Title: Particle forming methods
Abstract: A particle forming method includes feeding a first set of precursors to a first energy application zone. Energy is applied to the first set of precursors in the first energy application zone effective to react and form solid particles from the first set of precursors. The application of any effective energy to the solid particles is ceased, and the solid particles and a second set of precursors are fed to a second energy application zone. Energy is applied to the second set of precursors in the second energy application zone effective to react and form solid material about the solid particles from the second set of precursors. At least one precursor is fed to at least one of the first and second energy application zones as a liquid. Other aspects are contemplated.
Patent Number: 6,977,097 Issued on 12/20/2005 to Doan
| Inventors:
|
Doan; Trung Tri (Boise, ID)
|
| Assignee:
|
Micron Technology, Inc. (Boise, ID)
|
| Appl. No.:
|
626791 |
| Filed:
|
July 23, 2003 |
| Current U.S. Class: |
427/212; 75/336; 75/345; 432/409; 432/410; 432/411; 427/213.3; 427/215; 427/216; 427/217; 204/157.41 |
| Intern'l Class: |
B24B 001/00; B05D 005/00; B05D 007/00; B01J 013/02; B22F 001/00 |
| Field of Search: |
75/336,345
205/157.41
423/409,410,411
427/212,213.3,215,216,217
|
References Cited [Referenced By]
U.S. Patent Documents
| 3453782 | Jul., 1969 | Hagelüken et al.
| |
| 3650714 | Mar., 1972 | Farkas.
| |
| 4314525 | Feb., 1982 | Hsu et al.
| |
| 4505720 | Mar., 1985 | Gabor et al.
| |
| 4585671 | Apr., 1986 | Kitagawa et al.
| |
| 4642227 | Feb., 1987 | Flagan et al.
| |
| 4883521 | Nov., 1989 | Shimizu et al.
| |
| 4994107 | Feb., 1991 | Flagan et al.
| |
| 5405648 | Apr., 1995 | Hermann.
| |
| 5514350 | May., 1996 | Kear et al.
| |
| 5525191 | Jun., 1996 | Maniar et al.
| |
| 5695617 | Dec., 1997 | Graiver et al.
| |
| 5770126 | Jun., 1998 | Singh et al.
| |
| 5814152 | Sep., 1998 | Thaler.
| |
| 5846310 | Dec., 1998 | Noguchi et al.
| |
| 5876490 | Mar., 1999 | Ronay.
| |
| 5876683 | Mar., 1999 | Glumac et al.
| |
| 5958348 | Sep., 1999 | Bi et al.
| |
| 6103393 | Aug., 2000 | Kodas et al.
| |
| 6254928 | Jul., 2001 | Doan.
| |
| 6270395 | Aug., 2001 | Towery et al.
| |
| 6464740 | Oct., 2002 | Towery et al.
| |
| 6471930 | Oct., 2002 | Kambe et al.
| |
| 6630433 | Oct., 2003 | Zhang et al.
| |
| 6726990 | Apr., 2004 | Kumar et al.
| |
| 2002/0003225 | Jan., 2002 | Hampden-Smith et al.
| |
Other References
Luce et al., Laser Synthesis of Nanometric Silica Powders, 4 Nanostructured
Materials, No. 4, pp. 403-408 (Elsevier Science Ltd. 1994).
Strutt et al., Synthesis of Polymerized Praceramic Nanoparticle Powders by
Laser Irradiation of Metalorganic Precursors, 1 Nanostructured Materials, pp.
21-25 (Pergamon Press 1992).
|
Primary Examiner: Eley; Timothy V.
Attorney, Agent or Firm: Wells St. John P.S.
Parent Case Text
This is a continuation of application Ser. No. 09/717,477, filed Nov. 20, 2000.
Claims
1. A particle forming method comprising:
feeding a first set of precursors to a first energy application zone;
first applying energy to the first set of precursors in the first energy application
zone effective to react and form solid particles from the first set of precursors;
ceasing application of any effective energy to the solid particles and feeding
the solid particles and a second set of precursors to a second energy application zone;
second applying energy to the second set of precursors in the second energy application
zone effective to react and form solid material about the solid particles from
the second set of precursors;
at least one precursor being fed to at least one of the first and second energy
application zones as a liquid.
