JP2006072106A - Reflective liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve contrast and luminance in relation to a structure of a reflective liquid crystal display device. <P>SOLUTION: The reflective liquid crystal display device comprises: a plurality of switching elements 14 formed for each pixel on a semiconductor substrate 11; a plurality of pixel electrodes 30W formed on the uppermost layer out of a multilayer film laminated on the upper side of the plurality of switching elements, while being connected to the respective switching elements, separated for the respective pixels with gaps of electrodes on the rectangular circumference, further in a thin film by using a metal film material to transmit a part of incident light LIW and to reflect residual incident light; a metal light shielding film 28 formed in the multilayer film on the lower side of the plurality of pixel electrodes and via an interlayer insulating layer 29W and further shielding a part of incident light passed through the plurality of pixel electrodes toward the lower side and reflecting it to the plurality of pixel electrodes side; a transparent counter electrode 44 formed on a transparent substrate 45; and a liquid crystal sealed so that the plurality of pixel electrodes and the transparent counter electrode are placed opposite to each other, across alignment layers 41, 43 placed opposite to each other between both electrodes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of a reflective liquid crystal display device, and in particular, a reflection that can improve contrast and brightness by forming a two-layered reflective film (pixel electrode and metal light-shielding film) for incident light. The present invention relates to a liquid crystal display device.

  Recently, a projection type for displaying images on a large screen, such as a display for outdoor public use or control operations, or a display for displaying high-definition images typified by the high definition broadcasting standard or the SVGA standard for computer graphics. Liquid crystal display devices are actively used.

  This type of projection type liquid crystal display device can be broadly divided into a transmission type liquid crystal display device using a transmission method and a reflection type liquid crystal display device using a reflection method. In the case of the former transmission type liquid crystal display device, However, since the area of a TFT (Thin Film Transistor) provided in each pixel does not become a transmission area of a pixel that transmits light, the aperture ratio becomes small. A liquid crystal display device has attracted attention.

  Generally, in the above-described reflective liquid crystal display device, a plurality of switching elements are electrically separated from each other on a semiconductor substrate (Si substrate), and the multilayer film is stacked above the plurality of switching elements. In the uppermost layer, a plurality of reflective pixel electrodes corresponding to a plurality of switching elements are electrically separated from each other, and one reflective pixel electrode connected to one switching element and a storage capacitor portion for the switching element are assembled. A plurality of pixels are arranged in a matrix on a semiconductor substrate, and a transparent counter electrode that is common to all the pixels and is opposed to the plurality of reflective pixel electrodes is formed on a transparent substrate (glass substrate). By forming a film on the bottom surface and enclosing the liquid crystal between a plurality of reflective pixel electrodes and the counter electrode, incident light enters the liquid crystal through the counter electrode from the transparent substrate side. By, after the light modulated by the liquid crystal in accordance with the incident light to a signal from the switching element, it is intended to emit the read light is reflected by the plurality of reflective pixel electrodes from the transparent substrate side.

As a conventional example of this type of reflective liquid crystal display device, the present applicant has previously proposed a device that can suppress leak light reaching the switching element (see, for example, Patent Document 1).
FIG. 11 is a cross-sectional view schematically showing one pixel in a conventional reflective liquid crystal display device.

  The reflective liquid crystal display device 10 of the conventional example shown in FIG. 11 is configured by applying the technical idea of the above-described Patent Document 1 (Japanese Patent Laid-Open No. 2001-318376), and is not shown. The present invention is configured to be applicable to a reflective liquid crystal projector.

In the reflective liquid crystal display device 10 of the conventional example described above, one pixel among a plurality of pixels for displaying an image will be described in an enlarged manner. A semiconductor substrate 11 serving as a base is made of single crystal silicon or the like. A p-type Si substrate (or an n-type Si substrate may be used), and one p ⁻ well region 12 is provided on the left side of the semiconductor substrate (hereinafter referred to as a p-type Si substrate) 11 in the left and right field oxidation. The films 13A and 13B are provided in a state of being electrically separated in units of pixels. One switching element 14 is provided in one p ^- well region 12, and this switching element 14 is configured as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

Further, one switching element (hereinafter referred to as MOSFET) 14 has a gate G 16 formed by forming a gate electrode 16 made of polysilicon on a gate oxide film 15 located substantially at the center on the p ⁻ well region 12. Is formed.

  Further, a drain region 17 is formed on the left side of the gate G of the MOSFET 14 in the figure, and a drain electrode 18 is formed on the drain region 17 by an aluminum wiring in the first via hole Via1, thereby forming a drain D. Has been.

  Further, a source region 19 is formed on the right side of the gate G of the MOSFET 14 in the figure, and a source electrode 20 is formed on the source region 19 by aluminum wiring in the first via hole Via1, thereby forming a source S. Has been.

Further, an ion-implanted diffusion capacitor electrode 21 is formed on the p-type Si substrate 11 on the right side of the p ^- well region 12 in the drawing, and this diffusion capacitor electrode 21 is also formed in pixel units by left and right filled oxide films 13B and 13C. The range from the filled oxide film 13A to the filled oxide film 13C corresponds to one pixel.

  Further, the insulating film 22 and the capacitor electrode 23 are sequentially formed on the diffusion capacitor electrode 21, and the capacitor electrode contact 24 is formed on the capacitor electrode 23 by the aluminum wiring in the first via hole Via 1. Thus, a storage capacitor portion C corresponding to one MOSFET 14 is formed.

  Above the field oxide films 13A to 13C, the gate electrode 16 and the capacitor electrode 23, a first interlayer insulating film 25, a first metal film 26, a second interlayer insulating film 27, and a second metal film 28 are provided. The multilayer films 25 to 30 each including the third interlayer insulating film 29 and the third metal film 30 are stacked in the order described above.

At this time, the first, second, and third interlayer insulating films 25, 27, and 29 are formed using insulating and transparent SiO ₂ (silicon oxide) or the like.

  The first, second, and third metal films 26, 28, and 30 are partitioned into a predetermined pattern shape for each pixel corresponding to one MOSFET 14 by conductive aluminum (Al) wiring or the like. In the same pixel, the first, second and third metal films 26, 28 and 30 are electrically connected to each other, but the first and second metal films 26 and 28 are adjacent to adjacent pixels. The openings 26a and 28a are respectively formed between the adjacent films, and the electrode gap 30a is formed between the adjacent films of the third metal film 30 serving as a reflective pixel electrode, as will be described later. One first, second, and third metal films 26, 28, and 30 are electrically separated for each pixel.

  The lower first metal film 26 in one pixel is formed by forming an aluminum wiring in each first via hole Via1 obtained by etching the first interlayer insulating film 25, the source electrode 20, The capacitor 14 is connected to one MOSFET 14 and the storage capacitor C via a capacitor electrode contact 24.

  Further, in one pixel, the second metal film 28 in the middle layer is provided as a metal light shielding film for shielding a part of incident light LI incident from the transparent substrate 45 side described later to the lower layer side. It is what. That is, the second metal film (metal light shielding film) 28 forms the electrode gap 30a so as to shield part of the incident light LI entering from the electrode gap 30a formed between the adjacent third metal films 30 in the uppermost layer. The film is formed so as to cover it, and is connected to the lower first metal film 26 by forming an aluminum wiring in the second via hole Via2 obtained by etching the second interlayer insulating film 27.

