U.S. patent application number 15/028491 was filed with the patent office on 2016-08-18 for method and composition for selectively removing metal hardmask and other residues from semiconductor device substrates comprising low-k dielectric material and copper.
The applicant listed for this patent is EKC TECHNOLOGY, INC.. Invention is credited to Hua Cui.
Application Number | 20160240368 15/028491 |
Document ID | / |
Family ID | 52810036 |
Filed Date | 2016-08-18 |
United States Patent
Application |
20160240368 |
Kind Code |
A1 |
Cui; Hua |
August 18, 2016 |
METHOD AND COMPOSITION FOR SELECTIVELY REMOVING METAL HARDMASK AND
OTHER RESIDUES FROM SEMICONDUCTOR DEVICE SUBSTRATES COMPRISING
LOW-K DIELECTRIC MATERIAL AND COPPER
Abstract
An aqueous removal composition having a pH in the range of from
2 to 14 and method for selectively removing an etching mask
consisting essentially of TiN, TaN, TiNxOy, TiW, W, or alloy of Ti
or W relative to low-k materials from a semiconductor substrate
comprising said low-k materials having a TiN, TaN, TiNxOy, TiW, W,
or alloy of Ti or W etching mask thereon wherein the removal
composition comprises at least one oxidizing agent and a
carboxylate compound.
Inventors: |
Cui; Hua; (Castro Valley,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EKC TECHNOLOGY, INC. |
Hayward |
CA |
US |
|
|
Family ID: |
52810036 |
Appl. No.: |
15/028491 |
Filed: |
November 14, 2014 |
PCT Filed: |
November 14, 2014 |
PCT NO: |
PCT/US13/74356 |
371 Date: |
April 11, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61889968 |
Oct 11, 2013 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23F 1/38 20130101; C11D
3/2082 20130101; C23F 1/28 20130101; G03F 7/423 20130101; H01L
21/02057 20130101; C11D 7/3218 20130101; B08B 3/10 20130101; C11D
3/3942 20130101; C11D 7/04 20130101; H01L 21/31144 20130101; G03F
7/426 20130101; C11D 7/3245 20130101; C11D 7/265 20130101; H01L
21/76814 20130101; H01L 21/76807 20130101; C23F 1/18 20130101; C23F
1/26 20130101; C11D 7/3209 20130101; B08B 3/08 20130101; H01L
21/02063 20130101; H01L 21/32134 20130101; C11D 11/0047 20130101;
C23F 1/34 20130101; G03F 7/425 20130101; C11D 3/3947 20130101; H01L
21/31111 20130101; C11D 7/3281 20130101; C23F 1/40 20130101 |
International
Class: |
H01L 21/02 20060101
H01L021/02; C11D 11/00 20060101 C11D011/00; C11D 7/32 20060101
C11D007/32; C11D 7/26 20060101 C11D007/26; B08B 3/08 20060101
B08B003/08; C11D 7/04 20060101 C11D007/04 |
Claims
1. A removal composition having a pH in the range of from 2 to 14
for selectively removing an etching mask consisting essentially of
TiN, TaN, TiNxOy, TiW, W, and alloys of Ti and W relative to low-k
dielectric material from a semiconductor device substrate which
comprises said low-k dielectric material having a TiN, TaN, TiNxOy,
TiW, W, or alloy of Ti or W etching mask thereon, wherein said
removal composition comprises: (a) from 0.1 wt % to 90 wt % of an
oxidizing agent; (b) from 0.0001 wt % to 50 wt % of an ammonium
carboxylate; and (c) the balance up to 100 wt % of said removal
composition comprising deionized water.
2. The removal composition of claim 1 further comprising an organic
cosolvent that is miscible with water.
3. The removal composition of claim 1 or claim 2 wherein (a) said
oxidizing agent is selected from the group consisting essentially
of hydrogen peroxide (H.sub.2O.sub.2), n-methylmorpholine oxide
(NMMO or NMO), benzoyl peroxide, tetrabutylammonium
peroxymonosulfate, ozone, ferric chloride, permanganate
peroxoborate, perchlorate, persulfate, ammonium peroxydisulfate,
per acetic acid, urea hydroperoxide, nitric acid (HNO.sub.3),
ammonium chlorite (NH.sub.4CIO.sub.2), ammonium chlorate
(NH.sub.4CIO.sub.3), ammonium iodate (NH.sub.4IO.sub.3), ammonium
perborate (NH.sub.4BO.sub.3), ammonium perchlorate
(NH.sub.4CIO.sub.4), ammonium periodate (NH.sub.4IO.sub.3),
ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8),
tetramethylammonium chlorite ((N(CH.sub.3).sub.4)CIO.sub.2),
tetramethylammionium chlorate ((N(CH.sub.3).sub.4)CIO.sub.3),
tetramethylammonium iodate ((N(CH.sub.3).sub.4)IO.sub.3),
tetramethylammonium perborate ((N(CH.sub.3).sub.4)BO.sub.3),
tetramethylammonium perchlorate ((N(CH.sub.3).sub.4)CIO.sub.4),
tetramethylammonium periodate ((N(CH.sub.3).sub.4)IO.sub.4),
tetramethylammonium persulfate ((N(CH.sub.3).sub.4)S.sub.2O.sub.8),
((CO(NH.sub.2).sub.2)H.sub.2O.sub.2), peracetic acid
(CH.sub.3(CO)OOH), and mixtures thereof; and (b) said ammonium
carboxylate is selected from the group comprising ammonium oxalate,
ammonium lactate, ammonium tartrate, ammonium citrate tribasic,
ammonium acetate, ammonium carbamate, ammonium carbonate, ammonium
benzoate, tetraammonium EDTA, ethylenediaminetetraacetic acid
diammonium salt, ammonium succinate, ammonium formate, ammonium
1-H-pyrazole-3-carboxylate, and mixtures thereof.
4. The removal composition of claim 3 wherein said oxidizing agent
is hydrogen peroxide.
5. The removal composition of claim 1 further comprising from 0.001
wt % to 20 wt % of an amino acid, an aminopolycarboxylic acid, a
carboxylic acid, a polycarboxylic acid, or a mixture thereof
selected from the group consisting essentially of
1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid;
ethylenediaminetetraacetic acid; nitrilotriacetic acid; diethylene
triamine pentaacetic acid;
1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; ethylene
glycol tetraacetic acid (EGTA);
1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid;
N-{2-[bis(carboxymethyl)amino]ethyl}-N-(2-hydroxyethyl)glycine
(HEDTA); and ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)
(EDDHA).
6. The removal composition of claim 1 further comprising from
0.0001 wt % up to 50 wt % of a metal corrosion inhibitor.
7. The removal composition of claim 1 wherein the pH is in the
range of from 3 to 13 and said oxidizing agent is hydrogen
peroxide.
8. The removal composition of claim 7 wherein the pH is in the
range of from 7 to 12.
9. A method for selectively removing an etching mask consisting
essentially of TiN, TaN, TiNxOy, TiW, W, or an alloy of Ti or W
relative to low-k materials from a semiconductor substrate
comprising said low-k materials having an etching mask consisting
essentially of TiN, TaN, TiNxOy, TiW, W, or an alloy of Ti or W
thereon wherein the method comprises contacting the substrate with
a removal composition comprising: (a) from 0.1 wt % to 90 wt % at
least one oxidizing agent, (b) from 0.0001 wt % to 50 wt % of an
ammonium carboxylate; and (c) the balance up to 100 wt % of said
removal composition comprising deionized water at a temperature in
the range of from room temperature up to 80.degree. C. and at a pH
in the range of from 3 to 13 for a time wherein said removal
composition selectively removes said TiN, TaN, TiNxOy, TiW, W, or
alloy of Ti or W etching mask relative to said low-k materials, and
the achievable etch rate of the composition remains substantially
constant over an extended period of time.
10. The method of claim 9 wherein: (a) said oxidizing agent is
selected from the group consisting essentially of hydrogen peroxide
(H.sub.2O.sub.2), n-methylmorpholine oxide (NMMO or NMO), benzoyl
peroxide, tetrabutylammonium peroxymonosulfate, ozone, ferric
chloride, permanganate peroxoborate, perchlorate, persulfate,
ammonium peroxydisulfate, per acetic acid, urea hydroperoxide,
nitric acid (HNO.sub.3), ammonium chlorite (NH.sub.4CIO.sub.2),
ammonium chlorate (NH.sub.4CIO.sub.3), ammonium iodate
(NH.sub.4IO.sub.3), ammonium perborate (NH.sub.4BO.sub.3), ammonium
perchlorate (NH.sub.4CIO.sub.4), ammonium periodate
(NH.sub.4IO.sub.3), ammonium persulfate
((NH.sub.4).sub.2S.sub.2O.sub.8), tetramethylammonium chlorite
((N(CH.sub.3).sub.4)CIO.sub.2), tetramethylammionium chlorate
((N(CH.sub.3).sub.4)CIO.sub.3), tetramethylammonium iodate
((N(CH.sub.3).sub.4)IO.sub.3), tetramethylammonium perborate
((N(CH.sub.3).sub.4)BO.sub.3), tetramethylammonium perchlorate
((N(CH.sub.3).sub.4)CIO.sub.4), tetramethylammonium periodate
((N(CH.sub.3).sub.4)IO.sub.4), tetramethylammonium persulfate
((N(CH.sub.3).sub.4)S.sub.2O.sub.8),
((CO(NH.sub.2).sub.2)H.sub.2O.sub.2), peracetic acid
(CH.sub.3(CO)OOH), and mixtures thereof; and (b) said ammonium
carboxylate is selected from the group comprising ammonium oxalate,
ammonium lactate, ammonium tartrate, ammonium citrate tribasic,
ammonium acetate, ammonium carbamate, ammonium carbonate, ammonium
benzoate, tetraammonium EDTA, ethylenediaminetetraacetic acid
diammonium salt, ammonium succinate, ammonium formate, ammonium
1-H-pyrazole-3-carboxylate, and mixtures thereof.
