JP3214198B2 - Method for manufacturing active matrix display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an active matrix display device. More specifically, the present invention relates to a method for forming a black mask used for optical pixel separation.

[0002]

2. Description of the Related Art In general, an active matrix display device has a flat panel structure composed of a pair of a driving substrate and an opposing substrate joined through a predetermined gap and an electro-optical material such as a liquid crystal held in the gap. I have. The drive board includes
A matrix of pixel electrodes and switching elements for driving each pixel electrode are formed. On the counter substrate, a color filter or the like matched to the counter electrode and each pixel electrode is formed. In addition, a black mask is formed to optically separate the individual pixel electrodes formed on the driving substrate side. It is necessary to precisely match the pattern of the black mask with the pattern of the pixel electrode. However, there is a mechanical limit to the alignment accuracy. For this reason, the size of the pixel electrode opening provided on the driving substrate must be designed in consideration of the positional deviation from the counter substrate, and a certain margin is required. When the arrangement pitch of the pixel electrodes is reduced along with the high definition of the display device, the ratio of the margin to this pitch becomes very large, and the aperture ratio is reduced.

Therefore, a structure (on-chip black) in which a black mask is provided on the drive substrate side has been developed in order to ease the relative positioning accuracy between the opposing substrate and the drive substrate. FIG. 6 shows an example of a conventional method for manufacturing on-chip black, in which a black mask is formed first and a pixel electrode is formed thereafter. First, in step A, the substrate 10
A light-shielding film 102 is formed on 1. Resist 10 in step B
3 is patterned into a predetermined shape. Resist 1 in process C
The black mask 104 is formed by etching the light-shielding film 102 through the layer 03. In step D, the resist 103 is peeled off. In step E, a transparent conductive film 105 is formed. In step F, the resist 106 is patterned into a predetermined shape. In step G, the transparent conductive film is etched through the resist 106 to form the pixel electrode 107. Finally, in step H, the resist 106 is removed. Thus, the black mask 104 and the pixel electrode 107 are provided on the substrate 101.

FIG. 7 is a process diagram showing another conventional method for forming on-chip black, in which a pixel electrode is formed first, and then a black mask is formed. In step A, a transparent conductive film 202 is formed on the substrate 201. Resist 20 in step B
3 is patterned in a matrix. In step C, the transparent conductive film is etched through the resist 203 to form the pixel electrode 20.
4 is formed. In step D, the resist 203 is stripped. In step E, a light-shielding film 205 is formed. Resist 20 in step F
6 is patterned along the boundary of the pixel electrode 204. In step G, the light-shielding film 205 is etched through the resist 206 to form a black mask 207. Finally, in step H, the resist 206 is removed. In this manner, the pixel electrode 204 and the black mask 2 bordering the pixel electrode 204 are formed on the substrate 201.
07 can be formed.

FIG. 8 is a process chart showing still another conventional method for forming on-chip black. In this example, a black mask is formed first, and then a pixel electrode is provided via an interlayer insulating film. In step A, the light shielding film 302 is formed on the substrate 301.
To form In step B, the resist 303 is patterned into a predetermined shape by photolithography. In step C, the light shielding film 302 is etched via the resist 303 to be processed into a black mask 304. The resist 303 used in the process D is removed. In step E, interlayer insulating film 305
Is coated. In step F, a transparent conductive film 306 is formed to overlap. In step G, the resist 307 is patterned in a matrix. In step H, the transparent conductive film is etched through the resist 307 to be processed into the pixel electrode 308. Finally, process I
The used resist 307 is peeled off. Accordingly, the black mask 304 and the pixel electrode 308 which are electrically separated from each other by the interlayer insulating film 305 are provided on the substrate 301. Note that electrical isolation is required when a metal material is used for the light-shielding film.

