Abstract:
A method for fabricating an interference display unit is provided. A first plate and a sacrificial layer are formed in order on a substrate and at least two openings are formed in the first plate and the sacrificial layer. A photoresist layer is spin-coated on the sacrificial layer and fills the openings. A photolithographic process patterns the photoresist layer to define a support with an arm. A second plate is formed on the sacrificial layer and posts. The arm&#39;s stress is released through a thermal process. The position of the arm is shifted and the distance between the first plate and the second plate is therefore defined. Finally, The sacrificial layer is removed.

Description:
FIELD OF INVENTION  
         [0001]    The present invention relates to a method for manufacturing an optical interference display. More particularly, the present invention relates to a method for manufacturing an optical interference display with posts of arms.  
         BACKGROUND OF THE INVENTION  
         [0002]    Planar displays are popular for portable displays and displays with space limits because they are light and small in size. To date, planar displays in addition to liquid crystal displays (LCD), organic electro-luminescent displays (OLED), plasma display panels (PDP) and so on, as well as a mode of the optical interference display are of interest.  
           [0003]    U.S. Pat. No. 5,835,255 discloses an array of display units of visible light that can be used in a planar display. Please refer to FIG. 1, which depicts a cross-sectional view of a display unit in the prior art. Every optical interference display unit  100  comprises two walls,  102  and  104 . Posts  106  support these two walls  102  and  104 , and a cavity  108  is subsequently formed. The distance between these two walls  102  and  104 , that is, the length of the cavity  108 , is D. One of the walls  102  and  104  is a semi-transmissible/semi-reflective layer with an absorption rate that partially absorbs visible light, and the other is a light reflective layer that is deformable when voltage is applied. When the incident light passes through the wall  102  or  104  and arrives in the cavity  108 , in all visible light spectra, only the visible light with the wavelength corresponding to the formula 1.1 can generate a constructive interference and can be emitted, that is,  
           2D=Nλ  (1.1)  
           [0004]    where N is a natural number.  
           [0005]    When the length D of cavity  108  is equal to half of the wavelength times any natural number, a constructive interference is generated and a sharp light wave is emitted. In the meantime, if the observer follows the direction of the incident light, a reflected light with wavelength λ 1  can be observed. Therefore, the display unit  100  is “open”.  
           [0006]    The first wall  102  is a semi-transmissible/semi-reflective electrode that comprises a substrate, an absorption layer, and a dielectric layer. Incident light passing through the first wall  102  is partially absorbed by the absorption layer. The substrate is made from conductive and transparent materials, such as ITO glass or IZO glass. The absorption layer is made from metal, such as aluminum, chromium or silver and so on. The dielectric layer is made from silicon oxide, silicon nitrite or metal oxide. Metal oxide can be obtained by directly oxidizing a portion of the absorption layer. The second wall  104  is a deformable reflective electrode. It shifts up and down by applying a voltage. The second wall  104  is typically made from dielectric materials/conductive transparent materials, or metal/conductive transparent materials.  
           [0007]    [0007]FIG. 2 depicts a cross-sectional view of a display unit in the prior art after applying a voltage. As shown in FIG. 2, while driven by the voltage, the wall  104  is deformed and falls down towards the wall  102  due to the attraction of static electricity. At this time, the distance between wall  102  and  104 , that is, the length of the cavity  108  is not exactly zero, but is d, which can be zero. If we use d instead of D in formula  1 . 1 , only the visible light with a wavelength satisfying formula 1.1, which is λ 2 , can generate a constructive interference, and be reflected by the wall  104 , and pass through the wall  102 . Because wall  102  has a high light absorption rate for light with wavelength λ 2 , all the incident light in the visible light spectrum is filtered out and an observer who follows the direction of the incident light cannot observe any reflected light in the visible light spectrum. The display unit  100  is now “closed”.  
           [0008]    Refer to FIG. 1 again, which shows that the posts  106  of the display unit  100  are generally made from negative photoresist materials. Refer to FIGS. 3A to  3 C, which depict a method for manufacturing a display unit in the prior art. Referring to FIG. 3A, the first wall  102  and a sacrificial layer  110  are formed in order on a transparent substrate  109 , and then an opening  112  is formed in the wall  102  and the sacrificial layer  110 . The opening  112  is suitable for forming posts therein. Next, a negative photoresist layer  111  is spin-coated on the sacrificial layer  110  and fills the opening  112 . The objective of forming the negative photoresist layer  111  is to form posts between the first wall  102  and the second wall (not shown). A backside exposure process is performed on the negative photoresist layer  111  in the opening  112 , in the direction indicated by arrow  113  to the transparent substrate  109 . The sacrificial layer  110  must be made from opaque materials, typically metal materials, to meet the needs of the backside exposure process.  
