JPH11249168A - Active matrix substrate and its production, liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flatten interlayer insulating films, etc., of thin-film transistors(TFTs) by constituting >=1 interlayer insulating films within a semiconductor thin film of the fired matter of a coating film of perhydropolysilazane or a compsn. contg. the same. SOLUTION: The first interlayer insulating film 11 consisting of silicon oxide, etc., is formed by a CVD method, etc., on a gate electrode 10. A source electrode 13 is formed by CVD method, etc., via a contact hole 12 formed by subjecting the first interlayer insulating film 11 and a gate insulating film 9 to oxidized film etching on this first interlayer insulating film 11. The source electrode 13 is connected to a source line 2. Next, the perhydropolysilazane or the compsn. contg. the same is applied on the first interlayer insulating film 11 and the source electrode 13. This perhydropolysilazane refers to one kind of inorg. polysilazane and is a coating type coating material which is converted to silica by standby firing. The at least one interlayer insulating film 11 is thus composed of the fired matter of the coating film of such compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active matrix substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a liquid crystal panel using an active matrix substrate, for example, a thin film composed of a semiconductor layer, an insulating layer and a conductive layer is selectively formed on an insulating substrate such as a glass substrate in order. Practical as a liquid crystal display device in which a plurality of screen display areas composed of electrodes and the like are formed, and a liquid crystal is driven by applying a voltage to a pixel portion of the screen display area by a thin film transistor (TFT). Has been

The above-mentioned TFT is, for example, polysilicon (Poly
-Si) or the like and stacked in a predetermined pattern.

Here, a conventional structure of a TFT of an active matrix substrate A 'and a method of forming the same will be briefly described with reference to FIGS.

FIG. 3 is a plan view showing a schematic configuration of one pixel formed on a conventional active matrix substrate A ', and FIG. 4 is a partial sectional view of a liquid crystal panel using the active matrix substrate A'. is there.

In FIG. 3, reference numeral 31 denotes a plurality of gate lines provided in a horizontal direction, and 32 denotes a plurality of source lines (data lines) provided in a vertical direction. At the intersection of the gate line 31 and the source line 32, a transparent conductive film (ITO: Indium Tin O
xide) is provided.
Further, a thin film transistor (T) for turning on / off the application of a voltage to the pixel electrode 33 is included in one pixel of the pixel electrode 33.
FT) 34 are provided.

In FIG. 4, 35 is a glass substrate,
A base insulating film 44 is formed on the glass substrate 35, and a source region 36 and a drain region 37 as components of the TFT 34 and silicon oxide (SiO 2).
_The interlayer insulating film 38 of ₂ ) is formed in a predetermined pattern. The source region 36 and the drain region 37 are formed, for example, on the base insulating film 44 of the glass substrate 35.
It is formed by ion-implanting a polysilicon (p-Si) layer deposited thereon.

Then, a source electrode 39 is formed on the source region 36, and this source electrode 39
2 are connected.

[0009] A drain electrode 40 is formed on the drain region 37, and the drain electrode 40 is connected to the pixel electrode 33.

A gate electrode 41 is formed on the source region 36 and the drain region 37 via an interlayer insulating film 38, and the gate electrode 41 is connected to the gate line 31.

A liquid crystal panel using the active matrix substrate A 'having the above-described structure is a glass substrate having a transparent conductive film (ITO: Indium Tin Oxide, etc.) 42 facing the active matrix substrate A'. 43 are arranged at appropriate intervals, and the active matrix substrate A ′ and the glass substrate 43
A predetermined liquid crystal LC is sealed in the gap between the two.

[0012]

However, in the structure of the conventional active matrix substrate A ', the TF
An ITO film that is stacked above the T portion and becomes a pixel electrode is formed along the protruding shape of the drain current region 37 and the interlayer insulating film 38 formed on the glass substrate 35 earlier.

Therefore, when a liquid crystal panel is manufactured using this active matrix substrate A ', the pixel electrode 33 is formed along a portion where the pixel electrode 33 is not flat, that is, along the surface shape of the drain electrode region 37 and the interlayer insulating film 38 as described above. In the raised portion R, the orientation of the liquid crystal molecules of the enclosed liquid crystal LC is changed, and the pixel electrode 33 is inconsistent with the orientation of the liquid crystal molecules in the flat portion F.

