JP2005031196A - Liquid crystal device, method for manufacturing the same, and electronic apparatus - Google Patents

Abstract

An object of the present invention is to provide a desired pretilt angle with excellent reliability without dust generation and contamination.
A first and second liquid crystal substrates arranged opposite to each other, a liquid crystal sandwiched between the first and second liquid crystal substrates, and an alignment-treated porous film 81 are in contact with the liquid crystal. Thus, the alignment films 16 and 22 are provided on at least one of the first and second liquid crystal substrates, respectively.
[Selection] Figure 1

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal device capable of expressing a desired pretilt angle, a manufacturing method thereof, and an electronic apparatus.
[0002]
[Prior art]
The liquid crystal device is configured by sealing liquid crystal between two substrates such as a glass substrate and a quartz substrate. In a liquid crystal device, active elements such as thin film transistors (hereinafter referred to as TFTs) are arranged in a matrix on one substrate, a counter electrode is arranged on the other substrate, and sealed between both substrates. An image can be displayed by changing the optical characteristics of the liquid crystal layer according to the image signal.
[0003]
That is, an image signal is supplied to pixel electrodes (ITO) arranged in a matrix by TFT elements, and a voltage based on the image signal is applied to the liquid crystal layer between the pixel electrode and the counter electrode to change the arrangement of liquid crystal molecules. Let As a result, the transmittance of the pixel is changed, and light passing through the pixel electrode and the liquid crystal layer is changed according to the image signal to perform image display.
[0004]
In order to define the alignment of liquid crystal molecules when no voltage is applied, an alignment film is formed on the surface of one substrate (active matrix substrate (also referred to as element substrate)) and the other substrate (counter substrate) in contact with the liquid crystal layer. The alignment film is rubbed. By rubbing, liquid crystal molecules when no voltage is applied are aligned in the rubbing direction. For example, when a rubbing process in which the element substrate and the counter substrate are twisted by 90 degrees is performed, the liquid crystal molecules continuously change directions in the liquid crystal panel, and the substrates are arranged in different directions by 90 degrees.
[0005]
Polarizers are provided on the front and back surfaces of the liquid crystal panel, and only a predetermined polarization component of the incident light is allowed to pass through. In the normally white mode, the polarization axes of the polarizing plates on the front surface and the back surface of the liquid crystal panel are made to differ by 90 degrees to match the rubbing direction of the substrate. If it does so, the light which injected through the polarizing plate of the back surface of a liquid crystal panel will rotate 90 degree | times according to the arrangement | sequence of a liquid crystal molecule in a liquid crystal layer at the time of no voltage application, and will be radiate | emitted through a polarizing plate from the front surface of a liquid crystal panel. Thereby, white display is performed.
[0006]
When a voltage is applied to the liquid crystal, the alignment direction of the liquid crystal changes, that is, the major axis direction of the liquid crystal molecules is tilted according to the voltage, and the rotation of the vibration direction of the light by the liquid crystal in the liquid crystal panel is limited. The emitted light is absorbed by the polarizing plate. An image is displayed by applying a voltage corresponding to the image signal to the liquid crystal and transmitting light with a transmittance corresponding to the image signal.
[0007]
As described above, the alignment of the liquid crystal molecules when no voltage is applied is determined by forming an alignment film and performing a rubbing treatment. The alignment film is formed, for example, by applying polyimide with a thickness of about several tens of nanometers. By forming an alignment film on the surfaces of both substrates facing the liquid crystal layer, the liquid crystal molecules can be aligned along the substrate surface. In the rubbing process, fine grooves are formed on the surface of the alignment film to form an alignment anisotropic film, and the alignment of liquid crystal molecules can be defined by performing a rubbing process in a certain direction on the alignment film.
[0008]
In addition, in order to make the direction in which the tilt angle of the liquid crystal molecules changes when a voltage is applied between all the liquid crystal molecules, the major axis of the liquid crystal molecules is set to a predetermined angle (pretilt angle) with respect to the substrate when no voltage is applied. It is inclined and arranged.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-296528
[Problems to be solved by the invention]
By the way, the rubbing treatment is performed by attaching a rubbing cloth such as rayon around the roller, placing the rubbing roll in contact with the polyimide film on the liquid crystal substrate, and moving the rubbing roll while rotating to rub the polyimide film. An alignment film subjected to the alignment treatment is obtained. However, the alignment treatment by rubbing physically contacts the alignment film such as polyimide and the rubbing cloth, and is likely to generate dust and contamination.
[0011]
Therefore, Patent Document 1 discloses a technique for performing an alignment process by irradiating an organic polyimide film with an ion beam.
