JP2012252361A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure suppressing electrical interference between a pixel electrode and source wiring, and further the pixel electrode and a TFT.SOLUTION: A display device comprises: a thin-film transistor; a first interlayer insulating film formed on an active layer, a gate insulating film, and a gate electrode of the thin-film transistor; source wiring and a drain electrode formed on the first interlayer insulating film and connected to the active layer; a second interlayer insulating film formed on the source wiring and the drain electrode; a conductive film for electromagnetic shielding formed on the second interlayer insulating film; a third interlayer insulating film formed on the conductive film; and a pixel electrode formed on the third interlayer insulating film and connected to the drain electrode. The conductive film is provided between the source wiring and the pixel electrode.

Description

The invention disclosed in this specification relates to a structure of an active matrix reflective liquid crystal panel.

FIG. 8 shows a schematic cross section of a conventionally known active matrix reflective liquid crystal panel. In the configuration shown in FIG. 8, a source region portion 708, a gate electrode portion 709, and a drain region portion 71.
A TFT (thin film transistor) having a 0 region is disposed, and a reflective pixel electrode 706 is connected to the source region 710 of the TFT.

In general, in such a structure, the flatness of the top surfaces of the source electrode portion 708, the gate electrode portion 709, and the drain electrode portion 710 and the flatness between the pixel region 711 and other regions are as shown in the figure. Not considered much.

The flatness irregularity (that is, unevenness) is usually about 300 nm to 700 nm.

The presence of such irregularities causes the disorder 707 of the liquid crystal molecules. However, when the thickness of the liquid crystal layer is as thick as 7 μm or 8 μm or more, the influence of the unevenness does not have a great influence on the display.

That is, the influence of the disturbance of the liquid crystal molecules does not reach the entire thickness direction of the liquid crystal layer, and the influence on the display is small.

However, in recent years, it has been required to further reduce the thickness of the liquid crystal layer due to the pursuit of high image quality and the accompanying progress in liquid crystal materials.

In particular, in a reflective liquid crystal panel, light passes through the liquid crystal layer twice, so that the thickness is required to be halved compared to a transmissive type. (It's not really a simple story, but it seems to be roughly)

Up to now, reflective liquid crystal panels have not been required to have fine display characteristics and high-speed moving image display. Therefore, it was not necessary to forcibly reduce the thickness of the liquid crystal layer and improve the display characteristics.

According to the knowledge of the present inventors, it has been found that the reflective liquid crystal panel is suitable for use in a projection type projector.

This is because projectors are required to have a small screen size (the optical system becomes expensive when the screen size is large), and the reflective LCD panel is small, such as a screen size of 2.5 inches diagonal or less. This is because the aperture ratio of the pixel can be higher than that of the transmissive type.

In general, when the screen size is reduced, in the transmissive type, the ratio of the area where light is not transmitted, such as TFT, wiring, and capacitive electrode, increases, and the transmission loss of the transmissive portion becomes obvious. (According to the calculations by the applicants, this tendency becomes apparent when the screen size is 2.5 inches or less.)

On the other hand, in the reflective type, TFTs, wirings, and capacitive electrodes can be arranged below the reflective electrode, and the reflective loss of the reflective electrode can be made much smaller than that of the transmissive transmission loss.

A projector is required to have a performance for performing high-definition display. Therefore, high display characteristics are required for the reflective liquid crystal panel used in the projector. In particular, in the case of a projector, the image is magnified several tens to 100 times or more, so this requirement becomes severe.

For this reason, the reflective liquid crystal panel is also required to have high display characteristics, and in order to realize this, the liquid crystal layer is required to be thin.

According to the knowledge of the present applicants, in order to obtain the required display characteristics, in the case of a reflective liquid crystal panel, the thickness of the liquid crystal layer is required to be about 2 to 4 μm. This is required from the condition that maximizes the contrast.

