U.S. patent application number 16/765371 was filed with the patent office on 2020-10-29 for composition and process for selectively etching a layer comprising an aluminium compound in the presence of layers of low-k materials, copper and/or cobalt.
This patent application is currently assigned to BASF SE. The applicant listed for this patent is BASF SE. Invention is credited to Yi Ping CHENG, Joannes Theodorus Valentinus HOOGBOOM, Jhih Jheng KE, Andreas KLIPP, Che Wei WANG.
Application Number | 20200339523 16/765371 |
Document ID | / |
Family ID | 1000005020067 |
Filed Date | 2020-10-29 |
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United States Patent
Application |
20200339523 |
Kind Code |
A1 |
HOOGBOOM; Joannes Theodorus
Valentinus ; et al. |
October 29, 2020 |
COMPOSITION AND PROCESS FOR SELECTIVELY ETCHING A LAYER COMPRISING
AN ALUMINIUM COMPOUND IN THE PRESENCE OF LAYERS OF LOW-K MATERIALS,
COPPER AND/OR COBALT
Abstract
A composition for selectively etching a layer comprising an
aluminium compound in the presence of a layer of a low-k material
and/or a layer comprising copper and/or cobalt is described, and a
corresponding use of said composition. Further is described a
process for the manufacture of a semiconductor device, comprising
the step of selectively etching at least one layer comprising an
aluminium compound in the presence of a layer of a low-k material
and/or a layer comprising copper and/or cobalt by contacting the at
least one layer comprising an aluminium compound with the described
composition.
Inventors: |
HOOGBOOM; Joannes Theodorus
Valentinus; (Ludwigshafen, DE) ; KE; Jhih Jheng;
(Taoyuan, TW) ; WANG; Che Wei; (Taoyuan, TW)
; KLIPP; Andreas; (Ludwigshafen, DE) ; CHENG; Yi
Ping; (Taoyuan, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BASF SE |
Ludwigshafen am Rhein |
|
DE |
|
|
Assignee: |
BASF SE
Ludwigshafen am Rhein
DE
|
Family ID: |
1000005020067 |
Appl. No.: |
16/765371 |
Filed: |
December 5, 2018 |
PCT Filed: |
December 5, 2018 |
PCT NO: |
PCT/EP2018/083683 |
371 Date: |
May 19, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23F 1/44 20130101; H01L
21/31111 20130101; C23F 1/20 20130101; C07D 265/30 20130101 |
International
Class: |
C07D 265/30 20060101
C07D265/30; C23F 1/44 20060101 C23F001/44; C23F 1/20 20060101
C23F001/20; H01L 21/311 20060101 H01L021/311 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 2017 |
EP |
17206096.4 |
Jun 28, 2018 |
EP |
18180361.0 |
Claims
1. A composition comprising: (A) at least one solubilizer, selected
from the group consisting of a compound of formula I: ##STR00005##
wherein R.sup.1 is at least one selected from the group consisting
of hydrogen and --C(O)--R.sup.2 wherein R.sup.2 is selected from
the group consisting of hydrogen and alkyl having 1, 2, 3 or 4
carbon atoms; a compound of formula II: ##STR00006## wherein
R.sup.3 is alkyl having 1, 2, 3 or 4 carbon atoms;
trimethylamine-N-oxide, triethylamine-N-oxide,
triethanolamine-N-oxide, pyridine-N-oxide, and
N-ethylpyrrolidine-N-oxide; (B) an etchant comprising fluoride
anions; (C) at least one corrosion inhibitor, selected from the
group consisting of benzotriazole which is unsubstituted or
substituted once or twice independently by C.sub.1-4-alkyl,
amino-C.sub.1-4-alkyl, phenyl, thiophenyl, halogen, hydroxy, nitro
and/or thiol; ethylene urea, ethylene thiourea, 1,2,4-triazole,
5-aminotetrazole, 5-amino-1,3,4-thiadiazol-2-thiol,
3-amino-1H-1,2,4 triazole, 3,5-diamino-1,2,4-triazole,
tolyltriazole, 3-amino-5-mercapto-1,2,4-triazole,
1-amino-1,2,4-triazole, 1-amino-1,2,3-triazole,
1-amino-5-methyl-1,2,3-triazole, 3-mercapto-1,2,4-triazole,
3-isopropyl-1,2,4-triazole, naphthotriazole, 1 H-tetrazole-5-acetic
acid, 1-phenyl-2-tetrazoline-5-thione, 4-methyl-2-phenylimidazole,
2-mercaptothiazoline, 2,4-diamino-6-methyl-1,3,5-triazine,
thiazole, imidazole, benzimidazole, triazine, methyltetrazole,
1,3-dimethyl-2-imidazolidinone, 1,5-pentamethylenetetrazole,
1-phenyl-5-mercaptotetrazole, 2H-imidazole-2-thione,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, tritolyl
phosphate, indazole, adenine, cytosine, guanine, thymine,
2,2'-azanediyldiacetic acid, propanethiol, citric acid, ascorbic
acid, thiourea, 1,1,3,3-tetramethylurea, urea, uric acid, glycine,
dodecylphosphonic acid, oxalic acid, malonic acid, succinic acid,
and nitrilotriacetic acid; (D) at least one chelating agent
selected from the group consisting of histidine,
1,2-cyclohexylenedinitrilotetraacetic acid,
1,1,1,5,5,5-hexafluoro-2,4-pentanedione, acetylacetonate,
2,2'-azanediyldiacetic acid, ethylenediaminetetraacetic acid,
etidronic acid, methanesulfonic acid, acetylacetone,
1,1,1-trifluoro-2,4-pentanedione, 1,4-benzoquinone,
8-hydroxyquinoline, salicylidene aniline;
tetrachloro-1,4-benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol,
2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid,
sulfosalicylic acid, salicylic acid, pyridine, 2-ethylpyridine,
2-methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine,
piperidine, piperazine, triethylamine, triethanolamine, ethylamine,
methylamine, isobutylamine, tert-butylamine, tributylamine,
dipropylamine, dimethylamine, diglycol amine, monoethanolamine,
methyldiethanolamine, pyrrole, isoxazole, bipyridine, pyrimidine,
pyrazine, pyridazine, quinoline, isoquinoline, indole,
1-methylimidazole, diisopropylamine, diisobutylamine, aniline,
pentamethyldiethylenetriamine, acetoacetamide, ammonium carbamate,
ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl
acetoacetate, N-methyl acetoacetamide, tetramethylammonium
thiobenzoate, 2,2,6,6-tetramethyl-3,5-heptanedione,
tetramethylthiuram disulfide, lactic acid, ammonium lactate, formic
acid, propionic acid, and gamma-butyrolactone; and (G) water.
2. The composition according to claim 1, wherein the at least one
solubilizer (A) is selected from the group consisting of a compound
of formula I; and a compound of formula II; the etchant (B) is at
least one selected from the group consisting of ammonium fluoride,
ammonium bifluoride, triethanolammonium fluoride, diglycolammonium
fluoride, methyldiethanolammonium fluoride, tetramethylammonium
fluoride, triethylamine trihydrofluoride, hydrogen fluoride,
fluoroboric acid, tetrafluoroboric acid, ammonium
tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate,
trifluoroacetic acid, fluorosilicic acid, ammonium fluorosilicate,
and tetrabutylammonium tetrafluoroborate; and/or the at least one
corrosion inhibitor (C) is selected from the group consisting of
benzotriazole which is unsubstituted or substituted once or twice
independently by C.sub.1-4-alkyl, amino-C.sub.1-4-alkyl, phenyl,
thiophenyl, halogen, hydroxy, nitro and/or thiol; succinic
acid.
3. The composition according to claim 1, wherein the at least one
chelating agent (D) is selected from the group consisting of
histidine and 1,2-cyclohexylenedinitrilotetraacetic acid, and/or
the composition comprises as further component: (E) a
surfactant.
4. The composition according to claim 1, wherein a pH of the
composition is in the range of from 3.5 to 8, and/or the
composition comprises as further component: (F) a buffering system
which is suitable to buffer a pH of the composition in the range of
from 3.5 to 8.
5. The composition according to claim 1, comprising (A) at least
one solubilizer selected from the group consisting of a compound of
formula I, and a compound of formula II; (B) at least one etchant,
selected from the group consisting of ammonium fluoride, ammonium
bifluoride, triethanolammonium fluoride, diglycolammonium fluoride,
methyldiethanolammonium fluoride, tetramethylammonium fluoride,
triethylamine trihydrofluoride, hydrogen fluoride, fluoroboric
acid, tetrafluoroboric acid, ammonium tetrafluoroborate,
fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid,
fluorosilicic acid, ammonium fluorosilicate, and tetrabutylammonium
tetrafluoroborate; (C) at least one corrosion inhibitor, selected
from the group consisting of benzotriazole which is unsubstituted
or substituted once or twice independently by C.sub.1-4-alkyl,
amino-C.sub.1-4-alkyl, phenyl, thiophenyl, halogen, hydroxy, nitro
and/or thiol, and succinic acid (D) at least one chelating agent
selected from the group consisting of histidine, and
1,2-cyclohexylenedinitrilotetraacetic acid and (G) water, wherein a
pH of the composition is in the range of from 3.5 to 8.
6. The composition according to claim 1, the composition
comprising: (A) at least one solubilizer, selected from the group
consisting of 4-methylmorpholine-4-oxide, trimethylamine-N-oxide,
triethylamine-N-oxide, triethanolamine-N-oxide, pyridine-N-oxide,
N-ethylmorpholine-N-oxide, and N-ethylpyrrolidine-N-oxide and
mixtures thereof; (B) an etchant comprising fluoride anions; (C) at
least one corrosion inhibitor, selected from the group consisting
of benzotriazole, 6-methyl-benzotriazole, 5-methyl-benzotriazole,
ethylene urea, ethylene thiourea, 1,2,4-triazole, 5-aminotetrazole,
1-hydroxybenzotriazole, 5-amino-1,3,4-thiadiazol-2-thiol,
3-amino-1H-1,2,4 triazole, 3,5-diamino-1,2,4-triazole,
tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole,
3-amino-5-mercapto-1,2,4-triazole, 1 -amino-1,2,4-triazole,
2-(5-amino-pentyl)-benzotriazole, 1 -amino-1,2,3-triazole, 1
-amino-5-methyl-1,2,3-triazole, 3-mercapto-1,2,4-triazole,
3-isopropyl-1,2,4-triazole, 5-phenylthiol-benzotriazole,
halobenzotriazoles, naphthotriazole, 1 H-tetrazole-5-acetic acid,
2-mercaptobenzothiazole, 1-phenyl-2-tetrazoline-5-thione,
2-mercaptobenzimidazole, 4-methyl-2-phenylimidazole,
2-mercaptothiazoline, 2,4-diamino-6-methyl-1,3,5-triazine,
thiazole, imidazole, benzimidazole, triazine, methyltetrazole,
1,3-dimethyl-2-imidazolidinone, 1,5-pentamethylenetetrazole,
1-phenyl-5-mercaptotetrazole, 2H-imidazole-2-thione,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzo-thiazole, tritolyl
phosphate, indazole, adenine, cytosine, guanine, thymine,
2,2'-azanediyldiacetic acid, propanethiol, citric acid, ascorbic
acid, thiourea, 1,1,3,3-tetramethylurea, urea, uric acid, glycine,
dodecylphosphonic acid, oxalic acid, malonic acid, succinic acid,
and nitrilotriacetic acid; (D) at least one chelating agent
selected from the group consisting of
1,2-cyclohexylenedinitrilotetraacetic acid,
1,1,1,5,5,5-hexafluoro-2,4-pentane-dione, acetylacetonate,
2,2'-azanediyldiacetic acid, ethylenediaminetetraacetic acid,
etidronic acid, methanesulfonic acid, acetylacetone,
1,1,1-trifluoro-2,4-pentanedione, 1,4-benzoquinone,
8-hydroxyquinoline, salicylidene aniline;
tetrachloro-1,4-benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol,
2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid,
sulfosalicylic acid, salicylic acid, pyridine, 2-ethylpyridine,
2-methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine,
piperidine, piperazine, triethylamine, triethanolamine, ethylamine,
methylamine, isobutylamine, tert-butylamine, tributylamine,
dipropylamine, dimethylamine, diglycol amine, monoethanolamine,
methyldiethanolamine, pyrrole, isoxazole, bipyridine, pyrimidine,
pyrazine, pyridazine, quinoline, isoquinoline, indole, 1
-methylimidazole, diisopropylamine, diisobutylamine, aniline,
pentamethyldiethylenetriamine, acetoacetamide, ammonium carbamate,
ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl
acetoacetate, N-methyl acetoacetamide, tetramethylammonium
thiobenzoate, 2,2,6,6-tetramethyl-3,5-heptanedione,
tetramethylthiuram disulfide, lactic acid, ammonium lactate, formic
acid, propionic acid, and gamma-butyrolactone; (E) at least one
surfactant; (F) a buffering system which is suitable to buffer a pH
of the composition in the range of from 6 to 8, and (G) water,
wherein the pH of the composition is in the range of from 6 to
8.
7. The composition according to claim 3, wherein the total amount
of the at least one solubilizer (A) present is in the range of from
0.01 to 20 wt. % based on the total weight of the composition.
8. The composition according to claim 5, wherein the total amount
of the at least one etchant (B) present is in the range of from
0.001 to 1 wt. % based on the total weight of the composition.
9. The composition according to claim 1, wherein the total amount
of the at least one corrosion inhibitor (C) present is in the range
of from 0.01 to 4 wt.-% based on the total weight of the
composition.
10. A method comprising: contacting the composition according to
claim 1 with a substrate, wherein the method is suitable for
selectively etching a layer comprising an aluminium compound in the
presence of a layer of a low-k material and/or a layer comprising
copper and/or cobalt; for selectively removing from a substrate a
layer comprising an aluminium compound in the presence of a layer
of a low-k material and/or a layer comprising copper and/or cobalt,
and/or for selectively removing from the surface of a semiconductor
substrate a layer comprising an aluminium compound in the presence
of a layer of a low-k material and/or a layer comprising copper
and/or cobalt.
11. The method according to claim 10, wherein the method comprises
a two-step-process of removing (i) a metal hard mask, and (ii) an
etch-stop layer of an aluminium compound deposited on a layer
comprising copper and/or a layer comprising cobalt.
12. A process for manufacturing a semiconductor device, the process
comprising: selectively etching at least one layer comprising or
consisting of an aluminium compound in the presence of a layer of a
low-k material and/or a layer comprising copper and/or cobalt, by
contacting the at least one layer of an aluminium compound at least
once with the composition according to claim 1.
13. The process according to claim 12, wherein the at least one
layer comprising or consisting of an aluminium compound is a top
layer and the layer comprising copper and/or cobalt is a lower
layer covered by the top layer, with or without at least one
further layer being present in between the top layer and the lower
layer.
