CN100346223C - Reflection type interference regulating display element and method for manufacturing same - Google Patents

Abstract

The invention provides a reflective interference adjustment display element and a manufacturing method thereof. A layer of protective layer is covered on the surface of the lower electrode of the reflective interference adjustment display element facing the cavity. Therefore, when etching the sacrificial layer between the upper and lower electrodes, the protective layer can protect the surface of the lower electrode from being damaged by the etchant, so that the distance between the upper and lower electrodes will not change and affect the reflection of the element. output light wavelength.

Description

Reflective interference adjustment display element and manufacturing method thereof

technical field

The invention relates to a plane display element and a manufacturing method thereof, in particular to a reflective interference adjustment display element and a manufacturing method thereof.

Background technique

Due to the characteristics of small size and light weight, the flat panel display has great advantages in the market of portable display devices and displays for small space applications. In addition to liquid crystal displays (LiquidCrystal Display; LCD), organic electroluminescent displays (Organic Electro-Luminescent Display; OLED) and plasma flat panel displays (Plasma Display Panel; PDP), etc., today's flat-panel displays use light reflection Interferometric modulation of planar display modes has been proposed.

The characteristics of the display formed by the variable color pixel unit array adjusted by light reflection interference interference are essentially low power consumption, fast response (Response Time) and bi-stable (Bi-Stable) characteristics, and will be applicable to The panel of the display, especially in the application of portable (Portable) products, such as mobile phone (Mobile Phone), personal digital assistant (PDA), portable computer (Portable Computer) and so on.

US Patent No. 5,835,255 discloses a visible light adjustment element group (Visible Spectrum Modulation Arrays), the constituent unit of which is a variable color pixel unit, which can be used as a flat panel display. Please refer to FIG. 1A , which is a schematic cross-sectional structure diagram of a color-changing pixel unit in the prior art. Each color-variable pixel unit 100 on the transparent substrate 110 includes a lower electrode 102 and an upper electrode 104 , and a cavity (Cavity) 108 is formed between the lower electrode 102 and the upper electrode 104 supported by a support 106 . The distance between the lower electrode 102 and the upper electrode 104 , that is, the length of the cavity 108 is D, and the length D of the cavity 108 is generally less than 1 μm. The lower electrode 102 is a light incident electrode, which has light absorption rate and can absorb part of visible light. The upper electrode 104 is a light reflective electrode, which can be deformed by voltage driving.

Generally, white light is used as the incident light source of the color-changing pixel unit 100 , and the white light is composed of light rays of different wavelengths (Wave Length, represented by λ) in the visible light spectrum range. When the incident light enters the chamber 108 through the lower electrode 102, only the incident light conforming to the wavelength limit in formula 1.1 will generate constructive interference in the chamber 108 and be reflected and output, where N is a natural number. in other words,

2D=Nλ ₁ (1.1)

When the double length 2D of the chamber 108 satisfies an integer multiple of the incident light wavelength _λ1 , the incident light wavelength _λ1 can be made to produce constructive interference in the chamber 108, and the reflected light of the wavelength _λ1 is output. At this time, the observer's eyes observe along the direction of the incident light incident on the lower electrode 102, and can see the reflected light with a wavelength of _λ1 . Therefore, the variable color pixel unit 100 is in an "on" state, that is, A bright state.

FIG. 1B is a schematic cross-sectional view of the color-changing pixel unit 100 in FIG. 1A after voltage is applied. Referring to FIG. 1B , under the driving of the voltage, the upper electrode 104 will deform due to electrostatic attraction, and collapse in the direction of the lower electrode 102 .

At this time, the distance between the lower electrode 102 and the upper electrode 104 , that is, the length of the cavity 108 is d, and this d may be equal to zero. That is to say, D in formula 1.1 will be replaced by d, and among all the wavelengths of light in the incident light, only the wavelength (λ ₂ ) conforming to formula 1.1 can produce constructive interference in the chamber 108, via the upper electrode 104 The reflection passes through the lower electrode 102 to be output. In this variable color pixel unit 100, the lower electrode 102 is designed to have a higher light absorptivity for light with a wavelength of _λ2 , so all light rays in the incident light are filtered out, and the lower electrode 102 is designed to pass along the incident light to the lower electrode. An observer looking in the direction of 102 will not see any light being reflected. Therefore, at this time, the color-changing pixel unit 100 is in an “off” state, that is, a dark state.

