JP4197046B2 - Substrate for liquid crystal panel, liquid crystal panel, electronic device and projection display device - Google Patents

Description

  The present invention relates to a liquid crystal panel substrate, and further to a reflective liquid crystal panel configured using the substrate, and is particularly suitable for use in an active matrix liquid crystal panel in which pixel electrodes are switched by switching elements formed on the substrate. Technology. The present invention also relates to an electronic apparatus and a projection display device using the liquid crystal panel.

  Conventionally, as an active matrix liquid crystal panel used for a light valve of a projection display device, a liquid crystal panel having a structure having a thin film transistor (TFT) array using amorphous silicon as a pixel switching element on a glass substrate has been put into practical use. .

  Since the active matrix liquid crystal panel using the TFT has a low TFT element mobility and a large device size, for example, in a projection display device such as a projector in which the TFT is incorporated as a light valve, the entire device becomes large. There is a problem that it ends up. In the case of a transmissive liquid crystal panel, the area of the TFT provided in each pixel does not become the transmission area of the pixel that transmits light, so that the aperture ratio decreases as the panel resolution increases to XGA and SXGA. Have certain flaws.

  Therefore, as a liquid crystal panel that is smaller in size than a transmissive active matrix liquid crystal panel, an insulated gate field effect transistor (MOSFET) array formed on a semiconductor substrate is used as a switching element to control the voltage applied to the pixel electrode serving as a reflective electrode. There is a reflection type active matrix liquid crystal panel designed to do this.

  As described above, in an active matrix liquid crystal panel in which transistor elements are formed on a glass or semiconductor substrate, when light leaks from the gap between each pixel electrode, the PN junction (transistor source / transistor in the semiconductor substrate or the semiconductor substrate). Electron and hole pairs are generated at the junction of the drain region and the channel region, the junction of the source / drain region and the well, etc., and the light leakage current flows and the potential of the semiconductor layer, semiconductor substrate or well becomes unstable. There is a problem of becoming. In the case of the reflective type, for example, by forming pixel electrodes on the uppermost layer and providing the pixel electrodes close to each other, the amount of light leakage can be reduced as compared with the transmissive type without any particular measures against light shielding. However, in the reflective liquid crystal panel used for the light valve of the projection display device, strong light is collected, so that strong light also enters the gap between the pixel electrodes. It is not a sufficient measure.

  In particular, since a liquid crystal panel using a semiconductor as a substrate has a well region, a light leakage current may flow only when light leaks not only through the transistor portion but also through a semiconductor substrate away from the transistor portion. For this reason, unless a firm countermeasure against light leakage is taken, there is a drawback that this light leakage current becomes larger than that of a liquid crystal panel in which TFTs as switching elements are arranged on a glass substrate.

  Further, in an active matrix liquid crystal panel in which transistor elements are formed on a glass or semiconductor substrate, peripheral circuits such as a scanning side driving circuit and a data line driving circuit are configured by transistors formed on the same substrate. Even in such a peripheral circuit, when light enters, a light leakage current is generated and the peripheral circuit malfunctions.

  Furthermore, in a reflective liquid crystal panel, an insulating film is exposed in the gap between the pixel electrode, but if the light reflected by the surface of the insulating film is directly turned 180 degrees and emitted, it is displayed as extra light. As a result, the image quality is degraded.

  An object of the present invention is to provide a technique capable of reducing a light leakage current generated in a substrate by reducing a light leakage amount from a gap between pixel electrodes in a reflective liquid crystal panel.

  Another object of the present invention is to provide a reflection type liquid crystal panel in which a peripheral circuit is provided outside a pixel region in which pixel electrodes are arranged in a matrix, without increasing the number of process steps. The object is to provide a technique capable of reducing the amount of light leakage.

  Another object of the present invention is to provide a technique capable of preventing an adverse effect on display image quality caused by reflected light on the surface of an insulating film exposed in a gap between a pixel electrode in a reflective liquid crystal panel. There is.

In order to achieve the above object, according to the present invention, a substrate for a liquid crystal panel according to the present invention includes a unit pixel having a pixel electrode serving as a reflective electrode and a switching element provided corresponding to the pixel electrode in a matrix form. A first light-shielding layer covering a region between adjacent pixel electrodes in a pixel region in which the unit pixels are arranged in a matrix , and the pixel electrode, the switching element, and the switching element; An interlayer insulating film is disposed between the pixel electrode and the first light shielding layer, and a silicon nitride film is formed on the pixel electrode side of the interlayer insulating film, and the silicon nitride film above and antireflection film between the pixel electrode is formed, a peripheral region arranged outside the pixel region, the formed simultaneously with the pixel electrode of the same metal layer A light shielding layer and a third light shielding layer formed simultaneously with the first light shielding layer from the same metal layer, and the interlayer insulating film is disposed between the second light shielding layer and the third light shielding layer. It is characterized by being. This not only improves the moisture resistance against the ingress of water or the like, but also because the refractive index of silicon nitride is high, when light is incident from the liquid crystal side, the incident light can be reflected and shielded. Furthermore, by providing an antireflection film between the pixel electrode and the light shielding layer, the light shielding property can be further improved .

Further, in a liquid crystal panel substrate in which unit pixels having pixel electrodes to be reflective electrodes and switching elements provided corresponding to the pixel electrodes are arranged in a matrix on the substrate, between the adjacent pixel electrodes A first light-shielding layer is provided between the pixel electrode and the switching element, and an interlayer insulating film is disposed between the pixel electrode and the first light-shielding layer. A silicon nitride film is formed on the pixel electrode side of the insulating film, an antireflection film is formed between the silicon nitride film and the pixel electrode, and the interlayer insulating film or the first light shielding layer is A groove having at least a slope is formed in a region between adjacent pixel electrodes.
Further, in a liquid crystal panel substrate in which unit pixels having pixel electrodes to be reflective electrodes and switching elements provided corresponding to the pixel electrodes are arranged in a matrix on the substrate, between the adjacent pixel electrodes A first light-shielding layer is provided between the pixel electrode and the switching element, and an interlayer insulating film is disposed between the pixel electrode and the first light-shielding layer. A silicon nitride film is formed on the pixel electrode side of the insulating film, an antireflection film is formed between the silicon nitride film and the pixel electrode, and the interlayer insulating film has a TEOS film It is characterized by.

  Further, the antireflection film is provided in a lower layer of the pixel electrode.
  Further, the antireflection film should not be provided on the surface of the light shielding layer or in the interlayer insulating film.
The
  Moreover, the liquid crystal panel of the present invention is opposed to the liquid crystal panel substrate according to any one of the above.
The liquid crystal is sandwiched between the substrate and the substrate.

  Furthermore, an electronic apparatus according to the present invention includes the liquid crystal panel as a display unit.
.

  Further, the projection display device of the present invention modulates light from the light source, the light source, and the light source.
The above-mentioned liquid crystal panel and a projection optical hand for condensing and projecting light modulated by the liquid crystal panel
And a step.

In addition, a liquid crystal panel substrate according to a reference example for achieving the above-described object is provided with an image serving as a reflective electrode.
A unit pixel having an element electrode and a switching element that controls voltage application to the pixel electrode is based on the unit pixel.
In a liquid crystal panel substrate arranged in a matrix on a plate, the pixel electrode and the spacer
It has an opening surrounding the connection conductor formation point for electrically connecting the switching element, and is adjacent to it.
A light-shielding layer having no opening in a region between the plurality of pixel electrodes.
An interlayer insulating film is disposed between the pixel electrode and the light shielding layer.
An inclined surface facing the surface of the light shielding layer in a region between the adjacent pixel electrodes.
It is characterized by forming a V-shaped groove having
Further, an antireflection film is provided between the pixel electrode and the light shielding layer,
Further, the antireflection film is provided on the lower surface of the pixel electrode.

Further, the antireflection film is provided on the surface of the light shielding layer or in the middle of the interlayer insulating film.
It is characterized by that.

More specifically, the features of the reference example are summarized as follows.

