U.S. patent application number 17/805144 was filed with the patent office on 2022-09-22 for composition for cobalt electroplating comprising leveling agent.
The applicant listed for this patent is BASF SE. Invention is credited to Marco ARNOLD, Charlotte EMNET, Nadine ENGELHARDT, Alexander FLUEGEL, Lucas Benjamin HENDERSON, Dieter MAYER.
Application Number | 20220298664 17/805144 |
Document ID | / |
Family ID | 1000006377779 |
Filed Date | 2022-09-22 |
United States Patent
Application |
20220298664 |
Kind Code |
A1 |
ENGELHARDT; Nadine ; et
al. |
September 22, 2022 |
Composition for Cobalt Electroplating Comprising Leveling Agent
Abstract
Described herein is a cobalt electrodeposition composition
including cobalt ions, and particular leveling agents including
X.sup.1--CO--O--R.sup.11, X.sup.1--SO.sub.2--O--R.sup.11,
X.sup.1--PO(OR.sup.11).sub.2, X.sup.1--SO--O--R.sup.11 functional
groups, where X.sup.1 is a divalent group selected from (i) a
chemical bond (ii) aryl, (iii) C.sub.1 to C.sub.12 alkandiyl, which
may be interrupted by O atoms, (iv) an arylalkyl group
--X.sup.11--X.sup.12--, (v) an alkylaryl group
--X.sup.12--X.sup.11-- and (vi)
--(O--C.sub.2H.sub.3R.sup.12).sub.mO--, R.sup.11 is selected from H
and C.sub.1 to C.sub.4 alkyl. R.sup.12 is selected from H and
C.sub.1 to C.sub.4 alkyl, X.sup.12 is a divalent aryl group, and
X.sup.11 is a divalent C.sub.1 to C.sub.15 alkandiyl group.
Inventors: |
ENGELHARDT; Nadine;
(Ludwigshafen, DE) ; MAYER; Dieter; (Lemfoerde,
DE) ; ARNOLD; Marco; (Ludwigshafen, DE) ;
FLUEGEL; Alexander; (Ludwigshafen, DE) ; EMNET;
Charlotte; (Ludwigshafen, DE) ; HENDERSON; Lucas
Benjamin; (Ludwigshafen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BASF SE |
Ludwigshafen am Rhein |
|
DE |
|
|
Family ID: |
1000006377779 |
Appl. No.: |
17/805144 |
Filed: |
June 2, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16762717 |
May 8, 2020 |
11377748 |
|
|
PCT/EP2018/081692 |
Nov 19, 2018 |
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17805144 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 3/18 20130101; C25D
7/123 20130101; C25D 5/02 20130101 |
International
Class: |
C25D 3/18 20060101
C25D003/18; C25D 7/12 20060101 C25D007/12; C25D 5/02 20060101
C25D005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2017 |
EP |
17202568.6 |
Claims
1-16. (canceled)
17. A composition, comprising: (a) metal ions consisting
essentially of cobalt ions, and (b) a leveling agent, wherein the
leveling agent is a compound of formula L2: ##STR00025## or a
compound of formula L4: O-R.sup.1 (L4), or salts thereof, wherein
R.sup.1 is selected from the group consisting of
X.sup.1--CO--O--R.sup.11, X.sup.1--SO.sub.2--O--R.sup.11,
X.sup.1--PO(OR.sup.11).sub.2, and X.sup.1--SO--O--R.sup.11;
R.sup.2, R.sup.3, R.sup.4 are independently selected from the group
consisting of R.sup.1 and (i) H, (ii) aryl, (iii) C.sub.1 to
C.sub.10 alkyl (iv) arylalkyl, (v) alkylaryl, and (vi)
--(O--C.sub.2H.sub.3R.sup.12).sub.m--OH, wherein if one of R.sup.2,
R.sup.3 or R.sup.4 is R.sup.1, remaining R.sup.2, R.sup.3 or
R.sup.4 are different from R.sup.1, O is a C.sub.6 to C.sub.14
carbocyclic or a C.sub.3 to C.sub.10 nitrogen or oxygen containing
heterocyclic aryl group, which is optionally unsubstituted or
substituted by up to three C.sub.1 to C.sub.12 alkyl groups or up
to two OH, NH.sub.2 or NO.sub.2 groups, X.sup.1 is a divalent group
selected from the group consisting of (i) a chemical bond (ii)
aryl, (iii) C.sub.1 to C.sub.12 alkandiyl, which is optionally
interrupted by O atoms, (iv) arylalkyl group
--X.sup.11--X.sup.12--, (v) alkylaryl group --X.sup.12--X.sup.11--,
and (vi) --(O--C.sub.2H.sub.3R.sup.12).sub.mO--, R.sup.11 is
selected from the group consisting of H and C.sub.1 to C.sub.4
alkyl, R.sup.12 is selected from the group consisting of H and
C.sub.1 to C.sub.4 alkyl, X.sup.11 is a divalent C.sub.1 to
C.sub.15 alkandiyl group, X.sup.12 is a divalent aryl group, and m
is an integer from 2 to 50, wherein the composition is essentially
free of any dispersed particles.
18. The composition according to claim 17, wherein R.sup.2, R.sup.3
and R.sup.4 are selected from the group consisting of H, methyl,
ethyl, and propyl.
19. The composition according to claim 17, wherein R.sup.2 and
either R.sup.3 or R.sup.4 are selected from the group consisting of
H, methyl, ethyl, and propyl, and remaining R.sup.3 or R.sup.4 is
R.sup.1.
20. The composition according to claim 17, wherein R.sup.3 and
R.sup.4 are selected from the group consisting of H, methyl, ethyl,
and propyl, and R.sup.2 is R.sup.1.
21. The composition according to claim 17, wherein the leveling
agent is a compound of formula L4a: ##STR00026## wherein R.sup.5,
R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are independently selected
from the group consisting of (i) H and (ii) C.sub.1 to C.sub.6
alkyl.
22. The composition according to claim 17, wherein R.sup.11 is
H.
23. The composition according to claim 17, wherein m is an integer
from 2 to 30.
24. The composition according to claim 17, wherein the leveling
agent is itaconic acid.
25. The composition according to claim 17, wherein the leveling
agent is selected from the group consisting of acrylic acid,
itaconic acid, vinylphosphonic acid, and vinylsulfonic acid.
26. The composition according to claim 17, wherein R.sup.1 is a
sulphonate group.
27. The composition according to claim 17, wherein the leveling
agent is p-toluol sulfonate.
28. The composition according to claim 17, wherein the composition
further comprises a suppressing agent selected from the group
consisting of a hydroxy alkyne or an amino alkyne.
29. A process for depositing cobalt on a semiconductor substrate
comprising a recessed feature having an aperture size below 100 nm,
the process comprising (a) bringing a composition according to
claim 17 into contact with the semiconductor substrate, (b)
applying an electrical potential for a time sufficient to fill the
recessed feature with cobalt.
30. A process according to claim 29, comprising: depositing a
cobalt seed on a dielectric surface of the recessed feature before
the bringing.
31. A process according to claim 29, wherein the recessed feature
has an aperture size of 30 nm or below.
Description
[0001] The present invention relates to a composition for cobalt
electroplating comprising cobalt ions and a leveling agent.
BACKGROUND OF THE INVENTION
[0002] Filling of small features, such as vias and trenches, by
metal electroplating is an essential part of the semiconductor
manufacture process. It is well known, that the presence of organic
substances as additives in the electroplating bath can be crucial
in achieving a uniform metal deposit on a substrate surface and in
avoiding defects, such as voids and seams, within the metal
lines.
[0003] With further decreasing aperture size of recessed features
like vias or trenches the filling of the interconnects with copper
becomes especially challenging, also since the copper seed
deposition by physical vapor deposition (PVD) prior to the copper
electrodeposition might exhibit inhomogeneity and non-conformity
and thus further decreases the aperture sizes particularly at the
top of the apertures. Furthermore, it becomes more and more
interesting to substitute copper by cobalt since cobalt shows less
electromigration into the dielectric.
[0004] For cobalt electroplating several additives were proposed to
ensure void-free filling of submicrometer-sized features.
[0005] US 2011/0163449 A1 discloses a cobalt electrodeposition
process using a bath comprising a cobalt deposition-inhibiting
additive, such as saccharin, coumarin or polyethyleneimine
(PEI).
[0006] US 2009/0188805 A1 discloses a cobalt electrodeposition
process using a bath comprising at least one accelerating,
inhibiting, or depolarizing additive selected from
polyethyleneimine and 2-mercapto-5-benzimidazolesulfonic acid.
[0007] WO2017/004424 discloses a composition for cobalt
electrodeposition comprising SPS as an accelerator, and an
acetylenic suppressor like propargyl alcohol and alkoxylated
propargyl alcohol.
[0008] PCT/EP2017/066896 discloses alkynoles and alkyne amines as
suppressing agents.
