JP2012189725A - WIRING FILM AND ELECTRODE USING Ti ALLOY BARRIER METAL AND Ti ALLOY SPUTTERING TARGET - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel wiring film having a characteristic of excellent wet etching processability.SOLUTION: A wiring film to be used in a display device or a touch panel sensor, comprises a layered structure of two or more layers including a Ti alloy layer containing 3 to 50 atm.% of an element of a group X (where, the group X is composed of at least one element selected from the group consisting of a rare earth element, Ge, Si, Sn, Hf, Zr, Mg, Ca, Sr, Al, Zn, Mn, Co, Fe and Ni) and/or 0.2 to 3.0 mass% of oxygen as an alloy component, and a balance of Ti and inevitable impurities; and a layer of pure Cu or a Cu alloy.

Description

  The present invention relates to a thin film for wiring used in a display device or a touch panel sensor excellent in wet etching property. In detail, it is provided with a wiring film useful for forming various wirings and electrodes used for display devices such as liquid crystal displays and organic EL displays and touch panel sensors, and wirings and / or electrodes formed with the wiring films. The present invention relates to a sputtering target useful for forming a Ti alloy layer constituting a display device, a touch panel sensor, and a wiring film. Hereinafter, the background art of a display device targeted by the present invention will be described using a liquid crystal display as a representative example, but the present invention is not intended to be limited thereto.

  In an active matrix liquid crystal display device such as a liquid crystal display, a thin film transistor (hereinafter referred to as “TFT”) is used as a switching element. The liquid crystal display device is composed of a TFT array substrate having TFT elements, a counter substrate disposed opposite to the TFT array substrate and having a common electrode, and a liquid crystal layer filled between the TFT substrate and the counter substrate. Has been.

  A TFT element constituting a TFT substrate is connected to a gate electrode for controlling on / off of the TFT formed on the glass substrate, a semiconductor silicon layer (silicon semiconductor layer) provided via a gate insulating film, and the like. It has a drain electrode and a source electrode. A transparent conductive film (transparent pixel electrode) used for the pixel electrode of the liquid crystal display unit is further connected to the drain electrode. The wiring metal used for the gate electrode, the drain electrode, and the source electrode is required to use pure Cu or a Cu alloy for reasons such as low electrical resistance (specific resistance).

  The Mo-based film (hereinafter, meaning to include pure Cu and Cu alloy) and the interface between the insulator layer, the semiconductor layer, and the glass, and the interface between the TFT and the semiconductor silicon layer of the TFT are not directly contacted by Mo. A barrier metal layer made of a refractory metal such as Cr, W or the like is provided.

  If the Cu-based film is brought into direct contact with the TFT semiconductor layer without the barrier metal layer interposed, subsequent processes (for example, a film forming process such as an insulating layer formed on the TFT, heat treatment such as sintering and annealing, etc.) Due to the thermal history in the process or the like, the TFT characteristics deteriorate when Cu atoms diffuse into the silicon semiconductor layer, and the electrical resistance of the Cu-based film increases when Si atoms diffuse into the Cu-based film. Further, when a diffused Cu and Si layer is formed (diffusion layer), film peeling may occur from the diffusion layer. Moreover, there is a problem that the Cu-based film has insufficient adhesion to a glass substrate or an insulator layer.

  Although the barrier metal layer is effective as a means for solving these problems, when a barrier metal layer of a refractory metal such as Mo, Cr, Ti, W is formed, a Cu-based film and a barrier metal are formed during the microfabrication process. It was necessary to perform different etching processes for the layers (two-stage etching). When etching is performed in a plurality of processes, not only the etching cost increases, but also the process becomes complicated and the throughput is lowered. Also, if the Cu-based film and the barrier metal layer are collectively etched, the barrier metal and the Cu-based film have different etching rates with respect to the chemical solution, so that the barrier metal layer tends to remain in the wrinkles and step shapes, resulting in a decrease in processing accuracy. There was a problem. These wrinkles and steps cause poor coverage of the film laminated on the upper layer, causing current leakage and short-circuiting between wirings, and reducing yield.

  It is proposed to use an etching solution suitable for both the barrier metal layer and the Cu-based film as a technique for collectively processing the Cu-based film and the barrier metal layer while avoiding the problem of workability due to wet etching. ing.

  For example, in wet etching, a mixed acid etching solution containing sulfuric acid and nitric acid is usually used, but Mo, Cr, Ti, W, etc. constituting the barrier metal layer have an etching rate much higher than Cu constituting the wiring film. Therefore, the barrier metal layer tends to remain in a step shape or a ridge shape, and a good wiring shape cannot be obtained. In particular, wiring processing of a display device such as a liquid crystal display device requires high-precision wiring processing. If etching of the barrier metal layer takes time, the etching of the Cu-based film proceeds so much that the Cu-based film disappears. It is difficult to process with desired accuracy.