  First, in a liquid crystal panel substrate in which pixel units each including a pixel electrode serving as a reflective electrode and a switching element that controls voltage application to the pixel electrode are arranged in a matrix on the substrate, the pixel electrode A contact hole for connecting the pixel electrode and the terminal electrode is formed between the conductive layer constituting the terminal electrode of the switching element, and an opening surrounding the contact hole forming portion is formed adjacent to the contact hole. A light-shielding layer having no opening is provided between the pixel electrode and the conductive layer in a region between the plurality of pixel electrodes. Thus, the amount of incident light that leaks through the gap between the pixel electrodes and leaks to the switching element can be made substantially zero.

  Second, an antireflection film is provided between the pixel electrode and the light shielding layer. As a result, when the light shielding layer is made of a metal layer having a relatively high reflectance such as aluminum, the light incident on the gap between the pixel electrodes can be absorbed by the surface of the light shielding layer.

  Third, an antireflection film having substantially the same shape as the pixel electrode is disposed on the lower surface of the pixel electrode. As a result, the light incident on the gap between the pixel electrodes is repeatedly reflected between the surface of the light shielding layer and the back surface of the pixel electrode, and from the opening provided in the connection conductor forming portion that connects the pixel electrode and the switching element. It is possible to prevent light from leaking to the switching element side and reaching the semiconductor layer or the semiconductor substrate, thereby preventing a light leak current from flowing.

  Fourth, the antireflection film is made of titanium nitride. Titanium nitride has good adhesion to a pixel electrode such as Al and also has good light absorption.

  Fifth, the thickness of the titanium nitride is 500 to 1000 angstroms. The upper range is preferable as the film thickness for absorbing visible light.

  Sixth, in a region between a plurality of adjacent pixel electrodes, a groove having at least a slope is formed on the surface of the lower insulating film of the pixel electrode or on the surface of the light shielding layer below the lower insulating film. It is characterized by. As a result, the light incident from the gap between the pixel electrodes can be reflected in an oblique direction, so that the light incident from the gap is reflected by the light shielding layer and is emitted again from the gap, and this light is reflected in the reflected light from the pixel electrode. It can prevent mixing. As a result, the contrast of the liquid crystal panel can be improved.

    Seventh, an antireflection film having substantially the same shape as the pixel electrode is disposed on the lower surface of the pixel electrode. As a result, light that is absorbed by the antireflection film on the back side of the pixel electrode and reflected by the surface of the insulating film exposed in the gap between the pixel electrodes or the light shielding layer therebelow is prevented from being output after being turned 180 degrees as it is. Thus, the display image quality can be improved.

  Eighth, the antireflection film is made of titanium nitride.

  Ninth, the thickness of the titanium nitride is 500 to 1000 angstroms. These effects are the same as the fourth and fifth effects.

  Tenth, the contact hole is provided at a position substantially at the center of the planar shape of the pixel electrode. As a result, the distance from the end of each pixel electrode (gap between the pixel electrodes) to the opening provided in the light shielding layer is substantially evenly separated from each end, so that light incident from the gap between the pixel electrodes is blocked by the light shielding layer. The distance to reach the opening becomes longer, making it difficult for light to reach the switching element side.

  Eleventh, in a liquid crystal panel substrate in which pixel units each including a pixel electrode serving as a reflective electrode and a switching element that controls voltage application to the pixel electrode are arranged in a matrix on the substrate, a plurality of the pixels A pixel region composed of units and a peripheral circuit disposed in a peripheral region of the pixel region are configured on the same substrate, and a light shielding layer configured by the same layer as the reflective electrode in the pixel region It is provided above the circuit. Thereby, the amount of light leakage in the pixel region and the peripheral circuit can be reduced without increasing the number of steps of the manufacturing process of the liquid crystal panel substrate.

  12thly, the said light shielding layer is arrange | positioned in the peripheral region surrounding the perimeter of the said pixel area | region including the area | region where the said peripheral circuit is not arrange | positioned. The pixel electrode may be disposed around the pixel region and serve as a “parting”.

  13thly, in the said pixel area, the 2nd light shielding layer is arrange | positioned between the said pixel electrode and the said switching element, and the 1st light shielding layer arrange | positioned above the said peripheral circuit and the most in the said pixel area. The second light shielding layer is arranged in a region between the outer end and the pixel electrode. In the pixel region, the second light shielding layer disposed under the pixel electrode can prevent light from entering from the boundary between the pixel region and the peripheral circuit region.

  Fourteenth, a contact hole for connecting the pixel electrode and the terminal electrode is formed between the pixel electrode and a conductive layer constituting the terminal electrode of the switching element. A second light-shielding layer having an opening surrounding a contact hole forming portion and having no opening in a region between a plurality of adjacent pixel electrodes is provided between the pixel electrode and the conductive layer. Thus, in the peripheral circuit, the second light shielding layer is disposed below the first light shielding layer, and the second light shielding layer is used as a connection wiring portion in the peripheral circuit. As a result, the peripheral circuit portion can be multi-layered using the light shielding layer in the pixel region, and the drive circuit and the like can be highly integrated.

  15th, The said 2nd light shielding layer has the light shielding part extended from the said connection wiring part, or isolate | separated from the said connection wiring part. Thus, the peripheral circuit is protected from light by the two light shielding layers.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

(Description of substrate for liquid crystal panel using semiconductor substrate)
1 and 3 show a first embodiment of a reflective electrode side substrate of a reflective liquid crystal panel to which the present invention is applied. 1 and 3 show a cross-sectional view and a planar layout of one pixel portion among pixels arranged in a matrix. FIG. 1A shows a cross section taken along line II in FIG. FIG.1 (b) shows the cross section along the II-II line in FIG. 3 similarly.

In FIG. 1, 1 is a P-type semiconductor substrate (N-type semiconductor substrate (N ⁻ )) such as single crystal silicon, 2 is a P-type well region formed on the surface of the semiconductor substrate 1, and 3 is a semiconductor substrate. 1 is a field oxide film (so-called LOCOS) for element isolation formed on the surface of 1. The well region 2 is not particularly limited, but is formed as a common well region of a pixel region in which pixels are arranged in a matrix such as 768 × 1024. Transistors constituting peripheral circuits such as a data line driving circuit 21, a gate line driving circuit 22, an input circuit 23, and a timing control circuit 24 as shown in FIG. 5 showing a plan view of the entire liquid crystal panel substrate. It may be formed separately from the well region where the element is formed.

  A phenomenon in which carriers generated in a well region where an element of a peripheral circuit operated by a high-frequency clock flows into the well region of the pixel region and the pixel transistor malfunctions can be prevented by well separation. Further, the separation of wells can also prevent the influence of external static noise entering the well region from the input circuit 23 and the noise entering the well of the pixel region and causing the pixel transistor to malfunction.

  The field oxide film 3 is formed to a thickness of 5000 to 7000 angstroms by selective thermal oxidation. In the field oxide film 3, two openings are formed for each pixel, and a gate electrode 4a made of polysilicon, metal silicide, or the like is formed at the inner center of one of the openings via a gate oxide film (insulating film) 4b. Source and drain regions 5a and 5b made of high impurity concentration N-type impurity introduction layers (hereinafter referred to as doping layers) are formed on the surface of the substrate on both sides of the gate electrode 4a. A transistor (MOSFET) is configured. The gate electrode 4 a extends in the scanning line direction (pixel row direction) to form the gate line 4.

  A P-type doping region 8 is formed on the surface of the substrate inside the other opening formed in the field oxide film 3, and the surface of the P-type doping region 8 is interposed via an insulating film 9b. An electrode 9 a made of polysilicon or metal silicide is formed, and an insulating film capacitance is formed between the electrode 9 a and the P-type doping region 8. The electrode 9a is formed in the same process as the polysilicon or metal silicide layer used as the gate electrode 4a of the MOSFET, and the insulating film 9b under the electrode 9a is formed in the same process as the insulating film used as the gate insulating film 4b. be able to.

