JP2010066540A - Method for forming thin film for display element, and display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a thin film for a display element, by which a display region with high quality can be obtained by making the seam of a divided region hardly visible, while suppressing complication in the design of an exposure mask. <P>SOLUTION: Pixel electrodes 35 are formed in such a manner that electric characteristics of each pixel 24 randomly vary in the whole display region by exposing each division region obtained by dividing a corresponding region corresponding to the display region of a glass substrate by dividing lines intersecting each other, by using a reticle. Thus, the display region with good quality can be obtained by making seams of the division regions hardly visible, while suppressing complication in designing the reticle for exposure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin film forming method for a display element in which a thin film is formed in a display area of the display element, and a display element in which the thin film is formed in the display area.

  Conventionally, a liquid crystal display element as a display element, that is, a liquid crystal panel, has layers such as wiring such as scanning lines and signal lines, electrodes such as pixel electrodes, and switching elements such as thin film transistors on an array substrate. These include, for example, a film forming process for forming a thin film made of a conductor or a dielectric, a coating process for applying a photoresist on the thin film, and the applied photoresist through a mask having a predetermined pattern. Then, an exposure process for exposing, a developing process for developing the exposed photoresist, an etching process for removing the exposed thin film after removing the photoresist, and the like are repeated.

  There are masks for exposure used in the exposure process, such as the size of a glass substrate which is an insulating substrate used for an array substrate or the like, or a large mask of about 1/2 to 1/3 of the glass substrate size. Some of these masks (hereinafter referred to as reticles) are formed by performing a division exposure method. In such a case, since the size of the reticle is small with respect to the substrate, the pattern forming region is divided into a plurality of divided regions by dividing lines along the horizontal direction and the vertical direction, for example, and the photoresist of these divided regions is obtained. Are sequentially exposed through corresponding reticles.

  However, in the divided exposure as described above, a joint may be visually recognized at each boundary line. For this reason, the problem that the quality of the display screen displayed on a liquid crystal panel falls arises.

  One of the causes of such a seam being recognized is that a difference in pixel pattern characteristics occurs due to exposure deviation. For example, the capacitance value of the capacitance between the signal line constituting the pixel and the transparent electrode changes due to the exposure deviation, and the display characteristics change. Another cause is that the aperture ratio for each pixel changes due to different shots during exposure. Such a change in the aperture ratio occurs, for example, when the line width of the pattern changes or the aperture ratio changes depending on the relationship with other layers.

As a countermeasure for this, for example, a method is known in which the dividing line is formed in a zigzag shape so that the change gradient of the boundary characteristics is buffered to make it difficult to visually recognize the joint (for example, see Patent Document 1).
JP 2003-322864 A

  However, in the method described in the above-mentioned Patent Document 1, the pattern of the boundary line on the reticle is complicated, and in order to securely mesh the adjacent masks at the seam, a great deal of time is required for designing and inspecting the reticle. spend. For this reason, problems such as an increase in manufacturing cost occur.

  The present invention has been made in view of the above points, and it is possible to obtain a display area with good quality by making it difficult to visually recognize the joints of divided areas while suppressing the complexity of the design of an exposure mask. It aims at providing the thin film formation method for display elements, and a display element.

  The present invention is a thin film forming method for a display element, comprising a pair of substrates and forming a thin film on a display element on which a display region having a plurality of pixels is formed, wherein the display region of at least one of the substrates By exposing each corresponding region corresponding to 1 to each divided region divided by dividing lines intersecting each other using a mask, at least one layer of thin film is randomly generated in the entire display region. It is formed to vary.

  The present invention also provides a thin film forming method for a display element, comprising a pair of substrates and forming a thin film on a display element having a display region having a plurality of pixels, wherein the thin film is formed on at least one of the substrates. By exposing each corresponding region corresponding to the display region with a mask for each divided region divided by the dividing lines intersecting with each other, at least one thin film is formed, and the aperture ratio of each pixel is random over the entire display region. It is formed to vary.

