U.S. patent application number 10/601659 was filed with the patent office on 2004-02-12 for resist stripping liquid containing fluorine compound.
Invention is credited to Ikemoto, Kazuto, Ohto, Masaru.
Application Number | 20040029753 10/601659 |
Document ID | / |
Family ID | 31180091 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040029753 |
Kind Code |
A1 |
Ikemoto, Kazuto ; et
al. |
February 12, 2004 |
Resist stripping liquid containing fluorine compound
Abstract
In the present invention, the concentration of dissolved oxygen
in the resist stripping liquid is limited to 3 ppm or lower. Using
the resist stripping liquid having such a low dissolved oxygen
concentration, resist residues are removed from a substrate
containing copper and/or a copper alloy without causing the
corrosion of copper.
Inventors: |
Ikemoto, Kazuto; (Tokyo,
JP) ; Ohto, Masaru; (Tokyo, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-9889
US
|
Family ID: |
31180091 |
Appl. No.: |
10/601659 |
Filed: |
June 24, 2003 |
Current U.S.
Class: |
510/175 ; 134/2;
510/176; 510/177; 510/178 |
Current CPC
Class: |
C11D 7/08 20130101; C11D
7/3209 20130101; C09D 9/00 20130101; C11D 7/5013 20130101; C11D
7/263 20130101; C11D 7/34 20130101; G03F 7/423 20130101; C11D
7/3263 20130101; G03F 7/425 20130101; C11D 7/3281 20130101; C11D
7/261 20130101; C11D 7/3218 20130101; C11D 7/10 20130101; C11D
11/0047 20130101 |
Class at
Publication: |
510/175 ;
510/176; 510/177; 510/178; 134/2 |
International
Class: |
C23G 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2002 |
JP |
2002-184102 |
Claims
What is claimed is:
1. A resist stripping liquid comprising a fluorine compound,
wherein the concentration of dissolved oxygen in the resist
stripping liquid is 3 ppm or lower.
2. The resist stripping liquid according to claim 1, wherein the
content of the fluorine compound is 0.001 to 55% by weight of the
resist stripping liquid.
3. The resist stripping liquid according to claim 1, further
comprising a solvent.
4. The resist stripping liquid according to claim 3, wherein the
solvent is at least one compound selected from the group consisting
of ethylene glycol monoethyl ether, ethylene glycol monobutyl
ether, diethylene glycol monomethyl ether, diethylene glycol
monoethyl ether, diethylene glycol monobutyl ether, triethylene
glycol, triethylene glycol monomethyl ether, triethylene glycol
monoethyl ether, triethylene glycol monopropyl ether, triethylene
glycol monobutyl ether, triethylene glycol dimethyl ether,
propylene glycol monomethyl ether, propylene glycol monoethyl
ether, propylene glycol monobutyl ether, dipropylene glycol
monomethyl ether, dipropylene glycol monoethyl ether, dipropylene
glycol monobutyl ether, diethylene glycol dimethyl ether,
dipropylene glycol dimethyl ether, formamide, monomethylformamide,
dimethylformamide, monoethylformamide, diethylformamide, acetamide,
monomethylacetamide, dimethylacetamide, monoethylacetamide,
diethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone,
N-methylcaprolactam, methyl alcohol, ethyl alcohol, isopropanol,
ethylene glycol, propylene glycol, dimethyl sulfoxide,
dimethylsulfone, diethyl sulfone, bis(2-hydroxyethyl) sulfone,
tetramethylene sulfone, 1,3-dimethyl-2-imidazolidinone,
1,3-diethyl-2-imidazolidinone, 1,3-diisopropyl-2-imidazolidinone,
.gamma.-butyrolactone, .delta.-valerolactone, aminoethanol,
diethanolamine, triethanolamine, isopropanolamine,
1-amino-3-propanol, diisopropanolamine, triisopropanolamine,
dimethylaminoethanol, N-methylaminoethanol, diethylaminoethanol,
aminoethoxyethanol, ethylenediamine, diethylenetriamine,
triethylenetetramine, and tetraethylenepentamine
5. The resist stripping liquid according to claim 1, wherein the
fluorine compound is ammonium fluoride, acid ammonium fluoride or
hydrofluoric acid.
