JP3837951B2 - Electro-optical panel and electronic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of an active matrix drive type electro-optical panel using a thin film transistor (hereinafter referred to as TFT: Thin Film Transistor) and the like and an electronic device using the active matrix drive. In addition, the present invention belongs to the technical field of an electro-optical panel and an electronic apparatus using the same without causing a decrease in pixel aperture ratio.
[0002]
[Prior art]
Conventionally, in an electro-optical panel such as an active matrix driving type liquid crystal panel in which a plurality of pixel electrodes provided in a matrix are controlled by TFTs as switching elements, as shown in FIG. A plurality of TFTs 30 'and pixel electrodes 9a electrically connected to the TFTs via contact holes 8 are provided on the TFT array substrate corresponding to the scanning lines 3a and data lines 6a and their intersections. The configuration of each TFT 30 'is controlled by the gate electrode 3a' protruding from the scanning line 3a in the channel region 1a '(the left-upward hatched portion in FIG. 16) of the semiconductor layer 1a, and the data line 6a for supplying an image signal is connected to the contact hole 5 Are electrically connected to the source region of the semiconductor layer 1a, and the pixel electrode 9a is connected to the drain region of the semiconductor layer 1a. In particular, the pixel electrode 9a is provided on various films constituting the wiring such as the TFT 30 ′, the data line 6a, and the scanning line 3a, and an interlayer insulating film for insulating the pixel electrode 9a from each other. It is connected to the drain region of the TFT 30 ′ through a contact hole 8 opened in a film or the like.
[0003]
[Problems to be solved by the invention]
However, in the technical field of liquid crystal panels, in order to obtain high resolution image quality, there is an increasing demand for higher definition of pixels, and pixel pitch miniaturization is increasingly accelerated. Thus, in order to increase the pixel density so that a high-definition image can be displayed and to reduce the size of the liquid crystal panel, when the pixel pitch L is narrowed and miniaturized as shown in FIG. The distance between the various wirings forming the area is narrowed. Brightness is an important element of the liquid crystal panel, and this can be realized by increasing the pixel aperture ratio, which is the ratio of the pixel aperture area to the image display area. Since the region such as the line 3a and the TFT 30 ′ serving as a switching element is a non-opening region, there is a certain limit to increasing the pixel aperture ratio. Therefore, even if the pixels are miniaturized, in order to increase the pixel aperture ratio, the distance between the contact hole 8 for connecting the pixel electrode 9a and the TFT 30 'and the data line 6a or the scanning line 3a is also reduced. Therefore, there is a possibility that the pixel electrode 9a and various wirings are short-circuited to cause a fatal pixel defect.
[0004]
Further, it is important not only to reduce the wiring width of the data line 6a, the scanning line 3a, etc., but also to make the TFT 30 ′ as a switching element finer, and the contact hole 5 between the source region of the semiconductor layer 1a and the data line 6a. It is necessary to reduce the size of the contact hole 8 between the drain region and the pixel electrode 9a. FIG. 17 is a cross-sectional view taken along the line DD ′ of FIG. 16, that is, a cross-sectional view of the TFT 30 ′, and shows a process of opening the contact hole 8. In FIG. 17A, after forming the gate insulating film 2 and the interlayer insulating films 4 and 7 on the drain region 1e, the resist 302 is exposed from the photomask 303 as shown in FIG. 17B. Thus, in the case of a positive type resist, the portion of the resist 302 irradiated with light is exposed and the resist 302 is removed. However, the problem here is the level difference between the interlayer insulating films 4 and 7 by the gate electrode 3a ′. When the contact hole 8 is opened in the immediate vicinity of the gate electrode 3a ′ in order to reduce the size of the TFT 30 ′, the stepped portion causes irregular reflection of light by mask exposure, and in the direction of the arrow in the figure. There was a problem that the resist 302 was retracted. As a result, the portion without the light-shielding chromium film 304 on the photomask 303, that is, the pattern diameter from which the resist 302 is removed becomes larger than the pattern diameter for opening a contact hole, which is shown in FIG. When etching is performed, the hole diameter becomes larger than the pattern diameter for opening a contact hole formed on the photomask 303, and there is a problem that it is difficult to miniaturize the contact hole 8.
[0005]
Furthermore, under the demand for high-quality display images and energy saving in the technical field of liquid crystal panels, it is necessary to improve the light utilization efficiency using a microlens or the like, but like the conventional pixel shown in FIG. The light transmitting region is defined by the second light shielding film 22 formed on the counter substrate, and the inner side surrounded by the broken line is the light transmitting region. As in the conventional example described above, when the light transmitting region is not line symmetric with respect to the center of the pixel opening, the effect of the microlens cannot be maximized, and sufficient utilization efficiency of incident light is obtained. I can't.
[0006]
The present invention has been made in view of the above-described problems. By using a relatively simple configuration, an electro-optical panel that does not cause a decrease in process yield or pixel aperture ratio even when pixels are miniaturized, and the electro-optical panel. It is an object to provide an electronic device including the above.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, an electro-optical panel of the present invention includes a pair of substrates, a liquid crystal sandwiched between the pair of substrates, a plurality of data lines on one substrate of the pair of substrates, A plurality of scanning lines intersecting a plurality of data lines, a plurality of thin film transistors provided corresponding to the data lines and the scanning lines, and a matrix provided corresponding to the plurality of thin film transistors. A plurality of pixel electrodes are provided, and on the substrate, capacitance lines that respectively give predetermined storage capacitances to the pixel electrodes are provided substantially in parallel with the scanning lines, and the pixel electrodes are connected via contact holes. The contact hole is connected to a drain region of a semiconductor layer constituting the thin film transistor, and the contact hole is opened between a capacitor line and a scanning line adjacent to each other, and directly below the contact hole. A raised film made of a conductive film electrically connected to the drain region is provided under the drain region of the semiconductor layer constituting the thin film transistor, and the raised film is formed directly below the contact hole with the scanning line. It is provided in an island shape in a gap with the capacitor line.
[0008]
According to this electro-optical panel, the contact hole is etched by laying a raised film under the semiconductor layer of the TFT at a predetermined position where a contact hole for connecting the TFT as a switching element and the pixel electrode is opened. It is possible to prevent a pixel defect from occurring even if the semiconductor layer of the TFT is penetrated when forming a hole in the process. As a result, the semiconductor layer can be thinned, and high-speed writing characteristics can be obtained, so that an electro-optical panel with a high contrast ratio can be realized.
The raised film is electrically connected to the drain region of the semiconductor layer of the TFT as a switching element. Further, as the material of the raising film, a polysilicon film or a conductive film such as a refractory metal film such as W (tungsten), Ti (titanium), Cr (chromium), Mo (molybdenum), Ta (tantalum) or an alloy film thereof is used. By doing so, even when the contact hole is opened in the etching process, even if the contact hole penetrates the semiconductor layer, it is electrically connected, so that no pixel defect occurs.
[0009]
In the electro-optical panel, the contact hole may be formed at a substantially central position between a data line for supplying an image signal to the pixel electrode and a data line adjacent to the data line.
Since electrical conduction is obtained, pixel defects do not occur.
[0010]
According to this electro-optical panel, the position of the contact hole opened in the interlayer insulating film for connecting the drain region of the TFT as a switching element and the pixel electrode is provided, and the image signal is supplied to the corresponding pixel electrode. By opening the data line at a substantially central position between the data line and the adjacent data line, it is possible to prevent a short circuit between the data line and the pixel electrode. The pixel aperture ratio is not reduced.
[0015]
In the electro-optical panel, it is preferable that the raised film is provided at a position that does not overlap the scanning line and the capacitor line.
[0016]
According to this electro-optical panel, the raised film provided under the drain region of the semiconductor layer of the TFT and the scanning line and the capacitor line provided above the semiconductor layer via the gate insulating film are laid so as not to overlap. This means that the surface of the interlayer insulating film on the drain region of the semiconductor layer can be made almost flat. Thereby, a resist mask is formed in a region where the interlayer insulating film is not removed to form a contact hole in a predetermined region of the interlayer insulating film, but when this resist mask is exposed in a photolithography process, If the surface of the interlayer insulating film is planarized, the reflection of light on the film surface can be suppressed, and the resist does not recede, so that a contact hole can be formed substantially in accordance with the mask dimensions. Therefore, since the opening shape dimension of the contact hole does not spread, the yield due to pixel defects is not reduced. In addition, since the size of the contact hole can be reduced, the pixel can be reduced, and the electro-optical panel can be increased in definition and size.
[0017]
The electro-optical panel is characterized in that a film thickness of the raised film is substantially the same as a film thickness of the scanning line and the capacitor line.
[0018]
According to this electro-optical panel, it is possible to further flatten the surface of the interlayer insulating film on the drain region of the TFT by forming the film thickness of the raised film almost the same as the film thickness of the scanning line and the capacitance line. It becomes. As a result, the resist mask can be further prevented from receding, the contact hole can be further miniaturized, and the pixel can be further miniaturized, which is advantageous for high definition and miniaturization of the electro-optical panel. It is.