  Furthermore, the present invention is a display element including a pair of substrates and having a display region having a plurality of pixels, wherein at least one of the substrates has the electrical characteristics of the pixels as the display. It has a thin film formed so as to vary randomly over the entire region.

  The present invention is a display element including a pair of substrates and having a display region having a plurality of pixels, wherein at least one of the substrates has an aperture ratio of each of the pixels in the display region It has a thin film formed so as to vary randomly as a whole.

  According to the present invention, by forming a thin film so that the electrical characteristics of each pixel randomly vary over the entire display area, it is possible to visually recognize the joints of the divided areas while suppressing the complexity of the design of the mask for exposure. This makes it difficult to obtain a display area with good quality.

  In addition, according to the present invention, by forming a thin film so that the aperture ratio of each pixel varies randomly in the entire display area, it is possible to suppress the complexity of the design of the mask for exposure and to reduce the joint of the divided areas. It becomes difficult to visually recognize and a display area with good quality can be obtained.

  The configuration of the first embodiment of the present invention will be described below with reference to the drawings.

  3 to 5, reference numeral 11 denotes a liquid crystal display device as a display device. The liquid crystal display device 11 is disposed on the back side of the liquid crystal panel 12 which is a liquid crystal display element as a display element. And a backlight 13 as a planar light source device that emits white light, and is a so-called transmission type that transmits and uses light from the backlight 13. In the following description, the liquid crystal panel 12 is described as a transmissive type. However, it is needless to say that the liquid crystal panel 12 is also applicable to a reflective type that reflects and uses external light, or a transflective type that uses a transmissive type and a reflective type. Absent.

  The liquid crystal panel 12 is an active matrix type liquid crystal panel capable of color display. An array substrate 15 as a first substrate and a counter substrate 16 as a second substrate are arranged to face each other, and light is transmitted between the substrates 15 and 16. A liquid crystal layer 17 serving as a modulation layer and a spacer that holds the gap constant are interposed, and a peripheral portion thereof is bonded to the adhesive layer 18. A plurality of pixels 24 each consisting of sub-pixels 23 of the same size are arranged in a matrix along each of a vertical direction (V direction) that is one direction and a horizontal direction (H direction) that is the other direction. In addition, a non-display area 25 as a light shielding portion is formed in a frame shape surrounding the display area 22. In addition, polarizing plates (not shown) are attached to the liquid crystal panel 12 on the display side of the array substrate 15 and the back surface (back surface) side of the counter substrate 16, respectively.

  The array substrate 15 has a glass substrate 30 as a first substrate body as an insulating substrate having translucency, for example, on the main surface of the glass substrate 30 on the liquid crystal layer 17 side (upper side in FIG. 3). As shown in FIG. 2, scanning lines (gate wirings) 31 that are a plurality of wirings and signal lines (source wirings) 32 that are a plurality of wirings are arranged in a grid pattern so as to be substantially orthogonal to each other. A thin film transistor (TFT) 33 as a switching element is provided at each crossing position of the scanning line 31 and the signal line 32, and an alignment film 34 for aligning liquid crystal molecules of the liquid crystal layer 17 is formed so as to cover them. ing.

  The scanning lines 31 and the signal lines 32 are thin films formed by members such as conductive metals. For this reason, the scanning line 31 and the signal line 32 do not transmit light. In other words, the scanning line 31 and the signal line 32 are light-shielding (reflecting), and are located between the pixels 24 to set an aperture ratio for each sub-pixel 23 (pixel 24). It functions as a wiring black matrix (BM) as setting means. The scanning lines 31 are formed along the horizontal direction (H direction), and the signal lines 32 are formed along the vertical direction (V direction).

