U.S. patent application number 10/760713 was filed with the patent office on 2004-09-30 for methods for processing micro-feature workpieces, patterned structures on micro-feature workpieces, and integrated tools for processing micro-feature workpieces.
Invention is credited to Klocke, John, Ritzdorf, Thomas L..
Application Number | 20040188257 10/760713 |
Document ID | / |
Family ID | 26928144 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040188257 |
Kind Code |
A1 |
Klocke, John ; et
al. |
September 30, 2004 |
Methods for processing micro-feature workpieces, patterned
structures on micro-feature workpieces, and integrated tools for
processing micro-feature workpieces
Abstract
Method and apparatus for processing a micro-feature workpiece
having a workpiece having a first side, a second side, a plurality
of micro-devices including submicron features integrated in and/or
on the workpiece, and a deep depression or other large
three-dimensional feature in either the first side and/or the
second side. The method can include forming a thin conductive seed
layer on the workpiece that conforms to the depression, and
depositing a negative resist layer onto the seed layer. The
negative resist layer, for example, can be a highly conformal and
uniform layer of negative electrophoretic resist that is deposited
onto the seed layer by contacting the seed layer with a bath of
negative electrophoretic resist and establishing an electrical
field between the seed layer and an electrode in the bath. After
depositing the negative resist layer, the method includes removing
a portion of the negative resist layer to uncover a deposition area
of the seed layer within the depression. The method then includes
the additive technique of electrochemically depositing a material
onto the deposition area of the seed layer within the depression
without covering the entire workpiece with the material.
Inventors: |
Klocke, John; (Kalispell,
MT) ; Ritzdorf, Thomas L.; (Bigfork, MT) |
Correspondence
Address: |
PERKINS COIE LLP
PATENT-SEA
P.O. BOX 1247
SEATTLE
WA
98111-1247
US
|
Family ID: |
26928144 |
Appl. No.: |
10/760713 |
Filed: |
January 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10760713 |
Jan 20, 2004 |
|
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10234637 |
Sep 3, 2002 |
|
|
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60316461 |
Aug 31, 2001 |
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Current U.S.
Class: |
204/478 ;
205/188; 205/205 |
Current CPC
Class: |
H01L 21/2885 20130101;
H01L 21/76898 20130101; C25D 13/00 20130101; C25D 7/123 20130101;
H01L 21/6723 20130101; C25D 5/022 20130101; H01L 21/6719 20130101;
C25D 13/12 20130101 |
Class at
Publication: |
204/478 ;
205/188; 205/205 |
International
Class: |
C25D 013/00 |
Claims
We claim:
1. A method for processing a micro-feature workpiece having a first
side, a second side, a plurality of micro-devices integrated in
and/or on the workpiece, and at least one deep depression in the
first side and/or the second side, the method comprising: forming a
conductive seed layer that extends into the deep depression in the
workpiece; depositing a conformal, uniformly thick negative resist
layer onto the seed layer; exposing portions of the negative resist
layer outside of the depression to a selected energy to form an
exposed region of the negative resist layer outside of the
depression and an unexposed region of the negative resist layer in
the depression; removing the unexposed region of the negative
resist layer to uncover a deposition area of the seed layer in the
depression; and electrochemically depositing a conductive material
onto the deposition area of the seed layer.
2. The method of claim 1 wherein depositing the negative resist
layer comprises electrochemically depositing a conformal layer of
negative electrophoretic resist onto the seed layer.
3. The method of claim 1 wherein depositing the negative resist
layer comprises electrochemically depositing a conformal layer of
negative electrophoretic resist onto the seed layer by: contacting
the seed layer with a bath of negative electrophoretic resist; and
establishing an electrical field between the seed layer and an
electrode in the bath of negative electrophoretic resist.
4. The method of claim 1 wherein depositing the negative resist
layer comprises electrochemically depositing a conformal layer of
negative electrophoretic resist onto the seed layer by: holding the
workpiece at least substantially horizontal and contacting the seed
layer with a bath of negative electrophoretic resist while
isolating another region of the workpiece from contacting the bath;
and establishing an electrical field between the seed layer and an
electrode in the bath of negative electrophoretic resist.
5. The method of claim 1 wherein depositing the negative resist
layer comprises electrochemically depositing a conformal layer of
negative electrophoretic resist onto the seed layer by: holding the
workpiece at least substantially horizontal and contacting the seed
layer with a bath of negative electrophoretic resist while
isolating another region of the workpiece from contacting the bath;
rotating the workpiece while the seed layer contacts the bath; and
establishing an electrical field between the seed layer and an
electrode in the bath of negative electrophoretic resist.
6. The method of claim 1 wherein exposing the workpiece comprises
aligning a mask with the depression to block the energy from
irradiating the negative resist in the depression.
7. The method of claim 1 wherein electrochemically depositing a
conductive material comprises electroplating a metal onto the
deposition area of the seed layer by contacting the workpiece with
a bath of electroplating solution and establishing an electrical
field between the deposition area of the seed layer and an
electrode in the bath of the electroplating solution.
8. The method of claim 1 wherein electrochemically depositing a
conductive material comprises electroplating gold onto the
deposition area of the seed layer by contacting the workpiece with
a bath of electroplating solution containing gold ions and
establishing an electrical field between the deposition area of the
seed layer and an electrode in the bath of the electroplating
solution.
9. The method of claim 1 wherein: the workpiece comprises a
microelectronic workpiece having a semiconductor substrate and a
plurality of semiconductor devices integrally formed in discrete
dies on the substrate; and depositing a negative resist layer
comprises contacting the seed layer with a bath of negative
electrophoretic resist in an electrochemical resist deposition
station, establishing an electrical field between the seed layer
and an electrode in the bath of negative electrophoretic resist,
and rinsing in-situ within the electrochemical resist deposition
station.
10. The method of claim 1 wherein: the workpiece comprises a
microelectronic workpiece having a semiconductor substrate and a
plurality of semiconductor devices integrally formed in discrete
dies on the substrate; depositing a negative resist layer comprises
contacting the seed layer with a bath of negative electrophoretic
resist and establishing an electrical field between the seed layer
and an electrode in the bath of negative electrophoretic resist;
and electrochemically depositing a conductive material comprises
electroplating gold or copper onto the deposition area of the seed
layer by contacting the workpiece with a bath of electroplating
solution containing gold ions and establishing an electrical field
between the deposition area of the seed layer and an electrode in
the bath of electroplating solution.