Therefore, for example, wet etching is performed using OXONE (registered trademark, 2KHSO ₅ · KHSO ₄ · K ₂ SO ₄ ) or a mixture of OXONE, hydrofluoric acid (HF), and ammonium fluoride (NH ₄ F) as an etchant. A technique for improving etching failure when performed (Patent Document 1) has been proposed. Specifically, in Patent Document 1, when an OXONE-containing etching solution is used by using a Mo alloy containing W, Nd, and Nb as a barrier metal and using a Cu / Mo alloy laminated film for gate wiring and data wiring. A method for preventing the Mo alloy film from being damaged and preventing the Cu-based film from peeling off is disclosed. However, it has been found that when the above etching solution is used for the laminated film of the Cu-based film and the pure Ti film, the pure Ti film that is a barrier metal remains in a step or bowl shape.

JP 2004-163901 A

  The present invention has been made paying attention to the above circumstances, and an object thereof is to improve the workability of a Cu-based film and a Ti-based alloy film by wet etching. Specifically, it is an object to provide a wiring film having good processability that can form a more excellent tapered shape without steps, wrinkles, residues, etc. of a Ti-based alloy film after wet etching. In particular, a wiring film formed of a laminated structure of a Ti-based alloy film having a higher etching rate than a conventional barrier metal layer and a Cu-based film, and a wiring and / or an electrode formed of the wiring film are provided. The object is to provide a sputtering target suitable for forming a display device, a touch panel sensor, and a Ti alloy film.

  The present invention that has solved the above-mentioned problems is an X-group element (X is a rare earth element, Ge, Si, Sn, Hf, Zr, Mg, Ca, Sr, Al, Zn, Mn, Co, Fe, And at least one element selected from the group consisting of Ni) and a Ti alloy layer containing 3 to 50 atomic% and / or 0.2 to 3.0 mass% of oxygen, the balance Ti and inevitable impurities, A wiring film for a display device or a touch panel sensor having a gist of having a laminated structure of two or more layers including a layer made of pure Cu or a Cu alloy.

  In the present invention, it is also a preferred embodiment that the Ti alloy layer is formed above and / or below the layer made of pure Cu or Cu alloy.

  Furthermore, in the present invention, it is also a preferred embodiment that the thickness of the Ti alloy layer is 10 to 100 nm.

  Furthermore, a display device and a touch panel sensor provided with wirings and / or electrodes formed of the wiring film are also included in the present invention.

  Furthermore, the present invention provides a sputtering target used for forming a Ti alloy layer, which contains 3 to 50 atomic% of the X group element and / or 0.2 to 3.0 mass% of oxygen, with the balance being Ti and inevitable. A Ti—X alloy sputtering target characterized by being an impurity is also included.

  According to the present invention, instead of a conventional barrier metal layer made of a refractory metal, a Ti—X alloy film containing a predetermined element X having a high etching rate, a Ti—X—O alloy film containing a predetermined amount of oxygen, or By using a Ti—O alloy film (hereinafter, these may be collectively referred to as a Ti-based alloy film), a laminated structure with a Cu-based film (meaning including pure Cu and Cu alloy; hereinafter the same). A wiring film having good etching property can be provided. Therefore, if the wiring film defined in the present invention is used, it becomes possible to form a good cross-sectional shape by suppressing the steps and defects remaining in the batch wet etching process, and the Cu-based film and the Ti-based film can be formed. The wiring process of the alloy film can be facilitated and the production yield can be improved. Moreover, according to this invention, the sputtering target suitable for film-forming of the Ti type alloy film which comprises the said film | membrane for wiring can be provided.

FIG. 1 is a photograph showing a step width (photo from the second layer side of the laminated film) of the laminated wiring film of the pure Ti film (first layer: lower side) and the pure Cu film (second layer: upper side). Yes (optical microscope, magnification 500 times). FIG. 2 shows a step width of a laminated wiring film of a Ti-30 atomic% Al alloy film (first layer: lower side) and a pure Cu film (second layer: upper side) (photo from the second layer side of the laminated film). (Optical microscope, magnification 500 times). FIG. 3A is a graph showing the relationship between the etching rate of the Ti—X alloy and the step length when the etching solution A is used. FIG. 3B is a graph showing the relationship between the etching rate of the Ti—X alloy and the step length when the etching solution B is used.

  The inventors of the present invention have made extensive studies in order to provide a novel wiring film having excellent workability by wet etching. In particular, in order to provide a wiring film having excellent wet etching properties when batch wet etching is performed, studies have been made focusing on a Ti-based material used as a base material (barrier metal) of a Cu-based film. As a result, instead of pure Ti, a Ti—X alloy containing a predetermined element X, a Ti—O alloy containing a predetermined amount of oxygen, and a Ti—X—O alloy containing a predetermined element X and a predetermined amount of oxygen are used as a barrier metal. As a result, it was found that the intended purpose was achieved, and the present invention was completed.

