Atomic layer etching using a boron-containing gas and hydrogen fluoride gas

1. A method of atomic layer etching (ALE), the method comprising:

providing a substrate; and

in the absence of a plasma, exposing the substrate to hydrogen fluoride (HF) gas and a boron-containing gas to etch the substrate, wherein the exposing includes alternating exposures to the hydrogen fluoride gas and the boron-containing gas that are repeated at least once to further etch the substrate.

2. The method of claim 1 , wherein the boron-containing gas contains a boron hydride, a boron halide, a boron amide, an organo boride, or a combination thereof.

3. The method of claim 1 , wherein the boron-containing gas is selected from the group consisting of BH 3 , BCl 3 , B(CH 3 ) 3 , and B(N(CH 3 ) 2 ) 3 .

4. The method of claim 1 , wherein the boron-containing gas is selected from the group consisting of BH 3 , B(CH 3 ) 3 , and B(N(CH 3 ) 2 ) 3 .

5. A method of atomic layer etching (ALE), the method comprising:

providing a substrate containing a metal oxide film;

exposing the substrate to hydrogen fluoride (HF) gas to form a fluorinated surface layer on the metal oxide film; and

exposing the substrate to a boron-containing gas to remove the fluorinated surface layer from the metal oxide film, wherein the exposing steps are performed in the absence of a plasma.

6. The method of claim 5 , wherein the exposures are repeated at least once to further etch the metal oxide film.

7. The method of claim 5 , wherein the boron-containing gas contains a boron hydride, a boron halide, a boron amide, an organo boride, or a combination thereof.

8. The method of claim 5 , wherein the boron-containing gas is selected from the group consisting of BH 3 , BCl 3 , B(CH 3 ) 3 , and B(N(CH 3 ) 2 ) 3 .

9. The method of claim 5 , wherein the boron-containing gas is selected from the group consisting of BH 3 , B(CH 3 ) 3 , and B(N(CH 3 ) 2 ) 3 .

10. The method of claim 5 , wherein the metal oxide film is selected from the group consisting of Al 2 O 3 , HfO 2 , TiO 2 , ZrO 2 , Y 2 O 3 , La 2 O 3 , UO 2 , Lu 2 O 3 , Ta 2 O 5 , Nb 2 O 5 , ZnO, MgO, CaO, BeO, V 2 O 5 , FeO, FeO 2 , CrO, Cr 2 O 3 , CrO 2 , MnO, Mn 2 O 3 , RuO, CoO, WO 3 , and combinations thereof.

11. The method of claim 5 , further comprising gas purging with an inert gas between the exposing steps.

12. A method of atomic layer etching (ALE), the method comprising:

providing a substrate; and

in the absence of a plasma, exposing the substrate to hydrogen fluoride (HF) gas and a boron-containing gas to etch the substrate, wherein the boron-containing gas contains a boron hydride, a boron halide, a boron amide, an organo boride, or a combination thereof, and wherein the exposing includes alternating exposures to the hydrogen fluoride gas and the boron-containing gas that are repeated at least once to further etch the substrate.

13. The method of claim 12 , wherein the boron-containing gas is selected from the group consisting of BH 3 , BCl 3 , B(CH 3 ) 3 , and B(N(CH 3 ) 2 ) 3 .

14. The method of claim 12 , wherein the boron-containing gas is selected from the group consisting of BH 3 , B(CH 3 ) 3 , and B(N(CH 3 ) 2 ) 3 .

15. The method of claim 12 , wherein the substrate contains a metal oxide film selected from the group consisting of Al 2 O 3 , HfO 2 , TiO 2 , ZrO 2 , Y 2 O 3 , La 2 O 3 , UO 2 , Lu 2 O 3 , Ta 2 O 5 , Nb 2 O 5 , ZnO, MgO, CaO, BeO, V 2 O 5 , FeO, FeO 2 , CrO, Cr 2 O 3 , CrO 2 , MnO, Mn 2 O 3 , RuO, CoO, WO 3 , and combinations thereof.

16. The method of claim 12 , further comprising gas purging with an inert gas between the alternating exposures.