In such a case, when the uneven step on the surface in contact with the liquid crystal layer is 10% or more of the liquid crystal layer,
The disorder of the alignment of the liquid crystal becomes remarkable, and the image quality (particularly, the contrast) is remarkably deteriorated.

The thickness d of the liquid crystal layer is determined by the condition that maximizes the contrast. The condition for maximizing the contrast is determined by the product (Δnd) of Δn (retardation) determined by the liquid crystal material and the thickness d of the liquid crystal layer. However, this value has a wavelength dependency and has a troublesome property that the dependency varies depending on the liquid crystal material, and it is not easy to optimize.

FIG. 7 shows a simulation result assuming a reflective liquid crystal panel. Here, the horizontal axis represents the wavelength of incident light, and the vertical axis represents the ratio between incident light and output light (defined as transmittance).

  Plot points in FIG. 7 are obtained when the thickness of the liquid crystal layer is changed.

The wavelength sensitivity of the human eye is in the range of about 450 nm to 680 nm, and has a maximum value near 550 nm.

Therefore, when color display is to be performed, the curve as shown in FIG.
It is important that the transmittance in the 80 nm range is as flat as possible. In particular, flatness in the range of 500 nm to 600 nm with high wavelength sensitivity is important.

Of course, it is important that the transmittance is as high as possible (that is, the transmission loss is as small as possible).

Considering this point, in the simulation result shown in FIG.
The case of 2.86 μm and 3 μm is preferable. In addition, the thickness of the liquid crystal layer is 2.5 μm, 3.5 μm
In the case of m, it becomes a thing which can be used once.

For example, when the thickness of the liquid crystal layer is 3 μm, the unevenness of the surface in contact with the liquid crystal layer is at least 0.3.
It is required to be not more than μm (300 nm).

In this case, the unevenness of the surface in contact with the liquid crystal layer as shown in FIG. 8 adversely affects the display.

As one method for solving this problem, it is conceivable that a fluid material is used as the interlayer insulating film 712 during film formation to absorb the step.

  However, for this purpose, the interlayer insulating film must be made considerably thick.

When the interlayer insulating film is thickened, the pixel electrode 706 is finally brought into contact with the source electrode, so that the groove is deepened. This causes a contact failure and is not preferable.

In particular, in the case of a small and fine structure having a diagonal dimension of 2.5 inches or less, such as a liquid crystal panel for a projector, the problem of the contact becomes obvious.

Thus, flattening the surface in contact with the liquid crystal also has a balance with other requirements,
It's not easy.

An object of the invention disclosed in this specification is to solve this problem and to provide a structure capable of flattening a surface in contact with a liquid crystal while satisfying other requirements. Also, pixel electrode and source wiring,
It is another object of the present invention to provide a structure that suppresses electrical interference between a pixel electrode and a TFT.

[First invention]
One of the inventions disclosed in this specification is a structure whose manufacturing steps are illustrated in FIGS.
Source wirings 305 and gate wirings 204 (see FIG. 3) arranged in a grid pattern;
A thin film transistor in which a source region 207 is connected to the source wiring 305 and the gate wiring 204 is connected to the gate electrode 202;
A drain electrode 303 formed simultaneously with the source wiring 305 (see FIG. 6);
An auxiliary capacitance electrode 401 formed above the drain electrode 303 (see FIG. 6);
A reflective pixel electrode 602 formed above the auxiliary capacitance electrode 401 (see FIG. 6);
Have
A storage capacitor is formed between the drain electrode 303 and the storage capacitor electrode 401.
(See Figure 6)
The drain electrode 303 occupies most of the pixel region (see FIG. 3).

In the above configuration, the source wiring 305 and the gate wiring 204 have a lattice shape in which linear shapes intersect as shown in the figure. However, the lattice arrangement is not limited to this structure. For example, at least one of the patterns may be bent.

Alternatively, the wiring structure may be a single layer or multiple layers. In the structure shown in FIG. 3, the gate wiring is composed of a single layer of an aluminum film. The gate electrode 202 is formed as a pattern extending from the gate wiring 204.