  Thus, the present invention is a barrier metal composed of a Cu-based film (layer made of pure Cu or Cu alloy) having a lower resistance than Al and a Ti-based alloy film (Ti alloy layer) as a wiring material for display devices and touch panel sensors. A feature is that workability by wet etching is improved by using a wiring film having a laminated structure composed of In particular, when a fluoride-containing etchant is used as an etchant for etching a wiring film having a laminated structure including a Ti-based alloy film and a Cu-based film of the present invention, batch patterning can be easily performed, and a Ti-based alloy film step Occurrence of wrinkles and wrinkles can be suppressed, and a good wiring shape can be obtained.

(First layer)
First, the Ti—X alloy film (first layer) of the present invention will be described.

  The group X element used in the present invention is [rare earth element, Ge, Si, Sn, Hf, Zr, Mg, Ca, Sr, Al, Zn, Mn, Co, Fe, and Ni]. These elements may be added alone or in combination of two or more.

  “Rare earth element” means a group of elements obtained by adding Sc (scandium) and Y (yttrium) to a lanthanoid element (a total of 15 elements from La with atomic number 57 to Lu with atomic number 71 in the periodic table). To do. One or more rare earth elements can be used.

  A preferred X group element is at least one selected from the group consisting of Ge, Si, Sn, Hf, Zr, Mg, Ca, Sr, Al, Zn, Mn, Co, Fe, and Ni, more preferably Sn, Hf , Zr, and Al, at least one selected from the group consisting of Al, and more preferably Al and / or Zr.

  As shown in the examples described later, it has become clear from the experimental results of the present inventors that these elements have the effect of accelerating the wet etching rate when a fluoride-containing etching solution is used. That is, the Ti alloy film containing a predetermined amount of the X group element suppresses the formation of a dense Ti oxide film (passive film) as seen in a pure Ti film or a Ti alloy film containing an element other than the X group element. be able to. Moreover, since the X group element (and its oxide) is likely to be eluted due to the fluoride in the fluoride-containing etching solution, the etching rate of the Ti—X alloy film is significantly increased. Accordingly, since the difference in etching rate with the Cu-based film is reduced as compared with the case where a pure Ti film is used, the upper Cu-based film and the underlying Ti-X alloy are processed when the wiring film is processed by batch wet etching. Steps at the interface with the film and process traces of the ridge shape can be reduced, and a good etching shape can be obtained.

  Thus, if the Ti-X alloy film of the present invention is used, excellent wet etching properties can be obtained.

  In the present invention, the content of the group X element (a single amount when included alone or a total amount when two or more types are included) is 3 atomic percent or more and 50 atomic percent or less. In order to effectively exhibit the wiring processability by the good wet etching by adding the X group element, the content of the X group element needs to be 3 atomic% or more. On the other hand, the etching rate increases as the content of the group X element increases, but the cost increases due to the use of expensive rare earth elements. Therefore, the upper limit of the content of the X group element is set to 50 atomic%. The preferable content of the group X element is 4 atom% or more and 40 atom% or less, more preferably 5 atom% or more and 30 atom% or less.

  The Ti-X alloy film of the present invention contains the X group element, and is the balance Ti and inevitable impurities. Examples of unavoidable impurities include Fe, Si, N, C, and H. However, these unavoidable impurities are not limited to these unavoidable impurities, and they are not limited unless the characteristics of the present invention are impaired. Minor amounts of can be tolerated. In addition, although Fe, Si, etc. prescribed | regulated as an X group element by this invention may be mixed as an unavoidable impurity, even in that case, when it is about 1.0 mass% or less independently, an unavoidable impurity and In other words, it is not included in the group X element (hereinafter the same).

  Further, for the purpose of effectively exhibiting the excellent action of other elements, a Ti—X—O alloy film containing 0.2 to 3.0% by mass of oxygen (solid solution oxygen) described later may be used.

  The Ti—X alloy film of the present invention has been described above. Next, the Ti—O alloy film of the present invention will be described.

  The Ti—O alloy film which is another configuration of the present invention having an excellent wet etching rate contains 0.2 to 3.0% by mass of oxygen as an alloy component, and the balance is Ti and inevitable impurities.

