U.S. patent application number 14/132983 was filed with the patent office on 2014-04-17 for composition and method for polishing aluminum semiconductor substrates.
The applicant listed for this patent is Cabot Microelectronics Corporation. Invention is credited to Ji CUI, Steven GRUMBINE, Chih-An LIN, Glenn WHITENER.
Application Number | 20140103250 14/132983 |
Document ID | / |
Family ID | 47881054 |
Filed Date | 2014-04-17 |
United States Patent
Application |
20140103250 |
Kind Code |
A1 |
CUI; Ji ; et al. |
April 17, 2014 |
COMPOSITION AND METHOD FOR POLISHING ALUMINUM SEMICONDUCTOR
SUBSTRATES
Abstract
The invention provides a chemical-mechanical polishing
composition comprising coated .alpha.-alumina particles, an organic
carboxylic acid, and water. The invention also provides a
chemical-mechanical polishing composition comprising an abrasive
having a negative zeta potential in the polishing composition, an
organic carboxylic acid, at least one alkyls disulfonate
surfactant, and water, wherein the polishing composition does not
further comprise a heterocyclic compound. The abrasive is
colloidally stable in the polishing composition. The invention
further provides methods of polishing a substrate with the
aforesaid polishing compositions.
Inventors: |
CUI; Ji; (Aurora, IL)
; GRUMBINE; Steven; (Aurora, IL) ; WHITENER;
Glenn; (Batavia, IL) ; LIN; Chih-An; (New
Taipei City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cabot Microelectronics Corporation |
Aurora |
IL |
US |
|
|
Family ID: |
47881054 |
Appl. No.: |
14/132983 |
Filed: |
December 18, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13237881 |
Sep 20, 2011 |
8623766 |
|
|
14132983 |
|
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Current U.S.
Class: |
252/79.1 |
Current CPC
Class: |
C09K 3/1463 20130101;
C09K 3/1436 20130101; C09G 1/02 20130101; H01L 21/3212
20130101 |
Class at
Publication: |
252/79.1 |
International
Class: |
C09G 1/02 20060101
C09G001/02 |
Claims
1. A chemical-mechanical polishing composition comprising: (a)
.alpha.-alumina particles coated with a copolymer consisting
essentially of at least one sulfonate monomer and at least one
acrylate monomer, (b) an organic carboxylic acid, and (c) water,
wherein the polishing composition has a pH of about 1 to about 6,
and wherein the abrasive is colloidally stable in the polishing
composition.
2. The composition of claim 1, wherein the copolymer comprises
about 50 mole % to about 90 mole % of the acrylate monomer and
about 10 mole % to about 50 mole % of the sulfonate monomer.
3. The composition of claim 1, wherein the composition further
comprises an agent that oxidizes a metal.
4. The composition of claim 1, wherein the composition further
comprises a surfactant.
5. The composition of claim 4, wherein the surfactant is an
alkyldiphenyloxide disulfonate surfactant.
6. A chemical-mechanical polishing composition comprising: (a) an
abrasive, wherein the abrasive comprises particles having a
negative zeta potential in the polishing composition, (b) organic
carboxylic acid, (c) at least one alkyldiphenyloxide disulfonate
surfactant, and (d) water, wherein the polishing composition has a
pH of about 1 to about 6, wherein the abrasive is colloidally
stable in the polishing composition, and wherein the polishing
composition does not comprise a heterocyclic compound.
7. The composition of claim 6, wherein the abrasive is unmodified
wet process silica or wet process silica modified with anionic
functional groups.
8. The composition of claim 6, wherein the abrasive comprises
.alpha.-alumina particles coated with a copolymer consisting
essentially of at least one sulfonate monomer and at least one
acrylate monomer.
9. The composition of claim 6, wherein the complexing agent for
aluminum comprises an organic carboxylic acid.
10. The composition of claim 9, wherein the organic carboxylic acid
is selected from the group consisting of malonic acid, phthalic
acid, lactic acid, tartaric acid, gluconic acid, citric acid, malic
acid, glycolic acid, maleic acid, and combinations thereof.
11. The composition of claim 6, wherein the polishing composition
further comprises an agent that oxidizes aluminum.
Description
BACKGROUND OF THE INVENTION
[0001] Integrated circuits are made up of millions of active
devices formed in or on a substrate, such as a silicon water. In
one manufacturing process, a dielectric substrate is patterned by a
conventional dry etch process to form holes and trenches for
vertical and horizontal interconnects. The patterned surface is
then optionally coated with a diffusion barrier layer and/or an
adhesion-promoting layer, followed by deposition of a metal layer
to fill the trenches and holes. Chemical-mechanical polishing (CMP)
is employed to reduce the thickness of the metal layer, as well as
the thickness of the diffusion barrier layer and/or
adhesion-promoting layer, until the underlying dielectric layer is
exposed, thereby forming the circuit device.
[0002] One way to fabricate planar metal circuit traces on a
silicon dioxide substrate is referred to as the damascene process.
