U.S. patent application number 15/218804 was filed with the patent office on 2016-11-17 for circuit-on-wire (cow).
The applicant listed for this patent is Sharp Laboratories of America, Inc.. Invention is credited to Themistokles Afentakis, Apostolos Voutsas.
Application Number | 20160336350 15/218804 |
Document ID | / |
Family ID | 53755504 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160336350 |
Kind Code |
A1 |
Voutsas; Apostolos ; et
al. |
November 17, 2016 |
Circuit-on-Wire (CoW)
Abstract
A circuit-on-wire (CoW) is provided that is made from a flexible
metal wire with an outer surface, and a plurality of discrete
electrical control devices formed in series along the metal wire
outer surface. Each control device may have an electrical contact
accessible through the metal wire. In one aspect, the control
device may have a via through the metal wire from the top surface
to the bottom surface with a second electrical contact accessible
through the via. In addition, the control devices may have a top
surface with an accessible third electrical contact. For example,
the control device may be a first thin-film transistor (TFT), with
a gate electrode accessible through the metal wire, wherein the
second electrical contact is a first source/drain (S/D) electrode,
and wherein the third electrical contact is a second S/D electrode.
Using the above-described CoW, a woven active matrix array can be
fabricated.
Inventors: |
Voutsas; Apostolos;
(Portland, OR) ; Afentakis; Themistokles; (Camas,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sharp Laboratories of America, Inc. |
Camas |
WA |
US |
|
|
Family ID: |
53755504 |
Appl. No.: |
15/218804 |
Filed: |
July 25, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14169202 |
Jan 31, 2014 |
9425221 |
|
|
15218804 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 27/1262 20130101;
H01L 21/31105 20130101; H01L 21/76897 20130101; H01L 29/42384
20130101; H01L 27/124 20130101; H01L 27/1259 20130101; H01L 23/5387
20130101; H01L 27/1255 20130101; H01L 29/41733 20130101; H01L
27/1248 20130101; H01L 27/1218 20130101 |
International
Class: |
H01L 27/12 20060101
H01L027/12; H01L 21/768 20060101 H01L021/768; H01L 21/311 20060101
H01L021/311 |
Claims
1. A circuit-on-wire (CoW) comprising: a flexible metal wire with
an outer surface; and a plurality of discrete electrical control
devices formed in series along the metal wire outer surface.
2. The CoW of claim 1 wherein a plurality of the control devices
each comprise at least a first electrical contact accessible
through the metal wire.
3. The CoW of claim 1 wherein the metal wire comprises an outer top
surface and an outer bottom surface; wherein a plurality of the
control devices each comprise: a via through the metal wire from
the top surface to the bottom surface; and, a second electrical
contact accessible through the via.
4. The CoW of claim 3 wherein a plurality of the control devices
each further comprise a top surface with an accessible third
electrical contact.
5. The CoW of claim 4 wherein a plurality of the control devices
are each a first thin-film transistor (TFT), with a gate electrode
accessible through the metal wire, wherein the second electrical
contact is a first source/drain (S/D) electrode. and wherein the
third electrical contact is a second S/D electrode.
6. The CoW of claim 4 wherein a plurality of the control devices
are each a pixel switching element comprising: a first TFT, with a
gate electrode accessible through the metal wire, wherein the
second electrical contact is a first S/D electrode, and wherein the
third electrical contact is a second S/D electrode; a storage
capacitor connected to the second S/D electrode of the first TFT; a
second TFT comprising: a via through the metal wire from the top
surface to the bottom surface; a first S/D electrode accessible
through the via; a gate electrode connected the second S/D
electrode of the first TFT; and, a second S/D electrode.
7. canceled
8. The CoW of claim 1 further comprising: a spool; and, wherein the
metal wire is wound around the spool.
9. The CoW of claim 8 further comprising: a plurality of adjacent
metal wires wound around the spool, each metal wire including a
plurality of discrete electrically active control devices formed in
series along its outer surface.