2. The method of claim 1 wherein the first and second applied energies are of
a same type.
3. The method of claim 1 wherein the first and second applied energies are different types.
4. The method of claim 1 wherein at least one of the first and second applied
energies comprises laser energy.
5. The method of claim 1 wherein at least one of the first and second applied
energies comprises a combustion flame.
6. The method of claim 1 wherein at least one of the first and second applied
energies comprises a plasma flame.
7. The method of claim 1 wherein at least one of the first and second applied
energies comprises photosynthesis.
8. The method of claim 1 wherein the first and second energy application zones
are different.
9. The method of claim 1 wherein the first and second energy application zones
are the same.
10. The method of claim 1 wherein the first and second sets of precursors are
different, the second applying forming a solid material coating over the solid
particles which is different from material of the solid particles formed in the
first applying.
11. The method of claim 10 wherein one of said solid material or material of
the solid particles formed in the first applying is electrically conductive and
the other of said solid material or material of the solid particles formed in the
first applying is electrically insulative.
12. The method of claim 10 wherein said solid material is harder than the material
of the solid particles formed in the first applying.
13. The method of claim 10 wherein said solid material is softer than the material
of the solid particles-formed in the first applying.
14. The method of claim 10 wherein the first and second sets of precursors share
at least one common precursor.
15. The method of claim 10 wherein the solid material coating and the material
of the solid particles formed in the first applying comprise different nitrides.
16. The method of claim 10 wherein the first and second sets of precursors each
comprise NH
3, and the solid material coating and the material of the
solid particles formed in the first applying comprise different nitrides.
17. The method of claim 10 wherein the first and second sets of precursors do
not share any common precursor.
18. The method of claim 10 wherein the material of the solid particles formed
in the first applying comprises SiO
2, and the solid material coating
comprises an elemental metal.
19. The method of claim 10 wherein the material of the solid particles formed
in the first applying comprise SiO
2, and the solid material coating
comprises elemental tungsten.
20. The method of claim 1 further comprising forming a chemical mechanical polishing
slurry using the solid particles after the second applying as at least a portion
of a solid abrasive material within the slurry.
21. A particle forming method comprising:
providing a reaction flow path comprising a plurality of energy application zones;
feeding a first set of precursors to a first in sequence of the energy application
zones along the reaction flow path;
applying energy to the first set of precursors in the first in sequence of the
energy application zones effective to react and form solid particles from the first
set of precursors;
feeding the solid particles and a second set of precursors to a subsequent in
sequence of the energy application zones along the flow path;
feeding an inert purge gas to the reaction flow path intermediate the first in
sequence and the subsequent in sequence energy application zones; and
applying energy to the subsequent in sequence of the energy application zones
effective to react and form solid material about the solid particles from the second
set of precursors.
22. The method of claim 21 wherein the applied energies are of a same type.
23. The method of claim 21 wherein the applied energies are different types.
24. The method of claim 21 wherein at least one of the applied energies comprises
laser energy.
25. The method of claim 21 wherein at least one of the applied energies comprises
a combustion flame.
26. The method of claim 21 wherein at least one of the applied energies comprises
a plasma flame.
27. The method of claim 21 wherein at least one of the applied energies comprises photosynthesis.
28. The method of claim 21 wherein the inert purge gas is exhausted from the
reaction flow path prior to the subsequent in sequence energy application zone.
29. The method of claim 28 wherein the inert purge gas is exhausted from the
reaction flow path prior to feeding the second set of precursors to the reaction
flow path.
30. The method of claim 21 wherein the inert purge gas flows through the subsequent
in sequence energy application zone.
Description
TECHNICAL FIELD
This invention relates to particle forming methods, laser pyrolysis particle
forming methods, to chemical mechanical polishing slurries, and to chemical mechanical
polishing processes.
BACKGROUND OF THE INVENTION
Chemical mechanical polishing is one technique utilized to process the outer
surface of various layers formed over a semiconductor wafer. One principal use
of chemical mechanical polishing is to render an outer wafer surface of a layer
or layers to be more planar than existed prior to starting the polishing. Only
some or all of the outermost layer being polished might be removed during such
a process.
