JP4763568B2 - Transistor substrate - Google Patents

Description

  The present invention relates to a wiring or an electrode provided on a substrate, and particularly relates to a gate wiring or a gate electrode connected to a transistor. The wiring or electrode of the present invention is suitably used for display devices such as liquid crystal display devices and EL devices.

  Liquid crystal display devices used in various fields ranging from small mobile phones to large televisions exceeding 30 inches can be divided into simple matrix liquid crystal display devices and active matrix liquid crystal display devices depending on the pixel driving method. . Among them, an active matrix liquid crystal display device having a thin film transistor (hereinafter referred to as TFT) as a switching element is widely used because it can realize high-precision image quality and can cope with high-speed images. .

  With reference to FIG. 1, the configuration and operation principle of a typical liquid crystal panel applied to an active matrix liquid crystal display device will be described. Here, an example of a TFT substrate using hydrogen amorphous silicon as an active semiconductor layer (hereinafter sometimes referred to as an amorphous silicon TFT substrate) will be described.

As shown in FIG. 1, a liquid crystal panel 100 is disposed between a TFT substrate 1, a counter substrate 2 disposed to face the TFT substrate 1, and between the TFT substrate 1 and the counter substrate 2, and serves as a light modulation layer. And a functioning liquid crystal layer 3. The TFT substrate 1 has a TFT 4 disposed on an insulating glass substrate 1a, a transparent pixel electrode 5, and a wiring portion 6 including a scanning line and a signal line. The transparent pixel electrode 5 is formed of an indium tin oxide (ITO) film containing about 10% by mass of tin oxide (SnO) in indium oxide (In ₂ O ₃ ).

  In the liquid crystal panel 100, the alignment direction of liquid crystal molecules in the liquid crystal layer 3 is controlled by an electric field formed between the counter electrode 2 and the transparent pixel electrode 5, and light passing through the liquid crystal layer 3 is modulated. As a result, the amount of light transmitted through the counter substrate 2 is controlled to display an image.

  Next, the configuration and operation principle of a conventional amorphous silicon TFT substrate suitably used for a liquid crystal panel will be described in detail with reference to FIG. FIG. 2 is an enlarged view of a main part A in FIG. FIG. 2 shows an example of a bottom gate type.

  As shown in FIG. 2, a scanning line (gate thin film wiring) 25 is formed on a glass substrate (not shown), and a part of the scanning line 25 functions as a gate electrode 26 for controlling on / off of the TFT. To do. A gate insulating film (Si nitride film) 27 is formed so as to cover the gate electrode 26. A signal line (source-drain wiring) 34 is formed so as to intersect the scanning line 25 via the gate insulating film 27, and a part of the signal line 34 functions as a source electrode 28 of the TFT. On the gate insulating film 27, an amorphous silicon channel film (active semiconductor film) 33, a signal line (source-drain wiring) 34, and an interlayer insulating Si nitride film (protective film) 30 are sequentially formed.

The amorphous silicon channel film 33 includes a doped layer (n layer) doped with P (phosphorus) and an intrinsic layer (also referred to as i layer or non-doped layer) not doped with P. In the pixel region on the gate insulating film 27, for example, the transparent pixel electrode 5 formed of an ITO film containing SnO in In ₂ O ₃ is disposed. The drain electrode 29 of the TFT is in direct contact with and electrically connected to the transparent pixel electrode 5.

  When the gate voltage is supplied to the gate electrode 26 via the scanning line 25, the TFT 4 is turned on, and the drive voltage supplied in advance to the signal line 34 is transmitted from the source electrode 28 via the drain electrode 29 to the transparent pixel electrode. 5 is supplied. When a driving voltage of a predetermined level is supplied to the transparent pixel electrode 5, as described with reference to FIG. 1, a potential difference is generated between the transparent pixel electrode 5 and the counter electrode 2. As a result, the liquid crystal contained in the liquid crystal layer 3. The molecules are aligned and light modulation is performed.

  In the TFT substrate 1, the source-drain wiring 34 electrically connected to the source-drain electrode, the signal line (pixel electrode signal line) electrically connected to the transparent pixel electrode 5, and the gate electrode 26 are electrically connected. The scanning lines 25 to be connected are both low in specific resistance and easy to process, and are all aluminum alloys such as pure Al or Al—Nd (hereinafter collectively referred to as Al-based alloys). A barrier metal layer (not shown) made of a refractory metal such as Mo, Cr, Ti, W or the like is formed above or below the thin film. Typically, for example, a Mo layer (lower barrier metal layer) having a thickness of about 50 nm, a pure Al or Al—Nd alloy thin film having a thickness of about 150 nm, and a Mo layer (upper barrier metal layer) having a thickness of about 50 nm are included. A laminated wiring having a three-layer structure formed sequentially is exemplified.

  The reason for providing such a barrier metal layer between, for example, the transparent pixel electrode 5 and the Al-based alloy thin film is that when the Al-based alloy thin film is directly connected to the transparent pixel electrode, the contact resistance increases, and the display quality of the screen is improved. It is because it falls. Since Al used as a wiring material for transparent pixel electrodes is very easily oxidized, oxygen at the interface between the Al-based alloy thin film and the transparent pixel electrode is caused by oxygen generated during the film formation process of the liquid crystal panel or oxygen added during film formation. An oxide insulating layer is formed. Moreover, although ITO of the transparent pixel electrode material is a conductive metal oxide, when an Al oxide layer is generated as described above, an electrical ohmic connection cannot be performed.

  However, in order to form these barrier metal layers, a film forming apparatus for forming a barrier metal is additionally required in addition to a film forming apparatus for forming an Al-based alloy wiring. Specifically, since it is necessary to use a film forming apparatus (typically a cluster tool in which a plurality of film forming chambers are connected to a transfer chamber) each equipped with an extra film forming chamber for forming a barrier metal, This causes an increase in manufacturing cost and a decrease in productivity.