  The thin film transistor 33 includes, for example, a semiconductor layer which is a thin film formed of amorphous silicon or polysilicon, a gate electrode which is a thin film, a source electrode and a drain electrode which are thin films electrically connected to the semiconductor layer, and these An insulating film, which is a thin film for insulation, is provided. The thin film transistor 33 has a gate electrode connected to the scanning line 31, a source electrode connected to the signal line 32, and a pixel electrode 35 which is a thin film as a transparent electrode forming the subpixel 23 on the drain electrode. Switching is controlled by applying a signal from the gate driver 36, which is a scanning line driving circuit, to the gate electrode via the scanning line 31, and the signal line 32 is transmitted from the source driver 37, which is a signal line driving circuit. By applying a voltage to the pixel electrode in response to a signal input via the sub-pixel 23, the sub-pixels 23 are turned on / off independently.

  Each pixel electrode 35 is formed in a substantially square shape using a transparent conductive material such as ITO (Indium Tin Oxide). Further, as shown in FIG. 1, these pixel electrodes 35 have a cutout portion 35a, which is a shape (area) changing portion of an arbitrary shape, in a part of the pixel electrode 35 at an arbitrary position such as the left side in the horizontal direction (H direction). For example, the electrical characteristics of the pixels 24 are set to vary randomly throughout the display region 22, that is, without having periodicity. In other words, each pixel electrode 35 is different from each other in a total area or a combination of shapes of a plurality of, for example, three subpixels 23 adjacent in the horizontal direction (H direction) constituting one pixel 24. Yes.

  Note that if the notch 35a is formed too large, the area of the sub-pixel 23 becomes unnecessarily narrow. Therefore, for example, a predetermined ratio or less, specifically, 10% or less with respect to the entire area of the pixel electrode 35. It is preferable to make it 1% to 4%.

  On the other hand, the counter substrate 16 has a glass substrate 51 as a second substrate body as a substrate having translucency, as shown in FIGS. 3 to 5, and a thin film as a colored layer is formed on the glass substrate 51. The color filter layer 52, the counter electrode 53, which is a thin film, the alignment film 54, which is a thin film for aligning liquid crystal molecules of the liquid crystal layer 17, and the like are sequentially stacked.

  As shown in FIG. 3, the color filter layer 52 includes colored portions 52r corresponding to a plurality of primary colors capable of forming white or black by color mixing, for example, red (R), green (G), and blue (B). 52g, 52b are provided, and the colored portions 52r, 52g, 52b are formed in stripes at portions corresponding to the display region 22. Further, a light shielding layer that sets an aperture ratio for each sub-pixel 23 (pixel 24) at a position between the colored portions 52r, 52g, and 52b of the color filter layer 52 and the entire outer periphery of the color filter layer 52. The aperture ratio setting means, ie, the black matrix layer 56 is formed as a thin film.

  Each of the colored portions 52r, 52g, and 52b is formed of, for example, a synthetic resin and has a size corresponding to the pixel electrode 35.

  The black matrix layer 56 is formed of, for example, a black synthetic resin having a light shielding property, and the pixel electrode 35 and the coloring portions 52r, 52g, and 52b when the counter substrate 16 is bonded to the array substrate 15 are combined. This is for preventing a plurality of coloring portions 52r, 52g, and 52b having different colors from overlapping each other on one pixel electrode 35 due to a slight misalignment or the like, thereby causing undesired color mixing in the sub-pixel 23.

  Next, the manufacturing method of the first embodiment will be described.

  When the liquid crystal panel 12 is manufactured, as shown in FIGS. 6 to 8, a plurality of layers corresponding to each liquid crystal panel 12 are provided at predetermined positions on a large glass substrate 61 as a large substrate for the array substrate 15 (see FIG. In FIG. 7, for example, six positions are formed, and each layer corresponding to each liquid crystal panel 12 is formed at a predetermined position on the large-sized glass substrate 62 as a large-sized substrate for the counter substrate 16. A plurality of corresponding (for example, six locations) are formed, and these large-sized glass substrates 61 and 62 are bonded together by the adhesive layer 18, and then the large-sized glass substrates 61 and 62 are cleaved at the position of each liquid crystal panel 12. The liquid crystal layer 17 may be obtained by dropping a liquid crystal material on one of the large-sized glass substrates 61 and 62 when the large-sized glass substrates 61 and 62 are bonded together, or by injecting the liquid crystal material after cleaving. .