10. canceled
11. A woven active matrix array comprising: a set of parallel first
metal lines aligned in a first direction; a set of parallel second
metal lines aligned in a second direction orthogonal to the first
direction; wherein the first metal lines intersect the second metal
lines to form pixel regions; wherein a plurality of metal lines
from the second metal lines comprise serially configured
circuit-on-wire (CoW) control devices overlying an outer surface of
the second metal line; and, wherein each control device is
associated with a corresponding pixel region.
12. The array of claim 11 wherein a plurality of control devices
each comprises at least a first electrical contact accessible
through the second metal wire.
13-19. canceled
20. The array of claim 11 wherein the second metal wire further
comprises: an insulation layer overlying the second metal wire top
and bottom surfaces, selectively etched to expose control device
electrodes.
21. The array of claim 11 wherein a plurality of metal lines from
the first metal lines comprise serially configured CoW control
devices overlying an outer surface of the first metal line.
22. canceled
23. A method for forming a woven active matrix array, the method
comprising: providing a substrate with a top surface; forming a set
of parallel first metal lines aligned in a first direction
overlying the substrate top surface; forming a set of parallel
second metal lines aligned in a second direction orthogonal to the
first direction, overlying the first metal lines; forming pixel
regions between first and second metal line intersections; wherein
a plurality of metal lines from the second metal lines comprise
serially configured circuit-on-wire (CoW) control devices overlying
an outer surface of the second metal line, and wherein each control
device is associated with a corresponding pixel region.
24. The method of claim 23 further comprising: forming a pixel
device in each pixel region; and, forming electrical contacts
between each pixel device and a corresponding control device.
25. The method of claim 23 wherein forming the second metal lines
includes forming second metal lines having insulated top and bottom
surfaces, selectively etched to expose control device electrodes;
the method further comprising: prior to forming the second metal
lines, depositing an electrically conductive adhesive overlying the
first metal lines; and, subsequent to forming the second metal
lines, forming electrical contacts between the first metal lines
and the control device electrodes.
26. A method for forming circuit-on-wire (CoW), the method
comprising: forming an electrically conductive metal wire; and,
forming a series of discrete control devices overlying the metal
wire.
27. The method of claim 26 wherein forming the series of discrete
control devices includes forming thin-film devices using film
deposition and photolithographic etching steps.
28. The method of claim 26 wherein forming the series of discrete
control devices includes forming a plurality of control devices
each having an electrode electrically connected to the metal
wire.
29-30. canceled
31. The method of claim 26 wherein forming the series of discrete
control devices includes forming a plurality of control devices
each comprising: an electrode on a metal wire top surface; and, a
via from the metal wire top surface to a metal wire bottom surface,
electrically connected to the electrode.
32. The method of claim 26 wherein forming the series of discrete
control devices includes forming control devices selected from a
group consisting of thin-film transistors (TFTs), thin-film diodes,
pixel switching elements, and combinations of the above-mentioned
devices.
Description
RELATED APPLICATIONS
[0001] This application is a Continuation of an application
entitled, CIRCUIT-ON-WIRE, invented by Apostolos Voutsas et al.,
Ser. No. 14/169,202, filed Jan. 31, 2014, attorney docket No.
SLA3377, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention generally relates to display fabrication and,
more particularly, to a circuit-on-wire (CoW) technology generally
useful. in the fabrication of large array electronic panels.
[0004] 2. Description of the Related Art
[0005] The fabrication of backplane arrays for various types of
flat panel displays, such as liquid crystal display (LCD) or
organic light emitting diode (OLED), requires multiple deposition
and photolithographic patterning (selective etching) steps. These
steps must take place using specialized process equipment capable
of handling the substantial size of the substrates typically used
for display manufacturing. In that sense, the manufacturing cost is
a function of the substrate area and, hence, tends to increase
geometrically with the display size [i.e. manufacturing
cost.about.(display diagonal).sup.2]. In order to achieve a lower
product cost, manufacturing costs must be minimized. This fact is
especially evident in the case of large displays, which have become
increasingly ubiquitous in everyday life--from home TVs, to
information and advertising digital signs.
