U.S. patent application number 10/990649 was filed with the patent office on 2005-05-12 for apparatus for deposition of diamond like carbon.
This patent application is currently assigned to Advanced Energy Industries, Inc.. Invention is credited to Amann, Michael S., Kishinevsky, Michael, Quinn, Colin, Shabalin, Andrew.
Application Number | 20050098118 10/990649 |
Document ID | / |
Family ID | 22441906 |
Filed Date | 2005-05-12 |
United States Patent
Application |
20050098118 |
Kind Code |
A1 |
Amann, Michael S. ; et
al. |
May 12, 2005 |
Apparatus for deposition of diamond like carbon
Abstract
Apparatus to achieve both more uniform and particle free DLC
deposition is disclosed which automatically cycles between modes to
effect automatic removal of carbon-based buildups or which provides
barriers to achieve proper gas flow involves differing circuitry
and design parameter options. One ion source may be used in two
different modes whether for DLC deposition or not through automatic
control of gas flow types and rates and through the control of the
power applied to achieve maximum throughput or other desired
processing goals. Arcing can be controlled and even permitted to
optimize the overall results achieved.
Inventors: |
Amann, Michael S.;
(Loveland, CO) ; Kishinevsky, Michael; (Fort
Collins, CO) ; Shabalin, Andrew; (Fort Collins,
CO) ; Quinn, Colin; (Fort Collins, CO) |
Correspondence
Address: |
SANTANGELO LAW OFFICES, P.C.
125 SOUTH HOWES, THIRD FLOOR
FORT COLLINS
CO
80521
US
|
Assignee: |
Advanced Energy Industries,
Inc.
Fort Collins
CO
|
Family ID: |
22441906 |
Appl. No.: |
10/990649 |
Filed: |
November 16, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10990649 |
Nov 16, 2004 |
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10246493 |
Sep 17, 2002 |
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6818257 |
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10246493 |
Sep 17, 2002 |
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09551169 |
Apr 17, 2000 |
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6451389 |
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60129850 |
Apr 17, 1999 |
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Current U.S.
Class: |
118/723CB ;
216/66; 427/249.7; 427/523; 427/585 |
Current CPC
Class: |
C23C 14/0605 20130101;
H01J 27/08 20130101; C23C 14/221 20130101; C23C 14/564
20130101 |
Class at
Publication: |
118/723.0CB ;
427/249.7; 427/523; 427/585; 216/066 |
International
Class: |
C23C 016/00; H01L
021/338 |
Claims
What is claimed is:
1-21. (canceled)
22. A deposition system for coating Diamond-Like-Carbon on
substrates comprising: a. a chamber; b. a vacuum system connected
to said chamber; c. an ion source positioned within said chamber;
d. a hydrocarbon-containing gas supply connected in the vicinity of
said ion source; e. a hydrocarbon beam creation power application
element to which said ion source is responsive; f. a substrate
position element adjacent to said chamber; g. a diamond-like-carbon
coating element which is responsive to said ion source; h. a
carbon-reacting gas supply to which said ion source is responsive;
i. a reactive discharge creation power application element to which
said ion source is responsive and which acts to create at least
some carbon reaction product within said chamber; and j. a carbon
reaction product removal element connected to said chamber.
23. A deposition system for coating Diamond-Like-Carbon on
substrates as described in claim 22 wherein said ion source
alternatingly comprises a deposition-appropriate ion beam source
and a carbon-reactive ion beam source.
24. A deposition system for coating Diamond-Like-Carbon on
substrates as described in claim 22 wherein said ion source
alternatingly comprises a current-proportional-to-voltage source
and a current-independent-of-volta- ge source.
25. A Diamond-Like-Carbon repetitive process system as described in
claim 23 wherein said hydrocarbon beam creation power application
element comprises an arc avoidance element and wherein said
reactive discharge creation power application element comprises an
arc permission element.
26. A Diamond-Like-Carbon repetitive process system as described in
claim 23 wherein said hydrocarbon beam creation power application
element comprises a power application element selected from a group
consisting of: a power application element which applies a voltage
of from about 100 volts to about 1000 volts, a power application
element which applies a current of from about 0.1 amperes to about
20 amperes, a power application element which applies a voltage of
from about 100 volts to about 1000 volts and a current of from
about 0.1 amperes to about 20 amperes, a power application element
which applies a voltage of from about 100 volts to about 2000
volts, a power application element which applies a voltage of from
about 1000 volts to about 2000 volts, a power application element
which applies a current of from about 0.5 amperes per linear meter
of ion source length to about 15 amperes per linear meter of ion
source length and wherein said reactive discharge creation power
application element comprises a power application element selected
from a group consisting of: a power application element which
applies a voltage of from about 100 volts to about 600 volts, a
power application element which applies a power level that is at
least about twice the level of power applied to said hydrocarbon
beam creation power application element, a power application
element which applies a power level that is at least about three
times the level of power applied to said hydrocarbon beam creation
power application element, a power application element which
applies a power level that is at least about four times the level
of power applied to said hydrocarbon beam creation power
application element, a power application element which applies a
power level that is at least several times the level of power
applied to said hydrocarbon beam creation power application
element, a power application element which acts for a time short
compared to the time during which said hydrocarbon beam creation
power application element, a power application element which
applies a power level which ramps up, a power application element
which applies a power level which ramps up over a time period of
from about 0.1 seconds to about 4 seconds, and a power level which
permits arcs to occur such arc supplying less than about 20
millijoules of energy during their occurrence.
27. A Diamond-Like-Carbon repetitive process system as described in
claim 22 wherein said reactive discharge creation power application
element comprises a maximum power element.
28. A Diamond-Like-Carbon repetitive process system as described in
claim 22 and further comprising a timer element to which said ion
source is responsive.
29. A Diamond-Like-Carbon repetitive process system as described in
claim 28 wherein carbon-based material forms within said chamber at
a varying rate and wherein said timer element causes action of said
reactive discharge creation power application element before said
varying rate substantially increases.
30. A Diamond-Like-Carbon repetitive process system as described in
claim 28 wherein said timer element comprises an optimal processing
throughput timer element.