In accordance with this process, the silicon dioxide dielectric
surface having optionally a layer of silicon nitride deposited
thereon is patterned by applying a photoresist, exposing the
photoresist to irradiation through a pattern to define trenches
and/or vias, and then using a conventional dry etch process to form
holes and trenches for vertical and horizontal interconnects. The
silicon nitride functions as a "hard mask" to protect the silicon
dioxide surface that is not part of the trenches and/or vias from
damage during etching. The patterned surface is coated with an
adhesion-promoting layer such as titanium or tantalum and/or a
diffusion barrier layer such as titanium nitride or tantalum
nitride. The adhesion-promoting layer and/or the diffusion barrier
layer are then over-coated with a metal layer. Chemical-mechanical
polishing is employed to reduce the thickness of the metal
over-layer, as well as the thickness of any adhesion-promoting
layer and/or diffusion barrier layer, until a planar surface that
exposes elevated portions of the silicon oxide surface is obtained.
The vias and trenches remain filled with electrically conductive
metal forming the circuit interconnects.
[0003] Tungsten and copper are most frequently used as the
electrically conductive metal. However, aluminum, which had been
used in earlier generation processes to fabricate circuit
interconnects via subtractive processes such as etching techniques,
has been under increasing consideration for use in damascene
processes. The combination of aluminum and titanium offers
potentially lower resistivity than other metal/barrier layer
combinations, with corresponding potential improvement in circuit
performance.
[0004] Polishing compositions for aluminum damascene structures
comprising alumina abrasives treated with sulfonate-containing
polymers or copolymers have been described. While the
sulfonate-containing polymers or copolymers are intended to confer
colloidal stability to the alumina abrasives, the presence of other
polishing components such as complexing agents, topography control
agents, and surface treatment polymers can result in displacement
of the sulfonate-containing polymers or copolymers from the alumina
abrasive particles, with the result that colloidal stability of the
polishing compositions is compromised. Interparticle agglomeration
leading to large particles can lead to scratching and other surface
defects on substrates being polished. Thus, there remains a need in
the art for improved methods of polishing aluminum-containing
substrates.
BRIEF SUMMARY OF THE INVENTION
[0005] The invention provides a method of chemically-mechanically
polishing a substrate, which method comprises (i) providing a
substrate comprising at least one layer of aluminum, (ii) providing
a polishing pad, (iii) providing a polishing composition comprising
(a) .alpha.-alumina particles coated with a copolymer comprising at
least one sulfonate monomer and at least one monomer selected from
the group consisting of carboxylate monomers, phosphonate monomers,
and phosphate monomers, (b) a complexing agent for aluminum and (c)
water, (iv) contacting a surface of the substrate with the
polishing pad and the polishing composition, and (v) abrading at
least a portion of the surface of the substrate to remove at least
some aluminum from the surface of the substrate and to polish the
surface of the substrate, wherein the polishing composition has a
pH of about 1 to about 6, and wherein the abrasive is colloidally
stable in the polishing composition.
[0006] The invention also provides a method of
chemically-mechanically polishing a substrate, which method
comprises (i) providing a substrate comprising at least one layer
of aluminum, (ii) providing a polishing pad, (iii) providing a
polishing composition comprising (a) an abrasive, wherein the
abrasive comprises particles having a negative zeta potential in
the polishing composition, (b) complexing agent for aluminum, (c)
at least one alkyldiphenyloxide disulfonate surfactant, and (c)
water, (iv) contacting a surface of the substrate with the
polishing pad and die polishing composition, and (v) abrading at
least a portion of the surface of the substrate to remove at least
some aluminum from the surface of the substrate and to polish the
surface of the substrate, wherein the polishing composition has a
pH of about 1 to about 6, and wherein the abrasive is colloidally
stable in the polishing composition,
[0007] The invention further provides a chemical-mechanical
polishing composition comprising (a) .alpha.-alumina particles
coated with a copolymer consisting essentially of least one
sulfonate monomer and at least one acrylate monomer, (b) an organic
carboxylic acid and (c) water, wherein the polishing composition
has a pH of about 1 to about 6, and wherein the abrasive is
colloidally stable in the polishing composition.
[0008] The invention additionally provides a chemical-mechanical
polishing composition comprising (a) an abrasive, wherein the
abrasive comprises particles having a negative zeta potential in
the polishing composition, (b) an organic carboxylic acid, (c) at
least One alkyldiphenyloxide disulfonate surfactant, and (d) water,
wherein the polishing composition has a pH of about 1 to about 6,
wherein the abrasive is colloidally stable in the polishing
composition, and wherein the polishing composition does not
comprise a compound of the formula: (X.sup.2).sub.n-L wherein
X.sup.2 represents tetrazole. 1,2,4-triazole, 1,2,3-triazole, or
benzotriazole, and wherein L represents a linking group.
DETAILED DESCRIPTION OF THE INVENTION
[0009] The invention provides a method of chemically-mechanically
polishing as substrate, which method comprises (i) providing a
substrate comprising at least one layer of aluminum, (ii) providing
a polishing pad, (iii) providing a polishing; composition, (iv)
contacting a surface of the substrate with the polishing pad and
the polishing composition, and (v) abrading at least a portion of
the surface of the substrate to remove at least some aluminum from
the surface of the substrate and to polish the surface of the
substrate. The polishing composition comprises (a) .alpha.-alumina
particles coated with a copolymer comprising at least one sulfonate
monomer and at least one monomer selected from the group consisting
of carboxylate monomers, phosphonate monomers, and phosphate
monomers, (b) as complexing agent for aluminum, and (c) water.
