CN1651966A - Optical interferometric display unit - Google Patents

Abstract

An optical interference display unit at least comprises a light incident electrode and a light reflecting electrode on a transparent substrate. The light incident electrode at least comprises a transparent conductive layer and a dielectric layer, and the light reflecting electrode at least comprises a light absorption layer and a light reflecting layer.

Description

Optical interferometric display unit

technical field

The present invention relates to an optical interference display panel, and in particular to a color-variable pixel unit of the optical interference display panel.

Background technique

Due to the characteristics of small size and light weight, the flat panel display has great advantages in the portable display device and the display market for small space applications. In addition to liquid crystal display (Liquid Crystal Display, LCD), organic electro-luminescent display (Organic Electro-Luminescent Display, OLED) and plasma display (Plasma Display Panel, PDP), etc., today's flat-panel display is a flat-panel display that uses light interference. Display mode has been raised.

Please refer to U.S. Patent No. 5,835,255, which discloses an array of visible light interference display units (Array of Modulation), which can be used as a flat-panel display. Please refer to FIG. 1 . FIG. 1 is a schematic cross-sectional view of a conventional optical interference display unit. Each light interference display unit 100 includes a light incident electrode 102 and a light reflective electrode 104 formed on a transparent substrate 105, and a cavity (Cavity) is formed between the light incident electrode 102 and the light reflective electrode 104 supported by a support 106. )108. The distance between the light incident electrode 102 and the light reflective electrode 104 , that is, the length of the cavity 108 is D. The light incident electrode 102 is a partially penetrating reflective layer with a light absorption rate that can absorb part of visible light, and the light reflective electrode 104 is a reflective layer that can be deformed by voltage driving, wherein the light incident electrode 102 includes transparent conductive layer 1021 , absorber layer 1022 and dielectric layer 1023 . When the incident light passes through the light incident electrode 102 and enters the chamber 108, among all the wavelengths (Wave Length, represented by λ) of the visible light spectrum of the incident light, only the wavelength (λ1) that meets the formula 1.1 can produce constructive interference And the output. where N is a natural number. in other words,

2D=Nλ (1.1)

When the length D of the chamber 108 satisfies an integral multiple of half the wavelength of the incident light, constructive interference can be generated to output a steep light wave. At this time, the observer's eyes observe along the direction of the incident light, and can see the reflected light with the wavelength λ1. Therefore, the light interference display unit 100 is in an "on" state.

FIG. 2 is a schematic cross-sectional view of a conventional optical interference display unit after voltage is applied. Referring to FIG. 2 , driven by the voltage, the light reflective electrode 104 deforms due to electrostatic attraction, and collapses toward the light incident electrode 102 . At this time, the distance between the light incident electrode 102 and the light reflective electrode 104 , that is, the length of the cavity 108 is not zero, but d, and d can be equal to zero. At this time, D in Formula 1.1 will be replaced by d, and among all the wavelengths λ of the visible light spectrum of the incident light, only the visible light wavelength (λ2) conforming to Formula 1.1 can produce constructive interference, and pass through through the reflection of the light reflective electrode 104 The light enters the electrode 102 and is output. The light incident electrode 102 has a higher light absorption to the light of wavelength λ2, at this moment, all visible light spectrums of the incident light are all filtered out, and for observers observing along the direction of the incident light incident electrode 102, there will be no Any reflected light in the visible light spectrum will be seen, therefore, for the optical interferometric display unit 100 to be in an "off" state.

The light incident electrode 102 is a partially penetrating and partially reflective electrode. When the incident light passes through the light incident electrode 102 , part of the intensity of the incident light is absorbed by the absorbing layer 1022 . Wherein, the material forming the transparent conductive layer 1021 can be a transparent conductive material, such as indium tin oxide glass (ITO) or indium zinc oxide glass (IZO), and the material forming the absorbing layer 1022 can be metal, such as aluminum, chromium, silver, etc. wait. The material for forming the dielectric layer 1023 can be silicon oxide, silicon nitride or metal oxide. Parts of metal oxides can be obtained by direct oxidation of part of the absorber layer. The light reflective electrode 104 is a deformable reflective electrode, which can deform and move up and down under the control of voltage. The light reflective electrode 104 is formed by a reflective layer and a mechanical stress adjustment layer, and the material forming the reflective layer can be metal material/transparent conductive material. Generally speaking, metal materials suitable for forming the reflective layer, such as silver, have low stress, while metals with high stress, such as chromium, have poor reflectivity, so a metal with good reflectivity is needed to form the reflective layer and a metal with high stress The metal forms the mechanical stress adjustment layer to make the light reflective electrode 104 a movable and reflective electrode.

