JPH10293323A - Liquid crystal panel, substrate therefor, electronic equipment and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need of wiring for feeding controlled potential to one of electrodes of retention volume by electrically connecting the conductive layer of a semiconductor substrate to a feed layer for giving the controlled potential outside a picture element zone. SOLUTION: A source zone 5a and a drain zone 5b made of a high impurity introduction layer are formed on substrate surface at both sides of a gate electrode 4a, thereby forming MOSFET. Also, a contact zone 7 of a P-type impurity introduction layer of high concentration is formed on the substrate surface in such a state as corresponding to a part of a conductive layer 6, and one and of the conductive layer 6 is connected to the contact zone 7 at an opening 3a formed on an insulation film 3' so as to correspond to the contact zone 7. A feed layer 19 to apply controlled potential outside a picture element zone and a P-type contact zone 17 of high impurity concentration for electrically connecting the feed layer 19 are formed on a semiconductor substrate 1. As a result, controlled potential for giving inverse bias to a P-N junction is applied, and substrate potential given from the feed layer 19 is applied to the conductive layer 6, thereby fixing the potential.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel and, more particularly, to a reflection type liquid crystal panel, and more particularly to an insulated gate field effect transistor (hereinafter referred to as a MOS) formed on a semiconductor substrate.
The present invention relates to a technique suitable for use in an active matrix type liquid crystal panel in which pixel electrodes are switched by an FET.

[0002]

2. Description of the Related Art Conventionally, as a transmission type active matrix liquid crystal panel used for a light valve of a projection type display device, a liquid crystal panel having a structure in which a TFT array using amorphous silicon or polysilicon is formed on a glass substrate has been commercialized. Have been.

[0003]

Since the active matrix liquid crystal panel using the above-mentioned TFT has a relatively large device size, for example, in a projection display device such as a projector in which this is incorporated as a light valve, the whole device is used. However, there is a problem that the size becomes large.
Further, in the case of a transmissive liquid crystal panel, the area of the TFT provided in each pixel does not become the transmissive area of the pixel that transmits light, so that the aperture ratio becomes smaller as the resolution of the panel increases to XGA and SXGA. Deficiency.

[0004] Therefore, as a liquid crystal panel smaller in size than a transmissive active matrix liquid crystal panel, a reflection type active matrix liquid crystal panel in which a pixel electrode serving as a reflection electrode is switched by a MOSFET array formed on a semiconductor substrate is used. Proposed.

However, in a liquid crystal panel using a semiconductor as a substrate, the size of each pixel also decreases as the panel resolution increases as the device size decreases. Therefore, only the pixel electrodes are required to hold the voltage required for driving the liquid crystal. However, there is a disadvantage that a sufficient capacity (about 100 fF is required) cannot be obtained. Thus, the present inventors have studied a method of forming a storage capacitor having a gate insulating film as a dielectric in each pixel.

However, it is desirable that one electrode of the storage capacitor is fixed at a constant potential. A wiring for supplying such a constant potential to each storage capacitor (hereinafter referred to as a capacitance line).
It has been found that it is extremely difficult to secure the layout and contact hole formation position.

FIGS. 10 and 11 show a structure of a storage capacitor in a reflection type liquid crystal panel using a semiconductor as a substrate, which was examined by the present inventors prior to the present invention, and a method for supplying a constant potential to one electrode of the storage capacitor. An example of a method of laying out the capacitance lines of FIG. FIG. 11 shows AA ′ and B− in FIG.
It is sectional drawing which showed the discontinuous cross section of B 'continuously. FIG.
In 0, 4a is a gate electrode of a switching MOSFET, 9 is a data line for supplying a signal to be applied to a pixel to the switching MOSFET, 12 is a reflective electrode made of aluminum or the like, and 6 is a conductive electrode serving as one electrode of a storage capacitor. Layer.

In the example shown in FIG. 10, a diffusion layer 5b as a drain region to which the reflection electrode 12 is connected is formed widely to serve as the other electrode of the storage capacitor. The conductive layer 6 as one electrode is formed of, for example, the same polysilicon layer as the gate electrode.
As a method for applying a constant potential to the conductive layer 6 as one electrode of the storage capacitor, as shown in FIG. 11, the storage of adjacent pixels by the capacitor line 16 made of the same polysilicon layer as the conductive layer 6 is performed. The capacitor line is connected to a conductive layer as an electrode of a capacitor, and the capacitor line 16 is connected to a wiring for supplying a constant potential such as a ground potential outside the pixel region.

However, in the methods shown in FIGS. 10 and 11, since the capacitance lines are formed between the conductive layers as the storage capacitance electrodes of the respective pixels, the irregularities on the surface of the insulating film become large, and the reflection occurs. There is a disadvantage that it is difficult to flatten the electrodes. In addition, since the capacitance line 16 and the data line 9 intersect, the parasitic capacitance of the data line increases, and noise enters the storage capacitance via the coupling capacitance between the capacitance line 16 and the data line 9 to stabilize the potential. There is a problem that it will not be.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique for improving the yield by eliminating the need for wiring for supplying a constant potential to one electrode of a storage capacitor in a reflective liquid crystal panel using a semiconductor as a substrate. It is in.

