Liquid crystal display device with separated anode oxide electrode

A first electrode 1 comprises an anode oxide electrode 5, a lower electrode 2 and signal electrodes, wherein the signal (electrodes are connected to each other by the anode oxide electrode when the anodic oxidation treatment is performed, while a second electrode comprises an upper electrode on a nonlinear resistor layer, a display electrode connected to the upper electrode, and a connecting electrode covering a part of the anode oxide electrode, wherein the lower electrode, the nonlinear resistor layer and the upper electrode constitute the nonlinear resistor, and wherein a part of the anode oxide electrode is separated at the side thereof which is also a side of the connecting electrode comprising the second electrode, thereby forming independent signal electrodes. This can prevent the nonlinear resistor from being deteriorated in characteristic in the step involved in generation of static electricity such as a step of printing an orientational film onto a first substrate having the nonlinear resistor or a step of performing orienting process, thereby obtaining uniform and stable characteristic.

TECHNICAL FIELD 
The present invention relates to a monochrome or color liquid crystal 
display device which has been widely employed as a display device of a 
watch, a pocket calculator, a video camera, and a variety of electronic 
devices. Particularly, it relates to the structure of a liquid crystal 
display device having first and second electrodes which are disposed on 
one of two substrates between which a liquid crystal is filled, and also 
having an anode oxide film of the first electrode formed between the first 
and second electrodes as a nonlinear resistor layer, thereby forming a 
nonlinear resistor having a structure of "metal-insulating film-metal" or 
"metal-insulating film-transparent conductor" between the first and second 
electrodes. 
BACKGROUND TECHNOLOGY 
A display capacity of a liquid crystal display device using a liquid 
crystal display has been recently increased. 
In a simple matrix structured liquid crystal display device employing a 
multiplex driving system, a contrast is dropped or a response speed is 
reduced as the speed of a time sharing is increased. Accordingly, if the 
liquid crystal display device has about 200 scanning lines, it is 
difficult to obtain a sufficient contrast. 
Accordingly, there has been employed an active matrix system liquid crystal 
display panel having switching elements in each pixel to remove such 
drawbacks. 
In the active matrix system liquid crystal display system, there are two 
types, one is a three terminal system employing thin film transistors 
(hereinafter referred to as "TFT") as switching elements and the other is 
two terminal system employing nonlinear resistors. The two terminal system 
is superior to the three terminal system since the former is simple in 
structure and a method of manufacturing thereof. 
A diode type, a varistor type, a thin film diode (hereinafter referred to 
as "TFD") type and so on are developed as the two terminal system. 
Among these types, the TFD type is simple in structure and has few 
manufacturing steps. 
Further, the liquid crystal display panel is required to display with high 
density and high definition, and the switching elements require reduction 
of the area they occupy. 
As a means for permitting the liquid crystal display panel to display with 
high density and high definition, a photo-lithography technique and an 
etching technique which are micro processing techniques in semiconductor 
production techniques are used. However, even if such semiconductor 
production techniques are employed, it is very difficult to realize a 
large area processing with low cost. 
The structure of a conventional liquid crystal display device having a 
switching element which efficiently makes the area larger with low cost 
will be now described with reference to FIG. 45 which is a plan view 
showing an example of a conventional liquid crystal display device, FIG. 
47 which is a plan view enlarging a part thereof and FIG. 46 which is a 
cross sectional view taken along the line X--X in FIG. 45. 
The liquid crystal display device comprises, as shown in FIG. 47, a first 
substrate 1, a second substrate 11 which are made of a transparent 
material and oppose each other by way of a spacer 17 at a certain gap, and 
a liquid crystal 16 which is filled between the first and second 
substrates 1 and 11. 
A lower electrode 2 and a signal electrode 4 are disposed on the first 
substrate 1 as a first electrode, and a nonlinear resistor layer 3 is 
provided on the lower electrode 2. Further, an upper electrode 6 as a 
second electrode is provided on the nonlinear resistor layer 3 so is to 
overlap, thereby constituting a nonlinear resistor 9. The upper electrode 
6 as the second electrode extends from a display electrode 7 as shown in 
FIG. 46, and a part of the upper electrode 6 also serves as the display 
electrode 7. 
The nonlinear resistors 9 and the display electrodes 7 are disposed in a 
matrix shape. 
A black matrix 12 is disposed on the second substrate 11 at a part 
confronting the first substrate 1 as shown by the hatched line in FIG. 46 
for preventing leaking of light from gaps defined in the display 
electrodes 7 disposed on the first substrate 1. That is, the black matrix 
12 is disposed on a non-display portion as a shading portion. 
An opposed electrode 13 is disposed on the second substrate 11 in a belt 
shape by way of an interlayer insulating film 14 so as to oppose the 
display electrode 7 as shown in FIG. 47 so that the opposed electrode 13 
is not short circuited, without contact with the black matrix 12. 
In FIG. 46, the lower electrode 2 and the signal electrode 4 serving as the 
first electrode, and the upper electrode 6 and the display electrode 7 
serving as the second electrode, disposed on the first substrate 1, are 
shown by broken lines, wherein the illustration of the nonlinear resistor 
layer 3 is omitted, and the black matrix 12 and the opposed electrode 13 
under the second substrate 11 are shown by solid lines. 
The lower electrode 2 disposed on the first substrate 1 extends from the 
signal electrode 4 so as to constitute the nonlinear resistor 9, and the 
lower electrode 2 serving as an overhanging region overlaps the upper 
electrode 6 to constitute the nonlinear resistor 9. 
The signal electrode 4 as the first electrode and the display electrode 7 
as the second electrode are spaced at a certain gap d as shown in FIG. 46. 
The display electrode 7 is disposed to overlap the opposed electrode 13 by 
way of the liquid crystal 16, thereby forming pixel portions of the liquid 
crystal display panel. 
The black matrix 12 is provided to overlap a region forming the display 
electrode 7 to a given amount, thereby serving to prevent leaking of light 
from a peripheral region of the display electrode 7. 
The liquid crystal display device performs a given image display owing to 
the change of transmittance of the liquid crystal 16 in a region where the 
black matrix 12 is not provided on the display electrode 7. 
Further, orientational films 15 and 15 are provided between the first 
substrate 1 and the second substrate 11 at parts confronting the first 
substrate 1 and the second substrate 11 as processing layers for regularly 
aligning molecules of the liquid crystal 16. 
As shown in FIG. 45, the signal electrodes 4 in M rows are disposed on the 
first substrate 1 while the opposed electrodes 13 or data electrodes in N 
columns are disposed on the second substrate 11 so as to structure the 
liquid crystal display device having a display region 18 formed of a 
matrix in M rows and N columns as shown by one dot chain line. 
The display electrodes 7 are provided at an intersection between the signal 
electrodes 4 in M rows and the opposed electrodes 13 or data electrodes in 
N columns, and the nonlinear resistors (TFD in this example) 9 are 
provided between the signal electrodes 4 and the display electrodes 7. 
An anode oxide electrode (anodizing electrode) 5 for connecting the signal 
electrode 4 in M rows with each other is disposed on the first substrate 
1, and connecting electrodes 8 for connecting the signal electrodes 4 with 
an external circuit are provided at a portion opposite to the anode oxide 
electrode 5. 
In such a manner, the signal electrodes 4 in each column are connected to 
each other by the anode oxide electrode 5, and the lower electrodes 2 
connected to the signal electrodes 4 are at once subject to an anodic 
oxidation treatment so as to form the nonlinear resistor 3 on the surface 
of the lower electrodes 2 (FIG. 47), but the signal electrodes 4 in each 
column are separated from and independent of each other upon completion of 
the anodic oxidation treatment. 
Accordingly, as shown in FIG. 45, the anode oxide electrode 5 has a cut 
portion 62 which extends outside of a separation line 34 (shown by a 
broken line) of the first substrate 1 by a length L, and the anode oxide 
electrode 5 is cut along the separation line 34 upon completion of the 
anodic oxidation treatment, so that the anode oxide electrode 5 and the 
cut portion 62 are separated from the first substrate 1. 
However, it is necessary to provide the cut portion 62 so as to separate 
the anode oxide electrode 5 from the signal electrode 4. Accordingly, the 
anode oxide electrode 5 requires such a sizes that it can be bent by 
fingers of an operator after the separation line 34 is perforated, which 
causes a problem of wasting material of the cut portion 62 involved in 
bending and cutting the cut portion 62. 
Further, in a step of separating the cut portion 62 from the signal 
electrode 4, there is a possibility that the nonlinear resistor 9 is 
deteriorated in characteristics by static electricity. 
Since the end surface of each signal electrode is exposed at the cut part 
of the first substrate 1, there is a possibility that a short circuit 
occurs between a plurality of signal electrodes owing to adhesion of dust 
and moisture. 
There is a possibility that the nonlinear resistor is deteriorated in 
characteristics and damaged depending on time when the cutting step of the 
anode oxide electrode 5 is taken. 
It is impossible to disperse static electricity which locally occurs when 
the anode oxide electrode 5 are separated from each other during the 
orientation process for aligning the liquid crystal regularly, which is a 
treatment for processing the first substrate 1 having the nonlinear 
resistor 9 to be used for the liquid crystal display device, and during 
the conveyance or inspection of the liquid crystal display device. 
Accordingly, there is a possibility that the nonlinear resistor 9 is 
deteriorated in characteristics or damaged when an excessive voltage is 
applied to the nonlinear resistor 9. 
Further, it is possible to prevent the nonlinear resistor 9 from being 
deteriorated in characteristics and damaged by connecting the anode oxide 
electrodes with each other during the inspection of the liquid crystal 
display device. 
Still further, it is possible to easily inspect the liquid crystal display 
device since the voltage can be applied to the display electrodes 7 by 
merely applying the voltage to the anode oxide electrodes 5 which are 
connected to each other during the inspection step of the liquid crystal 
display device. 
It is required that the contaminant material does not enter between 
mounting electrodes and a conductive paste before ICs are mounted on the 
substrate, particularly when the external circuit is mount(ed on the first 
substrate 1 forming the nonlinear resistor 9, for example, when the ICs, 
which can be mounted with high density, are mounted on the substrate using 
a conductive adhesive by a chip on glass (COG) mounting method. 
Accordingly, in a structure where the cut portion is defined in the first 
substrate 1 and the anode oxide electrode is formed on the cut portion, 
and the cut portion is cut upon completion of the anodic oxidation 
treatment to thereby separate the anode oxide electrode from the signal 
electrode as described above, the material is wasted and above-mentioned 
various demands cannot be satisfied. 
Consequently, it is a first object of the invention to provide a liquid 
crystal display device capable of easily removing a part of the anode 
oxide electrode by an etching treatment upon completion of the 
aforementioned various steps, so as to permit the signal electrodes to be 
independent of each other, thereby preventing the nonlinear resistor from 
being deteriorated in characteristics and damaged owing to static 
electricity which occurs during a fabricating step of the nonlinear 
resistor or during the succeeding steps for manufacturing the liquid 
crystal display device, and reducing defects of the nonlinear resistor so 
as to stabilize the characteristics of the nonlinear resistor. 
It is another object of the invention to dispense with a part such as a cut 
portion shown in FIG. 46, which is to be wasted, and to effectively 
utilize a part which remains after the signal electrodes for the anode 
oxide electrode used in the anodic oxidation treatment are separated from 
the anode oxide electrode. 
Further, the liquid crystal display device having the aforementioned 
conventional nonlinear resistors has signal electrodes made of a metal 
film, and the initial signal electrode and the final signal electrode are 
the same in wiring width thereof. Accordingly, there is a problem that the 
signal electrode is hard to repair if poor etching occurs at a part of the 
signal electrode. 
Further, in case that the signal electrode is used as a part of the anode 
oxide electrode, the anode oxide film cannot be formed if the signal 
electrode is broken. Still further, it is necessary to form the anode 
oxide electrode 5 as wide as possible so as to uniformly form an anode 
oxide film. 
Still further, when the transparent conductive film is used as the display 
electrode, a short circuited part between the signal electrode and the 
display electrode cannot be easily detected since the display electrode is 
transparent even if the signal electrode and the display electrode are 
electrically short circuited owing to poor etching of the transparent 
conductive film. 
Further, as for the TFT element, there is a possibility of occurrence of 
the breakage of the anode oxide electrode or an electric short circuit 
between the signal electrode (gate electrode or source electrode) and the 
transparent display electrode like the TFD element in case that anode 
oxide film of the gate electrode is used as the gate insulating film 
utilizing the gate electrode as the anode oxide electrode. 
Accordingly, it is still another object of the invention capable of surely 
and uniformly forming an anode oxide film serving as the nonlinear 
resistor layers of the nonlinear resistors using the signal electrode as a 
part of the anode oxide electrode, of easily repairing a poorly etched 
part when the poor etching occurs in a part of the signal electrode, and 
of easily detecting a short circuited part when there occurs an electric 
short circuit between the display electrode of the transparent conductive 
film and the signal electrode or the anode oxide electrode. 
SUMMARY OF THE INVENTION 
To achieve the above objects of the invention, a liquid crystal display 
device is structured as follows. 
The liquid crystal display device which is a subject of the invention 
includes a first substrate and a second substrate which confront each 
other at a certain gap, a plurality of electrodes disposed on the first 
substrate, a nonlinear resistor layer formed by an anode oxide film of one 
electrode in a region where the plurality of electrodes overlap, thereby 
forming nonlinear resistors such as a TFD element or TFT element. The 
liquid crystal display device has a structure further including a liquid 
crystal which is filled between the first substrate and the second 
substrate. 
The electrodes are independent of each other by providing the anode oxide 
electrode for performing the anodic oxidation treatment quickly and 
uniformly by connecting the electrodes forming the anode oxide film to 
each other in advance so as to form the nonlinear resistor layer and other 
electrodes for masking a part of the anode oxide electrodes, and removing 
exposed parts of the anode oxide electrodes by etching utilizing other 
electrodes as a mask upon completion of the anodic oxidation treatment. 
Accordingly, it is possible to omit or reduce a special covering for 
masking, and to perform an etching treatment so as to permit the 
electrodes to be easily independent of each other in an arbitrary step 
upon completion of the anodic oxidation treatment. 
Further, the remaining parts of the anode oxide electrode can be 
effectively utilized for a connecting electrode, an input electrode 
(terminal), and the like. 
Still further, when the anode oxide electrode is provided at the periphery 
of a display region or of a display element, it can be utilized as a 
shading portion, so that a frame can be provided in the liquid crystal 
display device having no black matrix. 
Still further, it is possible to improve uniformity of the anode oxide film 
and to enhance the prevention of breakage of the anode oxide film by 
permitting the width of the anode oxide electrode to be wide at the 
initial stage, so that the electrode can be repaired utilizing the widened 
part of the anode oxide electrode even if the electrode is partly 
defective.

BEST MODE FOR CARRYING OUT THE INVENTION 
Embodiments of the invention will be now described with reference to the 
attached drawings for explaining the content of the invention in more 
detail. 