11. The method of claim 10 wherein said removal composition further
comprises from 0.0001 wt % up to 20 wt % of a copper corrosion
inhibitor.
12. The method of claim 10 wherein said removal composition further
comprises from 0.001 wt % to 20 wt % of an amino acid, an
aminopolycarboxylic acid, a carboxylic acid, a polycarboxylic acid,
or a mixture thereof selected from the group consisting essentially
of 1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid;
ethylenediaminetetraacetic acid; nitrilotriacetic acid; diethylene
triamine pentaacetic acid;
1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; ethylene
glycol tetraacetic acid (EGTA);
1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid;
N-{2-[bis(carboxymethyl)amino]ethyl}-N-(2-hydroxyethyl)glycine
(HEDTA); and ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)
(EDDHA) whereby the achievable removal rate for the etching mask
remains substantially constant over an extended period of time up
to at least thirty five hours.
13. A method for selectively removing an etching mask consisting
essentially of TiN, TaN, TiNxOy, TiW, W, or an alloy of Ti or W
relative to low-k materials from a semiconductor substrate
comprising said low-k materials having an etching mask consisting
essentially of TiN, TaN, TiNxOy, TiW, W, or an alloy of Ti or W
thereon wherein the method comprises contacting the substrate with
a removal composition comprising: (a) from 0.1 wt % to 90 wt % of
hydrogen peroxide; (b) from 0.0001 wt % to 50 wt % of an ammonium
carboxylate selected from the group comprising ammonium oxalate,
ammonium lactate, ammonium tartrate, ammonium citrate tribasic,
ammonium acetate, ammonium carbamate, ammonium carbonate, ammonium
benzoate, tetraammonium EDTA, ethylenediaminetetraacetic acid
diammonium salt, ammonium succinate, ammonium formate, ammonium
1-H-pyrazole-3-carboxylate, and mixtures thereof; (c) from 0.001 wt
% to 20 wt % of an amino acid, an aminopolycarboxylic acid, a
carboxylic acid, a polycarboxylic acid, or a mixture thereof
selected from the group consisting essentially of
1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid;
ethylenediaminetetraacetic acid; nitrilotriacetic acid; diethylene
triamine pentaacetic acid;
1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; ethylene
glycol tetraacetic acid (EGTA); and
1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; and (d)
the balance up to 100 wt % of said removal composition comprising
deionized water at a temperature in the range of from room
temperature up to 80.degree. C. and at a pH in the range of from 3
to 13 for a time wherein said removal composition selectively
removes said TiN, TaN, TiNxOy, TiW, W, or alloy of Ti or W etching
mask relative to said low-k materials whereby the etching mask is
selectively removed and the achievable removal rate for the etching
mask remains substantially constant over an extended period of
time.
Description
CROSS REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE
STATEMENT
[0001] This application claims the benefit of U.S. provisional
application Ser. No. 61/889,968, filed Oct. 11, 2013, the entire
contents of which are hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The presently disclosed and claimed inventive concept(s)
relates to compositions and methods for selectively removing metal
hardmask and other residues from integrated circuit (IC) device
substrates, and, more particularly, to compositions and methods
useful for selectively removing TiN, TaN, TiNxOy, TiW, and W metal
hardmask, and metal hardmasks comprising alloys of the foregoing,
as well as other residues from such substrates comprising low-k
dielectric materials, TEOS, copper, cobalt and other low-k
dielectric materials, using carboxylate compounds.
[0003] Devices with critical dimensions on the order of 90
nanometers (nm) have involved integration of copper conductors and
low-k dielectrics, and they require alternating material deposition
processes and planarization processes. Plasma dry etching is
commonly used to fabricate vertical sidewall trenches and
anisotropic interconnecting vias in copper (Cu)/low-k dual
damascene fabrication processes. As the technology nodes advance to
45 nm and smaller, the decreasing size of the semiconductor devices
makes achieving critical profile control of vias and trenches more
challenging. Integrated circuit device companies are investigating
the use of a variety of metal hardmasks to improve etch selectivity
to low-k materials and thereby gain better profile control.
[0004] In order to obtain high yield and low resistance, polymer
residues on the sidewalls and the particulate/polymer residues at
the via bottoms that are generated during etching must be removed
prior to the next process step. It would be very beneficial if the
cleaning solution can also effectively etch the metal
CROSS REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE
STATEMENT
[0005] This application claims the benefit of U.S. provisional
application Ser. No. 61/889,968, filed Oct. 11, 2013, the entire
contents of which are hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0006] The presently disclosed and claimed inventive concept(s)
relates to compositions and methods for selectively removing metal
hardmask and other residues from integrated circuit (IC) device
substrates, and, more particularly, to compositions and methods
useful for selectively removing TiN, TaN, TiNxOy, TiW, and W metal
hardmask, and metal hardmasks comprising alloys of the foregoing,
as well as other residues from such substrates comprising low-k
dielectric materials, TEOS, copper, cobalt and other low-k
dielectric materials, using carboxylate compounds.
[0007] Devices with critical dimensions on the order of 90
nanometers (nm) have involved integration of copper conductors and
low-k dielectrics, and they require alternating material deposition
processes and planarization processes. Plasma dry etching is
commonly used to fabricate vertical sidewall trenches and
anisotropic interconnecting vias in copper (Cu)/low-k dual
damascene fabrication processes. As the technology nodes advance to
45 nm and smaller, the decreasing size of the semiconductor devices
makes achieving critical profile control of vias and trenches more
challenging. Integrated circuit device companies are investigating
the use of a variety of metal hardmasks to improve etch selectivity
to low-k materials and thereby gain better profile control.
[0008] In order to obtain high yield and low resistance, polymer
residues on the sidewalls and the particulate/polymer residues at
the via bottoms that are generated during etching must be removed
prior to the next process step. It would be very beneficial if the
cleaning solution can also effectively etch the metal Cu oxide from
the resulting dual damascene structure. Beyond selective cleaning,
it is also highly desirable that the achievable removal rate
(.ANG./min) for the cleaning composition be maintained
substantially constant for an extended period of time.
[0009] With the continuing reduction in device critical dimensions
and corresponding requirements for high production efficiency and
reliable device performance, there is a need for such improved
cleaning compositions.
SUMMARY OF THE INVENTION
[0010] The presently disclosed and claimed inventive concept(s)
relate to an improved semiconductor processing composition, i.e., a
wet cleaning chemistry or removal composition, with one or more
carboxylate compounds which provides highly selective removal of
metal hardmask from a dual damascene structure without damaging
wiring metallurgy and dielectric materials. Semiconductor
substrates of the type fabricated in dual damascene back end
metallization consist of multiple layers or levels of metal
interconnects that are isolated by interlayer dielectrics. The
described composition can remove metal hardmask etch residues,
photoresist, polymeric materials, and copper oxide from via and
trench surfaces without damaging underlying layers that form the
structure. The substrates typically comprise copper, cobalt, a
low-k dielectric material(s), SiON, SiCN, TEOS and metal hard mask
selected from TiN, TaN, TiNxOy, TiW and W, including alloys of Ti
and W. The removal composition comprises from 0.1 wt % to 90 wt %
at least one oxidizing agent, from 0.0001 wt % to 50 wt % of a
carboxylate compound, with the balance up to 100 wt % of the
removal composition comprising water, e.g., deionized water.
[0011] Among the carboxylate compounds found to produce excellent
results according to the inventive concept(s) described herein are
ammonium carboxylates. Examples of ammonium carboxylates are
ammonium oxalate, ammonium lactate, ammonium tartrate, ammonium
citrate tribasic, ammonium acetate, ammonium carbamate, ammonium
carbonate, ammonium benzoate, tetraammonium EDTA,
ethylenediaminetetraacetic acid diammonium salt, ammonium
succinate, ammonium formate, ammonium 1-H-pyrazole-3-carboxylate,
and mixtures thereof. The presence of an ammonium carboxylate
compound in the removal compositions of the invention not only
increased TiN etch rate as shown in the Examples which follow, but
the data support the conclusion that their presence also operates
to stabilize the achievable TiN etch rate over an extended period
of time, e.g., up to at least 35 hrs.