11. The method of claim 1 wherein: the workpiece comprises a
microelectronic workpiece having a semiconductor substrate and a
plurality of semiconductor devices integrally formed in discrete
dies on the substrate; the deep depression comprises a backside via
extending through the substrate from the first surface to the
second surface; depositing a negative resist layer comprises
contacting the seed layer with a bath of negative electrophoretic
resist and establishing an electrical field between the seed layer
and an electrode in the bath of negative electrophoretic resist to
cover the backside via with a conformal layer of the negative
electrophoretic resist; and electrochemically depositing a
conductive material comprises electroplating gold or copper onto
the deposition area of the seed layer by contacting the workpiece
with a bath of electroplating solution containing gold ions and
establishing an electrical field between the deposition area of the
seed layer and an electrode in the bath of electroplating
solution.
12. A method for processing a micro-feature workpiece, comprising:
providing a workpiece having a first side, a second side, a
plurality of micro-devices formed integrally on and/or in the
workpiece, and at least one deep depression in the first side
and/or the second side; forming a thin conductive seed layer that
extends into a deep depression in the workpiece; constructing a
conformal layer of negative resist on the seed layer by
electrochemically depositing the negative resist onto the seed
layer; irradiating portions of the conformal layer of negative
resist in areas outside of the depression to form an exposed
pattern of negative resist outside of the depression and an
unexposed pattern of negative resist in the depression; removing
the unexposed pattern of negative resist to uncover a deposition
area of the seed layer in the depression; and electrochemically
depositing a conductive material onto the deposition area of the
seed layer.
13. The method of claim 12 wherein constructing the conformal layer
of negative resist comprises electrochemically depositing negative
electrophoretic resist onto the seed layer in a single-wafer
processing chamber while rotating the workpiece.
14. The method of claim 12 wherein constructing the conformal layer
of negative resist comprises electrochemically depositing negative
electrophoretic resist onto the seed layer by: contacting the seed
layer with a bath of negative electrophoretic resist; and
establishing an electrical field between the seed layer and an
electrode in the bath of negative electrophoretic resist.
15. The method of claim 12 wherein constructing the conformal layer
of negative resist comprises electrochemically depositing negative
electrophoretic resist onto the seed layer by: holding the
workpiece at least substantially horizontal and contacting the seed
layer with a bath of negative electrophoretic resist while
isolating another region of the workpiece from contacting the bath;
and establishing an electrical field between the seed layer and an
electrode in the bath of negative electrophoretic resist.
16. The method of claim 12 wherein constructing the conformal layer
of negative resist comprises electrochemically depositing negative
electrophoretic resist onto the seed layer by: holding the
workpiece at least substantially horizontal and contacting the seed
layer with a bath of negative electrophoretic resist while
isolating another region of the workpiece from contacting the bath;
rotating the workpiece while the seed layer contacts the bath; and
establishing an electrical field between the seed layer and an
electrode in the bath of negative electrophoretic resist.
17. The method of claim 12 wherein irradiating portions of the
workpiece comprises aligning a mask with the depression to block
the energy from irradiating the negative resist in the
depression.
18. The method of claim 12 wherein electrochemically depositing the
conductive material comprises electroplating a metal onto the
deposition area of the seed layer by contacting the workpiece with
a bath of electroplating solution and establishing an electrical
field between the deposition area of the seed layer and an
electrode in the bath of the electroplating solution.
19. The method of claim 12 wherein electrochemically depositing the
conductive material comprises electroplating gold onto the
deposition area of the seed layer by contacting the workpiece with
a bath of electroplating solution containing gold ions and
establishing an electrical field between the deposition area of the
seed layer and an electrode in the bath of the electroplating
solution.
20. The method of claim 12 wherein: the workpiece comprises a
microelectronic workpiece having a semiconductor substrate and a
plurality of semiconductor devices integrally formed in discrete
dies on the substrate; and constructing the conformal layer of
negative resist comprises contacting the seed layer with a bath of
negative electrophoretic resist and establishing an electrical
field between the seed layer and an electrode in the bath of
negative electrophoretic resist.
21. The method of claim 12 wherein: the workpiece comprises a
microelectronic workpiece having a semiconductor substrate and a
plurality of semiconductor devices integrally formed in discrete
dies on the substrate; constructing the conformal layer of negative
resist comprises contacting the seed layer with a bath of negative
electrophoretic resist and establishing an electrical field between
the seed layer and an electrode in the bath of negative
electrophoretic resist; and electrochemically depositing the
conductive material comprises electroplating gold onto the
deposition area of the seed layer by contacting the workpiece with
a bath of electroplating solution containing gold ions and
establishing an electrical field between the deposition area of the
seed layer and an electrode in the bath of electroplating
solution.
22. The method of claim 12 wherein: the workpiece comprises a
microelectronic workpiece having a semiconductor substrate and a
plurality of semiconductor devices integrally formed in discrete
dies on the substrate; the deep depression comprises a backside via
extending through the substrate from the first surface to the
second surface; constructing the conformal layer of negative resist
comprises contacting the seed layer with a bath of negative
electrophoretic resist and establishing an electrical field between
the seed layer and an electrode in the bath of negative
electrophoretic resist to form the conformal layer of the negative
electrophoretic resist in the backside via; and electrochemically
depositing the conductive material comprises electroplating gold
onto the deposition area of the seed layer by contacting the
workpiece with a bath of electroplating solution containing gold
ions and establishing an electrical field between the deposition
area of the seed layer and an electrode in the bath of
electroplating solution.
23. A micro-feature workpiece, comprising: a substrate; a plurality
of micro-devices formed integrally with the substrate; a deep
depression having a sidewall extending into the substrate; a
conductive seed layer on the substrate and the sidewall of the deep
depression; and a conformal layer of negative electrophoretic
resist on the seed layer.
24. The micro-device workpiece of claim 23 wherein the conformal
layer of resist has an irradiated portion outside of the depression
and a non-irradiated portion in the depression, and wherein the
non-irradiated portion has a higher. solubility in a developing
solution than the irradiated portion.
25. The micro-device workpiece of claim 23 wherein: the substrate
comprises a semiconductor wafer; and the micro-devices comprise
semiconductor dies formed integrally with the wafer, and the dies
include integrated circuitry having submicron features.