[0009] EP 1323848 A1 discloses a nickel electroplating solution
containing a) nickel ions, and b) at least two chelating agents
selected from amino polycarboxylic acids, polycarboxylic acids, and
polyphosphonic acids, wherein the nickel electroplating solution
has a pH of 4 to 9, and a ratio of nickel ions to chloride ions
(Ni.sup.+2/Cl.sup.-1) of 1 or less.
[0010] US 2016/273117 A1 discloses a method for electroplating
cobalt into recessed features on a substrate, the method including:
receiving the substrate in an electroplating chamber, the substrate
including recessed features having a cobalt seed layer thereon, the
cobalt seed layer having a thickness of about 50 A or less, and the
recessed features having a width between about 10-150 nm, immersing
the substrate in electrolyte, the electrolyte including boric acid,
halide ions, cobalt ions, and organic additives for achieving
seam-free bottom-up fill in the recessed features, and
electroplating cobalt into the features under conditions that
provide bottom-up fill.
[0011] The disadvantage of the existing cobalt electrodeposition
baths is its strong mounding effect over dense features.
[0012] There is still a strong need for cobalt electroplating bath
which provides, besides void-free filling of submicrometer-sized
interconnect features, a substantially planar surface over the
filled features.
[0013] It is therefore an object of the present invention to
provide a cobalt electroplating additive having good leveling
properties, in particular leveling agents capable of providing a
substantially planar metal layer and filling features on the
nanometer and on the micrometer scale without substantially forming
defects, such as but not limited to voids, with a cobalt
electroplating bath.
[0014] It is a further object of the present invention to provide a
cobalt electroplating bath capable of depositing a low impurity
metal layer.
SUMMARY OF THE INVENTION
[0015] With the particular vinylic, polyvinylic or aromatic
leveling agents described below the present invention provides a
new class of highly effective leveling agents that provide reduced
mounding above recessed features fully filled with cobalt,
particularly on substrates comprising nanometer-sized interconnect
features, particularly if areas of different feature density and
width are present.
[0016] Therefore, the present invention provides a composition
comprising
[0017] (a) metal ions consisting essentially of cobalt ions,
and
[0018] (b) a leveling agent comprising the structure of formula
L1
[B].sub.n[A].sub.p (L1)
[0019] or having the structure of formula L2
##STR00001##
[0020] or comprising the structure of formula L3a or L3b
##STR00002##
[0021] or having the structure of formula L4
O-R.sup.1 (L4)
[0022] and their salts,
[0023] wherein [0024] R.sup.1 is selected from
X.sup.1--CO--O--R.sup.11, X.sup.1--SO.sub.2--O--R.sup.11,
X.sup.1--PO(OR.sup.11).sub.2, X.sup.1--SO--O--R.sup.11; [0025]
R.sup.2, R.sup.3, R.sup.4 are independently selected from R.sup.1
and (i) H, (ii) aryl, (iii) C.sub.1 to C.sub.10 alkyl (iv)
arylalkyl, (v) alkylaryl, and (vi)
--(O--C.sub.2H.sub.3R.sup.12).sub.m--OH, with the proviso that if
one of R.sup.2, R.sup.3 or R.sup.4 are selected from R.sup.1, the
other groups R.sup.2, R.sup.3 or R.sup.4 are different from
R.sup.1, [0026] O is a C.sub.6 to C.sub.14 carbocyclic or a C.sub.3
to C.sub.10 nitrogen or oxygen containing heterocyclic aryl group,
which may be unsubstituted or substituted by up to three C.sub.1 to
C.sub.12 alkyl groups or up to two OH, NH.sub.2 or NO.sub.2 groups,
[0027] R.sup.31 is selected from R.sup.1, H, OR.sup.5 and R.sup.5,
[0028] R.sup.32 is selected from (i) H and (ii) C.sub.1 to C.sub.6
alkyl, [0029] X.sup.1 is a divalent group selected from (i) a
chemical bond (ii) aryl, (iii) C.sub.1 to C.sub.12 alkandiyl, which
may be interrupted by O atoms, (iv) arylalkyl group
--X.sup.11--X.sup.12--, (v) alkylaryl group --X.sup.12--X.sup.11--
and (vi) --(O--C.sub.2H.sub.3R.sup.12).sub.mO--, [0030] X.sup.2 is
(i) a chemical bond or (ii) methanediyl, [0031] R.sup.11 is
selected from H and C.sub.1 to C.sub.4 alkyl, [0032] R.sup.12 is
selected from H and C.sub.1 to C.sub.4 alkyl, [0033] X.sup.12 is a
divalent aryl group, [0034] X.sup.11 is a divalent C.sub.1 to
C.sub.15 alkandiyl group, [0035] A is a co-monomer selected from
vinyl alcohol, which may optionally be (poly)ethyoxylated, and
acrylamide, [0036] B is selected from formula L1a
[0036] ##STR00003## [0037] n is an integer from 2 to 10,000, [0038]
m is an integer from 2 to 50, [0039] o is an integer from 2 to
1000, and [0040] p is 0 or an integer from 1 to 10,000,
[0041] and wherein the composition is free of any dispersed
particles.
[0042] In another embodiment the present invention provides a
composition comprising [0043] (a) metal ions consisting essentially
of cobalt ions, and [0044] (b) a leveling agent comprising the
structure of formula L1
[0044] [B].sub.n[A].sub.p (L1)
[0045] or having the structure of formula L2
##STR00004##
[0046] or comprising the structure of formula L3a or L3b
##STR00005##
[0047] or having the structure of formula L4
O-R.sup.1 (L4)
[0048] and their salts,
[0049] wherein [0050] R.sup.1 is selected from
X.sup.1--CO--O--R.sup.11, X.sup.1--SO.sub.2--O--R.sup.11,
X.sup.1--PO(OR.sup.11).sub.2, X.sup.1--SO--O--R.sup.11; [0051]
R.sup.2 is selected from (i) H, (ii) aryl, (iii) C.sub.1 to
C.sub.10 alkyl (iv) arylalkyl, (v) alkylaryl, and (vi)
--(O--C.sub.2H.sub.3R.sup.12).sub.m--OH, [0052] R.sup.3 is selected
from R.sup.1 and R.sup.2; [0053] R.sup.4 is selected from R.sup.2
and, in case R.sup.3 is R.sup.2, R.sup.4 may also be R.sup.1,
[0054] O is a C.sub.6 to C.sub.14 carbocyclic or a C.sub.3 to
C.sub.10 nitrogen or oxygen containing heterocyclic aryl group,
which may be unsubstituted or substituted by up to three C.sub.1 to
C.sub.12 alkyl groups or up to two OH, NH.sub.2 or NO.sub.2 groups,
[0055] R.sup.31 is selected from R.sup.1, H, OR.sup.5 and R.sup.5,
[0056] R.sup.32 is selected from (i) H and (ii) C.sub.1 to C.sub.6
alkyl, [0057] X.sup.1 is a divalent group selected from (i) a
chemical bond (ii) aryl, (iii) C.sub.1 to C.sub.12 alkandiyl, which
may be interrupted by O atoms, (iv) arylalkyl group
--X.sup.11--X.sup.12--, (v) alkylaryl group --X.sup.12--X.sup.11--
and (vi) --(O--C.sub.2H.sub.3R.sup.12).sub.mO--, [0058] X.sup.2 is
(i) a chemical bond or (ii) methanediyl, [0059] R.sup.11 is
selected from H and C.sub.1 to C.sub.4 alkyl, [0060] R.sup.12 is
selected from H and C.sub.1 to C.sub.4 alkyl, [0061] X.sup.12 is a
divalent aryl group, [0062] X.sup.11 is a divalent C.sub.1 to
C.sub.15 alkandiyl group, [0063] A is a co-monomer selected from
vinyl alcohol, which may optionally be (poly)ethyoxylated, and
acrylamide, [0064] B is selected from formula L1a
[0064] ##STR00006## [0065] n is an integer from 2 to 10,000, [0066]
m is an integer from 2 to 50, [0067] o is an integer from 2 to
1000, and [0068] p is 0 or an integer from 1 to 10,000,
[0069] wherein the composition is free of any dispersed
particles.
[0070] The invention further relates to the use of a metal plating
bath comprising a composition as defined herein for depositing
cobalt on substrates comprising recessed features having an
aperture size of 100 nanometers or less, in particular 20 nm or
less, 15 nm or less, or even 7 nm or less.
[0071] The invention further relates to a process for depositing a
layer comprising cobalt on a substrate comprising features having
an aperture size below 100 nm, preferably below 50 nm, by [0072] a)
contacting a composition as defined herein with the substrate, and
[0073] b) applying a current density to the substrate for a time
sufficient to deposit a metal layer onto the substrate.
[0074] In this way additives are provided that result in less
mounding on the wafer above the fully filled recessed features.
DETAILED DESCRIPTION OF THE INVENTION
[0075] The compositions according to the inventions comprise cobalt
ions, and a leveling agent of formulas L1 to L4 as described
below.
