JPH10307303A - Liquid crystal display substrate, its production and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display substrate with good dimensional accuracy in a channel part by forming source electrodes and drain electrodes in a metal film forming process to form a multilayered metal film and in an etching process to etch the multilayered metal film into a specified shape. SOLUTION: A chromium film 10 and a pure copper film 13 with each specified thickness are continuously deposited by sputtering on the whole surface of a substrate where layers are to be formed, then a positive photoresist is applied on the surface of the copper film 13 and exposed to light and developed to form a resist layer with a wiring pattern of source electrodes 6 and drain electrodes 7. Then the exposed part of the copper film 13 is removed by wet etching by dipping in an etching liquid (A) under specified conditions. Further, the substrate is dipped in an etching liquid (B) under specified conditions so that the exposed chromium film 10 and a n<+> layer 42 and the surface layer of an i-layer 42 under the chromium film are removed to about 30 nm depth. Thereby, the source electrode 6, the drain electrode 7 and a channel part 12 of a semiconductor film 4 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to an active matrix type liquid crystal display substrate having thin film transistors, a method of manufacturing the same, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A typical liquid crystal display device, a TFT-L
CD (Thin Film Transistor-Liquid Crystal Displa
y: A thin film transistor-liquid crystal display device is an active matrix type liquid crystal display substrate (TF) as a liquid crystal display substrate.
T substrate). An example of this TFT substrate is shown in FIGS. FIG. 4 is a plan view of the transistor portion of the substrate, and FIG. 5 is a cross-sectional view taken along aa 'in FIG.

As shown in FIGS. 4 and 5, a TFT substrate includes a transparent pixel electrode 5 provided in a matrix on a transparent substrate 1, a gate electrode 2 serving as a switching element of the pixel electrode 5, A thin film transistor including a film 4, a source electrode 6, and a drain electrode 7. Normally, a gate insulating film 3 is provided between the gate electrode 2 and the pixel electrode.
The source electrode 6 and the pixel electrode 5 are electrically connected to each other. Further, the semiconductor film 4, the source electrode 6 and the drain electrode 7 are covered with a passivation film 8. The semiconductor film 4 is usually made of a-Si (Amorph
ous Silicon: amorphous silicon) and includes an i-layer 41 and an n + layer 42.

In a conventional liquid crystal display device using a TFT substrate, selected transistors (a gate electrode 2 usually called a gate line and a drain electrode 7 usually called a data line) are used.
Is provided at only the intersection with the pixel), and the voltage of the pixel is maintained at a constant value, thereby controlling the alignment of the liquid crystal of the cell to perform light switching. Since the degree of liquid crystal alignment is determined by the voltage applied to the screen, it is necessary to apply the same voltage to each pixel when driven under the same conditions regardless of the selection address of the gate line and the drain line. If the voltage is not constant, the amount of transmitted light of the pixel deviates from the set value, causing unevenness in brightness and color, and significantly lowers the display quality.

However, if the electrical resistance of the gate line 2 and the drain line 7 is high, the delay of the drive signal and the degree of voltage drop due to the wiring differ depending on the address of the pixel.
The time and voltage for driving T vary depending on the wiring distance, and as a result, the voltage of the pixel electrode 5 varies depending on the wiring distance. However, a driver IC for driving
Since the (Integrated Circuit) is arranged around the display unit, it is inevitable that the wiring distance between the driver IC and the pixel electrode 5 differs depending on the address of the pixel. Therefore, as the screen size of the display device increases, problems such as uneven brightness and color become more serious. Usually, the value of the wiring resistance required to ensure the complete display quality of the liquid crystal display device is about 20 kΩ or less, preferably 10 kΩ or less.
It is considered to be less than kΩ, more preferably less than 5 kΩ.

Therefore, aluminum wiring is used for the gate line 2 and the drain line 7 to reduce the resistance of the wiring. For a TFT substrate using this aluminum wiring, for example, see Tsukada and Yamamoto, "Anodic Oxide Al Gate TFT for Liquid Crystals, Compatible with High Yield and Low Wiring Resistance" (Nikkei Micro Devices, March 1991, pp. 107-113). )
Y, Tsumura, Mikami, Saito, "10-inch High Definition Color TF
Adopt double shielding, Al gate technology, etc. for T liquid crystal "(Nikkei Micro Devices, April 1991, pages 105 to 111).
The details are described in.