If there is a portion where the orientation of the liquid crystal molecules is not uniform, the aperture ratio of the liquid crystal panel is reduced (for example, the aperture ratio of the conventional liquid crystal panel is about 65%).
%), There is a problem that the screen display becomes dark.

As described above, the main reason why ITO or the like as the pixel electrode 33 cannot be completely flattened in the past is that the interlayer insulating film 38 made of silicon oxide (SiO ₂ ) is formed by the CVD (Chemical Vapor). Deposition: chemical vapor deposition).
In other words, the method of forming the interlayer insulating film 38 by CVD has advantages such as good film quality and good step coverage, but has a convex shape of the drain region 37 due to characteristics such as diffusibility of a reaction gas and a crystal growth rate. In this case, the insulating film 38 is vapor-grown along the raised shape, so that the entire interlayer insulating film 38 cannot be formed flat.

Therefore, a pixel electrode 33 is formed on the interlayer insulating film 38 by sputtering or the like.
The effect of the convex surface shape also appeared on the TO film itself, and a non-flat portion R was eventually formed.

The present invention has been devised in view of the above-mentioned problems, and has as its object to provide an active matrix substrate having a structure in which an interlayer insulating film or the like of a TFT is flattened and a method of manufacturing the same. It is in.

[0018]

In order to achieve the above object, an active matrix substrate according to the present invention has a structure in which pixel electrodes are formed in a matrix on a substrate, and a thin film transistor is formed in connection with each pixel electrode. In the active matrix substrate, at least one of the interlayer insulating films of the semiconductor thin film forming the thin film transistor is made of a fired product of a coating film of perhydropolysilazane or a composition containing the same.

Accordingly, due to the properties of the coating solution of perhydropolysilazane or a composition containing the same (for example, a solution using xylene as a solvent), a drain electrode and the like are formed, and the surface is flat even on the uneven substrate surface. Since a simple coating film can be formed, the surface of an interlayer insulating film or the like formed by a baked product of the coating film can be planarized.

Therefore, if a pixel electrode made of ITO or the like is formed on the flattened interlayer insulating film, the surface of the pixel electrode is also flat, and there is no raised portion unlike the conventional case. Therefore, if a liquid crystal panel is manufactured using this active matrix substrate, the orientation of the molecules of the enclosed liquid crystal can be made uniform, so that the aperture ratio can be increased and the brightness of the screen display can be improved. Can be done.

Further, the fired product of the coating film of perhydropolysilazane or a composition containing the same contains silicon oxide (SiO ₂ ), silicon nitride (SiN) and silicon hydroxide (SiOH) as constituent components. Since it is possible, it can be expected that the etching rate is changed according to the pattern shape or the like by changing the etching characteristics.

By adjusting the ratio of silicon oxide (SiO ₂ ), silicon nitride (SiN) and silicon hydroxide (SiOH), the characteristics (density, refractive index, dielectric constant, etc.) of the insulating film can be adjusted according to the application. ) Can be changed.

Further, a method of manufacturing an active matrix substrate according to the present invention is a method of manufacturing an active matrix substrate in which pixel electrodes are formed in a matrix on a substrate, and thin film transistors are connected to the respective pixel electrodes. At least one interlayer insulating film of the semiconductor thin film forming the thin film transistor may be formed by applying perhydropolysilazane or a composition containing the same to a predetermined thickness; And a firing step of firing a coating film of polysilazane or a composition containing the same.

According to this method, since the interlayer insulating film and the like can be formed by flattening, the pixel electrode made of ITO or the like can be formed flat on the interlayer insulating film by, for example, sputtering. . Therefore, if the active matrix substrate manufactured by this method is applied to a liquid crystal panel, the aperture ratio can be improved and the performance of the liquid crystal panel can be improved.

In the method of manufacturing an active matrix substrate according to the present invention, in the applying step, a solution of perhydropolysilazane or a composition containing the same is dropped on a substrate surface and spin-coated. By spin coating, coating can be performed more easily and an insulating film having a uniform thickness can be formed.

