U.S. patent application number 14/770185 was filed with the patent office on 2016-01-14 for chemical-mechanical polishing compositions comprising n,n,n',n'-tetrakis-(2-hydroxypropyl)-ethylenediamine or methanesulfonic acid.
This patent application is currently assigned to BASF SE. The applicant listed for this patent is BASF SE. Invention is credited to Zhenyu BAO, Yongqing LAN, Julian PROELSS, Peter PRZYBYLSKI.
Application Number | 20160009955 14/770185 |
Document ID | / |
Family ID | 48366260 |
Filed Date | 2016-01-14 |
United States Patent
Application |
20160009955 |
Kind Code |
A1 |
LAN; Yongqing ; et
al. |
January 14, 2016 |
CHEMICAL-MECHANICAL POLISHING COMPOSITIONS COMPRISING
N,N,N',N'-TETRAKIS-(2-HYDROXYPROPYL)-ETHYLENEDIAMINE OR
METHANESULFONIC ACID
Abstract
Described is a chemical-mechanical polishing (CMP) composition
comprising the following components: (A) surface modified silica
particles having a negative zeta potential of -15 mV or below at a
pH in the range of from 2 to 6 (B)
N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid (C) water (D) optionally one or more further
constituents, wherein the pH of the composition is in the range of
from 2 to 6.
Inventors: |
LAN; Yongqing;
(Ludwigshafen, DE) ; PRZYBYLSKI; Peter;
(Ludwigshafen, DE) ; BAO; Zhenyu; (Potsdam,
NY) ; PROELSS; Julian; (Worms, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BASF SE |
Ludwigshafen |
|
DE |
|
|
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
48366260 |
Appl. No.: |
14/770185 |
Filed: |
May 6, 2014 |
PCT Filed: |
May 6, 2014 |
PCT NO: |
PCT/IB2014/061236 |
371 Date: |
August 25, 2015 |
Current U.S.
Class: |
438/692 ;
252/79.4 |
Current CPC
Class: |
C09K 3/1436 20130101;
C09K 3/1463 20130101; C09G 1/02 20130101; H01L 21/30625
20130101 |
International
Class: |
C09G 1/02 20060101
C09G001/02; H01L 21/306 20060101 H01L021/306 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 2013 |
EP |
13167899.7 |
Claims
1. A chemical-mechanical polishing (CMP) composition comprising:
(A) surface modified silica particles having a negative zeta
potential of -15 mV or below at a pH in the range of from 2 to 6,
(B) N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid, (C) water (D) optionally one or more further
constituents, wherein the pH of the composition is in the range of
ranges from 2 to 6.
2. The chemical-mechanical polishing (CMP) composition according to
claim 1, wherein the surface modified silica particles of component
(A) having a negative zeta potential of -15 mV or below at a pH in
the range of from 2 to 6 are silica particles anionically modified
with metallate ions or modified with sulfonic acid.
3. The chemical-mechanical polishing (CMP) composition according to
claim 1, wherein the surface modified silica particles of component
(A) having a negative zeta potential of -15 mV or below at a pH in
the range of from 2 to 6 are silica particles anionically modified
with metallate ions selected from the group consisting of
aluminate, stannate, zincate, and plumbate.
4. The chemical-mechanical polishing (CMP) composition according to
claim 1, wherein the surface modified silica particles of component
(A) having a negative zeta potential of -15 mV or below at a pH in
the range of from 2 to 6 are silica particles anionically modified
with aluminate.
5. The chemical-mechanical polishing (CMP) composition according to
claim 1, wherein the total amount of (A) surface modified silica
particles having a negative zeta potential of -15 mV or below at a
pH in the range of from 2 to 6 is in the range of from 0,1 wt % to
30 wt %, based on the total weight of the chemical-mechanical
polishing (CMP) composition and/or the total amount of (B)
N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid is in the range of from 0.01 to 3 wt % based
on the total weight of the chemical-mechanical polishing (CMP)
composition.
6. A chemical-mechanical polishing (CMP) composition according to
claim 1, comprising one or more further constituents as component
(D), wherein the one or at least one of or all of the further
constituents of component (D) are selected from the group
consisting of oxidizing agents, abrasive materials different from
surface modified silica particles having a negative zeta potential
of -15 mV or below at a pH in the range of from 2 to 6,
stabilizers, surfactants, friction reducing agents, and buffer
substances.
7. A method for chemical-mechanical polishing comprising contacting
a material with a chemical-mechanical polishing (CMP) composition
that comprises N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine
or methanesulfonic acid.
8. The method according to claim 7, wherein the CMP composition
comprises an additive for increasing the removal rate of a III-V
material.
9. The method according to claim 8, wherein the III-V material is
selected from the group consisting of GaN, GaP, GaAs, GaSb, AlAs,
AlN, InP, InAs, InSb, InGaAs, InAlAs, AlGaAs, GaAlN, GaInN,
InGaAlAs, InGaAsP, InGaP, AlInP, GaAlSb, GaInSb, GaAlAsSb, and
GaInAsSb.
