JP2791435B2 - Liquid crystal display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to an active matrix type liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device in which the area of a transparent electrode for driving liquid crystal is substantially the same as the area of a matrix pixel opening. 2. Description of the Related Art In an active matrix type liquid crystal display device, a thin film transistor (hereinafter abbreviated as TFT) element (eg, FE) is used as a switching element.
FIG. 3 shows a schematic circuit when T) is used. [0005] The signal electrode wiring 3 and the scanning electrode wiring 6 are crossed and wired in a matrix, and the TFT element 2 is connected to each crossing point. That is, the source electrode of the TFT element 2 is connected to the signal electrode wiring 3, and the gate electrode is connected to the scanning electrode wiring 6. A liquid crystal element 9 is connected to the drain electrode of the TFT element 2.
0 electrode is connected. The other electrode of the liquid crystal element 90 is grounded. When a pixel signal is supplied to the signal electrode wiring 3 when one of the scanning electrode wirings 6 is selected, the TFT element 2 at the intersection of these two electrodes conducts. A pixel signal is applied to one electrode of the liquid crystal element 90 via the liquid crystal element 90, and the liquid crystal element 90 transmits light as one pixel. As described above, the transparent electrode for driving the liquid crystal of the conventional liquid crystal display pixel is one of Nikkei Electronics.
As described in the September 10, 984, pages 211 to 240, the TFT element and the electrode wiring portion have a gap corresponding to the alignment accuracy when patterning the transparent electrode on the electrode wiring portion. Was. Hereinafter, a conventional liquid crystal display device and a method of manufacturing the same will be briefly described with reference to FIG. FIG.
2A is a plan view showing one pixel of a conventional active matrix type liquid crystal display device, and FIG.
FIG. 3C is a sectional view taken along the line Y--Y in FIG. 3A. [0007] TFT elements 2 are formed in a matrix on a transparent substrate 1. The TFT element 2 includes a source region 21, a drain region 22, a channel region 23 between the source and the drain, and a gate electrode 24 stacked on the channel region 23 with a gate film interposed therebetween. The signal electrode arrangement 3 that is in conductive contact with the source region 21 is formed in the row direction by a photolithography method of exposing from the surface of the substrate 1. A (transparent) interlayer insulating film 4 is deposited on these, and T is deposited thereon by photolithography from the substrate surface.
After forming the contact hole 5 for the gate region 24 of the FT element 2, the scanning electrode wiring 6 in the column direction is formed. After a contact hole 8 for the drain region 22 is formed in the interlayer insulating film 4 by photolithography from the substrate surface, a transparent electrode material is deposited, and the transparent electrode 9 is similarly formed from the substrate surface by photolithography. Form. Although not shown, a liquid crystal is arranged on the transparent electrode 9 and a (transparent) opposing ground electrode is formed thereon. As described above, conventionally, necessary conductive materials and insulating films are sequentially deposited on the surface of the transparent substrate 1 and formed into a required pattern from the substrate surface by photolithography. In particular, in order to prevent the transparent electrode 9 from overlapping or contacting the signal electrode wiring 3 and the scanning electrode wiring 6, a gap A is formed between the transparent electrode 9 and the inner side of these electrode wirings in consideration of mask alignment accuracy. It was necessary to leave. [0010] The above-mentioned prior art is directed to a gap between a TFT element and a signal and a scanning electrode wiring in a matrix pixel opening and a transparent electrode for driving a liquid crystal (A in FIG. 2). That is, no consideration is given to the loss of the liquid crystal driving area with respect to the matrix pixel opening area, and the liquid crystal driving area ratio with respect to the pixel opening area is reduced by the mask rule (alignment accuracy). For this reason, the area which can be used as the light transmission of the liquid crystal cannot be completely used, so that the light transmission intensity and contrast are low and the interval between pixels is large, so that it is difficult to obtain a fine image. there were. An object of the present invention is to eliminate the gap between the liquid crystal driving electrode portion, the electrode wiring portion, and the TFT element portion so that the pixel opening area and the liquid crystal driving area are almost the same. It is to provide a device. The object of the present invention is to provide a resist for patterning a liquid crystal drive electrode portion by exposing a resist from the back surface of a substrate using a TFT element and an electrode wiring as a mask, and patterning the resist in a self-aligned manner. This is achieved by employing a structure. The TFT element, the signal, and the scanning electrode wiring do not transmit light and can serve as a resist mask when patterning the transparent electrode. Thus, the transparent electrode for driving the liquid crystal is patterned in a self-aligned manner by using a photolithography method by exposing from the back surface of the transparent substrate using the signal defining the TFT element and the pixel opening area and the scanning electrode wiring as a mask. Will be able to In this way, the transparent electrode can be patterned in all of the usable area of the pixel opening, and almost all of the pixel opening area can be effectively used as a liquid crystal driving part. FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described below. In FIG. 1, (a) is a plan view of one embodiment of the present invention, (b) is a cross-sectional view along the line XX, (c)
FIG. 4 is a sectional view taken along line YY in FIG. On the surface of the transparent substrate 1, a source region 21, a drain region 22, a channel region 23 between the source and the drain, and a gate electrode 24 laminated on the channel region 23 with a gate insulating film interposed therebetween.
