JPH0519297A - Liquid crystal panel, liquid crystal display device and production thereof - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display panel which is free from deviation in patterns and has the largest possible effective display area by executing the patterning of light shielding films and semiconductors 4, active layers by self-matching. CONSTITUTION:Insulating films 3, gate electrode gate insulating films 5, and the semiconductor active layers 6, 7 are provided on the light shielding films 2. The semiconductor active layers 6, 7 are exposed over the entire surface from the glass substrate 1 side and are patterned in a self-matching manner by the light shielding films 2 at the time of patterning the semiconductor active layers 6, 7 by a photoresist 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel, a liquid crystal display device and a manufacturing method thereof, and more particularly to a liquid crystal display panel and a liquid crystal display device in which a semiconductor active layer of a thin film transistor and a light shielding part are aligned with each other. It relates to a manufacturing method.

[0002]

2. Description of the Related Art FIG. 3 is a schematic view of a conventional active matrix liquid crystal display device (LCD) using an inverted stagger type thin film transistor (TFT). The TFT has a semiconductor Si active layer 6 on a gate electrode 4, and is formed by connecting a source / drain metal 9 through a contact layer 7 of the same semiconductor Si. This TFT section is an ineffective section for display. Moreover, when the semiconductor Si active layer 6 and the contact layer 7 constituting the TFT are irradiated with light, electron-hole pairs are generated by photoexcitation, and as a result, the off current (leakage current) of the TFT is increased and the contrast is lowered. Occurs. Light-shielding film (usually metal layer) 2 to eliminate the above-mentioned drawbacks
The method of shielding the light from the outside by taking 1, 22, 23 is adopted. Here, the provision of the light shielding film 21 or 22 is effective for the backlight irradiation from the glass substrate 1 side, and the provision of the light shielding film 23 is effective for the backlight irradiation from the glass substrate 15 side.

[0003]

This conventional light-shielding film needs to be provided on the outside so as to wrap at least the semiconductor Si layer. However, if the margin in this pattern layout is too large, the effective area of the display unit becomes small and the luminance characteristics deteriorate. On the other hand, if the margin is too strict, there is a problem that the semiconductor Si layer is irradiated with light due to the pattern shift and the off current increases.

Further, if the patterning of the light-shielding film and the patterning of the semiconductor active layer are performed by a photolithography process using separate masks, the cost increases due to the increase in the number of masks, the manufacturing time increases due to the increase in the processes, and the yield decreases. There was a problem of inviting.

[0005]

According to the present invention, in a liquid crystal display panel having a thin film transistor for driving a pixel on a transparent substrate, a liquid crystal in which a semiconductor active layer and a light shielding film in the thin film transistor are aligned and overlapped with each other. A display panel and a liquid crystal display device can be obtained.

When a liquid crystal display device is used, if the light blocking film does not sufficiently block light and the semiconductor active layer is irradiated with light, off current may increase. In order to prevent these, it is necessary to shield the semiconductor active layer from light. Further, it is desirable that the area of the light shielding film is as small as possible and the effective display area of the liquid crystal display device is as large as possible.

Further, according to the manufacturing method of the present invention, a step of selectively forming a light shielding film on one main surface of the transparent substrate and a step of forming a gate electrode on a portion of the light shielding film included in the light shielding film. A step of forming a transparent insulating film on the gate electrode, a step of forming a semiconductor active layer on the transparent insulating film, a step of forming a photoresist on the semiconductor active layer, and from the other main surface of the transparent substrate. Irradiation, the step of exposing the photoresist using the light-shielding film as a mask, the step of removing the photoresist in the exposed portion of the photoresist and the semiconductor active layer, the step of removing the photoresist other than the exposed portion, and then A liquid crystal display panel or liquid crystal display device including a step of selectively forming a source, a drain and a display electrode can be obtained.

It is preferable to form an insulating film between the light shielding film and the gate electrode. Further, it is preferable that the semiconductor active layer is further provided with a layer having a high impurity concentration at the source / drain electrode extraction portion.

Furthermore, according to the manufacturing method of the present invention, the step of selectively forming a gate electrode on one main surface of the transparent substrate, the step of forming a transparent insulating film on the gate electrode, and the transparent insulating film A step of forming a semiconductor active layer thereon, a step of forming a light-shielding film on the other main surface of the transparent substrate, a step of forming a photoresist on the semiconductor active layer and the light-shielding film, and on one photoresist. Of irradiating both photoresists through a mask to the photoresist, a step of removing the photoresist, the semiconductor active layer and the light-shielding film in the exposed area of the photoresist, and a step of removing the photoresist except the exposed area. Then, a liquid crystal display panel or liquid crystal display device including a step of selectively forming a source, a drain and a display electrode after that is obtained.

[0010]

The present invention will be described below with reference to the drawings. FIG. 1 shows a first method of manufacturing a liquid crystal display device according to the present invention.
FIG. 6 is a schematic process diagram showing the example of FIG.

