JP2005202288A - Substrate for electrooptical device, its manufacturing method, and electrooptical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve display performance by flattening the surface asperities produced when forming a light shading film to flatten electrodes and an alignment film. <P>SOLUTION: A substrate of an electrooptical device has: a substrate 20 facing a substrate 10 on which switching elements are mounted; a patterned light shading film 23 formed on the above substrate 20; a film 83 with a flattened surface formed on the above substrate 20 which includes the light shading film 23; and the electrodes 21 formed on the above planarized film 83. The film is flattened by polishing a predetermined material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a substrate for an electro-optical device suitable for a liquid crystal panel or the like that modulates incident light according to an image signal, a manufacturing method thereof, and an electro-optical device.

  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), for example, are arranged in a matrix on one substrate, and a counter electrode is arranged on the other substrate and sealed between the two substrates. An image can be displayed by changing the optical characteristics of the liquid crystal layer according to the image signal.

  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.

  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. Then, the alignment film is rubbed.

Also, on the counter substrate side, so-called black is used to prevent display defects caused by light incident on the TFT element portion, decrease in contrast due to non-orientation regions generated by the TFT element structure, and color mixture of color materials. A light shielding film called a matrix is formed.
JP-A-6-27456

  By the way, the counter substrate is configured by forming the above-described light shielding film on a glass or quartz substrate, forming a counter electrode on the light shielding film, and further forming an alignment film on the counter electrode. The light shielding film is formed so as to face the wiring region and the TFT element forming region formed on the element substrate side, and prevents light from entering these regions. Due to the patterning of the light shielding film, the counter electrode has irregularities along the light shielding film forming region. Accordingly, the alignment film on the counter substrate side also has irregularities along the light shielding film. For this reason, the rubbing process with respect to the alignment film becomes non-uniform, and there is a problem that alignment failure may occur.

  Further, light incident from the counter substrate side passes through the quartz substrate, the counter electrode, and the alignment film and enters the liquid crystal layer. However, since the refractive index difference between the refractive index of the quartz substrate and the refractive index of ITO constituting the counter electrode is relatively large, there is a problem that reflection occurs at the interface between the quartz substrate and the counter substrate. . Note that the apparatus of Patent Document 1 is disclosed as a film formed between a quartz substrate and an ITO electrode.

  The present invention has been made in view of such problems, and provides a substrate for an electro-optical device, a method for manufacturing the same, and an electro-optical device that can improve display performance by enabling flattening of electrodes. For the purpose.

  An electro-optical device substrate according to the present invention includes an opposing substrate facing an element substrate on which a switching element is formed, a patterned light shielding film formed on the opposing substrate, and the light shielding film. And a planarization film having a planarized surface formed on the opposing substrate, and an electrode formed on the planarization film.

  According to such a configuration, the patterned light shielding film is formed on the opposite substrate. A planarizing film is formed on the substrate including the light shielding film. On the substrate including the light shielding film, the patterned light shielding film has irregularities. However, since the surface of the planarization film formed on the substrate including the light shielding film is planarized, the base of the electrode is planarized. Thereby, the electrode formed on the planarizing film is also planarized. Therefore, for example, when an alignment film or the like is formed on the electrode, the alignment film can be flattened, the rubbing can be made uniform, and the display performance can be improved.

  The electrode is a transparent electrode.

  According to such a configuration, since the electrode is transparent, light can be passed through the electrode and can be used in an electro-optical device.

  The planarizing film is a silicon nitride film.

  According to such a configuration, the silicon nitride film is interposed between the substrate and the electrode, and reflection of light incident on the electrode from the substrate can be suppressed. Thereby, it can contribute to the improvement of display performance.

  The planarizing film is a silicon oxide film.

  According to such a configuration, the base of the electrode can be flattened.

  The method for manufacturing a substrate for an electro-optical device according to the present invention includes a step of patterning and forming a light shielding film on a substrate opposite to an element substrate on which a switching element is formed, and on the substrate including the light shielding film. Forming a film of a predetermined material, flattening the film of the predetermined material, and forming an electrode on the flattened film of the predetermined material.