31. A Diamond-Like-Carbon repetitive process system as described in
claim 28 wherein said timer element sets a period so as to activate
said reactive discharge creation power application element and to
create at least some carbon reaction product within said chamber at
times of processing selected from a group consisting of: processing
to achieve less than about 100 .ANG. of Diamond-Like-Carbon,
processing to achieve less than about 500 .ANG. of
Diamond-Like-Carbon, processing to achieve less than about 1,000
.ANG. of Diamond-Like-Carbon, processing to achieve less than about
5,000 .ANG. of Diamond-Like-Carbon, processing to achieve less than
about 10,000 .ANG. of Diamond-Like-Carbon, processing to achieve
coating of less than about 10 computer disks, processing to achieve
coating of less than about 20 computer disks, processing to achieve
coating of less than about 40 computer disks, and processing to
achieve coating of less than about 100 computer disks.
32. A Diamond-Like-Carbon repetitive process system as described in
claim 28 wherein said timer element sets a period so as to activate
said reactive discharge creation power application element for a
duration selected from a group consisting of: about 1 second, about
2 seconds, about 4 seconds, about a processing time of said
substrate, and about a processing time of said substrate less a
purge time of a gas environment.
33. A Diamond-Like-Carbon repetitive process system as described in
claim 28 wherein said timer element sets a period so as to activate
said reactive discharge creation power application element for a
duration of about a processing time of a substrate less a purge
time of a gas environment and wherein said repetitive process
system further comprises a substrate discard element.
34. A Diamond-Like-Carbon repetitive process system as described in
claim 22 and further comprising a substrate isolation element.
35. A Diamond-Like-Carbon repetitive process system as described in
claim 22 wherein said ion source positioned within said chamber
comprises a material processing ion beam source selected from a
group consisting of: a linear ion source, a cold cathode ion
source, a non-hot electron emitter ion source, a closed drift ion
source, a multi-cell cold cathode anode-layer closed drift ion
source, a linear cold cathode anode-layer closed drift ion source,
a single cell ion source, an anode-layer ion source, and an
end-hall ion source.
36. A Diamond-Like-Carbon repetitive process system as described in
claim 22 wherein said hydrocarbon-containing gas supply comprises a
gas supply selected from a group consisting of: an acetylene gas
supply, an ethylene gas supply, a propane gas supply, a butane gas
supply, a pentane gas supply, a hexane gas supply, or combination
thereof, and wherein said carbon-reacting gas supply comprises a
gas supply selected from a group consisting of: an oxygen gas
supply, oxygen and argon gas supply, and a noble gas and a reactive
gas supply.
37. A Diamond-Like-Carbon repetitive process system as described in
claim 26 wherein said hydrocarbon-containing gas supply comprises a
gas supply selected from a group consisting of: an acetylene gas
supply, an ethylene gas supply, a propane gas supply, a butane gas
supply, a pentane gas supply, a hexane gas supply, or combination
thereof, and wherein said carbon-reacting gas supply comprises a
gas supply selected from a group consisting of: an oxygen gas
supply, oxygen and argon gas supply, and a noble gas and a reactive
gas supply.
38-60. (canceled)
61. A Diamond-Like-Carbon repetitive process system comprising: a.
a chamber; b. a repetitive substrate feed element in the vicinity
of said chamber; c. an ion source positioned within said chamber;
d. a gas supply in the vicinity of said ion source; e. a
diamond-like-carbon coating element which is responsive to said ion
source; f. an affirmative avoidance element which affirmatively
avoids the formation of carbon-based particles on said substrate
within said chamber; and g. a substrate removal element in the
vicinity of said chamber.
62. A Diamond-Like-Carbon repetitive process system as described in
claim 61 wherein said affirmative avoidance element which
affirmatively avoids the formation of carbon-based particles within
said chamber comprises an automatic operation element.
63. A Diamond-Like-Carbon repetitive process system as described in
claim 62 wherein said automatic operation element comprises an
automatic power supply operation element to which said ion source
is responsive.
64. A Diamond-Like-Carbon repetitive process system as described in
claim 62 wherein said automatic operation element comprises an
automatic gas supply operation element to which said gas supply is
responsive.
65. A Diamond-Like-Carbon repetitive process system as described in
claim 63 wherein said automatic operation element further comprises
an automatic gas supply operation element to which said gas supply
is responsive.
66. A Diamond-Like-Carbon repetitive process system as described in
claim 62 wherein said diamond-like-carbon coating element achieves
repetitive processing selected from a group consisting of:
processing to achieve a cumulative amount of greater than about 500
.ANG. of Diamond-Like-Carbon, processing to achieve a cumulative
amount of greater than about 1000 .ANG. of Diamond-Like-Carbon,
processing to achieve a cumulative amount of greater than about
3,000 .ANG. of Diamond-Like-Carbon, processing to achieve a
cumulative amount of greater than about 10,000 .ANG. of
Diamond-Like-Carbon, processing to achieve coating of greater than
about 20 computer disks, processing to achieve coating of greater
than about 40 computer disks, and processing to achieve coating of
greater than about 100 computer disks.
67. A Diamond-Like-Carbon repetitive process system comprising: a.
a chamber; b. a repetitive substrate feed element in the vicinity
of said chamber; c. a Diamond-Like-Carbon process system
comprising: i. an ion source positioned within said chamber; ii. a
hydrocarbon-containing gas supply to which said ion source is
responsive; and iii. a diamond-like-carbon coating element which is
responsive to said ion source; d. an automatic interruption element
to which said Diamond-Like-Carbon process system is responsive; e.
an automatic carbon-based material elimination element connected to
said chamber; and f. an automatic restart element to which said
Diamond-Like-Carbon process system is responsive.
68. A Diamond-Like-Carbon repetitive process system as described in
claim 67 wherein said Diamond-Like-Carbon process system comprises
a deposition system as described in claim 22.
69. A Diamond-Like-Carbon repetitive process system as described in
claim 67 wherein said Diamond-Like-Carbon process system further
comprises a beam creation power application element to which said
ion source is responsive.
70. A Diamond-Like-Carbon repetitive process system as described in
claim 69 wherein said automatic interruption element to which said
Diamond-Like-Carbon process system is responsive comprises: a. an
automatic power supply operation element to which said beam
creation power application element is responsive; and b. an
automatic gas supply operation element to which said
hydrocarbon-containing gas supply is responsive.
71. A Diamond-Like-Carbon repetitive process system as described in
claim 69 and further comprising a gas purge element connected to
said chamber.
