JP4158242B2 - Optical writing type liquid crystal light valve device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical writing type liquid crystal light valve device, and is intended to improve sensitivity to writing light and improve spatial resolution in the optical writing type liquid crystal light valve device.
[0002]
[Prior art]
A liquid crystal light valve device (hereinafter referred to as LCLV) is an optical-optical image converter.
A light valve is a device configured to receive light with low light intensity and read and output an optical image in real time from light from another light source.
[0003]
LCLV has been used as an application for large screens for military and commercial purposes. For example, Rodney D Sterling et al. From Hughes published “Video-Rate Liquid Crystal Light-Valve Using an Amorphous Silicon Photo Detector”, SID, '90 Digest, Paper No. 17A 2, PP327-329 (1990) In the LCLV, a transparent electrode 2 is formed on a transparent first glass substrate 1 and a thick, continuous, homogeneous amorphous silicon (hereinafter referred to as a- A photoconductive layer 3 (referred to as Si) is formed, and a light blocking layer 4 such as CdTe and a dielectric mirror 5 as an optical reflecting layer are laminated thereon, and an alignment layer 6 is formed on the surface.
On the other hand, a transparent second glass substrate 7 is prepared, and a transparent electrode 8 and an alignment layer 9 are similarly formed thereon.
Then, the first and second glass substrates 1 and 7 are opposed to each other with the side on which the alignment layers 6 and 9 are formed facing inside, with a gap of about several μm, and liquid crystal is injected therebetween. Thus, the liquid crystal layer 10 is formed to constitute the LCLV.
[0004]
In this LCLV, the second glass substrate 7 side is an optical image observation side, and the reading light LR by polarized light is irradiated from the second glass substrate 7 side perpendicularly to the glass substrate 7. At this time, the readout light passes through the transparent electrode 7 and the liquid crystal layer 10 and is reflected by the dielectric mirror 5, and again passes through the liquid crystal layer 10 and the glass substrate 7, and is emitted to the outside. it can.
On the other hand, when the write light LW is irradiated from the first glass substrate 1 side while applying the AC voltage AC between the transparent electrodes 2 and 8 in a state where the read light LR is irradiated, the write light LW is The photoconductive layer 3 is irradiated through the first glass substrate 1 and the transparent electrode 2, and the photoconductive layer 3 is activated in this irradiated portion, generating electron-hole pairs. As a result, the capacitance of the photoconductive layer 3 increases according to the pattern according to the irradiation pattern of the writing light LW and the intensity, the resistance value decreases, and the voltage across the liquid crystal layer increases. This spatial change in voltage becomes a change in the orientation of liquid crystal molecules, causing birefringence and optical rotation in the readout light LR passing through the liquid crystal layer, and modulating the polarization orientation (polarization) of the readout light LR. . Therefore, the reading light finally emitted from the second glass substrate 7 can be observed as a change in the amount of light by passing it through the polarizing plate. That is, the pattern of the writing light LW, that is, an optical image corresponding to the optical image can be observed from the second glass substrate 7 side.
[0005]
The light blocking layer 4 is disposed between the dielectric mirror 5, that is, the light reflecting layer, and the photoconductive layer 3, so that even a slight amount of readout light that has passed through the light reflecting layer can be absorbed by this light. This read light is absorbed by the blocking layer 4 and arrives at the photoconductive layer 3 to activate the photoconductive layer and generate an elephant other than the write light, that is, to avoid noise generation. Is.
[0006]
By the way, in the above-mentioned LCLV, in order to obtain high sensitivity, it is desired to maximize the voltage applied to the liquid crystal layer in accordance with the change in the resistance value of the photoconductive layer 3. This maximization is achieved when the impedance of the photoconductive layer 3 not exposed to light and the impedance of the liquid crystal layer 10 satisfy the following conditions.
The condition is that the impedance of the equivalent circuit of the photoconductive layer 3 and the parallel circuit of the bulk resistor is approximately equal to or higher than the impedance of the parallel circuit of the same capacitor and resistor in the liquid crystal layer 10 (this condition). Hereinafter referred to as a balanced relationship).
In order to realize this balanced relationship, specifically, the film thickness of the photoconductive layer 3 made of a-Si is increased to about 30 μm.
[0007]
The reason why a thick film having a thickness of 30 μm is necessary is that when the relationship between the impedance of the photoconductive layer 3 and the liquid crystal layer 10 described above is set, the photoconductive layer 3 made of an a-Si film is required. This is because the dielectric constant is higher than the dielectric constant of the liquid crystal layer 10.
However, when the photoconductive layer of the a-Si layer is made as thick as 30 μm as described above, the charge generated in the photoconductive layer is easily diffused to the adjacent region due to the incidence of the write light described above.
[0008]
That is, in an ideal LCLV, the photoconductive layer has a high resistance enough to prevent the lateral diffusion of charges generated by light irradiation, but in an a-Si photoconductive layer, When the film thickness reaches about 30 μm, a sufficiently high resistance cannot be obtained, and charge diffusion in the lateral direction (plane direction) tends to occur, resulting in a decrease in spatial contrast and a decrease in resolution.
[0009]
In order to avoid such an inconvenience, an attempt has been made to increase the resistivity by adding a dopant to the a-Si layer constituting the photoconductive layer. This is because, when an a-Si film is formed, there is a property that an n-type dopant is naturally generated in the film, and this is offset by doping a p-type dopant such as boron. is there.
However, in this method, the effect of the addition of the dopant is extremely large, and the generation of the n-type dopant differs depending on the film formation of the a-Si, so that the p-type dopant for setting the target resistivity is used. Performing doping accurately is extremely difficult as a practical work, resulting in an increase in manufacturing cost and a decrease in yield.
