JP3865823B2 - Method for producing transparent electrode substrate and method for producing liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a liquid crystal display device using the manufacturing method of making and transparent electrode substrate of a transparent electrode substrate, in particular the liquid crystal display device is an active matrix type liquid crystal display device using a switching element LCD The present invention relates to a method for manufacturing a display device .
[0002]
[Prior art]
In a transparent pixel electrode of an active matrix type liquid crystal display device using a conventional thin film transistor (TFT), after forming a TFT on the surface of a transparent substrate, an indium tin oxide (ITO) film is deposited on the entire surface of the substrate, and this ITO film It was formed by patterning.
[0003]
[Problems to be solved by the invention]
In order to reduce the manufacturing cost of the liquid crystal display device, it is desired to reduce the number of processes by simplifying the manufacturing method. In a conventional method for manufacturing a liquid crystal display device, an independent process for forming a transparent pixel electrode, such as formation and patterning of an ITO film, is required. For this reason, there is a limit in reducing the number of processes.
[0004]
An object of the present invention is to provide a method for manufacturing a liquid crystal display device manufacturing method and an active matrix type transparent electrode substrate that can reduce the number of manufacturing steps.
[0005]
[Means for Solving the Problems]
According to one aspect of the present invention, the surface of a glass substrate containing an oxide of Ba is treated with a strong acid, Ba contained in the surface of the glass substrate is leached , and the altered layer is deficient in Ba on the surface of the glass substrate. forming a well as depositing a metal film on the surface of the affected layer after the missing of Ba of the altered layer, in place of Ba, contain a metal that forms the metal film, based on transparent electrode to a thickness portion of the altered layer, and forming a transparent conductive layer having conductivity, and a step of exposing the transparent conductive layer metal film is partially removed on the transparent conductive layer A method for making a substrate is provided.
[0006]
According to another aspect of the present invention, a plurality of glass substrates containing an oxide of Ba and a plurality of glass substrates containing a Ba oxide are formed on one surface of the glass substrate using the method for producing the transparent electrode substrate of the present invention. It is, to leach Ba from the glass substrate, which is formed corresponding to each of the other metal a transparent pixel electrode conductivity is imparted by containing the transparent pixel electrode on the glass substrate instead A switching element having a pair of current terminals and a control terminal for controlling opening and closing of a current path between the pair of current terminals, wherein one current terminal is connected to a corresponding transparent pixel electrode; and is formed on the other of the signal lines for applying a signal voltage to a current terminal of the switching element, it is formed on the glass substrate, and a control line for applying a control signal to the control terminal of the switching element Preparation A transparent electrode substrate, another transparent substrate disposed to face the one surface of the glass substrate in the transparent electrode substrate, and a transparent common electrode formed on a facing surface of the other transparent substrate, A liquid crystal display device manufacturing method for manufacturing a liquid crystal display device having a liquid crystal layer sandwiched between the glass substrate and another glass substrate, wherein the surface of the glass substrate containing an oxide of Ba is made of a strong acid. A step of leaching Ba contained in the surface of the glass substrate to form an altered layer lacking Ba on the surface of the glass substrate; and depositing a metal film on the surface of the altered layer; and A step of forming a transparent conductive layer having conductivity in the thickness portion of the original deteriorated layer by including, in place of Ba, the metal forming the metal film in the trace of Ba in the deteriorated layer being removed; Part of the metal film on the transparent conductive layer And removing the transparent conductive layer, leaving the control terminal and the control line made of the metal film, and patterning the exposed transparent conductive layer, and exposing the control terminal to the exposed region of the transparent conductive layer. And a step of forming a plurality of transparent pixel electrodes insulated from both of the control lines .
[0008]
The transparent pixel electrode can be formed without depositing a transparent conductive layer for forming the transparent pixel electrode.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A method for manufacturing a liquid crystal display according to an embodiment of the present invention will be described with reference to FIGS.
[0010]
In the step shown in FIG. 1A, the surface of the aluminoborosilicate glass substrate 1 containing Ba oxide is treated with sulfuric acid to which hydrogen peroxide is added to leach Ba. Ba is dissolved in sulfuric acid from the glass substrate 1, and the altered layer 2 deficient in Ba is formed on the surface. A strong acid other than sulfuric acid to which hydrogen peroxide water is added, for example, nitric acid or hydrochloric acid heated to about 120 ° C. may be used.