72. A Diamond-Like-Carbon repetitive process system as described in
claim 69 and further comprising a substrate removal element in the
vicinity of said chamber.
73. A Diamond-Like-Carbon repetitive process system as described in
claim 72 wherein said repetitive substrate feed element in the
vicinity of said chamber comprises: a. a desired substrate feed;
and b. a desired substrate avoidance element.
74. A Diamond-Like-Carbon repetitive process system as described in
claim 67 wherein said automatic elimination element connected to
said chamber comprises: a. a reactive gas supply to which said ion
source is responsive and which causes the formation of at least
some carbon reaction product; and b. a carbon reaction product gas
purge element connected to said chamber.
75. A Diamond-Like-Carbon repetitive process system as described in
claim 69 wherein said automatic elimination element connected to
said chamber comprises a second beam creation power application
element to which said ion source is responsive.
76. A Diamond-Like-Carbon repetitive process system as described in
claim 67 wherein said automatic elimination element connected to
said chamber comprises an arc permission element.
77. A Diamond-Like-Carbon repetitive process system as described in
claim 76 wherein said automatic elimination element connected to
said chamber further comprises a maximum power element.
78. A Diamond-Like-Carbon repetitive process system as described in
claim 67 wherein said automatic elimination element connected to
said chamber comprises a timer element.
79. A Diamond-Like-Carbon repetitive process system as described in
claim 78 wherein said timer element comprises an optimal processing
throughput timer element.
80. A Diamond-Like-Carbon repetitive process system as described in
claim 78 wherein said timer element sets a period so as to activate
said automatic interruption element at processing times selected
from a group consisting of: processing to achieve less than about
100 .ANG. of Diamond-Like-Carbon, processing to achieve less than
about 500 .ANG. of Diamond-Like-Carbon, processing to achieve less
than about 1,000 .ANG. of Diamond-Like-Carbon, processing to
achieve less than about 5,000 .ANG. of Diamond-Like-Carbon,
processing to achieve less than about 10,000 .ANG. of
Diamond-Like-Carbon, processing to achieve coating of less than
about 10 computer disks, processing to achieve coating of less than
about 20 computer disks, processing to achieve coating of less than
about 40 computer disks, and processing to achieve coating of less
than about 100 computer disks.
81. A Diamond-Like-Carbon repetitive process system as described in
claim 78 wherein said timer element sets a period so as to
accomplish elimination for a duration selected from a group
consisting of: about 1 second, about 2 seconds, about 4 seconds,
about a processing time of said substrate, and about a processing
time of said substrate less a purge time of a gas environment.
82. A Diamond-Like-Carbon repetitive process system as described in
claim 78 wherein said timer element sets a period so as to
accomplish elimination for a duration of about a processing time of
a substrate less a purge time of a gas environment and further
comprising a discardable substrate positioned responsive to said
repetitive substrate feed element.
83-94. (canceled)
95. A material processing ion beam system comprising; a. a chamber;
b. a vacuum system connected to said chamber; c. a low impedance
discharge mode material processing ion source positioned within
said chamber; d. a gas supply in the vicinity of said low impedance
discharge mode material processing ion source; e. a beam creation
power application element to which said low impedance discharge
mode material processing ion source is responsive.
96. A material processing ion beam system as described in claim 95
wherein said beam creation power application element to which said
low impedance discharge mode material processing ion source is
responsive comprises a power supply which applies from about 100
volts to about 600 volts to said material processing ion beam
source.
97. A material processing ion beam system as described in claim 95
wherein said beam creation power application element to which said
low impedance discharge mode material processing ion source is
responsive comprises a high impedance current source.
98. A material processing ion beam system as described in claim 97
wherein said gas supply in the vicinity of said low impedance
discharge mode material processing ion source comprises a low
impedance discharge mode material processing ion flux gas
supply.
99. A material processing ion beam system as described in claim 95
wherein said low impedance discharge mode material processing ion
source positioned within said chamber comprises a
Diamond-Like-Carbon configured ion source.
100. A material processing ion beam system as described in claim 95
wherein said low impedance discharge mode material processing ion
source positioned within said chamber comprises a material
processing ion beam source selected from a group consisting of: a
linear ion source, and a single-cell anode-layer ion source.
101. A material processing ion beam system as described in claim 95
wherein said low impedance discharge mode material processing ion
source positioned within said chamber comprises a material
processing ion beam source selected from a group consisting of: a
cold cathode ion source, a non-hot electron emitter ion source, a
closed drift ion source, a multi-cell cold cathode anode-layer
closed drift ion source, a linear cold cathode anode-layer closed
drift ion source, a single cell ion source, an anode-layer ion
source, and an end-hall ion source.
102. A material processing ion beam system as described in claim 95
wherein said gas supply in the vicinity of said low impedance
discharge mode material processing ion source comprises a reactive
gas supply.
103. A material processing ion beam system as described in claim
102 wherein said a reactive gas supply comprises a gas supply
selected from a group consisting of: an oxygen gas supply, an
oxygen and argon gas supply, and a noble gas and a reactive gas
supply.
104. A material processing ion beam system as described in claim
103 and further comprising at least one carbon-containing surface
positioned within said chamber.
105. A material processing ion beam system as described in claim
104 wherein said low impedance discharge mode material processing
ion source positioned within said chamber comprises a
Diamond-Like-Carbon configured ion source.
106-117. (canceled)
Description
[0001] This patent application is a division application and claims
priority from and the benefit of U.S. patent application Ser. No.
10/246,493, filed Sep. 17, 2002, published on Apr. 24, 2003, and
issuing on Nov. 16, 2004 as U.S. Pat. No. 6,818,257, said
application itself claiming priority to U.S. patent application
Ser. No. 09/551,169, filed Apr. 17, 2000, now issued as U.S. Pat.
No. 6,451,389, which application claims priority to U.S. Patent
Application No. 60/129,850 entitled "Apparatus and Method for
Uniform Deposition of a Diamond Like Carbon on a Substance" filed
Apr. 17, 1999, each above-mentioned application hereby incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] This invention generally relates to deposition of thin films
using ion beams and the like. Specifically, the invention has
application to deposition of diamond-like carbon (DLC) films where
requirements for the deposited films include low particle
contamination and high uniformity.
