Selective Wet Etchings Of Oxides
The present invention relates to a wet etching composition including a sulfonic acid, a phosphonic acid, a phosphinic acid or a mixture of any two or more thereof, and a fluoride, and to a process of selectively etching oxides relative to nitrides, high-nitrogen content silicon oxynitride, metal, silicon or silicide. The process includes providing a substrate comprising oxide and one or more of nitride, high-nitrogen content silicon oxynitride, metal, silicon or silicide in which the oxide is to be etched; applying to the substrate for a time sufficient to remove a desired quantity of oxide from the substrate the etching composition; and removing the etching composition, in which the oxide is removed selectively.
1 - 39 . (canceled)
40 . A selective wet etching composition, comprising:
from about 45 wt. % to about 80 wt. % of a sulfonic acid;
from about 0.1 wt. % to about 40 wt. % of a fluoride; and
less than about 30 wt. % of water.
41 . The etching composition of claim 40 wherein the sulfonic acid comprises a substituted or unsubstituted alkyl or aryl sulfonic acid.
42 . The etching composition of claim 41 wherein the sulfonic acid comprises methanesulfonic acid, ethanesulfonic acid, ethane disulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, heptane sulfonic acid, dodecanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, 2-hydroxyethane-sulfonic acid, alkyl phenol sulfonic acids, chlorosulfonic acid, fluorosulfonic acid, bromosulfonic acid, 1-naphthol-4-sulfonic acid, 2-bromoethanesulfonic acid, 2,4,6-trichlorobenzenesulfonic acid, phenylmethanesulfonic acid, trifluoromethanesulfonic acid, cetylsulfonic acid, dodecylsulfonic acid, 2-, 3-, or 4-nitrobenzenesulfonic acid, di-nitrobenzenesulfonic acid, trinitrobenzenesulfonic acid, benzene-1,4-disulfonic acid, methyl-4-nitrobenzenesulfonic acid, methyldichlorobenzene sulfonic acid, isomers thereof, corresponding polysulfonic acids or mixtures of any two or more thereof.
43 . The etching composition of claim 40 wherein the source of fluoride comprises HF, NH 4 F, BF 4 , PF 6 , SiF 6 2− , HF:pyridinium, quaternary ammonium or phosphonium fluoride or bifluoride, alkyl or aryl quaternary ammonium or phosphonium fluorides and mixtures of any two or more thereof.
44 . The etching composition of claim 40 further comprising an organic solvent.
45 . The etching composition of claim 44 wherein the organic solvent comprises sulfolane or one or more of an alcohol, an alkoxyalcohol or a polyether alcohol.
46 . The etching composition of claim 40 wherein the composition has a pH less than about 2.
47 . The etching composition of claim 40 wherein the composition is substantially free of added hydroxylamine, nitrate, persulfate or any combination of two or more thereof.
48 . The etching composition of claim 40 wherein the etching composition is selective for etching high oxygen content silicon oxynitride, silicon dioxide and silicate glasses over silicon nitride, high nitrogen content silicon oxynitride, titanium nitride and silicon.
49 . The etching composition of claim 48 wherein the silicon comprises one or more of amorphous silicon, polysilicon and monocrystalline silicon.
50 . The etching composition of claim 40 wherein the composition has a selectivity for etching HPCVD oxide, APCVD oxide, thermal oxide, BPTEOS oxide, TEOS oxide, PSG, BPSG, BSG, high oxygen content silicon oxynitride, SiOC and combinations of any two or more thereof relative to one or more of silicon nitride, high nitrogen content silicon oxynitride, titanium nitride, metal, polysilicon, monocrystalline silicon and metal silicides ranging from about 15,000:1 to about 200:1.
51 . The etching composition of claim 40 wherein the composition has a selectivity for etching PSG relative to CVD dichloro-silane silicon nitride ranging from about 200:1 to about 800:1, at about 23° C.
52 . The etching composition of claim 40 wherein said etching composition is characterized by an etching rate of 6% phosphorus-doped oxide (PSG) in a range from about 2000 angstroms/minute to about 15,000 angstroms/minute.
53 . The etching composition of claim 40 wherein the composition etches PSG at ambient temperature at a rate ranging from about 1500 to about 15,000 Å/min, silicon nitride at a rate ranging from about 1 to about 20 Å/min, titanium nitride at a rate ranging from about 0 to about 3 Å/min, and polysilicon at a rate ranging from about 1 to about 20 angstroms/minute.
54 . A process of selectively etching oxide relative to nitride, metal, silicon or silicide, comprising:
providing a substrate comprising oxide and one or more of a nitride, a high-nitrogen content silicon oxynitride, a metal, silicon or a silicide in which the oxide is to be etched;
applying to the substrate for a time sufficient to remove a desired quantity of oxide from the substrate an etching composition comprising:
from about 45 wt. % to about 80 wt. % of a sulfonic acid;
from about 0.1 wt. % to about 40 wt. % of a fluoride; and
less than about 30 wt. % of water; and
removing the etching composition;
wherein the oxide is removed selective to the one or more of nitride, high-nitrogen content silicon oxynitride, metal, silicon or silicide.
55 . The process of claim 54 wherein the etching composition is applied at a temperature in the range from about 15° C. to about 60° C.
56 . The process of claim 54 wherein the etching composition is removed by washing with a rinse composition comprising water and/or a solvent.
57 . The process of claim 54 wherein the oxide is removed at a rate greater than about 1500 angstroms/minute at a temperature of about 20° C.
58 . The process of claim 54 wherein the etching composition is characterized by an etching rate of 6% phosphorus-doped oxide (PSG) in a range from about 2000 angstroms/minute to about 15,000 angstroms/minute.
