JP2009088049A - Liquid crystal display device - Google Patents

Abstract

【Task】
Provided is a liquid crystal image display device having excellent adhesion to a base, preventing copper and silicon from diffusing and having a low resistance copper wiring.
[Solution]
Using a copper-metal alloy target in which a metal having a negative free energy of formation of nitride is added on a substrate on which amorphous silicon or the like is formed, the main component is copper containing a metal element and nitrogen in a nitrogen + argon atmosphere. An alloy layer is formed. Next, an alloy film mainly containing copper containing a metal element having a diffusion barrier by forming an alloy film of copper and metal only with argon, and mainly containing copper containing a metal element and nitrogen. A laminated wiring with the alloy film is formed.
[Selection] Figure 1

Description

  The present invention relates to an active matrix liquid crystal display device driven by a thin film transistor and a manufacturing method thereof.

  The market for thin film transistor-driven liquid crystal display devices (TFT-LCDs) is expanding as an image display device that can be thin, lightweight, and high-definition. In recent years, with the increase in screen size, high definition, and high-speed driving of TFT-LCD, the resistance of wiring materials has been reduced.

  As the resistance decreases, the wiring material changes from chromium or molybdenum to aluminum, and a molybdenum / aluminum / molybdenum laminated structure using molybdenum or a molybdenum alloy for the cap layer or barrier layer is now the mainstream. However, the resistivity of pure aluminum has a lower limit of about 3 μΩcm.

  An example of a material having a lower resistance than aluminum is copper. However, there are some problems when copper is used as the wiring. First, the adhesiveness to the base is weak, and secondly, copper and silicon are likely to diffuse each other, and the wiring resistivity rises and the TFT characteristics deteriorate. In order to solve these problems, a structure in which a barrier layer is disposed between a copper wiring and a substrate or an interlayer insulating film and a manufacturing method thereof have been proposed.

  In Patent Document 1, at least one first metal selected from the group consisting of silver, gold, copper, aluminum, and platinum, and titanium, zirconium, hafnium, tantalum, niobium, silicon, boron, lanthanum, neodymium, samarium, and europium. , Gadolinium, dysprosium, yttrium, ytterbium, cerium, magnesium, thorium, and chromium, and simultaneously forming a first metal, and forming the second metal mainly composed of the first metal A wiring structure is shown in which a conductive layer made of a material containing the conductive layer is formed and the surface of the conductive layer is covered with an oxide layer made of a material mainly composed of the second metal.

  In Patent Document 2, in a semiconductor device, a refractory metal tantalum, tungsten, titanium, molybdenum, niobium, or a mixture thereof is used to form a crystalline nitrogen-containing metal film as an upper layer and an amorphous metal nitride film as a lower layer. A structure and a manufacturing method for forming a barrier film having a laminated structure and forming copper for a main wiring are shown.

JP-A-10-153788 Japanese Patent Laid-Open No. 2001-7204

  In Patent Document 1, an oxide layer mainly composed of a second metal is formed on the surface of a conductive layer mainly composed of a first metal and composed of a material containing a second metal by heat treatment in an oxygen atmosphere. However, it is considered that the oxygen atom of the oxide generated at the interface between the substrate and the conductive layer composed mainly of the first metal and containing the second metal is derived from the oxygen of the substrate which is an oxide. .

  Therefore, an oxide layer is not generated at the interface with silicon that is not an oxide. That is, since there is no barrier property on silicon, the TFT characteristics deteriorate due to diffusion of copper into silicon, and the resistivity decreases due to diffusion of silicon into copper. In addition, the adhesion between silicon and the conductive layer is weak and easy to peel off.

  Patent Document 2 is disadvantageous in terms of productivity because two types of raw material targets are required for the copper wiring and the diffusion barrier.

  Accordingly, an object of the present invention is to provide a liquid crystal display capable of preventing diffusion of copper into silicon and preventing diffusion of silicon into copper, providing a low resistance copper wiring excellent in adhesion to silicon, and improving productivity. Is to provide a device.