  Each layer of each large-sized glass substrate 61, 62 includes, for example, a film forming process for forming a thin film, a coating process for applying a photoresist on the formed thin film, and a reticle R (a mask having a predetermined pattern on the applied photoresist). It is formed by repeating an exposure process for exposing via FIG. 8, a developing process for developing the exposed photoresist, an etching process for removing the exposed thin film after the photoresist is removed, and the like.

  On the large glass substrate 61 for the array substrate 15, wirings such as the scanning lines 31 and signal lines 32, electrodes such as the pixel electrodes 35, thin film transistors 33, and the like are formed. In addition, a color filter layer 52, a black matrix layer 56, a counter electrode 53, and the like are formed on a large glass substrate 62 for the counter substrate 16.

  For example, during the exposure process when forming each layer of the large glass substrate 61 for the array substrate 15, as shown in FIG. 7, the rectangular corresponding areas A corresponding to the display areas 22 of the liquid crystal panels 12 intersect each other. The dividing line, for example, a horizontal dividing line L1 that is a dividing line along the horizontal direction (H direction) and a vertical dividing line L2 that is a dividing line along the vertical direction (V direction) are divided into a plurality of, for example, four divided areas AD. The light is divided along a place where there is no influence on the upper surface, and divided exposure is performed using a reticle R (FIG. 8) designed for each divided area AD.

  In designing such a reticle R, CAD, which is a design program, is generally used. For example, in the case of a repetitive pattern such as sub-pixel 23, the CAD data structure is a part having a repetitive pattern by using a function of arranging one sub-pixel 23 in a matrix after designing one sub-pixel 23. Can greatly reduce the data.

  For example, the shape of the pixel electrode 35 (FIG. 1) is changed to process the reticle R so that the electrical characteristics of the pixel 24 vary over the entire display region 22. Here, if only a part of the pattern of the sub-pixels 23 arranged side by side in a matrix is to be changed, the entire matrix must be expanded and the amount of data becomes enormous. Preferably, the pattern is not changed, and only the pattern to be changed is added and created. That is, for example, after designing a pattern with the smallest area of the pixel electrode 35 and arranging this pattern in a matrix, the pattern to be added is randomly generated and overlaid on the pattern arranged in a matrix By adding a minute pattern, it is possible to apply random processing.

  In the exposure step, the reticle R processed as described above is sequentially arranged at a predetermined position on the large-sized glass substrate 61 using coordinate data called exposure data, and is exposed by an exposure machine. The exposure data includes the range of the exposure area on the reticle R and the data indicating the reference center point, the coordinate data on the large format glass substrate 61 to be exposed, and the like, and the specified range on the reticle R. Is exposed to a designated area on the large-sized glass substrate 61.

  As a result, as shown in FIG. 1, the shape (area) of the pixel electrode 35 varies for each pixel 24, so that the electrical characteristics of the pixel 24 vary randomly throughout the display region 22.

  The divided area AD is divided so that parts of the adjacent areas overlap each other, and multiple exposure is performed on the overlapping areas.

  As described above, according to the first embodiment, the pixel electrode 35 which is a thin film is formed so that the electrical characteristics of the pixels 24 randomly vary in the entire display region 22, specifically, the pixel electrode By forming the shape (area) of 35 so as to change for each pixel 24, the design of the reticle R for exposure is suppressed, and the seam in the divided area AD is difficult to visually recognize, and the display is of good quality. Region 22 can be obtained.