[0012] Although not required for carrying out the invention, at
least one corrosion inhibitor may also be present in the
composition, for example, where the composition is to be deployed
in semiconductor processing at BEOL applications and other
applications where corrosion of Cu or other metal components is a
concern.
[0013] The composition may also include a base, for example,
selected from the group consisting of quaternary ammonium salts,
such as tetramethylammonium hydroxide (TMAH), tetraethylammonium
hydroxide (TEAH) and benzyltrimethylammonium hydroxide (BTAH), and
mixtures thereof. The base can also be selected from a primary,
secondary or tertiary amine, such as, for example, monoethanol
amine (MEA), diglycol amine (DGA), triethanolamine (TEA); and
tetrabutyphosphonium hydroxide (TBPH) and mixtures thereof. In
addition, the composition may include one or more acids, for
example, an inorganic acid, such as sulfuric acid, nitric acid,
phosphoric acid, hydrofluoric acid (HF), or hydrobromic acid, or an
organic acid, such as a carboxylic acid, hydroxy carboxylic acid,
polycarboxylic acid, amino acid, or a mixture of such acids, as
appropriate to adjust the pH of the working composition to a value
of from 2 to 14, but preferably in the range of from 3 to 13. In a
preferred embodiment, for applications involving Cu interconnect
fabrication, the pH of the removal composition is preferably in the
range of from 7 to 12.
[0014] The composition may also include from 0.001 wt % to 20 wt %
of an amino acid, amine polycarboxylic acid (i.e.,
aminopolycarboxylic acid), and/or carboxylic acid, polycarboxylic
acid chelating agent, or a mixture thereof, which, along with the
carboxylate compound, has been observed to stabilize the
composition. The term "stabilize" is used herein to mean that the
achievable etch rate for a hard mask (e.g., a removal rate for TiN
of 148 .ANG./min) remains substantially constant over an extended
period of time, e.g., a time period of from twenty two (22) hours
and up to thirty five (35) hours or longer at the selected
operating temperature, for example, at an operating temperature of
50.degree. C.
[0015] Oxidizing agents suitable for carrying out the inventive
concepts can be selected from the group consisting of hydrogen
peroxide (H.sub.2O.sub.2), benzoyl peroxide, tetrabutylammonium
peroxymonosulfate, ozone, n-methylmorpholine oxide (NMMO, NMO),
ferric chloride, permanganate, peroxoborate, perchlorate,
persulfate, ammonium peroxydisulfate, per acetic acid, urea
hydroperoxide, percarbonate, perborate, and mixtures thereof. Best
results have been observed when the oxidizing agent is hydrogen
peroxide (H.sub.2O.sub.2).
[0016] In another embodiment the invention comprises a method for
selectively removing an etching mask consisting essentially of TiN,
TaN, TiNxOy, TiW or W, including alloys of Ti or W, relative to
underlying low-k, Cu, Co, SiON, SICN, and TEOS materials from a
semiconductor substrate having a TiN, TaN, TiNxOy, TiW or W,
etching mask thereon, including an etching mask comprising alloys
of Ti or W, wherein the method comprises contacting the substrate
with a removal composition comprising:
[0017] (a) from 0.1 wt % to 90 wt % at least one oxidizing
agent;
[0018] (b) from 0.0001 wt % up to 50 wt % of an ammonium
carboxylate selected from the group comprising one or more of
ammonium oxalate, ammonium lactate, ammonium tartrate, ammonium
citrate tribasic, ammonium acetate, ammonium carbamate, ammonium
carbonate, ammonium Benzoate, tetraammonium EDTA,
ethylenediaminetetraacetic acid diammonium salt, ammonium
succinate, ammonium formate, and ammonium
1-H-pyrazole-3-carboxylate; and
[0019] (c) the balance up to 100 wt % of said removal composition
comprising deionized water at a temperature in the range of from
room temperature up to 80.degree. C. and at a pH in the range of
from 2 to 14, wherein the removal composition selectively removes
said TiN, TaN, TiNxOy, TiW or W, including alloys of Ti and/or W,
etching mask relative to said low-k, Cu, Co, TEOS and other
dielectric materials.
[0020] In another embodiment the invention comprises a method for
selectively removing an etching mask consisting essentially of TiN,
TaN, TiNxOy, TiW or W, including alloys of Ti and/or W, relative to
underlying low-k, Cu, Co, SiON, SICN, and TEOS materials from a
semiconductor substrate having a TiN, TaN, TiNxOy, TiW or W,
etching mask thereon, including an etching mask comprising alloys
of Ti and/or W, wherein the method comprises contacting the
substrate with a removal composition comprising:
[0021] (a) from 0.1 wt % to 90 wt % at least one oxidizing
agent;
[0022] (b) from 0.0001 wt % up to 50 wt % of an ammonium
carboxylate selected from the group comprising one or more of
ammonium oxalate, ammonium lactate, ammonium tartrate, ammonium
citrate tribasic, ammonium acetate, ammonium carbamate, ammonium
carbonate, ammonium Benzoate, tetraammonium EDTA,
ethylenediaminetetraacetic acid diammonium salt, ammonium
succinate, ammonium formate, and ammonium
1-H-pyrazole-3-carboxylate;
[0023] (c) from 0.001 wt % to 20 wt % of an amino acid, amine
polycarboxylic acid (i.e., aminopolycarboxylic acid), and/or
carboxylic acid, polycarboxylic acid chelating agent, or a mixture
thereof; and
[0024] (d) the balance up to 100 wt % of said removal composition
comprising deionized water at a temperature in the range of from
room temperature up to 80.degree. C. and at a pH in the range of
from 2 to 14, wherein the removal composition selectively removes
said TiN, TaN, TiNxOy, TiW and W, including alloys of Ti and W,
etching mask relative to said low-k, Cu, Co, TEOS and other
dielectric materials, and the rate at which said etching mask is
removed remains constant over an extended period of time which can
be as long as thirty five (35) hours or longer.
[0025] In another embodiment, the described and claimed inventive
concept(s) embraces an improvement to a composition and method for
selectively removing an etching mask consisting essentially of TiN,
TaN, TiNxOy, TiW or W, including alloys of Ti or W, relative to
underlying low-k, Cu, Co, SiON, SICN, and TEOS materials from a
semiconductor substrate having a TiN, TaN, TiNxOy, TiW or W,
etching mask thereon, including an etching mask comprising alloys
of Ti or W, wherein the improvement comprises incorporating into
said removal composition from 0.0001 wt % to 50 wt % of an ammonium
carboxylate selected from the group comprising ammonium oxalate,
ammonium lactate, ammonium tartrate. ammonium citrate tribasic,
ammonium acetate, ammonium carbamate, ammonium carbonate, ammonium
benzoate, tetraammonium EDTA, ethylenediaminetetraacetic acid
diammonium salt, ammonium succinate, ammonium formate, ammonium
1-H-pyrazole-3-carboxylate whereby said removal composition
selectively removes said TiN, TaN, TiNxOy, TiW, W, or alloy of Ti
or W etching mask relative to said low-k materials.
[0026] The amount and type of undesirable residue to be removed in
any given processing step will influence the selection of operating
pH for the composition.
[0027] The compositions and method according to the inventive
concepts described herein are uniquely capable of selectively
etching TiN, TaN, TiNxOy, TiW and W, including alloys of Ti and W,
are compatible with Cu, Co, low-k and TEOS dielectric materials,
and can also simultaneously remove copper oxides, polymeric
materials and etch residues from the substrate, i.e., the dual
damascene structure, being treated.
[0028] A composition formulated according to the invention and
exhibiting an inherently high etch rate for TiN, TaN, TiNxOy, TiW
and W, including alloys of Ti and W, enables processing at
relatively low temperature, e.g., temperatures less than 65.degree.
C. A relatively low temperature process exhibits a reduced oxidizer
decomposition rate, which, in turn, extends the useful composition
bath life and pot life. Additionally, compositions according to the
invention which exhibit high and selective etch rates for TiN, TaN,
TiNxOy, TiW and W, including alloys of Ti and W, are desirable
because they can reduce device processing time and thereby increase
throughput. Typically, high etch rates for TiN, TaN, TiNxOy, TiW
and W, including alloys of Ti and W, have been achieved by
increasing process temperatures. However, for single wafer process
applications, the highest processing temperature is around
75.degree. C., which, in turn, can limit the upper end of etch
rates for TiN, and thereby limit the ability for one to completely
remove TiN metal hardmask from a dual damascene structure.
Compositions according to the invention can effectively deliver
high etch rates for TiN, TaN, TiNxOy, TiW and W, including alloys
of Ti and W, with single wafer tool applications at a temperature
range of from 20.degree. C. to 60.degree. C., and the TiN, TaN,
TiNxOy, TiW and W, including alloys of Ti and W, metal hardmask can
be fully removed with single wafer application process equipment if
so desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIGS. 1A and 1B are cross-sectional SEM images of
semiconductor wafer segments which show trenches and vias,
respectively, during dual damascene device fabrication, but prior
to contact with the removal composition of the invention.