[0019]
Further, the electro-optical panel is characterized in that the opening region of each pixel has a plane shape that is line-symmetric with respect to the contact hole.
[0020]
According to this electro-optical panel, the contact hole that electrically connects the drain region of the TFT and the pixel electrode is opened at a position symmetrical with respect to the center line of the opening region of each pixel. A line-symmetric opening region located near the center in each pixel having a square planar shape arranged in a wide area can be taken.
The step of the pixel electrode around the contact hole is axisymmetric with respect to the opening region. Therefore, whether a clockwise liquid crystal is used or a counterclockwise liquid crystal is used, the ease of occurrence of liquid crystal alignment defects such as reverse tilt is almost the same. In other words, when one of the liquid crystals around one is used, it is possible to prevent a situation in which the alignment defect is remarkably generated, and it is practically convenient that either one of the liquid crystals can be equally employed. Also, the light utilization efficiency is improved as compared with the case where a contact hole is formed at the corner of each pixel and a non-symmetrical light irradiation region is formed in a non-axisymmetric opening region as in the conventional example shown in FIG. Is done.
[0021]
The electro-optical panel is preferably provided with a microlens at a position facing each pixel electrode so that the center of the lens is located at the center line of the opening region.
[0022]
According to this electro-optical panel, by adjusting the center point of the light irradiation area such as a circle by the micro lens to the center line of the opening area of the pixel, the ratio of the light irradiation area to the opening area is increased, Light utilization efficiency can be improved. As a result, a bright electro-optical panel can be realized even if the pixels are miniaturized.
[0023]
According to another aspect of the invention, an electronic apparatus includes the above-described electro-optical panel.
[0024]
According to this electronic apparatus, the electronic apparatus includes the above-described electro-optical panel of the present invention, and does not cause a decrease in yield even if the pixels are miniaturized, and the light irradiation area with respect to the opening area is wide. An electro-optical panel with improved light utilization efficiency enables bright and high-quality image display.
[0025]
Such an operation and other advantages of the present invention will become apparent from the embodiments described below.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a liquid crystal panel is used as an example of an electro-optical panel.
[0027]
(First embodiment of liquid crystal panel)
The configuration of the first embodiment of the liquid crystal panel will be described with reference to FIGS. FIG. 1 is an equivalent circuit diagram showing a plurality of pixels formed in a matrix that forms an image display area of a liquid crystal panel. 2 is a plan view showing a plurality of adjacent pixel groups on the TFT array substrate constituting the liquid crystal panel, and FIG. 3 is a cross-sectional view taken along line AA ′ in FIG. The structure of the TFT is shown. In FIG. 3, in order to make each layer and each member recognizable on the drawing, the scale is different for each layer and each member.
[0028]
First, as shown in FIG. 1, the plurality of pixels formed in a matrix that forms the image display area of the liquid crystal panel according to the present embodiment includes a TFT 30 for controlling the pixel electrode 9a to the pixel electrode 9a in a matrix. A plurality of data lines 6 a that supply image signals are electrically connected to the source of the TFT 30. Image signals to be written to the data lines 6a may be supplied line-sequentially in the order of S1, S2,..., Sn, or may be supplied for each group of a plurality of adjacent data lines 6a. Further, the scanning line 3a is electrically connected to the gate of the TFT 30, and the scanning signal is applied to the scanning line 31 in a pulse sequential manner in the order of G1, G2,... Gm at a predetermined timing. ing. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and the image signal supplied from the data line is written at a predetermined timing by closing the TFT 30 as a switching element for a certain period. An image signal of a predetermined level written in the liquid crystal through the pixel electrode 9a is held for a certain period with a counter electrode (described later) formed on a counter substrate (described later). The liquid crystal modulates light and enables gradation display by changing the orientation and order of the molecular group according to the applied voltage level. In the normally white mode, incident light cannot pass through the liquid crystal part according to the applied voltage. In the normally black mode, incident light passes through the liquid crystal part according to the applied voltage. Light that has a contrast corresponding to the image signal is emitted from the liquid crystal panel as a whole. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode. Thereby, the holding characteristics are further improved, and a liquid crystal panel with a high contrast ratio can be realized. As a method of forming the storage capacitor 70, it goes without saying that the capacitor line 3b, which is a wiring for forming a capacitor, may be provided, or a capacitor may be formed between the scanning line 3a in the previous stage. Yes.
[0029]
Next, the configuration of the first embodiment of the liquid crystal panel will be described.
[0030]
According to the first embodiment, the planar layout of the pixels constituting the image display area of the liquid crystal panel adopts a configuration as shown in FIG. That is, a plurality of pixel electrodes 9a provided in a matrix, a plurality of data lines 6a arranged in the X direction and extending in the Y direction, and a plurality of data electrodes 6a arranged in the Y direction, each extending along the X direction. A scanning line 3a extending in the direction is provided. Here, to form a channel region 1a of the semiconductor layer 1a constituting the TFT30 at the intersection of _{S X} th data line 6a and the scanning lines 3a '(FIG. 2 left-side up hatching portion), the source region of the TFT30 data line Electrical connection is made through the contact hole 5 under 6a. Further, the drain region of the semiconductor layer 1a extends to the immediate vicinity of the adjacent S _{X + 1-} th data line 6a to form a first storage capacitor electrode 1f for adding a capacitor to the pixel. Between the first storage capacitor electrode 1f and the capacitor line 3b, a storage capacitor is formed using a gate insulating film as a dielectric. The capacitor line 3b extends in the X direction along the scanning line 3a to the outside of the image display area. Further, if the first storage capacitor electrode 1f is formed by extending from the drain region of the semiconductor layer 1a in the same manner under the data line 6a of the self-stage, in the non-light transmission region of the liquid crystal panel called the wiring formation portion. Since the storage capacitor can be added efficiently, the ability to hold charges written in the pixels is improved, and a liquid crystal panel with a high contrast ratio can be realized. In FIG. 2, there is no problem even if the S _Xth and S _{X +} 1th relationships of the data line 6a are reversed.
[0031]
Here, a contact hole 8 for connecting the drain region of the semiconductor layer 1a and the pixel electrode 9a is provided between the scanning line 3a and the capacitor line 3b. This is because the region where the liquid crystal disclination occurs due to the step shape of the contact hole 8 is matched with the same region as the disclination caused by the lateral electric field generated between the adjacent pixel electrodes 9a, so that light shielding is conventionally required. The contact hole 8 can be effectively provided in the area that has not been obtained. Further, immediately below the contact hole 8, a polysilicon film as an etching stopper, W (tungsten), Ti (titanium), Cr (chromium), Mo (molybdenum), Ta ( A conductive raised film 13a such as a refractory metal film such as tantalum or an alloy film thereof may be provided. This is because when the contact hole 8 provided for electrically connecting the drain region of the semiconductor layer 1a and the pixel electrode 9a is opened in the etching process, even if it penetrates the semiconductor layer 1a, no fatal pixel defect occurs. Thus, the semiconductor layer 1a can be thinned, and there is an advantage that a semiconductor layer can be formed with improved transistor characteristics and less influence of photoelectric effect on light. In this case, at least a part of the raised film 13a is formed so as to surround the region where the contact hole 8 is formed, and the scanning line 3a and the capacitor line 3b are not overlapped with the raised film 13a. When the margin between the contact hole 8 and the scanning line 3a and the capacitor line 3b is small, as shown in FIG. 2, the conductive film is provided so that at least one of the scanning line 3a and the capacitor line 3b does not overlap the raised film 13a. The scanning lines 3a and the capacitor lines 3b may be recessed two-dimensionally (planar) along the defined area. Further, by providing the contact hole 8 at substantially the center between the adjacent S _Xth data line 6a and S _{X +} 1th data line 6a, the data line 6a and the pixel electrode 9a are short-circuited even if the pixel is miniaturized. Can be prevented, and fatal defects such as point defects and line defects due to TFT 30 defects can be greatly reduced.
[0032]
In the liquid crystal panel of the first embodiment, at least the channel region 1a ′ of the TFT 30 and the junction between the channel region 1a ′ and the source region and drain region are formed below the data line 6a, so that the incident light is directly transmitted. The channel region 1a ′ and the junction between the channel region 1a ′, the source region, and the drain region are not irradiated. Further, at least the channel region 1a ′ of the TFT 30 and the junction between the channel region 1a ′ and the source region and the drain region are not irradiated with W (tungsten) or Ti (titanium) below the TFT 30 via an interlayer insulating film. ), Cr (chromium), Mo (molybdenum), Ta (tantalum) or other high melting point metal film or an alloy film thereof, or a first light-shielding film 11a such as a polysilicon film is provided (the hatched portion in FIG. By adopting such a configuration, it is possible to prevent a leak current generated when the light transmitted through the pixel opening is reflected by the polarizing plate or the like and irradiates the TFT 30. This means that leakage current due to the photoelectric effect of the semiconductor layer 1a can be prevented even when strong light is incident in order to increase the light utilization efficiency, and is particularly effective for a liquid crystal panel for projector use. The first light-shielding film 11a is preferably supplied with a constant potential such as a ground potential in order to prevent deterioration of the transistor characteristics of the TFT 30. At this time, if it is connected to a constant potential line such as a power source supplied to a peripheral circuit provided outside the image display area, a dedicated external circuit connection terminal and a lead-out wiring are not required. Can be used effectively.
