U.S. patent application number 16/582254 was filed with the patent office on 2020-01-16 for etching composition.
The applicant listed for this patent is Fujifilm Electronic Materials U.S.A., Inc.. Invention is credited to Thomas Dory, Emil A. Kneer, Tomonori Takahashi.
Application Number | 20200020545 16/582254 |
Document ID | / |
Family ID | 54141496 |
Filed Date | 2020-01-16 |
United States Patent
Application |
20200020545 |
Kind Code |
A1 |
Dory; Thomas ; et
al. |
January 16, 2020 |
Etching Composition
Abstract
This disclosure relates to etching compositions containing 1) at
least one oxidizing agent; 2) at least one chelating agent; 3) at
least one metal corrosion inhibitor; 4) at least one organic
solvent; 5) at least one amidine base; and 6) water.
Inventors: |
Dory; Thomas; (Gilbert,
AZ) ; Kneer; Emil A.; (Mesa, AZ) ; Takahashi;
Tomonori; (Shizuoka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fujifilm Electronic Materials U.S.A., Inc. |
N. Kingstown |
RI |
US |
|
|
Family ID: |
54141496 |
Appl. No.: |
16/582254 |
Filed: |
September 25, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14659663 |
Mar 17, 2015 |
10490417 |
|
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16582254 |
|
|
|
|
61954698 |
Mar 18, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23F 1/32 20130101; C23F
1/00 20130101; H01L 21/32134 20130101; H01L 21/02057 20130101; C09K
13/06 20130101 |
International
Class: |
H01L 21/3213 20060101
H01L021/3213; H01L 21/02 20060101 H01L021/02; C09K 13/06 20060101
C09K013/06; C23F 1/32 20060101 C23F001/32; C23F 1/00 20060101
C23F001/00 |
Claims
1. An etching composition, comprising: 1) at least one oxidizing
agent comprising hydrogen peroxide, the at least one oxidizing
agent being in an amount of from about 0.1% to about 30% by weight
of the composition; 2) at least one chelating agent, the at least
one chelating agent being in an amount of from about 0.01% to about
1% by weight of the composition; 3) at least one metal corrosion
inhibitor comprising substituted or unsubstituted benzotriazole, at
the least one metal corrosion inhibitor being in an amount of from
about 0.05% to about 1% by weight of the composition; 4) at least
one organic solvent; 5) at least one amidine base, the at least one
amidine base being in an amount of from about 0.1% to about 5% by
weight of the composition; and 6) water; wherein the composition
has a pH of from about 6.5 to at most about 9.5.
2. The composition of claim 1, wherein the composition has a pH
from about 6.5 to about 9.
3. The composition of claim 1, wherein the at least one oxidizing
agent is in an amount of from about 1% to about 30% by weight of
the composition.
4. The composition of claim 1, wherein the at least one chelating
agent comprises polyaminopolycarboxylic acid.
5. The composition of claim 4, wherein the polyaminopolycarboxylic
acid is selected from the group consisting of mono- or polyalkylene
polyamine polycarboxylic acids, polyaminoalkane polycarboxylic
acids, polyaminoalkanol polycarboxylic acids, and hydroxyalkylether
polyamine polycarboxylic acids.
6. The composition of claim 5, wherein the polyaminopolycarboxylic
acid is selected from the group consisting of
butylenediaminetetraacetic acid, diethylenetriaminepentaacetic
acid, ethylenediaminetetrapropionic acid,
triethylenetetraminehexaacetic acid,
1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid,
propylenediaminetetraacetic acid, ethylenediaminetetraacetic acid,
trans-1,2-diaminocyclohexane tetraacetic acid, ethylendiamine
diacetic acid, ethylendiamine dipropionic acid,
1,6-hexamethylene-diamine-N,N,N',N'-tetraacetic acid,
N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid,
diaminopropane tetraacetic acid, iminodiacetic acid;
1,4,7,10-tetraazacyclododecane-tetraacetic acid, diaminopropanol
tetraacetic acid, and (hydroxyethyl)ethylenediaminetriacetic
acid.
7. The composition of claim 1, wherein the at least one chelating
agent is in an amount of from about 0.1% to about 1% by weight of
the composition.
8. The composition of claim 1, wherein the at least one metal
corrosion inhibitor comprises a substituted benzotriazole.
9. The composition of claim 1, wherein the at least one metal
corrosion inhibitor comprises a benzotriazole optionally
substituted by at least one substituent selected from the group
consisting of alkyl groups, aryl groups, halogen groups, amino
groups, nitro groups, alkoxy groups, and hydroxyl groups.
10. The composition of claim 1, wherein the substituted or
unsubstituted benzotriazole is selected from the group consisting
of benzotriazole, 5-aminobenzotriazole, 1-hydroxybenzotriazole,
5-phenylthiol-benzotriazole, 5-chlorobenzotriazole,
4-chlorobenzotriazole, 5-bromobenzotriazole, 4-bromobenzotriazole,
5-fluorobenzotriazole, 4-fluorobenzotriazole, naphthotriazole,
tolyltriazole, 5-phenyl-benzotriazole, 5-nitrobenzotriazole,
4-nitrobenzotriazole, 2-(5-amino-pentyl)-benzotriazole,
1-amino-benzotriazole, 5-methyl-1H-benzotriazole,
benzotriazole-5-carboxylic acid, 4-m ethylbenzotriazole,
4-ethylbenzotriazole, 5-ethylbenzotriazole, 4-propylbenzotriazole,
5-propylbenzotriazole, 4-isopropylbenzotriazole,
5-isopropylbenzotriazole, 4-n-butylbenzotriazole,
5-n-butylbenzotriazole, 4-isobutylbenzotriazole,
5-isobutylbenzotriazole, 4-pentylbenzotriazole,
5-pentylbenzotriazole, 4-hexylbenzotriazole, 5-hexylbenzotriazole,
5-methoxybenzotriazole, 5-hydroxybenzotriazole,
dihydroxypropylbenzotriazole,
1-[N,N-bis(2-ethylhexyl)aminomethyl]-benzotriazole, 5-t-butyl
benzotriazole, 5-(1',1'-dimethylpropyl)-benzotriazole,
5-(1',1',3'-trimethylbutyl)benzotriazole, 5-n-octyl benzotriazole,
and 5-(1',1',3',3'-tetramethylbutyl)benzotriazole.
11. The composition of claim 1, wherein the at least one metal
corrosion inhibitor is in an amount of from about 0.1% to about 1%
by weight of the composition.
12. The composition of claim 1, wherein the at least one organic
solvent comprises a solvent selected from the group consisting of
water soluble alcohols, water soluble ketones, water soluble
esters, and water soluble ethers.
13. The composition of claim 1, wherein the composition comprises
from about 1% to about 30% by weight of the at least one organic
solvent.
14. The composition of claim 1, wherein the at least one amidine
base comprises a compound selected from the group consisting of
substituted or unsubstituted formamidines, substituted or
unsubstituted acetamidines, substituted or unsubstituted
benzamidines, diminazen, and compounds containing an amidine group
in a fused non-aromatic ring.
15. The composition of claim 14, wherein the compound containing an
amidine group in a fused non-aromatic ring is
1,8-diazabicyclo[5.4.0]undec-7-ene or
1,5-diazabicyclo[4.3.0]non-5-ene.
