Compositions and methods for the selective removal of silicon nitride
View Patent ↗Compositions useful for the selective removal of silicon nitride materials relative to polysilicon, silicon oxide materials and/or silicide materials from a microelectronic device having same thereon. The removal compositions include fluorosilicic acid, silicic acid, and at least one organic solvent. Typical process temperatures are less than about 100° C. and typical selectivity for nitride versus oxide etch is about 200:1 to about 2000:1. Under typical process conditions, nickel-based silicides as well as titanium and tantalum nitrides are largely unaffected, and polysilicon etch rates are less than about 1 Å min −1 .
1. A method of removing silicon nitride from a microelectronic device, said method comprising contacting the microelectronic device with a removal composition for sufficient time under sufficient conditions to at least partially remove said silicon nitride material from the microelectronic device, wherein the removal composition includes fluorosilicic acid, silicic acid, and at least one organic solvent, wherein the selectivity of silicon nitride to silicon oxide(s) in the presence of the removal composition is in a range from about 10:1 to about 7,000:1 at temperature of 40-120° C., wherein the molar ratio of fluorosilicic acid to silicic acid is in a range from about 3:1 to about 10:1.
2. The method of claim 1 , wherein said contacting comprises at least one condition selected from the group consisting of: time of from about 1 minute to about 200 minutes; temperature in a range of from about 40° C. to about 120° C.; and combinations thereof.
3. The method of claim 1 , wherein a source of silicic acid is selected from the group consisting of silica powder, alkoxysilane, and combinations thereof.
4. The method of claim 1 , wherein the at least one organic solvent comprises a species selected from the group consisting of ethylene glycol, neopentyl glycol, propylene glycol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether (DPGME), tripropylene glycol methyl ether, propylene glycol monoethyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, tripropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether (DPGBE), tripropylene glycol n-butyl ether, propylene glycol phenyl ether (phenoxy-2-propanol), and combinations thereof.
5. The method of claim 1 , wherein the removal composition further comprises at least one corrosion inhibitor, wherein the at least one corrosion inhibitor comprises at least one metal nitride corrosion inhibitor, at least one metal silicide corrosion inhibitor, or a combination of at least one metal nitride corrosion inhibitor and at least one metal silicide corrosion inhibitor.
6. The method of claim 5 , wherein the at least one metal nitride corrosion inhibitor comprises a species selected from the group consisting of ascorbic acid, propargyl alcohol, 2-butene-1,4-diol, 2-butyne-1,4-diol, dimethylglyoxime, thianaphthene, thianthrene, 2-mercaptobenzimidazole (MBI), thiosalicylic acid, benzothiazole, thianthrene-1-boronic acid, mercaptobenzothiazole, thiophene carbonitrile, L-methionine, DL-methionine, L-cysteine 3-amino-5-mercapto-1,2,4-triazole, 5-amino-1,3,4-thiadizole-2-thiol, mercaptosuccinic acid, thioctic acid, N-acetyl-L-cysteine, 2-mercapto-1-methylimidazole, 2-mercaptopyridine, 3,3′-thiodipropionic acid, L-cystine, benzotriazole-5-carboxylic acid, imidazole, iminodiacetic acid (IDA), and combinations thereof alkoxylated alkynols.
7. The method of claim 5 , wherein the at least one metal silicide corrosion inhibitor comprises a species selected from the group consisting of nitrilotris(methylene)triphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), ethylenedinitrilotetra(methylenephosphonic) acid (EDTMP), pyrophosphoric acid, salts thereof, and combinations thereof.
8. The method of claim 1 , wherein the removal composition further comprises at least one diluent.
9. The method of claim 8 , wherein the at least one diluent comprises water.
10. The method of claim 1 , wherein the contacting comprises a process selected from the group consisting of: spraying the removal composition on a surface of the microelectronic device; dipping the microelectronic device in a sufficient volume of removal composition; contacting a surface of the microelectronic device with another material that is saturated with the removal composition; and contacting the microelectronic device with a circulating removal composition.
11. The method of claim 1 , further comprising rinsing the microelectronic device with deionized water following contact with the removal composition.