Selective removal of metal oxide hard masks
Compositions useful for the selective etching, i.e., removal, of metal oxide hard masks such as zirconium oxide and hafnium oxide, often used as hard masks in microelectronic devices, in the presence of other materials such as polysilicon, silicon dioxide, silicon nitride, and tungsten are provided.
1. A composition comprising consisting essentially of:
a. water;
b. a fluoride compound chosen from ammonium fluoride, ammonium bifluoride, and hexafluorosilicic acid, wherein the fluoride compound comprises about 4 to about 10 percent of the composition by weight;
c. one or more acids;
d. dodecylbenzenesulfonic acid and aminopropyl silanetriol; and
e. a water-soluble component chosen from alcohols, glycols, glycol ethers, ammonium halides, and amines;
wherein said composition has a pH of about-2 to 6 and wherein the composition preferentially etches zirconium oxide and hafnium oxide compared with polysilicon, silicon dioxide, silicon nitride, and tungsten.
2. The composition of claim 1 , wherein the pH is about 0 to about 4.
3. The composition of claim 1 , wherein the pH is about 1 to about 2.
4. The composition of claim 1 , wherein the one or more acids are chosen from hydrochloric acid and sulfuric acid.
5. The composition of claim 1 , wherein the fluoride compound is hexafluorosilicic acid.
6. The composition of claim 1 , wherein the water-soluble component is chosen from a C 1 -C 4 alkanol.
7. The composition of claim 6 , wherein the C 1 -C 4 alkanol is n-butanol.
8. The composition of claim 1 , wherein the water-soluble component is chosen from ethylene glycol, propylene glycol, 1,3-propanediol, and trimethylolpropane.
9. The composition of claim 1 , wherein the water-soluble component is chosen from glycol ethers.
10. The composition of claim 9 , wherein the glycol ethers are chosen from 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, tripropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl 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, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether hexaethylene glycol monophenylether, dipropylene glycol methyl ether acetate, and tetraethylene glycol dimethyl ether.
11. The composition of claim 10 , wherein the glycol ether is diethylene glycol monomethyl ether.