[0033]
FIG. 3 is a cross section taken along the line AA ′ of FIG. 2 and shows the structure of the TFT 30 and the storage capacitor 70 in a three-dimensional manner. The TFT 30 has an LDD (Lightly Doped Drain) structure, and includes a scanning line 3a including a gate electrode, a channel region 1a ′ of the semiconductor layer 1a in which a channel is formed by an electric field from the scanning line 3a, the scanning line 3a and the semiconductor. Insulating thin film 2 including a gate insulating film for insulating layer 1a, low concentration source region (source side LDD region) 1b and low concentration drain region (drain side LDD region) 1c of semiconductor layer 1a, high concentration source of semiconductor layer 1a A region 1d and a high concentration drain region 1e are provided. A data line 6a is connected to the high concentration source region 1d, and a corresponding one of the plurality of pixel electrodes 9a is connected to the high concentration drain region 1e. The low concentration source region 1b and the high concentration source region 1d and the low concentration drain region 1c and the high concentration drain region 1e are predetermined according to whether an n-type or p-type channel is formed in the semiconductor layer 1a, as will be described later. It is formed by doping n-type or p-type impurity ions at a concentration. An n-type channel TFT has an advantage of high operating speed, and is often used as a TFT 30 which is a pixel switching element. In this embodiment, in particular, the data line 6a is composed of a light-shielding conductive film such as a metal film such as Al or an alloy film such as metal silicide. Further, on the scanning line 3a, the insulating thin film 2, and the first interlayer insulating film 12, a contact hole 5 leading to the high concentration source region 1d and a contact hole 8 leading to the high concentration drain region 1e are respectively formed. An insulating film 4 is formed. The data line 6a is electrically connected to the high concentration source region 1d through the contact hole 5 to the high concentration source region 1d. Furthermore, on the data line 6a and the second interlayer insulating film 4, a third interlayer insulating film 7 in which a contact hole 8 to the high concentration drain region 1e is formed is formed. The pixel electrode 9a is electrically connected to the high concentration drain region 1e through the contact hole 8 to the high concentration drain region 1e. The above-described pixel electrode 9a is provided on the upper surface of the third interlayer insulating film 7 thus configured. Here, immediately below the contact hole 8, a high concentration drain region 1e of the semiconductor layer 1a and a conductive raised film 13a are provided below the high concentration drain region 1e. As a result, even when the high-concentration drain region 1e of the semiconductor layer 1a penetrates through etching when the contact hole 8 is opened, it is not a fatal defect because it is electrically connected by the lower raised film 13a. . Further, since the region where the contact hole 8 is opened should be as flat as possible, it is preferable that the scanning lines 3a, the capacitor lines 3b, and the raised film 13a have the same thickness. Further, as shown in FIG. 2, a raised film 13a is extended in the space between the scanning line 3a and the capacitor line 3b so as to form as flat a region as possible. By adopting such a configuration, there is no step on the surface of the interlayer insulating film below the pixel electrode 9a around the contact hole 8 and between the scanning line 3a and the capacitor line 3b. It is possible to reduce the region where the occurrence of the occurrence is as small as possible. Thereby, the pixel aperture ratio can be further increased.
[0034]
The TFT 30 preferably has an LDD structure as described above, but may have an offset structure in which impurity ions are not implanted into the low concentration source region 1b and the low concentration drain region 1c, or from a part of the scanning line 3a. It may be a self-aligned TFT in which impurity ions are implanted at a high concentration using the gate electrode as a mask to form the high concentration source region 1d and the high concentration drain region 1e in a self-aligned manner.
[0035]
Further, in the structure of the TFT 30 shown in FIG. 3, one of the two scanning lines 3a to which the same scanning signal is supplied via the insulating thin film 2 between the high concentration source region 1d and the high concentration drain region 1e of the TFT 30. A dual-gate TFT may be provided by providing a gate electrode composed of a portion so as to have a series resistance. Thereby, the leakage current of the TFT 30 can be reduced. Further, if the dual gate TFT has the above-mentioned LDD structure or offset structure, the leakage current of the TFT 30 can be further reduced and a high contrast ratio can be realized. Further, the dual gate structure can provide redundancy, greatly reduce pixel defects, and can realize high contrast ratio image quality because of low leakage current even at high temperature operation. Needless to say, three or more gate electrodes may be provided between the high concentration source region 1d and the high concentration drain region 1e of the TFT 30.
[0036]
Here, in general, the channel region 1a ′, the low concentration source region 1b, the low concentration drain region 1c, and the like of the semiconductor layer 1a generate current due to the photoelectric conversion effect of polysilicon when light enters, and the transistor of the TFT 30 Although the characteristics deteriorate, in this embodiment, since the data line 6a is formed of a light-shielding metal film such as Al so as to cover the scanning line 3a from above, at least the channel region 1a ′ of the semiconductor layer 1a and Light incident on the low concentration source region 1b and the low concentration drain region 1c (that is, light from the upper side in FIG. 3) can be effectively prevented. Further, as described above, since the first light shielding film 11a is provided on the lower side of the TFT 30, the return to at least the channel region 1a ′, the low concentration source region 1b, and the low concentration drain region 1c of the semiconductor layer 1a. Incidence of light (that is, light from the lower side in FIG. 3) can be effectively prevented.
[0037]
Further, as shown in FIG. 1, the pixel electrode 9a is provided with a storage capacitor 70, respectively. More specifically, the storage capacitor 70 includes a first storage capacitor electrode 1f extending from the high-concentration drain region 1e of the semiconductor layer 1a, an insulating thin film 2 as a dielectric film of the storage capacitor 70, a scanning line 3a, Through the second storage capacitor electrode made of a part of the capacitor line 3b formed by the same process, the second interlayer insulating film 4 and the third interlayer insulating film 7, and the second interlayer insulating film 4 and the third interlayer insulating film 7 And a part of the pixel electrode 9a facing the capacitor line 3b. Thus, since the storage capacitor 70 is provided with the insulating thin film 2 interposed between the first storage capacitor electrode 1f and the second storage capacitor electrode formed of a part of the capacitor line 3b, the duty ratio is small. However, high-definition display is possible. As shown in FIG. 2, the capacitor line 3b is provided substantially in parallel with the scanning line 3a. Further, as in the present embodiment, by providing the first light shielding film 11a under the first storage capacitor electrode 1f via the first interlayer insulating film 12, the first interlayer insulating film 12 functions as a dielectric film, The storage capacity 70 can be increased. Thereby, a liquid crystal panel with higher image quality can be realized.
[0038]
(Liquid crystal panel manufacturing process)
Next, a manufacturing process of the liquid crystal panel having the above configuration will be described with reference to FIGS. 4 to 6 are process diagrams showing each layer on the TFT array substrate side in each process corresponding to the AA ′ cross section of FIG. Further, FIG. 7 is a process diagram showing each layer on the TFT array substrate side corresponding to the BB ′ cross section of FIG. 2, and shows the process from (17) of FIG. 4 to 7, the scales are different for each layer and each member so that each layer and each member have a size that can be recognized on the drawing.
[0039]
First, a manufacturing process of a portion including the TFT 30 corresponding to the AA ′ cross section of FIG. 2 will be described with reference to FIGS.
[0040]
As shown in step (1) in FIG. 4, a TFT array substrate 10 such as a quartz substrate or hard glass is prepared. Here, the annealing is preferably performed in an inert gas atmosphere such as N ₂ (nitrogen) and at a high temperature of about 900 to 1300 ° C., and pre-processing is performed so that distortion generated in the TFT array substrate 10 in a high-temperature process performed later is reduced. Keep it. That is, the TFT array substrate 10 is heat-treated in advance at the same temperature or higher in accordance with the temperature at which the high temperature treatment is performed at the maximum temperature in the manufacturing process.
[0041]
Metals such as Ti (titanium), Cr (chromium), W (tungsten), Ta (tantalum), Mo (molybdenum), and Pb (lead), metal silicide, and the like are formed on the entire surface of the TFT array substrate 10 thus processed. The light-shielding film 11 having a thickness of about 100 to 500 nm, preferably about 200 nm, is formed by sputtering the metal alloy film. Note that the light-shielding film 11 does not have to be formed when it is used for an application in which an amount of light that does not cause crosstalk is incident.