Another object of the present invention is to provide a technique for easily flattening a reflection electrode in a reflection type liquid crystal panel using a semiconductor as a substrate.

Another object of the present invention is to provide a technique capable of stabilizing a constant voltage applied to a storage capacitor.

Another object of the present invention is to provide a technique capable of obtaining a required storage capacity without increasing the number of process steps.

[0014]

In order to achieve the above object, the present invention provides an element (MOSF) for switching a pixel electrode on a surface of a semiconductor substrate below a pixel electrode serving as a reflective electrode.
A semiconductor region having a relatively high impurity concentration to be an active region (drain region) of ET) is extended and formed as one electrode of a storage capacitor, and the other electrode of the storage capacitor is formed above the semiconductor region via an insulating film. A conductive layer formed on the surface of the semiconductor substrate and electrically connected to the semiconductor substrate through a high-concentration semiconductor region of the same conductivity type formed on the surface of the semiconductor substrate. Outside, was electrically connected to a power supply layer for applying a potential.

According to the above-mentioned means, since the substrate potential is applied to one electrode of the storage capacitor, a capacitor line for supplying a potential to one electrode of the storage capacitor becomes unnecessary.
The structure of the pixel is simplified, the yield is improved, and the irregularities on the surface of the insulating film are reduced, and the flattening of the reflective electrode is facilitated. Further, it is not necessary to form a capacitance line that intersects with a data line that supplies a signal applied to each pixel electrode, so that the parasitic capacitance of the data line can be reduced, and the noise to the storage capacitor is reduced to reduce the potential. Can be stabilized.

The insulating film constituting the dielectric of the storage capacitor is an insulating film formed simultaneously with the gate insulating film provided between the gate electrode of the MOSFET and the channel region, and one electrode of the storage capacitor. It is preferable to use a conductive layer formed simultaneously with the gate electrode of the MOSFET as the conductive layer.

Further, the switching element may be a complementary transistor in which a P-channel transistor and an N-channel transistor are formed in one pixel.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 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 2 show a cross-sectional view and a planar layout of one pixel portion of the pixels arranged in a matrix. FIG. 1 shows a cross section taken along line II in FIG.

In FIG. 1, reference numeral 1 denotes a P-type semiconductor substrate such as single-crystal silicon (may be a P-type well), and 2 denotes a field oxide film (so-called LOCOS) formed on the surface of the semiconductor substrate 1 for element isolation. It is. This field oxide film 2 is formed to a thickness of about 5000 to 7000 Å by selective thermal oxidation.

An opening is formed in the field oxide film 2 for each pixel, and a gate oxide film (insulating film) 3 is formed on the substrate surface inside the opening.
A gate electrode 4a made of polysilicon or metal silicide is formed thereon, and source and drain regions 5a and 5b made of a high impurity concentration N-type impurity-doped layer are formed on the substrate surface on both sides of the gate electrode 4a. , MO
An SFET is configured. In this embodiment, the drain region 5b of the source and drain regions 5a and 5b is extended inside the pixel region along the substrate surface, and is formed simultaneously with the gate insulating film 3 above the extended portion 5b '. A conductive layer 6 serving as one electrode of the storage capacitor is formed via the insulating film 3 '.

The conductive layer 6 is formed of, but not limited to, the same polysilicon or metal silicide as the gate electrode 4a. The above gate electrode 4
a is one direction of the substrate (pixel row direction) as shown in FIG.
Is formed so as to protrude from the scanning line 4 disposed in the first position.

A contact region 7 made of a high-concentration P-type impurity-doped layer for achieving ohmic contact is formed on the surface of the substrate corresponding to a part of the conductive layer 6, and one end of the conductive layer 6 has one end. Corresponding to this contact region 7, contact region 7 is formed in opening 3a formed in insulating film 3 '.
It is connected to the. On the semiconductor substrate 1, a power supply layer 19 for applying a constant potential (ground potential in the case of a P-type substrate / P-type well) outside the pixel region and a high impurity concentration conductive layer to which the power supply layer 19 is electrically connected. A P-type contact region 17 is provided, a constant potential for applying a reverse bias to the PN junction is applied, and a substrate potential applied from the power supply layer 19 through the contact region 7 to the conductive layer 6 is provided. Is applied, and the potential is fixed.
The power supply layer 19 is formed of the same aluminum layer as the data line 9.

