Atomic layer etching using a boron-containing gas and hydrogen fluoride gas
Embodiments of the invention provide a method for atomic layer etching (ALE) of a substrate. According to one embodiment, the method includes providing a substrate, and exposing the substrate to hydrogen fluoride (HF) gas and a boron-containing gas to etch the substrate. According to another embodiment, the method includes providing a substrate containing a metal oxide film, exposing the substrate to 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. The exposures may be repeated at least once to further etch the metal oxide film.
1. A method of atomic layer etching (ALE), the method comprising:
providing a substrate containing a metal oxide film having a first fluorinated surface layer;
exposing the substrate to a first boron-containing gas to remove the first fluorinated surface layer from the metal oxide film;
exposing the substrate to hydrogen fluoride (HF) gas to form a second fluorinated surface layer on the metal oxide film; and
exposing the substrate to a second boron-containing gas to remove the second fluorinated surface layer from the metal oxide film.
2. The method of claim 1 , wherein the exposures to the HF gas and the second boron-containing gas are repeated at least once to further etch the metal oxide film.
3. The method of claim 1 , 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.
4. The method of claim 1 , wherein the metal oxide film is formed by oxidizing a metal layer.
5. The method of claim 1 , further comprising gas purging with an inert gas between the exposing steps.
6. The method of claim 1 , wherein the first fluorinated surface layer is formed using wet processing with aqueous HF.
7. The method of claim 1 , wherein the first and second boron-containing gases contain a boron hydride, a boron halide, a boron amide, an organo boride, or a combination thereof.
8. The method of claim 7 , wherein the first and second boron-containing gases are 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 1 , wherein the first fluorinated surface layer is formed by dry processing.
10. The method of claim 9 , wherein the dry processing includes HF gas or an organic fluorine-containing etching gas.
11. The method of claim 1 , wherein the first and second boron-containing gases contain a boron hydride, a boron amide, an organo boride, or a combination thereof.
12. The method of claim 11 , wherein the first and second boron-containing gases are selected from the group consisting of BH 3 , B(CH 3 ) 3 , and B(N(CH 3 ) 2 ) 3 .