In the firing step, the applied film of perhydropolysilazane formed by the coating step or a composition containing the same is heated to 1 atm, 350 ° C., 180 ° C.
Minutes, more preferably, a pressure of 1 to ² kg / cm ² and a temperature of about 1 to ² kg / cm ² with respect to a coating film of perhydropolysilazane or a composition containing the same formed by the above coating step. Steam annealing at a temperature of 130 ° C. and a baking time of about 180 minutes, or a pressure of about 4 kg / cm ² and a temperature of about 13 for a coating film of perhydropolysilazane or a composition containing the same.
An insulating film can be formed by performing steam annealing at 0 ° C. and a baking time of about 180 minutes.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a plan view showing a schematic configuration of one pixel formed on an active matrix substrate A according to the present embodiment. FIG. 2 is a plan view of a liquid crystal panel using the active matrix substrate A. It is a fragmentary sectional view.

In FIG. 1, reference numeral 1 denotes a plurality of gate lines provided in a horizontal direction, 2 denotes a plurality of source lines (data lines) provided in a vertical direction, and an intersection of the gate line 1 and the source line 2 includes a transparent conductive material. Pixel electrode 3 formed of a film (such as ITO)
Is provided.

One pixel of the pixel electrode 3 is provided with a thin film transistor (TFT) 4 for turning on / off a voltage application to the pixel electrode 3.

In FIG. 2, reference numeral 5 denotes a glass substrate made of quartz glass or the like, on which a semiconductor layer is formed in a predetermined pattern.

That is, on the glass substrate 5, first, the CVD
A base insulating film 6 made of silicon oxide (SiO ₂ ) or the like is formed by a method or the like.

For example, a polysilicon layer (p-Si) is deposited on the base insulating film 6, and a source region 7 and a drain region 8 are formed by ion-implanting a part of the polysilicon layer. Is done. Further, a gate insulating film 9 made of silicon oxide (SiO ₂ ) or the like is formed by a CVD method or the like so as to cover the source region 7 and the drain region 8.

A gate electrode 10 made of a conductive electrode film such as polysilicon is formed on the gate insulating film 9 and connected to the gate line 1.

On the gate electrode 10, a first interlayer insulating film 11 made of silicon oxide (SiO ₂ ) is formed by a CVD method or the like.

Then, on the first interlayer insulating film 11, the first
A source electrode 13 is formed by a CVD method or the like via a contact hole 12 formed by performing an oxide film etching on the interlayer insulating film 11 and the gate insulating film 9. This source electrode 13 is connected to the source line 2.

Next, perhydropolysilazane or a composition containing the same is applied on first interlayer insulating film 11 and source electrode 13.

Here, perhydropolysilazane is a kind of inorganic polysilazane, and is a coating type coating material which is converted into silica by baking in air.

For example, polysilazane manufactured by Tonen Co., Ltd.
- it is soluble in an organic solvent to the base unit (such as xylene) inorganic polymers - _(SiH 2 NH).

This inorganic polymer solution in an organic solvent (for example, a 20% xylene solution) is used as a coating solution, and is calcined in the air to react with moisture and oxygen. A dense high-purity silica (amorphous SiO ₂ ) film approximately equivalent to that described above can be obtained.

In the present embodiment, this perhydropolysilazane was spin-coated (for example, 2000 rpm, 20 seconds) on the first interlayer insulating film 11 and the source electrode 13. At this time, perhydropolysilazane is excellent in step coverage and flattening of the substrate surface, so that the surface of the coating film can be made flat.

Then, the perhydropolysilazane coating film is subjected to steam annealing under the conditions of, for example, 1 atmosphere, 350 ° C., and 180 minutes, so that the surface is flattened and the second interlayer insulating film having a thickness of about 1.7 μm is formed. 14 can be obtained.

The annealing conditions are not limited to the above. For example, the coating film of perhydropolysilazane is fired under the conditions of pressure: 1 to ² kg / cm ² , temperature: 130 ° C., and firing time: 180 minutes. You may make it.

The conversion of perhydropolysilazane to silica when such steam annealing is performed is represented by the following formula [1].

