WO2009081993A1

WO2009081993A1 - Process for producing display

Info

Publication number: WO2009081993A1
Application number: PCT/JP2008/073656
Authority: WO
Inventors: Mototaka Ochi; Hiroshi Goto
Original assignee: Kabushiki Kaisha Kobe Seiko Sho
Priority date: 2007-12-26
Filing date: 2008-12-25
Publication date: 2009-07-02
Also published as: JP2009175720A; TW200952079A; TWI378509B; JP4611418B2

Abstract

A process for producing a display which has a structure including a transparent conductive oxide film and an aluminum alloy film which serves as a reflective electrode and has been disposed on and directly connected to the oxide film. The process comprises: a first step in which a transparent conductive oxide film is formed on a substrate; a second step in which an aluminum alloy film is formed on the transparent conductive oxide film; and a third step in which the aluminum alloy film is heated to a given temperature. The aluminum alloy film contains 0.1-4 at.% nickel of cobalt and 0.1-2 at.% lanthanum. The given temperature in the third step is determined according to the nickel or cobalt content and the temperature of the substrate at which the aluminum alloy film is formed in the second step. The aluminum alloy film formed in this process is less apt to be corroded by alkaline developing solutions such as an aqueous TMAH solution.

Description

Manufacturing method of display device

The present invention relates to a method for manufacturing a display device represented by a liquid crystal display, an organic electroluminescence (EL) display, or the like. Specifically, the present invention relates to a method for manufacturing a display device having a structure in which an oxide transparent conductive film and an Al alloy film for a reflective electrode are directly connected, and alkaline corrosion during patterning of the Al alloy film. The present invention relates to a method for manufacturing a display device that can effectively prevent the above. In the following, a liquid crystal display will be described as a representative example, but the present invention is not limited to this.

There are two types of liquid crystal displays: a transmissive display device that uses light from a lighting device (backlight) installed behind the liquid crystal panel as a light source, a reflective display device that uses ambient light, and both transmissive and reflective types. It is roughly divided into a semi-transmission type display device having both.

Among these, the transmissive display device performs display by allowing the backlight irradiated from the rear surface of the liquid crystal panel to pass through the liquid crystal panel and the color filter, and performs display with a high contrast ratio regardless of the use environment. It has the advantage of being capable of being used, and is widely used in electronic devices that require large brightness such as televisions and personal computer monitors. However, since power for the backlight is required, it is somewhat unsuitable for small devices such as mobile phones.

On the other hand, a reflective display device reflects natural light or artificial light in a liquid crystal panel and displays the reflected light through a liquid crystal panel or a color filter. It is widely used mainly for calculators and watches. However, the reflective display device has a drawback that the brightness and contrast ratio of the display are greatly affected by the use environment, and in particular, it becomes difficult to see when it becomes dark.

In contrast, transflective display devices use reflective electrodes during the day to save power consumption, and light and turn on lights when necessary indoors or at night, depending on the usage environment. Since the display in the transmissive mode and the display in the reflective mode can be performed, there is an advantage that power consumption can be saved without being restricted by the surrounding environment, and a bright high contrast ratio display can be obtained. The transflective display device is optimally used for mobile devices, and in particular, is widely used for colored mobile phones and the like.

Referring to FIGS. 1 and 2, the configuration and operation principle of a typical transflective liquid crystal display device will be described. 1 and 2 correspond to FIGS. 1 and 2 disclosed in Patent Document 3 described later.

As shown in FIG. 1, a transflective liquid crystal display device 11 includes a thin film transistor (hereinafter referred to as “TFT”) substrate 21, a counter substrate 15 disposed to face the TFT substrate 21, and a TFT A liquid crystal layer 23 is provided between the substrate 21 and the counter substrate 15 and functions as a light modulation layer. The counter substrate 15 includes a color filter 17 including a black matrix 16, and a transparent common electrode 13 is formed on the color filter 17. On the other hand, the TFT substrate 21 has a pixel electrode 19, a switching element T, and a wiring portion including a scanning line and a signal line. In the wiring portion, a plurality of gate wirings 5 and a plurality of data wirings 7 are arranged perpendicular to each other, and a switching element TFT (in the figure, T) are arranged in a matrix.

As shown in detail in FIG. 2, the pixel area P of the pixel electrode 19 is composed of a transmissive area A and a reflective area C. The transmissive area A is a transparent pixel electrode 19a, and the reflective area C is a transparent pixel electrode 19a. A reflective electrode 19b is provided. A barrier metal layer 51 made of a refractory metal such as Mo, Cr, Ti, or W is formed between the transparent pixel electrode 19a and the reflective electrode 19b. For example, in Patent Documents 1 to 3, a barrier metal layer 51 such as Mo or Cr is interposed between an Al-based alloy film and an oxide transparent conductive film.

The operation principle of the transmissive mode and the reflective mode of the transflective liquid crystal display device 11 shown in FIG. 1 will be described with reference to FIG.

First, the operation principle of the transmission mode will be described.
In the transmissive mode, the light F of the backlight 41 disposed below the TFT substrate 21 is used as a light source. Light emitted from the backlight 41 enters the liquid crystal layer 23 via the transparent pixel electrode 19a and the transmission region A, and liquid crystal molecules in the liquid crystal layer 23 are generated by an electric field formed between the transparent pixel electrode 19a and the common electrode 13. , And the incident light F from the backlight 41 passing through the liquid crystal layer 23 is modulated. As a result, the amount of light transmitted through the counter substrate 15 is controlled to display an image.

On the other hand, in the reflection mode, external natural light or artificial light B is used as a light source. The light B incident on the counter substrate 15 is reflected by the reflective electrode 19b, and the alignment direction of the liquid crystal molecules in the liquid crystal layer 23 is controlled by the electric field formed between the reflective electrode 19b and the common electrode 13. The passing light B is modulated. As a result, the amount of light transmitted through the counter substrate 15 is controlled to display an image.

The pixel electrode 19 includes a transparent pixel electrode 19a and a reflective electrode 19b. Among these, the transparent pixel electrode 19a is typically indium tin oxide (ITO) containing about 10% by mass of tin oxide (SnO) in indium oxide (In ₂ O ₃ ), or zinc oxide in indium oxide. It is formed from an oxide transparent conductive film such as indium zinc oxide (IZO) containing about mass%.

The reflective electrode 19b is made of a metal material having high reflectivity, and is typically an Al alloy such as pure Al or Al—Nd (hereinafter, these are collectively referred to as “Al-based alloy”). Is used. Al-based alloys are extremely useful as wiring materials because of their low electrical resistivity.

Here, as shown in FIG. 2 and Patent Documents 1 to 3 described above, between the Al-based alloy film constituting the reflective electrode 19b and the transparent oxide conductive film such as ITO or IZO constituting the transparent pixel electrode 19a. The reason why the refractory metal barrier metal layer 51 such as Mo is formed is that if the reflective region is formed by directly connecting them, the contact resistance increases due to galvanic corrosion or the like, and the display quality of the screen decreases.