           [0009]    Refer to FIG. 3B, which shows that posts  106  remain in the opening  112  after removing the unexposed negative photoresist layer. Then, the wall  104  is formed on the sacrificial layer  110  and posts  106 . Referring to FIG. 3C, the sacrificial layer  110  is removed by a release etch process to form a cavity  114 . The length D of the cavity  114  is the thickness of the sacrificial layer  110 . Therefore, different thicknesses of the sacrificial layers must be used in different processes of the different display units to control reflection of light with different wavelengths.  
           [0010]    An array comprising the display unit  100  controlled by voltage operation is sufficient for a single color planar display, but not for a color planar display. A method in the prior art is to manufacture a pixel that comprises three display units with different cavity lengths as shown in FIG. 4, which depicts a cross-sectional view of a matrix color planar display in the prior art. Three display units  302 ,  304  and  306  are formed as an array on a substrate  300 , respectively. Display units  302 ,  304  and  306  can reflect an incident light  308  to color lights with different wavelengths, for example, which are red, green and blue lights, due to the different lengths of the cavities of the display units  302 ,  304  and  306 . It is not required that different reflective mirrors be used for the display units arranged in the array. More important is that good resolution be provided and the brightness of all color lights is uniform. However, three display units with different lengths of cavities need to be manufactured separately.  
           [0011]    Please refer to FIGS. 5A to  5 D, which depict cross-sectional views of a method for manufacturing the matrix color planar display in the prior art. In FIG. 5A, the first wall  310  and the first sacrificial layer  312  are formed in order on a transparent substrate  300 , and then openings  314 ,  316 ,  318 , and  320  are formed in the first wall  310  and the sacrificial layer  312  for defining predetermined positions where display units  302 ,  304 , and  306  are formed. The second sacrificial layer  322  is then conformally formed on the first sacrificial layer  312  and in the openings  314 ,  316 ,  318 , and  320 .  
           [0012]    Please referring to FIG. 5B, after the second sacrificial layer  322  in and between the openings  314  and  316 , and in the openings  318  and  320  is removed by a photolithographic etch process, the third sacrificial layer  324  is conformally formed on the first sacrificial layer  312  and the second sacrificial layer  322  and in the openings  314 ,  316 ,  318  and  320 .  
           [0013]    Please refer to FIG. 5C, which shows that the third sacrificial layer  324  in the openings  318  and  320  remains but the remainder of the third sacrificial layer  324  is removed by a photolithographic etch process. Next, a negative photoresist is spin-coated on the first sacrificial layer  312 , the second sacrificial layer  322 , and the third sacrificial layer  324 , and in the openings  314 ,  316 ,  318  and  320 , and fills the all openings to form a negative photoresist layer  326 . The negative photoresist layer  326  is used for forming posts (not shown) between the first wall  310  and the second wall (not shown).  
           [0014]    Please refer to FIG. 5D, which shows that a backside exposure process is performed on the negative photoresist layer  326  in the openings  314 ,  316 ,  318  and  320  in a direction of the transparent substrate  300 . The sacrificial layer  110  must be made at least from opaque materials, typically metal materials, to meet the needs of the backside exposure process. Posts  328  remain in the openings  314 ,  316 ,  318  and  320  after removing the unexposed negative photoresist layer  326 . Subsequently, the second wall  330  conformally covers the first sacrificial layer  312 , the second sacrificial layer  322 , the third sacrificial layer  324  and posts  328 .  
           [0015]    Afterward, the first sacrificial layer  312 , the second sacrificial layer  322 , and the third sacrificial layer  324  are removed by a release etch process to form the display units  302 ,  304 , and  306  shown in FIG. 4, wherein the lengths d1, d2, and d3 of three display units  302 ,  304 , and  306  are the thicknesses of the first sacrificial layer  312 , the second sacrificial layer  322 , and the third sacrificial layer  324 , respectively. Therefore, different thicknesses of sacrificial layers must be used in different processes of the different display units, to achieve the objective for controlling reflection of different wavelengths of light.  