14. The process according to claim 12, the process comprising a
two-step cleaning process, the process comprising removing in a
first step a metal hard mask, before selectively etching in a
separate second step the at least one layer comprising or
consisting of an aluminium compound.
15. The process according to claim 12, wherein the at least one
layer comprising or consisting of an aluminium compound before
etching has a maximum thickness of 30 nm or below.
Description
[0001] The present invention relates to a composition for
selectively etching a layer comprising an aluminium compound in the
presence of a layer of a low-k material and/or a layer comprising
copper and/or cobalt, and to a corresponding use of said
composition. The present invention further relates to a process for
the manufacture of a semiconductor device, comprising the step of
selectively etching at least one layer comprising an aluminium
compound in the presence of a layer of a low-k material and/or a
layer comprising copper and/or cobalt, by contacting the at least
one layer comprising an aluminium compound with said
composition.
[0002] Processes for manufacturing semiconductor devices are
multiple-step sequences of photolithographic and chemical
processing steps during which electronic circuits are gradually
created on a wafer made of pure semiconducting material (a
"semiconductor wafer"). Preferably, silicon is used as the
semiconductor material. A typical semiconductor wafer is made out
of extremely pure silicon that is grown into mono-crystalline
cylindrical ingots (boules) up to 300 mm in diameter using the
so-called "Czochralski process". These ingots are then sliced into
wafers about 0.75 mm thick and polished to obtain a very regular
and flat surface.
[0003] The particular process for manufacturing semiconductor
wafers is structured in several phases, comprising e.g. the
so-called "front-end-of-line" ("FEOL") and "back-end-of-line"
("BEOL") processing phases.
[0004] The FEOL processing phase refers to the formation of
transistors directly in the material (usually the silicon) of the
semiconductor wafer. The raw semiconductor wafer is engineered by
the growth of an ultrapure, virtually defect-free silicon layer
through epitaxy. Front-end surface engineering is followed by
growth of the gate dielectric (e.g. silicon dioxide), patterning of
the gate, patterning of the source and drain regions, and
subsequent implantation or diffusion of dopants into the
semiconducting material to obtain the desired complementary
electrical properties.
[0005] Once the various devices (e.g. dynamic random access
memories, DRAMs; static random access memories, SRAMs; electrically
programmable read only memories, EPROMs; or complementary metal on
silicon, CMOS) have been created in FEOL processing, they must be
interconnected to form the desired electrical circuits. This occurs
in a series of wafer processing steps collectively referred to as
BEOL. The BEOL processing phase involves creating metal
interconnecting wires on the semiconductor wafer's surface that are
isolated by layers made of material with low dielectric constant,
e.g. a material which has a dielectric constant .eta.<3.9 (also
known as a "low-k material"). With the introduction of copper (Cu)
as electrically conductive material instead of aluminium,
sophisticated multiple-step manufacturing processes for forming
Integrated Circuit (IC) interconnects on semiconductor substrates
have been developed, comprising various methods for selectively
creating and removing consecutive layers of electrically conductive
and of insulating (dielectric) materials, e.g. using chemical
vapour deposition (CVD), electroplating, photolithography, wet
etching or dry etching techniques, chemical-mechanical polishing
(CMP), as well as several cleaning steps, e.g. to remove residues
from previous material removing steps from the surface of a
processed semiconductor substrate. Recently, also cobalt metal has
attracted much interest in the semiconductor industry, e.g. for use
in barrier layers or in seed layers and/or for encapsulating copper
interconnects, to improve processes for manufacturing semiconductor
devices.
[0006] One such multiple-step manufacturing process is known as
damascene manufacturing process with its variants like the dual
damascene process, including the TFVL ("trench-first-via-last")
dual damascene process, the VFTL ("via-first-trench-last") dual
damascene process, the self-aligned dual damascene process or the
dual damascene patterning process with metal hard mask (for the
latter see e.g. document U.S. Pat. No. 6,696,222).
[0007] In the damascene processing technology, the desired IC
interconnect structure is patterned by etching the shape of the
structure into the underlying inter-layer dielectric ("ILD")
materials. After the patterning, typically a thin barrier layer
(e.g. made of Ta/TaN, TiN, CoWP, NiMoP or NiMoB) is deposited on
top of the etched structure as copper diffusion barrier. On top of
that barrier layer a seed layer is often deposited which supports
better adhesion of the copper on the underlying material and acts
as catalytic material during the plating process as well. Typical
materials for these seed layers are compounds which include Pd, Co,
or other compounds, e.g. of polymers and organic materials. The
original deposition process (damascene process) was designed to
process each layer on its own. Hence, the so called "vertical
interconnect accesses" ("vias") and the metallization levels have
different process steps and demand a sequence of cleaning, material
deposition, CMP, and another cleaning step for each layer. A copper
technology using this sequence for its metallization levels as well
as for its ILDs and inter via dielectrics ("IVD"s) is often called
a "single damascene process". Typically, in the single damascene
process each level requires its own cap layer or etch-stop layer, a
separate ILD layer, and at the top there is a need for a
material--for instance SiO.sub.2--that can be polished together
with the interconnect metal copper. Alternatively, the dual
damascene processing technology combines certain similar process
steps to one single process step, thus reducing the number of
process steps and the time and costs required to build the BEOL
stack. Hence the dual damascene process fabricates the IVD and the
metallization layer at once.
[0008] In said damascene manufacturing process or its variants,
electrically conductive masks (or "hard masks") are often used to
protect one or more subjacent layers, e.g. subjacent layers of
dielectric material like of low-k material during certain etch
steps. Such electrically conductive ("metal") masks (or "hard
masks") are usually deposited in the form of a layer comprising
e.g. Ti, TiN,Ta, TaN, Al, HfO.sub.x (i.e. hafnium oxide) or AlCu.
For example, in the dual damascene patterning process with metal
hard mask a metallic layer deposited on the dielectric (low-k)
material serves as hard mask for a second etch step.
[0009] With the ongoing requirement to further minimize the
structures on a semiconductor wafer, manufacturers are facing new
challenges: for example, in integration schemes for further
minimized structures on semiconductor wafers like in integration
schemes for manufacturing 20 nm structures or sub-20 nm structures
or for manufacturing 10 nm structures or sub-10 nm structures on
semiconductor wafers, via creation is preferably done by using a
metal hard mask, often a TiN hard mask, and a subsequent dry etch
step to remove the low-k material which is situated underneath the
metal (e.g. TiN) hard mask (and is optionally separated from the
metal/TiN hardmask by an additional layer, e.g. a non-metal hard
mask or a bonding layer). In order to protect the underlying copper
and/or cobalt at the bottom of the via to be created, a thin
etch-stop layer is usually deposited on the copper and/or cobalt
(i.e. on the copper and/or cobalt metal's surface). This thin
etch-stop layer often comprises or consists of an aluminium
compound and can have a maximum thickness of 30 nm or below, in
particular of 20 nm or below, more in particular of 10 nm or below
or even of 5 nm or below.
[0010] In order to proceed with the manufacturing process, the
following materials have to be removed: 1) the metal (e.g. TiN)
hard mask, 2) any polymeric residues still in the via; and 3) the
etch-stop layer. Simultaneously, materials such as the low-k
material, the copper metal and/or the cobalt metal should not be
etched. This threefold removal of material--while at the same time
preserving to the highest extent possible the layer of low-k
material, the copper metal and/or the cobalt metal--can be achieved
by either a 1-step process or a 2-step process.
[0011] In said 1-step process all of said three removal steps are
performed simultaneously by applying a suitable composition which
usually comprises an oxidation agent like hydrogen peroxide.
[0012] In said 2-step process, in a first step, the metal (e.g.
TiN) hard mask is removed, usually together with residues from
previous production steps, e.g. polymeric residues, by applying a
composition which usually comprises an oxidation agent like
hydrogen peroxide. Said composition should not damage the layer of
low-k material or the etch-stop layer, specifically the etch-stop
layer comprising or consisting of an aluminium compound. In the
second step, the etch-stop layer is to be removed by applying a
suitable composition. Typically, in this second step the polymeric
residues still in the via are also removed (see above).
[0013] The composition to be used in this second step should remove
only the thin etch-stop layer, specifically the etch-stop layer
comprising or consisting of an aluminium compound, and not--or only
to the least possible extent--damage the layer of low-k material,
the copper metal and/or the cobalt metal. For this purpose, the
composition to be used in said second step needs to have properties
which allow a very controlled and specific etching of layers
comprising or consisting of an aluminium compound, even of thin or
ultra-thin layers comprising or consisting of an aluminium
compound, while not compromising layers of low-k materials, copper
metal and/or cobalt metal, which may also be present. The
compositions according to the present invention as defined in this
text are therefore preferably applied in said second step of said
2-step process.
[0014] It has been known that dielectric films of aluminium oxide
can generally be removed by wet etching in acidic and basic media
(see e.g. B. Zhou et al., J. Electrochem. Soc. Vol. 143 (2) 619-623
(1996) or J. Oh et al. J. Electrochem. Soc. Vol. 156 (4) D217-D222
(2011)), however, not with the etch-rate precision and reliability
required for etching thin or ultra-thin etch-stop layers comprising
or consisting of an aluminium compound, e.g. aluminium oxide.
[0015] Document WO 03/035797 relates to an aqueous cleaning
composition containing copper-specific corrosion inhibitor for
cleaning inorganic residues on a semiconductor substrate.
[0016] Document WO 2012/009639 A2 relates to an aqueous cleaner for
the removal of post-etch residues.
[0017] Document US 2004/061092 relates to a wet etch for selective
removal of alumina.
[0018] Document US 2010/0075478 relates to a method for pattern
resist removal.
[0019] Document WO 2009/064336 teaches compositions for removal of
metal hard mask etching residues from a semiconductor
substrate.
[0020] Document WO 2004/030038 A2 relates to compositions substrate
for removing etching residue and use thereof.
[0021] Document US 2012/0052686 relates to a cleaning solution and
damascene processing using the same.
[0022] It was therefore a primary object of the present invention
to provide a composition for selectively etching a layer of an
aluminium compound in the presence of a layer of a low-k material
and/or a layer comprising copper and/or cobalt, with properties
which allow for a very controlled and specific etching, even of
thin or ultra-thin layers of an aluminium compound, while at the
same time not or not significantly compromising layers of low-k
materials and/or layers comprising copper metal and/or cobalt
metal, which are also present.
[0023] It was another specific object of the present invention to
provide a process for manufacturing a semiconductor device wherein
a layer of an aluminium compound is selectively etched in the
presence of a low-k material, of copper metal and/or of cobalt
metal. Further objects of the present invention are disclosed in or
become apparent from the present description and the accompanying
claims.
[0024] It has now been found that the primary object and other
objects of the invention are accomplished by a composition for
selectively etching a layer comprising an aluminium compound,
preferably a layer comprising aluminium oxide, in the presence of a
layer of a low-k material and/or a layer comprising copper and/or
cobalt, the composition comprising (i.e. one or more further
substances may be present): [0025] (A) one or more solubilizers,
selected from the group consisting of [0026] a compound of formula
I:
[0026] ##STR00001## [0027] wherein R.sup.1 is selected from the
group consisting of [0028] hydrogen and [0029] --C(O)--R.sup.2
wherein R.sup.2 is selected from the group consisting of hydrogen
and alkyl having 1, 2, 3 or 4 carbon atoms; [0030] a compound of
formula II:
[0030] ##STR00002## [0031] wherein R.sup.3 is alkyl having 1, 2, 3
or 4 carbon atoms; [0032] trimethylamine-N-oxide, [0033]
triethylamine-N-oxide, [0034] triethanolamine-N-oxide, [0035]
pyridine-N-oxide, [0036] N-ethylpyrrolidine-N-oxide and [0037]
mixtures thereof; [0038] (B) one or more etchants comprising
fluoride anions; preferably selected from the group consisting of
ammonium fluoride, ammonium bifluoride, triethanolammonium
fluoride, diglycolammonium fluoride, methyldiethanolammonium
fluoride, tetramethylammonium fluoride, triethylamine
trihydrofluoride, hydrogen fluoride, fluoroboric acid,
tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic
acid, ammonium fluoroacetate, trifluoroacetic acid, fluorosilicic
acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate
and mixtures thereof; [0039] (C) one or more corrosion inhibitors,
selected from the group consisting of [0040] benzotriazole which is
unsubstituted or substituted once or twice independently by
C.sub.1-4-alkyl, amino-C.sub.1-4-alkyl, phenyl, thiophenyl,
halogen, hydroxy, nitro and/or thiol; [0041] ethylene urea,
ethylene thiourea, 1,2,4-triazole, 5-aminotetrazole,
5-amino-1,3,4-thiadiazol-2-thiol, 3-amino-1H-1,2,4 triazole,
3,5-diamino-1,2,4-triazole, tolyltriazole,
3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole,
1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole,
3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole,
naphthotriazole, 1H-tetrazole-5-acetic acid,
1-phenyl-2-tetrazoline-5-thione, 4-methyl-2-phenylimidazole,
2-mercaptothiazoline, 2 ,4-diamino-6-methyl-1,3,5-triazine,
thiazole, imidazole, benzimidazole, triazine, methyltetrazole,
1,3-dimethyl-2-imidazolidinone, 1,5-pentamethylenetetrazole,
1-phenyl-5-mercaptotetrazole, 2H-imidazole-2-thione,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, tritolyl
phosphate, indazole, adenine, cytosine, guanine, thymine,
2,2'-azanediyldiacetic acid, propanethiol, citric acid, ascorbic
acid, thiourea, 1,1,3,3-tetramethylurea, urea, uric acid, glycine,
dodecylphosphonic acid, oxalic acid, malonic acid, succinic acid,
nitrilotriacetic acid [0042] and mixtures thereof; [0043] (D) one
or more chelating agents selected from the group consisting of
histidine, preferably L-histidine;
1,2-cyclohexylenedinitrilotetraacetic acid,
1,1,1,5,5,5-hexafluoro-2,4-pentanedione, acetylacetonate,
2,2'-azanediyldiacetic acid, ethylenediaminetetraacetic acid,
etidronic acid, methanesulfonic acid, acetylacetone,
1,1,1-trifluoro-2,4-pentanedione, 1,4-benzoquinone,
8-hydroxyquinoline, salicylidene aniline;
tetra-chloro-1,4-benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol,
2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid,
sulfosalicylic acid, salicylic acid, pyridine, 2-ethylpyridine,
2-methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine,
piperidine, piperazine, triethylamine, triethanolamine, ethylamine,
methylamine, isobutylamine, tert-butylamine, tributylamine,
dipropylamine, dimethylamine, diglycol amine, monoethanolamine,
methyldiethanolamine, pyrrole, isoxazole, bipyridine, pyrimidine,
pyrazine, pyridazine, quinoline, isoquinoline, indole, 1
-methylimidazole, diisopropylamine, diisobutylamine, aniline,
pentamethyldiethylenetriamine, acetoacetamide, ammonium carbamate,
ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl
acetoacetate, N-methyl acetoacetamide, tetramethylammonium
thiobenzoate, 2,2,6,6-tetramethyl-3,5-heptanedione,
tetramethylthiuram disulfide, lactic acid, ammonium lactate, formic
acid, propionic acid, gamma-butyrolactone, and mixtures thereof;
and [0044] (G) water.