[0030] FIGS. 2A and 2B are cross-sectional SEM images of
semiconductor wafer segments of the type shown in FIGS. 1A and 1B
after contact with removal composition 1 from Table 1 at 50.degree.
C. for 90 sec.
[0031] FIGS. 3A and 3B are cross-sectional SEM images of
semiconductor wafer segments of the type shown in FIGS. 1A and 1B
after contact with removal composition 2 from Table 1 at 50.degree.
C. for 90 sec.
[0032] FIGS. 4A and 4B are cross-sectional SEM images of
semiconductor wafer segments of the type shown in FIGS. 1A and 1B
after contact with removal composition 3 from Table 1 at 53.degree.
C. for 90 sec.
DETAILED DESCRIPTION OF THE INVENTION
[0033] It is recognized that various components of the compositions
of this invention may interact, and, therefore, any composition is
expressed as the amount of various components which, when added
together, form the composition. Unless specifically stated
otherwise, any composition given in percent is percent by weight
(wt %) of that component that has been added to the composition.
When the composition is described as being substantially free of a
particular component, generally there are numeric ranges provided
to guide one of ordinary skill in the art to what is meant by
"substantially free," but in all cases "substantially free"
encompasses the preferred embodiment where the composition is
totally free of that particular component.
[0034] As noted briefly above, the dual damascene process is used
to form metal interconnects in the backend metallization, which are
then used to electrically interconnect various electrical
components in a semiconductor substrate into functional circuits. A
discussion of backend metallization, which comprises fabrication of
multiple levels, or layers, of metal interconnects isolated by an
interlayer dielectric layer(s) and/or barrier layer(s) can be
found, for example, in U.S. Pat. No. 8,080,475, the teachings of
which are incorporated herein in their entirety by reference. The
integration of new materials, such as ultra low-k dielectrics, into
microelectronic devices places new demands on cleaning performance.
Concurrently, shinking device dimensions reduces the tolerances for
changes in critical dimensions for vias and trenches.
[0035] According to a first embodiment, the present invention is a
semiconductor processing composition comprising water, at least one
oxidizing agent, optionally at least one base or acid, depending on
the desired pH for the working composition, and from 0.0001 wt % up
to 50 wt % of an ammonium carboxylate. By way of example, and not
by way of limitation, the ammonium carboxylate can be selected from
the group comprising ammonium oxalate, ammonium lactate, ammonium
tartrate, ammonium citrate tribasic, ammonium acetate, ammonium
carbamate, ammonium carbonate, ammonium benzoate, tetraammonium
EDTA, ethylenediaminetetraacetic acid diammonium salt, ammonium
succinate, ammonium formate, ammonium 1-H-pyrazole-3-carboxylate
and mixtures thereof.
[0036] In a preferred embodiment, the concentration of ammonium
carboxylate is from 0.001 wt % up to 50 wt %. Although not required
for carrying out the invention, at least one corrosion inhibitor
may also be present in the composition where the composition is to
be deployed in BEOL semiconductor processing applications and other
applications where corrosion of metal components, e.g., Cu and
Cu-alloy components, is a concern. In one embodiment, the
formulations preferably have a pH of from 3 to 13. For BEOL Cu
interconnect fabrication it is preferred to have a pH in the range
of from 7 to 12.
[0037] The compositions of the invention are effective in
selectively removing an etching mask consisting essentially of TiN,
TaN, TiNxOy, TiW or W, including alloys of Ti and/or W, relative to
low-k materials from a semiconductor substrate comprising said
low-k dielectric material and having a TiN, TaN, TiNxOy, TiW and W,
including alloys of Ti and/or W, etching mask thereon. In addition,
the composition is also functional in simultaneously removing
photoresist, polymeric materials, etching residues and copper oxide
from the substrate.
[0038] The compositions of the invention may also include from
0.001 wt % to 20 wt % of an amino acid, amine polycarboxylic acid
(i.e., aminopolycarboxylic acid), and/or carboxylic acid,
polycarboxylic acid chelating agent, or a mixture thereof,
preferably from 0.001 wt % to 10 wt %, and more preferably from
0.001 wt % to 5 wt %. The presence of an amino acid, amine
polycarboxylic acid (i.e., aminopolycarboxylic acid), and/or
carboxylic acid, polycarboxylic acid chelating agent, or a mixture
thereof, according to the described and claimed inventive concepts
has been observed to stabilize the composition. The term
"stabilize" is used herein to mean that the achievable etch rate
for a hard mask (i.e., the removal rate) remains substantially
constant over an extended period of time at the selected operating
temperature. Examples of such chelating agents include, but are not
limited to, 1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid;
ethylenediaminetetraacetic acid; nitrilotriacetic acid; diethylene
triamine pentaacetic acid;
1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; ethylene
glycol tetraacetic acid (EGTA);
1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid;
N-{2-[bis(carboxymethyl)amino]ethyl}-N-(2-hydroxyethyl)glycine
(HEDTA); and ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)
(EDDHA).
[0039] The compositions and method according to the inventive
concepts described herein are particularly applicable for
processing single wafers in single wafer equipment. When a high TiN
etch rate is required, a common approach is to process wafers a
high process temperatures. However, higher temperatures are known
to contribute to degradation of the oxidizing agent which shortens
bath life and pot life. It has been observed according to the
inventive concepts described herein that satisfactory results can
be achieved at substantially lower temperatures in the range of
from 20.degree. C. to 60.degree. C. to generate a pullback scheme
or to completely remove the metal hardmask when the hardmask
comprises TiN.
Cosolvent
[0040] In some embodiments of this invention, the composition can
contain one or more cosolvents that are miscible with water. These
cosolvents enhance residue removal. Suitable cosolvents include,
but are not limited to, sulfolane, N-methylpyrrolidone, and
dimethylsulfoxide.
Oxidizing Agent
[0041] Oxidizing agents useful according to the inventive
concept(s) are selected from any substance which has the capability
to chemically react with the metal hardmask and effect its removal.
Such oxidizing agents include, but are not limited to, the group
consisting essentially of hydrogen peroxide (H.sub.2O.sub.2),
n-methylmorpholine oxide (NMMO or NMO), benzoyl peroxide,
tetrabutylammonium peroxymonosulfate, ozone, ferric chloride,
permanganate peroxoborate, perchlorate, persulfate, ammonium
peroxydisulfate, per acetic acid, urea hydroperoxide, nitric acid
(HNO.sub.3), ammonium chlorite (NH.sub.4CIO.sub.2), ammonium
chlorate (NH.sub.4CIO.sub.3), ammonium iodate (NH.sub.4IO.sub.3),
ammonium perborate (NH.sub.4BO.sub.3), ammonium perchlorate
(NH.sub.4CIO.sub.4), ammonium periodate (NH.sub.4IO.sub.3),
ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8),
tetramethylammonium chlorite ((N(CH.sub.3).sub.4)CIO.sub.2),
tetramethylammionium chlorate ((N(CH.sub.3).sub.4)CIO.sub.3),
tetramethylammonium iodate ((N(CH.sub.3).sub.4)IO.sub.3),
tetramethylammonium perborate ((N(CH.sub.3).sub.4)BO.sub.3),
tetramethylammonium perchlorate ((N(CH.sub.3).sub.4)CIO.sub.4),
tetramethylammonium periodate ((N(CH.sub.3).sub.4)IO.sub.4),
tetramethylammonium persulfate ((N(CH.sub.3).sub.4)S.sub.2O.sub.8),
((CO(NH.sub.2).sub.2)H.sub.2O.sub.2), peracetic acid
(CH.sub.3(CO)OOH), and mixtures thereof. Among the foregoing,
H.sub.2O.sub.2 is a most preferred oxidizing agent being free of
metals and providing ease of handling and lower relative cost.
[0042] The oxidizing agent or mixture thereof may be present in the
composition at from about 0.1 wt % to about 90 wt %, preferably at
from about 5 wt % to 90 wt %, and, for best results, preferably 10
wt % to 90 wt %.
pH Adjustment
[0043] The composition may also include a base or an acid, as
appropriate, to adjust the pH of the working composition. The base
can, for example, be selected from quaternary ammonium salts, such
as tetramethylammonium hydroxide (TMAH), tetraethylammonium
hydroxide (TEAH), benzyltrimethylammonium hydroxide (BTAH) and
mixtures thereof. The base can also be selected from primary,
secondary and tertiary amines, such as, for example, monoethanol
amine (MEA), diglycol amine (DGA), triethanolamine (TEA),
tetrabutyphosphonium hydroxide (TBPH), and mixtures thereof. In
some embodiments, the base can be a combination of quaternary
ammonium salts and amines. Suitable acids include, for example,
inorganic acids, such as sulfuric acid, nitric acid, phosphoric
acid, hydrofluoric acid (HF), or hydrobromic acid, or an organic
acid, such as a carboxylic acid, an amino acid, a hydroxy
carboxylic acid, a polycarboxylic acid, or a mixture of such acids.
The pH of the working composition should be maintained at a value
of from 2 to 14, but preferably in the range of from 3 to 12. As
noted above, when used in BEOL Cu interconnect fabrication
applications, the preferred pH of the working composition is in the
range of from 7 to 12 when hydrogen peroxide is used as oxidizer in
order to achieve high TiN etch rates.