16. The composition of claim 1, wherein the at least one amidine
base is in the amount of from about 0.3% to about 5% by weight of
the composition.
17. The composition of claim 1, wherein the composition comprises
from about 35% to about 98% of water.
18. A method, comprising: contacting a semiconductor substrate
containing TiN features with the composition of claim 1 to remove
the TiN features.
19. The method of claim 18, further comprising rinsing the
semiconductor substrate with a rinse solvent after the contacting
step.
20. The method of claim 19, further comprising drying the
semiconductor substrate after the rinsing step.
21. The method of claim 18, wherein the method does not
substantially remove Co, SiN, or Cu in the semiconductor substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of and claims
priority to U.S. application Ser. No. 14/659,663, filed on Mar. 17,
2015, which claims priority to U.S. Provisional Application Ser.
No. 61/954,698, filed on Mar. 18, 2014. The contents of the each of
these priority applications are hereby incorporated by reference in
their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to compositions and processes
to selectively etch titanium nitride in the presence of other
materials, such as metal conductors, barrier materials, insulator
materials, and exposed or underlying layers of copper, tungsten,
and low-k dielectric materials.
BACKGROUND
[0003] The semiconductor industry is rapidly decreasing the
dimensions and increasing the density of electronic circuitry and
electronic components in microelectronic devices, silicon chips,
liquid crystal displays, MEMS (Micro Electro Mechanical Systems),
printed wiring boards, and the like. The integrated circuits within
them are being layered or stacked with constantly decreasing
thicknesses of the insulating layer between each circuitry layer
and smaller and smaller feature sizes. As the feature sizes have
shrunk, patterns have become smaller, and device performance
parameters tighter and more robust. As a result, various issues
which heretofore could be tolerated, can no longer be tolerated or
have become more of an issue due to the smaller feature size.
[0004] In the production of advanced integrated circuits, to
minimize problems associated with the higher density and to
optimize performance, both high k and low k insulators, and
assorted barrier layer materials have been employed.
[0005] Titanium nitride (TiN) is utilized for semiconductor
devices, liquid crystal displays, MEMS (Micro Electro Mechanical
Systems), printed wiring boards and the like, and as ground layers
and cap layers for precious metal, aluminum (Al) and copper (Cu)
wiring. In semiconductor devices, it may be used as a barrier
metal, a hard mask, or a gate metal.
[0006] In the construction of devices for these applications, TiN
frequently needs to be etched. In the various types of uses and
device environments of TiN, other layers are in contact with or
otherwise exposed at the same time as the TiN is etched. Highly
selective etching of the TiN in the presence of these other
materials (e.g. metal conductors, dielectric, and hard marks) is
mandatory for device yield and long life. The etching process for
the TiN may be a plasma etching process. However, using a plasma
etching process on the TiN layer may cause damage to either or both
the gate insulating layer and the semiconductor substrate. In
addition, the etching process may remove a portion of the
semiconductor substrate by etching the gate insulating layer
exposed by the gate electrode. The electrical characteristics of
the transistor may be negatively impacted. To avoid such etching
damage, additional protective device manufacturing steps may be
employed, but at significant cost.
[0007] Wet etching methods for TiN are known. Such methods may
include use of etchants containing hydrofluoric acid in combination
with other reagents. However, the selectivity with silicon based
dielectrics and metals (e.g., Al) is not sufficient and other
exposed metals in the device may also undergo corrosion or
etching.
[0008] Hydrogen peroxide/ammonia/EDTA (ethylenediaminetetraacetic
acid) mixtures and hydrogen peroxide/phosphate mixtures have been
disclosed as means of overcoming the acidic HF based etchants.
However, the etch rates obtained are insufficient.
[0009] Thus, there is a need for TiN etching solutions that have
high etch rates, but have low etch and corrosion rates for other
semiconductor materials which are exposed or in contact with the
TiN during the etching process.
SUMMARY
[0010] The present disclosure relates to compositions and processes
for selectively etching TiN relative to metal conductor layers,
hard mask layers and low-k dielectric layers that are present in
the semiconductor device. More specifically, the present disclosure
relates to a composition and process for selectively etching
titanium nitride relative to copper, tungsten, and low-k dielectric
layers.
[0011] In one aspect, the disclosure features an etching
composition (e.g., an etching composition for selectively removing
titanium nitride) that includes:
[0012] 1) at least one oxidizing agent;
[0013] 2) at least one chelating agent;
[0014] 3) at least one metal corrosion inhibitor;
[0015] 4) at least one organic solvent;
[0016] 5) at least one amidine base; and
[0017] 6) water.
[0018] In another aspect, the disclosure features a method that
includes contacting a semiconductor substrate containing TiN
features with an etching composition disclosed herein to remove the
TiN features.
[0019] In still another aspect, the disclosure features an article
formed by the method described above, in which the article is a
semiconductor device (e.g., an integrated circuit).
[0020] In some embodiments, the etching compositions for
selectively removing titanium nitride contain:
[0021] 1) about 0.1% to about 30% by weight of at least one
oxidizing agent;
[0022] 2) about 0.01% to about 1% by weight of at least one
chelating agent;
[0023] 3) about 0.05% to about 1% by weight of at least one metal
corrosion inhibitor;
[0024] 4) about 1% to about 30% by weight of at least one organic
solvent;
[0025] 5) about 0.1 to about 5% by weight of at least one amidine
base (e.g., to adjust the pH to between about 6.5 and about 9.5);
and
[0026] 6) about 35% to about 98% water.
[0027] In some embodiments, the etching compositions for
selectively removing titanium nitride contain:
[0028] 1) about 0.1% to about 30% by weight of hydrogen
peroxide;
[0029] 2) about 0.01% to about 1% by weight of at least one
polyaminopolycarboxylic acid chelating agent;
[0030] 3) about 0.05% to about 1% by weight of at least one metal
corrosion inhibitor selected from the group consisting of
substituted and unsubstituted benzotriazoles;
[0031] 4) about 1% to about 30% by weight of at least one organic
solvent selected from the group consisting of water soluble
alcohols, water soluble ketones, water soluble esters, and water
soluble ethers;
[0032] 5) about 0.1 to about 5% by weight of at least one amidine
base (e.g., to adjust the pH to between about 6.5 and about 9.5);
and
[0033] 6) about 35% to about 98% water.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0034] As defined herein, unless otherwise noted, all percentages
expressed should be understood to be percentages by weight to the
total weight of the etching composition. Unless otherwise noted,
ambient temperature is defined to be between about 16 and about 27
degrees Celsius (.degree. C.).
[0035] As defined herein, a "water-soluble" substance (e.g., a
water-soluble alcohol, ketone, ester, or ether) refers to a
substance having a solubility of at least 5% by weight in water at
25.degree. C.
[0036] In one aspect, the disclosure features an etching
composition (e.g., an etching composition for selectively removing
titanium nitride) that includes:
[0037] 1) at least one oxidizing agent;
[0038] 2) at least one chelating agent;
[0039] 3) at least one metal corrosion inhibitor;
[0040] 4) at least one organic solvent;
[0041] 5) at least one amidine base; and
[0042] 6) water.