As mentioned above, under the driving of voltage, the upper electrode 104 will deform due to the electrostatic attraction, and collapse in the direction of the lower electrode 102, so that the color-changing pixel unit 100 is switched from the "on" state to the "off" state. state. When the color-changing pixel unit 100 is to be switched from the “off” state to the “on” state, the voltage used to drive the upper electrode 104 to deform must be removed first. Then, relying on its own deformation recovery force, the upper electrode 104 that has lost the electrostatic attraction will return to the original state as shown in FIG. 1A , so that the color-changing pixel unit 100 presents an "on" state.

It can be seen from the above that the color-variable pixel unit 100 is formed by combining the principle of optical thin film interference, reflective plate manufacturing process and MEMS architecture manufacturing process. The uppermost optical thin film of the lower electrode 102 is generally made of insulating materials commonly used in semiconductor manufacturing processes, such as silicon oxide or silicon nitride. In MEMS architecture, the cavity 108 is formed by etching the sacrificial layer between the upper electrode 104 and the lower electrode 102 . The material of the sacrificial layer is mostly metal, polysilicon or amorphous silicon, especially the material containing silicon is paid more attention in process development because of its low cost. However, if the etchant used when etching the sacrificial layer has poor etching selectivity for the sacrificial layer and the optical film, the surface of the lower electrode 102 is often damaged during the etching of the sacrificial layer, causing the cavity The change of the width D of 108 and the damage of the optical film properties of the lower electrode, that is, the change of the input light wavelength _λ1 of the color-changing pixel unit 100, thus affecting the color uniformity of the display.

Contents of the invention

The object of the present invention is to provide a reflective interference adjustment display element and its manufacturing method. A protective layer is formed on the optical film of the lower electrode of the reflective interference adjustment display element to protect the lower electrode of the reflective interference adjustment display element. Optical film.

Another object of the present invention is to provide a reflective interference adjustment display element and its manufacturing method. A protective layer is formed on the optical film of the lower electrode of the reflective interference adjustment display element to make the lower electrode of the reflective interference adjustment display element The optical film quality of the electrode is stable.

Another object of the present invention is to provide a reflective interference modulation display element and its manufacturing method, which are used to improve the display quality and reliability of the reflection interference modulation display panel.

In order to achieve the above object of the present invention, the present invention proposes a method for manufacturing a reflective interference adjustment display element, which at least includes the following steps: sequentially forming a first transparent conductive layer, a light absorbing layer, and an insulating layer on a transparent substrate , protective layer and sacrificial layer. Then at least two straight strip-shaped first openings are formed among the sacrificial layer, the protective layer, the insulating layer, the light absorbing layer and the first transparent conductive layer to define the lower electrode, wherein the lower electrode is composed of the first transparent conductive layer, The light absorbing layer, insulating layer and protective layer are stacked. Next, a layer of photosensitive material is coated on the transparent substrate to fill the first opening and cover the sacrificial layer, and then the photosensitive material is patterned to form a support in the first opening. Then, a second conductive layer is formed on the sacrificial layer and the support, and at least two second openings are formed therein to define at least one upper electrode, wherein the upper electrode is formed by the defined second conductive layer. composition, and the extending direction of the above-mentioned second opening is perpendicular to the extending direction of the above-mentioned first opening. Next, the above-mentioned sacrificial layer is removed, wherein the above-mentioned protective layer protects the insulating layer from being damaged during removal.

In order to achieve the above object of the present invention, a reflective interference adjustment display element is proposed, the display element at least includes a lower electrode, an upper electrode, a support and a protective layer. The upper electrode and the lower electrode are arranged in parallel, the support is located between the lower electrode and the upper electrode to form a chamber for interference of incident light, and the protective layer is covered on the surface of the lower electrode facing the chamber. When etching the sacrificial layer between the lower electrode and the upper electrode, the protective layer is used to protect the surface of the lower electrode from being damaged by the etchant used for etching the sacrificial layer.

According to a preferred embodiment of the present invention, the above-mentioned protection layer is preferably made of silicon-free material, such as metal oxide. Usable metal oxides are, for example, aluminum oxide, titanium oxide or tantalum oxide.