[0011]
In the step shown in FIG. 1B, a Cr film 3 having a thickness of about 150 nm is deposited on the surface of the altered layer 2 by, for example, sputtering. Cr enters the trace of Ba from the deteriorated layer 2, and the transparent conductive layer 2 a is formed in the thickness portion of the original deteriorated layer 2. In addition, you may use metals other than Cr which can form a transparent conductive layer, for example, transition metals, such as Ti, Mo, and Ta, Al, etc.
[0012]
In the step shown in FIG. 1C, the region where the gate electrode of the TFT is to be formed is covered with a resist pattern 4, and the Cr film 3 is partially etched to leave the gate electrode 3a. Etching of the Cr film is performed using, for example, a mixed aqueous solution of nitric acid and ceric ammonium nitrate.
[0013]
At this time, in a region other than the cross section shown in FIG. 1C, a plurality of control lines extending in the horizontal direction in the figure are also formed at the same time. The gate electrode 3a continues to one corresponding control line. After patterning the Cr film 3, the resist pattern 4 is removed.
[0014]
In the step shown in FIG. 1D, a region where a TFT gate electrode 3a, a control line (not shown), and a transparent pixel electrode are to be formed is covered with a resist pattern 5. The transparent conductive layer 2a is partially etched using the resist pattern 5 as an etching mask and using, for example, hydrofluoric acid as an etchant. A transparent pixel electrode 2b that is insulated from both the gate electrode 3a and the control line is formed. The transparent conductive layer 2c remains under the gate electrode 3a.
[0015]
After patterning the transparent conductive layer 2a, the resist pattern 5 is removed. Note that the transparent conductive layer 2a may be patterned by leaving the resist pattern 4 used in the step of FIG. 1C as it is on the gate electrode 3a and further forming a resist pattern 5.
[0016]
In the step shown in FIG. 1E, a gate insulating film 6 made of SiN having a thickness of about 400 nm, a channel layer 7 made of amorphous silicon and having a thickness of about 30 nm, and a thickness made of SiN so as to cover the entire surface of the substrate. A 120 nm channel protective film 8 is deposited in this order.
[0017]
The gate insulating film 6 is deposited using, for example, SiH _{4 with} a flow rate of 220 sccm, NH _{3 with} a flow rate of 3900 sccm, and N ₂ with a flow rate of 2000 sccm as a source gas, a pressure of 213.3 Pa, a high-frequency power of 2500 W, and a substrate temperature of 320 ° C. Plasma enhanced chemical vapor deposition (PE-CVD) is used.
[0018]
The channel layer 7 is deposited, for example, by PE-CVD using SiH _{4 with} a flow rate of 120 sccm and H ₂ with a flow rate of 1000 sccm as a source gas, a pressure of 173.3 Pa, a high-frequency power of 120 W, and a substrate temperature of 310 ° C.
[0019]
The channel protective film 8 is deposited using, for example, SiH _{4 with} a flow rate of 160 sccm, NH _{3 with} a flow rate of 900 sccm, and N ₂ with a flow rate of 2000 sccm, a pressure of 213.3 Pa, a high-frequency power of 2100 W, and a substrate temperature of 320 ° C. This is performed by PE-CVD.
[0020]
In the step shown in FIG. 2A, the channel protective film 8 is patterned to leave the channel protective film 8a in a region substantially corresponding to the gate electrode 3a. The channel protective film 8 is etched by dry etching using, for example, CF ₄ or SF ₆ with a flow rate of 200 to 300 sccm and O ₂ with a flow rate of 100 to 150 sccm, a pressure of 1 Torr, and a high frequency power of 200 to 800 W.
[0021]
In the step shown in FIG. 2B, a source / drain layer made of amorphous silicon doped with P and made into n ⁺ type is deposited on the entire surface of the substrate. The source / drain layer and the channel layer 7 are patterned at the same time to form the channel region 7a and the source / drain layer 9 above the gate electrode 3a and the regions near both sides thereof. This two-layer etching is performed, for example, by dry etching using SF ₆ + Cl ₂ with a flow rate of 200 to 300 sccm as a mixing ratio of 1: 1 as an etching gas and a pressure of 0.3 Torr and a high frequency power of 200 to 800 W.