First, the light shielding film 2 made of Cr on the glass substrate 1
Then, an insulating film 3 such as a silicon nitride film or a silicon oxide film is formed on the entire surface (FIG. 1A).

Next, a gate metal formation patterning 4 is performed, and further, a gate insulating film 5, an amorphous Si film 6, and a high concentration n.
A type impurity-doped (n ⁺ ) amorphous Si film 7 is sequentially formed.
Next, a positive type photosensitive resin (photoresist) 8 is applied and exposed to light. At this time, light is irradiated from the back surface without using a mask, and exposure is performed by self-alignment by the light shielding film 22. Thus, the photoresist 8 other than the portion aligned with the light shielding film 2 is removed (FIG. 1B).

Next, the Si films 6 and 7 are etched and the photoresist 8 is removed to obtain the structure of FIG. 1C. As a result, the semiconductor active layers 6 and 7 are aligned with the light shielding film 2.

FIG. 2 is a process schematic diagram showing a second embodiment of the manufacturing method according to the present invention.

A gate film is formed and patterned 4 on the glass substrate 1, and then the gate insulating film 5, the amorphous Si film 6,
The n ⁺ amorphous Si film 7 is sequentially formed (FIG. 2A).

Next, a metal film 21 serving as a light shielding portion is formed on the back surface, and a photoresist film 8 is applied to the front surface and the back surface (see FIG. 2).
B), exposing through a mask (not shown in the figure). The exposure may be performed from either the front surface or the back surface.

After that, the semiconductor active layers 6 and 7 are etched by using the photoresist film 8 in which only the mask portion has been exposed as a mask to obtain the structure shown in FIG. 2C. The patterned light-shielding film 22 and the semiconductor active layers 6 and 7 have the same pattern, and the margin for alignment is essentially zero.

In this embodiment, the light shielding film 2 and the gate metal 4 are
Since the glass substrate 1 is sandwiched between and, there is an advantage that the step of growing the insulating film 3 shown in FIG. 1A is unnecessary.

[0019]

As described above, according to the present invention, by aligning the semiconductor active layer of the thin film transistor in the liquid crystal display panel with the light-shielding film, the semiconductor active layer is not irradiated with light and the off current is not increased. It has an effect that the effective display area can be obtained.

Further, the patterning of the semiconductor active portion is performed by the whole surface exposure utilizing the self-alignment by the light shielding film, so that the alignment by the mask is not required, the yield is improved, and the cost is reduced.

[Brief description of drawings]

FIG. 1 is a schematic process diagram showing a first embodiment of a method of manufacturing a liquid crystal display device according to the present invention.

FIG. 2 is a process schematic diagram showing a second embodiment of the method of manufacturing a liquid crystal display device according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional liquid crystal display device.

[Explanation of symbols]

1 glass substrate 2, 21, 22, 23 light-shielding film 3 insulating film 4 gate electrode 5 gate insulating film 6 amorphous Si film 7 n ⁺ amorphous Si 8 photosensitive resin (photoresist) 9 source / drain electrode 10 display Electrode 11 Liquid crystal 12 Alignment film (polyimide film) 13 Counter electrode 14 Color filter 15 Glass substrate

Claims (4)

[Claims] 1. A liquid crystal display panel having a thin film transistor for driving pixels on a transparent substrate, wherein a light shielding film whose position is aligned with a semiconductor active layer of the thin film transistor is formed. 2. A liquid crystal display device comprising the liquid crystal display panel according to claim 1. 3. A step of selectively forming a light shielding film on one main surface of a transparent substrate, a step of forming a gate electrode overlapping the light shielding film, and a transparent insulating film formed on the gate electrode. Step, forming a semiconductor active layer on the transparent insulating film, forming a photoresist on the semiconductor active layer, irradiating from the other main surface of the transparent substrate, using the light shielding film as a mask A step of exposing the photoresist, a step of removing the photoresist and the semiconductor active layer in the exposed portion of the photoresist, a step of removing the photoresist other than the exposed portion, and then a selective source The method for manufacturing a liquid crystal display panel according to claim 1, or the method for manufacturing a liquid crystal display device according to claim 2, further comprising: forming a drain and a display electrode. 4. A step of selectively forming a gate electrode on one main surface of a transparent substrate, a step of forming a transparent insulating film on the gate electrode, and a semiconductor active layer on the transparent insulating film. A step of forming a light-shielding film on the other main surface of the transparent substrate, a step of forming a photoresist on the semiconductor active layer and the light-shielding film, and a mask on one of the photoresists. And irradiate both the photoresists to expose the photoresist, the step of removing the photoresist, the semiconductor active layer and the light-shielding film in the exposed portion of the photoresist, and the photoresist other than the exposed portion. 3. The method for producing a liquid crystal display panel according to claim 1, or the liquid according to claim 2, further comprising the step of: and a step of selectively forming a source, a drain and a display electrode. Of manufacturing a crystal display device.