JPH0468318A - Active matrix substrate - Google Patents

Abstract

PURPOSE:To easily form an inter-layer insulating film in a fine shape and to eliminate a defect in insulation between a signal line and a pixel electrode by forming the inter-layer insulating film in multi-layered structure of an organic insulating film and an organic insulating film. CONSTITUTION:This active matrix substrate is equipped with the inter-layer insulating film 10 which is formed covering a switching element 13 formed on an insulating substrate 1, a contact hole 12 formed at the part of the inter- layer insulating film 10 on the output terminal of the switching element 13, and the picture element electrode 11 which is connected to the output terminal of the switching element 13 through the contact hole 12 formed on the inter- layer insulating film. The inter-layer insulating film 10 is formed in the multi- layered structure of the organic insulating film 10a of polyimide resin, etc., and the inorganic insulating film 10b of silicon oxide, etc., and the organic insulating film 10a is etched by using the inorganic insulating film 10b as an etching mask, and then the inter-layer insulating film 10 can be patterned in the fine shape. Consequently, the inter-layer insulating film 10 in the fine shape can easily be formed and an insulation defect between a signal line and a picture element electrode is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an active matrix substrate for constructing a matrix type display device in combination with a display medium such as a liquid crystal.

(Prior Art) Active matrix display devices have advantages such as high contrast and no restrictions on the number of picture elements. Therefore, active matrix substrates used in active matrix display devices are being actively researched.

Since active matrix substrates are manufactured through complicated manufacturing processes, they have the drawbacks of low manufacturing yield and high manufacturing cost.

The third partial plan view of a typical active matrix substrate
FIG. 4 shows a sectional view taken along the line IV-rV in FIG. 3. A large number of gate bus lines 3 made of CrS Ta or the like are provided in parallel on an insulating substrate 1 made of glass or the like, and gate electrodes 2 are branched from the gate bus lines 3. The gate bus wiring 3 functions as a scanning line. On the gate electrode 2, a thin film transistor (
13 (hereinafter referred to as "TFTJ") is formed.

The cross-sectional structure of TFTI 3 will be explained with reference to FIG. 5iNx is applied to the entire surface of the insulating substrate 1 covering the gate electrode 2.
A gate insulating film 4 made of (silicon nitride), 5fOx (silicon oxide), or the like is formed. On the gate insulating film 4 above the gate electrode 2, amorphous silicon (hereinafter referred to as ra-SiJ), polycrystalline silicon, CdS e
A semiconductor layer 5 is formed. At one end of the semiconductor layer 5, a source electrode 6 made of Ti, Mo, AI, etc. is formed in an overlapping manner. Further, on the other end of the semiconductor layer 5, a drain electrode 8 similarly made of TI, MOlAl, etc. is formed in an overlapping manner.

At the end of the drain electrode 80 opposite to the semiconductor layer 5, an I
A picture element electrode 11 made of T O (Indiur ATin Oxide) is superimposed. As shown in FIG. 3, the source electrode 6 is connected to a source bus line 7 that intersects the gate bus line 3 with the gate insulating film 4 interposed therebetween. The source bus wiring 7 functions as a signal line.

The source bus wiring 7 is also made of the same metal as the source electrode 6.

(Problems to be Solved by the Invention) In the active matrix substrates shown in FIGS. 3 and 4, poor insulation between the source bus wiring 7 and the picture element electrode 11 tends to occur. This is because the source bus wiring 7 and the picture element electrode 11 are formed on the same gate insulating film 4.

In order to eliminate such insulation defects, as shown in FIG.
A configuration in which 1 is formed is conceivable. In this configuration, the drain electrode 8 and the picture element electrode 11 are connected through a contact hole 12 formed in an interlayer insulating film 10. still,
In the active matrix substrate of FIG. 5, a-Sf doped with P (phosphorus) is used to establish ohmic contact between the semiconductor layer 5 and the source electrode 6 and drain electrode 8.
(hereinafter referred to as "n+ type a-3iJ") contact layer 9.9 is provided. In the configuration shown in FIG. 5, the source bus wiring 7 and the pixel electrode 11 are formed on different layers. , the aforementioned insulation failure does not occur.

Furthermore, in the active matrix substrate having the cross-sectional configuration shown in FIG. 5, the picture element electrode 11, the gate bus wiring 3, and the source bus wiring 7 can be formed in an overlapping manner as shown in FIG. The picture element electrode 1 is formed by eliminating gaps between the element electrode 11 and the gate bus wiring 3 and source bus wiring 7.
There is an advantage that the area of 1 can be increased. When the area of the picture element electrode becomes larger, the aperture ratio of the display screen becomes larger and the image quality is improved.