26. The micro-device workpiece of claim 23 wherein: the substrate
comprises a semiconductor wafer; and the micro-devices comprise
semiconductor dies formed integrally with the wafer, and the dies
include supramicron features.
27. The micro-device workpiece of claim 23 wherein: the substrate
comprises a micromechanical wafer; and the micro-devices comprise
micromechanical devices formed integrally with the wafer, and the
micromechanical devices have submicron features.
28. The micro-device workpiece of claim 23 wherein: the substrate
comprises a micromechanical wafer; and the micro-devices comprise
micromechanical devices formed integrally with the wafer, and the
micromechanical devices have supramicron features.
29. The micro-device workpiece of claim 23 wherein: the substrate
comprises a semiconductor wafer; the micro-devices comprise
semiconductor dies formed integrally with the wafer, and the dies
include integrated circuitry having submicron features; the deep
depression comprises at least one backside via having a sidewall
extending completely through the wafer; and the conformal layer of
electrophoretic negative resist has a thickness that is at least
substantially constant along the sidewall of the backside via.
30. The micro-device workpiece of claim 23 wherein: the substrate
comprises a semiconductor wafer; the micro-devices comprise
semiconductor dies formed integrally with the wafer, and the dies
include integrated circuitry having submicron features; the deep
depression comprises a backside via having a sidewall extending
completely through the wafer; the conformal layer of negative
resist has an irradiated portion outside of the backside via and an
opening over the seed layer in the backside via defining a
deposition area; and a metal is deposited in the deposition area
but not on the resist.
31. An integrated tool for processing a micro-feature workpiece,
comprising: a cabinet; an electrophoretic emulsion (EPE) deposition
station in the cabinet, the EPE deposition station having a reactor
including a cup configured to contain an EPE and a workpiece holder
configured to isolate at least one region of the workpiece from EPE
in the cup; a first wet processing station in the cabinet, the
first wet processing station comprising a chamber configured to
develop electrophoretic resist; a second wet processing station in
the cabinet, the second wet processing station being an
electrochemical deposition station configured to deposit conductive
material onto the workpiece; and a workpiece handling apparatus in
at least a portion of the cabinet, the workpiece handling apparatus
being configured to contact the region of the workpiece isolated
from the EPE to transport the workpiece relative to the EPE
station, the chamber, and the electrochemical deposition station.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/234,637, entitled "APPARATUS and METHOD for
DEPOSITION of an ELECTROPHORETIC EMULSION," filed on Sep. 3, 2002,
which claims priority to U.S. Patent Application No. 60/316,461,
filed on Aug. 31, 2001, both of which are incorporated by reference
herein.
TECHNICAL FIELD
[0002] The present invention is directed to methods for processing
micro-feature workpieces having a plurality of micro-devices that
are integrated in and/or on the workpiece. The micro-devices can
include submicron features. Additional aspects of the present
invention include micro-feature workpieces that have patterned
structures, and integrated tools that carry out methods in
accordance with the invention for manufacturing micro-feature
workpieces.
BACKGROUND
[0003] In the fabrication of microelectronic devices and
micromechanical devices, several layers of materials are typically
deposited and worked on a single substrate to produce a large
number of individual devices. For example, layers of photoresist
(resist) are deposited and worked (i.e., patterned, developed,
etched, and so forth) to form patterns of features in and/or on the
substrate. The patterns are then used to form various
structures.
[0004] The microelectronics industry continually seeks to reduce
manufacturing costs and improve the performance of the
microelectronic devices. The manufacturing costs can be reduced, in
part, by reducing the volume of materials that are consumed in
fabricating the individual components. For example, a manufacturer
can achieve significant savings by reducing the amount of gold,
resist, or other materials that are used in typical fabrication
processes. Additionally, manufacturers seek to increase the density
of features so that more components and devices can be fabricated
on a single wafer. Therefore, microelectronic manufacturers
continually seek more efficient processes that reduce the
manufacturing costs and improve the performance of their
products.
[0005] One aspect of manufacturing microelectronic devices that can
be problematic is forming conductive features in through-holes, in
deep depressions, or on other three-dimensional structures. Several
products, such as telecommunications products, have backside vias
that extend completely through the workpiece or other deep
depressions that have large step heights. Such three-dimensional
structures cause several problems in manufacturing processes
including step coverage and inefficient use of materials. Referring
to FIGS. 1A-1E, for example, a backside via is currently formed
using a subtractive process including the following steps:
[0006] (A) Forming a through-hole 130 completely through a
substrate 110 of a workpiece 100 (FIG. 1A).
[0007] (B) Depositing a seed layer 140 on the substrate 110 and
into the through hole 130 (FIG. 1A).
[0008] (C) Plating the entire substrate 110 with a layer of gold
150 or other material (FIG. 1A).
[0009] (D) Depositing a layer of resist 160 over the substrate 110
using a spin-on or dry film technique (FIG. 1B).
[0010] (E) Patterning the resist 160 to leave masked regions 162
over the through holes 130 and to expose the gold layer 150 outside
of the through holes 130 (FIG. 1C).
[0011] (F) Etching the exposed portions of the gold layer 150 and
the seed layer 140 outside of the through holes 130 (FIG. 1D).
[0012] (G) Removing the masks 162 to expose gold contacts 170
within the through holes 130 (FIG. 1E).
[0013] The subtractive process shown in FIGS. 1A-1E is inefficient
and difficult to perform. One problem with this subtractive process
is that it is difficult and expensive to deposit and work the layer
of resist. For example, spin-on techniques do not provide good step
coverage in deep depressions or over other features with large step
heights because the resist may not cover the upper regions on the
sidewalls (see FIGS. 1B-1D). This can cause defects in subsequent
manufacturing. To provide adequate step coverage using spin-on
techniques, a significant amount of resist is deposited such that
the through holes are substantially filled with resist but the top
surface is covered by only a thin layer. Depositing such a
non-uniform layer of resist, however, is relatively expensive
because (a) a significant amount of resist is wasted as it flows
off the wafer, and (b) the non-uniform layer of resist requires
longer exposure periods and stripping cycles that take more time
and use more consumable materials. Therefore, conventional
subtractive processes that use spin-on techniques for depositing
the layer of resist are expensive and make it more difficult to
provide consistent exposure and stripping processes.