In FIGS. 1 through 44 used for explaining the following embodiments, 
components corresponding to those as explained above in FIGS. 45 through 
47, and components corresponding to those(in figures of each embodiment 
are denoted by the same numerals. 
First Embodiment 
First of all, a structure of a liquid crystal display device(according to a 
first embodiment of the invention will be described with reference to 
FIGS. 1 and 2. 
FIG. 1 is a plan view showing a part of a liquid crystal display device 
according to the first embodiment of the invention, and FIG. 2 is a cross 
sectional view taken along the line A--A in FIG. 1. In FIG. 1, 
illustration of first and second substrates is omitted. 
The basic structure of the liquid crystal display device is the same as 
that of the aforementioned conventional liquid crystal display device, and 
it comprises the first and second substrates 1 and 11 made of a material 
such as a transparent glass and opposing each other at a certain gap by 
way of a spacer not shown, and the liquid crystal 16 is filled between the 
first and second substrates 1 and 11. 
The lower electrode 2 made of a tantalum (Ta) film, the signal electrode 4 
and the anode oxide electrode 5 are disposed on the first substrate 1 as a 
first electrode. A nonlinear resistor layer 3 made of a tantalum oxide 
(Ta.sub.2 O.sub.5) film which is an anode oxide film of the lower 
electrode 2 by itself is formed on the lower electrode 2. The anode oxide 
film is formed on an entire surface of the first electrode, namely, on the 
surfaces of the signal electrode 4 and the anode oxide electrode 5 as well 
as on the surface of the lower electrode 2. 
Further, an upper electrode 6 on the nonlinear resistor layer 3, a display 
electrode 7 connected to the upper electrode 6 and a connecting electrode 
8 forming a part of the anode oxide electrode 5 are made of an indium tin 
oxide (ITO) film as a second electrode. 
The lower electrode 2, the nonlinear resistor layer 3 and the upper 
electrode 6 constitute a TFD structured nonlinear resistor 9. 
The connecting electrode 8 comprising the second electrode covers a part of 
the anode oxide electrode 5 comprising the first electrode, wherein runner 
parts 5a of the anode oxide electrodes 5 connect the signal electrodes 4 
in each row with each other at the time of the anodic oxidation treatment 
as shown by imaginary lines in FIG. 1, and they are separated from each 
other at a separating side 10 of the connecting electrode 8 upon 
completion of the anodic oxidation treatment, thereby constituting 
independent signal electrodes 4. 
The connecting electrode 8 is an electrode to be connected to an output 
terminal 100a of a driver IC 100 for driving the liquid crystal display 
device as shown in FIG. 2. 
A black matrix 12 made of a chromium (Cr) film is disposed on an inner 
surface of the second substrate 11 for preventing leaking of light from 
gaps between the display electrodes 7 disposed on the first substrate 1. 
Incidentally, the black matrix 12 is not disposed on the second substrate 
11 at a region opposing the display electrode 7 disposed on the first 
substrate 1 as shown in FIG. 1. 
An opposed electrode 13 made of an indium tin oxide film is disposed on the 
inner surface of the second substrate 11 so as to oppose the display 
electrode 7. The opposed electrode 13 is provided by way of an interlayer 
insulating film 14 so as not to be short circuited when it contacts the 
black matrix 12. 
The first electrode (signal electrode 4) and the display electrode 7 are 
spaced at a certain gap so that they are not short circuited as shown in 
FIG. 1. 
The display electrode 7 becomes a display pixel portion of a liquid crystal 
display panel when it is arranged to overlap the opposed electrode 13 by 
way of the liquid crystal 16 as shown in FIG. 2. In each display pixel 
portion, the black matrix 12 has an opening 12a. A region for forming the 
black matrix 12 which is shown by the hatched line in FIG. 1 becomes a 
shading portion. 
Owing to the change of transmittance of the liquid crystal 16 in the 
display pixel portion, the liquid crystal display device performs a 
predetermined pixel display. 
Further, the first substrate 1 and the second substrate 11 respectively 
have orientational films 15 and 15 respectively as processing layers for 
regularly aligning molecules of the liquid crystal 16. 
With the arrangement of the first embodiment as explained above, the anode 
oxide electrode 5 comprising the first electrode has a structure that it 
is separated in a self-matching manner by the connecting electrode 8 
comprising the second electrode. 
That is, the signal electrodes 4 in each row are connected to each other by 
the anode oxide electrodes 5 when the anodic oxidation treatment is 
performed on the lower electrode 2 to form the nonlinear resistor layer. 
When an etching treatment is performed using the connecting electrode 8 
comprising the second electrode serving as a mask upon completion of the 
anodic oxidation treatment, e.g. upon completion of the inspection of the 
liquid crystal display panel, the runner parts 5a of the anode oxide 
electrodes 5 which are not covered with the connecting electrode 8 are 
removed, and they are separated from each other at the separating side 10 
of the connecting electrode 8, thereby constituting the independent signal 
electrodes 4 in each row. 
Since the connecting electrode 8 which is the second electrode is used as 
an etching mask, it is possible to process the signal electrodes 4, which 
are connected to each other, to form independent signal electrodes during 
manufacturing of or inspecting of the liquid crystal display panel or upon 
completion of the inspection of the liquid crystal display panel. 
Accordingly, it is possible to apply an external signal to nonlinear 
resistors 9 in each row using the signal electrodes 4 which are 
independent of the connecting electrodes 8. 
In such steps which involve generating static electricity as printing the 
orientational films 15 onto the first substrate 1 having the nonlinear 
resistor 9 or performing an orienting process by rubbing the surfaces of 
the orientational films 15 with a cloth, the signal electrodes 4 remain 
connected to each other by the anode oxide electrodes 5, thereby 
preventing the nonlinear resistor 9 from being deteriorated in 
characteristics. 
As a result, it is possible to obtain the liquid crystal display device 
having a uniform and stable characteristic and excellent display quality. 
Second Embodiment 
A structure of a liquid crystal display device according to a second 
embodiment of the invention will be described next with reference to FIGS. 
3 and 4. 
FIG. 3 is a plan view showing a part of the liquid crystal display device 
according to the second embodiment of the invention, and FIG. 4 is a cross 
sectional view taken along the line B--B in FIG. 3. First and second 
substrates are not shown in FIG. 3. 
Also in the second embodiment, the lower electrode 2, the signal electrode 
4 and the anode oxide electrode 5 are disposed on the first substrate 1 as 
a first electrode made of a tantalum (Ta) film. The nonlinear resistor 
layer 3 made of a tantalum oxide (Ta.sub.2 O.sub.5) film is formed on the 
surface of the first electrode including the lower electrode 2 as an anode 
oxide film of the first electrode by itself. 
Further, the upper electrode 6 made of a chromium (Cr) film and a first 
connecting electrode 22 forming a part of the anode oxide electrode made 
of the same chromium (Cr) film are formed on the nonlinear resistor layer 
3 as a second electrode. 
The lower electrode 2, the nonlinear resistor layer 3 and the upper 
electrode 6 constitute the TFD structured nonlinear resistor 9. 
The display electrode 7 and the second connecting electrode 8 
(corresponding to the connecting electrode 8 in the first embodiment) 
forming a part of the anode oxide electrode 5 are made of an indium tin 
oxide (ITO) film and disposed on the first substrate 1 as a third 
electrode. The upper electrode 6 is electrically connected to the display 
electrode 7 by way of a connecting part 7a forming the part of the display 
electrode 7. 
Further, the first connecting electrode 22 comprising the second electrode 
and the second connecting electrode 8 comprising the third electrode cover 
a part of the anode oxide electrodes 5 comprising the first electrode, 
wherein the anode oxide electrodes 5 are separated at the separating side 
10 of the second connecting electrode 8, thereby constituting independent 
connecting terminals 23, 24, 25 . . . . 
Since the connecting terminals 23, 24, 25 . . . conduct with the signal 
electrodes 4 in each row by way of the separated anode oxide electrodes 5, 
an external circuit (a driver IC, etc. like the case of the first 
embodiment) is connected to the connecting terminals 23, 24, 25 . . . so 
as to apply a voltage independently to the nonlinear resistors 9 by way of 
the signal electrodes 4 in each row, so that an intended image can be 
displayed on the display electrodes 7. 
Further, in the second embodiment, the connecting terminals 23, 24, 25 . . 
. are disposed on the terminal forming part 1a of the first substrate 1 to 
be close to each other so that they can be connected to the external 
circuit using a chip-on-glass (COG) method. 
The COG method comprises forming an anisotropic conductive sealing agent or 
conductive particles in convex on a semiconductor integrated circuit (IC) 
so as to mount the IC on the substrate utilizing an adhesive in the 
anisotropic conductive sealing agent. 
Also in the second embodiment, the signal electrodes 4 in each row are 
connected to each other by the anode oxide electrode 5 when the anodic 
oxidation treatment is performed for forming the nonlinear resistor layer 
on the lower electrode 2. 
Further, when the etching treatment is performed using the second 
connecting electrode 8 comprising the second electrode as a mask upon 
completion of the anodic oxidation treatment, e.g., upon completion of the 
inspection of the liquid crystal display panel, the runner parts 5a (shown 
by an imaginary line in FIG. 3) which are not covered with the second 
connecting electrode 8 of the anode oxide electrode 5 are removed, and 
they are separated from each other at each separating side 10 in the 
periphery of the second connecting electrode 8, thereby constituting the 
independent connecting terminals 23, 24, 25 . . . conducting the signal 
electrodes in each row. 
Consequently, according to the second embodiment, even in the case of 
utilizing the COG method which is employed for mounting of the ICs with 
high density, the signal electrodes 4 are connected to each other by the 
anode oxide electrode 5 at the time of anodic oxidation treatment, and 
thereafter they may be independent of each other with a simple etching 
treatment upon completion of predetermined steps. 
Accordingly, it is possible to obtain the same effect; as the first 
embodiment, and also possible to easily process each terminal of the 
independent signal electrodes even in case that the electrode terminals 
are arranged with high density, which is needed for mounting the ICs with 
high density during manufacturing of or inspecting of the liquid crystal 
display panel or upon completion of the inspection of the liquid crystal 
display panel. 
Further, it is possible to enhance the adhesive force or bonding between 
the anode oxide electrode 5 and the second connecting electrode 8 since 
the first connecting electrode 22 comprising the second electrode and the 
second connecting electrode 8 comprising the third electrode are formed in 
this order on the anode oxide electrode 5 comprising the first electrode. 
Third Embodiment 
A liquid crystal display device according to a third Embodiment of the 
invention will be described next with reference to FIGS. 5 through 8. 
FIG. 5 is a plan view showing a state where a plurality of substrates for 
liquid crystal display devices are arranged on a large substrate according 
to a third embodiment of the invention. FIG. 6 is an enlarged plan view 
showing a bordering part of two substrates of the liquid crystal display 
devices which are encircled by a broken line in FIG. 5. FIG. 7 is a cross 
sectional view taken along the line C--C in FIG. 6, and FIG. 8 is a cross 
sectional view taken along the line D--D in FIG. 6. 
As shown in the plan view in FIG. 5, a plurality of (6 in this case) 
substrates 31, 32 . . . for the liquid crystal display devices are formed 
on a first large substrate 30. The substrates 31 and 32 . . . for the 
liquid crystal display devices are used by being separated at separating 
lines 33 and 34. 
Further, as the first electrode made of the tantalum (Ta) film, the lower 
electrode 2, the signal electrode 4 and an anode oxide electrode 41 are 
disposed on the substrates 31 or 32 for the liquid crystal display devices 
(corresponding to the first substrate 1 of the aforementioned embodiments) 
as shown in FIGS. 6 and 8. 
The anode oxide electrode 41 has a structure that it is disposed on the 
substrate 32 for the liquid crystal display device as shown in FIG. 6, and 
it connects the signal electrodes 4 of the adjoining substrates 31 for the 
liquid crystal display devices to each other to apply a voltage from the 
signal electrodes 4 to the lower electrodes 2 at the time of anodic 
oxidation treatment. 
There is provided on the lower electrode 2 the nonlinear resistor layer 3 
made of the tantalum oxide (Ta.sub.2 O.sub.5) film serving as an anode 
oxide film formed by subjecting the lower electrode 2 by itself to an 
anodic oxidation treatment. 
Further, the upper electrode 6 provided on the nonlinear resistor layer 3, 
the display electrode 7 connected to the upper electrode 6, and an input 
electrode 8' (corresponding to the connecting electrode 8 in the 
aforementioned embodiments) for covering a part of the anode oxide 
electrode 41 comprising the first electrode on the adjoining substrates 
for the liquid crystal display devices disposed on the large substrate 30 
are provided as the second electrode made of an indium tin oxide (ITO) 
film. 
The lower electrode 2, the nonlinear resistor layer 3 and the upper 
electrode 6 constitute the TFD structured nonlinear resistor 9. 
As shown in FIG. 6, since the input electrode 8' comprising the second 
electrode covers a part of the anode oxide electrode 41 comprising the 
first electrode of the adjoining substrates 32 for the liquid crystal 
display devices, the anode oxide electrode 41 is separated at the side 
which is the same as that of the input electrode 8' in the etching 
treatment upon completion of the anodic oxidation treatment, so that the 
parts as illustrated by imaginary lines shown in FIG. 6 are removed. 
Accordingly, independent input terminals 38, 39 and 40 in the adjoining 
substrates 32 for the liquid crystal display devices are formed together 
with the connecting terminals 23, 24, 25, and 26 for the driver ICs. 
Denoted by 60 is a seal for sealing the liquid crystal 16 between the 
substrate 31 or 32 for the liquid crystal display device and the second 
substrate 11, and the internal structure thereof as the liquid crystal 
display device is the same as that of the first embodiment. 
With the arrangement of the third embodiment, even if the substrates for 
the liquid crystal display devices are disposed in plural numbers on the 
large substrate, the signal electrodes 4 are connected to each other by 
the anode oxide electrode 41 at the time of anodic oxidation treatment, 
and it is possible to obtain independent signal electrodes 4 as the anode 
oxide electrode 41 when performing the etching treatment using the input 
electrode 8' as a mask during or after the inspection of the liquid 
crystal display panel. 
Accordingly, the independent signal electrodes can be easily processed even 
if the high density signal electrodes necessary for mounting the ICs with 
high density are arranged. 
In the case of providing a plurality of substrates for the liquid crystal 
display devices on the large substrate, the connection and separation of 
signal electrodes 4 are carried out utilizing the anode oxide electrode 41 
comprising the first electrode of the adjoining liquid crystal display 
devices and the input electrode 8' comprising the second electrode thereof 
so that a space for removing the anode oxide electrode is not required, 
enabling an effective utilization of the large substrate. 
Parts which remain after the anode oxide films 41 or 5 are separated can be 
effectively utilized as input terminals or connecting terminals of the 
adjoining liquid crystal display device. 