In chemical mechanical polishing, both the wafer and the pad which polishes the
wafer are typically caused to rotate, typically in opposite directions during the
polishing action. A liquid slurry is received intermediate the wafer and the polishing
pad. The slurry comprises a liquid solution, typically basic, and a solid abrasive
grit material, typically constituting particles of a consistent size (i.e., within
5 nanometers of a typical selected size from around 25 to 100 nanometers in diameter).
The action of the liquid solution and abrasive grit within the slurry intermediate
the wafer pad and wafer imparts removal of outer wafer layers utilizing both chemical
and mechanical actions.
One particular goal in the development of chemical mechanical polishing slurries
is the provision of particles of substantially uniform size. As identified above,
the typical individual particle size of chemical mechanical polishing slurries
is less than about 100 nanometers. Manufactured materials of this fine size are
commonly referred to as nanomaterials or nanoparticles. Such materials find use
in polishing processes and materials other than chemical mechanical polishing,
for example in batteries and in chemical reaction catalysts. Such materials have
historically been fabricated using combustion flame synthesis methods, such as
for example described in U.S. Pat. No. 5,876,683 to Glumac et al. More recently,
laser synthesis of nanoparticles is also gaining interest, such as described in
U.S. Pat. No. 5,695,617 to Graiver et al.,
Laser Synthesis of Nanometric Silica
Powders, by M. Luce et al., and
Synthesis of Polymerized Preceramic Nanoparticle
Powders by Laser Irradiation of Metalorganic Precursors, by P. R. Strutt et
al., which are hereby incorporated by reference.
It would be desirable to improve upon the laser synthesis methods, and to produce
improved chemical mechanical polishing slurries independent of the method fabrication.
SUMMARY
The invention comprises particle forming methods including laser pyrolysis particle
forming methods, chemical mechanical polishing slurries, and chemical mechanical
polishing processes. In but one preferred implementation, a laser pyrolysis particle
forming method includes feeding a first set of precursors to a first laser application
zone. Laser energy is applied to the first set of precursors in the first laser
application zone effective to react and form solid particles from the first set
of precursors. Application of any effective laser energy to the solid particles
is ceased and the solid particles and a second set of precursors are fed to a second
laser application zone. Laser energy is applied to the second set of precursors
in the second laser application zone effective to react and form solid material
about the solid particles from the second set of precursors.
In one implementation, a particle forming method includes feeding a first set
of precursors to a first energy application zone. Energy is applied to the first
set of precursors in the first energy application zone effective to react and form
solid particles from the first set of precursors. Application of any effective
energy to the solid particles is ceased and the solid particles and a second set
of precursors are fed to a second energy application zone. Energy is applied to
the second set of precursors in the second energy application zone effective to
react and form solid material about the solid particles from the second set of
precursors. Preferably, at least one of the first and second applied energies comprises
laser energy.
In one implementation, a chemical mechanical polishing slurry comprises liquid
and abrasive solid components. At least some of the abrasive solid component comprises
individually non-homogeneous abrasive particles.
In one implementation, a chemical mechanical polishing process includes rotating
at least one of a semiconductor substrate and polishing pad relative to the other.
A chemical mechanical polishing slurry is provided intermediate the substrate and
pad, and the substrate is polished with the slurry and pad during the rotating.
The chemical mechanical polishing slurry comprises liquid and abrasive solid components.
At least some of the abrasive solid component comprises individually non-homogeneous
abrasive particles.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are described below with reference
to the following accompanying drawings.
FIG. 1 is a diagrammatic depiction of a laser pyrolysis particle forming method
in accordance with an aspect of the invention.
FIG. 2 is a diagrammatic sectional view of a chemical mechanical polishing slurry
abrasive particle.
FIG. 3 is a diagrammatic representation of an alternate laser pyrolysis particle
forming method in accordance with an aspect of the invention.