[0012]
However, with the alignment method by ion beam irradiation of Patent Document 1, it is possible to develop a relatively low pretilt angle, but it is difficult to develop a sufficiently high pretilt angle. Moreover, since the polyimide film targeted by the apparatus of Patent Document 1 is an organic film, the film quality is low in reliability.
[0013]
Even in the apparatus of Patent Document 1, when an organic film such as polyimide is used as an alignment film, it is possible to develop a certain pretilt angle, but it is necessary when an inorganic film is used as the alignment film. It is impossible to develop a pretilt angle.
[0014]
The present invention has been made in view of such problems, and by using a porous film of an inorganic film as well as an organic film, it can be obtained in any of horizontal alignment and vertical alignment by non-contact alignment treatment. It is an object of the present invention to provide a liquid crystal device capable of exhibiting a pretilt angle, a manufacturing method thereof, and an electronic apparatus.
[0015]
[Means for Solving the Problems]
The liquid crystal device according to the present invention is constituted by first and second liquid crystal substrates arranged opposite to each other, liquid crystal sandwiched between the first and second liquid crystal substrates, and an oriented porous film. And an alignment film provided on at least one of the first and second liquid crystal substrates so as to be in contact with the liquid crystal.
[0016]
According to such a configuration, the alignment film is formed by performing an alignment process on the porous film. By the orientation treatment, the pores in the porous film are configured to be inclined by a predetermined inclination angle with respect to the surface of the porous film. The pretilt angle is expressed in the liquid crystal molecules due to the inclination of the holes on the surface of the alignment film. By the orientation treatment, the inclination angle of the holes can be arbitrarily set, and a desired pretilt angle can be obtained. In this case, the alignment treatment of the alignment film can be performed in a non-contact manner, and dust generation and contamination can be prevented.
[0017]
In addition, the alignment film causes the liquid crystal molecules to exhibit a desired pretilt angle by changing the porosity and diameter of the porous film and at least one of the conditions of the alignment treatment. And
[0018]
According to such a configuration, a desired pretilt angle can be expressed by changing at least one setting of the porosity and diameter of the porous film and each condition of the alignment treatment.
[0019]
The porous film has a porosity of 20 to 70%, and each pore has a diameter of 1 nm to 50 nm.
[0020]
According to such a configuration, a desired pretilt angle can be surely expressed by inclining the holes by the alignment treatment.
[0021]
The porous film is an inorganic film.
[0022]
According to such a structure, even if it is an inorganic film, a desired pretilt angle can be obtained and an apparatus with excellent reliability can be configured.
[0023]
The porous film is formed by any one of a sol-gel method, a sputtering method, a vapor deposition method, a plasma CVD method, and a laser ablation method.
[0024]
According to such a configuration, a porous film can be reliably formed using these methods.
[0025]
Further, the orientation process is an anisotropic etching process.
[0026]
According to such a configuration, the porous film can be reliably subjected to orientation treatment by anisotropic etching.
[0027]
The alignment film may be formed by subjecting the porous film to anisotropic etching of either ion beam irradiation or plasma etching.
[0028]
According to such a configuration, the pores of the porous film can be reliably tilted using these methods.
[0029]
The method for manufacturing a liquid crystal device according to the present invention includes a step of forming a porous film on at least one of the first and second liquid crystal substrates arranged to face each other, and anisotropic etching into the porous film shape. And a step of forming an alignment film.
[0030]
According to such a configuration, the porous film is formed on at least one of the first and second liquid crystal substrates. The porous film is subjected to anisotropic etching. Thereby, the void | hole in a porous film inclines with respect to the film | membrane surface, and can express a desired pretilt angle.
[0031]
The step of forming the porous film employs any one of a sol-gel method, a sputtering method, a vapor deposition method, a plasma CVD method, and a laser ablation method.
[0032]
According to such a configuration, a porous film can be reliably formed using these methods.
[0033]
Further, the step of forming the alignment film by performing anisotropic etching includes one of ion beam irradiation and plasma etching.
[0034]
According to such a configuration, the pores of the porous film can be reliably tilted using these methods.
[0035]
An electronic apparatus according to the present invention is configured using the liquid crystal device manufactured by the liquid crystal device or the method for manufacturing the liquid crystal device.