  The insulating films 4b and 9b are formed on the inner semiconductor substrate surface of the opening to a thickness of 400 to 800 angstroms by thermal oxidation. In the electrodes 4a and 9a, a polysilicon layer is formed to a thickness of 1000 to 2000 angstroms, and a refractory metal silicide layer such as Mo or W is formed to a thickness of 1000 to 3000 angstroms thereon. It is made the structure. The source / drain regions 5a and 5b are formed in a self-aligned manner by implanting N-type impurities by ion implantation into the substrate surface on both sides of the gate electrode 4a as a mask. The well region immediately below the gate electrode 4a becomes a channel region 5c of the MOSFET.

The P-type doping region 8 may be formed by, for example, a dedicated ion implantation and doping treatment by heat treatment, and may be formed by an ion implantation method before forming the gate electrode. That is, after forming the insulating films 4b and 9b, impurities having the same polarity as the well are implanted, and the surface of the well is formed with a higher impurity concentration and lower resistance than the well. A preferable impurity concentration of the well region 2 is 1 × 10 ¹⁷ / cm ³ or less, and preferably about 1 × 10 ^{16 to} 5 × 10 ¹⁶ / cm ³ . The preferred surface impurity concentration of the source / drain regions 5a and 5b is 1 × 10 ^{20 to} 3 × 10 ²⁰ / cm ³ , and the preferred surface impurity concentration of the P-type doping region 8 is 1 × 10 ^{18 to} 5 × 10 ¹⁹ / cm ³ . However, 1 × 10 ¹⁸ to 1 × 10 ¹⁹ / cm ³ is particularly preferable from the viewpoint of the reliability and breakdown voltage of the insulating film constituting the storage capacitor.

  A first interlayer insulating film 6 is formed from the electrodes 4a and 9a to the field oxide film 3, and a data line 7 (see FIG. 3) made of a metal layer mainly composed of aluminum is formed on the insulating film 6. A source electrode 7 a and an auxiliary coupling wiring 10 formed so as to protrude from the data line are provided. The source electrode 7 a is formed in the source region 5 a through a contact hole 6 a formed in the insulating film 6, and the auxiliary coupling wiring 10. One end is electrically connected to the drain region 5b through a contact hole 6b formed in the insulating film 6, and the other end is electrically connected to the electrode 9a through a contact hole 6c formed in the insulating film 6. Yes.

  As the insulating film 6, for example, an HTO film (silicon oxide film formed by a high-temperature CVD method) is deposited to about 1000 angstroms, and a BPSG film (silicate glass film containing boron and phosphorus) is 8000 to 10,000 angstroms. It is deposited to a thickness. The metal layer constituting the source electrode 7a (data line 7) and the auxiliary coupling wiring 10 has, for example, a four-layer structure of Ti / TiN / Al / TiN from the lower layer. Each layer has a thickness such that the lower Ti layer is 100 to 600 angstroms, the TiN layer is about 1000 angstroms, the Al layer is 4000 to 10000 angstroms, and the upper TiN layer is 300 to 600 angstroms.

  A second interlayer insulating film 11 is formed on the interlayer insulating film 6 from the source electrode 7a and the auxiliary coupling wiring 10, and a second metal layer 12 mainly composed of aluminum is formed on the second interlayer insulating film 11. A light shielding layer (light shielding layer) is formed. The second metal layer 12 constituting the light shielding layer is also formed as a metal layer constituting connection wiring between elements in a peripheral circuit such as a drive circuit formed around the pixel region as described later. Is. Therefore, it is not necessary to add a process to form only the light shielding layer 12, and the process is simplified. Further, the light shielding layer 12 is formed with an opening 12a through which a columnar connection plug 15 for electrically connecting a pixel electrode and a MOSFET, which will be described later, penetrates at a position corresponding to the auxiliary coupling wiring 10. The others are formed so as to cover the entire pixel region. That is, in the plan view shown in FIG. 3, a rectangular frame denoted by reference numeral 12 a represents the opening, and the outside of the opening 12 a is the light shielding layer 12. Thereby, light incident from above (the liquid crystal layer side) in FIG. 1 is almost completely blocked to prevent light leaking from flowing into the channel region and well region of the switching MOSFET of the pixel. it can.

  The second interlayer insulating film 11 is formed, for example, by depositing a silicon oxide film (hereinafter referred to as a TEOS film) formed by a plasma CVD method using TEOS (tetraethyl orthosilicate) as a material to a thickness of about 3000 to 6000 angstroms. (Spin-on-glass film) is deposited, etched by etchback, and then a second TEOS film is deposited thereon to a thickness of about 2000 to 5000 angstroms. The second metal layer 12 constituting the light shielding layer may be the same as the first metal layer 7 (7a), for example, a four-layer structure of Ti / TiN / Al / TiN from the lower layer. Each layer has a thickness such that the lowermost layer of Ti is 100 to 600 angstroms, the upper TiN layer is about 1000 angstroms, Al is about 4000 to 10000 angstroms, and the uppermost layer of TiN is 300 to 600 angstroms.

  In this embodiment, a third interlayer insulating film 13 is formed on the light shielding layer 12, and a rectangular shape corresponding to one pixel is formed on the third interlayer insulating film 13 as shown in FIG. A pixel electrode 14 to be a reflective electrode having a shape is formed. A contact hole 16 penetrating through the third interlayer insulating film 13 and the second interlayer insulating film 11 is provided so as to be located inside the opening 12a provided in the light shielding layer 12. The contact hole 16 is filled with a columnar connection plug 15 made of a refractory metal such as tungsten for electrically connecting the auxiliary coupling wiring 10 and the pixel electrode 14. Further, a passivation film 17 is formed on the entire surface of the pixel electrode 14.

  When a liquid crystal panel is configured, an alignment film is further formed on the reflective electrode side substrate, and the counter substrate is disposed opposite to the substrate with a predetermined gap so as to face the substrate. A counter electrode (common electrode) is previously formed on the inner surface of the counter substrate, and an alignment film is formed thereon. Further, the peripheral portions of the pair of substrates are bonded and fixed with a sealing material, and liquid crystal is filled and sealed in a gap formed thereby, thereby forming a liquid crystal panel.

  Although not particularly limited, after tungsten or the like constituting the connection plug 15 is deposited by a CVD method, the tungsten and the third interlayer insulating film 13 are shaved and planarized by a CMP (chemical mechanical polishing) method, and then the pixel electrode 14 is formed. For example, an aluminum layer is formed to a thickness of 300 to 5000 angstroms by, for example, a low-temperature sputtering method, and is formed into a square shape having a side of about 15 to 20 μm by patterning. As a method for forming the connection plug 15, there is a method in which the third interlayer insulating film 13 is flattened by the CMP method, a contact hole is opened, and tungsten is deposited therein. As the passivation film 17, a silicon oxide film having a thickness of 500 to 2000 angstroms is used in the pixel region, and the peripheral circuit part of the substrate and the seal part 36 and the scribe part are 2000 to 10,000 angstroms. A silicon nitride film having a proper thickness is used. Note that, as described above, the above-described seal portion indicates a formation region of a seal material for bonding and fixing a pair of substrates when a liquid crystal panel is configured. In addition, the above-mentioned scribe portion is formed along the scribe region when the reflection side liquid crystal panel substrate of the present invention is formed on a semiconductor wafer and diced into semiconductor chips to be written along the scribe line. This is a portion to be a portion (that is, an end portion of the liquid crystal panel substrate).

  In addition, by using a silicon oxide film as the passivation film 17 that covers the pixel region portion, it is possible to suppress a phenomenon in which the reflectance changes greatly due to variations in film thickness or the reflectance varies greatly depending on the wavelength of light.

  On the other hand, the passivation film 17 covering the peripheral area of the substrate, particularly the area outside the area where the liquid crystal is sealed (outside the seal member) is used as a protective film compared to the silicon oxide film in terms of the water resistance of the substrate. Reliability is further improved by using an excellent silicon nitride film and making it a single layer structure of this silicon nitride film or a protective film having a two-layer structure in which a silicon nitride film is formed on a silicon oxide film. be able to. That is, in the substrate peripheral area that is exposed to the outside air, particularly in the scribe portion, moisture and the like easily enter from there, but the portion is covered with the protective film of the silicon nitride film, so that the reliability and durability can be improved.

