JP2001083885A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease pixel defects, to shorten stages and to reduce equipment investment by forming a first substrate higher in mechanical strength than a second substrate and forming the second substrate so as to meet the warpage direction of the first substrate. SOLUTION: This display device consists of a semiconductor substrate 1 as the first substrate having circuit elements 102 for displaying pixels, a transparent counter glass substrate 16 facing the semiconductor substrate 1, a sealing material 104 for forming a cell gap between the semiconductor substrate 1 and the counter glass substrate 16, transparent electrodes 105 and an antireflection coating 106. In such a case, the semiconductor substrate 1 and the counter glass substrate 16 are warped in the same direction so as to avert the generation of mechanical stresses in both of the semiconductor substrate 1 and the counter glass substrate 16. Namely, the device is so constituted that the uniform cell gap is formed without generating the stresses in the semiconductor substrate 1 by warping the semiconductor substrate 1 and the counter glass substrate 16 in the same direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying images, characters, and the like, and more particularly, to a display device using a liquid crystal panel.

[0002]

2. Description of the Related Art A conventional display device using a liquid crystal panel is:
For example, a semiconductor substrate having a semiconductor element and a glass facing the semiconductor substrate (hereinafter referred to as an opposite glass) are attached to each other to obtain a panel having a uniform gap. Techniques for obtaining a panel with this uniform gap include a method of spraying a spacer corresponding to the gap thickness in the display area, increasing the glass facing the semiconductor substrate, and increasing the mechanical strength of the facing glass. And a method of correcting the warpage of the semiconductor substrate in accordance with the facing glass.

[0003]

However, each of these conventional examples has the following problems.

In the method 1), a uniform gap is obtained by spraying a spacer, so that the pixel size becomes smaller as the definition increases, and the aperture ratio decreases due to the presence of the spacer. Otherwise, the image quality is lowered due to factors such as disturbance of liquid crystal alignment. As a result, in an apparatus that performs enlarged projection such as a liquid crystal projection display, the image quality is significantly deteriorated.

2) In the other method, since the semiconductor substrate having the semiconductor element is forcibly flattened by the facing glass having high mechanical strength, a leak current occurs in the semiconductor circuit due to internal stress, and the circuit malfunctions. Or a pixel defect occurs. In addition, since the thickness of the facing glass is increased in order to increase the mechanical strength, there is a problem that the light transmittance is reduced and the brightness of the display itself is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and aims to reduce pixel defects due to stress applied to a semiconductor substrate and eliminate the need to dispose spacers or the like in a display area, thereby reducing the number of processes. It is an object of the present invention to provide a display device capable of achieving a high yield at a low cost by shortening and reducing capital investment.

[0007]

According to a first aspect of the present invention, there is provided a display device, comprising: a first substrate having a circuit element for displaying a pixel; and a first substrate facing the first substrate. A transparent second substrate, wherein the mechanical strength of the first substrate is formed to be higher than that of the second substrate, and the second substrate is bent in a warp direction of the first substrate. It is characterized in that it can be formed according to.

According to a second aspect of the present invention, a material having a small Young's modulus and a small thickness is used for the second substrate.

According to a third aspect of the present invention, the amount of warpage of the second substrate is set to one third or more and three times or less of the amount of warpage of the first substrate.

[Operation] Based on the above configuration, the mechanical strength of the first substrate having the circuit element for displaying pixels is made stronger than that of the second substrate facing the first substrate. By aligning the substrate with the warp direction of the first substrate, both warp directions were aligned to form a uniform gap.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

<First Embodiment> FIG. 1 shows the features of the present invention, and 1 is a circuit element 10 for displaying a pixel.
2, a semiconductor substrate as a first substrate having 2; 16, a transparent counter glass substrate facing the semiconductor substrate 1; 104, a sealing material for forming a cell gap between the semiconductor substrate 1 and the counter glass substrate 16; 105 is a transparent electrode, 106
Is an antireflection coat.

In the present invention, the semiconductor substrate 1 and the opposing glass substrate 16 are warped in the same direction so that no mechanical stress occurs in both the semiconductor substrate 1 and the opposing glass substrate 16.

Hereinafter, the semiconductor substrate 1 and the opposing glass substrate 16
A description will be given of a configuration in which no mechanical stress is generated in both of them.