[0043] The etching compositions of this disclosure can contain any
oxidizing agent suitable for use in microelectronic cleaning
compositions. Examples of the oxidizing agent to be used in the
compositions of this disclosure include, but are not limited to,
peroxides (e.g., hydrogen peroxide, dialkylperoxides, urea hydrogen
peroxide), persulfonic acid (e.g., hexafluoropropanepersulfonic
acid, methanepersulfonic acid, trifluoromethanepersulfonic acid, or
p-toluenepersulfonic acid) and salts thereof, ozone, percarbonic
acids (e.g., peracetic acid) and salts thereof, perphosphoric acid
and salts thereof, persulfuric acid and salts thereof (e.g.,
ammonium persulfate or tetramethylammonium persulfate), perchloric
acid and salts thereof (e.g., ammonium perchlorate or
tetramethylammonium perchlorate), and periodic acid and salts
thereof (e.g., ammonium periodate or tetramethylammonium
periodate). These oxidizing agents can be used singly or in
combination.
[0044] In some embodiments, the etching compositions of this
disclosure include at least about 0.1% by weight (e.g., at least
about 1% by weight, at least about 5% by weight, or at least about
10% by weight) and/or at most about 30% by weight (e.g., at most
about 25% by weight, at most about 20% by weight, or at most about
15% by weight) of the oxidizing agent.
[0045] The etching compositions of this disclosure contain at least
one chelating agent, which can be, but is not limited to, a
polyaminopolycarboxylic acid. For the purposes of this disclosure,
a polyaminopolycarboxylic acid refers to a compound with a
plurality of amino groups and a plurality of carboxylic acid
groups. Suitable classes of polyaminopolycarboxylic acid chelating
agents include, but are not limited to mono- or polyalkylene
polyamine polycarboxylic acids, polyaminoalkane polycarboxyalic
acids, polyaminoalkanol polycarboxylic acids, and hydroxyalkylether
polyamine polycarboxylic acids.
[0046] Suitable polyaminopolycarboxylic acid chelating agents
include, but are not limited to, butylenediaminetetraacetic acid,
diethylenetriaminepentaacetic acid (DTPA),
ethylenediaminetetrapropionic acid, triethylenetetraminehexaacetic
acid, 1,3-diamino-2-hydroxypropane-N, N, N',N'-tetraacetic acid,
propylenediaminetetraacetic acid, ethylenediaminetetraacetic acid
(EDTA), trans-1,2-diaminocyclohexane tetraacetic acid,
ethylendiamine diacetic acid, ethylendiamine dipropionic acid,
1,6-hexamethylene-diamine-N,N,N',N'-tetraacetic acid,
N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid,
diaminopropane tetraacetic acid,
1,4,7,10-tetraazacyclododecane-tetraacetic acid, diaminopropanol
tetraacetic acid, and (hydroxyethyl)ethylene-diaminetriacetic
acid.
[0047] In some embodiments, the etching compositions of this
disclosure include at least about 0.01% by weight (e.g., at least
about 0.1% by weight, at least about 0.2% by weight, or at least
about 0.3% by weight) and/or at most about 1% by weight (e.g., at
most about 0.7% by weight, at most about 0.6% by weight, or at most
about 0.5% by weight) of the polyaminopolycarboxylic acid chelating
agent.
[0048] The etching compositions of this disclosure contain at least
one metal corrosion inhibitor selected from substituted or
unsubstituted benzotriazoles. Suitable classes of substituted
benzotriazole include, but are not limited to, benzotriazoles
substituted with alkyl groups, aryl groups, halogen groups, amino
groups, nitro groups, alkoxy groups, and hydroxyl groups.
Substituted benzotriazoles also include those fused with one or
more aryl (e.g., phenyl) or heteroaryl groups.
[0049] Suitable benzotriazoles for use as a metal corrosion
inhibitor include, but are not limited to, benzotriazole (BTA),
5-aminobenzotriazole, 1-hydroxybenzotriazole,
5-phenylthiol-benzotriazole, 5-chlorobenzotriazole,
4-chlorobenzotriazole, 5-bromobenzotriazole, 4-bromobenzotriazole,
5-fluorobenzotriazole, 4-fluorobenzotriazole, naphthotriazole,
tolyltriazole, 5-phenyl-benzotriazole, 5-nitrobenzotriazole,
4-nitrobenzotriazole, 2-(5-amino-pentyl)-benzotriazole,
1-amino-benzotriazole, 5-methyl-1H-benzotriazole,
benzotriazole-5-carboxylic acid, 4-m ethylbenzotriazole,
4-ethylbenzotriazole, 5-ethylbenzotriazole, 4-propylbenzotriazole,
5-propylbenzotriazole, 4-isopropylbenzotriazole,
5-isopropylbenzotriazole, 4-n-butylbenzotriazole,
5-n-butylbenzotriazole, 4-isobutylbenzotriazole,
5-isobutylbenzotriazole, 4-pentylbenzotriazole,
5-pentylbenzotriazole, 4-hexylbenzotriazole, 5-hexylbenzotriazole,
5-m ethoxybenzotriazole, 5-hydroxybenzotriazole,
dihydroxypropylbenzotriazole, 1-[N,
N-bis(2-ethylhexyl)aminomethyl]-benzotriazole, 5-t-butyl
benzotriazole, 5-(1',1'-dimethylpropyl)-benzotriazole,
5-(1',1',3'-trimethylbutyl)benzotriazole, 5-n-octyl benzotriazole,
and 5-(1',1',3',3'-tetramethylbutyl)benzotriazole.
[0050] In some embodiments, the etching compositions of this
disclosure include at least about 0.05% by weight (e.g., at least
about 0.1% by weight, at least about 0.2% by weight, or at least
about 0.3% by weight) and/or at most about 1% by weight (e.g., at
most about 0.7% by weight, at most about 0.6% by weight, or at most
about 0.5% by weight) of the metal corrosion inhibitor.
[0051] The etching compositions of this disclosure contain at least
one organic solvent. Preferably the organic solvent is selected
from the group consisting of water soluble alcohols, water soluble
ketones, water soluble esters, and water soluble ethers (e.g.,
glycol diethers).
[0052] Classes of water soluble alcohols include, but are not
limited to, alkane diols (including, but not limited to, alkylene
glycols), glycols, alkoxyalcohols (including but not limited to
glycol monoethers), saturated aliphatic monohydric alcohols,
unsaturated non-aromatic monohydric alcohols, and low molecular
weight alcohols containing a ring structure.
[0053] Examples of water soluble alkane diols includes, but are not
limited to, 2-methyl-1,3-propanediol, 1,3-propanediol,
2,2-dimethyl-1,3-diol, 1,4-butanediol, 1,3-butanediol,
1,2-butanediol, 2,3-butanediol, pinacol, and alkylene glycols.
[0054] Examples of water soluble alkylene glycols include, but are
not limited to, ethylene glycol, propylene glycol, diethylene
glycol, dipropylene glycol, triethylene glycol and tetraethylene
glycol.
[0055] Examples of water soluble alkoxyalcohols include, but are
not limited to, 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-butanol,
1-methoxy-2-butanol, and water soluble glycol monoethers.