6. The resist stripping liquid according to claim 1, comprising
0.001 to 20% by weight of the fluorine compound, 10 to 99.999% by
weight of a solvent and 0 to 85% by weight of water.
7. A method for removing resists, which comprises a step of
bringing a substrate having resist residues thereon into contact
with the resist stripping liquid as defined in claim 1.
8. The method according to claim 7, wherein the substrate contains
copper and/or a copper alloy.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a resist stripping liquid
for use in the manufacture of semiconductor integrated circuits,
liquid crystal panels, organic EL panels, printed circuit boards,
etc., particularly, relates to a resist stripping liquid for
removing resist residues from substrates containing copper and/or a
copper alloy.
[0003] 2. Description of the Prior Art
[0004] Photoresists have been widely used in the lithographic
production of integrated circuits such as IC and LSI, display
devices such as LCD and EL devices, printed circuit boards, micro
machines, DNA chips, and micro plants.
[0005] A solution containing an amine compound has been
conventionally used as the resist stripping liquid. For example,
U.S. Pat. No. 4,276,186 discloses a mixture of N-methylpyrrolidone
and an alkanol amine, and Japanese Patent Application Laid-Open No.
4-289866 discloses an aqueous solution containing an alkanol amine,
hydroxylamine and catechol. These resist stripping liquids have
been mainly used to remove resists from a substrate containing
non-copper based materials such as aluminum or aluminum alloy
materials. Recently, copper has come to be used as low electric
resistance materials, in particular, come to be increasingly used
as the wiring materials for semiconductors such as LSI. However,
the resist stripping liquid containing the amine compound is highly
corrosive to copper, because the amine compound forms a
copper-ammine complex.
[0006] Japanese Patent Application Laid-Open Nos. 8-202052 and
11-067632 disclose resist stripping liquids capable of removing
resists at low temperatures in a short period of time, which
contain a fluorine compound in place of the amine compound. As
compared with the resist stripping liquid containing the amine
compound, the resist stripping liquid containing the fluorine
compound is far less corrosive to copper, but not sufficient for
use in the fine processing, that has recently come to be widely
used in the semiconductor production, in view of the resolution and
precision. A corrosion inhibitor such as benzotriazole and
acetylene alcohol has been conventionally used to prevent the
corrosion of copper. However, these corrosion inhibitors
unfavorably form a thin film on the copper surface. If the
formation of the thin film is prevented, the corrosion inhibitors
fail to exhibit a sufficient corrosion-inhibiting effect when used
in air under ordinary conditions.
SUMMARY OF THE INVENTION
[0007] As a result of extensive study on the corrosion of copper
due to resist stripping liquids containing a fluorine compound, the
inventors have found that a fluorine compound-containing resist
stripping liquid having its dissolved oxygen concentration limited
to 3 ppm or lower removes resists without the corrosion of copper.
The present invention has been accomplished on the basis of this
finding.
[0008] Thus, the present invention provides a resist stripping
liquid comprising a fluorine compound, wherein the concentration of
dissolved oxygen in the resist stripping liquid is 3 ppm or lower.
The dissolved oxygen concentration is preferably 1 ppm or
lower.
DETAILED DESCRIPTION OF THE INVENTION
[0009] The resist stripping liquid of the present invention
contains a fluorine compound, a solvent and/or water, and an
optional additive.
[0010] Examples of the fluorine compounds include ammonium
fluoride, acid ammonium fluoride, hydrofluoric acid, buffered
hydrofluoric acid (mixture of hydrofluoric acid and ammonium
fluoride), methylamine hydrofluoride, dimethylamine hydrofluoride,
trimethylamine hydrofluoride, ethylamine hydrofluoride,
diethylamine hydrofluoride, triethylamine hydrofluoride,
ethanolamine hydrofluoride, diethanolamine hydrofluoride,
triethanolamine hydrofluoride, isopropanolamine hydrofluoride,
diisopropanolamine hydrofluoride, triisopropanolamine
hydrofluoride, diazabicycloundecene hydrofluoride, and
diazabicyclononene hydrofluoride, with ammonium fluoride, acid
ammonium fluoride, hydrofluoric acid and buffered hydrofluoric acid
being preferred.