  Further, in one pixel, the uppermost third metal film 30 is divided into a square shape by an electrode gap 30a formed between adjacent third metal films 30 corresponding to one pixel, and thus one reflective pixel. It is provided as an electrode and is connected to the second metal film 28 in the middle layer by forming an aluminum wiring in the third via hole Via3 obtained by etching the third interlayer insulating film 29.

  Further, antireflection films 31 and 32 are formed on the first and second metal films 26 and 28 using TiN (titanium nitride: titanium nitride), respectively. These antireflection films 31 and 32 allow the incident light LI that has entered from the electrode gap 30 a formed between the third metal films 30 to pass between the third metal film 30 and the second metal film 28 and the second metal film 28. Reflection on the second and first metal films 28 and 26 is prevented by attenuating between the metal film 28 and the first metal film 26, respectively.

  Further, a liquid crystal 42 is sealed above a third metal film (hereinafter also referred to as a reflective pixel electrode) 30 with an alignment film 41, 43 facing each other, and a transparent counter electrode 44 is interposed via the liquid crystal 42. Is opposed to the plurality of reflective pixel electrodes 30 on the lower surface of a transparent substrate (glass substrate) 45 having optical transparency, and is not partitioned for each pixel as a common electrode for each reflective pixel electrode 30 (Indium Tin Oxide) The film is formed using, for example.

  Then, incident light LI is incident from the transparent substrate 45 side, and the incident light LI is transmitted through the counter electrode 44, the alignment film 43, the liquid crystal 42, and the alignment film 41 in order, and then reflected by the reflective pixel electrode 30. Light-modulated readout light L for image is emitted from the transparent substrate 45 side through the alignment film 41, the liquid crystal 42, the alignment film 43, and the counter electrode 44. Thereafter, the readout light L for image emitted from the transparent substrate 45 is enlarged and projected onto a screen (not shown) by a projection lens in a reflective liquid crystal projector (not shown).

  Incidentally, in the conventional reflective liquid crystal display device 10 shown in FIG. 11, as described above, a part of the incident light LI incident from the transparent substrate 45 side is the third metal film (reflective pixel) adjacent to the uppermost layer. Electrode) enters into the second metal film 28 in the middle layer from the electrode gap 30a formed between the electrodes 30, and repeats reflection between the second and third metal films 28 and 30 and further adjoins the middle layer. When an attempt is made to enter the lower first metal film 26 from the gap 28 a formed between the second metal films 28, the antireflection films 31 and 32 form TiN on the first and second metal films 26 and 28. As shown in FIG. 12, the light leakage does not occur because a part of the incident light LI is prevented from being reflected and a part of the incident light LI cannot reach the MOSFET 14 side. New It is occurring problems.

  FIG. 12 is a schematic enlarged view showing a film formation distribution state of an alignment film in an electrode gap formed between adjacent reflective pixel electrodes in a conventional reflective liquid crystal display device.

  As shown in FIG. 12, in the conventional reflective liquid crystal display device 10 (FIG. 11), aluminum (Al) is normally used as the metal film material of the reflective pixel electrode (third metal film) 30. This aluminum has both functions of reflecting incident light LI incident from the transparent substrate 45 side and applying a voltage to the liquid crystal 42. For this reason, since it is important for the reflective pixel electrode 30 to reflect the incident light LI and emit the readout light L, it is necessary to set the film thickness so that the incident light LI is not transmitted. The film thickness of 30 is limited to about 250 nm, and when the film thickness is set to 250 nm or less, the incident light LI is transmitted, so that the reflectance is lowered and the light use efficiency is lowered.

  Therefore, when the plurality of reflective pixel electrodes 30 are formed with a thickness of 250 nm or more using aluminum, and the alignment film 41 is formed in contact with the upper surface of the plurality of reflective pixel electrodes 30, adjacent reflective pixels are formed. Since the height of the electrode gap 30a formed between the electrodes 30 corresponds to a step of 250 nm or more depending on the film thickness of the reflective pixel electrode 30, the alignment film 41 formed by intruding into the electrode gap 30a is reflected by this reflection. The alignment film 41 cannot be uniformly formed in a shadow portion due to the step (250 nm or more) of the pixel electrode 30. As a result, the orientation of the liquid crystal 42 is disturbed at the end of the reflective pixel electrode 30, so that the function of transmitting (ON) or blocking (OFF) the incident light LI and the readout light L does not work well. There is a new problem that the contrast to L is lowered.

  Therefore, there is a demand for a reflective liquid crystal display device that can uniformly form an alignment film in contact with a plurality of pixel electrodes, improves the contrast to readout light, and can improve the reflectance with respect to incident light. .

The present invention has been made in view of the above problems, and the invention according to claim 1 includes a plurality of switching elements formed for each pixel on a semiconductor substrate,
Among the multilayer films stacked above the plurality of switching elements, the uppermost layer is connected to each switching element, and the periphery of the rectangle is separated for each pixel by an electrode gap, and a part of incident light is transmitted. And a plurality of pixel electrodes formed in a thin film using a metal film material to reflect the remaining incident light,
In the multilayer film, the plurality of pixel electrodes are formed below the plurality of pixel electrodes with an interlayer insulating film interposed therebetween, and the plurality of incident lights transmitted through the plurality of pixel electrodes are shielded against a lower layer side. A metal light-shielding film that reflects to the pixel electrode side;
A transparent counter electrode formed on a transparent substrate;
The plurality of pixel electrodes and the transparent counter electrode are opposed to each other, and the liquid crystal is sealed with an alignment film facing each other between the electrodes.
The incident light incident from the transparent substrate side is optically modulated by the liquid crystal in accordance with a signal from each switching element, and then reflected by the plurality of pixel electrodes and the metal light-shielding film. The reflection type liquid crystal display device is configured to emit readout light from the liquid crystal display device.

According to a second aspect of the present invention, in the reflective liquid crystal display device according to the first aspect,
The plurality of pixel electrodes is a reflective liquid crystal display device having a film thickness of 10 nm or less using TiN or Ti as the metal film material.

Furthermore, the invention according to claim 3 is the reflective liquid crystal display device according to claim 1 or 2,
The reflective liquid crystal display device is characterized in that a thickness of the interlayer insulating film formed between the plurality of pixel electrodes and the metal light shielding film is set in accordance with a center wavelength of the incident light.

  According to the reflective liquid crystal display device of the present invention, a plurality of pixel electrodes are formed into a thin film using a metal film material such as TiN or Ti, and an alignment film is formed in contact with the upper surfaces of the plurality of pixel electrodes. In this case, the height of the electrode gap formed between adjacent pixel electrodes corresponds to a step due to the film thickness of the pixel electrode. The alignment film can be formed uniformly without being affected by the above. As a result, the orientation of the liquid crystal is not disturbed at the end of the pixel electrode, and the function of transmitting (on) or blocking (off) incident light and readout light works well. improves.

  In addition, when a plurality of pixel electrodes are formed into a thin film using a metal film material such as TiN or Ti, even if some of the incident light incident from the transparent substrate is transmitted through the plurality of pixel electrodes, Since the light is reflected by the plurality of pixel electrodes and the metal light shielding film, a sufficient reflectance can be secured.