[0056] Examples of water soluble glycol monoethers include, but are
not limited to, ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, ethylene glycol mono n-propyl ether, ethylene
glycol monoisopropyl ether, ethylene glycol mono n-butyl ether,
diethylene glycol monomethyl ether, diethylene glycol monoethyl
ether, diethylene glycol monobutylether, triethylene glycol
monomethyl ether, triethylene glycol monoethyl ether, triethylene
glycol monobutyl ether, 1-methoxy-2-propanol, 2-methoxy-1-propanol,
1-ethoxy-2-propanol, 2-ethoxy-1-propanol, propylene glycol
mono-n-propyl ether, dipropylene glycol monomethyl ether,
dipropylene glycol monoethyl ether, dipropylene glycol monobutyl
ether, dipropylene glycol mono-n-propyl ether, tripropylene glycol
monoethyl ether, tripropylene glycol monomethyl ether, ethylene
glycol monobenzyl ether, and diethylene glycol monobenzyl
ether.
[0057] Examples of water soluble saturated aliphatic monohydric
alcohols include, but are not limited to, methanol, ethanol,
n-propyl alcohol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl
alcohol, tert-butyl alcohol, 2-pentanol, t-pentyl alcohol, and
1-hexanol.
[0058] Examples of water soluble unsaturated non-aromatic
monohydric alcohols include, but are not limited to, allyl alcohol,
propargyl alcohol, 2-butenyl alcohol, 3-butenyl alcohol, and
4-penten-2-ol.
[0059] Examples of water soluble, low molecular weight alcohols
containing a ring structure include, but are not limited, to
tetrahydrofurfuryl alcohol, furfuryl alcohol, and
1,3-cyclopentanediol.
[0060] Examples of water soluble ketones include, but are not
limited to, acetone, cyclobutanone, cyclopentanone, diacetone
alcohol, 2-butanone, 5-hexanedione, 1,4-cyclohexanedione,
3-hydroxyacetophenone, 1,3-cyclohexanedione, and cyclohexanone.
[0061] Examples of water soluble esters include, but are not
limited to, ethyl acetate, glycol monoesters (such as ethylene
glycol monoacetate and diethyleneglycol monoacetate), and glycol
monoether monoesters (such as propylene glycol monomethyl ether
acetate, ethylene glycol monomethyl ether acetate, propylene glycol
monoethyl ether acetate, and ethylene glycol monoethyl ether
acetate).
[0062] In some embodiments, the etching compositions of this
disclosure include at least about 1% by weight (e.g., at least
about 5% by weight, at least about 8% by weight, or at least about
10% by weight) and/or at most about 30% by weight (e.g., at most
about 25% by weight, at most about 20% by weight, or at most about
15% by weight) of the organic solvent.
[0063] The etching compositions of this disclosure contain at least
one amidine base. The term amidine base in this disclosure is used
to describe a compound having as a substructural group
"N.sup.1--C.dbd.N.sup.2" with the proviso neither nitrogen is
embedded in an aromatic or pseudoaromatic ring (e.g., imidazole,
pyridine, thiazole, oxazole, or pyrimidine rings) and furthermore
is not considered an amine. Examples of suitable amidine bases
include, but are not limited to substituted or unsubstituted
formamidines, substituted or unsubstituted acetamidines (such as
methyl acetamidine and ethyl acetamidine), substituted or
unsubstituted benzamidines, diminazen, and compounds containing an
amidine group in a fused non-aromatic ring (such as
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and
1,5-diazabicyclo[4.3.0]non-5-ene (DBN)).
[0064] In some embodiments, the etching compositions of this
disclosure include at least about 0.1% by weight (e.g., at least
about 0.3% by weight, at least about 0.5% by weight, or at least
about 0.7% by weight) and/or at most about 5% by weight (e.g., at
most about 3% by weight, at most about 2% by weight, or at most
about 1% by weight) of the amidine base.
[0065] The etching compositions of the present disclosure further
include water. Preferably, the water is de-ionized and ultra-pure,
contains no organic contaminants and has a minimum resistivity of
about 4 to about 17 mega Ohms. More preferably, the resistivity of
the water is at least about 17 mega Ohms.
[0066] In some embodiments, the etching compositions of this
disclosure include at least about 35% by weight (e.g., at least
about 45% by weight, at least about 50% by weight, or at least
about 55% by weight) and/or at most about 98% by weight (e.g., at
most about 95% by weight, at most about 85% by weight, or at most
about 70% by weight) of water.
[0067] In some embodiments, the compositions of this disclosure can
have a pH of at least about 6.5 (e.g., at least about 7, at least
about 7.5, or at least about 8) and/or at most about 9.5 (e.g., at
most about 9, at most about 8.5, or at most about 8). Without
wishing to be bound by theory, it is believed that an etching
composition having a pH lower than 6.5 would significantly increase
cobalt etch rate and reduce TiN etch rate, and an etching
composition having a pH higher than 9.5 would result in increased
decomposition of the oxidizing agent (e.g., hydrogen peroxide) and
significantly increased corrosion to tungsten. In order to obtain
the desired pH, the relative concentrations of the
polyaminopolycarboxylic acid, the benzotriazole (or its
derivative), and the amidine base may be adjusted.
[0068] In addition, in some embodiments, the etching compositions
of the present disclosure may contain additives such as, additional
pH adjusting agents, additional corrosion inhibitors, surfactants,
additional organic solvents, biocides, and defoaming agents as
optional components.
[0069] Examples of suitable defoaming agents include polysiloxane
defoamers (e.g., polydimethylsiloxane), polyethylene glycol methyl
ether polymers, ethylene oxide/propylene oxide copolymers, and
glycidyl ether capped acetylenic diol ethoxylates (such as those
described in U.S. Pat. No. 6,717,019, herein incorporated by
reference). Optional surfactants may be cationic, anionic, nonionic
or amphoteric.
[0070] In some embodiments, the etching compositions of the present
disclosure may specifically exclude one or more of the additive
components, in any combination, if more than one. Such components
are selected from the group consisting of oxygen scavengers,
quaternary ammonium salts, including quaternary ammonium
hydroxides, amines, alkaline bases (such as NaOH, KOH, and LiOH),
surfactants other than a defoamer, a defoamer, fluoride containing
compounds, abrasives, hydroxycarboxylic acids, carboxylic and
polycarboxylic acids lacking amino groups, buffering agents, and
non-azole corrosion inhibitors.
[0071] The etching compositions of this disclosure may be prepared
by simply mixing the components together, or may be prepared by
blending two compositions in a kit. The first composition in the
kit can be an aqueous solution of an oxidizing agent (e.g.,
hydrogen peroxide). The second composition in the kit can contain
remaining components of the etching compositions of this disclosure
at predetermined ratios in a concentrated form such that the
blending of the two compositions will yield a desired composition
of the disclosure.
[0072] In some embodiments, the second composition of the kit
contains:
[0073] 1) about 0.1% to about 8% by weight of at least one
chelating agent (e.g., at least one polyaminopolycarboxylic acid
chelating agent);
[0074] 2) about 0.4% to about 8% by weight of at least one metal
corrosion inhibitor (e.g., at least one substituted or
unsubstituted benzotriazole);
[0075] 3) about 40% to about 90% by weight of at least one organic
solvent (e.g., at least one organic solvent selected from the group
consisting of water soluble alcohols, water soluble ketones, water
soluble esters, and water soluble ethers);
[0076] 4) about 1.0% to about 7% by weight of an amidine base;
and
[0077] 5) about 5% to about 15% water.