Fourth Embodiment 
A liquid crystal display device according to a fourth embodiment of the 
invention will be described next with reference to FIGS. 9 and 10. 
FIG. 9 is a plan view showing a part of a first substrate of the liquid 
crystal display device according to the fourth embodiment of the 
invention, and FIG. 10 is a cross sectional view taken along the line E--E 
in FIG. 9 in a state where the liquid crystal display device is 
structured. 
The lower electrode 2 made of a tantalum (Ta) film, a signal electrode 50, 
a first anode oxide electrode 55 and a second anode oxide electrode 56 are 
disposed on the first substrate 1 as a first electrode in the present 
embodiment. 
Further, the nonlinear resistor layer 3 made of a tantalum oxide (Ta.sub.2 
O.sub.5) film which is the anode oxide film of the lower electrode 2 by 
itself is provided on the lower electrode 2. The nonlinear resistor layer 
3 comprising the anode oxide film is also formed on the surfaces of the 
signal electrodes, the first anode oxide electrode 55 and the second anode 
oxide electrode 56 which are the first electrode the same as the lower 
electrode 2. 
The upper electrode 6 formed on the nonlinear resistor layer 3 and the 
display electrode 7 connected to the upper electrode 6 are respectively 
made of an indium oxide (ITO) film as the second electrode, and signal 
electrodes 50 extending onto the first substrate 1 outside the seal 60, 
the connecting electrodes 51, 52, 53 and 54 for covering a part of the 
first anode oxide electrode 55 between the signal electrodes 50, and a 
peripheral electrode 58 covering most of the second anode oxide electrodes 
56 are provided as the second electrode made of tantalum oxide. 
The second anode oxide electrode 56 and the peripheral electrode 58 are 
arranged so as to surround the connecting electrodes 51, 52, 53 and 54, 
and they are further connected to the peripheral electrode 57 which is 
adjacent to the display electrode 7 close to the seal 60. 
The lower electrode 2, the nonlinear resistor layer 3 and the upper 
electrode 6 constitute the TFD structured nonlinear resistor 9. 
There is a possibility that ion components of an orientational film 15 to 
regularly align liquid crystals or the liquid crystal 16 influence upon 
the nonlinear resistor 9 so that the nonlinear resistor 9 is, changed or 
deteriorated in characteristics. 
A transparent insulating film 48 is provided on the nonlinear resistor 9 or 
on the periphery thereof so as to prevent the nonlinear resistor 9 from 
being changed or deteriorated in characteristics. 
The insulating film 48 has an opening 49 at the upper part of the first 
anode oxide electrode 55 for connecting the connecting electrodes 51 
through 54 of the signal electrodes 50 and the second anode oxide 
electrode 56. 
In a state where the liquid crystal display device is structured, a part of 
the first anode oxide electrode 55 exposed to the opening of the 
insulating film 48 as illustrated by imaginary lines in FIG. 9 is removed. 
Accordingly, the connecting electrodes 51 through 54 and the peripheral 
electrode 58 are electrically separated from each other, thereby 
constituting the independent electrodes. 
Other structures are the same as those of the aforementioned embodiments. 
In the structure of the liquid crystal display device according to the 
fourth embodiment, the insulating film 48 is provided on the anode oxide 
electrodes 55 and 56 comprising the first electrode for preventing the 
nonlinear resistor 9 from being changed or deteriorated in characteristic. 
In the opening 49 of the insulating film 48, the anode oxide electrode 55 
comprising the first electrode has such a shape that it is separated at a 
part of the side of the second electrode while it is self-aligned so that 
the signal electrodes 50 are independent of each other, and the connecting 
electrodes 51 through 54 constitute independent electrode terminals 
connected to an external circuit such as the driver IC 100 as illustrated 
by an imaginary line in FIG. 10. 
When the anodic oxidation treatment is performed in this embodiment, it is 
possible to obtain the same effect as that of the aforementioned 
embodiments since the signal electrodes 50 are connected to each other by 
the first and second anode oxide electrodes 55 and 56. 
Since the second anode oxide electrodes 56 are arranged close to the 
connecting electrodes 51 through 54, and the connecting electrodes 51 
through 54 are connected to each other by branched portions of the first 
anode oxide electrodes 55, it is possible to disperse the static 
electricity to the peripheries of the connecting electrodes 51 through 54 
and the signal electrode 50 when the static electricity is generated in 
the connecting electrodes 51 through 54 or from the signal electrode 50. 
Further, there is no increase in manufacturing steps since the first anode 
oxide electrode 55 in the opening 49 (illustrated by the imaginary lines 
in FIG. 9) is removed so as to process the signal electrodes 50 to be 
independent of each other at the same time when performing the etching 
treatment when the opening 49 is defined in the insulating film 48. 
The second substrate 11 and the seal 60 are assembled with each other when 
the opening 49 is defined in the insulating film 48. 
By this, it is possible to define the opening 49 in the insulating film 48 
when a voltage is applied from a region where a part of the insulating 
film is removed by laser beam to the signal electrode 50 upon completion 
of the manufacture or inspection of the liquid crystal display panel which 
is liable to generate static electricity or immediately before the driver 
IC 100 is mounted using the chip-on-glass method. 
Accordingly, it is possible to prevent the nonlinear resistor 9 from being 
deteriorated in characteristic in the step involving in generation of 
static electricity such as the step of printing the orientational films 15 
onto the first substrate 1 having the nonlinear resistor 9 or the step of 
performing orienting process by rubbing the surfaces of the orientational 
films 15 with a cloth. 
As a result, it is possible to obtain a liquid crystal display device 
having uniform and stable characteristics with excellent display quality. 
Modifications of First to Fourth Embodiments 
A tantalum film is employed as the first electrode in the first to fourth 
embodiments. Besides, it is possible to employ a tantalum film containing 
nitrogen, a tantalum film containing phosphorus, or a tantalum film 
containing niobium as well as an ordinary tantalum film as a first 
electrode. 
Further, it is possible to employ a multilayer film as the first electrode 
comprising a low resistance material such as aluminum, copper or nickel, 
and a film comprising tantalum or tantalum containing impurities. 
In each of the aforementioned embodiments, a tantalum film is employed as 
the first electrodes 2 and the tantalum oxide film is formed as the 
nonlinear resistor layer. However, it may be possible to provide a silicon 
oxide film, a silicon nitride film or silicon oxides containing impurities 
on the surface of the tantalum oxide film, and to employ a nonlinear 
resistor layer comprising a multilayer film composed of the tantalum oxide 
film and these films. 
Further, a film to be formed on the tantalum oxide film of the nonlinear 
resistor layer comprising the multilayer film is preferable to be formed 
utilizing a plasma vapor chemical deposition method (CVD method). Thus, 
when a voltage is applied to the tantalum oxide film, electrical stability 
is improved, thereby preventing the nonlinear resistor from being 
deteriorated. 
Further, it is possible to control a current-voltage characteristic of the 
nonlinear resistor by employment of the nonlinear resistor layer 
comprising the multilayer film. Accordingly, an overcurrent is restrained 
from flowing to the nonlinear resistor, thereby further improving the 
characteristics of the liquid crystal display device. 
Still further, although the liquid crystal display device has one nonlinear 
resistor in each pixel in the first to fourth embodiments, a plurality of 
nonlinear resistors may also be provided in each pixel. 
Even in this case, it is possible to control the current-voltage 
characteristic of the nonlinear resistor by employment of a nonlinear 
resistor layer comprising a multiple layer film. As a result, the 
overcurrent is restrained from flowing into the nonlinear resistor, 
thereby improving the characteristics of the liquid crystal display 
device. 
Fifth Embodiment 
A liquid crystal display device according to a fifth embodiment of the 
invention will be described next with reference to FIGS. 11 through 14. 
FIG. 11 is a plan view showing an entire structure of the liquid crystal 
display device according to the fifth embodiment, and the structures of 
both first and second substrates which are overlaid on top of each other 
are denoted by solid lines so as to be understood easily. 
FIG. 12 is a plan view enlarging the parts encircled by the broken lines a 
and b in FIG. 11. The upper substrate and a film formed thereon are not 
shown in FIG. 12. The part encircled by the broken line a is shown above 
while the part encircled by the broken line b is shown below. 
FIG. 13 is a cross sectional view taken alone the line F--F in FIG. 12 in a 
state where the liquid crystal display device is structured, and FIG. 14 
is a cross sectional view taken along the line G--G in the same FIG. 12. 
The basic structure of the liquid crystal display device of this embodiment 
is common to that of the aforementioned each embodiment. 
That is, the lower electrode 2, the signal electrode 4 and the anode oxide 
electrode 5 are provided on the first substrate 1 as the first electrode 
comprising the tantalum (Ta) film. The nonlinear resistor layer 3 made of 
a tantalum oxide (Ta.sub.2 O.sub.5) film is formed on the lower electrode 
2 and the anode oxide electrode 5 as the anode oxide film of these first 
electrodes. 
In this embodiment, the anode oxide electrode 5 is formed in a belt shape 
so as to surround the periphery of the display region 18 as illustrated by 
a hatched line in FIG. 11. A mutual connecting electrode 65 is provided at 
the end of the first substrate 1 to connect the anode oxide electrodes 5 
of the first substrates 1 to prepare a plurality of first substrates 1 
from a large basic substrate. 
The anode oxide electrodes 5 comprising the first electrode has a structure 
that a plurality of signal electrodes 4, 4 . . . are connected to each 
other at a periphery of the matrix-shaped display region 18 comprising the 
signal electrodes 4 in M rows and the opposed electrodes 13 in N columns 
as shown in FIGS. 11 and 12. 
The upper electrode 6 on the nonlinear resistor layer 3 and the display 
electrode 7 connected to the upper electrode 6 are made of an indium tin 
oxide (ITO) film as the second electrode. 
The lower electrode 2, the nonlinear resistor layer 3 and the upper 
electrode 6 constitute the TFD structured nonlinear resistor 9. 
Further, the peripheral electrodes 57 illustrated by a hatched line, 
connecting electrodes 71 through 74 connected to signal electrodes 4 and 
extending to a terminal forming part 1a outside the seal 60 of the first 
substrate 1, rectangular shading electrodes 75 which are arranged between 
the connecting electrodes with slight gaps, and the peripheral electrode 
58 extending from the peripheral electrode 57 so as to surround the tip 
ends of the connecting electrodes 71 through 74 are made of an indium tin 
oxide (ITO) film as the second electrodes and are arranged on the anode 
oxide electrodes 5 provided so as to surround the display region 18 in 
which a plurality of display electrodes 7 are arranged in a matrix shape 
in FIG. 12. 
That is, all of the anode oxide electrodes 5 are formed at the lower parts 
of each electrode illustrated by the hatched lines in FIG. 12, and all of 
the signal electrodes 4 are surely connected to each other at both ends 
thereof by the anode oxide electrodes 5 at the time of the anodic 
oxidation treatment. 
The peripheral electrodes 57 and 58, the connecting electrodes 71 through 
74 and the shading electrodes 75 comprising these second electrodes serve 
as a mask to cover a part of the anode oxide electrodes 5, wherein the 
display region 18 in a width denoted by D in FIG. 12 is subject to an 
etching treatment while it is masked, so that the part of the anode oxide 
electrodes 5 exposed through these masks are removed. 
Accordingly, the signal electrodes 4 and the connecting electrodes 71 
through 74 connected thereto are separated from each other, thereby 
constituting the independent electrodes. 
In FIGS. 13 and 14, the removed parts of the anode oxide electrodes 5 and 
the nonlinear resistor layers 3 are illustrated by imaginary lines. 
The other structures are the same as those of the aforementioned 
embodiments, and hence the explanation thereof is omitted. 
Also in the fifth embodiment, since the signal electrodes 4 are connected 
to each other by the anode oxide electrodes 5 at the time of anodic 
oxidation treatment for forming the nonlinear resistor layer 3 and in the 
succeeding inspection step, etc., the same effect as that of the 
aforementioned embodiments can be obtained. Further, since the connection 
of the signal electrodes 4 is carried out at both ends thereof, it can be 
surely performed, and even if the signal electrodes are broken at some 
part of the signal electrodes, the anodic oxidation treatment can be 
surely performed. 
When the etching treatment is performed in an arbitrary step utilizing the 
second electrode as a mask, it is possible to easily separate the signal 
electrodes 4 from the connecting electrodes 71 through 74 in FIG. 12, 
thereby forming the independent electrodes. At this time, both sides of 
the peripheral electrode 57, right and left sides of the connecting 
electrodes 71 through 74 and the peripheral sides of the shading 
electrodes 75 form the separating side. 
Opaque anode oxide electrodes 5 remain on the outer periphery of the 
display region 18 to form the shading portion, thereby (constituting a 
frame of the display region 18. 
In such a manner, it is possible to form the frame (frame surrounding the 
periphery of the display region) even in the liquid crystal display device 
having no black matrix 12 by utilizing the anode oxide electrode 5 as the 
shading portion. 
The width of the anode oxide electrode 5 can be widened by the anode oxide 
electrode 5 which is utilized for the frame, thereby improving uniformity 
of the anode oxide film. 
Sixth Embodiment 
A liquid crystal display device according to a sixth (embodiment of the 
invention will be described next with reference to FIGS. 15 and 16. 
In the sixth embodiment, TFD structured elements are employed as the 
nonlinear resistor in which two TFD elements are connected in series with 
each other in each pixel portion, and the TFD elements are provided at the 
data electrodes arranged in N columns. 
FIG. 15 is a plan view enlarging a part of the liquid crystal display 
device, and FIG. 16 is a cross sectional view taken along the line H--H of 
FIG. 15. 
In this embodiment, an island-shaped lower electrode 2, a first data 
electrode 82, the anode oxide electrode 5, a line connecting part 76 for 
connecting the island-shaped lower electrode 2 and the first data 
electrode 82 are disposed on the first substrate 1 as a first electrode 
made of a tantalum (Ta) film, and the nonlinear resistor layer 3 made of a 
tantalum oxide (Ta.sub.2 O.sub.5) film is formed on the first electrode as 
the anode oxide film of the first electrode. 
The anode oxide electrode 5 comprising the first electrode has a structure 
that it connects a plurality of data electrodes 81 and 81 to each other at 
the periphery of the matrix-shaped display region comprising the opposite 
electrodes in M rows and the data electrodes 81, 81 in N columns. 
Further, an upper electrode 84 for a data electrode to be connected to a 
second data electrode 83, an upper electrode 85 for a display electrode to 
be connected to the display electrode 7, the display electrode 7 and the 
second data electrode 83 on the first data electrode 82, which are made of 
an indium tin oxide (ITO) film are disposed on the nonlinear resistor 3 on 
the island-shaped lower electrode 2 as the second electrode. 
The island-shaped lower electrode 2, the nonlinear resistor layer 3 and the 
upper electrode 84 for a data electrode constitute a TFD structured first 
nonlinear resistor 86. Further, the island-shaped lower electrode 2, the 
nonlinear resistor layer 3 and the upper electrode 85 for a display 
electrode constitute a TFD structured second nonlinear resistor 87. 