  The presence of a predetermined amount of dissolved oxygen in the Ti film has an effect of improving the etching rate. That is, when a Ti—O alloy film containing a predetermined amount of dissolved oxygen is wet-etched with a fluoride-containing etchant, the time from the start of dissolution of the Ti—O alloy film to the start of etching becomes faster after immersion in the etchant. Therefore, since the elution of the Ti alloy proceeds during the wet etching process, it is possible to suppress the generation of steps and wrinkles in the Ti-based alloy film. In order to exert such an effect, the oxygen content (solid solution amount) in the Ti—O alloy film is 0.2 mass% or more, preferably 0.3 mass% or more, more preferably 0.35 mass% or more. Is desirable. On the other hand, if the oxygen content is excessively increased, the etching rate is drastically decreased, and the effect of shortening the etching time cannot be obtained. Therefore, the oxygen content is 3.0 mass% or less, preferably 1.5 mass% or less, More preferably, it is 1.2 mass% or less, More preferably, it is 1.0 mass% or less. The amount of dissolved oxygen in the Ti-based alloy film of the present invention can be measured by SIMS (Secondary Ion Mass Spectrometry).

  When oxygen is contained in the Ti-based alloy film of the present invention, oxygen must be present in a solid solution state. This is because when oxygen is present as titanium oxide, the titanium oxide is passive and causes a decrease in the etching rate. It should be noted that the presence or absence of titanium oxide can be confirmed by visual observation of the transparency of the corresponding part of the film, in addition to various analyzers.

  In addition, when oxygen is contained in the Ti-based alloy film in a solid solution state, in addition to the target containing a predetermined amount of oxygen in advance as described above, oxygen is contained in the atmosphere during film formation as described later. This can also be achieved by introducing.

  The Ti—O alloy film according to the present invention contains 0.2 to 3.0 mass% of oxygen (solid solution state) as an alloy component, and the balance is Ti and inevitable impurities. Examples of unavoidable impurities include Fe, Si, N, C, and H. However, these unavoidable impurities are not limited to these unavoidable impurities, and they are not limited unless the characteristics of the present invention are impaired. Minor amounts of can be tolerated.

  For example, when Fe or Si is contained as an unavoidable impurity, the content thereof is preferably as small as possible, and the concentration of Fe and Si is preferably about 1.0% by mass or less.

  As the first layer of the present invention, both a Ti—X alloy film and a Ti—O alloy film are desirable embodiments. However, in order to further enhance the effect, the predetermined amount of oxygen (solid solution state) is added to Ti—X. A Ti—X—O alloy film may be included in the alloy film.

  The Ti—X—O alloy film can exhibit the effects of the Ti—X alloy film and the Ti—O alloy film. That is, it is thought that the workability by wet etching is further improved in order to exhibit the effect of suppressing the formation of passivation and the effect of elution of Ti alloy.

  The upper limit of the film thickness of the Ti-based alloy film as the first layer may be appropriately determined in consideration of the electrical resistivity of the wiring film itself. However, when the film thickness is increased, steps and residues are easily generated and the etching time is increased. Becomes longer, and the second layer (pure Cu or Cu alloy film) is excessively etched. Therefore, the thickness is preferably 100 nm or less, and more preferably 50 nm or less. The lower limit of the film thickness of the first layer is not particularly limited, but if the film thickness is too thin, the Ti-based alloy film disappears in the substrate surface due to the influence of the in-plane film thickness distribution or process (for example, etching other layers) In this case, it is conceivable that a portion where Ti is scraped and disappears) is generated.

(Second layer)
Next, the second layer constituting the wiring film of the present invention will be described. The second layer of the present invention is composed of pure Cu (remainder unavoidable impurities) or a Cu alloy composed of an alloy element (preferably the above alloy element), the remainder Cu and unavoidable impurities. This second layer is formed for the purpose of reducing the electrical resistivity of the entire wiring film, and therefore, it is desirable to make the electrical resistivity lower than that of the first layer. The specific wiring resistance is not particularly limited, and the resistance value of the wiring may be appropriately controlled by adjusting the film thickness and composition of the second layer as necessary.

  The alloy element added to the second layer of the present invention is not particularly limited, including pure Cu, and can be used by appropriately controlling the composition and content of the alloy element. Specifically, Cu-0.5 atomic% Ni, Cu-0.5 atomic% Zn, Cu-0.3 atomic% Mn, etc. are preferably used as such a Cu alloy. The alloy element applicable to the second layer may contain a gas component of oxygen gas or nitrogen gas, and for example, Cu-O or Cu-N can be used. An alloy element may be used independently and may use 2 or more types together.

  The preferred film thickness of the second layer of the present invention is not particularly limited, and it varies depending on the application site of the wiring film and the use, but if the film thickness is too thin, the effect of reducing the electrical resistivity of the entire film is sufficient. Since it cannot be obtained, the thickness is preferably 100 nm or more, more preferably 150 nm or more. On the other hand, if the second layer is too thick, the coverage of the laminated film (for example, the film formed on the upper layer) is deteriorated, and there is a problem that the process takes a long time because the sputtering time becomes long. It is desirable that the thickness is 1000 nm or less, more preferably 800 nm or less, and still more preferably 600 nm or less.