[0078] In some embodiments, the second composition of the kit
contains:
[0079] 1) about 0.1% to about 8% by weight of at least one
chelating agent (e.g., at least one polyaminopolycarboxylic acid
chelating agent);
[0080] 2) about 0.4% to about 8% by weight of at least one metal
corrosion inhibitor (e.g., at least one substituted or
unsubstituted benzotriazole);
[0081] 3) about 5% to about 90% by weight of at least one organic
solvent (e.g., at least one organic solvent selected from the group
consisting of water soluble alcohols, water soluble ketones, water
soluble esters, and water soluble ethers);
[0082] 4) about 1.0% to about 7% by weight of an amidine base;
and
[0083] 5) about 5% to about 50% water.
[0084] Alternatively, the etching compositions of this disclosure
may be prepared by blending three compositions in a kit. In such
embodiments, the first composition can include the oxidizing agent
in the form of an aqueous concentrate, the second composition can
include water only, and the third composition can include all of
the remaining components of the etching compositions of this
disclosure at predetermined ratios.
[0085] For example, a 100 g sample of a composition of this
disclosure could be made by blending 87.75 g of a first composition
containing 20% hydrogen peroxide with 12.25 g of a second
composition containing 81% EGBE, 2% 5-methylbenzotriazole, 2.0%
diethylenetriaminepentaacetic acid, 5% DBU, and 10% water.
Alternatively, the same composition could be prepared by blending
of 56.27 g of 31.1% hydrogen peroxide, 31.48 g of water and 12.25 g
of a composition of 81% EGBE, 2% 5-methylbenzotriazole, 2.0%
diethylenetriaminepentaacetic acid, 5% DBU, and 10% water.
[0086] One embodiment of the present disclosure is a method of
etching a semiconductor substrate containing TiN features that
includes contacting a semiconductor substrate containing TiN
features with an etching composition of this disclosure to remove
the TiN features. The method can further include rinsing the
semiconductor substrate with a rinse solvent after the contacting
step and/or drying the semiconductor substrate after the rinsing
step. In some embodiments, the method does not substantially remove
Co, SiN, or Cu in the semiconductor substrate. For example, the
method does not remove more than about 5% by weight (e.g., more
than about 3% by weight or more than about 1% by weight) of Co,
SiN, or Cu in the semiconductor substrate.
[0087] In some embodiments, the etching method includes the steps
of:
(A) providing a semiconductor substrate containing TiN features;
(B) contacting the semiconductor substrate with an etching
composition described herein; (C) rinsing the semiconductor
substrate with one or more suitable rinse solvents; and (D)
optionally, drying the semiconductor substrate (e.g., by any
suitable means that removes the rinse solvent and does not
compromise the integrity of said semiconductor substrate).
[0088] In some embodiments, the etching method further includes
forming a semiconductor device (e.g., an integrated circuit device
such as a semiconductor chip) from the semiconductor substrate
obtained by the method described above.
[0089] The semiconductor substrates containing TiN features to be
etched in this method can contain organic and organometallic
residues, and additionally, a range of metal oxides that may also
be removed during the etching process.
[0090] Semiconductor substrates typically are constructed of
silicon, silicon germanium, Group III-V compounds like GaAs, or any
combination thereof. The semiconductor substrates may additionally
contain exposed integrated circuit structures such as interconnect
features like metal lines and dielectric materials. Metals and
metal alloys used for interconnect features include, but are not
limited to, aluminum, aluminum alloyed with copper, copper,
titanium, tantalum, cobalt, silicon, titanium nitride, tantalum
nitride, and tungsten. The semiconductor substrate may also contain
layers of interlayer dielectrics, silicon oxide, silicon nitride,
silicon carbide, titanium oxide, and carbon doped silicon
oxides.
[0091] The semiconductor substrate can be contacted with the
etching composition by any suitable method, such as placing the
etching composition into a tank and immersing and/or submerging the
semiconductor substrate into the etching composition, spraying the
etching composition onto the semiconductor substrate, streaming the
etching composition onto the semiconductor substrate, or any
combinations thereof. In some embodiments, the semiconductor
substrate is immersed into the etching composition.
[0092] The etching compositions of the present disclosure may be
effectively used up to a temperature of about 85.degree. C. In some
embodiments, the etching compositions can be used from about
20.degree. C. to about 80.degree. C. In some embodiments, the
etching compositions can be employed in the temperature range from
about 55.degree. C. to about 65.degree. C. In some embodiments, a
temperature range of about 60.degree. C. to about 65.degree. C. is
employed. The etch rate of TiN increases with temperature in this
range, thus processes with higher temperature can be run for
shorter times and lower temperatures require longer etching
times.
[0093] Etching times can vary over a wide range depending on the
particular etching method, thickness and temperature employed. When
etching in an immersion batch type process, a suitable time range
is, for example, up to about 10 minutes. In some embodiments, a
range for a batch type process is from about 1 minute to about 7
minutes. In some embodiments, a time range for a batch type process
is from about 1 minute to about 5 minutes. In some embodiments, a
time range for a batch type etching process is from about 2 minutes
to about 4 minutes.
[0094] Etching times for a single wafer process may range from
about 30 seconds to about 5 minutes. In some embodiments, an
etching time for a single wafer process may range from about 30
seconds to about 4 minutes. In some embodiments, an etching time
for a single wafer process may range from about 1 minute to about 3
minutes. In some embodiments, an etching time for a single wafer
process may range from about 1 minute to about 2 minutes.
[0095] To further promote the etching ability of the etching
composition of the present disclosure, mechanical agitation means
may be employed. Examples of suitable agitation means include
circulation of the etching composition over the substrate,
streaming or spraying the etching composition over the substrate,
and ultrasonic or megasonic agitation during the etching process.
The orientation of the semiconductor substrate relative to the
ground may be at any angle. Horizontal or vertical orientations are
preferred.
[0096] Subsequent to the etching, the semiconductor substrate is
rinsed with a suitable rinse solvent for about 5 seconds up to
about 5 minutes with or without agitation means. Multiple rinse
steps employing different rinse solvents may be employed. Examples
of suitable rinse solvents include, but are not limited to,
deionized (DI) water, methanol, ethanol, isopropyl alcohol,
N-methylpyrrolidinone, gamma-butyrolactone, dimethyl sulfoxide,
ethyl lactate and propylene glycol monomethyl ether acetate.
Alternatively, or in addition, aqueous rinses with pH>8 (such as
dilute aqueous ammonium hydroxide) may be employed. Examples of
rinse solvents include, but are not limited to, dilute aqueous
ammonium hydroxide, DI water, methanol, ethanol and isopropyl
alcohol. In some embodiments, the rinse solvents are dilute aqueous
ammonium hydroxide, DI water and isopropyl alcohol. In some
embodiments, the rinse solvents are dilute aqueous ammonium
hydroxide and DI water. The solvent may be applied using means
similar to that used in applying an etching composition described
herein. The etching composition may have been removed from the
semiconductor substrate prior to the start of the rinsing step or
it may still be in contact with the semiconductor substrate at the
start of the rinsing step. In some embodiments, the temperature
employed in the rinsing step is between 16.degree. C. and
27.degree. C.