  Furthermore, the thickness of the interlayer insulating film formed between the metal light-shielding film and the plurality of pixel electrodes is set so that the light interference effect is maximized according to the center wavelength of the incident light. Since the reflectance from the metal light shielding film increases, the luminance can be improved.

  An embodiment of a reflective liquid crystal display device according to the present invention will be described in detail below in the order of Embodiment 1 and Embodiment 2 with reference to FIGS.

  In the reflection type liquid crystal display devices of Examples 1 and 2, the same components as those in the reflection type liquid crystal display device of the conventional example described above with reference to FIG. The constituent members will be described as necessary, and the constituent members different from the conventional example will be described with new reference numerals.

FIG. 1 is a cross-sectional view schematically showing one pixel in a reflective liquid crystal display device according to a first embodiment of the present invention.
FIG. 2 shows a reflection type liquid crystal display device according to the first embodiment of the present invention, in which the thickness of the pixel electrode formed using TiN is varied, and TiN / SiO ₂ / Al of the incident light having a center wavelength of 550 nm is changed. A diagram showing the reflectivity,
FIG. 3 shows a reflection type liquid crystal display device according to the first embodiment of the present invention. When the film thickness of the pixel electrode formed using Ti is varied, Ti / SiO ₂ / Al of the incident light having a center wavelength of 550 nm is shown. A diagram showing the reflectivity,
FIG. 4 shows a TiN / SiO ₂ film for incident light having a center wavelength of 550 nm when the thickness of the third interlayer insulating film formed using SiO ₂ is varied in the reflective liquid crystal display device of Example 1 according to the present invention. ₂ shows the reflectivity of Al.
FIG. 5 is a diagram schematically showing an enlarged distribution state of an alignment film in an electrode gap formed between adjacent pixel electrodes in the reflective liquid crystal display device of Example 1 according to the present invention.
FIG. 6A is a block diagram for explaining an active matrix circuit in the reflection type liquid crystal display device of Example 1 according to the present invention, and FIG. 6B is an enlarged view of an X portion in FIG. It is a schematic diagram.

  The reflective liquid crystal display device 10W according to the first embodiment of the present invention shown in FIG. 1 makes white incident light LIW including red light, green light, and blue light incident from the transparent substrate 45 side, and this white After the incident light LIW is optically modulated for each pixel by the liquid crystal 42, it is reflected by a pixel electrode 30W and a second metal film (metal light shielding film) 28, which will be described later, and the white readout light LW is emitted from the transparent substrate 45 side. It is configured as follows. The reflective liquid crystal display device 10W is applied to a single-plate reflective liquid crystal projector (not shown). The reflective liquid crystal display device 10W can also be applied to a three-plate reflective liquid crystal projector described later.

As shown in FIG. 1, in the reflective liquid crystal display device 10W according to the first embodiment of the present invention, one pixel among a plurality of pixels for displaying an image will be described in detail. Similar to the reflection type liquid crystal display device 10 of the prior art 1 described above, one p ^- well region 12 is electrically connected to the p-type Si substrate (semiconductor substrate) 11 by the left and right filled oxide films 13A and 13B in units of pixels. Are separated from each other. One MOSFET (switching element) 14 is provided in one p ⁻ well region 12. This MOSFET 14 includes a gate G having a gate electrode 16 formed on a gate oxide film 15, a drain D having a drain electrode 18 formed on a drain region 17, and a source having a source electrode 20 formed on a source region 19. S.

Further, on the p-type Si substrate 11, on the right side of the p ^- well region 12, a storage capacitor portion C 1 including a diffusion capacitor electrode 21, an insulating film 22, a capacitor electrode 23, and a capacitor electrode contact 24 is formed. The capacitor portion C1 is electrically separated in pixel units by the left and right filled oxide films 13B and 13C.

  Of the multilayer films stacked above the filled oxide films 13A to 13C, the gate electrode 16, and the capacitor electrode 23, the first interlayer insulating film 25 to the first metal film 26, the second interlayer insulating film 27, and the second metal film are provided. The layers up to (metal light shielding film) 28 are formed in the same manner as in the conventional example (FIG. 11).

  At this time, the lower first metal film 26 formed using aluminum (Al) is connected to one MOSFET 14 via the drain electrode 18, the source electrode 20, and the capacitor electrode contact 24 by the aluminum wiring in the first via hole Via 1. Each is connected to the storage capacitor C1.

  Further, the middle second metal film (metal light shielding film) 28 formed using aluminum (Al) is electrically separated by the opening 28a formed between the adjacent second metal films 28, and the second via hole. The point connected to the first metal film 26 by the aluminum wiring in Via 2 is the same as that of the conventional example (FIG. 11). Further, the antireflection film 31 is formed on the lower first metal film 26 using TiN (titanium nitride: titanium nitride) having a low reflectance, as in the conventional example (FIG. 11). is there.

  In addition, a third interlayer insulating film 29W having a predetermined thickness is formed above the middle second metal film 28 as described later, and is in contact with the upper surface of the third interlayer insulating film 29W. The plurality of pixel electrodes 30W, which are the main parts of the pixel electrode, are formed as a thin film by separating each pixel around the rectangular shape by the electrode gap 30a, but the alignment films facing each other above the plurality of pixel electrodes 30W A liquid crystal 42 is enclosed between 41 and 43, and a transparent counter electrode 44 is opposed to the plurality of pixel electrodes 30W on the lower surface of a transparent substrate (glass substrate) 45 having light transmittance through the liquid crystal 42, In addition, it is the same as the conventional example (FIG. 11) in that the common electrode for each pixel electrode 30W is formed by using ITO (Indium Tin Oxide) or the like without being divided for each pixel.

  Here, the difference from the conventional example will be described more specifically. An antireflection film is not formed on the middle second metal film 28 formed using aluminum (Al), and aluminum (Al ) Is exposed. Therefore, the second metal film 28 has a function of reflecting the white incident light LIW incident from the transparent substrate 45 side, and is a metal light shielding film for shielding the white incident light LIW from the lower layer side. It also has functions.

On the second metal film (metal light-shielding film) 28, the third interlayer insulating film 29W is incident from the transparent substrate 45 side using insulating and transparent SiO ₂ (silicon oxide) or the like. The film is formed with a film thickness corresponding to the center wavelength of the light LIW. At this time, since the white incident light LIW incident from the transparent substrate 45 side has a wavelength (400 nm to 700 nm) in the visible light region from blue to red, the center wavelength is about 550 nm. The film thickness of the third interlayer insulating film 29W will be described later.

  Further, on the third interlayer insulating film 29W, a plurality of pixel electrodes 30W, which is the main part of this embodiment, is formed as TiN (titanium nitride: titanium nitride) or Ti (as the uppermost third metal film in the multilayer film). It is formed into a thin film with a film thickness of 10 nm or less using a metal film material such as titanium.

  In addition, one pixel electrode (third metal film) 30W among the plurality of pixel electrodes 30W is rectangular while being connected to one MOSFET (switching element) 14 via the first and second rutal films 26 and 28. The periphery of the (square shape) is separated for each pixel by the electrode gap 30a. At this time, TiN or Ti is also formed in the third via hole Via3 obtained by etching the third interlayer insulating film 29W, so that the uppermost pixel electrode (third metal film) 30W becomes the second metal film 28 in the middle stage. It is connected.