  The film thickness of the entire wiring film including the first layer and the second layer is not particularly limited, and may be appropriately adjusted according to the film thickness required within a preferable range of each layer.

  In the wiring film of the present invention, for example, when viewed from the substrate side, the second layer may be directly laminated on the first layer, and conversely, the first layer is laminated directly on the second layer. May be. Further, the wiring film of the present invention may be composed of only the first layer and the second layer, or an arbitrary third layer may be formed. In the case of three layers, the first layer and the third layer made of a Ti alloy are preferably stacked on the upper and lower portions of the second layer, and the third layer is preferably stacked on the second layer.

(3rd layer)
Next, the third layer used in the present invention will be described. The composition of the third layer of the present invention is not particularly limited. For example, the composition may be the same as or similar to the first layer (differing in the type and addition amount of the X group element), or may be different from the second layer. Cu alloys and compositions different from these may be selected as appropriate according to required film characteristics.

  For example, it is possible to form a third layer such as a Cu alloy film or a Ti-based alloy film as a barrier layer for suppressing oxidation of the wiring from the thermal history of the manufacturing process, etc., or to improve electrical resistivity. A third layer may be provided according to various purposes, such as forming a third layer having an excellent composition, and the composition of the third layer is also appropriately within a range that does not impair the effects of the first layer and the second layer. It is also possible to set.

  The film thickness of the third layer may be set as appropriate according to the part to which the wiring film is applied, the application, and the like.

  For example, the third layer may be provided on the side directly connected to the insulating film of the thin film transistor. At that time, it is also preferable to use a Ti—X alloy containing the X group element as the composition of the third layer. Of course, the first layer and the third layer do not need to have exactly the same composition, and the compositions may be different as long as the above-described requirements for the Ti-X alloy are satisfied. In order to improve productivity, it is preferable that the first layer and the third layer have the same composition, but the first layer and the third layer may have different compositions. The film thickness may be the same as or different from that of the first layer.

  The wiring film of the present invention has been described above. Next, a method for forming a wiring film according to the present invention will be described.

  The first layer and the second layer constituting the wiring film of the present invention can be formed by using a vapor deposition method, a spray method, an ALD method, or the like, but is preferably formed by a sputtering method. If the sputtering method is used, a wiring film having almost the same composition as that of the sputtering target can be formed, and a thin film with excellent in-plane uniformity of film thickness and components can be easily formed.

  The first to third layers are preferably formed by sputtering. Specifically, a film may be formed by a sputtering method using the material constituting the first to third layers (sputtering target).

  In the case of a laminated structure in which a second layer is formed on the first layer, after forming the first layer, a sputtering method using a sputtering target having a composition constituting the second layer is formed thereon. The second layer may be formed by Thus, after forming the wiring film having a laminated structure, predetermined patterning may be performed. From the viewpoint of coverage, the cross-sectional shape is preferably processed into a taper shape with a taper angle of about 45 to 60 °.

  As a sputtering target used for forming the Ti-X alloy film (first layer) of the present invention, an X group element (X is a rare earth element, Ge, Si, Sn, Hf, Zr, Mg, Ca, Sr, Al, A Ti—X alloy sputtering target containing 3 to 50 atomic% of at least one element selected from the group consisting of Zn, Mn, Co, Fe, and Ni) and the balance Ti and inevitable impurities may be used.

  Furthermore, when the Ti—X—O alloy target containing the predetermined amount (0.2 to 3.0% by mass) of oxygen in the target is used, the Ti—X—O alloy film can be formed. .

  As a sputtering target used for forming the Ti—O alloy film of the present invention, a Ti—O alloy sputtering target containing the above-mentioned predetermined amount (0.2 to 3.0% by mass) of oxygen and the balance Ti and inevitable impurities is used. Use it.

In addition, when oxygen is contained in the Ti-based alloy wiring film in a solid solution state, oxygen is introduced into the atmosphere during film formation in addition to the target containing a predetermined amount of oxygen as described above. May be. For example, an oxidizing gas such as oxygen (O ₂ ) gas or O ₃ containing oxygen atoms can be used. As a method for supplying oxygen, a mixed gas obtained by adding oxygen to a process gas (for example, Ar) that is usually used in a sputtering method may be used. Since the amount of dissolved oxygen in the Ti-based alloy wiring film can be controlled by the mixing ratio of the oxygen gas in the process gas, the mixing ratio may be adjusted as appropriate according to the amount of oxygen to be introduced.

  As a sputtering target used for forming the Cu-based film, a Cu alloy sputtering target containing a desired composition and comprising the remaining Cu and inevitable impurities may be used.

  The composition of the sputtering target in the case of using a plurality of alloy elements may be adjusted by using targets having different compositions, or may be adjusted by chip-on the alloy element metal on the sputtering target.

