Selectively etching materials
A method of selectively removing aluminium oxide or nitride material from a microelectronic substrate, the method comprising contacting the material with an aqueous etching composition comprising: an etchant comprising a source of fluoride; and a metal corrosion inhibitor; wherein the composition has a pH in the range of from 3 to 8. Aqueous etching compositions and uses are also described.
1. A method of selectively removing aluminum oxide or nitride material, the method comprising:
i) contacting the material with an aqueous etching composition comprising:
an etchant in an amount in a range of from 0.001 to 0.5 wt./wt. % based on the total weight of the composition, the etchant comprising a source of fluoride;
a pH buffering agent in an amount in a range of from 0.01 to 2.0 wt./wt. % based on the total weight of the composition;
a metal corrosion inhibitor in an amount in a range of from 0.0001 to 2.0 wt./wt. % based on the total weight of the composition; and
a cationic surfactant corrosion inhibitor or a quat metal corrosion inhibitor comprising a quaternary ammonium cation of formula (I):
wherein R′, R 2 , R 3 and R 4 are independently selected from quaternizing groups, and wherein R 4 comprises at least 8 carbon atoms,
wherein the composition has a pH in the range of from 3 to 8; and
ii) selectively removing the aluminum oxide or nitride material relative to a metal.
2. The method of claim 1 , wherein the etchant is selected from HF, ammonium fluoride and tetraalkylammonium fluorides.
3. The method of claim 1 , wherein the amount of etchant in the composition is in the range of from 0.01 to 0.1 wt./wt. % based on the total weight of the composition.
4. The method of claim 1 , wherein the metal corrosion inhibitor comprises a heterocyclic nitrogen compound.
5. The method of claim 4 , wherein the metal corrosion inhibitor comprises an optionally substituted benzotriazole.
6. The method of claim 5 , wherein the amount of optionally substituted benzotriazole corrosion inhibitor in the composition is in the range of from 0.1 wt./wt. % to 1 wt./wt. % based on the total weight of the composition.
7. The method of claim 1 , wherein the quaternizing group includes a substituted or unsubstituted alkyl, alkoxy, or aryl group.
8. The method of claim 1 , wherein the quat metal corrosion inhibitor comprises a quaternary ammonium cation of formula II:
9. The method of claim 1 , wherein R 1 comprises a substituted or unsubstituted aryl quaternizing group, and/or wherein R 2 and R 3 are independently selected from substituted or unsubstituted alkyl groups having in the range of from 1 to 5 carbon atoms.
10. The method of claim 1 , wherein the quat metal corrosion inhibitor comprises benzyldimethyldodecylammonium chloride.
11. The method of claim 1 , wherein the amount of quat metal corrosion inhibitor in the composition is in the range of from 0.001 wt./wt. % to 0.01 wt./wt. % based on the total weight of the composition.
12. The method of claim 1 , wherein the composition has a pH in the range of from 3 to 5.
13. The method of claim 1 , wherein the pH buffering agent comprises ammonium acetate.
14. The method of claim 1 , wherein the composition comprises an organic solvent selected from the group consisting of a sulfoxide, a glycol, an ether, and a carbonate ester.
15. The method of claim 1 , able to achieve one or more of the following:
an aluminum nitride etch rate of at least 50 Angstroms/minute
a tungsten etch rate of at most 4 Angstroms/minute
a cobalt etch rate of at most 4 Angstroms/minute
a low-k dielectric etch rate of at most 4 Angstroms/minute.
16. The method of claim 1 , wherein the metal is tungsten, copper, cobalt, or ruthenium.