[0036]
According to such a configuration, a desired pretilt angle can be expressed, and high-quality image display excellent in reliability without dust generation and contamination is possible.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view for explaining an alignment film of a liquid crystal device according to an embodiment of the present invention. This embodiment is applied to a liquid crystal device using a TFT substrate. FIG. 2 is a plan view of the liquid crystal device according to the present embodiment as viewed from the counter substrate side together with the components formed thereon. FIG. 3 is a cross-sectional view of the liquid crystal device after the assembly process in which the TFT substrate, which is an active matrix substrate, and the counter substrate are bonded together to enclose the liquid crystal is completed, cut along the line HH ′ in FIG. . FIG. 4 is an equivalent circuit diagram of various elements and wirings in a plurality of pixels constituting the pixel region of the liquid crystal device of the present embodiment. FIG. 5 is a cross-sectional view showing in detail the pixel structure of the liquid crystal device of FIGS. FIG. 6 is a flowchart showing the assembly process of the liquid crystal device, and FIG. 7 is a flowchart showing the alignment processing in the present embodiment. 8 to 10 are flowcharts showing specific examples of the alignment process. In each of the above drawings, the scale is different for each layer and each member so that each layer and each member can be recognized in the drawing.
[0038]
In the present embodiment, a porous film is used as an alignment film, and an alignment process is performed in a non-contact manner by anisotropic etching, thereby enabling expression of an arbitrary pretilt angle within a sufficient range.
[0039]
First, the overall configuration of the liquid crystal device of the present embodiment will be described with reference to FIGS.
[0040]
As shown in FIGS. 2 and 3, the liquid crystal device includes a TFT substrate 10 made of, for example, a quartz substrate, a glass substrate, or a silicon substrate, and a counter substrate 20 made of, for example, a glass substrate or a quartz substrate. The liquid crystal 50 is sealed between the two. The TFT substrate 10 and the counter substrate 20 that are arranged to face each other are bonded together by a sealing material 41.
[0041]
On the TFT substrate 10, pixel electrodes (ITO) 9a constituting pixels are arranged in a matrix. A counter electrode (ITO) 21 is provided on the entire surface of the counter substrate 20. On the pixel electrode 9a of the TFT substrate 10, an alignment film 16 subjected to an alignment process is provided. On the other hand, an alignment film 22 subjected to an alignment process is also provided on the counter electrode 21 formed over the entire surface of the counter substrate 20. In the present embodiment, the alignment films 16 and 22 are formed by subjecting a porous film to anisotropic etching, as will be described later.
[0042]
FIG. 4 shows an equivalent circuit of elements on the TFT substrate 10 constituting the pixel. As shown in FIG. 4, in the pixel region, a plurality of scanning lines 3a and a plurality of data lines 6a are wired so as to intersect with each other, and a pixel electrode is formed in a region partitioned by the scanning lines 3a and the data lines 6a. 9a are arranged in a matrix. A TFT 30 is provided corresponding to each intersection of the scanning line 3 a and the data line 6 a, and the pixel electrode 9 a is connected to the TFT 30.
[0043]
The TFT 30 is turned on by the ON signal of the scanning line 3a, whereby the image signal supplied to the data line 6a is supplied to the pixel electrode 9a. A voltage between the pixel electrode 9 a and the counter electrode 21 provided on the counter substrate 20 is applied to the liquid crystal 50. In addition, a storage capacitor 70 is provided in parallel with the pixel electrode 9a, and the storage capacitor 70 makes it possible to hold the voltage of the pixel electrode 9a for a time that is, for example, three orders of magnitude longer than the time when the source voltage is applied. The storage capacitor 70 improves the voltage holding characteristic and enables image display with a high contrast ratio.
[0044]
A plurality of pixel electrodes 9a are provided in a matrix on the TFT substrate 10, and data lines 6a and scanning lines 3a are provided along the vertical and horizontal boundaries of the pixel electrodes 9a. As will be described later, the data line 6a has a laminated structure including an aluminum film, and the scanning line 3a is made of, for example, a conductive polysilicon film. The scanning line 3a is formed so as to face a channel region 1a ′ described later. That is, the pixel switching TFT 30 is configured by arranging the gate electrode connected to the scanning line 3a and the channel region 1a ′ to face each other at the intersection of the scanning line 3a and the data line 6a.
[0045]
FIG. 5 is a schematic cross-sectional view of a liquid crystal device focusing on one pixel.
[0046]
Grooves 11 are formed in a lattice pattern on an element substrate 10 such as glass or quartz. A TFT 30 having an LDD (Lightly Doped Drain) structure is formed on the trench 11 via the lower light shielding film 12 and the first interlayer insulating film 13. The groove 11 facilitates flattening of the boundary surface between the TFT substrate and the liquid crystal 50.