Metal Corrosion Inhibitor
[0044] A Cu or Co corrosion inhibitor, or a mixture thereof, is an
optional component in the composition of this invention. A Cu or Co
corrosion inhibitor(s) will usually be present in the inventive
composition and associated process when used for BEOL applications,
where the presence of a corrosion inhibitor is needed to protect
metal surfaces from being etched or otherwise degraded. For other
applications, including FEOL applications, of the inventive
composition and associated method, a corrosion inhibitor(s) is not
generally needed, i.e., Cu or Co, is not exposed to the cleaning
chemistry, Cu or Co is absent from the wafer substrate, or slight
etching/degradation of copper or cobalt surfaces is not usually a
concern.
[0045] The metal (Cu or Co) corrosion inhibitor is an organic
compound, such as an azole, thiol, and/or indole preferably
selected from the group consisting of a heterocyclic compound
containing at least one nitrogen atom, such as, for example, a
pyrrole and derivatives thereof, pyrazole and derivatives thereof,
imidazole and derivatives thereof, triazole and derivatives
thereof, indazole and derivatives thereof, and thiol-triazole and
derivatives thereof, benzotriazole (BTA), tolyltriazole,
5-phenyl-benzotriazole, 5-nitro-benzotriazole,
3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole,
hydroxybenzotriazole, 2-(5-amino-pentyl)-benzotriazole,
1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole,
3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole,
3-isopropyl-1,2,4-triazole, 5-phenylthiol-benzotriazole,
halo-benzotriazoles (halo=F, Cl, Br or I), naphthotriazole,
2-mercaptobenzimidazole (MBI), 2-mercaptobenzothiazole,
4-methyl-2-phenylimidazole, 2-mercaptothiazoline, 5-aminotetrazole,
5-aminotetrazole monohydrate, 5-amino-1,3,4-thiadiazole-2-thiol,
2,4-diamino-6-methyl-1,3,5-triazine, thiazole, triazine,
methyltetrazole, 1,3-dimethyl-2-imidazolidinone,
1,5-pentamethylenetetrazole, 1-phenyl-5-mercaptotetrazole,
diaminomethyltriazine, imidazoline thione, mercaptobenzimidazole,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, and mixtures
thereof. Among the foregoing, BTA, pyrazole, or a mixture of BTA
and pyrazole, or a mixture of BTA and tolyltriazole (available
commercially from Wincom, Inc. under the name "Wintrol A-90"), are
preferred Cu corrosion inhibitors for better cleaning
performance.
[0046] The Cu or Co corrosion inhibitor or mixture thereof may be
present in the composition at from about 0.0001 wt % to about 50 wt
%, and preferably, for best results, at from about 0.0001 wt % to
about 20 wt %.
[0047] Other suitable Cu or Co corrosion inhibitors include, but
are not limited to aromatic hydrazides and Schiff base
compounds.
Carboxylates
[0048] The described and claimed inventive concept(s) reside in the
discovery that complete removal of metal hard mask from
semiconductor devices wherein said metal hardmask is in overlapping
relationship with a low-k dielectric material can be accomplished
by incorporating into the removal composition an effective amount
of from 0.0001 wt % up to 50 wt % of a carboxylate compound, but
particularly an ammonium carboxylate. In a preferred embodiment,
the concentration of ammonium carboxylate is from 0.001 wt % up to
10 wt %.
[0049] As shown in the Examples which follow, the presence of an
ammonium carboxylate compound in the removal compositions of the
invention not only increased TiN etch rate, but the data support
the conclusion that their presence also operates to stabilize the
achievable TiN etch rate over an extended period of time, e.g., up
to at least 35 hrs.
[0050] The term "carboxylate" is used herein to mean the general
formula M(RCOO).sub.n, where M is a metal and n is 1, 2, . . . is
the number of carboxylate esters within the compound having the
general formula RCOOR', wherein R and R' are organic groups with
the proviso that R'.noteq.H. When chemistries of the type described
herein are used in electronic device fabrication, such as
fabricating IC devices, it is preferable not to have any metal
impurities in the chemical composition. In such cases, M is
replaced with NH4.sup.+. Ammonium carboxylates are preferred
chemicals for use in the removal formulation(s), and they can be
added directly to the composition, or they can be generated as
byproducts or intermediates by chemical reaction during
processing.
Examples
[0051] Removal compositions according to the invention are now
explained in detail by reference to the inventive concepts and
examples which follow, but the present invention is not limited by
these examples and the results shown for each test. Compositions of
the invention may be embodied in a wide variety of specific
formulations, as hereinafter more fully described. In all such
compositions, wherein specific components of the composition are
discussed in reference to weight percentage ranges including a zero
lower limit, it will be understood that such components may be
present or absent in various specific embodiments of the
composition, and that in instances where such components are
present, they may be present at concentrations as low as 0.0001 wt
%, based on the total weight of the composition in which such
components are employed.
[0052] In the examples which follow, 100 g. samples of removal
compositions were prepared according to the inventive concept(s)
described herein. Each sample composition comprised each of the
components listed in the various tables which follow at the weights
shown in the corresponding formulation row. For example, a 100 g.
quantity of sample composition designated "1" shown in Table 1
contained 2 g. of 10% aqueous ammonium tartrate, 7.21 g. of 10%
aqueous DGA, 12.43 g. of 1.5% aqueous BTA, 60 g. H.sub.2O.sub.2
(30% aqueous), and 18.36 g. deionized water (DIW).
[0053] The removal compositions can be formulated at the point of
use, or they can be conveniently formulated beforehand without an
oxidizer and then taken to the point of use where the oxidizer is
added. There is also no particular sequence for mixing or blending
the various ingredients.
TiN, Cu, Co, W and TEOS Etch Rate
[0054] Etch rate evaluations were carried out after 1 and 2 minutes
of chemical treatment at 60.degree. C. and 50.degree. C.,
respectively, for TiN and 10 minutes for Cu, Co, W, and TEOS. TiN,
Cu, Co, and W thicknesses were measured using a Four Dimensions
Four Point Probe Meter 333A, whereby the resistivity of the film
was correlated to the thickness of the film remaining after contact
with the composition of the invention. The TEOS thickness was
measured with Auto SE Spectroscopic Ellipsometer by HORIBA JOBIN
YVON. The etch rate was calculated as the thickness change (before
and after chemical treatment) divided by the chemical treatment
time. Chemical solution pH was measured with a Beckman 260
pH/Temp/mV meter. The H.sub.2O.sub.2 used in the experiments was
sourced from J. T. Baker. Residue removal efficiency and TiN
hardmask etch were evaluated from SEM results (Hitachi S-5500).
[0055] The compositions shown in Table 1 were prepared using
deionized water as the solvent, BTA or a mixture of BTA and
pyrazole as Cu corrosion inhibitor, H.sub.2O.sub.2 as the oxidizing
agent, and diglycolamine (DGA) or benzyltrimethylammonium hydroxide
(BTAH) as the base to adjust pH. TiN and Cu etch rate evaluations
were carried out as described above at a temperature of 50.degree.
C. and a pH of about 8.
TABLE-US-00001 TABLE 1 Ammonium Benzyltrimethylammonium Tartrate
DGA Hydroxide BTA H.sub.2O.sub.2 Test (10%) (10%) (40%) Pyrazole
(1.5%) (30%) DIW pH TiN (.ANG./min) Cu (.ANG./min) 1 2 7.210 0 0
12.43 60 18.36 8.4 178 (50.degree. C.) 1.3 (50.degree. C.) 2 3
3.010 0 0.5 10 70 13.49 7.6 209 (50.degree. C.) 1.9 (50.degree. C.)
3 3.5 0.000 2.564 0.2 11.25 60 22.49 8.4 340 (53.degree. C.) 2.5
(53.degree. C.)
[0056] Compositions 1, 2 and 3 demonstrated a removal rate for TiN
in the range of from 178 .ANG./min up to 340 .ANG./min at a
relatively low temperature in the range of from 50.degree. C. to
53.degree. C. A copper etch rate of 2.5 .ANG./min or less is
considered good for commercial wafer processing.
[0057] Referring now to the Figs., FIGS. 1A and 1B are SEM images
of semiconductor wafer segments which show trenches and vias,
respectively, as received following a dual damascene fabrication
step, but before treatment with a removal composition. FIGS. 2A and
2B are views of the wafer segments, similar to the wafer segments
shown in FIGS. 1A and 1B, after contact with removal composition 1
for 90 sec. at a temperature of 50.degree. C. Residue was removed,
but some TiN hardmask remained as noted in FIG. 2A. FIGS. 3A and 3B
are views of wafer segments, similar to the wafer segments shown in
FIGS. 1A and 1B, after contact with removal composition 2 for 90
sec. at a temperature of 50.degree. C. wherein TiN hardmask and
residue have been completely removed. FIGS. 4a and 4B are views of
wafer segments, similar to the wafer segments shown in FIGS. 1A and
1B, after contact with removal composition 3 for 90 sec. at a
temperature of 53.degree. C. TiN hardmask and residue have been
completely removed.