Galvanic corrosion is said to occur when the electrode potential difference between different metals is large, such as an oxide transparent conductive film such as ITO and an Al-based alloy film. For example, the electrode potential with respect to an Ag / AgCl standard electrode in an aqueous tetramethylammonium hydroxide (TMAH) solution that is an alkaline developer of photoresist is about -0.17 V for amorphous-ITO and about -0.19 V for poly-ITO. On the other hand, pure Al is very low at about -1.93V. Furthermore, Al-based alloys are very easily oxidized. Therefore, when an Al alloy film is directly formed on the oxide transparent conductive film and patterned, an Al oxide insulating layer is formed at the interface between the Al alloy film and the oxide transparent conductive film during immersion in the TMAH aqueous solution. Produced and corroded. When the TMAH aqueous solution penetrates into the interface with the oxide transparent conductive film along the pinholes and through grain boundaries generated in the Al-based alloy film and galvanic corrosion occurs at the interface, various problems such as oxide transparent conductive Blackening of the film, resulting in blackening of the pixel, poor pattern formation such as wiring thinning and disconnection, an increase in contact resistance between the Al alloy film and the oxide transparent conductive film, resulting in defective display (lighting).

However, the method of interposing the barrier metal layer has problems such as a complicated manufacturing process and an increase in production cost.

Therefore, “direct contact technology” that can omit the formation of the barrier metal layer and can directly contact the Al alloy film with the transparent pixel electrode has been studied. The direct contact technology is required to have a low contact resistance between the Al alloy film, which is an electrode material, and the transparent pixel electrode and to have excellent heat resistance so that a display device with high display quality can be obtained.

The present applicant is not intended for a display device having a structure in which an Al alloy film for a reflective electrode is directly connected on an oxide transparent conductive film as in the present invention. As a technique, the method described in Patent Document 4 is proposed. Patent Document 4 discloses an Al alloy film wiring material containing 0.1 to 6 atomic% of at least one alloy element selected from the group consisting of Au, Ag, Zn, Cu, Ni, Sr, Ge, Sm, and Bi. Is disclosed. If the Al alloy film is used, a conductive alloy element-containing precipitate is formed at the interface between the Al alloy film and the transparent pixel electrode, and generation of an insulating material such as aluminum oxide is suppressed. Can be reduced. Moreover, if the addition amount of the alloy element is within the above range, the electrical resistivity of the Al alloy itself can be kept low. Further, if at least one alloy element of Nd, Y, Fe, and Co is further added to the Al alloy film, generation of hillocks (cove-like projections) can be suppressed, and heat resistance can be improved. The precipitate of the alloy element is subjected to a heat treatment (annealing) at 150 to 400 ° C. (preferably 200 to 350 ° C.) for 15 minutes to 1 hour after forming an Al alloy film on the substrate by sputtering or the like. Obtained by.
JP 2004-144826 A JP 2005-91477 A JP 2005-196172 A JP 2004-214606 A

An object of the present invention is to prevent corrosion in an alkaline developer such as an aqueous TMAH solution in a display device having a structure in which an Al alloy film for a reflective electrode is directly connected on a transparent oxide conductive film. It is an object of the present invention to provide a method for manufacturing a display device capable of effectively preventing corrosion of an alloy film.

A manufacturing method of a display device according to the present invention that has solved the above problems is a manufacturing method of a display device having a structure in which an Al alloy film for a reflective electrode is directly connected on an oxide transparent conductive film, A first step of forming the oxide transparent conductive film thereon, a second step of forming the Al alloy film on the oxide transparent conductive film, and a third step of heating the Al alloy film; The Al alloy film includes 0.1 to 4 atomic% of at least one of Ni and Co, and 0.1 to 2 atomic% in total of at least one element selected from group X. It is made of an Al— (Ni / Co) —X alloy contained in a range, where X is La, Mg, Cr, Mn, Ru, Rh, Pt, Pd, Ir, Ce, Pr, Gd, Tb, Dy, Nd Ti, Zr, Nb, Mo, Hf, Ta, W, Y, Fe, S , Eu, Ho, Er, Tm, Yb, and Lu, the second step depending on at least one of the Ni content and the Co content of the Al— (Ni / Co) —X alloy film The present invention has a gist in controlling the substrate temperature and the heating temperature in the third step.

In a preferred embodiment, the Al alloy film contains 0.5 to 4 atomic% of at least one of Ni and Co.

In a preferred embodiment, the Al alloy film contains 0.5 to 4 atomic% of Ni.

In a preferred embodiment, the temperature of the substrate in the second step and the heating temperature in the third step are as follows according to the Ni content (atomic%, [Ni]) of the Al alloy film: It is controlled as in (3).
(1) When the substrate is not heated in the second step, the heating temperature in the third step is increased to 200 ° C. by a temperature of 50 ° C. or less set according to α (4- [Ni]). Control within the specified temperature range.
(2) When the substrate temperature is controlled to 100 ° C. or higher and lower than 150 ° C. in the second step, the heating temperature in the third step is set according to α (4- [Ni]) 100 The temperature below ℃ is controlled within the temperature range plus 100 ℃.
(3) When the substrate temperature is controlled to 150 ° C. or higher and 250 ° C. or lower in the second step, the heating temperature in the third step is set according to α (4- [Ni]) 100 The temperature below ℃ is controlled within the temperature range plus 100 ℃.

In a preferred embodiment, the Al— (Ni / Co) —X alloy film includes at least one of 0.1 to 4 atomic% of Ni and Co, and at least of 0.1 to 2 atomic% of La and Nd. And one.

In a preferred embodiment, the Al— (Ni / Co) —X alloy film further comprises at least one element selected from the group consisting of 0.1 to 2 atomic% Z (Z is Ge, Cu, and Si). Is contained).

In a preferred embodiment, the Al— (Ni / Co) —X alloy film includes at least one of 0.1 to 4 atomic% of Ni and Co, and at least of 0.1 to 2 atomic% of La and Nd. 1 and at least one of 0.1 to 2 atomic% of Ge and Cu.

In the production method of the present invention, it is preferable to use a tetramethylammonium hydroxide (TMAH) aqueous solution during patterning of the Al alloy film. In the production method of the present invention, a preferable oxide transparent conductive film is indium tin oxide (ITO) or indium zinc oxide (IZO).

According to the present invention, the thermal history (specifically, the substrate temperature at the time of film formation and the heating temperature after the film formation) of the Al alloy film as the reflective electrode is determined according to the amount of Ni and / or Co contained in the Al alloy film. Therefore, even when immersed in an alkaline developer such as TMAH aqueous solution during patterning, corrosion of the Al alloy film is suppressed, and the contact resistance between the transparent oxide conductive film and the Al alloy film is reduced. can do.