[0047]
The TFT 30 includes a scanning line 3a that forms a gate electrode through a gate insulating film 2 on a semiconductor layer 1a in which a channel region 1a ', a source region 1d, and a drain region 1e are formed. The scanning line 3a is formed to be wide at a portion to be a gate electrode, and the channel region 1a ′ is configured in a region where the semiconductor layer 1a and the scanning line 3a face each other.
[0048]
On the element substrate 10, a plurality of transparent pixel electrodes 9a are provided in a matrix, and data lines 6a and scanning lines 3a are provided along vertical and horizontal boundaries of the pixel electrodes 9a. The lower light-shielding film 12 is provided in a lattice shape corresponding to each pixel along the data line 6a and the scanning line 3a. The light shielding film 12 prevents reflected light from entering the channel region 1 a, the source region 1 d, and the drain region 1 e of the TFT 30.
[0049]
The lower light-shielding film 12 includes, for example, a metal simple substance, an alloy, a metal silicide, a polysilicide, or a laminate of at least one of refractory metals such as Ti, Cr, W, Ta, Mo, and Pb. Etc.
[0050]
A second interlayer insulating film 14 is stacked on the TFT 30, and an island-shaped first intermediate conductive layer 15 extending in the scanning line 3 a and data line 6 a directions is formed on the second interlayer insulating film 14. On the first intermediate conductive layer 15, the capacitor line 18 is disposed opposite to the dielectric film 17.
[0051]
The first intermediate conductive layer 15 acts as a pixel potential side capacitance electrode (lower capacitance electrode) connected to the high concentration drain region 1e of the TFT 30 and the pixel electrode 9a, and a part of the capacitance line 18 serves as a fixed potential side capacitance electrode. Works.
[0052]
The capacitor line 18 has a multilayer structure of an upper capacitor electrode and a light shielding layer, and is disposed opposite to the first intermediate conductive layer 15 via the dielectric film 17 to constitute a storage capacitor (storage capacitor 70 in FIG. 4). In addition, it has a light blocking function for preventing internal reflection of light. The intermediate conductive layer 15 is formed at a position relatively close to the semiconductor layer, so that irregular reflection of light can be efficiently prevented.
[0053]
The capacitor line 18 has a multilayer structure in which an upper capacitor electrode made of, for example, a conductive polysilicon film and a light shielding layer made of a metal silicide film containing a refractory metal or the like are laminated. For example, the capacitor line 18 is constituted by a polycide of a light shielding layer made of silicide of tungsten, molybdenum, titanium, or tantalum and an upper capacitor electrode made of N-type polysilicon. As a result, the capacitor line 18 functions as a fixed potential side capacitor electrode as well as a built-in light shielding film.
[0054]
The first intermediate conductive layer 15 is made of, for example, a conductive polysilicon film and functions as a pixel potential side capacitor electrode. The first intermediate conductive layer 15 has a function as a light absorbing layer disposed between the capacitor line 18 as the built-in light shielding film and the TFT 30 in addition to the function as the pixel potential side capacitor electrode, and further, the pixel electrode 9a. And the high-concentration drain region 1e of the TFT 30 have a function of relay connection. The first intermediate conductive layer 15 may also be composed of a single layer film or a multilayer film containing a metal or an alloy, like the capacitor line 18.
[0055]
The dielectric film 17 disposed between the first intermediate conductive layer 15 as the lower capacitor electrode and the capacitor line 18 constituting the upper capacitor electrode is, for example, a relatively thin HTO (High Temperature Oxide) having a thickness of about 5 to 200 nm. ) Film, a silicon oxide film such as an LTO (Low Temperature Oxide) film, or a silicon nitride film. From the viewpoint of increasing the storage capacity, it is better that the dielectric film 17 is thinner as long as the reliability of the film is sufficiently obtained.
[0056]
The capacitor line 18 extends from the image display area in which the pixel electrode 9a is disposed to the periphery thereof, and is electrically connected to a constant potential source to be a fixed potential. As such a constant potential source, a later-described scanning line driving circuit 63 for supplying a scanning signal for driving the TFT 30 to the scanning line 3a and a later-described data line for controlling a sampling circuit for supplying an image signal to the data line 6a. A constant potential source such as a positive power source or a negative power source supplied to the drive circuit 61 may be used, or a constant potential supplied to the counter electrode 21 of the counter substrate 20 may be used. Further, the lower light-shielding film 12 also extends from the image display area to the periphery thereof and is connected to a constant potential source in the same manner as the capacitor line 18 in order to prevent the potential fluctuation from adversely affecting the TFT 30. Good.