[0042]
Subsequently, as shown in step (2), a mask corresponding to the pattern of the first light-shielding film 11a is formed on the formed light-shielding film 11 by photolithography, and the light-shielding film 11 is etched through the mask. As a result, the first light-shielding film 11a is formed. At this time, the first light shielding film 11a may be formed in an island shape, or may be formed in a stripe shape along the scanning line 3a or the data line 6a. Further, if the first light shielding film 11a is formed in a lattice shape as shown in FIG. 2, the resistance of the first light shielding film 11a can be reduced.
[0043]
Next, as shown in step (3), TEOS (tetra-ethyl ortho-silicate) gas, TEB (tetra-ethyl boat rate) is formed on the first light-shielding film 11a by, for example, normal pressure or low pressure CVD. ) Gas, TMOP (tetra-methyl-oxy-phosphate) gas, NSG (silicate glass film not containing boron or phosphorus), PSG (silicate glass film containing phosphorus), BSG (silicate glass containing boron) Film), a silicate glass film such as BPSG (a silicate glass film containing phosphorus and boron), a first interlayer insulating film 12 made of a silicon nitride film, a silicon oxide film, or the like. The film thickness of the first interlayer insulating film 12 is, for example, about 800 to 1500 nm.
[0044]
Next, as shown in step (4), the conductive film 13 is formed by low pressure CVD or sputtering. The conductive film 13 is made of a polysilicon film, a refractory metal such as W (tungsten), Ti (titanium), Cr (chromium), Mo (molybdenum), Ta (tantalum), or an alloy film thereof. The film thickness is preferably the same as that of a scanning line or a capacitor line formed in a later step. This advantage will be described later.
[0045]
Next, as shown in step (5), by performing a photolithography step, an etching step, and the like, an island-shaped raised film 13a is left immediately below the pixel electrode 9a and the drain region of the semiconductor layer 1a in a later step. . The raised film 13a is laid so that a contact hole for electrically connecting the pixel electrode 9a and the drain region of the semiconductor layer does not become defective even if it penetrates the semiconductor layer during etching. There is no problem even if it is laid directly under the contact hole 5 for electrical connection with the source region of the semiconductor layer.
[0046]
Next, as shown in step (6), monosilane gas, disilane gas, etc. at a flow rate of about 400 to 600 cc / min are placed on the raised film 13a in a relatively low temperature environment of about 450 to 550 ° C., preferably about 500 ° C. An amorphous silicon film is formed by the low pressure CVD used (for example, CVD at a pressure of about 20 to 40 Pa). Thereafter, an annealing process is performed in a nitrogen atmosphere at about 600 to 700 ° C. for about 1 to 10 hours, preferably 4 to 6 hours, so that the polysilicon film 1 has a thickness of about 50 to 200 nm, preferably Is solid-phase grown to a thickness of about 100 nm. At this time, when an n-channel TFT 30 is formed, impurity ions of group V elements such as Sb (antimony), As (arsenic), and P (phosphorus) may be slightly doped by ion implantation or the like. When the TFT 30 is a p-channel type, a group III element impurity ion such as B (boron), Ga (gallium), or In (indium) may be slightly doped by ion implantation or the like. Note that the polysilicon film 1 may be directly formed by a low pressure CVD method or the like without going through an amorphous silicon film. Alternatively, the polysilicon film 1 may be formed by implanting silicon ions into a polysilicon film deposited by a low pressure CVD method or the like to make it amorphous (amorphized) and then recrystallizing it by annealing or the like. Alternatively, the silicon nuclei may be solid-phase grown by annealing treatment by laser irradiation such as excimer laser.
[0047]
Next, as shown in step (7), an island-shaped semiconductor layer 1a having a predetermined pattern is formed by a photolithography process, an etching process, or the like. At this time, not only the channel region and the source / drain region serving as the switching elements, but also the region of the first storage capacitor electrode 1f serving as one electrode of the storage capacitor electrode for adding capacitance to improve the retention characteristics of the pixel. Are collectively formed.
[0048]
Next, as shown in step (8), the semiconductor layer 1a is thermally oxidized at a temperature of about 900 to 1300 ° C., preferably about 1000 ° C., so that a relatively thin thickness of about 10 to 50 nm is thermally oxidized. A film is formed, and a high-temperature silicon oxide film (HTO film) or silicon nitride film is further deposited to a relatively thin thickness of about 100 to 1000 angstroms by a low pressure CVD method or the like to form an insulating thin film 2 having a multilayer structure. Needless to say, the insulating thin film 2 functions as a gate insulating film of the TFT 30 and a dielectric film of the storage capacitor 70. As a result, the semiconductor layer 1a has a thickness of about 20 to 150 nm, preferably about 35 to 50 nm, and the gate insulating film 2 has a thickness of about 20 to 150 nm, preferably about The thickness is 30 to 100 nm. By shortening the high-temperature thermal oxidation time in this way, it is possible to prevent warpage due to heat, particularly when a large substrate of about 8 inches is used. However, the insulating thin film 2 having a single layer structure may be formed only by thermally oxidizing the polysilicon film 1. Alternatively, a silicon nitride film may be used in order to increase the breakdown voltage of the insulating thin film 2.
[0049]
Next, as shown in step (9) of FIG. 5, after depositing the polysilicon film 3 by a low pressure CVD method or the like, P (phosphorus) is thermally diffused to make the polysilicon film 3 conductive. Alternatively, a doped silicon film in which P ions are introduced simultaneously with the formation of the polysilicon film 3 may be used. As shown in step (10), scanning lines 3a and capacitor lines 3b having a predetermined pattern as shown in FIG. 8 are formed by a photolithography process using a mask, an etching process, and the like. The film thickness of the scanning line 3a is, for example, about 100 to 800 nm. At this time, by making the film thickness approximately the same as the film thickness of the raised film 13a, the opening shape of the contact hole can be prevented from expanding.
[0050]
However, the scanning line 3a may be formed from a refractory metal film such as W or Mo or a metal silicide film instead of the polysilicon film, or a combination of these metal film or metal silicide film and polysilicon film. You may form in a multilayer. In this case, if the scanning line 3a is arranged as a light-shielding film corresponding to a part or all of the region covered by the second light-shielding film 22 shown in FIG. Part or all of the film 22 can be omitted. In this case, in particular, there is an advantage that it is possible to prevent a decrease in the pixel aperture ratio due to a bonding deviation between the counter substrate 20 and the TFT array substrate 10.
[0051]
Next, as shown in step (11), when the TFT 30 is an n-channel TFT having an LDD structure, scanning is performed in order to first form the low concentration source region 1b and the low concentration drain region 1c in the semiconductor layer 1a. Using the line 3a as a diffusion mask, impurity ions 300 of group V elements such as P are doped at a low concentration (for example, P ions at a dose of 1 to 3 × 10 ¹³ / cm ² ). As a result, the semiconductor layer 1a under the scanning line 3a becomes a channel region 1a ′. Further, the semiconductor layer 1a under the capacitor line 3b becomes a first storage capacitor electrode 1f that forms the storage capacitor 70 using the insulating thin film 2 as a dielectric. Note that the resistance may be reduced by implanting P ions or the like in advance in the portion where the first storage capacitor electrode 1f is formed.
[0052]
Next, as shown in step (12), after forming the resist layer 302 on the scanning line 3a with a mask wider than the scanning line 3a in order to form the high concentration source region 1d and the high concentration drain region 1e. Similarly, impurity ions 301 of group V elements such as P are doped at a high concentration (for example, P ions are doped at a dose of 1 to 3 × 10 ¹⁵ / cm ² ). When the TFT 30 is a p-channel type, the region of the n-channel TFT 30 is covered with a resist to protect it, and the steps (11) and (12) are repeated again. At this time, in order to form the low concentration source region 1b and the low concentration drain region 1c and the high concentration source region 1d and the high concentration drain region 1e in the semiconductor layer 1a, impurity ions of a group III element such as B (boron) are introduced. Use to dope. When the LDD structure is used as described above, there is an advantage that the short channel effect can be reduced. For example, an TFT having an offset structure may be used without doping with low-concentration impurity ions, and an ion implantation technique using P ions, B ions, or the like using a gate electrode formed of a part of the scanning line 3a as a mask. Thus, a self-aligned TFT may be used.
[0053]
In parallel with these steps, a peripheral drive circuit having a complementary structure composed of an n-channel TFT and a p-channel TFT can be formed on the peripheral portion on the TFT array substrate 10. Thus, in the present embodiment, peripheral drive circuits such as a data line drive circuit and a scan line drive circuit can be formed in the same process when forming the TFT 30, which is advantageous in manufacturing.
[0054]
Next, as shown in step (13), a silicate glass such as NSG, PSG, BSG, or BPSG is used to cover the scanning lines 3a and the capacitor lines 3b by using, for example, normal pressure or reduced pressure CVD or TEOS gas. A second interlayer insulating film 4 made of a film, a silicon nitride film, a silicon oxide film or the like is formed. The film thickness of the second interlayer insulating film 4 is preferably relatively thick so as not to add capacitance between the wirings, and is preferably about 500 to 1500 nm.
