Etchants containing filterable surfactant
View Patent ↗An improved etching and cleaning composition for semiconductor devices is provided in which the etch solution incorporates a novel surfactant comprising a combination of a linear perfluorocarboxylic acid, a cyclic amine and an aliphatic alcohol.
1. An aqueous etching composition for etching semiconductor devices and materials comprising at least one etchant selected from the group consisting of: (a) ammonium fluoride and hydrofluoric acid, (b) phosphoric acid mixtures with (a), and (c) mixtures of (b) with one or more acids selected from sulfuric acid, acetic acid, nitric acid, fluoroboric acid; and containing at least 10 ppm, based on the weight of an aqueous etching composition of a surfactant comprising:
(i) cyclic alkylamine of formula
C x H 2x+1 N or (CH 2 ) x−1 CH NH 2
wherein x is an integer of 5 to 8;
(ii) a linear perfluorocarboxylic acid of the formula
C n F 2n−1 O 2 H or C n−1 F 2n−1 COOH
wherein n is an integer of 4 to 11 and yields a perfluoroamide of the formula
C n−1 F 2n−1 CO NHCH(CH 2 ) x−1
wherein n=4 to 11 and x=5 to 8
when reacted with the cyclic alkylamine and
(iii) an aliphatic alcohol of the formula
C n H 2n+2 O, or C n H 2n+1 OH,
wherein n is an integer of 1 to 5.
2. The aqueous composition of claim 1 wherein the surfactant “ii” is an aqueous solution comprise of a blend of a cyclic alkylamine, perfluorocarboxylic acid and aliphatic alcohol and wherein the composition comprises at least 1% by weight of the cyclic alkylamine of the formula (CH 2 ) x−1 CHNH 2 , at least 1% by weight of the Perfluorocarboxylic acid of the formula C n−1 F 2n−1 COOH, and at least 10% by weight of the aliphatic alcohol of the formula C n H 2n+1 OH.
3. The aqueous composition of claim 1 wherein the surfactant “ii” comprises about 10 ppm to about 500 ppm, of a combined quantity of cyclic alkylamine of the formula (CH 2 ) x−1 CHNH 2 and the perfluorocarboxylic acid of the formula C n−1 F 2n−1 COOH, based on the weight of the etchant.
4. The aqueous composition of claim 1 wherein the cyclic alkylamine (i) is a member selected from the group consisting of cyclopentylamine, cycloheptylamine, and cyclooctylamine.
5. The aqueous composition of claim 1 wherein the linear perfluorocarboxylic acid (ii) of the formula C n−1 F 2n−1 COOH is a member selected from the group consisting of tridecafluoroheptanoic acid (perfluoroheptanoic acid), pentadecafluorooctanoic acid (perfluorooctanoic acid), heptafluorobutyric acid (perfluorobutanoic acid), and heptadecafluorononanoic acid (perfluorononanoic acid).
6. The aqueous composition of claim 1 wherein the alcohol (iii) of the formula C n H 2n+1 OH is a member selected from the group consisting of 2-propanol, 1-propanol, ethanol, methanol, and 1-butanol.
7. A composition as in claim 1 wherein the aqueous etching composition is a blend of at least one of the following aqueous etchants, up to 40% by weight of ammonium fluoride, up to 49% by weight of hydrofluoric acid, up to 86% by weight of phosphoric acid, up to 96% of sulfuric acid, up to 100% of acetic acid, up to 70% of nitric acid, up to 50% of fluoroboric acid, and the surfactant.
8. A composition as in claim 1 wherein the aqueous etching composition is a blend of up to 40% by weight of ammonium fluoride, up to 20% by weight of hydrogen fluoride, deionized water and the surfactant.
9. A composition as in claim 1 wherein the aqueous etching composition is a blend of up to 40% by weight of ammonium fluoride, up to 5% by weight of phosphoric acid, deionized water and the surfactant.
10. A composition as in claim 1 wherein the aqueous etching composition is a blend of up to 85% by weight of phosphoric acid, up to 69% by weight of nitric acid, up to 15% by weight of acetic acid, optionally up to 1% by weight of hydrofluoric acid or/and up to 5% by weight of fluoroboric acid, and the surfactant.
11. A composition as in claim 1 wherein the aqueous etching composition is a blend of up to 45% by weight of hydrofluoric acid, up to 69% by weight of nitric acid, up to 60% by weight of acetic acid, up to 90% by weight of sulfuric acid, and the surfactant.