[0076] Leveling Agent According to the Invention
[0077] As used herein, "leveling agent" refers to an organic
compound that is, besides any additional functionality, capable of
providing a substantially planar metal layer on the substrate. The
terms "leveler", "leveling agent" and "leveling additive" are used
interchangeably throughout this specification.
[0078] In a first embodiment, the leveling agent to be used in the
electroplating compositions comprises the polymeric structure of
formula L1
[B].sub.n[A].sub.p (L1)
[0079] In a second embodiment the leveling agent to be used in the
electroplating compositions comprises the monomeric structure of
formula L2
##STR00007##
[0080] In a third embodiment the leveling agent to be used in the
electroplating compositions comprises the polymeric structure of
formula L3a or L3b
##STR00008##
[0081] In a fourth embodiment the leveling agent to be used in the
electroplating compositions comprises the monomeric structure of
formula L4
O-R.sup.1 (L4)
[0082] with the substituents described below.
[0083] As used herein, "aryl" means a C.sub.6 to C.sub.14
carbocyclic or a C.sub.3 to C.sub.10 nitrogen or oxygen containing
heterocyclic aromatic ring system, which may be unsubstituted or
substituted by up to three C.sub.1 to C.sub.12 alkyl groups or up
to two OH, NH.sub.2 or NO.sub.2 groups.
[0084] In all embodiments, R.sup.1 in formulas L1 to L4 may be
selected from X.sup.1--CO--O--R.sup.11,
X.sup.1--SO.sub.2--O--R.sup.11, X.sup.1--PO(OR.sup.11).sub.2, and
X.sup.1--SO--OR.sup.11. R.sup.1 is also referred to herein as
"functional group".
[0085] X.sup.1 may be a chemical bond, which means that the
functional groups --CO--O--R.sup.11, --SO.sub.2--O--R.sup.11,
--PO(OR.sup.11).sub.2 and --SO--OR.sup.11 are directly bonded to
the polymer backbone in formula L1, the vinyl group in formula L2
or the aromatic system in formulas L3a, L3b, and L4. As used
herein, "chemical bond" means that the respective moiety is not
present but that the adjacent moieties are bridged so as to form a
direct chemical bond between these adjacent moieties. By way of
example, if in X-Y-Z the moiety Y is a chemical bond then the
adjacent moieties X and Z together form a group X-Z.
[0086] In an alternative X.sup.1 is a divalent aryl group.
Preferred divalent aryl groups are phenylene, naphthalene,
pyridine, or imidazole, particularly 1,4-phenylene.
[0087] In a further alternative X.sup.1 is a divalent C.sub.1 to
C.sub.12 alkanediyl group, which may be interrupted by O atoms. As
used herein, "C.sub.x" means that the respective group comprises x
numbers of C atoms. By way of example, the terms "C.sub.x to
C.sub.y alkanediyl" and C.sub.x to C.sub.y alkyl mean alk(anedi)yl
with a number x to y of carbon atoms and includes linear, branched
(if >C.sub.3) and cyclic alkanediyl (if >C.sub.4).
[0088] In yet a further alternative X.sup.1 is a divalent arylalkyl
group --X.sup.11--X.sup.12--, wherein X.sup.11 is a C.sub.1 to
C.sub.15 alkandiyl group bonded to the polymer backbone, vinyl
group, or aromatic system, respectively, and X.sup.12 is a divalent
aryl group bonded to the functional group. Preferred arylalkyl
groups may be but are not limited to benzyl (ortho, meta or para
form) and 1, 2, or 3-methylpyridine. Preferably the alkanediyl part
X.sup.11 may be methanediyl, propanediyl, or butanediyl. Preferably
the aryl part X.sup.12 may be phenylene, naphthalene, pyridine, or
imidazole, particularly 1,4-phenylene.
[0089] In another alternative X.sup.1 is a divalent alkylaryl group
--X.sup.12--X.sup.11--, wherein X.sup.12 is a divalent aryl group
bonded to the polymer backbone, vinyl group, or aromatic system,
respectively, and X.sup.11 is a C.sub.1 to C.sub.15 alkandiyl group
bonded to the functional group. Preferred arylalkyl groups may be
but are not limited to toluyl (ortho, meta or para form) and 1, 2,
or 3-methylpyridine. Preferably the alkanediyl part X.sup.11 may be
methanediyl, propanediyl, or butanediyl. Preferably the alkanediyl
part X.sup.11 may be phenylene, naphthalene, pyridine, or
imidazole, particularly 1,4-phenylene.
[0090] In yet another alternative X.sup.1 is a divalent
(poly)alkylene oxide spacer --(C.sub.2H.sub.3R.sup.12--O).sub.m--,
wherein R.sup.12 is selected from H and C.sub.1 to C.sub.4 alkyl,
preferably H or methyl, and m is an integer from 1 to 10,
preferably from 1 to 5.
[0091] Preferably, X.sup.1 is selected from a chemical bond,
C.sub.1 to C.sub.4 alkandiyl, and phenylene.
[0092] In a preferred embodiment R.sup.11 is selected from H and
C.sub.1 to C.sub.4 alkyl, preferably H or methyl, most preferably
H.
[0093] In the first embodiment, in formula L1 A is a co-monomeric
unit derived from vinyl alcohol, which may optionally be
(poly)ethyoxylated, or acrylamide, and B is a monomeric unit of
formula L1a
##STR00009##
[0094] Generally, in formulas L1a and L2 of the first and the
second embodiment, R.sup.2, R.sup.3 and R.sup.4 are independently
selected from R.sup.1 and a group R.sup.R with R.sup.R being
selected from [0095] (i) H, [0096] (ii) aryl, preferably a C.sub.6
to C.sub.10 carbocyclic aryl or a C.sub.3 to C.sub.8 heterocyclic
aryl comprising up to two N atoms, most preferably phenyl or
pyridyl, [0097] (iii) C.sub.1 to C.sub.10 alkyl, preferably C.sub.1
to C.sub.6 alkyl, more preferably C.sub.1 to C.sub.4 alkyl, most
preferably C.sub.1 to C.sub.3 alkyl, [0098] (iv) arylalkyl,
preferably a C.sub.7 to C.sub.15 carbocyclic arylalkyl or a C.sub.4
to C.sub.8 heterocyclic arylalkyl comprising up to two N atoms,
more preferably C.sub.4 to C.sub.8 arylalkyl, most preferably
benzyl or 1, 2, or 3-methylpyridine, [0099] (v) alkylaryl,
preferably a C.sub.7 to C.sub.15 carbocyclic alkylaryl or a C.sub.4
to C.sub.8 heterocyclic alkylaryl comprising up to two N atoms,
more preferably C.sub.4 to C.sub.8 alkylaryl, most preferably
toluyl (otho, meta or para form) and 1, 2, or 3-methylpyridine, or
[0100] (vi) a (poly)alkylene oxide substituent
--(O--C.sub.2H.sub.3R.sup.12).sub.m--OH, with m being an integer
from 1 to 50, preferably 1 to 30, more preferably 1 or 2 to 20,
most preferably 1 or 2 to 10, and R.sup.12 being selected from H
and C.sub.1 to C.sup.4 alkyl.
[0101] Since only one of R.sup.2, R.sup.3 and R.sup.4 may comprise
a group R.sup.1 it is required that if one of R.sup.2, R.sup.3 or
R.sup.4 are selected from R.sup.1, the other groups R.sup.2,
R.sup.3 or R.sup.4 are different from R.sup.1.
[0102] In a particular embodiment, in formulas L1a and L2 of the
first and the second embodiment, R.sup.2 is selected from [0103]
(i) H, [0104] (ii) aryl, preferably a C.sub.6 to C.sub.10
carbocyclic aryl or a C.sub.3 to C.sub.8 heterocyclic aryl
comprising up to two N atoms, most preferably phenyl or pyridyl,
[0105] (iii) C.sub.1 to C.sub.10 alkyl, preferably C.sub.1 to
C.sub.6 alkyl, more preferably C.sub.1 to C.sub.4 alkyl, most
preferably C.sub.1 to C.sub.3 alkyl, [0106] (iv) arylalkyl,
preferably a C.sub.7 to C.sub.15 carbocyclic arylalkyl or a C.sub.4
to C.sub.8 heterocyclic arylalkyl comprising up to two N atoms,
more preferably C.sub.4 to C.sub.8 arylalkyl, most preferably
benzyl or 1, 2, or 3-methylpyridine, [0107] (v) alkylaryl,
preferably a C.sub.7 to C.sub.15 carbocyclic alkylaryl or a C.sub.4
to C.sub.8 heterocyclic alkylaryl comprising up to two N atoms,
more preferably C.sub.4 to C.sub.8 alkylaryl, most preferably
toluyl (otho, meta or para form) and 1, 2, or 3-methylpyridine, or
[0108] (vi) a (poly)alkylene oxide substituent
--(O--C.sub.2H.sub.3R.sup.12).sub.m--OH, with m being an integer
from 1 to 50, preferably 1 to 30, more preferably 1 or 2 to 20,
most preferably 1 or 2 to 10, and R.sup.12 being selected from H
and C.sub.1 to C.sup.4 alkyl.
