U.S. patent application number 11/272844 was filed with the patent office on 2007-05-17 for apparatus and methods for slurry cleaning of etch chambers.
Invention is credited to Ian Martin Davis, David P. Laube.
Application Number | 20070111642 11/272844 |
Document ID | / |
Family ID | 37758692 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070111642 |
Kind Code |
A1 |
Davis; Ian Martin ; et
al. |
May 17, 2007 |
Apparatus and methods for slurry cleaning of etch chambers
Abstract
Described are methods of cleaning debris from semiconductor etch
chambers or chamber components, one method comprising directing
atomized abrasive slurry onto at least some internal surfaces of
such a chamber or chamber components. Apparatus for carrying out
the methods are also described.
Inventors: |
Davis; Ian Martin;
(Chandler, AZ) ; Laube; David P.; (Mesa,
AZ) |
Correspondence
Address: |
THE BOC GROUP, INC.
575 MOUNTAIN AVENUE
MURRAY HILL
NJ
07974-2064
US
|
Family ID: |
37758692 |
Appl. No.: |
11/272844 |
Filed: |
November 14, 2005 |
Current U.S.
Class: |
451/38 ;
451/99 |
Current CPC
Class: |
B24C 5/04 20130101; B24C
11/005 20130101; H01L 21/67051 20130101; B24C 7/0038 20130101; B24C
3/325 20130101 |
Class at
Publication: |
451/038 ;
451/099 |
International
Class: |
B24C 1/00 20060101
B24C001/00 |
Claims
1. An apparatus for removing deposits from semiconductor etch
chamber components without damaging the etch chamber components or
coatings thereon comprising: (a) an atomizing head having an
abrasive slurry inlet, an atomizing fluid inlet, and an atomized
abrasive slurry outlet, the atomizing head adapted to draw an
abrasive slurry into the abrasive slurry inlet by negative pressure
and to produce an atomized abrasive slurry; (b) an abrasive slurry
container fluidly connected to the abrasive slurry inlet and
defining a space for the abrasive slurry comprising water and
abrasive particles; and (c) a source of atomizing fluid fluidly
connected to the atomizing fluid inlet.
2. The apparatus of claim 1, wherein the source of atomizing fluid
is selected from a membrane unit, an absorption unit, a cryogenic
unit, a container of fluid, a compressor, a pipeline, a gas
cabinet, and combinations thereof.
3. The apparatus of claim 1 wherein the source of atomizing fluid
comprises a source of one or more inert gases and combinations
thereof.
4. The apparatus of claim 3 wherein the source of inert gas is
selected from sources of nitrogen, argon, air, nitrogen enriched
air, noble gases other than argon, and combinations and mixtures
thereof.
5. The apparatus of claim 1, wherein the atomizing head comprises a
venturi.
6. The apparatus of claim 1, wherein the abrasive slurry container
comprises a mixing device.
7. The apparatus of claim 1 comprising a pressure regulator adapted
to adjust pressure of the atomizing fluid.
8. The apparatus of claim 7 wherein the pressure regulator is
adapted to adjust pressure of the atomized abrasive slurry.
9. An apparatus for removing deposits from semiconductor etch
chamber components without damaging the etch chamber components or
coatings thereon comprising: (a) a venturi having an abrasive
slurry inlet, a gas inlet, and an atomized abrasive slurry outlet,
the venturi adapted to draw an abrasive slurry into the abrasive
slurry inlet by negative pressure and to produce an atomized
abrasive slurry; (b) an abrasive slurry container fluidly connected
to the abrasive slurry inlet and defining a space for the abrasive
slurry comprising water and abrasive particles; (c) a source of gas
fluidly connected to the gas inlet; and (d) an agitator adapted to
maintain the abrasive slurry well dispersed.
10. A method comprising: flowing an atomizing fluid through an
atomizing head having an abrasive slurry inlet; drawing abrasive
slurry into the abrasive slurry inlet by negative pressure; and
directing the atomized abrasive slurry onto at least some internal
surfaces of a semiconductor etching chamber.