[0006] Another important issue in display backplane fabrication is
optical transparency. High optical transparency is desirable for
improving display appearance (i.e. brightness) and, ultimately, for
enabling a visually transparent panel that can seamlessly integrate
with its surroundings and function harmoniously within its
operating environment.
[0007] FIG. 1 is a plan view of a thin-film transistor (TFT) active
matrix array backplane (prior art). The backplane consists of a
plurality of pixel elements formed by the intersecting horizontal
(gate) and vertical (data) metal lines. These pixel elements host a
number of sub-components (mostly thin film transistors and
capacitor elements), which function to determine the "state" of the
pixel--in other words, how much light is allowed through the pixel
area to reach an observer. For a highly transparent display, which
one can "see through" when not displaying an image, it is desirable
that the majority of the pixel area be void of any components that
may obstruct the passage (transmission) of visible light. For
example, referring to FIG. 1B, it is desirable to maximize the
"active" area and minimize the "dead zone" area. Note: although a
display backplane is depicted, the same issues apply to an active
matrix array that receives and processes light, such as a
charge-coupled device (CCD) camera.
[0008] FIG. 2 is a plan view of a typical LCD pixel structure
(prior art) In terms of fabrication, pixels--consisting of the
intersecting metal lines and the internal subcomponents--are
constructed by a succession of thin-film material formation (e.g.
deposition) steps and feature-patterning steps by subtractive
processing (e.g. combination of photolithography and etching
steps). The pixel size is determined by the desired resolution of
the panel, expressed in pixels-per-inch (PPI). For example, a 50
PPI panel consists of 508.times.508 micron (.mu.m) pixels, while a
150 PPI panel consists of 169.times.169.mu.m pixels. For a
full-color display, the pixel is further divided into
sub-pixels--in the simplest case one sub-pixel for each of (R)ed,
(G)reen and (B)lue). As a result, the ultimate sub-pixel size is
given (in .mu.m) by the formula: 25400/(3PPI), where PPI refers to
the target panel resolution. In the ideal case, all the pixel area
contributes to light transmission, but practically, only a portion
of the pixel area actually transmits light. As shown in FIG. 2 for
example, light transmission is blocked by the capacitor(s), TFT(s),
and width of metal wires (horizontal & vertical). The area of
these components tends to scale with the overall pixel area. For
very small pixels, the effective pixel area (expressed often by the
term aperture ratio) tends to become prohibitively small. For a
high quality transparent display, aperture ratios (the ratio of
transmissive area to total pixel area) of more than 85% are
typically demanded.
[0009] It would be advantageous if a means existed for fabricating
an active matrix array with a larger aperture ratio. It would also
be advantageous if this fabrication means permitted the active
matrix arrays to be produced at a lower cost.
SUMMARY OF THE INVENTION
[0010] Disclosed herein is an apparatus and method of manufacture
that permits pixel subcomponents to be moved from the pixel
transmissive area, as is conventional, to the pixel's metal wiring
frame. In doing so, two key objectives are accomplished. First,
manufacturing costs are reduced by preparing the circuit-on-wire
off-line, and then "weaving" it onto the panel using a simplified
assembly scheme. This process allows the manufacturing cost to
scale with the length of the panel, as opposed to the area of the
panel. Second, the use of the circuit-on-wire (CoW) significantly
improves (increases) the pixel aperture ratio, and, ultimately
achieves a sufficiently high pixel aperture to evoke the feeling of
transparency.