The characteristics of the display formed by this visible light interference type display unit array are essentially low power consumption, fast response (Response Time) and bi-stable (Bi-Stable) characteristics, which will be applied to the panel of the display. Especially in portable (Portable) products, such as mobile phone (Mobile Phone), personal digital assistant (PDA), portable computer (Portable Computer) and so on.

In the manufacture of an existing optical interference display unit, an indium tin oxide glass layer is first formed on a transparent substrate, a metal absorption layer is formed on the indium tin oxide glass layer, and then a dielectric layer is formed on the metal absorption layer. There will be a lot of hetero-atoms (hetero-atoms) such as oxygen and nitrogen in the process of the indium tin oxide layer and the dielectric layer, so the manufacturing process of the metal absorption layer needs to be carried out in another reaction chamber to avoid the hetero-atoms pollution, and at the same time, this also increases the complexity of the production process.

Contents of the invention

Existing production process Production process Production process

According to the above, the object of the present invention is to provide a light interference display unit, in which the light absorbing layer on the light incident electrode is removed, so that the light incident electrode can be fabricated in the same deposition process reaction chamber.

Another object of the present invention is to provide an optical interference display unit, in which a light absorbing layer is disposed on the reflective electrode, which can avoid contamination by heteroatoms, and thus has stable quality and high yield in the manufacturing process.

Another object of the present invention is to provide a light interference display unit, which is a reflective electrode composed of a light absorbing layer and a light reflecting layer, without an additional mechanical stress adjustment layer, so that the manufacturing process can be simplified, the cost can be reduced, and the manufacturing process can be improved. Rate.

According to the above-mentioned purpose of the present invention, on the one hand the present invention proposes a kind of manufacturing method of light interference type display unit, on a transparent base, earlier form transparent conductive layer and an optical thin film layer sequentially to form light reflective electrode, wherein optical thin film The layer may be a dielectric layer. A sacrificial layer is formed on the optical thin film layer, and openings are formed in the light reflective electrode and the sacrificial layer to be suitable for forming a support therein. Next, a first photoresist layer is spin-coated on the sacrificial layer to fill the opening. The support is formed by patterning the photoresist layer through a photolithography process. The sacrificial layer can be made of opaque material such as metal, or a common dielectric material.

A light absorption layer and a light reflection layer are sequentially formed on the sacrificial layer and the support to form a light reflection electrode. Finally, a structure release etching process is used to remove the sacrificial layer to form a light interference display unit.

According to the light interference display unit formed in the aforementioned manufacturing process, the light interference display unit can be formed on a transparent substrate, at least including a light incident electrode and a light reflection electrode, the light incident electrode and the light reflection electrode are supported by supported by objects forming a cavity therebetween. The light incident electrode is composed of a transparent conductive layer and an optical film layer, and the light reflection electrode is formed of a light absorption layer and a light reflection layer.

When the light is incident from the light incident electrode, it passes through the transparent substrate, the transparent conductive layer and the optical film layer and directly reaches the light absorbing layer, and the light absorbing layer absorbs part of the incident light, reducing the intensity of the incident light by at least about 30%. . Then, the incident light is reflected by the reflective layer of the reflective electrode. When the length of the chamber is fixed, only the wavelengths that meet the formula 1.1 can pass through the incident electrode and pass through the light interference display unit to be seen by the observer. arrive.