  Since the pixel electrode 30W is formed as a thin film, a part of the white incident light LIW incident from the transparent substrate 45 side is transmitted to the lower third interlayer insulating film 29W side, but the remaining incident light is transmitted. LIW is reflected. Then, a part of the incident light LIW transmitted through the pixel electrode 30W is incident on the third interlayer insulating film 29W and then reflected on the upper surface of the metal light shielding film (second metal film) 28 toward the pixel electrode 30W. The white readout light LW reflected at is passed through the third interlayer insulating film 29W and the pixel electrode 30W, and is emitted from the transparent substrate 45 side together with the readout light LW reflected at the pixel electrode 30W. Therefore, the white incident light LIW incident from the transparent substrate 45 side is reflected by the two-layer reflective films of the pixel electrode 30W and the metal light shielding film 28.

Here, as shown in FIG. 2, a metal light shielding film (second metal film) 28 is formed with a film thickness of 700 nm using aluminum (Al), and a third interlayer insulating film 29W is formed on the metal light shielding film 28. When a film thickness of 180 nm is formed using SiO ₂ and the film thickness of the pixel electrode 30W is changed using TiN on the third interlayer insulating film 29W, TiN / SiO _{2 with} respect to incident light having a center wavelength of 550 nm. As shown in FIG.

At this time, the reflectance of TiN / SiO ₂ / Al is that the incident light LIW incident from the transparent substrate 45 is formed using TiN and the pixel electrode 30W formed using TiN and the _second electrode formed using SiO ₂ . The total reflectivity reflected by the metal light-shielding film (second metal film) 28 formed using Al via the three-layer insulating film 29 is shown.

  As can be seen from FIG. 2, when the pixel electrode 30W formed using TiN has a thickness of 10 nm or less, the incident light LIW reflected by the pixel electrode 30W and the metal light shielding film (second metal film) 28 is obtained. The reflectance is 85% or more, and sufficient reflectance can be obtained. The thinner the pixel electrode 30W is, the better the reflectance is.

  Further, the sheet resistance of the pixel electrode 30W formed using TiN is 10Ω / □, while the sheet resistance of the reflective pixel electrode 30 (FIGS. 11 and 12) formed using aluminum in the conventional example is 0. Since the resistance value of the pixel electrode 30W formed using TiN is higher than that of the conventional example, however, current does not flow through the pixel electrode 30W. Is not a problem.

Further, as shown in FIG. 3, a metal light shielding film (second metal film) 28 is formed with a film thickness of 700 nm using aluminum (Al), and a third interlayer insulating film 29W is formed on the metal light shielding film 28 by SiO2. _When the film thickness of the pixel electrode 30W is varied on the third interlayer insulating film 29W using Ti, Ti / SiO ₂ / with respect to incident light having a center wavelength of 550 nm. The Al reflectance was as shown in the figure.

At this time, the reflectance of Ti / SiO ₂ / Al means that the incident light LIW having a central wavelength of 550 nm incident from the transparent substrate 45 is formed using the pixel electrode 30W formed using Ti, and the film formed using SiO ₂ . The total reflectivity reflected by the metal light-shielding film (second metal film) 28 formed using Al via the three-layer insulating film 29 is shown.

  As apparent from FIG. 3, when the film thickness of the pixel electrode 30W formed using Ti is 10 nm or less, the incident light LIW reflected by the pixel electrode 30W and the metal light shielding film (second metal film) 28 is obtained. The reflectance is 80% or more, and the reflectance is hardly reduced. The thinner the pixel electrode 30W is, the better the reflectance is. It can be seen from the figure that the reflectance does not decrease to 50% or less even when the thickness of the pixel electrode 30W formed using Ti is increased to 30 nm.

Further, as shown in FIG. 4, a metal light shielding film (second metal film) 28 is formed with a film thickness of 700 nm using aluminum (Al), and a third interlayer insulating film 29W is formed on the metal light shielding film 28 by SiO. _{When the} pixel electrode 30W is formed on the third interlayer insulating film 29W with a film thickness of 10 nm using TiN, the Ti with respect to incident light having a center wavelength of 550 nm is formed. As shown in the figure, the reflectance of / SiO ₂ / Al was obtained.

As is apparent from FIG. 4, the reflectance of Ti / SiO ₂ / Al with respect to incident light having a center wavelength of 550 nm is undulated depending on the film thickness of the third interlayer insulating film 29W using SiO _2. It can be seen that there is a film thickness that is stronger or weaker.

  Here, when a part of the white incident light LIW incident from the transparent substrate 45 side passes through the plurality of pixel electrodes 30W and enters the third interlayer insulating film 29W, a part of the white incident light LIW is changed. The thickness of the third interlayer insulating film 29W is set in accordance with the center wavelength of the white incident light LIW in order to make the second metal film (metal light-shielding film) 28 reflect well using light interference. .

  By the way, in general, when the film thickness of the formed film is d (nm), the refractive index of the film forming material is n, and the center wavelength of light is λ (nm), the reflectivity is caused by the interference of light. The following equation (1) is established.

[Equation 1]
d = Aλ / 2n (1) where A is an integer (1, 2, 3,...).

Here, the film thickness of the third interlayer insulating film 29W formed between the pixel electrode 30W and the second metal film 28 will be described. For example, when SiO ₂ is used as the film forming material of the third interlayer insulating film 29W. The refractive index n of SiO ₂ is 1.46, and the center wavelength of the white incident light LIW is λ = 550 nm as described above. Therefore, the film thickness of the third interlayer insulating film 29W is approximately 188 nm when A = 1, approximately 377 nm when A = 2, approximately 564 nm when A = 3, and is approximately 564 nm when A = 3. Although the value of A can be increased, when the wavelength of the white incident light LIW is 400 nm to 700 nm, light leakage can be prevented by setting the film thickness of the third interlayer insulating film 29W to 400 nm or less. That is, from the viewpoint of attenuating the incident light LIW incident from the electrode gap 30a formed between the adjacent pixel electrodes 30W, the film thickness of the third interlayer insulating film 29W is set to approximately 188 nm or approximately 376 nm in the calculation result. It is desirable.

Furthermore, since the third interlayer insulating film 29W formed using SiO ₂ is a dielectric film, a capacitor can be formed. At this time, the metal light-shielding film 28 and the pixel electrode 30W have different potentials, and the potential of the metal light-shielding film 28 can be fixed (for example, COM potential), and thus acts as a storage capacitor. That is, even when the area of the storage capacitor formed on the p-type Si substrate 11 becomes smaller due to pixel miniaturization and it becomes difficult to form a sufficient capacitance value, the gap between the metal light-shielding film 28 and the pixel electrode 30W is reduced. The capacitor formed in (1) functions as a storage capacitor, and the voltage drop due to the leakage current of the MOSFET 14 can be reduced.

  From the standpoint of this characteristic, the third interlayer insulating film 29W should have a small film thickness. Therefore, considering other characteristics in addition to the reflectivity, the film thickness of the third interlayer insulating film 29W has been described above (see FIG. 1) It is desirable to set the value obtained when A = 1 in the formula (approximately 188 nm).

