GCIB path through an increased pressure region such that at least a portion of said GCIB path traverses said increased pressure region.

10. The method of claim 2 , further comprising:

pre-treating said substrate; or

post-treating said ultra-thin hermetic film to alter a property of said ultra-thin hermetic film; or

both pre-treating said substrate and post-treating said ultra-thin hermetic film.

11. The method of claim 10 , comprising said post-treating or both said pre-treating and said post-treating, and wherein said post-treating comprises exposing said ultra-thin hermetic film to another GCIB, annealing said ultra-thin hermetic film, exposing said ultra-thin hermetic film to a slotted plane antenna (SPA) plasma, exposing said ultra-thin hermetic film to electro-magnetic (EM) radiation, exposing said ultra-thin hermetic film to a photon source, exposing said ultra-thin hermetic film to an ion source, or exposing said ultra-thin hermetic film to an electron source, or any combination of two or more thereof.

12. The method of claim 2 , wherein said pressurized gas mixture comprises an oxygen-containing gas, a nitrogen-containing gas, a carbon-containing gas, a hydrogen-containing gas, a silicon-containing gas, a phosphorous-containing gas, a boron-containing gas, an arsenic-containing gas, a sulfur-containing gas, or a germanium-containing gas, or a combination of two or more thereof.

13. The method of claim 2 , wherein said at least one GCIB is generated having an energy per cluster atom ranging from about 1 eV/cluster atom to about 10 eV/cluster atom.

14. The method of claim 1 , wherein said ultra-thin hermetic film is formed over a metal line, the method further comprising:

forming an inter-level dielectric layer above said ultra-thin hermetic film; and

etching a pattern into said inter-level dielectric layer and stopping on said ultra-thin hermetic film to thereby form an interconnect structure.

15. The method of claim 1 , further comprising:

prior to said forming said ultra-thin hermetic film, forming an inter-level dielectric layer;

depositing said ultra-thin hermetic film over said inter-level dielectric layer using said at least one GCIB;

etching a trench, or via, or both into said inter-level dielectric layer;

metalizing said trench, or via, or both; and

polishing said metalized trench, or via, or both until said ultra-thin film is reached to thereby form an interconnect structure.

16. The method of claim 1 , further comprising, prior to said forming said ultra-thin hermetic film:

forming an inter-level dielectric layer;

forming a chemical-mechanical polishing (CMP) stop layer over said inter-level dielectric layer;

etching a trench, or via, or both into said inter-level dielectric layer;

metalizing said trench, or via, or both; and

polishing said metalized trench, or via, or both until said CMP stop layer is reached without over-polishing said metalized trench, or via, or both;

wherein said ultra-thin film is formed over said polished, metalized trench, or via, or both using said at least one GCIB to thereby form an interconnect structure.

17. The method of claim 1 , wherein said forming said ultra-thin hermetic film includes forming a first ultra-thin hermetic film over a metal line using a first GCIB, the method further comprising:

forming a first inter-level dielectric layer above said first ultra-thin hermetic film;

forming a second ultra-thin hermetic film over said first inter-level dielectric layer using a second GCIB;

forming a second inter-level dielectric layer over said second ultra-thin hermetic film;

etching a via into said first inter-level dielectric layer and stopping on said first ultra-thin hermetic film; and

etching a trench into said second inter-level dielectric layer and stopping on said second ultra-thin hermetic film to thereby form an interconnect structure, wherein each of said first and second ultra-thin hermetic films have said thickness less than 5 nm.

18. The method of claim 17 , further comprising:

metalizing said via and said trench; and

polishing said metallized trench and via.

19. The method of claim 1 , wherein said forming said ultra-thin hermetic film includes growing said mixed sublayer, followed by said depositing.

20. The method of claim 19 , wherein said forming said mixed sublayer includes using a first GCIB, and said depositing includes using a second GCIB.

21. A method of preparing a thin film, comprising:

forming an inter-level dielectric layer over at least a portion of a substrate;

depositing an ultra-thin hermetic film over said inter-level dielectric layer using a gas cluster ion beam (GCIB), wherein said ultra-thin hermetic film has a thickness less than 5 nm;

etching a trench, or via, or both into said inter-level dielectric layer;

metalizing said trench, or via, or both; and

polishing said metalized trench, or via, or both until said ultra-thin hermetic film is reached to thereby form an interconnect structure.

22. The method of claim 21 , comprising:

providing said substrate in a reduced-pressure environment;

generating said GCIB in said reduced-pressure environment from a pressurized gas mixture;

selecting a beam acceleration potential and a beam dose to achieve said thickness of less than 5 nm;

accelerating said GCIB according to said beam acceleration potential;

irradiating said accelerated GCIB onto said inter-level dielectric layer according to said beam dose; and

depositing said ultra-thin hermetic film to achieve said thickness.

23. The method of claim 22 , further comprising:

further selecting said beam acceleration potential and said beam dose to achieve a surface roughness of an upper surface of said ultra-thin hermetic film less than about 10 Å.