FIG. 1 is an exploded perspective view showing a configuration of a typical transflective liquid crystal display device. FIG. 2 is a diagram schematically showing a cross section of a typical transflective liquid crystal display device. FIG. 3 is a graph showing the immersion potential of an Al alloy film (Al-2 atomic% Ni-0.35 atomic% La) formed by changing the substrate temperature during sputtering. FIG. 4 is a graph showing the reflectivity of a pure Al film and an Al—Ni—La alloy film (reflection electrode) in which the amount of Ni is changed (composition unit in the graph is atomic%). FIG. 5 shows the sample No. after being immersed in the TMAH aqueous solution in the example. 19 is an optical micrograph of 19 (Al-2 atomic% Ni-0.35 atomic% La film, substrate temperature = room temperature, no heat treatment). FIG. 6 shows the sample No. after being immersed in the TMAH aqueous solution in the example. 19 is 19 transmission electron micrographs. FIG. 7 shows the sample No. after being immersed in the TMAH aqueous solution in the example. 23 is an optical micrograph of No. 23 (Al-2 atomic% Ni-0.35 atomic% La film, substrate temperature = room temperature, heat treatment temperature = 250 ° C.). FIG. 8 shows the sample No. after being immersed in the TMAH aqueous solution in the example. 23 is a transmission electron micrograph of 23. FIG. 9 is a diagram showing a Kelvin pattern (TEG pattern) used for measuring the connection resistance between the Al alloy film and the oxide transparent conductive film (ITO film). FIG. 10 is a graph showing the influence of the heating temperature and the amount of Ni on the alkali corrosion resistance when the substrate temperature is formed at room temperature in an Al—Ni—La alloy film. FIG. 11 is a graph showing the influence of the heating temperature and the amount of Ni on the alkali corrosion resistance when the substrate temperature is increased to 100 ° C. in an Al—Ni—La alloy film. FIG. 12 is a graph showing the influence of the heating temperature and the amount of Ni on the alkali corrosion resistance when the substrate temperature is increased to 150 ° C. and 250 ° C. in an Al—Ni—La alloy film. is there. FIG. 13 is a graph showing the influence of the heating temperature and the amount of Ni on the alkali corrosion resistance when the substrate temperature is formed at room temperature in an Al—Ni—La—Cu alloy film. FIG. 14 is a graph showing the influence of the heating temperature and the amount of Ni on the alkali corrosion resistance when the substrate temperature is increased to 100 ° C. in an Al—Ni—La—Cu alloy film. . FIG. 15 shows the effect of heating temperature and Ni amount on the alkali corrosion resistance when the substrate temperature is increased to 150 ° C. and 250 ° C. in an Al—Ni—La—Cu alloy film. It is a graph. FIG. 16 is a graph showing the influence of the heating temperature and the amount of Ni on the alkali corrosion resistance when the substrate temperature is formed at room temperature in an Al—Ni—La—Ge alloy film. FIG. 17 is a graph showing the influence of the heating temperature and the amount of Ni on the alkali corrosion resistance when an Al—Ni—La—Ge alloy film is formed at a substrate temperature increased to 100 ° C. . FIG. 18 shows the effect of heating temperature and Ni amount on the alkali corrosion resistance when the substrate temperature is increased to 150 ° C. and 250 ° C. in an Al—Ni—La—Ge alloy film. It is a graph.

Explanation of symbols

5 gate wiring 7 data wiring 11 transflective liquid crystal display device 13 common electrode 15 counter substrate 16 black matrix 17 color filter 19 pixel electrode 19a transparent pixel electrode 19b reflective electrode 21 TFT substrate 23 liquid crystal layer 41 backlight 51 barrier metal layer T switching Element (TFT)
P Pixel area A Transmission area B Ambient light (artificial light source)
C Reflection area F Light from backlight

The present inventors represent a TMAH aqueous solution or the like when patterning an Al alloy film in a display device having a structure in which an Al alloy film for a reflective electrode is directly connected on an oxide transparent conductive film. In order to prevent corrosion (galvanic corrosion) of the Al alloy film that occurs when an alkaline developer of photoresist is used, studies have been repeated. As a result, in accordance with the Ni content of the Al alloy film, a method for appropriately controlling the substrate temperature during the formation of the Al alloy film and the heating temperature after the formation of the Al alloy film, specifically, the heating temperature after the film formation. As a result, the inventors have found that the intended purpose can be achieved by adopting a method in which the amount of Ni in the Al alloy film is controlled in consideration of the relationship with the substrate temperature during film formation, and the present invention has been completed.

Furthermore, Co may be used instead of Ni as the Al alloy film, and Co has also been found to be a synergistic element having the same action as Ni. Ni and Co may be used alone or in combination. Therefore, when the Al alloy film contains only Co, the Al alloy film is formed according to the amount of Co. On the other hand, when the Al alloy film contains both Ni and Co, the Al alloy film is formed according to the Ni amount and the Co amount. It was found that the substrate temperature at the time and the heating temperature after the Al alloy film formation may be appropriately controlled. Further, according to the method of the present invention, 0.1 to 2 atomic% of the group Z (the group Z is at least one element selected from the group consisting of Ge, Cu, and Si) in the Al alloy film. It was found that the present invention can also be applied to the case of further containing.

Hereinafter, an Al alloy containing Ni and / or Co and at least one group X may be referred to as an Al— (Ni / Co) —X alloy. In addition, an Al alloy further including at least one of group Z in the Al— (Ni / Co) —X alloy may be referred to as an Al— (Ni / Co) —XZ alloy. The amounts of Ni, Co, and group Z in the Al alloy film are represented by [Ni], [Co], and [Z]. [Z] means a single amount when the group Z element is contained alone, and a total amount when two or more group Z elements are contained.

Hereinafter, the production method of the present invention will be described in detail. In the following, for convenience of explanation, as the Al alloy film used in the present invention, (i) an Al— (Ni / Co) —X alloy film is used, and (ii) Al— (Ni / Co) —XZ. This will be described separately for the case of using an alloy film.

(I) When using Al— (Ni / Co) —X alloy film The manufacturing method of the present invention is a display having a structure in which an Al alloy film for a reflective electrode is directly connected on an oxide transparent conductive film. A device manufacturing method, comprising: a first step of forming the oxide transparent conductive film on a substrate; a second step of forming the Al alloy film on the oxide transparent conductive film; and the Al alloy. And a third step of heating the membrane. The Al alloy film contains Ni and / or Co in an amount of 0.1 to 4 atomic% and Al— (Ni in a total amount of at least one element selected from group X in the range of 0.1 to 2 atomic%. / Co) -X alloy, where X is La, Mg, Cr, Mn, Ru, Rh, Pt, Pd, Ir, Ce, Pr, Gd, Tb, Dy, Nd, Ti, Zr, Nb, Mo, It consists of Hf, Ta, W, Y, Fe, Sm, Eu, Ho, Er, Tm, Yb, and Lu.

The feature of the present invention is that the temperature of the substrate in the second step and the third step depend on the Ni content and / or Co content of the Al— (Ni / Co) —X alloy film. The heating temperature is controlled. First, the characteristic part will be described.

As described above, in the present invention, as a factor to be considered for preventing galvanic corrosion (alkali corrosion resistance), the temperature of the substrate in the second step (that is, the substrate temperature at the time of forming the Al alloy film). The heating temperature in the third step (that is, the heating temperature after forming the Al alloy film) and the Ni amount ([Ni]) and / or Co amount ([Co]) in the Al alloy film are mentioned. Here, the contents of Ni and Co are given because it is considered that these elements combine with Al to form a fine intermetallic compound useful for preventing galvanic corrosion. The generation of fine intermetallic compounds reduces pinholes or the like penetrating the Al alloy film, resulting in improved alkali corrosion resistance. In addition, when a fine intermetallic compound useful for preventing galvanic corrosion is formed at the interface, the contact resistance between the oxide transparent conductive film and the Al alloy film can be kept low. The action of these elements will be described in detail later.

Specifically, depending on the amount of Ni and / or Co in the Al alloy film (a single amount when contained alone, and a total amount when containing both), the temperature of the substrate and The subsequent heating temperature may be controlled as in the following (1) to (3).
(1) When the substrate is not heated in the second step, the heating temperature in the third step is set to 50 ° C. or less that is set according to α {4-([Ni] + [Co])}. The temperature is controlled within the temperature range plus 200 ° C.
(2) When the substrate temperature is controlled to 100 ° C. or higher and lower than 150 ° C. in the second step, the heating temperature in the third step is set to α {4-([Ni] + [Co])}. The temperature of 100 ° C. or less that is set accordingly is controlled within the range of the temperature plus 100 ° C.
(3) When the substrate temperature is controlled to 150 ° C. or higher and 250 ° C. or lower in the second step, the heating temperature in the third step is set to α {4-([Ni] + [Co])}. The temperature of 100 ° C. or less that is set accordingly is controlled within the range of the temperature plus 100 ° C.