[0097] Optionally, the semiconductor substrate is dried after the
rinsing step. Any suitable drying means known in the art may be
employed. Examples of suitable drying means include spin drying,
flowing a dry gas across the semiconductor substrate, or heating
the semiconductor substrate with a heating means such as a hotplate
or infrared lamp, Maragoni drying, rotagoni drying, IPA drying or
any combinations thereof. Drying times will be dependent on the
specific method employed but are typically on the order of 30
seconds up to several minutes.
EXAMPLES
[0098] The present disclosure is illustrated in more detail with
reference to the following examples, which are for illustrative
purposes and should not be construed as limiting the scope of the
present disclosure. Any percentages listed are by weight (wt %)
unless otherwise specified. Controlled stirring during testing was
done with a 1 inch stirring bar at 300 rpm unless otherwise
noted.
General Procedure 1
Formulation Blending
[0099] Sample etching compositions were prepared using commercially
available reagent grade or electronics grade high purity
ingredients. All test samples were prepared at 200 gram test size
individually in 250 mL HDPE bottles using the same ingredients with
the same order of addition. To the 250 mL bottle, each sample was
prepared by addition by weight of 1) ethylene glycol butyl ether
co-solvent, 2) 5-MBTA corrosion inhibitor, 3) .about.95% of total
required ultra-pure deionized water, 4) hydrogen peroxide (31%),
and 5) DTPA. The sample was stirred using a 1'' stir bar at 325 rpm
in the 250 mL HDPE bottle to achieve full solubility of all
components at 20.degree. C. Once fully blended, the sample was
transferred from the 250 mL HDPE bottle to a 600 mL glass beaker,
placed on a hot plate, and heated to the target temperature
(65.degree. C.). During this heating period and pH adjustment
stage, the 600 mL glass beaker was sealed to prevent evaporative
loss using a flexible Parafilm.RTM. cover. The 600 mL glass beaker
containing approximately 190 grams of sample solution was stirred
continuously while heating using a 1'' stir bar at 400 rpm. A
pre-calibrated, standard epoxy body pH probe was then placed into
the sample solution while stirring, and pH response of the probe
was allowed to equilibrate to temperature. At that point, the base
pH-adjustor was incrementally added by volumetric pipette while the
pH was monitored until the target pH was reached at 65.degree. C.
Once the target pH was reached, the final addition of remaining DI
water was used to bring the final test sample weight to exactly 200
g. The weight of added DI water and base adjustor were calculated
and the total amounts of all components were recorded in the data
record in weight percent. The temperature was measured during the
tests using pre-calibrated Teflon coated glass thermometers to
insure the temperature was within .+-.1 degree Celsius of the
target during testing and pH adjustments at temperature. Later test
sample blends would be made in the same addition order at room
temperature as needed once the precise amounts of pH adjusting base
were known from the 65.degree. C. pH adjustment evaluations and
were done in 200 g or 400 g batch sizes.
General Procedure 2
Materials and Methods
[0100] Blanket film etch rate measurements on films were carried
out using commercially available unpatterned 300 mm diameter wafers
that were diced into 0.5''.times.0.5'' test coupons for evaluation.
Primary blanket film materials used for testing include 1)
unalloyed cobalt metal film of about 200 .ANG. thickness deposited
on a silicon substrate, 2) unalloyed copper metal film of about 800
.ANG. thickness deposited on a silicon substrate, 3) titanium
nitride film of about 200 .ANG. thickness deposited on 1000 .ANG.
SiO.sub.2 on a silicon substrate, and 4) blanket silicon nitride
film of either 700 or 1350 .ANG. thickness deposited on a silicon
substrate. Additional blanket materials evaluated include ILD 1 and
ILD 2 [proprietary interlayer low k dielectrics] of 1000 or 2500
.ANG. thickness on SiO.sub.2 on a silicon substrate.
[0101] The blanket film test coupons were measured for
pre-treatment and post-treatment thickness to determine blanket
film etch rates. For the cobalt and copper metal blanket films, the
film thickness was measured by sheet resistance using a CDE Resmap
273 4-point probe. For the SiN, TiN, and ILD (dielectric films),
the film thicknesses were measured pre-treatment and post-treatment
by Ellipsometry using a Woollam M-2000X.
[0102] Patterned test coupons were evaluated for etching and
materials compatibility in the test solutions prepared by General
Procedure 1 according to the procedures described in General
Procedure 3.
[0103] Two types of patterned wafers were evaluated for materials
compatibility and/or etching response. For materials compatibility,
a chemical mechanically polished 300 mm wafer consisting of
patterned cobalt metal inlayed into an ILD (dielectric pattern) was
used to evaluate cobalt and ILD compatibility for the test
formulations. The post-treatment test coupons were then subjected
to evaluation by scanning electron microscopy (SEM). The SEM images
from the post treatment coupon were compared to a previously taken
pre-treatment SEM image set to evaluate materials compatibility and
etching response of each test formulation with the patterned test
device features.
General Procedure 3
Etching Evaluation with Beaker Test
[0104] All blanket film etch rate and patterned coupon etch testing
was carried out in a 65.degree. C. heated 600 mL glass beaker
containing 200 g of a sample solution with continuous stirring at
250 rpm, with the Parafilm.RTM. cover in place at all times to
minimize evaporative losses. All blanket or patterned test coupons
having either a pattern or a blanket metal or dielectric film
exposed on one side to the sample solution were diced by diamond
scribe into 0.5''.times.0.5'' square test coupon size for beaker
scale testing. Each individual test coupon was held into position
using a single 4'' long, locking plastic tweezers clip. The test
coupon, held on one edge by the locking tweezers clip, was
suspended into the 600 mL glass beaker and immersed into the 200 g
test solution while the solution was heated at 65.degree. C. and
stirred continuously at 250 rpm. Immediately after each sample
coupon was placed into the heated and stirred solution, the top of
the 600 mL glass beaker was covered and resealed with
Parafilm.RTM.. The test coupons were held static in the stirred,
heated solution until the treatment time (as described in General
Procedures 3A and 3B) had elapsed. After the treatment time in the
test solution had elapsed, the sample coupons were immediately
removed from the 600 mL glass beaker and rinsed according to
General Procedure 3A (blanket test coupons) or General Procedure 3B
(patterned coupons). After the final DI rinse step, all test
coupons were subject to a filtered nitrogen gas blow off step using
a hand held nitrogen gas blower which forcefully removed all traces
of DI water to produce a final dry sample for test
measurements.
General Procedure 3A (Blanket Test Coupons)
[0105] Immediately after a treatment time of 10 minutes according
to General Procedure 3, the coupon was immersed in a 1000 mL volume
of ultra-high purity deionized (DI) water with .about.1 liter/min
overflow rate at 20.degree. C. for 30 seconds and then for an
additional 30 seconds with mild agitation. The processing was
completed according to General Procedure 3.
General Procedure 3B (Patterned Test Coupons)
[0106] Immediately after a treatment time of 3 or 20 minutes
(depending on the experiment) the patterned test coupon was
immersed in a 1000 mL volume of ultra-high purity deionized water
with .about.1 liter/min overflow rate at 20.degree. C. for 30
seconds with mild agitation to affect an initial DI water rinse
step. The patterned test coupons were removed from the DI water
rinse and immediately placed into a 1000 ml volume of dilute
NH.sub.4OH (.about.0.3 wt %) for 30 seconds with mild agitation,
followed by a final 30 second rinse in the 1000 mL DI water
overflow rinse. The processing was completed according to General
Procedure 3.