  As in the conventional example shown in FIG. 9B, when the divided reticle is exposed with straight line division, the straight line portion L may be recognized. At this time, the level visually recognized is a difference of a predetermined gradation of about 1 or 2 gradations when each of the sub-pixels 23 has, for example, 256 gradations. Therefore, in order to make it difficult to visually recognize the difference of about 1 or 2 gradations, there is a variation in gradation difference of 2 gradations to 25 gradations (preferably 3 gradations to 10 gradations). By designing the pattern of the pixel electrode 35 of the sub-pixel 23 as described above, it becomes difficult to recognize the seam at the portion corresponding to the straight line portion L in FIG. 9B, as shown in FIG. Here, in FIG. 9, for the sake of convenience, the left-right gradation difference and the random gradation variation of the straight line portion L are highlighted.

  In the first embodiment, the variation in the shape (area) of the pixel electrode 35 is changed for each pixel 24. However, for example, the pixel electrode 35 may be formed so as to change for each sub-pixel 23. Alternatively, it may be formed so as to be changed for each of the plurality of sub-pixels 23 or for each of the plurality of pixels 24.

  In addition, the shape (area) changing portion formed in a part of the pixel electrode 35 may be not only the notch 35a but also a protruding portion, for example.

  Furthermore, if the electrical characteristics of the sub-pixels 23 can be varied randomly throughout the display area 22, the pixel electrodes 35 are not limited to the thin film forming the thin film transistor 33, the scanning line 31, or the signal line 32, for example. Even if the pattern shape of at least one of the thin films is changed for each pixel 24, the same effect can be obtained.

  The color filter layer 52 is not limited to be formed on the counter substrate 16 side, and may be formed on the array substrate 15 side, for example. In this case, it is possible to adopt a configuration in which the black matrix layer 56 is not formed except for a predetermined region such as the periphery of the display region 22.

  Next, a second embodiment will be described with reference to FIG. In addition, about the structure and effect | action similar to the said 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In the second embodiment, the shape (area) of the black matrix layer 56 of the counter substrate 16 is changed for each pixel 24 instead of the configuration in which the shape of the pixel electrode 35 in the first embodiment is randomly varied. By varying the aperture, the aperture ratio of the pixels 24 varies randomly throughout the display area 22.

  That is, as shown in FIG. 10, by forming a protruding portion 56a which is a shape (area) changing portion of a different shape on the right side of the black matrix layer 56, for example, in the horizontal direction (H direction), the aperture ratio of the pixel 24 is formed. Are different from each other. In other words, the black matrix layer 56 is different from each other in a total area or a combination of shapes of a plurality of, for example, three subpixels 23 adjacent in the horizontal direction (H direction) constituting one pixel 24. Yes.

  If the protruding portion 56a is formed too large, the aperture ratio of the sub-pixels 23 becomes unnecessarily small. For example, the area of the sub-pixel 23 is less than a predetermined ratio, specifically, 10%. %, More preferably about 1% to 4%.

  Then, during the exposure process when forming each layer of the large glass substrate 62 for the counter substrate 16, as shown in FIG. 6, the rectangular corresponding areas A corresponding to the display areas 22 of the respective liquid crystal panels 12 cross each other. A plurality of, for example, four divided areas AD, including a horizontal dividing line L1 that is a dividing line along the horizontal direction (H direction) and a vertical dividing line L2 that is a dividing line along the vertical direction (V direction) The exposure is divided along a place where there is no influence on the characteristics, and divided exposure is performed using the reticle R designed corresponding to each divided area AD.

  Here, the reticle R is processed to vary the aperture ratio of the pixels 24 over the entire display area 22 by changing the shape of the black matrix layer 56 as in the first embodiment. In this processing, for example, after designing a pattern having the smallest area of the black matrix layer 56 and arranging this pattern in parallel, a pattern to be added is randomly generated and superimposed on the arranged pattern, thereby changing the amount of change. It is possible to apply random processing by simply adding a pattern.

  Then, the reticle R processed in this way is sequentially arranged at a predetermined position on the large-sized glass substrate 62 using the exposure data, and is exposed by an exposure machine.

  In this way, the black matrix layer 56 that is a thin film is formed so that the respective aperture ratios of the pixels 24 randomly vary over the entire display region 22, and specifically, the shape (area) of the black matrix layer 56 is changed for each pixel 24. By forming it so as to change, it is possible to obtain a display area 22 with good quality by making it difficult to visually recognize the joint in the divided area AD while suppressing the complexity of the design of the reticle R for exposure.