  As described above, the plurality of pixel electrodes (third metal film) 30W are thinned to a thickness of 10 nm or less using a metal film material such as TiN or Ti, and are in contact with the upper surfaces of these pixel electrodes 30W. When the alignment film 41 is formed, as shown in an enlarged view in FIG. 5, the height of the electrode gap 30a formed between adjacent pixel electrodes 30W is equivalent to a step of 10 nm or less depending on the film thickness of the pixel electrode 30W. Therefore, the alignment film 41 formed by entering the electrode gap 30a is not affected by the step (10 nm or less) of the pixel electrode 30W, and the alignment film 41 can be formed uniformly. Thereby, the orientation of the liquid crystal 42 is not disturbed at the end of the pixel electrode 30W, and the function of transmitting (ON) or blocking (OFF) the incident light LIW and the readout light LW works well. The contrast to the readout light LW is improved.

  Further, when the pixel electrode 30W is formed into a thin film using a metal film material such as TiN or Ti, even if a part of the white incident light LIW incident from the transparent substrate 45 passes through the pixel electrode 30W. Since the incident light LIW is reflected by the pixel electrode 30W and the metal light shielding film 28, a sufficient reflectance can be secured.

  Further, the film thickness of the third interlayer insulating film 29W formed between the metal light shielding film 28 and the pixel electrode 30W is set so that the light interference effect is maximized according to the center wavelength of the white incident light LIW. Since the reflectance from the metal light-shielding film 28 increases with respect to the white incident light LIW, the luminance can be improved.

  Next, in the reflective liquid crystal display device 10W of Example 1 according to the present invention, an active matrix circuit when a plurality of the MOSFETs (switching elements) 14 are arranged in a matrix on the p-type Si substrate 11 is shown in FIG. This will be described with reference to a) and (b).

  As shown in FIGS. 6A and 6B, in the active matrix circuit 70 in the reflective liquid crystal display device 10W (FIG. 1) according to the first embodiment of the present invention, a plurality of MOSFETs (switching elements) 14 are p-type. One pixel is formed by combining one pixel electrode 30W connected to one MOSFET 14 and a storage capacitor C for the MOSFET, which are arranged in a matrix on the Si substrate (semiconductor substrate) 11, A plurality of pixel sets are arranged in a matrix on the p-type Si substrate 11.

  In order to specify one pixel among the plurality of pixels, the horizontal shift register circuit 71 and the vertical shift register circuit 75 are provided separately in the column direction and the row direction, respectively.

  First, on the horizontal shift register circuit 71 side, the signal line 73 is wired in the vertical direction via the video switch 72 for each column of pixels. Here, for convenience of illustration, one signal line 73 is provided. Only in the state connected to the horizontal shift register circuit 71 side. A video line 74 is connected to a signal line 73 provided between the horizontal shift register circuit 71 and the video switch 72. One signal line 73 is connected to the drain electrodes 18 of the plurality of MOSFETs 14 arranged in one column.

  Next, on the vertical shift register circuit 75 side, a gate line 76 is wired in the horizontal direction for each row of pixels. Here, for convenience of illustration, only one gate line 76 is provided in the vertical shift register circuit. Shown in a state connected to the 75 side. One gate line 76 is connected to the gate electrodes 16 of the plurality of MOSFETs 14 arranged in one row.

  The source electrode 20 of each MOSFET 14 is connected to one pixel electrode 30 </ b> W and the capacitor electrode 23 via the capacitor electrode contact 24 of the storage capacitor unit C. At this time, the active matrix circuit 70 applies a well-known frame inversion driving method, and the video signal is inverted to a positive polarity and a negative polarity every frame period, that is, for example, the nth frame period of the video signal is positive. Writing is negative writing in the (n + 1) th frame period. Accordingly, when a video signal is input from the signal line 73, the signal line 73 may be connected to either the drain electrode 18 or the source electrode 20 of the MOSFET 14, but here, as described above, the signal line 73 73 is connected to the drain electrode 18. When the signal line 73 is connected to the source electrode 20, one pixel electrode 30 </ b> W and the capacitor electrode 23 are connected to the drain electrode 18 via the capacitor electrode contact 24 of the storage capacitor portion C. is there.

  In the active matrix circuit 70 described above, a well potential supplied to the MOSFET 14 as a fixed potential and a COM (common) potential supplied to the storage capacitor C are necessary.

That is, the well potential supplied to MOSFET14 includes a gate line 76, one of the p ^- for example as a fixed potential between the well potential contact well region 12 (FIG. 1) (not shown) formed in the p ⁺ region A voltage of 0V is applied. When an n-type Si substrate is used, for example, −15 V may be applied as the well potential.

  On the other hand, the COM potential supplied to the storage capacitor unit C is, for example, 8.5 V as a fixed potential between the capacitor electrode 24 of the storage capacitor unit C and a COM (common) potential contact (not shown) on the diffusion capacitor electrode 22. Is applied. At this time, the COM potential may basically be any number of volts in order to form the storage capacitor portion C. However, if the COM potential is set to the center value (for example, 8.5 V) of the video signal, the storage capacitor portion C The voltage applied to is about half of the power supply voltage. That is, since the storage capacitor withstand voltage may be approximately half of the power supply voltage, it is possible to increase the capacitance value by reducing only the thickness of the insulating film 22 of the storage capacitor portion C. Is large, the fluctuation of the potential of the pixel electrode 30W can be reduced, which is advantageous for flicker and image sticking.

  The storage capacitor unit C accumulates electric charge according to the potential difference between the potential applied to one pixel electrode 30W and the COM potential, and holds the voltage even if one MOSFET 14 is turned off during the non-selection period. In addition, the pixel electrode 30 </ b> W has a function of continuously applying the holding voltage.

  Here, in the above active matrix circuit 70, when one pixel is driven, one video signal input from the video line 74 with the timing shifted sequentially is arranged in the column direction via the video switch 72. One MOSFET 14 that is supplied to the line 73 and that intersects with the one signal line 73 and one gate line 76 arranged in the row direction is selected and turned on.

  When a video signal is input to the selected one pixel electrode 30W via the signal line 73, it is written in the storage capacitor C in the form of electric charge, and the selected one pixel electrode 30W and the counter electrode 44 are written. A potential difference is generated in accordance with the video signal between (FIG. 1) and the optical characteristics of the liquid crystal 42 (FIG. 1) are modulated. As a result, the white incident light LIW (FIG. 1) incident from the transparent substrate 45 side is optically modulated for each pixel by the liquid crystal 42 and then reflected by the plurality of pixel electrodes 30W and the second metal film 28 (FIG. 1). Then, the white readout light LW (FIG. 1) reflected here is emitted from the transparent substrate 45 side. For this reason, unlike the transmission method, the white readout light LW corresponding to the white incident light LIW can be used nearly 100%, and the structure that can achieve both high definition and high brightness for the projected image. .