[0010]
Therefore, a proposal has been made of a divided structure in which the photoconductive layer is completely separated for each pixel (US Pat. No. 5,076,670). This separation is, for example, by pattern etching by photolithography. As described above, pattern etching of a thick photoconductive layer having a thickness of 30 μm not only increases the working time but also provides a clear patterning. Becomes difficult. Further, an insulating material is embedded in the groove between the separated photoconductive layers, and the insulating material is embedded in the groove having a high aspect ratio (ratio of groove depth d to width w, d / w). The work is difficult, the cost is high, and the reliability is problematic.
[0011]
In addition, as shown in a schematic cross-sectional view in FIG. 17, a conductive layer 11 having a high reflectance and a low resistivity is selectively formed so as to face the transparent electrode 2 with the photoconductive layer 3 interposed therebetween, and adjacent conductive layers are formed. A structure in which an insulating layer 12 is formed between layers 11 has been proposed (in FIG. 17, parts corresponding to those in FIG. 16 are assigned the same reference numerals and redundant description is omitted).
In this case, there is an effect of accelerating the recovery of the charges generated in the photoconductive layer 3 by the conductive layer 11, and the readout light passing through the dielectric mirror 5 without providing the light blocking layer 4 in FIG. Is reflected and is not incident on the photoconductive layer 3.
However, even in this structure, since the facing area between the conductive layer 11 and the transparent electrode 2 facing each other with the photoconductive layer 3 interposed therebetween is large, in order to reduce the capacity of the photoconductive layer 3, There was no change in the situation that the photoconductive layer 3 needs to be thickened.
[0012]
Further, from the viewpoint of preventing charge diffusion between pixels, a structure in which a part is separated by an element isolation insulating layer region between elements of the photoconductive layer and the elements are not completely separated (US Pat. No. 4,913,531). However, this method alone can be expected to slightly reduce the diffusion of charges generated in the photoconductive layer by the write light to the adjacent device region. It has not been completely resolved. There is still a problem with the need for thick photoconductive layers.
[0013]
[Problems to be solved by the invention]
FIG. 18 shows a previously proposed optical writing type liquid crystal light valve device for the purpose of solving the above-mentioned problems.
As shown in FIG. 18, transparent first and second substrates 21 and 22, a photoconductive layer 23, and a first electrode 31 and a second electrode formed in contact with the photoconductive layer 23, respectively. The electrode 32, the optical reflection layer 24, the liquid crystal layer 27, and the third electrode 33 are included.
[0014]
The second electrode 32 is composed of divided electrode portions 32A divided into a plurality of electrode portions, and each divided electrode portion 32A is arranged substantially along the surface direction of the liquid crystal layer 27, that is, the second electrode 32 sandwiches the liquid crystal layer 27 therebetween. The counter electrode portion 32f constituting the counter electrode with the third electrode 33 and the contact portion 32c of the photoconductive layer 23 extending in the vertical direction therefrom.
The divided electrode portion 32A has a T-shaped cross section in which the contact portion 32c is formed in a direction extending in the vertical direction from the center of the counter electrode portion 32f.
[0015]
In each divided electrode portion 32A of the second electrode 32, the contact area of the contact portion 32c with the photoconductive layer 23 is selected to be sufficiently smaller than the area of the counter electrode portion 32f.
[0016]
Further, a part of the first electrode 31 is formed between the opposing electrode portions 32 f of the second electrode 32 so as to face each other.
[0017]
The second electrode 32 can substantially reduce the capacitance related to the photoconductive layer 23 by separating the counter electrode portion 32f from the photoconductive layer 23 as much as possible.
[0018]
Accordingly, the thickness of the photoconductive layer 23 that sets the above-described impedance balance relationship can be reduced, for example, to about 1 to 2 μm, which is a film thickness necessary for the absorption of the write light LW to the photoconductive layer 23. it can.
[0019]
In addition to this, it is possible to take measures to increase the apparent capacity of the liquid crystal layer 27 side.
That is, as shown in FIG. 19, the first electrode 31 and the second electrode 32 are arranged on one main surface 23S of the photoconductive layer 23 opposite to the substrate 21.
[0020]
In this structure, the first electrode 31 and the contact portion 32c of the second electrode 32 are juxtaposed with the photoconductive layer 23, so that the first electrode 31 and the second electrode 32 Since the facing through the photoconductive layer 23 is in a direction along the surface direction of the photoconductive layer 23, the substantial facing distance is thereby increased, and the capacitance associated with the photoconductive layer 23 is decreased.
[0021]
Further, as shown in FIG. 20, a fourth electrode 34 having the same electric potential as the third electrode 33 is provided between the arrangement surface of the counter electrode portion 32 f of the second electrode 32 and the photoconductive layer 23. By newly arranging and forming, the capacitance formed between the first electrode 31 and the fourth electrode 34 formed via the interlayer insulating layer 42 is added to the capacitance formed with the normal liquid crystal layer 27 interposed therebetween. In addition, the capacity related to the liquid crystal layer 27 can be substantially increased.
[0022]
Accordingly, by apparently increasing the capacitance on the liquid crystal layer 27 side with respect to the capacitance on the photoconductive layer 23 side that is increased by making the photoconductive layer 23 thinner, the impedances of both the liquid crystal layer 27 and the photoconductive layer 23 are increased. It becomes possible to perfectly balance.
[0023]
By using the above-described means, it is possible to maximize the voltage applied to the liquid crystal layer 27 in accordance with the change in the resistance value of the photoconductive layer 23 made of a-Si due to incident light.
[0024]
However, in the configuration shown in FIG. 20, even when the positional relationship between the second electrode 32 and the fourth electrode 34 is shifted, the facing area between the electrodes 32 and 34 may vary between devices. In order to avoid such a situation, it is necessary to form the second electrode 32 so as to overlap the fourth electrode 34 even when the positional relationship described above is shifted.