  Also, since the metal used as the barrier metal layer and pure Al or aluminum alloy have different processing speeds in processing steps such as wet etching using chemicals, the lateral processing dimensions in the processing steps can be controlled. It becomes extremely difficult. Therefore, the formation of the barrier layer leads to a complicated process not only from the viewpoint of film formation but also from the viewpoint of processing, resulting in an increase in manufacturing cost and a decrease in productivity.

  Therefore, various wiring materials that can omit the formation of the barrier metal layer (hereinafter may be referred to as direct contact wiring materials) have been proposed, and the applicant of the present application also disclosed in Patent Documents 1 to 3, for example. The materials described are proposed.

  Among these, Patent Document 1 discloses at least an aluminum alloy film selected from the group consisting of Au, Ag, Zn, Cu, Ni, Sr, Sm, Ge, and Bi as a material that can be directly connected to the pixel electrode. An aluminum alloy thin containing a total of 0.1 to 6 atomic% of one kind of alloy element is disclosed. At the interface between the aluminum alloy film and the pixel electrode, a part or all of the alloy elements constituting the aluminum alloy film are present as precipitates or concentrated layers, and a region having a low electrical resistance is partially or entirely. As a result, the contact resistance between the aluminum alloy film and the pixel electrode is greatly reduced. Therefore, even if the barrier layer is omitted, a liquid crystal display device having a high display quality can be obtained.

  In Patent Document 2, an aluminum alloy film can be directly connected to a pixel electrode, and at least Ni is used as an alloy component as a material having chemical resistance, particularly excellent resistance to an alkaline developer or stripping solution. An aluminum alloy multilayer film in which a nitrogen-containing aluminum alloy film (second layer) is formed on top of an aluminum alloy film (first layer) containing 0.1 to 6 atomic% is disclosed. The nitrogen-containing aluminum alloy film of the second layer has an effect of improving the corrosion resistance against the alkaline solution. Further, in the region where the pixel electrode and the aluminum alloy multilayer film are in contact with each other, the second layer nitrogen-containing aluminum alloy film does not exist, and only the first layer Al-Ni alloy film having a low resistance value exists. The contact resistance between the aluminum alloy film and the pixel electrode can be kept low.

  Patent Document 3 discloses at least one selected from the group consisting of Au, Ag, Zn, Cu, Ni, Sr, Sm, Ge, and Bi as another material capable of directly connecting an aluminum alloy film to a pixel electrode. An oxide film of the aluminum alloy is formed at the interface between the aluminum alloy film containing 0.1 to 6 atomic percent of one kind of alloy element in total and the pixel electrode, and the thickness and oxygen content of the oxide film are appropriate. Controlled materials are disclosed. According to this method, since the electrical resistivity of the aluminum oxide layer formed at the interface between the pixel electrode and the aluminum alloy film is reduced and the conductivity is increased, the contact resistance between the aluminum alloy film and the pixel electrode is kept low. It is done.

The wiring materials described in Patent Documents 1 to 3 described above can be applied as a material constituting a scanning line or a signal line, and function as a gate electrode or a source-drain electrode.
JP 2004-214606 A JP 2005-303003 A JP 2006-23388 A

  However, when the above-described direct contact wiring material is used and, for example, the gate wiring film 26 is formed on the substrate, pinholes are generated in the gate wiring film 26, but the results of the subsequent studies by the present inventors. It became clear.

  As a cause of occurrence of pinholes, for example, corrosion of an aluminum alloy thin film by a photoresist stripping solution used in a photolithography process can be considered. As will be described in detail later, the gate wiring film 26 is formed by forming a predetermined aluminum alloy film on the glass substrate 1a by a sputtering method and then patterning the film by, for example, photolithography and wet etching. In the photolithography process, after patterning the photoresist film on the aluminum alloy film, for example, the photoresist film is removed with a stripping solution containing an amine-based material, but the stripping solution slightly remaining on the surface of the aluminum alloy thin film is, When mixed with water in the subsequent washing step, it becomes alkaline, so the aluminum alloy thin film is considered to be locally etched (corroded).

  In particular, all of the above-described wiring materials for direct contact use an Al—Ni alloy containing Ni, which is a metal nobler than Al, as an alloy component, so that the corrosion rate against an alkaline solution is larger than that of pure Al. Become. The main cause is that when an Al—Ni alloy is used, a dense and highly corrosion-resistant passive film like that of pure Al is hardly formed on the surface, and the anticorrosion performance (alkali resistance) against an alkaline solution is lowered. Conceivable.

  In the case of the bottom gate type TFT substrate shown in FIG. 2, the influence on the TFT characteristics when a pinhole is generated in the gate wiring film 26 in contact with the glass substrate and reaches the interface with the glass substrate 1a will be considered.

  As is well known, the TFT has a function of turning on and off the current flowing between the source electrode 28 and the drain electrode 29 in accordance with a signal from the gate electrode 26. However, when a pinhole is generated in the gate wiring film 26, the backlight light that passes upward from the lower side of the glass substrate 1a directly passes through the gate insulating film 27 without passing through the gate wiring film 26, and then the TFT light. The channel layer 33 is directly irradiated. When the channel layer 30 is irradiated with light, electron / hole pairs are generated and move to the positive electrode and the negative electrode, respectively, so that a weak current (leakage current) always flows. Function declines. As a result, ON / OFF of the pixel corresponding to the TFT becomes unclear, and the quality of the liquid crystal display device is deteriorated.

  In the above description, the liquid crystal display device has been taken up as a representative. However, the above-described problem is not limited to the liquid crystal display device, and is common to amorphous silicon TFT substrates. In addition, the above-mentioned problem is also observed in a TFT substrate using polycrystalline silicon in addition to amorphous silicon as a TFT semiconductor layer.

  The present invention has been made in view of the above circumstances, and an object thereof is a wiring material formed on a substrate, and preferably a wiring capable of directly contacting an aluminum alloy thin film and a pixel electrode. An object of the present invention is to provide a wiring material excellent in alkali resistance.