[0011] The notion of an effective transparent display implicitly
requires an emissive technology to be achieved. In other words, a
liquid crystal display (LCD) embodiment is limited in its capacity
to achieve a high quality transparent display--mostly due to the
necessity of having a pair of crossed polarizers at the two sides
of the LCD module that block almost half of the outgoing light. On
the other hand, a display enabled by light emitting diodes (LEDs),
either organic or inorganic, can provide a much more effective path
to transparency if the effective pixel area can be sufficiently
enlarged, since polarizers are not required.
[0012] Accordingly, a CoW is provide that is made from a flexible
metal wire with an outer surface, and a plurality of discrete
electrical control devices formed in series along the metal wire
outer surface. Each control device may have a first electrical
contact accessible through the metal wire. In one aspect, the metal
wire has an outer top surface and an outer bottom surface. Then,
the control device may have a via through. the metal wire from the
top surface to the bottom surface with a second electrical contact
accessible through the via. In addition, the control devices may
have a top surface with an accessible third electrical contact. For
example, the control device may be a first thin-film transistor
(TFT), with a gate electrode accessible through the metal wire,
with the second electrical contact being a first source/drain (S/D)
electrode, and the third electrical contact being a second S/D
electrode.
[0013] Using the above-described CoW, a woven active matrix array
may be fabricated, made from a set of parallel first metal lines
aligned in a first direction and a set of parallel second metal
lines aligned in a second. direction orthogonal to the first
direction. The first metal lines intersect the second metal lines
to form pixel regions. A plurality of metal lines from the second
metal lines are made with serially configured CoW control devices
overlying an outer surface of the second metal line, with each
control device being associated with a corresponding pixel
region.
[0014] Additional details of the above-described devices as well as
fabrication methods are provided in more detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a plan view of a thin-film transistor (TFT) active
matrix array backplane (prior art).
[0016] FIG. 2 is a plan view of a typical LCD pixel structure
(prior art).
[0017] FIG. 3 is a partial cross-sectional view of a
circuit-on-wire (CoW).
[0018] FIG. 4 is a plan view of a pixel switching element control
device.
[0019] FIGS. 5A and 5B depict two variations of CoW packaging.
[0020] FIG. 6 is a plan view of a woven active matrix array.
[0021] FIG. 7 is a plan view depicting a variation in the active
matrix array of FIG. 6.
[0022] FIGS. 8A and 8B are, respectively, plan and cross-sectional
views of a CoW control device repeated unit.
[0023] FIG. 9 is a plan view of an active matrix array with
repeated units.
[0024] FIGS. 10A and 10B are, respectively, schematic and
perspective diagrams of a pixel switching element for use with an
LED type of pixel.
[0025] FIGS. 11A through 11E are partial cross-sectional views of
the CoW pixel switching element of FIG. 10B.
[0026] FIG. 12 is a flowchart illustrating a method for forming a
CoW.
[0027] FIG. 13 is a flowchart illustrating a method for forming a
woven active matrix array.
DETAILED DESCRIPTION
[0028] FIG. 3 is a partial cross-sectional view of a
circuit-on-wire (CoW). The CoW 300 comprises a flexible metal wire
302 with an outer surface 304. A plurality of discrete electrical
control devices are formed in series along the metal wire outer
surface 304. Shown are control devices 306-0 through 306-n, where n
is an integer not limited to any particular value. In one aspect,
the control devices, e.g., device 306-0, comprise a first
electrical contact 308-0 accessible through the metal wire 302.
Typically, the metal wire 302 is electrically conductive.
Alternatively, some or all of the control devices may be
electrically isolated from the metal wire 302.