The insulating films 3 and 3 'are formed on the surface of the semiconductor substrate inside the openings by thermal oxidation to a thickness of 400 to 800 angstroms. The above gate electrode 4
a and the conductive layer 6 are made of a polysilicon layer of 1000 to 20
00 angstrom thick, and M
a silicide layer of a refractory metal such as
The structure is such that it is formed to a thickness of about 00 to 3000 angstroms. The source region 5a is formed in a self-aligned manner by ion-implanting an N-type impurity into the substrate surface using the gate electrode 4a as a mask.

The N-type drain region 5b and P
In this embodiment, the mold contact region 7 is formed by an ion implantation method before forming a gate electrode by a dedicated ion implantation and a doping process by a heat treatment. The preferred impurity concentration of the source and drain regions 5a and 5b is 1
× 10 ²⁰ / cm ³ , and a preferred impurity concentration of the P-type contact region 7 is 1 × 10 ¹⁸ to 10 ²⁰ / cm ³ . The N-type drain region 5b and the P-type contact region 7 may be formed at the same time as the impurity introduction layers serving as the source and drain regions of a MOSFET which is formed outside the pixel region and constitutes a peripheral circuit described later. good.

A first interlayer insulating film 8 is formed from gate electrode 4a and conductive layer 6 to field oxide film 2, and a data line 9 made of a metal layer mainly composed of aluminum is formed on insulating film 8. As shown in FIG. 2, the data line 9 is formed in a direction intersecting the scanning line 4, and the data line 9 is electrically connected to the source region 5 a through a contact hole 10 formed in the insulating film 8.

The insulating film 8 is, for example, an HTO film (high-temperature C
A silicon oxide film formed by a VD method is deposited on the order of 1000 angstroms, and a BPSG film (a silicate glass film containing boron and phosphorus) is 8000 to 1
It is formed by depositing a thickness such as 0000 angstroms. The metal layer constituting the data line 9 has, for example, a four-layer structure of Ti / TiN / Al / TiN from the bottom. In each layer, the lower layer is composed of 100 to 600 angstroms of Ti, about 1000 angstroms of TiN, 4000 to 10000 angstroms of Al, and TiN of the upper layer.
Has a thickness such as 300 to 600 angstroms.

A second interlayer insulating film 11 is formed from the data line 7 to above the interlayer insulating film 8. This second
The 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 (tetraethylorthosilicate) as a material for about 3000 to 6000 angstroms, and then forming an SOG film (spin-on). An on-glass film is deposited, it is etched back and then a second T
It is formed by depositing an EOS film to a thickness of about 2000 to 5000 angstroms.

In this embodiment, as shown in FIG. 2, a pixel electrode 12 as a rectangular reflective electrode corresponding to one pixel is formed on the second interlayer insulating film 11 as shown in FIG. . A contact hole 13 penetrating the second interlayer insulating film 11, the first interlayer insulating film 8, and the gate insulating film 2 is provided.
At 3, the pixel electrode 12 is electrically connected to the drain region 5b. The pixel electrode 12 is not particularly limited. For example, an aluminum layer is formed to a thickness of 300 to 5000 angstroms by a low-temperature sputtering method, and is formed into a square shape with one side of about 15 to 20 μm by patterning. In addition, the pixel electrode 1
2, a passivation film is formed, and an alignment film is entirely formed thereon, followed by rubbing.

FIG. 2 is a plan layout of the liquid crystal panel substrate on the reflection side shown in FIG. As shown in the figure, in this embodiment, a conductive layer 6 which is one electrode of the storage capacitor is provided along the gate line 4 and in the vicinity thereof. However, the conductive layer 6 and the drain extension 5b 'as the other electrode of the storage capacitor provided on the substrate surface facing the conductive layer 6 are formed of a reflective electrode excluding the portions where the MOSFET gate electrode 4a and the contact holes 10 and 13 are formed. 12
Can be formed all over the lower part.

In this embodiment, since it is not necessary to provide a capacitance line for connecting the conductive layer 6 which is one electrode of the storage capacitor of each pixel, the structure of the pixel is simplified, the yield is improved, and the insulating film is formed. The unevenness on the surface of the surface 11 becomes small, and it becomes easy to form a flat reflective electrode 12. Further, since there is no capacitance line intersecting with the data line, unnecessary parasitic capacitance is attached to the data line, so that the load on the driver is increased and noise is hardly added to the storage capacitance via the coupling capacitance. Further, the insulating film 3 'constituting the dielectric of the storage capacitor is an insulating film formed simultaneously with the gate insulating film 3 provided between the gate electrode of the MOSFET and the channel region, and one electrode of the storage capacitor. Conductive layer 6 constituting
Uses a conductive layer formed simultaneously with the gate electrode 4a of the MOSFET, so that a storage capacitor can be formed without increasing the number of process steps, and the process can be simplified. .