  More specifically, the object of the present invention is to prevent degradation of TFT characteristics due to light leakage from a pinhole even if a defect such as a pinhole occurs in a wiring film (electrode) formed on a substrate. An object of the present invention is to provide a wiring material (electrode material) that can be used.

  The wiring or electrode of the present invention that has solved the above problems is a wiring or electrode provided on a substrate, and the wiring or the electrode is a first of a nitrogen-containing aluminum alloy in order from the substrate side. It has a laminated structure consisting of a thin film and a second thin film of an aluminum alloy, and the content of nitrogen contained in the first thin film is 13 atomic% to 50 atomic%. is doing.

  Another wiring or electrode of the present invention that has solved the above problem is a wiring or electrode provided on a substrate, and the wiring is a first of nitrogen / oxygen-containing aluminum alloy in order from the substrate side. And a second thin film made of an aluminum alloy, the ratio of nitrogen contained in the first thin film is 13 atomic% to 50 atomic%, and the ratio of oxygen is It is summarized that it is 10 atomic% or less.

  In a preferred embodiment, the thickness of the first thin film is in the range of 10 nm to 100 nm.

  In a preferred embodiment, the aluminum alloy constituting the first thin film and the second thin film is the same or different and at least selected from the group consisting of Ni, Ag, Zn, Cu, and Ge as an alloy component One kind of element is contained in the range of 0.1 atomic% to 6 atomic%.

  In a preferred embodiment, the wiring or the electrode is connected to a transistor (more preferably, a thin film transistor).

  In a preferred embodiment, the wiring or the electrode is a gate wiring or a gate electrode.

  A method for producing a wiring or an electrode according to any one of the above methods includes: forming a first thin film of a nitrogen-containing aluminum alloy or a nitrogen / oxygen-containing aluminum alloy on a substrate with an inert gas and a nitrogen gas, or an inert gas; The method includes a step of vapor-depositing by a reactive sputtering method using a mixed gas of nitrogen gas and oxygen gas, and a step of vapor-depositing a second thin film of an aluminum alloy by a sputtering method.

  The present invention also includes a transistor substrate (preferably a thin film transistor substrate) provided with any of the wirings or electrodes described above.

  The present invention also includes a display device including the above-described transistor substrate.

  According to the present invention, a nitrogen-containing aluminum alloy thin film or a nitrogen / oxygen-containing aluminum alloy thin film excellent in alkali resistance is formed between the substrate and the aluminum alloy thin film. It is very useful in that it can eliminate the problems (defects such as pinholes and associated TFT degradation) that Al-Ni alloys proposed for direct contact wiring or electrodes can handle. .

  The inventor has intensively studied in order to provide a wiring or electrode in which the alkali resistance of a wiring or electrode made of an aluminum alloy provided on a substrate is enhanced and pinholes can be prevented from occurring. As a result, the inventors have found that the intended purpose can be achieved by providing a predetermined nitrogen-containing aluminum alloy thin film or a nitrogen / oxygen-containing aluminum alloy thin film between the substrate and the aluminum alloy thin film, thereby completing the present invention.

  The wiring or electrode of the present invention is particularly preferably used for a gate wiring or a gate electrode connected to a transistor such as a thin film transistor.

  The effect of the present invention (the effect of improving the alkali resistance of the wiring or electrode formed on the substrate) is, for example, a direct contact that can be directly connected to the pixel electrode disclosed in Patent Documents 1 to 3 described above. In particular, when an aluminum alloy wiring that is inferior in alkali resistance as compared with pure aluminum, such as a wiring for use or an electrode (specifically, for example, an Al—Ni alloy), it is remarkably exhibited. For example, when an Al—Ni alloy is formed on a substrate and wirings or electrodes are formed, defects such as pinholes may occur and the TFT characteristics may deteriorate. If a predetermined nitrogen-containing aluminum alloy film or a nitrogen / oxygen-containing aluminum alloy film is interposed between the Ni alloy film and the Al-Ni alloy, defects such as pinholes do not occur, and the TFT There is no deterioration in properties. Even if pinholes occur in the above Al-Ni alloy, the TFT characteristics deteriorate due to the formation of a nitrogen-containing aluminum alloy film or nitrogen / oxygen-containing aluminum alloy film with excellent alkali resistance on the substrate. Is suppressed. Therefore, generation of current (leakage current) due to leakage of backlight light can be prevented, and degradation of TFT characteristics can be effectively suppressed. Therefore, according to the present invention, it is possible to realize a high-quality display device that can be directly connected to the pixel electrode and sufficiently suppress the deterioration of TFT characteristics.

  However, it goes without saying that the lamination technique of the present invention is not limited to the above-described embodiment, and can be applied to all gate electrodes formed on a glass substrate.

  Hereinafter, an embodiment of a wiring or an electrode according to the present invention will be described with reference to FIG. Hereinafter, for convenience of explanation, the wiring or the electrode may be simply referred to as “wiring”.

  FIG. 3 schematically shows a part of a bottom gate TFT substrate in which a gate wiring is provided on the substrate.

  As shown in FIG. 3, the gate wiring 56 has a laminated structure including a first thin film 52 of a nitrogen-containing aluminum alloy and a second thin film 53 of an aluminum alloy in this order from the substrate 51 side.