[0045] It was particularly surprising that the composition
according to the invention is suited to allow for a very controlled
and specific etching of layers comprising or consisting of an
aluminium compound, even of thin or ultra-thin layers comprising or
consisting of an aluminium compound, while at the same time not or
not significantly compromising layers of low-k materials, of copper
metal and/or of cobalt metal which are also present.
[0046] The invention as well as preferred embodiments and preferred
combinations of parameters, properties and elements thereof are
defined in the appended claims. Preferred aspects, details,
modifications and advantages of the present invention are also
defined and explained in the following description and in the
examples stated below.
[0047] In the context of the present invention, an "aluminium
compound" comprises one or more compounds selected from the group
consisting of aluminium oxide ("AlO.sub.x"), aluminium nitride,
aluminium oxynitride ("AlON") and aluminium carbooxynitride
("AlCNO"). Preferably, an aluminium compound also comprises
fluorine. The exact composition of an aluminium compound and the
exact contents or ratios of the elements aluminium, oxygen,
nitrogen, carbon and/or fluorine present in an aluminium compound
as defined herein can vary, e.g. depending on the kind of
pre-treatment of a semiconductor device comprising said aluminium
compound.
[0048] In the context of the present invention, a "layer comprising
or consisting of an aluminium compound" preferably means an
etch-stop layer, more preferably an etch-stop layer deposited on a
copper layer and/or a cobalt layer, preferably on a copper layer or
a cobalt layer.
[0049] An etch-stop layer as referred to herein is--consistent with
the usual meaning in the field--a layer of a material that is not
etched under the conditions applied in usual etching processes for
structuring the surface of a microelectronic device, in particular
a semiconductor wafer, and which covers and thereby protects
subjacent materials which are potentially sensitive to said etching
processes, e.g. copper or other metals like copper interconnects,
from undesired attacks of the etching agents applied. After the
etching process, the etchstop layer can be removed under conditions
specific to the material of the etch-stop layer which removal also
will not negatively affect the subjacent materials.
[0050] In the context of the present invention, a "low-k material"
preferably is a material with a dielectric constant
.eta.<3.9
[0051] and/or (preferably "and")
[0052] is selected from the group consisting of (i)
silicon-containing materials, preferably selected from the group
consisting of SiO.sub.2, silicon oxycarbide (SiOC),
tetraethylorthosilicate (TEOS), boron-doped phosphosilicate glass
(BPSG), fluorine-doped silicon dioxide (fluorosilicate glass, FSG),
carbon-doped silicon dioxide, organo silicate glass (OSG),
carbon-doped oxide (CDO), porous silicon dioxide, porous
carbon-doped silicon-dioxide and spin-on silicon polymeric
materials, preferably hydrogen silsesquioxane (HSQ) and
methylsilsesquioxane (MSQ); preferably organic siloxanes (i.e.
siloxanes comprising carbon-silicon bonds); and preferably organic
silanes (i.e. silanes comprising carbon-silicon bonds) and (ii)
polymeric materials, preferably selected from the group consisting
of spin-on organic polymeric dielectrics, preferably comprising
polyimide (PI); polynorbornenes; benzocyclobutene and
polytetrafluorethylene (PTFE).
[0053] In the context of the present invention, the term
"selectively etching" (or "selective etch rate") preferably means
that upon applying a composition according to the invention to a
layer comprising or consisting of an aluminium compound in the
presence of a layer of a low-k material and/or a layer comprising
copper and/or cobalt, preferably a layer comprising copper, the
etch rate of said composition for etching the layer comprising or
consisting of an aluminium compound, preferably of aluminium oxide,
is at least 10 times, preferably at least 100 times, the etch rate
of said composition for said low-k material and/or for said layer
comprising copper and/or cobalt, preferably for said layer
comprising copper.
[0054] In the context of the present invention, the term
"selectively etching in the presence of a cobalt layer" (or
"selective etch rate in the presence of a cobalt layer" or
equivalent expressions) preferably means that upon applying a
composition according to the invention to a layer comprising or
consisting of an aluminium compound in the presence of a layer of a
low-k material and/or a layer comprising cobalt, the etch rate of
said composition for etching the layer comprising or consisting of
an aluminium compound, preferably of aluminium oxide, is at least 2
times, preferably at least 3 times, the etch rate of said
composition for said low-k material and/or for said layer
comprising cobalt. As is known in the field, cobalt or a layer
comprising cobalt is usually more sensitive to etching processes of
the type described or referred to herein than copper or a layer
comprising copper.
[0055] In the composition according to the invention as defined
above (all variants), the one or more solubilizers (A), the one or
more etchants comprising fluoride anions (B), the one or more
corrosion inhibitors (C) and the one or more chelating agents (D)
generally can in each case be used alone (as one single compound)
or can be used in combination with other compounds of the same type
(solubilizer, etchant, corrosion inhibitor or chelating agent,
respectively, as applicable).
[0056] In component (A), where the one or more solubilizers of the
composition according to the invention comprise a compound of
formula I, R.sup.1 is preferably a group --C(O)--R.sup.2 wherein
R.sup.2 is selected from the group consisting of hydrogen and alkyl
having 1, 2, 3 or 4 carbon atoms. Where R.sup.2 is alkyl having 1,
2, 3 or 4 carbon atoms, this comprises methyl, ethyl and branched
and unbranched propyl and butyl. Preferably, R.sup.2 is hydrogen.
N-formylmorpholine (CAS RN 4394-85-8, also referred to as "NFM" in
this text) is a particularly preferred compound of formula I for
use in the composition according to the invention.
[0057] In component (A) where the one or more solubilizers of the
composition according to the invention comprise a compound of
formula II, R.sup.3 comprises methyl, ethyl and branched and
unbranched propyl and butyl. Preferably, R.sup.3 is methyl.
4-methylmorpholine-4-oxide (also referred to as "4-MM-4-O" in this
text and also known as N-methylmorpholine-N-oxide, CAS RN
7529-22-8) is a particularly preferred compound of formula II for
use in the composition according to the invention. The present
definition of the compound of formula II includes hydrates,
specifically the monohydrate of 4-methylmorpholine-4-oxide (CAS RN
70187-32-5), isomers and tautomers of compounds of formula II.
[0058] In component (B) of the composition according to the
invention (all variants), the one or more etchants comprising
fluoride anions can comprise one or more fluoride anions or provide
one or more fluoride anions upon contact with water. A composition
according to the invention as defined herein (or a composition
according to the invention as described above or below as being
preferred) is thus preferred wherein the or at least one component
(B) is selected from the group consisting of ammonium fluoride,
ammonium bifluoride, ethanolammonium fluoride, diglycolammonium
fluoride, methyldiethanolammonium fluoride, tetramethylammonium
fluoride, triethylamine trihydrofluoride, hydrogen fluoride,
fluoroboric acid, tetrafluoroboric acid, ammonium
tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate,
trifluoroacetic acid, fluorosilicic acid, ammonium fluorosilicate,
tetrabutylammonium tetrafluoroborate and mixtures thereof; and
preferably the or at least one component (B) is ammonium fluoride
(CAS RN 12125-01-8) and wherein component (B) more preferably is
ammonium fluoride.
[0059] Compositions according to the invention comprising ammonium
fluoride as component (B) have shown a stable and reproducible
controlled (selective) etch rate for etching a layer comprising or
consisting of an aluminium compound, in particular of aluminium
oxide, in the presence of a layer of a low-k material and/or a
layer comprising copper and/or cobalt.
[0060] Where component (C) comprises benzotriazole which is
unsubstituted or substituted (as defined above) this definition
comprises one such benzotriazole and a plurality of such
benzotriazoles which can independently be unsusbstituted or
substituted as defined above, and includes mixtures of such
benzotriazoles.
[0061] Where component (C) comprises benzotriazole which is
substituted once or twice independently by C.sub.1-4-alkyl or
amino-C.sub.1-4-alkyl, "C.sub.1-4-alkyl" means alkyl having 1, 2, 3
or 4 carbon atoms and comprises methyl, ethyl and branched and
unbranched propyl and butyl. Where component (C) comprises
benzotriazole which is substituted by C.sub.1-4-alkyl, methyl is
preferred. Specific compounds which are comprised by the present
definition are 5-methylbenzotriazole and 6-methylbenzotriazole (for
applicable nomenclature see below). Where component (C) comprises
benzotriazole which is substituted by amino-C.sub.1-4-alkyl,
2-(5-amino-pentyl) is preferred.
[0062] Where component (C) comprises benzotriazole which is
substituted once or twice independently by halogen, said halogen is
selected from fluorine, chlorine, bromine and iodine. Benzotriazole
substituted by chlorine, preferably substituted once by chlorine,
is preferred. Where component (C) comprises benzotriazole which is
substituted by halogen (preferably as defined here before), this is
also referred to as "halobenzotriazole" in this text.
[0063] Where component (C) comprises benzotriazole which is
unsubstituted or substituted once or twice independently by
C.sub.1-4-alkyl, amino-C.sub.1-4-alkyl, phenyl, thiophenyl,
halogen, hydroxy, nitro and/or thiol this definition specifically
comprises the compounds benzotriazole, 6-methyl-benzotriazole
(6-Me-BTA), 5-methyl-benzotriazole (5-Me-BTA),
1-hydroxybenzotriazole, 5-phenyl-benzotriazole,
5-nitro-benzotriazole, 2-(5-amino-pentyl)-benzotriazole,
5-phenylthiol-benzotriazole, halobenzotriazoles (where halo is
selected from the group consisting of F, Cl, Br and I) and
2-mercaptobenzothiazole.
[0064] As is known in the technical field, in benzotriazoles the
bond between positions (i.e. ring nitrogen atoms) 1 and 2 and the
bond between positions (i.e. ring nitrogen atoms) 2 and 3 have
proved to have the same bond properties. The proton attached to one
nitrogen atom in the nitrogen-containing ring of the benzotriazole
structure does not tightly bind to any of the three ring nitrogen
atoms present but rather migrates rapidly between positions 1 and
3, thus creating tautomers.
[0065] For the purposes of the present invention, the name
"5-methyl-2H-benzotriazole" as used above therefore comprises this
compound and all tautomers thereof, specifically the compounds
known as "5-methyl-benzotriazole", "6-methyl-benzotriazole" (CAS RN
49636-02-4), "6-methyl-1H-benzo[d][1.2.3]triazole",
"5-methyl-1H-benzo[d][1.2.3]triazole" and
"5-methyl-2H-benzo[d][1.2.3]triazole". And vice versa a compound
referred to in the present text as "5-methyl-2H-benzotriazole",
"5-methyl-benzotriazole", "6-methyl-benzotriazole",
"6-methyl-1H-benzo[d][1.2.3]triazole",
"5-methyl-1H-benzo[d][1.2.3]triazole",
"5-methyl-2H-benzo[d][1.2.3]triazole", "5-Me-BTA" or "6-Me-BTA" in
each case has the same meaning as the compound
"5-methyl-2H-benzotriazole and all of its tautomers".
[0066] Correspondingly, for the purposes of the present invention,
the name "5-chloro-2H-benzotriazole" as used in the present text
comprises this compound and all tautomers thereof, specifically the
compounds known as "5-chloro-benzotriazole" (CAS RN 94-97-3),
"6-chloro-benzotriazole", "6-chloro-1H-benzo[d][1.2.3]triazole",
"5-chloro-1H-benzo[d][1.2.3]-triazole" and
"5-chloro-2H-benzo[d][1.2.3]triazole". And vice versa a compound
referred to in the present text as "5-chloro-2H-benzotriazole",
"5-chloro-benzotriazole", "6-chloro-benzotriazole",
"6-chloro-1H-benzo[d][1.2.3]triazole",
"5-chloro-1H-benzo[d][1.2.3]triazole",
"5-chloro-2H-benzo[d][1.2.3]triazole", "5-CI-BTA" or "6-CI-BTA" in
each case has the same meaning as the compound
"5-chloro-2H-benzotriazole and all of its tautomers". This
definition applies mutatis mutandis to other benzotriazoles, in
particular substituted benzotriazoles, as defined or mentioned in
the present text.
[0067] Benzotriazole which is unsubstituted or substituted once or
twice, preferably once, independently by C.sub.1-4-alkyl,
preferably methyl, and/or (preferably "or") halogen is preferred.
In a particularly preferred variant of the present invention,
component (C) is selected from the group consisting of
unsubstituted benzotriazole (BTA), 5-methyl-2H-benzotriazole,
5-chloro-2H-benzotriazole and mixtures thereof.
[0068] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred) is preferred
[0069] wherein [0070] the or at least one component (A) is selected
from the group consisting of [0071] a compound of formula I as
defined above (or a preferred compound of formula I as defined
above), and [0072] a compound of formula II as defined above (ora
preferred compound of formula II as defined above), and/or [0073]
component (B) is selected from the group consisting of ammonium
fluoride, ammonium bifluoride, triethanolammonium fluoride,
diglycolammonium fluoride, methyldiethanol-ammonium fluoride,
tetramethylammonium fluoride, triethylamine trihydrofluoride,
hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid,
ammonium tetrafluoroborate, fluoroacetic acid, ammonium
fluoroacetate, trifluoroacetic acid, fluorosilicic acid, ammonium
fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures
thereof; [0074] and preferably the or at least one component (B) is
ammonium fluoride and more preferably component (B) is ammonium
fluoride, and/or [0075] the or at least one component (C) is
selected from the group consisting of [0076] benzotriazole which is
unsubstituted or substituted once or twice, preferably once,
independently by C.sub.1-4-alkyl, amino-C.sub.1-4-alkyl, phenyl;
thiophenyl; halogen, hydroxy, nitro and/or (preferably "or") thiol;
[0077] preferably benzotriazole which is unsubstituted or
substituted once or twice, preferably once, independently by
C.sub.1-4-alkyl and/or (preferably "or") halogen, [0078] succinic
acid and [0079] mixtures thereof.
[0080] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred) is also preferred
[0081] wherein [0082] the or at least one component (D) is selected
from the group consisting of histidine, preferably L-histidine;
1,2-cyclohexylenedinitrilotetraacetic acid, and mixtures thereof,
and/or [0083] the composition comprises as further component:
[0084] (E) one or more surfactants.
[0085] In the compositions according to the invention as defined
above, the one or more surfactants (E) generally (if present) can
in each case be used alone (as one single compound) or can be used
in combination with other compounds of the same type.