           [0016]    There are at least three photolithographic etch processes required for manufacturing the matrix color planar display in the prior art, to define the lengths of the cavities of the display units  302 ,  304 , and  306 . In order to cooperate with the backside exposure for forming posts, metal materials must be used for making the sacrificial layer. The cost of the complicated manufacturing process is higher, and the yield cannot be increased due to the complicated manufacturing process.  
           [0017]    Therefore, it is an important subject to provide a simple method of manufacturing an optical interference display unit structure, for manufacturing a color optical interference display with high resolution, high brightness, simple process and high yield.  
         SUMMARY OF THE INVENTION  
         [0018]    It is therefore an objective of the present invention to provide a method for manufacturing an optical interference display unit structure, and the method is suitable for manufacturing a color optical interference display with resolution and high brightness.  
           [0019]    It is another an objective of the present invention to provide a method for manufacturing an optical interference display unit structure, and the method is suitable for manufacturing a color optical interference display with a simple and easy manufacturing process and high yield.  
           [0020]    It is still another objective of the present invention to provide a method for manufacturing an optical interference display unit structure, and the method is suitable for manufacturing a color optical interference display with posts.  
           [0021]    In accordance with the foregoing objectives of the present invention, one preferred embodiment of the invention provides a method for manufacturing an optical interference display unit structure. The first wall and a sacrificial layer are formed in order on a transparent substrate, and then an opening is formed in the first wall and the sacrificial layer. The opening is suitable for forming posts therein. Next, a photoresist layer is spin-coated on the sacrificial layer and fills the opening. A photolithographic process patterns the photoresist layer to define a support with an arm. The support and the arm are used for a post, and to define the length of the arm. Due to the exposure of the photoresist layer with the help of a mask, the sacrificial layer no longer must be opaque materials such as metal and the like; common dielectric materials are also used for making the sacrificial layer.  
           [0022]    The second wall is formed on the sacrificial layer and posts, and then baking is performed on the posts. The arm may generate displacement as the pivot of the support caused by stress action. An end of the arm adjacent to the support has less displacement, but another end of the arm has more displacement. The displacement of the arm may change the position of the second wall. Afterward, the sacrificial layer is removed by a release etch process to form a cavity, and the length D of the cavity may not be equal to the thickness of the sacrificial layer due to the displacement of the arm.  
           [0023]    The arms with the ratios of various lengths to thicknesses have various amounts of stress, and displacements and directions generated by arms are various during baking. Therefore, the arms with the ratios of various lengths to thicknesses may be used for controlling the length of the cavity, instead of the various thicknesses of the sacrificial layers used in the various processes of the display units to control various wavelengths of light reflected in the prior art. There are many advantages in the above way. First of all, the cost drops drastically. The thickness of the cavity in the prior art is the thickness of the sacrificial layer, and the sacrificial layer needs to be removed at the end of the process. However, using an upward displacement of the arms in the present invention increases the length of the cavity, so that the length of the cavity is greater than the thickness of the sacrificial layer, even if the thickness of the sacrificial layer is substantially decreased while forming the same length of cavities. Therefore, the material used for manufacturing the sacrificial layer is substantially reduced. The second, the process time is shortened. The release etch process of the metal sacrificial layer in the prior art consumes lots of time, because the sacrificial layer is removed by an etching gas that must permeate the spaces between the posts. The present invention utilizes a mask for a front exposure, so the sacrificial layer can be transparent materials such as dielectric materials, instead of opaque materials such as metal and the like as in the prior art. Besides, the thickness used by the sacrificial layer can be substantially reduced, so the time required for the release etch process can be also drastically decreased. Third, the color optical interference display formed by using posts can substantially reduce complexity of the process. The difference in the ratios of lengths to thicknesses of arms of posts is used for changing the stress of the arms. After baking, various optical interference display units have various lengths of the cavities due to the displacement of arms, such that reflected light is changed with various wavelengths, such as red, green, and blue lights, so as to obtain various color lights.  
           [0024]    In accordance with another an objective of the present invention, one preferred embodiment of the invention provides a method for manufacturing a matrix color planar display structure. Each matrix color planar display unit has three optical interference display units. The first wall and a sacrificial layer are formed in order on a transparent substrate, and then an opening is formed in the first wall and the sacrificial layer. The opening is suitable for forming posts therein. Next, a photoresist layer is spin-coated on the sacrificial layer and fills the opening. A photolithographic process patterns the photoresist layer to define a support with an arm. The support and the arm are used for a post, and to define the length of the arm. A single photolithographic process can accomplish the arms of three optical interference display units. Due to the exposure of the photoresist layer with the help of a mask, the sacrificial layer no longer must be an opaque material such as metal and the like; common dielectric materials are also used for making the sacrificial layer.  