In the structure shown in FIG. 3, the source wiring 305 is configured by a laminated film of a titanium film 302, an aluminum film 303, and a titanium film 304. In FIG. 3, a portion 305 made of an aluminum material that constitutes the main part of the wiring is illustrated as the source wiring. (The upper and lower titanium films are omitted)

As a structure of the thin film transistor (referred to as TFT), a channel region (under the gate electrode 202) exists between the source region 207 and the drain region 205 (under the contact 308) whose basic structure is shown in FIG. 10) in addition to the basic structure in FIG.
The active layer 11 can be bent as shown in FIG.

Alternatively, a structure in which a plurality of gate electrodes are provided on the active layer 11 as shown in FIG. 10 and a plurality of TFTs are substantially connected in series can be used.

  As the TFT structure, an inverted staggered type can also be used.

In the configuration of the first invention,
[Drain electrode 303 formed simultaneously with source wiring 305] (see FIG. 6)
As representatively shown in FIG. 3, on the same surface (in this case, on the interlayer insulating film 301)
It is obtained by forming a pattern as shown by 303 and 305 by patterning the film formed in (1).

In order to confirm whether or not they are formed at the same time, it can be confirmed by taking an enlarged cross-sectional photograph using an electron microscope.

The drain electrode 303 occupies most of the pixel region (see FIG. 3)
As illustrated in FIG. 3, a region surrounded by the source wiring and the gate wiring is defined as a pixel region,
A structure that occupies at least 50% or more, preferably 70% or more of the region.

Note that since the reflective pixel electrode partially overlaps with the source wiring and the gate wiring, the periphery (edge portion) of the pixel region partially overlaps with the source wiring and the gate wiring.

In the configuration of the first invention, the auxiliary capacitor is formed as a structure in which the silicon nitride film 400 is sandwiched between the drain electrode 303 and the auxiliary capacitor electrode 401 as shown in the lower part of FIG. Yes.

In the structure shown in FIG. 6, the upper side of the auxiliary capacitor is flattened by the polyimide resin film 501.

[Second invention]
Other aspects of the invention are:
Source wiring and gate wiring arranged in a grid,
A thin film transistor in which a source region is connected to the source wiring and the gate wiring is connected to a gate electrode;
A drain electrode formed simultaneously with the source wiring;
An auxiliary capacitance electrode formed above the drain electrode;
A conductive film for electromagnetic shielding formed above the auxiliary capacitance electrode;
A reflective pixel electrode formed above the conductive film;
Have
A storage capacitor is formed between the drain electrode and the storage capacitor electrode,
The drain electrode occupies most of the pixel region.

Here, the conductive film for electromagnetic shielding is a film indicated by 502 in FIG. The conductive film 502 has a structure that covers the entire region other than the contact portion 603 between the pixel electrode 602 and the drain electrode 303.

By doing so, it is possible to suppress electrical interference between the pixel electrode and the source wiring, and further, the pixel electrode and the TFT.

[Third invention]
The other invention is composed of
Source wiring and gate wiring arranged in a grid,
A thin film transistor in which a source region is connected to the source wiring and the gate wiring is connected to a gate electrode;
A drain electrode formed simultaneously with the source wiring;
An auxiliary capacitance electrode formed above the drain electrode via a dielectric film;
A conductive film for electromagnetic shielding formed above the auxiliary capacitance electrode;
A reflective pixel electrode formed above the conductive film;
Have
A storage capacitor is formed between the drain electrode and the storage capacitor electrode,
The drain electrode occupies most of the pixel region,
Flatness of the surface on which the dielectric film is formed is ensured by the gate electrode, the source wiring, and the drain electrode.

In this configuration, in the structure illustrated in FIG. 6, the drain electrode 303 and the source wiring 305 are formed so that the raised portion of the interlayer insulating film 301 caused by the presence of the gate electrode 202 and the upper surface thereof are aligned. Thus, the unevenness of the surface on which the silicon nitride film 400 is formed is corrected, and the remaining unevenness can be absorbed by the resin film 501.