The contact hole 13 may be filled with a columnar connection plug made of a refractory metal such as tungsten, and the pixel electrode 12 may be connected to the drain region 5b via the connection plug. good. In this case, the pixel electrode 12 is not particularly limited, but after tungsten or the like forming a connection plug is deposited by a CVD method, the tungsten and the second interlayer insulating film 11 are subjected to CMP.
(Chemical mechanical polishing) method and then flattening, and then forming by applying an aluminum layer,
After the interlayer insulating film is planarized, the contact hole 13 is opened, and after filling it with tungsten, an aluminum layer forming the pixel electrode 12 may be formed.

In the above embodiment, the case where the pixel switching MOSFET is an N-channel type and the semiconductor region (5b ') serving as one electrode of the storage capacitor is an N-type impurity introduction layer has been described. 1 is an N-type substrate or N-type well, and a MOSFET for pixel switching
May be a P-channel type, and the semiconductor region (5b ′) serving as one electrode of the storage capacitor may be a P-type impurity introduction layer. In this case, the contact region 7 becomes an N-type impurity introduction layer, and the potential supplied thereto becomes a high power supply potential.

In the above embodiment, the pixel switching MOSFET is formed on the surface of the semiconductor substrate. However, a well region of a conductivity type different from that of the substrate is formed on the surface of the semiconductor substrate. The present invention can also be applied to a device in which a pixel switching MOSFET is formed. In this case, the well region of the pixel region is preferably a well region separated from the well region of the MOSFET forming the peripheral circuit.

Further, a MOSFE for pixel switching
Since a large voltage such as 15 V is applied to the gate electrode 4 a of T, the peripheral circuit is driven by a small voltage such as 5 V. Therefore, the gate insulating film of the FET constituting the peripheral circuit is subjected to pixel switching. A technology is considered that is formed thinner than the gate insulating film of the FET for use to improve the characteristics of the FET and increase the operation speed of the peripheral circuit. When such a technique is applied, the thickness of the gate insulating film of the FET constituting the peripheral circuit is reduced to about one third to one fifth of the thickness of the gate insulating film of the pixel switching FET from the breakdown voltage of the gate insulating film. (For example, 80 to 200 angstroms).

By the way, in the first embodiment, the voltage applied between the electrodes of the storage capacitor is, as shown in FIG.
The difference between the image signal voltage Vd applied to the data line and the center potential Vc of the image signal is about 5 V (the LC common potential LC-COM applied to the common electrode 37 provided on the opposite substrate 38 of the liquid crystal panel in FIG. Although Vc is shifted from Vc by ΔV, the voltage actually applied to the pixel electrode is also Vd−ΔV shifted by ΔV). Therefore, in the first embodiment, the insulating film 3 immediately below the polysilicon or metal silicide layer forming one electrode 6 of the storage capacitor is used.
Is formed not at the same time as the gate insulating film of the pixel switching FET but at the same time as the gate insulating film of the FET constituting the peripheral circuit.
The capacitance value can be reduced by a factor of 1 to 5, thereby increasing the capacitance value by a factor of 3 to 5. 7 is a gate signal supplied to the gate electrode 4a of the pixel switching FET via the gate line 4.

The conductive layer 6, which is one electrode of the storage capacitor, is not a polysilicon or metal silicide layer forming a gate electrode of a pixel switching FET, but a MOSFET gate electrode forming a peripheral circuit. It may be constituted by a polysilicon or metal silicide layer.

FIGS. 3 and 4 show a second embodiment of the reflective electrode side substrate of the reflective liquid crystal panel to which the present invention is applied.
FIG. 3 is a cross-sectional view of the pixel switching MOSFET. In this embodiment, the switching M in the first embodiment is used.
The OSFET is a CMOS. 5a and 5b are source and drain regions of an N-channel MOSFET, and 4a
Is the gate electrode. These are the switching MOSFETs in the first embodiment except that they are formed on the surface of a P-well region 21 formed in the semiconductor substrate 1.
It has the same configuration as T.

On the other hand, in this embodiment, the N channel M
A P-channel MOSF
Source and drain regions 25a and 25b of ET and a gate electrode 24a thereof are formed. The source and drain regions 25a and 25b are P-type impurity introduction layers, and are formed on the N well region 22 formed on the substrate surface. P
The well region 21 and the N-well region 22 are formed so as to be continuous with pixels adjacent in the pixel row direction (gate line direction). The gate electrode 24a of the P-channel MOSFET is connected to the first gate line 4 on the N-channel MOSFET side.
Is formed so as to protrude from the second gate line 24 disposed in parallel with the first gate line 4, and a signal having a phase opposite to that of the signal applied to the first gate line 4 is applied to the second gate line 24, whereby the P channel The MOSFET and the N-channel MOSFET are simultaneously turned on and off.