[0003] Ion beam deposition of diamond-like films is known and has
been studied by different authors. Enisherova et al in Material
Science and Engineering B46 (1997), pp. 137-140, incorporated by
reference here into, investigated properties of DLC deposited on a
substrate using an industrial cold cathode ion source. Baldwin et
al in U.S. Pat. No. 5,616,179, incorporated by reference here into,
disclosed a DLC deposition method using an end-Hall ion source.
Further, even though not particularly relevant to the present
invention, to the extent it may be helpful background understanding
of some other types of processing can be obtained from other
publications, such as U.S. Pat. Nos. 5,427,669, 5,535,906, 5645698,
5718813, and 5747935, each to the assignee of the present
invention.
[0004] Computer hard disk protective coatings and some other
applications are sensitive to particle contamination of the
surface. Those skilled in the art know that particle contamination
problems can accompany virtually all carbon-containing plasma
applications. Carbon material in such plasmas can tend to
conglomerate into particles that are precipitated or formed on
most, if not all, surfaces in the vacuum chamber, including the
substrate surface. The particles often grow in size with time and,
as mentioned, can find their way to the substrate surface. In
addition, accumulated carbon material inside the ion source can
change discharge parameters and eventually may short circuit ion
source electrodes. While this may be tolerable in some
applications, in sensitive applications--such as the computer disk
processing mentioned above--particulate or carbon contamination is
not acceptable.
[0005] This can create a necessity to open the vacuum chamber on
regular basis and to remove carbon deposits from the ion source and
vacuum chamber wall. This maintenance can increase the downtime and
may result in lost productivity. It may also create variability in
processing. In such applications, the present invention can act to
virtually eliminate particle contamination without the need to open
the vacuum chamber for cleaning. In addition to producing
particle-free films, an additional benefit of the invention can be
the possibility of virtually maintenance-free operation of the ion
source itself.
[0006] One additional desire well known to those skilled in the art
is the uniformity of coating over the substrate surface. This
aspect is especially difficult in systems that process one
substrate at a time because it can be difficult to achieve particle
free coating and even uniform distribution of ion beams current
density and gas pressure over the substrate surface. As to the
latter aspect, a conventional way to achieve high uniformity can be
to move the substrate in front of the deposition source. This
movement is often present in in-line and carousel type coating
systems but in single substrate systems the movement of substrate
can complicate the process significantly and increase the cost of
equipment. Many times a complicated two-axis planetary pattern of
substrate movement needs to be used, as in the paper of Enisherova,
mentioned above.
[0007] Further, there is currently a desire in the disk industry to
find a replacement for currently used magnetron-based amorphous
carbon deposition systems. Such a replacement would preferably
deposit diamond-like-carbon and fit into existing equipment. It
would also not allow or require substrate movement during the
deposition process. The present invention achieves high uniformity
and particle free coating with stationary substrate by optimization
of the ion source design and utilization.
[0008] Perhaps surprisingly, the present invention provides
solutions to many problems in manners using technologies which
others might have had available. However, the fact that there was a
long felt but unsatisfied need for this type of invention while the
needed implementing arts and elements had long been available and
the fact that there was no full appreciation of the nature of the
problem by those skilled in the art each seem to show how the
invention is considerably more significant than simply a choice in
mode of operation or the like for these applications. The
significant inconvenience suffered by operators and the potentially
substantial attempts by those skilled in the art to overcome the
problems show the difficulties extant. Thus it appears that at
least some of these difficulties were because of a failure to
understand the problems to the degree now explained. Through
adoption of other, less economical solutions and the large degree
of improvement (rather than merely gradual steps), the invention
may be shown to present approaches which others acted to teach away
from. It may also indicate that the results of the invention would
be considered unexpected if initially viewed without the hindsight
of an exposure to this disclosure.
SUMMARY OF THE INVENTION
[0009] A method that is the subject of one embodiment of the
present invention can make use of the fact that some cold cathode
ion sources, such as the well-known multicell ion sources and
linear ion sources series manufactured by Advanced Energy
Industries, Inc., Fort Collins, Colo., are capable of running a
discharge in an oxygen-containing gas mixture or in pure oxygen.
The present inventors have found that a discharge can clean the ion
source and vacuum chamber surfaces from carbon and that periodical
application of a new mode of operation described herein, the
reactive cleaning cycle, can allow the deposition process to run
without adding any substantial particle contamination on the
substrate. This may even exist virtually indefinitely. The
discharge reactive cleaning cycle can also eliminate the need for
opening the vacuum chamber in order to remove carbon or the like
from the inside of the chamber and the ion source. Perhaps
surprisingly, in some situations it may be that the reactive
cleaning cycle time can be much shorter that the deposition
time.
[0010] Additionally, those skilled in the art also know that it is
difficult to achieve uniformity of the coating thickness over the
entire substrate surface when substrates are coated one at a time
by a wide ion beam, like in many hard disk coating machines. In the
apparatus used by Enisherova et al, the substrate was moved in
front of the ion source in a complicated planetary way during the
deposition to make the film more uniform. For many applications,
like hard disk protective coating, the substrate movement is not
practical or is prohibitively expensive. Therefore, there is a need
to achieve acceptable thickness uniformity with a stationary
substrate. Accordingly, in other embodiments, the present invention
discloses ways to optimize the apparatus design to achieve maximum
uniformity at given maximum ion source size.
[0011] Accordingly, it is an object of the invention to avoid or
minimize the effects of carbon or particle contamination in
sensitive coating processes. In keeping with this object it is a
goal to provide a system which acts automatically and thus without
a need to have an operator physically access the interior of the
chamber to address an undesirable condition.
[0012] In is also an object to provide coatings of higher quality
and of more uniformity than was previously done.
[0013] Yet another object is to provide a new mode of operation of
an ion source so that different types of processing may be
accomplished in a variety of contexts.
[0014] Naturally, other objects of the invention are disclosed
throughout other areas of the specification and claims. In
addition, the goals and objectives may apply either in dependent or
independent fashion to a variety of other goals and objectives in a
variety of embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a general schematic diagram of an apparatus for
one type of uniform deposition indicating the general relationship
between the component parts of the apparatus.
[0016] FIG. 2 is a general view of an AE LIS linear ion source.