[0058] The compositions shown in Table 2 were prepared using
deionized water as the solvent, BTA as Cu corrosion inhibitor,
H.sub.2O.sub.2 as the oxidizing agent, and tetramethylammonium
hydroxide (TMAH) as the base to adjust pH. TiN and Cu etch rate
evaluations were carried out as described above at a temperature of
60.degree. C. and a pH of about 7.8.
[0059] Each of the removal compositions, which contain,
respectively, the compounds ammonium lactate, ammonium tartrate,
ammonium carbonate, and ammonium citrate tribasic at the amounts
indicated, demonstrated a higher TiN etch rate compared with the
corresponding control, composition 4, that did not contain an
ammonium carboxylate.
TABLE-US-00002 TABLE 2 Ammonium Ammonium Ammonium Ammonium Citrate
Lactate Tartrate Carbonate Tribasic BTA TMAH H.sub.2O.sub.2 TiN
(.ANG./min) Cu (.ANG./min) Test (10%) (10%) (10%) (10%) (1.5%)
(25%) DIW (30%) pH at 60.degree. C. at 60.degree. C. 4 0 0 0 0 12
0.816 27.18 60 7.8 215 0.98 5 1.632 0 0 0 12 0.409 25.96 60 7.8 404
1.61 6 0 2.807 0 0 12 0.818 24.38 60 7.8 464 1.33 7 0 0 1.46 0 12
0.305 26.24 60 7.8 432 1.61 8 0 0 0 3.706 12 0.869 23.43 60 7.8 436
1.84
[0060] The formulations shown in Table 3 were prepared, and TiN and
Cu etch rate evaluations were carried out as described above at a
temperature of 50.degree. C. and pH of 8. The removal compositions
demonstrated a higher TiN etch rate and similar copper etch rate
when compared to the control, composition 9, that did not contain
an ammonium carboxylate.
TABLE-US-00003 TABLE 3 Saturated Ammonium Ammonium Ammonium
Tetrabutylphosphonium Carbonate Acetate Oxalate BTA Hydroxide
H.sub.2O.sub.2 TiN (.ANG./min) Cu (.ANG./min) Test (10%) (10%)
(5.5%) (1.5%) (40%) DIW (30%) pH at 50.degree. C. at 50.degree. C.
9 0 0 0 12 1.592 26.41 60 8 68 0.99 10 1.46 0 0 12 0.998 25.54 60 8
170 0.94 11 0 1.172 0 12 1.575 25.25 60 8 150 1.28 12 0 0 1.887 12
1.530 24.58 60 8 154 1.17
[0061] The formulations shown in Table 4 were prepared using DGA to
adjust the pH, and BTA was used as the copper corrosion inhibitor.
TiN and Cu etch rate evaluations were carried out as described
above at a temperature of 50.degree. C. and pH of 8. The removal
compositions demonstrated a higher TiN etch rate and a similar Cu
etch rate when compared to the control, composition 13, that did
not contain an ammonium carboxylate.
TABLE-US-00004 TABLE 4 Saturated Ammonium Ammonium Ammonium
Carbonate Acetate Oxalate BTA DGA H.sub.2O.sub.2 TIN (.ANG./min) Cu
(.ANG./min) Test (10%) (10%) (5.5%) (1.5%) (10%) DIW (30%) pH at
50.degree. C. at 50.degree. C. 13 0 0 0 12 2.645 25.36 60 7.9 98
0.33 14 1.46 0 0 12 1.790 24.75 60 8.0 147 1.62 15 0 1.172 0 12
2.601 24.23 60 8.0 146 0.2 16 0 0 1.887 12 2.502 23.61 60 7.9 140
0.83
[0062] The formulations shown in Table 5 were prepared using TMAH
to adjust the pH, and BTA was used as the copper corrosion
inhibitor. TiN and Cu etch rate evaluations were carried out as
described above at a temperature of 50.degree. C. and pH of 8. The
removal compositions demonstrated a higher TiN etch rate and a
similar Cu etch rate when compared to the control, composition 17,
that did not contain an ammonium carboxylate.
TABLE-US-00005 TABLE 5 Saturated TiN Cu Ammonium Ammonium Ammonium
(.ANG./min) (.ANG./min) Carbonate Acetate Oxalate BTA TMAH
H.sub.2O.sub.2 at at Test (10%) (10%) (5.5%) (1.5%) (25%) DIW (30%)
pH 50.degree. C. 50.degree. C. 17 0 0 0 12 0.975 27.03 60 8 99 0.12
18 1.46 0 0 12 0.611 25.93 60 8 200 1.85 19 0 1.172 0 12 0.866
25.96 60 8 191 1.08 20 0 0 1.887 12 0.828 25.29 60 8 197 1.53
[0063] The formulations shown in Table 6 were prepared using
benzyltrimethylammonium hydroxide (BTAH) to adjust the pH, and BTA
was used as the copper corrosion inhibitor. TiN and Cu etch rate
evaluations were carried out as described above at a temperature of
50.degree. C. and pH of about 8. The removal compositions
demonstrated a higher TiN etch rate and a similar Cu etch rate when
compared to the control, composition 21, that did not contain an
ammonium carboxylate.
TABLE-US-00006 TABLE 6 Saturated Benzyltri- TiN Cu Ammonium
Ammonium Ammonium methylammonium (.ANG./min) (.ANG./min) Carbonate
Acetate Oxalate BTA Hydroxide H.sub.2O.sub.2 at at Test (10%) (10%)
(5.5%) (1.5%) (40%) DIW (30%) pH 50.degree. C. 50.degree. C. 21 0 0
0 12 1.127 26.87 60 8 100 0.7 22 1.46 0 0 12 0.744 25.80 60 8 178
0.63 23 0 1.172 0 12 1.078 25.75 60 8 174 0.54 24 0 0 1.887 12
1.036 25.08 60 8 164 0.75
[0064] The formulations shown in Table 7 were prepared using
tetraethylammonium hydroxide (TEAH) to adjust the pH, and BTA was
used as the copper corrosion inhibitor. TiN and Cu etch rate
evaluations were carried out as described above at a temperature of
50.degree. C. and pH of 8. The removal compositions demonstrated a
higher TiN etch rate and a similar Cu etch rate when compared to
the control, composition 25, that did not contain an ammonium
carboxylate.
TABLE-US-00007 TABLE 7 Saturated Ammonium TiN Cu Ammonium Ammonium
Ammonium Citrate Ammonium (.ANG./min) (.ANG./min) Carbonate Acetate
Oxalate Tribasic Tartrate BTA TEAH H.sub.2O.sub.2 at at Test (10%)
(10%) (5.5%) (10%) (10%) (1.5%) (20%) DIW (30%) pH 50.degree. C.
50.degree. C. 25 0 0 0 0 0 12 2.46 25.54 60 8 94 0.39 26 1.46 0 0 0
0 12 1.64 24.90 60 8 214 0.92 27 0 1.172 0 0 0 12 2.66 24.17 60 8
218 0.01 28 0 0 1.887 0 0 12 2.74 23.37 60 8 197 -0.72 29 0 0 0
3.706 0 12 2.60 21.69 60 8 235 -0.46 30 0 0 0 0 2.807 12 2.53 22.66
60 8 209 0.03
[0065] The formulations shown in Table 8 were prepared using DGA to
adjust the pH, but no copper corrosion inhibitor was used. TiN and
TEOS removal rate evaluations were carried out as described above
at a temperature of 50.degree. C. and pH of about 8. The removal
compositions demonstrated a high TiN etch rate in the range of from
a low of 144 .ANG./min to a high of 179 .ANG./min when compared to
the control, composition 31, which had a TiN etch rate of 87
.ANG./min. The presence of the compounds ammonium carbonate,
ammonium acetate, ammonium oxalate, ammonium lactate and ammonium
tartrate at concentrations of from 1.46 wt % to less than 3 wt %
operate to provide the removal compositions of the invention with
the capability to deliver very high TiN etch rates at relatively
low temperature, e.g., 50.degree. C. It is noteworthy according to
the described and claimed inventive concepts that none of the
compounds ammonium carbonate, ammonium acetate, ammonium oxalate,
ammonium lactate or ammonium tartrate had significant effect on
TEOS removal rate when compared to the control, composition 31.
TABLE-US-00008 TABLE 8 Saturated TiN TEOS Ammonium Ammonium
Ammonium Ammonium Ammonium (.ANG./min) (.ANG./min) Carbonate
Acetate Oxalate Lactate Tartrate DGA H.sub.2O.sub.2 at at Test
(10%) (10%) (5.5%) (10%) (10%) (10%) DIW (30%) pH 50.degree. C.