[0011] The concentration of the fluorine composition in the resist
stripping liquid is preferably 0.001 to 55% by weight, although not
particularly limited thereto. If less than 0.001% by weight, the
tendency of the copper corrosion is lowered, but the resist
stripping capability is also reduced.
[0012] Examples of the solvents include ethylene glycol monoethyl
ether, ethylene glycol monobutyl ether, diethylene glycol
monomethyl ether, diethylene glycol monoethyl ether, diethylene
glycol monobutyl ether, triethylene glycol, triethylene glycol
monomethyl ether, triethylene glycol monoethyl ether, triethylene
glycol monopropyl ether, triethylene glycol monobutyl ether,
triethylene glycol dimethyl ether, propylene glycol monomethyl
ether, propylene glycol monoethyl ether, propylene glycol monobutyl
ether, dipropylene glycol monomethyl ether, dipropylene glycol
monoethyl ether, dipropylene glycol monobutyl ether, diethylene
glycol dimethyl ether, dipropylene glycol dimethyl ether,
formamide, monomethylformamide, dimethylformamide,
monoethylformamide, diethylformamide, acetamide,
monomethylacetamide, dimethylacetamide, monoethylacetamide,
diethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone,
N-methylcaprolactam, methyl alcohol, ethyl alcohol, isopropanol,
ethylene glycol, propylene glycol, dimethyl sulfoxide,
dimethylsulfone, diethyl sulfone, bis(2-hydroxyethyl) sulfone,
tetramethylene sulfone, 1,3-dimethyl-2-imidazolidinone,
1,3-diethyl-2-imidazolidinone, 1,3-diisopropyl-2-imidazolidinone,
.gamma.-butyrolactone, .delta.-valerolactone, aminoethanol,
diethanolamine, triethanolamine, isopropanolamine,
1-amino-3-propanol, diisopropanolamine, triisopropanolamine,
dimethylaminoethanol, N-methylaminoethanol, diethylaminoethanol,
aminoethoxyethanol, ethylenediamine, diethylenetriamine,
triethylenetetramine, and tetraethylenepentamine. These solvents
may be used alone or in combination of two or more.
[0013] The use of the solvent makes the fluorine compound less
soluble in the resist stripping liquid. Therefore, if the solvent
is used, the resist stripping liquid preferably comprises 0.001 to
20% by weight of the fluorine compound, 10 to 99.999% by weight of
the solvent and 0 to 85% by weight of water, more preferably 0.01
to 10% by weight of the fluorine compound, 20 to 95% by weight of
the solvent and 5 to 80% by weight of water.
[0014] The corrosion of copper is considered to occur in the
mechanism in which the copper surface is oxidized by the dissolved
oxygen in the resist stripping liquid to form copper oxides, which
are then converted into more soluble compounds by the action of the
fluorine compound, thereby promoting the corrosion of copper.
[0015] Since it has been found that the corrosion of copper is
caused by the dissolved oxygen in the resist stripping liquid, the
corrosion of copper can be prevented by reducing the dissolved
oxygen concentration of the resist stripping liquid. In the present
invention, the dissolved oxygen concentration is reduced to 3 ppm
or lower, preferably 1 ppm or lower, and more preferably 0.8 ppm or
lower. The dissolved oxygen concentration can be reduced to 3 ppm
or lower by bringing the resist stripping liquid into contact with
a non-oxygen gas to replace the dissolved oxygen with the
non-oxygen gas. Such a replacement can be effected by promoting the
gas-liquid contact, for example, by bubbling the non-oxygen gas
into the resist stripping liquid or spraying the resist stripping
liquid into the non-oxygen gas. Examples of the non-oxygen gas
include nitrogen, argon and hydrogen, with nitrogen and argon being
preferred.
[0016] The resist stripping liquid of the present invention may
further contain a corrosion inhibitor or a surfactant.
[0017] Examples of the corrosion inhibitor for copper include
azoles such as benzotriazole; alkyne compounds such as acetylene
alcohol; and lower-valent sulfur compounds such as thiourea and
mercaptothiazole. In the low dissolved oxygen conditions specified
in the present invention, these compounds can exhibit their
corrosion-inhibiting effect at low concentrations. In addition, the
low dissolved oxygen conditions of the present invention enable the
use of compounds having low corrosion-inhibiting effects.