[0086] Further preferred is a composition according to the
invention as defined herein (or a composition according to the
invention as described above or below as being preferred)
[0087] wherein [0088] the pH of the composition is in the range of
from 3.5 to 8, and/or [0089] the composition comprises as further
component: [0090] (F) a buffering system which is suitable to
buffer the pH of the composition in the range of from 3.5 to 8.
[0091] Also preferred is a composition according to the invention
as defined herein (or a composition according to the invention as
described above or below as being preferred) comprising (i.e. one
or more further substances may be present): [0092] (A) one or more
solubilizers selected from the group consisting of [0093] a
compound of formula I as defined above (or a preferred compound of
formula I as defined above), [0094] and [0095] a compound of
formula II as defined above (ora preferred compound of formula II
as defined above), [0096] (B) one or more etchants, selected from
the group consisting of ammonium fluoride, ammonium bifluoride,
triethanolammonium fluoride, diglycolammonium fluoride,
methyldiethanolammonium fluoride, tetramethylammonium fluoride,
triethylamine trihydrofluoride, hydrogen fluoride, fluoroboric
acid, tetrafluoroboric acid, ammonium tetrafluoroborate,
fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid,
fluorosilicic acid, ammonium fluorosilicate, tetrabutylammonium
tetrafluoroborate and mixtures thereof; [0097] wherein preferably
the or at least one etchant component (B) is ammonium fluoride and
more preferably etchant component (B) is ammonium fluoride; [0098]
(C) one or more corrosion inhibitors, selected from the group
consisting of [0099] benzotriazole which is unsubstituted or
substituted once or twice, preferably once, independently by
C.sub.1-4-alkyl, amino-C.sub.1-4-alkyl, phenyl, thiophenyl,
halogen, hydroxy, nitro and/or (preferably "or") thiol; [0100]
preferably benzotriazole which is unsubstituted or substituted once
or twice, preferably once, independently by C.sub.1-4-alkyl and/or
(preferably "or") halogen, [0101] succinic acid [0102] and [0103]
mixtures thereof, [0104] (D) one or more chelating agents selected
from the group consisting of histidine,
1,2-cyclohexylenedinitrilotetraacetic acid and mixtures thereof and
[0105] (G) water,
[0106] wherein the pH of the composition is in the range of from
3.5 to 8.
[0107] In a first preferred variant, the composition according to
the present invention pertains to a composition for selectively
etching a layer comprising an aluminium compound, preferably a
layer comprising aluminium oxide, in the presence of a layer of a
low-k material and/or a layer comprising copper and/or cobalt,
preferably in the presence of a low-k material and/or a copper
layer, the composition comprising (i.e. one or more further
substances may be present) or consisting of (i.e. no further
substances are present in addition to component (A) to (G) as
defined hereinafter) [0108] (A) one or more solubilizers, selected
from the group consisting of 4-methylmorpholine-4-oxide,
trimethylamine-N-oxide, triethylamine-N-oxide,
triethanolamine-N-oxide, pyridine-N-oxide,
N-ethylmorpholine-N-oxide, N-ethylpyrrolidine-N-oxide and mixtures
thereof; [0109] (B) one or more etchants comprising fluoride
anions, preferably selected from the group consisting of ammonium
fluoride, ammonium bifluoride, triethanolammonium fluoride,
diglycolammonium fluoride, methyldiethanolammonium fluoride,
tetramethylammonium fluoride, triethylamine trihydrofluoride,
hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid,
ammonium tetrafluoroborate, fluoroacetic acid, ammonium
fluoroacetate, trifluoroacetic acid, fluorosilicic acid, ammonium
fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures
thereof; [0110] (C) one or more corrosion inhibitors, selected from
the group consisting of benzotriazole, (6-methyl-benzotriazole
(6-Me-BTA)), 5-methyl-benzotriazole, ethylene urea, ethylene
thiourea, 1,2,4-triazole, 5-aminotetrazole, 1-hydroxybenzotriazole,
5-amino-1,3,4-thiadiazol-2-thiol, 3-amino-1H-1,2,4 triazole,
3,5-diamino-1,2,4-triazole, tolyltriazole, 5-phenyl-benzotriazole,
5-nitro-benzotriazole, 3-amino-5-mercapto-1,2,4-triazole, 1
-amino-1,2,4-triazole, 2-(5-amino-pentyl)-benzotriazole,
1-amino-1,2,3-triazole, 1 -amino-5-methyl-1,2,3-triazole,
3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole,
5-phenylthiol-benzotriazole, halobenzotriazoles (where halo is
selected from the group consisting of F, Cl, Br and I),
naphthotriazole, 1 H-tetrazole-5-acetic acid,
2-mercaptobenzothiazole, 1-phenyl-2-tetrazoline-5-thione,
2-mercaptobenzimidazole, 4-methyl-2-phenylimidazole,
2-mercaptothiazoline, 2,4-diamino-6-methyl-1,3,5-triazine,
thiazole, imidazole, benzimidazole, triazine, methyltetrazole,
1,3-di-methyl-2-imidazolidinone, 1,5-pentamethylenetetrazole,
1-phenyl-5-mercapto-tetrazole, 2H-imidazole-2-thione,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, tritolyl
phosphate, indazole, adenine, cytosine, guanine, thymine,
2,2'-azanediyldiacetic acid, propanethiol, citric acid, ascorbic
acid, thiourea, 1,1,3,3-tetramethylurea, urea, uric acid, glycine,
dodecylphosphonic acid, oxalic acid, malonic acid, succinic acid,
nitrilotriacetic acid and mixtures thereof; [0111] (D) one or more
chelating agents selected from the group consisting of
1,2-cyclohexylenedinitrilotetraacetic acid,
1,1,1,5,5,5-hexafluoro-2,4-pentanedione, acetylacetonate,
2,2'-azanediyldiacetic acid, ethylenediaminetetraacetic acid,
etidronic acid, methanesulfonic acid, acetylacetone,
1,1,1-trifluoro-2,4-pentanedione, 1,4-benzoquinone,
8-hydroxyquinoline, salicylidene aniline;
tetrachloro-1,4-benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol,
2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid,
sulfosalicylic acid, salicylic acid, pyridine, 2-ethylpyridine,
2-methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine,
piperidine, piperazine, triethylamine, triethanolamine, ethylamine,
methylamine, isobutylamine, tert-butylamine, tributylamine,
dipropylamine, dimethylamine, diglycol amine, monoethanolamine,
methyldiethanolamine, pyrrole, isoxazole, bipyridine, pyrimidine,
pyrazine, pyridazine, quinoline, isoquinoline, indole, 1
-methylimidazole, diisopropylamine, diisobutylamine, aniline,
pentamethyldiethylenetriamine, acetoacetamide, ammonium carbamate,
ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl
acetoacetate, N-methyl acetoacetamide, tetramethylammonium
thiobenzoate, 2,2,6,6-tetramethyl-3,5-heptanedione,
tetramethylthiuram disulfide, lactic acid, ammonium lactate, formic
acid, propionic acid, gamma-butyrolactone,and mixtures thereof;
[0112] (E) one or more surfactants; [0113] (F) a buffering system
which is suitable to buffer the pH of the composition in the range
of from 6 to 8, preferably in the range of from 6.4 to 7.5, and
[0114] (G) water,
[0115] wherein the pH of the composition is in the range of from 6
to 8, preferably in the range of from 6.4 to 7.5.
[0116] In the compositions according to the invention as defined
above, specifically in the composition according to the invention
according to the first preferred variant, the one or more
solubilizers (A), the one or more etchants comprising fluoride
anions (B), the one or more corrosion inhibitors (C), the one or
more chelating agents (D) and the one or more surfactants (E)
generally can in each case be used alone (as one single compound)
or can be used in combination with other compounds of the same type
(solubilizer, etchant, corrosion inhibitor, chelating agent or
surfactant, respectively, as applicable).
[0117] Preferred is a composition according to the first preferred
variant of the invention as defined herein, wherein
[0118] the buffering system (F) is selected from the group
consisting of a phosphate buffer comprising NaH.sub.2PO.sub.4 and
Na.sub.2HPO.sub.4, a HEPES buffer comprising
2-[4-(2-hydroxyethyl)piper-azin-1-yl]ethanesulfonic acid, a TRIS
buffer comprising tris(hydroxymethyl)-amino-methane, an ammonium
acetate buffer and mixtures thereof, [0119] more preferably the
buffering system is or comprises an ammonium acetate buffer and
most preferably is an ammonium acetate buffer, and/or [0120] the pH
of the composition is in the range of from 6.4 to 7.5, preferably
in the range of from 6.8 to 7.5, more preferably in the range of
from 7.0 to 7.4.
[0121] In the above-defined preferred composition according to the
first preferred variant of the invention, the use of a single
buffering system (e.g. just an ammonium acetate buffer or just a
HEPES buffer) is preferred over the use of a mixture of buffering
systems. All of said buffers as defined here above are known in the
art and a skilled person will be aware how to apply and adjust said
buffers in the context of the present invention. Compositions
according to the invention with a pH in the range of from 6.4 to
7.5, preferably in the range of from 6.8 to 7.5, more preferably in
the range of from 7.0 to 7.4 have shown a particularly stable and
reproducible controlled (selective) etch rate for etching a layer
comprising or consisting of an aluminium compound, preferably of
aluminium oxide, in the presence of a layer of a low-k material
and/or a layer comprising copper and/or cobalt, preferably in the
presence of a low-k material and/or a copper layer. In addition,
the aforementioned compositions according to the invention have
shown to be particularly stable, e.g. storage-stable over a period
of 6 months.
[0122] A composition according to the first preferred variant of
the invention as defined herein (or a composition according to the
first preferred variant of the invention as described above or
below as being preferred) is preferred wherein the or at least one
component (A) is 4-methylmorpholine-4-oxide (CAS RN 7529-22-8) and
wherein preferably component (A) is 4-methylmorpholine-4-oxide.
[0123] Compositions according to the first preferred variant of the
invention comprising 4-methyl-morpholine-4-oxide as component (A)
have shown a stable and reproducible selective etch rate for
etching a layer comprising or consisting of an aluminium compound,
in particular of aluminium oxide, in the presence of a layer of a
low-k material and/or a layer comprising copper and/or cobalt, in
particular in the presence of a layer of a low-k material and/or a
copper layer.
[0124] Compositions according to the first preferred variant of the
invention comprising ammonium fluoride as component (B) have shown
a stable and reproducible controlled (selective) etch rate for
etching a layer comprising or consisting of an aluminium compound,
in particular of aluminium oxide, in the presence of a layer of a
low-k material and/or a layer comprising copper and/or cobalt, in
particular in the presence of a layer of a low-k material and/or a
copper layer.
[0125] A composition according to the first preferred variant of
the invention as defined herein (or a composition according to the
first preferred variant of the invention as described above or
below as being preferred) is also preferred wherein component (C)
is selected from the group consisting of benzotriazole (CAS RN
95-14-7), 6-methyl-benzotriazole (CAS RN 136-85-6) and a
combination (i.e. a mixture) of benzotriazole and
6-methyl-benzotriazole, and preferably component (C) is a
combination of benzotriazole and 6-methyl-benzotriazole.
Compositions according to the first preferred variant of the
invention comprising benzotriazole, 6-methyl-benzotriazole and a
combination of benzotriazole and 6-methyl-benzotriazole as
component (C), preferably comprising a combination of benzotriazole
and 6-methyl-benzotriazole as component (C), have shown to be
associated with a preferred particularly low copper etch rate. For
nomenclature of unsubstituted and substituted benzotriazoles also
see above.
[0126] A composition according to the first preferred variant of
the invention as defined herein (or a composition according to the
first preferred variant of the invention as described above or
below as being preferred) is also preferred wherein component (D)
is 1,2-cyclohexylene-dinitrilotetraacetic acid (CDTA; CAS RN
13291-61-7) or comprises CDTA as well as one or more of the other
chelating agents above. Compositions according to the first
preferred variant of the invention comprising CDTA as component (D)
have shown a stable and reproducible controlled (selective) etch
rate for etching a layer comprising or consisting of an aluminium
compound,in particular of aluminium oxide, in the presence of a
layer of a low-k material and/or a layer comprising copper and/or
cobalt, in particular in the presence of a layer of a low-k
material and/or a copper layer: said etch rate on semiconductor
wafers was found to be uniform over a single wafer, with few or no
centre-edge effects, and between different wafers.
[0127] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred), in particular a composition according to
the first preferred variant of the invention as defined herein, is
also preferred wherein the one or more surfactants (E) (if present)
are selected from the group consisting of:
[0128] (i) anionic surfactants, preferably selected from the group
consisting of ammonium lauryl sulfate, fluorosurfactants,
preferably selected from the group consisting of perfluorinated
alkylsulfonamide salts (preferably perfluorinated, N-substituted
alkylsulfonamide ammonium salts, PNAAS), perfluorooctanesulfonate,
perfluorobutanesulfonate, perfluorononanoate and
perfluorooctanoate; alkyl-aryl ether phosphates and alkyl ether
phosphates,
[0129] (ii) zwitterionic surfactants, preferably selected from the
group consisting of
(3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate)
("CHAPS"), cocamidopropyl hydroxy-sultaine (CAS RN 68139-30-0),
{[3-(dodecanoylamino)propyl](dimethyl)ammonio}acetate,
phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine
and
[0130] (iii) non-ionic surfactants, preferably selected from the
group consisting of glucoside alkyl ethers, glycerol alkyl ethers,
cocamide ethanolamines and lauryldimethylaminoxide.
[0131] More preferred surfactants (E) in compositions according to
the first preferred variant of the invention are or comprise
perfluorinated, N-substituted alkylsulfonamide ammonium salts.
[0132] Preferred surfactants (E) in compositions according to the
invention do not comprise metals or metal ions.
[0133] In individual cases, a composition according to the first
preferred variant of the invention as defined herein (or a
composition according to the first preferred variant of the
invention as described above or below as being preferred) can
further comprise as an optional additional component: [0134] (H)
one or more water-miscible organic solvents, preferably selected
from the group consisting of tetrahydrofuran (THF),
N-methylpyrrolidone (NMP), dimethyl formamide (DMF), dimethyl
sulfoxide (DMSO), ethanol, isopropanol, butyldiglycol, butylglycol,
sulfolane (2,3,4,5-tetrahydrothiophene-1,1-dioxide) and mixtures
thereof; more preferably selected from the group consisting of THF,
NMP, DMF, DMSO, sulfolane and mixtures thereof.
[0135] The term "water-miscible organic solvent" in the context of
the present invention preferably means that an organic solvent
fulfilling this requirement is miscible with water at least in a
1:1 (w/w) ratio at 20.degree. C. and ambient (atmospheric)
pressure. Preferably the or at least one water-miscible organic
solvent (H) is sulfolane. More preferred are compositions according
to the first preferred variant of the present invention which do
not comprise one or more water-miscible organic solvents (H).