           [0025]    The second wall is formed on the sacrificial layer and posts, and then baking is performed on the posts. The arm may generate displacement as the pivot of the support caused by stress action. An end of the arm adjacent to the support has less displacement, but another end of the arm has more displacement. The displacement of the arm may change the position of the second wall. Afterward, the sacrificial layer are removed by a release etching process to form a cavity, and the length D of the cavity may not be equal to the thickness of the sacrificial layer due to the displacement of the arm.  
           [0026]    The first wall is the first electrode, and the second wall is the second electrode. Each T-shaped arm of the optical interference display unit has variable length and stress. Therefore, after baking, each optical interference display unit has various cavity lengths due to the various displacements of arms, such that reflected light is changed with different wavelengths, such as red, green, and blue light. These in turn provide various color lights for a matrix color planar display structure.  
           [0027]    In accordance with the color planar display consisting of an array of optical interference display units disclosed by the present invention, the advantages of a matrix color planar display according to the prior art are retained, including high resolution and high brightness, as well as the advantages of a multi-layered color planar display with a simple process and high yield in the prior art. It is understood that the present invention discloses an optical interference display unit which not only keeps all advantages of the prior optical interference color planar display such as high resolution, high brightness, simple process and high yield during forming arrays, but also increases the window during processing and raises the yield of the optical interference color planar display.  
           [0028]    It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the invention as claimed.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    These and other features, aspects, and advantages of the present invention will be more fully understood by reading the following detailed description of the preferred embodiment, with reference made to the accompanying drawings as follows:  
         [0030]    [0030]FIG. 1 depicts a cross-sectional view of a display unit in the prior art;  
         [0031]    [0031]FIG. 2 depicts a cross-sectional view of a display unit in the prior art after applying a voltage;  
         [0032]    [0032]FIGS. 3A to  3 C depict a method for manufacturing a display unit in the prior art;  
         [0033]    [0033]FIG. 4 depicts a cross-sectional view of a matrix color planar display in the prior art;  
         [0034]    [0034]FIGS. 5A to  5 D depict cross-sectional views of a method of manufacturing a matrix color planar display in the prior art;  
         [0035]    [0035]FIGS. 6A to  6 C depict a method for manufacturing an optical interference display unit according to one preferred embodiment of this invention;  
         [0036]    [0036]FIG. 6D depicts a cross-sectional view of an optical interference display unit according to one preferred embodiment of this invention; and  
         [0037]    [0037]FIGS. 7A to  7 D depict a method of manufacturing a matrix color planar display structure according to the second preferred embodiment of this invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0038]    In order to provide more information of the optical interference display unit structure, the first embodiment is provided herein to explain the optical interference display unit structure in this invention. In addition, the second embodiment is provided to give further description of the optical interference color planar display formed with an array of the optical interference display unit.  
         [0039]    Embodiment 1  
         [0040]    [0040]FIGS. 6A to  6 C depict a method for manufacturing an optical interference display unit according to a preferred embodiment of the invention. Please referring to FIG. 6A first, a first electrode  502  and a sacrificial layer  506  are formed in order on a transparent substrate  501 . The sacrificial layer  506  is made of transparent materials such as dielectric materials, or opaque materials such as metal materials. An opening  508  is formed in the first electrode  502  and the sacrificial layer  506  by a photolithographic etch process. The opening  508  is suitable for forming a post therein.  
         [0041]    Next, a material layer  510  is formed in the sacrificial layer  506  and fills the opening  508 . The material layer  510  is suitable for forming posts, and the material layer  510  generally uses photosensitive materials such as photoresists, or non-photosensitive polymer materials such as polyester, polyamide or the like. If non-photosensitive materials are used for forming the material layer  510 , a photolithographic etch process is required to define posts in the material layer  510 . In this embodiment, the photosensitive materials are used for forming the material layer  510 , so merely a photolithographic etching process is required for patterning the material layer  510 .  