Furthermore, if the interlayer insulating film 10 is formed of an organic insulating film such as a polyimide film, it is possible to cover the step caused by the TPT 13 or the like and flatten the upper surface of the substrate. When configuring a display device using liquid crystal as a display medium, if the top surface of the substrate is flat,
Further, the alignment film formed thereon is also formed flat, and poor alignment at the stepped portion of the liquid crystal serving as the display medium can be reduced.

There are the following two methods for patterning the interlayer insulating film 10 made of polyimide resin or the like.

■Wet etching method in which a positive resist is applied onto a film such as polyimide, exposed, developed together with the resist using an alkaline developer, and finally the resist is removed ■Buttering the resist onto a film such as polyimide In method (2), in which etching is performed using a dry etching method and the resist is finally peeled off, the polyimide film is etched with a developer, so the development time becomes longer. Therefore, it is not possible to pattern the polyimide film into a fine shape. Also,
According to the dry etching method (2), the etching selectivity between the polyimide film and the resist is low, so it is necessary to thicken the resist film. Cannot be buttered into shape.

Furthermore, when configuring a display device using liquid crystal as a display medium, an alignment film made of polyimide resin is formed on the interlayer insulating film 10 to cover the picture element electrodes 11. When resin is applied, there is also the problem that cracks and film peeling are likely to occur due to swelling of the interlayer insulating film 10.

The present invention is intended to solve these problems, and an object of the present invention is to provide an active matrix substrate having a structure in which a finely shaped interlayer insulating film can be easily formed. Another object of the present invention is to prevent cracks in the interlayer insulating film even when an alignment film is formed on the interlayer insulating film.
An object of the present invention is to provide an active matrix substrate that does not cause film peeling or the like.

(Means for Solving the Problems) An active matrix substrate of the present invention includes an insulating substrate,
A switching element formed on the substrate, an interlayer insulating film formed to cover the switching element, a contact hole formed in a portion of the interlayer insulating film above the output terminal of the switching element, and the interlayer insulating film. an active matrix substrate comprising a pixel electrode formed on the film and connected to the output terminal of the switching element via the contact hole, the interlayer insulating film comprising an organic insulating film and an inorganic insulating film. It has a multi-layered structure, thereby achieving the above object.

(Function) In the active matrix substrate of the present invention, the interlayer insulating film formed on the switching element has a multilayer structure of an organic insulating film such as polyimide resin or acrylic resin and an inorganic insulating film such as silicon oxide or silicon nitride. have. According to this configuration, by etching the organic insulating film using the inorganic insulating film as an etching mask, the interlayer insulating film can be patterned into a fine shape. Also,
Even when a liquid crystal molecular alignment film made of polyimide resin or the like is further formed on top of this, an inorganic insulating film exists between the organic insulating film and the alignment film, so there is no possibility of cracks or peeling of the organic insulating film. Does not occur.

(Example) Examples of the present invention will be described below. FIG. 1 shows a cross-sectional view of one embodiment of the active matrix substrate of this embodiment. A partial plan view of this embodiment is similar to that shown in FIG. The active matrix substrate of this embodiment includes an insulating substrate 1 made of glass or the like, and a TFTI 3 formed on the substrate 1 and functioning as a switching element. A source bus wiring 7 functioning as a signal line is connected to a source electrode 6 functioning as an input terminal of the TFTI 3. An interlayer insulating film 10 is formed over the entire surface of the substrate 1, covering the TFTI 3 and the source bus wiring 7. The interlayer insulating film 10 consists of an organic insulating film 10a and an inorganic insulating film 10b.
It has a layered structure. A contact hole 12 is formed in a portion of the interlayer insulating film 10 on the drain electrode 8 that functions as an output terminal of the TFTI 3. The picture element electrode 11 is formed on the interlayer insulating film 10 and has a contact hole 12.
It is connected to the drain electrode 8 of the TFTI 3 via. Further, the picture element electrode 11 is formed so as to overlap a part of the gate bus wiring 3 and a part of the source bus wiring 7, as shown in FIG.

The manufacturing process of the active matrix substrate of FIG. 1 is shown in FIGS. 2<a> to 2(c). The manufacturing process of the active matrix substrate of this example will be explained below. First, on an insulating substrate 1 made of glass, a Ta metal layer with a thickness of 3000 mm is formed by sputtering, and this metal layer is patterned by photolithography and etching to form gate bus wiring 3 and gate Electrode 2 was formed. Next, by the plasma CVD method, a gate insulating film 4 made of SiNx with a thickness of 4000 nm, an a-Si layer with a thickness of 1000 nm that will later become the semiconductor layer 5, and a thickness that will later become the contact layer 9.9 are formed. 400 n1 type a-Si layers were successively formed in this order.