[0014] Another problem of conventional subtractive processes for
forming conductive features in backside vias or other deep
depressions is that a significant amount of gold or other
relatively expensive conductive material is wasted. Conventional
subtractive processes use a positive photoresist and expose the
areas outside of the deep depressions. The positive photoresist is
exposed in the areas outside of the deep depressions because (a) it
is difficult to adequately focus the exposure radiation in the deep
depressions, and (b) the layer of photoresist is much more uniform
on top of the substrate than within the depressions. As a result,
the portion of the gold or other conductive material outside of the
vias is removed from the workpiece to form the conductive
features.
[0015] A significant portion of the gold is thus wasted in the
etching process because only a fraction of it remains on the wafer.
Therefore, a significant amount of the precious metals or other
conductive materials that are used to form contacts in deep
depressions are wasted in conventional subtractive processes.
SUMMARY
[0016] The present invention is directed toward forming several
types of features on or in micro-feature workpieces, and unique
processes for depositing a uniformly conformal layer of negative
resist over large step heights. Several embodiments of the
invention enable additive processes for forming features that
reduce costs, increase throughout, and enhance reliability.
[0017] One aspect of the present invention is forming a conformal,
uniform layer of negative resist on a workpiece with large
three-dimensional structures (i.e., large step heights) and then
removing the portion of the negative resist within the large
three-dimensional structures. A conductive feature or other
features can then be formed by adding material to the wafer within
the three-dimensional structures instead of over the entire wafer
so that extensive etching is not necessary to remove excess
material from the wafer. This reduces the consumption of precious
metals or other materials. Additionally, forming a conformal,
uniform layer of resist reduces the quantity of resist required to
adequately cover large three-dimensional features. This provides
more consistent exposure, development, and stripping processes to
reduce defects, and results in faster process times to enhance the
throughput and cost-effectiveness for manufacturing the
features.
[0018] One embodiment of a method for processing a micro-feature
workpiece involves a workpiece having a first side, a second side,
a plurality of micro-devices including submicron features
integrated in and/or on the workpiece, and a deep depression or
other large three-dimensional feature in either the first side
and/or the second side. The method can include forming a thin
conductive seed layer on the workpiece that conforms to the
depression, and depositing a negative resist layer onto the seed
layer. The negative resist layer, for example, can be a highly
conformal and uniform layer of negative electrophoretic resist. The
negative resist layer can be deposited onto the seed layer by
contacting the seed layer with a bath of negative electrophoretic
resist and establishing an electrical field between the seed layer
and an electrode in the bath. After depositing the negative resist
layer, the method includes exposing portions of the negative resist
layer outside of the depression to a selected energy. This creates
an exposed region of the negative resist layer outside of the
depression and an unexposed region of the negative resist layer in
the depression. The unexposed region of the negative resist layer
in the depression is removed to uncover a deposition area of the
seed layer within the depression. The method then includes the
additive technique of electrochemically depositing a material onto
the deposition area of the seed layer within the depression without
covering the entire workpiece with the material. The exposed
regions of. the negative resist layer outside of the depression can
then be removed to expose the portions of the seed layer outside of
the depression, and then the seed layer can be quickly etched to
isolate the electrochemically deposited material in the
depression.
[0019] The methods for processing a micro-feature workpiece in
accordance with the invention define an additive process in which a
precious metal or other material is not wasted because it is
deposited only in the area of the feature instead of across the
entire surface of the workpiece. Moreover, electrochemically
depositing a layer of negative electrophoretic resist enables this
additive process because it provides conformal, uniform coverage
over large three-dimensional features. This reduces the amount of
resist that is used compared to spin-on techniques because the
thickness of the resist layer can be tightly controlled using
electrochemical deposition of electrophoretic resist. The conformal
layer of resist also reduces defects because it can be patterned
using consistent exposure, development, and stripping processes.
Therefore, several aspects of embodiments for processing a
micro-feature workpiece in accordance with the invention reduce the
cost of materials, reduce the defects, and enhance the throughput
for forming features in and/or on large three-dimensional
structures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIGS. 1A-1E are cross-sectional views illustrating a portion
of a micro-feature workpiece at various stages of a subtractive
method for forming a conductive feature in a deep depression in
accordance with the prior art.
[0021] FIGS. 2A-2F are cross-sectional views of a micro-feature
workpiece at various stages of an additive method for forming
features in deep depressions in accordance with an embodiment of
the invention.
[0022] FIG. 3 is an isometric view of one embodiment of an
automated processing tool for processing a micro-feature workpiece
in accordance with the invention.
[0023] FIG. 4 is a cross-sectional view of one embodiment of a
processing reactor that may be used in an automated processing tool
to deposit a conformal layer of negative electrophoretic resist
onto a seed layer in accordance with an embodiment of the
invention.
[0024] FIG. 5 is a flow diagram of a control sequence for
processing a micro-feature workpiece in accordance with an
embodiment of the invention.
[0025] FIGS. 6-8 are top plan schematic views illustrating
additional embodiments of integrated tools in accordance with other
embodiments of the invention.
DETAILED DESCRIPTION
[0026] As used herein, the terms "micro-feature workpiece" or
"workpiece" refer to substrates on or in which microelectronic
devices are integrally formed, such as microelectronic circuits or
components, thin-film recording heads, data storage elements, and
similar devices. Micromachines or micromechanical devices are
included within this definition because the manufacturing processes
used to make them are the same as or similar to the manufacturing
processes used in the fabrication of integrated circuits. The
substrates can be semiconductive pieces (e.g., silicon wafers),
nonconductive pieces (e.g., various ceramic substrates), or
conductive pieces. Typical workpieces are relatively thin and
disk-shaped, although not necessarily circular, as ordinarily
understood in the microfabrication industry. The work-pieces can
also be mounted to carrier substrates that are typically relatively
thin and disk shaped, although not necessarily circular.
[0027] Several embodiments of micro-feature workpieces and methods
for processing micro-feature workpieces are described in the
context of forming backside vias or other structures in deep
depressions on a workpiece. The present invention, however, is not
limited to forming such structures. The present invention is
applicable to forming structures with a conformal layer of
photoresist over any large three-dimensional structure on a
workpiece. For example, other structures can include raised
features or depressions such as streets, backside patterns, and
other features used in MEMS, communications devices, optics and
advanced packaging applications.