[0057]
Further, in order to electrically connect the data line 6a and the source region 1d, a second intermediate conductive layer 15b formed of the same layer as the first intermediate conductive layer 15 is formed. The second intermediate conductive layer 15b is electrically connected to the source region 1d through a contact hole 24a penetrating the second interlayer insulating film 14 and the insulating film 2.
[0058]
A third interlayer insulating film 19 is disposed on the capacitor line 18, and a data line 6 a is stacked on the third interlayer insulating film 19. The data line 6a is electrically connected to the source region 1d through the contact hole 24b penetrating the third interlayer insulating film 19 and the dielectric film 17 and the second intermediate conductive layer 15b.
[0059]
A fourth interlayer insulating film 25 is formed on the third interlayer insulating film 19 and the data line 6a. The fourth interlayer insulating film 25 is planarized by a polishing process such as a CMP (Chemical Mechanical Polishing) process.
[0060]
A pixel electrode 9a is stacked on the data line 6a with a fourth interlayer insulating film 25 interposed therebetween. The pixel electrode 9 a is electrically connected to the first intermediate conductive layer 15 through a contact hole 26 b that penetrates the fourth interlayer insulating film 25, the third interlayer insulating film 19, and the dielectric film 17. The first intermediate conductive layer 15 is electrically connected to the drain region 1 e through a contact hole 26 a penetrating the second interlayer insulating film 14 and the insulating film 2. An alignment film 16 is laminated on the pixel electrode 9a and is subjected to an alignment process in a predetermined direction.
[0061]
When the ON signal is supplied to the scanning line 3a (gate electrode), the channel region 1a 'becomes conductive, the source region 1d and the drain region 1e are connected, and the image signal supplied to the data line 6a is a pixel. It is given to the electrode 9a.
[0062]
On the other hand, the counter substrate 20 is provided with a first light-shielding film 23 in a region facing the formation region of the data lines 6a, the scanning lines 3a, and the TFTs 30 of the element substrate, that is, a non-display region (non-opening region) of each pixel. Yes. The first light shielding film 23 prevents incident light from the counter substrate 20 side from entering the channel region 1 a ′, the source region 1 d, and the drain region 1 e of the TFT 30. A counter electrode (common electrode) 21 is formed over the entire surface of the substrate 20 on the first light shielding film 23. An alignment film 22 is stacked on the counter electrode 21 and is aligned in a predetermined direction.
[0063]
The alignment treatment of the alignment films 16 and 22 is to perform anisotropic etching on the porous film.
[0064]
A liquid crystal 50 is sealed between the element substrate 10 and the counter substrate 20. The TFT 30 writes an image signal supplied from the data line 6a to the pixel electrode 9a at a predetermined timing. Depending on the potential difference between the written pixel electrode 9a and the counter electrode 21, the orientation and order of the molecular assembly of the liquid crystal 50 change, and the light is modulated to enable gradation display.
[0065]
As shown in FIGS. 2 and 3, the counter substrate 20 is provided with a light shielding film 42 as a frame for partitioning the display area. The light shielding film 42 is formed of, for example, the same or different light shielding material as the light shielding film 23.
[0066]
A sealing material 41 that encloses liquid crystal in a region outside the light shielding film 42 is formed between the element substrate 10 and the counter substrate 20. The sealing material 41 is disposed so as to substantially match the contour shape of the counter substrate 20, and fixes the element substrate 10 and the counter substrate 20 to each other. The sealing material 41 is missing in a part of one side of the element substrate 10, and a liquid crystal injection port 78 for injecting the liquid crystal 50 is formed in the gap between the bonded element substrate 10 and the counter substrate 20. The After the liquid crystal is injected from the liquid crystal injection port 78, the liquid crystal injection port 78 is sealed with a sealing material 79.
[0067]
A data line driving circuit 61 and a mounting terminal 62 are provided along one side of the element substrate 10 in a region outside the sealing material 41 of the element substrate 10, and scanning lines are provided along two sides adjacent to the one side. A drive circuit 63 is provided. On the remaining side of the element substrate 10, a plurality of wirings 64 for connecting the scanning line driving circuits 63 provided on both sides of the screen display area are provided. In addition, a conductive material 65 for electrically connecting the element substrate 10 and the counter substrate 20 is provided in at least one corner of the counter substrate 20.
[0068]
Next, an alignment process in the present embodiment will be described with reference to FIGS. FIG. 1 schematically shows an image of orientation processing in the present embodiment, FIG. 6 shows a panel assembly process, and FIG. 7 shows the orientation processing process in FIG.