Next, the n9 type a-S, i layer and the a-Si layer were patterned to form a contact layer 9.9 and a semiconductor layer 5. Next, a 2,000-layer Mo metal layer was formed on the entire surface of the substrate by sputtering, and the M
o The metal layer was patterned to form the source electrode 6, drain electrode 8, and source bus wiring 7 (FIG. 2(a)). Through the above steps, TFTI 3 is completed.

Next, polyimide resin was applied to a thickness of 1 μm over the entire surface of the substrate 1 on which the TFTI 3 was formed, to form an organic insulating film 10a. Furthermore, the entire surface of the organic insulating film 10a is coated with a film having a thickness of 1°00 by sputtering.
i was formed. After patterning this 5ioJ,
The SiO2 film on the drain electrode 8 of the TPT 13 is removed,
An inorganic insulating film 10b was formed (FIG. 2(b)).

Next, dry etching was performed using the inorganic insulating film 10b as a mask to form a contact hole 12 in the organic insulating film 10a (FIG. 2(C)). Further, an ITO film was formed on the entire surface of the inorganic insulating film 10b and patterned to form a picture element electrode 11 (FIG. 1). The picture element electrode 11 is connected to T through a contact hole 12 formed in the interlayer insulating film 10.
It is connected to the drain electrode 8 of PT13.

In the active matrix substrate of this embodiment, since the interlayer insulating film 10 has a two-layer structure of the organic insulating film 10a and the inorganic insulating film lOb, during dry etching to form the contact hole 12 in the organic insulating film 10a, The inorganic insulating film 10b can be used as a mask. Therefore, it becomes possible to form the organic insulating film 10a in a fine shape.

Furthermore, when forming an alignment film made of a polyimide film on the active matrix substrate of this embodiment, even if a polyimide resin is applied to form the alignment film, the presence of the inorganic insulating film 10b prevents organic Cracks, film peeling, etc. due to swelling of the insulating film 10a do not occur. Interlayer insulation film 10
Since it has a two-layer structure, the insulation properties of the interlayer insulating film 10 are also improved.

In this example, SiO2 was used for the inorganic insulating film iob, but
In addition, SiN, etc. can also be used. Further, in this embodiment, the organic insulating film was patterned by a dry etching method, but if the organic insulating film is made of polyimide resin, it may be patterned by a wet etching method using an alkaline solution. Furthermore, although polyimide resin was used as the organic insulating film in this embodiment, other organic materials such as acrylic resin may also be used.

Further, in this embodiment, the case where TPT is used as the switching element has been described, but other examples, such as MTM
The present invention can also be applied to active matrix substrates using (Metal-Insulator-Metal) elements, diodes, varistors, and the like.

(Effects of the Invention) In the active matrix substrate of the present invention, since the interlayer insulating film has a multilayer structure of an organic insulating film and an inorganic insulating film, an interlayer insulating film with a fine shape can be easily formed. . Therefore, according to the present invention, it is possible to obtain an active matrix substrate that does not cause insulation defects between signal lines and picture element electrodes. Furthermore, even when an alignment film is applied and formed on the active matrix substrate of the present invention, cracks, film peeling, etc. do not occur in the interlayer insulating film, so that an active matrix substrate can be obtained with a high yield.

Figure 1 is a sectional view of an embodiment of the active matrix substrate of the present invention, and Figures 2 <a> to (c) are views showing the manufacturing process of the active matrix substrate of Figure 1. Figure 3 is a partial plan view of a conventional active matrix substrate, Figure 4 is a cross-sectional view taken along the TV-TV line in Figure 3, and Figure 5 is a partial plan view of a conventional active matrix substrate that reduces insulation defects between picture element electrodes and source bus wiring. FIG. 6 is a sectional view of an improved example of the active matrix substrate, and is a partial plan view of the active matrix substrate shown in FIGS. 5 and 1.

DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2... Gate electrode, 3... Gate bus wiring, 4... Gate insulating film, 5... Semiconductor layer, 6... So:2. i-pole, 7... source bus wiring, 8... drain electrode, 9... contact layer, lO
...Interlayer insulating film, 10a...Organic insulating film, 10b.
...Inorganic insulating film, 11...Picture element electrode, 12...Contact hole, 13...TPT0 or more

Claims (1)

[Claims] 1. An insulating substrate, a switching element formed on the substrate, an interlayer insulating film formed to cover the switching element, and the interlayer insulating film on the output terminal of the switching element. An active matrix substrate comprising a contact hole formed in a portion thereof, and a pixel electrode formed on the interlayer insulating film and connected to the output terminal of the switching element via the contact hole. , an active matrix substrate in which the interlayer insulating film has a multilayer structure of an organic insulating film and an inorganic insulating film.