METHODS FOR MINIMIZING SIDEWALL DAMAGE DURING LOW K ETCH PROCESSES
Methods for minimizing sidewall damage during low k etch processes are disclosed. The methods etch the low k layers using the plasma activated vapor of an organofluorine compound having a formula selected from the group consisting of N≡C—R; (N≡C—)—(R)—(—C≡N); R x [—C═N(R z )] y ; and R (3-a) —N—H a , wherein a=1-2, x=1-2, y=1-2, z=0-1, x+z=1-3, and each R independently has the formula H a F b C c with a=0-11, b=0-11, and c=0-5.
1 . A method for minimizing sidewall damage during a low k etch process to a difference of less than 11 nm before and after a HF rinse, the method comprising the steps of:
Depositing a patterned mask layer on a low k layer, the patterned mask layer having an opening that defines an area to produce an aperture in the low k layer;
Etching the low k layer with a plasma activated vapor of a nitrogen containing etching composition to produce the aperture in the low k layer, the aperture having a first defined sidewall width, wherein the nitrogen containing etching composition comprises an organofluorine compound having a formula selected from the group consisting of N≡C—R; (N≡C—)—(R)—(—C≡N); R x [—C═N(R z )] y ; and R (3-x) —N—H x , wherein x=1-2, y=1-2, z=0-1, x+z=1-3, and each R independently has the formula H a F b C c with a=0-11, b=0-11, and c=0-5; and
removing residual polymer from the aperture to produce a second defined sidewall width, a difference between the first and second defined sidewall widths ranging between 0 nm to 11 nm.
2 . The method of claim 1 , wherein the low k layer has the formula Si w O x C y H z , wherein w ranges from 0.01 to 1, x ranges from 0.01 to 1, y ranges from 0.01 to 1, and z ranges from 0.01 to 1.
3 . The method of claim 1 , wherein the low k layer comprise pores and a dielectric constant between 2.5 and 3.0 prior to the low k etch process.
4 . The method of claim 3 , wherein the low k layer has a dielectric constant between 3.0 and 3.5 after the low k etch process.
5 . The method of claim 2 , wherein a hardness of the low k layer changes from 0 to 10 GPa after the etch process.
6 . The method of claim 1 , wherein the mask layer is a titanium nitride, amorphous carbon, photoresist, or silicon nitride layer.
7 . The method of claim 1 , wherein the difference between the first and second defined sidewall widths ranges between 0 nm to 5 nm.
8 . The method of claim 1 , wherein the aperture has an aspect ratio between approximately 1:1 and approximately 20:1 after the cleaning step.
9 . The method of claim 1 , wherein the organofluorine compound has the formula: N≡C—R wherein R has the formula H a F b C c with a=0, b=1-11, and c=1-5.
10 . The method of claim 9 , wherein the organofluorine compound is trifluoroacetonitrile (C 2 F 3 N), nonafluoropentanitrile (C 5 F 9 N), or pentafluoroallyl cyanide (C 4 F 5 N).
11 . The method of claim 1 , wherein the organofluorine compound has the formula: N≡C—R wherein R has the formula H a F b C c with a=1-11, b=1-11, and c=1-5.
12 . The method of claim 11 , wherein the organofluorine compound is difluoroacetonitrile (C 2 HF 2 N), 2,3,3,3-tetrafluoropropionitrile (C 3 HF 4 N), 2,2,3,3-tetrafluoropropionitrile, 4,4,4-Trifluorocrotononitrile, 3,3,3-Trifluoropropionitrile, or fluoroacetonitrile.
13 . The method of claim 12 , wherein the organofluorine compound is 2,3,3,3-tetrafluoropropionitrile (C 3 HF 4 N).
14 . The method of claim 12 , wherein the organofluorine compound is difluoroacetonitrile (C 2 HF 2 N).
15 . The method of claim 1 , wherein the organofluorine compound has the formula: (N≡C—)—(R)—(—C≡N), wherein R has the formula H a F b C c with a=0, b=1-11, and c=1-5.
16 . The method of claim 15 , wherein the organofluorine compound is octafluorohexane-1,6-dinitrile or 1,1-bis(trifluoromethyl)-2,2-dicyanoethylene.
17 . The method of claim 1 , wherein the organofluorine compound has the formula: (N≡C—)—(R)—(—C≡N), wherein R has the formula H a F b C c with a=1-11, b=1-11, and c=1-5.
18 . The method of claim 17 , wherein the organofluorine compound is 2-[1-(difluoromethyl)-2,2,2-trifluoroethylidene]-propanedinitrile.
19 . The method of claim 1 , wherein the organofluorine compound has the formula: R x [—C═N(R z )] y , wherein x=1-2, y=1-2, z=0-1, x+z=1-3, and each R independently has the formula H a F b C c with a=0-11, b=0-11, and c=0-5.
20 . The method of claim 19 , wherein the organofluorine compound is N,1,1,1,3,3,3-heptafluoro-propanamine, hexafluoroacetone imine (C 3 HF 6 N), or 1,1,1,6,6,6-Hexafluoro-3-azahex-3-ene.
21 . The method of claim 1 , wherein the organofluorine compound has the formula: R (3-a) —N—H a , wherein a=1-2 and R independently has the formula H a F b C c with a=1-11, b=1-11, and c=1-5.
22 . The method of claim 21 , wherein the organofluorine compound is 2,2,2-trifluoroethylamine (C 2 H 4 F 3 N), 2,2,3,3,3-pentafluoropropylamine (C 3 H 4 F 5 N), 2,2,3,3,4,4,4-heptafluorobutylamine (C 4 H 4 F 7 N), 1,1,1,3,3,3-hexafluoroisopropylamine (C 3 H 3 F 6 N), or bis(2,2,2-trifluoroethyl)amine (C 4 H 5 F 6 N).