10. A process for the manufacture of semiconductor devices
comprising chemical-mechanical polishing of a substrate or layer in
the presence of a chemical-mechanical polishing (CMP) composition
as defined in claim 1.
11. The process according to claim 10, wherein the substrate or
layer contains one or more III-V materials.
12. The process according to claim 10, wherein at least one of the
III-V materials is selected from the group consisting of GaN, GaP,
GaAs, GaSb, AlAs, AlN, InP, InAs, InSb, InGaAs, InAlAs, AlGaAs,
GaAlN, GaInN, InGaAlAs, InGaAsP, InGaP, AlInP, GaAlSb, GaInSb,
GaAlAsSb, and GaInAsSb.
13. A method for polishing a substrate or layer containing one or
more III-V materials comprising contacting it with the CMP
composition of claim 1.
14. The method according to claim 13, wherein at least one of the
III-V materials is selected from the group consisting of GaN, GaP,
GaAs, GaSb, AlAs, AlN, InP, InAs, InSb, InGaAs, InAlAs, AlGaAs,
GaAlN, GaInN, InGaAlAs, InGaAsP, InGaP, AlInP, GaAlSb, GaInSb,
GaAlAsSb, and GaInAsSb.
15. The method according to claim 7, wherein said CMP composition
comprises surface modified silica particles having a negative zeta
potential of -15 mV or below at a pH in the range of from 2 to 6.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a chemical-mechanical
polishing composition comprising surface modified silica particles
having a negative zeta potential of -15 mV or below at a pH in the
range of from 2 to 6 and
N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid, as well as to the use of
N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid as additive for a chemical mechanical
polishing (CMP) composition. The present invention also relates to
a process for the manufacture of semiconductor devices comprising
the chemical-mechanical polishing of a substrate or layer in the
presence of said chemical-mechanical polishing (CMP)
composition.
DESCRIPTION OF THE PRIOR ART
[0002] In the semiconductor industry, chemical mechanical polishing
is a well-known technology applied in fabricating advanced
photonic, microelectromechanical and microelectronic materials and
devices, such as semiconductor wafers.
[0003] During the fabrication of materials and devices used in the
semiconductor industry, CMP is employed to planarize surfaces. CMP
utilizes the interplay of chemical and mechanical action to achieve
the planarity of the to-be-polished surfaces. Chemical action is
provided by a chemical composition, also referred to as CMP
composition or CMP slurry. Mechanical action is usually carried out
by a polishing pad which is typically pressed onto the
to-be-polished surface and mounted on a moving platen. The movement
of the platen is usually linear, rotational or orbital.
[0004] In a typical CMP process step, a rotating wafer holder
brings the to-be-polished wafer in contact with a polishing pad.
The CMP composition is usually applied between the to-be-polished
wafer and the polishing pad.
[0005] In the state of the art, CMP processes in the presence of a
CMP composition comprising surface modified silica particles are
known and described, for instance, in the following references.
[0006] WO 2006/028759 A2 describes an aqueous slurry composition
for polishing/planarization substrates which are utilized in the
process of metal interconnect formation on IC devices. Said slurry
comprising silicon dioxide abrasive particles wherein said abrasive
particles are anionically modified/doped with metallate anions
selected from the group consisting of aluminate, stannate, zincate
and plumbate, thereby providing a high negative surface charge to
said abrasive particles and enhancing the stability of said slurry
composition.
[0007] EP 2 533 274 A1 discloses a chemical mechanical polishing
aqueous dispersion comprising (A) silica particles that include at
least one functional group selected from a group consisting of a
sulfo group and salts thereof, and (B) an acidic compound.
OBJECTS OF THE INVENTION
[0008] One of the objects of the present invention is to provide a
CMP composition and a CMP process especially for the
chemical-mechanical polishing of III-V materials, particularly GaAs
and InP substrates which are utilized in the front-end-of-line
(FEOL) IC production to form transistors, and showing an improved
polishing performance, especially
[0009] (i) a high material removal rate (MRR) of a III-V material,
for example GaAs and/or InP,
[0010] (ii) high surface quality of the III-V material, for example
GaAs and/or InP, after the CMP step,
[0011] (iii) safe handling and reduction of hazardous
by-products--for example the toxic gasses AsH.sub.3 and/or PH.sub.3
in case of polishing GaAs and/or InP--to a minimum, or
[0012] (iv) or the combination of (i), (ii) and (iii).
[0013] Moreover, a CMP process was sought that is easy to apply and
requires as few steps as possible.