The second data electrode 83, the upper electrode 84 for a data electrode, 
the nonlinear resistor layer 3, the lower electrode 2, the nonlinear 
resistor layer 3, the upper electrode 85 for a display electrode, and the 
display electrodes 7 are connected in this order. The second data 
electrode 83 and the display electrode 7 constitute symmetric TFD elements 
with respect to the island-shaped lower electrode 2. 
The insulating film 48 made of a tantalum oxide (Ta.sub.2 O.sub.5) film is 
provided on the first substrate 1 as shown in FIG. 16. A separating 
opening 91 for a wire connection part is defined in the insulating film 48 
at the periphery of the line connecting part 76 for connecting the first 
signal electrode 4 and the island-shaped lower electrode 2. A plurality of 
separating openings 92 are defined in the anode oxide electrodes 5 as 
shown in FIG. 15. 
Further, a connecting opening 93 for connecting the external circuit and 
the second data electrode 83 is defined in the second data electrode 83. 
In the separating opening 91 for a wire connection part defined in the line 
connecting part 76 for connecting the first data electrode 82 and the 
island-shaped lower electrode 2, the insulating film 48 and the lower 
electrode 2 as the first electrode have the same separating side. 
In a plurality of the separating openings 92 defined in the anode oxide 
electrodes 5, the insulating film 48 and the anode oxide electrode 5 have 
the same separating side 10. 
The shading portions 70 formed by separating the anode oxide electrodes 5 
at the same separating side as the insulating, film 48 are provided on the 
upper and lower sides, and right and left sides of the display region. 
Accordingly, a frame is structured by the shading portion 70 at the outer 
periphery of the display region. 
Further, color filters comprising a red filter 95, a blue filter 96, and a 
green filter not shown, are provided at the inner surface of the second 
substrate 11 so that the liquid crystal display device performs a color 
display as shown in FIG. 16. A region 97 formed by overlapping the color 
filters is provided for preventing leaking of light from the gaps of the 
display electrodes 7. 
Further, the opposed electrode 13 made of the indium tin oxide film is 
disposed on the second substrate 11 so as to confront the display 
electrode 7. 
The display electrode 7 forms a display pixel portion of the liquid crystal 
display panel when it is disposed to overlap the opposed electrode 13 by 
way of the liquid crystal 16. The display pixel portion has a single color 
filter, e.g., the red filter 95. 
The liquid crystal display device performs a given image display owing to 
the change of transmittance of the liquid crystal 16 in the display pixel 
portion. 
Further, the orientational films 15 and 15 are provided between the first 
substrate 1 and the second substrate 11 as the processing layers for 
regularly aligning the molecules of the liquid crystal 16. 
With the arrangement of the sixth embodiment, the anode oxide electrodes 5 
comprising the first electrodes have the separating side 10 at which they 
are separated in a self-alignment manner by the opening of the insulating 
film 48 at the periphery of the display region. 
Further, as shown in this embodiment, when a plurality of TFD elements are 
connected with each other, it is necessary to separate the island-shaped 
lower electrodes 2 from the anode oxide electrode 5 or the first data 
electrode 82 after the nonlinear resistor layer 3 is formed. 
Accordingly, it is necessary to adopt a method of separating utilizing the 
opening of the insulating film 48 or separating without the insulating 
film. Owing to the presence of this separating step, the shading portion 
70 can be provided at the periphery of the display region using the anode 
oxide electrode 5 without particularly increasing the number of the steps 
in case of this embodiment. 
Accordingly, when the portion where the color filters overlap is used as 
the frame instead of the black matrix, a frame having a sufficient shading 
ability can be formed utilizing the shading portion 70 where the anode 
oxide electrode 5 remains even if the shading property is insufficient at 
the frame. 
Since a voltage can be applied from the periphery before the anode oxide 
electrode 5 is separated when the anodic oxidation treatment is performed 
for forming the nonlinear resistor layer 3, for example, even if there 
occurs a defect in a minority of the anode oxide electrodes 5, a voltage 
can be supplied from the other parts. 
Seventh Embodiment 
A liquid crystal display device according to a seventh embodiment of the 
invention will be described next with reference to FIGS. 17 and 18. 
In this embodiment, a TFT structured element is employed as the nonlinear 
resistor. 
FIG. 17 is a plan view enlarging a part of the liquid crystal display 
device, and FIG. 18 is a cross sectional view taken along the line I--I in 
FIG. 17. 
In this seventh embodiment, a gate electrode 101 corresponding to the 
signal electrode 4 and the anode oxide electrode are disposed on the first 
substrate 1 as the first electrode made of a tantalum (Ta) film, and a 
gate insulating film 102 made of a tantalum oxide (Ta.sub.2 O.sub.5) film 
is formed on the first electrode as the anode oxide film of the first 
electrode. 
The anode oxide electrodes 5 comprising the first electrode connects a 
plurality of gate electrodes 101 and 101 with each other at the periphery 
of the matrix-shaped display region comprising the gate electrodes 101 in 
M rows and a source electrode 105 in N columns as shown in FIG. 17. The 
anode oxide electrodes 5 are also provided under the peripheral electrode 
57 and the shading electrode 75, as shown by hatched lines in FIG. 17. 
An amorphous silicon (a-Si) film is provided on a gate insulating film 102 
and a periphery thereof as a semiconductor layer 103. Further, a 
semiconductor layer 104 containing phosphorus (P) as impurity ion is 
provided on the semiconductor layer 103. 
The source electrode 105 and a drain electrode 106 are provided on the 
semiconductor layer 104 containing impurity ions. The source electrode 105 
and the drain electrode 106 are made of molybdenum (Mo). The semiconductor 
layer 104 containing impurity ions is provided on an overlapping part 
where the source electrode 105, the drain electrode 106, and the 
semiconductor layer 103 overlap. Further, the source electrode 105 is 
connected to data electrodes 121 and 122 connected to the external 
circuit. 
The drain electrode 106 is connected to the display electrode 7 made of a 
transparent conductive film, thereby forming a display pixel portion. 
A film which is the same as the display electrode 7 is provided on the 
anode oxide electrode 5 connected to the gate electrode 101. A part of the 
anode oxide electrode 5 is separated at the separating side which is the 
same as that of the display electrode 7, forming the shading portion. 
A part of the anode oxide electrode 5 is covered with the peripheral 
electrode 57 and the anode shading electrodes 75 made of the films which 
are the same as that of the display electrode 7, wherein the display 
region is subject to an etching treatment while masking the display region 
so that the anode oxide electrodes 5 as shown by broken lines are removed, 
thereby permitting the gate electrodes 101 to be independent of each 
other. The frame is formed by the shading portion which is formed by the 
remained anode oxide electrode 5 at the outer peripheral portion of the 
display region. 
The opposed electrode 13 made of a transparent conductive film is first 
disposed on the second substrate 11 so as to reduce the amount of light of 
a reflecting light 112 from an external light source 111 as shown in FIG. 
18. Next, the black matrix 12 made of a chromium (Cr) film is provided for 
preventing leaking of light from the periphery of the display electrode 7. 
The reflecting light 112 can be reduced owing to the interference between 
the opposed electrode 13 made of the transparent conductive film, the 
second substrate 11 and the black matrix 12 made of the chromium film. 
The liquid crystal display device performs a given image display owing to 
the change of transmittance of the liquid crystal 16 of the display pixel 
portion. 
Further, the first substrate 1 and the second substrate 11 have 
orientational films 15 and 15 as processing layers for regularly aligning 
molecules of the liquid crystal 16. 
The first substrate 1 and the second substrate 11 are confronted each other 
at a certain gap by a spacer (not shown), and they are bonded to each 
other by the seal 60, thereby filling the liquid crystal 16 between the 
first substrate 1 and the second substrate 11. 
With the arrangement of the seventh embodiment, the anode oxide electrode 5 
comprising the first electrode has a separating side for separating in 
self-matching manner by the same film as the display electrode 7 at the 
periphery of the display region. 
It is possible to provide the shading portion at the periphery of the 
display region utilizing the anode oxide electrode 5 which remains after 
the separation thereof. 
Since a voltage can be applied from the periphery of the anode oxide 
electrode 5 to the gate electrode 101 when performing the anodic oxidation 
treatment for forming the nonlinear resistor layer, before the anode oxide 
electrodes 5 are separated, it is possible to apply a voltage from the 
other part even if there occurs a defect in a minority of the anode oxide 
electrodes 5. 
Eighth Embodiment 
A liquid crystal display device according to an eighth embodiment of the 
invention will be described next with reference to FIGS. 19 through 21. 
In the eighth embodiment, a TFD element is provided on the signal 
electrodes in M columns utilizing the TFD structured element as the 
nonlinear resistor. 
The shading portion provided at the periphery of the display electrode 7 
utilizes a part of a second anode oxide electrode 126, and a nonlinear 
resistor layer 128 on the second anode oxide electrode 126 is different in 
film thickness from the first nonlinear resistor layer 3 which is employed 
by the nonlinear resistor 9. 
FIG. 19 is a plan view showing an entire structure of the liquid crystal 
display device according to the eighth embodiment of the invention. FIG. 
20 is a plan view enlarging a part of the liquid crystal display device in 
FIG. 19, and FIG. 21 is a cross-sectional view taken along the line J--J 
in FIG. 21. However, FIGS. 20 and 21 omit the illustration of the upper 
second substrate, and films formed on the same substrate, etc., and the 
liquid crystal. 
The lower electrode 2, the signal electrode 4, the first anode oxide 
electrode 5, a second anode oxide electrode 126, an auxiliary electrode 
127 and a mutual connecting electrode 66 are disposed on the first 
substrate 1 as the first electrode made of a tantalum (Ta) film, and the 
first nonlinear resistor layer 3 made of a tantalum oxide (Ta.sub.2 
O.sub.5) film is provided on the lower electrode 2, the first anode oxide 
electrode 5 and the signal electrode 4 as the anode oxide film of the 
first electrode. 
The mutual connecting electrodes 65 are disposed on the ends of the first 
substrate 1 so as to connect the anode oxide electrodes 5 to each other 
for manufacturing a plurality of first substrates 1 from a large substrate 
as shown in FIG. 19. 
The nonlinear resistor layer 128 made of the tantalum (Ta.sub.2 O.sub.5) 
film is provided on the second anode oxide electrode 126 and the auxiliary 
electrode 127 as the anode oxide film of the first electrode. Further, the 
mutual connecting electrodes 65 and 65 are disposed on both ends of the 
first substrate 1 so as to connect the first anode oxide electrode 5 and 
the second anode oxide electrode 126 mutually for manufacturing a 
plurality of first substrates 1 from a large substrate as shown in FIG. 
19. 
The first anode oxide electrode 5 and the second anode oxide electrode 126 
are separated from each other. The second nonlinear resistor layer 128 is 
larger in film thickness than the first nonlinear resistor layer 3 which 
is employed by the nonlinear resistor 9. 
The first anode oxide electrode 5 comprising the first electrode has a 
structure that it connects a plurality of signal electrodes 4 to each 
other at the periphery of a matrix-shaped display region 18 composed of 
the signal electrodes 4 in M rows and the opposed electrode 13 in N 
columns. 
The second anode oxide electrode 126 has a structure that it connects a 
plurality of the auxiliary electrodes 127 by the mutual connecting 
electrode 66. Further, the upper electrode 6 provided on the first 
nonlinear resistor layer 3, the display electrode 7 connected to the upper 
electrode 6, and the connecting electrode 8 forming a part of the first 
anode oxide electrode 5 are made of indium tin oxide (ITO) film. 
The lower electrode 2, the first nonlinear resistor layer 3 and the upper 
electrode 6 constitute the TFD structured nonlinear resistor 9. 
A part of the display electrode 7 covers the auxiliary electrode 127 
connected to the second anode oxide electrode 126, and the display 
electrode 7 and the auxiliary electrode 127 constitute the shading 
portion. 
The insulating film 48 made of tantalum oxide (Ta.sub.2 O.sub.5) film is 
provided on the first substrate 1, the nonlinear resistor 9, the signal 
electrode 4, the display electrode 7, the first anode oxide electrode 5, 
and the second anode oxide electrode 126. 
The separating openings 92 are defined in the insulating film 48 and 
arranged on the first anode oxide electrode 5 and the second anode oxide 
electrode. The first anode oxide electrodes 5 are separated from each 
other at the separating side 10 which is the same as that of the 
separating openings 92, so that they constitute the independent signal 
electrodes 4, while the second anode oxide electrodes 126 constitute the 
independent auxiliary electrodes 127. 
Openings 49 are defined at the periphery of the display electrodes 7 and 
the auxiliary electrodes 127 are separated from each other at the 
separating side 10 which is the same as that of the display electrodes 7 
or the openings 49 of the insulating films 48 every display electrodes 7, 
thereby forming the shading portions. 
Openings 93 are also defined in the connecting electrode 8, enabled to be 
connected to the external circuit. 
The structure of the second substrate 11 is the same as those of the 
aforementioned embodiments, wherein it comprises a black matrix made of a 
chromium (Cr) film for preventing leaking of light from gaps between the 
display electrodes 7, the opposed electrode 13 and an interlayer 
insulating film for securing an electric insulation between the black 
matrix and the opposed electrode 13. 
The first substrate 1 and the second substrate 11 are bonded to each other 
at a certain gap, and the liquid crystal is filled therebetween, thereby 
forming the liquid crystal display device. 
With the arrangement of the eighth embodiment, the second anode oxide 
electrode 126 comprising the first electrode is independent of the anode 
oxide electrode 5 from the first stage. Accordingly, the influence of the 
second anode oxide electrode 126 is not given to the first anode oxide 
electrode 5. Further, the second anode oxide electrode 126 has the 
separating side 10 at which it is separated in self-matching manner from 
the display electrode 7 comprising the second electrode or the opening 49 
of the insulating film 48 at the periphery of the display region, thereby 
forming the independent shading portion for every display electrodes 7. 
Further, the second nonlinear resistor layer 128 provided on the second 
anode oxide electrode 126 is made larger in film thickness than the first 
nonlinear resistor layer 3 provided on the lower electrode 2 by the first 
anode oxide electrode 5, thereby enhancing insulating property, so that 
the yield is improved without influencing upon the display quality even if 
the display electrode 7 and the auxiliary electrode 127 are electrically 
short circuited. 
Ninth Embodiment 
A liquid crystal display device according to a ninth embodiment will be 
described next with reference to FIGS. 22 and 23. 
FIG. 22 is a plan view enlarging a part of the liquid crystal display 
device, and FIG. 23 is a cross sectional view taken along the line K--K in 
FIG. 22. In these figures, the components corresponding to those in FIGS. 
15 and 16 are denoted by the same numerals. 