In this case, the thickness of the gate electrode 202 needs to be matched to some extent with the total thickness of the aluminum film 303 and the titanium films formed above and below it.

[Fourth Invention]
Other aspects of the invention are:
Source wiring and gate wiring arranged in a grid,
A thin film transistor in which a source region is connected to the source wiring and the gate wiring is connected to a gate electrode;
A drain electrode formed simultaneously with the source wiring;
An auxiliary capacitance electrode formed above the drain electrode via a dielectric film;
A conductive film for electromagnetic shielding formed above the auxiliary capacitance electrode;
A reflective pixel electrode formed above the conductive film;
Have
A storage capacitor is formed between the drain electrode and the storage capacitor electrode,
The drain electrode occupies most of the pixel region,
The difference in thickness between the gate electrode and the source wiring and drain electrode is 20% or less of the thickness of the liquid crystal layer.

In this configuration, the thickness of the gate electrode 202 (including the thickness of the anodic oxide film in the case of FIG. 6) and the thickness of the drain electrode 303 (the thickness of the upper and lower titanium films in the case of FIG. 6). The difference is 20% or less of the thickness of the liquid crystal layer.

In the structure as illustrated in the lower part of FIG. 6, when the difference in film thickness between the gate electrode 202 and the drain electrode 303 cannot be absorbed by the upper resin film, a step caused by the difference is generated on the surface of the pixel electrode. It is the structure for suppressing that it becomes a level | step difference of this and it becomes the cause of the orientation defect of a liquid-crystal layer.

The value of 20% or less is a value that takes into account the absorption of the unevenness by the resin layer when the step of the unevenness remaining finally is 10% or less. Of course, the smaller the difference in film thickness between the gate electrode and the drain electrode, the better.

In the configuration shown in FIG. 6 (or FIG. 5), all of the source line and the gate line are completely covered with the conductive film 502 for electromagnetic shielding. Further, except for the drain contact portion of the TFT, it is covered with a conductive film 502 for electromagnetic shielding.

With such a configuration, electrical interference between the pixel electrode and the source and drain electrodes can be eliminated. Further, electrical interference between the pixel electrode and the TFT can be eliminated.

By employing the invention disclosed in this specification, a reflective liquid crystal panel having a structure in which a contact can be easily formed and a surface in contact with liquid crystal can be planarized can be provided.

4A and 4B illustrate a manufacturing process of a liquid crystal panel. 4A and 4B illustrate a manufacturing process of a liquid crystal panel. 4A and 4B illustrate a manufacturing process of a liquid crystal panel. 4A and 4B illustrate a manufacturing process of a liquid crystal panel. 4A and 4B illustrate a manufacturing process of a liquid crystal panel. 4A and 4B illustrate a manufacturing process of a liquid crystal panel. The figure which shows the result of having simulated the relationship between the wavelength of the light which permeate | transmits a reflection type liquid crystal panel, and the transmittance | permeability by changing the thickness of a liquid crystal layer. The figure which shows the cross-section of the conventional reflective liquid crystal panel. The figure which shows the example of the apparatus provided with the liquid crystal panel using invention. The figure which shows the variation of the structure of TFT.

In this embodiment, the drain electrode of the TFT is extended below the pixel region so as to show an outline viewed from the upper surface in the upper stage of FIG. 6 and a cross section taken along FF ′ in the lower stage of FIG. An auxiliary capacitance is formed using the pattern, and the presence of the pattern further suppresses the unevenness of the pixel electrode surface.

In the following, schematic manufacturing steps are shown in FIGS. First, as shown in FIG. 1, a region to be an active layer of a TFT is formed. Here, the active layer of the TFT is configured using a crystalline silicon film (thickness 50 nm) obtained by crystallizing an amorphous silicon film.