         [0042]    Please referring to FIG. 6B, the posts  512  are defined by patterning the material layer  510  during a photolithographic process. The post  512  has a support  514  disposed in the opening  508 , and the post  512  has arms  5121  and  5122 . The same photolithographic process also defines the lengths of arms  5121  and  5122 . The thicknesses of the arms  5121  and  5122  are decided in the step of forming the material layer  510 . A second electrode  504  is formed on the sacrificial layer  506  and the post  512 .  
         [0043]    Reference is next made to FIG. 6C. A thermal process is performed, such as baking. Arms  5121  and  5122  of the post  512  may generate displacement as the pivot of the support  514  caused by stress action. Ends of the arms  5121  and  5122  adjacent to the support  514  have less displacement, but other ends of the arms  5121  and  5122  have more displacement. The displacement of arms  5121  and  5122  may change the position of the second electrode  504 . Thereafter, the sacrificial layer  506  is removed by a release etch process to form a cavity  516 .  
         [0044]    The optical interference display unit made in FIGS. 6A to  6 C is shown in FIG. 6D, which depicts a cross-sectional view of an optical interference display unit of one preferred embodiment of this invention. An optical interference display unit  500 , which may be a color changeable pixel unit, at least comprises a first electrode  502  and a second electrode  504 . The first electrode  502  and the second electrode  504  are approximately parallel to each other. The first electrode  502  and the second electrode  504  are selected from the group consisting of narrowband mirrors, broadband mirrors, non-metal mirrors or the combination thereof.  
         [0045]    Posts  512  support the first electrode  502  and the second electrode  504 . The arms  5121  and  5122  of the posts  512  are raised upwards. The length of the cavity is the thickness of the sacrificial layer in the optical interference display unit structure in the prior art. If the thickness of the sacrificial layer is D, the length of the cavity is D, too. In this embodiment, a cavity  516  is formed between the first electrode  502  and the second electrode  504  supported by posts  512 . The posts  512  have the arms  5121  and  5122 . The ratio of lengths to thicknesses of the arms  5121  and  5122  decide stress thereof, and a dotted line  5121 ′ and a dotted line  5122 ′ label the positions prior to performing a thermal process of the arms  5121  and  5122 . After performing the thermal process, the arms  5121  and  5122  may generate displacement; therefore the position of the second electrode  504  changes from the original position labeled by the dotted line  504 ′, and the length D′ of the cavity  516  between the first electrode  502  and the second electrode  504  changes from the original length D. Since the length of the cavity  516  changes, the frequency of a reflected light changes following the length of the cavity  516 . In general, when posts  512  are made from polyamide compounds, the ratio of lengths to thicknesses of the arms  5121  and  5122  is from 5 to 50, and the length D′ of the cavity  516  is approximately 1.5 to 3 times the length D of the thickness of the sacrificial layer. Of course, the ratio of lengths to thicknesses of the arms  5121  and  5122  can be changed to make the length D′ of the baked cavity  516  smaller than the thickness of the sacrificial layer.  
         [0046]    In this invention, the materials suitable for forming posts  512  include positive photoresists, negative photoresists, and all kinds of polymers such as acrylic resins, epoxy resins and so on.  
         [0047]    Embodiment 2  
         [0048]    [0048]FIGS. 7A to  7 D depict a method for manufacturing a matrix color planar display structure according to the second preferred embodiment of this invention. Reference is made to FIG. 7A first, illustrating formation of the first electrode  602  and a sacrificial layer  604  in order on a transparent substrate  601 . The sacrificial layer  604  can be made of transparent materials such as dielectric materials, or opaque materials such as metal materials. Openings  606 ,  608 ,  610 , and  612  are formed in the first electrode  602  and the sacrificial layer  604  by a photolithographic etch process, and openings  606 ,  608 ,  610 , and  612  are suitable for forming posts therein.  
         [0049]    Next, a material layer  614  is formed on the sacrificial layer  604  and fills the openings  606 ,  608 ,  610 , and  612 . The optical interference display unit  624  is defined by openings  606  and  608 , the optical interference display unit  626  is defined by openings  608  and  610 , and the optical interference display unit  628  is defined by openings  610  and  612 . The material layer  614  is suitable for forming posts, and is generally made from photosensitive materials such as polyester or non-photosensitive materials such as polyester, polyamide or the like. If a non-photosensitive material is used for forming the material layer  614 , a photolithographic etching process is required to define posts on the material layer  614 . In this embodiment, the photosensitive material is used for forming the material layer  614 , so a single photolithographic etch process is sufficient for patterning the material layer  614 .  