FIG. 7 is a diagram for explaining an optical system of a three-plate type reflection type liquid crystal projector to which the reflection type liquid crystal display device of Example 2 according to the present invention is applied;
FIG. 8 is a cross-sectional view schematically showing one pixel in the reflective liquid crystal display device according to the second embodiment of the present invention.
FIG. 9 shows a reflection type liquid crystal display device according to Example 2 of the present invention, in which the thickness of the third interlayer insulating film formed using SiO ₂ is varied, and (a) shows the incident light having a center wavelength of 650 nm. The reflectivity of TiN / SiO ₂ / Al is shown, (b) shows the reflectivity of TiN / SiO ₂ / Al with respect to incident light with a center wavelength of 550 nm, and (c) shows TiN / SiO _{2 with} respect to incident light with a center wavelength of 450 nm. shows the reflectance of SiO ₂ / Al,
FIG. 10 is a schematic enlarged view showing the distribution state of the alignment film in the electrode gap formed between adjacent pixel electrodes in the reflective liquid crystal display device of Example 2 according to the present invention. .

  Before describing the reflective liquid crystal display devices 10R, (10G), and (10B) of the second embodiment according to the present invention shown in FIG. 8, the three-plate system to which the reflective liquid crystal display devices 10R, 10G, and 10B are applied. The optical system of the reflective liquid crystal projector will be described with reference to FIG.

  As shown in FIG. 7, the three-plate-type reflective liquid crystal projector 80 includes three reflective liquid crystal display devices 10R, 10G, and 10B in response to red light, green light, and blue light. .

  In the three-plate reflective liquid crystal projector 80, a light source unit 85 that emits visible light (white light) and the visible light emitted from the light source unit 85 are colored into three primary colors of red light, green light, and blue light. The three primary color lights are separated and guided to the three-plate reflective liquid crystal display devices 10R, 10G, and 10B corresponding to R, G, and B, respectively, and further, the reflective liquid crystal display devices 10R, 10G, and 10B of the respective colors are used. A color separation and color synthesis optical system 90 that emits color synthesized light obtained by color-combining red light, green light, and blue light that are light-modulated according to the video signal of each color, and emitted from the color separation and color synthesis optical system 90 And a projection lens (not shown) that projects the synthesized color light.

  More specifically, the light source unit 85 includes a reflecting mirror 86 and a metal halide lamp, a xenon lamp, a halogen lamp and the like installed in the reflecting mirror 86 and emitting visible light (white light). The light source 87 used and a polarization conversion plate 88 provided in front of the light source 87 and having a transmission axis selected so as to transmit only visible s-polarized light. Therefore, when visible light from the light source 87 passes through the polarization conversion plate 88, three colors of Rs light, Gs light, and Bs light respectively corresponding to R, G, and B are incident on the color separation and color synthesis optical system 90. The

  Further, when the four first to fourth polarization beam splitters 91 to 94 are shown in plan view when viewed from the upper surface side, the color separation and color synthesis optical system 90 has the first to fourth polarization beam splitters 91 to 94. The polarization separation surfaces 91a to 94a are arranged in an X shape. At this time, the second polarization beam splitter 92 is disposed on the right side of the first polarization beam splitter 91, the third polarization beam splitter 93 is disposed above the first polarization beam splitter 91, and the second polarization beam A fourth polarizing beam splitter 94 is disposed above the beam splitter 92 and to the right of the third polarizing beam splitter 93. The first polarization beam splitter 91 side faces the polarization conversion plate 88 of the light source unit 85 through a G light polarization conversion plate 95 described later, while the fourth polarization beam splitter 94 side is a projection lens (not shown). Opposite. At this time, each of the polarization separating surfaces 91a to 94a of the first to fourth polarization beam splits 91 to 94 transmits a p-polarized light and reflects a s-polarized light in a rectangular shape. It is formed along the diagonal line.

  In addition, the first polarizing beam splitter 91 on the light source unit side where visible light from the light source unit 85 enters and the fourth polarizing beam splitter 94 on the projection lens side that emits color synthesized light are formed in a large size. In addition, the second and third polarizing beam splitters 92 and 93 are formed to be slightly smaller than the first and fourth polarizing beam splitters 91 and 94.

  Further, a reflective liquid crystal display device 10G for G light is disposed facing the right side surface of the small-sized second polarizing beam splitter 92, and is opposed to the upper surface and left side surface of the small-sized third polarizing beam splitter 93. Then, the reflection liquid crystal display device 10R for R light and the reflection liquid crystal display device 10B for B light are arranged orthogonally to each other, and each of the reflection liquid crystal display devices 10R, 10G, 10B is second, third. The size of the polarizing beam splitters 92 and 93 is reduced.

  Further, a G light polarization conversion plate 95 having a function of rotating the polarization plane of the G light by 90 ° is installed on the light incident surface of the first polarization beam splitter 91 on the light source unit 85 side. Further, between the first polarization beam splitter 91 and the third polarization beam splitter 93, an R light polarization conversion plate 96 having a function of rotating the polarization plane of the R light by 90 ° is installed. An R light polarization conversion plate 97 having a function of rotating the polarization plane of the R light by 90 ° is installed between the third polarizing beam splitter 93 and the fourth polarizing beam splitter 94. A G light polarization conversion plate 98 having a function of rotating the polarization plane of the G light by 90 ° is installed on the light exit surface of the fourth polarization beam splitter 94.

  When visible light composed of Rs light, Gs light, and Bs light of s-polarized light emitted from the light source unit 85 is incident on the first polarizing beam splitter 91 via the G light polarization conversion plate 95, each of the illustrated light sources is shown. The p-polarized Rp light is incident on the R-light reflective liquid crystal display device 10R through the optical path, the p-polarized light Gp light is incident on the G-light reflective liquid crystal display device 10G, and the B-light reflective type is displayed. The s-polarized Bs light is incident on the liquid crystal display device 10B, and after being modulated in accordance with the video signal of each color by each of the reflective liquid crystal display devices 10R, 10G, and 10B, for the G light on the fourth polarizing beam splitter 94 side. Since the color composite light obtained by combining the Rp and Gp light of the p-polarized light and the Bp light is emitted from the polarization conversion plate 98 to the projection lens (not shown) side, the color composite light having no color unevenness is displayed on a screen (not shown). To be able to project There. In addition, since there are various structural forms as the color separation and color synthesis optical system, an appropriate color separation and color synthesis optical system may be applied in the first embodiment.

  Next, as shown in FIG. 8, the reflective liquid crystal display devices 10R, (10G), and (10B) of Example 2 according to the present invention correspond to red light, (green light), and (blue light). Each color is configured exclusively, and when applied to the three-plate type reflective liquid crystal projector 80 as described above with reference to FIG. 7, visible light (white light) is generated in the reflective liquid crystal projector 80. From the transparent substrate 45 side, a red incident light LIR having a wavelength of about 600 nm to 700 nm, a green incident light LIG having a wavelength of about 500 nm to 600 nm, and a blue incident light LIB having a wavelength of about 400 nm to 500 nm are separated from the transparent substrate 45 side. Each color light is incident.

  Along with this, in the reflective liquid crystal display devices 10R, (10G), and (10B), corresponding to red light, (green light), and (blue light), a portion configured exclusively for each color light The auxiliary codes of R, (G), (B) are attached after the reference numerals, and the third interlayer insulating films 29R, (29G), (29B), which are different from the first embodiment, and the pixel electrodes 30R, ( 30G) and (30B) will be mainly described below.

