Wet etching composition and method
The invention provides a composition and method for improving the selectivity of nitride etching versus oxide etching and can be used with conventional phosphoric acid wet etch compositions. The invention describes additives that serve to inhibit silicon, oxides, and related compounds regrowth (i.e., redeposition) on the silicon oxide surface. In certain embodiments, the invention provides certain amino-substituted aryl compounds which are bound to a tri-alkoxy silane.
1. A composition comprising the reaction product of:
(a)
(i) a compound of Formula (I)
wherein A is an aromatic ring or a heteroaromatic ring, and wherein each R 1 is the same or different and is chosen from hydrogen, hydroxyl, C 1 -C 20 alkyl, C 1 -C 20 alkylamino, phenyl, benzyl, and C 1 -C 20 alkoxy, phenoxy, and C 3 -C 8 cycloalkyl; x is 0 or 1; each y and y′ may be the same or different and is zero or is chosen from an integer of from 1 to 5; z is an integer chosen from 1, 2, or 3; m is an integer chosen from 1, 2, or 3; w is zero or an integer chosen from 1, 2, 3, or 4 and m+z=4; or
(ii) a compound of Formula (II)
(R 1 ) 3 Si-M-Si(R 1 ) 3 (II)
wherein each R 1 is the same or different and is as defined above, and -M- is chosen from —NH— or —O—;
(b) greater than 60 weight percent concentrated phosphoric acid; and
(c) a solvent comprising water
wherein the composition is a selective etching composition having a silicon nitride to silicon oxide selectivity in a range of from about 10:1 to about 7000:1.
2. The composition of claim 1 , wherein the compound of Formula (I) has the following structure:
wherein R 1 is as defined in claim 1 , and each R 2 is the same or different and is chosen from H and C 1 -C 20 alkyl.
3. The composition of claim 1 , wherein component (a) is triphenylsilanol.
4. The composition of claim 1 , wherein component (a) is p-aminophenyl trimethoxysilane.
5. The composition of claim 1 , wherein each R 1 is the same or different and is chosen from hydroxyl, C 1 -C 20 alkoxy, and C 1 -C 20 alkylamino, and y, y′, and x are zero.
6. The composition of claim 1 , wherein component (a) is a compound of Formula (I), further comprising a compound of Formula (II), wherein R 1 is C 1 -C 20 alkyl.
7. The composition of claim 1 further comprising 3-aminopropylsilane triol and/or tetramethylammonium silicate.
8. The composition of claim 1 , wherein the composition includes a fluoride compound which is chosen from HF and monofluorphosphoric acid.
9. The composition of claim 8 , wherein the fluoride compound is chosen from fluorosilicic acid; fluoroboric acid; tetramethylammonium hexafluorophosphate; ammonium fluoride; ammonium bifluoride; quaternary ammonium tetrafluoroborates and quaternary phosphonium tetrafluoroborates having the formula NR′ 4 BF 4 and PR′ 4 BF 4 , respectively, wherein R′ may be the same as or different from one another and is selected from hydrogen, straight-chained, branched, or cyclic C 1 -C 6 alkyl, and straight-chained or branched C 6 -C 10 aryl; tetrabutylammonium tetrafluoroborate (TBA-BF 4 ); and combinations thereof.
10. The compound of claim 9 , wherein the fluoride compound is chosen from cesium fluoride and potassium fluoride.
11. The composition of claim 1 , further comprising a primary, secondary, or tertiary amine, C 1 -C 6 alkanolamine, or dihydrogen phosphate salt thereof, or a nitrogen-containing heterocyclic ring, optionally substituted by with one to three groups chosen from C 1 -C 20 alkyl, C 1 -C 20 alkoxy, —CN, —NO 2 , C 1 -C 20 alkoxycarbonyl, C 1 -C 20 alkanoyloxy, C 1 -C 20 alkylsulfonyl, hydroxyl, carboxyl, halo, phenyl, benzyl, amino-C 1 -C 20 alkyl, —C 1 -C 20 alkyl-SO 3 H, —C 1 -C 20 alkyl-PO 3 H 2 , and groups of the formula —N(R 1 ) 2 .
12. The composition of claim 11 , wherein the primary, secondary, or tertiary amine is chosen from trimethylamine, triethylamine, tripropylamine, tributylamine, N,N-dimethylaniline, or N-methylaniline.
13. The composition of claim 1 , further comprising one or more water-miscible solvents which is selected from pyrrolidinones, glycols, amines, and glycol ethers.
14. The composition of claim 1 , further comprising one or more surfactants.
15. The composition of claim 1 , further comprising one or more polymers.
16. The composition of claim 1 , further comprising one or more acids.
17. The composition of claim 16 , wherein the acids are chosen from sulfuric acid, nitric acid, methanesulfonic acid, and carboxylic acids.
18. The composition of claim 1 , wherein the compound of Formula (I) is chosen from p-aminophenyl trimethoxysilane, triphenyl silanol, and 2-(4-pyridylethyl)triethoxysilane.
19. The composition of claim 1 , wherein the compound of Formula (II) is hexamethyldisiloxane.
20. A method for removing silicon nitride from a microelectronic device, said method comprising:
contacting the microelectronic device with a composition comprising:
(i) a compound of Formula (I)
wherein A is an aromatic ring or a heteroaromatic ring, and wherein each R 1 is the same or different and is chosen from hydrogen, hydroxyl, C 1 -C 20 alkyl, C 1 -C 20 alkylamino, phenyl, benzyl, and C 1 -C 20 alkoxy, phenoxy, and C 3 -C 8 cycloalkyl; x is 0 or 1; each y and y′ may be the same or different and is zero or is chosen from an integer of from 1 to 5; z is an integer chosen from 1, 2, or 3; m is an integer chosen from 1, 2, or 3; w is zero or an integer chosen from 1, 2, 3, or 4 and m+z=4; or
(ii) a compound of Formula (II)
(R 1 ) 3 Si-M-Si(R 1 ) 3 (II)
wherein each R 1 is the same or different and is as defined above, and -M- is chosen from —NH— or —O—;
(b) greater than 60 weight percent concentrated phosphoric acid; and
(c) a solvent comprising water;
and selectively removing said silicon nitride material relative to silicon oxide from the microelectronic device with a selectivity in a range of from about 10:1 to about 7000:1.