50.degree. C. 31 0 0 0 0 0 2.65 37.35 60 7.93 87 0.01 32 1.46 0 0 0
0 1.52 37.02 60 7.94 161 0.2 33 0 1.172 0 0 0 2.37 36.46 60 7.90
165 -0.1 34 0 0 1.887 0 0 2.38 35.73 60 7.90 144 0.61 35 0 0 0
1.632 0 0.94 37.43 60 7.91 181 0.48 36 0 0 0 0 2.807 2.19 35.00 60
7.91 179 0.07
[0066] The formulations shown in Table 9 were prepared without the
use of a pH adjustment agent. The Cu corrosion inhibitor used was
Wintrol A-90, a commercial mixture of BTA and tolyltriazole. The
desired TiN and Cu etch rates and pH were obtained by varying
hydrogen peroxide and ammonium carboxylate concentrations. In these
examples, several carboxylates in various concentrations were used.
Hydrogen peroxide concentration was either 20 wt % or 80 wt %. The
formulation pH's ranged from a low of pH 5 up to pH 8.4, and the
TiN etch rate, i.e., the removal rate, ranged from a low of 18
.ANG./min up to 170 .ANG./min.
TABLE-US-00009 TABLE 9 Saturated TiN Cu Ammonium Ammonium Ammonium
Ammonium Wintrol (.ANG./min) (.ANG./min) Carbonate Acetate Oxalate
Lactate A- H.sub.2O.sub.2 at at Test (10%) (10%) (5.5%) (10%) 90
DIW (30%) pH 50.degree. C. 50.degree. C. 37 1.46 0 0 0 0.8 77.74 20
7.9 65 -0.81 38 2.92 0 0 0 0.8 76.28 20 8.3 82 -2.61 39 4.38 0 0 0
0.8 74.82 20 8.4 88 0.02 40 0 1.172 0 0 0.8 78.03 20 6.1 18 -1.75
41 0 0 1.887 0 0.8 77.31 20 5.6 19 0.19 42 0 0 0 1.632 0.8 77.57 20
7.8 55 -1.3 43 1.46 0 0 0 0.8 17.74 80 6.8 133 0.34 44 0 1.172 0 0
0.8 18.03 80 5.5 69 -0.41 45 0 0 1.887 0 0.8 17.31 80 5.0 71 -0.85
46 0 0 0 1.632 0.8 17.57 80 7.0 170 0.26
[0067] The formulations shown in Table 10 were prepared with
tartaric acid, or TMAH, or without any pH adjustment agent. Wintrol
A-90 was used as a Co corrosion inhibitor. In these examples,
several carboxylates in various concentrations were used. Hydrogen
peroxide concentration ranged from 20 wt % to 80 wt %. The
formulation pH ranged from a low of pH 5 up to pH 11. The Co etch
rate was insignificant in all cases (i.e., the highest Co etch rate
was 1.17 .ANG./min).
TABLE-US-00010 TABLE 10 Saturated Co Ammonium Ammonium Ammonium
Ammonium Wintrol Tartaric (.ANG./min) Tartrate Lactate Oxalate
Carbonate A- Acid TMAH H.sub.2O.sub.2 at Test (10%) (10%) (5.5%)
(10%) 90 (10%) (25%) DIW (30%) pH 50.degree. C. 47 0 1.632 0 0 0.8
0.880 0 36.69 60 5.0 -0.01 48 2.807 0 0 0 0.8 0.036 0 36.36 60 5.0
0.31 49 0 0 1.887 0 0.8 0 0 17.31 80 5.0 0.09 50 0 0 1.887 0 0.8 0
20.41 56.90 20 11.0 1.04 51 0 0 0 1.46 0.8 0 0 17.74 80 6.8 0.27 52
0 0 0 1.46 0.8 0 20.66 57.08 20 11.0 1.17
[0068] The results shown in Table 11, below, indicate that a
mixture of ammonium lactate and ammonium tartrate in removal
composition 54 exhibited a higher TiN etch rate when compared to
the control, composition 53, which contained no ammonium
carboxylate.
TABLE-US-00011 TABLE 11 TiN Cu Co Ammonium Ammonium (.ANG./min)
(.ANG./min) (.ANG./min) Lactate Tartrate BTA TMAH H.sub.2O.sub.2 at
at at Test (10%) (10%) (1.5%) (25%) DIW (30%) pH 50.degree. C.
50.degree. C. 50.degree. C. 53 0 0 12 1.28 26.72 60 8 135 -0.1 0.3
54 0.041 0.702 12 1.49 25.77 60 8 203 0.2 0.8
[0069] The formulations shown in Table 12 were prepared using TMAH
to adjust the pH, and BTA was used as copper corrosion inhibitor.
Carboxylates used were potassium citrate tribasic monohydrate,
potassium sodium tartrate tetrahydrate, and potassium L-lactate in
compositions 56, 57 and 58, respectively. Each of these
compositions demonstrated a higher TiN etch rate and a similar Cu
etch rate when compared to the control, composition 55, that did
not contain a carboxylate.
TABLE-US-00012 TABLE 12 Potassium Potassium Citrate Sodium TiN Cu
Tribasic Tartrate Potassium (.ANG./min) (.ANG./min) Monohydrate
Tetrahydrate L-Lactate BTA TMAH H.sub.2O.sub.2 at at Test (100%)
(100%) (60%) (1.5%) (25%) DIW (30%) pH 50.degree. C. 50.degree. C.
55 0 0 0 12 1.266 26.73 60 8.0 110 0.1 56 0.4944 0 0 12 1.194 26.31
60 8.0 192 1.5 57 0 0.432 0 12 1.266 26.30 60 8.0 175 -0.1 58 0 0
0.3256 12 1.252 26.42 60 8.0 167 0.1
[0070] The results shown in Table 13 indicate that at ammonium
carboxylate concentrations as low as 0.001 wt %, removal
compositions 60 through 63 exhibited higher TiN etch rates and
similar Cu and Co etch rates when compared to the control,
composition 59
TABLE-US-00013 TABLE 13 Ammonium TiN Cu Co Ammonium Ammonium
Ammonium Citrate (.ANG./min) (.ANG./min) (.ANG./min) Lactate
Tartrate Carbonate Tribasic BTA TMAH H.sub.2O.sub.2 at at at Test
(10%) (10%) (10%) (10%) (1.5%) (25%) DIW (30%) pH 50.degree. C.
50.degree. C. 50.degree. C. 59 0 0 0 0 12 1.30 26.70 60 8 86 0.3
0.7 60 0.01 0 0 0 12 1.69 26.30 60 8 93 0.2 0.6 61 0 0.01 0 0 12
1.51 26.48 60 8 107 0.0 0.6 62 0 0 0.01 0 12 1.53 26.46 60 8 119
0.4 0.6 63 0 0 0 0.01 12 1.37 26.62 60 8 102 0.1 0.4
[0071] The results shown in Table 14 indicate that at an ammonium
acetate concentration of 50 wt %, removal composition 65 exhibited
a higher TiN etch rate and similar Cu and Co etch rates when
compared to the control, composition 64, which contained no
ammonium carboxylate.
TABLE-US-00014 TABLE 14 TiN Cu Co Ammonium (.ANG./min) (.ANG./min)
(.ANG./min) Acetate BTA DGA H.sub.2O.sub.2 at at at Test (100%)
(1.5%) (10%) DIW (30%) pH 30.degree. C. 30.degree. C. 30.degree. C.
64 0 12 1.060 56.94 30 7.8 8 0.3 0.1 65 50 12 4.450 3.55 30 7.8 18
1.6 0.3
Tungsten (W) Etch Rate
[0072] The formulations shown in Table 15 were prepared, and W
(tungsten) etch rate evaluations were carried out at temperatures
of 45.degree. C. and 55.degree. C. as described above in connection
with TiN removal.
TABLE-US-00015 TABLE 15 Saturated W Ammonium Ammonium Ammonium
Ammonium Tartaric (.ANG./min) Carbonate Acetate Oxalate Tartrate
DGA TMAH Acid H.sub.2O.sub.2 at Test (10%) (10%) (5.5%) (10%) (10%)
(25%) (10%) DIW (30%) pH 45.degree. C. 66 0 0 0 0 2.645 0 0.00 37.4
60 7.9 173 67 1.46 0 0 0 1.790 0 0.00 36.8 60 8.0 401 68 0 1.172 0
0 2.601 0 0.00 36.2 60 8.0 444 69 0 0 1.887 0 2.502 0 0.00 35.6 60
7.9 361 70 0 0 0 0 0.000 19.517 0.00 20.5 60 11.1 365 71 0 0 0 3
0.000 20.272 0.00 16.7 60 11.1 771 72 0 0 0 0 0.000 0 0.42 40.0 60
3.9 751 (55.degree. C.) 73 0 0 0 3 0.000 0 0.48 36.5 60 3.9 1046
(55.degree. C.)
[0073] The presence of ammonium carboxylate at a concentration of
1.46 wt % to 3 wt % and at a pH ranging from about 4 to slightly
higher than 11 was shown to significantly increase the W removal
rate when compared to the corresponding ammonium carboxylate-free
control compositions 66, 70 and 72 at the same pH.