For example, when the Al alloy film contains only Ni (that is, in the case of an Al—Ni—X alloy film), the temperature of the substrate and subsequent heating depending on the amount of Ni in the Al alloy film ([Ni]) The temperature may be controlled as in the following (1A) to (3A).
(1A) If the substrate is not heated in the second step, the heating temperature in the third step is increased to 200 ° C. by a temperature of 50 ° C. or less set according to α (4- [Ni]). Control within the specified temperature range.
(2A) When the substrate temperature is controlled to 100 ° C. or higher and lower than 150 ° C. in the second step, the heating temperature in the third step is set according to α (4- [Ni]) 100 The temperature below ℃ is controlled within the temperature range plus 100 ℃.
(3A) When the substrate temperature is controlled to 150 ° C. or higher and 250 ° C. or lower in the second step, the heating temperature in the third step is set according to α (4- [Ni]) 100 The temperature below ℃ is controlled within the temperature range plus 100 ℃.

In the above (1) to (3), in short, when the film is formed with the substrate temperature set to a low room temperature (around 25 ° C.) as in (1) above, the heating temperature after the Al alloy film formation is set. On the other hand, when film formation is performed with the substrate temperature set as high as about 250 ° C. as in (3) above, the heating temperature after film formation can be set low, and these substrate temperature and heating The setting (adjustment) of temperature means that the temperature can be set in consideration of the amount of Ni contained in the Al alloy film. The same applies to (1A) to (3A) above.

Here, the substrate temperature is classified into the above three patterns (1) to (3) because “the lowering (lowering range) of the heating temperature after film formation is controlled in accordance with the increasing (increase width) of the substrate temperature. The manufacturing method (adjustment means) of the present invention “to do” is generally based on the basic experiment of the present inventors that the above three patterns can be arranged.

The “substrate temperature” in the present invention means the temperature of the entire substrate. Therefore, when it is desired to control the substrate temperature to 200 ° C., the substrate temperature may be maintained at 200 ° C. during the film forming process so that the temperature of the entire substrate becomes 200 ° C. or higher.

In addition, the requirement of “α {4-([Ni] + [Co])}” in the above (1) to (3) is that the substrate temperature and the heating temperature depend on the amount of Ni contained in the Al alloy film ([Ni] ) And / or the amount of Co ([Co]) can be controlled and adjusted in a simplified manner for convenience. The coefficient α in the above requirements can be arbitrarily adjusted depending on the substrate temperature, the heating temperature, the composition of the Al alloy film to be used, and the like. “4” in the above requirements is the upper limit (4 atomic%) of the amount of Ni and / or Co that can be contained in the Al alloy film, and the amount of these elements is controlled within the range of 4 atomic%. It represents what can be done. How to actually control is within the scope of the creative ability of those skilled in the art, and those skilled in the art can directly connect the oxide transparent conductive film and the Al alloy film with reference to the results of the examples described later. It can be appropriately determined in consideration of the contact resistance when connected and the degree of alkali corrosion resistance.

Hereinafter, the manufacturing method of the present invention will be described in more detail with reference to FIGS.

(About FIGS. 10 to 12)
FIGS. 10 to 12 use the results of the examples described later, and arrange the relationship between the Ni amount and the heating temperature for each substrate temperature specified in the above (1) to (3). This is an investigation of the effect. Here, an Al—x atomic% Ni—0.35 atomic% La alloy film is used, and the Ni content (x) is in the range of 0 to 3 atomic% as shown in FIGS. FIG. 10 shows the results when the substrate temperature is set to room temperature [corresponding to the above (1)], and FIG. 11 shows the results when the substrate temperature is raised to 100 ° C. [above (2) FIG. 12 shows the results [equivalent to (3) above] when the substrate temperature was further increased to 150 ° C. and 250 ° C. to form a film. In the figure, ◯ means that the alkali corrosion resistance is excellent, and ▲ means that the alkali corrosion resistance is inferior. Details of the evaluation method will be described later.

10 to 12, when the substrate temperature is low, alkali heating cannot be effectively prevented unless the heating temperature is increased as a whole. However, when the substrate temperature is high, the heating temperature is decreased. It can also be seen that alkali corrosion can be suppressed. In addition, the adjustment range of the substrate temperature and the heating temperature (for example, when the substrate temperature is raised, the heating temperature can be lowered, the increase range of the substrate temperature and the decrease range of the heating temperature) depends on the amount of Ni in the Al alloy film. It can be seen that

For example, considering the case where the amount of Ni in the Al alloy film is 2 atomic%, when the substrate temperature is room temperature, it is preferable to control the heating temperature to approximately 250 ° C. or higher, but the substrate temperature is 100 ° C. When the temperature is controlled, the preferable lower limit of the heating temperature can be lowered, and the alkali corrosion resistance is improved by simply heating to 150 ° C. or higher. Furthermore, when the substrate temperature is controlled to 150 to 250 ° C., the preferable lower limit of the heating temperature can be further lowered, and generally good alkali corrosion resistance can be obtained only by heating to 100 ° C. or higher.

Thus, the present invention does not uniformly control the heating temperature after film formation as in Patent Document 4 described above, but considers the amount of Ni in the Al alloy film in relation to the substrate temperature during film formation. However, it has a technical idea in adopting a control method.

Patent Document 4 described above is common to the present invention in that it is a direct contact technique in which heating is performed after forming an Al alloy film, although the configuration of the present invention is different from that of the present invention. However, in Patent Document 4, no consideration is given to the substrate temperature at the time of film formation, and there is no concept of controlling the heating temperature after film formation in relation to the substrate temperature. And the idea of controlling the substrate temperature is different from the present invention.

10 to 12 show the results of using an Al—Ni—X alloy film as the Al alloy film, but when Co is used instead of Ni, that is, the Al—Co—X alloy film is used. When used, it has been confirmed by experiments that the same tendency as described above is observed. Further, it has been confirmed by experiments that the same results as described above can be obtained when both Ni and Co are used instead of Ni, that is, when an Al- (Ni + Co) -X alloy film is used. .

The upper limit of the heating temperature is not particularly limited from the viewpoint of resistance to alkali corrosion, but if it is too high, hillocks and the like are generated in the Al alloy film, and therefore preferably 350 ° C. or less, more preferably 300 ° C. or less. is there.

Specifically, the heat treatment is preferably performed for a predetermined time in a vacuum atmosphere or an inert atmosphere (for example, in a nitrogen atmosphere). Preferred heating conditions at the respective substrate temperatures (1) to (3) are as follows (I) to (III). Actually, the heating temperature may be appropriately adjusted according to the amount of Ni and / or Co (0.5 to 4 atomic%) in the Al alloy film.
(I) When the substrate temperature is room temperature as in (1) above, the preferred heating temperature is about 200 to 250 ° C., and the preferred heating time is about 30 to 60 minutes.
(II) When the substrate temperature is 100 ° C. or higher and lower than 150 ° C. as in (2) above, the preferred heating temperature is about 100 to 200 ° C., and the preferred heating time is about 30 to 60 minutes.
(III) When the substrate temperature is 150 ° C. or higher and 250 ° C. or lower as in (3) above, the preferred heating temperature is about 100 to 200 ° C., and the preferred heating time is about 30 to 60 minutes.