[0069]
In the assembly process, first, in steps S1 and S5 of FIG. 6, the element substrate 10 formed up to the pixel electrode 9a and the counter substrate 20 formed up to the counter electrode 21 are prepared. In the next steps S2 and S6, an alignment process is performed on the element substrate 10 and the counter substrate 20, respectively.
[0070]
That is, first, in step S21 of FIG. 7, a porous film is formed. FIG. 1 schematically shows a cross section of the alignment films 16 and 22. The alignment films 16 and 22 are constituted by a porous film 81. The porous film 81 has many holes 82 on the surface. The porous film 81 has a porosity (ratio of the pores 82 to the cross-sectional area) of 20 to 70%, and the diameter of each pore 82 is 1 nm to 50 nm. As a method for forming the porous film 81, there are a vapor deposition process, a sputtering process, a sol-gel method, a plasma CVD method, a laser ablation method, and the like, as will be described later.
[0071]
In the next step S22, the porous film 81 is subjected to surface modification by anisotropic etching. In this case, anisotropic etching is performed by tilting the pores 82 of the porous film 81 by a predetermined angle. By the anisotropic etching, the cut portion 83 is further formed in the hole 82 portion, the hole 82 spreads in an oblique direction, and a hole 84 that is inclined obliquely with respect to the surface of the porous film 81 as a whole is formed. . The pretilt angle can be expressed by the holes 84 inclined obliquely. As described later, anisotropic etching includes a method using an ion beam and a method using plasma.
[0072]
In the present embodiment, a desired pretilt angle can be expressed by the formation state of the pores 82 of the porous film 81, the angle and strength of anisotropic etching, and the like. As the porous film 81, not only an organic film such as polyimide, but also an inorganic film can be adopted, and even in this case, an arbitrary pretilt angle can be expressed.
[0073]
In the assembly process shown in FIG. 6, after such an alignment process is completed, a sealing material 41 and a conductive material 65 (see FIG. 2) are formed on the element substrate 10 (step S3). After the sealing material 41 is formed, the element substrate 10 and the counter substrate 20 are bonded together (step S10), and are pressed while performing alignment (step S11), and the sealing material 41 is cured. Finally, liquid crystal is sealed from a notch provided in a part of the seal material 41, and the notch is closed to seal the liquid crystal (step S12).
[0074]
Next, a specific method for forming the alignment films 16 and 22 will be described with reference to FIGS. FIG. 8 shows a combination example of porous film formation by the sol-gel method and anisotropic etching by ion beam irradiation.
[0075]
In step S31 of FIG. 8, a sol-gel method is employed to form a porous film. There are various methods for forming a porous film by the sol-gel method. The method for forming a porous film by the sol-gel method is a method for forming a film by utilizing a sol-gel reaction in which a colloidal material in which particles called sol are dispersed in a liquid is used as an intermediate to change to a solid gel. For example, in JP-A-7-257918, a coating solution of a silica precursor which is a sol is once prepared and subsequently applied onto a substrate by spray coating, dip coating or spin coating, and a thin film having a thickness of several microns or less. Form. And the technique which obtains the silica xerogel which is a porous film | membrane by gelatinizing this thin film, making it into silica, and drying is disclosed.
[0076]
In addition, in US Pat. No. 5,807,607 and US Pat. No. 5,900,909, as an example of forming a silica xerogel thin film, when a silica precursor that is a sol is used as a coating solution, glycerol or the like is contained in the solution at the time of preparation. There is also disclosed a method for improving the mechanical strength of a porous body by controlling the pore size and pore size distribution of silica xerogel obtained through subsequent gelation and solvent removal by containing the specific solvent.
[0077]
Further, according to the porous film forming method described in Japanese Patent Application Laid-Open No. 2001-122611, an example in which an organic polymer is used instead of a low boiling point solvent is disclosed. Then, the silica / organic polymer composite (hybrid) thin film is obtained by forming the coating liquid into a thin film and gelling the silica sol in the obtained thin film at 50 to 300 ° C. In this proposal, even when the organic polymer moves from sol to gel at 50 to 300 ° C., it remains in the reaction system substantially, so that the sol particles remain in a swollen state and become a gel body while maintaining their size and form. In the subsequent process, when the organic polymer is removed from the hybrid body to form a porous body, the porosity can be sufficiently increased.