[0022]
A contact hole 11 is formed in the gate insulating film 6 to expose a part of the upper surface of the transparent pixel electrode 2b. The contact hole 11 is formed by dry etching using CF ₄ or SF ₆ with a flow rate of 200 to 300 sccm and O ₂ with a flow rate of 100 to 150 sccm, a pressure of 1 Torr, and a high frequency power of 200 to 800 W.
[0023]
In the step shown in FIG. 2C, a Ti / Al wiring layer having a laminated structure composed of lower Ti and upper Al is deposited on the entire surface of the substrate. The Ti / Al wiring layer and the source / drain layer 9 are patterned as follows.
[0024]
The source / drain layer 9 is separated to the left and right in the figure at the approximate center of the channel protective film 8a to form a drain region 9D located on the opposite side of the transparent pixel electrode 2b and a source region 9S located on the transparent pixel electrode 2b side. By the Ti / Al wiring layer, the source wiring 10S that connects the source region 9S and the transparent pixel electrode 2b, the drain electrode 10D that covers the drain region 9D, and the drain electrode 10D extend in a direction perpendicular to the drawing sheet. A signal line 10L is formed.
[0025]
Etching of the Ti / Al layer and the source / drain layer 9 uses, for example, Cl ₂ + BCl ₃ having a flow rate of 200 to 300 sccm and a mixing ratio of 1: 1 as an etching gas, a pressure of 0.1 Torr, and a high frequency power of 1.1 to 1.5 kW. The dry etching is performed under the conditions described above.
[0026]
After the step shown in FIG. 2C, a protective film made of SiN having a thickness of about 330 nm is deposited, and an alignment film is formed on the protective film. For the deposition of the protective film, for example, SiH _{4 with} a flow rate of 160 sccm, NH _{3 with} a flow rate of 1000 sccm, and N ₂ with a flow rate of 2100 sccm are used as the source gas, the pressure is 213.3 Pa, the high-frequency power is 2000 W, and the substrate temperature is 250 ° C. Performed by PE-CVD.
[0027]
FIG. 3 is a partial plan view schematically showing the liquid crystal display device according to the above embodiment. A cross-sectional view taken along one-dot chain line AA in FIG. 3 corresponds to FIG. A plurality of control lines 3L extend in the horizontal direction in FIG. 3, and a plurality of signal lines 10L extend in the vertical direction. The TFT 20 is arranged corresponding to the intersection of the control line 3L and the signal line 10L. The transparent pixel electrode 2b is arranged in a region surrounded by two control lines 3L and two signal lines 10L adjacent to each other. The gate, drain, and source of the TFT 20 are connected to the corresponding control line 3L, signal line 10L, and transparent pixel electrode 2b, respectively.
[0028]
According to the above embodiment, the surface of the aluminoborosilicate glass substrate is treated with a strong acid to cause alteration, and the altered layer is imparted with conductivity to obtain a transparent pixel electrode. For this reason, the process of depositing an ITO film, which has been conventionally used as a transparent pixel electrode, can be omitted.
[0029]
In the above embodiment, in the step shown in FIG. 2 (C), the connection between the source region 9S and the transparent pixel electrode 2b of the TFT, but are connected by the source wiring 10S formed by laminating Ti and Al, the source wiring 10S A single layer film of Al or Al alloy may be used. When ITO is used as the transparent pixel electrode and the ITO film and Al are brought into direct contact, there is a case where the ITO is reduced due to the battery effect due to the difference in electronegativity and the transparent pixel electrode is blackened. In the case of the present embodiment, since the difference in potential negativity between the transparent pixel electrode and Al is relatively small, such a problem is unlikely to occur even when Al is brought into direct contact with the transparent pixel electrode. By using an Al single layer film, the resistance can be further reduced.
[0030]
In the above-described embodiment, the case where aluminoborosilicate glass is used as the glass substrate has been described. However, other substrates may be used as long as the altered layer capable of imparting conductivity is formed on the surface. For example, borosilicate glass or the like may be used.
[0031]
Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.