According to the light interference type display unit disclosed by the present invention, the existing light absorbing layer must be placed on the arrangement of the incident electrodes, and the light absorbing layer is placed on the light reflective electrodes. Secondly, the structure of the transparent conductive layer, the light absorbing layer and the light film layer of the existing light incident electrode is very thin (less than 100 Angstroms) due to the metal material forming the light absorbing layer. Slight pollution, such as heteroatoms in the formation of transparent conductive layers and optical thin film layers, will have a great impact on the uniform thickness and stable properties of the light-absorbing layer. Therefore, the production process needs to be divided into two production processes. chamber, and three film layers are formed alternately in the two reaction chambers. Even so, the ultra-thin metal absorbing layer is still unavoidably affected by the two manufacturing processes, which slightly affects its quality. However, according to the optical interference display unit proposed by the present invention, the transparent conductive layer and the optical film layer are first manufactured in sequence, and then a sacrificial layer of several microns to tens of microns is formed. Generally speaking, the sacrificial layer can be made of metal or silicon. . After the support is formed, the light absorbing layer is formed on the sacrificial layer and the support, and finally the light reflection layer is formed. Since the sacrificial layer is thick enough to avoid contamination of the light-absorbing layer by residual heteroatoms during the formation of the transparent conductive layer and the optical thin film layer, the light-absorbing layer with a thickness of only tens to hundreds of Angstroms (Angstroms) can have quite good quality and uniformity, and the sacrificial layer will be removed at the end, so it will not affect the light absorbing layer and the light reflecting layer at all.

In addition, the mechanical stress of the light-absorbing layer can be increased by adjusting the production process parameters for forming the light-absorbing layer, such as reducing the power used when depositing metal materials or reducing the film-forming speed. Therefore, the light absorbing layer can also have the function of the existing mechanical stress adjustment layer, and the existing mechanical stress adjustment layer is not necessary in the present invention. The manufacturing process parameters for forming the light absorbing layer will depend on the material and thickness of the light reflecting layer and the material and thickness of the light absorbing layer.

The optical interference type display unit manufactured according to the manufacturing method provided by the present invention has the following advantages. First, the steps of the manufacturing process are simplified and possible pollution in the manufacturing process can be avoided, thereby improving the manufacturability of the optical interference type display unit and the resulting The characteristics of the produced panel are relatively stable and the quality is better; secondly, because the light absorbing layer in the light reflective electrode can be used as a mechanical stress adjustment layer, the existing mechanical stress adjustment layer is not necessary in the present invention.

In order to further illustrate the above-mentioned purpose, structural features and effects of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a schematic cross-sectional view illustrating an existing optical interference display unit;

FIG. 2 is a schematic cross-sectional view showing a voltage applied to an existing optical interference display unit; and

3A to 3C are diagrams illustrating a manufacturing method of an optical interference display unit according to a preferred embodiment of the present invention.

Detailed ways

In order to make the light interference display unit provided by the present invention more clear, the manufacturing method and structure of the light interference display unit disclosed in the present invention are described in detail in the preferred embodiment.

Please refer to FIG. 3A to FIG. 3C . FIG. 3A to FIG. 3C illustrate a manufacturing method of an optical interference display unit according to a preferred embodiment of the present invention. Please refer to FIG. 3A, a transparent conductive layer 302 is first formed on a transparent substrate 300, and the material for forming the transparent conductive layer 302 can be, for example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZO) , indium oxide (IO), or more than one of the aforementioned materials can be used in combination. The thickness of the transparent conductive layer 302 depends on requirements, generally ranging from tens of angstroms to thousands of angstroms.

After forming the transparent conductive layer 302 , at least one optical film layer 304 is formed on the transparent conductive layer 302 . The material forming the optical film layer 304 is a dielectric material, such as silicon oxide, silicon nitride, or metal oxide. The transparent conductive layer 302 and the optical film layer 304 constitute a light incident electrode 306 . Next, a sacrificial layer 308 is formed on the optical thin film layer 304. The material for forming the sacrificial layer 308 can be metal or silicon, such as molybdenum metal, magnesium metal, molybdenum alloy, magnesium alloy, single crystal silicon, polycrystalline silicon and amorphous Silicon, etc., the thickness of the sacrificial layer 308 is from several micrometers to tens of micrometers, depending on the wavelength of the reflected light of the optical interference display unit.

The opening 310 is formed in the light incident electrode 306 and the sacrificial layer 308 by a photolithographic etching process, and the opening 310 is suitable for forming a support therein.

Next, a material layer 312 is formed on the sacrificial layer 308 and fills up the opening 310 . The material layer 312 is suitable for forming a support. Generally, photosensitive materials, such as photoresist, or non-photosensitive polymer materials, such as polyester or polyamide, can be used. If a non-photosensitive material is used to form the material layer, a photolithography and etching process is required to form a support on the material layer 312 . In this embodiment, the photosensitive material is used to form the material layer 312 . Referring to FIG. 3B , only one photolithography process is required to pattern the material layer 312 . The support 314 is formed by patterning the material layer 312 shown in FIG. 3A through a photolithography process.