That is, the width of the fourth electrode 34 is set to
The width of the fourth electrode 34 = the width between the second electrodes 32 + the width necessary for forming the capacitance + the misalignment.
[0025]
On the other hand, if the width of the fourth electrode 34 is increased so that the second electrode 32 overlaps the fourth electrode 34, the fourth electrode 34 does not directly face the photoconductive layer 23. Although it is necessary to increase the width of the first electrode 31 in the lower layer, this reduces the charge generation region and lowers the sensitivity.
[0026]
That is, it can be said that there is a problem that the sensitivity of the LCLV device is lowered when the overlap is made so as to completely allow the misalignment between the second electrode 32 and the fourth electrode 34.
[0027]
On the contrary, if the fourth electrode 34 does not have a sufficient width for the above-mentioned misalignment, the capacitance between the electrodes 32 and 34 may vary, resulting in a decrease in product yield and image quality variation. Cause problems.
[0028]
In the present invention, in order to solve the above-mentioned problems, the voltage applied to the liquid crystal layer can be maximized even if the photoconductive layer is thinned to about 1 to 2 μm. Stabilize the coupling capacity of the pixel electrode and auxiliary electrode required to balance the capacitance with little variation, and achieve high sensitivity and high resolution, while reducing the manufacturing process difficulty and manufacturing cost. An optical writing type liquid crystal light valve device that can improve the above is provided.
[0029]
[Means for Solving the Problems]
The optical writing type liquid crystal light valve device of the present invention includes first and second transparent substrates, Formed on one main surface of the first transparent substrate Photoconductive layer and photoconductive layer On one main surface opposite to the first transparent substrate A first electrode disposed in contact with the first electrode and the photoconductive layer; Formed in contact with the same main surface and formed with an insulating layer between the first electrode At least a second electrode, an optical reflection layer, a liquid crystal layer, and a third electrode, and the second electrode includes a divided electrode portion divided into a plurality of electrode portions. A fourth electrode insulated from the first electrode is formed between the electrode and the first electrode, and further, a fourth electrode and a capacitor constituting a capacitor are formed between the second electrode and the fourth electrode. 5 electrodes are formed, and at least a part of the first electrode, the fourth electrode, and the fifth electrode is disposed at a position facing between the divided electrode portions of the second electrode.
[0030]
According to the configuration of the present invention described above, the fourth electrode and the fifth electrode are disposed between the second electrode and the fourth electrode by disposing the fourth electrode and the fifth electrode constituting the capacitor. Even if misalignment occurs in the electrodes, the facing area between the fourth electrode and the fifth electrode can be secured, and a stable inter-electrode capacitance can be secured.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
The present invention includes first and second transparent substrates; Formed on one main surface of the first transparent substrate Photoconductive layer and photoconductive layer On one main surface opposite to the first transparent substrate A first electrode disposed in contact with the first electrode and the photoconductive layer; Formed in contact with the same main surface and formed with an insulating layer between the first electrode The second electrode, the optical reflection layer, the liquid crystal layer, and the third electrode are provided, and the second electrode includes a divided electrode portion divided into a plurality of electrode portions. A fourth electrode insulated from the first electrode is formed between the first electrode and the first electrode, and a fourth electrode and a capacitor are formed between the second electrode and the fourth electrode. An optical writing type liquid crystal light valve device in which electrodes are formed, and at least a part of the first electrode, the fourth electrode, and the fifth electrode are disposed at positions facing each other between the divided electrode portions of the second electrode It is.
[0032]
According to the present invention, in the optical writing type liquid crystal light valve device, the fifth electrode Short side direction The width is wider than the width of the fourth electrode in the short side direction.
[0033]
According to the present invention, in the optical writing type liquid crystal light valve device, the fifth electrode Short side direction The width is narrower than the width of the fourth electrode in the short side direction.
[0034]
According to the present invention, in the above-described optical writing type liquid crystal light valve device, the fifth electrode Width in the short side direction Of the fourth electrode Short side direction The width is substantially the same in a self-aligning manner.
[0035]
According to the present invention, in the above-described optical writing type liquid crystal light valve device, the fifth electrode is formed so as to face at least the side and part of the upper portion of the fourth electrode.
[0036]
According to the present invention, in the above-described optical writing type liquid crystal light valve device, the contact portion between the fifth electrode and the second electrode is formed by the same contact portion as the contact portion between the second electrode and the photoconductive layer. The configuration is as follows.
[0037]
According to the present invention, in the optical writing type liquid crystal light valve device, the second electrode and the photoconductive layer are connected to each other through a buffer layer having the same material and thickness as the first electrode. .
[0038]
FIG. 1 is a schematic cross-sectional view of a main part of an embodiment of an optical writing type liquid crystal light valve device of the present invention.
FIG. 2 is a schematic plan view of a pixel region of the optical writing type liquid crystal light valve device of FIG.
[0039]
Also in the optical writing type liquid crystal light valve device of the present embodiment, a first transparent substrate 51 and a second transparent substrate 52 made of, for example, a glass substrate are prepared. The transparency in the first transparent substrate 51 and the second transparent substrate 52 means that the first transparent substrate 51 is transparent to the writing light LW, that is, exhibits a high transmittance. Needless to say, 52 is transparent to the readout light LR, that is, exhibits a high transmittance.
[0040]
A photoconductive layer 53 is formed on one main surface of the first transparent substrate 51, and a first electrode 61 and a divided electrode portion 62A divided into a plurality of electrode portions for each pixel, for example, are formed thereon. After the second electrode 62 is formed and the surface is planarized by a chemical mechanical polishing method, a reflective layer 54 having a dielectric mirror structure, for example, is further formed thereon, and liquid crystal alignment is formed on the surface. An alignment layer 55 is formed.