In general, a TFT substrate is formed by forming a gate electrode 2 on a glass substrate 1 and then forming a gate insulating film 3 and an i.
A-Si film 4 composed of layer 41 and n + layer 42 is
After deposition using VD (Chemical Vapor Deposition), the a-Si film 4 is processed into an island shape, the gate insulating film 3 is processed into a predetermined shape, and then ITO (Indium Tin Oxide) is formed on the pixel portion. Forming a transparent electrode 5 of
After forming the source electrode 6 and the drain electrode 7, unnecessary n
It is manufactured by removing the + layer and finally forming the passivation film 8.

In the case where the gate electrode 2 is formed of aluminum, a gate wiring pattern is formed of aluminum on the glass substrate 1 and then formed on the surface of the formed aluminum wiring in order to prevent a hillock which is a problem inherent in aluminum. To form an anodized film. For forming the anodic oxide film, a method is used in which the substrate is immersed in an anodic oxidation solution and electrolysis is performed using aluminum wiring as an anode.

When the source electrode 6 and the drain wiring 7 are formed of aluminum, aluminum and a-S
A contact layer made of Cr, which is a refractory metal, is formed between the substrate and i, and the contact layer is etched after aluminum is etched into a predetermined shape to expose the exposed n +. A method of etching the layer 42 using the wiring pattern of the source electrode 6 and the drain electrode 7 as a mask is used.

[0010]

As described above, when an aluminum wiring is used for the source electrode 6 and the drain wiring 7, the wiring needs to be formed by a laminated film of a contact layer and an aluminum layer. However, in this case, etching of the contact layer becomes a problem. This problem will be described in detail with reference to FIG. FIG. 3 shows a series of steps from the formation of the a-Si island 4 to the formation of the source wiring 6 and the drain wiring 7 to the etching of the n + layer 41 using a sectional view.

First, a gate electrode 2 is placed on a glass substrate 1.
After forming the gate insulating film 3 and an island composed of the amorphous silicon i-layer 41 and the n + layer 42, the contact Cr layer 10 and the aluminum layer 11 are sputtered to form a laminated surface of the substrate (ie, The gate electrode 2, the gate insulating film 3, and the semiconductor film 4 are continuously deposited on the entire surface (FIG. 3A).

Next, after forming a photoresist layer of a source and drain wiring pattern on the surface of the aluminum layer 11, unnecessary portions of the aluminum layer 11 are removed by using an aluminum etchant, and the resist is peeled off (FIG. 4). 3 (B)). At this time, the channel portion 12 which determines the operation dimensions of the TFT is formed by the etching.

As the aluminum etchant, for example, an aqueous solution having a composition such as 75 parts by weight of phosphoric acid, 5 parts by weight of nitric acid, 8 parts by weight of acetic acid and water in an amount of 100 parts by weight in total is used.

Next, the contact chromium layer 10 exposed in the channel portion is removed with a strongly acidic etchant to expose the n + layer 42 in the channel portion (FIG. 3).
(C)). Here, it is necessary to use an etching solution that does not affect the dimensions of aluminum as the etching solution used for etching chromium. For example, cerium ammonium nitrate 15 parts by weight Perchloric acid 5 parts by weight Water The amount of 100 parts by weight An aqueous solution having such a composition is used.

Finally, the exposed n + layer 4 is exposed through a mask of the wiring pattern of the source electrode 6 and the drain electrode 7.
2 is removed by dry etching (FIG. 3D).
At this time, in order to completely remove the n + layer 42, the i-layer 4
It is common to remove some of the 1 as well. This dry etching is usually performed by converting a gas serving as a halogen radical source such as SF ₆ into plasma.