  The first thin film 52 characterizing the present invention is made of an aluminum nitride alloy nitrogen-containing aluminum alloy, and the nitrogen content in the nitrogen-containing aluminum alloy is 13 atomic% or more. Here, the “nitrogen content” means the nitrogen concentration at the interface between the substrate 51 and the first thin film 52 (the portion where the nitrogen content is highest). As will be described in detail later, the first thin film 52 is deposited on the substrate 51 by a sputtering method (reactive sputtering method) using a mixed gas of an inert gas such as Ar gas and nitrogen gas as a reactive gas. Therefore, the first thin film 52 has a concentration gradient in which the nitrogen content decreases from the substrate 51 side toward the second thin film 53, and the substrate 51, the first thin film 52, On the other hand, the nitrogen-containing layer is the largest at the interface, while the nitrogen-containing layer is substantially 0 (zero) at the interface between the first thin film 52 and the second thin film 53. According to the experiments of the present inventors, it was found that if the maximum nitrogen concentration at the interface where the nitrogen content is highest is controlled to 13 atomic% or more, the desired alkali resistance is effectively exhibited. . From the viewpoint of improving alkali resistance, the higher the nitrogen content, the better. For example, it is preferably 28 atomic% or more, and more preferably 38 atomic% or more. In the case of the aluminum nitride alloy layer, the stoichiometry (constant composition ratio) of Al and N is Al: N = 1: 1, so the upper limit of the nitrogen content is about 50 atomic%.

  Alternatively, the first thin film 52 may be made of a nitrogen / oxygen-containing aluminum alloy. In this case, the first thin film 52 is made of an aluminum nitride alloy, an aluminum oxide alloy, an aluminum oxynitride alloy, or the like. Similarly to the above, the nitrogen content in the nitrogen / oxygen-containing aluminum alloy is 13 atomic% or more, and the oxygen content is preferably 0.02 atomic% or more. The action of improving alkali resistance is superior to aluminum nitride containing nitrogen rather than aluminum oxide containing oxygen.

  The nitrogen content in the nitrogen / oxygen-containing aluminum alloy is the same as the nitrogen-containing layer in the nitrogen-containing aluminum alloy layer described above, and the description thereof is omitted.

  The “oxygen content” in the nitrogen / oxygen-containing aluminum alloy means the oxygen concentration at the interface between the substrate 51 and the first thin film 52 (the portion where the oxygen content is highest). As will be described in detail later, the first thin film 52 is formed on the substrate by a sputtering method (reactive sputtering method) using a mixed gas of an inert gas such as Ar gas, nitrogen gas, and oxygen gas as a reactive gas. Since the first thin film 52 has a concentration gradient in which the oxygen content decreases from the substrate 51 toward the second thin film 53, the first thin film 52 and the first thin film 52 have a concentration gradient. The oxygen-containing layer is the most at the interface with the thin film 52, while the oxygen-containing layer is substantially 0 (zero) at the interface between the first thin film 52 and the second thin film 53. According to the experiments by the present inventors, it has been found that the maximum concentration of oxygen at the above-mentioned interface where the oxygen content is the highest may be included in about 10 atomic%. From the viewpoint of improving alkali resistance, the lower the oxygen content, the better. For example, it is preferably 5 atomic% or less, more preferably 2 atomic% or less.

  As described above, the first thin film 52 is composed of either a nitrogen-containing aluminum alloy containing only nitrogen or a nitrogen / oxygen-containing aluminum alloy containing both nitrogen and oxygen as described above. It is not composed of an oxygen-containing aluminum alloy containing only oxygen. This is because aluminum oxide containing oxygen is transparent as a bulk material and cannot effectively prevent transmission of backlight light. On the other hand, if a thin film made of nitrogen / oxygen-containing aluminum in which both nitrogen and oxygen are mixed is provided, the aluminum oxide will be in the form of fine particles, reflecting or scattering the backlight light, and suppressing the transmission of the backlight light. Conceivable.

  The nitrogen content and the oxygen content in the first thin film 52 were measured using Al (2p), N (1 s), and the depth direction of the film while etching the thin film using an XPS (fluorescence X-ray analyzer). The content of Al, N, and O in the film was measured by analyzing the strength of O (1s). The amount of Al in the film was also measured in order to confirm whether nitrogen and oxygen were bonded to Al.

  The thickness of the first thin film 52 is preferably in the range of 10 nm to 100 nm. Thereby, even if all of the second aluminum alloy thin film 52 is etched and removed in the photolithography process, the transmittance of the backlight light (usually green having a wavelength of 550 nm) to the first thin film 52 is substantially increased. Thus, the leakage current due to the leakage of the backlight light can be surely prevented.

  In order to effectively exhibit the above action, the thickness of the first thin film 52 is set to 10 nm or more. However, when the thickness of the first thin film 52 exceeds 100 nm, the electrical resistivity of the laminated aluminum alloy including the second thin film 53 increases. Considering these comprehensively, the thickness of the first thin film 52 is more preferably in the range of 20 nm to 70 nm.

  The second thin film 53 is made of an aluminum alloy and does not substantially contain nitrogen and oxygen. Here, “substantially does not contain” means that nitrogen and oxygen at a level that can be unavoidably included in the process of forming a thin film described later can be tolerated. Therefore, the content of nitrogen and oxygen is not necessarily 0 atomic%, and a level that does not hinder the action of the present invention, for example, about 200 ppm atomic% of nitrogen or about 200 ppm atomic% of oxygen may be included. .

  As an aluminum alloy which comprises the 1st thin film 52 and the 2nd thin film 53, the thing of the composition as described in patent document 1-patent document 3 mentioned above is used suitably, for example. By using these aluminum alloys, it is possible to prevent deterioration of TFT characteristics due to pinholes and the like, and it is possible to provide a wiring or an electrode that can be directly connected to the pixel electrode.

  The aluminum alloy constituting the gate wiring and the aluminum alloy constituting the source-drain wiring may be of the same composition. Thereby, the manufacturing process can be simplified.

  Specifically, the aluminum alloys constituting the first thin film 52 and the second thin film 53 are preferably the same or different and have the following compositions (1) to (4).

(1) Al-α alloy containing at least one element belonging to group α in the range of 0.1 atomic% to 6 atomic%, where group α is composed of Ni, Ag, Zn, Cu, and Ge Is done.