[0041]
Further, the third electrode 63 is formed over the entire surface of the liquid crystal layer 57 on one main surface of the second transparent substrate 52, and the alignment layer 56 in which the liquid crystal is similarly aligned on the surface. Is formed.
[0042]
Then, the alignment layers 55 and 56 side of the first transparent substrate 51 and the second transparent substrate 52 are opposed to each other, and the distance between the two is maintained at a predetermined distance by interposing glass beads (not shown), for example. Then, the periphery is sealed to form a flat space between the transparent substrates 51 and 52, and liquid crystal is injected into the liquid crystal layer 57.
[0043]
The photoconductive layer 53 is formed on the first transparent substrate 51 by, for example, forming an a-Si layer over the entire surface by sputtering, CVD (chemical vapor deposition), or the like.
[0044]
The first electrode 61 is formed, for example, in a lattice shape in which a metal layer such as Cr, W, or Al is formed on the photoconductive layer 53 by vapor deposition, sputtering, or the like, and a plurality of openings are formed at a predetermined interval by photolithography. Form into a pattern.
[0045]
Similarly to the configuration shown in FIGS. 19 and 20, since the first electrode 61 is formed on the photoconductive layer 53, adjacent carriers generated in the photoconductive layer 53 due to the incidence of the write light LW. It is possible to prevent diffusion to the pixel region and prevent a decrease in contrast between pixels.
[0046]
Then, a second electrode 62 is formed on the photoconductive layer 53.
The second electrode 62 is formed of, for example, a metal having a light blocking property with respect to writing light and reading light such as Al, Cr, and W.
[0047]
The split electrode portion 62A of the second electrode 62 has a contact portion 62c as a portion in the stacking direction of each layer, that is, a vertical portion in the drawing, and a counter electrode portion 62f as a portion in the main surface direction of each layer, that is, a horizontal portion in the drawing. It is configured. One end of the contact part 62 c is connected to the photoconductive layer 53.
[0048]
Between the split electrode portions 62A of the second electrode 62 and between the second electrode 62 and the photoconductive layer 53, for example, SiO 2 ₂ An interlayer insulating layer 58 such as SiN is formed, and the first electrode 61 and the second electrode 62 are insulated by the interlayer insulating layer 58.
[0049]
Then, the optical reflection layer 54 is formed on the entire surface of the second electrode 62. The optical reflection layer 54 can be formed by a so-called dielectric mirror having a normal multilayer structure, and the alignment layer 55 formed thereon can also have a normal structure.
[0050]
Further, the third electrode 63 formed on one main surface of the second transparent substrate 52 is formed by a transparent electrode layer such as ITO (indium tin oxide) as usual, and is formed thereon. The alignment layer 56 can also have a normal configuration.
[0051]
Further, similarly to the configuration shown in FIG. 20, a fourth electrode 64 having the same potential as that of the third electrode 63 is disposed so as to face the second electrode 62.
The fourth electrode 64 is insulated from the first electrode 61 and the second electrode 62 by the interlayer insulating layer 58.
Further, the fourth electrode 64 is formed with a width wider than that of the first electrode 61.
[0052]
In the present embodiment, in particular, a fifth electrode 65 that forms a counter capacitance with the fourth electrode 64 is disposed on the second electrode 62 side so as to face the fourth electrode 64.
The fifth electrode 65 is formed to have a width larger than the width of the fourth electrode 64, that is, the width in the short side direction of the fourth electrode 64 having a lattice pattern as shown in FIG.
The fifth electrode 65 is opposed to the counter electrode portion 62f of the divided electrode portion 62A of the two second electrodes 62 and between them, and is connected to one of the counter electrode portions 62f via a contact 66. In other words, one fifth electrode 65 is arranged and connected to each divided electrode portion 62A.
[0053]
As shown in FIG. 2, the fifth electrode 65 is opposed to the divided electrode portion 62A (counter electrode portion 62f) corresponding to, for example, two pixels adjacent in the vertical direction in the figure in plan view. Is formed.
In this case, the pattern of the fifth electrode 65 is not formed continuously like the pattern of the first electrode 61 or the fourth electrode 64 but is formed in a divided pattern.
[0054]
Furthermore, the width of the fifth electrode 65 is preferably set to be wider than the width of the fourth electrode 64 by at least the amount of misalignment between the electrodes 64 and 65.
Thereby, even if there is a misalignment, the fourth electrode 64 faces the fifth electrode 65 over the entire width.
Therefore, the capacitance of the second electrode 62 and the fourth electrode 64 formed by the fourth electrode 64 and the fifth electrode 65 can be stabilized.
[0055]
Similarly, the width of the fourth electrode 64 is preferably made wider than the width of the first electrode 61 by the amount of misalignment.
[0056]
The fourth electrode 64 and the fifth electrode 65 are formed by depositing a material such as a metal constituting the electrode over the entire surface of the interlayer insulating layer 58, and forming the desired pattern by resist patterning and etching. Can be done.
[0057]
In the present embodiment, the second electrode 62 is formed as follows.
After planarizing the surface of the interlayer insulating layer 58, a contact hole for the photoconductive layer 53 and a contact hole for the fifth electrode 65 are simultaneously opened, and after depositing, for example, a metal or the like so as to fill these contact holes Then, resist patterning and etching are performed to form the second electrode 62.
[0058]
According to the optical writing type liquid crystal light valve device of the present embodiment, the fourth electrode 64 and the fifth electrode 65 that forms a capacitor are arranged so as to face the fourth electrode 64, so that FIG. As shown in the figure, compared with the case where the capacitance is formed by the facing portion between the divided electrode portion 62A of the second electrode and the fourth electrode 64, the facing area constituting the capacitance is greatly changed by the misalignment of the two electrodes. Thus, it is possible to suppress variation in capacitance for each element.