The source and drain regions 25a and 25b of the P-channel MOSFET are N-channel MOSFETs.
Is formed in a self-aligned manner by ion-implanting a P-type impurity using the gate electrode 24a as a mask in a state where the top is covered with a resist or the like. In the illustrated embodiment, N channels M
Impurity introduction layer 5b constituting drain region of OSFET
To form a conductive layer 6 on the expanded portion 5b 'via an insulating film 3'.
By connecting to the P-type well region 21 via a and the P-type contact region 7 having a high impurity concentration, the potential is fixed. P-channel MOSFE
The T side has a configuration in which the drain region 25b is simply connected to the reflective electrode 12 via the contact hole 13.

The P well region 21 and the N well region 22 are formed so as to be continuous with the well regions of the adjacent pixel regions along the direction in which the gate lines 4 and 24 are arranged (scanning direction). Outside the P well region 2
1 is connected to a ground line for supplying a ground potential, and N well region 22 is connected to a power supply line for supplying a high power supply voltage Vcc. In FIG. 3, reference numeral 14 denotes a channel stopper layer.

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. further,
The source / drain regions of both MOSFETs are LDD
(Lightly doped drain) structure may be adopted. Note that the pixel switching FET may be offset (a structure in which a distance is provided between the gate electrode and the source / drain region) in consideration of being driven at a large voltage and having to prevent a leak current. .

In FIGS. 3 and 4, the storage capacitance is constituted by the N-type impurity introduction layer 5b 'and the introduction layer 6, but similarly, the P-type impurity introduction layer 25b is extended to form an extension 25b'. Then, a capacitor may be formed in both the P well and the N well by forming a conductive layer to which a potential is applied from the N well 22 via the insulating film 3.

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

As shown in FIG. 5, in this embodiment, a light-shielding film 26 for preventing light from entering a peripheral circuit provided on the peripheral portion of the substrate is provided.
The peripheral circuit is provided around a pixel region 20 in which the pixel electrodes are arranged in a matrix, and sequentially includes a data line driving circuit 31 and a gate line 4 which supply an image signal corresponding to image data to the data line 8. Gate line driving circuit 3 for scanning
2, a circuit such as an input circuit 34 for taking in image data input from the outside via the pad region 33, a timing control circuit 35 for controlling these circuits, and the like. These circuits are formed in the same process as the pixel electrode switching MOSFET. The MOSFET is formed as an active element or a switching element, and is combined with a load element such as a resistor or a capacitor.

In this embodiment, the light shielding film 26
Is composed of an aluminum layer formed in the same step as the pixel electrode 12 shown in FIG. 1, and is configured such that a predetermined potential such as a power supply voltage, a central potential of an image signal, or an LC common potential is applied. I have. By applying a predetermined potential to the light-shielding film 26, reflection can be reduced as compared with the case where the potential is floating or another potential.

FIG. 6 shows a sectional structure of a reflection type liquid crystal panel 30 to which the liquid crystal panel substrate is applied. As shown in FIG. 6, in the liquid crystal panel 30, a support substrate 36 made of glass, ceramic, or the like is bonded to the back surface of the semiconductor substrate 1 with an adhesive. At the same time, L
An incident-side glass substrate 38 having a counter electrode 37 made of a transparent conductive film (ITO) to which a C common potential is applied is arranged at an appropriate interval, and the periphery thereof is well-known in a gap sealed with a sealing material 39. (Twisted Nematic) type liquid crystal or SH (Super Homeotropic) type liquid crystal 40 in which liquid crystal molecules are almost vertically aligned in a state of no voltage application, to form a liquid crystal panel. It should be noted that a signal is input from the outside or the pad area 33 is formed by the sealing material 3
The position where the sealing material is provided is set so as to be outside of the reference numeral 9.

The light-shielding film 26 on the peripheral circuit is configured to face the counter electrode 37 with the liquid crystal 40 interposed. When the LC common potential is applied to the light shielding film 26, the LC common potential is applied to the opposing electrode 37, so that no DC voltage is applied to the liquid crystal interposed therebetween. Therefore, in the case of a TN type liquid crystal, the liquid crystal molecules are almost 9
The liquid crystal molecules are kept twisted by 0 °, and in the case of SH type liquid crystal, the liquid crystal molecules are always kept in a vertically aligned state.

In this embodiment, the strength of the liquid crystal panel substrate 30 made of a semiconductor substrate is significantly increased because the support substrate 36 made of glass or ceramic is bonded to the back surface thereof with an adhesive. As a result, if the support substrate 36 is bonded to the liquid crystal panel substrate 30 and then bonded to the counter substrate, there is an advantage that the gap becomes uniform over the entire panel.