  According to such a configuration, a patterned light shielding film is formed on the opposite substrate. A planarized film of a predetermined material is formed on the substrate including the light shielding film. The flattened film of the predetermined material prevents unevenness due to the light-shielding film on the substrate from appearing on the surface. Thereby, the electrode on the film of the predetermined material is also flattened. For example, when an alignment film or the like is formed on the electrode, the alignment film can be flattened and the rubbing can be made uniform.

  The step of planarizing is characterized in that the film of the predetermined material is flattened by polishing the film of the predetermined material.

  According to such a configuration, the base of the electrode is flattened by polishing the film of the predetermined material on the light shielding film.

  In the planarization step, a chemical mechanical polishing method is employed as the polishing process.

  According to such a structure, the film | membrane of the predetermined material on a light shielding film can be grind | polished easily and reliably.

  In the planarization step, the planarization is performed by removing the film of the predetermined material on the light shielding film formation region.

  According to such a configuration, a film of a predetermined material is formed on the light shielding film and between the light shielding films. Among these, a film of a predetermined material is removed on the alignment film formation region. The base of the electrode is flattened by the light shielding film and the film of the predetermined material.

  In the planarization step, the film of the predetermined material on the light shielding film forming region is removed by a self-alignment photolithography process using the light shielding film and an etching process.

  According to such a configuration, a film of a predetermined material is formed on the light shielding film and between the light shielding films. Among these, on the alignment film formation region, a film of a predetermined material is removed by self-alignment using a light shielding film. As a result, the alignment work for the mask and the light shielding film for removing the film of the predetermined material becomes unnecessary.

  The photolithography process uses a negative resist.

  According to such a configuration, since a negative resist is used, the film of the predetermined material can be removed by a self-alignment photolithography process and an etching process.

  An electro-optical device according to the present invention is configured using the electro-optical device substrate manufactured using the electro-optical device substrate or the electro-optical device substrate manufacturing method.

  According to such a configuration, since the electrode of the electro-optical device substrate is flattened, for example, when an alignment film is formed on the electrode, rubbing on the alignment film can be made uniform, and display Performance can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a cross section of an electro-optical device substrate according to a first embodiment of the present invention. In this embodiment, an electro-optical device substrate is applied to a counter substrate of a liquid crystal device. FIG. 2 is a plan view of an element substrate such as a TFT substrate as viewed from the counter substrate side together with each component formed on the element substrate. FIG. 3 shows a liquid crystal by bonding the element substrate and the counter substrate together. FIG. 3 is a cross-sectional view of the liquid crystal device after the assembly process for sealing is cut along the line HH ′ in FIG. 2. FIG. 4 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels constituting a pixel region of a liquid crystal device configured using the electro-optical device substrate according to the present embodiment. FIG. 5 is a process diagram illustrating a method of manufacturing the electro-optical device substrate of FIG. 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.

  First, an overall configuration of a liquid crystal device configured using a counter substrate which is a substrate for an electro-optical device according to the present embodiment will be described with reference to FIGS.

  As shown in FIGS. 2 and 3, the liquid crystal device includes, for example, a quartz substrate, a glass substrate, an element substrate 10 using a silicon substrate, and a counter substrate using, for example, a glass substrate or a quartz substrate. The liquid crystal 50 is sealed between the two. The element substrate 10 and the counter substrate 20 that are arranged to face each other are bonded together by a sealing material 41.

  On the element 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 element 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.

  FIG. 4 shows an equivalent circuit of elements on the element 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.

  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.

  A plurality of pixel electrodes 9a are provided in a matrix on the element substrate 10, and data lines 6a and scanning lines 3a are provided along the vertical and horizontal boundaries of the pixel electrodes 9a. 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 to face a channel region (not shown). That is, the pixel switching TFT 30 is configured by disposing the gate electrode and the channel region connected to the scanning line 3a so as to face each other at the intersection of the scanning line 3a and the data line 6a.

  In FIG. 1, the counter substrate 20 includes a first light-shielding film 23 that forms a so-called black matrix in a region facing the data line 6 a, the scanning line 3 a, and the TFT 30 formation region of the element substrate 10, that is, a non-display region of each pixel. Is formed. The first light shielding film 23 prevents incident light from the counter substrate 20 side from entering a channel region of the TFT 30 and a source region, drain region, etc. (not shown).