59 . The process of claim 54 wherein the composition has a selectivity for etching HPCVD oxide, APCVD oxide, thermal oxide, BPTEOS oxide, TEOS oxide, PSG, BPSG, BSG, high oxygen content silicon oxynitride, SiOC and combinations of any two or more thereof relative to one or more of silicon nitride, high nitrogen content silicon oxynitride, titanium nitride, metal, polysilicon, monocrystalline silicon and metal silicides ranging from about 15,000:1 to about 200:1.
60 . The process of claim 54 wherein the composition has a selectivity for etching PSG relative to CVD dichloro-silane silicon nitride ranging from about 200:1 to about 800:1, at about 23° C.
61 . The process of claim 54 wherein the composition etches PSG at ambient temperature at a rate ranging from about 1500 to about 15,000 Å/min, silicon nitride at a rate ranging from about 1 to about 20 Å/min, titanium nitride at a rate ranging from about 0 to about 3 Å/min, and polysilicon at a rate ranging from about 1 to about 20 angstroms/minute.
62 . The process of claim 54 wherein the sulfonic acid comprises a substituted or unsubstituted alkyl or aryl sulfonic acid.
63 . The process of claim 62 wherein the sulfonic acid comprises methanesulfonic acid, ethanesulfonic acid, ethane disulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, heptane sulfonic acid, dodecanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, 2-hydroxyethane-sulfonic acid, alkyl phenol sulfonic acids, chlorosulfonic acid, fluorosulfonic acid, bromosulfonic acid, 1-naphthol-4-sulfonic acid, 2-bromoethanesulfonic acid, 2,4,6-trichlorobenzenesulfonic acid, phenylmethanesulfonic acid, trifluoromethanesulfonic acid, cetylsulfonic acid, dodecylsulfonic acid, 2-, 3-, or 4-nitrobenzenesulfonic acid, di-nitrobenzenesulfonic acid, trinitrobenzenesulfonic acid, benzene-1,4-disulfonic acid, methyl-4-nitrobenzenesulfonic acid, methyldichlorobenzene sulfonic acid, isomers thereof, corresponding polysulfonic acids or mixtures of any two or more thereof.
64 . The process of claim 54 wherein the source of fluoride comprises HF, NH 4 F, BF 4 , PF 6 , SiF 6 2− , HF:pyridinium, quaternary ammonium or phosphonium fluoride, alkyl or aryl quaternary ammonium or phosphonium fluorides, or a bifluoride of any of the foregoing and mixtures of any two or more thereof.
65 . The process of claim 54 wherein the composition further comprises an organic solvent.
66 . The process of claim 65 wherein the organic solvent comprises sulfolane or one or more of an alcohol, an alkoxyalcohol or a polyether alcohol.
67 . The process of claim 54 wherein the composition has a pH less than about 2.
68 . The process of claim 54 wherein the composition is substantially free of added hydroxylamine, nitrate, persulfate or any combination of two or more thereof.
69 . The process of claim 54 wherein the etching composition is selective for etching high oxygen content silicon oxynitride, silicon dioxide and silicate glasses over silicon nitride, titanium nitride and silicon.
70 . The process of claim 69 wherein the silicon comprises one or more of amorphous silicon, polysilicon and monocrystalline silicon.
71 . The process of claim 54 wherein the composition is substantially free of added water and/or is anhydrous.
72 . The etching composition of claim 40 wherein the composition is substantially free of added water and/or is anhydrous.
73 . A selective wet etching composition, comprising:
from about 40 wt. % to about 80 wt. % of a phosphonic acid or a phosphinic acid or a mixture of any two or more thereof;
from about 0.1 wt. % to about 40 wt. % of a fluoride; and
less than about 30 wt. % of water.
74 . The etching composition of claim 73 wherein the phosphonic acid comprises a C 1 -C 10 branched or unbranched alkyl or C 6 -C 24 aryl or C 1 -C 10 branched or unbranched alkyl-substituted C 7 -C 36 aryl phosphonic acid.
75 . The etching composition of claim 73 wherein the phosphinic acid comprises a C 1 -C 10 branched or unbranched alkyl or C 6 -C 24 aryl or C 1 -C 10 branched or unbranched alkyl-substituted C 7 -C 36 aryl phosphinic acid.
76 . A process of selectively etching oxide relative to nitride, metal, silicon or silicide, comprising:
providing a substrate comprising oxide and one or more of a nitride, a high-nitrogen content silicon oxynitride, a metal, silicon or a silicide in which the oxide is to be etched;
applying to the substrate for a time sufficient to remove a desired quantity of oxide from the substrate an etching composition comprising:
from about 40 wt. % to about 80 wt. % of a phosphonic acid or a phosphinic acid or a mixture of any two or more thereof;
from about 0.1 wt. % to about 40 wt. % of a fluoride; and
less than about 30 wt. % of water; and
removing the etching composition;
wherein the oxide is removed selective to the one or more of nitride, high-nitrogen content silicon oxynitride, metal, silicon or silicide.
77 . The process of claim 76 wherein the phosphonic acid comprises a C 1 -C 10 branched or unbranched alkyl or C 6 -C 24 aryl or C 1 -C 10 branched or unbranched alkyl-substituted C 7 -C 36 aryl phosphonic acid.
78 . The process of claim 76 wherein the phosphinic acid comprises a C 1 -C 10 branched or unbranched alkyl or C 6 -C 24 aryl or C 1 -C 10 branched or unbranched alkyl-substituted C 7 -C 36 aryl phosphinic acid.