  Elements belonging to group α are useful for reducing electrical resistivity. When these elements are added singly or in combination into Al within the above range, at least one of the elements belonging to α at the connection interface between the Al alloy thin film and the transparent pixel electrode at a relatively low heat treatment temperature. For example, the electrical resistivity after heat treatment at 250 ° C. for 30 minutes is generally reduced to 7 Ω · cm or less. can do.

  Among the above elements, Ni is particularly excellent in the effect of reducing electrical resistivity and heat resistance, so it is preferable to use at least an Al—Ni alloy containing Ni.

  If the element belonging to the group α is less than 0.1 atomic%, the formation of a desired α-containing concentrated layer is insufficient, and the connection resistance cannot be suppressed sufficiently low. However, if the content of the element belonging to group α exceeds 6 atomic%, the electrical resistivity of the Al-based alloy thin film itself is increased, the response speed of the pixel is decreased, the power consumption is increased, and the display quality is improved. It falls and cannot be put to practical use. The content of an element belonging to the group α is preferably 0.5 atomic% or more and 5 atomic% or less.

(2) Al—Ni—Q alloy containing at least 0.1 atomic% of Ni and containing at least one element belonging to group Q in the following range: 0.1 atomic% ≦ [Ni] + 10 × [Q] ≦ 6 atomic%
In the formula, [Ni] means the Ni content (atomic%),
[Q] means the content (atomic%) of elements belonging to Group Q.
Here, the group Q is composed of Nd, Y, Fe, and Co. These elements may be added alone or in combination of two or more. When two or more elements are added, the total content of each element only needs to satisfy the above range.

  The Al—Ni—Q alloy is a ternary alloy containing Ni as an element belonging to the group α described above and further containing an element belonging to the group Q as a third component.

  By using an Al—Ni—Q alloy containing an element belonging to group Q, the heat resistance is remarkably enhanced, and the formation of hillocks (cove-like projections) on the surface of the Al-based alloy thin film can be effectively prevented. . The content [Q] of elements belonging to the group Q is appropriately determined in relation to the Ni content [Ni] as shown in the above formula. In the above formula, when the value represented by {[Ni] + 10 × [Q]} is the II value, when the II value falls below the left side (0.1 atomic%) of the above formula, the above-described action is effectively exhibited. On the other hand, when the II value exceeds the right side (6 atomic%) of the above formula, the above-described effect is improved, but the electrical resistivity of the film material is increased. Considering these two aspects, the II value is more preferably 0.2 atomic% or more and 5 atomic% or less.

(3) Al—Ni—Z alloy containing at least 0.1 atomic% or more of Ni and an element belonging to group Z in the following range: 0.1 atomic% ≦ [Ni] + 15 × [Z] ≦ 6 atoms %
In the formula, [Ni] means the Ni content (atomic%),
[Z] means the content (atomic%) of an element belonging to group Z.
Here, the group Z is composed of Ti, V, Zr, Nb, Mo, Hf, Ta, and W. These elements may be added alone or in combination of two or more. When two or more elements are added, the total content of each element only needs to satisfy the above range.

  The Al—Ni—Z alloy is a ternary alloy containing Ni as an element belonging to the group α described above and further containing an element belonging to the group Z as a third component.

  By using an Al—Ni—Z alloy containing an element belonging to group Z, the heat resistance is remarkably enhanced, and the formation of hillocks (cove-like projections) on the surface of the Al-based alloy thin film can be effectively prevented. . The content [Z] of the element belonging to the group Z is appropriately determined in relation to the Ni content [Ni] as shown in the above formula. In the above formula, when the value represented by {[Ni] + 15 × [Z]} is the III value, when the III value is less than the left side (0.1 atomic%) of the above formula, the above-described action is effectively exhibited. On the other hand, when the III value exceeds the right side (6 atomic%) of the above formula, the above-described effect is improved, but the electrical resistivity of the film material is increased. Considering these two aspects, the III value is more preferably 0.2 atomic% or more and 5 atomic% or less.

(4) Al-Ni-X alloy containing at least 0.1 atomic% or more of Ni and an element belonging to group X in the following range: 0.1 atomic% ≦ [Ni] + 5 × [X] ≦ 6 atoms %
In the formula, [Ni] means the Ni content (atomic%),
[X] means the content (atomic%) of an element belonging to Group X.
Here, the group X includes Mg, Cr, Mn, Ru, Rh, Pd, Ir, Pt, La, Ce, Pr, Gd, Tb, Sm, Eu, Ho, Er, Tm, Yb, Lu, and Dy. Composed. These elements may be added alone or in combination of two or more. When two or more elements are added, the total content of each element only needs to satisfy the above range.

  By using an Al—Ni—X alloy containing an element belonging to group X, the heat resistance is remarkably enhanced, and the formation of hillocks (cove-like projections) on the surface of the Al-based alloy thin film can be effectively prevented. . The content [X] of the element belonging to the group X is appropriately determined in relation to the Ni content [Ni] as shown in the above formula. In the above formula, when the value represented by {[Ni] + 5 × [X]} is an IV value, when the IV value is lower than the left side (0.1 atomic%) of the above formula, the above-described action is effectively exhibited. On the other hand, when the IV value exceeds the right side (6 atomic%) of the above formula, the above-described effect is improved, but the electrical resistivity of the film material is increased. Considering these two aspects, the IV value is more preferably 0.2 atomic% or more and 5 atomic% or less.

  In addition to the above, the aluminum alloy used in the present invention includes, for example, four elements containing any of the elements belonging to group Q, group Z, and group X in the Al-α alloy (preferably, Al-Ni alloy). For example, a ternary or quinary aluminum alloy may be used. Examples of the quaternary aluminum alloy include an Al-α-QZ alloy, an Al-α-QX alloy, and an Al-α-XZ alloy. An example of the quinary aluminum alloy is an Al-α-QXZ alloy.

As used herein, "substrate" is not limited as long as it is used in the TFT substrate, typically, it may be a glass substrate, a quartz substrate, plastic substrate, such as flexible substrate. The flexible substrate is a film-like substrate made of PET, PES, PEN, acrylic, and the like, and thus the weight of the semiconductor device is expected.