Although the mechanism by which the Al alloy film can be prevented from alkaline corrosion by the method of the present invention is not known in detail, a fine intermetallic compound of Al and Ni and / or Co becomes transparent to an oxide such as an ITO film by heating. Since the concentration of nickel, which has a small ionization tendency, increases at the interface between the conductive film and the Al alloy film, the electrode potential of the Al alloy film shifts to the positive side, and contact with an oxide transparent conductive film such as an ITO film It is conceivable that the potential difference becomes small. As a result, galvanic corrosion due to the developer and etching solution used in the lithography method is less likely to occur. In particular, according to the experiments of the present inventor, the generation of the “fine intermetallic compound of Al and Ni and / or Co” useful for preventing galvanic corrosion is not limited to the heating temperature after film formation. It is assumed that it is also affected by the substrate temperature at the time of film formation.

According to the production method of the present invention, the electrode potential difference between the Al alloy film and the oxide transparent conductive film can be suppressed to about 1.55 V or less, preferably 1.5 V or less.

For reference, FIG. 3 shows the relationship between the immersion time and the immersion potential when immersed in the TMAH aqueous solution. Here, an Al alloy film of Al-2 atomic% Ni-0.35 atomic% La is used, the substrate temperature during film formation is room temperature → no heating sample, and the substrate temperature during film formation is room temperature → 200 ° C. Two types of heated samples were used.

As shown in FIG. 3, the immersion potential immediately after the immersion (about 0.1 minute) is higher by about 100 mV (0.1 V) in the sample heated after the film formation than in the sample not heated after the film formation. Moreover, it can be seen that this state is maintained for about 0.7 minutes after immersion. This result means that the difference from the immersion potential of the ITO film can be kept small for a long time by heating, suggesting that galvanic corrosion can be effectively suppressed.

The Al alloy film used in the present invention contains Ni and / or Co in an amount of 0.1 to 4 atomic% and at least one element selected from group X in a total amount of 0.1 to 2 atomic%. It is made of an Al- (Ni / Co) -X alloy, where X is La, Mg, Cr, Mn, Ru, Rh, Pt, Pd, Ir, Ce, Pr, Gd, Tb, Dy, Nd, Ti, Zr Nb, Mo, Hf, Ta, W, Y, Fe, Sm, Eu, Ho, Er, Tm, Yb, and Lu.

Here, Ni and Co have the effect of reducing the contact resistance with the oxide transparent conductive film, and also have the effect of improving the alkali corrosion resistance (see Examples described later). The reason why the contact resistance with the oxide transparent conductive film is reduced by adding Ni and / or Co to the Al alloy film is unknown in detail, but the interface between the Al alloy film and the oxide transparent conductive film is unknown. This is presumably because a Ni and / or Co-containing precipitate or a Ni and / or Co concentrated layer that can prevent Al diffusion is formed at the (contact interface). The Al alloy film may contain either Ni or Co, or both.

The content of (Ni / Co) in the Al— (Ni / Co) —X alloy film (the amount contained alone is the amount alone, and the amount contained both is the total amount) is described above. In order to effectively exhibit the effect of reducing contact resistance and the effect of improving alkali corrosion resistance, it is necessary to be 0.1 atomic% or more. On the other hand, as shown in FIG. 4 to be described later, when the content of (Ni / Co) exceeds 4 atomic%, the reflectance and electrical resistivity of the Al alloy film are high and cannot be put into practical use. Therefore, the content of (Ni / Co) in the Al alloy film is 0.1 atomic% or more (preferably 0.5 atomic% or more, more preferably 1 atomic% or more, further preferably 2 atomic% or more), 4 atoms. % Or less (preferably 3 atom% or less).

Further, Group X elements (particularly La and Nd) are elements (heat resistance improving elements) that contribute to improving the heat resistance of the Al alloy film. Specifically, the inclusion of at least one of group X can effectively prevent the formation of hillocks (cove-like projections) on the surface of the Al alloy film during heating. These elements may be added alone or in combination of two or more. When two or more elements are contained, the total amount of each element may be controlled so as to satisfy the following range.

In order to sufficiently exhibit such heat resistance improving effect, the content of the element belonging to Group X is 0.1 atomic% or more, preferably 0.2 atomic% or more. However, when the content of these elements becomes excessive, the electrical resistivity of the Al— (Ni / Co) —X alloy film itself increases. Therefore, the content of these elements is 2 atomic% or less, preferably 0.8 atomic% or less.

Considering characteristics such as heat resistance and electrical resistivity, among the elements belonging to Group X, La, Nd, Gd, Tb and Mn are preferable, and La and Nd are more preferable.

In the present invention, the balance of the Al— (Ni / Co) —X alloy film is substantially composed of Al and inevitable impurities.

(Ii) Using Al— (Ni / Co) —XZ Alloy Film Next, a manufacturing method when using an Al— (Ni / Co) —XZ alloy film as the Al alloy film will be described. . This Al alloy film is the same as the Al- (Ni / Co) -X alloy film of (i) described above, and further includes a group Z element (at least one element selected from the group consisting of Ge, Cu, and Si). Is contained in an amount of 0.1 to 2 atom%, and as a result, contact resistance is reduced and heat resistance is further improved. Of the above Z, Ge and Cu are preferred from the viewpoints of reducing contact resistance with the transparent conductive film and improving alkali resistance. It is shown in FIGS. 13 to 15 (Cu addition example) and FIGS. 16 to 18 (Ge addition example) that the alkali resistance is improved by the addition of Ge and Cu. Further, in these figures, all of the examples of ◯ (good alkali corrosion resistance) were suppressed to a low contact resistance of 1500 Ω / cm ² or less (not shown in the figure). Therefore, in the present invention, as the Al— (Ni / Co) —XZ alloy layer, 0.1 to 2 atomic% of Ni and / or Co and 0.1 to 2 atomic% of La and / or Nd are used. It is most preferable to use an alloy layer containing 0.1 to 2 atomic% of Ge and / or Cu.

When the content of Z is less than 0.1 atomic%, the above effect cannot be exhibited effectively. On the other hand, when the content of Z exceeds 2 atomic%, the above effect is improved, but the reflectance is lowered and the electrical resistivity is increased. The Z content is preferably 0.2 atomic percent or more and 0.8 atomic percent or less. Each element of Ge, Cu, and Si belonging to Z may be added alone or in combination of two kinds. When two or more elements are added, the total content of each element may be controlled so as to satisfy the above range.

The design guideline (basic concept) of the manufacturing method when using the Al- (Ni / Co) -XZ alloy film is the same as that when using the Al alloy film of (i) described above, Depending on the amount of Ni ([Ni]) and / or amount of Co ([Co]) in the Al alloy film and the amount of group Z elements ([Z]), the substrate temperature and the subsequent heating temperature are appropriately set. Just control. Specifically, when film formation is performed with the substrate temperature set to a low room temperature (around 25 ° C.) as described above (1), the heating temperature after the Al alloy film formation can be set high, On the other hand, when the film is formed with the substrate temperature set as high as about 250 ° C. as in the above (3), the heating temperature after the film formation can be set low, and the substrate temperature and the heating temperature are set. (Adjustment) can be set in consideration of the amount of (Ni / Co) and the amount of group Z contained in the Al alloy film.