Alternatively, the polishing, composition comprises (a) an
abrasive, wherein the abrasive comprises particles having a
negative zeta potential in the polishing composition, (b) a
complexing agent for aluminum) at least one alkyldiphenyloxide
disulfonate surfactant, and (c) water. In both situations, the
polishing composition has a pH of about 1 to about 6, and the
abrasive is colloidally stable in the polishing composition.
[0010] The abrasive can be any suitable abrasive, for example, the
abrasive can be natural or synthetic, and can comprise metal oxide,
carbide, nitride, carborundum, and the like. The abrasive also can
be a polymer particle or a coated particle. The abrasive desirably
comprises, consists essentially of, or consists of a metal oxide.
In a preferred embodiment, the metal oxide is alumina. The alumina
can comprise, consist essentially of, or consist of any suitable
phase of alumina, for example, .alpha.-alumina, .gamma.-alumina,
.delta.-alumina, fumed alumina, and combinations thereof. Most
preferably, the metal oxide comprises, consists essentially of or
consists of .alpha.-alumina. When the abrasive comprises
.alpha.-alumina, the abrasive also can comprise other forms of
alumina, such as fumed alumina. In some embodiments, the abrasive
consists of .alpha.-alumina.
[0011] The abrasive can have any suitable average particle size
average particle diameter). In particular, and especially when the
abrasive is alumina, the abrasive can have an average particle size
(e.g., average particle diameter) of about 15 nm or more (e.g.,
about 20 nm or more, about 30 nm or more, or about 40 nm or more,
or about 50 nm or more, or about 75 nm or more). Alternatively, or
in addition, the abrasive can have an average particle size of
about 250 nm or less (e.g., about 200 nm or less, or about 150 nm
or less, or about 125 nm or less, or about 100 nm or less). Thus,
the abrasive can have an average particle size bounded by any two
of the above endpoints. For example, the abrasive can have an
average particle size of about 15 nm to about 250 nm, about 20 nm
to about 200 nm, about 30 nm about 200 nm, about 30 nm to about 150
nm, about 40 nm to about 250 nm, about 40 nm about 200 nm, about 40
nm to about 150 nm, about 50 nm to about 250 nm, about 50 nm to
about 200 nm, or about 50 nm to about 150 nm. In this regard,
particle size refers to the diameter of the smallest sphere that
encompasses the particle.
[0012] In an embodiment, the abrasive particles are treated with a
copolymer comprising at least one sulfonate monomer and at least
one monomer selected from the group consisting of carboxylate
monomers, phosphonate monomers, and phosphate monomers. In a
preferred embodiment, the copolymer comprises a combination or at
least one sulfonate monomer and at least one carboxylate monomer.
Preferably, the sulfonate monomer is selected from the group
consisting of vinyl sulfonic acid,
2-(methacryloyloxy)ethanesulfonic acid, styrene sulfonic acid,
2-acrylamido-2-methylpropane sulfonic acid. Preferably, the other
monomer is selected from the group consisting of acrylic acid,
methacrylic acid, itaconic acid, maleic acid, maleic anhydride,
vinylphosphonic acid, 2-(methacroyloxy)ethylphosphate, and
combinations thereof. More preferably, the other monomer comprises
at least one carboxylate monomer and most preferably comprises at
least one acrylate monomer. In particular embodiments the copolymer
is selected from the group consisting of polyacrylic
acid-co-polyacrylamido-2-methylpropane sulfonic acid, polyacrylic
acid-co-polystyrenesulfonic acid, and polyvinylphosphonic
acid-co-polyarylamido-2-methylpropane sulfonic acid.
[0013] In another embodiment, the abrasive particles are treated
with a negatively-charged polymer or copolymer. The
negatively-charged polymer or copolymer can be any suitable polymer
or copolymer. The negatively-charged polymer or copolymer
preferably comprises at least one sulfonate monomer which is
different than the copolymer comprising at least one sulfonate
monomer and at least one monomer selected from the group consisting
of carboxylate monomers, phosphonate monomers, and phosphate
monomers. Preferably, the negatively-charged polymer or copolymer
comprises repeating units selected from the group consisting of
vinyl sulfonic acid, 2-(methacryloyloxy)ethanesulfonic acid,
styrene sulfonic acid, 2-actylamido-2-methylpropane sulfonic acid,
and combinations thereof. Most preferably, the negatively-charged
polymer or copolymer is selected from the group consisting of
poly(2-acrylamido-2-methylpropane sulfonic acid) and
polystyrenesulfonic acid.
[0014] The abrasive particles can be separately treated with a
polymer or copolymer prior to addition to the polishing
composition. Any suitable method can be used to treat the abrasive
particles with the polymer or copolymer. For example, the abrasive
particles can be treated with the polymer or copolymer under high
shear conditions using, for example, a Waring blender. In other
embodiments, the abrasive particles can be treated with the polymer
or copolymer in situ during preparation of the polishing
composition. The polymer or copolymer can be added at any time
during the preparation of the polishing composition, either before
the addition of the abrasive particles, simultaneously with the
abrasive particles, or after addition of the abrasive particles,
with one or more of the other components of the polishing
composition added or present at any suitable time.