  In order to solve the above problems, the present invention provides a liquid crystal layer sandwiched between a pair of substrates, a plurality of scanning signal lines formed on one of the pair of substrates, and a plurality of scanning signal lines in a matrix. A plurality of video signal lines that intersect, a thin film transistor formed in the vicinity of the intersection of the scanning signal line and the video signal line, and a pixel electrode connected to the thin film transistor, and a source electrode, a drain electrode, and a video signal line of the thin film transistor Has a first alloy layer formed on the substrate and a second alloy layer formed on the first alloy layer, the first alloy layer comprising at least one metal element excluding copper and nitrogen. And the second alloy layer is an alloy film mainly containing copper containing an additive metal element common to the metal element of the first alloy layer. .

  It is possible to provide a liquid crystal display device capable of preventing diffusion of copper into silicon and silicon from diffusion, providing a low resistance copper wiring excellent in adhesion to silicon, and improving productivity.

  Embodiments of the present invention will be specifically described below in detail.

  As a form for carrying out the means for solving the above problems, the source electrode and the drain electrode, and the video signal line are composed of a laminated structure of a first alloy layer and a second alloy layer, and the first alloy layer is , An alloy film mainly containing copper containing at least one metal element excluding copper and nitrogen, and the second alloy layer contains a common additive metal element and the metal element of the first alloy layer. And it is the structure which is an alloy film which has as a main component copper which does not contain nitrogen more than unavoidable content.

  Specifically, as the metal element to be added, at least one element selected from aluminum, beryllium, chromium, gallium, hafnium, lithium, magnesium, manganese, niobium, titanium, vanadium, and zirconium is added. To do. In addition, among the metal elements, by adding at least one element selected from aluminum, titanium, and magnesium, the resistance of the alloy film containing copper as a main component can be further reduced.

  Furthermore, regarding the production of the target, it is desirable that it can be produced by a casting method in order to produce the target at a low cost.

  The addition amount of the metal element is preferably in the range of 0.1 to 2.0 atomic%. When the addition amount is more than 2.0 atomic%, the resistivity of the alloy film containing copper as a main component increases and it is difficult to reduce the resistance. On the other hand, when the content is less than 0.1 atomic%, the barrier performance is lowered, and silicon diffusion and copper diffusion occur, leading to an increase in resistivity and deterioration of TFT characteristics. In addition, sufficient adhesion to a substrate such as silicon cannot be obtained.

  Further, the alloy film containing copper as a main component and containing at least one metal element excluding copper and nitrogen is formed in the range of 1 nm to 50 nm. If the thickness is less than 1 nm, the adhesion and barrier properties are lowered, and it is difficult to prevent the peeling of wiring and the diffusion of silicon and copper. On the other hand, when the thickness is greater than 50 nm, the thickness of the main wiring portion of the laminated wiring is reduced, leading to higher resistance.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing an embodiment of an active matrix liquid crystal display device.

  A pair of substrates 1, 17, a liquid crystal layer sandwiched between the pair of substrates and having a liquid crystal 16, and a pair of polarizing plates 22 sandwiching the pair of substrates, between the one substrate 1 and the liquid crystal layer Scan signal line 2 as a gate electrode 2, gate insulating film 5, semiconductor layer 6, alloy film 12 containing copper containing metal element and nitrogen as a main component, alloy film 13 made of copper and metal, contact layer 7, drain A TFT formed by laminating an electrode 9 (video signal line) and a source electrode 10 is formed, and has a common signal line 3 and a common electrode 4, a protective insulating film 11 thereon, and a pixel thereon. An electrode 15 and an alignment film 18 are formed.

  Further, on the other substrate 17 side, a black matrix 19 is formed in a portion corresponding to the TFT, and a color filter 20 is formed in the display area. A planarizing film 21, on the black matrix 19 and the color filter 20, In this structure, the alignment film 18 is formed.