[0032]
【The invention's effect】
As described above, according to the present invention, a transparent pixel electrode can be formed without forming an ITO film. For this reason, the manufacturing process and the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a substrate for explaining a method of manufacturing a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a substrate for explaining a method of manufacturing a liquid crystal display device according to an embodiment of the present invention.
FIG. 3 is a partial plan view schematically showing a liquid crystal display device according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Alteration layer 2a, 2c Transparent conductive layer 2b Transparent pixel electrode 3 Cr film 3a Gate electrode 3L Control line 4, 5 Resist pattern 6 Gate insulating film 7 Channel layer 8, 8a Channel protective film 9 Source / drain layer 9D Drain Region 9S Source region 10D Drain electrode 10S Source wiring 10L Signal line 11 Contact hole 20 TFT

Claims (6)

Treating the surface of the glass substrate containing an oxide of Ba with a strong acid, leaching Ba contained in the surface of the glass substrate to form an altered layer deficient in Ba on the surface of the glass substrate ;
The metal film is deposited on the surface of the deteriorated layer, and the metal that forms the metal film is included in place of Ba in the traces of Ba in the deteriorated layer. Forming a transparent conductive layer having conductivity on the part ;
The method for manufacturing a transparent electrode substrate, which comprises a step of exposing the transparent conductive layer metal film is partially removed on the transparent conductive layer. 2. The transparent electrode substrate according to claim 1, further comprising a step of patterning the exposed transparent conductive layer and forming a plurality of transparent pixel electrodes insulated from each other in the exposed region of the transparent conductive layer. Manufacturing method. 3. The transparent electrode substrate according to claim 1, wherein the strong acid is at least one acid selected from the group consisting of sulfuric acid to which hydrogen peroxide is added, heated nitric acid, and heated hydrochloric acid. Manufacturing method. In the step of exposing the transparent conductive layer, the metal film on the transparent conductive layer is partially removed, leaving control terminals and control lines made of the metal film,
3. The method according to claim 2, wherein in the step of forming the transparent pixel electrode by patterning the exposed transparent conductive layer, the transparent pixel electrode is formed to be insulated from both the control terminal and the control line. A method for producing a transparent electrode substrate. A method for producing a transparent electrode substrate according to claim 1 , wherein a plurality of glass substrates containing an oxide of Ba and a plurality of glass substrates are formed on one surface of the glass substrate so as to be spaced apart from each other. A transparent pixel electrode that has been leached, and instead contains other metals to provide conductivity, and is formed on the glass substrate corresponding to each of the transparent pixel electrodes, and a pair of current terminals and the A switching terminal connected to a corresponding transparent pixel electrode, and a switching terminal connected to a corresponding transparent pixel electrode, and the switching element. A transparent electrode substrate comprising: a signal line for applying a signal voltage to the other current terminal; and a control line formed on the glass substrate for applying a control signal to the control terminal of the switching element ; Transparent Another transparent substrate disposed to face the one surface of the glass substrate in the bright electrode substrate, a transparent common electrode formed on the facing surface of the other transparent substrate, the glass substrate and the other A liquid crystal display device manufacturing method for manufacturing a liquid crystal display device having a liquid crystal layer sandwiched between a glass substrate ,
Treating the surface of the glass substrate containing an oxide of Ba with a strong acid, leaching Ba contained in the surface of the glass substrate to form an altered layer deficient in Ba on the surface of the glass substrate;
The metal film is deposited on the surface of the deteriorated layer, and the metal that forms the metal film is included in place of Ba in the traces of Ba in the deteriorated layer. Forming a transparent conductive layer having conductivity on the part;
Removing the metal film on the transparent conductive layer partially, leaving a control terminal and a control line made of the metal film, and exposing the transparent conductive layer;
And patterning the exposed transparent conductive layer, and forming a plurality of transparent pixel electrodes insulated from both the control terminal and the control line in the exposed region of the transparent conductive layer. Device manufacturing method. The method further includes the step of electrically connecting the one current terminal of the switching element and the transparent pixel electrode to form a wiring in which Al or an Al alloy is in direct contact with the transparent pixel electrode. Item 6. A method for manufacturing a liquid crystal display device according to Item 5.

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