  First, in the multilayer film laminated above the p-type Si substrate 11, the first interlayer insulating film 25 to the first metal film 26, the second interlayer insulating film 27, and the second metal film (metal light-shielding film) 28 are conventional. As in the example (FIG. 11), the film is formed regardless of each color light, and the second metal film (metal light shielding film) 28 is formed using aluminum.

  Unlike the first embodiment, the third interlayer insulating films 29R, (29G), and (29B) formed on the second metal film (metal light shielding film) 28 are red light, (green light), and (blue light). Are formed exclusively for each color corresponding to the light), and each part of the incident light LIR, (LIG), (LIB) transmitted through the pixel electrodes 30R, (30G), (30B) is subjected to light interference. In order to use the second metal film (metal light-shielding film) 28 for good reflection, the film thicknesses of the third interlayer insulating films 29R, 29G, and 29B are set to the center wavelength of the red incident light LIR, This is set based on the equation (1) described in the first embodiment according to (center wavelength of green incident light LIG) and (center wavelength of blue incident light LIB).

Here, the respective film thicknesses of the third interlayer insulating films 29R, 29G, and 29B will be described. When SiO ₂ is used as the film forming material of the third interlayer insulating films 29R, 29G, and 29B, for example, the refractive index n of SiO ₂ Is 1.46, the center wavelength of the red incident light LIR having a wavelength of about 600 nm to 700 nm is λ = 650 nm, and the center wavelength of the green incident light LIG having a wavelength of about 500 nm to 600 nm is λ = 550 nm. The center wavelength of the blue incident light LIB having a wavelength of about 400 nm to 500 nm is λ = 450 nm.

  Accordingly, the film thickness of the third interlayer insulating film 29R corresponding to the red incident light LIR having a center wavelength of 650 nm is approximately 223 nm when A = 1 and approximately 445 nm when A = 2, according to the above-described equation (1). When A = 3, the value is approximately 668 nm, and the value of A can be increased. However, if the thickness of the third interlayer insulating film 29R is set to be equal to or less than the wavelength of the red incident light LIR, Incident light LIR that has entered through the electrode gap 30a formed between the matching pixel electrodes 30R and reached the third interlayer insulating film 29R is absorbed or reflected by the pixel electrode 30R and the metal light-shielding film (second metal film) 28. Therefore, it is possible to efficiently prevent the light leakage phenomenon in which the incident light LIR is mixed into the lower MOSFET 14.

  The film thickness of the third interlayer insulating film 29G corresponding to the green incident light LIG having a center wavelength of 550 nm is approximately 188 nm when A = 1 and approximately 377 nm when A = 2 according to the above-described equation (1). When A = 3, the thickness is approximately 564 nm. As described above, the thickness of the third interlayer insulating film 29G may be set to be equal to or less than the wavelength of the green incident light LIG.

  The film thickness of the third interlayer insulating film 29B corresponding to the blue incident light LIB having a center wavelength of 450 nm is approximately 154 nm when A = 1 and approximately 308 nm when A = 2, according to the above-described equation (1). However, when A = 3, the thickness is approximately 462 nm. As described above, the thickness of the third interlayer insulating film 29B may be set to be equal to or less than the wavelength of the blue incident light LIB.

  Furthermore, light leakage can be prevented by setting each film thickness of the third interlayer insulating films 29R, 29G, and 29B to 400 nm or less, but between the metal light shielding film 28 and the pixel electrodes 30R, 30G, and 30B. Taking into account the characteristics such as the formed storage capacitance, the thicknesses of the third interlayer insulating films 29R, 29G, and 29B are the values obtained when A = 1 in the above-described equation (1). It is desirable to set (approximately 223 nm, approximately 188 nm, approximately 154 nm).

Here, as shown in FIG. 9A, a metal light shielding film (second metal film) 28 is formed with a film thickness of 700 nm using aluminum (Al), and a third interlayer insulating film is formed on the metal light shielding film 28. When the film 29R is formed by changing the film thickness using SiO ₂ and the pixel electrode 30R is formed by using TiN with a film thickness of 10 nm on the third interlayer insulating film 29R, the center wavelength is 650 nm. The reflectivity of TiN / SiO ₂ / Al for each incident light gave the results shown in the figure.

FIG. 9B shows the case where the third interlayer insulating film 29G is formed on the metal light-shielding film 28 having a film thickness of 700 nm using aluminum (Al) with a variable film thickness using SiO _2. In addition, the reflectance of TiN / SiO ₂ / Al for each incident light having a center wavelength of 550 nm was simulated to obtain the result shown in the figure.

FIG. 9C shows a case where the third interlayer insulating film 29B is formed on the metal light-shielding film 28 having a film thickness of 700 nm using aluminum (Al) with a variable film thickness using SiO _2. In addition, the reflectance of TiN / SiO ₂ / Al with respect to each incident light having a center wavelength of 450 nm was simulated, and the result shown in the figure was obtained.

As is apparent from FIGS. 9A to 9C, the TiN / SiO ₂ / Al reflectivity with respect to each incident light having a center wavelength of 650 nm, 550 nm, and 450 is determined by the third interlayer insulation using SiO _2. It can be seen that the films 29R, 29G, and 29B are wavy depending on the film thickness, and that there is a film thickness that increases or weakens the light.

  Next, the pixel electrodes 30R, (30G), and (30B) formed for the respective colors as the third metal film on the third interlayer insulating films 29R, (29G), and (29B) are the same as in the first embodiment. , TiN, Ti, or other metal film material is used, and a plurality of the films are formed by being separated for each pixel with a film thickness of 10 nm or less.

  Since the pixel electrodes 30R, (30G), and (30B) described above are formed in a thin film, a part of incident light LIR, (LIG), and (LIB) incident for each color from the transparent substrate 45 side is downward. Although the light is transmitted to the third interlayer insulating films 29R, (29G), and (29B), the remaining incident light LIR, (LIG), and (LIB) are reflected. Then, a part of incident light LIR, (LIG), (LIB) transmitted through the pixel electrodes 30R, (30G), (30B) is incident on the third interlayer insulating films 29R, (29G), (29B). Later, the reading light LR, (LG), (LB) reflected on the pixel electrode pixel electrodes 30R, (30G), (30B) side on the upper surface of the metal light shielding film 28 is reflected on the third interlayer insulating film. Read light LR, (LG), 29R, (29G), (29B) and the pixel electrodes 30R, (30G), (30B) are reflected by the pixel electrodes 30R, (30G), (30B). The light is emitted from the transparent substrate 45 side together with (LB). Therefore, the incident light LIR, (LIG), (LIB) incident for each color from the transparent substrate 45 side is reflected by the two reflective films of the pixel electrodes 30R, (30G), (30B) and the metal light shielding film 28. Will come to be.

  Then, as described above, the pixel electrodes 30R, (30G), (30B) formed in plural for each color are thinned using a metal film material such as TiN or Ti, and the pixel electrodes 30R, (30G) are formed. ), (30B), when the alignment film 41 is formed in contact with each other, as shown in an enlarged view in FIG. 10, the electrode gap 30a formed between the adjacent pixel electrodes 30R, (30G), (30B). Is equivalent to a step of 10 nm or less depending on the film thickness of the pixel electrodes 30R, (30G), and (30B). Therefore, the alignment film 41 that is formed to penetrate into the electrode gap 30a is formed in the pixel electrode 30R. , (30G), (30B), and the alignment film 41 can be formed uniformly without being affected by the step (10 nm or less). Thereby, the orientation of the liquid crystal 42 is not disturbed at the ends of the pixel electrodes 30R, (30G), (30B), and the incident lights LIR, (LIG), (LIB) and the readout lights LR, (LG), Since the function of transmitting (ON) or blocking (OFF) with respect to (LB) works well, the contrast to the readout lights LR, (LG), (LB) is improved.