The active matrix driving TFT element 2 is formed. On the transparent substrate 1 on which the TFT elements 2 are formed, signal electrode wirings (for example, Al) 3 in the row direction are provided.
Is formed so as to make conductive contact with the source region. Next, a transparent interlayer insulating film (for example, phosphor glass) 4 between the signal electrode wiring 3 and the scanning electrode wiring 6 to be formed later is deposited thereon by a normal pressure CVD method or the like. After this, T
After a contact hole 5 for connecting the gate region 24 of the FT element 2 and the scanning electrode wiring 6 is formed in the interlayer insulating film 4, the scanning electrode wiring (for example, Al) 6 in the column direction is formed by, for example, a photoresist method. Formed by Next, in order to avoid a short circuit between the liquid crystal driving transparent electrode 9 formed later and the already formed signal electrode wiring 3 and scanning electrode wiring 6, a transparent insulating film (for example, phosphor glass 7) is deposited by a normal pressure CVD method or the like. After that, the drain region 22 of the TFT element 2
And a transparent electrode for driving a liquid crystal to be formed later (for example, IT
O) A contact hole 8 with 9 is formed through the interlayer insulating film 4 and the transparent insulating film 7. Next, a transparent electrode material (for example, ITO) is attached to the entire surface by, for example, a sputtering method. Next, a negative photosensitive resist (resin) is applied thereon, and exposure is performed from the back surface of the substrate 1 using the TFT element 2 and the electrode wirings 3 and 6 as a mask. Then, the peripheral portion 1 of the contact hole 8
0 is re-exposed from the surface of the substrate 1 with an appropriate mask pattern to remove the non-exposed portion of the photosensitive resist, thereby exposing a transparent electrode material having a desired pattern as shown in FIG. . Next, the exposed portion of the transparent electrode material is removed with a solution (for example, aqua regia solution), and then the photosensitive resist in the exposed portion is removed, whereby the transparent electrode 9 can be completed. . Although not shown, the liquid crystal and the counter electrode are laminated on the transparent electrode 9 as in the conventional case. According to this embodiment, of the matrix pixel openings defined by the signal electrode wirings 3 and the scanning electrode wirings 6, the parts other than the TFT element 2 and its gate electrode lead part, in other words, The area which can be used as the light transmitting portion of the liquid crystal can be almost completely used. Thus, the light transmission intensity and the contrast can be increased, and the image quality can be improved by minimizing the gap between the pixels. Further, in practicing the present invention, it is not necessary to increase the number of photomasks used for manufacturing, and exposure of the peripheral portion 10 of the contact hole 8 does not require alignment accuracy, so that the process is simplified. Manufacturing efficiency and yield can be improved. According to the present invention, there is substantially no gap between the liquid crystal driving portion, the electrode wiring portion and the TFT element portion due to the alignment accuracy, so that the pixel opening area and the liquid crystal driving area are reduced. The areas are almost the same, and a high contrast ratio can be obtained as a liquid crystal display. Furthermore, image quality can be improved by minimizing the gap between pixels. Further, it is not necessary to increase the number of photomasks used for the manufacture, and the exposure of the peripheral portion 10 of the contact hole 8 does not require alignment accuracy. Yield can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view and a cross-sectional view of one pixel of an active matrix according to an embodiment of the present invention. FIG. 2 is a plan view and a cross-sectional view of one pixel of the related art. FIG. 3 is a general schematic circuit diagram of an active matrix type liquid crystal display device. [Description of Signs] 1 ... Transparent substrate, 2 ... TFT element, 3 ... Signal electrode wiring, 4
... interlayer insulating film, 5 ... contact hole, 6 ... scan electrode wiring,
7: transparent insulating film, 8: contact hole, 9: transparent electrode

Claims (1)

(57) [Claims] A thin film semiconductor element formed in a matrix on the surface of the transparent substrate; a gate electrode formed on a channel region of the thin film semiconductor element; and a source region of the thin film semiconductor element formed in a row direction. A connected signal electrode wiring, a first transparent insulating film formed on the thin film semiconductor element, the gate electrode, and the signal electrode wiring; and a first transparent insulating film formed on the first transparent insulating film in a row direction. First
A scanning electrode wiring connected to the gate electrode through a contact hole opened in the transparent insulating film, and a second transparent insulating film formed on the first transparent insulating film and the scanning electrode wiring. Formed on the second transparent insulating film, the contour of which is planar
And the inner side of the scanning electrode wiring and the signal electrode wiring.
A liquid crystal display device, comprising: a transparent conductive film that is in agreement with the drain region of the thin-film semiconductor element and penetrates a contact hole opened in the first and second transparent insulating films. 2. The transparent conductive film includes the thin film semiconductor element and each electrode.
Self-aligned by backside exposure using pole wiring as a mask
The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed. 3. The peripheral portion of a contact hole formed in the first and second transparent insulating films is formed by surface exposure using a photomask.
Liquid crystal display device according to. 4. 4. The liquid crystal display device according to claim 1, wherein the transparent conductive film is formed using a negative photosensitive resist.