  In the present embodiment, a silicon nitride film 83 as a planarizing film is formed on the entire surface of the counter substrate 20 and the first light shielding film 23. The first light shielding film 23 is covered with the silicon nitride film 83, and the surface of the silicon nitride film 83 is planarized. A counter electrode (ITO) 21 is formed on the entire surface of the substrate 20 on the silicon nitride film 83.

  As shown in FIG. 3, an alignment film 22 made of a polyimide-based polymer resin is laminated on the counter electrode 21, and is rubbed in a predetermined direction. 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. The alignment state of the molecular assembly of the liquid crystal 50 changes according to the written potential difference between the pixel electrode 9a and the counter electrode 21 to modulate light and enable gradation display.

  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.

  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. Liquid crystal is injected from a liquid crystal injection port 78 into the gap between the element substrate 10 and the counter substrate 20 that are bonded together. After the liquid crystal injection, the liquid crystal injection port 78 is sealed with a sealing material 79.

  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 are provided for connecting between the scanning line driving circuits 63 provided on both sides of the screen display area. 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.

  Next, the panel assembly process will be described. The element substrate 10 (TFT substrate) and the counter substrate 20 are manufactured separately. Polyimide to be the alignment films 16 and 22 is applied to the element substrate 10 and the counter substrate 20 on which the electrodes 9a and 21 made of ITO are formed. Next, a rubbing process is performed on the alignment film 16 on the surface of the element substrate 10 and the alignment film 22 on the surface of the counter substrate 20.

  Next, a cleaning process is performed. This cleaning process is for removing dust generated by the rubbing process. When the cleaning process is completed, the sealing material 41 and the conductive material 65 (see FIG. 2) are formed on the element substrate 10 or the counter substrate 20. After the sealing material 41 is formed, next, the element substrate 10 and the counter substrate 20 are bonded to each other, and the sealing material 41 is cured by performing pressure bonding while performing alignment. Finally, liquid crystal is sealed from a notch (liquid crystal injection port 78) provided in a part of the sealing material 41, and the notch is closed by the sealing material 79 to seal the liquid crystal.

  In the embodiment configured as described above, the counter substrate 20 has a planarized silicon nitride film 83 formed between the substrate 20 and the counter electrode 21. By the planarized silicon nitride film 83, the counter electrode 21 on the silicon nitride film 83 is also formed flat. Furthermore, the alignment film 22 on the counter electrode 21 is also formed flat. Therefore, in the rubbing process for the alignment film 22, uniform rubbing is performed over the entire surface of the substrate 20, and the occurrence of alignment failure is prevented.

  The refractive index of the silicon nitride film 83 is 1.8 to 2.0. That is, a material having a refractive index intermediate between the refractive index of the substrate 20 made of quartz or the like and the refractive index of the counter electrode 21 made of ITO is interposed between the substrate 20 and the counter electrode 21. This prevents light incident from the counter substrate 20 side from being reflected at the interface between the substrate 20 and the counter electrode 21.

  Next, the manufacturing method of the embodiment configured as described above will be described with reference to the process diagram of FIG. FIG. 5 shows a counter substrate process.

  A light shielding film material is formed on the entire surface of the prepared glass or quartz substrate 20. Next, the light shielding film material is patterned by photolithography and etching. FIG. 5A shows the patterned first light shielding film 23. The film thickness of the first light shielding film 23 is set to 100 nm, for example.

  Next, a silicon nitride material 83 ′ is formed on the substrate 20 and the light shielding film 23. The silicon nitride material 83 'is formed with a film thickness of 150 nm, for example. Thereby, the light shielding film 23 is reliably covered with the silicon nitride material 83 '(FIG. 5B). For example, a material having a refractive index of 1.8 to 2.0 is used as the silicon nitride material 83 '.

  Next, the silicon nitride material 83 ′ is flattened by a polishing process such as a CMP (Chemical Mechanical Polishing) process. FIG. 5C shows the planarized silicon nitride film 83. Next, a transparent conductive film such as an ITO film is deposited on the silicon nitride film 83 over the entire area of the substrate 20 by sputtering or the like to a thickness of about 140 nm, for example, to form the counter electrode 21 ( FIG. 5 (d)).