As described above, the gate electrode 2, the semiconductor unit 4,
A transistor portion including the source electrode 6 and the drain electrode 7 is formed. However, when aluminum wiring is used, wet etching of chromium progresses in the horizontal direction (that is, erodes the side surface), that is, so-called side etching occurs. It deviates from the dimension of the channel portion at 11. N + of the semiconductor unit 4
Since the layer 42 is etched using the chromium layer 10 immediately above it as a mask, if side etching occurs in the chromium layer 10, the dimension of the channel portion of the n + layer 42 also deviates from the dimension of the aluminum layer 11. As a result, the channel dimension of the transistor deviates from a predetermined value.

The amount of side etching of the chromium layer 10 may range from 0.2 to 2 μm, which causes a change in channel dimensional accuracy in the semiconductor portion 4 as described above, and also causes foreign matter and scratches. This also caused disconnection of the wiring due to penetration of the etching solution.

Accordingly, an object of the present invention is to provide a liquid crystal display substrate having good dimensional accuracy of a channel portion, a liquid crystal display device using the substrate, and a method of manufacturing the liquid crystal display substrate.

[0019]

According to the present invention, there is provided an active matrix type liquid crystal display substrate having a wiring layer in which a source electrode and a drain electrode are formed of a conductor having a smaller ionization tendency with respect to water than hydrogen.
A liquid crystal display device using the substrate is provided.

Further, in the present invention, the source electrode and the drain electrode are formed as a multilayer metal film in which a contact layer made of a high melting point metal having a higher melting point than the conductor constituting the wiring layer and the wiring layer are laminated. A method for manufacturing an active matrix type liquid crystal display substrate formed by a metal film forming step and an etching step of etching a multilayer metal film into a predetermined shape is provided.

According to the present invention, a conductor having a smaller ionization tendency with respect to water than a hydrogen is used for the wiring layer of the source electrode and the drain electrode, so that it cannot be used in the case of aluminum wiring for etching the contact layer and the semiconductor portion. An alkaline solution can be used. Therefore, the etching solution and the etching conditions for the contact layer and / or the semiconductor film can be appropriately selected so that side etching does not occur. For example, an alkaline solution containing permanganic acid or the like can be used as the etching solution. . Since aluminum is eroded by the alkaline aqueous solution, an alkaline etchant cannot be used for aluminum wiring.

Therefore, the present invention provides an active matrix comprising at least one of a step of etching a contact layer of a source electrode and a drain electrode with an aqueous solution of an alkaline oxidant and a step of etching a semiconductor film with an aqueous solution of an alkaline oxidant. A method for manufacturing a liquid crystal display substrate is provided. Note that the contact layer and the semiconductor film may be sequentially etched by one etching step. That is, the contact layer of the source electrode and the drain electrode of the channel portion and the semiconductor film up to the predetermined depth of the channel portion are collectively etched and removed by being brought into contact with a predetermined etching solution for a predetermined time. Good.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An active matrix type liquid crystal display substrate of the present invention usually comprises a transparent substrate (such as a glass plate),
A gate electrode formed on the surface of the transparent substrate; a gate insulating film formed on the surface of the transparent substrate so as to cover the gate electrode; and pixel electrodes arranged in a matrix. A source electrode disposed so as to be in contact with, a semiconductor film disposed so as to cover at least a part of the gate electrode via a gate insulating film, and a drain electrode opposed to the source electrode via a channel portion having a predetermined width. Is provided, and a passivation film is formed on the surface of the gate insulating film so as to cover the source electrode, the semiconductor film, and the drain electrode. The source electrode and the drain electrode according to the present invention include a wiring layer made of a conductor having a smaller ionization tendency with respect to water than hydrogen. The pixel electrode may be on any surface of the transparent substrate, the gate insulating film, and the passivation film.

A liquid crystal display device using this substrate is:
After bonding a TFT substrate and a transparent substrate (a color filter substrate in the case of a color display device) and sealing liquid crystal in a gap between the two substrates, a polarizing plate, a driving circuit, a backlight, a light guide plate, etc. are mounted. TFT substrate, a transparent substrate (a color filter substrate in the case of a color display device), a liquid crystal sealed between them, a liquid crystal sealing member, a polarizing plate, a driving circuit, a backlight, A light guide plate and the like are provided.