  As a passivation film formed on the reflective electrode, if a film thickness in the range of 500 to 2000 angstroms is obtained, a reflection-side liquid crystal panel with little wavelength dependency of reflectance by the pixel electrode can be configured. An alignment film made of polyimide is formed on the entire surface of the passivation film 17 and rubbed when a liquid crystal panel is formed.

  FIG. 3 is a plan layout diagram of the liquid crystal panel substrate on the reflection side shown in FIG. As shown in the figure, in this embodiment, the data line 7 and the gate line 4 are formed so as to cross each other. Since the gate line 4 is configured to also serve as the gate electrode 4a, the gate line 4 portion indicated by hatching H in FIG. 3 becomes the gate electrode 4a, and a channel region 5c of the pixel switching MOSFET is formed on the substrate surface below the gate line 4a. Is provided. Source and drain regions 5a and 5b are formed on the substrate surface on both sides (upper and lower in FIG. 3) of the channel region 5c. The source electrode 7a connected to the data line is formed so as to protrude from the data line 7 extending along the vertical direction of FIG. 3, and is connected to the source region 5a of the MOSFET through the contact hole. It is out.

  Further, the P-type doping region 8 constituting one terminal of the storage capacitor is formed to be continuous with the P-type doping region of the adjacent pixel in the direction parallel to the gate line 4 (pixel row direction). The power supply line 70 disposed outside the pixel region is connected to the contact hole 71 so that a predetermined voltage Vss such as 0 V (ground potential) is applied. This predetermined voltage Vss is composed of the potential of the common electrode arranged on the counter substrate or a potential in the vicinity thereof, the central potential of the amplitude of the image signal supplied to the data line, the potential in the vicinity thereof, or the common electrode potential. Any one of the intermediate potentials of the amplitude central potential of the signal potential may be used.

  By connecting the P-type doping region 8 to the voltage Vss in common outside the pixel region, the potential of one electrode of the storage capacitor is stabilized, and the storage capacitor is held during the pixel non-selection period (when the MOSFET is non-conductive). The holding potential to be stabilized can be stabilized, and the fluctuation of the potential applied to the pixel electrode in one frame period can be reduced. In addition, an undesired potential change of the pixel electrode can be prevented. Further, since the P-type doping region 8 is provided in the vicinity of the MOSFET and the potential of the P well is also fixed at the same time, the substrate potential of the MOSFET can be stabilized and fluctuations in the threshold voltage due to the back gate effect can be prevented.

  Although not shown, the power supply line 70 is also used as a line for supplying a predetermined voltage Vss as a well potential to a P-type well region of a peripheral circuit provided outside the pixel region. The power supply line 70 is formed of the same first metal layer as the data line 7. The pixel electrodes 14 each have a rectangular shape, and are adjacent to each other with an interval of, for example, 1 μm from adjacent pixel electrodes 14 so as to reduce the amount of light leaking from the gap between the pixel electrodes as much as possible. It is configured.

  In the figure, the center of the shape of the pixel electrode and the center of the contact hole 16 are shifted from each other. However, when the centers of the two are substantially matched or overlapped, light entering from the gap between the adjacent pixel electrodes enters the contact hole. The distance to reach is almost uniform from the end of the pixel electrode, which is preferable in reducing the amount of light leakage. This is because the second metal layer 12 having a light shielding function is opened at 12a around the contact hole 16, so that if there is an opening 12a near the end of the pixel electrode 14, the gap between the pixel electrodes This is because the incident light is diffusely reflected between the second metal layer 12 and the back surface of the pixel electrode 14, reaches the opening 12 a, enters the lower substrate side from the opening, and light leakage occurs. . Therefore, by making the center of the pixel electrode and the center of the contact hole 16 substantially coincide or overlap, the distance until the light entering from the gap between the adjacent pixel electrodes reaches the contact hole is substantially uniform from the end of each pixel electrode. Therefore, it is preferable because light can be made difficult to reach a contact hole where light may be incident on the substrate side.

  In the above embodiment, the case where the pixel switching MOSFET is an N-channel type and the semiconductor region 8 serving as one electrode of the storage capacitor is a P-type doping layer has been described. The switching MOSFET may be a P-channel type, and the semiconductor region serving as one electrode of the storage capacitor may be an N-type doping layer. In that case, it is desirable that a predetermined potential V DD is applied to the N-type doping layer serving as one electrode of the storage capacitor in the same manner as applied to the N-type well region. Note that the predetermined constant potential V DD is for applying a potential to the N-type well region, and is preferably a potential on the higher power supply voltage side. That is, if the voltage of the image signal applied to the source / drain of the pixel switching MOSFET is 5V, the predetermined constant potential V DD is preferably 5V.

  Further, a large voltage such as 15V is applied to the gate electrode 4a of the pixel switching MOSFET, whereas a logic circuit such as a shift register in the peripheral circuit is driven with a small voltage such as 5V ( A part of the peripheral circuit, for example, a circuit for supplying a scanning signal to the gate line is driven by 15V), so that the gate insulating film of the FET constituting the peripheral circuit operating at 5V is used as the gate insulating film of the pixel switching FET. It is made thinner (by making the gate insulating film manufacturing process a separate process, or by etching the gate insulating film surface of the peripheral circuit FET, etc.) to improve the response characteristics of the peripheral circuit FET. A technique for increasing the operation speed of peripheral circuits (particularly, a shift register of a data line side driving circuit that requires high-speed scanning) can be considered. When such a technique is applied, the thickness of the gate insulating film of the FET constituting the peripheral circuit is set to about 1/3 to 1/5 of the thickness of the gate insulating film of the pixel switching FET due to the breakdown voltage of the gate insulating film. (For example, 80 to 200 angstroms).

  Incidentally, the driving waveform in the first embodiment is as shown in FIG. In the figure, VG is a scanning signal applied to the gate electrode of the pixel switching MOSFET, and a period t H1 is a selection period (scanning period) in which the MOSFET of the pixel is made conductive. This is a non-selection period for non-conduction. Vd is the maximum amplitude of the image signal applied to the data line, Vc is the center potential of the image signal, and LC-COM is applied to the counter (common) electrode formed on the counter substrate facing the reflective electrode side substrate. Common potential.

  The voltage applied between the electrodes of the storage capacitor is determined by the difference between the image signal voltage Vd applied to the data line as shown in FIG. 7 and a predetermined voltage Vss such as 0 V applied to the P-type semiconductor region 8. . However, the potential difference that should be originally applied to the storage capacitor is about 5 V, which is the difference between the image signal voltage Vd and the center potential Vc of the image signal (applied to the counter (common) electrode 33 provided on the counter substrate 35 of the liquid crystal panel in FIG. 6). The common potential LC-COM is shifted by ΔV from Vc, but the voltage actually applied to the pixel electrode is also Vd−ΔV shifted by ΔV). Therefore, in the first embodiment, the doping region 8 constituting one terminal of the storage capacitor has a polarity opposite to that of the well (N-type in the case of a P-type well), and Vc or LC-COM is formed around the pixel region. It is also possible to connect to a nearby potential and set the potential different from the well potential (for example, Vss for a P-type well). Thus, the insulating film 9b immediately below the polysilicon or metal silicide layer constituting one electrode 9a of the storage capacitor is formed simultaneously with the gate insulating film of the FET constituting the peripheral circuit, not the gate insulating film of the pixel switching FET. Thus, the insulating film thickness of the storage capacitor can be reduced to 1/3 to 1/5 as compared with the above embodiment, and the capacitance value can be increased 3 to 5 times.