[0028] Additionally, several embodiments are described in the
context of electrochemically depositing an electrophoretic
photoresist (EPR) onto a workpiece. Yet, the present invention is
not limited to electrophoretic deposition of EPR. It may be
possible to deposit the resist using other methods, such as spin-on
deposition or spray coating in some embodiments, or perhaps
electrochemical processes can be used to deposit suitable
electrophoretic emulsions (EPEs) other than EPR emulsions. For
example, other materials that can be contained in an emulsion and
deposited by electrophoresis include phosphor materials for use in
high resolution flat panel display devices and various selectively
depositable dielectric materials.
[0029] A. Forming Micro-Features in or on Large Three-Dimensional
Structures
[0030] FIGS. 2A-2F illustrate a micro-feature workpiece 200 at
various stages of a method in accordance with one embodiment of the
invention. The method disclosed in FIGS. 2A-2F, more specifically,
is directed toward manufacturing backside vias or other features in
deep depressions. As explained above, however, the invention is not
limited to such structures and can be applied in the formation of
other features on and/or in large three-dimensional structures.
[0031] Referring to FIG. 2A, the workpiece 200 includes a substrate
210 and a plurality of micro-devices 220 that are integrally formed
on and/or in the substrate 210. The substrate 210, for example, can
be a semiconductor substrate, a nonconductive substrate, or any
other type of substrate that is suitable for manufacturing
microelectronic devices, micromechanical devices, or other types of
micro-devices 220. In many applications, the micro-devices 220 are
formed integrally on and/or in the substrate 210, and the
micro-devices 220 can have features as small as approximately 0.05
microns to 10 microns. The substrate 210 can include a plurality of
deep depressions, such as through holes 230 or trenches 240. The
substrate 210 can also include other types of large
three-dimensional structures such as ridges or studs that have step
heights from approximately 10-500 microns.
[0032] In the embodiment shown in FIG. 2A, the workpiece 200
further includes a seed layer 250 deposited on the substrate 210
and a negative resist layer 260 deposited on the seed layer 250.
The material of the seed layer 250 is selected according to the
type of material that is to be electrochemically deposited onto the
workpiece 200. For example, the seed layer 250 can be copper, gold,
or other suitable materials. The seed layer 250 can be deposited
using chemical -vapor deposition, physical vapor deposition, atomic
layer deposition, electroless plating, or other suitable methods.
The negative resist layer 260 can be deposited using an
electrochemical deposition process in which the substrate 210
contacts a bath of negative electrophoretic resist while an
electrical field is present between the seed layer 250 and another
electrode in the bath. Suitable processes for electrochemically
depositing the negative resist layer 260 are described in more
detail below with reference to FIGS. 3-8.
[0033] FIG. 2B illustrates the workpiece 200 at another stage of
the method in which portions of the negative resist layer have been
exposed to a selected energy "R" or otherwise irradiated to form a
patterned resist layer. In one embodiment, the portions of the
negative resist layer 260 on the top surface of the substrate 210
outside of the depressions 230/240 are exposed to the selected
energy, while the portions of the negative resist in the
depressions 230/240 are not exposed to the energy. The negative
resist layer 260 accordingly has exposed regions 262 outside of the
depressions 230/240 and unexposed regions 264 in the depressions
230/240. By exposing only the highly uniform, conformal areas of
the negative resist layer 260 on top of the substrate 210 instead
of the areas in the depressions 230/240, it is possible to use
consistent focusing and exposure times. It will be appreciated that
this is particularly beneficial because it becomes more difficult
to focus the selected energy accurately throughout the depths of
the deep depressions 230/240, or requires less "depth of field from
the exposure system.
[0034] FIG. 2C illustrates the workpiece 200 at a subsequent stage
of the method in which the unexposed regions 264 of the negative
resist layer 260 have been removed. The exposed regions 262 of the
negative resist layer 260 become less soluble in a selected
developing solution such that the unexposed regions 264 of the
negative resist layer 260 can be preferentially removed relative to
the exposed regions 262. Removing the unexposed regions 264 of the
negative resist layer 260 uncovers deposition areas 252 on the seed
layer 250 in the depressions 230/240. The deposition areas 252 are
surfaces upon which a conductive material can be plated using an
electrochemical deposition process.
[0035] FIG. 2D illustrates the micro-feature workpiece 200 at a
subsequent stage in the method after individual features 270 have
been electrochemically deposited onto the deposition areas 252. In
one embodiment, the features 270 can be conductive vias formed from
copper, gold, or other suitable materials that are
electrochemically deposited onto the deposition areas 252 by either
electroless plating techniques or electroplating techniques. For
example, an electroplating procedure for depositing gold onto the
deposition areas 252 includes contacting the deposition areas 252
with a plating solution while establishing an electrical field
between another electrode in the plating solution and the
deposition areas 252. Suitable processing stations and workpiece
holders for electrochemical deposition processes are described in
U.S. application Ser. Nos. 09/804,696; 09/804,697; 09/872,151;
09/875,365; 09/386,558; and 10/234,442, all of which are herein
incorporated by reference.
[0036] FIGS. 2E and 2F illustrate the workpiece 200 in the final
stages for forming micro-features on the workpiece 200. Referring
to FIG. 2E, the exposed regions 262 of the negative resist have
been removed from the workpiece 200 to expose portions of the seed
layer 250 on the top surface of the substrate 210. As shown in FIG.
2F, the exposed portions of the seed layer 250 on top of the
substrate 210 have been removed using a suitable etching procedure.
The process shown in FIGS. 2A-2F accordingly forms discrete
contacts in and/or on large three-dimensional structures such as
through holes 230 or deep trenches 240 in a manner that provides
several advantages compared to the conventional subtractive process
described above with respect to FIGS. 1A-1E.
[0037] One advantage of several embodiments of methods in
accordance with the invention is that they are less susceptible to
defects than the subtractive process shown above in FIG. 1A-1E. The
highly uniform, conformal layer of negative electrophoretic resist
260 is less susceptible to having defects than a resist layer
formed using spin-on or other techniques. For example, the upper
regions of the sidewalls are less likely to be exposed in
applications that use a conformal electrophoretic resist deposited
using electrochemical techniques compared to the nonconformal
layers that are deposited using spin-on techniques. Therefore, one
advantage of embodiments of methods in accordance with FIGS. 2A-2F
is that they are expected to provide better quality devices.