The lower electrode 2, the first data electrode 82, a line connecting part 
76 for connecting the first data electrode 82 and the lower electrode 2, 
the first anode oxide electrode 5, the second anode oxide electrode 126, 
the auxiliary electrode 127, and the mutual connecting electrode 66 are 
disposed on the first substrate 1 as the first electrode made of tantalum 
(Ta) film according to this embodiment. 
The first nonlinear resistor layer 3 made of the tantalum oxide (Ta.sub.2 
O.sub.5) film is formed on the lower electrode 2, the first anode oxide 
electrode 5 and the first data electrode 82 as the anode oxide film of the 
first electrode. 
The second nonlinear resistor layer 128 made of the tantalum oxide 
(Ta.sub.2 O.sub.5) film is formed on the second anode oxide electrode 126 
and the auxiliary electrode 127 as the anode oxide film of the first 
electrode. 
The first anode oxide electrode 5 and the second anode oxide electrode 126 
are separated from each other. The second nonlinear resistor layer 128 is 
larger in film thickness than the first nonlinear resistor layer 3 which 
is employed by the nonlinear resistor 9. 
The first anode oxide electrode 5 comprising the first electrode has a 
structure that it connects the first data electrodes 81 in N columns to 
each other at the periphery of the display region as shown in FIG. 22. 
Further, the second anode oxide electrode 126 has a structure that it 
connects a plurality of auxiliary electrode 127 to each other. 
Further, as the second electrode, there are provided the second data 
electrode 83 on the first data electrode 82, the upper electrode 84 for a 
data electrode connected to the second data electrode 83 on the first 
nonlinear resistor layer 3 of the lower electrode 2, the display electrode 
7 on a part of the auxiliary electrode 127 and the first substrate 1, and 
the upper electrode 85 for a display electrode connected to the display 
electrode 7 on the first nonlinear resistor layer 3 of the lower electrode 
2, which are all made of the indium tantalum oxide (ITO) film. 
The connecting electrode 8 forming a part of the first anode oxide 
electrode 5 is connected to the second data electrode 83 and is made of 
indium tin oxide (ITO) film like the above second electrode. 
The lower electrode 2, the first nonlinear resistor layer 3 and the upper 
electrode 84 for a data electrode constitute the TFD structured first 
nonlinear resistor 86. 
Further, the lower electrode 2, the first nonlinear resistor layer 3 and 
the upper electrode 85 for a display electrode constitute the TFD 
structured second nonlinear resistor 87. 
A part of the display electrode 7 covers the auxiliary electrode 127 
connected to the second anode oxide electrode 126, and the display 
electrode 7 and the auxiliary electrode 127 constitute the shading 
portion. 
Still further, there is provided the insulating film 48 made of the 
tantalum oxide (Ta.sub.2 O.sub.5) film so as to cover the upper surfaces 
of the first substrate 1, the nonlinear resistors 86 and 87, the second 
data electrode 83, the display electrode 7, the first anode oxide 
electrode 5, and the second anode oxide electrode 126. 
The separating openings 92 are defined in the insulating film 48 and 
provided on the first anode oxide electrode 5 and the second anode oxide 
electrode 126. The first anode oxide electrodes 5 are separated at the 
separating side 10 which is the same as that of the separating openings 
92, thereby forming the independent first data electrode 82. The second 
anode oxide electrodes 126 are also separated from each other to 
constitute the independent auxiliary electrodes 127. 
Further, the openings 49 are defined at the periphery of the display 
electrodes 7, and the auxiliary electrodes 127 are separated from each 
other at the separating side 10 which is the same as that of the display 
electrode 7 or the opening 49 of the insulating film 48 of every display 
electrode 7, thereby forming the shading portion. 
With the arrangement of the ninth embodiment, the second anode oxide 
electrode 126 comprising the first electrode is made independent of the 
anode oxide electrode 5 from the first stage. Accordingly, the influence 
of the auxiliary electrode 127 is not given to the first anode oxide 
electrode 5. Further, the second anode oxide electrode 126 has the 
separating side 10 at which it is separated in self-matching manner from 
the display electrode 7 comprising the second electrode or the opening 49 
of the insulating film 48 at the periphery of the display region, thereby 
forming the independent shading portion on every display electrodes 7. 
Further, the second nonlinear resistor layer 128 provided on the auxiliary 
electrode 127 is made larger in film thickness than the first nonlinear 
resistor layer 3 provided on the lower electrode 2 by the first anode 
oxide electrode 5, thereby enhancing insulating property, so that the 
shading can be provided at the periphery of the display electrode 7 with 
excellent yield without influencing the display quality even if the 
display electrode 7 and the auxiliary electrode 127 of the display 
electrode 7 are electrically short circuited. 
Further, in the eighth and ninth embodiments of the invention, that the 
insulating film is provided for preventing the nonlinear resistor from 
being deteriorated mechanically when utilizing the first substrate having 
the nonlinear resistor for use in the liquid crystal display device, but 
the present invention is effective even if the insulating film is not 
provided. 
According to the fifth to ninth embodiments of the invention, a part of the 
anode oxide electrode can be utilized as the shading portion. 
Further, if there are a plurality of nonlinear resistors, the separation 
between the anode oxide electrode and the first signal electrode and the 
separation between the anode oxide electrode and the shading portion are 
carried out at the same time when the first signal electrode and the lower 
electrode are separated from each other. 
If there is the protection insulating film, the anode oxide electrode can 
be easily separated by defining the opening of the protection insulating 
film at a part where the anode oxide electrode is intended to be 
separated, and by performing the etching treatment while the resist which 
is utilized for forming the protection insulating film or the opening of 
the protection insulating film serves as the mask when the opening of the 
protection insulating film is formed so as to be connected to the external 
circuit. 
Tenth Embodiment 
A liquid crystal display device according to a tenth embodiment will be 
described next with reference to FIGS. 24 and 25. 
FIG. 24 is a plan view showing a part of a region of the first substrate 
forming the TFD element of the liquid crystal display device according to 
the tenth embodiment of the invention, and FIG. 25 is a cross sectional 
view taken along the line L--L in FIG. 24. 
The structure of the TFD element in this embodiment will be explained with 
reference to these figures. 
The anode oxide electrode 5 and the lower electrode 2 each made of tantalum 
(Ta) film as metal film are disposed on the first substrate 1 serving as 
an active substrate forming the TFD element. 
A width W1 of the anode oxide electrode 5 is wider than a width W2 of the 
signal electrode 4 at a part other than the periphery of the lower 
electrode 2. 
The anode oxide electrodes 5 are connected to each other by the runner part 
electrode 5a at one end thereof, and the other end thereof is connected to 
the connecting electrode 8 for applying a signal from the external circuit 
to the nonlinear resistor. The anode oxide electrode 5 is used as an 
electrode for forming the nonlinear resistor layer 3 on the surface of the 
lower electrode 2 by the anodic oxidation treatment. 
Accordingly, there is the anode oxide electrode 5 having the width W1 
between the signal electrode 4 and the display electrode 7. An etching 
removal part 121 which is a part of the anode oxide electrode 5 is removed 
in the final shape thereof. That is, FIG. 24 shows an intermediary stage 
of the manufacturing steps so as to make the explanation easy. 
Further, the nonlinear resistor layer 3 made of tantalum oxide (Ta.sub.2 
O.sub.5) film is provided on the surface of the lower electrode 2 which is 
formed by subjecting the lower electrode 2 to the anodic oxidation 
treatment. 
Further, an overlapping portion 122 which is a part of the anode oxide 
electrode 5 and a transparent conductive film on the first substrate 1 
form the display electrode 7. The upper electrode 6 connected to the 
display electrode 7 is provided on the lower electrode 2. Further, a 
transparent conductive film is also provided on the anode oxide electrode 
5 to form the connecting electrode 8. 
A part of the region of the display electrode 7 has the overlapping portion 
122 which overlaps a part of the region of the anode oxide electrode 5. 
The lower electrode 2, the nonlinear resistor layer 3 and the upper 
electrode 6 constitute the nonlinear resistor (TFD element) 9. 
Meanwhile, the upper electrode 6 and the display (electrode 7 are made of a 
transparent conductive film, e.g., a indium tin oxide (ITO) film. 
Further, the etching removal part 121 between the signal electrode 4 
composed of a part of the anode oxide electrode 5 and the overlapping 
portion 122 at the lower part of the display electrode 7 is removed, so 
that the signal electrode 4 and the display electrode 7 made of the 
transparent conductive film are separated from each other. 
The runner part electrodes 5a for connecting a plurality of signal 
electrodes 4 are also removed, so that the signal electrodes 4 are made 
independent of each other. 
The etching removal part 121 between the display electrodes 7 is also 
removed, so that the display electrodes 7 are also made independent of 
each other. 
Accordingly, the width W1 of the anode oxide electrode 5 becomes the width 
W2 as the signal electrode 4. 
That is, the width of the electrode as the anode oxide electrode 5 is W1 
before performing the anodic oxidation treatment, and the width W1 is made 
larger than the width W2 of the signal electrode 4, and it is widened 
toward the lower part of the display electrode 7. Further, the adjoining 
display electrodes 7 are connected by the anode oxide electrode 5. 
The anode oxide electrode 5 is subject to the etching treatment after the 
display electrode 7 is provided, then the etching removal part 121 which 
is a part of the anode oxide electrode 5 is removed, thereby permitting 
the width of the signal electrode 4 to become W2. Further, the etching 
removal part 121 between the adjoining display electrodes 7 is also 
removed, thereby forming the isolated display electrodes 7. 
With the employment of this structure, the anode oxide electrode 5 is 
widened (W1) in width at the time of anodic oxidation treatment so that 
the nonlinear resistor layer 3 can be formed uniformly in a short time. 
In case that the display electrode 7 is made of the transparent conductive 
film, it is normally difficult to inspect the etching condition at the 
periphery of the display electrode 7 since it is transparent. 
However, according to this embodiment, since the tantalum film and the 
tantalum oxide film are provided at the periphery of the display electrode 
7 as the anode oxide electrode 5, the tantalum or tantalum oxide film and 
the tantalum film remain while the transparent conductive film serves as 
an etching mask when the etching removal part 121 is subject to the 
etching treatment even if the display electrode 7 is made of transparent 
conductive film, so that the etching condition of the transparent 
conductive film at the periphery of the display electrode 7 can be easily 
inspected. 
Further, when the transparent conductive film remains slightly, the 
transparent conductive film can be also removed when the etching removal 
part 121 is subject to the etching treatment, so that an etching remaining 
film at the periphery of the display electrode 7 can be completely 
removed. 
Still further, since the width (W1) of the anode oxide electrode 5 is 
enlarged, it is possible to prevent the signal electrode 4 from being 
broken utilizing the anode oxide electrode 5 between the display electrode 
7 and the signal electrode 4 if there is a breakage within the width (W2) 
of the signal electrode 4. 
FIG. 26 is plan view showing a state where there occurs a breakage 4d in 
the signal electrode 4 in this embodiment. 
This figure shows a case that there occurs the breakage 4d which is deeper 
(depth W3) than the width (W2) of the signal electrode 4. If the signal 
electrode 4 remains to have the conventional electrode width W2, it will 
be broken. That is, it is impossible to perform the anodic oxidation 
treatment. Further, it is impossible to apply a voltage from outside to 
the nonlinear resistor (TFD element) 9. 
However, the anodic oxidation treatment can be performed in this embodiment 
since the width of the anode oxide electrode 5 is larger than the width W2 
of the signal electrode 4. Further, the signal electrode 4 will not be 
broken by the formation to detour the breakage of the signal electrode 4 
utilizing a part of the anode oxide electrode 5 formed at the periphery of 
the signal electrode 4. 
Further, the display electrode 7 has a removal part 7a which is removed at 
a part thereof for using a part of the overlapping portion 122 at the 
lower part of the display electrode 7 as a detouring part of the signal 
electrode 4. 
Since the width of the anode oxide electrode 5 is enlarged as mentioned 
above, it is possible to improve the uniformity of the anode oxide film 
and to prevent the anode oxide film from not being formed owing to the 
breakage of the signal electrode 4, thereby improving the yield and 
enhancing the characteristics of the anode oxide film. 
Next, a method of fabricating an active substrate of the liquid crystal 
display device according to the tenth embodiment will be now described. 
FIGS. 27 through 29 are cross-sectional views corresponding to FIG. 25 and 
showing the method of fabricating in the order of the fabricating steps. 
First of all, a tantalum (Ta) film as a metal film is formed on the entire 
surface of the first substrate 1 which is the active substrate made of 
glass in the film thickness of 150 nm by a sputtering technique as shown 
in FIG. 27. 
Thereafter, forming a photosensitive resin (not shown) on the entire 
surface of the tantalum film by a roll coating method, and subjecting the 
tantalum film to an exposing and developing treatment using a given 
photomask to thereby permit the photosensitive resin to be subject to a 
patterning treatment, thereafter patterning the anode oxide electrode 5, 
the lower electrode 2 and a part for connecting a plurality of signal 
electrodes 4 (anode oxide electrodes) by a photoetching treatment for 
etching the tantalum film employing the patterned photosensitive resin as 
an etching mask. 
The etching of the tantalum film is performed using a reactive ion etching 
(hereinafter referred to as RIE) system. 
As an etching condition, a mixture gas of sulfur hexafluoride (SF.sub.6) 
and oxygen (O.sub.2) is employed as an etching gas. The flow rate of the 
sulfur hexafluoride ranges from 100 to 200 sccm, and the flow rate of the 
oxygen ranges from 10 to 40 sccm at the pressure ranging from 4 to 
12.times.10.sup.-2 torr with the power ranging from 0.2 to 0.5 
kW/cm.sup.2. 
Thereafter, the tantalum film is subject to the anodic oxidation treatment 
by applying a voltage ranging from 30 to 40V thereto while permitting the 
anode oxide electrode 5 to be an anode using, an aqueous solution of 
citric acid ranging from 0.1 to 1.0 wt % or aqueous solution of ammonium 
borate as an anode oxide liquid. 
As a result, the nonlinear resistor layer 3 made of a tantalum oxide 
(Ta.sub.2 O.sub.5) film is formed on the side walls and upper surfaces, of 
the lower electrode 2 and anode oxide electrode 5 in a film thickness 
ranging from 60 to 75 nm. 
Thereafter, the indium tin oxide (ITO) film as the transparent conductive 
film is formed on the entire surface in a film thickness of 100 nm using a 
sputtering technique. Thereafter, a photosensitive resin (not shown) is 
formed on the indium tin oxide (ITO) film. 
Then the indium tin oxide (ITO) film is subject to the etching treatment, 
so as to simultaneously pattern the display electrode 7, the upper 
electrode 6 connected to the display electrode 7 and the connecting 
electrode 8 (not shown) as shown in FIG. 28. 
The etching of the indium tin oxide (ITO) film is performed by a wet 
etching technique using an aqueous solution etchant of ferric oxide and 
hydrochloric acid. An etchant liquid temperature at this time is set to 
range from 30.degree. C. to 40.degree. C. 