[0018] The resist stripping liquid of the present invention is most
effective for removing resists from a substrate containing copper
and/or a copper alloy. The resist removal operation is usually
conducted at room temperature to 150.degree. C. To prevent the
attack to copper and other materials, the resist removal operation
is preferably conducted at a temperature as low as possible,
particularly, at 50.degree. C. or lower. In addition, the
inhibition of the copper corrosion can be ensured by monitoring the
dissolve oxygen concentration of the resist stripping liquid during
the resist removal operation.
[0019] The substrate to be treated in the present invention may be
made of various materials such as silicon, amorphous silicon,
polysilicon and glass, and has thereon a thin film made of copper
and/or a copper alloy. The substrate may have thin films made of
semiconductor wiring materials such as silicon oxide, silicon
nitride, aluminum, aluminum alloy, gold, platinum, silver,
titanium, titanium-tungsten, titanium nitride, tungsten, tantalum,
tantalum oxide, chromium, chromium oxide, chromium alloy and
indium-tin-oxide (ITO); compound semiconductors such as
gallium-arsenic, gallium-phosphorus and indium-phosphorus; and
dielectric materials such as strontium-bismuth-tantalum.
[0020] Using the resist stripping liquid of the present invention,
semiconductor devices are produced, for example, in the following
manner. A photoresist composition is applied on a substrate having
a thin film of copper and/or a copper alloy to form a photoresist
layer, which is then patterned by exposure to light and
development. The non-masked region of the underlying film is etched
using the patterned photoresist layer as the mask. Thereafter, the
substrate is brought into contact with the resist stripping liquid
to remove the remaining resist residues. If desired, the substrate
may be subjected to ashing treatment after the etching process, and
then, the resist residues are removed using the resist stripping
liquid. If the resist residues are resistant to removal, the
substrate may be pretreated with a solvent, hydrogen peroxide or an
aqueous alkali solution. After the removal of resist residues, the
substrate may be rinsed with an organic solvent such as alcohol or
water.
[0021] The present invention will be explained in more detail by
reference to the following examples which should not be construed
to limit the scope of the present invention.
EXAMPLES 1-6 AND COMPARATIVE EXAMPLES 1-2
[0022] A 6-inch wafer comprising a silicon substrate laminated with
a copper layer, a SiN layer, a SiO.sub.2 interlaminar insulating
layer and a resist layer in this order was dry-etched to form via
hole structures. The via hole structures reached the copper layer.
Nitrogen gas was bubbled into each resist stripping liquid having
the following composition to reduce the dissolved oxygen
concentration, into which the wafer was immersed at room
temperature. After rinsed with water, the degree of resist removal
was observed under a scanning electron microscope. In comparative
examples, air was bubbled into the resist stripping liquid in place
of nitrogen gas. The etching rate of copper was also measured. The
results are shown in the following table.
1 TABLE 1 Composition Dissolved Fluorine oxygen Immersion compounds
Solvents concentration time Resist Cu Etching rate kind wt % kind
wt % Balance (ppm) (mm) removal (.ANG./min) Examples 1 NH.sub.4F 1
DMSO 39 water 0.1 15 removed 0.2 NMP 30 2 NH.sub.4F 1 DMF 69 water
0.4 15 removed 0.4 3 NH.sub.4F 0.1 MDP 88 water 0.2 30 removed 0.8
4 NH.sub.4F 1 DMAC 69 water 0.4 30 removed 0.5 HF 0.001 Comparative
Examples 1 NH.sub.4F 1 DMF 69 water 4.8 15 removed 6.4 2 NH.sub.4F
1 DMSO 39 water 3.9 15 removed 5.1 NMP 30 3 NH.sub.4F 0.1 MDP 88
water 5.7 15 removed 18.3 4 NH.sub.4F 1 DMAC 69 water 4.2 30
removed 12.5 HF 0.001 DMSO: Dimethyl sulfoxide NMP:
N-Methylpyrrolidone DMF: Dimethylformamide MDP: Dipropylene glycol
monomethyl ether DMAC: Dimethylacetamide
[0023] Using the resist stripping liquid of the present invention,
the resist residues are removed from a substrate containing copper
and/or a copper alloy without causing the corrosion of copper.
* * * * *