[0055]
Next, as shown in step (14), after annealing is performed at about 1000 ° C. for about 20 minutes to activate the semiconductor layer 1a, the contact hole 5 for the data line 6a is formed by reactive ion etching, reactivity. It is formed by dry etching such as ion beam etching. At this time, opening the contact hole 5 by anisotropic etching such as reactive ion etching or reactive ion beam etching has an advantage that the opening shape can be made substantially the same as the mask shape. However, if the hole is formed by combining dry etching and wet etching, the contact hole 5 can be tapered, so that an advantage can be obtained that disconnection during wiring connection can be prevented. Also, a contact hole for connecting the scanning line 3 a to a wiring (not shown) can be opened in the second interlayer insulating film 4 by the same process as the contact hole 5.
[0056]
Next, as shown in step (15) of FIG. 6, a low-resistance metal such as light-shielding Al or a metal-containing film 6 such as metal silicide is formed on the second interlayer insulating film 4 by sputtering or the like. Deposit 100 to 800 nm thick, preferably about 300 nm.
[0057]
Next, as shown in step (16), the data line 6a is formed by a photolithography process, an etching process, or the like. If the etching process is performed by dry etching such as reactive ion etching or reactive ion beam etching, overetching can be suppressed, and there is an advantage that patterning can be performed with high accuracy according to the mask dimensions.
[0058]
Next, as shown in step (17), a silicate glass film such as NSG, PSG, BSG, BPSG or the like is nitrided using, for example, atmospheric pressure or reduced pressure CVD method or TEOS gas so as to cover the data line 6a. A third interlayer insulating film 7 made of a silicon film, a silicon oxide film or the like is formed. The film thickness of the third interlayer insulating film 7 should be relatively thick so that no capacitance is added between the data line 6a and the pixel electrode 9a formed in a later process, and is preferably about 500 to 1500 nm. Further, since the liquid crystal disclination may occur due to the step of the TFT 30 which is a wiring or a switching element, an organic film or SOG (instead of or in place of the silicate glass film constituting the third interlayer insulating film 7). A flat film may be formed by spin-coating a spin-on glass) or performing a CMP (Chemical Mechanical Polishing) process. By adopting such a configuration, it is possible to reduce the occurrence region of liquid crystal disclination as much as possible, and a high pixel aperture ratio can be realized even if the pixels are miniaturized.
[0059]
Next, as shown in step (18), a contact hole 8 for electrically connecting the pixel electrode 9a and the high concentration drain region 1e is formed by dry etching such as reactive ion etching or reactive ion beam etching. At this time, when the contact hole 8 is opened by anisotropic etching such as reactive ion etching or reactive ion beam etching, there is an advantage that the opening shape can be made substantially the same as the mask shape. However, if the hole is formed by combining dry etching and wet etching, the contact hole 8 can be tapered, so that an advantage of preventing disconnection at the time of wiring connection can be obtained. Further, not only the high-concentration drain region 1e of the semiconductor layer 1a but also the raised film 13a which is a conductive film is laid immediately below the opening region of the contact hole 8, so that even if it penetrates the semiconductor layer 1a, it is fatal. There will be no defects. Furthermore, since the channel region 1a ′ of the semiconductor layer 1a can be thinned by laying the raised film 13a, the characteristics of the element can be improved.
[0060]
Next, as shown in step (19), a transparent conductive thin film 9 such as an ITO (Indium Tin Oxide) film is deposited on the third interlayer insulating film 7 to a thickness of about 50 to 200 nm by sputtering or the like. Further, as shown in the step (20), the pixel electrode 9a is formed by a photolithography process, an etching process, or the like. When the liquid crystal panel is used in a reflective liquid crystal device, the pixel electrode 9a may be formed from an opaque material having a high reflectance such as Al. In this case, when the third interlayer insulating film 7 is formed, it is necessary to flatten it by a CMP process or the like so that the pixel electrode 9a has a mirror surface.
[0061]
Subsequently, after applying a coating liquid of polyimide-based alignment film on the pixel electrode 9a, the alignment film 23 shown in FIG. 3 is subjected to a rubbing process so as to have a predetermined pretilt angle and in a predetermined direction. Is formed.
[0062]
On the other hand, for the counter substrate 20 shown in FIG. 3, a glass substrate or the like is first prepared, and the second light shielding film 22 is formed through a photolithography process and an etching process after sputtering, for example, metal chromium. Further, the second light shielding film 22 may be formed of a metal material such as Cr, Ni (nickel), Al or the like, or a material such as a black resin in which carbon or Ti is dispersed in a photoresist. If a light shielding film is formed on the TFT array substrate 10, the opening area is defined on the TFT array substrate 10, so the second light shielding film 22 on the counter substrate is not necessary, and the TFT array substrate 10 and the counter substrate 20 are not required. The liquid crystal panel can be ignored and the transmittance does not vary.
[0063]
Then, the counter electrode 21 is formed by depositing a transparent conductive thin film such as ITO on the entire surface of the counter substrate 20 by sputtering or the like to a thickness of about 50 to 200 nm. Further, after the polyimide alignment film coating solution is applied to the entire surface of the counter electrode 21, the alignment film 23 is formed by performing a rubbing process in a predetermined direction so as to have a predetermined pretilt angle.
[0064]
Finally, the TFT array substrate 10 and the counter substrate 20 on which the respective layers are formed as described above have a predetermined diameter (for example, a diameter of about 1 to 6 μm) such that the alignment film 23 faces the glass fiber or glass. A gap material made of beads or the like is pasted by a sealing material mixed in a predetermined amount, and a liquid crystal formed by mixing a plurality of types of nematic liquid crystals, for example, is sucked into the space between both substrates by vacuum suction or the like. A liquid crystal layer 50 having a layer thickness is formed.
[0065]
Here, a manufacturing process when the contact hole 8 provided in the region sandwiched between the scanning line 3a and the capacitor line 3b is opened will be described. FIG. 7 is a cross-sectional view taken along the line BB ′ in FIG. 2. Step (a) in FIG. 7 matches step (17) in FIG. Further, the steps of FIGS. 7A to 7D will be described in comparison with FIGS. 17A to 17D of the conventional example.
[0066]
As shown in step (a) of FIG. 7, in the liquid crystal panel of this embodiment, the contact holes on the third interlayer insulating film 7 are obtained by making the film thicknesses of the scanning lines 3 a and the capacitor lines 3 b and the raised film 13 a substantially uniform. The region where the hole 8 is opened is made almost flat.
[0067]
Next, as shown in step (b) of FIG. 7, exposure is performed by a stepper apparatus or the like using a photomask 303. In the case where the resist 302 is a positive resist, a portion where the light-shielding chromium film 304 on the photomask 303 is not present (that is, a portion through which light is transmitted) is removed. The resist 302 on the third interlayer insulating film 7 has a flat region where the contact hole 8 is opened, and therefore there is no irregular reflection at the time of exposure, and there is no light-shielding chromium film 304 on the photomask 303, that is, the contact. The resist 302 can be removed with the same size as the hole opening pattern diameter. Accordingly, since the resist 302 does not recede as shown in FIG. 17B, which is a conventional example, a contact hole as designed can be formed. Thereby, even when the pixels are miniaturized, a liquid crystal panel having a high pixel aperture ratio can be realized without causing a decrease in yield.
[0068]
Next, as shown in step (c) of FIG. 7, the contact hole 8 is formed by anisotropic dry etching such as reactive ion etching or reactive ion beam etching, so that the opening diameter of the contact hole 8 is reduced. Try not to spread as much as possible. Even if wet etching is performed to form the side wall of the contact hole 8 in a tapered shape, the resist 302 does not recede as in the prior art, so that the opening diameter does not increase and a fine contact hole is opened. Can be perforated.
[0069]
Finally, as shown in step (d) of FIG. 7, if the pixel electrode 9a is provided, pixels in the image display area of the TFT array substrate can be formed.
[0070]
(Second embodiment of liquid crystal panel)
A second embodiment of the liquid crystal panel according to the present invention will be described with reference to FIGS. FIG. 8 is a plan view showing a plurality of adjacent pixel groups on the TFT array substrate constituting the liquid crystal panel, and FIG. 9 is a cross-sectional view taken along line CC ′ in FIG. The structure of the TFT is shown. In FIG. 9, in order to make each layer and each member recognizable on the drawing, the scale is different for each layer and each member. 8 and 9, the same components as those in FIGS. 2 to 7 are denoted by the same reference numerals, and the description thereof is omitted.
[0071]
In the second embodiment, the overall configuration of the liquid crystal panel is almost the same as that of the first embodiment shown in FIGS. 2 and 3, and the first light shielding film 11a is laid below the TFT 30 as shown in FIG. There is no difference. For example, in the case of a liquid crystal panel used for an application that does not require strong light incidence, such as a direct-view type liquid crystal panel, there is no need to lay the first light shielding film 11a.
