JPH09197390A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an effective arrangement of light shielding films by providing a display device with thin-film transistors(TFTs) of which output is connected to pixel electrodes, interlayer insulating films which are arranger above these TFTs and are made from resin material and a light shielding film for shielding the light of the TFTs. SOLUTION: A source region 108, channel forming region 107, offset gate region 110 and drain region 111 are formed in a self-matching manner. Next, a silicon oxide film 112 is formed as the first interlayer insulating film. The interlayer insulating film 112 is subjected to formation of contact holes and to formation of source electrodes 113 which come into contact with the source region of the TFTs. Next, the second interlayer insulating film 114 is formed by using a transparent polyimide resin or acrylic resin. Further, the light shielding film of the TFTs and the light shielding film consisting of chromium film in common uses as black matrice are formed and are patterned, to form the light shielding films. In such a case, a resin material having a low specific dielectric constant is selected for the resin material constituting the second interlayer insulating film 114.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD [0001] The invention disclosed in the present specification is:
The present invention relates to a configuration applicable to a flat panel display represented by an active matrix type liquid crystal display device and an EL type display device.

[0002]

2. Description of the Related Art Conventionally, an active matrix type liquid crystal display device has been known as a flat panel display. This has a structure in which a thin film transistor for switching is arranged in each of a large number of pixels arranged in a matrix, and the electric charge which goes in and out of each pixel electrode is controlled by this thin film transistor.

In such a structure, it is necessary to arrange a light shielding means so that light does not enter the thin film transistor arranged in the pixel region.

At present, a metal film is used as the light shielding means from the viewpoint of diffusion of impurities and stability. The light-shielding means of this thin film transistor is generally arranged also as a black matrix for covering the peripheral region around the pixel electrode.

In such a structure, the following problems occur. First, as a first problem, there is a problem that a capacitance is formed between the light shielding film and the thin film transistor, which adversely affects the operation of the thin film transistor.

A second problem is that since the light-shielding film is generally formed on a substrate having irregularities, a sufficient light-shielding function cannot be obtained due to the irregularities.

The problem of the light blocking function can be similarly applied to the black matrix arranged so as to overlap the edge of the pixel.

[0008]

SUMMARY OF THE INVENTION An object of the present invention disclosed in this specification is to solve a problem relating to a light-shielding film for shielding a thin film transistor and provide a structure having a high function as an active matrix type display device. To do.

[0009]

The structure of the invention disclosed in the present specification comprises a thin film transistor whose output is connected to a pixel electrode, an interlayer insulating film made of a resin material and arranged above the thin film transistor, A light shielding film for shielding the thin film transistor arranged on the interlayer insulating film,
It is characterized by having.

According to another aspect of the invention, an interlayer insulating film made of a resin material is formed on the thin film transistor, and a light shielding film for shielding the thin film transistor is formed on the interlayer insulating film made of the resin material. It is characterized by

According to another aspect of the invention, there is provided a plurality of pixel electrodes arranged in a matrix and a black matrix that covers at least a part of an edge region of the pixel electrode, and the black matrix is made of a resin material. Is formed on the inter-layer insulating film.

[0012]

【Example】

[Embodiment 1] FIGS. 1 and 2 show a manufacturing process of a pixel portion of an active matrix type liquid crystal display device shown in this embodiment.

First, as shown in FIG. 1A, a glass substrate 1
A silicon oxide film 102 is formed as a base film on 01 by a plasma CVD method to a thickness of 3000 Å.

Next, an amorphous silicon film (not shown) is formed as a starting film of a thin film semiconductor which later constitutes the active layer of the thin film transistor. Here, an amorphous silicon film (not shown) is formed to a thickness of 500 Å by using the plasma CVD method.

And heat treatment or laser light irradiation,
Alternatively, the amorphous silicon film is crystallized by using a method in which heat treatment and laser light irradiation are combined to obtain a crystalline silicon film (not shown).

Then, the crystalline silicon film (not shown) is patterned to obtain the active layer 103 of the thin film transistor.

Next, as shown in FIG. 1A, the active layer 103 is formed.
Oxide film 104 that covers the gate and functions as a gate insulating film
Is formed to a thickness of 1000 Å by plasma CVD method. In this way, the state shown in FIG.