  A method for manufacturing the active matrix substrate (substrate 1 on which the TFT is formed) of the liquid crystal display device shown in FIG. 1 will be described with reference to FIGS. 2A to 6B, (a) shows a thin film transistor portion, and (b) shows a process flow. 2 to 6 are divided according to each photolithography process, and each figure shows a stage where the processing of the thin film after photolithography is completed and the photoresist is removed. In this description, photolithography means a series of steps of resist pattern formation from application of a photoresist to selective exposure using a mask and development thereof, and repeated description is avoided. The following explanation is based on the divided steps.

  FIG. 2 shows the first photolithography process. First, a transparent conductive film made of indium tin oxide is formed on a substrate 1 made of alkali-free glass by sputtering. Here, the transparent conductive film may be indium zinc oxide, indium tin zinc oxide, zinc aluminum oxide, or zinc gallium oxide. The film thickness is about 10 nm to 150 nm, and about 50 nm is preferable. Subsequently, the metal of the scanning signal line 2 is formed by sputtering. The film thickness was 400 nm. Next, a resist pattern is formed by photolithography using a half exposure mask. Here, a thick resist is formed on the portion where the scanning signal line 2 and the common signal line 3 are formed without exposure, and a thin resist is formed on the portion where the transparent common electrode 4 is formed as half exposure. After photolithography, the metal is etched, and then the transparent conductive film is etched. Here, the resist in the half exposure portion is removed by ashing. Through the above steps, the scanning signal line 2 (including the gate electrode and the scanning signal line terminal), the common signal line 3 (including the common signal line terminal), and the transparent common electrode 4 are formed.

  FIG. 3 shows a second photolithography process. First, a gate insulating film 5 made of silicon nitride, a semiconductor layer 6 made of amorphous silicon, and a contact layer 7 made of n + type amorphous silicon are successively formed by plasma chemical vapor deposition. After photolithography using a binary exposure mask, when the contact layer 7 and the semiconductor layer 6 are selectively etched and the resist is removed, a so-called island pattern is formed.

  FIG. 4 shows a third photolithography process. First, using a copper alloy target containing magnesium as an additive element, an alloy film containing copper as a main component and containing the metal element (magnesium) and nitrogen of the first alloy layer is formed by sputtering. The atmosphere during film formation is a mixed gas of nitrogen gas and argon gas, and the concentration of nitrogen gas in the mixed gas is 3.6%. Next, an alloy film containing copper as a main component and containing the metal element (magnesium) of the second alloy layer is continuously formed on the target. The film forming atmosphere at this time is argon gas. However, the second alloy layer may contain a smaller amount of nitrogen than the amount contained in the first alloy layer. In the formation of the first alloy layer, a mixed gas of rare gas and nitrogen gas is used as the sputtering gas, and in the formation of the second alloy layer, only the rare gas is used as the sputtering gas. Since the first alloy layer to the second alloy layer are continuously formed, even if the nitrogen gas is turned off after the formation of the first alloy layer, the nitrogen gas remains when the second synthetic layer is formed. This is because there is a possibility of being taken into the second layer.

  In addition to magnesium, the metal element added to the copper alloy is a metal element with negative free energy of formation of nitride (aluminum, beryllium, chromium, gallium, hafnium, lithium, manganese, niobium, titanium, vanadium, zirconium) You can choose from. After photolithography using a binary exposure mask, the laminated film of the alloy film containing copper containing magnesium and nitrogen as the main component and the alloy film containing copper containing magnesium as the main component is removed by etching, followed by n + type When the amorphous silicon layer is removed by etching and the resist is peeled off, the drain electrode 9 (including the video signal line and the video signal line terminal) and the source electrode 10 are formed. As described above, the source electrode 10, the drain electrode 9, and the video signal line are formed by laminating the first alloy layer and the second alloy layer in this order from the substrate 1 side. By adopting a structure, a liquid crystal display device capable of preventing diffusion of copper into silicon and silicon from diffusion, providing low resistance copper wiring excellent in adhesion to silicon, and improving productivity. Can be provided.