[0059]
Furthermore, by making the width of the fifth electrode 65 wider than the width of the fourth electrode 64 in the short side direction, even if there is a misalignment, the facing area does not change, and the variation in capacitance is reduced. Can do.
[0060]
In the above-described embodiment, the fifth electrode 65 is formed to have a width larger than the width of the fourth electrode 64. However, the fifth electrode 65 is formed to have a width smaller than the width of the fourth electrode 64. Can do. The case is shown below.
[0061]
FIG. 3 shows a schematic cross-sectional view of the main part of another embodiment of the optical writing type liquid crystal light valve device of the present invention.
In the optical writing type liquid crystal light valve device of the present embodiment, the fifth electrode 65 is formed to have a width smaller than the width of the fourth electrode 64 (width in the short side direction).
Further, the first electrode 61 is formed to have a width larger than that of the fourth electrode 64.
That is, the width of the electrode
Width of first electrode 61> width of fourth electrode 64> width of fifth electrode 65
To be configured.
[0062]
Further, preferably, the width of each electrode 61, 64, 65 is set so that the difference between the electrodes 61, 64, 64, 65 is equal to or larger than the alignment deviation.
That is, the width of the previous embodiment is increased by an amount corresponding to the alignment deviation as it goes from the first electrode 61 to the fifth electrode 65, whereas in the present embodiment, the width is reduced. It is very different to go.
[0063]
In FIG. 3, the other parts corresponding to those in FIG.
[0064]
Also in this embodiment, as in the previous embodiment, the fourth electrode 64 is provided to increase the capacitance on the liquid crystal layer 57 side, and the fifth electrode 65 is provided to provide the fourth electrode. Even with the misalignment between the 64 and the fifth electrode 65, the change in the facing area of both the electrodes 64 and 65 is reduced, and the variation in capacitance is suppressed.
[0065]
Then, as described above, the width of the fifth electrode 65 is formed to be narrower than the width of the fourth electrode 64 by an amount equal to or greater than the misalignment of the electrodes 64 and 65. Even if there is a misalignment between the electrodes 65, the entire width of the fifth electrode 65 is necessarily opposed to the fourth electrode 64.
Accordingly, as long as the width of the fifth electrode 65 is accurately controlled, the capacitance variation between the electrodes is only due to the variation in the thickness of the interlayer insulating layer 58 between the electrodes. The main cause of misalignment can be eliminated.
[0066]
Note that the capacitance formed by the fourth electrode 64 and the fifth electrode 65 is defined by the fourth electrode 64 in the previous embodiment, whereas the fifth electrode in this embodiment. 65.
[0067]
A manufacturing process of the optical writing type liquid crystal light valve device of FIG. 3 will be described with reference to the schematic cross-sectional views of FIGS.
This manufacturing process is a manufacturing process suitable for eliminating the variation in capacitance due to the above-described misalignment of the three electrodes 61, 64, 65.
[0068]
First, as shown in FIG. 4A, on the photoconductive layer 53 formed on the first transparent substrate 51 made of glass or the like, for example, the first electrode 61, the insulating film 58 on the upper layer, the fourth electrode 64, The upper insulating film 58 and the fifth electrode 65 are continuously formed, and the fifth electrode 65 is patterned and etched with a resist 59.
Thereafter, the resist 59 on the fifth electrode 65 is removed.
[0069]
Next, as shown in FIG. 4B, a resist 59 is formed so as to cover the patterned fifth electrode 65, and patterning corresponding to a desired pattern of the fourth electrode 64 is performed on the resist 59.
At this time, the pattern of the resist 59 of the fourth electrode 64 is the fifth electrode 65 on the fifth electrode 65 so that the fifth electrode 65 is covered with the resist 59 even if there is an alignment misalignment during patterning. It is formed wider than the width of the electrode 65 (more than the pattern deviation).
[0070]
Then, as shown in FIG. 4C, the fourth electrode 64 and the insulating film 58 thereon are etched with the resist mask 59.
Thereafter, the resist 59 is removed.
[0071]
Next, as shown in FIG. 5D, a resist 59 is formed so as to cover the patterned fourth electrode 64 and fifth electrode 65, and a desired pattern of the first electrode 61 is formed on the resist 59. Perform the corresponding patterning.
At this time, the pattern of the resist 59 of the first electrode 61 is the fourth electrode 64 on the fourth electrode 64 so that the fourth electrode 64 is covered with the resist 59 even if there is an alignment misalignment during patterning. The electrode 64 is formed wider than the width of the electrode 64 (more than the pattern deviation).
[0072]
Then, as shown in FIG. 5E, the first electrode 61 and the insulating film 58 thereon are etched with the resist mask 59.
Thereafter, the resist 59 is removed.
As a result, the three electrodes 61, 64, 65 having a defined width are formed as described above.
[0073]
In the subsequent process, an interlayer insulating layer 58 is formed so as to cover the three electrodes 61, 64, 65 and the surface thereof is planarized. Then, a contact hole for the photoconductive layer 53 and a fifth hole are formed in the interlayer insulating layer 58. Contact holes for the electrodes 65 are simultaneously opened, and as shown in FIG. 5F, a second electrode 62 is formed by depositing a metal or the like so as to fill these contact holes.
[0074]
Thereafter, the optical writing type liquid crystal light valve device shown in FIG. 3 can be manufactured in the same manner as in the conventional manufacturing process.
[0075]
Next, FIG. 6 shows a schematic cross-sectional view of the main part of still another embodiment of the optical writing type liquid crystal light valve device of the present invention.
FIG. 7 is a schematic plan view of a pixel region of the optical writing type liquid crystal light valve device of FIG.
The optical writing type liquid crystal light valve device of the present embodiment has a configuration in which the fifth electrode 65 and the fourth electrode 64 are formed in substantially the same width in a self-aligning manner.