Next, an aluminum film (not shown) containing scandium in an amount of 0.1% by weight is formed by sputtering to a thickness of 4000 Å. This aluminum film will later form a gate electrode.

After forming the aluminum film, a dense anodic oxide film (not shown) having a thickness of 100 Å is formed on the surface of the aluminum film. This anodic oxidation is carried out by neutralizing an ethylene glycol solution containing 3% tartaric acid with aqueous ammonia as an electrolytic solution and using an aluminum film as an anode in this electrolytic solution.

Further, a resist mask (not shown) is arranged and patterning is performed. By performing this patterning, the gate electrode 105 is formed.

After the gate electrode 105 is formed, anodic oxidation is performed again with a resist mask (not shown) left.
This anodic oxidation is performed by using a 3% oxalic acid aqueous solution as an electrolytic solution.

In this anodic oxidation, the anodic oxidation is selectively performed only on the side surface of the gate electrode 105 because a resist mask (not shown) remains. The anodic oxide film formed in this step has a porous structure.

Thus, the anodic oxide film 106 having a porous film quality is formed on the side surface of the gate electrode 105.

This porous anodic oxide film can be grown to a thickness of about several μm. The growth distance can be controlled by controlling the anodic oxidation time.

Here, the thickness of the anodic oxide film 106 is set to 600.
0 °.

Next, anodic oxidation is performed again by using an ethylene glycol solution containing 3% tartaric acid neutralized with aqueous ammonia as an electrolytic solution. In this anodic oxidation process, since the electrolytic solution penetrates into the porous anodic oxide film 106, a dense anodic oxide film 107 is formed around the gate electrode 105 as indicated by 107.

The dense anodic oxide film 107 has a film thickness of 50.
0 °. The main role of the dense anodic oxide film 107 is to cover the surface of the gate electrode so that hillocks and whiskers do not occur in the subsequent steps.

The gate electrode 105 is also protected so that the gate electrode 105 is not simultaneously etched when the porous anodic oxide film 106 is removed later.

Further, it also has a role of contributing to the formation of an offset gate region which is formed later by using the porous anodic oxide film 106 as a mask.

Thus, the state shown in FIG. 1B is obtained.

Impurity ions are implanted in this state. Here, P (phosphorus) ions are implanted in order to obtain an N-channel thin film transistor.

When impurity ion implantation is performed in the state shown in FIG. 1B, impurity ions are selectively implanted in the regions 108 and 111. That is, the regions 108 and 111 are high-concentration impurity regions.

The region 109 immediately below the gate electrode 105
, The gate electrode 105 serves as a mask, and impurity ions are not implanted. Then, this region 109 becomes a channel formation region.

Further, since the porous anodic oxide film 105 and the dense anodic oxide film 107 serve as a mask in the region 110, no impurity ions are implanted. The region indicated by 107 is an offset gate region that does not function as a source / drain region or a channel forming region.

The offset gate region functions particularly to reduce the strength of the electric field formed between the channel forming region and the drain region. The presence of the offset gate region can reduce the OFF current value of the thin film transistor and further suppress the deterioration.

Thus, the source region shown by 108,
A channel forming region 109, an offset gate region 110, and a drain region 111 are formed in a self-aligned manner.

After the implantation of the impurity ions is completed, the porous anodic oxide film 106 is selectively removed. Then, an annealing process is performed by irradiation with laser light. At this time, since the laser beam can be applied to the vicinity of the interface between the high concentration impurity region and the offset gate region, the junction portion damaged by the impurity ion implantation can be sufficiently annealed.

When the state shown in FIG. 1B is obtained, a silicon oxide film 112 is formed to a thickness of 2000 Å as a first interlayer insulating film. A silicon nitride film or a laminated film of a silicon oxide film and a silicon nitride film may be used as the first interlayer insulating film.

Next, a contact hole is formed in the first interlayer insulating film 112, and a source electrode 113 that contacts the source region of the thin film transistor is formed. Thus, the state shown in FIG. 1C is obtained.

Next, a second interlayer insulating film 114 is formed using transparent polyimide resin or acrylic resin. The surface of the interlayer insulating film 114 made of this resin material is made flat. Thus, the state shown in FIG. 1D is obtained.