In the present invention, a protective layer is covered on the surface of the lower electrode, so that the lower electrode will not be corroded by the used etchant when the sacrificial layer is removed. Therefore, the structure of the optical thin film of the bottom electrode can be kept intact, and its property can be stabilized to provide high-quality image display.

Description of drawings

The technical solutions and other beneficial effects of the present invention will be apparent through the detailed description of specific embodiments of the present invention below in conjunction with the accompanying drawings.

In the attached picture,

FIG. 1A is a schematic cross-sectional structure diagram of a color-changing pixel unit in the prior art.

FIG. 1B is a schematic cross-sectional view of the color-changing pixel unit 100 in FIG. 1A after voltage is applied.

2A-2D are cross-sectional diagrams showing the manufacturing process of a reflective interference modulation display element according to a preferred embodiment of the present invention.

Detailed ways

In the manufacturing process of the reflective interference adjustment display element, in order to solve the problem that the optical film of the lower electrode is also damaged when the sacrificial layer is removed in the prior art, the present invention provides a reflective interference adjustment display element and its manufacture method. In a preferred embodiment of the present invention, a protective layer is covered on the surface of the lower electrode, so that the lower electrode will not be corroded by the etchant used when removing the sacrificial layer. Therefore, the structure of the optical thin film of the bottom electrode can be kept intact, and its property can be stabilized to provide high-quality image display.

Please refer to FIGS. 2A-2D , which are cross-sectional views of the manufacturing process of a reflective interference-adjusting display element according to a preferred embodiment of the present invention. In FIG. 2A , a first transparent conductive layer 205 , a light absorbing layer 210 , an insulating layer 215 , a protective layer 220 and a sacrificial layer 225 are sequentially formed on a transparent substrate 200 .

The material of the above-mentioned first transparent conductive layer 205 can be, for example, indium tin oxide (Indium Tin Oxide; ITO), indium zinc oxide (Indium Zinc Oxide; IZO), zinc oxide or indium oxide, and the material of the light absorbing layer 210 can be, for example, Metals such as aluminum, silver or chrome, etc. The material of the insulating layer 215 can be silicon oxide or silicon nitride, for example, the material of the sacrificial layer 225 can be amorphous silicon or polysilicon, and the material of the protection layer 220 is preferably a silicon-free material, such as metal oxide. Usable metal oxides include dielectric materials such as aluminum oxide, titanium oxide, or tantalum oxide.

In FIG. 2B, at least two straight first openings 230 are formed in the sacrificial layer 225, the protective layer 220, the insulating layer 215, the light absorbing layer 210 and the first transparent conductive layer 205, defining the position of the lower electrode. That is, between the two first openings 230 . Next, a layer of photosensitive material 235 is coated on the sacrificial layer 225 and in the first opening 230 . The direction of the above-mentioned first opening 230 is vertical to the paper surface, and its forming method can be, for example, a lithography etching method. The bottom electrode is formed by stacking the defined first transparent conductive layer 205 , the light absorbing layer 210 , the insulating layer 215 and the protective layer 220 . The photosensitive material 235 mentioned above can be, for example, positive photoresist, negative photoresist or various photosensitive polymers, such as polyimide, acrylic resin or epoxy resin.

In FIG. 2C , the photosensitive material 235 in the first opening 230 undergoes a chemical reaction to form the support 240 in the first opening 230 by using the exposure and development method. Then a second conductive layer 250 is formed on the sacrificial layer 225 and the support 240, and then at least two straight second openings (not shown) are formed in the second conductive layer 250 to define at least one upper electrode, namely Between the two second openings. The above-mentioned second opening can be formed by, for example, a lithographic etching method, and its extension direction is perpendicular to the extension direction of the above-mentioned first opening, that is, parallel to the paper surface. The upper electrode is generally a reflective electrode that can move up and down through deformation, and is composed of the second conductive layer 250 . The material of the above-mentioned second conductive layer 250 can be metal, which must be able to reflect light incident from below the transparent substrate 200 .