[0076]
The first electrode 61 is formed to have a width wider than those of the fourth electrode 64 and the fifth electrode 65.
Other configurations are the same as those of the embodiment shown in FIG. 1 and the embodiment shown in FIG.
[0077]
According to the optical writing type liquid crystal light valve device of the present embodiment, since the fifth electrode 65 and the fourth electrode 64 are formed in substantially the same width in a self-aligning manner, the electrodes 64 and 65 Since both are opposed across the entire width and the facing area is constant, the capacitance between both electrodes is constant.
[0078]
Next, the manufacturing process of the optical writing type liquid crystal light valve device shown in FIGS. 6 and 7 will be described with reference to the schematic cross-sectional views of FIGS.
This manufacturing process is a manufacturing process suitable for making the above-mentioned two electrodes 64 and 65 have substantially the same width in a self-aligning manner and making the capacitance constant.
8 to FIG. 11, a sectional view taken along line XX ′ (FIGS. 8A to 11A) and a sectional view taken along line YY ′ (FIGS. 8B to 11B) in the plan view of FIG. 7 are shown.
[0079]
As shown in FIGS. 8A and 8B, the first electrode 61, the insulating film 58 on the upper layer, and the fourth electrode 64 are formed on the photoconductive layer 53 formed on the first transparent substrate 51 made of glass or the like, for example. Then, the upper insulating film 58 and the fifth electrode 65 are continuously formed, and the fifth electrode 65 is patterned and etched with a resist 59.
At this time, as shown in FIG. 8B, in the YY ′ direction, the fourth electrode 64 and the fifth electrode are etched by the same resist mask 59 to form substantially the same width in a self-aligning manner.
[0080]
Next, as shown in FIG. 9A, in the XX ′ direction, patterning and etching with a resist 59 are performed in order to make the fifth electrode 65 have a predetermined length.
At this time, in the YY ′ direction shown in FIG. 9B, the pattern of the resist 59 is made wider than the widths of the fifth electrode 65 and the fourth electrode 64.
[0081]
Thereafter, the resist 59 on the fifth electrode 65 is once removed.
Then, as shown in FIGS. 10A and 10B, a resist 59 is formed so as to cover the surface, and etching is performed with a resist mask 59 having the width of the first electrode 61 in the YY ′ direction shown in FIG. 10B. Thus, the first electrode 61 having a predetermined width is formed.
[0082]
As the subsequent steps, as shown in FIGS. 11A and 11B, an interlayer insulating layer 58 is formed over the entire surface, the surface of the interlayer insulating layer 58 is planarized, and then the photoconductive layer 53 is formed. A contact hole and a contact hole for the fifth electrode 65 are simultaneously opened, the material of the second electrode 62 is formed so as to cover these contact holes, and the second electrode 62 is formed by flattening the surface.
[0083]
Thereafter, the optical writing type liquid crystal light valve device shown in FIG. 3 can be manufactured in the same manner as in the conventional manufacturing process.
[0084]
The processing pattern of the fourth electrode 64 and the fifth electrode 65 shown in FIG. 8B that defines the width of the fourth electrode 64 and the fifth electrode 65 and the length of the fifth electrode 65 by the manufacturing process described above. If the processing pattern of the fifth electrode 65 shown in FIG. 9A that defines the thickness is accurately controlled, the opposing areas of the two electrodes 64 and 65 can be made constant.
As a result, it is possible to eliminate the cause of misalignment, which has been the main cause of the variation in capacitance in the past, and only the variation in the film thickness of the insulating film 58 between the electrodes 64 and 65, which greatly increases the variation in capacitance. Can be reduced.
[0085]
Next, FIG. 12 shows a schematic cross-sectional view of the main part of another embodiment of the optical writing type liquid crystal light valve device of the present invention.
In the optical writing type liquid crystal light valve device of the present embodiment, the fifth electrode 65 is formed so as to cover the upper part and the side part of the fourth electrode.
[0086]
In the present embodiment, the first electrode 61 is formed to be wider than the fifth electrode 65.
Since other configurations are the same as those of the embodiment shown in FIG. 3, the same reference numerals are given and redundant description is omitted.
[0087]
According to the optical writing type liquid crystal light valve device of the present embodiment, the fifth electrode 65 is formed so as to cover the side portion and the upper portion of the fourth electrode 64, so that the fifth electrode 65 is It faces the upper part and part of the side part of the four electrodes 64.
[0088]
Thereby, even if there is a misalignment between the fifth electrode 65 and the fourth electrode 64, the facing area of both the electrodes 64 and 65 does not change.
Therefore, there is no problem that the capacitance fluctuates due to the misalignment between the fifth electrode 65 and the fourth electrode 64.
[0089]
In the present embodiment, the fifth electrode 65 is formed as follows, for example.
First, the material of the fourth electrode 64 is entirely formed on the insulating film 58, and resist patterning and etching are performed in a predetermined pattern to form the fourth electrode 64.
A thin insulating film is formed so as to cover the fourth electrode 64, and the material of the fifth electrode 65 is formed on the entire surface of the thin insulating film. At this time, the vicinity of the fourth electrode 64 is formed to be high.
Then, resist patterning and etching are performed on a predetermined pattern to form the fifth electrode 65 covering the side and the upper part of the fourth electrode.
[0090]
Next, FIG. 13 shows a schematic cross-sectional view of the main part of still another embodiment of the optical writing type liquid crystal light valve device of the present invention.
In the optical writing type liquid crystal light valve device of the present embodiment, the same contact portion is used as the contact portion between the fifth electrode 65 and the second electrode 62 and the contact portion between the photoconductive layer 53 and the second electrode 62. The contact portion 67 is used.