  FIG. 1B shows a cross section (FIG. 3 II-II) of the periphery of the pixel region of one embodiment of the present invention. A configuration is shown in which a doping region 8 extending in the scanning direction (pixel row direction) of the pixel region is connected to a predetermined potential (Vss). Reference numeral 80 denotes a P-type contact region formed in the same process as the source / drain region of the MOSFET of the peripheral circuit. Impurities having the same polarity are ion-implanted into the doped region 8 formed before the gate electrode is formed after the gate electrode is formed. Formed. The contact region 80 is connected to the wiring 70 through the contact hole 71 and is applied with a constant voltage Vss. The contact region 80 is also shielded from light by a light shielding layer 14 'made of a third metal layer. That is, a light shielding layer 14 ′ separated from the pixel electrode 14 of the outermost pixel of the pixel region is formed in the peripheral region surrounding the entire periphery of the pixel region. This light shielding layer 14 ′ is the same layer as the pixel electrode 14. In order to block light entering from the gap between the outermost pixel electrode 14 and the light shielding layer 14 'in the peripheral region, a first metal layer 12' extends from the light shielding layer 12 in the outermost pixel region. Be placed.

  FIG. 2 shows a cross-sectional view of an embodiment of a CMOS circuit element constituting a peripheral circuit such as a drive circuit outside the pixel region. In FIG. 2, portions denoted by the same reference numerals as those in FIG. 1 indicate metal layers, insulating films, and semiconductor regions formed in the same process.

  In FIG. 2, 4a and 4a 'are N-channel MOSFETs constituting a peripheral circuit (CMOS circuit), gate electrodes of P-channel MOSFETs, and 5a (5b) and 5a' (5b ') are N (source) drain regions. The type doping region, the P type doping region, 5c and 5c ′ are channel regions, respectively. A contact region 80 for supplying a constant potential to the P-type doping region 8 constituting one electrode of the storage capacitor of FIG. 1 is a P-type doping region 5a ′ (5b) that becomes a source (drain) region of the P-channel MOSFET. ') And the same process. Reference numerals 27a and 27c denote sources connected to a power supply voltage (0V, 5V, or 15V) formed of the first metal layer, and 27b denotes a drain electrode formed of the first metal layer. Reference numeral 32a denotes a wiring layer made of a second metal layer, and is used as a wiring for connecting elements constituting the peripheral circuit. 32b is also a power supply wiring layer made of the second metal layer, but also functions as a light shielding layer. The light shielding layer 32b may be connected to any constant potential such as Vc, LC-COM, or a power supply voltage of 0 V, or may be an indefinite potential that is electrically separated from the power supply wiring or the like. 14 ′ is a third metal layer, and in the peripheral circuit portion, this third metal layer is used as a light shielding layer, and light passes through a semiconductor region constituting the peripheral circuit to generate carriers, Prevents the potential in the semiconductor region from becoming unstable. That is, the peripheral circuit is also shielded by the second and third metal layers.

  As described above, the passivation film 17 in the peripheral circuit portion is a two-layer structure in which a silicon nitride film is formed on a silicon nitride film or a silicon oxide film that is superior to the silicon oxide film constituting the passivation film in the pixel region as a protective film. A protective film having a structure may be used. Although not particularly limited, the source / drain regions of the MOSFET constituting the peripheral circuit of this embodiment may be formed by a self-alignment technique. Furthermore, the source / drain regions of any MOSFET may have an LDD (lightly doped drain) structure or a DDD (double doped drain) structure. In consideration of the fact that the pixel switching FET is driven with a large voltage and that it is necessary to prevent light leakage current, it is assumed that the offset (structure having a distance between the gate electrode and the source / drain region) is used. Good.

  4 (a), 4 (b), and 4 (c) show other embodiments of the reflective electrode side substrate for a liquid crystal panel according to the present invention. 4A to 4C, cylinders denoted by the same reference numerals as those in FIGS. 1 and 2 indicate layers and semiconductor regions formed in the same process.

  In the embodiment shown in FIG. 4A, an antireflection film 18 made of, for example, titanium nitride, that is, titanium nitride (TiN) is provided on the back surface of the pixel electrode 14 in the embodiment of FIG. When such an antireflection film 18 is provided, the light shielding effect is further enhanced as compared with the first embodiment of FIG. That is, in the first embodiment, the light shielding layer 12 is provided. Since the light shielding layer 12 is composed of a metal layer having a relatively high reflectance such as aluminum, the reference numeral in FIG. As shown by A, light that has entered through the gap between the pixel electrodes 14 and 14 from an oblique direction is reflected on the surface of the light shielding layer 12 and further reflected on the back surface of the pixel electrode. There is a possibility that light leaks from the opening 12a provided at the portion where the 15 is formed to the MOSFET side and reaches the substrate and a light leakage current flows. However, if the antireflection film 18 is provided, the pixel electrode 14 Light entering from the gap can be absorbed, and light leakage current can be further prevented. The preferred thickness of the antireflection film 18 made of titanium nitride (TiN) is 500 to 1000 angstroms. The antireflection film 18 may be provided not on the back surface of the pixel electrode but on the surface of the light shielding layer 12 or in the middle of the interlayer insulating film.

  In the embodiment shown in FIG. 4B, the antireflection film 18 is provided on the back surface of the pixel electrode 14, and in the embodiment shown in FIG. A V-shaped groove 19 having at least an inclined surface is formed between adjacent pixel electrodes on the surface of the three interlayer insulating film 13. As a result, as shown by reference numeral B, the light incident on the gap between the pixel electrodes 14 from directly above the substrate is reflected in an oblique direction and absorbed by the antireflection film 18 on the back side of the pixel electrode, and is exposed in the gap between the pixel electrodes. It is possible to prevent the light reflected by the surface of the film or the light shielding layer below the film from changing its direction by 180 degrees and emitting it. When such reflected light is emitted, in a normally white mode liquid crystal panel that is configured to reflect incident light and perform white display without applying a voltage to the pixel electrode, the gap between the pixel electrodes Since the light reflected and emitted from the lens looks similar to the light reflected by the pixel electrode to which no voltage is applied, the display image quality may be deteriorated, but the V-groove 19 as shown in FIG. Is formed in the interlayer insulating film 13, since such reflected light can be eliminated, the image quality can be improved.

  In the embodiment shown in FIG. 4C, in the embodiment of FIG. 4A in which the antireflection film 18 is provided on the back surface of the pixel electrode 14, light shielding under the gap between the pixel electrodes 14 and 14 is performed. A V-shaped groove 19 is formed on the surface of the layer 12 along the boundary of each pixel electrode. As a result, the same effect as the embodiment of FIG. 4B described above can be obtained.

  4 (b) and 4 (c) show the groove 19 having a V-shaped cross section, the cross sectional shape is not limited to this, and the inner surface of the groove has at least an inclined surface. Then, the reflected light can be absorbed by the antireflection film by reflecting the incident light on the inclined surface at an angle shifted by 180 ° with respect to the incident direction. Other than this, for example, the groove may be a groove having a slope along the end of one pixel electrode and a vertical surface along the end of the pixel electrode adjacent thereto, or substantially V-shaped. It may be a groove having a slight flat portion on the bottom surface or a plurality of rows of grooves.

  In the configuration of FIG. 4 described above, interlayer insulation composed of the TEOS film (including the SOG film partially remaining after etching) is formed between the reflective electrode 14 and the metal layer as the light shielding layer 12 therebelow. In addition to the film 13, a silicon nitride film may be formed thereunder. Conversely, a silicon nitride film may be formed on the TEOS film 13. By using the structure of the interlayer insulating film 13 having a two-layer structure to which a silicon nitride film is added in this way, it becomes difficult for water or the like to enter and the moisture resistance is improved. This interlayer insulating film having a two-layer structure may be formed on the second metal layers 32a and 32b not only in the pixel region but also in the peripheral region, thereby improving the moisture resistance in the peripheral region. Further, since the refractive index of the silicon nitride film is 1.9 to 2.2 higher than the refractive index 1.4 to 1.6 of the silicon oxide film used for the protective insulating film 17, the protective insulating film 17 has a refractive index from the liquid crystal side. When light is incident, the incident light is reflected by the difference in refractive index at the interface with the silicon nitride film. As a result, the incidence of light on the interlayer film is reduced, so that it is possible to prevent the light from passing through the semiconductor region to generate carriers and the potential in the semiconductor region to become unstable.