FIG. 9 is a process chart showing still another conventional method for forming on-chip black. Unlike the conventional example shown in FIG. 8, a pixel electrode is formed first, and then a black mask is provided. In step A, a transparent conductive film 402 is formed on the substrate 401. In step B, the resist 403 is patterned in a matrix by photolithography. In step C, the transparent conductive film is etched through the resist 403 to be processed into the pixel electrode 404. Resist 40 not required in step D
3 is peeled off. In step E, the interlayer insulating film 405 is covered.
In step F, a light-shielding film 406 is formed to overlap. In step G, the resist 407 is patterned along the gap between the pixel electrodes 404. In step H, the light-shielding film 406 is etched through the resist 407 to be processed into a black mask 408. Finally, the resist 407 used in the step I is peeled off. As a result, a pixel electrode 404 electrically insulated from each other by an interlayer insulating film 405 and a black mask 408 bordering the pixel electrode 404 are formed on the substrate 401.

[0007]

In the conventional on-chip black structure shown in FIGS. 6 and 7, the black mask and the pixel electrode are located on the same layer in the layer structure. With the same layer structure, the substrate surface can be made relatively flat, which is advantageous for controlling the alignment of liquid crystal. However, in order to form the same layer structure, it is necessary that, for example, the black mask 104 is not affected by the etching solution used for the processing of the pixel electrode 107 in the process G of FIG. Also in the process G shown in FIG. 7, it is necessary that the previously formed pixel electrode 204 is not affected by the etching solution used for processing the black mask 207. However, in practice, such an etching process is extremely difficult. Therefore, it is necessary to interpose an interlayer insulating film as in the method shown in FIGS. 8 and 9, but there is a problem that the manufacturing process is complicated and the number of steps is increased. When the transparent conductive film 306 is etched on the interlayer insulating film 305 as shown in Steps G and H in FIG. 8, irregularities corresponding to the respective film thicknesses occur in the portion where the pixel electrode 308 and the black mask 304 are adjacent. it can. Therefore, it is difficult to perform precise patterning with the edge of the black mask and the edge of the pixel electrode extremely close to each other. Similarly, as shown in steps G and H in FIG. 9, the black mask 40 is formed by interposing an interlayer insulating film 405.
8 and the pixel electrode 404 have irregularities or steps, making precise etching difficult. 6 to 9
In each of the conventional methods described in (1) and (2), patterning of the resist is performed twice, and it is necessary to align two photomasks, which complicates the process.

As described above, in the conventional method, when a black mask and a pixel electrode are formed on the same layer, selectivity in etching a light shielding film material and a transparent conductive film material is a serious problem. Therefore, it is difficult to form a black mask and a pixel electrode on the same layer.
Further, if an interlayer insulating film is interposed between the pixel electrode and the black mask, the interlayer insulating film swells near the edge of the black mask, so that it is difficult to precisely match the edge of the pixel electrode. Further, in the conventional on-chip black forming method, the light-shielding film is patterned using a photomask dedicated to the black mask separately from the pixel electrodes. For this reason, a photolithography step and an etching step are added in addition to the patterning of the pixel electrode, so that the number of steps is increased and an extra mask cost is required, which is disadvantageous in cost.

[0009]

The following means have been taken in order to solve the above-mentioned problems of the prior art. The present invention is applied to a method for manufacturing an active matrix display device having an on-chip black structure. This active matrix display device has a flat panel structure in which a drive substrate and a counter substrate are joined to each other, and an electro-optical material such as liquid crystal is held between the two substrates. On the drive substrate, a matrix of pixel electrodes, a black mask bordering each pixel electrode, and a switching element for driving each pixel electrode are formed. On the other hand, the counter substrate is provided with at least a counter electrode. An active matrix display device having such a configuration is manufactured by the following steps. First, a film forming step of forming a transparent conductive film on a driving substrate provided with switching elements in advance is performed. Next, a patterning step of etching the transparent conductive film through a resist patterned in a matrix and processing the transparent conductive film into a pixel electrode is performed. Subsequently, a black mask forming step of forming a black mask by self-alignment through the remaining resist is performed. Finally,
A lift-off step for removing the resist is performed. The par
In the tanning step, the transparent conductive film is over-etched
An undercut is provided below the resist edge. This place
In the black mask forming step, the undercut
Black mask in a state separated from each pixel electrode via
To form