FIG. 8 is an example of an electronic apparatus using the liquid crystal panel of the present invention. The main part of a projector (projection display device) using the reflective liquid crystal panel of the present invention as a light valve is viewed in plan. FIG. FIG. 8 is a cross-sectional view in the XZ plane passing through the center of the optical element 130. The projector of the present example is a polarized light illuminating device 10 that is generally configured by a light source unit 110, an integrator lens 120, and a polarization conversion element 130 arranged along the system optical axis L.
0, the S-polarized light beam emitted from the polarized light
The polarizing beam splitter 200 that reflects the polarized light beam reflecting surface 201, the dichroic mirror 412 that separates the blue light (B) component of the light reflected from the S-polarized reflecting surface 201 of the polarizing beam splitter 200, the separated blue light (B) is a reflection type liquid crystal light valve 300B that modulates blue light, a dichroic mirror 413 that reflects and separates a red light (R) component of a light beam after blue light is separated, and a separated red light ( R) modulating reflective liquid crystal light valve 300R, dichroic mirror 413
Reflective liquid crystal light valve 300G for modulating the remaining green light (G) passing through the three reflective liquid crystal light valves 3
The light modulated by 00R, 300G, and 300B is composed by a dichroic mirror 412, 413, and a polarization beam splitter 200, and is composed of a projection optical system 500 composed of a projection lens that projects the composite light on a screen 600. The above three reflective liquid crystal light valves 300
The above-described liquid crystal panels are used for R, 300G, and 300B, respectively.

The randomly polarized light beam emitted from the light source unit 110 is divided into a plurality of intermediate light beams by the integrator lens 120, and the polarization direction is substantially changed by the polarization conversion element 130 having the second integrator lens on the light incident side. After being converted into one kind of polarized light beam (S-polarized light beam), the light reaches the polarization beam splitter 200. The S-polarized light beam emitted from the polarization conversion element 130 is reflected by the S-polarized light beam reflection surface 2 of the polarizing beam splitter 200.
01, the blue light (B) of the reflected light is reflected by the blue light reflecting layer of the dichroic mirror 412 and modulated by the reflective liquid crystal light valve 300B. Also, dichroic mirror 411
Among the light beams transmitted through the blue light reflecting layer, the light beam of red light (R) is reflected by the red light reflecting layer of the dichroic mirror 413 and is modulated by the reflective liquid crystal light valve 300R.

On the other hand, the light flux of the green light (G) transmitted through the red light reflecting layer of the dichroic mirror 413 is modulated by the reflection type liquid crystal light valve 300G. Thus, each of the reflective liquid crystal light valves 300R, 300R
0G, 300B modulation reflection type liquid crystal light valve 3
The reflective liquid crystal panels of 00R, 300G, and 300B are provided with a TN type liquid crystal (a liquid crystal in which the long axis of liquid crystal molecules is oriented substantially parallel to the panel substrate when no voltage is applied) or an SH type liquid crystal (where the long axis of the liquid crystal molecules is A liquid crystal that is oriented substantially perpendicular to the panel substrate when no voltage is applied is employed.

When a TN type liquid crystal is employed, 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 (OFF). Pixel), the incident color light is elliptically polarized by the liquid crystal layer, is reflected by the reflective electrode, and passes through the liquid crystal layer.
The light is reflected and emitted as light in a state close to elliptically polarized light having a large polarization axis component substantially shifted by 90 degrees from the polarization axis of the incident color light.
On the other hand, in a pixel (ON pixel) applied with a voltage to the liquid crystal layer,
The incident color light reaches the reflective electrode as it is, 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 type liquid crystal changes according to the voltage applied to the reflective 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 transistor of the pixel. Variable.

When the SH type liquid crystal is adopted, the voltage applied to the liquid crystal layer is lower than the threshold voltage of the liquid crystal (OF).
F pixel), the incident color light reaches the reflection electrode as it is, is reflected, and is reflected and emitted with the same polarization axis as that at the time of incidence. On the other hand, in a pixel (ON pixel) to which a voltage is applied to the liquid crystal layer, the incident color light is elliptically polarized by the liquid crystal layer, reflected by the reflective electrode, and passes through the liquid crystal layer with respect to the polarization axis of the incident light. Is reflected and emitted as elliptically polarized light having a large polarization axis component shifted by about 90 degrees. As in the case of the TN type liquid crystal,
Since the alignment angle of the liquid crystal molecules of the TN type liquid crystal changes according to the voltage applied to the reflective 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 transistor of the pixel. Variable.

Of the color lights reflected from the pixels of the liquid crystal panel, the S-polarized light component does not pass through the polarization beam splitter 200 that reflects the S-polarized light, whereas the P-polarized light component does. An image is formed by the light transmitted through the polarizing beam splitter 200. Therefore, the projected image is T
When the N-type liquid crystal is used for the liquid crystal panel, 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, so that a normally white display is obtained. The reflected light 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 performed.

The reflection type liquid crystal panel has a TFT on a glass substrate.
Compared to an active matrix type liquid crystal panel having an array, the number of pixels can be formed more by using semiconductor technology, and the panel size can be made smaller, so that a high-definition image can be projected and a projector can be formed. Can be reduced in size.