  Next, FIG. 5 shows a fourth photolithography process. First, the protective insulating film 11 made of silicon nitride is formed by plasma chemical vapor deposition. After photolithography using a binary exposure mask, a through hole 14 is opened in the protective insulating film 11 on the source electrode 10 and on the video signal terminal (not shown), and at the same time, protective insulation on the scanning signal line terminal (not shown). Through holes 14 are opened in the film 11 and the gate insulating film 5, and the resist is peeled off.

  FIG. 6 shows a fifth photolithography process. A transparent conductive film made of indium tin oxide is formed by sputtering. First, after photolithography using a binary exposure mask, the pattern of the pixel electrode 15, the scanning signal line terminal (not shown), the common signal line terminal (not shown) and the video signal line terminal (not shown) is etched. Strip the resist. The active matrix substrate of the liquid crystal display device is completed through the above steps.

(Embodiment 2)
Next, FIG. 11 is another cross-sectional view of an active matrix substrate in an active matrix liquid crystal display device (similar to Embodiment Mode 1).

  1 differs from the active matrix substrate of FIG. 1 in that, in FIG. 11, a semiconductor film 6 is formed on a gate insulating film 5 and laminated thereon to form a contact layer 7, copper containing a metal element and nitrogen. That is, the alloy film 12, the copper / metal alloy film 13, the source electrode 10, and the drain electrode 9 are formed. Further, the metal oxide layer 8 is formed. Others are the same as in FIG.

  A method for manufacturing the active matrix substrate shown in FIG. 11 will be described with reference to FIGS. In the manufacturing method of the active matrix substrate of the first embodiment, five times of photolithography are used, but in this embodiment, the four times of photolithography of FIGS. 7, 8, 10, and 11 are used. FIG. 9 shows a step of replacing the step of FIG. As in the first embodiment, in each of FIGS. 7 to 11, (a) shows a thin film transistor portion and (b) shows a process flow. The following explanation is based on the divided steps.

  FIG. 7 shows the first photolithography process. First, a transparent conductive film made of indium tin oxide is formed on a substrate 1 made of alkali-free glass by sputtering. Here, the transparent conductive film may be indium zinc oxide or indium tin zinc oxide. The film thickness is about 10 nm to 150 nm, and about 50 nm is preferable. Subsequently, an alloy film containing copper as a main component and containing a metal element (aluminum) is formed by sputtering. The film thickness is about 100 nm to 500 nm, and is 400 nm here. The metal element added to the copper alloy has an equilibrium oxygen pressure of oxidation reaction lower than the equilibrium oxygen pressure of indium oxidation reaction, and the diffusion coefficient of the metal element in copper is larger than the self-diffusion coefficient of copper. Moreover, the solid solubility limit in copper is larger than 0.1%. These elements can be selected from elements satisfying each of these elements or elements combined with all of them (in addition to aluminum, for example, beryllium, chromium, gallium, magnesium, manganese, titanium, vanadium, and zinc). Further, considering the source / drain wiring described later, it is desirable to select from among the above elements from aluminum, beryllium, chromium, gallium, magnesium, manganese, titanium, vanadium, and zinc. Furthermore, aluminum, magnesium, and titanium may be selected from the above elements in terms of resistivity.

  Moreover, the equilibrium oxygen pressure of the oxidation reaction of the metal element is lower than the equilibrium oxygen pressure of the oxidation reaction of silicon, and the diffusion coefficient of the metal element in copper is larger than the self-diffusion coefficient of copper.

The equilibrium oxygen pressure of the oxidation reaction is defined by the following formula _PO .

Here, ΔG _O is the free energy of formation of the oxide, n _O is the oxygen atom stoichiometric number of the oxide, R is the gas constant, and T is the temperature.

  Next, a resist pattern is formed by photolithography using a half exposure mask. Here, a thick resist is formed on the portions constituting the scanning signal line 2 and the common signal line 3 without exposure, and a thin resist is formed on the portion where the common (transparent) electrode 4 is formed as half exposure. After photolithography, an alloy film containing aluminum as a main component and containing aluminum is etched, and then the transparent conductive film is etched.