[0091]
In the present embodiment, the width of the first electrode 61, the fourth electrode 64, and the fifth electrode 65 is set to be wider as the upper layer electrode, as in the embodiment shown in FIG. It is formed to become.
Since other configurations are the same as those of the embodiment shown in FIG. 1, the same reference numerals are given and redundant description is omitted.
[0092]
According to the optical writing type liquid crystal light valve device of the present embodiment, since the same contact portion 67 is shared as described above, the contact portion is provided at one place and the contact portions are provided at two different places. Compared to the case, the area occupied by the contact portion can be reduced.
[0093]
When the contact portions are provided at two different locations, it is necessary to secure an area occupied by the two contact portions and to take a distance between the two contact portions. It is a restriction to provide two contact portions when attempting to reduce the size.
In other words, sharing the same contact portion 67 frees this restriction and has the advantage that the pixel size can be easily reduced.
[0094]
FIG. 14 shows a modified form of the configuration of FIG.
In the case of FIG. 14, the configuration in which the fifth electrode 65 covering the side portion and the upper portion of the fourth electrode 64 shown in FIG. 12 is applied to the configuration also serving as the contact shown in FIG. This has the same effect as the configuration of FIG. 13 described above.
[0095]
In the configuration shown in FIG. 13 and the configuration shown in FIG. 14, the width of the first electrode 61 (the width in the short side direction) is used to prevent the contact portion 67 and the first electrode 61 from short-circuiting. ) Is narrower than the width of the fifth electrode 65 so that it does not hit the first electrode 61 when the contact hole is opened.
[0096]
In the configuration shown in FIG. 13 and the configuration shown in FIG. 14, the above-described contact portion 67 is formed beside the fifth electrode 65 when a contact hole is opened in the interlayer insulating layer 58. A contact hole is also opened in a part on the fifth electrode 65.
Then, a material for the second electrode 62 is formed so as to fill the contact hole, and processing such as planarization of the surface is performed to form the second electrode 62 and the contact portion 67 configured by the divided electrode portion 62A. To do.
Thereby, the contact part 67 is also connected to a part on the fifth electrode 65, and the contact between the second electrode 62 and the fifth electrode 65 can be reliably obtained.
[0097]
Next, FIG. 15 shows a schematic cross-sectional view of a main part of another embodiment of the optical writing type liquid crystal light valve device of the present invention.
In the optical writing type liquid crystal light valve device of the present embodiment, one end of the contact portion 62c of the divided electrode portion 62A of the second electrode 62 is connected to the photoconductive layer 53 via the buffer film 60 instead of directly. It is.
The buffer film 60 is made of the same material as the first electrode 61 and has the same thickness.
[0098]
The buffer film 60 is patterned so that the pattern of the buffer film 60 remains in addition to the pattern of the first electrode 61 when the layer of the material of the first electrode 61 is pattern-etched. It can form by etching using.
[0099]
Since other configurations are the same as those of the embodiment shown in FIG. 1, the same reference numerals are given and redundant description is omitted.
[0100]
If a contact hole for opening the contact of the second electrode 62 to the photoconductive layer 53 is opened, if the photoconductive layer 53 is directly exposed to etching, the surface of the photoconductive layer 53 is roughened and contact characteristics are not good. May cause stability.
[0101]
Therefore, in this embodiment, since the photoconductive layer 53 and the second electrode 62 are connected via the buffer film 60 as described above, the contact hole is formed in advance when the contact hole is opened. Since the buffer film 60 is etched, it is possible to prevent the surface of the photoconductive layer 53 from being exposed to the etching and deteriorate the surface state, and to obtain stable contact characteristics.
[0102]
Further, if necessary, it is possible to select each material so that the buffer film 60 made of the same material as the first electrode 61 and the second electrode 62 are connected by the same kind of metal-metal contact. In this case, a stable contact can be obtained very easily as compared with the case where the photoconductive layer 53 and the second electrode 62 are in direct contact.
[0103]
The buffer film 60 can be applied to the embodiments shown in FIGS. 1, 3, 6, and 12 to 14, and the configurations shown in FIGS. 19 and 20, and is similarly stable. Contact characteristics can be obtained.
[0104]
The optical writing type liquid crystal light valve device of the present invention is not limited to the above-described embodiment, and various other configurations can be taken without departing from the gist of the present invention.
[0105]
【The invention's effect】
According to the above-described optical writing type liquid crystal light valve device according to the present invention, the capacitance variation between the electrodes due to the misalignment of the electrodes is eliminated, so that the capacitance balance between the liquid crystal layer and the photoconductive layer is always kept stable. In addition, the threshold of the liquid crystal, that is, the variation in characteristics as the liquid crystal light valve device is reduced, and the yield in manufacturing is greatly improved.
[0106]
Furthermore, since it is not necessary to make the first electrode on the photoconductive layer wide in order to suppress the influence of misalignment, the sensitivity can be improved.
[0107]
Also, the fifth electrode Short side direction Width is the short side direction of the fourth electrode Width of Narrower width or short-side direction of the fourth electrode Width of Wider width or fourth electrode Width in the short side direction When the same width is set in a self-aligned manner, one of the fourth electrode and the fifth electrode can be opposed to the other electrode over the entire width, so that the facing area changes even if misalignment occurs. As a result, variation in capacity can be suppressed.
[0108]
Further, when the contact portion between the fifth electrode and the second electrode and the contact portion between the second electrode and the photoconductive layer are constituted by the same contact portion, the area occupied by the contact portion is reduced. This makes it easy to reduce the pixel size and improve the image quality.
[0109]
In addition, when the second electrode and the photoconductive layer are connected via a buffer layer having the same material and thickness as the first electrode, the photoconductive layer is formed when the contact hole is opened. It is possible to prevent the surface from being exposed to etching and deteriorate the surface state, and to obtain stable contact characteristics.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a main part of an embodiment of an optical writing type liquid crystal light valve device according to the present invention.