In the case of using the above Al alloy film, the elements to be considered for the prevention of galvanic corrosion (alkali corrosion resistance) include the elements of group Z in addition to the aforementioned contents of Ni and Co. This is because, like Ni and Co, it is considered that these elements combine with Al to form a fine intermetallic compound useful for preventing galvanic corrosion. The generation of fine intermetallic compounds reduces pinholes or the like penetrating the Al alloy film, resulting in improved alkali corrosion resistance. In addition, when a fine intermetallic compound useful for preventing galvanic corrosion is formed at the interface, the contact resistance between the oxide transparent conductive film and the Al alloy film can be kept low.

Thus, when an Al— (Ni / Co) —XZ alloy film containing a group Z element is used, the setting (adjustment) of the substrate temperature and the heating temperature depends on the amount of Ni in the Al alloy film and / or Alternatively, it is preferable to set not only the amount of Co but also the amount of element of group Z (single amount or total amount). This will be described in detail with reference to FIGS. 13 to 15 (containing Cu as an element of group Z) and FIGS. 16 to 18 (containing Ge as an element of group Z). As in FIGS. 10 to 12, in these figures, ◯ means that the alkali corrosion resistance is excellent, and ▲ means that the alkali corrosion resistance is inferior.

(Figures 13 to 15)
First, reference will be made to FIGS. Here, Al—x atomic% Ni—0.35 atomic% La—0.5 atomic% Cu alloy film [Ni content (x) is in the range of 0 to 3 atomic% as shown in FIGS. Is within. The relationship between the amount of Ni and the heating temperature is arranged for each substrate temperature specified in the above (1) to (3), and the influence of these on the alkali corrosion resistance is investigated. FIG. 13 shows the results when the substrate temperature is set to room temperature [corresponding to (1) above], and FIG. 14 shows the results when the substrate temperature is raised to 100 ° C. [above (2) FIG. 15 shows the result [equivalent to (3) above] when the film was formed with the substrate temperature further increased to 150 ° C. and 250 ° C.

In order to show the effect of addition of Cu, these FIGS. 13, 14, and 15 show the results (▲, ○) when using the Al alloy film, as well as FIGS. (Without Cu) are also shown side by side (▲, ○). In FIGS. 13 to 15, the two are shifted laterally so that they do not overlap. In the same Ni amount, ▲ and ○ on the right side are examples of addition of Cu, and ▲ and ○ on the left side are no addition of Cu. It is an example. Further, the size of the plot is also changed so that the difference between the two can be further understood. The case where the size of ▲ and ○ is large is an example of addition of Cu, and the case where the size of ▲ and ○ is small is an example of no addition of Cu. In FIG. 14 and FIG. 15, the results of adding 1 atom% of Ni and the results of adding 1 atom% of Ni as an example of adding Cu are added as examples in which Cu is not added.

From FIG. 13 to FIG. 15, the Al— (Ni / Co) —La alloy film described above was used when the Al—Ni—La—Cu alloy film further containing Cu of group Z was used as the Al alloy film. It was found that the same tendency was observed. In other words, when the substrate temperature is low, it is not possible to effectively prevent alkali corrosion unless the heating temperature is generally high, but when the substrate temperature is high, alkali corrosion can be suppressed even if the heating temperature is low. I understand. Moreover, the adjustment range of the substrate temperature and the heating temperature (for example, the heating temperature can be lowered when the substrate temperature is raised, the raising range of the substrate temperature and the lowering range of the heating temperature) is the amount of Ni in the Al alloy film or Cu It was also found that it was determined according to the amount.

Further, as apparent from the comparison of the results with and without Cu addition, the alkali corrosion resistance is further improved by the addition of Cu. Therefore, when the amount of Ni and the substrate temperature are the same, the preferable lower limit of the heating temperature is further increased. I also found that it can be lowered.

Specifically, first, the case where the Ni content in the Al alloy film is 2 atomic% in FIG. 13 (substrate temperature = room temperature) will be considered. When the substrate temperature is set to room temperature and the Al-2 atomic% Ni-0.35 atomic% La alloy film not containing Cu is used, it is preferable to control the heating temperature to approximately 250 ° C. or higher. When an Al-2 atomic% Ni-0.35 atomic% La-0.5 atomic% Cu alloy film containing Cu is used, the preferable lower limit of the heating temperature can be lowered, and the heating is generally performed at 150 ° C. or higher. Only the alkali corrosion resistance is improved. This same trend was seen when the Ni content was 3 atomic% and in all cases where the Ni content was 1 atomic%. Therefore, when the substrate temperature was set to room temperature, it was demonstrated that when the Cu-containing Al alloy film was used, the preferable lower limit of the heating temperature could be lowered as compared with the case where an Al alloy film not containing Cu was used.

FIG. 13 shows the results when the substrate temperature is set to room temperature. The same tendency is shown in FIGS. 14 (substrate temperature = 100 ° C.) and FIG. 15 (substrate temperature = 150) when the substrate temperature is changed. C. and 250.degree. C.).

From the above results, it can be inferred that not only the amount of Ni in the Al alloy film but also the amount of Cu contributes to the adjustment range of the substrate temperature and the heating temperature.

(About FIGS. 16 to 18)
Next, FIG. 16 to FIG. 18 (containing Ge as an element of group Z) will be considered.

Here, an Al-x atomic% Ni-0.2 atomic% La-0.5 atomic% Ge alloy film [Ni content (x) is in the range of 0 to 1 atomic% as shown in FIGS. And Ni = 0.2 atomic%, 0.5 atomic%, and 1 atomic%. The relationship between the amount of Ni and the heating temperature was arranged for each substrate temperature, and the influence of these on alkali corrosion resistance was investigated. FIG. 16 shows the results when the substrate temperature is set to room temperature [corresponding to the above (1)], and FIG. 17 shows the results when the substrate temperature is raised to 100 ° C. [above (2) FIG. 18 shows the result [equivalent to (3) above] when the film was formed with the substrate temperature further increased to 150 ° C. and 250 ° C.

In order to show the effect of addition of Ge, FIG. 16, FIG. 17 and FIG. 18 (all of which have Ge) are the same as those of FIGS. 0.35 atom%) results (▲, ○) are also shown side by side.
In FIGS. 16 to 18, the plots are laterally shifted so that they do not overlap. In the same amount of Ni, ▲ and ○ on the right side are examples of Ge addition, and ▲ and ○ on the left side are Ge. This is an additive-free example. Further, the size of the plot is also changed so that the difference between the two can be further understood. The case where the size of ▲ and ○ is large is an example of addition of Ge, and the case where the size of ▲ and ○ is small is an example of no addition of Ge. In addition to the plot of FIG. 10, in FIG. 16, the result when Ge was not added when the Ni amount was 0.2 atomic% and 0.5 atomic%, and the corresponding Ge addition. Results are also added. In FIG. 17, in addition to the plot of FIG. 11, the results when Ge is not added when the Ni content is 0.2 atomic% and 1 atomic%, and the results when Ge is added corresponding thereto are also added. ing. In FIG. 18, in addition to the plot of FIG. 12, the results when Ge is not added when the Ni content is 0.2 atomic% and 1 atomic%, and the results when Ge is added corresponding thereto are also added. ing. In FIGS. 16 to 18, only the results when the Ni content is between 0 and 1 atomic% are shown.

From FIG. 16 to FIG. 18, when the Al—Ni—La—Ge alloy film further containing Ge of group Z is used as the Al alloy film, the aforementioned Al—Ni—La alloy film (without Ge) was used. It turned out that the tendency similar to time is seen. In other words, when the substrate temperature is low, it is not possible to effectively prevent alkali corrosion unless the heating temperature is generally high, but when the substrate temperature is high, alkali corrosion can be suppressed even if the heating temperature is low. I understand. In addition, it has been found that the adjustment range of the substrate temperature and the heating temperature is determined according to the amount of Ni and the amount of Ge in the Al alloy film.