Next, a metal layer 316 is first formed on the sacrificial layer 308 and the support 314 as a light absorbing layer. The metal suitable for forming the metal layer 316 can be chromium, molybdenum, chromium-molybdenum alloy, chromium alloy, and molybdenum alloy. The thickness of the metal layer 316 is about tens of angstroms to 200 angstroms. Next, the light reflective layer 318 is formed on the metal layer 316 . Generally speaking, the material for forming the light reflective layer 318 is a metal material, such as silver, aluminum, silver alloy or aluminum alloy. The metal layer 316 and the light reflection layer 318 constitute a light reflection electrode 320 .

Referring to FIG. 3C, the sacrificial layer 308 shown in FIG. 3B is removed by structure release etching (Release Etch Process) to form a cavity 322 (the location of the sacrificial layer 308). As the light interference display unit 324 formed in the above-mentioned manufacturing process, the light interference display unit 324 is located on a transparent substrate 300, and at least includes a light incident electrode 306 and a light reflection electrode 320, the light incident electrode 306 and the light reflection electrode 320. The electrodes 320 are supported by the supports 314 to form a cavity 322 therebetween. The light incident electrode 306 is formed by the transparent conductive layer 302 and the optical film layer 304 , and the light reflective electrode 320 is formed by a metal (light absorbing) layer 316 and a light reflective layer 318 .

In addition, if the stress structure of the light reflective electrode 320 needs to be enhanced, a mechanical stress adjustment layer (not shown in the figure) can be formed on the light reflective layer 318 to adjust the stress of the light reflective electrode 320 .

The present invention removes the light absorbing layer originally located on the light incident electrode and arranges it on the light reflective electrode. Such a structural design can simplify the steps of the manufacturing process and avoid possible contamination of the light-absorbing layer during the manufacturing process and affect the quality of the light-absorbing layer, thereby improving the manufacturability of the light-interference display unit and the produced The characteristics of the panel are more stable and the quality is better. Secondly, since the light-absorbing layer in the light-reflecting electrode can be used as a mechanical stress adjustment layer, the mechanical stress adjustment layer may not be used, and one manufacturing process is omitted, which can increase productivity and reduce manufacturing costs.

Although the present invention has been described with reference to the current specific embodiments, those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention, and other modifications can be made without departing from the spirit of the present invention. Various equivalent changes and modifications, therefore, as long as any changes and modifications within the scope of the true spirit of the present invention will fall within the scope of the claims of the present invention.

Claims (10)

1. light interference type display unit comprises at least:

One incident electrode, this incident electrode comprises:

One transparency conducting layer; And

One is positioned at the optical thin film layer on this transparency conducting layer;

One reflecting electrode, this reflecting electrode comprises:

One light absorbing zone; And

One is positioned at the reflection layer on this light absorbing zone; And

At least two stilts to be supporting this light incident electrode and this light reflecting electrode, and form a chamber between this light incident electrode and this light reflecting electrode.

2. light interference type display unit as claimed in claim 1 is characterized in that this light interference type display unit system is positioned on the transparent substrates.

3. light interference type display unit as claimed in claim 1, the material that it is characterized in that forming this transparency conducting layer is to be selected from one of tin indium oxide, indium zinc oxide, zinc paste, indium oxide and combination in any thereof.

4. light interference type display unit as claimed in claim 1, it is characterized in that forming this optical thin film layer is a dielectric layer.

5. light interference type display unit as claimed in claim 4 is characterized in that this dielectric layer is monox, silicon nitride or metal oxide.

6. light interference type display unit as claimed in claim 1, the material that it is characterized in that this light absorbing zone is a metal.

7. light interference type display unit as claimed in claim 6 is characterized in that this metal is to be chromium, molybdenum, chrome molybdenum, evanohm or molybdenum alloy.

8. light interference type display unit as claimed in claim 1, the material that it is characterized in that this reflection layer is a metal.

9. light interference type display unit as claimed in claim 8 is characterized in that this metal is to be silver, aluminium, silver alloy or aluminium alloy.

10. light interference type display unit as claimed in claim 1 is characterized in that this light reflecting electrode comprises that also one is positioned at the mechanical stress adjustment layer on this reflection layer.

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