[0015] Desirably, the abrasive comprises, consists essentially of,
or consists of abrasive particles that have a negative zeta
potential at the pH of the polishing composition. In some
embodiments, the abrasive particles, when untreated, can have a
positive zeta potential at the pH of the polishing composition, but
have a negative zeta potential at the pH of the polishing
composition upon treatment with a polymer or copolymer as described
herein. In other embodiments, the abrasive can be an untreated
abrasive having a negative zeta potential at the pH of the
polishing composition. Non-limiting examples of abrasives
comprising particles having a negative zeta potential at the pH of
the polishing composition include wet-process silica and fumed
silica. The zeta potential of a particle refers to the difference
between the electrical charge of the ions surrounding the particle
and the electrical charge of the bulk solution (e.g., the liquid
carrier and arty other components dissolved therein).
[0016] The polishing composition comprises a complexing agent for
aluminum. The complexing agent for aluminum can be any suitable
complexing agent. Preferably, the complexing agent for aluminum is
an organic carboxylic acid. More preferably, the complexing agent
for aluminum is selected from the group consisting of malonic acid,
phthalic acid, lactic acid, tartaric acid, gluconic acid, citric
acid, malic acid, glycolic acid, maleic acid, and combinations
thereof.
[0017] The polishing composition can comprise any suitable amount
of the complexing agent for aluminum. The polishing composition can
contain about 0.1 wt. % or more, e.g., about 0.2 wt. % or more,
about 0.3 wt. % or more, about 0.4 wt. % or more, or about 0.5 wt.
% or more of the complexing agent for aluminum. Alternatively, or
in addition, the polishing composition can contain about 3 wt. % or
less, e.g., about 2.5 wt. % or less. about 2 wt. % or less, about
1.5 wt. % or less, or about 1 wt. % or less of the complexing agent
for aluminum. Thus, the polishing composition can comprise the
complexing agent for aluminum in an amount bounded by any two of
the above endpoints recited for the abrasive particles. For example
the polishing composition can comprise about 0.1 wt. % to about 3
wt. %, about 0.1 wt. % to about 2.5 wt. %, about 0.1 wt. % to about
2 wt. %, about 0.3 wt% to about 3 wt. %, about 0.3 wt. % to about
2.5 wt. %, about 0.3 wt. % to about 2 wt. %, about 0.5 wt. % to
about 3 wt. %, about 0.5 wt. % to about 2.5 wt. %, or about 0.5 wt.
% to about 2 wt. % of the complexing agent for aluminum.
[0018] The abrasive desirably is suspended in the polishing
composition, more specifically in the water of the polishing
composition. When the abrasive is suspended in the polishing
composition, the abrasive preferably is colloidally stable. The
term colloid refers to the suspension of abrasive particles in the
water. Colloidal stability refers to the maintenance of that
suspension over time. In the context of this invention, an abrasive
is considered colloidally stable if, when a suspension of the
abrasive in water or in the polishing composition is placed into a
100 ml graduated cylinder and allowed to stand unagitated for a
time of 2 hours (e.g., for a time of 4 hours, or for a time of 8
hours, or for a time of 24 hours, or for a time of one week, or for
a time of 4 weeks, or for a time of 16 weeks), the difference
between the concentration of particles in the bottom 50 ml of the
graduated cylinder ([B] in terms of g/ml) and the concentration of
particles in the top 50 ml of the graduated cylinder ([T] in terms
of g/ml) divided by the initial concentration of particles in the
abrasive composition ([C] in terms of g/ml) is less than or equal
to 0.5 (i.e., {[B]-[T]}/[C].ltoreq.0.5). The value of [B]-[T]/[C]
desirably is less than or equal to 0.3, and preferably is less than
or equal to 0.1.
[0019] The polishing composition optionally further comprises an
agent that oxidizes aluminum. The agent that oxidizes aluminum can
be any agent having a suitable oxidation potential at the pH of the
polishing composition. Non-limiting examples of suitable oxidizing
agents include oxidizing agents selected from the group consisting
of hydrogen peroxide, organic peroxy acids, persulfate, nitrate,
periodate, perbromate, bromate, ferric salts, and combinations
thereof.
[0020] The polishing composition can comprise any suitable amount
of the agent that oxidizes aluminum. The polishing composition can
contain about 0.1 wt. % or more, e.g., about 0.25 wt. % or more,
about 0.5 wt. % or more, about 0.75 wt. % or more, or about 1 wt. %
or more of the agent that oxidizes aluminum. Alternatively, or in
addition, the polishing composition can contain about 5 wt. % or
less, e.g., about 4 wt. % or less, about 3 wt. % or less, about 2
wt. % or less, or about 1 wt. % or less of the agent that oxidizes
aluminum. Thus, the polishing composition can comprise the agent
that oxidizes aluminum in an amount bounded by any two of the above
endpoints recited for the abrasive particles. For example the
polishing composition can comprise about 0.1 wt. % to about 5 wt.
%, about 0.25 wt. % to about 4 wt. %, about 0.5 wt. % to about 3
wt. %. about 0.75 wt. % to about 2 wt. %, about 1 wt. % to about 3
wt. %, or about 1 wt. % to about 2 wt. % of the agent that oxidizes
aluminum.