As described with reference to FIG. 6, the peripheral circuit portion of the liquid crystal panel is covered with a light-shielding film, and has the same voltage (for example, an LC common potential or the same potential) together with a counter electrode formed at a position facing the counter substrate. If the potential is different from this, the potential may be different from that of the counter electrode of the pixel portion.
In this case, the peripheral counter electrode is separated from the counter electrode of the pixel portion. ) Is applied, approximately 0 V is applied to the liquid crystal interposed between them, and the liquid crystal becomes the same as the OFF state. Therefore, in the liquid crystal panel of the TN type liquid crystal, all the periphery of the image region can be displayed white in accordance with the normally white display, and in the liquid crystal panel of the SH type liquid crystal, the periphery of the image region can be entirely black in accordance with the normally black display. Can be displayed.

According to the above embodiment, the reflection type liquid crystal panel 1
The voltage applied to each of the pixel electrodes 11 to 113 is sufficiently maintained, and a clear image is obtained because the reflectance of the pixel electrodes is extremely high.

FIG. 9 is an external view showing an example of an electronic apparatus using the reflection type liquid crystal panel of the present invention.

FIG. 9A is a perspective view showing a mobile phone. 1000 denotes a mobile phone body, of which 100
Reference numeral 1 denotes a liquid crystal display unit using the reflection type liquid crystal panel of the present invention.

FIG. 9B is a diagram showing a wristwatch-type electronic device. 1100 is a perspective view showing the watch main body. 11
Reference numeral 01 denotes a liquid crystal display unit using the reflection type liquid crystal panel of the present invention. Since this liquid crystal panel has higher definition pixels than a conventional clock display unit, it can also display television images, and can realize a wristwatch type television.

FIG. 9C shows a portable information processing apparatus such as a word processor or a personal computer. 1200 denotes an information processing apparatus, 1202 denotes an input unit such as a keyboard, 120
Reference numeral 6 denotes a display unit using the reflective liquid crystal panel of the present invention;
Reference numeral 4 denotes an information processing apparatus main body. Since each electronic device is a battery-driven electronic device, the use of a reflective liquid crystal panel without a light source lamp can extend the battery life. Further, since the peripheral circuit can be built in the panel substrate as in the present invention, the number of components can be greatly reduced, and the weight and size can be further reduced.

[0063]

As described above, according to the present invention, a comparatively high impurity concentration serving as an active region (drain region) of an element (MOSFET) for switching a pixel electrode is provided on the surface of a semiconductor substrate below the pixel electrode serving as a reflective electrode. Is formed by expanding a high semiconductor region, and a conductive layer serving as one electrode of a storage capacitor is formed for each pixel above the semiconductor region via an insulating film, and the conductive layer is formed on the surface of the semiconductor substrate. The semiconductor substrate is electrically connected to a semiconductor substrate through a high-concentration semiconductor region of the same conductivity type as the semiconductor substrate, and the semiconductor substrate is electrically connected to a power supply layer that applies a constant potential outside the pixel region to reduce the potential. Since the capacitor is fixed, a large capacitance can be obtained with a relatively small area by forming a storage capacitor below the pixel electrode, and thus, the element can be reduced in size. In both cases, when the substrate potential is applied to one electrode of the storage capacitor, wiring for supplying a potential to one electrode of the storage capacitor is not required, so that the pixel structure is simplified and the yield is improved, There is an effect that unevenness on the surface of the insulating film is reduced and flattening of the reflective electrode is facilitated.

Further, since there is no capacitance line that intersects with the data line that supplies a signal applied to each pixel electrode, the parasitic capacitance of the data line can be reduced to reduce the load on the driver, and the storage capacitance has noise. And the potential of the storage capacitor is stabilized.

Further, the insulating film constituting the dielectric of the storage capacitor is an insulating film formed simultaneously with the gate insulating film provided between the gate electrode of the MOSFET and the channel region, and one electrode of the storage capacitor. As the conductive layer constituting the above, a conductive layer formed at the same time as the gate electrode of the MOSFET is used, so that a liquid crystal panel substrate having a storage capacitor having the above configuration is manufactured without increasing the number of process steps. There is an effect that can be.

Further, by using the switching element as a complementary transistor in which a P-channel transistor and an N-channel transistor are formed in one pixel, the level of a signal applied from the data line to the pixel electrode is reduced. As a result, the switching transistor can be turned on with a low gate voltage, so that the withstand voltage of the transistor can be reduced correspondingly, and the substrate can be manufactured by a low withstand voltage process.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a pixel region of a reflective electrode side substrate of a reflective liquid crystal panel to which the present invention is applied.

FIG. 2 is a plan layout diagram of a first embodiment of a pixel region of a reflective electrode side substrate of a reflective liquid crystal panel to which the present invention is applied.

FIG. 3 is a sectional view showing a second embodiment of the pixel region of the reflective electrode side substrate of the reflective liquid crystal panel to which the present invention is applied.

FIG. 4 is a plan layout diagram of a second embodiment of the pixel region of the reflective electrode side substrate of the reflective liquid crystal panel to which the present invention is applied.