11. The method of claim 10 wherein the abrasive slurry comprises
abrasive particles selected from silicon dioxide, calcium oxide,
pumice, aluminum oxide, titanium oxide, zirconium oxide, and
combinations of thereof.
12. The method of claim 10 wherein the step of drawing abrasive
slurry into the abrasive slurry inlet by negative pressure
comprises drawing the abrasive slurry from an abrasive slurry
container into the abrasive slurry inlet and dispensing atomized
abrasive slurry through an atomized abrasive slurry outlet.
13. The method of claim 10 comprising the step of controlling
pressure of the atomized abrasive slurry exiting the atomizing
head.
14. The method of claim 13 wherein said controlling pressure
comprises controlling pressure at a pressure ranging from about 25
to about 150 psig.
15. The method of claim 10 comprising the step of controlling
density of the atomized abrasive slurry.
16. The method of claim 15 comprising controlling density from
about 0.01 gm/cc to about 0.20 gm/cc.
17. The method of claim 12 comprising controlling momentum of the
atomized abrasive slurry exiting the atomizing head.
18. The method of claim 17 comprising controlling momentum of the
atomized abrasive slurry at momentum ranging from about 100,000
gm-cm/sec to about 300,000 gm-cm/sec.
19. The method of claim 12 comprising the step of maintaining the
abrasive slurry in the abrasive slurry container in well dispersed
state.
20. The method of claim 12 comprising the step of controlling
composition of the abrasive slurry in the container.
Description
FIELD OF THE INVENTION
[0001] The invention is directed to cleaning apparatus and methods,
particularly, but not limited to, apparatus and methods for
cleaning products and chambers made during semiconductor
manufacturing.
RELATED ART
[0002] Removal of contaminants from etch chamber components
traditionally uses carbon dioxide pellet blasting, abrasive bead
blasting, solvents, strong oxidizers, inorganic acids/bases or high
temperature thermal decomposition. Depending on the
contaminant/substrate combination, these produce marginal results
in contaminant removal and providing high cleanliness surfaces for
chamber reuse. These methods may also damage the substrate during
the cleaning process particularly when using conventional
mechanical cleaning methods for anodized and coated aluminum
substrates. More recent designs of chamber components make use of
plasma sprayed dielectric coatings such as Al.sub.2O.sub.3,
ZrO.sub.2, and Y.sub.2O.sub.3. These coatings are applied to
ceramic and anodized aluminum substrates where coating adhesion is
marginal at best and are easily damaged during cleaning due to the
aggressive nature of conventional abrasive blasting techniques.
[0003] Clearly there is a real need for effective removal of
deposits from all surfaces used during the process of creating a
semiconductor wafer without degrading or damaging the substrate or
coating surface.
SUMMARY OF THE INVENTION
[0004] In accordance with the present invention, apparatus and
methods are presented which overcome or reduce deficiencies
associated with previous apparatus and methods in cleaning
semiconductor etching chambers and components.
[0005] A first aspect of the invention is an apparatus, one
apparatus comprising: [0006] (a) an atomizing head adapted to
produce an atomized abrasive slurry, the head having an abrasive
slurry inlet, an atomizing fluid inlet, and an atomized abrasive
slurry outlet; [0007] (b) an abrasive slurry container fluidly
connected to the abrasive slurry inlet and defining a space for a
slurry comprising water and abrasive particles; and [0008] (c) a
source of atomizing fluid fluidly connected to the atomizing fluid
inlet.
[0009] Apparatus within the invention include those wherein the
container may have an agitator adapted to maintain the abrasive
particles well dispersed. "Well dispersed", as used herein, means
that the abrasive slurry may be a homogenous mixture of all
ingredients. The source of atomizing fluid may be selected from a
membrane unit, an absorption unit, a cryogenic unit, a container of
fluid, a compressor, a pipeline, a gas cabinet, and combinations
thereof. The source of atomizing fluid may comprise a source of one
or more inert gases and combinations thereof. The inert gas may be
selected from any gas that would be considered inert for the
cleaning process, including, but not limited to, nitrogen, argon,
air, nitrogen enriched air, noble gases other than argon, and
combinations thereof. The atomizing head may comprise a venturi.