Examples of the conductor having a lower ionization tendency than water include hydrogen, such as copper, silver, gold, and platinum, and alloys containing any of these metals. It is desirable to use. When a copper alloy is used, it is preferable to contain copper as a main component (that is, 50% by weight or more), and it is preferable to use pure copper or a copper alloy containing 95% by weight or more of copper from the viewpoint of etching characteristics. The resistivity of this metal material is 2 to 10
μΩcm is more preferable because the wiring resistance is lower than that of conventionally used aluminum.

When a copper alloy is used for the wiring layer, alloy components other than copper include metal components such as tin, zinc, nickel and aluminum, semimetal components such as silicon and germanium, or phosphorus and sulfur. It is desirable to use such a non-metal component or a combination thereof, and it is preferable to select a component that does not increase the wiring resistance.

The source electrode and the drain electrode are formed, for example, by forming a film of this metal material by a deposition means such as sputtering and forming the film into a wiring pattern by etching using a photoresist as a mask. The thickness of this wiring layer is desirably 500 nm or less so that the amount of steps formed on the substrate does not affect other steps, and is 50 nm or more so that the wiring resistance does not become unnecessarily large. It is desirable that

The source electrode and the drain electrode of the present invention may be composed of only a wiring layer. However, in order to secure the connection reliability between the semiconductor portion 4 and the wiring layer, a wiring layer is formed between them. It is desirable to provide a contact layer made of a high melting point metal having a melting point higher than that of the conductor. That is, it is desirable that the source electrode and the drain electrode are formed of a multilayer metal film in which a contact layer and a wiring layer are stacked. For the contact layer, for example, chromium, titanium, molybdenum, or the like can be used. From the viewpoint of processability such as etching, it is recommended to use chromium. In addition,
The multilayer metal film forming the source electrode and the drain electrode is not limited to two layers, and may be a stacked film of three or more layers.

The thickness of the contact layer is desirably 5 nm or more so as to obtain a desired adhesive effect. In order to prevent the stress of the contact layer from affecting the warpage of the substrate and the like,
Alternatively, from the viewpoint of economics of film formation and processing, 100 nm
It is preferable to set the following.

Also, the gate electrode is preferably formed using copper or an alloy containing copper, similarly to the source electrode and the drain electrode. As described above, the wiring resistance is lower than that of aluminum.

As the semiconductor film, besides the above-mentioned amorphous silicon, a film of a semiconductor such as polycrystalline silicon or CdSe can be used.

The method of manufacturing a liquid crystal display substrate according to the present invention includes, for example, the following steps.

(1) Gate electrode forming step of forming a gate electrode on the surface of a transparent substrate (2) A gate insulating film covering the gate electrode and the following a to c
Forming an electrode and a semiconductor film which is disposed on a gate electrode with a gate insulating film interposed therebetween and has a concave portion having a predetermined depth in a channel portion a. Pixel electrodes arranged in a matrix b. A source electrode arranged to be adjacent to the pixel electrode c. A drain electrode opposed to the source electrode via a channel portion having a predetermined width; and (3) a passivation film forming step of forming a passivation film on the surface of the gate insulating film so as to cover the source electrode, the semiconductor film, and the drain electrode. Can be selected as appropriate.
For example, after forming a semiconductor film and processing it into an island shape, processing a gate insulating film into a predetermined shape, then forming a pixel electrode in a pixel portion, forming a source electrode and a drain electrode, The channel portion of the semiconductor film may be etched.

In the above example, the gate electrode is formed first, but the pixel electrode may be formed first. That is, as shown in FIG. 1, a transparent pixel electrode 5 is first formed in a pixel portion on a transparent substrate 1, then a gate electrode 2 is formed, and then a gate insulating film 3, an i layer and an n layer are formed.
An a-Si film 4 composed of a + layer is deposited. Next, a-S
After the i film 4 is processed into an island shape and the gate insulating film 3 is processed into a predetermined shape, the source electrode 6 and the drain electrode 7 are processed.
And removing the n + layer in the channel portion,
Finally, a passivation film having a predetermined shape is formed. When each electrode is formed in this order, as shown in FIG. 1, a liquid crystal display substrate in which the transparent electrode 5 is arranged on the same plane as the gate electrode 2 (that is, the surface of the transparent substrate 1) is obtained.