[0078]
Thus, the porous film 81 having the pores 82 shown by the broken line in FIG. 1 is formed. Next, the porous film 81 formed by such a sol-gel method is irradiated with an ion beam such as argon (Ar) ions at a predetermined angle with respect to the surface of the film 81 (step S32). . For example, the surface modification of the porous film 81 can be performed by irradiating an ion beam with an intensity of several eV to several tens keV. In particular, effective sputtering is possible by irradiating an ion beam in an intensity range of several hundred eV to several tens keV. Thus, the pores 82 of the porous film 81 become the pores 84 that are inclined at a predetermined angle with respect to the surface of the membrane 81.
[0079]
JP-A-7-288247 discloses an etching method using an ion beam as a deep vertical dry etching method for silicon oxide. Japanese Patent Laid-Open No. 6-130391 discloses an alignment process by ion beam irradiation. The ion beam irradiation in this embodiment can be performed using these known techniques.
[0080]
In the liquid crystal 50 sealed between the element substrate 10 and the counter substrate 20, the orientation of the major axis of the liquid crystal molecules when no voltage is applied is defined by the alignment films 16 and 22. In this case, since the alignment films 16 and 22 are formed by subjecting the porous film 81 to anisotropic etching, the liquid crystal molecules can be set to a sufficiently high pretilt angle. As the porous film 81, either an organic film or an inorganic film can be employed.
[0081]
As described above, there are various methods for producing a porous membrane. FIG. 9 shows an example in which a porous film is formed by sputtering.
[0082]
In this case, the porous film 81 is formed by the sputtering process in step S35 of FIG. By appropriately setting various processing conditions such as the gas conditions, the substrate temperature, the film forming rate, and the degree of vacuum during the sputtering process, the density of the film to be formed can be increased. By performing ion beam irradiation similar to step S32 of FIG. 8 in step S36, the holes 84 inclined by a predetermined angle can be formed.
[0083]
FIG. 10 shows an example in which a porous film is formed by vapor deposition.
[0084]
In this case, the porous film 81 is formed by vapor deposition in step S38 of FIG. Basically, the film obtained by the vapor deposition process is a porous film. By forming the film by inclining the substrate at a predetermined angle with respect to the vapor deposition source, the diameter of the holes 82 can be increased. Further, by appropriately setting various processing conditions such as temperature and time, the holes 82 having a desired porosity and diameter can be formed. In step S39, by performing ion beam irradiation similar to that in step S32 of FIG. 8, the holes 84 inclined by a predetermined angle can be formed.
[0085]
In this embodiment, as a method for forming a porous film, for example, a method by plasma CVD disclosed in Japanese Patent Laid-Open No. 2000-216153 or a laser ablation disclosed in Japanese Patent Laid-Open No. 2002-093801 is used. Various methods such as the method used can be employed.
[0086]
Further, as described above, a method using plasma can be adopted as the anisotropic etching.
[0087]
For example, for plasma etching on SiO2, the document "Peter H.," Dry etching of SiO2 and Si3N4 ", Semiconductor International, (May 1986), pages 98 to 163 (Peter H. Singer; Dry Etching of SiO2 and Si3N4, SEMICONDUCTOR INTERNATIONAL, (MAY-1986), PP98-163) ". In this document, if a material such as SiO 2 is used, an etching gas such as C 3 F 8 containing a C component such as C 3 F 8 or a CF gas containing H such as CHF 3 is used during etching. Increases the selectivity with the underlying Si by causing CF-based deposition to suppress the etching of the underlying Si or reducing the active species that etch Si by promoting the reaction of H and F radicals. Thus, there is a description that etching is possible.
[0088]
For example, the porous film 81 is formed of SiO2, and the plasma etching technique disclosed in this document is employed in place of the steps S32, S36, and S39 of FIGS. A membrane can be obtained.
[0089]
As described above, in the present embodiment, by performing anisotropic etching in a direction inclined by a predetermined angle on the surface of the porous film, a pretilt angle of a predetermined angle can be expressed. In this case, by appropriately setting the pore diameter and porosity of the porous membrane, the material of the porous membrane, the anisotropic etching conditions, etc., the pretilt angle of an arbitrary angle including a relatively high angle can be set. It can be expressed. Further, as the porous film, not only an organic film but also an inorganic film can be employed, and an alignment film that exhibits excellent reliability and exhibits a desired pretilt angle can be configured. In this embodiment mode, alignment treatment can be performed in a non-contact state on the substrate surface, and dust and contamination can be prevented from being generated.
[0090]
Note that in this embodiment, an example in which the pixel electrode is applied to a flattened liquid crystal device has been described. However, it is obvious that the present invention can be similarly applied to a liquid crystal device that is not flattened. In addition, the alignment films on both the element substrate and the counter substrate do not necessarily have to be formed by the same manufacturing method, and may be manufactured by different manufacturing methods including rubbing treatment.