SUMMARY OF THE INVENTION
[0014] According to a first aspect of the present invention, a
chemical-mechanical polishing (CMP) composition is provided
comprising the following components:
[0015] (A) surface modified silica particles having a negative zeta
potential of -15 mV or below at a pH in the range of from 2 to
6,
[0016] (B) N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid,
[0017] (C) water,
[0018] (D) optionally one or more further constituents,
[0019] wherein the pH of the composition is in the range of from 2
to 6.
[0020] In a further aspect, the present invention relates to the
use of N,N,N',N'-tetrakis-(2hydroxypropyl)-ethylenediamine or
methanesulfonic acid as an additive for a chemical-mechanical
polishing (CMP) composition, preferably as an additive for a
chemical-mechanical polishing (CMP) composition comprising surface
modified silica particles having a negative zeta potential of -15
mV or below at a pH in the range of from 2 to 6. A preferred use
according to the invention is the use of
N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid as an additive for a chemical-mechanical
polishing (CMP) composition, wherein the additive is an additive
for increasing the removal rate of a III-V material, wherein the
III-V material is preferably selected from the group consisting of
GaN, GaP, GaAs, GaSb, AlAs, AlN, InP, InAs, InSb, InGaAs, InAlAs,
AlGaAs, GaAlN, GaInN, InGaAlAs, InGaAsP, InGaP, AlInP, GaAlSb,
GaInSb, GaAlAsSb and GaInAsSb.
[0021] According to a further aspect of the invention there is
provided a process for the manufacture of semiconductor devices
comprising the chemical-mechanical polishing of a substrate or
layer in the presence of a chemical-mechanical polishing (CMP)
composition as defined hereinabove or hereinbelow.
[0022] Generally, the semiconductor device which can be
manufactured by the process according to the invention is not
particularly limited. Thus the semiconductor devices can be
electronic components comprising semiconducting materials, as for
example silicon, germanium, and III-V materials. Semiconductor
devices can be those which are manufactured as single discrete
devices or those which are manufactured as integrated circuits
(ICs) consisting of a number of devices manufactured and
interconnected on a wafer. Semiconductor devices can be two
terminal devices for example a diode, three terminal devices for
example a bipolar transistor, four terminal devices for example a
Hall effect sensor or multi-terminal devices. Preferably, said
semiconductor device is a multi-terminal device. Multi-terminal
devices can be logic devices as integrated circuits and
microprocessors or memory devices as random access memory (RAM),
read only memory (ROM) and phase change random access memory
(PCRAM). Preferably said semiconductor device is a multi-terminal
logic device. In particular said semiconductor device is an
integrated circuit or microprocessor.
[0023] In a further aspect, the present invention relates to the
use of a chemical-mechanical polishing (CMP) composition as defined
hereinabove or hereinbelow for polishing a substrate or layer
containing one or more III-V materials wherein the or at least one
of or all III-V materials are preferably selected from the group
consisting of GaN, GaP, GaAs, GaSb, AlAs, AlN, InP, InAs, InSb,
InGaAs, InAlAs, AlGaAs, GaAlN, GaInN, InGaAlAs, InGaAsP, InGaP,
AlInP, GaAlSb, GaInSb, GaAlAsSb, and GaInAsSb.
[0024] Preferred embodiments are explained in the claims and the
specification. It is understood that combinations of preferred
embodiments are within the scope of the present invention.
[0025] In a preferred process according to the present invention
the substrate or layer contains one or more III-V materials.
Preferably the one or at least one of or all the III-V materials
are selected from the group consisting of GaN, GaP, GaAs, GaSb,
AlAs, AlN, InP, InAs, InSb, InGaAs, InAlAs, AlGaAs, GaAlN, GaInN,
InGaAlAs, InGaAsP, InGaP, AlInP, GaAlSb, GaInSb, GaAlAsSb and
GaInAsSb.
[0026] A semiconductor device can be manufactured by the process of
the invention. Said process preferably comprises the chemical
mechanical polishing of a substrate or layer--preferably a
layer--containing one or more III-V materials in the presence of
the CMP composition as defined hereinabove or hereinbelow.
[0027] If the III-V material has the shape of a layer, the content
of all III-V material contained in the layer is preferably more
than 90%, more preferably more than 95%, most preferably more than
98%, particularly more than 99%, for example more than 99.9% by
weight of the corresponding layer. A III-V material is a material
consisting of at least one group 13 element (including Al, Ga, In)
and at least one group 15 element (including N, P, As, Sb). The
terms "group 13" and "group 15" refer to the current IUPAC
convention for naming the groups in the periodic table of chemical
elements. Preferably, said III-V material is GaN, GaP, GaAs, GaSb,
AlAs, AlN, InP, InAs, InSb, InGaAs, InAlAs, AlGaAs, GaAlN, GaInN,
InGaAlAs, InGaAsP, InGaP, AlInP, GaAlSb, GaInSb, GaAlAsSb, or
GaInAsSb. More preferably, said III-V material is GaN, GaP, GaAs,
GaSb, InP, InAs, InSb, InGaAs, or InAlAs. Most preferably, said
III-V material is GaN, GaP, GaAs, GaAs, InP, or InAs. Particularly,
said III-V material is GaAs (gallium arsenide) and/or InP (indium
phosphide).