         [0050]    Please refer to FIG. 7B. A photolithographic process patterns the first material layer  614 , so as to define posts  616 ,  618 ,  620 , and  622 . The posts  616 ,  618 ,  620 , and  622  have supports  6161 ,  6181 ,  6201 , and  6221  disposed in the openings  606 ,  608 ,  610 , and  612 , respectively. The posts  616 ,  618 ,  620 , and  622  also have arms  6162 ,  6182 ,  6183 ,  6202 ,  6203 , and  6222 . The arms  6162 ,  6182 ,  6183 ,  6202 ,  6203 , and  6222  are the same in length. A second electrode  630  is formed on the sacrificial layer  604 , posts  616 ,  618 ,  620 , and  622 .  
         [0051]    Please refer to FIG. 7C. A thermal process is performed, such as baking. The arms  6162 ,  6182 ,  6183 ,  6202 ,  6203 , and  6222  of the posts  616 ,  618 ,  620 , and  622  may generate displacement as the pivot of the supports  6161 ,  6181 ,  6201 , and  6221  caused by stress action. There is less displacement at the ends of the arms  6162 ,  6182 ,  6183 ,  6202 ,  6203 , and  6222  adjacent to the supports  6161 ,  6181 ,  6201 , and  6221 , but more displacement at the other ends of the arms  6162 ,  6182 ,  6183 ,  6202 ,  6203 , and  6222 . The displacements of the arms  6162  and  6182  are the same, the displacements of the arms  6183  and  6202  are the same, and the displacements of the arms  6203  and  6222  are the same. But there are various displacements among three above pairs of the arms. Therefore, there are various changes in the positions of the second electrode  630  caused by the arms  6162  and  6182 , the arms  6183  and  6202 , and the arms  6203  and  6222 .  
         [0052]    Thereafter, reference is made to FIG. 7D. The sacrificial layer  604  is removed by a release etch process to form the cavities  6241 ,  6261 , and  6281  of the optical interference display units  624 ,  626 , and  628 . The cavities  6241 ,  6261 , and  6281  have various lengths d 1 , d 2 , and d 3 , respectively. When the optical interference display units  624 ,  626 , and  628  are “open”, as shown as the formula 1.1, the design of lengths d 1 , d 2 , and d 3  of the cavities  6241 ,  6261 , and  6281  can generate the reflected light with different wavelengths, such as red (R), green (G), or blue (B) light.  
         [0053]    The lengths d 1 , d 2 , and d 3  of the cavities  6241 ,  6261 , and  6281  are not decided by the thickness of the sacrificial layer, but by the lengths of the arms  6162  and  6182 ,  6183  and  6202 ,  6203  and  6222 , respectively. Therefore, the complicated photolithographic process of the prior art to define various lengths of the cavities forming various thicknesses of the sacrificial layers is unnecessary.  
         [0054]    In accordance with the color planar display consisting of the array of optical interference display units disclosed by this embodiment, the advantages of a matrix color planar display in the prior art are retained, including high resolution and high brightness, as well as the advantages of the prior art multi-layered color planar display such as simple process and high yield. Compared with the matrix color planar display in the prior art, the embodiment discloses an optical interference display unit that does not require the complicated photolithographic process in the prior art to define various lengths of the cavities by forming various thicknesses of the sacrificial layers. The optical interference display unit thus has a simple process and high yield. Compared with the matrix color planar display in the prior art, the embodiment discloses an array of optical interference display units, in which all the optical interference display units that can generate reflected color light are located in the same plane. In other words, the incident light can reflect various color lights without passing through the multi-layered optical interference display unit; thus, the optical interference display unit has high resolution and high brightness. Furthermore, in the multi-layered optical interference display in the prior art, in order to make an incident light to pass through a former display unit and reach a latter display unit efficiently, and the result of light interference in the latter display unit (reflected light of green or blue light wavelength) to pass through a former display unit efficiently, the compositions and thicknesses of the first electrode and the second electrode of three types of display units are different. The manufacturing process is actually more complicated than expected. The process for the array of the optical interference display units disclosed by this invention is less difficult than the process in the prior art.  
         [0055]    Although the present invention has been described in considerable detail with reference certain preferred embodiments thereof, other embodiments are possible. Therefore, their spirit and scope of the appended claims should no be limited to the description of the preferred embodiments container herein. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.