JPS5845028B2 - Matrix type liquid crystal display device - Google Patents

Description

Detailed Description of the Invention The present invention provides a multi-IJ using a thin film transistor (hereinafter referred to as TPT) using tellurium (Te) as a semiconductor layer.
In Lux liquid crystal display devices, the surface of the TPT is coated with aluminum oxide (A120) to protect it from the liquid crystal.
3) and has an affinity for the Te semiconductor layer.
This invention relates to a liquid crystal display device in which the TPT is protected from the liquid crystal with a protective insulating film (Alp3 film) by utilizing the characteristics of the 71-203 film to maintain good element characteristics of the TPT.

First, TPT will be briefly explained with reference to FIG.

TPT has a gate electrode 2 on the surface of an insulating substrate 1 made of glass or the like.
An insulating layer 3 is provided to cover the gate electrode 2, and a semiconductor layer 4, a source electrode 5, and a drain electrode 6 are formed on the insulating layer 3.
It has a structure in which the following steps are sequentially provided.

The materials for the gate electrode 2 include aluminum (A) and gold (A).
Materials such as Au), tantalum (Ta), and indium (In) are used, and they are installed using mask vapor deposition or photoetching techniques.

The material for the insulating film 3 is aluminum oxide (A1203
), silicon dioxide (S i02 ), -silicon oxide (S
In), calcium fluoride (CaF 2 ), etc. can be used, and it is installed to cover the gate electrode 2 by a method such as a vacuum evaporation method, a sputtering method, or a CVD method.

When the gate electrode 2 is made of aluminum (Al 2 ), it is also possible to form an aluminum oxide (A1203) insulating film by anodizing this aluminum.

Cadmium selenide (CdSe), cadmium sulfide (CdS), or the like is generally used as the material for the semiconductor layer 4, and is deposited by a method such as vacuum evaporation or sputtering.

The materials used for the source electrode 5 and the drain electrode 6 are limited to materials that come into ohmic contact with the semiconductor layer 4, but gold (Au), aluminum (AO, etc.) are generally used.

The structure of the TPT is not limited to that shown in FIG. 11, but as shown in FIG. 2, a semiconductor layer 4, a source electrode 5,
The position of the drain electrode 6 may be reversed, or the source electrode 5 and the drain electrode 6 may be placed on the insulating substrate 1, and the semiconductor layer 4 may be placed between the two electrodes, as shown in FIG. The insulating layer 3 and the gate electrode 2 may be provided, or the semiconductor layer 4 may be partially covered with a source electrode 5 and a drain electrode 6, and the insulating film 3 and the gate electrode may be provided thereon, as shown in FIG. You can.

These TPTs using tellurium (Te) for the semiconductor layer 4 were invented by the same inventor as the present application,
This application has been filed by the same applicant as the present application (filed on August 30, 1972, Japanese Patent Application No. 105552/1972), but when TPT using tellurium (Te:) is applied to a matrix type liquid crystal display device, the following results can be obtained. There are advantages such as:

■ Since tellurium (Te) has no photoelectric properties, there is no need to provide a light blocking film.

■ Tellurium (Te) has excellent stability and reproducibility because it consists of a single element.

■ There is no need to heat the substrate when depositing tellurium (Te).

The semiconductor layer used in the present invention is made of tellurium (Te).
A multi-IJ luxury liquid crystal display device using PT will be explained with reference to FIGS. 5 and 6.

A matrix type liquid crystal display device includes a substrate 1 comprising a plurality of gate lines 7 and a plurality of source lines 8 orthogonal to these gate lines, with a TFT array 9 formed at each intersection thereof.
has.

A counter substrate 11 on which a transparent conductive film 10 is formed is located at a position facing this substrate 1, and a liquid crystal material 12 is sandwiched between both substrates.

By the way, TPT using tellurium (Te) for the semiconductor layer 4
If the liquid crystal comes into direct contact with the liquid crystal, its characteristics will deteriorate compared to before the contact.

A specific example will be explained using the TPT having the structure shown in FIG. 1, together with the results shown in FIG.

The substrate 1 is made of transparent glass, the gate electrode 2 is made of aluminum (Al), the insulating film 3 is an aluminum oxide (A1203) film obtained by anodizing the aluminum, the semiconductor layer 4 is made of tellurium (Te), and the source electrode 5 is made of aluminum (A1203). , gold (Au) is used for the drain electrode 6.