Thereafter, the photosensitive resin 125 is formed for subjecting the 
etching removal part 121, which is positioned between the anode oxide 
electrode 5 and the overlapping portion 122 at the lower part of the 
display electrode 7, to patterning as shown in FIG. 29. The etching 
removal part 121 is subject to the etching treatment using the RIE system 
while the display electrode 7 composed of the photosensitive resin 125 and 
the indium tin oxide film serve as an etching mask. 
As etching condition, a mixture gas of sulfur hexafluoride (SF.sub.6) and 
oxygen (O.sub.2) is employed as an etching gas. The flow rate of the 
sulfur hexafluoride (SF.sub.6) ranges from 100 to 200 sccm, and the flow 
rate of the oxygen ranges from 10 to 40 sccm at a pressure ranging from 4 
to 12.times.10.sup.-2 torr with power ranging from 0.2 to 0.5 kW/cm.sup.2. 
In the etching condition set forth above, the indium tin oxide film is 
hardly subject to the etching treatment but only the tantalum film and the 
tantalum oxide film of the nonlinear resistor layer 3 are subject to the 
etching treatment. 
Accordingly, the signal electrode 4 comprising a part of the anode oxide 
electrode 5 and the overlapping portion 122 of the display electrode 7 can 
be separated from each other by subjecting the etching removal part 121 to 
the etching treatment. 
With the above steps, as shown in FIG. 25 of the tenth embodiment, the 
anode oxide electrode 5 is separated from the display electrode 7 to form 
the signal electrode 4 so that an intended voltage can be applied to the 
display electrode 7 connected to the upper electrode 6 by way of the 
connecting electrode 8 connected to the external circuit (not shown), the 
signal electrode 4, the lower electrode 2 connected to the signal 
electrode 4, the nonlinear resistor layer 3 formed on the lower electrode 
2, and the upper electrode 6 formed on the nonlinear resistor layer 3. 
The lower electrode 2, the nonlinear resistor layer 3 and the upper 
electrode 6 constitute the nonlinear resistor (TFD element) 3. 
In this embodiment, when the anode oxide electrode 5 is processed by the 
etching treatment, the photosensitive resin 125 and the display electrode 
7 are used as an etching mask. Accordingly, the etching removal part 121 
can be formed in a shape which matches with the lower region of the 
display electrode 7. 
Accordingly, even in case that the indium tin oxide film remains thin or 
slightly on the etching removal part 121, namely, even if poor etching 
occurs, the transparent conductive film at the poor etching part between 
the signal electrode 4 and the display electrode 7 can be removed at the 
same time when the etching removal part 121 is subject to the etching 
treatment. 
Further, the inspection of the short circuited part can be very easily 
performed compared with the case comprising only the transparent 
conductive film since the indium tin oxide film remains on the etching 
removal part 121 in case that the indium tin oxide film remains on a large 
surface upon completion of the etching treatment so that tantalum oxide as 
the nonlinear resistor layer 3 and tantalum as the lower electrode 2 
remain at the lower part of the indium tin oxide film. 
Still further, it is very difficult to detect the etching remaining film of 
the transparent conductive film at the periphery of the display electrode 
7 owing to the refractive index of the liquid crystal, the thickness of 
the first substrate 1 or the refractive index of the orientational films, 
etc. after the first substrate 1 and the second substrate (not shown) are 
bonded to each other and the liquid crystal is filled therebetween as the 
liquid crystal display device. 
Also in this case, the detection can be easily performed since the 
tantalum, etc. remain as the etching remaining film. 
Eleventh Embodiment 
A liquid crystal display device according to an eleventh embodiment of the 
invention will be described next with reference to FIGS. 30 and 31. 
FIG. 30 is a plan view showing a region of a part of the first substrate 
forming a TFD element of the liquid crystal display device according to 
the eleventh embodiment, and FIG. 31 is a cross-sectional view taken along 
the line M--M in FIG. 30. 
The structure of the TFD element of the eleventh embodiment will be 
described with reference to these figures. 
The anode oxide electrode 5, the island-shaped lower electrode 2, the line 
connecting part 76 (shown by an imaginary line) for connecting the anode 
oxide electrode 5 and the lower electrode 2 each made of tantalum (Ta) 
film as metal film are disposed on the first substrate 1. 
The anode oxide electrode 5 has a width W1 which is larger than the width 
W2 of the first data electrode 82 at a part other than the periphery of 
the island-shaped lower electrode 2. 
The anode oxide electrodes 5 are connected to each other in plural numbers 
by the runner part 5a at one end thereof, and they are covered with the 
connecting electrode 8 for applying a signal from an external circuit to 
the nonlinear resistor 9 at the other end thereof. 
The anode oxide electrode 5 is used as an electrode for forming the 
nonlinear resistor layer 3 on the surface of the lower electrode 2 by the 
anodic oxidation treatment. 
The anode oxide electrode 5 is provided between the first data electrode 82 
and the display electrode 7. The etching removal part 121 forming a part 
of the anode oxide electrode 5 is removed in the final structure. 
Further, the first data electrode 82 and the line connecting part 76 
connected to the island-shaped lower electrode 2 are also removed in the 
final structure. That is, the plan view in FIG. 30 and the cross-sectional 
view in FIG. 31 show an intermediary stage of the manufacturing steps 
denoted by imaginary lines so as to make the explanation easy. 
Further, the nonlinear resistor layer 3 made of the tantalum oxide 
(Ta.sub.2 O.sub.5) film, which is formed by subjecting the tantalum film 
to the anodic oxidation treatment, is provided on the surfaces of the 
anode oxide electrode 5 and the island-shaped lower electrode 2 by way of 
the line connecting part 76. 
The transparent conductive film is provided on the overlapping portion 122 
of the anode oxide electrode 5 and the first substrate 1 to form the 
display electrode 7. Further, the upper electrode 85 for a display 
electrode connected to the display electrode 7 is provided on the lower 
electrode 2. Still further, the second data electrode 83 is provided on 
the anode oxide electrode 5, and the upper electrode 84 for a data 
electrode connected to the second data electrode 83 is provided. 
The connecting electrode 8 made of transparent conductive film is provided 
on the anode oxide electrode 5 made of tantalum for applying the signal 
from the external circuit to the nonlinear resistor. In the connecting 
electrode 8, tantalum of the anode oxide electrode 5 has a frame shape. 
The connecting electrode 8 made of the transparent conductive film covers 
frame-shaped tantalum. 
With the provision of this shape, the matching accuracy is improved since 
the position can be clearly identified by frame-shaped tantalum compared 
with that of the transparent conductive film in the case of connecting the 
external circuit and the connecting electrode 8. Further, the connecting 
state between the external circuit and the input part can be verified 
through a transparent conductive film pad part by providing the 
transparent conductive film inside and outside the frame-shaped tantalum. 
Particularly, the matching accuracy is improved by providing tantalum in 
the frame shape since it is inferior using only the transparent conductive 
film in the case of a so-called chip-on-glass (COG) method for directly 
connecting the integrated circuit (IC) and the input part onto the 
connecting electrode 8 by way of a medium such as a conductive paste, etc. 
The island-shaped lower electrode 2, the nonlinear resistor layer 3 and the 
upper electrode 84 for a data electrode constitute the first nonlinear 
resistor (TFD element) 86. Further, the island-shaped lower electrode 2, 
the nonlinear resistor layer 3 and the upper electrode 85 for a display 
electrode constitute the second nonlinear resistor (TFD element) 87. 
The upper electrode 85 for a display electrode, the upper electrode 84 for 
a data electrode and the display electrode 7 are all made of the 
transparent conductive film, e.g., indium tin oxide (ITO) film. 
Further, the anode oxide electrode 5 has a structure that it is separated 
into the overlapping portion 122 where the anode oxide electrode 5 and the 
display electrode 7 made of the transparent conductive film overlap, and 
the first data electrode 82 made of tantalum at the lower part of the 
second data electrode 83. The etching removal part 121 between the first 
data electrode 82 and the display electrode 7 is removed to be separated 
from the display electrode 7. 
Accordingly, the width W1 of the anode oxide electrode 5 becomes W2 as the 
first data electrode 81. 
Consequently, the anode oxide electrode 5 is widened as the width W1 which 
is larger than the width W2 of the first data electrode 82 at the time of 
anodic oxidation treatment, and it is widened toward the lower part of the 
display electrode 7. Further, the adjoining display electrodes 7 are 
connected to each other by the anode oxide electrode 5. 
The line connecting part 76 for connecting the first data electrode 82 and 
the island-shaped lower electrode 2 is subject to the etching treatment 
after the second data electrode 83 and the display electrode 7 are 
provided, thereby forming the isolated island-shaped lower electrode 2, 
and at the same time the etching removal part 121 between the first data 
electrode 82 and the display electrode 7 is subject to the etching 
treatment so as to form the isolated display electrode 7 and the first 
data electrode 82. 
With the employment of this structure, since the anode oxide electrode 5 is 
large in width as denoted by W1 at the time of anodic oxidation treatment, 
the anode oxide film can be formed uniformly in a short time. 
Further, since the width of the anode oxide electrode is enlarged like the 
case in FIG. 26, it is possible to prevent the breakage of the first data 
electrode 82 utilizing the anode oxide electrode 5 between the display 
electrode 7 and the data electrodes 82 and 83 if there is a breakage 
within the width W2 of the first data electrode 82. 
Further, the island-shaped lower electrode 2 requires to be separated from 
the first data electrode 82 according to this embodiment, however it does 
not lead to the increase of steps because a step to process the first data 
electrode 82 from the anode oxide electrode 5 can be performed at the same 
time. 
Successively, a method of fabricating an active substrate of the liquid 
crystal display device according to the eleventh embodiment will be 
described with reference to FIGS. 32 through 34. 
FIGS. 32 through 34 are cross-sectional views corresponding to FIG. 31 and 
showing in the order of fabricating steps of the active substrate of the 
liquid crystal display device according to the eleventh embodiment of the 
invention. 
First of all, a tantalum (Ta) film as a metal film is formed on the entire 
surface of the first substrate 1 serving as the active substrate made of 
glass shown in FIG. 32 in the film thickness of 200 nm by a sputtering 
technique. 
Thereafter, a photosensitive resin (not shown) is formed on the entire 
surface of the tantalum film by a roll coating method, and the tantalum 
film is subject to an exposing and developing treatment using a given 
photomask to thereby permit the photosensitive resin to be subject to 
patterning. 
Thereafter, the anode oxide electrode 5 including the part forming the 
first data electrode 82, the island-shaped lower electrode 2, the line 
connecting part 76 for connecting the anode oxide electrode 5 and the 
island-shaped lower electrode 2, and a plurality of anode oxide electrodes 
5 are patterned so as to be connected to each other by a photoetching 
treatment for etching the tantalum film employing the patterned 
photosensitive resin as an etching mask. 
The etching of the tantalum film is performed using a RIE system. 
As etching condition, a mixture gas of sulfur hexafluoride (SF.sub.6) and 
oxygen (O.sub.2) is employed as an etching gas. The flow rate of the 
sulfur hexafluoride ranges from 100 to 200 sccm, and the flow rate of the 
oxygen ranges from 10 to 40 sccm at a pressure ranging from 4 to 
12.times.10.sup.-2 torr with power ranging from 0.2 to 0.5 kW/cm.sup.2. 
Thereafter, the tantalum film is subject to the anodic oxidation treatment 
by applying a voltage ranging from 16 to 20 V thereto while permitting the 
anode oxide electrode 5 to be an anode using aqueous solution of citric 
acid ranging from 0.01 to 1.0 wt % or aqueous solution of ammonium borate 
or aqueous solution of phosphoric acid as an anode oxidation liquid. 
As a result, the nonlinear resistor layer 3 made of the tantalum oxide 
(Ta.sub.2 O.sub.5) film is formed on the side walls and upper surfaces of 
the lower electrode 2 and anode oxide electrode 5 in the film thickness 
ranging from 30 to 40 nm. 
Thereafter, the indium tin oxide (ITO) film as the transparent conductive 
film is formed on the entire surface in a film thickness of 150 nm using a 
sputtering technique. Thereafter, a photosensitive resin (not shown) is 
formed on indium tin oxide (ITO) film. 
Then the indium tin oxide (ITO) film is subject to the etching treatment so 
as to simultaneously pattern the display electrode 7, the upper electrode 
85 for a display electrode connected to the display electrode 7, the 
connecting electrode 8, the second data electrode 83, and the upper 
electrode 84 for a data electrode connected to the second data electrode 
83 as shown in FIG. 33. 
The etching treatment of the indium tin oxide is performed by wet etching 
using an etchant of the aqueous solution of hydrogen bromine (HBr). The 
etchant liquid temperature at this time is set to range from 25.degree. C. 
to 30.degree. C. 
Then, as shown in FIG. 34, the photosensitive resin 15 is formed by 
removing the line connecting part 76 for connecting the anode oxide 
electrode 5 and the island-shaped lower electrode 2, thereby forming the 
isolated island-shaped lower electrode 2. At this time, the etching 
removal part 121 which is a part of the anode oxide electrode 5 is removed 
so that the anode oxide electrode 5 is separated into the first data 
electrode 82 and the overlapping portion 122 at the lower part of the 
display electrode 7. 
The anode oxide electrode 5 is subject to the etching treatment using a RIE 
system utilizing the photosensitive resin 125, the display electrode 7 
made of the indium tin oxide film and the second data electrode 83 as an 
etching mask. 
As etching condition, a mixture gas of sulfur hexafluoride (SF.sub.6) and 
oxygen (O.sub.2) is employed as an etching gas. The flow rate of the 
sulfur hexafluoride ranges from 100 to 200 sccm, and the flow rate of the 
oxygen ranges from 10 to 40 sccm at a pressure ranging from 4 to 
12.times.10.sup.-2 torr with power ranging from 0.2 to 0.5 kW/cm.sup.2. 
In the etching condition set forth above, the indium tin oxide film is 
hardly subject to the etching treatment and only the tantalum film and the 
tantalum oxide film of the line connecting part 76 and the etching removal 
part 121 are subject to the etching treatment. 
With the above steps, the anode oxide electrode 5 is separated into the 
first data electrode 82 and the overlapping portion 122 at the lower part 
of the display electrode 7 as shown in FIG. 31, so that the' signal issued 
from the external circuit can be supplied through a passage described as 
follows. 
That is, an intended voltage is applied to the display electrode 7 
connected to the upper electrode 85 for a display electrode by way of the 
connecting electrode 8 connected to the external circuit (riot shown), the 
first data electrode 82 connected to the anode oxide electrode 5, the 
second data electrode 83, the upper electrode 84 for a data electrode 
connected to the second data electrode 83, the nonlinear resistor layer 3, 
the island-shaped lower electrode 2, the nonlinear resistor layer 3 and 
the upper electrode 85 for a display electrode. 