  The “substrate” may have an insulating layer such as silicon oxide, silicon nitride, silicon oxynitride on the surface, and such a substrate is also included in the scope of the present invention. The insulating layer may have a single layer structure, or may have a stacked structure in which two or more layers are stacked.

  Next, the manufacturing process of the TFT substrate according to the above embodiment will be described. Here, an example of a bottom gate type TFT substrate is shown, but the present invention is not limited to this, and the present invention is also applicable to a top gate type TFT substrate.

  In the method of manufacturing the wiring according to the present embodiment, a first thin film of nitrogen-containing aluminum alloy or nitrogen / oxygen-containing aluminum alloy is formed on a substrate by using a mixed gas of inert gas and nitrogen gas, or inert gas and nitrogen. The method includes a step of depositing by a reactive sputtering method using a mixed gas of gas and oxygen gas, and a step of depositing a second thin film of an aluminum alloy by a sputtering method.

  For example, when forming a nitrogen-containing aluminum alloy layer, the first thin film characterizing the present invention may be deposited by a reactive sputtering method using a mixed gas of an inert gas and nitrogen. In the case of forming an alloy layer, vapor deposition may be performed by a reactive sputtering method using a mixed gas of an inert gas and nitrogen gas / oxygen gas.

Specifically, the nitrogen-containing aluminum alloy layer is sputtered using a mixed gas of an inert gas such as Ar and Ne and N ₂ gas. The nitrogen-containing layer in the nitrogen-containing aluminum alloy can be controlled, for example, by changing the flow rate ratio between the inert gas and the N ₂ gas, and these flow rate ratios are generally inactive gas: N ₂ gas≈ If it adjusts in the range of 1: 0.07-0.16, the layer excellent in alkali resistance will be obtained.

The nitrogen / oxygen-containing aluminum alloy layer is sputtered using a mixed gas of an inert gas such as Ar and Ne and N ₂ gas / O ₂ gas. The nitrogen-containing layer in the nitrogen-oxygen-containing aluminum alloy can be controlled, for example, by changing the flow ratio of inert gas, N ₂ gas, and O ₂ gas, and these flow ratios are generally inert. By adjusting the gas: N ₂ gas: O ₂ gas≈1: 0.07 to 0.16: 0.01, a layer having excellent alkali resistance can be obtained.

Although other conditions are not specifically limited, For example, it is preferable to control as follows.
Substrate temperature: 60-180 ° C
Degree of vacuum: 1 × 10 ⁻⁵ Torr or less Gas pressure during film formation: 1 to 10 mTorr
DC power intensity during DC sputtering (per unit area of target)
: 1 to 10 W / cm ²

  The step of depositing the second thin film by a sputtering method is not particularly limited, and for example, the methods described in Patent Documents 1 to 3 described above can be referred to.

  Hereinafter, the manufacturing process of the TFT substrate according to the embodiment of the present invention will be described with reference to FIGS. In the following, an amorphous silicon TFT using hydrogenated amorphous silicon as a semiconductor layer is taken as an example, but the present invention is not limited to this. Here, an example in which an Al—Ni alloy is used as the aluminum alloy film is shown, but the present invention is not limited to this, and any of the aluminum alloys described above can be used.

A nitrogen-containing aluminum alloy film having a thickness of about 30 nm is formed on the glass substrate 1a by a reactive sputtering method using a mixed gas of an inert gas (typically Ar gas) and N ₂ gas. The flow ratio of the inert gas and N ₂ gas at this time is appropriately selected from the range of inert gas: N ₂ gas≈1: 0.07 to 0.16 depending on the target nitrogen content of the nitrogen-containing aluminum alloy film. That's fine.

  Next, an aluminum alloy film (without nitrogen) having a thickness of about 200 nm is formed on the nitrogen-containing aluminum alloy film by a sputtering method using only an inert gas (typically, Ar gas). Thereby, the 1st thin film of this embodiment which consists of laminated structures is obtained.

  The first thin film thus obtained is patterned (see FIG. 4), and the gate electrode 26 and the scanning line 25 are formed. At this time, in the step shown in FIG. 5 to be described later, it is preferable to etch the periphery of the Al—Ni alloy film in a taper shape of about 30 ° to 60 ° so that the coverage of the gate insulating film 27 is improved.

Next, as shown in FIG. 5, a gate insulating film 27 (silicon nitride film, SiN _x ) having a thickness of about 300 nm is formed at about 350 ° C. by using a method such as plasma CVD. Subsequently, for example, using a plasma CVD method, a non-doped hydrogenated amorphous silicon film (a-Si: H) having a thickness of about 200 nm and a silicon nitride film (SiN _{X having a} thickness of about 80 nm are formed on the gate insulating film 27. ) At 320 ° C.

Next, as shown in FIG. 6, the silicon nitride film is patterned by backside exposure using a gate wiring as a mask to form a channel protective film. Further, as shown in FIG. 7, an n ⁺ -type hydrogenated amorphous silicon film (n ⁺ a-Si: H) doped with phosphorus and having a thickness of 50 nm is formed at 320 ° C., and the hydrogenated amorphous silicon film and the n ⁺ The patterned hydrogenated amorphous silicon film.

Next, as shown in FIG. 8, an Al—Ni alloy film having a thickness of about 300 nm is formed and patterned to form source-drain wirings (28, 29). Further, the n ⁺ type hydrogenated amorphous silicon film on the channel protective film is removed using the source-drain wiring (28, 29) as a mask.

  Next, as shown in FIG. 9, for example, a silicon nitride film having a thickness of 300 nm is formed by a plasma CVD apparatus, and the protective film 30 is formed. The film formation temperature at this time was about 250 ° C. Next, the protective film 30 is patterned, and contact holes 32 are formed in the protective film 30 by dry etching. Etching is performed continuously even after the etching of the protective film 30 is completed, and 50% over-etching is performed in terms of time.