  Here, the resist in the half exposure portion is removed by ashing. After the ashing, the alloy film mainly composed of copper containing aluminum in the half-exposed portion is etched, and the resist is peeled off.

  Through the above steps, the scanning signal line 2 (including the gate electrode and the scanning signal line terminal), the common signal line 3 (including the common signal line terminal), and the common (transparent) electrode 4 are formed.

  FIG. 8 shows a second photolithography process. First, a gate insulating film 5 made of silicon nitride, a semiconductor layer 6 made of amorphous silicon, and a contact layer 7 made of n + type amorphous silicon are successively formed by plasma chemical vapor deposition.

  The film forming temperature is about 300 ° C., and at this time, a metal element (aluminum) is contained at the interface between the transparent conductive film formed in the first photolithography process and the alloy film mainly containing copper containing aluminum. A metal oxide layer 8 of a metal element added with an alloy film containing copper as a main component is formed. That is, the gate electrode and the scanning signal line of the thin film transistor include a transparent conductive film mainly composed of indium oxide, a metal oxide film formed on the transparent conductive film, and a copper formed on the metal oxide. And an alloy film containing as a main component. The added metal element of the alloy film, the added metal element of the metal oxide film, and the metal elements of the first alloy layer and the second alloy layer are common.

  Subsequently, an alloy film mainly composed of copper containing the metal element (aluminum) and nitrogen of the first alloy layer is formed by sputtering. The atmosphere during film formation is a mixed gas of nitrogen gas and argon gas, and the concentration of nitrogen gas in the mixed gas is 3.6%. Next, an alloy film mainly composed of copper containing the metal element (aluminum) of the second alloy layer is continuously formed. The film forming atmosphere at this time is argon gas.

  Next, a resist pattern is formed by photolithography using a half exposure mask. Here, the drain electrode 9 (including the video signal line and the video signal line terminal) and the source electrode 10 are not exposed to the resist, and the resist is formed thick, and the island pattern of the semiconductor layer 6 is formed. A thin resist is formed as half exposure. After photolithography, a laminated film of an alloy containing copper containing aluminum and nitrogen as a main component and an alloy containing copper containing aluminum as a main component is etched, and then an n + type amorphous silicon layer and an amorphous silicon layer are etched. Etch. Here, the resist in the half exposure portion is removed by ashing. After ashing, the channel of the thin film transistor is separated by etching the copper alloy laminated film and the n + type amorphous silicon layer in the half-exposed portion, and the resist is peeled off. Through the above steps, the drain electrode 9 (including the video signal line and the video signal line terminal), the source electrode 10, and the island pattern of the semiconductor layer 6 are formed.

  Note that the second photolithography process shown in FIG. 8 may be replaced with the process shown in FIG. In FIG. 9, first, a gate insulating film 5 made of silicon nitride, a semiconductor layer 6 made of amorphous silicon, and a contact layer 7 made of n + type amorphous silicon are successively formed by plasma chemical vapor deposition. The film forming temperature is about 300 ° C., and at this time, an additive element of the copper alloy is formed at the interface between the transparent conductive film formed in the first photolithography process and the alloy containing copper containing metal element (aluminum) as a main component. The metal oxide layer 8 is formed. Subsequently, an alloy film mainly containing copper containing the same metal element (aluminum) and nitrogen and an alloy film mainly containing copper containing aluminum are successively formed. The film forming atmosphere is the same as the process shown in FIG.