Composition Stability
[0074] As noted above, the presence of an amino acid, amine
polycarboxylic acid (i.e., aminopolycarboxylic acid), and/or
carboxylic acid, polycarboxylic acid chelating agent, or a mixture
thereof, was observed to unexpectedly stabilize the compositions of
the invention. The term "stabilize" is used herein to mean that the
achievable etch rate for a hard mask, i.e., the rate at which
hardmask is removed, remains substantially constant over an
extended period of time, e.g., a time period of from twenty two
(22) hours up to at least thirty five (35) hours at the selected
operating temperature. As used herein the term "substantially
constant" is intended to mean that the achievable etch rate at
which hard mask is removed does not drop more than 15 .ANG./min
during the useful life of the composition at the selected operating
temperature. Examples of chelating agents which are operable
according to the described and claimed inventive concepts include,
but are not limited to,
1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid (CDTA);
ethylenediaminetetraacetic acid; nitrilotriacetic acid; diethylene
triamine pentaacetic acid;
1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; ethylene
glycol tetraacetic acid (EGTA);
1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid;
N-{2-[bis(carboxymethyl)amino]ethyl}-N-(2-hydroxyethyl)glycine
(HEDTA); and ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)
(EDDHA).
[0075] Pot life is a measure of the ability of the removal
composition formula to perform optimally over time and without
significant variation in functionality over time. Pot life is a
strong function of temperature. After many hours of treatment at
high temperature, the chemicals in the mixture can decompose and
the formula will lose functionality.
[0076] Pot life studies were conducted (to confirm the period of
time during which, and the extent to which, the etch rates of the
removal compositions of the invention remained constant) as
follows: 800 gram stock solutions were prepared and maintained at
50.degree. C. 150 gram samples were removed from the heated stock
solution and used for TiN and Cu etch rate and pH studies at
specific times at 50.degree. C. The samples were discarded after
each etch rate measurement.
[0077] Removal compositions were prepared according to the
described and claimed inventive concept(s) wherein ammonium
tartrate was selected as the ammonium carboxylate at a
concentration of 0.3 wt %.
1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid (CDTA) was
selected as the aminopolycarboxylic acid chelating agent in
formulation 74 and 75, and no chelating agent was included in the
control formulation 76. The compositions are shown in Table 16.
[0078] Samples were taken from the removal compositions at
intervals of 0, 2, 4, 7.5 and 22 hours to measure TiN and Cu etch
rates. Results are shown in Table 17.
TABLE-US-00016 TABLE 16 Ammonium Tartrate CDTA TEAH BTA
H.sub.2O.sub.2 Test (10%) Pyrazole (100%) (20%) (1.5%) DIW (30%) pH
74 3 0.3 0.200 3.122 12.120 21.258 60 8.07 75 3 0.3 0.607 5.482
12.120 18.491 60 8.05 76 3 0.3 0.000 2.220 12.120 22.36 60 8.15
TABLE-US-00017 TABLE 17 TiN (.ANG./min) Cu (.ANG./min) Test Time
(hr) at 50.degree. C. at 50.degree. C. 74 0 168.1 0.12 75 157.0
0.03 76 219.0 -0.02 74 2 166.0 0.53 75 143.7 0.46 76 211.2 0.45 74
4 163.7 1.42 75 155.5 0.90 76 203.6 0.62 74 7.5 159.4 0.77 75 157.4
1.11 76 166.6 -0.02 74 22 156.6 0.53 75 156.4 1.47 76 99.9 0.52
[0079] The data presented in Table 17 demonstrates that with CDTA
in removal compositions 74 and 75, the TiN etch rate remained
stable, i.e., substantially constant, over a period of 22 hours.
The initial TiN etch rate was 157 .ANG./min, and it remained at 156
.ANG./min for composition 75 over a 22 hour period. For composition
74 the initial TiN etch rate was 168 .ANG./min and remained at 157
.ANG./min over a 22 hour period. In composition 76, without CDTA,
the TiN etch rate declined from an initial etch rate of 219
.ANG./min to an etch rate of 99 .ANG./min after 22 hours.
[0080] Removal compositions were prepared according to the
described and claimed inventive concept(s) wherein ammonium
tartrate was selected as the ammonium carboxylate at a
concentration of 0.3 wt %.
1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid (CDTA) was
selected as the aminopolycarboxylic acid chelating agent in
formulation 77 and 78. The compositions are shown in Table 18.
[0081] Samples were taken from the removal compositions at
intervals of 0, 2, 4, 7 and 24 hours to measure TiN and Cu etch
rates. Results are shown in Table 19.
TABLE-US-00018 TABLE 18 Ammonium Tartrate CDTA TEAH BTA
H.sub.2O.sub.2 Test (10%) Pyrazole (100%) (20%) (1.5%) DIW (30%) pH
77 3 0.3 0.001 0.404 12.12 74.18 10 8 78 3 0.3 0.005 0.632 12.12
73.94 10 8.13
TABLE-US-00019 TABLE 19 Time TiN (.ANG./min) Cu (.ANG./min) Test
(hrs) at 50.degree. C. at 50.degree. C. 77 0 27.33 1.02 78 26.91
-0.425 77 4 27.56 0.55 78 26.23 -1.41 77 7 25.65 0.61 78 26.65
0.835 77 24 24.41 1.06 78 26.24 1.56
[0082] The data presented in Table 19 demonstrate that with 0.001%
and 0.005% of CDTA in removal compositions 77 and 78, respectively,
the TiN etch rate remained stable, i.e., substantially constant,
over a period of 24 hours. The initial TiN etch rate was 27.33
.ANG./min, and it remained at 24.41 .ANG./min for composition 77
over a 24 hour period. For composition 78, the initial TiN etch
rate was 26.91 .ANG./min and remained at 26.24 .ANG./min over a 24
hour period.
[0083] The formulations shown in Table 20 were prepared using DGA
to adjust the pH, and BTA was used as copper corrosion inhibitor.
Tetraammonium EDTA was used to stabilize the TiN etch rate.
[0084] A pot life study was conducted according to the method
described above. Samples were taken at intervals of 0, 2, 4, 8, 24,
28 and 35 hours to measure TiN and Cu etch rates and pH. Results
are shown in Table 21.
TABLE-US-00020 TABLE 20 Ammonium Tartrate DGA Tetraammonium BTA
H.sub.2O.sub.2 Test (10%) Pyrazole (10%) EDTA (10%) (1.5%) DIW
(30%) pH 79 0 0.3 1.400 8 12.12 18.18 60 7.9 80 3 0.3 3.330 0 12.12
21.25 60 7.9
TABLE-US-00021 TABLE 21 TiN (.ANG./min) Cu (.ANG./min) Test Time
(hr) at 50.degree. C. at 50.degree. C. pH 79 0 208 1.9 7.45
(46.9.degree. C.) 80 209 1.0 7.56 (47.0.degree. C.) 79 2 217 0.4
7.43 (46.2.degree. C.) 80 163 0.2 7.49 (46.3.degree. C.) 79 4 205
1.0 7.34 (47.0.degree. C.) 80 150 0.4 7.33 (46.4.degree. C.) 79 8
214 1.4 7.31 (47.4.degree. C.) 80 143 0.4 6.99 (47.5.degree. C.) 79
24 218 1.2 7.22 (46.6.degree. C.) 80 106 0.3 6.61 (46.3.degree. C.)
79 28 190 0.7 7.21 (46.0.degree. C.) 80 N/A N/A N/A 77 35 194 1.0
7.20 (47.1.degree. C.) 80 N/A N/A N/A
[0085] The experimental results shown in Table 21 demonstrate that
with tetraammonium EDTA in removal composition 79, the TiN etch
rate remained stable, i.e., remained substantially constant, over a
period of thirty five (35) hours. The initial TiN etch rate was 208
.ANG./min, and it remained at 194 .ANG./min over the thirty five
(35) hour period. In composition 80, without tetraammonium EDTA,
the TiN etch rate dropped from an initial rate of 209 .ANG./min to
a rate of 106 .ANG./min after 24 hours.
[0086] The formulations in Table 22 were prepared using DGA to
adjust pH. BTA was used as copper corrosion inhibitor. The ammonium
carboxylate selected was tetraammonium EDTA. The results shown in
Table 22 indicate that tetraammonium EDTA in removal composition 81
exhibited a higher TiN etch rate when compared to the control,
composition 82, which contained no ammonium carboxylate.
TABLE-US-00022 TABLE 22 TiN Cu (.ANG./min) (.ANG./min) DGA
Tetraammonium BTA H.sub.2O.sub.2 at at Test Pyrazole (10%) EDTA
(10%) (1.5%) DIW (30%) 50.degree. C. 50.degree. C. pH 81 0.3 1.740
6.0 12.12 19.84 60 233 1.97 7.9 82 0.3 3.360 0.0 12.12 24.22 60 134
0.18 7.9
[0087] The presence of ammonium carboxylate in the removal
compositions of the invention not only increased TiN etch rate as
shown in Tables 2 through 8, 11, 13 through 15, and 22, but the
data support the conclusion that their presence also operates to
stabilize the TiN etch rate over an extended period of time, e.g.,
up to at least 35 hrs.
[0088] Several embodiments of the inventive concepts have been
described. However, those ordinarily skilled in the art will
recognize that the invention is not limited to the embodiments
described. The inventive concepts can be practiced with
modifications and alteration within the spirit and scope of the
appended claims.
* * * * *