  In addition, what is necessary is just to form into a film using the sputtering target of a desired component composition also when laminating | stacking a 3rd layer.

  The shape of the target includes those processed into an arbitrary shape (a square plate shape, a circular plate shape, a donut plate shape, a cylindrical shape, etc.) according to the shape and structure of the sputtering apparatus.

  Examples of the method for producing the sputtering target for the Ti-based alloy film of the present invention include a method obtained by producing an ingot made of a Ti alloy having a desired component composition by a melt casting method or a powder sintering method. .

  Examples of the display device including the wiring and / or electrode formed of the wiring film of the present invention include various display devices such as a liquid crystal display, an organic EL display, and a plasma display.

  In addition, examples of the touch panel sensor provided with the wiring and / or electrode formed of the wiring film of the present invention include various types of touch panel sensors such as a capacitance method, an electromagnetic induction method, a resistance film method, and an optical sensor method. .

  The wiring film of the present invention is suitably used for various wirings and electrodes of a wiring structure such as ULSI, ASIC, diode, thin film transistor, and thin film transistor substrate incorporated in a display device such as a liquid crystal display or a touch panel sensor. Specifically, it can be used to form various wirings such as scanning lines, source lines, and drain lines, and various electrodes such as gate electrodes and source-drain electrodes. In manufacturing a display device or a touch panel sensor having the above wiring structure, a general process of the display device can be employed.

  For example, when the wiring film of the present invention is applied to the wiring structure of a display device, the following configuration can be adopted. Directly on the substrate, an insulating film; a semiconductor layer of the thin film transistor; a wiring / electrode; a transparent conductive film; and at least one selected from the group consisting of the substrate, the insulating film, the semiconductor layer of the thin film transistor, and the transparent conductive film A wiring structure having a wiring film to be connected is exemplified. The wiring film of the present invention can be used for the wirings and electrodes. The wiring film of the present invention can also be used for part or all of the wiring (and / or electrode) of the display device. When applied to a plurality of wirings / electrodes, the wiring film may have the same or different component composition. it can.

  In manufacturing a wiring structure having wirings and / or electrodes formed from the wiring film of the present invention, a general process of a display device can be adopted. Other parts other than the wiring film of the present invention are not particularly limited, and those usually used in the field of display devices can be employed.

  For example, the substrate used for the display device or the touch panel sensor is not particularly limited as long as it is normally used. Typically, a transparent substrate typified by a glass substrate (non-alkali glass, high strain point glass, soda lime glass, etc.), a flexible substrate such as a PET film or a metal foil, and the like can be given.

  For example, as a transparent conductive film constituting a pixel electrode used for a display device or a touch panel sensor, amorphous ITO, ITO, IZO, ZnO, or the like is typically exemplified.

  In addition, a semiconductor layer of a thin film transistor used for a display device or a touch panel sensor is not particularly limited, and hydrogenated amorphous silicon, amorphous silicon, microcrystalline silicon, polycrystalline silicon, single crystal silicon, and an oxide semiconductor (eg, InGaZnO, ZnO, ZnSnO) AlZnO, GaZnO, InZnSnO, ITO) and the like.

In addition, an insulating film such as a gate insulating film or a protective film formed on the semiconductor is not particularly limited, and examples thereof include commonly used ones such as SiO ₂ , SiON, and SiN.

The Ti-based alloy film of the present invention is desirably etched using a fluoride-containing wet etchant. The type of the fluoride-containing wet etching solution is not particularly limited, but the wet etching solution for etching the Ti-based alloy film of the present invention includes hydrofluoric acid (HF), ammonium fluoride (NH ₄ F), and the like. This is because a significant improvement in the etching rate is observed when the fluoride-containing etching solution is used. Specifically, an etchant containing fluoride and an oxidizing agent (or further acid) (for example, JP 2008-53374 A, JP 2007-67367 A, JP 2010-199121 A); fluoride and iodic acid Etching solution containing sulfuric acid (for example, JP-A-2000-133635); Etching solution containing peroxodisulfuric acid, potassium hydrogen and hydrofluoric acid (for example, JP-A-2001-59191); hydrogen peroxide and fluoride, sulfuric acid (or Etching solution containing nitric acid or phosphoric acid (for example, JP 2004-43850 A); Etching solution containing nitric acid, hydrofluoric acid, and acetate ion supply source (for example, JP 2004-71920 A); Fluorine ion supply source And an etchant containing hydrogen peroxide, sulfate, phosphate, and azole compound (for example, Japanese Patent Application Laid-Open No. 2008-2008). 288575); an etching solution containing fluorine compound and iron ions, nitric acid, hydrochloric acid, perchloric acid, methanesulfonic acid, and phosphorous acid or phosphoric acid (for example, JP 2010-199121 A); hydrofluoric acid and fluorine Etching solution containing ammonium fluoride and glycerin (for example, JP-A-11-87325); Etching solution containing ammonium hydrogen fluoride and hydrogen peroxide (for example, JP-A-2008-81832); hydrofluoric acid and water, Examples thereof include an etching solution containing hydrosilicic acid salt (for example, JP 2009-182218 A).