Apparatus may comprise a pressure regulator adapted to adjust
pressure of the atomizing fluid entering the atomizing head. The
pressure regulator may be adapted to adjust pressure of the
atomized abrasive slurry exiting the atomizing head.
[0010] Another aspect of the invention is a method of cleaning, one
method comprising directing an atomized abrasive slurry onto at
least some internal surfaces of a semiconductor etching chamber or
chamber components. Methods of the invention include those wherein
the directing comprises controlling pressure of the atomized
abrasive slurry. The pressure may generally be controlled within a
pressure ranging from about 25 to about 150 psig. Pressures higher
than 150 psig may be used if necessary to remove debris and the
underlying substrate is not damaged. The density of the atomized
abrasive slurry may need to be reduced; pressures lower than 25
psig may not be able to provide the desired cleaning efficiency,
but may be used if the density of the atomized abrasive slurry is
increased. Methods of the invention include those methods wherein
the directing step comprises controlling density of the atomized
abrasive slurry. Several ways are available for controlling density
of the atomized slurry, including adding more liquid to the
abrasive slurry, reducing the amount and/or density of the abrasive
particles in the abrasive slurry, reducing the density of the
atomizing fluid and/or increasing its flow rate, and combinations
of these. The density of the atomized abrasive slurry may be
controlled within a density ranging from about 0.01 gm/cc to about
0.2 gm/cc. Other methods of the invention include controlling
momentum of the atomized abrasive slurry exiting the atomizing
head. Methods of the invention include controlling momentum of the
atomized abrasive slurry at momentum ranging from about 100,000
gm-cm/sec to about 300,000 gm-cm/sec. Other methods may include
maintaining the abrasive slurry in the abrasive slurry container in
well dispersed state, and methods wherein the composition of the
abrasive slurry in the container is controlled.
[0011] The various aspects of the invention will become more
apparent after review of the following brief description of the
drawings, detailed description, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The manner in which the objectives of the invention and
other desirable characteristics can be obtained is explained in the
following description and attached drawings in which:
[0013] FIGS. 1 and 2 are schematic side elevation views of first
and second apparatus embodiments according to the present
invention.
[0014] It is to be noted, however, that the appended drawings are
not to scale and illustrate only typical embodiments of this
invention, and are therefore not to be considered limiting of its
scope, for the invention may admit to other equally effective
embodiments.
DETAILED DESCRIPTION
[0015] In the following description, numerous details are set forth
to provide an understanding of the present invention. However, it
will be understood by those skilled in the art that the present
invention may be practiced without these details and that numerous
variations or modifications from the described embodiments may be
possible.
[0016] All phrases, derivations, collocations and multiword
expressions used herein, in particular in the claims that follow,
are expressly not limited to nouns and verbs. It is apparent that
meanings are not just expressed by nouns and verbs or single words.
Languages use a variety of ways to express content. The existence
of inventive concepts and the ways in which these are expressed
varies in language-cultures. For example, many lexicalized
compounds in Germanic languages are often expressed as
adjective-noun combinations, noun-preposition-noun combinations or
derivations in Romanic languages. The possibility to include
phrases, derivations and collocations in the claims is essential
for high-quality patents, making it possible to reduce expressions
to their conceptual content, and all possible conceptual
combinations of words that are compatible with such content (either
within a language or across languages) are intended to be included
in the used phrases.
[0017] In accordance with the present invention, apparatus and
methods are presented which overcome or reduce problems associated
with previous methods and apparatus. Apparatus of the invention
comprise an atomizing head functioning to produce an atomized
abrasive slurry. The head comprises an abrasive slurry inlet, an
atomizing fluid inlet, and an atomized abrasive slurry outlet. The
atomizing head may include any internal volume capable of producing
an atomized abrasive slurry, including a venturi, a
converging-diverging nozzle, a converging nozzle, and other nozzle
configurations.