[0028] The CMP composition of the present invention is used for
chemical-mechanical polishing of a substrate or layer--preferably a
layer--containing one or more III-V materials, preferably for
chemical-mechanical polishing of a layer containing one or more
III-V materials. If the III-V material has the shape of a layer,
the content of all III-V material contained in the layer is
preferably more than 90%, more preferably more than 95%, most
preferably more than 98%, particularly more than 99%, for example
more than 99.9% by weight of the corresponding layer. Preferably,
said III-V material is GaN, GaP, GaAs, GaSb, AlAs, AlN, InP, InAs,
InSb, InGaAs, InAlAs, AlGaAs, GaAlN, GaInN, InGaAlAs, InGaAsP,
InGaP, AlInP, GaAlSb, GaInSb, GaAlAsSb, or GaInAsSb. More
preferably, said III-V material is GaN, GaP, GaAs, GaSb, InP, InAs,
InSb, InGaAs, or InAlAs. Most preferably, said III-V material is
GaN, GaP, GaAs, GaAs, InP, or InAs. Particularly, said III-V
material is GaAs (gallium arsenide) and/or InP (indium
phosphide).
[0029] The CMP composition of the present invention comprises the
components (A), (B), and (C) water and optionally further component
(D) as described below.
[0030] Component (A): surface modified silica particles having a
negative zeta potential of -15 mV or below at a pH in the range of
from 2 to 6
[0031] The surface-modified silica particles have a zeta potential
more negative than -15 mV, preferably, more negative than -25 mV,
and most preferably more negative than -30 mV.
[0032] The surface modified silica particles are silica particles,
preferably colloidal silica particles which are stabilized as the
result of changes of the surface of the particles. The
surface-modified silica particles are preferably amorphous and not
agglomerated and thus typically occur in the form of discrete
spheres that are not crosslinked with each other and contain
hydroxyl groups on the surface. Colloidal silica particles are
obtainable by methods known in the art such as ion-exchange of
silicic acid salt, or by sol-gel technique (e.g., hydrolysis or
condensation of a metal alkoxide, or peptization of precipitated
hydrated silicon oxide, etc.).
[0033] Preferably the surface modified silica particles of
component (A) having a negative zeta potential of -15 mV or below
at a pH in the range of from 2 to 6 are silica particles
anionically modified with metallate ions or modified with sulfonic
acid.
[0034] Sulfonic acid-modified aqueous anionic silica sols which are
highly stable under acidic conditions are disclosed e.g. in WO
2010734542 A1. Herein, a sulfonic acid-modified aqueous anionic
silica sol is obtained by a method wherein a silane coupling agent
having a functional group which can be chemically converted into a
sulfonic acid group is added to colloidal silica, and then the
functional group is converted into a sulfonic acid group.
[0035] The term "anionically modified with metallate ions" as
utilized herein in particular refers to silica particles where
metallate ions (i.e., M(OH).sub.4.sup.--) are incorporated in the
surface of the silica particle replacing Si(OH).sub.4 sites and
creating a permanent negative charge, as explained in WO
2006/028759 A2.
[0036] Preferably the surface modified silica particles of
component (A) having a negative zeta potential of -15 mV or below
at a pH in the range of from 2 to 6 are silica particles
anionically modified with metallate ions selected from the group
consisting of aluminate, stannate, zincate, and plumbate. Most
preferably the surface modified silica particles of component (A)
having a negative zeta potential of -15 mV or below at a pH in the
range of from 2 to 6 are silica particles anionically modified with
aluminate. Such surface modified silica particles are disclosed
e.g. in WO 2006/7028759 A2.
[0037] Generally, the particles (A) can be contained in varying
amounts in the CMP composition of the present invention.
Preferably, the amount of (A) is not more than 30 wt. % (wt. % in
each case stands for "percent by weight"), more preferably not more
than 5 wt. %, most preferably not more than 3 wt. %, particularly
preferably not more than 2.5 wt. %, for example not more than 1.5
wt. %, in each case based on the total weight of the composition of
the present invention. Preferably, the amount of (A) is at least
0.1 wt. %, particularly at least 0.4 wt. %, for example 1 wt. %, in
each case based on the total weight of the composition of the
present invention.
[0038] Generally, the particles (A) can be contained in varying
particle size distributions. The particle size distributions of the
particles (A) can be monomodal or multimodal. In case of multimodal
particle size distributions, bimodal is often preferred. In order
to have an easily reproducible property profile and easily
reproducible conditions during the CMP process of the invention, a
monomodal particle size distribution is preferred for (A). It is
most preferred for (A) to have a monomodal particle size
distribution.