Here, 101 and 102 are the active layer patterns of TFTs. Here TF
An example in which an N-channel TFT is manufactured as T will be described.

The upper part of FIG. 1 shows the state from the top. Moreover, what is shown in the lower part of FIG. 1 is a cross section cut along AA ′ in the upper part. In the lower part of FIG. 1, a glass substrate (or quartz substrate) is indicated by 100.

After obtaining the state shown in FIG. 1, a silicon oxide film 201 functioning as a gate insulating film is formed as shown in the lower part of FIG. Here, the thickness of the silicon oxide film 201 is 100 nm.

  FIG. 3 is a cross-sectional state diagram in which a cross section taken along B-B ′ in the upper stage is shown in the lower stage.

After the silicon oxide film 201 is formed, a gate electrode 202 is formed with aluminum. The film thickness of the aluminum film constituting this aluminum electrode is 500 nm.

An anodic oxide film 203 is formed on the peripheral surface of the gate electrode by using an anodic oxidation technique.
The film is formed to a thickness of nm. The anodic oxide film 203 has a function of protecting the gate electrode 202 electrically and physically.

The gate electrode 201 is formed as extending from the gate wiring 204 as shown in the upper part of FIG.

When the state shown in the lower part of FIG. 2 is obtained, phosphorus is doped by a plasma doping method, and the source region 207, the channel region 206, and the drain region 207 are formed in a self-aligned manner.

When the doping is completed, laser light irradiation is performed to activate the doped phosphorus and anneal the damage during the doping.

In this way, the state shown in FIG. 2 is obtained. Next, as shown in FIG. 3, a silicon oxide film 3 is used as an interlayer insulating film.
01 is formed to a thickness of 700 nm by plasma CVD.

In the state where the silicon oxide film 301 is formed, the upper portion of the gate electrode 202 has a raised convex shape. The height of this rise is almost the same as the height of the gate electrode (500 nm).

Next, a 50 nm thick titanium film, a 400 nm thick aluminum film, and a 50 nm thick titanium film are stacked by sputtering. And 30 by patterning it
6, 303, 305 patterns are obtained. (Here, only the pattern of the aluminum film is shown, and the description of the upper and lower titanium films is omitted)

Reference numerals 306, 303, and 305 in FIG. 3 denote patterned aluminum films. The titanium film is in contact with the upper and lower sides. For example, a titanium film pattern 302 is formed on the lower surface of the alnium pattern indicated by 303, and a titanium film pattern 304 is formed on the upper surface.

  The reason why the titanium film is used is to make a good contact.

In the upper part of FIG. 3, a pattern made of an aluminum film is shown. (Titanium film not shown)

In FIG. 3, reference numerals 305 and 306 denote source wirings. The source wiring 305 is connected to the TFT source region via the contact portion 307.

The stacked body pattern (drain electrode) of 302, 303, and 304 is connected to the drain region of the TFT through a contact hole 308. As shown in the upper part of FIG. 3, this stacked body pattern has a shape that shows most of the pixel region.

Here, the thickness of the gate electrode 202 is approximately 500 nm. (Thickness varies slightly depending on the growth mode of the anodized film)

The total film thickness of the aluminum patterns 306, 303, and 305 and the titanium films above and below the aluminum pattern is 500 nm.

Accordingly, although some unevenness is formed, in the state shown in the lower part of FIG. 3, no large unevenness (unevenness having a step extending over 100 nm) is formed on the upper surface.

Therefore, even if the liquid crystal layer has a thickness of about 3 μm, a structure that does not reveal the influence of liquid crystal molecule disturbance can be obtained.

When the state shown in FIG. 3 is obtained, a silicon nitride film 400 is formed to a thickness of 50 nm by plasma CVD. (See the lower part of Fig. 4)

The silicon nitride film 400 functions as a storage capacitor dielectric. The reason why the film thickness is reduced to 50 nm is to increase the capacity as much as possible.