FIG. 4 is a diagrammatic view of an exemplary system used in a chemical mechanical
polishing process in accordance with an aspect of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This disclosure of the invention is submitted in furtherance of the constitutional
purposes of the U.S. Patent Laws "to promote the progress of science and useful
arts" (Article 1, Section 8).
A laser pyrolysis particle forming method is indicated generally with reference
numeral
10. Such comprises a reaction flow path
12 having a beginning
end
14 and a product collection end
16. Reaction flow path
12
comprises at least first and second spaced laser application zones
18 and
20, respectively. A pair of first precursor inlets
22 and
24
are provided to reaction flow path
12 proximate beginning end
14
in advance of first laser application zone
12. A pair of second precursor
inlets
26 and
28 are provided to reaction flow path
12 between
first laser application zone
18 and second laser application zone
20.
A pair of inert gas inlets
30 and
32 are also provided intermediate
first laser application zone
18 and second laser application zone
20.
Such are preferably provided for injection of purging gas at this point in the
flow path, as will be described below. More or fewer precursor or inert inlets
could of course be provided.
Reaction flow path end
16 includes a suitable trap
34 for
collecting the formed particles. Unreacted precursor material, purge and/or carrier
gases are expelled via an exhaust
36.
At least one precursor is fed through one of first inlets
22 and
24
to reaction flow path
12 in advance of first laser application zone
18.
The precursor or precursors are preferably provided as a gas. In a particular example,
where for example SiO
2 particles are to be formed, example reactive
flow gases for lines
22 and
24 include a silane such as dichlorosilane,
and O
2, respectively. An example flow rate range for the dichlorosilane
is from about 100 sccm to about 10 slm, with an example flow rate for the O
2
also being from about 100 sccm to about 10 slm. Temperature and pressure
are preferably maintained within the reaction flow path outside of first and second
spaced laser application zones
18 and
20 such that reaction of gases
therein does not occur.
The one or more precursors fed from precursor inlets
22 and
24
are fed along reaction flow path
12 to first laser application zone
18.
The dichlorosilane and oxygen in this example comprise a first set of precursors
which is fed to first laser application zone
18. Laser energy is applied
in first laser application zone
18 effective to react and form solid particles
from the at least one precursor fed from at least one of first inlets
22
and
24. An example preferred pressure is 200 mTorr, with preferred temperature
being ambient and not controlled. The particles formed are exemplified in FIG.
1 by the illustrated specks or dots materializing in laser application zone
18.
An example laser is the commercial PRC-Oerlikon 1500 W fast-axial-flow CO
2
laser, such as described in the Luce et al. article referred to in the Background
section of this document. Other lasers, including excimer lasers, are also of course
utilizable, with KrF, ArF and Xe lasers being but only three additional examples.
Any suitable power can be chosen effective to provide suitable energy to cause
a reaction and produce particles, and could be optimized by the artisan depending
upon gas flow rate, desired particle size, etc. The material of the particles formed
utilizing the example dichlorosilane and O
2 feed gases will predominately
comprise SiO
2.
Such provides but one example process of first applying laser energy to a first
set of precursors in a first laser application zone effective to react and form
solid particles from the first set of precursors. Alternate processing is of course
contemplated. For example, and by way of example only, precursors could be injected
as liquid, and/or directly into the laser application zone as opposed to in advance
thereof as depicted and described relative to the most preferred embodiment.
The formed solid particles and any unreacted gas are fed from first laser application
zone
18 along reaction flow path
12 to between the first and second
spaced laser application zones
18 and
20, respectively. Such provides
but one example of ceasing application of any reaction effective laser energy to
the solid particles after their initial formation in first laser application zone
18. At least one precursor is fed through at least one of second precursor
inlets
26 and
28 into reaction flow path
12 between first
and second laser application zones
18 and
20 having the solid particles
flowing therein.
The precursor or precursors fed from at least one of second inlets
26
and
28 and the solid particles are fed along reaction flow path
12
to second laser application zone
20. Such provides but one example of feeding
the solid particles and a second set of precursors to a second laser application
zone. Laser energy is applied in second laser application zone
20 effective
to react and form solid material about the solid particles from the at least one
precursor fed from at least one of second inlets
26 and
28. Such
is shown in FIG. 1 by the enlarged or grown particles appearing within second laser
application zone
20.