  FIG. 5 shows an overall planar layout configuration of a liquid crystal panel substrate (reflection electrode side substrate) to which the above embodiment is applied.

  As shown in FIG. 5, in this embodiment, a light shielding layer 25 for preventing light from entering a peripheral circuit provided at the peripheral edge of the substrate is provided. This light shielding layer is formed of the same layer as the pixel electrode 14. The peripheral circuit is provided around the pixel region 20 in which the pixel electrodes are arranged in a matrix, and the data line driving circuit 21 and the gate line 4 for supplying an image signal corresponding to the image data to the data line 7 in order. A gate line driving circuit 22 for scanning, an input circuit 23 for taking in image data inputted from the outside through the pad region 26, a timing control circuit 24 for controlling these circuits, and the like. The MOSFET formed in the same process as or different from the process MOSFET is used as an active element or a switching element, and a load element such as a resistor or a capacitor is combined therewith.

  In this embodiment, the light shielding layer 25 is composed of a third metal layer formed in the same process as the pixel electrode 14 shown in FIG. A predetermined potential such as a potential is applied. By applying a predetermined potential to the light shielding layer 25, reflection can be reduced as compared with the case of floating or other potential. Further, the light shielding layer 25 can be floated without being connected to the power supply wiring. In this way, since no potential is applied to the liquid crystal layer by the light shielding layer 25, erroneous display is prevented in the peripheral region.

  Reference numeral 26 denotes a pad region in which pads or terminals used for supplying a power supply voltage are formed. The position where the sealing material is provided is set so that the pad region 26 for inputting a signal from the outside comes outside the sealing material 36.

  FIG. 6 shows a sectional configuration of a reflective liquid crystal panel to which the liquid crystal panel substrate 31 is applied. As shown in FIG. 6, the liquid crystal panel substrate 31 has a support substrate 32 made of glass or ceramics adhered to the back surface thereof with an adhesive. At the same time, an incident-side glass substrate 35 having a counter electrode (also referred to as a common electrode) 33 made of a transparent conductive film (ITO) to which an LC common potential is applied is disposed on the surface side at an appropriate interval. A well-known TN (Twisted Nematic) type liquid crystal or an SH (Super Homeotropic) type liquid crystal 37 in which liquid crystal molecules are substantially vertically aligned in a state in which no voltage is applied is filled in a gap whose periphery is sealed with a sealing material 36. The liquid crystal panel 30 is configured.

  The light shielding layer 25 on the peripheral circuit is configured to face the counter electrode 33 with the liquid crystal 37 interposed therebetween. If the LC common potential is applied to the light shielding layer 25, the LC common potential is applied to the counter electrode 33, so that no DC voltage is applied to the liquid crystal interposed therebetween. Therefore, the liquid crystal molecules always remain twisted by about 90 ° in the case of the TN liquid crystal, and the liquid crystal molecules are always kept in the vertically aligned state in the case of the SH liquid crystal.

  In this embodiment, the liquid crystal panel substrate 31 made of a semiconductor substrate has a significantly increased strength because a support substrate 32 made of glass, ceramic or the like is bonded to the back surface thereof with an adhesive. As a result, when the support substrate 32 is bonded to the liquid crystal panel substrate 31 and then bonded to the counter substrate, there is an advantage that the gap of the liquid crystal layer becomes uniform over the entire panel.

(Description of LCD panel substrate using insulating substrate)
In the above description, the configuration of a liquid crystal panel substrate using a semiconductor substrate and the liquid crystal panel using the same have been described. The structure of a reflective liquid crystal panel substrate using an insulating substrate such as glass will be described below. To do.

  FIG. 10 is a cross-sectional view showing a configuration of a pixel of a reflective liquid crystal panel substrate. This figure shows a cross-sectional view along line II in the plan layout diagram of FIG. In this embodiment, a TFT is used as a pixel switching transistor. In FIG. 10, portions denoted by the same reference numerals as those in FIGS. 1 and 2 indicate layers and semiconductor regions having the same functions as those in these drawings. Reference numeral 1 denotes a quartz or non-alkali glass substrate, and a monocrystalline, polycrystalline, or amorphous silicon film (formation layer of 5a, 5b, 5c, 8) is formed on the insulating substrate. Insulating films 4b and 9b having a two-layer structure of a silicon oxide film formed by thermal oxidation and silicon oxide or silicon nitride deposited by a CVD method are formed. Before forming the upper silicon oxide or silicon nitride film on the insulating film 4b, the regions 5a, 5b, and 8 of the silicon film are doped with N-type impurities, so that the source region 5a, the drain region 5b, and the holding region of the TFT are retained. A capacitive electrode region 8 is formed. Further, on the insulating film 4b, a wiring layer such as polysilicon or metal silicide, which becomes the gate electrode 4a of the TFT and the other electrode 9a of the storage capacitor, is formed. As described above, the TFT including the gate electrode 4a, the gate insulating film 4b, the channel 5c, the source 5a, and the drain 5b, and the storage capacitor including the electrodes 8, 9a and the insulating film 9b are formed.

  A first interlayer insulating film 6 made of silicon nitride or silicon oxide is formed on the wiring layers 4a and 9a, and a source connected to the source region 5a through a contact hole formed in the insulating film 6 is formed. The electrode 7a is formed of a first metal layer made of an aluminum layer. An interlayer insulating film 11 and a light shielding layer 12 are formed on the first metal layer as in FIG. A second interlayer insulating film 13 formed of a silicon oxide film or a silicon nitride film or a two-layer structure of a silicon oxide film and a silicon nitride film is further formed on the light shielding layer 12. The second interlayer insulating film 13 is planarized by a CMP method, and a pixel electrode serving as a reflective electrode made of aluminum is formed on each pixel. The electrode region 8 of the silicon film and the pixel electrode 14 are electrically connected through the contact hole 16. This connection is made by embedding and forming a connection plug 15 made of a refractory metal such as tungsten, as in FIG. The light shielding layer 12 is also formed at a portion corresponding to the cross-sectional view of FIG. 1B, and light entering from the gap between the pixel electrode 14 and the light shielding layer 14 ′ that shields the surrounding area from the same layer. A light shielding layer 12 ′ that shields light is disposed as a second metal layer.

  As described above, since the reflective electrode is formed above the TFT and the storage capacitor formed on the insulating substrate, the pixel electrode area is widened, and the storage capacitor is located under the reflective electrode as in the plan layout diagram of FIG. Therefore, even in a high-definition (small pixel) panel, not only a high aperture ratio (reflectance) can be obtained, but also the applied voltage can be sufficiently held in each pixel. Drive stabilizes.

  As in the previous embodiments, a passivation film 17 made of a silicon oxide film is formed on the reflective electrode 14. The overall configuration of the liquid crystal panel substrate and the configuration of the liquid crystal panel are the same as those shown in FIGS. Accordingly, peripheral circuits such as a drive circuit are also configured with TFTs as transistor elements. In the peripheral region including the peripheral circuit portion, as in FIG. 2, the second metal layers 32a and 32b serve as connection wirings between the elements above the CMOS TFTs and as light shielding layers that extend / separate them. Has been.

  If light incidence from below the substrate is assumed, a light shielding layer may be further disposed under the silicon films 5a, 5b, and 8. In the figure, the gate electrode is a top gate type in which the gate electrode is located above the channel. However, the gate electrode is formed first, and the bottom gate type in which the silicon film serving as the channel is disposed on the gate insulating film. Good. Furthermore, moisture resistance can be improved by forming the peripheral circuit region into a silicon nitride film or a two-layer structure of a silicon oxide film and a silicon nitride film.