  Further, as shown in FIG. 10, ashing by oxygen plasma is performed. Thereafter, the photoresist 31 is stripped with, for example, an amine-based stripping solution to form an ITO film having a thickness of about 40 nm. Thereafter, by patterning, the transparent electrode 5 is formed as shown in FIG. 11, and at the same time, a TAB electrode is formed at the contact portion between the gate wiring and TAB at the end of the panel, thereby completing the TFT substrate (TFT array substrate).

  In the TFT array substrate formed based on these manufacturing processes, the transparent electrode (ITO film) 5 and the drain wiring 29 are in direct contact as shown in FIG.

  Using the TFT substrate thus obtained, the liquid crystal display device shown in FIG. 1 is completed according to a conventional method. A detailed method is described in, for example, Patent Documents 1 to 3 described above.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

  In the following Examples 1 to 2 and Comparative Example 1, simple TFTs shown in FIGS. 12 and 13 were produced and the TFT characteristics were evaluated. In the following examples, an Al-2 atomic% Ni alloy was used as the aluminum alloy layer.

Example 1
In this example, a gate wiring film 64 having a laminated structure composed of a nitrogen-containing Al-2 atomic% Ni alloy film 62a and an Al-2 atomic% Ni alloy film 63 was produced.

First, an aluminum nitride layer 62a having a thickness of 30 nm was deposited on the glass substrate 61 in the following manner. The content of nitrogen contained in the aluminum nitride is 25 atomic%.
Target material: Al-2 atomic% Ni sputtering target is used
(Size: diameter 100mm x thickness 5mm)
Sputtering equipment: Shimadzu “HSM-552” used Sputtering conditions (DC magnetron sputtering method)
Back pressure: 0.27 × 10 ⁻³ Pa or less Gas: Ar gas and N ₂ gas mixed
The flow rate ratio is Ar: N ₂ = 26.8: 3.2, and the total gas flow rate is 30 sccm.
Sputter power: DC200W
Distance between electrodes: 50mm
Substrate temperature: room temperature Glass substrate: # 1737 manufactured by Corning,
For evaluation of electrical resistivity and heat resistance, diameter 50 mm x thickness 0.7 mm,
For contact resistivity evaluation, diameter 10 mm x thickness 0.7 mm

  Next, all the gas in the sputtering apparatus was replaced with Ar gas, and an Al-2 atomic% Ni alloy film 63 having a thickness of 200 nm was deposited. The sputtering conditions were the same as those described above except that Ar gas was used.

  Next, a photoresist “AZ650F5” (manufactured by Clariant Japan) was applied by spin coating, and exposed to ultraviolet rays through a photomask having a test wiring pattern to form a gate wiring film 64.

Next, as a photoresist developer, an amine stripping solution (“TOK106” manufactured by Tokyo Ohka Kogyo Co., Ltd., containing 70% by mass of monoethanolamine and the balance: a stripping solution composed of an organic solvent) is immersed at 100 ° C. for 10 minutes. The photoresist film was removed. Then, the pinhole was generated by immersing in the washing tank which poured flowing water in the state where amine stripping liquid remained on the surface, and adjusting the dipping time and the flow rate of flowing water. As a result, pinholes having a density of about 10 ⁶ pieces / cm ² and a diameter of about 1 to 30 μm were formed on the gate wiring.

  Next, after performing photolithography, a Si nitride film (gate insulating film) 65 having a thickness of about 300 nm was formed by CVD.

Subsequently, an n-type semiconductor hydrogenated amorphous silicon film 66 [specifically, a non-doped hydrogenated amorphous silicon film (a) having a thickness of about 200 nm is formed on the Si nitride film (gate insulating film) 66 by CVD. -Si: H) and an n ⁺ -type hydrogenated amorphous silicon film (n ⁺ a-Si: H)] doped with 10 ¹⁹ phosphorus / P having a thickness of about 100 nm / cm ³ were stacked.

  Next, a molybdenum film 67 having a thickness of 300 nm was deposited by sputtering to produce a TFT (channel width 300 μm, channel length 20 μm) shown in FIG.

(Example 2)
In this embodiment, a gate wiring film 64 having a laminated structure composed of a nitrogen / oxygen-containing Al-2 atomic% Ni alloy film 62b and an Al-2 atomic% Ni alloy film 63 is used.

Specifically, in Example 1, the flow ratio of Ar gas, N ₂ gas, and O ₂ gas is Ar: N ₂ : O ₂ = 26.8: 3.2: 0.1, respectively. The TFT of Example 2 was fabricated in the same manner as in Example 1 except that an aluminum oxynitride layer having a thickness of 30 nm was vapor-deposited on a glass substrate (total gas flow rate: 30.1 sccm). The content of nitrogen contained in aluminum oxynitride is 25 atomic%, and the content of oxygen is 0.5 atomic%. The pinhole generated in the present embodiment is the same as that in the first embodiment.

  Next, unnecessary photoresist is removed with an alkaline developer “AZ MIF300” (manufactured by Clariant Japan), and a mixed acid solution of phosphoric acid, water and nitric acid (mixing ratio is phosphoric acid: water: nitric acid = 75: 20). : 5), the Al—Ni alloy in the lower part was etched.

(Comparative Example 1)
Here, a gate wiring film 64 (without formation of a nitrogen-containing Al-2 atomic% Ni alloy film or a nitrogen / oxygen-containing Al-2 atomic% Ni alloy film) composed only of the Al-2 atomic% Ni alloy film 63 was used. .

  Specifically, in Example 1, the TFT of Comparative Example 1 shown in FIG. 13 (channel width 300 μm, A channel length of 20 μm) was produced.

(Characteristic evaluation)
The characteristics of the TFTs of Example 1, Example 2 and Comparative Example 1 thus obtained were evaluated as follows.