The precursors provided from one or both of first inlets
22 and
24
can be the same as that provided from one or both of second precursor inlets
26
and
28, effectively forming substantially homogeneous solid particles at
the conclusion of applying laser energy in second laser application zone
20.
In effect in this example embodiment, the first formed particles in first laser
application zone
18 are subsequently coated in a separate laser application
zone
20 with the same material, effectively layering and growing particles
which are substantially individually homogeneous throughout. Application of at
least two and perhaps more laser pyrolysis steps for forming the particles might
result in more uniform size and shaped particles than might otherwise occur in
a single laser application process.
Alternately by way of example, the first and second sets of precursors
can be provided to be different, with the second depicted laser energy application
forming a solid material coating over the solid particles which is different from
material of the solid particles formed in first laser application zone
18.
Such might be utilized to provide optimized solid particles having different property
outer and inner materials, for example making the outer coating material or materials
harder or softer than the inner or initial material of the solid particles formed
in first laser application zone
18.
By way of example only, and continuing with the above example where SiO
2
particles are formed in first laser application zone
18, the subsequently
formed solid material coating the particles as formed in second laser application
zone
20 might comprise an elemental metal, such as elemental tungsten. For
example, one or more precursors could be fed into reaction flow path
12
from multiple inlets
26 and
28 to provide suitable reactive precursor
materials, preferably in the form of gases, for feeding to second laser application
zone
20. For example, a mixture of WF
6 and an effective amount
of H
2 could be fed as a mixture from each of inlets
26 and
28,
which would react in second laser application zone
20 to coat the initially
formed SiO
2 particles with elemental tungsten.
Where the first and second sets of precursors are different, it might be desirable
to provide an inert purge gas, such as N
2 or Ar, from inlets
30
and
32 between first and second laser application zones
18 and
20
in advance of precursor inlets
26 and
28. Such purging might be desired
to effectively dilute any unreacted remaining gases which have flowed through first
laser application zone
18 to prevent reaction of the same in second laser
application zone
20 where one or more discrete different material coatings
are desired on the outside of the initially formed particles. Such gases flowing
from first laser application zone
18 and any purged gases injected by inlets
30 and
32 might be exhausted (not shown) from reaction flow path
12 in advance of subsequent precursor injection at at least one of
26
and
28, or alternately flow in a diluted manner through second laser application
zone
20.
The first and second sets of precursors might or might not share at least one
common precursor. The above described example is one where no precursor material
is common to the first and second sets. Consider alternately by way of example
only a process wherein it is desired to form inner and outer layers of a particle
which comprise different nitrides. For example, consider forming the inner layer
to comprise TiN, and forming the outer layer to comprise a harder WN material.
NH
3 could be utilized as one of the precursor gases for supplying the
nitrogen component of the formed nitrides in both the first and second sets of
precursors. In one example, an abundance of NH
3 could be fed to reaction
flow path
12 in advance of first laser application zone
18. An example
additional first precursor gas flowing from one or both of first inlets
22
and
24 would be TiCl
4. The TiCl
4 and NH
3 would
desirably react to form TiN particles in first laser application zone
18.
Unreacted NH
3 and reaction byproducts would flow from first laser application
zone
18, and could be combined with WF
6 flowing out of one or
both of second inlets
26 and
28. The WF
6 and NH
3would
desirably react within second laser application zone
20 to form an outer
coating of WN over the initially formed TiN particles. Additional NH
3 might
be added to reaction flow path
12 intermediate first laser application zone
18 and second laser application zone
20 through one or both of inlets
26 and
28.
More than two laser application zones or laser applications might also be utilized.
Regardless, the processes most preferably are utilized to produce nanomaterials,
whereby the ultimately formed solid particles have a maximum diameter of no greater
than 1 micron, and more preferable no greater than 100 nanometers.
FIG. 2 depicts an individually formed non-homogeneous particle
50. Such
comprises an inner exemplary portion
52 formed within first laser application
zone
18, and an outer coating
54 formed in second laser application
zone
20.