In some cases, it is possible to arrange the transparent electrode 5 on the surface of the passivation film 8. That is, after the gate electrode 2 is formed on the transparent substrate 1, the gate insulating film 3 and the semiconductor film 4 are deposited, the semiconductor film 4 is processed into an island shape, and then the gate insulating film is processed into a predetermined shape. Thereafter, the source electrode 6 and the drain electrode 7 are formed, the n + layer in the channel portion is removed, and then a passivation film having a shape exposing a predetermined position of the source electrode 6 is formed. The pixel electrode may be formed so as to be in contact with the electrode 6.

The preceding and following relations of the manufacturing process and the vertical relation between the wirings described above are merely examples of the TFT substrate manufacturing method, and the present invention can be applied to any case.

In the present invention, the source electrode and the drain electrode are formed by (c1) a pixel electrode forming step of forming a pixel electrode on the gate insulating film surface, a semiconductor film forming step of forming a semiconductor film on the gate insulating film surface. A metal film forming step of forming a multilayer metal film (a film in which a contact layer and a wiring layer are laminated) on the surface of the gate insulating film so as to be in contact with the pixel electrode and to cover the semiconductor film; (c2) the multilayer metal film Etching step to form a source electrode and a drain electrode.

In the etching step according to the present invention, when the source electrode and the drain electrode are formed of a laminated film having a contact layer, a layer (ie, a wiring layer) other than the contact layer is etched to have a predetermined wiring shape. It is desirable to include an etching step and a contact layer etching step of etching the contact layer with a channel etchant. In the contact layer etching step, the contact layer and the semiconductor film up to a predetermined depth may be continuously etched to form a channel portion. When the source electrode and the drain electrode do not have the contact layer, only the semiconductor film is etched by the channel etchant.

As described above, in the present invention, in order to prevent side etching of the contact layer, an alkaline aqueous solution containing an oxidizing agent can be used as the channel etching solution. As the oxidizing agent, permanganate, permanganate, dichromate, dichromate, or the like can be used. Further, it is desirable that the channel etching solution contains a pH adjuster so as to have a predetermined pH according to the oxidizing agent. As the pH adjuster, for example, hydroxides and / or weak acid salts (eg, silicates, phosphates, etc.) of alkali metals and / or alkaline earth metals can be used.

The concentration of permanganate ion or dichromate ion is desirably 0.05 mol / L or more so that a practical etching rate can be secured, and the solubility of the salt and the etching rate are not excessive. Therefore, it is desirable to set the concentration to 0.5 mol / L or less. Further, the pH should be set so that a practical etching rate can be obtained, and is usually set to pH 12 to 14. The channel etching includes the oxidizing agent described above,
In addition to the pH adjuster, a pH buffer and other oxidizing agents may be included.

The aqueous solution of the alkaline oxidizing agent contains thin Cr
When dissolving the layer, it has the excellent feature that etching does not proceed in the horizontal direction at all, but has the property of eroding aluminum because it is strongly alkaline. However, in the present invention, the wiring layer is made of a conductor whose ionization tendency with respect to water is smaller than that of hydrogen, and is not affected by such an alkaline etchant. Therefore, according to the present invention, the channel portion can be formed with high dimensional accuracy.

Further, since this strong alkaline etching solution also gradually dissolves amorphous silicon, the contact layer and the n + layer can be formed only by contacting the silicon for a predetermined time.
The surface layer of the i-layer can be continuously removed. Therefore, according to the present invention, not only can the channel portion be formed with extremely high dimensional accuracy, but also the channel portion, which conventionally required two steps of wet etching of Cr and dry etching of the semiconductor film, has been changed to 1 This has the advantage that the etching can be performed by one wet etching. Therefore, according to the present invention, not only can a liquid crystal display substrate be manufactured in a smaller number of steps than in the conventional case, but gas and equipment for dry etching of a semiconductor film are not required, so that the manufacturing cost is reduced. It can be kept low.