2 is a schematic plan view of a pixel region of the optical writing type liquid crystal light valve device of FIG. 1. FIG.
FIG. 3 is a schematic cross-sectional view of a main part of another embodiment of the optical writing type liquid crystal light valve device according to the present invention.
4 is a schematic cross-sectional view showing a manufacturing process of the optical writing type liquid crystal light valve device of FIG.
5 is a schematic cross-sectional view showing a manufacturing process of the optical writing type liquid crystal light valve device of FIG. 2; FIG.
FIG. 6 is a schematic cross-sectional view of a main part of still another embodiment of the optical writing type liquid crystal light valve device according to the present invention.
7 is a schematic plan view of a pixel region of the optical writing type liquid crystal light valve device of FIG. 1. FIG.
8A and 8B are schematic cross-sectional views showing a manufacturing process of the optical writing type liquid crystal light valve device of FIG.
9A and 9B are schematic cross-sectional views illustrating manufacturing steps of the optical writing type liquid crystal light valve device of FIG.
10A and 10B are schematic cross-sectional views showing a manufacturing process of the optical writing type liquid crystal light valve device of FIG.
11A and 11B are schematic cross-sectional views showing a manufacturing process of the optical writing type liquid crystal light valve device of FIG.
FIG. 12 is a schematic sectional view of a main part of another embodiment of the optical writing type liquid crystal light valve device according to the present invention.
FIG. 13 is a schematic cross-sectional view of a main part of still another embodiment of the optical writing type liquid crystal light valve device according to the present invention.
14 is a schematic cross-sectional view of a main part of a form in which the optical writing type liquid crystal light valve device of FIG. 13 is partially modified.
FIG. 15 is a schematic cross-sectional view of a substantial part of another embodiment of the optical writing type liquid crystal light valve device according to the present invention.
FIG. 16 is a schematic cross-sectional view of a main part of a conventional optical writing type liquid crystal light valve device.
FIG. 17 is a schematic cross-sectional view of a main part of a conventional optical writing type liquid crystal light valve device.
FIG. 18 is a schematic cross-sectional view of the main part of the previously proposed optical writing type liquid crystal light valve device.
FIG. 19 is a schematic cross-sectional view of the main part of the previously proposed optical writing type liquid crystal light valve device.
FIG. 20 is a schematic cross-sectional view of a main part of the previously proposed optical writing type liquid crystal light valve device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st glass substrate, 2, 8 ... Transparent electrode, 3 ... Photoconductive layer, 4 ... Light shielding layer, 5 ... Dielectric mirror, 6, 9 ... Orientation layer, 7 ... 2nd glass substrate, 10 ... Liquid crystal layer, 11 ... conductive layer, 12 ... insulating layer, 21 ... first transparent substrate, 22 ... second transparent substrate, 23 ... photoconductive layer, 24 ... reflective layer, 25, 26 ... alignment layer, 27 ... liquid crystal Layer, 28 ... insulating layer, 31 ... first electrode, 32 ... second electrode, 32A ... divided electrode portion, 33 ... third electrode, 34 ... fourth electrode, 51 ... first transparent substrate, 52 ... second transparent substrate, 53 ... photoconductive layer, 54 ... light reflecting layer, 55, 56 ... alignment layer, 57 ... liquid crystal layer, 58 ... interlayer insulating layer, 59 ... resist, 60 ... buffer film, 61 ... first 62 ... second electrode, 62A ... divided electrode portion, 62c ... contact portion, 62f ... counter electrode portion, 63 ... third electrode, 64 ... first Electrode, 65 ... fifth electrode, 66, 67 ... contact portion, LW ... writing light, LR ... reading light

Claims (8)

First and second transparent substrates;
A photoconductive layer formed on one main surface of the first transparent substrate ;
A first electrode disposed in contact with one main surface of the photoconductive layer opposite to the first transparent substrate ;
A second electrode formed in contact with the same main surface of the first electrode and the photoconductive layer and formed between the first electrode and an insulating layer ;
An optical reflective layer;
A liquid crystal layer;
And at least a third electrode,
The second electrode includes a divided electrode portion divided into a plurality of electrode portions,
A fourth electrode insulated from the first electrode is formed between the second electrode and the first electrode,
Between the second electrode and the fourth electrode, a fifth electrode constituting a capacitance with the fourth electrode is formed,
The optical writing type, wherein at least a part of the first electrode, the fourth electrode, and the fifth electrode is disposed at a position facing between the divided electrode portions of the second electrode. Liquid crystal light valve device. 2. The optical writing type liquid crystal light valve device according to claim 1, wherein the width of the fifth electrode in the short side direction is wider than the width of the fourth electrode in the short side direction. 2. The optical writing type liquid crystal light valve device according to claim 1, wherein the width of the fifth electrode in the short side direction is narrower than the width of the fourth electrode in the short side direction. 2. The optical writing type according to claim 1, wherein the width of the fifth electrode in the short side direction is substantially the same as the width of the fourth electrode in the short side direction in a self-aligning manner. Liquid crystal light valve device.   2. The optical writing type liquid crystal light valve device according to claim 1, wherein the fifth electrode is formed so as to face at least a part of the side and upper part of the fourth electrode.   3. The contact portion between the fifth electrode and the second electrode is formed by the same contact portion as the contact portion between the second electrode and the photoconductive layer. Light writing type liquid crystal light valve device.   6. The contact portion between the fifth electrode and the second electrode is formed by the same contact portion as the contact portion between the second electrode and the photoconductive layer. Light writing type liquid crystal light valve device.   2. The photo-writing type liquid crystal according to claim 1, wherein the second electrode and the photoconductive layer are connected to each other through a buffer layer having the same material and thickness as the first electrode. Light valve device.

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