[0021] The polishing composition optionally further comprises a
surfactant. The surfactant can be an anionic, non-ionic, or a
zwitterionic surfactant. Advantageously, the presence of the
surfactant in the polishing composition improves the colloidal
stability of the polishing composition, stabilizes the particle
size of abrasive particles, and/or improves the topography of
semiconductor waters that are polished with the polishing
composition. Non-limiting examples of suitable surfactants include
polysulfonates, polycarboxylates, polyphosphonates, polyalcohols
polyvinyl alcohols), copolymers comprising monomers selected from
the group consisting of sulfonates, carboxylates, phosphonates,
alcohols, and combinations thereof.
[0022] In a preferred embodiment, the surfactant is an
alkyldiphenyloxide sulfonate surfactant. Typically, the
alkyldiphenyloxide sulfonate surfactant has the structure:
##STR00001##
wherein R is a C.sub.1-C.sub.30, preferably C.sub.6-C.sub.30, more
preferably C.sub.6-C.sub.22 linear or branched, saturated or
unsaturated alkyl group, wherein the alkyl group optionally
contains one or more heteroatoms selected from the group consisting
of O and N, and wherein X.sup.+ or a cation, e.g., an alkali metal
cation or alkaline earth cation (e.g., sodium, potassium, lithium,
calcium, magnesium, and the like). Examples of suitable
alkyldiphenyloxide sultanate surfactants include surfactants
commercially available from the Dow Chemical Company (Midland,
Mich.) under the trade names Dowfax.TM. 2A1, Dowfax.TM. 382,
Dowfax.TM. 8390, Dowfax.TM. C6L, Dowfax.TM. C10L, and Dowfax.TM.
30599.
[0023] The polishing composition can contain any suitable amount of
the surfactant. Thus, the polishing composition can contain 0.001
wt. % or more, e.g., about 0.005 wt. % or more, about 0.01 wt. % or
more, about 0.05 wt. % or more, about 0.1 wt. % or more, about 0.2
wt. % or more, about 0.3 wt. % or more, about 0.4 wt. % or more, or
about 0.5 wt. % or more of the surfactant. Alternatively, or in
addition. the polishing composition can contain about 2 wt. % or
less, e.g., about 1.8 wt. % or less, about 1.6 wt. % or less, about
1.4 wt. % or less. about 1.2 wt. % or less, or about 1 wt. % or
less of the surfactant. Thus, the polishing composition can
comprise the surfactant in an amount bounded by any two of the
above endpoints recited for the surfactant. For example the
polishing composition can comprise about 0.001 wt. % to about 2 wt.
%, about 0.05 wt. % to about 1.8 wt. %, about 0.1 wt. % to about
1.6 wt. %, about 0.2 wt. % to about 1.4 wt. %, about 0.3 wt. % to
about 1.2 wt. %, about 0.4 wt. % to about: 1.2 wt. %, or about 0.5
wt. % to about 1 wt. % of the surfactant.
[0024] Desirably, the polishing composition does not comprise a
compound of the formula: (X.sup.2).sub.n-L wherein X represents
tetrazole, 1,2,3-triazole, or benzotriazole, wherein L represents a
linking f.troup, for example, wherein L represents a linking group
having a valence of 2 or more which contains at least one group
selected from the group consisting of midi) groups, thioureido
groups, amide groups, ester groups, sulfonamide groups,
sulfonureido groups, hydroxy groups, carbamate groups, ether
groups, amino groups, carboxy groups, sulfa groups, and
heterocyclic groups, and n is an integer of 2 or more.
[0025] Desirably, the polishing composition will have a pH of about
1 or more (e.g., about 2 or more). Preferably, the polishing
composition will have a pH of about 5 or less (e.g., about 4 or
less, or about 3 or less). More preferably, the polishing
composition will have a pH of about 2 to about 4 (e.g., about 2 to
about 3).
[0026] The pH of the polishing composition can be achieved and/or
maintained by any suitable means. More specifically, the polishing,
composition can further comprise a pH adjustor, a pH buffering
agent, or a combination thereof. The pH adjustor can be any
suitable pH-adjusting compound. For example, the pH adjustor can be
nitric acid, potassium hydroxide, ammonium hydroxide, or
combinations thereof. The pH buffering agent can be any suitable
buffering, agent, for example, phosphates, sulfates, acetates,
borates, ammonium salts, and the like. The polishing composition
can comprise any suitable amount of a pH adjustor and/or a pH
buffering agent, provided that a suitable amount of the buffering
agent is used to achieve and/or maintain the pH of the polishing
composition within the ranges set forth herein.
[0027] The polishing composition optionally comprises a
film-forming agent (i.e., a corrosion inhibitor). The film-forming
agent can be any suitable film-forming agent for any component(s)
of the substrate. Preferably, the film-forming agent is a
copper-corrosion inhibitor or a tungsten-corrosion inhibitor. For
the purposes of this invention, a film-forming agent is any
compound, or mixture of compounds, that facilitates the formation
of a passivation layer (i.e., a dissolution-inhibiting layer) on at
least a portion of the surface being polished. Useful film-forming
agents include, for example, nitrogen-containing heterocyclic
compounds. The film-forming agent desirably comprises one or more
5- or 6-membered, heterocyclic, nitrogen-containing rings.