Next, a description will be given of a specific example of a manufacturing process in the case where each of the gate, source, and drain wirings is formed using copper.

The wiring of the gate electrode 2 is formed by depositing copper on the entire surface of a transparent substrate (eg, a glass substrate) 1 by deposition means such as sputtering, and then forming a photoresist of a predetermined shape on the surface of the deposited film. After that, an unnecessary portion of the deposited film is removed with an etching solution for dissolving copper, and then the photoresist is peeled off to form a film. If the gate electrode 2 is formed using copper as described above, an extremely low-resistance wiring without hillocks can be formed.

The source wiring and the drain wiring are formed, for example, by the steps shown in FIG. That is, first, the gate electrode 2 and the gate insulating film 3 are formed on the transparent substrate 1.
And an island comprising an amorphous silicon i-layer 41 and an n + layer 42, and then a contact Cr layer 1
0 and the copper layer 13 are continuously deposited on the entire surface of the laminated surface of the substrate (that is, the surface on which the gate electrode 2, the gate insulating film 3 and the semiconductor film 4 are formed) by sputtering, and the contact layer 10 and the copper wiring layer 13 are formed. (FIG. 2A) is obtained.

The source wiring 6 is formed on the surface of the multilayer metal film 20.
After forming a photoresist having a pattern of the drain wiring 7 and immersing the photoresist in a copper etching solution to remove unnecessary portions of the multilayer metal film 20, the resist is peeled off (FIG. 2).
(B)). By the etching at this time, a channel portion 12 for determining the operation size of the TFT is formed. As the copper etchant, for example, an aqueous solution having a composition such that phosphoric acid is 70 parts by weight, nitric acid is 10 parts by weight, acetic acid is 8 parts by weight, and the total amount is 100 parts by weight is used. Hereinafter, the etching solution having this composition is referred to as an etching solution A. The etching solution for the wiring layer in the present invention is not limited to this, and a normal processing solution known as a copper wet etching solution can be used as long as it does not affect other components such as the contact layer.

Next, the contact layer 10 exposed in the channel portion, and the n + layer 42 and the i-layer 41
The whole is dissolved and removed with a channel etching solution (FIG. 2C). Here, as the etchant used for etching the channel portion, for example, an aqueous solution having a composition such as potassium permanganate 4 parts by weight, sodium metasilicate 6 parts by weight, and the total amount of water being 100 parts by weight can be used. This etchant exhibits a strong alkalinity of about pH13. The etching solution having this composition is hereinafter referred to as an etching solution B.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a liquid crystal display device is manufactured by applying the present invention will be described below with reference to the drawings. A. 1. Manufacturing of Liquid Crystal Display Substrate First, a manufacturing process of an active matrix type liquid crystal display substrate will be described with reference to FIGS.

(1) Step of Forming Gate Electrode First, a glass substrate 1 having a display size of 20 inches diagonally and a thickness of 0.7 mm, which is about 370 mm long and about 470 mm wide, can be formed. (Asahi Glass Co., Ltd. “AN635 Glass”) was prepared and washed according to a conventional method. A 300 nm pure copper film was deposited on the surface of the glass substrate by sputtering. The metal resistance of this copper film was about 3 μΩcm.

A positive photoresist is applied to the surface of the copper film with a spinner, and after drying the solvent, the photoresist is exposed to light using a predetermined photomask and developed using an organic alkali developing solution to form a gate wiring pattern. Resist layer (1μ thick)
m) was formed. Next, the exposed portion of the copper film was immersed in the above-mentioned etching solution A at 40 ° C. for 3 minutes to remove it by wet etching, and then the resist layer was peeled off. Thus, the gate electrode 23 was formed.

The gate electrode 23 of this embodiment has a wiring width of 1
Despite having a fine line of about 0 μm, the resistance from the gate terminal to the terminal end was extremely low, less than 5 kΩ. In addition, since the wiring thickness was small, there was no harmful step, and the wiring was excellent without hillocks.

