JPS6017479A - Electric circuit substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD The present invention relates to electrical circuit boards having thin film transistor (TPT) arrays.

[Prior Art] Conventionally, electric circuit boards have been widely used in display devices and the like. An example of such a display device is a liquid crystal display device. A liquid crystal display device generally has a structure in which a liquid crystal is sandwiched between two substrates. Electrodes and other elements are formed on the liquid crystal side of this substrate, and display is performed by controlling the state of the liquid crystal with these elements.

Electrodes are uniformly formed on the surface of one of the two substrates, and a plurality of electrode cars of small block patterns (pixels) having appropriate shapes are formed on the upper surface of the other substrate. In recent years, a TFT array for switching each pixel has been attached to the surface of the substrate on the pixel electrode side. FIG. 1 C± is a schematic cross-sectional view of a liquid crystal display device having such a TFT array, where S and S' are transparent substrates such as glass, l and 1' are gate electrodes, and 2 and 2 ' is an insulating layer, 3 and 3' are semiconductor layers, 4 and 4' are source electrodes, and 5 and 5'
is a drain electrode, 6 is an insulating and alignment layer, and 7 is a drain electrode.
is a liquid crystal, and 8 is a transparent electrode.

1. A semiconductor with photoconductivity is used. If N is used, it is preferable to stabilize the switching characteristics by avoiding exposure to light as much as possible.

For this purpose, a liquid crystal display device as shown in a schematic cross-sectional view in FIG. 2 is used. That is, in the device shown in FIG. 1, light shielding layers 9 and 9' are further formed at positions corresponding to the semiconductor layers on the insulation and orientation R6 covering the TFT array. Metal is generally used for the light shielding layer.

In the above liquid crystal display devices, inorganic materials such as alumina, metal oxides such as titanium oxide, and silicon compounds such as silicon nitride and silicon dioxide have conventionally been used as the insulating layer. However, in order to cover the TPT, a certain level of film thickness is required, and these thin films of inorganic materials have the disadvantage that as the film thickness increases, film distortion increases and cracks and the like are likely to occur. If a rack occurs like this, the TPT will also be destroyed at the same time, so the T
PT is not protected, resulting in deterioration of characteristics.

Therefore, it has been proposed to use organic materials that do not cause cracks, such as silicone resin, acrylic resin, cyclized polyisoprene, etc., as the insulating layer instead of inorganic materials.

However, the insulating layer made of a thin film of these organic materials does not have sufficient performance as a protective layer and has the disadvantage that the TPT characteristics become unstable.

[Object of the present invention] In view of the above-mentioned prior art, an object of the present invention is to provide an improved electrical circuit board in which a TPT insulating layer can exhibit sufficiently satisfactory performance over a long period of time.

Embodiment of the present invention] FIG. 3 is a schematic cross-sectional view showing a preferred embodiment of the electrical circuit board of the present invention. In the figure, an electrical circuit board is used as a component of a liquid crystal display device.

For example, Si, CdS, CdSe, CdTe, Te, etc. are used as the semiconductor layers 3 and 3' constituting the TPT, and amorphous, polycrystalline, or fine-quality St is particularly preferably used. Amorphous St contains H atoms or halogen atoms (especially F
atoms). The H atom or the /\rogen atom may be contained alone or both may be contained.

The content is preferably 0.01 to 40 at% in total,
More preferably, it is 0.01 to 30 at%.

In this embodiment, the insulating layer covering the TFT array consists of two layers (ie 6a and 6b).

Reference numeral 6a is an inorganic insulating layer, which can be formed using an inorganic material such as a metal oxide such as titanium oxide or alumina, or a silicon compound such as silicon dioxide or silicon nitride by a vapor deposition method, a sputtering method, a CVD method, or the like. The thickness of the inorganic insulating layer should be at least enough to protect the channel portion of the TPT, and preferably 500 to 30 mm.
It is about 00A.

6b is an organic insulating layer. Thermosetting resins, thermoplastic resins, or synthetic rubber-based resins are preferably used as materials for forming the organic insulating layer, but they can be substantially completely cured, and in this state they are substantially transparent to visible light. Any material may be used as long as it is transparent and can be subjected to alignment treatment.

Examples of the thermosetting resin include phenol resin, polyester resin, silicone resin, acrylic resin, and urethane resin. A crosslinking agent is added to these thermosetting resins as necessary.

A polymerizing agent, a sensitizer, etc. may be added. Examples of thermoplastic resins include polycarbonate, polyethylene, and polystyrene.

Also in this case, a stabilizer or the like may be added if necessary.
Examples of synthetic rubber resins include cyclized polyisoprene,
Examples include cyclized polybutadiene. Also in this case, a crosslinking agent, a sensitizer, etc. may be added as necessary.