[0029] In one aspect, the metal wire may be said to comprise an
outer top surface 304a and an outer bottom surface 304b. For
example, the metal wire 302 is relatively flat or oval in its
cross-section (not shown). A plurality of control devices, e.g.,
control device 306-1, may comprise a via 310-1 through the metal
wire from the top surface 304a to the bottom surface 304b, and a
second electrical contact 312-1 accessible through the via. In
another aspect, a plurality of control devices, e.g., control
device 306-n, each further comprise a top surface 314-n with an
accessible third electrical contact 316-n. For example, control
device 306-n may be a first thin-film transistor (TFT), with a gate
electrode 308-n accessible through the metal wire 302, with the
second electrical contact 312-n being a first source/drain (S/D)
electrode (or a contact in electrical communication with. the first
S/D electrode), and the third electrical contact 316-n being a
second S/D electrode (or a contact in electrical communication with
the second S/D electrode). Typically, an insulation layer 318
overlies the metal wire top 304a and bottom surfaces 308b, and is
selectively etched to expose control device electrodes. In one
aspect, the etching is performed during CoW fabrication.
Alternatively, the etching may be performed as the CoW is
integrated into a higher assembly.
[0030] It should be understood that the sequential control devices
may be the same or different types of devices. In one aspect, some
of the devices need not be active. As explained in more detail
below, a collection of control devices may be grouped in repeated
units, where each repeated unit may be associated with a
manufacturing sub-component, such as an active matrix array
pixel.
[0031] FIG. 4 is a plan view of a pixel switching element control
device. The pixel switching element 400 comprises a first TFT 402,
similar to control device 306-n of FIG. 3, with a gate electrode
404 (in phantom) accessible through the metal wire 302, the second
electrical lE contact 406 being a first SID electrode with a via
407 (in phantom) connected to the bottom side of the wire, and the
third, exposed electrical contact 408 being a second S/D electrode.
A storage capacitor 410 is connected to the second SID electrode
408 of the first TFT. A second TFT 412 comprises a via 414 through
the metal wire 302 from the top surface 304a to the bottom surface
304b. A first SID electrode 416 is accessible through the via 414.
A gate electrode 418 is connected the second S/D electrode 408 of
the first TFT. The second TFT 412 further comprises a second S/D
electrode 420. The pixel switching element is one example of a.
complete or partial repeated unit, described in more detail
below.
[0032] FIGS. 5A and SB depict two variations of CoW packaging. In
FIG. 5A the metal wire 302 with control devices 306 is wound around
a spool 500, permitting the wire to be unwound, sectioned, and/or
laid flat during use at a higher assembly. In FIG. 5B, a plurality
of adjacent. metal wires 302-0 through 302-j are shown, where j is
an integer greater than 1, wound around the spool 500. Each metal
wire 302-0 through 302-j includes a plurality of discrete
electrically active control devices 306 formed in series along its
outer surface. Advantageously, this spooling permits the
simultaneous deployment of a plurality of metal lines for the
purpose, for example, of an active array fabrication. In comparing
particular wires 302-0 through 302-j, the control devices thereon
need not necessarily be identical. Further, even if the device, and
the order of the devices 306 is identical, the alignment of devices
between wires may or may not be staggered.
[0033] The spool of FIG. 5A is attractive for relatively small
roll-to-roll (R-2-R) machine operations, while the spool of FIG. 5B
is more applicable to the creation of large web lines used with a
process performed on very large sheets. For sheet-to-sheet
operation, thousands of wires can be formed on a large sheet,
despoiled, and then cut to generate long strips that can be laid
down to make arrays. The advantage in this case factor, as a
typical array has much empty space where the pixels are eventually
formed.
[0034] FIG. 6 is a plan view of a woven active matrix array. The
array 600 comprises a set of parallel first metal lines 602-0
through 602-p, where p is an integer greater than 1, aligned in a
first direction 604. A set of parallel second metal lines 606-0
through 606-r, where r is an integer greater than 1, is aligned in
a second direction 608 orthogonal to the first direction 604. The
first metal lines 602 intersect the second metal lines 606 to form
pixel regions 610. A plurality, or all of the metal lines from the
second metal lines 606-0 through 606-r comprise serially configured
CoW control devices 306 overlying an outer surface of the second
metal line as described above in the explanation of FIGS. 3 and 4.