[0109] In a particular embodiment, in formulas L1a and L2, R.sup.3
is selected from R.sup.1 and R.sup.R. R.sup.4 is selected from
R.sup.R and, only in case R.sup.3 is not R.sup.1, R.sup.4 may also
be R.sup.1. In other words: The formulas L1a and L2 may comprise
one or two functional groups R.sup.1. As a consequence, the
levelers of L2 with two functional groups may have cis and trans
configuration with respect to functional group R.sup.1.
[0110] In another particular embodiment, R.sup.2 is selected from
R.sup.1 and R.sup.3 and R.sup.4 are selected from R.sup.R.
[0111] In a preferred embodiment, R.sup.2, R.sup.3 and R.sup.4 are
selected from H, methyl, ethyl, or propyl, most preferably H. In
another preferred embodiment, R.sup.2 and either R.sup.3 or R.sup.4
are selected from H, methyl, ethyl, or propyl, most preferably H
and the other group R.sup.3 or R.sup.4 is selected from R.sup.1. In
another preferred embodiment, R.sup.2 is selected from R.sup.1 and
R.sup.3 and R.sup.4 are selected from H, methyl, ethyl, or propyl,
most preferably H.
[0112] In formula L1, n is an integer from 2 to 10,000 and p may
either be 0 or an integer from 1 to 10,000.
[0113] If p is 0, the levelers of formula L1 may be homopolymers,
such as but not limited to polyacrylic acid, polysulfonic acid,
polyphosphonic acid and the like, in which
R.sup.2.dbd.R.sup.3.dbd.R.sup.4.dbd.H, or polymaleic acid, in which
R.sup.2.dbd.R.sup.4.dbd.H and R.sup.3.dbd.R.sup.1 or
R.sup.2.dbd.R.sup.3.dbd.H and R.sup.4.dbd.R.sup.1, or polyitaconic
acid, in which R.sup.3.dbd.R.sup.4.dbd.H and R.sup.2.dbd.R.sup.1.
Alternatively, the levelers of formula L1 may be co-polymers, such
as but not limited to poly(acrylic acid-co-maleic acid),
poly(acrylic acid-co-itaconic acid), poly(acrylic
acid-co-2-methylacrylic acid), poly(sulfonic acid-co-maleic acid),
poly(sulfonic acid-co-itaconic acid), poly(phosphonic
acid-co-maleic acid), poly(phosphonic acid-co-itaconic acid),
poly(phosphonic acid-co-sulfonic acid), and the like, in order to
tune the sort and the amount of functional groups present in the
leveler.
[0114] Alternatively, if p>0, the polymeric levelers may be
co-polymers of the monomers mentioned above with further monomers
like vinyl alcohol and its ethoxylated or polyethoxylated
derivatives or acrylamide. In this case the sum of n and p is the
overall degree of polymerization.
[0115] The degree of polymerization n+p in formula L1 is preferably
an integer from 2 to 10,000. Most preferably n+p is an integer from
10 to 5000, most preferably from 20 to 5000.
[0116] If copolymers are used, such copolymers may have block,
random, alternating or gradient, preferably random structure. As
used herein, "random" means that the respective co-monomers are
polymerized from a mixture and therefore arranged in a
statistically manner depending on their copolymerization
parameters. As used herein, "block" means that the respective
co-monomers are polymerized after each other to form blocks of the
respective co-monomers in any predefined order.
[0117] The molecular weight M.sub.w of the polymeric levelers of
formula L1 may be from about 500 to about 500000 g/mol, preferably
from about 1000 to about 350000 g/mol, most preferably from about
2000 to about 300000 g/mol. In one particular embodiment the
molecular weight M.sub.w is from about 1500 to about 10000 g/mol.
In another embodiment the molecular weight M.sub.w is from about
15000 to about 50000 g/mol. In yet another embodiment the molecular
weight Mw is from about 100000 to about 300000 g/mol.
[0118] If copolymers are used, the ratio between two monomers B or
the comonomers A and the monomers B in the levelers of formula L1
may be from 5:95 to 95:5% by weight, preferably from 10:90 to
90:10% by weight, most preferably from 20:80 to 80:40% by weight.
Also terpolymers comprising two monomers B and a comonomer A may be
used.
[0119] Particularly preferred polymeric levelers of formula L1 are
polyacrylic acid, polyitaconic acid, a maleic acid acrylic acid
copolymer, an itaconic acid acrylic acid copolymer, an acrylic acid
2-methylacrylic acid copolymer, polyphosphonic acid, and
polysulfonic acid. Most preferred are polyacrylic acid, a maleic
acid acrylic acid copolymer and an acrylic acid 2-methylacrylic
acid copolymer. In case of a maleic acid acrylic acid copolymer or
an itaconic acid acrylic acid copolymer a ratio p:n of 20 80 to
60:40% by weight is particularly preferred. In case of a
2-methylacrylic acid acrylic acid copolymer a ratio p:n of 20 80 to
80:20% by weight is particularly preferred.
[0120] The following specific copolymer levelers of formulas L1b to
L1d are particularly preferred:
##STR00010##
[0121] which is a terpolymer of acrylic acid, maleic acid and
ethyoxylated vinyl alcohol, wherein q and r are integers, the sum
q+r corresponds to p in formula 1 and the ratio q/r is from 10:90
to 90:10, preferably 20:80 to 80:40, most preferably from 40:60 to
60:40; and
##STR00011##
[0122] which is a terpolymer of acrylic acid, maleic acid and
vinylphosponic acid, wherein q and r are integers, the sum q+r
corresponds to p in formula 1 and the ratio q/r is from 10:90 to
90:10, preferably 20:80 to 80:40, most preferably from 40:60 to
60:40.
[0123] Particularly preferred monomeric levelers of formula L2 are
acrylic acid, vinylphosphonic acid, and vinylsulfonic acid.
[0124] In the third embodiment comprising a polymeric leveling
agent of formula L3a or L3b (together also referred to as L3)
R.sup.31 may generally be R.sup.1, H, OR.sup.32 and R.sup.32 as
defined above. Preferably, R.sup.31 is H or OH. Such polymers are
available in the market under Napthalene sulphonic acid
condensation product, Na-salt and Phenol sulfonic acid condensation
product, Na-salt, e.g. from BASF.
[0125] In the levelers of formula L3 X.sup.2 is (i) a chemical bond
or (ii) methanediyl. Preferably X.sup.2 is methanediyl.
[0126] The degree of polymerization o in the levelers of formula L3
is from 2 to 1000.
[0127] Preferably o is an integer from 5 to 500, most preferably
from 10 to 250.
[0128] The molecular weight M.sub.w of the polymeric levelers L3
may be from about 500 to about 400000 g/mol, preferably from about
1000 to about 300000 g/mol, most preferably from about 3000 to
about 250000 g/mol. In one particular embodiment the molecular
weight M.sub.w is from about 1500 to about 10000 g/mol. In another
embodiment the molecular weight M.sub.w is from about 15000 to
about 50000 g/mol. In yet another embodiment the molecular weight
Mw is from about 100000 to about 300000 g/mol.
[0129] In the fourth embodiment, the levelers of formula, L4 O is a
C.sub.6 to C.sub.14 carbocyclic or a C.sub.3 to C.sub.10 nitrogen
or oxygen containing heterocyclic aryl group, which may be
unsubstituted or substituted by up to three C.sub.1 to C.sub.12
alkyl groups or up to two OH, NH.sub.2 or NO.sub.2 groups.
Preferably the heterocyclic aryl groups are 5 or 6 membered rings
systems with up to 2, preferably 1, N atoms.
[0130] Preferred groups O are those of formula L4a
##STR00012##
[0131] wherein R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are
independently selected from (i) H and (ii) C.sub.1 to C.sub.6
alkyl. Preferably R.sup.5, R.sup.6, R.sup.8, and R.sup.9 are
independently selected from H, methyl, ethyl or propyl, most
preferably H. Preferably R.sup.7 is selected from H, methyl, ethyl
or propyl, most preferably from methyl or ethyl.
[0132] In certain embodiments, the leveler may be present in a
concentration between about 1-10,000 ppm, or between about 10-1,000
ppm, or between about 10-500 ppm. In some cases, the concentration
of leveler may be at least about 1 ppm, or at least about 100 ppm.
In these or other cases, the concentration of leveler may be about
500 ppm or less, or about 1000 ppm or less.
[0133] In one embodiment a single leveling agent may be used in the
cobalt electroplating baths, i.e. the bath is essentially free from
any further leveling agent as described in the section below. In
another embodiment two or more of the leveling agents are used in
combination.
[0134] Other Leveling Agents
[0135] The plating composition may further comprise one or more
additional leveling agents.