In this embodiment, the etching treatment is performed for separating the 
island-shaped lower electrode 2 utilizing the photosensitive resin 125, 
the display electrode 7 and the second data electrode 83 as an etching 
mask. At this time, since the etching removal part 121 between the first 
data electrode 82 and the overlapping portion 122 in the anode oxide 
electrode 5 is removed, the number of steps is not increased. 
Twelfth Embodiment 
A liquid crystal display device according to a twelfth embodiment of the 
invention will be described next with reference to FIGS. 35 and 36. 
FIG. 35 is a plan view showing a region of a part of the first substrate 
for forming a TFD element of the liquid crystal display device according 
to the twelfth embodiment. FIG. 36 is a cross-sectional view taken along 
the line N--N in FIG. 35. 
In this embodiment, the anode oxide electrode 5 in the eleventh embodiment 
extends to the upper and lower sides and the right and left sides of the 
display electrode 7 so as to form the overlapping portions 122 on the 
upper and lower sides and the right and left sides of the display 
electrode 7. 
The anode oxide electrode 5, the island-shaped lower electrode 2, the line 
connecting part 76 for connecting the anode oxide electrode 5 and the 
lower electrode 2 (shown by imaginary lines in FIG. 35) are made of 
tantalum (Ta) film as a metal film and disposed on the first substrate 1. 
The width of the anode oxide electrode 5 has the width W1 which is larger 
than the width W2 of the first data electrode 82 at a part other than the 
island-shaped lower electrode 2. Further the anode oxide electrodes 5 are 
connected to each other at the upper and lower sides and right and left 
sides thereof. 
The anode oxide electrodes 5 have structures that they are connected to 
each other in plural numbers by the runner parts 5a at ones end thereof, 
and the other end of the anode oxide electrode 5 is covered with the 
connecting electrode 8 for applying the signal from the external circuit 
to the nonlinear resistor. The anode oxide electrode 5 is used as an 
electrode for forming the nonlinear resistor layer 3 on the surface of the 
lower electrode 2 by the anodic oxidation treatment. 
The anode oxide electrodes 5 are provided between the first data electrode 
82 and the display electrode 7 and between the display electrodes 7 and 
the display electrode 7 in FIG. 35. The etching removal part 121 forming a 
part of the anode oxide electrode 5 is removed in the final structure. 
Further, the first data electrode 82 and the line connecting part 76 
connected to the island-shaped lower electrode 2 are also removed in the 
final structure. That is, the plan view in FIG. 35 and the cross-sectional 
view in FIG. 36 show an intermediary stage of the manufacturing steps by 
an imaginary line so as to make the explanation easy. 
Further, the nonlinear resistor layer 3 made of the tantalum oxide 
(Ta.sub.2 O.sub.5) film, which is formed by subjecting the tantalum film 
to the anodic oxidation treatment, is provided on the surfaces of the 
anode oxide electrode 5 and the island-shaped lower electrode 2 by way of 
the line connecting part 76. 
The transparent conductive film is provided on the overlapping portion 122 
of the anode oxide electrode 5 and the substrate 1 to form the display 
electrode 7. Further, the upper electrode 85 for a display electrode 
connected to the display electrode 7 is provided on the lower electrode 2. 
Still further, the second data electrode 83 is provided on the anode oxide 
electrode 5, and the upper electrode 84 for a data electrode connected to 
the second data electrode 83 is provided. 
Further, the connecting electrode 8 made of the transparent conductive film 
is provided on the anode oxide electrode 5 made of tantalum for applying 
the signal from the external circuit to the nonlinear resistor. In the 
connecting electrode 8, tantalum of the anode oxide electrode 5 has a 
frame shape. The transparent conductive film covers the frame-shaped 
tantalum. With the provision of this shape, the matching accuracy is 
improved since the position can be clearly identified by frame-shaped 
tantalum compared with that of the transparent conductive film in the case 
of connecting the external circuit and the connecting electrode 8. The 
connecting state between the external circuit and the input part can be 
verified through a transparent conductive film pad part by providing the 
transparent conductive film inside and outside frame-shaped tantalum. 
Particularly, the matching accuracy is improved by providing tantalum in 
the frame shape since it is inferior using only the transparent conductive 
film in the case of a so-called chip-on-glass (COG) method for directly 
connecting the integrated circuit (IC) and the input part onto the 
connecting electrode 8 by way of a medium such as a conductive paste, etc. 
The island-shaped lower electrode 2, the nonlinear resistor layer 3 and the 
upper electrode 84 for a data electrode constitute the first nonlinear 
resistor (TFD element) 86. Further, the island-shaped lower electrode 2, 
the nonlinear resistor layer 3 and the upper electrode 85 for a display 
electrode constitute the second nonlinear resistor (TFD element) 87. 
The upper electrode 85 for a display electrode, the upper electrode 84 for 
a data electrode and the display electrode 7 are all made of the 
transparent conductive film, e.g., indium tin oxide (ITO) film. 
Further, the anode oxide electrode 5 has a structure that it is separated 
into the overlapping portion 122 where the anode oxide electrode 5 and the 
display electrode 7 made of the transparent conductive film overlap, and 
the first data electrode 82 made of tantalum at the lower part of the 
second data electrode 83. The etching removal part 121 between the first 
data electrode 82 and the display electrode 7 is removed so as to be 
separated from the display electrode 7. 
Accordingly, the width of the anode oxide electrode 5 becomes W2 as the 
first data electrode 82. 
Accordingly, the anode oxide electrode 5 is widened as the width W1 which 
is larger than the width (W2) of the first data electrode 82 at the time 
of anodic oxidation treatment, and it is widened toward the lower part of 
the display electrode 7. Further, the adjoining display electrodes 7 are 
connected to each other by the anode oxide electrode 5. 
The line connecting part 76 for connecting the first data electrode 82 and 
the island-shaped lower electrode 2 is subject to the etching treatment 
upon completion of the provision of the second data electrode 83 and the 
display electrode 7, thereby forming the isolated island-shaped lower 
electrode 2, and at the same the etching removal part 121 between the 
first data electrode 82 and the display electrode 7 is subject to the 
etching treatment so as to form the isolated display electrode 7 and the 
first data electrode 82. 
With the employment of this structure, since the anode oxide electrode 5 is 
enlarged in width and it traverses up and down and right and left at the 
time of anodic oxidation treatment, the anode oxide film can be formed 
uniformly in a short time. 
Other functions and effects are the same as those of the eleventh 
embodiment. 
Thirteenth Embodiment 
A liquid crystal display device according to a thirteenth embodiment of the 
invention will be described next with reference to FIGS. 37 and 38. 
FIG. 37 is a plan view showing a region of a part of the first substrate 
for forming a TFD element of the liquid crystal display device according 
to the thirteenth embodiment, and FIG. 38 is a cross-sectional view taken 
along the line P--P in FIG. 37. 
The structure of the TFD element of the thirteenth embodiment will be 
described with reference to these figures. 
In this embodiment, in addition to the steps in the eleventh embodiment, 
the insulating film 48 is formed and the opening 91 is defined in the 
insulating film 48, and the line connecting part 76 for connecting the 
island-shaped lower electrode 2 and the first data electrode 82 is subject 
to the etching treatment so as to be removed utilizing the opening 91. 
Further, the opening 91 of the insulating film 48 is defined between the 
first data electrode 82 or the second data electrode 83 and the display 
electrodes 7 or between the display electrode 7 and the display electrode 
7 so as to remove a part of the anode oxide electrode 5, namely, the 
etching removal part 121 so that the first data electrode 82 and the 
display electrode 7 are separated from each other. 
The anode oxide electrode 5, the island-shaped lower electrode 2 and the 
line connecting part 76 for connecting the anode oxide electrode 5 and the 
lower electrode 2 (as shown by imaginary lines) are made of tantalum (Ta) 
film as metal film and disposed on the first substrate 1. 
The anode oxide electrode 5 has the width W1 which is larger than the width 
W2 of the first data electrode 82 at a part other than the periphery of 
the island-shaped lower electrode 2. 
The anode oxide electrodes 5 are connected to each other in plural numbers 
by the runner parts 5a at one end thereof, and the other ends of the anode 
oxide electrode 5 are covered with the connecting electrode 8 for applying 
the signal from the external circuit to the nonlinear resistor. 
The anode oxide electrode 5 is used as an electrode when the nonlinear 
resistor layer 3 is formed on the surface of the lower electrode 2 by the 
anodic oxidation treatment. 
The anode oxide electrode 5 is provided between the first data electrode 82 
and the display electrode 7 as shown in FIG. 31. The etching removal part 
121 is removed in the final structure. 
Further, the first data electrode 82 and the line connecting part 76 
connected to the island-shaped lower electrode 2 are also removed in the 
final structure. That is, FIG. 37 and FIG. 38 show an intermediary stage 
of the manufacturing steps by imaginary lines so as to make the 
explanation easy. 
Further, the nonlinear resistor layer 3 made of tantalum oxide (Ta.sub.2 
O.sub.5) film, which is formed by subjecting the tantalum film to the 
anodic oxidation treatment, is provided on the surfaces of the anode oxide 
electrode 5 and the island-shaped lower electrode 2 by way of the line 
connecting part 76. 
In case that the anodic oxidation treatment is performed, the line 
connecting parts 76 are provided vertically in two directions of the lower 
electrode 2, the anode oxide film can be formed on the surface of the 
lower electrode 2 without any trouble, since the anode oxide electrode 5 
is connected to the other line connecting part 76, for example, Even if 
one line connecting part 76 is broken. 
Further, the transparent conductive film is provided on the overlapping 
portion 122 of the anode oxide electrode 5 and the first substrate 1, 
thereby forming the display electrode 7. Further, the upper electrode 85 
for a display electrode connected to the display electrode 7 is provided 
on the lower electrode 2. Still further, the second data electrode 83 is 
provided on the anode oxide electrode 5, and the upper electrode 84 for a 
data electrode connected to the second data electrode 83 is further 
provided. 
Further, the connecting electrode 8 made of the transparent conductive film 
is provided on the anode oxide electrode 5 made of tantalum for applying 
the signal from the external circuit to the nonlinear resistor. In the 
connecting electrode 8, tantalum has a frame shape. The transparent 
conductive film covers frame-shaped tantalum and has a square shape. With 
the provision of this shape, the matching accuracy is improved since the 
position can be clearly identified by the frame-shaped tantalum compared 
with that of the transparent conductive film in the case of connecting the 
external circuit and the connecting electrode 8. 
Further, the connecting state between the external circuit and the input 
part can be verified through a transparent conductive film by providing 
the transparent conductive film inside and outside frame-shaped tantalum. 
The island-shaped lower electrode 2, the nonlinear resistor layer 3 and the 
upper electrode 84 for a data electrode constitute the first nonlinear 
resistor (TFD element) 86. Further, the island-shaped lower electrode 2, 
the nonlinear resistor layer 3 and the upper electrode 85 for a display 
electrode constitute the second nonlinear resistor (TFD element) 87. 
The upper electrode 85 for a display electrode, the upper electrode 84 for 
a data electrode and the display electrode 7 are made of the transparent 
conductive film, e.g., indium tin oxide (ITO) film. 
The insulating film 48 is formed on the entire surface for preventing the 
nonlinear resistor (TFD) from being deteriorated or broken by an external 
force when the nonlinear resistor (TFD) is processed to be adapted for the 
liquid crystal display device, or for preventing electric short circuit 
between the second data electrode 83 and the opposed electrode (not shown) 
constituting the liquid crystal display device, or between the display 
electrode 7 and the opposed electrode (not shown). 
The insulating film 48 is made of tantalum oxide (Ta.sub.2 O.sub.5) film by 
the sputtering technique. 
The line connection opening 91 (shown by one-dotted chain line) for 
removing the line connecting part 76 is defined in the insulating film 48. 
Further, the separating opening 92 is also defined in the etching removal 
part 121 between the anode oxide electrode 5 and the overlapping portion 
122 of the display electrode 7. 
Further, in the connecting electrode 8, the connection opening 93 of the 
insulating film 48 is provided on the connecting electrode 8 made of the 
transparent conductive film, and the insulating film 48 remains on the 
other part. 
In the connecting electrode 8, when the insulating film 48 remains on a 
region other than the connecting electrode 8 connected to the external 
circuit as set forth above, the insulating film 48 covers substantially 
the entire wiring, so that the adjoining input part and the lines are 
prevented from being short-circuited owing to dust, etc. 
The line connecting part 76 has a side which is the saute as that of the 
line connection opening 91 of the insulating film 48 and those of the 
display electrode 7, while the island-shaped lower electrode 2 has a side 
which is the same as that of the line connection opening 91 extending from 
the anode oxide electrode 5. The etching removal part 121 has a side which 
is the same as that of the separating openings 92 of the insulating film 
48 and those of the display electrode 7, wherein the anode oxide electrode 
5 becomes the first data electrode 81 by the etching removal part 121, 
thereby constituting the independent display electrodes 7. 
Accordingly, the width of the anode oxide electrode 5 becomes the width W2 
as the first data electrode 82. 
Accordingly, when the anodic oxidation treatment is performed, the width of 
the anode oxide electrode 5 is denoted by W1 and is made larger than the 
width W2 of the first data electrode 81, and it is widened toward the 
lower part of the display electrode 7. Further, the adjoining display 
electrodes 7 are also connected to each other by the anode oxide electrode 
5. 
Finally, the second data electrode 83 and the display electrode 7 are 
provided, further the line connecting part 76 for connecting the first 
data electrode 82 and the island-shaped lower electrode 2 is subject to 
the etching treatment upon completion of the provision of the insulating 
film 48 so as to form the isolated island-shaped lower electrode 2, then 
at the same time the etching removal part 121 between the first data 
electrode 82 and the display electrode 7 is subject to the etching 
treatment, thereby forming the isolated display electrode 7 and the first 
data electrode 81. 
With the employment of this structure, the anode oxide electrode is 
enlarged in width at the time of anodic oxidation treatment so that the 
anode oxide film can be formed uniformly in a short time. 
Further, since the width (W1) of the anode oxide electrode is enlarged like 
the case in FIG. 26, it is possible to prevent breakage of the first data 
electrode 82 utilizing a part of the anode oxide electrode 5 between the 
display electrode 7 and the first data electrode 82 if there is a breakage 
within the width (W2) of the first data electrode 82. 
Further, according to this embodiment, the island-shaped lower electrode 2 
is required to be separated from the first data electrode 82, and further 
it is necessary to perform an electrical connection with an external 
circuit by defining the opening in the insulating film 48 in the 
connecting electrode 8. Accordingly, at the same time when processing the 
insulating film 48, the removal of the line connecting part 76 and the 
processing of the first data electrode 82 from the anode oxide electrode 5 
can be performed, which does not lead to the increase of the number of 
steps at all. 
Further, when the insulating film 48 is provided on the second data 
electrode 83 or the display electrode 7, there does not occur electrical 
short circuit with the opposed electrode which is used when utilizing as 
the liquid crystal display device. 