[0039] The average particle size of the surface-modified silica is
preferably in the range of from 1 to 200 nm, preferably of from 5
to 140 nm, and most preferably of from 10 to 100 nm. The term
"particle size" as utilized herein refers to the average diameter
of particles as measured by standard particle sizing instruments
and methods, such as dynamic light scattering techniques, laser
diffusion diffraction techniques, ultracentrifuge analysis
techniques, etc. If not indicated otherwise dynamic light
scattering techniques are preferred.
[0040] The BET surface determined according to DIN ISO 9277 of the
silica particles can vary within a wide range. Preferably, the BET
surface of the silica particles is in the range of from 1 to 500
m.sup.2/g, more preferably in the range of from 5 to 350 m.sup.2/g,
most preferably in the range of from 10 to 300 m.sup.2/g, in
particular in the range of from 50 to 250 m.sup.2/g, for example in
the range of from 100 to 220 m.sup.2/g.
[0041] Component (B):
N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid
[0042] Generally, the component (B)
(N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid) can be contained in varying amounts in the
CMP composition of the present invention. Preferably, the amount of
(B) is not more than 3 wt. % (wt. % in each case stands for
"percent by weight"), more preferably not more than 2 wt. %, most
preferably not more than 1 wt. %, particularly preferably not more
than 0.5 wt. %, based in each case on the total weight of the
composition of the present invention. Preferably, the amount of (B)
is at least 0.01 wt. %, particularly at least 0.05 wt. %, for
example 0.1 wt. %, based in each case on the total weight of the
composition of the present invention.
[0043] If the CMP composition of the present invention comprises
N,N,N',N'-tetrakis-(2-hydroxypropyl)ethylenediamine (in component
(B)), the simultaneous presence of methanesulfonic acid is not
preferred, and vice versa. Thus, preferably the composition
comprises either
N,N,N',N'-tetrakis(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid in component (B), while the respective other
compound of component (B) is not present in the composition.
[0044] N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine as well
as methanesulfonic acid are commercially available, for example as
Lutropor.RTM. Q75 (BASF SE) and Lutropor.RTM. MSA (BASF SE), resp,
and the way of preparing said compounds is known to those skilled
in the art.
Optional Further Constituents (D)
[0045] A CMP composition according to the present invention may
comprise further constituents, depending on the specific
requirements of the intended use of said CMP composition.
Preferably the one or at least one of or all of the further
constituents of component (D) are selected from the group
consisting of oxidizing agents, abrasive materials different from
surface modified silica particles having a negative zeta potential
of -15 mV or below at a pH in the range of from 2 to 6,
stabilizers, surfactants, friction reducing agents, buffer
substances.
[0046] The CMP composition of the present invention can further
optionally comprise one or more types of oxidizing agent (D1),
preferably one to two types of oxidizing agent (D1), more
preferably one type of oxidizing agent (D1). The oxidizing agent
(D1) is different from the components (A), (B) and (C) water. In
general, the oxidizing agent is a compound which is capable of
oxidizing the to-be-polished substrate or one of its layers.
Preferably, (D1) is a per-type oxidizer. More preferably, (D1) is a
peroxide, persulfate, perchlorate, perbromate, periodate,
permanganate, or a derivative thereof. Most preferably, (D1) is a
peroxide or persulfate. Particularly, (D1) is a peroxide. For
example, (D1) is hydrogen peroxide.
[0047] If present, the oxidizing agent (D1) can be contained in
varying amounts in the CMP composition of the present invention.
Preferably, the amount of (D1) is not more than 20 wt. % (wt. % in
each case stands for "percent by weight"), more preferably not more
than 10 wt. %, most preferably not more than 5 wt. %, particularly
not more than 3.5 wt. %, for example not more than 2.7 wt. %, in
each case based on the total weight of the CMP composition of the
present invention. Preferably, the amount of (D1) is at least 0.01
wt. %, more preferably at least 0.08 wt. %, most preferably at
least 0.4 wt. %, particularly at least 0.75 wt. %, for example at
least 1 wt. %, in each case based on the total weight of the
composition of the present invention. If hydrogen peroxide is used
as oxidizing agent (D1), the amount of (D1) is preferably 1 wt. %
to 5 wt. %, more preferably 2 wt. % to 3.5 wt. %, for instance 2.5
wt. %, in each case based on the total weight of the CMP
composition of the present invention.
[0048] The CMP composition of the present invention can further
optionally contain one or more biocides (D2), for example one
biocide. The biocide (D2) is different from the components (A),
(B), (C) and from constituent (D1) of component (D). In general,
the biocide is a compound which deters, renders harmless, or exerts
a controlling effect on any harmful organism by chemical or
biological means. Preferably, (D2) is an quaternary ammonium
compound, an isothiazolinone-based compound, an N-substituted
diazenium dioxide, or an N-hydroxy-diazenium oxide salt. More
preferably, (D2) is an N-substituted diazenium dioxide, or an
N-hydroxy-diazenium oxide salt.