[0018] In simplified terms there are three major methods for
achieving atomization of a liquid or slurry: [0019] 1. rotating cup
atomization involves shredding the fluid with the air of a moving
mechanical element. [0020] 2. in mechanical atomization the fluid
to be atomized is compressed to very high pressures (15 to 30
bars), thus imparting to it a high potential energy converted to
kinetic energy when released to atmospheric pressure. This energy
results in shearing of the liquid when it is brought into contact
with the exterior atmosphere and thus results in the formation of
droplets. [0021] 3. gaseous-fluid-assisted atomization can be used
to arrive at a similar result while achieving a saving on high
pressures (2 to 6 bars).
[0022] Apparatus of the present invention are concerned with the
third category of atomization. In simplified terms one can
distinguish two types of gaseous-fluid-assisted atomization
according to whether the liquid to be atomized and atomizing fluid
are brought into contact inside or outside the atomizer head. These
types may be referred to as internal atomization and external
atomization. Both types are useful in the present invention.
[0023] Internal atomization is characterized by confinement of the
liquid and atomizing fluid in a contacting chamber. The mode of
introduction of the two fluids into this chamber can vary
considerably and has a direct influence on the characteristics of
the atomized slurry that exits from the chamber. Likewise, the
internal geometry of this chamber (overall volume, vanes for
producing rotation, number and diameters of the inlet and outlet
orifices, and so forth) also affects the specific characteristics
of the liquid/atomizing fluid mixture. This mode of atomization
generally affords an excellent quality of atomization, that is, an
atomized slurry composed of very small slurry droplets with a very
narrow droplet size distribution about these small diameters. At a
given liquid delivery rate, this atomization quality is naturally a
function of the atomizing fluid delivery rate employed and the
pressure level prevailing in the interior of the atomizing
chamber.
[0024] For external atomization, where contact between the two
phases takes place outside of any confining enclosure, the atomized
slurry is created mainly by shearing of the jet of liquid slurry by
the atomizing fluid. The geometry of the outlets for the two fluids
completely determines the quality of the atomization, and droplet
size analysis of the drops resulting from the contact may show a
relatively wide diameter distribution (simultaneous-presence of
small and large droplets).
[0025] FIG. 1 is a schematic side elevation view of one apparatus
embodiment 100 according to the present invention, comprising an
atomizing head 2 having an atomizing fluid inlet 4, an abrasive
slurry inlet 6, and an atomized abrasive slurry outlet 8. Atomizing
head 2 may be made from any suitable material or combination of
materials, such as metal, plastic, and combinations thereof.
Suitable metals include aluminum, stainless steels, such as 304
stainless steel. The stainless steel may be electropolished, but
this is not a requirement of the invention. In embodiment 100, the
internal flow channels include a converging nozzle 10, a parallel
throat section 12, and a diverging nozzle 14. Throat 12 includes in
this embodiment an inlet port or orifice 16 for abrasive slurry,
which is drawn into throat 12 by negative pressure caused by
flowing fluidizing fluid. Abrasive slurry may be drawn up from one
or more abrasive slurry containers 20, and head 2 may have one or
more fluid connections to one or more sources of fluidizing fluid
18. Although this particular flow configuration represents a
venturi, the invention is not so limited.
[0026] There are numerous options in the design of each particular
atomizing head, and all are considered foreseeable alternative
embodiments within the present invention. For example, in head 2 of
FIG. 1, atomizing fluid inlet may be comprised of one, two, or more
than two inlet orifices, as may abrasive inlet orifice 16. For
example, it may be advantageous to place an inlet port or orifice
16a opposite of orifice 16.
[0027] FIG. 2 is a schematic side elevation view of another
apparatus embodiment 200 according to the present invention,
similar to embodiment 100 illustrated in FIG. 1, comprising an
atomizing head 22 having an atomizing fluid inlet 4, an abrasive
slurry inlet 6, and an atomized abrasive slurry outlet 8. However
in embodiment 200, the internal flow channels include a more
streamlined converging-diverging nozzle 24, 28, and a throat 26.