[0045]

Embedded image

As can be seen from this chemical reaction formula, the second interlayer insulating film 14 as a fired film obtained by subjecting the coating film of perhydropolysilazane to steam annealing is a residue (silicon oxide (SiO ₂ )) Silicon nitride (SiN) and silicon hydroxide (SiOH) are also included as unconverted products.

The SiO ₂ containing SiN or SiOH is
It is considered that the smaller the content of SiN and SiOH is, the better the content of SiN and SiOH is. By changing the reaction conditions, the residual amounts of SiN and SiOH can be appropriately controlled to positively contain SiN and SiOH in SiO ₂ .

Then, on the second interlayer insulating film 14, via a contact hole 15 formed by etching the second interlayer insulating film 14, the first interlayer insulating film 11 and the gate insulating film 9 with an oxide film. The pixel electrode 3 made of ITO is formed by a vacuum evaporation method, sputtering, or the like.

At this time, since the second interlayer insulating film 14 on which the pixel electrode 3 is formed is manufactured by a novel forming method of baking the coating film of perhydropolysilazane as described above, the gate insulating film is formed. 9 and the step of the raised portion in the first interlayer insulating film 11 can be flattened.
The surface of the interlayer insulating film 14 is in an extremely flat state.
Therefore, the pixel electrode 3 on the surface of the second interlayer insulating film 14
Can also be formed in a flattened state without ridges.

The above is an example of the configuration of the active matrix substrate A according to the present embodiment and an example of the manufacturing method.

In order to form a liquid crystal panel P using the active matrix substrate A according to this embodiment,
As shown in FIG. 2, a glass substrate 43 having a transparent conductive film (ITO) 42 is disposed at an appropriate distance from the active matrix substrate A, and the active matrix substrate A and the glass substrate 43 A predetermined liquid crystal LC is sealed in the gap between the two.

In the liquid crystal panel P thus configured, since the surface of the second interlayer insulating film 14 and the surface of the pixel electrode 3 are flattened as described above, the alignment of the liquid crystal molecules is uniform. (See FIG. 2).

As a result, in the liquid crystal panel P using the active matrix A according to the present embodiment, the aperture ratio can be increased from about 65% to about 71%, and the screen display can be brightened.

The second interlayer insulating film 14 as a fired film obtained by subjecting the perhydropolysilazane coating film to steam annealing is made of silicon oxide (SiO ₂ ), silicon nitride (S
In the case where iN) and silicon hydroxide (SiOH) are included as constituents, it is expected that the etching rate is changed according to the pattern shape by changing the etching characteristics.

Further, by adjusting the ratio of silicon oxide (SiO ₂ ), silicon nitride (SiN) and silicon hydroxide (SiOH), the characteristics (density, refractive index, dielectric constant, etc.) of the insulating film can be adjusted according to the application. ) Can be changed.

Further, by forming an insulating film using a material in a liquid phase as in the present application, a pixel electrode can be formed on a flat inter-phase insulating film. In particular, in the case of a reflective liquid crystal panel, a pixel electrode can be formed with almost no space on an insulating film, so that an aperture ratio is high,
In addition, a bright display can be obtained because the reflection area increases.

[0057]

As described above, the active matrix substrate according to the present invention is a thin film transistor in which pixel electrodes are formed in a matrix on the substrate and semiconductor thin films are laminated in a predetermined pattern corresponding to each pixel electrode. An active matrix substrate formed with
At least one interlayer insulating film of the semiconductor thin film forming the thin film transistor is formed of a fired product of a coating film of perhydropolysilazane or a composition containing the same, and thus formed of a fired product of the coating film. There is an effect that the surface of the interlayer insulating film or the like can be flattened, and the surface of the pixel electrode can be flattened.

If a liquid crystal panel is manufactured using this active matrix substrate, the orientation of the enclosed liquid crystal molecules can be made uniform, so that the aperture ratio can be increased and the brightness of the screen display can be increased. There is an effect that it can be improved.