  As described above, in this embodiment, the counter electrode is planarized by forming the planarized silicon nitride film on the substrate and the light shielding film as the base of the counter electrode. Thereby, the alignment film formed on the counter electrode can be flattened, and uniform rubbing can be performed over the entire surface of the substrate, thereby preventing the occurrence of alignment failure.

  Moreover, since a silicon nitride film having a refractive index of 1.8 to 2.0 is formed between the substrate and the counter electrode made of ITO, reflection of light incident on the counter electrode is prevented. There is also an effect that can be done.

  Note that although a silicon nitride film is formed between the counter substrate and the counter electrode, the base of the counter electrode may be planarized in order to prevent alignment failure, and a film other than the silicon nitride film may be formed. For example, a planarized silicon oxide film may be formed between the counter substrate and the counter electrode. In this case, an antireflection function cannot be obtained, but an orientation failure prevention function can be obtained.

  Incidentally, in the manufacturing method shown in FIG. 5, the silicon nitride material is planarized by a polishing process such as CMP. On the other hand, planarization films such as a silicon nitride film and a silicon oxide film can be formed by photolithography and etching.

  FIG. 6 is a process diagram showing a method for manufacturing a substrate for an electro-optical device according to the second embodiment of the invention, and shows an example in which planarization is performed by photolithography and etching. In FIG. 6, the same components as those in FIG.

  A light shielding film material is formed on the entire surface of the prepared glass or quartz substrate 20 and patterned to form a first light shielding film 23 shown in FIG. Next, a silicon nitride material 93 ′ is formed on the substrate 20 and the light shielding film 23. In this case, the film thickness of the silicon nitride material 93 ′ is set to be approximately the same as the film thickness of the light shielding film 23 (FIG. 6B).

  Next, as shown in FIG. 6C, a resist 90 is formed on the entire surface of the silicon nitride material 93 '. The resist 90 is a positive resist. Next, the resist 90 is exposed using a mask 91 having an opening corresponding to the first light shielding film 23 formation region. Thus, the resist 90 is left only in the portion corresponding to the region other than the region where the light shielding film 23 is formed (FIG. 6D).

  Next, the silicon nitride material 93 ′ is etched to remove the silicon nitride material 93 ′ on the light shielding film 23 formation region, and the resist 90 is peeled off. Thus, as shown in FIG. 6E, a silicon nitride film 93 as a planarizing film having a film thickness substantially the same as that of the light shielding film 23 is formed in a region other than the light shielding film 23 forming region. Finally, as shown in FIG. 6F, the counter electrode 21 is formed on the light shielding film 23 and the silicon nitride film 93.

  As described above, the base of the counter electrode can be planarized also by photolithography and etching.

  Further, in the case of using photolithography and etching, the base of the counter electrode can be flattened by photolithography and etching by self-alignment using the light shielding film 23.

  FIG. 7 is a process diagram illustrating a method for manufacturing an electro-optical device substrate according to a third embodiment of the present invention, and illustrates an example in which planarization is performed by self-alignment. In FIG. 7, the same components as those in FIG. Note that FIG. 7 shows the up and down directions opposite to those in FIGS. 5 and 6.

  A light shielding film material is formed on the entire surface of the prepared glass or quartz substrate 20 and patterned to form a first light shielding film 23 shown in FIG. Next, a silicon nitride material 93 ′ is formed on the substrate 20 and the light shielding film 23. In this case, the film thickness of the silicon nitride material 93 ′ is set to be approximately the same as the film thickness of the light shielding film 23 (FIG. 6B).

  Next, as shown in FIG. 7C, a resist 95 is formed on the entire surface of the silicon nitride material 93 '. The resist 95 is a negative resist. Next, the resist 95 is exposed by self-alignment using the light shielding film 23. In addition, the arrow of FIG. 7 has shown the irradiation direction at the time of exposure. Thereby, the resist 95 is left only in the portion corresponding to the region other than the region where the light shielding film 23 is formed (FIG. 7D).