  Moreover, additives, such as a supplementary oxidizing agent added normally, may be contained in etching liquid, and a commercial item can be used for fluorine compound containing etching liquid.

  As described above, the wiring film having a laminated structure including the Ti-based alloy film (first layer) and the Cu-based film (second layer) according to the present invention has the second layer because the etching rate of the first layer is high. And the etching rate difference is small. Therefore, when the wiring film including the first layer and the second layer is collectively etched with the fluoride-containing etching solution, a good wiring shape can be obtained without remaining in a step shape or a ridge shape.

  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 can be implemented with modifications within a range that can meet the above and the following purposes. These are all included in the technical scope of the present invention.

  In this example, a sample produced by the following method was used to measure the step length after etching of the wiring film (laminated structure of the first layer / second layer). A sample in which only the first layer was formed was prepared, and the etching rate was measured. In the examples, Ti-X alloy films having various alloy compositions shown in Tables 1 and 2 are formed by sputtering on a pure Ti target with X alloys having various compositions and adding a group X element added thereto. Used as a target. Note that when a Ti—O alloy film was produced, an oxygen-containing Ti alloy target was used.

Example 1
(Evaluation of step length after etching)
(Sample preparation)
A first layer (Ti-X alloy film: film thickness 50 nm) and a second layer (pure Cu film) having the composition shown in Table 1 on a glass substrate (manufactured by Corning: Eagle XG, φ4 inch, thickness = 0.7 mm) : A film thickness of 300 nm) was sequentially formed by a sputtering method to prepare a sample of a laminated film.

For sputtering, “HSM-552” manufactured by Shimadzu Corporation is used, and DC magnetron sputtering method [back pressure: 0.27 × 10 ⁻³ Pa or less, atmospheric gas: Ar, Ar gas pressure: 2 mTorr, Ar gas flow rate: 30 sccm, sputtering power: DC 260 W, distance between electrodes: 50.4 mm, substrate temperature: 25 ° C. (room temperature)] to prepare a sample in which the first layer and the second layer were formed.

  The composition of the first layer and the second layer was confirmed by quantitative analysis using an ICP emission spectrometer (ICP emission spectrometer “ICP-8000 type” manufactured by Shimadzu Corporation). The film thickness was measured with an α-step manufactured by KLA-TENCOR. For comparison, a sample (No. 1: pure Ti / pure Cu laminated structure) in which a pure Ti film was formed in the same manner as the above sample was prepared.

  Next, after each sample was processed into a line and space pattern (50 μm interval) using TSMR8900 (manufactured by Tokyo Ohka Co., Ltd.) as a photoresist, a test piece was prepared by cutting each sample into a size of 1 cm × 4 cm. Each test piece was immersed in an etching solution and etched. Etching process conditions are as follows.

  As the etching solution, either etching solution A (described in Table 1) or etching solution B (described in Table 2) was used.

Etching solution A: As a chemical solution similar to the etching solution described in Table 1 (Japanese Patent Laid-Open No. 2004-43850), hydrogen peroxide solution: nitric acid: phosphoric acid: ammonium fluoride = 18: 2: 4: 1 A Ti single layer film of about 300 nm was used whose concentration was adjusted (diluted) so that it could be dissolved in about 5 minutes.)
Etching solution B: Table 2 (KSMF-240 manufactured by Kanto Chemical Co., Inc.)
Treatment temperature: room temperature for etchant A, 40 ° C for etchant B
Treatment method: standing (immersion)
Processing time: Etching was performed up to a time corresponding to 150% (from just etching to 50% overetching) when the time when the etching removal of the wiring film by the resist was confirmed as 100%.

  Next, the resist is removed, and the specimen is observed from above the test piece (second layer side) with an optical microscope (magnification 500 times), and the difference in width between the pure Cu film after etching and the Ti-based alloy film (step length: pure) The length from the end of the Cu film to the end of the Ti-based alloy film was measured. The smaller the step length, the better the etched shape.

  Evaluation criteria: A step length of 90% or less of a pure Ti film was evaluated as good (◯). In this example, when the etching solution A is used (Table 1), the step length is 4.3 μm or less, and when the etching solution B is used (Table 2), the step length is 1.6 μm or less. evaluated.

  These results are shown in Tables 1 and 2.

  From Table 1 and Table 2, it was found that the step length due to etching tended to decrease as the addition amount of the X group element in the Ti-X alloy film increased, and a good etching shape was obtained. This is because the etching rate difference between the Ti-X alloy film and the pure Cu film is small. In the case of a Ti—O alloy film, a good etching shape was obtained by containing a predetermined amount of oxygen.