Throat 26 also includes in this embodiment an inlet port or orifice
16 for abrasive slurry, which is drawn into throat 26 by negative
pressure caused by flowing fluidizing fluid. Abrasive slurry may be
drawn up from one or more abrasive slurry containers 20, and head 2
may have one or more fluid connections to one or more sources of
fluidizing fluid 18.
[0028] Another component of apparatus of the invention is an
abrasive slurry container fluidly connected to the abrasive slurry
inlet of the atomizing head. The container functions to define a
space for a slurry comprising water, abrasive particles, and other
optional ingredients, depending on the particular cleaning task,
for example the type and quantity of debris or deposits to be
removed, the underlying substrate composition and hardness, and the
properties of any substrate coating, such as a refractory or
dielectric coating.
[0029] The abrasive slurry container may be under atmospheric
pressure, at a slight vacuum, or at a pressure above atmospheric,
although the pressure in the container is not critical. The
container may be closed or open to the atmosphere. If the container
is at a pressure less than or greater than atmospheric the
container will necessarily be manufactured to withstand these
conditions. The container may comprise an outer shell with a
bladder arrangement, where abrasive slurry is held inside the
bladder. Air or other fluid may be used to force slurry out of the
bladder, and a vacuum may assist loading the bladder with the
abrasive slurry.
[0030] The configuration of the abrasive slurry container is not
critical, as long the abrasive particles are able to be kept
suspended, or reasonably so, in the container. There may be
occasions when there are more abrasive particles than required for
a particular task, in which case not all abrasives particles will
need to be suspended. Some may be allowed to settle out to the
bottom of the container until needed. The materials of construction
of the slurry container are not critical. The container may be
metal, plastic, or some combination thereof. A refractory or
ceramic container may even be used, and a liner may be used. The
liner may be a ceramic or plastic material. Suspension aids may be
used. These may be chemical, mechanical or combination thereof. A
mechanical suspension aide may comprise one or more stirring or
agitating device. A chemical suspension aide may comprise one or
more suspension aide chemicals. Examples of these latter are
discussed further herein.
[0031] Apparatus of the invention may comprise a source of
atomizing fluid fluidly connected to the atomizing fluid inlet. The
source of atomizing fluid is selected from a membrane unit, an
absorption unit, a cryogenic unit, a container of fluid, a
compressor, a pipeline, a gas cabinet, and combinations thereof.
The source of atomizing fluid may comprise a source of one or more
inert gases and combinations thereof. If used, the inert gas may be
selected from sources of nitrogen, argon, air, nitrogen enriched
air, noble gases other than argon, and combinations and mixtures
thereof. The atomizing fluid need not be a pure gas. For example,
the atomizing fluid may be air, or nitrogen generated by a membrane
separation unit producing nitrogen enriched air. Most nitrogen
membranes generate nitrogen having about 90 to 95 percent nitrogen,
although higher purity is possible by using multiple membrane units
connects in series or in cascade fashion. Purities of higher than
95 percent may not be necessary. The dryness of the gas used may be
a concern, for if the atomizing fluid is a gas and the gas has
considerable water or other liquid, the composition of the atomized
abrasive slurry might be different from that in the abrasive slurry
container, possibly resulting in inconsistent results. The source
of atomizing fluid is fluidly connected to the atomizing head by
one or more conduits, which may include one or more pressure
regulators adapted to adjust pressure of the atomizing fluid as it
enters the atomizing head. If the amount of abrasive slurry feed to
the atomizing head is maintained relatively constant, the pressure
regulator may be adapted to adjust pressure of the atomized
abrasive slurry as well. The pressure of the source of atomizing
fluid may be any pressure required to atomize a particular slurry
and perform the cleaning function. The pressure of the source of
atomizing fluid may be controlled, such as by use of a gas cabinet,
or it may be taken from a pipeline where there is little control
over the pressure of the atomizing fluid in the pipeline.