[0136] A composition according to the first preferred variant of
the invention as defined herein is particularly preferred wherein
one or more or all of the components (A), (B), (C), (D), (E) and
(F) as defined above as being preferred are combined to result in a
final (ready-to-use) composition according to the first preferred
variant of the invention (comprising all components (A) to (G) or,
in the less preferred case where component (H) is present, all
components (A) to (H)).
[0137] In a second preferred variant, the composition according to
the present invention pertains to a composition for selectively
etching a layer comprising an aluminium compound, preferably a
layer comprising aluminium oxide, in the presence of a layer of a
low-k material and/or a layer comprising copper and/or cobalt,
preferably in the presence of a low-k material and/or a cobalt
layer, the composition comprising (i.e. one or more further
substances may be present) or consisting of (i.e. no further
substances are present in addition to component (A) to (D) and (G)
as defined hereinafter): [0138] (A) one or more solubilizers,
selected from the group consisting of [0139] a compound of formula
I (with the preferred meanings of substituents R.sup.1 and R.sup.2
as defined above):
[0139] ##STR00003## [0140] wherein R.sup.1 is selected from the
group consisting of [0141] hydrogen and [0142] --C(O)--R.sup.2
wherein R.sup.2 is selected from the group consisting of hydrogen
and alkyl having 1, 2, 3 or 4 carbon atoms; [0143] a compound of
formula II (with the preferred meanings of substituent R.sup.3 as
defined above):
[0143] ##STR00004## [0144] wherein R.sup.3 is alkyl having 1, 2, 3
or 4 carbon atoms; [0145] trimethylamine-N-oxide [0146]
triethylamine-N-oxide, [0147] triethanolamine-N-oxide, [0148]
pyridine-N-oxide, [0149] N-ethylpyrrolidine-N-oxide and [0150]
mixtures thereof; [0151] (B) one or more etchants comprising
fluoride anions, preferably selected from the group consisting of
ammonium fluoride, ammonium bifluoride, triethanolammonium ride,
diglycolammonium fluoride, methyldiethanolammonium fluoride,
tetramethylammonium fluoride, triethylamine trihydrofluoride,
hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid,
ammonium tetrafluoroborate, fluoroacetic acid, ammonium
fluoroacetate, trifluoroacetic acid, fluorosilicic acid, ammonium
fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures
thereof; [0152] (C) one or more corrosion inhibitors, selected from
the group consisting of [0153] benzotriazole which is unsubstituted
or substituted once or twice independently by C.sub.1-4-alkyl,
amino-C.sub.1-4-alkyl, phenyl, thiophenyl, halogen, hydroxy, nitro
and/or thiol; [0154] ethylene urea, ethylene thiourea,
1,2,4-triazole, 5-aminotetrazole, 5-amino-1,3,4-thiadiazol-2-thiol,
3-amino-1H-1,2,4 triazole, 3,5-diamino-1,2,4-triazole,
tolyltriazole, 3-amino-5-mercapto-1,2,4-triazole, 1
-amino-1,2,4-triazole, 2-(5-amino-pentyl)-benzotriazole, 1
-amino-1,2,3-triazole, 1 -amino-5-methyl-1,2,3-triazole,
3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole,
naphthotriazole, 1 H-tetrazole-5-acetic acid,
1-phenyl-2-tetrazoline-5-thione, 4-methyl-2-phenylimidazole,
2-mercaptothiazoline, 2,4-diamino-6-methyl-1,3,5-triazine,
thiazole, imidazole, benzimidazole, triazine, methyltetrazole,
1,3-dimethyl-2-imidazolidinone, 1,5-pentamethylenetetrazole,
1-phenyl-5-mercaptotetrazole, 2H-imidazole-2-thione,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, tritolyl
phosphate, indazole, adenine, cytosine, guanine, thymine,
2,2'-azanediyldiacetic acid, propanethiol, citric acid, ascorbic
acid, thiourea, 1,1,3,3-tetramethylurea, urea, uric acid, glycine,
do-decylphosphonic acid, oxalic acid, malonic acid, succinic acid,
nitrilotriacetic acid [0155] and mixtures thereof; [0156] (D) one
or more chelating agents selected from the group consisting of
histidine, preferably
L-histidine;1,2-cyclohexylenedinitrilotetraacetic acid,
1,1,1,5,5,5-hexafluoro-2,4-pentanedione, acetylacetonate,
2,2'-azanediyldiacetic acid, ethylenediaminetet-raacetic acid,
etidronic acid, methanesulfonic acid, acetylacetone,
1,1,1-trifluoro-2,4-pentanedione, 1,4-benzoquinone,
8-hydroxyquinoline, salicylidene aniline;
tetra-chloro-1,4-benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol,
2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid,
sulfosalicylic acid, salicylic acid, pyridine, 2-ethylpyridine,
2-methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine,
piperidine, piperazine, triethylamine, triethanolamine, ethylamine,
methylamine, isobutylamine, tert-butylamine, tributylamine,
dipropylamine, dimethylamine, diglycol amine, monoethanolamine,
methyldiethanolamine, pyrrole, isoxazole, bipyridine, pyrimidine,
pyrazine, pyridazine, quinoline, isoquinoline, indole, 1
-methylimidazole, diisopropylamine, diisobutylamine, aniline,
pentamethyldiethylenetriamine, acetoacetamide, ammonium carbamate,
ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl
acetoacetate, N-methyl acetoacetamide, tetramethylammonium
thiobenzoate, 2,2,6,6-tetramethyl-3,5-heptanedione,
tetramethyl-thiuram disulfide, lactic acid, ammonium lactate,
formic acid, propionic acid, gamma-butyrolactone, and mixtures
thereof; and [0157] (G) water,
[0158] wherein preferably the pH of the composition is in the range
of from 3.5 to 6, preferably in the range of from 4.0 to 5.5.
[0159] In the compositions according to the invention as defined
above, specifically in the composition according to the second
preferred variant of the invention, the one or more solubilizers
(A), the one or more etchants comprising fluoride anions (B), the
one or more corrosion inhibitors (C) and the one or more chelating
agents (D) generally can in each case be used alone (as one single
compound) or can be used in combination with other compounds of the
same type (solubilizer, etchant, corrosion inhibitor or chelating
agent, respectively, as applicable).
[0160] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred, including compositions of the first
preferred variant and the second preferred variant) is also
preferred wherein the total amount of the one or more solubilizers
of component (i.e. the solubilizer component, preferably the
preferred solubilizer components as defined above) (A) present is
in the range of from 0.01 to 20 wt.-%, preferably in the range of
from 2 to 15 wt.-%, more preferably in the range of from 2 to 12
wt.-%; and in some cases preferably in the range of from 2 to 6
wt.-%, based on the total weight of the composition.
[0161] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred, including compositions of the first
preferred variant and the second preferred variant) is also
preferred wherein the total amount of the one or more etchants of
component (B) (comprising fluoride anions, i.e. the etchant
component, preferably the preferred etchants of component (B) as
defined above) present is in the range of from 0.001 to 1 wt.-%,
preferably in the range of from 0.01 to 0.1 wt.-%, more preferably
in the range of from 0.02 to 0.08 wt.-%, based on the total weight
of the composition. Compositions according to the invention
comprising the etchant component (B) in the here defined preferred
total amounts have shown a superior balance of acceptable etch
rate, in particular for etching a layer comprising or consisting of
an aluminium compound, preferably of aluminium oxide, and etch rate
selectivity, in particular in the presence of a layer of a low-k
material and/or a layer comprising copper and/or cobalt, more in
particular a copper layer where a composition according to the
first preferred variant of the invention is concerned and more in
particular a cobalt layer, where a composition according to the
second preferred variant of the invention is concerned.
[0162] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred, including compositions of the first
preferred variant and the second preferred variant) is also
preferred wherein the total amount of the one or more corrosion
inhibitors (i.e. the corrosion inhibitor component, preferably the
preferred corrosion inhibitor components as defined above) (C)
present is in the range of from 0.01 to 4 wt.-%, preferably in the
range of from 0.1 to 2 wt.-%, more preferably in the range of from
0.2 to 1.5 wt.-%, based on the total weight of the composition.
Compositions according to the invention comprising the corrosion
inhibitor component (C) in the here defined preferred total amounts
have shown a superior balance of acceptable etch rate, in
particular for etching a layer comprising or consisting of an
aluminium compound, preferably of aluminium oxide, and etch rate
selectivity, in particular in the presence of a layer of a low-k
material and/or a layer comprising copper and/or cobalt layer, more
in particular a copper layer where a composition according to the
first preferred variant of the invention is concerned and more in
particular a cobalt layer (i.e. a selective etch rate in the
presence of a cobalt layer), where a composition according to the
second preferred variant of the invention is concerned.
[0163] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred, including compositions of the first
preferred variant and the second preferred variant) is also
preferred wherein the total amount of the one or more chelating
agents of component (i.e. the chelating agent component, preferably
the preferred chelating agent components as defined above) (D)
present is in the range of from 0.01 to 4 wt.-%, preferably in the
range of from 0.02 to 1 wt.-%, more preferably in the range of from
0.05 to 0.8 wt.-%, based on the total weight of the
composition.
[0164] A composition according to the invention as defined herein,
preferably a composition according to the first preferred variant
(or a composition according to the invention, preferably according
to the first preferred variant, as described above or below as
being preferred) is also preferred wherein the total amount of the
one or more surfactants of component (i.e. the surfactant
component, preferably the preferred surfactant components as
defined above) (E) present is in the range of from 0.0001 to 1
wt.-%, preferably in the range of from 0.001 to 0.5 wt.-%, more
preferably in a total amount in the range of from 0.002 to 0.1
wt.-%, based on the total weight of the composition.
[0165] A composition according to the invention as defined herein,
preferably a composition of the first preferred variant (or a
composition according to the invention, preferably according to the
first preferred variant, as described above or below as being
preferred) is also preferred wherein the total amount of buffering
system of component (i.e. the buffer component) (F) present is in
the range of from 0.1 to 10 wt.-%, preferably in the range of from
0.2 to 5 wt.-%, more preferably in the range of from 0.3 to 3
wt.-%, based on the total weight of the composition.
[0166] In individual cases, a composition according to the first
preferred variant of the invention as defined herein (or a
composition according to the first preferred variant of the
invention as described above or below as being preferred) is
preferred wherein the total amount of the one or more
water-miscible organic solvents, (i.e. the solvent component) (H)
present is in the range of from 0 to 30 wt.-%, preferably in the
range of from 0 to 10 wt.-%, more preferably in the range of from 0
to 7.5 wt.-%, even more preferably in the range of from 0 to 6
wt.-%, based on the total weight of the composition.
[0167] A composition according to the invention as defined herein
(or a composition according to the invention as described above or
below as being preferred, including compositions of the first
preferred variant and the second preferred variant) is also
preferred wherein the amounts of components (A), (B), (C), (D), (E)
(if present), (F) (if present), (G) and (H) (if present) add to a
total of 100 wt.-% (i.e. the total weight) of the composition,
where preferably water is the balance to a total of 100 wt.-% (i.e.
the total weight) of the composition.
[0168] A composition according to the first preferred variant of
the invention as defined herein is particularly preferred wherein
the above-defined total amounts or preferred total amounts of
components (A), (B), (C), (D), (E), (F) and (optionally) (H) are
combined with the preferred or more preferred components (A), (B),
(C), (D), (E), (F) and/or (optionally) (H), as defined above.