In FIG. 2D , the sacrificial layer 225 is removed by a release etching process to complete the fabrication of the reflective interferometric modulation display element. The removal method available for the above-mentioned structure release process may be, for example, a remote plasma etching method. The precursor of the etching plasma used in the remote plasma etching method is a fluorine-based or chlorine-based etchant, such as xenon difluoride, carbon tetrafluoride, boron trichloride, nitrogen trifluoride, sulfur hexafluoride or any combination thereof.

It can be known from the above preferred embodiments of the present invention that the surface of the bottom electrode is covered with a silicon-free protective layer to separate the silicon-containing insulating layer from the sacrificial layer. Therefore, the etching selectivity ratio between the sacrificial layer and the protective layer is much greater than that between the sacrificial layer and the insulating layer in the prior art. Therefore, when removing the sacrificial layer, the surface of the lower electrode is not attacked by the etchant used. Therefore, the structure of the optical thin film of the bottom electrode can be kept intact, so that its properties are stable, so as to provide high-quality image display.

As mentioned above, for those of ordinary skill in the art, other various corresponding changes and modifications can be made according to the technical scheme and technical concept of the present invention, and all these changes and modifications should belong to the appended claims of the present invention scope of protection.

Claims (11)

1. A method for manufacturing a reflective interference adjustment display element, characterized in that the method at least includes: forming a first electrode layer on a transparent substrate, wherein the first electrode includes a first transparent conductive layer formed on the transparent substrate, a light absorbing layer formed on the first transparent conductive layer and a an insulating layer formed on the light absorbing layer; forming a protective layer on the first electrode layer; forming a sacrificial layer on the protection layer; Form at least two first openings in the form of straight strips in the sacrificial layer, the protective layer, and the first electrode layer to define at least one first electrode, and the first electrode is defined by the first electrode layer and the first electrode layer. the layer of protection is stacked; coating a photosensitive material on the transparent substrate, so that the photosensitive material fills the first openings and covers the sacrificial layer; patterning the photosensitive material so that the photosensitive material forms supports in the first openings; forming a second electrode layer on the sacrificial layer and the support; forming at least two second openings in the second electrode layer to define at least one second electrode, and the extension directions of the second openings and the extension directions of the first openings are perpendicular to each other; and The sacrificial layer is removed, wherein the protection layer protects the insulating layer from being damaged when the sacrificial layer is removed. 2. The method of manufacturing a reflective interference modulation display element according to claim 1, wherein the insulating layer comprises silicon oxide or silicon nitride. 3. The method of manufacturing a reflective interference modulation display element according to claim 1, wherein the material of the protective layer comprises metal oxide. 4. The method of manufacturing a reflective interference modulation display element according to claim 1, wherein the material of the protective layer comprises aluminum oxide, titanium oxide or tantalum oxide. 5. The method for manufacturing a reflective interference modulation display element according to claim 1, wherein the material of the sacrificial layer comprises polysilicon or amorphous silicon. 6. The method for manufacturing a reflective interferometric adjustment display element according to claim 1, wherein the method for removing the sacrificial layer comprises a remote plasma etching method. 7. The method for manufacturing a reflective interferometric display element according to claim 6, wherein the precursor of the etching plasma used in the remote plasma etching method is an etchant containing fluorine or chlorine. 8. The manufacturing method of reflective interference adjustment display element according to claim 7, wherein the precursor of the etching plasma used in the remote plasma etching method is selected from xenon difluoride, carbon tetrafluoride, trichloro A group consisting of boron trifluoride, nitrogen trifluoride, sulfur hexafluoride or any combination thereof. 9. A reflective interferometric adjustment display element, wherein the display element at least comprises: A first electrode, wherein the first electrode includes a first transparent conductive layer formed on the transparent substrate, a light absorption layer formed on the first transparent conductive layer, and a light absorption layer formed on the light absorption layer upper insulating layer; a second electrode arranged parallel to the first electrode; two supports located between the first electrode and the second electrode to form a chamber; and A protection layer, covering the surface of the first electrode facing the chamber, when etching the sacrificial layer between the first electrode and the second electrode, the protection layer is used to protect the surface of the first electrode from Damaged by etchant used. 10. The reflective interference modulation display element according to claim 9, wherein the material of the protective layer comprises metal oxide. 11. The reflective interference adjustment display element according to claim 9, wherein the material of the protective layer comprises aluminum oxide, titanium oxide or tantalum oxide.

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