[0017] FIG. 3 is a schematic diagram of a LIS linear ion
source.
[0018] FIG. 4 is a photograph of an AE MCIS-12 Multicell ion
source.
[0019] FIG. 5 is a cross sectional view of an MCIS Multicell ion
source.
[0020] FIG. 6 is a cross sectional view of an MCIS Multicell ion
source with radial gas flow barriers installed.
[0021] FIG. 7 is an isometric drawing of the exterior of one
apparatus showing the processing chamber with two ion sources
mounted.
[0022] FIG. 8 is a schematic diagram of an apparatus designed to
achieve particle-free coating according to the present
invention.
[0023] FIG. 9 is one example of a conceptual plot of carbon
formation in a chamber.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] As can be easily understood, the basic concepts of the
present invention may be embodied in a variety of ways. It involves
both processing techniques as well as devices to accomplish the
appropriate processing. In this application, each is disclosed as
part of the results shown to be achieved by the various devices and
methods described and as steps which are inherent to utilization.
In addition, while some devices are disclosed, it should be
understood that these not only accomplish certain methods but also
can be varied in a number of ways. Importantly, as to all of the
foregoing, all of these facets should be understood to be
encompassed by this disclosure.
[0025] One type of system is shown schematically in FIG. 8. As can
be seen, the involves some type of chamber (1) within which an
appropriate low pressure environment can be created. As is well
known, this is usually accomplished through some type of vacuum
system (3) connected in some way to the chamber (1). As may be
easily understood from the prior art, with the chamber may be
positioned some type of substrate (13) for processing. Without
limiting the applications, one type of substrate (13) which is of
particular importance is a computer disk such as for a hard drive
or the like. As is well understood, hard disks may be of any size,
and may be made out of aluminum, or glass, or any other solid
material. This material can thus be the substrate (13) which is to
be coated.
[0026] The coating (17), such as a diamond-like-carbon coating, can
be produced by some action of an ion source (2). (Two sources
could, of course be included if it were desired to coat both sides
of the substrate (13).) This ion source may act as an ion beam
source in which case an ion flux (12) is produced (as explained
later this term is intended to cover any dispersion of ions
regardless of the focusing or the "beam" character). The ion flux
(12) such as a beam is influenced in some manner by the
introduction of a gaseous substance, such as a gaseous beam
substance (4) usually at a specific location in the vicinity of the
ion source (2). By the proper selection of parameters and
substances, the ion source can thus serve as a material processing
ion source, that is a source which achieves a specific type of
processing. Two types of processing of importance to this preferred
embodiment are processing which achieves a diamond-like-carbon
coating on a substrate and processing which removes accumulated
carbon from chamber surfaces.
[0027] As is well known, the ion source (2) achieves its goals by
not only the application of a gaseous beam substance (4) inside or
in the vicinity of it by also the application of power to it. This
power may be supplied by a power application element (8). Power
application element (8) may supply power of such a character as to
serve as a beam creation power application element or the like or
it may, as discussed below, be of such a character as to serve as a
reactive discharge application element or the like. In achieving a
deposition appropriate beam, the source might have a first power
condition applied to it. This might typically produce a beam with
enough ions of the type of element(s) being deposited and have low
enough content of any reactive element that the ions can form
volatile or gaseous species containing the deposited element so the
net result of exposure of the substrate to the beam is some
material left on the surface of the substrate. Conversely, a
reactive-appropriate beam or discharge might be powered by a second
power condition which could, but need not always be typically
different from the first power condition. The reaction-appropriate
beam then may or may not be produced to contain reactive elements
but it might normally not contain material that has been deposited,
so that the net result would be the removal of a product and
potentially cleaning if desired.
[0028] As mentioned, the ion source (2) may or may not produce a
focused beam. If focused, the ions would travel in a collimated
fashion. If not, a diffuse beam might exist as the ion flux (12). A
diffuse beam or discharge would have a wide angular distribution.
As applicable to multi-cell ion sources it should be understood
that even in a high voltage or other more collimated mode, the
resultant ion migration could be divergent. For example, if each
cell produced a collimated beam but the resultant multicell ion
source beam consisted of multiple annular beamlets created in the
individual cells which were intentionally directed so that each
diverged, the resulting beam at some distance might becomes
smoother and similar to a truly diffuse beam. In general though,
each cell would have produced a more collimated beam than imagined
for a true diffuse discharge.
[0029] As is also known, the overall system, such as a
diamond-like-carbon process system (16) could serve to repetitively
process substrates in some manner. Movement of a substrate (13)
could be achieved by the use of some type of substrate position
element (5) which may act at any desired time in the overall
process. It should be understood that while this is shown as a
conveyer belt type of arrangement, such is for schematic purposes
only and a great variety of designs may be used. The substrate
position element (5) could serve as a repetitive substrate feed
element so that the ion source (2) would repetitively achieve or
form the desired processing as the repetitive substrate feed
element acted in harmony. For application using the
diamond-like-carbon processing mentioned and the carbon removal
processing mentioned, the substrate position element (5) might also
be arranged to serve by moving the substrate (13) through, into, or
near some type of substrate isolation element such as the ports
(14) as those skilled in the art readily understand. The substrate
position element (5) might also serve as a substrate removal
element similar to the design conceptually depicted in FIG. 8.
[0030] Of course, the ultimate goal is that of achieving some type
of processing, such as by permitting the ion source (2) and the
other elements to together serve as a diamond-like-carbon coating
element. This may be achieved by utilizing a hydrocarbon containing
gas as the gaseous beam substance (4). The hydrocarbon containing
gas would create a hydrocarbon containing gas environment typically
within the ion source (2) so that as a result of the ion source's
action, a deposition appropriate ion beam could be produced. In
this manner the arrangement would serve as a deposition-appropriate
ion beam source and the power application element (8) could serve
as a hydrocarbon beam creation power application element. As a
result of some interaction of these the result maybe a
diamond-like-carbon coating (17) on the substrate (13) to result in
a diamond-like-carbon coated substrate (18). As those skilled in
the art understand, the hydrocarbon containing gas may be pure or
it may be a mixture of a hydrocarbon gas and some other gas (noble
or not) as the application requires.
[0031] As mentioned, a great variety of different types of elements
can be used. This can include different types of ion sources (2).