Further, as apparent from the comparison of the results with and without Ge addition, the alkali corrosion resistance is further improved by the addition of Ge. Therefore, when the amount of Ni and the substrate temperature are the same, the preferable lower limit of the heating temperature is further increased. I also found that it can be lowered. In particular, it has also been found that the addition effect of Ge tends to be exerted remarkably when the Ni content is a low concentration of about 1 atomic% or less, although it cannot be uniformly arranged.

Specifically, first, the case where the Ni content in the Al alloy film is 1 atomic% in FIG. 16 (substrate temperature = room temperature) will be considered. When the Al-1 atomic% Ni-0.2 atomic% La alloy film not containing Ge is used when the substrate temperature is room temperature, good alkali corrosion resistance can be obtained unless the heating temperature is set to 250 ° C. In contrast, when an Al-1 atomic% Ni-0.2 atomic% La-0.5 atomic% Ge alloy film containing Ge was used, it was resistant to alkali corrosion only by heating to 200 ° C or higher. Was found to improve. A similar tendency is seen when the Ni content in the Al alloy film is 0.5 atomic%, and when an Al-0.5 atomic% Ni-0.2 atomic% La alloy film not containing Ge is used. On the other hand, good alkali corrosion resistance was not obtained even when the heating temperature was set to 250 ° C., whereas Al-0.5 atomic% Ni-0.2 atomic% La-0.5 atomic% containing Ge When a Ge alloy film was used, the alkali corrosion resistance improved when heated to 250 ° C.

Next, in FIG. 17 (substrate temperature = 100 ° C.), the case where the amount of Ni in the Al alloy film is 1 atomic% will be considered. When the substrate temperature is 100 ° C. and an Al-1 atomic% Ni-0.2 atomic% La alloy film not containing Ge is used, good alkali corrosion resistance can be obtained unless the heating temperature is set to 200 ° C. In contrast, when an Al-1 atomic% Ni-0.2 atomic% La-0.5 atomic% Ge alloy film containing Ge was used, the alkali resistance was increased only by heating to 150 ° C. or higher. It was found that the corrosivity was improved. A similar tendency is observed when the Ni content is 0.5 atomic% and 0.2 atomic%. When using a Ge-containing Al alloy film, compared to using an Al alloy film not containing Ge. It has been found that the preferable lower limit of the heating temperature can be lowered.

Further, also in FIG. 18 (substrate temperatures = 150 ° C. and 250 ° C.), the effect of addition of Ge is observed when the Ni content is 1 atomic% and 0.2 atomic%, as described above. When used, it was found that the preferable lower limit of the heating temperature can be lowered as compared with the case where an Al alloy film not containing Ge is used.

Considering the results shown in FIGS. 16 to 18, (1) it is considered that the adjustment range of the substrate temperature and the heating temperature contributes not only to the Ni amount in the Al alloy film but also to the Ge amount. It was also found that the addition effect of Ge is slightly different depending on the amount of Ni and the substrate temperature, but generally, when the amount of Ni is a low concentration of about 1 atomic% or less, it tends to be noticeable in general.

The process for characterizing the present invention has been described above.

As described above, the present invention is characterized in that the substrate temperature and the heating temperature are appropriately controlled according to the amount of Ni and / or Co (including the amount of Z when an element of group Z is included). In addition, the film forming process other than the above is not particularly limited, and usually used means can be employed. Therefore, the first step of forming the oxide transparent conductive film on the substrate and the second step of forming the Al alloy film on the oxide transparent conductive film (excluding the substrate temperature) are appropriately performed using known methods. Select and use.

A typical example of the method for forming the Al alloy film is a sputtering method using a sputtering target. The sputtering method is to form a plasma discharge between a substrate and a sputtering target (target material) composed of the same kind of material as the thin film to be formed, and to make the gas ionized by the plasma discharge collide with the target material. In this method, atoms of the target material are knocked out and stacked on a substrate to produce a thin film. Unlike the vacuum evaporation method or the arc ion plating (AIP) method, the sputtering method has an advantage that a thin film having the same composition as the target material can be formed. In particular, an Al alloy film formed by a sputtering method has an advantage that it can dissolve an alloy element such as Nd that cannot be dissolved in an equilibrium state, and exhibits excellent performance as a thin film. However, the gist of the present invention is not limited to the above, and a method usually used for a method of forming an Al alloy film can be appropriately employed.

In the present invention, the order of patterning is not particularly limited. For example, the transparent oxide conductive film and the Al alloy film may be sequentially formed on the substrate by sputtering or the like, and then the transparent oxide conductive film and the Al alloy film may be patterned by lithography and etching. . Alternatively, an oxide transparent conductive film may be formed on the substrate and patterned, and then an Al alloy film may be formed and patterned.

Further, the ITO film constituting the oxide transparent conductive film is in an amorphous state before heating, and is dissolved in an etching solution for aluminum containing phosphoric acid as a main component. Therefore, there is selectivity with respect to the etching solution for aluminum. Therefore, when an Al alloy film is formed after the oxide transparent conductive film is patterned and etched, it is possible to prevent unnecessary etching of the already formed oxide transparent conductive film.

However, if the etching selectivity with Al is not required, an IZO film may be used as the oxide transparent conductive film. In addition to the ITO film, an oxide transparent conductive film having selectivity with an Al etchant can be used without any problem. The present invention does not limit the type of the oxide transparent conductive film.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and appropriate modifications are made within a range that can meet the above and the following purposes. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

Example 1
An ITO film (thickness: about 50 nm) containing about 10% by mass of SnO is sputtered on a substrate (non-alkali glass plate, thickness 0.7 mm, 4 inch size) as an oxide transparent conductive film (transparent pixel electrode). It formed by the method and patterned by photolithography. The sputtering conditions at this time are pressure: about 3 mTorr under an argon atmosphere.

On the ITO film patterned as described above, a pure Al film and an Al—Ni—La alloy film (hereinafter referred to as “Al-based alloy film”; film thickness: 100 nm) are formed as a reflective electrode by sputtering. Formed. The substrate temperature at the time of sputtering is as shown in Table 1 and Table 2 below, and the sputtering conditions are pressure: about 2 mTorr under an argon atmosphere.

Next, heat treatment was performed for 30 minutes at the heating temperatures shown in Tables 1 and 2 under a nitrogen atmosphere. For comparison, an unheated product was also prepared. Then, after apply | coating a resist to Al type alloy film and exposing, it developed by being immersed in 2.38 mass% TMAH aqueous solution (20 degreeC) for 1 minute. In this embodiment, the heat treatment is performed in a nitrogen atmosphere. However, the heat treatment is not limited thereto, and is performed in a known atmosphere condition (for example, in a vacuum atmosphere with a degree of vacuum of about 3 × 10 ⁻⁴ Pa). May be.

(Alkaline corrosion resistance)
Alkaline corrosivity of each Al-based alloy film was evaluated by measuring the potential difference with a voltmeter by short-circuiting the electrode of the Al-based alloy film to be measured and the silver-silver chloride reference electrode in the above TMAH aqueous solution. . For comparison, the electrode potential of the poly-ITO film was also measured. In this example, as shown in FIGS. 7 to 8 to be described later, no corrosion was observed when the optical microscope observation and the transmission electron microscope observation after immersion in the THAH aqueous solution were performed, and the electrode potential difference from amorphous ITO was not observed. Those satisfying 1.55 V or less were evaluated as ◯ (excellent in alkali corrosion resistance), and those not satisfying any of the above requirements were evaluated as x (inferior in alkali corrosion resistance).