Originally, the semiconductor substrate 1 and the opposing glass substrate 16
In any case, even if it is a flat surface before processing, a concave or convex warpage is caused by repeated application of some thermal stress or film formation during processing. When stress generated when correcting the warpage is applied to the semiconductor substrate 1 in particular, a defect occurs in the circuit element 102,
This causes an increase in leakage current between the junctions and causes pixel defects.

According to the present invention, the semiconductor substrate 1 and the opposing glass substrate 16 are warped in the same direction so that a stress is not generated in the semiconductor substrate 1 and a uniform cell gap is formed.

FIG. 2 is a detailed sectional view of a liquid crystal panel portion on which a semiconductor element is mounted.

In FIG. 1, reference numeral 1 denotes a semiconductor substrate;
Are P-type and N-type well regions, 3, 3 'are transistor source regions, 4 is a gate region, 5, 5' are drain regions, 6 is a field oxide film, 8, 8 'and 18 are B
An insulating layer such as PSG (Boron-Phosphorous-Doped-Silica-Glass);
Is a pixel electrode, 7 is a light-shielding layer covering a display region and a peripheral region formed of Ti, Tin, or the like. 9 is provided between the pixel electrode 12 and the light-shielding layer 7 for each pixel and between each pixel electrode 12. The insulating layer 9 serves as a charge storage capacitor of the pixel electrode 12. Further, 14 is a liquid crystal material, 15 is a common transparent electrode facing the pixel electrode 12, 16 is a transparent counter glass substrate, 19 is a display area, 20 is an antireflection film, 1
Reference numerals 7 and 17 'denote high-concentration impurity regions. In addition, 22 is a seal, 23 is a through-hole portion, and 24 is a semiconductor device portion.

Among these, the main causes of warpage of the semiconductor substrate 1 are the field oxide film 6, the film between the insulating layers 8, 8 'and 18, and the pixel electrode 12
It is. Due to the interaction between these films, in the configuration of FIG. When this element is diced into, for example, a 1.5-inch rectangle, it warps to a concave shape of about 1.0 μm. In order to reduce the warpage, there are techniques such as increasing the thickness of the opposing glass substrate 16 and changing the film configuration of the field oxide film 6 and the like. The mainstream is 7 mm, and the Si substrate is 0.625 mm.
Alternatively, a great deal of cost is required, such as remodeling of the process equipment, which is not practical.

When the semiconductor substrate 1 having the semiconductor element (circuit element) 102 is bonded to the opposite glass substrate 16 having high mechanical strength and the semiconductor substrate 1 is forcibly flattened, the drain region 5 Field oxide film 6 between 5 ′ and well regions 2 and 2 ′ (between PN junctions)
In the bird's peak portion (between the PN junction under the oxide film), a leak current due to stress occurs. This causes a problem that a circuit malfunction or a pixel defect occurs.

There is also a method of reducing the amount of warpage by changing the film configuration, but this deprives the semiconductor process design freedom and causes a reduction in yield. Therefore, it is extremely difficult to form the semiconductor substrate 1 without any warpage.

On the other hand, the shape of the warpage of the opposing glass substrate 16 can be arbitrarily changed. As shown in FIG. 1, the antireflection film 106 for improving the transmittance of light incident on the light valve and reducing the reflectance is made of, for example, Al ₂ O ₃ or Mg.
When formed in a three-layer structure of F ₂ and ZrO ₃ , it can be formed in a concave shape as in FIG.

A uniform gap can be formed by bonding the concave portions formed in this manner. The warpage amount is, for example, 1.0 μm for the semiconductor substrate 1.
m, the opposite glass substrate 16 is 0.3 to 3 μm.
It may be warped in an m-concave shape, and preferably 0.6 to 1.
The concave warpage of 5 μm, more preferably 0.8 to 1.2 μm is good. In order to control the amount of warpage, the thickness of the opposing glass substrate 16 may be changed. Generally, when the same film is formed on glass, the thickness of the glass is reduced by 2 mm.
The amount of warpage changes in inverse proportion to the power. For example, the aforementioned Al ₂
In the case of the antireflection film 106 formed of a three-layer structure of O ₃ , MgF ₂ , and ZrO ₃ , a concave warp of 1.0 μm can be obtained by using a glass having a thickness of 1.1 mm.

Also, if the glass thickness is the same, the warpage can be reduced by using a material having a large Young's modulus, and conversely, the warpage can be increased by using a material having a small Young's modulus. In order to change the thickness of the glass, for example, the surface of the glass may be polished.