[0072]
Accordingly, as shown in FIG. 9, when the first light shielding film 11a is not provided, the first interlayer insulating film 12 is formed when there is no protrusion on the surface of the TFT array substrate 10 and sufficient cleaning has been performed. There is no need to do. Thereby, the process of forming the 1st light shielding film 11a and the process of depositing the 1st interlayer insulation film 12 can be reduced. That is, since the steps (1) to (3) in FIG. 4 can be reduced, there is an effect in terms of manufacturing yield and cost.
[0073]
When the third interlayer insulating film 7 itself is formed as in the second embodiment or a planarizing film such as an organic film is formed on the third interlayer insulating film, the contact hole 8 is opened. Since the irregular reflection at the time of exposure in the photolithography process can be prevented, a fine contact hole 8 can be realized. With such a configuration, the film thickness of the raised film 13a does not have to be the same as the film thickness of the scanning line 3a or the capacitor line 3b.
[0074]
(3rd Embodiment of a liquid crystal panel)
A third embodiment of the liquid crystal panel according to the present invention will be described with reference to FIG. FIG. 10 is a plan view showing a plurality of adjacent pixel groups on the TFT array substrate constituting the liquid crystal panel.
[0075]
In the third embodiment, the overall configuration of the liquid crystal panel is substantially the same as that of the first embodiment shown in FIGS. 2 and 3, and is an example in which the pixel pitch L in the X direction is narrow. This is an embodiment of a liquid crystal panel that is one third of the pixel pitch L shown in the first embodiment, and that provides a color filter on the counter substrate to form one dot of data with three pixels. It can be used as a single-panel type liquid crystal projector or notebook personal computer display that uses only one liquid crystal panel with a color filter.
[0076]
Thus, when the pixel pitch L in the X direction is narrowed, the distance between the data lines 6a is narrowed, so that there is a high possibility that the pixel electrodes 9a are short-circuited via the data lines 6a and the contact holes 8. When the data line 6a is formed of an Al (aluminum) film, it becomes remarkably high. This is because, since the melting point of the Al film is low, the third interlayer insulating film 7 cannot be formed in a porous shape by high temperature processing. Therefore, the etching rate when opening the contact hole 8 is accelerated. In particular, when the wet etching is performed in order to taper the side wall of the opening, the opening diameter of the third interlayer insulating film 7 in the contact hole 8 tends to increase. Further, if the raised film 13a as an etching stopper is not provided as in the prior art, the dry etching alone has a low selectivity between the semiconductor layer 1a and the interlayer insulating film, and thus there is a risk of penetration, and it is necessary to use the wet etching together. Therefore, it was difficult to make the aperture diameter small.
[0077]
FIG. 11 is a graph showing transition of the pixel pitch L and the defect rate when the contact hole 8 is designed to be a 2 μm square and the wiring width of the data line 6a is 5 μm. FIG. 11A shows a liquid crystal panel manufactured by a conventional manufacturing process, and FIG. 11B shows a result of a liquid crystal panel manufactured by the manufacturing process of this embodiment. According to this, in the conventional example of (a), when the pixel pitch is 20 μm or less, the defect rate due to pixel defects increases rapidly. However, in this embodiment, the defect rate due to pixel defects does not increase unless the pixel pitch is 10 μm or less. Therefore, when the liquid crystal panel of this embodiment is used, even if the pixel is miniaturized and the aperture ratio is increased, the data line 6a, the scanning line 3a or the capacitor line 3b and the pixel electrode 9a are less short-circuited, and the semiconductor layer 1a. Since the contact hole 8 between the drain region and the pixel electrode 9a does not penetrate, the yield does not decrease.
[0078]
Further, when the distance between the contact hole 8 and the data line 6a is extremely close as in the third embodiment, the film thickness of the raised film 13a is set to be substantially the same as the film thickness of the data line 6a. A region where the interlayer insulating film on the data line 6a and the contact hole 8 are opened may be substantially flat. Even if such a configuration is adopted, it is possible to suppress an increase in the diameter of the contact hole 8 and to reduce the level difference, thereby reducing the liquid crystal disclination.
[0079]
Furthermore, according to the present embodiment, the contact hole 8 is opened at a position symmetrical with respect to the center line 9c (see FIGS. 2, 8, and 10) of the opening region. The step (see FIG. 3) of the pixel electrode 9a in the periphery is axisymmetric with respect to the opening region. This is especially effective when TN (Twisted Nematic) liquid crystal is used. For the liquid crystal layer 50, liquid crystal orientation such as reverse tilt is poor regardless of whether clockwise liquid crystal or counterclockwise liquid crystal is used. The ease of occurrence is almost the same. In other words, if either one of the liquid crystals is used, it is possible to prevent a situation in which the alignment defect is remarkably generated. The liquid crystal layer 50 is equally applied to the clockwise liquid crystal and the counterclockwise liquid crystal. It is practically convenient.
[0080]
As described above, according to the present embodiment, the pixel electrode 9a is connected to the drain of the TFT via the contact hole 8 formed at the corner of each pixel as in the conventional example shown in FIG. Compared with, the light utilization efficiency is improved. In particular, in the case of the present embodiment, the opening area has a rectangular shape close to a square, that is, a rotationally symmetric planar shape, so that the ratio of the light irradiation area such as a circle to the opening area increases, Utilization efficiency is improved. Needless to say, the opening region may be other rotationally symmetric shapes such as a circle, a regular dodecagon, a regular octagon, a regular hexagon, and a square. Further, in the present embodiment, as shown in FIG. 2, the width of the opening region in the X direction is defined by two adjacent data lines 6a, and the width of the opening region in the Y direction sandwiches the opening region. By defining the contact hole 8 in a space between the adjacent scanning line 3a and the capacitor line 3b without sandwiching the opening region, the image is defined by the adjacent scanning line 3a and the capacitor line 3b. The two-dimensional space of the display area can be used effectively. Therefore, the opening area can be more efficiently widened, and the light utilization efficiency is greatly improved.
[0081]
(Configuration of LCD panel)
In the liquid crystal panel using this embodiment, since the TFT 30 as a pixel switching element is a polysilicon (p-Si) type TFT, the pixel is driven on the TFT array substrate 10 in the same process when the TFT 30 is formed. A peripheral circuit can be formed. The overall configuration of such a peripheral circuit built-in type liquid crystal panel 100 will be described with reference to FIGS. 12 is a plan view of the TFT array substrate as viewed from the side of the counter substrate together with the components formed thereon. FIG. 13 is a cross-sectional view taken along the line HH ′ of FIG. 12 including the counter substrate. FIG.
[0082]
In FIG. 12, a light-shielding third light-shielding film 53 for defining an image display area is provided on the TFT array substrate 10, and a sealing material 52 is provided in parallel to the outside thereof. A data line driving circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region outside the sealing material 52, and the scanning line driving circuit 104 has two sides adjacent to the one side. It is provided along. Further, on the remaining side of the TFT array substrate 10, a plurality of wirings 105 are provided for connecting between the scanning line driving circuits 104 provided on both sides of the image display area. Note that the scanning line driver circuit 104 may be formed only on one side when signal delay of the scanning line does not matter. It goes without saying that the data line driving circuit 101 may be provided on both sides of the image display area. In addition, at least one corner of the counter substrate 20 is provided with a vertical conductive material 106 for electrically conducting between the TFT array substrate 10 and the counter substrate 20. As shown in FIG. 13, the counter substrate 20 having substantially the same contour as the sealing material 52 shown in FIG. 12 is fixed to the TFT array substrate 10 by the sealing material 52.
[0083]
The data line driving circuit 101 and the scanning line driving circuit 104 are electrically connected to the data line 6a and the scanning line 3a, respectively, via a relay wiring. The data line driving circuit 101 includes a shift register circuit for sequentially transferring start signals based on a clock signal, and controls the sampling circuit by the driving signals sequentially output from the data line driving circuit 101. Then, an image signal converted into a form that can be displayed immediately from a display information processing circuit (not shown) is supplied to the data line 6a through the sampling circuit. Further, the scanning line driving circuit 104 includes a shift register circuit for sequentially transferring the start signal based on the clock signal, and sequentially sends the scanning signal to the scanning line 3a in a pulse manner. In accordance with the scanning signal, the data line driving circuit 101 sends a signal voltage corresponding to the image signal to the data line 6a. The liquid crystal is controlled by the TFT 30 provided in each pixel portion corresponding to the intersection of the data line 6a and the scanning line 3a. Note that the sampling circuit may be formed in the data line driving circuit 101 or may be formed in the region of the third light shielding film 53. As described above, by forming the sampling circuit in the region of the third light shielding film 53 that was a dead space in the past, the space can be effectively used, and the data line driving circuit 101 can be downsized and highly functionalized. Can do.