(2) Transistor forming step Next, on the side of the substrate 1 on which the gate electrode 23 is formed (hereinafter, referred to as a lamination side), the gate electrode 23 is covered.
Using a plasma CVD method (input power: 100 W / cm ² ) using SiH ₄ and NH ₃ ,
An iN (Silicon Nitride) film and an amorphous silicon film (i-layer 41 having a thickness of 100 nm and n + layer 42 having a thickness of 30 nm)
) Were continuously formed.

A positive photoresist is applied to the surface of the obtained a-Si film, and is exposed and developed to form a resist layer having a pattern of the a-Si island 4, and then the exposed portion of the a-Si film is removed. , dry etching using a gas of SF _6, and the resist is removed. Subsequently, a positive photoresist is coated, exposed, and developed on the entire surface on the lamination side of the substrate so as to cover the remaining a-Si film, and a resist layer having a pattern of the gate insulating film 3 is formed. The exposed part is S
Dry etching was performed using F ₆ gas to remove the resist layer. Thereby, the gate insulating film 3 and the a-Si layer 4
Was formed.

Next, an ITO film having a thickness of 140 nm is deposited on the entire lamination side of the substrate by sputtering, and a positive photoresist is applied, exposed and developed on the surface of the obtained ITO film to form a pixel electrode 5. A resist layer having a pattern was formed. Next, the exposed portion of the ITO film was removed by wet etching using aqua regia as an etchant, and then the resist was removed. As a result, a transparent pixel electrode 5 was formed.

Subsequently, a 50-nm-thick chromium film 10 and a 30-mm-thick
After a 0 nm pure copper film 13 is continuously deposited (FIG.
(A)) A positive photoresist was applied, exposed, and developed on the surface of the copper film 13 to form a resist layer of a wiring pattern of the source electrode 6 and the drain electrode 7. Next, the exposed portion of the copper film 13 was added to the etching solution A at 40 ° C. for 3 hours.
After immersion in the etching solution B for 10 minutes at room temperature, the exposed chromium film 10 and the underlying n + layer 42 are immersed in the etching solution B for 10 minutes. And about 30 of the surface layer of the i-layer 41.
nm was removed by etching (FIG. 2C). Thereby, the source electrode 6, the drain electrode 7, and the semiconductor film 4
Channel portion 12 was formed.

The wiring formed as described above had an extremely low resistance value from the drain terminal to the terminal end of less than 5 kΩ. Further, in the channel etching step using the etching solution B, no side etching of the chromium film 10 was observed at all.

(3) Passivation Film Forming Step Lastly, a 300 nm-thick SiN film is formed on the entire lamination side of the substrate by a plasma CVD method (input power: 100 W / cm ² ) using SiH ₄ and NH _3. A positive photoresist was applied to the surface of the obtained SiN film, exposed, and developed to form a resist layer having a pattern of a passivation film. Next, after the exposed portion of the SiN film was dry-etched using SF ₆ gas, the resist was removed. Thus, the passivation film 8 was formed, and the TFT substrate shown in FIG. 1 was completed.

(4) Quality Inspection When the dimensional accuracy of the channel portion of the obtained TFT substrate was measured, the relative dimensional error of the channel portion in the wiring layer 13, the contact layer 10, and the a-Si film 4 was 0.2 μm.
It was below.

The obtained TFT substrate (display size:
After laminating a separately prepared color filter substrate with a diagonal 20 inches), TN (Twi
(sedNematic) After sealing the liquid crystal, a predetermined voltage is applied to the terminals of the gate wiring 23 and the drain wiring 7 drawn around the TFT substrate. The display quality of the TFT substrate is determined by a so-called lighting test. It was an excellent thing that was not seen.

In the same manner as in this example, TFT substrates having various display sizes were manufactured. Table 1 shows the wiring resistance and the display quality determination result. The wiring resistance values shown in Table 1 are obtained by calculating the resistance value for a wiring having a width of 10 μm. In addition, the result of the judgment of the display quality is that the color display of the color display does not cause unevenness and is uniform over the entire screen.
The samples having slight unevenness in color but having no practical effect were evaluated as “practical”, and those not suitable for practical use due to uneven color were evaluated as “bad”.