[0032] In operation, methods of the invention include directing an
atomized abrasive slurry onto at least some internal surfaces of a
semiconductor etching chamber. The methods include generating the
atomized abrasive slurry by flowing an atomizing fluid through an
atomizing head, as described. Generating the atomized abrasive
slurry may comprise controlling pressure of the atomized abrasive
slurry exiting the atomizing head at a pressure ranging from about
25 to about 150 psig. The generating may comprise controlling
density of the atomized abrasive slurry to a density ranging from
about 0.01 gm/cc to about 0.2 gm/cc. It is desirous to control the
momentum of the atomized abrasive slurry as it contacts the
workpiece. The momentum of the atomized abrasive slurry at the
workpiece may be controlled by controlling the momentum of the
atomized abrasive slurry as it exits the atomizing head. The
momentum of the atomized abrasive slurry exiting the atomizing head
may be controlled with in a range of from about 100,000 gm-cm/sec
to about 300,000 gm-cm/sec. The momentum of the atomized abrasive
slurry as it exits the atomizing head may be controlled by
adjusting the pressure of the atomizing fluid as it enters the
atomizing head, the amount of slurry entering the atomizing head,
the density of the abrasive slurry, or any combination of
these.
[0033] The abrasive slurry may be maintained in a well-dispersed
state in the abrasive slurry container. As noted previously, in the
context of the invention this means the abrasive slurry may be a
homogenous mixture of all ingredients.
[0034] Abrasive particles useful in the invention may be selected
from those commonly used in the abrasive art, however, the abrasive
particles (size and composition) will be chosen with the degree of
surface roughness, coating thickness change, and adhesion
properties in mind. In choosing an appropriate abrasive particle,
characteristics such as hardness, compatibility with the intended
workpiece, particle size, reactivity with the workpiece, as well as
heat conductivity may be considered.
[0035] The composition of abrasive particles useful in the
invention can be divided into two classes: natural abrasives and
manufactured abrasives. Examples of natural abrasives include:
diamond, corundum, emery, garnet, buhrstone, chert, quartz,
sandstone, chalcedony, flint, quartzite, silica, feldspar, pumice
and talc. Examples of manufactured abrasives include: boron
carbide, cubic boron nitride, fused alumina, ceramic aluminum
oxide, heat treated aluminum oxide, alumina zirconia, glass,
silicon carbide, iron oxides, tantalum carbide, cerium oxide, tin
oxide, titanium carbide, synthetic diamond, manganese dioxide,
zirconium oxide, and silicon nitride.
[0036] Abrasive particles useful in the invention typically and
preferably have a particle size ranging from about 0.1 micrometer
to about 1500 micrometers, more preferably ranging from about 0.1
micrometer to about 1300 micrometers. The abrasive particles
preferably have an average particle size ranging from about 0.1
micrometer to about 700 micrometers, more preferably ranging from
about 1 to about 150 micrometers, particularly preferably from
about 1 to about 80 micrometers. It is preferred that abrasive
particles used in the invention have a Moh's hardness of at least
8, more preferably above 9; however, for specific applications,
softer particles may be used.
[0037] The term "abrasive particle" includes agglomerates of
individual abrasive particles. An abrasive agglomerate is formed
when a plurality of abrasive particles are bonded together with a
binder to form a larger abrasive particle which may have a specific
particulate structure. The plurality of particles which form the
abrasive agglomerate may comprise more than one type of abrasive
particle and a binder.
[0038] Generally, fillers are inorganic particulate matter which
comprise apparatus which are substantially inert or non-reactive
with respect to the surface acted upon by the abrasive.
Occasionally, however, active (i.e. reactive) fillers are used,
sometimes referred to in the abrasives art as grinding aids. These
fillers interact beneficially with the workpiece during use. In
particular, it is believed in the art that the grinding aid may
either 1) decrease the friction between the abrasive particles and
the workpiece being abraded, 2) prevent the abrasive particle from
"capping", i.e. prevent metal particles from becoming welded to the
tops of the abrasive particles, 3) decrease the interface
temperature between the abrasive particles and the workpiece or 4)
decrease the required grinding force.