In the method of manufacturing an active matrix substrate according to the present invention, a thin film transistor in which pixel electrodes are formed in a matrix on the substrate and semiconductor thin films are laminated in a predetermined pattern corresponding to each pixel electrode is formed. A method of manufacturing an active matrix substrate, comprising: applying at least one interlayer insulating film of a semiconductor thin film forming the thin film transistor to perforated polysilazane or a composition containing the same to a predetermined thickness; and Baking the applied film of perhydropolysilazane or a composition containing the perhydropolysilazane formed by the above-mentioned coating step,
An interlayer insulating film or the like can be formed flat. Therefore, a pixel electrode made of ITO or the like can be formed flat on the interlayer insulating film by, for example, sputtering or the like. If the active matrix substrate manufactured by this method is applied to a liquid crystal panel, the aperture ratio can be improved. ,
This has the effect of contributing to higher performance of the liquid crystal panel.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of an active matrix substrate according to the present invention.

FIG. 2 is a partial cross-sectional view showing one embodiment of a liquid crystal panel using the active matrix substrate according to the present invention.

FIG. 3 is a plan view showing a configuration example of a conventional active matrix substrate.

FIG. 4 is a partial cross-sectional view showing a configuration example of a liquid crystal panel using a conventional active matrix substrate.

[Explanation of symbols]

A active matrix substrate 1 gate line 2 source line 3 pixel electrode 4 TFT (thin film transistor) 5 glass substrate 6 base insulating film 7 source region 8 drain region 9 gate insulating film 10 gate electrode 11 first interlayer insulating film 12 contact hole 13 source electrode Reference Signs List 14 Second interlayer insulating film (a fired film obtained by subjecting a perhydropolysilazane coating film to steam annealing) 15 Contact hole P Liquid crystal panel LC liquid crystal A 'Active matrix substrate 31 Gate line 32 Source line 33 Pixel electrode 34 TFT 35 Glass substrate 36 Source region 37 Drain region 38 Interlayer insulating film 39 Source electrode 40 Drain electrode 41 Gate electrode 42 Transparent conductive film (ITO) 43 Glass substrate 44 Base insulating film

Claims (8)

[Claims] 1. An active matrix substrate in which pixel electrodes are formed in a matrix on a substrate, and a thin film transistor is formed in connection with each pixel electrode, wherein at least one of the semiconductor thin films forming the thin film transistor is provided. An active matrix substrate, wherein one interlayer insulating film is made of a baked product of a coating film of perhydropolysilazane or a composition containing the same. 2. A fired product of a coating film of the perhydropolysilazane or a composition containing the same is made of silicon oxide (Si).
_2. The active matrix substrate according to claim 1, comprising O ₂ ), silicon nitride (SiN), and silicon hydroxide (SiOH) as constituent components. 3. The active matrix substrate according to claim 1, wherein the substrate is disposed, and a liquid crystal is sealed in a gap between the active matrix substrate and the substrate. LCD panel. 4. A method for manufacturing an active matrix substrate, wherein pixel electrodes are formed in a matrix on a substrate, and a thin film transistor is formed in connection with each pixel electrode. At least one interlayer insulating film is formed by applying perhydropolysilazane or a composition containing the same to a predetermined thickness, and baking the applied film of perhydropolysilazane or a composition containing the same formed by the above-mentioned application step. And a sintering step. 5. The method according to claim 4, wherein in the applying step, a solution of perhydropolysilazane or a composition containing the same is dropped onto the surface of the substrate to perform spin coating.
A method for manufacturing the active matrix substrate according to the above. 6. The baking step comprises subjecting a coating film of perhydropolysilazane or a composition containing the same formed by the coating step to steam annealing at 1 atm, 350 ° C., and 180 minutes. The method for manufacturing an active matrix substrate according to claim 4, wherein: 7. The sintering step comprises applying a pressure of 1 to ² kg / cm ² , a temperature of approximately 130 ° C., and a sintering time to the applied film of perhydropolysilazane or a composition containing the same formed by the applying step. 6. The method for manufacturing an active matrix substrate according to claim 4, wherein steam annealing is performed under a condition of about 180 minutes. 8. The baking step comprises applying a pressure of about 4 kg / cm ² , a temperature of about 130 ° C., and a baking time to the applied film of perhydropolysilazane or a composition containing the same formed in the applying step. 6. The method for manufacturing an active matrix substrate according to claim 4, wherein steam annealing is performed under a condition of about 180 minutes.