Next, as shown in FIG. 2A, a light-shielding film 115 made of a chromium film which also serves as a light-shielding film of a thin film transistor and a black matrix is formed, and is further patterned to form the light-shielding film 115.

Here, as the resin material forming the second interlayer insulating film 114, one having a relative dielectric constant of 3 or less is selected. Further, the film thickness is increased to several μm. In the case of a resin material, even if the resin material is made thicker, the manufacturing process time does not become longer, so it is useful for such a purpose.

With such a structure, it is possible to suppress the formation of capacitance between the light shielding film 115 made of chromium and the thin film transistor thereunder.

Further, when the second interlayer insulating film 114 is made of a resin material, the surface thereof can be easily flattened, so that the problem of light leakage due to unevenness can be suppressed.

After obtaining the state shown in FIG. 2A, a resin material, or a silicon oxide film or a silicon nitride film is formed as the third interlayer insulating film 116. Here, the third interlayer insulating film 116
A resin material similar to that of the second interlayer insulating film 114 is used as.

The use of a resin material for the third interlayer insulating film can solve the problem that a capacitance is formed between the pixel electrode formed later and the light shielding film 115, and further the pixel electrode is formed. This is useful in the sense that the base can be flattened.

Thus, the state shown in FIG. 2B is obtained. Next, a contact hole is formed, an ITO electrode for forming a pixel electrode is formed by a sputtering method, and further patterning is performed to form a pixel electrode 117.

Thus, the structure shown in FIG. 2C is completed. In the structure shown in FIG. 2C, the relative dielectric constant of the interlayer insulating film provided between the thin film transistor (in particular, the source electrode 113) and the light-shielding film (and / or the black matrix) 115 can be reduced and the thickness thereof can be reduced. Since it is possible to increase the thickness, it is possible to suppress the formation of unnecessary capacitance.

As described above, it is industrially easy to increase the thickness of the resin film, and since the process time does not increase, the above-mentioned structure can be realized.

[Embodiment 2] This embodiment is characterized in that the construction shown in Embodiment 1 is further improved to have a construction having higher reliability.

As described above, a metal material such as chromium is used for the light shielding film and the black matrix. However, considering long-term reliability, there are concerns about the problem of diffusion of impurities from the metal material and the problem of short-circuit with other electrodes or wirings.

In particular, in the state shown in FIG. 2C, when a pinhole exists in the interlayer insulating film 116, the light-shielding film (also serving as a black matrix) 115 and the pixel electrode 117 are short-circuited. Is a problem.

In order to eliminate the influence of pinholes existing in the interlayer insulating film 116, a method of making the interlayer insulating film 116 into a special multilayer film can be considered.

However, such a method is not preferable because it causes an increase in production steps and an increase in production cost.

Therefore, in the structure shown in this embodiment, an anodizable material is used as a light-shielding film for shielding the thin film transistor in the structure shown in the first embodiment, and an anodic oxide film is further formed on the surface thereof.

Aluminum or tantalum can be used as the material that can be anodized. Particularly when aluminum is used, it is suitable as a light-shielding film because the anodized film can be colored black or a dark color close to it by using the anodizing technology used for industrial products such as aluminum sashes. It will be

FIG. 3 shows an outline of the manufacturing process of this embodiment.
First, according to the steps shown in FIGS.
The state shown in (D) is obtained. Next, as shown in FIG. 2A, the light shielding film 115 is formed.

Here, aluminum is used as the light shielding film 115. Then, by performing anodic oxidation in the electrolytic solution, an anodic oxide film 301 is formed on the surface of the light shielding film 115 as shown in FIG.

In the figure, the light shielding film 301 is described as a light shielding film which shields the thin film transistor. However, it usually extends further to form a black matrix.

After obtaining the state shown in FIG.
As shown in (B), the third interlayer insulating film 116 is formed of a silicon oxide film, a silicon nitride film, or a resin material.

Further, as shown in FIG. 3C, the pixel electrode 1
17 is formed with ITO. Here, the interlayer insulating film 11
Even if the pinhole exists in 6, the short circuit between the pixel electrode 117 and the light shielding film 115 due to the existence of the anodic oxide film 301 can be prevented.