FIG. 5 is a plan view showing a layout configuration example of a reflective electrode side substrate of the liquid crystal panel of the embodiment.

FIG. 6 is a cross-sectional view showing an example of a reflective liquid crystal panel to which the liquid crystal panel substrate of the embodiment is applied.

FIG. 7 is a waveform chart showing an example of a gate drive waveform and a data line drive waveform of a pixel electrode switching FET of a reflection type liquid crystal panel to which the present invention is applied.

FIG. 8 is a schematic configuration diagram of a video projector as an example of a projection display device in which the reflective liquid crystal panel of the embodiment is applied as a light valve.

FIGS. 9A, 9B, and 9C are external views each showing an example of an electronic apparatus using the reflective liquid crystal panel of the present invention.

FIG. 10 is a sectional view showing a configuration example of a pixel region of a reflective electrode side substrate of a reflective liquid crystal panel studied prior to the present invention.

FIG. 11 is a plan layout view of a configuration example of a pixel region of a reflective electrode side substrate of a reflective liquid crystal panel studied prior to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 semiconductor substrate 2 field oxide film 3 gate insulating film 3 ′ insulating film serving as dielectric of storage capacitor 4 gate line 4 a gate electrode 5 a, 5 b source / drain region 6 electrode (conductive layer) of storage capacitor 7 contact region 8 first Interlayer insulating film 9 Data line 10 Contact hole 11 Second interlayer insulating film 12 Reflection electrode (pixel electrode) 13 Contact hole 17 Power supply contact area A 19 Power supply layer 20 Pixel area 21 P-type well area 22 N-type well area 24 Second Gate lines 25a, 25b Source / drain regions of P-channel MOSFET 26 Light shielding film 30 Liquid crystal panel 31 Data line drive circuit 32 Gate line drive circuit 33 Pad region 34 Input circuit 35 Timing control circuit 36 Support substrate 37 Counter electrode 38 Glass on incident side Substrate 39 Sealing material 40 Liquid crystal 110 Source unit 200 polarizing beam splitter 300 light valve (reflection-type liquid crystal panel) 412, 413 dichroic mirror 500 the projection optical system 600 screen

Claims (8)

[Claims] 1. A method according to claim 1, wherein reflective electrodes are formed in a matrix on the semiconductor substrate, and switching elements are respectively formed corresponding to the respective reflective electrodes, so that a voltage is applied to the reflective electrodes via the switching elements. And a liquid crystal panel substrate provided with a storage capacitor for accumulating electric charge when the switching element is turned on for each pixel, wherein a semiconductor constituting the switching element is provided on a surface of the semiconductor substrate below the reflective electrode. A semiconductor region having a relatively high impurity concentration, which is continuous with the region and serves as one electrode of the storage capacitor, is formed. A conductive layer serving as the other electrode of the storage capacitor is provided above the semiconductor region via an insulating film for each pixel. The conductive layer is connected to a high impurity concentration contact region formed on the surface of the semiconductor substrate, and the contact region is Substrate for a liquid crystal panel, characterized by being configured to the same potential as the semiconductor substrate is applied to the conductive layer is. 2. The switching element is an insulated gate field effect transistor, and an insulating film forming a dielectric of the storage capacitor is formed simultaneously with a gate insulating film provided between a gate electrode and a channel region of the transistor. The substrate for a liquid crystal panel according to claim 1, wherein the substrate is an insulating film to be formed. 3. The switching element is an insulated gate field effect transistor, and the conductive layer forming the other electrode of the storage capacitor is a conductive layer formed simultaneously with the gate electrode of the transistor. The liquid crystal panel substrate according to claim 1 or 2, wherein 4. The switching element is an insulated gate field effect transistor, and a semiconductor region forming one electrode of the storage capacitor has an impurity formed simultaneously with an impurity introduction layer serving as a drain or source region of the transistor. 3. An introduction layer according to claim 1,
Or the substrate for a liquid crystal panel according to 3. 5. The switching element is a complementary transistor in which a P-channel transistor and an N-channel transistor are formed in one pixel, and the semiconductor region forming one electrode of the storage capacitor is 2. An impurity introducing layer formed simultaneously with an impurity introducing layer serving as a drain or source region of one of the complementary transistors.
The substrate for a liquid crystal panel according to 2, 3, or 4. 6. The substrate for a liquid crystal panel according to claim 1, wherein the substrate for a liquid crystal panel and the transparent substrate on the incident side having a counter electrode are arranged at an appropriate distance. A liquid crystal sealed in a gap between the liquid crystal panel and the transparent substrate. 7. An electronic apparatus comprising the liquid crystal panel according to claim 6 as a display unit. 8. A light source, a reflective liquid crystal panel configured to modulate light from the light source according to claim 5, and a projection lens for condensing and projecting light modulated by the liquid crystal panel. A projection display device.