[0061]

[Table 1]

As is apparent from Table 1, according to the manufacturing method of this embodiment, the wiring resistance can be suppressed to 10 kΩ or less over a wide range of display sizes of 12 to 40 inches diagonally. It could be reduced to 5 kΩ or less. Therefore, according to the manufacturing method and the liquid crystal display substrate of this example, it was found that a large-screen liquid crystal display device with excellent display quality could be provided.

B. Production of Liquid Crystal Display Device After bonding the obtained TFT substrate and a separately prepared color filter substrate, TN (T
(wisted Nematic) After enclosing the liquid crystal, a polarizing plate, a driving circuit, a backlight, a light guide plate, and the like were mounted to manufacture a liquid crystal display device. As a result, a liquid crystal display device with excellent display quality was obtained.

[0064]

According to the present invention, it is possible to obtain a liquid crystal display substrate with high dimensional accuracy of the channel portion and a liquid crystal display device using the substrate.

[Brief description of the drawings]

FIG. 1 TF of an active matrix type liquid crystal display substrate
It is sectional drawing of the T section.

FIG. 2 is an explanatory view showing a manufacturing process of an a-Si transistor portion in the embodiment.

FIG. 3 is an explanatory view showing a manufacturing process of a conventional a-Si transistor part.

FIG. 4 TF of an active matrix type liquid crystal display substrate
It is a top view of T part.

FIG. 5: TF of an active matrix type liquid crystal display substrate
It is sectional drawing of the T section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Gate electrode, 3 ... Gate insulating film,
Reference numeral 4 denotes a semiconductor film, 5 denotes a pixel electrode, 6 denotes a source electrode, 7 denotes a drain electrode, 8 denotes a passivation film, 10 denotes a contact layer, 11 denotes a wiring layer (aluminum layer), 12 denotes a channel portion, and 13 denotes a wiring layer (copper). Layers), 20 ... multilayer metal film, 23
... gate electrode, 41 ... i layer, 42 ... n + layer.

Claims (9)

[Claims] 1. A metal film forming step of forming a metal film including a wiring layer made of a conductor whose ionization tendency with respect to water is smaller than that of hydrogen, and an etching step of etching the metal film into a predetermined shape. And a method for manufacturing an active matrix type liquid crystal display substrate. 2. The manufacturing method according to claim 1, wherein the metal film forming step comprises: laminating a contact layer made of a high melting point metal having a melting point higher than that of the conductor; An active matrix type, comprising: a wiring layer etching step of etching the wiring layer; and a contact layer etching step of etching the contact layer using a channel etchant. A method for manufacturing a liquid crystal display substrate. 3. The manufacturing method according to claim 2, wherein said wiring layer is made of copper or an alloy containing copper, said high melting point metal is at least one of chromium, titanium and molybdenum, and said channel etching is performed. The method for manufacturing an active matrix liquid crystal display substrate, wherein the liquid is an alkaline aqueous solution containing an oxidizing agent. 4. A method of etching a contact layer of a source electrode and a drain electrode with an alkaline aqueous solution containing an oxidizing agent, and a step of etching a semiconductor film using a channel etching solution that is an alkaline aqueous solution containing an oxidizing agent. A method for manufacturing an active matrix type liquid crystal display substrate, comprising: 5. The method according to claim 1, further comprising the step of etching and removing the contact layer of the source electrode and the drain electrode of the channel portion and the semiconductor film to a predetermined depth by contacting the semiconductor layer with the etching solution for a predetermined time. Of manufacturing an active matrix type liquid crystal display substrate. 6. The method according to claim 5, wherein said etchant is an alkaline aqueous solution containing an oxidizing agent. 7. The method according to claim 3, wherein the oxidizing agent is selected from the group consisting of permanganate, permanganate, dichromate, and dichromate. A method for manufacturing an active matrix type liquid crystal display substrate, characterized by comprising: 8. An active matrix liquid crystal display substrate, wherein the source electrode and the drain electrode include a wiring layer made of a conductor having a smaller ionization tendency with respect to water than hydrogen. 9. A liquid crystal display device comprising the liquid crystal display substrate according to claim 8.