Still further, although two upper electrodes are provided in this 
embodiment, two or more upper electrodes may be provided. 
Fourteenth Embodiment 
A liquid crystal display device according to a fourteenth embodiment of the 
invention will be described next with reference to FIGS. 39 and 40. 
The fourteenth embodiment relates to the structure of a TFT element. 
FIG. 39 is a plan view showing a region of a part of the first substrate 
for forming the TFT element of the liquid crystal display device according 
to the fourteenth embodiment, and FIG. 40 is a cross-sectional view taken 
along the line Q--Q in FIG. 39. 
The anode oxide electrode 5 and the gate electrode 101 forming a part of 
the anode oxide electrode 5 are made of tantalum (Ta) film as metal film 
and disposed on the first substrate 1 serving as an active substrate 
forming the TFT element. The anode oxide electrode 5 comprises the gate 
electrode 101, the etching removal part 121 and the overlapping portion 
122. 
The width of the anode oxide electrode 5 is denoted by W1 and is large at a 
part other than the periphery of the gate electrode 101. 
The anode oxide electrodes 5 are connected to each other in plural numbers 
by the anode oxide electrode parts, not shown, at one end thereof. The 
anode oxide electrodes 5 are covered with the connecting electrode 8 for 
applying a signal from an external circuit to the TFT element at the other 
end thereof. The anode oxide electrode 5 is used as an electrode for 
forming the gate insulating film 102 on the surface of the gate electrode 
101 by the anodic oxidation treatment. 
A part of the anode oxide electrode 5 is provided between the gate 
electrode 101 and the display electrode 7 as shown in FIG. 39. The etching 
removal part 121 which is a region other than the display electrode 7 is 
removed in the final structure. 
That is, these figures show an intermediary stage of the manufacturing 
steps by an imaginary line so as to make the explanation easy. 
Further, the gate insulating film 102 made of the tantalum oxide (Ta.sub.2 
O.sub.5) film, which is formed by subjecting the tantalum film to the 
anodic oxidation treatment, is provided on the surfaces of the anode oxide 
electrode 5 and the gate electrode 101. 
A semiconductor layer 103 made of amorphous silicon (a-Si) is provided at 
the periphery of the gate electrode 101. Further, a semiconductor layer 
104 containing phosphorus (P) as an impurity ion is provided on the 
semiconductor layer 103. 
A source electrode 105 and a drain electrode 106 are provided on the 
semiconductor layer 104 containing the impurity ion. The source electrode 
105 and the drain electrode 106 are made of molybdenum (Mo). The 
semiconductor layer 104 containing the impurity ions is provided on an 
overlapping part where the source electrode 105, the drain electrode 106 
and the semiconductor layer 103 overlap. Further, the source electrode 105 
is connected to the data electrode 81 which is connected to the external 
circuit. 
At the part where the data electrode 81 and the gate electrode 101 overlap, 
the gate electrode 101 comprises the metal film (tantalum) 2 and the anode 
oxide film (tantalum oxide) 3, and the semiconductor layer 103, the 
semiconductor layer 104 containing the impurity ions and the metal film 
(molybdenum) of the source electrode 105 are provided thereon. 
In such a manner, the electric short circuit can be more effectively 
prevented by providing a multiple-layered insulating film or the 
semiconductor layer 103 between the metal film of the gate electrode 101 
and the metal film of the source electrode 105. 
Further, the display electrode 7 is provided on the overlapping portion 122 
of the anode oxide electrode 5 and the first substrate 1. 
The connecting electrode 8 made of the transparent conductive film is 
provided on the anode oxide electrode 5 made of tantalum film for applying 
a signal from the external circuit to the nonlinear resistor. In the 
connecting electrode 8, tantalum has a frame shape. Further, the 
transparent conductive film covers frame-shaped tantalum, and has a square 
shape. 
With the provision of this shape, the matching accuracy is improved since 
the position can be clearly identified by frame-shaped tantalum compared 
with that of the transparent conductive film in the case of connecting the 
external circuit and the connecting electrode 8. Further, the connecting 
state between the external circuit and the connecting electrode 8 can be 
verified through a transparent conductive film by providing the 
transparent conductive film inside and outside frame-shaped tantalum. 
The display electrode 7 and the connecting electrode 23 are made of the 
transparent conductive film, e.g., indium tin oxide (ITO) film. 
Further, the etching removal part 121 between the display electrode 7 and 
the gate electrode 101 in the anode oxide electrode 5 is subject to the 
etching treatment so as to be removed, and the anode oxide electrode 5 
becomes the gate electrode 101 and is separated from the overlapping 
portion 122 at the lower part of the display electrode 7. 
Accordingly, the width of the anode oxide electrode 5 becomes W2 as the 
gate electrode 101. 
Consequently, at the time of the anodic oxidation treatment, the width of 
the anode oxide electrode 5 denoted by W1 is larger than the width (W2) of 
the gate electrode 101, and it is enlarged toward the lower part of the 
display electrode 7. Further, the adjoining display electrodes 7 are 
connected to each other by the anode oxide electrode 5. 
Finally, the gate electrode 101 and the overlapping portion 122 at the 
lower part of the display electrode 7 are separated from each other upon 
completion of the provision of the display electrode 7. Further the 
isolated display electrodes 7 are formed. 
With the employment of this structure, the anode oxide electrode is 
enlarged in width at the time of anodic oxidation treatment, so that the 
anode oxide film can be formed uniformly in a short time. 
Further, since the width (W1) of the anode oxide (electrode 5 is enlarged, 
it is possible to prevent breakage of the gate electrode 101 utilizing a 
part of the anode oxide electrode 5 between the display electrode 7 and 
the gate electrode 101 if there is a breakage within the width (W2) of the 
gate electrode 101. 
A method of fabricating an active substrate of the liquid crystal display 
device according to the fourteenth embodiment will be described with 
reference to FIGS. 41 through 44. 
FIGS. 41 through 44 are cross-sectional views showing, the steps of 
fabricating the active substrate of the liquid crystal display device in 
the order of fabricating steps according to the fourteenth embodiment. 
First of all, a tantalum (Ta) film as a metal film is formed on the entire 
surface of the first substrate 1 forming the active substrate made of 
glass shown in FIG. 41 in a film thickness of 200 nm by a sputtering 
technique. 
Thereafter, forming a photosensitive resin (not shown) on the entire 
surface of the tantalum film by a spin coating method, and subjecting the 
tantalum film to an exposing and developing treatment using a given 
photomask to thereby permit the photosensitive resin to be subject to 
patterning, thereafter patterning the anode oxide electrode 5 and the gate 
electrode 101 connected to the anode oxide electrode 5 by a photoetching 
treatment for etching the tantalum film employing the patterned 
photosensitive resin as an etching mask. 
The etching of the tantalum film is performed using a RIE system. 
As an etching condition, a mixture gas of sulfur hexafluoride (SF.sub.6) 
and oxygen (O.sub.2) is employed as an etching gas. The flow rate of the 
sulfur hexafluoride ranges from 100 to 200 sccm, and the flow rate of the 
oxygen ranges from 10 to 40 sccm at a pressure ranging from 4 to 
12.times.10.sup.-2 torr with power ranging from 0.2 to 0.5 kW/cm.sup.2. 
Thereafter, the tantalum film is subject to the anodic oxidation treatment 
by applying a voltage ranging from 60 to 70V thereto while permitting the 
anode oxide electrode 5 to be an anode using aqueous solution of citric 
acid ranging from 0.1 to 1.0 wt % or aqueous solution of ammonium borate 
or aqueous solution of phosphoric acid as the anode oxidation liquid. 
As a result, the insulating film (not shown) made of the tantalum oxide 
(Ta.sub.2 O.sub.5) film is formed on the side walls and upper surfaces of 
the gate electrode 101 and the anode oxide electrode 5 in the film 
thickness ranging from 120 to 130 nm. 
Successively, an amorphous silicon (a-Si) film as the semiconductor layer 
103 is formed on the entire surface in a thickness of 70 nm using a plasma 
CVD technique. Thereafter, the semiconductor layer 104 (n-a-Si) containing 
phosphorus (P) as an impurity ion is formed on the entire surface in a 
thickness of 20 nm using the plasma CVD technique. 
Thereafter, as shown in FIG. 42, the semiconductor layers 103 and 104 are 
subject to the etching treatment so as to pattern the periphery of the 
gate electrode 101 and the part of the data electrode 81. 
The etching of the amorphous silicon film is performed using the RIE 
system. 
As etching condition, a mixture gas of carbon tetrafluoride (CF.sub.4) and 
oxygen (O.sub.2) is employed as an etching gas. The flow rate of the 
carbon tetrafluoride ranges from 100 to 200 sccm, and the flow rate of the 
oxygen ranges from 10 to 40 sccm at a pressure ranging from 4 to 
12.times.10.sup.-2 torr with power ranging from 0.2 to 0.5 kW/cm.sup.2. 
Thereafter, as shown in FIG. 43, a molybdenum (Mo) film is formed on the 
entire surface in a thickness of 200 nm using the sputtering technique. 
Then, a photosensitive resin (not shown) is formed on the molybdenum film. 
Thereafter, the molybdenum film is subject to the etching treatment so as 
to pattern the source electrode 105, the drain electrode 106 and the data 
electrode 81 connected to the source electrode 105 at the some time. 
The etching treatment of the molybdenum film is performed by a wet etching 
using an etchant comprising phosphoric acid (H.sub.3 PO.sub.4) and nitric 
acid (HNO.sub.3) and acetic acid (CH.sub.3 COOH). The liquid temperature 
of the etchant is set to range from 25.degree. C. to 26.degree. C. 
Further, the semiconductor layer 104 containing the impurity ions is 
subject to the etching treatment using the photosensitive resin as an 
etching mask. The etching is performed using the RIE system, and it is the 
etching condition that the semiconductor layer 103 serving as a base 
substrate is not deteriorated. 
A mixture gas of carbon tetrafluoride (CF.sub.4) and oxygen (O.sub.2) is 
employed as an etching gas. The flow rate of carbon tetrafluoride 
(CF.sub.4) ranges from 80 to 120 sccm, and the flow rate of oxygen ranges 
from 10 to 15 sccm at a pressure ranging from 10 to 12.times.10.sup.-2 
torr with power ranging from 0.05 to 0.1 kW/cm.sup.2. 
Thereafter, an indium tin oxide (ITO) film as the transparent conductive 
film is formed on the entire surface in a film thickness of 100 nm using 
the sputtering technique. Then, a photosensitive resin (not shown) is 
formed on the indium tin oxide (ITO) film. 
Thereafter the indium tin oxide film is subject to the etching treatment so 
as to be connected to the drain electrode 106 and the display electrode 7 
is patterned on the overlapping portion 122 as a part of the anode oxide 
electrode 5. Further, the connecting electrode 8 and the input part (not 
shown) connected to the first data electrode 81 are patterned on the anode 
oxide electrode 5 connected to the gate electrode 101. 
The etching of the indium tin oxide film is performed by wet etching using 
an etchant of the aqueous solution of hydrogen bromine (HBr). The liquid 
temperature of the etchant at this time is set to be 25.degree. C. to 
30.degree. C. 
Then, as shown in FIG. 44, the photosensitive resin 125 for covering the 
first data electrode 81 and the periphery of the gate electrode 101 is 
formed to remove the etching removal part 121 between the overlapping 
portion 122 of the display electrode 7 in the anode oxide electrode 5 and 
the gate electrode 101, or the etching removal part 121 between the 
display electrode 7 and the display electrode 7 by the etching treatment. 
Since the etching removal part 121 in the anode oxide electrode 5 is 
exposed from the photosensitive resin 125 and the display electrode 7 made 
of the indium tin oxide film, the etching removal part 121 is removed by 
the etching treatment using the photosensitive resin 125 and the display 
electrode 7 as an etching mask by the RIE system. 
As etching condition, a mixture gas of sulfur hexafluoride (SF.sub.6) and 
oxygen (O.sub.2) is employed as an etching gas. The flow rate of sulfur 
hexafluoride ranges from 100 to 200 sccm, and the flow rate of oxygen 
ranges from 10 to 40 sccm at a pressure ranging from 4 to 
12.times.10.sup.-2 torr with power ranging from 0.2 to 0.5 kW/cm.sup.2. 
Under the etching condition set forth above, the indium tin oxide film is 
barely etched, and only the tantalum film 2 and the tantalum oxide film 
which is the gate insulating film 102 are etched. 
With the above steps, the anode oxide electrode 5 can be separated into the 
gate electrode 101 and the overlapping portion 122 at the lower part of 
the display electrode 7 as shown in FIGS. 39 and 40 of this embodiment. 
With the employment of the manufacturing steps, the anode oxide electrode 
is enlarged in width (W1) at the time of anodic oxidation treatment, so 
that the anode oxide film can be formed uniformly in a short time. 
Further, since the width W1 of the anode oxide electrode 5 is enlarged, it 
is possible to prevent the breakage of the gate electrode 101 utilizing a 
part of the anode oxide electrode 5 between the display electrode 7 and 
the gate electrode 101 if there is a breakage within the width W2 of the 
gate electrode 101. 
Modification of the Tenth to Fourteenth Embodiments 
Although the indium tin oxide (ITO) film is employed as the transparent 
conductive film in the aforementioned each embodiment, an oxide compound 
such as indium oxide (In.sub.2 O.sub.3), tin oxide (SnO.sub.2), or zinc 
oxide (ZnO) may be employed. 
Although in each embodiment, tantalum is used as a material of the anode 
oxide electrode 5, aluminum or tantalum or aluminum to which carbon, 
silicone, niobium, nitrogen or phosphorous is added may be used. 
Further, in the tenth to thirteenth embodiment, there has been explained 
the case where the transparent conductive film which is the same as the 
display electrode is employed as the upper electrode, however the upper 
electrode may be made of a material which is different from that of the 
display electrode. 
As the material of the upper electrode, chromium, titanium, tungsten, 
titanium siliside, tungsten siliside or chromium film containing nitrogen 
may be used. 
INDUSTRIAL UTILIZATION 
In the liquid crystal display device which is widely used in various 
electronic devices, particularly, in the liquid crystal display device 
employing nonlinear resistors such as the TFD or TFT which can be 
microprocessed and are effective in the reduction of cost as a switching 
element, the nonlinear resistor layer can be formed uniformly in a short 
time by subjecting the electrode to an anodic oxidation treatment, thereby 
preventing breakage of the electrode subsequently and facilitating the 
inspection. 
It is possible to effectively utilize a remaining portion of the anode 
oxide electrode after it is used in the manner that the remaining portion 
is formed as the connecting electrode with the external circuit, it is 
utilized for the frame as the shading portion, and it is utilized for 
repairing the electrode when there occurs a defect. 
Accordingly, it is possible to realize an improvement of the yield when the 
liquid crystal display device is manufactured, improvement of the display 
quality, spreading for various purposes, and reduction of the cost, 
thereby enhancing the industrial usability.