Next, a titanium film having a thickness of 100 nm is formed by a sputtering method, and patterned to form an auxiliary capacitance forming electrode 401.

The electrode 401 extends in parallel with the source wirings 305 and 306 as shown in the upper part of FIG.

  Note that the cross section taken along D-D ′ in the upper part of FIG. 4 corresponds to the lower part of FIG. 4.

The electrode 401 and the drain electrode 303 connected to the drain region of the TFT are disposed with a silicon nitride film having a thickness of 50 nm interposed therebetween, and form an auxiliary capacitance.

This auxiliary capacitance is configured with a large area (excluding the region of the contact 308) as indicated by 303 in the upper part of FIG. 3, and since the thickness of the silicon nitride film 400 can be reduced, the required capacitance can be easily obtained. Can be secured.

This is particularly effective when the liquid crystal panel is downsized and the area of each pixel is reduced.

Next, as shown in the lower part of FIG. 5, a film 501 made of polyimide resin is formed. The film thickness is 1 μm on average. In addition to polyimide, materials such as polyamide, polyimide amide, acrylic, and epoxy can be used.

The polyimide film absorbs unevenness on the surface of the silicon nitride film 400 and unevenness due to the presence of the titanium film 401. That is, a polyimide film 501 having a substantially flat surface is formed.

Next, a titanium film is formed and further patterned to obtain a titanium film pattern indicated by 502.

  Note that a cross section taken along E-E ′ in the upper part of FIG. 5 is shown in the lower part of FIG. 5.

In this state, an opening is formed for the contact of the drain region of the TFT.

The titanium film 502 is provided as an electromagnetic shield for preventing the pixel electrode formed thereon from electrically interfering with the source wiring and the TFT.

When the state shown in FIG. 5 is obtained, the polyimide resin film 601 is averaged as shown in the lower part of FIG.
A film is formed to a thickness of 1.5 μm, and contact holes are further formed. Then, the reflective pixel electrode 602 is formed of aluminum.

As the aluminum film constituting the pixel electrode 602, a film formed to a thickness of 2000 mm by a sputtering method is used.

In addition, the cross section cut | disconnected by FF 'in the upper stage of FIG. 6 is shown in the lower stage of FIG.

In this configuration, since the source electrode 303 exists, the contact formed in the portion 603 can be formed relatively easily. That is, it is not necessary to form the opening of the contact 603 of the reflective pixel electrode 602 so deeply, and the contact can be easily formed. (Narrow opening and deep opening cause contact failure)

The pixel electrode is provided so as to partially overlap the edge of the source wiring and the drain wiring arranged in a grid pattern. By doing so, the groove opening ratio can be maximized.

When the state shown in FIG. 6 is obtained, a polyimide film (not shown) is formed to a thickness of 120 nm as an alignment film, and a rubbing process (alignment process) is performed. At this time, since the flatness of the surface of the pixel electrode is maintained, partial alignment failure can be suppressed.

After that, a counter substrate is prepared, and liquid crystal is injected between the counter substrate to manufacture a liquid crystal cell. A reflective liquid crystal panel is thus completed.

Note that although a peripheral circuit for driving the active matrix circuit is not described here, it is preferable that the peripheral drive circuit is also formed on the same substrate using a TFT. Further, the peripheral drive circuit may be constituted by an external circuit of an IC chip.

This embodiment shows an example of a TFT having a structure different from that of the first embodiment. In the TFT shown in this embodiment, the active layer 11 has a gate wiring 1 as shown in FIG.
It intersects at 2 and 3 places, and the gate electrode is arranged at this portion.

  This structure can be regarded as an equivalent of three TFTs connected in series.

In this structure, 15 regions in the active layer are defined as source regions and 16 regions are defined as drain regions.

FIG. 10 shows the source line 13 and the drain electrode 14 formed simultaneously with the source line.

The pattern of the drain electrode 14 is formed so as to occupy most of the pixel electrode. The drain electrode 14 corresponds to the pattern 303 in FIG.