  First, these TFTs were arranged in a dark room, and the current (dark current) when -5 V was applied to the gate wiring film 64 and a voltage of 5 V was applied between the Mo film 67a and the Mo film 67b was measured.

  Next, as shown in FIGS. 12 and 13, the backlight 70 was irradiated from the glass substrate 61 side, and the current (light irradiation current) flowing between the source electrode and the drain electrode was measured.

  Table 1 summarizes the results of dark current and light irradiation current when each TFT is used. For reference, Table 1 also shows the results of calculating the difference of (light irradiation current−dark current) in each TFT.

  In the TFT of Comparative Example 1, the light irradiation current was remarkably increased by the irradiation of the backlight light even though the TFT was in the off state, and increased by 4 digits compared to the dark current.

  On the other hand, in the TFT of Example 1 having an aluminum nitride layer between the substrate and the TFT of Example 2 having an aluminum oxynitride layer, the increase in the light irradiation current due to the backlight irradiation is a comparative example. Compared to 1, it was significantly suppressed. Specifically, the light irradiation currents in Example 1 and Example 2 only increased by about 2 times and 2.6 times compared to the dark current, respectively.

  From these results, it was found that the use of the lamination technique of the present invention can effectively suppress the deterioration of TFT characteristics even if pinholes are generated in the gate wiring film.

FIG. 1 is a schematic enlarged cross-sectional view illustrating a configuration of a typical liquid crystal panel to which an amorphous silicon TFT substrate is applied. FIG. 2 is a schematic enlarged view of region A in FIG. FIG. 3 is a diagram schematically showing the configuration of the wiring or electrode according to the embodiment of the present invention. FIG. 4 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 5 is an explanatory diagram showing an example of a manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 6 is an explanatory view showing an example of the manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 7 is an explanatory diagram showing an example of a manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 8 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 9 is an explanatory diagram showing an example of a manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 10 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 11 is an explanatory view showing an example of a manufacturing process of the TFT substrate shown in FIG. 2 in order. FIG. 12 is a diagram schematically illustrating the configuration of the TFT of the first embodiment. FIG. 13 is a diagram schematically showing the configuration of the TFT of Comparative Example 1.

Explanation of symbols

1 TFT substrate (TFT array substrate)
1a Glass substrate 2 Counter substrate (counter electrode)
3 Liquid crystal layer 4 Thin film transistor (TFT)
5 Transparent pixel electrode (transparent electrode, pixel electrode, ITO film)
6 Wiring part 7 Common electrode 8 Color filter 9 Light shielding film 10 Polarizing plate 10a, 10b Deflection plate 11 Alignment film 12 TAB tape 13 Driver circuit 14 Control circuit 15 Spacer 16 Sealing material 17 Protective film 18 Diffusion plate 19 Prism sheet 20 Light guide plate 21 Reflector 22 Backlight 23 Holding frame 24 Printed circuit board 25 Scan line 26 Gate wiring (gate electrode)
27 Gate insulating film (silicon nitride film)
28 Source wiring (source electrode)
29 Drain wiring (drain electrode)
30 Protective film (silicon nitride film)
31 Photoresist 32 Contact hole 33 Amorphous silicon channel film (active semiconductor film)
34 Signal line (source-drain wiring)
51 Substrate 52 First thin film (nitrogen-containing aluminum alloy or nitrogen / oxygen-containing aluminum alloy)
53 Second thin film (aluminum alloy)
61 glass substrate 62a nitrogen-containing Al-2 atomic% Ni alloy film 62b nitrogen / oxygen-containing Al-2 atomic% Ni alloy film 63 Al-2 atomic% Ni alloy film 64 gate wiring film 65 Si nitride film (gate insulating film)
66 n-type semiconductor hydrogenated amorphous silicon film 67, 67a, 67b Molybdenum film 70 Backlight 100 Liquid crystal panel

Claims (7)

In a transistor substrate in which a wiring or an electrode is provided on a transparent substrate and a channel layer of a thin film transistor is formed on the wiring or electrode via a gate insulating film ,
The wiring or the electrode has a laminated structure composed of a first thin film of nitrogen-containing aluminum alloy and a second thin film of aluminum alloy in order from the substrate side,
The transistor substrate, wherein the ratio of nitrogen contained in the first thin film is 13 atomic% or more and 50 atomic% or less. In a transistor substrate in which a wiring or an electrode is provided on a transparent substrate and a channel layer of a thin film transistor is formed on the wiring or electrode via a gate insulating film ,
The wiring or the electrode has a laminated structure composed of a first thin film of nitrogen / oxygen-containing aluminum alloy and a second thin film of aluminum alloy in this order from the substrate side,
It said first proportion of nitrogen contained in the thin film is 50 atomic% or less 13 atomic% or more, the transistor substrate, wherein the ratio of oxygen is not more than 10 atomic%. 3. The transistor substrate according to claim 1, wherein a thickness of the first thin film is in a range of 10 nm to 100 nm. The aluminum alloys constituting the first thin film and the second thin film are the same or different, and at least one element selected from the group consisting of Ni, Ag, Zn, Cu, and Ge is used as the alloy component. The transistor substrate according to any one of claims 1 to 3, wherein the transistor substrate is contained in a range of 1 atomic% to 6 atomic%. Transistor substrate according to the wiring or the electrode is any one of claims 1 to 4, a gate wiring or a gate electrode. A method of making a wiring or an electrode used in the transistor substrate according to any one of claims 1 to 5
Using a first thin film of nitrogen-containing aluminum alloy or nitrogen / oxygen-containing aluminum alloy on a transparent substrate, a mixed gas of inert gas and nitrogen gas, or a mixed gas of inert gas and nitrogen gas / oxygen gas is used. Vapor deposition by the reactive sputtering method,
Depositing a second thin film of aluminum alloy by sputtering;
A method for manufacturing a wiring or an electrode comprising: Display device comprising a transistor substrate according to claim 1.