[0049] If present, the biocide (D2) can be contained in varying
amounts in the CMP composition of the present invention. If
present, the amount of (D2) is preferably not more than 0.5 wt. %
(wt. % in each case stands for "percent by weight"), more
preferably not more than 0.1 wt. %, most preferably not more than
0.05 wt. %, particularly not more than 0.02 wt. %, for example not
more than 0.008 wt. %, in each case based on the total weight of
the corresponding composition. If present, the amount of (D2) is
preferably at least 0.0001 wt. %, more preferably at least 0.0005
wt. %, most preferably at least 0.001 wt. %, particularly at least
0.003 wt. %, for example at least 0.006 wt. %, in each case based
on the total weight of the corresponding CMP composition of the
present invention.
[0050] The CMP composition of the present invention can further
optionally contain one or more corrosion inhibitors (D3), for
example one corrosion inhibitor. The corrosion inhibitor (D3) is
different from the components (A), (B), (C) and from constituents
(D1) and (D2) of component (D). In general, all compounds forming a
protective molecular layer on the surface of a III-V material--for
example GaAs--can be used as corrosion inhibitor. Suitable
corrosion inhibitors are known in the art.
[0051] If present, the corrosion inhibitor (D3) can be contained in
varying amounts in the CMP composition of the present invention. If
present, the amount of (D3) is preferably not more than 10 wt. %
(wt. % in each case stands for "percent by weight"), more
preferably not more than 2 wt. %, most preferably not more than 0.5
wt. %, particularly not more than 0.1 wt. %, for example not more
than 0.05 wt. %, in each case based on the total weight of the
corresponding composition. If present, the amount of (D3) is
preferably at least 0.0005 wt. %, more preferably at least 0.005
wt. %, most preferably at least 0.025 wt. %, particularly at least
0.1 wt. %, for example at least 0.4 wt. %, in each case based on
the total weight of the composition of the present invention.
[0052] The properties of the CMP composition of the present
invention, such as stability and polishing performance, may depend
on the pH of the corresponding composition. The pH value of the CMP
composition of the present invention is in the range of from 2 to 6
preferably from 2.2 to 6, more preferably from 2.5 to 5.8, further
preferably from 2.5 to 5.5, still further preferably from 2.8 to
5.5, especially preferably from 3 to 5.2, particularly preferably
from 3 to 5, more particular preferably from 3.2 to 5, particularly
from 3.5 to 4.5, for example 4.
[0053] The CMP composition of the present invention can further
optionally contain one or more buffer substances (D4). The buffer
substance (D4) is different from the components (A), (B), (C) and
from constituents (D1), (D2) and (D3) of component (D). In general,
the buffer substance (D4) is a compound which is added to the CMP
composition of the present invention to have its pH value adjusted
to the required value. Preferred buffer substances are inorganic
acids, carboxylic acids, amine bases, alkali hydroxides, ammonium
hydroxides, including tetraalkylammonium hydroxides. For example,
the buffer substance (D4) is nitric acid, sulfuric acid, ammonia,
sodium hydroxide, or potassium hydroxide.
[0054] If present, the buffer substance (D4) can be contained in
varying amounts in the CMP composition of the present invention. If
present, the amount of (D4) is preferably not more than 10 wt. %
(wt. % in each case stands for "percent by weight"), more
preferably not more than 2 wt. %, most preferably not more than 0.5
wt. %, particularly not more than 0.1 wt. %, for example not more
than 0.05 wt. %, in each case based on the total weight of the
corresponding composition. If present, the amount of (D4) is
preferably at least 0.0005 wt. %, more preferably at least 0.005
wt. %, most preferably at least 0.025 wt. %, particularly at least
0.1 wt. %, for example at least 0.4 wt. %, in each case based on
the total weight of the CMP composition of the present
invention.
[0055] The CMP composition of the present invention may also
contain, if necessary, one or more other additives, including but
not limited to stabilizers, surfactants, friction reducing agents,
etc. Said other additives is different from the components (A) (B),
(C), and from constituents (D1), (D2), (D3) and (D4) of component
(D). Said other additives are for instance those commonly employed
in CMP compositions and thus known to the person skilled in the
art. Such addition can for example stabilize the dispersion, or
improve the polishing performance, or the selectivity between
different layers.
[0056] If present, said other additive can be contained in varying
amounts in the CMP composition of the present invention.
Preferably, the total amount of said other additives is not more
than 10 wt. % (wt. % in each case stands for "percent by weight"),
more preferably not more than 2 wt. %, most preferably not more
than 0.5 wt. %, particularly not more than 0.1 wt. %, for example
not more than 0.01 wt. %, in each case based on the total weight of
the corresponding CMP composition. Preferably, the total amount of
said other additives is at least 0.0001 wt. %, more preferably at
least 0.001 wt. %, most preferably at least 0.008 wt. %,
particularly at least 0.05 wt. %, for example at least 0.3 wt. %,
in each case based on the total weight of the corresponding CMP
composition of the present invention.