  Next, a resist pattern is formed by photolithography using a half exposure mask. Here, the resist pattern is formed in portions constituting the drain electrode 9 (including the video signal line and video signal line terminal) and the source electrode 10, and the resist is thickened without exposing the periphery of the channel of the thin film transistor. The resist is thinly formed on the other portions as half exposure. After the photolithography, the laminated film of the alloy film 12 containing copper containing metal element (aluminum) and nitrogen as the main component and the alloy film 13 containing copper containing metal element (aluminum) as the main ingredient is etched. Thus, the drain electrode 9 (including the video signal line and the video signal line terminal) and the source electrode 10 are formed, and the channel of the thin film transistor is separated by etching the n + type amorphous silicon layer. Here, the resist in the half exposure portion is removed by ashing (the resist removal process in the half exposure portion can be omitted), the remaining resist is reflowed, and the channel portion of the thin film transistor is filled with the resist. Subsequently, the island pattern of the semiconductor layer 6 is formed by etching the amorphous silicon layer.

  FIG. 10 shows a third photolithography process. First, the protective insulating film 11 made of silicon nitride is formed by plasma chemical vapor deposition. The film forming temperature is about 230 ° C. After photolithography using a binary exposure mask, a through hole 14 is opened in the protective insulating film 11 on the source electrode 10 and on the video signal line terminal (not shown), and at the same time protection on the scanning signal line terminal (not shown). A through hole 14 is opened in the insulating film 11 and the gate insulating film 5, and the resist is peeled off.

  FIG. 11 shows a fourth photolithography process. A transparent conductive film made of indium tin oxide is formed by sputtering. First, after photolithography using a binary exposure mask, the pattern of the pixel electrode 15, the scanning signal line terminal (not shown), the common signal line terminal (not shown), and the video signal line terminal (not shown) is etched. Then, the resist is peeled off. The active matrix substrate of the liquid crystal display device is completed through the above steps.

  According to the above embodiment, a gate electrode, a scanning signal line, a source, a drain electrode, and a video signal line can be manufactured using one target by selecting a metal element added to copper.

(Embodiment 3)
FIG. 12 shows a cross-sectional configuration diagram of the sample used in this example.

  A silicon nitride 35 (350 nm), amorphous silicon 36 (150 nm), and n + -type amorphous silicon 37 (20 nm) are deposited in this order on the alkali-free glass substrate 1 to produce a base substrate.

  Next, an alloy film 38 mainly composed of copper containing a metal element (magnesium) and nitrogen is formed by sputtering using a copper-1 atomic% magnesium alloy target. The film thickness was 20 nm. The film formation conditions at this time are, for example, film formation pressure: 2.5 mTorr, film formation gas: nitrogen gas (purity 99.999%) + argon gas (purity 99.999%), nitrogen concentration in the mixed gas: 3. 6%, DC power: 0.25 kW.

  Next, using the same target, the deposition atmosphere is made of argon gas alone, and copper containing metal and metal element (magnesium) is formed on alloy film 38 containing copper as a main component and containing metal element (magnesium) and nitrogen. An alloy film 33 having a main component of 300 nm is continuously formed. The film forming conditions at this time are, for example, film forming pressure: 1.4 mTorr, atmosphere: argon gas (purity 99.999%), DC power: 0.5 kW.

  The laminated film was subjected to vacuum heat treatment at 250 ° C., and the diffusion state of copper and silicon was measured by composition analysis in the film thickness direction. For comparison, an alloy film 33 mainly composed of copper containing a metal element (magnesium) was formed on a base substrate, and the same heat treatment and composition analysis were performed. FIG. 13 shows the analysis result of Comparative Example 1. In the comparative example, since there is no alloy film 38 mainly composed of copper containing a metal element (magnesium) and nitrogen, copper diffuses into the base substrate and silicon diffuses into the copper. On the other hand, FIG. 14 shows the analysis result of the present invention. By disposing the alloy film 38 mainly composed of copper containing a metal element (magnesium) and nitrogen, diffusion of copper to the base substrate is suppressed. Therefore, the alloy film 38 mainly composed of copper containing the metal element (magnesium) and nitrogen according to the present invention sufficiently satisfies the function as a diffusion barrier.