[0091]
Further, it is apparent that this embodiment can be applied to both horizontal alignment and vertical alignment.
[0092]
(Electronics)
Next, an overall configuration, particularly an optical configuration, of an embodiment of a projection color display device as an example of an electronic apparatus using the liquid crystal device described in detail as a light valve will be described. FIG. 11 is an explanatory diagram of a projection type color display device.
[0093]
In FIG. 11, a liquid crystal projector 1100, which is an example of a projection type color display device according to the present embodiment, prepares three liquid crystal modules including a liquid crystal device having a drive circuit mounted on a TFT array substrate, and each has RGB light bulbs 100R. , 100G and 100B. In the liquid crystal projector 1100, when projection light is emitted from a lamp unit 1102 of a white light source such as a metal halide lamp, light components R, G, and R corresponding to the three primary colors of RGB are obtained by three mirrors 1106 and two dichroic mirrors 1108. Divided into B, the light valves are guided to the light valves 100R, 100G and 100B corresponding to the respective colors. At this time, in particular, the B light is guided through a relay lens system 1121 including an incident lens 1122, a relay lens 1123, and an exit lens 1124 in order to prevent light loss due to a long optical path. The light components corresponding to the three primary colors modulated by the light valves 100R, 100G, and 100B are synthesized again by the dichroic prism 1112 and then projected as a color image on the screen 1120 via the projection lens 1114.
[0094]
The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view for explaining an alignment film of a liquid crystal device according to an embodiment of the present invention.
FIG. 2 is a plan view of the liquid crystal device of the present embodiment as viewed from the counter substrate side together with the components formed thereon.
3 is a cross-sectional view of the liquid crystal device after being assembled at the end of the assembling process in which a TFT substrate, which is an active matrix substrate, and a counter substrate are bonded together to enclose liquid crystal, and cut along the line HH ′ in FIG.
FIG. 4 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels constituting a pixel region of the liquid crystal device of this embodiment.
FIG. 5 is a cross-sectional view showing in detail a pixel structure of the liquid crystal device of FIGS. 1 to 4;
FIG. 6 is a flowchart showing an assembly process of the liquid crystal device.
FIG. 7 is a flowchart showing alignment processing in the present embodiment.
FIG. 8 is a flowchart showing a specific example of orientation processing.
FIG. 9 is a flowchart showing a specific example of orientation processing.
FIG. 10 is a flowchart showing a specific example of orientation processing.
FIG. 11 is an explanatory diagram of a projection type color display device.
[Explanation of symbols]
16, 22 ... Alignment film, 81 ... Porous film, 82, 84 ... Pore.

Claims (11)

First and second liquid crystal substrates disposed opposite to each other;
Liquid crystal sandwiched between the first and second liquid crystal substrates;
A liquid crystal device comprising: an alignment film formed of an alignment-treated porous film and provided on at least one of the first and second liquid crystal substrates so as to be in contact with the liquid crystal. The alignment film is characterized in that the liquid crystal molecules exhibit a desired pretilt angle by changing the porosity and diameter of the porous film and at least one of the conditions of the alignment treatment. The liquid crystal device according to claim 1. 2. The liquid crystal device according to claim 1, wherein the porous film has a porosity of 20 to 70% and a diameter of each pore is 1 nm to 50 nm. The liquid crystal device according to claim 1, wherein the porous film is an inorganic film. The liquid crystal device according to claim 1, wherein the porous film is formed by any one of a sol-gel method, a sputtering method, a vapor deposition method, a plasma CVD method, and a laser ablation method. The liquid crystal device according to claim 1, wherein the alignment process is an anisotropic etching process. The liquid crystal device according to claim 6, wherein the alignment film is formed by subjecting the porous film to an anisotropic etching of either ion beam irradiation or plasma etching. Forming a porous film on at least one of the first and second liquid crystal substrates disposed to face each other;
And a step of forming an alignment film by subjecting the porous film to anisotropic etching. 9. The method of manufacturing a liquid crystal device according to claim 8, wherein the step of forming the porous film employs one of a sol-gel method, a sputtering method, a vapor deposition method, a plasma CVD method, and a laser ablation method. Method. 9. The method of manufacturing a liquid crystal device according to claim 8, wherein the step of forming the alignment film by performing anisotropic etching includes one of ion beam irradiation and plasma etching. A liquid crystal device according to any one of claims 1 to 7 or a liquid crystal device manufactured by the method for manufacturing a liquid crystal device according to any one of claims 8 to 10 is used. Electronic equipment.

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