The organic insulating layer is formed by dissolving a thermosetting resin or a synthetic rubber resin in a solvent and then coating it on the inorganic insulating layer, and applying heat or irradiation of electromagnetic waves such as ultraviolet rays or radiation to the resin either alone or in combination. It is formed by crosslinking, polymerizing, and curing.

When a thermoplastic resin is used, for example, the resin is heated to melt and coated on the inorganic insulating layer, and then cooled.
An organic insulating layer is formed by curing. The thickness of the organic insulating layer is 1, which is also related to the thickness of the inorganic insulating layer,
Preferably, the number is 500 to 3000 people. Note that if the sum of the layer thicknesses of the inorganic insulating layer and the organic insulating layer is too large, it may adversely affect the display, so the layer thickness is determined to be an appropriate layer thickness. The heating temperature is preferably 300° C. or lower when amorphous St is used for the semiconductor layer constituting the TPT. This is because when the temperature reaches 300° C. or higher, the amorphous St layer may be thermally affected and the characteristics of TPT may change or deteriorate.

The light shielding layers 9 and 9' are formed by forming a metal such as At on the organic insulating layer by vapor deposition or the like, and then leaving the metal layer in a desired shape and size by photolithography or the like.

In the above, an example has been shown in which the electrical circuit board of the present invention is used as a component of a liquid crystal display device, but the electrical circuit board of the present invention can be used in other display devices such as EL or EC, and furthermore, in other devices. It can be used as a component.

Examples of the present invention are shown below.

Example 1: Plasma CV was further applied on the surface of the substrate on which the TFT array was formed.
A silicon nitride layer (2000 layers thick) was formed using the D method. Next, on this silicon nitride layer, a cyclized polyisoprene resist (0D manufactured by Tokyo Ohka Co., Ltd.) dissolved in xylene was applied.
UR-110WR: 18 cp) was cured for 2 seconds with a spinner coating tar L high pressure mercury lamp at 300 rpm, and then
Baking was performed at 50'0 for 20 minutes. the result,
A colorless and transparent organic insulating layer with a thickness of about 1 gm was formed. Furthermore, metallic aluminum was deposited on top of the layer and removed by etching other than the required portions to form a light-shielding layer.

Subsequently, an alignment treatment was performed thereon, followed by one normal process to produce a liquid crystal display device.

The thus obtained liquid crystal display device was placed in a high temperature and humid atmosphere (90℃
When the display was operated continuously for 1000 hours at 190% RH, it exhibited good display characteristics during operation.

Example 2: On the surface of the substrate on which the TFT array was formed, silicon dioxide fi (3000 wafer thickness) was entirely formed using a sputtering method.
Next, this substrate was immersed in a 10% toluene solution of urethane resin (Delvo MAX manufactured by Toa Paint Co., Ltd.) at 100 mI.
After being pulled up at a rate of 1/min, it was dried for 20 minutes in an atmosphere at a temperature of 50°C. Subsequently, the urethane resin was cured by irradiation with a high-pressure mercury lamp for 40 minutes. As a result, about 1.5p
A colorless and transparent organic insulating layer having a thickness of m was formed. Furthermore, metallic aluminum was deposited on top of the layer and removed by etching to form a light-shielding layer.

After performing alignment treatment thereon, a liquid crystal display device was produced through normal steps.

When the characteristics of the thus obtained liquid crystal display device were evaluated in the same manner as in Example 1, it showed good display characteristics as in Example 1.

[Effects of the present invention] According to the present invention as described above, by further forming an organic insulating layer on the inorganic insulating layer, TP
In addition to protecting the T and stabilizing its properties, even if cracks occur, which is a drawback of conventional inorganic insulating layers, the presence of the organic insulating layer prevents any negative effects on the device. The occurrence of pinholes is almost completely prevented.
can.

Furthermore, an electrical circuit board having stable performance over a long period of time is provided.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a conventional liquid crystal display device, and FIG. 3 is a cross-sectional view of a liquid crystal display device using an electric circuit board according to the present invention. l: Gate electrode 2: Insulating layer 3: Semiconductor layer 4: Source electrode 5 Nidrain electrode 6: Insulating layer 6a: Inorganic insulating layer 6b: Organic insulating layer 7: Liquid crystal 8: Transparent/bright electrode 9: Light shielding layer S second substrate 2 cars 51 Figure 3 q'

Claims (1)

[Claims] (1) An electrical circuit board having a thin film transistor array on the surface of the substrate, characterized in that the thin film transistor array is covered with an inorganic insulating layer, and the inorganic insulating layer is covered with an organic insulating layer. circuit board.