Single- and multi-cell sources are of course possible. In the
claims a variety of the many possible types of sources appropriate
for this invention are listed. As can be seen in FIGS. 2 through 6,
some of these include an AE LIS linear ion source (FIG. 2), a
general linear ion source (FIG. 3), an AE MCIS-12 Multicell ion
source (FIG. 4), a different view of the MCIS (FIG. 5), and a
multicell ion source with radial gas flow barriers installed (FIG.
6). Cold cathode ion sources, non-hot electron emitter ion sources,
closed drift ion sources, multi-cell cold cathode anode-layer
closed drift ion sources, linear cold cathode anode-layer closed
drift ion sources, anode-layer ion sources, end-hall ion sources,
single cell sources, especially the AE Single Cell ion source (AE
SCIS), are among the many others possibly utilized.
[0032] As mentioned in the background section above, one of the
problems which has existed is the formation of carbon particles.
While in some applications, this may not be of particular concern,
in hard disk processing, as but one example, the formation of
carbon particles on the substrate can be completely unacceptable.
This unfortunate byproduct of DLC coating processes is perhaps most
appropriately characterized as the formation of any carbon based
material--other than the desired material such as a
diamond-like-carbon material. In observing the formation of carbon
based material, it has been noticed that in at least some
applications, the larger particles or higher number of particles
form at an increasing rate. Although not quantified experimentally,
this potentially could display a characteristic as shown
conceptually in FIG. 9, where it can be seen that at some point in
time, such as the point shown as item (21), the size, number, or
both of particles as shown by the curve (20) begins to vary at a
varying rate which begins to substantially increase.
[0033] As a significant aspect of this invention, it has been noted
that by acting before the varying rate begins to substantially
increase, the amount of time necessary to remove the particles--or
perhaps more accurately acting even before they truly begin to form
from a results perspective--the effects of carbon formation or
particle formation can be largely overcome. This can be set at a
variety of levels, but for the present systems, levels such as
listed in the claims or perhaps less than the amount of time
necessary to process about twenty computer disk substrates has been
shown to be very advantageous. Naturally, this can vary based upon
the situation, system, or processing being effected. Thus as shown,
defining the point in time for the action, item (21), as relative
to the initial average particle size or with reference to the
initial, clean chamber particle time or processing achieved is
possible.
[0034] Mentioned earlier with respect to the goals and objects of
the invention is the fact that the present invention can achieve
particle free coatings without a need for the traditional human
intervention or cleaning. The system can thus achieve uninterrupted
processing with total cumulative deposition depths which are far
greater--and perhaps infinite--as compared to the prior systems
which needed periodic cleaning. This can be accomplished by
automatically cycling between the reactive and deposition modes.
This cycling can be accomplished by a variety of power and gas
controls as follows. First, the type of gas to be applied can be
varied. Noteworthy is the fact that he last processed substrate
such as the last diamond-like-carbon coated substrate (18) would
usually need to be somehow isolated from the chamber area involved
(the reactive environment would typically ruin the substrate),
appropriate action could be taken. As to the gaseous beam substance
(4), such as a hydrocarbon containing gas, the action could be to
shutoff the gas. Processing would then of course be stopped, if not
stopped earlier. This could typically occur through an action of
some type of automatic gas supply operation element (15). Any
remaining hydrocarbon gas would then be purged by natural action of
the vacuum system (3) which would thus serve as a gas purge
element.
[0035] Similarly, and in any sequence, the power application
element (8) might be controlled to be shut off (perhaps even before
the action of the automatic gas supply operation element (15))
through control circuitry or programming such as the timer element
(11) or otherwise as those skilled in the art would readily
appreciate. This might also act to stop the deposition cycle and
stop the first power condition for the ion source.
[0036] Once the substrates were isolated (by coating, shielding,
movement or otherwise), and after the deposition process had
stopped, the automatic gas supply operation element (15) could then
be activated (or be continued to be activated) to introduce a
reactive gas (7) such as a carbon-reacting gas into the chamber.
The carbon reacting gas would create a different environment in or
near the ion source (2). Through circuitry or programming, the
second power condition might automatically begin and be applied at
some time. In this fashion the power application element (8) could
be controlled to serve as a reactive discharge creation power
application element. and the same deposition-appropriate ion beam
source might now begin to operate as a reactive discharge ion
source. The ion source (2) would thus generate a discharge which
was more appropriate for the removal of the carbon buildups that
might be present. This carbon-reactive discharge could act within
the chamber (1) to effect the processing of at least some
carbon-containing surface by causing a reaction with some of the
carbon-based material thereon. This reaction would preferably
create a carbon-containing material of a gaseous nature and which
could then be removed by the action of the gas purge element,
usually the vacuum system (3).
[0037] As can be immediately appreciated, the above processing
could be repeated sequentially at various times as appropriate to
the system and processing achieved. Some of the times and various
levels possible are set forth in the claims. Overall this
configuration could serve as an element which affirmatively avoided
carbon particle formation, or an affirmative avoidance element.
Further, by removing the gaseous reaction product as mentioned,
virtually virgin processing could be reinstituted. The entire
sequence could be automatically controlled by programming,
circuitry or the correct selection of elements to result in the
automatic alteration events or elements, the automatic stopping
events or elements, the automatic elimination events or elements,
the automatic interruption events or elements, the automatic
operation events or elements, and the automatic restart events or
elements mentioned.
[0038] Independent of the application mentioned above, it should be
understood that through the appropriate selection of the gas flows
and power conditions applied, the ion source (2) can act in two
entirely different modes. In the traditional mode, the ion current
generated produces the typical deposition-appropriate beam. This
may, but need not be the traditional, collimated beam. Here the
beam may be one in which the beam current is roughly proportional
to the voltage applied. In this traditional mode, the discharge
voltage is set by power supply and the discharge current depends on
the applied voltage and gas pressure. In other words, the power
applied usually acts as a voltage source with low impedance and ion
source functions as a high impedance current source. The higher the
voltage and the higher the gas pressure--the higher the current.
The ion source (2) acts as a high impedance current source and as a
current-proportional-to-voltage source.
[0039] The operational mode utilized in the other condition is
quite different. In fact, the ion source (2) essentially flips into
that different mode, the low impedance discharge mode. In this
mode, the material processing ion beam is actually a low impedance
discharge mode material processing ion flux. Here, the discharge
current is not so proportional to voltage. The power applied may
only control discharge current, and the discharge voltage may be
set by the ion source (2) itself. The voltage may not practically
change when current varies widely. Thus, the power application
element (8) may serve as a current source (high impedance) and the
ion source (2) as a low impedance voltage source. Notably, it is
now disclosed that either the deposition or reactive event can
exist in this mode, especially for a single cell source where the
low impedance discharge mode seems particularly possible for
deposition as well as the mentioned carbon reaction.
[0040] The transition or dividing line between modes of operation
may exist at a specific level, such as when the gas pressure in the
source exceeds some threshold level. (Note, however, that in order
to strike the discharge the applied may initially be high, but it
may eventually become low after ignition.) In the low impedance
discharge mode, the ion source can have a very high discharge
current and the "beam" can become a low impedance discharge mode
material processing ion flux. The ion source (2) acts as a low
impedance current source and as a current-independent-of-vo- ltage
source. As those of ordinary skill in the art would appreciate, the
gas pressure at which the transition occurs, which is appropriate,
or which creates a low impedance discharge mode material processing
ion flux gas environment can be a function of the gas feed rate and
the vacuum chamber pumping speed. It may be considerably or just
substantially higher than that in the deposition cycle. Whereas the
gas flow for the high impedance mode (as traditionally for
deposition) can be on the low side of the 1 to 1000 sccm range, the
low impedance flow (as may be particularly appropriate for the
reactive cycle, although both modes can work here, too, as well)
can be on the high side of that same range--especially for a multi
cell source. Naturally, the threshold gas pressure can also depend
on source design and magnetic field strength.
[0041] By example, the two different modes can be understood
through the various parameters of each cycle as follows. In each it
should be understood that the values are representative of values
as they might exist for only one type of system. As explained
throughout this disclosure, such values can vary based upon a
multitude of factors.
EXAMPLE 1
Multicell DLC Processing
[0042]
1 Deposition Cycle Reactive Cycle Source: AE MCIS Source: AE MCIS
Deposition Gas: 100% Butane Reaction Gas: 100% O.sub.2 Gas Flow: 5
sccm Gas Flow: 16 sccm Source Voltage: 1500 volts Source Voltage:
1000 volts Source Current: 0.25 amperes Source Current: 0.5
amperes
EXAMPLE 2
Single Cell DLC Processing
[0043]
2 Deposition Cycle Reactive Cycle Source: AE SCIS Source: AE SCIS
Deposition Gas: 100% Ethylene Reaction Gas: 100% O.sub.2 Gas Flow:
17 sccm Gas Flow: 10 sccm Source Voltage: 450 volts Source Voltage:
440 volts Source Current: 1 ampere Source Current: 2.5 amperes
[0044] As may be appreciated, an important difference is that in
the low impedance discharge mode, the reactive cycles shown above,
much higher discharge current and ion beam current can be delivered
onto a substrate, even though the ion energy is lower than in the
high impedance mode. Some processes benefit from high energy ions,
and some cannot tolerate them at all and can work only with the low
impedance discharge mode. In DLC system processing, the DLC
properties can depend on the ion energy, so both high and low
energy systems may be desirable.
[0045] As may be easily appreciated, the various times at which the
different cycles are accomplished can be configured in a variety of
ways. Certainly, the deposition and reaction cycles can be
accomplished alternatingly and even periodically. These can be
controlled by the timer element (11) determining a time to take an
action, equivalently by setting a period for an action, or
otherwise. Of course, the order may not be critical for many steps.
The deposition cycle from (plus disk removal) can be repeated
several times before the reaction and removal cycle occurs. The
efficiency of the process can also be evaluated as number of
deposition cycles for every reactive cycle, and this can establish
how many good disks one makes before one is missed. Significantly,
it has been discovered that with this disclosed process, the time
for reacting can be short compared to the time during which
deposition occurs. Again, some of the details are set forth in the
claims.
[0046] Further, by configuring the frequency of the reactive cycle
such that its period (whether determined by use of the action or
action plus purge time) is equivalent to a single substrate
processing time, more continuous feeding can occur. In this
fashion, a substrate can be discarded, or, more likely a dummy
substrate or no substrate at all may be "processed" in the reactive
cycle.
[0047] Thus there could be desired substrates and discardable
substrates, or even simply undesired ones or merely an avoidance of
feeding desired ones. Significantly the level of the reactive cycle
can be set to achieve maximum throughput or optimal throughput
(factoring in the quality of the results achieved) or even the
permit the maximum application of power. Once more, details are set
forth in the claims. Again, the control circuitry would thus serve
as a maximum power element and the timer element (11) could serve
as an optimal throughput timer element.
[0048] The aspect of maximum power may involve arc control. As
those skilled in the art understand, when processing it is
traditional to avoid arcs so as not to ruin the processing being
enacted. This can be facilitated by an arc avoidance element to
control the power application element (8) as is well known.
Interestingly, the deposition rate is often limited by arcing that
can start when discharge current exceeds a certain limit. Even one
arc during the deposition time may result in unacceptable particle
contamination of the disk. As to this aspect, the present invention
can even employ a ramped up power control as appropriate to
specific situations to permit maximal processing without arcing
since initial processing can be more prone to arc than later
processing of a substrate. Again some of the possible details are
mentioned in the claims. Further, applying the aspect of arc energy
(as discussed in U.S. Pat. No. 6,007,879 to the assignee of the
present invention, hereby incorporated by reference), can be
important during the reactive cycle when arcing is permitted. It
may be beneficial for some applications to hold the arc energy to
values below such energies as 5, 1, 10, 20, 50, or even perhaps 100
millijoules, with arc energy held at below 20 millijoules
potentially being of most benefit for removing carbon build ups in
a practical manner.
[0049] In addition, it its different mode of operation, the present
invention takes a different direction. It may actually include an
arc permission element (19)! This is shown schematically as
circuitry which actually controls the power application element (8)
in a manner which purposefully permits some arcing. While it is
possible that for some processing situations, the reactive cycle
speed could also be limited by arcing, in many it is not. Even
where it is, it can also be possible to run much higher discharge
currents and higher gas flow during reactive cleaning than during
the deposition process. As mentioned, some arcing may be acceptable
during the reactive cleaning cycle because there may be no
substrate effectively present. However, it is also possible that
too frequent arcs can reduce average discharge power due to dead
time by arc handling circuitry of the power supply. It, therefore,
can be desirable to make the reactive cycle time as short as
possible compared to the accumulated deposition time, so the
overall impact of the reactive cycle on the machine throughput
would be minimal. Accordingly, the present invention can use a
regulation loop in the power supply to keep the arc frequency below
a certain point using a feedback from an arc frequency monitoring
circuit to the power supply regulation loop.
[0050] As mentioned earlier, another embodiment is one which is
designed to achieve more a uniform deposition across the substrate
without a need to move the substrate. FIG. 7 shows a process vacuum
chamber (1) with two AE MCIS-12 ion sources (25) for installation
on an Intevac 250 machine. This apparatus can replace an existing
process chamber accommodating two magnetrons that deposit amorphous
carbon rather than DLC. The ion sources can be installed on spacers
(23) in order to optimize the distance to substrate. The chamber
may be somewhat wider than a standard chamber to allow for the
higher pumping speed which may be needed for a faster reactive
cleaning cycle. The reason for higher pumping requirements during
the reactive cleaning cycle may be that cleaning may require a
higher gas flow than the deposition cycle in order to accomplish
its objective in a shorter time than the cumulative deposition time
to keep throughput of the machine high. The machine may also be
programmed (26) to run a reactive cleaning cycle once after every
several disks, with a dummy disk, or with no disk at all in the
chamber at the time of cleaning. It is currently preferred that the
reactive cleaning cycle have the same duration as a deposition
cycle of one disk, so the machine works at a constant speed.
[0051] FIG. 1 depicts one way of implementing the radial gas flow
barriers (24) in an MCIS-12 ion source (25) manufactured by
Advanced Energy Industries, Inc. This embodiment can accommodate
the MCIS design. It is configured so that the gas flow between the
back cathode and the anode is from outer edge toward the center.
One or more cylindrical parts can be easily installed in this
region, as shown on FIG. 1. These may create a gas pressure drop
from the edge of the substrate. The heights of the barrier(s) can,
of course, be adjusted to compensate for the deposition rate roll
off at the edge and make the film thickness uniform from center to
edge of the substrate. The currently preferred material would be
stainless steel foil that can be spot welded to the back
cathode.
[0052] As can be understood, this embodiment of the present
invention can address at least two distinct modes of
non-uniformity. First, the ion beam from a multi-cell ion source,
such as the MCIS series manufactured by Advanced Energy Industries,
Inc., (AE) may often consist of many smaller beamlets that may
overlap at the substrate plane. This cell structure pattern can be
evident in the resulting deposited films. The pattern usually
weakens as the distance between the ion source and the substrate
increases as beamlets from individual cells overlap more. Thus
proper configuration can solve this type of nonuniformity.
[0053] A second source of non-uniformity can be due to limited ion
beam size. This may cause outer regions of the substrate to receive
less ions than the inner ones, so the deposition rate can tend to
roll off towards the edge. Here, the affected area can grow larger
as the distance between the ion source and the substrate increases.
Therefore, there can be a trade-off between cell pattern at short
distance and the roll-off at longer distance. The radial
non-uniformity can be augmented by the fact that even when each
cell of the ion source receives the same gas flow, the gas pressure
can tend to be higher at the center of the source. This pressure
non-uniformity can be bigger at higher pumping speeds because the
substrate presents an obstacle to the gas flow. The non-uniform gas
pressure can increase the deposition rate roll-off from the
substrate center outwards. Accordingly, some embodiments of the
present invention provide systems for source-substrate distance
optimization and the use of field-installable circular barriers
inside the ion source that can redistribute or constrict gas
pressure radially so that outer cells may receive more gas this
partially mitigating the above mentioned roll-off effect.
[0054] As mentioned earlier, this invention can be embodied in a
number of ways. In addition, each of the various elements of the
invention and claims may also be achieved in a variety of manners.
This disclosure should be understood to encompass each such
variation, be it a variation of am embodiment of any apparatus
embodiment, a method or process embodiment, or even merely a
variation of any element of these. Particularly, it should be
understood that as the disclosure relates to elements of the
invention, the words for each element may be expressed by
equivalent apparatus terms or method terms--even if only the
function or result is the same. Such equivalent, broader, or even
more generic terms should be considered to be encompassed in the
description of each element or action. Such terms can be
substituted where desired to make explicit the implicitly broad
coverage to which this invention in entitled. As but one example,
it should be understood that all action may be expressed as means
for taking that action or as an element which causes that action.
Similarly, each physical element disclosed should be understood to
encompass a disclosure of the action which that physical element
facilitates. Regarding this last aspect, the disclosure of a
"supply" should be understood to encompass disclosure of the act of
"supplying"--whether explicitly discussed or not--and, conversely,
were there are only disclosure of the act of "supplying", such
disclosure should be understood to encompass disclosure of a
"supply." Such changes and alternative terms are to be explicitly
included in the description.
[0055] The foregoing discussion and the claims which follow
describe the preferred embodiments of the invention. Particularly
with respect to the claims it should be understood that changes may
be made with departing from their essence. In this regard it is
intended that such changes would still fall within the scope of the
present invention. It is simply not practical to describe and claim
all possible revisions which may be accomplished to the present
invention. To the extent such revisions utilize the essence of the
invention each would naturally fall within the breadth of
protection accomplished by this patent. This particularly true for
the present invention since its basic concepts and understandings
are fundamental in nature and can be applied in a variety of ways
to a variety of fields.
[0056] Furthermore, any references mentioned in the application for
this patent as well as all references listed in any list of
references filed with the application are hereby incorporated by
reference in their entirety to the extent such may be deemed
essential to support the enablement or claiming of the
invention(s). However, to the extent statements might be considered
inconsistent with the patenting of this/these invention(s) such
statements are expressly not to be considered as made by the
applicant(s).
[0057] It should be understood that in the application the claims
may be expanded to address other aspects as well as those covered,
or to address the various combinations and permutations of all the
elements or applications are presented. Further, unless the context
requires otherwise, the word "comprise" or variations such as
"comprising" or "comprises", should be understood to imply the
inclusion of a stated element or step or group of elements or steps
but not the exclusion of any other element or step or group of
elements or steps.
* * * * *