In addition, the above-mentioned problems of the prior art are solved.
Therefore, the following measures were taken. The present invention uses an on-chip black structure.
Of the active matrix display device
It is. This active matrix display device is
The opposing substrates are joined together and electric light such as liquid crystal is
It has a flat panel structure holding chemical substances. Drive
Matrix pixel electrodes and individual pixel electrodes
A switch for driving the black mask and each pixel electrode
A chining element is formed. On the other hand, there is little
Both are provided with a counter electrode. With this configuration,
Active matrix display devices are manufactured by the following processes.
It is. First, a driving base provided with a switching element in advance
A film forming step of forming a transparent conductive film on the plate is performed. Next
Through a resist patterned in a matrix
A pattern that etches the transparent conductive film and processes it into a pixel electrode
Perform the aging process. Then, through the remaining resist
To form a black mask by self-alignment
A black mask forming step is performed. Finally, the resist
A lift-off process for removing the metal. In the black mask forming step, a light-shielding region is selectively formed on the base surface from which the transparent conductive film has been removed by etching by applying an ion implantation method.

[0011]

According to the present invention, after patterning the pixel electrode, a light-shielding film is formed by a vapor deposition method, a sputtering method, a CVD method or the like without removing the resist, and a black mask is obtained by self-alignment. Thereafter, a so-called lift-off method of removing the unnecessary light-shielding film by removing the resist is adopted. As a result, a black mask can be formed on the drive substrate by self-alignment, and the alignment accuracy between the black mask and the pixel electrode can be significantly improved, and the number of steps can be significantly reduced. Also, by over-etching the pixel electrode, electrical separation between the pixel electrode and the black mask can be easily realized. Therefore, a conductive material such as a metal can be used as the light-shielding film, and the degree of freedom in material selection is increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic partial sectional view showing a finished state of an active matrix display device manufactured according to the present invention. As shown, the active matrix display device has a flat panel structure in which a driving substrate 1 and a counter substrate 2 are joined via a predetermined gap. A liquid crystal 3 is held between the driving substrate 1 and the counter substrate 2 as an electro-optical material. A counter electrode 4 is formed on the inner surface of the counter substrate 2. On the other hand, on the inner surface of the drive substrate 1, a matrix of pixel electrodes 5, a black mask 6 surrounding each pixel electrode 5, and a switching element 7 for driving each pixel electrode 5 are formed. In this example, the switching element 7 is formed of a thin film transistor formed on an insulating substrate 8. The thin film transistor includes a semiconductor thin film 9 patterned in a predetermined shape and a gate electrode G formed on the semiconductor thin film 9 with an insulating film 10 interposed therebetween. A source region S and a drain region D are formed in the semiconductor thin film 9. The thin film transistor having such a configuration is covered with the first interlayer insulating film 11. A wiring electrode 12 electrically connected to the source region S of the thin film transistor is formed thereon. A flattening film 14 is formed on the first interlayer insulating film 11 with a second interlayer insulating film 13 interposed. In this example, the pixel electrode 5 and the black mask 6 are formed on the flattening film 14 as the same layer. Note that the flattening film 14 can be used as a color filter if it is colored in RGB ternary colors in conformity with each pixel electrode 5.

A feature of the present invention is that a black mask 6 is provided.
Are formed in a self-aligned relationship with the pixel electrode 5 by a lift-off method. Basically, a transparent conductive film is formed on the drive substrate 1 provided with the switching elements 7 in advance. Next, the transparent conductive film is etched through a resist patterned in a matrix to process the pixel electrode 5. Further, a black mask 6 is formed by self-alignment through the remaining resist. Finally, the resist is peeled off, and unnecessary portions of the black mask are removed by lift-off.

