Etching of alkali metal compounds
Methods for etching alkali metal compounds are disclosed. Some embodiments of the disclosure expose an alkali metal compound to an alcohol to form a volatile metal alkoxide. Some embodiments of the disclosure expose an alkali metal compound to a β-diketone to form a volatile alkali metal β-diketonate compound. Some embodiments of the disclosure are performed in-situ after a deposition process. Some embodiments of the disclosure provide methods which selectively etch alkali metal compounds.
1. A method of etching an alkali metal compound, the method comprising exposing the alkali metal compound to an alcohol for a pulse time to form a volatile metal alkoxide and purging the volatile metal alkoxide for a purge time.
2. The method of claim 1 , wherein the alkali metal compound comprises one or more of a pure metal, a metal oxide or a metal nitride.
3. The method of claim 1 , wherein the alkali metal compound consists essentially of lithium.
4. The method of claim 1 , wherein the alcohol comprises one to six carbon atoms.
5. The method of claim 4 , wherein the alkali metal compound consists essentially of lithium.
6. The method of claim 5 , wherein the pulse time is in a range of from 0.5 sec to 60 sec and the purge time is in a range of from 0.05 sec to 5 sec.
7. The method of claim 5 , wherein the exposure and purge operations are repeated to etch a predetermined thickness of the alkali metal compound.
8. The method of claim 5 , wherein the alcohol is pulsed into a constant flow of an inert carrier gas.
9. The method of claim 1 , wherein the alcohol comprises one or more of one or more of methanol, ethanol, isopropanol or tertiary butanol.
10. The method of claim 1 , wherein the alkali metal compound is maintained at a temperature in a range of from 50° C. to 200° C.
11. The method of claim 1 , wherein the method is performed under vacuum at a pressure in a range of from 0.01 mbar to 100 mbar.
12. The method of claim 1 , wherein the alkali metal compound is exposed to a coflow of the alcohol and an inert carrier gas.
13. The method of claim 12 , wherein the inert carrier gas comprises one or more of Ar, Xe or Ne.
14. The method of claim 1 , wherein the alkali metal compound is etched at a rate in a range of 1 micron per minute to 20 microns per minute.
15. The method of claim 1 , wherein the method selectively etches the alkali metal compound relative to stainless-steel or copper materials.
16. A method of etching an alkali metal compound, the method comprising exposing the alkali metal compound to a β-diketone to form a volatile alkali metal β-diketonate compound.
17. The method of claim 16 , wherein the alkali metal compound comprises lithium.
18. The method of claim 16 , wherein the alkali metal compound consists essentially of lithium and the method further comprises oxidizing the alkali metal compound to form an alkali metal oxide prior to exposure to the β-diketone.
19. The method of claim 18 , wherein oxidizing the alkali metal compound comprises exposing the alkali metal compound to one or more of H 2 O, O 2 , O 3 or O 2 plasma.
20. The method of claim 16 , wherein the β-diketone comprises one or more of dipivaloylmethane (HDPM), hexafluoroacetylacetonate (HHFA), pivaloyltrifluoroacetone (HPTA) or trifluoroacetylacetone (HTFA).