[0084]
In FIG. 13, the liquid crystal layer 50 is made of, for example, a liquid crystal in which one kind or several kinds of nematic liquid crystals are mixed. The sealing material 52 is an adhesive made of, for example, a photocurable resin or a thermosetting resin for bonding the TFT array substrate 10 and the counter substrate 20 around them, and a distance between the two substrates (inter-substrate gap). A gap material (spacer) such as glass fiber or glass bead is mixed. Further, on the side of the counter substrate 20 facing the liquid crystal layer 50, a counter electrode 21 made of the second light shielding film 22 and an ITO film as a transparent conductive film is provided. Although not shown in FIG. 13, for example, a TN mode and an STN (super TN) mode are respectively provided on the side on which the incident light from the counter substrate 20 is incident and on the side on which the emitted light from the TFT array substrate 10 is emitted. Depending on the operation mode such as D-STN (double-STN) mode and normally white mode / normally black mode, a polarizing film, a retardation film, a polarizing plate and the like are arranged in a predetermined direction.
[0085]
Furthermore, in the liquid crystal panel 100, the liquid crystal layer 50 is composed of nematic liquid crystal as an example. However, if polymer dispersed liquid crystal in which liquid crystal is dispersed as fine particles in a polymer is used, the alignment film 23 and the above-described polarization are used. Films, polarizing plates and the like are not necessary, and the advantages of high brightness and low power consumption of the liquid crystal panel due to increased light utilization efficiency can be obtained. In addition, the present embodiment can be applied to various liquid crystal materials (liquid crystal phases), operation modes, liquid crystal alignments, driving methods, and the like. As described above, the liquid crystal panel of this embodiment can integrally form the peripheral circuit for driving the image display area on the TFT array substrate 10, and it is not necessary to externally attach the peripheral circuit by tape mounting or COG mounting. An ultra-small liquid crystal panel can be realized. In addition, the number of ICs for driving the liquid crystal panel can be greatly reduced, and a great advantage can be obtained in terms of cost.
[0086]
(Liquid crystal panel using microlenses)
The microlens 200 is formed by, for example, a manufacturing method disclosed in JP-A-6-194502. FIG. 14 shows an example, and after forming a film of a photosensitive material on the counter substrate 20, photopatterning is performed so that convex portions corresponding to the portions to be the lenses remain, and then the thermal deformation of the photosensitive material and An array pattern made of a photosensitive material having a smooth convex surface of each lens is formed on the counter substrate 20 by the surface tension, and then dry etching is performed using the array pattern of the photosensitive material as a mask to form the photosensitive material. By engraving the array pattern on the counter substrate 20, a microlens 200 having a convex surface of each lens smooth on the surface is formed. Alternatively, the microlens 200 may be formed by a so-called “thermal deformation method”.
[0087]
A cover glass 202 is attached to the entire surface of the microlens 200 with an adhesive 201, and a second light shielding film 22, a counter electrode 21, and an alignment film 23 are further formed thereon in this order. In this case, the second light shielding film 22 is provided in a matrix along the boundary of each microlens 200 so that the center of each opening overlaps the lens center 200 a of each microlens 200.
[0088]
In FIG. 14, the counter electrode 21 is formed over the entire surface of the counter substrate 20. Such a counter electrode 21 is formed by depositing an ITO film or the like to a thickness of about 50 to 200 nm by sputtering or the like, and then performing a photolithography process or an etching process. The alignment film 23 is made of, for example, an organic thin film such as a polyimide thin film. Such an alignment film 23 is formed, for example, by applying a rubbing process in a predetermined direction so as to have a predetermined pretilt angle after applying a polyimide-based coating liquid. The second light shielding film 22 is provided in a predetermined region facing the TFT 30. The second light shielding film 22 is formed by a sputtering process, a photolithography process, and an etching process using a metal material such as Cr or Ni, or a material such as a black resin in which carbon or Ti is dispersed in a photoresist. Is done. The second light-shielding film 22 has functions such as improving contrast and preventing color mixture of colors in addition to shielding the semiconductor layer 1 a of the TFT 30. Alternatively, as shown in FIG. 15, for example, a microlens 200 ′ configured by pasting a transparent plate (microlens array) on which the convex surface of each lens is formed in advance to the surface of the counter substrate 20 is provided on the counter substrate 20. It may be. Further, such a microlens may be attached to the surface of the counter substrate 20 facing the liquid crystal layer 50.
[0089]
In the present embodiment, in particular, as shown in FIGS. 2, 8, and 10, the opening region of the pixel electrode 9a has a line-symmetric shape with respect to the center line 9c passing through the center point 9b of the opening region. The contact hole 8 is opened at a position symmetrical with respect to the center line 9b of the opening region. Further, the microlens 200 (or 200 ′) has a lens center 200a (or 200a ′) at a position substantially opposite to the center point 9b.
[0090]
According to the present embodiment, when light is incident from the counter substrate 20 side, the microlens 200 (or 200 ′) having the lens center 200a (or 200a ′) at a position substantially opposite to the center point 9b (center of gravity) of the opening region. ), The incident light is collected on the pixel electrode 9a around the center point 9b of the opening region. Therefore, a circular (or substantially circular or elliptical) light irradiation region is formed in the opening region by the light collected by the microlens 200 (or 200 ′). Here, the contact hole 8 is opened at a position symmetrical with respect to the center line 9c of the opening region. For this reason, a line-symmetric opening region located near the center in each pixel can be widened. Since the opening area is line-symmetric with respect to the center line 9c passing through the center point 9b, the light irradiation area such as a circle is formed at a line-symmetric position in the line-symmetric opening area ( The center of a circle or the like almost overlaps the center point 9b). Accordingly, the ratio of the light irradiation area to the opening area is increased, and the light use efficiency is improved. Note that it is sufficient for the condensing capability of the microlens to be able to condense so that the light irradiation area is just within the opening area, and it is not necessary to make the light irradiation area smaller than necessary.
[0091]
In the present embodiment, the pixel electrode 9a is driven using a TFT. However, for example, an active matrix element other than a TFT, such as a TFD (Thin Film Diode), can be used. Furthermore, the liquid crystal panel can be configured as a passive matrix liquid crystal panel. Even in such a case, as long as the configuration for condensing the light on the pixel electrode by the microlens is adopted, the aperture region described in the present embodiment is set to be line symmetric or rotationally symmetric, and the lens center is substantially the aperture region. The configuration facing the center point is effective as in the case of this embodiment in improving the light utilization efficiency.
[0092]
(Electronics)
Next, an embodiment of an electronic apparatus including the liquid crystal panel according to this embodiment described in detail above will be described with reference to FIGS.
[0093]
First, FIG. 18 shows a schematic configuration of an electronic apparatus including the liquid crystal panel of the present embodiment.
[0094]
In FIG. 18, the electronic apparatus includes a display information output source 1000, a display information processing circuit 1002, a drive circuit 1004, a liquid crystal panel 100, a clock generation circuit 1008, and a power supply circuit 1010. The display information output source 1000 includes a ROM (Read Only Memory), a RAM (Random Access Memory), a memory such as an optical disk device, a tuning circuit that tunes and outputs an image signal, and the like. Based on this, display information such as an image signal in a predetermined format is output to the display information processing circuit 1002. The display information processing circuit 1002 includes various known processing circuits such as an amplification / polarity inversion circuit, a serial / parallel conversion circuit, a rotation circuit, a gamma correction circuit, and a clamp circuit, and is input based on a clock signal. Digital signals are sequentially generated from the displayed information and output to the drive circuit 1004 together with the clock signal CLK. The drive circuit 1004 drives the liquid crystal panel 100. The power supply circuit 1010 supplies predetermined power to the above-described circuits. A driving circuit 1004 may be mounted on the TFT array substrate constituting the liquid crystal panel 100, and in addition to this, a display information processing circuit 1002 may be mounted.
[0095]
Next, FIGS. 19 to 21 show specific examples of the electronic apparatus configured as described above.
[0096]
In FIG. 19, a liquid crystal projector 1100 as an example of an electronic device prepares three liquid crystal modules including the liquid crystal panel 100 in which the drive circuit 1004 described above is mounted on a TFT array substrate, and RGB light valves 100R and 100G, respectively. And as a projector used as 100B. In the liquid crystal projector 1100, when projection light is emitted from a lamp unit 1102 of a white light source such as a metal halide lamp, light components R, G, and R corresponding to the three primary colors of RGB are obtained by three mirrors 1106 and two dichroic mirrors 1108. B is divided into the light valves 100R, 100G and 100B corresponding to the respective colors. At this time, in particular, the B light is guided through a relay lens system 1121 including an incident lens 1122, a relay lens 1123, and an exit lens 1124 in order to prevent light loss due to a long optical path. The light components corresponding to the three primary colors modulated by the light valves 100R, 100G, and 100B are synthesized again by the dichroic prism 1112 and then projected as a color image on the screen 1120 via the projection lens 1114.
[0097]
In the present embodiment, in particular, when the light shielding film is provided on the lower side of the TFT as described above, the reflected light and the projection light by the projection optical system in the liquid crystal projector based on the projection light from the liquid crystal panel 100 pass. Reflected light from the surface of the TFT array substrate, part of the projected light (part of R light and G light) that penetrates the dichroic prism 1112 after being emitted from the other liquid crystal panel 100, etc. are returned as the TFT array. Even if the light is incident from the substrate side, it is possible to sufficiently shield the channel region such as a TFT for switching the pixel electrode. Therefore, even if a prism suitable for miniaturization is used in the projection optical system, an AR (Anti Reflection) film for preventing return light is attached between the TFT array substrate of each liquid crystal panel and the prism, or a polarizing plate. It is not necessary to perform an AR coating treatment on the surface, which is very advantageous in reducing the size and simplification of the configuration.
[0098]
Further, by adjusting the clear viewing directions of the liquid crystal panels constituting the three light valves 100R, 100G, and 100B, it is possible to suppress the occurrence of color unevenness and the reduction in contrast ratio. Therefore, when TN liquid crystal is used as the liquid crystal, only the light valve 100G needs to reverse the other light valves 100R and 100B and the clear viewing direction of the liquid crystal with respect to the image display area. Here, if the light valve provided with the liquid crystal panel according to the present embodiment is used, the shape of the pixel opening is almost the same on the left and right regardless of whether the TN liquid crystal is clockwise or counterclockwise. Even if a relationship occurs, it is recognized in the same way. As a result, when the light valves 100G, 100R, and 100B having different liquid crystal rotation directions are combined by a prism or the like, the display image does not cause color unevenness or a decrease in contrast ratio, thereby realizing a high-quality liquid crystal projector. .
[0099]
In FIG. 20, a laptop personal computer (PC) 1200 compatible with multimedia, which is another example of an electronic device, includes the above-described liquid crystal panel 100 in a top cover case, and further includes a CPU, a memory, a modem, and the like. And a main body 1204 in which a keyboard 1202 is incorporated.
[0100]
Further, as shown in FIG. 21, in the case of the liquid crystal panel 100 in which the driving circuit 1004 and the display information processing circuit 1002 are not mounted, an IC 1324 including the driving circuit 1004 and the display information processing circuit 1002 is mounted on the polyimide tape 1322. (Tape Carrier Package) 1320 can be physically and electrically connected to the periphery of the TFT array substrate 10 via an anisotropic conductive film to produce, sell, use, etc. as a liquid crystal device Is possible.
[0101]
In addition to the electronic devices described above with reference to FIGS. 19 to 21, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, an electronic notebook, a calculator, a word processor, an engineering workstation ( EWS), a mobile phone, a video phone, a POS terminal, a device provided with a touch panel, and the like are examples of the electronic device shown in FIG.
[0102]
As described above, according to the present embodiment, by using a relatively simple configuration, a liquid crystal panel that does not cause a decrease in process yield or pixel aperture ratio even when pixels are miniaturized, and various types of liquid crystal panels including the liquid crystal panel are provided. Can be realized. In this embodiment, the liquid crystal panel is used for description. However, the present invention is not limited to this, and the present invention can be applied to an electro-optical panel such as electroluminescence or a plasma display.
[0103]
【The invention's effect】
According to the liquid crystal panel of the present invention, the contact hole formed in the interlayer insulating film for connecting the drain region of the TFT as a switching element and the pixel electrode is provided, and the image signal is supplied to the corresponding pixel electrode. Can be prevented from being short-circuited between the data line and the data line adjacent to the data line, thereby preventing a short circuit between the data line and the pixel electrode. The yield is not reduced.
[Brief description of the drawings]
FIG. 1 is an equivalent circuit diagram of a pixel portion constituting an image display area of a liquid crystal panel.
FIG. 2 is a plan view of a plurality of adjacent pixel groups on the TFT array substrate in the first embodiment of the liquid crystal panel according to the present invention as viewed from the counter substrate side.
FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. 2 including the counter substrate.
FIG. 4 is a process diagram (part 1) illustrating a manufacturing process of an embodiment of a liquid crystal panel step by step with respect to the part illustrated in FIG. 3;
FIG. 5 is a process diagram (part 2) illustrating the manufacturing process of the embodiment of the liquid crystal panel step by step for the part illustrated in FIG. 3;
FIG. 6 is a process diagram (part 3) illustrating the manufacturing process of the embodiment of the liquid crystal panel step by step for the part illustrated in FIG. 3;
7 shows a manufacturing process of the embodiment of the liquid crystal panel along the BB ′ cross-sectional view of FIG. 2 in order of steps shown in steps (17) to (20) of FIG. 6 in further detail. FIG.
FIG. 8 is a plan view of a plurality of adjacent pixel groups on a TFT array substrate in a second embodiment of the liquid crystal panel according to the present invention, as viewed from the counter substrate side.
9 is a cross-sectional view taken along the line CC ′ of FIG. 8 including the counter substrate.
FIG. 10 is a plan view of a plurality of adjacent pixel groups on a TFT array substrate in a third embodiment of the liquid crystal panel according to the present invention as viewed from the counter substrate side.
FIG. 11 is a graph showing a pixel defect defect rate of a liquid crystal panel at a pixel pitch between a liquid crystal panel and a conventional liquid crystal panel in an embodiment of the liquid crystal panel according to the present invention.
FIG. 12 is a plan view showing an overall configuration of a liquid crystal panel according to the present invention.
13 is a cross-sectional view taken along line HH ′ of FIG.
FIG. 14 is an enlarged cross-sectional view of a counter substrate in a pixel portion where an example of a microlens is formed.
FIG. 15 is an enlarged cross-sectional view of a counter substrate in a pixel portion where another example of a microlens is formed.
FIG. 16 is a plan view of a plurality of adjacent pixel groups on a TFT array substrate in a conventional liquid crystal panel as viewed from the counter substrate side.
FIG. 17 is a process diagram showing the manufacturing process of a conventional liquid crystal panel in a step-by-step manner in more detail with respect to the processes shown in (17) to (20) of FIG. 6 along the DD ′ cross-sectional view of FIG. is there.
FIG. 18 is a block diagram showing a schematic configuration of an embodiment of an electronic apparatus according to the invention.
FIG. 19 is a cross-sectional view illustrating a liquid crystal projector as an example of an electronic apparatus.
FIG. 20 is a front view showing a personal computer as another example of the electronic apparatus.
FIG. 21 is a perspective view showing a liquid crystal device using TCP as an example of an electronic apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a ... Semiconductor layer 2 ... Insulating thin film 3a ... Scanning line 3a '... Gate electrode 3b ... Capacitance line 4 ... 2nd interlayer insulation film 5 ... Contact hole 6a ... Data line 7 ... 3rd interlayer insulation film 8 ... Contact hole 9a ... Pixel Electrode 10 ... TFT array substrate 11a ... first light shielding film 12 ... first interlayer insulating film 13a ... lifting film 20 ... counter substrate 21 ... counter electrode 22 ... second light shielding film 23 ... alignment film 30 ... TFT
50 ... Liquid crystal layer 52 ... Sealing material 53 ... Third light shielding film 70 ... Storage capacitor 101 ... Data line driving circuit 104 ... Scanning line driving circuit 200, 200 '... Micro lens 200a, 200a' ... Lens center 201 ... Adhesive

Claims (6)

A pair of substrates; a liquid crystal sandwiched between the pair of substrates; a plurality of data lines on one of the pair of substrates; a plurality of scanning lines intersecting the plurality of data lines; A plurality of thin film transistors provided corresponding to the lines and the scanning lines, and a plurality of pixel electrodes arranged in a matrix provided corresponding to the plurality of thin film transistors,
On the substrate, capacitance lines that respectively give a predetermined storage capacity to the pixel electrodes are provided substantially in parallel with the scanning lines,
The pixel electrode is connected to a drain region of a semiconductor layer constituting the thin film transistor through a contact hole,
The contact hole is opened at a substantially central position between a data line for supplying an image signal to the pixel electrode and a data line adjacent to the data line, and between adjacent capacitor lines and scanning lines. And
A raised film made of a conductive film electrically connected to the drain region is provided under the drain region of the semiconductor layer constituting the thin film transistor immediately below the contact hole,
The electro-optical panel, wherein the raised film is provided in an island shape in a gap between the scanning line and the capacitor line from directly below the contact hole.   The electro-optical panel according to claim 1, wherein the raising film is provided at a position that does not overlap the scanning line and the capacitance line.   3. The electro-optical panel according to claim 1, wherein a film thickness of the raised film is substantially the same as a film thickness of the scanning line and the capacitance line. 4.   4. The electro-optical panel according to claim 1, wherein the opening area of each pixel has a planar shape that is line-symmetric with respect to the contact hole. 5.   5. The electricity according to claim 1, wherein a microlens is provided at a position facing each pixel electrode so as to have a lens center at a center point of the aperture region of the pixel. Optical panel.   An electronic apparatus comprising the electro-optical panel according to claim 1.

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