[0169] A composition according to the first preferred variant of
the invention as defined herein (or a composition according to the
first preferred variant of the invention as described above or
below as being preferred) is particularly preferred wherein the
composition consists of (i.e. no further substances are present in
addition to component (A) to (H) as defined hereinafter) [0170] (A)
one or more solubilizers, selected from the group consisting of
4-methylmorpholine-4-oxide, trimethylamine-N-oxide,
triethylamine-N-oxide, triethanolamine-N-oxide; pyridine-N-oxide,
N-ethylmorpholine-N-oxide, N-ethylpyrrolidine-N-oxide and mixtures
thereof, and preferably the one or more solubilizers is or
comprises 4-methyl-morpholine-4-oxide, [0171] in a total amount in
the range of from 0.01 to 20 wt.-%, preferably in the range of from
2 to 12 wt.-%, more preferably in the range of from 2 to 6 wt.-%,
preferably of 4-methylmorpholine-4-oxide, based on the total weight
of the composition; [0172] (B) one or more etchants comprising
fluoride anions, selected from the group consisting of ammonium
fluoride, ammonium bifluoride, triethanolammonium fluoride,
di-glycolammonium fluoride, methyldiethanolammonium fluoride,
tetramethylammonium fluoride, triethylamine trihydrofluoride,
hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid,
ammonium tetrafluoroborate, fluoroacetic acid, ammonium
fluoro-acetate, trifluoroacetic acid, fluorosilicic acid, ammonium
fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures
thereof, and preferably is or comprises ammonium fluoride, [0173]
in a total amount in the range of from 0.01 to 0.1 wt.-%, more
preferably in a total amount in the range of from 0.02 to 0.08
wt.-%, preferably of ammonium fluoride, based on the total weight
of the composition; [0174] (C) one or more corrosion inhibitors,
selected from the group consisting of benzotriazole,
6-methyl-benzotriazole, 5-methyl-benzotriazole, ethylene urea,
ethylene thiourea, 1,2,4-triazole, 5-aminotetrazole,
1-hydroxybenzotriazole, 5-amino-1,3,4-thiadiazol-2-thiol,
3-amino-1H-1,2,4 triazole, 3,5-diamino-1,2,4-triazole,
tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole,
3-amino-5-mercapto-1,2,4-triazole, 1 -amino-1,2,4-triazole,
2-(5-amino-pentyl)-benzotriazole, 1 -amino-1,2,3-triazole, 1
-amino-5-methyl-1,2,3-triazole, 3-mercapto-1,2,4-triazole,
3-isopropyl-1,2,4-triazole, 5-phenyl-thiol-benzotriazole,
halobenzotriazoles (where halo is selected from the group
consisting of F, Cl, Br and I), naphthotriazole, 1
H-tetrazole-5-acetic acid, 2-mercapto-benzothiazole,
1-phenyl-2-tetrazoline-5-thione, 2-mercaptobenzimidazole,
4-methyl-2-phenylimidazole, 2-mercaptothiazoline,
2,4-diamino-6-methyl-1,3,5-triazine, thiazole, imidazole,
benzimidazole, triazine, methyltetrazole,
1,3-dimethyl-2-imidazolidinone, 1,5-pentamethylenetetrazole,
1-phenyl-5-mercaptotetrazole, 2H-imidazole-2-thione,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, tritolyl
phosphate, indazole, adenine, cytosine, guanine, thymine,
2,2'-azanediyldiacetic acid, propanethiol, citric acid, ascorbic
acid, thiourea, 1,1,3,3 -tetramethylurea, urea, uric acid, glycine,
dodecylphosphonic acid, oxalic acid, malonic acid, succinic acid,
nitrilotriacetic acid and mixtures thereof, and preferably is
selected from the group consisting of benzotriazole,
6-methyl-benzotriazole and mixtures thereof, [0175] in a total
amount in the range of from 0.01 to 4 wt.-%, preferably in a total
amount in the range of from 0.1 to 2 wt.-%, more preferably in a
total amount in the range of from 0.2 to 1.5 wt.-%, preferably
selected from the group consisting of benzotriazole,
6-methyl-benzotriazole and mixtures thereof, based on the total
weight of the composition; [0176] (D) one or more chelating agents
selected from the group consisting of
1,2-cyclo-hexylenedinitrilotetraacetic acid,
1,1,1,5,5,5-hexafluoro-2,4-pentanedione, acetylacetonate,
2,2'-azanediyldiacetic acid, ethylenediaminetetraacetic acid,
etidronic acid, methanesulfonic acid, acetylacetone,
1,1,1-trifluoro-2,4-pentanedione, 1,4-benzoquinone,
8-hydroxyquinoline, salicylidene aniline;
tetrachloro-1,4-benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol,
2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid,
sulfosalicylic acid, salicylic acid, pyridine, 2-ethylpyridine,
2-methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine,
piperidine, piperazine, triethylamine, triethanolamine, ethylamine,
methylamine, isobutylamine, tert-butylamine, tributylamine,
dipropylamine, dimethylamine, diglycol amine, monoethanolamine,
methyldiethanolamine, pyrrole, isoxazole, bipyridine, pyrimidine,
pyrazine, pyridazine, quinoline, isoquinoline, indole, 1
-methylimidazole, diisopropylamine, diisobutylamine, aniline,
pentamethyldiethylenetriamine, acetoacetamide, ammonium carbamate,
ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl
acetoacetate, N-methyl acetoacetamide, tetramethylammonium
thiobenzoate, 2,2,6,6-tetramethyl-3,5-heptanedione,
tetramethylthiuram disulfide, lactic acid, ammonium lactate, formic
acid, propionic acid, gamma-butyrolactone, and mixtures thereof,
and preferably is or comprises
1,2-cyclohexylenedinitrilo-tetraacetic acid, [0177] in a total
amount in the range of from 0.01 to 4 wt.-%, preferably in a total
amount in the range of from 0.02 to 1 wt.-%, more preferably in a
total amount in the range of from 0.05 to 0.8 wt.-%, preferably of
1,2-cyclohexylenedinitrilotetraacetic acid, based on the total
weight of the composition; [0178] (E) one or more surfactants
selected from the group consisting of (i) anionic surfactants,
preferably selected from the group consisting of ammonium lauryl
sulfate, fluorosur-factants, preferably selected from the group
consisting of perfluorinated alkylsulfon-amide salts (preferably
perfluorinated, N-substituted alkylsulfonamide ammonium salts),
perfluorooctanesulfonate, perfluorobutanesulfonate,
perfluorononanoate and perfluorooctanoate; alkyl-aryl ether
phosphates and alkyl ether phosphates, (ii) zwit-terionic
surfactants, preferably selected from the group consisting of
(3-[(3-chol-amidopropyl)dimethylammonio]-1-propanesulfonate),
cocamidopropyl hydroxysul-taine,
{[3-(dodecanoylamino)propyl](dimethyl)ammonio}acetate,
phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine,
(iii) non-ionic surfactants, preferably selected from the group
consisting of glucoside alkyl ethers, glycerol alkyl ethers,
cocamide ethanolamines and lauryldimethylaminoxide; and preferably
the one or more surfactants are or comprise perfluorinated,
N-substituted alkylsulfonamide ammonium salts, [0179] in a total
amount in the range of from 0.0001 to 1 wt.-%, preferably in a
total amount in the range of from 0.001 to 0.5 wt.-%, more
preferably in a total amount in the range of from 0.002 to 0.1
wt.-%, preferably selected from the group consisting of
perfluorinated, N-substituted alkylsulfonamide ammonium salts,
based on the total weight of the composition; [0180] (F) a
buffering system which is suitable to buffer the pH of the
composition in the range of from 6.4 to 7.5, preferably in the
range of from 6.8 to 7.5, more preferably in the range of from 7.0
to 7.4, preferably selected from the group consisting of a
phosphate buffer comprising NaH.sub.2PO.sub.4 and
Na.sub.2HPO.sub.4, a HEPES buffer comprising
2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid, a TRIS
buffer comprising tris(hydroxymethyl)-aminomethane and an ammonium
acetate buffer, and more preferably is or comprises an ammonium
acetate buffer, [0181] in a total amount in the range of from 0.1
to 10 wt.-%, preferably in a total amount in the range of from 0.2
to 5 wt.-%, more preferably in a total amount in the range of from
0.3 to 3 wt.-%, based on the total weight of the composition;
[0182] (G) water as balance to a total of 100 wt.-% of the
composition in each case, and [0183] (H) one or more water-miscible
organic solvents, preferably selected from the group consisting of
tetrahydrofuran (THF), N-methylpyrrolidone (NMP), dimethyl
formamide (DMF), dimethyl sulfoxide (DMSO) and sulfolane
(2,3,4,5-tetrahydrothiophene-1,1-dioxide) and mixtures thereof,
[0184] in a total amount in the range of from 0 to 30 wt.-%,
preferably in the range of from 0 to 10 wt.-%, more preferably in a
total amount in the range of from 0 to 7.5 wt.-%, even more
preferably in a total amount in the range of from 0 to 6 wt.-%,
based on the total weight of the composition,
[0185] wherein the pH of the composition is in the range of from
6.4 to 7.5, preferably in the range of from 6.8 to 7.5, more
preferably in the range of from 7.0 to 7.4, and
[0186] wherein the wt.-% total amounts of components (A), (B), (C),
(D), (E), (F), (G) and (if present) (H) add to 100 wt.-% in each
case.
[0187] In the above-defined particularly preferred composition of
the first preferred variant of the invention, the preferred or more
preferred components (A), (B), (C), (D), (E), (F) and/or
(optionally) (H) and/or the above-defined amounts or preferred
amounts of components (A), (B), (C), (D), (E), (F) and (optionally)
(H) can be combined to result in an even more preferred composition
according to the first preferred variant of the invention.
[0188] A composition according to the first preferred variant of
the invention as defined herein (or a composition according to the
first preferred variant of the invention as described above as
being preferred) is specifically preferred wherein the composition
consists of [0189] (A) 4-methylmorpholine-4-oxide as solubilizer,
[0190] preferably in a total amount in the range of from 0.01 to 20
wt.-%, more preferably in the range of from 2 to 12 wt.-%, even
more preferably in the range of from 2 to 6 wt.-%, based on the
total weight of the composition; [0191] (B) ammonium fluoride as
etchant, [0192] preferably in a total amount in the range of from
0.01 to 0.1 wt.-%, more preferably in a total amount in the range
of from 0.02 to 0.08 wt.-%, based on the total weight of the
composition; [0193] (C) one or more corrosion inhibitors, selected
from the group consisting of benzotriazole, 6-methyl-benzotriazole
and mixtures thereof, [0194] preferably in a total amount in the
range of from 0.01 to 4 wt.-%, more preferably in a total amount in
the range of from 0.1 to 2 wt.-%, even more preferably in a total
amount in the range of from 0.2 to 1.5 wt.-%, based on the total
weight of the composition; [0195] (D)
1,2-cyclohexylenedinitrilotetraacetic acid as chelating agent,
[0196] preferably in a total amount in the range of from 0.01 to 4
wt.-%, more preferably in a total amount in the range of from 0.02
to 1 wt.-%, even more preferably in a total amount in the range of
from 0.05 to 0.8 wt.-%, based on the total weight of the
composition; [0197] (E) one or more surfactants wherein the or at
least one of the one or more surfactants is a perfluorinated,
N-substituted alkylsulfonamide ammonium salt, [0198] preferably in
a total amount in the range of from 0.0001 to 1 wt.-%, more
preferably in a total amount in the range of from 0.001 to 0.5
wt.-%, even more preferably in a total amount in the range of from
0.002 to 0.1 wt.-%, based on the total weight of the composition;
[0199] (F) a buffering system which is suitable to buffer the pH of
the composition in the range of from 6.4 to 7.5, preferably in the
range of from 6.8 to 7.5, more preferably in the range of from 7.0
to 7.4, and which is preferably an ammonium acetate buffer, [0200]
preferably in a total amount in the range of from 0.1 to 10 wt.-%,
more preferably in a total amount in the range of from 0.2 to 5
wt.-%, even more preferably in a total amount in the range of from
0.3 to 3 wt.-%, based on the total weight of the composition and
[0201] (G) water as balance to a total of 100 wt.-% of the
composition in each case,
[0202] wherein the pH of the composition is in the range of from
6.4 to 7.5, preferably in the range of from 6.8 to 7.5, more
preferably in the range of from 7.0 to 7.4, and
[0203] wherein preferably the wt.-% total amounts of components
(A), (B), (C), (D), (E), (F) and (G) add to 100 wt.-% in each
case.
[0204] A composition according to the second preferred variant of
the invention as defined herein (or a composition according to the
second preferred variant of the invention as described above or
below as being preferred) is preferred wherein: [0205] (A) the or
at least one component (A) is a compound of formula I as defined
above (or a preferred compound of formula I as defined above) and
preferably the or at least one component (A) is N-formylmorpholine,
[0206] and preferably component (A) is present in a total amount in
the range of from 0.01 to 20 wt.-%, more preferably in the range of
from 2 to 15 wt.-%, even more preferably in the range of from 2 to
12 wt.-% and yet even more preferably in the range of from 5 to 12
wt.-%, based on the total weight of the composition.
[0207] A composition according to the second preferred variant of
the invention as defined herein (or a composition according to the
second preferred variant of the invention as described above or
below as being preferred) is also preferred wherein: [0208] (B)
component (B) is selected from the group consisting of ammonium
fluoride, ammonium bifluoride, triethanolammonium fluoride,
diglycolammonium fluoride, methyldiethanolammonium fluoride,
tetramethylammonium fluoride, triethylamine trihydrofluoride,
hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid,
ammonium tetrafluoroborate, fluoroacetic acid, ammonium
fluoroacetate, trifluoroacetic acid, fluorosilicic acid, ammonium
fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures
thereof; [0209] wherein preferably the or at least one component
(B) is ammonium fluoride and more preferably component (B) is
ammonium fluoride, [0210] and preferably component (B) is present
in a total amount in the range of from 0.01 to 0.1 wt.-%, more
preferably in a total amount in the range of from 0.02 to 0.08
wt.-%, based on the total weight of the composition.
[0211] A composition according to the second preferred variant of
the invention as defined herein (or a composition according to the
second preferred variant of the invention as described above or
below as being preferred) is also preferred wherein: [0212] (C) the
or at least one component (C) is selected from the group consisting
of [0213] benzotriazole which is unsubstituted or substituted once
or twice, preferably once, independently by C.sub.1-4-alkyl and/or
(preferably "or") by halogen; [0214] succinic acid and [0215]
mixtures thereof; [0216] and preferably component (C) is present in
a total amount in the range of from 0.01 to 4 wt.-%, more
preferably in a total amount in the range of from 0.1 to 2 wt.-%
and yet more preferably in a total amount in the range of from 0.2
to 1.5 wt.-%, based on the total weight of the composition.
[0217] A composition according to the second preferred variant of
the invention as defined herein (or a composition according to the
second preferred variant of the invention as described above or
below as being preferred) is likewise preferred wherein: [0218] (D)
the or at least one component (D) is histidine, preferably
L-histidine; [0219] and preferably component (D) is present in a
total amount in the range of from 0.01 to 4 wt.-%, more preferably
in a total amount in the range of from 0.02 to 1 wt.-% and yet more
preferably in a total amount in the range of from 0.05 to 0.8
wt.-%, based on the total weight of the composition.
[0220] A composition according to the second preferred variant of
the invention as defined herein (or a composition according to the
second preferred variant of the invention as described above or
below as being preferred) is particularly preferred wherein: [0221]
(A) the or at least one component (A) is a compound of formula I as
defined above (or a preferred compound of formula I as defined
above) and preferably the or at least one component (A) is
N-formylmorpholine, [0222] and preferably is present in a total
amount in the range of from 0.01 to 20 wt.-%, more preferably in
the range of from 2 to 15 wt.-%, even more preferably in the range
of from 2 to 12 wt.-% and yet even more preferably in the range of
from 5 to 12 wt.-%, based on the total weight of the composition;
[0223] (B) component (B) is selected from the group consisting of
ammonium fluoride, ammonium bifluoride, triethanolammonium
fluoride, diglycolammonium fluoride, methyldiethanolammonium
fluoride, tetramethylammonium fluoride, triethylamine
trihydrofluoride, hydrogen fluoride, fluoroboric acid,
tetrafluoroboric acid, ammonium tetra-fluoroborate, fluoroacetic
acid, ammonium fluoroacetate, trifluoroacetic acid, fluoro-silicic
acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate
and mixtures thereof; [0224] wherein preferably the or at least one
component (B) is ammonium fluoride and more preferably component
(B) is ammonium fluoride, [0225] and preferably is present in a
total amount in the range of from 0.01 to 0.1 wt.-%, more
preferably in a total amount in the range of from 0.02 to 0.08
wt.-%, based on the total weight of the composition; [0226] (C) the
or at least one component (C) is selected from the group consisting
of [0227] benzotriazole which is unsubstituted or substituted once
or twice, preferably once, independently by 014-alkyl and/or
(preferably "or") by halogen; [0228] succinic acid and [0229]
mixtures thereof; [0230] and preferably is present in a total
amount in the range of from 0.01 to 4 wt.-%, more preferably in a
total amount in the range of from 0.1 to 2 wt.-% and yet more
preferably in a total amount in the range of from 0.2 to 1.5 wt.-%,
based on the total weight of the composition; [0231] (D) the or at
least one component (D) is histidine, preferably L-histidine;
[0232] and preferably is present in a total amount in the range of
from 0.01 to 4 wt.-%, more preferably in a total amount in the
range of from 0.02 to 1 wt.-% and yet more preferably in a total
amount in the range of from 0.05 to 0.8 wt.-%, based on the total
weight of the composition; and [0233] (G) component (G) is water,
and preferably is present as balance to a total of 100 wt.-% of the
composition in each case,
[0234] wherein the pH of the composition is in the range of from
3.5 to 6, preferably in the range of from 4.0 to 5.5 and
[0235] wherein preferably the wt.-% total amounts of components
(A), (B), (C), (D) and (G) add to 100 wt.-% in each case.