  In the second embodiment, the shape (area) changing part formed in a part of the black matrix layer 56 may be not only the protruding part 56a but also a notch part, for example.

  Further, if the aperture ratio of the sub-pixels 23 can be varied randomly throughout the display area 22, not only the black matrix layer 56, but also, for example, a light-shielding pattern shape by the colored portions 52r, 52g, and 52b of the color filter layer 52, or Similar effects can be obtained even if the shape of the light-shielding pattern formed by the scanning lines 31 and the signal lines 32 on the array substrate 15 side is changed for each sub-pixel 23.

  Further, in each of the above embodiments, the dividing line dividing the corresponding area A into the divided areas AD is not limited to being along the horizontal direction and the vertical direction, but can be any linear dividing line that intersects each other. It is.

  As the display element, not only the liquid crystal panel 12, but also any display element including a pair of substrates, such as an organic EL display element, can be similarly handled.

It is a top view which expands and shows the thin film of the display area of the display element of the 1st Embodiment of this invention. It is a circuit diagram which shows a display element same as the above. It is explanatory sectional drawing which shows a display element same as the above. It is a top view which shows a display element same as the above. It is explanatory drawing which shows the display apparatus provided with the display element same as the above. It is a top view which shows one side of the large format board | substrate of the manufacturing method of a display element same as the above. It is sectional drawing which shows the state which bonded the large format board same as the above. It is a top view which shows the mask for exposure of the thin film of a display element same as the above. (a) is an explanatory view showing the display state in the display region in a state where the pixel characteristics of the display element are randomly dispersed, and (b) shows the display state in the display region of the conventional display element. It is explanatory drawing. It is a top view which shows the positional relationship of the colored layer and light-shielding part of the display element of the 2nd Embodiment of this invention.

Explanation of symbols

12 Liquid crystal panels as display elements
22 Display area
24 pixels
30, 51 Glass substrate as substrate
35 Thin film pixel electrodes
56 Thin black matrix layer A Corresponding area
AD split region
Horizontal dividing line that is L1 dividing line
L2 dividing line, vertical dividing line R mask, reticle

Claims (8)

A thin film forming method for a display element, comprising a pair of substrates and forming a thin film on a display element in which a display region having a plurality of pixels is formed,
Exposing at least one thin film to each of the pixels by exposing each corresponding region corresponding to the display region of at least one of the substrates by a dividing region divided by dividing lines intersecting each other. A thin film forming method for a display element, characterized in that the electrical characteristics are randomly varied over the entire display region. The thin film forming method for a display element according to claim 1, wherein the characteristics of each of the pixels are varied by changing a pattern shape of the thin film for setting an electrical characteristic of the pixel for each pixel. A thin film forming method for a display element, comprising a pair of substrates and forming a thin film on a display element in which a display region having a plurality of pixels is formed,
Exposing at least one thin film to each of the pixels by exposing each corresponding region corresponding to the display region of at least one of the substrates by a dividing region divided by dividing lines intersecting each other. A thin film forming method for a display element, characterized in that the aperture ratio is randomly varied over the entire display region. 4. The thin film forming method for a display element according to claim 3, wherein the aperture ratio of each of the pixels is randomly varied by changing a light shielding pattern shape of the thin film constituting the pixel for each pixel. 5. A display element comprising a pair of substrates and having a display region having a plurality of pixels,
At least one of the substrates has a thin film formed such that the electrical characteristics of the pixels vary randomly over the entire display region. The display element according to claim 5, wherein the thin film has a different pattern shape for each of the pixels. A display element comprising a pair of substrates and having a display region having a plurality of pixels,
At least one of the substrates has a thin film formed so that the aperture ratio of each of the pixels varies randomly throughout the display area. The display element according to claim 7, wherein the thin film has a light shielding pattern shape different for each pixel.