(Contact resistance)
The contact resistance when the Al-based alloy film and the ITO film were directly connected was measured by a four-terminal method using the Kelvin pattern (contact hole size, 20, 40, and 80 μm square) shown in FIG. The contact resistance was examined by passing a current between the Al-based alloy film and the ITO film and measuring the voltage drop between the ITO-Al alloy at another terminal. Specifically, by passing the current I between I _{1 and} I ₂ in FIG. 9 and monitoring the voltage V between V _{1 and} V ₂ , the contact resistance R of the contact portion C is set to [R = (V ₁ − V ₂ ) / I ₂ ]. In this example, a contact resistance of 1500 Ω / cm ² or less was evaluated as having a low contact resistance (pass).

Further, the content of the alloy element in the Al-based alloy film was determined by an ICP emission analysis (inductively coupled plasma emission analysis) method.

These results are shown in Tables 1 and 2. In Table 1, No. 1 (pure Al film) and No. 1 Table 3 shows the results of the electrode potentials measured for 19 (Al-2 atom% Ni-0.35 atom% La) as described above.

As is apparent from the results in Tables 1 and 2, Al-based alloy films (Nos. 5, 6, 8 to 10, 12 to 14, 16 to 18, 23, 26 in Table 1) produced by the method of the present invention were used. 27, 29-31, 33-35, No. 40, 45, 48, 49, 52, 53) in Table 2 are all excellent in alkali corrosion resistance, and are composed of an Al alloy film and an ITO film. The contact resistance value is also low.

Also, from Table 3, it was found that the electrode potential difference with the ITO film can be suppressed to a smaller value when using the Al—Ni—X alloy film used in the present invention as compared with pure Al (No. 1).

For reference, an Al-2 atomic% Ni-0.35 atomic% La alloy was used and the substrate temperature was changed from room temperature to no heating. No. 19 (Comparative Example) and the same alloy, the substrate temperature was changed from room temperature to 250 ° C. The corrosion status of No. 23 (Example of the present invention) is shown in FIGS. In detail, FIG. 5 and FIG. 19 is an optical microscope photograph and a transmission electron microscope cross-sectional photograph after immersion in a TMAH aqueous solution (FE-TEM, Hitachi, Ltd., model name: “HF2000” is used). 7 and 8 show sample Nos. 23 is an optical microscope photograph and a transmission electron microscope cross-sectional photograph after immersion in a TMAH aqueous solution. In observation with a transmission electron microscope, the film composition was identified by electron excitation X-ray analysis.

As is clear from comparison of these figures, the sample No. that was not heated was used. In No. 19, corrosion due to TMAH immersion was observed (see FIGS. 5 and 6), while sample No. No corrosion was observed with 23 (see FIGS. 7 and 8).

Furthermore, the influence of the Ni content in the Al alloy film on the reflectance was investigated.

Specifically, an Al alloy of Al-x atomic% Ni-0.35 atomic% La (x is 1 to 5.5 atomic%) is used, the substrate temperature during film formation is set to room temperature, and heating after film formation is performed. The reflectance of the sample formed by controlling the temperature to about 250 ° C. and the heating time to about 30 minutes was measured. The reflectance was measured using a visible / ultraviolet spectrophotometer “V-570” manufactured by JASCO Corporation in the measurement wavelength range of 1000 to 250 nm. Specifically, the value obtained by measuring the reflected light height of the sample with respect to the reflected light intensity of the reference mirror was defined as “spectral reflectance”.

FIG. 4 is a graph showing the change in reflectance (wavelength: 850 to 250 nm) of each sample. When the reflectance at 550 nm is taken as a reference, a high reflectance of about 88% to 92% was obtained in a sample satisfying the range of the present invention with an Ni amount of 1 to 4 atomic%, whereas In the sample where the amount of Ni exceeds 5.5 atomic% and exceeds the range of the present invention, the reflectance is reduced to approximately 84%.

Although this application has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on December 26, 2007 (Japanese Patent Application No. 2007-335004) and a Japanese patent application filed on December 19, 2008 (Japanese Patent Application No. 2008-324374). Incorporated herein by reference.

The present invention relates to a method for manufacturing a display device represented by a liquid crystal display, an organic electroluminescence (EL) display, or the like. Specifically, the present invention relates to a method for manufacturing a display device having a structure in which an oxide transparent conductive film and an Al alloy film for a reflective electrode are directly connected, and alkaline corrosion during patterning of the Al alloy film. The present invention relates to a method for manufacturing a display device that can effectively prevent the above. According to the present invention, the thermal history (specifically, the substrate temperature at the time of film formation and the heating temperature after the film formation) of the Al alloy film as the reflective electrode is determined according to the amount of Ni and / or Co contained in the Al alloy film. Therefore, even when immersed in an alkaline developer such as TMAH aqueous solution during patterning, corrosion of the Al alloy film is suppressed, and the contact resistance between the transparent oxide conductive film and the Al alloy film is reduced. can do.

Claims

A manufacturing method of a display device comprising a structure in which an Al alloy film for a reflective electrode is directly connected on an oxide transparent conductive film,
A first step of forming the oxide transparent conductive film on a substrate;
A second step of forming the Al alloy film on the oxide transparent conductive film;
A third step of heating the Al alloy film,
The Al alloy film contains at least one of Ni and Co in an amount of 0.1 to 4 atomic% and at least one element selected from Group X in a total amount of 0.1 to 2 atomic%. -(Ni / Co) -X alloy, wherein X is La, Mg, Cr, Mn, Ru, Rh, Pt, Pd, Ir, Ce, Pr, Gd, Tb, Dy, Nd, Ti, Zr, Nb, Mo, Hf, Ta, W, Y, Fe, Sm, Eu, Ho, Er, Tm, Yb, and Lu,
The substrate temperature in the second step and the heating temperature in the third step are controlled in accordance with at least one of the Ni content and the Co content of the Al— (Ni / Co) —X alloy film. ,
A manufacturing method of a display device characterized by the above.
The method for manufacturing a display device according to claim 1, wherein the Al alloy film contains 0.5 to 4 atomic% of at least one of Ni and Co.
The method for manufacturing a display device according to claim 1, wherein the Al alloy film contains 0.5 to 4 atomic% of Ni.
The Al— (Ni / Co) —X alloy film contains at least one of 0.1 to 4 atomic% of Ni and Co and at least one of 0.1 to 2 atomic% of La and Nd The method for manufacturing a display device according to any one of claims 1 to 3.
The Al— (Ni / Co) —X alloy film further contains 0.1 to 2 atomic% of Z (Z is at least one element selected from the group consisting of Ge, Cu, and Si). The method for producing a display device according to any one of claims 1 to 3, further comprising:
The Al— (Ni / Co) —X alloy film comprises at least one of 0.1 to 4 atomic% of Ni and Co, at least one of 0.1 to 2 atomic% of La and Nd, and The method for manufacturing a display device according to claim 5, comprising at least one of 1 to 2 atomic% of Ge and Cu.
The method for manufacturing a display device according to claim 1, wherein the transparent oxide conductive film is indium tin oxide (ITO) or indium zinc oxide (IZO).