  The adhesion of the sample after film formation was evaluated. The evaluation method is a crosscut test. FIG. 15 shows the measurement results. A sample without the alloy film 38 containing magnesium and nitrogen containing copper as a main component had poor adhesion to the base and was peeled entirely. On the other hand, the sample in which the alloy film 38 mainly composed of copper containing magnesium and nitrogen is formed is not peeled off from the base substrate, and sufficient adhesion can be obtained.

  Also, copper and magnesium alloy targets having different amounts of magnesium added were prepared, and alloy films 38 mainly composed of copper containing metal elements (magnesium) and nitrogen having different amounts of magnesium added were formed. Next, an alloy film mainly containing copper containing the metal element (magnesium) was continuously formed on the alloy film 38 containing copper containing the metal element (magnesium) and nitrogen as a main component, thereby preparing a sample. . FIG. 16 shows the resistivity measurement results. The resistivity increases when the amount of magnesium added is greater than 2 atomic%. Therefore, the addition amount is optimally 2 atomic% or less.

  In this example, magnesium was described as the metal element, but the same characteristics as described above are obtained even when aluminum, beryllium, chromium, gallium, hafnium, lithium, manganese, niobium, titanium, vanadium, or zirconium is used. .

(Embodiment 4)
An alloy film mainly composed of copper containing a metal element (aluminum) having different film thickness and nitrogen on a base substrate produced in the same manner as in Example 3 using a copper-0.5 atomic% aluminum target. 38 was formed by sputtering. The film formation conditions at this time are, for example, film formation pressure: 2.5 mTorr, film formation gas: nitrogen gas (purity 99.999%) + argon gas (purity 99.999%), nitrogen concentration in the mixed gas: 3. 6%, DC power: 0.25 kW. By changing the film formation time, an alloy film 38 mainly composed of copper containing metal elements (aluminum) and nitrogen having different film thicknesses was produced.

  Next, an alloy film mainly composed of copper containing a metal element (aluminum) is continuously formed at 270 nm on the alloy film 38 mainly composed of copper containing aluminum and nitrogen with only argon gas. Filmed. The obtained sample was subjected to a vacuum heat treatment, and the barrier properties of an alloy film mainly composed of copper containing aluminum and nitrogen were evaluated. It has been clarified that an alloy film containing copper and aluminum containing aluminum and nitrogen as a main component has a barrier performance with a film thickness of 1 nm or more. However, when the film thickness of the diffusion barrier is increased, the time required for film formation becomes longer, which may lead to a decrease in productivity. Therefore, in the present invention, if the film thickness is 1 nm to 50 nm, the effect as a diffusion barrier can be sufficiently obtained.

It is sectional drawing which shows one Embodiment of the liquid crystal display device based on this invention. It is a figure which shows 1 process of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the other manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the other manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the other manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the other manufacturing method of the active matrix substrate of this invention. It is a figure which shows 1 process of the other manufacturing method of the active matrix substrate of this invention. It is a figure which shows one cross section of the sample of the active matrix substrate of this invention. It is a figure which shows the barrier characteristic of a comparative example. It is a figure which shows the barrier characteristic of this invention. It is a figure which shows the adhesive test result of this invention. It is a figure which shows the relationship between Mg addition amount and resistivity of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Scan signal line 3 Common signal line 4 Common electrode 5 Gate insulating film 6 Semiconductor layer 7 Contact layer 8 Metal oxide layer 9 Drain electrode (video signal line)
DESCRIPTION OF SYMBOLS 10 Source electrode 11 Protective insulating film 12 Alloy film 13 mainly composed of copper containing metal element and nitrogen 13 Alloy film 14 made of copper and metal element Through hole 15 Pixel electrode 16 Liquid crystal 17 Glass substrate 18 for color filter Black matrix 20 Color filter 21 Flattening film 22 Polarizing plate

Claims (14)