The semiconductor substrate 1 and the opposing glass substrate 16
In order to form a uniform gap, it is important that both have exactly the same shape or that the semiconductor substrate 1 side is not substantially deformed, and that the mechanical strength of the semiconductor substrate 1 side is lower. It is important to be strong. For that purpose, it is required that a material having a small Young's modulus be used for the counter glass substrate 16 side and that the plate thickness be as small as possible.
For example, comparing Si and NA35 glass,
625mm, Young's modulus is 1657kg / m
m ² , NA35 glass is 7000 kg / mm ² .
The range in which the opposing glass substrate 16 can form a uniform gap similar to Si when using NA35 glass having a plate thickness of 1.1 mm or less will be described below. That is, the required gap variation varies depending on the liquid crystal used, the application, and the like. However, in order to suppress the gap variation to within 0.6 μm, the facing glass has to be warped up to 1/3 to 3 times the Si semiconductor substrate 1. It is sufficient if the warpage of the substrate 16 can be controlled, and if it is controlled to have a gap variation of 0.3 μm or less, it can be up to 2/3 to 1.5 times, more preferably 0.8 to 1.2 times of the counter glass substrate 16. What is necessary is to use the thing of the amount of warpage within.

In this embodiment, the present invention has been described by taking a reflection type light valve as an example. However, a transmission type light valve can be handled similarly.

<Second Embodiment> FIG. 3 shows a second embodiment of the present invention.
And the basic configuration is the same as that of FIG. The difference is that the warp direction of the semiconductor substrate 1a is convex. In FIG. 2, such a shape may occur when a semiconductor substrate having a strong Tensile stress such as Ti is used for the semiconductor substrate. In such a case, for example, a T
The direction of the warpage can be controlled by forming an enile film of about 20 to 100 μm and forming an IT0 film thereon. With respect to this amount of warpage, it is possible to form an amount of warpage having the same shape as that of the semiconductor substrate 1a by using materials having different thicknesses and Young's moduli of glass.

<Third Embodiment> FIG. 4 shows a third embodiment of the present invention.
1 shows an embodiment of the present invention. The opposing glass substrate 16b of the present embodiment is obtained by previously polishing glass to the same shape with respect to the semiconductor substrate 1b.

The polishing of the opposing glass substrate 16b may be performed on both surfaces, or may be performed only on the surface opposing the semiconductor substrate 1b. When it is necessary to form an anti-reflection film on the polished glass, these may be used in combination to adjust the amount of warpage.

[0030]

As described above, according to the present invention,
The first substrate having a circuit element for displaying pixels has a higher mechanical strength than a second substrate facing the first substrate, and the second substrate is aligned with a warp direction of the first substrate. As a result, a uniform gap can be formed by aligning both warping directions, thereby reducing defects of circuit elements due to stress applied to the first substrate having a circuit for displaying pixels, Pixel defects can be reduced.

In addition, the above configuration eliminates the need to dispose a spacer or the like in the display area.
It is possible to provide a display device with low cost and high yield by shortening the process and reducing capital investment.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a detailed sectional view of a liquid crystal panel section on which a semiconductor element according to the present invention is mounted.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 first substrate (semiconductor substrate) 16 second substrate (opposing glass substrate) 102 circuit element

Continued on the front page F term (reference) 2H089 LA11 NA24 NA60 PA19 QA04 QA11 QA12 QA14 QA16 SA01 TA01 TA09 2H090 JA03 JA08 JA16 JB04 JC04 JC06 JC14 JC17 JD13 JD18 2H092 GA59 JA23 JB13 KA03 KA07 NA07 NA17 NA25 NA25 NA25 BB12 EE33 EE35 FF00 HH03

Claims (3)

[Claims] 1. A display device comprising: a first substrate having a circuit element for displaying a pixel; and a transparent second substrate facing the first substrate, wherein the first substrate is formed from the second substrate. A display device, wherein the mechanical strength of the substrate is increased, and the second substrate can be formed in accordance with the warping direction of the first substrate. 2. The display device according to claim 1, wherein a material having a small Young's modulus and a small plate thickness is used for the second substrate. 3. The display according to claim 1, wherein the amount of warpage of the second substrate is not less than one third and not more than three times the amount of warpage of the first substrate. apparatus.