[0039] Grinding aids encompass a wide variety of different
materials and can be inorganic or organic based. Examples of
chemical groups of grinding aids useful in this invention include
waxes, organic halide compounds, halide salts and metals and their
alloys. The organic halide compounds will typically break down
during abrading and release a halogen acid or a gaseous halide
compound. Examples of such materials include chlorinated waxes like
tetrachloronaphthalene, pentachloronaphthalene; and polyvinyl
chloride. Examples of halide salts include sodium chloride,
potassium cryolite, sodium cryolite, ammonium cryolite, potassium
tetrafluoroborate, sodium tetrafluoroborate, silicon fluorides,
potassium chloride, magnesium chloride. Examples of metals include,
tin, lead, bismuth, cobalt, antimony, cadmium, iron titanium. Other
miscellaneous grinding aids include sulfur, organic sulfur
compounds, graphite and metallic sulfides. It is also within the
scope of this invention to use a combination of different grinding
aids and in some instances this may produce a synergistic effect.
The above mentioned examples of grinding aids is meant to be a
representative showing of grinding aids, and it is not meant to
encompass all grinding aids.
[0040] Grinding aids may be used in abrasive slurries useful in the
invention in amounts ranging from about 0.1 to about 10 dry weight
percent, more preferably from about 0.5 to about 5.0 weight
percent, based on total weight of slurry. If non-reactive fillers
are employed they may be used up to 50 dry weight percent.
[0041] Abrasive slurries useful in the invention may contain any
number of conventional additives such as one or more additional
components, such as, for example, plasticizer, chelating agent, pH
modifier, defoamer, foaming agent, reinforcing polymer, anti-freeze
agent, suspension aid, bactericide, fingicide, and/or
thickener.
[0042] Abrasive slurries of the invention may be prepared by mixing
abrasive particles having known particle size ranging from 5
micrometers and known particle size distribution ranging from 1-75
micrometers with deionized water, and optionally other materials,
to achieve slurry density ranging from about 0.01 gm/cc to about
0.2 gm/cc. The slurry may be mixed for 20 minutes at 1200 rpm using
a high shear mixer, and the mixer may be left on during use of the
slurry, but at lower rpm, in order to maintain a well dispersed
slurry.
[0043] The abrasive slurry may be converted into an atomized spray
using an atomizing head having a venturi, similar to that
illustrated schematically in FIG. 1. As an example, the atomizing
head may be manufactured out of aluminum, and may have one or more
slurry inlet orifices of diameter of about 1 cm, one or more air
(atomizing fluid) inlet orifices of diameter of 1 cm, and one or
more atomized slurry outlet orifices having a diameter of 2 cm. The
abrasive slurry may be fed to the atomizing head through a flexible
stainless steel tube, the abrasive slurry drawn into the atomizing
head by air entering the atomizing head at a pressure of about 100
psig. The atomized slurry emerges from the atomizing head at a
pressure of about 50 psig. The slurry tank may be maintained
stirred as mentioned above. The slurry tank may be at atmospheric
pressure and room temperature, although these conditions are simply
convenient and not required. The atomized slurry may be directed at
dielectric-coated surfaces of an etch chamber having deposits of
silicon, silicon carbide, and other debris on the dielectric
surface. The atomized slurry may be directed at the surfaces at a
90.degree. angle, although other angles may be used. The pre-test
roughness (Ra) of the dielectric surfaces are measured, as well as
the post-test roughness after 30 seconds of contacting the atomized
slurry to the dielectric surfaces. "Ra" is a common measure of
roughness used in the abrasives industry. "Ra" is defined as the
arithmetic mean of the departures of the roughness profile from the
mean line. Ra may be measured with a profilometer probe, which has
a diamond tipped stylus. In general, the lower the Ra value, the
smoother or finer the workpiece surface finish. The profilometer
known under the trade designation Perthen M4P may be used.
Thickness of coatings may be determined by microsection techniques
known in the art.
[0044] Apparatus and methods of the present invention may to be
used to effectively remove debris from surfaces of semiconductor
etching chambers. Although only a few exemplary embodiments of this
invention have been described in detail above, those skilled in the
art will readily appreciate that many modifications are possible in
the exemplary embodiments without materially departing from the
novel teachings and advantages of this invention. Accordingly, all
such modifications are intended to be included within the scope of
this invention as defined in the following claims.
* * * * *