[0057] Preferably, the chemical-mechanical polishing (CMP)
composition does not comprise any abrasive materials different from
above-defined surface modified silica particles having a negative
zeta potential of -15 mV or below at a pH in the range of from 2 to
6.
[0058] Particularly preferred is a chemical-mechanical polishing
(CMP) composition according to the present invention wherein [0059]
the total amount of (A) surface modified silica particles having a
negative zeta potential of -15 mV or below at a pH in the range of
from 2 to 6 is in the range of from 0.1 to 30 wt. % based on the
total weight of the CMP composition of the present invention and/or
[0060] the total amount of (B)
N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine or
methanesulfonic acid is in the range of from 0.01 to 3 wt %, based
on the total weight of the CMP composition of the present
invention.
[0061] It is understood that the above-defined preferred CMP
compositions of the present invention have a pH of from 2 to 6 as
described above.
[0062] Processes for preparing CMP compositions are generally
known. These processes may be applied to the preparation of the CMP
composition of the present invention. This can be carried out by
dispersing or dissolving the above-described components (A) and
(B), and if appropriate the optional further constituents of
component (D) in water, and optionally by adjusting the pH value
through adding a buffer substance (D4) as defined hereinabove or
hereinbelow. For this purpose the customary and standard mixing
processes and mixing apparatuses such as agitated vessels, high
shear impellers, ultrasonic mixers, homogenizer nozzles or
counterflow mixers, can be used.
[0063] The CMP composition of the present invention is preferably
prepared by dispersing the particles (A), dispersing and/or
dissolving (B) N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine
or methanesulfonic acid and optionally dispersing and/or dissolving
the further constituents (D) in water (C).
[0064] The polishing process is generally known and can be carried
out with the processes and the equipment under the conditions
customarily used for the CMP in the fabrication of wafers with
integrated circuits. There is no restriction on the equipment with
which the polishing process can be carried out.
[0065] As is known in the art, typical equipment for the CMP
process consists of a rotating platen which is covered with a
polishing pad. Also orbital polishers have been used. The wafer is
mounted on a carrier or chuck. The side of the wafer being
processed is facing the polishing pad (single side polishing
process). A retaining ring secures the wafer in the horizontal
position.
[0066] Below the carrier, the larger diameter platen is also
generally horizontally positioned and presents a surface parallel
to that of the wafer to be polished. The polishing pad on the
platen contacts the wafer surface during the planarization
process.
[0067] To produce material loss, the wafer is pressed onto the
polishing pad. Both the carrier and the platen are usually caused
to rotate around their respective shafts extending perpendicular
from the carrier and the platen. The rotating carrier shaft may
remain fixed in position relative to the rotating platen or may
oscillate horizontally relative to the platen. The direction of
rotation of the carrier is typically, though not necessarily, the
same as that of the platen. The speeds of rotation for the carrier
and the platen are generally, though not necessarily, set at
different values. During the CMP process of the invention, the CMP
composition of the present invention is usually applied onto the
polishing pad as a continuous stream or in dropwise fashion.
Customarily, the temperature of the platen is set at temperatures
of from 10 to 70.degree. C.
[0068] The load on the wafer can be applied by a flat plate made of
steel for example, covered with a soft pad that is often called
backing film. If more advanced equipment is being used a flexible
membrane that is loaded with air or nitrogen pressure presses the
wafer onto the pad. Such a membrane carrier is preferred for low
down force processes when a hard polishing pad is used, because the
down pressure distribution on the wafer is more uniform compared to
that of a carrier with a hard platen design. Carriers with the
option to control the pressure distribution on the wafer may also
be used according to the invention. They are usually designed with
a number of different chambers that can be loaded to a certain
degree independently from each other.
[0069] For further details reference is made to WO 2004/063301 A1,
in particular page 16, paragraph [0036] to page 18, paragraph
[0040] in conjunction with the FIG. 2.
[0070] By way of the CMP process of the invention, wafers with
integrated circuits comprising a dielectric layer can be obtained
which have an excellent functionality, especially when the
substrate or layer to be polished contains one or more III-V
materials.
[0071] The CMP composition of the present invention can be used in
the CMP process as ready-to-use slurry, they have a long shelf-life
and show a stable particle size distribution over long time. Thus,
they are easy to handle and to store. They show an excellent
polishing performance, particularly with regard to high material
removal rate (MRR) and high surface quality combined with minimal
generation of the toxic gasses AsH.sub.3 and PH.sub.3. Since the
amounts of its components are held down to a minimum, the CMP
composition of the present invention and the CMP process according
to the invention can be used or applied in a cost-effective
way.