Next, a first embodiment of the black mask forming method according to the present invention will be described in detail with reference to FIG. First, in step A, a transparent conductive film 22 is entirely formed on a substrate 21. In this example, the substrate 2 is used for easy understanding.
Although FIG. 1 is simplified, actually, a switching element, an interlayer insulating film, and a flattening film are formed. However, the present invention is not limited to the configuration of the driving substrate shown in FIG. 1, and may have a structure in which a pixel electrode and a black mask are formed on an interlayer insulating film, for example. Further, as the transparent conductive film 22, for example, ITO can be used. Next, in step B, a resist 23 is applied on the transparent conductive film 22 and patterned in a matrix by photolithography. Further, in step C, the transparent conductive film 22 is wet-etched via the resist 23 to be processed into the pixel electrode 24. In this example, overetching is performed to remove the transparent conductive film larger than the opening of the resist 23. This makes the resist 2
An undercut 25 is provided at the lower part of the edge of the third. Next, in step D, a light-shielding film 26 is entirely formed. In this example, a conductive film material is selected, and a vapor deposition method, a sputtering method, a CV
The film is formed by a D method, a spray method, a coating method, or a printing method.
Finally, in step E, the resist 23 is stripped to remove an unnecessary light-shielding film, thereby forming a black mask 27. According to this method, it is possible to form the conductive black mask 27 by self-alignment while being separated from the pixel electrode 24 via the undercut 25.

FIG. 3 is a process chart showing a second embodiment of the black mask forming method according to the present invention. Unlike the first embodiment shown in FIG. 2, an insulating light-shielding film material is used in place of the conductive light-shielding film. First, in step A, a transparent conductive film 32 is entirely formed on a substrate 31. Next, in step B, a resist 33 is applied on the transparent conductive film 32 and patterned in a matrix. In step C, the transparent conductive film 32 is etched through the resist 33 to be processed into a pixel electrode 34.
In this example, the dimensional shape of the pixel electrode 34 is obtained by performing just etching. However, it is needless to say that under etching may be performed. Subsequently, in step D, an insulating light-shielding film is formed on the entire surface of the substrate 31. As a result, the light-shielding film 35 is buried in the portion where the transparent conductive film 32 has been removed by etching, and the black mask 36 is formed by self-alignment.
Can be formed. As a method for forming the light-shielding film, an evaporation method, a sputtering method, a CVD method, a spray method, a coating method, a printing method, or the like can be used. For example, when a spray method, a coating method, or a printing method is used, a black ink, a black resist, or the like can be used as an insulating light-shielding film material. Finally, step E
The used resist 33 is stripped off, and unnecessary portions of the light shielding film are simultaneously removed. When the lift-off method is used in this way, the photolithography of the resist only needs to be performed once, and not only the alignment between the photomasks is unnecessary, but also
The number of steps can be significantly reduced.

FIG. 4 is a process chart showing a third embodiment of the black mask forming method according to the present invention. In this example, a black mask is formed by coloring the substrate surface instead of the light-shielding film to form a light-shielding region. First, in step A, a transparent conductive film 42 is entirely formed on the substrate 41. This film is
For example, ITO or the like may be deposited or sputtered. Next, in step B, the resist 43 is patterned in a matrix. Further, in step C, the transparent conductive film 42 is
Is etched to process the pixel electrode 44. In this example, overetching is performed, and an undercut 45 is provided below the edge of the resist 43. Next, the light-shielding region 46 is selectively applied to the base surface from which the transparent conductive film 42 has been etched away in the process D by applying an ion implantation method.
To form For example, by ion-implanting metal particles or the like with a high energy or a high dose, the surface of the substrate 41 exposed at the opening of the resist 43 is discolored metallically and becomes an effective black mask. Shading area 4
Even when 6 has conductivity, no problem occurs because it is separated from the pixel electrode 41 via the undercut 45.
Finally, the resist 43 used in the step E is peeled off. As a result, the pixel electrode 44 and the black mask 47 are formed on the substrate 41 by self-alignment.

FIG. 5 is a process chart showing a fourth embodiment of the black mask forming method according to the present invention. Unlike the third embodiment shown in FIG. 4, a light shielding region serving as a black mask is formed by using a dyeing method. First, in step A, a transparent conductive film 52 is formed on the surface of the substrate 51. Next, in step B, the resist 53 is patterned in a matrix. Subsequently, in the process C, the transparent conductive film 52 is just etched through the resist 53 to be processed into the pixel electrode 54. In this example, since a non-conductive light-shielding region is formed, over-etching of the pixel electrode is not required. Next, in step D, a light-shielding region 55 is formed on the exposed surface of the substrate 51 by a staining method. At this time, it is preferable that the surface of the substrate 51 is covered with a layer that can be easily dyed. For example, a transparent resin material that can be easily colored can be used for the flattening layer shown in FIG. Finally, in step E, the resist 53
Is peeled off. As a result, the black mask 56 and the pixel electrode 54 are formed on the surface of the substrate 51 by self-alignment. In addition, it is also possible to form a non-conductive light-shielding region by an ion implantation method instead of the staining method.