Preferred film-forming agent include 1,2,3-triazole,
1,2,4-triazole, benzotriazole, benzimidazole, benzothiazole, and
derivatives thereof, such as, for example, hydroxy-, amino-,
imino-, carboxy-, mercapto-, nitro-, urea-, thiourea-, or
alkyl-substituted derivatives thereof. Most preferably, the
film-forming agent is selected from the group consisting of
benzotriazole, 1,2,4-triazole, and mixtures thereof.
[0028] The polishing composition can contain any suitable amount of
the film-forming agent. Thus, the polishing composition can contain
0.0001 wt. % or more, e.g., about 0.0005 wt. % or more, about 0.001
wt. % or more, about 0.005 wt. % or more, about 0.01 wt. % or more,
or about 0.1 wt. % or more of the film-forming agent.
Alternatively, or in addition, the polishing composition can
contain about 2 wt. % or less, e.g., about 1.8 wt. % or less, about
1.6 wt. % or less, about 1.4 wt. % or less, about 1.2 wt. % or
less, or about 1 wt. % or less of the film-forming agent. Thus, the
polishing composition can comprise the film-forming agent in an
amount bounded by any two of the above endpoints recited for the
film-forming agent. For example the polishing composition can
comprise about 0,0001 wt. % to about 2 wt. %, about 0.005 wt. % to
about 1.8 wt. %, about 0.01 wt % to about 1.6 wt %, or about 0.1
wt. % to about 1 wt. % of the film-forming agent.
[0029] The polishing composition optionally further comprises a
biocide. The biocide can be any suitable biocide, for example, an
isothiazolinone biocide. The amount of biocide used in the
polishing composition typically is about 1 ppm to about 500 ppm,
and preferably is about 10 ppm to about 200 ppm.
[0030] The polishing composition can be prepared by any suitable
technique, many of which are known to those skilled in the art. The
polishing composition can be prepared in a batch or continuous
process. Generally, the polishing composition can be prepared by
combining the components thereof in any order. The term "component"
as used herein includes individual ingredients (e.g., abrasive,
complexing agent for aluminum, agent that oxidizes aluminum,
surfactant, optional film-forming agent, optional biocide, etc.) as
well as any combination of ingredients (e.g., abrasive, complexing
agent for aluminum, agent that oxidizes aluminum, surfactant,
optional film-forming agent, optional biocide, etc.).
[0031] For example, the abrasive can be dispersed in water. The
complexing agent for aluminum, optional surfactant, optional
film-forming agent, and optional biocide can then be added, and
mixed by any method that is capable of incorporating the components
into the polishing composition. The agent that oxidizes aluminum,
if utilized, can be added at any time during the preparation of the
polishing composition. The polishing composition can be prepared
prior to use, with one or more components, such as the agent that
oxidizes aluminum, added to the polishing composition just before
use (e.g., within about 1 minute before use, or within about 1 hour
before use, or within about 7 days before use). The polishing
composition also can be prepared by mixing the components at the
surface of the substrate during the polishing operation.
[0032] The polishing composition can be supplied as a one-package
system comprising abrasive, complexing agent for aluminum, agent
that oxidizes aluminum, surfactant, optional film-forming agent,
optional biocide, and water. Alternatively, the abrasive can be
supplied as a dispersion in water in a first container, and
complexing agent for aluminum, surfactant, optional film-forming
agent, and optional biocide can be supplied in a second container,
either in dry form, or as a solution or dispersion in water. The
agent that oxidizes aluminum desirably is supplied separately from
the other components of the polishing composition and is combined,
e.g., by the end-user, with the other components of the polishing
composition shortly before use (e.g., 1 week or less prior to use,
1 day or less prior to use, 1 hour or less prior to use, 10
minute's or less prior to use, or 1 minute or less prior to use).
The components in the first or second container can be in dry form
while the components in the other container can be in the form of
an aqueous dispersion. Moreover, it is suitable for the components
in the first and second containers to have different pH values, or
alternatively to have substantially similar, or even equal, pH
values. Other two-container, or three or more-container,
combinations of the components of the polishing composition are
within the knowledge of one of ordinary skill in the art.
[0033] The polishing composition of the invention also can be
provided as a concentrate which is intended to be diluted with an
appropriate amount of water prior to use. In such an embodiment,
the polishing composition concentrate can comprise the abrasive,
complexing agent for aluminum, surfactant, optional film-forming
agent, optional biocide, and water, with or without the optional
agent that oxidizes aluminum, in amounts such that, upon dilution
of the concentrate with an appropriate amount of water, and the
optional agent that oxidizes aluminum if not already present in an
appropriate amount, each component of the polishing composition
will be present in the polishing composition in an amount within
the appropriate range recited above for each component. For
example, the abrasive, complexing agent for aluminum, surfactant,
optional film-forming agent, and optional biocide can each be
present in the concentration in amount that is about 2 times (e.g.,
about 3 times, about 4 times, or about 5 times) greater than the
concentration recited above for each component so that, when the
concentrate is diluted with an equal volume of (e.g., 2 equal
volumes of water, 3 equal volumes of water, or 4 equal volumes of
water, respectively), along with the optional agent that oxidizes
aluminum in a suitable amount, each component will be present in
the polishing, composition in an amount within the ranges set forth
above for each component. Furthermore, as be understood by those of
ordinary skill in the art, the concentrate can contain an
appropriate fraction of the water present in the final polishing
composition in order to ensure that other components are at least
partially or fully dissolved in the concentrate.