[0236] A composition according to the second preferred variant of
the invention as defined herein (or a composition according to the
second preferred variant of the invention as described above or
below as being preferred) is also preferred wherein: [0237] (A)
component (A) is a compound of formula I as defined above (or a
preferred compound of formula I as defined above), wherein
preferably component (A) is N-formyl-morpholine, [0238] and is
present in a total amount in the range of from 0.01 to 20 wt.-%,
preferably in the range of from 2 to 15 wt.-%, more preferably in
the range of from 2 to 12 wt.-% and even more preferably in the
range of from 5 to 12 wt.-%, based on the total weight of the
composition; [0239] (B) component (B) is selected from the group
consisting of ammonium fluoride, ammonium bifluoride,
triethanolammonium fluoride, diglycolammonium fluoride,
methyldiethanolammonium fluoride, tetramethylammonium fluoride,
triethylamine trihydrofluoride, hydrogen fluoride, fluoroboric
acid, tetrafluoroboric acid, ammonium tetra-fluoroborate,
fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid,
fluoro-silicic acid, ammonium fluorosilicate, tetrabutylammonium
tetrafluoroborate and mixtures thereof; [0240] wherein preferably
the or at least one component (B) is ammonium fluoride and more
preferably component (B) is ammonium fluoride, [0241] and is
present in a total amount in the range of from 0.01 to 0.1 wt.-%,
preferably in a total amount in the range of from 0.02 to 0.08
wt.-%, based on the total weight of the composition; [0242] (C)
component (C) is selected from the group consisting of [0243]
benzotriazole which is unsubstituted or substituted once or twice,
preferably once, independently by 014-alkyl and/or (preferably
"or") by halogen; [0244] succinic acid and [0245] mixtures thereof;
[0246] and is present in a total amount in the range of from 0.01
to 4 wt.-%, preferably in a total amount in the range of from 0.1
to 2 wt.-%, more preferably in a total amount in the range of from
0.2 to 1.5 wt.-%, based on the total weight of the composition
[0247] (D) component (D) is histidine, preferably L-histidine;
[0248] and is present in a total amount in the range of from 0.01
to 4 wt.-%, preferably in a total amount in the range of from 0.02
to 1 wt.-%, more preferably in a total amount in the range of from
0.05 to 0.8 wt.-%, based on the total weight of the composition;
and [0249] (G) component (G) is water and is present as balance to
a total of 100 wt.-% of the composition in each case,
[0250] wherein the pH of the composition is in the range of from
3.5 to 6, preferably in the range of from 4.0 to 5.5 and
[0251] wherein the wt.-% total amounts of components (A), (B), (C),
(D) and (G) add to 100 wt.-% in each case.
[0252] It has been found in own experiments that a composition
according to the second preferred variant which comprises
histidine, preferably L-histidine, as the or at least one component
(D), in particular as the component (D), shows a more selective
etch rate in the presence of a cobalt layer than a composition
according to the second preferred variant which does not comprise
histidine as the or at least one component (D), in particular as
the component (D).
[0253] A composition according to the second preferred variant of
the invention as defined herein (or a composition according to the
second preferred variant of the invention as described above or
below as being preferred) is also preferred wherein the or at least
one component (A) is N-formylmorpholine (CAS RN 4394-85-8) and
wherein preferably component (A) is N-formylmorpholine.
[0254] Compositions according to the second preferred variant of
the invention comprising N-formylmorpholine as solubilizer
component (A), in particular in the preferred total amounts as
specified above, have shown excellent stability of the composition
against precipitation, and enhanced solubility, even at
temperatures below room temperature.
[0255] Compositions according to the second preferred variant of
the invention wherein component (C) is selected from the group
consisting of [0256] benzotriazole which is unsubstituted or
substituted once or twice, preferably once, independently by
C.sub.1-4-alkyl and/or (preferably "or") halogen; preferably
5-methyl-2H-benzotriazole and 5-chloro-2H-benzotriazole; [0257]
succinic acid and [0258] mixtures thereof,
[0259] have shown a stable and reproducible selective etch rate for
etching a layer comprising or consisting of an aluminium compound,
in particular of aluminium oxide, in the presence of a layer of a
low-k material and/or a layer comprising copper and/or cobalt, in
particular in the presence of a layer of a low-k material and/or a
cobalt layer (i.e. a selective etch rate in the presence of a
cobalt layer).
[0260] Particularly preferred is a composition according to the
second preferred variant of the invention as defined herein (or a
composition according to the second preferred variant of the
invention as described above or below as being preferred),
comprising or consisting of [0261] (A) N-formylmorpholine as
solubilizer, [0262] preferably in a total amount in the range of
from 0.01 to 20 wt.-%, more preferably in the range of from 2 to 15
wt.-%, even more preferably in the range of from 2 to 12 wt.-% and
yet even more preferably in the range of from 5 to 12 wt.-%, based
on the total weight of the composition; [0263] (B) ammonium
fluoride as etchant; [0264] preferably in a total amount in the
range of from 0.01 to 0.1 wt.-%, more preferably in a total amount
in the range of from 0.02 to 0.08 wt.-%, based on the total weight
of the composition; [0265] (C) a corrosion inhibitor selected from
the group consisting of [0266] 5-methyl-2H-benzotriazole, [0267]
5-chloro-2H-benzotriazole, [0268] succinic acid and [0269] mixtures
thereof; [0270] preferably in a total amount in the range of from
0.01 to 4 wt.-%, more preferably in a total amount in the range of
from 0.1 to 2 wt.-%, yet more preferably in a total amount in the
range of from 0.2 to 1.5 wt.-%, based on the total weight of the
composition [0271] (D) histidine, preferably L-histidine, as
chelating agent; [0272] preferably in a total amount in the range
of from 0.01 to 4 wt.-%, more preferably in a total amount in the
range of from 0.02 to 1 wt.-%, yet more preferably in a total
amount in the range of from 0.05 to 0.8 wt.-%, based on the total
weight of the composition; and [0273] (G) water, preferably as
balance to a total of 100 wt.-% of the composition in each
case,
[0274] wherein the pH of the composition is in the range of from
3.5 to 6, preferably in the range of from 4.0 to 5.5 and
[0275] wherein preferably the wt.-% total amounts of components
(A), (B), (C), (D) and (G) add to 100 wt.-% in each case.
[0276] The present invention also relates to the use of a
composition according to the invention (including a use of the
composition of the first preferred variant and of the composition
of the second preferred variant) as defined herein (or a respective
use according to the invention as described herein as being
preferred), [0277] for selectively etching a layer comprising an
aluminium compound, preferably of aluminium oxide, in the presence
of a layer of a low-k material and/or a layer comprising copper
and/or cobalt; [0278] preferably in the presence of a layer of a
low-k material and/or a layer comprising copper, preferably a
copper layer, where a composition of the first preferred variant of
the present invention is used; [0279] and/or preferably in the
presence of a layer of a low-k material and/or a layer comprising
cobalt, preferably a cobalt layer, where a composition of the
second preferred variant of the present invention is used; and/or
[0280] for selectively removing from a substrate a layer comprising
an aluminium compound, preferably aluminium oxide, in the presence
of a layer of a low-k material and/or a layer comprising copper
and/or cobalt; [0281] preferably in the presence of a layer of a
low-k material and/or a layer comprising copper, preferably a
copper layer, where a composition of the first preferred variant of
the present invention is used; [0282] and/or preferably in the
presence of a layer of a low-k material and/or a layer comprising
cobalt, preferably a cobalt layer, where a composition of the
second preferred variant of the present invention is used; and/or
[0283] for selectively removing from the surface of a semiconductor
substrate a layer comprising an aluminium compound, preferably
aluminium oxide, in the presence of a layer of a low-k material
and/or a layer comprising copper and/or cobalt; [0284] preferably
in the presence of a layer of a low-k material and/or a layer
comprising copper where a composition of the first preferred
variant of the present invention is used; [0285] and/or preferably
in the presence of a layer of a low-k material and/or a layer
comprising cobalt, preferably a cobalt layer, where a composition
of the second preferred variant of the present invention is
used.
[0286] Generally, all aspects of the present invention discussed
herein in the context of the inventive composition (including the
first preferred variant and the second preferred variant) apply
mutatis mutandis to the use of said composition according to the
present invention (including the use of the first preferred variant
and the use of the second preferred variant), as defined here above
and below. And likewise all aspects of the use of said composition
according to the present invention discussed herein apply mutatis
mutandis to the inventive composition.
[0287] A use according to the invention (including a use of the
composition of the first preferred variant and of the composition
of the second preferred variant) as defined above (or a respective
use according to the invention as described herein as being
preferred) is particularly preferred wherein the use is in a
two-step-process of removing [0288] (i) a metal hard mask,
preferably selected from the group consisting of a Ti hard mask, a
TiN hard mask, a Ta hard mask, a TaN hard mask, an Al hard mask, a
HfO.sub.x (i.e. Hafnium oxide) hard mask and an AlCu (i.e. an AlCu
alloy) hard mask, more preferably a TiN hard mask and [0289] (ii)
an etch-stop layer of an aluminium compound deposited on a layer
comprising copper, preferably a copper layer, and/or a layer
comprising cobalt, preferably a cobalt layer,
[0290] wherein preferably the use is in the second step (ii);
[0291] and wherein preferably the use of a composition of the first
preferred variant of the present invention is in said two-step
process wherein the etch-stop layer of an aluminium compound is
deposited on a layer comprising copper, preferably a copper layer;
[0292] and/or wherein preferably the use of a composition of the
second preferred variant of the present invention is in said
two-step process wherein the etch-stop layer of an aluminium
compound is deposited on a layer comprising cobalt, preferably a
cobalt layer.
[0293] In the preferred use in the two-step process according to
the invention as defined here above, preferably the process step
(i) of removing a metal hard mask is the first process step and the
process step (ii) of removing an etch-stop layer is the second
process step. Said second process step can be performed directly
after said first process step or there can be performed one or more
other process steps between performing said first process step and
said second process step.
[0294] A use according to the invention (including a use of the
composition of the first preferred variant and of the composition
of the second preferred variant) as defined above (or a respective
use according to the invention as described herein as being
preferred) is also preferred wherein the etch-stop layer of an
aluminium compound, preferably of aluminium oxide, before etching
has a maximum thickness of 30 nm or below, preferably of 20 nm or
below, more preferably of 10 nm or below and even more preferably
of 5 nm or below.
[0295] A use according to the invention as defined above (or a use
according to the invention as described herein as being preferred)
is also preferred wherein the two-step process is part of a
damascene process for manufacturing integrated circuit
interconnects.
[0296] The present invention also relates to a process for the
manufacture of a semiconductor device, comprising the step of
selectively etching at least one layer comprising or consisting of
an aluminium compound, preferably of aluminium oxide, in the
presence of a layer of a low-k material and/or a layer comprising
copper and/or cobalt, by contacting the at least one layer of an
aluminium compound at least once with a composition (including a
composition of the first preferred variant and a composition of the
second preferred variant) according to the invention as defined
herein (or a composition according to the invention as described
herein as being preferred).
[0297] Where the process comprises the step of selectively etching
at least one layer comprising or consisting of an aluminium
compound, preferably of aluminium oxide, in the presence of a layer
of a low-k material and/or a layer comprising copper, preferably a
copper layer, contacting the at least one layer of an aluminium
compound at least once with a composition according to the first
preferred variant of the invention as defined herein (or a
composition according to the first preferred variant of the
invention as described herein as being preferred) is preferred.
[0298] Where the process comprises the step of selectively etching
at least one layer comprising or consisting of an aluminium
compound, preferably of aluminium oxide, in the presence of a layer
of a low-k material and/or a layer comprising cobalt, preferably a
cobalt layer, contacting the at least one layer of an aluminium
compound at least once with a composition according to the second
preferred variant of the invention as defined herein (or a
composition according to the second preferred variant of the
invention as described herein as being preferred) is preferred.
[0299] Generally, all aspects of the present invention discussed
herein in the context of the inventive composition and/or the
inventive use of said composition apply mutatis mutandis to the
process for the manufacture of a semiconductor device of the
present invention, as defined here above and below. And likewise
all aspects of the process for the manufacture of a semiconductor
device of the present invention apply mutatis mutandis to the
inventive composition and/or the inventive use of said
composition.
[0300] A process according to the invention as defined above is
preferred wherein said etching is conducted in the presence of a
layer of a low-k material and a layer comprising copper and/or
cobalt, preferably in the presence of a layer of a low-k material
and a layer comprising copper, preferably a copper layer, where a
composition according to the first preferred variant of the
invention as defined herein (or a composition according to the
first preferred variant of the invention as described herein as
being preferred) is used and preferably in the presence of a layer
of a low-k material and a layer comprising cobalt, preferably a
cobalt layer, where a composition according to the second preferred
variant of the invention as defined herein (or a composition
according to the second preferred variant of the invention as
described herein as being preferred) is used.
[0301] A process according to the invention as defined above (or a
process according to the invention as described herein as being
preferred) is also preferred wherein said at least one layer
comprising or consisting of an aluminium compound is a top layer
and the layer comprising copper and/or cobalt, is a lower layer
covered by the top layer, with or without at least one further
layer being present in between the top layer and the lower layer,
preferably without at least one (i.e. without any) further layer
being present in between the top layer and the lower layer.
[0302] A process according to the invention as defined above (or a
process according to the invention as described herein as being
preferred) is also preferred wherein the process for manufacturing
a semiconductor device is a damascene process for manufacturing
integrated circuit interconnects.
[0303] A process according to the invention as defined above (or a
process according to the invention as described herein as being
preferred) is also preferred wherein the process comprises a
two-step cleaning process, preferably a cleaning process for a
semiconductor device, comprising the steps of [0304] removing in a
first step a metal hard mask, preferably selected from the group
consisting of a Ti hard mask, a TiN hard mask, a Ta hard mask, a
TaN hard mask, an Al hard mask, a HfO.sub.x (i.e. Hafniumoxide)
hard mask and an AlCu hard mask; more preferably a TiN hard mask,
[0305] before selectively etching in a separate second step the at
least one layer comprising or consisting of an aluminium compound,
preferably of aluminium oxide.
[0306] Preferably the metal hard mask in the preferred process of
the invention as defined here above is selected from the group
consisting of a Ti hard mask, a TiN hard mask, a Ta hard mask, a
TaN hard mask, an Al hard mask, a HfO.sub.x (i.e. Hafniumoxide)
hard mask and an AlCu (i.e. an AlCu alloy) hard mask. More
preferably the metal hard mask is a TiN hard mask.
[0307] In the preferred two-step process according to the invention
as defined here above, said separate second process step can be
performed directly after said first process step or there can be
performed one or more other process steps between performing said
first process step and said separate second process step.
[0308] A process according to the invention as defined above (or a
process according to the invention as described herein as being
preferred) is also preferred wherein the at least one layer
comprising or consisting of an aluminium compound, preferably of
aluminium oxide, before etching has a maximum thickness of 30 nm or
below, preferably of 20 nm or below, more preferably of 10 nm or
below and even more preferably of 5 nm or below. In some cases a
process according to the invention as defined above (or a process
according to the invention as described herein as being preferred)
is preferred wherein the at least one layer comprising or
consisting of an aluminium compound, preferably of aluminium oxide,
has a maximum thickness of 2 nm or below, preferably of 1 nm or
below, more preferably of 0.5 nm or below.