A pair of substrates; a liquid crystal layer sandwiched between the pair of substrates; a plurality of scanning signal lines formed on one of the pair of substrates; and a plurality of scanning signal lines intersecting the plurality of scanning signal lines in a matrix. A video signal line, a thin film transistor formed near an intersection of the scanning signal line and the video signal line, and a pixel electrode connected to the thin film transistor,
The source electrode and drain electrode of the thin film transistor and the video signal line have a first alloy layer formed on the substrate and a second alloy layer formed on the first alloy layer,
The first alloy layer is an alloy film mainly composed of copper containing at least one metal element excluding copper and nitrogen.
The liquid crystal display device, wherein the second alloy layer is an alloy film mainly composed of copper containing an additive metal element common to the metal element of the first alloy layer. The liquid crystal display device according to claim 1.
A liquid crystal display device in which a free energy of formation of the nitride of the metal element contained in the first alloy layer is negative. The liquid crystal display device according to claim 1.
The liquid crystal display device in which the second alloy layer contains a smaller amount of nitrogen than the amount contained in the first alloy layer. The liquid crystal display device according to claim 2.
The metal element contained in the first alloy layer and the second alloy layer is at least one selected from aluminum, beryllium, chromium, gallium, hafnium, lithium, magnesium, manganese, niobium, titanium, vanadium, and zirconium. This is the liquid crystal display device. The liquid crystal display device according to claim 4.
The liquid crystal display device, wherein the metal element contained in the first alloy layer and the second alloy layer is at least one selected from aluminum, titanium, and magnesium. The liquid crystal display device according to claim 4.
The liquid crystal display device, wherein a content of the metal element contained in the first alloy layer and the second alloy layer is in a range of 0.1 atomic% to 2.0 atomic%. The liquid crystal display device according to claim 4.
The liquid crystal display device wherein the thickness of the first alloy layer is in the range of 1 nm to 50 nm. The liquid crystal display device according to claim 1.
The gate electrode and the scanning signal line of the thin film transistor include a transparent conductive film mainly composed of indium oxide, a metal oxide film formed on the transparent conductive film, and a copper formed on the metal oxide. And an alloy film mainly composed of
The liquid crystal display device in which the additive metal element of the alloy film, the additive metal element of the metal oxide film, and the metal element of the first alloy layer and the second alloy layer are common. The liquid crystal display device according to claim 8.
The equilibrium oxygen pressure of the oxidation reaction of the metal element is lower than the equilibrium oxygen pressure of the indium oxidation reaction, and the diffusion coefficient of the metal element in copper is larger than the self-diffusion coefficient of copper. The liquid crystal display device according to claim 9.
The liquid crystal display device in which the metal element is added with at least one element selected from aluminum, beryllium, chromium, gallium, magnesium, manganese, titanium, vanadium, and zinc. The liquid crystal display device according to claim 1.
The gate electrode of the thin film transistor and the scanning signal line have a metal oxide film and an alloy film mainly composed of copper formed on the metal oxide film,
The liquid crystal display device in which the additive metal element of the alloy film, the metal element of the metal oxide, and the metal element of the first alloy layer and the second alloy layer are common. The liquid crystal display device according to claim 11.
The equilibrium oxygen pressure of the oxidation reaction of the metal element is lower than the equilibrium oxygen pressure of the oxidation reaction of silicon, and the diffusion coefficient of the metal element in copper is larger than the self diffusion coefficient of copper. The liquid crystal display device according to claim 12.
The liquid crystal display device to which at least one of the metal elements is added among aluminum, beryllium, magnesium, and titanium. The liquid crystal display device according to claim 1.
The step of forming the first alloy layer and the second alloy layer constituting the source and drain electrodes of the thin film transistor and the video signal line is performed by using the same sputtering target in the first alloy layer and the second alloy layer. As a raw material, the sputtering target is an alloy mainly composed of copper containing an additive metal element common to the second alloy layer and the first alloy layer, and in the step of forming the first alloy layer, a rare gas and nitrogen are used. A method for manufacturing a liquid crystal display device, wherein a mixed gas with a gas is used as a sputtering gas, and a rare gas is used as a sputtering gas in the step of forming the second alloy layer.

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