EXAMPLES
[0034] The following examples further illustrate the invention but,
of course, should not be construed as in any way limiting its
scope.
[0035] In the following examples, the polishing experiments were
conducted using a three-platen Mirra polisher (Applied Materials;
Santa Clara, Calif.). The polishing parameters were as follows:
Polishing was conducted on platen 1 in two phases: phase 1 at 24.2
kPa downforce, phase 2 at 13.8 kPa downforce using a D100 polishing
pad (Cabot Microelectronics Corporation, Aurora, Ill.). Platen 2
was used for buff cleaning. The substrates consisted of
titanium-lined patterned silicon dioxide-coated silicon wafers
overcoated with aluminum. The substrates comprised a pattern
comprising 10 .mu.m lines separated by 10 .mu.m spacings.
Example 1
[0036] This example demonstrates the improvement in defectivity
achievable by the polishing, compositions of the invention, when
used to polish substrates comprising aluminum deposited on
titanium-lined features on a dielectric layer.
[0037] Two substrates were separately polished with two different
polishing compositions. Composition 1A and Composition 1B. Each of
the polishing compositions contained 1.5 wt. % of lactic acid and 3
wt. % of hydrogen peroxide in water at a pH of 3.4. Composition 1A
(comparative) further contained 0.5 wt. % of .alpha.-alumina
treated with about 1150 ppm of polyacrylainino-2-methylpropane
sulfonic acid. Composition 1B (invention) further contained 0.5 wt.
% of .alpha.-alumina treated with about 1150 ppm of polyacrylic
acid-co-polyacrylamido-2-methylpropane sulfonic acid. Composition
1C (comparative) further contained 0.5 wt. % of .alpha.-alumina
treated with about 1150 ppm of polyacrylic acid. Composition 1C was
not colloidally stable and therefore was not used in polishing
substrates.
[0038] Following polishing, the substrates were cleaned, and the
defectivity was inspected by an AIT wafer inspection system
(KLA-Tencor; Milpitas, Calif.). Normalized total defects were
determined as the ratio of scanned images to total number of images
multiplied by the defect count. The results are set forth in Table
1.
TABLE-US-00001 TABLE 1 Sulfonate Molecular Weight Monomer of
Polymer or Normalized Composition (molar %) Copolymer Total Defects
1A (comparative) 100 20000 100 1B (inventive) 20 30000 21 1C
(comparative) 0 50000 NA
[0039] As is apparent from the results set forth in Table 1, the
use of Composition 1B, which contained .alpha.-alumina treated with
polyacrylic acid-co-polyacrylamido-2-methylpropane sulfonic acid,
resulted in approximately 20% of the normalized total defects as
observed with the use of Composition 1A, which contained
.alpha.-alumina treated with polyacrylamino-2-methylpropane
sulfonic acid. Composition 1B was colloidally stable for at least 6
months, while Composition 1A maintained colloidal stability for 7
to 60 days.
Example 2
[0040] This example demonstrates the improvement in defectivity
achievable by the polishing compositions of the invention, when
used to polish substrates comprising aluminum deposited on
titanium-lined features on a dielectric layer.
[0041] Five substrates were separately polished with five different
polishing compositions. Compositions 2A-2E. Each of the polishing
compositions contained about 1 wt. % of lactic acid, about 3 wt. %
of hydrogen peroxide, and 1000 ppm of Dowfax.TM. 8390 (an
alkyldiphenyloxide sulfonate surfactant) in water at a pH of 3.4.
Composition 2A (comparative) further contained 0.5 wt. % of
.alpha.-alumina treated with about 1150 ppm of
polyacrylamino-2-methylpropane sulfonic acid. Compositions 2B-2E
(inventive) further contained 0.5 wt. % of .alpha.-alumina treated
with about 1150 ppm of polyacrylic
acid-co-polyacrylamido-2-methylpropane sulfonic acid copolymers
having varying molar percentages of sulfonate-containing monomers
and having varying molecular weights as set forth in Table 2.
[0042] Following polishing, the substrates were cleaned, and the
defectivity was inspected by an AIT wafer inspection system. Total
scratch defects were determined as the number of images with
scratches as observed by the AIT system. The results are set forth
in Table 2.
TABLE-US-00002 TABLE 2 Sulfonate Monomer Total Scratch Composition
(molar %) Molecular Weight Defects 2A (comparative) 100 20000 2227
2B (inventive) 25 30000 33 2C (inventive) 20 21000 43 2D
(inventive) 17 24000 34 2E (inventive) 14 7400 47
[0043] As is apparent from the results set forth in Table 2, the
use of Compositions 2B-2E, all of which contained .alpha.-alumina
treated with polyacrylic acid-co-polyacrylamido-2-methylpropane
sulfonic acid copolymers, resulted in approximately 1.5% to
approxiimitely 2.1% of total scratch defects as compared with the
use of Composition 2A, which contained .alpha.-alumina treated with
polyacrylamino-2-methylpropane sulfonic acid.