[0038] Another advantage of several embodiments of the methods
shown in FIGS. 2A-2F is that they efficiently use the resist,
electrochemically deposited conductive material, and other
consumable materials. The additive processes shown above in FIGS.
2A-2F only use enough gold to deposit a thin seed layer and fill
the depressions where the gold will remain on the workpiece, but
the subtractive process shown in FIGS. 1A-1E covers the entire
workpiece with a relatively thick layer of gold and then etches the
unwanted portions of the gold layer. The additive processes shown
in FIGS. 2A-2F accordingly use significantly less gold than the
subtractive process shown in FIGS. 1A-1E. Moreover, because the
negative electrophoretic resist layer 260 is formed using
electrochemical deposition, the processes shown in FIGS. 2A-2F also
use less resist than the subtractive processes. The conformal layer
of resist 260 also requires less developing fluid and washing fluid
because it has a uniform thickness in the depressions 230-240.
Therefore, several embodiments of methods described above with
reference to FIGS. 2A-2F efficiently use the materials in a manner
that reduces the material cost of forming features.
[0039] Several embodiments of methods in accordance with the
invention also enhance the throughput of processing workpieces. For
example, consistent and efficient processes for exposing,
developing, and washing the resist layer 260 can be developed
because it is a highly conformal, uniform layer. This allows
manufacturers to optimize the processes for working the negative
resist layer so that they can shorten the cycle times for these
processes. Therefore, several embodiments of methods in accordance
with the invention are expected to enhance the throughput of
manufacturing micro-features on workpieces.
[0040] B. Automated Micro-Feature Processing Tools
[0041] The additive methods for forming features described in FIGS.
2A-2F can be executed in one or more automated processing tools.
The following description of automated processing tools provides
several examples of methods and systems for forming the conformal
layer of resist and other layers on the workpiece. The automated
processing tools can be integrated with additional microfabrication
processing tools to form a complete microfabrication processing
system. For example, it is well within the scope of the present
invention to have different configurations of automated processing
tools that include several different types of processing stations,
such as an automated EPE station, an exposure station, a chemical
etching station, and/or a metal depositing station.
[0042] As explained in more detail below, the microelectronic
workpieces can be transferred between processing stations manually
or by automatic robotic handling equipment.
[0043] FIG. 3 is an isometric view of an automated microelectronic
processing tool 310 having an EPE deposition station 311 for
depositing EPR or other electrophoretic materials. The processing
tool 310 may include a cabinet 312 having an interior region 313
that is at least partially isolated from an exterior region 314
(e.g., a clean room). The cabinet 312 may be an enclosed structure
including a plurality of apertures 315 (only one shown in FIG. 3)
through which microelectronic workpieces 316 contained in cassettes
317 can move to or from load/unload station 318. In other
embodiments, the cabinet can be open, such as the layouts and tool
platforms shown in U.S. application Ser. Nos. 10/080,914 and
10/080,915, which are herein incorporated by reference.
[0044] The embodiments of the tool 310 shown in FIG. 3 include one
or more EPE deposition stations 311, one or more fluid processing
stations 324, a workpiece handling system 326, and a photoresist
baking station 325. The EPE deposition stations 311 may also
include an in-situ rinse assembly or other ancillary in-situ
process. For example, after a deposition cycle, the in-situ rinse
may be used to rinse the workpiece at the EPE station 311 before it
is transferred to another station. In this way, cross-contamination
with other reactors is reduced and the footprint of the processing
tool is more efficient. Further, the in-situ rinse may be used to
clean the electrodes and/or any seals that contact the workpiece
during deposition to remove any buildup of material on the
electrodes and/or seals. This in-situ cleaning process may involve
cleaning only the electrodes without having a workpiece loaded in
the EPE station 311.
[0045] The fluid processing stations 324 may execute one or more
different process sequences, such as pre-cleaning and/or
pre-wetting the workpiece before EPR deposition, cleaning the
workpiece after EPR deposition, baking the EPR coating, developing
the EPR coating following exposure, depositing metallization on the
workpiece, enhancing the seed layer prior to either EPR deposition
or metallization deposition, and several other processes.
[0046] The particular embodiment of the processing tool shown in
FIG. 3 is a "linear" tool in which the processing stations are
aligned in a generally linear fashion on one or both sides of the
workpiece handling system 326. In this type of system, the
workpiece handling system 326 includes a linear track 328 and one
or more robotic transfer mechanisms 330 that travel along the
linear track 328. In the particular embodiment shown in FIG. 3, a
first set of processing stations is arranged in a generally linear
manner along a first row R.sub.1-R.sub.1 and a second set of
processing stations is arranged in a generally linear manner along
a second row R.sub.2-R.sub.2. The linear track 328 extends between
the first and second rows of the processing stations so that the
robot unit 330 can access one or more of the processing stations
along the track 328 to load and/or unload workpieces.
[0047] The workpiece handling system 326, as well as the actuatable
components of the processing stations 311 and 324, are in
communication with a control unit 346. The control unit 346 can
implement software programming or other computer operable
instructions in response to user input parameters. The control unit
346 may include at least one graphical user interface 348
including, for example, a user-friendly display through which input
parameters are entered into the control unit 346. Optionally, the
user interface may be located on an area of the tool or at a remote
location. In the case of the latter implementation, the control
unit 346 may also include a communicating link for communicating
with the remote user interface. It will be recognized that a number
of control units 346 may be connected to a common control system
(not illustrated) that is used to control and oversee the
operations performed in the microfabrication facility or sections
thereof. Among its many functions, the control unit 346 is
programmed to control the transfer of microelectronic workpieces
between the various processing stations and between the
input/output section and the processing stations. Further, the
control unit 346 is programmed to control the operation of the
components at the individual processing stations to implement
specific processing sequences in response to the user input
parameters.
[0048] C. Embodiments of EPE Deposition Reactors
[0049] EPE deposition reactors electrochemically deposit EPRs or
other EPEs onto microelectronic workpieces. As used herein, the
term "electrochemically" includes (a) electrical processes that
establish an electrical field in a bath using the workpiece as an
anode or a cathode and (b) electroless processes that rely on the
electrochemical interaction between the workpiece and the bath
without inducing an electrical field in the bath. In general, the
EPE deposition reactors are particularly suitable for depositing
the conformal, uniform layer of negative resist 260 over and/or in
large three-dimensional structures as described above with
reference to FIG. 2B. Several embodiments of reactors for use in
processing tools are single-wafer units that hold a workpiece at
least substantially horizontal so that the EPE bath contacts only
one side of the workpiece. This allows the other side of the
workpiece to remain "clean" or otherwise isolated so that
single-wafer handling equipment is not fouled by the EPE. Several
embodiments of reactors also control bubbles to mitigate pinholes.
In some embodiments, deposition of photoresist is prevented at the
edge of the wafer so that an edge bead removal process is not
needed.
[0050] FIG. 4 illustrates one embodiment of a reactor assembly 400
that can be used for the EPE deposition station 311 of the
processing tool 310 (FIG. 3). In one embodiment, the reactor
assembly 400 comprises a reactor head 405 and a reactor base 410.
The reactor head 405 includes a stator 407, a rotor 420 carried by
the stator 407, and a workpiece holder 425 carried by the rotor
420. The reactor base 410 includes a processing area or vessel
suitable for EPR deposition or deposition from other EPEs. The
general design of the reactor depicted in FIG. 4 can also be used
to implement other processing operations and, as such, can be
modified for use at other processing stations within the processing
tool 310. For example, the reactor assembly 400 can be modified to
execute rinse/dry processes, etching processes, and electrochemical
processes (e.g., electropolishing, anodization, electroless
plating, electroplating, etc.). For such other processes, the
reactor base 410 may be modified to contain different chemistry
and/or different chemical delivery mechanisms.
[0051] FIG. 4 illustrates one embodiment of the reactor base 410
for depositing an EPE on the workpiece 316. In this embodiment, the
workpiece 316 is positioned with respect to the reactor base 410 so
that the side of the workpiece that is to be processed faces
downward in a generally horizontal plane. The particular reactor
base 410 shown in FIG. 4 can be functionally divided into four
subassemblies. A first subassembly 435 provides an environmentally
controlled reservoir of processing fluid. A second subassembly 440
is a fluid input/output region including channels and passageways
through which processing fluids flow to and from the reactor base
410. A third subassembly 445 is a deposition region in which the
photoresist or other electrophoretic solution/emulsion is deposited
onto the workpiece 316. The third subassembly 445 may include one
or more components that reduce and/or eliminate bubbles that can
cause pinhole formations in the deposited layer. A fourth
subassembly 450 is an in-situ secondary processing region in which
(a) the workpiece may be rinsed in-situ, (b) the workpiece holder
425 may be cleaned in-situ, or (c) other pre- or post-deposition
procedures can take place.
[0052] As illustrated, the first subassembly 435 includes an
emulsion tank 455 and a temperature control apparatus 460 disposed
in the tank 455. The temperature control apparatus 460 can be an
element that heats and/or cools the EPE chemistry in the tank 455
to a desired temperature for delivery to the deposition region
445.
[0053] The third subassembly 445 includes a bowl 485 above the
emulsion tank 455 and a cup 490 within the bowl 485. The bowl 485
can be a generally cylindrical member that concentrically surrounds
the cup 490. In the illustrated embodiment, the cup 490 has an
annular upper structure and a tapered, frusto-conical lower portion
497 that slopes downwardly and radially inwardly. The dimensions of
the bowl 485 may be similar to other types of reaction vessels used
in wet processing tools (e.g., electroless plating reactors,
etching reactors, rinse/dry capsules, etc.). As such, the reactor
400 is readily interchangeable with other reactors so that a single
processing tool frame may be used for a wide range of different
types of processes.
[0054] The reactor assembly 400 also includes a counter-electrode
495. As shown, the counter-electrode 495 is an annular ring. The
counter-electrode 495 is coupled to one or more electrical
connecting members to provide electrical power to the
counter-electrode 495. The counter-electrode 495 can alternatively
comprise a plurality of linear or curved segments positioned around
the processing cup 490 or other electrodes as set forth in U.S.
application Ser. Nos. 09/804,696; 09/804,697; and 09/872,151, all
of which are herein incorporated by reference.
[0055] In operation, the reactor assembly 400 electrochemically
deposits an EPR or other type of EPE onto the face of the workpiece
316. The electrochemical process includes lowering the reactor head
405 until the workpiece 316 contacts a flow of EPR at the top of
the cup 490. An electrical field is established in the EPR by
biasing a seed layer on the workpiece 316 at one potential and the
counter-electrode 495 at an opposite potential. The electrical
field between the seed layer on the workpiece 316 and the
counter-electrode 495 causes micelles in the EPR solution to become
attached to the surface of the workpiece 316. This is a self
limiting process because the deposited EPR does not conduct
electricity such that thin portions of the layer of the EPR
deposited on the workpiece 316 have a higher deposition rate than
thick portions. After a period of time, the thickness of the EPR
layer deposited on the workpiece 316 becomes highly uniform and
conforms to the topography of the workpiece 316.
[0056] D. Embodiments of Control Sequences
[0057] The control unit 346 (FIG. 3) can operate the processing
tool 310 (FIG. 3) to deposit an electrophoretic material onto a
workpiece in accordance with several different control sequences.
The control sequences generally provide automated deposition of
resists and other materials onto semiconductor wafers or other
types of micro-feature workpieces in a manner that can be
integrated with the other types of single-wafer processing
equipment used in patterning micro-features and depositing metals.
Several embodiments of such control sequences provide automated
substrate handling by maintaining a clean surface on the workpiece.
As such, the control sequence can use single-wafer handling
equipment compatible with stepper machines and other
microfabrication equipment.
[0058] FIG. 5 illustrates one processing sequence 550 of a number
of possible sequences. The particular sequences and parameters used
in the EPE deposition processes depend on the particular
manufacturing processes that are to be implemented. In the
illustrated embodiment of the processing sequence 550, the
processing tool 310 (FIG. 3) receives a microelectronic workpiece
from a cassette 317 (FIG. 3) and transfers it to one of the
processing stations. The processing sequence 550, for example, can
include a first fluid process 552, such as a pre-clean/pre-wetting
process, in a fluid processing station 324 (FIG. 3). In an
alternate embodiment, the processing sequence 550 can include a
seed layer repair/enhancement procedure before the first fluid
process 552 because it may be useful to enhance or otherwise
deposit additional conductive material onto the seed layer before a
pre-clean/pre-wetting process. Such enhancement or repair of the
seed layer may provide better photoresist film characteristics.
Methods and apparatus for processing a conductive seed layer are
shown and described in U.S. Pat. No. 6,197,181, which is
incorporated by reference herein.
[0059] After the pre-clean/pre-wetting process or other type of
first fluid process 552, the control system 346 causes the robotic
transfer mechanism 330 to remove the workpiece from the
pre-clean/pre-wetting station and transfer it to the
electrophoretic deposition station 311. At the electrophoretic
deposition station 311, the sequence 550 further includes a
deposition process 554 in which a negative electrophoretic resist
is deposited on the workpiece. The EPR deposition process 554 forms
a highly uniform conformal layer of negative resist even over large
three-dimensional structures with large step heights as shown above
in FIG. 2A. The specific parameters used in the deposition process
554 are input either directly or indirectly into the control system
346 by the user. It will be recognized that the particular
parameters depend on the EPE type, the size of the workpiece, the
type of underlying conductive layer, the thickness of the
photoresist layer desired, and several other parameters.
[0060] After completing the deposition process 554, the sequence
550 includes an in-situ rinse process 556 carried out in the
deposition station 311. This process reduces contamination of other
components because residual EPE is rinsed from the workpiece before
it is loaded onto the robot 330 (FIG. 3). Further, the control
system 346 may direct an in-situ contact cleaning operation at any
time. This process ensures consistent contact between the seed
layer and the electrical contacts that provide electroplating power
to the seed layer.
[0061] After the in-situ rinse process 556, the sequence 550
further includes a second fluid process such as a rinsing process
558. For example, the control system 346 directs the robotic
transfer mechanism 330 to remove the microelectronic workpiece from
the deposition station 311 and transfer it to a deionized water
rinse station for executing the rinsing process 558. After the
rinsing process 558, the workpiece can be removed from the tool 310
for subsequent processing. In an alternate embodiment, the sequence
can optionally include a thermal process 559. For example, the
control system 346 may also be programmed to direct the workpiece
to a station at which the thermal process 559 is executed after
completing the rinsing process 558. The thermal process 559 may
include both heating and subsequent cooling of the workpiece to
effectively cure the photoresist. When the thermal process 559
occurs in the tool 310, the workpiece can be removed from the tool
310 after baking and cooling the resist. As explained in more
detail below, the workpiece is typically processed in additional
tools for further processing the resist or other electrophoretic
material deposited on the workpiece.
[0062] The control sequence 550 can further include an exposure
procedure 560 followed by a photoresist development procedure 562
to create the openings in the negative resist layer for exposing
the deposition areas 252 (FIG. 2C) on the seed layer 250 (FIG. 2C).
Although the exposure procedure 560 and the development procedure
562 may be performed in the processing tool 310 (FIG. 3), these
procedures are generally executed in separate tools. After the
exposure procedure 560 and the development procedure 562, the
microelectronic workpieces may be transferred back to the
processing tool 310 for a metallization plating procedure 564 to
form the features 270 (FIG. 2F). As shown at stage 566, the overall
process may be repeated as necessary until the desired structures
are formed in or on the substrate.
[0063] E. Additional Embodiments of Processing Station Layouts
[0064] FIGS. 6-8 illustrate additional layouts for processing
stations in EPE deposition tools in accordance with other
embodiments of the invention. With specific reference to FIG. 6,
tool 310a comprises EPE deposition stations 311, the load/unload
station 318, one or more first fluid processing stations 332, and
one or more second fluid processing stations 334. The fluid
processing stations 332 and 334 may execute one or several process
sequences, such as pre-wetting the workpiece prior to EPR
deposition, cleaning the workpiece subsequent to EPR deposition,
developing the EPR coating following patterning, depositing
metallization on the workpiece, enhancing the seed layer prior to
either EPR deposition or metallization deposition, and so
forth.
[0065] The workpieces are transferred between the processing
stations 311, 332 and 334 using one or more robotic transfer
mechanisms 336 and 338 that are disposed for linear movement along
a central track 328. All of the processing stations, as well as the
robotic transfer mechanism, are disposed in a cabinet, such as the
one shown in FIG. 3. The cabinet can be provided with filtered air
at a positive pressure to thereby limit airborne contaminants that
may reduce the effectiveness of the workpiece processing. To
further limit cross-contamination between processing stations, the
robotic transfer mechanisms 336 and 338 may be dedicated to
specific processing stations.
[0066] FIG. 7 illustrates another embodiment of a processing tool
310b in which a processing station 340 is located in a separate
portion of the integrated tool set. Unlike the embodiment of FIG.
6, at least one processing station in the tool 310b is serviced by
a dedicated robotic mechanism 342. The dedicated robotic mechanism
342 accepts workpieces that are transferred to it by the robotic
transfer mechanisms 336 and/or 338. Transfer may take place through
an intermediate staging area 344. As such, it becomes possible to
separate one portion of the workpiece processing tool, such as a
thermal processing station 345, from other portions of the tool.
Additionally, the processing station serviced by the dedicated
robot 342 may be implemented as a separate module that is attached
to upgrade an existing tool set. In another embodiment, the
processing station 340 can be placed between the load/unload
station 318 and the remainder of the processing tool 310a. In which
case, the dedicated robot 342 may also transfer workpieces from the
load/unload station 318 to an intermediate staging area 344. It
will be recognized that other types of processing stations may be
serviced by the dedicated robot 342.
[0067] Other types of processing tool layouts may also be used. For
example, in certain tools sold under the brand name Equinox.TM.
available from Semitool, of Kalispell, Mont., the processing
stations are disposed radially about a centrally located robotic
transfer mechanism and a load/unload station. As illustrated in
FIG. 8, for example, a radial tool 310c may include the same basic
processing stations and robotic transfer apparatus similar to the
linear tool.
[0068] From the foregoing, it will be appreciated that specific
embodiments of the invention have been described herein for
purposes of illustration, but that various modifications may be
made without deviating from the spirit and scope of the invention.
Accordingly, the invention is not limited except as by the appended
claims.
* * * * *