[0136] Other levelers often contain one or more nitrogen, amine,
imide or imidazole, and may also contain sulfur functional groups.
Certain levelers include one or more five and six member rings
and/or conjugated organic compound derivatives. Nitrogen groups may
form part of the ring structure. In amine-containing levelers, the
amines may be primary, secondary or tertiary alkyl amines.
Furthermore, the amine may be an aryl amine or a heterocyclic
saturated or aromatic amine. Example amines include, but are not
limited to, dialkylamines, trialkylamines, arylalkylamines,
triazoles, imidazole, triazole, tetrazole, benzimidazole,
benzotriazole, piperidine, morpholines, piperazine, pyridine,
oxazole, benzoxazole, pyrimidine, quonoline, and isoquinoline.
Imidazole and pyridine may be useful in some cases. Other examples
of levelers include Janus Green B and Prussian Blue. Leveler
compounds may also include ethoxide groups. For example, the
leveler may include a general backbone similar to that found in
polyethylene glycol or polyethylene oxide, with fragments of amine
functionally inserted over the chain (e.g., Janus Green B). Example
epoxides include, but are not limited to, epihalohydrins such as
epichlorohydrin and epibromohydrin, and polyepoxide compounds.
Polyepoxide compounds having two or more epoxide moieties joined
together by an ether-containing linkage may be useful in some
cases. Some leveler compounds are polymeric, while others are not.
Example polymeric leveler compounds include, but are not limited
to, polyethylenimine, polyamidoamines, and reaction products of an
amine with various oxygen epoxides or sulfides. One example of a
non-polymeric leveler is 6-mercapto-hexanol. Another example
leveler is polyvinylpyrrolidone (PVP).
[0137] Example levelers that may be particularly useful in the
context of cobalt deposition in combination with the leveler
according to the subject invention include, but are not limited to:
alkylated polyalkyleneimines; polyethylene glycol; organic
sulfonates; 4-mercaptopyridine; 2-mercaptothiazoline; ethylene
thiourea; thiourea; 1-(2-hydroxyethyl)-2-imidazolidinethion; sodium
naphthalene 2-sulphonate; acrylamide; substituted amines;
imidazole; triazole; tetrazole; piperidine; morpholine; piperazine;
pyridine; oxazole; benzoxazole; quinolin; isoquinoline; coumarin
and derivatives thereof.
[0138] Suppressing Agents
[0139] The plating composition may further comprise, and preferably
comprises, one or more suppressing agents. Particularly if the
semiconductor substrate to be electroplated comprises recessed
features having an aperture size below 100 nm, particularly below
50 nm, even more particular if the aspect ratio of the recessed
features is 4 or more, the use of a suppressing agent is usually
required.
[0140] As used herein, "suppressing agent" refers to an organic
compound that decreases the plating rate of the electroplating bath
on at least part of a substrate. In particular, a suppressor is an
additive that suppresses the plating rate on the substrate above
any recessed features. Dependent on the diffusion and adsorption
the suppressor decreases the plating rate at the upper sidewalls of
the recessed features. The terms "suppressor" and "suppressing
agent" are used interchangeably throughout this specification.
[0141] As used herein, "feature" refers to the cavities on a
substrate, such as, but not limited to, trenches and vias.
"Apertures" refer to recessed features, such as vias and trenches.
As used herein, the term "plating" refers to metal electroplating,
unless the context clearly indicates otherwise. "Deposition" and
"plating" are used interchangeably throughout this
specification.
[0142] "Aperture size" according to the present invention means the
smallest diameter or free distance of a recessed feature before
plating, i.e. after seed deposition. The terms "width", "diameter",
"aperture" and "opening" are used herein, depending on the geometry
of the feature (trench, via, etc.) synonymously.
[0143] As used herein, "aspect ratio" means the ratio of the depth
to the aperture size of the recessed feature.
[0144] Without limitation, typical suppressing agents are selected
from the group consisting of: carboxymethylcellulose,
nonylphenolpolyglycol ether, polyethylene glycoldimethyl ether,
octandiolbis(polyalkylene glycol ether), octanol polyalkylene
glycol ether, oleic acid polyglycol ester, polyethylene propylene
glycol, polyethylene glycol, polyethylene-imine, polyethylene
glycoldimethyl ether, polyoxypropylene glycol, polypropylene
glycol, polyvinyl alcohol, stearic acid polyglycol ester, stearyl
alcohol polyglycol ether, polyethylene oxide, ethylene
oxide-propylene oxide copolymers, butyl alcohol-ethylene
oxide-propylene oxide copolymers,
2-Mercapto-5-benzimidazolesulfonic acid, 2-mercaptobenzimidazole
(MBI), benzotriazole, and combinations thereof.
[0145] In some embodiments, the suppressor includes one or more
nitrogen atoms such as an amine group or an imine group. In some
embodiments, the suppressor is a polymeric or oligomeric compound
containing amine groups separated by a carbon aliphatic spacer such
as CH.sub.2CH.sub.2 or CH.sub.2CH.sub.2CH.sub.2. In a particular
embodiment, the suppressor is polyethyleneimine (PEI, also known as
polyaziridine, poly[imino(1,2-ethanediyl)], or
poly(iminoethylene)). PEI has shown very good bottom-up fill
characteristics in the context of cobalt deposition, as shown in
the experimental results included herein.
[0146] Particularly preferred suppressing agents are those of
formula S1
##STR00013##
[0147] to fill aperture sizes having nanometer or micrometer scale,
in particular aperture sizes having 100 nanometers or less, 20 nm
or less, 15 nm or less or even 7 nm or less.
[0148] Herein, R.sup.1 is selected from X-Y, wherein X is a
divalent spacer group selected from linear or branched C.sub.1 to
C.sub.10 alkanediyl, linear or branched C.sub.2 to C.sub.10
alkenediyl, linear or branched C.sub.2 to C.sub.10 alkynediyl, and
(C.sub.2H.sub.3R.sup.6--O).sub.m. m is an integer selected from 1
to 30, preferably from 1 to 15, even more preferably from 1 to 10,
most preferably from 1 to 5.
[0149] In a preferred embodiment X is selected from linear or
branched C.sub.1 to C.sub.6 alkanediyl, preferably from C.sub.1 to
C.sub.4 alkanediyl.
[0150] In a preferred embodiment X is selected from methanediyl,
ethane-1,1-diyl and ethane-1,2-diyl. In a second preferred
embodiment X is selected from propan-1,1-diyl, butane-1,1-diyl,
pentane-1,1-diyl, and hexane-1,1-diyl. In a third preferred
embodiment X is selected from propane-2-2-diyl, butane-2,2-diyl,
pentane-2,2-diyl, and hexane-2,2-diyl. In a fourth preferred
embodiment X is selected from propane-1-2-diyl, butane-1,2-diyl,
pentane-1,2-diyl, and hexane-1,2-diyl. In a fifth preferred
embodiment X is selected from propane-1-3-diyl, butane-1,3-diyl,
pentane-1,3-diyl, and hexane-1,3-diyl.
[0151] Y is a monovalent group and may be selected from OR.sup.3,
with R.sup.3 being selected from (i) H, (ii) C.sub.5 to C.sub.20
aryl, preferably C.sub.5, C.sub.6, and C.sub.10 aryl, (iii) C.sub.1
to C.sub.10 alkyl, preferably C.sub.1 to C.sub.6 alkyl, most
preferably C.sub.1 to C.sub.4 alkyl, (iv) C.sub.6 to C.sub.20
arylalkyl, preferably C.sub.6 to C.sub.10 arylalkyl, (v) C.sub.6 to
C.sub.20 alkylaryl, all of which may be substituted by OH,
SO.sub.3H, COOH or a combination thereof, and (vi)
(C.sub.2H.sub.3R.sup.6--O).sub.m--H. In a preferred embodiment,
R.sup.3 may be C.sub.1 to C.sub.6 alkyl or H. R.sup.6 may be
selected from H and C.sub.1 to C.sub.5 alkyl, preferably from H and
C.sub.1 to C.sub.4 alkyl, most preferably H, methyl or ethyl.
[0152] In another preferred embodiment, R.sup.3 is selected from H
to form a hydroxy group. In another preferred embodiment, R.sup.3
is selected from polyoxyalkylene groups of formula
(C.sub.2H.sub.3R.sup.6--O).sub.m--H. R.sup.6 is selected from H and
C.sub.1 to C.sub.5 alkyl, preferably from H and C.sub.1 to C.sub.4
alkyl, most preferably from H, methyl or ethyl. Generally, n may be
an integer from 1 to 30, preferably from 1 to 15, most preferably
from 1 to 10. In a particular embodiment polyoxymethylene,
polyoxypropylene or a polyoxymethylene-co-oxypropylene may be used.
In another preferred embodiment, R.sup.3 may be selected from
C.sub.1 to C.sub.10 alkyl, preferably from C.sub.1 to C.sub.6
alkyl, most preferably methyl and ethyl.