  Further, when the pixel electrodes 30R, (30G), (30B) are formed into a thin film using a metal film material such as TiN or Ti, incident light LIR, (LIG), Even if a part of (LIB) transmits through the pixel electrodes 30R, (30G), and (30B), the incident light LIR, (LIG), and (LIB) does not pass through the pixel electrodes 30R, (30G), (30B), and Since the light is reflected by the metal light-shielding film 28, a sufficient reflectance can be secured.

  Further, the thicknesses of the third interlayer insulating films 29R, (29G), and (29B) formed between the metal light shielding film 28 and the pixel electrodes 30R, (30G), and (30B) are set to the incident light LIR, (LIG ) And (LIB) are set according to the center wavelengths, respectively, and the reflectance to the metal light-shielding film 28 increases with respect to the incident light LIR, (LIG) and (LIB), so that the luminance can be improved.

In the reflective liquid crystal display device of Example 1 according to the present invention, it is a cross-sectional view schematically showing one pixel enlarged. In the reflective liquid crystal display device of Example 1 according to the present invention, when the film thickness of the pixel electrode formed using TiN is varied, the reflectance of TiN / SiO ₂ / Al with respect to incident light having a center wavelength of 550 nm is obtained. FIG. In the reflective liquid crystal display device of Example 1 according to the present invention, when the film thickness of the pixel electrode formed using Ti is varied, the reflectance of Ti / SiO ₂ / Al with respect to incident light having a center wavelength of 550 nm is obtained. FIG. In the reflective liquid crystal display device of Example 1 according to the present invention, when the film thickness of the third interlayer insulating film formed using SiO ₂ is varied, TiN / SiO ₂ / Al for incident light having a center wavelength of 550 nm. It is the figure which showed the reflectance. In the reflective liquid crystal display device of Example 1 according to the present invention, it is a diagram schematically showing a film-forming distribution state of an alignment film in an electrode gap formed between adjacent pixel electrodes. (A) is a block diagram for demonstrating the active matrix circuit in the reflection type liquid crystal display device of Example 1 which concerns on this invention, (b) is the schematic diagram which expanded and showed X part in (a) It is. It is a figure for demonstrating the optical system of the reflection type liquid crystal projector of the 3 plate system to which the reflection type liquid crystal display device of Example 2 which concerns on this invention is applied. In the reflective liquid crystal display device of Example 2 which concerns on this invention, it is sectional drawing which expanded and showed one pixel typically. In the reflective liquid crystal display device according to Example 2 of the present invention, when the thickness of the third interlayer insulating film formed using SiO ₂ is varied, (a) shows TiN / SiO for incident light having a center wavelength of 650 nm. shows the reflectance of ₂ / Al, (b) shows the reflectivity of TiN / _SiO 2 / Al center wavelength to incident light of 550nm, (c) TiN central wavelength is to incident light of 450 nm / _SiO 2 / It is the figure which showed the reflectance of Al. In the reflective liquid crystal display device of Example 2 according to the present invention, it is a diagram schematically showing an enlarged distribution state of an alignment film in an electrode gap formed between adjacent pixel electrodes. In the reflective liquid crystal display device of the conventional example, it is sectional drawing which expanded and showed one pixel typically. In the reflective liquid crystal display device of the conventional example, it is the figure which expanded typically and showed the film-forming distribution state of the alignment film in the electrode gap | interval formed between adjacent reflective pixel electrodes.

Explanation of symbols

10 W: reflective liquid crystal display device of Example 1,
10R, 10G, 10B ... reflection type liquid crystal display device of Example 2,
11 ... Semiconductor substrate (p-type Si substrate), 12 ... p ^- well region,
13A to 13C: Field oxide film,
14 ... switching element (MOSFET), 15 ... gate oxide film,
16 ... gate electrode, 17 ... drain region, 18 ... drain electrode,
19 ... source region, 20 ... source electrode,
21 ... diffusion capacitance electrode, 22 ... insulating film, 23 ... capacitance electrode,
24: Contact for capacitive electrode,
25-30 ... multilayer film,
25 ... 1st interlayer insulation film, 26 ... 1st metal film, 27 ... 2nd interlayer insulation film,
28 ... Metal light shielding film (second metal film), 28a ... Opening,
29W ... Third interlayer insulating film of Example 1,
29R, 29G, 29B ... third interlayer insulating film of Example 2,
30 W: pixel electrode (third metal film) of Example 1, 30 a: electrode gap,
30R, 30G, 30B ... pixel electrode (third metal film) of Example 2,
31, 32 ... antireflection film,
41 ... Alignment film, 42 ... Liquid crystal, 43 ... Alignment film,
44 ... Transparent counter electrode, 45 ... Transparent substrate (glass substrate),
70: Active matrix circuit,
71 ... Horizontal shift register circuit, 72 ... Video switch, 73 ... Signal line,
74 ... Video line, 75 ... Vertical shift register circuit, 76 ... Gate line,
C1 to C3 ... holding capacity part,
D ... Drain, G ... Gate, S ... Source,
Via1 to Via3 ... first to third via holes,
LIW: incident light in the first embodiment, LW: readout light in the first embodiment,
LIR, LIG, LIB ... incident light in Example 2,
LR, LG, LB: reading light in the second embodiment.

Claims (3)

A plurality of switching elements formed for each pixel on a semiconductor substrate;
Among the multilayer films stacked above the plurality of switching elements, the uppermost layer is connected to each switching element, and the periphery of the rectangle is separated for each pixel by an electrode gap, and a part of incident light is transmitted. And a plurality of pixel electrodes formed in a thin film using a metal film material to reflect the remaining incident light,
In the multilayer film, the plurality of pixel electrodes are formed below the plurality of pixel electrodes with an interlayer insulating film interposed therebetween, and the plurality of incident lights transmitted through the plurality of pixel electrodes are shielded against a lower layer side. A metal light-shielding film that reflects to the pixel electrode side;
A transparent counter electrode formed on a transparent substrate;
The plurality of pixel electrodes and the transparent counter electrode are opposed to each other, and the liquid crystal is sealed with an alignment film facing each other between the electrodes.
The incident light incident from the transparent substrate side is optically modulated by the liquid crystal in accordance with a signal from each switching element, and then reflected by the plurality of pixel electrodes and the metal light-shielding film. A reflection type liquid crystal display device configured to emit readout light from a liquid crystal display. The reflective liquid crystal display device according to claim 1,
The reflection type liquid crystal display device, wherein the plurality of pixel electrodes are formed with a film thickness of 10 nm or less using TiN or Ti as the metal film material. The reflective liquid crystal display device according to claim 1 or 2,
A reflective liquid crystal display device, wherein a film thickness of the interlayer insulating film formed between the plurality of pixel electrodes and the metal light shielding film is set according to a center wavelength of the incident light.

Images