(Description of an electronic apparatus using the reflective liquid crystal panel of the present invention)
FIG. 8 is an example of an electronic apparatus using the liquid crystal panel of the present invention, and is a schematic configuration in plan view of the main part of a projector (projection display device) using the reflective liquid crystal panel of the present invention as a light valve. FIG. FIG. 8 shows a polarization illumination device 100 schematically constituted by a light source unit 110, an integrator lens 120, and a polarization conversion element 130 arranged through the center of the optical element 130, and an S polarization bundle emitted from the polarization illumination device 100 as S. Of the light reflected from the S-polarized light reflecting surface 201 of the polarizing beam splitter 200 and the polarizing beam splitter 200 that is reflected by the polarizing beam reflecting surface 201, the dichroic mirror 412 that separates the blue light (B) component, and the separated blue light. (B) is a reflective liquid crystal light valve 300B that modulates blue light, a dichroic mirror 413 that reflects and separates red light (R) component from the luminous flux after blue light is separated, and separated red light ( The remaining green light (G) that passes through the reflective liquid crystal light valve 300R that modulates R) and the dichroic mirror 413 The light modulated by the reflective liquid crystal light valve 300G to be modulated and the three reflective liquid crystal light valves 300R, 300G, and 300B are combined by the dichroic mirrors 412 and 413 and the polarization beam splitter 200, and the combined light is combined with the screen 600. The projection optical system 500 includes a projection lens for projection. The liquid crystal panels described above are used for the three reflective liquid crystal light valves 300R, 300G, and 300B, respectively.

  The random polarization bundle emitted from the light source unit 110 is divided into a plurality of intermediate light beams by the integrator lens 120, and then the polarization direction is substantially aligned by the polarization conversion element 130 having the second integrator lens on the light incident side. After being converted into a kind of polarization bundle (S polarization bundle), the polarization beam splitter 200 is reached. The S-polarized light flux emitted from the polarization conversion element 130 is reflected by the S-polarized light flux reflecting surface 201 of the polarization beam splitter 200, and among the reflected light flux, the blue light (B) light flux is reflected by the dichroic mirror 412. Reflected by the layer and modulated by the reflective liquid crystal light valve 300B. Of the light beams transmitted through the blue light reflecting layer of the dichroic mirror 412, the red light (R) light beam is reflected by the red light reflecting layer of the dichroic mirror 413 and modulated by the reflective liquid crystal light valve 300R.

  On the other hand, the luminous flux of green light (G) transmitted through the red light reflection layer of the dichroic mirror 413 is modulated by the reflective liquid crystal light valve 300G. In this way, the reflective liquid crystal panels that are modulated reflective liquid crystal light valves 300R, 300G, and 300B by the reflective liquid crystal light valves 300R, 300, and 300B are TN liquid crystals (the major axis of the liquid crystal molecules is applied with no voltage applied). Sometimes, a liquid crystal aligned in parallel with the panel substrate) or an SH type liquid crystal (liquid crystal in which the major axis of the liquid crystal molecules is aligned substantially perpendicular to the panel substrate when no voltage is applied) is employed.

  When a TN type liquid crystal is adopted, in a pixel (OFF pixel) in which the voltage applied to the liquid crystal layer sandwiched between the reflective electrode of the pixel and the common electrode of the opposing substrate is lower than the threshold voltage of the liquid crystal The incident color light is elliptically polarized by the liquid crystal layer, reflected by the reflective electrode, and reflected through the liquid crystal layer as light in a state close to elliptically polarized light with a large amount of polarization axis component shifted by approximately 90 degrees from the polarization axis of the incident color light. -It is emitted. On the other hand, in a pixel (ON pixel) to which a voltage is applied to the liquid crystal layer, the incident color light reaches the reflection electrode, is reflected, and is reflected and emitted with the same polarization axis as that at the time of incidence. Since the alignment angle of the liquid crystal molecules of the TN liquid crystal changes according to the voltage applied to the irregular electrode, the angle of the polarization axis of the reflected light with respect to the incident light depends on the voltage applied to the reflective electrode via the pixel transistor. Variable.

  In addition, when the SH type liquid crystal is adopted, in a pixel (OFF pixel) in which the applied voltage of the liquid product layer is equal to or lower than the threshold voltage of the liquid crystal, the incident color light reaches the reflection electrode as it is, and is reflected. Is reflected and emitted with the same polarization axis. On the other hand, in a pixel (ON pixel) in which a voltage is applied to the liquid crystal layer, the incident color light is elliptically polarized in the liquid crystal layer, reflected by the reflective electrode, and the polarization axis with respect to the polarization axis of the incident light via the liquid crystal layer. Is reflected and emitted as elliptically polarized light with a large polarization axis component shifted by approximately 90 degrees. As in the case of the TN type liquid crystal, the alignment angle of the liquid crystal molecules of the SH type liquid crystal changes according to the voltage applied to the reflection electrode, and therefore the angle of the polarization axis of the reflected light with respect to the incident light passes through the pixel transistor. The voltage is varied according to the voltage applied to the reflective electrode.

  Of the color light reflected from the pixels of these liquid crystal panels, the S-polarized component does not pass through the polarizing beam splitter 200 that reflects S-polarized light, while the P-polarized component passes through. An image is formed by the light transmitted through the polarization beam splitter 200. Therefore, when a TN type liquid crystal is used for the liquid crystal panel, the projected image is normally white display because the reflected light of the OFF pixel reaches the projection optical system 500 and the reflected light of the ON pixel does not reach the lens. Is used, the reflected light of the OFF pixel does not reach the projection optical system, and the reflected light of the ON pixel reaches the projection optical system 500, so that normally black display is achieved.

  The reflective liquid crystal panel can be formed with a larger number of pixels and the panel size can be reduced because pixels are formed using semiconductor technology compared to an active matrix liquid crystal panel in which a TFT array is formed on a glass substrate. A high-definition image can be projected and the projector can be miniaturized.

  As described with reference to FIG. 6, the peripheral circuit portion of the liquid crystal panel is covered with a light shielding layer, and has the same potential (for example, LC common potential, but not the LC common potential) together with the counter electrode formed at the position facing the counter substrate. In this case, since the potential is different from that of the counter electrode of the pixel portion, in this case, a peripheral counter electrode separated from the counter electrode of the pixel portion is applied. Applied, the liquid crystal becomes the same as the OFF state. Therefore, in the TN liquid crystal panel, the entire periphery of the image area can be displayed in white according to the normally white display, and in the SH liquid crystal panel, the periphery of the image area is completely black in accordance with the normally black display. Can be displayed.

  According to the above embodiment, the voltage applied to the pixel electrodes of the reflective liquid crystal panels 300R, 300G, and 300B is sufficiently held, and a clear image is obtained because the reflectance of the pixel electrodes is very high.

  FIG. 9 is an external view showing an example of an electronic apparatus using the reflective liquid crystal panel of the present invention. These electronic devices are not used as light valves used with polarizing beam splitters, but as direct-view reflective liquid crystal panels, so that the reflective electrode does not need to be a perfect mirror surface and widens the viewing angle. However, it is desirable to provide an appropriate unevenness, but the other components are basically the same as those of the light valve.

  FIG. 9A is a perspective view showing a mobile phone. Reference numeral 1000 denotes a mobile phone main body, and 1001 of the main body is a liquid crystal display unit using the reflective liquid crystal panel of the present invention.

  FIG. 9B shows a wristwatch type electronic device. 1100 is a perspective view showing a watch body. Reference numeral 1101 denotes a liquid crystal display unit using the reflective liquid crystal panel of the present invention. Since this liquid crystal panel has high-definition pixels as compared with a conventional clock display unit, it can also display a television image and can realize a watch-type television.

  FIG. 9C illustrates a portable information processing apparatus such as a word processor or a personal computer. Reference numeral 1200 denotes an information processing apparatus, 1202 denotes an input unit such as a keyboard, 1206 denotes a display unit using the reflective liquid crystal panel of the present invention, and 1204 denotes an information processing apparatus main body. Since each electronic device is an electronic device driven by a battery, the life of the battery can be extended by using a reflective liquid crystal panel having no light source lamp. Further, since the peripheral circuit can be built in the panel substrate as in the present invention, the number of parts is greatly reduced, and the weight and size can be further reduced.