[0153] Furthermore, Y may be an amine group NR.sup.3R.sup.4,
wherein R.sup.3 and R.sup.4 are the same or different and may have
the meanings of R.sup.3 described for OR.sup.3 above.
[0154] In a preferred embodiment, R.sup.3 and R.sup.4 are selected
from H to form an NH.sub.2 group. In another preferred embodiment,
at least one of R.sup.3 and R.sup.4, preferably both are selected
from polyoxyalkylene groups of formula
(C.sub.2H.sub.3R.sup.6--O).sub.m--H. R.sup.6 is selected from H and
C.sub.1 to C.sub.5 alkyl, preferably from H and C.sub.1 to C.sub.4
alkyl, most preferably H, methyl or ethyl. In yet another preferred
embodiment, at least one of R.sup.3 and R.sup.4, preferably both
are selected from C.sub.1 to C.sub.10 alkyl, preferably from
C.sub.1 to C.sub.6 alkyl, most preferably methyl and ethyl.
[0155] R.sup.3 and R.sup.4 may also together form a ring system,
which may be interrupted by O or NR.sup.7. R.sup.7 may be selected
from R.sup.6 and
##STR00014##
Such ring system may preferably comprise 4 or 5 carbon atoms to
form a 5 or 6 membered carbocyclic system. In such carbocyclic
system one or two of the carbon atoms may be substituted by oxygen
atoms.
[0156] Furthermore, Y may be a positively charged ammonium group
N.sup.+R.sup.3R.sup.4R.sup.5. R.sup.3, R.sup.4, R.sup.5 are the
same or different and may have the meanings of R.sup.3 described
for OR.sup.3 and NR.sup.3R.sup.4 above. In a preferred embodiment
R.sup.3, R.sup.4 and R.sup.5 are independently selected from H,
methyl or ethyl.
[0157] m may be an integer selected from 1 to 30, preferably from 1
to 15, even more preferably from 1 to 10, most preferably from 1 to
5.
[0158] In the additives of formula S1 R.sup.2 may be either
selected from R.sup.1 or R.sup.3 as described above. If R.sup.2 is
R.sup.1, R.sup.1 may be selected to form a symmetric compound (both
R.sup.1s are the same) or an asymmetric compound (the two R.sup.1s
are different).
[0159] In a preferred embodiment R.sup.2 is H.
[0160] Particularly preferred aminoalkynes are those in which
[0161] (a) R.sup.1 is X--NR.sup.3R.sup.4 and R.sup.2 is H; [0162]
(b) R.sup.1 is X--NR.sup.3R.sup.4 and R.sup.2 is X--NR.sup.3R.sup.4
with X being selected from linear C.sub.1 to C.sub.4 alkanediyl and
branched C.sub.3 to C.sub.6 alkanediyl;
[0163] Particularly preferred hydroxyalkynes or alkoxyalkynes are
those in which [0164] (a) R.sup.1 is X--OR.sup.3 and R.sup.2 is H;
[0165] (b) R.sup.1 is X--OR.sup.3 and R.sup.2 is X--OR.sup.3 with X
being selected from linear C.sub.1 to C.sub.4 alkanediyl and
branched C.sub.3 to C.sub.6 alkanediyl;
[0166] Particularly preferred alkynes comprising an amino and a
hydroxy group are those in which R.sup.1 is X--OR.sup.3,
particularly X--OH, and R.sup.2 is X--NR.sup.3R.sup.4 with X being
independently selected from linear C.sub.1 to C.sub.4 alkanediyl
and branched C.sub.3 to C.sub.6 alkanediyl;
[0167] The amine groups in the additives may be selected from
primary (R.sup.3, R.sup.4 is H) , secondary (R.sup.3 or R.sup.4 is
H) and tertiary amine groups (R.sup.3 and R.sup.4 are both not
H).
[0168] The alkynes may comprise one or more terminal triple bonds
or one or more non-terminal triple bonds (alkyne functionalities).
Preferably, the alkynes comprise one or more terminal triple bonds,
particularly from 1 to 3 triple bonds, most preferably one terminal
triple bond.
[0169] Particularly preferred specific primary aminoalkynes
are:
##STR00015##
[0170] Particularly preferred specific secondary aminoalkynes
are:
##STR00016##
[0171] Particularly preferred specific tertiary aminoalkynes
are:
##STR00017##
[0172] Other preferred additives are those in which the rests
R.sup.3 and R.sup.4 may together form a ring system, which is
optionally interrupted by O or NR.sup.3. Preferably, the rests
R.sup.3 and R.sup.4 together form a C.sub.5 or C.sub.6 bivalent
group in which one or two, preferably one, carbon atoms may be
exchanged by O or NR.sup.7, with R.sup.7 being selected from
hydrogen, methyl or ethyl.
[0173] An example of such compounds is:
##STR00018##
[0174] The first one may be received by reaction of propargyl amine
with formaldehyde and morpholine, the second and third ones by
reaction of propargyl alcohol with formaldehyde and piperidine or
morpholine, respectively.
[0175] Another preferred additive comprising a saturated
heterocyclic system is:
##STR00019##
[0176] In this case R.sup.3 and R.sup.4 together form a ring system
which is interrupted by two NR.sup.3 groups, in which R.sup.3 is
selected from CH.sub.2--C.ident.C--H. This additive comprises three
terminal triple bonds.
[0177] The amino groups in the additives may further be quaternized
by reaction with alkylating agents such as but not limited to
dialkyl sulphates like DMS, DES or DPS, benzyl chloride or
chlormethylpyridine. Particularly preferred quaternized additives
are:
##STR00020##
[0178] Particularly preferred specific pure hydroxyalkynes are:
##STR00021##
[0179] Particularly preferred specific aminoalkynes comprising OH
groups are:
##STR00022##
[0180] Also in this case the rests R.sup.3 and R.sup.4 may together
form a ring system, which is optionally interrupted by O or
NR.sup.3. Preferably, the rests R.sup.3 and R.sup.4 together form a
C.sub.5 or C.sub.6 bivalent group in which one or two, preferably
one, carbon atoms may be exchanged by O or NR.sup.7, with R.sup.7
being selected from hydrogen, methyl or ethyl.
[0181] Examples for such compounds are:
##STR00023##
[0182] These may be received by reaction of propargyl alcohol with
formaldehyde and piperidine or morpholine, respectively.
[0183] By partial reaction with alkylating agents mixtures of
additives may be formed. In one embodiment, such mixtures may be
received by reaction of 1 mole diethylaminopropyne and 0.5 mole
epichlorohydrin, 1 mole diethylaminopropyne and 0.5 mole
benzylchloride, 1 mole diethylaminopropyne with 0.9 mole dimethyl
sulphate, 1 mole dimethyl propyne amine and 0.33 mole dimethyl
sulphate, or 1 mole dimethyl propyne amine and 0.66 mole dimethyl
sulphate. In another embodiment such mixtures may be received by
reaction of 1 mole dimethyl propyne amine and 1.5, 1.9, or 2.85
mole dimethyl sulphate, 1 mole dimethyl propyne amine and 0.5 mole
epichlorohydrin, 1 mole dimethyl propyne amine and 2.85 diethyl
sulphate, or 1 mole dimethyl propyne amine and 1.9 mole dipropyl
sulphate.
[0184] In a further embodiment, the suppressing agents may be
substituted by SO.sub.3H (sulfonate) groups or COOH (carboxy)
groups. Specific sulfonated additives may be but are not limited to
butynoxy ethane sulfonic acid, propynoxy ethane sulfonic acid,
1,4-di-(.beta.-sulfoethoxy)-2-butyne,
3-(.beta.-sulfoethoxy)-propyne.
[0185] In general, the total amount of the suppressing agents in
the electroplating bath is from 0.5 ppm to 10000 ppm based on the
total weight of the plating bath. The suppressing agents are
typically used in a total amount of from about 0.1 ppm to about
1000 ppm based on the total weight of the plating bath and more
typically from 1 to 100 ppm, although greater or lesser amounts may
be used. Preferred concentration ranges are for example between
about 10-60 ppm, or between about 15-60 ppm, or between about 30-60
ppm. In this context, parts per million (ppm) is a mass fraction of
the suppressor molecules in the electrolyte. In some cases, the
suppressor may have a concentration of at least about 10 ppm, or at
least about 15 ppm, or at least about 20 ppm, or at least about 30
ppm, or at least about 50 ppm. In these or other cases, the
suppressor may have a concentration of about 1,000 ppm or less, for
example about 500 ppm or less, about 100 ppm or less, about 75 ppm
or less, about 60 ppm or less, or about 50 ppm or less.