The thickness of each gate electrode 2 is 500 to 500.
0 people, the thickness of the insulating film 3 is ioo~1500 people, the tellurium (Te) of the semiconductor layer 4 is 50~500 people, the thickness of the gold (Au) of the source electrode 5 and drain electrode 6 is 250~5000 people,
Also, the gap between the source electrode 5 and the drain electrode 6 is 1 to 100
Approximately μm is appropriate.

Voltage between source and drain electrodes V 10 v, Ge S
If the resistance value between the source and drain when the voltage is 14V is R8,, and the resistance value between the source and drain when V6=OV is R6ff, then TET is Before contacting the liquid crystal, R8, ”-, 30Ω.

Ro(('F 6 M Q with R6ff/RonE200
(Figure T a), but after contact with crystal i, R6nL
, 17 is A2, RoH'', 170 is Q (Fig. 7b), and Roff/Roo becomes 10.

When applying TPT to a matrix type liquid crystal display device as shown in Fig. 6, the value of R6ff/Ron needs to be quite large (Rof f / Ron ≧ 100), but if Rof / Ron is about 10. It cannot be used practically if it is depressed.

In view of the above drawbacks, the present invention provides an insulating film on the surface of the TPT to prevent deterioration of the TFT due to liquid crystal.

FIG. 8 is a sectional view showing an embodiment of the present invention, and 13 is a TPT.
This is an insulating film that protects the LCD from the liquid crystal.

A liquid crystal display device is stolen by sealing a liquid crystal material 12 between a counter substrate 11 on which a transparent conductive film is formed and a substrate 1 on which a TPT is formed, and the TPT on the substrate 1 is isolated from the liquid crystal material 12 by an insulating film 13. ing.

It is expected that by being covered with the insulating film 13, the TPT will not be affected by the deterioration effect from the liquid crystal material and that good device characteristics will be maintained.

However, the insulating film 13 must be made of a suitable material and deposited under suitable conditions.

If an unsuitable material is used, or if a suitable material is deposited under unsuitable conditions, the properties of the TPT will be much worse than before the insulating film is deposited.

Table 1 shows the results of one experiment on the TPT protective film.

As is clear from this table, silicon dioxide (S r 02
), the performance of TPT deteriorates, and silicon oxide (S13N4), -silicon oxide (Si
Even when using n), the performance of TPT deteriorates depending on the deposition method.

However, in particular, TP using tellurium (Te) in the semiconductor layer
In the case of T, even if the surface of the TET is covered with an aluminum oxide (A1203) film by vapor deposition or sputtering, there is no change in the characteristics of the TPT.

The conditions for vapor deposition are that the degree of vacuum is 10-4 torr or more, and the substrate temperature during vapor deposition is from room temperature to about 150°C.

The present invention is based on such experimental results and establishes a protective structure for TPT using Te as a semiconductor layer.
If the TPT is covered with an aluminum oxide (A1203) film and isolated from the liquid crystal, the characteristics of the TPT will not change compared to the characteristics before the liquid crystal is sandwiched.

The present invention takes advantage of the above-mentioned advantages obtained by using TPT having Te as a semiconductor layer in a matrix type liquid crystal display device, and at the same time utilizes the above-mentioned advantages obtained by using TPT having Te as a semiconductor layer.
As a means of preventing this, an Al2O3 film that is substantially effective for TPT using Te was found, and this was used as an isolating protective film for the grade crystal material 12. It has characteristics in that.

As described above, according to the present invention, tellurium (Te) is used in the semiconductor layer.
TPT using this method can be effectively used in matrix type liquid crystal display devices.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the TPT used in the present invention, Figures 2 to 4 are cross-sectional views showing other embodiments of the TPT, and Figure 5 is a cross-sectional view of the TPT used in the present invention.
- A plan view of the main part of an IJTS type aperture crystal display device, Fig. 6 is a sectional view of the main part, and Fig. 7 is a diagram showing the deterioration of TPT, where a is before contact with the liquid crystal, b is after contact with the liquid crystal, FIG. 8 is a partial sectional view showing an embodiment of the present invention. 1...Substrate, 2...Semiconductor layer, 9...
...TFT array, 10...transparent conductive film,
11...Counter substrate, 12...Liquid crystal material, 13...Aluminum oxide film.

Claims (1)

[Claims] 1. A substrate including a plurality of gate lines and a plurality of source lines orthogonal to the gate lines, on which a transistor array consisting of thin film transistors using tellurium as a semiconductor layer is formed at each intersection thereof, and a counter substrate on which a transparent conductor is formed. A matrix type liquid crystal display device comprising a substrate and having a structure in which a liquid crystal material is sandwiched between the transistor array and the transparent conductor, wherein the surface of the thin film transistor is coated with an Al2O3 film. .