EXAMPLES
[0309] The following examples are meant to further explain the
invention without limiting its scope.
Example 1: Preparation of Compositions According to the Invention
(First Preferred Variant) and of Comparative Compositions (not
According to the Invention)
[0310] The following preferred compositions according to the first
preferred variant of the invention (marked as "I", i.e.
compositions I1 to I8) were prepared by mixing the components (A)
to (G) or (A) to (H), as applicable. Details are given below in
table 1a. Further compositions according to the invention (marked
as "I", i.e. compositions I9 to I13) were prepared by mixing the
components (A) to (G) or (A) to (H), as applicable. Details are
given below in table 1b. In addition, comparative compositions (not
according to the invention, marked as "C", i.e. compositions C1 to
C2) were also prepared in a similar manner, as shown in more detail
in table 1c below. For adjusting the pH of the different
compositions, a total amount of an acidic buffer component (acetic
acid as a 96% w/w solution in water where an acetate buffer was
used) was added to the composition, followed by a suitable amount
of the corresponding basic (alkaline) buffer component (ammonia as
a 29 wt.-% solution in water where an acetate buffer was used)
until the desired pH of the composition was reached.
TABLE-US-00001 TABLE 1a Preferred test compositions according to
the invention (first preferred variant) Composition [wt. %]
Component Constituent I1 I2 I3 I4 I5 I6 I7 I8 (A) 4-MM-4-O 5.0 5.0
2.5 5.0 5.0 5.0 5.0 5.0 (B) NH.sub.4F 0.06 0.03 0.06 0.06 0.06 0.06
0.06 0.06 (C) 6-Me-BTA 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.25 (C) BTA 0.5
0.5 0.5 0.5 0.5 0.5 0.5 0.25 (D) CDTA 0.1 0.1 0.1 0.1 0.1 0.1 0.1
0.1 (E) PNAAS 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.004 (F) Acetic
acid 0.5 0.5 0.3 0.3 0.7 0.6 0.6 0.6 (F) Ammonia 0.2 0.2 0.2 0.2
0.3 0.2 0.2 0.2 (G) Water 93.12 93.15 90.92 88.32 87.82 88.02 93.02
93.536 (H) Sulfolane 0 0 5.0 5.0 5.0 5.0 0 0 -- pH: 7.4 7.4 7.3 7.3
7.1 6.4 6.4 7.0
TABLE-US-00002 TABLE 1b Further test compositions according to the
invention (first preferred variant) Com- Composition [wt. %] ponent
Constituent I9 I10 I11 I12 I13 (A) 4-MM-4-O 5.0 5.0 7.5 7.5 7.5 (B)
NH.sub.4F 0.06 0.06 0.06 0.06 0.06 (C) 6-Me-BTA 0.5 0.5 0.5 0.5 0.6
(C) BTA 0.5 0.5 0.5 0.5 0.6 (D) CDTA 0.1 0.1 0.1 0.1 0.1 (E) PNAAS
0.02 0.02 0.02 0 0 (F) Acetic acid 0.75 0.75 0.5 0.5 0.5 (F)
Ammonia 0.3 0.3 0.2 0.2 0.22 (G) Water 87.77 92.77 83.12 83.14
82.92 (H) Sulfalane 5.0 0 0 0 0 -- BDG 0 0 7.5 7.5 7.5 -- pH: 6.3
6.3 7.4 7.4 7.4
TABLE-US-00003 TABLE 1c Comparative test compositions Com-
Composition po- [wt.-%] nent Constituent C1 C2 (A) 4-MM-4-O 7.5 7.5
(B) NH.sub.4F 0.06 0.06 (C) 6-Me-BTA 0 0 (C) BTA 0 0 (D) CDTA 0.1
0.1 (E) PNAAS 0.02 0 (F) Acetic acid 0.5 0.5 (F) Ammonia* 0.2 0.22
(G) Water 84.1 84.12 (H) Sulfolane 0 0 -- BDG 7.5 7.5 -- pH: 8.2
8.2 BDG: butyl diglycol (diethyleneglycol butyl ether) All wt.-% of
constituents in tables 1a, 1b and 1c are calculated as pure,
undiluted compounds.
Example 2: Determination of Aluminium Oxide (AlOx) and Copper Etch
Results of Test Compositions (First Preferred Variant)
[0311] Si wafers or wafer pieces (collectively referred to as "test
wafers" in the following) with the appropriate types of outer
layers were obtained from commercial sources. The test wafers were
pre-treated as applicable: Cu was immersed into an oxalic acid
solution for 20-30 s and then rinsed with water and dried.
AlO.sub.x-coated surfaces were not pre-treated. The copper and
AlO.sub.x-layers on the test wafers had a thickness of 100 .ANG. in
each case.
[0312] Aluminium oxide (AlO.sub.x)-coated surfaces were used as a
representative model for layers of (comprising or consisting of) an
aluminium compound (as defined above).
[0313] The test compositions (as defined in tables 1a, 1b and 1c)
were prepared and the test wafers (see above) were contacted with
the test compositions in a glass beaker, at a temperature of
60.degree. C. and for a reaction time period of 1 min in the case
of AlO.sub.x surfaces and for a reaction time period of from 5 min
to 10 min in the case of Cu surfaces, and then withdrawn from the
test compositions, rinsed with water or isopropanol and dried with
nitrogen gas.
[0314] The thicknesses of the copper and aluminium oxide layers on
the test wafers were determined before and after contact with the
test compositions by X-ray fluorescence analysis. Experiments were
repeated at least three times to ensure reproducibility.
[0315] The difference of the measured value of the thickness of a
copper or an AlO.sub.x layer, respectively, before its contact with
a test composition, minus the measured value of the thickness of
the same copper or aluminium oxide layer, respectively, after its
contact with the test composition was determined in each case as
the total etch loss and the total etch loss so determined was
divided by the process time to yield the etch rate. The results are
shown in table 2 below as etch rate of a layer after contact with a
test composition in .ANG./min (each given value in table 2
representing the average of at least three experiments).
TABLE-US-00004 TABLE 2 Aluminium oxide and copper etch results of
the test compositions (first preferred variant) Etch rates per
layer [.ANG./min] Composition Cu AlO.sub.x I1 0.1 96 I2 0 50 I3 0.1
55 I4 0.1 53 I5 0.1 79.1 I6 0.1 88 I7 0.1 >100 I9 0.1 >100
I10 0.1 >100 I11 5 >100 I12 7.4 >100 I13 6 >100 C1
>50 25 C2 >50 22
[0316] Etch rate values of ">100" in table 2 for
AlO.sub.x-layers on a Si wafer have the meaning that the entire
AlO.sub.x-layer was removed within the applicable reaction time
period of one minute or before said applicable reaction time period
of one minute had passed, with the effect that an exact etch rate
could not be measured in these cases (such cases also being
referred to as cases of "over-etching" hereinafter).
[0317] From the test results received, the following observations
can be made:
[0318] The preferred test compositions according to the first
preferred variant of the invention listed in table 1a (I1, I2, I3,
I4, I5, I6 and I7) all show a high etch rate selectivity for
etching of AlO.sub.x vs Cu layers (see results in table 2).
Occurrence of "over-etching" (i.e. values of >100% etching) of
the AlO.sub.x-layer first disappears (in the time period applied)
in compositions with pH value of 6.4 (or higher; see compositions
I6 and I7). Compositions which have a pH of 6.4 (or higher, up to a
pH of 7.5) are therefore regarded as preferred test compositions
according to the invention.
[0319] Over-etching results demonstrate that deviations from
optimal pH or composition can lead to an unfavourable increase in
etch rates and hence in a loss of etch rate selectivity. A mere
reduction of etch times in order to optimize etch results is not
preferred as this can lead to more inaccuracy in etch time due to
practical limitations. For example, the etch time of 1 min as
selected for etching the AlO.sub.x-layers in the present examples
is an industrially relevant time period. For practical reasons, the
etch rate achieved with a certain composition is relevant, not only
the total etch loss.
[0320] In the pH range most preferred in practice (pH 6.8 to 7.5),
compositions according to the first preferred variant of the
invention which comprise an organic solvent have a stronger
tendency to show incomplete etching results, with a sharp decline
between pH values 7.1 and 7.3 (see compositions I4 and I5). In
contrast, composition I1 which does not comprise organic solvents
shows a high but controlled etch rate for the Cu layer (but no
over-etching) in the preferred pH range, and a high etch rate
selectivity. Compositions according to the first preferred variant
of the invention which do not comprise organic solvents (see e.g.
compositions I1 and I2) are therefore preferred.
[0321] Test compositions according to the first preferred variant
of the invention listed in table 1b show a good (see compositions
I9, I10 containing no organic solvent or a preferred organic
solvent) or satisfactory (see compositions I11, I12 and I13, all
containing butyl diglycol as a less preferred organic solvent) etch
rate selectivity for etching of AlO.sub.x vs Cu layers. All test
compositions listed in table 1b showed over-etching under the
reaction conditions applied.
[0322] Comparative compositions listed in table 1c (C1, C2) did not
show a satisfactory etch rate selectivity for etching of AlO.sub.x
vs Cu layers, i.e. significant unfavourable etching of the Cu layer
was observed in each case (see table 2 above).
Example 3: Preparation of Compositions According to the Invention
(Second Preferred Variant) and of Comparative Compositions (not
According to the Invention)
[0323] The following compositions according to the second preferred
variant of the invention (compositions I20, I21 and I22) were
prepared by mixing the components (A) to (D) and (G). Details are
given below in table 3. In addition, comparative compositions (not
according to the invention, compositions C20 and C21) were also
prepared in a similar manner, as shown in more detail in table 4
below.
TABLE-US-00005 TABLE 3 Test compositions according to the invention
(second preferred variant) Compo- Composition [wt.-%] nent
Constituent I20 I21 I22 (A) NFM 10.0 5.0 5.0 (B) NH.sub.4F 0.03
0.03 0.03 (C) 5-Me-BTA 0.75 0.5 0.8 (C) 5-Cl-BTA 0.15 0 0 (C) BTA 0
0.5 0.8 (C) Succinic acid 0.12 0.1 0.1 (D) L-histidine 0.1 0.1 0.1
(G) Water 88.85 93.77 93.17 -- pH: 4.7 4.7 4.7
TABLE-US-00006 TABLE 4 Comparative test compositions Compo-
Composition [wt.-%] nent Constituent C20 C21 (A) NFM 0 0 (B)
NH.sub.4F 0.03 0.03 (C) 5-Me-BTA 0.5 0.5 (C) 5-Cl-BTA 0.1 0 (C) BTA
0 0.5 (C) Succinic acid 0.09 0.09 (D) L-histidine 0.1 0.1 (G) Water
99.28 98.88 (H) DMSO 5.0 5.0 -- pH 4.7 4.7 DMSO: dimethyl sulfoxide
All wt.-% of constituents in tables 3 and 4 are calculated as pure,
undiluted compounds.
Example 4: Determination of Aluminium Oxide (AlO.sub.x) and Cobalt
Etch Results of Test Compositions (Second Preferred Variant)
[0324] Si wafers or wafer pieces (collectively referred to as "test
wafers" in the following) with the appropriate types of outer
layers (Co; AlO.sub.x; plasma-deposited tetraethyl orthosilicate
("TEOS")) were obtained from commercial sources. The test wafers
were pre-treated as applicable: Co was immersed into an oxalic acid
solution for 20-30 s and then rinsed with water and dried.
AlO.sub.x-coated surfaces were not pre-treated.
[0325] Aluminium oxide (AlO.sub.x)-coated surfaces were used as a
representative model for layers of (comprising or consisting of) an
aluminium compound (as defined above).
[0326] The test compositions (as defined in tables 3 and 4) were
prepared and the test wafers (see above) were contacted with the
test compositions in a glass beaker, at a temperature of 40.degree.
C. and for a reaction time period of 1 min in the case of
cobalt-coated surfaces, at a temperature of 35.degree. C. and fora
reaction time period of 15 s in the case of aluminium oxide-coated
surfaces and at a temperature of 35.degree. C. and for a reaction
time period of 10 min in the case of TEOS surfaces. The test wafers
were then withdrawn from the test compositions, rinsed with water
or isopropanol and dried with nitrogen gas.
[0327] The thicknesses of the cobalt, TEOS and aluminium oxide
layers on the test wafers were determined before and after contact
with the test compositions by X-ray fluorescence analysis.
Experiments were repeated at least three times to ensure
reproducibility.
[0328] The difference of the measured value of the thickness of a
cobalt, TEOS or AlOx layer, respectively, before its contact with a
test composition, minus the measured value of the thickness of the
same cobalt, TEOS or AlOx layer, respectively, after its contact
with the test composition was determined in each case as the total
etch loss and the total etch loss so determined was divided by the
process time to yield the etch rate. The results are shown in table
5 below as etch rate of a layer after contact with a test
composition in .ANG./min (each given value in table 5 representing
the average of at least three experiments).
TABLE-US-00007 TABLE 5 Cobalt, TEOS and aluminium oxide etch
results of the test compositions (second preferred variant) Etch
rates per layer [.ANG./min] Composition Co AlO.sub.x TEOS I20 2.6
6.0 <1 I21 6.1 no data no data I22 2.5 no data no data C20 2.0
6.0 <1 C21 5.4 no data no data
[0329] From the test results shown in table 5, the following
observations can be made:
[0330] Composition I20 according to the invention shows a
satisfactory etch rate selectivity for etching of AlO.sub.x vs Co
and TEOS layers.
[0331] Compositions I22 according to the invention and C20
(comparative composition not according to the invention) show
similar satisfactory results regarding etch rate selectivity for
etching of AlO.sub.x vs Co layers (but see results of example 5,
below).
Example 5: Stability of Test Compositions (Second Preferred
Variant) Against Precipitation
[0332] The test composition I20 according to the invention and the
comparative test composition C20 were cooled to 5.degree. C. for 72
h. Immediately after the cooling period, both compositions were
visually inspected for stability of the solution (i.e. precipitated
material).
[0333] It was found that composition I20 according to the invention
had remained clear after the cooling period, indicating stability
of the solution even at lowered temperatures, while comparative
composition C20 showed precipitation of materials, indicating
insufficient stability of the solution at temperatures below room
temperature.
[0334] From these observations it can be concluded that
compositions comprising a solubilizer according to the present
invention (in composition I20: N-formylmorpholine) show enhanced
stability of solution against precipitation in comparison with
compositions comprising no or other solubilizers than the ones
according to the present invention (in comparative composition C20:
DMSO).
[0335] As is known in the field, compositions for etching one or
more materials for use in the manufacture of a semiconductor device
must remain stable under the conditions of manufacture and not,
e.g., form precipitates which can interfere with or corrupt said
manufacture process or its products. Therefore, compositions for
etching one or more materials for use in the manufacture of a
semiconductor device which form precipitates under the conditions
of such manufacture process are not acceptable for industrial
use.
* * * * *