[0186] Other Additives
[0187] A large variety of further additives may typically be used
in the bath to provide desired surface finishes for the Co plated
metal. Usually more than one additive is used with each additive
forming a desired function. Advantageously, the electroplating
baths may contain one or more of wetting agents or surfactants like
Lutensol.RTM., Plurafac.RTM. or Pluronic.RTM. (available from BASF)
to get rid of trapped air or hydrogen bubbles and the like. Further
components to be added are grain refiners, stress reducers,
levelers and mixtures thereof.
[0188] The bath may also contain a complexing agent for the cobalt
ions, such as but not limited to sodium acetate, sodium citrate,
EDTA, sodium tartrate, or ethylene diamine.
[0189] Further additives are disclosed in Journal of The
Electrochemical Society, 156 (8) D301-D309 2009 "Superconformal
Electrodeposition of Co and Co--Fe Alloys Using
2-Mercapto-5-benzimidazolesulfonic Acid", which is incorporated
herein by reference.
[0190] In a further embodiment, surfactants may be present in the
electroplating composition in order to improve wetting. Wetting
agents may be selected from nonionic surfactants, anionic
surfactants and cationic surfactants.
[0191] In a preferred embodiment non-ionic surfactants are used.
Typical non-ionic surfactants are fluorinated surfactants,
polyglocols, or poly oxyethylene and/or oxypropylene containing
molecules.
[0192] Electrolyte
[0193] In one embodiment, the usually aqueous plating bath used for
void-free filling with cobalt may contain a cobalt ion source, such
as but not limited to cobalt sulfate, cobalt chloride, or cobalt
sulfamate. Preferably the metal ions essentially consist of cobalt
ions. As used herein, "consisting essentially of cobalt ions" means
a content of other metal ions less than 1% by weight, preferably
less than 0.1% by weight, more preferably less than 0.01% by
weight. Most preferably the electrodeposition composition is free
of any metal ions except cobalt ions.
[0194] The cobalt ion concentration within the electroplating
solution may be in a range of 0.01 to 1 mol/l. In one particular
example, the ion concentration can have a range of 0.1 to 0.6
mol/l. In another particular example, the range can be from 0.3 to
0.5 mol/l. In yet another particular example, the range can be from
0.03 to 0.1 mol/l.
[0195] In a preferred embodiment the composition is essentially
free of chloride ions. Essentially free from chloride means that
the chloride content is below 1 ppm, particularly below 0.1
ppm.
[0196] During deposition, the pH of the plating bath may be
adjusted to have a high Faradaic efficiency while avoiding the
co-deposition of cobalt hydroxides. For this purpose, a pH range of
1 to 5 may be employed. In a particular example pH range of 2 to
4.5 can be employed. In another particular example, a pH range of 3
to 4 can be used. Preferably the pH is below 5, most preferably
below 4.
[0197] In a preferred embodiment boric acid may be used in the
cobalt electroplating bath as supporting electrolyte. Boric acid
may be incorporated into the composition in a concentration between
about 5 and about 50 g/l, such as between about 15 and about 40
g/l.
[0198] In another preferred embodiment the cobalt electrodeposition
composition comprises an ammonium compound. The ammonium compound
is added to the electrolyte in form of different types of ammonium
compounds like ammonium sulfate, ammonium chloride, ammonium
methane sulfonate as described in unpublished European patent
application No. 18168249.3.
[0199] Generally the ammonium compound is described by formula
(NR.sup.B1R.sup.B2R.sup.B3H.sup.+).sub.nX.sup.n-.
[0200] Herein, R.sup.B1, R.sup.B2, and R.sup.B3 are independently
selected from H, linear or branched C.sub.1 to C.sub.6 alkyl.
Preferably, R.sup.1, R.sup.2, and R.sup.3 are independently
selected from H and a linear or branched C.sub.1 to C.sub.4 alkyl,
particularly methyl and ethyl. More preferably at least one of
R.sup.B1, R.sup.B2, and R.sup.B3 is H, even more preferably at
least two of R.sup.B1, R.sup.B2, and R.sup.B3 are H. Most
preferably, R.sup.B1, R.sup.B2, and R.sup.B3 are H.
[0201] X is an n valent inorganic or organic counter ion. Typical
inorganic counter-ions are, without limitation, chloride, sulfate
(including hydrogen sulfate), phosphate (including hydrogen and
dihydrogen phosphate), and nitrate. Typical organic counter-ions
are, without limitation, C.sub.1 to C.sub.6 alkyl sulfonate,
preferably methane sulfonate, C.sub.1 to C.sub.6 carboxylates,
preferably acetate or citrate, phosponate, sulfamate, etc.
Inorganic counter-ions are preferred. Chloride is the most
preferred counter ions X since by using chloride in combination
with the ammonium cation the non-uniformity of the cobalt deposit
across the wafer may be further improved.
[0202] n is an integer selected from 1, 2 or 3 depending on the
valence of the counter-ion. By way of example, for chloride and
hydrogen sulfate n would be 1, for sulfate or hydrogen phosphate n
would be 2 and for phosphate n would be 3.
[0203] Depending on the pH of the composition the amine compound
may be completely or partly protonated or deprotonated.
[0204] Preferably the cobalt or electroplating composition is
essentially free of boric acid. Essentially free of boric acid as
used herein means a boric acid content below 0.1 g/l, preferably
below 100 ppm by mass, most preferably the content of boric acid is
below the detection limit.
[0205] The electrodeposition composition is preferably free of zinc
ions, nickel ions and iron ions. If either nickel ions or iron ions
are present, the molar ratio of both nickel ions and iron ions, and
the sum of zinc ions, nickel ions and iron ions, to cobalt ions is
preferably not greater than about 0.01, or between about 0.00001
and about 0.01.
[0206] The electrodeposition composition is also preferably
substantially free of copper ions. Although very minor copper
contamination may be difficult to avoid, it is particularly
preferred that the copper ion content of the bath is no more than
20 ppb, e.g., in the range of 0.1 ppb to 20 ppb.
[0207] The electrodeposition composition is preferably free of any
functional concentration of reducing agents effective to reduce
cobaltous ion (Co.sup.2+) to metallic cobalt (Co.sup.0). By a
functional concentration is meant any concentration of an agent
that either is effective to reduce cobaltous ions in the absence of
electrolytic current or is activated by an electrolytic current or
electrolytic field to react with cobaltous ions.
[0208] The electrodeposition composition is essentially free of
dispersed particles, preferably free of particles. "Essentially
free of dispersed particles" means that there are no macroscopic
particulate solids in the solution that are dispersed and therefore
negatively interfere with the metal electroplating process. Any
particles that are deposited and not dispersed during storage of
the bath or during the electroplating process do usually not
interfere with the metal electroplating.
[0209] The electrodeposition composition is preferably a
homogeneous composition. As used herein, "homogeneous" means that
the composition is a solution of the components in a liquid that is
essentially free of any particles, particularly free of any
dispersed particles.
[0210] Process
[0211] An electrolytic bath is prepared comprising cobalt ions and
at least one additive according to the invention. A dielectric
substrate having the seed layer is placed into the electrolytic
bath where the electrolytic bath contacts the at least one outer
surface and the three dimensional pattern having a seed layer in
the case of a dielectric substrate. A counter electrode is placed
into the electrolytic bath and an electrical current is passed
through the electrolytic bath between the seed layer on the
substrate and the counter electrode. At least a portion of cobalt
is deposited into at least a portion of the three dimensional
pattern wherein the deposited cobalt is substantially
void-free.
[0212] The present invention is useful for depositing a layer
comprising cobalt on a variety of substrates, particularly those
having nanometer and variously sized apertures. For example, the
present invention is particularly suitable for depositing cobalt on
integrated circuit substrates, such as semiconductor devices, with
small diameter vias, trenches or other apertures. In one
embodiment, semiconductor devices are plated according to the
present invention. Such semiconductor devices include, but are not
limited to, wafers used in the manufacture of integrated
circuits.
[0213] In order to allow a deposition on a substrate comprising a
dielectric surface a seed layer needs to be applied to the surface.
Such seed layer may consist of cobalt, iridium, osmium, palladium,
platinum, rhodium, and ruthenium or alloys comprising such metals.
Preferred is the deposition on a cobalt seed. The seed layers are
described in detail e.g. in US20140183738 A.
[0214] The seed layer may be deposited or grown by chemical vapor
deposition (CVD). atomic layer deposition (ALD), physical vapor
deposition (PVD). Electroplating, electro less plating or other
suitable process that deposits conformal thin films. In an
embodiment, the cobalt seed layer is deposited to form a high
quality conformal layer that sufficiently and evenly covers all
exposed surfaces within the openings and top Surfaces. The high
quality seed layer may be formed, in one embodiment. by depositing
the cobalt seed material at a slow deposition rate to evenly and
consistently deposit the conformal seed layer. By forming the seed
layer in a conformal manner, compatibility of a subsequently formed
fill material with the underlying structure may be improved.
Specifically, the seed layer can assist a deposition process by
providing appropriate surface energetics for deposition
thereon.