Example 3
[0044] This example demonstrates the improvement in defectivity
achievable by the polishing compositions of the invention, when
used to polish substrates comprising aluminum deposited cm
titanium-lined features on a dielectric layer.
[0045] Three substrates were separately polished with three
different polishing compositions. Compositions 3A-3C. Each of the
polishing compositions contained about 1 wt. % of lactic acid and
about 3 wt. % of hydrogen peroxide in water at a pH of 3.4.
Composition 3A (comparative) further contained 0.5 wt. % of
.alpha.-alumina treated with about 1150 ppm of
polyacrylamino-2-methylpropane sulfonic acid and 1000 ppm of a
polycarboxylic acid polymer having a molecular weight of 100,000.
Composition 3B (invention) further contained 0.5 wt. % of
.alpha.-alumina treated with about 1150 ppm of
polyacrylamino-2-methylpropane sulfonic acid and 1000 ppm of
Dowfax.TM. 8390 (an alkyldiphenyloxide sulfonate surfactant).
Composition 3C (invention) further contained 0.5 wt. % of
.alpha.-alumina treated with about 1150 ppm of
polyacrylic-co-polyacrylamido-2-methylpropane sulfonic acid but did
not further contain any additional polymer or copolymer. The
treated .alpha.-alumina abrasives had a negative zeta potential in
the polishing compositions.
[0046] Following polishing, the substrates were cleaned. The amount
of aluminum dishing was measured, and the defectivity was inspected
by an AIT wafer inspection system. Total scratch defects were
determined as the number of images with scratches as observed by
the AIT system. The results are set forth in Table 3.
TABLE-US-00003 TABLE 3 Total Scratch Composition Additive Dishing
(.ANG.) Defects 3A (comparative) Polycarboxylic acid 61 19000 3B
(inventive) Dowfax .TM. 8390 42 1600 3C (inventive) None 209
475
[0047] As is apparent from the results set forth in Table 3, the
use of Composition 3B, which contained 1000 ppm of an
alkyldiphenyloxide sulfonate surfactant (i.e., Dowfax.TM. 8390),
resulted in approximately 8.4% of total scratch defects as compared
with the use of Composition 3A, which contained 1000 ppm of a
polycarboxylic acid polymer. The use of Composition 3C, which
contained .alpha.-alumina treated with about 1150 ppm of
polyacrylic-co-polyacrylamido-2-methylpropane sulfonic acid but did
not further contain any additional copolymer, resulted in
approximately 2.5% and approximately 30% of total scratch detects
as compared with use of Compositions 3A and 3B, respectively.
However, the use of Composition 3C resulted in dishing which was
approximately 5 times greater than observed with the use of
Composition 3B.
Example 4
[0048] This example demonstrates the improvement in defectivity
achievable by the polishing compositions of the invention, when
used to polish substrates comprising aluminum deposited on
titanium-lined features on a dielectric layer.
[0049] Three substrates were separately polished with three
different polishing compositions. Compositions 4A-4C. Each of the
polishing compositions contained about 0.5 wt. % of .alpha.-alumina
treated with about 1150 ppm of
polyacrylic-co-polyacrylamido-2-methylpropane sulfonic acid, about
1 wt. % of lactic acid, and about 3 wt. % of hydrogen peroxide in
water at a pH of 3.4. Composition 4A (control) further contained
1000 ppm of a polycarboxylic acid polymer having a molecular weight
of 100,000. Composition 4B (comparative) further contained 1000 ppm
of Calsoft LAS99 (a C.sub.12-C.sub.16 linear
alkylbenzenesulfonate). Composition 4C (invention) further
contained 1000 ppm of Dowfax.TM. 8390 (an alkyldiphenyloxide
sulfonate surfactant).
[0050] Following polishing, the substrates were cleaned. The amount
of aluminum dishing was measured, and the defectivity was inspected
by an AIT wafer inspection system. Total scratch defects were
determined as the number of images with scratches as observed by
the AIT system. The results are set forth in Table 4.
TABLE-US-00004 TABLE 4 A1 Removal Rate Dishing Total Scratch
Composition Additive (.ANG./min) (.ANG.) Defects 4A (control)
Polycarboxylic 1900 44 2500 acid 4B (comparative) Calsoft LAS99
1900 67 2500 4C (invention) Dowfax .TM. 2300 66 32 8390
[0051] As is apparent from the results set forth in Table 4,
inventive Composition 4C, which contained an alkyldiphenyloxide
disulfonate surfactant (Dowfax.TM. 8390) as the additive, exhibited
approximately 1.3% of total scratch defects as compared with
control Composition 4A, which contained a polycarboxylic acid as
the additive, and Composition 4B, which contained a
C.sub.12-C.sub.16 linear alkylbenzenesulfonate (Calsoft LAS99) as
the additive.
[0052] All references, including publications, patent applications,
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0053] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. Recitation of ranges of values herein are
merely intended to serve as a shorthand method of referring
individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0054] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. Variations of those preferred embodiments may
become apparent to those of ordinary skill in the art upon reading
the foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *