JP2007272212A - Liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of inexpensively forming pixel gaps each of which has a size less than the limit of patterning based on photolithography. <P>SOLUTION: The liquid crystal display device comprising a semiconductor substrate 24 on which a plurality of reflection type pixel electrodes 10 arrayed like a matrix with prescribed pixel gaps 20 are formed through an insulating layer, a transparent substrate 26 on which a transparent electrode 26 opposed to the pixel electrodes 10 through a prescribed gap is formed, and liquid crystal 28 with which the gap is filled is provided with: patterning films 90 formed on respective pixel electrodes 10 through a gap whose size is wider than the size of the pixel gap; and sidewalls 94 formed through a gap of almost the same size as the pixel gap on a position corresponding to the pixel gap on the peripheral parts of respective patterning films 90 so as to surround the peripheries of respective patterning films 90. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly, a liquid crystal display device capable of expanding an effective area of a pixel electrode by forming a pixel gap with a dimension that is less than the limit of patterning by photolithography by self-alignment, and a method for manufacturing the same. About.

  Recently, there is an increasing demand for a projection display device for displaying a video on a large screen, such as a display for displaying a high-definition video such as a high-definition video. The projection type display device is roughly classified into a transmission type and a reflection type, and both types are applied with a spatial light modulation unit using an LCD (Liquid Crystal Display) panel as a liquid crystal display device. The readout light is incident on the panel, and the incident light is modulated in units of pixels in correspondence with the video signal so as to obtain projection light.

  Here, the LCD panel has a common transparent film formed on an active matrix substrate on which a switching element such as a thin film transistor and a pixel electrode whose potential is controlled by the switching element are arranged on a semiconductor substrate, and a transparent substrate (glass substrate or the like). An electrode and a liquid crystal sealed between the active matrix substrate and the common transparent electrode, and the potential difference between the common transparent electrode and each pixel electrode is changed for each pixel electrode corresponding to the video signal, The readout light is modulated by controlling the alignment of the liquid crystal (Patent Documents 1 and 2).

  Next, the configuration of the liquid crystal display device will be described taking a reflective liquid crystal display device as an example. FIG. 6 is a block diagram of a reflective liquid crystal display device. As shown in FIG. 6, in this liquid crystal display device, pixels Px are arranged in a matrix in the vertical direction and the horizontal direction, and each pixel Px has a signal wiring X extending from the horizontal shift register circuit 2 side for each column. Are connected to the gate wiring Y extending from the vertical shift register circuit 4 side for each row. Each signal wiring X is connected to a video line 8 that supplies a video signal via a video switch 6 (only one is shown in the figure), and an instruction from the horizontal shift register circuit 2 Is switched by.

Each pixel Px holds the potential of the pixel electrode 10, the reflective pixel electrode 10, the transparent electrode 12 common to each pixel Px across the liquid crystal, the switching element 14 that drives the pixel electrode 10, and the pixel electrode 10. Holding capacitor 16. Here, the respective pixel electrodes 10 are arranged in a matrix corresponding to the pixels Px with a pixel gap, which is a slight gap, between the adjacent pixel electrodes 10.
The switching element 14 has a gate G (see FIG. 7) connected to the gate wiring Y, a drain D connected to the signal wiring X, and a source S connected to the pixel electrode 10. In FIG. 6, a circuit configuration is shown in some pixels, and an arrangement position of circuit components is shown in other pixels.

  In this configuration, the video signal from the video line 8 is sequentially supplied by the video switch 6 with the timing shifted, and at the same time, the selection signal is sequentially supplied to the gate wiring Y by shifting the timing, whereby one specific pixel is Will be selected. Then, the input video signal is written in the storage capacitor 16 in the form of electric charges. A potential difference is generated between the pixel electrode 10 and the transparent electrode 12 in accordance with the video signal, and the optical characteristics of the liquid crystal sealed in the meantime are modulated. As a result, since the incident light L is modulated for each pixel Px, reflected by the pixel electrode 10 and output as readout light, unlike the conventional transmissive projector element, the incident light can be used nearly 100%, and has high definition and high brightness. And both.

  Here, the configuration of the pixel Px will be described in more detail. FIG. 7 is a cross-sectional view centered on one pixel of the conventional liquid crystal display device. As shown in the figure, this liquid crystal display device includes a semiconductor substrate 24 in which a plurality of reflective pixel electrodes 10 are formed on a surface in a matrix with a predetermined pixel gap 20 therebetween, and transparent electrodes 12 on all the pixels on the surface. It is mainly composed of a transparent substrate 26 formed in common across the pixel electrode 10 and a liquid crystal 28 sealed between the pixel electrode 10 and the transparent electrode 12. Here, a portion corresponding to one pixel electrode 10 corresponds to one pixel Px.

  The semiconductor substrate 24 is configured as follows as an active matrix substrate. That is, the semiconductor substrate 24 includes, for example, a silicon substrate 30, and a MOSFET switching element 14 including a source S, a gate G, and a drain D and a storage capacitor 16 are provided side by side on the silicon substrate 30. . The switching element 14 is provided on the well 32. The switching elements 14 and the storage capacitors 16 are separated from each other by a field oxide film 34. The source S of the switching element 14 and the storage capacitor 16 are connected.

  Then, a patterned first wiring layer 38 is formed through an initial interlayer insulating film 36 made of, for example, a SiO 2 film so as to cover the surfaces of the switching element 14 and the storage capacitor 16. A predetermined thickness, for example, made of Al, interposed between the first wiring layer 38 and the pixel electrode 10 so as to be sandwiched between the first interlayer insulating film 40 and the second interlayer insulating film 44. The first metal light shielding film 42 is patterned and formed. The first metal light-shielding film 42 is provided at least in a region corresponding to the lower part of the pixel gap 20 so as to block intrusion light from the pixel gap 20 on the way. That is, when intrusion light is incident on the drain D and the source S, which are the diffusion electrodes of the switching element 14, photocarriers are generated to cause a leakage current, which causes a fluctuation in the potential of the pixel electrode that is the origin of flicker and burn-in. By providing the first metal light-shielding film 42, a light path (optical path length) is increased to absorb light in the middle.

  The pixel electrode 10 is insulated from the first metal light shielding film 42, and the pixel electrode 10 is embedded in the embedded wirings 46 and 48 formed in the first and second interlayer insulating films 40 and 44. It is electrically connected to the source S via Here, the first and second interlayer insulating films 40 and 44 constitute an insulating layer. Further, antireflection films 50 and 52 made of, for example, TiN are formed on the upper surfaces of the first wiring layer 38 and the first metal light shielding film 42, respectively, and light entering through the pixel gap 20. Is to attenuate. The intrusion light is repeatedly reflected between the lower surface of the pixel electrode 10 and the first metal light-shielding film 42 and gradually attenuates, so that the light does not enter the switching element 14. A protective insulating film 54 is formed on the entire surface of the pixel electrode 10. An alignment film for aligning the liquid crystal 28 is formed on the surface of the protective insulating film 54 and the surface of the transparent electrode 12.

  The liquid crystal display device configured as described above is used as shown in FIG. FIG. 8 is a diagram showing a state including a peripheral portion of the liquid crystal display device, FIG. 8A shows a perspective view of the main body of the liquid crystal display device, and FIG. 8B shows a flexible printed wiring board on the main body. The top view of the connected state is shown. As shown in FIG. 8, the transparent substrate 26 is connected at a peripheral seal region 70 with a liquid crystal (not shown) sandwiched between a semiconductor substrate 24 made of a silicon substrate. Here, a portion where a large number of pixels Px are arranged is a pixel region 72. Further, a shift register circuit 74 including the horizontal shift register circuit 2 and the vertical shift register 4 is formed in the peripheral portion of the pixel region 72. The seal area 70 is provided outside the shift register circuit 74, and a seal material and spacer balls are applied thereto. The pixel region 72 has a spacerless structure in which a liquid crystal gap is created in the seal region 70 without using a spacer.

The transparent electrode formed on the transparent substrate 26 is coated with a conductive paste on the counter contact 76 formed on the semiconductor substrate 24, and is connected when the transparent substrate 26 and the semiconductor substrate 24 are bonded and fixed with a sealing material. The The counter contact 76 is wired to an external connection terminal 78, and a predetermined voltage can be applied from the external connection terminal 78.
As shown in FIG. 8B, a flexible printed wiring board 80 for supplying a signal from the outside is connected to the external connection terminal 78, and the external signal is provided on the flexible printed wiring board 80. It is input from the external input terminal 82. As described above, the liquid crystal display device and its peripheral part are configured.

JP-A-10-325949 JP 2001-318376 A

Incidentally, as shown in FIG. 7, when the intruding light L1 that has entered through the pixel gap 20 between the pixel electrodes 10 among the incident light L reaches the diffusion electrodes such as the source S and the drain D as described above, Since the source S and the drain D form a PN junction with the well 32 and form a photodiode, the intrusion light L1 is cut off and reduced in the middle in order to prevent generation of optical carriers. There is a need.
In addition, if the intrusion light L1 exists, the storage capacitor 16 is necessary to reduce the fluctuation of the potential of the pixel electrode 10 due to light leakage. If the light leakage is large, the storage capacitor 16 must be increased accordingly. This hinders pixel miniaturization.

By the way, the patterning of the transistors and wirings constituting the switching element 14 and the like is usually made by using photolithography, but the method for producing the pixel electrode 10 is not an exception, and the pixel electrode 10 is made by using photolithography. Are patterned in an array (matrix).
Furthermore, the pixel electrode 10 naturally has higher reflectivity and higher brightness and contrast when the area of reflection with respect to a limited pixel pitch is increased. This means that the smaller the pixel gap 20 is, the better. Further, if the pixel gap 20 is small, it becomes difficult for the projected image as a projector system to recognize the grid of the pixels Px, so that a smooth and seamless image can be displayed. For each of the above reasons, it is required to make the size (width) of the pixel gap 20 as small as possible.
The same applies to the transmissive liquid crystal display device. That is, in the transmissive liquid crystal display device, if the pixel gap between the pixel electrodes is small, the aperture ratio is improved, and the brightness and contrast are increased.

However, the above-described photolithography that performs reduction exposure with light has a limited patterning dimension. For example, even in an expensive Krf stepper that uses light with a wavelength of 248 nm, the normal minimum patterning has a limit of about 200 nm. .
In addition, when the Krf stepper is used for photolithography for forming a reflective pixel electrode, the minimum value of the dimension H1 (see FIG. 7) of the pixel gap 20 is limited to about 350 nm. This is because the pixel electrode is a reflective film, so the reflectance is high, and in photography that uses light for pattern formation, halation due to light, interference of light, etc. occur, so that fine photography is realized. This is because it is difficult.
In particular, in a reflective liquid crystal display device which is a large area chip, problems such as focus problems, mask dimensional variations, and exposure shot variations due to large area areas also occur. Was the limit.

  In order to solve the above problems, as disclosed in Patent Document 1, after forming a light shielding layer groove using an insulating film, a conductive film (aluminum) that serves as a pixel (reflection) electrode and light shielding layer. A method of forming a pixel electrode by self-alignment has been proposed. According to this method, since metal aluminum is formed below the pixel gap, the light-shielding layer can suppress the incidence of light, reduce light leakage, and reduce the pixel gap. In this case, the actual pixel gap is created by controlling the film thickness by sputtering. For this reason, since aluminum grows by sputtering and grains grow, if an attempt is made to reduce the pixel gap, a short circuit may occur between the pixel electrodes in the portion where the grains have grown. Therefore, the pixel gap cannot be formed in a size smaller than the grain grown by aluminum. In addition, since the grain size is not constant, it is difficult to control a fine pixel gap.

In Patent Document 1, sputtered aluminum is also formed as a light shielding layer in the light shielding layer groove. That is, when trying to increase the film thickness of the pixel electrode in order to reduce the pixel gap, the film thickness of the light shielding film formed in the light shielding layer groove is also increased at the same time. The groove should also be deep. Therefore, if the isotropic etching is performed by increasing the thickness of the silicon nitride film, which is an insulating film, to deepen the light shielding layer groove, the light shielding layer groove also increases and is disposed at the top of the light shielding layer groove. There is a problem that the gap between silicon dioxide, which is the same insulating film, is also increased.
Accordingly, the present invention has been made to solve the above-described problems, and a liquid crystal display device capable of forming a pixel gap having a size less than the limit of patterning by photolithography at low cost and a method for manufacturing the same. It is to provide.

According to a first aspect of the present invention, there is provided a substrate in which a plurality of pixel electrodes arranged in a matrix with a predetermined pixel gap are formed on a surface thereof via an insulating layer, and the pixel electrode has a predetermined gap. In a liquid crystal display device having a transparent substrate having an opposing transparent electrode formed on the surface thereof, and a liquid crystal filled in the gap,
A patterning film formed on each pixel electrode with a gap having a width larger than the dimension of the pixel interval between each other, and a periphery of each patterning film so as to surround each patterning film. A liquid crystal display device comprising: a sidewall formed at a corresponding position with a gap having substantially the same size as the pixel gap.

According to a second aspect of the present invention, there is provided a substrate having a plurality of pixel electrodes arranged in a matrix with a predetermined pixel gap and a switching element for supplying power to the pixel electrode formed on the surface thereof, the pixel electrode, In a method for manufacturing a liquid crystal display device, comprising: a transparent substrate having a transparent electrode formed on a surface thereof facing a predetermined gap; and a liquid crystal filled in the gap.
A conductive film forming step for forming a conductive film for forming the pixel electrode on one surface side of the substrate, and a first patterning film on the conductive film with a gap wider than the pixel gap therebetween. Forming a patterning film, forming an etching stopper film on the conductive film including the patterning film, forming a second patterning film on the etching stopper film, and A sidewall forming step of forming sidewalls spaced apart from each other with a gap of substantially the same size as the pixel gap at the periphery of the first patterning film by etching back the second patterning film; Using the sidewall as a mask, the etching stopper film exposed on the surface is removed to expose the conductive film And a pixel electrode forming step of forming the pixel electrode by pattern-etching the conductive film exposed on the surface using the first patterning film and the sidewall as a mask. This is a method for manufacturing a liquid crystal display device.

According to the liquid crystal display device and the method for manufacturing the same according to the present invention, the following excellent operational effects can be exhibited.
It is possible to form a pixel gap having a size less than the limit of patterning by photolithography at low cost. Therefore, since the effective pixel corresponding area of the pixel electrode is expanded, the brightness and contrast as a projector are improved.
Furthermore, in the case of a reflective liquid crystal display device, light entering from the pixel gap can be reduced, thereby reducing light leakage and reducing flicker and burn-in.

Hereinafter, an embodiment of a liquid crystal display device and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view centering on one pixel of an example of a liquid crystal display device according to the present invention, FIG. 2 is a partially enlarged view showing an enlarged portion of a pixel gap, which is part A in FIG. FIG. 4 is a process diagram showing the manufacturing process of the device of the present invention. In addition, the same code | symbol is attached | subjected about the component same as the component shown in FIGS.

First, the planar structure of the liquid crystal display device according to the present invention is the same as the structure shown in FIG. The cross-sectional structure is substantially the same as the structure shown in FIG. 7 except that a patterning film, an etching stopper film, and sidewalls are formed to reduce the pixel gap as will be described below.
That is, as shown in FIG. 1, this liquid crystal display device includes a semiconductor substrate 24 in which a plurality of reflective pixel electrodes 10 are formed on a surface in a matrix with a predetermined pixel gap 20 therebetween, and a transparent electrode 12 on the surface. Is mainly composed of a transparent substrate 26 formed in common over all pixels, and a liquid crystal 28 sealed between the pixel electrode 10 and the transparent electrode 12. Here, a portion corresponding to one pixel electrode 10 corresponds to one pixel Px.

  The semiconductor substrate 24 is configured as follows as an active matrix substrate. That is, the semiconductor substrate 24 includes, for example, a silicon substrate 30, and a MOSFET switching element 14 including a source S, a gate G, and a drain D and a storage capacitor 16 are provided side by side on the silicon substrate 30. . The switching element 14 is provided on the well 32. The switching elements 14 and the storage capacitors 16 are separated from each other by a field oxide film 34. The source S of the switching element 14 and the storage capacitor 16 are connected.

  Then, a patterned first wiring layer 38 is formed through an initial interlayer insulating film 36 made of, for example, a SiO 2 film so as to cover the surfaces of the switching element 14 and the storage capacitor 16. A predetermined thickness, for example, made of Al, interposed between the first wiring layer 38 and the pixel electrode 10 so as to be sandwiched between the first interlayer insulating film 40 and the second interlayer insulating film 44. The first metal light shielding film 42 is patterned and formed. The first metal light-shielding film 42 is provided at least in a region corresponding to the lower part of the pixel gap 20 so as to block intrusion light from the pixel gap 20 on the way. That is, when intrusion light is incident on the drain D and the source S, which are the diffusion electrodes of the switching element 14, photocarriers are generated, a leak current is generated, and the potential fluctuation of the pixel electrode that is the origin of flicker and burn-in is caused. By providing the first metal light-shielding film 42, a light path (optical path length) is increased to absorb light in the middle.

  The pixel electrode 10 is insulated from the first metal light shielding film 42, and the pixel electrode 10 is embedded in the embedded wirings 46 and 48 formed in the first and second interlayer insulating films 40 and 44. It is electrically connected to the source S via Here, the first and second interlayer insulating films 40 and 44 constitute an insulating layer. Further, antireflection films 50 and 52 made of, for example, TiN are formed on the upper surfaces of the first wiring layer 38 and the first metal light shielding film 42, respectively, and light entering through the pixel gap 20. Is to attenuate. The intrusion light is repeatedly reflected between the lower surface of the pixel electrode 10 and the first metal light-shielding film 42 and gradually attenuates, so that the light does not enter the switching element 14. A protective insulating film 54 is formed on the entire surface of the pixel electrode 10. An alignment film for aligning the liquid crystal 28 is formed on the surface of the protective insulating film 54 and the surface of the transparent electrode 12.

  Here, the size (width) H2 of the pixel gap 20 in the device of the present invention is formed to be considerably smaller than the size H1 of the pixel gap 20 of the conventional device shown in FIG. In order to realize a large dimension H2, a patterning film 90, an etching stopper film 92, and a sidewall 94 are provided as shown in the enlarged view of FIG. Specifically, the patterning film 90 is formed on each pixel electrode 10 with a gap having a dimension H3 wider than the dimension H2 of the pixel gap 20 from each other. For example, a SiO2 film is used as the patterning film 90 as a transparent insulating film. Then, a side wall 94 for self-alignment is formed in the periphery of each patterning film 90 so as to surround each patterning film 90, that is, via an etching stopper film 92.

  As the etching stopper film 92, for example, a transparent silicon nitride film which is an insulating film can be used. As the side wall 94, for example, a transparent SiO2 film which is an insulating film can be used. The dimension H4 of the gap between the side walls 94 is the same as the dimension H2 of the pixel gap 20 of the pixel electrode 10. In other words, the pixel electrode 10 is formed by self-alignment by pattern etching using the sidewall 94 as a mask, as will be described later, so that both the dimensions H2 and H4 have the same value. Here, both the dimensions H2 and H4 can be set to about 100 nm, and can be made much smaller than the dimension H1 of the conventional apparatus of about 350 nm.

Since the operation of the reflective liquid crystal display device is the same as that of the conventional reflective liquid crystal display device described above, the description thereof is omitted.
The reflective liquid crystal display device of the present invention described above can increase the area of the pixel electrode 10 as compared with the conventional device, so that the reflectance is improved and the brightness and contrast as a projector can be improved. Light entering from 20 (intrusion light) can be reduced. As a result, light leakage can be reduced and flicker and image sticking can be reduced.

In this case, light leakage can be remarkably suppressed as compared with the conventional structure even when the pixel size is reduced, so that a high-resolution panel by reducing the pixel size and cost reduction can be realized.
In addition, the improvement in contrast of the device of the present invention improves the black reproducibility, for example, and improves the gradation of the dark part, so that the black floating that is a drawback of the projection projector can be remarkably improved. Visibility can be improved.

Next, the manufacturing method of the above-described device of the present invention will be specifically described.
First, up to the second interlayer insulating film 44 immediately below the pixel electrode 10 shown in FIGS. 1 and 2 is formed by repeatedly performing the same normal method as the conventional method, that is, film formation and etching.
Then, as shown in FIG. 3A, a reflective conductive film 100 to be the pixel electrode 10 later is formed on the entire surface of the second interlayer insulating film 44 as in the conventional method (reflective conductive film forming step). ). As the reflective conductive film 100, for example, an aluminum film having a high reflectance can be used.

  Next, as shown in FIG. 3B, an insulating film having a thickness of about 300 nm is formed on the reflective conductive film 100 over the entire surface by CVD, and this insulating film is patterned into a pixel electrode shape by photolithography. Further, this insulating film is processed into a pixel electrode shape by etching to form a patterning film 90 as a first patterning film (patterning film forming step). The dimension H3 of the gap 102 of the patterning film 90 created at this time is set wider than a preset dimension H1 of the pixel gap 20 to be formed in a later process, for example, 100 nm, using photolithography. It is formed to about 600 nm.

At this time, since the dimension H3 of the gap 102 formed by the patterning film 90 may be about 600 nm, it is not necessary to use an expensive Krf stepper or an expensive high-sensitivity resist. A sufficient i-line stepper can be used. As the patterning film 90, for example, a transparent SiO2 film can be used.
Next, as shown in FIG. 3C, an etching stopper film 92 made of an insulating film is formed on the entire surface including the patterning film 90 by CVD (etching stopper film forming step).
As the etching stopper film 92, a transparent nitride film, for example, a silicon nitride film (SiN) can be used. As a result, an etching stopper film 92 is formed over the entire surface of the patterning film 90 and the inner surface of the gap 102.

  Next, as shown in FIG. 3D, a sidewall insulating film 104 as a second patterning film is formed on the etching stopper film 92 with a predetermined thickness over the entire surface by CVD. As this insulating film 104, for example, a transparent SiO2 film can be used. The insulating film 104 has a thickness of, for example, about 200 nm, and is formed with a controlled thickness so that at least a slight gap 106 remains so that the gap 102 is not completely buried.

  Next, as shown in FIG. 3E, the insulating film 104 is etched back by using an oxide film etching apparatus, so that a sidewall 94 is formed around the patterning film 90 so as to surround it. Form. At this time, CHF3 and CF4 gases are introduced in a vacuum atmosphere, RF plasma is generated, and anisotropic etching is performed. A sidewall 94 made of the insulating film 104 is formed on the sidewall of the patterning film 90 with the etching stopper film 92 interposed therebetween (sidewall formation step). The end point by etch back is detected at the point where the etching stopper film 92 is exposed. Therefore, the dimension H4 of the gap between the sidewalls 94 can be accurately controlled by the film thickness of the insulating film 104. In other words, the film thickness of the insulating film 104 is set so as to obtain a desired dimension H4. This dimension H4 is much smaller than the dimension H3 of the gap 102, and this dimension H4 becomes the dimension H2 of the pixel gap.

Next, by changing the gas ratio in a chamber different from the oxide film etching apparatus, the etching stopper film 92 exposed on the surface with the sidewall 94 as a mask is formed as shown in FIG. Etching removes the underlying patterning film 90 and exposes the reflective conductive film 100 in the gap 106 of the sidewall 94. At this time, the etching stopper film 92 slightly remains on the bottom surface of the sidewall 94 and the side surface on the patterning film 90 side. However, since the etching stopper film 92 is the same insulating film as the sidewall 94 and the patterning film 90, no problem occurs even if it remains.
Next, as shown in FIG. 4B, the reflective conductive film 100 is etched by an aluminum etching apparatus using the patterning film 90 and the side wall 94 as a hard mask, and is exposed between the side walls 94. The reflective conductive film 100 is removed, and the pixel electrode 10 having the gap 20 with the dimension H2 is formed (pixel electrode forming step). In the case of the present embodiment, the dimension of the gap 20 of the completed pixel electrode 10 is set to 100 nm.

  Thereafter, since the patterning film 90, the remaining etching stopper film 92, and the sidewalls 94 are all transparent films, there is no effect of preventing the action of reflecting light incident from the upper part of the reflective liquid crystal display device. Therefore, the protective insulating film 54 may be formed on the upper surface as shown in FIG.

Alternatively, since the patterning film 90, the remaining etching stopper film 92, and the side wall 94 have finished the role of creating a small pixel gap 20, they are removed and protected as shown in FIG. An insulating film 54 may be formed.
When all of the patterning film 90, the etching stopper film 92, and the sidewall 94 are finally removed, these may be formed of an opaque member instead of a transparent member.

The surface of the protective insulating film 54 formed as described above is flattened by CMP (Chemical Mechanical Polishing), and an alignment film (not shown) is formed thereon to substantially complete the semiconductor substrate 24 side. Thereafter, as shown in FIG. 1, the semiconductor substrate 24 and the transparent substrate 26 having the transparent electrode 12 are opposed to each other, and a liquid crystal 28 is sealed between the two substrates to complete the liquid crystal display device. Become.
As shown in the above production method, the dimension H2 of the gap 20 of the pixel electrode 10 can be controlled regardless of the resolution of photolithography. Therefore, using an inexpensive stepper capable of fine exposure, a resist capable of high resolution, other EB (electron beam) exposure apparatus, nanoimprint apparatus, etc. Thus, the pixel electrode 10 having a fine pixel gap 20 can be formed.

  In addition, as described above, in the case of the pixel electrode 10 of the reflective liquid crystal display device, the pixel electrode 10 is a reflective film and thus has a high reflectance. In photography using light for pattern formation, halation or light caused by light is used. In particular, in a reflective liquid crystal display device which is a large area chip, there is a problem of focus, mask size variation, Since problems such as exposure shot variation due to a large area also occur, photolithography using a stepper has become a problem of accuracy due to the apparatus. However, if the method of the present invention is used, it is difficult with inexpensive equipment. A pixel electrode 10 having a fine pixel gap 20 can be formed even in a reflective film having a high reflectance without requiring process control. .

Further, the side wall 94 formed on the side wall of the patterning film 90 is excellent in the uniformity of the film thickness within the surface of the wafer, as is well known because the film is formed by CVD. Therefore, the dimension H4 (H2) of the gap 20 of the side wall 94 formed on the side wall of the patterning film 90 can be controlled relatively uniformly. Accordingly, the dimension H2 of the pixel gap 20 has little variation and can be formed uniformly.

Further, since the pixel gap 20 can be made small by the method of the present invention, light incident from the pixel gap 20 can be greatly reduced.

Therefore, almost no light is applied to the diffusion electrode of the switching element that drives the pixel, and the leakage current due to the optical carrier can be greatly reduced.
This makes it possible to reduce the storage capacity necessary for reducing the fluctuation of the potential of the pixel electrode 10 due to light leakage, and to achieve significant pixel miniaturization.
Furthermore, since the dimension of the pixel gap 20 is not restricted by photolithography as described above, when it is desired to change the dimension H2 of the pixel gap 20, without creating an expensive photolithography mask, The dimension H2 of the pixel gap 20 can be easily changed.

Specifically, it is only necessary to change the thickness of the insulating film 104 used for the sidewall 94, and the dimension H2 of the pixel gap 20 can be easily changed only by changing the film formation time of the oxide film CVD apparatus.
This has an advantage that, for example, a reflective liquid crystal display device corresponding to the three primary colors of RGB can easily optimize the gap between the pixel electrodes.
For example, light incident on a reflective liquid crystal display device for B light is 400 to 500 nm color light, light incident on a reflective liquid crystal display device for G light is 500 nm to 600 nm color light, and reflective light for R light. The light incident on the liquid crystal display device is limited to 600 nm to 780 nm color light.

  Here, looking at the reflection type liquid crystal display device for R light, if the gap between the pixel electrodes forming the pixel is set to 600 nm or less, light other than the gap and the horizontal direction in the pixel gap is The light is reflected or absorbed by the pixel electrode and is not incident on the switching element. A plan view of the pixel electrode viewed from above is shown in FIG.

For this reason, most of light incident on the pixel transistor from the pixel electrode can be cut, and leakage current due to light can be prevented.
The same applies to the reflective liquid crystal display device for G light. If the gap between the pixel electrodes forming the pixels is set to 500 nm or less, the light other than the gap and the horizontal direction in the pixel gaps The light is reflected or absorbed by the light and is not incident on the switching element. A plan view of the pixel electrode viewed from above is shown in FIG.

For this reason, most of light incident on the pixel transistor from the pixel electrode can be cut, and leakage current due to light can be prevented.
The same applies to the reflective liquid crystal display device for B light. If the gap between the pixel electrodes forming the pixel is set to 400 nm or less, the light other than the gap and the horizontal direction in the pixel gap The light is reflected or absorbed by the electrode and is not incident on the switching element. A plan view of the pixel electrode viewed from above is shown in FIG.
For this reason, most of light incident on the switching element from the pixel electrode can be cut, and leakage current due to light can be prevented.

Here, according to the present invention, it is possible to easily create a pixel electrode having a pixel gap corresponding to each of the RGB reflective liquid crystal display devices.
That is, up to the formation of the patterning film 90 and the etching stopper film 94, each color light reflective liquid crystal display device can be manufactured by the same process.
After that, when forming the side wall 94 as the final process, for the reflective liquid crystal display device corresponding to each color light of R, G, B, the distance for the gap H2 of the pixel electrode is made to correspond to the distance for the side wall 94. Since the insulating film 104 may be formed by changing the film thickness, the device can have a certain degree of versatility as compared with Patent Document 2.

That is, the reflective liquid crystal display device corresponding to each color light of R, G, B is made in the same process until the process before the formation of the insulating film 104, and corresponds to each color light of R, G, B as required. A reflective liquid crystal display device in which the thickness of the insulating film 104 is set can be created and divided.
Furthermore, according to the present invention, since the pixel gap to be finally formed is created by aluminum etching, it is not limited by aluminum grains as in Patent Document 1.
Since the pixel gap is reliably formed by etching, it is possible to create an accurate pixel gap.
Further, unlike Patent Document 1, it is not necessary to form a light-shielding film of conductive aluminum below the pixel gap, so that a problem of short-circuiting between pixel electrodes via the light-shielding film does not occur.

  Hereinafter, another embodiment of the liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings. The present invention can also be applied to a transmissive liquid crystal display device. As shown in FIGS. 9 and 10, the gate wiring 150 and the video line 120 are formed on the insulating substrate 130 made of a transparent member such as glass on which the base protective film 131 is formed, and from the ITO film through the source electrode 180. The pixel electrodes 110 are electrically connected and driven using thin film transistors (TFTs).

  FIG. 10 is a partially enlarged view of the cross section of the adjacent pixel electrode 110, which is a portion B in FIG. 9. As shown in the figure, a base protective film 131, a video line 120, a patterning film 190, a pixel electrode 110, a protective insulating film 154, a liquid crystal 128, a transparent electrode 112, and a transparent substrate 126 are stacked on an insulating substrate 130. .

  Here, the size of the pixel gap 121 is formed to be considerably smaller than the size of the pixel gap of the conventional device by using the above-described manufacturing process. In order to realize this fine size, an enlarged view shown in FIG. As shown, the patterning film 190, the etching stopper film 192, and the sidewall 194 are provided. Specifically, the patterning film 190 is formed on each pixel electrode 110 with a gap having a width larger than that of the pixel gap being separated from each other. For example, a SiO2 film is used for the patterning film 190 as a transparent insulating film. Then, a side wall 194 for self-alignment is formed on the periphery of each patterning film 190 so as to surround each patterning film 190, that is, via an etching stopper film 192.

  As the etching stopper film 192, an insulating film such as a transparent silicon nitride film can be used. The sidewall 194 can be an insulating film such as a transparent SiO2 film. The size of the gap between the sidewalls 194 is the same as the size of the pixel gap 121 of the pixel electrode 110. In other words, since the pixel electrode 110 is formed by self-alignment by pattern etching using the sidewall 194 as a mask, both dimensions have the same value. Here, both the above dimensions can be set to about 100 nm, and can be significantly smaller than the dimensions of the conventional apparatus.

In the case of a transmissive liquid crystal display device, as shown in FIG. 9, the TFT driving lines and electrodes block the light transmitted through the liquid crystal display device, but the effective pixel corresponding area of the pixel electrode is enlarged. As in the case of the liquid crystal display device, brightness and contrast as a projector are improved.
Further, although metal materials are used for the wiring and electrodes for driving the TFT, when a transparent member is applied to these members, the effect of improving the brightness and contrast as a projector can be expected.

It is sectional drawing shown centering on one pixel of an example of the liquid crystal display device which concerns on this invention. FIG. 2 is a partial enlarged view showing an enlarged pixel gap portion which is an A portion in FIG. 1. It is process drawing which shows the manufacture process of this invention apparatus. It is process drawing which shows the manufacture process of this invention apparatus. It is a top view which shows the state which looked at the pixel electrode made into various dimensions of a pixel gap from the upper part. It is a block block diagram which shows a reflection type liquid crystal display device. It is sectional drawing represented centering on one pixel of the conventional liquid crystal display device. It is a figure which shows the state also including the peripheral part of a liquid crystal display device. FIG. 6 is a partial view showing a transmissive liquid crystal display device which is another embodiment of the liquid crystal display device according to the present invention. FIG. 10 is a partial enlarged cross-sectional view showing an enlarged portion of a pixel gap that is a B portion in FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,110 ... Pixel electrode 12, 112 ... Transparent electrode 14 ... Switching element 20, 121 ... Pixel gap 24 ... Semiconductor substrate 26, 126 ... Transparent substrate 28, 128 ... Liquid crystal 54, 154 ... Protective insulating film 90, 190 ... Patterning film 92, 192 ... Etching stopper films 94, 194 ... Sidewall 100 ... Reflective conductive film 102 ... Gap 120 between patterning films ... Video line 130 ... Insulating substrate 150 ... Gate wiring 180 ... Source electrode H2 ... Pixel gap dimension H3 ... Patterning Dimension of gap between membranes

Claims (2)

A substrate in which a plurality of pixel electrodes arranged in a matrix with a predetermined pixel gap are formed on the surface via an insulating layer, and a transparent electrode facing the pixel electrode with a predetermined gap on the surface In a liquid crystal display device having a transparent substrate formed on and a liquid crystal filled in the gap,
A patterning film formed on each of the pixel electrodes with a gap having a width wider than the pixel spacing;
A sidewall formed at a position corresponding to the pixel gap at a periphery of each patterning film so as to surround the periphery of each patterning film, with a gap having substantially the same size as the pixel gap;
A liquid crystal display device comprising: A plurality of pixel electrodes arranged in a matrix with a predetermined pixel gap and a switching element that supplies power to the pixel electrode are formed on the surface of the substrate, and the pixel electrode is opposed to the pixel electrode with a predetermined gap. In a method of manufacturing a liquid crystal display device having a transparent substrate on which a transparent electrode is formed and a liquid crystal filled in the gap,
A conductive film forming step of forming a conductive film for forming the pixel electrode on one side of the substrate;
A patterning film forming step of forming a first patterning film on the conductive film by separating a gap having a width larger than that of the pixel gap from each other;
An etching stopper film forming step of forming an etching stopper film on the conductive film including the patterning film;
Forming a second patterning film on the etching stopper film;
A sidewall forming step of forming sidewalls separated from each other with a gap of approximately the same size as the pixel gap around the first patterning film by etching back the second patterning film; ,
Removing the etching stopper film exposed on the surface using the sidewall as a mask to expose the conductive film;
A pixel electrode forming step of forming the pixel electrode by pattern-etching the conductive film exposed on the surface using the first patterning film and the sidewall as a mask;
A method for manufacturing a liquid crystal display device, comprising:

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