EXAMPLES AND COMPARATIVE EXAMPLES
General procedure for the CMP Experiments
[0072] For the evaluation on benchtop polisher, the following
parameters were chosen:
[0073] Procedure setting: Phoenix 4000 polisher; table/carrier
200/150 rpm; down force 2.5 psi (17238 Pa); slurry flow rate 18
mL/min; pad IC 1000; time 1 min.
[0074] The pad is conditioned by several sweeps, before a new type
of CMP composition is used for CMP. For the determination of
removal rates at least 3 wafers are polished and the data obtained
from these experiments are averaged.
[0075] The CMP composition is stirred in the local supply
station.
[0076] Object to be polished: unstructured GaAs wafers and
unstructured InP wafers.
[0077] The GaAs material removal rates (referred to as "GaAs-MRR"
in the following) for 2 inch (=5.08 cm) discs polished by the CMP
composition are determined by difference of weight of the coated
wafers or blanket discs before and after CMP, using a Sartorius
LA310 S scale. The difference of weight can be converted into the
difference of film thickness since the density (5.32 g/cm.sup.3 for
GaAs) and the surface area of the polished material are known.
Dividing the difference of film thickness by the polishing time
provides the values of the material removal rate. The InP material
removal rates (referred to as "InP-MRR" in the following) were
determined in the same manner.
[0078] The surface quality of GaAs layers and InP layers was
measured by root mean square roughness (RMS) on polished substrates
with Atomic Force Microscopy (AFM) (Dimension FastScan, Bruker)
with scan area 5 .mu.m.times.5 .mu.m using Tapping Mode.TM.
(=intermittent contact mode) as scanning mode.
Standard Procedure for Slurry Preparation:
[0079] The components (A), (B) and (D1)--each in the amounts as
indicated in table 1--were dispersed or dissolved in de-ionized
water. pH is adjusted by adding of aqueous 10% KOH solution or
HNO.sub.3 (0.1%-10%) solution to the slurry. The pH value is
measured with a pH electrode (Schott, blue line, pH 0-14/-5 . . .
100.degree. C. / 3 mol/L sodium chloride).
Measurement of the Zeta Potential
[0080] For measuring electrophoretic mobility and zeta potential of
the silica particles (A) a standard Zetasizer Nano device from the
company Malvern was used. The samples were diluted by a factor of
500 with 10 mmol/l KCl solution before measuring the mobility. The
measurements were done at 23.degree. C.
Examples 1 and 2 and Comparative Examples 1 and 2
[0081] In comparative example 1 and examples 1 and 2 according to
the invention, the particles (A) are aluminate-modified anionic
colloidal silica having a typical particle size of 15 nm, a typical
surface area of 200 m.sup.2/g and a zeta potential of -40 mV at pH
4, e.g. Levasil.RTM. 200A (from Akzo Nobel).
[0082] In comparative example 1, no additive (B) is present.
[0083] In comparative example 2, benzotriazole is present as
additive (B).
[0084] In example 1 according to the invention, the additive (B) is
N,N,N',N'-tetrakis-(2-hydroxypropyl)ethylenediamine e.g.
Lutropor.RTM. Q75 (BASF SE).
[0085] In example 2 according to the invention the additive (B) is
methanesulfonic acid, e.g. Lutropor.RTM. MSA (BASF SE).
[0086] Aqueous dispersions containing the components (A), (B) and
(D1) as listed in table 1 were prepared, and the polishing
performance data compiled in table 1 were determined.
TABLE-US-00001 Comparative Comparative example 1 example 2 Example
1 Example 2 Particles (A) 3.0 wt. % 3.0 wt. % 3.0 wt. % 3.0 wt. %
(aluminate- modified silica) Additive (B) None Benzotrizole,
N,N,N',N'- methane- 0.1 wt. % tetrakis-(2- sulfonic hydroxypropyl)-
acid, ethylenediamine 0.1 wt. % 0.1 wt. % Oxidizing H.sub.2O.sub.2
H.sub.2O.sub.2 H.sub.2O.sub.2 1.5 wt. % H.sub.2O.sub.2 agent (D1)
1.5 wt. % 1.5 wt. % 1.5 wt. % pH 4 4 4 4 GaAs MRR* 2149 914 2358
2605 (.ANG./min) InP MRR 2551 312 2984 3671 (.ANG./min) RMS on
>3 >3 >3 >3 GaAs (nm) RMS on InP <0.5 <0.5
<0.5 <0.5 (nm)
[0087] The data in table 1 show that the additive (B) according to
the present invention causes in increase of the material removal
rate (MRR) on both GaAs and InP substrates. However. this effect is
unique to the combination of the surface-modified silica particles
(A) having a negative zeta potential of -15 mV or below at a pH in
the range of from 2 to 6 with an additive (B) according to the
invention, since replacement of the additive (B) according to the
invention by another common additives like benzotriazole results in
a decrease of both material removal rates. Despite the increase of
the material removal rates, the surface quality was not compromised
by the CMP composition of the present invention.
* * * * *