  Next, the silicon nitride material 93 ′ is etched to remove the resist 90. In this way, as shown in FIG. 7E, a silicon nitride film 93 having substantially the same thickness as the light shielding film 23 is left in a region other than the region where the light shielding film 23 is formed. Finally, as shown in FIG. 7F, the counter electrode 21 is formed on the light shielding film 23 and the silicon nitride film 93.

  As described above, in the example of FIG. 7, photolithography and etching processes are performed by self-alignment using the light-shielding film 23, and the mask formation step can be omitted compared to the example of FIG.

  6 and 7, it is apparent that a silicon oxide film may be employed instead of the silicon nitride film.

  The electro-optical device of the present invention is not limited to a passive matrix type liquid crystal display panel but an active matrix type liquid crystal panel (for example, a liquid crystal display panel including a TFT (thin film transistor) or a TFD (thin film diode) as a switching element). It is possible to apply to the same. In addition to liquid crystal display panels, various devices such as electroluminescence devices, organic electroluminescence devices, plasma display devices, electrophoretic display devices, and devices using electron emission (Field Emission Display and Surface-Conduction Electron-Emitter Display, etc.) The present invention can be similarly applied to the electro-optical device.

FIG. 3 is a cross-sectional view schematically showing a cross section of the electro-optical device substrate according to the first embodiment of the invention. The top view which looked at element substrates, such as a TFT substrate, from the counter substrate side of this Embodiment with each component formed on it. FIG. 3 is a cross-sectional view of the liquid crystal device after the assembly process in which the element substrate and the counter substrate are bonded to each other and the liquid crystal is sealed is cut along the line HH ′ in FIG. 2. FIG. 6 is an equivalent circuit diagram of various elements, wirings, and the like in a plurality of pixels constituting a pixel region of a liquid crystal device configured using the electro-optical device substrate of the present embodiment. Process drawing which shows the manufacturing method of the board | substrate for electro-optical devices of FIG. 1 in process order. FIG. 9 is a process diagram showing a method for manufacturing a substrate for an electro-optical device according to a second embodiment of the invention. FIG. 9 is a process diagram showing a method for manufacturing a substrate for an electro-optical device according to a third embodiment of the invention.

Explanation of symbols

    20 ... counter substrate, 21 ... counter electrode, 23 ... light shielding film, 83 ... silicon nitride film.

Claims (11)

An opposing substrate facing the element substrate on which the switching element is formed;
A patterned light-shielding film formed on the substrate;
A planarization film formed on the substrate including the light shielding film and having a planarized surface;
An electro-optical device substrate comprising an electrode formed on the planarizing film.   The substrate for an electro-optical device according to claim 1, wherein the electrode is a transparent electrode.   3. The electro-optical device substrate according to claim 1, wherein the planarizing film is a silicon nitride film.   3. The electro-optical device substrate according to claim 1, wherein the planarizing film is a silicon oxide film. A step of patterning and forming a light shielding film on a substrate on the opposite side opposite to the element substrate on which the switching element is formed;
Forming a film of a predetermined material on the substrate including the light shielding film;
Planarizing the film of the predetermined material;
And a step of forming an electrode on the flattened film of the predetermined material.   6. The method for manufacturing a substrate for an electro-optical device according to claim 5, wherein in the planarizing step, the film of the predetermined material is planarized by polishing the film of the predetermined material.   The method for manufacturing a substrate for an electro-optical device according to claim 6, wherein the planarizing step employs a chemical mechanical polishing method as the polishing process.   6. The method of manufacturing a substrate for an electro-optical device according to claim 5, wherein the planarizing step performs planarization by removing the film of the predetermined material on the light shielding film forming region.   9. The flattening step includes removing the film of the predetermined material on the light shielding film formation region by a self-alignment photolithography process using the light shielding film and an etching process. A method for manufacturing a substrate for an electro-optical device.   The method for manufacturing a substrate for an electro-optical device according to claim 9, wherein a negative resist is used in the photolithography process.   An electro-optical device manufactured using the electro-optical device substrate according to any one of claims 1 to 4 or the electro-optical device substrate manufacturing method according to any one of claims 5 to 10. An electro-optical device comprising a substrate for use.

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