  For reference, the No. of Table 1 used in the experiment in FIG. 1 (pure Ti film / pure Cu film) and No. 1 of Table 1 used in the experiment in FIG. The result of the step length of 11-6 (Ti-30 atomic% Al film / pure Cu film) is shown. No. 11-6 is No. Compared to 1, the step length by etching was reduced, and it was found that a good etching shape was obtained.

  Furthermore, when it was investigated whether or not a good taper shape was obtained for each test piece during wiring processing by wet etching, the wiring films in which the Ti-X alloy film of the present invention and a pure Cu film were laminated were all good. It was found that a taper shape was obtained and the wet etching processability was excellent.

  For reference, FIG. 3A shows an etching rate when the etching solution A is used in the above experiment, and FIG. 3B shows an etching rate when the etching solution B is used. 3A and 3B, the case of using the Ti-X alloy film of the present invention (in the figure, compared to the case of using a pure Ti film in the first layer (O in the figure)). ●) had an excellent etching rate. On the other hand, it was found that the etching rate was worse than that of pure Ti when alloying elements other than the X group element of the present invention were used (■ in the figure).

  In the above embodiment, pure Cu is used for the second layer. However, it is assumed that the same result can be obtained when a Cu alloy containing elements such as Ni, Mn, and Zn is used. In addition, it has been confirmed by experiments that the same experimental results as described above are obtained when a Ti alloy film containing solute oxygen (Ti—O alloy film, Ti—X—O alloy film) is used.

Example 2
(Measurement of etching rate)
Ti-X alloy films (film thickness 300 nm) of various alloy elements shown in Tables 1 and 2 on a glass substrate (Corning Eagle XG, thickness = 0.7 mm, φ4 inch) by DC magnetron sputtering. Was formed into a single-layer sample. The sputtering ring conditions for the Ti—X alloy film are the same as those for the Ti—X alloy film described in Example 1 above. For comparison, a pure Ti film sample was prepared in the same manner.

  The etching rate of each produced sample was measured and evaluated. Specifically, after immersing each sample in each etching solution (Table 1 shows the case of the etching solution A and Table 2 shows the case of the etching solution B) (the temperatures of the etching solutions are both room temperature), the stylus The amount of film reduction of the sample was measured with a mold level meter (α-step manufactured by KLA-TENCOR). The etching rate (etching amount per unit time) was calculated from the film decrease amount and the slope of the etching time. With respect to a pure Ti film (each sample No. 1), a film obtained with an etching rate of 1.10 times or more was judged as ◯ (excellent wet etching property), and a film with less than 1.10 times was evaluated as x. Judged.

  The results are shown in Tables 1 and 2. In each table, the ratio of each sample to the etching rate of the pure Ti film (Ti alloy film / pure Ti film) is also shown. The larger this ratio, the smaller the difference from the Cu-based film, and the better the wet etching property.

From Tables 1 and 2, it can be considered as follows.
In the example using the Ti—X alloy film and the Ti—O alloy film described in Tables 1 and 2 containing a predetermined amount of the X group element defined in the present invention, than the pure Ti film (each table No. 1). The etching rate was excellent. Therefore, it was found that if the Ti-based alloy film of the present invention is used, wet etching processability is improved when a fluoride-containing etching solution is used.

  In the above, a Cu-based film is not laminated, but it has been confirmed by experiments that the ratio of the etching rate to the Cu-based film is also good.

Claims (6)

A wiring film for a display device or a touch panel sensor,
As an alloy component, an X group element (X is at least one selected from the group consisting of rare earth elements, Ge, Si, Sn, Hf, Zr, Mg, Ca, Sr, Al, Zn, Mn, Co, Fe, and Ni) Element) is contained in an amount of 3 to 50 atomic% and / or oxygen is contained in an amount of 0.2 to 3.0 mass%, and a Ti alloy layer made of the remaining Ti and inevitable impurities and a layer made of pure Cu or Cu alloy are included. A wiring film having a laminated structure of two or more layers.   The wiring film according to claim 1, wherein the Ti alloy layer is formed on an upper part and / or a lower part of the layer made of pure Cu or Cu alloy.   The wiring film according to claim 1, wherein the Ti alloy layer has a thickness of 10 to 100 nm.   The display apparatus provided with the wiring and / or electrode which were formed with the film | membrane for wiring in any one of Claims 1-3.   The touch panel sensor provided with the wiring and / or electrode which were formed with the film | membrane for wiring in any one of Claims 1-3.   It is a sputtering target used for formation of Ti alloy layer of Claim 1 or 2, Comprising: The said X group element is 3-50 atomic%, and / or oxygen is 0.2-3.0 mass%, and remainder Ti And a Ti alloy sputtering target, which is an inevitable impurity.