The resultant formed particles are collected in trap
34 (FIG. 1), with
remaining precursor inert or carrier gases being exhausted via line
36 FIG. 1.
The above described processing depicted the first and second laser application
zones as being different and spaced from one another along a reaction flow path.
Alternate considered processing in accordance with the invention is shown in FIG.
3, whereby the first and second laser application zones comprise the same zones
in different first and second applications of laser energy to the same or different
precursors. Like numerals from the first described embodiment are utilized where
appropriate, with differences being indicated with the suffix "a", or with different numerals.
Method
10a in FIG. 3 differs from that depicted in FIG. 1 by
provision of a single laser application zone
18, and provision of a recycle
stream
60 from trap
34 back to immediately in advance of laser application
zone
18. In a preferred process in accordance with the FIG. 3 methodology,
particles would initially be formed and collected in trap
34. Thereafter,
the particles would be flowed back to reaction flow path
12a in advance
of laser application zone
18, preferably in one or more discrete single
batches for uniformity in size control, and combined with the same or different
precursors for subsequent coating thereof. Further alternately and less preferred,
pulsed laser application might occur in a single or multiple laser application
zone(s) relative to one or more precursor gases to sequentially form multiple layered
or coated particles.
Also contemplated in accordance with aspects of the invention is application
of energy other than laser energy to effect some or all of the particle formation.
For example, one or both of energy application zones
18 and
20 might
comprise energy application sources other than laser. By way of example only, such
might include a combustion flame, a plasma flame, photosynthesis such as UV light
application, and other heat energy such as passing the precursors/forming particles
through a pass-through furnace. Further, energy application zones
18 and
20 might comprise the same or different energy types.
The above described produced solid particles are preferably utilized in forming
a chemical mechanical polishing slurry at least a portion of which contains such
particles as the solid abrasive material within the slurry. Thereby, a preferred
chemical mechanical polishing slurry in accordance with the invention comprises
liquid and abrasive solid components. At least some of the abrasive solid components
comprise individually non-homogeneous abrasive particles produced by the above
described or prior art or yet to be developed methods. Such particles might be
characterized by two distinct material layers or more layers. Preferably, one of
the two layers will envelop the other.
Slurries in accordance with the invention can be utilized in chemical mechanical
polishing processes in accordance with another aspect of the invention, and as
generally described with reference to FIG. 4. An exemplary system shown in diagrammatic
or schematic form for conducting a chemical mechanical polishing method in accordance
with the invention is indicated generally with reference numeral
60. Such
comprises a polishing table or platen
62 having a polishing pad
64
received thereatop. A wafer carrier
66 is juxtaposed in opposing relation
relative to polishing pad
64. A workpiece
68, typically in the form
of a semiconductor wafer, is received by wafer carrier
66. A slurry injection
port
70 is positioned to emit fluid onto pad
64 to be received between
pad
64 and wafer
68 during polishing. Wafer carrier
66 and
polishing table
62 are typically mounted for independent controllable rotation
relative to one another. One or more wafer carrier head assemblies might be utilized
for a single polishing table, and be mounted for translational movement as well
relative to table
62. The above describes but one very diagrammatic exemplary
depiction of a chemical mechanical polishing system within which a method of the
invention might be utilized.
In accordance with this aspect of a chemical mechanical polishing process in
accordance
with the invention, at least one of a semiconductor substrate and polishing pad
are rotated relative to the other. A chemical mechanical polishing slurry is provided
intermediate the substrate and pad, and the substrate is polished with the slurry
and pad during the rotating. The chemical mechanical polishing slurry comprises
liquid and abrasive solid components. At least some of the abrasive solid component
comprises individually non-homogeneous abrasive particles, such as for example
described above and producible in accordance with the inventive and other processes.
In compliance with the statute, the invention has been described in language
more
or less specific as to structural and methodical features. It is to be understood,
however, that the invention is not limited to the specific features shown and described,
since the means herein disclosed comprise preferred forms of putting the invention
into effect. The invention is, therefore, claimed in any of its forms or modifications
within the proper scope of the appended claims appropriately interpreted in accordance
with the doctrine of equivalents.
*