  In the above embodiments, the TN type and homeotropic alignment SH type have been described as the liquid crystal of the liquid crystal panel. However, it goes without saying that the liquid crystal panel can be replaced with other liquid crystals.

  As described above, according to the present invention, the pixel electrode and the terminal electrode are disposed between the pixel electrode as the reflective electrode and the conductive layer constituting the terminal electrode of the switching element that applies a voltage to the pixel electrode. Since the light shielding layer having the opening in the pixel region is provided only in the contact hole forming portion for connection, the amount of light leaking from the incident side to the driving element side can be almost zero, and the semiconductor layer or semiconductor There is an effect that the light leakage current flowing through the substrate can be greatly reduced.

  In a reflective liquid crystal panel in which pixel electrodes are arranged in a matrix on the same substrate and a peripheral circuit is provided outside the pixel region, a metal layer constituting the reflective electrode in the pixel region is included in the peripheral circuit. Since the light-shielding layer composed of the same layer is provided, the light leakage current can be reduced by reducing the light leakage amount of the pixel region and the peripheral circuit without increasing the number of process steps. There is.

  Furthermore, in a reflective liquid crystal panel in which pixel electrodes are arranged in a matrix on the same substrate and a peripheral circuit is formed outside the pixel region, a wiring layer or a light shield is formed below the pixel electrode layer by the peripheral circuit. Since the light shielding layer of the pixel region is formed using the layer used as the layer, there is an effect that the light shielding layer can be formed without increasing the number of process steps.

  Further, since an antireflection film is provided below the pixel electrode, even when the light shielding layer is formed of a metal layer having a relatively high reflectance, light reflected from the surface of the light shielding layer can be absorbed. The semiconductor layer or the semiconductor substrate is formed by light leaking downward from an opening provided in a conductor forming portion that connects the pixel electrode and the switching element by repeatedly reflecting between the surface of the light shielding layer and the back surface of the pixel electrode. It is possible to prevent the light leakage current from flowing.

  In addition, an antireflection film is provided on the lower side of the pixel electrode, and a groove having at least a slope is formed on the surface of the insulating film exposed in the gap between the pixel electrode and the pixel electrode in the pixel region or on the surface of the light shielding layer below the pixel electrode. Since it is formed between the electrodes, light incident from the gap between the pixel electrodes is reflected obliquely and absorbed by the antireflection film on the back side of the pixel electrode, and the insulating film exposed in the gap between the pixel electrodes There is an effect that it is possible to improve the display image quality by preventing the light reflected by the light shielding layer on the surface or below the light from changing its direction by 180 degrees and emitting it.

(A) is sectional drawing which shows one Example of the pixel area | region in the reflective electrode side board | substrate of the reflective liquid crystal panel to which this invention is applied, (b) is a pixel in the reflective electrode side board | substrate of the reflective liquid crystal panel to which this invention is applied. It is sectional drawing of the boundary part of an area | region and a periphery area | region. It is sectional drawing which shows an example of the peripheral circuit part in the reflective electrode side board | substrate of the reflection type liquid crystal panel to which this invention is applied. It is a plane layout figure of one Example of the pixel area | region in the reflective electrode side board | substrate of the reflection type liquid crystal panel to which this invention is applied. (A) (b) (c) is sectional drawing which shows the other Example of the gap | interval structure of the pixel electrode in the reflective electrode side board | substrate of the reflection type liquid crystal panel to which this invention is applied. It is a top view which shows the circuit layout structural example of the reflective electrode side board | substrate in the reflective liquid crystal panel of an Example. It is sectional drawing which shows an example of the reflective liquid crystal panel to which the board | substrate for liquid crystal panels of an Example is applied. It is a wave form diagram which shows an example of an applied voltage waveform and a data line applied voltage waveform to the gate of the switching element of the pixel of the reflection type liquid crystal panel to which this invention is applied. It is a schematic block diagram of an example of the projection type display apparatus which applied the reflective liquid crystal panel of the Example as a light valve. (A), (b), (c) is an external view which shows the example of the electronic device using the reflection type liquid crystal panel of this invention, respectively. It is sectional drawing which shows the other Example of the reflective electrode side board | substrate to which this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Well area | region, 3 ... Field oxide film, 4 ... Gate line, 6, 11, 13 ... Interlayer insulation film, 6a, 6b, 6c, 16, 71 ... Contact hole, 7 ... Data line, 10 Auxiliary coupling wirings 12, 25: Light shielding layer, 12a: Opening, 14: Pixel electrode, 15: Connection plug, 17 ... Protective insulating film, 18 ... Antireflection film, 20 ... Pixel region, 21 ... Data line driving circuit DESCRIPTION OF SYMBOLS 22 ... Gate line drive circuit 23 ... Input circuit 24 ... Timing control circuit 26 ... Pad area | region 30 ... Liquid crystal panel 31 ... Liquid crystal panel board | substrate 32 ... Support substrate 80 ... Contact area | region 100 ... Polarized illumination apparatus DESCRIPTION OF SYMBOLS 110 ... Light source part 120 ... Integrator lens 130 ... Polarization conversion element 200 ... Polarization beam splitter 201 ... S polarization bundle reflecting surface 412, 413 ... Dichroic mirror 500 ... projection optical system, 600 ... screen, Vc ... central potential, Vd ... image signal voltage, Vss ... voltage.

Claims (6)

In a liquid crystal panel substrate in which unit pixels having pixel electrodes to be reflective electrodes and switching elements provided corresponding to the pixel electrodes are arranged in a matrix on the substrate,
A first light-shielding layer that covers a region between adjacent pixel electrodes is provided between the pixel electrode and the switching element in a pixel region in which the unit pixels are arranged in a matrix .
An interlayer insulating film is disposed between the pixel electrode and the first light shielding layer,
A silicon nitride film is formed on the pixel electrode side of the interlayer insulating film, and an antireflection film is formed between the silicon nitride film and the pixel electrode ,
A second light shielding layer formed simultaneously with the pixel electrode from the same metal layer and a third light shielding layer formed simultaneously with the first light shielding layer from the same metal layer in a peripheral region disposed outside the pixel region. And having a layer
The substrate for a liquid crystal panel , wherein the interlayer insulating film is disposed between the second light shielding layer and the third light shielding layer . In a liquid crystal panel substrate in which unit pixels having pixel electrodes to be reflective electrodes and switching elements provided corresponding to the pixel electrodes are arranged in a matrix on the substrate,
A first light-shielding layer covering a region between adjacent pixel electrodes is provided between the pixel electrode and the switching element;
An interlayer insulating film is disposed between the pixel electrode and the first light shielding layer,
A silicon nitride film is formed on the pixel electrode side of the interlayer insulating film, and an antireflection film is formed between the silicon nitride film and the pixel electrode ,
The substrate for a liquid crystal panel, wherein the interlayer insulating film or the first light shielding layer is formed with a groove having at least a slope in a region between the adjacent pixel electrodes . In a liquid crystal panel substrate in which unit pixels having pixel electrodes to be reflective electrodes and switching elements provided corresponding to the pixel electrodes are arranged in a matrix on the substrate,
A first light-shielding layer covering a region between adjacent pixel electrodes is provided between the pixel electrode and the switching element;
An interlayer insulating film is disposed between the pixel electrode and the first light shielding layer,
A silicon nitride film is formed on the pixel electrode side of the interlayer insulating film, and an antireflection film is formed between the silicon nitride film and the pixel electrode ,
The interlayer insulating film has a TEOS film, and is a liquid crystal panel substrate. Liquid crystal panel characterized in that it is constituted by sandwiching a liquid crystal between the liquid crystal panel substrate according to any one of claims 1 to 3 and the substrate opposite thereto. An electronic apparatus comprising the liquid crystal panel according to claim 4 as a display unit. 5. A projection display device comprising: a light source; the liquid crystal panel according to claim 4 that modulates light from the light source; and projection optical means that condenses and projects the light modulated by the liquid crystal panel. .

Images