Each control device 306 is typically associated with a
corresponding pix 610. For example, control device 306-0 is
associated with pixel region 610-0. Details of the control devices
have been presented above, and are not repeated here in the
interest of brevity. In the case of the pixel switching element of
FIG. 4 for example, a pixel device such as an LED or charge-coupled
sensor (not shown) is connected to the second SID electrode of each
second TFT.
[0035] The first metal lines 602-0 through 602-p may be gate lines,
and the second metal lines 606-0 through 606-r may be data lines,
as shown. Alternatively, the first metal lines 602-0 through 602-p
may be data lines, and the second metal lines 606-0 through 606-r
may be gate lanes. In another aspect not shown, both the gate and
control lines may be CoW, with control devices. The array 600 may
be formed on a transparent substrate 612 as shown. In one aspect,
the transparent substrate is flexible, so that the entire array,
including the substrate, can be spooled. for delivery for higher
assembly processing.
[0036] FIG. 7 is a plan view depicting a variation in the active
matrix array of FIG. 6. In this aspect a set of parallel power
metal lines 700-0 through 700-p are aligned in the first direction
604, and alternating with the first metal lines 602-0 through
602-p. In the case of at least some of the control devices being
the pixel switching elements described above in the explanation of
Fig.4, each second TFT first S/D electrode may be connected to an
underlying power metal line through the via (see FIG. 10B). The
first metal lines 602-0 through 602-p may be gate lines, and the
second metal lines 606-0 through 606-r may be data lines, as shown.
Alternatively, the first metal lines 602-0 through 602-p may be
data line and the second metal lines 606-0 through 606-r may be
gate lines. In another aspect not shown, both the gate and control
lines may be CoW, with control devices.
[0037] FIGS. 8A and 8B are, respectively, plan and cross-sectional
views of a CoW control device repeated unit. The metal wire 302 may
have a rectangular cross section with width 800 in the range of 10
.mu.m to 1 mm, and thickness 802 in the range of 10 .mu.m to 100
.mu.m. The wire 302 may, for example, be made of stainless steel,
Al, Cu, Ni, Mo, or any of their alloys. Circuit and device blocks
may be fabricated directly on the surface of the metal wire 302.
Some of these blocks may be interconnected on the same metal wire
or connected to other components (off of the metal wire).
Through-holes or vias may be formed on the metal wire to facilitate
such connections. The features formed on the surface of the wire
may comprise repeated units 804.
[0038] FIG. 9 is a plan view of an active matrix array with
repeated units. One application for metal wires with CoW repeated
units is for backplane arrays. In that case, the electronic circuit
that controls the operation of a pixel is the repeated unit 804.
The extent of the repeated unit is then bound by the size of the
pixel. The spacing between repeated units is determined by the
pixel pitch (PPI). Taking the example of a 50 PPI backplane, the
pixel size is calculated to be 508 .mu.m. In this case, the pixel
controlling circuit needs to be integrated within a wire length of
less than 508 .mu.m, and the repeated unit pitch is 508 .mu.m.
[0039] Although CoW devices and circuits are shown as fabricated on
gate wires, there is no real restriction as to which wire bears
circuit elements, or that such elements must exist on only one type
of wire. These choices depend primarily on the type of control
circuits needed and tradeoffs between ease of integration and
manufacturing cost.
[0040] FIGS. 10A and 10B are, respectively, schematic and
perspective diagrams of a pixel switching element for use with an
LED 1000 type of pixel. The pixel switching element 400 is one
example of a repeated unit. The pixel switching element 400 is laid
out on the metal wire 602 (gate wire) that supplies the transistor
gate-controlling signal. This circuit utilizes connections to two
more wires, a wire 700 carrying a power signal and a wire 606
carrying a data signal to enable the proper operation of the pixel.
Preferable, all device and circuit blocks are fabricated on a
single wire in order to simplify the overall fabrication process.