Examples 1 and 2
[0107] The formulations in Table 1 were used to etch TiN according
to General Procedures 3 and 3A.
[0108] In order for the compositions to be appropriate for use in
the manufacturing process, several conditions need to be
simultaneously met. These conditions are a) having a TiN etch
rate>100 .ANG./minute; b) having a Co etch rate of <1
.ANG./minute; c) maintaining compatibility with other materials
exposed to the etchant when etching TiN, and d) having shelf life
stability in order to maintain a), b), and c) over time. It is
preferred that the etch time be 3 minutes or less in manufacturing.
Table 1 summarizes the ingredients and their amounts used in
Formulation Examples 1 and 2 (i.e., FE-1 and FE-2). The results of
etching experiments employing Formulation Examples 1 and 2 with
various materials are reported in Table 2.
TABLE-US-00001 TABLE 1 WATER POLYAMINO- SOLUBLE POLY- FORM. ORGANIC
CARBOXYLIC 31.1% H.sub.2O EX. # SOLVENT TRIAZOLE ACID AMIDINE
H.sub.2O.sub.2 ADDED FE-1 EGBE (40.00 g) 5MBTA DTPA (1.00 g) DBU
(2.66 g) 153.34 g 201.12 g (0.88 g) FE-2 EGBE (40.00 g) 5MBTA DTPA
(1.00 g) DBN (2.05 g) 153.34 g 201.73 g (0.88 g) EGBE = ethylene
glycol monobutyl ether; 5MBTA = 5-methyl benzotriazole DTPA =
diethylenetriaminepentaacetic acid; DBU =
1,8-diazabicyclo[5.4.0]undec-7-ene; DBN =
1,5-diazabicyclo[4.3.0]non-5-ene
TABLE-US-00002 TABLE 2 EX. # 1 2 Form. Ex. # FE-1 FE-2 TiN etch
rate* 206 .+-. 3.2 301 .+-. 32.3 Cobalt etch rate* 0.16 0.16 SiN
etch rate* 0.31 .+-. 0.30 0.44 .+-. 0.06 ILD 1 0.0 0.40 .+-. 0.24
ILD 2 0.30 .+-. 0.42 1.27 .+-. 0.60 Cu etch rate* 1.45 1.45 pH 8.12
8.11 pH (aged**) 7.35 7.51 *angstroms/minute **aged 18 hours at
60.degree. C.
[0109] The results in Table 2 show that the etching compositions of
this disclosure have high TiN etch rates, low Co etch rates, and
maintain compatibility with SiN, ILD1, ILD2, and Cu films. When the
etchant is aged at 60.degree. C. for 18 hours, there is a drop in
pH, although the etching results were similar.
Examples 3-4 and Comparative Examples CE-1-CE-4
[0110] The compositions in Table 3 were used to study the effect of
pH on the TiN, Co, SiN, and Cu etch rates. The compositions were
essentially the same except for the amount of DBU added to adjust
the pH, with the corresponding amount of water removed. The etching
was carried out according to General Procedures 3 and 3A. The
results are shown in Table 4.
TABLE-US-00003 TABLE 3 WATER POLYAMINO- SOLUBLE POLY- FORM. ORGANIC
CARBOXYLIC 31.1% H.sub.2O EX. # SOLVENT TRIAZOLE ACID AMIDINE
H.sub.2O.sub.2 ADDED pH CFE-1 EGBE 5MBTA DTPA (1.00 g) DBU 153.34 g
202.3 g 4.00 (40.00 g) (0.88 g) (1.75 g) CFE-2 EGBE 5MBTA DTPA
(1.00 g) DBU 153.34 g 201.63 g 5.00 (40.00 g) (0.88 g) (2.15 g)
CFE-3 EGBE 5MBTA DTPA (1.00 g) DBU 153.34 g 201.54 g 5.50 (40.00 g)
(0.88 g) (2.24 g) CFE-4 EGBE 5MBTA DTPA (1.00 g) DBU 153.34 g 201.5
g 6.00 (40.00 g) (0.88 g) (2.28 g) FE-3 EGBE 5MBTA DTPA (1.00 g)
DBU 153.34 g 201.48 g 6.50 (40.00 g) (0.88 g) (2.30 g) FE-4 EGBE
5MBTA DTPA (1.00 g) DBU 153.34 g 201.12 g 8.2-8.3 (40.00 g) (0.88
g) (2.66 g) EGBE = ethylene glycol monobutyl ether DTPA =
diethylenetriaminepentaacetic acid 5MBTA = 5-methyl benzotriazole
DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene
TABLE-US-00004 TABLE 4 Cobalt FORM. TiN etch etch SiN etch Cu etch
Ex. # EX. # rate* rate* rate* rate* pH CE-1 CFE-1 57.1 .+-. 5.29
28.73 0 27.8 4 CE-2 CFE-2 40.9 .+-. 0.3 29.47 0 1.86 5 CE-3 CFE-3
53.3 .+-. 0.2 7.57 0.37 1.39 5.5 CE-4 CFE-4 86.4 .+-. 3.3 1.01 not
1.49 6 measured 3 FE-3 107.8 .+-. 2.9 0.22 not 1.35 6.5 measured 4
FE-4 206 .+-. 9 0.3 0.6 1.4 8.2-8.3 *angstroms/minute
[0111] The data in Table 4 shows that the pH plays an important
role in the etching of the TiN and Co Films. As the pH drops, the
TiN etch rate drops, and the Co etch rate increases. Only at a pH
of above about 6.5 are the criteria a) and b) above simultaneously
met. Considering the pH drop noted with aging, and the increase in
TiN etch rate with increasing pH. In some embodiments, the pH is at
least above about 7. In some embodiments, the pH is at least above
about 7.5. In some embodiments, the pH is at least above about
8.
Examples 5-6 and Comparative Examples CE-5 to CE-9
[0112] The formulations in Table 5 containing either an amidine or
an amine compound as a comparative were employed to conduct an
aging study. TiN and Co films were etched according to General
Procedures 3 and 3A with the compositions after aging at 60.degree.