The drain electrode 14 is
(1) Formation of auxiliary capacitance (2) Flattening of pixel electrode (3) Facilitation of pixel electrode contact formation
Has the role.

In the structure shown in FIG. 10, three channels are formed in the active layer 11, and a voltage obtained by dividing a voltage applied between the source wiring and the pixel electrode by 3 is applied to each channel. By doing so, the breakdown voltage of the TFT can be increased.

In this embodiment, an example of a display device using a reflective liquid crystal panel obtained by using the invention will be described.

FIG. 9A shows a portable information processing terminal, which has a communication function using a telephone line.

This electronic device includes an integrated circuit 2006 inside a main body 2001. And T
Reflective active matrix liquid crystal panel 2 in which FT is arranged as a switching element
005, a camera unit 2002 for capturing an image, and an operation switch 2004 are provided.

FIG. 9B illustrates an electronic device called a head mounted display. This apparatus has a function of displaying an image in front of the eyes by wearing a main body 21201 on the head with a band 2103. The image is composed of a reflective active matrix type liquid crystal panel 2102 corresponding to the left and right eyes.

FIG. 9C has a function of displaying map information and various information based on a signal from an artificial satellite. Information from the satellite captured by the antenna 2204 is processed by an electronic circuit provided inside the main body 2201, and necessary information is displayed on the active matrix reflective liquid crystal panel 2202.

The operation of the apparatus is performed by an operation switch 2203. Even in such a device, T
A circuit using FT is used.

FIG. 9D illustrates a mobile phone. This electronic device includes a main body 2301 and an antenna 2.
306, an audio output unit 2302, a liquid crystal panel 2304, operation switches 2305, and an audio input unit 2303.

An electronic device illustrated in FIG. 9E is a portable imaging device called a video camera. This electronic apparatus includes a reflection type liquid crystal panel 2402 attached to an opening / closing member and an operation switch 2404 attached to the opening / closing member.

Further, the main body 2401 includes an image receiving unit 2406, an integrated circuit 2407, an audio input unit 2403, operation switches 2404, and a battery 2405.

The electronic device illustrated in FIG. 9F is a projection liquid crystal display device. This device has a main body 250.
1 includes a light source 2502, a reflective liquid crystal panel 2503, an optical system 2504, and a screen 25.
05 has a function of projecting an image.

Note that the invention disclosed in this specification can be used for flat panel displays other than the case of using liquid crystal. For example, in the case of an EL display, it can be used when the base of the light emitting layer is flattened. It can also be used for EC displays.

That is, the invention disclosed in this specification can be used to realize a structure in which the surface above the pixel region is desired to be flat.

101, 102 Active layer of TFT 100 Glass substrate (or quartz substrate)
201 Gate insulating film 202 Gate electrode (composed of aluminum)
203 Anodized film 204 Gate wiring 301 Interlayer insulating film (silicon oxide film)
302 Drain electrode (titanium film)
303 Drain electrode (aluminum film)
304 Drain electrode (titanium film)
305 Source wiring (source electrode)
306 Source wiring (source electrode)
307 Source contact portion 308 Drain contact portion 400 Silicon nitride film 401 Capacitance forming electrode 501 Interlayer insulating film (polyimide resin film)
502 Shield for electric field shielding (black matrix)
601 Interlayer insulation film (polyimide resin film)
602 Pixel electrode (aluminum film)
603 Pixel contact portion

Claims (1)

Source wiring and gate wiring arranged in a grid,
A thin film transistor in which a source region is connected to the source wiring and the gate wiring is connected to a gate electrode;
A drain electrode formed simultaneously with the source wiring, an auxiliary capacitance electrode formed above the drain electrode,
A reflective pixel electrode formed above the auxiliary capacitance electrode,
A storage capacitor is formed between the drain electrode and the storage capacitor electrode,
The display device, wherein the drain electrode occupies most of a pixel region.

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