In the specific example of FIGS. 10A and 10B, only the gate wire
needs to be fabricated with CoW control devices.
[0041] FIGS. 11A through 11E are partial cross-sectional views of
the CoW pixel switching element of FIG. 10B. The switch TFT 412,
drive TFT 402, and capacitor 410 are primarily located on the
surface of the gate wire 602 and are fabricated during the
preparation of the gate wire (offline to the panel assembly). The
three principal metal wires (gate 602, data 606, and power 700) are
laid out on the backplane substrate and other materials are used to
ensure electrical connections between wires, as needed. For
example, a conductive adhesive 1100 may be used to provide
electrical connection between data wire 606 and gate wire 602, LED
electrode 1000 and gate wire 602, and power wire 700 and gate wire
602. The LED electrode 1000 can be formed by solution processing
printing) methods, and the conductive adhesive 1100 can be ink-jet
printed at various steps of the backplane assembly process.
Alternatively, LED elements can be fabricated prior to the assembly
of the various wires to form the controlling active matrix
array.
[0042] FIG. 12 is a flowchart illustrating a method for forming a
CoW. Although the method is depicted as a sequence of numbered
steps for clarity, the numbering does not necessarily dictate the
order of the steps. It should be understood that some of these
steps may be skipped, performed in parallel, or performed without
the requirement of maintaining a strict order of sequence.
Generally however, the method follows the numeric order of the
depicted steps. The method starts at Step 1200.
[0043] Step 1202 forms an electrically conductive metal wire and
Step 1204 forms a series of discrete control devices overlying the
metal wire. Typically, Step 1204 forms the series of discrete
control devices includes using film deposition and
photolithographic etching steps. The discrete control devices
formed in Step 1204 may include a plurality of control devices each
having an electrode electrically connected to the metal wire.
Alternatively, the control devices may have electrodes that are
electrically isolated from the metal wire. Some examples of control
devices include TFTs, thin-film diodes, pixel switching elements,
resistors, capacitors, inductors, and combinations of the
above-mentioned devices.
[0044] In one aspect, forming the series of discrete control
devices in Step 1204 includes substeps. Step 1204a forms an
electrode on a metal wire top surface. Step 1204b forms a via from
the metal wire top surface to a metal wire bottom surface,
electrically connected to the electrode. In another aspect, Step
1206 forms an insulation layer overlying the control. devices. Step
1208 selectively etches the insulation layer to expose electrodes
from a plurality of control devices.
[0045] FIG. 13 is a flowchart illustrating a method for forming a
woven active matrix array. The method begins at Step 1300. Step
1302 provides a substrate with a top surface. Step 1304 forms a set
of parallel first metal lines aligned in a first direction
overlying the substrate top surface. Step 1306 forms a set of
parallel second metal lines aligned in a second direction
orthogonal to the first direction, overlying the first metal lines.
Step 1308 forms pixel regions between first and second metal line
intersections. With respect to Step 1306, a plurality of metal
lines from the second metal lines comprise serially configured CoW
control devices overlying an outer surface of the second metal
line, where each control device is associated with a corresponding
pixel region. Step 1310 forms a pixel device in each pixel region.
Step 1312 form electrical contacts between each pixel device and a
corresponding control device.
[0046] In one aspect, forming the second metal lines in Step 1306
includes forming second metal lines having insulated top and bottom
surfaces that are selectively etched to expose control device
electrodes. Then, prior to forming the second metal lines, Step
1305 deposits an electrically conductive adhesive overlying the
first metal lines. Subsequent to forming the second metal lines,
Step 1307 forms electrical. contacts between the first metal lines
and the control device electrodes.
[0047] CoW control devices, a woven active matrix array, and
corresponding fabrication processes have been provided. Examples of
particular devices, interconnections, pixel types, and process
steps have been presented to illustrate the invention. However, the
invention is not limited to merely these examples. Other variations
and embodiments of the invention will occur to those skilled in the
art.
* * * * *