C. for 120 hours. The results are shown in Table 6.
TABLE-US-00005 TABLE 5 WATER POLYAMINO- SOLUBLE POLY- FORM. ORGANIC
CARBOXYLIC 30.0% H.sub.2O EX. # SOLVENT TRIAZOLE ACID BASE
H.sub.2O.sub.2 ADDED FE-5 EGBE 5MBTA DTPA (0.50 g) DBU (1.04 g)
33.67 g 131.35 g (20.00 g) (0.44 g) CFE-5 EGBE 5MBTA DTPA (0.50 g)
ethanolamine 33.67 g 131.95 g (20.00 g) (0.44 g) (0.44 g) CFE-6
EGBE 5MBTA DTPA (0.50 g) diethylamine 33.67 g 131.74 g (20.00 g)
(0.44 g) (0.65 g) CFE-7 EGBE 5MBTA DTPA (0.50 g) triethylamine
33.67 g 131.67 g (20.00 g) (0.44 g) (0.72 g) FE-6 EGBE 5MBTA DTPA
(0.50 g) DBN (0.84 g) 33.67 g 131.55 g (20.00 g) (0.44 g) CFE-8
EGBE 5MBTA DTPA (0.50 g) diethanolamine 33.67 g 131.13 g (20.00 g)
(0.44 g) (1.26 g) CFE-9 EGBE 5MBTA DTPA (0.50 g) triethanolamine
33.67 g 129.39 g (20.00 g) (0.44 g) (3.00 g) DBU =
1,8-diazabicyclo[5.4.0]undec-7-ene DBN =
1,5-diazabicyclo[4.3.0]non-5-ene DTPA =
diethylenetriaminepentaacetic acid 5MBTA = 5-methyl benzotriazole
EGBE = ethylene glycol monobutyl ether
TABLE-US-00006 TABLE 6 FORM. TiN Cobalt pH EX. # EX. # etch rate*
etch rate* pH (aged) 5 FE-5 124.7 0.10 8.19 5.82 CE-5 CFE-5 44.0
>20 8.13 4.55 CE-6 CFE-6 21.1 >20 8.16 4.50 CE-7 CFE-7 not
measured >20 8.10 5.38 6 FE-6 100.45 0.07 8.17 6.29 CE-8 CFE-8
not measured >20 8.14 4.25 CE-9 CFE-9 not measured >20 8.12
5.03 *angstroms/minute after aging at 60.degree. C. for 120
hours
[0113] The data shows that conventional amines employed in the
compositions to control pH do not have the shelf life stability
that the amidine bases in the compositions of this disclosure do.
The pH of Comparative Formulations CFE-5, 6, 7, 8, and 9 dropped
from over 8 to less than pH 5.4, whereas Formulations FE-5 and FE-6
maintained a pH>5.8. Furthermore, Formulations FE-5 and FE-6
still yielded a TiN etch rate>100 .ANG./minute and a Co etch
rate of <1 .ANG./minute, while the comparative examples had a Co
etch rate of >20 .ANG./minute and a TiN etch rate of <100
.ANG./minute.
Examples 7 and 8
[0114] Patterned wafers (as described in General Procedure 2) were
etched for 3 minutes according to General Procedures 3 and 3B using
Formulation Examples FE-3 (Example 7) and FE-4 (Example 8). Clean
etching and materials compatibility was confirmed by SEM imaging.
SEM images demonstrate a high titanium nitride etch rate with
compatibility to copper, cobalt, silicon nitride and low-k ILD
films. Etch rates of copper, cobalt, silicon nitride and low-k ILD
films were consistent with the blanket film etch rates.
Examples 9 and 10
[0115] The compositions in Table 7 were used to study the effect of
hydrogen peroxide content on the TiN, Co, SiN, and ILD, Cu etch
rates. The compositions were essentially the same except for the
amount of hydrogen peroxide added, with the corresponding amount of
water removed. The etching was carried out according to General
Procedures 3 and 3A. The results are shown in Table 8.
TABLE-US-00007 TABLE 7 WATER POLYAMINO- SOLUBLE POLY- FORM. ORGANIC
CARBOXYLIC 30.0% H.sub.2O EX. # SOLVENT TRIAZOLE ACID AMIDINE
H.sub.2O.sub.2 ADDED FE-7 EGBE 5MBTA DTPA (0.50 g) DBU 33.33 g
144.73 g (20.00 g) (0.44 g) (1.00 g) FE-8 EGBE 5MBTA DTPA (0.50 g)
DBU 116.67 g 61.39 g (20.00 g) (0.44 g) (1.00 g)
TABLE-US-00008 TABLE 8 EX. # 9 10 Form. Ex. # FE-7 FE-8 TiN etch
rate* 114.0 .+-. 4.0 212.5 .+-. 1.8 Cobalt etch rate* 0.2 .+-. 0.04
0.24 .+-. 0.02 SiN etch rate* 0.58 .+-. 0.17 0.39 .+-. 0.07 ILD 1
0.24 .+-. 0.07 0.58 .+-. 0.08 ILD 2 0.53 .+-. 0.25 0 Cu etch rate*
0.8 .+-. 0.54 1.90 .+-. 0.06 pH 7.85 7.4-7.5
[0116] Although some of the increase in etch rate may be due to a
difference in pH, it is clear that an increase in the hydrogen
peroxide content increased the TiN etch rate with only small
effects on the etch rate of other materials except Cu.
Formulation Examples FE-9 to FE-18
[0117] The compositions of the disclosure are further exemplified
by Formulation Examples FE-9 to FE18 as shown in Table 9 below.
TABLE-US-00009 TABLE 9 WATER POLYAMINO- SOLUBLE POLY- FORM. ORGANIC
CARBOXYLIC EX. # SOLVENT TRIAZOLE ACID AMIDINE OXIDIZER H.sub.2O
FE-9 PGME (20 g) BTA (0.2 g) EDTA (0.818 g) formamidine ammonium
58.746 g (0.236 g) persulfate (20 g) FE-10 TGA (15 g)
5-amino-triazole CDTA (0.1 g) acetamadine peracetic acid 69.3 g
(0.5 g) (0.1 g) (15 g) FE-11 diethylene 4-n- DAPTA (0.2 g) methyl
ammonium 59.1 g glycol (15 g) butylbenzotriazole acetamidine
perchlorate (0.3 g) (0.4 g) (25 g) FE-12 2,3- benzotriazole-5- PDTA
(0.3 g) ethyl ammonium 53.7 g butanediol carboxylic acid
acetamidine periodate (15 g) (30 g) (0.7 g) (0.3 g) FE-13 Ethylene
naphthotriazole EDDA (0.5 g) diminazen Methane 43.7 g glycol (0.1
g) (0.7 g) persulfonic acid monobenzyl (30 g) ether (25 g) FE-14
cyclo- 5-phenyl- TTHA (0.60 g) benzamidine urea/hydrogen 78.065 g
hexanone benzotriazole (0.535 g) peroxide (10 g) (10 g) (0.8 g)
FE-15 Propargyl 5- EDTA (0.75 g) formamidine p-toluene 63.25 g
alcohol (20 g) hydroxybenzotriazole (0.6 g) persulfonic acid (0.4
g) (15 g) FE-16 2-butenyl 3-amino-5-mercapto- CDTA (0.1 g)
acetamadine Perphosphoric 69.75 g alcohol (10 g) 1,2,4-triazole
(0.1 g) acid (20 g) (0.05 g) FE-17 methanol (20 g) BTA (0.4 g)
DAPTA (0.25 g) diminazen Tetramethyl- 68.95 g (0.4 g) ammonium
perchlorate (10 g) FE-18 Pinacol 5-nitrobenzotriazole EDDA (0.65 g)
methyl di-tert-butyl 62.075 (22 g) (0.075 g) acetamidine peroxide
(15 g) (0.2 g) PGME = propylene glycol monomethyl ether CDTA =
trans-1,2-diaminocyclohexane tetraacetic acid TTHA =
triethylenetetraminehexaacetic acid BTA = benzotriazole DAPTA =
diaminopropanol tetraacetic acid PDTA = propylenediaminetetraacetic
acid EDDA = ethylenediamine dipropionic acid
* * * * *