[0018]

As described above, according to the present invention, an on-chip black structure can be formed by self-alignment. Therefore, there is an effect that the alignment accuracy between the pixel electrode and the black mask is dramatically improved. or,
Since the lift-off method is used, there is an effect that the number of steps in the production of the black mask can be drastically reduced. Further, since the lift-off method is used, there is no need to consider the etching rates of the transparent conductive film material forming the pixel electrode and the light-shielding film material forming the black mask, and there is an effect that the degree of freedom in material selection increases. In addition, since the lift-off method is used, a step due to the pattern of the previously formed pixel electrode does not affect a subsequent process. Therefore, there is an effect that the edge gap between the pixel electrode and the black mask can be reduced. In addition, according to the present invention, the pixel electrode and the black mask can be electrically separated by over-etching the transparent conductive film. For this reason, a metal or the like can be used as the light shielding film material, and there is an effect that the selection range of the material is expanded. Finally, since the black mask and pixel electrode can be created on the same layer, the surface of the substrate is flattened,
There is an effect that the alignment control of the liquid crystal becomes easy.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view showing a completed product of an active matrix display device manufactured according to the present invention.

FIG. 2 shows a first example of a black mask forming method according to the present invention.
It is process drawing which shows an Example.

FIG. 3 is a process chart showing a second embodiment.

FIG. 4 is a process drawing showing a third embodiment.

FIG. 5 is a process chart showing a fourth embodiment.

FIG. 6 is a process chart showing an example of a conventional black mask forming method.

FIG. 7 is a process chart showing another conventional method.

FIG. 8 is a process chart showing another conventional method.

FIG. 9 is a process drawing showing still another conventional step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Driving substrate 2 Counter substrate 3 Liquid crystal 5 Pixel electrode 6 Black mask 7 Switching element

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hisao Hayashi 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-2-72330 (JP, A) JP-A Sho 63-144305 (JP, A) JP-A-6-118218 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1368 G02B 5/20

Claims (2)

(57) [Claims] 1. A drive substrate provided with a matrix-shaped pixel electrode, a black mask bordering each pixel electrode, and a switching element for driving each pixel electrode, and a counter substrate provided with a counter electrode are joined to each other. What is claimed is: 1. A method for manufacturing an active matrix display device comprising an electro-optical material held between substrates, comprising: a film forming step of forming a transparent conductive film on a drive substrate provided with switching elements in advance; A patterning step of etching the transparent conductive film through the resist thus formed into a pixel electrode, a black mask forming step of forming a black mask by self-alignment through the remaining resist, and a lift-off for removing the resist Wherein the patterning step comprises over-etching the transparent conductive film.
To provide an undercut under the resist edge
The black mask forming step is performed through the undercut.
And form a black mask in a state separated from each pixel electrode.
A method for manufacturing an active matrix display device, comprising: 2. A pixel electrode having a matrix shape and individual pixel electrodes.
A black mask that borders the poles and a switch that drives each pixel electrode
A driving substrate having an etching element and a counter electrode
The opposing substrate is bonded to each other, and the electro-optical material is
Of manufacturing active matrix display device holding
A law, transparent on a driving substrate in advance switching element is provided
A film forming step of forming a conductive film, and the film forming process through a resist patterned in a matrix.
Patterning to etch bright conductive film and process it into pixel electrodes
Process and self-alignment through the remaining resist
A black mask forming step of forming a black mask; and a lift-off step of removing the resist, wherein the black mask forming step includes etching the transparent conductive film.
Ion in plantation against ring removed underlying table surface
Specially, the shading area is selectively formed by applying the
A method for manufacturing an active matrix display device.