Further, since the anodic oxide film 115 is chemically stable, it is possible to prevent impurities from diffusing from the light shielding film 115 to the surroundings in consideration of long-term reliability. .

[Embodiment 3] This embodiment relates to a structure in which the aperture ratio of a pixel is further increased. In general, it is desired that the pixel has a structure in which the aperture ratio is increased as much as possible. In order to increase the aperture ratio of this pixel, it is necessary to arrange the pixel electrode in a large area.

However, if the pixel electrode and the thin film transistor or the wiring overlap with each other, a capacitance is formed between them, so that there is generally a large limitation in this respect.

The present embodiment provides a structure in which the problem that this capacitance is formed is reduced.

FIG. 4 shows a manufacturing process of the structure shown in this embodiment. 4A and 4B are the same as the steps shown in FIGS. 3A and 3B.

First, as shown in FIG. 4A, a light shielding film 115 made of aluminum is formed. Then, an anodic oxide film indicated by 301 is formed on the surface of the light shielding film 115.

Further, as shown in FIG. 4B, a third interlayer insulating film 116 is formed. Here, the interlayer insulating film 116 is formed using a resin material.

Then, as shown in FIG. 4C, a pixel electrode 117 is formed of ITO. Here, the pixel electrode 117
Overlap on the thin film transistor. By doing so, the aperture ratio of the pixel can be maximized.

When the structure shown in FIG. 4C is adopted, the relative dielectric constants of the interlayer insulating films 114 and 116 are low (meaning that it is lower than that of a silicon oxide film or a silicon nitride film).
Since the resin material can be used and the thickness thereof can be increased, the above-mentioned problem of the capacity can be reduced.

The area of the pixel electrode can be increased, and the aperture ratio of the pixel can be increased.

[Embodiment 4] Although the structure of the thin film transistor is a top gate type in the above embodiments, this embodiment shows a manufacturing process of a bottom gate type thin film transistor in which the gate electrode is on the substrate side of the active layer.

FIG. 5 shows the manufacturing process of this embodiment. First, as shown in FIG. 5A, a silicon oxide film 202 is formed as a base film on a glass substrate 201 by a sputtering method. Then 2
A gate electrode indicated by 03 is formed of aluminum.

At this time, scandium was added to aluminum.
Contains 0.18% by weight. In addition, other impurities will be sought to reduce their concentration as much as possible. These measures are for suppressing the formation of protrusions called hillocks or whiskers due to abnormal growth of aluminum in the subsequent process.

Next, a silicon oxide film 204 functioning as a gate insulating film is formed to a thickness of 500Å by plasma CVD.

Further, an amorphous silicon film (not shown) (which later becomes a crystalline silicon film 205), which is a starting film forming an active layer of the thin film transistor, is formed by a plasma CVD method. A low pressure thermal CVD method may be used instead of the plasma CVD method. Next, laser light irradiation is performed to crystallize the amorphous silicon film (not shown). Thus, the crystalline silicon film 205 is obtained. Thus, the state shown in FIG.

After obtaining the state shown in FIG. 5A, the active layer 206 is formed by patterning. Next, a silicon nitride film (not shown) is formed, and exposure is performed from the back surface side of the substrate 201 using the gate electrode 203 to form a mask pattern 207 made of a silicon nitride film. The mask pattern 207 is formed as follows.

First, the pattern of the gate electrode 203 is used to form a resist mask pattern by exposure from the back surface side of the substrate 201. Further, ashing is performed to retreat the resist mask pattern. Then, the silicon nitride film is patterned by using the recessed resist mask pattern (not shown) to obtain a pattern 207. Thus, the state shown in FIG. 5B is obtained.

Next, doping of impurities using the mask pattern 207 is performed. Here, P is used as a dopant.
(Phosphorus) is used, and a plasma doping method is used as a means for doping. In this process, 208 and 2
The region of 09 is doped with P. Further, P is not doped in the region 210.

After the completion of the doping, laser light irradiation is performed from the upper surface to activate the doped region and anneal damage caused by impact of the dopant ions. Thus, the region 208 is formed as the source region as shown in FIG. Also, 209 is formed as a drain region. Also, 210 defines a channel region.