[0215] Preferably the substrate comprises submicrometer sized
features and the cobalt deposition is performed to fill the
submicrometer sized features. Most preferably the
submicrometer-sized features have an (effective) aperture size of
10 nm or below and/or an aspect ratio of 4 or more. More preferably
the features have an aperture size of 7 nanometers or below, most
preferably of 5 nanometers or below.
[0216] The electrodeposition current density should be chosen to
promote the void-free, particularly the bottom-up filling behavior.
A range of 0.1 to 40 mA/cm.sup.2 is useful for this purpose. In a
particular example, the current density can range from 1 to 10
mA/cm.sup.2. In another particular example, the current density can
range from 5 to 15 mA/cm.sup.2.
[0217] The general requirements for a process of cobalt
electrodeposition on semiconductor integrated circuit substrates is
described in US 2011/0163449 A1.
[0218] Typically, substrates are electroplated by contacting the
substrate with the plating baths of the present invention. The
substrate typically functions as the cathode. The plating bath
contains an anode, which may be soluble or insoluble. Optionally,
cathode and anode may be separated by a membrane. Potential is
typically applied to the cathode. Sufficient current density is
applied and plating performed for a period of time sufficient to
deposit a metal layer, such as a cobalt layer, having a desired
thickness on the substrate. Suitable current densities include, but
are not limited to, the range of 1 to 250 mA/cm.sup.2. Typically,
the current density is in the range of 1 to 60 mA/cm.sup.2 when
used to deposit cobalt in the manufacture of integrated circuits.
The specific current density depends on the substrate to be plated,
the leveling agent selected and the like. Such current density
choice is within the abilities of those skilled in the art. The
applied current may be a direct current (DC), a pulse current (PC),
a pulse reverse current (PRC) or other suitable current.
[0219] In general, when the present invention is used to deposit
metal on a substrate such as a wafer used in the manufacture of an
integrated circuit, the plating baths are agitated during use. Any
suitable agitation method may be used with the present invention
and such methods are well-known in the art. Suitable agitation
methods include, but are not limited to, inert gas or air sparging,
work piece agitation, impingement and the like. Such methods are
known to those skilled in the art. When the present invention is
used to plate an integrated circuit substrate, such as a wafer, the
wafer may be rotated such as from 1 to 300 RPM and the plating
solution contacts the rotating wafer, such as by pumping or
spraying. In the alternative, the wafer need not be rotated where
the flow of the plating bath is sufficient to provide the desired
metal deposit.
[0220] Cobalt is deposited in apertures according to the present
invention without substantially forming voids within the metal
deposit.
[0221] As used herein, void-free fill may either be ensured by an
extraordinarily pronounced bottom-up cobalt growth while perfectly
suppressing the sidewall cobalt growth, both leading to a flat
growth front and thus providing substantially defect free
trench/via fill (so-called bottom-up-fill) or may be ensured by a
so-called V-shaped filling.
[0222] As used herein, the term "substantially void-free", means
that at least 95% of the plated apertures are void-free. Preferably
that at least 98% of the plated apertures are void-free, mostly
preferably all plated apertures are void-free. As used herein, the
term "substantially seam-free", means that at least 95% of the
plated apertures are void-free. Preferably that at least 98% of the
plated apertures are seam-free, mostly preferably all plated
apertures are seam-free.
[0223] Plating equipment for plating semiconductor substrates are
well known. Plating equipment comprises an electroplating tank
which holds Co electrolyte and which is made of a suitable material
such as plastic or other material inert to the electrolytic plating
solution. The tank may be cylindrical, especially for wafer
plating. A cathode is horizontally disposed at the upper part of
tank and may be any type substrate such as a silicon wafer having
openings such as trenches and vias. The wafer substrate is
typically coated with a seed layer of Co or other metal or a metal
containing layer to initiate plating thereon. An anode is also
preferably circular for wafer plating and is horizontally disposed
at the lower part of tank forming a space between the anode and
cathode. The anode is typically a soluble anode.
[0224] These bath additives are useful in combination with membrane
technology being developed by various tool manufacturers. In this
system, the anode may be isolated from the organic bath additives
by a membrane. The purpose of the separation of the anode and the
organic bath additives is to minimize the oxidation of the organic
bath additives.
[0225] The cathode substrate and anode are electrically connected
by wiring and, respectively, to a rectifier (power supply). The
cathode substrate for direct or pulse current has a net negative
charge so that Co ions in the solution are reduced at the cathode
substrate forming plated Co metal on the cathode surface. An
oxidation reaction takes place at the anode. The cathode and anode
may be horizontally or vertically disposed in the tank.
[0226] While the process of the present invention has been
generally described with reference to semiconductor manufacture, it
will be appreciated that the present invention may be useful in any
electrolytic process where a substantially void-free cobalt deposit
is desired. Such processes include printed wiring board
manufacture. For example, the present plating baths may be useful
for the plating of vias, pads or traces on a printed wiring board,
as well as for bump plating on wafers. Other suitable processes
include packaging and interconnect manufacture. Accordingly,
suitable substrates include lead frames, interconnects, printed
wiring boards, and the like.
[0227] All percent, ppm or comparable values refer to the weight
with respect to the total weight of the respective composition
except where otherwise indicated. All cited documents are
incorporated herein by reference.
[0228] The following examples shall further illustrate the present
invention without restricting the scope of this invention.
EXAMPLES
[0229] A. Example Levelers [0230] Leveler 1: Copolymer of acrylic
acid and maleic acid having a (mass average) molecular weight
M.sub.w of 3,000 g/mol and an MA content of 50% by weight. [0231]
Leveler 2: Copolymer of acrylic acid and methylacrylic acid having
a molecular weight M.sub.w of 20,000 g/mol and an MA content of
70%by weight. [0232] Leveler 3: Polyacrylic acid having a molecular
weight M.sub.w of 2,500 g/mol [0233] Leveler 4: Polyacrylic acid
having a molecular weight M.sub.w of 250,000 g/mol [0234] Leveler
5: Sodium p-Toluol sulfonate
[0234] ##STR00024## [0235] Leveler 6: Vinylphosphonic acid [0236]
Leveler 7: Polyvinylphosphonic acid having a molecular weight
M.sub.w of 2,310 g/mol [0237] Leveler 8: Polyvinylsulfonic acid
having a molecular weight M.sub.w of 250,000 g/mol.
[0238] These compounds are available in the market.
[0239] B. Plating Experiments
Example 1 (Comparative)
[0240] Plating was done using a potentiostat setup, immersing the
wafer coupon pieces in an electrolyte bath opposite a blank Co
anode. The electrolyte was an aqueous Co sulfate-based solution
comprised of 3 g/L cobalt, 33 g/L boric acid, and water. The
electrolyte was adjusted to a pH of 2.75 with 1 M H.sub.2SO.sub.4.
An alkynole type suppressor at a concentration of 72 ppm was used.
The electrolyte was maintained at 25.degree. C. with a pH of 2.75.
Patterned wafer coupons, each piece including trench features of
various dimensions of 40 nm, 50 nm, 85 nm, and 120 nm (pitch: 1:1),
were immersed in the electrolyte solution at -1V potentiostatic
entry for 0.5 s before galvanostatic control was enabled.
Galvanostatic plating then proceeded in a two-step process: Step 1
with an applied current density of 2 mA/cm.sup.2 for 200 s wherein
the wafer coupon cathode was rotated at 100 rpm, and Step 2 with an
applied current density of 10mA/cm.sup.2 for 110 s wherein the
wafer coupon was rotated at 25 rpm. The plating conditions were
selected for optimal fill with a suppressor-only bath, and plating
was done with baths incorporating both suppressor only and
suppressor and leveller combined.
[0241] Measurements of bump height were completed by profilometry
and measured against a reference point over an unpatterned wafer
area. The results are summarized in Table 1 and depicted in FIG. 1.
FIG. 1 shows a cobalt deposition which fails in the desired
leveling. This can be clearly seen from the bump formation of more
than 200 nm over the dense features.
Examples 2 to 9
[0242] Example 1 was repeated but the respective Leveler was added
to the plating bath at a concentration specified in Table 1.
[0243] The results are summarized in Table 1. Table 1 shows that
the cobalt deposition provides the desired levelling behavior. This
can particularly be seen by a reduced bump formation particularly
over the dense features of 40 and 50 nm width when adding the
respective leveler.
TABLE-US-00001 TABLE 1 L dose 40 nm 1:1 50 nm 1:1 85 nm 1:1 120 nm
1:1 Example Leveler [ppm] pitch [nm] pitch [nm] pitch [nm] pitch
[nm] 1 none 0 237 231 185 208 2 Leveler 1 0.9 113 123 101 57 3
Leveler 2 9 58 119 117 83 4 Leveler 3 0.9 24 22 39 5 5 Leveler 4
0.9 45 54 38 24 6 Leveler 5 0.09 119 121 150 114 7 Leveler 6 85 102
63 46 129 8 Leveler 7 9 93 104 90 59 9 Leveler 8 450 104 40 44
22
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