Next, the first interlayer insulating film 2 made of a silicon nitride film is formed.
As a reference numeral 11, a silicon nitride film is formed by plasma CVD
A film is formed to a thickness of 00 °. As the first interlayer insulating film used here, other than the silicon nitride film, a silicon oxide film, a silicon oxynitride film, or a stacked film of a silicon oxide film and a silicon nitride film (the stacking order may be either first). Can be used.

Next, a contact hole for the source region 208 is formed in the first interlayer insulating film 211, and a source electrode 212 that contacts the source region 208 is formed.
Thus, the state shown in FIG. 5C is obtained.

Next, as shown in FIG. 5D, a second interlayer insulating film 213 having a flat surface is formed of transparent polyimide resin or acrylic resin. As a film forming method, for example, a spin coating method may be adopted.

Next, a chrome film is formed on the surface of the second interlayer insulating film 213 and patterned to form a light shielding film 214 which also serves as a light shielding film of a thin film transistor and a black matrix. Then, as the third interlayer insulating film 215, the same resin material film as the second interlayer insulating film 213 is formed.

By etching, contact holes reaching the drain region 209 are formed in the first to third interlayer insulating films 211, 213 and 215. Next, an ITO film is formed on the surface of the third interlayer insulating film 215 and patterned to form a pixel electrode 216 that contacts the drain region 209 of the thin film transistor.

Through the above steps, the thin film transistor shown in FIG. 5D is completed.

[0087]

By utilizing the invention disclosed in this specification, it is possible to effectively arrange the light-shielding film in the structure of the pixel of the active matrix type display device. Then, a structure having a high function as an active matrix display device can be obtained. The invention disclosed in this specification can be applied not only to an active matrix type liquid crystal display device but also to an EL type display device having an active matrix type.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a manufacturing process of a pixel portion of an active matrix circuit.

2A to 2D are diagrams showing a manufacturing process of a pixel portion of an active matrix circuit.

FIG. 3 is a diagram showing a manufacturing process of a pixel portion of an active matrix circuit.

FIG. 4 is a diagram showing a manufacturing process of a pixel portion of an active matrix circuit.

5A to 5C are diagrams showing manufacturing steps of a pixel portion of an active matrix circuit.

[Explanation of symbols]

101 glass substrate (or quartz substrate) 102 base film (silicon oxide film) 103 active layer (crystalline silicon film) 104 gate insulating film (silicon oxide film) 105 gate electrode (aluminum electrode) 106 porous anodic oxide film 107 Dense anodic oxide film 108 Source region (high-concentration impurity region) 109 Channel formation region 110 Offset gate region 111 Drain region (high-concentration impurity region) 112 First interlayer insulating film (silicon oxide film or silicon nitride film) 113 Source electrode 114 second interlayer insulating film (resin material) 115 light shielding film (black matrix) 116 third interlayer insulating film (eg resin material) 117 pixel electrode (ITO electrode)

Claims (9)

[Claims] 1. A thin film transistor whose output is connected to a pixel electrode, an interlayer insulating film made of a resin material, which is arranged above the thin film transistor, and a thin film transistor for shielding the thin film transistor arranged on the interlayer insulating film. A display device comprising: a light-shielding film. 2. An interlayer insulating film made of a resin material is formed on the thin film transistor, and a light shielding film for shielding the thin film transistor is formed on the interlayer insulating film made of the resin material. Display device. 3. A display device according to claim 1, wherein an interlayer insulating film made of a resin material has a flat surface. 4. A display device according to claim 1 or 2, wherein a metal material is used as a material of the light shielding film. 5. A display device according to claim 1, wherein a metal material capable of anodizing is used as a material of the light shielding film, and an anodizing film is formed on the surface thereof. 6. A plurality of pixel electrodes arranged in a matrix, and a black matrix covering at least a part of an edge region of the pixel electrode, wherein the black matrix is on an interlayer insulating film made of a resin material. A display device characterized by being arranged in. 7. A display device according to claim 6, wherein the surface of the interlayer insulating film made of a resin material is flattened. 8. A display device according to claim 6, wherein a metal material is used as a material of the light shielding film. 9. A display device according to claim 6, wherein a metal material capable of anodizing is used as a material of the light shielding film, and an anodizing film is formed on the surface thereof.